Wikipedia:Reference desk archive/Science/November 2005

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[edit] November 1

[edit] sea water what is the boiling point?

I once did the calculation for water with salt added to find out if that would make potatoes cook faster, and the result was something barely over 100 C (just a tenth of a degree or something). I assume sea water won't be much different, so my guess is something like 100.1 C.

It depends how much salt you add. Sea water is generally about 3.5% salt by weight (35 grams per kilogram), and this page shows how to calculate the change in boiling point: add 0.5ºC for every 29.2 grams of salt per kilogram of water. So 35 grams (3.5% of one kilogram) of salt per kilogram of water would add about 0.6ºC to the boiling point. In other words, the boiling point of seawater is about 100.6ºC.
Note: it probably would have been quicker to find the page yourself, but interesting question, nonetheless. --jonon 06:38, 5 November 2005 (UTC)

[edit] what colour is water

pink I've had many a debate about this and have read different explainations. So i thought I'd see what you guys thought. What colour is water ??? The dictionary describes it as a colourless, odourless liquid. if this is true why are oceans green and blue. This has been explained away by saying that blue oceans typically contain zooplankton and green oceans contain more degrees of photoplankton. -- freddy

I agree. Pure water is colorless. The blue color in lake water and blue-green color in seawater are due to impurities. StuRat 00:25, 1 November 2005 (UTC)
  • Pure water is slightly blue, because there's an (weak) overtone of the O-H stretch absorption resonance in the red. (Pure heavy water - deuterium oxide - is colourless because the O-D stretch is at a longer wavelength). Scattering almost certainly plays a part, too. But these are very weak effects and most of the colour in the oceans is due to sealife. --Bob Mellish 00:33, 1 November 2005 (UTC)
    Indeed so. For more details, see [1]. —Ilmari Karonen (talk) 00:45, 1 November 2005 (UTC)
    Also, note that much of the blue color seen on the surface of the sea is simply reflected from the sky (which is blue due to scattering). On an overcast day, the sea generally looks rather gray too. —Ilmari Karonen (talk) 00:50, 1 November 2005 (UTC)
I'm glad somebody mentioned the sky. One might say air is clear, but with enough of it, and at a distance, it is clearly blue. I'm speaking of the air we breath ofcourse, and the blue sky we see as a result of it. The same analogy can be used to deduce the color of water. A handful of water may appear to be clear, but with enough of it, even free of any impurities, it may in fact take on a blue hue. I would have to agree with Bob Mellish. - Cobra Ky (talk, contribs) 03:21, 1 November 2005 (UTC)
Note that the sky isn't actually necessarily blue. See our article on Rayleigh scattering for an explanation of why the sky usually appears blue, but why thicker slabs of air (as seen at sunset, for example) can appear other colours. (See also green flash for a really neat atmospheric phenomenon.) Lastly, check out Mie theory for an examination of how suspended particulate matter (volcanic dust, industrial pollution) can also colour the sky. (Oops—I shouldn't forget diffuse sky radiation, too.) The apparent blue colour of the sky isn't due solely to intrinsic 'colour' of the air, but a combination of scattering effects, the nature of the source of illumination (the Sun), and the sensitivity of the photoreceptors in our eyes. TenOfAllTrades(talk) 03:51, 1 November 2005 (UTC)
This is a great question. If you assume the light source is our sun, the answer will depend on the depth or thickness of the water sample, and where you are viewing the water from. From above, the sea is the color of the sky. A spectrometer can measure the light frequencies absorbed by media, such as water. Let the spectrometer print out the graph, dependent on the thickness of the water sample. So 'colorless' is correct if the sample is thin enough. But for enough water, the light which passes through will appear slightly 'green-tinted'. And if you are at the bottom of the ocean, it's 'black'. Ancheta Wis 08:34, 9 November 2005 (UTC)

[edit] Wind Strength

What methods do meteorologists use to measure wind strength?

They use an anemometer? --cesarb 02:26, 1 November 2005 (UTC)
And here I thought that device was used to measure the number of sea anemones in an area. StuRat 02:36, 1 November 2005 (UTC)
An anemometer measures wind speed, so a wind's strength is just its peak gust speed.--Commander Keane 05:43, 1 November 2005 (UTC)

[edit] Flash Drive

Would i be able to download a DVD players and save it to a Flash drive and then save it to another computer?

You certainly can, there are many legally availbale DVD players online, a bunch of them a listed here. Download the installation file and copy it to which ever computer you wish to install it on. Akamad 02:25, 1 November 2005 (UTC)

[edit] Runge-Kutta Method

I understand how to use Runge-Kutta methods to solve a first order differential equation, but I'm not sure how to adapt it to a second order equation like the harmonic oscillator. I'd assume you'd break the second order equation into two first order equations, (and I have solved this problem using Euler's method) but I don't know how to adapt the more accurate RK procedure to two coupled equations.

Anyone know of any good references either in print or online to help me learn it? Thanks. Vonspringer 04:08, 1 November 2005 (UTC)

I know I was supposed to learn this last semester, but I'd have to go grab my textbook to give you the details. I believe if you're only interested in a numerical (as opposed to analytic) solution, the trick is to turn the second-order equation into a system of first-order equations. So if you have y''=2*y, you can turn this into the system {u=y'; u'=2*y}. Does that make sense? I'll try to remember to bring Heath's text in tomorrow. —HorsePunchKid→龜 07:44, 1 November 2005 (UTC)

[edit] "Local Mode" showing on my Nokia phone

Hi,

I have a cheap Nokia phone (don't know the model) which has suddenly frozen with the words "Local Mode" showing. It can't be turned on or off. Some internet searching shows that this is something to do with testing and/or transfering files, or something, but I can't find out how to unfreeze the phone. Any thoughts? Thanks!

If you're using a data cable (e.g. a USB cable that plugs into the phone), follow this advice: "In my experience for many 8310/6510's just disconecting and reconnecting the data cable is not always sufficient as the words "Local mode" remain displayed. If this is the case simply remove the USB power cable for a second and plug it back in." If you are not using a data cable, then I believe that the phone's flash has been corrupted, take it into any phone shop and they should be able to flash it for you. If you want to know the model of the phone, take out the battery, it'll be written on the white sticker underneath. Good luck! --08:29, 1 November 2005 (UTC)

[edit] RED HAT ENTERPRISE LINUX

WHAT IS RED HAT ENTERPRISE AND WHY IS IT AN OPTION

WHAT IS RED HAT ENTERPRISE LINUX?

Red Hat Linux is a particular distribution of the GNU/Linux operating system. It is a relatively popular choice for server administrators who want a cheap, unix-like operating system but who still want paid tech support as an option. —HorsePunchKid→龜 07:38, 1 November 2005 (UTC)

[edit] Planetary sling shot

Space craft that go beyond Mars are quite often accelerated using a sling shot effect, by passing close by some heavenly body. Of course they will get accelerated when they approach it, but after that they have to escape the gravitational pull to continue, which would annihilate the effect. So how does this work? I imagine it has something to do with either the change in direction or approaching the planet (or whatever) 'from behind' (relative to its motion), thus not using the gravitational pull but the speed of the planet. DirkvdM 10:47, 1 November 2005 (UTC)

amakuru mu kirundi

I've been to Burundi, but the only local language I made an attempt at was Kiswahili, so what does this mean? DirkvdM 09:10, 2 November 2005 (UTC)

There are three types of orbital motion, parabolic, (ballistic trajectory) elliptical, and hyperbolic. By approaching a planet in a hyberbolic orbit, we don't accelerate from the gravity of the planet, but we acquire the velocity or twice the velocity of the planet's motion. If the planet was stationary, all we would do is change direction. Since the planet is moving, we acquire the velocity of the planet while accelerating around it in the hyperbolic orbit. A good explanation is here. [2]Dominick (ŤαĿĶ) 12:48, 1 November 2005 (UTC)

The key is that the spacecraft steals some angular momentum from the planet. Since the planet is so much bigger than the spacecraft, the planet's speed changes negligibly, but the spacecraft gets a big boost. If the planet were stationary than the trick would only change the spacecraft's direction. — Laura Scudder | Talk 16:37, 1 November 2005 (UTC)

  • This requires a bit longer answer.

The trick to thinking of this situation easily is to use frames of reference. Imagine you are standing on a road, looking south, and a car comes toward you at a speed of 50 (mph or km/h, whatever units they use where you live). You throw a ball directly toward the front of the car, at a speed of 40, and step out of the way. They are closing at a relative speed of 90... that is, in the car's frame of reference, the ball is moving south at a speed of 90. We assume that the car and the ball are perfectly elastic bodies, that is, the ball does not waste energy in denting the car or anything like that. Then the ball will bounce back from the car at a speed of 90 in the opposite direction, north. But that's 90 relative to the car... so in your frame of reference it's now going at 140! Don't try this at home!

Now consider the same situation, only this time you turn away from the car and throw the ball north at a speed of 20 (before stepping aside), so that the car catches up with it. The car is moving north at 50, so in the car's frame of reference the ball is moving south at 30. Hitting the car, it bounces north at 30 in the car's frame of reference... which is 80 in yours. Same idea as the first experiment, although the speed change is less dramatic in this case.

In both cases, if you measure closely you will find that the car has slowed a little, as the ball stole some of its momentum. This shows up as a change in the speeds of the two frames of reference relative to each other. But for purposes of understanding the experiment, this can be pretty much ignored.

The car example is one-dimensional. For planets and spacecraft, you have to think in at least two dimensions. Here is how it looks in the planet's frame of reference: The spacecraft approaches from a distance and falls toward the planet on an off-center path. The planet's gravity causes it to follow a hyperbolic orbit. The symmetry of this shape means that the spacecraft departs at the same speed as it was approaching originally, but in a different direction. The effect is very much as if the spacecraft had simply bounced off the planet, even though it is being pulled by the planet's gravity, and not pushed by the (electromagnetic) forces involved in bouncing a ball.

Okay now, in your frame of reference, the planet is moving along its orbit. For simplicity, say it comes up almost directly behind she spacecraft, like the second car/ball example. Then in your frame of reference, the spacecraft may end up moving in very much the same direction as before, but considerably faster. The details of the before and after directions are actually more complicated and not the sort of thing you can do in your head; for one thing, it depends on how close the spacecraft comes to the planet. But this gives the general idea.

(Typically the planet and spacecraft will be moving in the same direction, like the second car example; this is because the Earth's own orbit, which is also in the same direction, determines which orbits can be reached at reasonable cost.)

You asked if it is "not using the gravitational pull but the speed of the planet". You should now see that it is using the gravitational pull in order to use the speed of the planet. It has stolen a tiny bit of momentum from the planet (and, in the same interaction, some of its angular momentum as well).

--Anonymous, 00:17 UTC, November 2, 2005

So, if I get it right, what it comes down to is that the spacecraft steals some of the momentum of the planet (which, for all practical purposes has an infintitely larger mass). Dominick's link was quite helpful (if a bit too mathematical - I prefer understanding things on a more 'philosophical' level). Thanks. DirkvdM 09:10, 2 November 2005 (UTC)
We have a gravitational slingshot article. --Heron 21:22, 6 November 2005 (UTC)

[edit] Psychoactive Drugs

I was wondering if any societies, past or present take psychoactive drugs to control any unwanted behaviors?--207.119.216.109

Societies don't take drugs. People do. If you are asking if there are any societies in which individuals are encouraged to take psychoactive drugs to control unwanted behavior, the answer is of course: ours. Nearly all psychoactive drugs except antidpressants are prescribed for unwanted behavior. alteripse 16:00, 1 November 2005 (UTC)

Ritalin is a good example. I suspect you meant to ask about psychoactive drugs which are illegal in the West, such as cocaine. Is that correct ? StuRat 16:50, 1 November 2005 (UTC)
Of course there is also a third category, non-prescribed (ie recreational) drugs that are legal in the West today, but those are pretty much a rarity, alcohol, nicotine and cafeine being exceptions. In modern pressure cooker society laziness is rather unwanted behaviour and cafeine helps remedy that. DirkvdM 09:18, 2 November 2005 (UTC)
Ritalin is the best example of a drug imposed on children through society. These days, many American children are expected to be protiges and big-time pros at skills through the guidance of their parents. This stress and immediate stress on schoolchildren has manifested itself in a new industry in the United States--the Leap ahead movement involving Leapfrog, tutors, college coaches, the Kaplan/Princeton Review courses, and an enormous amount of marketing to college-savvy parents who want their children to all grow up as great experts and masters of the world. Ritilin is pressured on many children who do not have ADD because school administrators--especially those in small schools--pressure parents to advance their children with psychoactive drugs. The millions of American schoolchildren wouldn't be on ritalin if American society didn't place such immediate demands on children to behave in the rigid institutionalized school system. If you are interested in fictional dystopias with drug use, the Giver and Brave New World were excellent books describing what drug-altered societies would look like.--Screwball23 talk 19:40, 2 November 2005 (UTC)
The people of Borneo used the plant life of their island to go into stupors etc. They also used plants as abortifacients. These behaviors were discouraged by the governments of Borneo in the 19th C. Reference: 1911 Encyclopedia Britannica. --Ancheta Wis 02:50, 10 November 2005 (UTC)

[edit] Chemistry

What happens when an alcohol burns? If the reaction is exothermic or endothermic or not.Please also explain the bond in the alcohol, how it is broken and how products are formed.

Dont forget combustion Theresa Knott (a tenth stroke) 23:40, 1 November 2005 (UTC)
Burning is the process of oxidation. Cars that compete in the Indianapolis 500 car race burn alcohol. More news at 11:00 Artoftransformation 13:16, 4 November 2005 (UTC)


Practically all combustion (burning) is an exothermic chemical reaction. The burning of practically all organic compounds, including alcohol, is overall a chemical chain reaction (not a nuclear chain reaction) which consists of a complex series of individual chemical reactions involving unstable pieces of molecules called free radicals as intermediate reactants and products. This detailed series of chemical "sub"-reactions making up an overall chemical reaction is called the overall reaction's mechanism. Combustion reaction mechanisms are usually very complicated and, depending on what is burned, are not always fully known. H Padleckas 19:44, 13 November 2005 (UTC)

[edit] Technical Terms

I have a BA in English. I work as a technical writer. I've been using your site as a tech. dictionary with a good deal of success! and appreciate all that you offer. But, today I came across the need to read a definition of:

Tab delimited Pipe delimited

and neither were located on your site. Can you recommend where else I can obtain a definition?

Who is your closest competition for offering explanation of technical issues/concepts/terms?

Thanks, Peggy McLean, VA

  • Both refer to file or data formats. "Tab delimited" means items are separated by tab characters (ASCII code 9). So the file might look like "10<tab>20<tab>5.5<tab>100" etc., to represent the numbers 10, 20, 5.5, 100 in that order. "Pipe delimited" means the same thing but separated with the pipe "|" character (ASCII code 124). So the same file would be "10|20|5.5|100". Tab delimited files are common for spreadsheets and the like. I don't know what type of program would use pipe delimited. --Bob Mellish 19:02, 1 November 2005 (UTC)
Pipe delimited text is common for many data formats (HL7 for one). It is simply a matter of choosing a character that will likely not be used in the data itself. The choice of commas and tabs always struck me as rather dumb since both are common in user-data. Kainaw 19:10, 1 November 2005 (UTC)
There is a Wikipedia article on this at Delimited. I will add redirects so that this can be found using the search terms you used. -- Canley 01:56, 2 November 2005 (UTC)

For technical terms try One Look. It searches a variety of dictionaries for you, including many technical dictionaries. ike9898 18:54, 4 November 2005 (UTC)

As a note, one of the "dictionaries" searched is our own Wikipedia. :) Superm401 | Talk 03:11, 6 November 2005 (UTC)

[edit] The Archives of the Internet

I would like to see the history of the internet. If I could see a group of websites and look at their archives, I could learn quite a few things of interest. I would like to see how certain websites changed, or how many ads there were on the most popular webpages back in the 80s and how campaign webpages change as an election progresses, and maybe even see dead websites, or ones that are not updated often. Is there a place where I can see the archives of the internet? I looked at archives.org and I was disappointed. I wasn't able to search very easily at that site. Are there any others? Where can I view these archived websites?--Screwball23 21:21, 1 November 2005 (UTC)

Why don't you log in as a user? This isn't a requirement but you seem to be expending some effort to appear logged in. --hydnjo talk 21:57, 1 November 2005 (UTC)
OK then. It seems that you are logged in and just not sig linked. Sorry, I was confused. --hydnjo talk 00:36, 2 November 2005 (UTC)
Archive.org isn't intended to show you "the internet of a certain date", but rather what a specific site looked like on a certain date. It is, however, the only major archive service I know of for the web - there are no single "archives of the internet", because the internet is not a centralised collection of information.
Note also that there were no webpages in the 80s; you could try reading the Usenet archives at groups.google.com, perhalps... Shimgray | talk | 22:10, 1 November 2005 (UTC)
  • You won't find any records of web sites from the 1980s anywhere; the Internet was around then, but the Web is only part of it, and wasn't started until 1990. See those two links and also History of the Internet. --Anonymous, 22:20 UTC, November 1, 2005
I always thought of the internet and computers in the late '80s. You're right. The World Wide Web wasn't in the '80s. That was interesting to know.--Screwball23 talk 03:18, 2 November 2005 (UTC)

[edit] The most popular websites now

What are the most popular websites people visit in the US? Is it much different across the world? What about the number of google searches people do everyday? Is there a list of the most popular google searches? How has that changed with time?--Screwball23 21:25, 1 November 2005 (UTC)

Why don't you log in as a user? This isn't a requirement but you seem to be expending some effort to appear logged in. --hydnjo talk 21:59, 1 November 2005 (UTC)
Actually, he was logged in. He just hasn't made his name clickable. --Pidgeot (t) (c) (e) 23:57, 1 November 2005 (UTC)
Ah, Ok thanks. --hydnjo talk 00:31, 2 November 2005 (UTC)

[edit] November 2

[edit] pharmacokinetics?

I am wondering what the impact of renal failure, genetics or ethnicity and hypoalbuminemia is on absorption, distribution, metabolism and excretion of drugs?--24.235.133.63 00:18, 2 November 2005 (UTC)

  1. Renal failure slows the excretion of those drugs that are eliminated from the body by urinary excretion rather than metabolism. It has less effect on absorption, distribution and metabolism (with certain exceptions for each category).
  2. Genetics accounts for small differences in rates of metabolism for many drugs, large differences for a few. Few genetic differences are of major clinical significance. Genetic differences of absorption, distribution, and excretion are less important, assuming major organ systems are properly working.
  3. Ethnicity is a subset of genetic differences. All items are as described above for genetics.
  4. Hypoalbuminemia affects those drugs that bind to albumin. It can accelerate metabolism, restrict apparent distribution volume, and accelerate renal excretion.

Now, don't you feel a little embarrassed queuing up with the seventh graders to have your homework done? I hope you aren't taking care of patients any time soon. alteripse 02:00, 2 November 2005 (UTC)

And on behalf of the world's *patients* I sincerely hope you (the anonymous med student, not Alteripse) aren't looking after us any time soon. Sheesh. Haven't you heard of the damn textbook? --Robert Merkel 02:56, 2 November 2005 (UTC)

[edit] solubility

how can differences in solubility be used to separate a mixture of solids?

how can differences in solubility be used to solve homework questions? --R.Koot 02:36, 2 November 2005 (UTC)
  • Try reading solubility and precipitation (chemistry). If you can get one substance to dissolve while the other one doesn't, you can filter off the nonsoluble substance and separate the mixture. - Mgm|(talk) 21:19, 2 November 2005 (UTC)
Various solvents or mixtures of solvents can be tried to dissolve one (or more) of the solids, but not dissolve the others. Alternatively or in combination, selective precipitation of some of the solids may be tried. After that filtration can be used to separate the solids from liquid. H Padleckas 20:14, 13 November 2005 (UTC)

[edit] Applying imaginary numbers type -- Mathematics

What occupations require the use of imaginary numbers referred to as "i" (i^0, i^1, i^2, i^3, etc)?

Electrical engineering do, to analyze circuits. They're also important in signal processing. There are other fields, probably, too. Dysprosia 02:48, 2 November 2005 (UTC)
Like math teaching? alteripse 03:08, 2 November 2005 (UTC)
Of course! But that's probably not what the question-asker had in mind, I think ;) Dysprosia 04:40, 2 November 2005 (UTC)
Researcher in physics, computer science (quaternions are of some use in computer graphics). --R.Koot 03:18, 2 November 2005 (UTC)
Quantum mechanics. Really, all of physics. eix is a convenient shorthand for sines and cosines if nothing else -- SCZenz 03:24, 2 November 2005 (UTC)
Economics! In fact, the famous Mandelbrot set was the result of Benoit Mandelbrot's studies into the fluctuations of the price of cotton over the centuries. --jpgordon∇∆∇∆ 03:31, 2 November 2005 (UTC)
Engineering, of course. Or really anything that applies analysis. — Sverdrup 23:36, 2 November 2005 (UTC)

[edit] Chemistry - PAN

A PAN is a polyatomic negative ion or a polyatomic nonmetal group. What does this mean (in English please)? Also, what are the 7 Home Base PANs?

Polyatomic negative ion, or a radical, is a molecule made of several atoms that does not have its electic charges balanced. An example is hydroxide (OH), with a charge of -1. The other ones, I'm not sure, I'm not a chemist). Titoxd(?!?) 03:27, 2 November 2005 (UTC)

I haven't heard that term before, but there are a number of polyatomic negative ions important in biology: PO4, SO4, HCO3, NO3. Here is a link that gives many more: [3] alteripse 04:15, 2 November 2005 (UTC)

I haven't heard the term either: PAN in chemistry usually refers to polyacrylonitrile. The above ions should be PO43-, SO42-, HCO3- and NO3-: many more examples can be found in Category:Anions. All the atoms in the above anions are nonmetals. Physchim62 (talk·RfA) 06:21, 2 November 2005 (UTC)

[edit] Parasite

What is the name of the parasite that turns ants into zombies thay get ate by rabbits that releases it's eggs in rabbit feces that snails eat that cough up a snot/parasite ball that is ate by an ant which is turned into a zombie that get ate by rabbits that....

The concept of this ant is an intellectual spore disseminated by the Museum of Jurassic Technology [4]. It gradually expands to take up more and more of your waking thoughts. At a certain point it will induce you to root around in the dirt until you unearth a computer cable, at which point you will clamp your jaws permanently around it with no desire to eat or drink ever again. As your desiccated body disintegrates the spores of the idea penetrate the cable and are disseminated to other unsuspecting victims. alteripse 10:32, 2 November 2005 (UTC)

  • I think Trematoda is what you are lookign for. 10:36, 2 November 2005 (UTC)

Could it be the Lancet Fluke dicrocoelium dendriticum [5] zombification of the ant? Dominick (ŤαĿĶ) 15:18, 2 November 2005 (UTC)

Looks like a near-perfect match to me. I suspect the resemblance between this story and the MJT version above is no coincidence. alteripse 16:03, 2 November 2005 (UTC)

[edit] Temperature variation of air.

Why is flowing air always cooler than static air? Is it an apparent phenomenon or is it due to the change in energy of the air molecules? --StratOnLSD 11:48, 2 November 2005 (UTC)

Moving air is capable of allowing for evaporation from the skin more easily than still air, thus cooling the skin. This is because of two reasons: firstly the air is continually replenished and replaced by drier air, and secondly moving air has lower pressure, thanks to Bernoulli's principle (See vapour pressure). -- Ec5618 12:01, 2 November 2005 (UTC)

Flowing air is cooler only to your skin, not to a thermometer. Flowing air removes the air you have warmed and replaces it with cooler air. It can also accelerate perspiration or moisture loss in some circumstances, which is also cooling. alteripse 11:58, 2 November 2005 (UTC)

An interesting note is that at high temperature and high humidity, wind (moving air) will actually feel warmer than still air. This is because as humidity rises, your body can no longer use evaporation as a means of cooling, and moving air then feels more like a heater than an air-conditioner. --Quasipalm 14:17, 2 November 2005 (UTC)
On hot days in Perth (eg above 40°C = 104°F), even though the humidity can be as low as 20%, the wind is hot on the skin. It's not to do with humidity in that case.--Commander Keane 06:16, 3 November 2005 (UTC)
The reason for which would be that this is air that is hotter than the body temperature. If the air stands still a layer of air is formed around the body that is closer to the body temperature. So when the air moves that layer is replaced with the hotter air. Conversely, if the temperature of the air is below body temperature that will help the body to release its heat, thus cooling it down. By the way, an airconditioner works by cooling the air down. A better comparison would be a fan, which also works by moving air past your body. DirkvdM 10:06, 3 November 2005 (UTC)

[edit] Titration/Volumetric Analyisis

Hi, could you please tell me what titration or volumetric analysis is used for in industry and in every-day life?(could you please keep the answer to a gcse chemistry level please) Thanks for the help, fv--217.22.182.30 14:56, 2 November 2005 (UTC)

You really should do your own homework. Take a look at titration and run a google search for volumetric analysis.--Screwball23 talk 19:27, 2 November 2005 (UTC)
In production in the chemicals industry, titrations or volumetric analyses are done every day in quality control labs to often check whether certain incoming raw materials meet specifications and check production batches of final products to ensure they have been made to specification. All kinds of quality control analysis methods are used, including titrations because they are fairly easy and cheap to perform. Also, water treatment facilities and other analysis labs may use titrations to check water quality or waste content. There are other uses for titrations also, such as chemical process and power plant monitoring and, of course, research. H Padleckas 19:26, 13 November 2005 (UTC)

[edit] November 3

[edit] Construction of Hale Telescope at Palomar Observatory

In November, 1947, the 200" mirror was transported by flat-bed truck(s) to Palomar Mountain. What was transpoted to the future observatory site, in a similar manner, in 1943 or 1944 or, maybe 1945? I lived in Oceanside, CA at the time and remember somethig (my memory tells me it was the mirror, but now I know it wasn't)reqiring the overhead electrical wires on Hill Street and Mission Avenue to be raised, or temporarily removed, to allow passage of the--what? My guess, now, is that it must have been the tubular housing for the telescope. Do you know what it was? I would like very much to know.

I don't have a ready answer, but the details of the construction are recounted in a highly acclaimed history of the project, The Perfect Machine: Building the Palomar Telescope by Ronald Florence. ISBN 0060926708
--Tabor 00:28, 3 November 2005 (UTC)
Poking around on the Caltech site, I found this image; it's described as "[a] huge disk of concrete and steel [that] was used [to] balance the telescope in the 1940's before the mirror was finished". It's likely that this would have been built offsite and brought in - and if it was used as a balance for the telescope, then it probably is about the same size and weight as the mirror. This page suggests that the telescope tube was on site in about 1937-8. Shimgray | talk | 01:13, 3 November 2005 (UTC)

[edit] long division symbol

My college professor swears that there is another name for the long division symbol. I have been frantically searching the internet for the answer. Every site says that there is no specific name but is a vinculum. Is there another name for the long division symbol that you know of? Help!

If he knows of one, the best way to find it out is to ask him. Mention that you've found sites, like this that say it has no name other than "long division symbol". - Nunh-huh 00:32, 3 November 2005 (UTC)

There are a number of variations on the symbols for division, but I'm thinking that the original poster is talking about the one that looks like a right parenthesis ")" with a line extending rightward from its top... right? The horizontal line might indeed be called a vinculum, but normally that word refers to a similar line with other meanings. But as to the parenthesis... in Florian Cajori's A History of Mathematical Notations it is called a lunar sign. Sometimes in short division the quotient is placed to the right and set off by a left parenthesis, like this: 16)512(32. Cajori calls this parenthesis a lunar sign as well. --Anonymous, 05:12 UTC, November 3, 2005

[edit] Mars

Where is Mars located? Name:Aidan McCarthy Age:8

Hi, Aidan!
Mars is currently about forty-five million miles from Earth, on the side of us away from the sun. Here's a diagram showing the solar system from "above"; Mars is the red dot in the upper right corner, whilst we're the blue one just beside it.
For astronomical information on where Mars is, go here and enter your location; it'll be able to produce a sky chart showing you where Mars can be seen, right now, from where you are. (Over most of the USA, it's currently in the sky to the east) Shimgray | talk | 01:21, 3 November 2005 (UTC)
Where Mars can be seen in the sky depends on the time of day because the Earth rotates around its axis, and thus the stars and planets seem to move along the sky just as the Sun seemingly moves along the sky during the day. Actiually, Mars can also be overhead during the day, but you just don't see it because the Sun is so much brighter. The same goes for the stars - they're always there, but you can't see them during the day. So over one specific night Mars seemingly moves in unison with the stars. But if you check over different nights, you'll see it moves relative to the stars. The reason for that is that the Earth and Mars also revolve around the Sun (the lines in Shimgray's first link are the orbits they follow). But they do this at different speeds. So at one moment they may be at the same side of the Sun, which is when you'll be able to see Mars in the night sky. And because Mars is in an orbit further from the Sun than Earth, it will be roughly on the opposite side of the Sun, as seen from the Earth. It is said to be in opposition then. The table at Mars#Appearance, second column, shows that in four days, Mars will be in opposition, which is the best moment to see it. It is then (and roughly now already) on the opposite side from where we see the Sun (hence the name 'opposition'), so when the Sun sets in the West, Mars rises in the East. Around midnight it will be roughly overhead (just as the Sun is at midday) and at daybreak it will set in the West, when the Sun rises in the East. About one year from now, it will be on the other side of the Sun (the last column), and then you can't see it. 'Conjunction' means that it is in roughly the same place in the sky as the Sun. So then, at midday, it will be right up there overhead, next to or even behind the Sun. It'll be there. You just can't see it. DirkvdM 10:44, 3 November 2005 (UTC)

[edit] 'Dirty Dozen' - Forensic Entomologists

Ok, so I've got Greenberg, Neal Haskell, Meek, Lee Goff, Paul Catts, Hall, Lord, Ralph Williams, and Ted Adkins. Can someone give me the names I'm missing? (Not just the last three entomologists, but first names for the ones I have.) Pretty please? DuctapeDaredevil 03:49, 3 November 2005 (UTC)

[edit] Brain damage

How come the brain can't repair itself? It doesn't make sense that nerves cells can't reproduce.

One reason I can think of is that brain cells differ from other cells in that they're not functional as 'newborns'. They derive their function from their specific connections with other nervecells. You can just produce red blood cells and inject them inot the bloodstream and they'll do their job. I can imagine that if a new muscle cell is made, it will just attach itself in a standard way. But a brain cell doesn't attach in a standard way and then function. It derives it's function from how it is attached. So it can't just be replaced. A new brain cell could only take the place of a dead one if it were to go through the exact same learning experience, which will of course never happen. So the specific memory aspect can't be restored, but that's still no reason for nerve cells no to reproduce. So I haven't really answered your question. Sorry. One answer might be that the brain starts out with an overwhelming overkill of cells to eliminate the need. The neuron article oddly doesn't seem to address this. But I believe that it has recently been found that neurons do repoduce. Anyone now? DirkvdM 10:57, 3 November 2005 (UTC)
I think the previous answer is on the right track. That is, nerve cells can reproduce, but can't really replace the dead ones, since the connections the cells had are now lost. This is why stroke victims and others with brain damage must frequently relearn language and other skills, as new cells learn the old pathways again. Why haven't we evolved a better backup system for brain damage ? Well, any duplicate system would be quite complicated, such as a redundant brain somewhere with all duplicate pathways, and would likely cause more problems than it would solve. We do have a few redundant organs, like kidneys, lungs, eyes, and ears; but most of our other organs are similarly singular. Those which do serve a redundant purpose also serve an addition function. That is, your body does better using both kidneys, lungs, eyes, or ears than with only one. StuRat 15:06, 3 November 2005 (UTC)
The nervous system is a huge network. The skeleton, for example, is a large network of cartilage and calcium phosphate (among other substances). If a connection is lost as in a broken bone, a cast could straighten or "teach" the networks the proper directions, but it couldn't replace a large quantity of the bone. Similarly, the brain does demonstrate great plasticity in that it can teach certain regions of the brain information usually restricted to another if that other region is damaged. The networks can sprout alternatively from neurons, so new axons do form. However, much of our nervous systems are developed when we are very young babies so the myelination and proper networking is usually considered complete at a young age. As we become older, our brains lose their ability to branch out and create many new neurons. The specialization of our cells leads to a very fixed number of neurons and networks, so the branching and connections between neurons will be very flexible but our ability to regenerate many new neurons is not.--Screwball23 talk 16:34, 3 November 2005 (UTC)

[edit] Bacterial Antigens

Can anyone provide a high-level list of the different types of bacterial antigens?

  • The Antigen article lists 3 types of antigens:
  1. Immunogen - Any substance that provokes the immune response when introduced into the body. An immunogen is always a macromolecule (protein, polysaccharide). Its ability to provoke the immune response depends on its foreignness to the host, molecular size, chemical composition and heterogeneity (e.g. different amino acids in a protein).
  2. Tolerogen - An antigen that invokes a specific immune non-responsiveness due to its molecular form. If its molecular form is changed, a tolerogen can become an immunogen.
  3. Allergen - An allergen is a substance that causes the allergic reaction. It can be ingested, inhaled, injected or comes into contact with skin.
However, these could be from any source, not just from bacteria, so I'm not sure that is what you are looking for.
Bacteria have proteins, Polysaccharide, and other molecules in their cell walls which can antigens. If a bacteria is ruptured, so that proteins from the interior are releases into the bloodstream, then any of these internal proteins could also become antigens. (An antigen is basically anything that evokes an immune response). There are many types of proteins, but I am not aware of a classification scheme specific to their role as antigens. One could create a high level list by including every macromolecule that is found in bacteria: cell wall proteins, cell wall polysacharides, enzymes, etc., but this list would be a somewhat subjective as to what is included. Johntex\talk 19:22, 3 November 2005 (UTC)

[edit] Southern Summer Solstice

Hello, I am trying to find the angle of the sun in Cairns at sunrise and sunset during the southern summer solstice.

Thank you, Gavin Silverthorne --203.51.205.128 11:32, 3 November 2005 (UTC)

There's a Sun Angle calculator here which might help, in conjunction with these sunset and sunrise times from the Bureau of Meteorology:
CAIRNS   Lat=-16°55'00"  Long=+145°46'00"
TIMES OF SUNRISE AND SUNSET 
(for ideal horizon & meteorological conditions)
Time zone: +10.00 hours
21/12/2005  Rise 0541  Set 1849

--Canley 23:53, 3 November 2005 (UTC)

[edit] Corn cob

What is the scientific reason behind the fact that the number of columns of seeds in a corn cob is always even ?

Many plants exhibit regular patterns in the growth of their leaves, seeds, and buds. The sunflower, for example always grows new seeds at the end of a spiral growing outward. Stems branch out in regular patterns as well in certain plants. The seeds on a corn cob would probably be the result of a regular phyllotaxis of the seeds. That would show why they grow in their regular patterns but the even numbers is more mathematical. The phyllotaxis of many plants does follow regular mathematical precision, which has been graphed and mapped by many scientists, but I'm not sure on the specific reason. Check and see.--Screwball23 talk 16:17, 3 November 2005 (UTC)

I'm not sure, but I would guess that it is due to nature's preference for bilateral symmetry. This is a handy trick for reducing the number of instructions required to "build" and organism. A bilatrally symmetric corn cob will always have an even number of seed rows, because the instruction is (basically) "build one seed row on each side". Physchim62 (talk·RfA) 11:46, 4 November 2005 (UTC) Do any body else know more logical reasons ?

[edit] Electro Ceramics

Does porosity have any advantages on ferroelectricity & pyroelectricity & piezoelectricity? and what are those advantages? That would be very kind of you to answer me, with the best regards, F.KashaniNia

I don't understand the question. Can you clarify it please ? StuRat 05:40, 4 November 2005 (UTC)

[edit] A name of a reaction

What is the reaction called that happens when an acid is turned to an alkali using sodium hydroxide?

Lucas 12

[edit] Zinc

Is Zinc difficult to extract from its ore?

Lucas 12

  • According to our article on Zinc: "Zinc metal is produced using extractive metallurgy. Zinc sulfide (sphalerite) minerals are concentrated using the froth flotation method and then usually roasted using pyrometallurgy to oxidise the zinc sulfide to zinc oxide. The zinc oxide is leached in sulfuric acid and the resulting solution is purified using zinc dust. The metal is then extracted by electrowinning as cathodic deposits. Zinc cathodes can be directly cast or alloyed with aluminum. Another process to produce zinc is flash smelting, a pyrometallurgical process. Then zinc oxide is obtained, usually producing zinc of lesser quality than the hydrometallurgical process. Zinc oxide treatment has much fewer applications, but high grade deposits have been successful in producing zinc from zinc oxides and zinc carbonates using hydrometallurgy." Johntex\talk 21:00, 3 November 2005 (UTC)

[edit] tidal energy

How easily can tidal energy be adapted tot he lifestyles of average canadians?

Canada has a rather large land area and small population, so could benefit from a wide range of alternative energy forms, like wind, solar, and hydroelectric power, which wouldn't be very useful to a country with a higher population density, like Singapore. StuRat 05:35, 4 November 2005 (UTC)

The only lifestyle change tidal power really requires is the preparedness to spend a great deal more for electricity than that generated by alterantive sources. --Robert Merkel 08:18, 6 November 2005 (UTC)

[edit] Earth sciences, naming and history.

I have talked a little about this on the talkpage of Earth science, the question is basically: Who named this science and why? The reason I ask, is because I think this is bad naming and here is why:

  • Geo-logy basically means the same thing as earth-science. Science is Latin for "knowledge", logy is Greek for "Word", both words have been used widely to describe professions that "study things". Ge(o) means The Earth, and is Greek also. Imagine using a name like terralogy and geology, not as synonyms. It is perplexing.
  • From a historic view, I think, geology is obviously supposed to be the "all-embracing term for the sciences related to the planet Earth." Geology may have started with the study of rocks, but the study of rocks gave us understanding of the inside workings of the Earth, that had been hidden from us. Then we see, how the inner part of the Earth interacts with the outer part, which we have studied somewhat longer, because of accessibility. This all effects the Earth, the fusion inside it and the weather outside it. Realization of this, should have expanded the definition of Geology, not made it a subcategory. A subcategory of itself infact :P

Geology (earth science) is fairly new to us, so I guess this is to be expected, but no one seems to know why the naming is like this or the reason behind it. Hope someone can help, thanks. --Friðrik Bragi Dýrfjörð 20:33, 3 November 2005 (UTC)

Geo does not mean Planet Earth. It means a piece of earth (ie: a rock or some soil). Therefore, geology is the study of rocks and soil. Earth Science (which I used to hear referred to as Natural Science) is the set of sciences that study the planet (such as meteorology). Kainaw 21:38, 3 November 2005 (UTC)
According to the Geology article, it means "the earth". Just as in Geography (notice, Earth is written with capital E). So I do think you are wrong. Please, also note, that Earth science is also called geoscience. --Friðrik Bragi Dýrfjörð 23:45, 3 November 2005 (UTC)
Geo comes from the Greek work ge (the "o" is used for the conjunction with the suffix). It means rock or soil. The Greek word Gaea means "planet Earth". While both start with a "g" and have an "e" in them, they are not similar in a Greek sense (even "Greek" has a "g" and "e" in it). So, it is a bit of a stretch to assume ge and Gaea are interchangeable.
Ignorance about ge has led many to think that it is the Greek word for our planet. (I said ignorance, not stupidity. I mean that many people just don't know Greek.) So, geo has been abused with improper words, such as geoscience. It is similar to the use of virii. With a basic understanding of Latin, you would know that virii is in no way a plural form of virus. If enough people use it incorrectly, the incorrect use will become correct. For example, the word "ain't" is now in most dictionaries even though any English teacher will tell you that it is incorrect. Kainaw 00:33, 4 November 2005 (UTC)
Thank you very much, this will also help me with a problem in my language. I checked dictionary.com, and is says there, "[Medieval Latin gelogia, study of earthly things ...]", so I still think this is very confusing. Surely, "study of earthly things" sounds as broad as "earth sciences". Perhaps I am being too picky :-) --Friðrik Bragi Dýrfjörð 01:33, 4 November 2005 (UTC)

Geology is often associated (rightly or wrongly) with the study of rocks, so the terms earth sciences was coined (in the 1960s or 1970 I think) to include the study of rivers, oceans (oceanography), the atmosphere and the other natural phenonmena which impinge on a planet. Physchim62 (talk·RfA) 11:51, 4 November 2005 (UTC)

It might also be useful to consider it this way - in the sixties and seventies, "planetary science", the study of all things relating to a single planet, was becoming a seperate discipline for the first time, with enough work done to make it more than a branch of geology (geologists are fine for the moon, but once you're looking at anywhere else you have atmospheres and so forth to contend with) - "earth science", the study of all things relating to this planet, is a logical corrolary. Shimgray | talk | 12:53, 4 November 2005 (UTC)

[edit] Frequency of eye colors in the US

Hi there! I'm looking for information on relative frequency of eye colors in the USA, specifically the pacific northwest if that information is available. For example, what are the 10 most common eye colors? In what order? This is tricky, as my research has shown me that eye color is often a racial trait, in the sense that people of one descent might be much more likely to have one eye color than people from elsewhere. I've read the Eye color article, as well as googled all over, but if this information is available somewhere, I'd love to have it. If anyone has any ideas on where to look further, I'm happy to do the work, I just want the info and have run out of search ideas. Thanks! - CHAIRBOY (☎) 23:23, 3 November 2005 (UTC)

[edit] hexagons

I am looking for the formula to determine the size of a hexagon that could be stacked to cover a particular sphere size

Your question is too vague. What do you mean by "stacked to cover"? You could take one hexagon and wrap it around a sphere. You could take a grid of them. To make a real sphere without warping them, you'd need pentagons too (like a Bucky Ball). Kainaw 23:40, 3 November 2005 (UTC)
  • When Kainaw mentions a "Bucky Ball", he is referring to Fullerene. Our article on Fullerene states

"In mathematics, a fullerene is a trivalent convex polyhedron with pentagonal and hexagonal faces. Using Euler formula, one can easily prove that there are exactly 12 pentagons in a fullerene. The smallest fullerene is C20, the dodecahedron. There are no fullerenes with 22 vertices. The number of fullerenes C2n grows rapidly with increasing n = 12,13, ... For instance, there are 1812 non-isomorphic fullerenes C60 but only one of them, the buckminsterfullerene alias truncated icosahedron, has no pair of adjacent pentagons."

The term "Euler formula" is referring to one of the formulas of Leonhard Euler. However there are several at Euler function (disambiguation) and it is not immediately obvious to me how any of them relate to this quesiton. As Kainaw says, some clarification of your question would be helpful.
From Leonhard Euler: there is a relationship (also called Euler's Formula) which relates the number of edges, vertices, and faces of a simply connected polyhedron. Given such a polyhedron, the sum of the vertices and the faces is always the number of edges plus two. i.e.: F - E + V = 2. I am prety sure that this is the formula mentioned. From this fomualr one can determine that a convex simple polyhedron composed mostly of hexagons must always include 12 pentagons. If a ployhedron had all of its faces as hexagons, E=6F/2 (since each edge is shared by two faces) and V=6f/6 (since eaxh vertex is shared by six faces) so F - (3F) +(F) = -2F, which violates the rule F - E + V = 2.
Also i thgink that strictly speaking "fullerene" is the term for a carbon molecule with one of these shapes, NOT for the abstract mathematical shape itself. DES (talk) 02:00, 5 November 2005 (UTC)
If you are trying to ask "For a sphere of a given size and a certain number of hexagon's how big would the hexagons need to be to cover the sphere?"
If so, then you might like to know that the surface area of a sphere of radius r is: A = 4 \pi r^2 \,
The area of a regular hexagon of side length a\,\! is given by A = \frac{3}{2}a^2 \cot \frac{\pi}{6} = \frac{3 \sqrt{3}}{2}a^2 \simeq 2.59808 a^2.
The area of a regular pentagon with side length a is given by A = \frac{5a^2}{4}\cot \frac{\pi}{5} = \frac {a^2}{4} \sqrt{25+10\sqrt{5}} \simeq 1.72048 a^2


You might be able to derive a formula to figure out from this how big the hexagons and pentagons would need to be, given the size of your sphere. Keep in mind that the length of the side of the hexagon will be the same as the length of the side of the pentagon.
If what you want to know is specific to the case of the dodecahedron, then that article shows that the area A and the volume V of a regular dodecahedron of edge length a are:
A=3\sqrt{25+10\sqrt5}a^2
V=\begin{matrix}{1\over4}\end{matrix}(15+7\sqrt5)a^3
See also Polyhedron, Polygon, and Geodesic dome. Good luck, Johntex\talk 00:43, 4 November 2005 (UTC)

You might want to read the artcile on geodesic domes. Hexagons form a planar pattern, so a series of triangles are typically used in dome design. StuRat 05:28, 4 November 2005 (UTC)

[edit] November 4

[edit] paternity about ABO blood groups

case with mismatching ABO blood antigen in parents and one of their offspring the father is O+ ,mother is A+ and the daughter is B+ if it is possible I want to know the chances and possibilities is it mutation , or what because the girl lock gust like her father.

Maybe you should check the blood type of the "father's" brother then ? StuRat 05:07, 4 November 2005 (UTC)
I'd advise against jumping to conclusions until you've discussed this with a real genetics expert. Genetics is a lot more complicated than many people think. Andjam 13:08, 4 November 2005 (UTC)

[edit] Universe Expansion and Contraction

I just read an article concerning the possible discovery of a supermassive blackhole at the center of our galaxy. And that sparked my curiosity about wether our galaxy is expanding or contracting?

I know that all galaxies of the universe are moving away from each other, Expanding, at equal speeds, and that as a whole the universe is in fact expanding. But then there are blackholes, such as at the center of our galaxy, that are so dense with matter that the gravitational force is pulling in surrounding planets and stars like a cosmic whirpool. This would be a form of galactic contraction, right?

Also where does the matter and energy go? Scientists say that it completely disappears, because no light can escape a blackhole. Could these be the sites of new universes, turning the dimensions inside out to create new alternate, and invisible (to us) worlds?

I would enjoy any guesses or information you may have.

thanks- brian

In this area of physics, you will find all kinds of nutty theories (I even wrote a whole paper to disprove that gravity exists). The universe is assumed to be expanding because we are moving away from most things and most things are moving away from us. If everyone is moving apart, it must be expanding. The issue is: how do we know we are moving apart?
Where does the matter and energy go? Well, matter and energy are different forms of the same thing (like ice and water). That's how we get nuclear power. So, where does the goop go? The latest theories are that it is broken up and emitted as X-ray energy around the edge of the black hole.
Also, the black hole doesn't suck everything up. Matter that is far enough away will be affected by it, but not sucked up. Kainaw 00:52, 4 November 2005 (UTC)
I'm not completely sure what Kainaw means, by "broken up and emitted as X-ray energy", but I think he might be referring to Hawking radiation, which I neglected to mention in my answer below. That's yet another answer about what happens to stuff in black holes, it eventually comes back out. (However, for a black hole with more than the mass of the sun, "eventually" means something like 1050 times the current age of the universe.) -- SCZenz 01:23, 4 November 2005 (UTC)
There are three separate issues you bring up. One is the expansion of the universe, which you can read about in the Dark energy article; it's actually mostly unrelated to the behavior of black holes and the dynamics of the galaxy, so I won't discuss it further for now. (But of course I'll give it a shot if you ask more questions.)
The second is whether the galaxy is contracting because of the big black hole in the middle. The answer, I believe, is that if it is it's doing so extremely slowly. Most of the stars in our galaxy are in stable orbits around the center, and won't collapse into the center any more than the earth will fall into the sun.
The third is what happens to stuff that goes into a black hole. One answer is that, from the view of an outside observer in the universe, things falling into a black hole will take an infinite amount of time to even fall through the event horizon; it's strange, but true. Thus, wherever the stuff that falls into a black hole goes, it isn't there yet. Another answer is that it just sits at the center, as part of the singularity. A third answer would be that, well, we have no idea and there's no way to find out. It's hard for physicists to make predictions about things we can't possibly verify experimentally.
I hope that helps. Ask more if you've got more questions or need something clarified. -- SCZenz 01:20, 4 November 2005 (UTC)

Just to simplify the answers on black holes affecting expansion or contraction of the universe...as massive as black holes in the center of galaxies may be, they are a tiny portion of all the mass in the universe, and thus don't have much effect on the expansion or contraction of the universe. Also, whether the mass was evenly distributed or in a series of black holes might not make much difference in the calculations, if the total mass is the same. The oddest thing about the expansion of the universe, is that it seems to be expanding at an ever increasing rate. This requires some exotic theories to explain. StuRat 05:17, 4 November 2005 (UTC)

I started a related thread a while ago. This is one such exotic theory to explain the accelerated expansion of the universe. The idea is that as one accelerates towards a black hole (or any other mass) everything else appears to be accelerating away from us. But we won't notice that we are falling into the black hole (or whatever) because for an outside observer we may be taking an infinitely long time, but for us, time is passing normally (it is our framework, so we can't observe it otherwise). Same for being stretched out; that is only true for the outside observer, but for us, again it's our framework and all seems normal. Which is a wrong way of putting it. Since it's our framework it is by definition normal for us. But that's only true for local events. As we observe things farther away we see the effect more and more. I'm still looking for a better way to explain this.
In this light the remark that the mass of black holes is too small (relatively) to affect the universe as a whole seems a problem. But I see two ways out. One is that the effect is only local; since we are falling into the black hole it is part of our framework and we don't see it as a black hole. So it's not the one at the centre of our galaxy, it's a black hole we don't see. The other is that the mass of the universe itself (as a whole) could have a similar effect. Since masses' attraction to each other is acceleration, the whole universe accelerates towards itself. I'm trying to envision a similar expansion and contraction because (that was my first problem) the size of the universe should be considered an immeasurable constant.
I am now moving my index finger up and down my lips, making funny noises. This kind of stuff drives me nuts. DirkvdM 10:11, 4 November 2005 (UTC)
Dont forget the Wimper theory. A British Astrophysist ( due to more research on the subject, two promoniant British Astrophysists workd on this together, Fred Hoyle and Chanandra Wikramnschmingle ) solved Einstiens' equations, using the size of the universe as constant, and found no contradictions. This is called the Wimper Theory, in that the size of the Universe is fixed, but we are all getting smaller, and the speed of light is getting slower. Hoyle are more commonly known for the Steady State Theory:

Fred’s contribution to cosmology is what he was best known for by the general public. In 1948 he, and Bondi and Gold, in two separate papers (Hoyle 1948; Bondi and Gold 1948), put forward the idea that the Universe is in a steady state. Fred’s contribution was the introduction of an extra term Cµν into the Einstein field equations. This extra term represents the creation of matter. At least initially the form in which matter was created was not specified, although of course it had to be electrically neutral. More recent theory, which explains the isotropy and homogeneity of the Universe, namely the ‘inflation’ theory, has a metric which is identical to that of the C -field cosmology.

There is some very recent discussion about the effect of gravity on very, very large objects, and the implications of M-Theory on the glactic rotational constant. But back to your question:

Regardless of the presence of a black hole at the center of our Galaxy, both the Universe ( everything we detect ), and our local cluster ( us, and nearby galaxies), and us ( the Milky Way Galaxy ) is expanding, evidensed by the observation of the redshift. ( light emissions shifted toward longer red wavelengths due to doppler shift ). The cosmological question is what will the end look like, and gives rise to 3 1/2 theories:

  1. Expanding: The Universe will expand forever.
  2. Oscilating: The Universe will expand until heat death, then something will cause it to contract into a single mass, and a repeat of the big bang will happen.
  3. Steady State, New Matter is being created at the center of the Universe, and it is constantly replenishing itself
    1. There is a new theory called 'BBN' for Big Bang Never Happened. [[6]] and it has critics: [[7]]
    2. Wimper Theory. ( Not serious, but still a consideration ). The Universe is a fixed size, and everyhing is getting smaller.

Note: This is an extrodinary refrence: [Cosmology FAQ ]

"Tell your Congressman and Senators to support astrophysics research at NASA, NSF, and DOE."

Artoftransformation 12:43, 4 November 2005 (UTC) Updated 03:08, 9 November 2005 (UTC)
I wanted to update this today with a quote from one of my sources:

"The original S-S universe and its more recent successors all posit a universe that is infinite in extent. The expansion everywhere is compensated by episodes of creation (mini bangs in recent models) so as to maintain an overall SS state. The velocity of light is constant."

- Chandra Wikramnschmingle, Director, Cardiff Centre for Astrobiology, Cardiff University


I'm reminded of a lengthy reference desk discussion I started some time ago. User talk:Eequor/Reference/Event horizons may interest you. ‣ᓛᖁ♀ᑐ 13:06, 4 November 2005 (UTC)

When searching for the wimper theory all I found was the 'big whimper theory' (with an 'h'), so I suppose you mean that. But all I find on that (which is not a lot) says it means the universe will keep on expanding and die out, the first item in your list. Did you accidentally use the wrong term? The last result of a Google search gave me a name too, Michael D. Lemonick. (Senior Science Editor at Time Magizine, worte a book called 'Echo of the Big Bang' ). No article on him either. If this 'everything getting smaller in a fixed-size universe'-thing has already been proposed as a theory I'd love to read more about it. It's a bit frustrating that whenever I come up with some wild idea it turns out to have been thoght of by someone else. But the up side is that it's an indication that I'm not as much a nutter as some around me seem to think. :)
The site you read from Google, [[8]] about the Wimper theory is not what Sir Fred Hoyle and Chandra Wikramshmingle theorized. I completed two years of College Phsysics, and Eeqors article is hard to follow. I was sick in bed, but my mind is sharp as a tack.
I would point out, that if you come up with an ingenious idea, independant from others, your timing is bad. If you come up with the idea later. They get the Nobel Price. If you come up with the idea simultaiously, then you sare the Nobel Prize. Richard_Feynman "For his work on quantum electrodynamics, Feynman was one of the recipients of the Nobel Prize in Physics for 1965, along with Julian Schwinger and Shin-Ichiro Tomonaga." If you come up with the idea first: Write a Wikipedia Article. Artoftransformation 04:36, 9 November 2005 (UTC)
Eequor's article looks interresting too, but I'm no physicist and find it hard to follow (and I had a party last night, which doesn't quite help - I'll read it in more detail tomorrow). It does, however, mention something I hadn't gotten into yet. If you're falling towards an attractor (be it a black hole or the centre of gravity of the universe (if there is such a thing)) then what is closer to it (exactly dead ahead) has at that moment already accelerated more and what is 'behind' you has accelerated less, so both seem to accelerate away from you. But what about what is next to you? When close by the (now much smaller) effect is overwhelmed by local movement. But whatever is further away and not dead ahead will be 'forced back', appearing behind us and also accelerate away, at least from an outside observer's reference frame. To us it will appear to be all around us. But I'm really out of my depth here and may be completely misinterpreting what I've heard. Theresa Knott says "at right angles to these directions galaxies would appear to be moving towards us". That one puzzles me. DirkvdM 12:49, 5 November 2005 (UTC)
Spaghettification
Oh, that's due to spaghettification. Since the circumference of a circle decreases with decreasing radius, objects at the same distance from the black hole must become closer together as they fall toward it. ‣ᓛᖁ♀ᑐ 20:07, 8 November 2005 (UTC)
Great visual. If you drop a pebble from the leaning tower of piza, one a second... you will see, that the further pebble is moving faster than the nearest pebble, while under constant acceleration. ( increasing velocity, and acclerating distance ). This is simple first semister Physics. If your falling towards a black hole, the frame of refrence is translated, and the objects closer to the black hole, appear elongated. "paghettification". Artoftransformation 04:47, 9 November 2005 (UTC)
Ah, but again, that's from the perspective of an outside observer. For who-ever is accelerating this is the frame of reference. It's their frame of reference that contracts sideways, so they don't see it as a contraction. Right?
Also, by Artoftransformation's explanation it's relative. Space gets stretched out lengthwise. The sideways contraction is only relative to that. Right? Well, I suppose that since it's relative you might as well say that the lengthwise stretching is another way to express the sideways contraction. Taking one of these two options is simpler than a bit of both (simpler equations, I suppose) and therefore 'more true'. DirkvdM 10:13, 9 November 2005 (UTC)
Hm, I'm not sure. The perceived acceleration will at least be very much less laterally than radially.
...The observed distance around the black hole will still decrease, regardless of whether the observer is falling in; otherwise, the singularity must be a circle of some fixed size, not a point. The faller simply has the most precise view of how large that distance is. ‣ᓛᖁ♀ᑐ 12:58, 9 November 2005 (UTC)

[edit] Upload and download content on a website

Hi -

I'm creating a new website, and I want to have a section where people can upload and download source code and files, kind of like SourceForge.net. Are there any free resources/templates/guides or whatever that can show me how I could do this?

Thanks! Mary

GNU Savane is the software that the GNU Savannah [9], GNU's SourceForge-alike, uses. — mendel ☎    #    01:21, 4 November 2005 (UTC)

[edit] Center of mass/gravity/inertia

Which two of these is the same thing?

  • Center of mass
  • Center of gravity
  • Center of inertia

After you have answered, see Talk:Center of gravity#What's the difference?. — Omegatron 02:44, 4 November 2005 (UTC)

I have heard center of mass and center of gravity used equivalently, and I've never heard of center of inertia at all. That being said, people should be aware that terms like this are not always used uniformly, and that they may mean different things in different texbooks. -- SCZenz 02:48, 4 November 2005 (UTC) (P.S. Why the template for the signature? I've subst'ed it to reduce server load, but what's wrong with ~~~~?)
if gravity isn't uniform (which really it isn't) I don't think CoG = CoM. I've never heard of center of inertia, so maybe its the same thing as CoM. Broken S 02:59, 4 November 2005 (UTC)
Interesting. In what situations is CoG, as different from CoM, used? -- SCZenz 03:03, 4 November 2005 (UTC)
I'm not sure. I have a good book I'll look it up in. (or I'll ask my phy prof) Broken S 03:12, 4 November 2005 (UTC)
Yes, CoM is different from CoG in a non-uniform field. I trust that. I don't know which of these is equivalent to CoI, though. — Omegatron 03:09, 4 November 2005 (UTC)
Okay, my book confirms the Com != CoG (except constant g) but doesn't list CoI. I've never heard of it. You sure anyone seriously uses it? Broken S 03:18, 4 November 2005 (UTC)
Ohhhhh... I didn't know that. Only 586 hits, vs 1.7 million for the other two. But the center of mass article lists it in the first sentence, so we need to at least make it correct. — Omegatron 03:23, 4 November 2005 (UTC)
Some would say that centre of mass is ambigous, as one should specify whether one is referring to gravitational mass or inertial mass—however, as the two are at least nulerically equivalent (if not identical, depending on your theory) the distinction is rarely, if ever, important. Physchim62 (talk·RfA) 11:59, 4 November 2005 (UTC)

Are you sure you don't mean Moment of Interia? Dominick (ŤαĿĶ) 01:19, 5 November 2005 (UTC)

[edit] Photosynthesis Questions

Photosynthesis creates glucose and O2 from Co2 and H20. What exactly is the role of chlorophyll? Can chlorophyll be created in a lab? Can this molecule carry photosynthesis out on its own? What are the most basic things required to conduct this process? Can bacteria code for a plant's photosynthesis genes?

Thanks to all who try to answer.

  • Chlorophyll isn't the only thing that's needed for photosynthesis. A plant also uses several enzymes for this. I'm sure it can be created in a lab. All you need to do is clone the chlorophyll producing gene into a bacteria and isolate it. Whether bacteria with chlorophyll expressed are viable and remain alive after transfection, I don't know. - Mgm|(talk) 09:11, 4 November 2005 (UTC)
    • Chlorophyll is required to capture the light, which provides the energy needed for photosynthesis. This energy is passed through a series of molecules known as a photosystem (there are two distinct photosystems in green plants which work in tandem). When chlorophyll is extracted from a plant, it still absorbs lights but cannot pass the energy down the photosystem: in fact, it picks up so much energy that it decomposes, and isolated chlorophyll must be stroed in the dark. Photosynthesis in plants occurs in specialised organelles (subunits of the cell) called chloroplasts: these were undoubdtedly once free-living bacteria (about 3 billion years ago): many of the genes required for photosynthesis are coded on DNA contained within the chloroplast itself rather than in the cell nucleus. Some living archaea can photosynthesise without using chlorophyll, and water can be split into oxygen and hydrogen (the basic reaction of photosynthesis) by amorphous silicon. I hope this answers some of your questions, even if it gives you even more in return! Physchim62 (talk·RfA) 12:09, 4 November 2005 (UTC)
  • When you ask about created chlorophyll in the lab and whether bacteria can code for the plants sphtosynthesiis gene[s], I think you may be asking whether bacteria can be used to express plant chlorophyll. Please see cloning, genetic engineering, and protein engineering. Good luck! Johntex\talk 17:00, 4 November 2005 (UTC)

[edit] Births & the seasons

In my office people bring in cakes when it is their birthday. I've noticed that there are a lot less birthdays (& cakes) in autumn & winter than in spring & summer. As birds & animals aim for their young to be born in spring do humans (subconsciously perhaps) do the same thing? That is in practice are there actually more births in spring & summer then autumn & winter? Thanks AllanHainey 08:41, 4 November 2005 (UTC)

  • In the United Kingdom, there is usually a peak in births in late September and early October: in Glasgow this is called the "Hogmanay" effect... Physchim62 (talk·RfA) 12:12, 4 November 2005 (UTC)
  • There's all sorts of factors that can affect community birth rates. Your observation might be similar to the blackout effect: there's not much else to do in a blackout — or when trapped inside by winter weather. So I'm not sure that it's a subconscious effort so much as a result of when people have more time on their hands. — Laura Scudder | Talk 20:44, 4 November 2005 (UTC)
    • This web page includes a table of birth rates in different months in the US, based on data from the years 1978-87. The highest birth rates are not in spring and summer, but rather in summer and fall, specifically from June to October with the highest rate in September. But the variation is only about 6% above or below the mean, so it's not "a lot" more or less in any case. --Anonymous, 11:10 UTC, November 5, 2005
    • Incidentally, the blackout effect seems to have been fictional - [10]. Shimgray | talk | 15:49, 5 November 2005 (UTC)

My mother was born exactly 9 months after the repeal of Prohibition. I think grandma and grandpa got good and drunk and then... StuRat 18:31, 5 November 2005 (UTC)

[edit] Weather Report Archives

HI!:D

I am a writer and past weather reports frequently comes up in my stories.

Is there a site where I can find archived weather information from the 1900s and on?

Thank you!:D

Kevin Conner

You might have to be more specific. For what region/city/country etc do you require the information? Akamad 10:36, 4 November 2005 (UTC)
NOAA maintains the National Climatic Data Center, which may be what you have in mind. See [11] and [12]. ‣ᓛᖁ♀ᑐ 01:19, 5 November 2005 (UTC)
  • If you are looking for day-by-day, locale-by-locale reports, in my experience, if you don't want to shell out big money, your best bet is looking at newspapers from that region at the time you are looking for. The NDCD has a number of reports online though time coverage is sketchy. --Fastfission 01:10, 7 November 2005 (UTC)

[edit] Thermal expansion of tram rails

It's something a friend's son asked the other month, and is intriguing me. Tram (streetcar) rails never seem to have expansion joints, so why don't they buckle when the sun is hot? TobyJ 11:33, 4 November 2005 (UTC)

San Francisco's BART uses a continious weld rail system.
See: [Continuous welded rail]

Artoftransformation 12:10, 4 November 2005 (UTC)

The rails are under tension by stretching. This means that as the rail expands, it remains the same size but becomes less tense. Of course, if the weather gets too hot or cold, the track will still snap. smurrayinchester(Penny for the Guy?), (The Guy) 12:57, 4 November 2005 (UTC)

[edit] Sabre F86 fighter plane used during Korean War

I am an author and I am writing a young adult novel where the father of the family is flying over the Yellow Sea in December 1952 and is shot down by enemy fire. He is quickly rescued by a fisherman from one of the 3000 islands there.

I wanted him to suffer burns on his legs, nothing too serious so that her would be able to survive with the help of the Island people until found. If the plane was hit in the side, could a fire start in the cockpil and cause him to Parachute out? WOuld his ejection seat work?

I would like to know what would his actions be after his plane is hit. What instruments would he have to engage before opening his parachute? If this were a movie, what exactly would he be doing, or possible be doing?

I do appreciate your help.

SIncerely, Adele Aron Greenspun

Mentally, due to the rush of adrenalin, everything would speed up giving the impression that time had slowed. He would instantly feel the loss of control of his aircraft. His mind would not “think” of anything. His training would kick in and he would proceed with the ejector seat drill. If he gets that far he is unlikely to burn but he would probably suffer limb damage as ejecting from fighter aircraft was a bit risky in those days. You say you are writing a story? Sit in a chair in a quite room with your eyes shut and just imagine what it must have been like. Then write. :-) --Eye 19:53, 8 November 2005 (UTC)

[edit] Computer on the fritz

I know I should take this in, but I'm wondering if any of the bright bulbs here have any thoughts first.

I've got a 1-year old Fujitsu-Siemons laptop running XP. Recently (in fact, shortly after being fixed under warrenty for a motherboard replacement) it's been having two problems:

  • First, the computer will preiodically freeze. By freeze I mean completely frozen:
    • No mouse movement
    • No Ctr-Alt-Del response
    • No turning off the screen when laptop is closed
    • Fan and screen stays on
    • No response at all until I force it off by holding down the power button
    • If, after turning it off like that, I turn it on again too shortly (<10 minutes), it is very liable to re-freeze immediately after turning on
    • That last point made me think that it was over-heating, but I've cleaned out both fans, which seem to work fine, and my room is quite cold
    • This happens even if only one (as far as I can tell) program is running
    • For instance, it just froze as I was typing this, and it had been on for less than five minutes, running only firefox
  • Second, more recently, it will sometimes not turn on fully:
    • I hit power and the LEDs turn on and the fans wirr up, but the screen doesn't turn on and I don't hear the start-up beeps and jingles, nor any hard drive action
    • This often happens multiple times in a row

Any of this sound like a familiar set of symptoms? Any help very much appreciated...
— Asbestos | Talk (RFC) 15:37, 4 November 2005 (UTC)

I think you're on the right track with it overheating. Perhaps the fan is malfunctioning in some way, such as if it is covered with a piece of paper they left inside during construction. Does there seem to be a nice breeze coming out of it ? I just had a problem with a ribbon cable interfering with the fan movement on my PC. You might want to open up the case to see if anything inside seems to be blocking or interfering with the fan. Also, try aiming a regular fan at the PC to help keep it cool, and, of course, make sure it has proper airspaces on all sides. You can also put it on a metal stand so the bottom will cool off nicely. StuRat 22:05, 5 November 2005 (UTC)

My first laptop was one of those foojitsoo thingies. One day it froze and would not switch off. Unlike a desk top you can just pull the power lead out, with this thing it took me a while to think about pulling the battery out...duh! Anywhy I had very little trouble from it once I had wiped the bundled crap out of it and did a clean boot with xp. My son had it for college where he proceeded to feed it beer and crisps. It still works dispite his best efforts. Japs and Germans eh! Makes you wonder who realy won the war.--Eye 22:17, 4 November 2005 (UTC)

Something else you can try - buy a small can of compressed air (cost about $4 - you can get it from any computer shop) and blow through the grilles on your laptop to clear any dust that may have settled there, clogging your airways (I have to do this every 6 months on my laptop otherwise it overheats). To check if overheating is really your problem, download a utility that allows you to check the temperature inside your computer. Your BIOS may be able to do this (hit DEL or F1 or something when your computer starts up), or else search around the internet for a program. Good luck! — QuantumEleven | (talk) 10:17, 7 November 2005 (UTC)

Very, very rarely, I have a similar problem with my laptop with symptoms almost identical to that of your first problem. That is, complete freeze, light doesn't go off when lid shut, absolutely no response etc. I've tracked down the problem to a faulty audio driver. However, the problem only occurs when I'm doing a lot of audio-related stuff, particularly when using VoIP programs (Google Talk is especially erratic with this error when in call mode). The only option is to shut it off by holding the power button. So maybe there's a problem with one of your drivers? Investigate them, it may help. -- Daverocks 09:26, 10 November 2005 (UTC)

[edit] LCD interview

I am interested in LCD and was wondering if i could set up a interview either in person over the phone or on the internet? I am sorry that i posted this here but i could not find anyone to email thank you.--64.160.211.191 16:49, 4 November 2005 (UTC)

Actually we are an encyclopedia, not a recruiting agency, so we probably can't help. Not knowing who LCD are is also a disadvantage. I suggest searching the web for LCD until you find the website of the company you are interested in. That will give you contact information. DJ Clayworth 17:39, 4 November 2005 (UTC)
I didn't even know Liquid Crystal Displays were hiring. StuRat 22:18, 5 November 2005 (UTC)
Would this be suitable for BJAODN? -- Daverocks 09:29, 10 November 2005 (UTC)

[edit] physics\relativity

In the degree level textbook of physics,in order to explain the time dilation, the example of light clock(which tixks when an emitted light reaches a mirror and comes back)is given.That clock when moved at a speed comparable to that of light ticks slowly.But how an electronic or atomic clock ticks slowly when moved along with the light clock as it's working is based on the piezo crystal or some thing like that?Also how the twin paradox occurs?

How the clock works is completely irrelevant. The laws of physics are the same in any inertial reference frame, so if it works on earth, it'll work when moving away from earth at high speed too. Perhaps the fact that the speed of the clock is "comparable to the speed of light" and the light moves at the speed of light is confusing; if so, reading about relativity's velocity-addition formula might help. As for the twin paradox, you can read twin paradox.
It might help most of all to start with Special relativity for beginners. Hope that helps! -- SCZenz 18:28, 4 November 2005 (UTC)
  • To make things clearer, all physical processes are affected by time dilation. So not just light clocks, but all clocks, and everything else that takes time - atoms decaying, eggs cooking, humans ageing, everything. I think one of the reasons light clocks are used in teaching is because you can use them to derive the Lorentz-Fitzgerald contraction, etc., given the two postulates of SR. --Bob Mellish 20:33, 4 November 2005 (UTC)

[edit] .pst files in Thunderbird

I am trying to convert an Outlook .pst file (I only actually want the email messages from it) into Thunderbird (although I don't really care, so long as I can read them. Thunderbird says it can convert Outlook pst files, but only if Outlook is installed. Do I have any other options? I don't have Outlook. Thanks, Trollderella 19:35, 4 November 2005 (UTC)

Maybe not very useful, but I'm afraid the answer is no (also see vendor lock-in). --R.Koot 22:49, 4 November 2005 (UTC)
You might want to take a look at [13]. It doesn't work with Outllok 2003 files though. --R.Koot 12:18, 5 November 2005 (UTC)
Woah! Thank you! That could be it! Damn you Bill Gates! Damn you!! Trollderella 16:48, 7 November 2005 (UTC)

[edit] How do they make rice noodles?

I bought some Thai rice noodles the other day. They're really good if you cook them right, but they kinda freak me out because the box says "Ingredients: rice flour, water." and I have no idea how it's possible to make noodles out of just rice paste with nothing to hold it together (like egg or something). What's the magical secret to making them? —Keenan Pepper 20:41, 4 November 2005 (UTC)

You are referring to pancit. Normally, they are made with rice flour and water, just as the box said. The Chinese that I know tend to add eggs, but that is because they prefer egg noodles. I'm sure the Thai would complain that the egg noodles are not rice noodles. Kainaw 20:54, 4 November 2005 (UTC0

What do you think is in spaghetti or`pasta?--Eye 22:22, 4 November 2005 (UTC)

There is more than enough starch in rice to make it sticky enough to make noodles. Trollderella 23:59, 4 November 2005 (UTC)
Indeed — starch (such as flour) and water alone make a very sticky paste. Think papier-mâché paste. Also, when I used to make labels for my homebrews, a little milk on the label worked as strong as any glue. — Asbestos | Talk (RFC) 00:40, 5 November 2005 (UTC)

When I make homemade pasta I use flour and for liquid I use eggs, milk, water, or even vegetable juices mixes for color. ANy flour does the trick, even whole wheat. It is a simple thing, watch someone do it ONCE and you are an expert. Dominick (ŤαĿĶ) 01:15, 5 November 2005 (UTC)

People use rice and water to make rice noodles. This is the way they make rice noodles in Taiwan:
  1. Buy rice (better aged for 3-6 months) that is not too glutinous. Some breeds are specially developed for making rice noodles.
  2. Soak your rice in water.
  3. Grind the soaked rice. Put the rice paste into a cloths bag and drain excessive water.
  4. Use a machine to form the rice cake into a long column. Break the long column into several short segments.
  5. Put the short columns into a steammer and steam them for about 30 minutes.
  6. Use a mixer to blend the half-cooked rice columns.
  7. Use a noodle making machine to squeeze out noodles (similar to pasta-making).
  8. Boil the rice noodle in water or steam it.
  9. Dry it.
These noodles are pre-cooked. You may visit this Chinese web page for the pictures. Some cheaper rice noddles may contain corn meal. -- Toytoy 08:19, 8 November 2005 (UTC)
Here's a Chinese manufacturer of modern automatic rice noodle making machines. The noodle-making procedures are about the same but they are now made by much fewer people. -- Toytoy 08:31, 8 November 2005 (UTC)

[edit] Which C++ STL container safest to use references with?

