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August 13
Headphones
I have been thinking about what kind of headphones I want. I want the best pair of headphones I can get for under $200. I want low impedance, I want durability, I want comfort, I want terrific sound quality. Right now I have my eye on some Sony MDR-7506'ers after dying over them a month ago. I will be listening to rock, and classical, and I will use these headphones a lot. Thanks, — [Mac Davis] (talk)
- I like Etymotic, but you're probably looking more for over-the-head models. Are you looking for noise cancelling, or will these be for home use? I've tried some Bose headphones, and the sound and noise-cancelling is phenomenal. This pair is in your price range. Deltabeignet 20:58, 13 August 2006 (UTC)
- I would recommend looking where DJ equipment is found, for three reasons. A) DJs demand high volume and noise reduction, sturdiness of build, sound quality, and techno-modern appearance, and that's more variables than your average listener, or even headphone afficianado usually requires. B) There is a significant DJ community which supports a variety of high-quality brands. C) DJs generally don't have money to waste on gimmick products, so headphones marketed for DJs probably aren't as expensive as they would be if they were built with others in mind. freshofftheufoΓΛĿЌ 11:37, 14 August 2006 (UTC)
Bigger and blacker is better
Do black men statistically have larger penes, or is it just made up? — [Mac Davis] (talk)
- Have you looked at Human_penis_size#Race_and_penis_size?-gadfium 01:16, 13 August 2006 (UTC)
- I once heard that the English complain more about condoms being too small. Then again, such things may be caused by either the size of the penis or the size of the brain. DirkvdM 12:02, 13 August 2006 (UTC)
- Or condom companies knowing that a customer with an inflated ego is more likely to keep buying the ones that make him feel that he's "Extra Large". Confusing Manifestation 10:07, 14 August 2006 (UTC)
Libido
What hormones govern one's libido? Are each gender's totally different? — [Mac Davis] (talk)
- It's mainly testosterone, in both sexes. Anchoress 01:14, 13 August 2006 (UTC)
gender and fetal development
I've just read a review (The Globe and Mail - August 12, 2006) af a new book (The Female Brain by Louann Brizendine. In the review, this statement is made: "In the beginning, actually, we are all the same: the fetal brain is female". I believe that this statement is incorrect even though I have seen it repeated often in many different sources, I'd like to know the correct answer. From conception, as I understand it, all the cells of female brains contain two Y chromosomes and all the cells of male brains contain one X and one Y chromosome? Therefore, from the moment of conception, a male brain would be male and a female brain would be female wouldn't it? When speaking of fetal development, however, perhaps it is true that in the early stages of development, male and female brains do not appear much different until testosterone (as is stated in the review) influences that development. Please give me the straight information about this or direct me to a source which will do so. Thanks.
- That's probably a feminist talking. The brain really isn't "female" or "male," its just a developing brain. Woman is not the ultimate gender. — [Mac Davis] (talk)
See our sex differentiation article. The statement "the fetal brain is female" is misleading and inaccurate. It is a garbled version of pre-gene expression understanding of differentiation. The old version goes roughly like this:
- The fetal mammalian brain is undifferentiated. If exposed to testosterone from testes it becomes masculinized. Those brains not exposed to testosterone continue to develop without testosterone effect and become feminine. In a sense, there was no known difference between a brain destined to be female and a brain destined to be male before the testes start making testosterone at about the 7th week of gestation. In the late 1970s feminists made much of this, and this is the lineage of the statement you quote. However, it is certainly misleading, if not downright false, to claim that an undifferentiated 6 week fetal brain is the same as a female brain.
More recent molecular genetic research makes the statement even more ridiculously wrong, as it has now been shown that male and female brains express a number of gene activities differently even before testosterone levels rise enough to cause the differentiation described above. I would not believe anything else this author writes about biology. alteripse 02:02, 13 August 2006 (UTC)
And a point of clarification for our original questioner. You wrote, "all the cells of female brains contain two Y chromosomes", but you meant "all the cells of female brains contain two X chromosomes." (at least for humans!) - Nunh-huh 02:05, 13 August 2006 (UTC)
can this happen
can a star ever hit the earth?
- No. Every star except the sun is too far away. Things like comets or meteorites can hit the earth and destroy all life forever though. Hyenaste (tell) 02:17, 13 August 2006 (UTC)
Ever? Take a look at this website about galactic collisions and Interacting galaxy. --JWSchmidt 02:43, 13 August 2006 (UTC)
- Yes it could happen, but the chances are so small you would do a lot better to worry if your seat belt is fastened (but then again, that's true of almost every other risk, too). StuRat 03:21, 13 August 2006 (UTC)
- Actually, if you want to be technical, a star can never hit the earth. The gravity of the star would pull the earth towards it, not the other way around. Emmett5 03:41, 13 August 2006 (UTC)
- Unless it was a dwarf star. Hyenaste (tell) 03:48, 13 August 2006 (UTC)
- Actually, if you want to be technical, it doesn't matter who pulls who, the Earth and the star would be hitting each other. Besides, the Earth was here first.
- Where is "here"? In a universe with unknown boundaries filled with moving objects we have no fixed points of reference by which identify any one point, so identities such as "here" are completely arbitrary. Location in the cosmological context is entirely relative, so all one can really say is that two bodies — the Earth and Star X — are moving towards one another. – ClockworkSoul 07:33, 13 August 2006 (UTC)
- Is this an Earth first argument?
- Actually, if you want to be technical, it doesn't matter who pulls who, the Earth and the star would be hitting each other. Besides, the Earth was here first.
- Unless it was a dwarf star. Hyenaste (tell) 03:48, 13 August 2006 (UTC)
- I dont think any stars (or galaxies) are close enough to collide with the earth before it is absorbed when the sun entres the red giant stage. So no is the answer. Philc TECI 10:29, 13 August 2006 (UTC)
- You mean the ones we know of? The moment the Sun turn red giant is about 5 billion years away. Suppose a rogue star would travel at one millionth the speed of light (1000 km/h). It could then be 5 thousand lightyears away and still get here in time. At that distance it would have to be fairly sizeable for us to see it. So yes, it seems possible. DirkvdM 12:27, 13 August 2006 (UTC)
- So that's the answer. When the Sun turns red giant, it will hit the Earth, but only very slowly. --Heron 12:50, 13 August 2006 (UTC)
- The Sun will not absorb the Earth. So yes, it's possible that a star can hit the Earth. But the distance to even the nearest stars (besides the Sun) are huge, compared to the size of the stars, so it's extremely unlikely. --72.136.70.187 18:24, 13 August 2006 (UTC)
- Sorry, my browser logged me out. --Bowlhover 18:26, 13 August 2006 (UTC)
- The Sun will not absorb the Earth. So yes, it's possible that a star can hit the Earth. But the distance to even the nearest stars (besides the Sun) are huge, compared to the size of the stars, so it's extremely unlikely. --72.136.70.187 18:24, 13 August 2006 (UTC)
- Oh, thanks for that link, Bowlhover. I didn't realise that the Earth had an escape plan. --Heron 20:42, 13 August 2006 (UTC)
- I've always liked the idea that you could sort of 'ride' a small body out of the solar system after the sun collapses, might be the only way a human being is ever going to get anywhere near another solar system, of course human beings will be lucky to last another thousand years, let alone 3.5 billion years, not to mention in about 3 billion years the Andromeda Galaxy is going to be knocking at our doorstep, and will probably wreak havoc on a galatic scale, spark massive changes in predicted orbits and so on, might give a small planetesimal on the outer edge of our solar system a chance to 'surf' the waves of gravitation right out into deep space. Of course within a few million years of the collision, the massive shifts in gravitation would begin to spark rapid star formation and collapse, and waves of radiation would probably fill the resultant galaxy, and I imagine whatever super massive black holes happened to be sitting in the center of such a galaxy would go into their active phase and start chewing up everything in sight, which gives our cold dark planetesimal another escape route. Since the outer arms of that galaxy would probably fragment and be blown off into even deeper space, and what's left of our galaxy would light up like a Quasar. And that's probably about 5 billion years right there, and there goes the neighborhood. Of course, the current Human population is about 6.534 billion, so chances are the Earth will dump us like a bad habit long before any of that stuff happens. So it really doesn't matter, but it's fun to think about.--71.247.125.144 16:40, 15 August 2006 (UTC)
- If we really want to be remembered as a species, probably our best bet is to stick some recognizable feat of human civilization on as many Oort cloud objects as we can get to, maybe some sort of transmitter, or radioisotope, something to attract attention, while at the same time something that would be instantly recognized as not a natural phenomena. That way if it ever wandered into a stray galaxy some 80 or 90 billion years from now, someone might actually see it, of course that only works if by some fluke some debris from our galactic fender bender actually reaches another galaxy before the eventual heat death of the universe--71.247.125.144 16:40, 15 August 2006 (UTC)
- Longest run on sentance, ever oooOooOoh--71.247.125.144 16:40, 15 August 2006 (UTC)
- If we really want to be remembered as a species, probably our best bet is to stick some recognizable feat of human civilization on as many Oort cloud objects as we can get to, maybe some sort of transmitter, or radioisotope, something to attract attention, while at the same time something that would be instantly recognized as not a natural phenomena. That way if it ever wandered into a stray galaxy some 80 or 90 billion years from now, someone might actually see it, of course that only works if by some fluke some debris from our galactic fender bender actually reaches another galaxy before the eventual heat death of the universe--71.247.125.144 16:40, 15 August 2006 (UTC)
- I've always liked the idea that you could sort of 'ride' a small body out of the solar system after the sun collapses, might be the only way a human being is ever going to get anywhere near another solar system, of course human beings will be lucky to last another thousand years, let alone 3.5 billion years, not to mention in about 3 billion years the Andromeda Galaxy is going to be knocking at our doorstep, and will probably wreak havoc on a galatic scale, spark massive changes in predicted orbits and so on, might give a small planetesimal on the outer edge of our solar system a chance to 'surf' the waves of gravitation right out into deep space. Of course within a few million years of the collision, the massive shifts in gravitation would begin to spark rapid star formation and collapse, and waves of radiation would probably fill the resultant galaxy, and I imagine whatever super massive black holes happened to be sitting in the center of such a galaxy would go into their active phase and start chewing up everything in sight, which gives our cold dark planetesimal another escape route. Since the outer arms of that galaxy would probably fragment and be blown off into even deeper space, and what's left of our galaxy would light up like a Quasar. And that's probably about 5 billion years right there, and there goes the neighborhood. Of course, the current Human population is about 6.534 billion, so chances are the Earth will dump us like a bad habit long before any of that stuff happens. So it really doesn't matter, but it's fun to think about.--71.247.125.144 16:40, 15 August 2006 (UTC)
4G networking and application
Would someone plz tell me about the networking techniques involved in 4G mobile communication?
- This question may be more appropriately posed at the Computing/IT Reference desk. --LambiamTalk 02:53, 13 August 2006 (UTC)
Animals with weird names
Are there any animals with weird names other than Proceratium_google, Goldenpalace.com_monkey, and Pachygnatha_zappa? Thanks! :) -Ravedave 05:57, 13 August 2006 (UTC)
- Meh. It's gonna be a long list. But just cuz I don't have a date tonite, I think Homo erectus is a strange name, as are woodpecker, titmouse, and booby. Anchoress 06:00, 13 August 2006 (UTC)
- how about: [[1]] Adambrowne666 09:29, 13 August 2006 (UTC)
- Also: atlascopcosaurus - I like your examples, though, Ravedave, I'd never heard of them Adambrowne666 09:33, 13 August 2006 (UTC)
- Penis worm appeals to my inner teenager, as do bustards. I also like my boobies blue-footed. HenryFlower 09:52, 13 August 2006 (UTC)
- GoldenPalace.com Monkey: yikes, sponsored naming of a species? "This animal was brought to you by a casino?" What's next? Could you put your baby's name up for auction? Luckily my day is saved by the fact that the article speaks of 'pairs of titties' and even 'male titties'. :) DirkvdM 12:41, 13 August 2006 (UTC)
- Would you care for some blue tits with your spotted dick ? (OK, that last one is more of a food, but I couldn't resist.) StuRat 08:52, 14 August 2006 (UTC)
- Just imagine what happens if they ever change their ___domain name--71.247.125.144 14:44, 13 August 2006 (UTC)
- Does this count as weird: Stephen Nash's Titi Callicebus stephennashi? I remember reading an article about species that had been given weird names just for the humorous effect, which had quite a few examples. --LambiamTalk 17:39, 13 August 2006 (UTC)
- Dracorex hogwartsia was named by children recently. Rmhermen 18:43, 13 August 2006 (UTC)
- I think this must be the articlre mentioned above: http://www.nytimes.com/2005/02/20/weekinreview/20foun.html?ex=1266642000&en=072f74ff6a4493dd&ei=5088&partner=rssnyt I found it while googling for a mention I saw once of species names ending in tomii, dickii, and harrii, though it's not the article I was thinking of, it seems relevant. Malcolm Farmer 19:37, 13 August 2006 (UTC)
- Supersaurus always struck me as funny. --Ginkgo100 talk · contribs · e@ 22:10, 13 August 2006 (UTC)
Timber rattler= "Crotalus horridus horridus." Sounds like he made a bad impression on some naturalist. There is an extinct snake species named "Montypythonoides riversleighensis."Edison 17:42, 15 August 2006 (UTC)
For some reason, Scrotum humanum never really caught on. Still, as mentioned above, there are the everlasting favorites of elementary school biology, the tits and the boobies. —Ilmari Karonen (talk) 18:40, 15 August 2006 (UTC)
- Anyone up for a crappie meal ? StuRat 19:37, 15 August 2006 (UTC)
- I don't know why, but Felis cattus domesticus has always seems funny to me. Like they've just taken normal words and added "us"s. Aaadddaaammm 09:51, 16 August 2006 (UTC)
the doctors round mirrors
what are those round mirrors that were attached to a headband which doctors wore used for and do they have a name?
- They were used for indirect laryngoscopy (before direct laryngoscopy became commonplace). Indirect laryngoscopy involved the use of a small laryngeal mirror (not unlike modern dental mirrors) that was inserted into the throat, in combination with the head mirror you speak of (used to illuminate the smaller mirror). If they had a name more specific than "head mirror", I don't know it. - - Nunh-huh 06:40, 13 August 2006 (UTC)
Just to make it a little more clear - the little mirrors that you normally see perched on their heads in pictures, when used, are swung around to cover their eye - there is a little hole in the center to see through. A light source was placed pointing at the mirror which reflected the light forward wherever they were looking (such as the mouth). Although some ENT doctors still use them, they have largely been supplanted by headlamps which perform the same purpose. InvictaHOG 00:04, 14 August 2006 (UTC)
Physics
Hello all. I'm studying for a test tomorrow, and this particular question has me stumped- i have bad notes, and the text book is even worse.
A box of mass 20 kg is dragged along a rough horizontal floor by means of a rope held at the angle of 30 degrees with the horizontal. The force of friction between the box and the floor is 50N. Uf the force exerted along the rope is 350 N, what is the net horizontal force on the box? What is the accelreation on the box?
I would like to know what formual to use, and what adjustments i would need to make. Thanks in advance.Cuban Cigar 08:53, 13 August 2006 (UTC)
- First you have to know how to how to break down the diagonal force into two forces: one would be vertical, and the other would be horizontal.
- You can do it by trigonometry. You know one angle and the length of the diagonal of a right-angle triangle. You can calculate the horizontal using cos(30°)*350.
- You can do it by using Pythagoras's theorem.
- If you know that the height of an equilateral triangle is approximately (1.732/2) times the length of one of its sides, you can use that instead. An equilateral triangle has angles of 60°, so imagine one that's been cut in half. (The square root of 3 is approx. 1.732.)
- Next you have to know that two forces that act on the same object, but in opposite directions, cancel each other out. (Assuming the object doesn't spin or anything.) If the forces are in opposite directions but they don't equal each other, subtract the weaker force from the stronger force. That's the strength of the net force. The net force will be in the direction of the stronger force.
- Next you have to know that a Newton is a measure of force, which is mass (in kilograms) multiplied with acceleration (in metres per second squared).
Good luck. --Kjoonlee 09:47, 13 August 2006 (UTC)
I know some of this, but what really stumps me is the force between the object and the ground is 50N.
- The friction (50 N) will counter the horizontal pull by its size of 50 N. So you should subtract it from cos(30°)*350. The results of that will be the net horizontal force acting on the box. :) --Kjoonlee 09:56, 13 August 2006 (UTC)
- Well, to be honest, I *think* that's correct, but I'm not sure about the effects of friction. Will 50 N of friction really result in 50 N of horizontal force in resistance to the pull? Maybe I should read Friction. --Kjoonlee 10:02, 13 August 2006 (UTC)
- Yes it will, because that's just what it means. The force of friction is by definition the force you have to overcome while dragging the object. If you exert a larger force, the object will accelerate. --LambiamTalk 17:50, 13 August 2006 (UTC)
- Well, to be honest, I *think* that's correct, but I'm not sure about the effects of friction. Will 50 N of friction really result in 50 N of horizontal force in resistance to the pull? Maybe I should read Friction. --Kjoonlee 10:02, 13 August 2006 (UTC)
50N will just be subtracted from the net force, it gives me the right answer. Thanks to everyone who helped.
How many atoms are there in a cell?
Aproximately... Thanks.
- Please suitly emphazi, a human cell, an animal cell, a plant cell, a brain cell, a sex cell..... Benbread 11:06, 13 August 2006 (UTC)
- A cellular tissue is composed mainly of water. Water molar mass is 18.02g/mol, which means that single molecula of water weights .
- "Typical cell mass 1 nanogram...", therefore signle cell has .
- Water molecula is composed of three atoms, so single cell has about atoms. Michagal 11:13, 13 August 2006 (UTC)
- Thats more atoms in a cell than miles to the nearest star (not the sun) and back 250 times, and the same number as 20% of the grains of sand on the earth, or The worlds population multiplied by 2 million if random QI facts help you comprehend the magnitude of that number. Philc TECI 11:23, 13 August 2006 (UTC)
- What's with the "moleculae"? I've never heard that term before. Aaadddaaammm 09:54, 16 August 2006 (UTC)
Spaced out link
In answer to a question above, I made a link to a Dutch Wikipedia article, with a description that started with 'In', but the 'In' disappeared. Here's the format: [url|In ... bla bla]. This effect disappeared when I added a space, thus: [url| In ... bla bla]. Here are the real links (see source):
Any idea what caused that? DirkvdM 11:52, 13 August 2006 (UTC)
- wikisyntax? You don't put pipes (|) in external links, the link is separated from the description with a space (that's unambiguous since spaces do not appear in urls, they are rendered as '%20'). dab (ᛏ) 12:06, 13 August 2006 (UTC)
- In an exolink you should not use a pipe but a space to separate the url from the text rendered:
- (When you hover on your first link, you'll see that "|In" is taken to be part of the url.) Alternatively, use a wikilink like this:
- --LambiamTalk 17:15, 13 August 2006 (UTC)
- Silly me, I knew that. DirkvdM 10:16, 14 August 2006 (UTC)
Caffeine in breast milk
How long does it take for caffeine to enter breast milk after ingestion and/or how could one test for its possible impact in a breastfeeding baby? Is it possible a mother having one cup of tea could affect her baby soon after? We've googled this, but get contradictory answers. Thanks in advance. Adambrowne666 12:07, 13 August 2006 (UTC)
The half life of caffeine in humans is around 5-7 hours, but this is extended in pregnant women (18-20 hours), women on contraceptives (13 hours) and newborn babies (30 hours). caffeine is completely absorbed form the stomach within 45 minutes, and is widely distributed, which means is likely to be in breast milk. the test for caffeine in a newborn would be pretty drastic, i imagine a blood test or similar, but a test of the breast milk would be easier. i recommend reading caffeine, and talking to a doctor. Xcomradex 12:31, 13 August 2006 (UTC)
- I would suggest that the mother gives up caffiene altogether (I would suggest this for most people) since like a lot of other drugs, the body becomes tolerant/dependant after a while and you receive no additional benefits from further drug use other than to achieve the same level arousal that a normal person has from day to day who does not use caffeine. --130.161.182.91 14:07, 13 August 2006 (UTC)
- Why does the word 'addicted' change to tolerant/dependant when we're talking about legal drugs? DirkvdM 10:19, 14 August 2006 (UTC)
On the other hand, caffeine is used as a respiratory stimulant for newborn infants with apnea. The amount passed in breast milk is trivial and harmless. alteripse 18:21, 13 August 2006 (UTC)
- Thank you! :blows kisses to alteripse:. Anchoress 20:02, 13 August 2006 (UTC)
- It makes me feel all fuzzy inside when people read and/or quote text that I wrote. Thanks for making my hour! – ClockworkSoul 05:01, 14 August 2006 (UTC)
Thanks, all Adambrowne666 00:25, 15 August 2006 (UTC)
Anecdote re: speed of transfer from mother's digestive tract to her bloodstream to breast milk: a new mom went out to dinner at a restaurant and ate food containing a lot of ginger, garlic, and onion. Within an hour, she started to breast feed the baby, who was always a good feeder, but who screamed in outrage at the taste of the milk. Then tried to nurse again, baby screamed again. It was ok by the next day, but the mom kept apologizing to the baby all night. Or maybe the milk was still garlicky the next day but the baby had acquired the taste.Edison 17:56, 15 August 2006 (UTC)
Scientific Journal Access Through Wikipedia?
Is it possible for Wikipedia to subsribe to scientific journals (particularly review ones - since these aren't "original research") as an institution so that its member could improve it better? --130.161.182.91 14:03, 13 August 2006 (UTC)
- I doubt it, Journal Access is usually on the expensive side, and this is, for the most part, a non-for-profit site.. also usually Journal Access is usually authorized by either IP or passcode, since wikipedia can't provide an IP to it's users, and since a password would never remain private, I'm just not sure how it could be made to work. Besides, I have Journal Access through my university, and I assume I'm not the only one who does--71.247.125.144 14:41, 13 August 2006 (UTC)
- I'm not sure how the access could be licensed to be distributed to editors, either. Would be nice though. --Ginkgo100 talk · contribs · e@ 22:16, 13 August 2006 (UTC)
- Note that WP:NOR only applies to people attempting to publish their own original research on Wikipedia. It's perfectly fine to cite original research that's already been published in a journal. Citing OR is good, including it is bad. —Keenan Pepper 00:55, 14 August 2006 (UTC)
If you are not already aware, there are many free full-text journals and collections of research papers avaiable on the web. A random selection of some of my collection of links about this:
http://cogprints.org/perl/search/simple
http://www.citebase.org/search
http://ideas.repec.org/search.html
My favourite site is Citeseer, which deals with a wide range of things. I do not know if there is a wikipedia list about free journals, but their ought to be. 81.104.12.50 21:00, 15 August 2006 (UTC)
Diesel
What products form after diesel has been burnt?
- Combustion of hydrocarbons always yields carbon dioxide and water. Additives and incomplete combustion result in other products as well. Isopropyl 14:48, 13 August 2006 (UTC)
- carbon dioxide, water, incomplete combustion (anything except a bright blue flame with no smoke) also leaves carbon and carbon monoxide. Philc TECI 15:24, 13 August 2006 (UTC)
- Assuming you are asking about the differences in combustion products versus gasoline engines, classic diesels engines produced a fair amount of soot, although modern diesels burn much more cleanly than their predecessors. StuRat 08:42, 14 August 2006 (UTC)
Common name for Gordionus violaceus
Does anyone know what is the common name for Gordionus violaceus?
- I can't find a name for it, but if it helps, it Gordiona seem to be parasitic worms, and here is callasified as a horse hair worms. Philc TECI 18:14, 13 August 2006 (UTC)
- I doubt the species has a common name. We have an article on Nematomorpha. --LambiamTalk 20:36, 13 August 2006 (UTC)
- Assuming that violaceus refers to the colour, you could try calling it the "Violet horse hair worm". --LambiamTalk 20:43, 13 August 2006 (UTC)
kineto baric force and biefeld brown question
I have heard of something called a kineto-baric force that can move things useing electric fields and produce pressure. apparently its similar to electrokinetics except it needs no conductor and can only push things i think. I dont understand physics so could someone explain it to me in simple terms. Also does anyone know if this is mainstream accepted as i can find no skeptical or sites disproving it. It doesnt seem like anti-gravity stuff though, just another method of electro-propulsion. here are the links
http://science.radioelectronics.biz/electrokinetics/electrokineticPropulsion.html
http://www.rexresearch.com/zinsser/zinsser.htm
http://jnaudin.free.fr/lifters/files/ElectrograviticsElectrokineticsValone.pdf this has a mention of its relation to electrokinetics
There is a section on this website http://www.seaspower.com/Movingbeyond-LaViolette.htm "Kineto-baric Field Propulsion. German scientist Rudolph Zinsser discovered that sawtooth electromagnetic waves could be made to push distant objects. He produced a radio tube circuit that transmitted 45 megahertz radio waves having a sharp rise and gradual fall. His experiments demonstrated that these waves could exert impulses of up to 104 to 105 dyne seconds, which is equivalent to the application of about 1 to 3 ounces of force for a period of one second. He found that this force could be generated with an amazingly low input power, the output-force–to–input-power ratio surpassing that of conventional propulsion methods by several powers of ten. His projections imply a thrust of 1350 pounds force per kilowatt."
Secondly could the biefeld brown effect move non conductive substances like plastic or stone if a means to cause the ion wind, or thrust could be produced on its surface?
Thank you for your time Robin research
- "Kineto-baric force" seems to be a term unknown to physics (just did a tiny search), but this sounds rather like a more recent claim by Eugene Podkletnov. Be this as it may, if you read the talk pages at Wikipedia:WikiProject Physics-Wikipedia:WikiProject Pseudoscience you'll see that there has been quite a bit of unflattering discussion of several of the other topics discussed at some of the websites you cited. At least three of the four websites you mention can probably be safely regarded as "fringe-science"/cranky websites, as I would think should be fairly obvious:
- rexresearch.com says that it promotes "suppressed/dormant/emerging science, inventions, technologies, experiments", which is a pretty good hint that stuff discussed there may not be mainstream :-/
- seaspower.com says that "Space Energy Access Systems, Inc. (SEAS) is in the process of identifying and testing new technologies that claim to be over unity"; see perpetual motion machine for the meaning of "over-unity"; I hardly need add that proposals which would violate of the laws of thermodynamics are highly unlikely to belong to the canon of generally accepted mainstream science;
- Paul LaViolette, the fellow mentioned in the page you cited, is a "UFO researcher"; Etheric stargate says that it promotes "Zodiac cryptogram and books and scientific discoveries of Paul LaViolette on interstellar communication, cosmology, mythology, ether physics," and Starburst Foundation claims "the closing of the last ice age our ancient ancestors endured one of the most lethal global catastrophes to have occurred in the course of human history."
- jnaudin.free.fr says "Dear new explorers and experimenters, You are WELCOME in the JLN Labs web site dedicated to the search of Free-Energy solutions..."; note that "free-energy" as in "low to no-cost energy", especially alleged extraction of vacuum energy to do useful work, belongs to the "over-unity" fringe and is certainly far from the mainstream; note that this website has also promoted MEG, another putative over-unity device.
- See also
- Biefeld-Brown_effect-Reactionless drive-Lifter (ionic propulsion device)-John Hutchison-Teleforce-Free energy suppression (a conspiracy theory) and their talk pages (among others)
- List of pseudoscientific theories#Physics
- Crank dot (not often updated, but gives some idea of the amount of stuff which is "out there")
- Summing up: it would be a serious mistake to assume that just because you can't find comments on weird topic X at a mainstream website like The National Academies (formerly the National Academy of Science), that X must be mainstream science! I would hope this commonsense principle would be obvious, but took the trouble to reply since it seems that it might not be.---CH 23:54, 14 August 2006 (UTC)
Why wet things are dark
Hi, why are they? Whenever I wet a napkin with a "clear" liquid - water - it darkens. Why on earth? Thanks! -- 88.91.136.190 18:09, 13 August 2006 (UTC)
- Assuming you have a flashlight or something ;-), probably because water refracts light, changing the frequency of reflected light? Anchoress 20:04, 13 August 2006 (UTC)
- Read The Straight Dope's answer, then come back here if you need a second opinion. --Heron 20:24, 13 August 2006 (UTC)
- Here is a second opinion already: more light goes through (as you can see when you look through the wet cloth to a light source – the wet spots appear lighter), and therefore less is reflected. And that is because the light bounces less (not more). Third opinions, anyone? --LambiamTalk 20:30, 13 August 2006 (UTC)
- The same thing is true of things that are wet while being opaque (e.g. wet paint), so I don't think it has anything to do with refraction. I always assumed that the chemical properties (or I guess colloidal properties) of the molecules of water that interact with the other material are less transparent to light, and thus appear darker. freshofftheufoΓΛĿЌ 03:13, 14 August 2006 (UTC)
- This was asked before, but those answers don't satisfy me. My explanation was that dry cloth scatters the reflected light because of all the tiny hairs on it. Those will get flattened (stick to the cloth) when wet, so the reflection is more directional. most of the time you will not look at the cloth in exactly that angle, so it appears darker. But I tested this and I didn't find the brighter reflection that should be there at the right angle, so I didn't dare give that answer. I'm being a little bolder this time. DirkvdM 11:30, 14 August 2006 (UTC)
- This may be a stretch, but it's not completely off the wall. A lot of the color in textiles come from chemical dyes, which are subject to oxidation and reduction. Perhaps the presence of water induces a reduction reaction, dulling the dyes. Thus, when you get your cloth or paper wet, it becomes darker. This reaction is reversible, though... detergent operates by releasing an oxidizing agent to re-oxidize the dyes, hence so much commercial advertisement for "brighter colors" after washing. Nimur 16:43, 14 August 2006 (UTC)
- Thanks for many, yet few answers. I do urge you to take into account the darkening of wet wood, so the thesises regarding dye can be ignored, or so I think. There was one answer here that appealed to me, the "first second" opinion. To my limited knowledge, one more easily sunburns when bathing. The question is just if that is caused from being wet, plus the limited depth of one's skin under water - or simply from the light bouncing off the water, and striking the body which is so very close. Now, whatever way one looks at this, LIGHT IS LOST. It may be absorbed by the wettened material at a greater rate than before... I really don't know the answer to this. Can Oxford be contacted? 88.91.136.190 18:07, 14 August 2006 (UTC)
- Is sunburn increased when you are just wet? Or is it when you are in the water, thus getting a double-dose of UV as it gets reflected off the surfaces around you (similar to snow blindness)? freshofftheufoΓΛĿЌ 18:46, 14 August 2006 (UTC)
- I suspect that being wet makes you feel cool and thus stay in the sun longer. If dry, you would get hot and go indoors before getting sunburned. StuRat 20:48, 14 August 2006 (UTC)
- Being wet doesn't make you sunburn faster. Being on or near water does, however.Anchoress 21:14, 14 August 2006 (UTC)
- I suspect that being wet makes you feel cool and thus stay in the sun longer. If dry, you would get hot and go indoors before getting sunburned. StuRat 20:48, 14 August 2006 (UTC)
- It's an interesting question. Also, why does a white bird feather go grey when you dip it in clear acohol? It has to do with the index of refraction of the materials that the light travels through, as well as on the arrangement of the molecules in the material, which can alter reflected or transmitted light according to the differing interfaces and the distances between them. Reflection depends on differences in index of refraction. When you change the air/material interface to a water/material interface then the difference in refractive indices decreases, so there is less scattered reflection of light. Structural colour (as opposed to pigment) effects will also alter as the diffraction of light changes, so that phenomena such as colour caused by constructive interference will change. On top of that, the light reflected from the molecules in the material has to pass throught a water/air interface back to your eye, which reflects some of it back into the material. In the end, yes, more light "stays inside" and less comes back at you, and the light that does return will have a different "wave composition" from when the material is wet. You can observe some of these physical effects if you change the "wetting agent" from say water to alcohol to colourless oil. To add to the above, pigments may change their light absorption properties when they "get wet". --Seejyb 21:40, 14 August 2006 (UTC)
The reason that you sunburn quicker in the water is because of the compression of light caused by the waves. You know when you see that moving pattern of sunlight on the bottom of a pool, where the waves compress/rarefact the light because of the shifting angles of incidence on the surface? These magnifications intensify UV and Infared light also, burning you faster. As for the paper towel, i think that in THAT case the color change is mostly due to the tiny fibers being flattened. --Classic1977 09:43, 6 September 2006
Questions about "self surgery".
