Wikipedia:Reference desk/Science

Wikipedia:Reference desk/headercfg

September 3

Localized buckling

What exactly is localized buckling? deeptrivia (talk) 00:47, 3 September 2007 (UTC)

It's when a surface that should be flat looks something like this:

           ______ 
→________/       \_________←

This can be caused by many things, such as:

1) Greater thermal expansion of the surface material than the underlying material (or greater thermal contraction of the underlying material), due to a different coefficient of thermal expansion for each material.

2) Compressive forces in the directions shown.

Such buckling may be a warning sign of imminent failure of the object in question. StuRat 01:26, 3 September 2007 (UTC)

Mathematically, how is it different from the usual buckling? deeptrivia (talk) 02:25, 3 September 2007 (UTC)

Presumably it's a qualitative description indicating that the fault is localized to a specific area or material defect. Nimur 02:54, 3 September 2007 (UTC)

(Incidentally, is there a reason why our article on qualitative research exclusively mentions the social sciences?) Nimur 03:02, 3 September 2007 (UTC)

It's just in a small portion of the structure, versus over it's entire length. A local defect, such as partial delamination of the layers, may be why you get localized buckling instead of buckling over the entire length. Localized buckling can actually be worse, as the forces act on a small portion of the structure, which may fracture, while, if they acted on the entire structure, it could withstand those forces. StuRat 02:57, 3 September 2007 (UTC)

I guess both localized and "global" buckling would correspond to a singularity in the stiffness operator of the system. Is there a way, then, to tell one from the other looking at the bifurcations of the system? deeptrivia (talk) 04:40, 3 September 2007 (UTC)

Amalgam Illness

What is the incidence of mercury poisoning in the United States? —Preceding unsigned comment added by 151.204.143.134 (talk) 02:11, 3 September 2007 (UTC)

"Mercury poisoning is listed as a "rare disease" by the Office of Rare Diseases (ORD) of the National Institutes of Health (NIH). [1] This means that Mercury poisoning, or a subtype of Mercury poisoning, affects less than 200,000 people in the US population" [2] Rockpocket 02:44, 3 September 2007 (UTC)

Given the title of this question you may also be referring to the Dental amalgam controversy. As best I know the general scientific consensus is that amalgam use has no significant side-effects in most cases. However this article gives a boatload of potentially useful references. --jjron 08:03, 3 September 2007 (UTC)

As the article states, it is a bit of a controversy to say the least. Some folks claim that everyone with amalgam filling ends up with the mercury in their system sooner or later. Other folks claim that it's all bogus. If the pessimists are right, however, then anyone with an amalgam filling would get mercury poisoning at some point in their lifetime, and therefor the incidence would be pretty close to 100% in certain age groups. Of course, amalgam isn't the only source of mercury (poisoning or otherwise). I expect that many older physics/chemistry teachers might have it, I had a few teachers who enjoyed playing with mercury in class, and if you do that often, poisoning is pretty much inevitable. There are also truths and rumours of mercury in the drinking water supply in some areas, which is potentially another source. That being said, amalgam is outdated and should not be used, regardless of mercury poisoning. There are superior alternatives out there, which last longer, look more natural, and are a lot less likely to poison you. I think that "glass carbomer" is the type of filling most recommended by amalgam-haters. I'm doing my best not to be too opinionated here, but I most humbly apologise if I fialed. Nimlhûg 10:44, 3 September 2007 (UTC)

You're casting an awfully wide net there. As far as I know, the ideal body burden of mercury is zero, and we all have more mercury than that. If that's "poisoning" then everyone is poisoned. But I think the question is more along the lines of how many people have identifiable symptoms that can reliably be associated with mercury. --Trovatore 17:26, 4 September 2007 (UTC)

An interesting case to check is comic writer Kurt Busiek, who, by a staggering coincidence, contracted mercury poisoning shortly after working on Amalgam Comics. Matt Deres 16:35, 5 September 2007 (UTC)

Entomology Question: Identifying Insects

Does anyone know what species these insects are? [3], [4], [5]. The pictures were taken in a backyard in a suburb of Southern California. —Preceding unsigned comment added by Schmoov (talk • contribs) 04:31, 3 September 2007 (UTC)

First two look like weevils from there I don't know.87.102.47.218 14:13, 3 September 2007 (UTC)

The first guy has the typical "true bug" markings of the order Hemiptera, but more specific than that I cannot be. --24.147.86.187 15:51, 3 September 2007 (UTC)

They are definitely "true bugs" (Order Hemiptera), not weevils, which are beetles. The leaf-like expansion on the hind legs distinguishes it as one of the Leaf-footed bugs in the family Coreidae. It is possibly Leptoglossus occidentalis a pest of conifer trees in California. The adult sucks the sap of pines and incense cedars. It neither bites nor stings. It defends itself by emitting an unpleasant smell. Try an image seach on google and see what you think. In your 3 photos, the reddish ones are presumably the immature nymphs (not larvae, Hemiptera do not have a complete metamorphosis).--Eriastrum 18:31, 4 September 2007 (UTC)

The nymphs are definitely assassin bugs. See this image. — Quin 02:10, 5 September 2007 (UTC)

Hmm, although I have just had correspondence with an entomologist who says that they're leaf-footed bugs (Leptoglossus occidentalis). The Wikipedia article on assassin bugs may have the wrong image. — Quin 04:58, 5 September 2007 (UTC)

Quin, I think you are right that the image of assassin bug nymphs in the wikipedia article is incorrect, and that it is of leaf-footed bug nymphs. If you notice, the nymphs have a very small enlargement on their hind legs that assassin nymphs do not. It might be a good idea to remove the nymph image from the assassin bug article. --Eriastrum 16:32, 5 September 2007 (UTC)

Pepper remains in the system for about 7 years...

Over the years I've heard a couple of times from different people that apparently pepper stays in the system for about 7 years- that it doesn't get digested or something.
There's nothing on snopes.com, theres nothing in Black pepper or its talk page, and nothing comes up on google - is there any truth to this claim? Can pepper be eaten liberally? Rfwoolf 08:52, 3 September 2007 (UTC)

I heard the same 7 year figure for chewing gum. I'm guessing it's an urban myth, but I have no evidence either way. —Pengo 13:41, 3 September 2007 (UTC)

Things which are not digested just pass through with your next bowel movement. (Hence sometimes you can "identify" things that didn't digest correctly. Bleh.) I would beware of any claims that various foodstuffs are not digested and somehow linger in your system (where would they linger?), they sound like old wives' tales. That which applies to chewing gum almost certainly applies equally to black pepper. --24.147.86.187 15:55, 3 September 2007 (UTC)

Pepper consist of hundred thousands of different types of chemical compounds - which one are you talking about (piperine?) Your body uses food compounds or their metabolites as building blocks, so, for example, calcium from pepper will end up in your bone and might stay there your whole life. But pepper is definitely not special in that respect. You might want to read digestion, metabolism, drug metabolism, and excretion. Cacycle 02:19, 4 September 2007 (UTC)

Eucalyptus as a source of gun powder

It is said to our Reasearch class that Eucalyptus leaves can be a source of gun powder. Some evidences are when a forest fire occurs, firefighters are hearing some little explosions that they found out that little explosions were bought by Eucalyptus trees. I found out that Eucalyptus leaves can be a source of gun powder, but are there bad effects when used?WikiPoTechizen 09:53, 3 September 2007 (UTC)

Those bangs are due to heat from the fire boiling up steam in a confined space that then breaks up its confines with a bang. Charcoal from the burnt wood could be used as part of the formula for gun powder, but don't expect to find oxidizing substances or sulfur in Eucalyptus. Graeme Bartlett 10:03, 3 September 2007 (UTC)

I mean what are the possible components of Eucalyptus that can easily burn up? Eucalyptus oil?--WikiPoTechizen 10:40, 3 September 2007 (UTC)

1. Yes, eucalyptus oil is flammable.
2. However, being flammable is not sufficient to make something an explosive. An explosive must also contain an oxidising agent.
3. Gunpowder is not a single compound. It is a mixture of three different substances.
4. As Graeme Bartlett said, you won't find all of these three substances in Eucalyptus trees.
5. So, no, Eucalyptus trees are not a source of gunpowder. Gandalf61 13:16, 3 September 2007 (UTC)

Thank you for your information. —Preceding unsigned comment added by WikiPoTechizen (talk • contribs) 11:05, 6 September 2007 (UTC)

Contaminating Water Supplies

Just a question, with all of the Terrorist activity going on, They keep telling us that major supplies of water can not be contaminated, since it would become so dilute. But what about five pounds of ionized mercury, easily obtainable, or Dioxin, a byproduct of bleaching paper, also being the most carcinigant molecule know to exist?? I don't know if we are being told the truth both methods would seem to permantly polute a large watershead. P.S. If this is inapropriate delete it! Note that mercury is becoming extinct from the U.S. public example try to by a mercury thermometer, they have been around forever. Second mecury containing deviced have been replaced in hospitals, due to Pollution?..--Aaron hart 11:31, 3 September 2007 (UTC)

I'd say it's possible, but most terrorists want to kill people immediately, and make it obvious. Eventual deaths from cancer that may or may not be due to the contamination just wouldn't suit their preferences or serve to recruit more terrorists. StuRat 14:07, 3 September 2007 (UTC)

Look at the numbers. The Lake Joe Pool reservoir near where I live contains 618 Billion liters of water. The average person drinks between 1 and 7 liters per day - but that's not all going to be from the same public water supply - let's be generous though and say that the reservoir contains enough water for 100 Billion people for one day. That means that to cause people to die from drinking the stuff, you either need to dump 100 Billion times the lethal dose of whatever poison it is into the lake - or you have to put in enough of a cumulative poison so that it accumulates in the body. However, in the height of summer, 30 million liters are taken from the lake each day - which serves about 15,000 people. So of the 30M liters, only at most 100,000 liters of that is ever actually drunk - the rest is used by industry, for flushing toilets and filling baths or for lawn watering. So the amount of a cumulative poison would have to be spectacular if it was going to make it into the population fast enough. Also, the water coming from the lake is tested at least daily - so a cumulative poison would have to be administered very slowly in order to keep it in a low enough quantity to go unnoticed. Hardly a great terror weapon. As for Dioxin - a back-of-envelope calculation says that if you dumped a couple of 50 gallon drums of the stuff into such a lake, the resulting dosages for the surrounding population would be comparable to their lifetime dosages from eating farm-grown food in the USA. I very much doubt that anyone would notice - let alone be terrorized by it. That's not to say one shouldn't worry. If that much was dumped in right next to where the water is pumped out ready to be purified and sent off to people's homes - then the concentrations would be much higher...but that's not a simple thing to do without getting noticed doing it. A truck bomb in a crowded city center is a much more direct and vastly simpler terror weapon. SteveBaker 00:13, 5 September 2007 (UTC)

It could be argued that the 9/11 hijackers did both. Not only did we feel the immediate effects, but we're now beginning to see deaths and injuries from mesothelioma and other diseases caused by the asbestos-laden clouds of dust. The injuries from this have the possibility of being worse than the original building collapses... and yet nobody really feels terrorized by it. --Mdwyer 00:57, 5 September 2007 (UTC)

Picture

Who is the person in the picture behind Gell-Mann here ? Tintin 10:10, 3 September 2007 (UTC)

Ludwig van Beethoven.--Rallette 10:33, 3 September 2007 (UTC)

Thank you. Looked very familiar but couldn't place it. Tintin 10:37, 3 September 2007 (UTC)

i don't understand when you check the photos link, there are at least five people who state that it it Beethoven, so why ask?? —Preceding unsigned comment added by Aaron hart (talk • contribs) 11:05, 3 September 2007 (UTC)

In the flickr link ? I can't see it at the moment anyway because I am at work and it is blocked here ! Tintin 11:16, 3 September 2007 (UTC)

yes, my appologies--Aaron hart 11:33, 3 September 2007 (UTC)

Speed of Butterfly

When a butterfly fly in a bus. the bus run @60KMPH. Now what is speed of butterfly? —Preceding unsigned comment added by 203.197.157.138 (talk) 12:48, 3 September 2007 (UTC)

Not enough information. You don't say how fast the butterfly is flying relative to the bus, and in which direction. —Keenan Pepper 13:04, 3 September 2007 (UTC)

The velocity of the butterfly relative to the bus is the same as it's velocity relative to the ground would be if it was outside. It's velocity relative to the ground is the vector sum of the bus velocity and it's velocity inside the bus. So, if the butterfly is moving 5 kph inside the bus, in the same direction as the bus, it's moving 65 kph relative to the ground. If it's going the opposite direction of the bus, it's velocity is 55 kph relative to the ground. StuRat 14:00, 3 September 2007 (UTC)

Uh Sturat, what's the frame of reference, the Earth? I say the butterfly isn't moving at all. I'd make him the frame of reference. :) --Cody.Pope 16:17, 3 September 2007 (UTC)

He said "velocity relative to the ground." -Elmer Clark 01:14, 4 September 2007 (UTC)

StuRat said relative to the ground. Not anon. I'd make an Ultra-high-energy cosmic ray the frame of reference. Then it's one fast butterfly. — Daniel 03:10, 4 September 2007 (UTC)

(But it does explain how one flap of it's wing causes a hurricane on the other side of the planet! :-) SteveBaker 23:36, 4 September 2007 (UTC)

I see, next time I'll read more carefully. Haha. --Cody.Pope 13:09, 4 September 2007 (UTC)

How could cat kill a rabbit?

My cat is constantly bringing home dead baby rabbits. My question is above - I mean, a cat's mouth is far too small to break a rabbit's neck, and I don't see how it could choke one either. I suppose it could shake the rabbit's head until it had a brain haemorrhage, but probably not. EamonnPKeane 13:02, 3 September 2007 (UTC)

Rabbits are easily spooked, either by the cat or something like a lawnmower. Maybe the cat is just running off with unprotected baby rabbits? -- JSBillings 13:05, 3 September 2007 (UTC)

Yea, the mother rabbit probably flees. Rabbits reproduce so rapidly it doesn't make evolutionary sense for the parents to risk their lives to save the lives of their offspring. The cat can probably bite the baby rabbits right in half. StuRat 13:54, 3 September 2007 (UTC)

Don't underestimate a cat's ability to break the neck of a small mammal. Cats are pretty good predators and know what they are doing. (Dogs too, I might add.) --24.147.86.187 15:45, 3 September 2007 (UTC)

Also don't underestimate the size of a cat's yawn; I can't imagine a wild rabbit neck that that wouldn't fit in there! jeffjon 18:14, 4 September 2007 (UTC)

Cats can use a claw or their teeth to cut the throat of a small mammal. They can also possible strangle a small mammal by gripping the back of the neck fur tightly, or break the neck by biting (not necessary to get the whole head in the cat's mouth. A bite through the skull would also be a way of killing. Dogs will grab the head and shake the animal to break the neck;not sure if this is also a cat trick. Cats (and dogs) are also good at finding small dead animals and bringing them home as if they had killed them. Edison 18:58, 3 September 2007 (UTC)

Is it an urban myth that cats can kill by 'sucking the breath' out of their prey's lungs? Some sort of 'kiss of death'? I've seen cats kill small mammals before but I've never seen them do that. Just to raise the gull quotient of this thread, I have seen large gulls killing mice by breaking the neck with a bite, or shaking 'till it snaps. Not just a cat thing. --Kurt Shaped Box 19:06, 3 September 2007 (UTC)

They don't suck the breath out of lungs, that's preposterous. They have sharp little claws and teeth and can use them with expert precision. That's surely enough. --24.147.86.187 20:59, 3 September 2007 (UTC)

I believe that legend started by saying they suck the breath out of babies when they are asleep. The reason was that babies would have milk on their mouths and hungry cats would lick their lips. Not knowing what they were doing, scared parents thought up the legend. StuRat 02:53, 4 September 2007 (UTC)

My nanna (she who raised me) told me that a stray cat got into the house and tried to 'smother' me when I was a baby. Apparently, the thing was over my face (though granted, it may have just been trying to sleep in my cot). She chased it off me, cornered it and killed it with a hot poker. True story. This may have been what could be considered excessive force. --Kurt Shaped Box 16:58, 4 September 2007 (UTC)

Yea, I think she would get arrested for cruelty to animals these days. The cat was probably just seeking warmth, they are masters of finding the warmest and coolest spots. StuRat 17:38, 4 September 2007 (UTC)

I don't think she's ever heard of the 'cats sucking the breath out of babies' thing - but she does certainly believe that 'cats hate babies'. She's mentioned to me several times about how cats should never be left alone with them. I guess that it's probably based on the same superstition. --Kurt Shaped Box 18:11, 4 September 2007 (UTC)

It's probably not a good idea to leave any animal with a baby, as they could harm the baby accidentally by sleeping on it (for warmth). I could possibly imagine a house pet being jealous of a baby, but plotting to murder the baby seems beyond their capabilities. I can see dogs seeing a baby as prey, but not cats, since they don't hunt anything nearly that big. StuRat 18:35, 4 September 2007 (UTC)

They catch adult rabbits too.Polypipe Wrangler 00:44, 4 September 2007 (UTC)

Lions and other big cats can kill prey by suffocation: placing their mouths around a prey animal's nose. Not sure a house cat could do that. Delmlsfan 02:43, 4 September 2007 (UTC)

I don't think that's how they do it. When lions (or cats) suffocate prey, they do it by strangulation, not by covering the nose/mouth. It'd be pretty hard to achieve a good seal on a struggling wildebeest and a lot more efficient to clamp down on the windpipe. Probably safer too, since even herbivores can deliver nasty bites. As far as cats and rabbits go, I'd guess that an adult rabbit is about as large an animal a domesticated cat would likely try to bring down, but it's hardly an amazing feat; cats are superbly adapted to catching and killing small animals. Matt Deres 14:29, 6 September 2007 (UTC)

Not a rabbit but close; I had a guinea pig once who just dropped dead, presumably of fear?, upon being sniffed by a dog. No rough contact whatsoever.Gzuckier 15:24, 4 September 2007 (UTC)

I read about something similar in rhinos and hippos once. Scare them too much and they have some sort of adverse reaction to their own adrenaline (sorry, I can't be more specific - and I *do* read a lot of crap, so this may be crap!) and drop dead. Apparently, chasing them in a truck whilst firing a few round from an AK-47 over their heads will do it. If anyone knows what the hell I'm talking about, please elaborate... :) --Kurt Shaped Box 16:54, 4 September 2007 (UTC)

A bite through the skull would also be a way of killing. - this method of killing is unique to Jaguars, insofar as I am aware. See Jaguar#Hunting_and_diet Raul654 18:17, 4 September 2007 (UTC)

Boxes under a Spitfire's wing

I recently visited the Science Museum (London), the collection of which included large parts of several Supermarine Spitfires. I noticed a structure on the underside of both wings which wasn't explained by the displays.

