Wikipedia:Reference desk/Archives/Science/2007 January 16

Welcome to the Wikipedia Science Reference Desk Archives
The page you are currently viewing is a transcluded archive page. While you can leave answers for any questions shown below, please ask new questions on one of the current reference desk pages.

January 16

Alkaline battery capacity under high load

According to Alkaline_cell, under a 1A load the capacity of an alkaline battery is 700 mAh. Are there any values for higher loads, such as 2A and 4A? --Jcmaco 00:54, 16 January 2007 (UTC)

Any battery has an optimum discharge rate for maximum ampere hour output. A ten hour rate is common. Naturally, some batteries are designed for extremely low current for extremely , such as silver oxide cells and cells used to retain memory on computer boards, while others are designed for high current output such as alkaline or lead acid cells. Uninterruptible power supplies for computers typically have a short discharge period such as 1 hour, so they demand extremely (destructively) high output from the battery, and could provide far more ampere hours if the discharge rate were less than the stated design rate. World War 2 torpedoes are a similar case where very high discharge rates for a very short while was the goal. The limiting factor is the drop in output voltage due to internal chemical effects such as polarization, or in other cases overheating and explosion could be the limiting factors, if a battery were discharged into such a high load it amounted to a direct short. An alkaline cell subject to an extremely high load would have an initial high discharge current such as 4 amps limited by its internal resistance, followed by an extremely fast drop in the voltage. This would decrease the current supplied to a resistive load. To maintain a 4 amp load from, say a D alkaline cell would require a load which started at about .375 ohms per cell per Ohm's law, where R=E/I. But when the terminal voltage dropped over a matter of seconds, the circuit resistance would have to drop as well, so at 1 volt the resistance would have to drop to .25 ohms, and at .75 volts the resistance would have to drop to .1875 ohms. The integrated amps times time under the curve would give the (severely limited) ampere hours obtained this way. Most things you would wish to operate for useful purposes(a motor, a light, an electronic circuit) would not function once the voltage dropped so severely. There is a reason a car battery is larger than the one on a handheld drill. Actual test data could be onbtained by experiment, but from the discharge curve the article links to, and extrapolating WAY beyond the data, it looks like the cell would drop to a 1.1 volt limit while supplying a 6 watt load (4 amps at initial 1.5 volts) after supplying less than 30 mAh, which would happen in maybe 30 seconds. If the current were then interrupted, the cell would recover its terminal voltage over a period of time. The result would depend on the quality and construction of the cell and would be subject to wide variation. (Milage may vary.) Edison 16:13, 16 January 2007 (UTC)

Under test, a 1.5 volt alkaline D cell when subjected to a 1.4 ampere load dropped to 1.0 volts and stayed there for 4 minutes, for what it's worth. Manufacturer's data says an alkaline D cell starts with an internal resistance of 0.2 ohms, implying a short circuit current of 7.5 amps at the first instant. Edison 06:10, 17 January 2007 (UTC)

This is not to say it failed after 4 minutes; it could have gone on for an extended additional time, per further test.Edison 17:47, 18 January 2007 (UTC)

Earth's atmosphere

What is the probably caused a major change in the composition of Earth's atmosphere? —The preceding unsigned comment was added by Reid44 (talk • contribs) 01:40, 16 January 2007 (UTC).

Sorry i don't understand the grammar here. Do you mean what can cause a major change, or what has caused? or has something caused? Major change is very subjective, I don't think there has been a MAJOR change in the composition of the earth's atmosphere at all, but the EFFECT any change is becoming more widely accepted. Vespine 03:51, 16 January 2007 (UTC)

See Atmosphere of Earth#Evolution of the Earth's atmosphere. Almost all of the oxygen in today's atmosphere was produced by cyanobacteria. --Bowlhover 05:18, 16 January 2007 (UTC)

Animals eat plants

Animals eating plants to get energy is what process?

Can you be more specific? Plants only? Or meat too? David D. (Talk) 02:15, 16 January 2007 (UTC)

Digestion. Emmett5 03:05, 16 January 2007 (UTC)

More broadly Metabolism. Vespine 03:46, 16 January 2007 (UTC)

Thats what i thought too, initially, but why ask for plants only? Why not just eating food? David D. (Talk) 05:12, 16 January 2007 (UTC)

Maybe they are looking for the word that is the opposite of "carnivorous". Rmhermen 18:11, 16 January 2007 (UTC)

How many frames per second is...

