Wikipedia:Reference desk/Archives/Science/2008 June 17

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June 17

Male orgasm and analgesic chemicals

Are any chemicals with known analgesic effect released during male orgasm? 99.227.1.49 (talk) 05:43, 17 June 2008 (UTC)

The male orgasm results in the release in endorphins (and probably most of the other hormones with an analgesic effect too), as does sex in general I think but to a lesser degree, although surprisingly neither our orgasm article nor our male ejaculation article mentions this (the endorphins article does mention they are released during an orgasm). Nil Einne (talk) 06:13, 17 June 2008 (UTC)

I thought it was not really known, since it's hard to measure what chemicals are being released when someone is having sex, it would be great if they could ejaculate and then be killed instantly and slice their brain up. Anyway, don't forget oxytocin, and I'm sure a heck of a lot of other neurotransmitters, polypeptides and hormones. Oh... just read the title, not sure about analgesics. --Mark PEA (talk) 20:06, 17 June 2008 (UTC)

Ibotenic acid

Does anyone here know how ibotenic acid got its name? I have a guess but it's probably wrong ;) . Does anyone know for sure who named it and why was it named this way? Thanks, --Dr Dima (talk) 06:05, 17 June 2008 (UTC)

From a quick Google (second page) leading to [1] "The name is derived from Ibotengu-take, the Japanese designation for A. strobiliformis (Paul.) Qu?l. Eugster and Müller [ 24] , who originally discovered this compound, provisionally called it &alpha-toxin and later [ 25] named it premuscimol. After an agreement between Eugster and Takemoto (26), the name ibotenic was retained". N.B. Anyone is welcome to use the source which appears to be an RS to improve the article Nil Einne (talk) 06:19, 17 June 2008 (UTC)

Well done Nil Einne! Thanks a lot. I missed that ref... --Dr Dima (talk) 06:40, 17 June 2008 (UTC)

Formation of peptides

The wikipedia article on Abiogenesis states that: "Polyphosphates cause polymerization of amino acids into peptides" Can anyone please state a chemical equation which serves an example verifying this fact?Leif edling (talk) 06:45, 17 June 2008 (UTC)

Can't find an exact equation bit I found some papers describing the "mix" and conditions they used, but I can't access the rest of the full article... (https://doi.org/10.1007%2FBF01732355) (https://doi.org/10.1007%2FBF02100094) Try checking the who this paper cites function if one exists and you probably be able to track down the seminal works. 71.77.4.75 (talk) 19:52, 17 June 2008 (UTC)

North

Is north existing on other planets than Earth? --Kr-val (talk) 08:13, 17 June 2008 (UTC)

Yes, in both the magnetic and geographic (rotational axis) senses. In fact there's an earlier question on this page (which will soon go to the archives) about the Martian north pole. The relevant article seems to be Poles of astronomical bodies. -- Coneslayer (talk) 11:32, 17 June 2008 (UTC)

But not all other planets. Some lack a significant magnetic field, for example. It seems less likely that a planet would not have any rotation, but it's possible, I suppose. StuRat (talk) 14:34, 17 June 2008 (UTC)

allopathy

what are the uses of allopathy —Preceding unsigned comment added by 59.98.34.248 (talk) 12:31, 17 June 2008 (UTC)

Have you read our article on allopathy? You can find articles in Wikipedia by using the 'search' box in the panel on the left side of the screen. TenOfAllTrades(talk) 12:55, 17 June 2008 (UTC)

Allopathic medicine is often referred to as "western" medicine. Osteopathy could also be considered western because it has come to incorporate alot of allopathic theory, but most allopathic folk consider it to be quackery so it has been largely marginalized as an alternative medicine theory. If you have ever been to a major hospital, internist, or general pracitioner then chances are high you've experienced allopathic medicine first-hand. --Shaggorama (talk) 06:32, 18 June 2008 (UTC)

Allopathy is a 19th century term that was introduced by homeopaths to describe practitioners of all other healing methods besides homeopathy. It was inaccurate then and is even more inaccurate now when used to describe scientific, western, conventional, or non-placebo medicine. Dalembert (talk) 20:28, 18 June 2008 (UTC)

From the medline medical dictionary [2]:

• Allopathy: 1. a system of medical practice that aims to combat disease by use of remedies (as drugs or surgery) producing effects different from or incompatible with those produced by the disease being treated. 2 : a system of medical practice making use of all measures that have proved of value in treatment of disease.
• Homeopathy: a system of medical practice that treats a disease especially by the administration of minute doses of a remedy that would in healthy persons produce symptoms similar to those of the disease.
• Osteopathy: a system of medical practice based on a theory that diseases are due chiefly to loss of structural integrity which can be restored by manipulation of the parts supplemented by therapeutic measures (as use of medicine or surgery).

