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September 7

Creating a three dimensional display with diffraction patterns and coherent light

Why would it not be possible to create a three dimensional computer display by showing moving interference patterns on a display device and illumating with coherent light?
The relevent articles on holography may have ommitted to divulge the prohibiting principle on account of the conspiracy their techfuscation and my ignorance.
Many thanks, 86.132.15.29 00:59, 7 September 2007 (UTC)

One problem is that the screen needs resolution comparable to the wavelength of the light; for visible light that means billions of pixels per square inch. Another problem is that calculating the diffraction pattern is very expensive, especially with that many pixels. I don't think this is possible with current technology. There are other ways of making 3-D monitors -- see volumetric display. -- BenRG 10:30, 7 September 2007 (UTC)

Wouldn't that just be a hologram? Synthetic holographic displays have been demonstrated (very small volumes, very low resolution, very poor update rates, very big computers!) - I saw one at the SigGraph conference many years ago. It showed simple shapes (cubes, tetrahedra, teapots, etc) in a volume an inch or two on a side that updated a few times a second. It required a refrigerator-sized minicomputer to drive it and required some very fancy technology to filter the light. I believe this is what is being described in Hologram#Dynamic_holography. SteveBaker 13:37, 7 September 2007 (UTC)

How long ago was it? Computers have gotten a lot faster in recent years, so that something that would have required a Cray-2 in 1985 can be done on a desktop system today. --Carnildo 21:29, 7 September 2007 (UTC)

I would take a stab at forecasting that this technology will eventually become commonplace. As parallel processing increases and pixel densities improve it should become possible to have LASERs and computer power together on the same chip. At least it does not have to calculate at the speed of the light frequency. You could then cover the inside of walls with it to create a holographic chamber. Graeme Bartlett 22:15, 7 September 2007 (UTC)

Chickens

What are unsexed chickens?155.205.201.11 02:51, 7 September 2007 (UTC)

Chickens with their sexual organs removed. Capon is a type of unsexed (or desexed) male chicken. Tasty, tasty. HYENASTE 03:24, 7 September 2007 (UTC)

Wrong, see sexing. Cacycle 03:25, 7 September 2007 (UTC)

Could it not refer to either? HYENASTE 03:28, 7 September 2007 (UTC)

Not really. A desexed animal is one that's been rendered infertile. Unsexed is not a synonym of desexed. -- JackofOz 04:45, 7 September 2007 (UTC)

To get the answer here, unsexed chickens are chickens for which the sex is unknown. Baby hens and roosters look the same externally, but it is useful to know what is what! —Preceding unsigned comment added by Graeme Bartlett (talk • contribs) 07:09, 7 September 2007 (UTC)

...so that they know which fluffy little chicks to gas. :-( --Shantavira| 07:36, 7 September 2007 (UTC)

Luxury! --Sean 14:48, 7 September 2007 (UTC)

Also see the excellently-named article Chick sexing. --Sean 14:48, 7 September 2007 (UTC)

And its not as easy as it looks. It take a lot of experience to be a fest sexer. Mrdeath5493 18:29, 8 September 2007 (UTC)

iPod playlist randomization

Whenever I set my iPod to shuffle my entire playlsit, the first song is almost always a song I really, really like. Is this algorithm truly random, or does it favor songs that have received a high number of plays in the past? --The Fat Man Who Never Came Back 03:15, 7 September 2007 (UTC)

Without really giving you an answer, they claim the playlist is random, but I too have noticed there seems to be preference for playing regularly played, and therefore presumably favoured, songs. I wonder if it isn't a 'smart' algorithm that in fact does factor in the play count (although presumably if that was the case, over time it would become more and more biased by the ever increasing play count on those songs, unless that's factored in too). --jjron 07:22, 7 September 2007 (UTC)

I have no idea about the design of Apple software but are you sure this isn't just a case of observer bias. You tend to remember when the first song is one you really like more then when it isn't Nil Einne 11:20, 7 September 2007 (UTC)

No, I tested it several times. Believe me I have some real crap on my iPod, and it consistently chose a good song first.--The Fat Man Who Never Came Back 11:43, 7 September 2007 (UTC)

Newsweek and The Wall Street Journal weigh in. (many others available by searching ipod random function). --LarryMac | Talk 12:02, 7 September 2007 (UTC)

If you are rating your library's songs, iTunes has an "Play higher rated songs more often" check mark in the Party Shuffle mode. Are you sure that isn't selected? The iPod has a similar feature as well. Titoxd 18:19, 7 September 2007 (UTC)

Moon Phases

I was asked to chart the 16 phases of the moon. I have researched and only found 8. Do you know the names and have the charts to the 16 phases of the moon? 68.104.172.14 05:07, 7 September 2007 (UTC)

Lunar phase indeed lists eight. Could the request be associated with Hindu tradition? Googling for moon "16 phases" suggests Hindus count 16 phases or "kalas". The first two are called Amrita and Manada (type those into google if that's what you are looking for.) Weregerbil 06:07, 7 September 2007 (UTC)

....also called the sixteen "digits" of the moon.--Shantavira| 07:44, 7 September 2007 (UTC)

It's not really a scientific matter. As far as science is concerned, moon 'phases' are merely a convenience for humans - there aren't really discrete phases in reality - there is a continuously variable amount of shadow and light on the surface of the moon as viewed from the earth. The choice of 4, 8, 16 or a hundred names for various amounts of shadow is a purely linguistic matter. So the number of phases may vary from culture to culture, from language to language. Perhaps you should ask this on the language reference desk? SteveBaker 13:28, 7 September 2007 (UTC)

Elastic Behaviour in Polymers

I have a challenging question which I would like help on.

I am interested in polymer materials that increase in strain over time. For example, this material is one which is initially of 20mm in length and after it is left alone in normal conditions for say five hours its length increases to 22mm.

I have heard of anelastic materials which exhibit this sort of behaviour, but I do not know for certain. I have tried to research this behaviour online, but I have not found much useful information. It would be very helpful if someone could provide me with a list of materials that exhibit this type of behaviour (I am after specific materials e.g. Polyvinyl chloride). Thank you very much. —Preceding unsigned comment added by Total revolt (talk • contribs) 05:21, 7 September 2007 (UTC)

I would look at Hygroscopic materials - these absorb moisture from the air and thereby get larger. I don't know of a polymer that works like that - but if you are only seeking a 10% increase then maybe you could mix sodium hydroxide or calcium chloride (both strongly hygroscopic) into a regular polymer - or perhaps find a chemical varient of a polymer that would have these kinds of substances bound as side-chains? Dunno - we need a chemist. Someone here will know. SteveBaker 13:24, 7 September 2007 (UTC)

The question itself is confusing: how does the change of length relate to the idea of strain? That is, does the material become elongated while just sitting on the table, or is it under tension and gradually elongates, or...? Is it getting larger in volume (swelling lengthwise) or just stretching and narrowing (deforming like a piece of rubber)? There are lots of polymers that absorb water (polyaspartate is a good one), not sure which ones swell (and which of those swell directionally, as the question seems to imply?) vs which just "fill in spaces" in the existing matrix. DMacks 14:32, 7 September 2007 (UTC)

I am interested in a material that becomes elongated while just sitting on the table. This could be caused by initiated by compressing it beforehand or adding a certain substance to it. Ideally, the material is not getting larger in volume, just increasing in length. User:Total Revolt —Preceding unsigned comment added by Total revolt (talk • contribs) 03:28, 8 September 2007 (UTC)

Entomologist needed; weird bug in my room!

Okay, there's this weird bug hanging on my window blinds and I really want to know what it is:

• It flies.
• Its pretty big. Counting its wings folded behind it its like 2 inches long, though its body is more like 1 inch
• It has really long back legs and short front legs.
• Its green.
• I'm not sure what its doing. At first I thought it was eating some of the dirt on my window blinds (don't ask), but I think its just chilling. It keeps pulling its back legs up and rubbing them.
• I live in Northern California.

What is this bug? Atropos 05:24, 7 September 2007 (UTC)

Any chance you can get a picture of it? Someguy1221 06:05, 7 September 2007 (UTC)

A locust? — Kieff | Talk 06:15, 7 September 2007 (UTC)

It looks like a locust, but its legs are all much more thin compared to its body than any of the pics shown. Atropos 06:38, 7 September 2007 (UTC)

Acrida cinerea or any of its cousins? -- Sundar 06:46, 7 September 2007 (UTC)

Sounds like another species of grasshopper other than your usual locusts. The green colouring, size, and behaviour (e.g., rubbing its legs) ring true with many grasshoppers I've seen. --jjron 07:10, 7 September 2007 (UTC)

I think it's probably a cricket, does it look like this? ]Richard Avery 07:13, 7 September 2007 (UTC)

It's not a Praying mantis then? Nil Einne 10:58, 7 September 2007 (UTC)

It could be a Katydid. -- JSBillings 12:53, 7 September 2007 (UTC)

I found a weird bugger in my room once. It was my roommate. —Bromskloss 13:46, 7 September 2007 (UTC)

Well at least it wasn't mating (or buggering) Nil Einne 14:32, 7 September 2007 (UTC)

Buggers? Lanfear's Bane 15:46, 7 September 2007 (UTC)

It looks a lot like the cricket and catydid pictures, but its legs are a lot thinner and its body is only about half as long as its wings, while those all have the long portion attached to the end of the body. Also, its head looks a bit like a praying mantis. It really reminded me of a cross between a cricket (though the crickets I'm familiar with are brown) and a mantis.

Its probably just some odd species of cricket. Atropos 23:42, 7 September 2007 (UTC)

From your description I'm pretty sure that the insect was a katydid (Family Tettigoniidae). The Bush Katydid (Scudderia furcata) is very common in California--I've seen it or a similar species many times (I live in central California). Try doing a image search in google using the keyword Scudderia and see what you think. Katydids neither bite nor sting, but they can damage plants by eating the leaves. They have a clicking song.--Eriastrum 17:45, 8 September 2007 (UTC)

Thankyou! I think that's definitely what it was. All of you rule. Atropos 19:58, 8 September 2007 (UTC)

Pathogens in flower vase water??

In the UK some hospitals are prohibiting cut flowers in wards and patient rooms because there is a perceived risk from organisms that may grow in the water of the vases and if the water is spilled this could constitute an infection risk to patients - and presumably staff.

My question is - does any biologist or microbiologist out there, or indeed anyone, have any sourced information about the incidence of organisms that could cause infections in humans? We all know the water goes off and smells and maybe bacteria grow in the water but just how dangerous is it to human health. Richard Avery 07:19, 7 September 2007 (UTC)

Bear in mind from the case you mention it sounds like this isn't just water but water containing the stems of cut flowers, which are potentially good sources of nutrients and bacteria. Also in hospitals many people are somewhat immuno-compromised and are much more susceptible to infection then the average person. The hospital would be much more worried about the risks to patients then they would be to staff Nil Einne 10:56, 7 September 2007 (UTC)

I did a few searches and came up with some links but there are more. . From what I can tell there is definitely some concern about types and level of growth of bacteria in flower vases. But there has been no evidence for any infections linked to these sourced. However in strongly immunocompromised patients, e.g. ICU, burns units it's still recommended to remove such risks. In more normal wards I think most hospitals wouldn't be so concerned but you ideally should still treat the water with disinfectants like hypochlorite to be safe. Nil Einne 11:14, 7 September 2007 (UTC)

Remember this is a hospital - there are open wounds and people with compromised immune systems - so even the normal bacteria that's in soil (and therefore on these plants) could be a problem. It's not hard to imagine a splash of water as flowers are changed - or an accidental spill getting dirty water onto a dressing and thereby soaking into a wound. It would be nice to know whether they are banning them because of a 'perceived' risk - or because someone has done actual studies to make it an 'known' risk? If it's the former - then yeah - maybe it's an overreaction, but if it's the latter, perhaps not. There are plenty of things in soil (and therefore, eventually in the water of cut flowers) that can be harmful to humans. Amoebae grow in soil and thrive in dirty water. They can form 'cysts' (like 'spores' in plants) that let them blow around in the air as the water dries up. Our article on the amoeba lists five species that are hazardous to humans. Ever heard of amoebic dysentery? Obviously that's just one thing that might be in the soil that could do this...I'm sure there are any number of other bugs. Remember - commercial plants are probably grown in composted animal manure. Now - are those actually real problems that cause an unacceptable risk to patients? I don't know - but it wouldn't surprise me to find that the concern of the hospital is warranted. What I bet they have NOT studied is the benefit to patients of having flowers in terms of making them happier, perhaps relieving stress, reminding them of the person who gave the flowers - there is a lot going on with the 'placebo' effect where the mind drives recovery and who knows what effect flowers might have on that. SteveBaker 13:15, 7 September 2007 (UTC)

One example is Legionella bacteria that cause Legionaire's disease. Cases of infection are linked with bacteria in the ventilation system, not flower vases. However I suppose it's possible. Flyguy649 _contribs 15:56, 7 September 2007 (UTC)

OK, thanks for your comments guys, the two links make interesting reading and indeed show that some tricky bugs do grow there but the jury is out on their actual effect. It also seems that the anxiety could be overcome with the addition of hydrogen peroxide which disinfects the water and then the patients could be safely cheered up. Richard Avery 15:31, 10 September 2007 (UTC)

Identify this waterborne organism

I noticed several worms (looking like young earth worms) constantly pulsating (most of them with one end inside some tubular "mud" structure) in rain water collected in a roadside of a tree-covered campus in Bangalore. Please look at the two videos below and help identify the organism.

Commented out problematic videos SteveBaker 03:40, 10 September 2007 (UTC)

Excuse the poor resolution and glare. -- Sundar 09:31, 7 September 2007 (UTC)

I couldn't view the videos, and I'm not familiar with the fauna of India, but from the still images those look like they could be redworms.

Earthworms can't tolerate being submerged in water -- they drown. I'm guessing that the "pulsating" motion you describe is the worm's feeble attempt (using musculature optimized for burrowing through soil) to swim away. (But this is pure speculation, and without having viewed the video I could be very wrong.) —Steve Summit (talk) 13:27, 8 September 2007 (UTC)

Steve, thanks for your suggestion. It doesn't look like redworms much. A lot of them are only slightly bigger than mosquito larvae and the bigger ones are about twice the size. The pulsating motion I described was seen in every individual organism (worm) and appeared to be characteristic of them (similar to mosquito larvae) rather than a "feeble attempt." They seem to be adapted for those conditions. I'll try to take a higher resolution still photograph on Monday and upload. -- Sundar 15:28, 8 September 2007 (UTC)

They look like tubifex worms to me. Take a look at our article Tubifex tubifex and also do an image search on Google using the key word tubifex.--Eriastrum 17:54, 8 September 2007 (UTC)

Eriastrum, based on image search for "tubifex", I think you're right. Thanks for the information. This was happening when I saw. -- Sundar 05:37, 9 September 2007 (UTC)

Can bamboo be grafted while growing?

I know trees can be grafted either within the same species, or even using parts of the same tree (crossing branches together) this is most frequently in Arborsculpture. DOes anyone know of a similar process for bamboo? Or think that it is possible?

Thanks! —Preceding unsigned comment added by 128.113.36.239 (talk) 13:21, 7 September 2007 (UTC)

I doubt it. Bamboo is a species of true grass and one of the odd things about true grasses is that they grow at the base of the plant rather than at the tops (as with - for example - most trees and shrubs). This is because grazing animals eat the tips of grasses and if that was where the growth was happening then they'd be in trouble. So it may well be that because of this, conventional grafting might not work - but finding definite information about that might be tough. SteveBaker 13:55, 7 September 2007 (UTC)

Grafting of bamboo was covered in "The Grafting of Large Monocotyledonous Plants" by Thomas J. Muzik and Carl D. La Rue in the November 28, 1952 edition of Science. If you can somehow get a copy of that article, you can see how they did it. -- kainaw™ 14:04, 7 September 2007 (UTC)

It shouldn't really be that hard. Both and should have it and many academic libraries should have access to it (albeit they may require you be a member although I note that Jstor says "Our license agreement with libraries allows for use of the archive by anyone present in the library, whether or not they are affiliated with that institution"). Most decent academic libraries would probably still have the paper journal too, albeit perhaps in storage (i.e. it may not be accesible to non members). You could take a look at your local public libraries and academic libraries and see if they offer what you need. Even if your local library doesn't have the journal it could potentially get it via the interloan system for a fee. Or if you're desperate you can buy it for US$10 Nil Einne 14:30, 7 September 2007 (UTC)

Why do spiders hang upside down in their webs?

Why do they wait in a head-downward position? Why not head up? Or any other direction? —Preceding unsigned comment added by Dominus (talk • contribs) 13:40, 7 September 2007 (UTC)

Well, I would guess that they want to be able to get to any point on their webs really quickly - and downhill is faster than uphill. So they want to be at the top of the web - and in order to see what's going on - facing downwards makes sense. Also, they spin silk from their hind-end, so if they need to escape on a thread in the wind then attaching the line from their rear end and sailing downwards would be the fastest thing. But that's a guess - it's hard to know for sure. SteveBaker 13:49, 7 September 2007 (UTC)

Your guesses are no good. Spiders do not wait at the top of the web; they wait in the middle. -- Dominus 14:09, 7 September 2007 (UTC)

His second guess about spinning a thread fast for escape is still a possibility. Would it force more blood to the brain so they think a little sharper? This is a completely random guess on my part :p Capuchin 14:16, 7 September 2007 (UTC)

My guess is that it has to do with staring at the bright sky all day long. Not good for the eyes and all that. If I had to hang in a web all day long, I'd probably look down too. ;-P --24.147.86.187 14:25, 7 September 2007 (UTC)

I don't know if there is a well understood reason. It could be a left-over behavior from when spiders hung from a single thread, it could be related to markings on the abdomen to warn off predators, for orb-weaver spiders, it might be related to how they construct their webs. -- JSBillings 16:03, 7 September 2007 (UTC)

Since humans, as most animals do, hold their heads up, you assume that that's normal. Spiders might wonder why all the other animals are upside down. Maybe they figured out that that's because they always walk on the ground - in which case spiders also have their heads up. But in the web there is no need for that. Then again, that doesn't explain why they prefer the heads down position over others. One possibility is that other animals will, like you, consider that an abnormal position and therefore be less inclined to think that what they see is an animal. DirkvdM 08:23, 8 September 2007 (UTC)

Maybe what someone should do is invent an upside-down world wide web, then we could all hang around upside down.  :) -- JackofOz 13:47, 8 September 2007 (UTC)

You're asking for this - don't you Aussies already do that? DirkvdM 17:47, 8 September 2007 (UTC)

Certainly not. -- JackofOz 01:18, 10 September 2007 (UTC)

My guess. Their spinners are in the rear abdomen. Unlike spiderman, they cannot shoot their webs so they attach it and use their body weight as tension. This implies head down. --DHeyward 06:32, 11 September 2007 (UTC)

I was able to speak with Jonathan Coddington, a research entomologist with the Smithsonian Institution, and an expert on spiders. His answer was that the spider wants to attack in a downwards direction to get a speed and force assist from gravity. For this reason spiders construct their webs so that the lower part is most likely to catch prey, and then waid above this part, pointing downwards, for quick attack.

He said it had nothing to do with vision, and that spiders are nearly blind. -- Dominus 15:10, 11 September 2007 (UTC)

All those eyes, and still nearly blind? The spider article says "Their eyes are single lenses rather than compound eyes, ranging from simple light/dark-receptors to eyes rivaling those of a pigeon (some jumping spiders). in some cave species, there are no eyes at all. Several families of hunting spiders, such as jumping spiders and wolf spiders, have fair to excellent vision. However, most spiders that lurk on flowers, webs, and other fixed locations waiting for prey tend to have very poor eyesight". So it varies. DirkvdM 18:30, 11 September 2007 (UTC)

A theory for the origin and purpose of dark matter and energy. Could it be true?

This is a theory for the origin and purpose of dark matter and energy. I just thought of this and i'm not a physics student. I just want to know if there is a chance that this could be true or if others have already thought of it.

We basically know that our universe is expanding and it will keep expanding until all matter tears itself apart (The Big Rip) 20 billion years from now. I think the dark matter and energy around us now is a remnant of an old universe that existed before the Big Bang that created our universe. It's the remains of a previous Big Rip.

What’s the point of dark matter / energy? Dark energy drives the universe's expansion. I think dark matter slows it down. Right now there's more dark energy than dark matter in the universe - that is why it's expanding. I think that after each Big Rip, the concentration of dark matter relative to dark energy increases. This increase slows down the expansion of the next universe and gives it a longer life. This cyclical process will keep happening until the increased concentration of dark matter vs. dark energy nullifies the expansion. Then that universe should exist forever (no more Big Rips) or at least a much longer time than usual. Also, it will be more tightly packed by cosmic standards and bodies of matter will be closer together. I think dark matter and dark energy act as a balance scale for gravity and expansion. —Preceding unsigned comment added by 67.110.174.2 (talk) 15:54, 7 September 2007 (UTC)

For this theory to be scientifically sound, you will need some kind of observable evidence which backs up your prediction. For that to be effective, you will probably have to quantify your assumptions with some mathematical rigor. To be sure that you haven't overlooked some detail, you should review the entire body of established literature. This process will take some time and require a lot of peripheral understanding of physics. The typical approach is to be a physics student; this will enable you to make informed judgements about the present state of the discipline, and eventually contribute to the body of knowledge. What you have provided here is sort of vague and may even border on unfalsifiability. Good luck! Nimur 18:02, 7 September 2007 (UTC)

Unfortunately, we don't really know enough about dark energy to make any clear conclusions about what it is. Depending on the nature of dark energy and its equation of state, there may or may not be a Big Rip. We hope to catch a first glimpse of the dark energy equation of state parameter w within the next 10 years or so. As for dark matter, we expect to be able to understand it in terms of heavy particles that are simply difficult to detect because they don't have electromagnetic or strong force interactions. A lot of scientists are hoping that LHC will be able to produce particles like this.

Your idea reminds me a lot of the ekpyrotic cosmology, which is a modern form of a cyclic universe. You might also enjoy reading about the bubble universe theory / chaotic inflation. --Reuben 19:01, 7 September 2007 (UTC)

All of the cosomologies that rely on a big-bang happening more than once (with big rips or big crunches or whatever) are problematic and unfalsifiable. The problem is that when all of everything is within the singularity at the very start of the big bang, there is no information contained within it. This means that absolutely no information about the preceeding universe (if indeed there was one) can make it's way into this one. Everything that may have proceeded the big bang is irrevocably lost. Given no information about the preceeding universe, we are unable to either prove or falsify it's existance. So, yeah - it could be that the universe is cyclic - but there is nothing we can say either way about that. Feel free to believe in a cyclic universe - but you can no more prove it than you can prove that Santa Clause brought it in his sack. It's rather pointless to spend time thinking about it. SteveBaker 20:43, 7 September 2007 (UTC)

I've seen versions of string theory in which the universe expands and collapses over and over, and each time the fundamental force constants and the allowable particles change randomly. It was a way of making the existence of life not anthropic, but probabilistically inevitable. Although it still suffers from the issues Steve gave, the whole...not being able to test it thing. Someguy1221 21:22, 7 September 2007 (UTC)

The ekpyrotic model doesn't have an initial singularity, and predicts a characteristic spectrum of gravitational waves. --Reuben 21:56, 7 September 2007 (UTC)

BF Skinner

Was his mother really a crack whore as the article about him suggests? I'd never heard that. —Preceding unsigned comment added by 198.150.162.65 (talk) 19:38, 7 September 2007 (UTC)

That was vandalism, now removed. Someguy1221 19:42, 7 September 2007 (UTC)

I knew Mother Skinner, and she was a marginal whore at best. --Sean 21:43, 7 September 2007 (UTC)

Did she own the original Skinner box? Edison 00:09, 8 September 2007 (UTC)

Despite Skinner's best efforts with the old dear, he found you can lead a whore to culture, but you can't make her think. Rockpocket 00:47, 8 September 2007 (UTC)

I've reported this user to Misplaced Pages:Administrators' noticeboard/Punsters asking for lifelong bans from editing Misplaced Pages ---Sluzzelin talk 02:31, 8 September 2007 (UTC)

Its a fair cop, guv'! Rockpocket 04:21, 8 September 2007 (UTC)

How much plutonium

How much plutonium has been produced or exists on earth today? —Preceding unsigned comment added by 88.109.213.2 (talk) 22:29, 7 September 2007 (UTC)

Exact numbers will not be available, because production amounts of plutonium are considered secret by all nations that produce plutonium (knowing production numbers or even production capability gives you the tools needed to estimate a stockpile size very accurately). But maybe we can get an order-of-magnitude estimate by thinking about how many nuclear weapons are on the earth today, most of which use plutonium cores (because it is very efficient, and easier to produce than enriched uranium for a large nuclear power). According to List of states with nuclear weapons, there are about 20,000 nuclear weapons in the world at the moment. I would guess that on average they each have at least 10 kg of plutonium in them. I have no idea how much plutonium would be in the sparkplug of a Teller-Ulam design, and can find nothing which would give much of a hint in any of the related articles (or a few other sites I checked). But okay, that puts a minimum of around 200 tonnes of plutonium around today and refined for weapons purposes. It does not include plutonium produced incidentally as part of nuclear reactor operations, which is probably quite a lot, but most of it is never separated from the fission products and is just deposited as nuclear waste (at least it is in the US—I don't know if other countries do reprocessing). --24.147.86.187 22:55, 7 September 2007 (UTC)

Oh, I just checked plutonium, and it says there is an estimated "300,000 kg accumulated worldwide". So 200 tonnes as a guess was the right order of magnitude, but still about 100 tonnes short — probably because nations keep more plutonium reserves than they use in weapons themselves. Note, by the way, that the amount produced is probably almost identically to the amount used on Earth today, since it has a relatively long half life (it is a weak alpha emitter). --24.147.86.187 22:58, 7 September 2007 (UTC)

(EC) The book Plutonium and Highly Enriched Uranium 1996: World Inventories, Capabilities and Policies, by David Albright, et al., says that in 1996 there were 1160 tonnes of plutonium and 1770 tonnes of HEU in worldwide inventories (page 396). It's probably similar today. --Sean 23:11, 7 September 2007 (UTC)

How large of a cube would that be, if it were all piled together (not that I would for a microsecond consider doing that)? Edison 00:11, 8 September 2007 (UTC)

Well, it has a density of 19.816  g·cm... soooo.... umm... in any case, it is pretty dense stuff. --24.147.86.187 00:24, 8 September 2007 (UTC)

Uh, I don't think you could put it all together in a cube (critical mass might become an issue at some point along the line). --SB_Johnny | 00:58, 8 September 2007 (UTC)

You could, but you'd have to do it very, very quickly, and then run away really, really fast. :) Anyway, I calculate that it would be a cube 8.4 meters on the side. --Sean 01:23, 8 September 2007 (UTC)

Please note that the Reference Desks cannot offer professional advice. You should consult a qualified mad scientist. Gandalf61 13:39, 8 September 2007 (UTC)

-- Yo. -- Nimur 16:46, 8 September 2007 (UTC)

Global Warming Real Estate Speculations

Much of the news on Global Warming is in the negative; Would the warming up of the planet make Russia's Tundra area prime real estate? And what about 1918 The Year Without A Summer? --i am the kwisatz haderach 23:32, 7 September 2007 (UTC)

Perhaps, if you like your real estate to have an atmosphere containing "billions of tons of methane gas". See also Effects of global warming for the environmental payoff for a nice duplex in the Siberian peat bogs. Rockpocket 00:59, 8 September 2007 (UTC)

If you want to speculate on warming, don't buy tundra. The effects of warming on tundra are not generally positive. Instead, look for land that will become seacoast due to sea level rise. Look for steep terrain that is just inland of current low-lying areas. make sure you purchase land that extends from just above the current sea level to at least a few meters above the current sea level. Your best bet is to look at very low areas, and to turn your investment over about once every ten years as the sea level rises. In South Carolina, you will be moving west at about one mile per decade, while the traditional land owners will move more slowly. -Arch dude 02:48, 8 September 2007 (UTC)

The bad thing about global warming is not that the new climate (once it has stabilised to one) is worse. It's the change itself that's the problem. Life is used to a certain climate and any change will make it less adapted, possibly resulting is mass extinction. The worst one, the Permian–Triassic extinction event, which killed about 2/3 of species on Earth, is speculated to have been caused by an initial rise in temperature of about 5 C, roughly what is expected to happen in the next few centuries. Except that it took a whole lot longer then. A few centuries is the blink of an eye in evolutionary terms. So if a similar change over (tens of) thousands of years had such a dramatic effect, what will the effect be if it happens in such a short time span? In human terms, things might not seem so bad, because we are highly adaptable and can simply shift our population centres. In theory, that is - a shift across borders would likely result in war. And then of course there's the dying of other species, because we depend on them in many ways, mostly indirectly, but also directly because the traditional agriculture will not be sufficiently adapted to the new climate (if it settles to one, that is). Again, humans can adapt, but, again, it's the transition itself that is the problem. The search for a more adapted agriculture will take some time (decades, centuries?), during which there will be less food. And if this happens worldwide, there will be no surpluses elsewhere to compensate.

