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October 21

James McCollum

Still looking for some biographical info on Canadian engineer, James K McCollum. He was the co-inventor of the Sleeve-Valve mechanism for internal combustion engines along with Scotsman, Peter Burt.

Jerry Wells, Australia.

Weve already tried to answer this question. If these links are red, its pretty pointless asking further. Why dont you Google it?--Light current 00:45, 21 October 2006 (UTC)

• http://www.nevadarockhounds.com/AWA/History/SingHist.html
• http://www.enginehistory.org/pioneering_sleeve_valve.htm --12.104.14.109 22:17, 26 October 2006 (UTC)

Page updating problems.....

I`m having a terrible time updating this page. I`m usually on AOL,,,get blocked often on account of that. I`m currantly on Mozilla but, even worse...re-fresh/update brings me to about this time, YESTERDAY! Can anyone offer some assistance? TY Dave 172.128.242.194 02:33, 21 October 2006 (UTC)

Simply creating an account would help. This would also make it easier for us to diagnose your problems by referring to your edit history.--Shantavira 08:53, 21 October 2006 (UTC)

Reading Wikipedia:Advice to AOL users would be a good idea =) --`/aksha 12:27, 21 October 2006 (UTC)

Phase-determination pressure

Is the pressure on a phase diagram the vapor pressure of the substance in question, or is it the total pressure of the substance's environment? It seems to be vapor pressure when discussing the equilibrium between liquid and gas, but it seems to be total pressure when discussing the pure phases (e.g., the diamond/graphite transition). Which is it, or is it some third possibility? --Tardis 02:43, 21 October 2006 (UTC)

It's the external pressure applied, i.e., if you put the substance in a rigid container with a movable piston and apply some pressure to the piston, the phase diagram tells you the phase the subtance will take. It's only equal to the vapor pressure when the gas in equilibrium with another phase. For example, say the temperature is between that of the triple point and the critical point. If the applied pressure is less than the vapor pressure at that temperature, the substance will be completely gaseous. As the pressure is increased, the volume decreases slowly, until the pressure reaches the vapor pressure and the gas begins condensing into a liquid. At this point the piston suddenly slides in without resistance, because the gas condenses into a liquid and the volume changes while the pressure remains at the vapor pressure (moving the piston does no work because dp = 0). Then when the substance is completely liquified, the pressure begins to increase again, now greater than the vapor pressure. —Keenan Pepper 18:25, 21 October 2006 (UTC)

This is all from Atkins' Physical Chemistry, ISBN 0-7167-8759-8. —Keenan Pepper 18:28, 21 October 2006 (UTC)

Cheese longevity

I buy packages of shredded cheddar cheese in a sealed zippable bag (as in, initially properly sealed and re-sealable). The bag claims that it should be refrigerated, of course, and finished within "3-5 days" of opening. However, I use only a little at a time and so have seen it last much longer than that in an arid environment without any apparent ill effects. Just how long should I expect it to be safely edible, and what would be the first sign that it's not? --Tardis 03:12, 21 October 2006 (UTC)

The first sign will be visible specs of mold. How long they take to develop depends mainly on how sterile you keep it when it is opened. If you reach a grubby hand down in the bag, you will likely heavily contaminate it. If you open it upside down, so nothing can fall in, then let some cheese out and quickly reseal it, then drive the air out, you might get lucky and not have any bacteria in there that like cheese. Another suggestion, buy smaller bags or divide your bag up into single use bags, then freeze each until ready to use. StuRat 03:28, 21 October 2006 (UTC)

no way dude, what's-his-face (keenan pepper???)'s friend worked in the cheese industry!! Wait for his repesonse.

No whey ! :-) StuRat 11:57, 21 October 2006 (UTC)

Ive heard cheesy jokes before 8-(, but that on just about takes the biscuit. 8-)--Light current 17:12, 21 October 2006 (UTC)

I have no idea who you're talking about. —Keenan Pepper 17:53, 21 October 2006 (UTC)

Sorry I cant see the joke here 8-(--Light current 19:27, 21 October 2006 (UTC)

The cleanliness of the processing and packaging have a large effect on the longevity of shredded cheese, which is inherently shorter than that of a wheel or wedge of cheese. If the cheese gets moldy quickly, and you are sure you did not contaminate it, you might just wonder "Who cut the cheese?"Edison 21:52, 21 October 2006 (UTC)

Yes, the much greater surface area of shredded cheese allows it all to get moldy, as opposed to just the surface of a large chunk of cheese. StuRat 00:20, 23 October 2006 (UTC)

Whistling sine waves

A whistling sound is pretty close to a sine wave. Why? What are the processes behind the sound in whistles that make it like that? I understand the mouth and lips work as a resonant chamber, but why, exactly, no timbres are produced? Our article on whistling mentions this fact, but doesn't give any explanation. ☢ Ҡi∊ff⌇↯ 05:59, 21 October 2006 (UTC)

The mouth and the lips form a high Q resonant chamber. Look at resonance and Q factor. The Q is so high that it filters out frequencies higher and lower than the one you are whistling leaving essentailly only one frequency. This one frequency must be a sine wave. 8-0--Light current 07:31, 21 October 2006 (UTC)

Ah, I've never thought about it like that. Makes sense. Thanks for the explanation. :) ☢ Ҡi∊ff⌇↯ 07:54, 21 October 2006 (UTC)

Light Current, are you sure about your explanation? The Q factor of, say, a woodwind instrument is probably higher than that of the mouth cavity, and they do have a tone that is clearly not sinoidal. After all, also a high-Q resonator gets higher harmonics excited alongside of the fundamental, and the amplitude of the harmonics (in units of the fundamental's amplitude) is what defines the tone or timbre. What a high Q factor rids you of is line broadening, but it does not enforce a pure sine. By the way, Kieff initially asks about whistles and Light Current talk about whistling without a whistle. So, of which one do you two now claim that they had an extraordinary pure sine? I doubt both, actually, but as we all three probably have a microphone input bin our computers, we can easily check. Simon A. 22:43, 21 October 2006 (UTC)

Well the very fact that woodwind instruments have a certain timbre proves that the instrument Q is much less than your mouth/lip system. --Light current 23:11, 21 October 2006 (UTC)

No, Simon, I was actually talking about whistling with the mouth (that's why I wikilinked to whistling instead of whistle.) The reason I asked is that I've already recorded myself whistling and looked at the wave, and it's very close to a sine wave. ☢ Ҡi∊ff⌇↯ 10:36, 23 October 2006 (UTC)

IIRC, the difference between whistling and the sound of a woodwind instrument is that the woodwind instrument has a vibrating reed that produces a range of harmonics, whereas whistling is highly filtered noise (caused by air turbulence). Whistling is unvoiced whereas the woodwind is "voiced" in the way that it is analogous to a vibrating vocal fold.

So whilsting is just noise filtered drastically to single out an individual harmonic. There is of course a bit of noise in the "signal" too, since our mouths aren't perfect. Magic Window 17:31, 24 October 2006 (UTC)

COSTAS loop

In costas loop, the phase of generated carrier must be such that it matches with that of Incomimg carrier so that angle phi is zero.But why is the error signal given to the Voltage Controlled Oscillator instead of a phase shifter???

What do you mean by phase controller? THe freq and phase of the VCO is controlled by the vco i/p voltage

--Light current 09:02, 21 October 2006 (UTC)

Transmission line theory

We all learn that circuits have a fixed value of resistance,capacitance and inductance.But why sudden change in theory when it comes to transmission lines with topis such as reflectivity?Any lucid and simple explaination?

In transmission lines, resistance, capacitance and inductance are still there, but the elements are not lumped. THey are distributed over the length of the line. Any discrete lumped RLC cct (like ther ones youre used to) will also have parameters like input match, reflection coefficient etc. but at low frequencies, these parameters do not matter so much as they do at high freuencies where transmission lines are commonly used.--Light current 09:08, 21 October 2006 (UTC)

I'm not sure who taught you that circuits have a "fixed value" of resistance, capacitance, and inductance, but its usually not true. For example, the resistance of a typical physical resistor changes noticeably depending on the temperature. Variable capacitors can be constructed by using moving plates. Also active circuit elements like transistors and diodes are typically nonlinear -- that means the resistance and capacitance vary depending on the applied voltages or currents. In fact a reverse-biased diode is often a more economic way to form a variable capacitor than a physically moving device. We normally just approximate these circuits as linear circuits, with localized values of the elements, determined at some moment of time, because then we can calclulate the behavior. Our article Electrical network touches on this in the section on Piecewise-linear approximation, but I can't say the discussion is complete enough to give a good understanding. -- The Photon 22:38, 21 October 2006 (UTC)

I dont think the questioner was really asking about nonlinear circuits but just the diff between the circuit theory and em field theory approaches.--Light current 23:01, 21 October 2006 (UTC)

has to do with frequency and size of the components. Lumped is easier to analyze. But consider this: You have a generator with an impedance and a fixed resistive load. If the resistive load is far from the generator and the impedance is changed far from the generator, how does it know? there is a lag in that information. The answer is that the generator sends out a fixed power value and what cannot be aborbed is returned as a reflection. As the frequency increases, that distance is made smaller and smaller until it makes it difficult to speak in terms of voltage and current and the preferrred parameter is power (S parameters). The bottom line is that the source has no idea what the load is until the power is reflected back. Lumped analysis is adequate when the dimension of the circuit far exceed the wavelength. --Tbeatty 07:33, 22 October 2006 (UTC)

Reality

I present two situations.During the genesis of time, the universal laws of reality came into being:-

1)The Domain of these laws started spreading at the speed of light(max speed limit) across this current diemension after the beginning of the big bang and that the universe is not defined in the domain beyond this hypothetical diemension.

2)The domain of these laws were applicable instantaneously across the whole diemension once the universe was created.

Which of the above is correct??

Given that information cannot travel faster than the speed of light, the only way for us to arbitrate between them (ie going past the universe "horizon" and doing some experiments) is impossible. Hence the question is, in a very fundamental sense, totally unanswerable. Batmanand | Talk 16:40, 21 October 2006 (UTC)

Can you equate information with laws? If laws are instead properties of space, then (2) seems to me to be right. Clarityfiend 21:55, 21 October 2006 (UTC)

The big bang theory gets around this whole question by saying that at the beginning of time, the spacelike diameter of spacetime was infinitesimally small. This means: before time, there also was no space. At te big bang, time and space spread out together. The spreading of time and space was, by the way, not limited by the speed of light, as this limitation applies to motion within spacetime, not to the expansion of spacetime itself. Maybe we have articles on the flatness problem and on cosmic inflation which explain more. This stuff is, however, quite difficult to grasp. Simon A. 22:47, 21 October 2006 (UTC)

But the expansion of spacetime isn't the issue here, he's asking about the expansion of constants within the domain of spacetime. Whether spacetime was inconceivably small or 50% as big as it is now, if the laws were to substantiate after spacetime itself came into existance, size and distance doesn't seem to logically be a factor. On a hunch I'd reject both options, going instead for a neater "the laws came into existance the same instant that space time did" style argument.  freshofftheufoΓΛĿЌ  04:46, 22 October 2006 (UTC)

I think what he's trying to say is that when the universe was scrunched up infintesimally small, any fluctuations in what we now think of as constants had the opportunity to settle down to some kind of average value, and then when the universe expanded it carried those average values out. Or something like that. Confusing Manifestation 09:50, 22 October 2006 (UTC)

Can you have fluctuations in an infinitely small space?  freshofftheufoΓΛĿЌ  12:42, 27 October 2006 (UTC)

Ic 8038 and Ic 555

Both Ic555 and Ic8038 can be used as free running oscillators.Then why have both of them???

8038 can generate triangle, sine and square [1]. 555 can only generate pulse waveforms [2]--Light current 09:11, 21 October 2006 (UTC)

And the 555 is cheaper (and older). And it even has a Wikipedia article: 555 timer IC Simon A. 22:53, 21 October 2006 (UTC)

SATA computer

I purchased a laptop computer with an SATA hard disk + XP Home Edition. I want to install my previous copy of XP Pro on it but failed (my last computer was dead so it's legal to transfer the XP to my new laptop). The XP installer could not see my Compaq Presario's SATA hard disk. How do I solve this problem? -- Toytoy 14:15, 21 October 2006 (UTC)

Legal may be, but difficult, as you will have already 'activated' the operating system om your old computer and it may not activate on the new one.

You dont say the make of the 2 computers. Is it possible that you had a special version of XP Pro that was designed for (and only recognises) your old computers hardware?--Light current 14:21, 21 October 2006 (UTC)

Have you downloaded the latest XP SP and SATA drivers? When you say it doesnt see it you mean it doesnt detect it at all ? Sounds duff. Try another SATA port, different drive, different lead, etc. By the way, youre in the wrong section mmatt 15:03, 21 October 2006 (UTC)

My XP is a site licensed copy. At lest in theory, I can install it on a new computer even multiple computers. -- Toytoy 15:10, 21 October 2006 (UTC)

It sounds like you have a crippled version of XP Pro that will only install on the computer it was sold with. You need a generic version of XP Pro that will install on any computer - then hope your product key works with it. --Kainaw ^(talk) 16:42, 21 October 2006 (UTC)

Put the drivers for the SATA disk on a floppy disk and press F6 during install when it says to do so at the bottom. This way you can install SATA/RAID drivers for the disk that Windows will be installed on. - Dammit 16:45, 21 October 2006 (UTC)

Youngs experiment

In Youngs experiment, why doesnt the wavefunction collapse when it happens on one of the two slits? Whats the difference between the slit and the detector from the photons point of view ? How do you detect a single photon anyway ? Also, if you slightly offset the light source from the centre point between the two slits, would you able to detect which slit it went through depending on the time it took to reach the detector. The problem with this experiment is that its so simple you feel you should be able to outsmart it ! mmatt 14:41, 21 October 2006 (UTC)

Have you read double-slit experiment? What do you mean by "outsmart it"? There's nothing to outsmart. As for detecting a photon - your eyes do it all the time. So do cameras. There are many forms of photon detectors. From the photon's point of view, the slit is an opening to pass through. The detector is a dead-end that it slams into at the speed of light. --Kainaw ^(talk) 16:41, 21 October 2006 (UTC)

Wait a minute, a lot of the photons do slam into the walls around the slits, don't they? Still, some slip through and give the double-slit effect. —Bromskloss 17:09, 21 October 2006 (UTC)

By outsmart it I mean that that you feel as if you should be able to somehow infer which slit it went through, but of course you cant. Its a trick of the mind, I know.

How do you detect a single photon? I know it can be done, but how? The eye detects lots of photons, not just one. I dont want to get hung up on this, its not really relevant to the main question.

Are the photons that get cleanly through the slit the only ones that contribute to the effect? I always thought they scattered off the edges, thats how they change direction backwards to contribute to the effect, otherwise you would just get a very narrow band directly in the line-of-site from the light source ? mmatt 19:04, 21 October 2006 (UTC)

The eye can detect a single photon! From Rod cell:

A rod cell is sensitive enough to respond to a single photon of light, and is about 100 times more sensitive to a single photon than cones.

As for the scattering you mention, I don't want to say too much because I'm not absolutely sure, but you seem to view the photon as a particle, rather than a wave. A wave spreads out after a small passage. Think of waves on the surface of water. —Bromskloss 20:53, 21 October 2006 (UTC)

Isnt it a particle and a wave ? matt

It's not that we can't detect a single photon, it's that we can't EMIT a single photon. However, we CAN emit a single electron, and detect this. Watch, as the electron experiences the exact same wave-particle duality, pushing the relevance of this experiment into the macroscopic world. :) 81.93.102.3 19:36, 21 October 2006 (UTC)

but the question still applies to electrons, right ? You have to get some scatter off the grating/slit or the electrons/photons shoot off in the wrong direction to interfere ? So if they interact with the slit in this way, why doesnt the slit ( or the sides of the slit ) collapse the wavefunction ? mmatt

Even before reaching the slits, they pass air molecules without collapsing. (Well, I guess some may collapse, but not all.) —Bromskloss 20:58, 21 October 2006 (UTC)

Right. I though about that, but I thought that because an air molecule is so small, you wouldnt collapse the wave function - you would have a superposition of two possible paths one of which involved collision with an air molecule. But with the slit ( or the sides of the split ), which is macroscopic, the wavefunction would collapse mmatt 21:09, 21 October 2006 (UTC)

Hub Gears Wont Change

I had to remove the black thing that controls my gears in order to tighten a loose nut for the wheel. When I removed the black thing (that covers the nut through which some pin things protrude), the pins came out quite far. Now that I put back the covering, having tightened the nut; a) the gears don't change (no matter where I push the gear lever on the handlebars) and it's stuck in some lowish gear and

b) the gear lever on the handlebar wont push into 6th or 7th gear.

Can anyone diagnose the problem and suggest a solution? The manufacture is 'Sachs' but this was insufficient to draw useful information for me to fix my bike. --Username132 (talk) 15:00, 21 October 2006 (UTC)

I take it that you are talking about a bicycle with derailleur gears, right?

I also assume that it is a standard modern gear shift. Mounting these is not that difficult but also far from trivial. First check by comparing with a working bike that you have remounted the derailleur correctly. Make sure that both its springs operates in the correct way: there is one spring inside the parallelogram shaped lever that moves the derailleurs two little cogwheels over the gears. This spring pulls the derailelleur over the highest gear (i.e. smallest gearwheel) and if you pull with the Bowden cable against this spring, you switch down to lower gears. That your stuck in a low gear seems to indicate that ever the Bowden cable is too tight or the sping is blocked or the derailleur is mounted the wrong way. There is also a chapter on derailleur adjustment in the Wikibook on Bicycle repair. Reading it might be a good idea. Simon A. 23:08, 21 October 2006 (UTC)

Ok, stupid me, I overlooked that your heading explicitly sais that you are talking about hub gears. These were always a bit of a mystery to me, so I don't have a better suggestion than checking that the Bowden cable is ok. Simon A. 23:10, 21 October 2006 (UTC)

Now, I got interested in hub gears and had a look at the German Wikipedia, which explains quite a lot in its article de:Nabenschaltung. There, you find the hint that before disassembling a rear wheel you should switch to that gear that relaxes all the springs in the hub, i.e. the one where the Bowden cable is not under tension (and the little chain nearly all the way in I suppose). If you want to adjust the gearshift, you have to set the switch at the handlebar to a gear certain setting and the hub gear itself to the same gear (by pulling at the little chain I suppose). They give a table which gear to use for adjustments for different makes. (How many gears do you have, and how old is the bike? That should be sufficient to identify the model.) Then, there should be a little bolt that allows to finetune the length of the cable in order to match hub gear and handlebar switch markings. Simon A. 23:56, 21 October 2006 (UTC)

I fixed it by pushing the pin in until it stopped. The "Schaltbox" has the manufacturer 'Sachs' and 'super 7' written on it (it's a 7-gear bike). I don't know the age, cause I bought it second hand but I'd guess that it was made in the last five, maybe even three years. Username132 (talk) 14:09, 22 October 2006 (UTC)

Congrats for solving the proble. By the way, Fichtel & Sachs has been bought be SRAM a couple of years ago, and on their website you find a link Techical Documents with a manual for a "SRAM S7 hub gear". Maybe that's yours, or at least its successor model? Check it out here. Simon A. 09:44, 23 October 2006 (UTC)

Thanks, that's perfect! --Username132 (talk) 16:13, 23 October 2006 (UTC)

Atheroma

We were always told this was fatty deposits. Our article says it is other sorts of debris. Which is it and if its not fatty, why should we stop eating fatty food?--Light current 16:45, 21 October 2006 (UTC)

So you die later instead of earlier. - Nunh-huh 17:24, 21 October 2006 (UTC)

New Iraq strategy: open a chain of fast food restaurants selling triple cheeseburgers, all the fries you can eat. Clarityfiend 17:37, 21 October 2006 (UTC)

Thirty years ago, the diet police were hating on animal-fat based butter, and proclaimed transfat-based margarine to be healthy. That's why my grandma only uses margarine, hehe. It has flipped around, with transfat being bad too. Then fat was generally bad. But mostly it was saturated fat... but also unsaturated too, except for olive oil, and rapeseed. There was the anti-sugar craze, and the idea that carbohydrates were what really got us fat, not fat. Maybe we should detox or go raw, or vegetarian at least. Organic? Cereal used to be great for you, but it has too much sugar. We don't get enough vitamins and minerals. Ah, chloresterol is what causes heartattacks now, not fat. Heavy metals concentrate in fish. The Cato Institute published an article: As Taubes pointed out in his article, the simplistic notion that dietary fat is bad was a political and business judgment, not a scientific one. Despite ambiguous science, in 1977 a Senate committee led by Sen. George McGovern issued a report advising Americans to consume less fat to avoid "killer diseases" supposedly sweeping the country. The politically dutiful National Institutes of Health soon joined the anti-fat bandwagon, a move that spawned the low-fat food industry. What exactly is the basis for trusting the food alarmists again? The best way I believe is to read the journals yourself, not watch the news. The news will tell you that french fries and breastmilk cause cancer. Remember those days? Atherosclerosis is caused soley due to LDL and VLDL cholesterol, according to every single source I have heard in the mainstream media—even though macrophages, and calcification have quite major roles. I bet the media pushes the chloresterol part because it is scary, and there is someone to blame. What you eat is partially based on your decision—some foods have more or less cholesterol. You don't decide if macrophages or ossification will obstruct or harden your arteries, but you can be to blame for eating yourslef to death.X [Mac Davis] (SUPERDESK|Help me improve) 00:12, 22 October 2006 (UTC)

Here's another free bit of advice: don't get your dietary recommendations from teenagers, and don't get your understanding of the pathogenesis of atherosclerosis from them, either. - Nunh-huh 05:24, 22 October 2006 (UTC)

How can we tell whos a teenager? Most people here act like one (including me) 8-)--Light current 14:08, 22 October 2006 (UTC)

Excellent work from mac davis! I think a lot of the confusion with health is disinformation in the media. they take a "phase 1" study of about 30 people and tout it immediatly as fact just to fill in column inches (or webspace) the result for us is now complete confusion and having to use the wikipedia reference desk and wikipedia to seperate fact from fiction! chocolate helps your heart This one from the BBC is a good example, so now I think "hey maybe a bit of chocolate is good for you" and its a headline based on 20 people!!!

Sauropod size

I'm trying to write a book on the largest sauropods. The technical information like the discovery, etc., is easy. However, it's the size that continues to differ. Various references such as different books and websites give different statistics. My main sources are EnchantedLearning.com, DinoRuss' Lair, Wikipedia itself, and the DinoArchive and a few of my own calculations. As you can see below, the estimates vary considerably.

1. Argentinosaurus: 22-45 m, 60-100 tons 2. Paralititan: 20-32 m, 60-80 tons 3. Seismosaurus : 30-54 m, 25-150 tons 4. Supersaurus : 24-45 m, 30-100 tons 5. Bruhathkayosaurus: 28-44 m, 150-220 tons 6. Amphicoelias: 37-62 m, 50-170 tons 7. Brachiosaurus: 21-30 m, 15-80 tons 9. Argyosaurus: 20-40 m, 45-80+ tons 10.Ultrasauros: 25-35 m, 40-180 tons

As you can see, the variation is not negligible. I am also aware that these creatures are known for very little fossil evidence. If you can,please suggest corrections for this table (taking into account that these creatures are known for very little fossil evidence). I appreciate the help.

You're using Wikipedia as a source? It's very unrealiable. I suggest using books as your main source, instead of websites.

As for the question, I think it's better to include the range of size estimates in your book. But if you really need to come up with a single figure, try taking the more reliable size/weight estimates and averaging them, while noting in your book that estimates vary wildly. --Bowlhover 19:47, 21 October 2006 (UTC)

What does KIBRA stand for?

Kibra is the name of a gene associated with memory performance in humans. Kibra sounds interesting and exotic. What is the origin of this name? It is an acronym? Tavilis 18:40, 21 October 2006 (UTC)

Sounds like it is is short for kidney and brain MeltBanana 23:07, 21 October 2006 (UTC)

Surfaces and bonding

Suppose you got a block of some metal, say gold, and cut it with a sharp blade in a good vacuum, so the cut surfaces had no gases adsorbed on then. Then you pressed the two cut surfaces back together. Would they stick together? Would the cut disappear and the metal become one solid block again? If not, why not?

Also, same question for a network covalent solid, like diamond. Would the cut surface be covered with dangling bonds (unpaired electrons)? Would the cut surfaces attract each other and stick?

Any good books about this stuff? —Keenan Pepper 19:14, 21 October 2006 (UTC)

Yes, I think cut metal parts would fuse together. How would you cut diamond neatly? Diamonds dont stick together for some reason unknown to me. Try welding diamonds!--Light current 19:31, 21 October 2006 (UTC)

What you described with metals is called a cold weld, and you can even do it with two different metals. I don't think it would work with diamonds unless you had an extremely high pressure and temperature to reform the bonds, however. StuRat 20:12, 21 October 2006 (UTC)

Yeah thats what I was trying to say. I suppose it must be possible with diamond given enough temp and pressure as Sturat says. After all, we are told that diamond only forms under condtions of extreme temperature and pressure.--Light current 20:21, 21 October 2006 (UTC)

Thanks, cold weld and asperities (once I figured out the latter was misspelled in the article =P) are much better strings to search for. I don't understand why you say a network covalent solid wouldn't do the same thing, though. There are dangling bonds and no adsorbed gases... why wouldn't they stick together? —Keenan Pepper 23:00, 21 October 2006 (UTC)

I would assume the 'dangling bonds' of the network covalent diamond would just form bonds across the surface. So one 'dangling bond' forming a proper bond with another 'dangling bond' that you've just cut. Meaning when you stick the two pieces together, the 'dangling bonds' won't be dangling anymore. So instead of having one piece of diamond with a cut through it, you'll end up with two discrete pieces of diamond that won't bond with each other. --`/aksha 02:34, 22 October 2006 (UTC)

It seems some of the surface atoms do move and form pi bonds (a process called reconstruction), but the most stable environment for an atom is inside the crystal, so there is still an unavoidable surface energy. —Keenan Pepper 20:48, 22 October 2006 (UTC)

Zero-point energy and substance compatabilty.

I have read on one of the sites on NASA that they want to use Zero-point energy equilibrium state distruptions, It claims that ZPE is almost like atmospheric pressure, and making changes in its density or distribution might move objects. But how can this be if it is EM and some objects are not effected by EM? Are there any kinds of materials ZPE cannot effect? physicsmoron

Could you at least link to the NASA page so we know what you're talking about? —Keenan Pepper 23:17, 21 October 2006 (UTC)

That is rather speculative. I suggest Casimir effect. I do not believe any objects could be unaffected by the Casimir effect. X [Mac Davis] (SUPERDESK|Help me improve) 00:21, 22 October 2006 (UTC)

General Relativity

While researching General Relativity, a broad range of theories, mathematic equations, and list of related topics come up. I need to create a project on BASIC ideas of general relativity on a ninth grade level and am wondering what should I include. I'm planning on including Einstien, Gravity, Wormhole, Black holes, and the unification of Special Relativity. Are there any aspects of General Relativity that I am missing that can be explained in layman's terms and pictures? Am I including things that I should not be? Thanks in advance for your speedy replies. I am thankful to have this resource. 72.77.122.83 21:51, 21 October 2006 (UTC) BeBe2

I don't know if I'd include wormholes. They're strictly hypothetical and certainly not a central part of relativity. Clarityfiend 22:02, 21 October 2006 (UTC)

I wouldn't give 9th graders any of the math involved. I would include the theory that gravity works like a sheet of rubber, where if you have a small marble and a baseball on it, they would go toward each other, but the small marble will go toward the baseball more. Gravity wells, which do include blackholes/wormholes. How we orbit the sun, and how satelites are launched to stay in orbit. How gyroscopes work and how they're used for navigation (I never understood that back in high school myself). These are really the ones I would include for 9th graders. How long does this have to be? --Wirbelwindヴィルヴェルヴィント (talk) 22:47, 21 October 2006 (UTC)

Well, I have to be able to disply it on a flat poster board with pictures and captions. 72.77.122.83 23:27, 21 October 2006 (UTC) BeBe2

I like the research topic. Organizationally, special relativity was developed first, and does not include gravity. It is mathematically fairly simple (compared to other topics), and may be accessible to someone with knowledge of algebra (books like Wheeler and Taylor's Spacetime physics assume a knowledge of about algebra 2). The idea is if you assume two things, some interesting results can be shown. For more on this, see Introduction to special relativity, Postulates of special relativity, and (if you're daring) special relativity. One of the results of this work was to show that the distance (as we ordinarily measure it) is not fixed between two points in space. You might see two things one meter apart, while I see them occur two meters apart.

