Wikipedia:Reference desk/Archives/Science/2006 November 4

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[edit] November 4

[edit] Swallowing and breathing

I'm sure I read somewhere that the reason why we can't breathe and swallow at the same time is because we gave up that ability for the ability to talk. Is that so? And is there a Wikipedia article on it? Vitriol 00:12, 4 November 2006 (UTC)

And by "gave up that ability" I meant it was more advantageous to be able to make more complicated vocalisations than to be able to breathe and swallow, so all the breathe-and-swallowers died out yadda yadda yadda you know this by now. Vitriol 00:17, 4 November 2006 (UTC)
Im sure I saw somewhere (on TV?) that the human larynx had descended, making it poossible to talk and breathe, swallow etc but not necessarily at the same time

Quote from our page:

Some linguists have suggested that the descended larynx, by extending the length of the vocal tract and thereby increasing the variety of sounds humans could produce, was a critical element in the development of speech and language. Others cite the presence of descended larynges in non-linguistic animals, as well as the ubiquity of nonverbal communication and language among humans, as counterevidence against this claim.

8-)--Light current 00:51, 4 November 2006 (UTC)

It's nice to have backup :D Vitriol 00:53, 4 November 2006 (UTC)
That last bit doesn't answer my question though. Vitriol 01:05, 4 November 2006 (UTC)
Didnt you look up larynx?--Light current 01:08, 4 November 2006 (UTC)

I don't see how it would ever have been possible to breathe and drink at the same time, if it all comes down the same esophagus. How would you separate out the air to be sent to the lungs and the water to be sent to the stomach ? StuRat 01:11, 4 November 2006 (UTC)

Some vents do it!--Light current 01:13, 4 November 2006 (UTC)
I don't know. That's why I'm asking you people. Vitriol 01:21, 4 November 2006 (UTC)
Actually, I've got all I care about from the larynx article. I figure it would be mentioned in articles about speech and things, but I was wrong, I guess. Vitriol 01:23, 4 November 2006 (UTC)
OK if you think so, why not add some links to those articles? 8-)

[edit] GE

1) Is genetic engineering able to cure cystic fibrosis and types of cancer now?

We're working on it. Possibly. And not us specifically. Vitriol 00:39, 4 November 2006 (UTC)

2) What are the risks through eating genetically engineered food.

I wouldn't think there would be any, considering the DNA in our food is obliterated before it enters us and even if it wasn't, it wouldn't do anything. I can only think of allergic reactions and such. Vitriol 00:52, 4 November 2006 (UTC)

Fairly minimal, but there are some:

  • The genetically modified plants could "escape", and outcompete natural plants to extinction. This could leave us with a monocultural plant, with the same inherent susceptibility to disease, much like what has happened, without genetic engineering, for the Cavendish banana.
  • If those doing the genetic engineering only focus on attributes which make the food sell, like apples being bright red, at the expense of their nutritional value, this could have a negative effect on nutrition.
  • Disease and insect resistant plants will put pressure on those organisms to overcome that resistance, which could then wipe out plants which lack this protection.

StuRat 01:01, 4 November 2006 (UTC)

3) Then is there any risks for genetic engineering itself?

Sure, genetic engineering on humans carries huge risks as well as benefits. Genetic engineering on bacteria and viruses could create deadly bioweapons, potentially racially targeted. StuRat 01:04, 4 November 2006 (UTC)
I have heard that gene therapy has been used to cure cystic fybrosis, but it has to be done in the womb, as you have to affect the cells a few layer below the lung surface, and that is impossible, with current technology, in adults as there are too many cells, and it would severely damage the lung (what a long sentence!). Quite a few of those patients treated, ended up having leukaemia as well, so it is obviously in very early stages. --liquidGhoul 01:43, 4 November 2006 (UTC)

[edit] Hydrocarbon compounds

My science teacher was telling me that in theory you could make chains of as many carbon and hydrogen atoms combined as you want as long as they're all stable. Unfortunately he could only remember the first, methane (CH4). The wiki article on hydrocarbon lists up to four carbons, butane (C4H10). What is currently the longest named Hydrocarbon chain? --The Dark Side 01:57, 4 November 2006 (UTC)

Simple hydrocarbon chains (single carbon bonds like C4H10) are called alkanes. I'm not sure what the longest one created is. The article should have some information on what happens as the chain lengthens such as changes from gas to liquid to solid at room temperature.--Tbeatty 02:15, 4 November 2006 (UTC)
OOh. List of alkanes goes up to 100. --Tbeatty 02:18, 4 November 2006 (UTC)
100? pffft. what you want is ultra high molecular weight polyethylene (UHMWPE). it is a straight alkane chain, between 200,000 and 500,000 carbons in length. while methane is good for cooker fuel, UHMWPE makes a great bulletproof vest (aka Spectra in this application). shows you what a few orders of magnitude can do. Xcomradex 05:31, 4 November 2006 (UTC)
The longest alkane with a pseudo-greek name would be nonalianonactanonacontanonane (say that ten times fast!) which would be C9999H20000. The reason being that the IUPAC nomenclature only gives multiplying prefixes up to 9000. In practice noone uses that kind of nomenclature for any chain longer than 20 carbons though. (You'd probably be accused of obscurantism if you tried.) In theory, at absolute zero, you could actually make a hydrocarbon chain infinitely long (as long as you have enough stuff). But in practice, where you can't actually get to absolute zero, there's a theoretical upper limit on how long you can make the chain due to entropy. That is, the higher the temperature and the longer the chain, the less stable it is. (Come to think of it, it'd be interesting to try and estimate that length at room temp) --BluePlatypus 22:54, 4 November 2006 (UTC)
Wouldn't that be wrong if you followed the IUPAC rules because there's 20000 Hydrogen, 11000 more then allowed? --The Dark Side 00:08, 7 November 2006 (UTC)

