Wikipedia:Reference desk/Archives/Science/2007 March 17

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[edit] March 17

[edit] Zero gravity

Is it possible to swallow tablets with water in a place with no gravity? —The preceding unsigned comment was added by 219.88.175.202 (talk) 00:59, 17 March 2007 (UTC).

Sure.

Okay, I haven't been in space myself, and I doubt there are people reading this reference desk who have. But astronauts eat and drink normally, so there's no reason why they couldn't take pills with water. With suction and tongue action you have lots of ability to move things around in your mouth that's entirely independent of gravity. --Anonymous, March 17, 01:24 (UTC).

Yep. It's all about peristalsis. The muscles in your esophagus are perfectly capable of moving food and beverages to your stomach in the absence of gravity. In fact, it will even work against gravity, if you're standing on your head. Try not to get water in your nose if you do this at home. TenOfAllTrades(talk) 01:30, 17 March 2007 (UTC)

It's Weightlessness not no gravity, gravity always exists in everywhere. --antilived^{T | C | G} 08:30, 17 March 2007 (UTC)

c:) HS7 20:35, 17 March 2007 (UTC)

And it's not even pure weightlessness; the orbital perturbations and spacecraft trajectories usually induce some slight (time-varying) accelerations. See Microgravity. Nimur 22:39, 17 March 2007 (UTC)

You can try the worst case. You can drink while upside down. You can also open your mouth. Much to the chagrin of my high school biology teacher who said your mouth opens do to gravity. --Tbeatty 04:51, 21 March 2007 (UTC)

[edit] Electric outlets

Hello! I am taking a trip to Japan soon, so I looked up the type of electric outlets used in the country. Accoding to List of countries with mains power plugs, voltages and frequencies, a United States plug is compatible with the Japanese outlets (that is, its prongs fit in the outlet), but the U.S. outlets provide 120 V and 60 Hz whereas the Japanese ones provide 100 V and 50 to 60 Hz depending on the city. My question is, "Is it possible to plug a U.S. laptop, MP3 player, or any other device with a rechargeable battery into a Japanese outlet without any damage to the device? What about appliances that do not use batteries?" I would imagine it would be okay, since the Japanese voltage and Hz are lower, not higher, than the U.S.'s. I'm guessing it would just take longer to charge the batteries, and perhaps other appliances like hairdryers may not work as well as they would in the U.S., but I'm guessing there would be no damage. Thank you to anyone who can contribute!--El aprendelenguas 02:03, 17 March 2007 (UTC)

Your laptop's power brick should list the allowed ranges of voltage and frequency. Unless you're using devices that draw a lot of power very suddenly (pressurized rice cookers) you should be OK. --Kjoonlee 16:20, 17 March 2007 (UTC)

I don't know about MP3 players, but Koreans in Sweden say that you need to bring an old pressurized rice cooker to Sweden, or buy one made for the Swedish market. Sweden uses 50 Hz. Korea uses 60 Hz. --Kjoonlee 16:22, 17 March 2007 (UTC)

I have successfully used my US laptop, US digital camera, US cell phone charger (just to get at my phone book - the phone itself does not work in Japan) and US iPod many times in Japan. The difference between 110 and 100 is not significant, generally. As Kjoon says, your power adaptor should give you the allowable ranges. One thing you may have a problem with, however, is the shape of the plug. Some US plugs are polarized so the neutral blade that is wider than the other. Most Japanese plugs are not polarized and therefore your wide neutral blade may not fit. Also, most Japanese plugs in hotels (at least the ones I have stayed at) seem to be ungrounded. So, if you have a plug with a third prong, it will not fit. The solution is to buy a 3-prong to 2-prong converter. Instead of a fancy travel pack with lots of adaptors you don't need (at least for your current trip), you can find this at almost any big hardware store and it should cost less than $1. Finally, most hotels don't have enough power outlets to cover all the gadgets you will bring with you. Therefore, you may want to bring a small 6 outlet power strip. Johntex\^talk 20:27, 19 March 2007 (UTC)

For more info see [[1]]. Johntex\^talk 20:28, 19 March 2007 (UTC)

[edit] Properties

What are the properties of Glucose? In the article it didn't say anything about the properties. —The preceding unsigned comment was added by 76.64.135.152 (talk) 02:30, 17 March 2007 (UTC).

Many properties of glucose are listed at Glucose; what specific information are you looking for ? -- MarcoTolo 02:57, 17 March 2007 (UTC)

Where are the properties smart guy? Which paragraph? —The preceding unsigned comment was added by 76.64.136.102 (talk) 17:20, 17 March 2007 (UTC).

