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January 22

how do i get taller

now i'm over 20 and my height is 5'4" so i want to more tall than before so how can i do?

00:28, 22 January 2008 (UTC)~ —Preceding unsigned comment added by 68.161.204.136 (talk • contribs) 00:28, 22 January 2008

Wear platform shoes? Either that or HGH. Paragon12321 (talk) 01:39, 22 January 2008 (UTC)

Viagra then lie down :D —Preceding unsigned comment added by Shniken1 (talk • contribs) 02:22, 22 January 2008 (UTC)

The questioner might not be male... —Keenan Pepper 02:24, 22 January 2008 (UTC)

The HGH suggestion seems perilously close to (bad) medical advice, but let me just point out that it probably wouldn't work anyway. As I understand it, once the ends of bones like the major ones in your arms and legs close off, which I think they do by the age of 20, hormones will not make the bones larger. What it might do is expand certain other bones, like ones in your face, which could distort your appearance in ways you wouldn't like. This is my personal non-expert understanding and is not meant as advice of any kind.

There is a procedure that we probably have an article on but which I don't know the name of. It involves cutting through the leg bones and holding them apart a small distance via some sort of adjustable metal rigging, then slowly increasing the distance as the bone grows to fill the gap. It's supposed to be terribly painful. Whether it will work on a 20-year-old I don't know. I mention it solely for academic interest--I don't think you'll find a reputable practitioner willing to do it on someone of normal height who just would prefer to be taller. --Trovatore (talk) 02:40, 22 January 2008 (UTC)

(Edit conflict): There is such thing as limb lengthening surgery Distraction_osteogenesis#Cosmetic_lengthening_of_limbs. (You may recall this from the film Gattaca.) But, as far as I can see, you'd have to be insane to go for it. Even if everything goes well you'll be off your feet for the better part of a year. (And if things go wrong, potentially the rest of your life.) That's a high price to pay for a few inches of height.APL (talk) 02:43, 22 January 2008 (UTC)

Perhaps you could try picking clothing that causes an optical illusion of extra height. For females, vertical stripes and a narrow v neckline might help add some apparent height. If your a male perhaps try solid colors. Picking some appropriate shoes could easily add an inch or more, guy or girl. Have a look at human height, you may not be as short as you think compared to everyone else. 152.3.44.183 (talk) 03:03, 22 January 2008 (UTC)

I would urge you to not worry about your height. Yes, I know this is easier said than done, but really: since there's nothing you can do about it, taking it easy and living with it and not worrying about it is the only approach there is.

I'm not saying there aren't people who will disrespect you for being shorter than average. There are such people. But there are also people who will disrespect you for being too tall, or too fat, or too skinny, or too old, or too young, or too smart, or too stupid, or for being male, or female, or white, or black, or just about anything. Don't worry about them, either. Their prejudices are their problem, not yours.

Most people -- and the people who matter -- will respect you for being who you are. There's no surer way to look like a nincompoop and earn people's disrespect than by trying to be someone you're not.

I know several people who are short, and who are self-conscious and defensive about it, and they're real jerks. (There's even a name for this: Napoleon syndrome.) I know several other people who are short, and who don't care at all, and they're perfectly normal people; I don't even notice that they're shorter than average. —Steve Summit (talk) 03:38, 22 January 2008 (UTC)

Hey, I'm 5'4" and I didn't know I was supposed to be short! Julia Rossi (talk) 07:24, 22 January 2008 (UTC)

I should point out that Napoleon syndrome is actually a misnomer. Napoleon wasn't that short. That's a misconception. 64.236.121.129 (talk) 14:41, 22 January 2008 (UTC)

Move somewhere with poor general nutrition. China used to be a good bet, but they're getting taller. Failing that, you should listen to Steve Summit above. What can be offputting about short men is not their height but the rat terrier attitude that sometimes accompanies it. If you're a woman, there's no stigma to being 5'4", so you needn't give it another thought. --Sean 14:20, 22 January 2008 (UTC)

You can become a famous actor and force all the extras on the set to be shorter than you. For example, I was in Camp Pendleton when one of the Rambo movies was filming. They put out a casting call for Marines to play extras. The only qualification was that you had to be under 5'7". -- kainaw™ 15:19, 22 January 2008 (UTC)

Consider travelling in India, Japan, Mexico or the Philippines, see here [1] for human height averages. ; ) Julia Rossi (talk) 04:36, 23 January 2008 (UTC)

What is your reason for wanting to be taller? If it is not for cosmetic reasons then you might be interested to know that Sumo wrestlers who are just a fraction off the height requirement (yes, there is one, but I don't know what it is) have an implant placed in the top of their head above the skull. SpinningSpark 14:58, 23 January 2008 (UTC)

I'm 165-168 cm and I don't consider it a problem. Sure now that I live in New Zealand, I'm probably considered on the short side but who cares? Nil Einne (talk) 17:20, 23 January 2008 (UTC)

Woman care.217.168.4.225 (talk) 00:15, 28 January 2008 (UTC)

leg stab

I remember reading The Island of Dr. Moreau like 10 years ago.. Moreau stabbed his leg with a knife in a specific spot that he said has no nerves, so it doesn't hurt. Does this really exist? --f f r o t h 03:03, 22 January 2008 (UTC)

I'd expect not but I'm also certainly not an expert on anatomy. Bellum et Pax (talk) 03:51, 22 January 2008 (UTC)

Consider it from an evolutionary perspective. Having a point on the body where you could stick a knife in without feeling any pain would represent a survival disadvantage—you could be seriously injured and bleeding heavily and not realize it. Different parts of the skin have different degrees of innervation; your fingertips are more sensitive to touch than the middle of your back. There is no part of a healthy person's skin surface devoid of pain receptors (nociceptors).

Disease or injury can sever or disable the nerves to a part of the body, however. The canonical example is the disease leprosy, where the bacterium involved can kill off peripheral nerves in the body. Injuries to the affected extremeties frequently go unfelt and unnoticed, ultimately leading to the loss of limbs. TenOfAllTrades(talk) 04:38, 22 January 2008 (UTC)

Leprosy only kills nerves? How would incidental injuries going unnoticed make your extremities fall off? Getting punched in the nose would hurt, but even if you notice the pain there's nothing you can do about it and it just heals on its own. Same with nicking your shin on the coffee table or something. I mean, fall off? You'd have to have wire cinched tight around it for hours, or get hacked to pieces with an axe.. --f f r o t h 04:55, 23 January 2008 (UTC)

Things spinning really fast

Why is it that things that spin really fast look like they're going backwards? Like car tires. Bellum et Pax (talk) 06:57, 22 January 2008 (UTC)

They don't, except in movies/TV or under certain types of artificial light. See wagon-wheel effect. --Anonymous, 07:45 UTC, January 22, 2008.

This was here half a year ago, check it out. --Ouro (blah blah) 07:46, 22 January 2008 (UTC)

Western blot

I'm kind of discomforted by the fact that I've done these before, but I can't understand why they work. The primary antibody used in a western blot is typically created (initially) in an immune reaction to the protein of interest. The protein of interest is also denatured and (often with stuff attaching to it as well) in the course of the western blot. And so I'm perplexed that the primary antibody actually binds to the protein at all. I'm hoping someone can correct my confusion. Someguy1221 (talk) 10:10, 22 January 2008 (UTC)

You're quite correct in that many of the antibodies generated against the intact, non-denatured protein won't bind to SDS-denatured, linear protein from a western blot. Usually, however, at least some epitopes present on folded protein are preserved in the denatured protein. Consider a beta sheet, for example. An antibody that recognizes an epitope that runs perpendicular to the strands in the sheet (across several strands) won't work on denatured protein, whereas an antibody that binds to an epitope parallel to the strands in the sheet (following a single strand) may.

In practice, many antibodies are no longer prepared using the whole protein as the immunogen. Instead, short polypeptides (ten amino acid residues, give or take) corresponding to sequences from the protein of interest are synthesized and injected into the animal to generate antibodies. (The peptides are chemically 'decorated' in various ways to make them more attractive to the immune system.) These peptides generally have a 'look and feel' that's much closer to the denatured, extended protein seen during a typical western blot.

In any case, many (polyclonal) antibodies are also affinity purified. Essentially, you coat a column with the denatured protein or peptide of interested and flow the antibody mixture over it. Only the antibodies with the desired binding properties will stick; these antibodies can be eluted (collected) by washing in a slightly more aggressive buffer.

As for the 'stuff attach[ed]' to the protein, I assume that you mean the SDS (or other detergent) used to denature and solubilize the protein. Again, you're correct that high concentrations of detergent would definitely interfere with antibody binding. If you check your buffer recipe for the primary antibody, it will contain little (if any) detergent—perhaps just a dash of Tween to discourage nonspecific binding of the primary antibody. TenOfAllTrades(talk) 16:03, 22 January 2008 (UTC)

Location of spleen (in humans)

Can you help resolve an apparent ambiguity?

In the article Spleen, it is shown as being about level with the liver, just below the left lung.

But in the article Gallbladder is a diagram which also shows the spleen (number 8), which shows it as being a bit lower down.

Thanks. — Alan^✉ 13:46, 22 January 2008 (UTC)

Dare I suggest putting the word "spleen" into Google images? The top graphic, whose source is a US government health agency, seems more likely to be correct than the hand-drawn lower one, just on the face of things. And Google seems to agree. I mean, it doesn't take expert knowledge to figure that one out, is all I'm saying. --24.147.69.31 (talk) 16:18, 22 January 2008 (UTC)

The upper drawing is correct, the lower (which in fact shows the spleen lower than the liver!) is misleading. A normal spleen is palpable in only about 3% of thin people; in the remaining 97% it's above the level of the lowest rib. In contrast, the liver extends much more frequently below the rib cage (a minimum of 5cm in 51% of patients in one study). - Nunh-huh 18:18, 22 January 2008 (UTC)

If the image is misleading, perhaps it should be removed from the six articles it is used in (and the dozens of additional articles in other language projects). 96.227.63.251 (talk) 23:10, 22 January 2008 (UTC)

It would probably be better if it were simply redrawn, and the new version uploaded over the old one. - Nunh-huh 00:41, 23 January 2008 (UTC)

The spleen and liver are lower in children than in adults. Thought that might be interesting.--TreeSmiler (talk) 02:53, 23 January 2008 (UTC)

Or is the rib cage higher? :) - Nunh-huh 05:14, 24 January 2008 (UTC)

Thanks for the replies. — Alan^✉ 19:42, 24 January 2008 (UTC)

Testing an electric fence

In the movies they sometimes throw a piece of wood at a fence to see if it is electrified. Would this work in real life? If not, how can you test it to see if it is electrified? 64.236.121.129 (talk) 14:36, 22 January 2008 (UTC)

Depends on the type of electric fence. Are you planning on breaking into a North Korean prison camp or just crossing a field with cows? --BozMo talk 14:44, 22 January 2008 (UTC)

For cattle-type fences, just tap it. If it shocks you, it works. (NOTE THIS IS AT YOUR OWN RISK --BozMo talk 15:41, 22 January 2008 (UTC)) They are designed to shock cattle, not kill them. For lethal electric fences, that much electricity will charge the air around it. There are many things you can do to check for high amounts of static electricity in the air - such a holding a sheet of paper near the fence. The static electricity will bend the paper. You can experiment easily with a balloon. Rub it on the carpet to get it all charged up and see what various items do when they get close to the balloon. -- kainaw™ 14:53, 22 January 2008 (UTC)

I would not count on being able to identify a lethal electric fence by the electric field in the air around it. According to the electric fence article, "modern low-impedance" electric fences wait until something touches them before delivering the jolt. I don't think the point of this is to defeat detection -- electric fences aren't usually intended to murder the unsuspecting traveler, but rather to deter passage. It's probably more a question of reducing the electric bill. --Trovatore (talk) 23:18, 22 January 2008 (UTC)

How would the fence know when any thing was touching it before delivering high voltage, and why would it wait?--TreeSmiler (talk) 23:32, 22 January 2008 (UTC)

How: it would keep a small potential difference (AC or DC? I don't know) between the fence and ground, and monitor the current. When the current starts to flow, it lowers the boom. Why: That way, you don't have to supply large amounts of power continuously. --Trovatore (talk) 23:43, 22 January 2008 (UTC)

I really wouldn't bother with all that if I was designing the shocking device (and Im sure neither would other electronic engineers). I would just create short duration HV pulses every 500 ms or so. Generation of high voltage at low current does not imply large electrical power input anyway. You could do it, if necessary, from a small 9v battery feeding an inverter.--TreeSmiler (talk) 00:43, 23 January 2008 (UTC)

Well, that would be one approach, but you still need more power than with the detection methodology, so why do you want to waste it? Just to have a slightly simpler design? Plus you'll be putting out an RF signal that might cause interference somewhere. (And I'm sorry, but I don't buy that you can lethally electrify a prison camp with a single 9V battery -- I'd have to see the design.) --Trovatore (talk) 00:55, 23 January 2008 (UTC)

Any voltage can simply be transformed up to a voltage that will cause a lethal current to pass through the human body. The amount of energy required is not that great either (I didn't specify the electrical capacity in Ampere-hours of the battery). See BSI publication PD6519 Part 1. [2]--TreeSmiler (talk) 02:11, 23 January 2008 (UTC)

Well, you said it was a "small 9v battery" -- it's reasonable to assume you're talking about an ordinary one. And you're talking about putting lethal pulses through a whole fence twice a second. I still don't buy it. There's a minimum amount of energy needed to overcome the parasitics to bring the fence up to that voltage, even for an instant, and you're not going to be able to draw enough power to do that twice a second. If you could, of course, you'd drain the battery almost at once, but you can't. Granted that I haven't done the actual calculations here, but come on. --Trovatore (talk) 02:35, 23 January 2008 (UTC)

I didnt say how long the battery would last did I? In fact I emphasized this in my last post by saying 'I didn't specify the electrical capacity in Ampere-hours of the [[battery]'--TreeSmiler (talk) 02:40, 23 January 2008 (UTC)

Dont forget that if there is no load on the high voltage side, there is essentially no energy used there.--TreeSmiler (talk) 02:44, 23 January 2008 (UTC)

You still have the RLC to overcome every time you bring the fence up to the lethal voltage. And actually it had better be a really super-lethal voltage if it's going to fry the target without some sort of circuit that detects the load and provides extra energy. And if you're going to do the latter then I don't think you're saving much complexity over the scheme I was talking about. --Trovatore (talk) 02:56, 23 January 2008 (UTC)

Neither capacitors nor inductors absorb/dissipate any energy. Resistance is not a factor until current is drawn. You dont want a lethal electric current- you want something that is going to deter, not kill or maim.--TreeSmiler (talk) 03:02, 23 January 2008 (UTC)

You don't have to keep wikilinking "energy"; I know what it is. The point about capacitance as a parasitic is that you have to supply a certain amount of charge to get the desired voltage; the actual energy will be dissipated resistively or as RF emissions, or maybe in corona discharge (I can't see how this can possibly work without voltages that will cause arcing). Similarly for inductance. As for your last sentence, you may not have looked back at the context of this thread. We are indeed specifically talking about lethal fences. --Trovatore (talk) 03:08, 23 January 2008 (UTC)

I link not for your benefit, but for others following this thread (sorry). I think you are misguided about the voltages at which corona discharges etc appear. We are actually talking about they sometimes throw a piece of wood at a fence to see if it is electrified. The word lethal is not in the original question.--TreeSmiler (talk) 03:16, 23 January 2008 (UTC)

No, we're talking about For lethal electric fences, that much electricity will charge the air around it. There are many things you can do to check for high amounts of static electricity in the air - such a holding a sheet of paper near the fence. The static electricity will bend the paper. --Trovatore (talk) 03:20, 23 January 2008 (UTC)

OK--TreeSmiler (talk) 03:32, 23 January 2008 (UTC)

In no case will a piece of wood tell you anything. I am not convinced that a sheet of paper will, either. The proper method would be using a volt-ohm meter to test for a high voltage potential between the wire and the ground. MilesAgain (talk) 15:08, 22 January 2008 (UTC)

Not true. A damp walking stick will tingle on a cattle fence. I use that all the time. --BozMo talk 15:41, 22 January 2008 (UTC)

What about a piece of metal? 64.236.121.129 (talk) 15:26, 22 January 2008 (UTC)

Only if it's firmly connected to the ground/earth and not at all connected to you.

Atlant (talk) 15:32, 22 January 2008 (UTC)

What is the possible voltage level, and how much current can it supply? I would want to know both of these things, at least in a qualitative sense. before testing whether it was live. Throwing a piece of wood would be a very poor test. Wires could be at a pretty high voltage before the piece of wood did anything dramatic. A common voltmeter such as you might have in a typical household shop would be unsafe for high voltages (480 V and up) since it could flash over and electrocute the user. Labs and utility workers have used a variety of testing devices such as a "statiscope" or equivalent [3] as well as high voltage digital meters on a long insulated handle. A rule is to test the tester before and after testing the conductor. A "live wire" result shows that the conductor is energized, but a FAILURE TO FIND IT ENEREGIZED DOES NOT MEAN IT IS SAFE TO TOUCH. Utility crews would test it dead, then ground it via approved grounding means, before touching it without high voltage gloves and other protective gear. Edison (talk) 18:08, 22 January 2008 (UTC)

So, peeing on the fence would be a *really* bad idea then? Do people actually do that? --Kurt Shaped Box (talk) 01:44, 23 January 2008 (UTC)

Yes. It was tested on Mythbusters. It was not possible to create a stream steady enough to get electrical current to travel from the fence to the human. -- kainaw™ 01:53, 23 January 2008 (UTC)

Peeing on a low voltage electric fence may be ok, but I certainly would not try it on an 11 kv cable or overhead line (if you can project that far!). The resulting current would, shall we say, smart severely! --TreeSmiler (talk) 02:15, 23 January 2008 (UTC)

Look there are many ways I could advise people to kill themselves with even very low voltage sources, like 1.5 v batteries. Its not difficult. But Im not about to publish that sort of info here (or anywhere).--TreeSmiler (talk) 02:21, 23 January 2008 (UTC)

To try to answer the original question, depending upon the voltage on the fence, I would probably use a voltmeter. If the current was sufficient to light a small (bicycle lamp) electric lamp, you could use that.

I would always use insulated probes tested to withstand the maximum voltage that could possibly be there. I would also use an approved fused meter (or lamp) that could break the maximum fault current that could be supplied by the fence. (Safety warning over)--TreeSmiler (talk) 03:29, 23 January 2008 (UTC)

Also back to the original, my trusty electrical multimeter goes everywhere with me professionally, but I would not normally take it out on country walks (its not sealed against mud and cowshit). I find the best practical indication of electrification is if the fence/wire has been fixed to the posts with insulators, commonly glass or ceramic.