[edit] Black Hole characteristics

Besides within the event horizon itself where I might find actual values (to avoid any such response) where can I find a list of the values for temperature, heat (either latent or sensible) volume, pressure, speed of light, distance (diameter) and other such physic characteristics that are presumed to exist within the event horizon of a Black Hole? Adaptron 03:06, 4 November 2006 (UTC)

Black holes don't have any of those characteristics. See No hair theorem. —Keenan Pepper 05:03, 4 November 2006 (UTC)
Except for diameter and volume. Those are infinitely small; black holes are gravitational singularities. Of course, since no information can escape from black holes, this doesn't matter for anybody outside the black hole's event horizon. --Bowlhover 06:16, 4 November 2006 (UTC)
Well, the event horizon is basically the point beyond which no information can escape. However, things passing through the event horizon won't notice, so gas falling in towards the black hole will still possess whatever characteristics it had when it passed through the horizon (for some time, until all sorts of interesting QM effects start happening when it falls in far enough). Virogtheconq 06:28, 4 November 2006 (UTC)
They may have those characteristics-- its just that you cant tell what thay are from outside the event horizon. For example we may be inside a very large black hole, yet we can measure things!--Light current 21:15, 4 November 2006 (UTC)
The speed of light should be the same within and outside the event horizon. — Knowledge Seeker দ 21:30, 4 November 2006 (UTC)
It is. But it would be red shifted if it tried it get out. It just doesnt have enough energy.--Light current 09:29, 5 November 2006 (UTC)

[edit] Bacteria.

1)What is your name? 2)What is your title on bacteria scientology? 3)What is bacteria in your opinion? 4)How does bacteria develop? 5)How should people with bacteria growing in their household take care of it? 6)What are the effects of ultra-violet light on bacteria growth?

Thank You.

Hmm, the Reference Desk isn't really a place to conduct internet interviews, I'm afraid. Try the article on bacteria. BenC7 03:32, 4 November 2006 (UTC)
It is years since some one asked me the questions in my Medical College during my II Clinical Practicals  Doctor Bruno  13:58, 4 November 2006 (UTC)
1) My name Jose Jimanez.
2) My favorite title on bacteria scientology is Tom Cruise: Coliform Pathogen or Vapid Proselytizer?.
3) What is bacteria in your opinion? In my opinion, bacteria is God's way of recycling really old men.
4) How does bacteria develop? Bacteria works out in Gold's Gym three times a week and eats very healthy food.
5) How should people with bacteria growing in their household take care of it? Bacteria will thrive on table scraps and a few affectionate words. It's easy to care for and will reward your attention with years of companionship.
6)What are the effects of ultra-violet light on bacteria growth? Bacteria should try to avoid discotechs and other places they might encounter ultra-violet light. Bacteria should also avoid second-hand smoke, which might also stunt their growth. - TraumaMama 03:30, 4 November 2006 (UTC)
That's Jose Jimenez. Clarityfiend 04:38, 4 November 2006 (UTC)
If you have to do an interview on bacteria, maybe you can contact a professor at a local community college or a high school science teacher. You could also talk to some sort of medical professional, but they might be too busy. Their email addresses are probably available at the websites of the institutions where they work, and you can probably call the school as well and find a good time to meet them. When you do contact them, don't just jump into the interview, introduce yourself first, tell them you're doing a brief interview for your class, and then ask questions.
Also, I noticed you used the term "scientology". That's a religion, you're looking for a word like "science" or "microbiology". You might ask "What experience do you have in the scientific study of bacteria?" or "What experience do you have in cell science?". Good luck, and I hope this helps you. Gary 13:00, 7 November 2006 (UTC)

[edit] Water

Two quesitons. 1) What is the significance, in the scheme of things, that water has a relatively high melting and boiling temperature? I thought that perhaps if the melting point was lower (colder), there would be less polar ice and therefore less land. But life would still be around. Any other ideas?

2) I currently have written, "Most life on earth is in the oceans", but I suppose that would depend on how it is measured (I seem to remember reading it somewhere...) So, how can I rephrase this statement to make it more accurate? (e.g., "If measured by amount of biomass, most life on earth is in the oceans", or "If measured by number of species...") If it is not true by any measure, I can always say "A large portion of life on earth is aquatic..." but then I would probably want to say approximately how big that portion is. BenC7 03:41, 4 November 2006 (UTC)

It would have an effect on beings that are made up of water, like humans. Certainly if the boiling point was lower, like 100F, we'd be in deep trouble if we get a fever that high. --Wirbelwindヴィルヴェルヴィント (talk) 04:10, 4 November 2006 (UTC)
But if the boiling point of water was lower, life would have evolved to adapt to that lower boiling point. I agree with StuRat's answer (below)--the water cycle must keep going at a fast pace in order to deliver water to most of the world's land. Earth, of course, has the perfect temperature for that to happen.--Bowlhover 06:05, 4 November 2006 (UTC)