The museum's version had two (apparently identical) structures, on on the underside of each wing. Each is a squarish box located inboard of the wheel well, toward the rear of the wing's undersurface. It's open to both the forward and rear direction, and the rear half of it articulated, forming a kind of flap. So clearly it's intended for air to pass through it. Due to the orientation of the museum's display it wasn't possible to look through the box to see what, if anything, might be inside that space. The boxes are visible on this photo of another spit.

Here is a photo of a Spitfire with the box clearly visible, but where the museum's aircraft had identical boxes on both sides (as in the first photo), the second picture shows only one, with a dissimilar narrower structure on the other wing. The Hawker Hurricane appears to have a similar device (centrally located under the fuselage) as seen in this model, and this diagram of a Focke-Wulf Fw 190 shows a vaguely similar port which appears to be for a turbocharger.

Supermarine Spitfire variants talks about some spits that had "two stage" superchargers, others that had "one stage" ones. Are these boxes for the supercharger? If so are the-two box spits those with the two-stage superchargers? Where was the supercharger itself located? Surely you'd want it as near to the aircraft's centreline as possible, to reduce angular momentum for rolling, and if indeed it was in the fuselage then why didn't the aircraft have a single central scoop like the Hurricane or the Fokker? -- Finlay McWalter | Talk 17:05, 3 September 2007 (UTC)

I'm no plane expert but aren't all those boxes air intakes for the engine?87.102.47.218 17:47, 3 September 2007 (UTC)

Correction the 1 or two boxes are air intakes for radiator cooling (that's for the spitfire) - it's likely the same for the others....87.102.47.218 18:00, 3 September 2007 (UTC) see here [[6]]

The supercharger is connected to the crankshaft - as you would expect - I'm 99% certain of this. Ignore- thinking of something else.

Why the thing is off centre I've no idea...87.102.47.218 18:02, 3 September 2007 (UTC)

There was normally two on each spitfire. One is the water radiator. The other is the oil cooler. It is possible that the water radiator and oil cooler were adjusted to be the same size on later models. Originally, one was about three times wider than the other. See this for a ref. Under the image, it points out that one is the water radiator and the other is the oil cooler. -- kainaw™ 23:36, 3 September 2007 (UTC)

In the ref you gave - the picture [[7]] only has one intake —Preceding unsigned comment added by 87.102.21.232 (talk • contribs)

According to this page, the Mk V used round oil coolers. -- kainaw™ 23:38, 3 September 2007 (UTC)

atoms

where was G .Johnson Stonely born? —Preceding unsigned comment added by 195.189.181.130 (talk) 17:16, 3 September 2007 (UTC)

That name provides no Ghits, could you be more specific about whom this individual is? Rockpocket 18:33, 3 September 2007 (UTC)

Since that name gets absolutely zero google hits as spelled, I'm not sure that's an answer anyone is going to have. Maybe you got the name wrong? Maybe you can give us more information? --24.147.86.187 18:34, 3 September 2007 (UTC)

Eric Henry Stonely Burhop?[8].Aaadddaaammm 22:49, 3 September 2007 (UTC)

... was born on 31 January, 1911 in Hobart. [9] Rockpocket 23:30, 3 September 2007 (UTC)

With a surname like Stonely, it's more likely he's from either Nimbin or Griffith. :) -- JackofOz 13:44, 4 September 2007 (UTC)

Appearance of computer screens on television

Why is it that when computers are seen on-screen on the TV (say on the news), the computer screens flicker rapidly? They don't seem to appear like that in films or TV entertainment programmes. Is this just a phenomenon with British TV or does it happen with other countries' television networks? Rusty2005 18:49, 3 September 2007 (UTC)

Aliasing because the sample frequency of the television is close to the sample frequency of the monitor. UK television samples at 50 Hz. Depending on the montor, the difference between the TV sample rate and the monitor refresh rate is seen as flicker. --DHeyward 19:11, 3 September 2007 (UTC)

The computer monitors (CRT monitors, more specifically) draw the image line by line, starting at the top of the screen and going down, over and over again (between 60 and 120 times per second or so). When a point on the screen gets passed by this sweep, it lights up brightly in its appropriate colour. Then it starts to fade, and by the time it gets drawn again, it has faded considerably. So it does actually flicker quickly, but the human eye smears this out so when you look directly at the monitor, you don't notice. The electronic eye of a TV camera does not smear it out, however. When it captures an image (about 25 times per second), it sees the computer monitor as it happens to be at the moment – some areas shine brightly (because they have been recently drawn) and some are darker. (Try this with an ordinary still camera to see what I mean.) Sometimes, it might so happen that the computer monitor has completed precisely one full sweep (or two, or three…) by the time the TV camera takes its next image. If so, you (watching the TV programme) would see a steady image on the computer monitor (some areas bright, some dark). If the computer monitor completed one full sweep (or two, or three…) and then some, you would see the bright-and-dark pattern roll across the screen. It might also happen that the screen completes one (or two, or three…) and a half sweep before the camera takes its next image. Then the bright-and-dark pattern will have progressed half-way across the screen between the images, causing a big change in what parts are bright and dark. This you see as flicker. It repeats 12,5 times per second (every other image) in this example, which is too slow for the eyes to smear it out, so you actually see it. Did it help? Well, I tried. Actually, older TV cameras (many of which are still around, I'm sure) take the images in a sweeping fashion as well, but the principle remains. —Bromskloss 19:47, 3 September 2007 (UTC)

Add to this that it is possible to match the rate that the pictures are taken with the rate that the screen is being drawn, resulting in a steady image as described at the beginning of Bromskloss's description. This is quite tricky and time consuming though, so if you're just filming a quick spot for the news, it's not really worth sorting out. You can also avoid the problem by putting the image in later. Skittle 22:12, 3 September 2007 (UTC)

And old cell phone video camera I had had a special setting for recording computer/tv screens that eliminated the flicker. Any idea how it worked? There were no tricky or time consuming steps to it...Someguy1221 00:06, 4 September 2007 (UTC)

Perhaps just setting the exposure length of each frame to a multiple of the typical refresh interval of such screens? TV screens tend to flicker at 50Hz (PAL/SECAM) or 60Hz (NTSC), so an exposure length of 0.1 seconds ought to work for most TV systems, as well as most common computer screen refresh rates. It's also close to the kind of frame rates I'd expect of a cell phone camera. This is just a random guess, though. —Ilmari Karonen (talk) 02:36, 4 September 2007 (UTC)

Isn't that what multimeters do to cancel out the ubiquitous disturbance from the power grid? —Bromskloss 07:08, 4 September 2007 (UTC)

As for movies showing TV or computer screens, they typically digitally add in the program later, flicker-free, rather than use an image recorded by a TV camera. Since computer screens in movies only have about 10 lines of text on them, they'd have to go out of their way to make a computer do that, anyway. StuRat 02:42, 4 September 2007 (UTC)

Thanks everyone, I'd always wondered that! Rusty2005 13:25, 5 September 2007 (UTC)

When you see TV screens on a TV show, the eliminate the flicker by syncing the TV's refresh to the camera. It is my understanding that TVs used in TV newsrooms and such have an additional input to receive the sync signal. Everything in the room is basically running off the same clock. —Bradley 03:55, 6 September 2007 (UTC)

And, of course, more-modern display technologies like liquid crystal displays and plasma display panels don't flicker like CRTs did, so there's no longer any need for fancy synchronization or 24 FPS video or any of that tricky stuff.

Atlant 12:55, 6 September 2007 (UTC)

Moon Visible Daytime

It is now 1200 P.M. in Spokane, Washington the sun is high above the horizon, why is it only half the moon is visible?67.185.27.163 19:03, 3 September 2007 (UTC)

You only see the part of the Moon that is illuminated by the Sun at the moment. —Bromskloss 19:14, 3 September 2007 (UTC)

We have an entire article on Lunar phases. This will explain the process very thoroughly. Nimur 19:34, 3 September 2007 (UTC)

The other half of the moon has taken Labor Day off. --24.147.86.187 20:58, 3 September 2007 (UTC)

The axle and wheel

I'm in an argument about the efficiency of rotational motion versus a piston stroke. The opposing argument is that since the piston stroke is well deployed in nature and nature has had longer to make changes to improve efficiency that it is more efficient than the axle and wheel. I disagree but before I sign off I want to find examples in nature of mechanisms used for locomotion, or what have you, that use rotational motion rather than back and forth oscillation to provide locomotion, pumping action or whatever. Clem 21:13, 3 September 2007 (UTC)

The flagella and F1Fo-ATP synthase. Aaadddaaammm 22:39, 3 September 2007 (UTC)

To expand on Adam's answer, we've got a good article with pictures and animations of ATP synthase in motion. TenOfAllTrades(talk) 01:01, 4 September 2007 (UTC)

It seems esier just to point out that there's no practicle way to have unlimited rotation in most natural curcumstances. If a single blood vessel attaches from the axle to the wheel, it will get twisted around the axle as the wheel spins, and either stop the locomotion or break. — Daniel 01:26, 4 September 2007 (UTC)

Don't forget tumbleweeds. StuRat 02:17, 4 September 2007 (UTC)

It didn't work very well for hedgehogs, who now prefer to run. And the hoop snake never got off the ground.--Shantavira|^{feed me} 08:22, 4 September 2007 (UTC)

Yeah, rotation is biologically very tough to provide. I remember it was quite a breakthrough when the mechanics behind the rotation of a bacterial flagellum was figured out. Gzuckier 15:27, 4 September 2007 (UTC)

Also note that that opposing argument isn't really an argument at all. While a human engineer seeks out the optimal solution to a given problem, evolution just throws everything at the wall and sees what sticks. There's no reason to think that it would have arrived at a particular design just because it's better in some respect; it just needs to be good enough to make it to the next round of play. --Sean 16:34, 4 September 2007 (UTC)

Right, there has to be an evolutionary path to it. Since a lumpy wheel is absolutely useless, you never get to a smooth, circular wheel. StuRat 17:32, 4 September 2007 (UTC)

Careful. How sure are you that a lumpy wheel is "absolutely useless"?

The arguments that "half a wing is absolutely useless" or "half an eye is absolutely useless" are frequently advanced as arguments against evolution. Yet as Richard Dawkins and others have persuasively argued, half a wing might be very useful if it allowed you to run faster or flutter a bit to escape a predator, and half an eye might be... well, "In the kingdom of the blind, the one-eyed man is king". And a half-good wheel might be just as differentially advantageous, until further selection managed to round it off more perfectly.

(But it's true, a wheel and axle does seem to be something biological systems have trouble with. Heck, even the T-1000 couldn't manage it.) —Steve Summit (talk) 01:57, 5 September 2007 (UTC)

A "lumpy wheel" is less useful than other, non-wheel, means of motion. A partial eye (say one that only senses "light" or "no light") can still be quite useful, and a partial wing would allow for short-range gliding, which is useful by itself. StuRat 06:31, 5 September 2007 (UTC)

You have to be really careful about this - evolution doesn't always (or perhaps ever) work in an obvious straight line from problem to solution. Whilst a 'lumpy wheel' might be useless for locomotion on land, it's possible that it might first evolve as a mechanism for propulsion through water - or to use as a means to 'flail' open shells or something. Once the thing evolves to that state, it can proceed to become a mechanism for propulsion. Think about how feathers first evolved as 'fluffy scales' to keep dinosaurs warm - then switched to being useful for flying - then for sexual displays (think peacocks) - then back to keeping birds warm (think penguins). Mechanisms don't have to evolve for their final purpose. SteveBaker 19:01, 5 September 2007 (UTC)

StuRat, you yourself pointed out a successful lumpy wheel: the tumbleweed. --Sean 19:29, 5 September 2007 (UTC)

Well, it's a wheel of sorts - but we're really talking about a "wheel and axle" per the OP - and we're stuck with flagellums as the only example in nature. SteveBaker 23:26, 5 September 2007 (UTC)

If this were article space and I were feeling snarky, I'd stick a "citation needed" tag after "A lumpy wheel is less useful than other, non-wheel, means of motion". I'm sure we could come up with plenty of non-wheel means of locomotion that a lumpy wheel is better than. (The inchworm, for starters, and quite possibly snakes, too.) --Steve Summit (talk) 23:55, 5 September 2007 (UTC)

Not to mention snails. --Anon, 22:34 UTC, September 6, 2007.

The way I'm reading some of the above answers is that examples of "wheels" already exist in nature, they're just very small. Friday (talk) 17:39, 4 September 2007 (UTC)

Yep - I think the few cases of bacterial flagellums are the only true examples of wheel/axle setups in nature. Those organisms are primitive enough that the flagellum itself doesn't need nutrients, a nerve connection or anything tricky like that. But in higher organisms, that stuff ends up being very hard to engineer - and evolution simply never got into that niche. SteveBaker 20:39, 4 September 2007 (UTC)

September 4

Atkins diet and neuroglycopenia

In a previous question, it was suggested by one editor that the reason the human brain is so loathe to burning fats in the place of sugar is the absence of fatty deposits around the brain and skull. But it has since occured to me that I don't recall hearing of mass cases of neuroglycopenia in Atkin's dieters. Does the brain begin processing fat from other regions of the body only after some time passes, relative to when other organs start? Are neuroglycopenia symptoms present early in starting the Atkin's diet? Or is the diet itself just high enough in carbs to avoid this? Could someone please dispel my confusion? Someguy1221 00:15, 4 September 2007 (UTC)

Your body can convert ingested proteins into glucose: see gluconeogenesis. As well, the brain can draw a substantial fraction of its energy from the ketone bodies, which are also produced from amino acids (protein components). TenOfAllTrades(talk) 00:59, 4 September 2007 (UTC)

Yes, but if the brain apparently lags behind the rest of the body in this regard, it logically seems it should present a problem at some point while starting on an Atkin's diet. Someguy1221 01:40, 4 September 2007 (UTC)

You perhaps misunderstood the previous response. The question was primarily concerning people feeling dizzy after vigirious exercise or perhaps if they haven't eaten when their body had been expecting food. Starvation or abnormal food sources are a completely different matter. Any glucose produced by the body can be used by the brain. Indeed it is done so, selectively. The problem is that gluconeogenesis is a fairly slow process (hours) so in the interim you may have a low blood sugar level which will particularly affect the brain as it can't use other sources when you have a low blood sugar level. Nil Einne 19:28, 6 September 2007 (UTC)

Normal adults can maintain an adequate blood sugar supply to the brain for over 3 days of starvation, even without use of fats for gluconeogenesis. Ketones represent additional fuel beginning after about a day of starvation. Dietary protein can be used for gluconeogenesis. A fourth compensation occurs as glucose transport into the central nervous system is enhanced to increase extraction from even borderline amounts of blood sugar. It is however possible that for an occasional person an Atkins diet may reveal a defect of blood sugar defense that would have gone unnoticed on a normal carbohydrate diet. alteripse 02:01, 4 September 2007 (UTC)

