From Wikipedia, the free encyclopedia

Science desk
< September 5	<< Aug | September | Oct >>	September 7 >

Welcome to the Wikipedia Science Reference Desk 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 on one of the current reference desk pages.

Contents 1 September 6 1.1 Shaving when stressed? 1.2 Manufacture of Synthetic Diamonds, Plasma TV Displays and Plasma Air Conditioners 1.3 Water flow resistence 1.4 Bones 1.5 Wireless Communication 1.6 Brown specks in irises 1.7 Orphahed clone 1.8 Wave Structure of Matter 1.9 Molecular recognition 1.10 Mendelian tetrahybrid cross ratio 1.11 Deserts around the Mediterranean due to global warming? 1.12 Do eyeballs really not grow? 1.13 Pancreatic cancer

[edit] September 6

[edit] Shaving when stressed?

When I get in a depressed-like apathetic mood (it's rare but it happens) I get the tendency to shave or trim off most of my body hair, kind of like a itch that I need to scratch. I did it again today, and I wondered why I got those sudden urges to just shave/trim everything, and I noticed the pattern. Is this correlation strange? Can it represent something? PitchBlack 03:23, 6 September 2007 (UTC)

I shave off my beard when I'm depressed. It distracts my mind from the worry as well as freshens me up (removal of dead cells, shaving lotion fragrance etc.,?). -- Sundar ^{\talk \contribs} 03:32, 6 September 2007 (UTC)

Trichotillomania is slightly different (plucking rather than shaving), but might be worth a read. —Keenan Pepper 03:57, 6 September 2007 (UTC)

[edit] Manufacture of Synthetic Diamonds, Plasma TV Displays and Plasma Air Conditioners

I would like to know the precise plasma components ( the configuration and measurements/dimension)that are vital to the manufacture of the above listed items. —Preceding unsigned comment added by Autistic49 (talk • contribs) 03:55, 6 September 2007 (UTC)

Diamond see Chemical_vapor_deposition_of_diamond

TV see Plasma_tv#Functional_details

Air possibly see Ioniser#Ionic_air_purifiers ?

Are you Jas Pal Badyal by any chance?

The above articles seem to be as much as there is here, beyond that is the 'internet' which contains much more information.

And then do your own research and come back if you get stuck.87.102.17.39 11:07, 6 September 2007 (UTC)

[edit] Water flow resistence

What is the eqation for the amount of force exerted upon an object in moving water?

Ex. If you had water moving at one meter per second in a canal and you put a one meter by one meter surface into the water flow how many pounds of lateral force would be exerted upon the object?

Thanks for any help I get! -Icewedge 05:21, 6 September 2007 (UTC)

It depends on the details of the problem, and in particular, the velocity distribution of the water within the canal. That said, the definition of pressure, Bernoulli's equation, and if necessary, the fluid mechanics continuity equation and the conservation of momentum equations should do the trick. Depending on the assumptions you make, you shouldn't need all of them. Titoxd^{(?!? - cool stuff)} 08:16, 6 September 2007 (UTC)

[edit] Bones

I had a hair line fracture in the wrist. The bones now are fused improperly. Can these incorrectly fused bones be realigned/rejoined correctly?124.30.233.102 07:23, 6 September 2007 (UTC)

Erm, this is something that you should talk to a qualified specialist about, not strangers on the internet. We cannot give medical advice. Capuchin 07:55, 6 September 2007 (UTC)

And it certainly depends on the specifics of your condition. X-rays are no doubt going to be required. --24.147.86.187 13:48, 6 September 2007 (UTC)

Really I'm amazed that someone asked this question. I mean I can understand the sort of "I have a cough for 2 weeks" kind of question but this just takes the cake Nil Einne 19:46, 6 September 2007 (UTC)

Well, not really. This could be a sort of curiously asked, "is it possible to correct bones that have broken and fused back the wrong way?" To which the answer is, of course, it's not a simple question, nor can it be specifically answered to your own situation by someone who's not a doctor. So see a doctor. Someguy1221 02:21, 7 September 2007 (UTC)

The difference IMHO is that normally people are coming here to say something like "I have this problem, should I see a doctor or perhaps I'm embrassed to talk to my doctor about this, what's wrong with me". Whereas this is the kind of question "I have a serious medical problem which I need to see a doctor about, what would my doctor tell me?". 14:40, 7 September 2007 (UTC) —Preceding unsigned comment added by Nil Einne (talk • contribs)