How many frames per second can the human eye perceive? How many frames per second is the actual universe? I checked the article on eye in order to find an answer to the first question but had no luck. And regarding the second question, my best guess is a Planck unit. Any help? Thanks. --Ķĩřβȳ♥ŤįɱéØ 03:33, 16 January 2007 (UTC)

It's determined by your brain's processing speed, and the simple version is between 50 FPS and 60 FPS. My own was measured at 59Hz. However, it varies depending on the types of visual patterns which are changing. Try searching the www or use Google Scholar with keywords like "flicker fusion frequency" or "temporal contrast sensitivity function." --Wjbeaty 02:37, 17 January 2007 (UTC)

Unless time can be quantized into chronons, fps_universe is infinite. For eye, I don't know, but I'm sure it has been asked before here. Here was one answered instance: [1] X [Mac Davis] (DESK|How's my driving?) 03:39, 16 January 2007 (UTC)

There is actually a pretty good article called frames per second with links to persistence of vision which has all the info. Vespine 03:42, 16 January 2007 (UTC)

60Hz! It's determined by your brain's processing speed, and the simple version is between 50 FPS and 60 FPS. My own was measured at 59Hz. However, it varies depending on the types of visual patterns which are changing. Try searching the www or use Google Scholar with keywords like "flicker fusion frequency" or "temporal contrast sensitivity function." --Wjbeaty 02:37, 17 January 2007 (UTC)

Considering that the Planck time is the smallest meaningful portion of time by current theories, the Universe would be running at 1.85486979 × 10⁴³ "frames" per second. — Kieff 07:44, 16 January 2007 (UTC)

However, "meaningful" is the key word, since things can still happen at any time. If one divided all of time into Planck time frames, that would be ok, but the processes would ignore having to be divided into frames. They are just going to keep doing what they are doing and will take up portions of frames. Also, isn't Kieff, dividing a unit of time by a unit of time? Planck seconds per second! A frame is not a unit of time is it? A frame is a picture of an instance in time that make up a flip book. No? X [Mac Davis] (DESK|How's my driving?) 16:38, 16 January 2007 (UTC)

No, I'm not. The unit here is frequency, s^-1 or Hertz. frame / second = frame × ¹/_second = frame × hertz — Kieff 23:00, 16 January 2007 (UTC)

"Frames per second" is a fairly meaningless measurement for the human eye. Your brain can see a series of images as representing motion at speeds as low as 2 fps, and can identify objects that are visible for as little as 1/200 of a second. The point at which you can no longer say if something is frame-based motion or continuous motion happens somewhere between 20 fps and 60 fps, and the point at which you can no longer tell a flickering light from a dim light is usually between 50 Hz and 60 Hz. --Carnildo 21:19, 17 January 2007 (UTC)

Drinking metal?

I remember hearing that for a certain procedure in the hospital, the patient drinks a liquid metal. Does anyone know what this procedure is? —The preceding unsigned comment was added by 24.231.205.94 (talk) 07:20, 16 January 2007 (UTC).

Mmmm... Barium

Hmm. My guess is that you're thinking of contract enhancements on MRI exams, but the element I'm thinking of is gadolinium which is not usually called a metal. Other substances are used, though. — Kieff 07:36, 16 January 2007 (UTC)

It's conceivable it's nothing more exotic than barium, which is metallic. (Because you at least drink that, as opposed to gadolinium, which is given intravenously). -Nunh-huh 07:46, 16 January 2007 (UTC)

I just found about that! Barium meal, barium enema, barium follow-through, barium swallow Wikipedia has it all! I wonder how tasty these are... apart from the enema. — Kieff 07:57, 16 January 2007 (UTC)

Tasty, they are not. Unless you snack on chalk as a special treat. - Nunh-huh 11:32, 16 January 2007 (UTC)

The taste though was not nearly as unpleasant as the feeling of the large, extremely heavy mass moving through your insides. Rmhermen 18:08, 16 January 2007 (UTC)

Speaking from personal experience, the liquid barium contrast agent I drank was a bit chalky, with an artificial vanilla flavouring added to make it a bit more palatable. Do note that technically, one isn't drinking the pure metal when these procedures are performed. For barium contrast, the liquid is a suspension of very finely powdered barium sulfate. (Pure, metallic barium is highly toxic, and not a liquid anyway.) Similarly, when gadolinium is used as a contrast agent for MRI, the metal is delivered as part of a chemical complex. In any case – as far as I know – gadolinium contrast agents are usually introduced intravenously, and not orally.

Pure, liquid, metallic mercury (often called quicksilver) has been used as a remedy in the past. (Indeed, it is still used as a folk remedy in some places.) For the record, pure elemental mercury has no legitimate medical uses (except inside thermometers and sphygmomanometers) and these 'cures' were usually harmful. TenOfAllTrades(talk) 19:48, 16 January 2007 (UTC)

Well, the use of mercury-filled bougies to dilate esophageal strictures is not entirely a thing of the past.... - Nunh-huh 22:25, 16 January 2007 (UTC)

I've heard of wacky new age types drinking colloidal metals, such as colloidal silver. Not generally recommended by the medical community though. Vespine 02:08, 17 January 2007 (UTC)

Where to buy Galinstan?