Ice and Hydrogen Bonding

First, a disclaimer from a RD regular: this is somewhat of a homework question, but I'm not looking for answers, just making sure I understand the material. I know ice floats in liquid water, and I'm told that this is because the hydrogen bonds keep the different atoms at 'arms' length" from each other (that's how my textbook puts it anyway). What I don't understand is that hydrogen bonds attract things toward each other, so why would the increase in hydrogen bonds make the molecules spread out and make ice less dense? My current understanding is that the increase in hydrogen bonds means that each individual molecule is being pulled from more "sides." Sort of like how having two friends pull on each arm will stretch you apart, not condense you together. Is this understanding correct? I've looked at the articles on hydrogen bonding and ice, but they don't quite get into the level of detail I'm looking for. Can someone more knowledgeable than me confirm or deny my understanding? --Ybbor^Talk 00:31, 4 September 2007 (UTC)

The water molecules are pulled by hydrogen bonding to get to the stable configuration of ice. But, like overexcited schoolchildren, hot molecules bounce, spin and vibrate too much to stay in any orderly formation, and those thermal forces are greater than the hydrogen bonding.Polypipe Wrangler 01:07, 4 September 2007 (UTC)

Ummm okay. I'm not sure that answers my question. To put it more simply: are the molecules being pulled further apart because more hydrogen bonds are acting on them, and pulling them in more directions? --Ybbor^Talk 01:09, 4 September 2007 (UTC)

No. In order for what you said to work, it would require an infinately large piece of ice. Ignore Polypipe; it looks like he's describing why ice melts. — Daniel 01:21, 4 September 2007 (UTC)

The hydrogen bonds are merely the reason why ice crystallizes in in a certain crystal structure which has a lower density than the unordered state. Cacycle 01:36, 4 September 2007 (UTC)

One way of looking at it is that, on average, each molecule in pure water can only form at most four hydrogen bonds: one from each of its two hydrogens, and two from the oxygen to hydrogens of other molecules. This means that, to minimize their energy, the molecules prefer to arrange themselves so that each one has only four neighbors. But if you take, say, balls of play-doh and try to arrange them in a lattice so that each one has four symmetrically spaced neighbors, you'll note that the resulting structure has lots of gaps: in a densely packed lattice each ball/molecule would have up to twelve neighbors. As ice melts, some of the hydrogen bonds break and bend, allowing the molecules to collapse into a denser, less orderly arrangement. —Ilmari Karonen (talk) 02:21, 4 September 2007 (UTC)

Imagine trying to pack strong bar magnets in a box. The magnetism keeps wanting to pull them into a single long string, which is not helping your trying to pack them into a nice tight rectangle. Same with H2O molecules; the peculiar shape with the hydrogens as little + bumps 90 degrees apart and therefore the - charge acting at the opposite end doesn't pack as well when the - and + line up nose to tail as when you can squoosh them together at whatever angle you like. Gzuckier 15:31, 4 September 2007 (UTC)

Roche limit

If a body be in an eliptic orbit that passes through the Roche limit of what it's orbiting, will it be torn apart while it's inside, but reform when it leaves? — Daniel 01:17, 4 September 2007 (UTC)

That depends on the fluidity of the body, the time it spends and the distance inside the Roche limit. For the vast majority of the cases, the answer is "no", but it is possible. The melting ice comet 73P/Schwassmann-Wachmann disintegrated without any tidal forces being responsible. ←Ben^B4 02:42, 4 September 2007 (UTC)

The friction during breakup will release heat, and thus energy, from the desintegrating body. And so my natural conclusion would be that it might not orbit out again. I'm not sure precisely what would happen, however. Someguy1221 02:50, 4 September 2007 (UTC)

As far as I can tell, that comet didn't reform, so I don't think it has much to do with it. Any estimate on how long an orbit like the one I'm suggesting could last? Do planets or satalites ever have that eccentric of orbits? — Daniel 03:04, 4 September 2007 (UTC)

Maybe this issue is precisely why planets and satelites don't have such eccentric orbits? Someguy1221 03:15, 4 September 2007 (UTC)

No, I think that's because planets formed about where they are, in roughly circular orbits, from the protoplanetary disk around the early Sun. They are also massive, so it requires a close pass by another major object to force them into highly eccentric orbits. This also has to do with why Pluto was excluded from the list of planets, as it seems to have a different origin. StuRat 12:09, 4 September 2007 (UTC)

Biking in the Rain

I commute on a bike to school every day, a few miles over rough sidewalk and across some heavily-traveled streets. If it rains, what should I do to keep myself and my books dry, and keep from getting hurt? (If this counts as "medical advice" or something similar, expert references would be just as good.) Black Carrot 02:33, 4 September 2007 (UTC)

mud guards on the wheels are especially helpful. It stops a muddy line being sparayed onto your back. Put your books into a waterproof bag. Wear a raincoat witha hood - bright yellow is good for visibility. But be aware that sound is blocked a bit from your ears, so it is harder to hear, and tell which direction the sound is coming from. Try to avoid riding in the dark as it's much harder to see in wet dark than dry dark. A bike rack on the back is good. Put something waterproof on the bottom and clip your bag on the top. How do you carry your books normally? Graeme Bartlett 02:55, 4 September 2007 (UTC)

It's best if the raincoat is a breathable fabric, (like GoreTex). I've seen some people using kayaking bags if it's particularly wet (they're waterproof and the opening folds over a couple of times to keep the rain out). Even if you use a waterproof bag, an extra plastic bag can't hurt. Use a flashing red rear light to make you more visible. And bring dry shoes and socks. Nothing you can do will stop your feet from getting soaked! Flyguy649 ^talk _contribs 04:20, 4 September 2007 (UTC)

Please check with your local law-enforcement agencies before attaching a flashing light to your bicycle, as it may be illegal. DuncanHill 18:19, 4 September 2007 (UTC)

One prob you might have is that it doesn't look like rain, so you don't wear rain gear, but it rains anyway. I suggest one of those compact plastic ponchos stuffed in your bag (which should be waterproof), for days when you guess wrong. StuRat 11:52, 4 September 2007 (UTC)

If you wear a helmet, pack a small towel at the bottom of your bag; doesn't take up much room and always nice to have dry hair / face afterwards. Nothing worse than trying to dry your face with those damn green paper towels. Lanfear's Bane —Preceding unsigned comment added by Lanfear's Bane (talk • contribs) 14:51, 4 September 2007 (UTC)

I modified my rainy day bike inspired by pictures of European commuting bikes. Besides mudguard/fenders, I stretched plastic sheet over the fender stays (the sort of coathanger wire things that hold the fenders on one end and attach to the bike frame or fork on the other) and the frame and fork to cover most of the sides of the wheel. It helped. Gzuckier 15:35, 4 September 2007 (UTC)

I did this for a few years, commuting several miles along heavily trafficked roads. I came up with a bunch of things that help. You can place your books in a plastic bag inside your backpack - surprisingly, the worst rain wetness always affected the bottoms of my books, not the top. Presumably this was from road splash. Avoid the obvious large puddles, they make you more wet. Wear a poncho, if you want, but it doesn't help a whole lot in heavy rain. I found that despite all of my efforts, I was always soaked through by the end of the bike ride, if the rain was heavy. In this case, I carried a pair of socks (several, actually) - because if only one part of me is dry, I prefer it to be my socks. Some people go all out and carry an entire change of clothes, but I never found that to be particularly helpful. Finally, you can use this opportunity to develop a philosophical outlook which anticipates catastrophic soaking, and adapts accordingly. This philosophy can be applied in all aspects of life, and creates a disaster-tolerant, resilient world-view. Nimur 15:54, 4 September 2007 (UTC)

never heard of a biking cape?--88.110.3.68 03:16, 5 September 2007 (UTC)

I usually carry my books in my backpack. And I wear sandals, so I won't need socks unless it gets a lot colder. So, I think the main points have been:

• Put my books in a waterproof bag attached to the bike
• Include emergency equipment and rain gear
• Get lights, and avoid the dark
• Wear a hooded jacket (preferably of an athletic material)
• Get things to cover my wheels so they don't splash

Looking good. What do I do about my pants? How will attaching a bag of books and stuff to my bike affect its handling? What should I do about my chain and gears? Does water effect my bike's braking ability, since the entire mechanism is rubber pushing on rubber really hard? Black Carrot 05:37, 5 September 2007 (UTC)

They do make rain gear that includes overpants. Alternatively you can just carry dry pants and underwear to change into. Overshoes or boots are also a good idea. The book bag shouldn't have much affect on handling as long as it's somewhat near the center of gravity of the bike, and a rack above the rear wheel is usually pretty good for this. A basket in front of the handlebars, on the other hand, is a really bad idea for heavy items. The chain and gears work fine while wet, but should be covered to limit spray. You will need to oil the chain and gears more often if the bike is used, or even left out, in the rain. The rubber brakes should work reasonably well in rain, and bike tires aren't particularly prone to sliding on wet pavement or hydroplaning, but caution (driving conservatively) is still a good idea. Puddles can be a problem in many ways, though:

1) Hitting a deep puddle at high speed will make a huge splash of muddy water that will drench you.

2) It's also like hitting the brakes, and you may fall forward if unprepared.

3) There can be hidden obstacles in the puddle, like nails or potholes.

Therefore, try to avoid going through puddles, or slow way down if you must go through them. StuRat 16:10, 5 September 2007 (UTC)

Also, big knobby mountain bike tires are likely to handle mud and water better than thin racing tires. StuRat 16:18, 5 September 2007 (UTC)

In addition, make sure the part of your water bottle that touches your mouth when you drink can't get muddy, or you could get a disease from drinking it. You might need to keep it in a plastic bag. StuRat 16:22, 5 September 2007 (UTC)

I commuted by bike for many years in Seattle, a city known for its rain. For the books, I suggest waterproof rear Panniers attached a back rack on your bike. A pair like these is what I use--look for a roll-down top (rather than a zipper or buckle), and all waterproof material (rather than waterproof fabric which fits over the bag for rain). As far as handling, for light-weights I hardly noticed the bags were there, and even the heaviest (sometimes 40-50 lbs, 18-23kg) was manageable. I would also recommend finding a rack which attaches to your frame rather than your seat post.

For clothing, I found it was best to shower and change cloths completely when arriving at work. That way I could ride hard through anything without worry. This may not be an option, but it is great if you can do it. Regardless, it is a good idea to waterproof (as water gets really cold when biking). What I found worked best was a thin waterproof (bright yellow) jacket over any insulating layers. If it was warm-ish, I wore ever popular spandex (Lycra) shorts; cold weather I had waterproof warm-up pants, again over something to keep warmer. If it were very cold (below freezing) I might wear a bandanna to cover my ears, but otherwise made no effort to cover my head with anything other than a helmet (with or without helmet cover).

Lights are a good idea, and may be legally required where you live. Check your brakes as well; They may take more work to stop in the rain (but tightening them and/or getting new brake pads goes a long way). Hope this helps. --TeaDrinker 20:34, 5 September 2007 (UTC)

As a car driver I can offer the following advice to minimise your risks (based on UK conditions)

• LIGHTS - I cannot stress this enough. Bright clean lights make it MUCH easier for us to see you in poor visibility.
• Reflective/Flourescent Clothing - Reflective clothing reflects our headlight light back at as, and flourescent glows in the dark - you can get combined garments.
• Wear light clothing - Don't wear black - we can't see it!
• Wear a helmet - this can save your life
• Keep your bike properly mantained - bald tyres or worn brake blocks will not help!
• Obey the rules of the road - Jumping red lights, cycling on the wrong side of the road or the wrong way up one-way streets are good ways to get into accidents.
• Be aware you are more difficult to see than a car - never assume a driver has seen you.
• Don't cycle up the inside of vehicles - they may change lanes or turn into you.

Exxolon 00:01, 6 September 2007 (UTC)

I've gotten a plastic jacket-and-pants set (for some reason, Wal-Mart had a wide selection and the local bike shop had none), and I'll get the rest as soon as I can. Thank you very much for your help. Black Carrot 17:46, 7 September 2007 (UTC)

needing to know what kind of spider i have found.????

i live in n.e. texas and was hunting the other day when i came across several spiders within about 2 acres. they all are black with white spots on them and around3/4 inch round and all had the same (crab shell back) on them. i have never seen these before and i cannot seem to find them on the internet. can someone please tell me what kind of a spider it was and also if it is dangerous or not.

thanks..masonstorm41102 —Preceding unsigned comment added by 4.90.32.54 (talk) 05:01, 4 September 2007 (UTC)

Can you post a pic ? StuRat 11:45, 4 September 2007 (UTC)

My first guess is a type of orb-weaver spider though. They're fairly common, and I know some have patterns like you mentioned, and fit the size you mentioned. Did it look something like this or this? --Wirbelwindヴィルヴェルヴィント (talk) 00:59, 5 September 2007 (UTC)

By "crab shell back", what do you mean? Do you mean it has spiny bits thrusting up along the edges? Does it look a bit like this [10]? If not, search on google for spiders of texas and see if you can find a picture of it. Black Carrot 05:41, 5 September 2007 (UTC)

I think you will find your answer here: http://entomology.uark.edu/museum/steatoda.html Looks pretty similiar to me. —Preceding unsigned comment added by 70.246.85.49 (talk) 20:43, 7 September 2007 (UTC)

Kinematics formula

How did the formula $v_{f}^{2}=v_{i}^{2}+2a(x_{f}-x_{i})$ come to be? How can you explain it in terms of integrals or visually using graphs? --antilived^{T | C | G} 05:17, 4 September 2007 (UTC)

To arrive at $\,x_{f}-x_{i}=v_{i}t+{\frac {1}{2}}at^{2}$ integrate acceleration with respect to time twice. x_i and v_i arise as the constants of integration. Further, knowing that uniform acceleration is defined as $a={\frac {v_{f}-v_{i}}{t}}$, and thus $t={\frac {v_{f}-v_{i}}{a}}$, this formula can be put in place of time in $\,x_{f}-x_{i}=v_{i}t+{\frac {1}{2}}at^{2}$. Simple algebra thereafter yields $v_{f}^{2}=v_{i}^{2}+2a(x_{f}-x_{i})$. Someguy1221 06:18, 4 September 2007 (UTC)

I understand $\,x_{f}-x_{i}=v_{i}t+{\frac {1}{2}}at^{2}$, but it's the steps after that to get that formula that I'm not quite sure of... --antilived^{T | C | G} 06:26, 4 September 2007 (UTC)

Well, once you substitute the new equation in for t, you get $x_{f}-x_{i}={\frac {v_{i}(v_{f}-v_{i})}{a}}+{\frac {1}{2}}a{\frac {(v_{f}-v_{i})^{2}}{a^{2}}}$, which (after multiplying each side by a) expands to $a(x_{f}-x_{i})=v_{i}v_{f}-v_{i}^{2}+{\frac {1}{2}}v_{f}^{2}-v_{i}v_{f}+{\frac {1}{2}}v_{i}^{2}$. This simplifies to $a(x_{f}-x_{i})={\frac {1}{2}}v_{f}^{2}-{\frac {1}{2}}v_{i}^{2}$. Hope that helps. Someguy1221 06:41, 4 September 2007 (UTC)

You could also note that the distance traveled is equal to the average velocity times the time taken: $x_{f}-x_{i}=\left({\frac {v_{i}+v_{f}}{2}}\right)\left({\frac {v_{f}-v_{i}}{a}}\right)$. Then multiply both sides by $2a$. -- BenRG 09:58, 4 September 2007 (UTC)

softwood shipping markings

can anyone help me I need a full list of wood shipping markings, the ones that are printed on each piece of wood with country , and the grades of wood.

Thank you

jasimps —Preceding unsigned comment added by 91.105.62.225 (talk) 06:11, 4 September 2007 (UTC)

Didn't you already ask this elsewhere ? StuRat 11:44, 4 September 2007 (UTC)

I think I saw it recently too, but I don't think it got much of an answer, which may be why it's been asked again (with seemingly the same response again. --jjron 07:09, 5 September 2007 (UTC)

Sutherland's constant

I need to know the parameters in the Sutherland equation to calculate the viscosity of methane. I've trawled the internet, and the textbooks I have, and can't find them anywhere. Does anyone know where I can get them? 84.12.252.210 08:15, 4 September 2007 (UTC)

• The book "Flow of fluids through valves, fittings, and pipe" should have the parameters, and a decent university library should have that book. --Sean 16:50, 4 September 2007 (UTC)

That's great, thanks. Hopefully I'll manage to get to a library fairly soon... 84.12.252.210 08:03, 5 September 2007 (UTC)

Charon ?

See [11].