A wide range of temps at which liquid water can exist is important to life on Earth. And, of course, that range must correspond with the actual surface temps on Earth. StuRat 04:31, 4 November 2006 (UTC)

Someone once told me that if the freeze/boil points of water were any different life would have never evolved on a planet of this temperature. Evaporation and precipitation rates are extremely important to how the ecosystem works and are tied in with the boiling/freeze points. A slightly related fictional work is called Ice 9. ---J.S (t|c) 05:59, 4 November 2006 (UTC)

I don't know the significance of having both solid and liquid water available, but I do know that one of the unique characteristics of water is that it expands when it freezes, so frozen water will float to the top of the liquid, which cycles it around and prevents the formation of a large solid mass at the bottom of the ocean. Virogtheconq 06:09, 4 November 2006 (UTC)

  • It's not actually unique; there are quite a few substances that expand on freezing. Water is just the only one that occurs commonly and where this property is so important to us. Others include bismuth (where this property was taken advantage of in hot metal typography) and antimony. --Anon, 11:38 UTC, November 4.
True. Perhaps I should have said "distinguishing" characteristics. However, water is also composed entirely of elements that are readily available from nuclear reactions and has a simple structure, so it's the most likely candidate via Occam's razor (not that the razor is really means much...). Virogtheconq 15:22, 4 November 2006 (UTC)
If ice is denser than water, having a giant slab of ice at the bottom of the ocean wouldn't be the main problem. The main problem is that, with nothing to protect the water after the ice above it sinks, the water would freeze, sink, expose the water below it..and the whole ocean would freeze. --Bowlhover 06:28, 4 November 2006 (UTC)
Well, that's what I meant. It's been a long day =O). From my limited recollection of the last time I studied bio, I think there are several other liquids that have the same properties as water (such as ammonia) but for the expanding as a solid - so conceivably life could exist in environments with little water, but they'd have to be in a very unique environment that has mechanics for cycling frozen material to warmer locations.
Or, the planet's temperature could always stay above the material's freezing point. Liquid ammonia...tasty... --Bowlhover 10:30, 4 November 2006 (UTC)
Well, I was considering that initially, but even if the surface temperature was over the freezing point, one still has to consider what the temperature would be like at the bottom of an ocean. But yes, generally there would at least be standing puddles to splash around in. Virogtheconq 15:20, 4 November 2006 (UTC)

[edit] Ears ringing

Hey guys, just wondering if my ears were normal. Every time I put ear plugs in my ears, I hear them ringing. Even with the silicon ones that just cover your ear-hole, is this normal? Is anyone else like this? Thanks

Doesnt sound normal to me. Maybe you have some hearing damage. See doctor.--Light current 09:54, 4 November 2006 (UTC)
Too many loud concerts? Tinnitus comes in all degrees; if worsening, see an ENT doc. alteripse 11:37, 4 November 2006 (UTC)
Consult an ENT doctor and get some investigations done  Doctor Bruno  14:00, 4 November 2006 (UTC)
It's quite possible that the ringing is present at all times, there's just usually too much background noise to hear it. It could be age-related, it could be too much loud music or too much traffic/workplace noise, it could be an early symptom of a more serious problem. As for almost any medical question, the best advice we can give you is to tell you to seek the advice of a physician. TenOfAllTrades(talk) 14:47, 4 November 2006 (UTC)

Do you regularly take aspirin or a med containing aspirin ? That is a known side effect. StuRat 15:28, 4 November 2006 (UTC)

To be honest, I've had the same thing since at least 12 years of age (my memory is hazy earlier). It causes me to have to listen to the radio at night. I've been told that it's not a very serious thing, and my hearing is fine, but I havn't specifically gone to any doctors about it. I have to echo the others though, we're not a reliable source of medical advice. -- Consumed Crustacean (talk) 09:41, 5 November 2006 (UTC)

[edit] six pack

howcome one side of six pack is recognisable and the other is fatter and i can't see anything except a big lump. is there anyway to solve this problem?

When you say six pack, do you mean a muscley front of a person? Do you mean a six-pack of beer? Or something else? At the moment, it's hard to know what you're asking. Skittle 15:11, 4 November 2006 (UTC)
One side contains your liver. It could be large.--Light current 15:32, 4 November 2006 (UTC)
If you drink half your six pack, one side may appear larger than the other, depending on which cans you selected. I pull beers from my six pack in such a way that it is still as balanced as possible and therefore easier to carry. So the problem is in which cans you are selecting from your six pack. Remember that drinking six packs can create a "beer belly" that hides the abdominal muscles. --Ginkgo100 talk · e@ 15:55, 4 November 2006 (UTC)
I fear we are now at the point of divergence! 8-)

--Light current 16:10, 4 November 2006 (UTC)

i mean muscly front of a person

You could be a mutant. How big is the lump? conjoined twin maybe? Vespine 00:45, 6 November 2006 (UTC)
Are you in pain? Is this a new occurence? You could have a hernia, though I believe they are usually quite painful. You need to ask a doctor, in either case, as medical advice (of any sort) is a bad thing to try and get online. Failing that, you should probably at least have a friend or a parent look at it. Dina 23:45, 6 November 2006 (UTC)
Since we're all speculating here, you might have a slight spine curvature that makes it difficult to work out both sets of ab muscles equally - the "cut" side is doing all the work while the flabby side is just hanging out. See a doctor. -sthomson 16:10, 7 November 2006 (UTC)

[edit] Intensity dependent dye effect

Have any studies been done on what actually causes the intensity dependent dye effect which causes the curve in MA plots from microarray data? Aaadddaaammm 08:01, 4 November 2006 (UTC)

[edit] How much land required to keep free-roaming peacocks?

