Wikipedia:Reference desk/Archives/Science/2007 April 2

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[edit] April 2

[edit] Storing Liquid Nitrogen

A website I looked at said a dewar would cost like $400. What can I use instead?J.delanoy 00:10, 2 April 2007 (UTC)

I believe you can use an ordinary Thermos bottle. But please read up on the safety aspects -- you've got to make sure the neck doesn't freeze up, otherwise the bottle will explode. —Steve Summit (talk) 01:27, 2 April 2007 (UTC)
I am not sure of that kind of safety. Normally if you want some at home, you rent a dewar, since not a lot of people need to keep dewars full of ln2. [Mαc Δαvιs] (How's my driving?) ❖ 02:55, 2 April 2007 (UTC)
The Thermos bottle article says a domestic bottle can keep contents cool for only 24 hours. That's for typical cold contents, not the insanely cold liquid nitrogen. Safety is important too, though don't worry too much since liquid nitrogen will evaporate shortly before touching the skin. --Bowlhover 04:29, 2 April 2007 (UTC)
Erk. Please be cautious about giving safety advice on the Reference Desk. (I am a scientist, and I use liquid nitrogen on a regular basis. I readily admit that we use some pretty iffy containers for LN2, but you should always be aware of the limitations of your tools.)
A standard off-the-shelf vacuum flask may survive use in this application, but note that its materials haven't been tested for extreme low-temperature use. Never close the stopper in such a bottle, for at least two reasons. First, most stoppers are plastic and have some sort of polymer O-rings to hold a seal. Both stopper and O-rings will tend to become brittle at low temperature, and you may end up shredding the stopper when you try to remove it. (This problem can be exacerbated when water vapour freezes to very solid ice around the mouth of the container.) Second, such a flask will not have any sort of pressure relief valve or vent. A sealed flask will be prone to violent failure.
Note that LN2 will not evaporate before touching the skin; it will however evaporate when it comes in contact with skin, providing an insulating gas layer that provides some protection from additional LN2. (This is why you can safely immerse your hand in LN2 for a couple of seconds without freezing it—the layer of boiled nitrogen gas around your hand protects you for a little while. This is the same mechanism by which a droplet of water skitters around on a hot skillet.) Exposure to larger volumes of LN2 for longer periods most definitely cause frostbite. TenOfAllTrades(talk) 13:09, 2 April 2007 (UTC)
Maybe, TenOfAllTrades should have been more graphic: When the LN2 warms, it evaporates, and a bottle full of LN2 would be many litres of nitrogen gas under athmospheric pressure. When the flask is closed, all this gas is compressed, giving rise to enormous pressure. If you are lucky, the bottle's cap simply blows of. More likely however, the bottle will shatter into literally thousands of pieces, which are accelerated considerably by the pressure. In other words, a closed LN2 flask without extermly-low-temperature--proof safety valve may be a quite effective shrapnell bomb with surpise timer. Even an open flask will probably experience huge material tension due to the shrinking of the part of the inner wall in contact with the LN2 and in consequence rupture and shatter. So: No, I would not try out whether a thermos flask can replace a proper dewar, at least not without full-body armor. And even when using a real dewar, don't forget protective goggles and special LN2-proof gloves. Simon A. 16:07, 2 April 2007 (UTC)
You could always try borrowing a real from school or work? Or what about those thermos things that are parallel sided designded for storing hot or cold drinks. You could operate that without the real lid but with some sort of insulating (but not tight fitting) lid. (Maybe) —The preceding unsigned comment was added by 88.110.173.8 (talk) 01:01, 3 April 2007 (UTC).

Actually, i was just thinking about how I would keep it from simply evaporating before I had a chance to use it all. i am aware of safety issues such as expanding liquid-to-gas things (having exploded more than one soft drink bottle with vineger and baking soda) I am also aware of the effects of very cold things on normally soft items, for example, my science teacher told me to put a marshmallow in liquid nitrogen and drop it into another student's hand to demonstrate the heat insulation of air. The student was scared (obviously) and dropped the marshmallow. Have you ever seen a marshmallow shatter???! i hadn't either.
Again, i simply wanted to know what I could cheaply store liq nitro in to keep it from dissapearing too fast. Thanks.
J.delanoy 02:32, 4 April 2007 (UTC)

[edit] Global coal reserve will last 600 , 155 and 285 years

According to coal#World coal reserves, the global coal reserves will last 600 years. Then on the very next paragraph says that it would last 155 years. But the final word on the third paragraph is that it would last 285 years.

I know that wikipedia is very accurate because someone else told me that it would last 186 years. So for my school assignment it would contain all 4 different correct answers. 202.168.50.40 00:17, 2 April 2007 (UTC)

The article says that "proven" (i.e. known) reserves would last 155 years. The other two are guesses as to how much coal there is, whether it has been found or not, that can be recovered using current technology. Since they are only guesstimates, it's not surprising that they differ. As for Wikipedia being very accurate, don't count on it. Clarityfiend 02:09, 2 April 2007 (UTC)
There are really three unknowns here - firstly we don't know how much coal is left underground. Secondly we don't know how much our extraction technologies will improve...after all, it's not just that the stuff is there - it's whether the cost of extracting it makes it worthwhile. But mostly we don't know how fast we're going to be consuming it in the future. Burning coal is a HUGE CO2 source - and with the spectre of global warming upon us, we're going to have to do some serious cutting back of fossil fuel consumption. If the world responds as it should to global warming, we're going to be cutting back on coal use as pretty much our first and foremost priority. So we have three unknowns. The question of whether we'll still be using the stuff in 150 years or 600 years is a total unknown. Personally, I doubt we'll ever "run out" because we'll simply be forced to stop using the stuff long before we stop being able to find new reserves. SteveBaker 03:17, 2 April 2007 (UTC)
Another variable is whether it's economically viable to extract remaining deposits. This has to do with energy prices, the cost of extraction, and environmental laws. StuRat 21:44, 2 April 2007 (UTC)
With the latest technology, it's not extracted but burnt underground. Can't remember what that's called, though. DirkvdM 18:52, 3 April 2007 (UTC)