Is Charon, the largest moon of Pluto, also visible in this discovery photo of Pluto ? I see a dim dot at approximately the 2:00 position from the left photo of Pluto (shown by the arrow). I don't see that dim dot on the right pic (either near Pluto's original or new location), possibly because Charon is in front or behind Pluto in that pic. I'd like to label the caption accordingly, if it is Charon. StuRat 12:29, 4 September 2007 (UTC)

I seriously doubt that is Charon. However, it is 19,570 km from Pluto. Pluto is 2,390 km wide. So, if you consider the "dot" of Pluto to be a "pixel". The "dot" of Charon would be 8 pixels away. That is about how far away that faint dot is. The reason I doubt it is Charon is because it took so long to discover Charon - so wouldn't they have noticed it right away if it was on the discovery photos? Of course, they may have simply overlooked it. -- kainaw™ 13:26, 4 September 2007 (UTC)

How does the brightness relative to Pluto fit with the pic ? Also, do we know if there is a star or other object in that location ? StuRat 13:39, 4 September 2007 (UTC)

I'm not sure how you can calculate how many pixels that Charon should be away from Pluto on the image without a scale being there. You can't just assume that Pluto is 1 pixel wide. After all, many stars in the image appear much wider than 1 pixel wide, but in terms of angular diameter, even the close-by stars are going to be around a few milliarcseconds across. That's approximately the same as, say, a person's thumb width viewed from something like 300 miles away - and that's for the close-by stars. The maximum distance from Pluto to Charon is less than an arcsecond. I can't identify which particular stars are in the image at the moment (but they're in Gemini, near to Wasat) - so can't tell the scale of the picture - but I highly doubt if the resolution is good enough to show two faint bodies as separate objects. Most ground-based telescopes need adaptive optics to split Pluto and Charon. Richard B 15:15, 4 September 2007 (UTC)

In a plate like that, you can't easily tell the relative brightnesses. Also, the bloom on the plate means that you can't tell size due to the size of the planetary disk from the bloom caused by the brightness of the object. Pluto would have been a LOT smaller than "one pixel" on that plate. So I don't buy [[User:Kainaw's "8 pixel" argument. Charon is also a lot dimmer than Pluto - it has half the diameter (ie 1/4th the area) and a 25% lower albedo - so it should be about ten times dimmer than Pluto - those two dots look to be about the same brightness to me. But when Clyde Tombaugh discovered Pluto in 1930, he was using a 'blink comparator'. If anything visible besides Pluto was moving within the frame, he'd have seen it immediately and Charon would have been discovered on the same day as Pluto because they'd both 'blink' together. When the moon was discovered in 1978, the did a search back through old photos of Pluto to see if a moon had been visible in earlier photos - and the oldest picture they could find that showed any sign of Charon was from 1965. That photo is described as showing a 'bulge' in the image of Pluto that comes and goes over time - the bulge was therefore determined to be Charon and the effect of it's orbit causing the bluge to come and go. This means that with the telescopic magnifications available even as late as 1965, Charon wasn't even visible as a separate dot. With the technology of the 1930's there is no way that a 10x dimmer object could have been visible on the plate! So, no - the image in that plate most certainly isn't Charon - and User:StuRat would be wrong in changing the caption. SteveBaker 15:27, 4 September 2007 (UTC)

I don't think you're looking at the right object if you say they are about the same brightness. If you continue past the dim object in the 2:00 direction you will see a brighter object that is constant in both pics. That's probably the one you are looking at. Try to make out the dimmer object between Pluto and that object in the left frame. Also, were huge improvements in optical telescopes made between 1930 and 1965 ? StuRat 17:12, 4 September 2007 (UTC)

That's definitely not Charon. Here are some of the discovery images for Charon; it was only visible as an elongation of Pluto in 1978 [12]. The January 23 plate is more exposed than the January 29 plate, so the dim star you're seeing probably just didn't come through in the second image. Those plates were taken with a 13-inch telescope on the ground. Here's what Pluto + 3 moons looked like from the 94-inch Hubble Space Telescope in 2006: Pluto system 2006. The 1978 images were from a 61-inch telescope. So there's no way that Tombaugh could have resolved Charon so well with a 13-inch telescope in 1930. But let's do the math. Pluto doesn't move very fast, so Tombaugh was observing the motion of Pluto because of parallax as the Earth moved. The parallax over six days, at opposition, would be about (2*pi) * (1 au / 30 au) * (6 days / 1 year) = 0.0034 radians = 0.2 degrees. The max elongation of Charon from Pluto is (20,000 km / 30 au) = 4.5×10^-6 radians = 0.00026 degrees, or 1/800 the distance that Pluto traveled from one plate to the other. From the image, I get that Pluto moved about 177 pixels, and your small dot is about 12 pixels from Pluto, a ratio of 1:15 instead of 1:800. So the real Charon is about 50× closer to Pluto than that small dot is. --Reuben 19:10, 4 September 2007 (UTC)

File:Analysis of Pluto discovery plates.png

This image is a crop of the result of overlaying the two images (red==righthand side, green=lefthandside). As you can see, they don't match up exactly. The dot pointed at by the green arrow is Pluto when the left photo was taken, the dot pointed at by the red arrow is where it was when the righthand photo was taken. Yellow areas are where nothing moved between the two photos - which (theoretically) would be everything except Pluto (and maybe, Charon)...except that they don't line up very well because the plates simply aren't that exactly registered - so everything on the left of the image has the red dot slightly to the left of the corresponding green dots - and everywhere on the right of the image, it's the other way around. In addition to Pluto, you can see (as StuRat claims) a faint green dot with no matching red dot off to the left of it - which I marked with a blue arrow. So - is this Charon? Well, there is no matching red-dot up by the red arrow - but I guess StuRat is going to claim that Charon moved either in front or behind Pluto. Sadly, that argument doesn't hold water. Charon's orbit takes 6 days, 9 hours - and those two photos were taken 6 days apart...so Charon ought to be in the same place (relative to Pluto) in both photos...and it's not. Sadly, the red image has a lot fewer stars in it than the green one you can see lots of green stars up above the green arrow for example so this putative 'Charon' is not the only example of a green dot that vanished in the red image. These could be due to clearer 'seeing' in the green image than in the red one - it's hard to tell. If you ramp up the gain on this image, you can actually see very faint red images of those stars - but you can't see even a trace of "Charon" to the top-left of the red arrow, no matter how much you boost the image. It's definitely not Charon. SteveBaker 19:35, 4 September 2007 (UTC)

Looks like some good evidence there, guys. Steve, could you show us that pic with the red cranked up ? I think I saw traces of most of the left plate's dim spots on the right plate, although right at the limit of perception. For the one I thought might be Charon, however, I saw no trace at all. As for it not being in front or behind on the right plate, it seems we only need to vary the orbital speed of Charon, the starting location, or the time between the plates (was it exactly 6 days or a few hours off ?) slightly to get that result (say 3/4 of an orbit). Charon being 1/50th as far away as it appears is more convincing, unless there is a major mistake in the figures. StuRat 20:33, 4 September 2007 (UTC)

Tombaugh's 1980 book (with Patrick Moore) Out of the Darkness includes a photo identified as "the best image" of Pluto then available, taken from a 155 cm plate. As enlarged for the book, the planet shows as a 6 cm wide disk -- but that's not its real diameter, just the telescope's circle of confusion. Charon is visible as a bulge causing one side of the disk to protrude an extra 1 cm.

The book doesn't mention what time of day the two discovery plates were taken. It does mention that the two images of Pluto were 3.5 mm apart, the size of the plates being 14x17 inches (356x432 mm). Each plate showed hundreds of thousands of stars. When blinking, Tombaugh systematically viewed one 10x20 mm area of the combined plates at a time until he had covered the entire plates. --Anonymous, 23:18 UTC, September 4, 2007.

Look: Firstly, Reuben's argument is pretty convincing there simply isn't enough angular resolution in those photos. Secondly, the historical record shows that even with 1965 technology, Charon didn't show a separate disk - and FOR SURE, the guys who first found Charon would have looked back at the original 1930's plates to see if it were there. If they didn't see Charon in them then we won't either. Thirdly (and, for me, most telling) we know that Tombaugh used a blink comparator on those two photos - which means that if Charon were really that visible it would have 'blinked' along with Pluto (because of the coincidence of there being 6 days between the photos and Charon's orbit being close to 6 days). So if Charon were visible in those plates, he would have discovered both moon and planet at the same time - and it took another 48 years of advances in telescope design for that to happen. Remember too that he was looking at the original plates so it would have been blindingly obvious if we could really see it in our scans of copies of those plates. So give it up. For sure that's not Charon - let's just end this pointless debate. SteveBaker 23:31, 4 September 2007 (UTC)

I've just managed to find the area in question. It's just over half a degree away from Wasat, and the spiral fuzzy thing in the top of the image is the galaxy NGC 2365. The brightest star in the image is around magnitude 8.5. Pluto moves just over 7 arcminutes during the 6 days. If the 177 pixels is accurate, then the scale of the image would mean that Charon would lie around 1/3 of a pixel away from Pluto at maximum separation, rather than the 12 pixels that the suspect image does. If you're still not convinced, then wikisky.org shows a star at that precise location: USNOA2 1050-05082251. It's at around 16th magnitude. See here Richard B 00:37, 5 September 2007 (UTC)

Nice work, Richard. I found Charon's absolute magnitude listed as 0.9, that can't be the same type of magnitude, can it ? I also found another mystery. The fairly bright object in the upper, left corner of that cropped image provided by Steve above only shows in the left plate, and doesn't show up at Wikisky, either, even though far dimmer stars do show up there. StuRat 05:56, 5 September 2007 (UTC)

I don't know what it is, but I would have thought (but can't check until later this evening at least) that it's probably just an asteroid - particularly as it's close to the ecliptic. If it's a main belt asteroid, then its movement could usually be detected on photographs after only a few minutes, and the angular distance that Pluto appeared to move over those 6 days could be completed in a few hours - so you would expect that the asteroid wouldn't appear on the 2nd plate 6 days later.Richard B 11:28, 5 September 2007 (UTC)

<edit>Commenting on the brightness of the object, the USNO catalogue magnitude is 16.2 for that star, the absolute magnitude of Pluto is around -1.0, and of Charon 0.9, but at around 42 or so AU from the Sun, the apparent magnitude of Pluto was about 15.1, and Charon around 17.0. Mag 17.0 is around twice as faint as mag 16.2. Richard B 13:22, 5 September 2007 (UTC)

Thanks (so I wasn't all that far off as far as the brightness goes). StuRat 15:24, 5 September 2007 (UTC)

Hi Steve, I don't think our anonymous friend was arguing that the dot was Charon. He's just providing some supplementary information of interest. --Reuben 01:59, 5 September 2007 (UTC)

Yes - I know - I was replying to the previous message from StuRat. There was something of an edit conflict. I fixed my indent level to try to make that clearer. SteveBaker 02:47, 5 September 2007 (UTC)

Thanks, Reuben. I should perhaps have said explicitly that if the best image available in 1980 didn't come close to showing Charon as a separate dot, then obviously that a 1930 image from a smaller telescope would not. The other information was indeed intended just for interest. --Anon, 03:23 UTC, September 5.

I'm not arguing either, I just wanted to see if I was right in saying that there is no trace of that dot in the right plate, while there are traces of other dots, which appear just as dim in the left plate. I accept most of the arguments given and no longer suspect that dot of being Charon. Thanks for your help, everyone ! StuRat 05:40, 5 September 2007 (UTC)

Psychologist >>> Physician

Can a Psychologist become a Physician? (in the UK or US) Or should he/she study the whole career of medicine from the beginning? —Preceding unsigned comment added by 85.57.21.17 (talk) 17:25, 4 September 2007 (UTC)

Our article Medical school in the United Kingdom may help, however it would be advisable to contact medical shools directly to ask, as their response would depend on the precise nature of the existing qualifications. Generally, however, there are very few "graduate entry" places for medical training in the UK, and the great majority of doctors (we rarely call them physicians) will have undertaken the complete undergraduate route. I have no knowledge of the system in the USA. DuncanHill 18:07, 4 September 2007 (UTC)

I would guess anyone would have to go to the beginning of medical school to become a doctor. It's different from the UK as the above poster puts it about the "undergraduate route". In the US anyone can major in anything as an undergrad to get into med school, provided that you took the classes that the schools look for.128.163.224.222 20:13, 4 September 2007 (UTC)

There are doubtless a few graduate psychologists (in the U.S. you should have at least a Masters degree to call yourself a psychologist) who took scientific courses in their undergrad careers rather than liberal arts or psychology. Someone, for instance, who passed a premed program as an undergrad, could have then, for whatever reason, pursued a grad degree in psychology, then had second thoughts and applied to med school, and been able to go on in his education and finish the medical degree. If he had not taken the rigorous science courses in premed, he might have to take two years or more of refresher or catchup courses before being able to gain admission to med school. Some med schools have a more lax admission policy than others. Hardly any undergrad or grad courses in psychology would substitute directly for med courses. All that said, yes, a psychologist can become a physician, as can anyone else, if they are smart, willing to work hard, and have many years and hundreds of thousands of dollars to devote to the effort. Edison 03:28, 5 September 2007 (UTC)

You probably would want to read up on the differences between Psychologists versus Psychiatrists. You can get a PhD in psychology or you can go to med school and do a Psychiatry residency and fellowship. If you are already a psychologist, you would have to apply to med school to become an MD.
Mrdeath5493 03:55, 6 September 2007 (UTC)

Frequency

Does two-hourly mean every 2 hours or every half an hour? (Not talking about ound or anything like that). 20:59, 4 September 2007 (UTC)

I would actually say that it is ambiguous. The prefix "bi" (which most literally means "two") for instance, can mean "every two" or "twice every." Someguy1221 21:05, 4 September 2007 (UTC)

TO mean it would be every two hours, as opposed to half hourly. But what did the author mean? Graeme Bartlett 21:40, 4 September 2007 (UTC)

I've rarely if ever seen e.g. "bimonthly" to mean anything other than every two months. —Tamfang 01:51, 5 September 2007 (UTC)

I think this post belongs on the language ref desk - it's hardly a matter of science. SteveBaker 22:07, 4 September 2007 (UTC)

It could be a matter of life-and-death if we're talking about dosages!! Wikipedia cannot give medical advise! If this is indeed a dose question, please contact a doctor! --Mdwyer 00:53, 5 September 2007 (UTC)

Actually although this will depend on where you live a pharmacist may be a better choice although both should either be able to answer your question or direct you to the person who can Nil Einne 15:03, 7 September 2007 (UTC)

Since hourly means every hour, I would take two-hourly to mean every two-hour, er, two hours. It's not a common usage. The other would be twice hourly. —Tamfang 01:51, 5 September 2007 (UTC)

I'd suggest the answer is in the hyphen. "Two-hourly" would suggest every two hours; "two hourly" would suggest two per hour. It may be nice to have some more context though. --jjron 07:06, 5 September 2007 (UTC)

Train service and [13] 22:37, 5 September 2007 (UTC)

I'm pretty sure it means once every two hours, but it'd be easiest to look at a schedule if you can get one. Black Carrot 17:53, 7 September 2007 (UTC)

meaning of convected in vortex dynamics

If an experiment claims that a vortex convects a pressure difference of 0.4.05 atmospheres downstream, is this the amount of pressure it looses along the way or how much it delivers upon impact. Thanks for your time Robin —Preceding unsigned comment added by 80.6.35.136 (talk) 21:51, 4 September 2007 (UTC)

I'm not sure I really understand the situation (0.4.05 atm?), but given the use of the term 'pressure difference' I would take an educated guess that you're looking at differences, and therefore how much pressure it looses. --jjron 07:01, 5 September 2007 (UTC)

Weather Systems?

I realize that this question in general, is incredibly broad, but where do weather systems originate?

What causes the changes in atmospheric pressure? Where do cold and hot fronts start? Is there a factor that causes these weather factors to change?

Thanks in advance,

Perfect Proposal ^{Speak out loud!} 23:10, 4 September 2007 (UTC)

Well, the sun shines on ocean water, ice, grasslands, desert, forest, etc. Each of those reflects sunlight back to a different degree and absorbs the rest. Hence (for example) desert sand gets really hot in the sunshine - but the nearby grasslands (say) do not. The air above the desert gets some of that heat and expands - the air over the grassland stays cool and does not expand. Now, the density of the air over the desert is less than that over the grass - so "hot air rises" - so the hot air goes up and is replaced by cool air from the nearby grasslands. Now you have a wind blowing from the cooler area to the hotter area. If the heat is over water, then some of the water will evaporate - cooling the ocean (and hence the air) and putting water vapor up there. The water vapor forms clouds - which being white, reflect the suns heat back out into space - further cooling the oceans beneath. Multiply all of these increasingly complicated effects by the size of an entire planet - and you get winds and clouds and all sorts of other complicated effects. Air doesn't move simply - it make swirls and vortices as it passes over mountains or as a cool 'wall' of air hits a warmer wall coming the other way.

Air pressure varies because (as I said before) warm air is lighter than cool air - so when warm air from a nearby desert (or whatever) blows past your home - the air pressure drops. When cool air from the snowy north blows your way, it's denser - heavier - and therefore (in general) exerts a higher pressure. 'Fronts' are places where the air temperature changes suddenly - as at the boundary between grassland and desert - or ocean and forest - or whatever. They move because of the 'hot air rises and cold air flows beneath it' - but because this is an insanely complicated system of whorls and vortices on a planet-wide scale, it's never that simple. Fronts are important because if a mass of warm, wet air is pushed upwards and cools off abruptly, it cannot hold as much water vapor - so it comes down as rain or snow. If that upwelling of air causes sufficiently violent turbulance then clouds can get charges of static electricity and you'll have lightning - or little vortices can be spun off causing tornadoes. It's all to do with the motion of the air - the transport of heat and water vapor.

