Wikipedia:Reference desk/Archives/Science/2006 September 24

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Landmines in films

Hello

In films, whenever someone steps on a landmine there is a 'click', and it doesn't explode until they step off the device. This seems unlikely to me, a more sensible plan would be to make the mine explode as soon as it is stepped on. All the info I've seen seems to agree with this. Is this just another Hollywood myth, or is there some basis for it? Maybe early landmines worked like this.

Thank you!

Bill --82.163.182.64 00:02, 24 September 2006 (UTC)

I've often had the same thought. StuRat 03:34, 24 September 2006 (UTC)

Anti-personnel mine gives the impression that there is no such delay on directy trigger land mines, and it does seem like something Hollywood would like to exploit. Not every movie does, mind you. I don't remember any scenes like that in Saving Private Ryan, although there may have been a one-second delay after triggering or something like that.  freshofftheufoΓΛĿЌ  05:28, 24 September 2006 (UTC)

You can read about this fallacy in S-mine#Usage. dpotter 05:43, 24 September 2006 (UTC)

Now that that is cleared up, a little anecdote. During army training a sergeant (or such) demonstrated to new recruits that a tank mine is harmless to people by stepping on one. To drive the point through, he started jumping, which turned out not to be such a bright idea. Who said evolution no longer works in humans? :) DirkvdM 08:05, 24 September 2006 (UTC)

We were told (in the NZ Army) that the click is bs, if you actually step on a mine you won't know till it blows. and we were also told an interesting point about antitank mines, the trip pressure is set high enough so people don't fire it, (eg. the barmine is 140 kg) but if you get a healthy infantryman (lets say 90-100 kg), rifle (3.5 kg), pyrotechnics (say 1 kg) water (upwards of 2 kg), pack with personal ammo, gear and section ammo (easily 30-40 kg)... pretty soon you get into the region where that mine is not so much an anti-tank mine as an anti-soldier mine. Xcomradex 08:57, 24 September 2006 (UTC)

Excellent, thanks for the help Bill 82.163.182.64

Yeah, thanks for the help Bill!  freshofftheufoΓΛĿЌ  05:54, 25 September 2006 (UTC)

OK, but isn't there some kind of mine or other incendiary device; it may have been called a "bouncing betty" or similar, which, when stepped on, triggered some kind of spring mechanism, so that when you stepped off, the bloody thing leapt up into the air a metre or so before detonating? I thought the idea was improved killing and wounding by getting a larger area for the blast to act over, or some such. I imagine you'd hear a click when you stepped on it. Mattopaedia 09:12, 28 September 2006 (UTC)

Bouncing betty is the correct slang term. The idea is that rather than simply blowing off your extremities, a detonation a metre high or so will blow your guts out, killing you and any surrounding personnel.

Atlant 16:52, 29 September 2006 (UTC)

Gulls vs. Magpies - update

Not really a question, but an anecdote. I threw some food out for the birds yesterday (pieces of *cooked* sausage, for anyone that cares), expecting the usual flock of gulls to fly down and feast. A magpie flew down first and started to eat, blissfully unaware of the large herring gull walking up behind it. The gull almost nonchalantly picked up the magpie by the neck, turned through 180 degrees and deposited it, unharmed on the ground, then walked towards the food. The magpie chattered in protest a few times, then backed off, standing around and folornly watching the gulls chow down. Wish I'd had my camera. --Kurt Shaped Box 01:59, 24 September 2006 (UTC)

LOL, that's rather rude behavior StuRat 03:32, 24 September 2006 (UTC)

So the answer is : unmentionable seabirds can be gentle if they want. The question is tho': dont you like sausages?--Light current 02:07, 24 September 2006 (UTC)

They'd fallen on the floor twixt grill and plate. No way was I going to eat them - you should see the state of my carpet. --Kurt Shaped Box 02:10, 24 September 2006 (UTC)

Many accept the 5 second rule as a matter of faith if not of microbiology. Some restaurants have the deep-fat fryer rule: if it came from the fryer and it hits the floor, another pass through the fryer will make it edible again.Edison 19:39, 24 September 2006 (UTC)

Many things on the floor are probably better for you than what comes out of a deep fryer. :-) StuRat 08:36, 25 September 2006 (UTC)

I saw two gulls fighting over a massive live crab in Travemünde dock. Truly amazing creatures. --Asterion^talk 01:12, 25 September 2006 (UTC)

Did they do that tug-o-war thing with their beaks? Check it: http://www.youtube.com/watch?v=CP9c70pYxy0&search=seagull --Kurt Shaped Box 09:02, 25 September 2006 (UTC)

Do Laughing Gulls fly with plastic bottles tied to their backs? Apparently they do and surprisingly well. An adult (we don’t know if male or female, an expert may be able to tell) member of the local flock at the beach I visit in Yucatán, México, has an empty plastic 600 ml. bottle (like those used for drinking water) tied to its back with a fishing cord. The bottle is few inches smaller than the gull’s body. As how and who performed the act of catching the bird and securing the bottle, there are several hypotheses amongst the beach goers that have seen the animal. One thing is evident: it is not any kind of scientific experiment. The gull seems to fly and feed normally. The flock doesn’t seem to mind the burden the bird has been subjected to carry, however the bird is wary of humans. Laughing gulls will come for the usual crumb but they fly away if one tries to approach them. The materials (the bottle and the fishing cord) are madly endurable. Sometimes the bottle has water inside, which I suppose should increase in weight and make the flight more difficult. It has been already a year since we saw it the first time. There should be a way to help this laughing gull. Does anybody know?189.148.68.187 (talk) 02:24, 17 October 2009 (UTC)

Energy Needed

How do I calculate for example how much energy I would need to send a 500 ton object hurtling throgh the air at 7.2 miles/s? It's coming out of a really big cannon.67.126.240.99 05:20, 24 September 2006 (UTC)

Read kinetic energy. You must figure out which of the varieties of ton and mile you have to use in converting to metric equivalents. The energy needed does not depend on the size of the cannon. --Lambiam^Talk 08:15, 24 September 2006 (UTC)

That's some big ol' cannon you got there boy. Even a supercannon can't fire a payload of more than about 10 tons. Look at the figures in our spacecraft propulsion article instead.--Shantavira 11:21, 24 September 2006 (UTC)

$E_{k}={\begin{matrix}{\frac {1}{2}}\end{matrix}}mv^{2}$

http://www.onlineconversion.com/energy.htm will do the unit conversions for you. Using British (long) tons and using an electric rail gun? I figure it would cost about $950,000 at my electric rate, if I plugged and chugged correctly. The web site will also convert to kilotons of explosive.Edison 20:06, 24 September 2006 (UTC)

Thanks For Your Help.

Google can also handle the unit conversions and the math for you, although you still need to know the formula to use. Like this. Chuck 19:24, 28 September 2006 (UTC)

Bath oils

Hello, I just wanted to know how to make bath oils. It's for my science project, and it has to have Aloe Vera in it. thankyou. From, sheen

Probably the easiest is to get some baby oil and some aloe vera gel from the pharmacy and mix the two. You can basically use almost any vegetable oil: olive oil, almond oil, grapeseed oil, canola oil, some of which are cheaper than others. If you have fresh aloe leaves, take off the skin to get the gel (pulp). The skins contain a powerful laxative, so don't lick your fingers. It is easier to mix in the oil (slowly, a few drops at a time!) into the gel than the other way around, othewise you may be stuck with gobs of aloe goo in the oil. Finally, you could mix in a bit of gentle liquid bath soap. Googling "make your own bath oil" may give you further ideas, like on how to scent the oil. --Lambiam^Talk 08:36, 24 September 2006 (UTC)

Urinate

Why is it that I cannot urinate when ever there are people around? What can I do to allow myself to be able to urinate easily even when people are around? Someone please help me...