I dream of being wealthy enough to own a house and garden large enough to keep peacocks. Does anyone know how much land I would need please? Land is expensive in the UK. I suppose part of the problem may be being far enough from neighbours so that they are not disturbed by the noise.

There look to be some useful links at the end of our peafowl article. I think food supply would be more critical than the amount of land, as you will need to feed them anyway. And it would need to be in a sheltered area.--Shantavira 10:50, 4 November 2006 (UTC)
A cock peacock's yell is rather quieter than the yell of a hoodie, so if you can't hear the neighbours or the street from the house, they probably won't hear the peacocks - but that does mean a proper country house with grounds; there's really no urban setting where they aren't going to rile the neighbours. And beware the peacocks' bad habits and objectionable personalities - those that live at Dunfermline Abbey habitually march around on the street outside, causing traffic jams when they stop in the middle of the road to yell at motorists. And I'd worry about keeping (rather expensive) peacocks in the countryside too - country folk still have that Hugh Fearnley-Whittingstall philosophy, so your noisy bad-tempered avian geegaws are likely to end up in someone's pie. -- Finlay McWalter | Talk 10:50, 4 November 2006 (UTC)


[edit] What does roast seagull taste like?

I live on the coast and I often see turkey-sized seagulls walking about. Its going to be Christmas in one or two months time so my thoughts turn to wondering to what roast seagull would taste like?

As they often feed at rubbish dumps, they will probably be infected with salmonella, but so are some chickens. Also, killing a free living bird many be no more unethical than putting a battery-chicken or unlit-barn turkey out of its misery.

As I understand it, gull meat is dark, tough and greasy. There's not as much meat on them as it would appear either - they have very thick feathers and puff themselves up. --Kurt Shaped Box 10:51, 4 November 2006 (UTC)
If they were edible, people would be eating them. Why not try a nut roast this Christmas?--Shantavira 10:53, 4 November 2006 (UTC)
AFAIK, they do eat gull in parts of Scandinavia. In the really cold, desolate parts. Where it's really isolated. Where there's little else to eat meat-wise before they have to resort to the gulls. --Kurt Shaped Box 11:34, 4 November 2006 (UTC)
I don't think so, or at least haven't ever heard of it, despite having lived there. But you can get a Puffin pizza in Iceland if you want. But that's a different and presumably better-tasting seabird. --BluePlatypus 22:25, 4 November 2006 (UTC)
I remember seeing an interview with an Icelandic footballer on TV a while back in which he was showing the journalist round his new home in England. In his kitchen, he had a big packet of whole, dried, salted puffins that he'd had shipped over. --Kurt Shaped Box 22:32, 4 November 2006 (UTC)

Sharks, alligators and crocodiles on most of the nature shows seem to like them uncooked. Adaptron 11:55, 4 November 2006 (UTC)

Hmmm Is it legal where you are? Heh. I always considered that to be Poaching, but I hold gulls in high respect. Oh, and I heard they eat it in Misilise for christmas dinner, but that may have be a joke. --Jack, the freak without the user

Well I guess no matter how bad gulls are, they can't be that much worse then turkeys can they? Nil Einne 15:52, 7 November 2006 (UTC)

[edit] Spinning (rotating) Black Hole

Can a Balck Hole spin fast enough to change the location (radius) of its event horizon? Adaptron 11:49, 4 November 2006 (UTC)

Yes I believe spinning does alter the shape of the event horizon significantly.--Light current 14:35, 4 November 2006 (UTC)
Rotating black hole probably has what you're looking for. Actually, more than probably. =O) Virogtheconq 15:25, 4 November 2006 (UTC)
Not only that, but it also changes the singularity in the middle from a point to a ring, as well as a few other cool effects (as probably explained in the above-linked article). Confusing Manifestation 01:56, 5 November 2006 (UTC)

[edit] thermometer thingy

hello i was hoping you could tell me about this thermometer thingy my friend got it seems to have simler qualites to the gallilao thermometer it is glass and has a bulb at each end and a curly whirly tube that connects them a blue or green (cant remmber exactly) liquid in one bulb when you put your hand arround the bulb the coloured liquid quickly shootst round the curly whirly glass tube up to the top or down to the bottom its rely cool. i would be well chuffed if you could find out for me thanks

It sounds like a novelty mercury thermometer to me, where they added dye to the mercury and put it in a spiral shaped tube. It the liquid is mercury it will be opaque. If you can see through it, then it's something else. StuRat 15:04, 4 November 2006 (UTC)
I think I know what you're talking about - it's one of those novelty items that's sometimes sold as a love tester or somesuch. It can function to a very limited degree as a thermometer, but it's mostly designed so the temperature of the human body (98 F) will raise the temperature of the held bulb (usually the lower one, but the process can be reversed by holding the upper one) will completely force all the fluid from the held one to the other bulb. It's been years since I've seen one of them, so my knowledge of how they function is a little shaky. I'm guessing there's probably an alcohol or some other volatile fluid inside the bulb. Virogtheconq
Could it be a volitile fluid at reduced pressure, to make it boil at body temperature? Edison 02:49, 5 November 2006 (UTC)