But thats not the reason I posted, I wanted to comment on the first two replies "Are you planning on breaking into a North Korean prison camp . . " and ". . . with a balloon. Rub it on the carpet . . .". Why do the North Koreans carpet around their prison camps? SpinningSpark 14:16, 23 January 2008 (UTC)

Just a note on one thing I've been told (by farmers & hunters) - if you do test an electric fence by touching it, use the *back* of your hand. If it's live, muscle contraction will close your hand and move it away from the wire, as opposed to palm towards the wire, where muscle contraction will tend to close your hand around the wire. I've never had an opportunity to try this, though. -- 128.104.112.34 (talk) 18:00, 24 January 2008 (UTC)

Chemistry: molarity vs. normality

How to convert molarity to normality? —Preceding unsigned comment added by 117.193.226.200 (talk) 15:34, 22 January 2008 (UTC)

Normality is just the ratio of two molarities. See Concentration#Molarity and Concentration#Normality. If you have 2 molar of X, and 3 molar of Y, then Y is 1.5 normal to X. Note that it is not an absolute unit: a concentration is always normal to some other concentration. MilesAgain (talk) 16:14, 22 January 2008 (UTC)

There is a discussion of this in the archives (here) --Bennybp (talk) 17:43, 22 January 2008 (UTC)

Which better to go after if being sexually assaulted (not for the squeamish)

Okay, you all remember when Lorena Bobbitt cut off her husband's...well, you can follow the link, I checked. Anyway, that was just a normal fight - well, it wasn't normal, but what I mean is, it wasn't a sexual assault. If it had been, or if she really wanted to get him, would it have been better to cut off the testicles? Because, then the guy couldn't do anything with his penis anyway. And, furthermore, if a woman is being sexually assaulted, you can't squeeze that off, but wouldn't it be pretty easy to squeeze the testicles not only till the guy fled in extreme pain (I knew someone who had one of those get twisted around and had a lot of pain) but even till they popped? Can they pop? Like I said, not for the squeamish. —Preceding unsigned comment added by 4.68.248.130 (talk) 21:16, 22 January 2008 (UTC)

[4] Let me just say, "oy." Someguy1221 (talk) 21:27, 22 January 2008 (UTC)

Isn't it astonishing that a woman who rips off a man's testicle and tries to eat it can write "I am in no way a violent person?" !!!! That takes balls...but I suppose she has them to spare... - Nunh-huh 22:05, 22 January 2008 (UTC)

Actually someone without testicles can potentially be sexually aroused as it may not eliminate the sex drive completely. I would presume the use of hormone replacement therapy in particular helps to reduce the effects (although the human mind is a amazing thing). See castration for some details. You may want to consider people who have orchiectomy as part of a sex reassignment surgery for male to female intersexuals. Or for that matter, female to male intersexuals who obviously don't and never hard testicles. Many of these people do have sex to some extent I believe. There would I presume be studies into the sex drive and info one how they may improve their sex drive for these people. Even ignoring these sort of cases, there would I presume be some info into ways it can be improved for people who have both testicles removed because they are cancerous or by accident (may not be that common but probably enough that there is some info). You may also want to consider the debate about the efficacy of castration to stop sex offenders (this usually revolves around chemical castration but I'm sure there has been some discussions related to physical castration). Incidentally, castration does mention castration play as a BDSM practice, which stimulates it without actually doing it. I'm not quite sure what this means and being male I'm not sure if I want to know. I presume it isn't talking about chemical castration. Your best bet is probably to cut off the penis after castration Nil Einne (talk) 17:09, 23 January 2008 (UTC)

N.B. it may also be useful to look into spinal cord injuries. These can greatly impair the connection penis and the brain (so to speak). The testicles are still there and so are producing hormones but their ability for arousal is clearly going to be greatly affected. But people with such injuries have ways they can have sex. While obviously this is the opposite of what were are speaking about, there's probably some lessons that can be learnt Nil Einne (talk) 17:14, 23 January 2008 (UTC)

I recall but don't particularly feel like looking up a post on BMEzine's Modblog in which a eunuch described how happy he was with his amputated testicles and replacement testosterone--he was quite adamant that the women loved his empty scrotum. grendel|khan 06:56, 27 January 2008 (UTC)

I suppose for accuracy's sake, we should point out that there was no "fight" involved when Lorena Bobbitt lopped off her husband's penis: he was sleeping on the couch when she mutilated him. In such a situation, Lorena's logical choice was: put the knife down, and go home to mother. - Nunh-huh 05:13, 24 January 2008 (UTC)

Having trained in martial arts classes with both sexes for a number of years, the advice that I have usually heard given is, yes, the testicles are a good target but do not assume your attacker will drop immediately or even react - adrenaline has amazing effects and could easily block or delay the pain reception (from a blow, unsure about more severe trauma). Also, they may not be available to you, for instance if the attacker has your arms pinned and control of your legs. There are plenty of other "squishy" targets available which can be effective with minimal strength and training, for instance eyeball gouging, fish hooking, pulling the attackers head in close and biting the ears/nose. If the testicles do present themselves, I have read on self defense forums that a sharp downwards pull and twist is most effective, apparently rendering some victims unconscious but I have (thankfully) never had to test this theory. 78.32.138.240 (talk) 23:46, 28 January 2008 (UTC)

Snap crackle pop

Before I ask this question, I'd like to assure the overzealous reference desk patrollers that this is not a request for medical advice. It is a request for information on human anatomy.

Last night, I was looking upward and turning my head from side to side when I felt a rather odd "pop" in my neck. I assume this was bumps on two of the vertebrae rubbing against each other; which two would it have been? --67.185.172.158 (talk) 21:29, 22 January 2008 (UTC)

This Cracking joints article seems pretty complete. --Mdwyer (talk) 22:24, 22 January 2008 (UTC)

Glass dust?

http://www.youtube.com/watch?v=YD4quOf0n6E&feature=related

^Harry Potter. At 2:31, wouldn't that glass dust still hurt them? 64.236.121.129 (talk) 21:43, 22 January 2008 (UTC)

Of course not, because Dumbledore protected them with magic. The shield pulverized the glass projectiles, maybe it also slowed them down, or turned them into candy, or completely destroyed them and replaced them with an illusion of dust, or toughened everything on the other side so it would resist the impacts. It's magic, applying physics and common sense won't help you explain what is going on. gnfnrf (talk) 22:03, 22 January 2008 (UTC)

You could go with literal explanations instead. Maybe the writer/director thought it looked cooler that way, or just didn't think about what glass dust would do to a person. Someguy1221 (talk) 22:11, 22 January 2008 (UTC)

Ignoring magic, if glass dust were moving towards a person at that around that velocity, would it be dangerous? 64.236.121.129 (talk) 17:01, 23 January 2008 (UTC)

To counter the impact of any projectile, you want to spread the force out over as large of an area as possible to reduce the impact pressure and you also want to spread the impact out over as long of a time period as possible. Turning a few shards of glass into a powder would help on the first count and possibly also on the second. The shape of the glass dust particles would also be important. Sharp particles would be far more dangerous than rounded particles, which are essentially "sand". Of course, sand is still an irritant in the eyes. StuRat (talk) 05:18, 23 January 2008 (UTC)

See also "Ground glass as (non-)poison". --Sean 14:22, 23 January 2008 (UTC)

Thanks, but that's not really related... Interesting though. 64.236.121.129 (talk) 16:58, 23 January 2008 (UTC)

I guess my point was that things below a certain size aren't sharp. --Sean 01:13, 24 January 2008 (UTC)

I'm afraid that's not correct. 64.236.121.129 (talk) 19:23, 24 January 2008 (UTC)

Or at least the size has to be very small, like individual atoms, for objects to no longer be "sharp". StuRat (talk) 17:16, 27 January 2008 (UTC)

Post-coital urticaria in a penicillin-sensitive patient

Female being treated with amoxicillin. Within minutes post-coitus (with condom), (male) penicillin-sensitive patient developed urticaria around genitals but not on penis. Treated by (somewhat doubtful) GP for drug reaction, and urticaria healed (so this is a science question, not a medical advice question). What I want to know if there are any reported cases of this in the literature? I could not find any. --196.210.102.113 (talk) 21:43, 22 January 2008 (UTC)

If they are, they would be in MEDLINE, but that is probably where you looked. MilesAgain (talk) 13:32, 23 January 2008 (UTC)

Forgive me if it appears that I'm dumbing this down. I am. Maybe it will pull in a better response:

Have you ever heard of someone getting an alergic reaction -- hives -- from something their sex partner was taking? --Mdwyer (talk) 05:33, 24 January 2008 (UTC)

Melonized Steel

We received a specification from a customer for a marine steel part; after machining the part needs to be "melonized". I assume it refers to some sort of heat treating or chemical processing that is required to prevent oxidation. I couldn't find anything on the web except for a Chevrolet melonized gear, but it didn't really show any useful information about what the specification is. I also checked ASTM site and found nothing. —Preceding unsigned comment added by Delriodave (talk • contribs) 21:49, 22 January 2008 (UTC)

'Melonized' appears to be typo for 'melanized', steel which has gone through 'melanization'. I'll guess that by analogy to melanin, this process creates a black oxide layer on the steel. Note that our iron oxide article describes black oxide as follows:

"Magnetite (under the name Black Oxide) is used for coating steel tools [2]. This protects them from corrosion and gives a pleasing appearance.

Atlant (talk) 22:23, 22 January 2008 (UTC)

Could the customer be referring to Melonite processing? In any case, why not ask them? --169.230.94.28 (talk) 22:34, 22 January 2008 (UTC)

Circular motion/ conservation of energy.

Hi all. This question is from an A-level physics exam I took a couple of days ago. I'm posting it here because I got an answer which is quite pleasing if I'm right, so I'd like to know if I am.

It concerns a ride at a theme park which basically consists of a swing with a rigid pole instead of a chain, the length of which is 18m. The question asks: What is the ratio of the force from the seat on the rider to the rider's weight when the swing is at its lowest point, if it is released from a horizontal position?

My working is as follows:

Net force on rider (in upwards direction): $F_{NET}=F_{SEAT}-mg={\frac {mv^{2}}{r}}$

By conservation of energy, ${\frac {mv^{2}}{2}}=mgr$

So $v^{2}=2gr\,$

Substituting into the force equation, $F_{SEAT}-mg={\frac {m(2gr)}{r}}=2mg$

Therefore, $F_{SEAT}=3mg\,$

What we are looking for is ${\frac {F_{SEAT}}{Weight}}={\frac {3mg}{mg}}=3$

Which seems to work out quite nicely, apart from the fact that a friend got $\pi$, which makes me think I've missed something. Can anyone confirm the answer or find a flaw in my working? Thanks Seth Bresnett • (talk) 22:29, 22 January 2008 (UTC)

Your calculation looks OK to me. That means you are feeling an "effective gravity" of 3 g at that point. Which is pretty cool because 3 g is about the maximum effective gravity you would feel in a space shuttle launch. --169.230.94.28 (talk)

If this is correct, then the force at the bottom is independent of the length of the bar. Can that be correct? -Arch dude (talk) 00:42, 23 January 2008 (UTC)

Yes, given standard assumptions. That includes assuming the mass of the rod is negligible compared to the mass of seat+rider, however, which seems unlikely, especially for long rods. [[User talk:Algebraist|Algebraist]] (talk) 00:57, 23 January 2008 (UTC)

isn't it mv^2/2 = mvr, not mgr--155.144.251.120 (talk) 03:00, 23 January 2008 (UTC)

No. Algebraist 10:25, 23 January 2008 (UTC)

Creatine

Sorry for the re-post, but due to the incompetency of some users on wiki I had to repost.

Do creatine phosphate and creatine monohydrate turn into the same thing by the body? —Preceding unsigned comment added by 76.167.156.92 (talk) 22:49, 22 January 2008 (UTC)

Your last question was not lost to "incompetency", it was removed because it appeared to be asking for specific medical advice, which is forbidden on the reference desk. I suppose you can debate whether or not you were asking for medical advice or asking a general question, but please Assume Good Faith. APL (talk) 23:58, 22 January 2008 (UTC)

See phosphocreatine (the name of creatine phosphate). As explained to me, the natural process is that phosphocreatine is made in your liver and transported to the muscles for storage. Then, as needed, it is converted to ATP for short-term energy bursts. Creatine monohydrate is one of many creatine supplements. It will increase the creatine in your body, which should lead to more phosphocreatine production, which should lead to more phosphocreatine storage, which should lead to the ability to have more short-term energy bursts. I use should because I do not know of any proper tests on introducing creatine to the body through supplements. -- kainaw™ 17:37, 23 January 2008 (UTC)

Thanks Kainaw —Preceding unsigned comment added by 71.105.67.123 (talk) 08:42, 24 January 2008 (UTC)

January 23

discovery of how to measure blood glucose with a home blood glucose meter

Background: In the 1960-1970's, people with diabetes tested their blood glucose by using their urine and a clinitest pill or Benedict's Solution. This gave the amount of glucose in the urine that could then be related to the amount of glucose in the blood.In the 80's home blood glucose meters came on the market and have evolved to a small, fast meter that provides blood glucose reading in 5 seconds.

Question 1. I have tried to learn the history of the who and how the details to allow a small and inexpensive meter to read the blood glucose in a drop of blood. Please help.

Question 2. Who discovered that glucose actually attachs to the hemoglobin molecule? Based on that knowledge, a person figured out they can determine the average blood glucose level over the past 2-3 months. Do you know who did this? The test is called Hemoglobin A1C. It came about some time in the 1980's. —Preceding unsigned comment added by 69.105.39.67 (talk) 01:32, 23 January 2008 (UTC)

Re question 2. our article on Glycosylated hemoglobin gives some history about the discovery of HbA1c. hydnjo talk 03:16, 23 January 2008 (UTC)

Re question 1. the Glucose meter#History section identifies the patent holding companies. hydnjo talk 03:22, 23 January 2008 (UTC)

Ichthyophobia

I was wonder what i would have to do to get a page for Ichthyophobia the fear of fish. I myself suffer from Ichthyophobia. --Mr. S.C. Shadow (talk) 02:49, 23 January 2008 (UTC)

You would merely need to start one, my friend by simply clickin on this red link Ichthyophobia (putting down what you know- others will do the rest)!--TreeSmiler (talk) 02:56, 23 January 2008 (UTC)

There you go its happened within 2 hours?--TreeSmiler (talk) 04:14, 23 January 2008 (UTC)

Anchoring a Ship

Please explain the working of an Anchor in a Ship. Why is it used for? How many anchors are there in a Ship? Is it capable of keeping the Ship stable in the sea? Please explain in detail. I have searched Wikipedia. But need details. —Preceding unsigned comment added by Ajuputhuvely (talk • contribs) 05:46, 23 January 2008 (UTC)

Well, there are usually two anchors on large (150+ metres) ocean-going cargo vessels - both at the bow of the ship (one port and one starboard). They are usually mighty heavy things attached via large (large large) chains on a motor (to lift the anchor when moving away), the anchor itself can weigh a good few tonnes and be 2-3 metres long. When the ship is to set anchor, one of them (usually one is enough) is lowered (let fall) until it hits the seafloor and buries itself in it a bit (e. g. when waiting before entering a harbour, this place is called a roadstead, the depth is usually not more than a few tens of metres). Usually the anchor is enough to keep the ship fairly stable, although strong winds can move/spin the ship a bit - but it will not move very far. Further from the shore ships don't use anchors when mooring - one reason is that the ocean floor is too far down, the other is that there's almost no difference, because usually (not always - ships cross the sea using specified routes and corridors) there's nothing around to protect the ship from (like land or other ships), and if so - there's always an officer on deck equipped with a radar and various other equipment, and wary of anything and everything happening in a radius of at least a few kilometres. Any questions? --Ouro (blah blah) 10:26, 23 January 2008 (UTC)

Analyzing notation H7h6 and similar notation

Could you guide me as to where can i find information on decoding tolerance codings —Preceding unsigned comment added by 220.227.67.171 (talk) 06:50, 23 January 2008 (UTC)

Could you give us some context here? Tolerance of what, encoded where, etc.? DMacks (talk) 13:48, 23 January 2008 (UTC)

No one answered this yet? Tut, tut reference desk regulars. I think the OP is talking about ANSI standard fits (for screwthreads, shafts etc). All the answers are in this book SpinningSpark 21:37, 25 January 2008 (UTC)

Training my Macaw (reposting because noone replied)

I've seen videos on YouTube of macaws and other parrots rolling over, lying on their backs with their feet in the air, relaxing and allowing their owners to tickle their bellies or play fight with them. How can I train my Hyacinth Macaw to do this too? I've tried to very gently get my hand underneath and flip her over when she's playing on the floor but she absolutely hates it. --62.136.217.51 (talk) 07:34, 23 January 2008 (UTC)

Hello again. I suspect you can't teach an old macaw new tricks. How old is your macaw? For activities that don't come naturally to an animal, it's usual to start getting them used to stuff when they're young, innocent, trusting and obliging – well, up to a point – and used to being handled a lot. And you must be persistent and very, very patient, use rewards and keep the sessions short so they don't get bored/tired. Also it helps to work with the creature's tendencies (example, dogs roll over since that's what they do in submission behaviour which makes it easy). Does your bird allow you to cradle her to allow tickling to start with? Sounds like quite a challenge. Now you need to wait for a bird wrangler to enlighten us all. Anyone? Julia Rossi (talk) 09:30, 23 January 2008 (UTC)

Check out birdchannel.com/bird-behavior-and-training. They don't describe how to train for that particular trick, but they do cover other similar ones. They also have information on handling macaws. They also have a forum where you can ask questions of other bird owners.--Eriastrum (talk) 20:58, 23 January 2008 (UTC)

In the universe, light exists most abundandtly at what wavelength/energy?

I'm not talking about visible light, but the general electromagnetic radiation. 206.240.27.230 (talk) 11:32, 23 January 2008 (UTC)

Cosmic microwave background radiation is the black-body radiation of the big bang. MilesAgain (talk) 13:34, 23 January 2008 (UTC)

Equivalent to the radiation emitted by a black body at a temperature of 3 Kelvins. See black body radiation--TreeSmiler (talk) 15:56, 23 January 2008 (UTC)

...so we know what the microwave end of the cosmic spectrum looks like, and its structure is nice and simple. But adding in all the photons emitted during the history of the universe since then produces a rather more complicated spectrum, which is discussed here and here. Gandalf61 (talk) 16:46, 23 January 2008 (UTC)

...and we even have an article on this - see cosmic latte. Gandalf61 (talk) 12:25, 25 January 2008 (UTC)

physiology

How does the mammalian ear perform its functions?McTut (talk) 11:59, 23 January 2008 (UTC)

Have you checked out our ear article and the links from there? What questions of yours has that left unanswered?

Atlant (talk) 13:16, 23 January 2008 (UTC)

If you could give neutrinos a negative charge...

Then allowed them to pass through matter, would they collide with protons? If so, what would happen? 64.236.121.129 (talk) 14:27, 23 January 2008 (UTC)

That's a question for which you can make up whatever answer you like. The laws of physics, as we know them, don't contemplate a charged neutrino and can't explain or predict the behaviour of one. Neutrinos don't interact by the electromagnetic force (only by the weak nuclear force and through gravity) and so the idea of them carrying a charge is incompatible with their nature.

It's like asking, "If cars could fly, would a car travelling downward or one travelling horizontally have the right of way at an all-way stop?" Our laws of physics – the 'rules of the road' – can't answer a question about a particle that doesn't exist. On the bright side, if you're writing a science fiction story, you can choose whatever answer is most convenient for your plot. TenOfAllTrades(talk) 15:02, 23 January 2008 (UTC)

Please, you can skip the analogy, I get it. I guess I should rephrase the question. The fact is, neutrinos can interact with matter, although not very often. If neutrinos tried to pass through a light-year of lead, they are slowed by about 50% if I'm not mistaken. So a neutrino should strike a particle at some point, although rarely. My question is, what happens when they strike? 64.236.121.129 (talk) 16:51, 23 January 2008 (UTC)

A neutrino with a negative charge would no longer be a neutrino and would definitely no longer pass through matter. It is mostly the neutrinos lack of charge along with its inability to interact with the strong nuclear force which allows it to pass through matter in the first place. SpinningSpark 15:18, 23 January 2008 (UTC)

Ok so it's not a neutrino anymore, if it possessed the same properties as a neutrino and had a magnetic charge, it would collide with particles of opposite charge? Btw what you said along with its low mass is what allows it to pass through matter. 64.236.121.129 (talk) 16:51, 23 January 2008 (UTC)

The problem is this is a hypothetical question. Only hypothetical answers can be given. The truth is no one can answer your question since no one know how a neutrino with negative charge would behave. NYCDA (talk) 18:44, 23 January 2008 (UTC)

Spinning said they would definitely no longer pass through matter. 64.236.121.129 (talk) 18:53, 23 January 2008 (UTC)

I'm going to have to land on the side of "fairly meaningless question", too, I'm afraid. As already noted, you're changing one of the fundamental properties of a neutrino by assuming charge is relevant (as opposed to, say, proton vs neutron). Your best approximation is to say that it would be like an electron (electrons and neutrinos are both leptons), but as our lepton article notes, there's a massive (give or take a factor of 100000) difference in their masses. With such a vanishingly small mass and an electron-sized charge, a charged neutrino's interactions would be completely dominated by the electromagnetic force -- like electrons, only more so. — Lomn 19:46, 23 January 2008 (UTC)

No one called it a fairly meaningless question. I would appreciate it if you kept those comments to yourself. 64.236.121.129 (talk) 19:21, 24 January 2008 (UTC)

I find it a reasonable paraphrase of the thoughts expressed by the other respondants; namely, that there is no meaningful answer to the question. For that matter, that sentiment is more scientifically valuable than the stuff I wrote about leptons, which is really no more than jargonized daydreaming. I would appreciate it if you'd accept that the most appropriate answers to your questions are sometimes the ones you don't want to hear rather than editorializing about them. — Lomn 19:36, 24 January 2008 (UTC)

Those comments can lead to personal attacks. Please refrain from such comments. 64.236.121.129 (talk) 18:08, 25 January 2008 (UTC)

If neutrinos had charge (or if there were elementary particles similar to neutrinos except that they had charge) then the electron could decay into a combination of charged and uncharged neutrinos without violating charge conservation. As the neutrino is so much lighter than the electron, this would be energetically favourable, and the electron would have a very short lifetime - for comparison, the lifetime of a muon, which is about 200 times as massive as an electron, is a few millionths of a second. So all the electrons in the universe would quickly decay into neutrinos. You might have some equivalent of atoms, with charged neutrinos orbiting the nucleus instead of electrons, but I think their chemistry would be very different, as "neutrino-atoms" would be much easier to ionise than "electron-atoms". In short, a universe which contained charged neutrinos would be entirely different from the universe that we know and love. Gandalf61 (talk) 20:02, 24 January 2008 (UTC)

Interesting. Thank you. 64.236.121.129 (talk) 18:13, 25 January 2008 (UTC)

Science and Consciousness

There has been some renewed consideration of the implications of a Boltzmann brain. As it disects the possibilities, this amazing New York Times article offers, "you yourself reading this article are more likely to be some momentary fluctuation in a field of matter and energy out in space than a person with a real past born through billions of years of evolution in an orderly star-spangled cosmos. Your memories and the world you think you see around you are illusions...Nature tends to do what is easiest, from the standpoint of energy and probability. And so these fragments — in particular the brains — would appear far more frequently than real full-fledged universes, or than us. Or they might be us."