The inhibition about going to the bathroom in front of people may be a natural protective mechanism, because when you're doing your business, you're vulnerable. Your protective instinct may be extra-strong. For men, using urinals might also introduce an extra element of 'performance anxiety' and a need to hurry and not just stand there like a tool, and that can make it harder to go. Try using the stall to pee and just staying in there until you go no matter how long it takes. Then you can gradually inure yourself to going with other people in the room, and once you've mastered that you can go back to the urinal. Anchoress 06:41, 24 September 2006 (UTC)

This is called paruresis. There are a few ideas mentioned in the article. I find that discreetly tickling the tip of my penis (I'm assuming you're a man! Anchoress, I thought you were a woman!) stimulates it to function in this circumstance. Also taking an end or corner stall makes it easier.--07:26, 24 September 2006 (UTC)

Anchoress's answer and advice didn't make me think she was a man. Women often know more about men than men know about men.---Sluzzelin 07:35, 24 September 2006 (UTC)

How would a woman know about this particular problem may I ask? To my knowledge women do not indulge in communal urination whilst standing or whilst being watched. Do they?--Light current 03:08, 25 September 2006 (UTC)

And of course the advice about staying there till it flows is clearly ludicrous. Men who 'hang out' in toilets for longer than about 30 sec are viewed by other customers as highly suspicious (as they could be doing a George Michael.--Light current 03:17, 25 September 2006 (UTC)

If you're a man, how would you know (per your own statement). If you're a woman - yeah, right. :) Just imagine a guy stating that men understand women better than they themselves do. I think by now it's time for men's lib. DirkvdM 08:11, 24 September 2006 (UTC)

You're right in pointing that out. I probably should have written "Women often know more about men than I know about men." (which implicitly answers your implied question) :) ---Sluzzelin 08:20, 24 September 2006 (UTC)

There is a muscle involved during urination, and this muscle acts like a valve which controls the flow. It opens when it is relaxed, if I recall correctly. This point becomes important in the design of washrooms. For example, urinals with partitions between them offer more privacy than those without, which influences the washroom occupancy rate. --HappyCamper 17:31, 24 September 2006 (UTC)

YOu mean there is a freer flow of customers when partitions are present? Also isnt this 'muscle' called the prostate gland?8-)--Light current 13:11, 25 September 2006 (UTC)

How about closing your eyes and imagining you are all alone?--Light current 03:14, 25 September 2006 (UTC)

It may not help you, but what I do when i have this problem is think back fondly on all the times I have urinated in complete solitude, i.e. at home or far off in the woods (ok that sounds bad, but whatever). Once I place myself there mentally, I quickly relax and can go. And don't worry about what someone else said about taking a long time. Guys aren't in there keeping track of who is doing what, they just want to go and leave. Everyone has anxious moments some times.

Yeah they want to go in peace without the thought of some pervert hanging out in there pee(p)ing--Light current 21:52, 25 September 2006 (UTC)

This question came up quite a while ago, and just as then, I had a possibly different theory about the whole thing. I remember being at a particularly busy pub. The line-up for the ladies' room was ridiculous while there was no line-up for the men's room (as is often the case). In this particular men's room they had one of those urinals that reached all the way to the floor, with no partitions, so there was definitely less, if any privacy. That normally wouldn't be that much of a problem for me, except for the fact that the atmosphere at the pub became rather "fun", for lack of a better term. All I mean to say is that the women got fed up with having to wait for the ladies' room, and just felt, "to hell with it, we'll just go into the men's room". So there I was, trying to do my thing when a bunch of rather attractive women came in giggling while I was basically there, how can I say this mildly, rather "exposed" to all these cute girls. In any case, at that point, urination became impossible. All you guys know what I'm talking about. But I should be clear, I'm not implying in any way that the questioner is gay. All I'm saying is that the strangest of things can cause sexual arousal, and in turn, when sexually aroused, urination becomes impossible for males. Loomis 00:57, 26 September 2006 (UTC)

Were you aroused, or just petrified?--Light current 01:21, 26 September 2006 (UTC)

air conditioners

isn't it true that they make things warmer instead of colder because they have fans in them?

First you must understand that "cold" is not an actual thing. It is the absence of "heat". Air conditioners work by moving heat around. Air conditioners work by taking the heat out of a room and putting it somewhere else, usually outside of the building it is in. Air conditioners do have fans in them, and all electric motors generate heat, but this heat is insignificant to the temperature of the room. See the article on air conditioners for a more indepth response.--Russoc4 15:16, 24 September 2006 (UTC)

...And you could say the same about refrigerators. Anything that consumes energy converts some of it into heat.--Shantavira 16:12, 24 September 2006 (UTC)

Neither is "heat" an actual thing. It's merely the effect of the motion of particles. Those particles are still moving when there's "cold", but at a slower rate. Wouldn't it be just as true to say that heat is the absence of cold, as it is to say that cold is the absence of heat? JackofOz 23:30, 24 September 2006 (UTC)

I only disagree with one point made above. The amount of heat is in no way insignificant to the temperature cooling. In Tokyo (and other large cities such as Hong Kong), the air conditioning of large buildings creates what is being called here as a concrete island, because the heat released by AC exhausts cannot circulate properly when exuded into the city air (which is crowded with other buildings). The heat produced is significant, raising the temperature of the entire downtown region of Tokyo a few degrees just a few years ago.  freshofftheufoΓΛĿЌ  00:40, 25 September 2006 (UTC)

There's a number of reasons for this microclimate effect, though, beyond air conditioning. Cities absorb the sun's heat into brick, concrete and (especially) asphalt. Windows often act as mirrors, rereflecting solar heat. Automobiles produce loads of heat; an internal combustion engine is just a well-controlled continuous gasoline explosion. People tend to be warmer than air temperature, and Tokyo has it's fair share of people. --ByeByeBaby 03:12, 25 September 2006 (UTC)

Yes, that is correct. Air conditioning is only considered one of a few causes of the concrete island effect. The prime minister of Japan, though, considers it major enough to have promoted a cool biz campain, which asked everybody to stop wearing ties and using their air conditioners so much.  freshofftheufoΓΛĿЌ  05:50, 25 September 2006 (UTC)

To back up what everyone is saying: air conditioners work fine even without fans (see refrigerator). Also, scientifically, heat is a quantity of thermal energy stored in a material, cold is what a weatherman calls Cleveland in February. The correlation my prof used was that you don't call suction as a force just like you don't call cold as an energy, they are both the lack of a more scientific quantity. --Jmeden2000 21:39, 25 September 2006 (UTC)

Emphysema

My girlfriend is 14 (yes cute, I know) and she has told me that she has genetic alpha 1-antitrypsin deficiency, and that doctors put her life expectancy at 25 tops from pulmonary emphysema. She accepts it as a part of herself, has lost hope, and that she is going to die in less than ten years, however I have faith in medicine and am watching of developments in the area. I've done some research at PubMed and the like, and there doesn't seem to be anything she can do but take the weekly injections of the alpha 1-antitrypsin harvested from blood donors. She does not want to suffer any more past her projected death date. Lung transplant wouldn't work because, aside from possible death, it isn't a cure, because the problem is the deficiency not the smoking. I have seen liver transplant as a "cure," but every time it was specifically mentioned of the other problem of the liver not secreting the substances properly leading to concentration, then liver failure. I don't see why a liver transplant wouldn't fix the problem, because it is the liver that is not producing the alpha 1-antitrypsin. If the procedure worked out well would she be fine? She can't die before adulthood—that's unacceptable. Don't tell me to consult a doctor for medical advice, and don't tell me to read the article. I'm not a newbie. Thank you much. — X [Mac Davis] (SUPERDESK|Help me improve)16:20, 24 September 2006 (UTC)

When I read these sorts of posts on the Wiki, as a human being I want to reach out and offer you some sincere food for thought. However, there are many times where talking in person with someone more informed would be much, much more appropriate. It sounds like you are in a complicated and unique situation, and it sounds like you need to sit down and have a serious and genuine conversation with someone you trust. At minimum, you should feel that this person is capable of giving you mature insight with respect to your thoughts and concerns. I suspect you might find that process to be more meaningful than what could be offered over the internet. --HappyCamper 17:17, 24 September 2006 (UTC)

Life is almost unbearable sometimes, and this sounds like one. What would one do if he had 10 years to live? Before the 1920s, diabetics had less life expectancy than that, but insulin came along in time for some. With genetic engineering and stem cell research there is some chance of an effective long term treatment coming along over that time span, provided it is a disease receiving some research dollars. Be aware that today you can be more informed than some specialists in a field if you keep up to date on legitimate internet publications. Keep the hope for a cure or effective treatment alive, and enjoy each day. Ten well spent years can be better than 30 wasted ones.Edison 20:13, 24 September 2006 (UTC)