Make an appointment to see a doctor (either a GP or a specialist) and ask them in their official capacity as a doctor whether this is possible. Nobody who is trained or qualified to answer this sort of question will answer it here. Skittle 22:56, 6 September 2007 (UTC)

I'm not trained but I have experience of a similar situation. The bones can be realigned and fused again but it will be a surgical procedure that will cost you in time, pain and money. Whether it is worth it is up to you. Also bear in mind that broken bones can take many months to remodel after a fracture so you may be need to wait a while yet. Like I said I'm not an expert, just giving you a general opinion Richard Avery 07:33, 7 September 2007 (UTC)

[edit] Wireless Communication

Hi. Can someone please explain to me how data is actually transferred in a wireless communication. My friend wanted to know the answer to this but he doesn't know how to use wikipedia. Thanks. Cheers--Shahab 10:33, 6 September 2007 (UTC)

We have an article at Wireless which may be helpful to your friend. DuncanHill 10:42, 6 September 2007 (UTC)

I have read the article. It doesn't say how communication actually happens. At least I can't find the relevant section. What happens at the atomic level when communication happens? --Shahab 10:55, 6 September 2007 (UTC)

Atomic level may not be the right place to start - the signal is electromagnetic when travelling and electric inside the devices - you may want to look a electronics or related subjects for an understanding of this. Or can you be much more specific as to whch part you are asking about.87.102.17.39 11:14, 6 September 2007 (UTC)

Maybe electromagnetic induction could also help.87.102.17.39 11:46, 6 September 2007 (UTC)

I would also check out Marconi's early work, the radio article, and the history of radio article, to glean a basic understanding of how wireless communication started and how it is still used today. --Cody.Pope 11:33, 6 September 2007 (UTC)

how is the data is transfered in the wireless communication and what methods are used in modulation and demodulation of the original signal?Kamuali 16:09, 10 September 2007 (UTC)

Oh, and the spark-gap transmitter page. Cheers! --Cody.Pope 11:36, 6 September 2007 (UTC)

One way to think about it is that your infrared remote control is a wireless transmitter, just a very high frequency one. Light is the same electromagnetic waves as radio. The devices to transmit and receive, and the opacity of substances to the waves, and background signals are different, but that's about all. If you can understand how light can fall on a photocell to carry a signal, you can understand radio too. ←Ben^B4 13:18, 6 September 2007 (UTC)

I think the OP is looking for something more along the lines of modulation. Capuchin 14:00, 6 September 2007 (UTC)

how is the data is transfered in the wireless communication and what methods are used in modulation and demodulation of the original signal?Kamuali 16:13, 10 September 2007 (UTC)

[edit] Brown specks in irises

How do people with blue or green eyes get specks of brown in their irises? -124.254.77.148 13:44, 6 September 2007 (UTC)

The article on Eye color might be a start. It seems that there are several factors that contribute to eye color, some of which could vary across any one iris. Different amounts of melanin in the eyes can cause very different colors, so avoid the idea that green eyes are caused by a green chemical, while blue eyes are caused by a different blue chemical, and so on. At least that's my understanding. jeffjon 18:18, 6 September 2007 (UTC)

Some people believe in iridology, an alternative medicine that works on the basis that your eye colour and pattern reflects the general health state of your body. [1] However, scientific studies failed to find any support for it. That said, specks in the iris can be a result of ocular disease or isorder, such as iritis, or they can be Lisch nodules, a symptom of Neurofibromatosis type I.

However, pigmented flecks are also found naturally. Yellowish specks are thought to be due to accumulation of the pigment, lipofuscin and brown or black specks are caused by eumelanin. To understand how these form, you have to know about how the eye gets coloured in the first place. Our irises contain a layers of melanin pigment. If we have pigment on both the front and back surface, the incident light that reflects off the iris is brown. Sometimes there is little or no pigment on the front surface, then light interacts with the gray iris fibers and the iris stromal cells and reflects instead as blue. The size and spacing of the fibers and stromal cells determines the "blueness" or "greenness' of the reflected light, due to optical effects such as Rayleigh scattering, Tyndall scattering and diffraction. Most irises have similar amounts of pigment on the back surface, but some people have less and that allows for some reflection from the retina in the back of the eye. The retina reflects red due to its blood vessels, this interacts with the blues and browns to create aqua and violet iris colors. So... the brown specks are usually due to an accumulation of localised pigment on the front surface of the iris. Why this happens is not known, though, it probably has a genetic component, as many cross-bred animals show remarkble variation of pigment colour within an iris. Rockpocket 18:49, 6 September 2007 (UTC)