So I learned the hard way that std::vector containers may internally resize and "reorganize" during execution of your program, meaning that if you have a container of objects, you aren't guaranteed that, &mycontainer[53] will always equal the same reference address.

I've pretty much figured out a solid configuration to set up geometric mesh structures but certain things I didn't know about the STL (not really having used it often) is making the actual implementation a bit of a pain to make it fast and relatively free of fatal bugs. For meshes with efficient operations, I need to use a more memory-reliable(?) container, where &mycontainer[53] will always equal the same memory address regardless of whether that container has 60 items, or 600,000 items.

STL documentation doesn't really explain the nitty-gritty internals of how these containers function behind-the-curtains so I'm a bit hesitant to just change my program by a kneejerk reaction and jump on any other of the STL containers. What's the most "safe" C++ STL container to use, if any, that still allows for constant-time O(1) lookups (even O(log n) isn't acceptable for meshes with hundreds of thousands of vertices and polygons meant to be rendered many dozen times per second) and, most importantly, guarantees every object in it will always have the same memory address that it did when you first inserted it any time ago?

Also, on a somewhat related note, if there are any math-dummy-friendly books by reputable authors about implementing graphics structures in C or C++ that anyone could recommend I'd appreciate it greatly. I understand meshes but I also intend on allowing animation and deformation when I get this current mess sorted out, but vertex-deformation weighted and hierarchal IK animation seems a bit scary to me -- plus, practicing this with trial and error, I could just as well be currently doing some other faux pas I'm not conscious of. --I am not good at running 22:00, 4 November 2005 (UTC)

If you want mycontainer[53] on a std::vector<T> to always have the same address, you just need to avoid resizing. The container only resizes when it grows, meaning that if you reserve the memory (using .reserve(n)), you do not need to worry.
If you cannot reserve the memory (because you do not know a priori the size and using a big reserve would be wasteful), you perhaps could use a handle idiom: instead of putting the data directly in the vector, put the data elsewhere and put a pointer to the data in the vector (for instance, use a std::list<T> for the data and std::vector<std::list<T>::iterator> as the array). It's pretty hard to avoid moving when growing, and any array-like container which avoided changing addresses when growing would probably be implemented that way.
As to graphics structures implemented on C++, you could use some libraries which already do the job, for instance CGAL. You might also be interested in the Boost Graph Library.
If you have any other doubts, just ask.
--cesarb 02:49, 5 November 2005 (UTC)

[edit] November 5

[edit] Blood flow in the human body

Are there any parts of the human body in which blood does not occur but remains healthy? -Eileen

The cornea? (Because blood vessels there would block your vision.) AySz88^-^ 05:55, 5 November 2005 (UTC)
Hair and nails? Although I'm not sure if the term 'healthy' can be said to apply here (if you ignore commercial bullshit). And the Epidermis. I believe this is what is meant by 'dead skin', which doesn't sound too healthy, but the article says it's nourished, so that's probably a wrong term. DirkvdM 10:56, 5 November 2005 (UTC)
Carilidge? Eyebrows and lashes? Artoftransformation 17:29, 9 November 2005 (UTC)
President Bush's Skull

[edit] The Maumee River, State of Ohio

It is a fact that sediment/silt suspended in the water of the Maumee River accounts for it's muddy appearance. Why is this continous,without variation in dry as well as rainy periods.

Thanks,  edg

I grew up a hundred yards from one of the two rivers that form the Maumee River, and thought all rivers were muddy brown all the time. Most midwestern rivers of that size flow through rich soil and the suspended matter is not much affected by the weather or season. Even when the river is swollen and flooding during a spring thaw the water looks the same. alteripse 00:22, 7 November 2005 (UTC)

[edit] Name of the bird, bird flu?

Hey, I found this on a blog and the author resides in Malaysia. The author is worried that the bird might have died due to bird flu (personally I doubt it). Could somebody identify the species of the bird in the pictures below, please?

Once it's named, it should be easier to search for the bird on WP or the net. Thanks __earth 02:31, 5 November 2005 (UTC)

Image:DC051104003.1.jpgImage:DC051104002.1.jpgImage:DC051104001.1.jpg

{{Name your images}}. And I've shrunk them a bit to save some bandwidth. Some kind of swallow maybe? Alphax τεχ 06:33, 5 November 2005 (UTC)

Looked like a pigeon to me..a quick troll around the net confirms it to be a Malayan Spotted Dove. (almost a pigeon)--Eye 23:59, 5 November 2005 (UTC)

[edit] Mutation of bird flu

On the news we hear it all the time: "Bird flu is pretty safe now, but if it mutates to a form that could be transmitted between humans, then it could become a pandemic"

Are the odds of bird flu mutating into such a form higher than the odds of similar mutations? We never hear "If the HIV virus mutates to being transmittable by sneezing then...", "If the cold virus mutates into being worse than pneumonia and remain as catching then...", "If the ebola virus mutates to being transmittable by mosquito then...", etc etc.

Is there a specific reason why we should be more worried about bird flu mutating in such a manner?

-— Asbestos | Talk (RFC) 05:16, 5 November 2005 (UTC)

Yes - the Spanish flu went on a similar path, and reassortment can easily mix the genes of a human and a bird flu inside a person or animal infected with both at the same time. Our article about reassortment is a sub-stub though. I'll dig up the news article I read. AySz88^-^ 05:25, 5 November 2005 (UTC)
Here is the article: link. And a link to a page describing reassortment (and sells diagrams of it): link (big pictures). AySz88^-^ 05:33, 5 November 2005 (UTC)
Interesting. Thanks. — Asbestos | Talk (RFC) 15:41, 5 November 2005 (UTC)

[edit] Synchronising Thunderbird message filters

So, I've got multiple accounts set up in Thunderbird - including a "local folders" account - and I want to synchronise the message filters on all of them. Any clues on how to do it (including shell scripts, provided they don't use perl)? Alphax τεχ 06:27, 5 November 2005 (UTC)

[edit] Muscle groups involved in jumping

Which muscles or muscle groups are performing work in the human leg during jumping? I guess I'm thinking about a jump straight up from a standing start. I would have imagined that the quadraceps were most involved, but a nerve injury to my calves seems to have curtailed my ability quite a bit. Thanks! --Creidieki 07:01, 5 November 2005 (UTC)

If you are starting from a standing position, I'd guess the quadriceps have little role, since their main action is to extend the knee, which is already extended when one is standing. The calf muscles, whose main action is to extend the ankle, would seem to have the major role I believe. Of course, the more you squat (bend/flex your knees), the more role your quadriceps can assume, which is why one can jump higher when starting from a squatting position. — Knowledge Seeker দ 08:14, 5 November 2005 (UTC)

[edit] Epilepsy fits and Sex

I wish to know whether there is a link between sex(especially in women),including all types of sex(oral,natural,etc.) and epilepsy fits, i have heard that by doing sex epilepsy fits are redueced. Is there any cure for epilepsy fits.

sandeep

  • As far as I know there's no definite cure for epilepsy. Mostly drugs are used to suppress symptoms, but occasionaly excising the part of the brain responsible for the attacks by a surgeon can help. However, such operations do carry quite a risk with them. I know nothing about the effect of sex on epilepsy, though. - Mgm|(talk) 10:23, 5 November 2005 (UTC)
  • There are some studies that suggest exercise–in general and in moderation–can be beneficial in reducing epileptiform brain activity and the overall incidence of epileptic seizures. See for example [14] for a quick review. TenOfAllTrades(talk) 13:27, 5 November 2005 (UTC)

[edit] Incorrect Java code?

I'm beginning to learn Java, and I have a good beginner's guidebook to it. It provides this very simple code:

class example {
        public static void main(String args[]) {
                System.out.println("Java drives the web.");
        }
}

I've looked over it and understood what it's supposed to do. I've stored it in example.java, and it compiles successfully to example.class (using javac.exe). However, java.exe doesn't want to run it. It tells me:

Exception in thread "main" java.lang.NoClassDefFoundError: D:\David's Stuff\David's Java stuff\example

(D:\David's Stuff\David's Java stuff is the directory I've put it in.)

I know I've made an obvious mistake somewhere, but I am only just starting Java, and would appreciate it very much if someone could tell me what I'm doing wrong. -- Daverocks 07:55, 5 November 2005 (UTC)

I don't get exactly the error you do, but if I type:
java example.class
I get
Exception in thread "main" java.lang.NoClassDefFoundError: example/class
whereas if I type
java example
I get
Java drives the web.
I suggest you drop the .class on the command line.
-gadfium 08:57, 5 November 2005 (UTC)
Yes, I tried "java example.class" in the command line, and got the same error you did. When I drop the .class (typing "java example"), it gives me the error I previously mentioned, without the "/class" at the end of the error message. -- Daverocks 11:32, 5 November 2005 (UTC)
Wait, fixed it. The command prompt had to be in the same directory as the .class file, not running it externally (I was typing: java "D:\David's Stuff\David's Java stuff\example"). I just changed directory to that, then it works. Thanks for your help anyway. I suppose learning comes out of mistakes. -- Daverocks 11:37, 5 November 2005 (UTC)
You can be in a different directory, if you add to the classpath: java -cp "D:/David's Stuff/David's Java stuff/example" example. --cesarb 13:20, 5 November 2005 (UTC)
Ah! Thank you for that great tip. -- Daverocks 11:45, 6 November 2005 (UTC)

[edit] The decay of Neutrons into Protons

Why and how does a decay of a neutron give rise to a neutrino and an electron? I see in the first place that since neutrinos and electrons aren't part of quarks at all, how does the release of them somehow change one of the down quarks into an up quark, seeing that quarks are fundamental particles and aren't composed of neutrinos or electrons. Is this something relating with E=mc², where one of the quarks get turned into pure energy, and is reformed into a new quark? And in order to comply with the laws of conservation, would it suggest some quarks have more energy than other quarks, or is this relative to their arrangement depending on what type of quarks there are in a given moment? Two down quarks and one up quark after all, seem to have more energy than one down quark and two up quarks, since the former can produce the same thing PLUS a neutrino and an electron? And since overall, it bears the material that has the abilities of both proton and electron, why is this not exercised in the atom, affecting proton/electron number, etc.? -- Natalinasmpf 12:20, 5 November 2005 (UTC)

Learn to search, I found this reletivitly quickly: [[15]]. Your question is someone confusing: A Neutron is not a fundemental indivisible particle. It would be a good idea to study and learn the ideas conveyed in Feynman diagrams. A picture is worth a thousand words.

"A free neutron will decay with a half-life of about 10.3 minutes but it is stable if combined into a nucleus. This decay is an example of beta decay with the emission of an electron and an electron antineutrino." "Momentum and energy for the two-particle decay are constrained to these values, but this is not the way nature behaves."

Artoftransformation 01:00, 6 November 2005 (UTC)

Artoftransformation, I think it's pretty silly to ask someone to learn Feynman diagrams just because they ask a question. And I would be very careful about reprimanding others for asking confusing questions, doubly so if you might not fully understand the answer yourself. -- SCZenz 07:25, 6 November 2005 (UTC)
Exactly, I changed "you should" to "It would be a good idea to" Thanks. Artoftransformation 04:53, 9 November 2005 (UTC)
Yeah, a down quark can decay into an up quark, an electron, and an antineutrino. This does not mean it is made of these things. Elementary particles interact, and sometimes this interaction takes the form of some disappearing and others appearing, without any being made of any other. Energy is conserved, as you said, according to E=mc2. The additional energy for this decay comes from the additional mass energy a neutron has over a proton, which comes from the strong force that holds the neutron together. Interestingly, protons can also decay into neutrons (then an up quark becomes a down quark, a positron, and a neutrino), but only inside atomic nuclei; here the extra energy comes from energy of the nucleus as a whole. I discussed this process, called beta decay, at some length here: Talk:Electron#Electrons_and_Down_Quarks. -- SCZenz 07:25, 6 November 2005 (UTC)
Oh, and regarding conserved quantum numbers. Baryon number is conserved, since both protons and neutrons have baryon number +1. Electron number is also conserved, since electrons have electron number +1 and the associated antineutrino has electron number -1 (or vice versa for positrons and neutrinos). Oh, and please feel free to ask if you have more questions, or if I missed something! -- SCZenz 07:31, 6 November 2005 (UTC)

As for the question of two up and one down having more energy than one up and two down : You can't divide the energy up among the quarks only like this. There are a lot of gluons involved. The energy for the beta decay of one quark comes from the whole system of the three quarks plus all the gluons, not from the quark that decays. Theresa Knott (a tenth stroke) 08:20, 6 November 2005 (UTC)

Just to avoid confusion, when Theresa talks about gluons, and I talk about the strong nuclear force, we're actually talking about the same thing. Gluons are the force-carrier particles for the strong force. -- SCZenz 08:46, 6 November 2005 (UTC)

[edit] tears

Why does tears well up in the eyes when you are feeling sad , excited, etc.???

The tears article says that "it has been suggested from their stress hormone content that tears may be a method of expelling excess hormones from the body." - Akamad 14:09, 5 November 2005 (UTC)
This has to be a candidate for the dumbest statement in wikipedia. Hormones are communication signals from one cell to another. They are typically degraded as the signal is received. They are not excreted in body fluids as a way to get rid of them. alteripse 00:14, 7 November 2005 (UTC)

Maybe they also release a pheromone which has the evolutionary purpose of inducing empathy. You know, because a tight-knit community bodes well for the success of a species. Just a thought. -- Natalinasmpf 02:44, 6 November 2005 (UTC)

Since both answers apply to at least some other animals, do those animals also cry emotionally? Some dogs often have dried-up-tear-deposits (what do you call that?). Is this natural or a result of bad breeding? DirkvdM 16:36, 6 November 2005 (UTC)
Don't forget that the primary function of tears is to lubricate the eyeball & eyelid... Alphax τεχ 03:33, 7 November 2005 (UTC)

[edit] Light

Why do light rays/beams travel in straight lines???

They don't always travel in straight lines. Gravity, for example, bends light. See General Relativity. - Akamad 14:02, 5 November 2005 (UTC)
[| Gravitational Lensing] Actaully According to General Relativity, the light travels in a straight line, but the refrence frames around large masses curves. The light still travels straight. So, In Newtonian Physics, Angle of incidence=Angle of Reflection, In Einstinan Physics, Newtonian Physics holds for frames of refrences not near large masses. -> And now onto Ricard Feynman's work: ( Rattle all cages now! )
Quantium Electrodynamics says that the light of a path is only the sum of all the paths. Again, Angle of incidence=Angle of Reflection, and the local frame of refrence is all consistant, except for the edegs of the mirror...There you may only see some of the paths...Thought experment...what would happen if you gathered edges of mirrors together? Like a difraction grating? or... the bottom of a Compact Disk. Turn over a Compact Disk. Look at the Rainbow. Newtonian physics breaks down. You do not see a mirrored surface. Einstienian Phyics breaks down. You do not see the frame of refrence changing? What you see is a large amount of partial paths, Hence the rainbow, consistant with the Quantium Elecrodynamics Theory. ( And they gave Feynman a Nobel Prize! ) Artoftransformation 22:43, 5 November 2005 (UTC)
Look at it from light's point of view. It travels 299,792,458 meters in a second. If it drifts left or right over a few seconds, we wouldn't notice. We only see a few thousand meters of the path at a time. In other words, it is like trying to see how straight a car's path is by only looking at 10 feet of the path it has driven. Kainaw 15:07, 5 November 2005 (UTC)
We would actually know immediatly, if light drifed. Everything we saw would be fuzzy, and the sun would darken in the sky. Artoftransformation 22:43, 5 November 2005 (UTC)
Because quantum electrodynamics means that non-straight probabilities get cancelled out. --Fangz 16:55, 5 November 2005 (UTC)
Except on the edges of a reflective surface. Artoftransformation 22:43, 5 November 2005 (UTC)

A single application of a force makes something travel in a straight line. Add another force is when you get a curve. Light is driven by one force (to roughly but technically incorrectly describe it)....only when you add another force, like a mirror, or gravity (for example the electrons in the silver molecules of the mirror apply an additional force to the light waves) that the path changes. When you throw a curveball for example, your muscles are applying at least two different directions of force. -- Natalinasmpf 19:42, 5 November 2005 (UTC)

Wow. Where do I start to fry this? Thanks for the contribution, but its almost all wrong. Newtonian physics [ Principle of Inertia ], does not apply to massless particles. The curvature of light is not due to a force( see curvature of space.) Light is not driven by a force, ( and Electrons are driven by the weak Nuclear Force ). Silver or Mercury atoms do not apply forces to photons. ( I will hunt down the exact feynman diagram later. ) When you throw a curve ball, a centripital force acts upon lineral force.
I said it was a poetic way to describe it. Light does not have force. It is massless. But when I meant "force", I did not mean Newtonian force, I merely meant an entity that would cause it to move forward. I'm more or less applying a philosophical argument than a physical one, anyway. Think of the language used by Zeno's paradox, it's technically incorrect, but that's irrelevant. -- Natalinasmpf 22:50, 5 November 2005 (UTC)
There are many answers to this question, depending on which model of the universe you use. Akamad is right about light bending in GR, although you could also say that light travels the straightest possible path in curved space. Anyway, ignoring issues with gravitation, some answers we might give are:
  • In basic optics, a simple form of the principle of least action is invoked, requiring light going between two points to take the shortest path possible. This is, of course, a straight line.
  • In classical electrodynamics, we can derive self-perpetuating electromagnetic waves from Maxwell's equations. These turn out, mathematically, to go in straight lines.
  • As Fangz mentioned, you can get in quantum mechanics that all components of light's (or any other particle's) wave function that don't go in a straight line manage to cancel each other out. This turns out to be a sort of derivation of the action principle used in basic optics above.
The real answer is that light does travel in straight lines, so all our models of the universe predict that this will occur(because otherwise they'd be wrong) and have reasons for it. But the reasons need not be the same from model to model. -- SCZenz 20:04, 5 November 2005 (UTC)
Except again, for the edges of reflective surfaces. I will use a refrence to this, since I disagree with all of the answers. [| Genius, by James Gleick ] Artoftransformation 22:43, 5 November 2005 (UTC)
Yes, we all know that light bounces and diffracts and refracts. I think it's fair to say that the question was asking why it goes in a straight line the rest of the time. Was that your only point of disagreement? -- SCZenz 06:55, 6 November 2005 (UTC)

I would ask you to repeat a thought experment. When asked by reporters how Einstien came up with Relitivity, he said 'What would I see if I rode on a beam of light?' Lets see if we can recreate what he saw. (Keep in mind that a frame of refrence is consistant. Right angles are right angles ). A beam of light in a vacuum would travel at the limit of speed. Nothing could travel faster. If it was traveling near a large mass, the local frame of refrence would curve and the light beam would continue straight through it, but to an outside observer( remote frame of refrence, the light beam would appear to bend, but it according to General Relitivity, it wouldnt. Again, its the local frame of refrence that although consistant with itself, would appear to a remote frame of refrence as bending. Artoftransformation 23:48, 5 November 2005 (UTC)

Either you see this immediatly, or you need to run through it a few times, or your never going to get it. If you see it immediatly, Great! If you need to run thourgh it a few more times, do. If you need more explanation, just ask. If your never going to get it. Check back in 6 months. Artoftransformation 23:48, 5 November 2005 (UTC)
A facet of genius. True genius is the ability to explain complex things in extrodinary simplicity, not detracting from the underlying ideas. This was one of Einstien's greatest strengths, that also was posessed by Richard Feynman. I hope, by answering questions here, to develop my capactiy for this facet of genius. Another important facet of genius, is that if you do not know the answer, but know where to get it, and can get it in time to make a diffrence, that is just as good. Artoftransformation 23:48, 5 November 2005 (UTC)

Just a thought with no basis whatsoever (and an attempt at that 'extraordinary simplicity'). Isn't a straight line defined by how light travels? DirkvdM 16:48, 6 November 2005 (UTC)

They are related. A straight line is defined as the shortest distance between two poins, in Euclidian Geometry. I would say that this is a minimal path definition. As a colloary, light would follow this path, assuming that it was traveling through Euclidian space, and not relativistic space. --Artoftransformation 06:13, 12 November 2005 (UTC)

[edit] Functions

Why is it that only one to one relations and many to one relations are considered functions???

From what I gather, a function, by definition must always be many to one. So basically, the answer to your question is: it's defined that way. (Perhaps someone smarter than me can give a reason as to why it's defined as such) - Akamad 14:16, 5 November 2005 (UTC)
See Function (mathematics). --JWSchmidt 14:22, 5 November 2005 (UTC)
To be overly simple: A function is a function if and only if you get the same answer (Y) every time you give it the same input (X). You could have a one-to-one relation (y=x+4) or a many-to-one relation (y=4 -- no matter what X is, you get 4). You can even have one that gives multiple Y's for a single X (y=sqrt(x) -- sqrt 9 is 3 and -3) as long as it always gives the same set of Y's. What you cannot have is a function that produces random output. Then, it would not be a function. Kainaw 15:01, 5 November 2005 (UTC)
Actually, as the function article says, "In mathematics, a function is a relation, such that each element of a set (the domain) is associated with a unique element of another (possibly the same) set (the codomain, not to be confused with the range)", a function must give one single "a unique" Y value for each X. To make the y=sqrt(x) example a funtion, you would only give the principal root, not the negative one. --Borbrav 17:54, 5 November 2005 (UTC)
Right. This sqrt thing is pretty common: sqrt(9) is not 3 and -3; rather if x2 = 9, then x is sqrt(9) or -sqrt(9). — Sverdrup 23:33, 5 November 2005 (UTC)
However, note that it only takes a little notational handwaving to identify sqrt(x) with the preimage of x under x = y2, giving us a sense in which sqrt(9) = {3, -3}. But you're right in general: a function is a single-valued total relation — the fact that this single value might be a set does not change this basic definition. —Ilmari Karonen (talk) 14:35, 6 November 2005 (UTC)

[edit] Thought experiment

Suppose I have a ball of some mysterious substance that is unaffected by any force - especially gravity and electromagnetic forces. If I let go of this ball (of course, it would be hard to hold in the first place), what would happen to it? Would it move relative to me? Where would it go?--Fangz 17:02, 5 November 2005 (UTC)

By Newton's second law, an object not acted on by any force continues in a straight line at whatever speed it was last going at (i.e. wherever, and however, you were holding it). Thus as the earth turned under it, it would appear to fly up into the sky, move east, and go out of the atmosphere. It would then fly out of the solar system.
It's worth noting that any object being unaffected by gravitation is completely inconsistent with the structure of space and time in General Relativity. -- SCZenz 17:08, 5 November 2005 (UTC)
I disagree. Massless particles do behave that way with respect to gravity and chargeless particles behave that way with respect to electromagnetism.. StuRat 23:15, 5 November 2005 (UTC)
You're right about electromagnetism, and dead wrong about gravity. Massless particles curve the same as massive particles under gravitation. That's why light can't escape from a black hole. This has to do with the structure of space and time in General Relativity, as I said above—specifically, gravitation is caused by the curavuture of spacetime, rather than by a force, so everything is affected by it. -- SCZenz 02:00, 6 November 2005 (UTC)
Then you can agree that photons can go into orbit?
Yes, indeed they can. Not around the earth or the sun, which would have to be much smaller while keeping the same mass in order to have a photon orbiting them. But a black hole could certainly have a photon in orbit. -- SCZenz 06:41, 6 November 2005 (UTC)
Another explaination for light not escaping from a black hole, is that black holes have no hair. Only mass, rotation and position. No temprature, No Color. Artoftransformation 03:59, 6 November 2005 (UTC)
The no hair theorem is a statement about black holes, not an "explanation" for light not escaping. Interestingly, the existance of Hawking radiation implies that black holes do have a temperature, which gets smaller the more massive they are. Oh, and by the way, black holes can have electric charge as well. -- SCZenz 06:41, 6 November 2005 (UTC)
I see that the thought experment is missing something. What physical laws are going to be obeyed in this experment, and which ones are to be ignored? Does the ball (shape of minimal surface) hold itself together by gravity? You lose gravity, it flies apart. Does the ball posess any relitive motion in regards to your hand? The Earth? The Sun? The Milky way? The Observible Universe? Artoftransformation 03:59, 6 November 2005 (UTC)
I assumed it was stationary with regard to your hand, and went in a straight line (assuming flat Newtonian space) from there. -- SCZenz 06:41, 6 November 2005 (UTC)
  • It's obvious the direction it moves will depend on the time of day and day of the year (taking into account Earth's rotation and orbit of the Sun, respectively). Would galactic rotation have any visible effect, I wonder? --Bob Mellish 18:53, 5 November 2005 (UTC)
    • Yes, eventually. In the short term the object would be moving basically right along with the sun's orbit around the galactic center (except for the effect of earth's rotation), which I believe takes many millions of years to complete a revolution. But obviously it would separate after a while. -- SCZenz 19:20, 5 November 2005 (UTC)
      • The object will initiall move up, slowly at first, but its trajectory would seem (to an earthbound observer) to slightly bend to the west, not east. Time of day and season do not affect this at all, but the speed will be a function of the latitude on earth where it was released. Owen× ☎ 22:53, 5 November 2005 (UTC)
        • OK then, let's release it at the north pole. --hydnjo talk 22:59, 5 November 2005 (UTC)
          • As soon as you release it, it will disintegrate, with subatomic particles moving in different directions and velocities, with a velocity distribution related to the temperature of the object. — Knowledge Seeker দ 04:25, 6 November 2005 (UTC)
            • I think that's defeating the point of the thought experiment, isn't it? -- SCZenz 06:41, 6 November 2005 (UTC)
              • All right, yes; I just couldn't resist. Although I think precision is necessary in thought experiments; often paradoxes or strange conclusions turn out to be the result of ambiguous or improper assumptions. That being said, I think the key here is what you (SCZenz) mentioned earlier: we really don't know what will happen. An object unaffected by gravitation is inconsistent with our current formulation of physics. All objects (particles, waves, etc.) are affected by gravitation; if not, black holes could not exist. Actually, my favorite author, Isaac Asimov, tackled a similar problem in his excellent story "The Billiard Ball". I don't wish to spoil the story since I encourage you all to read it and read his other works as well, so I will place the gist of it on a separate page (also I don't plan to leave it up forever so just look through the history if you find the summary missing). — Knowledge Seeker দ 06:50, 11 November 2005 (UTC)

The way I see it: of course, it would be hard to hold in the first place. No, you just WOULDN'T be able to hold it at all, because you'd NEED to use a force on the object for this. Since sub-atomical electrical forces is what makes you hit a wall, and not go through it, such substance would just go through everything. But it doesn't stop there, because if the mysterious substance is completely immune to any forces, a particle of such substance wouldn't have any force on other particles of the same substance, so it'd just become a floating mass of random moving particles that permeate everything on their way. ☢ Ҡieff⌇↯ 23:30, 6 November 2005 (UTC)

You're right of course but assume that the "ball" assumes those magical properties at the instant that it is released. The essence of the question is I think, would there be any bias or disposition to scatter in a preferred direction say, tangent to the earth's orbit around the sun or whatever. --hydnjo talk 00:01, 7 November 2005 (UTC)
Yes it would, but alas, we can't know where it'd go. All the movements we know there exist (Earth around itself, around the Sun, the Solar System, Galaxy around itself, Galaxy among other galaxies etc) are just noticeable because we have a reference. To know where this object would go we'd have to find out the resultant "absolute speed" of it, and since we cannot physically measure this we can't really give a good answer. ☢ Ҡieff⌇↯ 02:01, 7 November 2005 (UTC)
That's not true. There's no such thing as absolute speed. It would travel in a straight line along its trajectory at the moment that it became non-interacting, and we know exactly what that trajectory is, because we're on it. Of course, you need to give that trajectory with respect to something, but that's always true. -- SCZenz 02:25, 7 November 2005 (UTC)
That's why the term was within quotes. Now, the issue I pointed out is that our trajectory is not straight, because we're under the influence of several centripetal forces. Our trajectory is actually the result of all these circular motions summed up. That's why our current trajectory is not enough to tell the path the object will follow. ☢ Ҡieff⌇↯ 04:01, 7 November 2005 (UTC)
But we have an instantaneous velocity now; it will follow that. It is changing quickly because of the earth's rotation, more slowly because of the earth's orbit, even more slowly because of the sun's orbit around the galaxy, and more slowly still because of the acceleration of the galaxy itself. That gives us a pretty good idea what our current velocity is; any other affects are very small. -- SCZenz 05:38, 7 November 2005 (UTC)

[edit] chemistry

please balance this equation with states and synbols.

aluminium = copper(II) - copper = aluminium sulphate.

Please read the top of this page, and do your own homework. Reading our Chemical equation article will help. -- SCZenz 17:21, 5 November 2005 (UTC)
The Chemical Symbol for Aluminum is Al
The Chemical Symbol for copper is Cu
The Chemical Symbol for Sulphur is S
See [[16]]
Substituting these you get Al n =Cu(II) n - Cu n = AL n S n.

Now. What is the valience values to substutue for n to make the Equation balence?

Artoftransformation 22:55, 5 November 2005 (UTC)
  • That equation can't be balanced. You can't make sulphate out of nowhere and an equation needs at least 1 plus sign and an arrow between reactants and products. The valence of the elements are in the articles on aluminum, copper and sulphur. I'm pretty sure your chemistry study book explains balancing equations in detail. - Mgm|(talk) 20:48, 6 November 2005 (UTC)

[edit] Two Significant Breakthroughs in Science

A Radio program featuring a promonant physasyst spoke of two significant scientific breakthroughs this year. A picture of a electron at 1 fermi-second, and the detection of a particle at two simultanious locations. Questions: What is a world wide web link to a picture of an Electron, and who were the authors of the paper on the simultanious particle locations? Artoftransformation 22:55, 5 November 2005 (UTC)

[edit] most powerful hallucinogen

What`s the most powerful hallucinogen in the world?

Probably LSD. A single dose is tiny (micrograms). ‣ᓛᖁ♀ᑐ 00:37, 6 November 2005 (UTC)
Lysergic Acid Diethylamide or LSD is one of the most powerful hallucinogens that radically changes a person’s mental state by distorting the perception of reality.
Keep in mind, that almost all hallucinogens are clasified as schedule 1 narcotics, and are subject to criminal penalties: "5-40 years to 10 years to life. Maximum fine: $2,000,000.00 to $4,000,000.00. If death or serious injury occurs 20 years to life." Artoftransformation 00:42, 6 November 2005 (UTC)

"Salvinorin A, a neoclerodane diterpene, is the most potent naturally occurring hallucinogen known and rivals the synthetic hallucinogen lysergic acid diethylamide in potency." (source) --JWSchmidt 03:11, 6 November 2005 (UTC)

The most powerful hallucinogen known is probably life it's self. :-)--Eye 22:35, 6 November 2005 (UTC)

Along the same lines, love has been known to make people act pretty crazy too. Garrett Albright 03:11, 7 November 2005 (UTC)

[edit] Why was synthetic rubber made?

My question is why was synthetic rubber made. Was it because they needed a more suitable rubber for everyday life, or was there another reason for making synthetic rubber. Also what is the advantages of synthetic rubber?

Thank you

It has materials properties that natural rubber doesn't, plus it can be made with local materials (without imports), which can be important if, say, you are being embargoed because you are at war. - CHAIRBOY(☎) 23:57, 5 November 2005 (UTC)

Thank you for your reply. now i have a different question to ask still concerning Rubber. Which is better, Natural rubber or Synthetic and why?

Again thank you for your help

That would depend on what you call 'better' (hardly anything is ever so one-dimensional). For what purpose? And would cost-efficiency be a factor? About the first question; one may try to find an alternative to something, but most of the time it's just a matter of doing general research and then finding something that, hey, has capacities that you could use for something. Irrespective if whether there already something else that can be used for it. The trick is to keep an open mind regarding the possible uses of something. Not that any of this is an answer to any of your questions... :) To remedy that, a synthesized product is often purer, generally giving you more options to alter its characteristics by adding desired impurities. DirkvdM 17:06, 6 November 2005 (UTC)

Thank you very much for your help and information, you helped me alot!!

[edit] November 6

[edit] Sinus headaches

What causes a sinus headache? How can they be treated quickly? ‣ᓛᖁ♀ᑐ 01:12, 6 November 2005 (UTC)

The term (as used) just means "head pain in the area of the sinuses", but properly ought to mean "head pain caused by obstruction of sinus drainage". Treatment aims at "unblocking", usually through the use of decongestants, along with antihistamines to reduce mucus secretion and aspirin for analgesia. If the occlusion of drainage is caused by a sinusitis, other measures, such as antibiotics, might be used. - Nunh-huh 01:17, 6 November 2005 (UTC)
Use nasal decongestants cautiously as they can lead to the troublesome problem of Rhinitis medicamentosa. As above, treatment best focuses on clearing the sinus drainage tracts. Obviously as with any medical problem there can be many important risk factors that may need to be considered, as infections or more serious causes or complications of sinus headaches may need to be investigated.—Gaff ταλκ 00:28, 7 November 2005 (UTC)

[edit] facts about human induced global warming

I am wondering about the FACTS related to human induced glabal warming. Is there some concrete scientific data? Or it is a hypothesis?

See global warming. Superm401 | Talk 02:52, 6 November 2005 (UTC)
Last year, in fact, the White house spokesman Scott McClennan said that The Ozone problem was solved, even if we never had an ozone hole to being with. Not to worry. The 2005 Ozone season was the worst on record, covering an maximum of 28 million square miles.
[Common dreams]"With White House Approval, E.P.A. Pollution Report Omits Global Warming Section" by Andrew C. Revkin
This is a classic wife-beater question. Artoftransformation 23:03, 6 November 2005 (UTC)
Is only good science mandated by policy?
"The proponents of 'business as usual' have claimed that chemical and nuclear technologies have created only minor problems or no problems whatsoever -- but time after time science has shown otherwise. They said global warming was a "chicken little" fantasy. They said the Earth's ozone shield couldn't possibly be harmed. The White House They argued that asbestos was benign. They said lead in paint and gasoline was entirely safe. They said harm from hormone-disrupting chemicals was imaginary. They said a little radioactivity might actually improve your health. They said human health was constantly and consistently improving -- until scientific study revealed increases in birth defects, asthma, diabetes, attention deficits, nervous system disorders, diseases of the reproductive system, immune system disorders, cancer in children, and on and on. In each of these cases science showed that the advocates of 'business as usual' were simply wrong.Science cannot solve all our problems or tell us everything we need to know, but it remains a powerful tool for reaching agreement about the nature of reality (at least for those parts of reality amenable to scientific inquiry)." -Tim Montague
[[17]]
I believe "health was constantly and consistently improving" is generally true. There have been exceptions, however, such as AIDS in the third world, alcoholism in Russia, and potentially obesity in the US, where life expectancy may actually decrease, instead. StuRat 18:15, 7 November 2005 (UTC)
I certainly agree that the evidence for human-induced global warming is overwhelming. However the issue is certainly not uncontroversial, and it would be wrong to imply so. Superm401 | Talk 19:15, 6 November 2005 (UTC)
Of course, whether the controversy is political, or scientific, is a controversy in itself. --Fangz 19:22, 8 November 2005 (UTC)

Surely one big volcanic explosion or asteroid collision would have far greater effect than anything human 'civilization' (other than all out nuclear war) could do?

I actually disagree. The explosion of krakatoa or the Tunguska event, although they altered the color of sunsets for months, didn't cause large scale glacial/polar melting. An asteroid collision on the magnitude of those that struck Central America or North America would probably become an Extinction Level Event(ELE). Artoftransformation 03:48, 8 November 2005 (UTC)
The IPCC models take into account the effects of volcanic eruptions. Generally, the ash emitted do tend to reduce the effect of Global Warming, causing their own global cooling, at least for a short term. But global warming is still happening on an unprecedented scale, so, assuming that volcanic frequency are generally constant over time, sitting and hoping for a lot of volcanic eruptions to save us does not seem to be a good strategy.--Fangz 19:22, 8 November 2005 (UTC)

[edit] The effect of wind upon atmosphere pressure

Hi,I would like to ask that does wind affect the atmosphere pressure at a place?Will the atmosphere pressure affected by the sea breeze?

While winds are an effect of different atmospheric pressure, they do not, on average cause changes in pressure. Obviously, gusts of wind can locally and temporarily increase the pressure. -- Ec5618 15:11, 6 November 2005 (UTC)
The drop in pressure is exactly how they measure the strength of storms.
[[18]]

[edit] Special Relativity

I've been trying to start up a personal study of the Relativity Theory and related concepts. My problem is as follows. Consider a situation with two clocks, A and B. From the viewpoint of clock A, clock B is moving at a constant speed. If I understand special relativity correctly, time moves faster for clock B, because it is moving. When clock B returns from it's journey, clock A wil be a little bit behind clock B. So far so good, but if we choose clock B as a reference frame, instead, it's clock A that's moving, so clock A should be moving faster, and clock B should be behind when they are re-united.

I feel I have some fundamental misunderstanding of the theory, and I was hoping someone might clear this up for me (or at least point me to some page that explains this).

While I'm at it, I was also wondering if somebody could recommend a good book explaining both special and general relativity, at a thorough level. I'm quite willing to make an effort and study the complex geometry involved in general relativity, but right now, I don't really know where to start.

Many thanks, risk 13:40, 6 November 2005 (UTC)

  • Have a read at the Twin paradox article which addresses your first question. --hydnjo talk 13:53, 6 November 2005 (UTC)
  • A good introduction to SR is Taylor & Wheeler's Spacetime Physics. It's pretty readable and clear even for a non-specialist. --Bob Mellish 17:15, 6 November 2005 (UTC)

Thank you both very much. This, and the books listed on General relativity resources (can't believe I missed that one) should be enough to get enough of a foothold on this subject. risk 01:52, 7 November 2005 (UTC)

You got it the wrong way around. Time moves slower for the moving object. DirkvdM 07:55, 7 November 2005 (UTC)


The way I like to think of it, I believe it's one way it was explained in Greene's The Elegant Universe, is that time is something you accumulate, and motion causes your accumulation rate to drop (you 'spend' time accumulation to go fast). So, an object with more relative motion than another is experiencing less time than the non-moving observer. This isn't an effective metaphor considering that time is relative and its not truly possible to quantify the 'spend' rate, but its a neat way to visualize it if you don't have a background in physics. And for your second question, Brian Greene's The Elegant Universe and Fabric of the Cosmos are two good books for someone interested in getting a good lesson in modern physics, with enough background for it to (mostly) make sense.

[edit] Lotto probability

Assume we have a lottery where K numbers are selected from N possible values. Probability states that the number of possible rows are \frac{N!}{K!(N-K)!}

Assuming we have a drawing D, how do I calculate how many of the possible rows has X matches in D (1≤X≤K)? I've tried to deduce a formula from statistics found elsewhere, but I can't seem to get it right.

I need this expressed as a formula to convert to code for a program I'm making to determine probabilities, which will in turn be used to derive reasonable values for K and N, as well as a fair distribution of winnings. --Pidgeot (t) (c) (e) 16:58, 6 November 2005 (UTC)

First, do you mean by "rows". Give an example, please. Superm401 | Talk 19:18, 6 November 2005 (UTC)
A row would be a selection of K values from 1 to N. For example, let's say N=20 and K=3. A valid row could be 3, 5, 16.
The proper term would be combination, now that I think about it. It had slipped my mind as I wrote the question, though.
To clarify the problem with an example:
Assume we have a lottery where 6 (K) numbers of 30 (N) are selected. In such a lottery, there are 593,775 possible ways to select the numbers (any given number cannot be drawn twice, and the order is not important).
Given a specific selection, I need to find out how many of the possible selections have all numbers match with the given selection (that part's easy - 1), but I also need to find out how many have 5 matches, 4 matches, 3 matches... all the way down to 1.
This could be calculated through brute-forcing, however, N and K have not been determined yet, so this would be impractical - I need a formula that can be used to calculate this regardless of the value of N and K.
I hope my problem is more understandable now. :) --Pidgeot (t) (c) (e) 19:48, 6 November 2005 (UTC)

Well, you have K drawn numbers and N-K non-drawn, then there are

{K \choose X} {{N-K} \choose {K-X}} = \frac{K!(N-K)!}{X!(K-X)!^2(N-2K+X)!}

rows containing exactly X drawn numbers. Quite simple, to choose such a row, you must first choose X drawn numbers out of K, and then K-X non-drawn numbers out of the remaining N-K. Divide by the total number of possible rows (above) to get the probability of a row having exactly X drawn numbers. —Ilmari Karonen (talk) 20:04, 6 November 2005 (UTC)

Note that this assumes that the number of drawn numbers (K) equals the length of a row (K'). If not, the formula becomes
{K \choose X} {{N-K} \choose {K'-X}} = \frac{K!}{X!(K-X)!}\frac{(N-K)!}{(K'-X)!(N-K-K'+X)!}
which obviously reduces to the earlier formula if K = K'. —Ilmari Karonen (talk) 20:14, 6 November 2005 (UTC)
This would seem to be JUST what I need. Thank you very much! ^_^ --Pidgeot (t) (c) (e) 20:22, 6 November 2005 (UTC)

[edit] Relativistic harmonic oscillator

Is there such a thing as a relativistic harmonic oscillator? --HappyCamper 21:31, 6 November 2005 (UTC)

Well, instead of writing F = -kx and F = ma, you could write,
F = \frac{dp}{dt} = \frac{d}{dt}(\gamma mv) = m\frac{dx}{dt}\frac{d\gamma}{dt}+\gamma m\frac{d^2x}{dt^2}
You'd keep F = -kx, and you'd need
\frac{d\gamma}{dt} = \frac{d}{dt}\frac{1}{\sqrt{1-v^2/c^2}} = \frac{2}{c^2}\frac{dx}{dt}\frac{d^2x}{dt^2}(1-\frac{1}{c^2}(\frac{dx}{dt})^2)^{-3/2}
This would give you an ugly differential equation, which you might be able to solve somehow, maybe. I've never seen this in a texbook, either because it's too hard, or because it doesn't illustrate anything much, or both. -- SCZenz 21:51, 6 November 2005 (UTC)
Oooh...take a look at this paper here: [19], isn't this neat? This is quite interesting actually. No wonder why I haven't seen this in the textbooks. --HappyCamper 22:12, 6 November 2005 (UTC)
Looks like that's quantum mechanical and relativistic. Eek! ;) -- SCZenz 23:09, 6 November 2005 (UTC)
Actually this science was developed to understand Pulsars, which are relitivistic harmonic oscillators. Artoftransformation 23:22, 6 November 2005 (UTC)
I know :-) - It's such a beautiful theory. Wouldn't have come across it if it weren't for Wikipedia! --HappyCamper 00:40, 7 November 2005 (UTC)

[edit] November 7

[edit] PaK 35 vs PaK 36

Are there significant differences in the two AT guns? Lots of references have PaK 35/36, which makes me think that there are not many differences between them, but then again, why would they give them different numbers if they're almost identical? (Not sure whether this belongs to humanities or science, feel free to move.) WP has an article for PaK 36, but not PaK 35.
-- Миборовский U|T|C|E 00:23, 7 November 2005 (UTC)

[edit] Wikipedia in Firefox's search bar

I found that there existed a firefox plugin at http://mycroft.mozdev.org/download.html to add an en.wikipedia search to the standard searches on Firefox. However, typing a query in the box leads only to the Wikipedia search page. Is there anyway to fix it so that it acts exactly like the search box on the left panel in Wikipedia? i.e. so that a valid article name search, e.g. "Wikipedia" will go straight to the article, and an invalid one goes to the search page? --Mary 01:49, 7 November 2005 (UTC)

Not really, but you can make a bookmark with the URL http://en.wikipedia.org/wiki/%s and set the keyword "wp" on it - then all you have to do is type "wp Main Page" into the location bar and you will end up at the Main Page. Alphax τεχ 03:42, 7 November 2005 (UTC)
The firefox plug-in did seem to work before the update to MediaWiki 1.5, and it hasn't since. You might want to let the person who wrote the plug-in know that their plug in doesn't work anymore- they might update it.--nixie 03:45, 7 November 2005 (UTC)
Wikipedia (EN) - Instant is the one you are looking for. See this link. ☺
--Chaosfeary 03:55, 7 November 2005 (UTC)

Actually, that one works exactly the same as the other one: a valid article name, such as "Test", goes to the search page for that result. Any others? --Mary 23:12, 7 November 2005 (UTC)

Sorry, I meant Wikipedia (EN) - Instant, at the same link.
--Chaosfeary 23:27, 7 November 2005 (UTC)

[edit] Elevation

While I was on a recent trip through California, I noticed that at the border of towns, there were signs noting the elevation. How is this measured, especially in towns that are both high in elevation and far from the ocean? I checked above mean sea level, but there wasn't a lot there about measurement. Meelar (talk) 02:04, 7 November 2005 (UTC)

  • For high-accuracy measurement of fixed locations, this kind of thing was measured by surveying techniques; in the old days with theodolites and triangulation from markers, these days you can just use a GPS receiver, preferably a high-accuracy surveyor's instrument for best accuracy. --Robert Merkel 04:04, 7 November 2005 (UTC)
  • These markers, benchmarks, are scattered throughout the country. Each has its elevation known, so my guess is that the elevation for the sign is just taken from the nearest benchmark.
  • I don't think a surveyor's GPS unit is much more accurate than anyone elses - it's using the same satellite signal (is +/- 5 m what you can get these days?). However, if you are using two GPS units with one of them sitting on a benchmark - the accuracy can be much better (within millimeters).
  • I don't know how you get the elevation of the benchmark. The elevation of the benchmark is usually related back to the Mean Sea Level (which, in Australia at least, is averaged from around the country). If you know the height of one benchmark, you can traverse to another (measuring everything as you go) to discover the new benchmark's elevation. But how do you make sure that a benchmark in Perth has the correct elevation (with respect to Mean Sea Level) as a benchmark in Melbourne? Can you use the local sea level?--Commander Keane 20:38, 7 November 2005 (UTC)
Neither the surveying nor the theodolite article is very clear on this, but I suppose in the olden days they used double triangulation. Starting from the first benchmark, at the coast, first you measure the distance as described in triangulation and then you take the 'height angle'. This, plus the distance gives you the info to determine the height of a point. Now you have a new benchmark and then you contininue from there. Is this correct? DirkvdM 10:09, 8 November 2005 (UTC)
Yes that's right DirkvdM, that's how you find the elevation of one benchmark from another. It's not really an olden-days thing either - if you have seen a surveyor near a construction site (probably down the road from the site, a couple of hundred metres) then they are implementing this process. The thing is, can you get the Mean Sea Level from your local sea level? If you can then you just start at the coast as you said.--Commander Keane 10:40, 8 November 2005 (UTC)
I've added it to the Surveying article, under 'Method' because that explanation was missing there. See if I got it right again this time, because I reworded it a bit. Or is this also explained elsewhere?
By the way, shouldn't an answer here always lead to an addition to an article? Because if something needs to be answered here, it is obviously missing from the encyclopedia. DirkvdM 15:45, 8 November 2005 (UTC)
Yeah, I guess the answers to many questions on the RD need to be put into the encyclopedia. This is something I noticed that was missing from the Surveying article a couple of months ago, but I'm not an expert so I didn't add it in. But what we know is better than nothing, I'll head over to the article now. I'm still wondering about the whole sea level thing. --Commander Keane 16:10, 8 November 2005 (UTC)

[edit] Hemopoietic stem cells

Hello,

I would like to know if the CFU cells are the only blood forming cells in hemopoietic stem cell formation. basically what I need to know is the different types of blood cells developed from hemopoietic stem cells and how they are formed? I have been searching your website and other search engines and cannot seem to find this answer in full detail.

Thank you

Patrice Colbert

  • Try searching the web also under Hematopoiesis (rather than hemopoeisis). This was the term under which we studied it at my medical school. Wiki sources are below:
Haematopoiesis
Pluripotential hemopoietic stem cell
Tulane University
Blood
Good luck.—Gaff ταλκ 03:13, 7 November 2005 (UTC)
  • As a reminder, however, neither Wikipedia nor the Reference Desk are search engines. Wikipedia is an encyclopedia. People would do well to remember that. Superm401 | Talk 03:26, 7 November 2005 (UTC)

[edit] SATA versus ATA

Which is better, in terms of personal computer hard disks?

  • 8 MB - ATA-133

or

? The ATA one for some reason costs £9 more and quotes "this ATA version of the disk is dedicated to professional users" - Slower, but more reliable, or something like that?

I'm very confused, if any techy people out there could help out it would be awesome.

Thanks --Chaosfeary 03:44, 7 November 2005 (UTC)

With questions like these, I'm tempted to reply "If you don't already know the answer, it doesn't matter". IIRC both ATA and SATA are faster than the drives can actually transfer information themselves. The other question is what your motherboard supports, if your computer is a few years old it may not support an SATA drive. However, if it does, and all other things being equal (the disk rotation rate, seek time, and probably more importantly the warranty support) I'd save the 9 pounds and spend it on some fine English Real Ale (ignore this last part if you're under 18 though...)--Robert Merkel 06:31, 7 November 2005 (UTC)
That last bit depends on the country you're in of course (assuming you were referring to the law). But about SATA disks. I have two and have some problems installing msWindows on them. Linux works fine, but WinXP crashed after a few months and then when I tried Win98 it acted up from the very beginning, regularly freezing. The most striking thing is that I sometimes need to move the mouse to get it to continue. I should add that the drives are connected to a hardware raid that I don't use (as a raid that is). And don't know if that might cause problems. But more in general, SATA is a fairly new technology. Often, this means that certain things don't work well (yet), but in the case of hard disks I thought all the logic is in the drive and the OS doesn't even know or care what type of drive it is addressing. So there shouldn't really be any problems, right? DirkvdM 08:14, 7 November 2005 (UTC)
That depend on whether you run it in emulation of native mode. Native is faster because of command queuing, but you can't install Windows on it without using a driver floppy/CD for the AHCI. --R.Koot 11:31, 7 November 2005 (UTC)
And how do I determine that? I can't remember seeing anything about native/emulation mode in the BIOS, which seems the most logical place. DirkvdM 10:08, 8 November 2005 (UTC)

[edit] Moles

I have a mole on my neck with a single hair growing out of it. Is this genetically determined, or is it due to nurture? 147.9.162.249 04:45, 7 November 2005 (UTC)

A search for "mole" would have led you to Mole (skin marking). Dismas|(talk) 07:36, 7 November 2005 (UTC)
MOLEY MOLEY MOLEY!

[edit] ford car parts

ford mondeo 2.0l hc series 1996 rear bumber

This is neither a digital junkyard nor a dealer of auto parts. If you are looking for someone who does sell this part, I suggest using google.com to find them. Dismas|(talk) 07:33, 7 November 2005 (UTC)
Please don't bite the newbies! ;) Trollderella 16:47, 7 November 2005 (UTC)
At least not without fava beans and a nice chianti. StuRat 17:54, 7 November 2005 (UTC)
Know any good Noobs recipies? --Artoftransformation 03:54, 12 November 2005 (UTC)
Isnt this the kind of car that was featured in the Movies 'Mad Max' and 'The Road Warrior?' Artoftransformation 03:01, 8 November 2005 (UTC)
Germany and Italy. Sorry, my mistake. Nightrider was driving a 'Holden HQ LS Monaro'

[edit] scientific reason

Why do we get a sneeze when we look towards the sun.

  • I don't sneeze when I look anywhere near the Sun, but please remember that looking into the soon directly is VERY bad for your eyes. Don't do it. - 131.211.210.13 10:10, 7 November 2005 (UTC)
  • I've noticed this effect myself—it sometimes happens when I suddenly go out into bright sunlight, not necessarily looking straight at the sun. I've never heard a good explanation for it, though. Maybe it's a chronic allergy to photons. --David Wahler (talk) 13:00, 7 November 2005 (UTC)
  • See our article on photic sneeze reflex. —Ilmari Karonen (talk) 13:06, 7 November 2005 (UTC)
    • Oh my Tesla! I've always wondered about that, and we DO have an article on it? Goodness, I love this place! <3 ☢ Ҡieff⌇↯ 13:29, 7 November 2005 (UTC)
I once heard someone say this about looking into a lightbulb (which gives off much much less light). And it worked for me when I felt a sneeze coming on but not quite 'getting there' (a very frustraring thing, considering how orgasmatic a sneeze can be). But then I found out the light doesn't really matter, Just looking up did the trick. Then again, this might be because the action makes me concentrate more on the sneeze. Anyway, the article says it's only present in certain people, si this trickj shouldn't quite work for everyone - except when it's the phenomenon I just described. DirkvdM 10:17, 8 November 2005 (UTC)

[edit] Jumping to change Earth's direction of motion

Every once in a while, you hear about people who want to have mass hopping sessions to influence the direction the Earth is moving. By conservation of momentum, this cannot work. But a few days a colleague of mine tried to explain why it would world in terms of forces, and (to my great chagrin) I couldn't find a fault in her reasoning. Might someone perhaps be able to show me the hole in her explanation?

If a person jumps up, the act of lifting off exerts a "downward" (in the local sense, you know what I mean!) impulse on the Earth (Newton III). The person becomes airborne, and when he lands again, the impact produces another impulse "downward". Net effect: two impulses in the "down" direction. While each is negligible, if enough people did this...

I know that there is a really blatant hole in here somewhere, I just can't find it. Highly embarassing. Might someone be able to point it out? —QuantumEleven | (talk) 10:35, 7 November 2005 (UTC)

Obviously, the force pulling that person down, the force of gravity, is providing a constant impulse upward, while the person is airborne.
Compare with two objects of equal weight, as opposed to a person on a much larger mass. If one object were to jump off of the other, the objects would move away from eachother. But eventually, the force of gravity would put both masses back to eachother, so they would arrive at the exact same spot. -- Ec5618 11:00, 7 November 2005 (UTC)
It isn't quite the same spot — Earth is rotating. This should have the greatest effect if one jumps from the equator at the same time each day; what time would maximize orbital decay? Would exactly half a rotation later be the time that maximizes the chance of colliding Earth with Mars? ‣ᓛᖁ♀ᑐ 15:28, 7 November 2005 (UTC)
Plus it also comes down to the mass of the earth, the mass of the earth is far far too large to move it by jumping, no matter how many people jumped. The mass of the earth is 5.97E24kg, tht total mass of all the people is (assuming 6 billion people at 100kg each) is 6E11kg. Akamad 11:25, 7 November 2005 (UTC)
Your friend's error is not taking into account all the forces coming into play. If it were just those two, then (by Newton's third law again) the net force on you would be upward, and you'd fly off into space. She seems to have forgotten the force of gravity, which exerts an upward force on the Earth and a downward force on the person. --David Wahler (talk) 13:04, 7 November 2005 (UTC)

The force of gravity pulls the Earth upward, toward to people in the air, by an amount equal to the downward forces. Otherwsie, if any force is exerted on the Earth in just one direction, such as when an atom in space hits the Earth at high speed, the Earth will move, just by an extremely small amount, due to the difference in mass. StuRat 14:09, 7 November 2005 (UTC)

You know there had to be a mistake somewhere, because of conservation of momentum. And yeah, it's the force of gravity, as discussed above. -- SCZenz 16:04, 7 November 2005 (UTC)

Hm, right. How quickly should Earth be rotating by the time it hits the Sun? ‣ᓛᖁ♀ᑐ 16:30, 7 November 2005 (UTC)

...I think it may take up to 1023 years for one person to cause the Earth to fall into the Sun by jumping. Better start now. (On the other hand, according to [20], all that jumping will probably cause Earth to explode instead, after only one-third of the total time needed.) ‣ᓛᖁ♀ᑐ 17:00, 7 November 2005 (UTC)

No, it won't ever fall into the Sun, for the reasons listed above. Another way to think about it is as the Earth and people on it as a closed system. Unless something enters or leaves the system, there will be no change in the Earth's orbit (except a temporary change, during a jump). StuRat 17:43, 7 November 2005 (UTC)
Are you sure of that? The direction of the force when the jumper returns to the ground is separated from the direction of the jump by about 15 arcseconds, for a jump of one second at the equator. The forces don't quite cancel out. ‣ᓛᖁ♀ᑐ 18:19, 7 November 2005 (UTC)
I was going to disagree based on conservation of momentum, but on second thought, the Earth isn't really a closed system — it's continually interacting gravitationally with the Sun. If we're going to treat the effect of a jumping person on the Earth's momentum as non-negligible, we also need to account for the tidal effects caused by the momentary change in the Earth's quadrupole moment. So I'm not so sure any more... —Ilmari Karonen (talk) 18:29, 7 November 2005 (UTC)
Oops, this isn't going to work until the Moon is in geosynchronous orbit, due to tidal acceleration. How long will that take? ‣ᓛᖁ♀ᑐ 19:11, 7 November 2005 (UTC)

If all the surface bacteria on your skin jumped up and down, how long would it take you to change direction? alteripse 18:39, 7 November 2005 (UTC)

May I BJAODN this question? Please?? :-) --HappyCamper 01:44, 8 November 2005 (UTC)
No, you may not. No matter how stupid the idea might seem to some, considering how long it takes educated people to figure it out, it is at least a useful mental excercise. The notion of conservation of energy appears to be a tricky one. I even for a second thought about constructing bridges at the equator so people could start running in one direction. If they were to keep this up long enough, the Earth's speed of rotation would change. Wrong! Only the acceleration wouyld have an effect and as soon as they stop, they would accelerate the other way and things would be back to normal. That is, if yo leave out friction, but then the unequality of mass (as calculated by Akamad) comes into play.
Another old idea is 'if all Chinese start jumping in unison they could conjure up earthquakes'. (with the epicentre proobabaly in China, by the way.) Now, we're talking about the mass of people vs the Earth's crust, which is just a fraction of the total mass of the Earth. And this is not about causing a change in motion, but about starting a vibration, which should be a lot easier. And even this is extremely unlikely. (Or is it?) DirkvdM 10:38, 8 November 2005 (UTC)
Yes it is; considering how much strain fault lines can accumulate before producing earthquakes, there's little humans can do to influence them, short of nuclear weapons.
Incidentally, I think HappyCamper is referring to alteripse's question, which is certainly silly enough to go to BJAODN; I don't think permission is really needed, regardless. The main question has amusing bits too, though; picture some demented South American walking over to the equator every day to jump one time, trying to make Earth spiral away out of the solar system... ‣ᓛᖁ♀ᑐ 11:26, 8 November 2005 (UTC)
Actually, the humour in Alteripse's remark distracts from the fact that it is a very useful comparison. Roughly (very roughly) the same discrepancy in dimensions is at work. The mass of bacteria on my skin is as minute compared to to the mass of my body as the mass of humans is compared to that of the Earth. It's just that one doesn't intuitively realise how vast the Earth is. I once made a remark to my mother along the lines that the Earth can't support the present human population and she took that literally, thinking the Earth might collapse. It then took a lot of explaining on my part to get that idea out of her head. As I'm now trying to get the idea of fervently jumping bacteria out of my head. :) DirkvdM 15:56, 8 November 2005 (UTC)

[edit] Why do planets rotate?

Hi! My friend and i were going through Einstein's Theory of relativity the other day and we found the whole idea of a space-time fabric fascinating. But this led us to a question-Einstein may have explained the whole reason behind the force of gravitation completely, but then there is an equally important aspect that he seemed to completely neglect-why do planets rotate? The moon and the sun rotate, but asteroids and comets don't? What is this special force that causes the rotation?If we can identify it, can we explain why Uranus rotates in the opposite direction to the other planets? Can we define a mass limit for planet rotation? I'll be very happy if someone can answer my query-I'm only in 11th Grade, so i won't really understand parts that are too complex. thanks 12:29, 7 November 2005 (UTC)~~

We were always taught that rotation of the planets is due to asteroid collision. The direction planets revolve in means that it is much more likely that the momentum from asteroid collisions spin one way. Venus and Uranus is an exception for unknown reason, probably fluke asteroid/comet collisions. smurrayinchester(User), (Talk) 12:54, 7 November 2005 (UTC)
Planets rotate because there's no force that would make them stop. As to why they started rotating in the first place, that's due to a number of effects during planet formation. The two major ones are:
  1. The protoplanetary disc was already rotating. As it coalesced into planets, all that angular momentum had to go somewhere.
  2. Even if the planets hadn't been rotating earlier, as the solar system gradually stabilized, the growing protoplanets often merged by collision. If a collision between two massive bodies doesn't happen to be exactly head on (and it's statistically unlikely to be so), the resulting merged object will have some residual angular momentum. If you don't believe me, try grabbing hold of a lamppost while running. Of course, you'll quickly come to a stop due to friction, but if you tried that in space with a really slippery lamppost, you'd keep spinning around it for as long as you could hold on.
Actually, there are tidal forces that do tend to slow the rotation of planets down. The moon, for example, always points the same face towards the earth because it's tidally locked. It used to rotate, but now it's effectively stopped. The same forces are slowing the earth down with respect to the moon, but since the earth is much bigger, it hasn't stopped yet and won't do so for a long time.
Also, asteroids and comets generally do rotate. The objects in the solar system that don't rotate tend to be those that are small and orbiting close to a another object, such as the inner moons of Jupiter and Saturn. Those are the objects which the tidal braking mentioned above effects most. Besides, strictly speaking even tidally locked objects do rotate, their rotation period just equals their orbital period. The moon, for example, rotates around its axis approximately once per month. —Ilmari Karonen (talk) 13:04, 7 November 2005 (UTC)

Thanks, GSJ. 13:51, 7 November 2005 (UTC)~~

I believe your second point doesn't hold true. Of course this would result in a rotation, but that could be either way, and don't planets have a tendency to all rotate in the same direction? (with Venus being an exception, Uranus an oddball (no pun intended) and Pluto strictly not a planet). I can't think of the reason myself (trying to make a comparison with the way atmosperic air rotates around high and low pressure zones), but my gut feeling tells me it has something to do with the solar system contracting (which would be in keeping with your preservation of angular momentum thing). DirkvdM 11:10, 8 November 2005 (UTC)
Yes, the collision hypothesis if often used to explain precisely those anomalous cases. (It should be noted, however, that other explanations for the anomalous rotation axes of Venus and Uranus have also been offered.) —Ilmari Karonen (talk) 13:09, 8 November 2005 (UTC)

[edit] Effect of solar wind on planetary orbits ?

The solar wind must push the planets out a bit further than their natural orbits (based on their orbital velocities). I would expect this effect to increase proportionally with the cross-sectional area of the planet, and decrease proportionally with the planet's mass, and decrease in proportion to the square of the planet's distance from the Sun. Now, a planet with a highly elliptical orbit would be expected to be pushed out more when closer to the Sun and less when further from the Sun. My question is, would this tend to make all orbits more circular over billions of years ? If so, I would expect the inner planets to make this adjustment more quickly than the outer planets. The innermost planet, Mercury, might have it's orbit disrupted by solar flares, etc., which could negate this effect.

Looking at the following chart, it does appear that the eccentricity of the planets Venus, Earth, and Mars follow the expected pattern:

Eccentricity..Planet
=========.======
0.20563069...Mercury
0.00677323...Venus
0.01671022...Earth
0.09341233...Mars
0.04839266...Jupiter
0.05415060...Saturn
0.04716771...Uranus
0.00858587...Neptune
0.24880766...Pluto

StuRat 15:01, 7 November 2005 (UTC)

It's easy to say 'maybe over billions of years' but without any quantification you are really shooting in the dark. Consider the potential for orbital ejection by the same force... over time we would see planets orbiting wildly away from the sun and eventually ejecting out of the solar system. Also, the idea that solar flares might cause irregular orbits, is interesting but it would only be remotely plausible if you could tie solar activity to orbital period, since the typically observed high activity times are measured in the tens of years, it would take consistent coincidence to cause the orbit of Mercury to warp even a tiny bit. There is data at spaceweather.com describing the measured solar winds... maybe you can cut some rough numbers with that to determine the force over time that is exerted? It's an interesting thought, no doubt. --Jmeden2000 19:14, 7 November 2005 (UTC)
I don't think the planets would be pushed progressively out of orbit, since their forward velocity would not be sufficient to maintain an orbit further out. Thus, they would try to "fall" back into their standard orbit more and more as they got farther out. Eventually an equilibrium point would be reached where this additional "weight" would be equal to the solar wind force and a stable orbit would be achieved. I will check out the site you listed. StuRat 19:41, 7 November 2005 (UTC)
The force from the solar wind should be inverse-square (since each planet intercepts a certain areal fraction of the total wind, assuming it's roughly isotropic). Since gravity is also inverse square, won't that make the net effect simply a (slightly) reduced gravitational force, without any circularizing effect? --Bob Mellish 20:41, 7 November 2005 (UTC)
So you're suggesting that the two forces balance each other and ultimately provide an equilibrium point? This would mean that there is a sort of seeking process that the orbit would perform, and upon realization they would attain an orbit slightly lower than what would be predicted using physics negating the solar wind. This would be an interesting mathematical test... how far off are the orbits and could that support the theory that the solar wind has a noticeable effect on it?

Ok, time for some calcs:

From: http://www.lgarde.com/people/papers/TESS/ (a site on solar sails)...

"The areal density, including payload, will be 3.63 g/m^2, giving a characteristic acceleration of 2.26 mm/sec^2" (0.00226 m/sec^2)

Earth's mass = 5.9736×10^24 kg = 5.9736×10^27 g

Earth's cross sectional area = piR^2 = pi(6,372.795 km)^2 = 127,587,980 km^2 = 1.2758798×10^14 m^2

Earth's areal mass = 5.9736×10^27 g / 1.2758798×10^14 m^2 = 4.882×10^13 g/m^2

Set up a proportion:

[3.62 g/m^2] / [4.882×10^13 g/m^2] = a / [0.00226 m/sec^2]

a = 1.676 ×10^(-16) m/s^2 (accel of the Earth if only solar wind was acting upon it)

v = 6.033 ×10^(-13) m/s hour (speed after 1 hour)

v = 1.448 ×10^(-11) m/s day (speed after 1 day)

v = 5.288 ×10^(-9) m/s year (speed after 1 year)

v = 5.288 m/s (speed after a billion years)

At that speed it would take about 1.8 years for the Earth's orbital radius to double.

So, I conclude that the solar wind is sufficient to have noticeable effects over time, if unbalanced. The Earth would have long ago been blown out of the solar system if this force was unbalanced regarding the mean orbital distance. My theory is that it is balanced, in the case of average orbital radius, but not in the case of eccentricity of the orbit, which should then even out over time. StuRat 23:46, 7 November 2005 (UTC)

[edit] Nuclear electric propulsion

What is Nuclear electric propulsion? How does it work? When can one expect it to be built?

Have a look at Nuclear electric rocket. Basically, it's electric propulsion (like an ion thruster) coupled with a nuclear power source (usually a nuclear reactor, but I suppose you could use RTGs). This makes it excellent for the outer planets, where solar panels aren't very effective.
In technical terms it's nothing incredible - space-qualified reactors have been built, as have electric propulsion systems - but designing and qualifying a system including both would take some time. There are also political aspects, as people are understandably antsy about putting nuclear reactors on any launcher with a 2% failure rate. I'm not aware of any current plans to use this propulsion method; the Jupiter Icy Moons Orbiter would have launched in about ten to fifteen years, using a nuclear-electric propulsion system, but it was effectively cancelled this summer. Shimgray | talk | 15:21, 7 November 2005 (UTC)


[edit] grasshopper

<No question posted>

Do you have a question, or do you just want me to try to pluck the stone from your hand ? StuRat 15:26, 7 November 2005 (UTC)

Perhaps grasshopper would help? Trollderella 17:17, 7 November 2005 (UTC)

[edit] Redhat 9.1

Can anyone recommend a good windows to Linux translation guide? My problem is that I just installed Redhat 9.1, and have absolutely no clue how to get to my external usb hard drives. I know that on windows I would go to my computer, and there is an icon called Home on the Redhat desktop, but it looks more like it contains system files. Is there a simple way to get it to automatically mount all connected drives? Thanks! Trollderella 17:07, 7 November 2005 (UTC)

I don't know Redhat 9.1 so I can only give you a few general Linux/Unixlike hints
  • Google for what you want to do and your distro version. 'automount redhat usb' gets more than enough I would think.
  • Assemble a few resources for answering questions like these, such as a good freenode Redhat channel or a few good Redhat 9.1 manuals/introductions that you've found from recommendations or google searching.
  • learn to use man pages (or other documentation that came with your system). On the console, man -k mount, should lead to some useful stuff. That said, Linux man pages are much less helpful/consistent overall than FreeBSD/OpenBSD ones I am more used to.
  • Find your local Linux user group if there is one. At meetings or on their mailing list people will generally be extremely friendly to newbie questions.
Hope that helps - Taxman Talk 21:09, 7 November 2005 (UTC)
After clicking on 'home' to open the file browser, do you have icons down the left side of the window? Is the bottom one 'Services' (hover over it and it will pop up a name)? If so, click on Services and expand the listing for 'Storage Media'. That is the best way for accessing the USB media that I know of because it doesn't have many bugs in the mounting and unmounting of external devices. Kainaw 21:15, 7 November 2005 (UTC)
Thanks! I'll take a look at those. I did do a bit of googling, but thought I must be getting it wrong that to mount a usbdrive I have to go into the command line and type something arcane. Trollderella 22:42, 7 November 2005 (UTC)
If you want everything to just work without having to tinker, and still want stability and ease of use, buy a Mac. The Mini is $500 of course if you have a monitor. Linux still requires between some and a lot of tinkering depending on the task. So if you want free (beer and libre) you'll have to accept that. It's getting better, but it's got a ways to go. Take that for the opinion it is, even though I can assure you it is informed. - Taxman Talk 00:42, 8 November 2005 (UTC)
Yeah, I'm with you, I'm really trying to make it work for me though... ;) I thought there might be a straightforward way to do this because I know that Knoppix does it. Also, I realise this is an old version of Linux - do you know whether FC3 has a way to figure this out?
I'm not quite a Linux expert, but this sort of thing is done in the fstab file (for 'file system table'), probably under /etc. I have a line that says
usbfs                /proc/bus/usb        usbfs      noauto                0 0

The 'noauto' says it is not automatically mounted (at /proc/bus/usb), but my usb CF card reader is mounted under media > usb-storage-000004728417:0:0:0p1, so I wonder what causes that. I use Suse with KDE. Is this done by KDE? If so, if you use KDE with RedHat it should work there too, right? DirkvdM 12:43, 8 November 2005 (UTC)

With Fedora Core 3 (Fedora is basically a beta-version of Redhat), USB was compiled into the kernel. So, the basic kernel operating system is handling the USB drive, not some outside module. I found this out the hard way. I had VMWare installed and I wanted to use USB with it. To do so, you must turn off the USB module in Linux. Since it is compiled into the kernel, the only way to do that is to recompile the kernel. I didn't want to mess with that, so I just gave up on using USB with VMWare. Kainaw 13:55, 8 November 2005 (UTC)
That "usbfs" entry is a little misleading. It actually doesn't have anything to do with mounting a USB storage device as a filesystem; it just provides a way for user programs to inspect the current USB configuration (browse through /proc/bus/usb if you want to see for yourself). As of the last time I used USB devices under Linux (about 6 months ago) mass storage devices were treated just like SCSI devices. Therefore, assuming you don't have a real SCSI card, the first USB storage device is /dev/sda1, the second is /dev/sdb1, and so forth.
I believe KDE does in fact handle mounting of removable devices; I've known it to automatically detect and mount CDs when I insert them. If you're not sure what's being mounted where, at any time you can type "mount" or "cat /proc/mounts" at a command prompt to view the current list of mount points and devices. —David Wahler (talk) 15:49, 8 November 2005 (UTC)
Ah, yes, I knew that, but had forgotten. Actually, I have two SATA drives, which are also named like scsi's, so they're sda and sdb, and the cardreader starts at sdc (through sdf because it can read four types of cards). I've even created mount points for them, but forgot about that since. Silly me. DirkvdM 16:07, 8 November 2005 (UTC)

[edit] legumes

What part of a legume is good fertilizer; every part of the plant, even the shells of peanuts for instance, or is it just the leaves and roots of the plant. --216.174.193.79 19:48, 7 November 2005 (UTC)

One of our patients is a peanut farmer. He said that the whole plant is high in nitrogen, but to get the best effect, rotate your main crop with your peanut crop. The peanuts will pack the soil with nitrogen so you can grow just about anything else (he rotates with cotton and soy). I'm sure there are online guides for optimal crop rotation sequences. Kainaw 20:08, 7 November 2005 (UTC)
Yes, peanuts have excellent value for crop rotation, that's why George Washington Carver worked to come up with recipes to find a use for all those peanuts. He came up with peanut butter and peanut brittle, among others. Before those ideas, peanuts were just considered something to feed livestock. StuRat 22:32, 7 November 2005 (UTC)


My understanding is that legumes augment the nitrogen content in soil by the action of symbiotic rhizobia bacteria, which aggregate in root nodules of the plant. --
Mark Bornfeld DDS
dentaltwins.com
Brooklyn, NY 19:04, 11 November 2005 (UTC)

[edit] Aquatic Mouse

Several years ago on That's Incredible! there was a segment featuring a lab mouse that had been modified such that it could breathe underwater (I think it somehow had gills added). Has there been any further research into this?