[edit] Too loud to hear yourself think

I sit actually possible for it to be too loud to hear yourself think? I really don't think so, but I just want to make sure. Thanks!! Reywas92Talk 00:14, 2 April 2007 (UTC)

You never can't hear yourself think, because it doesn't actually use your eardrums (i.e. you're not actually hearing). If you can block out all the sound, then you call always hear yourself. —METS501 (talk) 01:10, 2 April 2007 (UTC)
It may be possible, but it is impossible to confirm, because if you can't hear yourself thinking, how can you know you are thinking? Anchoress 01:15, 2 April 2007 (UTC)
I think the "hear" part of "hear yourself think" may be merely a figure of speech. Obviously loud noises make it harder to concentrate - I suspect people interpret that as being unable to hear their own thoughts...but thoughts aren't necessarily an auditory thing, so I don't think that's the cause. It's easy enough to test whether people can find it harder to concentrate in a noisy environment - but I think it's a sufficiently common phenomenon that we can take that as read. SteveBaker 03:11, 2 April 2007 (UTC)
It might be merely a figure of speech, but it might not. I read somewhere last week about a hypothesis that some auditory hallucinations might be caused by people hearing their own thoughts, like we all do, but misinterpreting the source as actual sound. So even though hearing oneself think doesn't involve the eardrums, if it involves some of the same higher-level brain functions as processing actual sound, then it seems at least conceivable that actual sound could saturate those functions to the point where one couldn't hear one's own thoughts. --Allen 04:13, 2 April 2007 (UTC)
In the terrible, terrible, horrendous computer game called Zork - there is a scene where you come to a control room that is so loud that you "can't hear yourself think" - so in that room you can't do anything (you need to pick a bar off the floor but you can't cos you can't think). So if you type "Echo" the noise stops and you can think.
Spoiler! Spoiler! Spoiler! :-) —Steve Summit (talk) 02:51, 3 April 2007 (UTC)
This has nothing to do with anything, but it is a reference to your question in popular culture, even if it is about 24 years old. Rfwoolf 09:59, 2 April 2007 (UTC)
It's more a case of overwhelming stimuli derailing any coherent ideas before they can form. As for thinking, there's always a million things going on in your brain every second, and a lot of it could be construed as 'subconscious thought', so yeah, you're technically still thinking even when there's a wall of sound blocking anything high-level from forming. Vranak

[edit] Fire tornado machine

My science teacher has a tornado machine which functions by creating a vortex which can then be illustrated using dry ice and lights. Recently he came up with the idea of using it to create a fire tornado. There are several problems that we (the pyromaniac students interested in helping) have come up with:

  1. How is the fire generated? That is, how do we ignite a fuel without creating an explosion of the fuel source that must be connected to the machine?
  2. How do we sustain the fire? I already know that we will have heat, fuel, and oxygen, due to the natural environment and the requirements for building the machine for fire, but how can it be kept from going out in the vortex?
  3. How do we contain the fire? How do we keep it from burning up the pre-existing wooden platform of the tornado machine?

Many thanks, AMP'd 00:49, 2 April 2007 (UTC)

I've changed the redirect at fire tornado to point to Fire whirl rather than Firestorm as it did when you posted your question. We all hope that your project will result in a simulation of the former and not the latter.—eric 23:02, 2 April 2007 (UTC)
I have known that the redirect led there. I was just unware that we had any other article. Thanks EricR. - AMP'd 02:04, 3 April 2007 (UTC)
At the risk of being accused of contributing to the delinquency of minors, I would suggest (for your own safety and that of your apparatus) using the lowest-temperature flame and fuel you can. Rubbing alcohol might work. —Steve Summit (talk) 01:24, 2 April 2007 (UTC)
I didn't ask for medical or legal advice and this isn't a question of opinion. Just keep Kurt from telling me to cook any type of bird in the flame and we should all be fine. - AMP'd 02:07, 2 April 2007 (UTC)
This is totally cool and appeals to the pyromaniac in all of us. Please describe the machine in further detail. Basically, we must assume that the vortex within the machine keeps the fuel from contacting the machine itself, so the container should only be heated by radiation and not by conduction. If you use a fuel such as natural gas or propane, your tornado will be conceptually similar to the combustion chamber in a traditional gas furnace, except that you will be using a vortex mixing scheme rather than a traditional mixing scheme. Gas mixing is a big deal. A traditional furnace must introduce a lot of air to ensure complete combustion, and this extra air causes much of the heat to be lost up the chimney. One alternative is the pulse furnace, which permit complete combustion with less loss up the chimney. If you can somehow get complete combustion in your vortex without introducing extra air, you may have a patentable invention. -Arch dude 03:40, 2 April 2007 (UTC)
The issue is that the tornado machine is basically a wooden platform with a hole in the bottom that introduces swirling air and then a hole at the top that removes it. The vortex itself is illustrated with sublimating CO2 and is not contained by any glass. - AMP'd 15:41, 2 April 2007 (UTC)

Just look at how a vortex vacuum cleaner works. You would just introduce the combustion air at an angle, and have a chimney effect for the hot air. Sounds like custom glass work, but the temperatures might be too hot (kaboom!). --Zeizmic 11:52, 2 April 2007 (UTC)

Maybe you can introduce a liquid (possibly with circulation system) to cool the glass? Root4(one) 13:22, 2 April 2007 (UTC)

You also need to vent the combustion products. I strongly suggest running this hole thing outside, with a remote control so you don't have to stand near it. StuRat 21:38, 2 April 2007 (UTC)

For containing the flame, I'd suggest enclosing the whole vortex chamber in wire mesh, similar to a Davy lamp. Just make sure the mesh doesn't overheat, although, with the amount of airflow through your machine, I wouldn't expect that to be much of a problem. —Ilmari Karonen (talk) 22:16, 2 April 2007 (UTC)
I agree with Steve Summit - I think isopropyl alcohol would be ideal (not least because you probably won't kill anyone with it). Get the %91 kind for best results. The only engineering problem is aerosolizing it. If you can get a little pressure-pump garden sprayer from Home Depot or something, that would do nicely. Then aim the spray into the flame, and ignite with a good sturdy pilot light (a lighter will do for short periods of time). I think it is highly unlikely that temperatures will approach the flashpoint for wood, so I think it's relatively safe. Just take some good pictures and post them here when you're done :) --Bmk 07:17, 3 April 2007 (UTC)

[edit] Crossing legs

Why can't small childern cross their legs?