To clarify, what I meant to say was that the best that can happen to a region is not a change to a 'better' climate, but no change at all. There is no such thing as a better climate. Actually, climate means predictable weather and when it changes, that means there will be less climate, however odd that may sound. And farmers are highly dependent on the predictability of the seasons. Stupid thing is, we're building up excessive luxury at the expense of the very basis of our livelihood, namely food (and water, for that matter). Our descendants will be pretty pissed off with us. DirkvdM 08:52, 8 September 2007 (UTC)

What does any of that have to do with real estate speculation? Perhaps buying coastal and lake-front properties in areas that are currently completely ice-locked would work out well. (Remember to account for changes in sea-level.) APL 04:58, 10 September 2007 (UTC)

No appreciable effects will happen in your lifetime. Better to buy bonds than to speculate on GW real estate. --DHeyward 07:54, 10 September 2007 (UTC)

There are certainly some places you don't want to buy right now. In Alaska and Siberia, the permafrost is melting, turning areas that used to be rock-hard soil into swamp. True, Florida isn't likely to vanish in your lifetime, but there are areas that will be affected, and those tend to be in the extreme north and south. --Carnildo 21:12, 10 September 2007 (UTC)

The effects on agriculture will be worldwide, and with our food patterns depending for a large part on international trade, the countries that rely on that most will suffer most. Some countries may get lucky, say if they have invested in foodcrops that don't really belong in that climate but coincidentally belong in the new climate (insofar as one can call it that), but that's extremely unlikely.

In answer to APL's question about the relevance of my remark, I guess I wasn't clear enough; climate change will have negative consequences everywhere, even if it seems that one aspect is positive. The negative sides will likely prevail, wherever you buy your land. Maybe the best bet would be New Zealand, because it is likely to suffer least, so people will start to move there. Until the Kiwis will stop the flow, in which case they might also find themselves at war. DirkvdM 06:06, 11 September 2007 (UTC)

Some countries WILL get lucky, some nations WILL prosper from global warming. Some nations WILL be unlucky, some WILL face some terrible unstable/difficult times. It continues to astound me that so many people think that the scientific evidence is justification for predicting a terrible future, when the future of people is dependent not on science but on political and social policy. Whatever climate change brings making predictions about how the world's population will cope is extremely difficult. In the world today we have people living in virtual every climate currently offered to society, we have people living at every imaginable nutrition level from virtually-none to a sheer abundance of food. We have people living eco-friendly lives right up to people living extremely wasteful (energy/produce wise) lives. To predict the effect global warming will have on an infinitely varied number of circumstances is borderline stupid (if it weren't for the need for media outlets/planners to try predict such futures). ny156uk 23:16, 11 September 2007 (UTC)

Can you name a country that would get lucky in the balance? I can't think of one (apart from maybe New Zealand). You mention that people cope all over the world, but as you also point out that that coping is sometimes on a bare minimum or less. And that's in a fairly stable climate that people have evolved to live with. But even in that stable climate failing crops have led to mass starvation, such as the Sahel drought in the seventies. But now the climate is changing as well, so any catastrophies we are used to will only get aggravated. Lower crop yields in a poor country that is already only just 'hanging in there' will result in starvation. Politics can't change that. Except for worldwide coordinated politics. Which is being attempted, but the results come excruciatingly slow, if at all. DirkvdM 18:56, 13 September 2007 (UTC)

September 8

adrenal insufficiency

What are the signs and symptoms of adrenal insufficiency and how do you treat it? —Preceding unsigned comment added by 72.69.222.19 (talk) 02:03, 8 September 2007 (UTC)

If this is for yourself, you should see a doctor. If this is your med-school homework, a doctor should C you. --Sean 02:12, 8 September 2007 (UTC)

If this is med-school homework, please give up on your goal of becoming a doctor Nil Einne 15:42, 8 September 2007 (UTC)

That's a pretty ridiculous suggestion. See your talk page. --David Iberri (talk) 20:12, 8 September 2007 (UTC)

I was simply pointing out that a medical student, for that matter any student who is for whatever reason unable to do their own searches is not going to get very far... I would strongly suggest that such a student seek help and find out how to search for stuff themselves or alternatively perhaps being a student isn't their path in life. I admit I'm not an expert but I was a student not long ago and I can say from my experience if you're unable to search for something as simple as adrenal insufficiency you're going to have major problems as you progress Nil Einne 08:15, 9 September 2007 (UTC)

It depends on the etiology. See adrenal insufficiency for some details. --David Iberri (talk) 02:26, 8 September 2007 (UTC)

(ec) Ever noticed the search box on the left hand side of your screen? Typing adrenal insufficiency would direct you to Adrenal insufficiency the from there (box, top right) you will find plenty of links that will help you find the answers to your question. Rockpocket 02:27, 8 September 2007 (UTC)

Identifying slug like creature

This is a photo of a slug like creature taken in the Redwoods area of Northern California. Can anyone identify it (or point me to the relevant slug identifying desk)? Cheers. --Roisterer 05:19, 8 September 2007 (UTC)

I'm pretty sure it's a Pacific banana slug (Ariolimax columbianus). They can be huge! -- Flyguy649 _contribs 05:22, 8 September 2007 (UTC)

Thanks. As it turns out, the Pacific Banana Slug has more than enough images anyway. I was hoping I had snapped an image of an extremely rare slug. --Roisterer 05:29, 8 September 2007 (UTC)

You can occasionally see a particularly large one supporting the University of California, Santa Cruz at sports events. Rockpocket 05:57, 8 September 2007 (UTC)

Your picture looks clearer than most of the pictures in the article, so it might be useful anyway. Skittle 11:24, 8 September 2007 (UTC)

yeah, I think it is clearer than the current images we have so I suggest you move it to a better name and use it in the infobox of the article. Jeltz talk 13:39, 8 September 2007 (UTC)

Yeah, they aren't rare, but they are much loved. As a child in Northern California they took us on field trips to the Redwoods and one of the "activities" was to kiss a banana slug. --24.147.86.187 12:30, 8 September 2007 (UTC)

Kiss them? Why? Do they secrete psychotropic substances? Who was running these field trips?--The Fat Man Who Never Came Back 14:52, 8 September 2007 (UTC)

What our anon friend fails to mention, I suspect, was that she was born in the late 50s and the Redwoods were in The Haight Rockpocket 08:11, 10 September 2007 (UTC)

Nice photo! I definitely encourage you to work it into article space somewhere. Also note that despite the name, these guys taste nothing like a banana. Friday (talk) 16:18, 10 September 2007 (UTC)

When the slime comes into contact with a moist surface, it produces an anasthetic which causes the membranes to go numb., according to the article. Lanfear's Bane 15:36, 14 September 2007 (UTC)

mobiles- radio access

Why do the mobiles can't access radio or F.M.stations without any headsets. If we try to do that..it always displays "connect an enhancement" or "insert an earphone"...but why this was so? Temuzion 11:06, 8 September 2007 (UTC)

The earphone cable acts as an antenna to pick up the radio signal I think — Matt Eason 12:03, 8 September 2007 (UTC)

But why couldn't they just put an internal antenna in? --antilived 00:16, 9 September 2007 (UTC)

I don't know if the phones really work as an antenna. It is a good explanation, however. I just want to say that an antenna that works on the FM frequency range should have a length of about 1.5 m. That's why there isn't an internal FM antenna on the mobile devices. 84.91.226.18 22:31, 9 September 2007 (UTC)

This explanation is also nice...but you said it needs to be 1.5 mts length..if that length need not to be straight...then why can't they put it in a folded way in that phone? Temuzion 05:09, 10 September 2007 (UTC)

For a half-wave antenna you would need 1.5 metres long antenna for 100Mhz, but half-wave dipole is not the only type there is out there... --antilived 08:25, 10 September 2007 (UTC)

Brain IQ

Are their real real ways to increase brain IQ to a genius for example??if their is what are they —Preceding unsigned comment added by 212.107.116.246 (talk) 12:33, 8 September 2007 (UTC)

In theory, your IQ doesn't change through your life - in practice the definition of 'IQ' and the way it's tested is not perfect. But if you just want to know whether you can make yourself smarter - there are no short cuts. Read lots of books - study subjects that interest you - exercise your brain, do things that are hard. Writing for Misplaced Pages is a great way to do that. Research subjects - get to be expert in them - write articles about them. SteveBaker 14:15, 8 September 2007 (UTC)

You can certainly increase your IQ score by practising on books of IQ tests and books of lateral thinking questions and cryptic crosswords. Studying stuff like maths and logic will also help you to think more clearly. Whether this increases your actual intelligence is debatable.--Shantavira| 15:15, 8 September 2007 (UTC)

Exactly. As I mentioned in an earlier question it's highly questionable how much merit IQ tests have since it's well established that you can increase your IQ score by practicising. If your definition of intelligence is "how well you perform in IQ tests" then by definition you are increasing your IQ. But this seems a pretty sillt definition to me even if it appears to be a definition commonly used by the media (effectively). However if you consider intelligence an inate ability which can't be increased then clearly all you've shown is that IQ tests are not an excellent measure of intelligence. From a academic standpoint, what intelligence is is a hotly debated topic. Clearly IQ tests are measuring something and it appears to be at least partially inate but as I've already mentioned is not completely. It does appear to be a predictor of how well people will perform at certain real world tasks. In any case, whether you it really makes sense to sum up 'intelligence' into one metric is a different issue altogether. Also whether you can truly seperate the inate from the learnt is another rather complicated issue. Considering things from a real world view you should first ask yourself what you want to achieve. If your goal is to get into MENSA then sure improving your IQ score may be useful. If your goal is to better yourself and perhaps improve your job prospects and/or eventual salary then you'll likely find there are more sensible ways to do this. Nil Einne 15:41, 8 September 2007 (UTC)

The apparent circularity in the definition of "IQ" is real and fairly widely acknowledged. (It is not just a media misconception.) In fact, none other than Alfred Binet (who invented the IQ test) was once asked what "IQ" was, and he answered, with an almost perfectly straight face, "It's what my test measures." —Steve Summit (talk) 15:50, 8 September 2007 (UTC)

Yes but note there's a big difference between IQ and intelligence. IQ is what the IQ test measures. IQ is supposed be a measure of intelligence too but how good it is, is an open question. As I mentioned there is big debate about what intelligence is but for many people it's an important thing. So there's a big difference in saying women on average score lower on IQ tests and saying women are less intelligent on average then men. The first appears to be mostly factual (the reasons are debated and as I mentioned earlier I've heard before the original IQ tests AFAIK had the medians for males and females separate so each was 100) the second is unproven and likely to be considered offensive. How useful the IQ is in general (whatever it measures) is another question altogether. The thing is the media often confuse the difference between IQ and intelligence even though these are very different concepts. Nil Einne 10:03, 9 September 2007 (UTC)

Agreed on all points. Anyone who equates "IQ" with "intelligence" is committing a rather grave intellectual sin. The test's inventor didn't equate the two, and nobody else should, either. —Steve Summit (talk) 13:06, 9 September 2007 (UTC)

Intelligence is a function of many things. Me, I'd say some of the important ones are:

1. Memory. Intelligent people have a fantastic memory, and can readily remember old facts which bear on a current problem.
2. Logical thinking. Intelligent people reject emotional arguments and guesswork, and insist on accurate, repeatable, scientifically-valid answers.
3. Making connections. Intelligent people notice connections between seemingly-disparate facts and events, and build on these connections to form new knowledge.
4. Seeing patterns. Intelligent people notice when a new problem is "just like" an old one, so that they can use the solution to the old problem to guide the solution of the new. (I put "just like" in quotes because sometimes the similarity can be startlingly oblique -- but it's there, and if you can see it, it helps.)
5. Discipline. Intelligent people are driven in their search for truth. They're willing to work much harder at it, and at avoiding the fallacies and intellectual shortcuts which lead to false knowledge.
6. Thirst for knowledge. Intelligent people love learning new things. Their brains suck them up automatically; they don't even necessarily have to work at it.
7. Recognition of problems. Sometimes, the hardest part of solving a problem is just recognizing that it is a problem that's potentially amenable to solution, as opposed to something that's "just the way things are". Intelligent people look at everything and ask, "Does it have to be that way?"
8. Heresy. Intelligent people are willing to question everything. They won't accept something just because that's the way you say it is; they reserve the right to rederive the result for themselves, and to reject it if they can't.
9. Open-mindedness. Intelligent people are willing to think about anything and everything. They don't say "That's not my problem" or "Oh, I'm not interested in that."

Now, the nice thing is that some if not all of the things on that list can be learned, or at least practiced and improved. All you have to do is want to, and be willing to work at it. —Steve Summit (talk) 15:37, 8 September 2007 (UTC)

P.S. A great way to practice some of these skills -- and that doesn't even have to feel like work -- is by playing good games. (Where by "good games" I mean "those that aren't primarily or wholly games of chance".) For example, it seems to me that bridge would be an excellent mind-stimulation game. (I confess, though, that I've rarely actually played it myself, and that many people might find it uncomfortably like work. :-) ) —scs

If your diet is detrimental to your physical development, then that may affect your intelligence, so in that case improving it would likely increase your intelligence. Omega 3 (such as in fish oil) is a good example. Nowadays many people don't eat a lot of fish, including me, so I take fish oil pills. There is some evidence that people who had brain injury benefit from large doses of fish oil. But for a healthy person, something like one herring per week would be sufficient. Whether large amounts of fish oil would benefit a healthy person is being researched, but still highly debatable. It most certainly makes them stink, though. :) DirkvdM 17:58, 8 September 2007 (UTC)

In response to Steve's list, I'd say there are just two basic aspects of intelligence: memory and creativity (for lack of a better word). Logical thinking, making connections, seeing patterns, heresy and open mindedness are just different ways to express the latter (though it doesn't hurt to list them all to get the point through, because, like I said, I can't think of a good single word for it). Thirst for knowledge is just a result of having intelligence, not an aspect of it. And I don't see discipline as an aspect of intelligence, unless it is meant as a result of the thirst for knowledge. Recognition of problems, however, is a good one. I'm not sure about that. It's certainly a trait of intelligent people, but if it's an aspect of intelligence or a result of it I'm not sure. DirkvdM 18:05, 8 September 2007 (UTC)

What, you're seeing patterns in the list? A good sign! :-) —scs

Blush. DirkvdM 07:43, 9 September 2007 (UTC)

• If you fill your brain with as many facts as you can, your creativity will have much smaller leaps to make between foot holds. Also, knowing many facts is often seen as intelligence by others, which has value in itself. So read a book. --Sean 19:32, 8 September 2007 (UTC)

That's some really bad advice, in my opinion. It used to be useful to know facts when there weren't a lot of books available nor the Internet, but nowadays there's no need for it. Only stupid people will see fact knowing as intelligence. I think it's best to think about things in which you're interested, talk with other people, and only read something if you're really curious, to satisfy yourself, not to be seen as intelligent by people who don't know what intelligence is. A.Z. 21:15, 8 September 2007 (UTC)

I didn't suggest learning things in order to be seen as intelligent, only that knowing a lot of things is seen as intelligent by many people. I respectfully disagree with your idea that the Internet has made being widely knowledgeable less useful. It's no good being in a situation that demands some insight and saying, "I could go Google this topic and then have something useful to say". Anyone could do that! --Sean 00:04, 9 September 2007 (UTC)

Yes, anyone can do that nowadays. Some centuries ago, we couldn't, so people who knew stuff that today Google knows were considered "intelligent". A.Z. 00:10, 9 September 2007 (UTC)

Be that as it may, there's a huge difference between knowing something, and knowing where to look it up.

I'm not saying that in many cases knowing where to look something up isn't sufficient -- we can't remember everything, so the ability to do research is a must. But if you're an expert in a field, you're not going to be able to make advances and do good work if you have to look something up every five minutes.

Consider a foreign language that you're knowledgeable of but not fluent in. If you try to read a book in that language, you either have to stop to look up unknown words multiple times per page, or you have to skim along, getting only a partial impression of whatever wonderful web of words and meaning the author has spun. Either way is less than optimum, and often quite unsatisfactory.

Or consider programing languages. In languages in which I'm expert, the limitation on how fast I can program is literally how fast I can type. But in an unfamiliar language, I'm constantly having to stop and scratch my head, or look up the name of a library function I think I need. —Steve Summit (talk) 00:56, 9 September 2007 (UTC)

Sean, a book? You mean one of those paper thingies? We're sitting on top of the biggest structured collection of information the world has ever seen and you recommend reading a book?? AZ, Google doesn't know anything. It's an index to sites that might (!) have useful info. But even those sites aren't themselves intelligent. Written info isn't intelligence, nor is it a substitute for it, it's an aid. In order to unleash your intelligence on info you first have to get it in your head. And the more info there is in there, the more connections you can make between all those facts, and that aids intelligence (as Sean pointed out). There's the two basic ingredients of intelligence again: knowledge/facts/memory and creativity/logic/patterndetection. And I wonder if even that distinction is valid. The method by which we reason is also the way we remember things. I've done a lot of thinking about this over the last two decades and I'm pretty convinced that there are some very simple rules that are applied at different levels and even to themselves, so that a small simple nucleus (apriori knowledge) can grow out to something very big and complex, provided it gets sufficient input and hardware to deal with it. DirkvdM 07:43, 9 September 2007 (UTC)

Why not a book? Being able to name 50 Pikachus and their characteristics may be useful and a sign of intelligence in some circles but personally and perhaps this is elitist of me I would say it's more useful to have knowledge of other stuff including a lot of stuff that is very or at least somewhat poorly covered in wikipedia like developing countries, science etc. Of course wikipedia may still be a starting point but you'd likely find you need to actually read some of the sources and recommended material eventually. I somehow don't think it's a good idea if your knowledge comes completely from wikipedia. But you know what they say, the best way to know your understand something is to try teaching/explaining it. We have the next best thing here. Once you've done your reading from the reliable source try writing/improving the article. Nil Einne 10:16, 9 September 2007 (UTC)

• Books are reliable sources; Misplaced Pages is not. There are other reasons, but that in itself is enough. --Sean 12:06, 9 September 2007 (UTC)

No source is ever fully reliable. Take the bible, for example. :) It's true that on average they will be more reliable than stuff on the Internet, but you always have to take that into account, whatever you read. Only scientific publications can be taken to be largely reliable, but the problem with those is that they are unintelligible to most people. Misplaced Pages is usually more legible than them but more reliable than most other 'popular' sources on paper, because it is cross-checked by others. Anyway, I was half jesting. :) DirkvdM 18:17, 10 September 2007 (UTC)

IQ is (as I said before) poorly defined - but IQ testers work hard to eliminate memory as an aspect of what they are testing. So I don't believe that the ability to remember all the characteristics of all of the Pokemon is a measure of IQ - nor do I believe that remembering all of the characteristics of all of the elements in the periodic table is a measure of IQ - nor any other large body of raw data. However, memory aids IQ in getting use through life and if you are a chemist, you'll be able to apply your IQ more efficiently if you memorise the periodic table than if you have to continually look things up. Memorising all of the Pokemon is an interesting curiosity and makes a great party trick - but beyond that, it's fairly pointless. The reason I recommend reading widely is because the act of being presented with a wide variety of ideas improves the way you connect up and understand knowledge. Cross-connections between disciplines is essential here. Becoming an expert in one very narrow field is not reflective of general IQ. There are plenty of examples of savants who have memorised things like the results of every baseball game in history - yet who have no interest in or understanding of the sport itself. Memory and IQ are both necessary - but they are unrelated skills. I have made a habit of reading three random Misplaced Pages articles every night before going to bed. I don't remember much of any of them - but the cross-connections of ideas are important. SteveBaker 16:24, 9 September 2007 (UTC)

Pokemon? I thought that was a Disney character (an Indian girl, I believe). The things I learn here. Now what might I cross-connect that with? :) DirkvdM 18:25, 10 September 2007 (UTC)

I mostly cross-connect it with a major argument with my kid about the merits of spending $125 on a 2"x3" piece of cardboard with some kind of a dragon printed on it. SteveBaker 19:22, 10 September 2007 (UTC)

Heaty food?

Hi everyone, I was just wondering what people mean when they say "don't eat too much heaty food"? —Preceding unsigned comment added by 116.14.180.26 (talk) 15:16, 8 September 2007 (UTC)

Heaty foods? Are you Cantonese by any chance. Or at least Chinese? Personally I've never really understood the concept much. Durian is supposedly a heaty fruit and you're not supposed to eat too much and counteract this by eating cooling fruit like Mangosteen. But other then that I don't really know the details much. But I can say from a scientific standpoint point it's mostly bull Nil Einne 15:27, 8 September 2007 (UTC)

It's probably rooted in pseudoscientific belief such as the theory of four humors. We also have a separate article called Humorism which discusses the "hot" and "cold" and "humid" principles. Of course, this has been wildly discredited as our knowledge of true anatomy increased. Nimur 16:39, 8 September 2007 (UTC)

I've never heard the word "heaty". —Tamfang 16:55, 8 September 2007 (UTC)

I hadn't either and at first I thought Nil Einne was joking or maybe teasing the OP about a misspelling, but a quick google search suggests that this is, in fact, the right concept. —Steve Summit (talk) 18:14, 8 September 2007 (UTC)

Basically all fried, oily stuff (chips, even instant noodles), lychee, durian, etc. are considered "heaty", which you will get sore throat, mouth ulcers and worsens acne. Whether you believe it or not it's still good to not be eating too much fatty fried stuff. --antilived 00:11, 9 September 2007 (UTC)

While it may have some basis in fact (as do many cultural norms), it's way too simplistic to be of any use IMHO. For example putting durian and lychee in the same category as chips is frankly a little dumb. For that matter according to this (not a reliable source I admit) butter is a cooling food... Indeed according to durian it's fat content is about 5.3%. High for a fruit I guess but I you'd have to eat a lot for it to be a big concern IMHO. The potassium content is likely to be a far greater concern from what I can tell yet foods with a high potassium content are supposed cooling! Also in terms of the ill effects of eating too much fatty food I've never even heard of it causing Oral ulcer & sore throats and the acne link remains unproven. Obviously poor nutrition in general is a bad thing for your health but I would have to say I don't find the list of ill effects of heaty foods particularl convincing either. Also I don't see any reason why you would have to eat mangonsteen (cooling food) to counteract the ill effects of heaty durian. Sure a balanced diet is good and it may be better to eat mangosteen then durian so if it reduces the amount of durian you eat I guess that's good but it's not counteracting the ill effects. So thats why all in all, I feel the concept is meaningless from a scientific standpoint. Nil Einne 08:44, 9 September 2007 (UTC)

I don't get much of an effect from durian but I dare you to eat a kg of FRESH lychee and see what happens... --antilived 08:23, 10 September 2007 (UTC)

I probably should have explained better for the benefit of those who never heard of the concept before. Basically I believe it's heaty because it's supposed to make your body (or spirit?) 'heat' up. The opposite is 'cooling' food. I've mostly heard of it in relation to fruit but as Antilived mentioned it's applied to all food I believe. Simplisticly that's why your supposed to eat cooling foods to counteract the ill effects of heat food I believe although too much heaty food in general is also considered bad. Also I may have been wrong about the Cantonese bit. I'd thought the concept was primarily a Cantonese one but it appears it may not be restricted to them. I forgot to mention from my searches e.g. , http://www.benefits-of-honey.com/heaty.html (link is on the spam blacklist) and other sources, it may have something to do with the Yin and Yang concept Nil Einne 09:06, 9 September 2007 (UTC)

Sunrise vs. Sunset

I always wondered why sunrise and sunset don't look the same. During sunrise, the sun is significantly brighter - I can't look at the sun during sunrise, but during sunset, it's a much deeper and less blinding red.

Not a single person I asked could give me a convincing answer on the subject. Maybe you can avail me? 82.166.190.58 15:55, 8 September 2007 (UTC)

I don't think I've ever noticed the phenomenon, but maybe what you're experiencing has to do with what your eyes have adjusted to. At dawn your eyes have adjusted to the darkness, so bright things seem that much brighter. At dusk, your eyes have gotten used to the bright blue sky and so aren't bothered at all by the dim red sun. Matt Deres 16:11, 8 September 2007 (UTC)

You could try to get photometric data to check whether there is any absolute difference in brightness for a given sun position. Nimur 16:36, 8 September 2007 (UTC)

There's more dust in the air in daytime. —Tamfang 16:54, 8 September 2007 (UTC)

Edit conflict. Especially if you live in an urban area pollution levels will typically be far higher at the end of the day after a day's traffic and other pollution, compared to the relatively clear air at dawn after a night's inactivity. That you in fact identify the sun as being a 'deeper and less blinding red' at sunset suggests there may be a greater effect from the particulate matter in the air scattering the sunlight more. See sunset which discusses this, also scattering and Mie theory. --jjron 17:08, 8 September 2007 (UTC)

Is it useful to have separate articles for sunset and sunrise? A.Z. 17:58, 8 September 2007 (UTC)

You mean sunrise and sunset? Or are you suggesting they should be merged? DirkvdM 18:09, 8 September 2007 (UTC)

Culturally and philosophically they are very different. I don’t see why they should be merged. --S.dedalus 05:42, 11 September 2007 (UTC)

In many places the sky tends to be clear in the morning and cloudier later in the say, presumably because the sunlight promotes evaporation of water which rises as vapor to an altitude where it re-condenses. A sunrise in a clear sky will be brighter than a sunset with clouds. --Anonymous, 21:47 UTC, September 8, 2007.

Say, but I was just about to say the opposite: in many places, there are regularly early morning fogs, which always burn off by the end of the day... —Steve Summit (talk) 21:56, 8 September 2007 (UTC)

I suppose that morning fog is close to the ground and will therefore have less effect on the incoming sunlight than clouds up in the sky. Except maybe when the sun is only just over the horizon and visible (ie no buildings or hills), which is often not the case. DirkvdM 08:00, 9 September 2007 (UTC)

There would also be less light pollution at dawn I guess Nil Einne 09:42, 9 September 2007 (UTC)

General Relativity

Hi, I'm german, so please excuse my poor english. I have a question concerning covariant derivatives: Consider a real-valued function f(x,x') in two arguments which are both from some manifold M. I want to take first covariant derivatives with respect to both arguments and I wonder if they reduce to partial derivatives like

${\displaystyle g^{\mu \nu }D_{\mu }D'_{\nu }f(x,x')=g^{\mu \nu }\partial _{\mu }\partial '_{\nu }f(x,x')}$.