  • Are you sure it wasn't a regular mouse breathing a hyperoxygenated liquid, as seen in The Abyss (and apparently quite real? Edit: see liquid breathing) --Bob Mellish 20:43, 7 November 2005 (UTC)
Yes, that was it. StuRat 21:57, 7 November 2005 (UTC)

[edit] Big Brother World

Is the Echelon system the real Big Brother, IOW, the beggining of mass surveillance and control and the end of privacy? Or is it just a conspiracy theory?

It's not completely a theory. See ECHELON for more info. Dismas|(talk) 22:00, 7 November 2005 (UTC)
The real big brother have always been the secret services of countries. ECHELON is jut one of the arrows in their quiver, as the article says. But it's getting scarier now with the anti-terrorism excuse. Terrorism is said to be one of the major problems in the world (which it isn't) and that is used as an excuse for governments to spy on citizens even more. Worse though are what they do with the information, locking people up without a trial and such. Guantanamo Bay is just the tip of the iceberg (although it is a rather extremist tip). DirkvdM 13:04, 8 November 2005 (UTC)
I would say terrorism, which currently only kills thousands of people per year, is not yet a major problem, worldwide. However, it's potential to become a major problem must be considered. If terrorists manage to get their hands on nuclear or biological weapons, they would certainly use them, possibly killing millions and causing trillions of dollars in economic damage. Therefore, some reaction is justified. I won't comment upon whether ECHELON, specifically, is justified. StuRat 14:17, 8 November 2005 (UTC)
ECHELON or its equivalent have been around since long before terrorism was an issue. --Robert Merkel
True. I should say "I won't comment on whether the use of ECHELON to spy domestically, on your own people, is justified by the threat of terrorism". StuRat 21:24, 8 November 2005 (UTC)
Actually, what I meant to say is that the bad thing is what is done with the information. Being in favour of free information I can't see anything principally wrong with any form of information gathering. In an ideal world no-one should be worried about what other people know about them. Of course this works both ways. The NSA and the like are welcome to know anything about me that they wish, just as long as I have free access to any information about them, including the information they have gathered. But I don't see that happening. DirkvdM 07:51, 9 November 2005 (UTC)
Really ? That would mean a world without privacy or modesty, where a high-res photo of that mole on your genitals could be posted on billboards, along with which specific sex acts you've performed. You really think that would be a good thing ? Also, there is then no reason why we shouldn't give out the addresses of witnesses to Mafia hits, along with the times they will be alone and the house will be unguarded. I think most info should be shared freely, but some should be kept secret. StuRat 17:52, 10 November 2005 (UTC)
Ah, well, the witness thing is a good counterexample. And then there are instances where it's (at least practically) better to tell a lie. I'm still trying to figure out if it's true that those inoculations against the bird flu are meant not to prevent those people from getting the bird flu but any other infection, after which the two could combine to form a much more dangerous variation (lethal like birdflu, but more easily spread across humans). See Talk:H5N1#Reason_for_inoculations. If people knew this, they might no be bothered to get the inoculation, which might in the end be bad for them after all.
But I don't see a problem with privacy coming to an end. Why does the idea bother us now? Because we're used to privacy. If we were used to a lack of privacy then that would be normal and it wouldn't bother us. Unless it's not 'nurture' but 'nature'. And I don't see any indications for that. Although almost (almost) all people on Earth hide their genitals. Excuse me for getting biblical on you, but that is the symbol of the loss of paradise - the fig leaf. Mind you, I wouldn't feel comfortable with walking around naked, but I suppose that if everyone were to do it it would take me less than a month to fully adapt. A world without shame sounds like a good thing to me. DirkvdM 08:25, 11 November 2005 (UTC)

[edit] Burn Accelerators

Hello, I recently read that methane is not added to aid in the burning of the tobacco leaves for cigarettes but instead chemicals such as potassium citrate and sodium citrate are a couple of the chemicals added to act as a burn accelerator for cigarettes. Is this true?

Hey, cigarettes do contain about 599 additives including hydrogen cyanide.
I have heard that there are more than 640 additives in cigaretts. There are 2 GIF files around somewhere if you look, that is a reproduction of the two pages of additives that were released inder the freedom of informaiton act about the relationship between cigarettes and cancer. Potassoium Citrate and Sodium Citrate are among those reportedly added. Artoftransformation 02:53, 8 November 2005 (UTC)
The files about the contents might be at a place called 'Smoking Gun'

[edit] November 8

[edit] How do routers work

Hi

I want to know, specifically how a router works. I know that they are a layer 3 device that use IP addresses to forward packets onto other networks. But what I want to know - Can routers be assigned multiple IP addresses, so other sub-netted networks can use the same router? Or does every single different IP network need a new router to handle that task of forwarding packets onto other sub-netted networks? How do large organizations use routers in this case?

A router is not nessesarly a layer 3 device. ( see ISO Model ), and see ( Coyote Router)
Router's work by building tables of MAC addresses that are in assigned IP address ranges or assigning them an IP address, and recording the outgoing MAC adress, so that the router may edit the incoming packet, and change the IP header to mactch the requester, so that requests are routed to the right clients
A bridge is a router that translates addresses between two seperate IP address ranges.
Most common routers today are both Bridges and Routers, what used to be called Brouters are how just called routers.
Routers can be assigned, assign, and route multiple IP addresses with diffrent subnet masks.
My Router, a 486PC running Coyote Linux, can handle multiple subnets, on the same network. It doesnt have to be unique, but its a good idea, if your netmask is the same, or you will suffer packet loss. ( Its known as multi-netting and on clients its multi-homing )
Large corporations amd academic instutions, just buy a router/switch for every subnet, and most that have intelligent IT staff, design them with redundncy so that if a router starts misbehaivoing, they have a hot spare.
The best refrence I can think of for more informaiton is the two volume set of books 'TCP/IP.' It will tell you the secrets of Ping! Artoftransformation 03:18, 8 November 2005 (UTC)
  • However, if you do have two subnets sharing the same wire, many routers can be set up to recognise and route both of them. Ideally the router would also allow packets to be sent between the two subnets, even if it means sending a packet back out of the same interface by which it arrived. Notinasnaid 10:39, 8 November 2005 (UTC)

[edit] who discovered the element silver

Silver will tell you it's been known since antiquity. (In other words, nobody knows.) --jpgordon∇∆∇∆ 01:30, 8 November 2005 (UTC)

Who discovered that it was an element? Or was that evident as soon as the concept of elements was discovered? Trollderella 01:31, 8 November 2005 (UTC)
Probibly the Greeks were the first to assign the word 'Element' to componds that appeared to be pure. Artoftransformation 02:55, 8 November 2005 (UTC)
The modern concept of what an element is postdates a lot of elements.

Both this site and this site indicate that silver was discovered too early for the discoverer's name to be known. --Moriane 02:28, 8 November 2005 (UTC)

[edit] Origins of water

I heard a recent discussion on the radio about Comets & Asteroids. One of the contributors intimated that all the water on earth came from comets or asteroids colliding with our planet (and presumably melting). Apparently the elements for water would not or could not combine on earth without a vast input of energy. Any comments would be welcome.

It would disagree with allmost all other primordial earth theories, and contradict existing geological evidence to say 'ALL WATER CAME FROM ASTERIODS"
What primoridal Theories?
What Geological Evidence?
The excercise is left to the reader. Artoftransformation 02:47, 8 November 2005 (UTC)
Bull. Hydrogen gas, which was abundant in the early universe, bonds spontaneously with oxygen gas(less abundant but there for the same reason all other elements are here; nuclear fusion). Not only does it not require (net) energy, it releases it. Superm401 | Talk 03:55, 8 November 2005 (UTC)
I don't think it's right to say they bond spontaneously, it requires a spark or flame to get the reaction going. This could happen on the early Earth, from lightning and flames from volcanoes, etc.
The real question is, can the hydrogen bond with oxygen to form water before it rises to the top of the atmosphere and is blown out of the Earth's atmosphere by the solar wind ? This happens fairly quickly, which is why there is almost no hydrogen in the air we breathe. StuRat 14:09, 8 November 2005 (UTC)
I do not think the solar wind does this. Gas leaving the atmosphere is a function of the average energy of the molecule versus the gravity of the planet. This is why Hydrogen and Helium are rare in the earths atmophere.
Actually, they do bond spontaneously—just not at room temperature. —David Wahler (talk) 15:42, 8 November 2005 (UTC)
Then the question is if the temps on the primordial Earth were high enough for them to bond spontaneously. StuRat 16:23, 8 November 2005 (UTC)
The reaction is spontaneous in the sense that it has a negative change in Gibbs free energy. However, you're right that a small input energy is required. However, the input doesn't have to be much. It could just be a match's flame, or even the energy output from its own reaction. The early Earth was much hotter than it is now(it formed from a solar nebula), so I don't have any doubt there needn't have been a sudden input of external energy. Superm401 | Talk 03:51, 9 November 2005 (UTC)
From NASA [21]

"The component of primordial solids of major importance as a source for terrestrial water is hydroxyl ion. This ion forms a regular structural component in magnesium and iron hydroxysilicates, which form the major mass of carbonaceous chondrites of Type I (Wiik, 1956). (Crystal hydrates of magnesium and sodium sulfates found in carbonaceous chondrites are probably not generated in space where they are unstable; they are likely to be forming by reaction with water vapor in terrestrial museums.)"

"The fact that meteorite materials carry sufficient hydroxyl to account for the entire hydrosphere on Earth should not be taken to mean that the Earth formed from any of these specific materials, which probably represent different condensation events and regions in space. But the observations [487] imply that primordial condensates in different parts of the solar system, although varying markedly in chemical composition (ch. 20), have incorporated substantial amounts of volatiles, which were subsequently released in the accretional hot-spot front during the formation of the planets (sec. 26.3.2)."

Artoftransformation 05:02, 9 November 2005 (UTC)


A genius would translate the entry above so I could understand it.

  • The way I always heard it, the earth was full of highly reduced simple organic compounds, and lightning strikes and the rest caused small scale chemical changes over a very long period of time, ie chemical evolution, and the bit with the comits, was that since many have orbits that take them out beyond the Oort Cloud should still contain the same elements as the early universe, except trapped in deep freeze, not that the comits were the source--Hello'from'SPACE 23:34, 14 November 2005 (UTC)

[edit] Extra-Earth Vehicle Design

What should be design of Mars Rover?

Since the gravity of Mars is higher than the moon, It will have to be sturdier. The terrain of rocks seems ( from recent photos...) a bit rockier, but with about the same amount of sand hazards, it would have to have wheels with a bit of traction in them.
Remember the headlines about the Mars Rover getting stuck? and it took NASA a while to get it unstuck?
Here is NASAs website about the Mars Rover: [| Nasa Mars Rover ]
A major problem is that there is no direct feedback. If they give the vehicle an instruction to move, it will continue that move despite any unforseen problems that arise. So a cetain amount of autonomy (often erroneously called 'inteligence') is needed. Not just for safety, but also to make independent decisions about what might be an interresting direction to move in. And maybe even to do its own research. DirkvdM 13:11, 8 November 2005 (UTC)
It wouldn't necessarily need to have wheels - if you are designing one from scratch it could just as easily have a series of legs, like a spider, to aid climbing; or you could design one that moves like a snake for example. AllanHainey 13:43, 8 November 2005 (UTC)
It costs them so much to design a new rover, and they so often fail, that I think they would do best to make 100 more of the current model, which actually seems to work much better than expected. If they do eventually feel the need for a redesign, how about a blimp that could float around the planet and take close-up pictures of everything ? You could also give it the ability to drop and pick up rovers, if they need to take samples, be relocated, etc. Of course, this would require a degree of control of the blimp which may not be possible with current technology. Altitude could be controlled by solar heating of the "air" inside, say by painting the top black, and vents that could be opened or closed to cool the "air" inside. Solar cells would provide some electricity, but probably not enough for fans to control the direction. This would leave the blimp to drift in the prevailing winds, landing each night when the solar heating is lost. StuRat 20:53, 8 November 2005 (UTC)
Very interesting ideas( Brilliant actually ). How would a blimp work in an atmosphere that has 100th of the pressure? Artoftransformation 05:09, 9 November 2005 (UTC)
Well, it would have to be quite large and lightweight. Of course, only the flexible "balloon" and the payload would be shipped to Mars, it would inflate from the Martian atmosphere, using a slow but steady pump, driven off solar power. It might take many days to inflate. I would suggest multiple compartments, so the blimp will still work if some are punctured. StuRat 05:27, 9 November 2005 (UTC)

[edit] HIV/AIDS

what age group does hiv/aids affect the most?

  • In the UK, according to Avert.org, the most affected age group is 25-34 years, who account for "44% of all HIV diagnoses in the UK."
  • In India, according to Indian Business Thrust for HIV/AIDS "the spread is most in the age group 19-45 years."
  • UNICEF states that "Almost 12 million young people (aged 15-24) and 3 million children live with HIV or AIDS. The majority of new infections are among the young - 6,000 young people and almost 2,000 children become HIV-positive every day."
I guess regardless of whether the child or parent becomes infected with AIDS, the child is going to suffer greatly. So from that point of view, the young will always be more greatly affected by AIDS. Akamad 07:00, 8 November 2005 (UTC)


[edit] Huntington Rig

A Huntington Rig is for sailboats. It is used to lower and raise the mast singlehanded and keeps the mast in line with the boat. I have some information on it as I am designing a Huntington Rig for my 30' Marconi rig sailboat. What information do you have on this?

[edit] ADSL

The Wikipedia definition of ADSL says that the "A" stands for Asymmetric. However, I have been told that it can also stand for "Asynchronous". Is this correct, and, if so, is it a common variation?

Asynchronous Digital Subscriber Line got 460,000+ hits on Google vs. about 610,000+ for Asymmetric Digital Subscriber Line so I guess it's fairly common. Saikiri 10:40, 8 November 2005 (UTC)
Given how ADSL works, I would imagine that Asymmetric would be the correct one - after all, one of its most distinguishing characteristics is how it allows for much greater download than upload traffic. However, as Saikiri said, it seems both uses are common. — QuantumEleven | (talk) 11:19, 8 November 2005 (UTC)
As someone who had been in the communications business for 20+ years, I would go by the Wikipedia definition. ( and by the Google ranking also ). Synchronous refers to an alternative way of modem use, peticually with Mainframes of old. vs A-Synchronous, which is one direction at a time. This is how inexpensive dial up modems worked. Artoftransformation 15:53, 8 November 2005 (UTC)

[edit] Mathematical activity quantified

How many professional mathematicians are there, and how many mathematical articles are published each year? Related information would be useful as well. I'm having problems with Google on this one. Fredrik | talk 11:26, 8 November 2005 (UTC)

The question as posed is not really easy to answer, however somewhat acceptable gauges could possibly be found by going to the mathematical societies such as http://ams.org (American Mathematical Society) et.c. for the number of mathematicians or checking preprint services such as http://arxiv.org for article volume. If you'd be more interested in "respectable" articles, a better bet would be to see how many articles get reviewed each year, for instance in Mathematical reviews (http://www.ams.org/mr-database) or Zentralblatt Math (http://www.emis.de/ZMATH). Michiexile 09:34, 11 November 2005 (UTC)

[edit] computer meltdown!

My computer (Windows XP pro, AMD Athlon) has been with me for around three years. In the last year, it has buggered up four times. when booting up, out of the blue will come this message:

windows could not start because the following file or folder is corrupt or missing:
C:\WINDOWS\system32\config\system

This sucks, because when it happens my only option is to repair windows (by re-installing) which takes a while. the first three times it happened were worse, because all my preferences were gone and most of the programs had to be reinstalled. This time, I don't know why (because I followed the same procedure) but after repairing there was minimal setup, all preferences and programs were in place. But what I would rather is that this didn't happen again, any ideas? What I understand about the error message is that the file in question is a system file, it is 4.5Mb, and (I think) always in use (which means I can't copy the file and save it to disk for future issues). Any and all help is appreciated, thank you. --Ballchef 12:06, 8 November 2005 (UTC)

Can you start up from a CD and then copy that file? What I'm thinking is that the file wouldn't be in use since you'd have booted from the CD. 'Course, what do I know... I hate Windows and thus use a Mac.  :-) Dismas|(talk) 13:18, 8 November 2005 (UTC)
Same here, except I use Linux. :) Anyway, a major problem with WinXP is that it is supposed to be stable, which it isn't. At least with Win98 you could save a working version and then when it crashed, simply copy that to the same drive (you'd need another working OS to do this copying, but that can also be another copy of that same working installation that you normally never use and will therefore not become unstable). I've used this method for years and it worked just fine. But with WinXP it doesn't work (and the built-in recovery utility doesn't work either because it will throw away any save you made after a while). And Linux is stable. So there are two alternatives in case you have to reinstall and don't want this to happen again. By the way, this isn't a computer meltdown, it's just msWindows, but I assume you knew that. DirkvdM 13:23, 8 November 2005 (UTC)
Hi Dirk. Please stick to answering the questions rather than pimping Linux. Proto t c 14:26, 8 November 2005 (UTC)
Or Win98. Please don't read my answer selectively. :) True, though, I didn't answer the question, but I offered two alternatives in case he didn't manage to solve the problem. I'm sorry if telling a relevant truth looks like pimping Linux. That's one up for Linux, I suppose. :) DirkvdM 16:16, 8 November 2005 (UTC)
One of the downsides of linux is that many of its users are raging zealots who cannot have a single conversation without celebrating their own awesomeness. It seems like these drones are capable only of saying "use linux" to any computer query on this page. -Lethe | Talk 18:15, 8 November 2005 (UTC)
Well, as a raging anti-zelobot, there are some people who can relate to this. We need to stop the pimpin, and anti-pimpin, and constructivly help this person. --Artoftransformation 05:35, 14 November 2005 (UTC)
Of whom I am not one, because I gave two alternative suggestions, one being Linux, the other being Win98. Why don't you then bitch about me pushing Win98? Might it be that you are biased? Oh, sorry, I forgot, being biased toward msWindows is not a bias because that is 'normal' :) . DirkvdM 15:15, 10 November 2005 (UTC)

DUH! This is WHY I took the damn Class.... INSTALL THE RECOVERY CONSOLE. Using the recovery console it allows you to COPY critical system files to other backup directories. Artoftransformation 16:11, 8 November 2005 (UTC)

Did you try booting in a diagnostic mode using the F8 Key? Did you try copying the file from the command prompt? That file is a key component of your operating system. (Windows XP) if it becomes corrupt, then you do have to start from scratch. The user:Proto makes a good case. You can find a windows root kit CD, with Linux on it, and boot from that, and copy and back up your OS. ( I have my hard disk partitioned, so I have both the restore XP CD, and the OS backup ready and avaible. I would think that your hard disk is getting old, or that you have hit some security problem with XP, with all the recent updates, and you may need to back your OS up. ( btw, I use XP, with a FAT32 formated partitoin for the OS, and a NTFS partition for my documents. )(And I have a 2 iMacs, and a Linux box within reach. )( Also within reach is a emergency boot CD, Knoppix live CD with root kit tools on it) Artoftransformation 16:11, 8 November 2005 (UTC)
Also my computer dual boots Windows XP Pro, and Windows 98, according to these instructions: [[22]]. If you boot from Win 98 on floppy, AND your OS partition is FAT32, then you can copy the C:\WINDOWS\system32\config\system to a backup, and restore it when it gets corrupted. Artoftransformation 16:11, 8 November 2005 (UTC)
Also Go to AMDs website and install their AGP Miniport driver:

[[23]] Artoftransformation 16:20, 8 November 2005 (UTC)

How fast is your processor? 16:20, 8 November 2005 (UTC)
Only 1Ghz faster than yours --
After edit conflict:
Hey, that was me, who suggested making a backup copy of the OS, not Proto (the Linux hater :) ). But I also said that it didn't work for WinXP. Now that was a year ago (I only had it running for a month or two when it crashed), so I can't remember what the problem was. But you say you've got WinXP running on FAT? I didn't think that would be possible (I mean that a microsoft product could be so flexible :) - sorry). Maybe that would be the solution (I need Photoshop and Win98 is really too old). But how do you do that? Can you specify it during installation? DirkvdM 16:28, 8 November 2005 (UTC)
Who said Linux Hater? Imo have to hurt them :P. Dude. I partitioned the drive, at least the first 3.25Gb of a 120GB drive with my Win98 Boot disk(FAT32). Foratted the partition, and copied the WinXP CD There. Then you boot from the CD, and run the installer from the HD. Fast Fast Fast. After I got the thing up and running, I ran all the XP SPs from another CD, that I had collected them onto. (What LIVE on the Internet with out SPs? Id rather be flogged ). Got the wholething running, and installed FireFox.
As you may know, I DO NOT have folder level securtiy auiditing, but I do have volume level security, and none of those ADS Streams. What version of Photoshop? CS2 requires 'Microsoft® Windows® 2000 with Service Pack 4, or Windows XP with Service Pack 1 or 2' Artoftransformation 05:25, 14 November 2005 (UTC)
Thanks for the tip. I'll give it a go (when I find the time, way too much of which goes into Wikipedia). I use PS 6.0. Having PS work (any version) is more important than having a recent version because once you're used to PS, all the other image editors are a big letdown (keyboard shortcuts, to name just one thing). DirkvdM 09:20, 14 November 2005 (UTC)

2. If this happens who knows what else is broken; I would recommend a full reinstall of everything. 3. If your backup system was up to the job, you wouldn't need to ask - you'd just recover last night's backup while enjoying a nice cup of tea. Or two... Notinasnaid 17:22, 8 November 2005 (UTC)

Well thanks for some of the most complicated answers i have seen in a long time. I have previously tried many of your solutions, and whilst XP is crap[UNDSTATEMENT], I can't be bothered changing just yet. Thanks to all, but special thanks to Notinasnaid for the link to the windows website. This seems to address the problem (although it's complicated) so I will do as Windows orders me to. thanks. --Ballchef 01:10, 9 November 2005 (UTC)

The "C:\WINDOWS\system32\config\system" file is part of the Windows registry, and is essential for the funtioning of XP. Reinstalling will put a default version of the registry in its place (customised for your hardware, but not for your applications). This will give you a booting machine, but many of your applications will need to be reinstalled.
I'm assuming you don't have system restore turned on. This feature makes periodic backups of the registry and other key system files and will roll back to earlier versions if they become corrupt. Its designed for exactly this situation. I believe that it can take up excessive disk space but there's a slider in the "Control Panel/System/System Restore" control applet to limit that (mine is set to about 600 MB at the moment on a 40 GB disk). IF you do have system restore operating, try selecting "Last known good" from the boot menu. You may have to press F8 as the system boots to see that boot menu. Even if you don't think you had system restore working, you have little to lose now by selecting "Last known good" as at worst it will give you a similar system to a reinstall.
An even better solution is to use a disk imaging utility (such as Ghost (software)) to make occasional backups of your system drive to another drive.-gadfium 01:33, 9 November 2005 (UTC)
SYSTEM is not part of the registry. Its the Operating System, main rentrant executable. You can rebuild a Registry. You cannot rebuild this file.
As I said, system restore doesn't quite work that well. I remember now that I tried it and the 'last known good' didn't work, nor any previous ones. And since it automatically makes backups and then knocks out the oldest ones (fifo), I had lost the one version I wanted to keep because it had the basics right and I hadn't installed any try-out software, which I do quite a lot - maybe that's where the problem lies. But if the copying thing works for WinXP installed in a fat partition, I might give WinXP another go. DirkvdM 08:10, 9 November 2005 (UTC)
Your the master of understatement. After System Restore didnt work at all for getting rid of a trojan, I have never used it again. Artoftransformation 05:25, 14 November 2005 (UTC)
According to X-Setup Pro, a program that deals with making registry changes, it says that SYSTEM is a part of the registry. Just throwing that out there. And about the computer problem, i agree that you should try to select "last known good" from the boot menu. --Shardsofmetal [ Talk | Contribs ] 23:45, 14 November 2005 (UTC)

[edit] It's a bit chilly

Is it harmful to be exposed to an uncomfortably cold environment (but still well above freezing… say maybe 7-10°C/45-50°F) for an extended period of time? Garrett Albright 18:02, 8 November 2005 (UTC)

If it's cold enough, you'll end up with chronic hypothermia. If it's warm enough for the body's heat regulation to keep the core body temperature normal, however, I'd expect you'd be fine. The threshold of "warn enough" is probably highly variable depending a person's age, body mass index and general health, plus external factors like humidity and wind chill. —Ilmari Karonen (talk) 18:25, 8 November 2005 (UTC)
Short of hypothermia, other problems could be caused by the cold. Shivering and other warming responses use up a lot of energy, so you would be likely to starve if you didn't increase your calories accordingly (but the hunger response will normally take care of this). Also, the slow moving circulation in your extremities could provide less blood flow to fight infections, repair cuts, etc. One other factor is the low humidity common at low temps, which could cause dry skin, chapped lips, etc. StuRat 19:03, 8 November 2005 (UTC)
I'd have throught that "warm enough" would also depend on a person's background - I suspect that a person from Greenland would be "warm enough" at lower temperatures than someone from Panama. Thryduulf 18:59, 8 November 2005 (UTC)
That's true. People who've lived in those climates for many generations tend to have an extra thick layer of fat, and short extremities, which really helps with the cold. StuRat 19:10, 8 November 2005 (UTC)
Of course that depends on the clothing you wear, unless by 'exposed' you mean totally naked (in which case the amount of bodily hair would come into play). I wonder if frostbite could occur at such temperatures. If the body can only just keep the vital organs (all in the rump, except for the brain) at operating temperature it will basically leave other parts of the body to die because the alternative would be for the entire body to die. I just don't know at what temperature that would start to happen. DirkvdM 08:33, 9 November 2005 (UTC)
The answer depends on a few factors: The rate of heat generation (is the subject able to do physical exercise), The rate of heat loss (is the subject well clothed, is it raining, whats the temperature), and the amount of time the subject is in the cold environment. If the rate of heat generation is greater than or equal to the rate of heat loss, then the answer is yes (e.g. someone slowly running for a day even in shorts and a shirt will stay warm even if it is quite cold. Of course they'd have to stop eventually). If the rate of heat loss is greater than heat generated, hypothermia will set in eventually. Frostbite can occur when the temperature is greater than freezing, but only if there are other factors in play, e.g. person with restricted circulation who is wet and in a strong wind. In this case they are likely to get hypothermia first! --Dumbo1 17:34, 10 November 2005 (UTC)
Thanks for the replies, all. Garrett Albright 07:11, 11 November 2005 (UTC)

[edit] Widescreen TV

Will my Full screen VHS tape and DVD's still work with a Widescreen TV?

If you mean playing tapes/DVDs with a 4:3 aspect ratio on a TV with a 16:9 aspect ratio, then yes you can. How they are displayed will depend on the setting your TV is on - on the widescreen TV we have, there is a choice of viewing them in the original 4:3 ratio (i.e. with black bars down the sides), or stretched to 16:9. Some TVs stretch the entire image, but others (and I presume most modern ones) stretch the edges of the image more than the centre. From experience the only time you notice this is when you switch between them.
If you mean will you be able to record widescreen TV to VHS and/or DVD, my understanding is that this is possible if they are connected by a SCART lead, but not if the connection is by standard co-axial cable. Thryduulf 19:09, 8 November 2005 (UTC)
I suppose that by that last bit you mean when using the tv's receiver to record on an auxiliary machine. But if the cable goes from the wall to the recorder (and from there to the tv), then I assume the recordings will be wide-screen. I wonder, though, if recordings of wide screen transmissions on an old recorder will also be wide screen. I don't see modern recorders advertising with that, so I assume the oldies will record it too. DirkvdM 08:40, 9 November 2005 (UTC)

[edit] Digital Cable

Is it possible to record something on digital cable without a DVR?

Yes, but it is not possible to record a digital cable channel other than the one you are watching, at least with a standard system. Thryduulf 19:09, 8 November 2005 (UTC)

If it is possible do it, How do you do it?

Just use a VCR or whatever you have, plug it into your cable box and start recording. Or am I misunderstanding your question? —David Wahler (talk) 21:58, 8 November 2005 (UTC)
The only problem you might face is Macrovision; ways to defeat that are mentioned in the article. --Robert Merkel 22:17, 9 November 2005 (UTC)

[edit] The Burning Question

This question goes back to burning in cigarettes, what does the alternative cigarettes use to make their smokes burn since they don't use tobacco leaves?

What? Cigarettes are full of tobacco, and a lot of other things. If you must smoke, smoke cigars. Dominick (ŤαĿĶ) 19:48, 8 November 2005 (UTC)

No, they have some that are filled with things like a blend of smoking herbs: Marshmallow, Yerba Santa, Damiana, Passion Flower, Jasmine and Ginseng. If there is no tobacco or nicotine what chemical aids these herbs in burning?

also the shredded Clove. Clove Cigarettes, also called kreteks contain 60~70 percent tobacco, but According to the U.S. Centers for Disease Control and Prevention (CDC), Clove Cigarettes produce at least twice as much nicotine, tar, and carbon monoxide as regular American cigarettes brands.
To answer your question directly, almost all 'alternative cigarettes' us some form of dried plant matter, that burns rather easily (compared to an ice cube, which is already oxidized).) Its only the Tobacco Cigarettes that contain as many as 640 chemicals to aid them in burning, so that they wont go out. Artoftransformation 02:54, 9 November 2005 (UTC)
Cigarettes don't burn because of nicotine... I mean, burning is just any reaction with oxygen. Oil burns, wood burns... Anything {Plant matter} dried and cut up into fine bits or powder would burn very well.--Fangz 21:04, 8 November 2005 (UTC)
Not quite everything will burn that way, it has to be something that can oxidize. Fiberglass, for example, won't burn. StuRat 21:20, 8 November 2005 (UTC)
I misunderstood the use of the word alternative. Clove cigarettes for example. They burn quite well, and stink to boot. I think they burn like any dried flammable organic matter would burn. I imagine you can make cow pie cigarettes, they may smell better than the clove variety. My opinion is those alternatives blow even bigger holes in your lungs than tobacco. {Which is supported by the CDC} Clove Oil is a great tooth anesthetic, and I have heard that people do a lot of violence to the lungs without feeling a thing. Anything that is burned and inhaled will deposit junk that doesn't belong in your lungs. I still would suggest cigars as a better alternative. Dominick (ŤαĿĶ) 21:31, 8 November 2005 (UTC)
Clove cigarettes (to clear up an apparent misunderstanding) are loaded with tobacco; they aren't 100% clove. There's no evidence at all that clove cigarettes are more harmful than standard tobacco cigarettes, though there were some dramatic urban legends circulating about it (mostly due to some dumb kid who insisted on smoking while recovering from some respiratory ailment.) Signed, ex-two-pack-a-day clove smoker. --jpgordon∇∆∇∆ 23:44, 8 November 2005 (UTC)

All these things can burn but not well, I agree. But is there specific chemicals added to these herbs or leaves that aid in their burning to make the burn slower and better?

  • The last thing the cig manufacturers want is for them to burn slower. --jpgordon∇∆∇∆ 23:45, 8 November 2005 (UTC)
Dominick, why would cigars be any better? I assume that's usually the case because cigar smoke is usually not inhaled. But I do inhale it. When in Cuba I started smoking cigars. After two weeks I had some lung infection. So I stopped smoking cigars (which was a letdown because they taste soooo much better - especially the big Cuban ones). DirkvdM 08:47, 9 November 2005 (UTC)

Most dried leaves (including tobacco) burn pretty badly on their own. Commercial cigarettes tend to be doped with saltpeter and glycerin to make them burn more steadily, and save you having to relight them. The only thing keeping a hand-rolled plain leaf cigarette burning is the paper and an occasional relight. The burn will also depend on how you roll it - how densely packed, how fat the cigarette is. But for commercial herbal cigarettes, I imagine they would be doped with glycerin and saltpeter like commercial tobacco cigarettes.84.43.1.92 11:01, 14 November 2005 (UTC)

[edit] skin effect article

I'm researching the skin effect and referenced the article so titled. Digging through the equations in various articles, I see several examples provided for copper at various frequencies.

Replicating the table should be straight forward. Using articles found under "Resistivity" and "Permeability (electromagetism)" and "angular frequency", I find that the formulas provided do not work with the sample tables provided in the various articles.

My suspicion is that the units between the articles are messed up and not comparable.

For example:

Copper wire at 10kHz is indicated as a skin depth of 0.66 mm.

Using resistivity of copper as 1.7 x 10^-8 (table in resistivity article

Angular velocity of 2pi/(1/10000)= 62831.85 (formula in angular velocity article)

Permeability of copper as 1.256629 (table in permeability article)

The result is 8.24-7 and no definition of units is described.

The table in Skin Effect indicates 0.66mm

What gives?

Why did you use angular velocity? Skin effect from tables is an exponential effect, current tends to travel and vary exponentially as you go into a conductor. Dominick (ŤαĿĶ) 21:33, 8 November 2005 (UTC)

Good question. The Skin Effect article describes the depth as d=sqrt(2p/wu) where w is angualr frequency of current=2pi x freq.

[edit] Moon

What is the frame of reference that makes a moon crescent appear to be on its side? Any why is that this position appears to change over the course of an evening? --John

I'm not sure if I understand your question, but the Moon rotates around the Earth in an elliptical orbit that is tilted 5° to the ecliptic, and the Moon rotates once a month (roughly), which translates into a movement of about 13° each day along the zodiac of the celestial sphere. Was that what you were asking? Titoxd(?!?) 23:53, 8 November 2005 (UTC)

My question is specifically in regards to the moon cresent: sometime it appears in a "vertical" position, at other times it appears in a more "horizontal" position.

A form of libration, perhaps? Shimgray | talk | 00:15, 9 November 2005 (UTC)
It might also have to do with latitude and the altitude of the Moon on the sky: [24] Titoxd(?!?) 00:22, 9 November 2005 (UTC)

No, no, no. This is simple: the lit side of the moon is lit by sunlight, so the lit side is always oriented directly toward the sun. With a crescent moon, this means that the inside of the crescent is oriented directly away from the sun. Draw a line from the center of the dark edge through the center of the lit edge and onward, and it points to the sun.

You can verify this by eye if you look at the moon in the daytime; of course, you must be careful not to hurt your eyes by staring at the sun. Similarly at night, the lit side of the moon points to wherever the sun is below the horizon, on its path (as seen from the earth's surface) from the sunset point back to the sunrise point. Note incidentally that this means that the unlit side of the moon is always the upward side, at night: if you see it any other way in a movie, you know they faked it and got it wrong. --Anonymous, 01:20 UTC, November 9, 2005

Indeed so. -- Ec5618 01:29, 9 November 2005 (UTC)
The simplest situation is at the equator, where, the Moon moves roughly overhead (and the Sun 'underfoot'). There, the crest is horizontal. I haven't observed this back home (the Netherlands), but I assume the same would happen here during summer, when they also move overhead. Your statement that this changes overnight puzzled me at first, but I suppose that has to do with what you regard as the vertical. When the Moon is at its highest point you'll observe it correctly, but before and after that you should really tilt your head to align the imaginary line through your eyes with the horizon under the Moon at its position at that moment. At least, that seems a reasonable explanation. Visualising three dimensions can be almost impossible when curvatures come into play.
By the way, I thought that this could be seen in the flags of some countries nearer the equator, but in the List_of_flags the only such flag I see is that of Mauritania. Shouldn't, say, the Maldives have it horizontal too? DirkvdM 09:11, 9 November 2005 (UTC)
How about answer the question directly? The Frame of refrence to the occurance of the phases of the moon, is you are standing on a fixed point on a rotating ball[Earth] watching a reflected object[Moon, with high Albedo], reflecting the light of the Sun. Since your frame of refrence is the unlit side of the earth, The lit surface always appears as a cresent with the concave pointing up, at night, since the sun is beneath the horizion. During the day, the cresent points away from the sun. The position changes over the course of an evening, because the earth rotates, the moon orbits slightly, and the earth orbits even slightlier.

[[25]]

--Artoftransformation 05:43, 14 November 2005 (UTC)

You should try and find yourself a moonie they worship the moon or something, so they should know a lot about it--152.163.101.12 05:46, 14 November 2005 (UTC)

[edit] November 9

[edit] Hydrocarbon energy content

Why are HCs the primamry choice for energy generation?

Economics, portability and distrubution:

Petrolium products are cheap.
Petrolium products can be carred long distances independantly.
Petrolium products have a large distrubution network in the United States. ( Gas stations, and refineries )

There are costs that are associated with its use:

The amount of CO2 as a biproduct is indicated as a cause of global warming.
The byproducts of inefficent burning, relase HCs into the air, casuing polltion.
The source of HCs is not renewable. Artoftransformation 02:35, 9 November 2005 (UTC)
Hydrocarbons provide a very dense source of energy based on volume. Hydrogen gas, on the other hand, takes up far more space than gasoline, if you want to provide the same total amount of energy. This would require a rather large fuel tank on a car. StuRat 03:38, 9 November 2005 (UTC)
For stationary energy generation, such as in a power plant, cost is the only one of the factors mentioned hereabove that applies. Wind- and solar energy have the disadvantage that they're not reliable (the amount of wind and sun varies). But many countries (including the US) have several places where there is always sun and the land is cheap. There is still a cost-factor, but I suppose the big difference is that the investments in the use of oil have already been made. If we didn't have that, and a choice would now have to be made, the fact that oil needs to be distributed and we'd have to build the distribution network might prove to be prohibitively expensive. I suppose that, like England after its industrial revolution, we're now stuck with a different kind of dialectics of progress (that's the translation my dictionary gives for the Dutch term 'remmende voorsprong' - it is mentioned towards the end of [26]). DirkvdM 09:32, 9 November 2005 (UTC)

[edit] Byung Chan Eu

I am trying to find a publisher who has copies of Byung Chan Eu's lifelong work on thermodynamics, statistical mechanics, generalized hydrodynamics, et cetera...However, after a while of searching, I cannot seem to obtain copy of them. May I leverage the expertise of the reference desk to see if there are better ways to obtain these rare but priceless books? --HappyCamper 04:09, 9 November 2005 (UTC)

I found four books by this author on http://www.abebooks.com/ (which is basically a directory of 13,000 used booksellers). Also, I have no personal experience of this site, but it found at least one of his books: http://www.campusi.com/. Another tip is to Google for the ISBN of books. Notinasnaid 09:52, 9 November 2005 (UTC)

[edit] Oral bacteria, dogs v. humans

Who's mouths are "dirtier" human's or dogs?

While there's a popular idea that a dog's mouth is cleaner, that doesn't make much sense if you think about it. Dog's don't have any oral hygiene, we humans do. You'd expect a human to brush his teeth at least one time every day. Also, dogs constantly chew on random objects from the ground, and also lick several 'dirty' things. We humans don't do that (well, at least it's not a common practice!). So, I'd say all evidence points to the fact the human mouth is a lot cleaner, just because we don't put anything we find in there, and we do try to keep it clean. ☢ Ҡieff⌇↯ 05:10, 9 November 2005 (UTC)
I would think the biggest factor would be the size of the mouth. Most dogs have larger mouths, so I would expect more bacteria, all things being equal. However, perhaps there are fewer bacteria in a dogs mouth, which might cause a problem for humans, since many of the bacteria would not be able to cross the species barrier and infect humans. StuRat 05:21, 9 November 2005 (UTC)
Interestingly enough, Mythbusters tested this very myth, in Episode 39, and according to them, a dog's mouth is cleaner. Akamad 05:43, 9 November 2005 (UTC)
Kieff, aren't your assumptions a bit outdated? About half a century ago there was this notion that one couldn't use enough detergents and pesticides and what have you. Nature is dirty and full of diseases, so we have to erase it from our environment. At the risk of sounding like a hippie, we're part of nature and nature is part of us. Too much 'cleanliness' can lead to all sorts of problems, such as allergies. And brushing your teeth too often is bad for the protective layers, including benevolent bacteria that keep the 'bad bacteria' out. So it's a matter of definition of 'dirty'. If by that you mean disease-ridden (or alt least -prone) it may very well be that a human who brushes his teeth (hard) more than once every few days has a dirtier mouth. Also, wouldn't chewing on all sorts of things be good for the teeth? Basically, that's what a toothbrush is an alternative for. It may just be too thourough.
By this reasoning, the fact that dogs have less bacteria in their mouths doens't necessarily mean they're 'cleaner'. It's just a matter of what kind of bacteria. And what might be fine for a human might be a potential pathogen for dogs and vice versa. DirkvdM 09:48, 9 November 2005 (UTC)

Also, how many bacteria could mean "total bacteria count" or "number of bacteria species". StuRat 13:41, 9 November 2005 (UTC)

Something else that must be considered (along with the definition of 'dirtier') is what natural processes are in place to control bacteria. Both dogs and humans have mouths that are very receptive to bacteria, they are warm, dark, wet, and often nutritious. But saliva and other processes are there to limit bacteria growth. If you compared it to 'what goes in must come out' then a dog's mouth, rarely being externally sanitized, and very often ingesting many different types of bacteria, must wind up with more bacteria (i.e. be 'dirtier'). For a complete analysis, its important to consider the limiting factors before coming to a conclusion. I too saw the Mythbusters ep featuring a bac-culture test on a dogs tongue vs a humans, and they were strictly testing individual bacteria count over a surface, when cultured on agar. This is a good way to do just that, test individual bacteria count. It had no bearing on overall bacteria count (although the numbers would be somewhat related) and had no bearing on the type of bacteria (slow/fast growth, pathogenic to mammals, etc) so it's not really fair to conclude anything from that except how much bacteria is on your tongue that happen to like agar. --Jmeden2000 17:28, 9 November 2005 (UTC)


I will have to defer to the opinion of a veterinary expert regarding the cleanliness of dogs' mouths. However, I can assert authoritatively that the quantity of oral microbial biomass varies greatly from person to person. Intuitively, it makes sense that the same variation applies to dogs.
Also keep in mind that the distribution of microbes in the oral cavity is not uniform, so a simple sampling from one source area will not yield a figure that will realistically translate into either total bacterial count or bacterial density per surface area or volume. For example, bacteria tend to aggregate on tooth surfaces adjacent to gingival (gum) tissue, and in the papillae that stud the dorsal surface of the tongue. In contrast, bacteria are relatively few on the smooth enamel surfaces near the chewing sides of the teeth.
The oral cavity presents as an open ecosystem, with microorganisms of many different types (bacteria, protozoans, fungi, viruses, and monera) that each fill an ecological niche. Into this ecosystem are introduced both nutrients that support microbial growth (i.e., food), and exogenous microbes from the outside environment. Complicating matters are the oral defense mechanisms that come into play. These include the continual exfoliation of surface epithelium from the oral soft tissues, the mechanical flushing of microbes down the alimentary tract by swallowing of saliva, the antimicrobial effect of salivary enzymes such as cellulase and antibodies such as secretory IgA. The dynamics of these systems vary greatly between individuals within a given species, much less between the species under comparison. For example, the rate of salivary flow, the salivary IgA titer, or the rate of epithelial exfolation varies greatly from time to time in a single individual; that is why most human mouths feel so dirty on first awakening from sleep.
In sum, it is a practical impossibility to assess whether any mouth consistently has more bacteria than any other, either within or across species lines.

--
Mark Bornfeld DDS
dentaltwins.com
Brooklyn, NY 23:42, 9 November 2005 (UTC)

Yuk, I've got a bunch of ecological niches in my mouth. :)
Thanks for the expert contribution. DirkvdM 08:57, 11 November 2005 (UTC)
Dont kiss your dog, after he has been drinking out of your commode. They are not as selective in their hygene or diet. --Artoftransformation 05:45, 14 November 2005 (UTC)

[edit] caterpillar paradox?

The developmental stages of organisms sometimes reflect aspects of the biological history of the species. The organism's earlier evolutionary forms would have been superseded by its later, modified physiology; thus, its earlier forms would have passed into redundancy, expressed only as 'shadows' of previously existing physiology. Taking the butterfly as an example, during the time that it was evolving wings, it would have 'left behind' its previous wingless form - it would not have lived part of its life as a wingless orgasm, then after metamorphosis changed into a partly winged creature (its evolving into a fully winged creature not having been completed yet). The butterfly's present developmental stages seem to show the expression of both the current final stage of evolutionary development as well as the earlier segmented caterpillar form being carried along in tandem as a fully functioning organism (albeit as a defined developmental stage). Why didn't the earlier physiological form of the organism, i.e. the caterpillar, get sloughed off and consigned to its evolutionary history?

Dudley Warrington

"The developmental stages of organisms sometimes reflect aspects of the biological history of the species" - this sounds like ontogeny recapitulates phylogeny, which is now broadly discredited (though many textbooks still keep it, sadly). Shimgray | talk | 16:28, 9 November 2005 (UTC)
Not commenting on the theory claimed above, I would say the caterpillar stage is necessary since butterfly/moth wings, which are relatively rigid and covered in scales, don't work on the small scale of a creature that would pop out of a butterfly egg. Other types of wings do work on that scale, however, so a two-stage, or multi-stage, life form with different wings and aerodynamics might work. Perhaps in a few million years such a creature will evolve. StuRat 16:58, 9 November 2005 (UTC)
Butterflies lay small eggs. Each egg becomes a caterpillar, which put on a great deal of weight by eating leaves or similar vegetable matter (which are very common). After it has gained weight it pupates and emerges as a fully grown adult butterfly. Once a butterfly, the animal does not moult and therefore stays the same size. If the egg were to develop into a butterfly directly, the emerging butterfly would have to go through a series of moults to attain adult size, (butterflies don't moult once they have reached imago. Aerodynamics at the scale of a butterfly are very different from aerodynamics of a creature emerging from something the size of a butterfly egg.
Here's a thought. Considering that the caterpillar is meant for growth and the butterfly for reproduction, could you say that a butterfly is a caterpillar's flower (just like a mushroom could be seen as a fungus' flower)? DirkvdM 09:16, 11 November 2005 (UTC)
Well, moths and butterflies aren't just for reproduction, they also eat (drink, to be more accurate) and migrate. StuRat 20:15, 11 November 2005 (UTC)

Thanks for the insights and contributions . I suppose I'm essentially asking what evolutionary mechanism leads to the development of the metamorphosis stage, without the organism evolving out of its earlier form (as expressed by the caterpillar). DW.

The talk.origins FAW briefly mentions the intermediate stages to metamorphosis known to exist [27], and cites a Nature paper which sounds quite interesting. I have a suspicion Stephen Jay Gould will have written an essay on this - it's definitely his sort of thing - but I don't know offhand; if he had, that'll be a good summary for a nonspecialist. Shimgray | talk | 14:21, 11 November 2005 (UTC)

[edit] An inside out boiled egg?

I guess the egg yolk has a higher relative density than the egg white.

What will happen if I spin an egg fast enough and long enough? Can I turn the egg inside out? Do I need to poke a little hole on the egg yolk to break the membrane at first?

Currently I don't have a suitable tool at home (I'd like to modify a tabletop fan). Maybe I can boil an inverted egg this way. -- Toytoy 14:27, 9 November 2005 (UTC)

This thing is already invented - to cook eggs. Basically, you crack the eggs and pour them into a canister. The canister is spun (by water convection acting on fins), and the result is a central yolk and exterior white - just like a regular egg. --Commander Keane 16:29, 9 November 2005 (UTC)
I remember seeing that! Alphax τεχ 05:39, 10 November 2005 (UTC)
Dremmel Tools go 10,000 RPM. Now how about the design of a Egg Holder, that would not crack an egg going 10,000 RPM. Centerfuge 69.181.232.116 02:00, 10 November 2005 (UTC)
Unless you got it perfectly balanced, the system would be unstable and Bad Things would happen. Alphax τεχ 05:39, 10 November 2005 (UTC)
Anyone has access to a high speed centrifuge? I think the components of an egg will separate into layers in the test tube. If you spin the content of an egg in an artificial egg-shaped container fast enough and long enough, and then boil it, I guess you may get a rock hard protein outer layer and a watery core.
Possibly the rock hard protein outer layer would be a band around the egg's equator. the axial column would be hot water.
I need a slow spinner. No, I need some eggs. ... I forgot to buy eggs yesterday. I need eggs. I need my daily dose of cholesterol. -- Toytoy 09:43, 10 November 2005 (UTC)
We do have a centrifuge in my dept at uni (for soil testing mainly). I don't know what qualifes as fast, but it's big and noisy. I suppose I could bribe a phd student with beer and gain access. But I thought the invention I pointed to earlier (which I saw on TV too Alphax) indicated that the white is denser than the yolk. It spun around, and the yolk went to the middle. Am I confused?--Commander Keane 11:37, 10 November 2005 (UTC)

[edit] how do we store info in our brains?

i mean when i read a word in a book for the first time how this word gets stored inside my brain ? nerves or what? and where it is stored? and in which form it is stored?

You could start by checking our article on memory. ☢ Ҡieff⌇↯ 15:15, 9 November 2005 (UTC)
See also visual system. --Ancheta Wis 03:21, 10 November 2005 (UTC)

and another question if the eye has artries and veins branched into capillaries why cant we see them? or sometimes we see only red ones??why dont we see dark red ones ?

The quick explanation is that the blood vessels in the eye are located in the choroid, which lies underneath the retina. Except under certain unusual illumination conditions, there isn't enough light reflected back from the choroidal blood vessels up into the retina for us to see them. TenOfAllTrades(talk) 15:08, 9 November 2005 (UTC)
Also, the cornea doesn't have blood vessels at all because they'd tamper with our vision clarity. See our article on cornea for more information ☢ Ҡieff⌇↯ 15:15, 9 November 2005 (UTC)
You can see them, by shining a light in your eye in the right way. You'll cause internal reflections and see the veins. — Omegatron 15:48, 9 November 2005 (UTC)

[edit] Is the Da Vincci Code for real? Does it exist?

It is a work of fiction. The author took elements from real people and events, and wove a tale of fiction. If you look for yourself, you can see Opus Dei is quite different from the book. Dominick (ŤαĿĶ)

Read The Da Vinci Code. Dominick (ŤαĿĶ) 16:09, 9 November 2005 (UTC)

The idea that the holy grail is actually the bloodline of Jesus and Mary Magdelene is a real theory, though obviously an unproven one. In fact many of the historical and artistic references cited in the story are real. There are still standing debates over certain topics like "The Last Supper (Leonardo)" and others, and as for the cryptex, it is an invention of the author, not of Da Vinci. He actually does a very clever job interweaving true and false subjects into a work of fiction. But in essence, thats what it is, a work of fiction. - Cobra Ky (talk, contribs) 17:13, 9 November 2005 (UTC)

[edit] Low sodium saline solution ?

My brother is on a low salt diet due to high blood pressure. He recently had surgery which required that he get his fluids via saline solution. However, the sodium content in the saline caused his BP to spike dangerously. When he complained to the nurses, they said they only had one concentration of saline solution for patients. Is this true in general, or do lower concentrations exist for patients on reduced sodium diets ? StuRat 17:32, 9 November 2005 (UTC)

I asked a nurse and a doctor here. The nurse said there's only one concentration purchased and every hospital she's worked at only has one concentration. The doctor was more informative. He said that they use isotonic saline (as opposed to hyperbolic). The difference between the two is rather interesting. With infections, the body's serum sodium drops. So, a hyperbolic solution will help increase it. Isotonic, on the other hand, has been accused of lowering the body's serum sodium level.
So, you can google for isotonic, hyperbolic, and serum sodium levels. Perhaps you'll find something you want. Kainaw 19:26, 9 November 2005 (UTC)
Ok, thanks for the lead. Does anybody here know any more about those two types, how they regulate sodium levels, and when each is used ? StuRat 20:16, 9 November 2005 (UTC)
Another doc just told me that 3% is used. The reason is that it is the lowest level to create a proper solutions. Some chemicals aren't solulable in water, but are in 3% saline solution. Again, I know nothing about this. I'm just repeating whatever I'm told. Kainaw 21:09, 9 November 2005 (UTC)
I have no idea what was intended by "lowest level to create a proper solution" but this statement is not correct.alteripse 13:08, 10 November 2005 (UTC)
3% seems really high, it would take very little at that concentration to hit the Recommended Daily Allowance for sodium. I can see why that would cause a problem. Do you know if that's 3% sodium or 3% NaCl ? And I assume that's by weight ? StuRat 01:06, 10 November 2005 (UTC)
Tomato juice (with salt added) is about the saltiest thing I ever drink, and it runs around 0.2% sodium, by weight. Are you sure saline is 3.0% ? Perhaps you meant 0.3% ? StuRat 01:17, 10 November 2005 (UTC)
3% saline is used in low volumes to treat severe euvolemic or hypervolemic hyponatremia. alteripse 13:08, 10 November 2005 (UTC)
Ok, this might be the problem, they may have used the 3% saline in high volumes, improperly. He had an immediate salty taste in his mouth and spike in BP whenever they administered the saline. It sounds as if they should have been using the 0.3% concentration saline (see comments below) for general fluid replacement. StuRat 13:48, 10 November 2005 (UTC)

No, no, no. None of that info about saline concentration is relevant to your brother's blood pressure. BP does not respond acutely to saline and there are a number of risks from giving a hospitalized patient a hypotonic saline solution. The far more likely causes of acute high bp include pain, immobility, stress, discontinuation of home meds, accurate detection of higher bp than expected, and some other things. This is not the place to second guess your brother's treatment. alteripse 22:17, 9 November 2005 (UTC)

Sodium is known to rapidly increase BP. And this is the proper place to ask if multiple concentrations/formulations of saline solution are available in hospitals. StuRat 00:59, 10 November 2005 (UTC)
Saline only rapidly increases the BP when the patient is in hypovolemic shock. Otherwise the effect is relatively small, and in nearly all cases is primarily an effect of the fluid volume infused, not the Na content. While the information given about the different fluids was mostly true, no one bothered to tell the inquirer that he was making a very misguided assumption-- that choice of saline concentration was the likely cause of his brother's BP problems. This is not the way to answer medical questions here. Finally, the controversial association of long-term high-salt diet and high prevalence of hypertension in a population is not relevant to this acute situation. alteripse 11:45, 10 November 2005 (UTC)
  • For a human body to function properly one needs to have normal saline which is the solution of 0.9% w/v of NaCl in water. - Mgm|(talk) 10:09, 10 November 2005 (UTC)
For a human body to function properly it needs a Na concentration in the extracellular fluid of 0.9% (i.e., "normal"), which does not mean that the best fluid to put into your body in most circumstances is normal saline. Actual fluid and electrolyte needs for a healthy adult whose only intake is intravenous can be matched more closely by about 1/3 normal saline, because we lose water by more routes than we excrete salt. alteripse 13:08, 10 November 2005 (UTC)
Does "1/3 normal saline" mean 1/3 of 0.9%, so 0.3% ? If so, that seems more in line with what seems reasonable to me. This is because any liquid beyond 0.3% sodium, by weight, taken orally seeems "too salty" and is unpleasant to drink. This, I believe, is the body's warning that the sodium concentration is too high. StuRat 14:00, 10 November 2005 (UTC)
"Sodium is known to rapidly increase BP"? I thought the state of play was more accurately described by this quote: "Studies of groups of people throughout the world build a strong association between high blood pressure and eating large amounts of salt. However, research has not established whether or not a high-salt diet causes high blood pressure." Is this inaccurate? I personally resent the demand that I eat less salt because of a statistical risk to my health, but that's not really relevant – I would like to find out some more information that hasn't been oversimplied as "eat less salt". Is there a Wikipedia article on dietary sodium? Notinasnaid 10:13, 10 November 2005 (UTC)
There is also a statistical association between drinking alcohol before driving and dying of a car accident. Do you resent people who tell you not to? alteripse 13:08, 10 November 2005 (UTC)
I think it would be impolite of me to discuss this further in someone else's thread, much as I am itching to do so... Notinasnaid 20:12, 10 November 2005 (UTC)

IV normal saline solution contains sodium at the same concentration as exists the blood. The cells in your body expect a certain ambient sodium concentration, and get upset if you muck with that. (Too low results in hyponatremia). To simplify, IV fluid with low sodium concentration will be driven by osmosis into the body's cells; it won't stay in circulation where it presumably is wanted. The salt in normal saline won't cause a spike in blood pressure when administered, because it's at the same concentration as what's already in the blood.

There are other things that may have caused the spike in blood pressure. Your brother can and should speak to his surgeon or his physician about them. (To pull one random example off the top of my head, I might ask if he received any sort of locally injected anaesthetic immediately before his BP went up. Lidocaine, for instance, contains a small amount of epinephrine to increase its effectiveness. However, if by random chance and bad luck the local injection hits a vein rather than just soft tissue, the spike of ephinephrine in the blood will cause increased heart rate, sweating, nervousness—the whole fight-or-flight response.) TenOfAllTrades(talk) 12:36, 10 November 2005 (UTC)

In your statement "the salt in normal saline won't cause a spike in blood pressure when administered, because it's at the same concentration as what's already in the blood", you assumed they used the proper saline solution. I suspect they were using the 3% saline solution mentioned above, which has an improperly high sodium content (for general fluids replacement usage). The immediate and alarming results happened each time they turned on the saline drip. He ended up cutting off the saline drip and sipping water instead (against doctors orders), to replace his fluids. StuRat 14:16, 10 November 2005 (UTC)
This type of epinephrine effect would be over in minutes because of the small amount. The pain effect of surgery on BP would last hours or more. alteripse 13:08, 10 November 2005 (UTC)
It seems to me that if you have made your mind up that something is going to be bad for you, then it is likely to cause stress, and may increase your blood pressure. So an interesting, but unlikely to occur, experiment would be to have the patient's blood pressure measured after getting a saline drip, and also after getting a drip composed of pure water. It also seems to me that if it did have this effect, that increased blood pressure is not generally immediately fatal, and a hospital is well placed to deal with its effects, just like the many other undesirable effects of the (presumably) necessary procedure. I would still really like to see a reference to back up "Sodium is known to rapidly increase BP". Not because I know enough to categorically disagree, but because I haven't heard it before and it seems to contradict other stuff I have read; and would like to know more. Notinasnaid 20:12, 10 November 2005 (UTC)

I don't believe he was expecting the worst, at least not from the saline solution. Admitedly, the surgery itself may have made him nervous, though. Here's a good source: [28]. This particular passage relates to my brother's case:

"....a large subset of patients with essential hypertension responds to salt loading and restriction with pronounced changes in blood pressure, which has led to the concept of salt sensitivity." StuRat 20:28, 10 November 2005 (UTC)

StuRat, I forgot you were the questioner and it was your brother. I still think an iv fluid error an extremely improbable explanation. In the US 3% saline usually comes in different sized bags, with red or bold labeling and often is not stored on the same ward supply shelves. It is very rarely used and would be an unlikely error, especilally since there are so many more common causes of sudden high BP in a hospitalized adult. alteripse 22:03, 10 November 2005 (UTC)

I still think it's possible. Let me explain. He had surgery for an infection which had eaten through the wall of the cesium (he had a section of the intestinal wall removed). Based on the earlier post: "With infections, the body's serum sodium drops. So, a hyperbolic solution will help increase it."
I think they may have put him on the 3% saline, meaning it to be a temporary measure to increase low sodium levels. Then, perhaps after a shift change, the new nurse didn't realize that 3% saline was in the drip, and continued to administer it as if it was normal saline. Sounds plausible to me. StuRat 20:07, 11 November 2005 (UTC)

[edit] Question: Define Production Configuration v. Stored Configuration

Good day.

I'm beginning work on a project - BPM - and I'm working with folks in IT. I've been doing a little research around Configuration Management and Change Management. I've run across these terms in an article discussing the benefits of Config. Management and the author mentioned these two terms in context of what might be tracked and managed.

I've not been able to find a reference that defines the diference between these two states.

Can you point me in the right direction?

Thanks.

Change management is for an existing system for which changes must be tracked. Configuration management and Software configuration management (SCM) are the more general case for both new and existing systems. In other words, a production configuration is for an existing configuration, because no one in his right mind would go to production without a pilot plant. A Stored configuration is something which existed in the past, with possibly a list of the capabilities that it offered. Someone experienced would also be able to list the deficiencies in both the Stored and Existing configurations. The changes are tested against Regression tests and the successes/failures are tracked in one of these systems as well. In other words you need multiple configurations to get anything done nowadays. Ancheta Wis 23:15, 9 November 2005 (UTC) P.S. I was thrilled to see that Marc Rochkind himself has corrected some entries in History of software configuration management. He is one of the originators of this field.

[edit] Setting up a shared calendar

What's the best way to set up a shared calendar for a media prep room? Several people need to submit the dates that they need things (media for labs - like agar plates or bacterial cultures) to a single person who would then merge the files into a single master calendar. And - it needs to be something a non-tech-savvy person can handle. Any suggestions? Thanks. Guettarda 20:23, 9 November 2005 (UTC)

Making a private Yahoo group will give you a calendar, message board, and file storage area. Kainaw 21:12, 9 November 2005 (UTC)
A decidedly low-tech approach would be to put a clipboard and paper sign-up list on the door and have people sign in there. It works well if everyone is physically in the same office, but not well if some are out of the office regulalry. Perhaps each person could list a requested item and requested date, then the technician could fill in an estimated date, and finally fill in a completed date, once done. StuRat 21:13, 9 November 2005 (UTC)

[edit] Atolls

How do atolls form?

Read atoll Kainaw 21:07, 9 November 2005 (UTC)
Good name for a tropical island: "Not-bad atoll". StuRat 21:19, 9 November 2005 (UTC)
And an answer-man can retire to "Know atoll". --Ancheta Wis 23:07, 9 November 2005 (UTC)
If you go over a bridge to get to one, you might have to "Pay atoll". Sigh. Don't worry, puns don't "Hurt atoll". --Fastfission 01:52, 10 November 2005 (UTC)
We need to be serious here, people need answers. Cut it out. I don't like this "atoll". (Not enough coconut trees and polynesian girls!) Dominick (ŤαĿĶ) 13:25, 10 November 2005 (UTC)
Sometimes getting people to stay on track is "atoll" order. Johntex\talk 17:49, 10 November 2005 (UTC)
And if you stick around on the Ref Desk for a long time, you build up atoll-erance for bad jokes. Garrett Albright 07:08, 11 November 2005 (UTC)

[edit] plutonium

How many protons, neutrons and electrons are in plutonium (subatomic particles)

See plutonium, and keep in mind that an element always has the same number of protons, but the number of neutrons varies by isotope, and the number of electrons varies by ion. StuRat 21:34, 9 November 2005 (UTC)

[edit] November 10

[edit] Hypothermia

Why is hypothermia often accompanied by hyperkalemia? ‣ᓛᖁ♀ᑐ 00:27, 10 November 2005 (UTC)

Any process that leads to tissue breakdown releases K from inside cells into the extracellular fluid. alteripse 00:48, 10 November 2005 (UTC)

Case study. Hypothermia-induced hypokalemia by A. W. Zydlewski and J. A. Hasbargen. Hypokalemia was observed during hypothermia. "Upon rewarming, severe hyperkalemia occurred with resultant fatal arrhythmias. Severe hypokalemia may be seen in hypothermic patients, which represents a shift of potassium rather than a true loss."

--JWSchmidt 01:40, 10 November 2005 (UTC)

[edit] Touch-activated lamps

How do those "magic" lamps that turn on and off when you touch them work? Does it have something to do with grounding? —Keenan Pepper 01:42, 10 November 2005 (UTC)

It has to do with the change in capacitance induced by your hand when you touch the surface. The lamp has a special circuit which detects this, so it knows when to turn it on or off. --HappyCamper 01:45, 10 November 2005 (UTC)
If it had to do with grounding, it would be the same as sticking your finger in a power point, ie. you would be electrocuted. I remember building a "touch-activated switch" once - there are a couple of transistors in a debouncing switch setup; the electrical "noise" of touching the wire attached to the base of the transistor is enough to switch the circuit on. Alphax τεχ 05:42, 10 November 2005 (UTC)
One could design a system where the user must be grounded to set off a switch, when touching an object. That is, it is possible for a person's body to conduct a quantity of electricity which is sufficient to be detected, but not sufficient to cause any damage (or even sensation). Of course, for a lamp, the capacitance method is far superior, since the person touching the lamp would rarely be grounded. StuRat 13:32, 10 November 2005 (UTC)
Kind of a cool thing to do with these touch-activated lamps: line up a chain of about 4-5 people, all touching hands, the one nearest the lamp keeping his/her hand upon the lamp, and the person at the end of the chain can activate the lamp by touching the person on the chain nearest them. This in itself will tell you it has something to do with capacitance. - Cobra Ky (talk, contribs) 19:09, 10 November 2005 (UTC)

[edit] A paper - J. Res. Nat. Bur. Stand. 40, 163, (1948)

Can someone help me decipher what the abbreviations mean? I'm trying to figure out what paper this is: J. Res. Nat. Bur. Stand. 40, 163, (1948) Woolley. --HappyCamper 02:08, 10 November 2005 (UTC)

Journal of Research of the National Bureau of Standards. This would be a US government publication. The National Bureau of Standards still exists. alteripse 02:11, 10 November 2005 (UTC)

Thanks Alteripse, that was a big help. Now, what's irritating for me is that I can find volume 40, but not the correct page!! [29] - could someone help me find the correct page online? It should contain tables of thermodynamic data for molecular oxygen. --HappyCamper 03:03, 10 November 2005 (UTC)

[edit] Cryptography, and paths to studying it

I'm interested in finding out what someone who wants to be a cryptologist would study. I'm guessing a lot of math, but do universities offer a major called "cryptology," or is it a combination of other disciplines? I can't seem to glean an answer from either the portal or related pages. --Impaciente 03:27, 10 November 2005 (UTC)

Well, at my university there are a few maths subjects called "coding and cryptology"... it's an applied mathematics subject and if you did major in crytology, it would be as part of a maths/computer science degree. Of course, the information you can get out of such a course is probably no more than if you just when and read a few textbooks on the subject and talked to the right people. What kind of crypto are you interested in? A friend of mine has just done some heavy geometry and reckon they know enough from that to be able to do ECC... Alphax τεχ 05:28, 10 November 2005 (UTC)
Read Singh's "The Code Book", decrypt the codes in the back, and then realize that cryptology is mostly very boring, but continue trying to factor RSA-640... damn, someone did that already! --Kainaw (talk) 15:50, 10 November 2005 (UTC)
Have a read through our cryptography articles-check the Category:Cryptography for a list of them. We have a lot and they are generally of high quality and that should give you enough of an overview. I agree with Alphax on the course path you would take. Whether you would emphasize the math theory or the computing side would depend on what you wanted to do with it, but you would certainly need a fair amount of both. In much advanced cryptography the math is at the level of an advanced Masters degree or above. I would disagree that the only thing you would get out of such a course of study is what you could read from a book. The thorough grounding in theory and methods you would get from the years of advanced math study would allow you to work at a much higher level than someone without it. You could of course learn most of that for yourself from books, but few people have the dedication to do that so consistently on their own. I would also disagree with Kainaw that it is very boring, as many people find it one of the most interesting areas of applied math/computing. Whether it is worth it to you, you'll have to decide for yourself. - Taxman Talk 16:41, 10 November 2005 (UTC)
Thanks a lot for your help fellows. I'd love to study the subject, along with anything else math related. Unfortunately, I haven't been blessed with the noggin for numbers; I just find them utterly fascinating. Alas, I've had to settle for political "science." ;-) --Impaciente 18:33, 10 November 2005 (UTC)

Is there much money in cryptography? Broken S 20:56, 10 November 2005 (UTC)

O ei;d o,shomr yjrtr#d ;pys. niy pm;u og pm;u og upi str trs;;u brtu v;rbrt Proto t c 11:53, 11 November 2005 (UTC)

[edit] soccer ball

How many hexagons and pentagons are in an official soccer ball?

There are 12 pentagons and 20 hexagons. :-) See truncated icosahedron too. --HappyCamper 04:12, 10 November 2005 (UTC)

[edit] Nature vs. Nurture: Homosexuality

I was wondering if there was a place on wp (or the internet at large) that lists some of the arguments for nature or nurture, with particular regard to homosexuality? This isn't for an assignment, I'm just wondering. --ParkerHiggins 04:22, 10 November 2005 (UTC)

Sure, have you tried reading our article on homosexuality and the articles linked from it? --Robert Merkel 05:20, 10 November 2005 (UTC)
Also find a discussion in the 2nd paragraph of the "In biology" section of randomness: StuRat 13:22, 10 November 2005 (UTC)

[edit] Database problem (from helpdesk-l)

Note: The original post is available here

Hello,
Our IT people have been having problems loading the dbase IV programs on to the newer computer that has Windows XP. (We had some of the same problems is 2000, when updates were being done). Is there a Windows (2003, Professional, NT) software that supports the Dbase programs better?
I used to be able to copy and paste, rename a file, dump the data and re-enter the "new" data using the previous editing programs. I can no longer do this with XP. Or I can get one data base copied, recognized but not the 2nd dbase, nor the editing programs. Do you have any ideas on how to make this function? Would purchasing a newer version of dbase be more compatible with the XP.
We are also talking about converting to SQL all of our older dbase data ( we have ~ 30 + years).
Is this a feasible thing to do? Have you heard of this being accomplished successfully?
Perhaps you can direct me to a guru who has accomplished these feats.
Thank you for your time and any help you can offer.

Alphax τεχ 05:32, 10 November 2005 (UTC)

[edit] Meteors and meteorites

Roughly what proportion of meteors reach the ground without completely burning up, and so become meteorites?

Having a quick look at this Cornell University page, it seems rather difficult to actually get accurate figures on the number of meteorite strikes. Akamad 08:47, 10 November 2005 (UTC)

[edit] Biology: Mosquitoes

Why do mosquitoes lay eggs singly?--155.232.250.19 10:39, 10 November 2005 (UTC) Why do mosquitoes lay a large number of eggs?--155.232.250.19 10:39, 10 November 2005 (UTC)

The best explanation for the second question is that laying a large number of eggs is an r-selection reproductive strategy. Many species produce an enormous excess of gametes or offspring because only a few will survive. This is true for most insect species, and for most species that deposit gametes or young in a risky environment. In this reproductive strategy the parent invests almost nothing in the way of effort or food in the rearing, and most perish. The opposite is called K-selection, where only a small number of offspring are produced but the parents continue to invest large effort or food resources into rearing the offspring and a high proportion survive. alteripse 11:37, 10 November 2005 (UTC)

[edit] Aproximation of sine function with bezier spline

Since a bezier spline can't correctly define a perfect sine function (unless you use a indefinite number of control points), then what's the best aproximation I can get of a sine curve ([0,2π]) using a bezier spline? I'm thinking of at most 6 control points for the basic "arch" shape. I'm trying to find some formula for this, but it's been kinda tricky for me. I wanna find this to create some SVG files, and I just need it to be as accurate as possible.