Since our article is a bit devoid of the information I seek: What, exactly, are some useful methods for self surgery? Like, how to fix your own dislocated shoulder, or how to extract a foreign object from your abdomen, or how to treat an infection in the wilderness.
Actually, does Wikipedia have like...A WikiSurvival project or something similar, for questions much like this? --Abnerian 22:35, 13 August 2006 (UTC)
- Any instructions that could make it easier for people to do something as blatantly hazardous as performing surgery on themselves would probably be a legal liability. But you might try googling 'wikisurvival' or something, it might exist elsewhere. And I'm sure there are lots of sites that feature survival first aid etc.Anchoress 22:38, 13 August 2006 (UTC)
- One should be able to treat dislocation (medicine) without resort to surgery, but, as our article states: Such manipulation should not be attempted without sufficient training, as it is possible to greatly increase the severity of the injury through improper attempts at care. For a shoulder you will need extra training because you can't perform this in the usual way on yourself anyway. For surgery, it helps to have some insight into human anatomy. This is also true for self-surgery. Further useful stuff is some surgical instruments, including needles for sewing up afterwards (don't forget the surgical yarn), ways of sterilizing them, materials for making the neighbourhood of the incision antiseptic, materials for handling and stopping the flow of blood, and for bandaging. Roughly speaking, there are no methods that are specifically useful for self-surgery; the best methods are the same ones used for surgery in general, except that the patient must remain conscious, or else the surgeon too passes out. --LambiamTalk 23:37, 13 August 2006 (UTC)
- For dislocation, you really need somebody else to do it for you while you scream in pain. — [Mac Davis] (talk)
- Not for Jack Bauer. --mboverload@ 02:49, 14 August 2006 (UTC)
- I once saw someone in a movie set his dislocated shoulder by wedging his arm between branches and then throwing his body away from that. Might work in principle, and if you're alone in a survival situation it might be worth a try because you'd be useless with a dislocated shoulder. The SAS survival handbook doesn't tell. It just says to put your foot in the patient's armpit and pull. I don't see anyone doing that to themselves. Then again, autofellatio seems to be possible, so who knows. :) DirkvdM 11:43, 14 August 2006 (UTC)
- Oh, and my mother once dislocated her little toe, causing it to point sideways. The way she told this, she 'simply pushed it back'. DirkvdM 11:46, 14 August 2006 (UTC)
How to relax my over-exercised muscles without drinking alcohol?
I have ethical objections to alcohol as I've known three or four drinkers who have ruined theirs and other peoples lives because of it. Also its bad for your physical and mental health. However after taking a lot of exercise over the past few days my muscles are very tense and ache slightly. Is there anything else that I could eat or drink that would relax them please? I am not into massage. Thanks.
- Maybe smoke something? It is normal, by the way, if your muscles feel tense after much exercise; it does not necessarily mean they are actually not relaxed. For some people a hot bath helps, although others report it aggrevates the condition. The best remedy is a couple of good nights of sleep. --LambiamTalk 23:42, 13 August 2006 (UTC)
- Just rest. Sleep is probably the best, (and cheapest!). P.S.:(did I read "taking exercise" right? Do we need to have Exercise (drug)?) — [Mac Davis] (talk)
- The expression 'to take exercise' is a turn of phrase common in the UK. Anchoress 00:31, 14 August 2006 (UTC)
- Though I'd buy it if they sold it! freshofftheufoΓΛĿЌ 03:01, 14 August 2006 (UTC)
- Its like taking tea and scones albeit with a bit more sweat involved. Rockpocket 06:11, 14 August 2006 (UTC)
- That may depend on the tea and scones. DirkvdM 11:59, 14 August 2006 (UTC)
- Its like taking tea and scones albeit with a bit more sweat involved. Rockpocket 06:11, 14 August 2006 (UTC)
- Though I'd buy it if they sold it! freshofftheufoΓΛĿЌ 03:01, 14 August 2006 (UTC)
- The expression 'to take exercise' is a turn of phrase common in the UK. Anchoress 00:31, 14 August 2006 (UTC)
- Thanks for the alcohol-education. We didn't know that it can develop into a bad habit. But you finally got around to an actual question, so I'll give an answer to that. Meditation. What I do is lie down on bed and put a folded towel in my back (not too thick) and neck (getting that right takes practise because the sensation changes as you relax more). Then, first I tense up the muscles in my toes. Next, I very gradually let the tension move up to my ankles, legs, body, neck, and then down to my fingers, where I let it 'flow out of my body' (it actually feels like that). Then I focus on relaxing the muscles in my toes (this is a bit harder, but somehow the preparatory tensing helps) and then up again, through my body and out through my fingers. This whole process takes a minute or two. After that, my muscles are very relaxed and I can start meditating. Provided the towel in my neck doesn't feel wrong, as a result of which I have to rearrange it, which ruins the effect. The more experience you get with this, the better the effect will be. Same for the meditation itself. But that makes too much sense to point out. :) DirkvdM 11:56, 14 August 2006 (UTC)
- Have you tried ibuprofen or naproxen?Tuckerekcut 21:03, 14 August 2006 (UTC)
- You are most likely asking about delayed onset muscle soreness (DOMS). Incidence and severity reduced by a gradually increasing exercise regime, and by eating after exercise. Also by NSAIDs. Opioid analgesics reduce the soreness only for as long as they would work for any injury. Local rubs like methyl salicylate reduce the discomfort by couter-irritation, but recovery is not hastened. The natural course of DOMS is not reduced by massage, stretching, homeopathy, local heat or cold, or electrical stimulation. --Seejyb 22:03, 14 August 2006 (UTC)
- Well answered, Seejyb. BenC7 02:15, 17 August 2006 (UTC)
Drink at least 20 oz of water after exercise; eat after exercise, especially protein, salt, and carbohydrates. Eat something like pasta with a chunks of steak on top, seasoned with salt. Use ice or a cold pack directly onto the sore muscles, followed by the high heat of a steamy shower. If you are not taking a multivitamin daily, start taking one. Do not rely on creams or expensive store bought products, this works just fine if you follow the above directions. I take Kyokushin Karate and have encountered many a sore muscle and tried many 'remidies'...the simpliest things always work, believe me. --69.138.61.168 03:51, 15 August 2006 (UTC)
- Straight after exercise jump into icy water, it helps with the recovery process. Einstein's shadow 11:47, 17 August 2006 (UTC) (Copied from below by 68.100.203.44 05:45, 19 August 2006 (UTC).)
August 14
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casimir effect scale up
Can the casimer effect in theory if not practice yet be scaled up in size and effect range? could we in theory make a repulsive or attractive force from it that could act on larger objects? Is there debate on this subject or is it a flat out no. How then if not by this are scientist proposing right or wrong to produce propulsive force from vacuum energy -- Restless
- No. In the Casimir effect, two very closely spaced neutrally charged parallel electrically conducting plates mutually attract because their presence changes the mode structure of the quantum zero point field (ZPF) relative to free space. If the plates are a distance d apart, the force per unit area <cool math stuff I couldn't get to work, sorry> is the reduced Planck’s constant and c is the speed of light in vacuum. The attraction between the two parallel plates can be understood in terms of the pressure of zero-point energy being greater outside the two plates, than in between—the plates snap together. This force is so so small. That is why the Casmir effect could never be scaled up—the mass of the plates would be greater, while the energy pressure continues to stay the same. ...unless you could get them closer and closer together. What would be that limit? Probably the Planck length Where is the article on the Casmir effect?? — [Mac Davis] (talk)
What if you could somehow increas the radiation pressure of the zero-point field in one area, would that be able to cause a larger version of the casimir effect? you also never aswered how people are trying to produce propulsive force from zero point energy. restless
- Look up for my response to a poster inquiring about some cranky stuff he found at some websites which promote "free energy from the vacuum schemes". Basically, vacuum energy is a legitimate topic in mainstream physics, but the idea that you can use it to do useful work is highly suspect, and in particular, claims that you can use vacuum energy to build a device which would violate the laws of thermodynamics (the term used by many cranks is "over-unity") is definitely cranky.---CH 23:59, 14 August 2006 (UTC)
Hmmm for a mathemetician with with no physics degrees that i have seen in your profile CH, you fling the word crank around alot. SEAS is run by a guy called tom valone I wouldnt call that a crank myself. And hal puthoff who while controverisal in some areas is a well acknowledged expert in vacuum energy [he hosted the NASA talks on alternative energy sources in 2001] agrees with many of these ideas. Just because you dont like his ideas doesnt make him a crank. Furthermore if you look at vacuum energy on this site even it is a huge resevoir of energy, so much that it should be bending time and space. That sounds like energy that can be put to work to me so this fact is not highly suspect, if it were NASA , british aerospace project greenglow, the calphysics institute, the institute for advanced studies in austin and a number of other institutes that are looking into what is not-known [and not highly suspect as you put it] is wether or not we can work with this energy or not with the tools we have at this moment in time. You cannot dismiss this fact. Dont get me wrong i do not beleive in free energy I only beleive that with the right tools we can make the vacuum energy do certain things, perhaps a novel system of propulsion by causeing the waves to effect, or changing them into negative energy like in the casimir effect, but not free energy. Also in closeing attacking the people of these websites is a logical fallicy, you are not disproving the argument only attacking the people. I will not say anything further exept that firstly the statement above is biased, secondly the person posting has no physics qualifications. Commenter
Birthday
In honor of my birthday (august 14th) I will ask a trivia question and review anyones article of choice if they get it correct. What is the probability that someone shares the same birthday as me if I am in a room with 22 other people? -Ravedave 02:15, 14 August 2006 (UTC)
- --Bmk 02:34, 14 August 2006 (UTC)
- yup thats it. Birthday Paradox. Which article Do you want reviewed? -Ravedave 02:38, 14 August 2006 (UTC)
- The way you've phrased it, 100% (certainly someone somewhere shares your birthday, whether you're in a room with 22 people, or five people, or alone on the top of the Eiffel Tower). But what you probably meant (what is the likelihood that at least one of 22 randomly chosen people will be born on a given day, in this case 14 August) would give an answer more like 6%. (The probability that any one person was born on a certain date (other than 29 February) is about 1/365 or more precisely 4/1461; they are independent events so they are added, so the probability is 88/1461 = 6%). Note that what you have proposed is not the birthday paradox, which asks for the probability of two of 23 people sharing a birthday, rather than specifying the date in advance. Happy Birthday. - Nunh-huh 02:39, 14 August 2006 (UTC)
- I relized that shortly after I posted it, however Birthday paradox does have the equasion dmk provided. -Ravedave 02:41, 14 August 2006 (UTC)
- And if you prefer digits...0.058571325264343345847099029333104. But I like Nunh-huh's 100% answer. --Bmk 02:46, 14 August 2006 (UTC)
- And happy birthday by the way. --Bmk 02:47, 14 August 2006 (UTC)
Now for a harder question: What is the probability it will be your birthday on any given day, if you attend a restaurant that gives away free birthday meals on that day (one that doesn't check ID) ? :-) StuRat 08:35, 14 August 2006 (UTC)
I'd say that won't be a constant, it will be a function of how often you visit the restaurant and how good the waiters are at remembering your face.1/365, because we're all scrupulously honest round here, right? ;-) -- AJR | Talk 12:46, 14 August 2006 (UTC)
- Bmk would probably prefer you said 1/365.2425. JackofOz 03:25, 15 August 2006 (UTC)
- Unless you're born on February 30. Then it's 1/1461... TERdON 08:34, 22 August 2006 (UTC)
- I think you mean Feb 29th. Our calendar never has a Feb 30. StuRat 06:46, 23 August 2006 (UTC)
- No, TERdON couldn't have meant 29 Feb. That date is already included in my 365.2425 calculation. Maybe he/she was just overcompensating for the loss of Pluto as a planet. :--) JackofOz 02:18, 25 August 2006 (UTC)
- I think you mean Feb 29th. Our calendar never has a Feb 30. StuRat 06:46, 23 August 2006 (UTC)
Insect identification
I found this insect which had apparently crawled out of my lawn onto the side of the curb and emerged from its chrysalis. After a few hours it flew away. Anyone know what it is? Thanks, --Bmk 02:21, 14 August 2006 (UTC)
- Some sort of Cicada apparently. Pretty interesting bugs. -Ravedave 02:29, 14 August 2006 (UTC)
- Thanks! I think that's the one! The picture on the cicada page was great. Extra points to anyone who can tell me what species this one is. It was seen in upstate NY, USA. --Bmk 02:58, 14 August 2006 (UTC)
- I looks like the one in the template to me which is of the genus Tibicen. I am guessing the one in your picture has light color becuase it hasnt matured. -Ravedave 04:21, 14 August 2006 (UTC)
- Thanks! I think that's the one! The picture on the cicada page was great. Extra points to anyone who can tell me what species this one is. It was seen in upstate NY, USA. --Bmk 02:58, 14 August 2006 (UTC)
- Compare this picture. --LambiamTalk 06:26, 14 August 2006 (UTC)
- Check out http://www.boingboing.net/2006/07/24/online_bug_identific.html for bug ID services. --Kjoonlee 10:21, 14 August 2006 (UTC)
- Tibicen it appears to be! Extra points all around. Thanks folks --bmk
- Check out http://www.boingboing.net/2006/07/24/online_bug_identific.html for bug ID services. --Kjoonlee 10:21, 14 August 2006 (UTC)
- As a side, somewhat irrelevant note, cicadas are what makes the loud, constant buzzing noise in many forest areas. In the Florida (where I live) wilderness it is easily identified if cicadas are in proximity (which they mostly are) and an appropriate nickname for their sound would be the white noise of the wilderness. Not many people I know actually know where this sound comes from, but if they read this now they know. Also, when I traveled to Costa Rica I found gargantuan cicadas that where nearly half a foot long. Pretty amazing, huh?--Porsche997SBS 20:24, 26 August 2006 (UTC)
non-chlorine bleach
Does it clean as effectively as chlorine bleach?
- Depends on what you're cleaning. I've never tried laundry, but fo whackin' out a person, no, the chlorine bleach works much better. — [Mac Davis] (talk)
- What do you do when your clothes start to smell? freshofftheufoΓΛĿЌ 11:14, 14 August 2006 (UTC)
- Stop using the stuff. DirkvdM 12:06, 14 August 2006 (UTC)
Reasons for car batteries going flat?
Hi
The battery in my car keeps going flat if i don't use it for a couple of days. Yet I've had the battery tested and they say there is nothing wrong with it. Could there be another reason?
- Probably your Alternator. Unless you are leaving your lights on. :) -Ravedave 04:15, 14 August 2006 (UTC)
- I should probably explain more. Your Alternator is what charges your battery when you are driving. So if its not chanrging your battery then it will go dead from beign used, but not charged. Also I have heard of stuff like hood lights staying on. -Ravedave 04:24, 14 August 2006 (UTC)
- If it is the alternator, and you have full gauges, the battery voltage will read a bit low. Look for that. StuRat 08:29, 14 August 2006 (UTC)
- Also, you could have an intermittent short circuit. For example, I had an 83 Trans Am which had an intermittent short in the passenger power door lock, which would eventually drain the battery. StuRat 08:26, 14 August 2006 (UTC)
- Is it winter where you are? Old car batteries tend to go flat if just left in the cold.
- Actually, batteries last longer in the cold. However, if they do go completely dead, they can freeze and split open, and thus be destroyed, by the cold. Also, it takes more juice to start a cold car, due to the sluggish cold oil, so a poorly charged battery will become more apparent in cold weather. StuRat 19:43, 14 August 2006 (UTC)
- Make sure you didn't put it in backwards! I always do that with my batteries. freshofftheufoΓΛĿЌ 11:13, 14 August 2006 (UTC)
- and if you've recently put in car electronics, you might have stuffed the wiring up so it draws current even when the ignition is off. it happens. Xcomradex 12:01, 14 August 2006 (UTC)
- There have been cases where the car's key fob receiver gets repeatedly activated, either by an external radio source (case study here) or by the fob itself being left overnight near the car (can't find a ref. for this, but read it a few days ago). This keeps the car's electrical systems continually awake and quickly drains the battery. --Heron 17:34, 14 August 2006 (UTC)
Sometimes car batteries just get old and need replacing! BenC7 02:16, 15 August 2006 (UTC)
As a person who has delt with bad car batteries (and bad cars) more times than I would like to admit, there are MANY reasons your battery might go bad. A bad alternator is the most likely cause, but also there are cells inside a batter that hold about 3/4 H2SO4 and 1/4 water. If the water evaporates, the battery efficiency is severely compromised. You can rememedy this by pouring a small amount of distilled water into the cells (NOT TAP WATER, this will cause a violent reaction that will spew acid on you) of a completely cold battery. Also, sometimes the terminals become corroded, which will cause bad connections between the power cables and the terminals; a solution of 1/2 baking soda and 1/2 water will take that corrosion right off in most cases. Frequent jumping and subsuquent light driving also ruins batteries because they cannot retain a good change, and then you have to jump them again...a cycle of pain. Sometimes batties just wear out...for a good one, 5-7 years or more, a cheap one, about 2 years. Hope that helps. --69.138.61.168 03:45, 15 August 2006 (UTC)
There is a rectifier in the alternator which converts the AC current to DC, if this is defective, the alternator will run AC current through the battery which will ruin it.
Check the glove box light and the trunk light. Make sure they are not staying on.
Wouldn't adding any water to concentrated H2SO4 cause a highly exothermic reaction (generates heat) that could splash acid on you? --Shanedidona 13:00, 23 August 2006 (UTC)
Chronic cough
My 6 years old daughter has chronic cough for more than one month. (Her cough starts when she goes to bed, during night and before she wakes up.)First it started with having caught cold and treated with antibiotic but her cough continued. When she was only 5 months years old, she was hospitalized by diagnosis of "Whooping cough" for 2 months. Now is there any relation between her chronic cough and this childhood disease? Is it a symptom of other disease or as her doctor says it could be an allergy?
- As usual, you might get better answers by paying a person with years of expertise, accountability, and far more information about your daughter, rather than anonymouse volunteers with unknown qualifications whom you cannot hold responsible. You don't specify some important details, but let's assume you are a middle class American mother and you daughter is basically healthy and growing well with no serious disease since pertussis in infancy. Some of the likely possibilities:
- She hasn't finished recovering from her viral respiratory infection
- She has an asthmatic cough from an environmental trigger (outdoor or indoor source)
- She has an asthmatic cough from a persistent sinusitis
- She has a habit cough (this is the typical age) or a psychogenic cough
There are many uncommon possibilities
- A foreign body in a bronchus
- Persistent gastroesophageal reflux
- Tuberculosis or rarer lung infections
- Tic or other neurologic cause
- Cystic fibrosis
- Hypersensitivity pneumonitis (e.g., histoplasmosis, or your local favorite)
- A vascular malformation in the chest
- Several types of immunodeficiency
There are many more rarer possibilities that you don't even want to know about. If she definitely had pertussis in infancy it is unlikely to recur. How certain was that diagnosis? Despite immunization?
If it isn't gone in a another couple of weeks, go see someone more knowledgeable and responsible than we are. alteripse 11:44, 14 August 2006 (UTC)
- If she's had a chronic cough for more than a month, the time to see the pediatrician is NOW. StuRat 21:16, 14 August 2006 (UTC)
- Another possibility, especially since you said this only happens when she lies down to sleep, is acid reflux disease. This means that the valve at the top of the stomach fails to prevent acid from entering the esophagus. During the day, gravity performs this function, but not when you lie down. StuRat 21:22, 14 August 2006 (UTC)
- Oops, I see that was already listed, under the name gastroesophageal reflux. StuRat 21:24, 14 August 2006 (UTC)
- Is her bed next to an outside wall? That's often the coldest part of the house, and I've sometimes had persistent nocturnal coughing for that reason. —Tamfang 07:12, 15 August 2006 (UTC)
Formula for calculating the Heating Load in KW of Convectional oven
Dear sir,
I am intrested to know that how to know the heating load in KW of convectional Heating oven if I know the Volume of Oven in Cumbic Meter and Weight of Material which has been put inside the oven and set temperature upto what time. I am also intrested to know, How Much Initial heating time effect the Heating load.
As I know the Heating Load is depend upon Set Temperature, Volume of Heating oven, Materail in side the Oven, Air Inside the oven, Thickness of Insulation, Heating up time, Ambient temperature. I am really intrested to know the optimum formula for calculating the heating load of conveyorised and batch oven.
Biggest cells, and hen's eggs?
How big is the biggest cell (animal, plant, or fungus) please? I remember as a schoolboy wondering about unfertilized hen's eggs. Now while it is extremely unlikely they are just one large cell, just how many cells do they have in them?
- The largest known cell is actually the Ostrich Egg, I'm pretty amazed by that as well. PvT 10:46, 14 August 2006 (UTC)
- Contrary to popular belief, and to thier names, ostrich and hen's eggs (and any other poultry eggs) are not single cells. In the yolk of the egg, there is just one single cell - that of the embryo, which divides and grows during the incubation of the egg. As for your original question, I'd say that the biggest cells would be those of some single celled organisms, such as algaes. Martinp23 12:14, 14 August 2006 (UTC)
- I would have to say that some plant cells are large enough to actually see with a nude eye. I recall those are the largest known. — [Mac Davis] (talk)
- Caulerpa (a green alga) are pretty big. Each plant is a single cell (albeit with multiple nuclei) and the whole organism can grow to be about 3 meters long. TenOfAllTrades(talk) 15:13, 14 August 2006 (UTC)
It says in the Ostrich entry that the eggs are the world's largest single cells. If that is not true, then the entry needs to be changed. I'm rather sceptical as a cell that size would have tremendous problems with respiration. But if it is the case, what do the yolk and egg correspond to? If there is just one little cell in an unfertilized egg, where is it? And the sac (correct spelling I think) containing the yolk, or the membrain inside the shell, how were those made? It could have been made of specialized cells. Cells<-->eggs are still a mystery. If an Ostrich egg truely is a cell then it must be bigger in volume than the algae cell, even if its 3m long.
- I thought that in an unfertilised bird's egg the yolk is one great big haploid cell, with no cell membrane between the chromosome-containing non-yolky clear cytoplasm on one side, and the rest of the yolk - a telolecithal cell which will undergo meroblastic cleavage. Is that right? Strange how difficult it is to get real hard facts on this. A fertilised egg, by the time it is laid, is multicellular (already 60000 cells), and the blastodermal cells are separated from the yolk that has no nucleus, so that does not count as a single cell. How long can a giraffe's spinal nerves be (bonus: has only one nucleus), and how big are the the neurons of giant squids? What would be the size of the (multinucleate) muscle cells of an elephant or a whale? --Seejyb 23:36, 14 August 2006 (UTC)
Electrical Engineering
My question is a very ODD one .
The question is : -
Out of AC and DC voltages which poses a repulsive shock and which an attractive shock ?
Please reply soon .
- I'm not sure what you mean by a "repulsive" or "attractive" shock. They both are pretty unpleasant if the voltage is high enough, so I guess they're both pretty repulsive to me :). But seriously, I think what you may be referring to is the way that strong electric currents cause muscles to contract, resulting in a person being unable to release the source of the voltage (the actual reason is that flexors are usually stronger than extensors, so when they both contract, the flexors win). Other than that, I think you should read our article on electricity to get the basics down. --Bmk 12:54, 14 August 2006 (UTC)
I think I know what the confusion is here. In modern electric fences, they frequently turn the voltage on and off every second or so. This allows people who get zapped by them to let go, and thus survive. This is unrelated to A/C versus D/C, however. StuRat 21:10, 14 August 2006 (UTC)
- Can you be more specific with your question? --Proficient 21:36, 17 August 2006 (UTC)
- Neither is very attractive -- in fact both are quite shocking and repulsive! (sorry!)--Light current 05:44, 19 August 2006 (UTC)
Why the male Warbler builds unused nests?
Protonotaria citrea - (Boddaert, 1783) Prothonotary Warbler Unique Identifier: ELEMENT_GLOBAL.2.100372 Element Code: ABPBX07010
I have read :
The Prothonotary Warbler is a small songbird of the New World warbler family. It breeds in hardwood swamps in southern Canada and the eastern United States, nesting in a cavity. The male often builds several incomplete unused nests in his territory; the female builds the real nest. It winters in the West Indies, Central America and northern South America. This bird was named after officials in the Roman Catholic Church known as the protonotarii, who wore golden robes.
Most activities in the animal kingdom have a biological advantage, I was wondering if the male bird does this activity, as a method of fooling predators. ie, the predator will see the false nest and attempt to steal eggs from that nest....
Any information about this would be much appreciated.
- It is an interesting division of labour. The male typically selects several potential nesting sites in advance, and "illustrates" their suitability by building a dummy nest, using moss. It's a bit like a real-estate agent dressing up a place for viewers. When a female arrives, the male shows her around, and if she is sufficiently impressed by one of these sites, she'll turn it into a real nest. As a male you always wonder: "What does woman want?" By selecting several sites, the male increases the likelihood that the female will like one of them. --LambiamTalk 01:10, 15 August 2006 (UTC)
This piece of 'equipment'?
I have been challenged to find out the name of this piece of equipment, I can only guess it is used somewhere in science but having looked through various lists on here of science equipment and clicking on the ones that I hadn't heard of hasn't actually got me anywhere. The piece of equipment is linked below.
http://img136.imageshack.us/my.php?image=6iu2.jpg
I'm guessing the image is probably somewhere on wiki. Thanks. ~~
Warning. The link opens a popup that crashes Konqueror. DirkvdM 12:15, 14 August 2006 (UTC)
- Looks like an empty Stevenson screen. DirkvdM 12:15, 14 August 2006 (UTC)
Thanks, I found the exact image on google images when I searched it so I guess that you're right. Sorry if it crashes Konqueror, I'd only tried it on Firefox. ~~
- Crashes Konqueror 3.2 on Mac OS X Tiger as well. O_o --M1ss1ontomars2k4 (T | C | @) 23:05, 23 August 2006 (UTC)
gold - precious metal
what makes gold so precious? what quality does it have that is of so much value?
- 1) It is scarce. That alone makes people want it. Which makes it more scarce, etc. Which is a bloody shame, because this jewellery-nonsense forces up the prices also for
- 2) practical implementations. It is one of a sel;ct group of chemicals that are not very reactive. In plain English, it doesn't rust. For that reason it is used for electrical connections because they are especially prone to rust, which reduces their conductivity, their very reason for existence. DirkvdM 12:24, 14 August 2006 (UTC)
- Practicality aside, if you've ever held 99.9% pure gold in the sunlight, it is just so incredibly pretty! I think that's the real reason :) --Bmk 12:56, 14 August 2006 (UTC)
- Because it's so non-reactive, it's one of a very few elements that are commonly found in the pure form (nuggets). This meant that it was one of the first elements to be discovered in antiquity, so people started figuring out how to make pretty things out of gold long before they did so with other things. Result: several millennia of accumlated cultural mystique. --Pyroclastic 19:10, 14 August 2006 (UTC)
Gold just has lots of practical applications in industry. For the same reason copper is actually rather valuable — a couple bucks a pound. --Cyde Weys 17:03, 14 August 2006 (UTC)
- Gold is quite ductile (soft), which makes it easy to work with. It's also highly electrically conductive, which makes it good for wiring (except it costs too much for most wiring), and, as previously noted, it doesn't oxidize, like iron (to form rust), silver (to form tarnish), copper (to form that nasty green stuff), or aluminum (to form white spots). If it was plentiful enough (and thus cheap), we might even make car body panels out of it. StuRat 21:04, 14 August 2006 (UTC)
- Copper is so valuable that it's being stolen frequently. Recently, a nearby school had ten classrooms flooded because thieves broke in to steal the copper pipes. User:Zoe|(talk) 02:19, 15 August 2006 (UTC)
- copper is also running out, hence the price hike. Xcomradex 07:59, 15 August 2006 (UTC)
- I thought i would throw in that Silver is a better room temperature conductor than gold, and that gold car panels would be impractically soft and heavy, high grade aluminum would be a more feasible corrosion-resistant choice. --66.195.232.121 13:37, 15 August 2006 (UTC)
- Silver wouldn't be as good as gold for electrical use, because it tarnishes, and the silver oxide would prevent electricity from flowing across electrical contacts. Gold isn't any softer than the plastic body panels used on many cars. And aluminum gets those ugly white spots of aluminum oxide. StuRat 18:47, 15 August 2006 (UTC)
- Technically silver tarnish is really Silver Sulfide, as it reacts slowly with Hydrogen Sulfide found in trace amounts in the air. Over time the black tarnish builds up.
- I never thought about copper being valuable, but then you must think about the prices of some higher end heat sinks to see its value. --Proficient 21:41, 17 August 2006 (UTC)
Human Decomposition
How long do you have to wait until all that's left of a corpse is a skeleton? --Burbster 12:09, 14 August 2006 (UTC)
- Longer than you'll live if it's in a bog. So if ou don't slide into the bog yourself, you'd decompose before the other body. More in general, this depends to a large degree on how much oxygen the body is exposed to. And the temperature also makes a big differnce. This was asked before, but I can't find the thread. DirkvdM 12:29, 14 August 2006 (UTC)
- This depends enormously on its environment. See decomposition. --Shantavira 12:30, 14 August 2006 (UTC)
- If the environment is a vat of strong acid, a few seconds. If the environment is a inter-galactic void, never. StuRat 20:59, 14 August 2006 (UTC)
- Depends on the molarity of the strong acid. It might take considerably longer than a few seconds. --Amanaplanacanalpanama 21:41, 16 August 2006 (UTC)
Okay, let's say instead for three different environments: Out in the open air at moderate humditiy, in a shallow grave and in a coffin buried deep underground. --Burbster 23:32, 16 August 2006 (UTC)
- You're asking purely for academic reasons? Rentwa 20:11, 26 August 2006 (UTC)
The 'save' button is teasing me
Because three questions up Konqueror crashed, I switched to Mozilla and now I notice the strange effect that when I hit the 'save page' button, the screen moves up a bit. Only when I hit it a second time does it work. Is the button teasing me? DirkvdM 12:31, 14 August 2006 (UTC)
- I've had the same thing for a while now, on my Linux machine. --Zeizmic 12:36, 14 August 2006 (UTC)
- Because the questioner is using Konqueror, I assume he is using KDE. I use Firefox in KDE and have no issues with the save button. --Kainaw (talk) 16:59, 14 August 2006 (UTC)
I have issues like this occasionally with Firefox on Windows. My only guess is that, for whatever reason, when you try to click the button it instantaneously re-renders the page such that the new ___location of the save button is no longer under the mouse pointer, and thus, it doesn't get clicked. This might be JavaScript-related. --Cyde Weys 17:02, 14 August 2006 (UTC)
- This occasionally happens with all my Windows applications. Clicking on the scroll bar clears it for me.--Shantavira 17:31, 14 August 2006 (UTC)
- I am indeed using KDE (under Suse). And it might indeed have something to do with Javascript. Between the edit frame and the options above it, there is some space. When I hit the save button, this space disappears. It might indeed re-render then. But when I hit the top of the save button, it doesn't move up enough and there is no problem (the button works). I don't have Javascript enabled for Konqueror, so that may be it. Nothing to do with the OS, the DE or the browser. DirkvdM 17:50, 14 August 2006 (UTC)
- This actually has to do with your Wikipedia preferences. If you go to your preferences and the Editing tab, at the very bottom is a option saying "Prompt me when entering a blank edit summary". If you checked it, then if you enter nothing or enter /*(text)*/ in the edit summary and click save, at the top you will get a message telling you: "You have not provided an edit summary. If you click Save again, your edit will be saved without one." Only if you click save again, it will save. --Yanwen 18:14, 14 August 2006 (UTC)
- No, that's not it - I don't have that checked. It is Javascript. I just disabled it and the problem is gone. DirkvdM 09:05, 15 August 2006 (UTC)
If mountains have effect on earth Consistency and stabilizing?
the earth has move (in orbit) and shake. if mountain effect it and other things similar these? —The preceding unsigned comment was added by 194.225.166.13 (talk • contribs) .
