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November 11

Shipping a private vehicle from the US to China

I would be very grateful if someone could help me locate information regarding shipping a private vehicle from the US to China. I haven't been able to turn up anything regarding rates, regulations, even approximate transit times. 218.25.32.210 (talk) 02:02, 11 November 2009 (UTC)

I don't have specifics - but I know it costs a couple of thousand dollars to ship a small car from Australia to the US - and maybe fifteen hundred to ship to the US from UK. The distances are kinda comparable. The saving grace might be that the US imports a VAST amount of bulky stuff from China - and exports a much smaller amount of more compact stuff back again. It follows that there are shiploads of mostly empty containers going from the US to China. The law of supply and demand says that it should be pretty cheap to ship your car. I know it takes about a month to ship a car from Australia - China ought to be similar. Regulations...sheesh...who knows?! It's a minefield. China may have easier regs than the US - but coming back in the opposite direction (from UK/Australia INTO the US), I wouldn't consider doing it unless the car was an 'antique' that would be exempt from emissions control & safety regulations, etc. SteveBaker (talk) 02:45, 11 November 2009 (UTC)

And that's just shipping charges. I think Israel charges 100% tax on US-made cars. DRosenbach ^{(Talk | Contribs)} 04:01, 11 November 2009 (UTC)

How does this fact connect with the question? Or do they already have rights to tax shippings between arbitrary countries?--131.188.3.20 (talk) 00:49, 13 November 2009 (UTC)

Thanks for the estimates, Steve. Foreigners in China actually get one tax-free import each last I checked. As you can imagine, there are all sorts of shady businesses here constantly bombarding us with offers to "buy" that free entry so that they can import a {insert suitably ultraexpensive brand} car under your name. The going rate in my part of the country is $3000~$4000, (legality aside) not bad at all if you're only here for a year or two and wouldn't have taken advantage of that right to begin with. 218.25.32.210 (talk) 04:58, 11 November 2009 (UTC)

Just a note here; Wikipedia does not, in any way, condone any illegal activity. —Preceding unsigned comment added by 157.203.42.175 (talk) 10:46, 11 November 2009 (UTC)

You're indeed correct that bulk shipping from the US to China is usually significantly cheaper then the reverse, so going solely by distance is probably not a good way to work out the cost. The only potential issue is that if you want to ship a car, it's going to need a large container. As a large amount of the traffic going back is probably smaller containers this is likely to be where you get the best prices but I presume you'd also get a decent price on a car too. However I have no idea what this is, and doubt anyone here does either so your best bet may be to actually ask a few shipping companies how much it would be. Nil Einne (talk) 12:03, 13 November 2009 (UTC)

exercising in smog

What's better for your health: Living in a place with high air pollution (smog) and trying not to "move" much, or moderately exercising although that implies breathing in more polluted air more deeply? Which would more likely improve your life quality and life expectancy in the long run?

I'm interested both theoretically and pragmatically: What would you consider for such a comparison? Only the harm to the lung vs. "all" benefits of exercising, or what else? To what extent does the baseline matter--e.g., is walking a total of half a mile and some stairs enough to give up further exercise? And down to earth: What's the rule of thumb you'd use to decide?

I'm asking because my friend (lower 30s, without health or weight problems so far) lives in Cairo, a city with considerable smog, and without easy-enough access to less-polluted areas for exercising. What would be your advice? Any thoughts? --Thanks for answering (talk) 02:07, 11 November 2009 (UTC) PS: Yes, I know you're not giving medical advice, yada-yada. But it's not exactly a question for which to see a doctor. :)

It's really impossible to generalize - and we don't know the nature of the pollution, the density of it, the need for the person to have additional exercise, what time is spent outdoors, what time indoors, whether filtered airconditioning is available, the age of the person, how long is spend exercising...there are WAY too many variables.

However, I'd ask you this: What is the proportion of the day you'd spend exercising? If you exercised for (let's say) 1 hour per day - which is arguably more than is really needed for normal health - and if you breathed (let's say) twice as fast and just as deeply during that time - then the amount of additional exposure you're getting by exercising is only around 5% more than you'd get if you didn't exercise. That seems rather little compared to the benefits of regular exercise. If you did your exercise in someplace with more filtered air (indoors - perhaps someplace with an airconditioner) - then you could easily control the amount of pollutants being cycled through the lungs during periods of high respiration. SteveBaker (talk) 02:32, 11 November 2009 (UTC)

"if you breathed (let's say) twice as fast and just as deeply during that time"

— SteveBaker

During exertion, tidal volume increases before respiratory rate. During heavy exertion, minute volume can reach 60 litres per minute, compared to about six litres per minute at rest. Axl ¤ [Talk] 08:20, 11 November 2009 (UTC)

This study examined the effect of acidic fog (sulphuric acid). They found only mild, short-term irritation in the lungs. Axl ¤ [Talk] 08:38, 11 November 2009 (UTC)

There is only limited information about this matter. Here are a couple of interesting articles, although they don't directly answer your question. My opinion (original research): there are only a few adverse effects from exercising in the polluted environment. It's probably better to take exercise in this situation, than not to take exercise. Axl ¤ [Talk] 08:45, 11 November 2009 (UTC)

How did you find the articles, Axl? Any particular search tool? ... - Thanks to both of you for your hard facts and speculations! Very interesting! And not being an (active) AC user, I didn't even know that they can have filters. :) Although then we probably get into the additional problem if the ACs are well-maintained or if they may spread additional unhealthy stuff like bacteria...

Steve Baker, type and density of pollution in Cairo don't seem to be well-studied (anyone needs a research topic? :))... but 2004 World Bank data found that Cairo had the highest amount of particular matter per m³ worldwide, and other stats weren't much better. It scored 10th for sulfur dioxides 1995-2001 (though I doubt that's still up-to-date information), and no information was published on nitrogen dioxides, but that would likely be pretty elevated as well. No idea if pollution is relatively evenly spread throughout the city, but Wikipedia says that Cairo's pollution is in part caused by cars, so presumably it is. ... Hmhm, you learn something new every day. :) So if you should have further facts or thoughts, keep them coming. --Thanks for answering (talk) 11:22, 11 November 2009 (UTC)

PS: Just in case someone else reads this and jumps to conclusions: Yes, the articles only found throat irritations, but that was because they were only looking for those. Smog has (for right or wrong) been compared to smoking cigarettes, and if you compare throat irritations of smokers and non-smokers, you'd find the same: only throat irritations. If you look at more severe long-term effects, however, you'll find more... Smog#Health_effects gives a little intro, but I'm not sure it covers all research there is about long-term effects... --Thanks for answering (talk) 14:02, 11 November 2009 (UTC)

According to the 2006 research Smog and Smug there is negative correlation between smog and smugness levels. I afraid that your friend have no other choice but to continue practice under heavy smog conditions, it's much safer than becoming smug.--Gilisa (talk) 16:38, 11 November 2009 (UTC)

"How did you find the articles, Axl?" I use PubMed. Axl ¤ [Talk] 18:35, 11 November 2009 (UTC)

Thanks! And no, Gilisa, I'll rather have friends who smugly protect the environment than some cool, but irresponsible people. The only problem is that in the US, people somehow believe that buying a huge hybrid car and then using it a lot somehow is environmentally responsible. Fortunately people abroad are a bit smarter about the environment or simply too poor to cause as many environmental problems as does the US... else the planet wouldn't be in noteworthy shape anymore anyways... --Thanks for answering (talk) 12:30, 13 November 2009 (UTC)

Electromagnetic Fields

A cat carrying a house mouse. Cuddlyable3 (talk) 17:27, 11 November 2009 (UTC)

I have a mouse problem and have considered buying a 2-in-1 mouse repeller - that uses an electromagnetic signal and an ultrasonic one (I've heard that they may not work; but with a money back guarantee I figure I've got nothing to lose). My flatmate is paranoid of such devices (despite living around mobile phones etc.) - does anyone have a link to a reputable website or verifiable Wikipedia page with some information supporting the safety of such devices? Ideally not a manufacturer's website, if possible. Thanks

I know this does not answer your question, but why not use a good old-fashioned mousetrap? They have never let me down, and you can get humane ones very easily, at least in the UK (which are unfortunately not included in the article).--Shantavira|^{feed me} 09:44, 11 November 2009 (UTC)

Thanks for the suggestion; one of the reasons I'm trying to use these deterrents (and avoiding traps and poison) is that I'm not convinced I can kill them faster than they can reproduce. I don't like the idea of clearing out loads of mouse corpses either, though I don't think that would be a problem as the damn things ignore the traps I have put down. —Preceding unsigned comment added by 157.203.42.175 (talk) 09:56, 11 November 2009 (UTC)

Well, the Wikipedia page is Electronic pest control, but that doesn't go into the safety. Electromagnetic radiation and health appears to be thoroughly referenced and might be of some use. AlmostReadytoFly (talk) 10:20, 11 November 2009 (UTC)

Thanks, this was particularly useful, especially the WHO references on the Electromagnetic radiation and health page. —Preceding unsigned comment added by 157.203.42.175 (talk) 10:44, 11 November 2009 (UTC)

I've tried 3 methods of mouse control, with varying success:

1) Traditional "break their necks" mouse traps. I never caught a single mouse with those.

2) Poison. This killed some mice, which I later smelled decomposing somewhere (one in the ceiling), and just blinded others, which then stumbled around my house until I did them in personally. Very messy and very cruel. The poison also stinks, and the decomposing mice gave off the chemical smell as well as the usual dead mouse smell.

3) Glue boards (with some grain as bait in the center). This trapped all the mice. Note that they are exceedingly cruel in that one mouse ripped off half of his face trying to escape. You also have to finish them off yourself, which I do by drowning (they drown in about 12 seconds). However, they solved the mouse problem quickly. Glue boards also catch insects and spiders, which is a nice side benefit, but does mean you need to add fresh boards every once in a while, as those coated with dead insects no longer can catch a mouse.

Also note that you need to figure out how mice are getting in and block that route. In my case we have an enclosed back porch which they apparently can enter, and from there they accessed the house through a door left open for ventilation. I now keep that door closed all the times. StuRat (talk) 14:20, 11 November 2009 (UTC)

Victor and RatZapper make electronic computerized mousetraps that are unbeatable. They operate on a few AA or C batteries. The Victor model sells for circa $17 at Amazon or in hardware stores. They have a microcomputer which uses the resistance between floor grids in an enclosed chamber to detect the presence of a rodent, then they apply a lethal jolt of electricity. The RatZapper allows a remote indicator to tell you when it has got one. The Victor has a blinking LED on top when it has got one. You dump out the carcass and push the reset button, then kill the next one. They do not steal the bait, nor do they spring the trap and get away as is common in spring traps. They do not get stuck and suffer like in glue traps. There is no fantasy of catching them in a live trap and releasing them outside (in which case they may be back inside before you are). Edison (talk) 15:27, 11 November 2009 (UTC)

We have some mouse traps we bought in the UK - they are slightly angled square cross-section tubes - sealed at one end with some bait (peanut butter works well) and with a trap-door on the other end. As the mouse walks into the trap, the tube kinda tips over (it's hard to explain in words) and the trapdoor is sprung. The mouse is perfectly OK inside and even has to peanut butter to enjoy. You take the tube to someplace a few miles from your house, unlock the trap door and up-end it and the mouse scurries away, none-the-worse for the experience. The trap can then be re-baited and re-used as many times as you need. So long as there aren't long-distance "homing mice" in your area you'll do fine! We caught several mice that way...until we moved out into the countryside where the rattlesnakes take care of the mice and all you have to worry about is not stepping on the snakes! SteveBaker (talk) 17:02, 11 November 2009 (UTC)

And for every mouse you release 5 miles from your house, someone will catch a mouse and release it by your house. This probably improves the genetics of the mice by reducing inbreeding, but it in no way reduces the number of mice entering homes. Edison (talk) 20:17, 11 November 2009 (UTC)

I would hope people don't release them near other people's houses... You go 5 miles away to the middle of a field or wood or, as a last resort, a park. --Tango (talk) 21:20, 11 November 2009 (UTC)

Or the exercise area of the local cat shelter. Googlemeister (talk) 21:28, 11 November 2009 (UTC)

Living in a messy student house a few years ago, I tried the live mouse trap described by SteveBaker, with mixed results - two mice went straight in, but there were one or two more which never did. An ultrasonic deterrent had no effect at all; I saw one mouse about a foot away from it. Eventually, just cleaning everything thoroughly and ensuring that all food was sealed away seemed to persuade them to leave. Warofdreams talk 02:26, 12 November 2009 (UTC)

Can you catch them faster than they reproduce? It depends, I imagine, but I once had a major mouse problem that got solved in literally two nights with some peanut butter and old-fashioned spring traps. They were, no joke, pretty much jumping onto the traps as far as I refilled them. (I had originally planned to not re-use the traps—just to dump them with the mice into the trash—but it became clear that there were way too many mice to do that without buying more traps.) I think over the course of two nights about a dozen mice wandered onto the traps we put out (sometimes while we were still in the room!!!). We never had any more mice trouble after that. We attribute it to the mice being not too bright and liking peanut butter a whole lot, and I know other people have had mixed results with such traps. But in our case, we were definitely able to get a handle on the mouse problem with traps alone. Horrifically, the mice we caught got smaller and smaller as things went on. "Mom, Dad, where are you? OH! Peanut butter!" --Mr.98 (talk) 21:57, 11 November 2009 (UTC)