I have no useful advice, and I'm sure you, Mac, would be able to collect information about her disease much more efficiently than I. I just want to remind you to realize, on the other hand, that she has to live and deal with her deficiency, and it may not be easy for her to talk about it in a completely rational way, so you shouldn't force her to. Advances in science will continue whether she (or probably, her parents, for they are likely the most influencial authority figures to her on the subject of her health) pays attention or not. If it's an issue of "now or never", then nobody can stop you from trying to help, but if the only thing you can contribute are maybes and in the futures, you might just end up causing more strain on your relationship. It sounds unfortunate that she "doesn't want to suffer [live] past her projected death date". Maybe it's your duty to inspire her.  freshofftheufoΓΛĿЌ  00:35, 25 September 2006 (UTC)

She does not want to be alive in the hospital for months or years just to prolong her life, which is perfectly understandable. — X [Mac Davis] (SUPERDESK|Help me improve)03:34, 25 September 2006 (UTC)

Yes, quite understandable. The way you portray her pessimism though makes it seem like she doesn't believe there's any chance she will live past 25 without having to deal with suffering, and thus she probably isn't thinking much about life past 25. If she's happy about life, she might not be so pessimistic about everything, and might start to believe that there is a way, or there should be a way, to overcome the disease, which would be a good first step. Anyways, good luck.  freshofftheufoΓΛĿЌ  05:47, 25 September 2006 (UTC)

Since you asked us not to, I won't suggest you get that important information from a person able to answer you the best, but if you aren't a newbie you should know that if an accurate and full answer fact-based answer is truly important to you, you won't get it here. If you aren't much older than your girlfriend, what you may need is the sympathy other editors have offered. From what little I know, I suspect your description includes at least one or two erroneous assumptions, but I don't whether the error(s) lie in your understanding of what she told you, her understanding of what she was told, or unusual features of her case (and of course, the erroneous assumptions may in fact be mine). Be skeptical and help her look for other perspectives. alteripse 00:43, 25 September 2006 (UTC)

Reading your description, the pessimism expressed by your girlfriend is out of proportion to my experiences with the disease. There are several reasons for this. First, the life expectancy (without knowing her degree of deficiency) is much closer to 40 years, especially if she does not smoke. Second, lung transplantation, while not a cure, is certainly a viable option that should not be taken off the table! Your instincts about liver transplantation are right on - if she develops liver failure and undergoes successful transplantation, she will not have to worry about the lung disease. Liver transplants are much more successful than lung transplants in the long term. As for options on the horizon, AAT deficiency is an attractive target for gene therapy. The small amount of enzyme needed to be replaced makes it likely that there will be therapy available to mitigate the lung disease within the next 15 years. The liver disease, obviously, will still have to be dealt with given the different mechanism of disease (though it is less predictable). All in all, it's a tough disease but one with many more options than seem to have been acknowledged! InvictaHOG 01:38, 25 September 2006 (UTC)

Thank you for everything—your comforting, advice, sincerity. The reason I said the two "Don'ts" are because I am already in the process of consulting several experts. About the liver transplantation, I am asking if a successful live transplant will cure it period, almost regardless of the situation. — X [Mac Davis] (SUPERDESK|Help me improve)

A successful living donor liver transplant will cure AAT deficiency. However, the liver transplant itself has its own attendant risks. The development of lung disease is slow and measurable. It is certainly possible to wait until the time when there are signs of lung damage before resorting to liver transplant - that will also give medicine a chance to find other treatments/cures. InvictaHOG 05:25, 25 September 2006 (UTC)

But don't complications arise mainly because the recipient is usually in terrible condition before the operation? — X [Mac Davis] (SUPERDESK|Help me improve)14:54, 25 September 2006 (UTC)

That can certainly be a factor. However, outside of the surgical and immediate post-operative risk, there's the immunosuppression with its attendant risks and long-term side effects as well as the risk for chronic rejection. It's a great solution for a vexing problem, but it's not something to be undertaken lightly (ie prior to change in pulmonary or liver function) InvictaHOG 00:27, 26 September 2006 (UTC)

Mac, I'm afraid I'll have to say what other people have been afraid to say. False hope is worse than no hope. If there isn't a treatment for your girlfriend's disease right now, don't expect one to be invented within 10 years. In my opinion, the best thing to do is to accept death and help her enjoy her last years of life.

Of course, I'm not wishing for your girlfriend to die within 10 years--I have no reason to do so. I'm hoping that a treatment of the disease will be invented in time to save her life. However, don't expect it to happen, because it likely won't. --Bowlhover 03:52, 26 September 2006 (UTC)

Diffusion & Concentraton

Why do molecules move from a region of high concentration to a region of low concentration?

Don't know if there is a more specific answer, but entropy seems to come into play. 1001001 16:46, 24 September 2006 (UTC)

Probability. Let's say the two regions are the same size and that there are 100 molecules in region A, only 10 in region B. Over time, Brownian motion moves half the molecules from one region to the other. So what happens? 50 move from A to B, while only 5 move from B to A. Clarityfiend 17:15, 24 September 2006 (UTC)

You can also talk about the concentration gradient in the system, which drives the system towards equilibrium. The "probability" explanation is related to results in statistical mechanics, whereas this one is more related to thermodynamics. Very interesting stuff might I add. Read up on chemical potential and the second law of thermodynamics too. --HappyCamper 17:20, 24 September 2006 (UTC)

There are lots of ways to think about your question....

The simple answer: it's a lot easier for a bunch of things to randomly spread out than to randomly come together. "Spreading out" = "moving from high concentration to low concentration". Another way to think of it is: Imagine a bunch of peanuts and a bunch of styrofoam together in a box that's continually shaking. Just because they're (pretty much) randomly moving around, the peanuts will tend to go where there aren't many peanuts, simply because they're going (they're moving from a place where they are to where they aren't).

If you want to ask another "why?", I think you start coming across things like "what is space?" and "what is a position?" and "why does time move towards the future instead of the other direction?" and "what is movement?". —AySz88\^-^ 01:29, 25 September 2006 (UTC)

Model 1: The molecules are so sparse that they don't hit each other (or are ghostly and therefore pass through each other) but do hit other barriers (to be described). Place a barrier through a box, separating it into two mirror identical regions. Start with a lot of molecules trapped one one side and very few on the other. Note that while the partition is there, more molecules hit the barrier in each second on the dense side than on the sparse side. If we remove the barrier suddenly, more molecules will pass from the dense side to the sparse side than vice versa (because the barrier doesn't stop them).

Model 2: As in model 1, but the molecules do bounde off each other. Any molecule approaching the space where the barrier was will either pass through that space or bounce off another molecule. If there are more molecules on one side or the other, we expect more molecules will approach the (unoccupied) barrier space from the dense side than from the sparse side (just as in Model 1). Since it would be freakishly unlikely that the few molecules would just happen to scatter the many molecules back where they came from, more molecules leave the dense region than enter the dense region. -- Fuzzyeric 03:31, 28 September 2006 (UTC)

Selectively-permeable membrane

A selectively-permeable membrane is made into a bag and is filled with a 5% sugar solution. The membrane is permeable to water but not to sugar. The bag is then placed into a glass containing a 10% sugar solution. What will happen to the size of the bag?

See osmosis. Hope you get an A. 1001001 16:48, 24 September 2006 (UTC)

Ask yourself what you think will happen to the concentration of the water, not just the sugar, and you will probably figure out the answer. Gary 17:43, 24 September 2006 (UTC)

Chemical composition of wine

What is it? From which elements/molecules/compounds does wine come from? --Fbv65edel / ☑t / ☛c || 17:48, 24 September 2006 (UTC)

Wine is not a chemical, it is a mixture of many ones, the flavours possibly from esters, the active compund would be ethanol. Philc _T^E_C^I 18:05, 24 September 2006 (UTC)

Aha. Thanks for your help. --Fbv65edel / ☑t / ☛c || 18:25, 24 September 2006 (UTC)

The most abundant chemical in wine is hydrogen oxide. --Lambiam^Talk 18:55, 24 September 2006 (UTC)

Hehe, fair enough, when I read that I thought you meant hydrogen per oxide, and I was thinking, "eh, that stuff pretty poisinous" shouldnt the hydrogen oxide page be a disambig between HO and H₂O? Philc _T^E_C^I 19:01, 24 September 2006 (UTC)

No I think you'ld become quite pale after drinking H2O2, and then you'ld dye! 8-)--Light current 03:36, 25 September 2006 (UTC)

I think you mean H₂O₂. There is also hydroxyl, which is the radical -OH. I don't think we need disambiguation. The term "hydrogen oxide" is not common. For increased jocular effect, use dihydrogen monoxide (DHMO). --Lambiam^Talk 19:31, 24 September 2006 (UTC)