Please assume good faith. What exactly do you mean by "properties"? Splintercellguy 18:57, 17 March 2007 (UTC)

Well, the infobox on the right-hand side has the molecular mass, melting point, density, etc.; in general these are the basic "properties". I suppose you might be looking for refractive index values, or spectroscopy data.... It would be helpful if you would clarify which properties you're searching for. -- MarcoTolo 21:14, 17 March 2007 (UTC)

The first thing I thought of was color, which is white for powdered glucose. This is not in the article. I will add it now. Nimur 22:45, 17 March 2007 (UTC)

Then again, also the color of the glucose in the pictures was white. It could be assumed that glucose is white :) I mistook them for white chocolate! [Mαc Δαvιs] (How's my driving?) ❖ 02:02, 18 March 2007 (UTC)

[edit] Myopia

Is there any basic methods of preventing or decreasing myopia other than through the use of glasses and contactlenses or surgery. is it possible that the computer can make you're myopia so bad that you go blind? —The preceding unsigned comment was added by 219.88.175.202 (talk) 04:21, 17 March 2007 (UTC).

Rest after some length of time, give your eye plenty of rest etc. One thing I've found out is that a pair of good glasses that match your myopia will greatly slows down the rate it worsens (or so my personal experience tells me). And no, you cannot get blind from myopia from the monitor, unless you get Deep Vein Thrombosis and the clot travels to your retina or something. --antilived^{T | C | G} 08:22, 17 March 2007 (UTC)

We cannot give medical advice on this page, and that includes advice about treating or preventing myopia. There has long been debate about the causes of Myopia. The article on the subject attributes its causality to a combination of environmental and genetic factors. An Ophthalmologist would be the best person to see regarding Corrective lenses , eye training etc. Edison 15:32, 17 March 2007 (UTC)

I don't think I believe it myself, but some advocate doing focusing exercises and/or using black plastic "glasses" with many tiny holes in them, each of which acts as a pinhole lens. Carotene is also "said" to help vision, but I won't comment on this claim. StuRat 21:02, 19 March 2007 (UTC)

Carotene most certainly does help with vision. In the eye, beta-carotene is converted into a form of vitamin A called retinal. That binds to a protein called opsin in the eye. When light strikes a photoreceptor, the retinal is converted from the cis form to the trans form, which in turn causes an action potential to travel along the optic nerve. The electrical signal is processed into what we perceive as vision. People with vitamin A deficiency experience night blindness. As the depletion of beta-carotene increases, the quality of vision decreases, in extreme cases resulting in blindness. And that is why carrots help you see in the dark (though they wont help myopia) Rockpocket 02:48, 20 March 2007 (UTC)

[edit] Cleaning improves the quality of Methamphetamine

How come cleaning Methamphetamine with Acetone improves the quality of the dope?Shredder0288 07:08, 17 March 2007 (UTC)shredder0288Shredder0288 07:08, 17 March 2007 (UTC)

The chemical processes necesary for the synthesis are never 100% yield, but create side products. This side products have sometimes side effects or pharmacologic impact stronger than the substance synthezised. The Meth production is never clean nor perfect, because of this the dope contains alot of substances not only Meth. By cleaning the possible side effects could be limit to the effects of the pure substance. What solvent the right one is for cleaning depends on the nature of the unwanted side products and the difference in solubility .--Stone 13:17, 17 March 2007 (UTC)

So the quality i.e. the taste is not affected by age (shelf life) of the precursers? Only by the "side effects"?

[edit] Body odor question

Do different people develop different odours (not including factors like hygene and perfumed substances, natural body odour). If it is true can different races have distinct smells? —The preceding unsigned comment was added by 213.217.212.29 (talk) 08:51, 17 March 2007 (UTC).

Appearantly that's how new born babies identify their mother and vice versa, so yes, we all have distinct smells. --antilived^{T | C | G} 08:54, 17 March 2007 (UTC)

As far as I know they do that due to pherhormones which don't have a distint smell but induce effects. I'm talking about distinct smells which adults can identify.

Well, study of women sniffing men's dirty shirts have been done where they can identify similar smells or something. It was on an episode of Naked Science, as well as another study, but I forgot what the other one was. --Wirbelwindヴィルヴェルヴィント (talk) 09:26, 17 March 2007 (UTC)

Was reading about it in an immuno book a while back, see Major histocompatibility complex#MHC and sexual selection -- atropos235 ✄ (blah blah, my past) 18:01, 17 March 2007 (UTC)

Our article on body odor says "Body odor is specific to the individual, and can be used to identify people, though this is more often done by dogs than by humans". It also contains a reference to the fact that the Japanese thought that 17th century Europeans had a distinctive (and not very pleasant) smell - although maybe this was more due to different cultural attitudes towards bathing than any genetic difference. Gandalf61 13:10, 17 March 2007 (UTC)

I asked a similar question previously on one of the desks, because I would note that cultures have distinctive smells. I understand that people from Asia have noted that western europeans have a 'sour milk' smell. My terrible memory means I cannot remember what the answer was, but I seem to recall being direct somewhere or other. ny156uk 17:55, 17 March 2007 (UTC)