Besides, it's some nice math to work with and learn from, so... Anyone can help? ☢ Ҡieff⌇↯ 10:41, 10 November 2005 (UTC)

  • Can't give you a mathematical reasoning behind it, but I've found using the points (0,0), (0.5,0.5), (1.0,1.0), (π/2,1.0) as a cubic bezier work very well for the [0,π/2] part of sine. Flip and extend them for the whole curve. --Bob Mellish 15:44, 10 November 2005 (UTC)
    • The cubic polynomial can be a good approximation of the sine curve in the [0,pi/2] interval, but I couldn't find the ideal coefficients for this either. I thought it could be some light on the issue, but apparently it's just another interesting problem to solve ☢ Ҡieff⌇↯ 20:18, 10 November 2005 (UTC)

[edit] what is the use of the leaves of the african tulip tree

see photosynthesis and do your own homework--Goshawk 14:00, 10 November 2005 (UTC)

  • We were missing the appropriate redirect here; African tulip tree now points correctly to Spathodea. Our article is very short and doesn't mention the leaves; if you ever figure out what's special about them, please feel free to add it to the article. -- Creidieki 18:33, 10 November 2005 (UTC)

[edit] Electric toothbrush

Long ago I used to have an electric toothbrush. Now, I always wondered how this think recharged itself, as there are now metal connectors between the toothbrush and the recharger? How does it work? --R.Koot 13:50, 10 November 2005 (UTC)

  • For more information, visit the HowStuffWorks article on how electric toothbrushes recharge. HowStuffWorks is a very useful resource. Hope this helps, Shardsofmetal [ Talk | Contribs ] 23:50, 14 November 2005 (UTC)

[edit] Object Oriented Programming - Scripting languages (PHP & ASP)

What are the purposes and uses of integratwd development environment (IDE) --209.88.91.212 14:06, 10 November 2005 (UTC)

Integrated(TM) Development Environment(R) will lower the TCO, while increasing the ROI of doing your own homework. --R.Koot 14:17, 10 November 2005 (UTC)

[edit] superposition theorem

I was wondering exactly what the superposition theorem is. All i know about it is that it is used in circuits because my circuit thoery teacher is having us do problems dealing with the superposition theorem. If you could list what it is and how it is used to solve circuits (or equations, i dont really know) i would greatly appreciate it.

--Jacob

The idea behind the superposition theorem is that the response of a circuit to multiple sources can be determined by determining the response to each source whilst the rest are turned off, and then summing the results.
So for example, if you have a circuit with a voltage and current source and you want to determine the voltage drops across a resistor. You can first, replace the current source with an open circuit (but keep the volage source in) and calculate the voltage drop across the resistor. Then replace the voltage source with a short circuit (and putting back the current source), and calculate the voltage drop. Then simply add the two voltage drops across the resistor and that is your answer.
Hope that helps. Akamad 00:31, 11 November 2005 (UTC)

[edit] Will a UK PC game work in the US?

Yes. PC games do not have region controls. However, you may run into problems with certain online games, for example, MMORPGs.
Of course, for driving games, you may have to drive on the "wrong side" of the road to avoid accidents. StuRat 17:33, 10 November 2005 (UTC)
Unless you're into that sort of thing, in which case either side of the road is fine--Reference(www.com) 20:41, 10 November 2005 (UTC)

[edit] Effects of geomagnetism on human health

Are there known effects of geomagnetism on human health? Does the consideration of geomagnetism currently enter into medical practice? If so, does medical practice vary from nation to nation in this respect?

There is no reason to assume the geomagnetic field has any effect on human health. Not only is the field incredibly weak, but there is no credible way for the magnetism to affect the body, as the body contains no small magnetic particles that could be affected. -- Ec5618 17:04, 10 November 2005 (UTC)
Well, extremely powerful magnetic fields, like the ones used in particle accelerators, can rip the iron-containing hemoglobin out of the red blood cells and potentially kill someone. There are also some indications that long-term exposure to strong electro-magnetic fields, such as by those living under high-tension power lines, may cause some chronic health problems, like cancer. But, the Earth's magnetic field is far too weak for there to be any such effect. StuRat 20:08, 10 November 2005 (UTC)
No they can't, those are urban legands, electromagnets can't affect heme binding affinity, and the only thing that happens when you live near power lines is you wind up breathing a lot of ozone, which can affect your health--Reference(www.com) 20:39, 10 November 2005 (UTC)
Yep, in answer to your original 3 questions: no, no, and no. --Dumbo1 17:06, 10 November 2005 (UTC)

Since this effect has been around long before life began then any evolving life form that was adversely affected by your normal everyday geomagnetism would have died out long ago.--Eye 21:55, 13 November 2005 (UTC)

[edit] The inverted hard-boiled eggs (Part II)

I saw this egg-inverting trick in a Japanese sushi manga:

  • Hero: A nice sushi chef with a all the skills and a pea-sized brain.
  • His opponent: Another skillful chef that we dislike.
  • An old con man with a chicken.

The hero was in his restaurant when the old guy came. He said: "I'll sell you a chicken that lays inverted eggs." Our hero did not buy his words. So the old guy boiled an egg and opened it. Our hero was amazed to find the egg really has yolk on the outside and the white inside. He paid 100,000 Japanese Yen and accepted the chicken only to find out a week later, that chicken was a cock.

The old guy came to the other chef. This time he taught that chef the trick for 200,000 Yen so he can challenge our hero.

Our hero was totally hopeless. He went to his sushi teacher, only to find out his master tried to make it according to an antique cookbook while he was young. The book taught him to preserve the eggs in miso and rice bran. No, it didn't work.

At the day of the match, the bad chef made a sushi with an inverted chicken egg. People were amazed. However, our hero made a sushi with inverted multiple quail eggs. The bad chef said to himself, "It's hard for me to do it with a large chicken egg. How could he make it with quail eggs?"

  • The con man's trick:
Kids, do try this at home!
Kids, do try this at home!
  1. Take a paperclip, straighten it and bend it so it looks like an upside down right half of "Y". Make a small right angle at the tip of the half "Y".
  2. Poke a little hole on the top of the egg.
  3. Insert the clip and spin it with your fingers until you feel increased resistance and the yolk flows out from the hole.
  4. Seal the egg and hard boil it.

(You may want to use a large egg.)

  • The hero's invention:
  1. Poke a little hole on the top of the egg.
  2. Drain its egg white.
  3. Poke the yolk so it breaks apart.
  4. Seal the egg and shake it.
  5. Boil it slowly while letting it roll in the water.
  6. Use a syringe to reinject the egg white.
  7. Boil the egg again.

(You may want to use a very small egg so the yolk adheres to the shell more evenly.)

Well, I plan to try it at home. I guess it is a magician's trick. But I know I am too clumsy. I can never be a good chef. The manga author said the egg white tend to adhere to the metal. I don't buy his theory. The only alternative explaination I can think of is the centrifugal force. So I guess I could do it with spinning. -- Toytoy 16:32, 10 November 2005 (UTC)

If you try and succeed, could you please take a picture of it and add it to an article here, say inverted egg? --HappyCamper 01:06, 11 November 2005 (UTC)
Tried the paperclip trick. Failed on my first try. Sorry, my first name is not Thomas and my last name is not Edison and I hate failures. However, the yolk does move to the side of the egg without touching the egg shell. The egg is still edible, though. -- Toytoy 13:13, 11 November 2005 (UTC)
  • I figured this was about the thing where you stand an egg on it's narrow end, and balances, but only when the moon and the sun are lined up in the same gravitational pull, the equinox, this seems to be something else--Hello'from'SPACE 23:40, 14 November 2005 (UTC)/

[edit] Digital Radio

Hello, Digital radio is getting a lot of press & is very popular, despite the fact that the sound quality isn't as good as is purported, however I have always suspected that the fact that it is digital rather than analogue means that it is easier for it to be blocked or jammed by national governments. Is this the case. If all radio had been digital in WWII would radio free France & radio free Poland, etc have been able to get through? or would they have been easily blocked (more easily than the Nazis were able to block the analogue radio transmissions)?

Thanks AllanHainey 16:45, 10 November 2005 (UTC)

My first thought is that digital is less easy to block. Error correction is possible on a digital signal, which isn't on an analogue. DJ Clayworth 20:28, 10 November 2005 (UTC)
Analogue error correction is quite possible. Dysprosia 02:19, 11 November 2005 (UTC)

[edit] Denoting a carriage return at the command prompt

Hi, I am using a pywikibot for various things. I want to know how I would, for example, replace:

ab

with

a

b

The problem is that I don't know what denotes a carriage return when using the windows command prompt. thanks Martin 17:30, 10 November 2005 (UTC)

That depends of the program, not the command prompt. \n is somehow an unofficial standard for "new line", so you could start trying that one :) ieffKieff 18:28, 10 November 2005 (UTC)
no joy, I'll use a bit of template substitution to solve my problem for now. thanks Martin 19:31, 10 November 2005 (UTC)
In Windows, newlines are CR and LF, so you could try "\n\r". I don't know if you can do this in regexes though. Dysprosia 02:21, 11 November 2005 (UTC)
Well, you can do it in regexes in all the languages I've come across (I was using it in JavaScript just this afternoon!) but that's not what was asked. The Windows command prompt (which, assuming you're using Windows 2000 or later is cmd.exe) is not exactly the most fully featured shell, so I'm not sure if there is a way of inputting non-printable characters (such as the binary 13 often represented as "\n"), or multiline strings (e.g. by only closing a set of quotes after all lines are done). Your best bet would be to work inside the more flexible environment of Python itself. - IMSoP 02:46, 11 November 2005 (UTC)
How else are you going to do a “replace” without a regex ? (unless you are not using a scripting language) Dysprosia 23:51, 14 November 2005 (UTC)
Please note that '\n' (newline) is ascii 10, not 13. ascii 13 is '\r' (carriage return). On windows, a line break is defined as both of them together: '\r\n'. I agree that working from python will be a better bet than from cmd. Also note that you can use os.linesep to tell you what should terminate a line on the current platform. There ARE versions of sed available for windows, though. I have used one called ssed.

[edit] Content Development

Need definition for Content Development --Lisastewart 17:58, 10 November 2005 (UTC)

Uh… The development (creation) of content, I guess. What context is this in? Garrett Albright 07:01, 11 November 2005 (UTC)

[edit] Lexers versus Parsers

In computer science, what's the difference between a lexer and a parser? They both seem to be involved in early stages of a compiler, where you separate textual input into logical units by known rules. But neither article links clearly to the other or explains the difference. Is a parser the first stage of a lexer? -- Creidieki 18:26, 10 November 2005 (UTC)

Being extremely general, a lexer converts text to tokens. A parser converts tokens to meaninful code. When you get an error in a lexer, it is because something is vague (such as: print print - is the second print a string or a function?). When you get an error in a parser, it is due to vague (or incorrect) usage (such as: print print - do you want to print the word print or print the output of the print function?)
I'm sure you'll get a dozen highly specific examples that conflict with this over-generalization. --Kainaw (talk) 18:50, 10 November 2005 (UTC)
The biggest difference, as far as I know, is that a lexer parses a stream of characters into a flat stream of tokens; parsers produce a hierarchical data structure (either implicit or explicit). For example, take the expression: foo+bar*baz. A lexer for a typical programming language would convert this into a stream of tokens such as:
ID(foo), OP(+), ID(bar), OP(*), ID(baz), END-OF-INPUT
Here, ID stands for identifier and OP stands for operator. A parser would then use grammar rules to reduce this to a more structured representation:
ID(foo) OP(+) ID(bar) OP(*) ID(baz)
is transformed to:
                OP(*)
                 / \
ID(foo) OP(+)   /   \
               /     \
          ID(bar)   ID(baz)
followed by:
            OP(+)
             / \
            /   \
           /     \
        ID(foo)  OP(*)
                 / \
                /   \
               /     \
          ID(bar)   ID(baz)
(Specifically, this is how a bottom-up parser works, but it demonstrated the principle better IMHO). Apologies for the cruddy diagrams—was my explanation helpful at all? —David Wahler (talk) 20:05, 10 November 2005 (UTC)
Yeah, that this was really helpful. Hopefully after the GRE on Saturday I can contribute some of this studying back to Wikipedia. I assume that the "more structured representation" is a tree structure in memory, perhaps the parse tree? (I asked a followup question below about trying to keep all of these data structures straight.). -- Creidieki 21:40, 10 November 2005 (UTC)

[edit] Finding two unknowns

It has been too many years since I've had any math, so I can't remember what this type of problem is called or what the preferred way of solving it is. It is very easy to solve with a simple program - but I think there is a standard math solution. Given a two-variable formula: Ax+Bxy+Cy=D, solve for values of x and y. Example: 7x+10xy+3y=83, x=2, y=3. I did a search for "two unknowns" and couldn't find examples with an "xy" term. --Kainaw (talk) 18:44, 10 November 2005 (UTC)

Given a single equation with two unknowns, there are, in general, an infinite number of solutions, with one unknown able to be expressed in terms of the other (given 7x + 10xy + 3y = 83, we get y = \begin{matrix}\frac{83-7x}{10x+3}\end{matrix}, and y has a real value for all values of x\ne -0.3 (for example, letting x = 42, we get y=-\begin{matrix}\frac{221}{423}\end{matrix}) and similarly values of x can be found for all values of y\ne -0.7.) With two unknowns, you need two equations for a unique solution; more generally, with n unknowns, you need n simultaneous equations to find a unique solution. AJR | Talk 19:17, 10 November 2005 (UTC)
as mentioned above, there is an uncountably infinite number of solutions to most equations with two variables. You might like to know how to graph the solution set. Since your equation has a quadratic term (Bxy), it will be a conic section, and hopefully that article has instructions on how to graph (your particular equation will be a hyperbola). If you're looking for integer solutions like the sample solution point you gave, then check out diophantine equation for more information (in particular, try Pell's equation, which I believe your equation can be reduced to). -Lethe | Talk 19:46, 10 November 2005 (UTC)
Nonlinear programming? Dysprosia 02:18, 11 November 2005 (UTC)

By the way, the "xy" term rotates the graph. You may want to see discriminant, as well. -- Natalinasmpf 01:22, 16 November 2005 (UTC)

[edit] Mathematics Algebra

Please can you solve this (a+b)³ Thank you.

I normally just respond: do you own homework.
Since I just asked a math question, I'll help:
This is (a+b)(a+b)(a+b). If you just do the first two, you get (a+b)(a+b)=aa+ab+ab+bb (look up FOIL method). That reduces to aa+2ab+bb.
Now, you have (aa+2ab+bb)(a+b) = aaa+aab+2aab+2abb+bba+bbb --Kainaw (talk) 19:39, 10 November 2005 (UTC)
Which is a³ + 3a² + 3a + 3b + 3b² + b³, which is a³ + 3a²b + 3ab² + b³. Notice the 1 - 3 - 3 - 1. For a higher exponent you go down Pascal's triangle to get the right numbers to multiply with. See that article for a further explanation. However, they seem to have messed up the exponents. I'll ask at the talk page there. DirkvdM 10:21, 11 November 2005 (UTC)
Just a simple case of the binomial expansion.--Fangz 17:03, 11 November 2005 (UTC)
What's the general way to expand something like (a+b+c+d+e+f+g+h+.....z)^n, given that z and n can be of any defined quantity? -- Natalinasmpf 01:24, 16 November 2005 (UTC)
Check out our article on the Multinomial theorem -Fangz

[edit] Rocket

How does a rocket Go into space? How does it launch? Thank you

  • Solid fuel, escape velocity, balance of kinetic and gravitational potential--Reference(www.com) 20:35, 10 November 2005 (UTC)
We have a rocket article. Garrett Albright 06:53, 11 November 2005 (UTC)
Hint. It brings its own fuel and oxigen, and pushes off of it. Did I give it away? --Artoftransformation 06:10, 14 November 2005 (UTC)

[edit] Flies

Why are flies dangerous insects?

Because some of them, e.g. the Tsetse Fly and the Black Fly, transmit disease. —Charles P. (Mirv) 21:27, 10 November 2005 (UTC)
and then there is the story that (some) flies move freely between shit and food, thus potentially spreading diseaes from the one to the other. Sounds yucky, but has anyone ever actually gotten sick from this? Can that be determined in the first place? DirkvdM 10:49, 11 November 2005 (UTC)
Also, flies have a rather 'interesting' way of eating, where they dissolve food before eating it by vomiting on the food to liqify it. User:SmurrayinchesterTalk 11:58, 11 November 2005 (UTC)
But that's strictly yuck, not a likely cause for the spreading of disease, because it would have to be a disease that lives in both flies and humans (assuming we're talking about danger to humans, which is homocentric). And that's rare (the only example I can think of is malaria). But if flies move between human shit (or mamal shit) and human food there is a potential problem. Often mentioned, but is there any evidence? DirkvdM 10:34, 12 November 2005 (UTC)

[edit] Blocking a browser from accessing a specific URL

How would I go about doing that, for instance, some setting to block/redirect away from a specific set of URLS, for instance, if someone tries to load www.google.es, having it automatically redirect to www.google.com, or mabe just block it in definatly--Reference(www.com) 20:45, 10 November 2005 (UTC)

Are you using Windows? If so what version?
Under Windows you can use the HOSTS file. FInd it under
  • Windows XP = C:\WINDOWS\SYSTEM32\DRIVERS\ETC
  • Windows 2K = C:\WINNT\SYSTEM32\DRIVERS\ETC
  • Win 98/ME = C:\WINDOWS
If it doesn't yetb exist on your system, create it, in the folder it should be in.
To this file, you can add lines such as this:
127.0.0.1 www.adserv.com
which will redirect any attempt to access www.adserv.com to your local IP 127.0.01 (your own machine. Just substitute the URL with the link you want to block, and the IP with the IP of the page you want it to redirect to. Done.
Now, whenever your machine tries to access your banned url, it will check the HOSTS file, find the 'corrected' IP, and will connect to the 'corrected' page.-- Ec5618 20:58, 10 November 2005 (UTC)
Thanks, that seems like it would do the trick--Reference(www.com) 21:04, 10 November 2005 (UTC)
Would you happen to know the ip for google or yahoo, just off the top of your head?--Reference(www.com) 21:14, 10 November 2005 (UTC)
  • Very odd, it blocks some websites, but not others..
For instance: as a test:
127.0.0.1 google.com <--blocks the google domain name
where as
127.0.0.1 yahoo.com <--does nothing
Am I messing up the formating somehow, or is it something else?--Reference(www.com) 21:21, 10 November 2005 (UTC)
For the hosts file, yahoo.com is not the same as www.yahoo.com, my.yahoo.com, etc. It will only match exact hostnames, so you need to add all of those to completely block Yahoo.
Note that even in this case, it's possible to circumvent this by using the IP address, at least for sites that are not on shared hosting. --Pidgeot (t) (c) (e) 22:48, 10 November 2005 (UTC)


Can you use wildcards for URLs in the HOSTs file? Or is there any other way to do similar? --Chaosfeary 11:10, 11 November 2005 (UTC)
The HOSTS file cannot use wildcards. The closest thing would be to write a small program to monitor browser instances and manipulate them if a forbidden URL is accessed (although you'd also need to check IPs, or you'd still be able to circumvent it). --Pidgeot (t) (c) (e) 16:47, 11 November 2005 (UTC)
Alternatively, you could use a "net-nanny" type of software.
Regarding Reference's earlier question concerning the IP addresses of Google and Yahoo, they tend to have more than one, or shared hosting as Pidgeot correctly mentioned. Try performing an nslookup on google.com and yahoo.com through the command line. (nslookup google.com) This should give you their IPs, but nslookup is a bit of a dodgy DNS tool, so don't trust the results too much. -- Daverocks 11:21, 11 November 2005 (UTC)

[edit] Data structures used by a parser

I'm having a lot of trouble telling from the various articles what the different data structures used by a parser are for. There seems to be a parse tree, a parse table, an attribute grammar, an abstract syntax tree, a symbol table, and possibly a semantic stack. The articles on these are kind of low on context. Which of these are features of the language, and which are different for each program parsed? What do they do? Which one is the output from the parser into the ... ummm... into the compiler? -- Creidieki 21:37, 10 November 2005 (UTC)

  • A parse tree is basically the diagram I showed above. It's a tree representing the program in which each leaf node is a terminal, and all other nodes are nonterminals. Its distinctive feature is that it corresponds exactly to the grammar.
  • A parse table is a fixed structure that acts as a decision table for a bottom-up parser. It's the same for every program in a given language, and consists of rules like "if the parser is in state 4 and the next input token is an identifier, read it onto the stack". Usually these are automatically generated; for example, the yacc parser generator takes a set of grammar rules as input and produces a parse table and the code to process it as output.
  • An AST is similar to a parse tree except it doesn't exactly correspond to the same sequence of tokens as the input program; it has a simpler representation that still has the same semantics as the input program. One explanation I found is here.
  • A symbol table generally isn't used until after parsing; it holds the addresses and metadata about any identifiers (such as variables) that may be referenced by the code.
I'm not sure what an attribute grammar or semantic stack are. As I understand it, the parser produces a parse tree, which is then refined into an AST and sent to the compiler proper. The compiler then performs things like dataflow analysis and generates the code. —David Wahler (talk) 04:39, 11 November 2005 (UTC)

[edit] Special Relativity: Thought experiment

I came up with a simple experiment the other day I couldn't give a satisfactory solution for. It's the following:

- Imagine that instead of a sun we have a giant screen with an Ed Wood movie being projected on. Because I hate the movie, I decide to take my brand-new spaceship and fly away at c (hypothetically) to deep space in the opposing direction of the light coming from the screen to the Earth. The question is: When I'm still accelerating, say at 0,5c, I should see the movie slowing down (in my reference frame) and in the hypothetical arrival to c, the movie should stop due to time dilation. Can anyone explain me what do the photons do exactly here? Is it something like the photon from the screen chases me but not fast enough to catch me in finite time? Wouldn't this be in contradiction with the universal constancy of c?

--GTubio 22:15, 10 November 2005 (UTC)

the movie slows down, but that means that the screen has more time in between frames. It doesn't mean the photons emitted with each frame travel more slowly. The photons still travel at c. -Lethe | Talk 00:04, 11 November 2005 (UTC)
Okay, you have saved me from at least two days of headaches. Thank you very much.

--GTubio 02:10, 11 November 2005 (UTC)

And the film severly red-shifts, so you will need a special device of some kind to convert the red-shifted light to something visible.
Which, in the case of Ed Wood films, is a marked improvement :) --80.65.195.132 15:29, 18 November 2005 (UTC)

[edit] DNA staining

It's probably just me being paranoid, but I'd rather put my mind to rest. A few weeks ago my class in Biology did a experiment where we extracted DNA from onion cells into test tubes, and then stained the DNA so that it would show up in the test tube. I'm not sure if we were supposed to add the stain ourselves or if the teacher was supposed to do it, but either way I added the DNA stain myself and got a little on my fingers. And at the time I thought it might be a tad dangerous - anything that stains an onion's DNA could affect mine (possibly?) - and it stained my fingers, but I washed most of it off and it disappeared soon enough, so I didn't think about it. But just now I've heard from a friend who did a different experiment, also using a DNA stain, and they were told not to get any on their skin or it could mess up their DNA. Which led me to worry. It probably doesn't help that I don't know which particular stains I used or they used, but I seem to recall it being blue. So am I in mortal danger, or is it nothing? I mean, the school wouldn't let us use something extremely dangerous, would they? --Sum0 22:37, 10 November 2005 (UTC)

  • I'm reasonably sure that the stain doesn't do anything to the DNA per se. If I recall, stains are molecules where half is a binding protein of some sort, and the other half is responsible for the color. They just bind to different sorts of proteins, I believe. I doubt they will have any interactions with your DNA, which are probably still quite safe in their little nuclei (you are probably only binding the stain to the ourside of your cell walls at worst when it sticks to your hands, though I'm neither a chemist nor a biologist). I also think it is safe to assume that if getting a small amount of stain on your fingers was toxic, you'd have been required to wear gloves. Given the likelihood of getting stain on your fingers, you'd probably have heard of a rash of biology-related high school deaths if it was the case otherwise. --Fastfission 00:48, 11 November 2005 (UTC)
To an extent it depends on the stain used. As Fastfission says, if it was something really nasty you would have been instructed to wear gloves (if at university or college) or not allowed to touch it at all (if in high school). Some DNA stains are potentially carcinogenic; they are capable of penetrating live cells, and when they stick to DNA they can interfere with its proper replication. Of course, since you were staining DNA that was extracted from cells, it's quite likely that a stain was chosen that doesn't readily penetrate the membranes of live cells. (No membrane penetration means no way to get to the nucleus, and no way to damage the DNA of your living cells.) You can ask your teacher/professor what the stain was—I'd guess something like methylene blue or Nile blue (both are relatively nontoxic). Your skin also provides a pretty good short-term barrier to many (but not all) chemical compounds; washing the stuff off quickly probably limited your exposure.
In practice, there's way too much paranoia about carcinogenic chemicals. It's good to minimize your exposure to the nasty stuff, but odds are being exposed to a little bit won't do you any lasting harm. Just try not to do it again—if nothing else, your significant other might be a bit freaked out if you have blue fingers. TenOfAllTrades(talk) 02:37, 11 November 2005 (UTC)
If it was a blue stain, it was probably methylene blue - a lot of schools use it; if you visualized the DNA with an ultraviolet light and were told to be careful about getting it on your hands, it was probably ethidium bromide. Ethidium bromide is a mutagen, which is why you shouldn't make a habit of getting it on your skin, but one exposure isn't going to make a lot of difference. It sounds like you were working with methylene blue, and that your friend used ethidium bromide. - Nunh-huh 07:07, 11 November 2005 (UTC)
Thanks for the answers. From the sounds of it, it was probably methylene blue, so nothing to worry about. Once again, thanks! Sum0 18:56, 11 November 2005 (UTC)


Just a note: you've probably just done more damage to your DNA in your cells in sixty seconds of cellular respiration due to mutations and free radicals produced during metabolism than foreign DNA could ever do (the only time it will be destructive is when it uses some sort of vector like a virus....welcome to aging! After a while (decades, to be exact), this damage might result in cancer! :D So no real harm done by foreign DNA you handle, really, unless that foreign DNA is a virus. -- Natalinasmpf 01:31, 16 November 2005 (UTC)

[edit] November 11

[edit] Does the study of an object change the nature of an object?

I seem to remeber hearing that, in relation to the study of atoms, a scientist will often change the very nature of an object that he studies just from observing the object. Is this a real principle?

Sounds like you're talking about the Heisenberg uncertainty principle. --Quasipalm 02:04, 11 November 2005 (UTC)
It does indeed - but the original statement does not sound precise enough. In a hand-waving explanation, the uncertainty principle is sort of a neat way to say that in the quantum world, there are certain things that you can't measure to an arbitrary precision simultaneously. --HappyCamper 03:10, 11 November 2005 (UTC)
More specifically, you can't measure both the speed and position; you'll have to choose which of the two you want to measure. On a more philosophical level, observation is not completely passive. There has to be some interaction. When you watch something, you need it to reflect light. This interaction with light is no problem for most of the observations you want to do. But when the object is subatomic, a single photon (or what ever interacts with it to do the observation) constitutes a considerable amount of energy, which may affect the object to the point that the observation becomes meaningless. I'm no physicist; did I put this the right way? DirkvdM 11:46, 11 November 2005 (UTC)
The Heineken Uncertainty Principle: "It's impossible both to consume a large quantity of alcohol and subsequently to be able to accurately describe said quantity of alcohol, to the police officer who has pulled you over." StuRat 19:39, 11 November 2005 (UTC)

This is also closely related to the measurement problem. - Cobra Ky (talk, contribs) 19:46, 11 November 2005 (UTC)

[edit] Runge-Kutta and Matlab

Hi,

The following is a relatively involved problem, and IS for a homework assignment. I know wikipedia has a policy against 'doing homework' for someone, but I'm looking more for guidance / an overall idea of what needs to be done in the problem below:

A short PDF describing the paticular ODE is here:

http://www.srl.gatech.edu/education/ME2016/Fa05/Homework/ME2016.HW7.F05.pdf

What is the overall procedure I need to take to solve this?

Well for starters, I think the assignment is very clear and organized. You need to read through it at least once and while you're at it, do the first problem right away. What you need to do, is to figure out what the set of 4th order Runge-Kutta equations are, and how you calculate the error at each iterative step. These should be outlined in your notes or your text. If not, well, our article has some of the solutions already :-) --HappyCamper 03:04, 11 November 2005 (UTC)
From the assignment:

We would like to re-emphasize the policy on collaboration. Collaboration is encouraged. Discussing the assignments with your peers will help you to develop a deeper understanding of the material.

I would take this on as a devide and conqure type assignment. Take a laptop to the library, and reserve a study room. Have at least 6~12 of the students in the class, with text books and manuals. The excerise is NOT the solution to the problem. The EXCERCISE is how to apply collobration to assignments. I would doubt that any one person in the class can do this alone. Hurry, the deadline is TODAY.
Let say that a predomanant number of students fail at this assignment. What did you learn about what you should have done, and what can you do about this situation later? What can you learn from those who were sucessfull? Can you interview each one?

"We wish to foster the development of methods of teaching and learning about the product realization process which are in keeping with principles embodied in TQM/CQI and Decision-Based Design."

The solution to the problem: Gather as many of your peers as possible to breakdown the problem into as fine-grained tasks as possible, using partnership and communication. Manage it collectively, rotating study, creation, testing, and leadership. Sounds like a WikiPorject to me!
--Artoftransformation 05:24, 12 November 2005 (UTC)

[edit] Where is the world's largest sea?

Dear sir, I am trying to find out which is the biggest sea in the world. I have searched the website and found two answers ----the South China Sea(in Wikipedia English Version) and the Coral Sea(in Wikipedia Chinese Version).I am confused and wish to know the exact answer. Can anyone help me? Thank you so much.--03:12, 11 November 2005 (UTC)

It's the Coral Sea near the Australia. It is 4.800.000 sq.km

That depends on how you define the sea and what constitutes a sea (as opposed to an ovean) in the first place. The Mediterranean Sea is well defined because the Strait of Gibraltar is so narrow, but where would you put the border between the Coral Sea and the Tasman Sea? (And why are they separate seas in the first place?) That's pretty arbitrary and I suppose that's the reason figures on the size of a sea may differ. DirkvdM 11:58, 11 November 2005 (UTC)

[edit] Why it's good to look at distant object with tired eyes?

when your eyes feel tired from looking at close object, it is good idea to look at distant object for a few minutes.Why do you think this would help?

It's because the natural rest position for your eyes is to face roughly forward, equivalent to looking far away. Although you don't realize it normally, pointing your eyes at closer objects requires you to contract the muscles that move your eyes. When your eyes are "tired" it's really these muscles that are tired, so looking far away lets you rest them. -- SCZenz 03:26, 11 November 2005 (UTC)

Thank you for your answer!

[edit] What is the difference between film of camera and retina of the eye?

I am doing my science project.If you can please help!

Compare and contrast the image that is formed on the film of a camera and the ritina of the eye.(chart and point form)

Please refer to the top of the page, where it says
Do your own homework - if you need help with a specific part or concept of your homework, feel free to ask, but please do not post entire homework questions and expect us to give you the answers.
To get you started, however, we have excellent articles with lots of diagrams and information on the human eye and its retina, as well as the structure and function of a camera. TenOfAllTrades(talk) 06:46, 11 November 2005 (UTC)

Think about how the camera records visual information and how the eye records visual information. While both use a lens...the eye uses the optic nerve and sends the information to be travelled to the brain (where it will probably last till your death if you take time to remember it)......whereas film might degrade. -- Natalinasmpf 01:35, 16 November 2005 (UTC)

[edit] Chemistry

Which is the most oxide acid ever noticed?

I am not sure I understand the question. Is it the acid with the most oxygen atoms in its molecule?

Or the acid which oxygen contributes most to its acidity?

Maybe oxide=oxidation in the question? --Commander Keane 18:48, 11 November 2005 (UTC)

I mean which acid is the most powerful ever noticed.

See superacid. Alphax τεχ 03:49, 12 November 2005 (UTC)

[edit] Sewer parasites

Sometimes i see some parasites inside a sewer at my school.Where are they from and why are they there? Why 3 posts are created? I created only one.

You must have accidently hit 'Save Page' several times. Could you describe the parasites? User:Smurrayinchester16:35, 11 November 2005 (UTC)
Also, what are they parasites on? Parasites are usually found living on, or inside, another living thing. Notinasnaid 19:10, 11 November 2005 (UTC)

[edit] Water evaporation rate vs. Temperature

Assuming air flow rate and atmospheric pressure remian constant, what is the relationship between temperature and evaporation rate of water? Are there any graphs or tables that would provide this information? JTA

[edit] Thorium as a nuclear fuel

What are the advantages of a thorium fuel cycle, as mentioned in passing at Nuclear fuel cycle? ‣ᓛᖁ♀ᑐ 17:09, 11 November 2005 (UTC)

The article gives the fact that thorium is more abundant than uranium as a reason. --R.Koot 17:15, 11 November 2005 (UTC)
Nonproliferation. As it is, a civil nuclear power program is a handy precursor to building nuclear weapons. Thorium reactors, however, aren't nearly as bad - they produce U-233, which can be weaponised, but it's certainly not easy. Thorium has a few incidental comments on the pros and cons. Shimgray | talk | 19:05, 11 November 2005 (UTC)
However, to make use of a thorium fuel cycle you need an amount (relatively small, but some) pretty highly enriched uranium, in the order of 20%. I'm not qualified to do the calculation as to whether you can make a bomb out of that, but it's a lot more potent than the LEU used in conventional reactors. --Robert Merkel 00:05, 13 November 2005 (UTC)

[edit] Adobe Acrobat question

I'm just wondering if there's a way to do something in Acrobat. Let's say I have a PDF with, say, six pages: ABCDEF. Is there a practical way to turn it into AABBCCDDEEFF? By "practical", I mean, "other than doing it one page at a time". I'm interested in doing this to a document with about 150 pages, so the ability to scale it up is important. I couldn't figure out an obvious way to do this but it doesn't mean that it can't be done, of course. (The reason, by the way, is that the pages are scanned in as two to a page, horizontally. This is fine for printing, but for reading on the computer it is difficult. My theory was that if I could duplicate each page, I could then crop the even-only pages and odd-only pages so that they were left and right pages respectively, and make it so that each PDF page corresponded to only one page of the document, rather than two. If there's another way to accomplish this, I'm all ears.) --Fastfission 19:19, 11 November 2005 (UTC)

I can't quite get it to work right, but I suspect one way involves checking "Print to File" and printing two copies without collating. After doing the Print to File bit, you might have to follow the second part of the directions here. Hope that helps a little. AySz88^-^ 19:59, 11 November 2005 (UTC)
There may be a trick in printing two copies, non-collatated, to another PDF. ( see previpus refrence), but you mught also be able to script the printing and naming of the pages with apple script, then duplicate them, and have one set cropped by photoshop, only the right hand side removed, and the second set, the left hand removed, and gather them into one PDF.
How much does the book cost?
I thought about opening it as a plain text file (not in acrobat reader), after which it should be easy. But when I do that with a pdf file I don't get to see the text. I don't know why this is, but it's another reason for me to dislike pdf files. They're very difficult to manipulate. DirkvdM 11:03, 12 November 2005 (UTC)
I'm pretty sure you can open a PDF as a text file provided it is not compressed. Compressing is often the default setting so you need to uncheck the option before saving. Shantavira 18:43, 12 November 2005 (UTC)
You can open a PDF file as text and you will see the structure of the objects making up the PDF file. But it isn't a text file that you can just hack around. Any change will break the file unless you follow the rules in the 1200 page PDF Reference. Notinasnaid 19:19, 12 November 2005 (UTC)
Opening it as a text file won't work at all in this instance -- the PDF in question is a collection of page images, scanned in from originals. I'll try something along the lines of print-to-file and see if I can get it to work one way or another, that's a good suggestion. Exporting to Photoshop is of course an option but is always in my experience a sure-fire way to increase the size of the final PDF by about 1000%. --Fastfission 01:48, 14 November 2005 (UTC)

[edit] Hurricane Rita

I am looking for the square mileage of the area damaged by Rita upon landfall on September 24th.

Have you read our article on Hurricane Rita? Alphax τεχ 03:56, 12 November 2005 (UTC)

[edit] Abilities and limitations of computers

I'm looking for list of general computer's abilities and limitations (what computers can/can't do)

The absolute only thing that a computer can do is compute. Anything you think a computer is doing is nothing more than a series of mathematical computations. --Kainaw (talk) 02:01, 12 November 2005 (UTC)
The question is just general and vague. You don't even specify what you're using as a baseline. Are you taking into account something like the IBM Blue Gene computer? Or are you talking about common off the shelf computers with one or two processors? Or four processors if you include the new Mac Power Mac G5s. Dismas|(talk) 02:19, 12 November 2005 (UTC)
NPOV! The new Apple Computer PowerMacintosh G5 comptuers, have 2 processors, of which each processors, have dual cores. Giving you 4 cores on 2 processor dies. This is distinctly diffrent from the Quad Processor Daystar Genesis Machines, or off the shelf Quad Xeon Machines.
Computers are the ultimate computational happy puppie. They will run an infinite loop, until they are unplugged. [www.cs.bu.edu/~gacs/papers/tudosklub.pdf| The theory of computation ] They cannot be programmed to do things that are outside of computibility. [Turing_Machine] They are still dumber than houseplants. If you water a house plant, and give it light, it has sence enough to grow towards the light. ( there are even rumors about the secret life of plants ). Computers cannot think. They may, because of the very large amount of interdependant components exibit chaotic behavour. Chaos_Theory. Compters like beasts abstractith not. They can beat humans at chess. [GNU Chess],[Zappa_%28ChessEngine%29],[30]. Some proofs of Mathematical theroms can be done only on compters. Proof and beauty

You may find more. --Artoftransformation 05:03, 12 November 2005 (UTC)

At a more elementary level, computers are about information, which they can store and manipulate (everything they do can be reduced to these two main functions). The manipulation can be regarded as computing (as suggested by the name 'computer'), but another term for it would be logical manipulation (mathematics and logic are two forms of the same thing). In 'normal' computers, the information is stored in a digital way - 0/1, on/off - implemented by letting a current flow in one of two directions (in analogue computers, however, the most elementary bit of information can have any number of values). The manipulation is done by the cpu, which can either shift the bits in a byte left or right or add bit/bytes together or negate them. These last two are the only two manipulations needed to do any calculation. Any at all (which can be logically proven). DirkvdM 11:15, 12 November 2005 (UTC)
Thank you. Excellent answer also. --Artoftransformation 17:28, 13 November 2005 (UTC)
In a mathematical sense, classical computers can't *ever* solve undecidable problems, and some problems are known to be so hard that no conventional computer can solve them in a reasonable (and by reasonable I mean "before the Sun turns into a red giant and wipes us out) amount of time. See Halting problem for an example of a famous undecidable problem, computational complexity theory for a discussion of problems which can be solved, but so slowly not to be useful. A good example of an intractable problem is figuring out the absolute best possible chess move from a given position; the only way to determine the ultimate chess move is by exploring every possible sequence of moves, and there are so many it's simply not possible to do so in most positions. Another famous one is the travelling salesman problem, which says "given a set of cities which a salesman must visit, what's the quickest way for the salesman to visit every city and return to his home?". Complexity classes P and NP discusses the most famous unsolved problem in computer science - while we *suspect* that there is absolutely no way to solve the travelling salesman problem efficiently, we have not been able to show this for certain, despite 30 years of trying. Be warned, a lot of the discussion in the linked articles is quite mathematical. --Robert Merkel 00:02, 13 November 2005 (UTC)
Thank you. Excellent answer also. --Artoftransformation 17:28, 13 November 2005 (UTC)
You really try to be everyone's friend, don't you? :) DirkvdM 09:38, 14 November 2005 (UTC)

[edit] November 12

[edit] Thrombin - which reaction is favoured in the coagulation cascade and why?

I am learning about the blood coagulation cascade. While I understand that Thrombin catalyses more than one reaction, I believe that the most important of these is catalyzing fibrinogen to fibrin, so that stable clots can be formed. What I don't understand is, if the thrombin is available for previous reactions in the coagulation cascade, such as the conformation of factor VIII to factor VIIIa, then why isn't it possible to skip the all the previous steps of the cascade, moving directly to the formation of fibrin? Why are the previous steps necessary?

- Claire

[edit] Instant Messages

User asked the following question on our Help List.

Hi, I'm adding an user to Simple Instant Messanger list and I'm connected thru ICQ. Is that user can see after it that he is added by me or not? Or can I be asked for authorization request?

Thanks in advance, I.

Capitalistroadster 10:05, 12 November 2005 (UTC)

[edit] can you judge the speed of your own farts?

Do they have to be your own? And is this meant as a serious question? Ah, well, even it is not, it's an interresting bit of trivia. I'll take 'judge' to mean 'measure'. An anemometer would need some time to get up to speed and farts probably don't last long enough for that. Also, a fart is a narrow jet of air, and I don't think anemometers would be able to handle that (unless they're very small perhaps, which might also deal with the first problem). However, pressure anemometers probably don't have the first problem and a tube anemometer might not have the second problem either. But the thought of inserting a tube in my arse makes my cheeks somewhat anemic (now that's a rather lousy word joke even by my standards - and don't make jokes about which cheeks I mean, please). DirkvdM 11:48, 12 November 2005 (UTC)

If you are planing to make a living out of your high speed farts you may be intereseted to know that we have an article on professional farters. Bizarre!--Goshawk 12:08, 12 November 2005 (UTC)
While an anemometer needs a "gust" of at least 3 seconds to get a reading (too much for a human I'd guess) you could use a hot-wire anemometer which only needs a short (milliseconds) gust - perfect for your purpose. The heat of the fart may need to be taken into account as it may alter the reading (giving you a lower than expected speed). So yes, you can judge the speed of your own fart.--Commander Keane 17:31, 12 November 2005 (UTC)
I would be 'concerned' that the fart would not be uniform, laminar gas flow. That is, the gas coming out would be turbulent, so you're going to have eddies and vortices—you'd probably want to take a lot of measurements to get an idea of an 'average' velocity. A measurement of the speed through a small volume could be very misleading. TenOfAllTrades(talk) 19:21, 12 November 2005 (UTC)
And of course, the velocity would vary significantly based on the abdominal pressure being exerted and the degree of sphincter constriction (like your breath velocity depends on your diaphragmatic compression and how open your lips are). alteripse 19:25, 12 November 2005 (UTC)
I don't think you have to worry about turbulence and abdominal pressure - it's up to the farter to produce the fastest, most efficent fart possible. This includes minimising turbulence to gain speed and having good control of their sphincter.--Commander Keane 16:19, 13 November 2005 (UTC)

Aren't you concerned that there might be a trade-off between speed and control? alteripse 16:29, 13 November 2005 (UTC)

Farts travel at the speed of sound....well mostly :-) --Eye 22:09, 13 November 2005 (UTC)

In my experience they travel at the speed of smell. Rob 13:43, 14 November 2005 (UTC)

[edit] Lift to space

A suggestion on QI last night, that I've once wondered about too. Considering that outer space is about 100 km up, wouldn't it be possible to build a ladder or lift that high, so we wouldn't need those expensive rockets? (A modern day tower of Babel.) Of course this would also cost a bit, but you'd only need to build it once. And working the lift would also cost energy, but I assume it would be much more efficient than a rocket, which probably spills most of its energy sideways. And the engine and fuel could remain on the ground in stead of having to be transported as well (I suppose this is the biggest advantage). Once there, a rocket would need only a fraction of the energy to get further out in space. If you go high enough, centrifugal forces of the rotating Earth might even be used, to the point that it actually generates power in stead of consuming it. This is getting to sound better and better as I write it. DirkvdM 15:40, 12 November 2005 (UTC)

You may be looking for the space elevator. AySz88^-^ 16:35, 12 November 2005 (UTC)
Absolutely brilliant! I should in the future look a bit harder before I ask, because Wikipedia seems to have an article on just about anything and it makes sense that this has been thought of before. Of course the cable design makes most sense. The estimated cost of 40 billion USD seems peanuts if you consider that Amsterdam spent billions on a metro line just to cut a corner. If this were a worldwide project, the cost per participating country would be relatively minor. I now realise that the use of centrifugal force can't work because once that effect sets in, the cable would start to drag and possibly even wrap itself around the Earth (?). But what if it were a rigid structure? DirkvdM 10:14, 13 November 2005 (UTC)

[edit] Menthol and the voice

My friend's voice teacher told him that cough drops that have menthol in them harm the voice for singing. Is this true? If so, is there any substitute that would work just as well? Hermione1980 18:31, 12 November 2005 (UTC)

This page is the closest I could find to an authoritative note on the topic, for what it's worth. A Google search reveled that it's a common belief, though there are scads of silly myths among singers. If it's a real concern, I'd just call a local laryngologist. George 09:49, 14 November 2005 (UTC)

[edit] A propos hydrocarbons

Ok, what I meant in my previous question was, why are hydrocarbons, carbon and hydrogen the primary sources of energy through combustion? Why not silicone, boron, or anything else?

Combustible organic molecules–quite literally–grow on trees. You can drill a hole in the ground and get barrels of the stuff, too. Yeast will turn plant sugars into alcohol. Organic fuels have been around for millennia; we have a lot of experience with them, they occur naturally, and they're quite abundant.
There aren't pools of silicon or boron compounds lying around waiting to be burnt. Silicon, for instance, is mostly locked up as very stable and very unreactive silicates; there isn't any easy way to use them as a fuel. The same applies to boron, with the added problem that the abundance of boron compounds is lower. TenOfAllTrades(talk) 19:27, 12 November 2005 (UTC)
So why not burn sugar, since it's also compromised of hydrogen and carbon, like alcohols, hydrocarbons, etc?
There are several reasons. Since sugars are solid you can't pump or pour them, consequently they are more difficult to handle. They're bigger molecules, so they're harder to combust fully&nmdash;incomplete combustion leads to soot and bad smells. Also, sugar has to come from somewhere. Usually it's extracted from plants; this takes up a large amount of agricultural space.
So—sugar isn't used directly in transportation because of handling problems, and it's not used in power plants because of cost and supply issues.
Interestingly, Brazil ferments sugar to produce large quantities of ethanol. By growing sugar cane in their own country and making their own ethanol fuel, their transportation sector is sheltered from major price swings in the cost of imported oil. TenOfAllTrades(talk) 19:45, 12 November 2005 (UTC)
Ive heard that elephant grass is an excellent energy source? What's in elephant grass that gives it such a high energy content? I also feel that the defunct coal sector can really be revitalised to refine perfect quality gasoline at lower prices (c. 700$ vs 1100$/ton, presumably) compared to petroleum)- wonder why so little interest in this subject?
and b) What does energy content mean anyway? How much steam/heat a compund gives off when combusted? How long it can combust? Thanks!
The energy content is, for these purposes, the energy you could extract from the compound. So, yes, the heat (or energy) given off when burnt would be a good measure for the energy content of petrol or ethanol in this case. In the case of uranuim, it would be the energy you could extract through nuclear fusion.
I don't know why elephant grass in particular would have high energy content. Maybe lots of sugars in the grass, which could be turned into high quantities of ethanol? — Asbestos | Talk (RFC) 20:58, 12 November 2005 (UTC)
The elephant grass is burned, no fermentation involved?
Aluminium is a very good fuel. It's mostly used in rocket engines; see solid propellant. There was also some guy who proposed burning aluminium wire to power cars, except he thought he was making a hydrogen fuel cell, powered by electrolysis of water, with the accumulation of aluminium oxide dust being a minor issue. ‣ᓛᖁ♀ᑐ 21:20, 12 November 2005 (UTC)
Apropos sugar. Suppose we made an engine that runs on sugar and rides a two-wheel contraption. Let's call the machine a human and the contraption a bicycle. Making the machine is called sex, which is fun, eating the sugar makes the machine happy, riding the contraption keeps it fit and the lack of exhaust fumes keeps everyone healthier. Actually, this is such a good idea that I've been doing it all my life. And it saves me bucketloads of money too. :) DirkvdM 10:25, 13 November 2005 (UTC)
A lack of exhaust fumes? You're only fooling yourself, dude. Garrett Albright 14:40, 13 November 2005 (UTC)
Well, at least my exhaust fumes are lacking. That is, of this kind. :) DirkvdM 09:41, 14 November 2005 (UTC)

[edit] "The connection was refused when attempting to contact ..."

Hi - I'm using Firefox on a Win XP computer. I've been trying to read my web-based email from several different providers, but I always get "The connection was refused when attempting to contact ____ " e.g. "...to contact www.google.com" (for gmail) or "...to contact webmail.wesleyan.edu" or whatever. This happens, I believe, only for secure sites like email.

The same thing happens when using IE, only it doesn't give a message, it just shows an error page ("The page cannot be displayed").

This does not happen on another computer which is sharing the same router, so I don't think it's router firewalls or anything.

I've read some internet postings saying it might be Norton screwing me up. I don't think I've changed any settings, but it's possible someone else has. Lot's of messages have suggested uninstalling and reinstalling Norton, but I don't have the original disks anymore, so I'd prefer not to.

Any suggestions?

— Asbestos | Talk (RFC) 20:52, 12 November 2005 (UTC)

What else is running on your computer? A firewall of some sort? I've gotten that message before myself, and it was because of a firewall that I had set up incorrectly. --HappyCamper 02:02, 13 November 2005 (UTC)

[edit] Cannot create creator!

I'm perplexed, I recently reinstalled Easy CD Creator 5 Basic, and now I can't use the data CD option anymore, and I'm not sure what's going on..
I found lots of 3rd party sources via google, most of which recomended editing the registry to fix the problem, which I'm hesitant to do,
if anyone has another solution that would be much appreciated, thx--ineedhelp 23:24, 12 November 2005 (UTC)
I'm sorry that I can't help you directly on your problem, but that title looked like the best opportunity for a flame war I'd seen on the Reference Desk in ages - the cosmological argument and its inversion (that if a creator God was necessary to create the universe, then by the same reasoning something must have created God...). And all we got was a technical question about a CD burning program! ObAttemptToHelp: can't you back up the registry before you fiddle? --Robert Merkel 23:48, 12 November 2005 (UTC)
Well as helpful as that was, I'd rather not try and edit the registry at all, there must be an easier solution, since I never had to go through any of this the first time around (of course it came bundled/pre-installed), and yes, it is a funny name for an error message, but that kind of tangent isn't going to help me much--ineedhelp 00:02, 13 November 2005 (UTC)
This is on Roxio's own website. When you install and add patches, the registry keeps information. When you reinstall, the new install doesn't match up with the registry. So, they made a program called RoxioZap ([31] or [32]). This will completely erase all the Roxio stuff from the computer so you can start over with a fresh install. --Kainaw (talk) 00:12, 13 November 2005 (UTC)
Thank you... now feel free to turn this into a philosophical debate, if you want (-;--ineedhelp 00:16, 13 November 2005 (UTC)

[edit] November 13

[edit] electrical

electrical tester, that we use to see if current is there or not in sockets,...n when we use it even while standing on wooden stool the ckt gets completed n the bulb in tester glows how?? irrespective of the thickness of wooden stool(insulator)..how it happens??


from Avinash parhi,India

--59.93.129.191 02:33, 13 November 2005 (UTC)

Keep checking back for an answer while it is developed over the course of a few days, as we generally don't reply by e-mail. --HappyCamper 02:37, 13 November 2005 (UTC)
Ah, I'm not sure you've thought this out. Most likely, the tester is completing the circuit itself. I.E. it has a bulb in it and two contacts, allowing the electricity to pass through it, lighting the bulb. Superm401 | Talk 13:14, 13 November 2005 (UTC)
I would suggest that although a wooden stool acts as a resistor, nothing is a perfect insulator, and there is still sufficient current to light the bulb. I suspect inductance may play a part too. Shantavira 14:09, 13 November 2005 (UTC)
There are "hot-wire" testers which only require one contact with the ungrounded side of an AC mains source to indicate. The technology uses capacitance to ground (earth) and can be quite sensitive. --hydnjo talk 14:59, 13 November 2005 (UTC)

He doesn't quite say so, but I suspect he's talking about the simplest kind of electrical tester, which has two leads and a neon lamp inside, along with a big old (100k or so) series current-limiting resistor, since small neon lamps require a ridiculously small amount of current. Secondly, I suspect he's asking about the case where you connect one lead of the neon tester to a hot wire, and hold the other lead in your hand. In this case, the neon bulb will in fact glow -- not as brightly as when you connect that second lead to the neutral or ground wire, but still plenty bright enough for you to see. (And in fact this effect leads to a useful trick, one I use all the time: determining which of two indistinguishable wires is hot and which is neutral.) The current flow -- if indeed there is any -- is so tiny that you don't feel a thing.

The explanation for why/how this works always involves phrases like "the capacitance of your body", although this has never made perfect sense to me. Steve Summit (talk) 19:50, 20 November 2005 (UTC)

[edit] CPU vs RAM?

Is it strange that my CPU is maxing out at 100% when such a large fraction of my RAM remains unused? Causes? Fixes? Perfectly normal? Etc?--ineedhelp 02:39, 13 November 2005 (UTC)

A computer can carry out intensive processing without needing much RAM, so that is not strange at all. --Pidgeot (t) (c) (e) 02:48, 13 November 2005 (UTC)
That's not strange, RAM and CPU are different resources that are not necessarily related. Click the Processes tab to see what process is using up you CPU.

High CPU usage indicates your computer is carrying out a processor intensive task (of which there are many). Some of these required large amounts of RAM, and some do not. The two resources are orthogonal in that respect. So no, it's not surprising that your CPU is at 100% without a large consumption of RAM. Nor would it be surprising if there was a large consumption of RAM. →Raul654 07:30, 13 November 2005 (UTC)

OOP! It is not strange, but that is not was is alaming. What is running on 48 processes? Please click on the previous tab ( Processses ), and click on the CPU Column. That will sort processes by CPU usage, and tell us which one of the 48 processes is taking your CPU time.

( I am browsing, playing, downloading and surfing, and I have 16 processes. ) --69.181.232.116 08:16, 14 November 2005 (UTC)

[edit] Another Question

I've been getting these alot lately any ideas???--ineedhelp 06:51, 13 November 2005 (UTC)

I typically see this message on disks that are about ready to go bad. Get as much information off the disk as possible. Then run chkdsk to *possibly* fix the problem. If on a Windows 2000/XP machine, go to Start, click run, type 'cmd' without the quotes and hit enter. In the new window that pops up, type 'chkdsk a: /f /r /x' again without the quotes and hit enter, where a: is the drive that you are using when you experience that error. This will check the disk for bad spots, moving any data it finds in those spots to new areas and marking the old areas as bad. My suggestion would be to then move everything off that disk that you can and replace it. imsaguy
Yeah, that's a bad sign. I've seen floppy disks do this when they have bad sectors. Backup if you can, then try chkdsk, see if that helps any. If it doesn't, you should probably invest in a new hard drive. --Fastfission 01:00, 14 November 2005 (UTC)
The same goes for any sort of disk (floppy, hard disk, CD...) — I get these from time to time on old CD-Rs that have just been through too much. In case you're wondering, a cyclic redundancy check is a type of error-checking mechanism that Windows uses to make sure the file you're moving/copying is intact. And I would agree with the other posters - if you get this while moving files to/from a hard disk, get your files off there as soon as possible. If you get this while reading from a CD, then that CD is damaged, but you might be able to get your files by cleaning it off with a cloth (to get rid of stains, fingerprints etc). — QuantumEleven | (talk) 09:28, 14 November 2005 (UTC)

[edit] Statistical tables

Carole Winch e-mailed the following question to the help desk. I am taking the liberty of posting it here.

Hi I need to know how to access tables of values for the students t-test, or how to use the fx-83WA calculator to extract the p-value from the t -statistic

I have tried looking in various places without luck!

Hope you can help Carole Winch (Maths tutor)

Thank you in anticipation of your help. Capitalistroadster 09:04, 13 November 2005 (UTC)

Critical values for t can be found here (PDF file), as well as many other places on the web. This site will enable you to calculate probabilities corresponding to a given t-value and number of degrees of freedom. The two sites were on the first page of a Google search for "statistical tables": as I say, there are many, many sites which publish tables (as the information contained is not eligible for copyright). Physchim62 (talk) 11:28, 13 November 2005 (UTC)

[edit] Request for Diagrams - Fungal Enzymes

How can I find diagrams for the listed Fungal enzymes please? they are required for illustration purpose--195.93.21.103 11:03, 13 November 2005 (UTC); asparaginase, amylase, catalase, cellulase, dextranase, b-glucanase, glucoamylase, glucose oxidase, hemicellulase, laccase, lipase, pectinase, protease, rennet, tannase, xylanase

Structural or Ribbon? Id start with a college biochemistry textbook. --Artoftransformation 06:58, 14 November 2005 (UTC)
Your best bet would be to find the PDB file for the enzyme and then plug it into RasMol or similar piece of molecular modeling software. --David Iberri 01:03, 16 November 2005 (UTC)

[edit] CGA Monitors

Some question? [33] CGA was the first graphic standard for the IBM PC. ( 160x200x16c ), ) It can be emulated in VGA, by most SGVA graphics cards. --Artoftransformation 17:21, 13 November 2005 (UTC)

What would be your question? --R.Koot 21:59, 13 November 2005 (UTC)

[edit] Why is it important that only one sperm may fertilise one egg in reproduction

what do you mean "important"? it is a fundamental feature of sexual reproduction. in the case of asexual reproduction, you don't talk about sperms and eggs. If you can think of another method, involving several fathers, Nature hasn't :) dab (ᛏ) 14:25, 13 November 2005 (UTC)

Your question has two answers:

  1. The egg already has half a set of chromosomes for a new person. One sperm supplies the other half. Trying to incorporate more than one sperm's worth of DNA would probably lead to higher rates of chromosomal aneuploidy.
  2. It does seem necessary, or at least more efficient, for more than one sperm to participate in fertilization, though only one sperm ends up being incorporated into the nucleus and contributing its chromosomes.

Does that answer your question? alteripse 14:26, 13 November 2005 (UTC)

It only takes one sperm because it only needs one sperm.--Eye 21:37, 13 November 2005 (UTC)

[edit] quantum mechanics?

I am looking for Open Source software tools and/or libraries that can help me simulate (not 'solve', but propagate) many-body problems in classical quantum mechanics. dab (ᛏ) 14:29, 13 November 2005 (UTC)

If you find one, let me know too!! I'm actually doing research in this area, and it would be wonderful if there was such a thing. What sort/form of many body problems are you looking at specifically? --HappyCamper 16:48, 13 November 2005 (UTC)
The Models of Classical Quantum Mechanics, relating to Hydrino theory were constructed with Wofram Research's Mathamatica. They are avaible for download at blacklightenergy's webiste. I would love to know if you find any Open Source Software that works with Mathamatica Workbooks. --Artoftransformation 17:15, 13 November 2005 (UTC)
Maybe you'd be interest in this website? ☢ Ҡieff⌇↯ 17:23, 19 November 2005 (UTC)

[edit] Application of mathematics in Actuarial Science, Medicine and Engineering

Hi,

I am writing a paper on the application of mathematics in the following industries:

  • Actuarial Science
  • Medicine
  • Engineering

But I am unable to fine anything, please help

THANKS Kaydean Campbell

This is a very general question. Have you had a look at Engineering? The fields you mentioned all use computers, maybe Computer science will help.--Commander Keane 16:25, 13 November 2005 (UTC)
You could contact the Society of Actuaries.
You could ask a student in a nursing program. --Artoftransformation 17:10, 13 November 2005 (UTC)
Is the paper you are writing for your homework? If so, then read the articles that Artoftransformation has suggested that you read and then if you have any specific questions please ask them here. --hydnjo talk 19:26, 13 November 2005 (UTC)

For the medicine answer, you could even ask a doctor. Over 99% of the math used in clinical medicine by doctors and nurses is straightforward arithmetic and simple algebra: especially percentages, ratios, unit conversions. There is also some use of statistics and probability in devising and understanding research reports. alteripse 19:42, 13 November 2005 (UTC)

Of course the maths invovled in getting an MRI is more complicated.--Commander Keane 05:23, 14 November 2005 (UTC)

[edit] Planet VenusI

I could use some help answering some ? about Venus. I have searched the site but can not find these answers, the diameter of the planet- average day& average year on Venus. Also my opinion of the color of Venus is purple& gold. Would you agree? Thanks for any help you can pass on to me on this subject. SAVANNAH —Preceding unsigned comment added by 64.12.117.12 (talk • contribs)

If you had "searched the site", you surely would have looked at the article Venus, which answers all of your questions. --Kainaw (talk) 19:20, 13 November 2005 (UTC)
There is a table of physical characteristics on that page. In particular, it says that the year is approximately 243 days. The other values can be found by reading down the list carefully. --HappyCamper 21:20, 13 November 2005 (UTC)

[edit] What's this all about?

Image:AttemptSony.jpg
Image:Notwork.jpg


--Whatgives? 19:48, 13 November 2005 (UTC)

So? any advice? or what?--Whatgives? 00:06, 14 November 2005 (UTC)
Disable your firewall. --R.Koot 00:46, 14 November 2005 (UTC)

[edit] Slow page loading

This is perhaps a question for WP:HD but since it is only showing up here I'll ask here. Does the inclusion of an image within the question (like the one just above) cause the page to load more slowly, perhaps waiting for the image server? It seems so to me. I'm going to be bold and link instead of call the images above to see if it helps. --hydnjo talk 20:16, 13 November 2005 (UTC)

I've started a topic on the talk page. --R.Koot 21:13, 13 November 2005 (UTC)

[edit] Why are Hydrates formed?

Why would hydrates form? (preceding unsigned comment by 68.48.11.145 (talk • contribs) )

Hydrates are formed if they impart thermodynamic or kinetic stability to the chemical system. Let's take a substance X - If X forms a hydrate with water, it simply means that a bunch of water molecules surrounding molecules of X is more stable than if they were separate. But this is somewhat of an oversimplification. --HappyCamper 21:29, 13 November 2005 (UTC)

[edit] Computer

distinguish between Management Information System and "Information System" —Preceding unsigned comment added by 80.255.50.2 (talk • contribs)

'To err is human, but to really foul things up requires a comptuer' MIS systems typically have the ability to do either summories or ad-hoc reporting, where as Information Systems is a general catch all for any storage system. ( like a card catalog in a library ). --Artoftransformation 05:56, 14 November 2005 (UTC)

[edit] Law of expirementing with hydrates

What law illustrates the heating of a hydrate in order to get an anhydrous substance?

[edit] Venus

I have had conflicting answers to my ? on an average year on Venus is a year 243 days one site says a day on Venus corresponds to 243 earth days. Please Help Confussed —Preceding unsigned comment added by 64.12.117.12 (talk • contribs)

You're back again huh? Give me a minute. I'll help you out, I promise :-) --HappyCamper 22:23, 13 November 2005 (UTC)
From our article Venus, the diameter of the planet is about 12,103.7 km. The average day on Venus lasts about 243 days, and a year on Venus (the orbital period on the list to the side of the table) is about 224.700 days.
So, a "day" on Venus is actually longer than a "year"! Does this help clarify your questions now? --HappyCamper 22:28, 13 November 2005 (UTC)
I don't think that is correct. The article says one venus day takes 116.75 earth days. One venus year takes 224 earth days (1.92 venus days). --R.Koot 22:34, 13 November 2005 (UTC)
Check out [34] in the section "Retrograde motion". The 116.75 days is the synodic period. --HappyCamper 22:37, 13 November 2005 (UTC)
Indeed, according to NASA [35] 1 Venus day = 243 Earth days and 1 Venus year = 225 Earth days. --R.Koot 22:53, 13 November 2005 (UTC)
This was a confusing point for sure! No wonder why the IP kept coming back. I hope this was helpful for him/her and hopefully encourage them not to blank the page or use excessive caps here. --HappyCamper 23:04, 13 November 2005 (UTC)
I don't think I understand the sentance "Sun could be seen from Venus' surface, it would appear to rise and set in a 116.75 day cycle (Venus' synodic rotation period), and a Venusian year would thus last 1.92 Venusian "days""? Shouldn't the 116.76 be 121.5? --R.Koot 23:08, 13 November 2005 (UTC)

THANK you all for your info. I do not know what blank the page or that other thing is. This was my first time on this site an if I hit a wrong button sorry;;; please explain what those are.

'blank the page' means removing all the contents from a page, 'execessive caps' refers to WRITING IN CAPITAL LETTERS. Hope to see you around. --R.Koot 00:03, 14 November 2005 (UTC)
Umm, go up to your original question (Venus) and at the end of it (after the word "Confussed") skip every thing else and click on contribs. That way you can see all of your contributions here. hydnjo talk 01:05, 14 November 2005 (UTC)
Note that the IP in question belongs to AOL. Therefore, OP may very well not have been the vandal. --Pidgeot (t) (c) (e) 02:09, 14 November 2005 (UTC)
The article states that Venus has an extremely slow rotation of less than one rotation per Venusian year. This effectively means that it has a retrograde rotation, right? I've mentioned this on the talk page there as well. Also, the "Rotation period -243.0185 d" in the table looks rather puzzling. I'm not sufficiently on certain ground here to alter this myself. DirkvdM 10:04, 14 November 2005 (UTC)
The minus implies the retorgrade rotation, I think something like Rotation period 243.0185 d (retrograde) would be more informative. Retrograde means it rotate the otherway around, compared to earth, having a slow rotation doesn't necessarily imply a retrograde rotation. --R.Koot 15:41, 14 November 2005 (UTC)
Yeah, but slower than a year does. This is such a counterintuitive thing that I'd say it deserves a better explanation in the article, rather than a puzzling minus in the table. I added some text to the top section of the article. DirkvdM 09:28, 15 November 2005 (UTC)
Retrograde rotation means "opposite of the orbit". So, if you look from above and you see a planet going clockwise around the sun but spinning conter-clockwise, it is retrograde. It really has nothing to do with Earth except that the planets tend to always have the same orbit direction as Earth - so retrograde tends to be the opposite direction of Earth.
Venus spins in the opposite direction of the direction it orbits the Sun. It does so very slowly. The fact that is spins slowly does not make it retrograde. Other planets spin slowly without retrograde spin. The Moon, as another example, makes one rotation on each orbit of the Earth - that is almost as slow as Venus. However, it isn't retrograde. --Kainaw (talk) 20:44, 15 November 2005 (UTC)
I'm sorry, I didn't put that very clearly. I meant that it rotates slower than a venusian year (which is the way it was stated eralier). Anyway, I my edit in the article was clear enough and that matters most. DirkvdM 13:36, 16 November 2005 (UTC)

[edit] November 14

[edit] Algebra

Who started algebra in the past? —Preceding unsigned comment added by 70.236.189.93 (talk • contribs)

See Algebra#History. --R.Koot 01:08, 14 November 2005 (UTC)
Reading the Algebra article will give you some insight into the subject. And, if you do read it all you will know more about Algebra than any of your friends. hydnjo talk 01:20, 14 November 2005 (UTC)

[edit] Spin states of deuterium

Here's a question to chew on: I read somewhere the "...para-deuterium pD2 has a nuclear spin of I = 1..." - what is it trying to say? That the entire molecule has a nuclear spin of 1? --HappyCamper 02:02, 14 November 2005 (UTC)

No. Atoms have spins. The atomic spin that they are talking about is the spin moment of a single atom.

TEXT REMOVED "HyperPhysics (©C.R. Nave, 2005) is a continually developing base of instructional material in physics. It is not freeware or shareware. It must not be copied or mirrored without authorization. The author is open to proposals for its use for non-profit instructional purposes. The overall intent has been to develop a wide ranging exploration environment which could be of use to students and teachers."

[36]

But to answer your question directly:
Nuclide ----- Nuclear spin I ----- Magnetic momentm mu in mu mN
2H(D)-------------1 --------- +0.8574376*
  • For a proton with g = 5.5857 the quoted magnetic moment is m = 2.7928 nuclear magnetons.
Data from V. S. Shirley, Table of Isotopes, Wiley, New York, 1978, Appendix VII.
This is the basis for Nuclear Magnetic Resonance Imaging.

--Artoftransformation 05:53, 14 November 2005 (UTC)

everything I know, I learned from 10^100.

[edit] Netscape Favicon

Why do a lot of websites have Netscape's icon as their favicon.ico file?

Examples:

http://home.att.net/favicon.ico

http://cia.gov/favicon.ico

Theshibboleth 06:57, 14 November 2005 (UTC)

Mostly its leftover from the days when Netscape ruled the world. I never knew what that file was for, until I looked at your links. Thanks. Now I know how to fix all my favicons on my toolbars.
See article [Favicon]
--Artoftransformation 06:13, 14 November 2005 (UTC)
You mean favicon? Anyway, I'm fairly sure that sites that have Netscape's icon are using a Netscape-branded web server which uses that favicon by default, and the server administrators haven't bothered to change them yet. Garrett Albright 14:05, 14 November 2005 (UTC)
Either that or they were originally written with some sort of Netscape-based tool which inserted it as default (Netscape Composer or something like that). As an aside, have you checked out what the CIA lists their site's keywords as in their META tag? Fairly humorous...:
US Central Intelligence Agency, Central Intelligence Agency, CIA, C.I.A., cia, c.i.a., Intelligence, Government, United States, Goss, Director of the Central Intelligence Agency, directors of central intelligence, cia homepage, cia home page, cia factbook, cia fact book, cia world factbook, cia world fact book, world factbook, world fact book, intelligence community, US intelligence Community, spy, spies, the company.
Does not seem to have helped their ranking for searches like "the company". --Fastfission 04:12, 15 November 2005 (UTC)

[edit] Gender and blood

Say you had a drop of blood and wanted to know whether it came from a man or a woman. How difficult would it be? Would the easiest way be to look for the X or Y chromosomes in the blood cells? Can you even tell X and Y chromosomes apart with an optical microscope? —Keenan Pepper 04:37, 14 November 2005 (UTC)

Well for starters, red blood cells have no nuclei and no chromosomes, so there wouldn't be much in the way of visual clues to sex unless you could pull down their little pants. White blood cells can be stained to show nuclei with Barr bodies under the microscope. A Barr body is a partially inactivated second X chromosome and, though not infallible, is generally a better clue to female gender than a pink hair ribbon. Staining for Barr bodies is old technology however, and if you want something slightly newer and less fallible, you can rely on the good old peripheral blood karyotpe. Perhaps the most up-to-the minute test for sexing blood is detection of the SRY antigen, a pretty reliable indication that the owner also sports a set of testicles. So take your pick. alteripse 05:26, 14 November 2005 (UTC)

Alteripse, could you also measure the hormone levels in blood and figure out the gender that way? I was thinking testosterone and oestregen (modulo the small group of steroid-taking women and male sex offenders being treated with female horomones). Not my field, but just curious as to whether it would work. --Robert Merkel 05:40, 14 November 2005 (UTC)
You could do that if you measured several hormones for adults, but all sex hormone levels are indistinguishably low during childhood. The SRY probe would be my preference for maximum (not perfect) gender identification regardless of age. alteripse 16:29, 14 November 2005 (UTC)
This depends a lot on just how much time, money, and blood you have available. Instead of doing the classic karyotype, you could probably speed up the process by using a technique like FISH–fluorescence in-situ hybridization–to automate the identification of each chromosome. If you're just looking for gender and not chromosomal abnormalities–but you want to avoid any problems related to hormone therapies mentioned by Robert Merkel–you could do a DNA isolation from the blood and probe for Y chromosome specific genes using PCR. That would be pretty quick and easy, and nearly bulletproof.
If you start getting into some of the less-common border cases, you can see things like 46XY karyotype combined with negative SRY antigen and malformed genitalia. (See this page, warning: some images may not be appropriate for some workplaces.) TenOfAllTrades(talk) 15:20, 14 November 2005 (UTC)

[edit] Which is Correct Molar Mass or Molecular Weight?