Scientific American had an article on the chemistry of wine in the last decade or two. Very complex. You could probably search their online index, and then find the issue in a library or big city used book store. alteripse 00:24, 25 September 2006 (UTC)

Thin Layer Chromatography

I'm a little stumped here. We're going to use TLC in lab this week on a mixture of aspirin, acetaminophen, ibuprofen, and caffeine (all analgesics). I need to predict the R_f values for all 4 compounds. This means that whichever compound travels farther on the chromatography paper will have the higher R_f value. To do this I must determine the relative polarities of the molecules. I tried looking up water solubilites and I could either not find them or I found conflicting sources, so I have to resort to using the structure of each:

	Aspirin
	Acetaminophen
	Ibuprofen
	Caffeine

I think that aspirin and acetaminophen are more polar than caffeine and ibuprofen, but I'm not sure on the exact order of them, in decreasing polarity. Can anyone help me out? --Russoc4 18:19, 24 September 2006 (UTC)

Hmm...well, this is really an homework exercise, but some things you want to be concerned with, are the functional groups on each molecule, their relative size, and their relative solubility in the solvent you will be using. As a tip regarding aspirn and acetaminophen, there should be something about attachements to the benzene ring which would give the answer away...In particular, the -OH and -COOH parts. Come back if you have more questions :-) --HappyCamper 18:25, 24 September 2006 (UTC)

Well, on aspirin, there is a carboxylic acid and ester group on the same side of the benzene ring. On the acetaminophen, there is an amide and secondary amine on one side, with an OH on the other side. Does this mean that aspirin is more polar because they are on the same side? --Russoc4 18:32, 24 September 2006 (UTC)

Also, this website gives water solubilities in decreasing order as caffeine, ibuprofen, aspirin, then acetaminophen. The wikipedia article for caffeine says that it is slightly soluble while this website says its very soluble. Vague answers you give me here are not going to help much. Also, I don't consider a prelab like this to be as trivial as "homework". They expect us to research the topics and collaborate with others. --Russoc4 18:54, 24 September 2006 (UTC)

Let me tell you why I'm hesitating with this one. TLC depends on the solvent and on the solid phase. Are we using water here? It seems to be the case. TLC is a very flexible and powerful technique because you can play with both the solvent and the solid phase.

I find the ordering of solubilities given above a bit odd. Ibuprofen has a large organic group attached to the carboxylic acid. I would expect aspirin to be more soluble than ibuprofen, as it has more polarizable groups.

I keep on having this image of acetaminophen being a zwitterion in solution, but this seems unfavorable. If this were the case, in some sense it would be more "polar" than aspirin. I think the your initial reasoning you had isn't unreasonable. Think by analogy: which is more polar - cis-dicholoroethene, or trans-dichloroethene? I'd settle with aspirin for the same reason, but at the same time emphasize that from structural considerations alone, it should be expected that the bands would be close together. --HappyCamper 20:12, 24 September 2006 (UTC)

As someone said above, the solvent is pretty important (I'm assuming that you are using finely divided silica as the solid phase). If I were a lab teacher (still), I would use hexane as the solvent, as it would allow me to use shorter TLC strips, but I'm cheap that way. But you are more likely to be using a short organic solvent than water, so if you are going to look up solubilities and base your answer on those, then the water solubilities would probably tell you the affinity for the (polar) solid phase, whereas the the solubility in hexane will tell you how well that affinity will be "opposed".Tuckerekcut 20:25, 24 September 2006 (UTC)

It seems that the solvent is going to be 95% ethyl acetate and 5% acetic acid (which will be neither extremely polar nor extremely nonpolar). Also, we are going to synthesize aspirin, and will be given the other 3 to use as references in identifying the spots, but we still need to guesstimate the Rf values. I think I am going to list them as aspirin, acetaminophen, caffeine, then ibuprofen. --Russoc4 20:44, 24 September 2006 (UTC)

Note that the solvent above is not the stationary phase, which will be silica --Russoc4 21:15, 24 September 2006 (UTC)

something worth looking up for each will be the Partition coefficient, which will give you an idea of relative polarities. Xcomradex 22:09, 24 September 2006 (UTC)

I'm very familiar with this experiment, I assign it every year (though I only require my students to deduce the polarity information from their results!). Without giving the answer away, here are a few guidelines:

• The order of Rfs is independent of the eluent, and only dependent on the polarity of each molecule.
• There is no perfect number you can point to and say "That tells you the polarity. Remember, barium sulfate is much more polar than caffeine, but it's much less soluble! About the best things are partition coefficients (very hard to find) and for solvents you can use dielectric constant to some extent.
• The best way to judge polarity is to look at the balance of polar groups (O-H, N-H, C=O) vs nonpolar groups (C-H, C-C). If you have a lot of the former and few of the latter, your molecule will probably be pretty polar, and vice versa. This isn't perfect, because (as usual) things aren't as simple as that (this approach is flawed for at least one of the above molecules), but it would show a good effort if you try that.
• Acetaminophen does have a zwitterionic resonance form, and it is indeed minor, though it explains why an amide group is quite a polar group.

Some tips: Check that your spots are visible under UV before you run the plate (the ibuprofen doesn't show up well and often needs spotting several times), and don't pick up the TLC tank while the plate is running. Good luck! Walkerma 04:19, 25 September 2006 (UTC)

dc or ac?

At the same voltage, say 220 Volts, which is more dangerous to human beings. AC or DC?? Also, Which would be more fatal to humans, HVDC transmission lines or HVAC ones.nids(♂) 18:50, 24 September 2006 (UTC)

My phyics teacher always said its current that kills you not voltage anyway, but to answer the question, with AC the current is contantly passing through 0 so there would be less in total than with the same DC which is remains contstantly high. To answer question I assumed equal current. Philc _T^E_C^I 18:55, 24 September 2006 (UTC)

The current does reverse with ac, but you cannot therefore say that less cuurent is supplied. The rms current of the ac should be compared to the dc value to see which is greater. Im not saying that one isnt more dangerous than the other though.--Light current 00:07, 25 September 2006 (UTC)

I elaborate my question. Consider Human body to be a form of resistance. Take R dc= R ac for the moment, (even though there is a difference by the factor of 1.2). Now a person accidentaly touches a AC power line with 220V supply, and another one touches a DC power line with 220V suppy. Which one of them will be more fatally injured.nids(♂) 19:02, 24 September 2006 (UTC)

You can't be "more" or "less" fatally injured -- that's like being "a little bit pregnant"! :-) —Steve Summit (talk) 20:40, 24 September 2006 (UTC)

I thought there was a difference between the level of fatal injuries and Pregnancy.:)nids(♂) 20:52, 24 September 2006 (UTC)

I used to think that pregnancy is like a step function, but injury is like a continuous function, where we can have different levels.nids(♂) 20:54, 24 September 2006 (UTC)

You can't be "somewhat fatally injured". In terms of how life-threatening injuries can be, "fatal" is the top level. --Lambiam^Talk 21:06, 24 September 2006 (UTC)

It seems you dont know what fatal means, well it means causing death. And Lambiam has a point in saying your dead or youare arent, you cant be more or less dead. Hope that clears things up. Philc _T^E_C^I 22:17, 24 September 2006 (UTC)

Ahem! But to try to answer the question, one may consider 220 vac to be more dangerous becuase its peak value is 311V and is therefore more likely to drive higher peak currents through the body than 220v dc. But I think the distinction is pretty pointless as the current derived from much lower voltages (eg even 9v directly across the heart muscle or applied below the skin surface) can be lethal.--Light current 00:16, 25 September 2006 (UTC)

Based on what is written about this in our articles War of Currents (see in particular the section "Edison's propaganda") and Electric shock (see "Issues affecting lethality"), the verdict appears to be inconclusive: both are about equally dangerous. --Lambiam^Talk 19:06, 24 September 2006 (UTC)

Thanks for the link to Electric shock. But i think that there should be some conclusiveness now, atleast after a century after the debate started. Thanks anyways.nids(♂) 20:15, 24 September 2006 (UTC)

Thomas Edison's demonstrations were pretty conclusive that at voltages such as this AC is more deadly. Many animals, dogs up to elephants, were tested. This is not to say that 220 DC is even remotely safe. When you are talking HV such as 138kV, 500kv, etc, I expect that either would be quite deadly, that is, I would not expect anyone to survive even momentary contact, because of the arcing and burning and the enormous current in the fault through the victim having an explosive effect. A charred hunk of burned flesh would likely be all that was left even if the fault were interrupted as quickly as 6 cycles.Edison 20:22, 24 September 2006 (UTC)