[edit] abortion again

i had posted a question about abortion earlier on.the abortion was done 4 weeks ago.and what the hell is a d and c?the body i doin well she has no pains she is as fit as a fiddle her periods just havent not yet come.who has an answer....please

See abortion . D and C is something to do with cleaning out the uterus I believe--Light current 15:29, 4 November 2006 (UTC)

Did she have regular periods before she became pregnant. What is her age. What is the age of Menarche. If you feel the answer to the above questions will be personal, you can contact by Mail Such facts are needed before I can give a proper advice. Or if you can give the details here, I can reply here itself  Doctor Bruno  16:06, 5 November 2006 (UTC)
Out of interest, did you ever get contacted? Nil Einne 10:38, 7 November 2006 (UTC)

[edit] Reaction Rate Constant

I'm having difficulty calculating reaction rate constants for first-order reactions. Any help would be appreciated. Thanks! -- Sturgeonman 17:10, 4 November 2006 (UTC)

what data do you have? i'm assuming you have a series of rates, at a series of concentrations, and a rate law, or a means to find one. for a simple unimolecular first order reaction A->B, the rate law is:

rate= -k[A] or k[B]

so you can simply rearrange the equation to give the rate constant k, then solve at a given rate and concentration. got it? Xcomradex 01:27, 5 November 2006 (UTC)

Thank you! I get it. It seemed extremely complex on the article page; I guess I just overlooked rearranging the equation. Sturgeonman 19:35, 5 November 2006 (UTC)

[edit] Measuring outside temp in cars

How is the outside temp measured in cars? And where do they put the sensor?--Light current 17:30, 4 November 2006 (UTC)

In my vehicle (Chevy Avalanche), the sensor is on the roof, right above the display unit, which is in front of the rear view mirror. This location gets a nice breeze while driving so gives an accurate outside temp reading at that time. However, while idling, heat from the engine comes out from under the cowl, follows the windshield up, and heats the sensor. I've had temp readings of 110 F while idling on a nice cool day. StuRat 19:44, 4 November 2006 (UTC)
Yeah thats just the sort of thing Im getting at: How accurate are these readings? If in bright sunlight or near the engine compartment, they may give a totally false reading. Im not sure if you could get the opposite (chilling) effect from the air flow when travelling fast.--Light current 20:18, 4 November 2006 (UTC)--Light current 20:18, 4 November 2006 (UTC)
Well typically they'd measure it the conventional way, with a thermistor. The location is an interesting question. I'd assumed they'd put it in a good place, which I'd assumed would be in some nook in the chassis, out of the way from wind and sunlight but as close to the road as possible. After looking into some auto manuals, that doesn't seem to be the case though, and it varies with the manufacturer. I guess that's to be expected, since it's not a priority thing there are probably a few thousand more important design considerations that need to be adressed first. Anyway, it seems that behind the grille but in front of the radiator is a popular spot, or under/behind the bumper, or around the headlights or rear-view mirrors. But it seems a bad location doesn't automatically translate into a bad value though, since it seems they now have some logic circuits connected to the things nowadays. So wind chill may not be a problem, since they can calibrate the thing to compensate for it in software. --BluePlatypus 22:01, 4 November 2006 (UTC)
Do you really think theyd use a thermistor? I designed a thermistor temp sensor once. Had to use a logarithmic amplifier to linearise the bastard!--Light current 22:26, 4 November 2006 (UTC)
Probably they would use a characteristic look-up table with the on-board computer. Then they just need the A/D with enough range. Tbeatty 02:48, 5 November 2006 (UTC)
Non-living things don't experience wind chill. I put a thermometer on my vehicle once, and it always read incorrectly. I experimented with locating the sensor in several locations: Behind the grill, under the bumper, at the bottom of the door seam. I always got falsely high readings after driving for some distance. Had the wire connecting the sensor to the display been long enough I would have put it on top of the radio antenna to see if that would get it out of the bubble of warm air coming from the engine. 192.168.1.1 3:05, 4 November 2006 (PST)
Are you sure you would not get a chill effect on a sensor dissipating power from a stream of fast moving air? Blow on some hot food -- does it not cool down? --Light current 00:36, 5 November 2006 (UTC)
Then the food reaches room temperature quicker but it doesn't cool below that. Wind should actually improve the accuracy of the sensor. My question is what happens when it rains. Is evaporative cooling during a rainstorm negligible because the RH is 100%? Tbeatty 02:48, 5 November 2006 (UTC)
(after edit conflict) Humans feel colder on a windy day because the wind takes heat away from the skin more quickly than if there was no wind. (Human skin is at 36 degrees. The colder the temperature, the quicker heat escapes from the skin. Wind helps the heat escape quicker.) However, the wind will never cool anything to below its own temperature. So if you blow on soup, you'll get it down to 36 degrees very quickly, whereas if you leave it alone, it will cool to 20 degrees slowly.
Tbeatty: if it rains, the thermometer will never cool down to below the air's temperature (or the rain's temperature, whichever is colder). We feel cold when water evaporates from our skin because water is a better heat conductor than air, and therefore helps heat to escape more rapidly. --Bowlhover 03:01, 5 November 2006 (UTC)
Actually he is sure. Strange as it sounds, because we humans are SO used to it, it is a very common misconception that moving air 'cools things down'. What you feel on your skin when there is a breeze on a warm day is the effect of evaporation, and blowing on somethng HOT will only cool it down to the temperature of the air. Air, no matter how fast it is moving, can only 'cool' something down until it is the same temperature as the air it self. In fact, air moving very fast heats things up. A simple test you can do if you have a thermometer and a fan, is measure the temperature then put the fan on the thermometer and you should see that it makes no difference. Vespine 01:04, 5 November 2006 (UTC)
Read my last post again. Also Im afraid you ignore the effect of evaporation cooling--Light current 01:07, 5 November 2006 (UTC)
Wind will cool things above the ambient temperature faster as it carries the heat away more efficiently. Open the hood on your car and you will see a fan that cools the engine. Evaportaive cooling is also effective for humans but on a car sensor, it would have to be raining to get the moisture. My question: is evaporative cooling negligible with it's raining (relative humidity is 100%)? I would think more of a factor of a rainstorm is that the water started 10,000 feet above the car and simply is colder than the ambient temoerature. --Tbeatty 02:52, 5 November 2006 (UTC)

