Wikipedia:Reference desk archive/Science/2006 July 5

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[edit] How did the mammalian ear evolve?

And what did it actually evolve from? Ear doesn't provide that information. Much help appreciated ! Xhin 00:04, 5 July 2006 (UTC)

ISTR that the bones of the ear evolved from the structures in gills - the following google search reveals many possible references for that. Grutness...wha? 01:08, 5 July 2006 (UTC)
The talk.origins archive has an excellent article [1] that happens to mention the development of the mammalian ear from the reptile jaw bones. —Bradley 15:07, 5 July 2006 (UTC)

[edit] Camellia Sinensis growth area

Does Camellia Sinensis grow well in the Pacific Northwest of the United States? In particular I'm referring to area that falls in gardening zone 8. Jumbo Snails 00:36, 5 July 2006 (UTC)

Probably not - as the article says, it is cultivated "in tropical and subtropical regions". -R. S. Shaw 07:33, 9 July 2006 (UTC)

[edit] Being a biology searcher

Hi!

I'd like to know: what's the salary of a biology searcher?

Also, in which specialisation in biology should one go if he wants to do research in complexity/emergence, i.e. the kind of work Stuart Kauffman is doing?

Thanks!

Salaries for biological researchers in academia tend to be pretty low until one reaches the level of professor. Lets assume you are talking about the USA. The during your PhD training you may receive a salary of around $25,000. This will be for between 4 and 7 years. Then, as a post doctoral researcher you may receive a salary of something like $31,000 to $45,000 depending on experience, field and location [2] [3] [4]. 2006 NIH guidlines are slightly higher ($37,000-$51,000 [5]), but not everyone has caught up to them yet. This period may last from 3-7 years.
After that, if you are talented and lucky enough, you may become an assistant professor. In this stage salaries can vary greatly but you may start on something like $50,000 all the way up to $100,000. After you earn tenure and become a full professor, your salary can rocket. I know a few Prof's who are on well over $250,000 basic salary, not including various industrial and commercial interests which may double that again.
In terms of Stuart Kauffman's research. Well, the very nature of complex systems means you can tackle it from may different perpectives. Perhaps evolutionary biology, genetics or molecular biology might be a good place start. Rockpocket 01:24, 5 July 2006 (UTC)
(edit conflict)
Biology researcher? Most work in academic or corporate settings. Salaries tend to vary by level of training and by setting (and enormously by country of course). In the US, you can work in a lab with a BS in many different sciences and typical salaries are maybe $30-80,000. Corporate labs can be higher and independent research institutes somewhere in between. To do original research (rather than carry out someone else's projects) and run a lab, you usually need a PhD in one of many different sciences. As your academic standing increases and your research prospers you earn more, but few full professors have base salaries above the $80-180,000 range. There are rare exceptions where someone invents something and becomes rich or becomes a biotech entrepreneur and becomes rich but most biological researchers don't get rich.

Kauffman is an example of someone who does research that crosses several scientific disciplines so his original degree or training is not so important. If you want to head in that direction, start with a lot of math, chemistry, and biology, take more of the stuff you find most interesting, and when you get to university look for opportunities to work (courses, independent study, or even part-time employment) in the labs of the people doing the research that attracts you. By late university you should be developing the contacts that get you into graduate school and a lab or research group doing what you want. That is the typical roadmap. Good luck. alteripse 01:30, 5 July 2006 (UTC)

[edit] a compound

Can someone identify the compound before the reaction and after the reaction?

http://www.umit.maine.edu/~miljkovic/S295E7C69.-1/compound.jpg?WasRead=1

Thank you!

130.111.240.124 02:23, 5 July 2006 (UTC)

Repeat after me: "I will do my own homework". -- Koffieyahoo 04:49, 5 July 2006 (UTC)
"I will do my own homework". DirkvdM 06:26, 5 July 2006 (UTC)
"Koffieyahoo will do his own homework". I don't think I did that right... 128.197.81.223 16:18, 5 July 2006 (UTC)

[edit] Computer Hardware

1. Why do computers fail less frequently than copy machines and printers? 2. Do large computers such as mainframes and supercomputers have a future?

Computers fail less frequently than copy machines and printers? News to me. If you're talking about jamming, mechanical parts can jam, purely electronic parts can't, but it's entirely possible for a computer's fans to jam, and the computer itself to overheat. There are safeguards in place to prevent this, however. --ColourBurst 03:03, 5 July 2006 (UTC)
Sounds like homework to me. BenC7
The fewer moving parts something has, the longer it is likely to go without maintenance. (That's hardware maintenance of course. The software is much more fragile.) My PC is seven years old and has only had a fan replaced. But we call the maintenance man to attend to the photocopier every few weeks. --Shantavira 06:24, 5 July 2006 (UTC)
Mainframes are the future I think. If everyone has a computer that uses just a tiny fraction of its computing power, then why not use one computer for a whole block? The savings would be so enormous that you could easily hire a professional to run it for you, so you wouldn't need to worry about installing software (just ask the guy and the whole block will be able to use it) or safeguarding against viruses and stuff. Actually, I'm surprised this is not already the standard. The concept is old, it just needs to be applied in a different environment. Of course all the software can be free because the admin knows how to use Linux and stuff.
Let me do the math. Say an average computer user spends 100 euro per year on new computers and that 100 people decide to band together (both low estimates). That would be a saving of 10.000 euro per year. Given that the admin won't quite have a full time job doing this (yes?), that should cover his wages. In return the users get safety and save time. And money if there's more of them who would normally spend more on computers. DirkvdM 06:46, 5 July 2006 (UTC)
The other way to go with all the unused computing power is to harness it as a commercial commercial resource. Just pay people for the use of their computer's resources when they aren't using them, and redistribute the computing power to those that do need it. Crazywolf 07:34, 5 July 2006 (UTC)
The article that will probably add some specifics to your "mainframe" post is distributed computing. It would be apparently pretty hard to duplicate the computing power of the world's most powerful computer (Blue Gene) with distributed computers (assuming System X (computing) can be used as a rough calculation of TFLOPS per computer, it would probably require over 25,000 Xserver G5s to duplicate it, though I don't know if additional costs/benefits become a problem when you are talking about that many computers at once), but then again most people don't need that much computing power (most people are not using their computers to model H-bombs). --Fastfission 16:34, 5 July 2006 (UTC)