The factors that cause the weather to change are the more or less random ones caused by all of this complex 'chaotic' (in the mathematical sense) motion - and of course things like the day/night cycle (everything cools off at night and heats up during the day - so again, air changes density and winds blow) - the seasons...everything affects everything else. So the weather changes - and on a small scale, it's very random indeed. Nobody can predict whether there will be a gust of wind where you are right now at 2:43pm tomorrow. On a medium scale, it can be predicted (Will it rain tomorrow? We can make a pretty good guess.) - and on a very large scale, it's completely predictable. (Will it be hotter in summer in Texas than in winter? Will it snow in Alaska this year?)

SteveBaker 00:35, 5 September 2007 (UTC)

Just a nitpick, but air doesn't "hold" a different amount of water vapour at different temperatures; gasses operate independently from one another. As the temperature drops in a given area, there will be a net increase in condensation, resulting in cloud formation. Matt Deres 16:25, 10 September 2007 (UTC)

September 5

measuring mass

Since G is known to only 4 digits (if memory serves), the mass of any planet is known to 4 digits at most. But how many digits of GM are known for Earth? For other bodies? —Tamfang 01:59, 5 September 2007 (UTC)

Interesting question. According to this, it's a ppb for the Earth, from satellite ranging data: [14]. --Reuben 02:20, 5 September 2007 (UTC)

Yeah - that is indeed an interesting question. Our Earth article quotes the mass of the earth to 5 digits - Gravitational constant quotes G to about 5 digits too - which is to be expected if we only measure the mass using gravitational experiments. There are (in principle) other ways to measure mass than through gravitation though. We were discussing the problem of measuring the moment of rotational inertia of the moon just a few days ago. That would provide an independent measure of mass that would not depend on G - but rotational inertia is a tricky thing to measure without knowing the density gradient of the body. Evidently it didn't get us anywhere in terms of a more accurate mass number. If we knew the mass of the earth (or the moon or whatever) to more precision than G - then we'd only have to measure the accelleration due to gravity ('g') to enough precision and we'd know G to more precision too. We can surely measure g to insane precision (our article Standard gravity suggests that it's been measured to at least 7 digits at sea level) and I know for sure that the radius of the earth at mean sea level at 45 latitude is known to at least 7 digits - so the precision of GM for the earth ought to be around 7 digits too - but without some other precise measure for the mass (such as using rotational inertia or something) the precision of the mass of the planet and the precision of G are intimately linked. SteveBaker 04:27, 5 September 2007 (UTC)

Science Project

I'm working on a 3d model of a plant cell. I need help finding what non-edible object I can use to represent cytoplasm, golgi body, and chloplast. Any ideas? Ex. ribsomes-small fuxxy balls —Preceding unsigned comment added by 216.78.224.53 (talk) 02:04, 5 September 2007 (UTC)

On my son's plant cell model (yes, everyone gets to make one of these!) he used some 1" wide pink ribbon (stuck together with hot-glue) for the Golgi body, he put a sheet of clear overhead-projector plastic through a shredder to make long transparent strips which he crumpled up to fill up the cell as cytoplasm (you can see it's there - if you use some imagination, it looks kinda liquidy - yet you can see through it to see the other 'stuff' inside the cell) and for the golgi body we used one of those green 'Jif' limejuice containers that looks like an actual lime fruit because it's kinda round with pointy ends (you're out of luck if you don't live in the UK - I've never seen them sold anyplace else). We also used various coloured beads to represent Peroxisomes and the various vesicles. The ubiquitous pipe cleaners (which are NEVER used for cleaning pipes - but are a requirement for every single school project) were coiled up to form mitochondria and left uncurled for the cytoskeletal filaments. The nucleus was a foam ball with curled strips of paper for the endoplasmic reticulum. The cell wall was made from two clear plastic bubble containers clipped back to back with paperclips so it could be undone for the purposes of exhibition. The plasmodesmata were painted on the outside. I miss school projects - that panic 3 hours before bedtime on a Sunday night when my kid would reliably remember that the project that he'd known about for the past three weeks was due Monday. The scouring of the house for things that could *somehow* be made into a scale model of Mount Rushmore or a DNA molecule. (I once helped him build a 6' tall 2' wide DNA molecule using string, UPVC pipe, a couple of 2x4's and the entire contents of his long disused garden ball pit in under 3 hours! It turned out to be quite a structural engineering problem to keep the twist in it without the whole thing sagging - hence the 2x4's! The teacher was keen to point out that he'd said that it had to be over six INCHES tall - but four years later, and the giant DNA molecule still adorns the classroom...I guess they havn't figured out how to get it out to the dumpster yet!) SteveBaker 02:42, 5 September 2007 (UTC)

What is this creepy crawler?

I was just wondering if anyone knew what species this little creature is called. It's very fast moving because of the many legs so I was not able to catch it and toss it out the door. If it helps; the location is upstate New York.

Picture --MF14 02:07, 5 September 2007 (UTC)

Could be the House Centipede128.163.116.67 02:11, 5 September 2007 (UTC)

Oh, jeez. Now I'm more creeped out after reading that article. Thanks for the help though. --MF14 03:51, 5 September 2007 (UTC)

Could be worse ---->

--Sean 13:22, 5 September 2007 (UTC)

Remember, we look just as ugly to him. Edison 13:30, 5 September 2007 (UTC)

Yeah, when I visited the Asian tropics, I came across a few of these critters. Not many animals are "icky" to me as the tropical centipedes. I don't mind looking at a picture, but the motion that they have, and the distinct color, are disturbing. For some of them, if you touch them, will stop and coil.128.163.160.128 19:14, 5 September 2007 (UTC)

Hey, speak for yourself! ;-) --24.147.86.187 14:12, 5 September 2007 (UTC)

Anyway, yeah, house centipedes. Ugly and freaky fast. Blink and you'll miss 'em. And they can get quite large. If you hit them with something (say, a shoe), they disintegrate into a mess of flimsy legs. Ugh. Something about their ridiculous number of legs and their practically unbelievable speed (for something that size, and as an insect) makes them exceptionally creepy. Bleh. --24.147.86.187 14:24, 5 September 2007 (UTC)

Yea, when I see one and get something to squish it with, it is usually gone by the time I'm ready, leaving me wanting to burn the house down and rebuild. StuRat 15:13, 5 September 2007 (UTC)

Just a minor quibble: centipedes are not insects. They belong to the subphylum Myriapoda that includes millipedes as well as centipedes. Although they are--like insects--arthropods, the mulitple segments and legs distinguish them from insects with their three body parts and six legs.--Eriastrum 16:45, 5 September 2007 (UTC)

Good information; thanks! --Sean 17:56, 5 September 2007 (UTC)

There's something elegant and fearsome about tropical centipedes; although they're frightening, they look cool in a Boba Fett sort of way. House centipedes are just disgusting. And are they really that poisonous? Should I, for instance, tell my cat to stop eating them?--The Fat Man Who Never Came Back 20:24, 8 September 2007 (UTC)

Its a good thing to have around actually since it is an insectivore. It will hunt and kill other insects in your home which would be bad to have. So don't kill it. Remember that it is probably killing hundreds of spiders, ants, roaches, and countless other creepy crawlies. So one creepy crawly is better then hundreds.

Heat exchangers

Why does the resistance to heat transfer (1/U) in a plate heat exchanger (with hot and cold water) decrease as the mass flow rates of each of the fluids is increased?

202.180.90.123 02:52, 5 September 2007 (UTC)

To get a start on this (homework) problem, look at the equations for conduction resistance (in the heat exchanger) and forced convection resistance in each of the fluids. A diagram showing how the resistances relate, in series or parallel, may help. anonymous6494 03:32, 5 September 2007 (UTC)

what is the capital of singapore?

--166.121.36.232 06:56, 5 September 2007 (UTC)

Singapore is one of the few remaining city-states. As such, the only city, Singapore, is both the capital and the name of the nation. StuRat 07:02, 5 September 2007 (UTC)

As a city-state, the capital is known as Singapore City. Rockpocket 07:04, 5 September 2007 (UTC)

I believe it's called Singapore City only when the need arises to distinguish that you are talking about the city specifically, much as New York is only called New York City when the need arises to distinguish it from the state. StuRat 07:11, 5 September 2007 (UTC)

Umm, not to be picky, but this is the Science Desk isn't it? I had to do a double check. Is this a Science Question? Anyway, it's got an answer... --jjron 07:15, 5 September 2007 (UTC)

I guess this is the closest thing we have to a Geography desk. Lots of geography questions get asked here, so....--Shantavira|^{feed me} 08:49, 5 September 2007 (UTC)

We have a Humanities Desk which would probably be the best place for this question. Geography is one of the Humanities, but it can also be a science.DuncanHill 09:01, 5 September 2007 (UTC)

It can be quite scientific, see color. :p Capuchin 09:35, 5 September 2007 (UTC)

Okay, here's a Science question, then: how come it gets harder to read small print as you get older? —Steve Summit (talk) 13:03, 5 September 2007 (UTC)

Presbyopia --LarryMac | Talk 13:26, 5 September 2007 (UTC)

That might look like a science question, but it's actually a social thing too: the so called "web designers" these days think that the more text they can fit on your screen, the better. – b_jonas 14:10, 5 September 2007 (UTC)

Why are you whispering? Do you think we can't hear you?87.102.5.137 14:26, 5 September 2007 (UTC)

THIS IS A SCIENTIFIC EXPERIMENT TO SEE WHETHER IT'S POSSIBLE TO SHOUT AND WHISPER AT THE SAME TIME! SteveBaker 18:52, 5 September 2007 (UTC)

<BLINK>What was the result? :-)</BLINK> --Anon, 22:28 UTC, September 5.

It was deafeningly quiet - I'm not doing it again, my ears hurt. SteveBaker 23:22, 5 September 2007 (UTC)

I actually did hear it in my head as a shouted whisper, or stage whisper. It was most disconcerting, and happens every time I look at it. It reminds me of reading Gulliver's Travels and finding the capitalisation and italisization (?) made me add weird emphases. Skittle 23:19, 6 September 2007 (UTC)

Genetics

My father was born with brown hair and blue eyes, my mother was born with blonde hair and green eyes, I was born with brown hair and blue eyes, if I have children with a person with blonde hair and green eyes, is there a good chance that my children would be blonde haired and green eyed too? --124.254.77.148 07:13, 5 September 2007 (UTC)

The genetics of even fairly simple things like eye and hair colour is not as simple as your standard textbooks make out. In very simple terms brown hair tends to dominate blonde hair, so your children would more likely have the darker hair. Similarly darker eyes tend to dominate lighter ones, as for blue and green I'm not sure. So I guess the simple answer is that your kids could have blonde hair and green eyes, they're probably more likely to have something else, but basically we can't predict for sure. --jjron 07:19, 5 September 2007 (UTC)

If you want to pretend this is one of those simple text book examples, it will be 50/50. A more full pedigre of your family might offer a better picture. Someguy1221 08:13, 5 September 2007 (UTC)

To summarize without going into arcane detail: Each of your children has an even chance of blond vs brown hair. We don't know whether your hypothetical mate has two green eye genes or green+blue, though the latter is more likely; in ignorance, each child has at least an even chance of green eyes (vs blue). —Tamfang 17:21, 5 September 2007 (UTC)

Exlpoding Paste

I know that exloding paste is made using ammonia and iodine crystals, but i don't know how much of each or what concentrations to use to get more controllable blasts. Anyone have any ideas?

Nebuchandezzar 09:40, 5 September 2007 (UTC)

Here [15] are instructions. The link is provided for information only - home experimentation with explosives is highly dangerous, ill-advised, and may be illegal in some jurisdictions. DuncanHill 10:43, 5 September 2007 (UTC)

Nitrogen triiodide is too unstable to get controlable blasts.87.102.5.137 10:45, 5 September 2007 (UTC)

"it is usually detonated by touching it with a feather but even the slightest air current or other movement can cause detonation. Nitrogen triiodide is also notable for being the only known explosive that detonates when exposed to alpha particles"

IF YOU TRY TO MAKE LARGE AMOUNTS IT'S QUITE LIKELY THAT YOU WILL BLOW YOUR OWN FACE OR HANDS OFF !!!

So don't try - it's not controllable87.102.5.137 10:48, 5 September 2007 (UTC)

Please do not experiment with this. It is far too unstable and unpredictable. I got little glass fragments in my hand many years ago from it going off, and some of them are still there. Fortunately my hand was between it and my face, otherwise I likely would have been blinded. "Large amounts" are anything more than more than a tiny speck. Edison 13:28, 5 September 2007 (UTC)

Luckily, iodine is not cheap. – b_jonas 14:44, 5 September 2007 (UTC)

How hot is it?

We have furnaces at work that heat the product up to ~2200° F. I'd like to know what this can be compared to. What other things, that are more common to the average person, come close to this temperature? I don't suppose we have a list of elements according to melting point or anything like that here... Or do we? Dismas|^(talk) 10:59, 5 September 2007 (UTC)

This page gives the melting point of glass as 1400 to 1500 kelvin, and by google's calculation, 2200°F is 1477K. Glass says that it's melting point is "around 1000°C", so that's 1300K, which is probably close enough for your use and might be something people can compare to? "Hotter than the melting point of glass." Capuchin 11:16, 5 September 2007 (UTC)

Note 2200F = 1 204.44444 Celcius (from google calculator) http://www.google.com/search?q=2200+F+in+centigrade&btnG=Google+Search

Melting points of the elements (data page)

List_of_elements_by_melting_point - better for your purposes?87.102.5.137 11:25, 5 September 2007 (UTC)

So you should be able to melt copper, uranium (as well as silver,zinc,gold easily) but possibly not manganese87.102.5.137 11:29, 5 September 2007 (UTC)

Interesting! Thanks! Dismas|^(talk) 11:41, 5 September 2007 (UTC)

May we ask what you need such a splendid furnace for? DuncanHill 13:24, 5 September 2007 (UTC)

Such a splendid furnace might be used for materials research, such as annealing, or in electronics and semiconductor dopant control (though this is pretty hot for silicon fab!). Nimur 14:29, 5 September 2007 (UTC)

Or making pots or casting Golden calfs?87.102.5.137 —Preceding unsigned comment added by 87.102.5.137 (talk) 14:47, 5 September 2007 (UTC)

Actually, it is for silicon semiconductor fabrication. I handle a little over US$4 million worth of product in a single day, based on the average value of each wafer. Dismas|^(talk) 20:20, 6 September 2007 (UTC)

How is the latest Opteron stepping doing? Nil Einne 14:56, 7 September 2007 (UTC)

We have great articles giving examples to things like this: see Orders of magnitude (temperature). Any power of ten with a unit like 1000 K also brings you to such a page. You have to convert 2200 °F to K first: it's 1500 K. – b_jonas 13:51, 5 September 2007 (UTC)

Headphones - left and right?