The fantastic article (highly recommended) cruises through entropy (open that graphic up!) and offers that the brains are several times even millions of times more likely than a 14-billion year evolved consciousness. My question is: what are the assumptions about the universe (size, expansion etc.) for this to be true? Sappysap (talk) 16:50, 23 January 2008 (UTC)

It looks to me like the universe must have a finite size (rather than expanding forever) for this to be true. Otherwise Boltzmann brains would get less common over time, and the number of Boltzmann brains ever existing would probably be finite. Assuming it is finite, there's nothing preventing it from being far less than the number of evolved brains. Also, the universe must last forever. If there is a Big Crunch, there will be no possibility of Boltzmann brains forming after it. Finally, the law of increasing entropy must hold true. If the Big Bounce theory is correct, it looks like entropy will be reset to zero after every Big Bounce. — Daniel 17:47, 23 January 2008 (UTC)

Sirius

Hi. Is it possible I saw Sirius' companion or perhaps its ghost image? When I look at Sirius through a window that has fog on it with a 114 mm reflector at 36x, I see a point of light, but an extremely elongated one, and sometimes it even look like a line. This is caused by the window because it is fine when I try it on a star outside. Anyway, at 36x I see a ghost image of Sirius to the left of it. When I look closely it looks like there is another faint line-like object to the left of Sirius, touching its elongated disk. When I zoom in to 90x, I think I see a faint object to the right of it, but I couldn't confirm this because clouds covered the scene. When I zoom into 180x, I think I see a faint object to the right of Sirius. To give you a sense of direction, the star drifts from right to left, and it takes four seconds for the entire elongated image to go into view. So, I am measuring in drift-seconds here, the distance a celestial image moves in one second. Note these are not arcseconds. Sirius appears four drift-seconds long and two wide. Just off the centre of the image I see a tiny bright disk. Anyway, the faint starlike image is at the rightmost edge of the squished disk. Sorry I have to go, I'll add more info later. Thanks. ~AH1^(TCU) 18:45, 23 January 2008 (UTC)

Ok, I'm back. So, anyway, the image that appeared to be the companion probably appeared between mag. 7 and mag. 10. It's hard to estimate because I'm basing it on memory and there were no other stars nearby. By the way, when I looked through my telescope at 36x at both Sirius and Procyon, I saw about 15-20 stars through the window, with fog on it, with occasional clouds passing, with atmospheric interference, and with my relatively poor eyesight. I know none of these stars are its companion because they are too far. Is two shift-seconds a bit too far from Sirius to be plausible? I didn't have to use much averted vision to see it, although sometimes I had to shift my eyes to see it, but it was so faint yet clearly visible that it's hard to tell if it's there. So, what do you think? Normally you need 250mm aperture under good conditions to see its companion, but is it possible that I glimpsed it? Or does the main disk point of Sirius, probably about 1/10 shift-second wide, appearing about 1/3 shift-second higher (in the described orientation) than the centre of the elongated disk, indicate the presence of the companion? At which part of the image relative to Sirius A in this orientation should the companion have been? Or are these ghost images and elongations completely caused by the window? Thanks. ~AH1^(TCU) 22:27, 23 January 2008 (UTC)

You're probably seeing an illusion. Window glass is not optically flat, so double images, distorted images, and the like are quite common. --Carnildo (talk) 23:19, 23 January 2008 (UTC)

Uh-huh.

It happens that there's an article about Sirius B in the current (February) issue of Sky & Telescope. Its separation from the primary is currently 8.2 seconds of arc. Dividing by 360/24 = 15, that's 0.55 seconds of time -- so 2 seconds of time, as you ask about, is too much by a factor of about 4. Incidentally, the article contains a specific caution against seeing a ghost image due to reflections in your optical system and thinking it is Sirius B.

--Anonymous, 07:00 UTC, January 24, 2008.

alka seltzer

what kind of gas is produced when you mix Alka-seltzer with water or H20 —Preceding unsigned comment added by 198.203.81.19 (talk) 20:12, 23 January 2008 (UTC)

Alka seltzer#Chemistry of the effervescence. Someguy1221 (talk) 20:19, 23 January 2008 (UTC)

Fever: Better to tough it out or bring it down?

This is not a request for medical advice. It is a theoretical question asked out of curiosity. It's often stated that a fever is part of the body's strategy for fighting off viral or bacterial infection. If that's so, then wouldn't forcing a fever down (as for example by taking acetaminophen/paracetamol) sabotage this fighting mechanism? It seems to me by reducing a fever, one might possibly make oneself feel less miserable for a longer time vs. more miserable for a shorter time (higher fever → greater efficacy in fighting off the infection → shorter illness vs. lower fever → reduced fighting efficacy → longer illness)? Obviously a critically-high fever must be reduced; in asking this question I'm assuming a noncritical fever. --Scheinwerfermann (talk) 22:48, 23 January 2008 (UTC)

Well, this is basically the question between the "Western medical approach" and what might be called the more respectable philosophies at work in some forms of homeopathy (no, I'm not talking about the "dilute things to nothing" aspects of it, I'm talking about the "symptoms are the body's way of fighting disease" aspects that scientists do often take seriously). The question comes in part down to the question of what do people like better—prolonged but lesser agony or short but intense agony. If I'm not mistaken, most people prefer the prolonged but less intense approach, which for the case of the fever would mean pain relief (in keeping with Western medicine), but in the case of some other things, like ripping off bandages, actually goes against the practice in most hospitals (where nurses usually argue for short bursts of pain). --24.147.69.31 (talk) 22:59, 23 January 2008 (UTC)

(edit conflict)Hi. I probably won't be able to answer your question directly, but this seems like a matter of treating the symptoms or helping fight the source of the symptoms. Although treating the symptoms may make you feel better, it doesn't get rid of the actual disease. While a cold may have no known absolutely certain cure, most drugs that seem to help either helps fight off the symptoms, or in the case of antibiotics helps fight off the germs. However, drugs that help fight the symptoms might help a little, so you don't cough so often that you damage your lung-vocal system and end up with a long-term disease. However, when there is both the choice of treating the symptoms and the choice of treating the actual disease, it would probably be better to treat the disease (provided that it actually works). I'm not an exper on this though, and I'm also not giving any medical advice. Hope this helps. Thanks. ~AH1^(TCU) 23:01, 23 January 2008 (UTC)

The problem with this theory is that we've evolved the "raise temperature to kill invaders" approach, but it's quite primitive, and doesn't have a foolproof "but only up to a certain point" mechanism. People can and do get injured by running too high a fever. --Sean 23:41, 23 January 2008 (UTC)

The body can exhibit excessive responses to disease and injury, but I've been unable to find any studies on the dependence of recovery time on the taking of fever-reducing meds. I'm reminded of this question back from december, which is basically ask the same question but with "inflammation" instead of "fever." Someguy1221 (talk) 03:34, 24 January 2008 (UTC)

Further, with some mild illnesses the fever is the most debilitating symptom. Even if a fever did mean that you'd get better in 3 days instead of 4-5 days, you might still prefer the latter course if you knew this was something you'd get better from anyway. --Anonymous, 37°C, 07:02 UTC, January 24, 2008.

There has been some recent research into the purpose and usefulness of fever. One study (news article:[5] - subscription may be required) found that mice with short life spans rely heavily on fever to fight infection, whereas longer-lived mice use a "bed rest" strategy, with little to no induction of fever. The thought is that short-lived animals can't afford to slow down and rest (wastes too much time), whereas longer-lived animals can avoid the collateral damage to their own tissues that fever produces. If we try to translate this to humans (remembering always that mice aren't humans), if you bring down a fever, although you may prolong the time to recovery, you may possibly produce less damage to your own body as a result. I'm not about to speculate what the appropriate damage/time balance is, though. -- 17:37, 24 January 2008 (UTC) —Preceding unsigned comment added by 128.104.112.34 (talk)

It depends on the illness, mainly. Some sexually transmitted diseases like Gonorrhea can be inhibited or destroyed by a heightened temperature, but many viruses actually trigger the hypothalamus in order to raise the temperature to their optimum temperature. Most bacteria and viruses are at least slowed down by a fever, giving the body more time to mount a defense, but fevers also debilitate the body and are generally unpleasant. Therefore, for some infections, it would be highly beneficial to keep the temperature down. It is obviously more complex and with more exceptions than this. For Common Cold-type illnesses, the discomfort of a fever/weakness afterwards may outweigh a slightly longer recovery time, and it probably wouldn't be a bad idea to suppress it. Ask thy doctor. --.ιΙ Inhuman14 Ιι. 00:27, 25 January 2008 (UTC)

Does light move slowly at absolute zero?

Does light move slowly at absolute zero? ----Seans Potato Business 23:30, 23 January 2008 (UTC)

This question contains some false assumptions. First of all, temperature is only defined for systems in thermal equilibrium. An object at zero temperature emits no black-body radiation, so light cannot be in equilibrium with it. Light itself either has a non-zero temperature (if it has a black-body, or "thermal" spectrum) or an undefined temperature (for any other kind of spectrum, collectively called "non-thermal"). So, light "at absolute zero" doesn't exist at all.

Second of all, zero temperature doesn't simply mean everything moves as slowly as possible. It means everything is in its quantum ground state. But the ground state of the electromagnetic field is the one with no photons in it, again reinforcing my point that light doesn't exist at absolute zero. —Keenan Pepper 23:52, 23 January 2008 (UTC)

It may also be worth noting that the speed of light is really only of special interest in a vacuum (Cherenkov radiation is the easily-observed result of subatomic particles moving faster than the speed of light through a given medium), as that's where the speed is inviolate. Since temperature requires matter, a true vacuum can't be said to have a temperature at all. Whether the speed of light through other materials varies with temperature, I have no idea, though you're then back to the problems that Keenan Pepper addressed above. — Lomn 00:52, 24 January 2008 (UTC)

To get to the heart of what you're asking, your real question is "Does the speed of light vary with temperature?" The short answer is no, because usually when we say "speed of light" we mean "speed of light in a vacuum." In a true vacuum, as Lomn said, there is no matter, and thus temperature has no meaning (at least not the meaning we commonly ascribe to it). The longer answer includes the fact that light slows down in matter (see index of refraction). How much the light slows depends on the material and the wavelength of the light. Presumably the index of refraction (the measure of how much the light slows down) would also be dependent on the temperature of the material. The type of dependence would likely be different for different materials. -- 128.104.112.34 (talk) 17:20, 24 January 2008 (UTC)

You may take an interest on Bose-Einstein Condensates and their effects on the speed of light. --.ιΙ Inhuman14 Ιι. 00:28, 25 January 2008 (UTC)

"In 1999, Danish physicist Lene Vestergaard Hau led a team from Harvard University who succeeded in slowing a beam of light to about 17 metres per second and, in 2001, was able to momentarily stop a beam. She was able to achieve this by using a superfluid. Hau and her associates at Harvard University have since successfully transformed light into matter and back into light using Bose-Einstein condensates. Details of the experiment are discussed in an article in the journal Nature, 8 February 2007." Bose-Einstein condensates are formed at temps extremely close to zero, and have lots of wierd properties. --.ιΙ Inhuman14 Ιι. 00:52, 25 January 2008 (UTC)

Identification of this rock and minerals

Hi. I don't have a picture right now, and one wouldn't show much detail, but here goes. It is a black rock, hardness approximately 4 - 6 on the scale. I tried calculating its specific gravity once, I think I remember the mass as 21g, but I don't remember its volume. Let's see, it's approximately a severely rounded triangular pyramid, apporoximate dimentions: face 1, 3cm x 2cm x 2.5 cm; face 2, 3cm x 2cm x 2.5cm; face 3, 2cm x 2cm x 2.5 cm; face 4, 2.5cm x 2cm x 2cm. The point where faces 1, 2, and 4 join is slightly rounded but not flat, but if you consider it a face then it's 1cm x 1cm x 1.5cm. Approsimate location of origin: Manitoulin Island, Ontario (but I'm not sure). Originally I think it had a "volcanic" smell, or maybe that was the smell of sun-roasted rock. Its minerals are approximately 30 - 900 microns in diameter. It's very smooth, probably smoothened by water. So smooth, that if I rubbed its edge briskly on my hand, it won't scratch my hand (don't try this at home!). It appears dull, but if I rubbed a cloth over it repeatedly it will cause it to reflect a portion of the light, but not the image of the light source, and it will not hurt my eyes if I tried to reflect the image of the sun, but it's too dull and unflat to reflect the sun's image anyway. Finger grease will temporarily ruin its lustre and leave a faint removable imprint. It is completely opaque, although I've managed to view the crystals at the egde of the rock through a microscope via reflection, not transmition of light. The mineral crystals can be red, beige, grey, or reflective-transclucent. Permanent marker usually comes off with repeated washing. There are a few fractures, less than a millimetre wide and deep, although a few of them appear round and can thus be wider. The minerals are far to small to test or look for any cleavage/fracture. What is it? Basalt, maybe? What might some of its minerals be? Thanks. ~AH1^(TCU) 23:45, 23 January 2008 (UTC)

It could be basalt or teschenite. Graeme Bartlett (talk) 05:20, 24 January 2008 (UTC)

January 24

Developmental Biology - Maturation after pairing

There is an animal species that does not complete development and maturation until it has paired with a mate. In other words, juverniles pair, develop to maturity, then mate. They pair for life, as do some other species. I have forgotten the name of the species. Does anyone else knows it?

Thanks,

4.239.0.107 (talk) 01:25, 24 January 2008 (UTC)

Any idea on mammal/bird/lizard etc? --.ιΙ Inhuman14 Ιι. 03:35, 24 January 2008 (UTC)

Probably mammal, probably small in size. —Preceding unsigned comment added by 4.239.6.115 (talk) 20:46, 24 January 2008 (UTC)

Schistosoma mansoni, according to this external article. (EhJJ) 00:34, 25 January 2008 (UTC)

Thanks, the article on Schistosoma is interesting, but the animal I am looking for is not a parasite but a free-living small animal, and it is the male that does not complete maturation until paired (probably the female as well). —Preceding unsigned comment added by 4.239.138.187 (talk) 22:37, 26 January 2008 (UTC)

Soluble solids of coffee

Why do "Gold Blend" style instant coffee granules take so much longer to dissolve in the hot milk than standard blend granules? DuncanHill (talk) 02:31, 24 January 2008 (UTC)

Firstly, I'm intrigued as to why you're dissolving them in milk rather than water, but anyhoo... Solubility of instant coffee generally depends on the shape of the granules and how 'holey' they are. I would not expect the type of coffee used to make them to affect the solubility much; mostly I would expect that to be a product of the drying process. I would suggest looking at the granules under a microscope if you can, to see the difference. Skittle (talk) 02:41, 24 January 2008 (UTC)

I use milk 'cos it tastes nicer! I do have a microscope - good idea, I'll do that. DuncanHill (talk) 02:57, 24 January 2008 (UTC)

I was intrigued because I've only encountered it as a South American thing to do, previously I'd be interested to hear your results. Skittle (talk) 03:29, 24 January 2008 (UTC)

I'll put up pics, but need to buy some "regular" instant first. Preliminary results indicate that the "Gold Blend" type granules are compact masses of fine crystals, with a low level of holey-ness. DuncanHill (talk) 03:34, 24 January 2008 (UTC)

Sounds like they could potentially be conglomerates of spray-dried particles then. These typically have lower solubility than freezedried granules, which have a more 'holey' appearance and are not conglomerates. But, we shall have to wait for a comparison. Skittle (talk) 03:41, 24 January 2008 (UTC)

Ouch! Speed to dissolve and "solubility" are completely different things. Some sugars for example are hard and slow to dissolve but you can ultimately dissolve a lot before saturation so they are very soluble. --BozMo talk 13:18, 24 January 2008 (UTC)

Yes, yes, but in the coffee industry they tend to use the terms fairly interchangably when refering to the exact thing which Duncan was asking about. So replace 'solubility' with 'speed to dissolve' in my earlier answers if it helps. Skittle (talk) 18:55, 24 January 2008 (UTC)

Anyway, I haven't been able to get any decent pics, but I have examined the two types of granule under the microscope. The "Gold Blend" type are, as I said before, fairly smooth compact masses of fine crystals, with few, small holes. Regular type are very irregular in shape, with a high level of holey-ness. Physical testing also indicates that the regular type are much more crumbly. DuncanHill (talk) 09:58, 26 January 2008 (UTC)

This gives the immediate explanation of the difference in time to dissolve (difference in surface area, as sugested by Skittle), but of course leads to the corollary question - why are "gold blend" type granules produced in a different way to regular type granules? DuncanHill (talk) 10:00, 26 January 2008 (UTC)

As you probably know coffee granules are produced by solvent extraction - the structure of the regular granules suggests very rapid solvent removal, the visibility of crystals in the gold blend suggests slower solvent removal (slower crystallisation gives larger crystals often) - so maybe the gold blend granules are produced by a slower process <advert>retaining more of the rich taste you love.</advert>? this was a guess87.102.89.223 (talk) 18:32, 26 January 2008 (UTC)

I think that spray drying would tend to remove more of the 'essential oils'/'flavour compounds' in the process (a bit like steam distillation in some respects) - so may be a less good method to use - but can be carried out a lot quicker (more cheaply then) than freeze drying.87.102.89.223 (talk) 18:36, 26 January 2008 (UTC)

try http://ww.google.co.uk/search?hl=en&q=freeze+vs+spray+drying+coffee&meta= eg http://www.teaandcoffee.net/0105/special.htm

There are two main types of coffee solubles: those that are freeze-dried and those that are spray dried. Giestas points out that spray dried coffee is less expensive to produce than freeze dried. He says, “Due to changes in technology, over the years the gap has widened between the cost to produce freeze dried and the cost to produce spray dried, as it is now nearly three times costlier to produce freeze dried than spray dried.” Freeze dried coffee is frozen at 45-50°C below zero. “This requires lots of energy and equipment,” Giestas says, “so the cost is much higher than for spray-dried, which is processed using a vertical tower.” But the spray dry process, even though it costs substantially less than the freeze dry process, “has improved dramatically.” Giestas opines that “spray dried has kept pace with freeze dried, especially in terms of variety of flavors since each change in the spray dry process yields a change in the taste of the product.” He adds that with aroma recovery technology “we can change the entire taste profile of our product.”