[edit] Orphahed clone

Is there any possibility to raise a human clone in the isolated, autonomous ovule, without a mother? And is there any scientific name for that kind of clone? —Preceding unsigned comment added by 213.172.84.211 (talk) 14:18, 6 September 2007 (UTC)

Do you mean "growing" it outside of a human female? You might want to check out the artificial womb (uterus) article. --Cody.Pope 14:43, 6 September 2007 (UTC)

[edit] Wave Structure of Matter

Hello, recently I have found this website and many others dealing on the theory of Wave Structure of Matter (WSM). I referred to the Wikipedia to check if it was a relevant theory, but I did't find any information about it nor criticism. It would be very nice if some expert could shed some light on this issue. Worth it attention or should we ignore it? --Micru 17:14, 6 September 2007 (UTC)

An article on exactly that topic used to exist, but was deleted. You can read why here. jeffjon 17:57, 6 September 2007 (UTC)

Looks like English speaking scientists would prefer to regard him as a crank - possibly because he doesn't agree with Einstein (which as we all know is anathema) - that said the theory looks 'embryonic' and very literary ('proper' scientists never like that).

It's unlikely that it will get much coverage on wikipedia. (though in fairness it should have and article)

The best bet here is to read it (if you can be bothered) and form your own conclusions87.102.17.39 18:20, 6 September 2007 (UTC)

On the contrary, Wikipedia has lots of articles about fringe theories, pseudoscience, cranks, hoaxes, and other complete nonsense (in the currently accepted/mainstream-science sense). By current standards, anything that has support in reliable sources and is written in a factual/neutral and encyclopediac style is welcome. DMacks 18:26, 6 September 2007 (UTC)

Well the article was deleted - it does look to me like one mans version of the wave/particle duality (but removing the particles!), and lacks (from what I've seen so far) much mathematical background, not bad then. I think the secondary sources would be hard to come though. Milo Wollf's page looks ok http://members.tripod.com/mwolff/, but not very notable - it's more educational than anything else. Maybe Dr. Wolff should have his own biography page - with mention of his work - seeing as that has been referenced...???87.102.17.39 18:41, 6 September 2007 (UTC)

I think you need to be more specific - different names come up "geoff hazelhurst" , "milo wolff", and quite a few others - they may not all be promoting the same idea, and may not all have the same level of competance etc etc. "Wave theory of matter" is so general that it could be applied to many ideas...87.102.17.39 18:45, 6 September 2007 (UTC)

If it's notable enough, it could have an article. I've never heard of it before, though, and I have heard of quite a few fringe theories. From a quick glance, it does look more literary than scientific. It's not at all true that proper scientists are never literary. Max Tegmark for example has written some great stuff, which you can browse on his web site - such as "Many lives in many worlds." The literary things are important and very, very proper. But if there's nothing there but literature, the result simply isn't science. The "WSM" articles discuss people's ideas about science, but they don't ever quite make contact with science itself. --Reuben 18:47, 6 September 2007 (UTC)

Yes, I can't find anything to grip on - I keep finding a lot of pictures of spherical waves - and can't really work out if this is supposed to be a new theory, or a restatement of wave/particle duality or something else. is it metaphysics or what?87.102.17.39 19:09, 6 September 2007 (UTC)

If I recall, the policy on fringe theories is basically that they need to have reliable secondary sources discussing them (agreeing or disagreeing, either way) before they qualify for Wikipedia articles. That is, fringe does not become notable unless it is discussed by that which is not fringe. So the Apollo moon landing hoax theory, which is certainly fringe, is quite notable, as it has been discussed/referenced/debunked/whatever a million times over by scholars, television stations, movies, songs, etc. But a theory which only has things written by proponents and other fringe people would not be.

Such a requirement, from a Wikipedian point of view, is logical. Without some sort of mainstream acknowledgement of the fringe theory there is no way to possibly provide NPOV without violating NOR — Wikipedians would be forced to produce the "counter-arguments" (a clear violation of NOR), or else it would simply be from the point of view of the proponent (a clear violation of NPOV).