- I'm not exactly sure what you're asking, but let me point out a few things that may be relevant. The overall shape of the Earth is practically a perfect sphere: the equatorial bulge is small and Mount Everest is even smaller. I don't see how mountains could have any "stabilizing" effect on earthquakes. In fact, the same tectonic activity that produced the mountains could also produce earthquakes, so I'd say earthquakes are more likely to occur in mountainous regions, not less. —Keenan Pepper 16:06, 14 August 2006 (UTC)
- I think the question is if mountains cause earthquakes. The answer would then be that they are both caused by tectonic plate movement and volcanic activity.
- The plates of the Earth's crust move about (extremely slowly) and collide with each other, pushing up mountains (like the Himalaya). This causes friction, which also causes earthquakes.
- Below that crust is lava, which sometimes breaks through and causes volcanoes, another type of mountain (like the ones in Indonesia). And this also causes earthquakes.
- So mountains don't really cause earthquakes, but the two have a common cause, so that's why earthquakes occur in mountainous areas. If your English isn't good enough to read these articles, you might want to have a look at the Simple English Wikipedia. It is not quite as extensive as the 'normal' Wikipedia, though. DirkvdM 18:13, 14 August 2006 (UTC)
- Although I'm not quite sure what the question is, I suspect it may be related to the recent news item that the 2004 Indian Ocean earthquake had perceptibly altered GPS satellite orbits. --LambiamTalk 00:52, 15 August 2006 (UTC)
I think the question-asker may be referring (knowingly or unknowingly) to Milankovitch cycles rather than earthquakes. Do mountains have an effect on orbital parameters? might be what is being asked, I think - much like if you stick a blob of something to a ball it will affect how it spins. With regards to the Earth, the answer is no. If the earth was scaled down to 7 or 8 centimetres across, it would be smoother than a billiard ball. Mountains are not large enough with respect to the Earth to make any difference to its orbit, spin, precession, etc. BenC7 02:32, 15 August 2006 (UTC)
- He could also be asking about isostasy. Titoxd(?!?) 07:24, 17 August 2006 (UTC)
Instrument
http://img136.imageshack.us/my.php?image=6iu2.jpg
Could someone kindly tell me what this scientific instrument is...it looks like a beehive but i`m relatively sure it`s not.
- That is a weather station, where anyone interested in measuring the weather puts instruments such as barometers and thermometers, where they are subjectedto the atmosphere but protected from the elements. Martinp23 14:40, 14 August 2006 (UTC)
- Are you the same person? We just had this question a few hours ago. The answer is Stevenson screen. — [Mac Davis] (talk)
artificial insemination
Can all animals be inseminated artificially?
- Yes. Its really the phallus that is artificial, not the semen. I guess the insemination is artificial. Anyway, it doesn't matter if there was copulation involved, the sperm just has to get to the egg. — [Mac Davis] (talk)
- Technically, some animals, such as Cnemidophorus lizards, cannot be artificially inseminated, because they don't reproduce sexually. See Parthenogenesis. —Keenan Pepper 16:09, 14 August 2006 (UTC)
- Well, you need more than the sperm and the egg. You also need a womb (if you want a baby to come out of it, that is). So you indeed have to enter something in a female, be it a fertilised egg, as it is done with humans, or with a functional dildo, so to say. I can imagine that with some animals that would be problematic, like very small animals (without killing them, which would defeat the purpose). Or with very big ones. Try inseminating a whale (a sperm whale of course :) ). DirkvdM 18:26, 14 August 2006 (UTC)
- It might be very difficult for microscopic animals. I wonder if anyone does this for any reason. Also remember that creatures such as sponges and corals are animals. Maybe they could be "artifically inseminated", but it would be much different that the process for a horse or a pig. ike9898 19:49, 14 August 2006 (UTC)
- There may be a technical problem for Diplozoon paradoxum. For an illustration of the fused animals, see da:Dobbeltdyr (Diplozoon paradoxum) or the middle of the bottom line of the image at Flatworm. --LambiamTalk 00:35, 15 August 2006 (UTC)
- Many animals fertilize externally, in which situation this question is a non sequitur. --Ginkgo100 talk · contribs · e@ 03:46, 15 August 2006 (UTC)
Maximum velocity of a sailing ship
Can a ship powered only by sail exceed the wind velocity? If so, what is the maximum speed it can reach relative to the wind velocity? --Cyde Weys 16:59, 14 August 2006 (UTC)
- If the water current exceeds the wind velocity then the ship can lower its sails and go as fast as the water current. -- C. S. Joiner (talk) 17:25, 14 August 2006 (UTC)
- And a more serious answer can be found here: "the motion of the boat creates its own apparent wind, which combines the windspeed vector and the hull speed vector. Sailing into the wind, this can quickly add up to apparent winds of far greater than the true windspeed" -- C. S. Joiner (talk) 17:37, 14 August 2006 (UTC)
- Per Csjoiner, yes—modern racing hulls are efficient enough to exceed the wind speed when on a broad or beam reach. (Most sail boats are fastest on a beam reach, though may not be able to exceed the wind's speed.) Ice boats, because they travel on a very low friction surface, can usually easily exceed the wind's speed when reaching. TenOfAllTrades(talk) 17:44, 14 August 2006 (UTC)
- The reason for this is that the boat is (at least when on a beam reach or closer to the wind) not mainly powered by the direct force of the wind on the sail. It is driven by the bernoulli effect of the wind blowing across the wing-like shape of the filled sail, and thus is not limited by the velocity of the wind. --198.125.178.207 18:25, 14 August 2006 (UTC)
- Hold on. Sailing into the wind? That won't get you anywhere, or do I get the English sailing terms wrong? (If not, the article needs correcting.) But even sailing upwind (at an angle of up to about 45° to the wind) isn't very fast - it just feels very fast. Sailing downwind is a lot faster and quieter. But that way you just get pushed by the wind and you miss out on the wing-effect. Indeed, broad or beam reach (getting the wind from the side) is fastest. That way you can indeed exceed the speed of the wind. Which sounds counterintuitive, but so does the ability to sail upwind (close hauled). Both are possible thanks to the wing-effect.
- By the way, if things go just right, the bough can be lifted on to of the bough wave. This has happened to me once (in a Valk or 'falcon' - I thought we had an article on that) and it's a wonderful feeling, like you're flying. What is this called and is this an indication one is exceeding the wind speed?
- About the Points of sail article, I disagree with calling running downwind a 'don't go zone'. Getting 'gull wing' right is one of the nicer moments of sailing. DirkvdM 18:45, 14 August 2006 (UTC)
- "Sailing into the wind" is indeed a not uncommon (but potentially confusing) way of expressing "sailing upwind". You also hear "sailing against the wind" (which makes me wonder who was the winner), possibly influenced by German gegen den Wind segeln or similar expressions in other Germanic languages. --LambiamTalk 00:21, 15 August 2006 (UTC)
Sodium azide interferes with SDS-PAGE?
If you have experience with SDS-PAGE, have you ever had a problem with having too much sodium azide in your samples? Would you suspect this would interfere at high concentrations? ike9898 19:10, 14 August 2006 (UTC)
- What is the nature of your problem, and what concentration of azide are you using? I can say, however, that I regularly use azide in my peptide samples to prevent bacterial contamination, and I've never had any problem with them (none, at least, that I traced to the presence of azide). – ClockworkSoul 21:33, 14 August 2006 (UTC)
Formatting an External Harddrive
I have an external USB hard drive. It is currently in NTFS, but I want to format it in FAT32 so that I can use it with my Linux dual boot. Windows XP doesn't let you format it into anything but NTFS and I'm a Linux noob running Ubuntu. I tried GParted, but it doesn't seem to be able to manage externals. Any help? --Russoc4 20:18, 14 August 2006 (UTC)
- This is probably a better question for the Computing Reference Desk -- C. S. Joiner (talk) 20:23, 14 August 2006 (UTC)
- Oh dear. I didn't realize they made one! Thanks for your help. --Russoc4 20:25, 14 August 2006 (UTC)
- Give it to one of your friends that runs a Mac, it only takes a few clicks. — [Mac Davis] (talk)
- In the command prompt 'format [drive letter]: /FS:FAT32'
P = I*V
And now for a completly unrelated question to the one above...
I know that Power in Watts = Current * Voltage. I know that current is the flow of electrons and voltage is the potential energy to push the electrons, , but I'm not sure what that means in practice. Lets say you have a 100W lightbulb. Is there any different in powering it with 20 amps and 5 volts compared to 2 amps and 50 volts? How about for a DC motor? What role do each current and voltage play when powering a motor? I've been wondering about this for a while, but I keep forgetting to ask it.--Russoc4 20:25, 14 August 2006 (UTC)
- One quick response--while 20A*5V = 2A*50V in power output, they would work differently based on the limitations of real world material. 20 amps is a lot to send through wires.
- It may also help, when thinking about this topic, to remember V = I*R, therefore, P = I2*R, which might make more intuitive sense when thinking about the "roles" of current-voltage-resistance in motor power. -- Scientizzle 21:00, 14 August 2006 (UTC)
- One difference between powering a 100 W light bulb with 5 V 20 A or 50 V 2 A is that you would have to use different bulbs. Another difference is that the low voltage case would need power supply wires that have more copper in them, but could get away with less insulation. Since insulation is generally cheaper than copper, higher voltages are generally preferred. In the case of electric motors, the windings for a high voltage motor will have comparatively many turns of thin wire, while the low voltage motor will have fewer turns of thick wire. --Gerry Ashton 23:13, 14 August 2006 (UTC)
- Nowadays bulbs may say "100W" while they have much lower wattage but equivalent luminosity, an unfortunate development. Let's assume it is a "true" 100W bulb, which has been designed for use at 120V. Then the current going through will be 100W/120V = 0.833A. It's resistance, using Ohm's Law, is then 120V/0.833A = 144Ω. The latter is an actual physical characteristic of the lamp, independent of the voltage applied. If instead of 120V we apply 60V, we get a current of 60V/144Ω = 0.417A, and a power of 0.417A × 60V = 25W, only a quarter of what it says on the bulb. Likewise, if we apply 240V, we get a power consumption of 400W in the split second before the filament melts. The point is that the wattage listed is not an invariant physical characteristic, but only applies within the design parameters. --LambiamTalk 23:48, 14 August 2006 (UTC)
- In many real materials, resistance is a function of temperature. So the 144Ω figure may only apply at the temperature which the filament reaches in operation at that voltage. So it's even more design-specific than you suggest. In general, a bulb will have an output (e.g., blackbody radiation) and a resistance . At equilibrium, , or . Since output tends to increase very rapidly with temperature, even if we expect to find a balance. (In fact, resistance tends to increase with temperature due to increased disorder within the material.) Of course, even this is a simplification since in reality there will be temperature variations (and thus resistivity variations) within the wire and the current may create complex patterns that are harder to analyze. The important bit with respect to the initial question is that for most things as simple as light bulbs, once you pick the voltage the current is determined, so you can't just "go to" half the voltage and twice the current and "see what happens". Hope this helps. --Tardis 06:49, 15 August 2006 (UTC)
- Well, all these answers do help put it into perspective. thanks. --Russoc4 15:38, 15 August 2006 (UTC)
Don't fall into the trap of thinking that P=I*V is true for AC. It is strictly true only for DC. For AC, it is true only for a load which is purely resistive. A resistive load could be a heater or an incandescent light bulb. Any load which is reactive, containing net inductance or capacitance, will consume power less than I*V. High voltage power lines (such as 345 kv) are likely to be capacitive (combination of resistance and capacitance) and the current will lead the voltage. Residential loads, with motors and air conditioners, are likely to be inductive combination of resistance and inductance. In an inductive load the current waveform will lag behind the voltage waveform. The electric meter on your house bills for energy used in kilowatt hours; the reactive current is basically free. Commercial and industrial customers are billed if their power factor is too reactive. The reactive current is termed VARs for "volt-amps reactive" and the power company hates them, since they heat up transformers and distribution lines just like revenue-producing watts. They install capacitor banks to improve the power factor towards unity (neither inductive nor capacitative). Edison 16:51, 15 August 2006 (UTC)
G2B2... what does it mean?
Trying to figure out what G2B2 means in a medical context, as an adjective applied to a woman, or as a status associated with a woman. --MattShepherd 20:37, 14 August 2006 (UTC)
Perhaps if you provided the specific context in which you heard this term it would be easier for us to figure out what it means. Was it on a lab sheet? ...in a text book? Did you overhear it? Tuckerekcut 20:46, 14 August 2006 (UTC)
Asked in passing by a translator friend, who didn't give me much else to go on. I'll figure it out. --MattShepherd 20:55, 14 August 2006 (UTC)
- Did you mean G2P2? It is shorthand for an obstetrical history. "G" (for gravida) refers to the number of pregnancies. "P" (for para) refers to the number of live births. Some include an "A" or "SA" for abortions/miscarriages. G2P1 means 2 pregnancies, 1 delivery (and currently pregnant with the second). G1P2 means 1 pregnancy with a set of twins delivered. - Cybergoth 21:30, 14 August 2006 (UTC)
- It might refer to a GABA A receptor structure: a γ2 and a β2 subunit. --LambiamTalk 23:30, 14 August 2006 (UTC)
- The way you describe the circumstance in which the term is used would indicate the pregnancy related meaning. "G" does refer to the number of times the woman has fallen pregnant. As noted, the second letter is a capital "P", but these days a somewhat complicated four-digit "code" follows it. The first digit after the P indicates the number of full-term pregnancies (those that lasted > 37 weeks), the second, the number of pregnancies where a premature baby was born (20-37 weeks' pregnancy), the third, the number of pregnancies ending before 20 weeks (spontaneous or induced abortion), and the fourth indicates the number of children living at present. An example would be "G5 P3115", analysed as: G5 = times pregnant, P3xxx = 3 times full-term pregnancies, Px1xx = 1 premature delivery, Pxx1x = 1 miscarriage before 20 weeks, and Pxxx5 = 5 living children. Note that this does not indicate in what sort of combination(s) the 5 living children come from, all one can say is that out of 5 pregnancies, 4 lasted to a viable gestational age. They could all have been twin pregnancies, with three kids having died, one from prematurity, one poisoned by her husband, and one in battle. The coding does not allow for indicating twins, triplets, and such. Note also that if the first three numbers following the P add up to 1 less than the G, then it indicates that the woman is presently pregnant. --Seejyb 01:04, 15 August 2006 (UTC)
broken neon
Do broken neon tubes release a dangerous amount of mercury vapor? I was in a convenience that had a broken neon sign and I'm wondering if I should bother with going to the doctor. KeeganB
- According to neon sign, only some neon signs use mercury and it's a drop of it at that. Spread out to an entire convenience store, it's probably fine. AEuSoes1 21:05, 14 August 2006 (UTC)
- And since it is elemental mercury in the sign, instead of a vapor, you are in less danger of mercury poisoning than if it were methylmercury or similar. Hyenaste (tell) 23:43, 14 August 2006 (UTC)
Doesn't elemental mercury produce a poisonous vapor? Anyway, I forgot to point out that the duplicates of this sign produced blue light, which it caused by mercury. KeeganB
- I wouldn't worry to much about your mercury exposure. I myself have come into contact with a solution which contained a small amount of the mercury salt mercury(II)chloride without even knowing what it was till much later. As far as I know elemental mercury is actually quite safe compared to its salts. Seeing how very little is in the tube to begin with I wouldn't think that you have anything to worry about at all short term or long term. PvT 12:36, 15 August 2006 (UTC)
I don't have a scientific basis for questioning that mercury is every bit as deadly as its present reputation. The term "mad as a hatter" is supposed to refer to recognition centuries ago that exposure to mercury caused brain damage. But a few decades ago everyone in chemistry class got to roll some of it around in the palm of his hand and it felt really cool. It would also coat a penny and make it look like a dime. In the late 19th century, gold miners would make up snowball-like wads of gold ore and mercury with their bare hands to extract the precious metal. Electrical experimenters used it all the time for low resistance low friction contact points is circuits. Mr. Wizard on TV kid science shows used mercury many times this way, as for a "jumping spring." 19th century photographers used it to make Daguerrotypes. It was in fever thermometers, which many a child bit through and got mercury in the mouth. It is in the silver amalgam fillings which have been in the mouths of many millions of Americans for many decades. For these reasons, I have to feel a little skepticism about the deadly peril of the vapor from a drop of spilled mercury. Edison 17:05, 15 August 2006 (UTC)
- You're right on the first point, you don't have the "scientific basis" for understanding the difference between mercuric nitrate, dimethylmercury, methylmercury, and mercury the element. If I were to follow the reasoning you have just outlined, I would have to conclude that the toxicity of chlorine gas is a myth, after all, people consume sodium chloride all the time, and don't do anything other than raise their blood prease, therefore chlorine isn't really toxic, that's just media hype, bah, brain hurt.--71.247.125.144 03:05, 17 August 2006 (UTC)
Mercury is what is known as a heavy metal poison. What is dangerous about it is it bioaccumulates. This means any taken in to the body is not eliminated very quickly, so if you are exposed to it as a very young child most of it will still be in you when you are very old. Other poisons, like cyanide, will allow you to recover from a less than fatal dose as the poison will be eliminated after a time, a few days maybe. Poisons which bioaccumulate won't do that. Sicne Mercury is a liquid, it has a higher vapor pressure than solids so you can inhale enough to be significant. The amount in a neon tube is not very much, you would have to hang around the convenience store a long time (weeks) with a neon tube breaking nearly every day to have a chance of having problems.
Mammals and body temperature
Could someone explain why, say, my cat has a different body temperature than myself, even though we share a great deal of temperature-sensitive biochemistry? Peter Grey 23:29, 14 August 2006 (UTC)
Seriously, doesn't it seem odd that mammals have so many genes in common, and these genes govern chemical reactions highly sensitive to temperature, and yet different species have different normal body temperatures? Peter Grey 18:14, 19 August 2006 (UTC)
digression:individual temperature
- Try reading body temperature, particularly the section on variations in body temperature between different mammals. That should give you a start. :-) Anchoress 00:36, 15 August 2006 (UTC)
- Thermoregulation discusses temperature variation for an individual, not variations across species. Peter Grey 02:22, 15 August 2006 (UTC)
On a related subject, I remember seeing a chart purporting to show how you can read the temperature in a room from the posture of a resting cat. Wish I could find that again! —Tamfang 06:53, 15 August 2006 (UTC)
- They also find the warmest and coolest ___location in the house. I once found my cat sleeping in the bathroom sink. I thought it's little walnut brain had blown a fuse until I realized the ceramic sink was connected to thick metal pipes filled with cool water, and probably stayed cool all day long. StuRat 07:41, 15 August 2006 (UTC)
Mushroom clouds
Was the Trinity test the first instance in which the iconic mushroom cloud seared its image into humanity's collective consciousness, or did scientists even before the first nuclear explosion have an idea of what the resultant cloud would look like? --Cyde Weys 23:34, 14 August 2006 (UTC)
- Read our article Mushroom cloud; it suggests that they should have known the answer if they asked the question. Probably they were smart enough to figure it out anyway without experimental evidence. I don't remember reading anywhere that they actually wondered or speculated about this aspect, although it appears unlikely to me that they wouldn't have. --LambiamTalk 00:03, 15 August 2006 (UTC)
- Note that much smaller conventional explosions also produce mushroom clouds, so people would have known about them long ago. I would even think, under the right circumstances, that a volcano could produce a mushroom cloud. StuRat 00:33, 15 August 2006 (UTC)
- Somebody lit a match near the Porta-potties after the chili bake off ? StuRat 07:34, 15 August 2006 (UTC)
- Image-google 'volcano "mushroom cloud"' for some nice examples. DirkvdM 09:15, 15 August 2006 (UTC)
- Before the Trinity explosion, they did a trial run with 100 tons of TNT to get an idea of what a large explosion would do, and how the radioactive fallout would behave. That explosion also generated a mushroom cloud. --Serie 22:46, 15 August 2006 (UTC)
Orphaned comment
I'm not sure where this belongs, because it was added to the Science Ref desk after this date had been transcluded:
Straight after exercise jump into icy water, it helps with the recovery process. Einstein's shadow 11:47, 17 August 2006 (UTC)
Straight after exercise jump into icy water, it helps with the recovery process. Einstein's shadow 11:47, 17 August 2006 (UTC)
August 15
the direction of the Earth's orbit
The Earth follows a path around the Sun. Given that the globe is spinning, how would one describe or calculate the direction of its orbit in terms of planetary coordinates?
Or, to put it another way: imagine an axis through the Earth which always points in the direction of the planet's orbit around the Sun. Would the points this axis describes on the surface of the Earth form a meaningful pattern, and how would it be described? --Halcatalyst 02:13, 15 August 2006 (UTC)
- I think I understand what you are asking. You would need to realize that the Earth's orbit isn't "pointing" in one direction, like a curved line with an arrow on the end. You need to think in terms of Vectors. One vector points in a straight line out into space, based on the direction the earth is going at that specific moment (inertia). The other vector points in a straight line towards the sun, representing the acceleration of the earth towards the sun (gravity). When you combine the effect of these two vectors, the earth follows a circular path around the sun. BenC7 02:45, 15 August 2006 (UTC)
- Yes. I'm interested in the vector of inertia, and the pattern it would trace on the Earth's surface over time. --Halcatalyst 02:57, 15 August 2006 (UTC)
- If we're talking about the velocity vector of the earth here, during a single rotation, it doesn't change significantly in the solar coordinate system, so as the earth rotates on it's 23.5 degree-tilt axis, it will trace out a circumference of the earth. Because the earth keeps its axial orientation (in the solar frame) over the course of a year, the circle will slowly rotate on the earth's surface (at the equinoxes it will trace along the equator, at the solstices, it will trace a "perpendicular" circumference), and the trace will wander around between the + and - 23.5 degrees latitude. Over a long time, it will travel through every point (approximately) between the latitudes +23.5 and -23.5 degrees. Actually, I don't know - does anyone know if the earth's rotation is in any kind of resonance with its orbit around the sun? If so, it will only have a limited "rosetta" pattern on the earth's surface, rather than hitting every point. --Bmk 03:24, 15 August 2006 (UTC)
- Good point, but the slowing of the rotation (from something like 22 hours in the dinosaur age?) implies that there is no resonance. So, yeah, the curve is space-filling. —Tamfang 06:48, 15 August 2006 (UTC)
- I guess so, unless the earth's orbit is slowing down to match? I don't know. --Bmk 16:08, 15 August 2006 (UTC)
- Good point, but the slowing of the rotation (from something like 22 hours in the dinosaur age?) implies that there is no resonance. So, yeah, the curve is space-filling. —Tamfang 06:48, 15 August 2006 (UTC)
- Since nothing is working on our orbit in the way that tidal friction works on our rotation, it is believed that the length of the year can be changing only if the gravitational constant is changing, as some theories suggest, but consensus says that's not happening either. —Tamfang 06:42, 16 August 2006 (UTC)
- Actually, according to general relativity, orbiting bodies give off gravitational radiation, which does slow the orbit. In GR, there are no stable orbits! Also, there is the effect of interplanetary gas dragging on the planet. Of course, both of these effects are extremely small, and they probably have a negligible effect, but nonetheless, they exist. --Bmk 17:44, 16 August 2006 (UTC)
- Thanks for a good discussion! --Halcatalyst 20:02, 17 August 2006 (UTC)
Warm vs cold blooded
Hi
My question is about energy use in cold blooded animals vs warm blooded animals. I have written;
"A lucky 70 kg snake might find a 15 kg pig to eat. This would provide it with enough energy for about three months of living, give or take. If you or I, on the other hand, ate 15 kg of bacon, this would sustain us for a bit more than a week."
Do these numbers seem reasonable? What numbers would you use?
Thanks very much for your help
Aaadddaaammm 03:18, 15 August 2006 (UTC)
- It sounds erroneous to me. The normal number is 2000 kcal/day, or of course 14000 per week. 15000 grams of bacon would then have to have less than one (dietary) calorie per gram... and as can be seen on most nutrition labels (at least in the US), protein has 4 and fat 9 calories/gram. Maybe if, somehow, 80%-90% of bacon was indigestible, this would work out; otherwise it's off by quite a bit. --Tardis 06:53, 15 August 2006 (UTC)
- I don't know about you, but if I ate 15 kg of bacon I would feel very, very sick and would wish that I would die. --LambiamTalk 09:11, 15 August 2006 (UTC)
- Yeah, we can't eat 15 kg of meat at once. Maybe 1 kg a day would be quite reasonable sustinance. - Rainwarrior 19:20, 17 August 2006 (UTC)
Brain in computer
Is it possible to use a brain as a computer hardware? If yes, is it currently researched?
- In principle any nontrivial information-processing device can emulate any other (given enough storage), but the structure of an organic brain is so different from that of a digital computer that it's hard to imagine circumstances in which anyone but an extremely mad scientist would ever try it. —Tamfang 06:46, 15 August 2006 (UTC)
- I find the reverse to be much more interesting, a human brain that could instantly access info from a computer. For example, think about what could be accomplished by combining the creativity of the human brain with all the misinformation in Wikipedia ! StuRat 07:28, 15 August 2006 (UTC)
- That's not a terrible idea, but it wouldn't really be all that interesting, you wouldn't really be connected, you'd just be using your mind to do the equivalent of clicking a mouse, I imagine it would work a bit like Hawking's blink control. Wouldn't have to be much more sophisticated than a Cochlear implant. Of course the only thing that would do is turn your brain into a glorified tracking ball, which might just cut down on the instances of carpal tunnel syndrome--71.247.125.144 16:05, 15 August 2006 (UTC)
- I picture something far more ambitious, many years from now, where you would think of a question ("What's the capital of Sri Lanka ?"), and instantly know the answer, much like AskJeeves worked, when it worked. On the other hand, if it doesn't work, maybe you would instantly see a Columbo movie, LOL. StuRat 19:06, 15 August 2006 (UTC)
- Some kinds of information could be expressed as new senses, e.g. you might feel the state of your bank account as you feel that of your stomach. Me, I'm hoping for a four-dimensional virtual eye. —Tamfang 01:46, 18 August 2006 (UTC)
- No, because it would be wetware. --LambiamTalk 08:52, 15 August 2006 (UTC)
- A brain in a computer or a computer in a brain - both come down to the same problem of useful information exchange. 'Reading' a brain is very crude at the moment. And 'writing', afaik, hasn't gone beyond giving a stimulus to a part of the brain to elicit a response of some muscle. Also very crude. That is getting info out of (or into) a brain, next is making sense of it. So far, all we can say is that 'there is some activity' in some part of the brain when certain functions are performed. We first need to understand the brain, and we're not quite there yet.
- Scientists currently have an implant into the visual cortex which allows the blind to "see" with a grid of points. It's a very small grid right now, so only allows them to see if a person is in front of them, not actually identify the person, but this could be improved to the point where complete images of either the real world or a computer generated world could be supplied to the brain. StuRat 19:01, 15 August 2006 (UTC)
- However, if this were possible, it would open up a path to one of the most desired things, namely eternal life. The machine and the brain would merge. The sum of the two would hold the personality. But the machine can expand indefinitely (in principle) and live forever (and be easily repaired and such). So if the brain would die, that would be like a minor stroke and we would live on inside a computer happily ever after. Also, since we could then interconnect, we would merge more and more and eventually all become one. Cool! Or boring? DirkvdM 09:31, 15 August 2006 (UTC)
- Presumably non-mad scientists are working on it. Check out [2]. 130.188.8.13 13:02, 15 August 2006 (UTC)
Souls in the Great Machine by Sean McMullen. Yup, using brains as computer hardware.Ohanian 13:34, 15 August 2006 (UTC)
So it's not possible for the time being but maybe in 100 years? Thank for the fast reply.
- 100 years seems too short...how about 1000 years? --Bowlhover 01:42, 16 August 2006 (UTC)
- "The machine and the brain would merge. The sum of the two would hold the personality." That supposes that one's personality resides in the brain. I will grant that one's intellect is most likely in the brain, but personality encompasses far more than intellect. Emotion, physiology, one's soul and countless other factors make up a personality. Does anyone know exactly where these qualities exist? Can anyone know? Do they even exist in a physical place at all, or are they trans-physical? I believe merging a computer and a brain might preserve a person's knowledge, but the actual person would not be merged. — Michael J 18:07, 19 August 2006 (UTC)
electric shock abdominator
Oh, does anyone know about those late nite TV ads for those 'abdominator' style muscle toners that you wear like a cummerbund and it gives you electric shocks to induce muscle twitch and supposedly then get you in shape from all the 'exercise' youve been doing? What is that device called?—Preceding unsigned comment added by 211.26.193.93 (talk • contribs)
- I hope you're not interested in buying one. They are utterly useless. --mboverload@ 07:01, 15 August 2006 (UTC)
- There's also one that shocks your face to exercise facial muscles. Sounds dangerous to me. And if you find it difficult to exercise now, just wait until it requires repeated electrical shocks. StuRat 07:16, 15 August 2006 (UTC)
- A mobile version could chase you around and you'd be running for your life - plenty exercise. So once again, StuRat, don't knock it until you've thought it through. :) DirkvdM 09:36, 15 August 2006 (UTC)
- But what is it called folks? The closest I can find (if it's not an abdomenizer) is a microcurrent electrical neuromuscular stimulator.--Shantavira 12:33, 15 August 2006 (UTC)
How do plants defend themselves from microbes?
Since plants don't have a circulation system, what methods do plants employ to defend themselves from microbes? Thanks. --Demonesque 07:08, 15 August 2006 (UTC)
- for starters, Phytoalexin. and don't forget plants do have Xylem. Xcomradex 08:03, 15 August 2006 (UTC)
- And several plants produce pheromones that alert their neighbours they may come under attack. --LambiamTalk 08:49, 15 August 2006 (UTC)
- And some plants have proteases. Eg. pawpaw has something like 50% dry w/w papain which is thought to be a defence mechanism against microbes and burrowing insects. Aaadddaaammm 09:23, 15 August 2006 (UTC)
- And several plants produce pheromones that alert their neighbours they may come under attack. --LambiamTalk 08:49, 15 August 2006 (UTC)
Here's the latest on woad [3] Woad really produces this chemical if you scrunch up some leaves. Perhaps grazing animals and insects don't like blue tongues? --Zeizmic 12:33, 15 August 2006 (UTC)
One defense mechanism is cell death. They kill the cells arounf the microbe and stop it spreading. This results in little spots all over the leaf. The official term is Hypersensitive response [4]. David D. (Talk) 18:30, 15 August 2006 (UTC)
- Not exactly answering the question, but plants are often in close proximity to fungi in the soil, some of which have antibiotic properties, which creates a somewhat safer environment for the plants.B00P 21:18, 17 August 2006 (UTC)
Gravity
If the Sun was to suddenly disappear, light would take so many minutes to reach earth, but would the gravity take affect at the exact time or at the speed of light or slower. I guess what i'm asking is what speed dose gravity travel at?