Gravity, in the pre-relatavistic (called "Newtonian") system, depends on the distance between two objects. For instance, the sun is gravitationally far more attractive than the earth, but we feel the earth considerably more since we are closer to it. But in the relatavistic framework, distance is not fixed between two objects... So dealing with gravity becomes a challenge. General relativity deals with gravitation, and is mathematically quite complicated (requiring college level mathematics). Gravity, under general relativity, is not a force but bending of space. An analogy is riding in an elevator: you feel heavier as the elevator starts moving up. You might (if you had never been in an elevator before) think that you're sitting still and gravity had changed to make you heavier. Equivelently, as I sit in my chair, I don't see myself speeding up (just as you don't see any difference in the elevator), however I am, for the purposes of relativistic calculations, being moved in bent space. See Introduction to general relativity.

Black holes form when enough mass gets packed together that nothing can escape from it. It is a consequence of general relativity, and observations seem to support their existence. Wormholes are somewhat more theoretical, in the sense that they are not observed to exist. Hope this helps, --TeaDrinker 23:59, 21 October 2006 (UTC)

Quantum mechanics? wave theory?

I have been reading a book on quantum mechanics - and I found one section confusing. I hope that I can phrase the question clearly.

When a series of electrons are sent through a slit - then the resulting pattern formed is a wave. The probability that a particular electron lands at any position on the wave is given by the square of the amplitude of the wave.

My question- Why square the amplitude? (I think this is what is happening -see the Wikipedia article "Normalisable wavefunction" )- I know that squaring makes the mathematics more convenient (gets rid of negatives and also gives a convenient sum of 1 when squaring components sine and cosine)But I'm still left with the basic question - why the square?

any help will be very interesting to me

We know that the probability is a real number between 0 and 1. We can observe, say by doing a one-slit experiment, that the probability doesn't have any phase information itself. Yet we also observe the diffraction occurring in the two-slit experiment. Therefore we (well, some very smart physicists like Schrödinger) invent a model that can predict the results of the two-slit and other experiments. For convenience, we express this model in terms of complex numbers inside the unit circle, which can carry phase information, but when multiplied by their complex conjugates always give a real number between 0 and 1.

So the answer is not that there is a reason to square the wavefunction value to get the probability, but that the wave function was invented as a complex number with magnitude equal to the sqare root of the probability in order to explain and predict the experimental observations. -- The Photon 22:25, 21 October 2006 (UTC)

Also note that a wave function whose interpretation is the probability of finding a particle at a particular position would not be a correct model of the observed phenomenon — not if we model the combined effect of two waves using superposition, as we normally do. Since probability is a value between 0 and 1, you will never have destructive interference in the model, which is inconsistent with observations. --71.246.5.19 13:38, 22 October 2006 (UTC)

G Protein Coupled Receptors

Does anybody have any thoughts on how many GPCRs there are in the human genome? I've read papers that give values of 750, 900, >1000. What's the latest, or most accepted value I should use?

Thanks very much for your help.

Aaadddaaammm 23:38, 21 October 2006 (UTC)

According to this recent article, "the family of G protein–coupled receptors (GPCRs), which in man contains about 791 proteins". --JWSchmidt 23:52, 22 October 2006 (UTC)

October 22

Craneflies - how have these really crappy insects continued to survive?

I mean, c'mon - the cranefly has got to be the worst-designed insect in all of creation. It's big, slow, mindless, fragile, has no method of defending itself from predators (despite being big and meaty) and is a terrible flier. Every year when they hatch, everything that eats insects feasts upon them. If God exists, the cranefly was either created on one of his off-days, or was some strange practical joke. If reincarnation is real, the people who've really been bad in this life must come back as craneflies as punishment. Seriously, how has this stupid, pointless, annoying creature managed to avoid extinction? --Kurt Shaped Box 01:39, 22 October 2006 (UTC)

There's many of them. ☢ Ҡi∊ff⌇↯ 02:05, 22 October 2006 (UTC)

"It's big, slow, mindless, fragile," - as oppossed to the...uh....intelligent-minded insects? =) I guess god really does have off-days after all, because i always thought humans were god's "strange practical joke". --`/aksha 02:30, 22 October 2006 (UTC)

Most insects at least try to escape if you go for them. I could walk up to a cranefly and slowly squash it with my finger and it wouldn't even see me coming. --Kurt Shaped Box 02:35, 22 October 2006 (UTC)

Probably insane mating. Lovebugs same thing. But these taste bad. They also more importantly taste bad to birds.X [Mac Davis] (SUPERDESK|Help me improve) 03:32, 22 October 2006 (UTC)

I wonder if the fact that they don't try to escape makes the females easier to mate with? God I feel dirty thinking like that.  freshofftheufoΓΛĿЌ  05:06, 22 October 2006 (UTC)

There are a lot of different techniques an organism can use to survive extinction. High fecundity is one of the more common ones. Not to mention, it is impossible to see these things when they aren't flying (camouflage). They are also of very little nutritional value, and it would be a waste of time for an animal to specialise. They only leave the ground once a year to mate, the rest of the time they are larvae. As long as enough mate to regenerate the population (and that wouldn't take much, I assume one female can make thousands of eggs), they will not become extinct. Simple! :) --liquidGhoul 05:20, 22 October 2006 (UTC)

Add to that a high agility that makes it possible to escape attackers and what do you get? The bloody mosquito. The reason it's not extinct is not for lack of us trying. Rarely has mankind been so united as in its efforts to exterminate mosquitoes. And they still thrive. DirkvdM 09:39, 22 October 2006 (UTC)

(reading the cranefly article) "However, it is very easy to accidentally break off their delicate legs when catching them, even without direct contact. This may help them to evade the birds who pursue them as prey." well, there's (part of) your answer. They sacrifice their own legs to survive. I guess they don't exactly need legs to mate and reproduce... --`/aksha 12:39, 22 October 2006 (UTC)

Meaning of TY1CL1

As an example "TT-P-95 TY1CL1 - PAINT,RUBBER", can someone tell me what "TY1CL1" means please? I see it in the title of numerous products.

Thanks

John

Chest rash?

I understand that this question should be directed to a dermatologist, however I just wanted to get a sense of whether or not that would even be necessary. The below pictured rashes (?) in the middle of my chest appeared about three months ago. There are approximately 25 white circular rashes, the largest about a centimeter in diameter, between my pectoral muscles. They are more defined than the resolution of the picture allows. They are not painful, itchy, nor can I feel them at all. They do not protrude from the skin. Does anyone have any idea what they might be? Cduffner 03:58, 22 October 2006 (UTC)

Have you been tanning? If so, they could be old scars. My various deep scars (from multiple motorcycle accidents, getting shot twice, and stabbed once) do not tan. The surface ones - like scratches and such - do eventually tan over. I have similar circles on the back of my right hand from gravel in one accident that do not protrude, itch, or hurt. When I tan, they stay white while the rest of my hand turns red (note, I tan red, not brown). There are a few spots that I don't remember getting scars and I only see when I tan. I was told about two of my left fingers - burned by an iron when I was a toddler. But, I assume that I had some injury long before my memory kicked in. --Kainaw ^(talk) 04:47, 22 October 2006 (UTC)

Hard to tell from the picture. Could be vitiligo. A dermatologist could tell you. - Nunh-huh 05:24, 22 October 2006 (UTC)

Could it really be vitiligo? It doesn't affect any other area of my skin, however I know my grandfather had it. It couldn't be condyloma lata, could it? I'll try to get a clearer picture. Thanks for everyone's help. User:Cduffner 05:35, 22 October 2006 (UTC)

Vitiligo can be limited to one or a few areas. As for condylomata lata - no. - Nunh-huh 05:48, 22 October 2006 (UTC)

Maybe they're just blemishes that have always been there. Your chest is usually covered by clothes, so you would be less likely to notice them, and very few people examine their own chest closely on a regular basis. I remember the day I discovered the freckles on my shoulders that had been there my entire life. I thought it was specks of dirt! XD

Blemish is no more specific an answer than "spots" although in an advertising context it is always code for acne. Freckles are usually not present at birth and can appear any time throughout childhood. alteripse 13:13, 22 October 2006 (UTC)

Not vitiligo. Might be tinea. alteripse 13:13, 22 October 2006 (UTC)

Maybe some birth mark you haven't noticed until now???BlueLighter 14:15, 22 October 2006 (UTC)

Thanks alot, you've all been a great source of information and help. I figure I better just go and ask a dermatologist to be safe. --Cduffner

THis looks a very fuzzy picture. Its not a still from the Alien autopsy film is it?--Light current 17:57, 22 October 2006 (UTC)

So will you report back to us and award a prize to whichever answer was closest? alteripse 21:47, 22 October 2006 (UTC)

Then let me quickly get my prize-winning entry in: paucibacillary Hansen's disease.  --Lambiam^Talk 22:23, 22 October 2006 (UTC)

UPDATE: Turns out it's a fungal infection. Treatment? Apply medicated dandruff shampoo (i.e. Selsun Blue) on the affected area daily for 2-3 weeks. I probably got it from the pool. Thanks guys. --Cduffner

Told ya. But what amazes me is how you got in to see a dermatologist that fast. What is your secret? alteripse 23:13, 22 October 2006 (UTC)

My secret? Have a father who's a dermatologist. :D --Cduffner

Why on earth didn't you ask him first? Also wonder how Kainaw found himself shot and stabbed? --Username132 (talk) 13:50, 17 December 2006 (UTC)

BONDING IN SOLIDS

Explain the forces between two interacting atoms when they are brought nearer to form a molecule

Start with atom and molecule, they link to other articles that explain things in even greater detail. Weregerbil 07:00, 22 October 2006 (UTC)

There are many types of chemical bonds. See that link for details. StuRat 09:57, 22 October 2006 (UTC)

Molecules are formed by Covalent bonds, you should also take a look at that article. --`/aksha 12:26, 22 October 2006 (UTC)

Software Radio

In software radio,How is it posible to diffrentiate between noise and actual modulated signal???

Unless you have a copy of the message being sent or accutaely know its statistics (same thing really), it is not possible. That is the fundamental problem of communications. If you do have a copy, then no information is being sent! 8-)--Light current 13:39, 22 October 2006 (UTC)

would enough negative charge from other sources such as pions, down quarks etc react with normal matter?

would the negative charge from pions, downquarks etc , if controlled in sufficient amounts have the same effect as the negative charges that repel electrons from each other? and if so would the reaction be more powerfull, so instead of just stopping the other electrons, pushing them violently away? Hopefull

All charged particles obey the same laws of electromagnetism. The force only depends on the charges and the distance between them; no other properties of the particles have any effect on the electric force. That said, pions rarely last more than a microsecond, and down quarks can never be separated from other quarks because of color confinement, so neither can be "controlled in sufficient amounts". —Keenan Pepper 20:26, 22 October 2006 (UTC)

can anything other than particles produce charge enough to repel objects instead of just stopping them or are particles always required, can a photon or electron be charged up with more energy to repel stuff? hopefull

I don't understand what you mean by "repel objects instead of just stopping them". Electrons repel other electrons. —Keenan Pepper 04:48, 23 October 2006 (UTC)

All matter that we know of consists of particles. Photons have no electrical charge and do not repel. Each electron has an unalterable charge of −1. Charge is not a form of energy and is a conserved quantity in all interactions, so it cannot be "produced". Two objects will repel each other if they are both charged and their charges have the same sign. Opposites attract. See Static electricity.  --Lambiam^Talk 09:57, 23 October 2006 (UTC)

What do you mean by particles? Aren't pions and down quarks particles? Isn't the only thing known to exsist that isn't known to be a particle or collection of them gravity? Isn't even that strongly suspected to be a particle? — Daniel 03:50, 29 October 2006 (UTC)

Another EM wind question

How powerfull EM waves are required to project air at the speed and directional focus of this weapon, would it be possible to create an EM version of this weapon http://en.wikipedia.org/wiki/Vortex_ring_gun in the future that doesnt need shells, instead accelterates the air useing EM radiation. not now but perhaps in the future. Been trying to figure this out with other facts, but figured i should just ask directly already. Robin

I'm not an expert, but I think the intensity of the radiation needed to result in a notable acceleration of the air would be such that you get a deadly EM-ray gun. The point is that most of the radiation would just pass through. You'd also need rather large amounts of energy.  --Lambiam^Talk 18:47, 22 October 2006 (UTC)

Affordable Device for Measuring soil water content

Simple and affordable: Is there a simple affordable device for homeowners to use to determine if there is enough water content in the soil. This is for gardening, lawn care, general landscaping. This would work at my home.

more complex but afforable: I have a background in electrical engineering and would like to find/put together an affordable watering system (soil moisture measurement, automatic watering system, feedback loop,etc..). I found some info on Time Domain Reflectometers and have worked with those for another application but suspect that is expensive. Just need some ideas to get started. I tried the cheap (<$50.00) water timers (time of day - battery, amount of time- mechanical) but have not found one that works. This is for a family owned farm. My siblings want a small garden but no one has time to make the 60-90 minute drive to water daily.

Eostdiek

Simple resistive moisture detectors fed to comparators to decide whether to turn water off or on is all thats needed. You could control from a computer-- but whats the point?--Light current 14:31, 22 October 2006 (UTC)

Controlling it from a computer would have some advantages:

• You could turn the water on and off from a remote site, via the internet.

• You could base how much to water not only on current soil moisture levels, but also on the weather forecast. This could either be done with a fully automatic system that reads forecast info or by a human who reads a forecast and sets the amount to water (if any), as appropriate. StuRat 20:31, 22 October 2006 (UTC)

A device called rapid moisture metre is availlable for soil engineering use.The device uses carbide which is mixed with the sample of soil and acetelyne gas is produced.The pressure of the gas is proportional to the amount of water in the sample.The device is easily availlable at soil lab equipment shops.amrahs 17:08, 22 October 2006 (UTC)

If you read the initial question, youll see that what you propose is not suitable becuase the questioner wants remote automatic control that your scheme does not provide.--Light current 17:54, 22 October 2006 (UTC)

IR remote

What exactly would you need to build a simple IR remote control. Like a TV remote, only more simple, just an IR on/off switch. Obviously other than just an IR lamp/receiver set.--71.247.247.67 13:50, 22 October 2006 (UTC)

• Basically, what would I need to make a simple one of these? and a matching receiver of course--71.247.247.67 13:53, 22 October 2006 (UTC)

Try Discover Circuits.[3]. There probably one there. Yes there is! [4] 8-)--Light current 14:21, 22 October 2006 (UTC)

What's this aprox. called again?

$\varepsilon \left[\Psi \right]={\frac {\left\langle \Psi |{\hat {H}}|\Psi \right\rangle }{\left\langle \Psi |\Psi \right\rangle }}$

It had a specific name, but I just can't place it, anyone?--71.247.247.67 14:16, 22 October 2006 (UTC)

• Nevermind, it just came to me, and this after about 20 minutes of playing with <math> markup--71.247.247.67 14:19, 22 October 2006 (UTC)

Aqueous Compounds

I know that when a metal is added to water a base forms, and when a non-metal is added to water an acid forms, but can someone explain to me the steps in which a metal or non-metal combine with water to form an acid or base? thanks

It's been many years since I took chemestry, but I seem to recall water being both a weak acid and a weak base, depending on what is introduced to it. Ah, I was correct: Water (molecule)#Amphoteric nature of water. --Wirbelwindヴィルヴェルヴィント (talk) 20:08, 22 October 2006 (UTC)

First of all, what you said isn't true for all metals and all nonmetals. If you add the metal gold or the nonmetal argon to water, nothing happens. Second of all, even those elements that do react with water do it by different mechanisms. However, there are some general trends. If a metal is reactive enough to displace hydrogen from water, then it does so in a redox reaction and forms the hydroxide. For example, alkali metals react like this: 2M + 2H₂O → 2M⁺ + 2OH⁻ + H₂. Nonmetals are usually more complicated; I think all the halogens undergo disproportionation reactions. —Keenan Pepper 20:18, 22 October 2006 (UTC)

Solar position equations

Every web site I have visited that computes solar position provides a list of the various measurements such as hour angle, declination, azimuth, altitude, etc. The problem is that they all seem to differ even when the exact same time, date, latitude and longitude is entered. I thought that I could resolve this simply by finding the equations from which these values were computed but again there are a variety of equations given to compute each value and non of the results agree with the computations done online. I thought at first the problem might be in conversions from radians to degrees and vise versa but the results are still inacurate or wrong. All I am looking to do is to replace a table of sunsets and sunrizes with an equation or series of equations that compute sunrise and sunset. Is there a web site or article where the equations are given and that will provide consistent and accurate results or am I doomed to using tables instead? Adaptron 20:35, 22 October 2006 (UTC)

I think that the reason the websites differ is because some compute sunrise/sunset according to the middle of the Sun, and some according to its upper edge. It is possible to calculate the Sun's position by yourself (a few months ago, I wrote a program to do it); however, you'll need a lot of equations, and your results will be nowhere near as accurate as the websites'.

I suggest using NASA's HORIZONS system. When it comes to accuracy, you can't beat NASA. The HORIZONS system can provide all kinds of information, including sunrise and sunset times. --Bowlhover 22:15, 22 October 2006 (UTC)

Assuming the output data is accurate I can use it for verification. However what I need to to be able to generate sunset and sunrise from within a computer program versus looking up the times. Accuracy is always important but reasonable accuracy is acceptable. While some web sites have reasonably accurate times the other values that are listed do not agree with other web sites or with the equations I have. There must be a web site somewhere that lists reasonably accurate equations with example data that can be verified unless this is considered to be some sort of secret doings that only a trusted few can be told. Adaptron 22:50, 22 October 2006 (UTC)

Note that the exact time of apparent sunrise would also vary depening on local geography and weather. For example, the Sun will appear to rise far earlier on the top of a mountain than at the bottom of the Grand Canyon. Certain atmospheric conditions will also cause more diffraction of sunlight than others, causing the apparent sunrise to occur a bit earlier. Perhaps some of your calculations are "tweaked" to account for the local phenomena in a particular location ? StuRat 23:57, 22 October 2006 (UTC)

Actually the irony here is that while the web based sunrise and sunset results displayed on the websites are seem accurate and identical it is the other values such as time offset, equation of time, solar hour angle, azimuth and zenith that are not the same. In addition the equations provided by the web sites are not the same and the results for sunset and sunrise are inaccurate and not the same. How can the web site provide accurate times for sunrise and sunset but not accurate results for the other values of for sunrise and sunset from the equations they provide??? A list of equations to computer sunrise and sunset from latitude and longitude (and elevation if necessary) do not seem that far fetched. I would think they would be located all over the web. When you consider all of the other detailed and deep depth coverage of even esoteric topics on the web it just does not seem to make sense that there is no web site that provides an accurate set of equations with examples and other details. I get the feeling that it is a jealously guarded secret. Adaptron 01:59, 23 October 2006 (UTC)

There's no secret. Try sunrise equation. For a very detailed tutorial on how to write a program to calculate the Sun's position, try this. Also, from the same website, this webpage gives a tutorial on how to compute sunrise/sunset times. --Bowlhover 02:49, 23 October 2006 (UTC)

The Earth is not a sphere but more like an ellipsoid. Differences in the model used for approximating the shape, and differences between that model and the actual shape, can make a difference for angles and other relevant quantities. These differences should be quite small, and I don't know if they could possibly account for what you see.  --Lambiam^Talk 10:09, 23 October 2006 (UTC)

Okay what appears to be the problem is that many of these sites want you to purchase their software including the Naval Observatory. Although the prices are not outrageous ($13 - $29.95) it appears that they are using the tactic of only providing incomplete, crude or outright incorrect equations while at the same time providing accurate results on their web sites. Although the equations they are using to generate results may be accurate, detailed and complete the ones they have published on the web site are not. Adaptron 16:01, 23 October 2006 (UTC)

Equilibrium Constant, Kp

I am studying equilibrium constants in my college-level chem class and am having trouble understanding reasons behind the directions of the reaction for the equilibrium. When dealing with gases, if the volume is decreased, the pressure increases and the reaction favors the side of the equation with the smaller number of moles of gas and vice versa. It does make logical sense that if there is less volume the reaction will favor less moles, but I am wondering if there is something more concrete to explain this. I think my teacher said the reason is based on the kinetic molecular theory, but I've consulted my text and another text and I don't see how the kinetic molecular theory can explain this. Can anyone shed some light? Thanks.71.240.47.118 21:06, 22 October 2006 (UTC)MS

In general, these kind of equilbria are determined by entropy considerations, but there's an easy way to talk about this particular case: whichever side of the equation has fewer moles of gas must, on average, be the result of synthesis and not decomposition reactions. Synthesis reactions will happen more frequently when there are more particles per volume, because there are more collisions (more attempts at combination). However, the decomposition reactions are not encouraged by a greater number density (at least, not nearly to the same extent), so when the number density increases it takes more molecules that can decompose to balance the increased number of combination reactions, so the equilibrium shifts. --Tardis 20:07, 24 October 2006 (UTC)

i have great cofusion in Kp n Kc. it has been observed that sometimes Kc is greater than Kp in some of the reactions while in some cases it is lesser than that???????why is that so i want a logical answer

Nails

Why do we have white part close to the bed of our nails? They look like half moons, and I could swear that at some point in my life they seemed more pronounced.. so what are they?

Svetlana Miljkovic 22:11, 22 October 2006 (UTC)

It's called the lunula; our article says only a little about its function. -- Finlay McWalter | Talk 22:17, 22 October 2006 (UTC)

I believe that's where the nail is still growing. After that point, it's just being pushed along. StuRat 23:44, 22 October 2006 (UTC)

If that is so, if you cut your nails flat then leave them to grow without cutting, the ends should take up the shape of the 1/2 moons-- Yes?.--Light current 02:10, 23 October 2006 (UTC)

Sort of. The shape of your nails depends on not only how they grow, but how they are cut and torn, bumped etc. But they do tend to grow in that shape which is why nail clippers are curved, and if you peel your nail off (not the whole thing, just the tip) it will make a curved shape. 74.117.47.205 03:24, 23 October 2006 (UTC)

Ah well, thats funny. I always cut my toe nails in a striaght line. And they continue to grow in a straight line! 8-)--Light current 14:57, 23 October 2006 (UTC)

Just because they are growing across a curved area doesn't mean they are growing at different rates, which is what would be needed to change a straight cut to a curved edge. StuRat 19:30, 23 October 2006 (UTC)

Rainbow

I am trying to help my son with his homework and we are stumped, please help. When you stand with your back to the sun, you see the rainbow with a circular arc. Couls you move off to one sidr and then see the rainbow as a segment of an ellipse rather than a segment of a circle? Defend your answer.

Did you read our article Rainbow? You can't move to one side any more than you can jump over your shadow, even if you take a big leap. Promise you won't attack our answer.  --Lambiam^Talk 22:44, 22 October 2006 (UTC)

In other words, of course you can move to one side from your starting position -- but just as your shadow follows you, so does the rainbow. It keeps its circular shape, which exists because the raindrops that light up with each particular color are the ones that form a specific angle with the sun and your eye. (There is a second angle for each color that also works, but less well, hence the double rainbows when the rainbow is intense enough.) As you move, the position where this happens moves with you.

If you're talking about a natural rainbow in the sky, when you move sideways the movement of the rainbow is usually too small to see. You move sideways 20 feet, the rainbow moves sideways 20 feet, but you're looking at it against a plain sky background or against a background of distant objects and you can't see 20 feet of motion at that distance. So you have the illusion that the rainbow is fixed in place. But try it with a spray of water that you can get close to, like from a fountain, or a garden hose nozzle (held by someone else and set to a fine spray). A lawn sprinkler would also work if it's the kind that makes a continuous fine spray that stays in one place, and still another choice is the spray from a waterfall if you can get close enough to it. Get the sun angle right and you'll easily see a rainbow. Now move and watch the rainbow moving with you.

Even with a natural rainbow you can occasionally see it move with you, if you're watching it from a moving vehicle and you catch it against the right sort of background. For example, I've seen this when driving past a mountain lake where there was a rain shower over the lake and sunlight shining on the rain; the rainbow could be seen moving against the mountains on the far side.

--Anonymous, 05:23 UTC, October 23.

Factual basis in psychology for claims about the power of the imagination

Frequently, we hear talk of how something bad has happened to someone, like a relationship has broken down, or they have lost their job or something, and people say that deep down, the person "wanted it to happen." For example, if someone has low self-esteem, and they get a really great job, they might (allegedly) sabotage themselves, and somehow contrive (subconsciously) to get fired, in spite of making every outward sign of effort. The idea is that the underlying self-image is more powerful than the determination to succeed. Presumably it can also work positively for people with high self-esteem. These kinds of observations are commonplace, but what is the scientific basis for them? Do psychologists believe in this power of the imagination, and do they base this on science, or their general understanding and clinical experience? The Mad Echidna 21:41, 22 October 2006 (UTC)

Coincidentally, there was a study in my home town just recently. It's not exactly like the examples you gave, but it's close. False stereotypes can affect performance: B.C. study. Anchoress 22:33, 22 October 2006 (UTC)

People who believe they're going to fail, no matter what, are more likely to fail, no matter what. The explanation is simple: they have no incentive to improve their performance. People who believe they're going to succeed, no matter what, are more likely to fail, no matter what. The explanation is simple: they have no incentive to improve their performance. (But they are more likely to bluster their way out of the mess they create.) Applying this pop psychology insight as a post-hoc explanation to failing individuals has a problem of unfalsifiability.  --Lambiam^Talk 10:25, 23 October 2006 (UTC)

Is the human brain a chemical machine?

I would like to ask some further questions. Is the human brain a chemical machine? Is thinking the result of chemical processes? 202.168.50.40 21:50, 22 October 2006 (UTC)

That seems a bit of an oversimplification. At the very least it is a combination of electrochemistry and chemistry. Read our article Brain, and check out the role of neurons. Then see also the arguments from various sides in Type physicalism.  --Lambiam^Talk 22:40, 22 October 2006 (UTC)

Francis Crick wrote a book called The Astonishing Hypothesis in which he observed, "a person's mental activities are entirely due to the behavior of nerve cells, glial cells, and the atoms, ions, and molecules that make them up and influence them." --JWSchmidt 22:44, 22 October 2006 (UTC)

This is a question that will seem more and more pointless, the older and more educated you become. The answer of course is "yes and no". The entire human body can be described as a chemical machine, and we learn more details every year. That perspective has yielded enormous understanding of mechanisms of inheritance, function, disease, and even some aspects of behavior and personality. On the other hand, there are many other perspectives about the human mind that also contain truth and wisdom, including some truly valuable insights from religious and artistic perspectives. Another perspective entirely is the interpersonal, the way in which our minds are shaped by our relationships with other people. None of these perspectives can be described well from the "chemical machine" perspective. Intelligent adults recognize that different perspectives are useful for different purposes, and choose the best perspective for a specific purpose. The chemical machine perspective does not tell you what would make your life worth living. alteripse 23:08, 22 October 2006 (UTC)

Reductionist answers can answer some kinds of questions very well, and some kinds of questions very poorly. Regarding the mind as a chemical machine is useful for answering some questions ("What is the physiological cause of happiness?") but not for others ("What is the ultimate cause of happiness? How can I achieve it with the people I love?"). Answering questions in only physiochemical terms is rarely useful for anyone but the physiologist or the chemist. --Fastfission 00:53, 23 October 2006 (UTC)

Obviously yes. How else do you thimk it works?--Light current 02:15, 23 October 2006 (UTC)

Perhaps we should say electro-chemical.--Light current 16:32, 23 October 2006 (UTC)

lens

What type of corrective lenses are in the eyeglasses of a person who is nearsighted?

