Wikipedia:Reference desk/Archives/Science/2007 June 30

= June 30 =

Black spots in front of eyes after vigorous coughing?
I got some food stuck in the wrong pipe this evening and was coughing and spluttering hard for several minutes. After I managed to dislodge the morsel, I sat around to catching my breath and clearing my throat. It was then that I noticed (whilst staring at a white wall) many tiny black spots swimming around and blinking in and out of existence in front of my eyes. What was that all about? Does WP have an article on this phenomenon? --Kurt Shaped Box 00:42, 30 June 2007 (UTC)


 * You were 'seeing stars'. So no article under that title--Tugjob 00:49, 30 June 2007 (UTC)


 * The article is called phosphene. Seeing stars should redirect there, and now does. --mglg(talk) 01:22, 30 June 2007 (UTC)


 * Some people notice that phenomenon in the presnece of low blood sugar or low blood pressure. Don't know how that relates to coughing. Edison 05:20, 30 June 2007 (UTC)

manufactured prescription drugs
I am trying to find out in what year was the first manufactured prescription drug made and wha was it, like the name of it and who manufactured it and what was it for?

I am a certified pharmacy technician and I think this would make a great trivia question to discuss with my pharmacist.


 * Medical prescription claims that prescriptions have been around since "the beginning of history." This section could use some copy editing! Nimur 01:39, 30 June 2007 (UTC)


 * See also Galenic formulation, named for Galen; Hippocrates, even earlier... and of course, Timeline of medicine and medical technology. Nimur 01:42, 30 June 2007 (UTC)


 * This is actually a reliable source, being an accredited, degree-granting institution with a college of Pharmacy... but I can't help but wonder if they are seriously suggesting that cavemen were pharmacists... Nimur 01:49, 30 June 2007 (UTC)


 * Pharmacists and doctors in the 19th century had little machines to compress medicine into pills. Does this amount to manufacturing? In the 19th century, companies put "patent" medicines, which might contain alcohol and opiates, into bottles with labels expounding all the things the medicine "cured." Was that manufacturing? Edison 05:19, 30 June 2007 (UTC)

Job
I have a job that involves me being on my feet nearly the entire time and crouching down. Is there any way I can avoid hurting my feet or back while at work?71.218.35.192 03:22, 30 June 2007 (UTC)


 * Softer shoes perhaps? --JDitto 04:14, 30 June 2007 (UTC)

well, i have to wear dress shoes71.218.35.192 04:32, 30 June 2007 (UTC)


 * If you have to stay standing for long periods, its best to try to lean forward a little while you are standing so your weight is more on the balls of your feet than the heel. It really works, especially if you're in smart shoes. Tree Kittens 06:16, 30 June 2007 (UTC)


 * As for back pain, I find back exercises such as pull-ups (or if that's too easy for you, pull-ups with weight) to cure it really fast. Of course, I'm not a physician and I can't see your particular case, I just dropped it here because it may be useful for someone. --Taraborn 07:06, 30 June 2007 (UTC)


 * You may need to see a doctor and get orthotics fitted and made for you. My niece had to do this - they're not cheap (over AU$300 plus the doctors fees), but she says they do work and can be worn with most shoes, other than open shoes. --jjron 13:39, 30 June 2007 (UTC)


 * I had a job that involved me standing and walking all day (it was in the back room of a store). I found that bringing an extra pair of tennis shoes helped a lot — when I was out of sight of customers, I would slip into them. --24.147.86.187 14:47, 30 June 2007 (UTC)


 * If your problem is caused by standing all day, you will just get used to it. It took about a week for me until my feet didn't hurt any more when I worked at a hospital.