Very small babies can have hip dislocation problems - I wonder whether they instinctively avoid the kinds of things that might be a risk - if that were the case, it might take a few years to unlearn that behavior. Just a guess I'm afraid. SteveBaker 03:07, 2 April 2007 (UTC)
I'm thinking infants, isn't it because of their legs are so small and fat? [Mαc Δαvιs] (How's my driving?) ❖ 16:52, 2 April 2007 (UTC)
Mac's right. alteripse 19:37, 2 April 2007 (UTC)
But there's something more, they are able to sit in a way that adults can't, with their legs splayed to the sides, looking like this from the top:
          /\ /\
            O           StuRat 21:31, 2 April 2007 (UTC)
So if I cant cross MY legs, are they too fat?
I can do that with my legs. Actually, oww. No I can't (I just tried). I used to be able to the last time I tried - a couple of years ago. --Kurt Shaped Box 23:36, 2 April 2007 (UTC)
What? Make them look like a bird in flight? ;-)
I thought it was an extravagant pignosed smiley. Btw, thanks, Stu, I have just dislocated my legs trying to prove you wrong. DirkvdM 18:57, 3 April 2007 (UTC)
LOL, how many people can I cripple today ? StuRat 01:29, 4 April 2007 (UTC)

I can sit like that diagram, and im 21. I do have 'double jointed' knees though...still it's good for freaking people out. Rickystrapp 21:53, 3 April 2007 (UTC)

Can you sit like that with your butt flat on the floor ? If so, you're rather limber for an adult. StuRat 01:27, 4 April 2007 (UTC)

It seems that nearly every toddler can sit that way, and they even appear to find the position comfortable. So, something must be different in the hip joints at that age, I imagine. StuRat 01:25, 4 April 2007 (UTC)

[edit] New element

They discovered a new element, element 126 I think, that has a half-life so long its radioactivity isn't considered dangerous. This element is extremely dense and, due to its high density, can have a lot of applications. It's also possible to produce in ton quantities. So where can I get this thing? Thanks. --Anonymous

Unbihexium may help you out. Aaadddaaammm 04:17, 2 April 2007 (UTC)
That's it, except now it's been synthesized. Oh boy would I like to get my hands on some of that exotic stuff! --Bowlhover 04:21, 2 April 2007 (UTC)
So where'd you hear about this? A google news search for "unbihexium" yields zero hits. And normally it's extremely difficult and expensive to synthesize these transuranium elements, so producing one in "ton quantities" sounds quite remarkable... —Steve Summit (talk) 05:11, 2 April 2007 (UTC)
It was April Fool's yesterday, that's my guess anyway.. Vespine 06:01, 2 April 2007 (UTC)

I believe there is a theory that an "island of stability" exists somewhere around there, so this possible prank may be based on that. StuRat 21:28, 2 April 2007 (UTC)

The "extremely dense" part suggestst that this is the old administratium joke. --Anonymous (not the same person), April 2, 2007, 21:31 (UTC).
Not really; I've never heard of the administratium joke before, and I said element 126 was extremely dense because it has a high atomic number.
StuRat: yes, the island of stability is in fact element 126. Try the unbihexium article.
--Bowlhover 02:43, 3 April 2007 (UTC)

Don't forget Unobtanium.

Atlant 13:54, 3 April 2007 (UTC)

So, where can I actually obtain some unobtanium?  :-) --Bowlhover 05:14, 4 April 2007 (UTC)
I understand Nigeria may have the raw materials for some.
Atlant 15:44, 4 April 2007 (UTC)

[edit] Full-by-Water Question

So I've noticed that if I drink a lot of water, I get a sensation of fullness that then dissapates. Better yet, if I drink a lot of water and then eat a bit, I get full and it seems to last for a while. The question isn't whether drinking a lot of water before meals would be an effective way to lose weight by cutting down on how much you eat, because I'm pretty sure the answer is yes and I don't plan to put it into practice anyway. The question is whether one would "shrink" one's stomach by doing this on a regular basis. And, for that matter, what really is "shrinking" a stomach? Is it literal? For instance. A couple years back I went to camp for a month, hated the food, ate an apple a day, and returned home much lighter and needing much less food to get full. If, instead, I had drank lots of water every day at that camp and then eaten just as little but, because of the water, ended up as full, theoretically, as a completely meal would make me, would I just lose weight but retain an unshrunk stomach (because I'm not dealing with the hunger, just tricking it), or would both my weight and hunger go down? 70.108.199.130 06:50, 2 April 2007 (UTC)