The existance of human pheromones is currently unknown. However, since humans do not have a molecularly functional vomeronasal organ, if there are human pheromones then its highly likely they are detected by the main olfactory epithelium and therefore probable that there will be a "smell" associated with the cue (cf. androstenone). So, following the logic, if there are human pheromones which, by definition, will mean different individuals will express different cues, its not surprising that different population groups have genetically predisposed differences in body odor. Of course, parsing that out from the large environmental effects (such as diet) will be extremely difficult. There is some discussion on a related question from out archives, here. Rockpocket 20:41, 17 March 2007 (UTC)

Scientifically speaking, different "races" cannot have distinct smells, as more and more study indicates that "race" is only a social construct. My personal guess about the "sour milk" thing would refer to differences between European and Asian lifestyles, perhaps something to do with diet or styles of bathing. $\sim$ Lenoxus " * " 18:53, 20 March 2007 (UTC)

Still, there has to be something. Like, if I've been to India and I come back to the US and open the bags, it smells genuinely different. OF course, this may just be me, because I can also tell if you've been outside (this only works near my house) recently by how you smell... FruitMart07 17:00, 21 March 2007 (UTC)

[edit] Growing Bamboo in my House

I am interested in growing some bamboo, purely for the reason it looks cool. But i only want a small pot plant indoors. Does anyone have any tips or tricks in growing a small specimen for a windowsill? I am a gardening novice, so the simplest option would be appreciated, tanks a lot guys Dave 12:25, 17 March 2007 (UTC)

Sounds simple but just trim it often and keep it in a small pot. Bamboo is a hardy grass and should survive a brutial cutting now and then. To grow it (from seed?) you'd need to obtain some of those white fluffy spores from a mature plant. I suggest you go on the lookout for any neighbours who have a large bamboo and just grab one of the tall storks :) If you keep it small thought it probably will never flower like a mature one. Think outside the box 13:58, 17 March 2007 (UTC)

Or you can grow a lucky bamboo. Even they're not actually bamboo, they look just like miniturized versions of them, and can be positioned so that they make heart shapes etc, and I don't think they die easily. You might want to try these. --Wirbelwindヴィルヴェルヴィント (talk) 19:20, 17 March 2007 (UTC)

Whilst browsing about for bamboo i did stumble across lucky bamboo, in all honesty though, it doesn't have the same aesthetically pleasing effect as real bamboo, rest assured i will give them a bash if nothing else turns up, or the real stuff fails, thanks anyway Dave 19:37, 17 March 2007 (UTC)

[edit] CMB and temperature of the universe

The universe has cooled signifcnatly from (30,000?)k to about 3k becuase the universe expnaded and that amount of energy was spread over a larger area. also nothing can ever get to 0k due to quantum flucations. so my question is assuming the universe keeps expanding what will be the coldest it gets to and how long approximalty would it take to get that cold?--137.205.8.2 17:24, 17 March 2007 (UTC)

Well it would be an exponential curve with an asymptote at 0K, so at t = almost infinity, it will be almost 0. -- atropos235 ✄ (blah blah, my past) 18:03, 17 March 2007 (UTC)

Sounds good, though we do have an article on the heat death of the universe--VectorPotential^Talk 19:08, 17 March 2007 (UTC)

[edit] Greenest Bottle

Take any liquid food product available at grocery stores. They are often available in different container types, such as glass, plastic, metal, or paper-based bottles. Knowing that the container will most likely find its way to a landfill after the product is consumed, I wonder which type of container is most environmentally friendly. There are so much litterature, so many variables and so many opinions about this issue, could anyone give me a simple rule of thumb to help me select the less harmful product/container for the environment?--JLdesAlpins 17:25, 17 March 2007 (UTC)

Plastic, glass, and aluminium bottles take hundreds, if not thousands of years to decompose. It would be great if you could recycle it, though. Your best bet for something enviromentally friendly is a material that takes less than a year to decompose under normal circumstances. Something directly organic should match this description, although too much organic waste can contribute to greenhouse gases, unless if that gas is used for energy. It should be strong enough to hold in liquids, but decomposable enough so that is rots easily, but not in the period of time when the bottles will be used. It also helps if it's easily recycleable. Hope this helps. A stroHur ricane 00 1^{(Talk+Contribs+Ubx)} 18:31, 17 March 2007 (UTC)

Don't worry, no containers are that "harmful" to the environment. So what if a glass bottle does not break down over the course of a thousand years (wouldn't it get broken up into smaller pieces?)? A lot of rocks don't all that well. [Mαc Δαvιs] (How's my driving?) ❖ 02:01, 18 March 2007 (UTC)