 * That's a rather small sample size. If 71.218 is wearing shoes that do not properly support his weight, he may never "get used to it" and the pain may just get worse day by day and he may eventually do severe damage to his feet and spine.  --  JackofOz 01:58, 1 July 2007 (UTC)


 * The problem with custom orthotics (besides the price) is, use of support devices in your shoes causes the muscles in the foot to weaken and atrophy, which causes more pain, which requiring more cushioning and more support. It's a bad cycle to get into. The best solution is a strong, thick, spongy gel or foam (or both) sole pad to a naturally supportive pair of shoes. This will make walking on hard floors much less stressful, and will actually strengthen the musculature of the foot. Also, there are specialty shoe models specifically for workers with constant-standing jobs. I can't remember the manufacturers (try New Balance and Dexter), but I have seen casual and dress models in various catalogs. 97.82.247.200 15:56, 1 July 2007 (UTC)


 * You may want to consider a back brace, as well. Corvus cornix 19:04, 1 July 2007 (UTC)
 * Sports physicians recommend that if you are standing a long time, raise one foot by putting it on a small stepstool or such. My doc used to open the bottom file drawer and put one foot on that. Keeps your back at the proper curvature. Gzuckier 16:05, 2 July 2007 (UTC)

If a Tree Falls in the Forest ...
Perhaps this is a naive question, but ... how has science resolved the dilemma presented in "If a tree falls in the forest, and no one is there to hear it, does it make a sound?" ...? Thanks. (JosephASpadaro 04:33, 30 June 2007 (UTC))


 * See If a tree falls in a forest. 152.16.188.111 04:46, 30 June 2007 (UTC)


 * Ignoring the human-centric philosophical mumbo-jumbo in the article that underlies and 'explains' this 'dilemma', if you want a simple answer, think about the physics. A falling tree needs to convert a lot of gravitational potential energy into other forms of energy. As it falls this will be largely (but not entirely) kinetic energy, when it hits the ground, this will then be converted again, mainly to heat and sound energy. So there's the answer, of course it makes a sound, physics couldn't give a damn whether or not there's a human there to hear it. Oh, BTW, I always liked Bart Simpson's solution to that other dilemma, what is the sound of one hand clapping. --jjron 13:08, 30 June 2007 (UTC)


 * Strictly scientifically, sound is the vibration of matter. When a tree falls, it most certainly creates vibrations in the ground, in the air, and as a propagating sound wave.  The question at hand is a philosophical inquiry against the rigid definition of sound by bringing in the element of "human perception."  Science neatly sidesteps this issue with a careful definition.  Without doubt, sound is produced.  Nimur 17:06, 30 June 2007 (UTC)

It's very simple: if by "sound" you mean "sonic vibrations trough air or another medium", then yes, clearly sound is produced. If you mean "perception of sonic vibrations by a human being", then equally clearly, there is no sound. If you're not sure what you mean, you can debate this forever. There's probably a lot of similarity to the debate over whether animals feel pain. —Steve Summit (talk) 17:19, 30 June 2007 (UTC)


 * We don't ever use your second definition of the word "sound" - it cannot be found that way in any dictionary. Why create new, bizarre definitions of words in order to try to justify the pathetic attempts of philosophers to sow doubt and confusion where there is none?


 * We can leave a computer deep in the woods - recording the 'vibrations in the air' using a microphone. After it is determined that a sufficient amount of time has elapsed for numerous trees to have fallen we may retrieve the computer and have an expert who has been deaf their entire life examine a graphical display of the recorded vibrations from the microphone to determine what happened.  From this it is easily determined whether there was sound or not without any human perception of those acoustic vibrations.  We could go further by recording the sound of numerous tree-falling-events with a human test subject present - and program our computer to calculate whether there was a similar set of vibrations present when no human was nearby.  Nobody doubts for a moment the result of such an experiment - we can reasonably assert no statistically significant variations in the acoustic results with or without humans in earshot.


 * So the only way for there to be any kind of doubt or 'dilemma' here is to create artificial doubt as to the meaning of an arbitary English word. If we explain this dilemma to a speaker of the Wiki-ese language (I just made that up!) which has two completely different words for acoustic vibrations that are heard by humans and acoustic vibrations that are not heard by humans - then you would be utterly unable to create a dilemma in the mind of that person.  If you found someone who only spoke Pedia-ese (which happens to have just one word for "sound" that is completely unambiguously defined as "acoustic vibrations whether heard by human or not") - then you'd be unable to even describe the 'dilemma'.  So to the extent there is a dilemma at all - it would only be a question of "Why is the English Language so vague" - there is no deeper question here - we're well aware that our language is a little uncertain at times.