It truly depends on your definition of "failure". Is getting a virus and your email not working right a "failure"? --mboverload@ 02:44, 6 July 2006 (UTC)


Frequency scaling was responsbile for the vast majority of processor peformance increases from about 1989 through the last quarter of 2004. However, heat is becoming the dominant factor in processor design. The only real solution to the heat problem is to go to multiple cores.
Thus, the correct answer is that it depends on your defintion of supercomputer. A supercomputer is traditionally defined as being something along the lines of: a number of processors working on a problem in parallel capable of communication across a bus. A properly configured multi-core/multi-processor system is a supercomputer, and yes, they very much have a future. The real problem, though, is that parallel programming is very hard, and the vast, vast majority of code out there is sequential. Raul654 02:53, 6 July 2006 (UTC)

[edit] Business Networks and telecommunications

1. How can a home with internet access become a hotspot? Are there any risks in turning a home into a hotspot? 2. What are the implications of telecommunications for group work?

Please see "Do your own homework" at the top of the page. BenC7 04:09, 5 July 2006 (UTC)

If you list your questions in a paragraph with added context people won't think they are homework. But as for your first question, assuming you mean hotspot in the non-commercial sense, you turn your home internet access into a hotspot by publicly listing your SSID publicly so that people can find it, and not encrypting the data that is sent over it. There are two main risks to doing this:

  1. Other people can intercept and read the information that you send, unless it is encrypted. Most sensitive information that the average person sends(passwords, bank pages, etc.) is encrypted, though.
  2. Another person could use your network to do something illegal, and it could take a little while to explain to the police that it wasn't you who sent that virus out.
Regarding group telecommunications, consider how the work force inter-communicates, and whether or not you have a paperless-office ... people in same building can more rapidly pass stuff to each other than if they are in far flung locations not even connected using same office hours. Second issue is computer insecurity. It is much simpler to protect a central network than all those people home PCs and laptops in transit. User:AlMac|(talk) 18:33, 12 July 2006 (UTC)

[edit] Overpopulation

There are billions of people on Earth. We call this overpopulation. But what is overpopulation? There are probably other species with a higher population. But they're all smaller. One reason for the amount of people is that they're spread all over the Earth, which is fairly unique, I suppose (for a land creature). Or is it? Has there ever been a similarly sized population of animals our size in the history of life on Earth? I've once heard something about a biological rule of thumb concerning the amount of animals of a certain size that an island of a certain size can accommodate. Could this be applied to humans on Earth and what population size would be 'normal' then? DirkvdM 07:03, 5 July 2006 (UTC)

Overpopulation gives the standard definition and a good explanation. In general, a species is overpopulated when it's no longer increasing. In that sense, it is neither good nor bad for a species to be overpopulated, the population will simply decrease to the carrying capacity and be at equilibrium again. When we are talking about humans, though, we generally look at overpopulation as a bad thing. If population is decreasing, then more people are dying than being born, and unless there are birth control measures in place, that probably means lots of people are starving to death or killing eachother.
But, to answer your question, you couldn't make a rule like that. It depends largely on how well adapted to it's habitat the species is, and what it eats. An herbivore or omnivore could support a much higher population density living off of plants than a carnivore could, since it relies on the population density of the herbiovores for food. And you could support a lot more sloths in an acre of rainforest than you could support horses in an acre of grassland. There simply is more food in the rainforest and the sloths use it much more efficiently. As for which animals would have the highest kilogram per sq km, I would go with ants or sloths, but that would be a wild guess.
But you couldn't use that logic to decide on a normal human population. The carrying capacity of Earth for humans is obviously higher than our current population, and that carrying capacity goes up quickly as technology advances and spreads to developing nations. The only problem with that is that our actions that damage the environment are reducing the carrying capacity of the planet at the same time. Crazywolf 07:29, 5 July 2006 (UTC)
We could say that there is overpopulation of humans on earth because the population of humans, as a whole, doesn't have sufficient food/clean water/sanitation. You could argue that is a resource allocation issue but the allocation of food/water isn't going to change dramatically to the benefit of those starving/in drought/dying of poor sanitation throughout the world so I'd say its overpopulation. AllanHainey 13:33, 5 July 2006 (UTC)
Right, I was sort of asking about the 'natural' maximum, but when it comes to humans, 'natural' is something different. Also in the sense of birth control measures (although they don't have to be measures - people can just not be bothered to have kids, like what is happening in rich countries such as in Europe). I now understand there are two types of overpopulation. The official one being "when there is no more population increase". But long before that, things will start to get unpleasant, and a more 'humane' definition would be based on that. It's just a very ill-defined limit. As it gets more crowded, we'll adapt more.
Thanks for helping me get this a bit more straight in my head. DirkvdM 18:12, 5 July 2006 (UTC)
It's not at all clear that "the carrying capacity of Earth for humans is obviously higher than our current population". I assume you say that because you're thinking that the population can't exceed the carrying capacity, but that's not true: it can, but it will eventually crash. (Imagine, for example, graphs of cyclic populations rising far above the carrying capacity, like those here.) Estimates of the human carrying capacity of Earth in a long-term, sustainable mode range from well under a billion to many trillions. For an excellent overview, see Cohen, How Many People Can the Earth Support?. bikeable (talk) 19:38, 5 July 2006 (UTC)
I actually based it on the fact that the rate of population growth is still increasing, and that my(limitted) knowledge of agriculture and natural resources tells me that we can support the world population long term once technology spreads a bit. I understand the cyclical nature of population, but assume that it must be controlled by the fact that some of the derivatives of the equation must become negative as we cross the carrying capacity. I only really considered the third derivative(the rate of increase of the rate of population growth) in my original statement. And I was considering the numerical increase, not the percentage increase, which may not be the best way to look at it. Also, the fourth derivative is obviously negative from the data, which implies that we have indeed passed the carrying capacity. However, the UN stated that this increase is driven by a decrease in birth rate, rather than an increase of death rate, so this might be driven by initiatives to increase the use of birth control rather than a decrease in food availability. So that avenue isn't really that fruitful. After thinking about it in more detail, I admit that it's quite possible that we are past the carrying capacity of the Earth. Crazywolf 23:44, 5 July 2006 (UTC)
Also, I'm not implying that because I don't think we are past the population capacity, we shouldn't try and limit population growth. Decreasing the total population will leave a larger share of natural resources for each person, even if we could support a higher population with them. Widespread replacement level fertility would benefit everyone, even if there isn't an imminent catastrophe. Crazywolf 23:58, 5 July 2006 (UTC)
For a certain population and a given standard of living, there would be a certain maximum stable population. The concept of overpopulation is important because if the carrying capacity is exceeded, the consequent reduction in population will almost certainly be very unpleasant. Peter Grey 23:10, 5 July 2006 (UTC)
As I meant to say above, being at the stable maximum can be unpleasant too. That just means that enough people survive to keep the population stable. It doesn't mean they're having much fun. DirkvdM 09:05, 6 July 2006 (UTC)