• Mice don't like the smell of peppermint oil. Don't know why, they just don't. Apparently fabric softener sheets smell nasty to them too. Also, fine steel wool to block up the holes they use is a good deterrent. For a humane trap, rig up a tipping tube trap, like this. Fences&Windows 03:21, 12 November 2009 (UTC)

This type of devices does not work for roaches, despite what promoters claim. I'd be very hesitant to buy into their use against mice. Always research dissenting opinions before buying! 98.14.223.150 (talk) 17:43, 12 November 2009 (UTC)

Honey sugar

Think of a completely isolated country that has plenty of honey and very little if any sugar cane. Can they use their honey, of any type/flower source, to make something akin to granulated sugar, perhaps by leaving it in the sun spread flat for a few days? Could you use whatever they get through that to make toffee and that lot, or to put in a mix to make solid chocolate, and what might the difference in taste be? Lady BlahDeBlah (talk) 12:55, 11 November 2009 (UTC)

According to Honey, honey derives its sweetness from glucose and fructose monosaccharide. Since table sugar is sucrose; a disaccharide, (composed of fructose and glucose) it is theoretically possible to produce table sugar from honey, probably through polymerisation, ultimately likely to be through an industrial process. It's unlikely that honey would have a 50:50 split of glucose:fructose and therefore there would likely be waste of one of the monomers. Polymerisation generally requires the removal of water through enzymatic interation with the monomers, but I doubt this would occur were honey to be left out in the sun. With the prevelence of sugar cane and sugar beet derived sugars, I have doubts about whether this would even be an economically viable process. —Preceding unsigned comment added by 157.203.42.175 (talk) 13:08, 11 November 2009 (UTC)

Okay, so actual chemically-identical proper granulated sugar is impossible. That's fine. This country (which is a setting I am building upon) is renaissance-medieval with no industrial revolution in sight nor any external trade. Basically what I'm asking is can honey or dried/solid honey (or whatever-happens-to-sun-dried-honey) be used like cane sugar to make toffee, to put in tea, to make icing with, to sweeten eating chocolate with, etc, and how would it impact the taste? Lady BlahDeBlah (talk) 13:16, 11 November 2009 (UTC)

If you simply dried it you would just have dehydrated honey, and it would still taste like honey when you rehydrated it. So it would affect the taste of whatever you added it to. For many things, that would be OK, but some foods with a rather subtle taste might be overwhelmed by the taste of honey. It is certainly possible to extract glucose and fructose from honey, and these would be much more like table sugar, in that they would add sweetness with hardly any other flavor. StuRat (talk) 14:04, 11 November 2009 (UTC)

Would extracting the -oses be possible in the society's technology level I have described, though? Lady BlahDeBlah (talk) 14:19, 11 November 2009 (UTC)

Probably not. However, it wouldn't be beyond the realms of reasonability to suggest that dehydrated honey would make a substitute for what you've suggested. Honey would likely crystallise before supporting the growth of micro organisms (due to a low water activity) and could be expected to make reasonably good baked goods, perhaps with slightly different properties (cookies might be a lot more gooey, for instance). Don't forget that if this is a fictional universe, your characters would (presumably) have no appreciation of the qualities of table sugar and therefore be unaccustomed to anything else. Overpoweringly honey-tasting baked goods would be the norm if that were the only sweetener. —Preceding unsigned comment added by 157.203.42.175 (talk) 14:21, 11 November 2009 (UTC)

The transition from refined sugar from sugar cane to high fructose corn syrup in much of the sweetened food in the United States has shown that the population at large either adapts or does not notice some changes to the sweetening agent. Nimur (talk) 15:44, 11 November 2009 (UTC)

In a hypothetical world, you'd imagine that people would adjust their entire cuisine to the idea that sweet things have that honey flavor - so perhaps they'd never think to inject sweetness into subtly flavored foods - just as we don't put chili peppers into subtly flavored dishes. They would not even be aware that it was an issue. SteveBaker (talk) 16:53, 11 November 2009 (UTC)

As far as I know, refined sugar is a relative newcomer in some cuisines. For millennia, people around the Mediterranean have used honey, as well as dates, grapes, carob, figs and such (and Lead(II) acetate in ancient Rome) to sweeten their respective cuisine. Sugarcane was only introduced in the Mediterranean by Arabs after the advent of Islam, see Sugarcane. For example, the Seven Species of staple foods of the Land of Israel include grapes, figs, pomegranates, and dates, but not sugarcane; milk and honey are also mentioned explicitly. --Dr Dima (talk) 19:14, 11 November 2009 (UTC)

It's sort of ironic that the question refers to a "hypothetical" medieval country, but really applies quite genuinely to actual medieval Europe, where honey was relatively common but granular sugar was very rare and expensive. The main differences are that honey has a distinctive taste with a strong element of bitterness, and honey has different cooking properties -- it gives baked goods a stickier texture, and it isn't usable to make hard candy. Looie496 (talk) 19:29, 12 November 2009 (UTC)

I don't think that even cane sugar back then was refined in the same manner as our standard white sugar today and would most likely have been closer to brown sugar then white. Googlemeister (talk) 20:22, 12 November 2009 (UTC)

Speed of gravitons in a black hole?

What is the speed of the hypothetical particle which carries gravitational force, the graviton? If the graviton is limited by the speed of light, how can a black hole exist? The gravitons would need to move faster then light to escape the black hole, and if they didn't there would be no black hole in the first place? Are they superluminal particles? Could they be used to violate causality? —Preceding unsigned comment added by 80.2.204.230 (talk) 13:03, 11 November 2009 (UTC)

I'm not sure they "would need to move faster than light to escape the black hole"—presumably the graviton itself would not be affected by gravitational force, per se, but be the carrier of gravitational force. But perhaps someone else with a deeper knowledge can explain further. --Mr.98 (talk) 13:56, 11 November 2009 (UTC)

Pretty much any theory of gravitons would require that they travel at the speed of light and be influenced by the topology of space-time. In other words, they would pretty much have to be affected by gravity in addition to being the cause of gravitational force. Making that self-consistent with our large scale understanding of the universe is one of the reasons that a quantum theory of gravity has remained elusive. Dragons flight (talk) 16:11, 11 November 2009 (UTC)

Building off the above, the speed of gravity is well understood to be the speed of light. Regardless of the existence or properties of the graviton, it's empirically clear that (1) black holes exist despite the speed limit of gravity (or, if you prefer, the propagation of gravity is not restricted by a gravity field) and (2) gravity is subject to the same cosmic speed limit as everything else. Causality remains quite safe. Note also that causality may aggressively defend itself if you start getting too close to violating it. — Lomn 16:00, 11 November 2009 (UTC)

There was a similar question asked very recently. As I said there, the gravitational field of a black hole doesn't come from inside; it's actually left over from before the black hole formed. The answer to "how is this explained with virtual gravitons?" is that the virtual particle approach to forces isn't always useful and this is probably one of the times when it's not useful. -- BenRG (talk) 01:34, 12 November 2009 (UTC)

The structure of Einstein's general theory of relativity requires that everything is affected by gravity. (Specifically, the presence and strength of a gravitational field in a particular location depends on how you choose coordinates, so it is arbitrary. It therefore makes no sense to say 'not affected by gravity,' since how such a particle would move would depend on which coordinates were used by the physicist to describe spacetime.) 70.26.152.160 (talk) 04:39, 12 November 2009 (UTC)

The fossil gravity explains the black holes gravitational effect outside the event horizon. But is there still gravity at all inside the event horizon, bearing in mind the >c escape velocity within?80.0.100.27 (talk) 10:30, 12 November 2009 (UTC)

There is curved spacetime, i.e. gravity, inside a black hole. There's no sudden change in the field when you cross the event horizon; you feel what you felt before, namely, increasingly strong tidal forces. The field inside comes from the collapsing matter after it crosses the event horizon. The idea of "escape velocity" probably isn't useful here either. Escape velocity is the minimum outward velocity a free-falling object must be given such that it will never fall back down. A powered object (like a rocket ship) can escape at a much slower speed if it wants to. You can't explain the one-way nature of the event horizon by saying that the escape velocity is c there. -- BenRG (talk) 18:59, 12 November 2009 (UTC)

heptane, 3-methylene-

Is there any chemical information available about heptane, 3-methylene- ?? I am looking for a CAS# and/or a MSDS if possible. Timetraveler 013 (talk) 13:04, 11 November 2009 (UTC)

Is this the same compound than 2-Ethyl-1-hexene (CAS 1632-16-29 ?--Stone (talk) 13:57, 11 November 2009 (UTC)

Iron ore question

Hello. I left a post here a bit ago (and linked to it at Talk:Iron) yet it hasn't received any response, so I thought someone here may have some information that could help answer the question. Thanks. The Seeker 4 Talk 16:36, 11 November 2009 (UTC)

Thats a good question, but I've no good answer. All I can tell is that iron made tools from 2000BC were found in what was once Mesopotamia and that iron carburizing was known process in the Middle East at about 1200BC (this could be a byproduct discovery of iron production process). I guess that they just identified minerals rich with iron ore by sight. But I will look for additional information on the web to answer this.--Gilisa (talk) 17:06, 11 November 2009 (UTC)

• I found this book[1]. Seems like it should include an answer.--Gilisa (talk) 17:14, 11 November 2009 (UTC)

The simplest way would be "look for rust". Seriously, iron ore readily oxidizes to form iron oxide (rust), so there will be the characteristic reddish color of rust wherever you have iron ore. StuRat (talk) 02:29, 12 November 2009 (UTC)

Actually most iron ores are oxides or oxyhydroxides and are pretty distinctive - haematite and goethite are rust-coloured, limonite is yellow-brown and magnetite is distinctly metallic. Mikenorton (talk) 23:45, 12 November 2009 (UTC)

That sounds reasonable. I was curious but noticed the relevant articles lacking in any indication of how iron ore was identified before modern geological techniques. Thanks. The Seeker 4 Talk 15:01, 12 November 2009 (UTC)

Do crocodiles care for their young? (Schnappi)

Do real-life crocodiles care for their young? Schnappi's parents do, but Schnappi is make-believe. Mike R (talk) 20:06, 11 November 2009 (UTC)

To certain extent. The mommy corcodile carry her offsprings in her mouth untill they are mautre enough, before that, when they are still in the lair, she come immediately when they sound stress signals. However, when they are mature she send them away, and they better keep it this way for their own safty.--Gilisa (talk) 20:53, 11 November 2009 (UTC)

There's a short passage about it in a book on crocodiles here. They guard the nest, etc. It's mainly the female, but the male chips in occasionally. Fences&Windows 03:02, 12 November 2009 (UTC)

Diet of crocodile hatchlings (also Schnappi related)

Do real-life baby crocodiles eat flies, like Schnappi does? Flies are Schnappi's favorite thing to eat. Mike R (talk) 20:33, 11 November 2009 (UTC)

Nile_crocodile#Diet_and_eating_behavior mentions hatchlings do eat insects among other things. I don't know if that includes flies specifically, but I doubt they are very picky. Rckrone (talk) 21:51, 11 November 2009 (UTC)

Thank you for the link to Nile crocodile. I had just looked at Crocodile and found it lacking. And Nile crocodile is Schnappi's species (Ich bin Schnappi, das kleine Krokodil / Komm aus Ägypten, das liegt direkt am Nil)

I've added Nile crocodile to Crocodile#See_also Mitch Ames (talk) 00:43, 12 November 2009 (UTC)

I've removed it, see the article talk page Nil Einne (talk) 11:43, 13 November 2009 (UTC)

Incidentally, if you have more than one closely related question (in this case all your Schnappi related questions), it's better to post them together. If, on the other hand, you have totally unrelated Q's, then post them separately. StuRat (talk) 14:59, 12 November 2009 (UTC)

Okay, I will remember that for next time. I did have some Schnappi questions for the Entertainment desk, and others for the Science desk -- I assume those should remain separate, correct? I love Schnappi. The Hero of This Nation (talk) 17:47, 13 November 2009 (UTC)

Sure, if you have both entertainment questions and science questions. StuRat (talk) 23:24, 13 November 2009 (UTC)

November 12

Distance

I would like to know what the distance is from the Congo to New Orleans? 00:06, 12 November 2009 (UTC)67.48.17.69 (talk)

According to indo.com, the distance from Kinshasa to New Orleans is 7294 miles. Of course it depends on what point on the Congo you are asking about. Looie496 (talk) 00:33, 12 November 2009 (UTC)

Also see this (unless you mean Congo Square :) hydnjo (talk) 00:56, 12 November 2009 (UTC)

Laser apperance

What causes that strange grainy look that the light produced by most commercial lasers has? Horselover Frost (talk) 00:17, 12 November 2009 (UTC)

Laser light is normally invisible, as it is coherent light that's being aimed somewhere other than your eyeball. If there's dust or fog in the air, the tiny particles of dust or fog scatter the light so that some of it enters your eyeball and you can see it. That grainy look is because the person operating the laser has tossed some dust in the air so that you can see the laser beam. Comet Tuttle (talk) 00:20, 12 November 2009 (UTC)

I should have been more specific. I'm aware laser light in the air is invisible (I'm the one shining the laser). I was referring to the light reflected off a surface. I.e. I take a laser and shine it at a wall, the spot it makes has a grainy appearance, as opposed to, say, shining a flashlight on the same wall. Horselover Frost (talk) 00:25, 12 November 2009 (UTC)

I would guess (and this is just a guess) that it is because the wall is uneven. Different parts of it reflect differently, resulting in the grainy appearance. When you shine a flashlight at a wall each bit of the wall is illuminated from different angles from different bits of the flashlight. That means what you see is an average of how that bit of wall reflects from different angles. That results in a more even appearance. --Tango (talk) 00:40, 12 November 2009 (UTC)

See speckle pattern. TenOfAllTrades(talk) 00:49, 12 November 2009 (UTC)

I have always observed a laser spot striking a surface to look different from a simple focussed light beam of the same size, hue and brightness striking the same surface. The interference of the "speckle pattern" article seems like a plausible explanation. Edison (talk) 00:45, 13 November 2009 (UTC)

A-A bonds are weaker than A-B bonds, which are in turn weaker than B-B bonds

So would a small amount of A be weakly soluble in B, before a separate phase of pure A starts accumulating?