 * If we are forced to use this weird definition of sound (things that humans hear) - then we are thrown into a 'Schrodingers Cat' kind of situation where the tree both does and does not make a "sound" until someone decides to "observe" the sound by replaying or examining the recorded vibrations. Just because some bizarre philosopher decides to make a deliberate attempt to create confusion where there formerly was none doesn't make it so.


 * I hereby create a new dilemma for the ages to ponder - "Is the sky blue?" - oh and by the way, I've decided to define the word "blue" to mean - "the colour humans percieve in the 450–495 nm range but only when a dice is rolled and it comes up '6'"....Wow! - Deep eh? That'll keep the stupid philosophers arguing for another couple of centuries!


 * SteveBaker 01:04, 1 July 2007 (UTC)


 * Whoah, Steve, my buddy, my name-sake -- chill! :-)
 * That second definition is certainly not "mine"; I just offered it up to defuse the argument. And it wouldn't surprise me if there is some second definition (or some second word) out there, because: in the (almost equally silly and interminable) debate over whether animals feel pain, the "experts" on that question have managed to draw a distinction between "pain" and nociception, where nociception is the mere neural signal which even the dumb animals might feel, and "pain" is this fancy emotional thing that only we hoity-toity humans can feel -- and which we can feel even if there aren't any "mere neural signals" to induce it, i.e. if we're heartbroken or something.  Go figure.
 * The other way we could debate this (not that I want to) is to take the Schrödinger argument even further and stipulate that the forest has to be empty not only of sentient humans, but also their microphones and seismographs and computers. The question then becomes similar to another one which (for some reason) I used to get exercised about, namely whether it can be proved that the light goes out when you close the refrigerator door.  Now, you can come up with all sorts of bizarre hypothetical suppositions about how maybe it might undetectably not go out, but don't worry, I'm not going to trot them out now, because they all collapse instantly with but the barest touch of Occam's razor. —Steve Summit (talk) 01:31, 1 July 2007 (UTC)


 * Actually, defining "sound" as experiencial is very common.
 * "The sensation produced in the organs of hearing when the surrounding air is set in vibration in such a way as to affect these; also, that which is or may be heard;..." - Definition 1a in the Oxford English Dictionary.
 * "The sensation stimulated in the organs of hearing by such vibrations in the air or other medium." - Definition 1c in the American Heritage Dictionary.
 * In all reputable cases, they will also include definitions that are purely physical (i.e. vibration by themselves), but for most of human history man had no way to understand the physical process behind sound at all. It's not a matter of "creating confusion", but rather there was (and to some degree is) confusion about the nature of experience and the connection between physical reality and human perception.  Is the sky "blue", or does it only appear blue because humans have eyes with overlapping sets of visual receptors tuned to colors in the visible range?  Someone without those eyes might be trained to recognize that the wavelengths of light coming from the sky would be called "blue" by me, but they will never have the same experience of seeing blue that I do.  You are openly dismissive of philosophers for asking "does it make a sound", but would you be equally dismissive of those who ask "In what way is human perception of reality filtered and distorted through the limitations of our sense organs?"  Because both questions are part of the same field of enquiry with the first often being a prelude to the second.  Dragons flight 01:44, 1 July 2007 (UTC)