- and read further this article to discover that the aroma needs to be recovered and readded after spray drying...87.102.89.223 (talk) 18:43, 26 January 2008 (UTC)

From http://www.asic-cafe.org/pdf/abstract/16_051.pdf

An advantage of freeze concentration is that little loss of volatile components occurs,"

So just in case you're having a really slow day I'll finish by summarising that more expensive products use the more expensive freeze drying process which produces a better tasting/smelling (but slightly less soluble due to lower surface area to mass ratio) product.87.102.89.223 (talk) 18:46, 26 January 2008 (UTC)

Cool experiment ideas

Hey all, I just recently discovered the Reference desk, and it so happens that a fellow science geek and I are itching to do a non-school affiliated experiment of some kind. We've had several ideas, and we are thinking big:

• Arc Furnace - see Theodore Gray's PopSci column here
• Thermite - Dangerous, yes, but we are going to take full safety precautions and parental supervision, all the good stuff
• Trebuchet - Also potentially dangerous, but same deal as above

Those are the three we came up with on our own.

Here's the question: Can you guys come up with any cool, self-satisfying, 'legal' experiments that would occupy two studious high-school brainiacs for several weeks? Also, is there anything horrendously dangerous/evil about the above ideas we had?

Thanks muchly! --.ιΙ Inhuman14 Ιι. 02:47, 24 January 2008 (UTC)

Assuming you're taking all the necessary precautions, I would note that when my school tried to show us the thermite reaction the flowerpot exploded (instead of iron dripping out the bottom into a brick). When they repeated it a week later, the new flowerpot exploded. So, prepare for catastrophic failure! Personally, I'd be tempted to build a Van de Graff generator, but that can be stupidly dangerous if handled badly.

Any of these plans will require large open spaces, so you can get a good safe distance from the experiment. And make sure you have plans for if something goes wrong, even if you don't think it will. Make sure you think through 'what if (something) happens?'. Do you know what you'd do? Is there anything you should have to hand, just in case? I enjoy these things, but how stupid would you feel if you hadn't planned for something that went horribly, predictably wrong? Skittle (talk) 03:39, 24 January 2008 (UTC)

Hows about a working replica of an ancient siege weapon? [6] Great fun as long as you remain behind it. --TreeSmiler (talk) 04:12, 24 January 2008 (UTC)

Here are a couple things to beware of:

1. If you have no first-hand, hands-on experience with these reactions, it is difficult to know how careful you have to be. It's not enough to say "be as careful as you can be", because you don't necessarily know what to be careful about. If you don't know what the real and likely failure modes are, you can potentially spend all your "careful" energy on something that doesn't matter that much, and totally overlook something that really matters. So it's best if you've seen someone do these things at least once before trying them yourselves, or alternatively, if you can have someone on hand who has done it before who can tell you if you're doing anything foolish.
2. What's considerably more dangerous than doing one of these reactions for the first time, is doing them for the tenth time, showing off for your friends, after you've gotten complacent about the dangers. You must always remember the dangers, and always exercise proper care. I don't want to admit how many times I've hurt myself doing something dangerous, that I'd done dozens of times before, where I made basically the same stupid mistake that a rank idiot would make, by being careless, because I "knew" I knew how to do the thing carefully. But it's not enough to know you're careful: you have to actually be careful.

—Steve Summit (talk) 04:15, 24 January 2008 (UTC)

Yes maybe you should do a risk assessment first (like all professional experimenters have to these days) listing all the things that could possibly go wrong and how you intend to ensure your and other peoples safety if they do go wrong.--TreeSmiler (talk) 04:20, 24 January 2008 (UTC)

You may wish to reflect upon the experiences of David Hahn, and learn from them. DuncanHill (talk) 04:29, 24 January 2008 (UTC)

Aw come on, what could possibly go wrong? --f f r o t h 04:33, 24 January 2008 (UTC)

In terms of cool experiments other than blowing up or smashing things, you might want to have a look at the Old Nassau reaction. It's a crowd pleaser, especially if you do it in a lot of beakers simultaneously. And you get to play around with the delay by varying the solutions. And as long as you dispose of the chemicals appropriately, it's safe. - Nunh-huh 05:06, 24 January 2008 (UTC)

What about someone drinking the chemicals? Is that safe? If not you have to prevent it!--TreeSmiler (talk) 06:25, 24 January 2008 (UTC)

In what universe would "drinking the chemicals" constitute "disposing of the chemicals appropriately"? Certainly not this one.- Nunh-huh 08:20, 24 January 2008 (UTC)

I wasn't suggesting disposal by drinking the chemicals, just pointing out colored liquids might be attractive to young children or animals (esp dogs) and that precautions against anyone drinking them should be taken. Thats all. But that would come into the risk assessment (ie the probability of someone drinking them). Unlikely I admit; but possible.--TreeSmiler (talk) 18:20, 24 January 2008 (UTC)

The trebuchet is very amusing; it's not dangerous at all. What you may find dangerous are the tools you need to cut the wood. I built one for a competition once. --M1ss1ontomars2k4 (talk) 05:33, 24 January 2008 (UTC)

An experiment that I like (because the result is not what most people expect) is to take an insulated wire, attach a short antenna (or just strip it bare) at one end. Get that end as high up as possible (kite, balloons, water tower...). Then, measure the voltage and amperage difference between the end of the insulated wire on the ground and a metal stake driven into the ground. Is there a difference in voltage between the bare wire high up in the sky and ground itself? If so, why? Is it always the same? Why would it change? Is there a reason you should stay far away from the wire if storm clouds come near? -- kainaw™ 13:10, 24 January 2008 (UTC)

This sounds a bit like the apocryphal Ben Franklin attempted suicide experiment--TreeSmiler (talk) 00:28, 25 January 2008 (UTC)

That is because most people are trained from childhood stories to imagine this experiment taking place during a lightning storm. I noted that you should stay away from storms. So, what happens if you do it on a clear sunny day? -- kainaw™ 13:28, 25 January 2008 (UTC)

Make a hologram from scratch. --LarryMac | Talk 17:36, 24 January 2008 (UTC)

Wow, thanks a lot for the feedback! We're not really looking for an overly educational experiment, unless it can be really cool to take data for. I don't want to mess around with Mercury Iodide/poisonous chemicals with the Nassau reaction, though Orange and Black do happen to be my school colors...

"But it's not enough to know you're careful: you have to actually be careful." Great advice, thanks! We have access to people that know what they are doing, and will research the experiment that we choose to do fully before we start preparing.

Yes, I've heard of the Radioactive Boy Scout, and we do not plan to mess with radioactivity/other phenomenon like that.

• (Inserted) made that a link --Anon, 20:03 UTC, Jan. 24.

I'll add the electricity experiment to that, it sounds very neat.

Any other ideas?

--.ιΙ Inhuman14 Ιι. 17:59, 24 January 2008 (UTC)

Helium. --NorwegianBlue ^talk 21:54, 24 January 2008 (UTC)

Thanks, but no thanks. There was an interesting program on making liquid helium, though... but that'd be too much money and glasswork...--.ιΙ Inhuman14 Ιι. 23:24, 24 January 2008 (UTC)

U bend in steam pipes

Why are there U bends in long steam pipes that are fixed at both ends? I know this sounds like a homework question; that's because it is. Obviously I would not have asked, however, if I didn't think someone here could give me an answer better than the one I came up with. I figured that when steam doesn't flow the pipes, the pipes will contract. If the two ends are fixed, a pipe without a U bend would pull away from whatever it's attached to. However, with a U bend the bend can give the pipe some leeway. Does anyone have a better answer? --M1ss1ontomars2k4 (talk) 05:32, 24 January 2008 (UTC)

Your answer is basically correct. What does metal do when it get hot? Expand, contract or stay the same? If there were no U bends, what would happen to the pipe?--TreeSmiler (talk) 06:19, 24 January 2008 (UTC)

Your answer is theoreticaly correct, practically almost correct. What (average) temperature is a pipe when installed? what happens after it is put into service? is there a difference between steam lines and coolant lines? would you use the same approach or a different approach for a coolant line? extra credit: are there any dynamic effects? (hint: water hammer.) would a u-bend ameliorate or exascerbate dynamic effects? -Arch dude (talk) 23:41, 24 January 2008 (UTC)

colliods

why that some colliods are homogenous? —Preceding unsigned comment added by 125.60.241.164 (talk) 10:54, 24 January 2008 (UTC)

You mean a colloid? A mixture could be evenly mixed. DMacks (talk) 16:09, 24 January 2008 (UTC)

Two non-medical questions related to health

Request for medical diagnosis removed. "I have X symptom, why?" is clearly such a request, regardless of the accompanying disclaimer. — Lomn 14:19, 24 January 2008 (UTC)

Recently, a person whom I know distantly was found pale and almost bloodless. He was taken to the hospital and is now in a stable condition. The fact is that he had no external wounds or blood loss and had suffered no physical trauma which could have caused an internal hemorrage. I don't want to ask his family as they are suffering with his illness, but I'd like to get an idea of what happened to him.

This is not a non-valid medical question either; the person in question is already under expert medical care and this question only seeks some information on the nature of his illness.

Thank you. -- Leptictidium (mammal talk!) 14:03, 24 January 2008 (UTC)

This person you know could have any number of conditions, but most likely a form of anemia. The article lists the several types of anemia that exist, as well as how to distinguish between them. (EhJJ) 15:28, 24 January 2008 (UTC)

Gas leaks

Hi. I hope I'm writing in the right place. Anyway, my stove had a clicking noise last night. It wasn't lit, but it kept making the same noise as it usually does if it's being lit. I called the fire department and they came and checked it out, but I was just wondering - I should've asked them really - if I did a right or foolish thing when I turned on the stoves following the noise. I couldn't tell if there was any leak, so I figured, it's better to burn off any gas than to leaving it hanging somewhere. But today I remember that you're not supposed to light a fire or even turn on a cellphone when you have a gas leak. So, did I do a foolish thing? Thanks. —Preceding unsigned comment added by Imagine Reason (talk • contribs) 19:51, 24 January 2008 (UTC)

When I last had a gas range, I was instructed to immediately vacate the house when I reported a slight smell of gas. If you've got any reason to suspect a leak (and most gas is doped with a super-smelly chemical to make leak detection easy), then evacuation is your best option and testing the stove igniter is one of the worst things you can do. — Lomn 20:06, 24 January 2008 (UTC)

I agree with Lomn about the safety stuff. If in doubt, get it checked out (and it sounds like you did, well done). Having said that, my gas cooker often keeps clicking if one of the rings is very slightly on, and it can be stopped by making sure they're all completely off. The clicking is usually a piezoelectric mechanism used to create a spark to light the gas, so if it's clicking, then it's likely that any lurking gas would already have been ignited. BUT - if there is any lurking gas then you really don't want to be 'burning it off', unless you want to be losing your eyebrows and/or your roof! So if you can smell gas, don't wait around to turn things on and off, just get out and call for help. Eve (talk) 21:50, 24 January 2008 (UTC)

Ok, I won't light the stove next time. Question: is the piezoelectric mechanism independent of the gas valve (when you turn the dial, you're activating both, though, right)? That is, when it's making the clicking noise, is the gas automatically being released? Imagine Reason (talk) 04:13, 25 January 2008 (UTC)

On mine, the ignition mechanism starts going just before any gas is released, so it's just about posible to leave it clicking but not have any (much?) gas. But that will depend entirely on the design of your stove, so I have no idea. And don't rely on it. Eve (talk) 09:42, 25 January 2008 (UTC)

The igniter on a residential gas stove (cooker) isn't piezoelectric. (Outdoor barbecues where you push the red button and it clicks are the peizo ones.) Instead, the igniter takes mains electricity, runs it through a series if switches (one per gas tap/valve, with all the switches arranged in parallel, and then converts that mains electricity to a series of high voltage pulses. If any of the switches on the several gas taps are closed or even just sufficiently electrically leaky, the igniter may start operating, with or without the gas tap actually being open. Last time I looked, the circuit was an SCR-based relaxation oscillator.

Atlant (talk) 13:00, 25 January 2008 (UTC)

By the way, the practice of adding smelly stuff to gas, as mentioned by Lomn, was inspired by a disaster in 1937 when a major gas leak was not noticed and hundreds of children were killed. See New London School explosion. (That's Texas, not Connecticut.) --Anonymous, 23:24 UTC, January 24, 2008.

!! Imagine Reason (talk) 04:13, 25 January 2008 (UTC)

I think you'll find that for natural gas, the added odorant is Methanethiol (Methyl Mercaptan) rather than ethanethiol.

Atlant (talk) 13:03, 25 January 2008 (UTC)

Well, I went by what it said at Thiol#Odor, plus the fact that I've heard ethyl mercaptan (another name for ethanethiol) mentioned in that context. --Anonymous, 20:08 UTC, January 25.

Out of curiosity, what's the danger from a cellphone? Seems rather remote. I'd be more worried about static electricity—don't wear rubber-soled shoes on the carpet—in a gas leak than a cell phone. --24.147.69.31 (talk) 04:08, 25 January 2008 (UTC)

It's probably easier to lay a blanket "Get the heck out!" prescription on people than to try and explain exactly what's safe and what's not in the presence of a gas leak. Tell them it's okay to use a cell phone and someone will try to use a cellphone with a dead battery; they'll then plug in the charger and...

Atlant (talk) 13:04, 25 January 2008 (UTC)

Firing flare guns at people

Apparently, it's considered faux pas to fire a flare gun at someone because it sets them on fire. If this were to happen, would it not be a simple case of stop, drop and roll, or does it cover the ungrateful recipient with something that makes the fire more difficult to shake? --Seans Potato Business 22:46, 24 January 2008 (UTC)

Emergency flares are generally designed to keep burning under hostile conditions (driving rain, high winds, extreme cold, etc.), so they're quite hard to put out. If the flare is not tangled in one's clothing, stop, drop, and roll should put the fire out -- as long as you don't roll over the flare. --Carnildo (talk) 23:19, 24 January 2008 (UTC)

They burn right down into the flesh, don't they? I suppose you'd have to do your best to pull it out before you stopped, dropped and rolled. Then again, that's probably not the least painful/most healthy thing to be doing either. --Kurt Shaped Box (talk) 01:33, 25 January 2008 (UTC)

According to the Nicole Kidman picture Dead Calm, if someone shoots an emergency flare in your mouth you should fall off a sailboat. --Sean 23:22, 24 January 2008 (UTC)

Do you have to be within the vicinity of a sailboat for that to work? ----Seans Potato Business 23:47, 24 January 2008 (UTC)

No, but it's easier that way. *rimshot* —Ilmari Karonen (talk) 01:26, 25 January 2008 (UTC)

A search brought up this video. If it’s real the guy got off remarkably easily. Possibly the flare did not have time to light before it impacted his head. This video on the other hand is a bit more disturbing. The kid is lucky to have gotten away with only a few second-degree burns. --S.dedalus (talk) 03:42, 25 January 2008 (UTC)

Wow. How did they even get the guy to volunteer? bibliomaniac15 03:44, 25 January 2008 (UTC)

Boys will be boys. I'm more curious about his vowels: is that a local or a generational thing? —Tamfang (talk) 09:25, 25 January 2008 (UTC)

One word. Jackass. --Kurt Shaped Box (talk) 12:01, 25 January 2008 (UTC)

Three words, often famous last words: "Hey, watch this!"

Atlant (talk) 13:09, 25 January 2008 (UTC)

A few more:

• "Don't worry - it's not load..."
• "I wonder what happens when I do *this*?"
• "It's okay, I'm a good driver..."
• "What a cute little bear cub..."
• "Ten bucks says that I can swallow this..."
• "Shut up! I can reach it..."
• "I've done this *hundreds* of times..."
• "This is going to be so cool..."

--Kurt Shaped Box (talk) 17:15, 25 January 2008 (UTC)

At work, the oft-quoted famous last words are "what could possibly go wrong". --f f r o t h 16:16, 27 January 2008 (UTC)

You forgot "Hold my beer a sec..." 78.32.138.240 (talk) 00:00, 29 January 2008 (UTC)

January 25

cardiac muscle tissue

i need to know what cell is cardiac muscle tissue is made out of. —Preceding unsigned comment added by 24.151.37.249 (talk) 01:53, 25 January 2008 (UTC)

Muscle cells are myocytes. The muscle cells of heart muscle tissue are called cardiomyocytes. But that's just "heart muscle cell" in Latin, so knowing the name may teach you something about Latin, but doesn't add to your understanding of the heart.- Nunh-huh 02:38, 25 January 2008 (UTC)

Gulls again...

The sea was very rough and very high this afternoon. The water was about 20 feet higher than usual, with some massive waves crashing down.

The water was also covered with hundreds of paddling gulls of various species, both large and small. They were getting absolutely hammered by the waves, tossed about like driftwood on the surface or getting covered by a couple of metres of foaming, churning water every few seconds and bobbing up the other side. Unsurprisingly, they didn't seem to be that bothered by it (gulls are hardy, waterproof seabirds, after all). The strange thing was that there were more gulls in the water on a day with the worst tides I have seen for years than there usually is on a 'normal' day. It was as though the gull flock had seen the state of the water and made a conscious decision to go for a swim *because* it was rough...

Any suggestions as to why? I did consider that the water may have churned up some tasty invertebrates from the seabed or confused some fish into heading to the surface but looking at the state of it out there, I'd be surprised if the gulls were able to keep still long enough to nab anything. --Kurt Shaped Box (talk) 02:35, 25 January 2008 (UTC)

Perhaps it's just being in their element – prefering to ride out the gusts on water than being knocked about on a cliff face – a bit like sailors who claim to feel safer at sea than on land, in a raging storm. You'd have to wonder about this claim in the light of conditions in some of the Sydney to Hobart yacht races[7], though. —Preceding unsigned comment added by Julia Rossi (talk • contribs) 10:02, 25 January 2008 (UTC)

urea again

wat mineral nutrient can i use to turn urea to a nitrate? —Preceding unsigned comment added by 76.14.124.175 (talk) 05:06, 25 January 2008 (UTC)

I'm not sure what you mean by "nutrient" to turn urea into a nitrate, but a strong oxidizing agent (concentrated hydrogen peroxide, nitric acid, permanganate) should be able to affect this transformation. As for more specific procedures, I can't give you any more information. Warning: strong oxidating agents can screw you over pretty badly, as can strong mineral acids.18.96.6.239 (talk) 05:17, 25 January 2008 (UTC)

somthing about bactiria, but anyways do u know were i can get the specifics? cuz being the scientist i am i'll try manual or no manulal! —Preceding unsigned comment added by 76.14.124.175 (talk) 05:22, 25 January 2008 (UTC)

Um, if you don't know what you are doing you're going to blow your fingers off making urea nitrate. It's highly explosive and very dangerous and screwing up in making it can lead to lots of nasty results, if I recall correctly. --24.147.69.31 (talk) 22:13, 25 January 2008 (UTC)

science fair, please help

ok, the science fair is coming up and i need a realy good idea from some one smart and creative, —Preceding unsigned comment added by 76.14.124.175 (talk) 05:10, 25 January 2008 (UTC)

The Manhattan Project? More seriously, are Tesla coils still considered impressive? A robot doing something unique? Do you know anyone who'll let you do some recombinant DNA technology?

Atlant (talk) 13:13, 25 January 2008 (UTC)

If you want to win at the science fair, you need to know what is being judged. At most schools, it isn't "Who can build the most impressive thing with lights and sounds and bubbles..." It is "Who can form a hypothesis, test it properly, and draw a scientific conclusion from the tests." So, the "good idea" is simply a matter of forming a hypothesis that you can test in both a controlled and uncontrolled environment. A common example is to get 10 feeder mice or goldfish. Form a hypothesis about how changing something in their natural environment will affect them. Put half in the normal environment and half in the controlled environment. Do your best to scientifically measure the change in the mice/fish. At the end of the experiment note how the observations either met or failed to meet your hypothesis and draw a conclusion. For example: What happens if half the mice get sugar water as a treat three times a day and the other half get Splenda-water three times a day? What if you do it with 3 getting normal water, 3 getting sugar water, and 3 getting Splenda water? -- kainaw™ 13:37, 25 January 2008 (UTC)

Of course, then you've got a lot of mice left over to figure out what to do with. --24.147.69.31 (talk) 16:15, 25 January 2008 (UTC)

Free Willy Free Mickey? jeffjon (talk) 16:44, 25 January 2008 (UTC)

If it were me, in this day and age, I would probably not try to do some tired old natural sciences experiment, but try to do something a little more in the realm of the social sciences. An example of the sort of thing I am talking aout: Find a few kids who are described as "popular" by your peers. See if they are willing to participate in a experiment regarding fashion and memes. See if they will wear some new article of clothing that won't look absurd but is not something they or their peers currently wear. See if they will help you track how many other people start wearing the same thing, and who they are. Are they close friends or more distant? Are they "popular" people or not? Etc. Consider ways in which you could use the internet as a big experimental pool — can you drive traffic to a meaningless page? How so? From what sources? What seems to work best? (Google Analytics, or similar software, would help you get the numbers of that sort of thing). Anyway, I think something like either of those would look a lot more fresh than the old "where does mold grow" sorts of things that they've been doing for decades. Even something as mundane as "how do people at my school use the internet?", with lots of boring surveys (and then see if the IT people at the school can get you some raw, anonymous data to see if the trends match up with how people report), can be trussed up much more interestingly than a lot of the sorts of natural science experiments you're going to be able to come up with, because frankly most of that low-hanging fruit has long since been picked. --24.147.69.31 (talk) 16:58, 25 January 2008 (UTC)

Here's a good project: try to answer this question posted right here on this very Reference Desk!