Well, the first thing is - don't drink too much water - it can be harmful and even kill you (See: Water intoxication). I presume that the temporary feeling of fullness comes from the fact that the water sits in your stomach for a while and then makes it's way down into the lower intestine pretty quickly - so the feeling of fullness goes away faster than with solid food that makes it's way down the digestive tract a lot more slowly. I doubt the process you describe would work - if it did then it would be regularly suggested by the experts instead of all that tedious 'eating right and getting plenty of exercise' stuff - and it's not - so there is bound to be some horrible flaw in your argument! SteveBaker 07:08, 2 April 2007 (UTC)
I believe that experts regularly do suggest drinking large quantities of water. Of course, just losing weight isn't the only goal, so they will also recommend that you eat a healthy diet and exercise. StuRat 21:24, 2 April 2007 (UTC)
Yes, but there is definitely something about shrinking the stomach. I've heard that the key to winning an eating contest is *NOT* by starving yourself silly, but rather the opposite: in the days leading to the contest you should stuff yourself silly - thereby expanding the stomach - so at your eating contest your stomach would have expanded and you would be able to eat more.
I know recently I fasted for 24 hours - NO WATER OR FOOD - and after it I felt my stomach was rather small in that I didn't have to eat as much to get full - but the real question is whether just eating less and drinking more can slowly lower a person's appetited by 'shrinking' the stomach.
This is an excellent question - and I'd love to know the answer - but I'm afraid I can't be more help than that. Rfwoolf 09:54, 2 April 2007 (UTC)
Not drinking water for 24 hours is dangerous, and could result in dehydration. StuRat 01:20, 4 April 2007 (UTC)

[edit] cryptid

In the ‘Yowie (cryptid)’ article in the Wiki there is a statement made in the Candidates section as follows:

Candidates “Australian cryptozoologist Rex Gilroy has attempted to popularise the scientific term Gigantopithecus australis for the creature (without support from the Australian scientific community), based on his theory that they comprise a relict population of the extinct ape Gigantopithecus. There is, however, no evidence that Gigantopithecus ever existed in Australia.”


I am seeking the source for this above statement. Will you please direct me to it? Any and all help is greatly appreciated.Rorechof 07:20, 2 April 2007 (UTC)

I have a copy of the Encyclopedia of Cryptozoology: A Global Guide by Michael Newton, and it says, under "Yowie", "Gilroy and Harrison favor the extinct ape Gigantopithecus or a close relative, though fossil remains are known only from China and Vietnam. (Gilroy claims to have found a fossil footprint from Gigantopithecus near Kempsey, New South Wales, but the claim remains unverified)." -Joelmills 01:40, 3 April 2007 (UTC)

[edit] Referencing Wikipedia in Endnote

I would like to reference Wikipedia in my PhD thesis. I am using Endnote to compile and annotate my thesis with references. Do you have a standard form of referencing for Wikipedia in theses or studies.

Nic Gellie PhD Student The Australian National University Canberra, ACT Australia

One place that would help you is Wikipedia:Citing Wikipedia --antilivedT | C | G 07:58, 2 April 2007 (UTC)
Each page also has a "Cite this article" link, which provides citation info in the following formats:
APA, MLA, MHRA, Chicago, CSE, Bluebook, AMA, BibTeX
Good luck. − Twas Now ( talk • contribs • e-mail ) 08:12, 2 April 2007 (UTC)
Just by way of a (perhaps trite) cautionary note. I would never EVER cite Wikipedia in an academic paper. At least my research field, you would never use an encyclopedia as a reference for something you were going to publish. -- mattb @ 2007-04-02T12:43Z
But in Australia, due to the Coriolis effect, they do things backward. It's strictly physics. − Twas Now ( talk • contribs • e-mail ) 14:25, 2 April 2007 (UTC)
Not only backwards, but upside down. That's why the blood rushes to our heads and makes us all so magnificently intelligent. JackofOz 01:50, 3 April 2007 (UTC)
I could imagine citing it if your thesis was about Wikipedia in some way (an example of an online site), but never anything else (I've cited encyclopedias for an article about encyclopedias, heh). But in any case it's their own thesis, and their own neck. Anyone writing a PhD thesis should have enough sense about sources to know what would be appropriate, I would hope. --140.247.243.111 19:12, 2 April 2007 (UTC)
I would also recommend not citing Wikipedia, they'll often get all up in you for doing that. But shouldn't we be encouraging people to cite Wikipedia? [Mαc Δαvιs] (How's my driving?) ❖ 16:51, 2 April 2007 (UTC)
I would strongly recommend finding a peer-reviewed source instead of citing Wikipedia. Everything on here should carry a reference to a proper source anyway, and things that don't should definitely not be cited in academic research as they may be unreliable. My university specifically states that Wikipedia is not an acceptable primary reference. --YFB ¿ 17:00, 2 April 2007 (UTC)
Re: Mac Davis - No! Even if Wikipedia was the best-referenced, most accurate, and most comprehensive encyclopedia in the world, it's still not generally acceptable to use encyclopedias as citations. Academic research should cite primary sources. I haven't cited an encyclopedia since junior high school. -- mattb @ 2007-04-02T17:05Z
Most research cites secondary sources, but anyway, point is valid. --140.247.243.111 19:12, 2 April 2007 (UTC)
Your only cite to Wikipedia should ba a generic "thank you." You should cite all encyclopedias that you used in this manner. After that, you should cite (and actually read) the references cited by the encyclopedias.

If you find a really wonderful and relevant fact in Wikipedia that you need to cite, and that fact has no citation, then you must not cite the fact. Instead, find a valid citation and edit Wikipedia to cite it, or remove the offending sentence from wikipedia. -Arch dude 02:24, 3 April 2007 (UTC)

Agree. Encyclopedias are for quick reference. A Ph.D. thesis is the absolute antithesis of "quick reference." Nimur 06:37, 3 April 2007 (UTC)
Thesis == antithesis, up == down, two legs bad == two legs good. DMacks 16:49, 3 April 2007 (UTC)

FTW??

[edit] Displacement of Water

Archimedes says that the amount of water displaced by a mass is equal to the volume of the mass. I had a doubt. If I fill a bucket of water to the brim and drop an object from a certain height, does the height factor determine the volume of the water displaced. In simple words, does the height from which a mass is dropped affect the amount of water displaced? If so, how? Is there any standard constant or some proportional constant that has been already found out and if so, can anybody suggest some standard experiment or procedure to determine the above?