- Gravity travels at exactly the speed of light. See General Relativity.
- Well, general relativity and string theory both say it travels at exactly the speed of light. If fact I don't think there are any theories of quantum gravity that say anything different and the only theory that does say something different it Newtonian gravity.
- Well we know it doesn't travel instantaneously and it does seem to travel at around the speed of light. --Cyde Weys 18:19, 15 August 2006 (UTC)
- Remember to sign your posts, people! And I can't remember what it the answer was, but i think this has been asked before - check through the archives - i think the title was "speed of gravity". Aaadddaaammm 09:26, 15 August 2006 (UTC)
- Also, see Gravitational Radiation. --Bmk 16:14, 15 August 2006 (UTC)
- You also have to take into account the cause and effect of this sudden disappearance. It is difficult to see how this could happen without an accompanying explosion so big that it would render your question irrelevant. (In other words, hypothetical questions are almost impossible to answer without a lot more detail of various other factors. And even then...)--Shantavira 17:18, 15 August 2006 (UTC)
- The question is, is it possible for the sun to leave faster than the speed of light? I am not expert but I do not know if that scenerio can even happen under the current model of the universe. HighInBC 21:39, 27 August 2006 (UTC)
Bibliography on Wikipedia
I am writing a scientific literature overview in the subfield of AI and will have a compilation of several hundred article titles available, sorted by year of publication/alphabetically. It is often a serious problem to find references to all the work that has been done in a specific scientific field and I think that a list of scientific papers published on a particular topic would be very useful to the scientific community. Authors could add references to their own papers once published etc. and people could contribute missing information, e.g., sometimes the title of the article/paper is known but it is impossible to find out where it has been published or whether it is publicly accessible. Googling for every single publication ever published is a nightmare and in the scientific community we depend on people who are willing to do just that and write a good survey for a widely accessible journal. I think that having a wiki list of published work would be very helpful as it would make surveying the area a bit less obscure and make it easier for young researchers as well.
I am wondering whether this is an acceptable idea for Wikipedia and if anyone else thinks it would be helpful.
- I agree that it would be a good idea, maybe with papers sorted by keywords; although I find the majority of (physics) papers don't list keywords in the abstracts.
- I think the most useful structure would eventually evolve through common effort. If several people knowledgable in the field start contributing, it shouldn't take long before we get a useful database. Lots of research topics are already covered in Wikipedia and one could just attach relevant bibliographies to those.
microbiology
what are the micro organisms useful in controlling air pollution?and in what way?
what are the microbes that produce light?and in what way they are useful?--hima 13:00, 15 August 2006 (UTC)vedula.himaja
- Please take a short amount of time to familiarize yourself with the instructions at the top of the page. We're pleased to help out with most questions, but I'm afraid that we have to ask you to Do your own homework. If you need help with a specific part or concept of your homework, feel free to ask, but please do not post entire homework questions and expect us to give you the answers. TenOfAllTrades(talk) 13:11, 15 August 2006 (UTC)
- it is not at all a home work question....it is asked in one of my descriptive exams...ive been searching it from hours on net so ive kept it here
- Google is an effective search tool. For your first question, searching with the keywords microbes control air pollution will pull up a number of relevant links. A similar search should lead you to answers to your second question, bioluminescence will also be helpful. TenOfAllTrades(talk) 13:48, 15 August 2006 (UTC)
what is PRBS
In Telecoms there is a method of testing circuits by using PRBS. What is PRBS and what is the difference between PRBS23 and PRBS15 etc. Thank You
PRBS stands for pseudo random binary sequence and is intended to simulate random data being sent. The 15 or 23 could refer to the word length but Im not sure.--Light current 18:10, 15 August 2006 (UTC)
- A PRBS can be generated by a linear feedback shift register. It's a kind of pseudorandom noise. It has statistical properties similar to random data--for example, different run lengths of 1's and 0's occur with the expected frequencies, and the autocorrelation of a PRBS with a delayed version of itself is 0 (unless the delay is a whole number of periods). The number usually refers to the length of the shift register. The length of a PRBSn pattern is . Xilinx has some good application notes on how to setup the LFSR to generate different lengths of PRBS pattern.-- The Photon 02:32, 19 August 2006 (UTC)
Leuconostoc and Weissella
These microorganism are useful for what purpose ? Thanks
- Knowing nothing about the genera in question, and with the risk of seeming a smartass, I'd say the obvious answer is "making more of themselves". —Ilmari Karonen (talk) 15:12, 15 August 2006 (UTC)
- Did you read Leuconostoc? There is at least one answer there.--Shantavira 17:22, 15 August 2006 (UTC)
- Leuconostoc can also cause some pretty bad infections in humans - InvictaHOG 09:47, 24 August 2006 (UTC)
Do insects have brains?
This is the dumbest question I asked. I'll be happy if you answer me.
Himanyo 17:51, 15 August 2006 (UTC)
- Yes. very small ones to fit inside their heads (probably)--Light current 18:08, 15 August 2006 (UTC)
- Read brain, especially the section on invertebrates.--Shantavira 18:16, 15 August 2006 (UTC)
- Although calling it a "brain" might be a bit too generous, perhaps "nerve cluster" ? StuRat 18:49, 15 August 2006 (UTC)
- The correct term is ganglion or ganglia. The illustration in the insect article would possibly be more helpful than the brain article. BenC7 23:36, 15 August 2006 (UTC)
- I once read a very interesting book about the apparently very clever things insects can do being due to the following very simple and ingenious rules, things that could be encoded onto only a few neurons I imagine. Sorry, I've forgotten the title and author. Humans, on the other hand, have the overheads of language, and a model of the world enabling them to reason. They need a big brain to code things into language and also maintain a model of the world. (They have a much more complicated software programme than ants - ants are just machine code.) Without these overheads ants can do similarly clever things by instinct which can be encoded compactly into a small brain.
- Then there is the "hive mind", where the modest brainpower of each individual combines to do things collectively, which no individual could do alone. In humans, for example, no human could go to the moon alone, but collectively, we can do it together. StuRat 23:10, 18 August 2006 (UTC)
- I think in ants at least, the ants are again just blindly following simple but ingenoius rules. I have been thinking that a statistical software program is smarter than humans, but because it does not encode things into language or reason then it does not seem so.
New Pollen?
I live in the commonwealth of massachusetts. Ive never had allergy problems before. However, just recently, Ive been displaying symptoms of allergic reactions. Nasal congestion, swollen face, etc. So Ive looked at differnt pollen websites and cant find any info to help me. SO my question is what, if any new pollen comes out around this time of year in the northeast. Ive been fine all summer so it must be some plant/weed that gets release mid to late summer. Of course there is always the chance that I just recently became allergic to something. I know the whole deal how none of your are doctors and I should seek medical attention for real help, so lets just get past that.
THanks!!!
There is a section on the weather page of the Globe that gives a pollen count for the next day or two, maybe you should see if your discomfort follows a trend that parallels this count. For what it's worth, people develop new allergies all the time. Isn't IgE a bitch?Tuckerekcut 00:04, 16 August 2006 (UTC)
- The most prevalent pollen allergen in the northeast US at this time of year is ragweed.--Mark Bornfeld DDS 00:17, 16 August 2006 (UTC)
Treatment of Erythrasma skin rash
I take as read all the precautions etc about this kind of medical advice.
I saw a dermatologist today and she noticed that I had a erythrasma infection in my armpits. It did not seem to be harmful but it can spread. It is, according to my internet research, caused by Corynebacterium minutissimum, a bacteria. She told me to spray it twice a day for a fortnight with Daktarin, which is a UK trade name for a spray powder that contains "miconazole nitrate Ph Eur 0.16% w/w" and which is usually used for the fungal infection known as athlete's foot and other names.
I wondered afterwards why a treatment for fungus would be used with a bacterial infection, and reading the miconazole article suggests that it does have a mild anti-bacterial action also.
But I wonder if I could instead just use an antibacterial spray, as this should be more powerful in zapping the germs. I'm also aware of the nitrates and remember that these are carcinogenic - or is that nitrites?
My question is - is there such a thing as an antibacterial spray that is safe to be used regularly on the skin? I do have some antibacterial creams, but sprays are quicker and more convenient to use. One of them contains chlorhexidine gluconate, which according to the article you should not get near your ears or eyes. The other is based on cetrimide. I want to know more about this before speaking to a pharmacist so I don't end up with something only designed to be used once on wounds. Thank you.
- According to the Merck Manuals, "Topical drugs such as clindamycin and miconazole cream are also effective" [for the treatment of Erythrasma]. For the rest, you should really ask your dermatologist. --LambiamTalk 00:00, 16 August 2006 (UTC)
You can certainly use just about any antiseptic to reduce skin fauna (Clorhexidine and Betadine soaps work well, many spreays and ointments are available), but you don't necesserily want to. Natural microbial fauna might be more effective in keeping out pathological strains than you could be even with diligent cleaning. It may have been that your doctor told you to use the antifungal to reduce the chance of a new infection with fungus, assuming that your body can fight off the erythrasma itself. I would strongly suggest you take the advice of your physician, maybe call her office if you want more answers. If you do decide to go against her advice, though, I would stick to plain old soap and water.Tuckerekcut 00:01, 16 August 2006 (UTC)
- If you truly want to ignore the advice of your doctor (and go with 'free' advice), I find that 100% Tea Tree Oil (Melaleuca Oil) is quite effective for these things. --Zeizmic 13:50, 16 August 2006 (UTC)
defense
what's the best way to defend against terrorism weapons made out of soda or other soft drinks? = >?
- Prohibit production of soda and soft drinks. You can also kill all the terrorists. — [Mac Davis] (talk)
- on a plane, banning them is the best option. People can buy a $1 soft drink on the other side if they want to, or a $2 one guaranteed by the manufacturer on of the plane.
- In public places, it's impossible and pointless. Wjlkgnsfb 22:25, 15 August 2006 (UTC)
- C'mon guys, be serious. It is just plain stupid if you wanted to ban soft drink transportation onto a plane. That is moronic. How would that save lives? All that would do is prove that once again, we give in a little bit more. We sacrifice more of our liberties. — [Mac Davis] (talk)
- lets see you come up with an effective, efficient, cheap detection system to verify that soft drink cans don't actually contain explosives. The simplest solution is to travel light, and buy what you need on the airplane itself or before/after your trip. Wjlkgnsfb 23:13, 15 August 2006 (UTC)
- Unfortunately, defense against soda offers no protection whatsoever against processed cheese or underwear. --LambiamTalk 23:47, 15 August 2006 (UTC)
From the terrorism article: "Terrorism is the systematic use or threatened use of violence to intimidate a population or government...". Nobody even has to get hurt for terrorism to work: it becomes terrorism when the populace is scared. Thousands of people might have died over the course of this era of terrorism, but hundreds of millions of people have to change the way they go about their lives. That is the true effect of terrorism, and they (the instigators) couldn't have done it without us.Tuckerekcut 23:52, 15 August 2006 (UTC)
- People change how they live because they care about living and/or the lifes of others. If that is a "win" for terrorism, the only way to defeat terrorism is to stop caring what happens. No matter how many are kidnapped or killed, just stop caring and terrorism will fail in the end. It is my opinion that not caring if people live or die is terrible, so I feel that is a win for terrorism too. Apparently, terrorism wins no matter what. --Kainaw (talk) 00:57, 16 August 2006 (UTC)
- Sadly, but well said. I think the only way to stop terrorism is to eliminate all the terrorists. And for all you folks following the news out there, I'll give you a hint - the correct answer is not "kill all the terrorists". See hydra for more details. --Bmk 01:14, 16 August 2006 (UTC)
How about special planes for people from Muslims countries ? The terrorists wouldn't see much point in blowing up those planes (that would actually be bad PR for them), and would have a hard time getting onto the other planes. This may seem extreme, but I, and I assume many others, are to the point of just not wanting to fly anymore. I can't bring any carrry-on luggage, and the airlines feel free to lose my luggage and serve me a tiny portion of contaminated water, if any, while keeping me in a hot plane for hours, after waiting in security lines for hours, and they still can't seem to protect us. StuRat 02:03, 16 August 2006 (UTC)
- Which ones are the "Muslim countries"? --68.64.100.100 03:52, 16 August 2006 (UTC)
- Those with a majority Muslim population. Do you need a list ? StuRat 06:45, 16 August 2006 (UTC)
- I believe I once heard that most muslim (and other) terrorist actions take place in the home country of the terrorists and kill mostly muslims. Anyway the question was about terrorists, not muslims. DirkvdM 12:33, 16 August 2006 (UTC)
- And has your fevered brain imagined there is some huge threat from non-Muslim terrorists ? Most people would be entirely satisfied if we could stop Muslim terrorists. All those Buddhist terrorists will just have to wait. :-) StuRat 20:02, 16 August 2006 (UTC)
- My (fevered or not) brain doesn't see much of a threat in terrorism. The attacks, that is, what politicians and the media do is a different matter - they're the real terrorists. I think I have made that clear enough in previous discussions. The total worldwide deathtoll is negligible compared to real threats, like malaria and cars. And the 'war on terrorism', of course. The fact that recently most attacks have been by muslims is at least in part a result of the narrow statistical basis. It may well be that just a few years ago most terrorists were catholics. It takes just a few attacks to tip the balance. Of course the war on terrorism 'helps' here, too. I f you keep on attacking muslims they will keep on counterattacking and you've got yourself a self-fulfilling prophecy. DirkvdM 07:31, 18 August 2006 (UTC)
- So, by your def, the Chechens who blew up the Russian school, children included, are "not real terrorists" and we should just ignore this type of thing ? The facts don't support your argument, attacks on US civilians have dropped off dramatically since the war on terrorism began. Prior to that, they were spiraling ever upwards. And you can't just ignore something due to the current death toll, the potential death toll is much greater. Using your logic, AIDS should have been ignored in the 1980's, because the death toll, at the time, was small, even though it was entirely predictable that it would spread and kill millions, just like unopposed terrorism will. StuRat 18:44, 18 August 2006 (UTC)
- Just so we're very clear about how terrible the above suggestion is, the people arrested in the recent 'liquid explosives' plot were mostly British. Those arrested in the Canadian terrorist conspiracy were mostly Canadian. Or are you suggesting that British and Canadians should only be allowed to fly on their own airlines. BA and Air Canada would really like that - they would make a huge profit. DJ Clayworth 17:09, 17 August 2006 (UTC)
How about special planes for muslims and people who won't eat pork? The pork hating terrorist will be very happy to kill their sworned pork hating enemies (the joos) and leave the rest of us alone. We can call the new airline No Pork Airways.Ohanian 04:51, 16 August 2006 (UTC)
- There seems to be a view around here that terrorist = Muslim = terrorist. That may be someone's idea of a sick joke, but it just incites hatred for all Muslims, the vast majority of whom have nothing but abhorrence for terrorism. JackofOz 10:46, 16 August 2006 (UTC)
The only terrorists I fear are those who don't eat pork. I propose a new airline where the interior of the planes are laced with lard. And all the drinks contains traces of lard. I feel safer in the plane this way. Ohanian 14:49, 16 August 2006 (UTC)
- Alas, that is not just 'around here'. After the end of the USSR, the US (and other western countries) needed another enemy (to distract from interior problems). The attacks on the WTC and the pentagon were a godsend. The only problem was that it's an enemy you can't point out easily. So first Al Qaeda was invented (the term is a US invention), but that was too small and hard to fight, so it changed to 'muslims in general'. Nice and identifiable. DirkvdM 12:33, 16 August 2006 (UTC)
- On a more general note, and this was in a way already said above, the best defence against terrorism is to ignore it. I understand that that was a method used by Thatcher against the IRA (if so, for once she got something right). The point of terrorism is to instill fear. If the media ignore everything you do, there's not point in doing it, so it will stop. So the media and the politicians telling us to be afraid of something that barely kills anyone (if you look at the big picture) are the real terrorists. DirkvdM 12:33, 16 August 2006 (UTC)
- The US tried ignoring it; they ignored the first attack (bomb) on the World Trade Center, they ignored the attacks on the US embassies in Africa, and they ignored the attack on the USS Cole. If they had also ignored the 9-11 attacks, the next attacks likely would have been with WMD. StuRat 20:24, 16 August 2006 (UTC)
- Actually, the US arrested, tried and convicted those responsible for the 1993 bombing of the WTC. They are sitting in a maximum security prison even now. That was before the US just imprisoned suspected terrorists without trials.Edison 17:10, 17 August 2006 (UTC)
- By ignored, I don't mean "took no action whatsoever", that would be beyond stupid. What I meant was "took no action capable of preventing further attacks". Those actions include, but are not limited to, removing the terrorists and their Taliban supporters from their base in Afghanistan. After that was done, terrorist attacks against US civilians dropped off dramatically. StuRat 21:48, 17 August 2006 (UTC)
- Yeah, but we only got peace with the IRA by talking to them. And I don't think the current threat is organised enough for there to be anyone worth talking to about it. And to the 'hilarious' suggestions of all-muslim-country airlines, the problem is 'home-grown' terrorists. Skittle 13:18, 16 August 2006 (UTC)
- Home-grown terrorists may be the problem in the UK, but not in the US. I don't think any of the 9-11 attackers were born in the US. The UK needs to arrest all the clerics who preach terrorism, and keep them locked up, to stop the home-grown thing. StuRat 20:18, 16 August 2006 (UTC)
- What you mean arrest people for saying things you disagree with? So much for Land of the Free, Home of the Brave. DJ Clayworth 17:12, 17 August 2006 (UTC)
- The Right to Free Speech most definitely does not include the right to advocate murdering civilians, as I'm sure the voters would agree in any referendum. StuRat 19:30, 17 August 2006 (UTC)
- A bit more on the IRA broadcast ban. That was also aimed at Sinn Féin, a law that forbade tv and radio (not newspapers) to air comments by Sinn Féin members, so it was more of a political thing. They could be shown, however, so the BBC decided to show the interviews and have the voices dubbed over, thus circumventing the law. So een though the basic idea made sense, it was halfharted, misdirected and done to hastily, not in cooperation with the media, which only pissed them off. Don't ever do that to the media. It will always backfire - they're too powerful, which is a central issue here. There's a little bit on this way at the bottom of Prevention of Terrorism Act (Northern Ireland). Could do with some expansion (maybe a separate article even), but I know too little to write that.
- But most importantly, the ban drew so much attention that it actually hepled the IRA get more attention. Just as the whole war on terrorism now is a godsend for terrorists all over the world. They only need to plan a terrorist attack and make sure they are found out. I wonder if that is what was done here. DirkvdM 13:32, 16 August 2006 (UTC)
No offense everyone, but this wasn't really a science question to begin with, and I doubt turning this topic into a political message board is a good idea...Honsetly, let's nip this now and focus on more seagull bagel & masterbation questions. Can't get enough of those... -- Scientizzle 15:53, 16 August 2006 (UTC)
- Back to pop-bottle explosives then, there's an interesting article in The Register today about the chemistry of making binary liquid explosives. Ojw 21:30, 17 August 2006 (UTC)
What is the difference between group velocity and phase velocity?
Despite reading the articles I am still not clear what the difference is between Group velocity and Phase velocity, relating to waves and sound. Could anyone explain it in simpler laymen's terms please?
Before reading the article I never knew these existed, despite having a GCE A-level in physics, grade B. 62.253.44.31 22:37, 15 August 2006 (UTC)
- The phase velocity is the velocity at which a wave of a single frequency will propagate. The phase velocity is the velocity with which most people are innately familiar; "wave velocity" or "velocity of propagation," really means "phase velocity." When you combine waves of several different frequencies, something different happens: you get interference. In an extreme example, you can combine several waves such that they cancel out everywhere except in a small area of space. This destructive wave interference is by the way, how active noise-cancelling headphones work. The envelope of the resulting "wave packet" is not really a proper wave—it's the result of the interference of several component waves. The envelope of the wave packet, the peak of constructive interference, can travel at a different speed from the phase velocity, the velocity of each of its individual component waves. Group velocity. Get it? — [Mac Davis] (talk)
So if I use an analogy of a long line of cars moving slowly along on a congested road, then would the phase velocity would be the speed the cars are moving at? If one of the cars leaves the road, then the car behind will quickly move up, then the one behind that and so on, so that this gap moves like a travelling wave (or sp? traveling wave) along the line of cars. Would the speed at which this gap moves be the wave velocity?
- I always thought a soliton would be a group wave, until I read the complex article and it totally confused me... --Zeizmic 12:01, 16 August 2006 (UTC)
- The analogy of a line of cars might work, but not as you stated it; it is sort of a complicated analogy since it is a longitudinal wave (i.e. compression wave). Really, the best way to think of group and phase velocity is that the shape of the wavelet changes. The group velocity is sort of the "average" speed of the whole little pulse. The phase-velocity is how fast each frequency component moves. Phase-velocity is different for each frequency component; and it determines how different the pulse will look at the other end. Perhaps even with your physics background, you never got as much Fourier analysis as your colleague electrical engineers; wavelet analysis must use some rigorous mathematical Fourier transforms to get numerical results. Nimur 22:54, 16 August 2006 (UTC)
I didnt realise that different frequencies had different speeds. Now it makes more sense. If this is the case, then why is the speed of sound given as (as far as I recall) 330 metres per second, and not a different speed for specific frequencies? And would it be possible to construct a sound-prism?
So let me see if I get this right please - on an AM radio broadcast, the carrier signal is moving at one speed (the speed of light presumably), but the modulated sound signal is moving at another speed. Is that correct?
And if you drop a pebble into the middle of a large pond and watch the ripples spread out, is it correct that the ripples are moving at phase velocity, not group velocity?
- Yes, yes, and yes... The trick here is that in most materials (i.e., in air, for example), the group and phase velocities are nearly equal. So, when you say that the speed of sound is 330 m/s, you mean that is the average, rough approximation. When the phase and group velocities are not equal, the packet changes shape - this can be detected as distortion. Yes, your AM radio broadcast carrier gets distorted; remember, the speed of light in AIR is less than the speed of light in vacuum (how much less? Depends on the frequency); and if you were unlucky enough to be transmitting through certain types of glass you probably would not be able to recover the original signal. But, for most "normal circumstances" (...if normal means anything in science...) the phase and group velocities are close or equal. Nimur 13:24, 20 August 2006 (UTC)
- Let me give an example of when phase and group velocities are very different: waveguides (image). They are pipes through which you feed electromagnetic waves. A waveguide has a "cutoff frequency" – waves with frequencys lower than that will die out as they try to propagate along the guide. Frequencys above the cutoff do all propagate, but with different phase velocities. If you start at a high frequency and decrease it, the phase velocity will increase. Actually, as you approach the cutoff frequency, the phase velocity will increase to infinity (yes, much higher than the speed of light in vacuum). An infinite phase velocity means that whenever, at one point along the guide, the field has a maximum, it will have its maximum at all other points aswell. The group velocity, however, will always be less than or equal to the speed of light in vacuum. (Otherwise you could send information faster than the speed of light in vacuum, which, as we know, isn't possible.) —Bromskloss 01:57, 21 August 2006 (UTC)
- See [5] java applet--Light current 02:13, 21 August 2006 (UTC)
- Also, phase velocity is w/k whereas group velocity is dw/dk (ie the differential of the phase velocity)--Light current 02:16, 21 August 2006 (UTC)
August 16
"Black threads" in tilapia (edible fish) ?
I regularly eat freshwater, farm raised tilapia. It often contains what I would describe as "black threads". They seem to break apart easily. What are they ? Two thoughts I had were some kind of worm and blood vessels. I cook the fish before eating it, but still, if it's worms I think I'll switch to some other type of fish. I can try to take a pic, but they are quite small and my digicam is so-so, so I'm not sure how well they will show up. StuRat 01:28, 16 August 2006 (UTC)
- Sounds like veins to me. But it would depend on how thick they are. BenC7 04:44, 16 August 2006 (UTC)
- I agree - it sounds like the blood vessels. - Cybergoth 22:36, 16 August 2006 (UTC)
- I think I've seen the same, and I'd say it's veins / blood vessels. Nimur 23:28, 16 August 2006 (UTC)
- Good, I'm not so grossed out now. StuRat 03:39, 17 August 2006 (UTC)
Safety Glasses
I recently sustained an eye injury, and my doctor insists I wear protective lenses to prevent something happening to the other eye and rendering me entirely blind. I've gotten polycarbonate lenses, which work well enough, but a friend of mine (whose father is, he says, a welder) wears a nifty set of dark glasses that are, he claims, actually shop goggles, capable of defending against flying metal debris. I handled them, though, and they seemed like the same sort of thin plastic thing you could get at WalMart. They must have been reasonably high quality, though, since they were so good at cutting out glare without effecting much else. What do you think? If I got a pair, would they really protect me? If so, can anyone offhand point me to a source? Black Carrot 05:44, 16 August 2006 (UTC)
- I think having 100% coverage is more important than the material. So, try to get glasses that cover the sides as well as the front. Most object flying towards the eye can be stopped by any glasses, so long as the object actually hits the glasses. StuRat 07:43, 16 August 2006 (UTC)
Polycarbonate is the toughest thing you can get for protective eyeware. The side-shields are necessary when you are working with flying debris. In Canada, nobody gets away with working on a job site without approved eyeware. --Zeizmic 11:56, 16 August 2006 (UTC)
- They've got great coverage. In fact, that's part of why I'm interested in them - my damaged eye is still very sensitive to light at the edges, even though it doesn't really get an image, so I've been wearing those huge post-surgery shield glasses for awhile. The glasses my friend has, though, hug the edges of the eyesocket, so they keep out just as much peripheral light. As for the material, though, what do you figure these might be made of, and does it sound like they might actually be an acceptable substitute for the approved material? About the worst thing I can think of is having my glasses actually shatter into my eyes. Black Carrot 16:29, 16 August 2006 (UTC)
- Polycarbonate is strong -- it's the stuff they make bulletproof glass out of. And based on the mechanical properties described in the article, it's a very ductile material, so you don't need to worry about it shattering: if something hits your glasses hard enough to go through, it's got enough energy to continue through your brain and exit the back of your skull. --Serie 23:20, 16 August 2006 (UTC)
- Well, right. I recognize that. It's the glasses my friend has that I'm not sure about. I'm asking whether anyone can suggest based on the information I have (related to welding, full coverage, cut out glare, thin and flexible, etc.) what they might be made of, how strong they might be, and perhaps where I can get a pair cheaply if the first two work out. Black Carrot 05:33, 17 August 2006 (UTC)
- Surely the thing to do is to ask your friend where he got them from, and then see if they are marketed there as safety glasses. In Britain I expect they would be marked with something that indicated that they complied with a British standard for safety glasses - but I'm only guessing.
- I did ask him for details, but he couldn't remember any, and I don't remember any obvious markings on the glasses themselves. I've also asked him to see if he can get me a pair, which may or may not happen. I actually posted the question right after I first talked to him, figuring I could get a quick answer and perhaps order them online. Black Carrot 22:01, 18 August 2006 (UTC)
Bananas inducing gag reflex
I have an unusual question, but I'm sure you're used to that around here.
When I eat a banana, it often induces my gag reflex. I have nothing against the taste of banana, and, yes I do chew it (ie. not deepthroating a banana!). Any suggestions what might cause this?
Aaadddaaammm 09:43, 16 August 2006 (UTC)
- Do you get similar sensations from other squishy foods? Sometimes the physical mouthfeel of food can be a very negative sensation. I don't mind the chemical taste of broccoli but the wet slippery squishy slightly grainy feel of it boiled...YUCK! Oh, and thanks for mentioning the chewing issue, that was my first thought when I started reading your question :-) Weregerbil 12:24, 16 August 2006 (UTC)
- Try steaming it, or stir-frying it with a bit of garlic and some salt. Crispy broccoli isn't squishy! :-) Anchoress 05:42, 17 August 2006 (UTC)
- A fellow programmer here had his gall bladder removed. Now, he throws up every time he eats bananas. He doesn't know why (and is upset because he normally had a banana for breakfast every day). I wonder if there is a relation between your problem and his. --Kainaw (talk) 13:00, 16 August 2006 (UTC)
- The old banana gag : peel it and throw it some place, to see if someone shall fall. Please subscribe to a good insurance first :) -- DLL .. T 19:11, 16 August 2006 (UTC)
- Bananas give me a similar feeling (like I want to gag), which is why I don't like them. I attribute it to the texture. Ironically, my husband, who won't eat fresh tomatoes because of the texture, enjoys bananas. --Ginkgo100 talk · e@ 20:24, 16 August 2006 (UTC)
- I feel queasy and often have a gagging reflex when I eat a banana or anything banana flavored. I avoided banana for a long time and eventually mentioned this to an allergist. It turns out that I was diagnosed as allergic to bananas and that this is actually a relatively common symptom for this relatively common food allergy. For me, eating bananas produces no effects (rashes, swelling, etc) other than nausea. Maybe you have the same issue? (The preceding comment is not meant to reflect any medical advise. Please consult your physician.) -- C. S. Joiner (talk) 21:19, 16 August 2006 (UTC)
Two suggestions:
1) Make sure you don't eat any of the little strands that are between the meat and the peel.