I'm quite serious; this would be very easy to do using ordinary materials you have around the house. It would be a perfect application of the scientific method, and you'd be quite likely to learn something new, some facts generally unknown outside of perhaps a toaster manufacturer's secret internal lab. —Steve Summit (talk) 15:41, 26 January 2008 (UTC)

OK, I'm feeling charitable, so I give you a winner for free. My daughter's project was judged "outstanding" at her high school and regional science fairs and went to the state fair. She implemented a Michelson interferometer using really cheap components and techniques. she demonstrated that her piezoelectric positioner could reproducibly move a mirror to any position across six wavelengths of red light. She hacked a $2.00 piezoelectric buzzer to get teh actuator, and she drove it using two nine-volt batteries and a potentiometer. Her light source was a $1.00 lazer pointer, and most of the mirrors were plain old cosmetic mirrors. The only "lab-quality" components were a very small "beam-splitter" (a half-silvered mirror) and a very small front-surface mirror. She recorded the results using a webcam connected to her computer. She built her own optical bench instead of buying one, using plain old nuts and bolts to perform coarse and fine alignment. The beauty of this is that you ger spectacular results for very little effort. WARNING: even $1.00 laser pointers can be dangerous to your eyes. Learn laser safety before you use a laser pointer: I would like to fire most of the marketing department of my company because the idiots use the damn things without understanding the safety issues. -Arch dude (talk) 03:19, 27 January 2008 (UTC)

Subconsciousness

When was the first idea of their being a human subconsciousness? —Preceding unsigned comment added by 74.138.83.10 (talk) 05:13, 25 January 2008 (UTC)

Unconscious mind should be able to answer your question. --S.dedalus (talk) 06:54, 25 January 2008 (UTC)

Posting at multiple desks is a no-no, 74. See policy top of this page. Julia Rossi (talk) 10:13, 25 January 2008 (UTC)

is there any sensor that checks the intensity of light

s there any sensor that checks the intensity of surrounding environment light —Preceding unsigned comment added by Chandar86 (talk • contribs) 12:27, 25 January 2008 (UTC)

In the general class of photodetector we find photoresistors ("photocells"), photodiodes, phototransistors, and solar cells will all do that. Turning to more obscure devices, there are photomultiplier tubes, photo-TRIACs, and all of the image sensors used in cameras. And photographic film and the retina in your eyes, of course, but those are probably not what you had in mind.

Atlant (talk) 13:14, 25 January 2008 (UTC)

Light meter used by photographers?--TreeSmiler (talk) 01:20, 26 January 2008 (UTC)

Old people leaving the gas on

My grandmother can't leave my grandfather alone for long periods because he has a tendency to leave the gas going on the oven. Is there some device that will prevent this from happening or perhaps emit a warning when the gas has been on for an extended period? ----Seans Potato Business 12:54, 25 January 2008 (UTC)

The obvious solution is to get an electric stove. However, there are many gas detectors you can purchase. -- kainaw™ 13:30, 25 January 2008 (UTC)

If the gas is left on and lit, a gas detector is unlikely to be of use. DuncanHill (talk) 13:40, 25 January 2008 (UTC)

Most modern gas appliances have a heat sensor and will turn off or right down if left unlit. I think this is mandatory on new ones sold in the UK but I have no idea about elsewhere. But as you say left lit is more of a problem--BozMo talk 13:45, 25 January 2008 (UTC)

That's also one of the most expensive solutions. Especially when you consider that electricity costs three times as much per unit energy. The gas is indeed left while lit. ----Seans Potato Business 14:26, 25 January 2008 (UTC)

I suggest getting a carbon monoxide detector as gas ovens are not usually vented. This habit sounds fairly harmless to me, but how long is a long period? If his wife lives with him, as implied, perhaps address why he needs to turn the oven on at all? To keep warm?--Shantavira|^{feed me} 15:47, 25 January 2008 (UTC)

Maybe he cooks? DuncanHill (talk) 15:57, 25 January 2008 (UTC)

On a state pension, leaving the gas on is not harmless! And of course its for cooking. A "long period" is however long it is until his wife notices that the gas has been left on. The point is, his wife doesn't want to have to always be with him. ----Seans Potato Business 18:58, 25 January 2008 (UTC)

Shantavira suggests a carbon monoxide detector. First, gas that you burn for cooking may not contain carbon monoxide; that depends on where you live. In many countries it is natural gas, which is pretty pure methane. Second, carbon monoxide detectors are intended to prevent poisoning. With fuel gases, the main risk is explosion, and conditions of detection may be different. See under the item #Gas leaks above!

The obvious solution does seem to be to replace the stove with one that will not allow dangerous amounts of gas to accumulate. I would expect this to be true of any modern gas stove, but if you aren't getting an electric stove then you should talk to people who know about the gas regulations in the country where you live. I would start by talking to the gas company. --Anonymous, 20:19, edited 20:22 UTC, January 25, 2008.

Carbon dioxide is not necessarily part of the gas supply; rather, it is produced by incomplete combustion (combustion without sufficient oxygen). Burn pure methane in a poor supply of oxygen and you'll get lots of carbon monoxide (and some carbon dioxide). Burn pure methane in a good supply of oxygen and you'll get lots of carbon dioxide (and other products), and relatively little carbon monoxide (but you'll still get some). Angus Lepper^{(T, C, D)} 23:55, 25 January 2008 (UTC)

Well, sure (except you meant "monoxide" the first time). But we're not talking about carbon monoxide formed that way. --Anon, 01:50 UTC, Jan. 26.

Forgive me if this causes pain. Most people in you grandfather's situation are suffering from middle-stage Alzhiemer's disease. This is progressive, so most people in this situation will not be able to continue cooking for very long. Thus, a solution that costs a lot or that cannot be implemented immediately is probably not worthwhile. That said, every day you can gain for your grandfather is good, so let's look at the science. If I understand the problem, he is leaving the stove lit. Adding hardware to the stove itself is going to be expensive, so you should think about a separate heat monitor connected to an alarm. If you grandfather cannot respond to an alarm and shut off the gas, then I fear that he should not be left alone. You can create the alarm system with a computer and some thermometers or thermostats, or with a computer and an infared videocamera. The videocamera is probably easier since it need not be attached to the stove. The solution (computer+camera+software) will be a good deal cheaper to configure and install than just about any special-purpose equipmetn, and you can re-purpose the components later as needed. No, I do not know of any specific software to do this, but you can probably get someone to hack something up quickly. any junk computer (free or less thatn $100 used) can do the job. Most cheap ($20) webcams can be hacked to sense infrared by removing the infrared filter, or yuo can buy a cheap "security" webcam taht does not have the filter in the first place. Your "image recognition" program will simply look for the hottest spot in the image: trivial. The program is also trivial: If the hotspot exceeds a threshold for too long a time, play an audion alarm. If the hotspot persists for another 15 minutes, the computer can call a telephione number or send a test message. There is a huge amount of free softwrae infrastructure for this: google Misterhouse. -Arch dude (talk) 02:46, 27 January 2008 (UTC)

There actually are devices for this. They detect motion and will turn off if someone is not in the room. Sorry, but I don't remember the names. I know consumer reports reviewed a few of them a while ago (year or two maybe). They are pretty expensive. Ariel. (talk) 08:04, 28 January 2008 (UTC)

Hangover, sleeping position dependent

Whenever I enjoy a few drinks, if I lie with my head facing left my head-ache/head feels a lot more painful than if I lie with my head facing the other way. This is during the night after having had some drinks. Anybody any ideas why this would be? —Preceding unsigned comment added by 194.221.133.226 (talk) 13:17, 25 January 2008 (UTC)

For lack of experts as yet, I'll guess you could look at Carotid artery or the Jugular vein (see diagrams) since these major blood vessels are in the neck and pressure might affect them, do you think? Then there's the hangover and red wine headache articles. Since the hangover article is dense language, go for the talk page discussion. Julia Rossi (talk) 02:16, 29 January 2008 (UTC)

what is the areodynamic function of flaps

The position of the leading edge slats on an airliner (Airbus A300). In this picture, the slats are extended.

A close look at the spoiler (the parts of the wing that are raised up) during the landing of an Airbus A321.

I know that flaps are used to control a plane better while landing and takeoff , but if it is so useful then why can`t we use it on the whole flight .What is arrodynamic secret behind flaps and do they work--Man manoj1990 (talk) 13:56, 25 January 2008 (UTC)

Flaps increase both the lift and the drag of a wing. More lift means better control at low speeds (particularly landing; most planes use less flap when taking off), but more drag means more fuel used. At cruising speeds, the lift is unnecessary and the fuel is expensive. — Lomn 14:47, 25 January 2008 (UTC)

Yep. It's easy to notice this yourself, if you can see the wing from where you're sitting. It's very noticeable when the flaps go all the way up- they make lots of noise and slow the plane down in a hurry. Friday (talk) 16:00, 25 January 2008 (UTC)

Please don't confuse flaps with speed brakes and spoilers. Flaps extend rearwards and downwards, move slowly, and usually involve rather-noisy jackscrews. The increase the overall curvature of the wing. Spoilers are panels that hinge upwards and move rather quickly. Speed brakes tend to increase drag but not change lift; I don't think you'll see them much on commercial aircraft. You may also notice slats, moving elements similar to flaps but on the front of the wings.

Atlant (talk) 17:21, 25 January 2008 (UTC)

Very true, flaps are not the same as air brakes. Nevertheless, Friday is correct that flaps do have a slowing effect, especially when applied by a novice pilot too quickly. The reduction in speed is a useful effect when landing as well as the increase in lift. SpinningSpark 22:09, 25 January 2008 (UTC)

It's not really a matter of "better control at low speeds", but of not falling out of the sky at low speeds. The purpose of flaps on a fixed wing aircraft is to reduce it's stall speed (V_s). As the speed of an aircraft is reduced the angle of attack must be increased in order to maintain level flight. If that angle is increased beyond a certain critical limit, then all of a sudden the wings stop generating any lift at all, the aircraft is no longer flying but falling. This is called a stall and is not a good thing to have happen when you are near the ground, such as during a landing.

Flaps change the shape of the wing's airfoil (increasing the camber), generating more lift at lower angles of attack but at the cost of increased drag. Extended flaps allow the aircraft to fly a slower and steeper approach and landing, safer and less wear and tear on such things as struts and tires. For the rest of the flight, you usually want to go as fast as possible, you want a "clean" configuration with minimum drag, and the flaps are unnecessary.—eric 01:38, 26 January 2008 (UTC)

Hydrocodone

Can hydrocodone be taken with other medications such as augmentin? —Preceding unsigned comment added by Jokerkace88 (talk • contribs) 16:12, 25 January 2008 (UTC)

Question and answer removed per our no medical advice policy. I suggest you see a pharmacist or doctor about this as we are not qualified to give you advice about possible drug interactions. You should always inform your doctor and pharmacist about any drugs you are already taking when getting a new prescription so they can advise you appropriately. Nil Einne (talk) 20:02, 25 January 2008 (UTC)

Note that you can usually look up known drug interactions pretty easily. Just google the name of the drug and the word "interactions" and you'll find a lot of information. But call up a pharmacist -- they'll be able to tell you very quickly and it shouldn't cost anything. Note that if you ever have questions about medication you are taking, your pharmacist is required by law (in the US, anyway) to chat with you about any concerns or questions you might have. (Hopefully by not trying to "answer" but merely explaining how an answer might be found, this won't violate the rather draconian enforcement of the no-medical-advice policy.) --24.147.69.31 (talk) 22:08, 25 January 2008 (UTC)

Bear in mind of course you can easily misunderstand the data as published which is one of the reasons pharmacists usually have to go through 3 years of more of education plus on the job training before being able to advise people on what they should or should not do with their medication Nil Einne (talk) 15:01, 26 January 2008 (UTC)

Errm ... I'd just like to point out that, as phrased, the questioner is asking for medical information, not medical advice, so there is no reason to remove question or answer. If they had asked "Can I take hydrocone with other medications ?", then that would have been a medical advice question - but that wasn't what they asked, and we shouldn't jump to conclusions about the intentions behind questions. Gandalf61 (talk) 10:13, 26 January 2008 (UTC)

It's the same thing. We always err on the side of caution with medical advice Nil Einne (talk) 15:01, 26 January 2008 (UTC)

It's definitely not the same thing. We have very clear and precise guidelines about what constitutes medical advice. Wikipedia:Reference desk/guidelines/Medical advice defines medical advice as a diagnosis, a prognosis or a suggested form or treatment. None of these are present in this question. Wikipedia:Reference desk/guidelines/Medical advice also says "Note that questions may be about a medical topic ('What is sleep apnea?', for example) without necessarily seeking medical advice, and this is acceptable". This is the category that this question falls into. There is no evidence that the questioner is asking for advice on medication that they or anyone they know is actually taking. Gandalf61 (talk) 16:49, 26 January 2008 (UTC)

And one like this can easily be solved by pointing to one of the many websites which include a list of drug interactions for hydrocodone. Or just google for "hydrocodone interactions". Information != advice. --jpgordon^∇∆∇∆ 16:08, 27 January 2008 (UTC)

Moon and Sun visible at the same time

The lunar phase.

Is there a term for when both are visible in the daytime sky? —Preceding unsigned comment added by 207.141.1.129 (talk) 22:45, 25 January 2008 (UTC)

I don't think there is a specific term. That said, moon is only visible during the day at certain phases. On the diagram to the right we can see that the full moon will always rise at sunset. However the waning crescent moon is high overhead around 9:00 AM local time and visible from sunrise to around 3:00pm. The waxing crescent is overhead at 3:00 PM and visible from around 9:00 AM to sun set. The new moon could be seen all day if it wasn't for the fact that the dark side was facing us. So, If you wanted to define when the moon and the sun are both visible, you could say it is between the third and first quarter of the lunar phase. Rockpocket 08:15, 26 January 2008 (UTC)

The above response contains a number of statements that are not quite right, but which I don't feel like addressing individually. I believe it is correct that there is no specific term for when the Moon and Sun are both visible in the daytime sky, though, and that covers the question asked. --Anonymous, 21:47 UTC (daytime, but neither Moon nor Sun is visible at the moment), January 26, 2008.

Obviously my response is not accurate when describing the visibility of the sun and the moon at any given point on earth, since the earth is 3D, a sphere, and the diagram I have used to demonstrate the principle is 2D, a circle. The times will different by season, of course, and by latitude and so the definition I offer is specific only to this simplified diagram, it would differ for pretty much every point on earth. Its so kind of you, anon, to take the time to point out that there are flaws but not to specifically identify or correct them. Most helpful. Rockpocket 22:09, 26 January 2008 (UTC)

Well, the correction I'll note is your phrase "[the] moon is only visible during the day at certain phases". A better phrase, in my opinion, is "the moon is visible during portions of the day depending on the phase" -- as you go on to note, it's not that the moon is never visible during the day in one phase* and then suddenly visible during the day in the next but rather that the window of visibility changes continuously.

*Abstracting out axial tilt and what not, the moon is always above the horizon at the same time as the sun at some point during the day. At full moon, half a solar disc is on the horizon directly opposite half a lunar disc. Careful observation will certainly reveal that even first- and third-quarters aren't a practical limit; the moon is visible at significantly closer angles, though solar glare starts presenting a major obstacle. — Lomn 20:46, 27 January 2008 (UTC)

trippyfans and turkey

is it true that turkeys evolved their trippyfan acids to disable predators who tried to eat them by putting them to sleep after a large meal —Preceding unsigned comment added by 172.162.124.144 (talk) 22:46, 25 January 2008 (UTC)

That wouldn't really help the turkey. You can read about it here. Someguy1221 (talk) 23:30, 25 January 2008 (UTC)

phenogenomics

There is an institute of phenogenomics near my doctor's office in downtown Toronto. What do they study there? (email address removed) —Preceding unsigned comment added by 76.68.73.214 (talk) 23:05, 25 January 2008 (UTC)

email address removed Joe^Talk_Work 09:36, 28 January 2008 (UTC)

You mean this one?

The centre will be creating and identifying mouse models of human disease using a number of strategies with the ultimate goal of understanding how these diseases work in humans, who possess similar genes

You may be interested in model organism. Someguy1221 (talk) 23:35, 25 January 2008 (UTC)

From the description, it is a portmanteau of phenotype and genomics and is pretty much specifically meaningless. However, if you give your facility a cool, futuristic tech-driven sounding name, people tend to give you more money. Rockpocket 07:56, 26 January 2008 (UTC)

The website for the Toronto Centre for Phenogenomics is here. If you click on the 'About Us' link in the navigation menu on the left site you can get a general overview of what they do. The 'Research and Support' link will take you to a more detailed list of projects and facilities.

Per Rockpocket, phenogenomics is a portmanteau of phenotype and genomics. I gather that they're working systematically through the entire mouse genome, mutating (or knocking out) genes (the 'genomics' part) and looking to see what effect each mutation has on the mouse (the 'phenotype'). The facility is supposed to house more than a quarter million mice when in full operation. TenOfAllTrades(talk) 17:18, 26 January 2008 (UTC)

January 26

Time Travel

So say you are in the year 2100 and time travel is possible. You get in the machine (assuming that's how it will work) and come back to the present-day. Which would happen first? The future changes because you aren't there or the future changes because you affected (even minute things can change) it in the past (present-day)? This is ponderous for me but maybe not so much the science-savvy folks around here. Thanks, schyler (talk) 01:08, 26 January 2008 (UTC)

We have a quite extensive article on Time travel. Now strictly speaking, we can't actually say what would happen as the laws of physics make no explicit permission for time travel, and are often argued to prohibit it. Of course, you can always make physical predictions if you make assumptions for all those things we don't know, and one of my favorite ones (although I disagree with it) is found here. In my own personal opinion, if you displaced a person through time, even if paradoxes are assumed a non-issue, the perturbations you induce on history would be utterly catastrophic in the long term (just look at Half-Life 2!). I base this opinion mostly on the chance of a particular sperm making it into the egg, and I presume that such simple things as bumping into a guy on the street could significantly alter that. Maybe I'm wrong, though, but a difficult thing to experiment on. Someguy1221 (talk) 01:28, 26 January 2008 (UTC)

Thanks. I guess since it isn't possible there is no answer. I DO have a time machine in my room here. It only goes forward at regular speed though. It's basically a cardboard box that has the words time machine written on it. schyler (talk) 01:46, 26 January 2008 (UTC)

Really? My more advanced model reads Tim Mashin. Confusing Manifestation(Say hi!) 06:46, 26 January 2008 (UTC)

The entire concept of "changing history" with time travel comes up a lot. There are two things to consider when thinking about time travel into the past. I am going to try to condense these rather complicated topics as much as possible. You can find much more detailed information by searching for related topics on the Internet.

First, if time is continuous and there is a future, no time machine will be built that people can use to travel into our time or our future. This is based on the fact that there is no time machine available now that can do it. If one was to be invented in the future, the inventor would be popular because he or she invented a time machine. Eventually, the technology would become public and someone would travel back to a time before the time machine's invention and "invent" it to steal the popularity. Then, someone would travel to a time before that and invent it. With billions of people in the world, there will always be someone at some point in time that will travel back to an earlier time and invent time travel. Eventually, someone will travel back to 2007 and invent time travel. Since that hasn't happened, either time is not continuous (meaning the future/past doesn't exist for us) or a time machine that can travel to the present time will not be invented in the future.