Convex. The things can't start a fire at all. :( Hyenaste ^(tell) 22:36, 22 October 2006 (UTC)

I think concave, actually. See Lens (optics). A convex lens can be used to focus light to a point, and thus start a fire. A concave lens spreads light out, thus (sans modification) can not be used to start a fire. This error was made in Lord of the flies when the myopic (nearsighted) character Piggy starts a fire with his glasses[5]. --TeaDrinker 23:04, 22 October 2006 (UTC)

Oh of course. I was thinking mirror instead of lens (a convex mirror focuses light, ya?). Hyenaste ^(tell) 00:05, 23 October 2006 (UTC)

No, a concave mirror focuses light. A convex lens also focuses light, but you don't use it in a pair of glasses to treat myopia. You use it to treat hyperopia. --Bowlhover 01:56, 23 October 2006 (UTC)

You should all go see an optician! (if you can) 8-(--Light current 02:03, 23 October 2006 (UTC)

Lab report!

Hello there! I'm a little stumped with my lab report I have to hand in tomorrow. I'm quite stuck on a part where it asks me the molarity of my acid solution. The lab was a titration lab with HCl and NaOH. Currently, I have the volume of my acid solution and base solution. It asks for the molarity. I understand Molarity = Moles / Volume (Liters). How would i be able to find the moles of my acid? I don't remember correctly but is it possible to find moles from liters? --Agester 22:55, 22 October 2006 (UTC)

According to the hydrochloric acid article, the density of HCI is 1.18 g/cm^3. Since you know how many litres of the acid you have, you can use this to find out the mass.

Once you have the mass, you can calculate the number of moles it's equivilent to. One mole of HCI is equal to 36.46 g. --Bowlhover 23:20, 22 October 2006 (UTC)

I'm not sure Bowlhover's answer is correct - the density given is for a 37% solution of HCl, which may not be what you have. I would have thought that, given that the experiment was a titration, the purpose of it was to determine the molarity of your HCl solution by finding out how much was required to neutralise a given volume of NaOH solution of known molarity. What you need to do is to find out the molarity of the NaOH, then check the volume of HCl you'd titrated at the end point, and then using those figures and the equation of the reaction, determine the molarity of your HCl solution. --YFB ¿ 23:31, 22 October 2006 (UTC)

I know if i find the molarity of the acid OR base i could find the molarity of the other. The main problem is that all i have is the volume of BOTH the base and acid.... wait! i think i have an idea! since it's a one to one mole ratio (for neutralization which is what i did in the experiment!) wouldn't my moles be 1? since the formula is written as HCl_(aq) + NaOH_(aq) ---> NaCl_(s) + H₂O_(L) (coefficients are one) therefore my Molarity would be 1 mol / (my volume in L) for my acid / base?? --Agester 23:38, 22 October 2006 (UTC)

You're right that it's a 1-1 mole ratio neutralisation, but if you don't know the molarity of either solution then I can't see how you can find the molarity of one from this experiment (Acid-base titration seems to agree with me). You'll need someone more knowledgeable to help you here... all I have is my 4-years-neglected recollections of A-level Chemistry, I'm afraid. --YFB ¿ 23:47, 22 October 2006 (UTC)

Yes. This lab is killing me because I know so easily Molarity_Acid X Volume_Acid = Molarity_Base X Volume_Base. I could find out the problem of this in 2 minutes if they gave me either moles, or molarity of either acid and / or base! --Agester 00:00, 23 October 2006 (UTC)

The required information may be "hidden". For example, your lab manual might say something like, "The solution you will use for the titration was made by dissolving x grams of solid y in z liters of water. --JWSchmidt 02:44, 23 October 2006 (UTC)

Hmm thanks for the input all! I got it. I found out the molarity of the acid (HCl) was given as .1000 Molars (constant for this experiment). It was confusing because the lab manual said the Normality of the base solution was 5 N. And we don't use normality in our lab we use molarity. In addition, i don't think we used a 5 N basic solution since we diluted our base so heavily. I doubted the manual which is why i came here for help. (if i did use that 5 N i would've been in big trouble.) Thanks for the input everyone! --Agester 01:51, 24 October 2006 (UTC)

October 23

The "Wholly Grail".....

Let`s talk about the Wholly Grail if we could, for a bit. More specifically, Virtual Particles. You know, those "pesky" electron-positron pairs that are alleged to exist at this level. My understanding of these 'alleged' particles is that they don`t exist long enough to be REAL...i.e. they exist for shorter than a Plank second, therefore, don`t REALLY exist at all. This could bring Hawking Radiation into question. I have, I think, a VERY interesting follow-up to this but I`d like to 'hear' everyones` ideas about these 'alleged' existances first, for fear of sounding a fool. Please, no jokes! TY Dave 205.188.116.74 00:27, 23 October 2006 (UTC)

• Is your spelling of "Wholly" meant as some sort of pun? If so, I don't get it--64.12.116.74 01:17, 23 October 2006 (UTC)

• Also, may I suggest, if you want to sign with a name, sign '''name'''~~~~~, that way the name stands out more than with name ~~~~--64.12.116.74 01:22, 23 October 2006 (UTC)

I didn`t want to include a spiritual or religious connotaion. You can call it "Holy", if you want, but I`m strictly aiming towards science. There was no pun intended, to answer your question. I have no clue what the person is talking about in regards to "signing", sorry. Please keep to the main subject. Dave 205.188.116.74 01:29, 23 October 2006 (UTC)

I too am utterly confused about the title. Since when is wholly an adjective? As for the question itself (which, funnily enough, has no question mark anywhere), who ever said virtual particles were real? I'm sure by Plank second you mean Planck time, but virtual particles can exist much longer than the Planck time (it depends on their rest energy: the more energy they have, the less time they can "get away with it", according to the uncertainty principle for energy and time). Anyway, how does any of this "bring Hawing Radiation into question"? —Keenan Pepper 04:42, 23 October 2006 (UTC)

First, will you folks please drop the "Wholly" already? It`s amazing how often you JUMP on someone over a single word, completely forgetting/ignoring the question/comment! Sheesh! Second, who said it was a question?..."Let`s talk..." Third, I DID say, ""MY" understanding of...". Perhaps I was wrong there...forgot about energy/time. Fourth, assuming I was correct, just for an instant, perhaps a Plank second even,(the tiniest piece of Plank Time, thought you`d get that!) if virtual particles didn`t "last" long enough to be 'seen' by Gravity, then that would CERTAINLY put Hawking Radiation into question! I guess I`ll save my VERY interesting follow-up for when I have some more-interested listeners/readers. Any thoughts about Vacuum Genesis? Thanks, Dave 152.163.100.74 05:49, 23 October 2006 (UTC)

The Reference Desk is not a soapbox, bulletin board or chat channel. It is meant for asking questions to which you could not find an answer.  --Lambiam^Talk 10:42, 23 October 2006 (UTC)

• That question is crackpot physics. Hawking radiation is due to virtual particles. There's nothing 'holy grail'ish about virtual particles - they're a well-understood part of mainstream physics, unlike the question which doesn't seem to have understood any of the terms it's using: Planck time is an unrelated concept to virtual particles. You can have a virtual particle for as long or short time as you want. --83.145.46.141 14:06, 23 October 2006 (UTC)

How gyrocompasses work

After reading the gyrocompass article, I spent a long time trying to figure out how it works. The article describes 2 types of gyrocompasses: the first kind is filled with fluid, while the second kind has weights that pin down its gyroscope.

I pretty much understand how the first kind works. However, according to the article: "This friction force caused by the fluid results in a torque acting on the axis, causing the axis to turn in a direction orthogonal to the torque (that is, to precess) toward true North (to the North star)". Is the torque applied in the direction opposite to the direction the axis is travelling in? If so, how will this torque cause the axis to move toward the north star?

I have no idea how pinning down a gyroscope's axis will cause it to point north. Shouldn't it point east, because that's where the stars rotate around the celestial north pole as much as they do around the celestial south pole? Can someone explain what I'm missing here? --Bowlhover 01:52, 23 October 2006 (UTC)

The gyroscope's axis points north, the gyroscope spins around its axis. It points north because it is aligning it self with the earths rotation, the earth also rotates around an axis which points north. This might give you a broader insight: equatorial mount. Vespine 06:40, 23 October 2006 (UTC)

I know that, but how does it align itself with Earth's rotation? --Bowlhover 15:37, 23 October 2006 (UTC)

Because that is the only orientation where the gyroscope's axis will not experience a change to its angle due to the rotation of the earth. Hold a pencil vertically and then spin around with your arm out, if your friend looks at the pencil, it will look like it is pointing in the same direction while you are spinning. If you hold the pencil on an angle from vertical, the place where the pencil is pointing will change as you turn. You could do this with an actual gyroscope instead of a pencil and feel the actual force involved.Vespine 01:05, 24 October 2006 (UTC)

I don't think I've made myself clear enough. So, here is what I do and don't understand:

The gyroscope is spinning around its axis. Right now, its axis is pointing toward a certain part of the sky. Earth is changing its velocity by rotating, but the gyroscope tries to resist this change in velocity (due to Newton's first law of motion). As the result, the axis will point to the same piece of sky relative to the stars. This "piece of sky" will rotate around Polaris in a counter-clockwise direction, just like the stars do.

Since the gyroscope's axis is rotating around Polaris in a circle, it will rarely point directly north. As a result, torque has to be applied to decrease the size of this circle (i.e. force the axis toward Polaris). My question is: how will submerging the axis in a fluid force it toward Polaris? --Bowlhover 04:29, 24 October 2006 (UTC)

Mercury and Fillings

Can mercury from a 30 to 40-ish year old filling come out and be hazardous to you health? Deltacom1515 02:09, 23 October 2006 (UTC) 02:05, 23 October 2006 (UTC)

Current research and the accepted beliefs of dental health organizations hold that dental amalgam fillings do not harm your health. - Dozenist talk 02:10, 23 October 2006 (UTC)

Its not done me any haarm yet >Harr, Haa HAAA haarrr!! HHAAAAA!!! HAAAAAr haarrrr!. Where is that hatter? See mercury--Light current 02:13, 23 October 2006 (UTC)

It's believed to not be harmful. Although i'd say most people who've encountered mercury in a chem lab would have doubts about that statement. We actually have an article on this, take a look Dental amalgam controversy#Health effects generally --`/aksha 02:30, 23 October 2006 (UTC)

No one is disputing the effects of raw mercury. What is at question is the safety of amalgam in fillings. 8-)--Light current 02:39, 23 October 2006 (UTC)

.....amalgam's contain mercury. --`/aksha 02:56, 23 October 2006 (UTC)

Correct.... amalgamated with other metals and therefore not RAW! Read my original post again.--Light current 03:14, 23 October 2006 (UTC)

Yaksha, I certainly do not see mercury in a chem lab ever, but I work with amalgams frequently. To repeat, amalgam fillings are not considered harmful. - Dozenist talk 03:19, 23 October 2006 (UTC)

Salt is not harmful, even though pure chlorine and sodium are extremely harmful. Just because the original subsituents are harmful, does not mean the compound/alloy is. Generally, the more reactive (and therefore, usually the more dangerous) a chemical, the safer the compounds they create. If they release a lot of energy in a reaction, it is not easy to reverse the process. --liquidGhoul 12:09, 23 October 2006 (UTC)

The question was about "Can mercury from a 30 to 40-ish year old filling come out". Amalgam isn't meant to be harmful. It's believed the mercury doesn't do anything funny. But if the mercury came out? That's the point. And my comment about the chem lab was meant to be a joke. (Although i can't really imagine why a general chem lab wouldn't have some mercury somewhere, it's not that usual. Even my high school chem labs had it, never worked out why though, it's not like they ever let students near it...) The link to the Dental amalgam controversy was meant to be my answer. The article explains it all. --`/aksha 14:02, 23 October 2006 (UTC)

Archiving

This section has been moved to Wikipedia talk:Reference desk#Archiving. --hydnjo talk 00:20, 24 October 2006 (UTC)

Different roles for insects in a hive/nest

Hi - this might be a silly question, but can someone tell me the entomological term for the different types of members of, say, an ant nest - the soldiers, the workers, the queen - they're not separate species, of course; are they separate subspecies? - phenotypes? - breeds? - what's the correct word here? Thanks Adambrowne666 02:42, 23 October 2006 (UTC)

I don't know what they are. But i do know they're not seperate subspecies or breeds. It's not to do with genotype/phenotype either. Insects, especially community insects like bees and ants, commonly have permanent gene loss during development. So your queen and your soldier ant could have almost the same genes, it's just that the soldier ant losses a part of its genome permanently during development. Where as the queen keeps all the genes, obviously...since the queen does the reproducing. I'd assume different 'classes' in a nest are due to different genes lost, since all ants within one nest/community have very similar genetically. --`/aksha 02:55, 23 October 2006 (UTC)

They're called castes. - Nunh-huh 04:02, 23 October 2006 (UTC)

Effectively, they're just different genders. In a honeybee colony for example, the queen is female, the workers are infertile females (they have under developed ovaries, and can't mate, being inhibited by the influence of an existing queen) and the drones are males. The same is true of the ant colony (in this case, queen, worker, soldier respectivally). Martinp23 23:03, 23 October 2006 (UTC)

In fact that's true for bees, but not for ants. There are female and male soldiers, workers etc., but they are all infertile. --84.166.249.224 14:47, 29 October 2006 (UTC)

In case you're interested, there is only one queen in a honeybee colony, and she lays eggs which hatch into workers and drones. The difference between the two eggs is that the worker one is fertilised with sperm from a drone, and the drone egg isn't. Therefore, interestingly, the males have no father in a honeybee colony. To produce a queen, an egg is laid fertilised, like that for a worker, and is fed on an enriched diet of Royal Jelly, allowing her ovaries to fully develop. The queen mates once in her life with around a dozen drones from different colonies (who die after impregnating here) and she stores the sperm for the rest of her life (up to 5 years) within her body. </beekeeping lesson> :) Martinp23 23:03, 23 October 2006 (UTC)

Castes! Of course! Thank you very much. Adambrowne666 23:07, 23 October 2006 (UTC)

how may calories are in... me?

To start.... this is NOT A MEDICAL QUESTION. I do not intend to be eaten or eat myself. I am purely curious about this matter.

I am very curious about how many calories there are in me. I am a 5'1" 140lbs woman with a 32% body fat percentage. (I know, I know, I need to lose weight). This means that my "lean body mass" is appx 96 pounds. It would be easy enough to add together the calories of 96 pounds of say, ham, and 44 pounds of pure fat, but there is the issue of bones, hair, brains, teeth, fingernails etc. I am assuming that my organs will not be eaten (although it would be interesting to find out how many calories are in a human kidney or liver). So is there any way to find out what is the weight of my muscle, or non-soft-tissue? All help is appreciated.

PS: Is it legal to eat myself, say, if I am wearing a mask? What about a red mask? ;) 74.117.47.205 03:20, 23 October 2006 (UTC)

We have a dog and four cats and they seem to be trying (to eat themselves) on a daily basis and without masks. I don't know about the calorie part as they seem to neither lose nor gain weight.  ;-) --hydnjo talk 04:13, 23 October 2006 (UTC) addendum: If you want to do the math, one pound of fat equals about 3500 - 4000 calories (actually it's kilogram calories or kcals) and one pound of muscle (meat) equals about 1600 - 1900 calories (using the same colloquial term). Water makes up a significant part of your body weight (about 70 pounds in your case) so you'll need to subtract that out. Also, so as to confound your calculations even further, your 32% body fat percentage may include some of the water weight as does the muscle (meat) weight. All in all, your body properly preserved and so on. should provide enough sustenance for one person for several weeks however I would suggest including some vegetables and fruits for a balanced diet.  ;-) --hydnjo talk 04:50, 23 October 2006 (UTC)

I'm not sure what you are trying to get at. If all you care about is the total amount of energy within your body then a calorimeter should be used. Ideally, we put you into the "large" calorimeter and burn you alive and measure the total amount of heat release. Short of that, we use a cadevar in a body similar to yours and burn it instead. 202.168.50.40 04:27, 23 October 2006 (UTC)

Do bones have calories? What about hair, cartilage, eyeballs etc? I am not talking about my body as a whole, but rather the parts of my body that a human would consume if he were to eat me. 74.117.47.205 04:34, 23 October 2006 (UTC)

Since you weight 140 lbs, your body mass has about $5.70735888\times 10^{18}$ joules of energy on it (E=mc²), which gives $1.36409151\times 10^{15}$ kcal. Good luck on losing that. :) ☢ Ҡi∊ff⌇↯ 04:31, 23 October 2006 (UTC)

Umm, don't forget to subtract out the water and bone (hair, nails etc). --hydnjo talk 04:55, 23 October 2006 (UTC)

That's if you made her into an atom bomb... --Wirbelwindヴィルヴェルヴィント (talk) 05:23, 23 October 2006 (UTC)

Wow! I sure would like to get the concession rights for that one. Step right up ladies and gentlemen ... --hydnjo talk 05:46, 23 October 2006 (UTC)

Atom bombs work by exploiting the mass defect between different atoms to create its energy. Atom bombs are far less potent than the energy amount quoted above. That amount of energy (e=mc²) could only be released if you annihilated every atom (e.g. with an anti-person).Richard B 23:13, 23 October 2006 (UTC)

Fat and muscle contain water, I dare say that the kcals figure quoted above includes that water, it isn't kcals of "dehydrated muscle or fat". So I don't think you subtract the water from the calculations.... As far as "edible" goes, most of the body would be and have some sort of nutricius value, as far as eyeballs, cartilage, kidneys, lungs, brains. About the only thing I think isn't digested is teeth and hair, you'd have trouble eating the bones, but you would digest them, if you were to grind them up for example.Vespine 00:42, 24 October 2006 (UTC)

Feral Horses of the World?

Hi, I've been trying to research feral horse populations, but haven't been able to find many, just the well-known ones. I.E. Sweden's Gotland Pony or North Carolina's Corolla "Wild" Horse/"Banker Horse". (The only true wild horse is the Przewalski's Horse.) Can anyone point me to a good site/book that lists feral horses of the world? If not, could I please put in a request for such an article? Thanks in advance:) —The preceding unsigned comment was added by StandardSmiley (talk • contribs) .

The horse section of feral suggests that there are hardly any real wild horses, so any horses in the wild are likely to be feral. Confusingly, the wild horse article uses the term 'equus ferus'. But I don't really know anything about the subject. I'm just doing your work for you, looking it up in Wikipedia. Note, btw, that feral horse simply redirects to 'horse'. As for requesting an article, you can do that at Wikipedia:Requested articles. I have never done that, so I don't know how successfull such a request might be. DirkvdM 08:21, 23 October 2006 (UTC)

The confusing thing is that a Latin word meaning "wild beast" has been given a rather more specialized meaning when applied to animals; specifically: domesticated animals having reverted to a "non-domestic lifestyle". Equus ferus is simply classical Latin for "wild horse". When your compatriot Pieter Boddaert introduced the scientific binomial name, the word in English just meant "wild", "savage".  --Lambiam^Talk 09:29, 23 October 2006 (UTC)

Chlorinated water and eye damage.

Would my eyes be damaged from exposure to chlorinated water for 20-30 minutes a day? I often swim with my eyes open, and haven't noticed any damage to my sight in the six months I've been swimming, but wanted to make sure. —The preceding unsigned comment was added by 202.10.86.63 (talk • contribs) .

I assume you've read the medical disclaimer, so I'll skip the lecture. Swimming pools are "chlorinated" with hypochlorite salts like sodium hypochlorite (a.k.a. chlorine bleach). A quick search on Google Scholar for cornea hypochlorite damage doesn't turn up anything worrying. It causes "irritation" (duh), but I don't see any mention of long-term damage. —Keenan Pepper 05:03, 23 October 2006 (UTC)

No your eyes will not be damaged. Mine were not and I swam in chlorinated water for dozens of hours each week every summer for a few decades. Eyes open. I loved swimming underwater. Don't do it much anymore, tho. WAS 4.250 16:11, 28 October 2006 (UTC)

Fissile material

After obtaining enough fissile material, what would one need to do to create a crude nuclear bomb (assuming one also had trained nuclear technicians to do so)? Like, what kind of steps would ahve to be taken? For the record, I'm not a terrorist, I'm just writing a thriller for NaNoWriMo. —The preceding unsigned comment was added by 58.7.219.86 (talk • contribs) . 01:17, 23 October 2006 (UTC)

It's not just obtaining the fissile material - it's seperating it from non-fissile material. Fissile uranium and plutonium make up less than 1% of all teh uranium and plutonium in all of nature. So, you have to run it through very long pipes (3 miles or more); the lighter (fissile) material comes out first, and that's what you put in your bomb. The problem is that in order to make it run through the pipes, you have to bond it with flurine to make it Uranium hexafluoride gas. However, Uranium hexafloride is *extremely* corrosive. In early WWII test, it ate through a 3 inch think glass pipe in 10 minutes; and a 3-inch steel pipe in two hours. The next trick: coat the inside of the pipe with Telfon and your corrosion problem is solved (This is why Teflon was a major war secret). After that, it's relatevely easy to build a uranium bomb. A plutonium bomb requires a lot mroe work though. Raul654 06:04, 23 October 2006 (UTC)

That's only if you are trying to enrich the material yourself. No terrorist has the facilities to enrich their own material; they'd either try to buy it or steal it. Both would be somewhat difficult; I'm inclined to think stealing it would be slightly easier though not much (buying it already requires somebody to have access to it and be willing to stake their own life on it, and you also have a high chance of either ripped off by the seller or by accidentally trying to buy it from a CIA agent). --Fastfission 00:36, 24 October 2006 (UTC)

Read the Nuclear weapon article. I'm afraid that's all the help we can provide right now (and it's substantial). I usually don't speak for other users but in this case I'll make an exception; none of us are terrorists. Perhaps you could add your manuscript to Wikibooks as a token of thanks for our research. --hydnjo talk 06:04, 23 October 2006 (UTC)

Yep, and nuclear weapon design. If you've got enough highly enriched uranium, the task is conceptually simple - just slam two bits of it together at a reasonably high speed - the easy way to do this is essentially whack one bit of uranium in a custom-built cannon and have the other bit at the end of the barrel. With a bit of experimentation, I reckon I and the local blokes down at the local welding shop would be able to do that. By contrast, if you're trying to use plutonium, it's a much, much harder task. You need to create a set of explosives that can "pinch" a sphere of plutonium into a super-compressed state, and then just as the compression reaches its maximum release a supply of neutrons that starts the reaction going - if you get the timing of the explosives or the neutrons wrong, you may get no bang at all, or a much smaller one. From the information to hand, it seems like North Korea's nuclear test was just such a "fizzle". --Robert Merkel 06:30, 23 October 2006 (UTC)

In The Fourth Protocol (film), you can see Pierce Brosnan assemble a nuclear bomb. Not too much detail, but it's a good film, so if you might ever want to watch it, now would be a good time. Btw, I like your disclaimer. I wonder what answers you would have gotten if you would have said you were a terrorist, since that would obviously have meant you weren't. Or would it? Let the double guessing begin. :) DirkvdM 08:05, 23 October 2006 (UTC)

Uranium bombs are easier to build - you just fire two sub-criticle masses at eachother, when they are close enough to make a criticle mass they explode, assuming enough neutrons are floating around in the environment. The WWII bomb had a 10% chance (if memory serves) of not working due to a lack of available neutrons.

Plutonium bombs need an initiator to supply a burst of neutrons at the right time to start the reaction (during implosion). The WWII bomb used a Berillium based initiator that is still classified (as of twenty years ago). Modern plutonium bombs use a minuture linear accelerator and target material for the initial neutron burst. Dallas67 10:25, 23 October 2006 (UTC)

The Little Boy gun-device also had neutron initiators. They wouldn't have left anything to such a high chance as 10%. --Fastfission 00:36, 24 October 2006 (UTC)

If you obtain enough fissile material you've gone 90% of the way to making a very crude nuclear weapon — fissile material will be the biggest and most difficult step for any non-state entity. You could create a pretty nasty explosion just by throwing a critical mass together any which way. It might not be on par with a kiloton-range weapon but it would be pretty impressive on a human scale. It really depends what you, the hypothetical user, are going for. If it is just a scary and deadly explosion you can get that without it being elegant from an engineering standpoint. The fancy implosions and all of that are for when you really want to get a VERY big explosion out of it; if you are content with something which is less than a kiloton in yield (which is still very large from a human point of view; the Oklahoma City bombing explosion was only .002 kt in yield) and radiologically messy you can cut a lot of complicated engineering corners. --Fastfission 00:36, 24 October 2006 (UTC)

On a related note: I've heard whispers of the theoretical possibility of a fustion bomb without a fission trigger, relying on super accurate implosion techniques. Does anyone have any information on this? Dallas67 02:11, 24 October 2006 (UTC)

That possiblity is discussed in Induced gamma emission and Sam Cohen and the book Imaginary Weapons. (Hafnium bomb) Current consensus says it doesn't work. --GangofOne 05:16, 24 October 2006 (UTC)

Might I point out that it violates the rules of NaNo to begin research before November starts? :(

Your uranium separation comments suggest that you are talking about the gaseous diffusion method of separating the 235 from 238. That takes a lot of space, money and time. Only nation states have those resources. Terrorists will either 'steal' the 235 or they will buy a flow forming machine and make thier own centrifuges. The centrifuge method of isotope separation is by far the cheapest and most space efficient way to do enrichment. The space aspect is important if you are trying to conceal the fact that you are doing it. The total number of centrifuges needed in a cascade system is dependent on the speed you can obtain with your centrifuges. Really good designers use magnetically levitated cans. Yes, there are tricks but then you would not need to show those on a movie. What you need to concentrate on showing is the fact that the centrifuge method of enrichment has changed the game totally and made terrorist nukes a very real PROBABILITY. They are cheap to build and easy to hide. That is scary! Forget calutrons and gaseous difussion. Today, that would me like using vacuume tubes to build a laptop.

Genetic tendancy towards AIDS amongst Black people?

It seems all statistics show that black people have a greater chance (up to 15 times!) more to get AIDS then a white person of European decent [6]. Is this a genetic tendancy or some other reason? Has there been any scientific studies? —Preceding unsigned comment added by 68.235.225.150 (talk • contribs)

The question is flawed. There is absolutely no genetic basis for AIDS. Raul654 05:59, 23 October 2006 (UTC)

I believe Africans have a high rate of AIDs, did you mean that? See AIDS#Economic_impact and the graph there, for example. But no, AIDS isn't a genetic thing; it has to do with behavior, which might be impacted by upbringing, family, where someone grew up, etc. --Wirbelwindヴィルヴェルヴィント (talk) 06:09, 23 October 2006 (UTC)

I am seeing different responces from different people. It seems most black professors who have studied the subject claim that AIDS is in fact a genetic disease, while white scientists claim that it is not. I haven't been able to find any scientific studies. 68.235.225.150 06:25, 23 October 2006 (UTC)

Indeed. It is probably due to behavior. --Proficient 06:27, 23 October 2006 (UTC)

Okay... just like any disease, there is a genetic component to HIV infection, at least with regards to susceptibility, meaning that there is likely some degree of variation; I recall reading a paper about a number of African women appear to be entirely immune to the disease, probably because they carry a mutation in a gene that affects the expression of the glycoproteins that HIV attaches to. I cannot say whether any particular population is more or less susceptible to HIV infection, (and I have no doubt that the answer is complicated by the fact that the strains of HIV that are prevalent in Africa are not the strains more common to Europe and the Americas) but I would think that someone, somewhere, managed to get grant money for such a study. If you find an answer, let me know. – ClockworkSoul 06:38, 23 October 2006 (UTC)

For a start, i believe the question you're really asking is whether Black people are more suspectible to HIV, the virus which results in the syndrom called "AIDS".

The answer is, yes, black people more commonly get HIV and are more 'suspectible' to AIDS. But it has nothing to do with genes.

Let's start with HIV.