There's sort of a mythos about biodegradable materials. As Mac Davis brought up, most rocks are not biodegradable. I see no reason why a glass bottle in a landfill is any better for being in smaller pieces. If it has to go to the landfill in the first place, what difference does it make what form it takes? We should just reduce how much stuff actually needs to be disposed. Nimur 02:49, 18 March 2007 (UTC)

It's not the effect of the resulting empty container on the environment that's so terrible - it's the resources consumed in making it in the first place. Recycling this container cuts down on the environmental damage done by creating the next one. Aluminium cans are the most recyclable - glass comes second, plastic third. SteveBaker 12:43, 18 March 2007 (UTC)

Or you could buy stuff that is very much not biodegradable, then just wash it out and use it again

I would look at the resources used in making the product. Plastic is made from petroleum, which is in short supply. Aluminum has to be mined, and there isn't all that much of it readily accessible. Glass, on the other hand, comes from sand, and there is no shortage of sand in the world, nor do I expect a shortage in our lifetimes, so glass might be the best choice based on that. I also feel it is the least likely material to leech toxins into the contents. StuRat 20:56, 19 March 2007 (UTC)

[edit] Can someone identify this insect?

I found this in my house last night, and it's very odd looking. At first I thought it was a moth, but it doesn't appear to have wings, and is very hairy. Any ideas? ETA - I live in Cardiff, UK, if that's any help! Here's a link to a picture that shows that it's about half the size of an AAA battery. http://img.photobucket.com/albums/v233/snorgle/bugsize.jpg Snorgle 18:16, 17 March 2007 (UTC)

I don't know what species exactly, but based on its appearence, I suspect it's some kind of caterpillar. It may be dangerous, so don't get yourself caught inits hairs. Hope this helps. A stroHur ricane 00 1^{(Talk+Contribs+Ubx)} 18:24, 17 March 2007 (UTC)

Jesus! I nearly jumped out of my skin when I saw that (is it crawling on your shirt? There's no way I'd let one of those things stay on there!). First impressions - caterpillar, possibly poisonous. --Kurt Shaped Box 18:27, 17 March 2007 (UTC)

Orgyia leucostigma or closely related ?Mion 18:46, 17 March 2007 (UTC)

look in the Lymantriidae family. Mion 18:48, 17 March 2007 (UTC)

~~Flipping through an insect book, found that it looks very similar to a White-marked Tussock Moth. However, there's some differences.~~ --Wirbelwindヴィルヴェルヴィント (talk) 19:04, 17 March 2007 (UTC)

~~Addendum: It sees like it is a variety of the Tussock Moth, however, if you look here.~~ --Wirbelwindヴィルヴェルヴィント (talk) 19:06, 17 March 2007 (UTC)

Ok, ignore all those. It's poisonous, btw. I'm 99.99% sure it's this Brown Tail Moth in this BBC article. --[[User:Wirbelwind|Wirbelwindヴィルヴェルヴィント

Looking at various links, I'm not sure if the brown-tailed moth is the right caterpillar. It doesn't seem to have the black tussocks shown in my photo. Unless it's just variable. Snorgle 20:00, 17 March 2007 (UTC)]] (talk) 19:12, 17 March 2007 (UTC)

I think that's a nice picture, btw. Maybe you can upload it to commons and use it in the Brown-tail article? Just a suggestion. --Wirbelwindヴィルヴェルヴィント (talk) 19:17, 17 March 2007 (UTC)

I'd better make sure of what it is, first!Snorgle 20:00, 17 March 2007 (UTC)

Yes, but it looks exactly like the picture in the BBC article. --Wirbelwindヴィルヴェルヴィント (talk) 20:11, 17 March 2007 (UTC)

But they don't have the tussocks, as far as I can see. I googled for brown-tailed moth caterpillars and none of the pictures showed the dark tussocks. This one: http://www.geocities.com/brisbane_noct/images/wpe6.jpg is called Black Tussock Moth caterpillar and seems more like it.Snorgle 21:11, 17 March 2007 (UTC)

As far as I'm concerned, anything coloured like that is something to be avoided unless I absolutely, positively know what it is and know that it's harmless. --Kurt Shaped Box 19:42, 17 March 2007 (UTC)

Well, it appears that the hairs are probably at least irritating and possible poisonous, so I won't touch it! I don't know where it is now actually, as it appears to have crawled off somewhere.Snorgle 20:00, 17 March 2007 (UTC)

See Orgyia antiqua (rusty tussock moth) Cacycle 00:42, 18 March 2007 (UTC)

Ah, that looks right!Snorgle 01:20, 18 March 2007 (UTC)

Our article on Orgyia antiqua says the insect has defensive glands but doesn't say much about them. Is it dangerous to humans? It would be great if someone knowledgeable could expand the article. Johntex\^talk 20:40, 19 March 2007 (UTC)