 * Ack! As always - I speak too loosely for the literal minded. I didn't mean to imply that no dictionary defines the word "sound" as "that which humans hear" - I meant to say that no dictionary defines it ONLY as that.  There is always another clause in the definition that also defines it as vibrations in the air (with the implication that humans don't have to be present).  A dictionary definition that only defined it for human hearing would be a travesty of the way the word is used...for example, we say that animals hear sounds - which would be a meaningless (and untrue) statement if the word meant only "that which humans hear".  If the word carries both meanings (as it should) then when a tree falls with no-one to hear it, it still makes a "sound" by the second meaning of the word.  Once you define the word clearly - the "dilemma" posed by this ridiculous philosophical nonsense simply evaporates.
 * There is certainly something to be argued that we know that human perceptions do not capture all of the information present in audio and visual phenomena. We don't hear all of the frequencies of sound that the tree makes when it falls.  We can't tell the difference between the blue of the sky (a mixture of a lot of different frequencies of light) and the "same colour" blue on a photograph of the sky on a computer screen - which is composed of just two frequencies of light.  Sure there are large discrepancies between what we see and what the world "truly is" - but these are again, very clearly explained and understood phenomena.  We know for absolute certainty that two humans do not necessarily percieve things identically. There are people who are colour-blind monochromats and dichromats - there are normal trichromats - but at least two different genetic variations on the red/green sensors - and there are a few (very few) tetrachromats.  We know for a fact that these people don't see the same 'blue' for the sky.  To imply a layer of mysticism and doubt is entirely unnecessary - for philosophers to "address this problem" like it was some big unsolved wonder of the universe is just a waste of time.  We already have a very clear answer.
 * Even within one person, we can clearly demonstrate that our perceptions of the world are not constant. If you haven't done it before - this is a literal life-changing experience.  Go to Gestalt psychology and look at the first picture under the heading "Emergence".  If you've never seen it before, it's just a bunch of random spots.  But if you EVER - even once figure out what the picture is - or if you read the text to the right of it - you'll never, ever in your life again be able to see it as a random set of spots.  You can come back to the picture years afterwards - and have forgotten all about Gestalt psychology - but never again in your life will you ever be able to see that picture as a random set of dots.
 * So not only do two humans percieve that set of dots differently - but one human percieves it utterly differently after 10 seconds of 'training' - and never loses that!
 * But this isn't some great mystical thing that is a 'dilemma' - it's just good solid science. Why debate whether the world truly is as we percieve it - when we know for absolute certainty that it's not?
 * SteveBaker 04:12, 1 July 2007 (UTC)


 * No one created any "bizarre" definition to assist philosophers in a "pathetic" attempt. My trusty 19 sixty-something Webster's Collegiate dictionary has several definitions for "sound" as a noun (besides the ones as a verb or adjective).  "The sensation perceived by the organ of hearing" is the first one, and requires a hearer (not necessarily human).  You might prefer a later one: "mechanical radiant energy that is transmitted by longitudinal pressure waves and is the objective cause of hearing." But again it requires a hearer. Otherwise it is just "mechanical radiant energy."  Similarly "light's" first definition is "something that makes vision possible."   A psychology book I checked left out the philosophy altogether and talked about sound energy. Of course if it is too high or low frequency for a human or other ear (bat?) to perceive it is vibration but not sound. Of course if the tree crashed into splinters, one of them might constitute a somewhat jagged "sound: an elongated instrument for exploring surgically body cavities." Edison 05:51, 1 July 2007 (UTC)
 * Please re-read the first paragraph of my previous reply. Note also the widespread use of the term "ultrasound" when referring to sound so high in frequency that even dogs, bats and so forth cannot hear it.  Still, it remains that philosophers are arguing only about the definition of a common English word - no deep revalations about the nature of man and the universe can come from it. SteveBaker 15:22, 1 July 2007 (UTC)

If "sound" is taken to mean the perception of hearing, then the question could be reworded "If a tree falls in the forest and no one hears it, does anyone hear it?" Pfly 06:11, 1 July 2007 (UTC)
 * Exactly...and if you choose the other definition for the word 'sound', the question becomes: "If a tree falls in the forest, does it produce mechanical vibrations if no member of the species homosapiens is proximate to the point of impact?"...to which the answer is very well known. In order to make this question anything other than trivial, you must rely on the ambiguity of the English language - it's not philosophy - it's just a silly pun.  It's about as interesting as "Do the British drive on the right side of the road when in France?" - which is merely a silly joke based on two differing dictonary definitions of the word 'right'. SteveBaker 15:32, 1 July 2007 (UTC)

I posted the original question, and I appreciate all of the input. But, my head is spinning. Let me re-phrase the question in a way that will make it easier for me to understand the answer. Thanks.

Scenario 1: I have normal unimpaired unobstructed hearing (e.g., I am not deaf, I am not wearing headphones, etc.). I walk into the woods and stand near a tree. That tree falls (away from me, not on me).

Scenario 2: I walk into the woods. I place a working tape recorder near a tree. I leave the area completely. While I am gone, a tree falls (away from the tape recorder, not on it). I later come back and retrieve the tape recorder.