I've looked through wikipedia's Chemical Suppliers list but cannot find anywhere to buy the substance known as Galinstan. I know it is used inside certain thermometers; does anyone have any idea of a supplier of this material? —The preceding unsigned comment was added by 24.231.205.94 (talk) 07:52, 16 January 2007 (UTC).

If you only need a small amount you can order it from here (look for "Liquid Metal Alloy"). It's not cheap.  --Lambiam^Talk 08:14, 16 January 2007 (UTC)

Is this really safe? I was looking for this sort of thing for a while, but I'd still need a surface it won't wet... and money. That thing is pretty damn expensive. :o — Kieff 10:54, 16 January 2007 (UTC)

The store is run by an easily identifiable person, and I see no red flags, so yes, this is a bona fide operation. The stuff itself is also reasonably safe, although apparently corrosive[2] – I couldn't easily identify what it is it corrodes. It is also recommended not to drink large amounts of the stuff – apparently it gives rats a belly ache. Galinstan won't wet surfaces coated with gallium oxide.  --Lambiam^Talk 18:05, 16 January 2007 (UTC)

By "corrode," they might be talking about Liquid_metal_embrittlement. During LME, the liquid metal creeps along the grain boundaries between all the micro-crystals of the solid metal, turning it into powder. Mercury famously attacks aluminum in this way, and so it's hazardous to ship liquid mercury in an aircraft (see LME article for refs.) --Wjbeaty 02:26, 17 January 2007 (UTC)

Is a fully nutritious ready-to-eat paste a "bad" thing?

I've been wondering (and no, not from The Matrix), if we could eat a paste with all the nutrients we need in a day, would it be dangerous if done for an extended period of time? I'm thinking of a minimum but optimal effort for eating here, as in a single tube with everything you need, and that's it.

Could the all-too-easy approach to food damage our digestive system? What about our teeth? On a related question, would this sort of thing even be feasible, biologically, chemically and, well, economically? — Kieff 08:00, 16 January 2007 (UTC)

The following answer is a bit speculative. If your nutripaste is indeed fully nutritious, meaning it contains all substances in the right proportions we need in our food to stay healthy, why would it be a bad thing? Fiber can be included as needed. Not needing to chew might actually be better for your teeth; you still need to maintain good and regular dental hygiene. If necessary, you can masticate using chewing gum. I am not sure there is a definitive comprehensive list of all substances that are essential, nutrition-wise, so this may be somewhat hypothetical anyway, but assuming we have such a list, I think it should be technically feasible. It's not much different from making canned dog chow, or baby food for that matter. I have my doubts that there would be enough of a market to make it economically feasible.  --Lambiam^Talk 08:30, 16 January 2007 (UTC)

Well, I was thinking that lack of material could be a big problem. The paste wouldn't have much substance (with a nutrient/mass ratio so high,) perhaps even with fibers included, so it could disrupt our normal digestion process that evolved on "heavy" meals. I'm thinking we'd probably secrete excessive gastric juice and end up with liquid feces on this sort of died. Another thing, it's recommended (so I've been told) that we eat small meals every 2 to 3 hours, whereas you could theoretically eat this paste just once a day. About teeth, I was wondering if lack of any pressure and wear could degenerate and displace our teeth and gums. I guess chewing gum could find it's place for this issue. By the way, check Dilberito for something on this line of thought. — Kieff 08:39, 16 January 2007 (UTC)

Problems like gastric acid can probably be remedied with medication, etc. And I thought humans didn't evolve to eat "heavy" meals, but small, frequent meals? The problem that occurred to me is how people will know how much they need to eat, as in the problem of overweight, underweight, overindulgence, etc from using set portions of the paste. --Wirbelwindヴィルヴェルヴィント (talk) 10:05, 16 January 2007 (UTC)

I used "heavy" relatively, since the common meal is "heavier" than this paste would be. And yes, there would be different amounts of the paste for each individual, but this is a bit irrelevant to my point: could you survive well with this kind of food, and would such thing bring any consequences? — Kieff 10:23, 16 January 2007 (UTC)

If nothing else, it would probably horribly affect the mental health? TERdON 11:36, 16 January 2007 (UTC)

You don't have to eat a meal every 2 or 3 hours, frequency of meals is hotly debated but I am not sure we will ever know, or at least not for a very long time, and I think it really doesn't matter. If the paste has all the nutrients, WITH all the calories, supplemented by water then that is a quite healthy substance you got right there that I want some of! They don't need to "have" to know about how much to eat of the paste since the liver will measure your blood to tell you. This may, however, be offset by your stomach telling you it is empty. X [Mac Davis] (DESK|How's my driving?) 16:32, 16 January 2007 (UTC)