Basically I want to also connect this to the idea of polar covalent bonding versus Van der Waals. Thus, are polar compounds always slightly soluble in nonpolar compounds, but not the other way round? That is, if you had a phase diagram of say, oil and water, you might find an oil+water single phase at maybe 0.1% water by volume, but after that, water starts accumulating as a separate phase. However, oil can't break hydrogen bonding, so oil never dissolves in water, not even at 0.001% levels.

Say you had a eutectic solution of alpha + beta phases, which are solutions of A and B. Could this arise if A-A bonds were weaker than A-B bonds, which were in turn weaker than B-B bonds? John Riemann Soong (talk) 05:43, 12 November 2009 (UTC)

why are eutectic isotherms, well, isoterms?

I don't understand how to get this result from free energy curves... John Riemann Soong (talk) 10:46, 12 November 2009 (UTC)

I don't know this topic, but this seems to address it? Rckrone (talk) 01:47, 13 November 2009 (UTC)

Hollow core conccrete slabs

How are hollow core concrete slabs manufactured? —Preceding unsigned comment added by 113.199.150.180 (talk) 14:26, 12 November 2009 (UTC)

See Hollow-core slab.--Shantavira|^{feed me} 15:38, 12 November 2009 (UTC)

There is no answer of my question. —Preceding unsigned comment added by 113.199.138.211 (talk) 16:53, 12 November 2009 (UTC)

Really? What's wrong with:

Slabs are usually produced in lengths of about 100 meters. The process involves extruding wet concrete along with the steel rods from a moving mold. The continuous slab is then cut according to the lengths required on the construction site. Factory production provides the obvious advantages of reduced time, labor and training.

~ Amory (u • t • c) 17:13, 12 November 2009 (UTC)

(after ec) The article says "Slabs are usually produced in lengths of about 100 meters. The process involves extruding wet concrete along with the steel rods from a moving mold. The continuous slab is then cut according to the lengths required on the construction site." Alternatively, the slabs can be manuafactured with a machine called a slipformer. There is a comparison of the two manufacturing methods here [2]. Gandalf61 (talk) 17:16, 12 November 2009 (UTC)

Social memory

Anybody out there that can give a proper definition of social memory (in psychology)? I've checked Wikipedia, Wiktionary, and about fifteen Psychology glossaries; I've even checked articles with the term social memory as part of the title - yet nowhere a clear definition of what is meant. As far as I understand, social recognition (defined as the process by which an individual recognizes another individual as familiar based on social cues) is part of social memory, but what is social memory?? Lova Falk (talk) 14:54, 12 November 2009 (UTC)

My understanding is that it is the same thing as collective memory. --Mr.98 (talk) 16:06, 12 November 2009 (UTC)

Thank you. However, that may be true in sociology, but it is not in psychology. My question is about a definition of social memory within the individual. This is an example of a short article on social memory. I even checked the article it refers to but even though the authors freely tell that certain mice have intact social memory, whereas others fail to develop social memory, they don't define social memory, apart from an operant definition. Lova Falk (talk) 16:19, 12 November 2009 (UTC)

Please see episodic memory.--Gilisa (talk) 16:57, 12 November 2009 (UTC)

I did, but there is no definition of social memory in episodic memory (or an explanation of what exactly it is.) Lova Falk (talk) 17:12, 12 November 2009 (UTC)

Well, now I may be more helpful after I read the link you provided. I never heard about social memory in psychological context (a side for pseudoscinetific theories such this of Yong)-but in neurobiology reaserch it have a totaly different meaning -in this study they specifically looked at the recollection of social information (and as being done with mice, through smell). It have great meaning to us humans as in different disorders or mental illnesses (such as Autism and Schizophrenia) social and emotional cognition is impaired and so social secens/information (e.g., face expressions) may be stored less efficiently than instrumental information. So, all in all, for the research purposes and to have operative measure, they defined these aspects as "social memory" (and it's a good term, I think)--Gilisa (talk) 17:17, 12 November 2009 (UTC)

• BTW, recent study I'm somewhat familiar with, found higher levels of emapthy in schizophrenic patients who recived oxytocin oraly in a double blind experimental set. So it make perfect sense that they were meaning to memory of social scenes (which are included in episodic memory). --Gilisa (talk) 17:29, 12 November 2009 (UTC)

Thank you!Lova Falk (talk) 19:03, 12 November 2009 (UTC)

The more commonly used term for this is bonding. Looie496 (talk) 19:16, 12 November 2009 (UTC)

No Looie, bonding is not the same as social memory. However, I suppose bonding would be impossible without social memory. Lova Falk (talk) 19:48, 12 November 2009 (UTC)

Indeed, another ongoing study that I'm somewhat familiar with focus on the effects of oxytocin on postpartum depression and many studies have shown that bonding is much dependent on oxytocin. Bonding may be achieved through classical conditioning (in mice cubs, by smell) and social memory as I understand it is more about remembering social hierarchy, acquaintance and etc. Studies in humans have repeatedly found that memory for categories of living things is different from this of items (actually in different brain deficit, different supercategories may be stricken) -memory of items is generally more connected to procedural memory, while memory for living things may have much more implications for the organism and include much more complex demands of detaild memory. For example, returning to mice, there are studies on learned cooperation between a pair of mouse who are locked at the same cage ( with divider between them) and they can get tasty reward only by each of them pressing pedal at the same time with the other-there were also much more social connections between those mice because of the cooperation (it's measured by the amount of subsonic signals they sound)-so this is a classic case for social memory: It was found that entering other mice, instead of one of the two, to the cage ruined the conditioned action of running to the pedal when the light is on: the mice just rememberd who was his original partner and that he was not only an instrument.--Gilisa (talk) 20:21, 12 November 2009 (UTC)

Very interesting! I was actually reading an article on oxytocin when this concept of social memory came up several times, and I wanted to know exactly what was meant. Lova Falk (talk) 21:01, 12 November 2009 (UTC)

Height of a bed

Does it really matter if a mattress lies on the floor or on a bed? Usually it seems the height of the support matters, but bunk beds don't feel different from regular beds. Imagine Reason (talk) 18:21, 12 November 2009 (UTC)

A bed will be sprung (with flexible wooden slats, or something), the floor isn't. That means a mattress on a bed will be softer than a mattress on the floor. The difference is minimal, though, I'd say. Most of the difference is psychological, I expect. --Tango (talk) 18:39, 12 November 2009 (UTC)

It really depends on the mattress, in my experience. I've been on some mattresses that don't seem to let anything through, but I've definitely had my fair shares of sore backs from a mattress on the floor. As a child I never really new the difference until I lost the bunk bed and got an amazing new spring/mattress. ~ Amory (u • t • c) 18:48, 12 November 2009 (UTC)

A bed is important for airing the mattress - and the mattress needs airing to get rid of surplus warmth, and most importantly, for not getting humid. A mattress without a bed or without good airing can start to mould. Lova Falk (talk) 19:08, 12 November 2009 (UTC)

You'll also notice that that are a wider-range of different bed-types, some higher than others, some lower. I would suspect that a huge amount of 'choice' in terms of 'beds' is style/look. I like beds with frames, some people like Divan beds with nothing, some like them with a Headboard, some like Four poster bed and so on. Ultimately whilst there may be reasons of hygiene as per Lova's comment, a large part of it is personal preference. ny156uk (talk) 19:18, 12 November 2009 (UTC)

A bed also gives you a decent amount of extra storage space, which I at least have always found useful. Algebraist 23:27, 12 November 2009 (UTC)

Having a bed at the proper height can minimize the work you have to do lifting or lowering your center of mass while getting in and out of bed, which can be important feeble people. Also beds make sex easier. -Craig Pemberton 01:16, 13 November 2009 (UTC)

"Also beds make sex easier." Yes but at what height? --Jmeden2000 (talk) 17:31, 13 November 2009 (UTC)

As high as they come. Cuddlyable3 (talk) 22:15, 13 November 2009 (UTC)

Emission spectra (II)

Thanks for your help before. Based on the CLOUDY link, I found this which indicates calculation of H and He is possible. Indeed, I then discovered this covering C, N and O. Two points here, firstly it uses the "Case B" exception (a few small assumptions, given usuable range) and secondly it uses "Recombination-line" spectra, which according to this is a type of emission spectra (OK). Can I just confirm that this is, given those points, a calculation of emission line intensities? Secondly, is there any way for me to interpret the data here [3]? Presumably one set of axes (rows/columns) demonstrates the wavelength/frequency and the other some other condition of the emission. If anyone could identify these two things are, I'd appreciate it. Thanks. - Jarry1250 ^{[Humorous? Discuss.]} 19:10, 12 November 2009 (UTC)

question on strength

I am interested if a pipe is equally strong in both compression and tension. For example, If I take a standard straight piece of pipe maybe PVC or something that is part of a much larger system, and can have an internal pressure down to -5 psig before it ruptures, does that mean that it could also hold an internal pressure of 5 psig before rupturing? (For simplicity, ignore everything except that straight piece of pipe. Things like welds or whatever you use to join PVC to other pipe sections, etc). Would the same be true of a metal pipe? Googlemeister (talk) 20:19, 12 November 2009 (UTC)

It doesn't seem obvious that they should be identical...some materials are much stronger in compression than tension - I doubt PVC is is a rare example of something that has precisely the same tensile as compressive strength. Metals certainly don't have that property. I can't imagine any reason for the two to be the same - so unless your pipe is made of some rare, exotic material - then it'll rupture at very different positive and negative pressures. SteveBaker (talk) 20:53, 12 November 2009 (UTC)

Completely different for geometrical reasons as well. But I guess as the diameter of the pipe becomes very large they must converge? --BozMo talk 22:14, 12 November 2009 (UTC)

Why would they converge when it gets large? Think of a balloon - it's strong in tension (pressure), but has zero strength in compression. And conversely you can have something strong under vacuum, but would blow apart under pressure. For example split a pipe lengthwise, and put some rubber (but not glue) on the seam. Now put a vacuum on it - the two sections will be drawn together, and be strong, but would instantly fail under pressure. Ariel. (talk)

I meant the geometrical effect. Anyway, perhaps you are right and when there is a linear failure mode like the one you suggest you are trivially right (I think pipes normally failure in a nonlinear mode via bulging but it must depend on the wall thickness and on the material). I thought Steve was possibly confusing the state of the material (tension or compression) versus the state of gas, or he read the OP as standing on a pipe rather than inflating it? Anyway a flat thin wall fails under pressure by bulging the same amount either way whether the overpressure is left or right. --BozMo talk 23:07, 12 November 2009 (UTC)

Just to nitpick a little, if you had a flat infinite wall with different pressure on either side there would be no stress on it at all. Every part of the wall would be subject to the same force and it would simply accelerate in that direction. It's only when some curvature is introduced that there's stress, since now the forces on various parts of the surface are pointed in different directions. Various parts have relative forces pushing them together or pulling them apart. Rckrone (talk) 06:04, 13 November 2009 (UTC)

Ok, then an anchored flat wall if you must. Which of course when flat is a solution to the stress equations but nonlinearnly unstable if the pressure diff is enough. --BozMo talk 06:41, 13 November 2009 (UTC)

To the OP, pipes are given ratings for vacuum, so you should be able to check. The maximum negative pressure you can have (on the surface of the earth) is about -15psi so it's not hard to find a strong enough pipe. Ariel. (talk) 22:38, 12 November 2009 (UTC)

Whereas of course gas pipes under deep ocean have massive crushing pressure on them. Can you tell us more about what pipe what pressure? I know you are into ships are you after underwater air supply?--BozMo talk 23:16, 12 November 2009 (UTC)

This is not for a practical application. I am just trying to know whether a standard pipe would be more susceptible to failure due to pressure in which direction, overpressure on inside, or overpressure on outside. Googlemeister (talk) 14:31, 13 November 2009 (UTC)

A water. gas, steam, or oil pipe would normally only have to withstand atmospheric pressure of 65.5 newtons (14.7 lb), even with the largest possible vacuum inside, but pipes commonly carry far higher water, oil, or steam pressure inside pressing outwards. Our Water pipe article discusses pressure pipes having thicker walls, but does not answer this question. Sounds like a question for a mechanical engineer, mechanics of materials expert, boilermaker or submarine expert. Sewer pipe is designed to resist external loading. This ref is nearly illegible, but discusses PVC, ductile iron and high density polyethylene as "flexible pipe" which can deflect without failing, compared to clay or concrete which are rigid and fail if they flex. The flexible pipes get an internal and external pressure rating. I can't figure out from the table if they are the same or different. I found a 1913 pipe reference [4] which listed experimental results and empirical formulas for the strength of then used steel pipe subjected to bursting or collapsing forces, but my eyes glazed over reading it before I found comparable pressures for identical geometries, and the results might not apply to modern pipe (and certainly not to PVC). Edison (talk) 21:12, 13 November 2009 (UTC)

Found a modern ref A312 stainless steel pipe. In every case, across diameters and schedules (pressure ratings), the Bursting (internal)pressure was much greater than the collapsing (external) pressure. As the diameters get larger, the ratio of bursting pressure to collapsing pressure gets even larger. Edison (talk) 21:39, 13 November 2009 (UTC)

An online forum I found has engineers sniping at each other in as funny a way as any Wikipedia WP:AFD squabble or edit war, about how to calculate the crush depth of 20" PVC with air pressure inside submerged in water. Their calculations run over a 10 to one range from each other. If the pipe is out of round, it will fail at a much lower external pressure than if it is perfectly round. If it sags between supports, that will hasten collapse. No comparison of burst.collapse pressure for PVC there. Edison (talk) 21:53, 13 November 2009 (UTC)

Farsightness

is Farsightness done by any vision acuity like 20/x or what way is farsightness measur by. Is 20/5 vision a farsightness. Could people be 20/1 vision?--209.129.85.4 (talk) 21:11, 12 November 2009 (UTC)

The definition of "20/x" allows it, and 20/10 has a valid interpretation. And, I've seen one or two (but not all) charts which have 20/15 and 20/10 lines.

