Wikipedia:Reference desk/Archives/Science/2007 September 18

= September 18 =

soil conservation
how does science and technology benefit soil conservation


 * Science and technology are very important to soil conservation. Without science and technology, soil conservation would be much more difficult.  Many scientists and technologists around the world are working very hard to contribute to soil conservation, including Illinois.  In conclusion, I think science and technology benefit soil conservation in many important ways.  The end.  &mdash;Tamfang 00:52, 18 September 2007 (UTC)


 * Well it all starts with doing your own homework...  Plasticup  T / C  00:53, 18 September 2007 (UTC)


 * --Shantavira|feed me 07:31, 18 September 2007 (UTC)

Fuzzy Logic
Is Fuzzy Logic science or mathematics? 202.168.50.40 03:11, 18 September 2007 (UTC)
 * Math(s). —Tamfang 03:29, 18 September 2007 (UTC)
 * I'm not sure I'd call it either science or math. It seems to be used solely by industry; I can't recall a pure mathematician ever expressing interest in it. The mathematician's version of fuzzy logic is Bayesian inference, which has different rules. -- BenRG 10:01, 18 September 2007 (UTC)

Isn't Defuzzification the same as Collapsing the Probability Wave in Quantum Mechanics? What about the similarity between Fuzzy Logic and Quantum Wave Theory. Both seems to deal with "All possible worlds" before collapsing into one observed result. 202.168.50.40 05:24, 18 September 2007 (UTC)
 * Not really - fuzzy logic is just probability based decision making under another name, wave function collapse is something else that can be related to probability.87.102.7.192 09:41, 18 September 2007 (UTC)
 * The collapse of the wave function does look like a Bayesian update. This was noticed by the founders of quantum mechanics, and led to a lot of rather embarrassing speculation about consciousness and mind-over-matter (because the Bayesian update is about subjective knowledge, but the wave function collapse is a physical effect). Eighty years later, the connection between quantum statistics and Bayesian inference seems to still be unclear, like everything else about the foundations of QM. But I can say with some confidence that fuzzy logic has nothing to do with QM. -- BenRG 10:01, 18 September 2007 (UTC)
 * It's applied mathematics. It's a branch most often used in practical technology (mostly computer software) rather than in pure mathematics. SteveBaker 13:16, 18 September 2007 (UTC)

Adjusting to high altitude
I understand that if you go up to 6,000 or 7,000 ft above sea level you can dehydrate and get headaches, and that it can require as much as 6 weeks for your body to adjust. My question: what exactly is the body's adjustment? Do we create more hæmoglobin? Thanks. PaulTanenbaum 04:12, 18 September 2007 (UTC)
 * Yes (more red blood cells). --> Altitude training.  Someguy1221 04:41, 18 September 2007 (UTC)
 * After many years at altitude, you create too many. --> Polycythemia. --Mdwyer 14:40, 18 September 2007 (UTC)
 * I don't quite understand. Why is it "too many"? The article doesnt seem to discuss any disadvantages. Yet is calls people with the condition "sufferers". Is the article of poor quality? Capuchin 14:47, 18 September 2007 (UTC)
 * Polycythemia vera lists many nasty reasons you wouldn't want that particular brand of it. Someguy1221 16:08, 18 September 2007 (UTC)