I've read the articles on both stereophonic sound, and headphones. I don't think either one tells me exactly the point of having 'left' and 'right', although I understand the point of having two channels recorded from different points of perspective. My question, does it make any difference to me whether I have the earpiece designated left in my left ear, and right in my right ear? Would there be a difference in sound if I switch them? Is there something 'wrong' in theory in terms of my appreciation of the music, if I have 'L' in my right ear and 'R' in my left? (The Ls and Rs are wearing off, and they are so small, I can't always read them w/out my glasses...) Thanks if you can help. —Preceding unsigned comment added by 213.84.41.211 (talk) 13:03, 5 September 2007 (UTC)

With the headphones reversed, the stereo image would be reversed, that is to say that sounds which should be on the left would now be on the right, and vice versa. DuncanHill 13:19, 5 September 2007 (UTC)

You won't particularly notice any difference with music, however, watching a movie or playing a video game with the headphones the wrong way around will make a large difference, as the direction that sounds are coming from will be switched which can be disorienting and completely ruin the experience. With music, you're not listening to the music the way that the artist intended it (if they paid enough attention to left and right). I also find with earphones that some are moulded to fit better in the ear if you put them in the correct ears. It's not going to make much difference with plain music at all, really. Capuchin 13:22, 5 September 2007 (UTC)

More likely, you're not listening to the music the way the producer or sound technician intended it ^^ --lucid 14:06, 5 September 2007 (UTC)

I had considered making that clarification, but i'm non-productively lazy, in the sense that now I had to write this to explain myself, rather than bothering to alter it when I was initially writing. Capuchin 14:14, 5 September 2007 (UTC)

It might be a neat psychology experiment to determine if there are aesthetic or perception effects due to reversing the stereo on an otherwise un-oriented sound source. Clearly, if you are watching a movie, the visual cues will not line up - but what if there is no video feed? Will it really make absolutely no difference to the experience if the sounds are reversed? Maybe it's more enjoyable (in the statistical aggregate) to have the guitarist to the right and the bassist to the left. Nimur 14:33, 5 September 2007 (UTC)

I suppose, theoretically, there could be a right brain/left brain issue where certain sounds are more pleasing to the left ear and others to the right ear, but I don't know of any studies on this, and the music producers probably don't either. So, if they more or less randomly choose which instruments go on which sides, reversing them is just as likely to improve the music experience as it is to degrade it. StuRat 14:57, 5 September 2007 (UTC)

Generally, it doesn't matter - you just flipped the positions of the instruments and mirrored the shape of the space they were recorded in - who cares? There are cases when it matters though - when watching movies or computer games obviously someone off to the right side of the screen fires a gun - you don't want to be given the impression that they were off to your left. But even without visual cues, there are recording techniques in which microphones are placed inside the ears of a 'human analog' - a plastic model head, with realistic ears - and filled with the fluids of the correct density to simulate skull and brain, etc. These are sometimes called 'Binaural recordings' to distinguish them from normal stereophonics - and sometimes they actually use a real human head to do the recordings [16]! When you record like that, you can actually reproduce a fully three dimensional experience in which you can tell the difference between sounds coming from in front and behind, above and below as well as left and right. The human brain figures out the full spatial positioning of sounds using just two ears by recognising subtle cues to do with how the sound bounces off your skull and refracts through your brain matter! Those effects are eliminated when the sound is piped directly into your ears - and binaural recordings add that information back in from the human analog head. It's not perfect because no two people have identical heads - but it's pretty damned amazing when you hear it demonstrated. Obviously, if you wear your headphones 'backwards', you'll destroy that effect - and possibly produce disorienting weirdnesses - it doesn't simply swap back and front, left and right - it actually screws up your audio positioning senses much as if you were in a really echoey cave or something. If you go to Binaural recording you'll see that we have a sample recording that shows this 3D sound effect (you have to be wearing headphones to hear it though). However, not much stuff is recorded that way because it doesn't sound right when heard on stereo loudspeakers. There are also ways to produce similar results by processing five channel audio down to 'spatialised' or '3D' stereo using fancy computer simulations of the effect of sounds bouncing around in a typical human skull, etc - and this is done in some computer games and in high-end PC sound cards. SteveBaker 15:33, 5 September 2007 (UTC)

One occasionally hears that when you try to remember an event you look up to the left, and when you invent a lie you look up to the right (or is it the other way round?). That suggests asymmetries in perception that *could* make a difference in music appreciation. —Tamfang 17:09, 5 September 2007 (UTC)

The film Bad Boy Bubby features binaural recording. DuncanHill 00:18, 6 September 2007 (UTC)

For those of use that have enjoyed classical music for years, it could be a bit disconcerting to hear the violins coming from the left. (note: after typing that line, I reread it, and thought that I should add "no pun intended" after "disconcerting", but thought better of it) Bunthorne 04:58, 6 September 2007 (UTC)

I was about to add a comment about orchestras but you beat me to it. However... aren't violins on the left, at least for people in the audience? Pfly 07:37, 6 September 2007 (UTC)

Quite right. I blew that one. Thanks for the correction. Bunthorne 08:17, 6 September 2007 (UTC)

Hmmm - so if you are a concert musician - used to hearing the music from up on stage, you should wear your headphones backwards when you listen to concert music!?  :-) 13:11, 6 September 2007 (UTC) —Preceding unsigned comment added by SteveBaker (talk • contribs)

How flaps reduse noise

I know that flaps help increase flying time although not thoroughly but it really tough to figure out how flaps reduse noise. I am an 1st year Aeronautical engg. student and i know the base of the subject.Please answer in a detailed manner.THANK YOU —Preceding unsigned comment added by Mansnipermanoj2007 (talk • contribs) 13:49, 5 September 2007 (UTC)

I would speculate that they reduce noise by reducing turbulence, but will let an expert give a more detailed answer. StuRat 14:45, 5 September 2007 (UTC)

You are referring to flaps on aircraft wings - right? Well, when you lower the flaps you increase both lift and drag dramatically. On take-off this permits the aircraft to gain altitude much more quickly - but requiring more engine power to overcome the extra drag. This actually makes the plane noisier because the engines are on a higher throttle setting - but it als reduces the noise 'footprint' (the places where the plane can be heard from on the ground) because the aircraft gets up and out of the way sooner. In effect, a steeper climb-out concentrates the noise to a region close to the airport - reducing noise further away. Around large commercial airfields, the climb-out rate is sometimes regulated in order to keep the noise levels within acceptable levels for communities right next to the airport - or to get the aircraft up to sufficient altitude to avoid inflicting noise on communities further away. On landing, the engines are generally throttled back until the very end so the noise levels aren't so critical - I suppose the extra drag from the flaps help reduce the need for the super-noisy thrust reversers but that's a minimal kind of thing. SteveBaker 14:52, 5 September 2007 (UTC)

Jet planes almost always takeoff at maximum engine power (unless it's derating its engine to extend its life and lower maintenance, then it will go at maximum allowable power), flaps just sacrifices some acceleration for lower takeoff speed, and the overall effect is faster climbing which means it can get away from houses quicker and thus less noise for the grounds people. --antilived^{T | C | G} 03:33, 6 September 2007 (UTC)

physiology fluid balance

why have mens bodys got a larger average % water content compaired to women —Preceding unsigned comment added by 84.71.58.156 (talk) 13:55, 5 September 2007 (UTC)

Possibly because women have a larger average % fat content, which helps during pregnancy and lactation, when extra energy is needed for the baby. This leaves room for a lower percentage of everything else, including water. StuRat 14:42, 5 September 2007 (UTC)

We've had several questions on the Reference Desk in the past that focused on the subject of "what percentage of a human is made of water." I think the consensus is that it's sort of a vague usage - i.e. which water should be counted? Pure water? Water in cells mixed with organelles? Chemically attached water? Thus, the constituency is difficult to define. I haven't heard this detail about a gender-related water constitution, but I would guess it's actually females with more water (I think I remember from biology that they have more adipose tissue, which holds water well). In any case, it's an ill-defined problem. —Preceding unsigned comment added by Nimur (talk • contribs) 14:43, 5 September 2007 (UTC)

Off the top of my head, I would assume men have a larger % water. Although adipose tissue does contain water, the cardiovascular system contains a lot more. Males have more muscle. Muscle needs more blood flow than fat. And the fact that there are more vessels means there has to be a greater volume of total blood to maintain blood pressure. So, males need more blood to fill their more numerous and larger vessels and thus contain more water.
Mrdeath5493 04:42, 6 September 2007 (UTC)

Deviation from relativistic mass for high energy particles

I understand that the 'mass' of accelerated nuclear particles deviates from the prediction of special relativity for higher kinetic energies. Can I get a plot of predicted and experimental results for this? What are the theories about this effect? 69.150.27.4 15:15, 5 September 2007 (UTC)—Preceding unsigned comment added by 69.150.27.4 (talk) 15:07, 5 September 2007 (UTC)

Where did you get this impression from in the first place? That would at least help in doing a search. SteveBaker 16:47, 5 September 2007 (UTC)

Sorry, the impression is from a physics lecture I attended 30 years ago by High Energy Physicist Dr. Henry Frisch, who is still a professor at the University of Chicago. This doesn't give you much to go on. This is not about 'longitudinal' and 'transverse' mass measurement. He indicated at very high energies the measured 'mass' of particles is significantly greater than predicted by Special Realtivity's mass dialation equation. —Preceding unsigned comment added by 69.150.27.4 (talk) 19:25, 5 September 2007 (UTC)

That would be Dr. David H. Frisch? ...oh...or maybe Henry J Frisch ? SteveBaker 23:05, 5 September 2007 (UTC)

I don't see anything in Frisch's work to suggest he's taking the bold step of proclaiming Einstein to be wrong - but that link to his homepage at Chicago links to a bunch of papers - many of which I cannot understand at all - so maybe someone more in tune with this stuff can speak to it. Right now, I don't see how this can be true - but the definition of mass in a relativistic universe is not a simple thing to define. See Mass in special relativity for a reasonable discussion of the confusion in terminology that's been changing over the past 70 or so years. SteveBaker 23:18, 5 September 2007 (UTC)

No such deviation has ever been seen. It's possible that Frisch was talking about new results that seemed to contradict special relativity but later turned out to be spurious, or that he was talking about some other sort of mass (such as the mass density component of the stress-energy tensor, which transforms in a different way.) -- BenRG 23:28, 5 September 2007 (UTC)

Frisch's work looks pretty conventional. Perhaps he was talking about something else? 30 years ago, physicists weren't sure of the quark model. They would be interested in cross sections, particle multiplicity, particle jets, quark confinement etc. You can find plots of cross sections here; I don't know enough to tell you if they're anomalous, though. - mako 00:54, 6 September 2007 (UTC)

Gene database question

I have an assignment, and I have absolutely no idea how to approach it. Given the names of several genes in a particular bacterial gene cluster, how would I go about finding the sequences of the equivalent genes in a different subspecies of that bacterium? If I can figure it out, I'll be using the data to design PCR primers. Cheers! - 69.113.13.33 16:11, 5 September 2007 (UTC)

I'll assume that the genes are sequenced. Well, one way to do it is to get the sequence for the relevant genes in subspecies 1 (using a database query site, such as NCBI's Microbial Genomes database), and then do a homology search to find the sequence of similar genes in another species. You can do this using the Blast tool. Flyguy649 ^talk _contribs 17:28, 5 September 2007 (UTC)

WIKIPEDIA SCIENCE DEPARTMENT

Who do we go about seeing in regards to a non-national 'Wikipedian Board of Scientists' funded by Wikipedians? In the same sense of Einsteinian Anti-Nationalism, and yet he was funded by Americans and so he gets citizenship with the USA. I understand in science, the answer is key, but the funders of the questioning is also important, and so whatever country funds the research is the flag that those scientists go by, whether they like it or not. Can a group form a sort of United Nations portal, not with the United Nations, but a sort of Non-Nation Science Program, where the seekers of information fund the seekers of information? --i am the kwisatz haderach 16:53, 5 September 2007 (UTC)

I don't quite understand your question - but let's explain some points in the hope that we randomly hit on the right answer! Firstly, Wikipedia is largely an organisation of volunteers. We offer our time and knowledge freely and without charge - mostly for the fun of it - but also to better mankind. We are already an international group - in addition to the English language Wikipedia you are reading now, there are something like thirty different Wikipedias (of any size) for a wide range of other languages. Go to our front page - scroll all the way to the bottom - and you can read Wikipedia in German, French, Spanish...Sinugboanong Binisaya. At one time we had a version in Klingon! Funding of Wikipedia is by donations - but that doesn't pay for any of the content - it pays for the computers, the networking equipment and the staff to look after them...that kind of thing. So for the all-important content (the articles, this ref desk, etc) there is no funding and there is no nationalism. If seekers of information wish to fund us - then they can follow the link on the Wikimedia Foundation homepage where donations are gladly accepted. But those donations have nothing to do with the content of the encyclopedia - only the computers that store it and the connections out to the outside world. Personally, I suspect that most Wikipedians would object strongly to getting tied up with the United Nations - we have all of the international cooperation we need right here in our own ranks. SteveBaker 18:28, 5 September 2007 (UTC)

Well, I understand the commercial interests, publishing rights and so forth. So, I was just wondering if there was a way to totally by-pass these restrictions, for educational purposes. I know in the paper chase of edits here, not that I've added much or even subtracted, but just reading some of the removals., it seems that that's the end of topic, because in the law system or international law, both topics I have no understanding of, although I know it takes a whole heck of a long time for things to get done. I guess we'll just have to wait for the WIKI-MOONBASE. And run the servers from there to bypass the hinderances. I'll accept that there is no quick way. A Wiki-satelite with Wiki-TV channels would be interesting, but that's a whole other ballgame. --i am the kwisatz haderach 19:30, 5 September 2007 (UTC)

Commercial interests? Where? This is about the least commercial place left on the Internet! We're in the top ten most popular websites on the entire Internet - and we have not one advert! Publishing rights are very free indeed - you can even take a copy of Wikipedia and stick it up on your own website if you like...it's one of our founding principles. Compare the articles on (for example) http://encyclopedia.thefreedictionary.com with those on Wikipedia...do they look familiar?! The restrictions (such as they are) on Wikipedia are mainly to prevent you doing something illegal - such as taking a photo from some other website and publishing it here (in breach of someone's copyright). The other things that get deleted are inappropriate articles. Odds are (for example) that if you write a biographical article about yourself - it'll get deleted in short order - but this isn't some "big brother" or "commercial interest" or even "publishing rights" thing - it's a group of Wikipedians who (just like you and me) come here to help maintain the encyclopedia. You can go over to WP:AfD (articles for deletion) and add your opinion to the discussion about what gets deleted and what doesn't. It's not even a matter of voting - it's done by consensus - so in order to delete an article, pretty much everyone who expresses a cogent argument for keeping it can ensure that the article is kept. Deleting articles is as much a community matter as writing them is. Heck - if you want to (I don't), then after you've had a few months of experience here you can ask to be given 'administrator privilages' so you can help with blocking spammers, maintaining order from the chaos, etc. If you can program in PHP, you can even modify the Wikipedia software! This place is much more open than you evidently think.

WikiSatellite TV would be interesting. I think it would be tough to do with our ways of working. The amount of effort it takes just to keep fresh, quality material on the front page every day demands a small army of volunteers. That would probably fill 20 minutes of TV time...where would we get the other 23 hours and 40 minutes every day? TV is voracious - it's expensive (Wikipedia runs on about $1,000,000 per year - TV stations eat that much in a couple of days!) - and it's not suited to what we do. We are continually tweaking and fixing articles - my front-page article on the Mini has undergone literally hundreds of edits since it was deemed 'an example of our very best work' a year ago. Nothing here is ever truly finished. SteveBaker 19:55, 5 September 2007 (UTC)

WOW! Thanks, that's a lot of THE KNOW. Yeah, I'm pretty new at this, and I'm just wondering if that 100 year thing on the Publishing of literary works, namely the deletion of the 70year rule here [on Suicide Notes]. But then that made me wonder about old TV, Radio, and Film, and Music. The articles are great on all the arts, but to actually have access to the old programs and music catalogs would be great. That's what I meant on commercial. I wasn't very clear earlier, sorry. And thanks for all this Great info. --i am the kwisatz haderach 21:24, 5 September 2007 (UTC)

As things come out of copyright, they DO get added into Wikipedia - we're more than happy to take it too! A large fraction of our early content (tens of thousands of articles) came directly from an out-of-copyright version of Encyclopedia Britannica! If you hit 'random article' enough times you'll eventually hit an article with a template box in it that says that the text of the article came from there. Lots of articles are illustrated with pictures from out-of-copyright books. We also make good use things like NASA photographs that have free license terms because they were made by a branch of the US government. There are all sorts of sources of free images, music and text that we actively seek out. But we can't break the law - and that means we have to be exceedingly careful about use of materials that are still under copyright. But don't worry - if it's legal and free and if it's true and relevent - we'll use it. SteveBaker 22:00, 5 September 2007 (UTC)

Schrodinger Equation

$i\hbar {\frac {\partial }{\partial t}}\psi =-{\frac {\hbar ^{2}}{2m}}\nabla ^{2}\psi +V\psi$

So there we are, the Schrodinger equation.My question is this, having had no education in any quantum mechanics, or knowledge of how to acquire one (relatively quickly) short of reading various freely available science books, I want to know how to derive psi using this equation. As it seems the books only deal with concepts, and talk of equations, their meanings, and their history, but not how to use them. So I'll start with some simple examples.

Can you please help me derive a wave function for psi in the following examples. I have no clue where to start, all I know is a basic anatomy of the equation which consists of the names of the operators, and their meanings and implications, but not how to use them, so I have no idea where to start.

1. A Particle in a 1 dimensional space (x) of known location (x=0)
2. A particle in 3 dimensional space (x,y,z) of known location (0,0,0)

If these examples are in fact horrifically complicated, you can simplify them. But At least justify it.

Thanks for your help.