Which is correct to use? molar mass (MM), a more recently introduced term, or molecular weight (MW), an older term still in widespread usage?.HappyApple 06:58, 14 November 2005 (UTC)

  • IUPAC will let you have relative molecular mass, relative molar mass or simply molar mass. WikiProject Chemicals tends to use molar mass because it has units (g/mol) whereas the other two are dimentionless: editors like putting units in tables, even where they don't belong... The other advantage is that molar mass and relative molar mass are general terms, whereas relative molecular mass can only be used for molecular compounds (i.e. not sodium chloride, for example). The links (to PDF files) are from the online version of the IUPAC Compendium of Chemical Terminology, better known as the "Gold Book". Physchim62 (talk) 07:38, 14 November 2005 (UTC)
    • Don't they mean different things?--Hello'from'SPACE 00:08, 15 November 2005 (UTC)
(Note: I edited the signature above. It had unclosed HTML tags changing font size and color for the rest of the page.) --Kainaw (talk) 00:29, 15 November 2005 (UTC)
Literally, they mean different things, but this depends on who you talk to. I use whichever term that is clearest based on the context. If I were on the moon, I'd definitely use "molecular mass". We should contact NASA and see what they have to say! --HappyCamper 01:37, 22 November 2005 (UTC)

[edit] Fonts

I am looking for fonts for the following languages/scripts:

Does anyone know where I can download fonts for these languages so that when text is cited from them it is displayed properly? Because Wikipedia makes such extensive use of relatively uncommon fonts there should be some sort of technical support page for fonts.

Theshibboleth 08:16, 14 November 2005 (UTC)

Have a look at Free software Unicode fonts. --Heron 20:40, 14 November 2005 (UTC)

[edit] Electrostatics

Ques: Two point charges of values q and 2q are kept at a distance d apart from each other. A third charge Q is to be kept along the same line in such a way that the net force acting on q and 2q is zero. calculate the position of charge Q in terms of q and 2q?

reply on: [removed]

DYOH, and don't post your email address. Thanks. Garrett Albright 14:03, 14 November 2005 (UTC)
That means Do You Own Homework. DJ Clayworth 18:25, 14 November 2005 (UTC)

[edit] Mathematical Logic - Some Fundamental Results

The above section named "Some Fundamental Results" in the page "Mathematical Logic" has been changed by the user Otto ter Haar on the 9th of October. The old text read: "Given a first-order formula as its input, the procedure eventually halts if the formula is valid, and runs forever otherwise." The new text reads: "Given a first-order formula as its input, the procedure eventually halts if the formula is valid or not valid, and runs forever otherwise." I do not know or could not find out, what motivated ter Haar to enter this change but it would be an incredible (and unbelievable) result, contradicting all our knowledge of computational theory and computability. The only reason - which I could imagine - to justify this statement, i.e. that there is a theorem prover, which works for valid as well as invalid formulas, is to assume certain finite domains, and do model checking. Nevertheless, this should be somehow included in the modification of this article. Otherwise, it leads to a contradiction with the statement that first-order logic is recursively enumerable (which means all valid formulas can be constructed) and that it is NOT recursive (which means that there is no decision procedure for saying whether a formula is valid or not) - and these two statements are enormously important results for computational theory and are general textbook knowledge. It is also unclear, in what situation the procedure would not terminate - since the modified statement implies that the procedure (the theorem prover) always halts (since in standard logic, there is only true or false). It would be appreciated to get some feedback, especially by ter Haar, on this change and my concerns about it.

Christel Kemke

Well, a good place to discuss that would be the talk page for that article.
That said, it seems to me that Otto is right. You can run a theorem-prover starting from the axioms of logic, and at some point, if a hypothesis is provable or disprovable, you will prove either the hypothesis or its negation. I may be thinking of this wrong, as I'm not an expert in this area. But something that makes me doubt your explanation is that you are confusing "true" and "false" with "provable" and "disprovable". By Godel's incompleteness theorem, there must be statements that are neither provable nor disprovable, so the procedure does not always halt. rspeer 15:25, 14 November 2005 (UTC)

[edit] a system

what is a system/ why we refer to a computer as a system

Have you read our article on systems? That should answer both questions readily. — Lomn | Talk / RfC 18:42, 14 November 2005 (UTC)

[edit] geographical landforms, erosion

What is the difference between a bluff, a butte, and a mesa? --165.83.196.106 19:32, 14 November 2005 (UTC)

You mean a bluff, a butte, and a mesa? TenOfAllTrades(talk) 20:15, 14 November 2005 (UTC)

[edit] November 15

[edit] What does the measurement "uF" stand for?

What does the unit of measurement "uF" stand for?

I'm pretty sure it is μF, which stands for microfarads. Titoxd(?!?) 01:58, 15 November 2005 (UTC)
To clarify it is μF and this stands for microfarad which is a measure of electical capacity in a capacitor.
  • Note that though it should be μF for microfarad, it's very common in places that don't do advanced fonts (electronics catalogues and the like) to find it as "uF". --Bob Mellish 03:59, 15 November 2005 (UTC)

[edit] vi and text replacement

Hello! I'm trying to learn how to use vi. Could someone show me how to make a text substitution in vi? I'd like to replace the word "apple" with "orange" in a text file that I have. Thanks! --HappyCamper 02:47, 15 November 2005 (UTC)

First, make sure you're in normal mode by pressing ESC (the escape key). Assuming you want to change all occurrences throughout the file, one command will do the trick:
:%s/apple/orange/g<ENTER>
This can be broken down as:
  • : - activate command-line mode
  • % - a range of lines spanning from the first line to the last (i.e. the whole file); without this, the command operates only on the current line
  • s - use the substitute command
  • /apple/orange/ - "apple" is the pattern to search for, while "orange" is the text to replace it with. The pattern has a syntax similar to regular expressions if you want to get fancy with it.
  • g - Global substitution; without this, only the first match in each line is substituted.
If you want to step through matches one at a time and decide whether to change each of them, replace the "g" flag with "cg". You can find more information by typing ":help :s" (assuming you're using Vim), and if you haven't found it already it would probably be a good idea to go through the tutorial (":help tutor") as well. Hope this helps! —David Wahler (talk) 03:13, 15 November 2005 (UTC)
Or, assuming you're currently positioned at the occurrence of "apple" you want to change (one of many ways to get there would be to type "/apple<ENTER>" without the quotes), entering "cworange<ESC>" (without the quotes) changes the word. Typing ":" as suggested above essentially takes you out of "visual" mode and lets you enter editing commands compatible with the line-oriented (non-visual) UNIX editor ed (vi is based on ex, which is a variant). In visual mode, any of the positioning commands ("w" to space ahead one word, "$" to move to the end of the current line, "l" to move right a character, etc.) can be prefixed with "c" which, rather than just positioning the cursor, changes the text from the current cursor position to wherever the cursor would end up as a result of the move command to what you type, terminated by entering <ESC> (similarly, prefixing "d" deletes through that point). If you're in a command line shell on a linux or unix system, "man vi" should give you more details. -- Rick Block (talk) 15:15, 16 November 2005 (UTC)
Thanks so much!!! This was very, very useful! :-) --HappyCamper 02:54, 21 November 2005 (UTC)

[edit] Question about light and eye.

If you step out of a lighted house into a dark backyard what sudden change occurs in your eye?What is this process called?

Dilation of the pupil, or the abnormal version, mydriasis? (I'm not sure how appropriate it is to redirect pupil dilation to mydriasis...) AySz88 04:05, 15 November 2005 (UTC)

The two are not the same. Mydriasis is used for excessive, drug-induced, or neurologic-lesion-induced dilation. Partly analogous to the difference between erection and priapism. alteripse 11:25, 15 November 2005 (UTC)


Don't forget the other, albeit slower mechanism the eye uses to adapt to darkness-- the synthesis of rhodopsin in the rod cells of the retina. Light exposure depletes rhodopsin from these photoreceptor cells, while darkness permits a metabolic re-stocking of this substance. Actually, full darkness is not necessary in order to replete rhodopsin stores; the rods are insensitive to red light, which permits darkness adaptation with the use of red adaptation goggles. Using these devices, the eye can continue to function using solely the color-descriminating cone cells' ability to respond to red light, while the rods adapt to darkness.--Markitos76 16:15, 15 November 2005 (UTC)

[edit] Can Menstruation will be happend without releasing egg?

Can anyone help me to get the answer for the question"Can Menstruation will be happend without releasing egg? "

  • See menstruation which says: During the menstrual cycle, the sexually mature female body releases one egg (or occasionally two, which might result in dizygotic, or non-identical, twins) at the time of ovulation. The lining of the uterus, the endometrium, builds up in a synchronised fashion. After ovulation, this lining changes to prepare for potential implantation of the fertilised egg to establish a pregnancy. If fertilisation and pregnancy do not ensue, the uterus sheds the lining and a new menstrual cycle begins. Therefore, my answer would be no. - Mgm|(talk) 11:14, 15 November 2005 (UTC)

But this is the problem with theoretical answers because the answer is certainly yes. Menstrual bleeding without ovulation is called anovulatory bleeding. It is the most common type of infertility. It characterizes the menses of the first year after menarche in most girls. It characterizes many of the menses as menopause approaches. Women with polycystic ovary syndrome and several other types of hormone imbalances typically have menses despite chronic anovulation. Anovulatory menses are characterized by irregularity, unpredictability, variation of length and heaviness from period to period, lack of mittelschmerz, and lack of premenstrual physical symptoms. Finally, any woman taking birth control pills typically has menses without ovulation. alteripse 11:23, 15 November 2005 (UTC)

[edit] Chemistry / instrument for finding mass

What instrument is best suited in finding the mass of an object?

Here on Earth where we have strong-ish gravity, probably a balance or weighing scales. These would not work in space however. Smurrayinchester 14:58, 15 November 2005 (UTC)
In college we use to use a balance scale. Actually this will work in space also, if you are on a space station or something which rotates to provide simulated gravity.
In zero gravity, you can find mass by measuring the acceleration of the object when you input some amount of force. F = ma -> m = F / a. But this is precisely what we do when we use a scale: F = weight, a = gravity. ☢ Ҡieff⌇↯ 17:04, 15 November 2005 (UTC)

[edit] Aqua regia

Is Aqua regia dangerous to human's health? roscoe_x 12:47, 15 November 2005 (UTC)

Only if you touch it, or inhale the fumes. In general, liquids that can dissolve gold and platinum are bad for human health. TenOfAllTrades(talk) 12:53, 15 November 2005 (UTC)
In spring 1998, a female graduate student of nuclear biology of Taiwan's National Tsing Hua University killed another female classmate at school over a love dispute. She strangled the woman and destroyed a part of the victim's body using self-made aqua regia. Anyway, most of the body was still there lying of the floor of an auditorium. It was found after a weekend break.
They searched the victim's e-mail and focused on her killer immediately. The suspect was caught in a few days and was sentenced for 18 years. She baptized while in jail. The principal of the University managed to defend her and visit her frequently after she was prisoned. She is expected to be released on 2007 if she's good enough.
Aqua regia is surely harmful. However, you may want a lot of it to dissolve a dead body. -- Toytoy 14:01, 15 November 2005 (UTC)We used to use a balance scale to weigh objects.
  • This seems like a semi-common confusion. "Gold disolves in aqua regia" doesn't mean that only gold disolves in aqua regia. Aqua regia can disolve just about anything; the point is, gold won't disolved in any(?) other acid. --Bob Mellish 17:15, 15 November 2005 (UTC)
Incidentally, either this or simply nitric acid is used in Oscar Wilde's The Picture of Dorian Gray for the same purpose, more successfully. ‣ᓛᖁ♀ᑐ 21:30, 15 November 2005 (UTC)

[edit] biochemistry of amino acids

Dear Sir(s),

Good day. I was wondering about the structure of the amino acid Isoleucine, whether it is the same thing as "acetyl-DL-leucine ", or not.

Thank you for cooperation

Dr. Samaah Zohair. Alexandria, Egypt.

The difference between leu and ile is which carbon a methyl group is attached to, so ile is not simply the acetylated form of leu. alteripse 01:34, 16 November 2005 (UTC)

[edit] Quarks

what is the history of quark, that would be easyly written on a time line? --70.105.42.63 20:19, 15 November 2005 (UTC)

Some important dates related to quarks are listed in Quark#History. --R.Koot 20:27, 15 November 2005 (UTC)

[edit] Debian

not a science question, strictly, but I guess I am most likely to get an authoritative reply here :) -- I was updating my debian distribution with dselect, thinking no evil, and suddenly it turns out some kde packages are mutually exclusive, and at the same time dependent on each other. I spend time deinstalling and installing stuff, eventually I'm down to twm, with neither kde or gnome working. I figured there is maybe something wrong with my mirror and tried to get a list of debian mirrors. Lo and behold, http://www.debian.org/mirror/list gives me an empty list! Can anyone help me get my kde running again, and/or tell me where all the debian mirrors went? dab (ᛏ) 20:23, 15 November 2005 (UTC)

I don't know what's happened to the mirror list on the Debian website (or on deb's www mirrors), but the FTP servers have an (apparently) good list, see ftp://ftp.debian.org/debian/README.mirrors.html (or your local mirror, ftp://ftp.COUNTRY.debian.org/debian/README.mirrors.html). I've no ideas on the making KDE work front, though. -- AJR | Talk 00:23, 16 November 2005 (UTC)

[edit] Toxic steroids

  1. What are some common steroidal alkaloids?
  2. Other than batrachotoxin, which steroid compounds are toxic?
    1. Are they typically neurotoxins?

‣ᓛᖁ♀ᑐ 21:10, 15 November 2005 (UTC)

  • Solanine and samandarin are toxic steroidal alkaloids which are common enough to have Wikipedia articles written about them. Many steroid hormones are toxic in the wrong dose at the wrong time (and especially to the wrong gender, for sex hormones), vitamin D is notoriously toxic in overdose, so I guess it really depends on the level of toxicity you're interested in (or interested in avoiding!) Hormonal toxicity is not neurotoxicity, so I guess the answer to your third question has to be no. Physchim62 17:44, 16 November 2005 (UTC)

[edit] Why did he say Ontogeny recapitulates phylogeny?

Why did Ernst Haeckel say "Ontogeny recapitulates phylogeny"? What was his point?

Have a look at Recapitulation theory, under the first heading, "Haeckel's theory". It's a pretty concise explanation. Shimgray | talk | 21:38, 15 November 2005 (UTC)

[edit] some beliefs of Chinese culture I would like to verify

My mother is not the superstitious type or anything, but she tells me some things I don't find documented in the standard textbook but tells me it's part of Chinese culture and medicine; but she was a former teacher herself so I'm just wondering perhaps whether some of it is real and documented, but not so common (ie. something like acupuncture?), undocumented for Western medicine but plausible, or false (perhaps misconceptions from my grandmother who is not prone to superstition either but perhaps picked up from culture as some urban legend or something); I can't recall most of these at the moment, but some of them are:

  • Eating too much kangkong (Ipomoea aquatica) makes you weak (I wrote a scientific "answer" in there but it's really filler), supposedly becausethe hollow stem makes you weak and hollow like it (I think this was just a metaphor and not the actual reason for the belief?).
  • Eating cold porridge will nearly ALWAYS result in a stomach ache (or at least 90% of the time) - doesn't seem to do anything with germs, if you refrigerate porridge and eat it later, you will get a stomach ache or its very likely you will. The explanation is that it will give you "wind" in your stomach, with my guess for the elaboration, that it is believed that coldness is incompatible with the nature of porridge (the latter part is my guess because Chinese culture always tries to maintain a balance between "heaty" and "cooling" foods, not to be taken literally, a refrigerated food is not always cooling and vice versa). This always seems to be true a lot: nearly everytime I ate porridge cold I always had a stomach ache afterwards (the last few times I didn't think it would matter and went against my mother's advice; it seemed I was mistaken)...nothing too sharp; sort of like a dull ache, not of satiation either.
  • Males shouldn't eat overnight eggs (not sure whether this is just chicken eggs, or all eggs) because it will contribute to infertility.

If I recall any others I'm also bound to ask them again. Oh by the way, what happens to convection in zero gravity?

-- Natalinasmpf 22:28, 15 November 2005 (UTC)

Are you eating porridge with milk or water. Every Chinese person I work with says that cold milk gives them a stomach ache. Some claim that they get a stomach ache when they see me drink cold milk every morning. --Kainaw (talk) 23:36, 15 November 2005 (UTC)
Congee ... it often involves milk, I think. But my mother doesn't mention anything about the milk being the factor, and I sometimes get an ache with a water-based porridge.
I should also point out that the Chinese were are visiting from China (and many who were raised there) have trouble with cold drinks as well. They even heat up Coke before drinking it. They say that kids in the larger cities are getting used to cold drinks, but the older people are stuck in their ways. --Kainaw (talk) 00:58, 16 November 2005 (UTC)
I'm not familiar with kangkong specifically, but I can make some guesses. Leaves generally have little nutritional value and are difficult for humans to digest. Although they might fill you up, eating too many will make you sick and give you diarrhea. Leaves make a poor staple compared to rice because they contain very few calories, for example two cups of rice contain 400 calories, while two cups of watercress (a leafy vegetable) contain only 8. --Avijja 03:28, 16 November 2005 (UTC)
I am a 36-year-old Chinese born and live in Taiwan. I don't find your mother's ideas practiced here. My father was born in Southern China and was grown up in Beijing. He also haven't heard of these things.
  • Ipomoea aquatica is a daily vegetable in Taiwan. If you like vegetables, you can eat it here almost everyday. I don't find its hollow stem leads to any metaphorical reading here. Some vegetables such as pineapple (sounds like "good fortune") and white turnip (also sounds good) are given as gifts though. A quick web search only results in a vague taboo: Do not eat Ipomoea aquatica during winter [37]. This is not widely practiced. I haven't heard of it. However, if you belong to the "cool" type, an herbal doctor may suggest you to eat less Ipomoea aquatica and eat more lychee which is a "heaty" food. [38]
  • Most Chinese are not heavy milk drinkers because they lack of an enzyme to digest lactose. And in many parts of Asia where dairy cows are in short supply (farm lands are used to grow rice and other food crops), people drink milk prepared from hot water and imported powdered milk at home. If you live in a typical Asian city, you may see many 4- to 6-story buildings are built without an elevator. Why? Land is so expensive, you just cannot afford to waste it! If you live inside such an apartment, you don't want to buy liquid milk. By the way, you don't have a place to park your car. So you may need to carry the foods from the supermarket (usually not far away) to your home on foot or riding a motorcycle. Anyway, many Asians are trained to drink hot milk. It was not until the 1980s did they invent milk powder that dissolves in water at room temperature.
  • Cold porridge is not welcomed here and in most of China. Cold porridge is not tasty because it does not smell that good. There's a Chinese saying, you wait for your porridge; your porridge does not wait for you. That means you have to wait for several hours until the rice in your porridge is almost dissolved. People love that texture. Some even to used a candle to cook a small pot of porridge over night. And when your porridge is ready, you eat it while it's still hot. People love the smell of the condensed glue-like mixture of rice and water.
  • Overnight eggs are not unedible here. Many of us were bringing eggs cooked last evening in our lunch boxes to school. In many Asian countries, children and some adults take lunch boxes prepared last evening to school or work (see the "Outside Mumbai" section of dabbawala). Trust me, they love their eggs. People in China usually hate overnight tea. People DO hate overnight tea. You don't want to drink overnight coffee, do you? Are you serious about your freshly brewed coffee? We are serious about our tea. That's the point.
There were some food taboos circulated in China such as a widely referenced chart of foods you don't want to eat together printed on the back of a lunar calandar [39] (similar to the Farmer's Almanac of the West) (e.g.: this Chinese page; top left: spinach and milk gives you diarrhea). However, many such taboos are no longer be taken seriously. Debunking these myths had been popular elementary school science project topics in Taiwan during 1950s to 1970s. Many of today's kids simply do not know anything about these taboos.
The food chart are always printed on the back of a lunar calandar. And its list of deadly food combinations are never unified. Its format is always two badly drawn foods + symptom + cure. Such as:
2. Carp and liquorice results in death. Cure: 75g of Ipomoea aquatica extract.
3. Dog and mung bean results in stomach rupture. Cure: 40g of liquorice boiled in water.
7. Frog boiled in tea results in death. Cure: You're dead.
9. A pregnant woman must not eat crabs. Or your baby will be gone and there's no cure. [40]
31. Crab and mandarin oranges are poisonous. Cure: Take some garlic juice. [41]
52. Milk and spinach gives you diarrhea. Cure: mung bean soup. [42]
Some food combinations and cures are just too funny to be true. I love them. -- Toytoy 15:12, 17 November 2005 (UTC)
I really enjoyed reading your write-up, Toytoy. I hope you find an article to add this delightful information to because I think others would want to read this. The deadly food chart lunar calendar was very amusing. Thank you for sharing these cultural tidbits with us. --Avijja 10:33, 18 November 2005 (UTC)
These lunar calendars are usually free gifts printed by temples. They are not your typical wall calendars (usually free gifts printed by rice shops or other "secular" business). The lunar calendars (農民曆; nonmin li; farmer's calendar) are used by farmers (time to plant/harvest ...) and ordinary people as well (when to/not to travel, have a wedding, moving, grand opinging, start building something ..., feng-shui or something like astrology). You may find some of them include updated modern life information (BMI and GI; for Buddha's sake). However, I don't see these things very often during the last couple of decades. Many families used to place a copy of the calendar in their living rooms. Some scholars study the sociological aspects of these calendars. You may even find teachers who teaches you to decipher the ancient jargon-filled small print.
Here are copies of the lunar calendar from an online book seller in Taiwan: Calendar for 2006 (NTD88 or less than US$3), Calendar for 2004 (NTD100 or about US$3). These covers are unlike the traditional ones (red background + lots of cheesy symbols of long life and good luck such as an old man and many fat kids in traditional custome with a big red peach and a white crane!). No wonder people love these free booklets (only if you go to a temple often, I guess).
I found a Taiwanese calendar printer here. If you want to give calendars to your customers, you can ask them to print your personalized calendars (100 copies minimum). However, I find the covers just too modernized. And the back cover, used to be the cheesy foods-that-kill-you chart, now becomes a real calendar (the small Chinese letters are lunar dates). No fun at all. I miss the good old days! By the way, this page talks about arthritis, gout and osteoporosis. This is really too modernized for my taste. :)
This eBay page of a 1990 calendar is partially in English. However, the cover is not traditional. The Nankunshen Temple is one of Taiwan's oldest and largest. -- Toytoy 13:30, 19 November 2005 (UTC)
It was also asked what happens to convection in zero g. I've clarified in the article that it doesn't occur. BTW, without convection, a flame behaves very differently in zero g. Here's a link[43]. Samw 04:34, 19 November 2005 (UTC)

[edit] Hair Synthesis

Briefly describe how mammalian hair is synthesised in the relevant organs.

[edit] November 16

[edit] Identifying a stroke

I received an email with the following information:

RECOGNIZING A STROKE Thank God for the sense to remember the "3" steps. Read and Learn! Sometimes symptoms of a stroke are difficult to identify. Unfortunately, the lack of awareness spells disaster. The stroke victim may suffer brain damage when people nearby fail to recognize the symptoms of stroke. Now doctors say a bystander can recognize a stroke by asking three simple questions: 1. Ask the individual to SMILE. 2. Ask him or her to RAISE BOTH ARMS. 3. Ask the person to SPEAK A SIMPLE SENTENCE (Coherently) (i.e... It is sunny out today) If he or she has trouble with any of these tasks, call 0-0-0 Immediately and describe the symptoms to the dispatcher. After discovering that a group of non-medical volunteers could Identify facial weakness, arm weakness and speech problems, researchers urged the general public to learn the three questions. They presented their conclusions at the American Stroke Association's Annual meeting last February. Widespread use of this test could result in Prompt diagnosis and treatment of the stroke and prevent brain damage. A cardiologist says if everyone who gets this e-mail sends it to 10 people;you can bet that at least one life will be saved. BE A FRIEND AND SHARE THIS ARTICLE WITH AS MANY FRIENDS AS POSSIBLE, You could save their lives.

Is this correct? - Ta bu shi da yu 01:14, 16 November 2005 (UTC)

It seems like a reasonably reliable screening method for a stroke, but I have trouble imagining a lot of lives saved. For this to actually save a lot of lives, the following facts would need to be true: (1) a large portion of strokes are misinterpreted as something else that does not seem to require urgent care, (2) a large portion of strokes go without early treatment that would lead to a fulller recovery than commonly occurs at present, (3) this screen would lead to an increased proportion of stroke victims getting early care that would produce a better outcome than getting later care. This is not my area of expertise but I suspect all three propositions are somewhat debatable. alteripse 01:24, 16 November 2005 (UTC)

There is a fairly complete discussion of this on Snopes.com here --DannyZ 02:02, 16 November 2005 (UTC)

[edit] Divergence and curl aren't enough

If you know the derivative of a function, then you know the function up to a constant. If you know the gradient of a scalar field, then you know the field up to a constant. But even if you know both the divergence and the curl of a vector field, that's not enough information to determine the vector field up to a constant. For example, <x,-y,0> has zero divergence and zero curl but it's not a constant. Is there a third property of a vector field that, together with divergence and curl, provides enough information? —Keenan Pepper 01:28, 16 November 2005 (UTC)

I think you might need all partial derivatives of each component. After all, you have those (in the form of a vector) with the divergence of a scalar field. The curl and the divergence only give you four equations (three for curl, one for divergence) when I suspect you need nine. -- SCZenz 09:35, 16 November 2005 (UTC)
Hmmm, if I'm interpreting covariant derivative correctly, the covariant derivative of a 3D vector field would be a 3x3 matrix. Then the trace of this matrix would be the divergence, and the curl would be... something involving a permutation tensor or something. This is complicated; I think I'll just wait until I take tensor analysis in a few years. —Keenan Pepper 16:32, 16 November 2005 (UTC)
Yeah, that's right. Another way of saying it is just that \frac{\partial f_i}{\partial x_j}, where the fi are the components of the vector field and i, j=1, 2, 3, can be written as a 3x3 matrix containing the elements you need to know. By the way, the curl is just given by (\nabla \times \bold{f})_i = \epsilon_{ijk}\frac{\partial f_k}{\partial x_j} -- SCZenz 17:09, 16 November 2005 (UTC)

[edit] largest satellite in the solar system?

largest satellite in the solar system?

Well, Jupiter itself is a "satellite" of the Sun, but I think you're looking for Ganymede. —Keenan Pepper 01:52, 16 November 2005 (UTC)
Titan (moon) is bigger than Ganymede Theresa Knott (a tenth stroke) 06:34, 16 November 2005 (UTC)
Um, according to Wikipedia and several other sources Ganymede is larger that Titan in both size and mass. What's your source? —Keenan Pepper 16:08, 16 November 2005 (UTC)
Ganymede is bigger than Titan in terms of mass, and has a larger diameter than Titan minus its (rather thick) atmosphere. Titan + its atmosphere has a larger diameter than Ganymede, and because until recently we've had trouble penetrating Titan's atmosphere, this led to confusion about how big it really was. From Titan:
Titan is [...] the second largest natural satellite in the solar system after Ganymede. It was originally thought to be slightly larger than Ganymede, but recent observations have shown that its thick atmosphere reflects a large amount of light causing an overestimation of its diameter.
— QuantumEleven | [[User_talk:QuantumEleven|(talk)]] 16:28, 16 November 2005 (UTC)

[edit] creatinine

I would like to know what is the normal range of creatinine levels for a woman taken from a urine test. Thanks --01:50, 16 November 2005 (UTC) Nadia

See our article on creatinine, down at the bottom. —Keenan Pepper 01:54, 16 November 2005 (UTC)

Notice that a creatinine measurement is nearly always a blood test, not a urine test. There is also a more complicated test of kidney function called a creatinine clearance test which involves simultaneous collection of both blood and urine. alteripse 02:15, 16 November 2005 (UTC)

[edit] what is leukopenia?

See our leukopenia article. Theresa Knott (a tenth stroke) 06:37, 16 November 2005 (UTC)

[edit] About Chicken Eggs

AS per the science I would like to know. Is Chicken Egg Vegetarian food Or Non –vegetarian Food? I think world vegetarian organization accept it as a Vegetarian Food. So how we accept it?. I kindly request for Answer.

Opinions differ. See Vegetarianism. Some people who call themselves vegetarians won't eat eggs; others will. A word for vegetarians who eat eggs and drink milk is ovolactovegetarians. A word for vegetarians who don't eat eggs or milk is vegans. - Nunh-huh 06:43, 16 November 2005 (UTC)

You may already understand that "vegetarian" is more a cultural category like "kosher" than a scientific category. I only mention this because you asked at the science desk. alteripse 11:48, 16 November 2005 (UTC)

From what I know, chicken eggs, that we eat are unfertilised, thus we are not eating any meat. However, it isn't a vegetable. Akamad 23:25, 16 November 2005 (UTC)

  • This is a perfect example of how this is a cultural not a scientific category. The entire biological world would consider an unfertilized egg part of an animal (as opposed to being a plant or a mineral), but apparently a haploid gamete is "fair game" (if you will pardon the expression) for vegetarians by someone's rules. alteripse 01:18, 17 November 2005 (UTC)

[edit] FREQUENCY

WHAT IS THE VIBRATIONAL FREQUENCY IN HERTZ (hz) OF HYDROGEN, OXYGEN, AND WATER H20?

Water has several different frequencies associated with it, because there are multiple ways it can vibrate. You can see some of those frequencies here, although I believe you'll have to multiply by the speed of light to get the frequency in hertz. I found those by googling for "vibrational modes" of water—I'll let you look for oxygen and hydrogen on your own. (Being diatomic molecules, they'll be simpler.) -- SCZenz 09:46, 16 November 2005 (UTC)
P.S. Per the instructions at the top of the page, please don't type in all caps. And see "do your own homework" for the reason I'm leaving some of this for you to do on your own. -- SCZenz 09:46, 16 November 2005 (UTC)

[edit] Building a cell phone

How would one go about building a cell phone? Even if one were succesful at this endeavor, would it even be possible to get any service? I was really surprised to see how little information I was able to find about this. I guess it's just not a practical thing to do. Theshibboleth 08:57, 16 November 2005 (UTC)

Presumably some of the components are patented, and so you'd need to reverse engineer them to make one legally (or get permission). The permission seems unlikely, and generally reverse-engineering a piece of complicated electronics is only feasible for a big electronics company. Come to think of it, since many of the components are electronics in the first place, you'd have to be an electronics company to put those together—unless you just bought a few pieces and hooked them together, which might be feasible. -- SCZenz 09:39, 16 November 2005 (UTC)
Howstuffworks.com has an article on how cell phones work. Not very technicle but there is some info available. Akamad 23:29, 16 November 2005 (UTC)
  • It's essentially a digital, GHz-frequency radio transmitter/receiver. So if you can build one of those, you're golden. If you look up the standard for GSM phones, which I think is readily available (probably on the web somewhere), IIRC it covers frequencies, data formats, etc., needed to interoperate with the standard. Of course there's also an authentication method so that only authorized units will get service. (I remember there's a interesting bit in the standard describing how each phone simulates a tiny bit of static during the "blanks" in conversation, otherwise people tend to think they've been cut-off.) --Bob Mellish 23:53, 16 November 2005 (UTC)
  • Apparently at least one person thinks it's possible: [44] The project was linked from Boing Boing just a week ago. —David Wahler (talk) 01:45, 17 November 2005 (UTC)
  • If you're determined enough, you can make one out of embedded computer parts, which would be very primitive, but it will work. I am thinking you could come up with one of those WWII sets which weighed 10 pounds and was as big as a textbook. -- Natalinasmpf 14:18, 17 November 2005 (UTC)

[edit] agricultural hollow blocks

Hi!!! We have an investigatory project in our school and our topic is all about agicultural hollow blocks. I need to know the procedure, materials, background, introduction and abstract of this project. Thanks!!!

It sounds like you need to do your own homework per the instructions you read at the top of the page. Try searching agricultural hollow block at Google for starters. — Lomn | Talk / RfC 15:39, 16 November 2005 (UTC)

[edit] Bermuda

I was once asked if the bermuda triangle is real, not knowing the answer I told them that I would find out for them! So, is the bermuda triangle real or just a myth?

--Kkeene06 16:45, 16 November 2005 (UTC)Keene-MindKkeene06 16:45, 16 November 2005 (UTC)--

Look at Bermuda Triangle. --Kainaw (talk) 16:51, 16 November 2005 (UTC)
  • The area is real and there's enough real reports of people going missing in the area. However, the reason of these disappearances is still not known for sure. - Mgm|(talk) 18:58, 16 November 2005 (UTC)

The best explanation I heard for the disappearance of so many ships in this area is that the continental shelf off the coast of America contains a lot of methane gas which is frozen due to the pressure in the deep ocean. The shelf is not hugely steep and if there is an underwater land slide this methane is released as a kind of big Jacuzzi, like swamp gas. (ever stuck a stick in the bottom of a muddy pond and seen bubbles rise up?) Ships cannot float on water full of bubbles and they sink. Others catch fire and sink if the gas is ignited by the ships boilers/electrics. It’s all very local and all very quick. This might explain some of the strange disappearances but not all and I might add that this is just what I read somewhere as a possible explanation for some of the disappearances.--Eye 23:13, 16 November 2005 (UTC)

According to the Bermuda Triangle article, there is no justification for claiming that the Bermuda Triangle has a higher rate of lost ships/planes than anywhere else over the ocean. Basically, you can claim there's a nasty area south of Hawaii and give it a cool name. Then, go through history and claim every ship/plane that went down there was lost due some mysterious force. --Kainaw (talk) 23:46, 16 November 2005 (UTC)

[edit] How Curcumin is Made From Tumeric

Please describe the chenical process by which curcumin is extracted from tumeric. What percent of tumeric yields curcumin?

Neither turmeric or curcumin explained those two specific facts, but between them they have enough links and references you could probably find it. And googling for "curcumin extraction" found this among the first few links that explains how to do it. - Taxman Talk 13:56, 17 November 2005 (UTC)

[edit] Static Electricity on Dry Nights

I notice I get shocked more around the house on dry nights. Why is that? - Cobra Ky (talk, contribs) 19:45, 16 November 2005 (UTC)

Dry air is a great insulator. It inhibits electrical flow. So, in dry air, the surface electricity on your body (and on other things) doesn't leak into the air easily. Eventually, the buildup will be enough that a spark can jump a small gap. --Kainaw (talk) 19:51, 16 November 2005 (UTC)
It's nothing to do with the conductivity of air. To quote Mr Static, "The effect of increased air humidity is to increase the thickness of the moisture layer on or in all surfaces, and this layer contains electrolytic ions that provide neutralizing charges." --Heron 17:11, 19 November 2005 (UTC)

[edit] November 17

[edit] How much annual precipitation does a tropical rain forest receive?

Is this a homework question? If so, the answer lies within the question. --hydnjo talk 01:43, 17 November 2005 (UTC)

[edit] what is the scientific name for a boa constrictor?

According to Boa, it's Boidae Boa. -- SCZenz 01:13, 17 November 2005 (UTC)

A Latin binomial such as Homo sapiens consists of the genus and the species names. Homo is the genus to which we, humanity, belong (along with Homo erectus, Homo floresiensis - all of which are extinct) and sapiens is the specific species name. Boidae is the family which includes several genera, one of which is Boa. In short, the Latin binomial for Boa constrictor (eg. [genus] [species]) is, anticlimactically, Boa constrictor. --Oldak Quill 17:10, 17 November 2005 (UTC)

[edit] Animals!!!

What type of animal is Scorpion!? —Preceding unsigned comment added by 67.70.39.83 (talk • contribs)

According to Scorpion, it's an arachnid, just like a spider. -- SCZenz 01:14, 17 November 2005 (UTC)

[edit] Cows

How many organs cow have (stomach) —Preceding unsigned comment added by 67.70.39.83 (talk • contribs)

It's got four stomachs. Past that, take a look at cow. -- SCZenz 01:31, 17 November 2005 (UTC)

[edit] Black holes

Is BLACK HOLE real? Can it like kill someone? If black hole sucks you in where are you going to be??? —Preceding unsigned comment added by 67.70.39.83 (talk • contribs)

In order: very probably, yes, and squished to nothingness in the middle. For more info, see black hole. -- SCZenz 01:30, 17 November 2005 (UTC)
I keep thinking that the experience of crossing the event horizon (without being spaghettified or incinerated by the orbiting matter) would take an extraodinarily long time, seeing as how you'd be approaching the speed of light fairly rapidly. (tangentially, would it compress time enough for basic particles to decay before they reached the "center"?) Or have I got relativity backwards? Tzarius 06:23, 17 November 2005 (UTC)
It would take a long time (in fact, forever) from an outsider's perspective. From the perspective of someone falling in it would be very, very fast—a few seconds for all but the most enormous black holes. -- SCZenz 06:36, 17 November 2005 (UTC)
Oh dear, there's that again. I wanted to read up on the subject before pursuing this any further, but now that it has come up again... Doens't a black hole also compress space? In other words, isn't there a large (infinite?) amount of space inside a black hole, which, from the outsider's perspective, is little more than a point? Mass makes a dent in space. A huge mass could thus stretch this into something big enough to hold a universe of its own. Right? DirkvdM 10:01, 17 November 2005 (UTC)
No, I don't think that's true. I know the pictures show space appearing stretched, and going "infinitely far down" for a black hole, but that's not what's meant to be conveyed by the analogy of gravity as curved space. The distances inside appear rather finite when you're falling in. -- SCZenz 22:37, 17 November 2005 (UTC)
However, the closest known black hole to earth is apparently 1600-odd light years away. Given that the furthest a human has travelled from earth is about one light-second, and the furthest an unmanned probe has travelled is less than fourteen light-hours away, we're not likely to get anywhere near the thing in your or my lifetime. --Robert Merkel 22:55, 17 November 2005 (UTC)
But that's the closest known black hole. A problem with black holes is that they're black, which makes then a bit hard to see. :) Of course there are ways to detect them, but the known ones are probably a minute fraction of the existing ones (are there any estimates on that?). If one were to approach the Sun that would probably be the end of us. What the chances are is probably little more than a wild guess, but if it were a frequent phenomenon then we'd see that happening all over the universe (which we don't?), so I'd agree that you can count on it not happening in our lifetimes. DirkvdM 08:42, 18 November 2005 (UTC)
Neutron Star by Larry Niven suggested that the tidal effects (difference between gravitation on your closest and nearest points) meant that a close approach to a neutron star would be fatal. I suspect the same must apply to black holes, so that there can be no way a living human can pass through the event horizon. (But if one could, could he take a string telephone?) Notinasnaid 09:44, 18 November 2005 (UTC)

[edit] size of a lymphocyte

It says that a lymphocyte's nucleus is about 7 micrometers in diameter. What is the size of the rest of it? What is the ration between the cytoplasm and the actual nucleus? And what are the other parts to a lymphocyte besides its nucleus?

Circulating lymphocytes usually have a nucleus that fits in that range. Most have only a thin rim of cytoplasm around their nucleus, so the cells as a whole tend to be not much larger than about 8µm or so. (Activated lymphocytes are considerably larger, up to twice that [around 15-18µm], but I suspect you're talking mainly about circulating lymphocytes.) Despite its small size, the cytoplasm does contain organelles, including endoplasmic reticulum, a small Golgi apparatus, mitochondria, and lysosomes. Hope that helps. --David Iberri 14:54, 17 November 2005 (UTC)

[edit] Scince

What are the differences and similarities between a conventional camera and a digital camera? Please explain to me by words and by Venn diagram. Thank you!--67.70.39.83 02:26, 17 November 2005 (UTC)

Please do your own homework. The articles camera, digital camera, and Venn diagram should help. --Kainaw (talk) 02:28, 17 November 2005 (UTC)
What's a "Scince"? And, thanks for signing your own stuff. --hydnjo talk 02:31, 17 November 2005 (UTC)

I ment Science =)

[edit] Venn

Hmmm... What is Venn diagram and how it works?--67.70.39.83 02:33, 17 November 2005 (UTC)

See Venn diagram --HappyCamper 02:37, 17 November 2005 (UTC)
(Hey HC, edit conflict) Please read Venn diagram and then if you are in need of help well then ... c'mon back. --hydnjo talk 02:47, 17 November 2005 (UTC)

Can you explain it to me in your own words?

What part of the article would you like us to clarify for you?--HappyCamper 03:48, 17 November 2005 (UTC)

OK, for example i have two candys, both candies have similarities (like taste) and differences (like shape) so how do I draw Venn diagram about this two candys?--67.70.39.83 04:18, 17 November 2005 (UTC)

Draw two big circles that overlap a bit. (The images at Venn diagram should illustrate this.) Label one circle with the name of one kind of candy (suppose it's "candy A"), and the other circle with the other kind of candy ("candy B").

Write things that are similar between candy A and candy B in the middle section (the intersection of the two circles). Differences should go in the rest of the circle. For example, if candy A is square and candy B is round, you would write "square" in the "candy A" circle, and "round" in the "candy B" circle.

I hope this helps. The Venn diagram article is terribly written, so I don't blame you for not understanding it. rspeer 04:29, 17 November 2005 (UTC)

[edit] heat transfer

Pour hot water in a glass with a silver spoon in it:

a)why will the spoon get hot?
b)why will the glass heat up?
c)why does the glass break when the water is too hot? —Preceding unsigned comment added by 203.84.189.18 (talk • contribs)
Did you make this question up or did your teacher? DYOH. Read the Heat article and then if you need help well then c'mon back. --hydnjo talk 03:27, 17 November 2005 (UTC)

[edit] Ebola Virus

Which cells does the Ebola Virus attack. Also I need info on the genetic make up.

Try Ebola? —Keenan Pepper 12:06, 17 November 2005 (UTC)

[edit] Sugar High

What exactly is a Sugar High if there is such a thing. What is the biology behind it. Doing this for my bio coarse.

See Sugar#Sugar and hyperactivity. "Sugar high" is widely regarded as a myth; high blood sugar doesn't make you hyperactive, it just makes you lose your appetite. —Keenan Pepper 12:11, 17 November 2005 (UTC)


A Sugar High is a concept of American folk biology. The concept is that excessive sugar will somehow make someone either "intoxicated" (e.g., Twinkie defense) to the point of diminished judgement or responsibility, or in its milder forms, euphoric. Either response of course, puts sugar in the cultural Bad Food category. The first concept is nonsense and the second perhaps has a nidus of scientific fact in the middle of the cultural concretion.

In terms of verifiable science, there are perhaps two relevant phenomena. First, sucrose tastes good, and this taste sensation is strong enough that studies have shown it can be used as an analgesic in infants-- this is part of the basis of the euphoria concept. Second, it is possible to show in animals that high or low dietary carbohydrate intakes produce somewhat differing effects on level of arousal of the autonomic nervous system. Unfortunately for the Sugar High meme, however, the effect of carbohydrates is generally sedating rather than arousing. alteripse 12:21, 17 November 2005 (UTC)

Though note that the Twinkie defence wasn't that excess junk can diminish ones judgement, it was that consuming excess junk can be a good indicator of judgement alread having been diminished. Unfortunately, it got seized on as arguing the former, which probably helped fuel the myth... Shimgray | talk | 12:21, 18 November 2005 (UTC)
I have never heard this interpretation. If you think about it for a moment it is actually lamer than the popular one-- which of the following is the correctly unpacked version?:
  1. It's not that this Twinkie on this day made him temporarily unable to tell right from wrong or control his impulses, but that too many twinkies on too many days made him more permanently unable to tell right from wrong or control his impulses;
  2. It's not that this Twinkie on this day made him temporarily unable to tell right from wrong or control his impulses, but that eating Twinkies is itself prima facie evidence of a mind so incompetent that he was unable to tell right from wrong or control his impulses.

And which is the lamer defense? alteripse 12:54, 18 November 2005 (UTC)

It's what our article on the Twinkie defense says... or rather, the original "twinkie defense" was that the consumption was an indication of a disturbed state, but now the usage of the phrase is to mean "junk food makes bad" as you mention. Apologies for being unclear, but I read it as referring to the original case rather than the general concept of a "twinkie defense".
In the original situation, basically, eating twinkies is not itself a sign of being screwy. Eating lots of twinkies and coke, when you've spent x many years eating good healthy salads and never touching junkfood, is possibly a sign (in context with other factors) that there's something up - imagine meeting a friend, who dressed very smartly as long as you can remember, to find they're unwashed, with tangled dirty hair, a ragged shirt and patched jeans. Not in and of itself an indication of a mental disorder, but a plausible outward manifestation of one, and not unreasonable as something to mention as corroboration if you're already arguing he had an undiagnosed disorder.
The problem is that "he was silly in the head and went shootin'" is pretty hard to reconcile with the case as it is presented - in the light of the case, it's a pretty lame defence - but verdicts of diminished responsibility through insanity are not uncommon, and this was just one where people could seize on something as "the loophole". Snopes has a decent writeup linked from the article. Shimgray | talk | 23:44, 18 November 2005 (UTC)
Golly, Shimgray, I could almost imagine how a guy in a three-piece explaining it like that mighta sorta coulda been taken seriously. You have a future in litigation! alteripse 00:17, 19 November 2005 (UTC)
I suspect the doctor in question believed there had been some kind of undiagnosed mental issues (to be fair, premeditated murder almost always means some!) and was casting around for evidence to support this. And in those circumstances, hearing of a major change in behaviour, especially one logically inconsistent with past behaviour, would presumably be a godsend. Reading the sfchronicle link, it notes that they brought up that White cast aside his normal habits and grew slovenly, quit working, shunned his wife, grew a stubble beard and rather than eat his healthful diet, indulged in Twinkies and Coke... - pretty notable changes for any individual, and taken together...
It does seem that one defense attorney made the connection in a vague aside about the modern "sugar rush" concept - Whether or not ingestion of food stuffs with preservatives and sugar in high content causes you to alter your personality somehow, or causes you to act in an aggressive manner, I don't know. I'm not going to suggest to you for a minute that that occurs. But there is a minority opinion in psychiatric fields that there is some connection... - but he certainly didn't intend it to be his actual case; it was more something he'd heard vaguely, thrown in because, hey, you probably can't have enough little details to support diminished-capacity. Shimgray | talk | 00:41, 19 November 2005 (UTC)

[edit] How to know if an Octopus a male or female?

I am doing research for my little daughter on the above topic. After a long time for search but still got no answer. Could you help on this? Thanks a lot. Mike Wong in HK.

It may depend on what kind of octopus you're thinking of, of course. But this post from the biology blog Pharyngula, suggests that even the octopuses themselves would have a hard time answering your question: "These octopuses seem to be able to recognize that the other is a conspecific, but do not recognize whether the other is male or female, at least not until after they begin copulation. Put two octopuses together, and within 3-4 minutes, a male will have pounced on the other, whether it is male or female, and inserted his hectocotyl arm into it's mantle. There didn't seem to be much in the way of perceptible preliminaries. Once copulation began, the male would figure out whether he was having sex with a male or a female." David Sneek 08:15, 17 November 2005 (UTC)
The short answer is that, in general, male octopuses are distinguished by a modified third arm, called a hectocotylus, that is used in mating. More detailed information can be found at the Cephalopod Research website here and at The Octopus News Magazine Online here. --DannyZ 03:11, 18 November 2005 (UTC)

[edit] Identifying Bacillus bacteria

Dear Wikipeida, I am a medical laboratory science student. I was identiftying this unknown bacteria of Bacillus thuringiensis. I incorrectly identified it as Bacillus cereus, a very close relative of my unknown organism? I was wondering if anyone from this Wikipedia site knew any major birochemical, cellular, or any differences between the two species which would aid in an identification between the two speicies. Any insight would be great, thanks.

Well, a bacteriology manual would be a better place to look for this information. But.... B. anthraxis can be distinguished from other bacillus species because it has a capsule (and also, hopefully, by the fact that no one will be giving it to you as an unknown). Bacillus thuringiensis is distinguished from B. cereus and B. anthraxis by being pathogenic for lepidopteran insects (moths), and by producing an intracellular parasporal crystal in the process of sporulation. As you probably know, nomenclature of microorganisms frequently changes, and these organisms are so closely related that some would place two (B. thuringiensis and B. cereus) or all three in one species. I'm a little surprised that you'd be tested on distinguishing B. thuringiensis from B. cereus: presumably you're not expected to perform DNA sequencing. "Bacillus species" has usually been close enough for most microbiology labs that I know of. - Nunh-huh 02:51, 19 November 2005 (UTC) You may find this .pdf file of interest. At least under the proposed UK guidelines, standard operating procedure distinguishes three classes: B. anthraxis, B. mycoides, or B. cereus or B. thuringiensis. It doesn't try to distinguish cereus and thuringiensis. - Nunh-huh 02:56, 19 November 2005 (UTC)

[edit] chemistry

who is calld the king of all chemicals and what is its formula

Hmm, a Google search turns up only one result, which says it's love. That sounds good enough to me. =P —Keenan Pepper 12:16, 17 November 2005 (UTC)
Excellent answer to a question I didn't expect anyone to answer. Rock on! --Avijja 07:16, 18 November 2005 (UTC)

[edit] Could Chernobyle have been "Sabotage" ?

Could this attached story be a "factor" or "cause" to the "Chernobyl accident " ?

Regards,

The Toxic Reverend Radiation Expirements on Humans http://www.angelfire.com/nm/redcollarcrime/radia.html


CIA slipped bugs to Soviets Memoir recounts Cold War technological sabotage By David E. Hoffman

The Washington Post http://www.washingtonpost.com/wp-srv/front.htm Updated: 12:13 a.m. ET Feb. 27, 2004

News article removed, view it at the following URL: http://www.msnbc.msn.com/id/4394002/

Um, the contents of the Reference Desk are GFDL just like any other page, right? —Keenan Pepper 12:44, 17 November 2005 (UTC)
I've removed the text of the news article as a copyvio. The original poster claimed a fair use rationale, but wikipedia guidelines say that in general, extensive quotation of copyrighted news materials... is not fair use. The article is still available at the URL linked above. —David Wahler (talk) 13:03, 17 November 2005 (UTC)
To answer the question, read our article on Chernobyl. Research points to flaws in personnel procedures as well as overall reactor design rather than point-failure of components. Given that, it's impossible to hang a sabotage label, and unlikely that tainted industrial contributions from the US would have had any meaningful effect. — Lomn | Talk / RfC 15:30, 17 November 2005 (UTC)
FWIW, I don't think so. For one thing, Chernobyl was of a completely different design to any American reactor, so there was little point in stealing American reactor control code except as something to learn from, rather than copy directly. Secondly, the alleged sabotage supposedly related to oil pipeline control code, not reactor control code. Thirdly, I have my doubts about the sabotage story for that oil pipelines. I do research into software testing; the story of how the sabotage caused spectacular but casualty-free damage in such a precise manner after the Russians had configured and modified the software for their own uses is just a tad too cute to be believable. Fourthly, the sabotage theories do not square with any of the Soviet inquiries into Chernobyl; sure, they were conducted in Soviet times, but as I understand it no new evidence has emerged to suggest a massive cover-up. Finally, the idea that America would sabotage a Russian nuclear reactor makes no sense. It's not like Chernobyl was producing anything that the Russians didn't already have in quantities sufficient to wipe most of the West off the map (heck, they still do). Imagine that the US had been caught doing so, killing a bunch of civilian reactor workers and potentially thousands of Russian (and even Western European) citizens. It would have completely fractured NATO (and other friendly countries around the world like Japan and Australia). Heck, the Russians might just have gotten mad enough to start a war over such an act; probably not, but there'd be a real risk. And for what payoff? Destablizing the man whose reforms, even then, looked like the best chance for a better relationship between East and West since the Cold War began? So, no, I don't think this conspiracy theory makes sense. And when similar suggestions were made on the article's talk page, I asked the Russian Wikipedians to comment. They thought it was complete nonsense also. --Robert Merkel 23:22, 17 November 2005 (UTC)
Agreed. Just another wacky conspiracy theory. An as the saying goes "fantastic theories require fantastic evidence". StuRat 23:00, 22 November 2005 (UTC)

[edit] willies

how long is the longest willy in the world?, send your answer to [email removed] as soon as possible please. thankyou for your dedication.

We have an entire article on human penis size. This is also the first entry at world-sex-records.com. —Keenan Pepper 12:20, 17 November 2005 (UTC)
More specifically [45]. --R.Koot 12:23, 17 November 2005 (UTC)
Why do you guys instantly think penis? Is this freudian? :) Willie and Willy are also names, so maybe the asker wants to know the who the longest person named Willie is. And 'willie willie' is also Aussie lingo for a miniature whirlwind (so how big can those get?). Then again, I suppose you've probably understood him correctly.... DirkvdM 09:27, 18 November 2005 (UTC)
Looked it up. The

Why restrict the answer to humans only, who are rather pint-sized when compared to some other mammals. "hippopotamus and elephant can be several feet in length" and in " large Rorqual whales the penis can be 10 ft. long". [46] BlankVerse 14:39, 18 November 2005 (UTC)

Women are preoccupied with large willies and men preoccupied with small vaginas, isn't life full of problems. :-) --Eye 21:19, 18 November 2005 (UTC)

[edit] Microsoft Excel cell fillup

I want to fillup empty Excel data cells smartly. Let's say I have a table like this:

John     Murder
         Rape
         Arson
Jack     Extortion
         Armed robbery
Sally    Mass killing
         Driveby shooting
Tom      Jaywalking
         Murder

(10,000 bad guys and 100,000 crimes in total ...)

If I select John and let Excel fills it up downwards, it'll become:

John     Murder
John     Rape
John     Arson
John     Extortion
John     Armed robbery
John     Mass killing
John     Driveby shooting
John     Jaywalking
John     Murder

This is not what I need. I need John-John-John-Jack-Jack-Sally-Sally-Tom-Tom. How do I do this. It'll be painful to do that manually. -- Toytoy 10:14, 17 November 2005 (UTC)

I don't know of a built-in method, but a fairly simple Visual Basic macro to do it could something like:
Dim i
Sub wiki_list()
For i = 1 To X ' Change X to the number of entries in the list (including column title)
    Range("A" & i).Select
    If Selection.Value = "" Then
    ActiveSheet.Paste
    Else: Selection.Copy
    End If
    Next i
End Sub
Change the X to the exact number of fields you wanted filled. If you haven't used a macro, simply click 'Tools', select 'Macro' and 'Macros'. Type a word into the top box that appears, and click 'create'. Then paste the following at the top of the text editor that appears. Then, hit the play button on the toolbar at the top. (Note: You cannot undo macros, so save the list first, in case it goes wrong). If anyone can do it any better, please say how! smurrayinchester(User), (Talk) 15:29, 17 November 2005 (UTC)
Here's a way to do it without macros. Let's say your list of names is in column A, and the crimes are in column B.
  • Create a new column between the two by highlighting a cell in column B and choosing Insert - Column. The new column is column B and the crimes are now in column C.
  • Copy the first name in the list from A1 to B1.
  • in cell B2, enter the following formula: =IF(A2="",B1,A2) (in English, this means, if the cell to the left of this one is blank, copy what's in the cell above this one; if not, copy what's in the cell to the left.)
  • Highlight B2 and drag the lower right corner to copy that formula into the rest of the cells in column B.
  • Optional: if you need everything back in the original columns, highlight column B, choose Edit - Copy, then (with column B still highlighted) Edit - Paste Special. In the Paste Special dialog box, click the "Values" option, then click OK. Then, right-click on a cell in column A, choose Delete... and then choose the "Entire Column" option and click OK.
Chuck 18:57, 17 November 2005 (UTC)

[edit] Another macroless option

  1. Highlight all the values in the column including the blanks
  2. From the Edit menu, choose Go To . . .
  3. Click Special
  4. Click on Blanks
  5. Click OK
  6. Type =
  7. Click on the cell above the first blank cell
  8. Press Ctrl + Enter (simultaneously)

Nelson Ricardo 00:41, 18 November 2005 (UTC)

[edit] Understanding Eye Movement Patterns - does the human eye commonly move in a "flipped" number 6 motion?

I am trying to relocate a piece of information that I recall reading years ago. It was an article / study that tracked how our eyes commonly move when we are confronted with new information - such as a new package, a new magazine cover, a billboard, a print ad, etc. I seem to remember that the researchers discovered that our eyes commonly move in what I would call a flipped number 6. (Sorry, i am bad a trying to describe spatial stuff - so bear with me) the pattern described was as if the eye were writing a backward "6" - starting at the upper left of the picture, and scanning right and down, and looping back up and to the left - ending at about the center of the item. Can anyone help me validate this? I have tried the following searches - and again - I am a first time user, so I may not be searching effectively: tracking eye movement / how does the eye move when confronted with new information / how does the eye scan a page / etc - and I have had no success so far.

Thank you very much in advance for helping me with this.

CMT--61.213.181.82 10:45, 17 November 2005 (UTC) (is that the correct way to sign? Thanks for tolerating a first time user!)

The term you're looking for is Eye tracking, here are some related links that I'll add to the article:

The first document features something that vaguely looks like an inverted "6". However, it's important to note that the path that the eye takes varies quite a bit depending on what it's looking at. For example, my eyes automatically seek the upper, left-hand corner of an English document; but when confronted with Hebrew, they go to the upper right without any conscious thought on my part. When looking at artwork, my eyes tend to seek out areas of the highest contrast first and then follow contours. These trackers are very useful for determining what people notice in an advertisement, which things are distracting, and which elements are overlooked. Lastly, you did a great job asking the question. Cheers! --Avijja 07:57, 18 November 2005 (UTC)
See also saccade, which describes the track of the eye as more zig-zag in nature. --Ancheta Wis 15:21, 19 November 2005 (UTC)

[edit] Raise in temperature of a road tankers contents whilst in the sun

Is there an equation to compare the effectiveness of insulation for a stainless steel road tanker?

I wish to compare a insulated tank to an un-insulated tank.

Some facts and figures:

The uninsulated tank is cylindrical, 9 metres in length and 2 metres diameter and has a external surface area of 69m² The tank is constructed from 3mm thick 304 grade stainless steel which has a thermal conductivity, k, of 16.2W/m.°C There is 30,000kgs of liquid product inside the tank with a specific heat capacity of 3.9kJ/kg.°C

The product temperature is 5°C, the ambient temperature is 25°C

What will be the rate of temperature increase for the product in the uninsulated tank?

The insulated tank is the same tank as above but is insulated with a 70mm thick polystyrene external layer surrounded by a 0.7mm thick stainless steel cladding panels.

The polystyrene has a thermal conductivity, k, of 0.038W/m.°C

What will be the rate of temperature increase for the product in the insulated tank? 213.218.255.233 14:14, 17 November 2005 (UTC)

There is some missing info. The difference in temps between the inside and outside is critical, as is the amount of sunlight hitting the tanker and it's reflectivity. The wind, humidity, and air pressure would also play a role, as would any precipitation. If both temps are equal and it is night and there is no precip, then there should be no temp change in either case. Given the limited info you have, I would just say the ratio between the two rates of temp change would be approximately [(16.2W/m)/(0.003m)] / [(0.038W/m)/(0.07m)], if we ignore the thin layer of stainless steel on the insulated tanker. StuRat 16:47, 19 November 2005 (UTC)

[edit] Programming a gas furnace thermostat for max efficiency.

Is it better to set the temperature low when the house is unoccupied? The furnace then runs longer to raise it to a comfortable temp. when programmed to come on. Or is it better to maintain a more moderate temp. with the furnace only coming on periodically to maintain it? Also, does it use much more gas to maintain it at 70 degrees F as opposed to 65 degrees? (Note: Thermostat has available 4 changes for Mon - Fri and two for Sat-Sun)

Would apreciate comments 15:07, 17 November 2005 (UTC)~--4.225.202.248 15:07, 17 November 2005 (UTC)

A climate-control system is more efficient when the target temperature is closer to the ambient temperature (that is, a house at 80 F when it's 30 F outside cools much faster, and so requires more energy to maintain, than a house at 70 F in the same conditions). Consequently, it's better to set the thermostat low when unoccupied. Similarly, it's better to set the thermostat high in the summer to avoid unnecessary air conditioner use. — Lomn | Talk / RfC 15:33, 17 November 2005 (UTC)
Agreed. Turn the temp down to the lowest level you can stand, in winter, to save energy. One common misperception is that a furnace that is on longer is less efficient. This is true for some variable speed engines, such as a car engine, which are less efficient when running full-out. However, a gas furnace only runs at one speed and one efficiency. In fact, running it once for a long period is actually more efficent than many short runs, since there is some inefficiency associated with poor convection during start-up and running the fan after shut-down. There are some other concerns with turning the temp low when you are gone, however:
  • The pipes could freeze if it gets too low, especially pipes in exterior walls, such as those to outside faucets. Ideally, those pipes should be drained in winter.
  • Low temps could be uncomfortable for some pets, like dogs, and dangerous for others, like birds or tropical fish. Measures such as a warm dog bed or heated fish tank could fix these problems.
  • Temp variations, and the associated humidity variations, can be hard on wooden furniture. If your home is full of expensive antiques, keep the temp constant. If you have cheap furniture, don't worry about it, it will likely go out of style before it splits or warps. StuRat 16:34, 19 November 2005 (UTC)

[edit] The flooding k's

Could there be any sensible reason why my computer occasionally starts flooding letter k's wherever the pointer happens to be? Usually it happens when I haven't touched the keyboard for, say, 15 seconds. It looks very natural and human in that it keeps short pauses and sometimes slows down. It's quite nasty when trying to formulate the next sentence in my head. The keyboard is a USB one and the OS is Debian. Thanks! –Mysid 16:25, 17 November 2005 (UTC)

I'd suggest there's a broken wire. You need one of these to fix it. Alphax τεχ 07:40, 18 November 2005 (UTC)
It could be a broken or incompatible keyboard. It might be a malfunctioning or incompatible USB hub, dongle or port. It might be an old kernel or USB subsystem that doesn't work properly with your keyboard. Unless you're using a common USB device and running a modern Linux kernel, you are liable to encounter problems. Try connecting your keyboard directly to different ports on the motherboard. Try unplugging the USB keyboard and use a PS2 keyboard. Try just leaving the keyboard unplugged and see if it's still happening. I seriously doubt that this is caused by a keylogger, because those are designed to be quiet, and this isn't. PS: Alphax, that wasn't funny or helpful. --Avijja 08:23, 18 November 2005 (UTC)

[edit] Familial Alzheimer Disease / Mutation

I would like to know if Familial Alzheimer disease is a spontaneous mutation, and if so what fixes the mutant allele in the population? I read a research article that refered to the allele as a "private mutation", occuring only in idividual families excluding non relatives. Is a private mutation the same as a spontaneous mutation.--131.204.83.180 17:40, 17 November 2005 (UTC)

Our article on Familial Alzheimer disease should anwser your question. The condition is inhereted in an autosomal dominant pattern, which means that only one parent needs to have an inhereted or spontaneously mutated gene associated with FAD for the condition to be passed on, thus with about ~50% chance of the offspring getting a mutant copy of the gene, the disease then has a pretty good chance of becoming fixed in the population. I haven't come across the term "private mutation" before, but often papers focus on a particular family and this term might be being applied to the specific muation in one of the FAD associated genes common in that family.--nixie 03:39, 18 November 2005 (UTC)

"Private mutation" is a sort-of unfortunate term. It means, essentially, "observed only in one family" - or in this case, "the correlation between this mutation and Alzheimer's is observed only in this one family". It gets stretched sometimes to "only in a few families". It's mostly used to indicate that there's no reason to use the test for screening a general population. Alzheimer's can be caused by any number of mutations, in several different genes on several different chromosomes. All mutations are spontaneous, but if it's familial the original spontaneous mutation is being transmitted genetically in the usual manner - it's not re-occurring. A mutant allele will persist in the population until it dies out by being selected against, or by chance. - Nunh-huh 08:11, 19 November 2005 (UTC)

[edit] nanotechnology

what is the role of a chemical engineer in nanotechnology.

Nanotech, as you probably know, is the science of making REALLY small things. A chemical engineer working for nanotech, therefore, focuses on making very small but useful molecules. Examples include carbon rods and "buckyballs", or buckminsterfullerene. These molecules can be used to help develop nanorobots, as the structures developed lend strength to the tiny machines.

User:Articuno1

[edit] Groaning Islands

Robert Harris's novel Archangel mentions ferries from Archangel in Russia to a) Murmansk; and b) "the Groaning Islands". I've heard of Murmansk, but Google shows no trace of the Groaning Islands. Are they real? Mark1 19:43, 17 November 2005 (UTC)

Do you know the names of nearby landmarks, regions or relative directions? Did the author provide the Russian name? I used a detailed map and looked for islands whose Russian names might match along the coast from Arkhangelsk to Murmansk to Norway -- nada. I didn't have any luck with any of the Russian-language searches I tried. There are a baffling number of islands in the area, but only a few are named on the map. Many islands there served as forced labor camps, so it's possible that this was an unofficial name that reflects their gruesome history. If this was an official name, it's likely that they've since been renamed to something more pleasant. Oh well. On tangential note, I had fun looking at the map and was amazed by the bizarre names of the area's landmarks. I've translated some of them back into English for your amusement: "Ninth", "Little-Granny's-Hut", "Rounded", "Petro(leum)-Factory", "Semi-Islandish", "Fix-Up", "White-Mustache", "Big-Shelf", "Wolfy", "Third-Stream", and the mysterious "Giant-Western-Face". --Avijja 10:15, 18 November 2005 (UTC)
 ;) My only clue is that I found a map on the net (though I can't find it again) which showed one ferry route going west to Murmansk, and another east off the edge of the map. So maybe somewhere along the coast in that direction? Mark1 14:28, 18 November 2005 (UTC)
I looked in the other direction all the way to Hokkaido, Japan. Once past the Nenets Okrug, the map was basically blank and unsettled for thousands of kilometers and only the huge islands had names, and none of those matched. Taymyria (population density: 1 person every 22 km^2) had a countless number of unlabeled islands. Unless someone else has a better idea, I'm afraid these islands are going to remain clandestine a bit longer. --Avijja 21:52, 18 November 2005 (UTC)
Ah well, thanks for trying! Mark1 00:11, 19 November 2005 (UTC)

Could it be due to the groaning of shifting sea ice around these islands? --Eye 21:22, 18 November 2005 (UTC)

[edit] gallbladder

If the function of a gallbladder is to store bile to be used to help digest fat, what happens to the digestion system after a gallbladder is removed? What breaks down the fat in foods after digested? When a person does have their gallbladder removed, do they tend to be heavier due to the fat content in their system? 150.176.244.119 20:55, 17 November 2005 (UTC)

Like you said, the gallbladder is just a reservoir for bile produced by the liver. Removal of the gallbladder (cholecystectomy) doesn't prevent bile from reaching the small intestine; without a gallbladder, bile is delivered from the liver directly to the duodenum. So folks without gallbladders are able to digest fats just about as well as folks with gallbladders. And the process is the same: bile emulsifies fats and enzymes from the pancreas digest them. Hope that helps, David Iberri (talk) 03:03, 18 November 2005 (UTC)
I suppose the gallbladder has a function, and that might be to release the bile when it is needed, when food passes by. So lack of the bladder could reduce the efficiency of the bile (too much when it isn't needed and therefore too little when it is). So I can imagine it would still increase the chances of obesity. DirkvdM 10:03, 18 November 2005 (UTC)
Actually, being obese increases the chances that your gallbladder will be removed. You'll have a hard time finding anything which demonstrates that it makes much of a difference to anyone whether they have a gallbladder or don't. - Nunh-huh 02:32, 19 November 2005 (UTC)
I should think an inability to digest fat would lead to weight loss, not gain, as those fats would pass thru the system unused. A negative would be diarrhea, which is also cause by fat binders like chitosan and undigestable fat substitutes, like olestra. StuRat 16:05, 19 November 2005 (UTC)
I'm kicking myself right now. Stupid! DirkvdM 12:24, 20 November 2005 (UTC)

All I know is after my gallbladder was removed... I gained a lot of weight... hubby purchased some 'bile salts' for me.. I lost 18 lbs in 2 weeks.. and still loosing! I'm not changing my diet either. deb

[edit] Atomic Theory of Matter

What is the theory of Matter? Can u summarize it for me please?

Reading our atom article would be a good place to start. -- SCZenz 23:19, 17 November 2005 (UTC)
Also see atomic theory. -- SCZenz 23:20, 17 November 2005 (UTC)

The basic idea is that ordinary matter is composed of isotopes of the elements in the periodic table and ions of those atoms. Note that this excludes matter in nuetron stars, black holes, and some other special cases. These atoms are in turn made of protons, nuetrons, and electrons, which are in turn composed of quarks, which are in turn made of strings, etc. StuRat 15:17, 19 November 2005 (UTC)

[edit] November 18

[edit] Where was typhoid fever first found??

See Typhoid fever. It is as old as mankind. --Kainaw (talk) 01:42, 18 November 2005 (UTC)

[edit] Molar concentraion of NaOH

How do you calculate the molar concentraion of 24.05 ml of NaOH poured into 25 ml of HCL? To help: the molar mass of NaOH is 40g/mol

See molar concentration and do your own homework. --Kainaw (talk) 01:44, 18 November 2005 (UTC)
I am trying! But I do not understand how! The thing is that I don't know how to change 24.05 ml of NaOH into moles.
There is something missing in your question...you need to know the concentration of that 24.05 mL of NaOH before you can proceed. Does your question sheet state what it is? If not, then assume a concentration of "X" and continue... --HappyCamper 01:49, 18 November 2005 (UTC)


[edit] What is cave diving?

Spelunking will probably help you. — Knowledge Seeker দ 04:51, 18 November 2005 (UTC)

Cave diving will help you even more. DJ Clayworth 21:38, 18 November 2005 (UTC)

[edit] Light - Photons

1. Is light a continuous stream of photons? If so, light traveling from a distant star must connect the observer with the past in a very real way. In other words, along that continuous stream of photons some photons actually belong to part of the stream that is thousands of years older than other parts of the stream. How can such a structure exist? This stream of photons not only crosses vast distances of space, but also of time -- yet it remains a single unified structure that can carry a continous stream of information. Gary O--65.66.151.189 04:06, 18 November 2005 (UTC)

Light is made of photons, yes. And yes, photons arriving now from other star systems left many years ago. As for how such a structure can exist, you might read electromagnetic wave, wave-particle duality, photon, light, or speed of light, depending on what you mean. -- SCZenz 04:13, 18 November 2005 (UTC)
Light travels in packets of energy called quanta. - Cobra Ky (talk, contribs) 04:15, 18 November 2005 (UTC)
And those quanta (a general term) are called photons, in the case of light. -- SCZenz 04:17, 18 November 2005 (UTC)
Keep in mind nothing exists now except you. This may be the basis of subjective reality. Just like light, sound travels in waves, and takes a certain amount of time to reach you from the source; just on a much larger time scale compared to light. And even the electrical signals of your firing synapses take a finite amount of time to traverse your brain, so even you might not exist in the now. - Cobra Ky (talk, contribs) 04:22, 18 November 2005 (UTC)
Oh yummy, that's a philosophically wonderfully confusing way of looking at things. I found the question a bit odd - how can one see the stream of light particles as a structure, as an entity. But if there is one entity one can be sure of it's the self (cogito ergo sum). But different parts of that self 'exist' at different moments in time. So what, then, is 'now'? If reality and therefore the 'now' is defined by me (in my case, that is) then there can't be different nows for me. Or do I exist in different nows at the same time? I'll have to sleep on this one. I feel a Zeno paradox coming up, but I don't want to go there right now (whenever that is). DirkvdM 10:36, 18 November 2005 (UTC)

Going back to the original question: think about a snapshot photograph of a stream of water coming from a water hose and that the stream is an entity of water molecules being emitted from that hose. The water molecules at the end of the stream furthest from the hose are older than the water molecules that have just come out of the hose. Now go to live action: watch as the hose is modulated (wiggled around) and watch that information travel in time to the end of the stream. I think that's the concept you are trying to capture. As always, analogies eventually fail so don't take this water stuff too far.  :-) --hydnjo talk 02:21, 19 November 2005 (UTC)

Let's see if we can unravel the question a bit further...:
  1. Is light a continuous stream of photons? - This is actually quite a difficult question to answer, because there are a number of concepts which are underlying this. I would say "no, not really...it does not have to be." - keep in mind that photons are really just a particular concept for light - a particular model which describes certain behaviours of light. In reality, we don't really "know" what light is, but we know from science and systematically repeatable experiments that it behaves sometimes like particles, sometimes like waves, and sometimes like a mixture of the two. It's perfectly okay to think of light in that manner, but it is slightly misleading, as it is subtlely mixing up the particle and wave models for light.
  1. ...If so, light traveling from a distant star must connect the observer with the past in a very real way.
Yes, I would agree, in some sense this is the case. If you look outside on a very dark night, you are in some sense, looking at some sources of light that has travelled millions of years to you! You are literally "looking back in time!".
Your comment "...This stream of photons not only crosses vast distances of space, but also of time -- yet it remains a single unified structure that can carry a continous stream of information...." -- You can think of it this way: Light is a form of energy, and in its purest form, there is nothing more to light than light itself... so in some sense there is some unity behind all this. However, I would not overextend these ideas. There is much beauty out there between physics and philosophy, and is always a good idea to know which end of the continuum you are leaning on! Hope this helps :-) --HappyCamper 03:49, 19 November 2005 (UTC)

If light waves contain quantized particles that we call photons, why don't sound waves contain quantized particles as well? Why is it that light is special and not other types of waves? If the particles in my body and all around me emit matter waves, shouldn't there be a particulate component to all waves? - Joe S.