Will the "stuff" (sound, noise, whatever you want to call it) that I hear on the tape recorder from Scenario 2 sound exactly the same as the "stuff" (sound, noise, whatever you want to call it) that I hear with my ears from Scenario 1? Thanks. (JosephASpadaro 06:37, 1 July 2007 (UTC))


 * The recorded sound would not be exactly the same because you'd be listening to it through loudspeakers and some kind of electronic amplification system. Assuming a reasonable-quality recording and playback system, it ought to be a reasonably similar sound. Pfly 06:56, 1 July 2007 (UTC)
 * Short answer, YES, as explained in original posts. --jjron 11:32, 1 July 2007 (UTC)
 * Actually, the short, medium and long answers should all be "Yes"! SteveBaker 15:22, 1 July 2007 (UTC)
 * Oh, another twist to this. Perhaps the tree is falling because it's died because all the air has been sucked out of the forest. Since there's no air that also explains why there's no-one there to hear it. And since there's no air it won't make a sound. No, stop it, this is all just getting too silly. ;-) --jjron 11:39, 1 July 2007 (UTC)
 * Nope - you're wrong. Vibrations would be transmitted through the tree trunk and the ground - so even this is not true for a scientifically broad definition of the word 'sound'. (To quote the first sentence of Sound:  Sound is a disturbance of mechanical energy that propagates through matter as a wave. - so no air is required for a falling tree to make a sound. SteveBaker 15:22, 1 July 2007 (UTC)
 * Umm, it was a joke; never mind... --jjron 02:37, 2 July 2007 (UTC)

Blood-sampling for measurement of sex-related hormones
How can we measure sex hormones and other sex-related hormones, like hormones related to sex-attraction and sex-excitement at the time of sexual intercourse, such as testosterone, adrenaline, etc.? In other words, when during the day and where in the body can we measure these hormones? After extracting the blood sample, how long it can be preserved by freezing and on which temperature? I hope you'll answer my question soon. Thank you 217.132.193.68 12:14, 30 June 2007 (UTC)


 * One of Robert Winston's programmes showed him measuring his blood testosterone levels during the England vs. Argentina 2002 World Cup match by placing a small piece of foam in his mouth, which was replaced every couple of minutes, and having the pieces of foam analysed in a lab (although you could do it with a titration and an anti-doping kit). I'd imagine that such an approach would work with most if not all hormones, and would be far easier to carry out than repeated blood drawings. Laïka  11:03, 1 July 2007 (UTC)

FGFR
When is there an overexpression of Fibroblast Growth Factor Receptor in our body, as in under what circumstances or any stimuli?


 * This sounds like homework. But maybe not, and I will assume you are just curious... we have an article about all of the following:


 * fibroblast
 * fibroblast growth factor
 * fibroblast growth factor receptor
 * Maybe the answer will be self-evident if you even very briefly skim any of these articles... Nimur 17:10, 30 June 2007 (UTC)

event horizon
Where does all the energy come from to keep the last image of something falling into an event horizon frozen on the surface? Surely there are only so many photons bouncing off it when it passes the event horizon- wouldn't they basically all be escaped or sucked in within a very short time?

Also what would happen if you sent a giant clump of antimatter into a black hole? A giant enough clump that not enough matter is left to trap light and maintain an event horizon. Would it still be considered a singularity even if the remaining piece of the black hole is still solid matter? --⁪frotht 15:05, 30 June 2007 (UTC)


 * Sounds like you're basing your definitions of an Event horizon off of science fiction rather than science. Any thing passing the event horizon would not be viewable to someone outside of it, since light wouldn't be able to escape.  Also, if you dropped a lot of antimatter into a black hole, you'd just be adding mass, not removing it.  The First law of thermodynamics still holds. --  JSBillings  19:25, 30 June 2007 (UTC)


 * From the viewpoint of a distant observer, time slows down for the object falling into the black hole. It is true that the distant observer will never see the object cross the event horizon. However, as it approaches the event horizon its image will undergo increasing gravitational redshift, so fewer and fewer photons with less and less energy reach the distant observer. Gandalf61 19:44, 30 June 2007 (UTC)