• HIV originated in poor parts of asia/africa area, and didn't enter western society for quite some years. Not surprisingly since people from those poorer parts don't often immigrate to the western world. In other words, HIV has had far longer to spread in africa, where it's all black people.

• no one knew what HIV was at first. When it hit the western world - the western world keeps medical records, has medical databases, has hospitals and doctors and the facilities. When people noticed a how bunch of gay guys suffering from immuno-deficient disorders, they had the resources to investigate. They worked out what it was, what caused it, and how it spread. I'm afraid africa doesn't have those luxuries. Since AIDS is a slow disease (you don't get sick and die immediately from contracting it), AIDS probably existed and had time to spread for ages in africa before it hit the western world and got identified. In africa, HIV has had the chance to integrate into the population so much that children are often born carrying the virus these days (because their mothers do), which further increases the rate of HIV in those countries.

• HIV is spread primarily as a sexually transmitted disease. Condoms are rare in african countries, people do not have a culture of using them. Rape is also common. It's also common for men to have many wives. All these things means VERY easy transmission of HIV. In the western world, people are on average more monogamous (sticking to one sexual partner), condoms are readily avaiable and used.

• HIV is not acute - you get it and have no symptons for ages. In africa, many people probably don't realize it when they contract HIV. In the western world, people can access a doctor very easily. If they just get a little sick, they go see a doctor. Blood tests are easy to do, and experienced doctors will notice the symptons and diagonose quicky. People can then take measures to not spread it. In Africa, people get sick a lot more often, and don't have access to doctors so easily.

• Even in western society, black people are more likely to get HIV. This is because black people tend to be of the poorer, low social-economic class. Poorer means less access to medical facilities. Low social economic class means less education about health, disease, spread of disease, and safe sex in terms of sexually transmitted diseases. Poorer also means living in areas of higher crime, basically meaning more cases of rape and so on. You'll find that black people iin general tend to have more health problems, because they're poor and of low social-economic groups. HIV is not an exception, it's pretty much the norm.

now moving on to aids. HIV can stay in the body for a period of time without causing any harm. Up to about 10 years without medical help. At some point, no one knows what the trigger is, HIV activates and the body starts showing the symptons. These symptons are what's called the "Acquired Immune Deficiency Syndrome" (acquired refering to how AIDS is aquired from the virus HIV). --`/aksha 03:42, 24 October 2006 (UTC)

One tiny point: AIDS is called "acquired" because it's acquired from other people (it's contagious), rather than being genetic. --Tardis 19:13, 23 October 2006 (UTC)

Uhh...isn't it "acquired" as oppossed to cognetial? ...uh...however you spell that word. The one which means you're born with something. --`/aksha 03:42, 24 October 2006 (UTC)

Congenital means, literally, present at birth. Babies with AIDS still "acquired" it; they just did so rather early in life. The opposite here is really genetic, because then it's just that your immune system is inherently broken. Or perhaps it was simply not known that AIDS could be congenital when it was named, since "acquired" and "congenital" usually are opposites in medicine. --Tardis 23:25, 24 October 2006 (UTC)

• Once aids starts to show, people are more or less doomed to die soon. There are drugs to slow this process down, so HIV can lie dormant in the body for a long time and the person will not start to suffer from AIDS. These drugs are expensive - not the kind of thing that's regularly found in Africa. The drugs are also most effective if the person starts taking them as soon as they get HIV. Once again, black people who are of the poor social-economic groups tend not to do this. Some don't realize they have HIV. Others can't afford the drugs. Others simply can't be bothered. Hence the HIV infected black people develope AIDS much more quickly.

"I recall reading a paper about a number of African women appear to be entirely immune to the disease" they're not actually immune. There were reports of people in Africa who seemed to be infected with HIV and just carried it with them all their lives without realizing it. In other words, they lived long (long as in normal age for healthy people in their society) and normal lives despite having the virus. So for whatever unknown reason, despite being infected with HIV, the HIV never really activates in their body. So not exactly immune...more like being sick but just not dying. Which i guess is 'immunity' in one sense of the world. --`/aksha 13:54, 23 October 2006 (UTC)

The term for that is a carrier, with Typhoid Mary being perhaps the most infamous example. Another problem in Africa is the persistent myth that having sex with a virginal woman will cure the man of AIDS, while, in reality, it only spreads AIDS to the woman. Also, women in Africa are so dependent on men for survival that they must do whatever they are told, including having sex without a condom, even knowing that their man sleeps around. StuRat 19:20, 23 October 2006 (UTC)

Um, no there is a genetic component to susceptibility to AIDS. The HIV virus requires several proteins in order to attach to and infect a cell. One of these is the chemokine protein CCR-5. Patients who lack CCR-5 are relatively immune to infection by HIV!

why do i have a feeling that the only way someone can lack CCR-5 is if they don't have a functioning gene for it? --`/aksha 03:42, 24 October 2006 (UTC)

Does the CCR-5 gene do anything useful ? If not, we could wipe out AIDS by creating a virus that destroys that gene, then let the virus go free. StuRat 16:57, 24 October 2006 (UTC)

CCR5 discusses this in come detail. – ClockworkSoul 13:49, 25 October 2006 (UTC)

Come again ? Are those details about how HIV is spread ? :-) StuRat 22:34, 25 October 2006 (UTC)

Gamma rays

Why gamma ray is not a particle but a ray only? It is told that waves also behave as a particle, then why is it not true with gamma ray?

• It's not... Although the name is a bit confusing, gamma rays are simply the highest-energy example of electromagnetic radiation. Their particle is the photon. – ClockworkSoul 07:21, 23 October 2006 (UTC)

Make that the highest-energy range of EM. Just like visible light is an EM range, ranging from red to violet. Gamma rays, however, are not defined to have an upper limit. Something tells me that in reality there is a limit, but the article doesn't seem to say. DirkvdM 07:57, 23 October 2006 (UTC)

Cosmic Rays are supposed to have an even shorter wavelength.

But Cosmic rays are particles. ☢ Ҡi∊ff⌇↯ 15:14, 23 October 2006 (UTC)

At shorter and shorter wavelengths, dont these things appear more like high energy particles. All particles can be considered as waves and vice versa.--Light current 16:08, 23 October 2006 (UTC)

As Feynman said, they're particles, because you can hear the individual clicks they make in a Geiger counter. There's no such thing as half a gamma ray. —Keenan Pepper 19:36, 23 October 2006 (UTC)

But again, there's no such thing as a "particle" when one looks at the proper scale - gamma rays are just very high frequency/short wavelength light (with the attendent wave/particle duality involved). Virogtheconq 04:10, 24 October 2006 (UTC)

Application of Nature Cure for treatment psoriasis

Can you kindly explain whether Naturopathy can be successfully applied in the treatment of psoriasis of skin, where treatment by allopathy, siddhavaidya etc., have not yielded satisfactory results. If so. what are the sources (hospitals etc.,) available in Hyderabad? Regards Chandru —Preceding unsigned comment added by 59.144.66.3 (talk • contribs)

A very natural treatment is by doctor fish. I'm afraid this may not yet be available in Hyderabad.  --Lambiam^Talk 08:50, 23 October 2006 (UTC)

Some people have suggested that a change in diet can be helpful. Also, some preliminary evidence exists for positive results from topical application of some botanicals. --JWSchmidt 13:56, 23 October 2006 (UTC)

You are likely to get two very different kinds of answer to a question about naturopathy here, depending on whether the poster believes that naturopathy has any efficacy at all. I suspect that the majority of posters to this reference desk are in the latter group, but I may be wrong. I would not recommend wasting time on it myself. --ColinFine 15:09, 28 October 2006 (UTC)

alluvial sedimentary rock

what is an alluvial sedimentary rock? —Preceding unsigned comment added by Ali khoobani (talk • contribs)

Here "rock" is a mass noun. Alluvial sedimentary rock is an alluvial deposit consisting of rock.  --Lambiam^Talk 08:40, 23 October 2006 (UTC)

And I'll say it's a rock composed originally of alluvial deposits. :) --Zeizmic 12:43, 23 October 2006 (UTC)

heat

what generates the heat to melt the rock in the earth core? —Preceding unsigned comment added by Ali khoobani (talk • contribs)

According to the prevailing theory of planetary formation, planets are formed by dust and gas clustering together in increasingly larger clumps, finally collapsing together to form a planet-sized body. The heat generated by the kinetic energy lost in the impacts made the Earth melt. Since then it has only been cooling down. The generally accepted explanation is that the heat is simply left over from the Earth's initial formation; see Structure of the Earth.  --Lambiam^Talk 08:33, 23 October 2006 (UTC)

I sure wish I had cared more about global geophysics. Our article seems wrong about the source of heat for the earth. This [7] is more in line with what I understand. --Zeizmic 12:40, 23 October 2006 (UTC)

I agree, the primary source of heat in the earth is radioactive decay. If the earth had no internal heat source it would have cooled down a lot more already. Wikipedia does have some articles that mention this - see Geothermal power, Age of the Earth and Uranium. JMiall 12:57, 23 October 2006 (UTC)

This played an interesting role in the history of science. Before radioactivity was understood, people such as Kelvin claimed that their physical science theories for rates of cooling of the Earth and rate of chemical fuel depletion in the Sun showed there had not been enough time for biological evolution to take place on Earth. A good example of why scientific claims should always begin with, "If my assumptions are correct...." --JWSchmidt 13:39, 23 October 2006 (UTC)

What about all the pressure on the earth's core? That's what I always assumed made the nickle and iron in the core liquid. - AMP'd 14:09, 23 October 2006 (UTC)

No, high pressure forces most materials to become solids. This is why the very core of the Earth is thought to be solid, even though the mantle is molten, and the core is even hotter. StuRat 19:01, 23 October 2006 (UTC)

So I had it backwards? - AMP'd 02:20, 24 October 2006 (UTC)

In general, yes, although there are exceptions, as some materials, like water, are actually less dense as a solid. StuRat 16:53, 24 October 2006 (UTC)

Radioactive decay is what generates the heat. since nothing can burn in the conventional sense, this is the only possible answer (I think).--Light current 14:53, 23 October 2006 (UTC)

Also, tidal forces from the Moon and Sun generate some heat in the interior, but likely far less than radioactivity. StuRat 18:57, 23 October 2006 (UTC)

Current researches about earth core neutrinos try to tell the percentage of heat caused by radioactivity. It could be only 30-40%. -- DLL ^{.. T} 18:59, 23 October 2006 (UTC)

So what causes the other 60 -70 %?--Light current 00:21, 25 October 2006 (UTC)

I just saw a TV program on the Earth's magnetic field, which claimed the Earth's core is cooling at a rate of about 100 degrees (they didn't specify units) per billion years. How fast the initial heat (created by planet formation) would dissipate without radioactivity and gravitational tides was not exactly clear. When the mantle does solidify, in a few billion years, this will cause the magnetic field to cease, which, in turn, will cause the atmosphere and oceans to be driven off by the solar wind. StuRat 22:31, 25 October 2006 (UTC)

Unidentified Mushrooms

Unidentified mushrooms

What mushrooms are in this image? It's a very good image, and I would like to put it in the appropriate area, but I don't know what kind of mushroom it is. Chanterelle, maybe? NauticaShades 07:49, 23 October 2006 (UTC)

They certainly look like it. I wouldn't eat them, though, unless they are printed on edible paper. Did you think of asking the photographer and uploader André Karwath aka Aka?  --Lambiam^Talk 08:16, 23 October 2006 (UTC)

Oh man, so many witticisms in one reply, I think I'm going into repartory arrest! Anchoress 09:47, 23 October 2006 (UTC)

Google has 280,000 hits for "repertory arrest", and it is my sad duty to report that a lot of them seem to be talking about cessation of breathing, eg. respiratory arrest. JackofOz 09:56, 23 October 2006 (UTC)

Dood, you need to bone up on your ironical vocab. I meant repArtory as a mangling of 'repartee'. I assure you that clever word play is not sufficient to induce respiratory arrest, in me anyway. ;-) Anchoress 10:19, 23 October 2006 (UTC)

Oh, I detected the irony and the humour alright, although I admit I thought it was a mangling of "repErtory" rather than of "repartee". What's it called when you laugh at a joke for completely the wrong reason? Dorkness, maybe? But I don't think it matters as long as you're having jolly fun with your chums. Anyway, we've discovered a further reason to be cautious when a doctor uses big words.  :-) JackofOz 19:58, 23 October 2006 (UTC)

I love collecting edible mushrooms, but that looks like a pile of several types. --Zeizmic 12:25, 23 October 2006 (UTC)

Looks like chanterelles to me. I wouldn't worry too much about eating them myself. I've heard more than one mycologist say that chanterelles don't resemble any poisonous fungi. (And are therefore recommended to inexperienced mushroom-pickers). --83.145.46.141 13:53, 23 October 2006 (UTC)

Um, ah, well, it all depends where you live. If you happen to live somewhere that the Jack o'lantern mushroom grows (and glows), you can make yourself sick as hell if you confuse the two pretty orange mushrooms. We really oughta give the same disclaimer for mycology here that we do for medical and legal advice... --jpgordon^∇∆∇∆ 17:17, 23 October 2006 (UTC)

They do look a lot like chanterelles, and the fact that someone bothered to pick and dry a whole pile of them does suggest that they might be an edible species. Of course, I'm saying this safe in the knowledge that I won't be eating those particular mushrooms. Still, I'd find the identification sufficiently plausible for adding something suitably equivocal, like "probably chanterelles", to the image description, especially since correctly identifying dried mushrooms by sight is generally much less safety-critical than identifying fresh ones — dried fungi, if you didn't dry them yourself, usually tend to come pre-labelled. (And yes, jpgordon's point is important — just because a particular edible species looks like nothing else that grows near you doesn't mean there isn't a poisonous look-alike growing in some other part of the world.) —Ilmari Karonen (talk) 14:56, 27 October 2006 (UTC)

Chemistry/ Heat curves

How much energy (kj) is required to convert a 15.5 g ice cube at -5.0 to water vapor at 180 degrees Celsius?

Yeah, I had those questions in school too. You'll want to divide the problem into a few steps:

1. Heating the ice to the temperature where it can melt
2. Melting the ice
3. Heating the water to the temperature where it can evaporate
4. Vaporising the water
5. Heating the vapour to the final temperature

—Bromskloss 13:15, 23 October 2006 (UTC)

Sodium Dodecyl Sulfate

I did a Chemical Engineering lab last week to investigate the surface tensions of various concentrations of solutions of sodium dodecyl sulfate, also known as sodium lauryl sulfate. One of the aims was to discover the maximum surface concentration at the liquid/gas interface, and the minimal area of a molecule of said compound. This was done using the maximum slope of a plot of surface tension against log of concentration. Does anybody know the correct value for either of these, so I can analyse the accuracy of my results in my lab report? I only need one correct value because there is a simple relationship between the two. I already tried to google it but no luck, and I can't access the library at the moment.

Thanks! 7Munkys 13:07, 23 October 2006 (UTC)

Bad horror-movie bacteria!

How the hell do you kill these things??? Just reading the article is personally scaring the crap out of me! I mean, it can take heat, cold, vacuum, radiation, dehydration, even acid! Do you lock them up in jar and watch them starve them over three years? Do you try to poke it with a sharp stick? What? I really want to know! I need to be able to sleep at night! 83.250.208.83 14:57, 23 October 2006 (UTC)

Just put it in the oven and bake it for a few hours at 300 degrees Celsius. I'm sure it can't take that much heat. --Bowlhover 15:34, 23 October 2006 (UTC)

I'd prefer a plasma arc, if in fact, those things actually exist! --Zeizmic 15:46, 23 October 2006 (UTC)

One should consider whether it is, in fact, pathogenic before getting worried about them. Also, just because it is an extremophile doesn't mean it will flourish in normal environmental conditions, given that it is suddenly confronted with both competition and predators. —The preceding unsigned comment was added by 192.91.171.42 (talk • contribs) .

Exactly. They're probably harmless to humans. And Strain 121 can kick their asses anyway. =P —Keenan Pepper 19:45, 23 October 2006 (UTC)

Don't waste time; break out the phasers and photon torpedoes. B00P 20:38, 23 October 2006 (UTC)

Being extremophilic, I doubt they've had much experience of antibiotics, so a good dose of those could probably kill it. Laïka 21:37, 23 October 2006 (UTC)

If you're afraid of foreign creatures which can stand high temperatures, does that make you an xenophobic in regards to extremophilics? --Fastfission 00:23, 24 October 2006 (UTC)

Very cool - are there other bacteria like these two? Aaadddaaammm 03:38, 24 October 2006 (UTC)

Lots of weird extremophiles are being discovered [8]. Also, do you know the Archaea story? In 1977, biologist Carl Woese was working with bacterial cultures from deep underground when he discovered that they were not bacteria, with the result that today we say there are three types of life forms: prokaryotes (bacteria,) eukaryotes (protists, plants, animals,) and Carl Woese's archaea. Here's another: biologist Lynn Margulis proposes that all natural deposits of mineral ore are actually created by chemosynthetic deep-rock bacteria/archaea where different species metabolize each dissolved mineral from ground water while depositing the insoluable ore. Ever wonder why are there mines? It's because the Earth is like blue cheese! More like copper cheese, molybdenum cheese, etc. (Does this mean that we could pump seawater through bacterially-contaminated hot wet sand and later extract gold or platinum? Or how about Uranium?) --Wjbeaty 02:11, 25 October 2006 (UTC)

That's some pretty cool bacteria. --Proficient 02:30, 26 October 2006 (UTC)

Reishi and Birth Control Pills

Dear Wikipedia:

Good Day! My wife is taking some birth control pills but she's also taking some reishi mushroom for her health. Does reishi can hinder the effect of pills?

Thanks> Gerry

Please read the rules. "If requesting medical or legal advice, please consider asking a doctor or lawyer instead.--Russoc4 16:21, 23 October 2006 (UTC)

You could also ask your pharmacist. Make sure you can specify the specific pills used.  --Lambiam^Talk 16:25, 23 October 2006 (UTC)

The pill can be made ineffective if you experience vomiting or diarrhoea and this mushroom seems to have symptoms of gut clearing, so I would definitely check with a professional. Vespine 23:07, 23 October 2006 (UTC)

watershed management

how can watershed management be done? can you give an example of a place where this is being implemented?61.246.87.148 16:51, 23 October 2006 (UTC)abcd

I'm not sure what you mean. Do you mean management to prevent floods, to limit soil run-off, prevent water pollution, reserviors for irrigation and human consumption, sewage treatment, hydroelectric generation, etc. ? :-) StuRat 18:41, 23 October 2006 (UTC)

...or trying to get your kids to bed by 9pm?--Shantavira 08:48, 24 October 2006 (UTC)

Make sure they pee before turning in, or the bed could become a water shed. :-) StuRat 20:00, 24 October 2006 (UTC)

Alpha Helix

I am trying to do a quesstion for an university assignement and after looking through 3 text books, I am still puzzled. The question is as follows:

"The peptide chain below folds into an alpha helix. /an alpha helix is 0.54 nm long (5.4 Angstrom units) for every complete turn, and there are 3.6 amino acid residues per turn of the helix.

Lys pro val leu gly ala Ile ala asp leu val val gly leu glu ile leu ala val ala gly tyr ser"

I know this is kidna a homework question but I am officially stumped.

I am also to describe the nature of the protein (i.e. polar, non-polar, predominantly charged)

and finally,

If the hydrocarbon core of biological membranes is approximately 30 Angstroms, suggest a plausable function for the peptide.

Was there supposed to be a question already before you came to "I am also to"? If so, I couldn't find it! —Bromskloss 18:33, 23 October 2006 (UTC)

I apologise, it says I am to calculate the length of the helix. I got 3.45 nm.

• You might find it useful to read this article. It has more detail than do Wikipedia articles such as this one about how to make guesses about the functions of alpha helical domains.--JWSchmidt 22:14, 23 October 2006 (UTC)

You might want to visit the amino acid article and take a look at each individual amino acid in the peptide. Make a list of the charge and polar nature of each residue. For instance, the first residue is charged and polar. Look at the second residue very closely, as it will do something weird to the helix. Also, you basically answered one of your questions yourself: put the membrane thickness and helix length into the same units, and you might see a similarity.Tuckerekcut 23:07, 23 October 2006 (UTC)

Black Engineers

Hello. I was wondering, where could I find an article or a list of African American Mechanical Engineers? I searched this topic 3-4 times before, but couldn't find anything specific. Thank you for your time.

Thank you,
A Troubled User

See Category:African American inventors. StuRat 21:12, 23 October 2006 (UTC)

Crucell

Hie I am a wondering if you could possibly put up the Crucell's profile on wikipedia. Crucell is a leading Dutch Biotech company based in the city of Leiden. I am a press officer at Crucell so should you need some help compiling the profile, please feel to contact me on email removed

Thanks for the good work

Best regards

Bruce

We want money! --Zeizmic 21:20, 23 October 2006 (UTC)  :)

Of course, Wikipedia does not change editorial standards for pay. A good spot to list this would be Wikipedia:Requested articles. Standards for the inclusion of a corporation are noted at WP:CORP. Cheers, --TeaDrinker 23:12, 23 October 2006 (UTC)

a) That sounds like advertising, b) This isn't the request section, and c) I removed your email as per policy at the help desk. --Wirbelwindヴィルヴェルヴィント (talk) 23:14, 23 October 2006 (UTC)

C'mon, guys! That was unnecessarily rude and in bad faith. A simple Google search in Wikipedia shows that we already have 20 references to this company - among them the fact that they're part of the AMX index. So they clearly meet our WP:CORP criterium. — Sebastian (talk) 20:48, 25 October 2006 (UTC)

OK, I created the article: Crucell. — Sebastian (talk) 23:37, 25 October 2006 (UTC)

Algorithms

Just as articles need to be factual and accurate and subject to correction so do algorithms. So as not to break with the tradition of making encyclopedic articles as esoteric as possible is there an alternate place to post scientific and mathematical algorithms within the Wikipedia? Adaptron 21:38, 23 October 2006 (UTC)

Try Wikibooks. --JWSchmidt 22:19, 23 October 2006 (UTC)

Some can be posted here, like common sort algorithms. What does your do ? StuRat 23:13, 23 October 2006 (UTC)

I have many algorithms I am interested in posting but the current one involves the computation of sunset and sunrise from latitude and longitude. Except for one freely available from an online magazine I have yet to find any that are complete and error free. With a place set aside in the Wikipedia for publishing such algorithms I would hope such incompleteness or error would soon be eliminated. Adaptron 23:18, 23 October 2006 (UTC)

You've got a good idea for a new wiki there (WikiCode ?). I could post a few myself. What does everyone else think ? StuRat 23:39, 23 October 2006 (UTC)

If it doesn't belong in either WikiBooks or WikiSource, I would definitely be behind such an idea. It's a pity the Wikimedia Wiki-creation process is in a state of flux, or I'd suggest putting a proposal up right away. Confusing Manifestation 02:10, 24 October 2006 (UTC)

Here is a sunup/sundown computational algorithm in need of new wheels and a fresh coat of paint which it might acquire if left in a wiki instead of parked on the street.

Starting with the number of days since Nov. 17, 1858 or a modified Julian date of

JD = 2454032.24616, a computed event (sun up or down) set to UT = 0 or noon and an

estimated event set to UTO = 6 an iteneration is begun to compute the actual value

of UT.

(Note: addition of functions to convert degrees to radians may be necessary)

'initial values

Lat = latitude

lon = longitude

PI = 4 * Atn(1)

HORIZON = -50 / 60

while (abs(UT-UTO) > .0008

'compute the number of centuries since the epoch of Jan. 0, 2000.

T = (JD + UT / 24 - 2451545#) / 36525#

'compute the solar mean longitude

l = 280.46 + 36000.77 * T

'Compute the solar mean anomaly in degrees.

G = 357.528 + 35999.05 * T

'Compute the ecliptic longitude in degrees.

M = l + 1.915 * Sin(G) + 0.02 * Sin(2 * G)

'Compute the obliquity of the ecliptic in degrees.

E = 23.4393 - 0.013 * T

'Compute the equation of time.

ET = -1.915 * Sin(G) - 0.02 * Sin(2 * G) + 2.455 * Sin(2 * M) - 0.053 * Sin(4 * M)

'Compute the Greenwich Hour Angle in degrees.

GHA = 15 * UT - 180 + ET

'Compute the sun's declination in degrees.

DEC = arcsin(-Sin(E) * Sin(M))

'Compute the hour-angle at UT (the current estimate)

HA = arccos((Sin(HORIZON) - (Sin(Lat) * Sin(DEC)) / (Cos(Lat) * Cos(DEC))))

'Compute the time of sunrise, sunset, or twilight.

'RISESET is +1.0 for morning (rising) and -1.0 for evening (setting).

RISESET = 1#

UT = UT0 - (GHA + lon + (RISESET * HA)) / 15#

'The result is in hours.

'Continue until the UT and UT0 estimates are close together.

Wend

'print the computed event time.

print UT

Adaptron 08:42, 24 October 2006 (UTC)

Rate of lunar transit

What is the calculation or rate at which the moon 'crosses' the night sky? In other words, if you were watching a shadow on the ground cast purely by the moon's reflection, is there a calculable rate to ascertain how long it would take to travel an inch, or a foot?

The moon or a shadow cast by it is easier to imagine travelling in degrees, not feet or inches. Imagine a big tree and a little fence post, in one night the tree's shadow may travel dozens of feet while the fence post's only looks like it moves a couple of feet, the commonality is that both shadows travel the same number of degrees. The shadows turn, like the hands of a clock.

Obviously the 'turning' is caused by the earth spinning on its axis. The earth spins fully around once every 24 hours, meaning the moon looks like it is travelling 360 degrees every 24 hours, or 15 degrees an hour, (ignoring the much longer monthly period of the moon). If you do include the monthly revolution of the moon around the earth, it actually adds up, the moon travels forward by an extra 28th of a full revolution every day, or about 13 degrees, which is almost one hour, so every day the moon is almost an hour earlier.Vespine 22:47, 23 October 2006 (UTC)

Dear Vespine: Dynamite answer, in every fashion -- I'm very grateful for your help. Wolfgangus 01:17, 24 October 2006 (UTC)

I think the Moon lags behind the Sun; while it apparently travels from East to West like the Sun, it does so more slowly. See the picture at Lunar phase. This also explains why the path of the Moon's shadow during a solar eclipse travels West to East; see e.g. the animation at Solar eclipse of 2006 March 29. So "Moon rise" is a bit later each day. Using the value of 29.5 days for the synodic month, so that we have on the average 29.5−1 = 28.5 Moon rises in that period, the time from Moon rise to Moon rise is (29.5/28.5) × 24 hrs = 24.8 hrs = 24 hrs 50 mins. The overhead Moon traces out 360° in that period, which amounts to about 14°/hr = 0.25 rad/hr.  --Lambiam^Talk 06:49, 24 October 2006 (UTC)

Dear Lambiam: Thank you so much for the valued additional input. Now, if I may ask a question that perhaps begs the obvious: with all this in mind, does the Moon have a verified annual apsis and periapsis with the Earth? If so, how is it calculated?Wolfgangus 09:18, 24 October 2006 (UTC)

It has a perigee and apogee. I imagine this will be calculated assuming the Moon's orbit is a perturbed ellipse. Typical values for perigee is ~363000 km, and for apogee ~406000 km. Richard B 11:31, 24 October 2006 (UTC)

After edit conflict:

Stuff like this can even affect politics. After the Venezuelan coup attempt of 2002, there was controversy over when certain footage was shot. The Revolution Will Not Be Televised (documentary) had the shadows cast differently from another shot, so the argument was used that they were shot during different parts of the day. But how far apart those images were in time depends on the size of the building that cast the shadow. If cast by a tall building, the shadow would move very fast. DirkvdM 09:22, 24 October 2006 (UTC)

Sometimes I have my doubts about the relative 'greatness' of the internet, but this brief forum alone merits its tremendous caliber. Thanks so much to everyone for your help.Wolfgangus 22:47, 24 October 2006 (UTC)

Abnormal waves and tides

Is tidal [and waves] data from ocean buoys available for download online? Adaptron 22:02, 23 October 2006 (UTC)

I don't think marine buoys are an effective means of measuring tide (which is an interaction with the shore). Other bouy data (NOAA data) can be obtained from the National Buoy Data Center. For tide information, you might try tides online (another NOAA service). --TeaDrinker 23:07, 23 October 2006 (UTC)

Sorry I meant ocean height (to include wave action) which includes changes caused by tides whether at the shore line or offshore. What I am ultimately after are the Fourier coefficients for all locations of measurement, either offshore or at the shoreline. Adaptron 23:28, 23 October 2006 (UTC)

Found it at harmonic_cons_defs Adaptron 23:42, 23 October 2006 (UTC)

October 24

Ivan Pavlov's Insomnia cure

Hello to all, I wanted to know about Ivan Pavlov's Insomnia condition, so far by other researches I found he developed some recipies or prescrpitions for his own condition, this help him to develope a new category of insomnia, is there anyone able to provide me with info about this prescriptios or recipies for insomnia treatment????