The problem with most non-scientific temperature measurements is that they get exposed to direct sunlight, and are therefore typically higher temperatures than the air temperature you're used to seeing in meteorological reports. Meteorological thermometers are shielded from direct sunlight, with the classic example being the cotton region shelter. I imagine it would be difficult, if not impossible, to design an automobile thermometer that would display great, accurate readings. EWS23 (Leave me a message!) 06:20, 5 November 2006 (UTC)

Let me clarify this discussion a bit:
  • Wind-chill does have an effect on both living and nonliving things, cooling them more quickly to the ambient temperature (or warming them to the ambient temperature) than they would without any wind. However, this form of cooling does not cool anything beyond the ambient temperature.
  • Evaporative cooling also has an effect on living and nonliving things, but, unlike windchill, has the potential to cool the object below the ambient temperature. This form of cooling requires that the object be moist and the humidity be below 100%.
StuRat 06:58, 5 November 2006 (UTC)
Just to throw my .02 in, on Hondas the sensor is placed in the front air dam, out of direct sunlight and somewhat out of the way of heat from the engine. It is quite accurate to ambient temperatures and only heats excessively when in heavy traffic and road temps are noticeably climbing. The thing about evaporative cooling (which you guys eventually got right) is that the object has to be WET in an otherwise DRY environment. This is not likely to happen all that often in the real world, unless (for example) you splash a puddle onto the sensor on a dry day. In that case, you would probably see a minor shift in temperature but it would be very brief since most of the water will be blown off the sensor before evaporating, and since there is a good chance the water isn't exactly at air temp anyway you had better just throw out all the data when that happens ;-) --Jmeden2000 16:25, 6 November 2006 (UTC)

[edit] worms

What did worms evolve from ?--Crocadog 18:07, 4 November 2006 (UTC)crocadog

These animals are so old (Precambrian) and soft we are not sure, but much is discussed in the annelid article. X [Mac Davis] (SUPERDESK|Help me improve) 19:14, 4 November 2006 (UTC)
Single cell amoebas just like everything else :).--Tbeatty 07:23, 5 November 2006 (UTC)

[edit] jellyfish

and whare did cindrians(jellyfish)evolve from?User:Crocadog 18:53, 4 November 2006 (UTC)crocadog

amoeba? Vespine 00:54, 5 November 2006 (UTC)
It's not correct to say either of these things (worms or jellyfish) evolved from amoebae. However given you are probably using the term 'amoeba' as a generic term for single celled Eukaryotes the answer is reasonable enough, with the Eukaryotes themselves evolving from Prokaryotes. Sadly the fossil record of the evolution of these creatures is remarkably poor for a number of reasons, most importantly that it was so long ago and fossils are very rare, and that soft body parts don't fossilise well (and these animals are all soft body parts). The fact that it was so long ago, and remember we're talking in the range of 600 million years, also makes it a lot harder to track their evolution using DNA evidence. --jjron 13:49, 5 November 2006 (UTC)

[edit] Polymers and solubility

Image:Fuvest732005.gif

(I´m not a native English speaker, so forgive any mistakes, or at least correct them please!) There´s a disposable diaper which is made of a polymer. The diaper can absorb a huge amount of water by osmosis, in which the semipermeable membrane is the polymer itself. For some reason, the appropriate polymer is the one at the top right corner of this image. Why is that? I´m not COMPLETELY ignorant on these subjects, I know fluorine is electronegative, and that can cause a molecule with fluorine to be polar, and I know polar things are soluble on polar things (like water), but doesn´t the symmetry of this polymer make the total polarity of the molecule zero? Wouldn´t the one with the chlorine be better for such a diaper?A.Z. 18:30, 4 November 2006 (UTC)