Suspension of Disbelief
This is a question of psychology. As I am not a psychiatrist or a psychologist, please keep your answers on the simple, non-technical side. Thanks. I don't quite understand this. Can someone please explain? When I watch a film or a TV show, my brain knows and understands that the whole thing is "fake" and not truly happening in real life. A physical example: when I see a character get stabbed ... my intellectual side knows that it is just an actor, reading from a script, with a fake knife and fake blood as props. That is, a real person did not just suffer a real stab wound from a real murderer with a real knife and is now bleeding real blood. An emotional example: when I see a husband/wife argue and fight and get a divorce on a soap opera ... my intellectual side knows that it is just a group of actors, reading from a script, with no real fight or real divorce involved. So, this is my question. If the intellectual / intelligent part of my brain knows and realizes and accepts this, how exactly is it that a film or TV show can get me scared or nervous or happy or sad or whatever? In other words, why do people get scared / nervous / frightened / upset when they see the shark attacking in Jaws and they "know" that the whole scene is a fake / a sham? What is happening with the brain that allows us to experience "fear" in such an irrational manner? (Irrational = "I know that this is all fake and not really scary, yet I am still scared.") Why do people get happy / sad etc. when fake characters on a soap opera engage in a fake wedding or a fake divorce or a fake fight or a fake death or whatever? (fake=fictitious) How is it that the rational / thinking side of our brain / intellect gets "fooled", if you will, by the film or TV show or acting or writing, etc.? Thanks. (Joseph A. Spadaro 05:00, 18 September 2007 (UTC))
 * Well, I found a paper on it. Here.  Someguy1221 05:12, 18 September 2007 (UTC)
 * I think empathy has a lot to do with it. We are able, and all too willing, to put ourselves in the shoes of the protagonists and "experience" what he or she is going through emotionally. Rockpock  e  t  06:16, 18 September 2007 (UTC)
 * Our brain hasn't evolved to deal with actors. Capuchin 11:42, 18 September 2007 (UTC)
 * As with most systems of any complexity, the brain has layers of interpretation from the lowest level perception of colours, shapes, motion, sounds, etc - though the level that recognises people, sharks, water - then into the level that produces 'gut reactions' of surprise, fear, etc - then the higher levels of 'what to do about this'. It's likely that only the highest levels of processing are able to assemble enough context together to realise that this is all fake - the lower levels of processing having already acted on the basis of the information being real. SteveBaker 13:13, 18 September 2007 (UTC)
 * I am not sure how much empathy comes into play, I have a marked lack of empathy and I don't think I enjoy movies any less than the next person. Although I admit I do prefer action to romance, but that may be more to do with my gender. If you can identify with the situation the actors are in it may illicit more of an emotional response perhaps. Lanfear&#39;s Bane 15:42, 18 September 2007 (UTC)
 * Our article on empathy is a little, ahem, uneven to put it politely, but there are several definitions of empathy. The common one I knew about growing up was, as you suggest, being sympathetic (compassionate) about someone's situation. A wider definition is more about identifying with the other person, putting yourself "in their place", which might be more like what Rockpocket was talking about. You become scared or sad not because you feel sorry for the characters, but because you see yourself in their predicament. Also see Emotional contagion, though the article needs a lot of fact-checking and referencing, etc. Matt Deres 16:28, 18 September 2007 (UTC)

Methanol poisoning
If ethanol treats methanol poisoning, why is alcoholic beverages that contain a small amount of methanol dangerous? Jack Daw 14:20, 18 September 2007 (UTC)
 * Ethanol DOES NOT treat methanol poisoning.87.102.7.192 14:25, 18 September 2007 (UTC) The article on methanol states that ethanol may be used in cases of methanol poisoning to compete with the methanol for the 'enzyme' that breaks down methanol into harmful components.. This assumes that the breakdown products of ethanol are less harmful than those from methanol. This doesn't stop methanol and ethanol from being poisonous it's just than ethanol is less worse.87.102.7.192 14:29, 18 September 2007 (UTC)
 * Considering that ethanol is a widely socially accepted form of intoxication and not comparably a poison at all, which methanol is, we can quite safely assume "that the breakdown products of ethanol are less harmful than those from methanol". Jack Daw 15:32, 18 September 2007 (UTC)
 * A lot depends on the concentrations required to achieve the effect. Ethanol is most definitely toxic in sufficient quantities - we normally drink the stuff heavily diluted with water. SteveBaker 16:46, 18 September 2007 (UTC)
 * acetaldehyde and acetic acid are far less toxic than formaldehyde and formic acid, because they are more reactive.--134.76.234.75 17:28, 18 September 2007 (UTC)

So what's the answer to this question, are alcoholic beverages containing small amounts of methanol dangerous or not? —Preceding unsigned comment added by 12.217.199.246 (talk) 23:06, 18 September 2007 (UTC)
 * Yes. In fact all alcoholic beverages are dangerous. In fact everything is dangerous.
 * Just how dangerous depends, among other things, on how small is small. Poorly made moonshine can definitely contain enough methanol to be a problem. The mere fact that it also contains ethanol is not something you can rely on to protect you, because the ethanol may not monopolize the alcohol dehydrogenase for long enough for your kidneys to remove the methanol from your blood. --Trovatore 02:51, 19 September 2007 (UTC)

Breast size
How many years after first period do the breasts stop growing? --124.254.77.148 14:41, 18 September 2007 (UTC)
 * They never stop.87.102.7.192 15:06, 18 September 2007 (UTC)


 * It's going to depend on the individual, of course. We have an encyclopedia article on puberty that may prove useful.  Friday (talk) 17:04, 18 September 2007 (UTC)