I'm probably rehashing what's been said about, but.. Since industrialization, we no longer seem to have a hard maximum limit to the human population, or at least we haven't noticeably reached it.. as the human population continues to grow. We have, however, possibly reached the limit for a human population to live sustainably. The ecological footprint of humans is ever growing, and we're eating into nature's capital. The Earth cannot sustain the current human population with its current energy needs — We can see this in the loss of species (2 or 3 a day, say some estimates) and with the peak oil production being reached, and the massive increase in carbon dioxide and other green house gases in our atmosphere. That said, humans ultimately do not face a problem with finite resources, only with finite thinking. —Pengo 09:52, 6 July 2006 (UTC)

[edit] Cramp

Is Cramp A)Unpleasant B)Noisy C)Useful D)A program E)All of the above. I would appreciate an answer!

The Cramps is b)noisy, http://cramp.wcc.hawaii.edu/Overview/ is useful, cramp is A and C Crazywolf 08:52, 5 July 2006 (UTC)
Isn't this too subjective to have a definite answer? --Proficient 11:26, 5 July 2006 (UTC)
  • The Cramp Twins are both unpleasant and noisy. What is it with these questions? Can't you just simply look up the meaning in a dictionary and pick the answers for yourself? - Mgm|(talk) 12:51, 5 July 2006 (UTC)
  • Not another Clams/Claims post. This should go on RD running jokes. smurrayinchester(User), (Talk) 14:34, 5 July 2006 (UTC)

[edit] bacteria

please anybody tell me the answer and explain it... [1]a bacterium doubles every 20 days.two such bacteria are kept in a space ship and sent away for 1000 earth days.the speed of the ship is 0.9950c.the number of bacteria found after completion of 1000 days are.... [1]128 [2]58 [3]28 [4]64

--203.109.89.194 08:55, 5 July 2006 (UTC)hima

First you have to work out how many days will elapse on the space ship. Since it's travelling close to the speed of light, this will be less than the number of days on Earth. That's the hard part, but presumably you have a formula which will let you calculate it. Once you have this number (call it x days), the number of bacteria can be calculated by working out how many doublings there will be. I think this is 21 + x / 20. Which part of this confuses you?-gadfium 09:08, 5 July 2006 (UTC)
See Special relativity, but the formulae must be T/Gamma, i.e. T*sqrt(1-(v/c)^2) ellol
Another HW question?! --Yanwen 19:34, 5 July 2006 (UTC)

thx for ur reply....ive got the answer....there is a formula to calculate..the number of bacteria after certain period of time using logarithms....u can get that in bacterial growth curve...thks a lot for reply--hima 09:47, 11 July 2006 (UTC)hima

[edit] neuronal and glial vulnerabilities.

i would like information, that is written in words i can understand, on neuronal and glial vulnerabilities as i am having major back surgery on 26.07.06 and this is one of the things that can go wrong as part of a CSF Leak. So far the Doctors have not been forthcoming.

I would only get major surgery from a doctor that is forthcoming. --Rajah 02:29, 6 July 2006 (UTC)

[edit] RGB value of Tyrian Purple

Tyrian purple was the highly prized, ultra-expensive Phoenician dye associated with royalty. But what exactly DOES it look like? Would I be correct in calling it "Royal Purple" and adding a picture of that color to the Tyrian Purple article? --Alecmconroy 10:45, 5 July 2006 (UTC)