That answer seems totally unrelated to what I was talking about. What I meant was that I'd go crazy if I couldn't eat anything else than some silly paste. Quickly. TERdON 21:38, 16 January 2007 (UTC)

ISTR this was a problem with early long-duration space flights. Not craziness, but sheer boredom with food. IIRC Apollo and Skylab astronauts often started to lose their appetites simply because the food was so repetitive. Again, IIRC, on later missions several different kinds of "paste" were used, so that there was some variety, as well as non-paste foods. Grutness...wha? 00:31, 17 January 2007 (UTC)

A major problem with this seems to be that everyone needs different amounts of each nutrient, and therefore the paste wouldn't be right for quite a few people:( And most people don't just eat because they have to:( So I don't think it would really work:( And surely you would have to eat a lot of it to get enough sugar, fat and protein:)Hidden secret 7 19:04, 16 January 2007 (UTC)

There have been some good replies here, but I think some of the OP's questions remain to be answered. Could the all-too-easy approach to food damage our digestive system? No, I do not think so. The human GI tract has evolved to accept a very wide variety of foodstuffs in a wide variety of proportions. Before European contact, Inuit diet was almost 100% animal flesh. In many parts of the world, diet is 100% vegetable flesh. Once we meet the minimums for preventing nutrient deficiencies, the field is wide open. The only drawbacks become cultural ("I am an X and I always eat Y! It's my duty!") and psychological ("If I have to eat one more gob of paste I'm going to hurl!"). Neither are insurmountable.

On a related question, would this sort of thing even be feasible, biologically, chemically and, well, economically? Probably, yes, and not yet. I don't know if we've got a definitive answer as to what all we need to intake, though we're pretty sure it's a lot more complicated than the 'food pills' futurists used to talk about in the 1950s. Besides the vitamins and minerals we're familiar with, there are all kinds of neat chemical compounds (eg. flavonoids, phytosterols, etc) in our food that help us with our day. But getting a grip on what all we need is probably not beyond our grasp and as I mentioned above, we can get by on some suprising diets if we have to. By chemically, I guess you mean 'Is the manufacture of the paste possible?' Yeah, I don't see why not; we already make pills for every nutrient deficiency in the book from A to Zinc. Under our current economic situation, I don't think Panacea Paste ^tm is very viable, but there are lots of conditions where it might work - in places of famine, as emergency food during disasters, as provisions for mobile military personnel. If we're serious about colonizing the moon, our eating habits might have to shift to something quite like the paste. Matt Deres 03:17, 17 January 2007 (UTC)

This would eliminate people choosing foods to provide the nutrients they need at that time, like eating different foods when you are sick. A more extreme example is all the strange food combos pregnant women eat to supply the nutrients the fetus needs. StuRat 06:24, 17 January 2007 (UTC)

There's a muesli bar called "One Square Meal" that claims it has 1/4 of everything you need. It's made by a company called "Cookie Time" in New Zealand. Aaadddaaammm 02:57, 19 January 2007 (UTC)

Star Catalogue SO

From Talk:Star catalogue: Teegarden's star is designated SO025300.5+165258. Which catalog is called "SO"? Icek 09:09, 16 January 2007 (UTC)

No idea what SO stands for, but according to http://www.solstation.com/stars/so025300.htm, Teegarden's star has these ICRS coordinates: RA 02 h 53 min 00.5 sec, Dec. +16 degrees 52 min 58 sec. If you take all 6 numbers and put them together, you'll get 0025300.5+165258. --Bowlhover 22:59, 16 January 2007 (UTC)

SIMBAD is the usual definitive source for these things - http://simbad.u-strasbg.fr/simbad/ which refers to the star as SO J0253300.5+165258 - but does not list SO as a specific catalogue. —The preceding unsigned comment was added by Chrislintott (talk • contribs) 12:34, 17 January 2007 (UTC).

Sense Deprivation Chamber

Is the sense deprivation chamber used in Tom Clancy's The Cardinal of the Kremlin possible, and has it been done before? I expect that the deprivation of touch isn't because the subject would feel the breathing tube which is used. Thanks in advance. Crisco 1492 09:36, 16 January 2007 (UTC)

Sensory deprivation and isolation tanks are pretty old ideas. Take a look at the articles for more info. — Kieff 09:48, 16 January 2007 (UTC)

But try to avoid the results hypothesized in Altered States.