The primed derivatives mark derivatives w.r.t. x'. I know that this formula would be wrong if I took both derivatives w.r.t. the same argument, because the first derivative would lead to a (co)vector quantity, which would demand the use of christoffel symbols for the second derivative. But I think in my case the quantity should stay scalar in x even after derivative w.r.t. x', because this would certainly be the case, if I considered x and x' being from different manifolds. Am I right? -- 88.76.244.169 19:07, 8 September 2007 (UTC)

Poor English? Wow, if I could handle covariant derivatives as well as you handle English I would be able to help you.Richard Avery 07:51, 9 September 2007 (UTC)

I believe you're correct. --Reuben 08:10, 9 September 2007 (UTC)

Light as a wave

Is there a known reason that, in one way of looking at light, it travels as a wave, or is that just one of the properties of the universe that is just because it is? 72.128.74.159 21:42, 8 September 2007 (UTC)

Whoops! Forgot to sign in. Imaninjapirate 21:43, 8 September 2007 (UTC)

You'll need someone a bit better versed in quantum mechanics to say whether there is a reason (though the question might actually be more metaphysics than physics), but light always travels as a wave. The photon only acts as a "particle" when it actually interacts with another particle (such as hitting something or being absorbed by something as a quanta of energy). --SB_Johnny | 23:33, 8 September 2007 (UTC)

Well, the good old classical explanation is that it is entirely the result of charge interacting through the coulomb force. Adding relativity to the equation, along with some other assumptions, yields Maxwell's laws (not that that's how they were originally derived). Maxwell's laws predict the existence of electromagnetic waves essentially as a mere consequence the laws themselves. But note that electromagnetic waves are force fields that possess wavelike characteristics, and are not the same as quantum mechanical wave-particles. Someguy1221 00:30, 9 September 2007 (UTC)

Alternatively, we might say that light is neither particle nor wave; light is just light. When we try to describe what it is doing, we find that it often behaves like a wave (which is a mathematical and conceptual construction defined by certain characteristics - see wave). Other times, it behaves like a particle - that is, a distinct entity with a specific quantity of momentum and energy and a definite location and a "trajectory" of motion. Whatever the actual property of the universe, we find that the wave model is a suitable description while light is propagating (traveling); and the particle description is a good approximation to what happens when the light interacts (hits something). Maybe both are right! Maybe both are wrong! It doesn't matter - we can make correct quantitative predictions about the behavior of light by using these descriptions in appropriate ways. Nimur 05:02, 9 September 2007 (UTC)

Bicuspid valve

Our article on Edith Bowman claims "Bowman was diagnosed with a bicuspid heart valve". Presumably this is a mistake (surely everyone has bicuspid valves), but every source I can find also simply says "bicuspid valve" (all use the same quote, apparently from ). What does bicuspid mean when used to mean some sort of defect - is it a defect with the bicuspid, or a bicuspid valve where she should have some other sort of valve? Laïka 22:11, 8 September 2007 (UTC)

It sounds like she misspoke, and meant to say "bicuspid valve problem", or some such. Another source says she has a heart murmur, so perhaps it's a mitral valve prolapse. But Ms. Bowman, if you're reading this, please don't take it as medical advice! --Sean 00:13, 9 September 2007 (UTC)

There's no reason to assume that a heart murmur indicates a mitral valve problem. In fact, the most common valve problems are mitral and aortic stenosis, not mitral insufficiency (as suggested by MVP). A bicuspid valve could refer to a bicuspid aortic valve, whose prevalence is approximately 1.4% wordlwide. --David Iberri (talk) 05:08, 9 September 2007 (UTC)

hydrocodone vs.oxycodone

what is the diference between hydrocodone and oxycodone? —Preceding unsigned comment added by Twdyer (talk • contribs) 22:14, 8 September 2007 (UTC)

Have you looked at our articles on hydrocodone and oxycodone? Splintercellguy 22:48, 8 September 2007 (UTC)

Looks to be an OH group Algebraist 23:26, 8 September 2007 (UTC)

Just browsing the hydrocodone article, there is a completely unnecessary bit of information detailing how one might extract hydrocodone from the Tylenol it is commonly paired with. It suggests that some patients with liver problems extract the hydrocodone in pure form since acetaminophen is metabolized by the liver. This would never be requested of a patient. A quick glance at my Pocket Pharmacopoeia shows me that there would a)be several alternatives were this really a problem and b)hydrocodone is also metabolized by the liver... So, the information on how to separate the two drugs seems to be of use only to someone who wants to separate the two for another reason. I don't think it should be available in such an obvious place.
Mrdeath5493 05:56, 10 September 2007 (UTC)

Makes it sound like article has undue weight on such a rare legit action or else is missing some cites for what sounds like WP:OR. Along with UNDUE, it's got way too much detail in light of Misplaced Pages is not a how-to manual, especially for something that could be taken as health advice. Let's take this to the Talk:Hydrocodone page, which has previously discussed this section of the article. DMacks 06:03, 10 September 2007 (UTC)

It's a drug abusers "how to". Hydrocodone paired with acetominophen is not as regulated (class III vs. class II in the U.S.) and is therefore easier to obtain. Too much aceptominpohen will cause vomiting and other unpleasantness and therefore reduce it's effectiveness to get high. This is why it has a different classification for the DEA. it's illegal and dangerous to do this so it should be removed. --DHeyward 06:10, 10 September 2007 (UTC)

I'm not sure how these things usually go on Misplaced Pages, but that particular snippet of information should be excised. Should I just do it?
Mrdeath5493 03:07, 11 September 2007 (UTC)

I did but it was reverted. I removed it again as it isn't reliably sourced. --DHeyward 04:03, 11 September 2007 (UTC)

September 9

Angioplasty vs. Thrombolytics

Which is the more effective treatment for an acute myocardial infarction - percutaneous coronary intervention or thrombolysis? Does a physician ever have to choose between the two? —Preceding unsigned comment added by John1234567890 (talk • contribs) 01:02, 9 September 2007 (UTC)

For acute MI, the most effective approach is cardiac catheterization lab assessment (which often involves recanalization of an occluded vessel). For institutions that don't have a cath lab, thrombolytics are the most appropriate secondary approach, while they send patients to a hospital with a cath lab. --David Iberri (talk) 05:05, 9 September 2007 (UTC)

Ozone cleaner

I'm having difficulty finding a device that will clean ozone out of a room. If you type "ozone" and anything remotely close to "cleaner" or "filter" into a search engine, you come up with hundreds of ozone generators. I want the exact opposite - a device that will convert the ozone in an ozone-rich room to something less hazardous, such as O₂. Is there anything like that available on the open market? -- kainaw™ 01:15, 9 September 2007 (UTC)

Had a bit of an electrical problem? Hopefully you weren't tossing food in front of a microwave RADAR to warm it up! (Sorry, I have no idea how to absorb ozone; maybe you could spray some CFCs around?) Nimur 05:05, 9 September 2007 (UTC)

Incidentally, ozone specifies that the decay time of O3 to O2 in atmospheric conditions is less than a half hour. If you are still having problems with ozone / ozone smell, maybe you have a more serious problem - some other chemical hazard? Insert standard "seek professional advice" comment... Nimur 05:11, 9 September 2007 (UTC)

Potentially whatever is generating the ozone is still operating. Have you isolated the source yet? I remember I once had a defective light producing ozone but it could be anything electrical potentially. If you're unable to operate in the room because of the ozone, I would suggest you do what you would do if you have a shortcircuit. Turn off the room or house's power at the fuse box, ventilate the room and then turn off everything in the room. Turn the fuse back on and turn each device on one by one. Make sure you keep the room ventilated of course Nil Einne 09:31, 9 September 2007 (UTC)

Google remove ozone. 152.16.59.190 07:11, 9 September 2007 (UTC)

Ventilation? DirkvdM 08:01, 9 September 2007 (UTC)

Thanks. Ventilation is not an option and the source of the ozone is well known (liquid oxygen storage and a small room with over 300 power supplies sharing a closed-loop air conditioning unit). The ozone remover from the anonymous user's Google search should work well - if I can get administration to order one. Maybe I can find some OSHA regulation to force the issue. -- kainaw™ 15:28, 9 September 2007 (UTC)

As Nimur says - the stuff decays naturally in 30 minutes or so. So it won't build up indefinitely unless there is really inadequate ventilation. If the amounts you are producing is so high as to represent a health risk even with that decay rate, then I think you have something causing arcing in those power supplies and the ozone is the least of your problems. Personally, I think I'd just install some big fans and blow it out to atmosphere. It seems like it should dilute rapidly and decay before it can do any great harm. However, this is definitely one of those "Seek professional advice" things. SteveBaker 16:07, 9 September 2007 (UTC)

Some copy machine and laser printers have an ozone filter. I can't imagine how it works, though. My understanding is that you have to dilute it, or let it oxidize something. --Mdwyer 03:49, 10 September 2007 (UTC)

A catalyst to accelerate the decomposition of ozone back to molecular oxygen seems reasonable. Google for ozone decompose catalyst to see los of examples, including many that don't look like Infomercial crap. DMacks 07:07, 10 September 2007 (UTC)

Tin Oxide is used I believe. Polypipe Wrangler 11:01, 12 September 2007 (UTC)

Detection of Maltose

I need to find a way to detect the appearance of maltose, or measure the rate of hydrolysis in starch? My project includes taking corn starch with different pH values, and testing the effect of amylase at different pHes on hydrolysis. Any help appreciated. —Preceding unsigned comment added by Blooooo (talk • contribs) 02:40, 9 September 2007 (UTC)

This might be expensive, but you can use maltase and then look for glucose. ←Ben 03:11, 9 September 2007 (UTC)

The old iodine trick should work. Iodine will turn starch blue. But I don't think it will discolour maltose. I don't quite know what the effect of pH is on the colour of Iodine though, so this might make things a bit more difficult.PvT 13:07, 9 September 2007 (UTC)

Even if there is a pH effect, you could do the test on a sample at the instant it's exposed to the conditions and compare it to one on a sample after some time. That way you're comparing two results that were under the same pH conditions (and then examine this change with respect to pH or amylase). Any time you have a variable, you need some sort of control group to see what its effect is, both on "what you're testing" as well as on the mechanism of the testing itself. DMacks 15:11, 9 September 2007 (UTC)

Thanks for the help everyone. I plan on using amylase (can't get maltase apparently) and checking the pH at every point of the expirement, before amylase, after amylase, before iodine, and after iodine and then repeating the experiment for discrepancies. Blooooo 19:57, 9 September 2007 (UTC)

You could detect the hydrolysis of starch by other means. For example, you could make some starch gels ready for electrophoresis. Do the various treatments, and then electrophorese some standard things. Check with someone who does this sort of thing. Polypipe Wrangler 11:12, 12 September 2007 (UTC)

Seeing the future

What is the chance that someone born in 1992 will live to see the year 2100? --124.254.77.148 08:48, 9 September 2007 (UTC)

• This question obviously calls for speculation, so I'll speculate: I consider the chances to be rather low that anyone will be alive in 2100. In 1892, there was no foreseeable technology that could wipe out all of humanity. Just a half century later that was no longer the case. The democratizing nature of technology means that smaller and smaller entities become more and more powerful over time. In the beginning only the most powerful nations could build nuclear weapons; now some of the poorest in the world have them. It's easy to imagine that in the next 100 years individuals will have access to that level of destructive technology, in the form of genetic engineering, nano-technology, nuclear refinement, or -- more likely -- some unforeseen technology. At that point, all humanity will be subject to the Columbine/Virginia-Tech/September-11 crazies of the world. In short: don't buy any green bananas. --Sean 13:46, 9 September 2007 (UTC)

You sound like Debbie Downer. —Keenan Pepper 17:30, 9 September 2007 (UTC)

• It may call for speculation regarding causes and specific cases, but it can likely be answered in a statistical sense by reading Life expectancy#Calculating life expectancies. DMacks 15:05, 9 September 2007 (UTC)

Based on recent mortality data from Canada shown here, out of every 100,000 babies born 99,268 survive to age 15 and 31 survive to age 108. So the probability that someone born in 1992 who has survived to age 15 in 2007 will survive a further 83 years to 2100 is 31/99,268, or about 0.03%. This assumes mortality rates remain unchanged for the next 80 years - in practice, they may well improve (leaving aside Sean's pessimistic scenario) so the probability may be higher (50 years ago the probability of a new born baby surviving to age 108 was only 0.003%). The actual probability for a specifc individual will be affected significantly by factors such a gender, life style, access to health care etc. Gandalf61 15:15, 9 September 2007 (UTC)

Thank you, that's the kind of answer I wanted. :) --124.254.77.148 07:46, 10 September 2007 (UTC)

The maximum age humans could possibly reach is sometimes said to be somewhere around 130 years. For the largest part, this has to do with dna strands getting shorter every time they are copied or something (don't know the details). At the moment, in western Europe, people grow to be around 80 on average. Over the next hundred years we're bound to get a fair bit closer to those 130 years. So if the average age has risen from 80 to 108 then that number would be 50%. Mind you, that is in the West, and assuming no catastrophies like war or drastic climate change. See also maximum life span. For a completely different option see the first item in this section on my user page. DirkvdM 18:44, 10 September 2007 (UTC)

You might also want to check back through our archives to several long and interesting threads about the highly controversial (but very entertaining) theory of quantum immortality which would suggest that everyone lives forever as far as they themselves are concerned. SteveBaker 19:18, 10 September 2007 (UTC)

wave ball

i was watching a re-run of nickelodeon's global guts and they had a wave ball in a pool that creates waves. could you please tell me how that ctually works? —Preceding unsigned comment added by 71.165.201.93 (talk) 08:48, 9 September 2007 (UTC)

Wave pool and . They don't mention a wave 'balls' specifically but the basic concept is going to be the same. It might also help if you think of dropping a pebble in a body of water. You generate (small) waves. Basically the wave ball is doing the same thing but biger waves (think of dropping a rock) and at continually intervals. Nil Einne 09:30, 9 September 2007 (UTC)

Here are some specifications of "wave balls". As one might expect, the basic principle is a ball with a large amount of mass in it that is moved up and down to create waves. This particular company's product that I linked to seems to do some calculations as well to decide when the optimal time to move the weight up and down is, allowing it to multiply existing waves (and thus generating larger waves with less energy). --24.147.86.187 21:32, 9 September 2007 (UTC)

Yes using constructive interference makes a lot of sense. Somehow I never thought of that Nil Einne 20:39, 12 September 2007 (UTC)

see www.wowcompany.com for the Wave Ball

Sensation of Vertigo

I used to think that the sensation one gets when looking over a cliff is that of "vertigo" but after reading the word's definition it doesn't seem to be the case. Is there a word for the sensation you get when looking over a precipous? Not a dizzying or moving sensation but rather, I am embarassed to say, something felt in the genitals. Again is there a name for this? 207.69.139.135 09:36, 9 September 2007 (UTC)

According to Acrophobia the sensation is best described as a spinning sensation. It doesn't mention any feeling in the genital region however Nil Einne 09:51, 9 September 2007 (UTC)

When faced with even the thought of a remarkably steep cliff or something involving heights and a falling hazard, I get a very tingly sensation under my feet. 81.93.102.185 10:53, 9 September 2007 (UTC)

When looking off a tall structure at a dizzying height, I usually have to fight the urge to jump. I'm not a suicidal person, but I've always had this compulsion. I think it has something to do with my mind trying to break the suspense. --Sean 13:28, 9 September 2007 (UTC)

Better read The Imp of the Perverse. —Steve Summit (talk) 14:35, 9 September 2007 (UTC)

Read it? I wrote it! --Sean 21:54, 9 September 2007 (UTC)

Did you! Well, then, my hat is off to you! —Steve Summit (talk) 22:51, 9 September 2007 (UTC)

There was a question about this jumping sensation on the desks a few months back, but i'm awful with searching archives. It was created by myself but I was probably acting under an IP at the time. Can any ultra-searchers find it? Capuchin 09:54, 10 September 2007 (UTC)

Misplaced Pages:Reference_desk/Archives/Language/2007_April_12#Desire_to_jump_from_a_height --Sean 13:24, 10 September 2007 (UTC)

Better not read just do it. I must admit I thought this feeling was vertigo. You don't say exactly what happens in the genital region, but could that just be scrotal piloerection?--Shantavira| 17:55, 9 September 2007 (UTC)

I can concur with the unpleasant sensation when looking down from a great height, but never from an aircraft. I had always assumed this was vertigo. There is an unpleasant sort of "butterflies in the stomach" feeling but also a similar sort of sensation in the genitals, not piloeraction but a deeper uncomfortable sensation perhaps like the testicles being drawn up. I have never experienced giddiness - just the sure and certain feeling that this high vantage point is going to collapse. However the good news is that if you force your self to stay there the feeling will pass, maybe 5 minutes maybe 15 but it will go. It took at least 15 minutes at the top of the Space Needle! Richard Avery 07:47, 10 September 2007 (UTC)

"Natural genetic engineering"

Hello. I'm just a high school student. In searching around the internet I've run across a concept, "natural genetic engineering," which I can't quite grasp due to the high level it's discussed at. It's all related to a certain biologist named James A. Shapiro. Can someone explain to me, in layman's terms, what this is? In particular I'm interested to know if it means that the life forms undergoing "natural genetic engineering" somehow "know" how to adapt to a new environment. Here are some links:

http://shapiro.bsd.uchicago.edu/index3.html?content=genome.html shapiro.bsd.uchicago.edu/2007.Colchester.pdf http://members.aol.com/jorolat/nge.html http://www.springerlink.com/content/v655m288l6457115/

Any help appreciated. Thanks. 76.247.78.219 19:05, 9 September 2007 (UTC)

I might be too much of a fool to understand it, but it sounds like what he is calling "natural genetic engineering" is what the rest of the world calls "genetics." "Natural genetic engineering" is something of an oxymoronic term, if you ask me — genetic engineering implies human manipulation of what would otherwise be solely in the realm of nature; making it "natural" means removing the human component, yes? The work, from a brief skim, seems to be about the complicated ways in which genetic code can self-regulate and self-correct and that there is code which controls code and the like. All of which is true, but last I checked was subsumed by the definition "genetics" and, without human intervention, is not "genetic engineering" of any sort. The genetic code is quite complicated, and if he is just using the term to get outside of the simple "standard dogma" approach to genetics (which has been known to be misleadingly simple for a long time), I guess that is fine, but if you ask me the right way to do it—and the way most scientists seem to consider it—is to think of that complexity as being part of the definition of "genetics". Genetics has all sorts of regulatory functions built into the code itself—it is like a program that can reprogram itself, aside from doing all sorts of other things—and unless I've missed the mark, that's what he's chosen to label "natural genetic engineering." --24.147.86.187 21:27, 9 September 2007 (UTC)

I'm not an expert either, but it sounds like you got the basic idea right--the organism rearranges its genome in response to environmental changes. I've taken basic genetic sources but have not learned anything about that. What I've read about genetic adaptation are things concerning post transcriptional changes and feedback systems. An example of post transcriptional changes is when the transcribed DNA is spliced and rearranged. Feedback systems concern the regulation of protein production, where depending on the condition in the cell, the rate of a protein's synthesis is adjusted accordingly. The adaptation the guy talks about seems to infer changes in the genome itself. That is, sequences of DNA are rearranged to produce new programs (correct me if I'm wrong, anyone). The post transcriptional changes and feedback systems don't have anything to do with changing the genome. 128.163.224.222 21:44, 9 September 2007 (UTC)

For an opposing viewpoint: I was talking some time ago to a biologist I knew, and expressing dismay over some dangerous-sounding bit of "genetic engineering" that was then in the news, and he made the point that, in his view, he couldn't see any difference between that and regular old natural selection.

• Natural selection: organisms are selected based on their "fitness for the environment", where this fitness is actually determined by how successfully they reach maturity and reproduce. Random mutations (induced by e.g. cosmic radiation) introduce variability which may produce superior environmental adaptations which will then be selected for. Also, viruses and other pathogens occasionally swap bits of genetic material between unrelated species; this can produce spectacular mutations (which, again, if beneficial will then be selected for).
• Generic engineering: organisms are selected based on how successfully they reach maturity and reproduce, which is determined by whether some humans like the way they've come out, and let them reproduce. Random mutations (induced perhaps by deliberately-applied radiation) introduce variability which may produce desired adaptations which will then be selected for. Also, those humans may contrive to swap bits of genetic material between unrelated species; this can produce spectacular mutations (which, again, if beneficial will then be selected for).

The point is that, other than that there's an external agent attempting to direct the process towards a predetermined goal (which is, of course, most unlike natural evolution), there's really no difference in the underlying mechanisms or the potential outcomes of the "natural" versus "artificial" selection processes. —Steve Summit (talk) 01:59, 10 September 2007 (UTC)

Softwood shipping Grade Markings

Sorry to ask this question again, but I can't get the answer, please does anyone know where i can get the softwood shipping markings? I have them from 1976 but most have chaged as lots of new ones out now, The main places the wood markings are needed from is Sweden, Finland and Russia I hope someone can help this time, I have been searching for then for weeks thank you Jasimps —Preceding unsigned comment added by 86.130.174.194 (talk) 19:27, 9 September 2007 (UTC)

Can you ask a timberyard? I don't think there are many timberworkers online editing the science reference desk. Graeme Bartlett —Preceding unsigned comment added by Graeme Bartlett (talk • contribs) 06:52, 10 September 2007 (UTC)

Generally, if you get no responses after a couple of days it's because none of us know the answer. Continually re-asking the same question isn't going to get you anywhere. All reasonable questions are typically researched by at least a couple of people. For the record, I searched all over the place on the web and in paper encyclopedias in an attempt to answer your question the first time you asked it. I was able to find odd reports from conferences where shippers discussed timber markings - but I couldn't find any resource describing what they actually were. So sadly, I doubt anyone here will be able to help you. I like Graeme Bartlett's suggestion of asking someone who deals with timber shipments. But this service isn't magical - whilst we can usually come up with something, if the information just isn't out there, we can't find an answer for you no matter how many times you ask. Sorry. SteveBaker 12:40, 10 September 2007 (UTC)

True. But there's no need to scold the OP -- somewhere, in one of our RD instructions or guidelines, is or was the statement suggesting it's fine to re-ask a question after a week or so. —Steve Summit (talk) 12:53, 10 September 2007 (UTC)

Thank you all for trying anyway, I have been scolded and wont ask again! —Preceding unsigned comment added by 86.130.174.194 (talk) 13:21, 10 September 2007 (UTC)

Per the Ref Desk guidelines, it's perfectly OK to re-ask a question - and I'm certainly not scolding anyone for doing it. What the RD guidelines don't say (and they probably should) is that your odds of getting a decent answer fall to approximately zero if you didn't get anything useful the first time you asked the question. It's a sad fact of life that we can't answer everything - and if we can, we generally do so the first time around. SteveBaker 19:11, 10 September 2007 (UTC)

Creatine and Body Fat Percentage

I had my body fat percentage measured two weeks ago and it was 11.2%, but this week it was 13.5% using the same machine (its this thing that you put on your arm and I guess it sends a signal through you). I havnt gained any weight and my measurements havnt changed either. Is it because I started taking creatine? —Preceding unsigned comment added by 76.167.139.80 (talk) 20:34, 9 September 2007 (UTC)

It's probably just a reflection of statistical error in the technique used to measure body fat. Also, from your description, I'm guessing the apparatus you're using uses bioelectrical impedance analysis (BIA) for its measurement. I don't have any personal experience with the technique, but according to our article on BIA, it's apparently an inferior technique for measuring percent body fat. That in itself may account for the error.

Creatine by itself doesn't have an effect on muscle mass (and there aren't enough convincing data out there to reliably say creatine supplementation is at all worthwhile), but chances are that if you're taking creatine you're also weight training. In the long-term, weight training increases muscle mass and decreases body fat, although two weeks of it is unlikely to cause a dramatic change. --David Iberri (talk) 00:51, 10 September 2007 (UTC)

dietary supplement

what is and what is it used for .....Omega 3 Fish Oil?

angieb4756 —Preceding unsigned comment added by 12.207.120.234 (talk) 20:50, 9 September 2007 (UTC)

See Omega 3 fatty acid. Someguy1221 20:58, 9 September 2007 (UTC)

September 10

Problem with Video Divs on the Reference Desk

Hello fellow reference deskers. There seems to be a glitch in syntax which is botching up the formatting for the video files posted above. (My guess it is in Template:Video, but I'm not sure). Can anyone figure this out? Surely it's wreaking havoc on other pages which use the video template, and it's doing terrible things to the Reference Desk. Nimur 01:26, 10 September 2007 (UTC)

Glitch is right! For some reason the two videos are sitting at the bottom of the page now (at least under my version of Firefox). I tried removing the <div>'s and <br> that Nimur had inserted, thinking that would help, but that led to a cascading-indent problem. Then I tried inserting a {{--}} template, which usually fixes those, but that rendered all the following sections bizarrely uneditable! WTF?! —Steve Summit (talk) 02:37, 10 September 2007 (UTC)

I've commented out the offending videos - we can't have one fscked up question screwing up the entire ref desk. SteveBaker 03:41, 10 September 2007 (UTC)

I just fixed what looked to me as two bugs in Template:Video, one of which was related to <div> usage. Now this historical form of the page appears to render correctly (or at least not crappily) for me (x11 build of Firefox1.5 on OS X). DMacks 04:23, 10 September 2007 (UTC)

Can you kill yourself with a knife

I was watching "Rome", the HBO show, and it shows a woman standing on her knees, bringing her knife to her breast quickly, thrusting, and immediately falling dead. How realistic is that? It seems quite hard to be able to a) thrust the knife in the point which contains the right spot on the chest (wherever that is), b) to thrust it with enough strength by yourself, without being weakened by the pain which occurs right after you break the skin and c) to die pretty immediately (as opposed to dying from somewhat slow-occurring blood loss).

What are the chances of successfully doing a? What are the chances of successfully doing a & b? What are the chances of doing a & b & c?

Assuming the person has lay understanding of anatomy and average strength, of course. —Preceding unsigned comment added by Knyazhna (talk • contribs) 01:38, 10 September 2007 (UTC)

See Hara-kiri.

The dagger to the breast is indeed a popular device in fiction, but I don't find it too far-fetched. A stab wound to the heart is, if not immediately fatal, nonetheless quite definitive and unrecoverable. You may not bleed out instantaneously, but it won't take long. (It most certainly will not be "somewhat slow-occurring".) And with a sharp knife, you can pretty easily slip between the ribs and puncture the heart. Yes, there'll be a moment of intense pain, but once your hands and arms are in motion I'd imagine you could follow through.

—Steve Summit (talk) 02:14, 10 September 2007 (UTC)

Thank you for your answer, but it's not quite "there". First of all, harakiri does not really apply, since you can see that by the ritual (first you cut your stomach, then your helper cuts off your head), one could be quite unsuccessful in actually killing oneself by one's own knife, and still complete harakiri (you just need good help). Also, Japanese swords are quite known for their sharpness. What is the likelihood that a woman's dagger is that sharp? Or at all sharp on any given day? Were there regular weekly sharpenings for lady's knives?

Secondly, I realize that it's possible for a&b&c to occur; I was wondering about the actual probabilities. Is it 80%? Is it 30%?