 * Both of the above answers are considering different issues. The female breast will mostly stop increasing in size some time after puberty. However as with all living body parts, it does not stop growing until you die. There is constant cellular regeneration as well as some specific changes during pregnancy. Even the size fluctuates somewhat outside of pregnancy. Breast covers this in some detail Nil Einne 21:16, 18 September 2007 (UTC)
 * erm breasts do get bigger with age (after puberty whatever that is) - that is I haven't yet seen teenage girls with 54DD breasts yet is not uncommon in women of a mature age..87.102.116.240 17:12, 19 September 2007 (UTC)
 * Read my response carefully. I said sometime after puberty. The precise time varies but it would AFAIK usually be in the late teens of perhaps early adulthood. (This ref suggests you will usually know the final size by 17-18 although obviously there will be some who continue past then) An actually I'm pretty sure natural 54DD breasts are quite uncommon in women of a mature age (although more common then in teenage girls obviously) Nil Einne 20:20, 19 September 2007 (UTC)
 * Also, remember that breast size fluctuates with weight - if you lose a lot of weight your breasts often shrink in proportion, and similarly, if you gain weight, you gain breast size, as more fat is stored in them. My grandmother has giant ones - but she's a very large woman (and apparently had thyroid cancer, so that could be a cause). Mine fluctuate from a 36D to a 34C when I go from around 170lbs to 150 or so. It's all in how much fat is behind them, sort of pushing them out. Kuronue | Talk 23:38, 21 September 2007 (UTC)

Daisies and temperature
Can real daisies alter a planet's surface temperature the way they can in DaisyWorld? If so, could we theoretically reduce global warming by seeding large areas with white daisies, or delay the early stages of the next ice age using black daisies? Neon Merlin  15:57, 18 September 2007 (UTC)


 * I suppose so - the effect of the polar ice (white, shiney!) melting and being replaced by seawater (dark) is measurable in terms of increasing the effect of planetary warming...so I guess if you could plant enough daisies, it would have an impact too. It's obviously not a particularly practical scheme though - the areas covered would have to be enormous - and the consequential impact on biodiversity would undoubtedly be serious. SteveBaker 16:44, 18 September 2007 (UTC)


 * I dunno, but it's similar to a Snowball Earth. I wonder, though, how reflective white daisies are to IR.  --Reuben 19:46, 18 September 2007 (UTC)
 * Yeah - it's hard to say. I'd hazard a guess that they were more reflective than green plants though - leaves are designed to absorb sunlight - petals aren't.  SteveBaker 20:54, 18 September 2007 (UTC)


 * If they are like in Daisyworld, planting daisies won't change the temperature. The numbers of each shade of daisy will move towards equilibrium. — Daniel 22:43, 18 September 2007 (UTC)
 * That's just because it's a contrived example though. They set it up so that black daisies grow better in cool temperatures and white ones prefer the warm.  As the temperature rises, the number of white daisies goes up and the number of black reduce - this causes the white ones to reflect more heat away resulting in the temperature dropping.  No matter which way the temperature swings, the daisy growth rates will adjust and pull the temperature back to something they can both tolerate.  This doesn't really mimic anything in the real world because the black daisies might very well evolve to be more heat-tolerant in order to out-perform the white daisies on warm days, which would allow the temperature of the planet could spiral upwards in an uncontrolled manner.  Still, as a teaching tool, it's not bad. SteveBaker 14:33, 19 September 2007 (UTC)
 * It's not entirely contrived. After all, the black daisies themselves absorb more heat from sunlight than the white ones.  So if both types had the same limits on their absolute heat tolerance (perhaps due to hard physical limits), the white daisies would be expected to do somewhat better at high temperatures and vice versa.  Of course, it's still an extremely simplistic model.  —Ilmari Karonen (talk) 20:25, 19 September 2007 (UTC)

Treating methanol poisoning with IV vodka/whiskey?
Does this actually work in the real world? I've seen this used as a plot device in shows like Casualty and Holby City on several occasions. --Kurt Shaped Box 17:46, 18 September 2007 (UTC)


 * I cannot imagine any reputable medical facility would use something intravenously that wasn't meant for this route of administration. Surely medical grade ethanol would be preferable?  Friday (talk) 17:51, 18 September 2007 (UTC)