Atlant 17:33, 16 January 2007 (UTC)

Perhaps our article on the Pit of despair may assist. Rockpocket 05:36, 17 January 2007 (UTC)

Reversing caries

I read this in Dental caries:

Destroyed tooth structure does not fully regenerate, although remineralization of very small carious lesions may occur if dental hygiene is kept at optimal level.

Howcome small ones, but not large ones, can heal? —Bromskloss 09:53, 16 January 2007 (UTC)

For the same reason that falling 10 meters onto concrete is catastrophic but falling 10 centimeters is not. When it comes to damage, more is obviously worse. There's a critical threshold of decay beyond which body parts do not regenerate. Vranak

Or compare it with cuts. A small cut will heal perfectly, a large cut will heal with a nasty scar, and a huge cut may kill you. Also, bones will only heal if the two broken ends are within a certain distance of one another. StuRat 06:12, 17 January 2007 (UTC)

Oxygen Sensor

Are Oxygen sensors available in nano ranges (in terms of detection)& nanosizes (instrument size) so as to fix it inside our body to find the level of oxygen present inside the cells? 218.248.1.189 11:07, 16 January 2007 (UTC)

How much would it cost to build a hydrogen maser?

I was curious how much it would cost me to build a hydrogen maser, so that I could keep as accurate time as the US Naval Obseratory.

Thanks.

--69.138.61.168 13:50, 16 January 2007 (UTC)

Why settle for a hydrogen maser? Wouldn't you really prefer a cesium fountain clock? I mean, if you're going to go to all that trouble...

Atlant 17:37, 16 January 2007 (UTC)

I don't know how much it would cost, but it's much easier to synchronize your clock/watch with http://nist.time.gov. | AndonicO ^{Talk · Sign Here} 20:07, 17 January 2007 (UTC)

Realistically, many (most?) GPS receivers will give you time that's accurate enough for just about any practical purpose (easily "microsecondish" accuracy). Think of it as NIST's fancy clocks telemetered to your location.

Atlant 14:36, 18 January 2007 (UTC)

P wave of light

What is the wavelenth of a P wave of light? —The preceding unsigned comment was added by Clayton Sattler (talk • contribs) 14:44, 16 January 2007 (UTC).

Light has no set wavelength, and you can read about that at electromagnetic spectrum. Also, since light waves are not pressure waves they are not called P waves, but electromagnetic waves. P waves are called so in acoustics and seismology. X [Mac Davis] (DESK|How's my driving?) 16:25, 16 January 2007 (UTC)

Nikola Tesla believed that radio waves (and by implication light waves) were longitudinal waves, like sound. Physicists today disagree with him. Edison 06:14, 17 January 2007 (UTC)

chemistry

dear sir

i would like know the chemical synthesis of omeprazole drug.

regards

kr —The preceding unsigned comment was added by Svcr (talk • contribs) 14:58, 16 January 2007 (UTC).

The most recent patent covering its synthesis is: Turchetta, Stefano; Massardo, Pietro; Tuozzi, Angela. PCT Int. Appl. (2004), 15 pp. WO 2004056803 A1 This patent probably has plently of references to earlier methods as well. --Ed (Edgar181) 15:33, 16 January 2007 (UTC)

GENDER PREFERENCE IN ART

I'm looking for any articles or information on the difference between male preference in art vs female preference. For example, what colors do women prefer? What colors do men prefer? Do men prefer abstract art or impressionist? etc. I even looked for subjects on the female brain and male brain to see if they say what each gender prefers in terms colors, subject, etc. Thanks. —The preceding unsigned comment was added by Nhimdanh (talk • contribs) 16:41, 16 January 2007 (UTC).

That's a tough one, my guess is that gender preference is largely a societal construct, for example parents buying a pink baby blanket for a daughter and a blue one for their son, I don't think that has anything to do with preference. During the 80s a hetero male wouldn't be caught dead in a pink shirt, now they're all the rage.. Go figure. So, my answer to this would be that any study done on the subject would be extremely subject to national, cultural and even smaller demographical particularities and could out date quicker then the ink it is printed with would dry.. But that's just my opinion. As far as broader 'art trends' are concerned, as far as I know if hasn't often divided by gender, there hasn't typically been a woman's and man's following of different movements, good art is good art. I could be wrong;) Vespine 01:50, 17 January 2007 (UTC)

Benzyl cyanide

what is benzyl cyanide used for —The preceding unsigned comment was added by 207.195.79.101 (talk • contribs) 17:55, 16 January 2007 (UTC).

