Wikipedia:Reference desk/Archives/Science/2007 July 23

From Wikipedia, the free encyclopedia

Science desk
< July 22 << Jun | July | Aug >> July 24 >
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

[edit] July 23

[edit] Hereditary talent?

(Following up on a question asked here.) Is there any evidence of a genetic link to artistic talent? Can a predisposition towards a specific field be hereditary? Thanks! --S.dedalus 00:03, 23 July 2007 (UTC)

For sufficiently varied choices of possible field, I'm sure it can be. Height and weight are genetically influenced and can affect who is more likely to succeed as various sorts of athletics (think basketball players, for example). For artistic talent, I don't know, but I wouldn't be surprised if there were a weak genetic association (coupled to a strong environmental/experience component). Dragons flight 00:08, 23 July 2007 (UTC)
Note that some conditions (not diseases !), like left-handedness, manic depressive disorder and homosexuality, may be both inherited and a cause of correlated with an "artistic temperment". StuRat 03:03, 23 July 2007 (UTC)
Be careful of the word "cause." correlated and causal are tricky things. --Tbeatty 03:06, 23 July 2007 (UTC)
Good point, I fixed it above. StuRat 03:22, 23 July 2007 (UTC)
Inherit... homosexuality... interesting theory there. Anyway, I'm not sure if it's nature or nurture, but I'm sure genetics have some effect on the brain and the way it forms and works, which could easily make someone like a certain thing their biological parents do, without even being exposed to them. At the same time though, artistic parents will probably expose children to art from a young age, so they will form their minds to that --Laugh! 03:57, 23 July 2007 (UTC)

Definitely you could say that there are hereditary traits which might be extremely useful for someone who happened to be disposed towards a certain career path and having these traits might even influence that person towards a particular career, playing to your strengths and all, but I don't know about being heriditarily "predisposed"; I doubt we will ever discover the astronaut or fireman gene. For example, there seems to be a genetic component to having absolute pitch, which could in turn be useful if one decided to become a musician. As to the first question, researchers have tried to answer it by searching for a "creative gene/s" or some evidence of heritability of creative talent, with apparently mixed results. This 1973 twin study, "failed to provide convincing evidence of a genetic component in creativity" [1]. However, this more recent '93 one (login needed for full article) presents a case that the genetic component of creativity has been overlooked and that, "creativity is an emergenic trait of moderate heritability" [2]. Even if creativity does have some genetic component, which seems likely in my opinion, environmental influences still must be accounted for, and this says nothing really about how the trait might be expressed; could just as easily end up with a creative janitor than with a brilliant artist. Interestingly the same study refrences a previous familial study which looked at a bunch of professions within families, finding that, "only judges seemed to aggregate within families," so maybe there is a "judge gene". -- Azi Like a Fox 05:08, 23 July 2007 (UTC)

Well, there's the remarkable Bach family. Clarityfiend 08:43, 23 July 2007 (UTC)
Some serial killers and the like seem to be creative too so any creativity could be expressed via such an outlet Nil Einne 12:30, 23 July 2007 (UTC)
The trouble with examples like the Bach family is that you can't separate nature from nurture. That is to say, you can't tell whether the younger Bach's inherited their talent from the older Bach's in their genes - or whether simply spending all of their youth amongst amazingly talented parents and other relatives caused them to learn those skills at an early age. To test the theory properly, you'd want to look at sons and daughters of musicians who had been separated from their parents at birth and who grew up with foster parents who were not musically inclined - and also at children of non-musicians who had been brought up by musically talented foster parents - and compare their abilities with offspring of musicians who lived with their parents. However, there is strong evidence that babies hear (and possibly even enjoy) music in the womb - so even separation at birth is not necessarily enough to show that there is a genetic basis. If I had to guess, I'd bet that musical ability would be a bit of both...but that's just a guess. Musical ability is composed of so many separate skills: good dexterity, an acute sense of pitch, a creative spark, possibly an interest in mathematics - it seems impossible that ALL of those would be genetically based - or that all of them would be as a result of nurture. SteveBaker 20:42, 23 July 2007 (UTC)

[edit] Chickenpox

Hi, does anyone know why chickenpox is more active in adults than in children? Thanks. —The preceding unsigned comment was added by 58.153.96.148 (talk • contribs) 07:00, 23 July 2007.