 * In the storyline, it's usually the case that they've run out of ethanol - so they have to raid the drinks cabinet/go down the off-licence. Makes more interesting TV, I guess. There was a scene in House M.D. where Dr. House downs a bottle of whiskey with a methanol victim in order to flush the toxins from his system - instead of say, just hooking a bag to the guy's drip... --Kurt Shaped Box 17:54, 18 September 2007 (UTC)
 * Well, it'd be sterile... -- Flyguy649 talk contribs 17:58, 18 September 2007 (UTC)
 * Not saying that this is a healthy thing to be doing (or even a good idea - so don't try it, kids) but I used to know of someone whose party trick was to shoot whiskey into his veins. It didn't kill him - well he was still alive a couple of years ago, at least. He was a roadie for my friend's band - it was all very rock 'n' roll... --Kurt Shaped Box 18:30, 18 September 2007 (UTC)
 * To answer the question: it's possible, but I'm not sure.  I know ethanol is used to treat isopropyl alcohol poisoning, so it's quite possible that it would be used for methanol poisoning.  The reasoning behind ethanol's use in isopropyl is that ethanol is competitive to alcohol dehydrogenase.  Alcohols, by themselves, aren't nearly as toxic as what they're broken down into (i.e. aldehydes), so the reasoning behind using ethanol in cases of isopropyl poisoning is to simply keep alcohol dehydrogenase busy while isopropyl is being naturally excreted by the kidneys (since it's a small enough chemical and since ethanol is also a diuretic).  So, while the person will get ridiculously drunk, he'll live.  Also, as far as I know, that's the only prescribed treatment if I remember correctly.  So, it would make sense that the same approach would be used in cases of methanol poisoning, but again, I'm not certain.  As to the IV route, I haven't heard of it being used. From what I've seen in the ethanol-countering-isopropyl route, it's just given PO (by mouth), since alcohol is irritating to connective tissue and it's readily absorbed from the gastrointestinal tract.  -- slakr  \ talk / 18:44, 18 September 2007 (UTC)
 * ... which also reminds me. Everything from the GI tract gets first-pass at the liver, so it's a more direct route than IV/IM anyway. -- slakr  \ talk / 18:49, 18 September 2007 (UTC)


 * I think you're thinking of ethylene glycol, not isopropanol. Isopropanol is not really all that poisonous I think; mostly it makes you sick (alcohol dehydrogenase turns it into acetone, which is not all that bad). That makes it a somewhat less vicious way of protecting the government's revenues than denaturing with methanol.
 * By contrast ethylene glycol turns into oxalic acid, which destroys your kidneys, and methanol turns into formic acid, which makes you go blind. As you say, a little bit of alcohol (a "beer" as an earlier poster put it) will not protect you from this. You need to tie up all the alcohol dehydrogenase until all the ethylene glycol or methanol is removed by the kidneys, which could take some time. I think there's now a less damaging pharmaceutical for doing this, without the brain damage involved in staying hammered for a day or so. --Trovatore 19:10, 18 September 2007 (UTC)
 * Fomepizole is what you are referring to, but in veterinary medicine it's still fairly common to use ethanol (usually vodka) IV for ethylene glycol poisoning. This is due to the cost of fomepizole and the fact that not everyone keeps it on hand.  Interestingly, ethanol, not fomepizole, is the treatment of choice in cats.  --Joelmills 19:40, 18 September 2007 (UTC)
 * Acetone is toxic through ketoacidosis, a condition one wants to avoid. Beer is of far too little of a concentration of ethanol, so whisky (or another high-proof spirit) is used instead.  Saturation of alcohol dehydrogenase occurs rather easily with oral absorption of ethanol, as referenced by the linear breakdown curve that countless law enforcement agencies and learn-to-drive schools love to parade around. -- slakr  \ talk / 19:22, 18 September 2007 (UTC)


 * I'm not claiming that isopropanol, or acetone, is exactly good for you. The isopropanol article says While large quantities of isopropanol can be fatal if left untreated, it is not nearly as toxic as methanol or ethylene glycol. The acetone article says Relatively speaking, acetone is not a very toxic compound; it can, however, damage the mucosa of the mouth and can irritate and damage skin. Accidental intake of large amounts of acetone may lead to unconsciousness and death. So I still sort of doubt that you're thinking of ethanol being used to treat isopropanol poisoning. It's much more likely that you're thinking of ethylene glycol, or methanol. --Trovatore 02:19, 19 September 2007 (UTC)

Batteries
Hi all,

If I hook a battery up to an LED, with the appropriate resistor in series, and leave it on, the battery will eventually run out. If I hook up a bigger battery (more volts, say, a 12 Volt battery), and change the resistor so that the correct amount of current is flowing, will the battery last longer? Or will the increase in resistance mean that the battery will be doing more work so there would be no difference?