--Shaggorama (talk) 06:35, 20 June 2008 (UTC)

Photons

Hi! I'm a high school student and I'll be grateful if anyone can clear this doubt of mine- Does photons have mass(any mass at all, however negligible)? According to the De-Broglie's equation, λ= h/mv, it should have mass, or wavelength will be infinite, won't it?(correct me if I'm wrong). And again, if it has any mass at all, substituting in the equation, m= m₀/ sqrt(1- v2/c2), light will have infinite velocity, as light travels at the speed of light..................So, can anyone explain to me if photons ahve mass?? Thanks in advance. 116.68.76.173 (talk) 14:33, 17 June 2008 (UTC) 15-year-old

Photons are funny creatures. By definition, they have no rest mass, but a photon does have momentum p = hν/c. In the de Broglie relations, the formula you've provided is a derivation that applies to and works only for particles with mass. The original formulation, λ = h/p, gives the correct wavelength for photons (λ=c/ν). TenOfAllTrades(talk) 14:50, 17 June 2008 (UTC)

Well, it's not by definition that they have zero rest mass. It's an observed contingent fact about the world. There's a reasonably well-developed theory of how things such as Maxwell's equations would be different if photons had nonzero rest mass. Comparing this with observations leads to an extremely small (but positive) upper bound on the photon rest mass. --Trovatore (talk) 00:14, 18 June 2008 (UTC)

You might also be interested in division by zero. --Sean 16:36, 17 June 2008 (UTC)

See Mass in special relativity and Photon. --Prestidigitator (talk) 23:57, 17 June 2008 (UTC)

The equation you gave for wavelength, λ= h/mv, is incorrect, that is the non-relativistic approximation. The correct equation, given in our article on the de Broglie hypothesis is

$\lambda ={\frac {h}{mv}}{\sqrt {1-{\frac {v^{2}}{c^{2}}}}}$

With this equation, the term under the square root sign is zero, and the mass is zero too, so you end up with zero divided by zero, which is indeterminate. So the wavelength is not infinite, it's just not specified by that equation. It is specified by other equations, as TenOfAllTrades pointed out. -- Tim Starling (talk) 17:48, 18 June 2008 (UTC)

That's equivalent to using the original equation, but with relativistic mass, right? Light does have relativistic mass, so that would get an answer. — DanielLC 19:04, 19 June 2008 (UTC)

Safest, Richest Country in the World?

What is the safest, smartest, healthiest, happiest country in the world with a high GDP? And, how hard would it be for a US citizen to move there? --Anthonygiroux (talk) 17:33, 17 June 2008 (UTC)

You'll need to better define your terms if you want a definite answer. "Safest" and "smartest" are particularly vague, and you've given no indication as to the weight assigned each. — Lomn 17:37, 17 June 2008 (UTC)

"safest" - low crime; "smartest" - superior educational system compared to the US. --Anthonygiroux (talk) 17:39, 17 June 2008 (UTC)

• List of countries by homicide rate
• List of countries by literacy rate
• List of countries by life expectancy
• Quality-of-life index
• List of countries by GDP (nominal)

You may also be interested in the list of countries by Human Development Index, an amalgam that may be similar to what you're looking for. Incidentally, all these lists are cross-linked from each other, along with many other such measures, in the relevant infobox. — Lomn 18:04, 17 June 2008 (UTC)

And List of countries by GDP (nominal) per capita as the non-per-capita figures don't really relate well to standard of living. Fribbler (talk) 18:17, 17 June 2008 (UTC)

True, though I don't know that either is strictly relevant to an individual. One's own salary would seem to be of greater import. — Lomn 19:04, 17 June 2008 (UTC)

Relative salary is what's important. In the US, $50,000 a year would be middle-class in most of the country. In India, it would make you upper-class, and in some parts of Africa, it would make you one of the richest people. --Carnildo (talk) 21:36, 17 June 2008 (UTC)

Canada might be a good choice for someone in the US, as it's close, relatively easy to move to, the culture shock isn't that much to overcome, and they speak English. They also rate reasonably well in all those categories listed above. StuRat (talk) 21:22, 17 June 2008 (UTC)

For that matter, simply moving within the US is likely to meet all the specified criteria, and is certainly the easiest way to accomplish the move. — Lomn 21:52, 17 June 2008 (UTC)