Dropping doesn't change the volume of the object. The kinetic energy of the fall causes turbulence and will splash the water, but the volume displaced doesnt change. alteripse 11:55, 2 April 2007 (UTC)
Nod, there's both water displaced by weight and water (temporarily) displaced by kinetic energy: two different concepts. If you dropped that same object in a larger pool of water, you may find it goes into the ocean deeper than what it would without the height, but you may soon find it being pushed back up alot higher too (in fact it may even bounce out briefly). I suppose it will continue bouncing up and down until most of the kinetic energy is dissipated with the waves generated. Root4(one) 13:58, 2 April 2007 (UTC)

Archimedes' Principle does not apply to water which splashes out of the bucket. StuRat 21:18, 2 April 2007 (UTC)

May we conclude from this that Archimedes did not splash in his bath? DirkvdM 19:03, 3 April 2007 (UTC)
No, he was too busy looking for something while he bathed, then he said "Eureka ! (I have found it !)". StuRat 16:08, 4 April 2007 (UTC)

Archimedes' Principle actually states that the upthrust is equal to the weight of the fluid displaced. This can easily be proved by considering the pressure difference between the top and bottom of a cube, say (keep it simple) either floating or completely immersed in a fluid. Pressure = depth * density = force/area. Try it with a 1 m cube (on paper)

Is there any constant ratio in which the amount of water displaced is proportional to the height from which it is dropped. Or if I make an experiment and find out the numerical values of the height from which a mass is dropped and take the ratio between the mass and the height dropped, will it give me a constant, for a particular mass?

The amount of water splashed out would be, I think, proportional to the speed of the object hitting the water, more or less. However, once an object reaches terminal velocity, air resistance prevents it from gaining any more speed, regardless of any additional height for the drop, so the size of the splash would not increase further. StuRat 22:55, 3 April 2007 (UTC)
It would also depend on the shape of the object, surely? So, if you dropped a pole in from a great height, and it landed thin-end-first, it wouldn't produce as much splash as a ball of the same mass hitting the water at the same speed. Skittle 16:13, 4 April 2007 (UTC)

[edit] Surface Tension of an Electrically Charged Droplet

While was studying surface tension, I wanted to explore the various factors which may bring about a change in the surface tension of any liquid.

So, if I electrically charge a droplet of water and measure the surface tension, will it be any different than the original surface tension of water ... ????

Kindly illuminate.

Have you seen this? [1]

[edit] Copper Extraction

I'm searching for references on

  • Non economic deposits
  • Different grades of copper and their prices
  • Costs of production with quotes
  • technology advances related to copper extraction

I've seen Copper extraction and followed links .. any thoughts? DDB 12:33, 2 April 2007 (UTC)

[edit] Boric acid insecticide

My kitchen is inundated with ants that are fond of both sugar and meat. I mixed 1 part Boric acid with 16 parts sugar (by volume) and dissolved this mixture in 2 cups boiling water. When it cooled I poured it into a squeeze bottle and placed drips of it in jar lids and left one where I could see it. The ants loved it and then after a couple of days diminished in number until all were gone. Just before disappearing in the kitchen they began showing up in the bathroom so I added jar lids with the Boric acid/sugar solution there. Again they began to diminish and then disappeared. A few days later they reappeared and now they seem to be flourishing on the solution rather than dying. What in the heck is going on? Did they become immune to the Boric acid or what? Also can I mix Boric acid with meat scraps and kill ants and other meat eating insects as well or will Boric acid not mix with meat in the same way as is does with hot water and sugar? 71.100.167.232 15:10, 2 April 2007 (UTC)

Perhaps they developed more of a tolerance than an immunity, in which case increasing the ratio of boric acid might help. Also, if the sugar and boric acid both form crystals once dried, is it possible they are able to pick out the sugar crystals and leave the boric acid crystals ? StuRat 21:12, 2 April 2007 (UTC)


Ants do not build up immunity to boric acid, however, perhaps the solution was not thouroughly mixed, and you have too litle poison in what is left. There could be more than one nest of ants involved, so give them at least a week to find the poison and eat it. You can use borax instead of boric acid. Even mixed borax and sugar crystals can confuse and poison ants, borax does not taste too bad but is no good to eat. GB 21:15, 2 April 2007 (UTC)

The only thing odd I noticed about the solution of Boric acid and sugar was that what was left in the squeeze bottle developed some slimy dark brown "strings" (possibly just old mustard clinging to the inside of the bottle) but it looked more like some kind of mold or bactreria growth due to the sugar. I'll try Borax and mixing the sugar and Boric acid or Borax better in the next batch. 71.100.167.232 17:33, 3 April 2007 (UTC)

You can also use honey or jam instead of sugar to mix witht he borax/boric acid. boric acid reacts with sugars. GB 02:23, 5 April 2007 (UTC)

[edit] Beetle to be identified

Image:Beetle in Tyrol.jpg
What beetle is this? Picture taken in Tyrol, Austria.

Hi. A friend of mine took this picture a few days ago in the forests at the mountain base at the Northern outskirts of Innsbruck, Tyrol, Austria. It looks peculiar and not like the beetles we are used to find here. Anybody out there who can tell us what it is? TIA. Simon A. 15:39, 2 April 2007 (UTC)

Blister beetle, Moloe sp.. So called because the adults secrete Cantharidin from the joints of thier legs when irritated or harrassed.Rana sylvatica 16:09, 2 April 2007 (UTC)Rana sylvatica

OOps! Typo, it's Meloe sp.

Ringo? Clarityfiend 00:32, 3 April 2007 (UTC)
Thanks. Looking through the species in the Meloe genus, I think now it's Meloe proscarabaeus. Simon A. 11:41, 3 April 2007 (UTC)

[edit] Does Erica carnea contain a Viagra-like substance?