"Better" than 20/10 would be a pretty significant distortion of the lens, though. --DaHorsesMouth (talk) 21:45, 12 November 2009 (UTC)

No, 20/x for x<20 means you have better visual acuity than a typical person (my visual acuity is 6/5, or about 20/16, that means that I can see things clearly at 6 metres away that a typical person would need to be no more than 5 metres away to see clearly). That doesn't correspond to farsightedness. Farsightedness will reduce visual acuity, just as nearsightedness does. However, they reduce visual acuity at different distances. What people usually mean by the "20/x" notation is distant visual acuity, but the same notation is used for near visual acuity (although you don't actually measure at 6 metres, you measure at 40cm, so some reason they still call nominal vision "6/6" or "20/20" and scale the numbers appropriately). My optician doesn't write anything down under "near visual acuity" on my prescription, so I guess they only fill it in if you are farsighted. --Tango (talk) 21:58, 12 November 2009 (UTC)

The "far" in farsighted does not mean you can see far away. It means that the lens on the eye focuses too far away from the lens - overshooting the retina. A nearsighted person's lens focuses too near the lens. Regardless of how far away something is that a person is trying to see, not having the lens focus on the retina makes objects appear unfocused. See hyperopia for more info and a clear graphic showing how this is a focusing problem. -- kainaw™ 01:48, 13 November 2009 (UTC)

Kainaw is correct. Farsighted people do not have "better" distance vision (in general) than regular people. Rather, they have worse close vision. Axl ¤ [Talk] 07:32, 13 November 2009 (UTC)

Color vision

Do everyone's color vision work the same or some people's color vision could work differntly? Is this possible people with bad blue sensor can see pink as another color, could some people's human eye be less sensitive for another. Because from my personal observance, when I look at green object for a long time I still able to see green just fine, and white stays white, I see nothing differnce. Is this possible some people when they go to visit planets see colors exactly same as they do on earth, this is what I think I would, or this works for some humans but not the others? —Preceding unsigned comment added by 209.129.85.4 (talk) 21:14, 12 November 2009 (UTC)

is color blindness measur by any numbers like 30 or 100 degres. If people is yellow blind could they see blue as green? Could alot of people have color blindness?--209.129.85.4 (talk) 21:17, 12 November 2009 (UTC)

Have you read color blindness? --Tango (talk) 22:00, 12 November 2009 (UTC)

Not all of us perceive colour the same in the red/orange range,[5] and some women may perceive more colour gradations due to having more than one type of red/green cones; the same thing causes colour blindness in men, because it is X-linked.[6] Fences&Windows 00:51, 13 November 2009 (UTC)

Tetrachromacy is also pretty amazing stuff. SteveBaker (talk) 03:10, 13 November 2009 (UTC)

Does anyone know which materials are used for shielding against infrasound and ultrasound?

Does anyone know which materials are used for shielding against infrasound and ultrasound? Wikipedia articles about sonic weaponry, ultrasound and infrasound unfortunately doesn't say anything about it.

Very grateful for your help

TimmoJTimbboy (talk) 21:30, 12 November 2009 (UTC)

I guess it is the same kind of stuff as is used for other sound proofing. --Tango (talk) 22:01, 12 November 2009 (UTC)

AFAIK Tango is right but it depends how far into fantasy you get. If you mean shielding from sonic weaponry you either need something incredibly strong and rigid (?Chobham armour) or for ultrasound through shock waves something which is flexible (wood, like for construction to survive earthquakes). Generally it needs to be strong in both compression and tension (so steel not brick). --BozMo talk 22:08, 12 November 2009 (UTC)

In case of infrasound, I'm looking for a material, that would be rather easily obtainable, not like Chobham armour. And in the article about sonic weaponry they say about infrasound that armor and concrete walls and other common building (does it include steel, isn't it also a common building material?) materials allow sound waves to pass through, providing little defense.

Thank you!

TimmoJTimbboy (talk) 11:44, 13 November 2009 (UTC)

Well it is a little more complicated than that. Low frequency sound is conventionally considered pretty harmless and the 7Hz referred to in the only reference for the sonic weapon comments is too low frequency to be considered as sound by most people. It will transmit through solid building materials (e.g. as ground shake), but almost all of it is reflected at the interface between air and a solid brick wall for example so it is not easy to fire at a building through air. There have been some studies done on crowd control and low frequency sound though because they can disturb your gut (especially if its full of beer or similar). Can you say anything more about the situation you are considering? Do you live near a railway line and dislike the shake or something? If so little of it will be going through the air. --BozMo talk 12:40, 13 November 2009 (UTC)

I'm living next to a football station, and there has been a couple football riots here, I heard from some locals that the police is planning to use infrasound for crowd control (although I can't be sure if it's true) if something like this should happen again. So, most of the infrasound will be easily reflected by a simple brick? (hope I understood correctly, sorry, I'm not that strong in physics). But why most of the infrasound is reflected and only why only some of it is passing through? Thank you for your help!JTimbboy (talk) 19:00, 14 November 2009 (UTC)

How do we program ourselves?

This question just popped up in my head when I was having a discussion with a friend. When we make a rule for ourselves (let's say, I will turn my head as soon as possible towards whatever direction I hear a sound from), how does this rule translate into an action? There are several things involved here: First I am putting this rule into the brain in some kind of neural language (whatever way the brain understands them), putting in these programs our auditory action, then turning this data into locomotion of our neck. Of course these programs can be made arbitrarily complex (am I right here?). In some cases, the execution will be slower than in other cases. But my question is how this rule is programmed and executed. I know next to nothing about our neural systems. Can somebody explain this taking the above example of rule or another of your own choice. Thanks - DSachan (talk) 22:34, 12 November 2009 (UTC)

For a start look on this then this and finally this. Also, reflexive shifts of visual, but also auditive attention are being mediated by the Magnocellular system.--Gilisa (talk) 22:57, 12 November 2009 (UTC)

The "rule" described by the OP is a function of the Autonomic nervous system that uses the brain structures of the Limbic system which can be called the "reptilian" part of the brain because of its early evolution. One can vary one's sensitivity to sound location mentally either by concentration or distraction. However nobody has to program themselves to be able to do what every living thing that has a brain, ears and a neck is born equipped to do. Cuddlyable3 (talk) 00:34, 13 November 2009 (UTC)

The particular example is unfortunate because it's something we don't need a plan for (I prefer the word "plan" to "rule"), but lets assume a better example could have been chosen, such as immediately striking at a fly if you spot one. It's a really interesting question, and our understanding of the answer is pretty primitive. It's clear that the formulation of plans heavily involves the prefrontal cortex, and that the execution of a plan involves some sort of triggering in the basal ganglia, but it's hard to get much more specific than that. Looie496 (talk) 05:59, 13 November 2009 (UTC)

As I understand it, he was refering to excution of automatic "plans" (e.g., turning your head when someone tap your shoulder) and the not kind of plans that involve with the prefrontal cortex.--Gilisa (talk) 07:53, 13 November 2009 (UTC)

We can give ourselves verbal instructions. These can be the "executive function" which establishes a task "set."[7] I had to climb a tall ladder once to put a chimney cap on a chimney far above the ground. I instructed myself not to jump back if some animal like a raccoon came out of the chimney when I was 30 feet above the ground, since the consequences of a long fall would be worse than getting scratched or bitten by a frightened animal. "Set" is our preparation to selectively perceive something. Perceptual set influences how we perceive ambiguous stimuli, in a hypothetical top down processing system [8]. Some possible interpretations are preferentially activated compared to others. In selecting motor responses (don't jump off the ledge of the building if a pigeon startles or a bee comes at you, shoot if a pheasant swarms up from the ground, run from first base to second if the batter hits the ball) internal instructions might selectively activate some motor responses. Your internally verbalized instructions might have the same priming effect as someone else's statements. For instance if they say "Watch out for rattlesnakes in this tall grass," and someone happens to catch their foot on a vine which makes the grass suddenly move in front of you, you are more likely to jump than if there were no such instruction. You perceptions and response were primed to perceive and avoid snakes. Edison (talk) 14:39, 13 November 2009 (UTC)

November 13

Hollow pipe stronger than solid bar

Is it possible for a pipe of a given substance (metal, say) to be stronger than an equal-diameter bar of the same substance? Interpret "stronger" as you will, though I'm really interested in bending/buckling strength. --Sean 00:32, 13 November 2009 (UTC)

If the pipe is the same material (no special alloying or special hardening) then it is equivalent to the outermost ring of the solid rod of the same diameter, and I cannot see how removing the center of a solid cylindrical rod could increase its strength. For a given weight per unit length, I would expect the pipe to be stronger than a cylinder of the same weight per length but smaller diameter in resistance to bending/buckling, but perhaps not in tensile strength/resistance to elongation. Edison (talk) 00:38, 13 November 2009 (UTC)

For any cylinder, the neutral axis is at the centre. The stress (which is what you're interested in) varies with WxL/Z for a lateral load, where W is the weight, L the length, Z the section modulus. Z = I/C where I is moment of inertia, C is distance from the neutral axis to the most distant fibre. For a shape with outside radius R, C = R, so all that varies is I. I varies with (R^4 - r^4), r being the inside radius. For the solid rod, r=0, so I is maximum - so the solid rod will always be stronger. As Edison notes though, the material near the centre contributes very little to the strength, so in practical terms a hollow shape is much more efficient in material use. If the load is from only one direction, a vertical hollow rectangle will be even better, since I there is WxH^3/12 - w x h^3/12. The buckling (vertical column compression) equations work much the same way, except there you're using radius of gyration. Franamax (talk) 00:53, 13 November 2009 (UTC)

It depends how you interpret "stronger". For example, a concrete cantilever structure is stronger if it is "ribbed", because less of its material strength is "wasted" supporting its own weight. Bending strength of a metal pipe might actually depend on how the pipe is formed - Edison's suggestion that it is identical to the outer ring of a solid cylinder might not take into account anisotropy or lattice structure. There are ASME handbooks that give empircal measurements for these sorts of parameters for pipes of different materials, wall thicknesses and diameters, because theoretical equations are poor approximations to the real material properties. Nimur (talk) 00:59, 13 November 2009 (UTC)

(ec) The above answers are correct – for a homogeneous cylinder, a solid cylinder will always be more resistant to a given buckling force than a hollow cylinder of the same material and outer diameter. A minor caution applies, however, if one is dealing with a long cylinder supported at its ends. In such a case, the weight of the cylinder itself supplies a bending force which can contribute to buckling. In such a circumstance, the strength-to-weight ratio of the cylinder becomes important, and a hollow cylinder may be 'stronger' (in the sense of being able to support a greater externally-applied force) than a solid one. TenOfAllTrades(talk) 01:08, 13 November 2009 (UTC)

Hmm, that's a good point and it could apply to my example of laying a pipe horizontally and putting weight along its length also. For a material of very low tensile strength and very high density, you could have a situation where you have a perfectly good pipe sitting there, then you stick a slug of extra weight into the middle and it nows sags under the combined weight. The smaller diameter piece you stick into the middle couldn't support its own weight, so it would load the pipe, possibly to failure. I'll have to run some numbers on that one. For a column in compression, I'm not convinced, but those formulas are way more complicated, so I might not get to them. :) Franamax (talk) 02:47, 13 November 2009 (UTC)

The OP said "Interpret 'stronger' as you will." If the pipe or cylinder is hanging down from a support and loaded, the cylinder of greater cross section would support a far greater load than the pipe. Likewise, a vertical cylindrical column should support greater weight than a pipe of the same diameter if loaded. If the member is used as a beam, and runs horizontally between supports while supporting a distributed load (like a joist or beam in a structure), only if the supported load is small relative to the weight of the member will a hollow member be "stronger" than a solid one. I agree that it is possible, depending on material , that a hollow horizontal member supported at one end or at the ends might be able to extend farther without collapsing than a solid one, if it were heavy and of low tensile strength (like what? Unreinforced concrete? Adobe? Sod? Playdough? Modelling clay?). I'm not sure that would apply to steel or wood. Joists or beams are solid, not hollow, and that is not a mistake. Edison (talk) 05:16, 13 November 2009 (UTC)

Interestingly, our pipe article has an illustration of wooden pipes, and concrete pipe is very common. Clay pipes are commonly used in many parts of the world; I doubt that they are suspended or supported only by their own material strength. Nimur (talk) 17:53, 13 November 2009 (UTC)

Neither the historic (19th century use) of wooden pipe or more recent use of concrete pipe to carry water or other liquids supports any claim that the pipe is stronger than a solid cylinder of the same diameter, particularly when in compression as a column, where the compression strength of concrete would be great. Unreinforced concrete would not do well in tension, but wood would, and I would vote for the solid cylinder in tension or shear strength. The outermost part would be more effective against buckling or in torsion than the same mass of material located near the center. Edison (talk) 20:59, 13 November 2009 (UTC)

metals and stones

ok, i have several question, but theyre all related to each other, and i did found the general asnwers, but those werent realy specific, especially since my question are actually quite specific anywaysm here goes (by the way, all of the questions are about natural, un-mixed [not artificcially made or alloyed] metals and just natural stones [doesnt matter if its carbon mixed with any other element, as long as its natural])

1. which metal AND stone have the highest melting point?