And, no, I'm not going to "try it at home" :) It really won't result in a scientific answer to my question, just anecdotal evidence. 02:57, 10 September 2007 (UTC)02:57, 10 September 2007 (UTC)~~

a: 89.1%. ("You can pretty easily slip between the ribs and puncture the heart.")

b: 76.4%. ("Once your hands and arms are in motion I'd imagine you could follow through.")

c: 93.7%. ("You may not bleed out instantaneously, but it won't take long.")

a & b: 89.1 × 76.4 = 68.07%

a & b & c: 89.1 × 76.4 × 93.7 = 63.7838%

Better than 50-50 odds. You're right: not something to try at home. —Steve Summit (talk) 03:36, 10 September 2007 (UTC)

In Seppuku, only the men disembowled themselves. Women put the knife through their throat. I suspect their is a way to rapidly reduce blood pressure in the brain which would cause near immediate unconsciousnes. --DHeyward 08:02, 10 September 2007 (UTC)

I think the original poster is referring to the suicides ordered by Nero after the discovery of the Pisonian conspiracy. Our article on Seneca the Younger says that he cut his wrists and took poison and his wife attempted suicide by cutting her wrists. Our article on Lucan says he "opened a vein". I suspect that the dagger to the heart scene is a piece of dramatic licence. Gandalf61 08:54, 10 September 2007 (UTC)

Cato pulled out his own intestines following the Caesar-Pompey Roman Civil War, there's a new method for you to consider! He supposedly ripped out his own stitches from a previous semi-first-stage-hari-kari attempt and just yanked them out.... SGGH 14:41, 10 September 2007 (UTC)

Cato really had guts, and no one could deny it. Edison 14:51, 10 September 2007 (UTC)

Under the subsection Seppuku in modern Japan it says that in “In 1999, Masaharu Nonaka . . . slashed his belly with a sashimi knife to protest his forced retirement. He died later in the hospital.” So I guess you can at least cut your belly. I have also heard however that there is a reflex that stops most people from stabbing themselves, which is why people must literally fall on their knives. Either way I’m pretty sure it would be a quite painful death. I think if you were hyped up enough on adrenalin it might be realistic though. One other thing, I saw a performance of Romeo and Juliet where Juliet stabs herself UNDER her right ribcage. Anybody know if this is realistic? --S.dedalus 22:57, 10 September 2007 (UTC)

Probably she was stabbing up under the ribcage towards the heart instead of trying to go between the ribs. I could not recommend the ease of this route in practice, but I believe that it is at least easier theatrically. Eldereft 20:25, 11 September 2007 (UTC)

aircraft weapons

i herd that during one of the world wars a fight aircraft was built and it had the machine gun placed behind the propeler.when the pilot was shooting the bullets would fly right between the propellers arms without ever touching them.please tell me if this is possible and explain if you can.thanx (please excuse the spelling not an english native) —Preceding unsigned comment added by 70.1.213.243 (talk) 02:43, 10 September 2007 (UTC)

See Synchronization gear. —Steve Summit (talk) 02:50, 10 September 2007 (UTC)

Yep. The earliest planes had a V-shaped metal plate bolted to each blade of the propellor that would deflect bullets from the machine gun so they wouldn't shoot off the propellor blades - but this was kinda dangerous because the deflected bullets would fly off in all sorts of dangerous directions! Other aircraft were built with 'pusher' propellors mounted on the back of the plane so that a machinegun could fire forwards - but those planes had unwieldy twin-boom tailplane setups. Yet others used machineguns mounted on the top wing so that they would clear the prop - but those were harder to aim. The later invention of the 'interrupter gear' had a cam mounted onto the engine shaft that would push a lever to turn off the machinegun for a fraction of a second to allow the propellor blade to go past unscathed. These things eventually became used on all aircraft on both sides of the war. By WWII, the wings of modern monoplanes were sufficiently strong that guns could be mounted out to the sides of the prop - some planes had hollow prop-shafts with a gun that fired right through the center of the hub of the prop. Between those things, the interrupter was pretty much obsolete.SteveBaker 03:50, 10 September 2007 (UTC)

But numerous WWII aircraft continued to use them, such as the Me-109, IIRC. Someguy1221 04:42, 10 September 2007 (UTC)

Shotgun speaker

Would the "shotgun speaker" design at http://forums.keenspot.com/viewtopic.php?p=3063548#3063548 actually work, and if so, how does it manage the directionality? --Carnildo 03:22, 10 September 2007 (UTC)

A parabolic dish with a small speaker at the focus of the parabola and aimed back at the dish should do the job. The larger the dish the better (because - relative to the size of the dish - the speaker will be more concentrated at the focus). SteveBaker 03:33, 10 September 2007 (UTC)

You can see (and hear) this latter design in many museums, where they are used so that only a listener located directly below the speaker hears the narration for the exhibit they're looking at/interacting with.

Atlant 17:09, 10 September 2007 (UTC)

I know a parabolic reflector works. What I want to know about is the "shotgun speaker" design at that link. --Carnildo 21:18, 10 September 2007 (UTC)

That was the answer. There is a parabolic reflector inside and that's how it manages directionality. If you need more information, tell us specifically what you need. Perhaps you don't understand why a parabolic reflector results in strong directionality? If so, reply here and I can explain it. SteveBaker 14:20, 11 September 2007 (UTC)

I don't see any parabolic reflector in that description. As far as I can tell, the post is describing a bundle of steel pipes of selected lengths encased in a PVC pipe. --Carnildo 20:46, 11 September 2007 (UTC)

I'm assuming that a "shotgun speaker" is the logical inverse of a shotgun microphone; I suppose there's no reason such a device shouldn't work.

Atlant 14:21, 12 September 2007 (UTC)

urgent biology question

Here is a situation " Some babies are allergic to milk. A similar fluid made from plants can be used as a milk substitute.These fluids must be well tested to ensure that they are as nutritious as milk. They are usually tested on rats.

what is a suitable method that could be used to carry out this experiment and what apparatus would be required?

Your assistance would be much appreciated. Thank you. —Preceding unsigned comment added by 208.131.186.18 (talk) 05:18, 10 September 2007 (UTC)

This looks like homework. Have you seen Laboratory rat? Graeme Bartlett 06:59, 10 September 2007 (UTC)

Would "a similar fluid made from plants" be soy milk?--Shantavira| 08:08, 10 September 2007 (UTC)

Just in case you have an "urgent biology question" because you want to test your milk substitute befoe you give it to your baby, I must remind you that wikipedia does not give out medical advice SGGH 14:42, 10 September 2007 (UTC)

Well, you'd take two bunches of rats - feed one lot milk and the other lot your plant-based concoction. Measure growth rates, disease rates, test IQ by running them through mazes, look for behavioral abnormalities, measure life span, fertility, etc. However, that wouldn't be enough. There could be chemicals in your plant-based pseudo-milk that would be carcinogenic over a period of time longer than the life-span of a lab rat. In practice, I suspect the process with Soy Milk was more like "We know there is nothing nasty in Soy beans because people have been eating the stuff for millenia - so if we liquidize them and feed it to babies, it shouldn't kill them." - you'd also have to look carefully for signs of deficiencies in the babies diets - probably adding a bunch of vitamins and minerals to make up for whatever is missing. SteveBaker 19:04, 10 September 2007 (UTC)

How many times has flight evolved?

Our article on flying and gliding animals says that flight has evolved at least four times in the animal kingdom: in insects, pterosaurs, birds, and bats. However, I seem to recall that the number should be five times, as insects have evolved two separate forms of flight; the mechanism works differently for a dragonfly than it does for a moth, for example. Is this correct? Has flight evolved four or five different times? — Brian (talk) 07:13, 10 September 2007 (UTC)

Would ya believe that we have a whole article on insect flight? It sounds like what you are talking about is the difference between direct and indirect flight, according to that article. Fascinating stuff, I had never given it a moment's thought before! --24.147.86.187 07:40, 10 September 2007 (UTC)

I think the key here is the "at least" part. In any case, I did a Google search for "the evolution of flight" and the first hit was a UC Berkeley site. It doesn't say much about insects, but has a good deal of vertebrate info. After the first search, I did a new search for the "evolution of flight in insects". And I got a bunch of cool stuff, but no dice on your question. So I plugged in "how many times did flight evolve", and I got this article, which says:

1. some investigators regard winged insects as polyphyletic (Matsuda, 1981)

2. majority favor monophyletic origin

3. Marden and Kramer (1995) defend idea flight could have evolved more than once

So I guess it is a bit, up in the air, so to speak. If you need me to find those specific refs for you, contact me on my talk page, I can email you pdfs (I gots lots of access to library sites :) ) --Cody Pope 09:08, 10 September 2007 (UTC)

The original quote said at least 4 times. The answer might well be more than 5 because we do not have the opportunity to study all of the billions of extinct species. It's perfectly possible that other animals evolved flight - but subsequently became extinct. Hence an at least statement is probably the best we can make. SteveBaker 12:29, 10 September 2007 (UTC)

Well, I suppose the subtext was "How many times has flight evolved individually in insects?" From Cody Pope's research, it seems that the majority opinion is once, although some folks think it's twice. — Brian (talk) 12:39, 10 September 2007 (UTC)

Flying fish, anybody? — PhilHibbs | talk 12:44, 10 September 2007 (UTC)

I'll see your fish, and raise you a flying squirrel. --LarryMac | Talk 14:49, 10 September 2007 (UTC)

Both flying fish and flying squirrels (+foxes, snakes, spiders, frogs, etc) are gliding - they can't sustain flight. After an initial jump, they can only lose altitude. Birds, some insects and bats can gain altitude by flapping. SteveBaker 18:51, 10 September 2007 (UTC)

Actually, The Flying Nun was only a glider, too. :) — Scientizzle 21:25, 10 September 2007 (UTC)

The Flying Nun? — Scientizzle 16:29, 10 September 2007 (UTC)

I know you're joking, but I think it's fair to count human flight. We can fly farther, faster, higher, and longer than any other species. And if we haven't "evolved" a way to fly, then neither have chimps "evolved" a way to get termites out of their nest with a blade of grass. --Sean 17:53, 10 September 2007 (UTC)

Are you sure about that? It's perfectly possible for a species to have a gene for making and using a specific tool. Human flight isn't "evolved" (in the genetic sense) - but (for example) Starlings can smash open a snail shell with a pebble even if they've never seen another starling do it - which suggests a genetic basis for their tool use. A single human would be unlikely to be able to build and fly an airplane if they'd never met another human before. I don't know whether tool use in Chimpanzees is genetic or learned. SteveBaker 18:57, 10 September 2007 (UTC)

Unfortunately I can't remember any specific examples just now, but there are definitely some animal behaviors that are passed on by observation and imitation, rather than being instinctive. --Steve Summit (talk) 20:00, 10 September 2007 (UTC)

My Flying Nun link was definitely a joke. :) I would understand the question "How many times has flight evolved?" to be strictly bounded by heritable genetic information resulting in body designs capable of true flight (not gliding). Human flight has no genetic root, so it's not an "evolved" behavior in the classic biological sense. The concept, however, might qualify as a meme; memetic theory incorporates many Darwinian elements. — Scientizzle 21:25, 10 September 2007 (UTC)

Here's an article that ties together two recent reference desk threads: R. Dudley, Atmospheric oxygen, giant Paleozoic insects and the evolution of aerial locomotor performance. Journal of Experimental Biology, Vol 201, Issue 8 1043-1050. --Reuben 22:06, 10 September 2007 (UTC)

which is the largest flower?

• email removed to prevent spam* —Preceding unsigned comment added by 59.92.30.8 (talk) 10:23, 10 September 2007 (UTC)

Probably Rafflesia arnoldii? --antilived 10:25, 10 September 2007 (UTC)

Or perhaps Amorphophallus titanum? Capuchin 10:30, 10 September 2007 (UTC)

• No, Antilived had it right. The thing that looks like a flower on the A. titum is actually a spadix (a stalk for holding clustered flowers which have no pedicles) surrounded by a modified leaf called a spathe. The actual flowers are arrayed in their thousands deep down in the spathe. Here are some pictures of them after having been pollinated: . --Sean 18:14, 10 September 2007 (UTC)

what is the phenolics of lemon grass

what is the phenolics of lemon grass —Preceding unsigned comment added by 210.213.146.100 (talk) 10:48, 10 September 2007 (UTC)

Did you look at Cymbopogon? --Mdwyer 20:46, 10 September 2007 (UTC)

Distance travelled by the Space Shuttle

Space Shuttle Endeavour has flown 19 flights, spent 206.60 days in space, completed 3,259 orbits, and flown 85,072,077 miles (136,910,237 km) in total, as of February 2003.

What does this mean? How is this distance calculated, given that at some point the vehicle leaves Earth's atmosphere and enters orbit, involving a change of context - technically, it was already travelling at 900 miles per hour (0.4 km/s)while on the ground, but at some point we consider it to be "travelling". When does this change take place?

For example, if I am on the ground, I am stationary. If I hover 10m above the ground, then I am still stationary. If I hover a mile above the ground, most people would say that I am still stationary. If, however, I hover 35,786 km above the ground, then I am travelling at 3 km/s in geostationary orbit. When does this change take place? How far up do you have to be to be considered moving as against stationary?

For a spacecraft like the shuttle, you could just measure the distance travelled since take-off, and count the motion gained from the Earth's rotation as a bonus. However, in a more general case of measuring space travel, the Earth is travelling around the sun at 30 km/s. A craft that leaves Earth orbit and goes around the sun independently is then considered to be going considerably faster than it was when it was in orbit.

I think the question of "how far has a spacecraft travelled" is even more meaningless than "how long is the coastline of mainland Britain". It all depends how you measure it, there is no "correct" answer.

— PhilHibbs | talk 12:31, 10 September 2007 (UTC)

It's only meaningless if you don't define your terms carefully enough. The addition of the five words "relative to it's launch pad" to the question would be sufficient to give you a very clear definition of what is meant with a nice, simple, unambiguous answer. For the shuttle, that's actually a fairly useful and meaningful definition - and is almost certainly what is intended here. But if you were thinking of one of the Apollo moon missions, it would be less obvious that this makes sense because all the time the LEM was parked on the moon, it would be racking up miles relative to Houston without "moving" at all (relative to the moon). Without some kind of qualification, you can't talk about the distance that anything travels. The odometer on your car fails entirely to measure the distance travelled by the body of the car relative to you - or relative to the moon - or relative to it's own gear shifter knob for that matter. When we talk about distances travelled, we generally assume we're talking about 'relative to some fixed point on the surface of the earth' - this convention only starts to break down when we're talking about spacecraft and such. "How long is the coastline of Britain?" is a MUCH harder concept to pin down. SteveBaker 17:19, 10 September 2007 (UTC)

So you'd expect that distance to be relative to a point on the earth. That would mean that its speed relative to the launch pad is constantly changing as it passes over it and goes round the other side of the world. The constant change of speed relative to the launch pad would make measuring the distance travelled very difficult. I'd expect that at some point they disregard the launch point and start measuring distance travelled relative to the centre of orbit, as circular paths are a lot easier to calculate than the twisty turny loopiness of a path measured relative to a rotating starting position. Maybe I'm wrong, and the start point adjustment is just a single matrix transformation applied to the velocity. — PhilHibbs | talk 11:06, 11 September 2007 (UTC)

Don't confuse 'speed' and 'velocity'. Velocity is speed+direction. The velocity of the shuttle does indeed change continually with respect to it's launchpad as it orbits. But it's speed doesn't change much in a stable circular orbit. In an elliptical orbit, yes, the speed changes - but the shuttle isn't normally in anything very far from a circular orbit. The calculations involved in changing the place you are measuring distance relative to are pretty trivial. I could do it with just a handful of lines of computer code (given a suitable math library - which you can be sure NASA will be using). But "distance travelled" isn't really important to either the navigation of the shuttle itself or it's controllers on Earth - these kinds of statistics are really only there to impress the press corps (who are easily impressed!).

Doing some 'mathematical archeology', my guess is that they are simply taking the number of orbits - which they know exactly (3259) and multiplying by the circumference of a 'typical' circular orbit. I guessed that they'd calculate that from the mean equatorial radius of the earth plus 300km as a 'typical' orbital altitude (the shuttle can orbit anywhere between 185 and 1000km altitude - but 300km is typical because that's roughly the altitude of the ISS). Multiply that out and if you pick the right approximation for PI and the right approximation for the mean equatorial radius of the earth and round the result to the nearest million kilometers and by an AMAZING coincidence, you get 137,000,000km - which is almost exactly what you quoted above.

This means that it's almost certain that the figure you have is a horrible approximation. They did the exact same very rough 'back of envelope' calculation based on the number of orbits and a guesstimate for the mean altitude. Since they count orbits relative to the launchpad, that distance travelled is (very roughly) the distance travelled relative to the launchpad. QED. The only horrifying thing here is that they unscientifically quoted the result to 9 significant digits. They should have said: "About 100 million kilometers" given the way they probably did the math. SteveBaker 14:13, 11 September 2007 (UTC)

And here we have the reason I asked this question. Should a "horrible approximation" be presented as fact in an encyclopedia? Misplaced Pages isn't in the business of impressing the press corps. But this has strayed beyond the scope of the Reference Desk, this is a topic for the Talk Page. — PhilHibbs | talk 09:30, 12 September 2007 (UTC)

Well, for the purposes of the encyclopedia, it is enough to say who says that this is the case and provide a reference. "NASA says that...yadda, yadda." is OK because you are documenting the fact that they claimed this - not that Misplaced Pages necessarily believes it to be true. Personally, I'd round off that number though. Giving the answer accurate to the nearest klick out of 137 million is ridiculously precise and more or less guaranteed to be wrong. SteveBaker 14:59, 12 September 2007 (UTC)

Roundness

Why when you take everything down to atoms is everything round? From soap bubbles to stars to elctrons to the universe. Why is it all round? 89.240.69.176 14:54, 10 September 2007 (UTC)

The sphere is the only shape that looks the same from every direction. —Keenan Pepper 14:57, 10 September 2007 (UTC)

Who said electrons are "round"? Or the universe for that matter? And atoms don't really have a shape either; their wavefunctions stretch outward forever. --Spoon! 15:23, 10 September 2007 (UTC)

And if you did have to assign a shape to an atom, it would most likely not be spherical. The electron cloud is described by the atomic orbitals, some of which have quite unusual shapes, not just a huge non-descript blob of "all electrons spread around the nucleus". DMacks 16:34, 10 September 2007 (UTC)

Circles and spheres are efficient in many natural processes. Check out the On Being Round lecture by Neil deGrasse Tyson (also available in his books and DVDs, though they are a bit pricey.) Weregerbil 16:26, 10 September 2007 (UTC)

Among all solid shapes, the sphere has the smallest ratio of surface area to volume (same applies to circles when you're talking about 2 dimensions). A circular orbit (be it planet or electron) is the shortest orbit with the most constant velocity. If an object (or wave) expands equally in every direction, it makes a sphere (or circle... picture the ripples in a pond). --SB_Johnny | 16:33, 10 September 2007 (UTC)

The question is, why isn't something round? If there are no particular features to make something have a corner or a side, it ends up round. Gzuckier 17:40, 10 September 2007 (UTC)

I have to say that diagrams/pictures of what objects look like do seem to reduce everythign to being circle/spherical...Search electron in google image search - the first page is virtually all spherical shapes. The same is true for atom, and also proton. If these images are not what things actually look like even in their simplest shape then you can see where the confusion would lie. Certainly I was under a similar impression to the original questionnaire - everything looks like spheres connected with cylinders in the minature world...at least artists impressions do! ny156uk 19:44, 10 September 2007 (UTC)

That's a huge problem, and one that can't really be solved well. A real danger I see in my classes is when people think one explanation or one model is the complete and exact picture of something. What subatomic things "actually" look like often isn't known and sometimes can't be known, often doesn't matter, and sometimes doesn't even actually exist. But we can still talk about them and describe them and draw them. We can draw them many different ways and make many different sorts of models of them, each way illustrates certain properties well, but is not useful (and sometimes very misleading) if one uses it to illustrate things for which it wasn't designed. A paper airplane sorta looks like an airplane and it flies, but there's nowhere to put luggage, but you wouldn't say "therefore real planes generally don't have luggage compartments". Drawing an atom as a circle or dot, and electrons as dots or circles around a nucleus does give a good general idea of what and where things are. If someone says "draw it", then you gotta draw something, and if you need to talk about the relative positions of two things, you need to draw "two things". So best we can usually do is to draw a circle or a blob. DMacks 14:44, 11 September 2007 (UTC)

downloading something to a persons brain

is it possible that something like a new language can be downloaded to the brain of someone as waves a brain can understand , which will possible make him learn something new easily ????? —Preceding unsigned comment added by 212.107.116.238 (talk) 15:29, 10 September 2007 (UTC)

Save it for the future...128.163.170.178 15:39, 10 September 2007 (UTC)

I don't have sources, but no, I do not think it is possible, yet. It will definitely be possible in the future, as it doesn't break any laws of nature. — Adriaan (T★C) 15:47, 10 September 2007 (UTC)

Probably not (or at least not for a long time). Brains "grow" their knowledge in a sense by making or modifying physical connections between neurons. It's a bit more complicated than changing the polarity of magnets to make 1s and 0s like we do in computers. --SB_Johnny | 16:37, 10 September 2007 (UTC)

FYI, the theme is explored in film The Matrix, the short story/film Johnny Mnemonic (short story)/Johnny Mnemonic (film), and the short story/film We Can Remember It for You Wholesale/Total Recall, as well as the Star Trek episode "Spock's Brain".

Atlant 17:14, 10 September 2007 (UTC)

I think the problem is that the memories within a brain are made up of connections between cells. The way those connections form is different for everyone. To take a wild (but true) example - I'm British - before I came to America I had no need to know which US political party was which. I arrived here during the Clinton impeachment stuff - and I remembered that Clinton was a democrat because 'democrat' sounds a bit like 'DAME-o-crat' (dame==woman, woman==reason for Clinton's impeachment) and the opposition were behaving weirdly - like they were drunk or something - so I formed the connection "re-PUB-lican"...weird - but for a while that was how I recalled which was which. Now I have some brain connections that associate those things together. I'm fairly sure that nobody else made that same set of connections - everyone has a different means to remember facts like that. Hence to teach someone something (like perhaps to teach me which US presidents were with which political party), you'd first have to understand how all of their knowledge fitted together - then develop some kind of custom neuronal re-wiring that would be unique to that person. It's also likely that learning one thing changes your perception of other things. It might be exceedingly dangerous to have a machine teach you something because it could easily mess up what you've already learned. This seems exceedingly difficult - even in a sci-fi setting. It's tough to say it would be impossible though - as Adriaan90 said - no physical laws seem to need be broken to make this happen. SteveBaker 17:32, 10 September 2007 (UTC)

Another way might be to add external memory (be it electronic or biological or whatever), let's say in the form of a helmet, to make connections short (an 'even neo-er cortex', let me call it the neoneocortex). But for that to work instantly, the brain of that person would have to be intricately analysed, at least the parts that deal with whatever knowledge you're adding. If those can be localised, that is, because a specific bit of knowledge is not in one specific place. Knowledge is not localised, it consists of connections between other pieces of knowledge, which in turn are just connections between yet other pieces of knowledge (I think that's what Steve meant to say). What is more feasible is to just make some connections between the 'two brains' and let them work out the right connections themselves through learning. In which case you're back to square one - the person still has to learn it the old fashioned way, he just has more brainpower. But this opens another avenue. What if it were seen not as an extension, but as an interface. On one side it talks to the original brain and on the other side to a computer. Then, at a conscious level, the person could download info to the computer and then absorb it on a subconscious level through the neoneocortex. Note that those are both actions of the brain, with higher levels helping lower levels through the use of a tool. DirkvdM 07:06, 11 September 2007 (UTC)

Communicating with animals ??

animals produce sound waves that probably they understand but we humans dont, so it is possible to make a convertor that can converts animals sound waves to understandable sound waves to humans ??? —Preceding unsigned comment added by 212.107.116.238 (talk) 15:32, 10 September 2007 (UTC)

How we experience what we're communicatiing might be so different that the signifiers would make little sense. See qualia for some discussion. --SB_Johnny | 16:39, 10 September 2007 (UTC)

Are you asking if it's possible to modify inaudible sounds so that we can hear them? Then yes, I think whale songs often need to be adjusted before humans can hear them. If you're asking if it's possible to translate animal 'language' into human language, the answer is typically 'no' because most animals don't have a structured language, but check out Waggle Dance 69.95.50.15 17:55, 10 September 2007 (UTC)

I think we understand some animal "languages" just fine. We all know that when a cat is happy it purrs and when it's upset it yeowls and so forth. My dogs use a very particular 'hurt puppy' yap when they want to be let back into the house from the back yard and big deep barks when they are trying to scare off people who come up to the front of the house. They use distinctive body language too - who can mistake the big side-to-side wag (meaning "welcome") and the smaller wag (meaning "happy") and the front-end-down, rear-end-up-in-the-air (a "play bow" - meaning "What is about to happen is all for fun!")? There is even a sense of 'word order': A play bow followed by growling means something very different from a deep bark followed by growling. Barking+Tail wagging means something different from barking whilst jumping up and down with fore-feet only (which indicates frustration and a need to rush off and do something). I think we can learn and understand the language of familiar animals just fine. We know that cat's wag their tails when they are annoyed and dogs do it when they are happy (this explains a lot about why cats and dogs don't always get on very well!) You are assuming that what they are saying is a lot more sophisticated than that...but it's not - most animals are simple creatures with simple communication needs that they have evolved to deal with. SteveBaker 18:46, 10 September 2007 (UTC)

That very last bit ('evolved') goes against the bit just before it ('simple'). Along the lines of what SB_Johnny said, they evolved in a different mindset and therefore speak (or communicate in whatever way) about very different things. Sort of like Eskimos having 20 words for snow, just taken much further. The only common grounds we have are basic things like anger and joy, as you described for your dog. Dogs don't understand most things we say, so we think they are stupid, but the reverse might also be true. So how do we find that out? Maybe a mind merger with the neoneocortex I described above, one for us, one for the dog? DirkvdM 07:33, 11 September 2007 (UTC)

We might not be able to understand what they're thinking, because their brain is structured differently (ever read Thomas Nagel's essay, "What is it like to be a bat?") That doesn't mean that other animals have a complex language we simply don't understand. We can study a dog's brain and vocalizations and come to the conclusion that there is no complex speech behavior. -- JSBillings 20:39, 11 September 2007 (UTC)

How does/does this theory apply to talking parrots, as a matter of interest? --Kurt Shaped Box 23:39, 11 September 2007 (UTC)

As far as I know, the parrot mimics the sound, but does not usually comprehend the meaning of the words. Nimur 17:01, 12 September 2007 (UTC)

Hire a consultant. I recommend Dr. Doolittle, if he's available.--Eriastrum 16:48, 12 September 2007 (UTC)

I don't know if there has been extensive studies of parrot (or other bird) speech centers, so I couldn't comment. I'm just saying that in the case of User:DirkvdM's comment, it is possible to determine if there is complex speech by studying behavior and brain imaging. -- JSBillings

Cloning Machine ?

is it possible to clone an apple for example by a machine, as a begining we add all the elements the apple made up of and place it in a machine , then give the machine the information of how these element are joined or made up , and then the machine uses this information and elements to make an identeical apple ??????? —Preceding unsigned comment added by 212.107.116.238 (talk) 15:36, 10 September 2007 (UTC)

Again, I don't have sources, but no, I do not think it is possible, yet. It will definitely be possible in the future, as it doesn't break any laws of nature (or does it? can't think of any). — Adriaan (T★C) 15:48, 10 September 2007 (UTC)

Impossible for now or in the foreseeable future. The field of organic chemistry, where chemists make compounds found in nature (and compounds inspired by those in nature), has been able to make complex molecules--but many molecules that are diagrammable on paper are still impossible to make due to their complex bondings and unknown reaction mechanisms. An apple consists of millions of cells, and each cell contains millions of such complex molecules, that it's practically impossible to make a machine like the one you described. It would take us not only a complete knowledge of reaction mechanisms, but also a machine that can do things in detailed 3-dimensional molecular level. I say it would never happen. 128.163.170.178 16:22, 10 September 2007 (UTC)

It's certainly utterly impossible to create a perfect replica. For that you'd need to measure the position and speed of every electron and every atomic nucleus in the apple simultaneously and you can't do that because of the uncertainty principle. So we know for 100% sure that this is going to be a less-than-perfect copy (although perhaps it would be flawed in some way that we don't particularly care about - perhaps we didn't catch all of the vibrational modes of all of the atoms - so the temperature distribution in the copy is a bit incorrect). So if we admit that the copy only has to be good enough to fool the average person - perhaps it would suffice for the machine to analyse a single cell of the flesh of the apple, some representative cells from the skin, the pips, the stalk, etc - then to simply fill the volume of the flesh with identical copies of that one cell, coat it with a representative number of skin cells...and so on for all of the major structures of the apple. This (whilst still an exceedingly daunting task) would at least put the data capacities and bandwidths down to something conceivable at some time in the far distant future. There are still problems though. Assembling all of these structures atom-by-atom will take time - and during that time, some parts of the newly forming apple that have never been exposed to the air in the apple we are copying would indeed be exposed to the air in the copy (and no - doing it in a vacuum wouldn't help either). If you (say) started off by making the skin of the apple - it would collapse long before you could make all of the flesh inside. If you made the flesh first, it would start to go brown in the air before you could get the skin onto it. So it wouldn't be the same. You can't assemble the copy infinitely rapidly - and that's a problem. So this is another one of those ideas that seems reasonable in theory - but which has such an astronomical number of practical problems that seem insurmountable. —Preceding unsigned comment added by SteveBaker (talk • contribs) 17:48, 10 September 2007 (UTC)

• See also No cloning theorem for more pessimism on this topic. --Sean 18:30, 10 September 2007 (UTC)

Also see 3D printer for something that can do a similar thing inorganically. -Wooty   01:03, 11 September 2007 (UTC)

A 3D scanner - coupled (via some fairly heavy computational stuff) to a 3D printer could reproduce the external form of an object to some degree of precision - a fraction of a millimeter for the best ones. So you could certainly (today) scan an apple then make a plastic model of an apple that was more or less the same size and shape. If you used something like a CAT scanner that can image the interiors of things - then the 3D printer could make the pips inside the apple. Some 3D printers could even make the skin, the flesh and the pips be roughly the right colour - but you can't "scan" the colours of the insides of things with any technology we have right now (or are every likely to have) without slicing up and destroying the object you are scanning. However, you most certainly cannot use a 3D printer to print an apple that you'd be able to eat - or plant into the ground to grow a new apple tree from - so in that sense, you can't reproduce an object like that. If course if the object you are copying were made out of the same kinds of plastics that your 3D printer is using then perhaps a reasonably exact copy could be made using these techniques. SteveBaker 13:37, 11 September 2007 (UTC)

One of the goals of the RepRap Project is to create a 3D printer that can fabricate each of its own parts. Not quite self-replication, however, as these parts would still have to be assembled to create a duplicate printer. Gandalf61 13:53, 11 September 2007 (UTC)

Plus there are a heck of a lot of parts that the RepRap won't be able to replicate - motors, computer chips, nuts and bolts, threaded rod, etc. SteveBaker 15:00, 11 September 2007 (UTC)

The term "clone" when applied to organisms usually means that another individual is made that has an identical genome. We do that all the time for apples (the plants, not the individual fruit) and thousands of other plants. Any plant multiplied by vegetative reproduction (usually by cuttings or grafting) results in clones of the original plant. This is what cultivars are. Thus if you buy a 'Red Delicious' Apple you are acquiring a clone of the original Red Delicious. The original poster used the term "clone" in the sense of making an exact, atom-by-atom replica of a particular piece of fruit. As pointed out above, this is, of course, impossible. I don't think that "clone" defined as a replica is the usual definition, although meanings do change over time. What do the rest of you think about using the word "clone" in this sense?--Eriastrum 17:05, 12 September 2007 (UTC)

Wiktionary says:

1. A living organism (originally a plant) produced asexually from a single ancestor, to which it is genetically identical.
2. A copy or imitation of something already existing, especially when designed to simulate it.