Under a new proposal under discussion at Wikipedia talk:WikiProject Color Wikipedia would only contain RGB values if they were from a suitable published standard; you will, however, find a lot of articles at the moment that just have someone's made up (unsourced) idea of what a color looks like in RGB. I don't recommend doing this. A real world photo of something that is agreed to be that color might be an alternative. Notinasnaid 10:51, 5 July 2006 (UTC)
A RGB value is hard to find (I'm still looking), but an example of the color is shown on this pdf. It's apparently a very dark purple, and not especially vivid to my eyes. Oh, and it's not royal purple. – ClockworkSoul 12:07, 5 July 2006 (UTC)
The RGB of the purple in the PDF is #330065 --Kainaw (talk) 14:09, 5 July 2006 (UTC)
I found this on, of all places, Wiktionary. There it is listed as #A8516E, and gives an example
Tyrian purple colour:    
Hope this helps! – ClockworkSoul 12:12, 5 July 2006 (UTC)
Though of course Wictionary isn't a valid source... I would not recommend putting this into Wikipedia, it's only going to be wiped out in time if it is not an RGB standard... Notinasnaid 12:17, 5 July 2006 (UTC)

With all due respect, I do not believe the above color is quite right for the Phoenician Murex-snail-shell dye (I have seen actual material dyed as such). I believe the correct color is more blue-ish. Of course, computer coloration can be misleading as we all have different monitors, brightness/contrast settings, and ambient lighting! I recommend you avoid mentioning an RGB value unless you have a cited source. Nimur 20:59, 5 July 2006 (UTC)

Well, first and foremost, I just want to know the answer. I've been hearing about Tyrian Purple for years, but I realized I don't have the first clue what it actually looks like. Nimur, could you pick a value that seems right to you, if you've actually seen it? As for the RGB thing-- couldn't we show a swatch and say "approximately, more or less, a guess at what the color is"? I mean-- it's going to be different for every viewer- but not THAT different. Definnitely picking one RGB value and saying THIS IS tyrian purple-- that'd be bad. But what's wrong with showing a rough approximating and labeling it as such. --Alecmconroy 03:48, 6 July 2006 (UTC)
You should sort of give up on the idea that Tyrian Purple (or any complex color produced by a biological dye) can be adequately represented as a single RGB value. Tyrian purple ranged from blue to purple, and varied as the result of the particular mollusk species used, how long its hypobranchial glands were dried, and the concentration of the dye, as well as its interaction with the (usually silk) fabric. You might be interested in the article here, which contains spectra of both organic and synthesized Tyrian purple (on the second page of the article). In terms of results (and therefore expense), in increasing order of desirability, one would use woad, indigo, or Tyrian purple. In the middle ages, dyers were limited to particular colors (you would get your blue fabric from one shop, and your red from another). Whole books are written about this sort of thing! - Nunh-huh 04:10, 6 July 2006 (UTC)

This particular dye is based on the Murex trunculus. There are some Jews who believe that this related to the dye used to make a blue string in a ritual garment called Tzitzit. While the exact tradition to how to make the dye was lost over the exile, some have tried to recreate the dye. The dye is purple, but becomes a dark blue after being exposed to sunlit. Here is the full analysis of 6,6-dibromoindigo the chemical the makes the color. Of course an RGB value does not tell you what the color is, but how it would be perceive by a human, see Color vision. Jon513 12:53, 7 July 2006 (UTC)

This web page has some photos of the stuff. According to Paintshop Pro, the average RGB value of the top photo is about #7F467E, which looks like this:
Tyrian purple colour:    
--Heron 21:24, 7 July 2006 (UTC)
The Tyrian purple listed the colored value as #990024. I converted the hex to the RGB value via a program called mIRC and using a mIRC alias. The red, green, blue, value (assuming Wikipedia's Tyrian purple article is correct) is 36, 0, 153. NealIRC 11:33. 17 July 2006 (UTC)

[edit] Command to delete files in Windows / DOS

Is there a command or utility on DOS/Windows to delete the files older than a certain number of days? -- Wikicheng 11:23, 5 July 2006 (UTC)

  • You could do a search on a specific date in Windows and then delete everything with a certain date, but remember to be careful not to include important documents or system files (Windows and important dll files tend to be older than a certain number of days) in such a search. In my opinion it's best to personally check if something is deleteable. If you have determined it is, you can sort items by date and select all files older than a specific amount of time. - Mgm|(talk) 12:48, 5 July 2006 (UTC)

I want to run this as a scheduled batch job, without manual intervention. I remember a (Norton?) utility calls xdel.exe (named after xcopy) which I think offered some flexibility than the dumb del or erase command. I am looking for something like xdel. -- Wikicheng 13:12, 5 July 2006 (UTC)

Not exactly answering the question, but there are great utilities (ARJ, JAR, and others) to backup files past a certain date (with option to remove the originals) ; then just delete the resulting archive. (Not the most efficient, no, but easy.) Peter Grey 23:17, 5 July 2006 (UTC)
I'd install Cygwin and use find, run as a cron job. EdC 23:39, 5 July 2006 (UTC)

[edit] GLOBAL POSITIONING SYSTEM (GPS)

Bold textHELLO EVERONE.

I AM PREPARING A SEMINAR ON GNSS WITH A CASE STUDY ON GPS. PLEASE ANYONE WITH A RELEVANT INFO ON ALL ABOUT GNSS/GPS CAN HELP ME. IT MAY BE A LINK TO A PRESENTATION ON THE TOPIC, OR A BOOK, OR A LIBRARY, OR ANY REFERNCE WHATSOEVER.

I WILL BE VERY GLAD TO HEAR FROM ANYONE. MY THANKS TO ALL.--Akanchawa 11:49, 5 July 2006 (UTC)

DONT TYPE IN ALL CAPITALS!!!! It's the equivalent of shouting. Philc TECI 11:57, 5 July 2006 (UTC)
Maybe s/he is wearing headphones and needs to type louder. BenC7

You should try the wikipedia articles - GPS and GNSS. --Bmk 13:33, 5 July 2006 (UTC)

[edit] Mutagenic but not a carcinogen?

Due to lack of knowledge on my part I've come into contact with Sodium Azide and DAPI (both in highly diluted wash solutions). Due to the low quantities involved and the short exposure times my fellow co-workers in the lab don't think much of it. So I'm not stressing out much right now (have become somewhat wiser though).

