Wikipedia:Reference desk archive/Science/2006 June 17

From Wikipedia, the free encyclopedia

You have new messages (last change).
Humanities Science Mathematics Computing/IT Language Miscellaneous Archives
The page you are currently viewing is an archive page. While you can leave answers for any questions shown below, please ask new questions at one of the pages linked to above.

< June 16 Science desk archive June 18 >


Contents

[edit] Cancer Rates

I was wondering why it is that the rate of cancer in our society today seems much higher than it was in years and centuries past. So this is a two part question: is this really true and why is this the case? I realize that this is a complicated question with no simple answer, but I was wondering if someone could explain it just a little. Thanks! Andromeda321 00:05, 17 June 2006 (UTC)

  1. Because people live long enough to get it rather than dying of other causes.
  2. Because we can now diagnose it readily. --Robert Merkel 00:17, 17 June 2006 (UTC)
Agreed. Since 100% of people still die, and far fewer die of some things, like bubonic plague, that means far more people must die of other things, like cancer, to keep the death rate at 100%. (If we ever fall short of the 100% death rate, then people will start living forever, and we can't have that, now can we ?) StuRat 01:35, 17 June 2006 (UTC)
Others claim that cancer rates have increased due to an increase in carcinogens in our evermore polluted environment and modern lifestyle. Melanoma, for example, is thought to be on the increase, possibly because high risk individuals become exposed to more UV at a younger age. This may be due to a combination of factors: an increase in intercontinental travel (childhood holidays to hot climates), because northern Europeans have colonised hot countries over the last few centuries, the fact that suntans have only become fashionable over the last 50 years and that UV exposure levels may be increasing due to ozone depletion. Then there are the hundreds of thousands (or perhaps millions) of past and future cancers that may or may not have been caused in part by radiation exposure after Nagasaki, Hiroshima and Chernobyl. Rockpocket 07:56, 17 June 2006 (UTC)
Chernobyl is probably still significant statistically in Eastern Europe (where entire countries were exposed), Hiroshima and Nagasaki, probably not. There are more people killed by lung cancer alone in the United States per year that died as a result of the bombing. (As for its contribution to worldwide fallout levels, anything it would have added was no doubt overshadowed by the decades of atmospheric nuclear testing which followed). --Fastfission 15:46, 17 June 2006 (UTC)
Many types of cancers are also lifestyle diseases, and you'd probably want to know trends of known carcinogens consumption as well (i.e. cigarette smoking, which can take decades to develop into cancer). I'm also guessing that there are other man-made issues such as coal pollution that come into play. Cancer is a complicated disease and its causal mechanisms are still being studied; additionally there are statistical questions (as noted above) which come into play, and it doesn't help that almost every cause has some sort of political aspect to it (making them endlessly disputed). --Fastfission 15:46, 17 June 2006 (UTC)

[edit] Is it possible to pull your own head off?

This may be the stupidest question of the day, but is it humanly possible to rip off one's own head? If I were sufficiently strong and motivated, by insanity, PCP, or boredom, would it be possible to decapitate oneself by pulling? I know for a fact that people's limbs have been pulled off by machinery. Follow-up question: would it be possible to sever one's own head with a hand-held knife, e.g. a machete? Don't ask me why these things are on my mind. Bhumiya (said/done) 00:20, 17 June 2006 (UTC)

I think both of those things are physiologically impossible, because even if you have strong mental motivation, the pain is so intense that your reflexes take over and prevent you from continuing. That's why people have to literally "fall" on their swords to commit suicide, because their reflexes prevent them from simply stabbing themselves. —Keenan Pepper 00:28, 17 June 2006 (UTC)
You don't have to fall on your sword. People are perfectly capable of stabbing themselves to death (hara-kiri, for example, or even just wrist-slitting with subsequent bleeding). Cutting off a limb is also possible. Ripping off might be another matter, and the head would be yet more difficult as you would be unable to move your arms after the spinal cord was severed, rendering that feat, I think, pretty much impossible. - Nunh-huh 02:29, 17 June 2006 (UTC)
I wonder what the force required to pull a head from a body is? --jpgordon∇∆∇∆ 02:36, 17 June 2006 (UTC)
It's big. The "Myth Busters" did a segment in which they explored the possibilty of decapitation by ceiling fan, and discovered it took a lot of force to sever a head - more than they were able to develop. Obviously it would be a great deal more to pull it off by blunt force. - Nunh-huh 02:39, 17 June 2006 (UTC)
Did they test that on a real person? Mr. Lefty Talk to me! 02:43, 17 June 2006 (UTC)
No, that would have been difficult to budget for. They used a few person-standins. Ah, here's the synopsis. - Nunh-huh 03:04, 17 June 2006 (UTC)
I imagine, and this is just speculation, that if PCP were to remove all pain and/or care about pain, then one might be able to pull one's head so hard as to sever the spinal cord, at which point it would be impossible to continue to pull one's head the rest of the way off. --Ginkgo100 talk · contribs 04:00, 17 June 2006 (UTC)
I think that sounds reasonable, but then again, PCP addicts have done some pretty astonishing things to themselves. I remember reading about someone who peeled his face off with a broken mirror. Of course, this is different. I think if I were an abnormally strong individual with no sense of pain and a desperate, irresistible urge to decapitate myself, it might almost be possible, if I began by tearing up my neck and then snapped the spine with a single forceful jerk before I had the chance to bleed to death. The harder I think about it, the less plausible it sounds. Still, it might make for an interesting episode of CSI. Bhumiya (said/done) 05:39, 17 June 2006 (UTC)
Both this chap and this chap seem to have enough will power to cut off parts of themselves. Cutting of your own head would be a bit harder, due to the fact that you would lose conciousness pretty quickly if you didn't manage it on the first attempt and that its hard to think of a good reason for doing it to focus your mind. But that aside, i bet it would be possible with a long enough and sharp enough blade and enough power in your arms to generate the force required. I bet some of those samurai dudes could do it. Rockpocket 07:42, 17 June 2006 (UTC)
I think it would be extremely unlikely for it to happen, unless perhaps you had some kind of defect that made you have weak neck bones that would allow for the possibilty to pull off your head. A possible scenario would be this: Your head was "loose" to begin with (meaning you had some kind of bone disease or other ailment) plus you had strong arms, which would be unlikely considering how close the neck/head is to the shoulders. I wonder if anyone has actually pulled off their head out of the billions of masses. --Proficient 16:06, 17 June 2006 (UTC)
Maybe not, but a lot of people over the years have been told to pull their head in. A terribly rude injunction, I've always thought. There are so many more pleasant ways of telling a person their existence is no longer required. (lol) JackofOz 00:54, 18 June 2006 (UTC)
I don't think it's easy even to pull someone else's head off without some applience (though it'd be dangerous to try because you can get one's spine hurt seriously). As for cutting one's own head off, I think it's possible with a guillotine or some similar device. It might also be possible by lying on the rail and waiting for the train, but I don't know if that can be done so that it would reliably cut your head off on the first attempt. I don't know if it's possible with a sword, but I think only someone proficent in using the sword have a chance doing that. In any of these cases, it's ver likely to wound yourself heavily, even fatally, even if you don't succeed. So don't try this at home. – b_jonas 12:00, 23 June 2006 (UTC)