So I think both meanings are OK - it was just unfortunate that the second meaning was intended when the object (being a plant) could easily be cloned (meaning the first meaning). However, the form of the question shows that the OP clearly intended the second meaning. SteveBaker 17:31, 12 September 2007 (UTC)

Acid rain effect on churches

Dear Sir/Madam,

I am looking for pictures that clearly illustrate the effect of acid rain on churches, Plus a brief simple explanation of why for my 15 yr old son

Thanks for your help

Happy Monday

Graham —Preceding unsigned comment added by 81.247.197.62 (talk) 16:19, 10 September 2007 (UTC)

Our article on acid rain has a few pictures, I don't see one of a church though. There is an image of a statue damaged by acid rain in that article. Splintercellguy 16:57, 10 September 2007 (UTC)

(Although I haven't tried it,) A Google search for "Gargoyle acid-rain" will probably reveal something.

Atlant 17:17, 10 September 2007 (UTC)

I don't know about churches - but the most clear example I can think of is the Caryatids in Erechtheum in Athens. These are female figures that support the roof of a temple of some kind. One of the Caryatids was taken by the British in the early 1800's (before acid rain was a problem) and kept safe indoors and in museums. The remaining Caryatids had to suffer the worst of Athen's pollution. Compare the sharp/well-defined carving in the leftmost photo of the Caryatid kept in the museum versus the smooth rounded-off ones that spent nearly 200 years in Acid rain on the right. (Actually, the one in the second photo is a replica - the originals having FINALLY been taken into protective storage to prevent further damage - but it is an exceedingly good copy). Look particularly at the details of the faces! You might argue that 200 years out in the rain and other weather did this - not acid rain - but recall that both the statue in the museum and the ones still outdoors had been there since 400BC. So the indoor one shows 2200 years of weather + 200 years in the museum and the outdoor ones suffered 2400 years of weather. The amount of weathering due to rain is therefore almost identical in both cases - but the last 200 years made all the difference. This is the clearest example of how modern pollution affects stonework because we can see what the objects would have been like had they not been exposed to it. SteveBaker 18:09, 10 September 2007 (UTC)

Acid rain is a big problem for buildings made of limestone, as many statues, monuments and churches, certainly in the UK and probably elsewhere, are. Limestone is made of calcium carbonate, which is also used as an antacid. When a carbonate meets an acid, the carbonate reacts to form water, salt and carbon dioxide gas, which weakens the limestone. You can see this effect for yourself if you put a few drops of a weak acid like vinegar or lemon juice onto an antacid tablet: the antacid begins to fizz as the carbon dioxide gas is released, and then crumbles until you are left with just a sludgy residue - the same effect is happening with limestone buildings, just much slower. Laïka 10:39, 11 September 2007 (UTC)

Can changes in proportions of oxygen in our atmosphere affect combustion?

I've heard that the ratio of oxygen to inert gas in earth's atmosphere is finely tuned: that a greater proportion of oxygen would enable global incineration, and that a lesser proportion could make combustion impossible.

In my explorations of combustion and atmosphere on Wiki, I see no mention of anything like this. I'm attempting to help a friend with a sci-fi story idea, and need to know more about this. Do noble gases play a role in combustion in our atmosphere? Would an increase in argon or xenon affect combustion?

Thanks 216.151.17.169 17:31, 10 September 2007 (UTC)

I've heard the same thing; it's part of the Gaia hypothesis, although our article doesn't seem to touch in that facet. Where I remember reading about it is in James Lovelock's Gaia book, where it's discussed at some length --Steve Summit (talk) 17:52, 10 September 2007 (UTC)

See Earth's_atmosphere#Evolution_on_Earth for some discussion. Speculation: I would think that a highly combustible atmosphere would be self-limiting, as each little spark would burn off enough O2 to get it back down to a reasonable level. --Sean 18:34, 10 September 2007 (UTC)

The noble gasses (which used to be called 'inert gasses' when I was in school) are inert - they don't react with anything (almost). So they are not implicated in this process. (The Gaia thing is pure pseudo-science though - ignore it!) Oxygen forms a balance with plants chucking it out and animals and combustion eating it up. It appears that magically the density of oxygen is just perfect because anything that would spontaneously combust at this density has ALREADY combusted and there is none of it left. There is no free hydrogen in the atmosphere because as fast as it forms, it gets combusted into water. Ergo, whatever is left is things that don't spontaneously combust at this oxygen density. No magic - no "The planet is a life-form called Gaia" - just basic chemistry. SteveBaker 18:35, 10 September 2007 (UTC)

Hydrogen is the ninth most common gas in the atmosphere, so "none" is an overstatement. 76.231.189.193 16:09, 11 September 2007 (UTC)

Here's one of a set of lecture notes from the University of Michigan called Evolution of the Atmosphere. According to this class: "Why does present-day oxygen sit at 20%? This is not a trivial question since significantly lower or higher levels would be damaging to life. If we had < 15% oxygen, fires would not burn, yet at > 25% oxygen, even wet organic matter would burn freely." --Reuben 18:52, 10 September 2007 (UTC)

But that's the point. If there was <15% then animals would start to die off and things wouldn't burn - so the oxygen produced by plants would not be consumed as quickly as it is now. The oxygen density would then build up until animal life could recover and things would be able to burn again - to the point where the amount of oxygen produced equalled the amount consumed - probably at around 20%. If there were 25% oxygen and vegetation would burn much more easily - then we'd have a huge increase in the number of forest fires, etc - and these would consume oxygen until it fell back to the point where those fires would cease to happen...right around 20% probably. It's a feedback system that maintains stability at a particular point. SteveBaker 19:31, 10 September 2007 (UTC)

Which is, of course, exactly what the Gaia hypothesis is really about. The whole 'life-form' thing is like Le Chatelier's principle. Skittle 23:08, 11 September 2007 (UTC)

That's an interesting speculation, but it doesn't always appear to have worked that way. From the same lecture notes:

According to recently developed geochemical models, oxygen levels are believed to have climbed to a maximum of 35 percent and then dropped to a low of 15 percent during a 120-million-year period that ended in a mass extinction at the end of the Permian. Such a jump in oxygen would have had dramatic biological consequences by enhancing diffusion-dependent processes such as respiration, allowing insects such as dragonflies, centipedes, scorpions and spiders to grow to very large sizes. Fossil records indicate, for example, that one species of dragonfly had a wing span of 2 1/2 feet.

so I would want to see some evidence that such a feedback cycle actually operates. --Reuben 19:34, 10 September 2007 (UTC)

Here's an article that ties together two recent reference desk threads: R. Dudley, Atmospheric oxygen, giant Paleozoic insects and the evolution of aerial locomotor performance. Journal of Experimental Biology, Vol 201, Issue 8 1043-1050. --Reuben 22:06, 10 September 2007 (UTC)

The evidence for such a feedback cycle is that it makes perfect sense. But that does not mean there are no other factors. Something else could thrown it completely off balance. So maybe something caused a mass extinction of animals, which led to a sudden rise in the oxygen level, which led to a mass extinction of plants, which led to a massive drop in the oxygen level. In other words, a chaotic system that eventually finds its balance again. Note that I have absolutely no factual knowledge in this field and I probably misused the term 'chaotic system'. DirkvdM 08:16, 11 September 2007 (UTC)

Not really. Oxygen levels rose due to excess organic burial in the Carboniferous following the biological invention of chitin. 6 CO2 + 6 H2O <-> C6H12O6 + 6 O2 represents a balance between respiration and photosynthesis. By burying organic matter (i.e. the C6H12O6) before it can be consumed one gradually accumulated an excess of O2 over tens of millions of years. While combustion would become more common it didn't provide much of a control if concentrations can nearly double due to gradual imbalances. 76.231.189.193 16:09, 11 September 2007 (UTC)

I don't get that last bit. Over millions of years, even evolution could have reacted by putting more oxygen-consuming animals on the planet. Unless something else prohibited that or killed them off. DirkvdM 18:40, 11 September 2007 (UTC)

I read a story by Edgar Allen Poe that has the Earth intersect the orbit of a comet consisting almost entirely of oxygen. For a while plants start growing like wild, but at a certain point the entire Earth combusts. Pretty cool.BungaDunga 01:09, 12 September 2007 (UTC)

Good one. The Conversation of Eiros and Charmion. --Reuben 01:17, 12 September 2007 (UTC)

electronics and communication

can some one help me out in telling me how does the the information transmission take place in wireless communication.what methods r used to modulated a signal and what is the method for the reconstruction of the original signal. is the wireless transmission take place as a analog or as a digital way? —Preceding unsigned comment added by Kamuali (talk • contribs) 18:28, 10 September 2007 (UTC)

You asked this question ] and got some good responses. You should read those articles (radio, modulation, etc.) and ask questions about those if you have them. --Sean 18:37, 10 September 2007 (UTC)

Gray Hair

Why does gray hair not only lose pigmentation but also turn wiry? --WonderFran 18:46, 10 September 2007 (UTC)

Presumably it is losing its strength and thus becomes more frayed/frail looking. Grey hair might help, that is if that is even an article...ny156uk 18:59, 10 September 2007 (UTC)

In regularly colored hair, melanin is produced in melanocytes around the hair root, and "injected" into hair root cells. Melanin inhibits cell division and promotes the hornification of these cells. During aging, less melanin is produced as the melanocytes die and fail to be replaced. Less melanin means a higher rate of cell division in hair root cells and, consequently, an increase in hair shaft diameter. When you increase shaft diameter the result is wiry hair. Rockpocket 08:27, 12 September 2007 (UTC)

MEDICAL EDUCATION IN CUBA

DEARS, i want an answer of a question related to the medical education in cuba. Does medical education in cuba is up to world level of medical education? How much importance is given to a student who has a medical degree from cuban medical institutes in europe, america and in other parts of world if he wants to study there or wants to job there? what about its curriculum? Is it cmpatible with other courses that are taught in other world universities? Level of practical work ? What about surgery ? Would you like to try to answer mi , if you know, because it is very very importante for mi?

  asifji  —Preceding unsigned comment added by 201.220.222.140 (talk) 20:17, 10 September 2007 (UTC)

Might I direct you to Education in Cuba. Students who have obtained their medical degrees in Cuba have been permitted to practice medicine in the United States. I can't speak for Europe. Someguy1221 20:23, 10 September 2007 (UTC)

Permitted? Of course, why not? Hell, if even the US permits it .... . But I understand the questioneer is asking if a medical study in Cuba is likely to get him/her a job or extended study elsewhere. DirkvdM 08:21, 11 September 2007 (UTC)

The news articles cited in my link, as well as the link itself, suggested that those American doctors who received their degrees in Cuba did all find practices in the United States afterwards. However, it also mentions they worked for low cost healthcare, which might imply low-income jobs. Someguy1221 19:31, 11 September 2007 (UTC)

Douglas-fir in Europe

I would like to know

1. When Douglas-fir tree species only come from North America, Mexico and East Asia, where do the Douglas-firs in Europe come from?
   1. Do they all descend from American trees introduced to Europe? Can they be traced back even to David Douglas himself?
2. I have heard a story that the Douglas-fir became extinct in Europe during the last Ice Age. Is that true?
   1. And if yes, was it of an own species or the same still found today?
   2. Is it known what the distinctive ecological influence in Europe was, that it vanished there but survived in America and Asia, who both had an Ice Age too? --Vancouver robin 21:26, 10 September 2007 (UTC)

Cells

what are the functions of cells ? —Preceding unsigned comment added by 69.122.140.71 (talk) 21:32, 10 September 2007 (UTC)

Howdy, you're question is pretty broad. You might start at the Cell (biology) article, and see if that doesn't answer your question. --TeaDrinker 22:08, 10 September 2007 (UTC)

Or whichever type of cell you are referring to.--Shantavira| 07:39, 11 September 2007 (UTC)

If you're talking about biological cells, well, they're the stuf we're made of. So what functions? All of them. DirkvdM 08:25, 11 September 2007 (UTC)

The functions of cells is life - all of life (except for Viruses - which some people claim are alive and others claim are not). Our article on life says: Growth through metabolism, reproduction, and the power of adaptation. Which is pretty much the function of cells. SteveBaker 13:26, 11 September 2007 (UTC)

Cells also make sure that prisoners do not escape from prison.Mrdeath5493 18:16, 11 September 2007 (UTC)

Says Mr Death ... is 5493 your cell number? DirkvdM 18:43, 11 September 2007 (UTC)

beaver diet

I just read a kids' magazine that says that beavers eat wood. This doesn't seem right to me, since I don't think anything bigger than a termite eats wood. The article mentioned that they store branches underwater to eat during the winter. Misplaced Pages's beaver article mentions wood being stored underwater for building, but I didn't see anything about them eating it. So, do beavers eat wood? And why do they store branches underwater? Couldn't they just cut down a tree whenever they needed it? Thanks Ingrid 22:34, 10 September 2007 (UTC)

http://www.nhptv.org/Natureworks/beaver.htm suggests that tree bark is part of their diet. I would expect they store wood for building because in the winter food may be harder to come by and the energy required to cut down trees/get their wood would be too vast at that time of year? ny156uk 23:25, 10 September 2007 (UTC)

Beavers eat bark and leaves, not wood. They do bring branches underwater to store and preserve for the winter, much like people store crops in root cellars, spring houses or freezers. Come to think of it, an ice-coated pond probably has a similar temperature range to a refrigerator, so perhaps that's the best analogy. They probably don't do much in the way of construction in winter, unless they're in a climate where the pond doesn't freeze. --SB_Johnny | 11:42, 11 September 2007 (UTC) Yikes! check out that root cellar article!

Date of Death

I am not sure how to phrase my question, or even if it is a "science" question, so please bear with me. Thanks. (Perhaps this is a humanities / sociology question? Unsure.) Can anyone offer some entries on a list of advantages versus disadvantages of an individual knowing his precise date and time of death, while being oblivious to the manner of his death? A related question #1: would any of those advantages / disadvantages on the list change if the individual were also to know the manner of death in conjunction with the precise date/time of it? A related question #2: same as above, but for another individual (i.e., not for one's self) -- such as having that info about your spouse/child/sibling/parent/best friend/boss/neighbor/mailman/etc. In other words, I am not trying to take a poll such as "If the information were available to you, would you elect to know or would you elect to not know your date/time/manner of death?" I am asking, what are the factors that one would consider (i.e., the advantages and disadvantages) in order to make such a decision? And what are the advantages / disadvantages to society as a whole and to individuals of having versus not having this information? Assume that the information is 100% accurate and unable to be manipulated (i.e., you can't change it -- it is 100% certain). Thanks. (Joseph A. Spadaro 23:07, 10 September 2007 (UTC))

This isn't a scientific question, but it certainly could be a science fiction question. ;-) It seems to me that the entire thing revolves around the notion of predestination (fate), which is of course against our notions of free will, self-determination, and all that. We all like to think that the future is undecided — and maybe it is — and knowing anything that certain about it, especially something as monumental as our own deaths, definitely throws a wrench into that. Now, of course, we all know that we will die, eventually, but the timing could make a lot of difference: if I were to die tomorrow, would I be doing something which is onerous in the short term (graduate school) but beneficial in the long term? Would I bother making long-term investments in people, places, things? Would my balance of life swing much farther towards "live for today" than "invest for the future"? --72.83.173.248 00:53, 11 September 2007 (UTC)

Well, yes -- and, to that extent, it is essentially a question of psychology (of the individual) and perhaps sociology (of society in general). Thus, perhaps appropriately, a "science" question. (Joseph A. Spadaro 00:58, 11 September 2007 (UTC))

You really can't demand a scientific answer to an impossible and entirely hypothetical question. Clearly, nobody can know the precise date of their death with any degree of certainty (unless perhaps they are literally dying and the answer is clearly "today"). Even if you had a good estimate from your present age, health, etc - and if you stayed at home to avoid car accidents - there could always be a mountain-sized meteor smacking into your house at any time. Since knowing your death date precisely is impossible - how could anyone investigate how an individual might react? At best you're going to get a bunch of non-scientific speculation - and this reference desk is the wrong place for that. But there is an even worse problem here. If by some amazing feat of research, you could figure out this "exact date" - wouldn't the person involved immediately change their behavior? If you know you'll live to be 100 years old - why bother exercising and driving carefully? You "know" you can't die from a car crash or a premature heart attack - so why be careful? This is truly an unanswerable question. SteveBaker 13:21, 11 September 2007 (UTC)

OK. OK. OK. Calm down, Steve. Thanks for the input. But, let me re-phrase here. Actually, this is neither an impossible nor a hypothetical situation. That is -- isn't it rather "common" (for lack of a better word) for doctors to inform terminal patients things along the order of "dear patient, our best medical estimate is that you have X months to live" ...? If I had to re-phrase the question, it might take the form of something like this. Let us assume that a specific individual is given the following information, which is 100% accurate and "fixed" (cannot be changed) -- exact date / time / manner / cause of death. Repeat: This is merely an assumption, that is, a premise to the question. Assuming this set of facts: from a psychological standpoint, what would be the advantages / disadvantages of the individual having / not having access to this information? Also, from a sociological standpoint, what would be the advantages / disadvantages to society as a whole? Psychologically, is it "healthier" to know or not know? That is probably a better re-phrasing of my original question. And, the more I think about it, the less impossible and hypothetical this scenario seems. In the grand scheme of things, 99.999% of us do not, in fact, know the details of our death. Nonetheless, there are a significant number of people who do, in fact, have such details -- on some level or another, in some form or another. Examples: terminal patient informed by doctor that you have X months to live; individual who decides to commit suicide; individual who decides to go shoot up a McDonald's knowing in all probability that the police will eventually kill him; individual planning euthenasia or mercy killing; individual planning a murder; individual who decides to "pull the plug" (disconnect respirator/ventilator/etc.); kidnapping victim who is told by his captor, "I will kill you tomorrow if your parents don't pay the ransom"; individual enters surgery knowing that survival odds are slim; the six Utah (or Ohio?) miners trapped in a mine for weeks and weeks and weeks without rescue; a car crash victim in a remote, desolate area who is pinned down and can't escape; individual who survives the sinking of a ship and floats in the ocean for days upon days upon days with no rescue; individual in a car/plane/train that is about to inevitably crash; etc. etc. etc. Granted, these are extreme cases, in relatively small numbers ... yet, nonetheless, it happens. "Many" people can and do know the time/date/cause/manner of their death. So, no -- it is neither impossible nor hypothetical. The examples I gave are hardly far-fetched ... in fact, they pretty much happen every day of the week. No? Thoughts? (Joseph A. Spadaro 14:27, 11 September 2007 (UTC))

When doctors say that, they are certainly not giving anything like an exact date - it's going to be a WIDE spread "six months to a year" or something. You are saying "what if the exact date is known" - and it can't be/isn't - so how can you possibly expect a reasonable answer. Nobody can POSSIBLY know what this knowledge would do to a person. So the answers you'd get would simply be wild speculation. The cases where it's suicide or something like that - you aren't talking about a person with normal feelings - you are talking about someone who is suicidal. Their feelings are all about the suicide nothing to do with the consequences of having that exact knowledge. Even suicidal people don't have exact knowledge - they could still be run over by a car on the way to buying the poison/gun/noose and most suicides fail on their first attempt anyway. Our suicide article says there are between 10 and 20 million attempted suicides each year - but from their breakdown of successful suicides suggests maybe a million worldwide...so even if you plan a suicide, you only have a 5% to 10% chance of knowing the date of your own death. Sorry - but there is no way you'll get a well-informed, scientifically credible answer to this question no matter how you twist it around because the entire premise of it is impossible. SteveBaker 14:44, 11 September 2007 (UTC)

Steve, thanks for the reply. Hmmmmm. I sincerely do not understand your resistance to my question. Perhaps you are being too literal, or perhaps I was. However, if you read the very first words of my question (above), it says: "I am not quite sure exactly how to phrase this question, so please bear with me." As far as doctors informing terminal patients of their impending death. Yes, at the beginning of the process, it is probably a broad range ("six months to a year"). As the terminal disease progresses, however, I am sure that the "date of death" becomes more certain and fixed, more able to be pin-pointed exactly. I am sure that there are many, many, many cases where doctors say to the patient's family, something like: "You should say your good-byes to your grandmother, I don't think she will make it through the night" (or such). My point is that, at some point in the medical process of a terminal disease (not necessarily at the beginning stages / onset), the doctor can and does estimate a reasonable date of death. (Yes, OK, the doctor will not literally say: "The death is 100% certain to be on May 7 at 10:28 am exactly" -- but you know what I mean.) Furthermore, a patient can wait forever to see a doctor and then, when it is "too late", come in with an advanced stage of the terminal disease. In this scenario, the doctor can estimate more closely than that "six months to a year" broad range -- since the diagnosis is being made at such an advanced state of the terminal disease (i.e., a patient who waits until the "last minute" to visit a doctor, when he feels sick). OK, yes, literally ... I did say "what if the exact date is known" (which you say is impossible). One -- Are you more comfortable if I change the semantics to something like, "what if a statistically sound estimate of the exact date is known" ...? Come now. And two -- I gave several plausible examples (above) where a person can very well reasonably know the details of his death in advance (suicide, murder victim, plane crash, falling off a ship, miners trapped in mine, going in for a risky surgery, etc. etc. etc.). I think those are very plausible things that happen every day of the week in the real world -- hardly far-fetched at all. You also state, quote, : "Nobody can POSSIBLY know what this knowledge would do to a person." Why do you consider this an impossibility? I disagree. All you need to do is find an individual (or 25, or 100, or a thousand individuals) who have indeed experienced the scenarios I have described above and, for whatever reason, lived ... as opposed to died. (Example: All the trapped miners died on day 17 except for one miner. That one miner was rescued on day 18. Which is exactly what happened in that Sago Mine Disaster a few years ago in West Virginia (?), I think. Example: You enter a surgery with a 99% chance of not surviving, but you do survive. Example: A murderer lines up 25 people and shoots them one by one. You are next in line (#26), and the cops kill the murderer at that very moment. Etc. Etc. Etc.) I don't understand why you claim it would be impossible to know what this knowledge would do to a person. All we need to do is talk to / interview / ask the people who have had the experience and who have had this knowledge (i.e., a reasonable and sincerely-held -- but incorrect-- belief that they are to die, but they don't in fact die). You also discuss the suicide situation at length. It missed the point to the extent that I was illustrating that an individual can, with certainty, "know" his exact date/time/manner of death. In any event ... I am befuddled why you think this premise is -- as you say -- impossible. Seriously. By the way, I have not delineated any specific time frame here. Perhaps, you are mis-interpreting the question to apply to "people who know these details years and years in advance". Not necessarily. The time frame might be years in advance or it might only be a brief 1, 2, or 5 minutes in advance. You don't think that the Utah trapped miners, at some point, "knew" that they were going to die? You don't think that some murder victims, at some point, can "know" (and digest the fact) that they are about to die? Any way, respond if you like. I suspect that you and I are talking about apples and oranges, however -- and we are not really on the same page. Hence, two such widely divergent perspectives on the question -- which, granted (and, admitted) was difficult to articulate. At this point, if I had to (yet again) re-phrase, I would say something like: What are the psychological advantages/disadvantages to an individual knowing / not knowing the details of his death? And, is it "healthier" to be aware of or to be oblivious of these details? This is a premise, which I do not consider impossible at all. Perhaps the following "twists" of semantics will bring you on board with me? (1) To the two questions I posed a few sentences back, perhaps add the phrase " ... even if the person has that knowledge only for a brief moment ... " (or such). And (2) We can re-define the word "knowing" as meaning "having a reasonable and sincerely-held belief, whether such belief ultimately proves to be correct or incorrect" (or such). Maybe those semantics will clarify my question better? Thanks. (Joseph A. Spadaro 15:32, 11 September 2007 (UTC))

To take these 'examples' one by one:

terminal patient informed by doctor that you have X months to live; - doesn't know the exact date plus or minus six months probably.

individual who decides to commit suicide; - has only a 1:10 to 1:20 chance of actually knowing the date exactly - and even so, this is not someone whom we can study scientifically to get a good answer.

individual who decides to go shoot up a McDonald's knowing in all probability that the police will eventually kill him; - again, this is not someone whom we can study - so we don't know the answer.

individual planning euthenasia or mercy killing; - only knows the date on which someone else will die - not themselves.

individual planning a murder; - ditto.

individual who decides to "pull the plug" (disconnect respirator/ventilator/etc.); - ditto

kidnapping victim who is told by his captor, "I will kill you tomorrow if your parents don't pay the ransom"; - will hold out hope that they'll escape or the random will be paid or that the captor will not carry through. Also, this is another person whom we can't study.

individual enters surgery knowing that survival odds are slim; - Still doesn't know exact date.

the six Utah (or Ohio?) miners trapped in a mine for weeks and weeks and weeks without rescue; - the longest anyone survived a mine collapse is 11 days. They held out hope of a rescue and they didn't know an exact date for death.

a car crash victim in a remote, desolate area who is pinned down and can't escape; - doesn't know the exact date of death and would hold out hope of rescue and we can't study the ones who got the date right!

individual who survives the sinking of a ship and floats in the ocean for days upon days upon days with no rescue; - again, they hold out hope of rescue - don't know when they'll die.

individual in a car/plane/train that is about to inevitably crash; - It's rather hard to ask them their feelings on the matter!