Indeed, this is the common moth species, Vapourer. I have just reared one through pupation to hatching. A flightless female, but the bonus here is attracting wild males, mating and eggs! Certainly one of the most attractive caterpillars I've had the pleasure to meet. I have checked several sources, and the best I found was on a discussion forum, where someone said "some people find them an irritant"! I suggest therefore that they are not poisonous to people, but should be lovingly reared to adulthood or released back onto a suitable host plant (but check out it's preferences first—although they eat a wide variety of tree and shrub leaves, mine would take only dog rose out of about 10 species tested!)—GRM 20:37, 5 October 2007 (UTC)

[edit] Long, multilegged, hairy bugs

Why do pictures like the one above scare the hell out of me? Pictures of spiders and six-legged bugs don't affect me at all. I think I might've mentioned this before - centipedes and millipedes freak me out too. --Kurt Shaped Box 18:31, 17 March 2007 (UTC)

Maybe it's the hairiness? It makes my skin crawl..Snorgle 19:36, 17 March 2007 (UTC)

There's something about it that just radiates 'evil' to my eye. I know that's not a very scientific thing to say but that's my gut reaction. I'm actually worse with centipedes - I feel physically sick if I unexpectedly encounter one (say if one runs out in front of me from somewhere). If one moves towards me, I run away like someone else might run from a charging bull. I look at a picture of a centipede and I see a monster. If Hell exists, there are centipedes in it. --Kurt Shaped Box 21:55, 17 March 2007 (UTC)

It could be a cultural or socially learned behavior. Arachnophobia and Entomophobia suggest that individual traumatic experience may play a role as well. Nimur 22:52, 17 March 2007 (UTC)

Probably because biologically, we know things like that are poisonous, so it creates a fight-or-flight response in us. --Wirbelwindヴィルヴェルヴィント (talk) 22:56, 17 March 2007 (UTC)

Phobias are strange things. I know someone who is terrified of budgerigars. She cannot be in the same room as a budgie without panicking (other birds don't affect her). She says it's something to do with the way they move, the way they look at her and the appearance of their claws... --Kurt Shaped Box 23:08, 17 March 2007 (UTC)

I think that caterpillar above looks cute, but centipedes and millipedes creep me out, too. I think it's because they are fast. The faster a critter is, the more distance I need between me and it for "minimum assured safe distance". StuRat 20:45, 19 March 2007 (UTC)

could be a form of tricotilophobia (sp?) where you are scared of things being hairy or giving the appearance of being hairy(given the many thin legs they could look like hairs)Maxx4444177 17:20, 20 March 2007 (UTC)

[edit] is there a magic pill for getting smarter?

what can i do to get smarter? i dont mean like genious.. i just wanna be like a normal smart guy. right now i consider my self generally stupid and incompetent at everything. is there anything i can do about that? —The preceding unsigned comment was added by 209.53.181.36 (talk) 23:42, 17 March 2007 (UTC).

There is no magic pill for increasing intelligence. But there is certainly a lot you can do to get smarter. Doing things like maths or playing chess is good exercise for the brain. - Akamad 00:15, 18 March 2007 (UTC)

There are "magic pills" for getting smarter but they are of no use to you. Let me given you an example. You go to an african village where the people are eh, in a very bad shape so to speak. You get a random sample of the village kids and give them an intelligence test. Then you separate them into two equally sized group "control group" and "magic pill group". You give the "magic pill group" the magic pill called CENTRUM MULTI VITAMIN. After 2 months, you test the groups again. The "magic pill group" has became smarter. Thus there are such things are "magic pill" that makes some people in some situation smarter. I rest my case.

They are of no use to you because you are already smart and you are surrounded by smart people. What you want is a magic pill to make you smarter than the people around you. I'm sorry but currently there are no such pills.220.239.107.13 00:54, 18 March 2007 (UTC)

I think the above post is meant to illustrate the need for proper nutrition in order to develop a healthy mental faculty. I don't know if it's scientifically accurate to advocate Centrum vitamin supplements as a "magic smart pill." Anyway, you might want to read Flowers for Algernon, a fictional short story in which a mentally challenged man undergoes medical treatment to become a genius. The results are not quite as happy as anybody had hoped. In lieu of chemical augmentation (which might be possible, but entails a lot of risk, philosophical questions, and ethical considerations), you might just try reading more, studying harder... Several schools of thought exist. Some people advocate the idea that certain people are smarter, faster, and generally better than everybody else. They believe in things like IQ tests, quantitative descriptions of intelligence, vocational aptitude tests, and "geniuses." Other people do not believe that any distinctions can be made between "smart" and "stupid people." A wide variety of philosophies exist in between. You shouldn't be discouraged by difficult mental exercises, you should work to your capacity and study hard. Enjoy the things you study, and they will be much easier to excel at. Nimur 01:58, 18 March 2007 (UTC)

Fish is commonly cited as being 'brain food'. In my view, anything from the sea is very good in this regard. The last time I accidently ingested animal product, I felt my consciousness 'closing in'.Vranak