Sergio Mexico City

I'm drooling in anticipation of the answer. :-) StuRat 03:25, 24 October 2006 (UTC)

Beer, wine, or something else?

Would an alcoholic beverage fermented from coffee be considered a beer or a wine? I would intuitively say "beer", but I can't give a good reason for it. Does anyone know if such a drink exists? Bhumiya (said/done) 01:25, 24 October 2006 (UTC)

Coffee does not have (or has negligible amounts) of carbohydrates in it, so there's nothing to ferment into alcohol. --Pyroclastic 01:44, 24 October 2006 (UTC)

You can, however, get coffee stout :) GeeJo ^(t)⁄_(c) • 01:46, 24 October 2006 (UTC)

That stuff is God-awful. StuRat 03:22, 24 October 2006 (UTC)

Heresy! Respect the Gods X [Mac Davis] (SUPERDESK|Help me improve) 07:38, 24 October 2006 (UTC)

It is not uncommon to add flavours to alcoholic beverages, so why not coffee? (Apart from the fact that it might taste horrible.) Whether it is called beer or wine depends on what the basic ingredient is - grain or fruit, although the distinction is a bit blurred (and grain is actually a fruit). Note that if you add fruit to beer it's still beer, like with kriek. DirkvdM 09:33, 24 October 2006 (UTC)

I believe it's called Kahlúa, but that's not fermented from the coffee, just flavo[u]red with it.

Atlant 17:00, 24 October 2006 (UTC)

And there are drinks like Irish coffee which have alcohol and taste like coffee. But no, I don't think you can ferment coffee. Maybe if it wasn't dried and roasted and sat after harvesting in a vat for awhile? Then that might not taste the same as coffee at all. --Wirbelwindヴィルヴェルヴィント (talk) 17:51, 24 October 2006 (UTC)

Wet coffee grounds definitely mold, but the fluid that runs off is sure nothing I would ever choose to drink. StuRat 19:45, 24 October 2006 (UTC)

I was thinking more along the lines of fermenting the brewed beverage itself after the addition of sugar and yeast. I think it would turn into something resembling a wine, but I don't know how the caffeine and acid would affect the fermentation. Perhaps this calls for an experiment. Bhumiya (said/done) 01:31, 25 October 2006 (UTC)

Beware, experimental fermented beverages can be poisonous. StuRat 03:43, 25 October 2006 (UTC)

Of course they are, that is what we ferment them for. DirkvdM 07:26, 25 October 2006 (UTC)

I doubt simple fermentation of sugar would be likely to produce anything poisonous. My brother and I once did the same thing with sweet tea. Distillation, on the other hand... Bhumiya (said/done) 00:51, 26 October 2006 (UTC)

The distinct coffee flavour is largely due to the roasting, so indeed, it would taste nothing like coffee. I tasted a raw coffee been once and it made me wonder how people came up with the idea of coffee in the first place. Maybe from a burned bush? DirkvdM 07:26, 25 October 2006 (UTC)

I once bought some caffeine gum, to keep me awake while driving. They apparently just filled it with powdered coffee grounds, and it tasted like it, too. Yuk ! StuRat 22:09, 25 October 2006 (UTC)

Bugs Bunny and shotguns

Having learned virtually everything I've ever needed to know from Warner Bros. cartoons, I was wondering about an effect ol' Bugs pulls off occasionally. If you were to jam your finger(s) into the barrel(s) of a firearm, would they cause the gun to be destroyed? Would the force be directed backwards or would you still get killed? Not that I'm planning on trying this at home or anything (I assume you'd lose your fingers and I need to count for a living), but you never know what places life will take you and I'd rather lose two fingers than, say, my head. There's some neat stuff at Physics of firearms about guns exploding by being fired underwater, but that's not quite the same thing. Matt Deres 02:45, 24 October 2006 (UTC)

I would think this might work on a cheap gun, like the proverbial Saturday night special, which has a weak, thin barrel incapable of handling the additional back pressure. The fingers and hand of the person plugging the gun would definitely be destroyed in any event, and the shards of the exploding gun barrel might hit him, as well. StuRat 03:09, 24 October 2006 (UTC)

MythBusters covered this in Season 3, see "Finger in a Barrel". --Canley 03:49, 24 October 2006 (UTC)

Basically, in that episode of Mythbusters, the dummy was killed (or would have been killed if it was a real person) when the gun fired. There was absolutely no damage whatsoever to the gun. The mythbusters even tried sealing off the barrel by soldering a large, iron cylinder into it. This time the barrel peeled back, but the cylinder was still fired out at a lethal speed. --Bowlhover 04:05, 24 October 2006 (UTC)

Right, but they probably used a decent gun. If you start with such a piece of junk that it's almost ready to explode on it's own, it doesn't take much to make it happen. StuRat 16:40, 24 October 2006 (UTC)

If you need your fingers to count, I would suggest abstaining from experiments with firearms. Or using Warner Bros. cartoons as a physics reference. And yes, your head is more important. - Samsara (talk • contribs) 09:21, 24 October 2006 (UTC)

One could just switch to octal, at least for the first two experiments.

Atlant 17:04, 24 October 2006 (UTC)

About the practical side of this. Just in case I'd ever come eye to eye with someone pointing a gun at me (however unlikely), if I could get my hand come close enough to the gun to put my finger in the barrel, that is not what I would do. I'd push the gun aside, possibly even take it from the gunowner. Faster, safer and more effective. Sorry to spoil this academic discussion with practical considerations. :) DirkvdM 09:42, 24 October 2006 (UTC)

I would stay away from the bunny, and go with the coyote! --Zeizmic 16:54, 24 October 2006 (UTC)

Relativity Paradox

I don't have much time to type this in but here is a quick and dirty relativity paradox.

Imagine a small black hole (in 2D space) with a circular event horizon with a radius of 1km. Therefore the circumference of the event horizon is 3.1416 * 2 * 1km = 6.28km

Now imagine a 10km (rest length) train travelling at near the speed of light entering the event horizon and going round and round in the event horizon. Because of the lorentz contraction, the 10km train is contracted to 5km so it would fit in the event horizon.

This is ridiculous that a 10km train can fit in a circular 6.28km event horizon "train track". What happens when the train slows down? The head of the train will crash into the tail of the train. Ridiculous!!! 202.168.50.40 02:53, 24 October 2006 (UTC)

I think I'm missing something, or the above is a little poorly explained. I don't quite see what the black hole is for in this example, why not just say a train track with a radius of 1km? And is the train crashing into its own tail really that ridiculous? Vespine 03:47, 24 October 2006 (UTC)

Why is it ridiculous for a train's head to collide with its tail? It's possible, isn't it?

Also, when the head of the train stops, the end of the train won't know about it until at least 33 microseconds later (10 km/299 792.458). (The real value is much longer, because the information actually travels at the speed of sound.) So for the first 33 micro-seconds, the end of the train would travel in exactly the same way as it used to. This will compress the train, squashing its unfortunate occupants to death... --Bowlhover 04:00, 24 October 2006 (UTC)

The train does not need to stop instantaneously. It can very very slowly slow down. Also, I put in the black hole to prevent the need for the train to exert a constant force, to cause a change in the velocity vector needed to get the train to go around an actual train track. 202.168.50.40 05:16, 24 October 2006 (UTC)

• Doesn't the black hole prevent the train from slowing down? - Mgm|^(talk) 08:01, 24 October 2006 (UTC)

Also, it'd be unable to support itself in orbit at the event horizon - it'd end up in the sigularity - and if you were looking from far outside the event horizon, you wouldn't observe the train crossing the event horizon - you'd probably just see it increasingly redshifted. Richard B 12:13, 24 October 2006 (UTC)

I'm not sure this problem is well-posed, or is a paradox, but if we're going to bring black holes into the matter remember that in GR geometry isn't what you're used to. For instance, I believe (although I might have it backwards) that the circumference as measured by a (stationary) measuring tape at the event horizon is in fact greater than $2\pi r$, where r is the radius of the black hole as measured by a distant observer. (This means that the distant observer describes the tape as being length-contracted even though it's not moving!) It only gets weirder if you allow the tape (or the train) to fall into the event horizon... --Tardis 15:45, 24 October 2006 (UTC)

You cant go round ad round in the event horizon. You are either inside it or outside it. If inside you wlii eventually rech the singularity. Isuppose you could orbit around safely if outside it--Light current 15:57, 24 October 2006 (UTC)

This must be some new meaning of "safely" with which I'm unfamiliar. (Apologies to D. Adams.) --Trovatore 19:42, 24 October 2006 (UTC)

What do you mean? THat you cant orbit around a BH safely?--Light current 22:30, 26 October 2006 (UTC)

Smoking Question

Disclaimer: I am writing a novel! Be assured I have no intention of forcing this upon a real human being or doing it to myself. The situation is that, due to a horrible trauma in one of my main character's pasts, he's decided he deserves to be punished. He's mentally unstable, and has OCD. He's afraid to die, because he'll have to face the person he harmed. So his punishment of choice is to smoke a certain number of cigarettes(thank the OCD...I don't know the number yet, but let's say 5) in a 30-minute(or so) period, then go without for 7.5 hours(somewhere around there), then repeat over and over. He's been doing this(or somethign similar) for 7-8 years. My question is, what would this feel like? I've gotten some descriptions of withdrawal from smoker friends, but none of them have any idea if this would feel the same way or not. Thanks for helping! Tigger89 03:18, 24 October 2006 (UTC)

If your main character doesn't get lung cancer, it'll likely feel pretty good to be addicted. Quitting smoking permanently is hard. But quitting for 7,5 hours--that should be pretty easy. --Bowlhover 03:44, 24 October 2006 (UTC)

I can share with you my experience, but you're really not specific enough so I'm not sure if I can answer it correctly. I smoked for about 6 years, when I used to drink or played pool, I sometimes smoked a lot, not quite chain smoking 5 in 30 minutes, but maybe half a pack in an hour or two. However, keep in mind that I also more or less quit cold turkey. And I didn't smoke hourly etc, so it fits your character fairly well. From my personal experience, no, the withdrawal isn't stronger in between the binges, so to speak, even after 5-6 years. However, I also smoke slower, 7-9 minutes for a cigarette, I think, so I definately couldn't smoke 5 in 30 minutes. So it shouldn't be any different than the withdrawal from a normal smoker, but that's just from my personal experiences.

However, I just have one question. Why is a person who's afraid to die smoking 3/4 of a pack a day? --Wirbelwindヴィルヴェルヴィント (talk) 03:47, 24 October 2006 (UTC)

The 3/4 pack a day thing...I really don't know, but I just know that's what he does. He started it when he was 15~, so maybe being a messed up teenager had something to do with it? Tigger89 04:27, 24 October 2006 (UTC)

• Talk about unstable. If he's afraid of dying, he shouldn't be smoking that much. - Mgm|^(talk) 07:59, 24 October 2006 (UTC)

If you use 5 cigarettes in 30 minutes, as Wirbelwind hinted at, for 30 minutes this character will be a furious smoker, almost cartoonishly so. The 8 or so hours between these tar-manias will be immaterial vis-a-vis withdrawal symptoms. From personal experience, I would say physical withdrawal symptoms don't begin for about 24 hours. Cravings in those 24 hours, yes; but true physical withdrawals beyond mental cravings, no. Additionally, chain-smoking in that way is one way to really punish your lungs, meaning when you tie together a string of cigarettes, you feel a unique, rather nasty congestion in your chest, as well as in your mouth. This character's hands will certainly stink (perhaps only an OCD hand-washer could rinse the stench off), and he should have brown, distinct stains where he holds the cigarette -- an often telltale sign in World War Two that a man was a spy; only they had access to enough cigarettes to put stains on the fingers.Wolfgangus 09:34, 24 October 2006 (UTC)

Defibrillator voltage, intensity and energy?

I have read so far the defibrillator article at Wikipedia but i am still unable to understand

• why doctors use the term Joule (as energy) in the sense to give to the patient an electrical discharge instead of using more appropiate electrical terms such as volts or intensity?
• What is the relationship of energy (joule) to volts and amperes given to the patient?.
• What are the maximum and minimum volts and amperes (intensity) reached by a defibrillator?
• Can a defibrillator be used to charge (electrically speaking) an car's uncharged battery?--HappyApple 03:38, 24 October 2006 (UTC)

Joule as you correctly identified is a measure of energy, neither electrical term such as volts or current. The relationship is V x I = P: Volts times Amps equals Watts. Watts are a measure of power, while energy is power applied over time. i.e. Joules = (Watts) x (seconds).

The maximum volts and amperes reached by a defibrillator seems not to be common knowledge, it is mentioned in the article that electrical burns are possible from insufficient contact with the electrodes so that suggest that the power is significant, since this power is achieved through capacitors it also suggest that the discharge is rather quick, which would also suggest that a defibrillator would not make a good car battery charger. A car battery requires a long slow low current charge, the defibrillator does the exact opposite..Vespine 04:44, 24 October 2006 (UTC)

Our Defibrillator page doesn't seem to have this info:( For some detail, check the inforesearchtizement for one manufacturer's equipment. DMacks 05:34, 24 October 2006 (UTC)

Ooo, if poor contact causes burns, what happens when there is good contact? Doesn't the heat just get produced in some other part of the body? —Bromskloss 07:42, 24 October 2006 (UTC)

Yes the heat gets produced in some other part of the body, but when the contact is good, the same amount heat is spread out over a much larger area and isn't enough to cause burns.Vespine 14:33, 24 October 2006 (UTC)

Also, there should less resistence if there is good contact. Therefore, the total heat produced should be reduced dramatically. StuRat 16:36, 24 October 2006 (UTC)

If the defibrillator delivers its full payload of energy under all conditions, then under all conditions n Joules (watt-seconds) of energy are deposited in the recipient's body. But with good contact, it isn't all dumped at the very surface of the skin, heating the skin to the burning point. Instead, it's much more-uniformly dissipated throughout the entire conduction path where the overall heating effect amounts to practically nothing. (4.185 joules of energy will heat one gram of water one degree C, so you can see that the overall heating effect of the impulse is pretty small, even at, say, 200 W-S.)

Atlant 17:11, 24 October 2006 (UTC)

If I have time tomorrow and no one else has answered definately, I'll look at it. But I found the 2005 American Heart Association Guidelines. From skimming, the human body is about 80 ohms, studies show that 30-40 A is probably optimal. The defibrillator resistance is around 50 ohms, and that's all I saw. I'll look at it more tomorrow. --Wirbelwindヴィルヴェルヴィント (talk) 08:22, 24 October 2006 (UTC)

Volts are the same as the unit Joules per coulomb. Amperes are the same as coulombs per second Richard B 11:18, 24 October 2006 (UTC)

enzymes

How many enzymes are needed for a human to stay alive. If memory serves me right, it is 500. I don't know for sure, though. --JDitto 04:06, 24 October 2006 (UTC)

I've never heard an estimate, but it would depend on how you classify enzymes. For example, do you count PKA as a single enzyme or a family of them? How about the PKCs? CaMKs? Hemoglobins? Acetylcholine receptors? You get the idea. --David Iberri (talk) 04:54, 24 October 2006 (UTC)

One list of enzymes is available at Wikipedia:MeSH_D08. --Arcadian 05:58, 24 October 2006 (UTC)

• When you take into account the amount of enzymes you need for even a single step in some cell transport processes, I find it hard to believe 500 is enough. I think it's far more, but I can't give a definitive number. - Mgm|^(talk) 07:58, 24 October 2006 (UTC)

So there's no definite list? Oh, man I don't think I have the time to count them all... --JDitto 22:46, 24 October 2006 (UTC)

From the enzyme article: Enzymes are known to catalyze about 4,000 biochemical reactions.. Of course, many enzymes participate in multiple reactions, but the 500 number still seems quite low. Has anybody thought to look at list of enzymes and/or Category:Enzymes? – ClockworkSoul 13:43, 25 October 2006 (UTC)

Why Does My Wife Kill Battery-Powered Wristwatches and Computer Hard Drives?

My wife kills battery-powered wristwatches in one to six weeks. We tried 8 different brands. She kills computers in three weeks to four months of daily use. She has done this for the last thirty years. We experimented with a wristwatch that had died and which began running again when she took it off. It quit working immediately upon being placed on her skin. The watch quit running a few seconds after being placed against her clothing. The watch began running again when it was placed more than eighteen inches from her body. My wife's cousin knew another lady who killed battery-powered wristwatches in a few weeks. In a medical test for metals retained in the body performed about 10 years ago, my wife tested perfectly metal-free. I had aluminum and copper and mercury and magnesium. Might this datum be related to her watch-killing phenomenon? Is watch-killing a common phenomenon? Is this related to a person's EM field? Can this watch-killing emanation be neutralized by some electronic device, similar to how sound waves can be neutralized with an electronic device? Does this watch-killing emanation have other aspects? What other methods might be used to neutralize this emanation? Would this emanation seem to be harmful to other people? Please comment. Marlin

That sounds really really odd. Though humans do generate an EM field (as do all living things), it's not very strong - certainly not strong enough to cause electrical interference (the body will couple with antennas, but that's an unrelated phenomenon). This seems more like a cause of really really bad luck, or something. I've actually never heard of such a phenomenon before, other than apocryphal bad-luck stories. Virogtheconq 06:00, 24 October 2006 (UTC)

At some point, you have to ask which is more painful to replace :).--Tbeatty 06:07, 24 October 2006 (UTC)

I used to wear my father's presumed dead pocket watch during carnaval. To my surprise it started running again, and accurately at that. After carnaval it died again, to be revived again next carnaval. Of course, that's a matter of moving the watch about, and actually the opposite of what your wife experiences, so this story is probably not relevant here. Sorry about that. :) DirkvdM 09:51, 24 October 2006 (UTC)

And now for something more relevant. Does the computer's hardware die (and which bit then?), or the OS? Does she install all sorts of stuff on it? If it's a hardware thing it might possibly be static discharge. Does she wear clothes that 'charge her up'? Do you get a discharge when you touch her? (No, I don't mean that.) DirkvdM 09:53, 24 October 2006 (UTC)

Sounds like my aunt, who is the only person I know who has this effect on anything electronic, mostly computers. Once we tested the phenomenon, she tried to dial-up with a modem and her daughter tried the same thing, and every time her daughter tried it worked. Weird. I would love to have an explanation for this. Her 'problem' is not as consistent or powerful as your wife's though; finally my aunt has found a laptop that seems to be behaving itself for the last few years. Could be due to a specific EM frequency that interferes with certain devices, as we are all beings of energy emitting a frequency ourselves. I wonder if it is linked to intelligence, as she is the cleverest person I know. BTW I've read somewhere that our EM should be in sync with the solar EM, or it leads to health problems - could anyone verify this? Sandman30s 12:10, 24 October 2006 (UTC)

Perhaps it's a static electricity thing. Maybe your wife wears insulating shoes/slippers and drags here feet when she walks, building up a static charge that's hard on sensitive electronic components. You might want to buy "ruggedized" computers and watches, which may have some degree of EM shielding, so aren't quite as sensitive to that type of thing. StuRat 16:27, 24 October 2006 (UTC)

Hey, don't steal my answers. :) DirkvdM 07:32, 25 October 2006 (UTC)

Try this experiment: give your computer a very long monitor cord, long keyboard cord, and long mouse cord. Then let your wife use the computer while ten or twenty feet away from the computer case itself. If her body is somehow affecting the computer hardware, this may stop the failure. --Wjbeaty 02:00, 25 October 2006 (UTC)

About watch-killing: these reports are fairly common, see [Unusual Phenomena Reports, "Electric People" http://amasci.com/weird/unusual/zap.htm] From the way most people describe the effect, "watch killing" is totally outside of conventional science. Human bodies don't have a significant electrical field that could have an effect on a watch battery. So, if it really does happen, the explanation would contain a scientific revolution (sort of like discovering a genuine version of "subspace fields" from Star Trek.) --Wjbeaty 02:00, 25 October 2006 (UTC)

Could be just odds: Someone in the world *has* to win the zillion dollar lottery, and someone in the world has to break everything they touch. --Zeizmic 16:52, 24 October 2006 (UTC)

Perhaps she's a Stepford Wife and it's a result of the EMI that she produces?

Atlant 17:18, 24 October 2006 (UTC)

There is this Wal-mart that I go to that always charges me and whenever I reach for anything, I get shocked. I don't know why it happens and why it doesn't happen to people I go with either. So it's probably some sort of body chemestry, the way you walk, the clothing you wear, something to that nature. Of course, I don't break electronics often, as I'm usually the one who gets asked to fix computers and it works when I use it and they're like, "what did you do?" and I'm like, "Nothing." Also, when my ex-suitemate and I walked around anywhere, lights would go out very very often. Anywhere from garages to malls to you name it. I'm not saying it's supernatural powers, but I think there's something that amplifies or react to what's already there, which might be something as simple as more iron in the blood or how conductive you are etc. Maybe if you're not very conductive, you build up a charge and that affects things. I have no idea how it happens scientifically, or it's just very whacky coincidence. --Wirbelwindヴィルヴェルヴィント (talk) 17:45, 24 October 2006 (UTC)

My grandfathr had to carry a pocket watch, because every wristwatch failed. I think it may have because he worked hard outdoors and had particularly corrosive or salty sweat. Computers have sometimes failed, at lease in decades past, because of static electricity from users (generally female) who wear nylons, or wool, and are insulated by plastic shoes. A sizeable static charge can build up. Data processing rooms had controlled humidity to reduce static buildup. I can't believe anyone has a sufficient electrical field around their body (other than static discharge) to magnetize a watch. In my experience, I had to get within a foot of a conductor carrying several hundred amps to affect a watch.Edison 22:04, 24 October 2006 (UTC)

application

can provide me the uses of molecular markers in relation to fruits and vegetables?

• It would help if you gave a little more information about what you're trying to do. Have you googled for molecular markers or read our article about them? - Mgm|^(talk) 07:55, 24 October 2006 (UTC)

Touch lamps

How do those touch lamps that you can touch and they light on work? Body capacitance claims it is the body's natural EM field, but that sounds hardly right. X [Mac Davis] (SUPERDESK|Help me improve) 07:54, 24 October 2006 (UTC)

how about this[9] Xcomradex 08:17, 24 October 2006 (UTC)

A friend of mine built one based on capacitance for his computron. —Bromskloss 08:50, 24 October 2006 (UTC)

This question came up here before. The body of the lamp is charged and discharged repeatedly. The time it takes to charge and discharge is easy to measure and stays pretty much the same. When you touch it, your body changes the time it takes for the lamp to charge/discharge, allowing the lamp to know it is being touched. --Kainaw ^(talk) 15:21, 24 October 2006 (UTC)

How much energy does it waste with this constant charging/discharging?

One can charge and discharge an ideal capacitor (a capacitor with no leakage or series resistance) endlessly while wasting no power. But practically speaking, the complete controller probably wastes less than a watt; the gizmos are small and can be built entirely into lamp sockets, so they certainly can't be dissipating much power or they'd get hot.

Atlant 17:24, 24 October 2006 (UTC)

science

give information about nutriton

Welcome to Wikipedia. You can easily look up this topic yourself. Please see nutrition. For future questions, try using the search box at the top left of the screen. It's much quicker, and you will probably find a clearer answer. If you still don't understand, add a further question below by clicking the "edit" button to the right of your question title. --Shantavira 08:57, 24 October 2006 (UTC)

Great answer, hi-five! X [Mac Davis] (SUPERDESK|Help me improve) 18:41, 24 October 2006 (UTC)

Can I steal it? --Zeizmic 22:03, 24 October 2006 (UTC)

• Sigh* okay. X [Mac Davis] (SUPERDESK|Help me improve) 22:17, 24 October 2006 (UTC)

Receive information about nutrition from Shantavira's response. :)! --Proficient 23:56, 29 October 2006 (UTC)

Sitting up while asleep

I have never sleepwalked, but ever since I was a child I have often found myself sitting upright in my sleep, sometimes several times in a night. Sometimes I simply open my eyes to find myself sitting up, and other times I seem to be vaguely aware of sitting up as though "half-asleep". I'm not sure if it prevents me from getting the rest I need, but it might be bad for my back since I don't have good posture when I'm asleep...I'm not really worried enough to consult an expert though. I just want to know if anyone has heard of this before. I guess I am also curious about the causes of weird sleep behaviour - why me, what causes me to do this? --Grace 11:38, 24 October 2006 (UTC)

This sounds as though it is a harmless precursor to sleepwalking. Check out the last external link on that page. It would also be worth mentioning to your doctor.--Shantavira 12:26, 24 October 2006 (UTC)

I do stuff like that, although not as often as you. I never got it checked out though, I never cared that much. I will say, though, that I am far more likely to exhibit those types of behaviours when I'm very busy/stressed. Anchoress 12:41, 24 October 2006 (UTC)

Premature rigor mortis ? :-) StuRat 16:02, 24 October 2006 (UTC)

See parasomnia for more information. X [Mac Davis] (SUPERDESK|Help me improve) 17:56, 24 October 2006 (UTC)

audio timescaling

Can you tell me if pitch synchronous granular synthesis is equivalent to pitch synchronous overlap and add (psola) method? THNX! --Ulisse0 14:59, 24 October 2006 (UTC)

"Please don't double post" is at the top of the page. Your question was answered on the computing desk. X [Mac Davis] (SUPERDESK|Help me improve) 22:16, 24 October 2006 (UTC)

I'm sorry.. You're right but I didn't know whether was the fittest desk .. --Ulisse0 17:25, 25 October 2006 (UTC)

Unexpected Item In The Bagging Area

When my mum and I went to pick up a few groceries recently at our local ASDA supercentre, we decided to use the automatic checkout system where you scan your own items. We had to get the assistant to scan her ID card and pin at least four times! What is wrong with these machines? If we were going to steal something, we wouldn't put it in the bagging area, and these machines are so flaky that even if we did, the ASDA lady would just swipe her card and we'd get away with it anyway. At one point the machine told us to remove the unexpected item and as soon as we did, it told us that we'd removed an item and to put it back! --Username132 (talk) 17:08, 24 October 2006 (UTC)

The computer "knows" how much each item should weigh (based on its SKU number). After an object is scanned, the computer expects the total weight in the bagging area to increase by that much. But very light objects can fool it, especially if the scale, err, "bagging area" is already burdened by heavy objects.

Atlant 17:28, 24 October 2006 (UTC)

Yes, there's just no way the same scale can handle a 50 lb bag of dog food and yet still know when a greeting card is placed on it, and still have a reasonable price tag. They just need to trust their customers better. Perhaps they could have a "preferred customer card" (for those who have never tried to rip the store off) and only allow them to use the automatic check-out. StuRat 19:06, 24 October 2006 (UTC)

These automatic checkout machines still need work, that's true. Maybe RFID will provide the solution, where you'll be able to just put all your purchases into a shopping cart, walk through a scanner, and all the items in your cart will be recognised by the system. — QuantumEleven 11:44, 25 October 2006 (UTC)

Despite the problems, I prefer self-checkout, for many reasons:

• I can verify each price and complain when I'm overcharged.

• I can pack things as I want them, so the freezer items go together, for example.

• I'm not going to accidentally scan an item twice and not notice it, as a cashier might.