[edit] Help

Hello, I’m hoping you could provide me with some help. I have a physics final on Monday, and we got a review package that resembles nothing of the kind of stuff we’ve done in class. I hope these aren’t too many, here goes:

When a certain rubber band is distance x, it exerts a restoring force F = ax²-bx, where a and b are constants. The energy stored in the rubber band when stretched from x = 0 to x = L is:

a) 2aL –b

b) 2aL+2b

c) aL^3/3 + 2bL

d) -aL^3/3 + bL²/2

e) aL^/3 + bL/2

The correct answer is d. I have no idea how to get that, and the only reason I think it might be d is because it has a negative in front of the a because the Force is opposite the x

The next question: A 1kg mass moves in a straight line under the influence of a force. The potential energy is given by U(x) = 6x²-2x^3 where U is in joules and x is in meters. If the mass has a speed of 2m/sec when it is at x = 1 meter, its speed when it is at x = 0 is:

a) 0

b) 2 √2 m/sec

c) 3√2 m/sec

d) 2√3 m/sec

e) 2√6 m/sec

The answer is d. I am confused with this problem because it says “ mass moves in a straight line”, and then it mentions potential energy, which must be 0 because the object has no height. Extremely confused with this one, I think the formula might just be a trick and not actually be useful, but I have no idea. Afterwards in the next question, it asks for the acceleration (which turns out to be -6). If I knew how to do the above question I might be able to do the one after it, but I’m unsure and just completely lost. Any response would be very appreciated. – Hopelessly Screwed

I don't think we're supposed to answer homework problems, but too bad.
For question 1: When you stretch the rubber band, you're doing work on it against the restoring force of the rubber band. The key is that work (which is a form of energy) is given by \int F dl. That is, the work done is the integral of the force exerted along a path (a negative sign is needed if "F" is the restoring force instead of the force exerted). In this case, the expression for the work is W = \int^L_0 (- a x^{2} + b x) dx (note that the signs are reversed because the work you do to stretch the band is the opposite of the restoring force). Hopefully you can integrate that to obtain W = - \frac{a L^{3}}{3} + \frac {b L^{2}}{2}
As for question 2, what they mean by "the mass travels in a straight line" is that it is restricted to the x dimension; i.e. there are no other dimensions in which to move. The problem is asking you to consider an arbitrary potential energy, not necessarily the potential energy due to gravity, so "height" is not an issue. For instance, this could be the potential energy of a spring that a mass is pushing against.
The key to this problem is conservation of energy. No matter where the mass goes, it's mechanical energy (potential energy + kinetic energy) will not change, (assuming no non-conservative forces like friction). Therefore, if you can figure out its total mechanical energy at some time, it will be the same at all other times. In this case, the potential energy depends only on position; you are given the expression U(x) = 6x2 − 2x3, and kinetic energy is given (as always) by K(v) = \frac{m v^{2}}{2}.
At some time, the problem says the mass has velocity 2 m/s, so it's kinetic energy is (1 kg * (2 m/s)^2)/2 which comes out to 2 Joules. At that time, it is at x = 1 m, so its potential energy is 6 * (1^2) - 2 * (1^3), which comes out to 4 Joules. Therefore, at all times (unless some outside force acts on it), its mechanical energy will be 6 Joules. When x = 0, the potential energy of the mass is 0 (zero), so the kinetic energy must be 6 - 0 = 6 Joules. Now, you can use the kinetic energy formula in reverse to figure out the velocity. v = \sqrt{\frac{2 K(v)}{m}} This gives sqrt(2 * 6 Joules / 1 kg) = sqrt(12) = 2 \sqrt{3}.
By the way, a hint for finding the acceleration at x = 0: Since W = - \int F dx, F = - \frac{dW}{dx} and always remember that F = ma where "a" is acceleration.
Hope that helps - good luck.--Bmk 05:19, 17 June 2006 (UTC)
In the first question, force F(x) is dependent on x. Differential work done when stretching the rubber band by a length of dx is F(x)dx. Work done in stretching rubber band from x = 0 to x = L is \int_{0}^{L}F(x)dx.
In the second question, it is not stated whether the force is position-indepdent (i.e. indepdent of x). To get an answer, some assumption is needed. Perhaps the unstated assumption is that the force is constant. With that assumption, you can calculate the work done, and therefore the increase in total energy in moving the mass from x = 0 to x = 1. The total energy of the mass at position x is the sum of its kinetic energy (related to its speed) and its potential energy (given by the formula for U(x)) at that position. Given the boundary conditions, you can work out its initial kinetic energy (and therefore speed) at x = 0.--72.78.101.61 05:11, 17 June 2006 (UTC)
It just occurred to me that in my interpretation of the second question (i.e. the "force" is external and not accounted for by U(x)), the question does not provide enough information to allow an answer to be calculated. Maybe Bmk's interpretation is the intended one.--72.78.101.61 05:43, 17 June 2006 (UTC)