Your namesake went overboard in his attempts to demonstrate that DC was safer than AC. Can we be sure the experimental set-up of his demonstrations was bias-free? --Lambiam^Talk 20:50, 24 September 2006 (UTC)

Yes, he was my Teacher's Teacher, and he did not lie as to the truth of electricity. Edison 04:21, 25 September 2006 (UTC)

One thing I read that seems plausible; if you grab a live wire with AC you can let go, whereas with DC the current will override neuromuscular control such that you can't let go--the muscles are clamped tight. Very bad. --GangofOne 21:03, 24 September 2006 (UTC)

I know people who grasped 240 V AC and could NOT let go. So we learned to touch it only with the BACK of the hand to avoid the involuntay contraction of the musculature. As always, do not try this at home.Edison 04:24, 25 September 2006 (UTC)

So considering these effects, can we say that DC is more dangerous (if not fatal).nids(♂) 21:29, 24 September 2006 (UTC)

No, you can't. It's an ill-formed question. The voltage and frequency both enter in to it. At some voltages, it's true, DC induces a neuromuscular grab reflex making it impossible to let go, so DC could be said to be more dangerous at those voltages. At some voltages and frequencies, the inductive coupling of AC will be more effective at inducing disruptive currents in the heart muscle and inducing cardiac arrest, but at other voltages and frequencies, it might be less effective (particularly due to skin effects). At really high currents and voltages, the burns will kill you whether your heart stops or not.

I think that ac also induces a neuromuscular grab reflex making it impossible to let go. Any induced currents in the heart due to current traversing some other path will be minisule and can be neglected. We dont have a transformer here just a big, slightly resistive, blob with some nice conducting channels (blood vessels). So if I sent some current from one of your feet to the other foot, most of it would go via the groin area. Nothing of any significance would be 'induced' in the heart. I therefore doubt that this form of electro'cution' would cause immediate death whatever the current. --Light current 00:24, 25 September 2006 (UTC)

The bottom line is that electricity is potentially dangerous (that's a little punny joke there, but it's true) and can kill you, period. The question of whether AC or DC is more dangerous probably wouldn't even come up if it weren't for those old, historical current wars. If you're asking out of curiosity, please settle for this. If you're asking because it's a homework question, ask your teacher which book's ill-founded pronouncement on the question your teacher considers "correct", and use that. (Or if you're courageous enough, tell your teacher that the question is ill-formed and that you refuse to answer it, and explain why.) —Steve Summit (talk) 21:56, 24 September 2006 (UTC)

This question was out of my curiosity. The frequency for the AC 220V is the normal 50Hz that is supplied(In the countries with 220V distribution). I dont trust my teachers and i have seen the consequences of correcting them. Some of my outstanding Physics teachers didnt even had their basic concepts clear. One of them went out of the way in explaining that AC is more dangerous in all circumstances and they also gave absurd reasons for that, but i know that they were wrong. Now, I dodnt even bother to correct them. I thank you all for the great response.nids(♂) 22:56, 24 September 2006 (UTC)

One more point I didn't mention is that in one respect, 50-60 Hz is said to be the most dangerous frequency you can use, i.e. one of the nasty AC effects is apparently magnified, for organisms of our size, at about that frequency range. (But I don't remember the details.) —Steve Summit (talk) 23:09, 24 September 2006 (UTC)

I havent heard that, and I cant think of a reason why it should be so. THe only thing thet could be magnified is the current, and since the body is basically resistive (not reactive) that aint gonna happen. Unless its to do with a heart preffered fibrillation frequency 8-)--Light current 00:29, 25 September 2006 (UTC)

Oh well maybe not:

Ventricular fibrillation, despite its appearance as a random waveform, has a clear dominant frequency with a narrow bandwidth and a peak in the power spectrum around 9 to 12 Hz, which changes with time, drugs and ischaemia.--Light current 00:34, 25 September 2006 (UTC)

Please believe this: AC or DC can be lethal, even at voltages below the 220 V described here. Thomas Edison and his henchmen proved that at various voltages such as 120V, 240V, and 400V, AC was more likely to cause sudden death than DC. But 200 V DC can cause grevious burns. A funny difference between DC arcs and AC arcs, based on observation, at voltages above 120 V: AC hums, while DC hisses.Edison 04:33, 25 September 2006 (UTC)

Hmmmmmmmmmmmmmmmmmmmmmmmm--Light current 15:25, 25 September 2006 (UTC)

It really all depends on how you apply this voltage, sweatiness of the hands, caridovascular health of the victim, time of exposure etc etc. There are no hard and fast rules except to say that any electric potential is more or less hazardous to life depending on the above--Light current 15:29, 25 September 2006 (UTC)

pyrex comosition

sorry if this appears to be a repeated question i did not put a heading last time. Does anyone know the chemical compostion of pyrex, like water is h20, as it did not have it on the article, just a chart. I need it for work.

Pyrex is a brand name for borosilicate glass (I wrote that before even reading the pyrex article). It is "about 70% silica, 10% boric oxide, 8% sodium oxide, 8% potassium oxide, and 1% calcium oxide" (that part i copied). Don't forget that this is an encyclopedia, just type in "pyrex" or "borosilicate glass" into the search pane to get more info.Tuckerekcut 20:13, 24 September 2006 (UTC)

Also, glass is amorphous, so it doesn't have repeating crystal structure. Nor is it a pure substance, It is more of a mixture, so there is no precise chemical formula. That would be like asking for the chemical formula of milk.Tuckerekcut 20:17, 24 September 2006 (UTC)

not all glasses are mixtures though, eg. fused quartz. Xcomradex 22:04, 24 September 2006 (UTC)

cell biology: cytolysis vs. plasmolysis

We got any cell biologists here? Can someone go over to the Lysis article and figure out what the right thing to do is with this note someone tacked on at the very end (down beneath the "See also" section):

Correction from mentioned above. In a hypertonic environment, plasmolysis occurs, which is nearly the complete opposite of cytolysis that occurs in hypotonic environments. Cytolysis does not occur under normal conditions in plant cells because plant cells have a strong cell wall that contains the osmotic pressure, or turgor pressure, that would otherwise cause cytolysis to occur.

Thanks. —Steve Summit (talk) 20:36, 24 September 2006 (UTC)

I'm not a cell biologist, but I gave it a try. --Allen 02:56, 25 September 2006 (UTC)

Managed Care

Does a physician "gatekeeper" work for or against the patient? 207.200.116.204 21:06, 24 September 2006 (UTC)

It depends on whether they have taken a Hypocritic Oath :)  --Lambiam^Talk 22:53, 24 September 2006 (UTC)

Is this homework? The intent of course is that they will work "for" the patient to obtain necessary medical care while preventing access to "unnecessary" care. Even when performed in good faith and honesty, there are at least two potential problems: (1) a patient may not always agree with what his/her doctor deems unnecessary care, and (2) if the financial incentives are strong enough to limit care, they will corrupt judgement and tempt the physician into having to choose between deciding on behalf of the patient or on behalf of the insurance company. The high tide of strict gatekeeping in the US was in the mid-1990s when some managed care companies directly subtracted the costs of consultation and tests from the amount that would be paid annually to the primary physician: i.e., any service the patient needed that he could not provide was in a sense directly charged to him. After some scandals and lawsuits this form of gatekeeping has been largely abandoned in the US, and few managed care companies penalize primary physicians for seeking specialist consultations or tests. The newest form of managed care interference with medical decisions is "performance pay", where doctors are judged by various objective measures of the care of their patients and are rewarded or penalized by how they rank (or patients may be penalized for seeking care from a doctor who ranks more expensively). Sounds OK until you think for a minute what it means if your doctor has to decide whether treating you is likely to help his statistics or hurt them, since every system like that will be "gamed" and it is not always easy to judge good medicine by countable parameters. alteripse 00:20, 25 September 2006 (UTC)

The issue of circumcision is notable here. Long story short, several different groups have supported it (many times for hidden motives), and now the physicians are the most prominant. Because they make several hundred to a thousand dollars per circumcision. The reality in the United States now is more "do you want your child's penis to fit in" rather than saftey. — X [Mac Davis] (SUPERDESK|Help me improve)03:38, 25 September 2006 (UTC)

Fit in where ? I do appreciate you clipping your comments short.  :-) StuRat 08:18, 25 September 2006 (UTC)