I haven't taken any time to investigate whether this particular fringe theory meets that criteria but from what little I've read above, I doubt it. It doesn't sound like a serious enough theory to warrant external attention; it doesn't sound like a definite, testable scientific theory at all. --72.83.173.248 04:18, 12 September 2007 (UTC)

[edit] Molecular recognition

What's the fundamental reason of noncovalent bonding such as including hydrogen bonding, metal coordination, hydrophobic forces and , van der Waals forces and ...,? and depends on what characteristic of particles?Flakture 17:58, 6 September 2007 (UTC)

I would venture to say the fundamental reason is electromagnetism, and the particle characteristic you are looking for is 'existence' as it applies to photons, assuming that is what you mean. --80.229.152.246 19:22, 6 September 2007 (UTC)

I would read the article on Intermolecular force. Also, skip over all the equations the first time through :O
Mrdeath5493 20:33, 6 September 2007 (UTC)

[edit] Mendelian tetrahybrid cross ratio

What would be the phenotypic ratio of a tetrahybrid cross? Since making the Punnett square can get complicated, I followed a pattern, but I'm not sure if it's ultimately correct. Monohybrid phenotypic ratio= 3:1

Dihybrid= 9:3:3:1

Trihybrid= 27:9:9:9:3:3:3:1

Continuing the pattern, tetrahybrid= 81:27:27:27:27:9:9:9:9:3:3:3:3:1

Is that correct?128.163.170.175 19:51, 6 September 2007 (UTC)

To carry on the pattern, I think you want six 9s in the last row. But – the 3:1 ratio appears when one allele is strictly dominant over the other; the analogic case would be a strict dominance hierarchy among four alleles, and therefore showing just four phenotypes. What am I missing? —Tamfang 20:59, 6 September 2007 (UTC)

You're right, I'm only talking about complete dominance of one allele. And I don't think there should be six 9's. In a dihybrid cross, there are two of the numbers (except the first and last, or 9 and 1, while there are two 3's). In a trihybrid cross, there are three of the numbers (except 27 and 1, while there are three 9's and 3's), so it follows that there should be four of the numbers in a tetrahybrid cross.128.163.160.121 22:20, 6 September 2007 (UTC)(question poster)

To answer my own question: I guessed wrong at the meaning of dihybrid cross. —Tamfang 04:16, 7 September 2007 (UTC)

You've got the 3^m part, where m is the number of dominant alleles expressed. (This is related to the binomial distribution: the probability for each gene is for dominant to be expressed and for recessive, so to get a particular m out of n dominant has probability , which is a constant times 3^m.) To get the number of different phenotypes expressing m dominants, you want (the binomial coefficients). The easy thing to do here is to use Pascal's triangle: you get 1 of 3⁰ (0-hybrid), then 1 3¹ and 1 3⁰ (hybrid), then 1 3², 2 3¹, and 1 3⁰ (dihybrid)... so you get 1/4/6/4/1 or 81:27:27:27:27:9:9:9:9:9:9:3:3:3:3:1 (tetrahybrid). Of course, there are 2²ⁿ possible genotypes, since for each gene there are four; your counts should add up to that even power of 2 (just like the rows of Pascal's triangle sum to all powers of 2, even and odd). --Tardis 01:58, 7 September 2007 (UTC)

[edit] Deserts around the Mediterranean due to global warming?

"Most scientists now agree that the amount of carbon dioxide that humanity is producing will raise the Earth's average temperature in a way that will cause a desert-climate around the Mediterranean. Agriculture will not work and tourists will avoid going there due to the heat. The inhabitants will not be able to provide for themselves and will flee North."

Somebody said that to me in a debate about global warming. Everyone must agree that this is not true? What does the IPCC say about the risk of deserts in the Mediterranean? Does anyone have a direct link?

Thank you. Jacob Lundberg 20:17, 6 September 2007 (UTC)

Take it from the horse's mouth (the horse being the IPCC) and have a look a the summary for policy makers (a pdf, alas). On page 16, there is a map that shows how the Mediterranean is expected to be the worst hit region on Earth in terms of desertification, with precipitation down more than 20% for about half the area. Keep in mind that Spain is already very dry and close to being a desert. Dryer still and it might become one (I'm no expert, though). Also note that Northern Africa gets the very worst prognosis, while there is already a desert there. But in terms of human loss, Turkey gets hit equally hard, and that is a very populous country, with 70 million inhabitants. Actually, the wost hit region on Earth largely coincides with the former Ottoman Empire, but I'll assume that is a coincidence. :) DirkvdM 07:50, 8 September 2007 (UTC)

I just added similar images, from KNMI, the Dutch meteorological institute, showing the projected change in precipitation in terms of percentage in 2080-2099 in comparison with 1980-1999, for summer (top) and winter (bottom). DirkvdM 07:28, 9 September 2007 (UTC)

[edit] Do eyeballs really not grow?