[edit] Hoff Lu's Equation of Irreversibility?

I came across this, but had no idea what it is. Google doesn't give much answers. Care to shed some light?

-- Миборовский U|T|C|E 07:38, 18 November 2005 (UTC)

[edit] keyboard shortcut for WindowsXP to create a new folder

I had been looking for the keyboard shortcut for WindowsXP to create a new folder for a very long time, but I still can't find one. does anyone know what it is? I'm sick of clicking the mouse and wait for the menu pop-up, just for creating a new folder.

thanks! guys!

Unless you're on the desktop, you can do Alt, F, W, [Enter]; alternatively, try Alt-D, Alt-F, [Enter], [Enter]. Neither is very elegant and probably not much faster than waiting for the right-click menu (which sometimes takes ages, doesn't it?). Plus, either may fail if your version of Windows is not in English. There is a program advertised at this website which claims to be able to give you a shortcut key to create a folder using VBScript, but I haven't tried it personally (see the discussion on annoyances.org), so use at your own risk. As far as I can tell, there is no built-in shortcut in Windows for creating a new folder (someone would have found it by now). Maybe in Windows Vista... Either way, Good luck! — QuantumEleven | (talk) 09:21, 18 November 2005 (UTC)
On a related note, if your context menu is taking forever to load when you right-click, you can download some freeware (snapfiles.com) called "ShellExView" which lets you view and enable/disable shell extensions installed on your system. Disable enough of them that you never use anyway, and your right-click menu should start appearing much more quickly. --PeruvianLlama(spit) 10:23, 18 November 2005 (UTC)
OS X Whoops you: Command+Shift+N

[edit] Technology behind Submarines

What is the technology behind Modern Submarines? How do a submarine Sink and what does it do to come back to the surface of water? What kind of driving mechanism does it equip to steer sush a under water giant? Where does a submarine use nuclear tecnology? What will be the maximum speed of a submarine? Is there any time limit for a submarine to remain under water? What are the various components of a typical Submarine? --61.17.220.200 10:09, 18 November 2005 (UTC)

The Wikipedia article, Submarine would be a good place to start. Plus there are plenty of external links on that article. Also check out the howstuffworks article. - Akamad 10:48, 18 November 2005 (UTC)
With modern nuclear submarines, they can desalinate ocean water to make drinking water and produce oxygen by electrolysis. The nuclear power plant can operate for years. The physical limiting factor is then food for the crew. However, the isolation and separation from loved ones also creates a psychological limit. Perhaps having married couples on board would solve this problem, but would require more space to be devoted to "family crew compartments". Similar issues arise with long term space travel (with current technology, it takes years even to get to other planets in our own solar system). StuRat 15:05, 19 November 2005 (UTC)

[edit] whole cell simulation

what are virtual erythrocytes

  • An erythrocyte is a red blood cell. "Virtual" means you're talking about a blood cell simulated in a computer. - Mgm|(talk) 19:14, 18 November 2005 (UTC)

[edit] Ports question

I understand there is a command in Command Prompt to find out what ports your firewall is using/allowing. Can somebody tell me what this command is, and perhaps a little more detail on what to do? -Tim Rhymeless (Er...let's shimmy) 10:27, 18 November 2005 (UTC)

  • Assuming you're using windows, the command "netstat" will show you all the ports currently in use. Under XP, "netstat -b" will also display which applications are using which port. If you install a software firewall like Kerio or Zonealarm, you can get a friendly GUI view of the same info. --Bob Mellish 16:09, 18 November 2005 (UTC)
    You'll need to use netstat -a (or netstat -ab), or you'll only see existing connections, rather than what ports are being listened on. --Pidgeot (t) (c) (e) 19:14, 18 November 2005 (UTC)
Netstat isn't a msWindows thing. It also works on the Unix family of OS's (which includes Linux). Actually, that's probably where it came from, with the msWindows version being an imitation. DirkvdM 08:56, 19 November 2005 (UTC)

[edit] septic tanks and photographic processing

Can normal developing and priniting chemicals used in B & W photogrphy damage a septic tank sewage treatment system; if yes, is there any method of filtering the chemicals from the drainage?

A home septic system depends on robust anaerobic bacterial activity for its long term survival. My rule of thumb is can bacteria survive in this stuff? My quess is that it is your best interest to bottle it up for disposal elsewhere. --hydnjo talk 15:46, 18 November 2005 (UTC)

[edit] Polar "radiant"—?

On a globe, all meridians converge at the poles. If you wanted to express it the other way—the meridians emanate from the polar point—what would that polar point be called, the polar "radiant" (like with a meteor shower, the meteors appear to radiate from a single spot, which is called the radiant), or is there a better or more proper name?: See this image. ~Kaimbridge~ 15:51, 18 November 2005 (UTC)

In a meteor shower there is movement, so specifying a 'direction' (outward) makes sense. With meridians, that is not the case, so I wonder why you would want to use a different viewpoint and name. Put differently, they'd still be called 'poles'. What is the reason for your question? DirkvdM 09:02, 19 November 2005 (UTC)
Well, because I plan on discussing "transverse graticule", where the "pole" is on the equator (imagine the pole on this image is on the equator). I had thought the term may be "apex" or "vertex", but when its on the equator (or obliquely in between the equator and pole), those don't seem appropriate—the term I am looking for is meant to describe the meridians "sprouting" out of a single point (i.e., "radiating"), such as I tentatively have it now, in discussing the "transverse graticule's radiant". There very well may be a specific geometric (or other general math) term that names this idea that I either can't think of or haven't heard of. ~Kaimbridge~ 15:10, 19 November 2005 (UTC)
There is the movement of magnetic particles along the magnetic lines of force, which eminate or terminate at the magnetic north and south poles, resulting in auroras. StuRat 14:52, 19 November 2005 (UTC)
Magnetic particles? Never heard of those! I thought that the magentic lines were a projection to visualise magnetism. And therefore static. If they have a direction then they must have a speed also. Do they?
But back to the question. Failing the magnetic field, there is no direction, like I said. The opposite alternative to 'radiant' could be 'convergent' (or 'convergant'?). A more static word could be 'node'. Which sounds conveniently similar to 'pole'. DirkvdM 12:45, 20 November 2005 (UTC)
That was my term for particles affected by magnetism, which would be charged particles, including ions, free electrons, and free protons (unless you consider those to be hydrogen ions). Iron-containing particles would also be affected by magnetism, but I wouldn't expect any of them in the upper atmosphere. Also note that a photon carries the electromagnetic force, according to gauge boson theory, so could also be called a "magnetic particle". StuRat 07:14, 21 November 2005 (UTC)
Then how about "transverse vertex"? ~Kaimbridge~ 15:28, 20 November 2005 (UTC)

[edit] Commodore 64 Help

A Turkish user sent the following email to the Wikipedia help mailing list.

At my home I have a Commodore 64 which has been sitting in the cupboard for many year without any use. Just yesterday I wnted to install it and use it. However I forgot to use it.

I have some games on the cassette and I also installed all connections. After the installation the screen (TV) came as READY. I need to run one game on the cassette however I can not remember what I write and what command I have give the COMMODORE 64 for running the game programme.

Please kindly send me simple explanation for that.

Thanls for any help you can offer him or her.

Capitalistroadster 16:58, 18 November 2005 (UTC)

Going from memory, you type list to list files on tape or disk. Then, you type load "file",8,1 - but I can't remember what the ,8,1 is for. Those may not even be the correct numbers. --Kainaw (talk) 18:02, 18 November 2005 (UTC)
For disk games, you have two options. You can either try LOAD "*",8,1 to load the first program (usually works with official disks), or you can do LOAD "$",8,1, LIST, LOAD "PROGRAM NAME",8,1. Either way, type RUN after this to start the program.
For tapes, rewind the tape to the beginning, type LOAD, and press Play on the tape player. Once it finds the program, press the Commodore key. If you need to find a specific program, use LOAD "PROGRAM NAME" instead of just LOAD.
As for what ,8,1 means, it refers to the disk drive. Actually, older versions of the C64 might not recognise the ,1 part, if memory serves me correctly. --Pidgeot (t) (c) (e) 19:10, 18 November 2005 (UTC)
LOAD "filename",device number, 1
The device number for the tape drive, if I remember correctly, is 1. The default for the disk drive is 8 (and 9 for a second floppy disk drive). The final '1' specifies that the code loaded should be loaded into the same place in memory that it was saved from. This allows some programs to run automatically once loaded, without requiring the use of the RUN command.
If you use the LOAD command without a device number or trailing ,1 (that is, LOAD "filename"), the tape drive will be assumed. TenOfAllTrades(talk) 20:48, 18 November 2005 (UTC)

[edit] Drilling projects

What are three or four of the deepest drilling projects on record?

There is a list provided here, not too much detail though. Akamad 22:58, 18 November 2005 (UTC)

[edit] Prime Modular Fields

How do you prove: Zmod(n) is a fied if and only if n is prime?

Start by proving it has no zero divisors. That means it's an integral domain, and every finite integral domain is a field. —Keenan Pepper 20:27, 18 November 2005 (UTC)


[edit] Software Companies

Is there a cost implication or technical hurdle which prevents software companies adding multiplayer co-op modes to their first person shooter releases on the PC platform?  :)

Adding multi-player code to a game is a major undertaking that requires lots of time, planning and skilled programmers. However, once this code is written, it's easy to add the various multi-player modes, such as death-match, co-op, capture the flag, etc. I'm not sure why so few add co-op mode. --Avijja 09:55, 20 November 2005 (UTC)
I thought the big hurdle was how differently you have to make the singleplayer (campaign) portion of the game, to allow multiple players. IE in Serious Sam, it was planned from the beginning, so levels had respawn points and triggers didn't trap players behind doors and such. Whereas Half-Life 2 with its precarious balance of triggers, scripting and level changes, would require a complete redesign and would probably need to scrap half the puzzles because they wouldn't work in co-op play. Co-op is a blast though! Tzarius 23:21, 20 November 2005 (UTC)
  • Multiplayer games mean that the company has to run the servers. This can be time-consuming and expensive, compared to simply selling a CD which runs entirely on the user's machine
  • Multiplayer games require (a) lots of people playing, and (b) everyone to have a low-latency network connection. This can be solved in small areas with a LAN party
  • Multiplayer games mean that cheats need to be detected, and that peoples' computers can't be trusted to do calculations for fear that they might be modified to cheat, and sometimes peoples' computers can't even be trusted with data about the game. This makes network programming even more difficult than it already is
  • Multiplayer game purchasers often request new areas of game territory to explore, although this is more related to real-time strategy games than first-person shooters. See World of Warcraft for some of the problems this can cause.
Having said, that (a) Single-player games are just as difficult (because you need to make them interesting), and (b) many game libraries (such as Torque Game Engine) include multi-player modes by default. Ojw 19:45, 26 November 2005 (UTC)
Not every game developer runs (or needs) their own centralised servers, often the task of server list maintenance can be taken on by the likes of Gamespy. New content is not a problem for games that have publicy available content creation tools, such as map editors or SDKs. Also, not all games require low-latency connections. Tzarius 20:47, 26 November 2005 (UTC)

[edit] November 19

[edit] Fantastic

I am amazed how wikipedia functions. It seems infinetly filled with knowledge. How was this accomplished? vedam

That's the power of open source, which is the power of numbers. Anyone who wishes to contribute may do so. And on Wikipedia it's instant; you don't even need to log in, a barrier used on many other sites. Suppose the number of contributors corresponds to 1% of the population of the US (where most English language contributors will come from). That would be some 3 million. Suppose in the past year they have on average spent 1 hour per day working on Wikipedia. That's 3 million x 365 = roughly 1 billion hours. There are close to 1 million articles on the English Wikipedia (ranging from stubs to very extensive articles). So on average about 1000 hours will have been spent on each article. Of course this is a very rough calculation, but the point is that the numbers are just staggering.
Which is also the power of Linux. With 5 billion people on Earth there will always be a huge workforce of volunteers for Linux. So unless some other OS replaces it, Linux is here to stay (which can't be said for microsoft because they have to pay their employees and thus depend on revenues). The same goes for Wikipedia, but of course the number of potential contributors is much greater (few know something about the workings of OS's, but everyone knows something about something). And Linux has been around for some time now. Wikipedia was started only a few years ago and has only become widely known in the last year or so.
So the number of contributors may easily grow a tenfold (or more) in the next few years. So if you're impressed now, this is nothing. Wikipedia will take over the internet! No, seriously, one of the flaws of information on the Internet is that it is not structured. Wikipedia adds the structure that was lacking. Also, on a personal site you get personal viewpoints. Here, such pov (point of view) is less (though certainly not completely erased) by the number of contributors. I can't wait until countries like India start to get connected and contribute (at a larger scale), so the US pov's will get more opposition. We're not quite there, but still it's already huge, as you noticed. DirkvdM 09:35, 19 November 2005 (UTC)
More specifically, it's one of the most successful examples of the bazaar project development model, as first explicitly described by Eric Raymond in his essay The Cathedral and the Bazaar based on his observations of the Linux development model by Linus Torvalds. It was highly innovative as one of the first large-scale applications of the model to a non-software project. Credit also has to go to the wiki concept, which provided the technical means to make it happen, Jimbo Wales for the very substantial financial contribution he has made in hosting the project and, for some time, acting as its benevolent dictator, and also, in the beginning, Larry Sanger, whose early efforts to establish the culture of the place were a huge contribution. Beyond that, there's a cast of thousands who deserve credit. --Robert Merkel 09:54, 19 November 2005 (UTC)
And by all means, feel free to contribute to Wikipedia, check out Wikipedia:Welcome, newcomers for more info. Akamad 22:54, 19 November 2005 (UTC)
Wikipedia:Technical FAQ provides some interesting information on the mechanics of how this works, what the components are, etc. Lots and lots of open-source software. As for POV, I've been impressed by what I've seen. Contributors seem enthusiastic about learning and sharing, and are open to new information, corrections and perspectives. Yay. --Avijja 10:16, 20 November 2005 (UTC)
Have you looked at any articles about politics? Such as communism. Or, say, Cuba. Loads of revert wars there with more stress on pov-pushing than basic info. I've largely moved away from those because you just can't 'win'. This really needs t be dealt with, and I don't really know how. Having said that, any source on these subjects is likely to be biased. It's just in the nature of the subjects. Wikipedia has the potential to overcome this pov nonsense by giving, for example, first the basic facts anyone agrees on and then all pov's, so people can make up their own minds. But as long as neutral people shy away from such articles and leave them to the pitbulls that is not likely to happen. This really is a major issue on Wikipedia. Or else it should be. DirkvdM 12:40, 21 November 2005 (UTC)

[edit] Even tried multi

O all-knowing Wikipedia, to whom no HTTP error is too obscure, pray tell what be the multi in the 404 error text "Even tried multi"? Because w:Multi sure doesn't help. —Blotwell 07:42, 19 November 2005 (UTC)

Pay no attention to the Wikipedians behind the curtain. According to Google, you can search here for "even tried multi" and "HTAA_MULTI_FAILED". --Ancheta Wis 11:26, 19 November 2005 (UTC) Following my own advice, I see that the URL which generated this 404 error is "Not found - file doesn't exist or is read protected [even tried multi]".
Googling for the error text gives the source code of whatever Web server produces that message as the first hit. From there, I see that the error is produced in code that does "multiformat handling".
Looking up "HTTP multiformat handling", it seems that the idea is to allow a URL to still be valid if a file's extension changes (because the file is put up in a different format). If the server can't find the exact file you requested, it looks for another file with the same base name and a different extension. If it fails at that, then it just gives you the 404 and informs you that it "even tried multi". rspeer 19:15, 19 November 2005 (UTC)

[edit] A nuclear reaction effect

I am trying to remember the name of a phenomenon. While touring a nuclear reactor, I remember looking into one of the cooling pools and seeing the core (or rather what one can see of the core, as it is not the core itself, obviously). There was a blue light emanating from it and I asked my dad about it. My recollection of what precisely is fuzzy (hence my desire to remember the name), but it seemed that the light was a result of super-excited particles tearing out faster than the speed of light (in water) and reacting with the water, creating the eery blue light. I recall stumbling upon the name and I believe it was Something Effect (imagine that), something being the actual name. I believe it started with an M, but I'm not certain. If someone knows the name that would be of great help, then I could read about it again.

--Mogman1 08:09, 19 November 2005 (UTC)

In the words of Chairman Kaga, "if I am not mistaken", that would be Cherenkov radiation, caused by beta decay. - Nunh-huh 08:16, 19 November 2005 (UTC)
Also spelled Cerenkov radiation --Ancheta Wis 13:43, 19 November 2005 (UTC)

[edit] Static electricity question

Okay, it's getting to be the time of year for cold weather, fleece jackets and static electricity. So here's a question that's baffled me for a while.

Suppose my jacket has acquired a lot of static charge. If I am holding or wearing the jacket and I touch something metal and grounded, I get a bit of a shock. But if I take the jacket off and touch something metal and grounded through it - so here the fleece and the metal are in contact, and my finger is not between them - I get a much larger shock.

The explanation I had thought of was that the more direct contact between the fleece and the metal meant there was less resistance for the static discharge, resulting in a stronger spark, and my finger would still be next to the spark and feel it.

But here's the weird thing. Suppose I take the jacket off and put it over the back of a chair with a metal frame, without touching the frame. There's no static discharge. But if I then touch the frame through the jacket, then I get a big static shock (and the fleece becomes much less staticky). Why does that happen? Why won't it discharge until my finger is there?

--rspeer 19:04, 19 November 2005 (UTC)

You must be from the northern hemisphere. Imagine the smile on the face of a Kiwi when he reads your opening sentence. :)
Anyway, a first consideration is that when you take off the fleece jacket that will make it extra staticky (as you named it so eloquently). Other than that I can not think of an explanation. But in your last case I wonder how you would know there is no static discharge between the jacket and the chair. Do you do it in the dark to watch for sparks? DirkvdM 14:03, 20 November 2005 (UTC)

[edit] Resources vs. Reserves

what is the difference between resources and reserves

Check factors of production (the economic meaning of "resource") and reserve (second definition), if you're talking about economics. (I hope this isn't homework!) --AySz88^-^ 22:03, 19 November 2005 (UTC)

[edit] Conjugate Acid/Base pairs

Would this be a correct definition of a conjugate acid/base pair: Conjuage acid/bas pair is the acid and base that is formed from the acid after the romoval of one proton. eg H3PO4 / H2PO4 where the H3PO4 is the acid conjugate pair, and the H2PO4 is the bas conjugate pair.
Thanks for your help --144.139.163.41 23:27, 19 November 2005 (UTC)

Yes, that's correct, except it should be H2PO4−, because it's a negatively charged ion. —Keenan Pepper 02:50, 20 November 2005 (UTC)

[edit] November 20

[edit] Subatomic particles electric charge

Hi, was wondering if any body knows what actually gives a subatmoic particles (protons, quarks, etc.) their electrostatic/electrostatic charge??

Thanks,

Matt

It's an inherent property, just like mass. To quote the Electric charge article, "Electric charge is a fundamental conserved property of some subatomic particles." --Borbrav 01:32, 20 November 2005 (UTC)
In other words, they're just like that and nobody knows why. Maybe God made them that way. —Keenan Pepper 03:02, 20 November 2005 (UTC)
Charged particles attract or repel each other by the exchange of virtual photons; maybe that will give you some enlightenment. —Keenan Pepper 03:07, 20 November 2005 (UTC)
Protons get their charge from their constituent quarks, but no, as far as I knows no one knows why they have such a charge or how it arises. Incidentally, it is believed that the mass of a particle arises from interactions with hypothetical Higgs bosons; that is, without the Higgs boson particles have no inherent mass. This concept does not appear to be discussed in the Mass article, and I lack a more detailed understanding, so I cannot explain further. — Knowledge Seeker দ 03:09, 20 November 2005 (UTC)
It's discussed at Higgs boson and Higgs mechanism, although the explanation isn't complex enough to explain fully and probably too complex for most people to read well. (A great compromise.) -- SCZenz 15:49, 20 November 2005 (UTC)
For a very technical answer: in Quantum Field Theory, the conservation of charge arises from the mathematical symmetries of the Dirac equation by Noether's theorem. This method gives that fermions have a charge of ±1 in some units—for electrons/positrons, this is ±1 elementary charge. However, it is not known why the charges of quarks are exactly ±1/3 or ±2/3 of this value, a property very important to the fact that atoms are neutral. -- SCZenz 15:49, 20 November 2005 (UTC)
In Kaluza-Klein theory, both charge and mass arise as the motion of a particle in a higher-dimensional manifold. linas 23:50, 23 November 2005 (UTC)

[edit] Choked unconscious

If you are choked unconscious with your eyes open, do they remain open for the full period of your unconsciousness?

I wouldn't think so. So long as you are alive I would expect the brain's function of closing eyes when not in use to continue. However, if you were choked so near to death that significant brain damage occured, then perhaps that part of the brain would no longer work, after all. StuRat 03:47, 20 November 2005 (UTC)

[edit] LDR history

Hi all if someone knows please tell me when is LDR (light dependent resistor) is invented and by whom. No useful results on google (searched "LDR "invented by"" and "photoresistor "invented by""). Urgently needed. Thanks! --antilived T | C 08:16, 20 November 2005 (UTC)

You'd probably be better off searching for 'photodiode'. - mako 09:04, 20 November 2005 (UTC)
The first result on google have the date and person but is 'photodiode' the same thing as 'LDR'? As far as I can remember LDR allow current to past both ways. --antilived T | C 09:14, 20 November 2005 (UTC)
  • Nope, an LDR isn't the same thing as a photodiode. Try searching on "selenium cell", this was the first type of LDR and I think it was invented around the end of the 19th century. --Bob Mellish 16:35, 21 November 2005 (UTC)

[edit] swelling under both ear ,excessive growth of gland due to face seem eagly can it cure?

Dear sir, i have the problem regarding the swelling around both ear at the lateral part of the ear i meet to some doctor to reduce that swelling ,but it goes invain due to such swellin on the face face seem to very eagly,

some doctor told it is the excessive growth of the saliva gland ,i dont know what is the actual reason behind the but it is not due to the obesity,the inflamation like the growth of laterl part of chick under ear and around the ear and on the jaw ,please sugget the remady on this thanks

It would be helpful to know precisely where the swelling is. For example, swelling of the external ear, or pinna, presents a completely different problem than swelling of the parotid gland or the angles of the mandible.

Assuming your doctor is correct in that the swelling is located in the parotid gland, the problem could be any of a number of things: viral parotitis (mumps), autoimmune disease such as Sjögren's syndrome or Miculicz syndrome. An important criterion for diagnosis would include the time line of symptoms-- i.e., how suddenly the swelling appeared, and how long was its duration.

In any case, you might want to prevail on your doctor to provide more information, or to refer you to a facility or another doctor that can. Some of these conditions are not trivial, and their significance to health goes beyond simply being a cosmetic liability. --
Mark Bornfeld DDS
dentaltwins.com
Brooklyn, NY 17:02, 20 November 2005 (UTC)

I agree, consult another doctor if the first one can't help. This sounds like it could be an indication of a potentially serious condition. StuRat 07:07, 21 November 2005 (UTC)

[edit] Vacuum metal deposition

I'd like to write a Wikipedia article on VMD, but finding sources is pretty hard. Not only that but several sources say different things. One says gold will bind to fingerprints, other says it will bind to surrounding surface. One says it will release ions, other says it releases atoms. Can someone provide a definitive or at least a reliable source detailing the procedure? - Mgm|(talk) 16:30, 20 November 2005 (UTC)

I would suggest that your title is ambiguous, and this might be the reason for your difficulty. Do you mean to discuss chemical vapor deposition or sputtering methods? Both will produce thin films of high purity metal on surface, but by different mechanisms. Physchim62 (talk) 16:48, 20 November 2005 (UTC)
  • Most sources talk about evaporation. Does that cause gold and zinc particles to ionize? - Mgm|(talk) 17:28, 20 November 2005 (UTC)
    • Sounds like sputtering, which releases atoms, or possibly Au2 molecules in the case of gold. Note: to ionise a gold atom requires 890 kJ/mol, about the same energy as to cleave three carbon–carbon single bonds... Physchim62 (talk) 08:13, 21 November 2005 (UTC)

[edit] ph of solution when weak base added to weak acid

How does one calculate the pH of a solution when a weak acid is added to a weak base? How does the method differ to weak base and strong acid etc. Is it acid specific?

Such a question is off the specification for my Chemistry course, the teacher didn't know so I'm interested!

---DK

This can be a very tricky question indeed! The answer to this questions depends on how accurate you want your calculations to be. What you need to do is to essentially use a different set of equations where the assumptions for calculating pH are slightly relaxed. --HappyCamper 22:23, 20 November 2005 (UTC)
Well I have no experience in the field. The general difficulty of the course is simply a weak acid-strong base or vice versa titration. Can you give me a rough plan on how to tackle such a question? They all carry the format of a volume and concentration of weak acid with the a weak base with given concentration and volume and Ka for the weak acid.

The general solution for the case of a weak acid/weak base leads to a cubic equation for the hydrogen ion concentration, which is obviously not simple to resolve. In general, weak acid/weak base titrations are impossible to perform with a coloured indicator or a pH meter, although they are sometimes possible by conductimetry. This is probably why they are not on your course specification. Physchim62 (talk) 07:05, 22 November 2005 (UTC)

[edit] Unsuccessful diet pill

Greetings;

Does anyone know the name of an early unsuccessful pill that tries to interfere with the proton-motive force inside mitocondria?

Regards,

206.172.66.150 18:50, 20 November 2005 (UTC)

It rings of a bell, but I can't remember at the moment; what it probably does is try to make "holes" in the walls between the matrix and intermembrane space of the mitochrondria, that way, energy production from glucose is less efficient, ie. instead of 36-38 ATP per glucose molecule, it is 20+ or even less or something. Hence, you burn more food/glucose (and fat which is converted to glucose) for the same amount of activity. This is dangerous of course, because if it ends up being that it takes more energy to metabolize food than it produces, then you have an energy loss just by thinking or breathing, rather than merely slowing down energy production. I've come across the article before. This should lead someone else in the right direction. -- Natalinasmpf 21:16, 20 November 2005 (UTC)

  • Was it based on dinitrophenol (DNP)? The following web page was the top of the quick google search i did. David D. (Talk) 21:19, 20 November 2005 (UTC)
  • That sounds just about right. -- Natalinasmpf 21:37, 20 November 2005 (UTC)
  • make "holes" in the walls between the matrix and intermembrane space of the mitochrondria -- Yep!!!!!!!!!!!! that sounds exactly like the material I should be addressing on my "Oxford Tutorial", in fact, the first part of that presentation talks about how the proton-motive force was setup in the first place. And I know that it's the inner mitochondrial membrane that prevents the protons from diffusing back into mitochondria, instead they have to go through specialized proteins embedded into the mitochondrial membranes called "ATP synthases" that makes ATP from the energy gained from protons going back to mitochondria. So if DNP makes "holes" in the walls of mitochondria membrane than it allows protons to diffuse back into the mitochondria, defeating the purpose of the original membrane scheme. (I'm the original question asker, I came back to school so my IP is different). Thanks a loooooooooooooooooooooooooooot 129.97.252.63 18:46, 21 November 2005 (UTC)
  • To feel comforted about your success, does this project documenting the process of phosphorylation discuss and how it was set up deal with endosymbiotic theory and how the eukaryote evolved, or are you dealing with something else? -- Natalinasmpf 23:16, 21 November 2005 (UTC)
  • Dear Natalinasmpf: actually the topic is really simple -- "Describe how the proton-motive force is set up and how interfering with the proton-motive force was the focus of an early unsuccessful diet pill.", and we're required to do a short presentation on it. No fancy topics like the endosymbiotic theory or how eukaryotes evolved -- too much for a 5-minute presentation! ;-) 129.97.252.63 05:52, 22 November 2005 (UTC)
  • You may want to rephrase that question, I'm not quite sure how you are trying to connect endosymbiosis to the original question? More relevant would be to consider the function of the mitochondria in brown fat with regard to babies and thermoregulation. Or to consider how plants generate heat to give off volatile chemicals, such as the arum species (the ones that smell like rotten meat), to attract flies. David D. (Talk) 23:30, 21 November 2005 (UTC)

Dinitrophenol is an "uncoupler". It dates back to the 1960s as a tool for investigating mitochondrial electron transfer in vitro and in cell cultures, but it was never marketed or even entered in clinical trials as a diet pill because of obvious toxicity potential. alteripse 21:46, 20 November 2005 (UTC) I stand corrected. References are always better than top o' the head. Thanks for the additional info. alteripse 22:19, 20 November 2005 (UTC)

  • DNP was definitely used as a diet pill. I was just not sure if it was still on the market. Some more research shows that it was banned by the FDA in 1938. Quotes from the following paper Obesity Part 2:Pharmacotherapy by David E Oeser, Pharm.D. are as follows:
"Dinitrophenol (2,4-DNP) was introduced in 1933 for the treatment of obesity and soon found its way into numerous “anti-fat” patent medicines (Tainter et al. 1933). Dintrophenols induce weight loss by uncoupling oxidative phosphorylation, thereby markedly increasing the metabolic rate and body temperature. However, the use of these compounds was abandoned in 1937 because of reports of severe intoxications and deaths. Dinitrophenol is used currently as a wood preservative and insecticide. Tainter ML, Stockton AB, Cutting WC. Use of dinitrophenol in obesity and related conditions JAMA 1933;101:1472-5. "
However, despite the known dangers, it appears the drug is still available. Two health pages caught my attention that said that "It is currently being marketed and used by body builders, and is also advertised and marketed on the Internet. The extent of DNP use is unknown at this time." [47] [48] David D. (Talk) 22:17, 20 November 2005 (UTC)
Went to a body building forum and sure enough they are taking DNP [49]. Could body builders become extinct in the near future? David D. (Talk) 23:27, 20 November 2005 (UTC)


Thank everyone sooooooooooooooooooooooooooooooooooooo much for all these helpful hints! Now I can finish this little "Oxford Presentation" that I'm going to give tomorrow. 129.97.252.63 18:46, 21 November 2005 (UTC)

We need a page on dinitrophenol. alteripse 12:20, 22 November 2005 (UTC)

[edit] Synthesis of melanin

Can you help with the equation for the synthesis of melanin?


Substrate enzyme product

              tyrosinase

See our article melanin. I put the reactions there. alteripse 22:16, 20 November 2005 (UTC)

[edit] Subject: DVD programming -- scene selection menus, etc.

Does anybody have any good references for the "computational model" underlying entertainment DVDs? There's quite a bit of variation in the way the scene selection and other menus work, and in the kind of effects that can accompany the special features. It seems that each DVD's menu tree must, in effect, be written in some kind of programmng language, but obviously one that is ultimately represented in some nicely device-independent form, since the DVD's can not only be played on general-purpose computers (both PC's and Macs) but also of course on dedicated, single-purpose DVD players. I'm curious to know what the specification of that "programming language" is, and what features it supports. (And it's the low-level, on-disk form I'm curious about, not any higher-level representation that a particular piece of DVD authoring software might present.) Steve Summit (talk) 19:52, 20 November 2005 (UTC)

I'm not sure on the specifics, but this page looks promising if you want the nitty gritty. All to do with virtual machines and bytecode. Tzarius 23:08, 20 November 2005 (UTC)
Hey, that looks like the stuff! Their full doc kit is payware, and the crippled excerpts on the site are so badly written that I'm not too inclined to pay for their "e-book" if it's more of the same, but the site gives good background, and suggests lots of terms to use for more-targeted searches. Thanks! Steve Summit (talk) 22:26, 21 November 2005 (UTC)

[edit] November 21

[edit] Arbiter (electronics)

Could a few people with experience in electronics and physics verify the factual accuracy of arbiter (electronics). There has already been some discussion on the talk page and this article will be part of an RfC I will start tomorrow. —R. Koot 01:10, 21 November 2005 (UTC)

[edit] E. coli size

Would someone tell me the size of an average E. coli bacterium, length and width. Thanks. -- Миборовский U|T|C|E 03:39, 21 November 2005 (UTC)

I'm not so sure, but apparently one of the weighed 665 femtograms... --HappyCamper 04:14, 21 November 2005 (UTC)
"straight rods from 0.5-1 to 1.5 micrometer in diameter and from 2 to 6 nanometer in length, depending on the growth phase and environment." [50]
Rozen and Lenski (2000; Am.Nat. 155:24-35) reported two strains, one was 1.251 ± 0.051 x 10-15 L, the other was 0.700 ± 0.008 x 10-15 L
Thanks. -- Миборовский U|T|C|E 00:24, 22 November 2005 (UTC)

[edit] GARBAGE

What happens to garbage when it is thrown down the chute?

It is simply passed through a process where the total entropy of the garbage is increased :-) --HappyCamper 04:12, 21 November 2005 (UTC)
Depending on which chute you throw it down, it either ends up in the laundry or in a dumpster and eventually on to a landfill. Dismas|(talk) 05:20, 21 November 2005 (UTC)
Some buildings also have a chute which leads to an incinerator. Those are usually marked, as not everything should be incinerated, such as a mercury thermometer. StuRat 07:00, 21 November 2005 (UTC)
Is the speed of the garbage regulated at it goes down the shoot, or is it allowed to go as fast as it can? I imagine you could get some fast moving garbage in a high-rise building.--Commander Keane 10:14, 21 November 2005 (UTC)
Like a cat falling off a building, it should stabilise at a certain speed due to air resistance. But in a chute the air has less freedom to escape to the sides, so presure will build up beneath the garbage. How much depends on the size of the bag and whether it is in a bag in the first place. I suppose there will be rules concerning this (especially the bag bit, which will likely make a big difference due to floppyness). DirkvdM 12:53, 21 November 2005 (UTC)
That's the terminal velocity. Garbage is typically light enough, and garbage bins are constructed of such thick material, that the garbage won't destroy even an empty bin. However, if someone dropped a series of canon balls or bowling balls down the chute, they would make an awful noise and seriously dent an empty bin, at the very least. Rubber flaps spaced down the chute could slow the rate of descent, but would also get covered with rotting food, and stink up the chute quite a bit, unless some automated cleaning system was also installed in the chute. StuRat 19:18, 21 November 2005 (UTC)
Jump down one and see. :) I actually saw that in a film once, and they landed in the basement on a pile of garbage, which broke their fall, so make sure it hasn't just been collected. :) Once you've done this, could you tell me the results, because these chutes don't exist in the Netherlands, so I can't try it myself. DirkvdM 12:53, 21 November 2005 (UTC)

[edit] Calculus Problem Error

I've been helping a student with his calculus, but can't seem to locate the error here. Maybe you guys can help ?

- A piece of heavy stock paper is cut into a circle with a 4 inch radius. The paper is cut from one edge to the center and shaped into a cone-shaped holder. What is the max. volume of the resulting cone ?

V = piR^2H/3 \;

Drawing the cross section of half the cone, we get:

+
|\
|.\
|..\
|...\
|....\
|.....\
|......\4
|.......\
|........\
|H........\
|..........\
|...........\
+------------+
      R


Using the Pythagorean Theorem, we get:

H^2 + R^2 = 4^2 \;

Or:

H^2 + R^2 = 16 \;

Or:

R^2 = 16 - H^2 \;

Or:

R = \sqrt{16 - H^2} \;

We can now plug this into the volume formula:

V = piR^2H/3 \;

To get:

V = pi[\sqrt{16 - H^2}]^2H/3 \;

Or:

V = pi(16 - H^2)H/3 \;

Or:

V = (16piH - H^3)/3 \;

Or:

V = 16piH/3 - H^3/3 \;

The solution is to set the first derivative equal to zero, using the power rule:

V' = 16pi/3 - H^2 = 0 \;

So:

16pi/3 = H^2 \;

Or:

\sqrt{16pi/3} = H \;

But this gives us a cone height of 4.09, which is larger than the circle radius of 4.00 we had to start with. What went wrong ? StuRat 05:24, 21 November 2005 (UTC)

The error appears to be at the following step:
V = \frac{\pi \left ( 16-h^2 \right ) h}{3}
You forgot to distribute the π. The next step should be:
V = \frac{16 \pi h - \pi h^3}{3}
V = - \frac{\pi h^3}{3} + \frac{16 \pi h}{3}
V' = - \pi h^2 + \frac{16 \pi}{3}
0 = - \pi h^2 + \frac{16 \pi}{3}
\pi h^2 = \frac{16 \pi}{3}
h^2 = \frac {16}{3}
Taking the positive root only:
h = \sqrt {\frac{16}{3}} = \frac{4 \sqrt{3}}{3} \approx 2.309... which is less than the paper circle's radius of 4.
Hope that helps! (and hope that's right!) — Knowledge Seeker দ 06:30, 21 November 2005 (UTC)
Yep, that's it, just a basic math error. Thanks ! StuRat 06:28, 21 November 2005 (UTC)

[edit] Can hypothermia/frostbite cause a person too enter a comotose state?

I'm writing a story in which a young boy in an attempt too escape a dangerous situation starts his snow mobile and drives away wearing only regular street clothes (Jeans, t shirt, hoodie). After roughly an hour of driving away completely without direction, the boy turns and only too have the machine break down on him. After over an hour of walking in the tempratures (5 - 20 below) he passes out and is later recovered and brough too a hospital. What I'm asking ultimately is if these circumstances could cause a person too enter a comotose state or unconcious state?

Thank you for your help. Fullmetal66.230.81.77 06:17, 21 November 2005 (UTC)

Severe hypothermia will cause unconciousness, but once normal body temp is restored the person is usually either awake or dead. It might be possible, in a few cases, for them to suffer oxygen depletion to the brain and some subsequent brain damage as a result which causes a coma. However, as the oxygen needs of a body in the low metabolic state of hypothermia are so low, it would take much longer than usual for this brain damage to occur. A person who has "drowned" in cold water might manage to suffer enough oxygen deprivation to end up in a coma, for example.
Frostbite doesn't figure into any of this as that affects the extremities, ears, and face, not the brain. A person would be long dead before frostbite affected the brain.
BTW, "unconciousness" isn't really the right term for the state of a person in severe hypothermia. While they are not concious, they also have a greatly reduced pulse rate, suppressed breathing, and much lower metabolic rate than is normally associated with unconciousness. This state most closely resembles the hibernation stage of other animals.
Also, I think at those temps, for 2 hours, in those clothes, a young boy would be dead, not in hypothermia. You might want to make it a bit warmer than that. StuRat 06:39, 21 November 2005 (UTC)
Whoever said which temperature scale it was? AFAIK 5 to 20 below in your silly "Fahrenheit" thingy is colder than 5 to 20 below in Celsius which everyone else uses. — JIP | Talk 08:42, 21 November 2005 (UTC)
20 below is still plenty cold in Celsius. As far as the metric system, temps seem to be the least valuable thing to change to metric, since they don't suffer from the division into groups of 3, 128, 5280, etc., like other types of measurement do under the US system. Neither system works as well in formulae as the absolute scale systems of Rankin/Kelvin. The most valuable thing to change over to metric would be time, with it's weird divisions of 60, 24, 7, 28-31, and 365.25, which make all time math a real pain. The only division we are really stuck with is the number of days in year, but the rest we could fix in a milliday. While we're at it, let's all go to UTC time and drop these silly time zones and daylight savings time, which are no longer appropriate with the Internet and other worldwide communications systems. It really is the same time everywhere, measured from the Big Bang (or Creation from your favorite diety), we just pretend the time is different in different places. StuRat 17:50, 21 November 2005 (UTC)
True, Kelvin makes more sense, but it's based on Celsius, so at least substraction and addition work the same for the two (not multiplication and divison) and that's what's most useful in everyday life. Kelvin has the advantage of an absolute point zero, but the disadvantage of working in the hundreds for everyday temperatures, where variations are in the tens or single digits. So Celsius has the best of both worlds - it's a more 'human' scale and compares more easily with Kelvin.
Time measurement is a real bitch though. We need both the day and the year, but 1 year = 365,24 days is a bloody nuisance. Also, again, in human terms, the second is a convenient measurement, just like the metre is something you can measure with your hands and a kg is a weight you can comfortably lift. But if you use the day as a basis then you'd get something like the milliday, which is way too long, and the microday, which is way too short. A second is about 1/85000 seconds long. So we could change it to something like 1/100000 day, but that would be too complicated to express in the standard notation. Is there a 1/100000 prefix? And anyway, why do these prefixes work in multiples of 103? Why not 104 or 1010. Well, ok, power 10 would be way too big, but 4 is a more round number. Then again, we've gotten lucky in this binary age, considering that 210 = 103. So I suppose the millis, micros and kilos are here to stay. If only we could get people (and hard disk producers) to specify more clearly which kilo they mean - binary or decimal. Funny, by the way, that the most used unit in computers is the byte, which is 23. There's that power 3 again. What gives? DirkvdM 12:36, 22 November 2005 (UTC)
Yea, that almost caused a major problem at work. They had used almost a "terabyte" of disk space and thought that meant their "terabyte" of storage capacity was almost used up and they were about to take drastic actions (start deleting things at random). I pointed out that the disk usage was a decimal terabyte and their storage capacity was a binary "terabyte", which is about 10% bigger. This meant they had enough extra space to order and install new disks, well within the rate of growth of data on the system. StuRat 19:05, 22 November 2005 (UTC)
Looks like it's the number 365,24 that we're stuck with, as we bloody well can't change the rotation or orbit times of the Earth. But what we can change is everything else. Why not switch to a 19-based numbering system? Then the number written as "100" would mean 361, which is 98,84% of the number of days in a year. Thus a day would be a centiyear. A milliday (or ten microyears) would be about 12,60 of our current seconds. — JIP | Talk 13:54, 22 November 2005 (UTC)
I take it that's meant as a joke ? At least I sure hope so ! StuRat 18:57, 22 November 2005 (UTC)
I wouldn't dismiss that idea too fast (a 'joke' can easily lead to a great insight). Though ultimately I do. Changing everything else for the sake of time measurement is a bit of a stretch, but not too unreasonable if the advantages are big enough. Which they aren't. The year is still not exactly '100' days. And its not a kiloyear (although the reasons for sticking to the power three prefixes won't make sense anymore). And the millisecond is too long. And base 19 seems to cumbersome, mostly because it's a prime number. It would make more sense to shorten the second a bit to have 100 000 seconds in a day. Although that also has the problem of not being a multiple of 103. And it doesn't solve the 'days per year' thing. DirkvdM 11:09, 23 November 2005 (UTC)
As I said, the only thing we're stuck with is 365,24 which is the number of days in a year. Days and years are the only time measurements that are based on natural occurrences and whose length thus can't be changed. This means we can't change their relationship either. This is a shame, because 365 (let alone 365,24) is a "rough" number with few divisors and, most importantly, very few (if not none) integer-based roots that are integers or even close to integers. Everything else we can change. Hours, minutes and seconds are completely artificial and can be redesigned at will. A million seconds per day would be good for calculations but then a single second would be too short to be of practical use. But if we change to a 20-based system (which has more divisors than a 10-based system), then we could have a day be "10000" seconds, where one second would be 0,54 of our current seconds. — JIP | Talk 11:54, 23 November 2005 (UTC)
  • Sounds interesting, please let me know where I can read the story once you finish it. - 131.211.210.16 08:28, 21 November 2005 (UTC)
  • Returning to the original question, I don't think it would be possible for anyone to drive a snowmobile for "roughly an hour" in street clothes at a temperature of -5 C, certainly not at -5 F (and people who say "below" usually mean F). The person would be disabled by hypothermia long before that. Note that wind chill has to be taken into account since the machine is moving.
Very young children can survive hypothermic experiences that would kill an older person -- see this news story, for example. But from what I've read, this wouldn't happen to someone old enough to drive a snowmobile.
--Anonymous, 00:05 UTC, November 22, 2005

[edit] Gravity

What would happen if there was a place in the world where gravity was heavier, or lighter, than everywhere else? What would that place look like? If it was on sea, would the water level be different? — JIP | Talk 08:41, 21 November 2005 (UTC)

There is. All over the world local gravity varies slightly due to differences in the composition of the earth (types of rocks, densities & masses, etc). It's not really noticable though without specialist equipment. AllanHainey 10:13, 21 November 2005 (UTC)
However, if the gravity varied in a noticeable way, what would it cause? Would a large enough variation in gravity cause the sea level to be non-even? — JIP | Talk 10:21, 21 November 2005 (UTC)
Most probably yes. Changes in gravitational fields already cause significant changes in sea levels – see tide. –Mysid 12:43, 21 November 2005 (UTC)
Most certainly, I'd say. You'd get that if the centre of gravity of the planet weren't at the geometric centre. Maybe because a collision with another planet during the solidification stage knocked off some bits or added the metal core of the other planet to the side. That would attract the water on the surface to that side. The rock would want to go there too, but, being solid, it can't. The instability this causes would, however, probably also cause tidal friction in the rock, causing it to liquifiy, and over time (millions of years?) the heavy elements (metals and such) would move to the geometric core and things would be back to normal. DirkvdM 13:10, 21 November 2005 (UTC)
Does this mean that, if by some hypothetical strange accident, there were a place in the sea (say, a few square kilometres in area) that constantly had significantly different gravity than the surrounding areas, the water level would actually be locally uneven? If the gravity in that area was heavier, there would be a mound of water standing out from the sea, and if the gravity was lighter, there would be a hole in the water? — JIP | Talk 13:21, 21 November 2005 (UTC)
I think you have it backwards, a stronger force of gravity would cause the water level to be lower in that area. Since gravity acts over a wide area, the region would be many miles across, however. StuRat 17:21, 21 November 2005 (UTC)
I was intuitively thinking that water tends to flow from areas of lighter gravity to areas of higher gravity, so more water would stack up at the point of higher gravity, because water takes up space and can't move through itself. Likewise, areas of lighter gravity would tend to empty of water. But I suppose my intuition was wrong - and the concept of water flowing upwards instead of downwards seemed pretty strange anyway. — JIP | Talk 18:15, 21 November 2005 (UTC)
You might be interested in the concept of mascons, mass concentrations which are found in the moon, and are significant enough to cause low lunar orbits to be significantly unstable. They remain there, despite tidal effects; this is probably due to the lack of active geology, IIRC. Shimgray | talk | 16:50, 21 November 2005 (UTC)
Not to ignore other comments here, but consider this - an easy way to get more gravity in one place is to have the dense center of the Earth off-center (as mentioned). Then, the Earth would wobble, not spin. It spins on the center of mass, not the geometric center. But, there's one more issue - the sun. The center of the Earth is attracted to the sun - but if the center was off-center, there would be a strong pull of one side of the Earth toward the sun. Eventually, that side would always face the sun. Perhaps the spin would change so that the planet would roll around in orbit with the north pole pointing right at the Sun (I think Uranus does that). It could also slow down so it makes one rotation each orbit around the sun (keeping the same side facing the sun) just like the Moon does around Earth. --Kainaw (talk) 21:37, 21 November 2005 (UTC)
Ah, that's an interresting observation. The rotation of the Earth causes a centrifuge-effect and everything to want to fly out into space. But gravitational force is stronger. However, when there's that wobble, that would 'fling' the water to the far end. But the 'off-centre gravity centre' will also pull at it. Which one wins here? Or do they both win, giving the same effect as we normally have with tides - a bulge at both sides that causes two tides per day.
StuRat, you disappoint me. Imagine your hole in the ocean. Then imagine the water at the edge of it. Where does that go? Fill up the hole, of course. Until it forms a sphere around that incredible mass. But this would have to be a really incredible mass to have any effect that significantly 'overrides' the gravitational pull of the Earth. In other words, the centre of gravity would shift, just as in the original question. And the effect would be global. And the 'bulge' would be just as (in)visible as the bulge created by the curvature of the Earth. In the gallbladder thread above you pointed out my stupidity. Now we're even. And of course I expect you to now start kicking yourself. :) DirkvdM 15:24, 22 November 2005 (UTC)
I will do no such thing. A depression in the water can be supported by a variable gravity field, as occurs now in locations of low tide. However, as I pointed out previously, the scale of gravity requires that any such depression be miles across, not localized. As for centrifugal or centripetal forces, that is a measureable effect, but is less than 1/1000 the strength of gravity, on Earth. Any significant off-center mass on a body the size of the Earth will quickly even out, but not so on small asteroids and moons, which have a small enough gravity field to permit uneven distributions of mass. The most uneven distribution of mass on Earth which can be supported is the difference between the lighter continental plates and heavier oceanic plates. StuRat 17:14, 22 November 2005 (UTC)
Understanding why water doesn't rush in from the sides during low tide is a difficult concept, and involves the modern theory of curved space. Much as planets in orbit appear to be constantly changing direction under normal space theory, but are going straight under curved space theory, the bulge or depression observed in oceans during high and low tides can be thought of as flat in curved space. StuRat 17:33, 22 November 2005 (UTC)
I don't quite follow your reasoning. I get the feeling we're talking about different things. For clarity, I do understand that curved space theory would make certain calculations simpler because the lines are straight - which would make that viewpoint more 'true' in a philosophical sense, but would not invalidate the more traditional view. If it has to do with Einsteinian relativity I would probably have to throw in the towel. But the Earth's gravitational acceleration is way too small for that to be noticeable, so it's basically down to Newtonian physics. And then any gravitational attractor will cause a fluid to form a sphere around it. So an extra attractor would cause a bulge. And I'm not talking about miles but on a scale of Earth's circumference because what really happens is that the the gravitational centre is put geometrically off-centre. Even if you regard it as two separate attractors (the Earth's centre and the local attractor), the water won't care. It will just react to the sum of the two forces, creating a virtual attractor somewhere in between them. DirkvdM 11:36, 23 November 2005 (UTC)

[edit] Solar power for the USA

Hi. I read a while ago that an array of photovoltaic solar panels 100 miles square in the Nevada desert or Arizona would generate enough electricity to meet all USA power needs. My question is how much would this cost (& how does this compare to the total cost of a nuclear power plant - including decomissioning cost & storage of radioactive material, etc). I'd assume that the solar array would need to be raised off the ground (say enough to allow a car to drive under it) for maintenance & that the solar panels should tilt (both to catch the sun better & to knock off any dust/sand that blew onto them) so some engineering cost would be needed as well as the costs of the panels. Anyone have any ideas? AllanHainey 10:13, 21 November 2005 (UTC)

Don't forget the energy cost. Manufacturing anything consumes energy, so this has to be subtracted from the energy benefits over the lifetime of the item. It used to be said that manufacturing a solar panel consumed more energy that the panel could ever generate. I read that recent innovations have improved this. But still, we still might not have enough energy and other raw materials to manufacture 10000 square miles of solar panel. Also, transporting energy has significant losses. Could electricity be delivered from Arizona to New York without losing most of it? Did the original calculation just add up the electricity generated (locally) and ignore increased distribution costs? Just some things to factor in. Notinasnaid 12:13, 21 November 2005 (UTC)
The nice thing about buying things on the open market is that the cost of the energy used in construction is already taken care of. As to transmission, High voltage direct current can send power an amazingly long way efficiently; the longest is the Inga Shaba line in Zaire at about 1700 kilometres (roughly 1060 miles), and there was one proposed from Brisbane to Darwin in Australia, a distance of about 3000 kilometres (over 1800 miles), which was technically feasible but the economics of the proposal were not (Darwin is far too small an electricity market to make the project viable).
That said, solar panels are incredibly expensive. They cost about 4-5 USD per watt peak power [51]. That's $4000 per kilowatt. But we'll be generous and say you might get them for 3 USD per watt if you bought them in bulk, giving a 3000 USD per kilowatt cost. Nuclear power costs, very conservatively, $2000 per kilowatt construction (and nuclear is far more expensive to build than coal or gas), and can be used all day, every day (well, not quite but I think the typical utilization is about 80%), instead of maybe the equivalent of 6 hours per day of peak production. Even once you take operating costs into account, nuclear still comes out much, much cheaper than solar. The economics of wind power are still not great, but they're nowhere near as bad as solar. That's why wind power is the most popular form of renewable energy to build at the moment. --Robert Merkel 12:03, 24 November 2005 (UTC)
I'm pretty sure it will have been meant in a for-the-sake-of-argument kind of way. It would be stupid to focus totally on one energy source (or one source of anything for that matter). Just as it was stupid to totally focus on first coal and then (now) on oil. How constant is the sunshine in Arizona? Probably very constant now, which will be the reason to put the panels there. But climatic change will be global warming globally, but locally anything can happen. What if Arizona becomes occasionally cloudy in 50 years? You'd need another energy source to compensate for that. To add to Notinasnaid's observations, how would you run a car in Vermont on solar power generated in Arizona? Either the power would have to be put into some fluid fuel the car can drive on or the car engine would have to be replaced. And that sort of thing takes time. Vermont had better find its own energy source. By the way, about the distribution cost, I mentioned in another thread that the investments in the infrastructure for the distribution of oil-products have already been made. For other energy sources we have to start anew, which is one cause for the delay in changes. DirkvdM 14:05, 21 November 2005 (UTC)
There is one other huge problem with how constant the sunshine is in Arizona...it tends to stop completely every night. Unless we want the power supply to stop at sunset, some method would be needed to replace the missing electricity, such as another power source that could be fired up each night or some massive battery storage system, which would have losses of it's own, and require a great deal of energy to create, and potentially might contain many toxic materials. Also note that this huge array of solar panels would be roughly equivalent to paving all that land as far as environmental damage. No plants could grow, due to the lack of sunlight, and no animals could eat the plants, and no animals could eat those animals, etc. This would potentially wipe out many species, such as the saguaro cactus.
There is one source of energy which we could rely on exclusively: nuclear fission. Unless the laws of physics change, that should continue to work until all radioactive material on the planet has been used up. As this is many million years from now, nuclear fusion, which doesn't require radioactive materials, should be perfected by then. The current foolish placement of nuclear reactors on the surface near populated areas would need to be changed, however. A sensible place for them would be in an old mine, on stable ground, in remote areas, with cooling towers and a military base on the surface above them. The cooling towers don't contain any highly radioactive material, so are safe, if attacked, although their destruction could take the plant offline. Hence the need for the military base with anti-aircraft missiles and anti-missile missiles, as well as concrete barriers to prevent truck bombs from reaching the towers. Radioactive waste could be stored permanently within the mine, not foolishly shipped around the country in search of a permanent home, as is done now. A breeder reactor and facility for refining the fissable material could also be located in the mine, so only slightly radioactive material needs to be shipped in, under heavy guard, from where it is mined. An underground electrical distribution system would also be needed, as high tension power lines are another natural target for terrorists. Reliance on nuclear power and electric/hydrogen fuel cell cars would significantly reduce carbon emissions and hence global warming, and would also end the dependence on foreign oil which leaves the world vulnerable to the actions of unstable governments. StuRat 17:06, 21 November 2005 (UTC)
I had meant that it would provide all the electricity currently used, not power things like cars. I'd assumed that a large bank of batteries or electricity storage sub-stations(not necessarily located there but around the national grid - think there already are a large number of these) would be needed, I should have specified this. Assuming that someone decided to do this instead of nuclear power, hydrogen fuel cells, other or localised forms of renewable energy (which all have valid arguments for them) then how much would it cost? Does anyone have any ideas of figures? Thanks. AllanHainey 09:31, 22 November 2005 (UTC)
As far as I know, there is very little capacity for storing electricity, and very few practical methods for doing it. That's why power stations run day and night, have to be extremely predictive/responsive to changes in use. and a very significant problem with the universal use of solar power. I have visited one storage system: there is a large reservoir, used to "store electricity" by pumping millions of gallons from a natural loch (lake) below. This is done during the night when there is a surplus of nuclear electricity. This is used in times of peak demand; as I understand it the whole reservoir can be drained in a few minutes. A "bank of batteries" just wouldn't cut it. So this is a technological stopper for the whole program, as I see it. Also you didn't really deal with the question: can we actually transmit power from sunny places thousands of miles to places that aren't? Again a huge technological obstacle. These aren't questions of cost. Notinasnaid 16:24, 22 November 2005 (UTC)
I agree. Storing that amount of energy is a huge problem. It's distribution could be solved, however, by "stepping up" the power to a level where losses are minimal, or even using superconductors, which would eliminate losses altogether. I also believe that solar power costs more than most alternatives, under current technology. StuRat 16:39, 22 November 2005 (UTC)
The water reservoir thing has also been thought of with an as yet unused dammed in area in the IJsselmeer in combination with wind energy.
What is the efficiency of modern flywheels? I've heard of the idea of small light-weight flywheels with extreme rotational speeds to store the braking power of a car. This could be used to locally store the energy. But it might also be used fo renergy transportation. What would happen if you attachhed a propellor to a flywheel? Would it take off like a helicopter? :) Ok, that doens't sound too practical. But what about a pipeline then? Put in a spinning flywheel that fits in snugly, use self-lubricating material and maybe give the pipe a spiralling groove in stead of using a propellor (where would the air go otherwise?). At the receiving end you could bend the pipe upwards to stop the flywheel, to regain the kinetic energy of the wheel's speed (maybe also to send it back). And then directly drive a machine with the wheel. Lots of energy transformation, so not too efficient, but nbeither are power lines. How would they compare? And we are talking about something that only costs much to build but after that has a cost-free energy source. Apart from the ecological costs like the ones you mentioned, but that's nothing compared to the ecological cost of continuing to use fossil fuels. DirkvdM 12:05, 23 November 2005 (UTC)
There's also the change in albedo to consider. A giant black square would likely have some unique effects on the climate. ‣ᓛᖁ♀ᑐ 20:34, 25 November 2005 (UTC)
100 mi² is a bit over 200 km². The Earth's surface is just over 500 million km². So it would cover about 0,0000025% of the Earth's surface. Which is peanuts. And anyway, the present surface will also absorb some sunlight, which makes the change even smaller. There will certainly be local effects, as StuRat pointed out, but globally it's nothing. The concentration of Carbon dioxide in the atmosphere, however, has increased by 40% (Carbon_dioxide#Atmosphere). Now that makes a difference. Yesterday I stated in the Science#Math_in_your_head thread that pupils should also learn how to make reasonable estimates, not just exact calculations. Thank you for proving my point. :) DirkvdM 10:40, 26 November 2005 (UTC)

[edit] Mathematical shape

Is there any special name for the shape generated by \{ x \in R^2 | |x| < 1 \and |x| \notin Q \}, which I think has non-zero area but no interior points? — JIP | Talk 11:39, 21 November 2005 (UTC)

Not sure, but this immediately made me think of z-transforms and certain implementable poles and zeroes... --HappyCamper 11:47, 21 November 2005 (UTC)

You might want to include a pic or link to the pic. StuRat 16:38, 21 November 2005 (UTC)

Any picture would only be a crude approximation, as this is all about infinite numbers. To be specific, it's an infinite series of concentric rings, all of which have radii less than 1. None of the rings touch or intersect each other, but no matter how closely you look at it, the gaps between them won't increase, as between any two rings there's another ring. — JIP | Talk 18:12, 21 November 2005 (UTC)

I don't think it has a specific name, as a shape, but the set might be named after whichever mathematician first thought it interesting enough to publish on. I'm also not an expert on such things, but it sounds distinctly fractal-ish. It also reminded me a little of the Cantor set, which is similarly impossible to properly represent with a picture (or even really visualize, for that matter). --PeruvianLlama(spit) 22:34, 21 November 2005 (UTC)

Don't think theres any special name. Removing the rationals from the real number line turns it into a "fat" cantor set. (the "fat" mapping is accomplished via the Minkowski question mark which maps rationals to dyadics; the construction of the cantor set is via dyadics (i.e. middle-third removal)). linas 00:08, 24 November 2005 (UTC)

[edit] Solution (in chemistry)

Can the elements in a solution be seperated back out into their original form? Does a solution act as a mixture or as a compound, or can a solution act as both depending on the elements in solution?

  • Yes, as long as those elements didn't react with each other (or the water) it should be possible to separate them again. How easy it is to do depends on what elements you are talking about. - Mgm|(talk) 14:15, 21 November 2005 (UTC)

One thing one should realise, that yes, you can separate solutions' components if they did not react, but every time you mix them, you increase the total entropy in the system. -- Natalinasmpf 23:06, 21 November 2005 (UTC)

  • This is an experiment you can do at home kids! Dissolve a couple of teaspoons of salt in a glass of water. Pour the water into a shallow dish and leave in a warm place for a couple of days. You retrieve the salt unchanged. We do it in 8th Grade in France (and sometimes in 4th Grade as well, depending on the school). Physchim62 (talk) 07:16, 22 November 2005 (UTC)
    • But you won't get nice, big, pourable salt grains, of course. You just get a dish with a salty crust covering it. :) Not really it's "original form", per se, but still salt, I suppose, and it's still a good experiment. In fact, I think some of the dishes in my sink might be performing it right now, unfortunately... —HorsePunchKid→龜 2005-10-22 07:20:33Z
  • I also remember some nice experiment that involved separation of salt and pepper. Can't remember what the method used was, though. - 131.211.210.16 09:28, 22 November 2005 (UTC)
  • Since salt is water-soluble and pepper is not, I would suggest slowly adding water to the salt-pepper mixture, skimming off the pepper from the top, then heating the remaining salt-water to evaporate the water and leave the salt. I imagine a centrfuge could also be used to separate the dry salt and pepper, but most of us don't have those in our kitchens, except maybe in a juicer. StuRat 18:48, 22 November 2005 (UTC)

[edit] fiber optics

How data is trasnfarred through fiber optics?

After edit conflict:

Ehm... optically. In other words, it's light that is sent through the fibres, which remains confined to the fibre because it bounces off the walls. That's what I know from the top of my head. For more see fibre optics. DirkvdM 14:16, 21 November 2005 (UTC)

[edit] mathematics

how e=mc2

  • Please read the instructions at the top of the page:
Be specific - explain your question in detail if necessary, addressing exactly what you'd like answered.

This means that you should ask your question using a full sentence, preferably more. - Mgm|(talk) 14:18, 21 November 2005 (UTC)

Oh come on, I think How E=mc²? is a perfectly good sentence. =P Well, maybe it should be How does E=mc²?. Anyway, we have an article on E=mc². —Keenan Pepper 15:07, 21 November 2005 (UTC)
What about "What the fE=mc²?"? DirkvdM 15:48, 22 November 2005 (UTC)
Because energy has mass. Everything exhibit both wavelike and particulate properties, therefore E=mc². One cool implication of this is that when absolute zero is reached, nothing exists. -- Миборовский U|T|C|E 00:28, 22 November 2005 (UTC)
You haven't read our article on zero point energy, obviously! Physchim62 (talk) 07:18, 22 November 2005 (UTC)
Neither have I. But what about this one then... Einstein showed that Newton's laws of motion aren't valid where there is motion. Which sucks. For Newton, that is. But still we use them everyday. So do we suck too? DirkvdM 15:48, 22 November 2005 (UTC)
But it is only when that motion becomes a significant fraction of the speed of light, that the deviations from Newton's results become noticeable. In "the real world" (excluding particle physics) nothing moves that fast, even a Ferrari. StuRat 17:08, 22 November 2005 (UTC)
True, but we should also mention that relativistic effects do affect everyday life. Have you ever wondered why gold looks the way it does? Or why mercury is a liquid at room temperature? All due to relativistic effects! --HappyCamper 01:44, 23 November 2005 (UTC)
You say 'noticeable'. But in theory it has an effect at any speed. Notice the header is 'mathematics' and mathematicians, unlike physicists, do take minute deviations like this serious. DirkvdM 11:50, 23 November 2005 (UTC)

[edit] Internet telephony

How will a Internet telephone be? Is Vonage a Internet telephone? What is the minimum speed/bandwidth that a Internet telephone need? Should I have a Internet connection in my area to have a vonage phone? What is the quality of calls made in a Internet phone? Is it similar & continuous like any other ordinary phone? Will I get a Internet conection with vonage or is it seperate?

See Internet telephony. --David Iberri (talk) 22:33, 21 November 2005 (UTC)

[edit] stomiatoid fish

i need to know what a stomiatoid fish is, what it eats, the climate in which it lives, etc. thank you 68.38.82.246 15:03, 21 November 2005 (UTC)

Take a look at Stomioides nicholsi. --JWSchmidt 16:03, 21 November 2005 (UTC)
Shouldn't we have an article on this topic? —Keenan Pepper 17:54, 22 November 2005 (UTC)

[edit] Pit M1 against M3?

The M3 Lee is a World War II tank with a 51 mm front armor made of ordinary steel. If a modern M1A2 tank fires a round of 120 mm armour-piercing fin-stabilized discarding sabot (APFSDS) at it at close range, would the depleted uranium kinetic energy penetrator fly straight through it from head to tail?

Since the M3's steel armor is not too slanted, the effective thickness of armor cannot be too thick. I think many modern penetrator can easily 500 mm.

Then how about a 75 mm thick M4 Sherman or an 180 mm thick Patton tank if you only have steel plates?

Can several modern tanks sink a heavily armored WW2 main battleship if the ship stays within their effective firing range? I mean you can aim at a point slightly below its water line. And if a tank cannot destroy all watertight compartments, several tanks may carry the required amount of ammunition. -- Toytoy 16:56, 21 November 2005 (UTC)

IIRC, velocity tends to decrease rather sharply (even if it is only one or two feet) after entering the water, ironically high powered weapons suffer this even more, unless it is equipped to travel through water, such as a tank-fired torpedo? :D. -- Natalinasmpf 23:04, 21 November 2005 (UTC)

I guess not either. The penetrator will bounce once it hits water surface. All you can do is to shoot anywhere above waterline but that's not too harmful. Even if the penetrator could penetrate below waterline hull, the 2-3 cm diameter and its also small fins does not punch a big hole. If you don't use depleted uranium that burns when it hits target, a small clean-cut hole with low water pressure can be repaired by trained sailors in minutes. Even if you have a dozen tanks firing at a battleship at will, you may not do too much damage.
For your information, as far as I know, depleted uranium does not burn when it hits a target. You may be thinking of that other controversial weapon, white phosphorous. DJ Clayworth 16:55, 22 November 2005 (UTC)
Ship hulls have at least two spaced layers. Even if you managed to punch multiple holes below waterline to a single water-tight compartment, the filled water would easily stop further damage by making the penetrators unable to hit the other wall. -- Toytoy 00:40, 22 November 2005 (UTC)
Unless the ship in question is the Exxon Valdez, in which case a single hull is deemed to be sufficient. StuRat 17:03, 22 November 2005 (UTC)
All of those answers neglect the fact that if the battleship was within range of the tank, then the tank is well within range of the battleship. And it wouldn't even need to actually hit the tank. Rmhermen 06:32, 26 November 2005 (UTC)

[edit] Scanning and filing recipes

Hi —

I've got a huge stack of NYT (& other) recipes clipped from newspapers. Now this stack is rather unweildy. Does anyone know of any software which I could use to scan the recipes in and then 1) convert the image to text, and 2) be able to recognize ingredients or keywords and allow the creation of a searchable index?

I know that 1 exists (anyone know of open-source/freeware, though?), but no idea about 2.

Thanks! — Asbestos | Talk (RFC) 17:24, 21 November 2005 (UTC)

I believe most scanners comes with their own OCR (Optical Character Recognition) software, so you could use that for free. With newspaper clippings, you will need to be careful in adjusting the threshold to avoid "bleed thru" from the other side of the page, which will throw off the OCR software. The indexing is a more difficult issue. Just looking for keywords doesn't work very well. If you've used a Google search you see how many unrelated things are found in any search. For eggsample, if you were trying to list "egg dishes" as a category, you would also get things which are not egg dishes, but only contain small amounts of egg as part of the recipe. I think you would do better to manually index and categorize them, say by dragging them into folders for each type of recipe, and then adding indexes for other ways to organize recips, like low-fat, low-carbs, low-protein (for those cult leaders interested in brainwashing their followers), etc. StuRat 18:37, 21 November 2005 (UTC)
GOCR is an open-source OCR program. –Mysid 08:01, 22 November 2005 (UTC)

Thank you both! I'm taking a look at JOCR now. — Asbestos | Talk (RFC) 15:48, 22 November 2005 (UTC)

[edit] November 22

[edit] White Opossums

A reader in Memphis, Tennessee sent the following question to the help desk.

I spotted a WHITE opossum last night in my back yard. I do have a picture (happy to send if you want) of it (it came up to my sliding glass back door) and it is fully white, not a speck of grey, brown or black on it. Is this a common color for some opossums? I don't think it is but wanted to ask.

Any help you can give him would be greatly appreciated.

Capitalistroadster 02:41, 22 November 2005 (UTC)

[edit] Questions about T-rex blood

Another question to all you scientist wikipedians, or anyone who has a clue what this might mean:

It is debated whether T. rex was warm or cold blooded, and no definitive evidence exists to disprove either argument. Opinion may favor the dinosaur being homeothermic (warm-blooded), although probably not as warm blooded as modern mammals. There is some speculation that the creature's homeothermic strategy might have changed at times in its life cycle.

Specificly,

Opinion may favor the dinosaur being homeothermic (warm-blooded), although probably not as warm blooded as modern mammals.

Animals are either cold or warm blooded with no inbetween, right?

and

The Tyrannosaurus rex's homeothermic strategy might have changed at times in its life cycle.

What is a homeothermic strategy and how might it change?

Thanks everyone.

WikifunBanana04131 04:01, 23 November 2005 (UTC)

There do seem to be some "in-between" states, and in the past there may have been far more. Warm-blooded animals (including us) could not have evolved from cold-blooded animals without there having been some intermediate steps in the process. I've often though that if you could combine a warm-blooded animal's ability to control it's body temperature with a cold-blooded animal's ability to withstand variations in blood temperatures, then you would really have a good combo. I'm not sure why this never evolved. StuRat 02:03, 24 November 2005 (UTC)
Also note that many current warm-blooded animals change their strategy for thermal control during their life-cycle. That is, babies are frequently incapable of keeping themselves warm, and must stay near a warm object, typically their mother, to keep alive. Adults are able to keep themselves warm. StuRat 02:07, 24 November 2005 (UTC)
Thanks! Banana04131 17:41, 24 November 2005 (UTC)

[edit] Hydrolosis

Why does hydrolosis of starch take longer than hydrolysis of sucrose? --69.165.33.225 05:35, 22 November 2005 (UTC)

I am not a chemist, but my guess would be that it's because starch is insoluble in water, whereas sucrose is soluble. So the starch will not dissolve, leaving it in larger clumps with low surface area, but the sucrose would dissolve, vastly increasing its surface area and making it easier for hydrolysis to occur. —HorsePunchKid→龜 2005-10-22 06:13:33Z

The solubility is the principal property but there are a couple of others. #Starch has twice as many bonds to be hydrolyzed. Sucrose has only single bond connecting a glucose and fructose (ratio of moieties to bonds 2:1), while starch is chains of glucose (ratio of moieties to bonds, nearly 1:1).

  1. Starch strands are branched, with 3 glucose moieties attached to a single one at numerous points in the chain. This further reduces access by hydrolyzing agents.alteripse 12:16, 22 November 2005 (UTC)

[edit] The pills that the Goebbel children took

Greetings:

Does anyone know of the name of the pills that Mrs. Goebbel forced her children to bite in "Der Untergang"? It seems like such a quick and painless death. I would like to know where I can buy them so that I could use them in times of need.