2. which metal AND stone have the highest (and lowest) density?

3. which metal AND stone have the best heat conduction? (dont answer this one if the answer is silver and diamond)

4. which metal is the hardest (non brittle) and/or toughest (hard to break, crack, bend, or dull) (?possibly based on mohs scale?)

thats it for now, i apologize if this the wrong way to do it, and i want to thank the person who is going to answer this in advance —Preceding unsigned comment added by RoYaLKiD90 (talk • contribs) 01:45, 13 November 2009 (UTC)

Category:Lists of chemical elements is a good start for finding many of the metal properties. Not quite sure what you mean by "not artificcially (sic) made" for metals...almost no metals exist in their "normal, metal form" in nature, but rather as oxides, sulfides, or other minerals and ores. However, Periodic table (standard) tells you which elements are naturally-occurring vs only known via nuclear synthesis in labs. DMacks (talk) 02:55, 13 November 2009 (UTC)

For the lowest density stone, perhaps a pumice stone ? StuRat (talk) 03:05, 13 November 2009 (UTC)

If it has to be a naturally occurring metal then osmiridium is a natural metal alloy of osmium and iridium, high melting and dense. Osmium is the hardest metal and also very slightly denser than iridium, or osmiridium, I am not sure that you will find it pure in nature though. But Osmium is also slightly brittle. reading Thermal conductivity and the condition on your question means that it should not be answered with diamond, but diamond is not actually a metal anyway. And silver is the top metal in thermal conductivity, and also does occur naturally. Graeme Bartlett (talk) 09:37, 13 November 2009 (UTC)

chicken and the egg

Is the DNA of the egg from whence the chicken comes identical to the DNA of the chicken it hatches? 71.100.0.254 (talk) 01:59, 13 November 2009 (UTC)

No. Chickens reproduce sexually, so the DNA of the chick is a combination of the DNA of hen and the DNA of the cock. --Tango (talk) 02:00, 13 November 2009 (UTC)

...er ...No, I don't mean the DNA of the chicken that lays the egg. I mean the DNA of the egg from whence the chicken comes. 71.100.0.254 (talk) 05:33, 13 November 2009 (UTC)

You may also be interested in Chicken or the egg. Red Act (talk) 02:18, 13 November 2009 (UTC)

It is an interesting page, certainly, but it has nothing to do with the OP's question. --Tango (talk) 02:20, 13 November 2009 (UTC)

Are we talking about a fertilized egg or an unfertilized egg? Bus stop (talk) 02:21, 13 November 2009 (UTC)

That depends on why the question was asked. Given the title of the question, I suspect the OP is planning on using a genetic argument to answer the riddle of whether the chicken or the egg came first. Genetically, the answer to the riddle is that the egg came first: Regardless of what precise set of criteria is used to distinguish between "chicken DNA" and the DNA of the chicken's progenitor species, the first egg that contained "chicken DNA" existed before the first bird that contained "chicken DNA". That point is made in the article I linked to.

The "no" part of your answer, BTW, is incorrect. The OP is comparing the DNA of an egg to the DNA of the chicken that comes from it, not comparing the DNA of a chicken to the DNA of an egg it lays. Red Act (talk) 03:14, 13 November 2009 (UTC)

The DNA within the egg is the same as the DNA as the chick that ultimately hatches from the egg. Technically the egg is the zygote - the first cell that forms from merging of male & female genetic material. From the DNA in that cell, the egg and the chick are formed...hence the DNA within the egg is the same as for the chick. On the other hand, the DNA in the egg is NOT identical to the DNA in the chicken that lays the egg because half of the DNA came from the male bird. SteveBaker (talk) 02:48, 13 November 2009 (UTC)

Unfertilized eggs don't contain any genetic material from the male. Bus stop (talk) 02:55, 13 November 2009 (UTC)

And if, perhaps, you asked in order to speculate on the common idiom which came first, the chicken or the egg -- I will respond to that. The question, when posed with thought, may be used to ask how and when evolutionary changes occur. Germ line mutations would allow a a pre-chicken to lay an egg which contains an organism unlike itself, thus it can be said that the [chicken] egg preceded the chicken (and, in essence, the pre-chicken, surprisingly, did not lay a pre-chicken egg). It can also be speculated that the developing, intra-egg pre-chicken developed a somatic mutation (that also affected it's germ-line), thus suggesting that the chicken preceded the chicken egg (because what the pre-chicken laid was a pre-chicken egg). DRosenbach ^{(Talk | Contribs)} 03:55, 13 November 2009 (UTC)

Chicken and egg question is addressed in Scientific American magazine, September 2009, page 77. Bus stop (talk) 03:47, 13 November 2009 (UTC)

The answer I am seeking would be the same answer as if I asked about a caterpillar and a butterfly. Also please clarify about the contents of the egg. It is my understanding that only one sperm enters the egg and therefore the contents of the egg after fertilization leaves no male DNA since it has combined completely with the femaile DNA... but of course what I mean is the combined DNA not to include a remnant of the males DNA. 71.100.0.254 (talk) 06:03, 13 November 2009 (UTC)

A butterfly has the same DNA as the caterpillar that it developed from. In general, the DNA of an animal doesn't change during a metamorphosis.

During sexual reproduction, roughly half of the DNA in the fertilized egg comes from the mother, and half comes from the father. In addition to the articles I just linked to, you may also want to read meiosis. Red Act (talk) 06:33, 13 November 2009 (UTC)

How many nuclei or cells are even in an unfertilized egg laid by a chicken? Are there any? -Craig Pemberton 07:48, 13 November 2009 (UTC)

An unfertilized egg (an ovum), being a gamete, consists of one haploid cell. This is in contrast to a just-fertilized egg (a zygote), which consists of one diploid cell. For a chicken's egg, the nucleus is in the germinal disc, which is that white spot on the yolk. Red Act (talk) 08:38, 13 November 2009 (UTC)

Deaths caused by malaria?

It's easy to find how many people die from malaria per year in modern times but I can't seem to find any numbers for a few hundred years back. I understand malaria has existed for an insanely long time but does anyone know about how many people have died from it in the past few centuries? —Preceding unsigned comment added by 99.230.206.44 (talk) 02:04, 13 November 2009 (UTC)

Since there really wasn't a precise way to analyze total deaths by any disease up until about 1850, it's difficult to give exact numbers. To be honest, I believe the way that diseases like malaria were recorded by text, but not typically, and especially in the most infected lands like Africa. If I were to estimate, I would take the total number of malaria-related deaths in today's population and make adjustments according to population and infectibiliy. For example, if 881,000 people died in 2006 from the disease, I would find the approximate population of a period in time and (do a little math) find the approximate number of deaths that could have occured. It's not precise by any means, but it's better than just guessing right? I hope this has helped!

Try this for information about malaria in general --> WHO malaria website Letter ⁷ 07:33, 13 November 2009 (UTC)

Letter 7, you're suggesting to compare apples and oranges... though I'm not even sure which oranges. :) What is the population you want to compare to which? World population today to world population back then? Not only will you have to rely on wild guesses again (how many people really lived in a specific area at a specific time?), but you also suggest that the same percentage died of malaria. That's highly unlikely assumption. The whole point of malaria medication is to reduce the infection and the death rate. Add to that improved means to protect yourself from mosquitoes (ranging from screens to all the little accessoires that supposedly keep them away), improved health care in general, improved transport (to get health care to people or vice versa), etc. etc. etc. Not to mention that people today live in different areas (more or less exposed to malaria/mosquitoes?), that human activity has had an impact on malaria/mosquitoes, etc. It's actually a pretty interesting question to wonder how much the death rate decreased. But it makes it impossible to assume that the same percentage of the population died, say, in 1700 and today!!

And one more tiny problem to find out "any numbers for a few hundred years back" - malaria is particularly virulent in areas, which "a few hundred years back" simply kept no written records. For example, I don't know if any Sub-Saharan African peoples at all recorded any numbers about malaria deaths before Europeans stepped in (and, BTW, pretty soon started influencing them). So you'll most likely have to look at records of early explorers, missionaries, etc. ... which are most likely seriously flawed (because they commonly only knew a small percentage of the population of today's countries), but it may be your best guess yet... --Thanks for answering (talk) 12:24, 13 November 2009 (UTC)

Also, malaria ranges have shrunk. Washington DC used to be a malaria infested swamp, but I doubt anyone catches it there anymore. Same with most of the rest of the US. It is probably not a common thing to catch in a lot of areas where it used to run rampant. Googlemeister (talk) 14:08, 13 November 2009 (UTC)

Funny you should use that specific example, since there were 2 autochthonous cases near Washington DC in 2002: PMID 12403407 -- Scray (talk) 02:44, 14 November 2009 (UTC)

If you google "malaria 19th century" you get some hits, like this page, that give some indication of what we know about the spread and likely prevalence of the disease in the last couple of centuries. Obviously, exact statistics will not be available for the whole world. (Though for specific countries or regions, they may be—England kept very good death statistics going back hundreds of years.) --Mr.98 (talk) 14:35, 13 November 2009 (UTC)

I imagine you could get very rough estimates of historical mortality rates by studying how much of a population has Sickle cell trait.John Z (talk) 03:34, 14 November 2009 (UTC)

Is this a springtail?

I found this little guy [9][10] in northern Arizona in August. There were several hundred under some pots near a leaking hose so the surrounding loess was damp and shaded. The local region is very arid but there are some reservoirs nearby and scrub and sage not too far out. They were all about 1/2mm long. They could jump about 3cm. I think it might be a springtail but I don't know how to tell for certain. I can't make out a furcula but it is hard to see in the photo. Thank you very much. -Craig Pemberton 03:01, 13 November 2009 (UTC)

If it looks like a springtail and it jumps like a springtail... yeah, I guess it's a springtail :) . --Dr Dima (talk) 03:26, 13 November 2009 (UTC)

My best guess puts it in Entomobryomorpha after looking at a lot of images of springtails. I think I'm confident enough to upload and tag it on commons. -Craig Pemberton 07:51, 13 November 2009 (UTC)

Any springtail that can only jump 3 cm would be laughed out of the club by the other members. StuRat (talk) 11:34, 13 November 2009 (UTC)

Not really, no. Most springtails are tiny, so for some of them 3 cm may well be over 100 times their body length. They can jump several inches, or sometimes less, depending on the species. The peak velocities and accelerations of springtails during the jump are a few times lower than those of fleas, click beetles, and grasshoppers [11]. --Dr Dima (talk) 22:20, 13 November 2009 (UTC)

The fine folks over at bugguide.net identified it as a Entomobrya unostrigata, which I've discovered to be an excellent website for those trying to identify arthropods. Also, I'll pass on this interesting tidbit:

The furca is hard to see in alive specimens since it is held underneath the body when not used. If you tease a specimen for a while and you can keep it jumping it will get exhausted after a series of jumps and then the furca will be visible as a kind of tail behind the body. ---Frans Janssens

-Craig Pemberton 09:49, 14 November 2009 (UTC)

p+ and p- mitochondrial genomes

What do p+ and p- refer to in respect to mitochondrial genomes? ----Seans Potato Business 11:28, 13 November 2009 (UTC)

p+ is a wild type circular mitochondrial DNA, while p- is a mutant DNA.--Gilisa (talk) 13:43, 13 November 2009 (UTC)

I think they are asking which gene is "p" and what is its function. --Mark PEA (talk) 15:57, 13 November 2009 (UTC)

LHC

How the LHC works? When it will start again? —Preceding unsigned comment added by ZrslX009 (talk • contribs) 11:55, 13 November 2009 (UTC)

Did you try LHC which says "Due to the time required to repair the resulting damage and to add additional safety features, the LHC is scheduled to be operational in mid-November 2009.[6][7]" and has a large section at Large Hadron Collider#Design with many links? If you don't already, you'd likely also need to know how Particle accelerators work in general first Nil Einne (talk) 12:10, 13 November 2009 (UTC)

Leukemia transfusions

For patients with luekemia, couldn't they treat it by just doing constant transfusions ? If they don't do this because it would drain the local blood supplies, how about if friends and family (with the proper blood type, of course) provided all the blood ? This would work especially well for pediatric cases, as the quantities of blood needed would be less. I realize that this wouldn't cure the disease, but I would think the patient could be kept alive as long as the transfusions continued. Not a medical advice Q, as I don't know anyone with this disease. StuRat (talk) 15:35, 13 November 2009 (UTC)