 * To amplify what the previous posted said: a black hole messes with time in a big way. Infalling stuff appears to be "frozen" only from the point of view of an outside observer, since time runs at very different rates very near vs. very far from a black hole. Regarding the second question, for stuff inside an event horizon, distinctions between matter, antimatter, and energy lie somewhere between irrelevant and nonexistent. If you dump anything into a black hole, you just end up making it bigger. --Tugbug 20:06, 30 June 2007 (UTC)


 * To answer the antimatter question more concretely: When matter and antimatter come into contact outside of a black hole, they produce gamma rays which then escape. The energy content of the gamma rays is the same as the total energy content of the matter and antimatter. If the same thing happened inside a black hole, the gamma rays wouldn't be able to escape, so all the energy would remain inside the black hole and its gravitational field wouldn't change. (Remember, in general relativity, all energy creates a gravitational field, not just energy in the form of matter.) —Keenan Pepper 21:37, 30 June 2007 (UTC)


 * So is it possible for a black hole to made of entirely energy, with little/no actual mass in the center? --⁪frotht 02:16, 1 July 2007 (UTC)


 * Mass-energy equivalence. Your question is nonsensical, you can't have energy without having mass and vice versa.  Inside a black hole, the distinction that humans usually perceive between matter and energy is basically immaterial.  Dragons flight 02:23, 1 July 2007 (UTC)


 * From outside the event horizon, you cannot tell how the black hole was created - whether it was from matter or antimatter or a combination of the two, or even from pure energy. You can only observe three parameters of the black hole - its mass (remember that energy also has mass, as Dragons flight says above); its charge and its angular momentum. This is called the No hair theorem. All other "information" about objects that have fallen into the black hole is lost. Gandalf61 12:46, 1 July 2007 (UTC)


 * I've asked this before, but while knowledgable people are watching, I'll try again: how is the no hair theorem consistent with (or, better, useful alongside) the notion that it takes infinite time in any remote frame for anything to fall into a hole? Shouldn't any hole just look like the collection of "almost-there" shadows of the things that have fallen (are falling?) into it, and thus have rather more than 3 scalar properties?  (Going further, how can we ever observe an extant hole at all?)  I have had a thought that perhaps the event horizon, growing as it will with the addition of mass, "meets" the infalling material and so causes it to actually vanish in finite time, but I haven't had this corroborated.  --Tardis 01:34, 2 July 2007 (UTC)


 * For those of us who only have one term of relativity, what is the "no hair" theorem? - Running On  Brains  00:53, 4 July 2007 (UTC)


 * Like Gandalf61 said above, the no hair theorem just says that from outside the black hole you can measure its mass (or equivalently, its energy content), its angular momentum, and its electric charge (and possibly magnetic charge if such a thing exists), and any quantities that you can obtain from them. So things like various quantum numbers, or whether the black hole contains matter or antimatter, can't be measured. As to how you measure it, you can determine the shape of spacetime (the "metric") outside the black hole, and this is determined by these three (or four) quantities.
 * As to Tardis' question, you're not seeing things that have already fallen into the black hole, since they take infinite external time to do so. Theoretically, if you had a good enough spaceship, you could swing in to orbit just outside the black hole's event horizon, grab something falling in, and pull it out again. The actual interaction of matter with the black hole (with the whole radius thing and whatnot) is probably a bit complicated due to the way spacetime behaves at the event horizon. Confusing Manifestation 01:51, 4 July 2007 (UTC)
 * You'd have to be pulling pretty strongly- the definition of the event horizon is that you'd need infinite force to pull anything out once it's that close. --⁪frotht 03:15, 6 July 2007 (UTC)


