Wikipedia:Reference desk archive/Science/2006 October 11

From Wikipedia, the free encyclopedia

You have new messages (last change).
< October 10 <<Sep | October | Nov>> October 12 >
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.


Contents


[edit] Tryptophan versus melatonin

What would be the fundamental difference in ingesting a dietary supplement dose of tryptophan versus one of melatonin? If tryptophan eventually becomes melatonin, would they have a similar effect on the body? However, since tryptophan also becomes serotonin, is it safe to say that it boosts the level of the neurotransmitter to also help with depression? Finally, what would a doctor consider between the two before recommending one to a patient for sleep aid? Sybil Gray 03:15, 11 October 2006 (UTC)

Tryptophan is a precursor for many important molecules used in the body, and cannot be synthesized in humans, thus it is considered an essential nutrient. As you have mentioned, melatonin can be made using tryptophan. In general, all you need to take (in this simplified model) is tryptophan. As long as there is enough tryptophan the body will make the appropriate amount of downstream chemicals, such as serotonin and melatonin. If, however, there exists an error in one of the pathways for these downstream chemicals, such as mutation or downregulation of an enzyme in the pathway, one may end up with a pool of downstream ligands that is less effective than normal. Depression is thought to be due to a paucity of serotonin in the synaptic cleft, as you intimated. Therefore it is theoretically possible for depression to be caused by low tryptophan. However, a drop in serotonin probably would not be an immediate effect of tryptophan shortage, and certainly would not be the first clinically relevent change, as many many important chemicals (and even other amino acids) are made from tryptophan. Depression is more likely to be caused by a change in a protein that controls the formation, release, binding, or reuptake of serotonin than a decrease in building blocks. So with that primer, to answer your questions in order:
What would be the fundamental difference in ingesting a dietary supplement dose of tryptophan versus one of melatonin? --Tryptophan would give your body the choice to make lots of different chemicals, melatonin would not. If tryptophan eventually becomes melatonin, would they have a similar effect on the body? --No since tryptophan also becomes serotonin, is it safe to say that it boosts the level of the neurotransmitter to also help with depression? --No what would a doctor consider between the two before recommending one to a patient for sleep aid? --Present complaint, Past medical, surgical, social, and family medical history, Allergies, genetic predispositions, presence of phenylketonuria or alkaptonuria.... maybe you should ask one.
Ask your doctor if she thinks it is necessary to take these or any supplements/medications for your problem.Tuckerekcut 04:01, 11 October 2006 (UTC)
  • Thanks a bunch for your thorough answer. Sybil Gray 20:06, 11 October 2006 (UTC)

[edit] Methane for CO2 manufacturing?

Are there any process available for produce CO2 for the beverage industry using Methane gas? I'm interested in a design of an anaerobic digester which produce Methane and CO2 for some wastes....

So want to know about any processes involved in converting Methane to CO2..!!!

Is Burning of Methane to produce CO2 is effective? Can we collect CO2 which release from burning Methane in a easy procedure??

A Detailed answer will be very useful...Thanks...!!!

Sithara from Sri Lanka

You certainly can collect carbon dioxide from methane combustion, or directly from fermentation. However, to produce sufficiently pure carbon dioxide for use in food production, it is apparently necessary to apply various treatments to reduce impurities in the collected stream. I'm no chemical engineer, but it appears to be a reasonably complicated, multi-stage project to do so.
A google search on "carbon dioxide production", turned up Witteman, which sells complete CO2 production/recovery systems for the beverage industry, and Johnson Mathey Catalysts, which sells catalysts which are used as part of the purification process.
I hope these links serve as a useful starting point. --Robert Merkel 05:01, 11 October 2006 (UTC)

[edit] belly

ahhhh! why is one side of my belly bigger than the other. And do i have to do excercises such as running to get a six-pack, can't i just do sit ups.