Supportive transfusions are a regular part of leukemia treatment. Generally, specific blood components (often red blood cells or platelets, though occasionally white blood cells for immunocompromised patients) are transfused to respond to specific deficiencies, rather than whole blood. Unfortunately, there are issues which would complicate treatment by perpetual transfusion. Patients who receive frequent transfusions of platelets (for example), may develop an immune response to 'foreign' platelets (in appropriate jargon, they are refractory to platelet transfusion: [12]). Finding appropriate HLA type-matched platelet donors is far more challenging than finding ABO-type matches for red blood cell transfusions. Consequently, (potentially-curative) chemotherapy and stem cell transpant are considered a much-preferred alternative to a lifetime of transfusion. TenOfAllTrades(talk) 17:40, 13 November 2009 (UTC)

I've taken the liberty of changing the title of this thread, as it contained a typo, "luekemia" instead of "leukemia". I'm doing this because I'm about to tag the "Luekemia" redirect page for deletion. We don't normally have redirect pages for typos, and I change the title to avoid a redlink.--NorwegianBlue ^talk 21:45, 13 November 2009 (UTC)

I think you are wrong -- we do in fact "normally have redirects for typos". See for example the {{R from misspelling}} template and its associated category. I have removed the speedy tag. --Trovatore (talk) 22:39, 13 November 2009 (UTC)

If you read our leukemia article carefully, you will realize that leukemia is not a single disease. It is a term that includes most or all malignant diseases of stem cells in the bone marrow. Therefore, the prognosis will depend very much on the specific type of stem cell involved, and on the age of the patient. In contrast to many other types of cancer, leukemia is always disseminated at the time of diagnosis. So you have all the problems of a disseminated cancer - a cell population that does not respect our body's normal regulatory mechanisms of cell proliferation. The cells are not localized to a specific area, and therefore not accessible to surgical excision. In addition, there is great variation in prognosis depending on cell type and patient age. Leukemic cells displace normal bone marrow cells. This will, as you address in your question, lead to anemia, and to thrombocytopenia, as TenOfAllTrades says, because megakaryocytes too are displaced. Both the anemia and thrombocytopenia can be treated by transfusion. In countries where leukocyte filtered blood products are mandatory, platelet refractoriness is seen mostly in women who have been immunized through pregnancy. Platelets, in the absence of white cells, are not very immunogenic. A blood center that has a reasonably sized pool of HLA-typed donors and that tests the exact specificity of the HLA-antibodies, will in the vast majority of cases be able to provide matched platelets to such patients. However, the bone marrow suppression also leads to immune suppression, which leads to opportunistic infections, which are a major killer. As TenOfAllTrades wrote, the only potentially curative treatment is chemotherapy, that kills most or all malignant cells, followed by a stem cell transplant. --NorwegianBlue ^talk 23:02, 13 November 2009 (UTC)

Picture of ferrofluid in oil

Hi clever science ref deskers, I'd like to pick your brains about this file: File:Ferrofluid poles.jpg (see thumb). Specifically, the image shows ferrofluid in oil, collecting near the poles of a magnet that has been placed underneath the dish. Although it depends on the strength of the magnet and the magnetisation of the ferrofluid, I've seen that this "collection" happens almost instantaneously. I'd like to find this picture a home in other articles (it's only in ferrofluid so far). Ignoring, perhaps, the fact that it is ferrofluid in oil, what principles are being illustrated here? I have some general ideas, but I'm sure there are some specifics that I'm completely missing, and my captions would probably be wrong, or at least too simplistic. Ideas? Thanks, :) Maedin\^talk 16:31, 13 November 2009 (UTC)

The interesting feature of the picture is the spontaneous formation of corrugations in the black ferrofluid above each end of the bar magnet where the magnetic field exceeds the critical strength for normal-field instability. I think other pictures the OP supplied[13] show this better. This picture shows some unexplained striations in the oil layer that look different at the two ends (poles) of the magnet. I guess these are effects of dispersed grains of magnetic material and surface tension of the oil. Cuddlyable3 (talk) 21:03, 13 November 2009 (UTC)

Yes, I was interested in the striations; I thought this must be a well-known physical property that I just wasn't familiar with. Thanks for your response. I'll try to get in contact with the author and see if he can enlighten any further. Maedin\^talk 17:22, 14 November 2009 (UTC)

On further thought, the ferrofluid may have been initially spread evenly on the surface which was then placed over the magnet. When the ferrofluid was pulled into the shape shown it left tracks of its movement in the oil film. Cuddlyable3 (talk) 18:09, 14 November 2009 (UTC)

Polyploidy in humans

Has any human survived Polyploidy into adulthood? If so, what happens normally? Is Polyploidy in humans considered a "bad" thing to happen? --Reticuli88 (talk) 19:07, 13 November 2009 (UTC)

Did you read our article on polyploidy, specifically the polyploidy in humans subsection? There's a wealth of information there, as well as a link to mixoploidy that notes adult humans with the condition. Whether polyploidy is "bad" depends on the standard you're using, though I don't think it's a difficult question to answer. — Lomn 19:19, 13 November 2009 (UTC)

It doesn't mention anything about adults. When I say bad, I mean is there something physically wrong with the adult who is afflicted with this or is it possible that one can become "super-human? --Reticuli88 (talk) 19:26, 13 November 2009 (UTC)

The condition is almost invariably fatal, and always results in sterility. Superheroes are just as likely to result from polyploidy as from ALS, synesthesia, or radioactive spider bites. — Lomn 19:43, 13 November 2009 (UTC)

Sense of impending doom

Wikipedia seems to have no article for this! It is a well known symptom in many cases, but I can't understand what on earth, biochemically, brings it about. Among other things, I hear blood transfusions (no source) can result in these, along with the classical myocardical infarction, from where I guess it is best known. Any help on this issue would really sate my curiousity; thanks in advance! =) 77.18.86.199 (talk) 19:35, 13 November 2009 (UTC)

Intravenous adenosine injection classically causes this sensation. Interestingly, lidocaine toxicity also causes this. Axl ¤ [Talk] 19:58, 13 November 2009 (UTC)

Anaphylaxis also causes a sense of impending doom (I can testify personally to this). I wonder if it's related to release of epinephrine. --NellieBly (talk) 10:17, 14 November 2009 (UTC)

Malaise tells us almost nothing. I feel one scrapes at the surface of something rather important here, but which is either left unstudied or is just so unpopular to study that the knowledge is not common. My googling efforts continue. 77.18.85.72 (talk) 15:58, 14 November 2009 (UTC)

Classically the rapid dropping blood oxygen from Pulmonary emboli gives a sense of impending doom. See dozens of references for this [14] --BozMo talk 21:10, 14 November 2009 (UTC)

The sensation described by the OP is defined as a foreboding n. a feeling of evil to come. Cuddlyable3 (talk) 12:19, 15 November 2009 (UTC)

EMP

Would an EMP kill humans? After all, we have electrical conductors in our body, yet in COD 6 the EMP detonated seemed harmless to humans. —Preceding unsigned comment added by 24.200.1.37 (talk) 19:52, 13 November 2009 (UTC)

We don't have anything in our bodies that would function as an antenna, so a EMP is harmless (unless you have a pacemaker, I suppose). --Tango (talk) 19:53, 13 November 2009 (UTC)

Electromagnetic weapon#Use against humans. It's not sourced, but it does list some possible side effects of electromagnetic weapons. Presumably how much our neurons were disturbed would depend on the strength of the pulse. It may also affect lymphocytes. ~ Amory (u • t • c) 20:07, 13 November 2009 (UTC)

As I have pointed out on the Science desk in numerous earlier EMP questions, "EMP" is very vaguely defined. In order to speculate about consequences, some parameters must be provided - the power, the duration, the frequencies, proximity to the source, etc. As it is, "electromagnetic pulse" is so vague a term, that the original question is impossible to answer. Every day, nontrivial electromagnetic pulses are emitted by mobile phones, radios, power stations, and other man-made and natural sources of electromagnetic energy. These EMPs are usually entirely harmless. There is a subset which are debated but might be harmful. Finally, at the extreme ends, very powerful doses of ionizing radiation have been shown beyond a reasonable doubt to harm humans. --Nimur (talk) 15:15, 14 November 2009 (UTC)

multiple ccd chips or cameras

If I and my friends (pretend I know Bill Gates and Warren Buffet) bought a lot of maximum megabit ccd cameras and wired their shutters to activate at the exact same moment and placed these cameras in stationary orbit (lets just say next to each other in the least light polluted and most stable place) and pointed each to the same infinite point in space then combined each image with software would this serve in the place of a parabolic mirror to intensify the image and thus allow it to be greatly magnified what magnification would be possible and would this be large enough to justify the project? 71.100.7.164 (talk) 20:04, 13 November 2009 (UTC)

Imaging in weak light of a CCD camera is limited by electrical noise generated on the CCD chip that shows as graininess in the resulting picture. If one can aim many chips at exactly the same object and combine their output signals (with no coding like JPEG in between) then the noise power can theoretically be halved with every doubling of the number of cameras. A practical objection to the scheme is the difficulty of aiming many cameras identically. Having many cameras does not provide greater magnification of the view. For greater magnification the cameras need longer-focus (telephoto) lenses which will make aiming even more critical. The area to be filled by camera bodies would be much larger than that occupied by the parabolic mirror they are supposed to replace. Cuddlyable3 (talk) 20:31, 13 November 2009 (UTC)

Actually what I am suggesting is that because you end up with a combined intensity of the same object which can be aligned exactly by software that because of the increased intensity you can perform the magnification by blowing up only a few number of ccd extremely high resolution cells which represent only a fraction of the object but are visible due to the greater intensity provided by all of the combined images performing the same function as a parabolic mirror. 71.100.7.164 (talk) 22:17, 13 November 2009 (UTC)

You may suggest that software can achieve perfect alignment but that does not make it easy. Enlarging or "blowing up" a CCD image always means reducing the number of cells per printed area. The number of cells on the CCD chip is fixed, as becomes obvious as blockiness (aliasing) when an image is greatly enlarged. If an object is larger than a point source then a few cells likely cover only a fraction of the object. It is unclear whether you are hoping to gain magnification in image size or image brightness. If the subject is stationary then there is no need to have a "lot" of cameras because one can use a single camera to take multiple pictures. A CCD camera coupled to a conventional reflecting or refracting telescope is a popular arrangement for astronomers and makes more sense than coaxing your famously rich friends to buy truckloads of cameras. Cuddlyable3 (talk) 17:59, 14 November 2009 (UTC)

For the sake of argument so as to eliminate the limitations of individual ccd pixels, although grains of silver still present this delimina, the reason for not taking multiple sequential images is to eliminate opportunity for temporal disparity. That said the way graininess is overcome using multiple cameras is by the very fact that they do not occupy the exact same location. The idea is that individual cameras can be designed to use a parabolic reflecting mirror in place of a lens to maximize magnification beyond the ability of the individual camera to distinguish a difference between light levels between adjacent cells due to the extreme magnification and then rely on multiple cameras to contribute to a measurable difference in intensity through image overlay for any wavelength of electromagnetic radiation. 71.100.7.164 (talk) 19:44, 14 November 2009 (UTC)

I believe the OP is referring to something more like an Astronomical interferometer, which is theoretically a quite powerful concept, provided you can get the components in place. Alfrodull (talk) 20:35, 13 November 2009 (UTC)

I would be surprised if the OP was thinking of interferometer because distance measurement is nowhere mentioned. Cuddlyable3 (talk) 17:59, 14 November 2009 (UTC)

You might look at MMT Observatory for a description of a similar idea (six cooperating telescopes) here on Earth. Looie496 (talk) 21:23, 13 November 2009 (UTC)

As our article mentions, there are various proposals for space based inferometers. For example Darwin (spacecraft) and Terrestrial Planet Finder and Space Interferometry Mission [15]. Then there's the rather extreme hypertelescope proposal from Antoine Émile Henry Labeyrie [16]. However these operate using multiple mirrors with one primary imaging sensor and not multiple sensors. And they all are likely to be rather expensive and require a very high degree of technology, in particular the ability to accurately position the multiple elements that we may not currently have. BTW, in terms of multiple mirror telescopes on earth, there are some other proposed ones e.g. check out Extremely large telescope, for example the Giant Magellan Telescope. There is also radical proposed stuff like a Fresnel Imager [17] although again only one camera. Nil Einne (talk) 16:20, 14 November 2009 (UTC)

Yes, mega multiple sensors with individual lenses, shutter and direction control i.e., cameras, is the system which I am suggesting. Has this ever been attempted and if not where can I submit a proposal that it be done? 71.100.7.164 (talk) 17:42, 14 November 2009 (UTC)

71.100.7.164 (talk) 05:53, 15 November 2009 (UTC)

You can send proposals for a new space-based research payload to NASA Ames Research Center or European Space Agency. Expect them to be reviewed by people who know fundamental optics such as diffraction limits, the 300-year history of refinement of the Optical telescope and the already established applications of CCD's in astronomy. You will be at a disadvantage if you cannot quantify your proposal in terms of this body of knowledge. Cuddlyable3 (talk) 12:15, 15 November 2009 (UTC)

has the lhc collided the particles yet

mid-november, we're almost in mid november but theres been nothing on it, this is one of the biggest scientific things to happen and yet theres no fanfare or anything.--Draw99990 (talk) 20:23, 13 November 2009 (UTC)

Both our article and the LHC website say that particles have circulated but not collided. DMacks (talk) 20:31, 13 November 2009 (UTC)

The article says "particles were circulating" as of October 30, but that's really an optimistic way of describing the situation, since particles aren't going all the way around. As of four days ago, they've got particles going half way around.[18] And the first high energy collisions aren't currently expected to occur until sometime in early 2010.[19] Red Act (talk) 20:43, 13 November 2009 (UTC)