• I'm not going to confuse my groceries with the previous customers or next customers, as cashiers have done, even when using the little plastic divider (although those are frequently missing, too).

• I'm not going to put a greeting card down in the leaked milk from the previous customer, as a cashier would.

• Since one cashier now watches over 4 lanes, instead of one, there's the potential for this practice to reduce lines. I say "potential", however, because they are just as likely to fire 7/8 of their cashiers and have the lines be twice as long.

StuRat 21:55, 25 October 2006 (UTC)

Chemistry

File:FG08 03.jpg

Write the usual group configuration notation for each d-block group. How do the group numbers of those groups relate to the number of outer s and d electrons?

Aha! I think someone is trying to get away with not doing their homework themselves! :-) If you ask about the principle, rather than request the solution of your particular problem, you are much more likely to get an answer. As can be seen somewhere among the vast amounts of text in the beginning of this page, people here won't do your homework, but can perhaps help you learn how to do it yourself. (Also, it's a good thing to sign your comments with "~~~~".) —Bromskloss 16:14, 24 October 2006 (UTC)

This isn't homework. dudewhoaskedthequestion 11:43, 24 October 2006 (UTC)

Sure as hell sounds exactly like it. See electron orbital and the table to the right. X [Mac Davis] (SUPERDESK|Help me improve) 17:55, 24 October 2006 (UTC)

you owned me

Low testosterone and high hemoglobin/iron test

I have been on testosterone for 6 months because it was very low (way lower than norm). My dr. suggested I take a topical cream version which worked great. My problem is my iron was to high and getting higher each time I took a test. I gave blood as often as they would allow. My hemoglobin stayed high and got steadily higher which put me in a higher risk of heart attack or stroke. So the dr. as of this moment, is taking me off testosterone cream and wants to send me to another dr. that deals with this kind of thing. Can anyone explain in easy lay terms what is going on? How can a 46 yr. old man have second to the lowest testosterone level a dr. has ever seen and a high iron/hemoglobin count in the blood? I am 30 lbs. overweight and 6'5" tall. I am not sedentary, but work in an office long hours and travel a lot.

Any information would be great, but please only reply to this question if you know by experience or knowledge.

thank you, richard

If your elevated hemoglobin was only after you'd been using the testosterone, it's pretty much expected: testosterone will often cause an increased hemoglobin. So it may simply be an issue of working out an appropriate dosage. This is something that your doctor should be able to clarify. Presumably you are being sent to an endocrinologist for evaluation of your low testosterone. - Nunh-huh 22:41, 24 October 2006 (UTC)

I assume your doctor will send you to an endocrinologist, who can answer your questions and will not tell you that you have the "second lowest testosterone" he has ever seen. Your height suggests gonadotropins and maybe karyotype should be checked unless your parents were extremely tall; there may be other issues to be addressed. Good luck. alteripse 22:52, 24 October 2006 (UTC)

first sex

on 17 april 2007 i m going to married and till today i did not seen any nude girl so i am very much worried how i do a safe sex and how i find that she had the hymen tell me detail about the sexual intercourse

Although I doubt this is a serious question, read the articles on safe sex, hymen, and sexual intercourse. Click on any links you are not familiar with. Be warned though, there's some scary stuff out there. :yikes!: If you want to see a nude girl than go to nude. Or type it in google. X [Mac Davis] (SUPERDESK|Help me improve) 17:52, 24 October 2006 (UTC)

Enough internet access to ask a question on Wikipedia, but never seen a naked woman? That's like half the content of the internets... -- Scientizzle 19:36, 24 October 2006 (UTC)

You don't even need to search on the internet. You can see naked women on wikipedia right here. 211.28.178.86 12:49, 25 October 2006 (UTC)

Whats ur age?

Maybe he means nude girls in reality, i.e. not merely an image of one. --WikiSlasher 11:31, 27 October 2006 (UTC)

Where Art Though Contact Lens

If I rub my eye, sometimes my contact lens dissapears off somewhere under my eyelid and after much trauma comes back out, often folded. Where does it go and what happens to it on its journey? --Username132 (talk) 17:00, 24 October 2006 (UTC)

Mine also like to go for a "morning swim", somwhere under the eyelids, when I first put them in. StuRat 18:56, 24 October 2006 (UTC)

Don't rub your eye! But seriously, some people have perfectly spherical eyes, which leaves nothing for the lens to catch on to. Most people have slightly conical eyes and the curvature of the lens is happiest there. --Zeizmic 21:01, 24 October 2006 (UTC)

You might consider trying rigid gas permeable lenses. They're a bitch to get used to but they're far better behaved in my experience. EdC 21:23, 24 October 2006 (UTC)

vacuolated glandular endometrial cells

i have apparently got vacuolated glandular endometrial cells in my pap smear results - does anyone understand the pathology of these? Are they inevitably cancerous, or precancerous, or just a bit odd? I have to wait at least a month for a colposcopy, hence the need to ask here.

Thanks,

Scared 81.153.246.135 17:58, 24 October 2006 (UTC)

The article on Pap smear does not give much information about false positive results. I found an article that talks about "vacuolated to dense variable cytoplasm" in endocervical glandular epithelium during pregnancy and in the postpartum period. "In 9/11 cases, subsequent cervical smears on multiple occasions were negative." In this study, the pap smear false-positive rate was 44.8%. Results from one pap smear are fairly meaningless; there needs to be follow-up testing. --JWSchmidt 03:45, 25 October 2006 (UTC)

Thanks JWSchmidt - I hadn't found that article on pubmed - interesting. Looks like these cells can appear during/after pregnancy and then disappear so are probably hormone-related. In my case they've appeared without pregnancy so if anyone has any others leads please let me know. Searching for vacuolated glandular cells has taught me more than I want to know about sheep, flounders, algae and regularly-cycling women but I'm still in the dark as regards non-regularly cycling women!

Scared

Defibrillators and stupid people...

Anyone got any tragi-comic stories about idiots misusing defibrillators for kicks and giggles and the results thereof? There was a story in the news a couple of years ago about a doctor who decided (as a show of bravado) to place the paddles against his own temples and administer a jolt. I think he died, or at least spent a very long time in a coma. --Kurt Shaped Box 21:47, 24 October 2006 (UTC)

You might find it interesting to read about the War of the currents where Thomas Edison (no relation) had his people electricute animals from dogs up through an elephant to show AC electricity, especially at high voltage, was more lethal than DC. One of his assistants placed the dog on the energized metal plates and got the jolt, but lived to tell about it. Defibs were researched and promoted by electric companies to save workers who got electricuted, before they became a hospital fixture. Many electrical workers have been jolted by various AC and DC sources and lived to tell about it. Many did not survive. It's hard to picture anyone thinking it would be fun to get or give a high voltage, high current shock. Edison 22:15, 24 October 2006 (UTC)

Never underestimate the power of human stupidity, especially when alcohol or the words "I was only having a laugh" are involved. Defibrillators bring people back to life, remember? You see it in TV medical dramas all the time. I wonder how many of the people that know this also know that defibrillators can kill if used improperly? This story isn't funny at all, as an innocent person ended up dead but it does show that these incidents do occur - [10]. --Kurt Shaped Box 22:35, 24 October 2006 (UTC)

Even worse are the words, "watch this..." alteripse 22:53, 24 October 2006 (UTC)

"Don't worry - it's not loaded..."? "God says..."? --Kurt Shaped Box 22:58, 24 October 2006 (UTC)

How dangerous is it actually to undergo defibrillation? We may suppose that the patient is healthy (and thus of course not really in need of it) so as not to confuse causes of death or so. You really can die, you say? —Bromskloss 22:28, 24 October 2006 (UTC)

Very recently, here in Austin, Texas, a portable defib was applied to a high school football player who'd collapsed, and indeed saved his life. However, the Doctor's misuse of the defib calls to mind actors such as Jon-Erik Hexim, who put prop pistols loaded with blanks to their temples for "kicks and giggles" -- yet were not so fortunate as to score a leisurely coma.Wolfgangus 23:00, 24 October 2006 (UTC)

How's about the guys who find pieces of unexploded ordnance from whatever war was their last war and start messing around with them, assuming that they're duds? There was a story on the Darwin Awards site (can't seem to find it now) about a Vietnamese guy who found an old landmine and started stomping on it to impress his buddies in the bar, with predictable results. --Kurt Shaped Box 23:33, 24 October 2006 (UTC)

Where to buy sulphur

Are there any websites the sell pure elemental sulphur in small quantities (100-1000g)?

• Sure! [11], for example, $7.40 for 500g. Just do a Google search for "chemical sales' -- there are lots of sources. --jpgordon^∇∆∇∆ 22:22, 24 October 2006 (UTC)

You can also buy it at many agricultural stores. I don't know what farmers use it for, but it is usually there. --liquidGhoul 23:34, 24 October 2006 (UTC)

Brimstones "Я" Us ? :-) StuRat 03:33, 25 October 2006 (UTC)

Brimstones ya us? DirkvdM 07:41, 25 October 2006 (UTC)

See Toys "R" Us. --Tardis 15:19, 25 October 2006 (UTC)

October 25

Function of small intestine

I met a fellow last night who has had all his small intestine removed. He says he feels ok and can eat anything he wants. What is therefore the function of the small intestine?--Light current 00:18, 25 October 2006 (UTC)

Did you ask him what his bowel movements are like? As I understand it, he'll have diarrhoea every time he uses the toilet because his gut is now not long enough to absorb the majority of the moisture/grease from the food he eats. --Kurt Shaped Box 00:21, 25 October 2006 (UTC)

He didnt mention bowel movements but implied all as normal and he felt really fit!--Light current 00:24, 25 October 2006 (UTC)

Could just be one of those wierd strokes of luck, then (either that, or your buddy is trying to make light of things). There was once someone who got shot in the side of the head, lost almost 50% of his brain and still made a full recovery. Anyone know if that guy has a WP article? I saw a documentary on TV not so long back about him - I think he was Indian. --Kurt Shaped Box 00:32, 25 October 2006 (UTC)

Maybe he only had part of his small intestine removed. I didnt like to probe him too deeply in public 8-)--Light current 00:36, 25 October 2006 (UTC)

I believe the small intestine primarily removes nutrients from the food and passes them on to the body, while the large intestine primarily removes water. So, if his entire small intestine was removed he would have trouble getting his nutrients. If only a portion was removed, then his ability to absorb nutrients would only be reduced by that portion. Eating more food (and making sure it was nutritious) could compensate, in such a case. StuRat 03:30, 25 October 2006 (UTC)

Yes thinking about it, he cant have all of it removed or he'd be dead. What you say makes sense. 8-)--Light current 04:35, 25 October 2006 (UTC)

I believe there are people who've had almost their entire digestive system removed (due to cancer, for instance). They can still survive by getting their nutrition via an IV drip. Not pleasant, but preferable to death, for most people. StuRat 05:45, 25 October 2006 (UTC)

The small intestine has three parts, with different purposes. The duodenum receives digestive enzymes and chemicals from the gallbladder and pancrease, which mainly break down macronutrients, especially lipids, into manageable chunks, this section also neutralizes stomach acid. The jejunum pretty much is just a tube in which chemical digestion occurs and nutrients are absorbed. The ileum fulfills the same rolls, and also selectively absorbs vitamin B-12 and bile salts, and makes sure that the colon does not get overrun by bacteria by small intestreleasing lymphocytes. Water is absorbed mostly in the large intestine, so removal of the small intestine would not necessarily cause chronic diarrhea, though it probably often does. However, even with all of that, most of the jejunum and ileum can be removed without too much of a change in diet, because absortion of most nutrients can happen just about anywhere in the system. Tuckerekcut 21:43, 25 October 2006 (UTC)

Thats good to know!

--Light current 21:50, 25 October 2006 (UTC)

On a semi-related topic, there are people who have had their stomachs removed (I know of a group of cousins with a genetic tendency to stomach cancer) who seem to survive, needing only to eat less and more often. —Daniel (‽) 22:11, 25 October 2006 (UTC)

Latent heat

What is the explanation of latent heat of fusion or evaporation. Where does this energy actually go?--Light current 00:23, 25 October 2006 (UTC)

It takes energy to break the inter-molecular bonds.

Atlant 00:37, 25 October 2006 (UTC)

So its potential energy given to the substance?--Light current 00:39, 25 October 2006 (UTC)

I would say it's thermal energy converted into a higher energy state for the molecules. This heat energy would be returned during condensation. StuRat 03:15, 25 October 2006 (UTC)

Yeah but its not ordinary heat energy because the temperature doesnt rise whilst the latent energy is going in. So how is this extra energy stored? Is it bonding energy as Atlant says?--Light current 03:21, 25 October 2006 (UTC)

Seems like StuRat confused you a bit. The energy it takes to break molecular bonds is thermal energy, that is, heat. But there is indeed no change in temperature. This is why you distingish between "heat" and "latent heat" - the latter does not change the temperature, but it's still a form of heat. This is why temperature alone isn't enough to quantify the internal energy of the substance. --BluePlatypus 11:55, 25 October 2006 (UTC)

evaporation? in particular: "... as the faster-moving molecules escape, the remaining molecules have lower average kinetic energy, and the temperature of the liquid thus decreases. This phenomenon is also called evaporative cooling. ". Xcomradex 10:43, 25 October 2006 (UTC)

Same process, slightly different circumstances. The temperature of the liquid changes in that case because some of the energy required to break the bonds and evaporate is being drawn from liquid. But the temperature of the liquid and evaporated gas combined remains the same. --BluePlatypus 11:55, 25 October 2006 (UTC)

That's not quite true — the temperature of the combined system really can go down (especially if the escaping molecules "just manage it", so they're not moving very quickly). Of course, assigning a temperature to evaporating water is itself dodgy, since that system is not in thermodynamic equilibrium. The point is that water under no water vapor has an excess of energy (from the unnaturally complete degree to which the molecules are associated) relative to systems in equilibrium that seem to have the same temperature. So when some of the water evaporates, we discover that its "real" temperature is lower, corresponding to the state without the excess energy. --Tardis 15:15, 25 October 2006 (UTC)

Global population of gorillas?

Approximately what is the global population of gorillas? The article doesn't say. 68.37.115.8 00:28, 25 October 2006 (UTC)

The 2004 estimate was about 5000. [12] --liquidGhoul 01:11, 25 October 2006 (UTC)

Note that of the most famous variety, the Mountain Gorilla, there are only 380 left. DirkvdM 07:48, 25 October 2006 (UTC)

I didn't realize there were so few gorillas. --00:02, 30 October 2006 (UTC)

Volume of semen during ejaculations

I've measured the volume of my ejaculations and they usually vary between 4cc and 6cc. Isn't the average volume of an ejaculation supposed to be 10ccs? Does this mean that I'm less fertile than other men? I'm getting a bit worried about this but I'd feel stupid going to the doctors about it. --84.69.92.172 00:59, 25 October 2006 (UTC)

Do you have a measuring cylinder?--Light current 01:03, 25 October 2006 (UTC)

Yes. I know that sounds weird but I started checking it out after a woman said that my ejacualtions were weak. --84.69.92.172 01:05, 25 October 2006 (UTC)

Short answer: Most likely, no. Less semen is not an indication that you are less fertile. Maybe someone else would like to give the long answer.--Russoc4 01:05, 25 October 2006 (UTC)

Someone said here a few weeks a go that the more protein you eat the greater the volume is! 8-)--Light current 01:08, 25 October 2006 (UTC)

Almost right. I said that, since excess protein is used to create sperm, your sperm production will go up if you eat more protein. However, since the majority of seminal fluid is not sperm, but rather water, a reduction in the amount of sperm won't necessarily have a noticeable effect on the total volume. However, low sperm production does lead to a lowered sex drive, which could result in fewer ejaculations. In this case, each individual ejaculation could actually be larger in volume. StuRat 03:11, 25 October 2006 (UTC)

Someone said something about eating loads of asparagus too. No idea if it works or not - I can't stand the stuff, in spite of its alleged benefits. --Kurt Shaped Box 01:10, 25 October 2006 (UTC)

Ah-ha! Snopes' article on the band 10CC says the average is only about 3 cc anyway. Confusing Manifestation 02:36, 25 October 2006 (UTC)

1. Each ejaculate contains 3-10 million sperm cells or so. I don't know the exact figures, to be honest, but I think it's around that range. I highly doubt 3 million sperm cells are going to make you infertile.

2. The only thing I have heard about asparagus is that it makes semen taste and smell horrible to people who can detect the enzyme (if you eat asparagus and can smell an awful smell in your urine afterwards, you can).

3. I don't think it's extra protein, else if someone has no extra protein, they won't produce any ejaculate, which I don't think is true.

Yes, during periods of starvation, both male and female reproductive systems shut down, as part of the starvation response. StuRat 17:11, 25 October 2006 (UTC)

4. And as for the strength, there are excercises to strengthen it. I read a long time ago about a hot and cold home remedy for weak ejaculations. Something about alternating hot and cold somewhere by your genitals. But I have never tried, and I don't know if it's a myth or not.

5. Also, frequent ejaculations can make it weaker, I believe.

--Wirbelwindヴィルヴェルヴィント (talk) 05:50, 25 October 2006 (UTC)

I'd just like to point out that there really isn't much "extra" protein in the body. The pool of free amino acids in the body is only about 100mg in total. This amount is very strictly regulated by the urea cycle. Excess protein is very quickly degraded into aminos and turned into urea. There are plenty of proteins in semen, both intra- and extracellular, but semen is in no way an "overflow conduit" for excess protein, thats what urine is for. Also, sperm makes up a very small percentage of the volume of semen, most of the liquid comes from the seminal vesicles and prostate and BU glands, so volume is not a good indicator for number of sperm. Stimulating a cremaster reflex at the moment of ejaculation with a cold compress to the scrotum can help push all of the fluid out at the same time (by putting pressure on the perineum, there is little to no mobile fluid in the vas deferens themselves), but will not increase the overall volume. Finally, 6mL is typical for an adult, at least that's the "goal" volume for at least one sperm bank in my area. Tuckerekcut 21:31, 25 October 2006 (UTC)

It sounds like you misinterpretted my comments. I did not say that any excess protein is automatically changed into sperm, but rather I said that a certain amount of excess protein (beyond what is needed for life-critical functions) is needed for sperm production. Thus, an extremely low protein diet will lead to a substantial reduction in sperm count. StuRat 21:41, 25 October 2006 (UTC)

Fermenting blood to create an alcoholic beverage?

I'm sure that most people here have heard the urban legend that Jaegermeister is made from fermented deer's blood. I'm curious - would it actually be possible to ferment animal blood to make booze? --Kurt Shaped Box 01:37, 25 October 2006 (UTC)

Is there fermentation without sugar (or starch to turn into sugar)? Unless you are insulin-dependent diabetic, I don't think you'll have enough sugar in your blood to get any good results. Maybe the legend is based on diabetic deer. --Kainaw ^(talk) 01:41, 25 October 2006 (UTC)

Of course you could add sugar to the blood and ferment that. DirkvdM 07:56, 25 October 2006 (UTC)

Nope, never heard that legend. Seems a bit weird given how many people drink herbal-flavored distilled liquor. (E.g. Hungarian Unicum or Scandinavian Aquavit) Well anyway, it's possible to ferment into alcohol anything that has sugar in it. But blood doesn't have much sugar in it (even if you're diabetic). Grape juice, a popular object of fermentation, has over 100 times the sugar (by weight) that blood has. You'd be better of milking the deer and fermenting that. The Mongolians actually do that out of horse milk, see Kumis. --BluePlatypus 11:41, 25 October 2006 (UTC)

Though blood may have a small % of sugar. With a diferential mearsuring from 4% - 7%. It is possible to compound those sugar parts into a small volume. Having boiled blood to stabelize the environment for fermentaion I realized that all the blood tissue turns solid so addition water is needed. The water that remained when the clotted tissue is strained away contained sugar. It should be possible to rinse many gallons through one gallon of water. Or reduce the original batch by boiling off excess water (having myself condensed and carmalized the sugar to an imesurable state excess of 25%+). This extraction process has not been fermented long scale yet. The results will need studding. 11/13/08

Fermentation notes: Fermentation is slow or nothing. With a sugar level of 14% in 1/2quart volume. I added a small amount of Dried Malt Extract (DME). This addition was to support the yeast's nutritional needs. Later observation has shown a slow decrease in sugar. It may have been benificial to run a malt enzime to break down any sugar complexes in the blood sugar if they are in a complex form. Odor is pleasent. No visual defects. Sugar reading 12.5% 1/13/09

No, it was deer shit ;-) Sorry, this urban legend sounds just too brainless--Baruch ben Alexander - ☠☢☣ 04:52, 31 January 2010 (UTC)

Endangered large cats

What large cats are endangered? --68.37.115.8 01:47, 25 October 2006 (UTC)

There's a complete list (not just cats) at List of endangered animal species. I think the answer is roughly "all of them". -- Rick Block (talk) 02:20, 25 October 2006 (UTC)

thanks

Of the species mentioned in our article Big cat, the following are found on this list of endangered animal species:

• Tiger (Panthera tigris)
• Snow Leopard (Uncia uncia)
• Iberian Lynx (Lynx pardinus)

 --Lambiam^Talk 15:35, 25 October 2006 (UTC)

There are many more, e.g. the whole genus Parantica. Since they carry the common name "Tiger", I'm wondering if the information in Big cat is accurate. — Sebastian (talk) 20:37, 25 October 2006 (UTC)

Cotton

How does Damp Cotton Absorb Sulfuryl Chloride gas used in radical chlorination (what chemical reactions occur)?

So you've got cotton, "dampness", and sulfuryl chloride. What are the chemical formulas/structures of those things? What are some characteristic reactions of them (nucleophile, electrophile, acid, base, oxidant, reductant, radical initiator, radical quencher)? Can you think of a way any pair could react? DMacks 04:31, 25 October 2006 (UTC)

Also note that adding water to cotton will greatly increase the reaction surface area over plain water and a gas. StuRat 05:40, 25 October 2006 (UTC)

Electrolytes

How can you tell what is a strong or weak Electrolyte when you are given a chemical formula / compound(s)? Is there certain elements that define this? certain rules? (maybe like solubility rules ) And are most (strong) bases weak electrolytes and most (strong) acids are strong electrolytes? etc. In addition, the Strong electrolyte"For strong electrolytes, a single reaction arrow shows that the reaction occurs completely in one direction, in contrast to the dissociation of weak electrolytes, which both ionize and re-bond in significant quantities" how would you know when it would be both ionizes and re-bonds (or doesn't) if you just had the compounds' names? (sorry if i'm a little incoherrent)--Agester 04:20, 25 October 2006 (UTC)

The electrolytic strength of a compound is the degree to which it dissociates into ions in solution, which is always an equillibrium. So the strength/weakness is relative. Whether a strong acid/base is also a strong electrolyte depends on how it works. E.g. nitric acid dissociates very much into nitrate and hydrogen ions and is therefore a strong electrolyte. But ammonia, a strong base, will form ammonium ions from the hydrogen ions in solution, which has no effect on the solution's ionic strength. So it can correspond to both the solubility and the pKa, but not necessarily. --BluePlatypus 11:26, 25 October 2006 (UTC)

I understand what you said. However, how would you be able to know which is stronger or weaker electrolyte? For example H₂SO₄ is a strong electrolyte but H₂SO₃ maybe a weak electrolyte. What defines their difference with respect to electrolyte properties? --Agester 23:56, 25 October 2006 (UTC)

The best way is to look at the bond holding the H atom to the rest of the acid. If the remainder - what will eventually form the [conjugate base] or [acid anion] - contains some highly electronegative elements, the chances are that the bond to the H atom will be severely polarised and weakened, leading to a larger Ka value. Look at the Ka values of chloroethanoic acid, dichloroethanoic acid and trichloroethanoic acid to see what I mean.--G N Frykman 07:38, 26 October 2006 (UTC)

hmm... i see. I appreciate your help and everything and i understand it. However, I haven't learnt about pKa in my class yet so it's still a little unclear for me (I did read the pKa article and it would help me greatly if we were taught this when we were discussing what is a strong and weak electrolyte). Once again thanks for helping! However, i guess the only way for me to know is memorize what is a strong and weak electrolyte! 8( --Agester 00:51, 27 October 2006 (UTC)

Sense of Color In Animals

Is it true that some animals sense only black and white images not color images? Thanks!

Yes. its true. 202.168.50.40 05:17, 25 October 2006 (UTC)

Although grayscale might be a more accurate description than black and white. StuRat 05:35, 25 October 2006 (UTC)

Still more accurate might be 'light intensity'. DirkvdM 07:59, 25 October 2006 (UTC)

Also consider, for example, lepidoptera - butterflies - who ID flowers in the ultraviolet spectrum; the patterns and colors in the UV wavelength are drastically different than how we see them.Wolfgangus 05:54, 25 October 2006 (UTC)

This is known as chromacy. Humans are trichromats, because we see 3 "primary colors" (three sections of the "visible" spectrum) and mix them together to create our rainbow. As wolfgangus reports, some butterflies are tetra- or pentachromats, with four or five primary colors to work with. I have heard that there is some kind of shrimp that sees the world in eight primary colors, thus "octochromacy". Monochromacy is a more technical name for what you called "black and white" vision (with the additional explanations above). According to our article monochromat, sea mammals are monochromats, but not many other animals are. Dogs, as with most other land mammals, are dichromats, which have vision comparable to a color blind person. They can see colors, but not as many as the average human. See dichromat for further explanation. Tuckerekcut 13:05, 25 October 2006 (UTC)

The shrimp that you are thinking of is the mantis shrimp, which has the most advanced color vision in the animal kingdom. – ClockworkSoul 13:33, 25 October 2006 (UTC)

Let's not forget tetrachromats. --Kjoonlee 16:32, 26 October 2006 (UTC)

Thanks to Tuckererkcut - a far more comprehensive explanation, which taught me a number of things as well.Wolfgangus 13:46, 25 October 2006 (UTC)

400Hz Frequency Apllied to Copper Conductors.

Hi,

Can anyone tell me how the use of 400Hz frequency affects the cable characteristics used on a 230V 63Amp supply. I believe that the increase in frequency increases the inductive reactance, decreases the capacitive reactance by up to a factor of 8. This then in turn affects the resistance of the cable by increasing it by a factor of 8. If this is the case how would one go about estimating the approximate cable sizes required for such an installation.

Thank you very much.

As part of your project, see Skin effect. Then grab a good electromagnetics textbook and a computer modelling and graphics program which can solve for the current distribution as a function of frequency and current. Have fun. Edison 17:25, 25 October 2006 (UTC)

I believe 400Hz is a common supply frequency for aircraft--Light current 15:22, 26 October 2006 (UTC)

Cable sizes are usually worked out on current. You dont need to worry about frequency IMO.--Light current 15:23, 26 October 2006 (UTC)

As the frequency increases, more of the current flows along the outer portion. Once again, read Skin effect.Edison 22:52, 29 October 2006 (UTC)

"scientific" name for grass. . .