The front always sticks out more than the back.... --Zeizmic 12:35, 11 October 2006 (UTC)
Think of it this way: you already have a six pack, it's just covered by a keg of fat. Doing sit-ups will make the six-pack more pronounced, but it will not be obvious unless you lose the fat covering it. To lose this fat, you must do excersizes that help you lose body fat. The body doesn't really care where the fat it uses for energy comes from, so people tend to lose fat slowly from all over their body rather than from a specific place (even if the excersize is for muscles in a specific place). Since aerobics will burn more fat in the long term, they are your best bet for revealing your six pack, and getting healthier at the same time. And please sign your posts, click the sour squiglies below the text creation box where it says "Sign your name". If one side of your belly is noticably bigger than the other, you should get checked for these conditions, and possibly more, and probably in this order: having to poop, having just eaten, scoliosis, and hepatomegaly (if right is bigger).Tuckerekcut 13:39, 11 October 2006 (UTC)
If requesting medical or legal advice, please consider asking a doctor or lawyer instead. A doctor could rule out tumors or rupture. That said, a combination of exercise (to build up the six-pack muscles) and sensible eating (to get down to a healthy weight) is required. Edison 14:32, 11 October 2006 (UTC)
Haha, "legal"?! Aren't we getting overly paranoid now? Must…not…get…sued! :-) —Bromskloss 19:10, 11 October 2006 (UTC)
See a doctor. I don't know whether or not it's physically possible for you to have my experience, but one side of my belly used to be bigger than the other, and it turned out that I had an ovarian cyst and the lymph nodes in my groin on the same side were swollen. Anchoress 19:13, 11 October 2006 (UTC)
Who says it's a guy? — X [Mac Davis] (SUPERDESK|Help me improve)
I certainly didn't, and a quick scan of the other replies indicates that no-one else did either. Anchoress 04:31, 12 October 2006 (UTC)
  • In my experience, it's mostly men obsessing about their sixpack. Women just want to be slim, not neccesarily have a sixpack. - Mgm|(talk) 09:59, 12 October 2006 (UTC)

Because your body is not absolutely symmetrical. You won't obsess over things like that once you hit, say, 24. -THB 10:34, 16 October 2006 (UTC)

[edit] rethinking science!

hi, has anyone heard or read the book THE FINAL THEORY ?because this book denies what we've known till today including newtons and einsteins laws!please do tell me if you have read the book!

I just read some comments. It appears to be quasi-religious in that people who oppose it, can't read through the whole book, and people who read the whole book just want to discuss it with their own tribe (because partial-readers couldn't possibly understand the magnificence of it all). Reminds me of other such books in the past. --Zeizmic 13:47, 11 October 2006 (UTC)
It's lauded by some non-scientists. That's about it. People without knowledge of topics are often very opinionated about them, but that doesn't make their viewpoints any more correct. This seems to be quite a problem in science, unfortunately. -- Consumed Crustacean (talk) 21:18, 11 October 2006 (UTC)
Final Theory makes me roll on the ground laughing. Just look at the example below:
Q: But don't we know all about the gravity of Black Holes and how even light can't escape?
A: No. This often-repeated error is based on a simple oversight. Black Holes are said to form when a star expends its nuclear energy and collapses. But starlight only shines from intact, functioning stars, of course. There is no more reason to expect light to shine from Black Holes than from a burnt-out, smashed light bulb. This is a commonly repeated error in plain view that is intended to showcase and dramatize our scientists' deep understanding of Black Holes and gravity, but which actually exposes how little they truly understand about either.
  • Conventional Physics sez "No light comes from black hole because its gravity is so strong that even light cannot escape."
  • Final Theory sez "A black hole is a star that produces no light because it is simply a burnt-out corpse."

This book The Final Theory: Rethinking Our Scientific Legacy (Paperback) by Mark McCutcheon is a genuine work of art. It's the funniest book, I have ever read in my life. It's the ultimate achievement of human stupidity in the field of natural philosophy.