If you get chickenpox as a kid, you retain the antibodies in your system into adulthood - so any adult who had chickenpox as a child is effectively immune to the disease. Since it's a common childhood disease, very few adults succumb to it. The disease is mild in childhood - but much nastier for adults, so this is just as well! SteveBaker 11:11, 23 July 2007 (UTC)
I think the OP wanted to know why it is nastier in adults. Capuchin 11:27, 23 July 2007 (UTC)
Oops! I misread the question. Our chickenpox article offers some suggestions, it says that people with weak immune systems, the elderly and pregnant women are all at serious risk - I guess most children don't fall into that category. SteveBaker 12:45, 23 July 2007 (UTC)
I wouldn't think that a healthy adult would have a weaker immune system than a child. But chickenpox definately would affect them more. I'm curious to see if someone can explain it :) Capuchin 12:52, 23 July 2007 (UTC)
I've always heard that chickenpox is more serious for adults than children (which leads to the practice of sending children to visit those with chickenpox so they will get it when they are young). I asked three doctors in dermatology (because I felt it was in their field). Each one said it was far more severe in adults. I asked why and they didn't know. That led to a discussion of how severe it is and the conclusion is that they've always heard it was more severe, but none of them ever had an adult patient with chickenpox. -- Kainaw(what?) 13:29, 23 July 2007 (UTC)
From my reading of the article, it appears that chickenpox is uncommon in adults, as most will have acquired immunity through childhood infection, however adults are liable to shingles which can be excruciatingly painful. DuncanHill 13:40, 23 July 2007 (UTC)
I've heard chickenpox can be a problem during or after puberty (rather then simply for adults) but no idea why. The article suggests it's true although also doesn't say why. Google doesn't help much, several sources say it's more severe but don't explain why. Some even suggest sterility in males is a possibility but this appears to be a confusion, that's mumps not chickenpox. As DuncanHill may said, it's possible some sources are confusing shingles and chickenpox which are 2 different diseases even if caused by the same virus. You can only get shingles AFTER you've had chickenpox. You rarely have chickenpox more then once. Nil Einne

[edit] Philaethria dido page and butterfly identification

Hi, while checking "Uncategorised pages" on Commons, I came across Philaethria dido, which was blanked by user not logged in, it seems from the history that the image on the page was not a Philaethria dido (Scarce bamboo page) but a Siproeta stelenes (Malachite butterfly). I don't know the first thing about butterfly species, can someone more knowledgeable than me clear this up? (I will then either nominate page for deletion or not and/or upload the image again with a correct name). Thanks in advance. Deadstar 08:18, 23 July 2007 (UTC)

I think our anonymous editor has it right. Philaethria species lack the clearly visible spur on the rear wing and the entire forewing extend considerably farther, rather than having that lobe on the anterior. Go ahead and tag the page for deletion. Bendž|Ť 10:14, 23 July 2007 (UTC)
Thank you for your help! Deadstar 10:58, 24 July 2007 (UTC)

[edit] TECH CHALLENGE ! Need source for 12 v Non-Lead acid Battery of the golf cart size ? This for some reason is very hard to find?

Need source for 12 v Non-Lead acid Battery of the golf cart size ? This for some reason is very hard to find?

If anyone can give me a concrete lead (ie verified phone or email or website ) of anyone or any company that can provide a Battery of the golf cart sizes (ie 10" long x 7" wide x 9"-11" tall) that is NOT- Lead Acid, I would really appreciate the information.

I am trying to test my patent on golf carts more than I have in the past and need to use non-lead acid types. The maximum battery size is 10.3" long x 7.3" wide x 11.6" tall but can use somewhat smaller if necessary. GOD BLESS YOU FOR HELPING! ! P.S. 10.2"= 260mm, 7.1"= 180mm, 11.6"= 295mm TripleBatteryLife 18:08, 23 July 2007 (UTC)

A quick google found this site, which will make you a custom battery pack. It might not be cheap, but they do offer alkaline, Ni-Cd and NiMH in addition to lead-acid batteries. grendel|khan 19:18, 24 July 2007 (UTC)

[edit] Moving Energy

Is there any means of moving energy out of a gravitational field without gaining or losing any energy or potential energy? Philc 16:00, 23 July 2007 (UTC)