SteveBaker 14:55, 11 September 2007 (UTC)

Hello, again, Steve. I think that our replies "crossed paths" -- so, I am not sure if you saw my immediately preceding reply? I think that we were both typing simultaneously -- oblivious of the other's reply -- and I happened to hit "Enter" a few seconds before you. Anyway ... I read your list of "one-by-one" examples above. I think that you have missed the point of what I am trying to ask. I think that you are being far too literal. Nearly all of your "one by one" examples list (above) focuses on the term "exact date of death". I am not, I repeat not, focused on the "exact" date of death. You keep focusing on that, and I don't know why. And this mis-communication is probably why you are so vehemently defending your point that my premise is impossible. So, for clarity -- I am not concerned with "exact" date of death. As I proposed above, I can play with all sorts of semantics to clarify this. (But I thought that you got the "drift" of what I was saying.) Instead of saying that "a person knows his exact date of death" ... let's say ... "he knows a statistically significant estimate of his exact date of death" ... or ... "he knows his exact date of death with a reasonable degree of statistical probability at the 99% confidence level" ... or ... "he knows his exact date of death within a plus/minus degree of statistical error" ... or whatever semantics will satisfy you. Stop focusing on the word "exact." Think of it this way. In the grand scheme of the question, does it really matter that the miners think / "know" that they will die on Day 18 versus Day 22? No. The number 18 or 22 is not important. The general idea / concept is that the miner is saying to himself: "Geez, within the next 5 or 6 or 7 or 8 days, I will die under the circumstances of x, y, and z." In my immediately previous sentence, the numbers 5, 6, 7, and 8 are not particularly relevent or important to the concept. Rather, it is the concept that: "Wow, I have come to accept the circumstances of my death and I now acccept that my death is inevitable / clearly going to happen / without question ... and whether it is on day 6 or day 8 is not particularly relevent." The second thing you seem to focus on is whether or not, in a practical sense, we can "interview" these people. That is really outside of the scope of the question. In other words, just assume that we can interview them (which, I have pointed out in my previous post, we can in fact do). So, perhaps if you do these two things, then we will be on the same page when reading this question and approaching this topic: (1) remove the literal word "exact" and be satisfied that the person has a pretty "good sense" of the circumstances of his death, plus or minus some statistically insignificant margin of error; and (2) assume that we can interview them -- which we can, in some cases. In reading through your point by point list (above), your focus is on these two issues (1 = we can never truly know the EXACT moment of death ... and ... 2 = even if we could, which we can't, we still cannot access / interview / talk to these people). But, those two points and focuses are misguided and tangential to the question. If you care to, please free your mind of those two thoughts -- accept the premise of the question -- and let me know your thoughts. It's really not that difficult. Is it a good thing or a bad thing ... is it healthy or unhealthy ... is it desirable or undesirable ... for a person to have access to this detailed death information, assuming that somehow such access can be provided? (The degree of detail in the death information is what is bogging you down.) If it helps, re-phrase the question such that a person is XXX % ( say, 95% ) certain of his exact date of death ... or 99% ... or 99.999% ... or whatever number. To placate your concerns for exactness in the date/details of death, we will agree that x cannot equal 100%. Thanks. (Joseph A. Spadaro 16:26, 11 September 2007 (UTC))

Ignoring the difficulties of muggles, I'd say it depends on whether you're thinking of a magical/'advanced science' 'fate-testing' machine which tells you exactly what you'll die of whether it's through violence, accident or health problems, or whether you're dealing with magically accurate medicine that predicts what health problem will kill you and when. With the first scenario I'd imagine you'd get a lot of people who are predicted to die at some much later date becoming extreme risk taker, even trying to 'cheat' the machine by doing ridiculously dangerous things, safe in the knowledge that they wouldn't die. Whether the knowledge given by the machine affects the accuracy would depend on the universe you've picked and how the machine 'works'. With the latter scenario, I'd imagine that people given a long time to live would become excessively cautious, as they believe they have a lot of life to preserve. Those with not long left would probably go through the same things as terminal patients currently do, which there should be studies into for you to read. I'm not convinced that knowing the exact time and day would make much difference compared to knowing 'a couple of weeks' for example, apart from making the situation seem more certain and helpless, but when you're looking at longer time-frames, it could make a big difference.

Socially, I think it would be problematic. Insurance companies, and even employers, would probably be very interested in the results. Medicine could also seem a little depressing when everyone's deathdate is known. With children, why educate the ones that won't make it past 20? Etc.

Sorry not to be more specifically helpful, but I thought I'd try to get the ball rolling again. Maybe someone else has more specifics? Skittle 23:00, 11 September 2007 (UTC)

This Google Scholar search indicates some studies in the general area, although there are a lot of other subjects there too. This sort of thing can certainly be fruitful as a psychology/sociology thought-experiment :) Skittle 23:03, 11 September 2007 (UTC)

This is my reply to the original question. Also see Last Night (a quite good film covering this subject) and Kübler-Ross model (“the process by which people deal with grief and tragedy.” according to Elisabeth Kübler-Ross).
Possible disadvantages:

• Fear
• Panic attacks
• Depression
• Sorrow
• possibly anger
• possibly attempted suicide

Possible advantages:

• having the opportunity to resolve ones worldly affairs.
• having the opportunity to possibly fulfill any religious last rights.
• having the opportunity to prepare one’s self for death.
• the opportunity to tell loved ones any final things.
• being able to think of some really good last words.
• possibly having the opportunity to engage in a few sexual orgies.
• eating anything you want without fear of getting fat.
• telling your boss just what you think of him or her.

--S.dedalus 01:52, 12 September 2007 (UTC)

I also just realized (yet) another example of a plausible (and relatively common) scenario in which an individual "knows" the details of his death in advance ... that is, a prisoner sentenced to execution. In fact, I believe that there is something referred to as "death row syndrome". (Joseph A. Spadaro 05:40, 12 September 2007 (UTC))

Well, yes, except that death row syndrome is very similar in effect to a person being informed by a doctor that they have 'x' months to live. In either scenario the individual is not absolutely certain of their time of death, commutation of death sentences do happen and this would cause a spring of hope in the individual. Richard Avery 08:04, 12 September 2007 (UTC)

Yes, I definitely agree with you -- no doubt. But, again, my original question concerns people who "know" of their death in advance -- not necessarily with 100% absolute certainty -- but 90%-95% (or whatever). Thanks. (Joseph A. Spadaro 15:25, 12 September 2007 (UTC))

Psychology

According to psychologists, strong forces are at work influencing our behavior and the way we lead our lives. Identify three examples of these forces. What are they? —Preceding unsigned comment added by 74.14.119.169 (talk) 23:37, 10 September 2007 (UTC)

Ah, homework question? Start with psychology. --jjron 00:36, 11 September 2007 (UTC)

Electromagnetism, the strong nuclear force, and gravity! Seriously, though, this sounds like a out-of-textbook sort of question. If you can't find the answer there, narrow down the question if possible. -Wooty   01:00, 11 September 2007 (UTC)

Don't forget the weak force! anonymous6494 01:33, 11 September 2007 (UTC)

"The weak force is a strong force at work influcencing our behaviour...". Hmmm. TenOfAllTrades(talk) 02:43, 11 September 2007 (UTC)

Though the weak force is stronger than gravity, of course! Cyta 07:42, 11 September 2007 (UTC)

Wooty meant to put Electroweak instead of electromagnetism (or if he didn't, he should have) :) Capuchin 08:30, 11 September 2007 (UTC)

How do you tell if the weak force is stronger than gravity? They have different units. It's like saying a mile is longer than a minute. — Daniel 22:47, 11 September 2007(UTC)

Surely the main three 'forces' that influence our behaviour are sexual drive, social conformity and social competition. I can't understand why the dicussion is limited to physical forces. Richard Avery 07:47, 12 September 2007 (UTC)

Because people are sarcastically pointing out that we don't do homework for people here, although we may indicate helpful areas. Also that asking vague, textbook-specific questions here won't result in helpful answers. Skittle 11:36, 12 September 2007 (UTC)

September 11

Lift/Drag/Thrust/Weight Diagram

I recall from early physics classes that the classic simplified version of lift-drag-thrust-weight for aircraft mechanics is the first thing that pilots learn about. Yet, I can't find an image or diagram of this model anywhere on Misplaced Pages! I've found some similar versions from a few other websites. I was about to expend some effort to make a nice SVG version similar to this image. Any suggestions or prior work? I found this, but it doesn't show the plane (so it's not very useful for lay-person usage). Nimur 02:13, 11 September 2007 (UTC)

You may also wish to post this at Misplaced Pages talk:WikiProject Aviation. -- Flyguy649 _contribs 02:39, 11 September 2007 (UTC)

If you're looking for a line drawing of an aircraft, there's a whole pile of them on Commons: commons:Category:Aircraft line drawings. Perhaps you could slap the lift/drag/thrust/weight arrows on to one of those? TenOfAllTrades(talk) 02:43, 11 September 2007 (UTC)

Holes in Cheese

This is a serious question; I am curious to know why some cheese has holes and others don't. I would really like a detialed answer with "chemistry", or the chemistry of what happens. Thanks! Phgao 07:21, 11 September 2007 (UTC)

From the article on swiss cheese: "In a late stage of cheese production, the Propionibacter consumes the lactic acid excreted by the other bacteria, and releases carbon dioxide gas, which slowly forms the bubbles that develop the ." --π! 08:04, 11 September 2007 (UTC)

So I would take it that this bacteria produces the holes in all holed cheese? I think I'll do a bit more reseach, and that article http://en.wikipedia.org/Propionibacter_shermani looks like it could do with some work. Phgao 09:34, 11 September 2007 (UTC)

Illness causing hair loss

When I look up "hair loss" in Misplaced Pages, it brings me straight to "baldness". Is it true that extreme illness or stress can cause hair to fall out? Is there a term for this? Are there any particular diseases for which this is considered a common symptom? (Of course, excluding hair loss as a result of cancer treatment.) --π! 08:01, 11 September 2007 (UTC)

Alopecia areata, totalis and universalis? Capuchin 08:04, 11 September 2007 (UTC)

I meant, something that's not usually considered simply "baldness". Losing hair as a side effect as another disorder, not specifically a hair-loss disorder. --π! 08:09, 11 September 2007 (UTC)

Sorry, I don't understand, you're looking for "baldness" that is not "baldness"? Capuchin 08:14, 11 September 2007 (UTC)

You might want to use some of these symptom search engines and see if they come up with anything. I can't as i'm at work: Capuchin 08:20, 11 September 2007 (UTC)

Aha, WebMD had some good answers! Hair loss can be a symptom of: "mental or physical stress, such as recent surgery, illness, or high fever", "poor nutrition, especially lack of protein or iron in the diet", ringworm of the scalp, thyroid disorders, lupus, syphilis, cancer, and hormonal changes. --π! 10:37, 12 September 2007 (UTC)

And I didn't notice it in the baldness article before, but the scientific name for hair loss caused by stress is telogen effluvium. --π! 10:43, 12 September 2007 (UTC)

Re Capuchin - I assume Pi is talking about things that generally cause temporary hair loss rather than permanent baldness, for example chemotherapy typically leads to temporary baldness, but the hair usually grows back once the treatment stops. --jjron 08:23, 11 September 2007 (UTC)

From alopecia areata: "About 50% of patients' hair will regrow in one year without any treatment." Capuchin 08:34, 11 September 2007 (UTC)

I saw hair loss with lupus once.Polypipe Wrangler 11:30, 12 September 2007 (UTC)

Incidence of brain tumours

Is the incidence of brain tumours in the developed world increasing, and if so, what theories have been advanced to explain this? Our article mentions increasing incidence of brain tumours in children, but doesn't say anything about adults. --Richardrj 08:18, 11 September 2007 (UTC)

There are two possible reasons: either 1) our capacity to diagnosis brain tumors is increasing and we're now picking up more tumors than we were previously able to, or 2) the actual incidence of brain tumors is increasing. The fact that humans are living longer and that age predisposes to cancer supports the later argument. An argument for the former is that recent advances have allowed for improved diagnosis (eg, MRI and CT) and classification (eg, widening criteria necessary for diagnosis) of tumors, including brain tumors. This article expands on that argument, noting that the incidence of some "not otherwise specified" primary brain tumors have gone down while the number of more specific diagnoses for primary brain tumors has increased. There are plenty of hypotheses out there that specific chemicals are responsible for an actual rise in brain tumor incidence, but I don't know of any epidemiological studies that have made any good conclusive arguments (then again, I haven't really looked). --David Iberri (talk) 20:08, 11 September 2007 (UTC)

I agree. Everyone dies of something. If we wipe out a disease - or make cars safer or have better law enforcement to reduce the murder rate - then INEVITABLY something else increases in prevelance because in the end the total of the probabilities of dying from all possible causes adds up to 100%. Cure cancer and everything else increases in probability. A better measure would be the average age of people with the disease. If that's decreasing then you have a real problem. If it's increasing then we probably shouldn't worry. SteveBaker 14:47, 12 September 2007 (UTC)

So, what is the average age of people with brain tumours? And is it increasing or decreasing? There must be statistics on this somewhere. --Richardrj 21:12, 12 September 2007 (UTC)

Birthrate skewed towards males?

This newspaper article suggets that even in industrial countries birthrate is skewed towards male offspring. I would have thought it would be 50/50? Why is this the case? http://news.ninemsn.com.au/article.aspx?id=294933 Quote, "the ratio in industrialised countries is 107 to 104 boys for every 100 girls." Phgao 10:49, 11 September 2007 (UTC)

Males die younger. I think nature strives for somewhere around 50:50 after "corrections" (probably 50:50 at childbearing age or something). Capuchin 10:52, 11 September 2007 (UTC)

see Sex ratio --Spoon! 13:15, 11 September 2007 (UTC)

One reason I've heard given is that in a society where children are at high risk of dying, it makes more sense to produce lots of females, which boosts the birth rate at the cost of genetic diversity (few males producing many children narrows the gene pool), while when most children survive to reproduce, there is no need to produce more than about 1 child per person (2 per couple, hence the classic 2.4 children concept). As a result, this society needs fewer females and more males, which will then increase the gene pool and reduce the incidence of genetic disorders. Incidentally, one cause of the high male-female ratio is that in both India and China, the largest centres of population in the world, boys are more highly regarded than girls and, with China's one child policy especially, families may choose to selectively abort female babies or not report the birth to the authorities, thus allowing them to try again for a boy. Laïka 13:26, 11 September 2007 (UTC)

looking at it from the other direction, "female" sperm carry an x chromosome, "male" sperm carry a y chromosome. The y chromosome is a lot smaller than the x chromosome, and the sperm is such a stripped down little hot rod that it makes a difference in its speed, so that "male" chromosomes have a better chance of being the first at the finish line, i.e. the ovum. Gzuckier 16:04, 11 September 2007 (UTC)

Several obvious problems with that including that evolution wouldn't have allowed the such a travesty of an imbalance to have survived so long, and also it doesn't account for why this only applies to to certain countries, especially seeing as most are skewed towards females, notably Russia which had, and apparently still has, a massive imbalance towards females caused supposedly by food shortages. Combined with the reasoning above and that, females intrinsically seem to be smaller and naturally less active than their male counterparts, and more likely to survive in a food shortage. ΦΙΛ Κ 18:28, 11 September 2007 (UTC)

I wish I had a reference for this, but I have heard this discussed on more than one radio show (NPR, not Rush Limbaugh), and if I remember correctly there was something about the pH of the vagina and uterus being governed by stress hormones, which apparently can have some effect on the survival rate of x-carrying and y-carrying chromosomes. (some more about that here, try googling "sperm gender pH acidity selection" and you might find more. --SB_Johnny | 19:44, 11 September 2007 (UTC)

Thanks for the responses! I think there should be a distinction made; yes it is true that in china the male/female ratio is skewed, but that doesn't explain why the *birth* male/female ratio is slightly skewed, as is said in the article above. That is to say the birthrate even in industrialised nations is around 105boys per 100girls, even though this even outs as the population ages as males die younger. What User:Philc_0780 said could be it, but I'm still not sure. Phgao 03:56, 12 September 2007 (UTC)

Relative size of the sun

If the Earth was the size of a pinhead, how big and how far away would the Sun be? I was thinking about this and realise I have no idea - I mean I know it would be big, but what, as big as a fridge? A house? A country? 195.60.20.81 16:01, 11 September 2007 (UTC)

You can get the actual sizes by reading our encyclopedia articles: the Sun has a diameter of 1.392×10 m and is 1.496×10 m from earth. The Earth has a radius of 6,372.797 km. In your model, the earth is a pinhead (estimate about 1 mm for convenience), so you just need to scale all the measurements to match. Actually, the Sun article even tells you explicitly that its diameter is equivalent to 109 earth diameters, so that's 109 pinheads without having to do any math at all, or 109 mm (which is about 11 cm). DMacks 16:51, 11 September 2007 (UTC)

I found this question interesting. Thanks. So, you are saying that ... if the Earth were the size of a pinhead, then the Sun would be the size of 109 pinheads ... correct? And what about the distance? Measured in pinheads, how far is the distance from the Sun to the Earth? Also, can you give a reference example, such at the question originally posed? That is ... can you please fill in the two blanks with the names of a common and recognizable everyday household object: If the Earth were the size of a pinhead, the Sun would be the size of a __________ ... and the distance of the Earth to the Sun would be the size of a __________. Thank you. (Joseph A. Spadaro 17:03, 11 September 2007 (UTC))

For the distance, the sun is 1.49e11/6.37e6 or 23478 earth diameters away. If the earth was 1 mm, that would be 23478 mm = 23.4 m, or about 25 yards.128.163.170.17 17:26, 11 September 2007 (UTC)

So that's a pinhead and a grapefruit and either end of my standard swimming pool.--Shantavira| 18:34, 11 September 2007 (UTC)

Make that a football, because I just bothered to actually measure a pinhead and it was 2.5 mm wide. It's rather common to misjudge the size of small round objects. DirkvdM 18:51, 11 September 2007 (UTC)

Yeah, depends what kind of pins you use for reference (I hate using "normal" objects for reference size when the object's variation is so relatively large). The pins I usually use have a head that's just the end of the wire pressed down (like the head of a nail), barely wider than the wire itself. Very much smaller than the easier-to-handle (and admitedly better for building a scale-model:) than the oversized plastic heads as in Image:2006_01020005.JPG. DMacks 20:04, 11 September 2007 (UTC)

• 128., I believe you mixed up radius and diameter. If the Earth was 1mm in diameter, the sun would be 11.7 m away. --Sean 23:27, 11 September 2007 (UTC)

• You might also be interested in Solar system model. --Sean 23:19, 11 September 2007 (UTC)

We need to add pinhead to our list of unusual units of measurement.--Shantavira| 09:27, 12 September 2007 (UTC)

Determine the voltage/current for random LEDs

Hi all,

If I were to get a big bag of random LEDs (like those here with big ones, little ones, rectangular ones etc, how could I determine the correct voltage and current to use them with? Can I just go by the color, like in the chart at the bottom here — is that the same for all shapes and sizes? Can I use my multimeter to work it out?

Thanks! -Sam. 17:56, 11 September 2007 (UTC)

Our article on LEDs contains a table of voltages for different colours of LED - all LED's of the same colour take the same voltage range. You should properly connect up the LED with a current limiting resistor - but the amount of current required for a particular LED depends on the nature of how it was manufactured - and how much light it's going to put out - and to know that you need a data sheet. You could hook each one up in turn to a variable resistor and slowly change the voltage until the LED lights with an acceptable brightness (or blows up!). That would let you know how big a resistor to wire up to each type. SteveBaker 19:20, 11 September 2007 (UTC)

And, assuming your series resistor is (or can be) big enough, the voltage you start with doesn't matter so much. Just use 3v or 5v or whatever you've got handy. When you've chosen a resistance that seems to give you the right brightness, you'll have empirically determined both the LED's current draw and voltage drop. —Steve Summit (talk) 00:38, 12 September 2007 (UTC)

Connecting it to e.g. a 20mA current source would also work, if you have one handy. Then you can slowly crank up the current until it's bright enough for your purpose. --antilived 20:12, 11 September 2007 (UTC)

Indeed. But if you don't know what a current source is and how it differs from the more usual constant-voltage power supply (i.e. voltage source), definitely go with Other Steve's variable resistor suggestion instead. —Steve Summit (talk) 00:30, 12 September 2007 (UTC)

FYI: 20 mA is too much for some LEDs; I'd start with 5 mA instead. Also, a very few LEDs contain internal resistors or current-limiting chips; these will give surprising results as you vary the voltage/external resistor, but if you know these variants exist, you'll be able to figure out what's going on if you see one. Finally, while diode voltage and color are intimately related for monochromatic LEDs ('cause it produces photons with x electron volts of energy), the operating voltage for "White" LEDs varies depending on which technology they use to produce the "white" light; today, most are actually blue LEDs with phosphors/scintillators that convert some of the blue to yellow.

Atlant 14:32, 12 September 2007 (UTC)

What's this called?

(I was going to say "what's the matter with my mind?", but it seems too melodramatic). I've been enjoying contributing here over the past several days, and it really strikes me how my mind is what my wife calls a "steel trap" for abstract things like the scientific names of organisms and random trivia, but I can't for the life of me remember people's names without hearing them or reading them repeatedly. This applies equally to people I meet, actors, etc. (but not, oddly enough, to politicians). I know it's a form of selective memory, but it's really embarrassing sometimes, and I know it's not unique to me. Is there a name for this problem? --SB_Johnny | 19:51, 11 September 2007 (UTC)

Autism is often characterized by highly developed mental faculties with very poor social skills (such as proper behavior around people, and inability to use names, etc). It doesn't sound like you're there, but my understanding of psychology is that there's a very broad spectrum, rather than precise categories. Nimur 01:25, 12 September 2007 (UTC)

Ouch! I can relate only too well to you, Johnny, but I'd shrink from any thought that I was even minimally autistic. (People who know me may well disagree.) I know exactly what you're experiencing. I have a mind full of a bazillion bits of (mostly worthless) information, but putting names to faces - and even recognising faces I've met before - is becoming harder and harder. It's very embarrassing, and I'm aware I've unconsciously developed ways of avoiding revealing that I don't remember the name of the person I'm with. I always assumed it's a part of the ageing process, and I've more than once wondered if I'm meandering slowly but inexorably into Alzheimer's territory. -- JackofOz 01:37, 12 September 2007 (UTC)

I can also relate very well. My wife has an irritatingly reliable memory when it comes to names, faces, what people have given or gotten what gifts and what people wore at events even in the distant past. On the other hand, I have an extremely hard time with it. I also wondered what the matter was until it struck me: I didn't really care all that much. I can recite baseball stats and comic book lore and an insane amount of science type stuff. Why? I find it interesting. To be blunt, I just don't care for most people all that much; I don't *hate* people, I just find most folks tedious or irritating. Uh, present company excepted, of course. I think my issue is that I unconsciously decide not to expend the energy to memorize a name/face combo because I unconsciously don't care to. By that same token, I can remember a great many details about the friends I do have, probably because I actually pay attention when they're talking.... Matt Deres 02:13, 12 September 2007 (UTC)

"Me too." I think part of it is that I remember data better if they're part of a pattern, and the names/faces of random people aren't. Every time I start a new job, someone leads me around and shows me all the people there, and maybe they remember me but for me it's a dead loss: they don't individually attach to anything yet. —Tamfang 07:21, 12 September 2007 (UTC)

The inability to recognise faces is called Prosopagnosia. Graeme Bartlett 04:34, 12 September 2007 (UTC)

And the inability to remember names is Dysnomia. Although I'm not sure if this covers the inability to remember names (which I can relate to) when one can still remember most other things quite normally. Someguy1221 04:38, 12 September 2007 (UTC)

And a realted thing is tip-of-the-tongue (TOT) phenomenon, when you cannot recall on time when you need to say it, but it is in the memory hidden away. Graeme Bartlett 04:43, 12 September 2007 (UTC)

Tamfang's description nails it fairly well... maybe it's just that I am using mnemonic devices for other things that I'm not fully aware of. I think Dysnomia might be the word I was looking for, thanks Someguy1221!

From what I understand of it, Autism would be a problem in relating to others, not naming them (a subject/subject relationship, rather than a subject/subject-as-object relation). That's sort of the problem though... people often think it's rude not to lremember their name, when it's really just a memory problem :). Probably not Alzheimer's though... I've had this problem as long as I can remember :). --SB_Johnny | 08:47, 12 September 2007 (UTC)

Autism isn't it - people with extreme autism wouldn't be generally likely to ask questions at the Misplaced Pages reference desk - and those that could would be very aware of their problems and the cause. Try Aspergers syndrome - similar kind of thing but very commonly undiagnosed (I have Aspergers and I didn't find out until I was 45 years old!). Dysomnia would prevent you from remembering other facts - not just names - and we know you can remember lots of other stuff very well ("a steel trap"!) - so that's not it. But let's not stray into medical diagnoses because that would be 'A Very Bad Thing'.

What is much more likely to be the case (and this is a problem I have) is that when you first meet someone and they tell you their name, it simply doesn't matter enough to you to make you want to remember it...especially when you are about to launch into a complicated discussion about something. There is something bigger on your mind at the time - and the name gets crowded out. You have to make a conscious effort to listen for the name, ask for it again if you aren't sure you got it right - repeat it back to the person - and (crucially) keep it in your head long enough for it to lock into long-term memory. At my last company, everyone had to wear security badges with their names on them - so partway through a conversation with a stranger, I could check their tag and be sure I'd gotten their name right - that helped a lot. Where I work now we have a database of employees with names and photos - so in the worst case I can look up their picture and get a name that way. SteveBaker 14:41, 12 September 2007 (UTC)

Rear Facing Missiles

Why don't fighters (or any other aircraft for that matter) mount rear facing missiles to use on pursuing aircraft? Since modern missiles are all-aspect they could easily track a pursuing aircraft and could be used to destroy them or at least force them to break off pursuit to evade the missile. Exxolon 22:13, 11 September 2007 (UTC)

There's a basic two-fold answer to this:

1. Facing only matters at close range. At intermediate or longer ranges, it's trivial to turn and face another aircraft.
2. Missiles are largely ineffective at close range, as demonstrated by the F-4 Phantom (among others) in Vietnam.

— Lomn 23:46, 11 September 2007 (UTC)

This is a complete guess, but maybe because planes fly forwards through the air, it might be aerodynamically easier for the missile initially to face forwards. --70.174.143.76 01:44, 12 September 2007 (UTC)

Also, a plane's targetting radar usually faces forwards, so in the absence of airborne (AWACS) or ground based radar, you would need to orient the plane towards the target to get a lock. —Preceding unsigned comment added by 138.29.51.251 (talk) 02:47, 12 September 2007 (UTC)

The trouble is that a rocket (unlike a bullet) leaves its launcher at zero relative speed. When you launch one backward, it's at the same airspeed as you but tailfirst, and its fins tend to flip it around. —Tamfang 07:27, 12 September 2007 (UTC)

Perhaps our OP is thinking of Firefox (movie) which featured rear-firing thought-controlled missiles on the (then fictional) MiG 31. The real MiG-31 is called 'Foxhound' and has nothing particularly fancy about it!

I used to design simulators for F16's. F18's, F117's and F22's, so I can claim some expertise here. I don't buy most of the preceeding arguments - I think Lomn has it about right. If they wanted rear-facing rockets, they could make them. They don't exist because they simply aren't needed. A hypothetical rear-facing rocket would come with rearward-pointing targetting equipment. All of these missiles have their own radar or IR camera guidance systems anyway - which the host aircraft ties into before launch in order to lock on to the target - so that's absolutely no big deal. The missile could be equipped with fins that only popped out when its airspeed was large enough...or it could have fins at the front of the missile to keep it stabilised until it's at zero airspeed which then retract when the thing has forward airspeed. However, these missiles accellerate at an ungodly number of g's and often have vectored thrust to help steer them. I think they could remain stable long enough without all of that complexity.