"We haven't done calculus yet so I'm unfamiliar with integrals. Is there any other way? Thanks for helping!"

Sorry - calculus is the only way to go for a non-linear force like these. --Bmk 05:26, 17 June 2006 (UTC)

[edit] Orange peelings and antibacterial benefits

Not sure where I heard this, but I heard that orange peelings can be used to cultivate antibacterial agents such as penicillin. Am I completely wrong about this, or is there some truth to it?--24.231.16.109 04:40, 17 June 2006 (UTC)

Penicillium mold grows easily on orange peel. Just leave some oranges in a drawer or even your refrigerator too long and you will proabably be rewarded. Extracting the penicillin will be your challenge and you may want to make arrangements with your local pharmaceutical company to use their purificaction and testing facilities over a weekend, if you don't have a sterile separation and analytical lab in your basement. Next you will want to borrow some culture petri dishes and bacterial cultures in the microbiology lab of your local hospital to prove the stuff works. Good luck. alteripse 11:15, 17 June 2006 (UTC) PS: Keep in mind of course that penicillin costs maybe 10 cents a tablet.

[edit] Optics glossy/matte colours

OK, I want to explore different colours and how you can make them different. One aspect is the colour itself. Anoter aspect is the gloss, whether the colour is shiny or matte. What other optical aspects can affect the way a colour or surface visually appears? I guess there's also infrared. Can some animals see infrared surfaces? If a surface was truly infrared, what colour would a human see it as?--Sonjaaa 06:24, 17 June 2006 (UTC)

Translucency springs to mind. And yes, some creatures (such as certain species of insect) are capable of seeing infra-red. Provided all non-infrared light was absorbed, a human would see such a surface as black GeeJo (t)⁄(c) • 07:30, 17 June 2006 (UTC)
You may also want to consult gloss (material appearance). --Michel M Verstraete 23:12, 19 June 2006 (UTC)

[edit] Alcohols and Sodium Metal

Why is it that primary alcohols react more vigourously with sodium metal than secondary and tertiary alcohols? 138.130.252.56 09:57, 17 June 2006 (UTC)

The alkyl groups are electron-donating and thus strengthen the O-H bond in the alcohol. This makes the alcohol a weaker acid and less likely to lose a proton to be reduced by the sodium metal. The more alkyl groups present, the more electrons get pushed into the O-H bond. G N Frykman 17:30, 17 June 2006 (UTC)

[edit] software testing

Hi, i would like to know about the most used software testng tools and why the thes tools are used ?? I would also like to know about the comparitive advantage with other tools Regards Tommy

Tommy, I think you need to make your question a lot more specific to get a useful answer. What kind of software are you referring to? What OS? From what point of view (data integrity, user friendliness, vulnerability to malicious attacks, etc). --vibo56 talk 19:23, 17 June 2006 (UTC)
Some of the external links in our Software_testing article may help. -- Avenue 00:46, 20 June 2006 (UTC)
The best answers may be broad categories:

Many of these are packaged into an Integrated Development Environment (IDE). More specifics would be needed to give better answers. Nimur 17:13, 22 June 2006 (UTC)

this question is helpful for me...coz i m facing a problem that when i start my computer its bios start working but suddenly stuck!!!!...i wait for many minutes but vain....i restart it then bios run but.. when windows start it simultaneously says "saving your settings",... n again shut down..plz help me out.


[edit] Bios Virus

hi my old laptop has not worked for a month for so now its a bit expencive to get fiexd, so i lent it to a friend who sead they would look at it. they say it has a bios virus, i was wondering what a bios virus is?