If you count Gravitational potential energy, you could do it by converting some form of energy besides kinetic into potential energy. If you don't (and you probably don't), I think you could do it by using gravitational potential energy holding the energy you're transporting apart i.e. compressing it under its own gravity, but you wouldn't get very far, and it's pretty useless. What I think you actually mean is impossible, because if you could do it you could drop the energy and create kinetic energy from nothing, disobeying the law of conservation of energy. If you could create energy, this would be trivial, since you could just create the energy used to move your energy. — Daniel 18:22, 23 July 2007 (UTC)
Creating energy from nothing is impossible no matter where it is done. But, maybe the OP means providing an energy source for space stations without having to lift heavy batteries or power plants into orbit. I once read about a plan to capture sunlight using huge solar panels in orbit and transmit the power to the Earth's surface using microwaves. I don't see any reason why that could not be reversed with power being generated on Earth and transmitted to a space station using microwaves. Of cource there would be major concerns with safety (we wouldn't want to cook any astronauts!), cost, efficiency, etc. and something would still need to be consumed to provide the energy in the first place. 87.113.3.139 13:34, 29 July 2007 (UTC)

[edit] Double Pendulum

I was wondering how the time period of a double pendulum depends on the mass of the intermediate object and its distance from the main bob?

I suggest you read the article on Double pendulum. -- JSBillings 17:17, 23 July 2007 (UTC)
Beyond fairly small swings, a double pendulum is a classic example of a chaotic system - as such it doesn't even have anything you could reasonably describe as a period. SteveBaker 20:31, 23 July 2007 (UTC)

[edit] Rolling Up Projection Screen

I pulled down a projection screen and now I want to make it go back up. When I pull on it again, it goes down a bit and then will go back up that same amount (i.e. not rolling all the way up like I would expect). Has anyone encountered this before? What should I do? --82.171.103.231 17:38, 23 July 2007 (UTC)

WD40? But keep it away from the screen itself and any plastic parts. Wipe off any surplus.--Shantavira|feed me 19:36, 23 July 2007 (UTC)
The screen is quite new. I'm not sure it needs WD40. I was wondering if there's some technique to getting it to go back up again. --82.171.103.231 19:55, 23 July 2007 (UTC)
Oh, those things always bugged me. I've found that you have to push up on the screen as it starts back up, which helps it start it's roll-up. -- JSBillings 21:21, 23 July 2007 (UTC)
We had a recent question about a stuck starter rope on a generator, and the same answer applies here: I have corrected this problem in the past by giving the screen a jerk and quickly releasing it or pushing it upwards (you might want to "escort it " up rather than releasing it completely, so it does not get going too fast. The screen, like a roller blind, must have a brake which keeps it from rolling up, but which is released by movement upward at some speed. Of course it could have a broken spring or other fault. Edison 21:41, 23 July 2007 (UTC)

I suggest a quick tug

If you can, look inside the mechanism and see if you can work out how it works. Then you should be able to see what you are doing wrong.

In school a little jerk would often fix audiovisual equipment. Edison 20:11, 24 July 2007 (UTC)
Hey, that's no way to talk about the janitor:)) Richard Avery 07:24, 27 July 2007 (UTC)
I would suggest the highly technical procedure known as jiggling it about a bit. DuncanHill 20:24, 24 July 2007 (UTC)

[edit] Insulin

  • why in humans insuline is less in non-vegetarians ?
  • what are the reasons ?
  • And what is the funtion of insuline in the body?
  • why do docters suggest to not to take sugar content food or high carbohydrate food to diabetic patients?
  • why weak or lean persons must take high carbohydrate food to become fat ?
  • why fat persons must take protineious to become slim or lean or for there physical structure?

—Preceding unsigned comment added by 210.211.231.203 (talk • contribs) 19:44, 23 July 2007