Benzyl cyanide is more usually called benzonitrile. The main use of benzonitrile appears to be as a powerful solvent in the pharmaceutical industry, and as an intermediate in the production of a triazine called "benzoguanamine", which is similar to melamine. Laïka 11:51, 17 January 2007 (UTC)

cold heat

Sometimes I feel like the side of my right hand is warm, or even hot, even though it shouldn't be. This feeling comes and goes randomly and seems to have only started a few months ago. Does anyone have any idea what might be causing this, and weather I should worry about it.Hidden secret 7 20:12, 16 January 2007 (UTC)

Please ask you doctor for medical advice. Friday (talk) 20:14, 16 January 2007 (UTC)

Remember we can talk about what it may be or if you should worry about it. Didn't we talk about this many times before on the talk page? We're here to give knowledge with a disclaimer, not censor it. X [Mac Davis] (DESK|How's my driving?) 20:33, 16 January 2007 (UTC)

No, I'm afraid we can't talk about it. Offering a suggested diagnosis ('This might be X') prognosis ('You should/shouldn't worry about this, because it's harmful/harmless problem X') or other medical guidance ('Take two aspirin, rub on some Windex, etc.) is beyond the scope of our mandate and qualifications. When our disclaimer says that we don't give medical advice, it means it.

Apologies to Hidden secret 7, but we're not able to answer your question. You should direct questions about your health to a qualified health practitioner: your doctor, a nurse, your local health clinic, your pharmacist, or (if you're a minor) your parents. TenOfAllTrades(talk) 20:42, 16 January 2007 (UTC)

I once had something like that after I got some capsaicin, from an extremely hot pepper, on my hand. It would be triggered by environmental factors. For example, if warm water hit my hand it felt like boiling water had been poured on it. This effect went away after a week or so. Is it possible that part of your hand was exposed to some chemical irritant when your symptoms started ? StuRat 06:00, 17 January 2007 (UTC)

Going to StuRat's observation (rather than the original question), you'll find that your skin contains three kinds of thermal sensors: Heat sensors, cold sensors, and "extreme" sensors (that detect relatively far-out values of either heat or cold). There's a wonderful demo of this at the Exploratorium: it has a series of narrow, alternating warm and cold copper pipes in very close proximity. The warm pipes are just warm, say 100F. The cold pipes are quite cold, say near freezing, and apparently cold enough to trip your "extreme" sensors. But if you lay your hands down so they're contacting both sets of pipes, you instantly get the sensation that your hands are being fried in boiling oil. Apparently, your brain says "heat sensors" + "extreme sensors" = "Holy $#!# !". It's very amusing. Perhaps the capsaicin caused your "extreme" sensors to be out of whack for a few days?

Atlant 14:45, 18 January 2007 (UTC)

Yes, something like that, although I was just thinking it caused a direct hypersensitivity in the "heat" sensors. StuRat 20:26, 20 January 2007 (UTC)

There's always the possibility that it's due to a damaged or under-pressure nerve, as happens in carpel tunnel syndrome. There's no need to play the symptom down or attribute it to something purely environmental. It could be anything, don't be shy about asking a doctor. -- Consumed Crustacean (talk) 16:30, 19 January 2007 (UTC)

ID a cat breed for me?

Can anyone tell me what type of cat this is? I know it's Siamese, but I'd like to know which type; they all look the same to me. I put Blue Point (?) on the description, but I'm not so sure. This comes under the heading of a Biology question, right? ^^ Rawling4851 20:33, 16 January 2007 (UTC)

Yes, that would be a blue point cat. Now unless you have papers certifying that it's a purebred cat, I wouldn't go as far as to say that it really is a Siamese. The colorpoint pattern can appear on any kind of cat. howcheng {chat} 20:35, 16 January 2007 (UTC)

OK, cheers. I'll ask into its heritage the next chance I get. Thanks for the reply :) Rawling4851 20:37, 16 January 2007 (UTC)

Howcheng is correct, but I'd put pretty good money on it being Siamese - the colour of the eyes, the size of the ears, the shape of the face all look Siamese. The only oddity is that the mouth isn't wide open and crying, which is apparently my Siamese's natural state. Perhaps it's a mix after all. Matt Deres 03:30, 17 January 2007 (UTC)

OK, that made me smile :) thanks for brightening my day. Rawling4851 22:16, 17 January 2007 (UTC)

BATTERIES

I am going to have to buy some new cycle lights very soon: A dealer has some re-chargeable twin-sets. one set has a NI-CAD Battery Pack the other has a LEAD ACID. In simple terms please, which would be better, and why. Emails to the dealer seem to have been ignored hence my question posted here. Thank you, Jonathan

Neither, they're very bad for the environment. NiMH batteries would be far better. TERdON 21:43, 16 January 2007 (UTC)

Lead-acid batteries are cheap and can provide very high current, which is why they're used as starter batteries for cars. They last longest if you never use more than about the top 25% of the battery's capacity, so you should recharge them every time you use them. They also provide very little energy per pound, which is why car batteries are so heavy.