That would be a Computer virus which has somehow affected your computer's Basic Input Output System. The BIOS is a small program that tells your computer how to startup. Although BIOS viruses are said to be rare, once your BIOS has been corrupted, there is not much that can be done. The term itself is a little misleading, as the virus does not "live" in the BIOS and can not replicate itself from there. But if your computer has been affected, the terminology is the least of your worries. --LarryMac 20:33, 13 June 2006 (UTC)
Resetting the CMOS just might work. Not sure, though. -- Миборовский 05:53, 14 June 2006 (UTC)
How do you reset the CMOS? --Silex 21:02, 14 June 2006 (UTC)
Laptops are tough. CMOS is located on your motherboard so you either have to open it up to expose the motherboard (NOT recommended) or ask your Dell/IBM/HP guy. -- Миборовский 22:27, 14 June 2006 (UTC)
Well where does the BIOS virus reside if it does not 'live' in the BIOS? And would 'flashing the CMOS' work? To do that, do I have to jump some pins or something? --217.44.0.212 10:56, 17 June 2006 (UTC)
Maybe a BIOS update will correct your problem by overriding the defect. What is the exact problem with your comptuer when you say that it's not working? Is the operating system not functioning, the computer not turning on at all, or something else?--Proficient 11:17, 17 June 2006 (UTC)
To clarify, a BIOS virus should be removable by flashing (not possible if you're already at newest version, though) or by resetting CMOS by removing the battery (CMOS battery, not laptop battery) for a few minutes. It can also generally be done by changing a jumper connection. But either of those ways requires touching the motherboard - not easy on a laptop. -Goldom (t) (Review) 11:44, 17 June 2006 (UTC)
Reccommended procedure:
  1. Verify the claim that there is a problem with the bios. To do this, you might check if the laptop boots normally with a bootable CD such as knoppix. If this is successful, the problem is probably not with the bios.
  2. If you want to restore bios factory defaults, you can normally do this from within the menus of the bios setup program. If you pay close attention while the pc starts its boot sequence, you will see a message which tells you how to open the setup program (it might be, for example, holding down the F2 key when the pc starts). A text mode setup program will open, with a menu. Somewhere, usually on the "Exit" menu, there is an option "Load Setup Defaults". If you are certain that the bios is messed up, this should restore it. You also need to "Save changes" before exiting. --vibo56 talk 13:35, 17 June 2006 (UTC)

[edit] Schrodingers Equation

Ok i know the what the equation looks like but how do you solve it for a given particle of some mass whose energy contribution is V(x,y,z)using the equation. could you show it using an example. how do you solve the hamiltonian? --Debanjum 11:59, 17 June 2006 (UTC)durin

could you be more specific - when you say the energy contribution is v(x,y,z) do you mean that its energy is a function of its position in 3 dimensional space? What do you want to do? find the wavefunction that satifies certain conditions or what?HappyVR 15:16, 17 June 2006 (UTC)
See Category:Quantum models for some examples. Conscious 05:11, 18 June 2006 (UTC)
Oops sorry, somehow I sort of misread your question - the equation is a partial differential equation - check that page for methods of solving equations of that type.HappyVR 15:41, 24 June 2006 (UTC)

[edit] How hard would it be to write this software?

Here's something which has been on my wish-list for awhile. I'm wondering how difficult it would be to pull off.

Basically, the program would be a web browser which could simulate a locally hosted Apache server. Why do it? Because then you could write applications in server-side languages like PHP and distribute them to people easily. No need to install a whole Apache server on their machine if it is just going to be run locally. If you could combine PHP, Apache, etc. into a browser-like application itself, then you could easily distribute PHP files to people and not have to worry about all of the idiosyncracies of actually installing a server.

Does that make sense, conceptually? I want a way to easily distribute PHP programs which are made to be run off of the local machine (and not as true web applications), but the only way to currently do that is to install Apache and PHP (not simple operations, and overkill). It seems like it shouldn't be impossible to have a browser-like-application which could itself replicate the behavior of a local server.

Possible? Impossible? Hard? Easy? Already done? Any thoughts would be appreciated. --Fastfission 16:00, 17 June 2006 (UTC)

I'm not aware of any such beast. If you want to avoid installing PHP, you would either have to integrate the PHP interpreter source code into your browser code, or write your own PHP interpreter. The former is not tempting to me from a maintenance point of view, and the latter is reinventing the wheel. I'd say both sound like a lot of work. But I agree, it would be nice if the user could just download the PHP+ServerEmulator plugin, and be ready to use your PHP program. --vibo56 talk 19:40, 17 June 2006 (UTC)
What I was hoping one could do is just integrate Apache into the browser and then integrate PHP into that. I don't know how much re-inventing you'd have to do — all of the code for PHP, Apache, Firefox, etc. is open source.. it's just a matter of fitting it all together neatly, I suppose. Which is probably hard. :-) --Fastfission 05:20, 18 June 2006 (UTC)
One approach might be to write a user-friendly installer that installs a browser, web server and PHP interpreter at the same time. Getting it right is not easy, however. A similar thing has been done for the windows version of LyX, but I have not been able to get the installation to work properly on my system (now trying again, uninstalling everything, reinstalling each package separately). --vibo56 talk 08:45, 18 June 2006 (UTC)
A best compromise is to use Client side scripts such as Javascript. This will entail sending them a script or HTML document. If you're familiar with PHP, Javascript should be very similar. Nimur 17:17, 22 June 2006 (UTC)

[edit] Biological classification systems

I was wondering - regarding the classification system of plants and animals: Is there an official board or similar organisation that decides when a new classification is valid. Some of the reclassifications I've seen seem to be based on published papers - which makes sense since these things are peer reviewed - but surely getting a paper published is not all that it takes - maybe some sort of consensus rules here, I've honestly no idea how it works in practice - I assume differences of opinion do arise - how are these sorted out? Are disagreements amongst biologists worked out in a similar to conflicts on wikipedia?HappyVR 16:09, 17 June 2006 (UTC)

I look forward to an answer to this question, but I sure hope that no one in the real world resolves conflicts like we do! Melchoir 18:51, 17 June 2006 (UTC)