Please understand that Wikipedia cannot provide any medical advice. I do not understand exactly what you are asking in the first 2 questions. Are you saying that vegetarians need more insulin or less insulin than non-vegetarians? The 6th question is also unclear. The answers to some of your questions can be found in Insulin. For the third question, see the section on "Regulatory action on blood glucose" in that article. Food is converted into glucose (a sugar) in the blood. Insulin allows the body's cells to use the sugar. You can find information related to the third and fourth questions in the insulin article and in the article about Diabetes mellitus, a disease in which carbohydrate metabolism is impaired. A diabetic person who eats an excess amount of sugary food or carbohydrate may develop blood sugar levels that are dangerously high. Under proper control, a wide variety of foods in moderation can be part of a diabetic diet. A doctor, nurse, dietician or diabetic educator can advise a diabetic on what kind of foods to eat, how much and how often, how to monitor blood sugar levels, how to correct high or low blood sugar levels, and the proper medications to take depending on the type of diabetes. See also Nutrition , Healthy diet and Dieting articles relevant to questions 4 and 5. If English is your second language, you may prefer the Wikipedia in "simple English" which has an article on Diabetes at [3]. Edison 20:34, 23 July 2007 (UTC)
I believe the last question is actually referring to the Atkins diet. The intake of protein does not make a fat person thin, but rather the complete lack of carbohydrate uptake causes their bodies to burn more fat than they normally would. 151.152.101.44 20:48, 23 July 2007 (UTC)
Sounds suspiciously like homework; I must remind you that Wikipedia does not do your homework, but if you have a specific part you're having trouble with (after you've done research and looked first), we'd be more than happy to help you. --71.98.4.68 00:02, 24 July 2007 (UTC)
This is not anyone's homework, as the answers to some of the questions are not straightforward. I am not sure what the first two questions mean and suspect the answer is likely to be different in a westernized culture and non-westernized culture. In a westernized culture, a vegetarian diet may still be high in carbohydrates, which provokes and requires more insulin secretion, while in non-westernized cultures, a vegetarian diet may be associated with reduced body fat and greater insulin sensitivity. People with diabetes often stay healthier if they reduce carbohydrate intake somewhat, and especially if they avoid eating much sugar, because both types of foods are likely to raise their blood sugar levels further. Insulin promotes fat storage, so it is often easier to gain weight with a high carbohydrate diet and easier to lose fat with a lower carbohydrate diet. alteripse 02:54, 24 July 2007 (UTC)

[edit] Acoustic inertance of a long thin slit in a wall of negligible thickness

Im trying to find the inertance of a long thin slit in a thin walled cavity for a speaker deign problem. Inertance is m/S^2 (where S is the area and m is the mass of the air) but 'm' cannot be defined as there is negligible wall thickness. Or should I also use an end correction for my slit? If so, what is the end correction for a slit? Is it the same as for a cylindrical tube?--SpectrumAnalyser 20:42, 23 July 2007 (UTC)

OK let me pose the question in another way. In a bass reflex loudspeaker cabinet, if you just have a port (vent) opening (square round or slitty) but no tube (ie no depth to the hole), how do you work out the area of the port knowing the volume of the cabinet and all the Thiele-Small parameters of the speaker. This info is in none of the articles on cabinets or speakers or Thiele Small parameters. Do you need to include(like you do for cylindrical tubes) some sort of end correction that gives you the 'effective' length of the tube. If not, how is the area of the port calculated?--SpectrumAnalyser 14:27, 24 July 2007 (UTC)

nobody seems to be touching this question! Perhsp no one here knows anything about it, I don't either. Do you have the formula for a cone? a hole in a thin wall would be like a cone with sides at a 180° angle. Else you could approximate the slit as infinite in length, and calculate a two dimensional result, and then multiply by the length of the slit. You may have to integrate nested semicircles centred on the slit. GB 02:04, 25 July 2007 (UTC)
I have the formula for a slit but it requires the depth of the slit but doesnt seem to need any end correction. I understand that (I think). What I wanted to know was how you calculate the area of a port for a certain box frequency if it has no depth (and therefore contains no mass of air). Do you then need to use some sort of end correction to get the effective 'length' of the port so you can then calculate the mass of the air that gives the inertance?--SpectrumAnalyser 22:18, 25 July 2007 (UTC)

[edit] Is Teflon safe to cook with?

I read the section of 'Teflon' concerned with safety, and I don't know what's true and what isn't. All the sources cited are either studies funded by DuPont or what looks like paranoid woo. (Previously, tuberose.com was used as a source; note the bits about "jagged, scary-looking chunks of synthetic chemicals that have no place in the human body" and the expression of surprise at discovering that using metal implements on nonstick cookware is destructive.) I was hoping for some kind of objective answer here, and I've been unsuccessful at finding anything. It seems ridiculous that there's no good study of the safety of such a widely-used chemical; it also strikes me as odd that there are "many published cases of health effects" related to the use of nonstick cookware, none of which I've been able to dig up. It's, of course, quite possible that my research skills are rusty, and so I come to you, the reference desk, because I'm honestly very, very confused about where the truth lies. grendel|khan 22:02, 23 July 2007 (UTC)