The Independent reported on April 1 that the Winter Heath Erica carnea contains a Viagra-like substance that can enhance erection when extracted from the flowers with alcohol. Some other newspapers have picked up the story, but Google and PubMed searches for "Erica and ("nitric oxide" OR erection OR erectile)" yield nothing. Was this an April Fool's joke? AxelBoldt 17:10, 2 April 2007 (UTC)

[edit] Update to City of Hope wikipage

On the Wikipedia page for City of Hope Cancer Center, the 3rd paragraph references over 7500 HCT procedures, but it is woefully out of date: http://en.wikipedia.org/wiki/City_of_Hope_National_Medical_Center


The current figure of HCT procedures performed to data at COH is 7934: http://www.cityofhope.org/hct/default.asp

Can you update this?151.152.101.44 19:37, 2 April 2007 (UTC)Carmen

That doesn't seem "woefully out of date" to me, as "over 7500" is correct, and within 6% of the current number. Just how often do you expect us to update this figure ? Feel free to change it to "over 7900", if you wish. Remember, anyone can edit Wikipedia (except protected pages). StuRat 21:05, 2 April 2007 (UTC)

[edit] Oldest, longest-living species?

What species of life form lives on average to the longest life spans? Or any single individual? My first guess would be some sort of tree, but who knows...--Sonjaaa 20:11, 2 April 2007 (UTC)

Well, some trees have lived for over four thousand years, and haven't died yet. So there is no "life span" unless they die! The trees can probably grow indefinitely until they no longer have any light, so I'd say 20 billion years, when Sol supernovas.--Ķĩřβȳ♥♥♥ŤįɱéØ 20:21, 2 April 2007 (UTC)

Agreed; some, but not all, organisms are "programmed to die" after a certain range of time (including us, unfortunately). For the rest, with no set life span, the laws of probability come in to figure out what the maximum age of any individual is likely to be. For example, if half the organisms die every year, regardless of their age, then about 1/210 or 1/1024 will survive for 10 years. StuRat 20:59, 2 April 2007 (UTC)
And of course, this question gets very tricky if you start to consider organisms which reproduce by splitting (like bacteria). When do their lives start? When do they end? Skittle 20:53, 2 April 2007 (UTC)
The oldest living individual life form is a Bristlecone Pine known as Methuselah, at 4838 years. If you expand to clonal colonies, then the oldest living is a Quaking Aspen known as Pando, at some 80000 years. — Lomn 21:07, 2 April 2007 (UTC)
A great place to start is the list of long-living organisms! − Twas Now ( talk • contribs • e-mail ) 23:26, 2 April 2007 (UTC)

Some animals can survive dehydrated or frozen for thousands of years. Rotifers and tiny crustacean eggs have this capability. GB 21:24, 2 April 2007 (UTC)

In addition you must consider the possibility that humans will learn how to extend human lifespan, or create a new species that has an arbitrarily long lifespan, at the technological singularity. -Arch dude 02:08, 3 April 2007 (UTC)


So most trees will never die of "old age"?--Sonjaaa 02:31, 3 April 2007 (UTC)

OK then what about the animal kingdom? Or the mammals?--Sonjaaa 02:32, 3 April 2007 (UTC)

You there? Try looking at this list of long-living organisms. − Twas Now ( talk • contribs • e-mail ) 05:49, 3 April 2007 (UTC)
Is there a list of long-lived organisms anywhere in the world? Where could I find such a thing? --140.247.243.111 16:40, 3 April 2007 (UTC)

Speaking of longetivity, is it just me or are non-prey vegetarian/pesco-vegetarian animals (elephants, ~60 years; turtles, sometimes over 150 years) a lot longer lived than non-prey predators (lions, ~7 years)? Vranak

There is a real problem with answering this question if we consider creatures like the amoeba. It reproduces by splitting into two pieces - each of which creeps away and acts like a new organism. How do you interpret this in the context of this question? Do we say that the original amoeba "died" and two "new" ones appeared? (If so - then they don't live very long.) Do we say that the original amoeba created a clone and carried on living? Or do we say that the 'individual' continues to live in both of the offspring? In the third case (which I think I like the best) you'd have to say that amoeba's are effectively immortal since they are all descended from one 'original' amoeba...which in a sense is still alive. In the second case, how do we identify which of the two amoeba is "the original one"? Without knowing that, how do we know how long it lived? I think you need to exclude viruses and bacteria and other teeny-tiny life forms because the entire concept of "lifespan" is ill-defined. SteveBaker 20:37, 3 April 2007 (UTC)
As mentioned earlier, bacteria aren't exactly the only ones with that problem either. Some species of trees form tree colonies where I believe all trees are rather interconnected. Many plants and animals (starfish) can reproduce two whole entities when split. Many culinary banana's are all apparently fruit from the same plant.
When does something become completely different? Sounds like Ship of Theseus arguments are coming about. Root4(one) 22:11, 3 April 2007 (UTC)
I don't think an ameoba qualifies as an animal in most people's definition. I was thinking high-level stuff, a 1 lb. or heavier kind of thing. Vranak

As far as trees go, I read somewhere that if a giant sequoia lives long enough to get 3 cm thick bark, it will never die unless: A it gets cut down by humans or: B it get struck by lightning. J.delanoy 02:40, 4 April 2007 (UTC)

[edit] Stem Cell Research

I'm in the middle of making a high-school presentation about Stem Cell Research, and as an introduction would like to include a ballpark estimate of how many people (in America or in the world) researchers believe can be affected by their results. I've seen sites online talk about how Alzheimer's, Parkinson's, diabetes, and organ transplants will be improved, but nothing seems to actually name numbers. Does anyone have an estimate, or an idea for how to find one? Thanks The Uglymancer 21:34, 2 April 2007 (UTC)