As some people have pointed out, I'd suggest studying and doing conscious, forceful and to some extent "painful" mental exercises to increase what we understand as intelligence. On the other hand, maybe you would like to take a look at the article smart drugs. --Taraborn 12:21, 18 March 2007 (UTC)

While the definition of "smart" is central to this question, I will assume that you want to increase your overall cognitive abilities with respect to education. If that is the case, exercise may be your best alternative to a quick fix. (http://www.msnbc.msn.com/id/17662246/site/newsweek/) While there are pills that exist that do aid in increasing the flow of dopamine and norepinephrine into the extraneuronal space (ie adderall); these are prescription pills that must be discussed with a qualified physician. XoVolition 16:52, 20 March 2007 (UTC)

[edit] Tire illision

Hi all. I was wondering what that illusion is called where the tires (well any rotating object, I guess) appears to be moving backwards? - Akamad 00:55, 18 March 2007 (UTC)

That is a special case of frequency aliasing. See this article on the Wagon-wheel effect. Nimur 02:00, 18 March 2007 (UTC)

Thank you. - Akamad 04:34, 19 March 2007 (UTC)

Also notice that this happens with the spokes on wheels. Tires are the black rubber things on the outside of the wheels, so you would rarely see that effect in tires. StuRat 20:39, 19 March 2007 (UTC)

Also happens with airplane propellers and helicopter rotors. Simply put, the rotation has increased to such a speed that is is outpacing the "refresh rate" of your eyes (i.e. the speed at which your mind processes the thousands of still images from your eyes) so each time your eye clicks over to the next frame, you are seeing the next blades at different locations so it looks like they are moving backwards. SGGH 15:12, 20 March 2007 (UTC)

Because of this, the effect doesn't require a computer (as aliasing does) — it also often shows up in film. $\sim$ Lenoxus " * " 19:02, 20 March 2007 (UTC)

Even in film, that would be called aliasing. Film image frames are time samples which convert continuous motion in to discrete photographs. Nimur 20:24, 21 March 2007 (UTC)

[edit] Can batman take pills?

Is it possible to swallow tablets with water while you are hanging upside down? 220.239.107.13 01:01, 18 March 2007 (UTC)

Should be, else people in space wouldn't be able to eat. --Wirbelwindヴィルヴェルヴィント (talk) 01:30, 18 March 2007 (UTC)

Yes. Peristalsis. [Mαc Δαvιs] (How's my driving?) ❖

Apparently the questioner has never chugged a beer while standing on his head. --Kainaw ^(talk) 05:42, 18 March 2007 (UTC)

Exactly. Astronauts would starve to death in zero-g if gravity were needed to aid swallowing. SteveBaker 12:35, 18 March 2007 (UTC)

Do not confuse upside-down-ness with zero gravity. When you are upside down on Earth, you are swallowing against gravity, whereas in space, you are swallowing in no gravity. − Twas Now ( talk • contribs • e-mail ) 11:06, 19 March 2007 (UTC)

Doesnt the trought have musles that move the food down no matter what postion your in? Maverick423 17:25, 19 March 2007 (UTC)

No, if your'e upsidown, they move it up

Your body primarily relies on gravity to swallow food, with peristalsis serving a secondary role. This explains why acid reflux disease occurs primarily when lying down, due to the loss of the gravitational mechanism. It's possible that some people may have a strong enough peristalsis to swallow against gravity, especially with training, but I doubt if it's very common. On the other hand, in a zero-g environment, just about everyone can likely manage to swallow with a bit of practice. StuRat 20:37, 19 March 2007 (UTC)

As my comment pointed out - chugging a beer while upside down is a common thing to see at a college binging party. I've never known anyone who couldn't do it (although some needed help with the cup because it is weird holding it against your upper lip). --Kainaw ^(talk) 16:30, 20 March 2007 (UTC)

Sturat, with respect, that is extremely untrue. Even my first books on human bodies, as a small child, talked about the swallowing mechanism and how it enables people to easily swallow when upside down. I have never known someone who couldn't. If you can't swallow when upside down, maybe you should see a doctor. Peristalsis is quite strong. Skittle 18:09, 20 March 2007 (UTC)

[edit] Pigs Eat Their Own Young

A while back, Pig contained this line, "Occasionally, in captivity, pigs may eat their own young." Since then, that line has been removed because it is unsourced. I have always believed that pigs do in fact eat their own young, but I can't find any citations on it (except websites which are directly mirrored from old versions of our Pig article). Can anyone conclusively end this debate so we can properly add and cite this fact (or permanently leave it out of the article)? Nimur 02:06, 18 March 2007 (UTC)

[2] ? Nimur 02:09, 18 March 2007 (UTC)

I have created Savaging to document this phenomenon, which is widely reported on numerous reputable pig sites. Nimur 02:31, 18 March 2007 (UTC)

Excellent article Nimur. [Mαc Δαvιs] (How's my driving?) ❖ 03:26, 18 March 2007 (UTC)

[edit] Labia

What is the physiological purpose (if any) of the female labia?