 * Now that we're talking about this, wouldn't it mean that matter (be it dark or baryonic) / energy never enters the event horizon? As time dilates more and more as one gets closer to the black hole, doesn't it eventually stop? If so, how can anything get "into" the black hole (besides the singularity's initial mass), if everything gets stuck in the accretion disk? If everything is in the accretion disk, then doesn't it become more massive, producing gravitational forces that attempt to tear the black hole apart? Tito xd (?!? - cool stuff) 00:59, 5 July 2007 (UTC)
 * The object falls into the black hole very quickly (for the average black hole it's less than a second past the even horizon) but from your perspective outside it appears to fall more and more slowly until it freezes just before the event horizon. After that, the light reflected off the object can no longer bear the strain and simply falls into the black hole itself. --⁪frotht 03:18, 6 July 2007 (UTC)

water purification of plants
how plants can discern the particles of substances and elements, with what special characteristic of them? and it would be nice if there is useful links and references.
 * It is a simplification to assume that plants purify toxins out of the ecosystem. In fact, biomagnification discusses the rapid concentration of heavy metals by accumulating in algae and upwards through the food chain - a convenient counterexample to the common idea of "purification".  However, wetlands do serve as a sort of eco-filter.  You may also want to read about wetlands and their function in an ecosystem.  "Denitrification is arguably the most important of these reactions because humans have increased nitrate worldwide by applying fertilizers."
 * How does it work? At the cellular level, facilitated diffusion is about the simplest mechanism that enables plants to "discern" particles; more advanced control and selection can be obtained with more complex cellular processes.  Plant anatomy discusses the structures in a plant; vascular plant discusses a more elaborate structural level.  Nimur 17:15, 30 June 2007 (UTC)

TV letterbox and 16:9 TVs
We have conventional 4:3 TVs. Some programs are in letterbox, for instance on The History Channel right now is one in an aspect ratio that I measure as 1.62. If we get a 16:9 TV (a 1.78 aspect ratio), will the picture fill the screen vertically, and have black bands on the sides? Bubba73 (talk), 20:26, 30 June 2007 (UTC)


 * It depends on your settings. Usually, Wide screens have settings for Normal: what a 4:3 looks like; Stretch: a 4:3 made to fit the entire screen; Zoom: zoomed in to the image, so it takes the entire screen, which is what wide screen format uses in my experience (which isn't much, I just own one, i'm not technically inclined with TVs), and zoom stretch, which is just painful --ʇuǝɯɯoɔɐqǝɟ 20:55, 30 June 2007 (UTC)


 * Thanks. That doesn't quite answer what I was asking.  On many susposedly 4:3 TV programs, they use a letterbox with a ratio of about 1.62, with black areas at the top and bottom.  Can you make the 16:9 TVs expand that vertically (and horizontally by the same factor) so that it fills the screen vertically and leaves a little black area on the sides?  Bubba73 (talk), 01:21, 1 July 2007 (UTC)


 * In other words, I want the picture to be in the proper aspect ratio and I don't mind black areas vertically or horizontally, but I don't want both. If a picture that is in letterbox on 4:3 screen is directly translated to a 16:9 screen, it would have black on all four sides.  I don't want that.  Bubba73 (talk), 23:17, 1 July 2007 (UTC)

Microwave oven accident
(silly thing to ask but) I've accidentally placed in my microwave oven some food which was rolled in an aluminium foil and paper container (one side paper, the other alu). It was touching the door, it caught fire and scolded the inside of the door. Is my oven now safe to use? From what the oven article says, I guess it is ie there won't be any wave leakage or something but i'd like your take. Thank you!


 * We can't give advice on something which could very well post a medical (and property) hazard. Your best bet is probably to buy a new one, they aren't so expensive that it's worth the risk IMO --ʇuǝɯɯoɔɐqǝɟ 20:53, 30 June 2007 (UTC)


 * Is that scolded is a typo for scorched or something? —Keenan Pepper 21:29, 30 June 2007 (UTC)


 * I assumed they meant scalded. --ColinFine 22:08, 30 June 2007 (UTC)


 * Generally, any damage to a microwave oven, especially the door, should be treated as a catastrophic failure; the door contains a very cleverly designed shield to prevent the microwaves from escaping, and damage to that means that the whole kitchen is potentially at risk from the possibly dangerous levels of microwave radiation (in particular, damaged microwave doors can cause cataracts). Replace it. Laïka  22:59, 30 June 2007 (UTC)


 * The door contains a metal mesh between two glass plates. As long as the metal mesh and the rest of the metal casing is fully intact, the microwave is safe. If there is any hole in the shielding, the microwave is dangerous. So if you just have a layer of ash on the inside of your door, clean it and thats it. There is no clever designed shield, unless you call a plate with small holes a clever design.