What I'm wondering however is how both these subtances, both of which have been used for years, can be flagged as a mutagen but not as a carcinogen? I always assumed that being mutagenic and being a carcinogen is the same?

Places like Pubmed and google give very few answers.

  • edit I always thought that cancer was caused, among other things, by mutations in the genome. So aren't all mutagens possibly carcinogenic?
  • edit 2 Ah yes I understand now. It's like SodiumAzide and seeds? Sodium Azide is proven to be highly mutagenic to plant seeds but I can't find anything about Sodium Azide's mutagenic affect on humans. Same kind of story about DAPI it's quite impossible to find anything related to human studies. I find this very odd because DAPI is a very much used dye in many biological labs. You'd think they do some proper testing on it before letting it be used en mass. Accidents do happen..
  • Mutagenic means the substance causes mutations in your genetic material. Carcinogenic means it causes cancers. While mutations can result in illness not all of them cause cancer. - Mgm|(talk) 12:44, 5 July 2006 (UTC)

Yes - a mutation simply means the genetic code of a cell has been altered. In order for a chemical to be a carcinogen, it must cause mutations that cause atypical uncontrolled cell division. Some good articles too look up are oncogene and carcinogenesis. --Bmk 13:36, 5 July 2006 (UTC)

Both answers are sort of, but not quite correct. A substance is mutagenic when it induces mutations in an in vitro test system, not in you. In other words, a substance labeled mutagenic has not necessarily been found to cause mutations in real people. A carcinogenic substance can cause cancer in a laboratory animal model, but only a very few substances are clearly proven human carcinogens. This may sound like nitpicking but in some contexts these distinctions are enormously significant. alteripse 22:03, 5 July 2006 (UTC)

[edit] 2 Minutes 15 Seconds Until the Next Beat of Heart

Nasa shuttle program manager Wayne Hale says yesterday, about foam particles falling off during take-off, that "Two minutes, 15 seconds is our bingo time. Anytime after that, we're not worried." [6] Why 2m15s?--JLdesAlpins 12:09, 5 July 2006 (UTC)

At that point, the atmosphere is too thin for the foam to cause a serious impact. In detail: Without air, there's no air resistance on the foam. So, there is nothing to push the foam downward and into the shuttle. When the foam comes off, it floats along with whole shuttle for a while and then goes of on a happy course all its own. --Kainaw (talk) 13:18, 5 July 2006 (UTC)
That is what I was thinking at first, but something else in that same CNN article made me wonder about that: "The shuttle reached the lower limits of space a little over five minutes into the flight". Isn't it at the lower limits of space where air density becomes negligeable? If so, then air resistance, especially at the shuttle's high velocity, should still be a factor after 2min15s until 5min. Your thoughts?--JLdesAlpins 15:41, 5 July 2006 (UTC)
See Karman line. --cesarb 17:27, 5 July 2006 (UTC)
I didn't say that there was no atmosphere. I said it was too thin to cause a serious impact. I shouldn't have mentioned "no air resistance". The air resistance is so low that particles falling off don't accellerate much. --Kainaw (talk) 17:34, 5 July 2006 (UTC)

[edit] Molecular biology vs Cellular biology vs Biochemistry

Hello!

Could someone tell me what the difference is between these divisions of biology/chemistry, on the point of view of the jobs?

Thanks!

Did you check molecular biology, cellular biology, and biochemistry? --Kainaw (talk) 14:06, 5 July 2006 (UTC)
Their names describe what field is of particular interest: molecular biology studies life on molecular level, cellular biol. deals with overall life cycle of a cell, interaction of many cell in an organism and with external environment, while biochemistry is concered with chemical changes within a system (let say an organism). However, since all three are concerned with an organism in general, though on different levels, they tend to overlap a lot. For example, biochemist will focus heavily on enzymes (biological catalysts), their mechanism of action, kinetics, thermodynamics, etc. Molecular biologist, will focus on the same enzyme, but will be more interested towards its function in the given situation, i.e. how many bases in a DNA strand restriction enzyme (cutter) recognizes, where will it cut, etc. The three overlap a lot, especially with technological advances, and you can not study one without the other two. As far as jobs go, experience you had previosly in a lab setting is very important, since various techniques are used in all three. In biochemistry and mol. biology you may not encounter so frequenty for example cell fractionation as in cell biology, but we'll employ many many times extractions, purifications, AFLPs, RFLPs, PCR, etc. Hope this somewhat helps..


Svetlana Miljkovic 14:24, 5 July 2006 (UTC)

[edit] Heart stops when sneezing

Hi,

I heard the heart stops when someone sneezes... Is it true??

Thanks!

Yes. [7] Iolakana|T 14:12, 5 July 2006 (UTC)
That's not really a very reliable source... - Mgm|(talk) 07:52, 6 July 2006 (UTC)
No. [8] David Sneek 14:14, 5 July 2006 (UTC)
Cool. I never knew "bless you" stands for "God bless you" (I've never heard anyone using the latter phrase before). I thought they were just nonsense words people got into the habit of saying. --Bowlhover 17:55, 5 July 2006 (UTC)
Do you know why people say "God bless you" after someone sneezes? Because sneezing was a sign of infection with the bubonic plague, and in medieval Europe, if you got the Bubonic plague, you would die. So, if you sneezed, you were probably going to die soon, so people would ask God to bless you so you would go to heaven!
Please, stop telling these bad "jokes" to me. (If you truly believe what you said, can you provide a citation?) --Bowlhover 23:11, 5 July 2006 (UTC)
According to the links Iolakana and David Sneek gave, as well as [9], nobody really knows why people say "bless you" after someone sneezes. --Bowlhover 23:14, 5 July 2006 (UTC)
The only relation I can imagine to be remotely true is a relation between sneezing increasing blood pressure and the heart slowing down to correct for it. That isn't a stopping of the heart though. —Preceding unsigned comment added by Kainaw (talk • contribs)