Probably protection of the internal genitalia. Nimur 02:30, 18 March 2007 (UTC)

I'd guess so. It'd avoid random things from accidentally getting inside. It's possible that the hymen would have a similar use. — Kieff | Talk 02:36, 18 March 2007 (UTC)

If so, why are there different sizes. Have a look at labia and this [3].

Probably the same reason why people don't look the same, and people don't have the same size penises and breasts, etc. No matter the size and shape of the genitilia, they all serve the same purposes. --Wirbelwindヴィルヴェルヴィント (talk) 03:14, 18 March 2007 (UTC)

Ah Im glad you brought up penises. You could say that the foresking was to protect the glans. now I submit that most mens foreskins always cover their glans (assuming theve not been circumcised) and therefore offer protection to the sensitive skin. In the case of labia, some are so small (or even non existent) that they do nothing to protect the vagina. So what is the purpose? Are they just vestigial remains of what would actually be a scrotum in a male? Can I have some proper medical/anthroplogical replies please?

Probably, because both the male and female organs start out the same for embryos. --Wirbelwindヴィルヴェルヴィント (talk) 04:41, 18 March 2007 (UTC)

Yes, the various vulvar structures are developmentally homologous structures to the male external sex organs (see Vulva#Sexual homology). -- MarcoTolo 04:44, 18 March 2007 (UTC)

I don't have any citations for my observation, but labia in their typical form are very functional. When swollen and moistened during arousal, they make a very convenient canal that is a definite aid to successful intercourse. Anchoress 04:45, 18 March 2007 (UTC)

OK they may act like a lubricated funnel, but Im not sure that is their actual purpose. —The preceding unsigned comment was added by 88.110.41.242 (talk) 05:26, 18 March 2007 (UTC).

I would second that they are not necessary for sex. [Mαc Δαvιs] (How's my driving?) ❖ 06:23, 18 March 2007 (UTC)

Correct! Many men have sex yet dont have labia :) —The preceding unsigned comment was added by 88.110.177.60 (talk) 06:26, 18 March 2007 (UTC).

Not just because they are not necessary for sex, doesn't mean they don't provide a selective advantage. Remember also that there may be multiple reasons why something is a selective advantage (and there may be reasons it's a disadvantage). Nil Einne 14:07, 20 March 2007 (UTC)

[edit] Salt

Salt was valuable in the Mali empire

Why was salt so valuable in ancient times? It seems easy to make. I thought you can make it from boiling out seawater. --Shanedidona 04:15, 18 March 2007 (UTC)

Maybe because not everyone was very close to the sea? Timbuktu is a long way from the ocean. Before motorized transportation, such a journey was no easy task. Nimur 04:21, 18 March 2007 (UTC)

Salt is not trivial to produce.

Incidentally the word 'salary' derives from the Roman practice of paying soldiers with salt, or sel in French; also salinity', salient etc. Vranak

The term "worth his salt" came from Greece, when they bought slaves with salt too. --Wirbelwindヴィルヴェルヴィント (talk) 05:12, 18 March 2007 (UTC)

Here's the History of salt article that's a good read about it. --Wirbelwindヴィルヴェルヴィント (talk) 05:20, 18 March 2007 (UTC)

Another reason salt was so valuable during the middle ages, was its food connection. Food during the time tasted REAL bad, and salt was used to make it taste good enough to keep down...(no exageration here). Salt was also used to help preserve the food itself. Yes, it tasted awfull but it still was worth preserving with the salt. Salt at the time also was used as a type of "currency" or money, since it was so valuable. Zeno333 05:43, 18 March 2007 (UTC)

I have problems with your first assertion, in that people able to afford salt to use in that manner were likely pretty rich, and so could afford good-quality food. Also I would think that the amount of salt needed to disguise the taste of bad meat would be enough to ruin it anyway. Vitriol 22:46, 18 March 2007 (UTC)

Plus, everyone need salt so much, you even have an entire sense devoted to sensing salt. [Mαc Δαvιs] (How's my driving?) ❖ 06:22, 18 March 2007 (UTC)

What I said is true. See the book "Salt: A World History" as a starter. A couple of years ago there was a TV documentary stating what I said also. Zeno333 06:39, 19 March 2007 (UTC)

I concur with Zeno333; Mark Kurlansky's book covers the topic in great detail. Another additional reason for the value is military -- before motorized vehicles, sending an army or navy anywhere took a long time on foot or on a boat; salt was necessary for preserving the meat or fish provided in the rations a military force needed. This need drives the price up. --ByeByeBaby 07:45, 19 March 2007 (UTC)