Thanks! --Mary 18:05, 18 September 2007 (UTC)
 * See Ohm's law and Power (physics). -- slakr \ talk / 19:02, 18 September 2007 (UTC)


 * Perhaps more accurately, you'll want to check the amp-hour rating (generally expressed in milliamp hours, or mAh) to estimate battery duration. Voltage really has nothing to do with this, as not all 1.5V batteries are created equal -- do a quick comparison of an AAAA battery with a D-cell. Anyway, to estimate your battery use, divide the battery's mAh rating by the current pulled by your circuit.  Note that stacking batteries in series does not mean that you add their mAh ratings together. &mdash; Lomn 20:07, 18 September 2007 (UTC)  —Preceding unsigned comment added by Lomn (talk • contribs)


 * Take a look at Battery (electricity) for some averages. Note that although it'll be useful to predict how long your battery will last with a given load (the LED case), it doesn't directly tell you how much energy the battery stores (as explained in the linked page). For example a latern battery which usually AFAIK has 4 F type cells has a mAh of an F type cell. However it's delivering 4x the voltage so has a store of 4x the energy. Assuming you have a perfect voltage regulator (obviously such a thing can't exist) you could power a device for 4 times the length you could with a single F type cell. When you're simply using a current limiting resistor obviously the mAh is all that really matters Nil Einne 21:00, 18 September 2007 (UTC)

Iris Color Change
Are there any reported cases in which a person's iris color had changed from say, dark brown to blue or green, without any diseases involved? --WonderFran 19:30, 18 September 2007 (UTC)


 * Yep&mdash;this came up at the Ref Desk a few months ago (link to archive). There's some good information in Eye color and Iris (anatomy). TenOfAllTrades(talk) 20:26, 18 September 2007 (UTC)

Want to buy a new parrot/parakeet - suggestions?
I already have a Sun Conure, which is a lovely bird. But she can be a handful at times and very strong willed and independent. I want to get another parrot (to keep alongside her) but I want one that's a lot quieter, tolerates being held and stroked more and doesn't bite without warning as much. Anyone know of any species like this? Thanks. --90.240.248.51 20:57, 18 September 2007 (UTC)
 * Don't forget to investigate whether your two pets will get along well. It sounds like there is a risk the Sun Conure might attack any new pet. Also, while I've never kept birds as pets, I would presume that as with most pets their temperaments can be quite variable. Although certain breeds may be much more docile, there is no guarantee the temperament will be what you want. You might want to consider adopting an adult from someone who has kept the bird for a while and say knows the temperament Nil Einne 21:11, 18 September 2007 (UTC)
 * Yep, temperament varies from parrot to parrot - though in my experience, most of them are prone to fits of pique (i.e. sudden biting) if you unwittingly annoy/scare them. The fight/flight response is never too far below the surface in these birds. I've heard that Bourke's Parrots and Lineolated Parakeets are generally pretty calm and quiet as far as psittacines go - but it's all relative. Don't get a Lovebird - it's a complete misnomer. As scrappers and biters go, they're right up there (don't let the cuteness fool you). Separate cages for the Conure and your new bird are a must - at least at the beginning. --Kurt Shaped Box 21:29, 18 September 2007 (UTC)

Color of beta-Carotene
I noticed that beta-carotene is used to color margarine and vanilla ice cream - which are yellow, not orange like carrots which are said to get their color from beta-carotene. Does anyone the real color of beta-carotene? Icek 22:31, 18 September 2007 (UTC)
 * you can use this to find the exact color of beta-carotene
 * http://www.ch.ic.ac.uk/wiki/images/0/0d/SpectraCarotene.jpg —Preceding unsigned comment added by 12.217.199.246 (talk) 23:10, 18 September 2007 (UTC)


 * Carotene, like many other complex pigments, has different colors at different concentrations. "Carotene is a common ingredient used in commercial colored oleomargarine to impart a yellow color. A typical useage level is five (5) milligrams beta-carotene per pound of oleomargarine, or 0.0011%. At this level, the color is light yellow. At 0.011% the color is still yellow. At 0.11%, the color is orange-brown and at 1.1%, the color is reddish-brown." —Keenan Pepper 02:58, 19 September 2007 (UTC)


 * An interesting side note is that for many years it was illegal in most places to color margarine yellow (thanks to dairy industry lobbying), and in some places they even forced producers to dye it some unappetizing color. --Sean 16:27, 19 September 2007 (UTC)
 * The things one can learn around here! "Bootleg colored margarine became common, and manufacturers began to supply food-coloring capsules so that the consumer could knead the yellow color into margarine before serving it." margarine. DMacks 00:33, 20 September 2007 (UTC)
 * Hang on, vanila ice cream is white...not yellow
 * Depends what type you buy, here in the UK it's invariably yellow. Capuchin 10:59, 21 September 2007 (UTC)