I heard that the reason for the "God bless you" was that people used to think that sneezing was the soul trying to leave the body. Cite: Someone in my family... -Agito

I've always thought it was interesting that the words "bless you" (english), "à tes souhaits" (french), and "gesundheit" (german) sound like the sound of a person sneezing. I don't think there's any significance, but still it's interesting. --WhiteDragon 14:41, 7 July 2006 (UTC)

The guy that said the thing with the bubonic plague, thats the correct belief from Europe. The guy that said "soul coming out when sneezing" thats also a correct belief, from Rome. -PitchBlack

[edit] Entropy

I read that entropy is not what we learn at school/uni, i.e. the amount of disorder of a system, but how much one ignores about that system. Could someone explain this to me?

Also about entropy, how is it possible that its total sum in a closed system or the universe always tends to raise? It seems strange in this case that everything is not getting uniform... But it must be a false vision of it that I have!?

Thanks a lot!

Entropy is not related to "disorder" as much as to "degrees of freedom" and probability. Entropy is the number of microstates that count as the same macrostate. For example, say you flip a bunch of coins and count up the numbers of heads and tails. You don't care which of the coins are heads and which are tails, just the total number. Then the outcome of half heads and half tails could really be many different outcomes, depending on which specific ones are heads and which are tails, but the outcome of all heads could only be one specific outcome. Therefore we say that the entropy of the half heads, half tails outcome is greater. The positions of particles in a gas is analogous. There are many different ways the particles could be distributed evenly, and much fewer ways they could all be gathered in a corner, so we say the even distribution has more entropy. Does that make sense? —Keenan Pepper 16:16, 5 July 2006 (UTC)

Mmh yes it makes sense, but I still don't understand why the global entropy of universe is always going up :) --Max

What if I only count whether they're all the same? (all heads or all tails) In this case, do ten (or whatever) coins have 1 bit of entropy? (either all the same or not all the same)? Likewise in this case does a single coin flipped have ZERO entropy? 82.131.188.84 20:26, 6 July 2006 (UTC) (not the poster)
The entropy isn't the information you pay attention to, it's the information you neglect. If you flip ten coins and only pay attention to whether they're all the same, then the entropy of the "same" state is one bit and the entropy of the "different" state is a little less than ten bits. I think... —Keenan Pepper 03:32, 8 July 2006 (UTC)

[edit] pruning calamnodin trees

when my small calamondin tree flowers then the small fruits appear, should i take some of them off, leaving only a few to grow? it seems like there are tons of the little fruits! thank you so much, karen

I am not familiar with this variety of tree, so my answer may be incorrect. But in general, when a plant produces a large number of fruits, you may get better size by culling some of the fruits, so the plant can pump all its energy into the remaining fruits. Google may be able to help you with more specific information on culturing this plant. --Ginkgo100 talk · contribs 01:05, 6 July 2006 (UTC)

[edit] Does stainless steel absorb odors?

Can anyone tell me if stainless steel (used in a dishwasher)absorbs odors? We are having trouble with a foul smell coming from our dishwasher and have had Sears service techs out 3 times, and finally a plumber. The plumber told us the problem "could" be the stainless steel has picked up an odor from the dirty dishes? We are skeptical about this. We feel, if this was the case the odor would remain constant but, the odor increases the more days it sits before being run again.

Thanks for your help,

--142.231.69.102 16:29, 5 July 2006 (UTC)

Something caught in the drain, and rotting, seems the most likely to me. Philc TECI 17:20, 5 July 2006 (UTC)
Try running the dishwasher empty and see if the smell continues. It could be that it is not draining entirely and dirty water is being left behind where you can't see it. An empty run would flush it clean (hopefully). The solution may be to just run your dishes regularly and if you plan not to, then run an empty load to clean it out. —Bradley 18:35, 5 July 2006 (UTC)
Stainless steel removes odour, as demonstrated by Stainless steel soaps. -Obli (Talk)? 18:38, 5 July 2006 (UTC)
It's nature's way of punishing you for using such a filthy polluting machine. :) DirkvdM 18:57, 5 July 2006 (UTC)

I suggest a dead mouse is in the dishwasher, not in the sealed waterproof portion, but rather in the part with the motor. StuRat 00:15, 9 July 2006 (UTC)

[edit] Sunburned skin coming off

When I have burned my skin in the sun, after a few days when it has stopped hurting, the outernmost layer of the skin starts coming off so strongly that I can pull it off in large strips, completely painlessly. The skin layer is very thin (thinner than regular paper), white in colour, semi-transparent and extremely soft. I think this is entirely normal, but what is causing this? JIP | Talk 17:05, 5 July 2006 (UTC)

Peeling, caused by sunburn. The article explains more. Philc TECI 17:19, 5 July 2006 (UTC)
I had this, and is not painful, as well as quite disgusting. It eventually goes away, so not to worry. Iolakana|T 17:46, 5 July 2006 (UTC)
You can smooth it out with a moisturizing cream if you want to make it less visible, but as Kilo-Lima said, it goes away. -Obli (Talk)? 18:40, 5 July 2006 (UTC)
I hate putting moisturising cream on it, the little flakes just get caught in the cream and stick to you, and the cram go's all gritty because of this, its horrible. Philc TECI 20:06, 5 July 2006 (UTC)
It may be worth noting that getting sunburned is said to increase the risk of skin cancer. So it isn't just a question of getting sore and getting better, necessarily. Notinasnaid 21:14, 5 July 2006 (UTC)
The article only explained that the UV radiation causes changes in the skin cells' DNA, causing them to die. Does this directly cause peeling, or what causes the cells to disconnect from the healthy cells underneath? And is the layer of skin only one cell thick? A single skin cell would be completely invisible to the naked eye, but I imagine that if there's many thousands of them, they're visible even if they're in the form of a flat layer. JIP | Talk 21:38, 5 July 2006 (UTC)

I am suddenly reminded of Austin Powers: Goldmember, in which the villain, Goldmember, is constantly peeling off pieces of his dried skin and collecting it in a little container. Funny. Disgusting. In fact, here is a quote:

  • Goldmember: (while pulling a piece of skin off himself) Oh yes yes yes, this is a keeper!