Second, time is not necessarily continuous. We may exist in the present and only in the present. We remember the past, but if we travel back a day or more, we will not find our past selfs. Something entirely different will be there. We can change the past universe without having any effect on our universe. It is like jumping out of a car on the highway and landing in a car behind it. What you do in the car behind it doesn't affect the car you came from.

It is possible that neither of the previous concepts are true at all, but they both get rid of the time travel paradox issue. -- kainaw™ 12:05, 26 January 2008 (UTC)

Nothing would happen since time travel isn't possible, not even theoretically. Time doesn't exist per say, as in, a place you can go to. Time merely defines the speed at which stuff happens. Once they happened they are done, they no longer 'exist' someplace in the past. (I would edit the wormhole section of the article to correct obvious errors, but I have no sources, so it would just be reverted. Basically: moving one end of the wormhole would do one of two things: it would move the other end, so nothing useful would happen. Or it would be pointless - only mass experiences time dilation, a wormhole is not mass, it is a rift in spacetime, it would experience no dilation.)

Now, if you are simply looking for a plausible idea, my favorite is the multi worlds theory - every time you travel to the past you travel to a copy of the world. You can change whatever you like - it won't affect you, since you are from the other copy. Ariel. (talk) 08:13, 28 January 2008 (UTC)

MMR Vaccine

My child is highly allergic I understand that a MMR vaccine might be available that is not grown on "chich embryo cell cluture". My pediatrician cannot recall where or when he saw this information. Can you provide this info? Thank you, <email removed> —Preceding unsigned comment added by 24.251.164.241 (talk) 02:01, 26 January 2008 (UTC)

Hello. As far as I am aware, there is not MMR vaccine that is guaranteed free of egg protein or gelatin. Its actually gelatin hypersensitivity that causes most of the anaphylactic reactions to MMR, not egg protein. Its generally thought that the tiny amounts of egg protein are not sufficient to induce a reaction. For example, in a study of 1227 egg-allergic patients who received the MMR vaccine, only two had any symptoms suggesting an allergic reaction, and they were from the same case report, whereas in better studies no patient reacted. These combined data indicate that 99% of children who are allergic to egg can safely receive the vaccine.

That said, there is a measles-rubella combination vaccine called MoRu-Viraten that "is free of avian proteins and antibiotics, posing no risk to children with allergies to these substances." Obviously this would offer no protection against mumps, though. I don't think there is a egg-free single mumps vaccine either. Whether MoRu-Viraten is licensed for use in your locale, and whether this is appropriate for your child, we cannot say of course. You should discuss the issue further with your doctor. By the way I removed your email address for your protection from spam. Rockpocket 07:50, 26 January 2008 (UTC)

Producer Gas through fixed bed coal gasification

What is the difference between Coal Tar and Tarry residue ? Nagarajan11 —Preceding unsigned comment added by Nagarajan11 (talk • contribs) 07:06, 26 January 2008 (UTC)

In this context they are probably the same. Though 'tarry residue' could refer to anything. Coal tar is more specific.87.102.89.223 (talk) 18:21, 26 January 2008 (UTC)

Coal tar is the tarry residue produced from coal.87.102.89.223 (talk) 18:23, 26 January 2008 (UTC)

What kind of bird is this?

I took a picture of a bird at an exhibit of raptors and other birds of prey. Unfortunately, I don't have any record of the kind of bird it is. What did I take a picture of? (The exhibit was in eastern Connecticut, but I don't think the birds were all indigenous to the region.) grendel|khan 07:08, 26 January 2008 (UTC)

Looks a lot like one of my favourite birds - the Kestrel. Grutness...wha? 07:54, 26 January 2008 (UTC)

My favourite bird - the Great Black-backed Gull can easily defeat your favourite bird in combat. I've seen it happen a couple of times now. The GBBGs don't much like Kestrels hovering in the sky over their nesting areas. --Kurt Shaped Box (talk) 18:12, 26 January 2008 (UTC)

I don't suppose you can identify which species it is? I like to tag things as specifically as possible. grendel|khan 18:44, 26 January 2008 (UTC)

Assuming it is a bird native to North America, it is a Merlin of the Prairie subspecies. Merlins are a type of falcon, similar to Kestrels, but slightly larger.--Eriastrum (talk) 19:59, 26 January 2008 (UTC)

Do we want experiment pages?

Does wikipedia want pages for experiments, such as the spouting can, or ball and hoop, or are they considered non-notable? Thanks --Dvorak (wtkwhite) ^(Talk) 10:45, 26 January 2008 (UTC)

If you can find references that denote notability, then it is notable. The big problem with notability is that many articles make no attempt to show notability. If you can find references to claim notability, then editors can discuss the merits of the topic on the article's talk page. -- kainaw™ 11:55, 26 January 2008 (UTC)

I believe that many pages of wikipedia should actually be in wikionary, wikibooks or wikiversity. I don't understand why some people are so pushy to include everything into wikipedia. It would be much easier to navigate all these sites if different kinds of information were on the appropriate place. Mr.K. (talk) 14:41, 26 January 2008 (UTC)

I find it much harder to navigate across several sites - put it all in one place works best for me. DuncanHill (talk) 17:42, 26 January 2008 (UTC)

Bright object in the sky last night...

I saw a bright object in the sky last night, no it wasnt a UFO, I am just interested if there was anything signifcantly astronomical happening last night? I live in South East England and the night sky was partiuarly clear. It didnt move all night, so no it wasnt a plane. Thanks RobertsZ (talk) 12:49, 26 January 2008 (UTC)

I know that the planet Venus can been seen from Earth, see this. I might also haven been a satellite. They can often be seen orbiting from Earth, but you'd have to check your time and location. Try this and this to see if you can match one to your location. Think outside the box 14:45, 26 January 2008 (UTC)

Mars and Jupiter are both visible in the night sky at present. (I think Venus doesn't rise during the hours of darkness at present) If you know your constellations, well, Orion, Mars is 'above' Orion at about midnight. Across to the left a fair way the other bright 'star' is Jupiter. I'm sure there are technical terms for these directions but hey, I think you'll see what I'm pointing at! If you want to know a little more try [8], sign up, and have a look around Richard Avery (talk) 16:37, 26 January 2008 (UTC)

Ahhh, i didnt look at the stars around the bright object, i just thought 'oh thats bright' and didnt think much more of it, untill reading earlier this morning about that asteroid passing close to the earth(loads of paranoid hype). I guess its probably a planet then? If so will it be equally visible tonight? I will look in more detail and see where it is in relation to other selestial points. Thanks for the replies so far RobertsZ (talk) 16:47, 26 January 2008 (UTC)

Mars is very bright right now and is visible in the east after sunset and high in the sky later at night. It is slightly yellowish or reddish. Venus is also very bright right now, but is visible only low in the east just before sunrise. Jupiter is not too far from Venus, but not as bright. An asteroid would probably not be easily visible until just before it hits us. So I hope you didn't see an asteroid.!--Eriastrum (talk) 19:53, 26 January 2008 (UTC)

If it was moving rather than stationary, it could well have been a satellite flare from an iridium satellite, or could even have been the International Space Station, which is easily seen making its slow graceful passes across the sky. Grutness...wha? 19:57, 26 January 2008 (UTC)

Ah skip that - I didn't notice that you said it didn't move. Grutness...wha? 19:58, 26 January 2008 (UTC)

Well it wasnt moving noticably, it may have progressed across the sky slowly, how quickly do objects orbiting the Earth move? (I will have a look outside in a minute, see if its there again) RobertsZ (talk) 20:19, 26 January 2008 (UTC)

Nope, it isnt there tonight, but I cant see any stars either, I guess there is too much light pollution at the moment, no one has gone to bed, there isnt much cloud cover, look like i will be late night staregazing . RobertsZ (talk) 20:24, 26 January 2008 (UTC)

They're slow but move noticeably, about the speed of a distant aircraft. Grutness...wha? 20:34, 26 January 2008 (UTC)

Most satellites are in one of two types of orbit. One is low Earth orbit, which is used because it's the cheapest to achieve has the shortest communication distances. LEO satellites make a complete orbit around the Earth in under 2 hours, so if you see them from a particular place, they will move noticeably in a few minutes, like a distant airplane. The Iridium satellites are of this type.

The second type is a geostationary orbit, or Clarke orbit, which is used because, when seen from the ground, the satellite remains in a fixed location at all times, day and night — which allows communications (TV, telephone, etc.) to be received by an antenna that does not move. I'm not sure if there are any satellites in Clarke orbit that can be seen from the ground, but there certainly aren't any that are seen as bright objects. It's too far away.

Planets, on the other hand, rise and set in the same manner as the Sun, the Moon, and the (non-circumpolar) stars. Which is to say, they move in an arc from a point on the eastern horizon to a point on the western horizon, such that a north-south line bisects the angle between the two points. Because all the planets' orbits are in similar planes, they all follow more or less the same path in the sky that the Sun does from sunrise to sunset. Their positions change all the time — that's why they're called planets — but not so much that you'd notice from one night to the next, unless you compared the position of the planet with another nearby object.

Mercury and Venus have orbits inside the Earth's orbit, so they always stay fairly near the Sun. If you see something in the sky "all night", then it's not Venus. (Incidentally, Venus is bright enough to see in the daytime sky, if you know where to look, at times when it's not too near the Sun.)

For the other planets, the Earth's orbit is inside theirs, which means they can appear at any position along the Sun's path. Currently Mars is fairly near its opposition, the time when it is directly oppposite the Sun and also closest to Earth. Jupiter, on the other hand, is in almost the opposite direction. (In fact, Venus and Jupiter should be visibly close together just before sunrise now -- I haven't checked this myself -- and moving closer together in the sky. On the morning of February 1st they will be less than a degree apart, before they start moving apart again.)

Conclusion: either you saw a star, or you saw Mars. Since you noticed it, it's probably something that isn't there all the time, and therefore Mars. It should indeed be visible on subsequent nights.

--Anonymous, 22:20 UTC, January 26, 2008 (links edited later).

I think we can safely assume that there is currently no geostationary satellite visible to the naked eye. The ISS - the brightest satellite (except Iridium flares) - is visible at magnitude 0 at 1000 km distance and 50% illumination according to Heavens-Above. That makes magnitude 7 at a geostationary distance and 100% illumination. Icek (talk) 00:14, 27 January 2008 (UTC)

Hmm... with the "maximum brightness" from Hevanes-Above I get magnitude 5.3 at geostationary distance instead (it seems like 50% illuminated means 11% illuminated) - but the ISS is way larger than any current geostationary satellite - the data for e. g. Genesis I says that it's about 5 magnitudes dimmer than the ISS. Icek (talk) 00:24, 27 January 2008 (UTC)

Isn't that the satellite that lost power and is closing in on earth for the end of feb ? Mion (talk) 07:59, 27 January 2008 (UTC)

No, Genesis I is a satellite of Bigelow Aerospace. The satellite that "lost power" is a US spy satellite. I don't have detailed information about what happened to that spy satellite or even what its orbit is (but I haven't searched the internet for that information so far), but apparently they have lost control of it - either it would have crashed anyway, but in a controlled way, or they lowered the perigee for better observations and planned to raise it again, but now they cannot (air resistance decelerates the satellite so that it eventually deorbits - see orbital decay for details). Icek (talk) 13:26, 28 January 2008 (UTC)

Setting toaster timer: stand by...

If the toaster is set to low, I put my bread in, initiate the toasting sequence and then raise the toasting level, is the toasting timer reset to the longer period? What if the toasting sequence is nearing completion (say, 90%) and then I reset the timer to 50% of the initial toasting magnitude; will the total toasting equal 140%? ----Seans Potato Business 13:09, 26 January 2008 (UTC)

That depends entirely on the construction of your toaster. I think old-fashioned toasters work with a bimetal mechanical spring/catch mechanism. They should actually toast until a certain temperature has been reached (at the spring, not necessarily at the toast). But for modern electronically controlled toasters, everything goes. --Stephan Schulz (talk) 14:20, 26 January 2008 (UTC)

This is a surprisingly deep question. Stephan is right; every toaster is different. And even if we knew how your toaster was constructed, it would be very easy for our RDesque armchair speculation to come up with an entirely wrong answer. So if you really care about this question: experiment! See how long the toaster toasts at various settings, without switching settings in mid-stream. See if it makes a difference whether there's bread in the toaster or not. See if it makes a difference whether the toaster is hot or cold -- I've found that the second piece of toast toasted at the same setting often comes out differently than the first one. Finally, with that preliminary data in hand, begin performing experiments where you vary the setting partway through the toasting cycle, as in your original question.

Keep good notes. Develop hypotheses -- educated guesses -- about what will happen, and refine your experiments to test those hypotheses. Develop theories about how the toaster works, and see if your experiments can confirm or refute those theories. This could end up being an excellent educational application of the scientific method. —Steve Summit (talk) 15:36, 26 January 2008 (UTC)

I've wondered about this too. I think the simplest clock that would be used (and thus also the most likely) is a capacitor resistor circuit, or a digital clock circuit. The toast is done when the capacitor is charged (or discharged). So changing the dial is changing the variable resistor, and will affect the future speed at which the capacitor charges, but will not affect how much it charged so far. A digital clock circuit would act much the same way - moving the resistor changes how fast the clock runs down. But it would not affect how much it ran down so far. Ariel. (talk) 08:27, 28 January 2008 (UTC)

cheap scientific tools

I am searching for cheap scientific tools that can be used within a high-school environment. Something under $1,000, perhaps some tool that can analyse small things (like crystals and the like). PC is provided, if the tool need to be connected to one.

Can you recommend some? Mr.K. (talk) 14:57, 26 January 2008 (UTC)

I'm not sure exactly what sort of equipment you're looking for, but American Science and Surplus often has good deals on lab equipment. APL (talk) 20:03, 26 January 2008 (UTC)

The American Science and Surplus is surely in the right direction. Mr.K. (talk) 20:40, 26 January 2008 (UTC)

Dammit, why do they have to be American? Anything similar in Britain? DuncanHill (talk) 12:34, 27 January 2008 (UTC)

Are RGY and RYB monitors possible?

http://en.wikipedia.org/wiki/Color_wheel

In my learning about color perception I've come across the opponent process theory of color which posits 3 color channels: red-green, blue-yellow, and luminance.

I understand that computer monitors represent color by varying amounts of Red, Green, and Blue (RGB) for each pixel. Since we have a blue-yellow color channel, would it be possible to create a Red, Green and Yellow (RGY) computer monitor?

following this same logic, would a Red, Yellow, and Blue (RYB) monitor be possible as well?

Thank you!

Mark465 (talk) 15:09, 26 January 2008 (UTC)

Marcus Cowgill

You could produce such a monitor with any combination of colors as primaries and whatever combination of colors you choose some colors the human eye can see will be unrepresentable. But some combinations of primaries can cover a much larger part of the human eyes visual range than others. A correctly chosen red green and blue are about the best we can do with three primaries. In particular with your red yellow and blue system it would be impossible to mix white. Plugwash (talk) 15:21, 26 January 2008 (UTC)

See color space. Mixing colors only gives you a limited number of colors. Picking the wrong colors means you won't be able to represent certain colors. Don't confuse the physiology of color processing with the physics of color mixing—they're not the same thing. --24.147.69.31 (talk) 16:34, 26 January 2008 (UTC)

Returning to the original question, sure, you could design the signalling between the video generator and the monitor to use any number of different encodings. RGB came to dominance simply because it was a direct representation of what was actually happening at the electron guns of the cathode ray tube and the phosphor dots on the screen so it made for the simplest electronic circuits back in the days when this stuff was done with stone knives and bearskins. But note that component video typically used in home video uses a different encoding: YPbPr. You might also enjoy our article about gamut.

Atlant (talk) 17:38, 26 January 2008 (UTC)

You can easily determine the gamut of colors reproducible with given primaries by looking at Image:CIExy1931.svg. Simply form a triangle with the three primaries as vertices. You can recreate the color with those primaries if and only if it is inside the triangle. So we see that RGB is a good choice because that triangle covers most possible colors. RGY is an awful choice because that triangle is very narrow, almost degenerate. It is impossible to create blue or white from red, green, and yellow. RYB is not so bad, but you still can't get most shades of green. —Keenan Pepper 19:06, 26 January 2008 (UTC)

What Keenan said. I recommend David Madore's writing about Colors. – b_jonas —Preceding comment was added at 08:48, 28 January 2008 (UTC)

Highest village in Tibet

What is the village with the highest altitude in Tibet? Most sources give different information, and there doesn't seem to be any note of it on Wikipedia (besides the altitudes in individual village articles). - Super Sam ^{ultra quick reply} 16:55, 26 January 2008 (UTC)

It's impossible to answer that sort of question, unless you define how many dwellings constitute a village, how close together they would have to be, etc. Also most people living at high altitude do so on a seasonal basis, so would you include yurts and tents? Even then, Tibetan society is much more loosely structured than the Chinese would have us believe. I wouldn't trust any statistics supplied by Chinese sources.--Shantavira|^{feed me} 09:03, 27 January 2008 (UTC)

Sykeds ?

I was watching a gardening show and they talked about planting "sykeds", an endangered tree similar to palm trees. They didn't spell it for me and I've never heard the term before, so have no idea how it's spelled. What is the correct spelling and do we have an article on them ? StuRat (talk) 18:29, 26 January 2008 (UTC)

I believe you may be referring to cycads. grendel|khan 18:42, 26 January 2008 (UTC)

Yes, that's it. Thanks, StuRat (talk) 19:33, 26 January 2008 (UTC)

Reason for lack of sense of time - i.e.: thinking it's years ago?

I read the articles on time and sense of time and understand a little better, but still, my great-aunt had a stroke a while back and for a while as she recovered she would swear it was 1955; yet she knew her daughter (who would have been maybe a 5-year-old adoptee then) and others. I'm thinking that some part of her mind had been blocked (she's better now), a part that had registered what year it was. Is that accurate? Also, another oddity which I've heard is related to Asperger's Syndrome in some people is that they will think this without any impairment such as a stroke; not often, but they might think they're in antoher time; is this accurate? Is it because of the eidetic memory and how they recall things with all the sights, sounds, and everything so specifically? Or, don't those with AS really have this happen?Somebody or his brother (talk) 21:18, 26 January 2008 (UTC)

Ribot's Law and retrograde amnesia may be of some interest. Serious cases can have people believe they are living in the past, but general dementia or psychological regression might also be involved. MilesAgain (talk) 20:01, 27 January 2008 (UTC)

Thanks; sounds like just dementia, as just her placement of the date was faulty and she knew her daughter was her daughter, rather than thinking her daughter should be about 5 years old, whereas in retrograde amnesia everything shifts back to that date, if I'm understandingit right. —Preceding unsigned comment added by DTF955 (talk • contribs) 21:27, 28 January 2008 (UTC)

pyro

im making my own pyro vidos have any ideas? —Preceding unsigned comment added by 76.14.124.175 (talk) 21:42, 26 January 2008 (UTC)

Buy life insurance?