Don't embarrass yourself-- you have no idea what you are talking about and you are flat wrong. Do not listen to propaganda from the circ/anticirc warriors. alteripse 03:41, 25 September 2006 (UTC)

Just because you disagree with Mac, that's no reason to be so bris with him. Circumcision is, alas, a bleeding edge medical issue. :-) StuRat 08:23, 25 September 2006 (UTC)

Come on stu. This is not a matter of opinion, but fact. Mac is a kid but but you should be old enough to know better. The issue of circumcision has zero to do with "gatekeeping" and I am not simply disagreeing with an opinion. The custom for most routine American hospitals is that the nurses in the newborn nursery ask the parents if they want the child circumcised, and the doctor does the babies on the list (and before one of you suggests it, no she doesnt split the fee with the nurse for the referrals). The only circumcisions for which a doctor gets paid thousands of dollars are the few done by surgeons where the post-neonatal patient or family goes to the doctor and requests the circumcision. The suggestion that routine neonatal circumcision generates large enough fees that doctors solicit the procedure from families of newborns is invidious adolescent fantasy. alteripse 10:28, 25 September 2006 (UTC)

Well, you've really cut him down to size, haven't you ? :-) StuRat 12:27, 25 September 2006 (UTC)

Do you suppose that the doctors who perform the operation just get a flat fee ? Or do they get tips ? Gandalf61 12:52, 25 September 2006 (UTC)

Did you hear the one about the urologist who collected the removed tissues, and had them made into a wallet that expanded to a suitcase when rubbed? alteripse 17:19, 25 September 2006 (UTC)

No! And I dont want to. 8-)--Light current 22:51, 25 September 2006 (UTC)

I believe the 'offcuts' from infants can be rendered down to make stem cell material suitable for tissue regeneration. Is that correct and if so would the recipient be referred to as 'a chip off the young cock?'8-)

And if you cloned someone from those cells, would they turn out to be a huge dick ? :-) StuRat 09:51, 26 September 2006 (UTC)

You guys are hilarious. I have no idea what gatekeeping is (sounds a little out there if you ask me), but I think circumcision is overrated. Did I say thousands? I wouldn't expect that much, but it costs an extra few hundred. ;) Clitoridectomy anyone? — X [Mac Davis] (SUPERDESK|Help me improve)16:28, 26 September 2006 (UTC)

The idea of nurses routinely asking parents if they want their newborns circumcised is fascinating. In Oz, you pretty much can't get a cosmetic circumcision (neonatal or otherwise) as a public patient. Some surgeons and GPs perform them privately, but not so many. Most doctors and nurses here find neonatal circumcision cruel and unnecessary. Its probably more a reflection on the difference between the two health systems. What's it like in the UK under the NHS? Anyone? Mattopaedia 09:42, 28 September 2006 (UTC)

Thermodynamics

I am trying to help my son with his homework and I am lost. Use the laws of thermodynamics to defend the statement that 100 percent of the electrical energy that goes into lighting a lamp is converted to thermal energy. Please help. Thanks!!!

At the lightbulb a part of it is converted into light and the rest into heat (thermal energy). My guess is you simply have to say that when the light hits an object it is converted into heat since the energy cannot magically leave the system. - Dammit 21:24, 24 September 2006 (UTC)

Even light is a form of Thermal energy with wavelength less than 700nm. So all the electrical energy is actually converted to thermal energy.nids(♂) 21:26, 24 September 2006 (UTC)

Or perhaps you are after the first law of thermodynamics, particularly conservation of energy. Xcomradex 22:00, 24 September 2006 (UTC)

Use the first law of thermodynamics plus the fact that the internal energy of the lit lamp (once it is up to temperature) is constant. So the increase in the internal energy of the system is zero. Then you have: heat in = work out. Or, in this case: heat out = work in. In a formula: $\Delta Q=\Delta W\,$. The heat energy given off to the environment is therefore equal to the electrical energy input. --Lambiam^Talk 22:50, 24 September 2006 (UTC)

Wait! I can't see! Where did the light go?! -- Fuzzyeric 03:44, 28 September 2006 (UTC)

If you shine a bright light onto a solar cell, a tiny portion will be converted back to electricity, so it would no longer be 100% converted to heat. StuRat 08:12, 25 September 2006 (UTC)

copper

What is the purpose of a layer of copper or aluminum on the bottom of stainless steel cookware?

It helps in proper dissipation of heat, since copper is a much better conductor of heat than steel.nids(♂) 21:27, 24 September 2006 (UTC)

Thermal Conductivity - note the relative positions of copper, aluminum, and stainless steel on the Thermal Conductivity chart. 71.96.28.140 21:30, 24 September 2006 (UTC)

Ideally the entire piece would be made of copper/aluminum, but that would bring the price way up.  freshofftheufoΓΛĿЌ  00:15, 25 September 2006 (UTC)

Or better yet, gold, then you wouldn't have to worry about tarnish. You also wouldn't have to worry about cleaning them, as they would be stolen before you had a chance to clean them. :-) StuRat 08:08, 25 September 2006 (UTC)

Gold will not serve any purpose other than its ornamental use, Since copper is still a better thermal conductor than Gold.nids(♂) 09:31, 25 September 2006 (UTC)

Actually, per volume is a better thermal conductor than silver and copper, as gold has more mass (and this is how it's measured. The best solution would probably be a stainless steel clad gold pan.

Gold is quite a good thermal conductor, however, 6 times better than steel, 50% better than aluminum, and only 18.5% worse than copper. When the ability to resist tarnish is considered, this would make gold a better choice. However, the price obviously makes this choice impractical. Silver is an even better thermal conductor than copper. It's price and tendency to tarnish also makes it less appealing to most people, however. [1]StuRat 10:23, 25 September 2006 (UTC)

You should have said "...and you'll never have to worry about cleaning them out, because that guy stalking you every day after work will have them cleaned out in a jiffy".  freshofftheufoΓΛĿЌ  12:08, 25 September 2006 (UTC)

LOL, Dirk seems to have avoided this problem by refusing to work at all. StuRat 12:23, 25 September 2006 (UTC)

What, with the kind of kitchenware I have to work with? Do you call cleaning my heavily tarnished pots and pans 'no work'? DirkvdM 08:30, 27 September 2006 (UTC)

The Dutch government doesn't provide those who refuse to work with a set of solid gold cookware ? I'm shocked ! StuRat 10:48, 27 September 2006 (UTC)

The thief might still have a copper chasing him, though. DirkvdM 08:30, 27 September 2006 (UTC)

Why do I have so much trouble picking up women in bars?

I'm really into attractive older women (say 40-ish, blonde and MILFy) but I never seem to have much luck. I'm 19 and they never seem to take me seriously, even when I turn on the charm (I'm pretty good at 'pulling' women of my own or similar age). Any tips? --84.69.92.146 22:18, 24 September 2006 (UTC)

If you have trouble picking up women and pulling them, I suggest using a dolly. :-) StuRat 18:23, 25 September 2006 (UTC)

The sheep? Man, that's nasty. :) --84.64.127.191 23:03, 25 September 2006 (UTC)

That was a test. There are many possible interpretations, such as a mobile pallet, but you picked the nastiest possible meaning. I guess we know what's on your mind. :-) StuRat 00:03, 26 September 2006 (UTC)

Still, you'd have to be pretty sick in the head want to to fuck a pallet, wouldn't you? --Kurt Shaped Box 00:30, 26 September 2006 (UTC)

What, are you one of those traditionalists that insists that the knothole remain on the tree ? :-) StuRat 09:48, 26 September 2006 (UTC)

It's the lying down vs. standing up debate again, isn't it? --Kurt Shaped Box 10:55, 26 September 2006 (UTC)

You're asking about this on Wikipedia? No wonder why they don't take you seriously. :P I'm not sure if us Wikipedians should either. :-) --HappyCamper 22:54, 24 September 2006 (UTC)

We don't tend to shy away from questions here, so give him a chance. The obvious reason has to do with motives. Women in their 40s generally aren't searching for a sex-relationship (that does not mean they don't want to have sex). Women in their 30s and 40s, if single, straight, and within the range "average" personality types, often would seem to be more interested in things like marriage, commitment, and security (i.e. money). Since it's difficult to see any of these things in a 19 year old man, they do not treat you seriously. Men tend to seek entirely different things, a lot of them being related to boobs. It is probably an instinct left over from our animal days, when a strong and reliable male was required to protect the female and her babies, and the more well-established the male, the better. Even successful women -- i.e. those who have established a level of security and a stable career for themselves -- seem only to be interested in successful men. If you really can't get off on anybody under the age of 30, try hanging around divorce groups and places where women complain about their fat, balding husbands.  freshofftheufoΓΛĿЌ  00:12, 25 September 2006 (UTC)