 * Your description does not convey enough information for anyone to evaluate the amount of damage or advise on the safety of using it. Check the instructions which came with the microwave for how to clean it, and ask the manufacturer for further advice. You could also take it to the store where you bought it and ask a technician there to inspect it. There are testing devices which can check for leakage from a microwave oven. A fire in the oven could have damaged the door such that microwaves could leak out when it operated. Edison 04:54, 1 July 2007 (UTC)


 * Besides the metal mesh, I would also worry about the rubber gaskets around the edge of the door. —Steve Summit (talk) 05:00, 1 July 2007 (UTC)


 * The TV show Mythbusters pretty much proved that it's almost impossible to damage a Microwave by putting metal in it, even balled up aluminum foil. If you were able to damage it (by attaching the aluminum foil to the inner metal wall of the microwave and running it for a few minutes), the only damage would usually be the magnetron, not the metal-mesh shield. So, metal in a microwave will create quite a light show, but unless there's damage to the mesh or the front glass is cracked, it should be perfectly safe. One test would be to put a stick of butter on a plastic plate outside the microwave and 2-3" in front of the door. Put the plate on top of something so that the height of the butter is roughly equal to the center of the door. Then put something, say a baked potato or anything that won't burn quickly in the microwave and run it for 5 minutes. Stay a few feet away while it's running. If the microwave is leaking, there will be noticeable melting on the side of the butter facing the glass. It's not a scientific test, but it's good for telling you if there's any energy leakage at the place where most people stick their faces. If you can't tell whether the mesh is damaged, definitely have a qualified technician look at it. It's always better to be safe. 97.82.247.200 16:07, 1 July 2007 (UTC)
 * The Mythbusters debunking of the myth of causing hazardous damage to a microwave by microwaving aluminum isn't truly relevant, unless they also tested setting the oven on fire ;-) Someguy1221 22:07, 1 July 2007 (UTC)
 * I recommend the microwave leakage tester by a qualified tech rather than the butter melting test. You might get cataracts from far less energy than it takes to melt butter. The mythbusters show is completely irrelevant as was pointed out. A fire in a microwave could damage the gasket and cause leakage. Edison 23:16, 1 July 2007 (UTC)

Hybrids different... how do you call this?
Hybrids may vary in phenotype, depending on the respective sex of the parent species. A Mule and a Hinny are different, as are a Liger and a Tigon. But how do you call this kind of differences? Are they investigated and analyzed? How do you call the science doing so? --Thick Peter 23:31, 30 June 2007 (UTC)


 * I'm not sure I understand the question, which may be why it's not attracting any answers. To the degree that differences are investigated and analysed it would just be the way any animal differences are investigated, chiefly by zoologists or by other biologists such as geneticists. I have not heard of any particular scientific discipline that deals exclusively with hybrid animals (or plants), and I very much doubt that one exists, although particular individual scientists may indeed specialise in this area. While hybrids attract a certain degree of interest for various reasons, remember that they are regularly sterile and therefore of somewhat less interest to most biologists. --jjron 12:24, 1 July 2007 (UTC)
 * You have answered the second part for my question, thx. For the first one:


 * Sexes are different in many species. You call this a sexual dimorphism.
 * Hybrids are often different, depending on which species is father resp. mother. You call this... well? A "hybrid dimorphism"? --Thick Peter 13:01, 1 July 2007 (UTC)


 * Just in case some of you didn't know, Homo Sapiens are Hybrids, according to one of the recent hypothesis.--nids(&#9794;) 13:10, 1 July 2007 (UTC)


 * That's, shall we say, a rather fringe idea which I wouldn't be placing too much credence in. Re the actual question it's rather interesting, I had never thought of that and don't know of any specific term for it. All I can think of is that it's just a form of variation, though I must say I do like your 'hybrid dimorphism' term. While it seems that 'hybrid dimorphism' is a real, if very rarely used term (try a Google search for it), it seems that even when used it may be just a contraction of 'hybrid sexual dimorphism'. --jjron 02:56, 2 July 2007 (UTC)