The International Commission on Zoological Nomenclature and International Association for Plant Taxonomy approve names proposed by the discovering scientists. Rockpocket 19:34, 17 June 2006 (UTC)
Thanks, but I'm not sure if this was the answer I was looking for - the links you provide guides to the nomenclature of species, but I was thinking in terms of when a conflict occurs regarding the placement of a given species within one or another genus - ie issues of taxonomy not naming - can anyone help?HappyVR 19:47, 17 June 2006 (UTC)
I'm sorry, i misunderstood your question. This article seems to suggest the peer reviewed publication process is how one establishes new taxonomy. One assumes, like the scientific process in most disciplines, time determines whether the community will accept the proposal, based upon further work supporting or refuting the evidence. Like everything in science, there is often no "right" answer, it comes down to who has the most convincing argument.the answer to this posting would seem to support this. Rockpocket 00:14, 18 June 2006 (UTC)
Thanks, that pretty much answers it. I was wondering if there was an organisation that 'rubber stamps' these things such as the Linnean society or 'international body of biological scientists' - I don't suppose 'rubber stamps' are in keeping with the scientific ethic though.HappyVR 00:58, 18 June 2006 (UTC)
Taxonomy is a science and it is normal to have dissensions with new theories. The dispute between traditional taxonomy and cladistics is beginning old and is still sometimes in the focus of science media. What are the criteria to sort life forms : form itself, bones, tiny characteristics, genes ? This also a question of fashions, which must evolve. --DLL 20:29, 17 June 2006 (UTC)
See International Code of Botanical Nomenclature for the WikiPedia article relating to plant taxononmy. For botany, the fights seem to be fought at the congresses where the code is decided (next one due this year?). An interesting story giving some insight into the process is: The name Acacia retained for Australian species. As far as zoological toxonomy is concerned, the situation seems to be less formal, confirming what Rockpocket said. Butler says the following in his article on the issue of Pituophis Taxonomy (I quote the whole paragraph to make the context clear, the editor's note is the pertinent bit): "Before we discuss Pituophis, I first must describe the formal and informal processes of taxonomy. Formally, there are two groups that make decisions on the names of species; the American Association of Zoological Nomenclature, which is a satellite-organization for the International Commission on Zoological Nomenclature (ICZN). Generally, if there is a published dispute regarding the name of a species, the authors will present their case to the ICZN, and they will make a ruling based on their established code. However, more typically and informally, once a name sticks, and is used frequently, then the ICZN rarely gets involved. (Ed. Note: The ICZN judges on procedures and does not get involved with species validity - that is the purview of peer reviewed journals.)" So "peer reviewed journals" seems to be the case for zoology. --Seejyb 11:04, 18 June 2006 (UTC)

The various naming committees (ICZN, ICBN etc) adjudicate a very narrowly defined set of issues to do with biological names and biological types. So questions like, "what is the type specimen for the species Homo sapiens?" or "is the name Archaeoraptor available (in the technical sense of 'available')?" are appropriate for the committees. But questions about actual relationships, like "how many genera of gibbons are there?" are outside the scope of the committees and must be settled by research, peer review, and debate. Gdr 11:19, 19 June 2006 (UTC)

[edit] Sinking lifejackets?

I have heard an urban legend that the "old" lifejackets made of cork or kapok used to lose buoyancy after being immersed in water for a long (many hours) period of time? Can anyone confirm or deny this? Thank you for time. Mieciu K 14:08, 15 June 2006 (UTC)

A styrofoam one would be better... Would you like a lifejacket like this; it's incredibly light.
Kilo-Lima|(talk) 17:18, 17 June 2006 (UTC)
But I'm interested in lifejackets that sink. I have heared sinking lfejackets caused deaths during the USS Indianapolis (CA-35) dissater, and others but I'm unable to confirm it. Mieciu K 21:17, 17 June 2006 (UTC)
According to this NOVA transcript, early cork lifejackets had many problems: "The buoyancy is equally distributed around the body, around the front of the body and around the back of the body. So, if the person was unconscious and was lying face down on the water, he would remain stable in that position. Secondly, there was no support for the head or neck. It's really just wrapped around the top of the body, leaving the shoulders and head out of the water. And that's fine for somebody who is conscious, who is alert, who is able to hold his head out. But the head actually is very heavy, the specific gravity of the head. When a person loses consciousness, the neck muscles are failing, and then the head tends to flop forward, and they could be found floating face down in the water, inhaling the water." However, I can find no reports of cork or kapok lifejackets actually breaking down and losing their buoyancy. I would expect that cork would be fairly resilient. Consider how long corks survive in bottles of wine without breaking down. Then again, cold water might have a different effect. Also, any lifejacket, even one made from synthetic fibers, can break down if it develops a tear or becomes infested with mold, mildew, etc. I think the Indianapolis survivors may have had problems remaining upright. Their unbalanced lifejackets would have required them to constantly maintain their balance in the water. If you lost consciousness or became too tired, it would be easy to turn over in the water and drown. But I can find no evidence that life jackets actually sunk. Bhumiya (said/done) 01:36, 18 June 2006 (UTC)

[edit] IIS

I might be migrating from Apache to IIS sometime soon (and hence PHP -> ASP.NET). Here are a few questions...

  • Is there an ASP.NET interfact for PhpBB? I have a lot of mods and I don't want to have to migrate my phpBB installation into another app.
  • Is there a system similar to Cutenews for ASP.NET that is free? All I want is to be able to post news that is integrated into my frontpage. I'm able to design the rest.
  • Is Web.config analogous to .htaccess? If not, is there a directory-level configuration file? Becuase I need to be able to define custom 404, etc. files as well as disable directory listings for certain folders, etc. And I share hosting with my dad, so I'm a subdirectory of his site.
  • Is there anything else I should know?