ΦΙΛ Κ 17:02, 5 September 2007 (UTC)

You can't have a particle of "known location." If a particle has a known location, it is not a wave. If it were a wave, that wave would simply be a Dirac delta wave, and there wouldn't really be anything interesting about it except that applying the momentum operator would yield infinite variance. But the first thing to do when attempting to determine the wave function of a particle, you must define what restrictions you place on that particle. The "boundary conditions." Typical boundary conditions are things like, (if the space the particle exists in is infinite) the particle must have zero probability of existing at infinity, (if the space the particle exists in has boundaries that require infinite energy to cross) the particle must have zero probability of existing within or beyond the boundaries. This is all you really need for solving the relatively simple things like particle in a box problems, in any number of dimensions. Things won't get horrendous until you start imagining more complex situations, perhaps with multiple interacting particles. Other hallmark problems are quantum harmonic oscilators (a quantum pendulum), "particle in a bowl." Now, I don't have my notes or text books here on my vacation, so I can't provide any details on actual derivation. But the link I provided for particle-in-a-box does include derivations for up to 3D. Someguy1221 18:21, 5 September 2007 (UTC)

The known location thing wasn't the result of blatant misunderstanding of wave functions, more so of the equation. What I meant was to start with at a given time it is at this location. I don't know if psi describes how the equation propagates with time (which I sort of assumed) , which if it does, knowing a particles former location still allows it to have a wavefunction. Which is what I meant. ΦΙΛ Κ 18:42, 5 September 2007 (UTC)

Well, in that case it can be specified as known location at known time, your initial condition. Someguy1221 18:46, 5 September 2007 (UTC)

I was more lookin to calculate a wavefunction that varies with t. ΦΙΛ Κ 20:45, 5 September 2007 (UTC)

Generally you find time-varying solutions by expressing the initial state as a superposition of time-invariant solutions (energy eigenstates). If your state at $t=0$ is $\sum _{n}A_{n}\psi _{n}\!$, where $\psi _{n}$ has energy $E_{n}$ for every $n$, then the state at any later time $t$ is easy to find: it's $\sum _{n}A_{n}\psi _{n}e^{iE_{n}t/\hbar }$. (By the way, the equation you wrote down isn't the most general form of Schroedinger's equation; it's a special case for a single nonrelativistic point particle with no internal degrees of freedom, like spin.) -- BenRG 23:53, 5 September 2007 (UTC)

You need to specify the potential, V(x); that defines the problem. You can have a constant potential, a square well for a "particle in a box," a simple harmonic oscillator potential, various kinds of delta-function barriers and wells, ... If you work in 1-d and set V(x)=0, then you have a free particle with any momentum you want and a simple set of energy eigenstates. If you start the particle off in a well-known position by making psi(x,t=0) a very narrow gaussian function, it will spread out as a Gaussian with larger and larger width. --Reuben 23:34, 5 September 2007 (UTC)

Will a Dirac delta also evolve into a Gaussian? My intuition says yes, but I can't prove it. —Keenan Pepper 00:26, 6 September 2007 (UTC)

mmh gaussian = e^{-ax^2}, using fn(x)= e^{-x^2n} then n=1 gaussian like, and n=infinity gives dirac delta?)my mistake87.102.6.138 11:45, 9 September 2007 (UTC)

Probably best to ask on the maths desk...87.102.17.39 17:54, 6 September 2007 (UTC)

You seem to be asking is a gaussian extrapolated to zero width the dirac delta - good question (smile - maths desk I think)87.102.17.39 18:10, 6 September 2007 (UTC)

"Yes," but in a dum-dum sort of way. You can take a Dirac delta to be the limit of narrower and narrower Gaussians, and those all stay Gaussian as they evolve; so does the Dirac delta function, in form. But when you ask how fast it spreads out, you find that it spreads out infinitely fast! An infinitesimal instant after t=0, your nicely localized particle has become evenly spread out through the entire universe. It's as likely to be on Tralfamadore as still somewhere in the lab. You can understand this because the initial delta function has every possible momentum equally represented, even ridiculously large values. So after a tiny tiny tiny passage of time, the particle is almost certainly totally gone, and to have gone an arbitrarily large distance away. This is the prediction of the Schrodinger equation for the evolution of a Dirac delta function state with V=0. Of course, it's not physically meaningful. A Dirac delta function is not technically a good wave vector, for one thing. For another, the Schrodinger equation is not relativistically correct, and this solution blatantly violates causality. --Reuben 20:32, 7 September 2007 (UTC)

But a gaussian could not be a solution to the shroedinger equation (try it), especially when V(x)=087.102.6.138 11:49, 9 September 2007 (UTC)

IGNORE - found the answer (((I'd like to see somebody explain the derivation of that equation - specifically why the analogy to the second differential of a moving wave is considered to be good for everything else. Anyone recognise what I'm talking about and able to answer? (please?)87.102.17.39 09:07, 6 September 2007 (UTC) )))

The original questioner may want to learn some general techniques for solving boundary value problems and differential equations, since these skills are essential to the mathematics at hand. Nimur 18:15, 6 September 2007 (UTC)

SOLAR POWER IMPLEMENTATION IN SINGLE DWELLINGS

HOW IS SOLAR CELL ARRAY POWER USED IN SINGLE FAMILY DWELLINGS?? ASSUME THE CELLS ARE IN SERIES TO OBTAIN 110V DC, BUT HOW IS THE CONVERSION TO AC ACCOMPLISHED? USING SOLID STATE INVERTERS?? 71.125.108.113 17:19, 5 September 2007 (UTC)

Please don't type in all CAPS, it is equivalent to shouting. The Solar Power article has the information you need, specifically in the section entitled "photovoltaics." --LarryMac | Talk 18:40, 5 September 2007 (UTC)

on angle-iron stands on a flat surface such as the ground or the garage roof. A clever person in some latitudes could build a house with the roof angle equal to the latitude (flatter near the equator, steeper nearer the poles, problematic as you get very near the poles) for maximum annual efficiency. I would certainly use a rack of storage batteries (about 55 lead acid cells would total 110 volts), but if you are willing to lose power when the utility goes dead you could save a lot of money by skipping the battery storage. Other battery types require other voltages per cell. I would probably buy some 110 V DC lights (Incandescent light bulbs work well on DC, special compact fluorescents are needed) and motors and and replace the AC motors on various appliances, since DC motors work fine and there is not the need for invertor and battery capacity. I would use a solid state inverter which efficiently produced something closely approaching a sine wave, rather than a square wave (which is cheaper and easier). I would try to sell excess power back to the utility. Just powering some of your load by a separate sopar power circuit will lower your monthly bill, but in some places the meter can actually be made to run backward. In others, there is a separate meter for the power you generate. If you like retro things, and don't mind some noise and loss of efficiency, you could use a 110V DC motor to drive an alternator to produce the frequency or frequencies and voltage or voltages you desire to operate your equipment. Edison 21:43, 5 September 2007 (UTC)

What's up with the ElectroMagnetic Frequency, Kenneth?

[rTMS] / Ipod / Cellular RF / Radio Transmissions / Blood / Iron are the relevant topics to questioning. ElectroMagnitism. [Diagram]

I read up on Transcranial Magnitism, as well as the many researches done on Cellular RF levels. Oh the joys. Basically my questioning is in the levels of Iron found in the bloodsystem and would these of a higher?lower? content effect normal? brainfunctioning? Also throwing in the Ipod factor. I know the headphones are magnatized, just holding the stock white headphones together, they magnetically connect. Also charging my Ipod in my car, once I plugged it in the lighter socket, I noticed some of the further radio frequencies that I get in Los Angeles from San Diego became distorted, so I would assume that my Ipod is picking up/absorbing some sort of frequency. I know the Ultrasonic sounds effect dogs as well as fleas and deer., so this may also fall into the biology of our species. So, basically my question is in regards to Magnatism in the Bloodsystem, and the rapid changing of frequencies?? I'm no scientific man, but I am a Layman american that wonders the streets from time to time. --i am the kwisatz haderach 17:40, 5 September 2007 (UTC)

So many questions!

• Don't worry about Transcranial Magnetism...there are a lot of people on the internet who talk complete nonsense about magnets - mostly because (a) they seem mysterious and have a strange intellectual 'pull' for cranks and scam artists...and (b) they can sell you stuff like magnetic bracelets and magnetic inserts for your shoes that have absolutely ZERO effect on you. Think about this - people go through CAT scanners every day - thousands of people every day. The magnetic field from a CAT scanner is enough to pull a metal object from a table 5 feet away and to hit the machine with enough force to leave a dent. Yet not one single side-effect of those amazingly intense magnetic fields has ever been detected. Do you seriously think a pair of wimpy iPod headphone magnets will have an effect? No - humans are pretty much totally insensitive to even huge magnetic fields.

...not one single side-effect... Not so. Transcranial magnetic stimulation is widely accepted as a real phenomenon. Agree with your other points, though. —Keenan Pepper 21:16, 5 September 2007 (UTC)

• Ultrasound is...sound...it's not electromagnetic. Electromagnetic radiation is radio, radar, light, infrared, ultraviolet, X-rays, etc. Sound is air pressure - a totally unrelated phenomena. Ultrasound is also generally unimportant to humans - it's called ultrasound because it's too high in frequency for us to hear - and (lets face it) we use it to scan a pregnant woman so we can get pictures of the baby - it's fairly safe to assume that this isn't terribly dangerous!
• Your iPod may well have affected your radio if it was poorly shielded or the radio had a bad ground wire or something. A radio receiver is very, very sensitive to electromagnetic waves - it has to be in order to pick up a signal of a few tens of watts (like less than a lightbulb) at distances of several miles. Hence the slightest amount of leakage from the computer in the iPod (which operates at the same kinds of frequencies that radio signals run at) can be picked up by the radio as interference.
• Forget about magnetism's effect on the bloodstream - there isn't one.

SteveBaker 18:16, 5 September 2007 (UTC)

• I agree with the above, but am noting that CAT scans use X-rays, while MRIs use magnets. --Sean 18:42, 5 September 2007 (UTC)

Oops! Sorry! (My wife would be horrified - she used to use those machines!) SteveBaker 19:03, 5 September 2007 (UTC)

See also Electromagnetic spectrum. -- SGBailey 19:28, 5 September 2007 (UTC)

I recall being injected with Nickel for a CT scan (regarding possible epilipsy, not diagnosed), nurse said something about it'll show up on the x-ray. But I think that was just for viewing rather than any side effects on thinking. I'm not sure, but they may have a magnet on that machine?? EEG is when they patch you up with all those sticky tabs and wires. --i am the kwisatz haderach 23:47, 5 September 2007 (UTC)

Names of Sun and Moon

Why is it that we dont have an official name for our sun and our moon when weve seen that theres hundreds out there? We call it "the sun" and "the moon" as if it's the only one. I asked my chemistry teacher and she said she didnt have an answer for me. I'd prefer calling our sun Sol, and our moon, Luna. PitchBlack 20:47, 5 September 2007 (UTC)

I imagine it's because the sun and moon have always been there during the development of human languages. Although we now know of other moons in the solar system and that the sun is a star, these discoveries are relatively recent. Note that Sol and Luna are Latin words which mean sun and moon. -- Flyguy649 ^talk _contribs 21:09, 5 September 2007 (UTC)

Note that in writing you can say "the Sun" and "the Moon" to make it clear that you mean the ones pertaining to the Earth (which can also be capitalized to distinguish it from earth meaning dirt). Not everyone follows this convention (but everyone should). --Trovatore 21:13, 5 September 2007 (UTC)

I thought our solar system was called "sol"... or have I invented that myself...? SGGH ^speak! 21:23, 5 September 2007 (UTC)

It's pretty clear that 'Sol' and 'Luna' may be used when there is any ambiguity - and most people will know what you are saying. But until a large fraction of humanity lives where there is some possibility of confusion, I think we'll still be (informally) saying 'sun' and 'moon'. When a bunch of us live on a planet orbiting Alpha Centauri, (or wherever) - I doubt we'll be talking about "Alpha Centauri-rise" and "Alpha Centauri-set" - we'll still talk about sunrise and sunset and "the sun" will gradually come to mean "the local star of whatever planet you happen to be on". When we talk about the old days on Earth, we'll probably talk about the differences between "our sun" and Sol. Ditto for moons. But we don't know that for sure - and we won't know how people will talk until it happens - because language evolves in strange ways. Meanwhile, our language is perfectly well adapted to knowing when people are talking about 'the moon' (meaning Luna) versus talking about 'Charon, the moon of Pluto' - so we can carry on using the old language until something forces us to change. SteveBaker 21:52, 5 September 2007 (UTC)

Terra is also used to refer to the planet Earth, but usually only in a scifi sort of sense. --Mdwyer 21:56, 5 September 2007 (UTC)

The problem doesn't seem to have arisen in the case of the Earth. We don't talk much about other earth's - we talk about other planets - and for some reason, we don't often call this place "The Planet" (except maybe as in "Save the planet"). But 'Earth' is here - and I don't think people living on mars will ever call it anything other than "Mars" - so I doubt much confusion will arise. The worst case confusion might be when we talk of the soil as "earth" when (on Mars) we should be calling it "regolith" - but I suspect that we already have enough other words (such as "dirt", "soil", etc) to avoid that potential problem. As someone pointed out the last time we had this discussion (yes, it's FAQ) - the word "Terra" probably came about from SciFi because there is no nice word for the people who live here. "Earthlings" sounds too much like "weaklings" to work in many contexts - "Earthicans" is just nasty - but "Terrans" works quite well - and we already use words like 'terrestrial' in contrast to 'lunar' or 'solar'. But as with all things linguistic - only time will tell whether a word will 'stick'. SteveBaker 23:01, 5 September 2007 (UTC)

For the same reason that we can often say "the door" or "the street" and expect to be understood, though we each have direct experience with many doors and many streets. —Tamfang 22:00, 5 September 2007 (UTC)

As far as I know, we do have "official" names for all three bodies: Terra, Luna, and Sol. It's just that (for the reasons discussed already), we don't end up using the official names that often. But this isn't a unique occurrence, either: I mean, how often do we call Queen Elizabeth "Elizabeth Alexandra Mary Mountbatten Windsor"? --Steve Summit (talk) 23:45, 5 September 2007 (UTC) (And, yeah, I know, that's not quite her official full name, either.)

I doubt that these names are "official" in any real sense. -- JackofOz 23:50, 5 September 2007 (UTC)

I think Steve has been misled by science fiction, which does sometimes use those Latin names that way. Side comment: when I read my first astronomy books, it seemed clear to me that what they were saying was that using "moon" to refer to anything but the Moon was babytalk: Ganymede or Phobos is a "satellite", not a "moon". I find still find it jarring to see the generalized use of "moon" so widely accepted now. --Anonymous, 02:30 UTC, September 6, 2007.

Using "sun" to refer to anything but the Sun is babytalk as well: "star" is much better. A.Z. 06:43, 6 September 2007 (UTC)

I disagree with both of the above. The term "moon of (e.g.) Jupiter" is well established; there's nothing babyish about it. I think there's a nuance between "moon" and "satellite" -- a "satellite of Jupiter" is any bit of detritus that at the current moment happens to be rattling around that enormous gravity well, but might plunge into the clouds next week. A "moon of Jupiter" is something you expect to be larger, rockier (not a chunk of ice nor a probe from Earth), and have a more circular orbit with a perizene far enough from the cloudtops and from other Jovian moons to be stable for a while.

The issue is different with "sun"; the use of "sun" as a common noun meaning "star" is poetical. But again it's not babytalk; it's supposed to be evocative. --Trovatore 07:23, 6 September 2007 (UTC)

For whatever it's worth, the first astronomical use of the word satellite was Galileo's application of it to Jupiter's four conspicuous courtiers. —Tamfang 20:51, 6 September 2007 (UTC)

A better reason, perhaps, to object to "moon" for satellites of other bodies is that Earth's Moon is not a satellite of Earth, i.e. it is outside Earth's gravitic domain: the Sun exerts more than twice as much gravity on it as Earth does. So far as I know, it is unique in that. —Tamfang (talk) 18:38, 17 March 2008 (UTC)

The name of our sun is Ra as any Egyptian will tell you —Preceding unsigned comment added by 88.109.188.57 (talk) 01:04, 6 September 2007 (UTC)

The original question is flawed. "Why is it that we dont have an official name for our sun and our moon when weve seen that theres hundreds out there?" "The Sun" is the official name for the sun - the others are all stars (as is our sun), and by analogy we sometimes refer to them as suns. Similarly, the official name for the moon is "The Moon" - the others are all natural satellites, and by analogy we sometimes (frequently) refer to them as moons. An analogy might be if you asked why the ancient coin, the Cash, had no official name, since you use cash to buy things in lots of different countries. Grutness...wha? 01:58, 6 September 2007 (UTC)

I still quibble with this notion of "officialness". "The Sun" is the official name of the Sun in the same way that "bread" is the official name of bread, and "water" is the official name of water. There's nothing official about any of these names. We're talking about common, standard, normal names for things that have been known to humanity since time immemorial using only their senses, and in whatever language they use. When it comes to things you need a telescope or a microscope to detect, science comes up with a new name for a newly-discovered object, and that's where a level of "officialness" comes into play. But even there, names still differ from language to language. -- JackofOz 05:53, 6 September 2007 (UTC)

Que? WE HAVE AN OFFICIAL NAME FOR THE SUN IT'S "THE SUN", ALSO WE HAVE AN OFFICIAL NAME FOR THE MOON IT'S "THE MOON", THOSE POINTS OF LIGHT THAT ARE VISIBLE AT NIGHT HAVE A NAMR TOO, THEY ARE CALLED "THE STARS". Did you not notice that you already had the answer.87.102.17.39 09:01, 6 September 2007 (UTC)

No need to shout. I agree with everything you say, with the exception of the word "official". -- JackofOz 09:32, 6 September 2007 (UTC)

Sorry, I just wanted to be heard.87.102.17.39 10:24, 6 September 2007 (UTC)

"we call the sun the sun .... as if it's the only one" - yes that's correct.87.102.17.39 09:02, 6 September 2007 (UTC)