Well, the appropriate polymer isn't the one at the top right of the image. Your textbook/professor/other source is in error. You are correct; polytetrafluoroethylene (politetrafluoroetileno, trade name Teflon) does not absorb water. It is nonpolar and very inert.
To drive osmosis, you need to have a solute in solution. (Water will move from the solution with lower osmolality to the one with higher osmolality.) Only one of those five polymers pictured will produce an aqueous solute. Note that it is not the polyvinyl chloride (poli(cloreto de vinila)) that you've suggested. I'll leave it to you to work out which one it is. TenOfAllTrades(talk) 19:07, 4 November 2006 (UTC)
I see. It´s in fact the sodium polyacrylate, which is a (carboxylic acid and sodium) salt and therefore is an ionic substance, which is more polar than the one with the chlorine. I think I got it. Thanks! A.Z. 19:35, 4 November 2006 (UTC) It looks like I hadn´t got it, after all. You said only one of those will produce an aqueous solute. So, the polyvinyl chloride doesn´t become ionic in water. A.Z. 19:42, 4 November 2006 (UTC)
no it doesn't, but you have got it (its the sodium polyacrylate). think of it terms of the monomers, if you put ethyl chloride into water the last thing you'd expect to see is an ethyl+ ion. because alkyl halides are strongly covalent, rather than ionic. exactly why the you wouldn't expect to see the C2H24+ ion from dissolving tetrafluoroethane in water either. so the polyacrylate salt is the only one with a permenant charge, and therefore the most polar. Xcomradex 01:20, 5 November 2006 (UTC)

[edit] Magnetic field on light ray

Can a strong magnetic field bend a light ray?132.231.54.1 19:52, 4 November 2006 (UTC)

No, because magnetic fields can only affect charged particles (like electrons and protons). Photons are neutral; i.e. they have no charge. --Bowlhover 20:41, 4 November 2006 (UTC)
Bowlhover is correct about magnetic fields, but a very strong gravitational field can bend light beams a small amount. This is a common way to observe black holes. 48v 20:50, 4 November 2006 (UTC)
A black hole can bend light by any amount, but once the light bends enough it'll fall in, so we can't see it. But gravity does not actually bend light; the light still travels in a straight line. It's space itself that's been curved. But to an outside observer, it looks like the light is bending. Cute, eh? --BluePlatypus 21:21, 4 November 2006 (UTC)
All matter "bends" light just as it alters the course of any object. E=mc^2=hν gives light the mass it needs to interact with any object according to classical F = g(m1m2)/r^2. And as a technicality, the light path isn't bent by gravity, rather the space is manipulated by gravity so that a straight line in 4 spacial dimensions looks like the classical conical sections of 2 body interactions. Tbeatty 02:36, 5 November 2006 (UTC)
No. E=mc^2 does not give light any mass at all, it cannot be equated with the photon energy. Nor can you insert the result from E=mc^2 into Newton's equation. These are well-known mistakes, see for instance the Physics FAQ and the even more detailed article by Lev Okun that they mention. --BluePlatypus 07:42, 5 November 2006 (UTC)
Is there something else (besides matter, of course) that can bend a light ray?132.231.54.1 22:27, 4 November 2006 (UTC)
Besides matter, gravity, and the electromagnetic field, there are no other macroscopic phenomena known to science. So, there isn't "something else"... at all! Melchoir 22:37, 4 November 2006 (UTC)
And don't forget about plain old light refraction. StuRat 06:47, 5 November 2006 (UTC)
Lenses bend light of course, but as the above pointed out, they are made of matter ;).. Gravity lens is a great article. Vespine 00:49, 5 November 2006 (UTC)
POV 8-)--Light current 00:50, 5 November 2006 (UTC)
Technically, in the case of a Reissner-Nordström black hole, the electric charge contributes to the metric and thus the bending of light. And, since a magnetic field is just an electric field under a change of reference frame, you could say that the magnetic field bends the light! Confusing Manifestation 01:54, 5 November 2006 (UTC)


Magneto-optic effect? ≈Eh-Steve 02:05, 5 November 2006 (UTC)

See also Faraday effect, a slightly different phenomenon in wich a magnetic field rotates the plane of polarization of light. Edison 02:55, 5 November 2006 (UTC)

That's not entirely correct. Those magneto-optic effects are not the result of the magnetic field on the light, but rather the magnetic field on the medium through which the light is traveling. In a vacuum a magnetic field will not effect light at all; however, when light is going through something other than vacuum, it's possible for an applied magnetic field to change the optical properties of that material so that the light ray bends (birefringence might be another good article to look at). Virogtheconq 23:08, 5 November 2006 (UTC)
It's also used for isolation of transmit and receive ports on microwave radar (and radios) so the same antenna can be attached to a transmitter and receiver. It's called a circulator when used for this purpose. --Tbeatty 07:19, 5 November 2006 (UTC)

[edit] Rhubarb

what is the botanical and pharmacological description of rhuburb herb

See rhubarb--Light current 20:21, 4 November 2006 (UTC)

Since when has rhubarb been a herb? GeeJo (t)⁄(c) • 16:10, 5 November 2006 (UTC)
Actually the better question is, since when has it been a food. According to the rhubarb article, 400 years ago. Before then, it was a medicinal plant in Chinese health. Anchoress 16:17, 5 November 2006 (UTC)

[edit] Preventing menstrual cycle

I've heard that there are medicines that can prevent menstrual cycle in women without having very serious side effect. Is there such a medicine? And if so can you give me a name or a link to it? 81.178.122.199 20:36, 4 November 2006 (UTC)

I don't know about 'various', but there is a new birth control pill that allows women to go for months without a period. Of course the Pill is a prescription drug, so you'd need to go see a doctor anyway, so you may as well contact your doctor or a Planned Parenthood clinic to get more information. But HERE'S an article about the drug to get you started. Anchoress 21:16, 4 November 2006 (UTC)
See our Seasonale article for one brand of pill that allows a menstrual period only once every three months. But it is essentially an "on label" packaging of the same "off label" method described below and used by many women for years: Simply skip the placebo week.
Atlant 00:30, 5 November 2006 (UTC)

There are several ways to do it, but different people might vary as to whether they consider the known side effects "serious". The frequency of side effects also varies and factors for any individual woman might increase or decrease the risks. Most importantly, we have no long term (like 20 year) safety evidence, especially for option number 1. Understand this is general information may or may not be applicable to any individual person.