I'll be on another host so it won't be my server. — Ilyanep (Talk) 17:04, 17 June 2006 (UTC)

ASP.NET and PHP are two entirely different programming languages. phpBB and any mods you have for it will only run under a PHP interpreter. However, it is certainly possible to run PHP scripts under IIS [1], just like it's possible to run ASP.NET code under Apache [2]. So, you can either contact your hosting provider and see if they support PHP, or move to a different forum package written in .NET. (here are some possibilities)
If you can't use PHP and are looking for a Cutenews substitute, you might want to check Category:Content management systems.
From browsing Google for information about Web.config, it does seem to serve roughly the same purpose as .htaccess. However, I'm not all that familiar with ASP.NET myself, so you'll have to ask somebody else if you have any detailed questions about it.
Anyway, hope this helps! —David Wahler (talk) 18:15, 17 June 2006 (UTC)
web.config is kind of the same as .htaccess, in that you can define application settings, including 404s (for .net processed files only, for example .aspx, but *not* for .html, because that's served up by IIS directly). Directory listings are, again, controlled by IIS, not asp.net. Once IIS7 comes out then web.config will run the whole show. Whilst I don't know of a direct cutenews replacement [DasBlog] is a .net blogging engine that uses the file system, not a database. I guess it depends what bits of cutenews you want replicated. --Blowdart 23:36, 17 June 2006 (UTC)
Just something that can display news on the front page using a design template that I give it. And then I can do something like I do include(...); in PHP — Ilyanep (Talk) 03:51, 18 June 2006 (UTC)
I've not seen something like that. And include isn't part of asp.net, you would have to embedded it as a custom control. It doesn't look hard to code, so I'm sure there must be something out there. --Blowdart 15:44, 18 June 2006 (UTC)
Well, I understand there'll be some differences between PHP and ASP.NET, but I just don't want to have to get a package that essentially codes a whole website for me. — Ilyanep (Talk) 16:50, 18 June 2006 (UTC)

[edit] Use of cows milk vs. soya milk and toothpaste

Gillian McKeith states that cows milk is bad, and that you should only drink soya milk (which I have now been doing). She states that it forms some sort of mucus on the stomach lining and that is only for use on a calf (the milk). Is she right? Also, I have begun using normal toothpaste with whitening toothpaste, using the the normal first then the whitening. Will the two toothpastes cancel each other out? Thanks, Kilo-Lima|(talk) 17:24, 17 June 2006 (UTC)

Whether cow's milk is "bad" you might like to consider that generations of people in many (though not all) cultures have been doing it for a very long time, and that our current expectations of longevity and health are mainly concerned with people who have been drinking it at some time. You might like to consider what actual or potential problems cow's milk is claimed to cause, and consider whether there is any evidence that this is in fact the case, perhaps by comparison with other cultures who don't drink cow's milk. I have never heard of this person, but I would also check for a secondary agenda, for example whether she is also an advocate of animal rights, who might consider it desirable to reduce the many animal deaths caused by drinking cow's milk, and if so, whether you share that agenda.
Some of the racial groups who have not been drinking cows milk for a long time (see Lactose_intolerance#Biology). Obviously if you are lactose intolerant then cows milk will be bad for you. -- Chris Q 09:24, 19 June 2006 (UTC)

For the second question, what do you mean by "cancel out"? Your teeth won't become dirty again, increasing tooth decay. Notinasnaid 17:51, 17 June 2006 (UTC)

If anything, using two toothpastes will only help. I don't see what's wrong with doing a double whitening though. ;o --Proficient 19:56, 17 June 2006 (UTC)
I'd be more worried about trusting someone who can only call herself a Doctor because of a "mail order" PHD from a non-accredited university (The American College of Nutrition). Please, consider your source. --Blowdart 20:15, 17 June 2006 (UTC)
Humph, that source does not know the difference between the UK and England, especially when Gillian McKeith is Scottish. Kilo-Lima|(talk) 20:49, 17 June 2006 (UTC)
Are you complaining about the "London, England" bit on that page, because that's the only part I could see that you could make that comment about; and it is, obviously, accurate. --Blowdart 23:37, 17 June 2006 (UTC)
Ms McKeith is likely referring to rennet, since there is nothing else resembling her fanciful notion of a milk-specific "mucous lining" in calves. Soy milk as you buy it is a highly modified synthetic product. The rate of allergy is 5 to 20% (see [3]) and there is about a 50% cross-allergy with cows' milk. For young woman, skim milk would be the drink of choice, since soy contains neglible amounts of calcium. Apart from allergy differences, and the different fat compositions of the two products, there is no scientific proof that there is any benefit in drinking synthetic milk (see [4]). In the two books of this person that I have read, it is sometimes difficult to decide whether the writer is naively propagating untruths as valid science, or whether she is deliberately lying to make money. --Seejyb 09:30, 18 June 2006 (UTC)
I don't know about this "mucus-lining" stuff, but there is no evidence whatsoever that drinking milk decreases your risk of osteoporosis. Check this study by the Harvard School of Public Health out. Here's a quote from the conclusion of that study: "An adequate vitamin D intake is associated with a lower risk of osteoporotic hip fractures in postmenopausal women. Neither milk nor a high-calcium diet appears to reduce risk." It's an amazing dairy-industry conspiracy - somehow everyone thinks milk keeps your bones healthy, but it just doesn't seem to be true. And as for soy milk, I don't know what Seejyb means by "a highly modified synthetic product". It's made with a very old process developed in the 1st century BC (see Soy milk) It's basically, "grind the beans in water, then strain out the milk". --Bmk 13:56, 18 June 2006 (UTC)
An article about postmenopausal woman and calcium intake has absolutely no bearing on the recommendation that woman between puberty and 30 years of age should ensure that they have an adequate calcium and vitamin D intake as well as plenty of exercise. Inferring from such a study the recommended intake for young women in the window period when calcium intake does seem to make a difference to bone density for the rest of their life is irresponsible. How we get our calcium is irrelevant, and drinking three glasses of skimmed milk, or of soy milk to which calcium has had to be added (check the ingredients), or one and a half effervescent tablet in water probably makes little difference, except to the cost of the calcium. The soy bean, when not properly ("highly") processed contains significant levels of anti-nutritionals, as well as phyto-estrogens, which does seem to worry some scientists, since the levels of intake of soy products in the western world far exceeds that of the eastern countries where soy milk was traditionally consumed. As far as conspiracy theory goes, one has the uneasy feeling that the soy-derived ingredients in processed foods may eventually turn out to be not as harmless as claimed by the very powerful producing groups; they certainly spend huge amounts of money to promote it as "healthy" or "natural", which is patent rubbish - it is as natural as coffee, at best. In the east soy was not normally used as a basic food, the way the west does at the moment, so that the long-term effects are difficult to judge impartially. This is made more difficult by the fact that interested parties tend to promote only the research that benefits themselves (e.g. dairy producers vs soy bean producers) --Seejyb 01:12, 20 June 2006 (UTC)