If you want a city, check out World's Most Livable Cities. You have to go a long way down to find an American city, however. Further to the above this goes into more detail about methodolgy and discusses safety rankings. Gwinva (talk) 08:19, 18 June 2008 (UTC)

Note that Vancouver, Canada is 4th on the list, and the first city on the list where English is the native language. StuRat (talk) 13:18, 18 June 2008 (UTC)

There's also the Global Peace Index which delivered rankings in May this year. A report here in Oz claimed we came 10th – they lied! For a non-gun culture nation, we came a lousy 27th and dropping. Very disappointing. :( Julia Rossi (talk) 00:01, 19 June 2008 (UTC)

Well, if you're throwing that into the equation, there's one clear answer: Auckland, New Zealand: the only place in the top five in each list. English speaking, too. (Julia: the 10th ranking might refer to Sydney, on the Cities list??) Gwinva (talk) 00:12, 19 June 2008 (UTC)

Ah, that's better, though Sydney strangely tops a list of other Australian cities I would have thought were safer, smaller, friendlier including others that weren't listed like the nation's capital. Julia Rossi (talk) 02:01, 19 June 2008 (UTC)

Some european countries have a higher per-capita GDP than the US, particularly the micro-countries, and (being european) very much lower murder rates. As far as I recall Luxembourg has the highest GDP per capita (PPP) I think. See List of countries by GDP (PPP) per capita 80.0.101.122 (talk) 22:41, 19 June 2008 (UTC)

If it is important to you, you might want to also consider the Index of freedom. Mac Davis (talk) 02:47, 20 June 2008 (UTC)

future in biotech ???

i need help regaridng biotech program,wat courses does it offers and is there any good future in india or any other countries ?please let me know. i am student and wanted to take biotecnology course ,so ,kindly suggest me to take or not , thanks . —Preceding unsigned comment added by 123.176.45.2 (talk) 18:30, 17 June 2008 (UTC)

Please see the Wikipedia article on Biotechnology to see what biotechnology is. Biotechnology is a very "hot" field with many career opportunities. India's market in biotechnology seems to be growing from the information I see here. A little ways down in the same article, they indicate that many Indian biotech companies are lacking qualified employees, so it seems there are probably many well paying careers. Biotechnology covers a lot of different subfields such as development of Pharmaceutical products, Genetic testing, Creating special crops for higher yield or parasite resistance, genetic engineering, bioinformatics, biomaterials, stem cell research, and many, many others. Classes in genetics, cell biology, molecular biology, biochemistry, and developmental biology are relevant to Biotechnology. Before you can take these classes though, make sure you have taken basic level science courses. If you need specific advice you should consult professors, advisor, or professionals. 71.77.4.75 (talk) 19:08, 17 June 2008 (UTC)

You may want to speak to a college counselor. --Shaggorama (talk) 06:34, 18 June 2008 (UTC)

kidney transplant

My cousin is A- blood group and i am B+ blood group is there a way i can still donate my kidney to cousin —Preceding unsigned comment added by Shelleytes (talk • contribs) 20:09, 17 June 2008 (UTC)

Kidney transplantation#Compatibility discusses blood types and compatibility. We are unable to provide medical advice here; you should check with your doctor (or your cousin's doctor) about the particulars of your case. Best of luck. -- Coneslayer (talk) 20:15, 17 June 2008 (UTC)

Has it been done? Sure:[3]. Is it common. Not by a long shot, ABO incompatability transplants are still experimental. Would the surgeon consider using the technique in this case? Thats up to him/her. Theres no harm in asking their opinion. Fribbler (talk) 20:24, 17 June 2008 (UTC)

"In 2004 the FDA approved the Cedars-Sinai High Dose IVIG protocol which eliminates the need for the donor to be the same blood type." - It can be done, not sure about the statistics of rejection with this method, though. You really need to consult your physician on this one, pal. Regards, CycloneNimrod ^talk?_contribs? 20:26, 17 June 2008 (UTC)

You'll need to consult with your cousins doctors on this one, not just because we can't give medical advice here but because there's more involved than blood type. I hope your cousin gets better and/or finds a kidney. --Shaggorama (talk) 06:38, 18 June 2008 (UTC)

Einstein and the Atomic Bomb

What's the relationship between Einstein's work on general relativity and the development of the atomic bomb? Is it unlikely that the bomb could have been created without the theory of general relativity as a foundation? E^robson (T^alk) 22:31, 17 June 2008 (UTC)

Does this help? Fribbler (talk) 23:24, 17 June 2008 (UTC)