  1. If you use ordinary oral contraceptive pills but do not take the week of blanks at the end of the cycle, but start on the next month's pills, no period will occur. Some women have suppressed pills for years without apparent side effects, but we have no long term evidence that this is safe and will not cause any long term problems.
  2. A second method is injectable depot medroxyprogesterone (Depo-Provera in the US). This has been used as an injectable contraceptive for decades. It will halt or greatly reduce menstrual bleeding in most women. A known side effect in some women is reduced bone density.
  3. A third medicine which will shut off periods is leuprolide (Lupron in the US), which comes in several forms. This will shut off nearly all the important ovarian hormones, including estrogen.

Would the other contributors like to provide the usual chorus of "talk to your doctor about this"? alteripse 21:25, 4 November 2006 (UTC)

Talk to your doctor about this 8-)--Light current 21:35, 4 November 2006 (UTC)
Will you (as in, all of you) stop saying that to every medical-related question? What's wrong with asking for medical advice? It's alright to remind the questioner to see a doctor, but posting "talk to your doctor" without saying anything else is like saying "I don't know, but I want to appear smart". --Bowlhover 00:52, 5 November 2006 (UTC)
Its in the rules. We cannot give medical, legal or something else advice as we are not qualified to do so and do not wish to take on the responsibiltiy of giving advice in therse areas! 8-)--Light current 00:59, 5 November 2006 (UTC)
It's not advice to tell what options exist, and the first person to reply already bolded, go see your doctor. If we can't even tell people to read articles on it, then what is the point of an encyclopedia? There is another one coming out called Anya that stops periods for 2 years straight, then you have to pause / stop. --Wirbelwindヴィルヴェルヴィント (talk) 01:51, 5 November 2006 (UTC)
Light current, I don't agree with the rules. I think it's perfectly acceptable to provide medical and legal advice as long as we make it clear that we're not responsible for any damage. --Bowlhover 02:39, 5 November 2006 (UTC)
Well thats up to you! You asked a question: I gave you my answer. 8-)--Light current 03:04, 5 November 2006 (UTC)
That is why the disclaimer must accompany any medical advice given here. The reader does not know if the person writing the answer is a physician, a well informed lay-person, or a total scammer and nitwit. Edison 02:57, 5 November 2006 (UTC)
Do we really need to mention the disclaimer more than once, though? And can't we just put at the top of this reference desk: "If you ask for legal or medical advice, we are not responsible for any damage that might be caused!" Also, I agree with Wirbelwind that asking for the name of a medicine is not medical advice. --Bowlhover 03:08, 5 November 2006 (UTC)

Thanks for everyone who answered my question. And to assure everyone, I asked this for information and will defiantly consult with a doctor before taking any action. 81.178.122.199 15:14, 5 November 2006 (UTC)

There are medicines that can prevent menstrual cycle in women with very serious side effect. If you want no periods without side effects, wait till Menopause. The Steroids hormones have been proved to increase the risk of few cancers (Breast, Body of Uterus) and increase thromboembolism. Of course Few cancers like Ovarian Cancers have a decreased risk  Doctor Bruno  16:14, 5 November 2006 (UTC)

[edit] Volcanoes

I need to write an essay with the title WHAT IS THE LIKELIHOOD OF VOLCANIC ACTIVITY IN BRITAIN IN THE NEXT MILLION YEARS? Any help would be much appreciated as I am struggling to find information.

Well there's THIS. Although it's not much if you need an academic reference. I found it by googling '"volcanic activity" "great britain"'. You might also try googling '"Volcanic activity" "western Europe"'. Anchoress 21:39, 4 November 2006 (UTC)
Background on the geology of Britain is in Geology of the British Isles. Volcanos are thought to form primarily at plate junctions or hotspots. See if you can determine if there is a possibilty of one of these occuring in the UK. --TeaDrinker 21:49, 4 November 2006 (UTC)
didnt Ben Nevis used to be one? When we used to be over the equator somwhere?--Light current 22:59, 4 November 2006 (UTC)

[edit] What happens when man takes a contraceptive pill?

What would happen if a man regularly took a woman's contraceptive pill for a long time?

I think he'd grow Bitch Tits. --Kurt Shaped Box 21:43, 4 November 2006 (UTC)
Yes I think taking oestrogen can make the breasts grow.--Light current 22:21, 4 November 2006 (UTC)
He'd never get pregnant. Clarityfiend 04:59, 5 November 2006 (UTC)
He will have Gynaecomastia and other signs of hyperestrogenism that are commonly seen with Liver Failure  Doctor Bruno  16:15, 5 November 2006 (UTC)