But back in the past, people only got a tiny bit of salt each month unless they were very rich, which sounds very unhealthy as people nead at least a certain amount of salt

Salt is absolutely essential for life, but you only need a tiny amount. The USRDA is 1.5 - 2.3 grams per day. This is a tiny amount compared to your water, protein, fat, and carb requirements, although admittedly it's quite large when compared with most other vitamins and minerals. StuRat 19:04, 19 March 2007 (UTC)

That sounds far too small :) I cut down on my salt intake to around 6-8g per day for a few weeks and felt very ill, so I went back to my normal amount and started to get better :) Also, isn't salt a mixture of Sodium and Chlorine, so you should have 3.8-5.9g per day :] HS7 14:24, 20 March 2007 (UTC)

The usual advice in Britain is to keep your daily salt intake below 6g. If you felt ill when you reduced your salt intake to 6-8g a day, I would say either some other factor was making you ill, or you actually need to see a doctor because there is some underlying problem. People really don't need that much salt. Have some evidence-based research. Check the second from the bottom on this list of salt myths from the UK government website on salt [4]. It also has a nice little bit on the history of salt, brief and accessible for the question asker [5]. Here's some American site that says doctors recommend keeping salt levels below 2.3g a day [6], but I don't know how reliable that site is. Skittle 17:49, 20 March 2007 (UTC)

[edit] Today's Wikipedia Featured Picture...

"The summer adult has a chocolate-brown head (not black, despite the name), pale grey body, black tips to the primary wing feathers, and red bill and legs. The hood is lost in winter, leaving just dark vertical streaks." Nimur 05:46, 18 March 2007 (UTC)

MMmmmmm. :) [Mαc Δαvιs] (How's my driving?) ❖ 06:21, 18 March 2007 (UTC)

My nanna has eaten that (well, not that bird in particular). :) The line about 'dark vertical streaks' is incorrect btw - BHGs lose the brown hood in the winter, retaining only a dark patch behind each eye. --Kurt Shaped Box 09:47, 18 March 2007 (UTC)

well so much for the arlier article about not being able to hunt gulls *evil grin* ^^ Maxx4444177 17:32, 20 March 2007 (UTC)

mmmmm gulls!--Lerdthenerd 09:41, 21 March 2007 (UTC)

[edit] Shockwave theory break?

This effect operates similarly to the patterns made by sunlight on the bottom of a pool, the difference is that the light is bent at the contact point with the water while the shockwave is distorted by density variations (e.g. due to temperature variations) in the atmosphere. Variations of wind can cause a similar effect. This will disperse the shockwave at some places and focus it at others. For powerful shockwaves this can cause damage far beyond the limit where the 1 / r² law would suggest is possible. — Atmospheric focusing.

What is that about? far beyond the limit of 1/r²?? [Mαc Δαvιs] (How's my driving?) ❖ 06:21, 18 March 2007 (UTC)

Since a shockwave expands in three dimensions, its energy must decrease proportionally to the inverse of the radius from the blast squared ( $\frac{1}{r^2}$ ) - just a geometrical fact. However, according to your quote, varying conditions in its path can distort the shockwave wavefront and cause it to be stronger in some places and weaker in others - thus, in some places it can cause damage further from the blast than one would expect if it had been propagating smoothly in three dimensions. --Bmk 14:20, 18 March 2007 (UTC)

I reworded it a bit, hopefully it is more clear now. Nimur 21:05, 18 March 2007 (UTC)

[edit] Itch

Sometimes I have this itch on my sides or my back. I take allergy medicine (tried both claritin and benedryl) and neither make the itch go away. My clothes are fresh and clean, my skin isnt dry, and theres no rash or anything. I know I'm allergic to dust, but I stay away from it. What could the itch be from?

It could be many things. Consult a dermatologist or medical doctor. Nimur 19:27, 18 March 2007 (UTC)

i concur. 1) the rules say that we are not able to give medical advise and 2) we really cant help you much here without any details. also, it might possibly be a reaction to the medicine itsself, i used to take claritin but it gave me a rash something like shingles or hives. Maxx4444177 17:36, 20 March 2007 (UTC)

[edit] Testosterone types

What is the difference between testosterone, testosterone enanthate, and testosterone cypionate? I know the last two last longer in the body, but are all the testosterones the same strength at the same dosage? (like is 200mg of enanthate the same strength as 200mg of regular testosterone?) and are there any other kinds? —The preceding unsigned comment was added by 76.167.159.75 (talk) 08:51, 18 March 2007 (UTC).

As you are indirectly asking the differences of dosages of different types of testosterones and how they physiologically affect the body, I would advise you to consult a qualified physician. Also, please realize that different body types metabolize substances at separate rates, and it would not work in your best interest to mimic someone elses' dosages. XoVolition 20:41, 20 March 2007 (UTC)