You might already know this, but actually discovering new physics at the LHC will require careful analysis of months or years of collected data. There won't be a sudden jump in knowledge on the day the collisions start; there's no "moment of truth". -- BenRG (talk) 22:18, 13 November 2009 (UTC)

The Earth hasn't been swallowed by a black hole yet, so no. :-) StuRat (talk) 23:17, 13 November 2009 (UTC)

They got close - but then (believe it or not) a bird dropped half a loaf of french-bread onto the machinery - which overheated at that spot and shut the system down. So more delays... SteveBaker (talk) 23:17, 13 November 2009 (UTC)

How long does it take a bird to fly here from the future? --Trovatore (talk) 23:19, 13 November 2009 (UTC)

That depends. Is it African or European? —Akrabbim^talk 23:22, 13 November 2009 (UTC)

The LHC, like any other machine, is made of parts that sometimes malfunction and need to be fixed or replaced. This is a normal and anticipated part of the LHC's operation; it's not news. Furthermore, this story wasn't even true, according to this page at cern.ch. The mainstream media is worthless as a source of news about physics. Read physicists' blogs instead. Wikipedia is often good too. -- BenRG (talk) 02:27, 14 November 2009 (UTC)

Looking for Raccoon Penis

Now that I've caught your eye :) Seriously though, I'm preparing a presentation for class regarding raccoon anatomy, and my closer is going to be on this particular "bit". (Why? Keep reading!). I've got just about all of it covered regarding the baculum and so forth, but the thing I can't seem to find is a diagram or even a picture of how the baculum is connected, even which way is "up" on the thing, and how it appears when, errr.... in use, shall we say. All the anatomical diagrams and annotated skeletals I've found tend to omit this little feature. Online searches all return either a story about an unfortunate fellow who tried to get too friendly with a raccoon, or places to buy raccoon penis-bones which are apparently quite popular as trinkets in the Southern US. The latter is why I want to have this as my closer. I found a place that sells bags of the things, so I plan to hand them out to the class as both a visual aid, and as a sort of sociological experiment to see how they are received! :) So.... any ideas? Thanks in advance to all! —Preceding unsigned comment added by 75.227.198.51 (talk • contribs) 21:01, 13 November 2009

The article Baculum may help. You may criticize the speculation noted by Richard Dawkins that the loss of the bone in humans is the result of sexual selection by females. Your post is characterised by nervous euphemisms. A class of children will acquire such an attitude from their teacher. I'm almost certain this is a joke. Cuddlyable3 (talk) 21:45, 13 November 2009 (UTC)

Possible signs of global warming, or just common phenomena?

Hi. I'm in Southern Ontario, and recently this November I've noticed some possible signs of global warming. It is already mid-November, but some things are still occuring that one would expect in the warmer seasons. Just yesterday, I saw several dandelions, both the flowering kind and the white puffballs, as well as those in the closing stage. I also saw a flock of geese (or ducks) flying north in formation. Just today I saw around a hundred birds (either ducks or geese) resting in a small pond (although this isn't very unusual). Within the past week, I and other people in my community have seen ladybugs flying near our homes. Squirrels of different varieties are still commonly seen from day to day. Total precipitation so far this year has been the highest in the past six years, higher even than 2008, which produced a record-breaking summer rainfall and very high winter snowfall, despite having a dry spell in late August and early half of September of this year. We had a short period of warmth this November, being the second-highest recorded temperature in this period of November in the past six years (19C), second only to 2005, globally the warmest year on record. We have had only one minor snowfall this autumn of less than one centimetre, and in previous years snow has often fallen numerous times in late October to early November. Although I have noticed some of these signs in recent years, they appear to be becoming more common. Are any of my observations extremely unusual for my location and time, and could they be signs of global wrming? Thanks. ~AH1^(TCU) 21:47, 13 November 2009 (UTC)

The long-term changes to plant flowering times and to bird/insect migration patterns is certainly a very real, well-documented indication of climate change. They are subtly incidious because many animals and plants have carefully evolved their reproductive strategies around the timing and location of these kinds of event. So if a flower times it's peak nectar production by the average air temperature - but the bees that pollinate them time their spurt in worker-bee production by the length of the day - then the flowers may peak before the bees are ready to pollinate them - the flowers don't get their pollen spread around - and then when the bees do finally kick into high gear - the plants are already past their best. Both species suffer. Similar things happen with bird migration timed against insect hatchings. It's a delicate system that CAN evolve to meet change - but only so long as the change happens gradually and not at break-neck human-induced speeds.

In the flower/bee case, you'd probably just get another species of flower that flowers at a different time thriving at that latitude. We are actually getting that already. StuRat (talk) 23:11, 13 November 2009 (UTC)

The actual weather variations (ironically) are less convincing evidence. Weather is what's happening right now outside of your back door - and it's still sufficiently random to make it very hard to see whether there is a long-term trend. Climate is the average "weather" over large areas and large timescales - and the climate is what is steadily warming. The weather, locally can be unusually cold, unusually wet, unusually foggy...almost anything...because it's only the average that's climbing steadily. Here in central Texas, we've had a record number of insanely hot/dry days this year, leading to severe drought conditions - immediately followed by some of the heaviest rainfall on record...that's the hallmark of changing climate - that records (both highs and lows) tend to get broken more frequently because the weather gets steadily more chaotic. SteveBaker (talk) 22:42, 13 November 2009 (UTC)

OK, but what specifically about the dandelions in November (is this common or extremely rare at my location), and the presense of insects (just yesterday I saw housefly-like insects and what appeared to be a mosquito)? ~AH1^(TCU) 21:09, 14 November 2009 (UTC)

definition of 'oxychemical'

Google is failing me. I have seen the word 'oxychemical' twice today in peer-reviewed papers, but I can't find a definition. Here it is in context, "Fermentation microbiology with renewable resources ... has the potential to produce a large fraction of the oxychemicals and their derivatives that constitute the bulk of feedstock chemicals."

ike9898 (talk) 21:56, 13 November 2009 (UTC)

Oxy<blank> usually means <blank> with oxygen atoms as part of the molecules. See oxyacid, oxyanion, oxyfuel, etc. etc. This likely just means "compounds which contain oxygen". --Jayron32 23:41, 13 November 2009 (UTC)

is anything reproduceable not part of science?

Is there anything reproduceable that isn't part of science? I mean, anything that isn't possible, so despite the fact that it can be shown and is reproduceable, is not acknowledged by science on the grounds of its impossibility. For example, was there a period of time when scientists did not acknowledge the flight of the bumblebee, as the understanding of aerodynamics at the time meant this was not possible? This is obviously just one example, a further example could be the Mpemba effect, specifically when the graduate students told their professor: The technician later reported that the hot water froze first, and said "But we'll keep on repeating the experiment until we get the right result", naturally tihs is a cue for the professor to say "that's okay, forget it", though luckily this did not happen. However, this example, like my first example, suffers from the fact that it is not contemporary. My question isn't whether there is anything reproduceable that wasn't part of science when it was first reproduceable; I'm asking if there is anythin reproduceable that isn't part of science now. So...anything? 85.181.147.202 (talk) 22:31, 13 November 2009 (UTC)

Not sure whether it answers your question but I don't think scientists ignore something just because they can't understand it. I don't think anyone ever refused to acknowledge the flight of a bumblebee. It's absurd to suggest that it's not actually flying, just because they haven't figured out the physics behind it. ----Seans Potato Business 22:59, 13 November 2009 (UTC)

The bumblebee thing is a myth. Science always accepts what can be measured and reproduced on demand under controlled conditions as "The Truth" - if the truth (such as that it's bloody obvious that bees can indeed fly) contradicts theory (that bees do not conform to the current theories of aerodynamics) - then we accept that the theory must need some adjustment. For example - just today there was a piece on www.slashdot.org talking about the Pioneer anomaly (a totally mysterious speedup of the Pioneer spacecraft as they left the solar system). The reason for this speedup is completely unknown and it appears to be breaking one or more scientific theories that we believe to be true. The phenomenon is only somewhat reproducible - some spacecraft have experienced it - others, seemingly, have not. ("While Galileo and NEAR had appreciable speed increases, Cassini and Messenger did not. Rosetta itself gained more speed than expected from its 2005 fly-by, but only the expected amount from its 2007 fly-by.") Until we figure out the cause (and there are plenty of hypotheses out there) - and do some more experiments, the best we can say is that we cannot currently explain the speedup. There could be several reasons for that:

• That one or more of our key theories (relativity, perhaps) is subtly incorrect. It would have to be a very, very subtle error though because these theories are extremely well tested.
• That there is some completely new phenomenon that we're unaware of (perhaps an undetectable source of gravitation outside of the solar system that's attracting these probes...but perhaps gremlins!)
• That there is some kind of error in the experimental data - which is why they're trying to use the Rosetta craft to do more precise measurements.
• That there is some enormous conspiracy to fake the Pioneer data...just like they faked the moon landings. (No, I don't believe that - but you can bet some conspiracy nut does).

I'm sure there are lots of things like that - that's how we end up with theories of Dark matter and Dark energy. Things we know are there because the experimental data says so - but for which we have no really good explanation yet.

You're kinda phrasing your question as if this somehow points to a horrible flaw in "Science" - when in fact, this is modern science's single greatest strength. In the last couple of hundred years, we've come up with a system for doing science that pretty much guarantees that we don't get into the kinds of horrible mess you describe with the Mpemba effect. Serious scientists most certainly DON'T keep doing an experiment until by chance it comes out the way we want. But more than that - scientists THRIVE on finding something that doesn't fit the present theories - that's the way we make progress. When every new fact fits perfectly into what we know - it's kinda satisfying that it's more evidence that we got it right - but nothing CLOSE to the joy of making a discovery that totally overturns some major theory. Everyone thinks Einstein was a genius and a hero for overturning Newton's laws of motion that had stood the test of time for hundreds of years. Einstein is considered to be one of the greatest humans ever to have lived because he found a serious problem with the status quo of science and overturned it. That's why everyone has gotten so excited over the Pioneer effect. It's an opportunity to refine what we know - and for some smart chap to make a name for himself.

SteveBaker (talk) 23:00, 13 November 2009 (UTC)

Sorry, thanks for the responses but I really did mean what I say: something reproduceable that science ignores on the grounds of its impossibility. Examples would be: any effect from a dilution (homeopathy) where the solution has been diluted so many times with distilled water that chances are there is not a single molecule of whatever you started with. Other examples would be telepathy, etc. By the way, I'm looking for an ACTUAL example, if anyone has one...instead you offered a scientific EXPLANATION for why such an example would not exist. Now the following sentence will blow your mind: if someone offers an example of something science ignores on the ground of its impossibility, will you accept this example despite your theory of its impossibility as outlined above, SteveBaker?  :) —Preceding unsigned comment added by 85.181.147.202 (talk) 23:32, 13 November 2009 (UTC)

Homeopathy is NOT reproducable. No controlled study has ever shown that homeopathic remedies produce any results above that of the placebo effect. Likewise, there have been dozens of controlled experiments on things like telepathy, which have turned up bubkis. The experiments on all of these things have been done. People are surprisingly willing to go through the trouble to do controlled experiments in these cases; which is good. Science shouldn't find any possibility off-limits, even though reasonable people would expect the negative result. Most of the time, the negative result is what happens anyways, but on a rare occasion, something interesting happens. --Jayron32 23:39, 13 November 2009 (UTC)

Other than homeopathy, can you think of anything that is reproduceable yet ignored by science? 85.181.147.202 (talk) 00:25, 14 November 2009 (UTC)

The success of the homeopathy is due to the placebo effect, selective memory, and clever marketing. All of which are well understood by modern science.

However, if you must have an example : Scientists have never adequately explained how Santa Claus delivers presents and/or coal to all the Christian children (and quite a few others) in a single 24 hour period. Yet it demonstrability happens every December between sundown on the 24th and sun-up on the 25th.

That's not to say that scientists always have a good an correct explanation for things, just look how long they thought light was carried by aether.