Sometime I get e-mails that are lists of useless trivia. They usually don't bother me, but there is one oft-repeated bit of trivia that does: Eyeballs don't grow. I'm almost sure that they do, since my niece had medical problems relating to her eyeballs not growing fast enough. But then, I heard about her condition from a third party and it might have been misinterpreted. So do eyeballs grow or not? —Preceding unsigned comment added by 74.230.123.79 (talk) 20:22, 6 September 2007 (UTC)

Eyeballs grow along with every other part of your body. They stop when they reach adult size, just like most bodily organs. You could look through list of eye diseases and disorders to see if you can find anything familiar. And I guess a related question, which I don't have an answer to, is "when do eyes normally stop growing?" Someguy1221 20:48, 6 September 2007 (UTC)

Those trivia lists frequently contain erroneous facts, some of them are repeated so often that I have almost come to believe them. My favourite is the one that states "the tongue is the strongest muscle in the body". --Taraborn 21:19, 6 September 2007 (UTC)

On a very off-topic point... My favorite erroneous fact is "kangaroo is an Aborigine word for 'I Don't Know'". -- kainaw™ 23:09, 6 September 2007 (UTC)

My favorite is "A duck's quack doesn't echo, and no one knows why." --Reuben 00:21, 7 September 2007 (UTC)

The Mythbusters checked the duck quack myth - they concluded that the tail end of the actual quack sounds exactly like the first part of the echo of the quack - so whilst (of course) a duck's quack echoes, you tend not to notice it. SteveBaker 00:29, 7 September 2007 (UTC)

Hah! My team recently lost a trivia contest for failing to "know" that the body part Alfred Hitchcock was missing was one of his ears. We queried the answer, but the quizmaster said, verbatim: "We got all these answers from the Internet, so they're correct". I later checked, and of course it's a piece of non-information. The things you hear these days! -- JackofOz 00:25, 7 September 2007 (UTC)

Yep - that really makes you want to scream doesn't it! Oh well. SteveBaker 00:29, 7 September 2007 (UTC)

According to the University of Illinois Eye Center, at birth the eye is approximately 75% of its adult size, link here [2]. DuncanHill 22:42, 6 September 2007 (UTC)

Nice thread. A.Z. 03:38, 7 September 2007 (UTC)

Ah, so that's why babies seem to have such large eyes. Is it true that the ears keep on growing? Nothing about that in our ear article. And why would they want to do that?--Shantavira|^{feed me} 07:24, 7 September 2007 (UTC)

There was a recent news story (perhaps Reader's Digest) about a baby born without eyeballs. Doctors implanted tiny gel capsules in the empty sockets and sewed them shut, because the internal pressure of the somewhat spherical eyeball is what keeps the bony eye socket its normal shape. Without something in the socket, it would be undersized and the skull would look unusual. The article said that over time the capsules in the eye would be replaced with larger ones, and normal looking artificial eyeballs are eventually provided. I got the impression that the change from newborn to adult is more than was previously stated in the responses. Adult eyeballs are huge, and I just cannot picture eyeballs 75% that large in a newborn's head without him looking like a frog. Edison 13:40, 7 September 2007 (UTC)

I love the one about a goldfish's memory only being one minute long, and have always wondered how somebody measured that. Corvus cornix 16:44, 7 September 2007 (UTC)

That one's been busted too.--Shantavira|^{feed me} 17:33, 7 September 2007 (UTC)

I guess everyone here missed the two moons that happened a few weeks ago when Mars came the closest it will be in 10,000 years. Over summer, I made a habit of browsing through http://www.snopes.com to find humorous stories about how gullible people are, only to find that some wisdom I had taken for granted as fact was actually commonly-told fiction. —Preceding unsigned comment added by Runningonbrains (talk • contribs) 17:25, 7 September 2007 (UTC)

Eyeballs contain a jelly like gel kinda stuff. They're something like 60% water, and you're body can naturaly produce the stuff so I don't see why not. Yamakiri 22:58, 9 September 2007 (UTC)

[edit] Pancreatic cancer

Why is it so lethal? Is it just due to the absence of symptoms in the early stages of the illness, allowing it to develop, or is there something else? --Taraborn 21:15, 6 September 2007 (UTC)

Pancreatic_cancer#Prognosis suggests that is "partly" the reason. Other factors include the fact pancreatic cancer often recurs even after surgical removal, its position in the body makes tumours difficult to detect, it often metastasises to nearby organs early in the disease progression and it doesn't respond well to many traditional chemotheraputics. Rockpocket 22:33, 6 September 2007 (UTC)

Great answer. Thanks. --Taraborn 21:48, 7 September 2007 (UTC)