I don't think you are seeing the 'big picture' here. The most significant problem is with 'the moon'. We use the term 'moon' to mean any body that orbits a planet - not just the one that happens to be orbiting our planet - you can argue that this was a poor choice of language - but that's how it is. This ambiguous language only works because when you say "Oh - look up at the moon", people know from the context that you are likely to be talking about the one that's handily nearby - Earth's moon. But if you were standing on the surface of Mars and Phobos was just rising - you'd probably say "Oh - look up at the moon" and nobody would be looking for the Earth and it's moon - they'd be looking for Phobos. So, if you buy that argument, there is a problem. If you are standing on Mars and you actually DO want people to look at Earth's moon - you need a name for it because 'the moon' would refer to Phobos (or perhaps Diemos). The generally accepted name is "Luna". If we ever make it out to stand on a planet orbiting another star, we may well have the same problem with people calling that star "the sun" - so we need a word like "Sol" to mean our sun, as opposed to the local star. This is not unusual. If you are in a house that contains three tables - a kitchen table, a coffee table and a dining table - but the room you are in contains just one of them then you are likely to say things like "Put it down on the table" - without going to the trouble of saying which table. But if you are away from home phoning your wife and telling her where you left her car keys, it's no use saying "They're on the table" because her very next words will be "Which table?" - you're going to say "They're on the coffee table" to make that clear. That's the same situation we're in right now - because we are not yet spacefaring people, we can sloppily refer to "The moon" and the meaning is clear...but in the future, we'll need an actual name for our moon - and it seems that "Luna" is that name. But as I said earlier, until humans start to do that kind of thing, we don't know how the English language will evolve to account for that. SteveBaker 13:06, 6 September 2007 (UTC)

Is it not possible that in the future people living on for example a planet round Sirius will call the light in the sky "Sirius", and if any moons are present will call it the moon or just make a new name for it. They may be able to point out the sun and say "that's the sun, where our ancestors came from."87.102.17.39 17:29, 6 September 2007 (UTC)

It's obviously impossible to predict the future - but Sirius is a nice simple name. Suppose it's "Alpha Centauri"? Also, we have a bazillion words like sunrise, sunset, sunblock, sunglasses, sunroof, sunshade, sunlight, suntan, etc. Are you really going to be wearing 'siriusglasses'? How about 'alphacentauriglasses'? If we do come to live on a star with a nice compact name, then I suppose it's possible - but I think it would be hard to get out of the habit of saying "Oh what a beautiful sunset". The word 'siriusset' somehow doesn't do it! So I think we'll look back at "Sol", "Luna" and "Earth" and call whichever star/moon we happen to be closest to "the sun" and "the moon"...but as I said before - there is no way to know for sure. SteveBaker 21:54, 6 September 2007 (UTC)

I don't agree at all that it's sloppy to refer to our moon as "the Moon". That usage long predated humanity's awareness that some other celestial objects also have natural satellites. If anything was sloppy - and I don't agree that it was - it was the use of the word "moon" to refer to a natural satellite of any planet. We talk about Jupiter having 16 (or whatever) "moons". But they've all been given their own unique names, so where's the problem? Your scenario about standing on Mars and wanting someone to look at Earth's Moon as distinct from Phobos is one of the best examples I've seen of ... well, super-contrivance, if you'll forgive me. We'll need to solve a hell of a lot of much harder problems than this naming issue before we ever get to actualise that scenario. As for "Luna", that is indeed one name that has been used for our Moon; a name that astronomers seem to like, but it has nothing like the official status that Pluto now has as a dwarf planet (and astronomers don't have a monopoly on the Moon anyway). Another is Selene, which gives rise to words such as selenium, selenic, selenotropism [17] and selenotropic, and selenographer - see here for a fuller list of such words. The study of the Moon is selenology, not "lunology", but the words "lunar", "lunatic" and "loon" come to mind. There are also Artemis, Diana, Phoebe, Cynthia and Hecate. -- JackofOz 05:40, 7 September 2007 (UTC)

You're right - but the relative lack of words that begin with 'lune'/'luna' is an advantage - those are words that would have to change because they wouldn't fit if we lived on Mars. As for the words that begin with 'seleni'/'seleno' - those are CERTAINLY not problematic because they are all so very obscure. But when you look at all the words that begin with 'sun' - all in very common usage - that's going to be a problem if we were to choose to use 'Sun' to mean 'The star nearest to Earth' rather than 'Whichever star is nearest to the planet you are living on'. But...as I said three times before...we don't get to choose what things are called. Names evolve, language changes. We won't know what something will be called in the future. Right now, there is little (if any) ambiguity. SteveBaker 13:45, 7 September 2007 (UTC)

In hindsight "the" was attached to the Sun and the Moon. You are assuming that the ancients who first named the two brightest objects in our sky as "Sun" and "Moon," knew that the universe( if they could have conceived of a thing) consisted of countless other solar systems many with planets and their own moons. If they were to think them unique, then what they called them would be their proper names or titles. Only millenia later could we realize that suns and stars where essentially the same thing, and "a" be applied to the Sun and the Moon.

vitamins

is there any vitamin out there that increases penis size? like calcium, one of the b's ... it just kinda stuck me as puzzling... 68.253.183.232 20:49, 5 September 2007 (UTC)

No. See Penis enlargement#Pills. —Keenan Pepper 20:58, 5 September 2007 (UTC)

• If you're young and still growing, good nutrition -- including adequate vitamins -- will indeed increase the size of your penis, along with everything else. You'll probably get plenty from your food, though. If you're old enough that you're not growing anymore, then the size of your penis is the probably the last thing you need to worry about. --Sean 21:23, 5 September 2007 (UTC)

just what the Reference Desk needs, good old wholesome Vitamin P-ness. —Preceding unsigned comment added by 81.182.100.100 (talk) 21:53, 5 September 2007 (UTC)

Wow, jeez reading this has me puzzled too now... now that I think about it- that's a really good question, I doubt that there has been sufficient research done yet though.

Can you keep a Kea as a pet?

Can you keep a Kea as a pet? I've seen them on TV and read a lot about them recently and I wouldn't mind adding one to my parrot menagerie, if there's any breeders in England. Anyone know? Thanks. --84.64.77.99 22:40, 5 September 2007 (UTC)

According to this article [18] there is currently a 15 year ban of keeping them in captivity so the chances are you won't be able to have one legally. Exxolon 23:44, 5 September 2007 (UTC)

But that's presumably in New Zealand. The original poster appears to be in England. --Anonymous, 02:37 UTC, September 6, 2007.

I actually did once see a captive-bred, tame pet Kea listed in the classified ads section of the bird paper I sometimes get (yes, I'm in England). It was priced at over £1000 ten or so years ago, so expect to pay more now, if you can find a breeder. --Kurt Shaped Box 07:57, 6 September 2007 (UTC)

They are notoriously destructive. Probably don't make ideal pets.--Shantavira|^{feed me} 10:52, 6 September 2007 (UTC)

They are notoriously destructive and also both notoriously intelligent and mischievous. Keeping one as a pet would be very difficult, to say the least - I'm not kidding when I say that one could probably work out how to pick the lock of any cage it was in within a couple of hours. Because of their intelligence and curiosity they also get bored very easily, so mental stimulation of some form would be essential - even more so than most other parrots. As for the legality of it, there are very strict laws about getting native birds out of this country (I'm in NZ), so getting a Kea would be very difficult in the first place. I must admit that they're very impressive in the wild, though - and nonchalant around humans to the point of arrogance. There's a winding stretch of road north of Te Anau in southwest NZ where cars have to slow down to a crawl. Keas in the area know that tourists often stop to feed them (even though it's discouraged by Dept. of Conservation staff), so they sometimes force cars to stop by landing on car bonnets - directly in the driver's line of sight - while cars are still moving. Grutness...wha? 12:32, 6 September 2007 (UTC)

Found some pet/captive bred baby Kea videos on Youtube ([19], [20], [21], [22]). They do seem to be rather energetic birds. --Kurt Shaped Box 15:55, 6 September 2007 (UTC)

If you are going to keep them as pets, please at least make sure everything is above board so to speak Nil Einne 19:20, 6 September 2007 (UTC)

Bacteria that form structures?

Are there any forms of bacteria or other single celled organisms that produce structures through the movement of chemicals through their cell membranes? I think that in the more cellular differentiated organisms, such as us, this occurs in the form tissues in the body. (coligen??) I am wondering if there is some intermediary stage where individual cells work together to modify their environment?

Any insights would be appreciated,

Ebenbayer 22:41, 5 September 2007 (UTC)

Diatoms. Not bacteria, but single-celled, and they form intricate structures. --Reuben 22:50, 5 September 2007 (UTC)

Dictyostelid comes to mind - but there are all sorts of Slime moulds that do this kind of thing. SteveBaker 22:52, 5 September 2007 (UTC)

Stromatolites were formed by cyanobacteria. Does this count? -Arch dude 23:07, 5 September 2007 (UTC)

Stromatolites form 'piles' of cells - and Diatoms make large fixed-shape structures - but Dictyostelids actually communicate with each other and form things that look and operate just like multicellular plants for some of their life-cycles - but then they can split back into individual amoeba-like cells - then re-form as a thing that can move around like a slug. They look and behave like unicellular animals, multicellular animals and plants at different points in their lives! Very, very wierd critters. SteveBaker 02:09, 6 September 2007 (UTC)

The Caulerpa seaweed at right is a single-celled organism. Also, flagella are like little chemical propellors. --Sean 13:16, 6 September 2007 (UTC)

Scientific Method

Who was the first person to use the scientific method? —Preceding unsigned comment added by 72.79.39.18 (talk) 23:29, 5 September 2007 (UTC)

Take a look at History of scientific method, but I doubt there's a definitive answer. Exxolon 23:40, 5 September 2007 (UTC)

There isn't a definitive answer, in part because there isn't one set "scientific method". --24.147.86.187 13:47, 6 September 2007 (UTC)

Naked Ear

Can the Naked Ear(I've heard Naked Eye never Naked Ear as a term) hear radio frequency? Or Ultrasonic waves? Lets say your standing close to Electric Grid System, not the mechanical functions of the transformer box, but rather the actual electric field? Or is ringing of the ears just a loss-of-hearing symptom? Thanks. --i am the kwisatz haderach 23:52, 5 September 2007 (UTC)

• Nope. Can't hear stuff out of the range described in Hearing (sense). As for ringing, it could be a lot of things...it's not medical advice to direct you to the article on tinnitus, is it? — Scientizzle 00:05, 6 September 2007 (UTC)
  • Also, it would not be possible to hear a radio frequency for the simple fact that radio waves ain't gonna move your ear drum. and ultrasound is, by definition "a cyclic sound pressure with a frequency greater than the upper limit of human hearing". — Scientizzle 00:05, 6 September 2007 (UTC)
    • actually, you could be able to hear it, your brain just wouldn't know what the heck to make of it. 68.253.183.232 03:18, 6 September 2007 (UTC)
      • How could you be able to hear it? How would the radio waves cause your ear drum to vibrate? —Keenan Pepper 03:54, 6 September 2007 (UTC)

By electromagnetic induction. (it's a possibilty if the ear canal cilla are electrically conductive - which they will be if they are wet..) I'm not saying this is what happens - just suggesting this as a possibility..87.102.17.39 09:26, 6 September 2007 (UTC)

• • • • Exactly. An ultrasonic frequency will make an ear drum vibrate, but the "hearing" comes from the nervous system's ability to accept, propagate and interpret said signal. Only mechanical energy can vibrate the ear drum, eliminating EM waves (such as radio frequencies) as a possible source of sound. — Scientizzle 04:05, 6 September 2007 (UTC)

So what we're really saying is that a person's body is impacted by ultrasound waves, because otherwise it wouldn't be possible to make ultrasound images, but the impact is imperceptible by the person. In particular, the aural mechanisms are not equipped to translate the signals into anything resembling sound. As far as the ear is concerned, there simply is no sound, and hence there is no hearing. -- JackofOz 05:40, 6 September 2007 (UTC)

See Cochlea and links from there for nitty-gritty details on how sound is turned into signals in the brain, or not turned into.. as the case may be. A vibrating eardrum isn't enough. The Organ of Corti is a fairly amazing structure that essentially analyzes sound by frequency, within certain limits. Pfly 06:59, 6 September 2007 (UTC)

If you have high powered pulsed ultrasonic or radio waves (such as radar), it is possible to hear something as the rapid heating effect makes a click that can be heard. This sort of power level however would not be safe. So plesae don't try standing in front of a radar. Graeme Bartlett 22:53, 6 September 2007 (UTC)

The OP reminded me of something I haven't thought about in years, but experience on a daily basis. What is that sound that a television makes that is audible even when the volume is turned all the way down? The volume can be all the way down, with me 20 meters away, and I can still tell whether or not the television is on. It isn't quite a "ringing" in the ears. The only way I know to describe it is as a very high pitched whine, almost inaudible. I've noticed that computer monitors have a similar but softer sound. Any ideas? 152.16.188.107 04:02, 9 September 2007 (UTC)

Are you thinking of the noise of a Cathode Ray Tube? It's a high-pitched whine, and it tends to be heard by the same people who can hear 'The Mosquito'. Skittle 17:01, 9 September 2007 (UTC)

You are probably hearing the high-voltage power supply, which takes the standard household voltage (115V AC 60Hz where I live; both frequency and voltage vary by region) and converts that to 25KV or higher DC. This high voltage is needed to convince the electrons in the back of the tube that they should leave the "gun" and accelerate towards the front. The resulting stream of electrons can be steered by magnetic fields, and draw a picture on the front face of the tube. I'm sure there's an article giving more details.

Anyway, the HVPS uses a transformer with only one or two loops on the primary winding, but thousands of loops in the secondary winding, driving a humongous diode. Not much current generated, but not much is needed; you are just generating a voltage difference inside a vacuum tube. When I worked as a TV repairman back in the '70s, that sound you hear was either a low buzz, meaning that the primary was beginning to vibrate in the magnetic field and should be replaced - it really WAS just a couple loops of wire, easy to replace, or a high painful whine that meant the secondary was going to fail soon. "Soon" being relative, of course. Maybe tomorrow, maybe in ten years. Cats and dogs hate it.

Important safety tip: Playing with the HVPS leads to death. Don't do it. Don't ever even stick your hands in the back of anything with a CRT, until the HVPS has been shorted out. The universe doesn't care how nice you are; only how stupid you are. 66.55.10.178 14:31, 11 September 2007 (UTC)

That's probably what I'm hearing, but I'm forty and can still hear it, even after years of firing weapons while wearing only one earplug. Hehe, I never knew about The Mosquito. LOL, what a concept. 152.16.188.107 23:44, 9 September 2007 (UTC)

idk what any of this means! lol!!!

September 6

Shaving when stressed?

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

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

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

Manufacture of Synthetic Diamonds, Plasma TV Displays and Plasma Air Conditioners

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

Diamond see Chemical_vapor_deposition_of_diamond

TV see Plasma_tv#Functional_details

Air possibly see Ioniser#Ionic_air_purifiers ?

Are you Jas Pal Badyal by any chance?

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

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

Water flow resistence

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

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

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

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

Bones

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

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

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

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

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

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

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

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

Wireless Communication

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

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

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

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

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

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

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

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

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

Brown specks in irises

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

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

Some people believe in iridology, an alternative medicine that works on the basis that your eye colour and pattern reflects the general health state of your body. [23] However, scientific studies failed to find any support for it. That said, specks in the iris can be a result of ocular disease or isorder, such as iritis, or they can be Lisch nodules, a symptom of Neurofibromatosis type I.

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

Orphahed clone

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

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

Wave Structure of Matter

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

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

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

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

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

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

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

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

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

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

Molecular recognition

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

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

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

Mendelian tetrahybrid cross ratio

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

Dihybrid= 9:3:3:1

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

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

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

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

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

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

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

Deserts around the Mediterranean due to global warming?

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

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

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

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

Do eyeballs really not grow?

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

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

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

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

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

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

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

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

According to the University of Illinois Eye Center, at birth the eye is approximately 75% of its adult size, link here [24]. DuncanHill 22:42, 6 September 2007 (UTC)

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

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

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

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

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

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

Pancreatic cancer

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

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

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

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|^{feed me} 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^{(?!? - cool stuff)} 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|^{feed me} 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 ^{\talk \contribs} 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? [[25]]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. [26] [27]. 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 ^talk _contribs 15:56, 7 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.

Freely pulsating worm

Several worms pulsating with one end inside a structure

Excuse the poor resolution and glare. -- Sundar ^{\talk \contribs} 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 ^{\talk \contribs} 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)

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 [28] and [29] 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 [30] 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)

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 Wikipedia:Administrators' noticeboard/Punsters asking for lifelong bans from editing Wikipedia ---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⁻³... 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 | ^PA! 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)

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)

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)

What might it be?

I'm pretty sure it's a Pacific banana slug (Ariolimax columbianus). They can be huge! -- Flyguy649 ^talk _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)

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 ^{(Talk &#149; Contribs)} 12:03, 8 September 2007 (UTC)

But why couldn't they just put an internal antenna in? --antilived^{T | C | G} 00:16, 9 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 Wikipedia 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|^{feed me} 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)

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).

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

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)

• 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)

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^{T | C | G} 00:11, 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)

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)

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

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

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)

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^{talk to me} 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 | ^PA! 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)

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 [31]). 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)

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)

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)

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)

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.