The fact is that (Hollywood notwithstanding) here in the 21st century you don't chase the other guy's plane around the sky in ever decreasing circles like a world-war one biplane until you get on his tail about 100 feet away then carefully line him up in your crosshairs and shoot the missile - that's just dumb! This happens in "Top Gun (movie)" and nowhere else! The plan is to sit around 10 to 20 miles away, line him up in your radar and shoot him down from a very great distance! Most aircraft can simultaneously lock on, launch and fire at a handful of enemy planes at once! Some of the more modern varients have sights built into the pilots helmet that project crosshairs onto the inside of the cockpit canopy to show where the targets are as he turns his head to look at them. Even if you are facing the wrong way - if you aren't right up close then you can shoot the missile forwards, have it go around in a nice gentle curve and whack the guy who is behind you. The pilot pretty much chooses who to hit and the aircraft, sensors and missiles figure out how to do it. Missiles go much faster than a plane and can turn way more sharply - why chase the enemy with an aircraft when you can keep your expensive plane and vulnerable pilot a nice long way away - and chase the bad guy with a homing missile? This is really not a problem with modern technology. For the most modern aircraft, air-to-air combat is pretty much an irrelevence (except maybe for taking down helicopters) - these days the big concern is ground attack - and rear-mounted missiles don't offer any kind of theoretical benefit in those cases. SteveBaker 14:23, 12 September 2007 (UTC)

So if I understand correctly it's really a case of this tech isn't deployed as it's not needed. Most engagements are beyond visual range and with off-boresight launching you can fire missiles behind you anyway at any appreciable range. Actual dogfighting is so rare that such as system would very rarely be of any use.

Of course this does beg the question of why fighter pilots have to meet such exacting requirements if all they essentially do is sit up there in the sky and program a computer to blow the enemy planes out of the sky.

And it's very indicative of the way modern warfare is conducted in that the individual skill of a pilot may not count for anything at all if there is a mismatch in the level of technology in use. He who has the best weapons and platform wins regardless.

Exxolon 19:32, 12 September 2007 (UTC)

There are far more applicants to be pilots than there are planes for them to fly - therefore the airforces of the world can afford to take the best applicants whether they need the best or not. To be fair, there are some tasks that require good eyesight, excellent reactions, spatial perception, etc. Landing on a carrier deck comes immediately to mind. Technology certainly plays a major role - not only in the plane but also in the pilot training. Until just recently I designed the simulators that these guys learn their jobs on - one shouldn't underestimate the value of training - a fighter is a REALLY complicated machine and the pilot has an insane amount to learn in order to operate it correctly. But the era of the manned fighter is coming to an end. We've seen the 'spotter plane' role be taken over by the unmanned 'Predator' UAV - it can stay in the air for 36 hours and costs a tiny fraction of the cost of a manned aircraft. Now the Predator carries air-to-ground missiles and the light ground attack role is gradually switching over to them. It's only a matter of a few years until we start to see unmanned aircraft doing all of the dangerous 'up front' stuff in fighter and ground-attack roles. When you take the pilot out of the plane, it gets smaller, cheaper and lighter - also stealthier and more expendable. Many modern fighters can pull more G's than the pilot can stand without blacking out - and getting the pilot out of the machine can only help. I think we have maybe a decade to go before we have no more fighter pilots in the USAF. SteveBaker 03:12, 13 September 2007 (UTC)

Water to burn

A fanous medical researcher discovered that if he exposed seawater to radio frequency energy, hydrogen was liberated and would burn. The article talks about the ocean as a fuel source. So: how much energy do you expect it takes to break the hydrogen bonds, compared to the energy derived from burning the hydrogen? Edison 23:29, 11 September 2007 (UTC)

That's kind of my question. If you liberate the water using a combination of radio waves and heat, and then burn that to get water again, you're no better off energy wise. It would be analogous to splitting water completely using electricity and then burning the hydrogen and oxygen; there is no net energy gain. I have yet to see a scientific writeup of this, and am mostly curious why it has to be salt water (and does the kind of salt matter? ie NaCl vs. KCl vs. CaCl₂). Of course these will be tested since this is a relatively recent discovery. —Preceding unsigned comment added by Bennybp (talk • contribs) 00:07, 12 September 2007 (UTC)

Misplaced Pages already has an article on the inventor, John Kanzius. Abecedare 00:49, 12 September 2007 (UTC)

Are you sure it has to be sea water? The primary reason AFAIK why most attempts to liberate hydrogen from water use sea water is because there is a lot, lot, lot more sea water then there is fresh water. Many places have problems with the lack of fresh water and some people even believe there may be major wars of water in the future. However obtaining sea water is not a problem and we're not likely to run out of it any time soon. BTW, although it's true you're never going to come close to breaking even let alone having a net energy gain from liberating hydrogen, the idea is that you use some sort of environmentally friendly power source e.g. solar to generate the power used for splitting the water and you then have an environmentally friendly fuel you can use for things like cars or more generally as a energy store. Whether or not this will work out or stuff like electric cars (with batteries) and biofuels is a better idea remains an open question Nil Einne 20:22, 12 September 2007 (UTC)

I've got another idea for a great energy source: compressed springs. Get a bunch of these, in a convenient size and configuration, and every time you need some mechanical energy, release one. If you need electrical energy instead, arrange things so that the releasing spring drives a generator. When your springs are all unsprung, just squeeze them back again and start over. Presto! Infinite energy! —Steve Summit (talk) 00:49, 12 September 2007 (UTC)

How would you squeeze them back again? Either you would have a heck lot of manual labor or more electrical energy to run the very act of compressing the spring back. Besides, you would have to have a lot of spring to generate a sustainable amount of energy. bibliomaniac15 15 years of trouble and general madness 00:54, 12 September 2007 (UTC)

Exactly. You've understood the problem with the guy who's claiming to get energy out of burning seawater. --Reuben 01:08, 12 September 2007 (UTC)

<sigh> This keeps coming up - it's bogus. You take water - you apply a certain amount of energy to break the oxygen/hydrogen bond. Then you burn the hydrogen into oxygen - remaking the bonds and liberating some energy and some water. The energy to break the bond is the same as you get back when you re-form it - but your machine cannot possibly be 100% efficient - so you lose. The first law of thermodynamics applies no matter how devious you are with using salt water and radio waves or any other wierd gadgetry (typically magnets are also involved) - and it says you can't gain energy out of thin air like this. Think about this. Use electricity to make radio waves, use the radio waves to split the bonds of some water and liberate oxygen and hydrogen. Then we can burn the hydrogen in a fuel cell or something to make electricity. Let's use the electricity to split up more water - and put the water back into the tank. What we have here is a perpetual motion machine...unless some energy is lost in this process. We know from the laws of thermodynamics that perpetual motion machines are impossible. So it's a given that it will DEFINITELY cost you more energy to split the water into hydrogen and oxygen than you'll be able to recover when you burn the hydrogen. Definitely, no doubt, no debate, for sure. So why mess around with the water and the hydrogen - let's just take the energy we'd have used to split it and use it to drive whatever it was you were going to drive with the hydrogen. The ONLY reason to do this inherently wasteful thing is if it's more convenient to store the hydrogen than it is to store the electricity. The problem is that too many people are enamored with the idea that somehow, if they could just come up with some tiny efficiency improvement (typically involving magnets and radio waves and such) then they could win on the deal. In their very next breath they will say it could be used to power a car - then come the accusations of 'big oil' and car manufacturers supressing the technology, threatening their lives, etc. Typically they'll patent their bogus contraption and then claim (to gullible investors) that "it must work because the US patent office investigated it and they say it works"...<sigh> SteveBaker 02:49, 12 September 2007 (UTC)

To be fair, according to our article, John Kanzius "admits that his machine requires more energy than it releases". —Steve Summit (talk) 03:08, 12 September 2007 (UTC)

He seems to have admitted at one point that it used more energy than it released at that point, but according to the blogosphere, he's now claiming to be over unity. Unfortunately, the only sources on this are Kanzius himself and Roy, filtered through rather naive local reporters and blogs, so the signal to noise ratio here is basically zero. --Reuben 04:07, 12 September 2007 (UTC)

There's a lot of energy potential in the ocean. We use it all the time through the magical properties of water vapor. The sun picks up part of the ocean, puts in a cloud, moves to a mountain, drops it and lets it turn a generator and then put it back in the ocean. You could then use that electricity to separate hydrogen from oxygen but that's not very efficient since it takes a lot of energy to separate those bonds. It would be better to use the electricity to separate hydrogen from fuel oil. --DHeyward 03:42, 12 September 2007 (UTC)

The energy there comes from the sun, not the ocean. You're describing hydropower, which doesn't take energy from the ocean at all. -Reuben 04:07, 12 September 2007 (UTC)

Hello??!? Sense of humor <on> --DHeyward 07:20, 12 September 2007 (UTC)

Sorry, my fault... it's (temporarily) out of commission after seeing some of the news stories on this. --Reuben 07:42, 12 September 2007 (UTC)

(edit conflict)

It's vital to distinguish between actual energy production and mere energy storage.

• Hydroelectric energy is, as you say, driven almost directly by the sun, which is responsible for the elevation of water vapor into the atmosphere. (It has little to do, as Reuben noted, with any "energy potential in the ocean".)
• When we burn fossil fuels, we are in effect cashing in on solar energy captured millions of years ago by plants.
• Electricity generated by photovoltaic cells and solar-powered heat collectors is obviously directly powered by the sun.
• Energy derived from windmills is extracted from weather systems which are ultimately powered by the sun.
• Geothermal energy is extracted from the latent heat of the earth's core, left over from the primordial fireball (of sorts) out of which our solar system was formed. By extracting that energy we're hastening the cooling of the planet to a degree, but of course it was cooling down anyway.
• Nuclear energy is derived from radioactive elements left over from that same primordial cauldron.
• Any energy we manage to extract from the tides is in a roundabout way stealing angular momentum from the moon. (But, again, that was happening anyway; we're just riding on its coattails.)
• If we ever succeed in sustained, controlled fusion, that will be essentially "free" energy, "burning" hydrogen to helium and costing us nothing other than, in a small way, hastening the iron death of the universe. (But so far our attempts at fusion have all required quite a bit more energy input than we've gotten out, and the equipment required is decidedly not free.)

But just about everything else -- batteries, hydrogen electrolyzed from water, chemical energy of all kinds, springs, water pumped uphill, etc. -- is just storage, is just conversion of existing energy from one form to another. The conversion and storage may be very, very useful, but it doesn't create any new energy. (In fact, it always loses a certain amount of energy, because no storage process is 100% efficient.) —Steve Summit (talk) 04:26, 12 September 2007 (UTC)

It is unfortunate in this day and age that all the world is controlled by powerful corporations, many of whom are intent on preventing the rise of any cheap new technology that might weaken their stranglehold on global wealth. Can you imagine what Kanzius' inventions would do to the electrical and pharmaceutical companies? If he provided proof that his inventions work, or details of their manufacture, they would be stolen out from under him, and the man himself would be brutally silenced. We should applaud him for his efforts, and provide him the support he needs to make cheap and effective sources of power, as well as the cure to cancer, available to the world populace. Someguy1221 04:21, 12 September 2007 (UTC)

Either your tongue's in your cheek, there, or you really haven't gotten this discussion at all. TANSTAAFL. —Steve Summit (talk) 04:31, 12 September 2007 (UTC)

All I've seen so far are you guys reiterating the version of science that's been fed to you by the government and multinational corporations. Someguy1221 04:39, 12 September 2007 (UTC)

Well, actually, no.

I don't expect to convince you, but the key difference between science and other, faith-based systems of thought is that you do not have to take science on faith. Many people do, of course (and this is rather sad), but when I say that perpetual motion is impossible and that you can't create free energy from nothing, I am most certainly not just regurgitating something I've read (much less something I've been fed). I understand this stuff, it makes sense to me, it all hangs together as part of a huge interwoven tapestry of scientific ideas, all supporting and reinforcing each other, all confirmed directly by empirical evidence or by ironclad logical chains firmly rooted in empirical evidence.

Scientific truth is not just another belief system which you're free to choose or not choose based on fashion or sociopolitical whims or what feels good or who shouts the loudest. If you understand science, really understand it (and anyone can), the chances that there's something so wrong with it that a heretical result such as perpetual motion might actually be possible are precisely 0.000000000%. —Steve Summit (talk) 04:53, 12 September 2007 (UTC)

Ummm SomeGuy, do you seriously mean to say you believe that conservation of energy is a myth dreamed up by the government and multinational corporations? Really now? I hope this is just another case of my tongue-in-cheek detector being out of alignment, and that you're not serious. --Reuben 07:16, 12 September 2007 (UTC)

Oh, forgive me; I forgot to bracket my response with <devil's advocate></devil's advocate>... Someguy1221 08:36, 12 September 2007 (UTC)

That's good because I was just about to mentally bracket it with <complete idiot></complete idiot>! SteveBaker 13:50, 12 September 2007 (UTC)

There are really two questions here:

1. Is electrolysis involved?

2. Is more energy generated than put in?

As for #1, I'm skeptical, but it's conceivable. He's reportedly using ~14 MHz (quoted here from one of the videos). It only takes a few V across salt water to get H₂ and O₂, so the voltage is easily sufficient. That's also true in a microwave oven at 2.45 GHz, yet your microwave oven doesn't generate hydrogen gas when you use it to boil water. It would be spectacularly dangerous if it did! 60 Hz has been reported to work (although perhaps not as efficiently as DC). The question then is whether or not 14 MHz is a low enough frequency to have any significant effectiveness in electrolysis. It's a question of the time constants for mass transport. It seems unlikely, but not impossible. Alternative hypotheses: something akin to a microwave plasmoid?

As for #2, not on your life. If he's right, he's using RF energy to break apart H and O in water, and then burning the hydrogen to make water. If it were able to generate net energy, as Kanzius does appear to be claiming, it would be a perpetual motion machine of the first kind. In this house we obey the laws of thermodynamics! --Reuben 08:06, 12 September 2007 (UTC)

In a very important sense - it doesn't matter a damn how his machine works. It can't be an 'over unity' device because of the first law of thermodynamics - and it can't be "extracting energy from water" because the net result of burning the hydrogen is water so any (hypothetical) energy he extracted would have to be put back in again. So at best it's an energy conversion/storage device. Looking at it in that regard (which is the most charitable thing I can manage), it's only really useful if there were an abundant source of these radio waves out there that was going to waste - and there isn't. Failing that, you'd have to make the radio waves using electricity. On a very large scale, that could be 98% efficient - but we don't know how much of the radio energy goes into splitting up the water and how much is wasted in other ways. If you just want to take electricity and use it to split water into hydrogen and oxygen then you'd use electrolysis. Electrolysis (done right) is about 70% efficient - and theoretically, with the right catalysts and such, it could be made 94% efficient. So I suppose it's just possible that this guy has come up with a fractionally more efficient way to convert electricity+water into oxygen+hydrogen. It's not breathtakingly, amazingly great - and it's only going to work on very large scales because small-scale radio transmitters are much less efficient than electrolysis - and we're assuming that all of the radio energy does indeed go into splitting water molecules and none into heating things up or other wasteful side-effects. Look guys - we've seen these ridiculous claims dozens and dozens of times before - and every single time they are bogus. That should come as no surprise because the first law of thermodynamics is one of the most solidly proven laws we have - it's been around a very long time and it has stood the test of time. It's not likely to be broken - and if it is, it won't be in 'normal' realms of matter and energy...it'll be something in a black hole or at a quantum level or something wierd like that. It won't be in some rinky-dink experiment with radio waves and seawater taking place in someones garage. SteveBaker 13:50, 12 September 2007 (UTC)

Steve, of course, the laws of thermodynamics are not broken, see the "not on your life" in my answer to #2 above. But the question remains, what is the flame? It's actually quite surprising if RF can dissociate water. The frequency appears to be far too high for electrolysis (you really want DC), and far too low for photolysis (you need UV). If it were hot enough for thermolysis, the water should be boiling. So if there really is a significant amount of hydrogen coming out, that is indeed unexpected, interesting, and worth understanding. My guess is, this is not a hydrogen flame at all, perhaps an RF plasma of ions from the match. --Reuben 18:19, 12 September 2007 (UTC)

I suspect that the flame is indeed hydrogen burning in oxygen (possibly with traces of sodium from the salt making for a pretty colour). RF (at reasonable power levels) can't dissociate water - but how do we know that our enterprising inventor didn't put some kind of induction coil/antenna into the tank to convert the RF into electricity again? Given the exceedingly dubious credentials of the "scientist" whom he demonstrated this to, it's possible that the whole thing is a total fabrication. (See below - the scientist turns out to be an 84 year old guy who believes in healing people with magnets...(why is it always magnets?!)). The motive of these crackpots is often to pursuade gullible investors to give them money - many of them end up in front of a judge as a result of this dubious practice. Nothing short of peer reviewed papers in long established journals and duplication of the experiment by some reputable institution should be considered as 'proof' that this event happened at all...and even then, remember the cold fusion fiasco. SteveBaker 02:59, 13 September 2007 (UTC)

Two problems: 1) the induction coil would still be going at the same frequency! Same issue as before! 2) I think we should give the local news reporter enough credit to suppose that he would have noticed that. --Reuben 03:41, 13 September 2007 (UTC)

In my experience, claims of 'over unity', 'perpetual motion', or other technological miracles usually stem from one of (or a combination of) the following factors.

• Sheer fraud.
• Delusion or error of various sorts:

• Failure to accurately measure energy in or out of a system.
• Failure to account for one or more sources of energy into the system. (Non-obvious power sources, energy stored prior to the start of measurement, etc.)
• Failure to include all important physics/chemistry in the model chosen; failure to justify (or be aware of) any simplifying assumptions that may fail under unusual conditions. (See EmDrive.)
• Failure to do the math correctly.

• Genuinely new physics or chemistry that doesn't violate conservation of energy but requires an extension of our understanding of conservation principles.

The last case is very rare, and should only be considered after the other much more likely explanations have been ruled out. If we gave a scientist in 1875 a little lump of plutonium, he'd be faced with a 'perpetual motion' type of problem—not knowing about radioactivity, he'd be faced with a material that constantly generated heat without combustion or chemical reaction.

Much more often today, a self-described 'scientist' will announce his 'discovery' of a novel physical principle fabricated on the basis of sloppy experiments and wishful thinking. (An example from not-too-long-ago on the Ref Desk would be Ruggero Santilli, his magnecule theory, and his ridiculous paper, "A new gaseous and combustible form of water".) TenOfAllTrades(talk) 14:20, 12 September 2007 (UTC)

As Carl Sagan said, "extraordinary claims require extraordinary evidence", and fooling a local news reporter about science is not particularly extraordinary. --Sean 15:34, 12 September 2007 (UTC)

I periodically put in the effort to try to fix up Water fuel cell and Water fuelled car - it's pretty futile though because the nut-jobs on those pages mostly outnumber the (relatively) sane scientists. If you want to see some empassioned arguments in favor of all of this junk science, check out the talk pages of those two articles. It's truly depressing reading. SteveBaker 17:17, 12 September 2007 (UTC)

Maybe I'm missing something, but I think there might be something to this. No, I'm not suggesting that he's successfully violated the first law of thermodynamics- I understand enough science to know that this law is about as solid as anything can be. If the radio energy required to do this is less than the power you get right then, this may be a useful technology for making engines. Yes, the water is just storing energy, and we're not coming out ahead in the grand scheme of things, but we already have the salt water. We can consider it effectively "free" for our purposes. And yes, I realize that eventually the burned-up stuff will need to be turned back into water, and yes, this takes energy, but the atmosphere will do this by itself if we just leave it alone, right? In other words, the work that needs done on the other side of the cycle will be done using (I presume) solar power, which is effectively "free" to us. The earth already has a water cycle which operates using energy we can consider "free", since we don't have to go out of our way to make it happen. Friday (talk) 17:36, 12 September 2007 (UTC)

It's not that it needs to be turned back into water, it's that the very act of burning the ("activated"?) water creates water. The reaction is hydrogen + oxygen = water + heat. This heat would be less, or at the very most equal to, the energy required to loosen the bonds. So you are taking water, loosening the bonds, burning it, and getting water back again. If you just loosen the bonds (and let the atmosphere do the rest), you don't get any work out of it. I personally find the discovery cool from a chemistry/physics standpoint, but not necessarily practical for engines, unless it was more efficient that an electric motor or something. --Bennybp 17:50, 12 September 2007 (UTC)

The energy is not there in the water to start with. Water is the low-energy state. You're putting energy in to get H2 and O2, which have chemical potential energy, i.e. the energy you put in has been stored in their chemical state. Then you burn the H2 to get H2O, going back to the low-energy state. At most, the burning gets out as much energy as you put in. It's exactly the same as pushing a ball up a hill, and then recovering energy as it rolls back down. --Reuben 18:19, 12 September 2007 (UTC)

I was reading the original article that our OP quoted. In there it says "Rustum Roy, a Penn State University chemist, has held demonstrations at his State College lab to confirm his own observations." - which certainly makes you think: "Wow! A serious scientist at an established university says that it works! But then it says "The scientists want to find out whether the energy output...would be enough to power a car or other heavy machinery."...which is an immediate red-flag. If you had invented a totally revolutionary technology that produced energy in an utterly new way - why on earth would you start even thinking about putting it into a car before researching how and why it works and collecting your nobel prize? It's a classic mark of a crackpot to move directly from experiment to functional technology without looking carefully at the intervening science. So I looked up this Rustum Roy chap. The first Google hit said: "Rustum Roy cannot be described by any professional label."...uh...huh...OK, that's not a good sign. "He has interwoven throughout his 60 year career..." (yeah - he's 84 years old) "...both world-class science and active participation in reforming theology and the practice of religion. He is at once a distinguished research scientist and a social activist, a societal reformer and a champion of whole person healing (CAM)."...hmmm. So what about this 'whole person healing' thing? Well, it turns out this is another of those "something magical happens with magnets" thing: "Ayurvedic Healing and the Science of Electromagnetic Healing" according to the website relating to the conferences he presented at. So the so-called scientist who is backing up these crazy claims is actually someone who was indeed once a respected scientist - but in his 80's has turned to religion and bizarroid healing-with-magnets stuff. This is not someone whose opinions I'd trust. SteveBaker 17:59, 12 September 2007 (UTC)

September 12

White bread - is it bad for the gulls?

I've seen this subject raised in various places online by those with an interest in feeding the larids. Is white bread *really* an unhealthy food to give to the gulls? The 'common wisdom' seems to be that one must only feed them wholemeal bread, as white bread is nothing but 'empty bulk' and 'bad for the babies'. Anyone actually know the facts? I very rarely feed them the above for this very reason - but I'm beginning to wonder if there's actually anything to it. --Kurt Shaped Box 00:50, 12 September 2007 (UTC)

Kurt, if anyone else had asked this question, we would have been waiting for you to answer it! DuncanHill 00:53, 12 September 2007 (UTC)

In Australia, white bread is bad for kangaroos and wallabies as it causes their teeth to rot. Your gulls don't have teeth do they? I expect that they may suffer a vitamin and protein defficiency if you fed them too much white bread. White bread with sugar on it has been called white death. Graeme Bartlett 01:12, 12 September 2007 (UTC)

Hmmm. I wonder if sugar causes 'beak rot' in birds? Never considered that before. I know that I used to envy my pet birds for having no teeth when I was a kid - my mouth looked like (and still does look like) Shane MacGowan's due to a genetic thing and causes me much pain and hassle. :) I've noticed that the gulls will only really eat bread if there is nothing else to be had. Bread is considered the standard 'bird food' but I've noticed that they prefer meat, boiled eggs and cheese. Guess that you can't teach an old carnivore new tricks. :) --Kurt Shaped Box 01:30, 12 September 2007 (UTC)

I think it's exaggeration to call white bread "empty bulk." I'm comparing a loaf of white vs. wheat right now, and I see exactly 186 calories per four ounce serving in both nutritional fact labels. Surely, the methodology may be called into question; whether the numbers are exact; how much actual caloric content can be absorbed by a human dietary tract (let alone a bird!) Nonetheless, I think that's a largely false claim that the wheat bread is more nutritious. I see equivalent carbohydrate, sodium, and even protein, in both of these loaf labels. Nimur 01:34, 12 September 2007 (UTC)

While I'm not disputing that there may be too much hysteria about the 'badness' of white bread, bear in mind that one of the disadvantages of white breads or more generally refined cereals is that they tend to have higher Glycemic index. Although in the case of breads according to the GI articles some brown breads can be just as bad due to the addition of enzymes. White breads or refined cereals also tend to have less Dietary fiber and lower vitamin and mineral levels. (Not talking about sodium or potassium here which most people probably don't have trouble getting) The low vitamin and mineral levels are the predominant reason AFAIK why things tend to be called 'empty bulk'. Nil Einne 20:09, 12 September 2007 (UTC)

And deciding what you should do depends on what you are trying to achieve. Do you want segulls to pester you for food, in which case feed them (anything). But if no one ever supplied them with food, they would leave humans alone. Are you feeding a pet that you want to keep healthy, or just some random birds that will appreaciate anything better fresher than the normal tip food that they consume? Graeme Bartlett 01:47, 12 September 2007 (UTC)

This is probably irrelevant, but I've heard that feeding Paracetamol or Panadol to gulls causes them to die, but this may be a myth. But I think that feeding animals food which is not their normal food causes them to be too reliant on this food, and thus lose the ability, or want to look for their own food. A recent study which I remember ready did a survey on innercity seagulls and seagulls near the coast with no humans around. The inner city ones had a higher death rate and were fatter; with less muscle. The coastal ones were leaner and more muscular and capable of living longer. So.. that's why we are often told not to feed wild animals. (could be a part reason). Phgao 04:02, 12 September 2007 (UTC)

When i worked on a gull colony 23 miles away from San Francisco the gulls there would feed their chicks any amount of human rubbish from the city. Gulls are natural oportunists, but I doubt Giants game hotdogs are the best food for growing chicks! Sabine's Sunbird talk 04:44, 12 September 2007 (UTC)

Eating one panadol pill for a seagull, is probably like a human eating 50 or 60 pills. It's bound to have a bad effect! My science teahcer used to feed sodium metal to gulls, that was unhealthy. I think they will eat anything white. But they won't touch fruit and vegetables! Graeme Bartlett 04:47, 12 September 2007 (UTC)

Why did he (your teacher) do that? Sounds like an arsehole to me. Gulls will eat boiled potatoes and sliced apple, FYI. --Kurt Shaped Box 19:49, 12 September 2007 (UTC)

Hi Graeme. I basically like to feed my local flock of gulls a decent meal three or four times a week. There are about 25 birds, mostly lesser black-backed gulls that hang out in my street and build their nests on the rooftops in the surrounding area. I first got 'into gulls' in a big way (though I always thought they were interesting) after I hand-raised an orphaned gull chick (she turned out to be a great black backed gull - an absolute tank of a bird) and started feeding her every day after she fledged. The other gulls started coming for food at the same time, I started to recognise individuals and it all went on from there, really. Quite a few of my neighbours feed them too. --Kurt Shaped Box 19:59, 12 September 2007 (UTC)

If we can accept that refined white flour is bad for people, certainly it would be bad for all mammals. Metabolism and malnutrition are the same whether you're a chipmunk or a beluga. Vranak 17:30, 12 September 2007 (UTC)

But a seagull isn't a mammal. SteveBaker 18:42, 12 September 2007 (UTC)

I would assume that feeding them anything other than their natural diet of fish or whatever would be bad for them. It doesn't matter what's in the bread so much as it's filling the bird's stomach with something that isn't full of the things that fish are full of. SteveBaker 18:45, 12 September 2007 (UTC)

I don't actually give the gulls that much bread of any kind myself - just the odd few slices here and there to save it going to waste. I generally give them cooked beef/chicken/pork/sheep (my local butcher does me a deal on offcuts and offal - it all goes in a big pot and gets cooked up), boiled potato and boiled eggs. They seem to be doing well on it - loads of large, strong-looking GBB/LBB fledglings with good plumage this year. --Kurt Shaped Box 19:49, 12 September 2007 (UTC)

a wild and crazy question

I know this is a wild and crazy question and one that will require a computer but here goes. How much of the central valley would fill with water and how long would it take to fill if you replaced the Golden Gate Bridge with the tallest possible dam? Clem 05:39, 12 September 2007 (UTC)

Do you mean a dam joining the highest point in San Francisco with an equal height in Marin, or what? (Hm, how high is the saddle point of the San Bruno gap?) —Tamfang 07:10, 12 September 2007 (UTC)

...with and without all coastal land mass gaps filled in to the same height as the dam. Clem 07:49, 12 September 2007 (UTC)

I'm not familiar with the water source. Is it the sacramento river? The would keep rising up through the source whihc would probably be a larer volume than you are contemplating. --DHeyward 07:24, 12 September 2007 (UTC)

The Central Valley is immensely big. You'd need to estimate its volume though to start with a question like this. My quick Google Earth measurements make it feel like it can be approximated as an prolate spheroid with dimensions 400 mi * 64 mi * 1000 ft or so. You do the math. --72.83.170.138 12:19, 12 September 2007 (UTC)

Current weather conditions give a non-tidal flow rate of about 1000 cubic feet per second (at the Folsom Dam at least - it's the only figure I could find, and I'm assuming no rain is going to fall, which would speed things up, nor water evaporating, which would slow things down (hopefully cancelling each other out!)). Using 72.83...'s estimate slightly tweaked (taking half of a 400 mi * 64 mi * 2000 ft ellipsoid instead), I get a volume of 3 × 10 cubic feet (20000 cubic miles). This would take 95,000 years to fill if dammed.