. . .no, not canabus but the grass in your lawn. That name is needed for my son's class and he has not been able to find it anywhere. I know there are many kinds of grass but he was to find the scientific name for "grass" in general. Please help. . . I tried to find it here but had no idea how to start correctly. I did try a little but came up with nothing. Thank you so much, Mary McVey (I am using a friend's computer)

• Take a look at the lawn article. You will find what you need there. :) – ClockworkSoul 17:22, 25 October 2006 (UTC)

• As a hint, try clicking on the links in the first proper sentence in that article. Skittle 22:48, 25 October 2006 (UTC)

Amazing stuff, grass (even if we exclude the cannabis variety). Not only very useful to humans, for our lawns, food, construction, musical instruments and paper. But also, it's extremely simple and successful (the most successfull plant family even?). Yet it has only evolved very recently; for 99.8% of the evolution time span there was no grass. I wonder if there was something similar that grass replaced. Surely if something so simple can be so successfull, evolution would have come up with something similar sooner, right? DirkvdM 13:57, 26 October 2006 (UTC)

Grasses (or grass like plants) have been around for quite a long time, dinousaurs ate them. Also, evolution doesn't 'know' that something is going to be successful. And generally, whether or not something is a 'success' depends a lot on other factors. We have been amazingly successful 'til now (at least compared to many of the larger mammals) but it took evolution a long time to come up with us... Nil Einne 14:24, 26 October 2006 (UTC)

Yeah, but we're complex. Grass is simple, and I suppose that is part of its strength. DirkvdM 09:34, 27 October 2006 (UTC)

Insulation R-values

I have noticed a difference in R-values between similar products in Australia and Canada. 90 mm fibreglass insulation in Canada has a fairly standard rating of R-12 but a 90 mm product in Australia only goes up to R-2. Is there a different standard applied or is the manufacturing process that different? Any feedback would be appreciated. Thanks 209.89.148.249 19:17, 25 October 2006 (UTC)

Insulation materials are often characterised by their R value. In countries like Australia, which use metric measures, the units of R are m²K/W. An R=2 insulation material passes 0.5 watts per square metre with a 1 degree temperature difference. In countries using imperial measure, R is based on imperial units and a 50mm rockwool batt would have an R of around 40. --Zeizmic 22:57, 25 October 2006 (UTC)

Temperature - Kinetic Energy Relationship

I can't find a cogent equation anywhere to relate the energy difference between two states with temps T1 and T2. Any help? Thanks

First, find out the specific heat capacity of the material. Then multiply it by the difference between T1 and T2. Multiply this result by the mass of the material. --Bowlhover 20:45, 25 October 2006 (UTC)

Thanks! I'd forgotten that

Self-dissolving Miracle-Gro

What is the opposite of evaporation? Well OK, that's too easy - it is just condensation, but that _may_ not be what I'm looking for. I've got a packet of Miracle-Gro which is a popular plant fertilizer. You can buy it in a number of forms, but in this case it a box containing a plastic bag of blue crystals (looking rather like copper sulphate crystals, but I guess its more than that). You dissolve a spoonful in water before watering your houseplants every couple of weeks. Now, after opening the bag and leaving it around for about a year or so (my plants have a poor, impoverished and generally undernourished life - hey they are lucky to get watered), the blue crystals appear to absorb moisture from the atmosphere, to the point where they self-dissolve to form an aqueous solution in the folds of the plastic bag.

This strikes me as slightly unusual. Plenty of solids absorb water from the atmosphere, but AFIK few do so to such an extent that they become a liquid. So what is this process called? -- Solipsist 21:33, 25 October 2006 (UTC)

Sounds like they are deliquescent. DMacks 22:05, 25 October 2006 (UTC)

Yeah. They Stu stew in their own juice! 8-)--Light current 22:56, 25 October 2006 (UTC)

Taste and aging

Are you born with the all the taste buds you'll ever have or do they continually regenerate, like hair? What causes the loss of taste as you grow older? Clarityfiend 22:15, 25 October 2006 (UTC)

Possibly because elder people tend to take more medications, which may in turn produce that side effect. I'm not completly sure though. Hello32020 22:41, 25 October 2006 (UTC)

It is not the tastebuds that die along the way to getting old, it is the olfactory receptor neurons that do. One's sense of smell, along with mouthfeel, texture, and gustatory system sensations are the main contributers to taste. X [Mac Davis] (SUPERDESK|Help me improve) 07:16, 26 October 2006 (UTC)

And yes, they regenerate. Dismas|^(talk) 19:09, 26 October 2006 (UTC)

green leaves all over the ground

In my area (eastern Iowa, USA), fresh green leaves, rather than yellow, red, and brown, are littering the ground. There are still plenty of green leaves on the trees as well as some colored ones. I've never seen this happen before. We've had fairly normal winds. The fall season has been abnormal, with very warm alternating with downright cold. What gives?

Also, what causes the leaves to separate from the tree in the first place? I read somewhere it's not because the leaves dry up, but rather that the leaves dry up because of some process in the tree that more or less casts them off. Is there anything to that? --Halcatalyst 22:23, 25 October 2006 (UTC)

Try the Color change in leaves article. It says, among other things, "In late summer, the veins that carry fluids into and out of the leaf are gradually closed off as a layer of special cork cells forms at the base of each leaf. As this cork layer develops, water and mineral intake into the leaf is reduced, slowly at first, and then more rapidly. It is during this time that the chlorophyll begins to decrease." I'm sure we should have something else on the process somewhere. Skittle 22:45, 25 October 2006 (UTC)

The process is called senescence, but our article isn't that great with it. You are right, the plant does not just dry up. A lot of energy goes into creating the cells of a leaf, so they take as much of that back as possible. The reason the leaves change colour is that the chlorophyll is one of the things the plant takes back for energy. This removes the green colour. Since the most abundant colour is gone, the next most abundant becomes visible. The plant obviously doesn't want to lose its leaves beofre it takes out all the nutrients, so the process of abscission is next, and only occurs once the plant is finished with the leaf. Abscission also occurs with fruit, but in the opposite direction. The plant pumps in the nutrients, and once that is done, it will remove the fruit. --liquidGhoul 01:23, 26 October 2006 (UTC)

That, however, does not yet answer the question. Why do the trees not take the chlorophyl out of the leaves? Are there two disitinct processes for that and the abscission? Might senescence be controlled by temperature and abscission by time? That would explain it. DirkvdM 14:12, 26 October 2006 (UTC)

I couldn't tell you why this has suddenly occured for those trees. My bet would be that there was some kind of stress which caused the trees to shed their leaves. I doubt it is global warming, but it could easily be some sort of pollution. The triggering of abscission comes from the end of senescence. A healthy, green, leaf is constantly creating a hormone called auxin. As the leaf goes through senescence, the auxin levels decrease, which begins a series of steps which eventually leads to abscission. I think the beginning of senescence comes from day length, but it is probably very complicated (as all things living are), so there will be other factors. --liquidGhoul 15:03, 26 October 2006 (UTC)

I probably should know be able to explain the basics but but I've kind of forgotten most of it. However this article appears to cover the basics [13] and the links are helpful. However it doesn't really answer your main question. But as you may have gotten from you reading, senescence and abscission (as with most plant processes) are rather complex processes involving multiple hormones and multiple signalling pathways and it's not actually something we have a complete understanding of yet. Nil Einne 14:42, 26 October 2006 (UTC)

File:Dscn6245 wikipedia.jpg

Trees in Amsterdam on 24 October 2006

Btw, here in Amsterdam, most trees are still largely green, which is very abnormal for this time of year. However, the leaves that have fallen aren't green, so we seem to have more intelligent trees. :) Don't know what kind of trees they are, though, which will of course be the most important thing here. DirkvdM 14:12, 26 October 2006 (UTC)

reverse casimer effect??

I read somewhere that someone claimed that the casimer effect couldbe changed to be repulsive rather than attractive how can that be if the plates push together because of the zero point energy pushing on the outside of the plates, you cannot add to the zero point energy so how can this work. This is based on the NASA webbsite that describes the casimer effect much like air pressure, less between the plates so more pushing on the outside so they push together, how can you reverse this? FRed

Funny, I thought it was called the Casimir effect!--Light current 22:53, 25 October 2006 (UTC)

The plates would have to be close to massless, and extremely far apart for the effect to be "reversed," and is fairly implausible. X [Mac Davis] (SUPERDESK|Help me improve) 07:13, 26 October 2006 (UTC)

The idea of a reverse Casimir effect was discussed in the context of speculations whether very advanced technology worm holes might allow for time travel. Apart from giving fodder to SF authors this is of interest in research on general relativity: Due to the grandfather paradox causality would break down if it turned out that the laws of physics allow for time travel and if only under most exotic circumstances. In reasoning for the chronology protection conjecture it was said that a worm hole cannot be stable enough to send something into the past, and the counter-argument was given by Kip Thorne et al. that negative Casimir pressure might be used to keep it open. As I forgot the details I googled for Thorne and Casimir. You might find these links interesting: This science column from Analog Science Fiction and Fact that explains Thorne et al.'s work for the laymen and these notes on the homepage of Thorne's collaborator Matt Visser. Simon A. 13:03, 29 October 2006 (UTC)

October 26

When They Test You For Genital Herpes, Do They Take A Blood Test?

Like, how do they do it? Danke.100110100 01:04, 26 October 2006 (UTC)

IIRC, generally it's a blood test. Samples of an open sore can be tested, but that (obviously) requires that one already have a suspicious open sore on your genitals. DMacks 05:08, 26 October 2006 (UTC)

I'm not sure but I think this user might have a rather poor understanding of the human circulation system and may think you need to take blood from the genital region. You don't, the blood will usually come from the arm as always Nil Einne 13:58, 26 October 2006 (UTC)

A blood test for HSV2 (genital herpes) does exist, and tests for the antibody (the thing you producde to fight it). Alternative methods include swabs of the genitals, and pcr amplification of the material found. The latter I have seen only in academic studies. --TeaDrinker 19:27, 26 October 2006 (UTC)

There are several ways to test for genital herpes infection. One method of testing is a viral culture from a smear or swab of a vesicle (blister). That test is not perfect; it will be positive in about 70% of active lesions. Direct fluorescent antibody testing of a smear of vesicle fluid is about 90% sensitive. Polymerase Chain Reaction (PCR) testing is very sensitive but is also very expensive and therefore not typicaly used for routine clinical diagnosis. Blood tests are useful in two situations in regards to genital herpes infection. First, in a person who is experiencing what appears to be their first herpes outbreak, blood tests obtained when the rash breaks out and about 2 weeks later will demonstrate an increase in antibodies to Herpes Simplex Virus (HSV), thus strongly supporting the assumption that the herpes virus casued the original outbreak. The second situation in which blood tests can be useful is to rule herpes out as the cause of a chronic recurring genital rash. If a serum antibody test is negative for herpes, that strongly suggests that herpes is not the cause.

Microscope Lenses

My teacher gave a very bizarre and un-scientific sounding explanation for how lenses work within optical microscopes. They were talking about reflective lenses, giving a diagram of a curved lens reflecting directly away from it, resulting in a larger image on the same plane as the original. After what I already know, and reading Microscope and Lenses, I can see that they use refractive lenses on common optical microscopes. My question is this: Is it possible to magnify things reflectively, and is it used anywhere? One example that I can think of is Reflector telescope (which seems like the reverse of the described process), but would actual microscopes use such things? The Uglymancer 01:23, 26 October 2006 (UTC)

As far as I know, no microscope uses reflection to increase magnification, but I could be wrong. I do know that binoculars use reflection in part of the optical path in order to have a long light path contained within a short physical housing. See the article on porro prism and the article on binoculars for more. 192.168.1.1 6:50, 24 Rocktober 2006 (PST)

Is it possible to magnify things reflectively, and is it used anywhere? -- youbetcha, see [14] Dallas67 04:39, 26 October 2006 (UTC)

Help with relativity

I am trying to help my daughter with all of her homework and we are never going to be finished with all of it, so I need alittle help. One of her questions that we both can't figure out is,"You have learned about the Newton's concepts of motion, force and energy, and Einstein's theories of special and general relativity add a new twist as how the working s of nature are perceived. Comment on a feature of one of the theories that interests you. Use your imagination and come up with an idea how it might have real life application or even used in a science fiction story."Please help she really needs this grade. Every time you all have always hit the nail on the head with the questions. THANKS!!!!!!!!— Preceding unsigned comment added by 205.188.116.74 (talk)

You want us to tell your daughter what interests her and use her imagination? I'm not sure we can help with this part. Look at the articles on astronomy, generaly relativity, special relativity and newtonian physics. There are plenty of applications from astronomy to medicine. --Tbeatty 02:50, 26 October 2006 (UTC)

Since this question requires imagination, we can't exactly help without practically completing it for you. Try the articles on Classical mechanics, Special relativity and General relativity if you need some reading material. -- Consumed Crustacean (talk) 02:53, 26 October 2006 (UTC)

Because we're all a bunch of guys that don't have any imagination.X [Mac Davis] (SUPERDESK|Help me improve) 07:10, 26 October 2006 (UTC)

Nah, we have active (some would say over-active) imaginations. But even when we're pondering physics, I doubt we're imagining the same things as someone who's had the same level of science and worldly experience and been in the same science class as your daughter. DMacks 08:49, 26 October 2006 (UTC)

Or her teacher. Pffst, stupid assignment. —Bromskloss 10:01, 26 October 2006 (UTC)

I wouldn't say it's a stupid question. It's perhaps not really a physics question but it is IMHO a good question. It requires one to actually think and understand the concepts rather then just parroting something which is good since too many students can only parrot. No one said your answer has to be the same as the teachers or anyone else's. Provided you demonstrate an actual understanding of the concepts and an ability to think, I would assume you would be given your marks. This isn't a right or wrong answer question... BTW we do have imaginations. I'm thinking how old is your daugther? Over the age of consent I hope? I'm imagining what she looks like...... Er you probably don't want to hear the rest. (Okay I made this up but I'm sure there are some wikipedians thinking it). Nil Einne 13:49, 26 October 2006 (UTC)

BTW I got this from the reference desk a while back "it would be really kewl if your parents went on a trip to a nearby blackhole for 2 weeks then you will be 20 years older than your parents when they return --RedStaR 20:55, 27 September 2006 (UTC)". While it's talking about black holes, in actual fact if your parents were travelling at or close to the speed of the light they could easily end up younger then you as time would be travelling much slower for them (see Time dilation). This obviously has implications for SF... Nil Einne 13:48, 26 October 2006 (UTC)

How would helping high school children with homework, help them when they have to write their exam all on their own? It's the same with study groups - you don't write exams in groups. Also, if the answer requires imagination, the only way to develop imagination is 'try it yourself' and not ask for help. As Einstein added the fourth dimension into Newton's classical laws of physics, perhaps your daughter should do some research on time travel or time paradoxes - right into the realm of science fiction where imagination has no boundary. Sandman30s 12:02, 26 October 2006 (UTC)

Hmm, time travel, black holes as portals thru time and space, parallel dimensions...I'm sure something interesting is out there. StuRat 00:11, 27 October 2006 (UTC)

chemical reactions

how could i know what chemical products can be produced in a reaction simply by knowing the reactants (and apart from memorizing them)? for example, for the thermal decomposition of hydrated copper (ii) sulphate crystals...is sulphuric acid formed and copper oxide and hydrogen gas? how can i tell, simply by looking at it?

One important thing to do is to write down a reaction for whatever you propose and see if it can be balanced. If you can't make it balance, it's probably not something that happens:) After that, it comes down to proposing lots of likely things. That means knowing the general kinds of reactions that happen, not memorizing a lot of specifics. For example, you perhaps know that many acids are compounds that can release H+ in solution, and you can probably even recognize many such compounds by their name or formula without explicitly memorizing every acidic compound explicitly. For the situation here, here's a hint: many hydrates can undergo a common reaction by virtue of their being hydrates. DMacks 08:41, 26 October 2006 (UTC)

Well, apart from some simple and relatively well-known cases, as in classic inorganic chemistry, you can't actually tell exactly how stuff is going to react. That's what chemists know and what they're needed for. But the knowledge itself doesn't follow any simple rule. It's a mix of stuff learned by heart (and generalizing it) simple but approximate rules and intuition, more or less. It's basically a large part of what chemistry is all about, so I can't really suggest more than just "learn chemistry". --BluePlatypus 14:08, 26 October 2006 (UTC)

In the example you mention, a small amount of chemical experience will suggest that the water in the crystals is not very strongly held there, whereas the other ionic bonds in the copper sulphate are much stronger. So heating hydrated copper(II) sulphate (at a moderate temperature, anyway) will cause there to be a thermal decomposition reaction, merely producing steam and a white solid known as anhydrous copper sulphate. If hydrogen was going to be given off, it would require there to be a redox reaction, and simply heating a solid isn't likely to do this. I'm afraid that experience with experiments will enable you to predict the outcome of unfamiliar reactions much more easily. --G N Frykman 22:04, 26 October 2006 (UTC)

Geography

I have some topics on which i am not getting any information. i have searched a lot but not getting what i need, so i need ur help for this.

And your specific question would be .... ??? JackofOz 10:53, 26 October 2006 (UTC)

i have some topics on which i am not getting any information. they havee asked to choose any one realms of the earth.i have taken earth. then they have asked to find

• the diversity of enviroment that exists in the world which supports life.
• ollect stories,legends,festivals,poetry,sayings,rituals,associated to water
• write a report on how mans interaction with nature has resulted in different hazardous situation such as:- deforestation and soil erosion causing floods and droughts water scarcity in rural and urban areas.

if u would just tell me from where i can get this information and the sites i would really be gratefull to you. thx.

This is a very large research project. Looks like dozens of hours of work, and 20-40 pages. I would take time to invest in research techniques, such as using Google, or libraries. Good luck! --Zeizmic 11:44, 26 October 2006 (UTC)

Or Wikipedia of course: biodiversity, water, deforestation, soil erosion, flood and drought might be good starting points (haven't looked at them myself - that's your job). DirkvdM 14:27, 26 October 2006 (UTC)

Derivation and Use of Clausius-Clapeyron relation

Hi everyone. From the article Clausius-Clapeyron relation, I'm confusing about its derivation. It says that

Along the coexistence curve, we also have dμI = dμII.  

And after that we use the $d\mu =-sdT+vdP$ relation to give the final formula. My question is that we use two points in the coexistence (phase-equilibrium) curve to derive the formula. Those two points describe the same situations where there are two phase appeared in equilibrium in the system. Hence, the Clausius-Clapeyron equation should be used only for describing a change between two points along the phase-equilibrium curve.

But commonly we use it to refer about latent heat for describing phase transition. We try to describe two situations between a point at equilibrium (two phase) and a point outside the equilibrium curve (only one phase). So why is the equation valid in this case? I know I'm missing some important concept here. Thanks everyone for your attention. -- 131.111.164.228 11:13, 26 October 2006 (UTC)

It's derived at equillibrium between the two phases and describes the relation between the latent heat of the phase change and the associated changes in temperature, pressure and volume. The latent heat of the phase change is what it's all about. If you want to study the change between states that aren't in equillibrium, then you set up a thermodynamic cycle. --BluePlatypus 14:00, 26 October 2006 (UTC)

As far as I know, the Clausius-Clapeyron equation gives an approximation to the slope of the coexistence curve--that's it. ("Equillibrium" is a tricky word because thermodynamic equillibrium is a separate concept from phase equillibrium.) It says nothing about states of single phase, nor does it even describe the coexistence curve properly--firstly, it's a linear equation (which most coexistence curves are not); secondly, it only describes the transition between two out of three possible phases. In other words, I am questioning the validity of your last paragraph. Ckerr

It is not an approximation at all. It is exact. Nor is it a linear equation. It's a PDE. Now, if you chose to integrate that as if it wasn't, which some people certainly do, then it becomes an approximation. But it's not one present in the equation itself. --BluePlatypus 21:00, 26 October 2006 (UTC)

The points I and II are actually the same point on a PT diagram; they are different points on a VT, or PS, or VS diagrams. You do not take two different points on a melting curve on a PT diagram, you just take one point (which gives you the temperature at which your element would melt under given pressure, provided the pressure does not change in the process). Now you would like to know what is the melting curve slope at that point. Here the Clausius-Clapeyron equation becomes useful. You see, that single point in a PT diagram becomes an infinite number of points when you go to the VT diagram. Indeed, under given P and T, when you are on the melting curve, you can vary the fraction of phase I in the mixture continuously between 0 and 100%. This changes V (as the specific volumes of the two phases differ, generally speaking), without changing either P or T or mju (but changing S). The Clausius-Clapeyron equation is then derived from the fact that mju stays constant. The two points used in the derivation are at the same P and T; simply, one is 100% phase I, 0% phase II; and the second one is 0% phase I, 100% phase II. The slope is thus defined at a point (PT) proper, not at two close points. Hope this helps. Dr_Dima

Expert In Opacity Needed

Hey. The article Opacity (optics) is in need of a rewrite from an expert. I'm not one. However, if anyone has any assistance that they can render, it would be appreciated! Scalene^{•UserPage•Talk•Contributions•Biography•} 11:34, 26 October 2006 (UTC)

• You could always post a message on Wikipedia talk:WikiProject Physics. They may be able to help you. – ClockworkSoul 13:51, 26 October 2006 (UTC)

I rewrote it, although I'm not claiming it's complete (or that I'm an expert). Feel free to remove the help tags if I've done a good job with it. I also proposed a merge, if anyone's interested in helping with that. --Tardis 15:33, 26 October 2006 (UTC)

Added a paragraph. Some important things are still missing (self-absorption, relation to line profiles, absorption mechanisms, etc...). Which level are we aiming at: high school? undergraduates? experts in adjacent fields? --Dr_Dima

All levels. A Wikipedia article should start out with an intro that those with the least background can understand, then build up to the most complex theory, at the end. StuRat 23:50, 26 October 2006 (UTC)

Eiinstein's theories

I am trying to solve a problem but I am stumped, please help. How can you add a new twist as how the workings of nature are perceived when using Einstein's theories? and how might it have real life applications? Thanks!!!

—The preceding unsigned comment was added by 205.188.116.74 (talk) at 00:58, 27 October 2006.

Your question is vague - Albert Einstein worked on many theories throughout his life, which are you referring to? However, in any case, you should do your own homework (see the top of this page). — QuantumEleven 13:07, 26 October 2006 (UTC)

See the same question above. The user is simply repeating the question with less info thinking he or she can con us in to helping. However our answer is the same Nil Einne 13:41, 26 October 2006 (UTC)

A good try though ! If this is a different user trying to get the homework done from us, see Wikipedia:Reference_desk/Science#Help_with_relativity -- Wikicheng 13:46, 26 October 2006 (UTC

I am doing my own homework, and I am not pertending to be someone else in order to get you to help. All I was asking is to help out, but as usual you have one or two of you trying to be smart about a question. I will not ask another question from you and the donations that come from the Miller Foundation will also be ceased. Thanks anyway.

I sincerely hope that until you grow up you will not be allowed to handle any significant amount of money. Cryonic Mammoth 16:52, 26 October 2006 (UTC)

This question I actually feel negatively towards. It evokes some anger response in me. That's scary. Please try before you ask here. This is a very easy question, and we would answer it, but I know I wouldn't feel like I answered it much at all without at least a page. X [Mac Davis] (SUPERDESK|Help me improve) 04:28, 27 October 2006 (UTC)

If you don't mind my asking, to exactly which Miller Foundation are you referring, and over how much of their funding do you have direct control? There's the Miller Foundation, the Brittaney Miller Foundation, the Rush-Miller Foundation... [15][16] Try to be more explicit in your vague, unsubstantiated threats. Black Carrot 21:06, 27 October 2006 (UTC)

research project

i have to find info on sampling and randomisation but i cannot find anything on representitive sample any search engine i use comes back with no information

Please sign your posts and don't add a space as the first character because it screws up text. I suggest you use a different search engine. Google finds quite a bit of stuff with representitive sample. Of course, it helps a LOT if you spell it right and search for representative sample instead but Google will usually make you aware when you spell a word wrong (and as I said you get useful stuff however you spell it). Alternatively use a spell checker. BTW, sampling on Google also give a lot of useful links as does randomisation and the alternative (predominantly US) spelling randomization. So really I don't know what search engines you tried but you should add google to your list. I also found useful wikipedia articles with these searches and using the wikipedia search would probably find the same article... Nil Einne 14:15, 26 October 2006 (UTC)

Randomisation? DirkvdM 14:30, 26 October 2006 (UTC)

Well actually Sampling (statistics) is probably what the above reader needs, but I was trying to encourage him/her to actually search Nil Einne 14:46, 26 October 2006 (UTC)

Focus and focal point

Quick question for the physics people: Is the focal point of a parabolic mirror located at the same point as the geometric focus of the parabola? Thanks, Zagalejo 14:18, 26 October 2006 (UTC)

Yes. Virogtheconq 14:39, 26 October 2006 (UTC)

It's not a proof, but it may help to remember that each point on a parabola is as far from the focus as from the directrix; it's therefore reasonable that the image of the focus in a parabolic mirror would be the directrix (many different images, in fact, from each point on the mirror). Since all the shortest-distance (perpendicular) lines from the directrix are parallel, light emitted from the focus is redirected into a parallel beam (the definition of the focal point). (It makes no real difference whether it's truly parabolic or is a circular paraboloid, except that in the former case the focus is a line, not a point.) --Tardis 15:06, 26 October 2006 (UTC)

Cool, thanks all. Zagalejo 23:41, 26 October 2006 (UTC)

Blind Dreams

What do people dream about if they have been blind all their lives? Is it purely sounds and textures? Paul venter 14:29, 26 October 2006 (UTC)

Good one. If the visual cortex is intact, I suppose they will have visual aspects to their dreams. But if it is never used (for lack of input), it might degenerate. Don't know, though. Of course, this would also depend on the cause of the blindness - I just assumed it was in the eyes, but if the visual cortex were deficient from birth they could never imagine colour, I suppose. DirkvdM 14:35, 26 October 2006 (UTC)

[17] might be useful and [18] both of which I found from [19] (most alternatives also work). Short answer - usually yes if they're not congenitially blind, probably not if they are. Of course, although I haven't read the 2004 paper, I'm somewhat skeptical whether you could establish whether a congenitially blind person has visual dreams. Without any knowledge of what vision is like, how will they know if they are seeing something? Food for thought. Nil Einne 14:53, 26 October 2006 (UTC)

If they "knew" what shapes things were without touching them, that would be a way to know they were seeing them. There was an interesting sci-fi book where almost everyone was blind. One girl could see, so knew about things before she felt them, and everyone else thought she must be psychic. StuRat 23:43, 26 October 2006 (UTC)

One could check for activity in the visual cortex. That doesn't necessarily mean that they see the way we do, but of course the same goes for anyone else. I only assume that other people see things roughly the way I do (in a literal sense, I mean). That when I see the colour red, they will have a similar sensation. But of course I can never really know that. DirkvdM 09:38, 27 October 2006 (UTC)

You know, by a common definition of "psychic" (aka extrasensory perception), she would be. She has a sense they don't have, don't understand, and can't really even imagine. I've heard people claim that claivoyance is the "sixth sense", one with a corresponding sensory organ, which we just haven't tracked down yet. Of course, it'd be more than the sixth, even among the traditional senses, but the point is the same. Black Carrot 20:51, 27 October 2006 (UTC)

And, as a matter of fact, you can know that. Not yet, sure, but once we've actually got some clue how the brain works (cross your fingers), it should be fairly straightforward to demonstrate whether or not we process basic visual information the same. For instance, the retina has been thoroughly studied, and at least one stage (the photoreceptors themselves) has a fairly conclusive answer: there's quite a bit of similarity in the distributions of red, green, and blue photoreceptors from person to person, but some variation, which may or may not be accounted for by the brain itself. Black Carrot 20:55, 27 October 2006 (UTC)

Vitrectomy aftermath

I assume the vitreous humor regrows after a Vitrectomy, but does anyone know how long it takes? My guess is the fluid would come back within a day or two, but the fibrous network may take some time after that - does it require leaving some of the humor behind as a seed, or will it all come back naturally? Virogtheconq 14:47, 26 October 2006 (UTC)

The vitreous does not regenerate spontaneously. To maintain the proper shape of the eye, chemically stable, optically clear, sterile viscous fluid is infused in its place. — Preceding unsigned comment added by Jodahy (talk • contribs)

The article also says that a gas is used and diffuses out gradually, meaning that eventually the humor returns. Obviously that won't happen spontaneously, but I'm interested in the timescale on which it happens. Virogtheconq 13:26, 27 October 2006 (UTC)

s and d orbitals

What does the s and d areas in the peroidic table have to do with orbital notation? 216.253.128.29 16:10, 26 October 2006 (UTC)nicholassayshi

• This picture might help you out a little bit.

The orbital names are s,p,d,f- in that order. On the periodic table, each atom is written with its electron configuration, showing which electron orbitals are filled.