[edit] Stable beer

Why is it that a full can of beer seems a lot more stable when upright than the same can empty. (And dont say because its not yet drunk! Ha Ha!)--Light current 18:32, 17 June 2006 (UTC)

It's more massive, so you have to hit it harder to knock it over. I don't know if you're aiming for something more profound...? Melchoir 18:48, 17 June 2006 (UTC)
I agree with Melchoir. If you have an empty can and a full can you can do a very simple experiment to see if there really is a difference: Push the very top of the empty can a tiny bit then let go. If it doesn't fall over, push the same place a little harder, let go, repeat until it falls over. Do the same again with a full can and see if you have to push them the same distance until they fall. Obviously you'll have to push the full can harder because it is more massive, so you'd want to pay attention to distance or angle and not force. 128.197.81.181 18:58, 17 June 2006 (UTC)
Wellll... it all depends on what one means by "more stable" anyway. The major difference between the two cases will be the force, not the angle, required to tip the can. Melchoir 19:10, 17 June 2006 (UTC)

Yeah but surely the centre of gravity is about the same in both cases?--Light current 19:02, 17 June 2006 (UTC)

Maybe, but the dynamics of a rigid body are determined by its mass and moment of inertia as well as its center of mass. Melchoir 19:06, 17 June 2006 (UTC)

Aha! I think you may have hit on it here! Its probably the moment of inertia that is much smaller when empty. But Im going to do a few experiments with a large number of full, then empty cans! How they get from full to empty, Ill leave to your imagination! %-)--Light current 19:15, 17 June 2006 (UTC)

Ah, the spirit of scientific inquiry! Melchoir 19:26, 17 June 2006 (UTC)

Yes: the suffering we have to endure in the persuit of knowledge! Yes! now the result of drinking the first can experiment! Comparing a full can with an empty one I noticed that the max tipping angle was approx the same for both. (say 30 deg from vert - I didnt actually measure it). But, if the cans are pushed below this critical angle and then released, the full can regains its upright position with no oscillation, whereas the empty can totters back and forth quite a few times before coming to rest. Any ideas on that one? Anyway, must get back to the lab! %-)--Light current 19:48, 17 June 2006 (UTC)

That's quite interesting. --Proficient 19:59, 17 June 2006 (UTC)
I guess the sloshing motion of the liquid inside helps to dissapate energy, plus other factors.HappyVR 20:07, 17 June 2006 (UTC)

Yesh-- Im coming to that conclushion myshelf!! %-)--Light current 20:14, 17 June 2006 (UTC)

Well, I agree, a full can of beer is much heavier, so you have to hit it harder to fall over. Also, a "full can of beer" isn't really full with beer, it always has some amount of air in it. – b_jonas 11:45, 23 June 2006 (UTC)
Also, in case of empty cans of beers, you're probably already sligtly under the influence of alcohol, so it's more likely that you accidenatlly tip it over. Also, if the can is empty, you're more likely to hit it angrily because you've run out of beer, while with a full can of beer, you take care not to knock it over because it would be a waste to spill the beer. – b_jonas 11:48, 23 June 2006 (UTC)

[edit] Building a bomb

I'm writing a fictional work (actually a Live action roleplaying game) in which somebody needs to build a simple bomb. According to time bomb, all one really needs is a battery, a watch, and some explosive material. What kind of explosive material? Where would a teenager on a colony on Triton (a new colony, not so different from the stereotypes of the American Old West) get such a thing? Like, if there's blasting crews on the colony, could he just lift some? What are the steps involved in making a bomb? I looked for instructions for building a simple bomb online, but it turns out it's less widely available than the scaremongers would have you think. And I don't need to actually do it myself, just describe in very rough terms what would be needed. moink 19:58, 17 June 2006 (UTC)