Atlant (talk) 22:00, 26 January 2008 (UTC)

Don't? Paragon12321 (talk) 23:10, 26 January 2008 (UTC)

I mean for the videos. like wat should i put in them? have any good pyro tricks? —Preceding unsigned comment added by 76.14.124.175 (talk) 04:10, 27 January 2008 (UTC)

For some ideas on what NOT to do take a look at the discussion on #Firing flare guns at people above. SpinningSpark 16:07, 27 January 2008 (UTC)

Do it in a video game. --f f r o t h 16:11, 27 January 2008 (UTC)

You don't think you're going about this rather backwards? Don't such videos usually get created when someone thinks of something or does something and says "Wow, that would make a great video."? You question strikes me like someone asking "I want to write a book, what should I write it about?" APL (talk) 23:58, 27 January 2008 (UTC)

Sitting too close to TV

Is it really harmful to sit "too close" to the television? Would the same thing apply to computer monitor screens, given differences between their use (difference also between CRT vs LCD?)? ----Seans Potato Business 22:10, 26 January 2008 (UTC)

[9] ----Seans Potato Business 22:59, 26 January 2008 (UTC)

In short, "no". I don't agree with some of the material used in the Straight Dope answer above. The thing to keep in mind (as SD mentions) is that sitting too close to the TV might lead to eye fatigue (which is usually a transitory problem relieved by switching off the boob tube and doing something else), but not to myopia, which is (largely) genetically determined. I only add the (largely) in there because some kinds of injury can mimic the effects. Matt Deres (talk) 20:11, 28 January 2008 (UTC)

Thermochemical tables

hello can you tell me where can i find on the internet some accessible thermochemical tables containing data such as enthropy and enthalpy of formation, of reaction?(on the page "thermochemical equation" there is a link to ΔH tables, but it doesn't work)

can you also tell me if it's possible, and how, to find Active Thermochemical Tables (ATcT) online?

thank you 82.60.0.232 (talk) 22:43, 26 January 2008 (UTC)

NIST Chemistry Webbook http://webbook.nist.gov/chemistry/ —Preceding unsigned comment added by Shniken1 (talk • contribs) 05:18, 27 January 2008 (UTC)

Malonic acid

Just how concentrated is it in apples? Could one get a useful yield from a bushel of apples, or would it be significantly (>50% higher yield) more useful to just preform a synthesis? Yamakiri ^T_C § 01-26-2008 • 23:11:37

I would not be so much worried about the content of it as I would be worried about how exactly one would extract it. For obvious reasons, it would be hard to chemically differentiate it from, say citric acid or malic acid or succinic acid. —Preceding unsigned comment added by 18.96.6.239 (talk) 02:10, 27 January 2008 (UTC)

RC Copter Problem

I got a Small RC Helicopter for Christmas from my friend (A knock-off of the Picoo Z). It worked fine out of the box after I adjusted the (electronic) trim. But on it's 3rd flight it started spinning uncontrollably in a counter-clockwise fashion. The tail rotor is spinning fine, and for the first 30 seconds of flight after charging the helicopter flies straight, only to go nuts every time I try to fly any time after wards. Does anyone have any idea how to fix this? I try adjusting the trim, but that doesn't work. I have no clue what to do now Chris16447 (talk) 23:29, 26 January 2008 (UTC)

• Two rotors on top, right? Make sure both of them are firmly seated on their axles (or whatever you call that part.) When mine crashes (or even lands a little hard), the bottom one ends up loose on its axis, and it just freely rotates rather than turning in a powered fashion, resulting in spin spin spin. --jpgordon^∇∆∇∆ 16:02, 27 January 2008 (UTC)

January 27

Summer Solstice

In the eleventh century what was the date for the summer solstice? Is it correct that the summer solstice swings between the dates of June 20 and June 24 over thousands of year? When (century) was the summer solstice June 24 (Midsummer's Day)? --Doug ^talk 00:15, 27 January 2008 (UTC)

see this calculator. Remember to convert the Gregorian result to a Julian date. - Nunh-huh 02:12, 27 January 2008 (UTC)

Cross breeding of rats and squirrels

Is it possible for rats and squirrels to crossbreed? I know they are different species, but there are cases of different species breeding (the mule being the most obvious). Also, in general, what are the requirements for species being able to interbreed? --Evan Seeds (talk)(contrib.) 03:28, 27 January 2008 (UTC)

The more closely the species are related, the more likelihood of success. If the species have recently diverged, it's more likely that they have a similar number of chromosomes, and it's more likely that their offspring won't suffer from a fatal lack (or surfeit) of genetic material. Horses have 32 pairs of chromosomes, while donkeys have 31 pairs, and the species have recently diverged: they both belong to the same genus. Rats have 20 pairs of chromosomes, while squirrels have 27 pairs, and have diverged far more: they both belong to the same order (Rodentia), but different families as well as different genuses. - Nunh-huh 03:43, 27 January 2008 (UTC)

Furthermore, even within the family Muridae the diversity is astonishing. Quoting from Nakamura et.al. :

the diploid chromosome numbers (of Muridae) range from 2n = 10 in Akodon species ... to 2n = 102 in Tympanoctomys barrerae.

Cheers, Dr_Dima. —Preceding comment was added at 15:53, 27 January 2008 (UTC)

I don't think that's too surprising. Rodents were the first mammals to evolve and have relatively short lives and breed a lot. As a consequence you'd expect a lot more evolutionary diversity there than in horses and the like, which are relatively recent and live relatively long lives. --24.147.69.31 (talk) 03:28, 28 January 2008 (UTC)

Strictly speaking, "Rodents were the first mammals to evolve" is nonsense: all mammals are equally descended from "the first mammals to evolve". I assume .31 means that the first mammals resemble today's rodents more than they resemble other orders. —Tamfang (talk) 23:16, 28 January 2008 (UTC)

Medical one way material

Im looking for the corrct english name for "medical one way material" (german: medizinisches Einwegmaterial). For instance most Scalpels, plastic stuff or medical syringes are made for one-way use only. I want to create this category in Commons. Is there an english article in Wikipedia about "medical one way material"? --84.137.47.124 (talk) 13:55, 27 January 2008 (UTC)

Probably "single use item" or "disposable item". -- Finlay McWalter | Talk 14:09, 27 January 2008 (UTC)

I think "disposable medical products" will do best. (most google-hits) Thanks! --84.137.47.124 (talk) 15:05, 27 January 2008 (UTC)

I think "single-use item" (with a hyphen, please) is much better. It conveys the fact that you aren't intended to use it more than once. An item that you use a few times and then discard, like a razor blade, is also "disposable". --Anonymous, 23:47 UTC, January 27, 2008.

Inhaler dream

Last night (in a dream) I was standing around in the ocean maybe 100 yards out (it was shallow) with friends I've never seen before. We had a gigantic inflatable raft that everyone was sitting on in deck chairs. One guy had asthma and kept coughing and using his inhaler. Someone splashed him from the water and his inhaler got a little wet. It started hissing a little.. he shrugged, capped it, and put it back in his pocket, then we all went in the water. The inhaler got totally wet and he pulled it out to use it I guess but foam was now pouring out of it. I shouted nooooooooo and dove for it in slow motion, grabbed it, and reached back to throw it, but someone grabbed my wrist and said hey dude not cool give it back to him. I shook off his hand and managed to toss it but he batted my hand and it only went a few yards. The asthmatic guy realized what was going on and dove in slow motion between me and where the inhaler hit the water. As soon as he came between me and it, there was a deep thump in the water and I could feel feet of water rushing past my legs. His eyes crossed in pain and an instant later, a mountain of boiling steam erupted from the ocean behind him. It was a few yards across and a lot higher than wide. He was blown forward and landed right in front of me, then I woke up. How much volume of gas is actually in one of these inhalers?! -froth —Preceding unsigned comment added by Froth (talk • contribs) 16:09, 27 January 2008 (UTC)

Metered dose inhalers usually contain a small amount of medication dissolved in a haloalkane. When full, the canister is completely filled with liquid haloalkane, and thus the volume of gas in the inhaler is about zero. When the inhaler is depleted, it will be filled with the haloalkane gas (at a much lower pressure) or air (depending on the valve mechanism), with a volume equal to the volume of the space in the inhaler bottle, I would guess around 25cc. Hopefully someone will come along shortly and be able to tell you the volume of gas at atmospheric pressure which is created from the volume of liquid in an inhaler, as that is probably what you are looking for, but until then, the answer to your question as stated would be somewhere between zero and the volume of the canister. Tuckerekcut (talk) 18:15, 27 January 2008 (UTC)

So no real explosive potential or catastrophic reactions with salt water? --f f r o t h 18:27, 27 January 2008 (UTC)

Well, Trifluoromonofluoroethane and Heptafluoropropane, two propellants used in inhalers, have vapor pressures of 70 and 44 psig, respectively, at room temperature. So a tiny amount of gas will build up inside the container until this pressure is reached. Suffice it to say I wouldn't want to puncture an aluminum can at 70psi anywhere near my face, but such a small volume of gas, and such a small mass of possible shrapnel is unlikely to do impressive damage, in my unproven and nearly anonymous opinion. Tuckerekcut (talk) 19:07, 27 January 2008 (UTC)

(Returning to a theme of a few weeks ago), in the process of "safing" inhalers so that I could recycle the aluminum canisters, I've punctured them with an automatic center punch; nothing exciting happens. (And yes, they still contained some of the propellant in liquid form so they were still in equilibrium at full pressure.) The canisters appear to be quite strong compared to the pressure involved, so a small puncture doesn't cause a catastrophic "tear-out" of the can.

Atlant (talk) 21:06, 27 January 2008 (UTC)

Once I managed to get an inhaler into the clothes dryer. The heat caused the gas to build up enough pressure to push the concave bottom of the canister into a convex bulge, so they aren't completely invincible. HYENASTE 03:11, 28 January 2008 (UTC)

Ideal tax rate

Obviously, it can't be 100% as no money would be left for private industry, and obviously it can't be 0% as that would leave no money for public education, roads, airports, seaports, fire departments, police departments, etc.; thus providing no infrastructure for a growing economy. My question, then, is what is the ideal tax rate for maximum growth of the economy ? I realize this is a very difficult question to answer. I would expect that a chart correlating various net tax rates and long term growth rates in countries around the world could go a long way toward answering this question. Perhaps the net tax rate could be found by dividing the total of all taxes collected by national, provincial, and local governments in a country for a year by the annual national product. Do we have any such chart ? StuRat (talk) 17:28, 27 January 2008 (UTC)

Wouldn't the ideal rate depend on your personal or your nation's economic philosophy? Probably the lower it is, the higher the growth rate; the problem is (as you pointed out} providing public goods with a very low tax rate. Some of these things could theoretically be provided privately. I don't see why airports and seaports, for example, couldn't be owned and run by airlines/shipping lines (or a group of airlines/shipping lins owning shares). (It would probably raise prices, though...) Vultur (talk) 18:17, 27 January 2008 (UTC)

It definitely depends on the economic philosophy. As a libertarian, I think taxes should be as low as possible, and that most of the things on your list shouldn't be run by the government. Education should be privatized, and roads should be privately owned and maintained, as well as airports and seaports. (I also disagree with Vultur's prediction that this would raise prices. Competition in the market usually decreases prices in the long run.)

Also, I disagree with your (StuRat's) unquestioned use of "growth of the economy" as a figure of merit. A nation shouldn't be judged by its total size or wealth, but by the freedoms and quality of life enjoyed by its citizens. Growth isn't always good. (See VHEMT for another example of this philosophy that may surprising you.) Just some things to think about... —Keenan Pepper 19:16, 27 January 2008 (UTC)

I can't agree that lower tax rates are always better, which means 0% is ideal. That means no public education, which inevitably results in large portions of the population being ignorant and condemned to lives of poverty. This isn't just bad for them, it's bad for the economy of the country as well. StuRat (talk) 03:41, 28 January 2008 (UTC)

Tocqueville commented on the high degree of literacy, and appetite for books, among Americans a generation before the movement for public schooling (which is not the same thing as education) really got going. We might also observe the large portions of the population who are ignorant and condemned to poverty with public schooling. Like almost everything else on your list, education was done privately long before government stepped in and told us that it can't be done privately. —Tamfang (talk) 23:13, 28 January 2008 (UTC)

0% works pretty well in Snow Crash and roads still get built and children still go to school --f f r o t h 19:55, 27 January 2008 (UTC)

Yes: Laffer curve. The details, e.g., progressivity and the needs of government such as war or a retiring population -- seem to be much more important than the average rate. MilesAgain (talk) 20:06, 27 January 2008 (UTC)

That seems to be the correct article, thanks. However, they only talk about it in theory, no actual numbers are provided. Certainly somebody could come up with some approximation of the ideal tax rate (10% or 90% ?). StuRat (talk) 03:41, 28 January 2008 (UTC)

Over at Laffer curve I found an excellent summary of any discussion on an ideal tas rate: here. --Ouro (blah blah) 14:55, 28 January 2008 (UTC)

Exactly; as I said, the percentage number is not as important as the other factors determining the ideal rate. Under some conditions, 1% may be ideal, but under others, 50% could be best. 20% could be good under progressive tax tables, but bad under a flat tax, all other things being equal. MilesAgain (talk) 19:32, 28 January 2008 (UTC)

Mesozoic bird taxonomy

I'm having trouble finding out what family, if any, Paraprotopteryx is in. I'm working on the article for this genus now. It appears to be incertae sedis, but can someone confirm this? Vultur (talk) 18:18, 27 January 2008 (UTC)

Not much on google, is there? Found a wiki confirmation here[10] in the section Avian incertae sedis in the List of fossil birds. Julia Rossi (talk) 03:52, 28 January 2008 (UTC)

Fossils from mountains and islands

Sorry to ask two paleontology questions in succession, but is it true that mountains and small islands such as atolls have left no fossils, so we don't know what the Mesozoic mountain species were? Vultur (talk) 18:20, 27 January 2008 (UTC) —Preceding unsigned comment added by Vultur (talk • contribs) 18:19, 27 January 2008 (UTC)

Think about where there could have been rocks formed on a mountain. Most rocks are formed in hollows like lakes, rivers, oceans. Perhaps there are some fossils preserved under volcanic lava flows. Recent atolls are likely to have coral fossils, but mountain species are not likely to live on an atoll. Graeme Bartlett (talk) 21:20, 27 January 2008 (UTC)

Sorry, the atolls were a separate question. I read a book called "Life: The First Four Billion Years" where the author said that any islands in Panthalassa, when Pangaea was around, left no fossils or rocks at all - anything could have been there. I was asking how accurate that was. 98.199.17.94 (talk) 22:55, 27 January 2008 (UTC)

Isolated atolls on the ocean floor move around on the oceanic plate. Ususally oceanic crust is swallowed up in a subduction zone in a oceanic trench. This is broought down to great depths and usually melted to form magma. Fossils do not survive this treatement. It is possible for seamountains to be accreated to the side of a continental margin. But I don't know if any have done this from the Mesozoic or not. And if they did whether there were fossils. Graeme Bartlett (talk) 23:12, 27 January 2008 (UTC)

Big flashes of flame while cooking

When people are cooking something in a pan, probably mixing it around everything, and they make those big flashes of flame, what's going on? Where is the flame coming from? What's the purpose and how do I copy it? Does it have a name? ----Seans Potato Business 18:29, 27 January 2008 (UTC)

I think you mean Flambé. Hope this helps. --Dr Dima (talk) 18:40, 27 January 2008 (UTC)

In general add a liquid containing alot of alcohol and let the alcohol boil of - it then ignites - you need a gas stove to do this (or a match)

The alternative is flashes from very hot oil - such as can be obtained when stir frying - it's the same sort of thing - oil vapour is igniting - it needs to be very hot - and sometimes a lid is needed to put the fire out..77.86.108.68 (talk) 18:54, 27 January 2008 (UTC)

If Sean is thinking of stir frying, as in Chinese and Thai cooking, the flashes are definitely burning oil, not alcohol (i.e. not flambé). Alcohol (in cooking, at least) generally burns blue, slowly, and relatively cool, while oil flashing to vapor and burning is generally more yellow, quick, and hot. Also, flambé is a very deliberate, show-off technique, which is rarely done in the kitchen, rather right at the table in front of the consumer. (If you're going to add an expensive liqueur to a dish and then burn most of it right back off, you don't want to waste the effect, since the effect is all there is.) —Steve Summit (talk) 19:30, 27 January 2008 (UTC)

I'm thinking of the Chinese/Thai oil stuff. --Seans Potato Business 19:36, 27 January 2008 (UTC)

Get the oil very hot - then move the pan about like you are a proper chef maybe tilt it a bit - you really need gas - hopefully the oil will ignite.. if the oil is really hot so that it's spitting you may burn your eyebrows off etc. As I said before having a lid ready to put it out is a good idea. Also as far as I know it's not intentional and doesn't really add the the taste - just a hazard involved with cooking with very hot oil..83.100.183.193 (talk) 20:53, 27 January 2008 (UTC)

Flambé isn't just for show. Cooking that uses alcoholic beverages for deglazing the pan will often end with the flaring-off of the alcohol portion and the ignition is usually deliberate.

Atlant (talk) 21:11, 27 January 2008 (UTC)

Danger of collecting blood samples for experiment

In such a case where one is collecting blood samples from the general population, there is surely a risk (to all parties concerned but I'm not addressing that right now) to the person collecting blood. Why then is not justified that they wear a mouthmask and safety glasses to protect their mucosal surfaces? How small is the risk? ----Seans Potato Business 19:34, 27 January 2008 (UTC)

As long as the vials of blood remain intact, there's no way for blood to get from the patient onto the mucosal surfaces of the phlebotomist. During the blood draw, blood is contained by the steel needle and then in the glass vials. In principle, it would be possible for a small amount of blood to be aerosolized if a vial were dropped and smashed, and for a small amount of that aerosol to settle on the mucosa of the phlebotomist. Similar aerosolization could occur if the phlebotomist were to fling blood-contaminated equipment about in the air. (The latter is an unlikely thing to have happen, and suggests a neglect of other basic safety precautions....)

Note that unless the blood is agitated to generate pathogen-laden aerosols, there is no risk from standing blood or blood droplets. (Clinicians and experimenters who handle pathogenic materials are – or ought to be – trained in techniques that minimize aerosol creation during the course of their tests.) Viruses, bacteria, and parasites won't evaporate, and won't travel through the air without help. Only small, non-infectious molecules (mostly water) will enter the air spontaneously by evaporation.

In short, aerosolization of blood during phlebotomy is very rare in the first place, and even where it does occur only small amounts of blood (and and correspondingly small load of pathogens) will be aerosolized. Of that pathogenic aerosolized material, only a vanishingly small fraction is likely to settle on a phlebotomist's mucosa. Many blood-borne pathogens – including many of the nasty ones like HIV and hepatitis C – are very ineffective at infection across healthy mucosa. Finally, in drawing blood from a general (superficially healthy) population for research purposes, the likelihood of the blood carrying any serious disease is quite small. The cost, inconvenience, and/or discomfort of masks and glasses aren't generally seen as a worthwhile tradeoff to defend against an extraordinarily tiny risk. Greater precautions may be taken in drawing blood from patients with known serious diseases or serious and unexplained symptoms. TenOfAllTrades(talk) 20:46, 27 January 2008 (UTC)

Okay, thanks for that explanation; but what about gloves and does it matter what material the gloves are made from? Are some more resistant to puncture than others? --Seans Potato Business 21:33, 27 January 2008 (UTC)

Generally the flimsy gloves used by clinicians aren't going to make a whit of difference if they're handling sharps incorrectly. Needles and broken glass are sharp; they'll easily go right through both nitrile and latex gloves. Individuals who work with biohazardous sharps are (or should be) trained in proper handling techniques. (Never recap needles; don't pick up broken glass with your hands; etc.) Intact gloves (nitrile and latex are the most common types) are all quite adequate for protecting individuals from bodily fluids. Different brands of gloves will have modest differences in stretchiness, comfort, fit, and durability. TenOfAllTrades(talk) 17:45, 28 January 2008 (UTC)

Glaciers

Are glaciers geological features? You might think this is for homework, but no. I did a science mind map two months ago and never figured out this question. Please reply. I would greatly appriecate it. 99.248.42.43 (talk) 20:19, 27 January 2008 (UTC)

The answer probably depends on your definitions. Most people would agree that a geologic feature needs a degree of permanence to it. Glaciers tend to stick around quite a while by human standards, but ice ages bear testament to the mutability of glaciers. Additionally, the current state of widespread glacier retreat may impact your decision. — Lomn 20:29, 27 January 2008 (UTC)

However, the Morraines left behind by glaciers are most definitely a feature of the geological record. SpinningSpark 23:50, 27 January 2008 (UTC)

If "geological feature" means something that people in the field of Geology study, then sure -- glaciers are definitely studied by geologists. But then glaciers are also studied by people in other fields, like Climatology, so maybe they are "climatological features"? Then again, Glaciology is the study of glaciers, which would make glaciers "glaciological features". Maybe the nature of something like a glacier depends on what framework you are working with. Just a thought. Pfly (talk) 03:53, 28 January 2008 (UTC)

Prehistoric love

I'd like to know more about this [11] archaeological finding. Thanks. --Taraborn (talk) 20:38, 27 January 2008 (UTC)

A bit more context such as where/when may help getting you a detailed answer.. if you can provide it. (Otherwise those two 'things' are skeletons - the inorganic remains of human beings in what is often called a 'dual burial').83.100.183.193 (talk) 20:58, 27 January 2008 (UTC)

[12], ,this one ? Mion (talk) 21:25, 27 January 2008 (UTC)

Yeah, that one. Thanks. --Taraborn (talk) 22:01, 27 January 2008 (UTC)

What do dogs search for?