2) If the sliminess bothers you, try eating them in oatmeal. I've noticed that this counters the effect, and I don't end up with my mouth feeling like it's coated with slime. StuRat 21:55, 16 August 2006 (UTC)
- I had a cat who would put his ears down and run from the room whenever a banana was peeled, making me wonder what banana-related trauma he suffered before we got him. :-) StuRat 21:59, 16 August 2006 (UTC)
- Lots of cats (such as my cat) do not like bananas either. Nimur 22:49, 16 August 2006 (UTC)
Bananas shouldn't leave your mouth feeling like slime unless they're under-ripe. Try giving them a day or two more before you peel them. (Not too long, though. Waiting till they're black is waiting too long, unless you're making a banana cake). And broccoli should never be boiled. No wonder you find it distasteful. Steaming (and light steaming at that) is the only humane thing to do to a broccoli, if you don't want to eat it raw. JackofOz 01:24, 17 August 2006 (UTC)
- I disagree. All bananas leave a slimy feeling in my mouth. I suspect they have something in them which isn't water soluble (perhaps a potassium compound ?). I rarely eat a plain banana, for this reason. StuRat 03:33, 17 August 2006 (UTC)
- Hmmm. Well, it seems you're not eating the same variety of bananas as I'm eating. Or maybe they use some sort of pesticide or ripening agent over there that affects the taste/texture. I've never had that problem with Australian bananas, and I eat lots of them. JackofOz 09:36, 17 August 2006 (UTC)
- You've apparently built up a tolerance to having slimy things in your mouth. StuRat 19:26, 17 August 2006 (UTC)
- For the sake of common decency, I'll pretend you didn't say that. JackofOz 23:08, 17 August 2006 (UTC)
- I'm talking about the ubiquitous Cavendish banana. Many other people I know have made the same observation about the slimy feel they leave behind. StuRat 18:34, 17 August 2006 (UTC)
- I'm pretty sure we eat Cavendish here too. I still reckon there must be something in the way they're treated before they get to the mouths of the American consumer that makes them that way. Australian bananas are just not like that. JackofOz 23:08, 17 August 2006 (UTC)
- We use carbon dioxide to ripen them, I think. I can't see how that would make them slimy, however. StuRat 00:56, 18 August 2006 (UTC)
- They probably use ethene to ripen them. --liquidGhoul 00:45, 23 August 2006 (UTC)
Numerical study of rotational effects for rotors
Numerical study of rotational effects for rotors It has been recognized that rotational effects can increase lift and at the mean time delay dynamic stall. Studying such phenomenon is very important for predicting rotor performance and optimising rotor shapes. A quantitative study of rotational effects has increasing needs for industrial usage. The project will focus on (1) numerical development of a modified Quasi-3D model based on the previous Quasi-3D model and (2) study the rotational effects at different spanwise distances and different angles of attack. please help me that how to design things(CFD/EFD etc ) that would help me in this research
- When asking for free help, it is best not to cut&paste the exact assignment. Otherwise people might feel that they are being taken advantage of. In fact, I remember there is something about this at the top of the discussion. --Zeizmic 15:18, 16 August 2006 (UTC)
Time course of evolution
Over what period of time or number of generations have evolutionary changes been seen? Specifically, have Sherpas and other peoples living in higher elevations shown genetic adaptation to the high altitude conditions? Thanks!24.5.103.166 17:01, 16 August 2006 (UTC) Scott
- Modern humans are not under as strict selective pressures as other species (due to healthcare, the welfare state, and other societal considerations etc). This, combined with long lifespans, means "evolutionary changes" among humans are very difficult to quantify over generational timescales. Founder effects precipitate "evolutionary changes", but are often not advantageous (evolution does not occur with forethought, remember). There are examples of genetic variation that could, one could hypothesise, shape modern human evolution over quite short generation times, in the absence of modern healthcare. Consider the potential selective advantage of the CCR5-Δ32 allele during a global HIV/AIDS pandemic, for example. Rockpocket 17:35, 16 August 2006 (UTC)
- Outside of humans, there are many animals that have shown changes due to both natural selection (classical evolution) and human-controlled selected (breeding). For example, the common pet hedgehog has an abnormally high chance of being albino because humans have purposely overbred albino hedgehogs. In the natural world, there was an article from National Geographic last month about evolutionary changes in the birds on the Galapagos Islands (the Darwin Species). Also, I recently read about some green-brown tree frogs that are beginning to have the ability to turn white. If it propagates throughout the tree frog population and doesn't die out as a weird mutation, it will be another evolutionary step for them. --Kainaw (talk) 17:51, 16 August 2006 (UTC)
- There's always the same story about birch butterflies growing darker with pollution that darkens boughs. -- DLL .. T 18:59, 16 August 2006 (UTC)
- Bacteria becoming resistant to antibiotics is a form of evolution. And, like Kainaw said, since you didn't specifically ask for natural evolution (natural selection), breeding animals to give them the characteristics we want them to have can also be seen as evolution. Actually, I think that farmers must have come up with the idea of evolution from the time they started doing that, thousands of years ago. The notion of evolution is a whole lot older than Charles Darwin (his father was a protagonist of the idea, for one). DirkvdM 19:02, 16 August 2006 (UTC)
- You mean Charles Darwin's grandfather, not his father (who was an immensely large society doctor, like his grandfather, but not a reknown scientist, unlike his grandfather). Darwin did not invent the idea of evolution, of course, but is the one credited with the development of natural selection in particular as the mechanism of evolution, and propelled it into serious scientific discussion. But in any case selection by itself is not the idea of evolution, per se, which generally indicates population-wide effects and speciation, which breeders generally did not have any grasp of. It is actually quite a conceptual leap from manipulation of passive stocks to the idea that organisms can transmute into other organisms over generations, though it seems obvious once you know it. --Fastfission 00:16, 17 August 2006 (UTC)
- Did I just become a referenced source? [6] Black Carrot 19:54, 16 August 2006 (UTC)
- I don't think so, and if you have, its been misinterpreted. Its unlikely that the tree frogs Kainaw refers to have recently evolved the ability to turn white. Most frogs and reptiles have this capacity so some extent (see chromatophore), they just don't tend to use it that often. Moreover, even if they recently acquire this trait, its unlikely it would become fixed in the population. There would be no obvious selective advantage to it. Infact, it is more likely to be disadvantageous, as the dearth of naturally occuring albinos demonstrates.
- However, there are some interesting examples of pigmentary adaptation that has evolved over (relatively) short time periods. My particular favorite is the Rock pocket mouse. See also a recent study on Peromyscus [7]. Rockpocket 20:18, 16 August 2006 (UTC)
- Actually, it was Black Carrot's question that led me to hunt down the article on white tree frogs in our library. Going from memory, the study (which didn't have conclusions - only study data) showed that tree frogs in northern Florida and southern Georgia were increasingly turning white when on white surfaces. Tree frogs found in other areas turned green. So, they wanted a grant to study if this is an evolutionary step in the tree frogs or have they always turned white and nobody noticed. I don't remember who it was and I don't know if they got the grant. But, I remember the tree frogs turning white. I just remember weird facts and lose the source of them all the time. --Kainaw (talk) 20:16, 16 August 2006 (UTC)
- Sorry, Kainaw, i accidently edited my comment after you reply. The grant you mention is asking the right question, of course, but i would be very surprising if it was a novel adaptive trait. There could be the result of subtle variation in chromatophore distribution or hormonal control. However, if this was a genuine novel trait, i would guess it is a subsequence of selection for another function of the gene involved, rather than selection for the colour change per se. This is usually the case with pigmentary variations that are not obviously cryptic in purpose. Rockpocket 20:32, 16 August 2006 (UTC)
- Humans do show evolutionary adaptations to different environments. For high altitude, there are three responses. Humans who are from sea-level populations react to high altitude with increased concentration of red blood cells (and thus thicker blood) and a higher respiration rate. I don't remember the details of the other two reactions, but peoples from the Andes mountains have a reaction similar to that of sea-leve peoples, while Sherpas and other peoples from the Himalyan Plateau have a different reaction entirely. The time scales for these changes aren't known, but the Andes changes could not have taken more than 15,000 years. --Serie 23:36, 16 August 2006 (UTC)
- I don't believe there is any evidence that these physiological adaptations are genetically encoded and thus a result of natural selection. Athletes from all populations undergo high altitude training to obtain the same effect. A similar example is from the Moken sea gypsies. This remarkable study showed that Moken children have underwater visual acuity that is more than twice as good as that of European children. This, it was suggested, could be the result of a novel evolutionary adaptation to underwater vision. This would have been an amazing find, but just this year the same authors demonstrated that it is actually a skill that can be learned, irrespective of genetic background [8]. Of course, there is no doubt that human populations have evolved under selective pressures (or the lack thereof) - differences in skin tone between Equatorial and Northern European populations demonstrate that. Its just that correlating positive selection of an allele to phenotype is tricky at the best of times in outbred human populations. Putting a time scale on it is even harder. Rockpocket 01:04, 17 August 2006 (UTC)
- It is common for people to confuse evolution with adaptation. A single person will never ever evolve. All of your evolution was done when your father's sperm hit your mother's egg. Everything after that is mere adaptation. Unfortunately, "evolution" is often used in place of "adaptation" in what should be credible sources. It confuses the issue and fuels the fire for anti-evolution people who want to find any reason at all to prove that science is wrong. --Kainaw (talk) 01:15, 17 August 2006 (UTC)
- It is genetic: that's why a flatlander will react in one way to high altitude, a Andean will react in another, simliar way, and a Himalyan will react in a third, entirely different way. --Serie 21:36, 17 August 2006 (UTC)
- Do you have the primary source illustrating this genetic variation? Rockpocket 06:39, 18 August 2006 (UTC)
- It is genetic: that's why a flatlander will react in one way to high altitude, a Andean will react in another, simliar way, and a Himalyan will react in a third, entirely different way. --Serie 21:36, 17 August 2006 (UTC)
There have been a few recent papers on selection in the human genome in different population, like this one.--Peta 00:19, 17 August 2006 (UTC)
Other things which seem to have evolved recently [9] MeltBanana 00:27, 17 August 2006 (UTC)
Fastfission, you say that "It is actually quite a conceptual leap from manipulation of passive stocks to the idea that organisms can transmute into other organisms over generations." Technical terminology aside, isn't it more likely to be the other way around? People started breeding animals for certain traits because they understood that could be possible. So they had some idea of selection. Extending that to natural selection does require some intelligence, but until not too long ago, intelligence was no guarantee to become a 'scholar', so there must have been quite a few highly intelligent farmers. Over thousands of years quite a few of those must have figured this out. Of course, lack of means to spread the knowledge meant the insight was probably lost when they died, so we won't know about them. But they must have existed. DirkvdM 06:43, 17 August 2006 (UTC)
Two things here. There are examples of Microevolution around, in which the balence of some population of a creature changes because of 'survival of the fittest' events. Examples to look at here might include The Beak of the Finch and the Peppered Moth. As for Macroevolution, the form of evolution in which new species of creature or wholly new characteristics arise, these tend to occur on a hugely longer timescale, mostly longer than we've been studying these things. One exception might be drug-resistant bacteria. DJ Clayworth 17:04, 17 August 2006 (UTC)
how to check qulaity of cyanoacrylate or super glue
i would like to know how do you check the quality of cyanoacrylate used as glue. i want to know the chemical tests possible and the common man's test, if any. what are the basic things to make sure that we get a good qulaity glue. i am looking for a super glue which sets in 1 to 2 seconds. thank you.
- To check, apply a drop to two blocks of glass, press together for two seconds, and try to pull them apart. If you succeed, the glue was not super. --LambiamTalk 18:08, 16 August 2006 (UTC)
- Yes, but if you don't succeed that doesn't mean it is superglue because you might not be strong enough. The basic idea is right though (and rather obvious). I've once seen on Klokhuis (great show - I wrote the stub :) ) how glue manufacturers test this. They glued two strips of wood (or whatever material you want it for) together, overlapping, attached one end to a hook and hung weights on the other end, adding to it until it broke. If the breakage was in the wood, the glue was stonger than the wood, and therewould be little point in making it stronger than that. DirkvdM 19:11, 16 August 2006 (UTC)
living rocks
While watching a presentation on the History Channel called the Grand Canyon the narrator referred to the rocks along the Colorado River as "living rocks." What does the term living rocks mean? James L Barden
- Well, they eat, drink, and love women. — [Mac Davis] (talk)
- Living rocks! Damn straight! Well, except sometimes. --Trovatore 18:37, 16 August 2006 (UTC)
- Living rocks are cactii. I doubt that is what the narrator was referring to. --Kainaw (talk) 18:40, 16 August 2006 (UTC)
- Becuase there aren't any cactii anywhere near the Grand Canyon?--152.163.100.74 18:50, 16 August 2006 (UTC)
- What is a cactius, anyway? —Tamfang 06:41, 17 August 2006 (UTC)
- Becuase there aren't any cactii anywhere near the Grand Canyon?--152.163.100.74 18:50, 16 August 2006 (UTC)
Next one - what are living daylights? DirkvdM 19:13, 16 August 2006 (UTC)
- I have one link that may be tangentially helpful - this PDF file has a section entitled "Blood of the Living Rocks: What Colors the Sandstone Red", but it never really says why it is using that term. --LarryMac 19:24, 16 August 2006 (UTC)
- "Living rock" means "in its native condition and site" OED, e.g. the Sphinx is hewn out of the living rock. So I would guess the narrator meant that what looked like individual rocks were actually part of the bedrock.--Shantavira 19:37, 16 August 2006 (UTC)
- Some other, and possibly more obviously illustrative examples, would be the sculpture of Mount Rushmore, and the Treasury at Petra.- Nunh-huh 19:42, 16 August 2006 (UTC)
I suspect they mean the rocks change over time (from erosion) or appear to change (due to lighting conditions). They could also mean there are living things on the rocks, like lichen. StuRat 21:42, 16 August 2006 (UTC)
- 'Living Rock' appears to be some sort of not-very-scientific jargon that is applied to the canyonlands. [10] There appears to be lots of literature using this, but it is not defined anywhere. By the pictures, I'll go with the natural sculptures carved out of the bedrock.--Zeizmic 23:54, 16 August 2006 (UTC)
EMP's affect on a crystal radio
Would an electromagnetic pulse adversely affect a crystal radio, which uses a passive circuit? --Dynamite Eleven 18:50, 16 August 2006 (UTC)
- I don't see why it wouldn't be overloaded and fried just like any other electronic equipment. StuRat 20:07, 16 August 2006 (UTC)
- Depends how much power was incident on the crystal radio's antenna, of course. Nimur 22:41, 16 August 2006 (UTC)
- In its simple form, a crystal radio does not contain electronic components. It should hold up better than current electronic radios. This is not directly related to its being passive. A sufficiently powerful EMP will evaporate your cast-iron stove; it is all a matter of degree. --LambiamTalk 22:54, 16 August 2006 (UTC)
- It would be really hard to do this to a crystal radio set with truly old-fashioned components, as the components would be pretty large and durable.
A "modern" Crystal radio receiver contains a germanium diode, which would probably be ruined by an EMP. An antique crystal radio might contain a crystal of carborundum or galena, which has sensitive spots found by placing a fine metal "cats'whisker" on various places until a signal is detected. These sensitive spots or improvised diodes, deteriorate over time under the best of circunstances, so I would expect that an EMP would also render such a set inoperative, but it should be possible to find another spot unaffected by the EMP. I would not expect that an EMP would change the crystal structure of all galena found in nature. A good plan for survivalists would be to keep a small transistor radio (am and short wave) inside a steel container which would act as a Faraday cage to provide electromagnetic shielding. The steel would be unlikely to allow sufficient energy to reach the radio to harm it, if it has no external connections such as an antenna, earphone, or power cord.Edison 17:21, 17 August 2006 (UTC)
Even if you're using a crystal diode, it's still not possible to make a radio without wires or a speaker, both of which would be fried by an EMP. Also, keep in mind radios generally have antennae ... which are designed to absorb normally faint radiation. Blast them with an EMP and I think it'd be like a lightning rod. --Cyde Weys 19:32, 17 August 2006 (UTC)
- Even the thin wire in a speaker or inductance coil is tens of thousands of times thicker than the junction in a diode, and millions of times thicker than the components of a modern integrated circuit. An EMP capable of burning out a speaker will be powerful enough to electrocute you through the voltage differential it builds up between your arms. --Serie 21:42, 17 August 2006 (UTC)
Cellphones......and the jammers there of
I remember reading an article, not sure where, about commercial radio frequencies, where the author claimed that your average person with a reasonable amount of engineering experiance could probably buy $11 or $12 worth of electronics from a radioshack and be able to build a device that could blackout all cellphone reception in an area the size of Manhattan, is this true? and if it is, how would you do it?--152.163.100.74 19:08, 16 August 2006 (UTC)
- Flood the frequencies that the phones work on with extremely powerful garbage signals. Not too hard to create, but it will not "black out" the phones. It just makes the phone's signals appear weak in comparison. What I think would be cool is a system that collects signals and then repeats them at higher power on a delay. That should confuse the phones and towers. --Kainaw (talk) 20:03, 16 August 2006 (UTC)
- You could enclose the entire area in a Faraday cage. Some secure agencies have taken to integrating one into their buildings structure, but it's not exactly feasible to build one to block all of Manhattan. It rather sounds like something that an evil genius might devise. Hmm... – ClockworkSoul 20:43, 16 August 2006 (UTC)
- If you were to flood the frequencies enough, all that the mobile phones would pick up would be a load of noise, and no communications. I know this to be true, as I recently stayed on a military singals base, and when they had the radio transmitters on high power, the comms of civilian networks in the area would break down, with mobiles failing to ocnnect or send SMS. Martinp23 20:47, 16 August 2006 (UTC)
- You could enclose the entire area in a Faraday cage. Some secure agencies have taken to integrating one into their buildings structure, but it's not exactly feasible to build one to block all of Manhattan. It rather sounds like something that an evil genius might devise. Hmm... – ClockworkSoul 20:43, 16 August 2006 (UTC)
- Twenty years ago, cell phones used simple technology that could be jammed by sending out high-power at the system operation frequency. Modern cell phones use CDMA, or Code Division Multiple Access, which makes "brute force" jammers very ineffective. So, perhaps ten years ago, a $10 dollar home-made 50 watt sine wave transmitter could jam the system. CDMA is actually extremely effective at evading exactly such high-power, "dumb" jamming (it was developed for electronic warfare; it also serves to prevent thousands of legitimate cell-phone calls from "jamming" each-other.. One feature of CDMA coding is to divert power to frequency sidebands where the jam tone has no effect. To jam such systems, you would need a more sophisticated, digitally controlled jammer, which would cost more than $10 or $20 dollars (perhaps more like... several tens of thousands of dollars, or several months to years of home-made re-engineering). In addition, your home-engineer would now need to diversify his expertise from basic analog circuit design to include software, radio frequency electronics, and other areas of expertise. Nimur 22:36, 16 August 2006 (UTC)
- P.S. User:Martinp23 mentions a jammer that exists on a military base. Without doubt, such jammers do exist. However, they operate as I described above (digitally controlled, CDMA-aware systems) and certainly are not home-made. I also doubt their operational range is more than a few hundred yards; if larger areas are covered, it is probably using multiple independent jamming devices. Nimur 22:40, 16 August 2006 (UTC)
- Twenty years ago, cell phones used simple technology that could be jammed by sending out high-power at the system operation frequency. Modern cell phones use CDMA, or Code Division Multiple Access, which makes "brute force" jammers very ineffective. So, perhaps ten years ago, a $10 dollar home-made 50 watt sine wave transmitter could jam the system. CDMA is actually extremely effective at evading exactly such high-power, "dumb" jamming (it was developed for electronic warfare; it also serves to prevent thousands of legitimate cell-phone calls from "jamming" each-other.. One feature of CDMA coding is to divert power to frequency sidebands where the jam tone has no effect. To jam such systems, you would need a more sophisticated, digitally controlled jammer, which would cost more than $10 or $20 dollars (perhaps more like... several tens of thousands of dollars, or several months to years of home-made re-engineering). In addition, your home-engineer would now need to diversify his expertise from basic analog circuit design to include software, radio frequency electronics, and other areas of expertise. Nimur 22:36, 16 August 2006 (UTC)
- I remember as a young schoolboy being told about a simple device made out of turns of wire and a spark gap, that would send out strong radio noise, and also being told not to make one - although I think I did once. I forget the details - but it was like a transformer plus a spark. It required no electronics and worked off batteries. I do wonder though if discussions like this and about explosives are not playing into the hands of terrorists and crank, many of whom must also read Wikipedia.—Preceding unsigned comment added by 81.104.12.10 (talk • contribs)
- You mean a tesla coil? I doubt that would have much of an effect on wireless communications..--205.188.116.74 21:27, 17 August 2006 (UTC)
- Eh - terrorists are getting plenty of practice in the nationwide terrorist training camp we (America) set up over there in Iraq. --Bmk 02:41, 18 August 2006 (UTC)
Ring tones
Ladies and Gentlemen,
This is a question in reference to the wikipedia article entitled "ring tones". When making a telephone call, does the ring tone that the caller hears correspond and occur at the same time the ring of the phone recieving the incoming call? In other words, if the caller hears eight dial tones, will the person receiving the call hear his or her phone ring eight times simultaneously? If not, why?
Thank you for your assistance WJK August 16, 2006
- Not necessarily - it all depends on:
- the length of the ring tone (recieving)
- the length of the ring tone (sending)
- The first one varies according to phone brand/personal preference and the latter according to country. At certain times (when a certain ring tone in a certain country is used), both will be the same, but at most other times they will be different. Martinp23 20:52, 16 August 2006 (UTC)
- If I ring my mobile phone from my home phone, my mobile starts ringing very slightly before I hear the rings in the home phone. The delay is very slight, however. I live in Australia. BenC7 02:21, 17 August 2006 (UTC)
Hair bleaching question
I currently have 3-foot long hair that's a mess of different colours after various dye/bleachjobs over the last couple of years. There's reds, browns, blondes, oranges, bits that look black, etc. In short, it's horrible. Is it possible to simply bleach all the different pigments out of it with peroxide, leaving it white-blonde again? Ta. --Kurt Shaped Box 23:08, 16 August 2006 (UTC)
- From what I'm reading about hair dye, hydrogen peroxide opens up the hair cuticle and allows whatever proteins or compounds that are coloring your hair to escape. If this is true, I wouldn't think it matters whether the color is natural or synthetic as long as it's behaving the same way. And if your hair is as beautiful as you say, would it really matter if your bleach job failed? :D Hyenaste (tell) 23:40, 16 August 2006 (UTC)
- I don't think so, but you should ask a hairdresser. Anchoress 23:51, 16 August 2006 (UTC)
- Depends. How much damage are you willing to do to the structure of your hair? --Serie 00:01, 17 August 2006 (UTC)
I would think you would have more luck dying it black, which can cover any colors already there. And, in the future, only change your hair color when you're on the run from the cops. :-) StuRat 03:26, 17 August 2006 (UTC)
"Only your hairdresser knows for sure." I have heard horror stories of abused hair falling out when over-bleached. Be careful with do-it yourself. See Suicidegirls (They "dyed by their own hand"). Probably easiest to dye it to about your natural hair color and wait for it to grow out.Edison 17:27, 17 August 2006 (UTC)
August 17
Where is the center of earth's land?
Hello,
I was wondering, what is the "average place of land"?
This is how I would define it :
Consider earth as a ball with radius R. Let the origin be its center.
Let A be that part of the surface where there is land.
Define
where is a threedimensional vector from the origin to that point on the surface.
The average place would then be
My guess would be somewhere in Africa?? Evilbu 00:12, 17 August 2006 (UTC)
- Don't think just because it is in the center of the map, it is the center of land. I believe it would be in the Middle East, or the Indian subcontinent, but that's just my mind-model with weighting and the shape of the Earth in mind. Probably more accuratley somewhere in the Indian Ocean. — [Mac Davis] (talk)
- Well, it will be somewhere inside the earth, deep within the surface, by the given definition. Of course I don't know exactly where, but given that the pacific ocean is the biggest region with no land, it will probably be somewhere on the other side from the center of the earth from the Pacific ocean. --Bmk 02:41, 17 August 2006 (UTC)
- Nevermind, I retract that comment. I reread the definition, and it would indeed be on the surface :) --Bmk 03:11, 17 August 2006 (UTC)
- Well, it will be somewhere inside the earth, deep within the surface, by the given definition. Of course I don't know exactly where, but given that the pacific ocean is the biggest region with no land, it will probably be somewhere on the other side from the center of the earth from the Pacific ocean. --Bmk 02:41, 17 August 2006 (UTC)
- I take that the centre of the ball is the origin. Assuming is distinct from zero, the definition given results in a vector of length R, so that is not inside. --LambiamTalk 03:19, 17 August 2006 (UTC)
- Yes, sorry for the confusion. I changed the question, so that it is clear the origin is the center (as I said, assume that earth is a ball)
Does anyone "have" the world in coordinates? Evilbu 16:50, 17 August 2006 (UTC)
There are other ways to go about this... you could find the centre of the largest connected piece of land, for instance. If you wanted to work with lattitude and longitude coordinates, you might have trouble as both coordinate systems wrap around... should the average be adjusted up or down when you add a point? (I can't think of a way to resolve this at the moment.) The one you've suggested sounds good. - Rainwarrior 19:17, 17 August 2006 (UTC)
I wrote a small program in C to calculate this. I used the black pixels in http://visibleearth.nasa.gov/view_rec.php?id=8392, translating the pixels to X,Y,Z coordinates, and taking a weighted average of them (proportional to , with 0 on the equator, and + or - on the poles). The result is 4228.65km beneath the surface, 43°29'41.29" N, 28°7'51.02" E. Here is a link on google maps - sipa1024 23:12, 17 August 2006 (UTC)
- Good work! - Rainwarrior 23:46, 17 August 2006 (UTC)
- Could you explain this process more? most importantly how you got a result at a distance below the earth's surface, given the information available. --Jmeden2000 15:55, 21 August 2006 (UTC)
- The program iterates over all pixels in the image, transforming them to spherical coordinates (r=1,phi & theta in function of row/column in the image), and those spherical coordinates to cartesian coordinates x,y,z. These x,y,z are averaged over all black pixels (by summing them together multiplied with cos(phi), which is proportional to the surface size corresponding with the pixel, en dividing this sum by the sum of all cos(phi)'s). The result is an average x,y,z, which is transformed back to spherical coordinates, and the N & E degrees are calculated from phi and theta, and the depth is earth_radius*(1-R). In the mean time have runned the program again on data from here (43200x21600 image), and the result is 42°22'27.87" N, 29°10'35.38" E, 4244.33 km depth. By the way, evilbu's original question normalised the vector from the center to the average so it was on the earth's surface. I didn't do this, but it's trivial that answer is the same but just at 0km depth :) -- sipa1024 2:01, 22 August 2006 (UTC)
Thank you sipa1024, well done and welcome to Wikipedia! That place is in Bulgaria, about 10 kilometers from Balchik, a Black Sea coastal town. Evilbu 23:30, 17 August 2006 (UTC)
Wikipedia, the encyclopedia anyone can edit....
as long as they have a 4 year degree in math and physics. Isn't it a bit elitest of wikipedia to write all the science and math articles filled with equations and other things that no one can be expected to understand? isn't it contrary to the personal liberty of all peoples that wikipedia should be written in such a way as to restrict knowledge from the common man?--Milboage 00:28, 17 August 2006 (UTC)
- If you don't have an advanced understanding of high maths and physics, why on earth would you attempt to write an edit that required such knowledge? Monolingual Basque people are free to edit this too, but they refrain from doing so because they don't understand it, just as you don't understand integrals and trigonometry or whatever. It's inappropriate to require all physics articles to either stick with basic arithmetic or explain the basics of calculus anytime they need to demonstrate a proof just so Joe Everyman can understand it. Why not take a class or (heh) read up the Wikipedia article if you're so interested in a subject? Hyenaste (tell) 00:44, 17 August 2006 (UTC)
- You can always contribute to the Simple English Wikipedia! --Ed (Edgar181) 01:00, 17 August 2006 (UTC)
- I have often complained about this. I know that no math geeks will ever be able to wrap their brain around this complaint, but I'll try again. Being able to recite an equation is not intelligence. Being able to mix and match equations is not intelligence. It is no more complicated than playing with Legos. Being able to take an equation and explain it without math is intelligence. Einstein wasn't a genius because he looked at a graph of energy to mass ratios and realized that it was a constant relationship with a constant equal to the square of the speed of light. He was a genius because he was able to explain relativity without using equations. Steven Hawking is similar. Read A Brief History of Time and notice how few equations there are. Even when he uses one, he quickly dismisses it and goes on to explain the concept in plain English. Unfortunatly, Wikipedia has a bunch of math geeks who are quick to delete any attempt to explain the equations. Why? They claim, "It is right there in the equation! You don't need to explain it!" They will never understand that it isn't a matter of "need". It is a matter of intelligence - even genius - to explain the math concepts without formulas. So, in my opinion, the math geeks just feel inferior and delete anything that they can't do themselves. --Kainaw (talk) 01:10, 17 August 2006 (UTC)
Isn't math a simplification of English? One equation of medium complexity = a paragraph of english, to use an equation. Math and english can mesh perfectly if you use the right words, but physics professors sometimes lack in that area.
- Well it might help you if you got your words right too. The plural of LEGO is LEGO. No such things as LEGOS. pschemp | talk 03:58, 17 August 2006 (UTC)
- If you think you understand relativity "in plain English", you're wrong. Can't be done. Some of the motivations? Sure. Some of the consequences? Those, too. The theory itself? You're only fooling yourself. Until you get into the equations, you simply don't really understand it, period. And that goes for lots of other things.
- But achieving an understanding of "some of the motivations and some of the consequences", by a large portion of the population, is infinitely better than the majority of the population having absolutely no clue what relativity means, whatsoever, isn't it ? StuRat 07:43, 17 August 2006 (UTC)
- Now, it's a valid criticism that in many cases there is accessible material to present, and it's not presented, or not as clearly as it could be. That's absolutely an area for improvement. But it doesn't mean the specialized material shouldn't be there. --Trovatore 01:24, 17 August 2006 (UTC)
- Math is of extreme importance to some people. Equations are little meaningless symbols that describe the world around us. Einstein was not a genius because he was able to explain relative without using equations, because he was. You can't just say something you know, you have to write it down, and the language of the universe is mathematics. Stephen Hawking mentioned that in his book a few times I believe. His book was popularized physics, meaning it is meant for the sole purpose of mass nonfiction entertainment. Who the hell would want to read a mathbook for fun? Well real mathematicians and physicists do. I do. If you've ever cracked open a college quantum physics text book... there's quite a bit of math. In fact it is almost all integrals, differentials, partial derivatives, and summations and deltas and dot products. The last time I checked M-theory they had a layman, and smartman section :) That's good. — [Mac Davis] (talk)
- I don't think implying that laymen aren't smart is justified. They may very well have higher IQ's than the experts, but just lack experience on this particular topic. StuRat 21:40, 17 August 2006 (UTC)
- I sympathize with both "camps" here - and I think there is plenty of room for compromise. For every complex physics or mathematics article, there can be a full mathematical treatement as well as an English interpretation of the idea intended for those unwilling or unable to go through the mathematics. No need for an "either or", I think. BTW, one of my favorite quotes by Feynman here is that "if you can't explain it to a college freshman, you don't understand it yourself" (inexact quote, too lazy to look up). On the other hand, as someone mentioned, "mathematics is the language of the universe". --Bmk 02:32, 17 August 2006 (UTC)
The issue I see is that some level of simplification is required to make complex topics more understandable to the general public. For example, when explaining atoms, the model of electrons in circular orbits about the nucleus is easiest to understand. The probability wave function, orbital shells and energy quanta concepts should only be introduced after the basics are understood. However, when academics get hold of an article, they frequently delete any simplified explanation because it's "wrong". This leaves the general public incapable of understanding the article. StuRat 02:56, 17 August 2006 (UTC)
- It is wrong, it's much simpler to say that the universe is a large poorly lit christmas bulb that's over 200 billion AUs wide, but we can't put that in an article--71.247.125.144 03:24, 17 August 2006 (UTC)
- So then you're in the camp that says "no simplifications can ever be permitted, and if that means the general public can't understand our articles, well, screw 'em". StuRat 03:44, 17 August 2006 (UTC)
- But it's not a simplification at all, it's simply an older theory that really doesn't mesh well with much of anything any more. Electrons don't orbit around at atom at all, why teach something that's false just because it's easier? If anything, this just makes it harder for people to understand concepts like this once they get to a more advanced level. Hence all the questions from people who think that "spin" is describing the act of an electron physically spinning around an atom..--71.247.125.144 12:51, 17 August 2006 (UTC)
- It's a version which can actually be shown visually, and is all that's needed for basic chemistry, using the outer circular orbit as the valence shell, for example. For most people, this is all they need. For those who go on to theoretical physics, they can learn the more difficult to understand models. For an analogy, globes of the Earth are also "wrong", in that the Earth isn't a hollow cardboard sphere with countries in different colors, but they are still quite useful. StuRat 15:27, 17 August 2006 (UTC)
- Well, no. To have an article on, say, the exterior derivative without equations would be doubly useless: Serious students couldn't get any useful information from it, and casual readers, if they ever cared about such a thing, would have to spend hours reading other dense articles just to understand the "plain English" explanation. Further, as someone pointed out above, though every article can be edited by everyone, not every article should be edited by everyone. You should only edit articles you actually know something about, and if your knowledge of math doesn't go beyond college algebra then you shouldn't be editing math articles. But let me hasten to add that this isn't because math is special, or because I'm a snotty nerd with a math degree. I don't know jack about Hindi phonology, so I don't edit it. The same should go for everyone and every subject.