Maybe your character can steal some c-4 from a construction site as well as some blasting caps. --Proficient 20:01, 17 June 2006 (UTC)
Just make sure to explain that you character was well-trained in his former life, including Afghan, Irish, &c. references, and do not go into bomb making details : the reader shall know enough. --DLL 20:15, 17 June 2006 (UTC)
Hmmmm... I'm trying to make him a pretty lame loser character who doesn't really know what he's doing, but does some really basic research and figures out how to build a simple bomb. We're trying to make it hard for him to accomplish this, since it screws over the other characters pretty badly if he succeeds. moink 20:18, 17 June 2006 (UTC)
Are there weeds on this colony? He could use the ever popular weedkiller ( potassium chlorate or sodium chlorate) and sugar. Theresa Knott | Taste the Korn 20:43, 17 June 2006 (UTC)
If he's not looking to do too much damage, how about the ingredients in the Gunpowder article? --hydnjo talk 20:50, 17 June 2006 (UTC)
If they farm on this colony, perhaps they have ammonium nitrate around. Powerful, common, explosive. --Fastfission 05:13, 18 June 2006 (UTC)
According to Triton (moon), there is a lot of Ammonia present. Methane and Nitrogen are abundant in the atmosphere. If you have some water, I'm sure a chemist could whip something up for you. Dmn € Դմն 11:37, 18 June 2006 (UTC)
Does it have to be a bomb, or can it just be an explosion? Any fine powder should be very dangerous if it forms a mist. See Flour and Lycopodium. The lycopodium article has links to movies. --Kjoonlee 14:51, 18 June 2006 (UTC)
Well, just something that makes sense for my character to put together from a few different pieces and "set off" while he tries to get away. I think I'me going with C-4 and some wiring and a battery. moink 07:43, 19 June 2006 (UTC)

[edit] e-mail address harvesting?

I’ve been getting a lot of e-mails from various phony senders. They are without a subject line, have no content, and are addressed to “unlisted recipients.” What is going on? Is this some kind of e-mail harvesting, or maybe something worse? --Halcatalyst 20:46, 17 June 2006 (UTC)

Can you post the header? Theresa Knott | Taste the Korn 20:51, 17 June 2006 (UTC)
An example follows. --Halcatalyst 21:33, 17 June 2006 (UTC)
Received: from ams018.ftl.affinity.com 

(lvs00-fl-n18.ftl.affinity.com?[216.219.253.56](misconfigured sender))

          by sccqmxc94.asp.att.net (sccqmxc94) with ESMTP

          id <20060617165739q9400idrkae>; Sat, 17 Jun 2006 16:57:39 +0000

X-Originating-IP: [216.219.253.56]

Received: from cust_req_fwding (xxx@dendurent.com --> x.xxxxxxxxx@mchsi.com)

        by ams018.ftl.affinity.com id S1610159AbWFQQ5j for

        <x.xxxxxxxxx@mchsi.com>; Sat, 17 Jun 2006 12:57:39 -0400

Received: from [82.155.63.77] ([82.155.63.77]:61959 "HELO fdah.com")

        by ams018.ftl.affinity.com with SMTP id S1608422AbWFQQ5j;

        Sat, 17 Jun 2006 12:57:39 -0400

Message-Id: <S1608422AbWFQQ5j/20060617165739Z+11389@ams018.ftl.affinity.com>

From:   <xxxxxxxxx@fdah.com>

To:     unlisted-recipients:; (no To-header on input)

Date:   Sat, 17 Jun 2006 12:57:39 -0400
Durn. Can somebody tell me how to display this native? (with line breaks) Thanks. --Halcatalyst 21:38, 17 June 2006 (UTC)
Done. --cesarb 21:42, 17 June 2006 (UTC)
Thank you, CesarB! --12.217.186.109 02:34, 18 June 2006 (UTC)
It's very possible that the senders have their own SMTP servers, thereby eliminating the need to send a "To" address to another SMTP server and allowing them to directly interact with your ISP's mail servers without having to go through the regular process of specifying a "To" address to a third-party SMTP server. There are many possibilities; spammers use lots of different tricks. -- Daverocks (talk) 12:19, 18 June 2006 (UTC)
I wonder why theere is no content? Could the spammer be accomplishing something nevertheless? --Halcatalyst 13:14, 18 June 2006 (UTC)
I occasionally get spams with no content, which is rather confusing. A possibility that comes to mind is that they've set up a dummy email account to send from and they're tracking bounced emails to trim down their lists. 128.197.81.181 18:28, 18 June 2006 (UTC)
I suppose if they're sending out a couple million spams it might be useful to delete 300,000 (or even 50,000) bad addresses, especially if they have automated means to update the lists. But it's hard to imagine spammers being that concerned about efficiency. --Halcatalyst 19:18, 18 June 2006 (UTC)
I did hear that there are some spam networks who do this to wind up people who they discover trying to report their abuse (a lot of the bigger spam networks apparently buy thier own IP blocks on the black market so they can control the abuse contacts). Plugwash 00:50, 20 June 2006 (UTC)

[edit] Ergonomical Sleeping

If a futon is ergonimical to sleep on because of it's hardness, how egonomical to sleep on, is a camping mat on a hard floor? --Username132 (talk) 22:51, 17 June 2006 (UTC)

You seem to be assuming that futon has a more universal meaning than it actually does. In English, it seems to refer to any sort of folding bed, aka sofabed, though the original Japanese is something completely different and very specific. I slept on a very soft western futon during my university days.
Regardless, if I take your question to mean "If firm beds are considered ergonomic, is a camping mat on a hard floor equally so?" then I can explain why the answer is no. The futon in question (yours, I assume) isn't good for your back because it's hard, but because it only gives to a small degree (hence, firm), allowing your back to straighten instead of lying limp like it would on a very soft bed. A camping mat on a hard floor has no give whatsoever, and thus does not allow for natural body contours and ends up giving you stiff bones in the morning. As a person that rather enjoys sleeping on a hard floor, I can vouch that it is ergonomical to a certain degree, especially after long periods sleeping on a soft bed, but without a firm cushion underneath you quickly develop cricks in your neck and shoulders, and I guess that's why there are so many doctors who cure that sort of thing around these parts in Japan. freshofftheufoΓΛĿЌ 05:28, 19 June 2006 (UTC)
Retrieved from "http://en.wikipedia.org../../../r/e/f/Wikipedia%7EReference_desk_archive_Science_2006_June_17_1683.html"