With the news announced today that a team in Britain managed to grow a heart valve from adult bone marrow stem cells - I'd say that anyone with any kind of a heart condition will one day benefit - that's an awful lot of people. If the dream of growing human body parts in the lab from stem cells that come from the patient himself/herself comes true - then in principle, almost everyone will one day benefit because any kind of organ failure can be fixed by replacement surgery. Right now, we can replace a lot of body parts - but the need for 'donors' is a limiting factor and the inevitable problems of rejection limit who can benefit. Parts growm from stem cells can fix those problems without rejection and without the need for a donor. SteveBaker 22:29, 2 April 2007 (UTC)
In fact stem cell research could offer to replace conception and birth of one's off-spring with indefinite longevity of one's self. Nebraska bob 02:27, 3 April 2007 (UTC)
Okay, so it might be fair to say what I was half expecting (dreading?).... that depending on the maturity of the field, it'll pretty much be an indefinably large percentage of the population... I guess I won't use a specific number then, just a description. Thanks The Uglymancer 04:22, 3 April 2007 (UTC)

[edit] Just been watching House on DVD

It's a great show but it does leave me wondering as to the medical accuracy of some of the events depicted. The titular character is supposedly a world-renowned physician and medical genius - but even so, would such a person *really* get so much leeway for his crazy-sounding, untested, sometimes unethical schemes, borderline illegal behaviour and self-confessed malpractice from The Powers That Be? In real life, he'd have been sacked and struck off the medical register a long time ago, wouldn't he? Or are there really doctors like that running around like Dirty Harry with a stethoscope, turned a blind eye to because they are good at what they do and get the results? --Kurt Shaped Box 21:56, 2 April 2007 (UTC)

I just assumed it is the same with all the ER and CSI clones (forgive me if they aren't the 1st). They'd span a spectrum, from things probably quite close to truth and events which really occurred, to completely made up rubbish that doesn't even make sense in real life. I personally dislike the shows partly for that exact reason, you may "learn" something which is complete rubbish. Vespine 22:20, 2 April 2007 (UTC)
Well, it's a TV show - we have to give it some leeway. My biggest beef with it is that things happen so insanely quickly. Patients and diseases react to treatment in minutes or at most hours - not days and weeks like in the real world. As for House's behavior - this is supposed to be a teaching hospital - and the three junior doctors who work with him are supposed to be trainees...whilst you might just conceivably be able to tolerate House's methods in a regular hospital - you certainly wouldn't want him teaching young, impressionable doctors! Also, I'd hate to see the bills his patients rack up - bazillions of scans and tests and procedures - plus 100% of FOUR doctor's attention...ouch! The important thing to know if you are one of House's understudies is: "It's NEVER Lupus."...almost every week one of them suggests it and is subsequently shot down in flames. SteveBaker 22:23, 2 April 2007 (UTC)
Operations and organ donor finding always seems to go so perfectly smoothly too. [Mαc Δαvιs] (How's my driving?) ❖ 06:28, 3 April 2007 (UTC)
Also, any major organ damage caused by the cocky, know-it-all underlings' incorrect treatments seems to magically fix itself once House has sussed out the correct diagnosis. I've lost count of how many times they've managed to destroy the patient's kidneys/liver/lungs by administering the incorrect medication (often several times) before the mighty House has his 'eureka moment' and sorts everything out in the last ten minutes of the episode. --Kurt Shaped Box 15:55, 3 April 2007 (UTC)
Four doctors who seem to be experts in just about every single medical, diagnostic and labwork procedure known to man - even those completely outside their own areas of expertise. From watching the show, sometimes you get the impression that House and his team are the only full-time employees of the hospital. ;) --Kurt Shaped Box 23:25, 2 April 2007 (UTC)
And there are no patients. I work in a hospital. Every time you turn around, there's a lost patient asking where some office is, where is the bathroom, where is the cafeteria, where can they smoke, where is doctor so and so, where is the pharmacy... House parades around the hospital and is never stopped by any of them. As for patients, every doctor in my real world hospital has 3-4 patients in a waiting room ready to be seen from the beginning of his/her shift to the end. House has one patient for days. It is like CSI in that way. The detectives have one or two cases, not a stack of 50-60 cases like real detectives. It voids the real point of such work. It isn't about the patient or the case (depending on the career), it is about knowing which ones to pay attention to and which ones to write off. It is physically impossible to handle them all. --Kainaw (talk) 01:09, 3 April 2007 (UTC)
The show is intolerably stupid, stupid, stupid. No one can behave like he does and not run into a hundred kinds of negative feedback, penalties, and barriers every hour of every day. It is difficult to find any aspect of his character that matches what most of us would consider an admirable doctor, teacher, supervisor, or partner. Twice I tried to watch it because friends said they liked it and couldn't make it past the first 20 minutes. Even the diagnostic process, that is supposedly what he is so good at, is stupidly wasteful, and "hunch-based". There is nothing impressive in that-- the master of the impressive diagnosis is impressive when he shows you a system that solves a problem that has stumped his hunches. What is the appeal of this show? alteripse 01:22, 3 April 2007 (UTC)
If youre a real doctor then Im afraid it is going to annoy you, just like any program where the viewer knows more than the writers.
I think the main appeal of the show is the central character - he *is* a pretty cool guy, a nonconformist anti-authoratarian with a healthy dose of the dark, brooding, flawed anti-hero. Like I said, Dirty Harry with a stethoscope. I bet the teens love him and his one-liners. --Kurt Shaped Box 15:45, 3 April 2007 (UTC)
To my brief viewing, he looked like a self-centered, abusive asshole with a drug problem and a personality disorder. alteripse 16:05, 3 April 2007 (UTC)
Exactly - teenage boys want to be him, teenage girls want to be with him, and fix him... ;) --Kurt Shaped Box 16:12, 3 April 2007 (UTC)
I think you are completely correct. It is interesting to think about what comprises "coolness" in popular culture. It seems to be an air of detachment from other people's needs or social rules, so that one can follow one's own impulses and gratification without being limited by conscience or normal social relationships. The problem is that people who are really like that are harmful to those around them in proportion to the coolness. Most coolness is relatively low level and at least limited by some personal response to social constraint, but all you have to do is amplify exactly the behaviors and attitudes that make a person cool and you should begin to recognize that it isn't something you want in a person from whom you need anything other than a vicarious thrill. And damn, with that recognition you have just become a grown-up... alteripse 16:35, 3 April 2007 (UTC)
WRT the 'one patient' thing, it's made pretty clear from the beginning that House is an expert in just about every area of medical science and somewhat of a legendary figure for his ability to see things that everyone else has missed - and that he only sees patients on that basis, with full 'money is no object' backing from the hospital. IIRC, it's explicitly stated that the hospital board see the presence of one of the world's most esteemed doctors on their staff as worth more to them (probably in terms of PR) than he costs them in financial terms (yes, that probably never happens in the real world either). --Kurt Shaped Box 16:11, 3 April 2007 (UTC)