- I don't know much about Hindi phonology either, funnily enough. But thanks for the mention. :--) JackofOz 09:46, 17 August 2006 (UTC)
- Then how would you like to try to read an article on Hindi phonology which is only understandable by those with a phD in the subject ? StuRat 07:15, 17 August 2006 (UTC)
- That said, there's a good argument for, where possible, giving both a technical and non-technical explanation. The articles on relativity do a fine job of that, as do articles on several other well-known physics topics. Unfortunately that's just not always practical. It really does take a rare talent to convey these advanced ideas in simple ways, and for many of them it's just not worth the effort (see above r.e. "exterior derivative"). --George 05:06, 17 August 2006 (UTC)
- The need for simple explanations also varies by topic. Those which are terms known to the layman, like "atomic theory" or "relativity", are likely to be viewed by laymen, and should thus have at least a portion which is simplified enough to be understandable by the layman. The simple part should come first, with all the equations coming later. On the other hand, topics which are of no interest to anyone but academics can be as needlessly complicated as they choose to make them, it's of no concern to me. StuRat 07:11, 17 August 2006 (UTC)
"The untrained man reads a paper on natural science and thinks: ‘Now why couldn't he explain this in simple language.’ He can't seem to realize that what he tried to read was the simplest possible language – for that subject matter. In fact, a great deal of natural philosophy is simply a process of linguistic simplification – an effort to invent languages in which half a page of equations can express an idea which could not be stated in less than a thousand pages of so-called ‘simple’ language." —Thon Taddeo in A Canticle for Leibowitz
- There are much more fields than science and maths. So you don't need to edit those if you don't get them. While some may need some edits to make them more accessible, I think it's pretty much impossible to write maths articles and articles on some science issues without equations. And some articles will be hard to access to lay men no matter what you do. You can't expect someone without a degree to go indepth into quantum physics, for example. For articles like that you should stick to the intros. - Mgm|(talk) 07:30, 17 August 2006 (UTC)
- Yes, there are "much more fields", like grammar, for example. StuRat 15:42, 17 August 2006 (UTC)
- I doesn't edit those :-) --Serie 21:48, 17 August 2006 (UTC)
- I totally agree with StuRat again for a change (?). Articles should (initially) be written by people who know much about the subject, but they tend to have too little understanding of how little understanding the non-initiated have. So after they are 'done' (which they never are af course - problem) others should copy-edit at least the intro to make that understandable to laymen.
- But this is not restricted to scientific subjects. I've got an ongoing issue over this at British Isles (terminology). I started that article to give people who are confused by the whole terminology (like I was) a simple overview, thus:
- Britain = Great Britain = England + Wales + Scotland (politically) = the largest island (geographically)
- The United Kingdom (political) = England + Wales + Scotland + Northern Ireland
- The British Isles (geographical) = Great Britain (the island) + Ireland (the island) + many smaller surrounding islands
- This may not be entirely correct, but it will instantly clear up a lot of issues for those who haven't a clue. Exceptions to this can then follow. At the moment it's relatively ok because I recently changed it, but over time people will start adding stuff, clogging up the intro, which goes against the purpose of the article.
- More in general, I think an article should start with a simple explanation for the non-initiated and then go ever deeper, so that people can read from the top down until they have reached the point where it goes to deep for them. Of course this is an ideal that is difficult to realise, partly because there also has to be a division in differnt sub-subjects (although that can be largely somved by referring to more specialised articles), but one should try to come as close as possible to that ideal as possible. By the way, the simple English Wikipedia is meant for people who are less proficient at the language, not the subject.
- That said, something that slightly irritates me is writing entities out, like 'kilometres per hour'. Why not 'km/h'? Or can we not assume people to know what that means? But then that's what we have links for. DirkvdM 07:44, 17 August 2006 (UTC)
Music cannot be translated into words without loss of content. Reading the lyrics is not the same as hearing the song. Why should we expect mathematics to be any less rich and deep ? Gandalf61 11:17, 17 August 2006 (UTC)
- Using the music analogy, imagine we are in a world where most people are deaf. Should we say "you can't really understand music, so go away, this article is only for those who can hear". Most people can't understand math formulae either, so an article which only contains those, and no simple explanation, says the same thing to them: "get lost !". StuRat 15:42, 17 August 2006 (UTC)
- Yes, that would have completely killed the soundless music industry, and prevented deaf music from growing into the multimillion dollar business that it is today o: --152.163.100.74 17:15, 17 August 2006 (UTC)
- The deaf can appreciate many aspects of music, like the poetry in good lyrics. They can also "hear" virbations, and have even been known to dance to them. StuRat 18:28, 17 August 2006 (UTC)
- For an example of why 'simple' explanations aren't always right: simple.wikipedia on Heisenberg: that isn't simple, it's wrong, without operators, commutators, and wave functions, certian aspects of QM just can't be translated into plain English--71.247.125.144 13:00, 17 August 2006 (UTC)
- It is completely true that articles should be made at least someone comprehensible to people without advanced degrees. Encyclopedias are meant to be general reference works, not specialized subjects. That being said, one does not have to re-explain the wheel each time if you edit carefully. If I wanted to explain how a nuclear bomb worked, I wouldn't go over all of the details of nuclear fission, what an atomic nucleus was, and so forth, each and every time I brought it up. The linking system makes it easy to reference other topics and allow the reader to go investigate if they are stumped.
- Unfortunately many of our technical/math/science articles are not written with the slightest idea that a non-expert would be wanting to read the subject. Articles are supposed to have introductions which provide context and explain in layman's terms what the rest of the article is to be about. Even something like, "This is useful for solving these sorts of problems," (the latter being linked) is valueable, since it allows one to get someone of an idea of what the point is.
- Obviously you can't re-write all articles to make perfect sense to someone who understands nothing about the subject. But you should be able to make it so that by clicking around, they can get at least a passing understanding of where a given topic fits within a larger field. Many of our articles do this, because people have taken the effort to make them do that. Many unfortunately do not. I am surprised at the stubbornness of some of those who have commented here. The entire point is to share knowledge, and sometimes that means finding ways to explain it that are clear and can be readable by all. Put the general description first ("This principle relates to X and Y, and is useful for Z problems.") and the technical description only after that ("Expressed as the following dozen equations..."). And people who argue that math is clearer than English are obviously and clearly missing the point. Generally speaking our articles should be comprehensible by someone with a little college education. That doesn't mean they should understand the entire article or the details, but they should understand what the article is basically about. --Fastfission 15:48, 17 August 2006 (UTC)
- I agree. Expanding on your note about articles that are missing a simplified explanation - even a simplified introduction. It isn't that nobody is trying to write a simplified section. The math elite are deleting the simplified sections with comments like, "That is already expressed in the formula." The rule should be that even if it is already expressed as a formula, if someone wants to simplify or generalize the topic for the non-formula-reading public, they should be allowed to do so. As it is right now, the math elite are hijacking all math-related articles and fighting hard to keep non-math people out of their private playground with comments like, "If you can't read the formula, you won't understand it anyway." Well, I feel they should all stop using Wikipedia. If you don't know PHP (the scripting language behind Wikipedia) and you don't know the algorithm used to handle diff/patch functions and you don't know server load balancing techniques and you don't know how to create your own TCP/IP packets... you won't understand anything on Wikipedia. So, just go away. --Kainaw (talk) 15:59, 17 August 2006 (UTC)
- Kainaw, as it happens, recently, before your intervention on this page, I happened to be looking at your user page and saw your strongly expressed opinion, and I took a look back through your contrib history to see if I could figure out what prompted it. Couldn't find it. Could you please point me to the example(s) you have in mind, so I can see what you're talking about? It's certainly possible that your characterizations are accurate, for that example (or three); I'm not saying this sort of thing doesn't go on. On the other hand, if you're rephrasing equations literally in English (say, annotating "E=mc2" with "that is, energy equals mass times the square of the speed of light"), well, that's just silly. So I'd really like to see the example. --Trovatore 16:46, 17 August 2006 (UTC)
- Geez, Trovatore, doesn't that sound a bit "nosy" to you ? StuRat 18:12, 17 August 2006 (UTC)
- Honestly, I just don't see it, most wikipedia articles are written well below university level, in terms of the math that they use, if you take an article on something like QED and drop it from a freshman university level, down to a high school level, it loses all meaning--152.163.100.74 17:19, 17 August 2006 (UTC)
- (inserted above next post after edit conflict)
- Look at Zipf's Law - specifically the last paragraph in the introduction. I had to fight for that. Everyone involved kept saying "It's in the equations - just look further down the article, stupid." I said that it is easy to explain in English - without a formula (I don't consider 1/f a "formula"). This went back and forth - even including people telling me that what I wrote is entirely incorrect (though it is a paraphrasing of Zipf's own work). Finally, the paragraph remains and anyone who doesn't understand the "simple" formula has a shot at understanding the 1/f relationship. I ran into the same issue on a statistics page (standard deviation, I believe). Do you need a degree to understand standard deviation? No. Just go through it step by step: Calculate the mean. Subtract each value from the mean and square the result. Average the results. Take the square root of that. I haven't checked the article lately, but I am certain that the clear English description of how to calculate StdDev has been replaced by formulas. I avoid the math articles now because I find the elitist attitude of the math geeks annoying. --Kainaw (talk) 17:49, 17 August 2006 (UTC)
- I just looked at the tuple article and it is written in a way that I like. The intro is clear and easy to understand. Then, there is a Formal Definition section that is heavily laden with math-speak. After that is a Computer Science section heavily laden with pseudo-code. If you don't know squat about math or computers, you can still read the intro and have a firm grasp on the concept of a tuple. --Kainaw (talk) 19:18, 17 August 2006 (UTC)
Any scientific concept can be explained both at a complex mathematical level, such as in a refereed journal or an advanced college textbook, at the lesser level of Scientific American, and at an introductory level such as in TV science programs or illustrated books for scientifically-inclined children. If a practicioner of a field cannot explain the principles of something in words, at various levels of specialized terminology, I question that he really understands it. Electromagnetic wave theory was first laid out by Michael Faraday, who had zero algebra and no ability to write or solve equations. The equations were set down by Maxwell, who discussed the underlying experiments, findings, and predictions with Faraday and wrote that their conceptions agreed in every detail. In a college class in engineering, one student told the professor she could solve the equations and get the right answer, but she did not have an understanding of the phenomena. He said that getting the right answer was all there was to understanding. I beg to differ. A verbal or a physical understanding of the phenomena described by equations contributes meaning beyond symbol manipulation. The calculus equation is often developed long after the laboratory phenomena have been studied. Perhaps the break here is between theoretical physics, say, and experimental physics. I am amused when I read a physics textbook which asserts that Joseph Henry or other 19th century physicists stated thus and such, then the text shows a differential equation Henry never wrote, never saw, and might not have been able to comprehend. Edison 17:46, 17 August 2006 (UTC)
- Since the goal of Wikipedia is to spread knowledge, it's ironic that many of the academics here seem to have the opposite effect (restricting access to knowledge by removing all simplified explanations). StuRat 18:20, 17 August 2006 (UTC)
- I have thought of making the same complain myself. Many articles seem written by mathematicians for mathematicians. While its good to have the maths stuff for those who can understand it, please could people try to include a simpler layman's description at the beginning of the article. After all, an encycopaedia should be about explaining things to people, not just providing a [[precis] of knowledge.
- I still don't understand the complaint, wikipedia articles are already written below the level that they would be taught in a university. Would you suggest an article on spin states that was written for a grade 7 or 8 audience? Most articles are already written at a high school level, and suffer for it. I'll never understand people who are so put off by even having one or two equantions at the bottom of a page that they'll just give up--205.188.116.74 21:41, 17 August 2006 (UTC)
- I am in complete agreement with Edison's comments above. The article should not be limited to either the layman or expert level. All descriptions should be heirarchical, proceeding from the general and "plain english" description, all the way up to the necessary technical details. One does not negate the other. - Rainwarrior 00:42, 18 August 2006 (UTC)
- I would add the following to refocus on the issue: A plain english - even an extremely generalized almost correct description - should be allowed even though it is also repeated in the equations. The complaint continually comes back to the refusal of math-focused editors deleting English descriptions of topics because "it is in the equation". This is not an attempt to remove the equations. It is an attempt to allow non-equation-reading people to get an ounce of insight into math topics and, possibly, take enough interest in them to learn to read the equations. --Kainaw (talk) 13:06, 18 August 2006 (UTC)
- Except that I've never seen anyone do that, ever. The only time people remove 'simplified' text, is when the 'simplification' comes as the result of a severe misunderstanding of the material, where people tend add things like 'common knowledge' to an article. For instance, suppose that a cat, the biological organism, exists only as a mathematical abstraction, now suppose that someone with no knowledge of cats comes along and then tries to add some 'common knowledge' in a factual way, such as, "..It is commonly understood that cats, if they were real, have 9 lives, and can come back to life whenever they feel like it, much like timelords" That's not being removed because it's not an equation, it's being removed because, while simple, is written from the perspective of someone who obviously doesn't understand the topic of the article. And while in the case of cats it would be pretty easy to explain the error to the person in question, but supposing that 'cats' were purely theoretical, and no one had ever seen one in person, then such an explanation would probably degenerate into a philosophical debate on whether you could really prove that cats don't literally have 9 lives. "No, cats may be theoretical, but my model shows that they can't come back from the dead", "no, but you model is all in math, i'm just trying to simplify it, most people don't know math and shouldn't have to", "yes, but cats don't actually have the ability to defy death", "it's close enough, it's just so people can understand cats without having math", "yes, but that's just plain wrong, cats don't literally have 9 lives", etc.....--71.247.125.144 13:30, 18 August 2006 (UTC)
- I would add the following to refocus on the issue: A plain english - even an extremely generalized almost correct description - should be allowed even though it is also repeated in the equations. The complaint continually comes back to the refusal of math-focused editors deleting English descriptions of topics because "it is in the equation". This is not an attempt to remove the equations. It is an attempt to allow non-equation-reading people to get an ounce of insight into math topics and, possibly, take enough interest in them to learn to read the equations. --Kainaw (talk) 13:06, 18 August 2006 (UTC)
Science fiction: stellar explosions and disc formation.
In many science fiction television programs, particularly - in my memory - star trek, when a stellar object such as a planet or star, etc. explodeds the ejecta forms a two-dimensional disc which rapidly expands from the centre of the explosion. Is there a scientific basis underlying this effect, or is it purely artistic license? I looked at accretion disc, but it only appears to deal with collapsing matter, not mentioning ejected matter; ejecta is also no help. Thanks in dadpants,
-somesortamoniker. 88.144.1.63 02:09, 17 August 2006 (UTC)
- Nah, I think it's just for visual coolness. I have nothing to back this up, except the intuition that nothing would cause such a violent asymmetry in the explosion. --Bmk 02:38, 17 August 2006 (UTC)
- I first noticed this in Star Wars, when the Death Star exploded. It had a deep equatorial trench, however, which might be presumed to cause that effect. A rapid rotation might also cause such an effect. In general, however, if a spherical object exploded, I would expect a spherical debris field. StuRat 02:41, 17 August 2006 (UTC)
- I should mention that planets don't usually spontaneously explode, so if they do, there's a mighty funky mechanism at work, probably available only from Starfleet command, which means it could look like anything. --Bmk
- I first noticed this in Star Wars, when the Death Star exploded. It had a deep equatorial trench, however, which might be presumed to cause that effect. A rapid rotation might also cause such an effect. In general, however, if a spherical object exploded, I would expect a spherical debris field. StuRat 02:41, 17 August 2006 (UTC)
- I second visual coolness. — [Mac Davis] (talk)
- When there's gravity and an atmosphere about, there's lots of interesting shapes that explosions can take, mushroom clouds, dust rings. In space, they should probably just explode apart in all directions, and the fires would probably disappear quickly as the oxygen escapes. I think it was just modeled after explosions on earth that produce an outwardly expanding shock wave, and figured it looked more interesting given a planar shape than a spherical one. The earliest one of these I can think of in movies would probably have been from the end of Alien. - Rainwarrior 04:06, 17 August 2006 (UTC)
- It is widely beleived that supernova explosions are one way to produce the transient relativistic jets we see as gamma ray bursts in addition to a general blowing apart in all directions. So instead of a blast along the equator, these would be localized pulses, possibly aligned with the axis of rotation. Dragons flight 07:43, 17 August 2006 (UTC)
Two novas, one of each type. Here, the spherical one looks a lot cooler, I think. DirkvdM 07:55, 17 August 2006 (UTC)
- I think they're both spherical, it's just harder to see a thin spherical shell when viewed straight on (in the middle) than when viewed edge-on. StuRat 15:11, 17 August 2006 (UTC)
- I was thinking the same thing. The fiery ring might just be the edge of a sphere which shows up only because it's thicker from that angle. - Rainwarrior 19:11, 17 August 2006 (UTC)
Why do they taste so nice when I eat them, yet make my stomach feel soo bad up to 12 hours later? --Kurt Shaped Box 05:53, 17 August 2006 (UTC)
- Has every single donair you've ever eaten made you feel this way? If yes, then you might be allergic to something in them. If it's just one vendor, and you don't actually get sick from them, I'd guess either it's that they're using homous and you aren't used to eating beans, or the yogourt sauce (tzatziki, although it has a different name) is a bit off. Anchoress 06:02, 17 August 2006 (UTC)
- The ones round here (UK) are mutton, salad and garlic mayo in a pita bread. I always feel bloated and usually wake up early the next morning with heartburn. I know, I should probably just stop eating the damn things. --Kurt Shaped Box 06:07, 17 August 2006 (UTC)
- Could also be the raw onions (some places use them) or maybe cuz they're so greasy? Some people get upset stomachs from that. Anchoress 06:04, 17 August 2006 (UTC)
- Yup, raw red onions usually - and they are greasy. --Kurt Shaped Box 06:07, 17 August 2006 (UTC)
- If mutton disagrees with you, might I suggest making them out of
seagullbagel meat ? :-) StuRat 06:12, 17 August 2006 (UTC)
- If mutton disagrees with you, might I suggest making them out of
- How many gulls would be required to make up one elephant leg? By all accounts, they're pretty lean birds --Kurt Shaped Box 06:21, 17 August 2006 (UTC)
- The more the better, clean out the whole neighborhood ! :-)StuRat 07:00, 17 August 2006 (UTC)
- Eating
seagullbagels is a health risk because of high mercury levels. It is safer to use rats. --LambiamTalk 09:24, 17 August 2006 (UTC)
- Eating
- ... just not "stu" rats, ok. Those things'll kill ya. :--)
- Yea, once they bite onto something, they just won't let it go. :-) StuRat 01:04, 18 August 2006 (UTC)
- You say that almost as if it's something you're proud of. :--) JackofOz 02:11, 18 August 2006 (UTC)
- Yea, once they bite onto something, they just won't let it go. :-) StuRat 01:04, 18 August 2006 (UTC)
See also Donner Party. Edison 17:49, 17 August 2006 (UTC)
- I always reserve tables under that name at restaurants, I find they don't want to keep you waiting long enough to get hungry, with a name like that. :-) StuRat 17:59, 17 August 2006 (UTC)
- The longer they make you wait, the fewer seats your party will need. --LarryMac 18:01, 17 August 2006 (UTC)
- Yes, but they need an extra plate, for the bones. StuRat 19:08, 17 August 2006 (UTC)
- I know why. Recently I walked past a Donner Kebab establishment, and I saw the cook with part of the grill literally in the gutter of the road next to a rainwater drain where he was 'cleaning' it. I thought at the time that what he was doing must have been illegal as well as being very unhygenic. Even in the UK I suspect such places are not inspected very often and they could have very bad hygiene.
- I feel the same after a doner kebab. However, i have come to realise that it is the copious alcohol imbibed earlier in the evening - a pre-requisit to finding kebaba an attractive proposition - that leads to me feeling sick the following day. Rockpocket 01:46, 18 August 2006 (UTC)
why does water boil at low pressure?
Why does water boil at low pressure? —The preceding unsigned comment was added by Mearom (talk • contribs) 06:17, August 17, 2006 (UTC).
- I assume you are asking why water boils at lower temps, when under lower pressure. This is also true of other liquids. Basically, pressure "pushes" the water molecules together to form a liquid. With less pressure, you reduce this effect. High temps cause rapid movement of water molecules, which makes them "break free" from the bonds that hold the water together as a liquid. So, temp and pressure both interact with each other to determine the boiling point of any substance. StuRat 06:27, 17 August 2006 (UTC)
Figured that, never could find any reference on it, though
- Read our article on Boiling. Already the first sentence kind of explains it. --LambiamTalk 09:34, 17 August 2006 (UTC)
- So pressure and temperature determine the state. Rock melts (becomes a liquid) at high temperatures. The lowest pressure you can get is vacuum. However, rocks in space aren't liquid. Neither an answer nor a question, just playing with some thoughts. DirkvdM 08:03, 17 August 2006 (UTC)
- as far as i know melting point isn't too effected by pressure, since neither phase is in equilibrium with a gas. but i could be missing something obvious... Xcomradex 09:10, 17 August 2006 (UTC)
- The density of a gas is quite different from a liquid, under normal conditions, while the density of solids and liquids are usually similar. In the case of water, the density of the liquid is actually higher, meaning pressurized water freezes at a lower temp. StuRat 15:06, 17 August 2006 (UTC)
A Phase diagram is a good way to see how the phase varies with temperature and pressure, and how changing those conditions affects the melting/boiling/sublimation point. DMacks 16:21, 21 August 2006 (UTC)
poltergiests are in my water!
Sometimes when water is cold and in a bottle, un opened, it rapidly turns to slush upon opening —The preceding unsigned comment was added by Mearom (talk • contribs) 06:52, August 17, 2006 (UTC).
- If it's below the freezing temp (at normal air pressure), the higher pressure in a sealed container may keep it from freezing, until the bottle is opened, then the lower pressure allows it to freeze. StuRat 06:58, 17 August 2006 (UTC)
thank you
- i think the phenomenon has more to do with supercooling. Xcomradex 09:11, 17 August 2006 (UTC)
- The water is supercooled, and agitation initiated nucleation. I've seen this question asked three times before, although it has never happened to me. I am still waiting! — [Mac Davis] (talk)
- Try looking in your beer bottle, rather than your water bottle. ;) pschemp | talk 05:50, 18 August 2006 (UTC)
- The water is supercooled, and agitation initiated nucleation. I've seen this question asked three times before, although it has never happened to me. I am still waiting! — [Mac Davis] (talk)
- I seem to remember at one time not long ago that there wasa type of beer available that was cooled to such anextent that it came out as slush. Very nice on a hot day. I havent seen it around lately.--Light current 16:22, 19 August 2006 (UTC)
biochemistry
can anyone say why ATP is called high energy component compared to ttp ,gtp,ctp??? —The preceding unsigned comment was added by 59.163.146.11 (talk • contribs) 08:11, August 17, 2006 (UTC).
- atp is used quite a bit, but some enzymes specifically use gtp instead. i'm not sure (other than rna/dna synthesis) what the pyrimidine triphosphates are used for. Xcomradex 08:55, 17 August 2006 (UTC)
- As to why this is, it appears to simply be an arbitrary "decision" that was made early in the history of like. I once asked my biochemistry professor the same question, and have since posted his reply to Talk:ATP. It's somewhat lengthy, and has a user reply attached to it that I think you might find illuminating. – ClockworkSoul 19:55, 17 August 2006 (UTC)
FOOD SCIENCE
CAN ANYONE SAY ?WE CONSUME PROTEINS , VITAMINS, CARBOHYDRATES,FATS....DO ALL OF THEM NECESSARY...WE CAN GET ALL OF THEM FROM PROTEINS THEN WHATS THE NEED OF TAKING THEM INDIVIDUALLY??? —The preceding unsigned comment was added by 59.163.146.11 (talk • contribs) 08:15, August 17, 2006 (UTC).
- loud. i suggest you read http://en.wikipedia.org/wiki/Nutrition#Nutrition_and_Health Xcomradex 08:50, 17 August 2006 (UTC)
- First of all, there are essential fatty acids and essential amino acids which your body cannot make from proteins. Secondly, the nitrogen load from eating enough protein to make enough glucose to make enough fat would be prohibitive. There are individuals with inborn errors of metabolism who have to go on diets which restrict certain large groups of nutrients, such as phenylalanine. InvictaHOG 11:53, 17 August 2006 (UTC)
- You cannot live on protein. If you are asking about the Atkin's Diet, than I would like to mention the idea behind that is not that you can live on only protein. — [Mac Davis] (talk)
Underwater Communication
In underwater, for example like in oceans...can the electro magnetic waves be used for communication?...For example.,submarines...If so, then Is UltraSonic wave used only for navigation and detecting of depth?..Can ultrasonic wave be used to send data too?...Also is there any UltraSonic Image procesing system available to detect the object under sea?...
- Yes, electromagnetic waves travel slightly slower in a water medium, but they are used. Ultrasonic waves I do not think can be used for telecommunication although, they do contain information. That is how SONAR works after all... — [Mac Davis] (talk)
- You certainly could send info using ultrasonic waves, using a simple Morse Code, if nothing else. However, I believe subs typically use Ultra Low Frequency radio waves to communicate. StuRat 17:45, 17 August 2006 (UTC)
See Extremely low frequency. Electromagnetic waves of high frequency are absorbed by water. The deeper the receiver, the more absorption. The higher the frequency, the more absorption, IIRC. Dep in the ocean, no light penetrates, and light is just high frequency electromagnetic waves. The U.S. at one time had an extremely low frequency transmitter, 50 hertz or so, to send messages to submerged ballistic missile submarines worldwide.Edison 17:56, 17 August 2006 (UTC)
Do electromagnetic waves really slow down in water? I had always thought that they travel at the speed of light? (What about light? Does light slow down in water as well? Wouldn't it change colour?) - Rainwarrior 19:06, 17 August 2006 (UTC)
- As for changing color, sort of. Light is composed of all colors, and by blocking all colors but blue (in freshwater) and blue-green (in seawater), the color does "change" to become blue or blue-green. Technically, it isn't really a change, though, but rather removing everything else. Compare this to if you had a bowl of M&M's then removed all except the blue ones. It isn't really right to say you changed the color of the M&M's to blue, but, nonetheless, when you look into the bowl, you do see just blue. StuRat 19:14, 17 August 2006 (UTC)
- Err, I didn't mean "sunlight", and that's not what I meant be colour change. Absorbtion I understand. What I was asking is whether EM waves slow down in water, and if they do, shouldn't their wavelength change (thus changing their colour)? - Rainwarrior 19:57, 17 August 2006 (UTC)
- It does travel at the speed of light; the speed of light, that is, in water. Light also slows down in air but not by much. See refraction. I think it only changes color at changes of velocity. AEuSoes1 20:11, 17 August 2006 (UTC)
- All EM waves (including light, of course) slow down in water (or most any other substance, including air), and their wavelengths do change. But, of course, the wavelength will change again when they exit that medium (possibly into your eye), and so it doesn't affect their perceived color. Put another way, the frequency doesn't change as a ray passes through different media, so we can associate the color with the frequency instead for conceptual clarity. It's also worth noting that not all frequencies are slowed by the same amount, and so the wavelengths get bunched up and the light of different frequencies is split into different directions. This is known as dispersion, and is the operating principle of a common prism. Finally, the speed of light is properly the speed of light in a vacuum only; its modern significance comes from its invariance as viewed by various observers rather than its constancy in all environments. However, it is possible to view transparency as an interference effect between waves (or photons) that are in fact propagating at c, so in that sense the waves are travelling at the "true" speed of light, just with some congestion along the way that slows down the actual transfer of energy. Hope this helps. --Tardis 20:34, 17 August 2006 (UTC)
- Ah, so even if you are underwater, because the light has to leave the water and enter your eye, the colour does not change to your perception! Interesting. This is a good answer, thankyou. (I think my confusion was not understanding that they speed up again when leaving the medium.) - Rainwarrior 23:09, 17 August 2006 (UTC)
Thanks Friends..That was indeed helpful.I'm doing an Underwater Autonomous Robot project..It's gonna aid me lot..One more from this discussion is that if Deep water absorbs light and from your saying if it absorbs much of high frequency light waves,then wouldn't the color be appearing as Redish?..<VIBGYOR>.If it absorbs high frequency of light wave, then I presume that the red light having the lower frequency shouldn't get absorbed and hence it should be visible,while Blue color gets absorbed..But why this doesn't happen?..I maybe wrong but I have this doubt for a long while..Plz Help me clear my doubts
- According to Water, water absorbs infra-red, and a tiny amount of visible red. So, no, it absorbs the lower frequency visible light. Rainwarrior 22:39, 19 August 2006 (UTC)
bikini atoll
is it still radio active? —Preceding unsigned comment added by AOL (talk • contribs)
- Please stop asking random questions from AOL proxies--152.163.100.74 17:33, 17 August 2006 (UTC)
-
- Becuase 152.163.100.72 (talk · contribs), one of the 3 proxies AOL gives to the RD/h, keeps spamming that page full of trollish questions, and even inspired a 15 minute block, which of course impacts any other AOL people trying to edit the same page--205.188.116.74 22:05, 17 August 2006 (UTC)
- Every place on Earth is radioactive to some extent. Please read the article on nuclear radiation. — [Mac Davis] (talk)
- Well I think we can be a bit more helpful than that.. I think we can assume he/she means "are the levels of radioactivity there still highly elevated from the nuclear testing which took place there in the 1940s and 1950s?" I assume they mean the entire Pacific Proving Grounds site, not just the Bikini atoll (the Rongerick and Tongelap Atolls were also exposed as a result of testing at Bikini, and testing took place at Enewetak too).