NiCD batteries are more expensive and can't provide high current, which is not a problem for lights. They last longest if you recharge only when the batteries are fully drained. They provide about ten times as much energy per pound as lead-acid batteries.

If you can get them, NiMH batteries are like NiCD, only you can recharge them at any time, and they provide about three times as much energy per pound as NiCD.

Hope this helps. --Carnildo 21:33, 17 January 2007 (UTC)

On the other hand, the world understands very well how to recycle expired Lead-Acid batteries, and isn't nearly as good with NiCds or NiMHs. And the "self discharge" rate of NiCd and NiMH batteries is much higher than for Lead-Acid, so if you don't use your bicycle headlamp very often, you may often find the NiCd one dead (after just a few months) whereas the Lead-Acid one still has plenty of charge.

As with everything, there are trade-offs.

Atlant 14:49, 18 January 2007 (UTC)

Health question

I've already asked this question but when i came back to check for the answer, my question had disapeered. its not old enough to be archived so im suspecting foul play here. Anyway, can any1 tell me what happens if i eat a square foot of saran wrap??

This question asks for medical advice. The Reference Desk cannot offer competent professional advice on questions of this kind. If you have concerns about a potentially serious medical problem, please immediately contact a qualified healthcare professional.

I cannot find any references for someone having eaten a sheet of the material, so the answer is likely to be that no-one knows what the mechanical effect would be. The MSDS on the PVDC is quite remarkable, it seems to have no toxicity, BUT that does not include the plasticisers. If you can find out what they are, then you can search for an MSDS on them, and make your own conclusions. --Seejyb 00:02, 17 January 2007 (UTC)

Google is remarkably quiet on the issue, but if you want to find out what would happen when a Labrador Retriever swallows cling wrap, READ ON. Anchoress 00:09, 17 January 2007 (UTC)

My grandfather (who died over 50 years ago) believed that if one ate tomato skins he would get "all dobbed up." A muckraking book by Consumer Reports, "100 Million Guinea Pigs (1932)" expressed similar doubts about the usefulness of indigestible fiber in the human diet. Edison 06:20, 17 January 2007 (UTC)

That's interesting, I don't see anything like that in the article. X [Mac Davis] (DESK|How's my driving?) 14:00, 17 January 2007 (UTC)

I don't know for you, but for the labrador it might be very useful when you take it for a walk in the street. -- DLL ^{.. T} 19:16, 17 January 2007 (UTC)

appropriate/inappropriate medical image guidelines

I'm going to contribute an Integumentary System image diagram for the Integumentary System article. This image was created from a CT scan of a healthy man and woman and then male and female texture maps were applied to the 3d models (the image is a render of a 3d model we built). Do I need to 'fuzz' out the private parts or is it okay to show it all since it is purely scientific? 3dscience 22:46, 16 January 2007 (UTC)

Wikipedia is not censored so you should be fine. Rawling4851 22:20, 16 January 2007 (UTC)

Considering that we already have close-up actual photographs of Penises, Vaginas and Anuses at WP, I doubt that any sane person will complain. --Kurt Shaped Box 23:40, 16 January 2007 (UTC)

Correct. No normal person will complain. --Light current 00:31, 17 January 2007 (UTC)

Have you checked out our lovely 'taint', as a matter of interest? :) --Kurt Shaped Box 00:38, 17 January 2007 (UTC)

Sounds like a term from the HBO series Deadwood. Something Al Swearengen would sell for a buck at The Gem Saloon. Probably not the subject of the Wiki article. Edison 06:26, 17 January 2007 (UTC)

Chemistry Resources

I am currently studying Triple Science for GCSE and find Chemistry particularly interesting. Unfortunately, in my teacher's and mine opinions, the GCSE course is rubbish. It doesn't give any reasons or explanations for anything, just lists facts. My teacher does everything that he can to give us extra information that the examination board has decided that we don't need to know. Unfortunately, he just doesn't have the time to tell us all the 'interesting' and 'useful' things about Chemistry that the GCSE course just misses out. As such, can someone recommend some good online resources for learning about chemistry, from information about atomic structures such as electron orbitals to Van der Waal forces? I have had a look on Wikibooks but the articles on there seem to be half finished and don't explain things particularly well considering that they are aimed at the beginner. Although the Wikipedia articles contain a great deal of information, they are not the best resource to learn from as they are not arranged in any particular order, and looking up the Wikipedia article on a topic that you have never heard of before in order to learn about it quite difficult. Obviously, being a GCSE student (that's 14-15 years old for all you non-English people) I would prefer the explanations to be given in a style that doesn't require a degree in some obscure field to understand. However, I do not mind if the text is slightly complicated and am willing to read material multiple times before understanding it. Thank you for any suggestions you may have. --80.229.152.246 21:55, 16 January 2007 (UTC)