The Golden Gate Bridge however is only 27 metres (90 feet) high. At this level, I can assume the valley is an elliptical prism 400 mi * 64 mi * 90 ft, which would take only (!) 6,400 years to fill before water begins to lap over the edges. I don't know about what would happen without all the other land being filled in - I'd imagine that it would fairly quickly find another route to the sea over the San Francisco peninsula. Laïka 15:11, 12 September 2007 (UTC)

And when you're talking about such geologic size scales, you can't consider things like ground to be water-tight! See groundwater for an introduction. Just because you "seal off" the above-ground flow pathways does not mean the water will stay inside the basin! Incidentally, we have an entire article on groundwater modeling, including links to software packages such as FEFLOW and Visual MODFLOW. These look to be commercial software simulators. Nimur 15:42, 12 September 2007 (UTC)

I hope you're not planning to build a dam there. I happen to live in the central valley and would be very upset. — Daniel 03:04, 13 September 2007 (UTC)

Only if my mom increases my allowance, like she promised, and stops making me buy my own lunch at school. Clem 04:35, 13 September 2007 (UTC)

Embarrassingly simple work question

Heyo there. I have a rather simple (and therefore embarrassing) question regarding mechanical work. According to the article work is defined as the scalar product of displacement and force. I had some difficulty understanding that article as it also mentions distance, but my textbooks support the idea of force x displacement. If I were to pick up an object such as a pen and raise it by a distance of x metres vertically and then drop it to the floor, would I be doing any work on the pen? I would argue that since displacement is 0 then work must be 0, but I could also see it as being the sum of the work required to raise the object and the work done while it drops. Which of these interpretations is correct? Many thanks Vvitor 07:55, 12 September 2007 (UTC)

While raising the pen, you are doing work on the pen. Simultaneously, gravity is doing negative work on the pen. For the time period in which the pen is moving up with constant velocity, the force of gravity equals your force raising the pen, and so in this period of time no net work is done on the pen. And so during this time, while the pen is gaining gravitational potential energy thanks to your own work, it gains no kinetic energy. Remember, the net mechanical work done on an object over a period of time equals its change in kinetic energy. When you first begin raising it, you must exceed the force of gravity to accelerate the pen upwards, and in doing so net work is done on the pen (confirmed further by the fact that it has gained kinetic energy). When you stop raising it, your force is less than that of gravity, to allow it to slow to come to a stop (confirmed as the pen loses kinetic energy). Since the pen began at rest, and stopped at rest, it gains no kinetic energy in the whole process of raising it, and so no work has been done on it. When you release the pen, gravity is the only force acting (ignoring air resistance), thereby allowing it to gain kinetic energy, and so work is being done on it as it is falling, as potential energy is converted into kinetic (gravitational potential energy is really nothing more than an expression for the work that gravity is capable of doing). So, in short, in raising the pen you do work on it, but all the work is cancelled out by gravity and turned into potential energy. And net displacement is not inherent to the equation for work, only the differential displacement. Net displacement is merely sufficient for calculating work done by conservative force fields, like gravitational fields and electric fields of stationary charges. Someguy1221 08:25, 12 September 2007 (UTC)

Ah, looking at the article, I see where the confusion may have arisen. The actual definition of mechanical work is the integral equation. The two algebraic equations above it are less-than-accurate expressions that only suffice for some simple examples. Someguy1221 08:29, 12 September 2007 (UTC)

That is rather...surprising, I must say. I was taught that a change in gravitational energy equals work, but your reasoning sounds clear enough. Thank you so much for your explanation. The reason I am asking this question is because I received something similar on a test, and I wasn't sure I agreed with the way it was marked. In the test question, a worker wishes to carry 850 tiles to a roof and he can carry 10 at a time. To lift them, he stands upon a barrel and lifts the load the rest of the way, steps down, repeats 85 times. Apparently the correct answer involved calculating the work done in one load, involving the worker's mass, the mass of 10 tiles and the formula Ep=mgh, and multiplying it by 85. I'm going to have to consider your explanation and read up a great deal more on what I initially thought was a simple concept. Thank you once again! Vvitor 08:38, 12 September 2007 (UTC)

You're very welcome, but let me just reiterate...A point that should be made very clear in any homework or test question is the destiction between work done by and work done on. Work is certainly done by the worker, but no net work is done on the tiles, overall. Someguy1221 08:42, 12 September 2007 (UTC)

I tend to think of work as the amount of energy you expend transporting a test particle in a conservative field, i.e. I think of ${\displaystyle W=\Delta V=\int _{\mathbf {x} _{i}}^{\mathbf {x} _{f}}-\mathbf {F} (\mathbf {x} )\cdot d\mathbf {x} }$ as the integral form of ${\displaystyle \mathbf {F} =-\nabla V}$. This was clearly the intended interpretation in Vvitor's test question. In this interpretation kinetic energy isn't involved at all, and the work involved in transporting the tiles isn't zero. One can argue about whether the work is done on the tiles or on the field, but in any case there's a net energy transfer which is later reversed when the tiles are transported back to ground level, and W measures the amount of that transfer. -- BenRG 11:47, 12 September 2007 (UTC)

My apologies for the poor wording of the question. The worker (no pun intended) steps up onto a barrel, moves 10 tiles onto the roof of the house, steps down and repeats. At the end of the 85 loads, the 850 tiles are on the roof and the tiler is on the ground. The exact wording of the question, such as "work done by...on..." is also unclear because of my poor memory. I recall the question asking "how much work does he do". It's ambiguous, I know, but I've sadly come to expect this kind of ambiguity on physics tests. Thank you for your insight Vvitor 14:05, 12 September 2007 (UTC)

microorganisms

what are the benefits of being small to a bacteria such as E.coli in comparism to a eukaryote such as paramecium.discuss —Preceding unsigned comment added by 82.206.134.148 (talk) 07:58, 12 September 2007 (UTC)

A friendly reminder that, at the top of this page, it says: Do your own homework. The reference desk will not give you answers for your homework, although we will try to help you out if there is a specific part of your homework you do not understand. Make an effort to show that you have tried solving it first. Rockpocket 08:10, 12 September 2007 (UTC)

There's a template for that do your own homework thing. It's {{dyoh}}. — Daniel 03:00, 13 September 2007 (UTC)

Measure of temperatures

The records and the measures of temperatures are in umbra or under sun? --Vess 10:05, 12 September 2007 (UTC)

If you are talking about the weather, air temperatures are normally measured in the shade.--Shantavira| 10:44, 12 September 2007 (UTC)

The temperature of an object out there in the world depends on a balance between the energy it absorbs by conduction through the air, the input of energy from the sun and the sky - versus the energy it loses due to infrared radiation and conduction out into the air. Hence, if the sun is beating down on your thermometer, the solar input can push it's temperature up much higher than the surrounding air - and the temperature it'll show won't be the air temperature - it'll be it's own temperature. Putting it in the shade helps that somewhat by shutting off the solar input contribution - and whilst it's still absorbing a little extra energy from the sky, the temperature it reads will reflect much more accurately the energy from the surrounding air. Hence - only readings made in the shade are meaningful measures of air temperature with most kinds of thermometer. SteveBaker 13:17, 12 September 2007 (UTC)

A Stevenson screen is used to provide both shade and protection from wind chill. DuncanHill 13:27, 12 September 2007 (UTC)

Actually a Stevenson screen is specifically designed NOT to provide any wind chill protection (not that the term 'wind chill' has any good definition when not relating to clothed humans). Wind chill comes about in humans because when there is no wind, our bodies warm up a boundary layer of warm air. Our experience of (say) 10degreeC is not of air at 10degreeC touching our skin it's something warmer than that because of that boundary effect. When the wind blows, it moves that boundary layer away and we feel what 10 degreesC actually feels like - which is to say colder than it feels in still air. So "wind chill" is a downward adjustment of the temperature to a level that represents what temperature still air would have to be at in order to produce the same sensation. It's beloved by TV meteorologists - but completely bogus as a scientific measurement. So: Far from protecting any kind of boundary layer around the thermometer, you most definitely want it to be exposed to the wind in order to get an accurate measurements of the true air temperature! That's why the Stevenson screen has slats all round it to let the wind blow through the box. SteveBaker 18:40, 12 September 2007 (UTC)

GPS TIME SYNCH

HI SIR, i searched in ur wink guide about the gps but i dint find the relevant info i need...so plz do the needful.... i wan the PRO'S AND CONS how the gps has its hand on relay time synchronisation —Preceding unsigned comment added by 203.145.162.226 (talk) 10:53, 12 September 2007 (UTC)

I'm not sure I understand your question - but GPS relies heavily on time, each of the satellites of the GPS system broadcasts the time to high precision. GPS units on the ground read the time signals sent by each satellite all at the same instant. Because the satellites are all at different distances, their time signals are delayed by different amounts due to the speed of light. Knowing where the satellites are in space and the time they sent their signals allows the GPS unit on the ground to figure out where it is. Clearly, it's essential that the clocks on all of the satellites are accurately synchronised and the guys at the ground station that run the GPS system make sure that this is very precisely the case. Your GPS unit therefore has a very good and extremely accurate knowledge of the time just as a part of what it does. As for the Pro's and Con's:

• CONS:
  • A GPS unit is a lot more expensive and a lot bulkier than a wrist watch.
  • GPS doesn't work underground or inside some buildings (although the GPS unit may continue to give you the time, it won't be being synchronised with the satellites anymore).
  • The GPS system is under the control of the US military - I guess that in some applications you might be concerned about whether they might turn it off in times of war - but since an increasing number of critical systems use GPS, this is becoming less and less likely to happen as time goes on.
  • Another problem with GPS is that if the ground unit has been switched off for an extended period of time, or if it's been turned off, then moved a hundred miles and turned back on again - then it can take it quite a while to lock on to enough satellites to get a decent result. Normally, it uses its internal clock to estimate the positions of the satellites, so things go fairly quickly.
• PROS:
  • It is exceedingly accurate - to within a few nanoseconds in fact!
  • The time-zone can be generated automatically because the GPS unit knows where it is in the world.

I hope this answers your question - if not, please rephrase and clarify what you need to know. SteveBaker 13:11, 12 September 2007 (UTC)

One thing to keep in mind, if you actually need the time accuracy you can get from GPS, is that it isn't exactly the same as civil time. I think it's a UTC0 versus UTC1 difference or something like that. It appears to be roughly a half-second difference from my observation, comparing a clock synched with WWV to a GPS handheld. Admittedly it's also possible that the response time of the LCD display is different between the two instruments. --Trovatore 02:15, 13 September 2007 (UTC)

About Sinter & Pellet (copied from Village Pump (technical))

Dear Sir,

I would like to ask a question that What is the difference between Sintering & Pelletizing (Of Iron Ore Fines)?

Could you help me in this? —Preceding unsigned comment added by 122.168.70.129 (talk) 04:01, 12 September 2007 (UTC)

I am copying your question to the Science reference desk which is a better place for this type of question. DuncanHill 12:45, 12 September 2007 (UTC)

Sintering which see, is a general term for joining things (powder usually) using heat, pelletisation almost certainly refers to making pellets, which could be by sintering though other methods are possible (such as removing liquid from a solution/suspension of the fines maybe)87.102.16.32 14:35, 12 September 2007 (UTC)

note, there is an article on Pelletizing though I'm not convinced that it's written in english - take a look anyway - and improve it if you can...87.102.16.32 14:38, 12 September 2007 (UTC)

Typically iron dust is formed into balls (maybe as a wet sludge) then heated(sintered) to dry out and fix in shape. This 'sintering' wouldn't be/need to be as extreme as the sintering used in forming ceramics/cermets etc...87.102.16.32 14:50, 12 September 2007 (UTC)

Also pelletization of iron ore can use a binder see http://www.cs.akzonobel.com/MarketSegments/Mining/Pelletization.htm (which may not need sintering - just drying)

also see this diagram http://www.kudremukhore.co.in/pelpro1.htm which should give a rough idea of what happens - note the separate stages of mixing, 'balling','rolling' and heating last - 87.102.16.32 14:57, 12 September 2007 (UTC)

There are some good pages about both these subjects if you want to know more - just to a web search for either of the two terms.87.102.16.32 15:00, 12 September 2007 (UTC)

Stupid question about light reflection.

Pardon my ignorance. White objects are only white because they are reflecting all of the wavelengths of light that make up white light. But if they are reflecting all of the visible spectrum why aren't they truly reflective like a mirror? Jooler 13:01, 12 September 2007 (UTC)

Because their surface is diffuse. A mirror is specular. Capuchin 13:12, 12 September 2007 (UTC)

Because dull surfaces are microscopically bumpy - each tiny part of the surface reflects light off in a different direction - so the light is scattered more or less evenly in all directions. Very shiney surfaces (such as mirrors) are polished flat so that all of the light is reflected in one direction. Some surfaces are bumpy but have a larger fraction of the surface pointed in more or less the same direction - these are the majority of objects that show shiney highlights - but aren't as flat as a mirror. When you wax your car, you are using the soft wax to fill in the microscopic cracks and dimples in the paint - and the result is a shinier car. SteveBaker 13:25, 12 September 2007 (UTC)

Hm... But you'll never polish a white car to the point where it reflects like a mirror, and if you take tin-foil and keep on crunching it up and flattening it out, it will never look white. Jooler 18:39, 12 September 2007 (UTC)

The car has a layer of the bumpy white paint, which is then covered by a smooth layer of varnish - this is howe they can be both white and shiny at the same time. For the tinfoil, you'd need to get the surface really bumpy. While you would not be able to get it this rough by crumpling it, if you were to rub it quickly with sandpaper, it would definitely appear much whiter than it did before. Laïka 19:04, 12 September 2007 (UTC)

What a nice experiment! I just tried it with a ScrotchBrite pad and it turned the foil from reflective to dull white. I'll have to remember this one! - hydnjo talk 02:16, 13 September 2007 (UTC)

The point here is that we're talking MICROSCOPICALLY bumpy. Crumpling foil up still leaves flat bits maybe a millimeter across. I'm talking about bumps that are maybe 1000 times smaller than that. Well maintained, polished car paint DOES act like a mirror - you can easily see your reflection in it. Take a look at my 1963 Mini Image:1963 MkI Mini.jpg - look to the right of the nearest headlamp and you can see my wife's silver Mazda reflected in the green paint. That doesn't mean that the paint is reflecting all colours equally though - it may be absorbing some of it (which is why that car is green). Car paint cleanly reflects some percentage of the light (from the surface of the clear-coat) - and scatters the remainder (that penetrates through to the pigmented paint beneath). SteveBaker 02:33, 13 September 2007 (UTC)

Airspray

I have a can of airspray, which sprays out plain old air at a high pressure. The air is kept under pressure by propane, butane, and "aliphatic hydrocarbons", whatever those are. The can gets extremely cold to the touch after only minutes of continuous use. Why does this happen? JIP | Talk 14:16, 12 September 2007 (UTC)

Break out the Gas laws. (See especially Charles' law and Gay-Lussac's law.) TenOfAllTrades(talk) 14:22, 12 September 2007 (UTC)

Actually the butane and propane will be (probably) liquids in the can due to being under pressure.. releasing the valve lets these liquids boil/vapourise - which requires energy.. - shake the can - you should be able to here the liquids sploshing about.. (it is possible of course just to compress air without using the hydrocarbons.87.102.16.32 14:33, 12 September 2007 (UTC)

Those air sprays don't actually spray much (if any) air. You could theoretically pressurise air like that but the pressures would be huge and you couldn't get much into the can. Using liquids that boil at close to room temperature/pressure allows MUCH more gas to be stored without a heavy pressure vessel. But yeah - boiling those liquids takes energy and that cools the resulting gas considerably. SteveBaker 16:45, 12 September 2007 (UTC)

transistor

Misplaced Pages:Reference_desk/Computing#transitor/logic_gate_switching_energy

I asked a question over there, but someone here might be able to answer - hence the link.87.102.16.32 14:48, 12 September 2007 (UTC)

Coprolalia - How does person learn the obscenes words?

I posted on the talk page to suggest it should be in the article, and then thought, why not look here? Sorry if this should be in language - but I'm more interested in how certain words are "plucked out" and then used by someone with Tourettes Syndrome or something else. However, it could also be a question of language, becasue you can't use words you don't know.

My question is, okay, someone with this will automatically start using taboo words, right? But, what if they have never *heard* the taboo word in question. They can't use a word they don't know.

I'm presuming, of course, that it works this way - say I know someone with TS who has never heard ****, putting 4 stars to mean a generic curse word. He hears it, I act shocked, and so he figures it's taboo. Does the part of his mind that says not to say it then turn off, or what?

Granted, it's hard nowadays to grow up and never hear a curse wrod, but that actually brings to mind a related question. What about someone growing up in an environment where the words are *not* taboo, like some inner cities where every 2nd word is ****? Does this person then *not* say the taboo word becasue where they've grown up, they haven't learned it is taboo?

I think the first may relate to why only a minority of people with TS use coprolalia, and maybe the 2nd does a little. I've alwyas thought the stigma of someone like that always using it was dumb becasue it ignored the basic rule of language I cited above - you can't use words you've never heard. But, I'm curious as to how that happens, and also how it's effected by a culture in which the certain words aren't taboo. Would a child of bizarre parents who taught him that the word "table" or "chair" is taboo shout "table" or "chair"? 209.244.187.155 15:56, 12 September 2007 (UTC)

Yes. Edison 16:07, 12 September 2007 (UTC)

Maybe it is the society which perceives the disease, and not the individual who has the disease. Anyway, I think any introduction to Psychology will quickly make it very clear that social norms are always relative to the surroundings. Nimur 16:21, 12 September 2007 (UTC)

Or cultural anthropology, for that matter. Shakespeare in the Bush is a classic account, IMHO. --Kjoonlee 18:26, 12 September 2007 (UTC)

Seal identification

Hi, can someone tell me what species this seal belongs to, please? I suppose it's an earless seal of some sort, but I think this image would be a nice addition to the relevant species article. --Kjoonlee 17:24, 12 September 2007 (UTC)

• It looks a lot like this Common Seal here: . That said, they all kind of look the same to me. --Sean 18:53, 12 September 2007 (UTC)

• I agree with Sean that it is a Common Seal (or Harbor Seal) Phoca vitulina.--Eriastrum 19:33, 12 September 2007 (UTC)

Regeneration of limbs

I've heard, from two seperate sources, of a young boy who was very interested in Salamanders and such creatures who could regeneration limbs. The boy then was involved in an accident which caused him to lose a leg (or an arm, not sure) As he'd witnessed the regeneration of limbs with Salamanders, and no one told him otherwise, he believed that he could also grow a new leg. No one contradicted him, and in time this is exactly what he did. One of the people who told me this say they saw photographs of this, in stages, on the web. I have, despite numerous searches of various sites, never found such a thing. Has anyone out there seen or heard of this? It sounds the stuff of sciencfiction, but one person who swears this is true is usually a sane and sound person? —Preceding unsigned comment added by 159.134.229.90 (talk) 20:08, 12 September 2007 (UTC)

This is definitely false because other then the biological impossiblity, if he had happened believe me it wouldn't be hard to find stuff about it. Definitely the mind can have a major affect on your health, see Placebo effect but it is most definitely not capable of causing the regeneration of a limb Nil Einne 20:46, 12 September 2007 (UTC)

Sorry, why is this a biological impossibility? If lizards can re-grow tails, if salamanders can re-grow limbs, and if humans can re-grow tonsils, why would it be an utter impossibility to re-grow limbs? Just because it's never been documented it doesn't mean a declaration of impossibility is appropriate. Impossible is a rather strong word. Vranak 01:38, 13 September 2007 (UTC)

It'd be more accurate probably to say there's no known way this can happen. Friday (talk) 02:43, 13 September 2007 (UTC)

Agreed. Vranak 03:03, 13 September 2007 (UTC)

I was unable to find mention of this on snopes, but as said above- if this had actually happened we'd expect it would be major news. Since it's not... Friday (talk) 20:58, 12 September 2007 (UTC)

Somewhere I read that limb regeneration in mammals is prevented by scar formation. If scarring can be stopped, far more regeneration could take place (but at a slower healing rate than with a scar). Graeme Bartlett 02:07, 13 September 2007 (UTC)

But if this had happened, it would be REALLY common knowledge - it certainly wouldn't be hard to find. I don't believe it. SteveBaker 02:28, 13 September 2007 (UTC)

Most of the people here on the reference desk have grown a limb or four at some ealier stage in their life, so it is known that humans can do it. It is under the circumstances of the OP that this is not possible (after amputation). And will to regrow a limb would make no difference either. Stem cells for regrowth are found in the finger nail bed. But how can you make them grow a whole arm, that is the tricky part. Graeme Bartlett 02:40, 13 September 2007 (UTC)

It sounds like a fiction children's book to me. Reminds me of a Paul Jennings one where a boy grows back his finger repeatedly. Aaadddaaammm 03:40, 13 September 2007 (UTC)

terms related to livestock management (Spanish translation)

How do you translate into Spanish the following terms: - Stockbook =  ? - Stud enterprise =  ? - Register stockbook =  ? —190.66.253.179 21:16, 12 September 2007 (UTC)

This isn't really a question for the science desk - may I suggest you ask at the language desk instead? SteveBaker 03:40, 13 September 2007 (UTC)

Genetic Relatedness of the Human Species?

I recently read that a new study shows that human beings are less related to each other than was previously thought. I was wondering how this new data effects other scientific data regarding human genetics. For instance it had been thought that modern Homo Sapiens branched off from archaic Homo Sapiens about 225,000 years ago. Since that date is based on calculations involving genetic relatedness is that date still accurate? Similarly is it still true that Caucasoids branched off from Negroids 110,000 years ago and that Mongoloids branched off from Caucasoids about 40,000 years ago? 207.69.139.139 21:44, 12 September 2007 (UTC)

These dates would have been estimated by looking at the vaiations in a small number of genes. By considering more and more genes a more accurate estimate could be made. However just because there is a great deal of variation accross people does not mean that the branch point is different. The variations could have been in the population the whole time, and the variations could be in genes that do not matter in a negative way whether or not they differ. What it means is that whole (or a big sample) of populations of people need to be compared with each other to estimate a divergence point, rather than considering one sample individual. Graeme Bartlett 02:05, 13 September 2007 (UTC)

If I'm understanding you right - I think there is a misconception. You said "The variations could have been in the population the whole time" - but that's not possible. At the point of a genetic mutation - all of the offspring that carry the mutation are descended from a single individual (although possibly with more than one mate - but you can eliminate that issue by using mitochondrial DNA). That sharply limits the diversity of the gene line from that point onwards. So, for example, at the point where Homo Sapiens split from the rest of Hominidae, one creature and one only had the mutated gene that made them different from the other great apes. Every single one of us is descended from that one individual. That's why this genetic distance thing works. If we had the genetic map of that individual, we could count the number of differences from that in the 'junk' DNA and because this has nothing to do with evolution and those differences happen at a reasonably predictable rate, we could estimate the elapsed time since that common ancestor. However, we don't have the DNA from that individual - so we have to deduce what it's DNA was like by examining the junk DNA from a lot of modern people and analysing the patterns of mutation to figure out what our common ancestors DNA must have been like. The reason our number for that is approximate is because we keep finding more individuals with new differences in that area of their DNA and that fact pushes the date of that last common ancestor back or forwards in time. But there is no ambiguity - every single change has happened since that common branch point. SteveBaker 02:26, 13 September 2007 (UTC)

September 13

The Body's Capacity & Ability To Die

Any input is appreciated. Thanks. Let's assume that we have an "average" person (whatever that means ... average age, height, weight, health condition, etc. etc. etc.) And this person wants to die (i.e., "passively" commit suicide). Let's assume that there is nothing at all wrong with his mental health ... that is, he is not suicidal / depresssed -- but, rather, that this is simply a medical experiment. Say that this person simply goes somewhere (let's just say, he goes and lays on his bed) and he simply stays there. Never, ever leaves the bed. (For illustration, we can add the fact that he is restrained / handcuffed / etc. -- although that is irrelevent, I think.) The location of the bed is essentially irrelevant -- but I want it to be a controlled environment (like his bedroom) -- as opposed to outside in the desert or a mountain or the ocean or his back yard or the highway or whatever (where contending with the elements and/or with intervention of other humans/animals is an issue). This person affirmatively does absolutely nothing -- does not eat, drink, medicate, etc. -- he just passively lays on the bed ... and (perhaps) his body naturally / passively excretes or sleeps or whatever a human body would passively do. About how long would it take for him to die? I assume that the cause of death would be lack of water / dehydration --- is that correct? (I have always heard that when you are lost or deserted or abandoned, the critical health worry is lack of water.) If so, what exactly would happen to his physical body that would cause the body to die? In other words ... no water enters his body ... and then what ... so what? What is the reaction of the body, at this point? Finally: if the person were unrestrained and free to move about (no handcuffs) ... would his physical body (and/or his mind) somehow "force" him to seek water/food/assistance/ at some point? In other words, does the body have some type of defense mechanism that will force the guy -- whether he wants to or not -- to extract his body from danger and seek survival (i.e., food, water). Restated, perhaps: which would "trump" the other ... his (mental?) willpower to die or his physical body's natural / reflex / defense mechanisms to survive? (if the latter even exists). Thank you. (Joseph A. Spadaro 02:32, 13 September 2007 (UTC))

Yes the restrained guy would die of thirst. But I would expect the thirst and hunger to overcome the will to die (if the person is in normal health and psycology). Graeme Bartlett 02:36, 13 September 2007 (UTC)

Exactly as with your previous question - you are asking a very contrived hypothetical fenced-around-with-caveats question. What makes you think that anyone would have ever studied such a thing? If they haven't (and it's pretty certain that no such study has been or ever (ethically) could be done) - then how on earth do you think anyone can come up with an actual answer? You're just going to get another bunch of complaints about the question and (possibly) random speculations! SteveBaker 03:23, 13 September 2007 (UTC)

Murder Victim's Multiple Stab Wounds

When reading news accounts of a crime, I often see things like this: "the medical examiner states that the victim was stabbed 128 times" (or some such). How in the world do they calculate that number? I don't understand. Not to be crude -- but -- when a body has been stabbed umpteen gazillion times, what in the world can you distinguish? Isn't it all just one big "glob" of a mess that would be impossible to sort out? Yet, they always seem to have the exact, precise number -- how is that? Any insight is appreciated. Thanks. (Joseph A. Spadaro 03:16, 13 September 2007 (UTC))

Once the body is cleaned, assuming it hasn't been completely mutilated, it wouldn't be that hard to make out individual wounds. Someguy1221 03:34, 13 September 2007 (UTC)

Besides, I don't think I ever heard of a number as big as 128 - it's usually less than 20 and even then you tend to hear things like "at least XX" - meaning that they counted XX holes but they aren't sure whether some of the holes represent multiple stabbings. SteveBaker 03:37, 13 September 2007 (UTC)

Imported energy

what is The share of energy resources used by the United States that comes from other countries? —Preceding unsigned comment added by 71.98.105.119 (talk) 03:35, 13 September 2007 (UTC)

pneumonia vaccine

I've never heard of a pneumonia vaccine but I got one today. Are they supposed to swell up like I've been lifting weights all my life and burn like crazy plus make my arm and shoulder sore? I had a flu shot and it was pain free compared to this. Clem 04:40, 13 September 2007 (UTC)