- The water around the atoll is not radioactive anymore. On some islands, though, there are radioactive isotopes (specifically cesium-127) in the soil and plants because of the fallout from the tests. Whether these elevated levels of radiation are dangerous is a matter of dispute, since even elevated they are low levels (and the effects of low level radiation have been disputed for a lonnng time). See this page for a discussion of the different findings. Even if the levels are dangerous, they pose a risk only to people who would inhabit the islands over the long term and who would be eating things grown there. To remove the cesium you'd have to take off the top foot of topsoil or so, or to spread a chemical which will prevent the re-uptake of the cesium. This page goes into some of the options currently discussed. This site has a lot of information on the US radiation assessment program for the Marshall Islands. --Fastfission 17:38, 17 August 2006 (UTC)
- I don't know enough about the medical effects to have an informed answer in general. I do know though that depending on how you tweak the models you end up with very different responses. For example, if I only consider the radioactive effects of being near cesium-137, then there is really almost no danger at all. If cesium-137 is still around then it must be very weakly radioactive (i.e. have a very long half-life). However if we start thinking about injesting cesium-137, then we have to wonder if it is attracted to bones or other organs in particular. I believe, though I wouldn't put money on it, that cesium-137 will bind with bone marrow easily. That's bad, because then you have a weak emmitter sitting inside you in one place for a long time, and over the long run that can lead to cancer. This is why plutonium is dangerous too. It's not that being around plutonium will necessarily make you sick, but if you get it into your lungs it will just sit there and radiate for a decade or so and eventually you will have a much higher chance of developing cancer. So you'd have to know a lot about the specific path of exposure to know for sure what the long term effects are likely to be, because something which is completely innocuous in one situation (i.e. you can eat plutonium without much ill effect, as it will just pass through you, and holding it will do no damage, since your skin can stop the alpha rays) can be very bad in another (i.e. if you breath plutonium, then you could have a real long-term health problem). I think visiting the Marshall Islands is perfectly safe, radiation wise. If I lived there, though, I wouldn't eat the plants on a regular basis, even though the UN/DOE/etc. have assured that they think it is safe. They might be right, but it seems like an unnecessary risk, especially since the effects of low level radiation are, despite decades of research, still very controversial among experts. --Fastfission 19:14, 17 August 2006 (UTC)
- Caesium-137 has some useful information about the biological effects. Here is a CDC report on the effects, too. -- Scientizzle 19:44, 17 August 2006 (UTC)
- Awesome. Yeah, I got the number wrong which made finding info on it pretty hard. ;-) It deposits in muscle, not bone. --Fastfission 20:19, 17 August 2006 (UTC)
- Caesium-137 has some useful information about the biological effects. Here is a CDC report on the effects, too. -- Scientizzle 19:44, 17 August 2006 (UTC)
- I don't know enough about the medical effects to have an informed answer in general. I do know though that depending on how you tweak the models you end up with very different responses. For example, if I only consider the radioactive effects of being near cesium-137, then there is really almost no danger at all. If cesium-137 is still around then it must be very weakly radioactive (i.e. have a very long half-life). However if we start thinking about injesting cesium-137, then we have to wonder if it is attracted to bones or other organs in particular. I believe, though I wouldn't put money on it, that cesium-137 will bind with bone marrow easily. That's bad, because then you have a weak emmitter sitting inside you in one place for a long time, and over the long run that can lead to cancer. This is why plutonium is dangerous too. It's not that being around plutonium will necessarily make you sick, but if you get it into your lungs it will just sit there and radiate for a decade or so and eventually you will have a much higher chance of developing cancer. So you'd have to know a lot about the specific path of exposure to know for sure what the long term effects are likely to be, because something which is completely innocuous in one situation (i.e. you can eat plutonium without much ill effect, as it will just pass through you, and holding it will do no damage, since your skin can stop the alpha rays) can be very bad in another (i.e. if you breath plutonium, then you could have a real long-term health problem). I think visiting the Marshall Islands is perfectly safe, radiation wise. If I lived there, though, I wouldn't eat the plants on a regular basis, even though the UN/DOE/etc. have assured that they think it is safe. They might be right, but it seems like an unnecessary risk, especially since the effects of low level radiation are, despite decades of research, still very controversial among experts. --Fastfission 19:14, 17 August 2006 (UTC)
I prefer women who wear no bikini atoll. :-) StuRat 19:05, 17 August 2006 (UTC)
- Oddly enough, I haven't heard that one yet, despite working on this stuff for a number of years... good job. --Fastfission 19:14, 17 August 2006 (UTC)
- Brilliant. - Rainwarrior 19:59, 17 August 2006 (UTC)
- Indeed, quite witty. Good show, old sport. Black Carrot 19:59, 17 August 2006 (UTC)
Limiting magnitude
Is it possible to see a galaxy (or any other object with a large apparent diameter) if the sky is brighter than its maximum surface brightness?
Also, how much does one's visual acuity affect their limiting magnitude? For example, if I have 20/13 vision and the faintest star I can see is magnitude 4.2, what's the faintest star a person with 20/20 vision can see under the same conditions? How about someone with 20/30 vision? 20/10? --Bowlhover 19:15, 17 August 2006 (UTC)
- I can't understand how anyone could see something less bright than the sky, at the time, no. On a bright day, it's even hard to see a full moon. And visually acuity makes a huge diff, too. An extremely near-sighted person would also find it impossible to see anything less bright than the moon. StuRat 21:31, 17 August 2006 (UTC)
- But if the object's surface brightness is very close to, but just lower than the brightness of the sky - then surely you'll receive (roughly) twice the number of photons from the region of sky with the galaxy, than in the surrounding sky-glow - if you have a sensitive enough telescope/eyes/photon detector, then it's surely going to be possible to measure the extra photons (and hence "see" the galaxy), even though the surface brightness of the galaxy is lower than the background skyglow. Of course the brighter the sky and fainter the surface brightness of the galaxy, then the difference in the overall brightness of the region with the galaxy than the region without is going to become very small and your instruments (or eyes) are not going to be able to pick it out of the background glare. Richard B 20:14, 18 August 2006 (UTC)
- Something that emits twice as many photons doesn't appear twice as bright, however, but only slightly brighter. That's just how our eyes work. StuRat 00:40, 20 August 2006 (UTC)
- True, but it should appear brighter and therefore (theoretically) visible. If you have some sort of photon counter (say, a decent ccd camera), then, provided you get a long enough exposure, then it should be possible to see galaxies with surface brightnesses much lower than the general skyglow.Richard B 12:05, 20 August 2006 (UTC)
- That might work, yes, but I believe the questioner was asking about use of the naked eye to see these things. StuRat 15:55, 20 August 2006 (UTC)
Electrical generator
155.239.56.64 19:43, 17 August 2006 (UTC)Please would you be kind enough to explain to me how an electrical generator produces electricity. Thank you. James. 155.239.56.64 19:43, 17 August 2006 (UTC)
- There are a lot of different kinds of generators, but probably the most common works like an electric motor. If you move a magnet next to a wire, its magnetic field will generate a little bit of electricity in that wire (see Electromagnetic induction). In the generator, usually you have large coils of wire, thus allowing the magnet to stimulate many wires at once. So, some magnets are rotated around next to some coils, and electricity comes out of the coils. Electrical generator will probably explain this better. - Rainwarrior 20:07, 17 August 2006 (UTC)
- Just to clarify, in order for a moving magnet to cause a current in a wire, there must be a circuit - i.e. the wire must be in a loop of some kind - the requirement according to Maxwell is that the magnetic flux be changing over time. There is only magnetic flux if there is a bounded surface (I'm sure Rainwarrior knew this - just clarifying). Basically the magnet creates a non-uniform magnetic field in space, so as the magnet is rotated or moved near a circuit, the magnetic flux changes through the circuit, and an electric current is induced. --Bmk 01:41, 18 August 2006 (UTC)
- Yes, it is extremely important that the wire is part of a closed circuit. Forgot to mention that, thanks. - Rainwarrior 05:00, 26 August 2006 (UTC)
Color of Blood Question
I know that unoxygenated veinous blood isn't blue/purple, but a dark maroon. When a person gets a mid-sized cut on a vein, how long will the blood take to absorb the oxygen in the air and turn a bright red oxygenated color? Please only answer if you have a source or are completely sure. Thanks! Reywas92 20:53, 17 August 2006 (UTC)
- It is immediate. Otherwise, you would at some time have had the fortune of observing blood turn red. You might have cut yourself on a vein that you can see is greenish. — [Mac Davis] (talk)
- Though it should be noted that blood oozing from a wound is still a considerably darker red than arterial blood. In fact, I'm not sure blood from a wound is a noticably different color than blood drawn from a vein (even though the former is exposed to oxygen in the air, and the latter is not). - Nunh-huh 21:13, 17 August 2006 (UTC)
- It takes a little time, maybe a few seconds, it kind of depends on what vein. If the vein is bringing back blood from a well-used muscle that needs oxygen it will look different than if only some of the oxygen is used. This is partially due to the fact that, and read carefully: Hb binds oxygen less actively if it has less oxygen in it. This sounds counterintuitive, but when O2 is put into a red blood cell, it makes that cell want to absorb more O2. So if the blood is deoxygenated, it resists being oxygenated again, so it actually turns from maroon to dark red rather slowly. Once it has a little oxygen, it absorbs more readily, and so it very quickly goes from dark red to bright red. To summarize, as with most things, "it depends..."Tuckerekcut 22:47, 17 August 2006 (UTC)
- Though it should be noted that blood oozing from a wound is still a considerably darker red than arterial blood. In fact, I'm not sure blood from a wound is a noticably different color than blood drawn from a vein (even though the former is exposed to oxygen in the air, and the latter is not). - Nunh-huh 21:13, 17 August 2006 (UTC)
- If you think about the diffusion of oxygen into a volume of blood, there's no physical way it can be immediate. Also, venous blood never looks the same bright red as well-oxygenated arterial blood - I suppose that the blood begins to separate and clot before it is fully oxygenated. And deoxygenated blood can look purplish/bluish - you see this quite often in codes. InvictaHOG 05:33, 18 August 2006 (UTC)
Second Color of Blood Question
My teacher said that when an early doctor sailed to the very hot tropics and took a venous blood sample, he found that it was already red, not dark maroon. My teacher said that it is because the heat of the tropics caused the cells to not accept the oxygen from the red blood cells, causing the red blood cells to go back through the veins still carrying the oxygen, so they are still red. I disagree and say the blood reacted with the air and absorbed the oxygen, turning them red. Who is right? Please only answer if you have a source or are completely sure. Thanks! Reywas92 21:02, 17 August 2006 (UTC)
- What an early doctor said is not necessarily the case. Perhaps there is no need to explain an observation that cannot be replicated! Maybe you should ask your teacher which doctor that was. In any case, here in the 21st century, if we are going to be talking about the oxygen content of blood, it should be measured directly instead of inferred from blood color. Can your teacher provide information about studies on O2 content of blood in the tropics vs temperate climes? - Nunh-huh 21:20, 17 August 2006 (UTC)
- Your teacher sounds wrong to me. If the cells "didn't accept the oxygen", they would die, and so would the person. StuRat 21:22, 17 August 2006 (UTC)
- In fairness to the teacher, his argument would seem to be that the cells' need for oxygen is more than adequately met by the O2 in the blood (which is generally true: blood is not completely desaturated when it returns to the lungs), and that tissue needs less oxygen in the tropics, so the blood is less desaturated there (it is this latter part that seems most dubious). - Nunh-huh 22:06, 17 August 2006 (UTC)
- Your teacher sounds wrong to me. If the cells "didn't accept the oxygen", they would die, and so would the person. StuRat 21:22, 17 August 2006 (UTC)
- At higher temps, chemical reaction rates increase, including organic reactions, meaning even more oxygen would likely be needed, not less. This is the opposite of hypothermia, where reduced oxygen usage has been recorded. StuRat 23:20, 17 August 2006 (UTC)
- The early doctors were usually good observers, and this one was probably right with his observation. The explanation given by the teacher is not that clear, but in a way the heat, the tissue cells and the return of O2 rich blood could be related. I can conceive of severe heat causing an unusual begree of vasodilatation in an effort to increase heat loss. If the gentleman's peripheral circulation was so rapid that the O2 supply to the limb was greatly in excess of the cellular O2 use, this would lead to a raised venous O2 saturation. This effect would be called arterio-venous shunting (of oxygenated blood), meaning that the arterial blood never gets close to the capillaries and surroundings anyway. If the subject were able to maintain an adequate blood volume (i.e. the circulation could be increased without blood volume being a limiting factor), the rise in venous O2 content would be expected, because much more O2 was going to the limb than the cells in the limb needed, and was coming back to the heart unabsorbed by the cells. Note though, that this has nothing to do with the cells not getting enough O2, or somehow being prevented from absorbing the O2. --Seejyb 23:08, 17 August 2006 (UTC).
Article Request: Hemocromotosis
Hello:
I'm wondering if it would be possible to request an article on the topic of Hemocromotosis (a genetic condition which results in excess iron in the blood.)
Information does exist on the web, however, contradictory information exists even between credible sites such as www.mayoclinic.com AND http://www.cdnhemochromatosis.ca/.
A Wikipedia article would be greatly appreciated.
Thank you, Ashley604
- It's the spelling that's the problem. Hemochromatosis. - Nunh-huh 22:02, 17 August 2006 (UTC)
My apologies for the spelling error. That's just how confusing it gets. (The British spell it HaEmochromatosis, further "muddying the waters.") I just can't understand the contradictory information out there between respected peer-reviewed medical journals, and institutions like the Mayo Clinic. ((I have found condtradictions concerning symptoms, genetic prevelance in the population, treatment--other than phlebotomy, and what were the acceptable levels of iron in the blood.))
- No, the root was always haemo. What "mudded the waters" was the Americans dropping the "a" from "ae" dipthongs and the "o" from "oe" dipthongs (eg. encyclopaedia, foetus, faeces, ...) JackofOz 22:43, 17 August 2006 (UTC)
- while there should be rough agreement between lists of symptoms, you shouldn't expect to find identical lists (as we point out, there are a maddening variety of symptoms), or uniformity of opinion on indications for phlebotomy. And prevalence will differ with different populations (and no two studies manage to study identical populations). Some sites may combine more than one mutation in one figure, adding to confusion. For information, you should probably prefer peer reviewed journals over nearly any web site. - Nunh-huh 00:31, 18 August 2006 (UTC)
Engine braking
When driving on a steep downhill road in my home town, I see the following road sign saying:
ENGINE BRAKES PROHIBITED USE LOWER GEAR
According to the Engine braking article, engine braking means turning to a lower gear so that kinetic energy of the car is transferred to faster turning of the engine, and thus slowing car down instead of having to use regular brakes.
I understand that both methods have their advantages and disadvantages - engine braking may mean more noise, but regular braking wears down the brakes.
But as for the sign, in my perception, it contracits itself. The first line says they don't want drivers to use lower gear, and second line says they DO want drivers to use a lower gear. So how should I understand it? - GeNe, 17 August 2006 (UTC)
- What the sign is calling "engine braking" sounds like the use of the jake brake to me. Our article on engine braking is rather vague, and seems to include both the jake brake and using a lower gear, which might be more properly called "transmission braking", and is also a technique advised to use on cars where the regular brakes have failed. StuRat 22:38, 17 August 2006 (UTC)
That article was quite clear. In my car I can slow down on a hill by throwing the automatic into second or low. It works because of the design. Apparently a diesel doesn't have the same physics, so it doesn't slow down quickly just by down-shifting. If you throw the switch to modify the valves, then it can slow down with an enormous noise. So I suppose the 'quiet' way is to approach the slope slowly, rather than rapid downshifting, and then use a low gear. I suppose that keeps the truck slower using rpm-friction. --Zeizmic 23:57, 17 August 2006 (UTC)
- As StuRat has said, the sign is most likely referring to jake brakes, and therefore addressed to drivers of large trucks who would have such equipment on their vehicle. Notice that it does not say "Engine braking prohibited", but "Engine brakes prohibited." The main reason for this is that engine brakes make a lot of noise. This is addressed in the jake brake article. The average automobile driver should feel free to downshift at will. --LarryMac 13:22, 18 August 2006 (UTC)
- A diesel does experience engine braking from just moving to a lower gear just like a regular car. The braking provided by the engine by doing this is not sufficient for steep slopes while carrying heavy loads, though. So an engine brake or Jake brake (a specific brand of engine brake) is used, where the momentum of the truck drives the engine which then compresses air (without fuel) in the cylinder and instead of the compressed air "bouncing" the cylinder back on the down-stroke (using little energy), the air is released through the exhaust valve. This release of the compressed air into the exhaust system is far noisier than the normal operation of the engine. The Jake brake is preferred because over-use of the brakes can cause them to overheat and lose effectiveness or fail entirely. —Bradley 14:55, 18 August 2006 (UTC)
shortwave transmitter
What's the cheapest method you can think of to build a shortwave transmitter?--205.188.116.74 22:44, 17 August 2006 (UTC)
- Depends on what kind of transmission you have in mind. Attach two wires to a battery, scratch the wires against a nail file, will generate a mess of radio frequencies (perform the experiment near a radio to confirm). To send an actual signal see transmitter for a circuit diagram. For a licensable (legal) transmitter see amateur radio operator and the links in there; also visit your local library and book shop for radio amateur books. To set up a SW radio station... uh, I'm out of ideas. What kind of transmitter do you want to build? Weregerbil 06:44, 18 August 2006 (UTC)
- Upon reflection I don't actually recommend you do the battery + nail file experiment. Too many ways things can go wrong: too powerful a battery (the nail file could explode), the experiment shorts the battery which can destroy it (not smart using an expensive cell phone battery), the battery could heat up and do damage, or you could get sparks that hurt you, ... Weregerbil 06:54, 18 August 2006 (UTC)
- What kind of nail file did you have in mind that could explode?! Anyway, connecting one of the wires to the battery via a resistor could save the battery (or would the power loss ruin the transmission?), and I wouldn't worry to much about sparks. —Bromskloss 01:10, 21 August 2006 (UTC)
When is a bird 'born'?
Quick question - help to settle a debate for me (about the date of birth of one of my pet birds, as it goes). When would you guys consider a baby bird to have been 'born' - when the mother bird first laid the egg, or when the baby bird eventually emerged from the egg? I believe the latter - my associate believes the former. --Kurt Shaped Box 22:47, 17 August 2006 (UTC)
- Birds can lay unfertilized eggs, that should answer your question--205.188.116.74 22:49, 17 August 2006 (UTC)
- I would go with the hatch date, too, as a bird is about as developed when it hatches as a person is when born. Need I ask what species of bird we're talking about ? (I'm picturing you wanting to know when to serve the birthday cake, LOL). StuRat 23:02, 17 August 2006 (UTC)
- Just one of my budgies. No, he's not getting a cake. ;) --Kurt Shaped Box 00:44, 18 August 2006 (UTC)
- The wiki article says: "Birth is the process in animals by which an offspring is expelled from the body of its mother." Under this definition, your friend is right. However, this is not always the way things work. If I was counting the birthday of a bird, I would count from it hatching. With my frogs, I count from metamorphosis (when they first leave the water), as the tadpole duration can vary a huge amount. Just use what is most convenient. --liquidGhoul 06:55, 18 August 2006 (UTC)
- I agree with hatching. Some fertilized eggs don't hatch, so in that case you can hardly say the bird was ever born?--Shantavira 07:12, 18 August 2006 (UTC)
- Hence the adage, "don't count your chickens before they've hatched." --Fastfission 16:29, 18 August 2006 (UTC)
How about biscuits, bacon, and scrambled unborn chickens for breakfast?Edison 15:30, 18 August 2006 (UTC)
- No, if you called the laying of the egg "birth", I would think you would call an fertilized but dead egg "stillborn". Regardless, "birth" isn't the correct term in the first place. The correct terms for laying and hatching are, respectively, laying and hatching, which could well answer your question right there. But, if you're using analogy anyway, just pick whichever you think fits best. There are aspects of both that would make "birth" an acceptable metaphor, most of which have already been described. I would, personally, lean towards the date of hatching as a bird's birthday, since the main feature of a birthday to me is that, for the first time ever, a particular being has entered the world of air and openness. I've heard, incidentally, that there are eastern cultures that celebrate the anniversary of a person's conception instead (something to do with astrological significance), so I wonder which one they'd go for. I could certainly see taking the moment a bird's full genetic code assembled as the moment they came into the world, and hence possibly their "birthday". It's not really a biology or vocabulary question, and the right answer is whichever one you think captures the spirit of the thing more. Black Carrot 21:52, 18 August 2006 (UTC)
Phelp's Box
I'm editing an article that talks about a Phelp's Box. It says, "At her birth a host of physical abnormalities were present, including a severe curvature of the spine. As a result, she was forced to spend hours each day and night in what was then called a Phelp's Box, a device that resembled a shallow coffin. Earlier in the century children with severe curvature of the spine were placed in a Phelp's Box and strapped as flatly as possible. The only part of the body that could be moved was the head. It was not only physically confining, but extremely painful as well."
"Phelp's Box" is not in Webster's Third New International Dictionary. It is not in Merriam-Webster's collegiate Dictionary, 11th edition. Google was not helpful either. It had one link that talked about an article similar to the one I'm editing, but the link was no longer active (freegroups.net/groups/pastormail/read/?0::3578 - 13k - Supplemental Result ).
So ... is or was there ever such a device? Does it have a different name now? I'm assuming "earlier in the century" refers to 20th century, not 21st. I do appreciate your help in verifying the facts.
- Here are some more 'torture' devices, but no box. [11] --Zeizmic 00:05, 18 August 2006 (UTC)
- I found one (unhelpful) hit which manages to use two different spellings: I read the story of an invalid girl. One of her several sicknesses was a tendency to for her spine to curve. She laid strapped in a Phelps box. (Philip's box looks something like a coffin.) Possible the story this pastor read draws upon the same source as your article. --LambiamTalk 05:07, 18 August 2006 (UTC)
- It's probably a Phelps brace (not box), named after Winthrop Morgan Phelps, an orthopedic surgeon who focused on bracing as a treatment for things such as scoliosis - he had an interest in cerebral palsy. InvictaHOG 05:26, 18 August 2006 (UTC)
EMP
Supposing for a second that you wanted to generate an EM pulse, and were on a tight budget, how would you do it?--205.188.116.74 00:08, 18 August 2006 (UTC)
- Here's one idea which I thought up, and have never tested, which I'll give you as long as you understand that reading the following represents an agreement that you will never actually do this and if you do it is completely at your own risk and that you understand that you will probably die or blow up your cat or your friends, and you will be arrested and sent to Guantanamo bay and kept there forever: pipe + lots of big gauge wire + bomb + big magnet. Cap the pipe on one end, wrap the heavy wire around the pipe as many times as possible, then connect the two ends, put a fuse in it, pour in a lot of gunpowder, drop in the magnet, light the fuse, and run like heck. The heavier the wire gauge, the better, because it will survive for more of the explosion, and will make a better pulse. Also, note that the idea is not to actually blow up the pipe, just to blow the magnet through the pipe at high speeds. I think that's kind of how the air force does it. I seem to remember they disabled one of Saddam's propaganda TV stations with a similar EMP. And by the way, see the article electromagnetic pulse for more info, and electromagnetic bomb. --Bmk 02:27, 18 August 2006 (UTC)
- I think you just conjured up a graphite bomb. — [Mac Davis] (talk)
Just make sure that whatever you are planning to do with the device, make sure you don't bring a liquid on the plane with you because, as we all know, tomato sauce or cologne never gets out of carpet, being a terrorist weapon, while computers and communications are totally replaceable~
don't ask why you would bring tomato sauce on a plane, unless you want to be a terrorist~
- Bmk you just described a crude form of an explosively pumped flux compression generator, a device used to generate emp pulses in a military setting, among other uses. you might like to read the article for a better way to use bomb + magnet + wire to generate a current pulse. Xcomradex 06:54, 18 August 2006 (UTC)
August 18
six degrees of separation
Virtual Particle
Can a photon be called a virtual particle,as it only acquires mass during interaction,but not during transit?
- The photons that make up light are called "real" or "on-shell" particles; they obey the energy-momentum relation for having zero mass, in that their energy and momentum are equal. "Virtual" or "off-shell" photons are Fourier components of the electromagnetic field with differing energy and momentum; they don't really propagate, but they do cause the Coulomb interaction... at least in the formalism of quantum field theory. I'm not sure what you're asking, but the short answer is that a photon can be either real or virtual. Melchoir 21:54, 18 August 2006 (UTC)
Process Instrumentation and Analyzer maintenance
Dear Japanese brothers and sisters,
Keeping process instruments, particularly in oil refineries, calibrated and online presents numerous obstacles in our country. Does this problem exist in Japan, as well. Thank you for your reply.--202.4.4.23 09:46, 18 August 2006 (UTC)
- Dear anonymous user, in case you are not clear on what this page is, it is part of the English-language Wikipedia, a general online encyclopedia. The people who answer questions on this page are English speakers from all over the world who volunteer to answer questions because of an interest, and usually some expertise, in general scientific topics. The odds of one of them being a petroleum engineer from Japan is probably not all that high, however, so your chances of getting an opinion from such a person by asking on here are not good.
- I've tried to dig up some possible contacts who might be able to put you in touch with people who are able to help you. One relevant web link I was able to find through google was JEMIMA, the Japanese association for electric measuring instrument manufacturers. Also, you might try contacting people connected with petroleum engineering in Japan, for instance, the Petroleum Engineering Laboratory at the University of Tokyo.
- Good luck.--Robert Merkel 12:11, 18 August 2006 (UTC)
negative energy and paul davies
I was reading a book called "how to make your own time travel machine" by paul davies who is a respected physicist[ i read on the book cover anyway i have never heard of him" but in the book he claims that we have the capacity to create an anti-gravity force from the quantum vacuum and an exapmple of this is the casimir effect, apparently it produces negative energy so therfore anti-gravity. what puzzles me is that if gravity is an attractive force and anti-gravity is a repulsive force, then how come the casimir effect produces an attractive force between the two plates? is it something to do with the setup? bernard haicsh and paul davies claim that the casimir effect can be engineered to be repulsive and there could be other effects that are casimir like that produce negative energy and there for repulsivve antigravity, paul davies even cites one which is a single vibrating mirror. is this true? Robinresearch
- well, have you tried Casimir effect, Vacuum energy, Negative energy, or anti-gravity yet?...actually, the last one isn't the best source, but the first 2 should work out--71.247.125.144 12:29, 18 August 2006 (UTC)
Well have been on those no mention of why the casimir effect produces atractive force from what should be an anti-gravitational reaction because it produces negative energy. Looked up paul davies and he is not a controversial physicist, and have gone on NASA website and read that indeed negative energy can produce propulsive force. So it stands to reason that it is possible that if negative energy can be produced by the quantum vacuum there could be an effect that produces more negative energy and therefore more anti-gravity correct? Apparently NASA are looking into this.
However still no mention of why the casimir effect produces attractive rather than repulsive force. Teh casimir effect page says that it is possible for the casimir effect to be repulsive in theory, so that question is answered.
So in summery, negative energy can be produced by the quantum vacuum [zero-point energy], negative energy creates repulsive anti-gravity, the casimir effect can produce repulsive and attractive forces and the casimir effect only produces a small amount of negative energy but theoritically only for now but other reactions that could produce more negative energy from the vacuum and therefore more pronounced anti-gravitational effects are possible. This is not however a free energy source as the activation of enough negative matter would take at least a small bit of energy to cause the reaction that would effect macro-objects. Is all of this correct?
But i still need an answer as to why the casimir effect produces attractive force if it produces negative energy that means it should produce repulsive force. Is it something to do with the mirrors themselves?
Robin research
DVD ram camcorder video movie creation problem
When I try to transmit video from my hitachi dvdcam camcorder(model dzmv550a) from a dvd ram disc to my pc using movie album se software It wont transmit and a flashing hourglass and arrow cursor come up on the screen. What can I do to fix this problem? Thanks Erich
Rubix cube
If you had to design a liquid rubic cube, that would be at least 1x103 orders of magnitude more difficult than a solid state rubix cube, how would you do it? Keep in mind, the only restrictions on this exercise are that it must be liquid, and must also resemble a normal rubix cube in either form or function--71.247.125.144 13:05, 18 August 2006 (UTC)
- First explain what a "Rubix Cube" is and then, what class is this homework for? --Kainaw (talk) 13:49, 18 August 2006 (UTC)
- Do you mean a Rubik's Cube? It is not possible to make anything that has much shape using only liquid.--Shantavira 14:13, 18 August 2006 (UTC)
- No, the X was intentional, after all, there's no such thing as a liquid Rubik's Cube, therefore such a question wouldn't really make any sense--71.247.125.144 14:44, 18 August 2006 (UTC)
- Is there any limit on how viscous the liquid needs to be? --Dweller 15:20, 18 August 2006 (UTC)
- I'm going to say less than 1020, otherwise you could just make the thing out of glass, and that wouldn't be any fun, now would it, so probably anything more viscous than a syrup just wouldn't be sporting--71.247.125.144 15:24, 18 August 2006 (UTC)
- Bah. You spoiled my fun. I think a glass one would be quite attractive. --Dweller 15:29, 18 August 2006 (UTC)
- I'm going to say less than 1020, otherwise you could just make the thing out of glass, and that wouldn't be any fun, now would it, so probably anything more viscous than a syrup just wouldn't be sporting--71.247.125.144 15:24, 18 August 2006 (UTC)
- Didn't I read on this very desk just a couple days ago that all that talk about glass being viscous was nothing but a myth? freshofftheufoΓΛĿЌ 17:13, 18 August 2006 (UTC)
- As I understand it, glass comes in two varieties, glass crystal (like leaded glass crystal) is actually a solid, and doesn't flow, while regular amorphous glass is a supercooled fluid, and does flow (although so slowly that it can be ignored). Glass isn't the only thing with that characteristic, however. Metals are similar. Only crystals are really solid. StuRat 17:29, 18 August 2006 (UTC)
- I was taugh that glass was a liquid, but the glass article says that is a common misconception. --Kainaw (talk) 20:17, 18 August 2006 (UTC)
- As I understand it, glass comes in two varieties, glass crystal (like leaded glass crystal) is actually a solid, and doesn't flow, while regular amorphous glass is a supercooled fluid, and does flow (although so slowly that it can be ignored). Glass isn't the only thing with that characteristic, however. Metals are similar. Only crystals are really solid. StuRat 17:29, 18 August 2006 (UTC)
- Didn't I read on this very desk just a couple days ago that all that talk about glass being viscous was nothing but a myth? freshofftheufoΓΛĿЌ 17:13, 18 August 2006 (UTC)
glass strangely enough, is in fact a glass (aka an amorphous solid). Xcomradex 23:20, 18 August 2006 (UTC)
- Common glass is, yes, but glass crystal, is, as the name would imply, a crystal. StuRat 23:44, 18 August 2006 (UTC)
- true, and the line continues it slow journey to the right hand side of the screen... Xcomradex 00:37, 19 August 2006 (UTC)
- You just need more glass for a wider screen (or even one of those cheap ones with plastic instead of a glass covering). --Kainaw (talk) 00:42, 19 August 2006 (UTC)
- true, and the line continues it slow journey to the right hand side of the screen... Xcomradex 00:37, 19 August 2006 (UTC)
- That's easy. Just suspend several colors of sand in a bottle of water. The challenge would be to get the sand to settle in recognizably stratified layers. Solving the puzzle would involve shaking the bottle a lot and hoping for the best, which is remarkably similar to how I solve a regular Rubik's Cube, with the one exception that, as specified, it would be astronomically less successful. Not that I've ever succeeded that way on a normal cube. Black Carrot 02:32, 19 August 2006 (UTC)
- Oh, and if you want to get pissy about the "must be liquid" rule, you can go ahead and change the sand bit to something else. I'm sure we could find something that has the requisite characteristics. Black Carrot 02:32, 19 August 2006 (UTC)
- You could have a bunch of hollow glass cubes or bubbles connected to each other by valves. In each bubble you could have a different colored liquid which is not miscible with any of the other liquids, and the challenge could be to move the liquids to fit some pattern or something. I think you'd be limited by the number of mutually non-miscible liquids you could find, though. --Bmk 15:29, 19 August 2006 (UTC)
time travel
What experiments could I do about time travel? -- 66.41.55.93 14:36, 18 August 2006 (UTC)
- You could sit in front of your computer for the next 60 seconds, you will have traveled exactly 1 minute into the future--71.247.125.144 14:48, 18 August 2006 (UTC)
- Oh boy, I didn't know that the reference desk would be entertainment :)--Kungfu Adam (talk) 14:50, 18 August 2006 (UTC)
- I seem to recall that in Alice in Wonderland, the faster you ran, the longer it took to get somewhere. Try timing yourself running faster and faster over, say, 1500 metres. <grins> --Dweller 15:31, 18 August 2006 (UTC)
Run a block as fast as you can and run back. Compare yourself to your identical twin. He will have aged more than you by a very tiny bit. Edison 15:36, 18 August 2006 (UTC)
SERIOUSLY you could get two atomic clocks synchonized together. One is left on the ground and one is put on an aircraft which travels around the world. When the clocks are compared after the flight there is a discrepancy. One has travelled in time relative to the other. It was done in 1971 [12] .Also the perehelion shift of the planet mercury is proof that Einsteins theory of relativity works. So I guess you have the last laugh and HAVE asked a relevent question!!