This is one of "those" topics where it's very hard to sort the facts from the paranoid woo, but Teflon has been around long enough that one would think that if it were really trouble, we'd have some pretty strong indications by now. On the other hand, it does seem clear that when it's overheated, its decomposition vapors are bad. And the perfluorooctanoic acid precursor/relative is bad. But the finished product, used properly, seems okay.
Atlant 01:00, 24 July 2007 (UTC)
As Atlant says, it's a controversial topic. If the Wikipedia editors who've worked hard at providing a nicely balanced and accurate presentation at the Teflon article haven't managed to give you quite the answer you're looking for, I'm afraid we duffers here at the Reference Desk aren't likely to be able to, either. (My own belief, for what it's worth, is that Teflon is metabolically a rock and is perfectly safe to ingest in small quantities.) —Steve Summit (talk) 01:08, 24 July 2007 (UTC)
The thing is, I was one of those editors (I made the decision to can the tuberose.com article) and I came here because I was looking for solid information and came up blank. I want the article to lay out the known facts rather than a list of allegations that have been made, but said facts seem awfully slim. grendel|khan 18:49, 24 July 2007 (UTC)
Okay, here's the longer answer I didn't have time to write up last night.
The impression I get (though I haven't researched it) is that this is a tough question to answer, in part because it's right on the edge of what we can detect and analyze. Epidemiology is a tricky subject.
I'm reminded of the (alleged) higher incidence of Leukemia and perhaps other cancers among people who live, work, or attend schools beneath high-voltage electric power transmission lines. Someone did a review of the 200 or so papers that had been published on this question, and found that something like 197 of them demonstrated no correlation, and three of them demonstrated a very slight correlation, right at the edge of statistical significance -- with the level of statistical significance used being 95% or 97% or something.
The thing is, if you run 100 carefully-controlled surveys observing some phenomenon, all at a 97% confidence limit, and even if there is (in reality) no correlation at all, you can expect to have three positive findings, just by random chance. Statistically speaking, those 100 studies might together show that there is a correlation, or that there isn't -- either hypothesis fits the observed data to the limit of our ability to statistically analyze it. (Actually, given that there were 200 studies surveyed, with only 3 positive outcomes, I think this lends more credence to the "no correlation" hypothesis, but I'm not a statistician so I can't say this with any, er, confidence.)
This is one reason that many people's formulation of the scientific method includes a clause stipulating that you must propose a mechanism underlying your hypothesis, not just present statistical evidence showing correlation. If you can suggest how a higher-than-usual 60 Hz AC electric field might induce leukemia, or how ingestion of PTFE could have toxic effects, people will take your right-on-the-edge-of-significance statistical observations much more seriously.
None of which really answers your question, I know... —Steve Summit (talk) 02:31, 25 July 2007 (UTC)

Serious side question, what do people know about the risks posed by decomposing Teflon at 400 C? Dragons flight 01:11, 24 July 2007 (UTC)

What food doesn't turn carcinogenic at 400°C for prolonged period of time anyway? --antilivedT | C | G 06:03, 24 July 2007 (UTC)
Most food isn't packed full of flourine... It's a serious question because I've been in the room with Teflon that was baking off and still have the results (which will never be used for food again). Dragons flight 06:24, 24 July 2007 (UTC)

I wrote a Teflon flu stub, which has since been deleted and made into a redirect to polymer fume fever. StuRat 07:15, 24 July 2007 (UTC)


Wikipedia cannot give cooking advice. Please consult your food care professional if you have any concerns. --Trovatore 07:39, 1 April 2525 (UTC)

He/she is not asking for a recipe here. I think she is justified in asking the question. It is as good as asking "Is it safe to cook in a microwave oven?". Go ahead and ask any other doubts you may have, Grendelkhan -- WikiCheng | Talk 14:45, 24 July 2007 (UTC)
I think Trovatore was just roasting us, but I know how that sort of remark can really burn one up, with some construing it as a raw deal ;-).
Atlant 17:33, 24 July 2007 (UTC)
But I just know someone here makes a decent Teflon salad! grendel|khan 18:49, 24 July 2007 (UTC)
Yes, but it doesn't really stick to your ribs. (Translation for Brits: "stick to your ribs" = "is filling"). StuRat 06:18, 25 July 2007 (UTC)