Holy crap, that did come from the book's website. Let me retract my previous politeness. This is clearly insanity. From what I can see (from the above question, the sample chapter, the sane reviews, etc.), the book ignores empirical evidence and spews out good sounding nonsense regarding physics which on its face sounds reasonable to people who have absolutely no knowledge of the topics at hand. It also glosses right over the mathmatical backgrounds of the existing theories. :/ -- Consumed Crustacean (talk) 17:14, 12 October 2006 (UTC)
Yup, it's perfect for the clue-immune echo chamber that is its target audience. At least I hope that's all who read and believe, rather than being swayed to believe any of this ridiculous crap. DMacks 18:38, 12 October 2006 (UTC)

[edit] Quantum field theory

we know that schrodinger equation is associated with a non relativistic single particle,moving onto relativistic description of the single particle, we get klein gordon equation and then modified dirac equation.Now in QFT, when we quantise the field we see that both Klein gordon n dirac pictures get modified to many particle picture and also a single particle state is described by the field.so my question is do we discard the wave associated with the particle here as given by schrodinger equation (as here we r associating a field with single partice).if not, then also how do we get to know that is it a wave or field assocaited with the single particle.if the answer is that the particle is relativistic then it is field associated with it n if it is non relativistic then a wave is associated with it. Then the confusion lies in the fact that we know that beta decay is explained by QFT, then is it so that the neutron there is relatistic which goes to proton and other new particle, but that also can not be the case as in other case of Z0 getting produced at rest then it decays to other particle states which are again explained by QFT and here the particle is not relativistic so how can we associate a field with it.can u plzz tel where i m missing the concept.Its very important for me to understand this!!!!!!

This scores a 'Rudeness Scale of 1' (insert standard response here). You didn't sign, and it gives me a headache to try to get through the 'txt'. Perhaps there are more brilliant (and patient) people out there... --Zeizmic 13:51, 11 October 2006 (UTC)
Seems not rude at all to ask a detailed question and say "plzz" in asking for help. Wish I had a clue about the answer.Edison 14:35, 11 October 2006 (UTC)
I think the "rude" aspect comes from the fact taht this person does not seem to deem us worthy of proper formatting or spelling, and instead has peppered what would otherwise be a perfectly fine question with the lingo of an teenage instant message conversation. It makes it pretty hard to take seriously, and it is quite unpleasant to try and read through. If they don't have enough time to type out a clear question, how can they expect us to take the time to type out a clear answer? --Fastfission 00:41, 12 October 2006 (UTC)
I'm fairly certain it's not a sensible question, either. I'm getting a strong impression the questioner is quite a bit out of his/her depth here; You can't carry over Schrödinger equation solutions into the Dirac equation. --BluePlatypus 05:12, 12 October 2006 (UTC)
I agree that not using punctuation is slightly rude, but the "plzz" compensates. Now, let's go to business and try answering the question, ok?

So, I think, there is just a confusion over the terms wave and field. An electromagnetic field, e.g., is the property of space of having electric and magnetic forces of varying strength at varying places. Now, if these oscillate, i.e., change in magntidue and sign periodically, we call it a wave. Now, quantum mechnichs has always been lax about this distinction. First, a wave packet, i.e. a quantum-mechanical particle, which is half-way localized does not oscillate in the magnitude of its field, only the phase rotates periodically. (Hope you know enough about Schrödinger's equation to understand what I mean.) NOw, what does quantum field theory (QFT) add to this: As long as their is only one particle, and energies are so low that we ca neglect particle--antiparticle pair creation, everything stays the same. Only we call it a field instead of a wave. If we have two particles, we have to take care of quatum statistics ad correlations: We should not associate oe wave function with each particle, but rather a joint wave function (amplitude that particle I is at point x1 and particle II at point II).See Slater determinant for details. To get a grip on the algebraic difficulties this involves, one introduces "field operators" (see second quantization). And if we then add a Lagrangian density to describe how our fundamental particle interact, and do a series expansion to take virtual particles into account and maybe even care about renormalization, the you we have mastered quantum field theory. But if you want to get an idea of this without having to study physics to a Master's degree, you might like Richard Feynman's classic little book QED -- The strange theory of light, which explains the essence of quantum field theory for the layman. Simon A. 06:41, 12 October 2006 (UTC)