Yeah, youre just too young, poor, inexperienced, unsophisticated etc to attract these women.--Light current 00:38, 25 September 2006 (UTC)

That's the thing - I'm young, good looking and I can ejaculate like ten times a day without getting tired. You'd think at least some of these MILFs need a guy who could give them a real good seeeing to, even if it's just causual. :) --84.64.127.191 23:03, 25 September 2006 (UTC)

It may be causual, but is it effectory? JackofOz 23:14, 25 September 2006 (UTC)

Jack, I don't think you suitly emphazi your answer. Anchoress 23:48, 25 September 2006 (UTC)

No its OK. I understand Jack's joke! (It was a joke wasnt it?) 8-)--Light current 23:53, 25 September 2006 (UTC)

User:84; it really doesn't matter how many times you can ejaculate (unless we're on a desert island and I'm dehydrated). Once is enough. And the fact that you think ejaculating 10 times = giving a woman 'a good seeing to' says a lot more about you than it says about the women you're asking about. Anchoress 23:48, 25 September 2006 (UTC)

Very simply, what charms 19 year old women is unlikely to charm 40 year old women, especially since they will almost certainly see through any element of deception. (Not accusing you of dishonesty, "charm" is always full of deception and disrepect.) (The 19 year olds see through it, too, but they might be flattered by it; 40 year olds will need a lot more to be impressed.) Peter Grey 02:21, 25 September 2006 (UTC)

The Fundamental Equation of Sex: 19 goes into 40 more times than 40 goes into 19. This should work in your favor. Edison 04:38, 25 September 2006 (UTC)

Actually, 19 goes in to 40 very rarely indeed!--Light current 23:53, 25 September 2006 (UTC)

Have you considered using the internet to find the kind of person you're looking for? There are undoubtedly women of that age interested in having relationships with much younger men, but tey probably make up a smaller number of them. With the internet, you can narrow down your search to just that fraction that might be interested in a relationship with a 19-year-old. --Robert Merkel 04:45, 25 September 2006 (UTC)

Pffffft. I'm almost 40, blonde, etc etc, but I would NEVER consider someone who'd refer to me as 'MILFy'. And believe me, at our age, we can tell when that's what you're thinking, even if you don't say it. Get a little bit of respect for your elders, stop even thinking of us in those objectifying terms, and maybe we'll go to bed with you. A tip: at our age, we've learnt that the most important thing in a sexual or romantic relationship is respect. And we can tell if we're not getting it. And anyone who'd call me a MILF doesn't qualify as respectful in my book. Anchoress 04:59, 25 September 2006 (UTC)

I thought that older women found it flattering to be referred to as 'MILFs'? --84.64.127.191 22:59, 25 September 2006 (UTC)

Mothers I'd Like to Fuck? MOTHERS I'D LIKE TO FUCK? Where'd you hear that, on Girls Gone Wild? Maybe a 60 year old woman, or her mother, an 85 year old, would be flattered. But a 40 year old? Lots of guys want to fuck us. That's not our problem. Neat, interesting, cool, classy guys who want to fuck us, that would be flattering. But those guys wouldn't express it that way. Which is the point. Anchoress 23:12, 25 September 2006 (UTC)

Let me tell you how to pick up 40 year old chicks! Now listen up.

• take a $100 bill and wave it in front of her.
• take out a cigarette lighter and burn the $100 bill.
• tell her "Wait. There's more."
• burn another 12 $100 bills in front of her.
• Tell here you want to take her for a ride in your brand new Porche.

Easy! 202.168.50.40 05:02, 25 September 2006 (UTC)

Again, Pfffffffft. I'm not a hooker, but I'd be more likely to go to bed with him if he gave me the $1300. Like I said, respect. And a dude who doesn't respect his own hard-earned cash isn't gonna get any poontang from me. Anchoress 05:04, 25 September 2006 (UTC)

contrary to popular belief, respect is not an important facet of a relationship! I saw it on CNN, 20/20, Nightline, and 60 mins. Jasbutal 05:54, 25 September 2006 (UTC)

I'm confused. You said you'd be likely to go to bed with him for $1300, but he isn't going to get any poontang. Don't you think that's a little unfair?  freshofftheufoΓΛĿЌ  05:41, 25 September 2006 (UTC)

I said I wasn't going to give it up to someone who'd burn $1300. Anchoress 06:45, 25 September 2006 (UTC)

Ah, OK. That makes more sense.  freshofftheufoΓΛĿЌ  12:01, 25 September 2006 (UTC)

Nevertheless entering into a relationship with someone who is willing to give you $1300 just like that is rather naiave isnt it? If hes willing to blow it on you, he's willing to blow it on anything! ie he's irresponsible and not worth knowing.--Light current 00:11, 26 September 2006 (UTC)

Another useful tip. Learn Japanese fluently and become a host in Kabuki-cho in Tokyo. You probably won't be able to get a job there until you're 21 though. You'd better like asian girls though.  freshofftheufoΓΛĿЌ  05:39, 25 September 2006 (UTC)

Because you regard it as a scientific problem rather than a humanities one perhaps?--Shantavira 11:50, 25 September 2006 (UTC)

WTF is poontang?--Light current 00:07, 26 September 2006 (UTC)

I think it's Vietnam war slang. Something to do with what the hookers (remember to only fuck the ones that cough) the soldiers had sex with would say, or what their fellow Vietnamese referred to them as... --Kurt Shaped Box 00:24, 26 September 2006 (UTC)

Why only the coughers?--Light current 01:31, 26 September 2006 (UTC)

Full Metal Jacket - "Half the whores in Vietnam are serving agents for the VC - the other half have TB. Be sure to only fuck the ones that cough." --Kurt Shaped Box 01:52, 26 September 2006 (UTC)

Titanic boobies? IDKT--Light current 02:13, 26 September 2006 (UTC)

I really can't believe some of these guys. Eh, I feel sorry for Anchoress. No wonder women like to say guys are idiots. — X [Mac Davis] (SUPERDESK|Help me improve)16:40, 26 September 2006 (UTC)

I think that's Anchoress' point. Take any man, regardless of age, intellect, etc & remove that part of his brain concerned with sex and pursuit thereof. What you get then in his head is something like a marble in a coffee mug. The advantage of being a bit older as a man is you get a better understanding of people in general, and in particular, women. Women (generally) come to value relationships long before men do, and no woman in her right mind would jump in the sack with you if she thought she was basically just there to satisfy your little fantasies. That's what masturbation is for. Women deserve better. They should want better. Women who go for guys who treat them like dirt need psychological help. If guys who objectify women like that never got laid then natural selection would eradicate these silly attitudes eventually. Mattopaedia 11:05, 28 September 2006 (UTC)

LOL OK, back off a bit here. I'm NOT saying ANY of the things you said about men; I have nothing but respect for men, I do NOT think women are better than men (not saying you said that), and I don't think they're just sex fiends with enough brain matter left over for breathing and remembering sports statistics. Women AND men deserve better than to be treated as objects, that I can wholeheartedly agree with. Women who think a man is no more than his job and his ride AND men who think 'Nice tatas; I'd do you' is a compliment ALL need an attitude re-adjustment. Anchoress 04:25, 29 September 2006 (UTC)

The challenge is for all of us, male and female, to step up and take full responsibility for who we are as human beings. After decades (centuries) of being infantilized and looked down on, women are now beginning to do this (I'm being a little bit culture-specific here, I know I don't necessarily speak for the whole world). Now the tables have turned. Every time we (men or women) accept that men are too immature, self-centred and sex-obsessed to remember birthdays, do chores or talk to a woman's face rather than her chest, we're not only insulting men, we're denying them the pleasure and privilege of taking full responsibility for themselves. Anchoress 04:42, 29 September 2006 (UTC)

Yeah, OK, maybe I was gilding the lily a bit. But I'm a man and I'm allowed to. I don't believe you think all men are idiots, that women are better or that men are all "just sex fiends with enough brain matter left over for breathing and remembering sports statistics". No - we're very complex! We also have jobs, enjoy finding new reasons to have beer and pizza, and we can multitask too! I'll prove it: find a man - if you're in Australia right now there's a good chance he'll be watching the footy (go Swans!). Ok, look - he's watching the TV, drinking beer AND thinking about sex! That's three things!