I'd suggest that Scrubs is one of the more accurate medical television shows. Perhaps not so much for the medical science as for what a resident's life is like. — Knowledge Seeker দ 03:20, 3 April 2007 (UTC)

I can't stand Scrubs - it falls into the horrible trap of having someone learn a 'valuable lesson' at the end of every episode - it sickens me that they do this. "Green Wing" is my all time favorite. SteveBaker 05:34, 3 April 2007 (UTC)

Plenty of material here for On-screen clichés. Go to town, folks. JackofOz 05:55, 3 April 2007 (UTC)

House is pretty fictional. He is supposedly part of the "diagnostic medicine department" - there is no such thing in any medical establishment I know of. Hospitals don't employ doctors whose job is to take "hard cases". --Bmk 07:24, 3 April 2007 (UTC)
Although that is true for most community hospitals, many large teaching hospitals in the US have a "diagnostic clinic" for exactly that purpose. alteripse 11:09, 3 April 2007 (UTC)
So, what happens to the 'hard cases' who've stumped the other docs? --Kurt Shaped Box 15:45, 3 April 2007 (UTC)
They either eventually get diagnosed correctly by another doctor who correctly recognizes the pattern or carries out a different process, or they eventually get diagnosed correctly because new clues appear, or they eventually get misdiagnosed as something else, or they continue to get by with treatment of individual symptoms or problems, or they stop coming to doctors and the natural history plays itself out, or they die. alteripse 16:05, 3 April 2007 (UTC)

I'm pretty sick of the "rebel" cliche that seems to take over every cop show, and is now spreading to every other genre. One of the worst examples was Armageddon (film), where NASA apparently was unable to figure out how to drill a hole in the comet threatening Earth, so had to hire a dozen oil well drillers, every one of which seems to be a rebel without a clue. Aside from the dismal science ("Oh no, that comet is made of iron ferrite !") and camera changes every second (making it look like an MTV video), and cheap special effects (all they could do to show people experiencing 11 g is have them shout while they wiggled the camera), this movie gets my vote for worst of the decade. StuRat 21:42, 3 April 2007 (UTC)

TV needs a show based around a rebellious proctologist. --Kurt Shaped Box 22:12, 3 April 2007 (UTC)
Unfortunately, James Bond already has taken the name "Goldfinger". StuRat 04:46, 4 April 2007 (UTC)

I still don't get why people who watch this show idolize a character who is basically a racist, sexist bully and borderline criminal psychopath. --81.77.84.86 22:20, 3 April 2007 (UTC)

Not wishing to be annoying, but this seems to be straying off-topic into a general discussion of what people think about films and TV, which does not belong on the reference desks. There are some good answers above, but the temptation to 'express ourselves' seems to have overtaken a few. Save the desks! Keep them referencey! Skittle 22:23, 3 April 2007 (UTC)

It still seems reasonably close to the question to me. It started being about abusive, rebellious doctors on medical shows, and that was generalized into why people like abusive, rebellious characters in general. We haven't yet gotten to a discussion of Hitler, have we ? StuRat 04:50, 4 April 2007 (UTC)
Spoke too soon? --Ķĩřβȳ♥♥♥ŤįɱéØ 05:22, 4 April 2007 (UTC)
So, what do you all think about Triumph of the Will (or the description in that article)? --Bowlhover 05:26, 4 April 2007 (UTC)

The purpose of any drama show is not entirely to portray accurate situations, but dramatic ones. A real hospital would not run like the one portrayed in House, but House is very good at exploring issues and showing science that many would never witness in their lives. Many brilliant scientists don't feel the need to write a biography (may not be allowed if they work in some areas). House is fable and drama, not to be confused with fact. There are many valuable things learned, and it is fun highlighting the flaws ;) DDB 05:32, 4 April 2007 (UTC)

But couldn't the show be just as good, even better, if House was still brilliant, but worked cooperatively with others to determine tricky diagnoses ? I fear the viewers are degenerating into the Jerry Springer set, and just want the men to take their shirts off and hit each other with chairs for entertainment. StuRat 05:41, 4 April 2007 (UTC)

[edit] Vapor Pressure

Can someone please tell me what the Vapor Pressure (in torr or mmHg) is @ 16 degrees celcius? Thank you. —Preceding unsigned comment added by 76.188.176.32 (talk • contribs) 23:58, 2 April 2007

of what? water? --Spoon! 00:59, 3 April 2007 (UTC)
The equation you are looking for can be found here vapor_pressure -Czmtzc 01:07, 3 April 2007 (UTC)

[edit] flagellates

{HELP ME} how are flagellates important besides being on the food chain?

See Flagellate. The opening paragraph answers your question. --Kainaw (talk) 01:05, 3 April 2007 (UTC)