For more info, look at the article on Electron configuration. It is explained there in more detail. Laurən^whisper 16:25, 26 October 2006 (UTC)

• A little more specific info, spdf designate the different shapes of the orbitals, also. Laurən^whisper 19:15, 26 October 2006 (UTC)

I also am trying to understand elctron configuration in orbitals. How does that image present electrons relatve to the nucleus? Are those the varied directions the electrons will appear from that orbital (with the nucleus being in the center). or is that a visual representation of one electron? More simply put, I am confused about the visual representaion of electron(s) and/or nucleus in those images of the orbitals. 69.150.209.15 19:22, 26 October 2006 (UTC)

Those are representations of the 3D region where an electron in a given orbital is likely to be found around a centrally-located nucleus. We can't actually locate a specific electron at a specific position, and electrons really are free to be located anywhere at all, even miles away. But we can talk about, over time, the where they "usually" are, a "probability density". So an electron in an s orbital is generally found in a spherically-symmetric region around a nucleus, whereas an electron in a p orbital is generally found in a dumbell-shaped region along a certain axis through the nucleus. DMacks 19:40, 26 October 2006 (UTC)

Basically, that happy little diagram where the electrons moved around the nucleus like planets around the sun was wrong. It's just a really simple way of showing it. And for the rest, DMacks pretty much has it covered. --AstoVidatu 21:55, 26 October 2006 (UTC)

I seem to remember from college chemistry that s,p,d and f stand for "secondary, primary, diffuse, and fine," perhaps from the appearance of spectral lines. So what is g?Edison 00:01, 27 October 2006 (UTC)

"g" is the letter after "f":) No, seriously...see Electron shell#Subshells. DMacks 01:42, 27 October 2006 (UTC)

Warm-bloodedness in birds and mammals.

Did warm-bloodedness evolve in a common ancestor of birds and mammals (was the most recent common ancestor of birds and mammals warm-blooded), or did it evolve independantly in the two groups? Would it be possible to determine this by comparing the mechanisms birds and mammals use to maintain thermal homeostasis? grendel|khan 17:07, 26 October 2006 (UTC)

Good question. There are many cases of convergent and parallel evolution, but our articles don't list this one. Cryonic Mammoth 17:14, 26 October 2006 (UTC)

Good question indeed. Looking up "endothermy evolution birds mammals" in google gives plenty of good hits. There seems to be quite a bit of argument going on about the details of warm-bloodedness evolution, but most seem to agree that the primary thermoregulation mechanisms are already present in reptiles. It's just the metabolism rate in reptiles that's not high enough. Dementios

Hmm... I'm not sure about birds and mammals, but homeothermy of a degree is found in fish (particualrly some kinds of Tuna and Lamniform sharks (see Salmon shark)). This is believed to have arisen independentally. --TeaDrinker 19:58, 26 October 2006 (UTC)

I think the current concensus is that they evolved it seperately (at least that is what we are being taught in uni). It is unknown, though seems to be actively argued, whether dinosaurs were warm blooded. However, I think mammals diverged from reptiles just after the amphibians, so there is a big gap there. --liquidGhoul 22:25, 26 October 2006 (UTC)

I was taught that they were not. That a lot of the similarities between birds and mammals (like the heart for example) are covergent evolution. Common ancester between birds and mammals go as far back as the reptiles, so i'd think not. With fish, it's defintely convergent evolution. Things like Tuna and sharks are slightly endothermic for completely different reasons. Where as things like whales are endothermic because they're not fish at all =). --`/aksha 01:50, 27 October 2006 (UTC)

Colour of semen

I have noticed my semen is a little less opaque and yellower than that of others. Does this mean something about sperm count, or tell anything else about my health? I have not yet tried to get my wife pregnant but we are considering that before the end of the year. I've never pointed that out and I strongly doubt she noticed it. Please let me know if this is a bad thing because I'll need to bring it up.

First, see a doctor for medical advice. Second, semen takes on a yellow tint as you age. It also turns yellow if you haven't had an orgasm in a long time. It also turns yellowish with a high sperm count. It also turns yellow in the presence of many common infections. So, yellow semen is just a symptom. You need to see a doctor to figure out what the cause of the symptom is. --Kainaw ^(talk) 19:02, 26 October 2006 (UTC)

Check your lighting, it easily appears yellow sometimes if it is in a "warm" color light. X [Mac Davis] (SUPERDESK|Help me improve) 04:51, 27 October 2006 (UTC)

Plane Crash

Which seats in a big airliner do you think are safer depending on the different types of crashes? It does happen quite often that a plane crashes and it is announced that "189 people died, and 3 survived" or sentences of that sort they never specify where the lucky ones were sitting. I was thinking more towards the tail of the plane, dont know why, it seems stronger somewhat but then that last Kentucky one only the co-pilote got dragged out of the burning plane by the fire brigade if I remember correctly. Any thoughts or statistics? Thank you. Keria 19:55, 26 October 2006 (UTC)

IIRC, you want to sit either near the tail, since that part usually absorbs the least amount of shock on impact, or you want to be around the wings, since that's the strongest part of the airframe. --BluePlatypus 20:53, 26 October 2006 (UTC)

Where is the fuel tank usually located? Might want to avoid sitting on top of that. --Kurt Shaped Box 23:02, 26 October 2006 (UTC)

I have heard, albeit not from a source that would know directly, that most deaths in plane crashes are from smoke inhalation and fire. Thus the best places to sit might be near the exits. Tuckerekcut 23:07, 26 October 2006 (UTC)

I have heard that the safest is by the wings, I believe from documentaries on National Geographic etc. It is both the strongest part of the plane as well as right by the exits. --Wirbelwindヴィルヴェルヴィント (talk) 23:30, 26 October 2006 (UTC)

Since you asked for statistics, I'd like to point out that since the odds of you dying in an airplane crash are lower than 1 in 5000 - over your entire lifetime, and your odds of dying on any given trip are roughly 1 in 6 million, your best bet in choosing a seat is to look at something like SeatGuru to choose the most comfortable seat -- particularly since your odds of being uncomfortable on any given flight approach 1 in 1. --ByeByeBaby 00:01, 27 October 2006 (UTC)

FYI the fuel tanks in most commercial airliners are in the wings. Larger aircraft such as the Boeing 747 also have tanks in the lower half of the fuselage. 192.168.1.1 5:21PM, 26 Rocktober 2006 (PST)

One look at controlled impact demonstration should change your mind about sitting above the wings. Xcomradex 01:41, 27 October 2006 (UTC)

Heh, it seems to be a total mess anyway, no matter where you sit. Hmm, all the passengers seem to be asleep, and the little one has apparently turned around, planting their face in the seat. :-) —Bromskloss 12:27, 27 October 2006 (UTC)

No matter where you sit, the inside of the plane is likely to be a mess after any impact, since it's not designed to handle the same load conditions the structure is. I don't think it really matters where you'll be sitting since everything's going to get tossed around anyways - in that case, it'd probably be better to be seated close to the emergency exits, so avoid the previously-mentioned asphyxiation scenario. Virogtheconq 01:55, 27 October 2006 (UTC)

When we start falling I'll go lock myself in the toilets at the back. Thank you. Keria 08:55, 27 October 2006 (UTC)

There was a BBC documentary on this recently and the final conclusion someone drew was "We don't really know" because every plane crash is different. So those shots Xcomradex linked to are no indication at all. But two considerations were that near the wings the structure of the plane is extra reinforced and that it helps to sit near an exit. Especially that last bit seemed to be important. Also, bend forward before the plane crashes, so you won't slam into seat before you quite as hard, and try to immobilise your limbs so they won't go flapping about (your muscles can't possibly couteract the forces excerted on your body by a plane crash). Maybe wrap your arms aroun your legs. Oh, and if you land in water, inflate the life jacket at the moment you leave the plane, not before because it will hinder your movements in the melee of people scrambling over each other after the crash - the main reason to sit near an exit. DirkvdM 10:06, 27 October 2006 (UTC)

I don't have it handy, but a report I read from the FAA some time back said that sitting near an exit didn't guarantee you'd be able to use it. During even a mild crash, the fuselage telescopes slightly, resulting in compression forces which made it impossible to open the exits. One test showed that they had to tow the aircraft body forward for some distance to fully relieve the stresses and enable the exits to open. Additionally, in a severe crash, the fuselage will rupture in many places, creating new exits. 192.168.1.1 8:46, 27 Rocktober 2006 (PST)

The Science magazine?

Could anyone tell me how can I get the issues of the Science magazine, please? I live in Alexandria in northern Egypt.

--62.139.172.44 21:24, 26 October 2006 (UTC)

Go here for information on ordering an individual article/issue, and here to get information on subscribing. --AstoVidatu 21:59, 26 October 2006 (UTC)

Personal print subscriptions at $139 but digital subscriptions are only $99 and may be a much better deal oveseas to reduce shipping costs, delays, and losses. Most American and European universities and hospitals pay for free online access to Science at [[20]] for all students and faculty. If you belong to a school or similar institution with a library, ask the librarian if they have access. Another possibility would be to search online for American library associations that send duplicate copies of scientific and medical journals overseas to poorer institutions, although you may not get complete sets and the issues may be months or a year old. alteripse 23:38, 26 October 2006 (UTC)

Well, if you go to a library, you might just as well read the paper issue there. :) That can be any major public library. And surely, Alexandria must have a good library. DirkvdM 10:11, 27 October 2006 (UTC)

Basic Physics: Force Question

A car and driver at m=3,000lb total moves at exactly v=60mph along a level, straight highway heading west to Vegas for five minutes. Is it true that during that time, the car has no west-bound force (f=m*a), because its acceleration is zero? Seems strange if that's true. --12.104.14.109 22:39, 26 October 2006 (UTC)

Yes it's true that the total force is zero. However there will still be forces acting on it. Friction will act eastwards so as to retard (slow down) the motion. Therefore the engine will have to provide a force to overcome this. These forces are equal and opposite, so the add up to zero. Theresa Knott | Taste the Korn 22:51, 26 October 2006 (UTC)

How can the total force be zero? The car is travelling westward at 60 mph. If the engine's power output exactly matches the force of friction, than the car won't go anywhere. The engine has to overcome friction, and move the car. (Maybe I'm missing something obvious here--if that's the case, please tell me!) --Bowlhover 04:11, 27 October 2006 (UTC)

Oh yes, once the car is moving, it only needs to overcome friction to maintain its speed. It only needs to accelerate at the very beginning of the journey. --Bowlhover 04:16, 27 October 2006 (UTC)

In physics terms, net force --> net acceleration through Newton's second law, F=m*a. If the car is moving at constant velocity, there is no acceleration. If there is no acceleration, there is no total (or net) force. --M1ss1ontomars2k4 ^{(T | C | @)} 04:24, 27 October 2006 (UTC)

You are missing Newton's first law of motion. If it is travelling at 60 mph, with no friction, it will continue to travel at 60 mph forever till another force acts upon it. Thus, to maintain speed, engines have to put enough force to cancel out friction (including the air). --Wirbelwindヴィルヴェルヴィント (talk) 05:24, 27 October 2006 (UTC)

You are probably getting confused with kinetic energy, which is very much dependend on the mass and velocity. --Wirbelwindヴィルヴェルヴィント (talk) 23:34, 26 October 2006 (UTC)

Could be a trick question involving the earth's rotation. A toilet in a 3,000 lb RV still flushes counterclockwise when it's moving at 60 mph. It is a Coriolis force that causes the rotation. --Tbeatty 03:04, 27 October 2006 (UTC)

Huh? What does this have to do with Earth's rotation? Also, toilets definitely do not flush counterclockwise because of the Coriolis effect. See http://www.snopes.com/science/coriolis.htm. Even dropping a feather into the toilet will affect the water's velocity thousands of times more strongly than Earth's rotation can. --Bowlhover 04:11, 27 October 2006 (UTC)

October 27

Where to Purchase Digestive Enzymes

I would appreciate if anyone would know where I could purchase these digestive enzymes:

Papain (Papaya), Bromelain (Pineapple), Ficin (Figs) and Actinidin (Kiwi). I am looking for a tablet or powdered form that is mostly the enzyme and tthe concentration for each enzyme is about the same, for comparison.

The problem I am finding is that the Health Stores only carry Papain and Bromelain and some of the biochemical companies sell only industrial size.

Would any universities carry them?

Thank you.

JDC

What country are you in? Are you at school? When i worked in a school lab we used to get most of our enzymes from normal school suppliers. SigmaAldrich carry pretty much everything but they will not sell to the public :-( Theresa Knott | Taste the Korn 00:14, 27 October 2006 (UTC)

The obvious question is: Why not eat the actual fruit to get all the good stuff, instead of hoping that whatever powder they give you actually contains what they claim ? StuRat 03:29, 27 October 2006 (UTC)

Pectodictyon

What is this genus (of algae, apparently), and why aren't any descriptions of it available online? NeonMerlin 02:17, 27 October 2006 (UTC)

• Well, it's a genus within the family Hydrodictyaceae. – ClockworkSoul 04:46, 27 October 2006 (UTC)

Airships

I was reading the article on airships and finally made it to the artile discussing Orbital or high altitude airships. I was wondering if it is possible for a ballon or airship design to exist in a vacum, wouldn't it explode? Also I read about JP areospace I think they have the right idea if it's possible but the ion drive is a bit farout. Is it possible with an airship in airless space to be driven with a rocket?67.126.141.80 04:44, 27 October 2006 (UTC)

An airship in a vacuum wouldn't explode (unless it was already close to exploding in air), but it wouldn't provide any lifting power. It would fall like a rock. How do you think a balloon works? Here's the relevant part from the first paragraph of the Airship article: ...primarily by means of a cavity (usually quite large) filled with a gas of lesser density than the surrounding atmosphere. If there is no surrounding atmosphere, it can't possibly work. —Keenan Pepper 05:02, 27 October 2006 (UTC)

A balloon can certainly exist in a vacuum: for example, the Echo satellites were balloons. It simply has to be constructed of a material that can withstand the temperatures it will encounter, which are likely to vary more in outer space than in the atmosphere. It's true that the same amount of gas inside will exert a stronger pressure on the balloon when it's in vacuum, and that could make it explode, but the simple solution to this is to use a smaller amount of gas inside.

Yes, you could drive a balloon in space by attaching it to a rocket, or to an ion drive. But it would not be functioning as an airship, because an airship floats in the air and in space it would not be floating on anything. On the other hand, if it was in orbit, it wouldn't need to.

--Anonymous, 05:05 UTC, October 27.

What? How could it possibly float if there is no air around it. No air is less dense than anything. --liquidGhoul 05:11, 27 October 2006 (UTC)

An airship in a vacuum would feel a greater amount of pressure on it than in an atmosphere, but good design will keep that under control. Bigelow Aerospace has successfully deployed some prototypes in orbit of inflatable modules (ultimately) designed for use in human-habitable stations, so it's quite doable. As to whether or not it would still qualify as an airship, that's a question of semantics, but it wouldn't get any sort of power from its internal gas - it would have to use a rocket or some traditional means of space propulsion to move. Virogtheconq 06:37, 27 October 2006 (UTC)

See Echo satellite for an article about early communication satellites which were giant balloons in space. Edison 12:27, 27 October 2006 (UTC)

composite materials

I need to do a Chemistry report and presentation. Hence, I need info about the meaning of composite materials, examples and components of composite materials, comparing and contrasting properties of composite materials, and justifying the properties of composite materials. If the information is received earlier, it would be better. Thank you. --61.6.47.6 06:24, 27 October 2006 (UTC)

Have you tried looking at composite material? It has everything you need right there. Virogtheconq 06:31, 27 October 2006 (UTC)

Sexual Dysfunction

Is there a cure for sexual dysfunction? How to solve premature ejaculation in males? What are the long term side effects of it? The male patient is 23 yrs old and has symptoms of the above? How long does one generally manintain his virginity? How does one define a virgin? Advise...

Although we are lucky enough to have several medical professionals who post to the boards, we discourage questions that require medical speculation or advice. After you read premature ejaculation, you might want to have 'the patient' contact a medical professional. Anchoress 09:08, 27 October 2006 (UTC)

How long can one maintain his sex drive? Till what age particularly the males?

See also Virgin, Sexual dysfunction, and Sex drive. Many people, male and female, retain a certain libido through old age, although typically diminished compared to when they were teenagers.  --Lambiam^Talk 10:51, 27 October 2006 (UTC)

There's a saying about male potency: 20 years old, triweekly. 50 years old, try weekly. 70 years old, try weakly. Edison 12:30, 27 October 2006 (UTC)

On loveline Dr. Drew sometimes talks about this premature ejaculation medicine that is in the works... something like an extremely short acting prozac. Xcfrommars 20:24, 27 October 2006 (UTC)

Communication Engineering

What is the difference between noise and distortion in communication?

Have you looked at our articles Noise and Distortion? In general, noise is a disturbance that is added to the signal, like hiss on an old grammophone record. Distortion can be any change in the signal shape, such as when a sound is muffled (high-frequency cut-off) or you turn up an amplifier too much.  --Lambiam^Talk 10:29, 27 October 2006 (UTC)

Simply put, distortion means a bad signal, while noise means no signal (or a random signal if you wish). Turn on the tv and take out the cable. The 'snow' you see is noise. DirkvdM 11:29, 27 October 2006 (UTC)

Ignore the above; it is noise. Actually "noise" can be used with two meanings: (1) additive disturbances, typically undesirable because they interfere with a proper transmission of the signal; (2) the same for a "zero" signal, so all that is left is "pure" noise.  --Lambiam^Talk 14:29, 27 October 2006 (UTC)

Electrical noise can be defined as an unwanted signal which is always present in a communication system. its presence tends to impede the reception of the wanted signal and is usually the limiting factor in its detection.

#

from Noise, F.R Connor, Pub. Edward Arnold 1973. ISBN 0 7131 3306 6. Chapter 1 para 1 --Light current 19:10, 27 October 2006 (UTC)

high frequency gravitational waves truth or myth

I have read about high frequency gravitational waves that should in theory have a number of effects such as propulsion and peterbation of objects, I have found a few webpages that deal with the subject that seem legitimate http://www.iop.org/EJ/abstract/0264-9381/22/10/046 http://www.iop.org/EJ/article/0264-9381/22/10/046/cqg5_10_046.pdf This one is from an institute used to study gravitational waves called LIGO http://www.ligo.caltech.edu/docs/G/G030067-00/G030067-00.ppt So are these waves a myth, a theory or can we just not make them yet? Rupert

Have you looked at Gravitational wave? In theory, whenever you wiggle your nose, it will generate gravitational radiation. However, despite strenuous efforts, scientists have not yet directly observed gravitational waves, not even from binary systems with black holes or neutron stars, much less from anything we can do.  --Lambiam^Talk 10:22, 27 October 2006 (UTC)

First of all, any gravitational wave would have the effects you mention, although the higher the frequency the more noticable the effect. As Lambian mentions the logistics of us creating them prevent us. It is almost certain that they do exist, but due to the weakenss of gravity they are very hard to detect. I can't remember how LIGO looked for them, but any terrestrial attempts are futile as the effect is almost certain to be lost amongst the vibrations of the planet. There is a mission planned that will use (I think) three satellites in orbit around the Sun with lasers pointing between them. If any gravitational waves move between them they should cause a blueshift in the lasers which could be detected. I hope I've been of some help.

Colour of dreams

A question that always evokes an interesting response, if not an intelligent answer, from people that I ask :) Do you dream in colour, or monochrome? Sandman30s 14:22, 27 October 2006 (UTC)

Colour. --liquidGhoul 14:27, 27 October 2006 (UTC)

Usually colours that are as vivid or more than in reality. Sometimes I have image-less dreams, or with dim and mute, almost monochromatic colours.  --Lambiam^Talk 14:34, 27 October 2006 (UTC)

Colour. Although I read somewhere that we all dream in colour, some people are just not capable of remembering in colour. :-)) Or they were trained to believe from a young age that some (or all) people dream in b/w, and that's what they've programmed themselves to remember. Anchoress 14:41, 27 October 2006 (UTC)

Generally I dream in colour, besides the odd exception. I've had a couple of grayscale dreams, or dreams which I remember being as such, but they were in the dark where I'd expect to see little if any colour in real life. I've also had a couple extremely abstract dreams that seemed to be purely black/white (ie. white letters on a black background, nothing else). There was also one which wasn't in grayscale but was all in shades of purple. -- Consumed Crustacean (talk) 15:37, 27 October 2006 (UTC)

Canadians dream in colour, Americans in color! This was the gist of my 1 min research on this issue: Recent experimental dream studies by Kahn et al. (11) have suggested that most, if not all, dreams are experienced in color, but that memory traces of the color perceptions are "bleached" progressively after awakening through various psychic mechanisms which are as yet unclear. --Zeizmic 15:44, 27 October 2006 (UTC)

And English people. This faq has always puzzled me. Why shouldn't people dream in colour if they see in colour? What would surely be remarkable is dreaming in shades of grey (or sepia, or anything else).--Shantavira 17:21, 27 October 2006 (UTC)

Places, people, situations and words are first remembered in dreams ; colors less, smells lesser (personal research). -- DLL ^{.. T} 17:48, 27 October 2006 (UTC)

I remember seeing stuff, feeling buoyancy, the touch of the ground, and the wind, but I can't remember if what I saw was in colour or black-and-white. --Kjoonlee 18:41, 27 October 2006 (UTC)

Can't remember if what I heard was in stereo either. :( --Kjoonlee 18:42, 27 October 2006 (UTC)

Color. Black Carrot 20:35, 27 October 2006 (UTC)

Earthing/Grounding

What are the merits and demerits of using rod earthing or plate earthing in household electricity?Which one is better?amrahs 17:30, 27 October 2006 (UTC)

I'd imagine a plate would be significantly more expensive to install and may have initial settling issues but would have a much lower resistance to the general mass off earth due to its much larger contact area. Plugwash 17:41, 27 October 2006 (UTC)

If you're building a new house, I'd recommend you install a Ufer ground instead of a rod or plate ground. Ufer ground example. 192.168.1.1 11:50, 27 Rocktober 2006 (PST)

I believe this is only necessary if you are building something totally isolated from a town water system, like a farmhouse or a cottage. --Zeizmic 19:57, 27 October 2006 (UTC)

measurement by vernier

how to use vernier caliper?

Go to vernier caliper and you can see one being used to measure a coin. --Kainaw ^(talk) 18:06, 27 October 2006 (UTC)

Tooth Transplant

Is it possible to get such a thing as a tooth transplant? Would I be able to get it done on the (UK) NHS as I am 17 and suffer from enamel hypoplasia.

Yours, Christopher

Assuming it was technically feasible (which I doubt), then, If you needed more than one tooth replacing, there would be a practical problem of getting a matching set to fit, unless they were all taken from a corpse with the same size mouth as yours. However, implants I believe are possible at about £2000 per tooth. 8-).--Light current 19:27, 27 October 2006 (UTC)

I'm no orthodontist, but wouldn't it be possible for the you to get a fake tooth implant instead of the real deal? If you haven't finished puberty you're probably close, so there would be no issue with the rest of the mouth outgrowing the fake tooth. (OK actually that last part makes little sense but my suggestion stands.) Hyenaste ^(tell) 19:58, 27 October 2006 (UTC)

Walls

Do walls really need mortar? If so, why?--Light current 19:23, 27 October 2006 (UTC)

Walls don't need mortar, bricks do. But only if you want them to hold together. --BluePlatypus 19:25, 27 October 2006 (UTC)

OK do bricks/stones need mortar to make a wall and why?--Light current 19:28, 27 October 2006 (UTC)

So seagulls can't easily knock down the wall. --Zeizmic 19:50, 27 October 2006 (UTC)

Well if you have superglue, then you can use that to hold the bricks together. Otherwise, the bricks will just fall down every time there's a windstorm. --Bowlhover 19:59, 27 October 2006 (UTC)

Not true! Dry stone walls can last in wild windswept areas for centuries!--Light current 20:44, 27 October 2006 (UTC)

It all depends how massive the bricks/blocks/stones are. Plenty of walls, barns, and pyramids are built without mortar. Many single-skin walls built with mortar are actually quite easy to push over.--Shantavira 20:13, 27 October 2006 (UTC)

Mortar is just one of many ways to get blocks of stone or brick to stay together. Other methods include having overlapping pieces (like Legos) or just relying on mass and geometry to hold them together (as in Egyptian pyramids). Mortar seems to have a disadvantage that it doesn't last as long as the bricks or stones, so can shorten the life of a wall, relative to one held together by some other method. Mortar-free walls may also benefit from being able to expand and contract with changing temperatures, without building up stresses which result in cracks. Of course, anything connected to such walls also needs to be free to move, or the cracks will occur there. StuRat 20:38, 27 October 2006 (UTC)

Quite. It's certainly possible to do construction without mortar. Often such work demands much more skill from the craftsman, however. Each stone has to be carved to match the stone below. The aqueduct of Segovia is a Roman aqueduct built entirely without mortar that is nearly two thousand years old. TenOfAllTrades(talk) 20:49, 27 October 2006 (UTC)

So why do we actually use mortar in all modern masonry buildings?--Light current 20:53, 27 October 2006 (UTC)

Mass production concerns. It takes too long to assemble a wall from pieces that must be fit together like a puzzle - it's far cheaper and faster to manufacture bricks or quarry rocks and slap them together with some mortar.

Colon Cancer

I've got a vegetarian here trying to convince me that red meat can lead to colon cancer. This I've confirmed (at least, I've confirmed there exist doctors who believe it) online, but he further claims that it's caused by a buildup of actual undigested red meat in the person's colon, and that the average middle-aged (presumably American, since that's where we are) male has "several pounds of undigested red meat" in their colon. Should I be buying this? Black Carrot 19:30, 27 October 2006 (UTC)

According to Meat consumption and risk of colorectal cancer: A meta-analysis of prospective studies there is an association between red meat eating and increased risk of colon cancer. Eating 120 g/day of red meat was associated with an approximately 20-40% increased risk. --JWSchmidt 20:09, 27 October 2006 (UTC)

Yes, there is a risk, but no, that's not the reason. I've heard that said before, though, by some nutrition nut on TV, perhaps Gary Null. However, I do understand that a lack of fiber in the diet can leave some partially digested food stuck to the sides of the intestinal wall. I doubt if it's "several pounds", and this would include various foods, not just red meat. A healthy diet will include lots of fiber and minimize the consumption of meat (red and otherwise), as such meat is high in bad fats and bad cholesterol. Fish and vegetable fats and cholesterol are actually good for you, though, so eat plenty of those (like olive oil and avocados). StuRat 20:25, 27 October 2006 (UTC)

If anyone tells you your bowels are lined with undigested food, please label all past and future health and science advice from that person as absolutely worthless. Surgeons look at bowels every day. All it takes to clean you completely out is one bottle of mag sulfate. The bowels are so cleaned out you can shine a light through the walls. The obsession with whether your bowels are really moving everything through is classic American folk medicine, like the French with their livers and the Malaysians with koro. alteripse 21:30, 27 October 2006 (UTC)

the word for when stuff feels nice

hello, hope you can help, its driving me mad. what is the word for the study of when tangible objects feel nice. not in a dodgy wierdo way, but when car doors clunk well, switches switch securely, and hand tool type things are nice and heavy. my computer mouse feels plastic and rubbish; my new bottle opener is made of some grippy metal feels sort of well balanced. its not ergonomics, but is something like that............ please, thankyou, lovely people, etc simon

That was the word I was going to use. It's also "farfignuten" in German and "consay engineering" in Japanese (I have no clue how either is spelled). BTW, this question belongs on the Language Ref Desk. StuRat 20:28, 27 October 2006 (UTC)

Well engineered. Neat! Nice! 8-)--Light current 20:48, 27 October 2006 (UTC)

dynamic motion

A girl running at a constant speed of 2.3 m/s in a straight line throws a ball directly upward at 4.4 m/s. How far will she travel before the ball drops back into her hands? Ignore air friction. — Preceding unsigned comment added by 24.99.59.96 (talk)

Do your own homework. If there's a specific concept you need help grasping, we can aid you. We won't your homework questions for you, though. -- Consumed Crustacean (talk) 20:49, 27 October 2006 (UTC)

Word. Since it probably won't occur to you to politely rephrase the question in a more general form, or better yet, since it's a fairly standard physics problem, search for it yourself, here's where you can find the answer: Equations_for_a_falling_body. Black Carrot 21:10, 27 October 2006 (UTC)