Regards,

129.97.252.63 05:55, 22 November 2005 (UTC)

I didn't see the film, but it seems that at this point the director had to take some liberties, because it is not certain how Magda Goebbels killed her children; according to the German Wikipedia she most likely gave them cacao with some kind of barbiturate, which would not lead to a very speedy death, I think. Our article says she first put them to sleep with morphine and then fed them cyanide, which kills quickly but not without pains and convulsions. Maybe it's better to live. David Sneek 07:27, 22 November 2005 (UTC)
A quick and painless death is something of an oxymoron in toxicology: you can have quick or you can have painless, but not both. Cleopatra is said to have conducted numerous experiments on prisoners before choosing asp venom as her means of suicide. Physchim62 (talk) 07:49, 22 November 2005 (UTC)
The asp is a viper, related to the adder, but a bit more poisonous. Very uncomfortable, not always fatal. I have read suggestions that she actually would have used a cobra. Notinasnaid 10:37, 22 November 2005 (UTC)
Yea, killing yourself that way sound like a real pain in the asp. StuRat 03:09, 23 November 2005 (UTC)

Who are you planning to kill? Can we put your name on file with your local police? That's the basic problem with deadly weapons. alteripse 12:08, 22 November 2005 (UTC)

"The National Librarians Association has moved to have the how-to suicide book, Final Exit, banned from their shelves...not because they object to the contents, per se, but because nobody who checks out the book ever seems to return it." StuRat 03:09, 23 November 2005 (UTC)
Résumé
Razors pain you;
Rivers are damp;
Acids stain you;
And drugs cause cramp.
Guns aren't lawful;
Nooses give;
Gas smells awful;
You might as well live.
- Dorothy Parker
In practical terms, a suicide pill that is painful but quick seems ideal. It wouldn't be an obstacle when you really did need it (e.g. painful terminal disease with no prospect of pain relief, civilisation collapsed and food ran out); but it would be a deterrent for ordinary depression (death of cat, threat of bankruptcy...) Notinasnaid 10:47, 23 November 2005 (UTC)
Sounds a lot like Drion's pill --WS 20:06, 24 November 2005 (UTC)

so touched, maybe i'll not kill myself after all. 129.97.252.63 19:41, 28 November 2005 (UTC)

[edit] Biochemistry question

How would I arrange these terms from least to greatest by "representative size"?:

I assume the atom would be the smallest, and the disaccaride quite large, but I'm abysmal at biochemistry. Can anyone lend a hand? Neutralitytalk 05:59, 22 November 2005 (UTC)

Does "representative size" have some concrete definition in biochemistry? All I could think is that they're asking for the typical molecular weight, though obviously in the case of proteins and such, that can vary a lot. Here's roughly what I'd guess in that case, though you'll probably need to research each one to get an accurate weight:
  1. carbon atom (element, very small)
  2. carboxylic acid (simple acid, pretty small still)
  3. disaccharide (just about the simplest sugar you can have)
  4. triglyceride (big but simple fatty acid)
  5. protein (can be huge)
Hope that helps! —HorsePunchKid→龜 2005-10-22 06:08:13Z

[edit] Getting sound on Debian Linux

I'm new to Linux, and I love it, except for the fact that I can't get sound to work. I tried Google and tried one website's solution, but it didn't work for some reason. I'm running GNOME desktop environment on a Dell Latitude D810, if that helps. If there's anything more you need me to tell you, just ask. I really miss being able to listen to CDs, so any help you huys can offer would be great. Thanks in advance!

One place you might get some instant feedback help is #debian on irc.debian.org. Be warned, they're sometimes a little less polite than you might hope.
Things to check first. Type "gnome-volume-control" at the command line and see whether your soundcard has been detected (and if so, what chipset it is). If it's been detected, turn the volume up on the CD channel (I know this sounds insulting but some people forget to check). If not, run the "lspci" command to find out what's actually in your computer.
One other important question people will want to know is what version of Debian you're running, and whether you have a custom kernel. --Robert Merkel 06:17, 22 November 2005 (UTC)
Make sure you have ALSA correctly installed and configured. --Oldak Quill 15:54, 22 November 2005 (UTC)

Okay, I tried gnome-volume-control, and it popped up a window that said "Sorry, no mixer elements and/or devices found." Does this mean my sound card isn't detected? Amd if so, how can I get the system to detect it?

I have the latest stable version of Debian, at least as far as I know, but I don't know where I'd be able to find more specifics about the release. I haven't customized the kernel myself.

I installed ALSA but I'm not sure if it's correctly configured. How would I go about doing that?

Sorry for asking so many questions, and sorry if these questions are really stupid! Thanks again!

I used to have all sorts of problems with sound on my Mac laptop running SuSE. That's not your configuration, I know, but some of the same things I tried may help. I discovered that I had to do two or three out of the following:
  1. walk through a non-default "configure sound card" screen during installation (i.e. initial clean install of Linux), and adjust master volume
  2. walk through a "configure sound card" screen from the system maintenance tool, and adjust master volume
  3. adjust the "sound" line in /etc/modules.conf
  4. run "alsamixer" and adjust the master and "beep" volumes
Sorry I can't be more precise here. I think either 1 or 2 takes care of 3; I didn't have to do 3 the last couple of times I reinstalled.
But I definitely had to play with alsamixer too. Steve Summit (talk) 23:57, 22 November 2005 (UTC)

[edit] biology

Hope you can help me. Here is my question? _____________________ is the change within a population. Some individuals within this population possess certain characteristics/adaptations and those will produce more offspring?

I need to know the word meaning in the blank above. Thank you Mike

Do you think this might be less obvious as a homework question if you rephrased the question in your own words? Have you checked out the population genetics pages on the web? David D. (Talk) 07:06, 22 November 2005 (UTC)
I think the reason the question is unintelligible is that our inquirer did rephrase the question in his own words. I am inclined to ask for a more faithful rendering of the question if he wants us to venture an answer. alteripse 16:37, 22 November 2005 (UTC)
My first guess would either be "mutation" or "variation". Of course, the problem is to think about what words the teacher is likely to use and uses most often, ie. what are his or her favourite words to describe something? ;-) -- Natalinasmpf 17:53, 22 November 2005 (UTC)
"Selective advantage", I think, is more like what's being asked for. Fill-in-the-blank questions are probably better for training Gellers and Kreskins than scientists.... - Nunh-huh 00:14, 23 November 2005 (UTC) P.S. Like, o-mi-gosh, could the elusive like, word, be "evolution"?! It would help to know if this was meant to reflect a grammar school or high school understanding of the subject. - Nunh-huh 00:17, 23 November 2005 (UTC)

Mike here actualy this was a biology test question and none of your sugestions are right from the answer given! so this is not a homework question just trying to get some clarification on the question listed above.. thanks mike

Are you looking for natural selection or positive selection (which are reasonably good answers, I think) or genetic drift (not as good an answer, but the first that occurred to me), or should it be a one-word answer?-gadfium 07:40, 23 November 2005 (UTC)

[edit] Need help about pig's behaviour

Hi!I'm Anne, i need some information about pig's natural behaviour. Actually i do my research on that. Please help me.Thank you

With regard to pig's natural behaviour I would have thought a google search would be pretty productive. David D. (Talk) 07:54, 22 November 2005 (UTC)

[edit] Pentaped

I learned a new word on a television show about Chupacabras. Are their any real animals that are pentapeds?

  • See Chupacabra - 131.211.210.16 09:32, 22 November 2005 (UTC)
  • Starfish. alteripse 12:00, 22 November 2005 (UTC)
    • Strictly speaking, the arms of a startfish are not legs: they do not support the rest of the body above the ground, and they are not used for locomotion. However, to answer you dear user, no. Because all terrestrial animals that possess true legs also have bilateral symmetry, they all have a number of legs that are multiples of 2 (2, 4, 8, 12, 100, etc). – ClockworkSoul 07:33, 25 November 2005 (UTC)

[edit] graph theory

What is the maximum number of vertices in a graph with 15 edges and three components? It's 18 isn't it? Cos each component has at most n+1 edges if n is the number of vertices --Dangherous 14:34, 22 November 2005 (UTC)

  • Sounds right to me if you swap the words edges and vertices in your last sentence. Bovlb 15:31, 22 November 2005 (UTC)

[edit] what can macromedia director do for me?

Ask not what Macromedia Director can do for you—ask what you can do for Macromedia Director. — Knowledge Seeker দ 07:41, 25 November 2005 (UTC)

Joking aside, Macromedia Director makes media files such as movies and Shockwave files. See the Macromedia Director article for more information. — Knowledge Seeker দ 07:42, 25 November 2005 (UTC)

[edit] Blood Type and Food Compatibility

My mom recently purchased a book by an author named Peter D'Adamo, a doctor who from what I gather alleges that people with certain blood types can't eat certain foods, or at least shouldn't. Is there any truth to this claim? It seems a little weird to me that someone with B blood type can't eat chicken or tomatoes, for example, and was hoping someone with medical knowledge could help me. --Impaciente 16:55, 22 November 2005 (UTC)

We have an article on the blood type diet (which I'm working on improving — thanks for reminding me). I personally think it's a bunch of quackery, but he has a lot of followers... so learn the facts and decide for yourself, I guess. —Keenan Pepper 18:02, 22 November 2005 (UTC)
I could possibly believe a statement like "people with blood type B have a higher incidence of allergic reactions to chicken and tomato products", but a blanket statement that "all people with blood type B should avoid chicken and tomatoes" sounds like pure quakery to me. StuRat 18:05, 22 November 2005 (UTC)
I wouldn't put too much faith in what one doctor says, as it's easy to find a doctor willing to say anything, if it gets him a truck load of money. You should look at whether it is accepted medical fact, as published in reputable medical journals like The Lancet, The New England Journal of Medicine, and the Journal of the American Medical Association. Pretty much anything you find in a "diet book" will be total crap, designed to enrich the author rather than improve the health of the reader. StuRat
Wikipedia does not offer medical advice–see our medical disclaimer–but just between you and me...yeah, it's nonsense. If you believe you have specific food sensitivities, contact your physician, allergist, or a nutritionist. StuRat above makes some excellent points. TenOfAllTrades(talk) 18:18, 22 November 2005 (UTC)

Quack, quack, quack. Crap, crap, crap. It is based on such egregious misunderstandings of population genetics, biology, and cell surface antigens I can't believe he would put his name on it, but he proves once again you cannot, repeat cannot, overestimate the gullibility and ignorance of the American public, and no matter how stupid your theory, if you can keep a straight face while you say it, someone will buy it. alteripse 00:27, 23 November 2005 (UTC)

Has any other independant research claimed that blood types evolved as he claims? The blood type article says nothing. The whole idea just seems rubbish. Still, if the diet encourages people to check their blood type, and from there go on to give blood, that must be a good thing. smurrayinchester(User), (Talk) 08:13, 23 November 2005 (UTC)
Of course no one has "independently" supported his fantasies with evidence, and he is not a medical doctor. This diet makes as much sense and has as much science behind it as "eat right 4 your astrological sign." Giving blood is a way of finding out your blood type if you are curious, but the idea that it indicates whether you are descended from an isolated tribe of farmers or hunters is indeed rubbish. alteripse 12:33, 23 November 2005 (UTC)

[edit] speed of light and time?

Hi. I would like to get an answer to something that has been bothering me. I know that as a suposed ship reaches closer and closer to the speed of light that time slows down for thoses on the ship. Could someone plesae explain to me the cause and effect of this. thanks for your time, Tim.

See time dilation and Special relativity. TenOfAllTrades(talk) 18:03, 22 November 2005 (UTC)
The fundamental premise of special relativity is that the laws of physics are always the same no matter how fast or in what direction you're moving, and in fact there's no way to tell how fast you're moving unless you have something "standing still" for comparison. So, the people on your spaceship would not notice anything different no matter how close they got to the speed of light, except in relation to other things that weren't moving along with them. For example, if they were talking to mission control back on Earth by radio, they would notice the replies taking longer and longer to come back (and the radio signals would be redshifted). Also, if they turned around and came back to Earth, more time would have passed on Earth than on the spaceship — this is the twin paradox. —Keenan Pepper 18:25, 22 November 2005 (UTC)


[edit] COMPUTER HELP ME

  What is the storage location and adress (computer related)

The location in memory where a byte of information is stored is described by a number (the address of that memory location). For example, if your name was stored in the computer, it could be written at the very beginning of memory, which would be bit 1 (or bit 0, if they start counting at 0 instead of 1, as they often do in computers). Depending on the length of your name, the next available address in memory might be, say, 30 bytes later. Note that they tend to use hexadecimal numbering, with leading zeroes, to describe memory addresses, as shown below. Thus the next address in memory might be 000000001E:

Decimal  Hexadecimal
=======  ===========
   0      0000000000 
   1      0000000001 
   2      0000000002 
   3      0000000003 
   4      0000000004 
   5      0000000005 
   6      0000000006 
   7      0000000007 
   8      0000000008 
   9      0000000009 
  10      000000000A 
  11      000000000B 
  12      000000000C 
  13      000000000D 
  14      000000000E 
  15      000000000F 
  16      0000000010 
  17      0000000011
  18      0000000012
  19      0000000013
  20      0000000014 
  21      0000000015 
  22      0000000016 
  23      0000000017 
  24      0000000018 
  25      0000000019 
  26      000000001A 
  27      000000001B 
  28      000000001C
  29      000000001D
  30      000000001E

Another form of memory address is memory offsets (relative addresses) where the amount to add to a fixed reference address is given, rather than the absolute address. Virtual memory takes this further, and uses a program that figures out where to actually store the data, regardless of the memory address you specify. It uses a look-up table to match the addresses you specify with the real addresses. In most modern programming languages you can, but don't need to, specify memory addresses. Whenever you declare and assign a variable, like X=5, the system figures out a place to store that automatically. The most common place a user will see an address is in an error message, something like "Memory overflow at address...". StuRat 19:35, 22 November 2005 (UTC)

[edit] CD-R storage

I'm trying to back up my digital photos on CD-Rs. The .jpg files average about 1.4 MB in size. The capacity of the CD-Rs is 700 MB, thus I figure I should be able to fit 500 photos on a disk. However, I'm finding that I can only get about 400 before I run into "disk full" error messages. Furthermore, after I copy only a few files to the CD I sometimes get the "disk full" message. If I take the CD out and place it back in the drive, this message goes away. What's going on? (I use Windows XP)

The internal CD-writer application that's built into Windows XP will cache the files you wish to burn in a temporary directory. I suspect you're running out of space on the harddrive, and that's why you're getting the errors.
If you have a stand-alone burning application, you should be able to use that one. --Pidgeot (t) (c) (e) 19:25, 22 November 2005 (UTC)

[edit] Why dont lamps and other devices need adapters?

The way consumer electronics do?

Assuming you mean an incandescent lamp, "getting something hot enough to glow" isn't a very precise operation. By adjusting the filament length and thickness, you can make a wide range of voltages and amperages cause it to glow, so no adjustment is needed. However, if you take a lamp to other countries, an adapter may be needed, or you may get a dim light or burn it out quickly. StuRat 23:05, 22 November 2005 (UTC)
There is also the issue of alternating current and direct current. The electric potential in the wall is constantly changing polarity. This makes no difference to a light bulb or some other heat-generating device, since the lightbulb will heat up regardless of the direction of the current. Most electronic devices require direct current, cince circuitry involves transistors, which heavily depend on the direction of the potential across them, and so a transformer is needed to rectify the current as much as to lower the voltage (lowering the voltage decreases the quantity of heat generated by the electronics). --Borbrav 02:51, 23 November 2005 (UTC)
Ah! I get it now. "Adapters" made me, as well as StuRat, think of the kind that you use for almost anything electrical when you travel to a foreign country with different electrical standards, and a lamp would need one of those if yo traveled with it. But the question was really about wall warts. So the basic answer is that lamps don't need an adapter because they are designed to take the same voltage that your outlet supplies -- unlike electronics which, for the reasons Borbrav explains, require a lower voltage and it has to be DC.
Electronic appliances that don't use an adapter, like televisions and computers, have similar components internally. See also power supply.
--Anonymous, 10:00 UTC, November 23, 2005

People rarely take light bulbs with them overseas, but yes, they in theory need adapters. 153.111.60.15 07:36, 24 November 2005 (UTC)

[edit] Availability of the DSM-IV (diagnostic and statistical manual of mental disorders)?

Is the DSM available to the general public, or do you need to obtain it from the APA? Would you need to be a qualified psychologist/psychiatrist in order to obtain it this way? Is there an online reference available?

Yes, DSM-IV is publically available. You can buy a new version for $67.72 plus shipping on Amazon.com [52], and it is probably available at your local bookstore or library. Neutralitytalk 23:24, 22 November 2005 (UTC)

[edit] November 23

[edit] Science

What product is produced when carbon deoxide reacts with iron?

I'm not sure if carbon dioxide actually reacts with iron directly. What conditions is the reaction taking place? Is this question related to transition metal chemistry? --HappyCamper 01:40, 23 November 2005 (UTC)
Yeah I'm pretty sure they'll just sit there. How do you propose to make them react? —Keenan Pepper 01:42, 23 November 2005 (UTC)
Ah! Maybe this, where the iron acts as a catalyst and not as a reactant? [53]. Looks like you get some nifty hydrocarbons. Would be neat to find the publication. --HappyCamper 01:55, 23 November 2005 (UTC)
At the right temperature, iron will reduce carbon dioxide to carbon monoxide (I've not got the data with me to construct the Ellingham diagram, so I can't give you the exact temperature range). At room temperature, the reaction is so slow as to be negligible. Physchim62 (talk) 09:39, 24 November 2005 (UTC)
According to this article, iron can be used at a catalyst to convert CO2 into longer hydrocarbons at 300°C at 100 times atmospheric pressure. I can't find any conditions under which iron would actually react with CO2. Basically, although iron really likes to be oxidized, it won't readily be reduced, which is what a reaction with CO2 would constitute. – ClockworkSoul 07:50, 25 November 2005 (UTC)

[edit] Maths

If I roll two dice and I always pick the higher number (of the two dice results). Which number is the most often picked number? {1,2,3,4,5,6} Ohanian 01:46, 23 November 2005 (UTC)

Well, you have a 6 by 6 table of outcomes. 11 of those give you 6, 9 of those give you 5, 7 of those give you 4, 5 of those give you 3, 3 of those give you 2, and 1 of those gives you 1, so 6 would be the most common, with a probability of 13/36. As a sidenote, there is a very interesting pattern in those numbers of outcomes-they are all equal to 2*n-1, where n is the result of the roll. --Borbrav 02:45, 23 November 2005 (UTC)
Here's a table showing all the possible outcomes. Clearly 6 wins over everything but itself, and 1 loses to everything but itself.
MAX 1 2 3 4 5 6
1 1 2 3 4 5 6
2 2 2 3 4 5 6
3 3 3 3 4 5 6
4 4 4 4 4 5 6
5 5 5 5 5 5 6
6 6 6 6 6 6 6
Is this gambling or homework? ;-) —KSmrqT 21:31, 23 November 2005 (UTC)

Neither, it's a role-playing game. Ohanian 04:13, 25 November 2005 (UTC)

As KSmrq explains, 6 is the mode, which is what you asked; the mean would be about 4.5 - Nunh-huh 07:47, 26 November 2005 (UTC)

[edit] Preparing for zoology lab exam

Greetings:

In preparation for my zoology lab exam (which consists of slides of photographs taken of specimens from real labs and the professor pointing to different parts of the photograph and we write on paper the names of the parts and their functions), I am looking for books or online resources that contain labeled colored photo micrographs of the various bodyparts and life stages of the following microscopic animals:

  • amoeba, peranema, trypanosoma
  • monocystis, plasmodium, vorticella
  • obelia, hydra, aurelia, metridium
  • turbellaria, trematoda, cestoda

Please note that I'd like pictures of the real thing instead of mere schematics, which my lab manual is full of and won't help a lot on a real-photo lab exam. If anyone have any books or resources to recommend I would appreciate it very much.

Thank you.

129.97.252.63 03:28, 23 November 2005 (UTC)

Hmm... let's see, maybe wikification of these articles will result in links to articles with pictures...
Maybe commons and wikisource has stuff too. Check out [54] and [55]. Come back in a little bit and see if other Wikipedians can provide better resources for you. --HappyCamper 03:32, 23 November 2005 (UTC)
Related articles: vorticella is a peritrich (Google: [56])
Monocystis appears here. (actually, why not use a Google image search, like this.
metridium
peranema, a Euglenid- Nunh-huh 03:58, 23 November 2005 (UTC)

Google images. One of the best resources there is. 153.111.60.15 07:39, 24 November 2005 (UTC)

[edit] Pointy ears

Is there a heritable trait that causes pointy ears in humans? (And I'm not talking about Williams syndrome or Donohue syndrome). Is it common in human populations to have people with pointy ears? (As opposed to elven populations, heh.) Any statistics on number per how many live births, that sort of thing? Thanks. -- Миборовский U|T|C|E|Chugoku Banzai! 05:52, 23 November 2005 (UTC)

[edit] How to simplify a calculation in Excel?

How do I simply a calculation like this:

  • Column A: Date 1
  • Column B: Date 2
  • Column C: = MAX (Date 1, Date 2) + 10 days

So far, I only know this method which is very clumsy:

DATE (YEAR (MAX (A1, B1)), MONTH (MAX (A1, B1)), DAY (MAX (A1, B1) + 10))

Is there a method to simplify the calculation other than adding an additional Column D which is MAX(Date 1, Date 2)? -- Toytoy 08:55, 23 November 2005 (UTC)

Umm, max(date 1, date2)+10 seems to work fine in Excel 2002 (running under Windows). I have
01/01/2005 in A1
03/01/2005 in B1
=MAX(A1,B1)+10 in C1
and C1 displays 13/01/2005 (these are all DD/MM/YYYY dates). If you see a 5 digit number in your results cell, right click on the cell, select Format Cells, and in the Number tab change the format to Date. Excel stores dates internally as the number of days since 1/1/1900, so 13/01/2005, for example, is stored as 38365, and will display as 38365 if Excel does not realise that the cell holds a date, not a number. Gandalf61 10:31, 23 November 2005 (UTC)
I think it's not possible to do that with months or years. Can I setup an internal variable within a formula? -- Toytoy 12:58, 23 November 2005 (UTC)

[edit] Bombs & explosives

Does anybody know the main ingredients that are in the bombs utilised by suicide bombers? For example, is it TNT, dynamite, or whatever? Likewise, what materials are in time-bombs? And what makes a bomb more powerful than others?

TNT (which is commonly used in dynamite) is not the norm. It is hard to make. Instead, you just take a year or two of chemistry and learn that some molecules have too many electrons and others don't have enough. Sometimes a molecule is barely getting by with the electrons it has and a better atom shows up. Putting them near each other will make weak bonds break and strong ones join together - releasing heat. If oxygen is released while that happens, you get a very rapid expansion of gas - usually referred to as an explosion. Wrap all of this in little metal or lead pellets and you have a grenade. Wrap a huge grenade around an idiot and you have a suicide bomber.
In case you think that chemistry is for stupid geeks, try mixing different toilet bowl cleaners. It shouldn't take you too long to realize that you need to do a little studying. --Kainaw (talk) 14:15, 23 November 2005 (UTC)
See our article on explosive materials. Oh, and do not try this at home—there are a lot of explosives chemists who are short fingers and/or eyes.

TenOfAllTrades(talk) 15:35, 23 November 2005 (UTC) It's kind of hypocritical too, fundamentalists are people who usually hate science. ;-) Or maybe I play too much Sid Meier's Alpha Centauri. -- Natalinasmpf 19:04, 23 November 2005 (UTC)

For example, according to news reports, the supposed aspiring terrorists arrested in Australia were alleged to be attempting to make the explosive TATP. I believe this is a relatively common one for terrorists to try. --Robert Merkel 01:30, 24 November 2005 (UTC)
That was also the explosive used in the 7 July 2005 London bombings, which shows that terrorists don't know that much chemistry... (Aum Shinrikyo being a notable exception) Physchim62 (talk) 09:44, 24 November 2005 (UTC)

[edit] Lactose intolerance in other mammals

After reading the article on lactose intolerance, I had one question that kept popping up - what about other mammals? In humans, there is apparently a regional genetic mutation that allows some of us (mostly European Caucasians) to digest/metabolise lactose into adulthood, while most mammals lose that ability at a certain stage of adulthood. What about some mammals that seem to continue to drink milk into adulthood - most obvious example, cats? Does the common housecat have the same genetic mutation, or it is something completely different? — QuantumEleven | (talk) 14:11, 23 November 2005 (UTC)

Actually, cats don't typically drink milk into adulthood. Like most other adult mammals, adult cats are lactose intolerant because of low or absent lactase. Feeding cow's milk to most adult cats will cause diarrhea, which is why there are low-lactose/no-lactose milk products available for pets. I've also heard stories of folks feeding their cats cow's milk mixed with yogurt without any symptoms of lactose intolerance. Presumably this is because the bacteria in yogurt produce lactase that can help with the digestion of lactose. --David Iberri (talk) 22:09, 23 November 2005 (UTC)
So all the stories about giving cats a saucer of milk only apply to kittens, or using special low-/no-lactose milk? (No, I don't own a cat, I was just curious). — QuantumEleven | (talk) 08:39, 24 November 2005 (UTC)

All cats I've known like milk; but because it gives them diarrhea it's better to dilute it with water. David Sneek 13:47, 24 November 2005 (UTC)

[edit] Micrograph books

Greetings:

Are there any books that contains photo shots of microscope viewings of microscopic organisms such as protista, cnidaria, and platyhelminthes? In other words, I'm looking for "A Photographic Atlas for the Zoology Laboratory" equivalent for the microscopic animals such as protista, cnidaria and platyhelminthes.

Regards,

129.97.252.63 16:17, 23 November 2005 (UTC)

[edit] Rabies - first reported in native americans

I am interested in the first reports of rabies observed by native americans (human or animal). When, where, and what species involved. Any medicinal remedies used? Thanks, Ernest Oertli Zoonosis Control Group Texas Dept of State Health Services <e-mail removed>

I found [57] which you might find useful...Also, perhaps contact the Government of Ontario, who prepared this synopsis: [58]. It may be necessary to redefine the scope of your question so that only documented/substantiated cases are considered. --HappyCamper 03:04, 25 November 2005 (UTC)

[edit] venus

how long is time of flight from earth to venus?also what could we expect to find on venus surface? --curious venus researcher

The minimum distance between the Earth and Venus is about 40 million kilometers. At the speed of light, that would take a shade over two minutes. Any other times of flight would be longer. A minimum-fuel Hohmann transfer orbit would take 146 days. See also our article on interplanetary travel.
For information about Venus itself, see Venus. TenOfAllTrades(talk) 17:15, 23 November 2005 (UTC)

[edit] Sodium Carbonate as a Stain Remover

How does sodium carbonate remove stains from laundry?

For example, an oil stained piece of clothing is soaked in a solution of sodium carbonate and water. Thanks--Curious Person

Hm...sodium carbonate–which also goes by the common name washing soda–is usually used as an additive or supplement to detergents rather than by itself. It softens water by binding to dissolved calcium and magnesium—in hard water detergent molecules tend to bind to those dissolved metals instead of to oil and dirt. Sodium carbonate is also a weak base; in some cases this can increase the solubility of stains in the wash water, removing them from clothing.
One other thought occurs to me—is it possible that you're dealing with sodium percarbonate? When dissolved in water, this compound releases sodium carbonate (giving the softening and alkalinity benefits mentioned earlier) and hydrogen peroxide which can attack and bleach stains. TenOfAllTrades(talk) 17:00, 23 November 2005 (UTC)
Wow! It's been such a long time since I've even heard of this compound...ah...the good old days! Anyway, I agree, the release of peroxide seems to be the likely answer. --HappyCamper 02:20, 24 November 2005 (UTC)

Why Did Sodium Carbonate (Washing Soda) Dissolve an Oil Stain Thank you for your prompt answer concerning Sodium Carbonate as a stain remover ( "Arm and Hammer's Washing Soda" was used to remove an oil stain without detergent, just soaked in hot water and Arm and Hammer).

The answer mentioned that ..."It softens water by binding to dissolved calcium and magnesium—in hard water detergent molecules tend to bind to those dissolved metals instead of to oil and dirt. Sodium carbonate is also a weak base; in some cases this can increase the solubility of stains in the wash water, removing them from clothing..."

If the water was "soft," and the water did not have to be be softened by binding to as many dissolved calcium and magnesium molecules, would the base of sodium carbonate be able to attack the stain by increasing the solubility of the stain since it was not softening the water as much.

Thanks again. --Curious Person

[edit] Zoology sites

Greetings:

Does anyone know of any university website that offers a comprehensive photo repository for zoology class labs like the University of Wisconsin site here?

Regards,

129.97.252.63 17:47, 23 November 2005 (UTC)

[edit] Slow ip?

What do you call an ip that rotates once a month?? ie, too slow to be a dynamic ip, yet too mobile to be a static ip? does it have a name, or something? thnx?--Ip ano n 18:21, 23 November 2005 (UTC)

I thought the point of a static IP was that it always stayed the same, like, forever. So, even if an IP changed only every few years, it would still be a dynamic IP. —Keenan Pepper 18:50, 23 November 2005 (UTC)
No, that is not correct. The below answer is correct. It may not be a useful reference desk if people who don't know answers just guess wrong answers. -lethe talk 20:09, 23 November 2005 (UTC)
It is mostly correct: Since static IPs are assigned on the machine, they do not change unless the machine is explicitly reconfigured with a different one (which you usually don't do). The incorrectness purely arises due to lack of precision. --Pidgeot (t) (c) (e) 22:58, 23 November 2005 (UTC)
The difference between static and dynamic IPs is not the speed of change. A dynamic IP might be assigned to a machine once and stay there for years, until the machine is decomissioned. Some machines may change static IPs every few seconds. The difference is that a static IP is assigned to that machine specifically (this can be a manual or automatic process), while a machine with a dynamic IP never had an IP assigned to it. A dynamic IP address is obtained by asking on the network for one (typically, using a DHCP server). Notinasnaid 19:48, 23 November 2005 (UTC)
How could a machine change static IPs every few seconds? —Keenan Pepper 21:57, 23 November 2005 (UTC)
By being reconfigured every few seconds, either manually or through a script running in the background.
However, this is a highly unlikely scenario, as this largely defeats the purpose of configuring it in the first place. --Pidgeot (t) (c) (e) 22:58, 23 November 2005 (UTC)
The scenario I was thinking about is where several machines work to provide services collectively. I have set up "fail over" systems, where a machine would add an extra IP (remember, a machine may have many IPs) if it could no longer contact another machine. That provides a continuous service even after a failure. I could imagine machines working together as a pool, and changing the IPs that they offer to balance load around, very frequently. It would have to be a stateless protocol like UDP, rather than TCP/IP. These IPs would generally be considered "static" because DHCP wasn't in use. Notinasnaid 10:10, 24 November 2005 (UTC)
You assert your own IP, or something. I brought Knoppix to my school library once, which happens to not use DHCP; I was in a fix about how to get connection to the internet because DHCP wouldn't work - then I realised I could simply "assert" an IP as long as I knew the subnet and gateway and such - I don't know exactly how it works, but apparently it was a static system, but I could also go around and assert an existing IP; and with time that IP became "mine" (not immediately, but after a minute or so) since whatever (it became a funny prank, but I don't do that anymore) data got passed along to that IP came to my computer, not theirs, and the previous computer with that IP got disconnected. But it was a static system, you would basically assert a new static IP every few seconds. -- Natalinasmpf 22:56, 23 November 2005 (UTC)

[edit] Shrimp color

How come raw shrimp are almost clear, and they become red when cooked? Most organic pigments become oxidized and lose their color when heated, right? And other meats like beef start out red and turn brown when cooked, so it seems weird that shrimp (and some other seafood I think) become more red instead of less red. —Keenan Pepper 22:48, 23 November 2005 (UTC)

  • Fun question! Shrimpies and such have a pigment in them called astaxanthin. It's usually locked up in darker protein chains, but these unwind when cooked, making the red color visible. It has the function of protecting the roe from ultraviolet. It's also the same pink that salmon get after eating shellfish (or, in the case of the farmed ones, being fed the dye.) --jpgordon∇∆∇∆ 23:18, 23 November 2005 (UTC)
    • Is that mentioned in the shrimp article? - Mgm|(talk) 23:38, 23 November 2005 (UTC)
  • No, but it should be. --hydnjo talk 16:17, 24 November 2005 (UTC)
Flamingos cook their shrimps? Shantavira 16:56, 26 November 2005 (UTC)
      • Doesn't it have anything to with chitin polymerization?--172.129.241.116 02:47, 24 November 2005 (UTC)

[edit] Sky

Why is the sky blue?

Diffuse sky radiation. Blue light is scattered more than red light. This also explains why sunrise and sunset are orange and red — the blue light is scattered away and the other colors remain. —Keenan Pepper 23:15, 23 November 2005 (UTC)
Oh, in addition, one shouldn't forget that water (which no doubt the sky contains a lot of) has a very faint blue hue - this is evident in pools where the water builds up, and given lots of volume of sky... -- Natalinasmpf 23:41, 23 November 2005 (UTC)
As far as I know, that's not true—water looks pretty clear to me under most circumstances. Certainly this has no effect on the sky; it's Kennan's answer that's right. -- SCZenz 00:32, 24 November 2005 (UTC)
Uh, do see our water (molecule) article - it says it is slightly blue. The reference cites this as one of the reasons for the sky's colour. It's not the sole reason, either. [59] Then there's this. Air is slightly slightly blue, and hence, the sky is blue. This forms the basic cause. Then scattering comes into play on top of this. Water is clear under most circumstances yes; but a pool of it 3 metres deep? It's a very faint blue filter, but compounded together, becomes blue. The various gases that make up air are well, gaseous, and take even more layers, but if you add about thousands of metres of sky.... -- Natalinasmpf 00:49, 24 November 2005 (UTC)
That's fascinating, I didn't know that. Nevertheless, the scattering is far and away the dominant effect. "Why is the sky blue?" is a classic question on the Berkeley Physics Grad Student Preliminary Exams, and I know what the correct primary answer is. The eskimo.com page you link substantially exaggerates the statements made by the journal article it links to. -- SCZenz 04:09, 24 November 2005 (UTC)
The scattering is the dominant effect, not the water. The spectra of the blue sky cannot be explained by the other mechanisms very well. --HappyCamper 02:17, 24 November 2005 (UTC)
I have no idea on that, but I would think the more complex phenomena is by scattering; the basic colour would be the air, which the scattering would account for the "smoothness" and how the sun impacts the sky? I mean, the sky does maintain it's bluish hue well into the evening. -- Natalinasmpf 02:30, 24 November 2005 (UTC)
Yes, that would be intuitive, but is not quite the case....Ah, take a look at this: The sky is blue due to molecular light scattering, with neither tiny air-borne particles nor its small and variable content of gaseous water having significant effect. It's at the bottom of [60], and it references [61]. --HappyCamper 02:43, 24 November 2005 (UTC)

Ah! Yes... that explains why the sky on mars is blue.... must be the scattering of light? or all that water...--Eye 22:04, 24 November 2005 (UTC)

Buh, what? everybody knows the sky is orange
Rayleigh scattering doesn't seem to have been mentioned yet. Ojw 19:01, 26 November 2005 (UTC)

[edit] November 24

[edit] Science

Hi. I'm doing a project for science and our unit right now is heat. My partner and I have to research about easy bake ovens. First off, we have to discuss the kinetic molecular theory (KMT), temperature, and heat of the easy bake ovens in terms of Q=MC and/or energy for the phase changes. Next, we have to identify where the 3 heat transfers (radiation, conduction, and convection) occur during the process of using the easy bake oven, and then have to apply Newton's law of cooling (Q/T=K (T1-T2)) to it. Lastly, we have to apply the first and second law of thermodynamics to the easy bake oven. All in all, my question is if you could help me gather this information or direct me to some usefull sites of where i could find this information? Please and Thank you.

Wonderful!! First of all, check out our collection of articles kinetic molecular theory, ideal gas, Newton's law of cooling, first law of thermodynamics, second law of thermodynamics, heat transfer, conduction, convection, radiation...you get the idea. Search the keywords on Wikipedia first, and come back if you have more questions! (And please let us know what model you are using for the oven. I'd be quite interested to hear back from you myself.) --HappyCamper 03:15, 24 November 2005 (UTC)

[edit] Scientific Research

Can anyone tell me what is or what do you understand by scientific research?

Thanks:-)

Hm. Tried Scientific research yet? --Borbrav 05:17, 24 November 2005 (UTC)

Scientific research is trying to find something out about the material world that can be checked by or demonstrated to other people, while conscious of, and taking steps to minimize, getting the wrong answer due to chance or personal preference or perception. alteripse 11:44, 24 November 2005 (UTC)

[edit] A chemical when mixed with water produces heat?

I am a novice with chemistry, however, I am working on a project whereby I would like to identify a chemical or combination of chemical substances that when combined (mixed) with water will generate a chemical exothermic reaction that will produce extreme heat up to 661 degrees centigrade (melting point of aluminium). Optimally, the process of this reaction would vaporize the reactants, leaving little or no trace elements of the chemicals used and / or the resulting residual chemicals are environmentally friendly (are not pollutants of water or air). And No, I am not building a bomb. The result I hope to achieve is to come up with a relatively inexpensive method of breaking the molecular bonds of a material that could be coated with this chemical substance. After coating the material, the introduction of water would create the desired reaction.

Potassium or any of the alkali metals would work, but if you're trying to generate extreme heat, burning something would be more effective, for example a bunsen burner. Could you clarify what sort of molecular bonds in which material are you trying to break? --Borbrav 06:42, 24 November 2005 (UTC)
It should be noted that the alkali metals will react with oxygen and water vapour in the air; chemists store pure alkali metals under oil to provent them from spontaneously oxidizing or igniting. TenOfAllTrades(talk) 00:37, 25 November 2005 (UTC)
What you are describing sounds almost like a type of specialized ideal liquid lithography. --HappyCamper 02:56, 25 November 2005 (UTC)
You maight want to take a look at phosphorus pentoxide: it reacts highly exothermically with water. I don't know if it gets up to 661 C, but it's a decent bet. – ClockworkSoul 07:16, 25 November 2005 (UTC)

[edit] Wikipedia Editors...

What do you do for a living?

Not edit Wikipedia, I can tell you that. Probably anything you can imagine—take a look under Category:Wikipedians by profession. -- SCZenz 08:05, 24 November 2005 (UTC)
Oh, cheers! As a programmer, I get the choice between Engineer and Geek according to that page. Ojw 18:53, 26 November 2005 (UTC)
I am a uni student, if you're interested. - Akamad 11:02, 24 November 2005 (UTC)
I am a civil servant, if you're interested (or even if you aren't). Thryduulf 14:34, 24 November 2005 (UTC)
I prefer to say that I do odd jobs for the French government (this sometimes involves teaching chemistry and physics). Physchim62 (talk) 15:15, 24 November 2005 (UTC)
I'm a doctor. You'll find a wide variety of careers here. — Knowledge Seeker দ 19:49, 24 November 2005 (UTC)
Graduate student/research assistant in a computer architecture group. Raul654 18:58, 26 November 2005 (UTC)

How long a list do you want? I'm a construction site manager and I use Wickie to take my mind off the stress of running a building site.--Eye 22:09, 24 November 2005 (UTC)

I imagine that most edits (at least the ones that take time) will come from unemployed people. Considering that I spend about 6 hours per day on Wikipedia (possibly more), I wonder how someone with a (full time) job could do that. Then again, most people will have a job, so I wonder which counts more, the quantity of those with a job or the time spent by those without one. I suppose retired people would be the best editors (time + knowledge), but older people will generally be less 'into' the Internet. Another aspect in which Wikipedia can still grow considerably. DirkvdM 11:29, 25 November 2005 (UTC)
Older people are catching up -- and "retired" doesn't mean decrepit! I'm exactly that -- a retired person with both time and knowledge to share. --jpgordon∇∆∇∆ 05:42, 26 November 2005 (UTC)
And thank you for that. I suppose you already understood me correctly, but I'd like to stress again that retired people are potentially the best resource for Wikipedia. It's just that generally (!), the older people are the less they will be active on the Internet. Over the next few decades that will change (and people from other parts of the world will also join in more). So considering how big Wikipedia aleady is (after a few years), it will be awesome in 20 years or so. The biggest organised collection of human knowledge ever. By far. And we're part of it. Doesn't that make us proud? DirkvdM 10:14, 26 November 2005 (UTC)

I'm a programmer. There's a retired astronomer doing the cosmology articles. Much of the math content is done by PhD postdocs (working as postdocs in academics) and by grad students in math/physics. linas 17:46, 28 November 2005 (UTC)

I'm a high school junior, but I'm applying to college this year because I hate living in Texas. --YixilTesiphon 05:32, 2 December 2005 (UTC)

[edit] Math in your head

hello I'd like to know if you could help me,... I'm particularly looking for daily math that can be done mentaly (in ones own head) any one out there can lend me a hand?- thanks in advance

The answer depends a lot on what math you know already, and what skills you're trying to develop. Let us know..! -- SCZenz 08:09, 24 November 2005 (UTC)
And what for? To exercise your mind? That would be a good advise to anyone. Do some calculations in your head regularly (at least one a day). You don't need to look for exercises though. Just do it in everyday life. Also, how much precision are you thinking of? I think it would greatly benefit mankind if pupils were taught to make good estimates of daily stuff in stead of just learning how to do exact calculation they will largely never use in everyday life (or even professionally). To mention one very extreme example, I recently heard someone on tv say that doomsday will be ten times worse than '9-11'. Getting an estimate wrong is one thing, but this is ridiculous. If democracy is to work, the people need to be able to make reasonable estimates of what is important, so that needs to be taught at schools.
Or were you thinking of something totally different? Ask a vague question and you can get just about any answer. :) DirkvdM 11:39, 25 November 2005 (UTC)
In the end, all math is done in one's head. Seriously. If you need the challenge, read a few pages of a math book (e.g. calculus), and then try to think about it in the shower or during a long walk. See how much you can remember. Try to do one of the homework problems in your head. linas 17:41, 28 November 2005 (UTC)

[edit] biology 2

Are all traits have only two genes?

No. Some have one (dominant) and some require several. alteripse 16:46, 24 November 2005 (UTC)

Why do you say two? Might you be thinking of the chromosomes being paired? In that case, only the X and Y chromosomes don't have base pairs. (I'm not saying this right - anyone else?) DirkvdM 11:42, 25 November 2005 (UTC)

Homologous chromosome is the term you're looking for. Base pairs are seomthing else entirely. Chuck 01:00, 1 December 2005 (UTC)

Depends on which kind of trait. Some traits, require several genes working together, or hundreds, in fact. -- Natalinasmpf 14:05, 25 November 2005 (UTC)

    • I'm assuming you mean alleles, in which case the answer is no--172.155.50.13 22:44, 25 November 2005 (UTC)
  • On the other hand, if by "trait" you mean a characteristic such as eye color or hair color, the answer is still no. Many characteristics are determined by [1] environment, and [2] more than one gene, with [3] more than two allele variants for each gene. - Nunh-huh 05:10, 26 November 2005 (UTC)

[edit] Gemstones found naturally in Britain

Are there any gemfields in Great Brirain? If so, what gemstones can be found?

Whitby used to have a thriving jade(?) industry, but I suppose that doesn't quite count as gems. Shimgray | talk | 10:06, 25 November 2005 (UTC)
That's jet, not jade! There is still a small industry there. Physchim62 (talk) 10:51, 25 November 2005 (UTC)

[edit] Capacitor current question

How would I calculate the mean current flow when a capacitor is discharging? I have been given the time it takes for this to happen, and I've calculated capacitance previously, having been given the p.d., area of a plate and distance etc.

Do I need to use the equation of exponential delay of discharging a capacitor?

Also can you confirm that I am right in thinking that there is no change in p.d. where two plates are moved further apart while a battery is still connected, and capacitance decreases, so does charge on each plate and therefore energy?

---DK

For the first one, it would depend on how long the capacitor is discharging and how much resistance there is to the discharging. if the resistance is large and/or the time is small, you'd need the exponential formula. If you can assume that the capacitor discharged fully, then simply divide charge by time. As for the potntial difference, no, it does not change when the capacitor itself is altered. --Borbrav 00:03, 25 November 2005 (UTC)

[edit] Mechanics

Would you consider an AC vent mechanical? My friend and I had a long drawn argument in which I argued that a vent was mechanical, and he said that the AC unit itself was mechanical, but the vent was not. Since Webster defines mechanical as of or relating to machinery or tools, I don't see how he could be right.

Just my opinion, and I'm assuming AC is air conditioning. Since mechanical engineers design the vents, I'm happy to call the vent part of a mechanical system and therefore mechanical.--Commander Keane 07:30, 25 November 2005 (UTC)

[edit] Physical properties

Is water the only liquid that expands when frozen--````````

Arguably no. It is probably only the common one that does, although I think you could come up with another molecule with the intention of having it so. The reason is the fact that in the solid state the water molecules in order to be bonded into a "frozen, vibrating" kind of state, there's a lot of space between the molecules because well, the molecule is like a three-pronged star, and there's a lot of empty space between the molecules despite the fact that the molecules don't move a lot (the "prongs", that is the different component atoms are however due to their charge bonding each other in place)...a bit of a rough and messy description, so bear with me. Other materials don't have quite that structure so that might not happen because when the temperature drops and the molecules don't move as much, less space is wasted. Somebody more skilled should help you here, but I just was wondering if the three-component structure of carbon dioxide has anything to do with it's sublimation properties (ie. dry ice et al)....possibly you could also have a triangular protein... -- Natalinasmpf 23:37, 24 November 2005 (UTC)

Of course, there's bismuth "Density (near room temperature) 9.78 g/cm³; Liquid density at melting point 10.05 g/cm³". --Borbrav 23:57, 24 November 2005 (UTC)
There are lots of substances that expand when freezing—their constituent particles (atoms or molecules) form crystals that are less dense than the liquids from which they froze. Among the elements, there are five [62]: arsenic, bismuth, gallium, germanium, and silicon. (At room temperature, gallium is quite close to its melting point: 30°C or 86°F.)
I'm certain that there are classes of compounds for which the solid is less dense than the liquid state; I'm having trouble finding examples other than water, but that's probably largely because I'm finding it difficult to pull good density numbers for compounds off the web. I suspect that unsaturated fatty acids of moderate length would be good candidates—the kink at their double bond would tend to discourage efficient packing of the solid. (Check that in a good reference first; I'm just guessing.) TenOfAllTrades(talk) 00:34, 25 November 2005 (UTC)
This needs to be verified, but I recall a long long time ago when I was in grade school a science teacher remarked that there were three "common" substances for which the solid would float on top of the liquid: water, ammonia, and hydrogen sulfide. I wonder if this really is the case? Also plutonium has some extremely interesting physical properties and phase transitions...but that's a digression. --HappyCamper 02:39, 25 November 2005 (UTC)
I'm pretty sure that solid ammonia is more dense than liquid, actually. Can't speak for hydrogen sulfide, though. TenOfAllTrades(talk) 15:22, 25 November 2005 (UTC)
Not that I'd actually want to test hydrogen sulfide anyway. -- Natalinasmpf 15:30, 25 November 2005 (UTC)

[edit] Pumpkin: fruit or vegatable

Is the Pumpkin a fruit or vegatable?

  • See Pumpkin. Like the tomato, despite commonly being classified as a vegetable, the pumpkin is actually a fruit (it has seeds). --23:27, 24 November 2005 (UTC)
  • A vegetable is a layman's term...they overlap, and in fact, while scientifically there's no real distinction between "vegetables" (it is a cultural term, not a scientific one), a pumpkin is a fruit. It is not culturally treated as a vegetable either. Tomatoes can be considered both, I suppose. -- Natalinasmpf 23:30, 24 November 2005 (UTC)
    • Legally, a tomato is counted as a vegetable in the United States. See Nix vs. Hedden. - Ta bu shi da yu 07:48, 25 November 2005 (UTC)
      • LOL yes, but they aren't mutually exclusive - but the court case is hilarious though. -- Natalinasmpf 13:19, 25 November 2005 (UTC)

[edit] November 25

[edit] What is laboratory diagnostics?

Laboratory diagnostics are indeed great fun. --Borbrav 04:42, 25 November 2005 (UTC)

[edit] DC Current and Magnetism in Iron

A Wikipedia user has posted the following question to the Wikipedia help desk.

I know that DC current can produce an N and S poles on a piece of iron.Can you explain why ?

I would be grateful for any assistance you can give him.

Capitalistroadster 02:33, 25 November 2005 (UTC)

Every electric current produces a magnetic field around it. Ampère's law quantifies this effect, but doesn't explain it. It's a fundamental property of electromagnetism. —Keenan Pepper 02:48, 25 November 2005 (UTC)
I think maybe the question is also about induced magnetism. What's going on is this:
  1. The DC current produces a magnetic field.
  2. The electron spins in the material line up with this field.
  3. When the DC current is turned off, some of the spins remain aligned.
  4. These aligned spins are equivalent to many small currents, which produce their own magnetic field, making the iron a permanent magnet.
Hope that helps! -- SCZenz 07:46, 25 November 2005 (UTC)
The key term here is electromagnetism - electricity and magnetism come down to the same basic force, the electromagnetic force, which is one of the four fundamental forces (the other three being gravity and the strong and weak nuclear force). DirkvdM 11:48, 25 November 2005 (UTC)

[edit] Windows 2000 big problem

Greetings:

My dad is getting the following error message whenever he boots up Windows 2000 Professional:

disk I/O error: status = 00001000 windows 2000 could not start because the following file is missing or corrupt: please install a copy of the this file: <Windows 2000 root>\system32\ntoskrnl.exe

What can be done about this, other than a total re-format and re-install?

Thanks a lot!!!!!!!!!!

129.97.252.63 06:24, 25 November 2005 (UTC)

I found some general results - Google results. In situations like this, Google is always your best friend - search for the error in quotes ("<error>") and you're bound to find a plethora of forums, etc., with people who have already had a similar problem. You're probably best off if you go through some of those Google results yourself, because you're more familiar with your dad's system than I am, but one of the hits immediately caught my eye: Microsoft KB Q119467, which says the message you gave may be because "the Boot.ini file does not correctly reflect the correct %SystemRoot% folder for Windows". There's also a seemingly related workaround here [63]. Hope some of this helps - keep us posted on how things progress, or if you have more questions! --PeruvianLlama(spit) 07:21, 25 November 2005 (UTC)

[edit] economics

A profit maximising perfectly competitive firm can increase its profit by expanding output?

Maybe. According to the simple theory of supply and demand, it depends on how much they are producing currently and whether that is more or less than the equilibrium point. See your text book or class notes, and maybe supply and demand will help too. - Taxman Talk 22:07, 25 November 2005 (UTC)

[edit] LCD monitor query

In my LCD monitor, there is something called 'Gamma' in menu and it has three options namely -50, 0 and +50. Can I use any of the three options? I wish -50 because it is less bright. Will there be any Gamma rays coming out if I kept it in -50? Will I have gamma rays coming out anyway in all three -50, 0 & +50? Is there any reason regarding eye's health or something else which says we must keep it in '0'? Is -50 perfectly okay?

See Gamma correction; the adjustment of your monitor is unrelated to gamma rays. (LCD monitors–containing no cathode ray tube–are incapable of producing any ionizing radiation.) No harm will come to you or your monitor no matter which gamma setting you choose. TenOfAllTrades(talk) 18:16, 25 November 2005 (UTC)
... Except, possibly, from eye strain. An important part of avoiding eye strain is adjusting the monitor so it is comfortable to look at, so you should set whatever works for you. Notinasnaid 19:46, 25 November 2005 (UTC)
That's about Gamma correction, which determines where the stress is placed, on lighter or darker areas, which has an effect on (but is not the same as) contrast. And depending on what sort of visual you look at, a change in gamma will make it brighter or darker (try the same change in setting with a dark screen and a light screen). Unless you're working with photographs, choose the gamma setting that is easiest on the eye, as Notinasnaid suggested. DirkvdM 10:50, 26 November 2005 (UTC)
Any company that made home products which emitted gamma rays would soon lose all of its customers by attrition. No worries. --YixilTesiphon 05:35, 2 December 2005 (UTC)

[edit] physics.............................................

Physics. David Sneek 19:03, 25 November 2005 (UTC)

[edit] kirchhof's law

Kirchhoff's law of thermal radiation. David Sneek 19:03, 25 November 2005 (UTC)

Or perhaps Kirchhoff's circuit laws. --David Iberri (talk) 19:45, 25 November 2005 (UTC)

[edit] radio waves

Are radio waves dangerous?

No; otherwise radios would be illegal. Radio frequencies are at the lowest end of the electromagnetic spectrum; it's the high end ones that are dangerous (like Gamma rays and x-rays. smurrayinchester(User), (Talk) 21:44, 25 November 2005 (UTC)
Well, taken in moderation, they're harmless. But I wouldn't advise standing in front of a high power radar array or tv transmitter. Tzarius 21:54, 25 November 2005 (UTC)
"No; otherwise radios would be illegal." That is terrible logic. All dangerous activities are not illegal, and all illegal activities are not necessarily dangerous. Rangek 01:57, 30 November 2005 (UTC)
microwaves can, well, microwave you if you get hit by ones at the right frequency and high enough power. --Robert Merkel 14:15, 27 November 2005 (UTC)

[edit] gamma rays

Are gamma rays dangerous?

Yes. David Sneek 20:11, 25 November 2005 (UTC)
No, they're like candy, please try some first hand if you don't belibe me--Abon 1234 15:02, 26 November 2005 (UTC)

[edit] Lsass.exe???

Is this a bad thing?--172.155.50.13 22:41, 25 November 2005 (UTC)

It's a crital component of Windows XP, so it depend on whether or not you consider Windows to be a bad thing. —R. Koot 22:48, 25 November 2005 (UTC)
According to this site, lsass is usually a critical component required for login, but it can be a trojan/worm in disguise. The legitimate file is located in \Windows\System32 . The trojan is located anywhere else. Always double-check on Google before deleting random system files. Tronno 06:55, 26 November 2005 (UTC)
Lsass.exe is a component that was compromised by the Sasser worm. You might want to check around the web for worm removal tools, but here's one publicly available from Microsoft: [64]. Titoxd(?!?) 07:31, 26 November 2005 (UTC)
Do note that Lsass.exe should be running REGARDLESS of whether or not you're infected, so the above might not apply at all. --Pidgeot (t) (c) (e) 17:21, 26 November 2005 (UTC)
This page might help you with specific queries (but do some research -- lsass.exe is associated with the sasser worm, but the original version does Windows File and Print sharing or something). Agreed, it's pretty difficult to know what Windows XP is doing, but that's okay, it's from Microsoft and it's here to help. There's some more general information at this link about how to keep Windows usable (relatively speaking -- there are better products). Ojw 18:45, 26 November 2005 (UTC)

[edit] Woodworking joints

What kind of saw should one use to make fine Mortise and tenon joints? It would have to be delicate and adjustable

A coping saw? Depends on the wood. 59.167.3.93 02:53, 26 November 2005 (UTC)
Don't use saws, use a router. Hardware stores sell router bits for this purpose. linas 17:33, 28 November 2005 (UTC)

When constructing a mortise and tenon joint in wood by hand you would use a …..wait for it……tenon saw, to cut the tenon, and ….here’s the exciting bit…a mortise chisel to chop out the mortise. In the old days people didn’t mess about. Things were often called what they do. Hence the expression ...call a spade a spade.--Eye 20:57, 1 December 2005 (UTC)

[edit] 26 November

[edit] Qinetiq Approval

The following question was e-mailed to the help desk.

Qinetiq approval is given for equipment in the Marine Field e.g Automatic Identification System, Voyage Data recorder. Sometimes the approval Has Module A and sometimes Module D. I want to know the difference between these modules. What characteristics or specs. differentiate these modules. Pls help. Yr early reply will be appreciated.

Thank you for any help you can offer this gentleman.

Capitalistroadster 00:23, 26 November 2005 (UTC)

[edit] geographic centre of the world

Hi

Is there such a thing as the geographic centre of the world? If so where?

No. Superm401 | Talk 00:57, 26 November 2005 (UTC)
There's a spot in the Gulf of Guinea at 0° longitude and latitude, but there's nothing special about it. It's just like any other location on the equator. —Keenan Pepper 01:05, 26 November 2005 (UTC)
However, that coordinate system is arbitrarily defined, just like our mapping system (Europe in the center, "north" pole on top of the globe, etc.) Superm401 | Talk 01:34, 26 November 2005 (UTC)
Don't stand anywhere near that 0° lat, 0°long point during a nuclear war. All sorts of stuff happens there in simulations where someone's forgotten their radians to degrees conversion. ;-) Ojw 18:35, 26 November 2005 (UTC)

If you think 3-dimensionally, the world certainly has a geographical center: it's about 4,000 miles straight down from wherever you may be (assuming you're not reading Wikipedia from outer space). The Earth is a sphere, or more precisely an oblate spheroid, so it has a center. You just won't find it on a map of the Earth's surface.

Perhaps a more interesting idea is the geographical center of all land on the Earth's surface. I think the right way to compute this is to first take the average position in 3-dimensional space of all points of land on the Earth's surface (this will be a point deep inside the Earth, but not at the center), then use the point on the surface directly above this point. I happen to have at hand a suitable data set whose origin I was not told, and have been meaning to program this computation on it for ages... okay, done. If I got it right, the center is 44.50° north, 28.23° east, which is in eastern Romania near Constanta.

Generally, the center of the earth has not been regarded as a domain of geography, but rather geology. Superm401 | Talk 14:18, 30 November 2005 (UTC)

Another interpretation is given on this web page: the geographical center of the world's land area is defined there as (in effect) the point that minimizes the average great-circle distance of all land from it. The author of the web page computes this as 37.688° north, 35.438° east, which is in south-central Turkey. The web page states the position to be near Iskenderun, but actually it is closer to Adana.

--Anonymous, 09:15 UTC, November 26, 2005

Professor Anonymous has the facts at his finger tips! --Steve Summit (talk) 14:37, 26 November 2005 (UTC)

[edit] Seinfeld — Junior Mint in the patient

I just saw that episode of Seinfeld where Jerry and Kramer are watching an operation and a Junior Mint falls and lands inside the incision. Has something like that ever actually happened? What would happen to the patient in that circumstance? Would he get an infection from the non-sterile mint? —Keenan Pepper 01:00, 26 November 2005 (UTC)

Although there have been so many million operations in so many places and circumstances over the last 2 centuries, it is hard to say never, it is extremely unlikely. The trend has been to use smaller and smaller incisions over the last 2 decades, so that few operations involve large areas of open exposure. Overhead observation "bleachers" have not been used for decades in the US. I havent seen the episode but assume from your description that they were observing from an old fashioned elevated observation gallery rather than standing in the OR. No one observng in the OR gets anywhere near the incision because there simply isn't room between the surgeon, a resident, a scrub nurse, and usually more bodies than that. Theoretically the lodging of an unseen piece of candy would result in a foreign body reaction, probably with a local infection and abscess. The problem is that it would be hard to see the problem by x-ray. alteripse 03:08, 26 November 2005 (UTC)

Add to this the extreme unlikelihood of candy being in an operating room. --YixilTesiphon 05:37, 2 December 2005 (UTC)

[edit] daylight savings time

When did daylight savings time begin and end for San Francisco, California in 1954.

[edit] Formula

Daylight savings time has been between certain dates based on a certain weekend of the month for many years, and become a standard in USA which many computer systems anticipate. In its infinite wisdom, US gov now debating changing the formula, which will have ripple effects every place the old standard has been used. AlMac|[[User talk:AlMac|<sup>(talk)</sup>]] 05:01, 29 November 2005 (UTC)

[edit] History of Proportionality

I am doing a research paper for The history of math and I would like to include background on proportionality. I have search the web (and this site) and have had no luck finding a good article on the matter. --68.225.60.55 04:59, 26 November 2005 (UTC)

Remember that there are a number of different search engines out there that are best equipped for different kinds of interests.
  • Google is good when you already know something about a topic.
  • Teoma is better when you are new to the topic.
  • Vivisimo has clusters of sub-topics

AlMac|[[User talk:AlMac|<sup>(talk)</sup>]] 21:38, 29 November 2005 (UTC)

[edit] Closed captioning in Windows Media Centre

A user sent the following message to the Wikipedia help mailing list.

The Windows Media Center of my computer does a wonderful job on recording and stuff. The only thing that it apparently doesn't do is record the captioning. I recorded a show that tipically used to tape on VHS and when I Played back on my DVD player played fine except the captioning wasn't on on any of the shows. How can I get the recording to get the captionings???

Any help that you can give this user will be appreciated. Capitalistroadster 05:00, 26 November 2005 (UTC)

  • If you wanted to be a communist about it, you could always escape the great 'opression' of the evil microsoft corporation and switch to mac or linix--Abon 1234 15:00, 26 November 2005 (UTC)
I don't think Mac or Linux have Media Centre OSs. One thing that may work is activating the captions before recording, so that the DVD features them 'burnt in'. If you need the captions, and no-one else who might watch it would mind, this would be the best solution. smurrayinchester(User), (Talk) 19:14, 26 November 2005 (UTC)

[edit] Mt. Everest growth

How tall is Mt. Everest going to get? Elpenmaster 08:35, 26 November 2005 (UTC)

  • It doesn't grow, it's exactly the same height as it was 4000 years ago when it was first created--Abon 1234 14:59, 26 November 2005 (UTC)
Wasn't it created one day, 4004 BC or about 6000 years ago? Are you kidding? -- Toytoy 15:26, 26 November 2005 (UTC)
I assume that Abon is joking. Mount Everest is growing about 3 to 5 millimeters a year; it has grown a meter or so in my lifetime. I don't think anyone can predict, though, how tall it will ultimately get. — Knowledge Seeker দ 16:14, 26 November 2005 (UTC)
Remember that it is being eroded as well, so it may ultimately be worn away to nothing. The Laurentian mountains were once (I've heard) as high as the Himalayas, but they're little more than low hills today. —Charles P. (Mirv) 17:57, 26 November 2005 (UTC)
So Knowledge Seeker, you're 200 - 300 years old :-)? Seriously though, when Mount Everest stops growing will be determined by when the Indian plate stops colliding with the Eurasian plate, so the Himalayas will stop being lifted, and erosion will begin as stated above. smurrayinchester(User), (Talk) 18:00, 26 November 2005 (UTC)

Does anybody know how long those two plates will continue colliding into each other? Elpenmaster 06:59, 27 November 2005 (UTC)

No. We are almost sure that India will keep moving into Eurasia for at least 10,000,000 years, and presumably it will continue in that direction. According to the article on the Indian Plate, it is a very fast moving plate; just look at this picture. smurrayinchester(User), (Talk) 11:14, 27 November 2005 (UTC)

Mt Everest wasn't measured until fairly recent times so no one could tell if if it was bigger or smaller 4000 years ago compaired to today. Would anyone care to speculate on how high a mountain on earth could get before gravity begins to pull it back down again? I should think that there must be a limit to the hight of a mountian on earth?--Eye 21:07, 1 December 2005 (UTC)

Gravity doesn't do any work on things already on the ground, or part of the ground. --YixilTesiphon 05:39, 2 December 2005 (UTC)

"Olympus Mons ... is the tallest known mountain in our solar system ... The central edifice stands 27 kilometres (88,600 feet) high over its base". I've been told that's very close to the ultimate limit.

[edit] Rain gauges

What is to prevent water inside rain gauges from evaporating before measurement is possible? -Tim Rhymeless (Er...let's shimmy) 09:58, 26 November 2005 (UTC)

One reason would be that a funnel is used, so the rain is caught over a wider surface than the water surface, reducing (though not eliminating) evaporation. If that didn't suffice, I'd close it whenever it isn't raining. And when it's raining it won't be warm enough to cause much evaporation. Not that this answer is not based on any actual knowledge on my part, though. :) DirkvdM 11:47, 26 November 2005 (UTC)
But it seems to me that a funnel wouldn't be as accurate as one might like for measuring rainfall over a certain area. Trying to explain my question with an oversimplified example: If you were trying to measure the rainfall in a cylinder with a 7cm² base in order to find the rainfall for that specific area covered by the base, but had a funnel on top of it, measuring, say, 12cm² (rectally provided figures), wouldn't the area of the funnel cause the data to be skewed, since it would represent the rainfall data for a larger area? -Tim Rhymeless (Er...let's shimmy) 04:27, 27 November 2005 (UTC)
Yes, it would, but that is taken into account when inscribing the measurements on the side. Eg, doing it experimentally (as opposed to mathematically), for a gauge with a 12cm² rain entry point, we would add 12cm^3 of water to the funnel and mark "1" on the level at that point. Then we would add another 12cm^3 water, and mark it again, and so on. This way the shape of the gauge is irrelevant, it is only important that the volume stay the same and the gauge stays vertical. Tzarius 04:41, 27 November 2005 (UTC)

[edit] The flood?

How is it that people can explain away evidence of a flood a few thousand years ago? Neither evolution nor the big band even comes close to explaining a global flood? and if all the modern day animals were around back then when noah was around, then how could they possibly have evolved since then?--Lental soup 14:55, 26 November 2005 (UTC)

  • I'm an open minded person myself, and while I think the idea of noah is absurd, it's not like darwin or ID or any of the more 'progressive' theories actually make any more sense, just a new type of religion--Po po 14:57, 26 November 2005 (UTC)

There is much evidence for floods in the distant past (maybe even a few thousand years ago). See Deluge (prehistoric). However, there is no evidence apart from scripture or myths that a single worldwide flood occurred and acted as an evolutionary bottleneck, destroying all humans or animals except those on an ark. There is much evidence that large numbers of people and animals have been in various parts of the world for more than 6000 years. There is also some evidence that some organisms have changed during that time. Both of you are of course entitled to a belief that a flat world sits on a giant turtle, balanced by a Big Guy in BVDs, but don't expect the rest of us to think your opinions qualify as science. If you are just trying to start an argument, go to [[65]] and you will find plenty of takers. alteripse 15:32, 26 November 2005 (UTC)

If the flood occured exactly as documented in Genesis, a boat at most 165 metres long by 27 metres wide and 16.5 metres high could not contain 2 of every non-kosher animal (several million animals of various sizes), plus 14 of every kosher animal, enough food and safe water for them for 350+ days. However, the article on Noah's Ark has both sides of the argument covered in great detail. smurrayinchester(User), (Talk) 15:38, 26 November 2005 (UTC)
"...only a small portion of the animals were actually on the ark at any given time. The others swam, or in the case of non-buoyant animals like tortoises, they windsurfed until it was time for them to be rotated onto the boat." [66] David Sneek 15:58, 26 November 2005 (UTC)
Which big band do you think others are claiming is responsible for the biblical flood? Glen Miller's? Duke Ellington's? Tommy Dorsey's? Count Basie's? A lot of saliva does collect in the bottom of saxophones and trumpets, I agree, but it would have been a truly exceptional effort for a single big band to create a global flood in this manner. Or was this a collective effort? Enquiring minds want to know...or, alternatively, you can follow Alteripse's suggestion and take your argument elsewhere. The Reference Desk is not a debate forum. While I have my own personal opinions on the matter, as do many others here, we have no intention of arguing about them here. --Robert Merkel 14:13, 27 November 2005 (UTC)
On a (marginally) more serious note, when you are talking to people about this you should note that neither evolution nor the big bang are intended to say anything about a global flood. The big bang is about the origins of the universe, and evolution about the development of life. Asking why they don't explain a flood is like asking why the theory of gravity doesn't explain why we have five fingers. DJ Clayworth 16:36, 28 November 2005 (UTC)
You only have five fingers? David D. (Talk) 17:16, 28 November 2005 (UTC)

[edit] PDF management

I have thousands PDF documents downloaded from U.S. government websites. Some of them are text-based, the others are scanned images. How do I convert these files into text files so I can search them? -- Toytoy 15:33, 26 November 2005 (UTC)

If you open them individually in Acrobat Reader, you can "export to text" from the File menu (unless they are protected). Whether it's possible to automate this process to convert a large batch, I do not know. Shantavira 17:06, 26 November 2005 (UTC)
Aside: I know it's not what you are looking for, but you can search a .pdf (in Adobe Acrobat at least) by cliking on the binoculars, I think they call it "find". --Commander Keane 17:21, 26 November 2005 (UTC)
Aside: you can get Acrobat Reader to start much faster by deleting its plugins directory (no more 30 second wait to see a PDF) although that will break it's search feature (which is only within a single document anyway, and very slow). Ojw 18:28, 26 November 2005 (UTC)
You can get conversion tools; some are free, while alas many are proprietary. [67] There are also some links on Wikipedia at List of PDF software. If you know the URL of each source document, you may be able to use Google's built-in PDF-to-something-readable converter.
I've just checked, and my computer has programs called pdftotext, pdftosource, and pdftoppm built-in. Presumably these programs are available on most Linux PCs, and may be worth investigating.
Also, If your budget is large, you can always buy search-appliances from Google, which will handle PDFs. Ojw 18:17, 26 November 2005 (UTC)
Doesn't Google Desktop search inside the PDF documents too? --Threner 20:37, 26 November 2005 (UTC)
The image-based PDFs will have to be processed by OCR software, then individually checked - no OCR software is perfect, especially with non-standard page layouts and image noise. Tzarius 04:44, 27 November 2005 (UTC)

[edit] ARP

How does ARP work in WAN (Internet)?

It doesn't, it only works on LANs. You don't need the MAC address of the destination in order to send a packet to it across the Internet. ARP will be used locally on each of the LANs that the packet encounters as it traverses the WAN. -- Tim Starling 07:06, 27 November 2005 (UTC)

[edit] Microbiology

Can you tell me about the phage mu? what's its structure? Replication, mode of transmission, if genes are transfered using the phage mu, etc. Thanks! --23:50, 26 November 2005 (UTC)

Have you tried googling for mu phage? –Mysid 08:09, 29 November 2005 (UTC)

[edit] November 27

[edit] Alpha Player

Something called Alpha Player, which has a BMG logo on it, seems to have installed itself on my Windows 2000 Professional system and set itself up as the default media device for sound CDs without any deliberate intention or action on my part. Not only that: it doesn't show up in Change or Remove Programs, and it isn't listed in Set Program Access and Defaults.

Does anyone know anything about this, especially how I can get rid of the damned thing? Also, at the same time it appeared, the "stay on top" feature of my task bar stopped working (for the first time in the nearly five years I have had this computer. Coincidence? or something more sinister?

I believe this more or less coincided with my updating ZoneAlarm, but I would think it would be quite out of character for them to have done something like this. -- Jmabel | Talk 01:02, 27 November 2005 (UTC)

FWIW, stay on top will not work if a window defines its client area to fill the entire screen. This is normal regardless of whether or not the program uses DirectX to attempt to change resolutions.
As for the Alpha Player - I'm not sure, but based on what I can find, this might be related to Sony's rootkit. Have you played any CDs with XCP on your computer (list here)? --Pidgeot (t) (c) (e) 11:21, 27 November 2005 (UTC)
None of those, but I agree that other CDs might be carriers for other crap. -- Jmabel | Talk 04:22, 28 November 2005 (UTC)
Sounds like spyware. Run spybot and see what you find.--Fangz 17:08, 27 November 2005 (UTC)
Good thought. I ran Norton, but it didn't find anything. & Spybot doesn't find anything it objects to. I'd still be interested if anyone finds out anything about Alpha Player. I seem to have worked around it, but not truly gotten rid of it. -- Jmabel | Talk 04:22, 28 November 2005 (UTC)

[edit] Regarding AIDS disease

Can AIDS be cured? —Preceding unsigned comment added by 71.135.51.253 (talk • contribs)

I bet it says in AIDS. I seem to recall that it can be treated with drugs, and symptoms can be held off (possibly even indefinitely), but that there's no way to cure it yet. -- SCZenz 05:53, 27 November 2005 (UTC)
According to a number of quacks, sure. In the real world, currently available drugs suppress replication and reduce impairment of the immune system, but do not eradicate the virus from your body. alteripse 22:18, 27 November 2005 (UTC)
There was recent news of a man who spontaneously cured himself of HIV, but AIDS is another matter. Dysprosia 23:48, 29 November 2005 (UTC)

[edit] Regarding Bacteria at Poles of the earth

Can bacteria live at the poles (North & South poles) of the earth?—Preceding unsigned comment added by 71.135.51.253 (talk • contribs)

  • No, of course not, bacteria are allergic to ploar bears, dduh--172.157.22.219 05:49, 27 November 2005 (UTC)
    • But there are no Polar bears at the South Pole ;), are bacteria allergic to penguins too? David D. (Talk) 06:14, 27 November 2005 (UTC)
      • Yes--172.157.22.219 06:15, 27 November 2005 (UTC)
In all seriousness, I believe bacteria live pretty much everywhere on earth. - Akamad 06:19, 27 November 2005 (UTC)
Sorry for the tongue in cheek answer i couldn't resist. Bacteria are literally everywhere. They can survive the boiling hot springs in volcanic areas as well as well as live deep underground. David D. (Talk) 07:17, 27 November 2005 (UTC)
This is actually a real issue - if you remember the ALH84001 asteroid from Mars which landed at the South pole, alot was made of it as evidence for martian bacteria, but now the accepted explanation is that it was simply contaminated by terrestrial microbes. A good question is ask is if there is anywhere that microbes can't live.--Fangz 17:04, 27 November 2005 (UTC)
In the "is there anywhere that microbes can't live" department, I read an few articles a long time ago about terra-forming Mars with microbes. By seeding the poles with dark-colored microbes, they might darken the ice caps and absorb more light/heat. Then, they may melt and release more gas into the atmosphere. Eventually, Mars may have an atmosphere that allows for oxygen to collect in the air near the surface and then plants can grow. Back in the reality department, it would be easier, faster, and more effective to wrap Mars in a big plastic bubble and fill it with oxygen. --Kainaw (talk) 20:43, 27 November 2005 (UTC)
It is believed that Lake Vostok has microbial life. -- Миборовский U|T|C|E|Chugoku Banzai! 03:45, 28 November 2005 (UTC)
  • It depends on which bacteria you're talking about, but there are bacteria capable of resisting extreme heat or cold. The last kind would be perfectly happy on the North and South Pole. - Mgm|(talk) 10:06, 28 November 2005 (UTC)
As far as I know very little life can live below 0°C as all life discovered needs liquid water. Most of it can only survive to live and grow later. So bacteria can live on a polar bear, or pengiun, but not in an iceberg. MeltBanana 00:57, 2 December 2005 (UTC)
Biological antifreezes exist. One can consider a bacterium to be a solution o' stuff in water, and solutions freeze at a temperature lower than the solvent's freezing point by an equation relating to molality somehow which I can't remember at the moment.