- R_Lee_E (talk, contribs) 04:26, 6 July 2006 (UTC)

[edit] Video CDs

I just got The Matrix trilogy off of BitTorrent. Each of the three are 700mb each. How can I burn them onto CDs so that I can watch them using my DVD player rather than having to watch the .avi's exclusively on my computer? --Russoc4 17:52, 5 July 2006 (UTC)

I've used a combination of mencoder and VCDimager. See: Using MEncoder to create VCD/SVCD/DVD-compliant files and www.vcdimager.com. –Mysid(t) 19:29, 5 July 2006 (UTC)
Convert them to mpeg with a program such as Nero. By the way, downloading movies from Bittorent is illegal. --Proficient 09:30, 6 July 2006 (UTC)
Transcoding lossily encoded files is evil. Not to mention stupid.--Frenchman113 on wheels! 13:35, 8 July 2006 (UTC)
Unless he (/she) paid for them. -- User:Mac_Davis
It's not illegal if you don't get caught.--Frenchman113 on wheels! 13:37, 8 July 2006 (UTC)
Or is in a country where it is legal. Jon513 12:34, 7 July 2006 (UTC)

[edit] Clamps

Are clamps A)Metal B)Small C)Liquid D)A tool E)An electronic. I would appreciate an answer!

A tool. Strange question... -Obli (Talk)? 18:43, 5 July 2006 (UTC)
Groan... See #claims, #Clams and #Cramp. smurrayinchester(User), (Talk) 19:08, 5 July 2006 (UTC)

Are these the English homework questions disguised as valid science ref. desk questions? May be we can expect scale, skill, skull, school etc in the next questions?--Wikicheng 03:56, 6 July 2006 (UTC)

[edit] steam catapult

--Kkishappy@btinternet.com 18:38, 5 July 2006 (UTC)please help. who invented the steam catapult?i know they were used on aircraft carriers to launch the 'plane from the ship BUT i am certain they were first used to launch the V1 rockets (doodlebugs)during WW2. --Kkishappy@btinternet.com 18:38, 5 July 2006 (UTC)tina

Have you checked our article on steam catapults? Our article on the V-1 flying bomb doesn't specifically mention the technology used by the launch ramp, but it appears to predate the development of the modern steam catapult. — Lomn | Talk 19:38, 5 July 2006 (UTC)

[edit] Technical Term for Nasally Voice?

Is there a technical and/or medical term for a nasally or congested sounding voice (ie Billy Joe Armstrong's voice)? HamillianActor 18:45, 5 July 2006 (UTC)

I've heard it called Adenoidal.--Anchoress 18:48, 5 July 2006 (UTC)
The sounds in language produced nasally are called Nasal consonants -Obli (Talk)? 18:49, 5 July 2006 (UTC)
Vowels can be nasalized and become nasal vowels. Just listen to a French person saying enfant or compare the pronunciation of "tackle" and "mangle" carefully. --Kjoonlee 17:11, 6 July 2006 (UTC)

The technical term is actually "denasalized speech", which you can quickly prove by blocking air and sound flow from your nose with your fingers. Congestion or large adenoids do the same thing. alteripse 01:28, 7 July 2006 (UTC)

[edit] Need sources for Battery electric vehicle

Greetings, esteemed reference desk helpers!

Editors on Battery electric vehicle are trying to get it in shape for Featured Article status by June 21st when the Who Killed the Electric Car? movie opens. We have two pesky {{citation needed}}s which I hope you can help resolve:

  • (A) Are there any known instances of people replacing batteries in an electric vehicle as an alternative to recharging? Are there any "automatic" (robotic?) systems which do this?
  • (B) Is there a source for the statement that the "greater cost of lithium and zinc air batteries has discouraged their use in commercial vehicles"?

Thanks for the extra eyes on this. AnAccount2 19:42, 5 July 2006 (UTC)

It sounds like A is gonna be a doozy. I'll check through some catalogs when I get home tonight to try to get some commercial costs for B - you may find [10] or Newark Electronics as a starting place to look for industrial battery prices (I don't know if they sell electric-car batteries but they sell nearly everything else!) Nimur 21:04, 5 July 2006 (UTC)
I sure wouldn't be swapping the batteries in current mass-produced electric vehicles. I'm sure there's one or two somewhere that have batteries a normal human could lift. The common cars have batteries that would require an industrial robot to remove and replace on a regular basis. For reference, the battery backup for my computer weighs over 100 pounds and would barely get a car rolling, let alone run it at 55mph for at least 3 hours. The better viable option would be a removable trunk. You back into an open slot on a charger and remove the trunk. Then, using some batter that doesn't remove, pull forward and back onto the charged up spare trunk. --Kainaw (talk) 00:16, 6 July 2006 (UTC)