When a dog walks around searching for exactly the right place to do its business, what is it really searching for? —Preceding unsigned comment added by 216.47.188.16 (talk) 21:28, 27 January 2008 (UTC)

As I understand it they are smelling around for scents and finding a place to 'mark their territory'. See here (http://www.hsus.org/pets/pet_care/our_pets_for_life_program/cat_behavior_tip_sheets/urinemarking_behavior.html) and here (http://home.howstuffworks.com/how-to-solve-dog-behavioral-problems10.htm) ny156uk (talk) 22:41, 27 January 2008 (UTC)

Does that mean if they do it in the wrong place that it may send the wrong signal and start a fight? —Preceding unsigned comment added by 71.100.3.254 (talk) 13:33, 28 January 2008 (UTC)

From what I know, yeah. If two dogs' territories overlap or border, or one starts marking an other dog's territory as his own, and the dogs perceive themselves (via this smell communication) as hostile, then they bark and growl at each other, and do who knows what else. There used to be a term for this olfactory communication, but I forgot it. --Ouro (blah blah) 14:50, 28 January 2008 (UTC)

Calendar calculation

Taking into account the changes from the Julian calendar to the Gregorian calendar what would the date as we know today as June 16 be in the 14th century in Europe?--Doug ^talk 21:51, 27 January 2008 (UTC)

June 16th (Gregorian) = June 8th (Julian) in the 14th century (not including 1400, when it's June 7th), according to any number of online calendar converters. Algebraist 22:19, 27 January 2008 (UTC)

Thanks. Would that mean then that June 24 (Gregorian) = June 16th (Julian) in the 14th century? The Julian calendar was the one used in the 14th century, correct?--Doug ^talk 23:31, 27 January 2008 (UTC)

Yes and no. I'm assuming this is related to the Giovanni Boccaccio question at the Humanities desk. If you're interested in counting in exact 365- or 366-day periods between one event and another, then you'd say that exactly 695 such periods elapsed between 16 June 1313 and 24 June 2008. However, if Boccaccio was born on what was called "16 June" in 1313 (and we don't know that he was), then 16 June would still be his date of birth, not 24 June. That's because the Gregorian calendar was not applied retrospectively to 15 October 1582, the date it was introduced, and all Julian calendar dates prior to 15 October 1582 are still correct and valid. If Boccaccio had in fact been born on 24 June 1313 (the feast day of St John the Baptist) under the then-existing Julian calendar (and, again, there's no evidence for this), then we'd still say his date of birth was 24 June 1313, even though 695 full "years" wouldn't be finished until 2 July 2008. -- JackofOz (talk) 23:57, 27 January 2008 (UTC)

If you will also be dealing with dates at other times of year, note that the year itself may not be what you expect, as the year typically did not start on January 1 and the date when it did start varied from place to place. For example, the date we would call April 1, 1366, at the time in England would have been March 24, 1365, and the following day (the first of the new year) would have been March 25, 1366. Sometimes you will see the notation "March 24, 1365/66" used to remind you of this problem. --Anonymous, 00:00 UTC, January 28 (Gregorian), 2008.

January 28

Irreversible enzymes?

As a medical student rather well aware of chemistry, I have lately gotten a bit confused about the notion of enzymes catalyzing a reaction only in one direction. For example, hexokinase, an enzyme which catalyses the first step of glycolysis (turning glucose into glucose 6-phosphate), catalyzes the reaction in said direction. This has been referred to (by lecturers etc.) as an irreversible step, a step which is catalyzed in only one direction. The reaction can of course be reversed and is so in gluconeogenesis, where the reaction is catalyzed by another enzyme.

My questions regarding this are:

1. What mechanism allows an enzyme to catalyse a reaction in only one direction?
2. What effect will this have upon the balance of a reaction? While K_c should remain unchanged, adding e.g. hexokinase to a solution of glucose and glucose 6-phosphate should cause the balance to shift away from the equilibrium towards glucose 6-phosphate? OK, this is a bad example, since this step involves the hydrolysis of ATP, but suppose it didn't, or better up that my example was one which involved no other molecules but was otherwise the same, irreversible?

Thanks! ~Linus, 07:40, 28 January 2008 (UTC)

Strictly speaking all enzymes catalyze their specific reactions both ways; they do not shift the equilibrium. In the case of hexokinase (and some other enzymes), the reaction is called "irreversible" because the equilibrium clearly favors one side. Icek (talk) 14:22, 28 January 2008 (UTC)

Actually, the truth of the matter is that the equilibrium does not favor one side so clearly all the time. In the case of Glucose -> Glucose-6-phosphate, the hydrolysis of ATP provides a very favorable impetus for the forward reaction, which is why it is considered "irreversible". Nature couples ATP hydrolysis reactions with the reactions that need to go but don't go favorably enough.18.96.7.80 (talk) 16:17, 28 January 2008 (UTC)

Yes, ATP is the real secret escape from "catalysts don't change chemical equilibria." In a coupled reaction, you've added a new reactant and new products, and so the chemical equilibrium is changed as the chemical reaction is different. Someguy1221 (talk) 16:29, 28 January 2008 (UTC)

"Down's Syndrome" in animals

Does an analogous genetic disorder to Down's Syndrome exist in other species of animals? --Taraborn (talk) 02:48, 28 January 2008 (UTC)

Apparently not. However, this article says that by inserting human genes into lab rats, it may be possible to recreate Down's in other animals. [13]. bibliomaniac15 02:51, 28 January 2008 (UTC)

This website describes some very interesting mouse models of down syndrome, and suggestions on where to find papers on it. Someguy1221 (talk) 02:54, 28 January 2008 (UTC)

[14]. This states its in every population.its late.[15] [User:Mion|Mion]] (talk) 02:59, 28 January 2008 (UTC)

It's clearly referring to humans only, however. Someguy1221 (talk) 03:03, 28 January 2008 (UTC)

I think you're right Someguy,it's the extra 21st chromosome in humans that is named Down's Syndrome, now you can inject a artificial human something into a human/mouse to experiment or mimik effects, its still not the extra 21st chromosome in humans, i think similar errors happen in animals as well, but they have another name, so the answer is no the extra 21st chromosome in humans (down syndrome) is not present in animals. Mion (talk) 03:13, 28 January 2008 (UTC)

Some budgerigar breeders claim that the 'feather duster' mutation (which causes constant abnormal feather growth, deafness, blindness and mental retardation and is probably a result of too much inbreeding) is analogous to Down's Syndrome. I'm not sure if there has been any serious scientific research undertaken. --Kurt Shaped Box (talk) 07:35, 28 January 2008 (UTC)

Three Cases of Trisomy in the Mouse; A. B. Griffen; M. C. Bunker Proceedings of the National Academy of Sciences of the United States of America, Vol. 52, No. 5. (Nov. 15, 1964), pp. 1194-1198 states that trisomy which means a chromosom is present three times is also possible in mice.--Stone (talk) 07:52, 28 January 2008 (UTC)

I was under the belief that the white tiger in some of these pictures had Down's Syndrome but I believe this may be inaccurate and that it simply has a strange appearance due to huge amounts of inbreeding. Lanfear's Bane | t 12:15, 28 January 2008 (UTC)

Yeah, skull deformity !necessarily= Down's, even though it may look superficially similar. Interesting site though. It contradicts WP's own White tiger article with regards to the claimed 80% infant mortality rate, though... --Kurt Shaped Box (talk) 16:37, 28 January 2008 (UTC)

Is down's syndrome what most people refer to as "retarded"? 64.236.121.129 (talk) 17:09, 28 January 2008 (UTC)

Down's Syndrome is one potential cause of Mental retardation in humans. There are others. I don't know if it's considered polite to use the term 'retarded' (in a non-insulting manner) nowadays. --Kurt Shaped Box (talk) 17:19, 28 January 2008 (UTC)

Depth of ignition

At what depth and beyond will flammable material like clothing and paper inside a submarine hull ignite if the hull collapses? —Preceding unsigned comment added by 71.100.3.254 (talk) 08:00, 28 January 2008 (UTC)

I don't have any numbers for you. But, first: check the article on Self ignition. Next you want to measure how hot a gas will get when it's rapidly compressed, for that see Adiabatic compression. The final issue is that things will self ignite at a much lower temperature when the oxygen concentration is high. Now, I'm not sure that increasing the oxygen concentration by compression (not concentration really, but more like oxygen available near the item), is comparable to increasing it by having more oxygen, but it's got to have some effect. Ariel. (talk) 08:37, 28 January 2008 (UTC)

To the second part of your response, the answer is yes. In looking at the effective concentration of oxygen, the important term is the partial pressure of oxygen, not its relative fraction. Take ordinary room air (roughly 20% oxygen, 80% nitrogen) and compress it to a pressure of 5 atmospheres—that gives a partial pressure of oxygen of 5 atm * 20%: one atmosphere. Under those conditions, fires will burn essentially the same way they would under 100% oxygen at regular atmospheric pressure. (For similar reasons, deep-sea scuba divers use gas blends that contain reduced oxygen – heliox or trimix often contain 10% oxygen, for example – to reduce the partial pressure of oxygen that the divers breathe at extreme depths and reduce oxygen toxicity.) TenOfAllTrades(talk) 22:17, 28 January 2008 (UTC)

Musical brains

Has any research been done into the structure and function of the brains of composers (as compared to the brains of the rest of us)? I ask because it struck me the other day just how amazing it is to be able to produce new tunes (almost at will in the case of some "tin-pan alley" composers). DuncanHill (talk) 10:29, 28 January 2008 (UTC)

The brains of composers are much more succulent than those of ordinary humans. Weasly (talk) 11:16, 28 January 2008 (UTC)

On the topic perhaps this link would be useful to you. Lanfear's Bane | t 12:05, 28 January 2008 (UTC)

Or this one (or this ) (must get round to reading this book myself) AndrewWTaylor (talk) 14:28, 28 January 2008 (UTC)

Phage titration / Identify bacteria

I have reading material written by a non-native English speaker and it says that "bacteria [can be] characterised by phage titration" (this is to confirm the integrity of an E. coli K12 DH5alpha culture). What are they trying to say? I think phage titration would be where you determine the number of phage per ml of a solution. ----Seans Potato Business 10:55, 28 January 2008 (UTC)

Digital modulation transmission rates

I have a doubt about how can I manage the transmission rates on a system designed to allow multiple modulation schemes - for example, systems using the 802.16 standard. If the system uses BPSK I'll have a symbol rate equal to the data rate. If after a while I change the modulation, for example, to 16-QAM, the symbol rate will be 1/4 of the data rate, so, if the data rate remains unchanged, I'll not have a higher transmission rate, so, I wonder if those systems are operated by multiplying the data bit rate by the a constant dictated by the modulation in use (4 in 16-QAM, 6 in 64-QAM, etc.) in order to keep the symbol rate constant. Can you help me with that? Thanks in advance. 84.91.38.179 (talk) 10:58, 28 January 2008 (UTC)

I found something. It may answer your Question [16]--TreeSmiler (talk) 02:16, 29 January 2008 (UTC)

Classifying transformed bacteria (biohazard)

If I was handling, experimentally, a high concentration of a very immunogenic protein, would that pose a risk? I'm a uni student and as part of an assignment, I have to classify E. coli K12 bacteria that has been transformed with ppUL32 of the cytomegalovirus. The bacteria is class I, and the viral protein shouldn't be harmful in "normal" concentrations (the concentration at which it would accumulate in a CMV infection) but the protein is highly immunogenic (the most immunogenic of all CMV proteins). Thus, could the transformed bacteria be classed as class II? As a separate question, does the concentrated protein post an immunomodulatory threat? ----Seans Potato Business 12:27, 28 January 2008 (UTC)

Isn't the E. coli K12 used for educational purposes not the same "bad" E. coli found intestines. According to the escherichia coli article, E. coli K12 "have lost their ability to thrive in the intestine". -- MacAddct  1984 ^{(talk &#149; contribs)} 20:33, 28 January 2008 (UTC)

Yes but it's important to take into account the danger posed by the genetic construct with which it was transformed. All E. coli K12 are not equal - indeed, some will be considered very hazardous and warrant level 4 containment, depending on the way in which they were modified (obviously strains modified in this way aren't used for normal educational purposes). ----Seans Potato Business 21:44, 28 January 2008 (UTC)

What major would this fall under?

Lets say I want to build weapons, design new and different engines, cars and other vehicles. What college major would that fall under? 64.236.121.129 (talk) 17:08, 28 January 2008 (UTC)

Mechanical Engineering. Possibly aerospace engineering depending on the type of weapons and engines, but mechanical has that whole spectrum. 18.33.0.55 (talk) 17:26, 28 January 2008 (UTC)

British Rail Steam Locomotives

Some Tank engines used the suffix MT, what did the M stand for?90.198.148.196 (talk) 17:09, 28 January 2008 (UTC)

How was the suffix used? At LMS locomotive numbering and classification#LMS System it refers to MT meaning "mixed traffic"; that would be as part of a class designation rather than, for example, a wheel arrangement. --Anonymous, 23:40 UTC, January 28, 2008.

IMAX lamps -- as hot as the sun?

While waiting for an IMAX film to begin the other day, the trivia section in the beginning informed me that its lamps get as hot as the surface of the Sun. This claim is repeated on the web, e.g. here. Is this possible?

The Sun article says that the surface of the sun is over 5000 °C. At that temperature, isn't just about everything a gas? The article on the bulbs used in an IMAX theater, Xenon arc lamps, mentions that they use "fused quartz" electrodes. While I couldn't find anything on fused quartz, the Quartz article says that it has a melting point of about 1600 °C, well under the temperature on the surface of the sun.

Is their claim likely?

Thanks! — Sam

While you're quite correct that the solid components of the lamp would not survive at five-thousand-degree temperatures, the arc itself can get that hot. The arc is a hot plasma that only slowly conducts heat out to the electrodes and quartz lamp envelope. (This is why high-powered xenon arc lamps require water cooling—without it, the electrodes would heat to melting and the lamp would fail.) TenOfAllTrades(talk) 17:52, 28 January 2008 (UTC)

Thank you! — Sam —Preceding unsigned comment added by 63.138.152.238 (talk) 17:59, 28 January 2008 (UTC)

You might enjoy our article on Xenon arc lamps, the technology used in the IMAX projectors. And yes, the arc is very hot.

Atlant (talk) 23:46, 28 January 2008 (UTC)

How well would modern body armor stand up to musket fire?

Lets say, muskets used during the American Revolutionary War and rifled muskets used during the American Civil War. 64.236.121.129 (talk) 17:46, 28 January 2008 (UTC)

Body_armor#Performance_standards is relevant. There are many different levels of body armor. I would suspect that a typical musket of that era is comparable to say, a shotgun slug, in performance. Pretty much even the wimpy body armor should stop a large, slow-moving. not-pointed projectile. Speed and shape of the bullet make a large difference. Friday (talk) 17:52, 28 January 2008 (UTC)

Sounds about right. The soft non-jacketed lead will also aid energy dissipation. — Lomn 18:06, 28 January 2008 (UTC)

Do British men have higher pitched voices than American men?

If so, why? 64.236.121.129 (talk) 17:48, 28 January 2008 (UTC)

Apparently not. wikisource:The American Language/Chapter 29. "the American voice in general starts on a higher plane, is normally pitched higher than the British voice". Martinp23 19:04, 28 January 2008 (UTC)

I do think that British men are more likely to vary the pitch of their voices. DuncanHill (talk) 19:14, 28 January 2008 (UTC)

Compare Prince Charles and George Bush : ) Julia Rossi (talk) 02:59, 29 January 2008 (UTC)

Hardly what one might consider a representative statistical sample.  :) -- JackofOz (talk) 03:08, 29 January 2008 (UTC)

Species Identification

File:South African Insect.JPG

Who am I?

I was wondering if anyone could identify the species pictured in Image:South African Insect.JPG; the photo was taken in the Madikwe Game Reserve in South Africa which borders Botswana. —Preceding unsigned comment added by Guest9999 (talk • contribs)

It is a foaming grasshopper from the family Pyrgomorphidae. Genus Dictyophorus and probably D. spumans. Colourful South African grasshoppers tend to be poisonous. Take care. (online reference image) -- Lycaon (talk) 23:46, 28 January 2008 (UTC)

Thanks for the information. Guest9999 (talk) 01:31, 29 January 2008 (UTC)

That's a nice photo you took, Guest9999. -GTBacchus^(talk) 00:01, 29 January 2008 (UTC)

Thanks. Guest9999 (talk) 01:32, 29 January 2008 (UTC)

β-mercaptoethanol uses

Along with smelling horrendous, I recall using β-mercaptoethanol as an ingredient for a DNA stain. I think it was when we did DNA sequencing. The article does not mention anything about its use in stains. Anyone have an idea? -- MacAddct  1984 ^{(talk &#149; contribs)} 19:06, 28 January 2008 (UTC)

Alkaline drinking water

I saw this advertised on TV today: a machine that makes your drinking water more alkaline (to a pH of about 10) so that it supposedly neutralizes the harmful health effects of acidic soft drinks. Is there any scientific basis for this? Wouldn't the alkalinity actually make you sicker? --Anakata (talk) 01:01, 29 January 2008 (UTC)

I'd certainly have thought so. If it didn't give you acid burns to your throat on the way down, it would certainly have a good go at neutralising the acid in your stomach. Acidic soft drinks are certainly less acidic than your stomach acid, so if anything they would make your stomach less acidic. -mattbuck 01:23, 29 January 2008 (UTC)

Mild alkalinity isn't any worse for you than mild acidity is. Your stomach is already highly acidic, so a little acid or base either way isn't generally going to make any difference at all.

The harmful effects of the acidity in soft drinks are, I believe, the way they dissolve your teeth. So unless you took a quick drink of your allegedly-neutralizing tap water immediately after every soft drink you drank, I can't see this claim as having any validity. —Steve Summit (talk) 01:17, 29 January 2008 (UTC)

Have a good read of this before you buy anything. There is a heck of a lot of water-related quackery about. --Kurt Shaped Box (talk) 01:29, 29 January 2008 (UTC)

What you really want is this stuff. Someguy1221 (talk) 01:33, 29 January 2008 (UTC)

Heh. I remember seeing some new-age crackpot selling (expensive) little bottles of 'activated water concentrate' on one of those TV shopping channels a couple of years ago... --Kurt Shaped Box (talk) 01:45, 29 January 2008 (UTC)

Read about Phosphoric acid. It's pretty bad for you, and I'm not so sure that neutralizing it in the stomach will be all that effective. Ariel. (talk) 02:27, 29 January 2008 (UTC)

Global Warming/Greenhouse Gases

The Wikipedia article on global warming shows percent ranges for greenhouse gases: 36-70% water vapor, 9-26% CO2, 4-9% methane, and 3-7% ozone. It seems to me the range for water vapor is impossible. If water vapor was under 58% it would be impossible to have 100% of greenhouse gases represented. I understand there are minor greenhouse gases that may be included, but nowhere near enough to make the percents come out to 100%. I would appreciate an explanation as I am using this data in a speech on climate change. Roy Mc (talk) 02:06, 29 January 2008 (UTC)

Like everything to do with global warming there are 1 billion sources saying 1 billion different things. It was (almost) universally accepted for a long time that water vapour contributed 95% - 98%. You would need to see check the sources from the article to figure this out.--155.144.251.120 (talk) 02:47, 29 January 2008 (UTC)

Are these whales using tools?

See crows using "tools" here [17] and chimps here [18], I was wondering if humpback whales using bubbles to "net" herring [19], are also animals that are using tools? Julia Rossi (talk) 02:33, 29 January 2008 (UTC)

There's a species of shrimp which snaps its claws together to create a sound shock that stuns nearby shrimp. Is that a tool? The question here is, what do you define as a tool?18.96.7.80 (talk) 02:46, 29 January 2008 (UTC)

Clever little shrimp. I'm wondering what defines a tool and how much consciousness goes into making it for use. If a tool is a device used with conscious intent, technique's in there too... In the article about the apes scientists are excited because it's to do with the human evolution scale. What happens to that when you say more than chimps use tools? Julia Rossi (talk) 03:11, 29 January 2008 (UTC)

Does light have a finite distance it can cover?

My question is about the distance light can travel. Does it go on forever or does it "weaken" over distance eventually coming to a "stop" or "disappearing?" If I was in outter space and shone on of those million candle watt power flashlights toward a nearby star, will the light ever reach there? If not, what happens to it?