[edit] Dye hair

I would like to ask if dyeing your hair would be of any damage to the brain?Would it lower ones intelligence?

Sure, dyeing one's hair blonde immediately reduces your IQ by at least 10 points until the bleaching fades...
Seriously, according to this page, there's no conclusive evidence of a health risk posed by the chemicals in hair dyes. Compared to your substantial risk of brain damage from a car accident, I wouldn't worry about it.--Robert Merkel 08:19, 27 November 2005 (UTC)
Most cosmetics and other such chemicals have been extensively safety tested. No company would ever dare risk the massive lawsuits that would result if any such harmful effects were discovered. So yes, so long as you follow the instructions, there's generally nothing to be afraid of.--Fangz 17:07, 27 November 2005 (UTC)
The main reason why chemicals used on your hair don't affect your brain is a piece of bone called the skull. --Oldak Quill 23:26, 27 November 2005 (UTC)
  • Extreme use of hair dye may damage someone's hair, but as Oldak said, your skull pretty much keeps it away from your brain. Note: Make sure the dye doesn't get into your eyes, or into open wounds. - Mgm|(talk) 10:08, 28 November 2005 (UTC)
    Or into the skull cracks!  Grue  17:51, 30 November 2005 (UTC)
I thought it was the blood-brain barrier. I'm sure the scalp picks up lots of chemicals, and passes them into the bloodstream.Joel 21:12, 3 December 2005 (UTC)

[edit] Microscope

My microscope has 100X, 450X and 750X. I am able to view things under 100X but when I adjust the lens to 450X or 750X, or I can see is the light and nothing else. What could be the problem here? Is it possible that 450X and 750X is too 'big' to see the objects?

Thanks for your time:-)

Are your focus and fine focus knobs working correctly? Try to adjust the light down. --Oldak Quill 23:23, 27 November 2005 (UTC)
If they're oil lenses, they need a drop of oil between the lens and the thing you are looking at. You need a sample that's not to thick, and you have to play with the light. High magnification is really hard to make work.linas 17:24, 28 November 2005 (UTC)

[edit] Cells

What is the minimum power of the microscope to view our cells, eg. the human cheek cell?

40x? Not very sure. -- Миборовский U|T|C|E|Chugoku Banzai! 03:41, 28 November 2005 (UTC)
  • The magnification of a microscope is determined by the magnification of the eyepiece (usually 10x) times the magnification of the objective. Usually I can begin to resolve neurons with a 10x objective (but not very well). Which means that the total magnification is 100x. However, I think cheek cells are pretty big, so youy should have no problem seeing them on a slide with a 10x objective. Nrets 02:56, 2 December 2005 (UTC)

[edit] Reprise Test

Does anyone know what a Reprise Test involves, It is somthing that relates to a test carried out on a Heavy goods vehicle

[edit] how temperature affects rubber

I am doing a project on how temperature affects rubber and I have found plenty of informatin on rubber but very little on how it is affected by temperature. I am hoping to find a diagram of polymers so that I can get an idea on what they look like or better yet how they are affected by heating or cooling them. Does anyone know about where I could find a diagram?

Our article Elastomer discusses the structure, but there isn't a picture.--Commander Keane 04:47, 28 November 2005 (UTC)

The affect of temperature on rubber was graphically demonstrated with the first space shuttle disaster. --Eye 21:14, 1 December 2005 (UTC)

Yes, look into the glass transition temperature article first. But over that critical temperature, warmer rubber is actually stiffer, since kinks and oscillations in the polymer chains tend to make them shorter. One interesting experiment you can try for yourself is to get a section of a popped balloon in your hands and stretch it rapidly, then touch it to your cheek: the order you've imposed by stretching it has forced entropy out of the structure, and it will be noticeably warmer. Let it cool while stretching it (should only be a few seconds, it's a thin membrane), then allow it to return to its original shape, and quickly touch it to your cheek again. It will feel cold: returning to a random arrangement required an input of energy, and the rubber absorbed heat in order to accomplish that task.--Joel 21:18, 3 December 2005 (UTC)

[edit] VB.net and access databases

Alright, I've been working on a program in vb.net for the last couple of months. My program involves ESSs and econmoic simluations and genetic algorithm-like things. Anyways, I'm a fairly novice coder (my code is ugly but it usualy works) but I can't figure out how to get my program to dump it's data into an acess databse every so often so i can then move it into excel for statistical analijsys (I wish I had better software, but this is what I've got). I've googled myself around town and have nothing (some sample code, but it's all above my head). I used to use VB6 (or was it VB4?) and I was able to acess Acess from that (it looks like they have changed everything). Can anyone give me a hand? Broken S 18:17, 27 November 2005 (UTC)

hurumph, I have the connection open now, but I can't figure out how to write to it. Broken S 19:04, 27 November 2005 (UTC)
If you are just trying to put it into Excel, why do it in such a round-about manner? Why not just export it as CSV or something like that? --Fastfission 23:24, 27 November 2005 (UTC)
can vb.net directly export to excel? I haven't found any evidence of that. Broken S 00:55, 28 November 2005 (UTC)
No, I don't think vb.net can directly write Excel files, but a CSV file is a simple text file which can be imported by Excel (or other spreadsheets) very easily. See our article on Comma-separated values.-gadfium 02:05, 28 November 2005 (UTC)
I guess I could do that. I'm not sure I would trust myself to get the formatting on it right...I just the access database working a minute ago. It was something small and stupid. Thanks anyways. Broken S 02:16, 28 November 2005 (UTC)
CSV is pretty easy. All you have to make sure you do is to use a common delimeter (separate fields with something like a comma or semicolon), and put any text strings into quotation marks (replace all quotation marks already in text strings with double quotation marks, i.e. " to ""). Excel can read that pretty easily. If you aren't by chance using text fields, then it's even easier, because the chance of mucking it up is much lower.--Fastfission 21:49, 28 November 2005 (UTC)

[edit] hormone

What is a hormone that is secreted as a result of stress?

See Stress (medicine)#Neurochemistry and physiology. —Keenan Pepper 22:00, 27 November 2005 (UTC)

[edit] neurons

What is a process by which neuron connections are refined and consolidated? --67.177.139.171 18:24, 27 November 2005 (UTC)

Doing your own homework. Thryduulf 01:52, 28 November 2005 (UTC)
It depends if you're doing your homework in some "soft" field, that is trying to make itself sound scientific by calling "learning" the process by which neuron connections are refined and consolidated, or an actually scientific pursuit such as neurology, where the answer would be closed to as-yet-unperformed original research than homework! - Nunh-huh 01:57, 28 November 2005 (UTC)
Looking up our neuron article might help. -- SCZenz 01:59, 28 November 2005 (UTC)

[edit] intelligence

A child's eventual intelligence is a result of two things. What are they? --67.177.139.171 18:31, 27 November 2005 (UTC)

  • Depends on who you talk to, but in most cases it is nature and nurture — genetics and environment. (The "depends on who you talk to" refers to the Nature-nurture debate, as different people will weigh those factors very differently). --Fastfission 18:39, 27 November 2005 (UTC)
No, it's genetics and homework! David Sneek 20:40, 27 November 2005 (UTC)
Well, it's certainly not just genetics and homework. Genetics and environment would be closer. Of course, the confounding question would be "how do you define intelligence?". - Nunh-huh 01:55, 28 November 2005 (UTC)
Then there's quantum mechanics and luck. Seriously. -- Natalinasmpf 01:57, 28 November 2005 (UTC)
Social and cultural surroundings. White people are fleeing parts of California because Asian kids study too hard, the school systems are too demanding, and the white kids can't compete. (It sounds insane, but it's been in the newspapers recently. This is a cultural artifact.). linas 17:19, 28 November 2005 (UTC)
There are different kinds of intelligence.
  • Book learning ... able to spout trivia to answer stupid quizes.
  • Math Whiz ... able to do heavy duty number crunching in brain, pretty fast, and come out with correct answers.
  • Able to visualize in multiple dimensions ... like those puzzles where pieces to fit together. Are you good at the game Tetris, aside from the dexterity issue at the keyboard / mouse?
  • Street Smarts ... able to survive in a hostile people environment.
  • Outdoor Awareness ... able to live off the land. The notion of how, in Science Fiction, we tell that a species is intelligent ... well they can build things like make fire, when relevant (Dolphin Intelligence measured a different way).
  • People can be good at one and lousy at others. So depending on which kind of intelligence we looking at, different things might contribute to being good in those areas.
  • Ability to learn things, to get ahead in material benefits.

AlMac|[[User talk:AlMac|<sup>(talk)</sup>]] 21:49, 29 November 2005 (UTC)

Junk food and television....you didn't say whether or not the required affect on intelligence was positive or negative.--Eye 21:19, 1 December 2005 (UTC)

[edit] Nuclear weapons effects

I've recently been playing around with a nuclear weapons effects calculator based on the one at the following URL: http://www.stardestroyer.net/Empire/Science/Nuke.html

If I put in yields of say, 15 kt or 1 Mt, it comes out just as one would expect in terms of the order of the width of the effects: 1. fireball is smallest, then 2. air blast/near total fatalities, then 3. ionizing radiation, then 4. air blast/structural damage, then lastly 5. thermal radiation has the widest reach. However for very small blasts, say, 1 kt / 0.001 Mt, the order is different: 1. fireball, 2. airblast/near total fatalities, 3. thermal radiation, 4. air blast/structural, 5. ionizing radiation.

That is, the ionizing radiation and the thermal radiation have changed positions. Is this an artifact of the calculations (made for larger rather than smaller explosions), or would this make sense from a physics point of view? --Fastfission 18:38, 27 November 2005 (UTC)

I've got no intution for something like this. If nobody else knows either, I'd ask the guys who wrote the program. -- SCZenz 23:40, 27 November 2005 (UTC)
Ionizing radiation might react with the atmosphere in such a way that it can never go very far from a blast. --JWSchmidt 23:57, 27 November 2005 (UTC)
Thermal radiation is given by the inverse-square law for distance (classical optics: lumens from a candle when you are disance R away.) Ionizing radiation is exponential law (each distance delta-R blocks some percentage of the total radiation). Not sure how damage from a shock wave/overpressure works, but once it goes subsonic, damage probably drops to nthing very fast. linas 17:15, 28 November 2005 (UTC)
Okay, that probably serves as a good-enough answer and sounds plausible. They are different physical forces and as such have different laws, so at some levels the could conceivably be in a different order. --Fastfission 21:29, 28 November 2005 (UTC)

[edit] Winding numbers and contour integrals

How can i show that the winding number defined in terms of curvature gives the same answer as when defined using a contour integral? How do i calculate the winding number of a particular contour by an explicit contour integration--129.234.4.10 19:59, 27 November 2005 (UTC)

Our articles on Winding number, Path integral, and Cauchy's integral formula should help. —Keenan Pepper 21:54, 27 November 2005 (UTC)

[edit] IT

What is a RAM Resident Program? Name 3 Utilities which are part of Windows XP. What is an Application Program? Please give answer by November 30.

Bwahaha, I really doubt that deadline is going to make anyone answer faster. DYOH. —Keenan Pepper 21:51, 27 November 2005 (UTC)
In case you don't know what that means, DYOH means Do Your Own Homework. --AySz88^-^ 22:34, 27 November 2005 (UTC)
Pretty strange we have an acronym for that here, since very few people probably ask for homework help twice. ;-) -- SCZenz 23:40, 27 November 2005 (UTC)
Your last question might be helped out by the Application program article, for the utilities I'd find an XP machine and look around. For the first, do a google search and try to figure out from context. -- SCZenz 23:40, 27 November 2005 (UTC)

[edit] November 28

[edit] is the number zero even or worth nothing?

It is an even number, and hardly worth nothing! It's worth been worth quite a lot in the development of civilization; see the 0 (number) article for some history. ;) -- SCZenz 00:54, 28 November 2005 (UTC)
IIRC, it is neither even nor odd. -- Natalinasmpf 02:19, 28 November 2005 (UTC)
Nope. It's divisible by two, and therefore an even number. (Check the link!) -- SCZenz 02:32, 28 November 2005 (UTC)
It is arguably odd, since it is equal to three multiplied by zero. -- Natalinasmpf 03:01, 28 November 2005 (UTC)
So I guess 6 is odd as well? -lethe talk 03:42, 28 November 2005 (UTC)
That's not how even and odd are defined. Please read even and odd numbers. -- SCZenz 03:06, 28 November 2005 (UTC)
I see your point; you're using the multiplication rules. I guess that, technically, that rule should have an exception. But being of the form 2n+1, for n an integer, is the given (and correct) definition of an odd number. -- SCZenz 03:07, 28 November 2005 (UTC)
That argument is flawed - it is true that odd*odd=odd, but then you're assuming that zero is odd in order to prove that zero is odd. (Similarly, even*odd=even doesn't prove zero is even, either.) However, zero is indeed even, since it is two times an integer (zero) [68]. --AySz88^-^ 03:11, 28 November 2005 (UTC)

Without a doubt, it's even. Perhaps you are confusing it with 1, which is neither prime nor composite. — Knowledge Seeker দ 04:15, 28 November 2005 (UTC)

Well my physics teacher did say it was neither odd nor even (in response to a question about the alternating day system in the school) - but that was a year ago and I'm not sure what the exact words were; I can't seem to agree with the concept that 0=0*2 being proof that 0 is even. -- Natalinasmpf 05:00, 28 November 2005 (UTC)

Your physics teacher must be mistaken then. 0=0*2 is not so much proof but a definition. The even numbers are ...,-6,-4,-2,0,2,4,6,... while the odd ones are ...,-5,-3,-1,1,3,5,... Starting with any integer and counting up or down by ones you will get alternating even and odd numbers. There is no reason to skip zero. I understand your confusion but it's really not a controversial subject. Two times any integer is an even number. Any even number minus two is another even number. Any odd number minus two is an odd number. An exception for zero would have to be explicitly written in; zero would have to be explicitly defined as neither odd nor even, since by all other rules and properties it should be an even number. And there's really no reason to do that. — Knowledge Seeker দ 05:21, 28 November 2005 (UTC)
0=0*2 isn't useful proof, but 0=0/2 is. Any number which gives an integer when divided by 2 is even. - Mgm|(talk) 10:13, 28 November 2005 (UTC)

[edit] what is optic engineering

—Preceding unsigned comment added by 65.15.99.55 (talk • contribs)

a little more context might be useful, also just putting it into google gets some useful links. one of them gives this: Description Optical Engineering is the study and practice of using, detecting, transmitting, and manipulating light to engineer products and systems. Optical engineering impacts modern devices and systems involved in communication, display, data storage, illumination and remote sensing. * Basic optical principles, including geometrical optics, optical aberration, diffraction theory, optical interference, and crystal optics. * Light source, detectors, radiometry, photometry and colorimetry. * Trends/state-of-the-art in optical technologies/devices, including holography storage, fiber communication, optical testing and optical display Boneyard 10:43, 28 November 2005 (UTC)

[edit] Electrode potential diagram

Does anyone know of a specific name for the type of diagram shown on the right, where electrode potential is plotted as a function of pH? The diagram is plotted for chlorine, and shows the disproportionation of chlorine in solution to chloride and hypochlorite above pH 2. Physchim62 (talk) 06:01, 28 November 2005 (UTC)

  • Physical chemistry was a long time ago for me, but I seem to recall them being called Phase-transfer diagrams, but please don't take my word for it. - Mgm|(talk) 10:15, 28 November 2005 (UTC)
I believe those diagrams are the celebrated Pourbaix diagrams. --HappyCamper 00:25, 29 November 2005 (UTC)

[edit] Preparation of oxygen

We can prepare carbon dioxide gas by adding magnesium to an acid. What I want to know is how do we prepare oxygen gas?

If you have hydrogen peroxide handy, it readily decomposes into water and oxygen, especially if you add a catalyst like manganese dioxide or potassium permanganate. —Keenan Pepper 15:59, 28 November 2005 (UTC)
Oh and by the way, magnesium and an acid will produce hydrogen, not carbon dioxide. —Keenan Pepper 15:59, 28 November 2005 (UTC)
Keenan Pepper is right, and the easiest way to get O2 at home is to use electrolysis.--YixilTesiphon 05:50, 2 December 2005 (UTC)

[edit] Petri dish

Why is the petri dish used in the bacteria culture? What are the other usage of a petri dish?

have you check the Petri dish article? Boneyard 10:47, 28 November 2005 (UTC)

[edit] Vitamin D

How does vitamin D help/aid in the absorption of calcium?

have you checked the Vitamin D article? also remember you can sign your questions by 4 tildes ~~~~ Boneyard 10:50, 28 November 2005 (UTC)

[edit] Liquid Nitrogen

What is the temperature of liquid nitrogen when it is used to treat viral warts? Why is it that the Liquid Nitrogen Treatment for viral warts is better than other kinds of treatment?

i think the idea must be clear to you now, check the articles about these subjects first. they contain the answers you are looking for. Boneyard 10:52, 28 November 2005 (UTC)

Liquid nitrogen freezes and destroys tissue it contacts. It is no different than burning with cautery, burning with acid, or abrading away. By all methods, it is important to avoid damaging normal tissue surrounding the wart. Unfortunately many skin warts are able to survive and recur. alteripse 13:31, 28 November 2005 (UTC)

[edit] Bacteria

Enzymes are inactivated at low temperatures. So does low temperature deactivates or kills bacteria?

Extreme cold kills some bacteria, but many can survive freezing. alteripse 13:29, 28 November 2005 (UTC)

[edit] Dense sets

Both the rationals and the irrationals are dense in the reals, yesno? I can easily prove that there is an irrational between any two rationals: Assume a and b are rationals and a<b. Then a+\frac{b-a}{\sqrt{2}} is an irrational between them. But how do I go about proving there is a rational between any two irrationals? — JIP | Talk 13:56, 28 November 2005 (UTC)

You just have to get your rationals close enough together. For example, suppose k is a rational that is less than b-a. Think about multiples of k. Show that there must be at least one multiple of k between a and b. Gandalf61 16:13, 28 November 2005 (UTC)
Do you mean that in this case, a and b are irrationals? Let k be a rational that is less than b-a. Let n be the highest possible integer so that nk<a. (Because the values of both a and k are fixed, we can always find such a unique n.) Now (n+1)k>a because of our choice of n. Also, because nk<a<(n+1)k, then (n+1)k-a<k<b-a, and thus (n+1)k<k-a<b, which means (n+1)k<b. Thus a<(n+1)k<b and we have found a rational between a and b. This all of course assumes that for any irrational, we can find a smaller rational. One way to do this is invert the irrational, find the next greater integer, and invert that. Does this work? — JIP | Talk 18:49, 28 November 2005 (UTC)
I just thought of an easier way. If x is a real number, we define xi to mean the i:th digit after the decimal point in x's decimal representation. Assume a and b are irrationals and a!=b.. Thus they both have an infinite number of digits after the decimal point, and they do not have a finite-length sequence of digits that repeat over and over. Because a!=b, and the reals are well ordered, there is a unique i so that \forall j \in (0, ..., i-1): a_j = b_j and a_i \neq b_i. Now define a new number c so that \forall j \in (0, ..., i-1): c_j = a_j and have ci be between ai and bi (if bi = ai + 1 then let ci = ai and ci + 1 = 5). Then let all the remaining digits of c be 0. Thus c is strictly between a and b, and because its decimal representation ends in a never-ending string of 0's, it is rational. — JIP | Talk 20:20, 28 November 2005 (UTC)
Speaking from four years of experience at mathematical olympiads, I can tell you that the first proof would be regarded as 'better' or 'more mathematical', though the second one was the easiest one I could think of, as well. ;) ナイトスタリオン ✉ 20:42, 28 November 2005 (UTC)
I came up with JIP's solution too, but I couldn't express it in a way that didn't seem like handwaving. Thanks, JIP! --jpgordon∇∆∇∆ 03:48, 29 November 2005 (UTC)

[edit] Interpreting U.S. Forest Service 'bearing tree' markers.

How can a person interpret the U.S. Forest Service 'bearing tree' markers to determine the location?

The United States Forest Service places survey markers on trees within the national forests. These are yellow metal plates about 5 inches by 4 inches in size and have numbering on them related to the geographic township and section where the marker is located. The markers appear to have a reference to a section corner with distance and direction, but I haven't quite figured out how to decode the system.

You'd probably need a good map, perhaps a USGS topo map. The "township and range" system, with its serpentine-numbered sections, is somewhat arbitrary, and is based on local surveys specific to the part of the country you're in. There's no algorithmic way to convert, say, between township/range numbers and latitude/longitude. --Steve Summit (talk) 22:07, 28 November 2005 (UTC)

[edit] Why Did Sodium Carbonate (Washing Soda) Dissolve an Oil Stain

Thank you for your prompt answer concerning Sodium Carbonate as a stain remover ( "Arm and Hammer's Washing Soda" was used to remove an oil stain without detergent, just soaked in hot water and Arm and Hammer).

The answer mentioned that ..."It softens water by binding to dissolved calcium and magnesium—in hard water detergent molecules tend to bind to those dissolved metals instead of to oil and dirt. Sodium carbonate is also a weak base; in some cases this can increase the solubility of stains in the wash water, removing them from clothing..."

If the water was "soft," and the water did not have to be be softened by binding to as many dissolved calcium and magnesium molecules, would the base of sodium carbonate be able to attack the stain by increasing the solubility of the stain since it was not softening the water as much.

Thanks again. --Curious Person

[edit] Changes to Earth's crust

I'm helping my 5th grader with a report. He needs 3 causes of changes to the earth's crust. I have found continental drift. It appears the other 2 are magnetic force and rotation but i am not certain. Where would i find this info? 67.21.184.145 18:53, 28 November 2005 (UTC) 5th grade Mom

If he's been asked to find three causes, the examiner is probably looking for three causes described in the course textbook. Try looking there. Mark1 19:23, 28 November 2005 (UTC)
Can these be any 3 changes, or can they be specific? Magnetic force is actually generated by rotation I do think (ie. a dynamo effect) and does little to change the crust, besides the fact of protecting it from solar wind...ie. it doesn't actually affect the mantle that much (if I remember correctly). I'm not sure if other forces like weathering are included. Continental drift might actually be a collection of other "causes" defined by this homework, and I honestly don't know what the syllabus is like, so I'm not sure if things like fault formation et al would count or not. -- Natalinasmpf 00:57, 29 November 2005 (UTC)

[edit] Earth Science Resources

I do not know answer to Earth Crust question for sure ... I can guess about Volcano, and Super volcanoe, giant rocks striking the planet like the one that wiped out the dinosaurs. But there may be useful hints at places like:


AlMac|[[User talk:AlMac|<sup>(talk)</sup>]] 21:54, 29 November 2005 (UTC)

[edit] First aid technique question

What is the technique of checking for brain trauma through eye movement correctly properly called?

Circeus 19:36, 28 November 2005 (UTC)

Checking cranial nerves. alteripse 03:47, 29 November 2005 (UTC)

[edit] Winmodems

Greetings:

Does anyone here know about the status of winmodems support in Linux?

Regards,

129.97.252.63 19:44, 28 November 2005 (UTC)

Yes, they call them Linmodems. --Heron 20:12, 28 November 2005 (UTC)

[edit] November 29

[edit] DVD player firmware upgrades and XviD

Is it possible to upgrade a DVD player's firmware so it can play DivX and XviD encoded AVI files? I'm not sure whether it's a hardware or software thing. Is using the firmware from a different brand of DVD player relatively safe? There wouldn't really be major differences, would there? I own an LG V692W, or LG V692WK, and need to play XviD .avi files. —Preceding unsigned comment added by 202.7.176.134 (talk • contribs)

In general, no. XviD uses MPEG-4 encoding, a significantly different compression scheme, to achieve much better video compression at the same perceived quality levels as is achieved by the MPEG-2 scheme used for encoding DVDs. Most DVD players do their video decompression in hardware with a dedicated chip, and it would be very unlikely that that chip would also have the ability to decode MPEG-4. You will probably have to purchase a new DVD player for the purpose; the good news is that DVD players are so much cheaper than they used to be these days. --Robert Merkel 02:27, 29 November 2005 (UTC)

[edit] Audio File conversion (Ogg Vorbis to MPEG-4)

I have some audio files in .ogg file format that I want to listen on my Apple iPod. The iPod does not have the right codec for these files and can only play files in .wav, .acc, .mp3, and .m4a formats. Some of the free audio format converters (encoders) that I obtained from the Internet could not convert the files correctly, the encoded file was completely silent (4 minutes of no sound). Are there better encoders out there? Am I doing something wrong with the software? And is there an Ogg Vorbis codec for the iPod that I am unaware of? — Kjammer ⌂ 00:47, 29 November 2005 (UTC)

See wikipedia:Media. Audacity w/ LAME would solve your problem. Raul654 00:48, 29 November 2005 (UTC)
Officially, the iPod's firmware is completely closed; there are no codecs available other than the supplied ones. Unofficially, the iPodLinux guys apparently have a working Vorbis implementation running on some of the newer iPods.
If you don't feel like messing with your iPod's guts, another option that's worked well for me in the past is to use a plugin (found here) that enables QuickTime to read Ogg files. You can then open the file in iTunes just like any other, right-click on it and select "Convert to AAC". —David Wahler (talk) 03:24, 29 November 2005 (UTC)

[edit] Asperger's and ADHD

Is there any debate within the psychiatric/psychological community over whether asperger's and/or ADHD actually exist? Where could I read further on this? (I have googled)

Both Asperger syndrome and ADHD refer to objectively describable patterns of behavior. In that sense there is no debate as to whether these patterns "exist". You need to re-think your question. However, there have been disagreements over:
  1. whether these patterns of behavior can be clearly distinguished from extremes of the normal distributions of personality patterns and behaviors present in the human population;
  2. whether there are situations where applying a formal diagnostic label to a pattern of behavior may have some negative effects;
  3. whether to call such patterns "diseases" if the persons affected seem to feel no distress over the behaviors and their consequences;
  4. whether to apply the word disease to a pattern of behavior that may not be as detrimental in some environments than others;
  5. and so on. Some of the debates are over the boundaries of the term disease; some over power relationships, like who gets to label something abnormal; and many others.

Google again. Try "biology of Asperger syndrome" and "biology of ADHD". I promise lots of relevant hits. Let us know what you decide. alteripse 03:38, 29 November 2005 (UTC)

[edit] Diabetes

I was reading the article about diabetes and one question came up. I`d know why non-diabetics can not use `artificial` insulin to the day-to-day living.So, doing that they would use less of their own, `natural` insulin and their bodies would not be overcharged by a big amount of glucose that they ingest. So , non-diabetics could prevent the disease . For example , a non-diabetic person that eats to much carbs (glucose) per day is increasing their risk to get the disease , because they overloaded their organism with a big amount of sugar that their body cannot handle 100%. But , if that same person ingest the same amount of sugar and use an `artificial` insulin for that , their body would not have to use their insulin , not overloading the body , and for consequence , not causing diabetes .

Thanks for your answer. --69.209.115.22 02:49, 29 November 2005 (UTC) Michigan reader --69.209.115.22 02:49, 29 November 2005 (UTC)

Interesting question and not as crazy as it might seem at first look to some. For the purposes of this answer let's restrict it to type 2 and let's use the common simplified story that the following sequence of stages happen as someone slowly develops type 2.

  1. Person has a vulnerable pancreas. This is presumably a genetic trait or at least one present for many years if not decades before problems occur and there are probably more than one gene for this type of vulnerability. The vulnerability means that if the pancreas is "stressed" or "overworked" or "insulted" by excessive exposure to hyperglycemia, that the cells may die in some conditions.
  2. Person slowly develops a diminished sensitivity to insulin, requiring increased insulin production by the pancreas over months or years or decades. Sugars are still normal at this stage of things but insulin production is high. The most common causes of reduced sensitivity are obesity and low physical activity. If an overweight sedentary person does not have the vulnerability factor, this can continue for many decades.
  3. If person does have the vulnerability trait the pancreas eventually begins to be unable to keep up with the insulin demand. At this point the sugars may still be normal most of the time, especially fasting, but they may go a little higher or take a little longer to return to normal after a high-carb meal. This is a state of "prediabetes" and there is evidence that most people who reach this state will go on to develop diabetes.
  4. Diabetes can finally be diagnosed when fasting glucoses are recurrently above 125 or random daytime sugars exceed 200 mg/dl. As the glucose levels stay high the damage to the beta cells becomes irreversible and they begin to die.

Now the above is perhaps oversimplified and we do not understand all the details of all the steps and there may be other routes to type 2 diabetes.

However, let's get back to your question. We have fairly strong evidence that doing something at stage 3 to reduce hyperglycemia or pancreatic damage may prevent the irreversible death of the beta cells. At stage 3 the person does not technically have diabetes, but can be said to be "prediabetic". This is when exogenous insulin injections might spare the person's beta cells from exhaustion and hyperglycemic damage. So what would be down side to your idea?

  1. We don't know how to tell who is vulnerable. Family history helps. It isn't just obesity and high insulin levels, because many fat people with high insulin levels never develop diabetes. They probably wouldn't want to take insulin because their pancreases are not at risk.
  2. Taking extra insulin in that circumstance may make it a bit harder to lose weight, which is what the prediabetic person desperately needs to do.
  3. Needles. Hypoglycemia risk. But you knew that.

So the answer to your question is: I can imagine a situation where that might be a prudent thing to do. Is that what you had in mind? alteripse 03:26, 29 November 2005 (UTC)

[edit] Fat

Recently, I realised that most or all of the fat people eat at very fast speed. Does eating fast make you fat or it's just that fat people eat fast?

This has actually been researched. The relationship is too small to be causal. alteripse 03:45, 29 November 2005 (UTC)

Actually, what happens is that the pituitary gland releases a hormone that tells the stomach it isn't hungry anymore. "Slow" people give that hormone (I can't recall the name right now) more time to reach the stomach, so they actually end up eating less. Titoxd(?!?) 03:58, 29 November 2005 (UTC)
Actually, there is little evidence for either of those assertions. First, there are no pituitary hormones that serve as signals to the stomach that it is full. Gut, fat, and hypothalamic hormones (but not pituitary) signal the brain, not the stomach, about incoming food, about fuel levels in the liver and blood, and about amount of body fat. Second, speed of eating has been found in empirical studies to have only a weak relationship to obesity, despite the neat hypothesis that fast eaters get fat because they don't get the "full" signal before they have eaten too much. As someone famous said, "many a beautiful theory has foundered on the shoals of evidence", (or something like that). alteripse 04:29, 29 November 2005 (UTC)
I think they eat fast because of the hormone levels - rather than the other way around. -- Natalinasmpf 22:03, 29 November 2005 (UTC)
While I am not convinced that it has been established that most fat people eat faster than most non-fast people. alteripse 23:44, 29 November 2005 (UTC)

[edit] Installing XP on FAT32

Greetings:

Is it possible to install Windows XP on FAT32 partitions? Today I tried to install Windows XP on a 40GB FAT32 partition but XP install refuses to proceed until I have formatted that 40GB partition as NTFS.

Regards,

129.97.252.63 04:16, 29 November 2005 (UTC)

It appears that while Windows XP supports booting off of FAT32 partitions of any size, the FAT32 formatting utility is limited to a maximum of 32GB. If you're really sure that you don't want to use NTFS, there are a couple of workarounds. One simple one is splitting the partition in two to get around the size limit (don't do this if the partition has data you want to keep!). You might also want to try the instructions here, which use a Windows 98 boot disk to do the formatting. Hope this helps. —David Wahler (talk) 04:33, 29 November 2005 (UTC)

You can partition ur drive without having to format it. there are a variety of softwares available (eg. powerquest partition magic) which let you change things around your hard disk without losing any data present. this software is also useful if you want to change the size of the partitions you have already made. --203.92.55.216 13:12, 29 November 2005 (UTC)

[edit] Computer arcana for the web.tv user

Hi, I own a MSN(nee WEB)TV. It has a browser and email and it is fine for home, but, I have little knowledge of deep computer running details. At work, late at night, I have used the company computer to go to Google and Yahoo and on occasion gone to -Adult- sites. I know how to "clear Google history". I know how to use "tools" to delete "recent history". But.. tonight I discovered "internet options" in "control panel" in "my computer" on the desktop and saw a _lot_ of 'incriminating' temporary internet files. Some were very easy to identify and others were either Spyware I attracted (edge.ru4.com, ad.doubleclick.net, etc) or anti-adware that I should leave alone.

I went to Google with some terms and addresses which sent me to computer (self named) Geek forums which listed the few I have cited here. A few were a bit hard to follow as there were lists of "antispyware programs" that looked a tad like the FORTRAN they tried to teach me in 1969. 8-)

Finally, the point and question: is "Akamai.net" one of the 'good guys'? How about "a.as-usfalkag.net"? I was able to help myself by hi-lighting something and clicking on "properties" and anything with a "last [adjusted] date" that was a year or more old was something to keep and anything with today's date and no other info was 'bad'. Some of the 'bad' had today's or tomorrow's date to 'expire' and some had 'none' as a date.

Is my only opton to go through each and every one that happened on my shift and check 'properties'? Google and Yahoo in general aren't bad, but, they may have a link to my 'indiscrection' and should not be kept. Some 'cookies' to Yahoo may be needed and some files are jus on how to make the page look right (I think!)

Can anyone [here] help me cut this Gordian Knot? Thank you for your time and {web} space. Sign me: Frustrated and a bit scared. bye,

Why not just delete all of the temporary internet files and cookies? Is there any reason to keep any of them? Temporary internet files themselves are just cached copies of the files you downloaded as parts of a website, so revisiting the same website soon after will be that much quicker, because you no longer need to download those files you have cached. Deleting all the temporary internet files shouldn't pose any serious problems to a normal system - at worst, your websites will load a little bit slower than normal for a day or so. If you decide you want to delete everything, you can open up the 'Internet Options' again. Under the 'General' tab, there's a section for 'Temporary Internet files' and you can simply click the 'Delete Cookies...' and 'Delete Files...' buttons in order to delete them all. This might also free up some disk space (you could be helping your employers out after all). Right underneath, in the 'History' section, you can clear out the history. Forgive me if I'm repeating things you already know. For future reference however, you should note that if your employers really want to know what you're accessing at night, it's almost certainly possible for them to find out, whether it be from logs on the computer itself, or network access logs that are stored who-knows-where. In the future, maybe you should bring your adult entertainment with you from home, on a CD/USB-key, or in a magazine. Better yet, why not just wait until the shift is over? It can't be worth losing a job over! Cheers. --PeruvianLlama(spit) 09:27, 29 November 2005 (UTC)
Companies can, and some companies do, sack people for visiting "inappropriate" sites. Do you think that they do this by coming around and checking each computer's browser history and temporary internet files? Well, maybe, but more likely they simply have a log of all the sites visited by every work computer. There is no escaping this, you can only hope they choose either don't have this policy, or won't check the logs from this day. Check your company rulebook and your contract of employment to see what is likely. Notinasnaid 16:37, 29 November 2005 (UTC)
At my first job, my boss actually saw me go to an adult entertainment site while I was working on program code. He said me "close that rubbish", so I did, and then I proceeded to demonstrate the code to him exactly as I had originally intended. — JIP | Talk 19:19, 29 November 2005 (UTC)
If you connect any computer appliance without protection, like anti-virus, anti-spyware, firewall, UPS, etc. then you might not have your contents for very long, because this is like having an apartment in a high crime neighborhood, in which there is no door or windows, the place is wide open to criminals to walk in and help themselves, deface the place, set fire to it, all kinds of mischef.
I suggest you visit the magazine section of a major book store, sample the various Personal Computing Magazines for Dummies (I think Smart Computing is the best, but everyone has their favorites), then either subscribe to whichever floats your boat, or visit the same retailer regularly.
I believe everyone needs a spectrum of protections against computer insecurity and for the beginner, that a suite of protection from a major outfit like Symantec is best, assuming they have a suite that will run on Web TV.
Otherwise you have to figure out what all the different protections are that you need, and shop around to get what you need in each of many areas, comprehend which products are in conflict with each other, which are frauds (claim certain protection but are really some kind of malware}.
You might have a chat with the computer manager where you work. Indicate that you have concerns about bad stuff when we connect to the internet, that you not know all the different kinds of spyware, adware, viruses etc. that can infect a computer thanks to visiting the Internet or getting e-mail. You desire guidance regarding your responsibilities to tty to protect the company computer that you use from that kind of stuff.
Is there some company policy about individual employees installing what they think is anti-spyware, or can you do that for us? Is there a particular one that you reccommend?
Are we employees supposed to do some regular computer cleanup like disk space compresses, and deleting old records, or do you take care of that for us?
Are there prohibitions we ought to be aware of?

AlMac|[[User talk:AlMac|<sup>(talk)</sup>]] 22:16, 29 November 2005 (UTC)

Hi, Thank you all for the info. I would 'view' at work and 'go to' at home. (WEBTV is a big computer in California and I an in (another state) with a browser and email dialed-up and converted to show on a TV screen.)Are you saying that if I deleted all temp internet files, reaching a site might be a tad slower but still act normal? Some seem to be gifs and jpegs for the (company's) main page and link to my email, etc. and some have specific expiration dates in the future. Possibly the latter are anti-spyware, etc that some one took time to save in this "temp" folder.

Am I safest (for the correct running of programs, not just getting caught) going thru and deleting one at a time anything that has no real 'Properties'. Were the two files mentioned in the original (Akamai.net and a.as-usfalkag.net) 'good guys', ie: anti-'bad guy' stuff? My looking on the net was a bit confusing for those two. I want to make it easy for the computer to do what it must and not remove anything someone actively looked for to have as a anti-bad guy tool.

If I am looking at a desk top that needed no password to access, is the "My Computer" for that station only or for many? Is the one station that needs my pasword unaffected by these files? My MSN (WEB)TV takes up enough of my time and becoming more computer literate beyond the scope of what I need to know at work, where they will train me in 'how to' and not 'how it did that' is not a high priority. My first job was with a TV station with BIG tubes and copper waveguides. Today it is all in a drawer's woth of space (not counting the gov'ts mandate that we convert to digital by (1909?). I am 'old school'. 8-) Thanks, again for time and space [here], bye198.252.13.100 01:36, 30 November 2005 (UTC) (merged from below)

There should be no problem at all with deleting everything in the Temporary Internet Files folder. They are completely non-essential, and are used only to slightly speed up accessing of sites you have already visited once before. None of them are needed.
The items in that folder are not any sort of spyware, nor are they anti-spyware. They are simply copies of files you have viewed from web sites in the past. Just to use an example: a.as-us.falkag.net is one of the servers of Falk eSolutions AG, one of the Internet's major advertising companies.
As for your last question: assuming the computer is not part of a network (in technical terms, as long as it is not a member of a domain) then anything under "My Computer" is only relevant to that computer. Beyond that, I really can't say anything else; the details depend on the specifics of your network. —David Wahler (talk) 03:32, 30 November 2005 (UTC)
It might be useful to you to post separate questions here about separate threads.
  • Computer Housekeeping for the Beginner ... what kinds of cleanup is advisable to keep a Personal Computer running smoothly, such as killing TEMP files, running DEFRAG, occasionally rebooting, backing up, having a UPS, paying lipservice to computer security, deleting cookies ... there's a long list of things ... and secondary to that is relative importance of each other ... the issue is what do we need to do on a regular basis to avoid getting into trouble because we not doing that stuff.
    • Computer Protection for specific applicaitons ... what we need to do varies with the application.
      • In the e-mail comes all kinds of scams telling us that this or that file is a bad spyware virus whatever that we need to delete ... we go delete it, and now our Windose is broke ... it was a program essential to the running of Windose ... we just fell for an evil scam.
  • Then there are questions of continuing education about how best to cope with the individual threats, and topics that are not 100% good or bad.
    • We get cookies when we visit some site, to tell that site who we are and what we interested in ... sometimes cookies needed to help us log onto that site and stay logged on in future visits, so we might not want to delete all cookies, to avoid hassle revisiting favorite web sites.

AlMac|[[User talk:AlMac|<sup>(talk)</sup>]] 06:29, 30 November 2005 (UTC)

[edit] kidney failure treatment by hemodialysis

Please i will like to find out who developed the following water treatment methods: Reverse Osmosis, Softeners, Ion-exchange resins,U-V irradiation, Ultra-filtration. When were they first used for hemodialysis water treatment with references if possible. Thank you.--82.128.3.59 08:53, 29 November 2005 (UTC)

Have you read our Dialysis article? Thryduulf 12:31, 29 November 2005 (UTC)
It doesn't answer his questions. He is going to need to do some serious library work. He needs a review article on history of hemodialysis (like PMID 3517604). A google search on "history of hemodialysis" does yield a lot of hits, some of which look like they might have some of the answers: [69]. alteripse 12:53, 29 November 2005 (UTC)

[edit] Discovery of wheel

I would like information on the discovery of the Wheel. Which invention is associated with it?

  • Check out our article on the wheel. It lists its history and also some related inventions like cars, spinning wheels, cog wheels, fly wheels, etc. - 131.211.210.16 11:14, 29 November 2005 (UTC)

[edit] Compress a Nucleus ???

what will happen if we compress a small quantity of a material so that interspacing between molecules becomes in the order of atomic distances? What will Happen if an atom is placed in very intense electric field? What will happen to protons and electrons when they will come too close to each other? And wht will happen to those neutrons? Will neucleous explode?? Can zero point energy be used? Plzz mail me if u find any info regarding this at [email address removed]

One example of highly-compressed matter is a neutron star. In particular, note that under sufficient compression (due to gravity), electrons and protons combine via the weak interaction to produce a neutron (and a neutrino, which flies off and is never seen again). Super-compressed nuclear material of a different sort is produced at the Relativistic Heavy Ion Collider, possibly including Quark-gluon plasma. That's a start, at least. -- SCZenz 16:43, 29 November 2005 (UTC)
Intense magnetic fields will distort and compress electron orbitals, stretching them along the magnetic field lines. This only becomes significant near neutron stars and especially magnetars.
Atomic nuclei only really explode due to radioactive decay (by the weak interaction). Nuclei forced close enough together for the strong interaction to overcome the electrostatic force will undergo some kind of nuclear fusion. ‣ᓛᖁ♀ᑐ 19:57, 29 November 2005 (UTC)
In the most extreme case, hypothetically strange matter will form, as quarks fuse together to become one big nucleon. Finally if it is really really extreme compression, you get a black hole. -- Natalinasmpf 22:00, 29 November 2005 (UTC)

[edit] LISP

How can I get common LISP running on my windows XP laptop? And how can I make my lisp programs available over the internet?

Our article on Common Lisp lists a number of implementations that are freely available; two of them state that they'll run on Windows.
If you want to distribute your software, you'll probably want to host it on a website. If you decide to use an open source license, SourceForge.net will provide free hosting for your project. Otherwise, you'll need to find some other site that will handle the distribution for you, or set up a website yourself. —David Wahler (talk) 16:42, 29 November 2005 (UTC)
Check out Lispbox, an easy-to-use package that contains everything you'll need to start using Common Lisp.  Grue  17:45, 30 November 2005 (UTC)

[edit] MEDICINAL PLANTS

See Category:Medicinal plants or ask a question. This page is not a search engine, that is the box on the left convieniently labeled "search". Thryduulf 22:29, 29 November 2005 (UTC)

[edit] pi as a limit?

I've been trying to express pi as the limit as n goes to infinity, where n is the number of sides in a polygon. From what I've figured, it would be the ratio of the perimiter to the length of the longest diagonal. However, as I haven't used geometry for several years, I can't seem to express it mathematically. Please help and explain when neccessary. Thank you. --frenchman113

You can certainly do this, but what is your aim? The answer is going to turn out to be a limit of a trig function. Pi can easily be gotten from trig functions by 4*atan(1) for example, but those functions need to be evaluated by various infinite series, so I'm not sure what you're aiming for. Do you just want the exercise of figuring out the trig way of doing it, or is this a homework problem? For starters have a look at trigonometric function and maybe exact trigonometric constants. The trick to make the numbers easier is hold the length from the center of the polygon to a vertex as one, then pi is the ratio of the circumference to 2, where the circumference is the sum of the lengths of the sides. To get your right angle to use for the trig identities, consider the line from the center of the polygon to the center of one of the sides (it makes a right angle). Pick the right trig function and think about which side is which and what angle you have in relation to how many sides you have, and you'll get your answer. I've forgotten enough trig that it was a fun exercise to do. Yes that makes me a bit off in most people's eyes :). If you want more ways to express pi as a limit of an infinite series, etc, pi has tons of those. - Taxman Talk 19:40, 29 November 2005 (UTC)
It could possibly be the beauty of a pi limit ... I mean, I've sought equations that make smiley faces on Cartersian graphs. ;-) I've concluded this is possible, considering how close I've come to making one. -- Natalinasmpf 21:58, 29 November 2005 (UTC)

First of all, I won't use diameter, because most polygons don't really have well-defined diameters. Even with regular polygons, if the number of sides is odd, diameters are tricky because they go from vertex to side, rather than vertex to vertex. I'll use a radius r instead (defined to be the length from the center to a vertex). So, for a regular polygon with n sides, each side of length s is subtended by an angle of

\theta=\frac{360^\circ}{n}

since there are n equal such angles. Using the law of cosines, the length s is given by

s2 = 2r2 − 2r2cosθ.

Solving and simplifying gives

s=r\sqrt{2}\sqrt{1-\cos \theta}.

The total perimeter of the polygon is Pins=ns. I may then consider the ratio Pins/2r:

\frac{P_\mbox{ins}}{2r}=n\sin\frac{180^\circ}{n}.

This formula gives a lower bound for π, since it applies to a polygon inscribed in a circle (which has a shorter perimeter than the circle). If I consider a circle circumscribed by a polygon, using similar methods, I get

\frac{P_\mbox{circ}}{2r}=n\tan\frac{180^\circ}{n}.

Thus I conclude that

n\sin\frac{180^\circ}{n} < \pi < n\tan\frac{180^\circ}{n}

and that

\lim_{n \to \infty} n\sin\frac{180^\circ}{n}=\lim_{n \to \infty} n\tan\frac{180^\circ}{n}=\pi.

You can use this formula to get approximations of π using the half angle formulas. I believe that this is the method that Archimedes used. Hope that helps. -lethe talk 23:34, 29 November 2005 (UTC)

I've gotton a headache reading this, but trig is fun and I'll live. Thanks a lot.--frenchman113

[edit] Neurological diseases

Have any neurological diseases (similar to Huntington's, Alzheimer's, or ALS) ever been cured?


Marianne


18:59, 29 November 2005 (UTC)

Most progressive neurological diseases are considered "incurable" due to either the limited ability of neurons to repair themselves, or limited knowledge of the pathogenesis of these diseases. The closest thing to a cure I can cite is the limited success in treating Parkinson's disease with the implantation of fetal stem cells. The fact that this has happened at all is perhaps due to the relatively extensive knowledge of the biochemical basis for the symptoms of this disorder. See: Fetal Brain Cell Transplants Benefit Some Patients with Parkinson's. Of course, the issue of fetal stem cell use is rife with ethical and religious questions, which will probably limit the usefulness of this method as a means of dealing with neurological disorders on a wide scale. --
Mark Bornfeld DDS
dentaltwins.com
Brooklyn, NY 20:01, 29 November 2005 (UTC)

[edit] Medical Doctor

Hello there,

Thank-you for taking the time to read this. I am wandering at which year does a student wanting to be a doctor start to get paid-during the internship, perhaps? I am in Alberta, Canada, but I trust it is similar throughout North America.

I appreciate this.

R. Fernando

Yes, the pay starts after graduating from medical school, and getting accepted to a residency position. The first year of residency is often called the intern year. The pay though is pretty low considering the work and the years of schooling. I'm sure it varies by the program, area, etc., but most residents I know make USD$40-50k for >80hrs a week of work. It basically makes the residents cheaper than the nurses, so the residents get worked as hard as the hospital can get away with it. - Taxman Talk 19:46, 29 November 2005 (UTC)
Oh, and of course we have articles (2 that need to be merged) on that residency (medicine), and medical residency, that explain a bit more accurately than I did, that internship can actually be separate from residency in some cases. - Taxman Talk 19:54, 29 November 2005 (UTC)

[edit] Earth ground versus neutral line

Electrically, what is the difference between an earth ground line and a neutral line in standard US utility systems? I ask because I am working with a 120VAC switching power supply that outputs 24VDC on one line and ground on the other, and a device I am using still requires a separate earth ground. The mfr even went so far as to design the supply to obstruct the ground pin on the outlet so it could not be used for this purpose. It was my understanding that the ground line and the neutral line were ultimately tied to the same place (a true earth ground like a copper pipe emerging from underground), and extend outward separately in the utility network as a safety mechanism, the ground being for device faults to shock the utility and not the user. If this is true, why do I not get +24V when measuring from the positive on the power supply to the earth ground line? Is this a sign of a bad ground? --Jmeden2000 22:47, 29 November 2005 (UTC)

Is Ground and neutral of any help?--Commander Keane 06:06, 30 November 2005 (UTC)
In the UK, part of the electrician's job of testing an installation for safety is confirming absolutely that the ground (UK, "earth") and neutral are not connected to each other. So some people think it's pretty important. Notinasnaid 12:38, 30 November 2005 (UTC)
Maybe i'm looking for too complicated an explanation, but i cannot find anything that talks about the true differences in neutral line/ground line/earth ground when used in practical applications with power supplies (transformer/switchmode). Most specifically, what are the electrical potential differences in the three, and in a switching power supply, what is the difference between it's negative output and the three types of grounds? --Jmeden2000 15:19, 30 November 2005 (UTC)
They are typically exactly the same, electrically. The problem is that you are looking at this from a purely electrical point of view. The earth/ground is not there to provide any electrical function whatever, in normal use, and all devices (unless faulty or including very sophisticated checking) will work fine if the earth is disconnected. The earth is there for safety.
Because electrical appliances are not always used in ideal conditions, well maintained, or kept away from the foolish, the safety systems are designed to have multiple points of failure. This is why you cannot substitute neutral for earth, or earth for neutral, because that would become a single point of failure.
If an appliance has earth output, it must connect to earth input, and have no electrical connection to any of the other inputs. Notinasnaid 18:11, 30 November 2005 (UTC)
As a follow up, should there be voltage potential between the output of a power supply running on the hot/neutral lines and the ground or neutral lines? I am wondering mostly how to test for a proper earth ground. thanks for the info!
Ground is not neutral. There will be 100-120Vrms from H to N. N to G often has voltage. A DC power supply should ideally be isolated from hot and N. If it isn't I would toss it out. You manually connect ground to positive or negative, to make a positive or negative going DC supply. Dominick (TALK) 19:08, 30 November 2005 (UTC)
I think the test would be with the appliance DISCONNECTED (a) make sure that if there is earth input and earth output that they are connected (short circuit); (b) make sure that there is no connection (open circuit) between earth and each power input, including neutral. If there is any measurable resistance between neutral and earth, there is a fault. Notinasnaid 19:38, 30 November 2005 (UTC)
Ground is supposed to be your local guarantee (it is not an absolute guarantee in real cases). The neutral line can vary from real ground voltages, often by several volts, depending on the details of the installation. Several volts might seem a small amount, but the internal resistance of the ground line should be low (in the order of tens of ohms) and so you can still get quite a shock from a neutral-ground contact if you are unfortunate enough to be in the middle of it. The shock is not usually fatal, but is potentially serious enough for regulators to impose rules to make it uncommon.
To make another description, would you willingly touch the terminals of an automobile battery? The volatge is higher (12 V as opposed to 2–3 V for most neutral-ground accidents), but the resistance of the battery is higher as well. Most adults do not die from accidentally touching the two poles of an automobile battery, but they tend to remember the experience! Physchim62 (talk) 11:58, 4 December 2005 (UTC)

[edit] Kepler's Third Law regarding different masses

moved from Talk:Kepler's laws of planetary motion

How would one go about calculating how long an orbit would be for a star with a different mass than the Sun? Is it as simple as if the sun had half the mass, a year would be twice as long? What about if the planet had a deferent mass? Would a planet with three quarters the mass of earth orbiting a star with half the mass of the sun at 1 AU have an orbit 2.7 years long? Or is it not that simple?

1 AU = 1 year
0.5 (star mass) / 1 year = 2 years
2 Years / .75 (planet mass) = 2.7 years

Thanks, Zhatt 22:54, 29 November 2005 (UTC)

The section on the third law includes the general version:
T^2 = \frac{4\pi^2}{G(M + m)} \cdot a^3
So if M = 0.5MSun and a = aEarth, then T = \sqrt2\, T_{Earth} \approx 1.4\, T_{Earth}.
—wwoods 23:34, 29 November 2005 (UTC)
Thanks Wwoods. I just noticed that version a moment ago, but this still helps a lot in trying to work with it. I'm horrible at math. Zhatt 23:36, 29 November 2005 (UTC)
Sorry, I'm still not quite understanding. Why does T equal the squareroot of 2 earth years? Where does the 2 come from? Don't we also still need to know what m is? Zhatt 23:58, 29 November 2005 (UTC)

OK, I just found this under Orbital period for a "small body orbiting a central body" (the mass of the planet is insignificant).

T = 2\pi\sqrt{a^3/\mu}

and

\mu = GM \, (standard gravitational parameter)

where:

I just don't understand how to insert the numbers. What units do I use? Can I use a ratio of the sun (0.5) for the mass and astronomical units for the orbit's semi-major axis? Zhatt 00:25, 30 November 2005 (UTC)

In T^2 = \frac{4\pi^2}{G(M + m)} \cdot a^3, you would insert SI units, so metres, seconds, and kilograms. For your example, we can ignore the mass of the planet, m, because it is so small in relation to the Sun's mass. Since the square of the period is inversely proportionate to the mass of the system, halving the mass of the star would increase the period by a factor of \sqrt{2}.
If we have the Earth and the Sun, then we have {(1 \ year)}^2 = \frac{4\pi^2}{GM} \cdot {r}^3, where M is the Sun's mass (we ignore the mass of the Earth) and r is the radius of the Earth's orbit (assumed circular). For your example, we have {(x\ years)}^2 = \frac{4\pi^2}{G\frac{M}{2}} \cdot {r}^3. We now divide the equations by one another, giving: \frac{{(x\ years)}^2}{{(1 \ year)}^2} = \frac{\frac{4\pi^2}{G\frac{M}{2}} \cdot {r}^3}{\frac{4\pi^2}{GM} \cdot {r}^3}, or x2 = 2, and therefore, x = \sqrt{2}. --Borbrav 01:21, 30 November 2005 (UTC)
Thanks, I'm think I'm starting to understand. So if the mass of the star was .7, or M/1.4, would x = \sqrt{1.4}? Ohkay, but what if we wanted to change r too? Since we've been using factors of the Sun, could we use factors of an AU too? How would we find the orbital period of a planet orbiting a star at .3 AU with a mass of .7 Suns? Does anyone know where I could even find a calculator where I simply enter these units (SI or not) and get the period? Thank you very much, Zhatt 19:00, 30 November 2005 (UTC)
Google Calculator is great for these sorts of calculations, because a) it automatically does unit conversion if you use different units, and b) it has a lot of useful constants already in it, which you can just express as words or sometimes symbols such as the mass of the sun or astronomical units. So, using the formula Zhatt gives above:
orbital period around star with mass of 1 sun and semi-major axis of 1 AU (note: not exactly one year since an astronomical unit is defined in terms of the Gaussian year, which is not exactly one year.)
orbital period around star with mass of 0.7 suns and semi-major axis of 0.3 AU.
If you don't like the units it provides the default answer in, just append "in [units]" to the end of the expression, for example, the second answer above in seconds.
Alternately, we already found above that the orbital period is inversely proportional to the square root of the mass of the orbited body, and we know from Kepler's third law that the square of the orbital period is proportional to the cube of the semi-major axis, or the orbital period is proportional to the semi-major axis raised to the 3/2 power. So a planet orbiting a star with the mass of 0.7 suns with a semi-major axis of 0.3 AU would have an orbital period of (0.7)-1/2(0.3)3/2, or ~0.196, that of earth's. Chuck 22:12, 30 November 2005 (UTC)
That you so very much! That's exactly what I needed! I was trying something similar, but I didn't know how to enter it in. Today I learned something about orbital mechanics, units, and math! I just love Wikipedia! Thanks again everyone. Zhatt 23:47, 30 November 2005 (UTC)

[edit] Liquids

Does anyone know if any of these are non flammable?

If you can help me..thanks. :)

Ammonia, ethanedial, and ethylene glycol are usually not flammable; hydrochloric acid and nitric acid are certainly not. All of the rest are (and, incidentally, would probably ignite or explode on contact with the nitric acid). ‣ᓛᖁ♀ᑐ 23:39, 29 November 2005 (UTC)
Ammonia is somewhat flammable, its article states it has a flammability rating of 1 - that is, it must be preheated for burning to occur, ie. just taking a match to it won't do much, it needs to be heated apparently so a significant amount of it becomes flash point temperature...plus it has all those hydrogen atoms anyway, I believe production of nitric acid uses ammonia to produce nitrogen dioxide while simulteneously using it as a fuel to produce heat... -- Natalinasmpf 01:59, 30 November 2005 (UTC)


Hey thanks! I really needed to know that.

[edit] Powder/ Another question

For class I have extracted this powder from a mixture by boiling. And it's a bright blueish green color. But it got me thinking...our mixture is also a blueish green. Could there be by any chance some type of food coloring or something turning this powder green?

It's possible, but there are many blue chemicals. Would the powder happen to be a copper compound? ‣ᓛᖁ♀ᑐ 00:40, 30 November 2005 (UTC)


Copper is actually one of the things listed that it could be. Are there any other characteristics of copper that could be used to identify thats what it is?? :)

If you have access to a science lab, you might want to try the flame test on your sample. Copper compounds tend to produce a green or bluish-green flame. Or, you can dissolve it in some water water and add sodium hydroxide; if this produces a blue precipitate, it's almost certainly copper. —David Wahler (talk) 01:18, 30 November 2005 (UTC)


Oh, we did a flame test, and I belive the powder turned the flame orange. But we could have did something wrong, geuss I don't really know. :-P

Sodium compounds--including ordinary table salt, NaCl, result in a very vivid orange color in a flame test. The orange from the sodium is so bright it tends to overwhelm any other color that may be present. So if you really do have a mixture, it's possible that it has a sodium compound as well as a copper compound in it. Chuck 22:15, 30 November 2005 (UTC)

[edit] AOL installation dies on me

What's up with these errors?? I have no idea why i'M getting them, AOL has always installed just fine in the past (AOL spyware not withstanding), and now everytime I start the process I get these..
Image:AolBAD.jpg
this
&
Image:AolBADw.jpg
followed by this one, then a crash
As an alternative, would anyone know where I can find a much older aol installation? online? something like AOL 5.0 or 6.0, so I don't have to put up with all the addweary goodness that is 9.0b-SE--Aolanonawanabe 23:49, 29 November 2005 (UTC)
  • bump* I forgot to mention I'm in a hurry--Aolanonawanabe 00:18, 30 November 2005 (UTC)
Well, I can't help with the error message, but there appears to be an AOL 5.0 version for download at this site. I've never used it before, but it looks to be fairly legitimate. --ParkerHiggins 01:06, 30 November 2005 (UTC)
  • I don't suppose you'd know off the top of your head, if AOL 5.0 had support for cable/DSL?--Aolanonawanabe 01:20, 30 November 2005 (UTC)
Well, a quick google determined that "AOL 5.0 has resident broadband support capability" (from this site with the annoying pop-up). I think that means you're a go, but I can't be sure. You can check on the article, if you're in doubt. --ParkerHiggins 01:27, 30 November 2005 (UTC)
Installation worked, this time crashed after installation finished
Image:Thisclose.jpg
so close
, thanx anyway though--Aolanonawanabe 02:11, 30 November 2005 (UTC)
Might I ask why AOL? --frenchman113

[edit] November 30

[edit] Re: Computer Aracana...

merged with #Computer arcana for the web.tv user above —David Wahler (talk) 03:20, 30 November 2005 (UTC)

[edit] Royal Society of London

I would like to know how the Royal Society of London first discover that oxygen was responsible for the change of color of blood in the lungs?

After people like William Harvey develop the idea blood circulation, many people became concened with the change of color of blood in the lungs. Royal Society members Robert Boyle and Robert Hooke suggested that something from the air ("aerial nitre") was picked up in the lungs and accounted for the color change. People like John Mayow are often credited with recognition of "oxygen" (under different names) before the term "oxygen" was used by people like Joseph Priestley. A search of the internet for (Boyle Hooke lungs blood) will lead to some webpages that describe some of the early observations that were made and experiments that were done. --JWSchmidt 03:03, 1 December 2005 (UTC)

[edit] Measuring Electromagnetic Radiation (EMR)

Two part question:

What type of instrument is used to measure the amount of EMR put out by a small appliance.

What types of flexible matierials block EMR (i.e., mesh, aluminum, kevlar)?

Thank you. Crillion 14:15, 30 November 2005 (UTC)

Here is the answer to the second question. Wire meshes are effective materials which shield objects from EMR. When an object is enclosed by a wire mesh or is inside a metal box(which can be of aluminium foil), electromagnetic waves cannot enter the mesh or the box. This can be easily observed. If you wrap your cell phone in a wire mesh, you can see the signal gradually decreasing in strength and eventually dying out. This is the technology used in coaxial cables used in short range communication to prevent external disturbances. Of course, wire meshes can not shield against EMR of high frequency such as light but is effective in the radio frequency range. When a source of electromagnetic radiation is enclosed in a wire mesh, there is no obstruction to the outgoing EMR.Vishnu Pradhan.V 17:57, 30 November 2005 (UTC)

See also Faraday cage. Chuck 22:17, 30 November 2005 (UTC)

[edit] human body

what are the basic differences between enzymes and hormones?

Enzymes are catalysts; hormones are biological messengers. —Keenan Pepper 16:16, 30 November 2005 (UTC)
Typically, enzymes are proteins or nucleic acids that act as catalysts to facilitate a reaction to occur on a biologically useful time-scale. Many scientists contend that for a molecule to be a true "enzyme," it must be able to perform catalysis many times (multiple-turnover). However this is not wholly agreed upon.
Hormones are molecules that conduct signals through the body often from one type of tissue to a wholly different type of tissue. Some hormones have widespread effects in a variety of tissues. Hormones may be peptides, sterols, lipids, or other small molecules. IlliniWikipedian 19:21, 30 November 2005 (UTC)

[edit] microwaves

are the microwaves dangerous

Microwaves are not dangerous at any level you would normally be exposed to (e.g. from cellphones). Because their frequency is relatively low (lower than that of visible light), they are not ionizing radiation and they can't cause cancer or radiation poisoning. If you were exposed to a large amount of microwaves (e.g. from a microwave oven tampered with to run with an open door), your flesh would simply heat up and you would be burned (which makes sense because that's exactly what a microwave oven uses them for). —Keenan Pepper 16:09, 30 November 2005 (UTC)
I think the proper term would be 'you get boiled '. Unlike in a normal oven the heat doesn't come from outside, but the microwaves heat up the water in your hand. I wonder now, how would that feel? I suppose that since the body is not accustomed to (hasn't evolved with) this sort of phenomenon you'd get serious damage before you start to notice it getting uncomfortable. The sensors are only present in the skin and normally when they start to notice the heat it has only started to get through to the flesh under it and there is usually still plenty time to react. Not so with microwaves. DirkvdM 16:57, 30 November 2005 (UTC)
While technically the danger from microwave exposure is the result of tissue heating, keep in mind that some tissues are more sensitive to damage from microwave energy than others. It has been known since World War II that those heavily exposed to aviation radar developed cataracts. Recently, some police organizations have questioned the safety of occupational exposure to hand-held speed radar guns, suggesting a connection to various maladies from decreased fertility to testicular cancer. See: OCCUPATIONAL EXPOSURE OF POLICE OFFICERS TO MICROWAVE RADIATION FROM TRAFFIC RADAR DEVICES.--
Mark Bornfeld DDS
dentaltwins.com
Brooklyn, NY 17:13, 30 November 2005 (UTC)


As an engineer who works in this field, I have to say many of those cases are overstated. The suspected cataract link can't show changes to the lens before a cataract from microwaved eyes. I can tell you from direct experience, microwaves do not penetrate deeply due to the skin effect. Skin effect burns are painful, and more intense IMHO, than other types of heating burns. Microwave heating also is bad in the genitals, especially males (do the math), and direct microwave exposure should be avoided there. A simple sheet of aluminum foil will do wonders if you suspect microwaves are bombarding you. Dominick (TALK) 18:19, 30 November 2005 (UTC)

[edit] jpeg entrophy coding

What is the advantage of entrophy coding?How does it actually work?Why is it used for loossless compression? I.T.

Try Entropy encoding Jpeg#Entropy coding and lossless data compression Dominick (TALK) 18:22, 30 November 2005 (UTC)

[edit] Simple Wiki

The Wikipedia Help mailing list has received an e-mail from Darrell seeking information about wiki's.

I would like to create a simple, Windows based wiki for a fantasy dictionary I am writing. I want to have it be local to my machine at first and eventually published with the ability to allow only certain users access to editing. I have searched and searched but I can’t find anything that is not horribly complicated to set up. I don’t want to have to mess with LINUX, and the documentation I have found for most of them is written in a strange geek language I can’t make heads or tails of, and seem to assume I already know how to do it. I’m getting no help from the local open source people. Where can I go to get some help?

I referred him to our Wiki article. However, I would also be grateful for any advice you could give him. Capitalistroadster 17:53, 30 November 2005 (UTC)

  • I looked at a list of Wiki hosts and found that http://www.schtuff.com/ is a free Wiki host that allows you to customize your permissions. Does that do the trick? If you really must run your own server, here is a comparison chart of Wiki servers. Most of them at least nominally run on Windows, but no doubt some are easier to set up than others. rspeer 00:31, 1 December 2005 (UTC)

[edit] Question about walking disability

On my way home from the office this evening I noticed a gentleman, about in his thirties, walking very oddly. His feet were turned strongly inward, knees bent outward, and the legs never seeming to become fully extended. His body was swaying, and twisting very strongly about the vertical axis with every step. He was not drunk or anything (at least I don't think so), it looked like had to walk this way because of a disability of some sort. It's not the first time I've seen people walking like this, and it looks very painful. I was wondering - does this particular condition have a name? Is it treatable? Thanks for any information! — QuantumEleven | (talk) 18:13, 30 November 2005 (UTC)

  • There are many conditions that cause ataxia, and the person you observed might have any one of them. Perhaps the most common congenital cause is cerebral palsy.--
    Mark Bornfeld DDS Brooklyn, NY 19:42, 30 November 2005 (UTC)

[edit] Geckos

The Wikipedia help list has received the following query from a reader concerning geckos.

In southern Colorado we've noticed geckos around our outside at times. The problem is that one or more have found their way inside, particularly in the downstairs family room. As you know, they are rapid and almost impossible to catch, especially by two octogenarians such as my wife and myself. Any suggestions you might have for getting rid of them would be greatfully appreciated.

I have suggested contacting the Colorado Division of Wildlife or his local council for assistance. I would be grateful for any suggestions that you might have.

Capitalistroadster 18:42, 30 November 2005 (UTC)

Lizards are beneficial. When I was single, I let pet shop geckos loose in the house to eat our common florida cockroaches. Are you confusing them with skink lizards? I am too much of a reptile lover to assist in a lizard death! Most are not poisonous, and they will not crawl on you in the middle of the night. Dominick (TALK) 19:11, 30 November 2005 (UTC)

That was also my first reaction. Why would you want to get rid of them? Geckos are fun animals and I've never heard of them being harmful. Unless you find their call annoying, which would make you the first one in my experience. And Dominick, why would getting rid of them have to be lethal? You might just catch them and move them elsewhere. Or find out what they like and lure them away. Which brings me back to the original thought. They feed on insects, which might be attracted by the lights in your house, which in turn attracts the geckos. Which makes them a pest control, not a pest. Of course this line of reasoning isn't friendly on the insects, but then you can't have it all. :) DirkvdM 08:53, 1 December 2005 (UTC)
Yeah, in Texas we always loved having our geckos and anoles around to eat up all the annoying bugs. Just the fact that they're in your house shows that bugs are getting in somehow, so might as well let the little guys take care of them. — Laura Scudder ☎ 04:06, 2 December 2005 (UTC)

[edit] Geckos

How are geckos born? We live in San Antonio, Texas. We have many Geckos around our house. We found a group of about 15 oval, thin, translucent shelled eggs approximately 1/2" long, in our attic.

I found a Texas Banded Gecko site with egg pictures. [70] Dominick (TALK) 21:23, 30 November 2005 (UTC)

[edit] Technology

What is the name of a complicated devise designed to do a simple task?

  • Perhaps Rube Goldberg is what you're thinking of? -- TheArchivist 20:18, 30 November 2005 (UTC)
Or the related British term Heath Robinson smurrayinchester(User), (Talk) 20:21, 30 November 2005 (UTC)

[edit] Sativa

The species name Sativa appears in the binomial names for several, unrelated, plant species (including Cannabis sativa, Allium sativum, and Oryza sativa). Entirely coincidentally, I notice our redirect sativa is up for deletion (seems sensible, given that it's not just cannabis). Does sativa merely mean "domesticated"? -- Finlay McWalter | Talk 20:31, 30 November 2005 (UTC)

Sativa is Latin for useful. —Keenan Pepper 20:34, 30 November 2005 (UTC)
Actually scratch that. It means sown or domesticated. I was thinking of something else... =) —Keenan Pepper 20:38, 30 November 2005 (UTC)
Thanks Keenen. I see you made it a disambig page - I did a site-specific google and found a whole bunch more. Had I known about it, I'd have looked in the excellent List of Latin and Greek words commonly used in systematic names, which explains this and much else too. You may wish to cast a vote at Wikipedia:Redirects_for_deletion#October_23, btw. -- Finlay McWalter | Talk 21:44, 30 November 2005 (UTC)

[edit] SAX

What is the SAX dangerous properties and environmental fate handbook? Is it the same as Sax's Dangerous Properties of Industrial Materials? ‣ᓛᖁ♀ᑐ 21:02, 30 November 2005 (UTC)

[edit] Theobromine toxicity

Where can the RTECS entry for theobromine be found? ‣ᓛᖁ♀ᑐ 21:14, 30 November 2005 (UTC)

Since RTECS is a for-pay database, you're unlikely to find the information out for free on the internet. Information on various ways to pay for access can be found here. Your best bet is probably to check with your local public or university library to see if they have access to the database. Chuck 22:23, 30 November 2005 (UTC)
The RTECS number is XH2275000, you could try looking on PubMed but there are nearly 4000 responses... Physchim62 (talk) 12:24, 4 December 2005 (UTC)

[edit] Fiber Optics

What type of degree must you have to be able to work in the field of fiber optics?

It is a pretty wide field. I got my M.S.E.E. and wrote my thesis on a fiber optic principal. I taught students who got a technical school degree and work in fiber optics spicing cable. What do you want to do? Dominick (TALK) 01:09, 1 December 2005 (UTC)