[edit] Colours

What colour is a mirror? Englishnerd 15:57, 11 October 2006 (UTC)

Silver? Melchoir 17:36, 11 October 2006 (UTC)
In the technical sense, most mirrors have no colour as they reflect all frequencies within the visible spectrum about equally. Certain mirrors which use coloured metals as the reflective agent, use coloured glass or plastic as the transparent substrate, or dichroic mirrors do appear coloured, of course.
Atlant 18:11, 11 October 2006 (UTC)
Supposing there's an unequal reflectance - how much would it take before the human eye detected a tint to the mirror? What units would be used, "intensity vs. wavelength"? "Lumens vs. wavelength"? How sensitive is the human eye to differences in intensity? Or, to differences in wavelength, for that matter? Nimur 18:38, 11 October 2006 (UTC)
It depends a lot on whether you are making a direct comparison (with the two colors next to each other) or trying to make a comparison that depends on memory (even if only briefly). With two colours right next to each other, your eye is surprisingly good; watch MPEG-compressed video of a dark sky sometime and you'll almost certainly see the banding between slight colour and (especially) lightness differences. But if the colours being compared aren't right next to each other, your sensitivity to color and lightness variations goes way down.
Atlant 17:26, 12 October 2006 (UTC)
I would say a typical mirror is white or nearly so. When a white surface is polished enough to be reflective, it appears silver or mirrored. And of course, white reflects all colors. Mirrors can also be tinted different colors, of course. --Ginkgo100 talk · e@ 20:29, 11 October 2006 (UTC)
Most mirrors are silver - not the color silver, the element silver. You coat one side of glass with silver and put a protective coat over the silver. So, when you look at a mirror, you are looking through clear glass to a plane of silver (the element). Therefore, the question is, "What color is silver (the element)?" --Kainaw (talk) 20:37, 11 October 2006 (UTC)
Why, white, of course. :) Actually, silver says its color is silver. --Ginkgo100 talk · e@ 23:46, 11 October 2006 (UTC)
Actually a mirror is colored Aluminum. http://en.wikipedia.org/wiki/Mirror
Damn. I need to keep up on my mirror technology. So, since they use aluminum instead of silver now, the question is: What color is aluminum? --Kainaw (talk) 02:45, 12 October 2006 (UTC)
Silver. =D Hyenaste (tell) 02:52, 12 October 2006 (UTC)
Its all to do with coherence of the reflected light. If you had an incoherent mirror, it would look white.--Light current 10:38, 16 October 2006 (UTC)

[edit] REPRODUCTION

REPRODUCTION

No, it's Reproduction!

lol sex -Obli (Talk)? 16:54, 11 October 2006 (UTC)
Could someone suitly emphazi this for me? Hyenaste (tell) 01:10, 12 October 2006 (UTC)
Haha, this joke is still alive? ☢ Ҡi∊ff⌇↯ 02:56, 12 October 2006 (UTC)
Only in our memories... it seems to have been eradicated from the collective intelligence within WP... --Jmeden2000 17:49, 12 October 2006 (UTC)

[edit] vortex ring simplification

" the shell discharges , accelerating the air in the shell cylinder and channeling it into a ring, and ring of accelerated air hits the target and knocks it down"

is this a good laymans description of this weapon http://en.wikipedia.org/wiki/Vortex_ring_gun it is just air accelerated by the discharge of the black shell channled into a hills vortex right?

Robin

Retrieved from "http://en.wikipedia.org../../../r/e/f/Wikipedia%7EReference_desk_archive_Science_2006_October_11_db54.html"