OK, sorry, I really enjoy a good piss-take. Seriously though, the real reason I fired up a bit was I was reading this and thinking about the fact that my daughters are going to have to deal with all this BS and I took it personally. So I absolutely agree with you. The infantilisation thing's a bit wierd though, but I get your gist. My perception of the evolution of female civil rights was that, originally, they were considered a man's goods & chattel - weapons, shelter, clothes, food, livestock, slaves and wives. Now (in most parts of the world) that we've pretty much crawled out from under that rock, I have fairly high expectations of men & how they treat women (and themselves), and I can't help being disappointed when I see such uncouth behaviour. Cheers! Mattopaedia 03:16, 30 September 2006 (UTC)

I hear you, interesting post. Re: infantalization; I realised after I posted that the definition linked to isn't what I'm familiar with v/v the definitition of the word. What I mean, is that the (Western) subjugation of women included imbuing them with qualities of children, at least from the Victorian era to 30 years ago (barring brief breaks for the World Wars). Women were considered less strong, intelligent, competent and responsible than men; these assumptions were like a gilded cage: they relieved us from such responsibilities as competing for good jobs, making sure the house insurance was renewed on time, and applying for mortgages; but they also precluded us from those same things. IMO infantalization is now being foisted on Western men; they are characterised as big babies who have to be told over and over what to do, act out in immature ways when not carefully supervised, and are preoccupied with all things related to the human excretory system. This hurts men the same way its sister prejudice hurt women.

Also, I wanted to point out that it's not true that women have moved beyond being chattel in most of the world; in fact, regrettably in most of the world women are still methodically and diabolically oppressed and discriminated against. Institutionalised sexual violence; human trafficking; lack of access to work, higher education and reproductive choice; gender-biased legal repercussions for sexual impropriety; and acceptance of such practices as kidnapping and raping the woman you want to marry and genital mutilation are still commonplace. Anchoress 00:19, 1 October 2006 (UTC)

Anchoress says, "I'd be more likely to go to bed with him if he gave me the $1300." Reminds me of a joke I heard long ago: A man meets a woman and asks her, "Would you have sex with me if I gave you $100,000?" She says yes. He then asks, "Would you have sex with me if I gave you $100?" She says, "Of course not! What do you think I am?" He responds, "We've already established that. Now we're just haggling about the price." — Michael J 14:21, 30 September 2006 (UTC)

Exactly. This is related to a question I dare not ask (even here) for fear of being accused of mysogeny etc. Actually I forget the exact question now, but it was to do with people selling themselves.--Light current 00:36, 1 October 2006 (UTC)

static and dynamic lung volumes

Can you define static lung volumes and dynamic lung volumes?

I don't know what this is, but maybe you could find something from a medical dictionary? Maybe this would be of help. --HappyCamper 22:56, 24 September 2006 (UTC)

Dynamic lung volume refers to a partial lung volume which can be inhaled or exhaled in a certain amount of time. An often used Dynamic volume is the FEV1, which is the amount of air expired in the first second of expiration. Static lung volumes refer to the volumes of air inhaled or exhaled without reference to time, such as the tidal volume.Tuckerekcut 23:07, 24 September 2006 (UTC)

I thought: static lung volumes don't change - so Total lung capacity, residual volume, functional residual capacity; dynamic lung volumes can change - so tidal volume, forced vital capacity, FEV₁. But a med student's respirarory physiology might be better than mine. Mattopaedia 11:14, 28 September 2006 (UTC)

plasma (4th type of matter)

why are substances on earth found in the state of plasma?

You didn't like any of the examples listed in our Plasma article? —Steve Summit (talk) 23:05, 24 September 2006 (UTC)

I'm not sure what you are asking. I guess the answer to your question is that at least one electron has been removed from the atoms making up plasma. You can respond to this answer by clicking the "edit" button on the right, then adding your response to the end of the conversation. Gary 20:30, 25 September 2006 (UTC)

A source for bimetal strip coils

I am looking for a company that sells the bimetal coils that are used in old thermostats. I am tinkering with something and need a bimetal coil to regulate temperature, but don't want to spend $20 on a thermostat just to scavenge a bimetal strip(the whole thing probably won't cost $20). Preferably copper-steel, but I'm not picky. --Crazy Wolf 23:02, 24 September 2006 (UTC)

Can you not make your own by spot welding a strip of copper to a strip of steel?--Light current 23:51, 24 September 2006 (UTC)

I'd prefer buying them so that they are all the same shape and reactivity. --Crazy Wolf 00:07, 25 September 2006 (UTC)

i would imagine is probably cheaper to rip apart the thermostat. what you want sounds specialised, which means people will make you pay through the nose for it in my experience. Xcomradex 01:44, 25 September 2006 (UTC)

I found this via a Froogle search. Chuck 19:41, 28 September 2006 (UTC)

Castrated ejaculation?

When a castrated adult (with testes removed) ejaculates, the liquid that comes out is clear and a lot more thin (not globby). What is it exactly? Something is definitely missing, since the testes are not present. What remains in post-orchidectomy ejaculate?--Sonjaaa 23:19, 24 September 2006 (UTC)

Semen sans sperm?

from page on semen:

The bulk of the semen is composed of seminal plasma, the fluid portion of semen. This fluid is contributed by the accessory male reproductive organs. Some 60% of the volume of ejaculate is produced by the seminal vesicles, and most of the remainder is generated by the prostate. A small amount of viscous mucus secreted by the bulbourethral glands contributes to the cohesive jelly-like texture of semen.

--Light current 23:52, 24 September 2006 (UTC)

I can't help but ask the question: What would cause a castrated male to ejaculate? Isn't the vast bulk of a male's sex hormones produced in the testes? Without them, I would have assumed that the ability to orgasm and ejaculate would be eliminated. I must be wrong somewhere. Loomis 00:35, 26 September 2006 (UTC)

I think you may be right. The page on eunuchs may (or may not) be helpful--Light current 01:24, 26 September 2006 (UTC)

Well, I would assume that even a castrated male could nevertheless be sexually arroused, hence bloodflow would increase, and an erection would follow. I could then imagine, with enough stimulation, an orgasm being achieved - since an orgasm is simply a rapid contraction of muscles. Once again, I'm not so sure about the actual ejaculation. But then again, why am I 'imagining' such a thing? Oh look! The game is on. Time to watch muscular men in tights rolling around in the grass. - R_Lee_E (talk, contribs) 02:35, 26 September 2006 (UTC)

Perhaps the original questioner could be of help. S/he seems to have some actual experience with the whole thing for some reason for which I won't ask. Perhaps it would be helpful to look into the effect of a vasectomy on the composition of ejaculate. That one would make a lot more sense to me. All the sex hormones are still flowing as they should, yet the semen obviously contains no sperm (as that's the whole point of the whole procedure). It's very easy for me to understand how a vasectomized male can orgasm and ejaculate, but I still can't see how it's possible for a castrated male to do so. Loomis 01:07, 27 September 2006 (UTC)

What you were implying is correct, Light Current. The eunuch article is remarkably unhelpful. In particular, there's a section entitled "Myths", which seems to state that it's a myth that a eunuch has no sex drive and can't ejaculate, but then contradicts itself by saying that according to medical science, the myth may actually be true. This article definitely needs some improvement, as it provides no definitive information whatsoever on this particular aspect of the subject. The article on castration is far more informative. And come to thing of it, when you think of neutered dogs (or other animals), I've never heard of any of them being able to ejaculate. I'm actually very curious (though I do respect privacy) as to how the questioner ever came accross evidence of "castrated ejaculation" as it would appear to be medically impossible. Loomis 01:17, 27 September 2006 (UTC)

Treatment of MCAD

How is MCAD treated? The article doesn't say. Also, is it impossible for people with MCAD or similar diseases to lose fat? Jack Daw 23:57, 24 September 2006 (UTC)

The treatment of MCAD deficiency consists primarily of avoiding prolonged fasting and stress-induced catabolic states in early childhood. In other words, IV glucose is used in the event of a vomiting illness. There has been some advocacy of supplemental carnitine on theoretical grounds, but this is not universally recommended and there have been no conclusive studies to support it. Risk of metabolic decompensation and acute liver or heart failure seems to decrease with age. alteripse 00:05, 25 September 2006 (UTC)