I forgot who the scientist was, but I remember an article in my newspaper about how it may be possible to take an extremly massive object, an put it in a circular path at high velocity and the space inside the circle time will travel slower, so, in say 50 years in the circle 500 years passed. Not sure on reason69.29.78.229 18:06, 18 August 2006 (UTC)
- I wonder if it is possible for a kid to get an airline to allow him to leave a rather accurate clock on a plane for a year. Of course, a kid can't afford an atomic clock, but having a few rather accurate ones is fine. Then, have a few rather accurate ones in his room. In the end, compare the microseconds. That leads to the question that I don't know... how many years of average air travel does it take to lose a single microsecond? --Kainaw (talk) 20:24, 18 August 2006 (UTC)
- I don't know, but it felt like I lost a couple of hours flying from Edmonton to Toronto. - Cybergoth 21:46, 18 August 2006 (UTC)
- MIT student, Amal Dorai, came up with a very elegant way of proving time travel will be possible. He organised the first (and possibly only) Time Traveler Convention. Sadly, as of yet, no traveller has found a slot in their busy schedule to attend. Rockpocket 22:04, 18 August 2006 (UTC)
- You could listen to late night radio, I tuned in at 2:30 a.m. once, and it was "Time Traveler Night." Most of the people who called in said that time travel involed reaching 88 m.p.h. or getting struck by lightning while drinking large quantities of beer.
- I also have a time machine that can travel 8-10 hours into the future once a night. Sadly, the backward travel function is broken.--67.172.248.207 03:03, 19 August 2006 (UTC)
- There is a web site available now on the internet that, once you are logged into it, propels you quite quickly into the future. Again it doesnt work the other way round. Its called wikipedia or something.--Light current 06:35, 19 August 2006 (UTC)
- If anyones really interested in this stuff, I recommend the book 'Black Holes and Time Warps' by Kip S. Thorne (a close friend of Stephen Hawking)--Light current 07:53, 19 August 2006 (UTC)
Standard error
No-one seems to be around on the Mathematics desk and I'm sure you scientists are equally capable of helping me with the question I recently posted there about standard error. Sorry for (almost) cross-posting, but there's an element of time pressure on me. Help gratefully received. --Dweller 14:59, 18 August 2006 (UTC)
- error function (erf) Its related to a gaussian curve isnt it?
--Light current 05:40, 19 August 2006 (UTC)
bioluminescent pigs
Taken from (August 12th): No, but seriously, bioluminescent pigs, how cool is that?--71.247.125.144 15:29, 18 August 2006 (UTC)
Will I be able to find the bacon when the refirgerator light has burned out?Edison 15:37, 18 August 2006 (UTC)
- Pork: the other light meat. --Fastfission 16:26, 18 August 2006 (UTC)
- These are pretty cool too. Rockpocket 21:56, 18 August 2006 (UTC)
- No you'll need to look at the pig under a UV light. David D. (Talk) 22:27, 18 August 2006 (UTC)
- The fish and pigs use the same biotechnology. GFP and its varients can been seen in certain tissues without the need for a UV source. Its much more dramatic under UV, of course. Rockpocket 23:59, 18 August 2006 (UTC)
- Remember daylight does have UV light. GFP needs to be excited to emit. David D. (Talk) 05:27, 19 August 2006 (UTC)
- Of course. Sorry, rereading your answer i now realise your "no" was in response to the refrigerator question. I thought you were commenting on the fact that the the pigs were different from the fish. Rockpocket 05:35, 19 August 2006 (UTC)
- Remember daylight does have UV light. GFP needs to be excited to emit. David D. (Talk) 05:27, 19 August 2006 (UTC)
- The fish and pigs use the same biotechnology. GFP and its varients can been seen in certain tissues without the need for a UV source. Its much more dramatic under UV, of course. Rockpocket 23:59, 18 August 2006 (UTC)
Better link: fluorescent green pig. HenryFlower 22:07, 18 August 2006 (UTC)
question on evolution
could any other animals other than humans evolve to be as smart as humans. Would it happen, as in, could chimps get smarter and eventually be as smart. Also, could humans stimulate animals like birds through enviroment modification to spur evolution in that area?69.29.78.229 18:49, 18 August 2006 (UTC)
- It could happen, yes, but humans most likely prevented this from happening by outcompeting other intelligent animals, like Neanderthals. Think of "intelligent animal" as one ecological niche, which we humans have totally taken over, leaving no room for any competitors. StuRat 18:56, 18 August 2006 (UTC)
- An interesting science fiction series that discusses this topic is the Uplift Universe series by David Brin. --Ginkgo100 talk · e@ 20:20, 18 August 2006 (UTC)
- And, of course, the less interesting Planet of the Apes. StuRat 20:33, 18 August 2006 (UTC)
- Although, in the Uplift Universe, every intergalactic species (except for humans) was artificially bred for intelligence. The rest of the intelligent species in the universe look down on humans for being the only species which had ever done it on their own. Humans are in the process of uplifting chimps and dolphins in the books. Very good series, by the way. User:Zoe|(talk) 23:29, 18 August 2006 (UTC)
- Intelligence is subjective. If I put you in the airport and asked you to tell me which bags had cocaine in them without opening them, could you do it? Humans have selectively bred dogs that have the olfactory sense to do it and the intelligence to use the sense in an intelligent manner. --Kainaw (talk) 20:26, 18 August 2006 (UTC)
- Yeah but if I had a nose as big as a dog, I might stand a better chance. I wouldnt say that was intellingence. THe intelligence comes in knowing that dogs are better at sniffing that almost any other animal.--Light current 17:07, 19 August 2006 (UTC)
- It took more than 200 million years from the emergence of mammals to the genus Homo. So even if all humans were to disappear overnight, it might take some time before some other species picks up on editing Wikipedia again. As to using modified environments, what do you think: Could we stimulate spiders to develop flight through environmental modification? It is not at all clear how we could even start approaching it. And we understand the mechanisms of and pathways to flight a lot better than intelligence. --LambiamTalk 20:44, 18 August 2006 (UTC)
- I would say we already have effected the evolution of other species in many ways:
- 1) Several species have evolved to live with people.
Cats, for example, may have evolved purring as a way to seem cuter than non-purring cats, and thus get more food and shelter from humans.Stricken by me, not a valid example. pschemp | talk 02:43, 19 August 2006 (UTC)
- 1) Several species have evolved to live with people.
- 2) Other species, which seemed like a threat to people, were driven to extinction, such as saber-toothed tigers.
- 3) Other species, which were easy prey for humans, such as the dodo bird, were also driven to extinction.
- 4) Human caused global warming, has, and will continue to, favor some species at the cost of others.
- 5) Pollution favors some species over others.
- 6) Humans have introduced non-native species to many areas, allowing some species to flourish and move into new ecological niches, at the cost of the native species.
- I'd be interested to know how you explain purring pumas. ;) HenryFlower 22:12, 18 August 2006 (UTC)
- I imagine some version of purring existed in many cat species prior to humans, and probably served a social purpose (making the purrers seem less threatening to other pumas, etc.). However, once humans showed up, purring became a very important skill to feline survival, so rapidly evolved from barely audible to quite loud. StuRat 22:24, 18 August 2006 (UTC)
- Cats purr to each other, audibly and probably have done so for a long time. They purr when intereacting with other cat "friends" and most commony when nursing or being nursed on. Since cats likely see humans as a mother or friend substitute, their purring makes complete sense in that context and is probably not affected by humans or an example of evolution. The whole "cats only purr to humans" is a common misconception floating around. Also, evolution is notoriously slow, and the small time domestic cats have been with humans is not enough to make that change. Besides, other small cat species purr. The large cats are however, physically incapable. pschemp | talk 02:40, 19 August 2006 (UTC)
- I imagine some version of purring existed in many cat species prior to humans, and probably served a social purpose (making the purrers seem less threatening to other pumas, etc.). However, once humans showed up, purring became a very important skill to feline survival, so rapidly evolved from barely audible to quite loud. StuRat 22:24, 18 August 2006 (UTC)
- "Would it happen, as in, could chimps get smarter and eventually be as smart." If chimpanzees were specifically bred for intelligence—either by humans or by the needs of nature—then maybe. But it would take many, many, many generations for a chimpanzee to become anywhere near as intelligent as a human being (i.e. it would take a loooong time and you'd need to breed a lot of chimpanzees). It's also highly likely that we'd do it in an inefficient manner—i.e. work really hard to breed chimpanzees who were good at playing chess and then realize that being able to just play chess is not exactly what we meant by intelligence (but perhaps I allude too much to the history of artificial intelligence?).
- "Also, could humans stimulate animals like birds through enviroment modification to spur evolution in that area." Well in intelligence, maybe but the odds are that there are quicker ways for birds to evolve to fit into an ecological niche created by humans, i.e. the way that the common rock pigeon has become such a well-adapted being for living in urban areas in comparison to, say, a hawk. With rapid change to environments on the scale done by humans, though, you'd probably just get a lot of extinction and only a little bit of adaptation, and I'm not sure that adaptation would favor general intelligence in particular. General intelligence is not, as should be clear by the more-or-less lack of it in the animal kingdom, always the best adaptation. If you already know how to fly, the species will probably just become better at that. It takes a lot of specific jumps for general intelligence to be a really powerful adaptation (i.e. the ability to manipulate tools is no doubt up there as a very useful prerequisite—it is something which more general intelligence can be directly applied to with devastatingly powerful results). I'm not sure that sparrow which is only incrementally smarter than other sparrows is unlikely to be able to translate that brainpower into a real reproductive difference. --Fastfission 23:53, 18 August 2006 (UTC)
Gold and Silver
I need to find a table or chart that shows the optical density and emissivity of Gold and Silver. Thanks for any help!
- matweb will give you the emissivity, at least. Apparently the term optical density is ambiguous. You ought to be able to estimate the absorbance from the electrical resistivity given in matweb. That's left as an excercise for the reader. -- The Photon 02:57, 19 August 2006 (UTC)
Nystagmus upon waking
Is it common to have nystagmus upon waking from a vivid dream? It happened to me the other night when I woke suddenly from a nightmare. It had a semicircular pattern with the fast phase to the left. It only lasted a few seconds. In the dream there were a lot of video screens with images flashing rapidly up and down. --Joelmills 22:02, 18 August 2006 (UTC)
- The article states that it is relatively common, although I've never read anything about association with dreams or waking up before. — [Mac Davis] (talk)
Changing DNA on the fly
In Star Trek, every other episode you get a case of characters devolving into monkeys or growing giant brains or turning into spiders because they've had their DNA changed. Presumably, the idea behind this is that if you change a individual's DNA (genotype, I suppose) you can almost immediately affect their phenotype, their outside characteristics. So to use a simple example, if I could somehow change the allele for brown eyes to blue eyes in a human's DNA, at some point (instantly? in days? weeks? years?) the human's eyes would turn blue. I assume the science is that as the iris cells die and are replaced, the new DNA is used to code for the iris colour, resulting in a different colour.
This has always seemed rather dodgy science to me, but it has a spark of believability about it. So the question is: if I change a person's DNA, will it ever change their appearance, etc.? Sum0 22:18, 18 August 2006 (UTC)
- (edit conflict)Of course it will, it just won't turn you into another organism, transcription errors happen all the time, but rather than changing a phenotype in any noticable way, they usually just wind up killing a cell, or even worse, leading to uncontrolled cell growth, aka, tumor formation (David D. beat me to it)--71.247.125.144 22:28, 18 August 2006 (UTC)
If you could change the gene in all cells then you could change the appearance. Cancer cells are an example of mutations that change the genotype and phenotype. Except in this case only a single cell is involved. In star trek i think they usually invoke a virus whivch presumably infects (and changes) all cells. Or maybe only the brain cells in your " giant brains " example. David D. (Talk) 22:25, 18 August 2006 (UTC)
- For some changes, yes, for others, no. Some changes that take place in our bodies are not reversible. Your height, for example, can't decrease by much (it can a little, due to osteoporosis), since there is no biological process in place to remove large bones and replace them with smaller bones. Some changes, however, can take place "on the fly", and don't even require DNA changes, such as changes caused by testosterone injections. StuRat 22:38, 18 August 2006 (UTC)
Aside from your brain, your a totally new you ever 7 years due to cells dying and being replaced. Some cells, like red blood cells, are replaced faster tahn, say, bone.69.29.78.229 23:11, 18 August 2006 (UTC)
- and if you use five ~~~~~ it just gives the date--71.247.125.144 23:13, 18 August 2006 (UTC)
- If you change DNA on the fly, you get... The Fly! --LambiamTalk 01:37, 19 August 2006 (UTC)
- It's important to always take into consideration how DNA works when thinking about stuff like this. Your DNA becomes RNA which becomes a protein (more or less—there are more complications of course). These proteins have big phenotypic effects, some of which are fast (formation of new cells with specific characteristics) and some of which are not. Some things only happen at specific times in your life (i.e. puberty) and will not happen again. It seems unlikely to me that changing the DNA of an already fairly well-developed organism (even if you had a way of changing all of the DNA in all of the cells at the same time) would ever make it able to grow into a super-sized organism. You might be able to, however, change a gene which encourages a never-ending appetite and make them very fat. But even that would be pure speculation that a simple full-organism knock-out would have phenotypic effects which would alter those which had already gone through a long period of development to get to where they were. --Fastfission 04:32, 19 August 2006 (UTC)
Eyes rolling to the back of the head
Why is it that people's eyes sometime roll to the back of their eyes? Also, why do some people's eyes roll back when they die and some don't? 63.23.82.53 22:46, 18 August 2006 (UTC)
- No-ones eyes do, it would detach the nerve, plus the muscle arrangement means nothing over 90 degree rotation in any direction from straight forward is possible. Philc TECI 22:56, 18 August 2006 (UTC)
- I think they just mean rapid up and down, or side to side, movements, not literally 'behind' their head--71.247.125.144 23:07, 18 August 2006 (UTC)
- when you are in non-rem sleep, your eyes will roll slightly so that the apperance of your pupils are in your skull, which, for most people, doesn't happen just some of the pupil is, there are anomolies out there, though, but nobody's eyes are even somewhat capable of even looking towards "the back of the eyes"69.29.78.229 23:16, 18 August 2006 (UTC)
- When you are dead, you become cross eyed. (The optician told me)--Light current 05:36, 19 August 2006 (UTC)
Do it your self X-ray
I've heard stories of people who, while witnessing atomic testing, have held their hand in front of x-ray film, and gotten a clear picture. It sounds sketchy to me, but I suppose it could be true. Is it?--67.172.248.207 23:56, 18 August 2006 (UTC)
- Wouldn't the film be overexposed? or even completely washed out?--71.247.125.144 23:59, 18 August 2006 (UTC)
- not over x-ray film, but over their eyes. common veterans story here from the days of nuclear tests. Xcomradex 00:40, 19 August 2006 (UTC)
- I don't know what an x-ray film is, but if you took an x-ray of somebody's hand, no matter how much nuclear testing they witnessed, it would not be clear picture, that's not how it works. An x-ray works, because bones absorb more of the xray region of the electromagnetic spectrum than surrounding skin, fat, muscle, etc. See the radiation article. — [Mac Davis] (talk)
- It's the "hand over the eyes and see your bones" tale that is usually given. A large part of a nuclear explosion does come in the form of X-rays (which is what drives the compression in a hydrogen bomb), but I have no idea about how true the story is, except that a lot of people have told it, though that hardly makes it true. It strikes me as a little fishy as I think about it, since the human eye can't see X-rays unaided (i.e. without film or a fluorescing screen). A lot of different things are released during a nuclear explosion though so something else could be going on there as well. --Fastfission 04:41, 19 August 2006 (UTC)
- obviously not x-rays, i'd say the enormous amount of visible light released does the trick. Xcomradex 05:06, 19 August 2006 (UTC)
August 19
bee B-gone
I have bees in the top of my house. My exterminator is not successful in killing them. I have sprayed them with cheep store bought spray to no avail. I live in Dallas Tx. I dont know what kind of bees they are. I am too old and scaired of them to get close to them on a ladder. I dont want to use my bug man again. What can I do? Thanks 24.0.47.184 03:11, 19 August 2006 (UTC)
- WHATEVER YOU DO, DO NOT RUN INTO THEM SCREAMING. — [Mac Davis] (talk)
- You could import some Bee-eaters — [Mac Davis] (talk)
- Telsa coils? — [Mac Davis] (talk)
- Okay, I'm not helping. — [Mac Davis] (talk)
- Perhaps try another, different exterminator? Are you sure they are bees and not hornets or yellowjackets? If they are either of the latter then I definitely do not recommend trying it yourself if you have any doubts because they can be very aggressive (bees are not very aggressive in general, but hornets/yellowjackets are and are very territorial, and unlike a bee can sting many times). --Fastfission 04:34, 19 August 2006 (UTC)
- I recommend poison. However, depending on the type of bee, wasp, or hornet, a different poison may be indicated. If you can manage to kill one, look at it up close and compare with pics online or in a book to identify the type. A good exterminator should have identified the species, too, but it sounds like you had a lousy exterminator (perhaps literally), so he may not have done that, either. Once you've identified the species, go online and do a Google search for the best poison. Ideally, they should take it back to the hive and kill the queen, too. StuRat 05:49, 19 August 2006 (UTC)
- Dont bee keepers use smoke to make the bees dopey when they are moving the hive--Light current 05:58, 19 August 2006 (UTC)
- You could try smoking Hamlet cigars. (2B or not 2B TITQ)--Light current 06:10, 19 August 2006 (UTC)
- Smoke makes them leave without becoming angry, since they don't blame anyone for a fire. But they would just return once the smoke clears. You need them dead. 07:50, 19 August 2006 (UTC)
- Call your local fire department. Sometimes, they'll come to spray them with soapy water. At least, that's what they did one time in my house. Titoxd(?!?) 07:53, 19 August 2006 (UTC)
- What? Hes not trying to give them a bath!--Light current 07:57, 19 August 2006 (UTC)
- IIRC, it destroys the beehive. Titoxd(?!?) 08:10, 19 August 2006 (UTC)
- What? Hes not trying to give them a bath!--Light current 07:57, 19 August 2006 (UTC)
- surely its better to get a proper bee keeper to move the bees to a new hive! Bees are very useful creatures you know!--Light current 08:18, 19 August 2006 (UTC)
- Yeah that it! Found on bee keeping page. Smoke em out but make sure you have a new hive readyand waiting at the bottom of the garden. THen when theyre all out, remove the old hive and destroy it.(after removing any XS honey)--Light current 09:53, 19 August 2006 (UTC)
- Hive + lighter fluid + matches = no more bees --Kurt Shaped Box 10:48, 19 August 2006 (UTC)
- ...or house. --Fastfission 12:40, 19 August 2006 (UTC)
- There is a nice recipe for napalm here. Shotgun shells can also destroy the hive. Hydrofluoric acid too. We could write a book! "99 ways to kill bees." — [Mac Davis] (talk)
- ...or house. --Fastfission 12:40, 19 August 2006 (UTC)
- What's wrong with having bees in the roof? --liquidGhoul 14:24, 19 August 2006 (UTC)
- BZZZZZZZZZZZ Yes I suppose theyll leave eventually and swarm to another hive--Light current 14:35, 19 August 2006 (UTC)
- I usually get them out of my house (attic) by creating smoke using charcoal tablet and olibanum then throw away the nest. They usually dont come back. helohe (talk) 15:50, 19 August 2006 (UTC)
Sheep and goat breeding
Hi
Does anyone know if sheep and goats have been bred together in the past to give the modern breeds of sheep and goat? I know that the sheep-goat hybrid page pretty much says it's impossible, but it'd be great if they have been.
Cheers
Aaadddaaammm 05:32, 19 August 2006 (UTC)
- Um no. but modern sheep are a mix of many breeds of sheep, though goats aren't as mixed. Still, they don't generally hybridise, they have different numbers of chromosomes. pschemp | talk 06:12, 19 August 2006 (UTC)
- True, but consider the strange case of "Bemya" the randy rapist sheep-goat. Rockpocket 06:39, 19 August 2006 (UTC)
- It aint randy no more -- apparently--Light current 06:57, 19 August 2006 (UTC)
Sea water turned Sweet
Hi,
This is regarding a Phenomenon which occured yesterday(18/08/2006) around 10 p.m. in one of the areas in Mumbai in India. One of the guys who was having a bath in the sea, accidentally drank the seawater and to his surprise it tasted sweet. And the news spread like anything and in hours thousands of people gathered at this place to collect the sweet sea water. People started drinking the water thinking it as a holy thing, forgetting the fact that it is highly contaminated by domestic sewage and industrial effluents. They all think without exception that it was a miracle that would cure them of every known ill on the planet.
So My question is why this happened? Were there any incidents similar to this occured ever before in any part of the world? what would be the scientific reason behind this?
If anybody can answer these questions it will be appreciated.
Thank You
- When you say sweet, do you mean not salty? If so, is it possible there had been a big outflow of fresh water into the sea at that point after heavy rains. Which part of Mumbai did this happen in. Is Mumbai near the mouth of a river?--Light current 06:48, 19 August 2006 (UTC)
- The're now confirming that it could be due to the heavy rains. And it is at the mouth of the Mithi River =Nichalp «Talk»= 17:14, 19 August 2006 (UTC)
- I'm from Mumbai and the incident happened near the dargah of Makhdoom Ali Mahimi in Mahim. People have been attributing it to miraculous powers but from my knowledge of the geology of Mumbai, the city is known to have many underground springs just metres away from the sea shore. Prominent examples are the Bhika Behram Well at Churchgate, the underground springs that used to feed the now-filled up Dhobitalao (the springs were rediscovered when the subway construction started last May) [I have a pic of them], Banganga Tank (50 m from the shoreline), and an underground stream that is used to water Priyadarshini Park. I'm discounting water sources in the suburbs as there are plenty of lakes and rivers. So I don't think it's a miracle. Regards, =Nichalp «Talk»= 08:38, 19 August 2006 (UTC)
- It would be interesting to see this scientifically proven, but I doubt it. Didn't terrorists bomb a sugar company yesterday? — [Mac Davis] (talk)
No glare using UV
Why is it that when illuminating paper thro a plastic sleeve by UV, you get no glare, but you get glare from the sleeve when using visible light?--Light current 07:37, 19 August 2006 (UTC)
- You can see the visible light that reflects off the plastic, but you can't see the UV light that reflects off because it's invisible UV. The only reason you can see the paper under UV is because the paper fluoresces, which means it absorbs UV and emits visible light. The plastic doesn't fluoresce because it's transparent and doesn't absorb the light. —Keenan Pepper 09:59, 19 August 2006 (UTC)
Of course! Why didnt I think of that? THanks alot! Any way it seems a good method of illuminating music to read without illuminating anything else! Not sure of any hazards tho!--Light current 10:02, 19 August 2006 (UTC)
- I hope you're not thinking of taking one right from a lab to use as reading lamp, probably not such a good idea, unless you mean one of these cheap novelty bulbs, they're pretty much harmless--71.247.125.144 13:29, 19 August 2006 (UTC)
Dunno havent researched it yet. But a musician friend if mine has made one. It uses a bulb shaped like a normal incandescent. Not sure where he got it but its not a germicidal one-- its probably a longer wavelength 'blacklight' bulb--Light current 14:33, 19 August 2006 (UTC)
- A minor note of caution—while there isn't much evidence (at this time) to support a link between long wave ultraviolet (from the 'black' lights) and skin cancer or cataracts, this type of UV is definitely energetic enough to damage collagen in the skin. This sort of damage is associated with premature aging and the formation of wrinkles. I'm not sure how much of a dose you'd get from one of those little lights, but it's something to bear in mind if you intend to sit in front of one for hours at a time. TenOfAllTrades(talk) 15:51, 19 August 2006 (UTC)
THis musician friend is about 75, so I dont think itll do him much harm. I.. OTOH, am much younger (and look it)--Light current 16:16, 19 August 2006 (UTC)
Where did the brain of the zygote/fetus come from?
Since we came into existence when the sperm hits the egg, it becomes a zygote! So the zygote developes into a fetus. Someone could say "I was a sperm once." Or, "I was an egg once," when someone else could say "No, you're really when the sperm and the egg hit to become a zygote."
Well, I really consider myself to be my brain, so I'm curios: Did the sperm have 1 hemisphere of the brain and the egg the other hemisphere, and the 2 brain hemispheres merged to become our current brain when the sperm hit the egg? (I'm thinking not, so I'm assuming maybe the brain, or what became of the brain, is 100% from either the sperm or the egg)... But which one? User:NealIRC 19 August 9:17 (UT)
- Half chromosomes from sperm, half chromosomes from egg I think. Chromosomes are only the instructions on how to build a baby so all your brain is due to both parents I would say.--Light current 09:13, 19 August 2006 (UTC)
- Light current is right; an initial cell is formed from the fusion of the sperm and the egg. That cell divides into many and differentiates into different structures, including the embryo and the placenta. The placenta also divides into many structures, one of which becomes the brain and spinal cord. You may find Fetal development an interesting article. If you're really keen, look at Neurulation, but that's rather a technical article.-gadfium 09:29, 19 August 2006 (UTC)
- My god! My guess was right! I must take up biology (or is it embryology)--Light current 09:38, 19 August 2006 (UTC)
- Well, it's a pretty straightforward conclusion, other than the details on how the development takes place. The sperm and the egg, being single-celled, have no brains whatsoever, and not even something that resembles a brain. Neither does the initial embryo. The brain develops much later. The instructions on how to build the brain, though, naturally come from both halves of the genetic code, as do most other things. Black Carrot 14:52, 19 August 2006 (UTC)
Symbols on electrical appliances
Some electrical appliances have symbols on them, like an inverted triangle with an F inside, or a circle with an S, N, or D, and other symbols. I looked for a site that explains what these symbols mean but surprisingly I couldn't find any. Maybe you can help. S Sepp 13:31, 19 August 2006 (UTC)
- The circle with the N inside means that it has been authorized for use in Norway. I would guess that the S and D work the same way for Sweden and Denmark, respectively. Have'nt seen the F in an inverted triangle. -N·Blue talk 14:16, 19 August 2006 (UTC)
- Agree. I think theyre all European underwriters approvals (like UL in US)--Light current 15:00, 19 August 2006 (UTC)
- Are the signs any thing like this? [13]
Which Glue in a Microwave-Convection Oven?
On cleaning my combination microwave-convection oven, I noticed that one of it's internal seals is cracked. The seal is an 120x100x0.3 mm mica plate covering the site of entry of the microwaves into the oven cavity, sited in the top wall (ceiling?) of the oven. Its function seems to be to prevent vapours from the oven from reaching the magnetron workings. The crack was probably caused during cleaning, and runs about halfway through the plate from one side to the other. The oven itself is a standard 900W microwave, and it has a convection heating element and fan situated in one of the side oven walls, with halogen grilling tubes in the ceiling. The convection temperature can be set up to 240°C. So the mica seal would be exposed to microwave energy coming through it into the oven, as well as to hot air, water vapour and hot oil droplets from the convection heating and the food. It would not be directly exposed to the infrared from the halogen tubes. My question is, can anyone suggest a bonding material which would keep the crack from spreading? It would have to be microwave-safe once cured, able to tolerate pretty hot, humid and oily conditions, and obviously not highly toxic. It need only last for as long as it takes to get a replacement seal, a week or two. Any ideas? --Seejyb 15:04, 19 August 2006 (UTC)
- Don't use cyanoacrylate or anything polyvinyl acetate. — [Mac Davis] (talk)
- What about a 2 part epoxy (like Araldite). I dont know the upper temp limit tho!--Light current 16:42, 19 August 2006 (UTC)
- I wouldn't recommend trying to fix it, especially if you are getting a replacement in the near future. Is there a functional reason that you can't operate the device without this sheild? If so, perhaps removing it and using a temporary shield of waxed cardboard (if you are worried about steam and spattering on the magnetron housing) would work.Tuckerekcut 17:34, 19 August 2006 (UTC)
Airplane's low oxygen
I was just watching on "Discoveries this Week", on The Science Channel flight attendants training. I wondered how long could somebody like Lance Armstrong or Greg LeMond with a VO2 max of 80-95 last in normal conditions of a plane losing pressure or oxygen concentration or whatever it was. Could they just sit there? If not, how long would it take? — [Mac Davis] (talk)
- If they were in a near vacuum, they might end up exploding. —Daniel (‽) 16:01, 19 August 2006 (UTC)
- Not really any more than diving two or three meters causes people to implode (also a 1 ATM pressure difference). See explosive decompression and the external link at the bottom of that article. Also on the subject: cabin pressurization, altitude sickness. How a person reacts depends on what he tries to do, what the pressure is (i.e. altitude), does he have time to acclimatise, ... Weregerbil 16:40, 19 August 2006 (UTC)
- I dont think thats quite right Weregerbil. I think the human body can stand more inward force that outward because the internal blood and fluid pressures can balance inward forces more easily. If you put a sucker on any part of your body ( 8-)) the blood pressure will tend to forse the tissues out and maybe rupture some blood vessels. Didnt yoo see that film Total Recall (Arnie Schwarzeneggar) and the bit where he was ejected onto the zero pressure surface of Mars. Nasty! --Light current 16:49, 19 August 2006 (UTC)
- Yeah, I saw Total Recall. Hollywood is unique in that it is the only place in the universe where people explode in vacuum. See explosive decompression and the external link at the bottom of that article. The external article in particular lists real world cases of people having been exposed to hard vacuum. Weregerbil 17:34, 19 August 2006 (UTC)
- Hey I wouldnt recommend it :
During this time, water vapor will form rapidly in the soft tissues and somewhat less rapidly in the venous blood. This evolution of water vapor will cause marked swelling of the body to perhaps twice its normal volume unless it is restrained by a pressure suit. (It has been demonstrated that a properly fitted elastic garment can entirely prevent ebullism at pressures as low as 15 mm Hg absolute [Webb, 1969, 1970].) Heart rate may rise initially, but will fall rapidly thereafter. Arterial blood pressure will also fall over a period of 30 to 60 seconds, while venous pressure rises due to distention of the venous system by gas and vapor. Venous pressure will meet or exceed arterial pressure within one minute. There will be virtually no effective circulation of blood. After an initial rush of gas from the lungs during decompression, gas and water vapor will continue to flow outward through the airways. This continual evaporation of water will cool the mouth and nose to near-freezing temperatures; the remainder of the body will also become cooled, but more slowly.
my bolding
From that ref of yours.
Complete replacement of cells
Hi all! I've tried as hard as I can to look for a Wikipedia article which talks about the time it takes for different types of organs and tissues to replace their cells completely with new ones (processes which I'm sure you've heard about, since people love saying that 'we all become completely new persons every X months' because of this...-.-), but I haven't been able to find anything remotely like that! (I don't know if this even has a name of some sort...)
I hope I'm clear about what I'm talking about: as far as I know, it takes a certain amount of time for, say, bones to replace all its old cells with new ones, and of course there are different time periods for different tissues to 'become completely new', from hours to months! (Not ALL tissues do this of course, but you'd be impressed by how many actually do!) I hope this subject isn't just spread around the articles for each organ or cell type, because this'd make for a pretty good and informative article all by itself!
I'd be grateful if you could point me to an article which talks about this, or simply check if there is indeed no article about this, so the right thing is done and it is written. Thanks in advance! Kreachure 17:10, 19 August 2006 (UTC)
Time measurement
I was working on an article related to time measurement (Indian Standard Time) before the advent of the atomic clock. The best information I could find on wikipedia is the article Tempometer. My question is: Before the atomic clock came into existence, how did people accurately measure the precise time? (I'm interested in the era between 1800 to 1955). Regards, =Nichalp «Talk»= 17:25, 19 August 2006 (UTC)
- Have you tried chronometer yet?--Light current 17:32, 19 August 2006 (UTC)
- Yes I did, and the best mention there was the H4 chronometer. I'm specifically looking for an official device (if any) that the governments used to keep the time. =Nichalp «Talk»= 17:43, 19 August 2006 (UTC)