It does, thanks! This is interesting: "According to Szilard, Einstein said the possibility of a chain reaction 'never occurred to me', although Einstein was quick to understand the concept." E^robson (T^alk) 23:37, 17 June 2008 (UTC)

Einstein was always a bit slow! ;-) Fribbler (talk) 23:51, 17 June 2008 (UTC)

You could have created the atomic bomb without General Relativity—none of its effects fall under General Relativity's auspices (they are too small). The specific mass-energy equivalence formulae (E=MC^2) itself does fall under Special Relativity, but fission itself is non-relativistic. See E=MC2#Nuclear_energy_and_popular_culture. As Robert Serber put it:

Somehow the popular notion took hold long ago that Einstein's theory of relativity, in particular his famous equation E=mc2, plays some essential role in the theory of fission. Albert Einstein had a part in alerting the United States government to the possibility of building an atomic bomb, but his theory of relativity is not required in discussing fission. The theory of fission is what physicists call a non-relativistic theory, meaning that relativistic effects are too small to affect the dynamics of the fission process significantly.

Einstein had a small role in the development of the atomic bomb—the little bit of work that was done because of his letter was not much, and its main significance is that it got Roosevelt interested in the possibility in the first place, which paved some of the way for others (esp. Vannevar Bush and Ernest Lawrence) to push Roosevelt towards making it a much bigger project in 1942. --98.217.8.46 (talk) 16:49, 18 June 2008 (UTC)

^Pretty much. He just wrote a letter to the president saying atomic weapons would be useful. While the theory of general relativity is of minor importance to the atomic bomb, the theory of special relativity is of importance to the relativistic bomb, especially when calculating the amount of energy released. ScienceApe (talk) 17:51, 18 June 2008 (UTC)

Coriolis effect and cyclones

Question moved from Reference Desk Talk Page. Fribbler (talk) 22:38, 17 June 2008 (UTC)

Can the coriolis effect be explained as an effect of conservation of angular momentum with respect to Earth's axis (or any other rotating system)? I understand that the acceleration of cyclones and hurricanes is due to conservation of angular momentum with respect to the center of the cyclone itself, as air close to the ground moves inwards. /Yvwv (talk) 22:34, 17 June 2008 (UTC)

Enough Data?

Hello. My school year ended. This reference desk is one of the few places where I can ask questions. I pulled the following question from a physics textbook:

Some sea birds, such as the royal tern, dive from considerable heights into the water to catch fish.

a) By how much does the velocity of a royal tern increase each second, ignoring air resistance?

b) How long, in seconds, does it take a falling royal tern to increase its velocity by 15 m/s?

c) What is the final velocity of a royal tern just before it hits the water after falling from rest for 1.75 s?

My book earlier mentions that the acceleration due to gravity is 9.81 m/s². I doubt that it has anything else relevant. Do I have enough data to answer the question above? Thanks in advance. --Mayfare (talk) 23:46, 17 June 2008 (UTC)

Yes. WilyD 23:49, 17 June 2008 (UTC)

Here's a hint... While the classic gravity experiment involved dropping a large and a small ball from the tower of Pisa, it may as well have involved dropping a royal tern and a common tern from a seaside cliff. If air resistance is ignored, which would fall faster? -- kainaw™ 00:54, 18 June 2008 (UTC)

It should be noted that the popular belief about the experiment is apocryphal; in reality, Galileo rolled balls down inclined planes (see Galileo Galilei#Physics). As for the original question, 9.81 m/s^2 can be written as 9.81 m/s/s. --Bowlhover (talk) 05:36, 18 June 2008 (UTC)

The use of a bird is actually a bad one. You also need to assume that the bird is falling like a rock -- no wing flapping, and no horizontal component of motion. — Lomn 01:38, 18 June 2008 (UTC)

Spherical bird in a vacuum, it's a physics problem. WilyD 01:52, 18 June 2008 (UTC)

See also Spherical cow. -- Coneslayer (talk) 14:43, 18 June 2008 (UTC)

Don't try to make this more complicated than it is, nothing more than multiplication and division is needed here. (Now, if you want to answer some questions here in return for the answers you've been given, that would be great, since, after all "one good tern deserves another".) StuRat (talk) 02:46, 18 June 2008 (UTC)

Is it carrying a coconut? If it is it may not be able to maintain minimum flight velocity.--Shniken1 (talk) 03:27, 18 June 2008 (UTC)

Equations of motion may help you here (at least for part c). AlmostReadytoFly (talk) 08:52, 18 June 2008 (UTC)