[edit] Safety of the Space Shuttle

Ever since the Columbia accident, both Space Shuttle missions since (STS-114 and STS-121) have been dogged by problems with the foam insulation. But it seems to me that these problems only show up because they're looking for them: in other words, problems were had with foam insulation before Columbia, they just weren't looked for. Is it a case of problems with foam have been there all along and were only noticed after the Columbia accident, or is it actually a problem that's only recently appeared and happens very rarely, hence the delays experienced in the last two missions (because there is a high probability that these events are fatal, as opposed to a common event which sometimes causes problems)? Thanks, sorry that my question is a bit rambling. Sum0 21:34, 5 July 2006 (UTC)

It's a long-term deal that's only recently become a concern (due to the loss of Columbia). Similarly, tiles from the underside of the shuttle are missing after every re-entry. It's expected behavior and no big deal currently, but you can bet that if a shuttle were lost due to previously-normal tile loss (and if the program weren't then immediately cancelled), the tile issue would move to the forefront much as tank foam has. — Lomn | Talk 21:58, 5 July 2006 (UTC)
The problem was only made prominent by the loss of Columbia. I believe. --Proficient 09:32, 6 July 2006 (UTC)
I heard on the tv (on the FOX news to be precise) that peices of foam will fall off during every lift-off and that there was no way to prevent that from happening. Atleast thats what I think he said. Can anyone confirm that? Jayant,17 Years, India • contribs 13:24, 6 July 2006 (UTC)
I don't have a link, but yes, that's correct. What NASA has been spending so much time on is preventing the foam from falling off in pieces large enough to do damage. As I understand it, the pre-launch cracks in foam are a concern because (warning: invented numbers ahead) a 10 cm crack might let a damaging 10 cm chunk of foam fall off when normal non-damaging foam pieces are no bigger than 5 cm. — Lomn | Talk 16:23, 6 July 2006 (UTC)
If you check out the official report (11M PDF) on page 127, you'll see a chart of all of the "lower surface damage" events during all of the Shuttle flights. It also indicates the flights that had foam come off of the bipod ramp (the source of the fatal foam on the Columbia). Seven times, including STS-107. In fact, all of Chapter 6 is pretty enlightening when it comes to chronic Shuttle launch problems. -- Plutor 17:00, 7 July 2006 (UTC)

[edit] Evolution of the horse

I've always wondered why horses have hooves instead of toes and how they evolved? This image is really helpful, it shows me how the foot began with five toes, then the other four toes kind of disappeared overtime. I was pretty sure that in evolution, things don't just disappear (or do they?). My question is, shouldn't modern horses' feet still have remnants of those other four toes? Maybe they're in the form of small bones in the leg, or maybe cartilage? --Jonathan talk 22:29, 5 July 2006 (UTC)

You are correct. Things rarely just "disappear" in evolution, and some horses will (very rarely) have three toes. One main hoof, and two smaller ones. I think. I'm sure I read that somewhere. Humans, likewise, have hands adapted from fins which have a lot more than 5 "fingers", and polydactyly at birth is quite common in humans (1 in 400 i think?)
Actually, the number of digits in the tetrapod limb stabilized at five shortly after the first tetrapods evolved. Polydactyly involving more than five digits almost always involves a "repeat" thrown in. That is, one of the five ancestral digits was accidentally repeated. This is different from the case of three toed horses, in which presumably the suppression of two of the ancestral digits failed. --Ginkgo100 talk · contribs 01:11, 6 July 2006 (UTC)
It's mentioned at Evolution of the horse#Toes, for one. EdC 23:51, 5 July 2006 (UTC)
They dont dissapear often, my biology textbook (which I've now handed back) had diagrams which showed that just about all vertabrated have the same arm/fore-leg/wing bones, just in different places, and occasionally different structures, things were through evolution elongated, shifted about, shortened, re-shapen, and all manner of things, but ususally the same bones were there. Philc TECI 00:33, 6 July 2006 (UTC)

Thanks for all the answers, you answered my question. I took a closer look at this image and apparently the other four digits have shifted upwards and become these tiny bones at the top of the foot. Thanks for all the answers, though! I thought the polydactyly article was interesing. --Jonathan talk 03:20, 6 July 2006 (UTC)

Interestinh how in the skeletal structure it shows the evolution of feet to hooves, yet, in the diagrams, they all clearly have hooves. Philc TECI 21:32, 6 July 2006 (UTC)
That's because they're horses. Horses have hooves. --mboverload@ 22:00, 6 July 2006 (UTC)
Maybe you should atleast have a look at the picture before making an ass out of yourself. The picture shows the evolution of horses from having feet to having hooves. Yet all the diagrams, including those of the diagrams of the ancient horses that have feet, have hooves. Philc TECI 20:36, 7 July 2006 (UTC)
Ah, Philc, amiable as ever. Black Carrot 18:11, 9 July 2006 (UTC)
They have hooves, but still have more than one toe. I assume it would be like tapirs "All tapirs have oval, white-tipped ears, rounded, protruding rear ends with stubby tails, and splayed, hoofed toes, with four toes on the front feet and three on the hind feet, which help them walk on muddy and soft ground." Skittle 19:05, 9 July 2006 (UTC)

[edit] Colostrum Production

I am wondering if colostrum is ONLY produced during pregnancy? Can your body produce Colostrum when you're not pregnant? If you have previously given birth,(over 18months) can you still have the production of Colostrum?

Deidre--209.172.121.91 23:00, 5 July 2006 (UTC)

  • I'm pretty sure it is only produced during pregnancy. I suspect you could stimulate colostrum production with the right hormone mixture but I don't know if that has happened or not. I have never read anything which indicated that colostrum was a one-time deal; if you have multiple births, you can probably have multiple instances of colostrum production. --Fastfission 23:14, 5 July 2006 (UTC)
  • Hmm. I wonder if some forms of the pill can cause this: it is supposed to simulate pregnancy to fool the menstrual cycle - it's feasible at least that this could be a side-effect of it. Grutness...wha? 03:28, 7 July 2006 (UTC)