You could try BBC Bitesize GCSE Chemistry pages. No personal experience, but I've heard good reports from GCSE pupils who have used them. They also have a list of other chemistry web sites here. Gandalf61 22:03, 16 January 2007 (UTC)

I seem to remember that [LearnChem.net] was reasonably good. But you can always just get a chemistry textbook, which would cover the things you are talking about. BenC7 02:26, 17 January 2007 (UTC)

I don't want GCSE-based sites though because the course is rubbish and I want to learn more than that. A chemistry textbook would be a good idea, but I would like to see if there are any online resources first. Thanks for your help. --80.229.152.246 16:26, 17 January 2007 (UTC)

Try http://www.creative-chemistry.org.uk/ it goes up to A level and is really fun. The BBC is excellent as well. Although I have to say the words "beyond the scope of this article" exist at all levels up to and including degree level. Theresa Knott | Taste the Korn 15:57, 18 January 2007 (UTC)

Fusion Rocket

I have been researching spacecraft propulsion and I found the fusion rocket which reminds me of the Space Odyssey Series. My question is why can't we build one of these rockets in Space and launch it there, then we wouldn't have to worry about radiation?67.126.129.85 22:51, 16 January 2007 (UTC)

It depends on what type of rocket you are talking about — are you referring to Project Orion? If so, there are a number of practical difficulties in using a rocket fired by fusion bombs. If you really meant a fission rocket, such as a nuclear thermal rocket, there are no real practical reasons that I know of of why one couldn't be made if it was desirable, aside from the fact that it would still be quite slow in navigating the vast distances between interstellar objects (which in the end is the largest limiting factor behind all space travel ideas). Additionally I think it is currently quite beyond the capabilities of any space program to build an entire rocket in space; one could imagine assembling components and maybe having that work, but it would still be pretty difficult from a practical point of view. And you'd still have to get all of the radioactive components up into space, as well, provoking the same sorts of political controversy that you'd probably have from just launching one (if the rocket going up blew up, you'd spread radioactive debris over a very large area). --24.147.86.187 23:07, 16 January 2007 (UTC)

Perhaps the nuclear materials could be mined off-Earth, such as on the Moon or asteroids ? StuRat 02:46, 17 January 2007 (UTC)

They'd have to be processed heavily before being usable (milled, refined, etc.). Which doesn't mean it is impossible but now we're making even larger assumptions about the level of practical technology way beyond what is currently done. (We've never even establish a factory of any size anywhere other than earth, much less one which handles the nasty corrosive chemicals required for uranium milling). --24.147.86.187 15:20, 17 January 2007 (UTC)

Size of fusion gas tank...?

...and what size fusion gas tank would you need to travel a gazillion miles? 71.100.10.48 23:39, 16 January 2007 (UTC)

Assuming you are using a standard engine running at approximately 73.4 dooviewhackies per parsec, you'd need about six 90 kilofarnsworth tanks of juice. Vespine 01:15, 17 January 2007 (UTC)

...how about with a Cadiddle Hopper 49701? -- 71.100.10.48 02:38, 17 January 2007 (UTC)

Maybve you refer to a Red Skelton "Kadiddlehopper ." Edison 06:33, 17 January 2007 (UTC)

You only need to expend enough fuel to reach escape velocity for whatever orbit that the rocket is in. After that point, it (more or less) will just be carried by it's own momentum through space. There will be a slight source of friction from radiation pressure or particles in the 'vacuum', but for the most part, the rocket will travel on for a long long ways.

Well another important part of my question is wether or not if a fusion explosion could be controlled with magnets with current technology?67.126.129.85 06:14, 17 January 2007 (UTC)

Future technology? Sure. Present technology? Problems, maybe. Remember that neutron are not ions, so their flow is not subject to action by magnetic fields. Edison 06:33, 17 January 2007 (UTC)

Thank You for all your answers.

Gallium corrosion

Does Gallium react with or corrode copper?

It dissolves the surface and forms amalgam. I don't know if it causes Liquid_metal_embrittlement though.--Wjbeaty 02:23, 17 January 2007 (UTC)

Battery load testing..?

What is the formula for determining the results of a 40 ohm load placed across the terminals of a 12 volts battery using the time it takes for the voltage to drop from btween 13.4 volts and 12.8 volts to 10.5 volts and what are these results called? 71.100.10.48 23:34, 16 January 2007 (UTC)

Perhaps you are referring to a Lead-acid battery , which has about 2 volts per cell. The discharge curve as you describe would depend on the ampacity of the cells in the battery. Larger cells would have less of a drop of voltage for a given ampereage. Edison 06:37, 17 January 2007 (UTC)