APL (talk) 04:21, 14 November 2009 (UTC)

That slashdot post you're quoting unfortunately confuses two different phenomena: The Pioneer anomaly is an unexplained slight additional acceleration of spacecraft in the direction of the sun, as the spacecraft head out of the solar system. The flyby anomaly is an unexpectedly large increase in the speed of a spacecraft during a gravitational slingshot maneuver. The reasons for the two kinds of anomaly may or may not turn out to be related, but the circumstances under which they occur are very different. But the main point of your post is valid, in that the existence of neither anomaly is being denied by scientists due to a current lack of a good explanation. Red Act (talk) 00:41, 14 November 2009 (UTC)

That is almost a contradiction in terms. To a very large extent checking whether something is reproducable is to engage in science. If you are saying homeopathy is reproducable you are in clear contradiction with the tests scientists have performed. Dmcq (talk) 00:34, 14 November 2009 (UTC)

No - by definition. 70.112.96.57 (talk) 00:36, 14 November 2009 (UTC)

And scientists haven't ignored Homeopathy - check out our article and you'll see any number of studies have looked for an effect and found NOTHING. So this is not a case of science ignoring something that's real - it's a case of a lot of charlatans trying to sell gullible consumers bottles of plain old water for prices that hover around $10,000 per gallon. Science has very carefully examined the claims - and they are not reproducible. Ditto telepathy, ditto all of that bogus stuff. Now you could claim that science turns it's back on what it doesn't understand - but that's demonstrably not the case - (case in point - the anomalous speeds of the Pioneer probes that I mentioned earlier). When the effect is real and can be reproduced under careful conditions - science treats it with respect and no small amount of excitement. When the effect isn't there - then it may be checked carefully and then safely ignored as bullshit...homeopathy being an excellent example of that. Cold Fusion is a good example of this. When some seemingly respectible scientists said they had this amazing effect - everyone got very excited about it. People tried hard to reproduce it - and when they couldn't - the whole thing dropped out of the realms of hard science and into the loving arms of the awaiting crackpots. The trouble is that the layman who does not understand the process sees cool idea after cool idea rejected by scientists. Perpetual motion would be cool - damn you scientists who showed that it's impossible! As science has gotten better and better at it's description of how the universe works - it's inevitable that the number of times we find an exciting and interesting anomaly gets smaller and smaller - and the excitement when we do gets bigger and bigger. In the 1800's an object moving a fraction of a percent faster than you expected was nothing to write home about. In 1900 - it would have been a curiosity worth remarking on - but nothing more. In 2000 - it's a major issue that we're about to invest a lot of time and money to track down and properly explain. Give it another 100 years and finding things that seem to outright fly in the face of existing theories is going to become very tough indeed. 70.112.96.57 (talk) 00:36, 14 November 2009 (UTC)

I can sort of think of an example, but I don't really think it counts. Way back when physicists were first discovering the concept of splitting an atom and atomic bombs, there was a big get-together. It was decided that the calculations made giving the mass needed to create a working bomb should be withheld due to the potentially dangerous uses. This didn't last long for a lot of reasons, least of all pride but especially since it became obvious that there were other, harder issues (the trigger, par exemple). Still, it was ignored so much as it was hushed for a little while. As the editors above say, if it's reproducible it's not ignored. It may not be widely studied at the moment, but those are issues more related to funding and interest. ~ Amory (u • t • c) 00:45, 14 November 2009 (UTC)

The failure of any party to claim James Randi's prize goes a long way to dispelling the notion that science might behave in such a way. -Craig Pemberton 02:24, 14 November 2009 (UTC)

Fun fact : The bumblebee thing is a myth. The boring truth is that one scientist made an error in a back-of-the-napkin calculation during a dinner party. His biologist collieges spread the story far and wide, because if there's one thing biologists love is to prove that they're smarter than those smug jerks from the physics department.

The "Fact" that bumblebee's can fly was never based on accepted actual, current, scientific thought. APL (talk) 04:11, 14 November 2009 (UTC)

In terms of the Mpemba effect, while I've read multiple conflicting claims about precisely what happens it's my understanding that the issue is that it was something that few scientists had studied or were aware of at the time and while it was known by some lay people, it's apparent that many people were not aware of it. No one demonstrated it to any scientist and since it seemed unlikely, many dismissed it when people claimed it was the case. I'm sure many scientists get people making claims which are made up, delusions or simply the result of poor methodology so it's hardly surprising that many scientists will dismiss such claims off hand without any evidence. However I'm not even aware any scientist did dismiss the claims, Mpemba was a secondary school student and he told his teacher who did dismiss it (and possibly made fun of him as a result of that) and while the teachers actions are perhaps not uncommon although also perhaps not a good thing, I'm doubtful that the teacher would fit most definitions of a 'scientist'. The first scientist who he did tell (that we're aware of) did not in fact dismiss the claim and instead asked a graduate student or technician to test it. Whatever the student/technician really said (and I suspect it's unlikely we'll ever really know) the basic idea was sound, an extraordinary claim requires extraordinary proof so many repetitions were necessary before they took it any further. Had anyone publicly demonstrated the Mpemba effect it wouldn't surprise me if it would have attracted more interest and similarly someone who would not normally be considered scientist could likely have published a paper on it if they went about it the right way and put a bit of effort into it. In other words, it's not something that scientists didn't accept rather that they simple weren't aware of and wouldn't likely not have accepted without good evidence since it didn't fit with theory Nil Einne (talk) 09:19, 14 November 2009 (UTC)

You may wish to consider the work of Rupert Sheldrake, in particular "The Sense of Being Stared At", as part of the answer to this question. --TammyMoet (talk) 15:20, 14 November 2009 (UTC)

What type of soda?

Hello desk. I am trying to make ink using a method found in some ancient Nepalese scrolls. The translation says at one point: "If one puts soda in boiling tea, this melt is said to be the best binder for ink." I finally found out what the glue liquid it keeps referring to is made up, but I don't know what type of soda the scroll refers to. According to the soda disambiguation page, it could be sodium oxide, sodium hydroxide, sodium carbonate, or sodium bicarbonate. I also see that sodium hydroxide is used in the bleaching of wood pulp. Since we're making (black) ink from fungal spores, perhaps this means it is not sodium hydroxide, or lye? I believe in another portion of the scroll it states that the same solution will congeal when it cools. What soda do you think it could be? Also, is the tea important, or do you think boiling water would be chemically sufficient? Thank you for any help! Mac Davis (talk) 22:37, 13 November 2009 (UTC)

If the solution "congeals" - then one needs to know how strong it is. Sodium Carbonate (the "normal" use of the name soda these-days) will form a decahydate - so 105g of sodium carbonate combines with 181g of water - this will melt at just 34°C - so one would not see any solid until the solution was below that temperature - so say 1 part sodium carbonate with 2 parts water will almost set solid at ambient. Sodium hydroxide is very soluble - 100g in 100g of water would be a solution which would start to crystallize at room temperature. Sodium bicarbonate is not very soluble, it will start to crystallize at ambient about 8% strength - but just throws down a white solid. My best guess is Sodium carbonate.  Ronhjones  ^(Talk) 23:02, 13 November 2009 (UTC)

Actually I think the "normal" use of the word soda is as shorthand for soda pop. Depends on where you live, of course. Somewhere you can find a map of the US and Canada, divided by where they say soda and where pop. --Trovatore (talk) 02:21, 14 November 2009 (UTC)

And they are "fizzy drinks" over here. Much more logical, we Brits are...  Ronhjones  ^(Talk) 18:41, 14 November 2009 (UTC)

Say what? I ordered a lemonade over there, and they brought me some nasty Sprite or something. --Trovatore (talk) 20:09, 14 November 2009 (UTC)

That sounds perfect Ronhjones! According to the article it is used as a bonding agent in alginate and can be easily extracted from the ashes of any plant. Mac Davis (talk) 00:31, 14 November 2009 (UTC)

That makes it even more interesting... See Potash - Plant ash would be initially potassium hydroxide, but that would rapidly absorb carbon dioxide (on cooling) to make potassium carbonate. So if the main source is plant ash then I'll plump for potassium carbonate (but there's a good chance sodium carbonate should work just as well in your application).  Ronhjones  ^(Talk) 18:38, 14 November 2009 (UTC)

Two girls, one baby (or two guys, one baby) - artificially fertilising an ovum using two ova nuclei or to sperm nuclei

Am I correct in thinking that parental imprinting would prevent the development of ova (with their original nuclei removed) fertilised with nuclei from two sperm or with the nucleus from other ovas? I expect that certain required genes would not be expressed in the correct ratios because the patterns would be the same in both sources and therefore not complementary? ----Seans Potato Business 22:52, 13 November 2009 (UTC)

Yup. I gave a pretty complete answer to this same question half a year ago: Wikipedia:Reference_desk/Archives/Science/2009_February_12#Same-sex_gametes_combining_to_form_a_zygote.3F. Someguy1221 (talk) 23:12, 13 November 2009 (UTC)

The Genomic imprinting article also describes experiments with mice to this effect. Rckrone (talk) 23:25, 13 November 2009 (UTC)

What would happen...

What would happen if less than half of the universe was nothingness? jc iindyysgvxc (my contributions) 23:05, 13 November 2009 (UTC)

It was, for part of its history. See Timeline of the Big Bang and the subarticles on the specific "epoch's" during the first few seconds. --Jayron32 23:32, 13 November 2009 (UTC)

It would rapidly collapse in a Big Crunch. That said, I don't think it is possible for the universe to reach its current size and age with that kind of density (in fact, it may not be possible for it to have that kind of density anyway - one of the results of inflationary theory is that the density of the universe will inevitably end up close to the critical density, and that theory seems to be well supported by evidence). --Tango (talk) 02:55, 14 November 2009 (UTC)

Which half? The left half or the right half? :) For some people with brain injury, see Hemispatial neglect, one side of the universe to all intents and purposes disappears and they don't seem to notice much. 12:09, 14 November 2009 (UTC)

November 14

Blood Type Compatibility

Just forestalling any possible misunderstandings, this IS NOT a request for medical advice. And now that that's out of the way, the question: Is it possible (I have heard stories places) to determine whether two people are compatible to donate blood to each other by having each prick their finger and mixing their blood on something like a microscope slide, then watching to see if it clots like crazy? Ks0stm ^(T•C•G) 03:53, 14 November 2009 (UTC)

No, it's not that simple. For one thing, clotting, or the production of a blood clot, is distinct from the agglutination reaction that indicates incompatibility. Second, while agglutination is a clear indication of incompatibility (for one or both potential recipients), more sophisticated tests are needed to ensure compatibility. -- Scray (talk) 04:31, 14 November 2009 (UTC)

Schrödinger's cat - can you actually stop observing it?

With respect to the Schrödinger's cat thought experiment, is it possible, even in theory, to set up a situation where a cat is not observable?

As a thought experiment, the Schrödinger's cat scenario is not constrained by practical limitations, but does it even make sense to have a cat so completely cut off from the rest of the universe that it is not observable, even in principle? I am curious specifically about the fact that a live cat, in contrast to a dead cat, has a metabolism generating heat, has a heartbeat, has a nervous system with electrial currents, etc., and must therefore be continuously interacting with the universe at large. I realize that the point of the thought experiment is to demonstrate the paradox, but discussions always gloss over this point. Peter Grey (talk) 06:05, 14 November 2009 (UTC)

Different assumptions would make it a different scenario. -- Scray (talk) 06:12, 14 November 2009 (UTC)

It's not necessary for the cat to be completely isolated from you, only that the effect it has on you is something that could have been a consequence of either state. I think enough insulation, or just being far away from the box would make it work. Even with full knowledge of the initial state of the system, \there will be a wide range of possible observable outcomes for each the live and dead cat. If what you observe is in the intersection of those two sets of possibilities, then the cat is to you still in a superposition of both alive and dead. Once you observe something that couldn't be caused by one of the fates of the cat (or is extremely unlikely to be caused by one of them) then you're entangled with the cat's alive/dead-ness and to you the cat is definitely alive or definitely dead. Rckrone (talk) 09:32, 14 November 2009 (UTC)

It'd pretty difficult with an object the size of a cat, never mind the ethical issues. There are proposals though to do the equivalent with a virus. Not quite so impressive having a 'Schrödinger's virus' but few people will worry about its fate. Dmcq (talk) 12:03, 14 November 2009 (UTC)

Paper here. Apparently they propose to maglev a small object like a virus and cool it down to the ground state of quantum harmonic oscillation, then put it into a superposition of the ground state and the first excited state. They don't create a superposition of internal states of the virus, much less a difference as complicated as "alive" and "dead" (whatever that would mean for a virus). This experiment is only possible because viruses are inert hunks of matter when they're not infecting a cell; you couldn't do it with a living cell because of all the chemical activity going on inside (I think). Also, a superposition of ground and first excited states is only a "superposition" in the sense that it's not an energy eigenstate. But complicated systems are never in energy eigenstates anyway. The cooling to the ground state seems more interesting than the subsequent excitation, which just makes it slightly more normal again. Nevertheless, if this experiment is performed, it will of course be reported by the media as "an experimental realization of Schrödinger's cat". -- BenRG (talk) 13:15, 14 November 2009 (UTC)

In practice it is absolutely impossible to shield something of the size and temperature of a cat from the outside world. All that's necessary for the system to become classical is that the environment contain enough information to distinguish the states in principle—whether or not that information is accessible in practice—and that's inevitable when enough particles are involved. The heat radiating from your computer case contains information about the calculations being performed by the CPU. If nothing else, the cat's gravitational field will give it away through any amount of insulation, I think. Even if the system's state remains unknown to you, you still have to model it as a classical mixed state (1/2 chance of live cat, 1/2 chance of dead cat) and not as a quantum superposition (1/√2 alive + 1/√2 dead) to reflect the fact that it has objectively collapsed by environmental decoherence. -- BenRG (talk) 13:02, 14 November 2009 (UTC)

Maybe you could set up noise around the cat, like randomly moving weights, sounds, etc, determined by a lot of different quantum measurements. Would it be possible to create enough noise so that from your perspective it would be impossible to distinguish the two cat fates even in theory from the observables available to you? Rckrone (talk) 17:23, 14 November 2009 (UTC)

Unless I'm missing something, that's impossible. Because of unitarity, the only way to eliminate the information from the environment is by, in effect, undoing the process that produced it. If that was a thermodynamic process (like blackbody radiation) then you can't undo it because of the second law. -- BenRG (talk) 18:00, 14 November 2009 (UTC)

The wave function is fully determined, but when you take a measurement, you aren't finding the full wave function. Two different wave functions can produce the same measurement. That's the idea behind interference. Rckrone (talk) 18:42, 14 November 2009 (UTC)

Noise doesn't do it. It may make it harder, or perhaps impossible to determine which information comes from the cat, and which information comes from the noise, but the information is still leaving the box. APL (talk) 21:23, 14 November 2009 (UTC)

Right, but it's not enough for information to be leaving the box, it has to be information that is determined by the fate of the cat. If the same measurement could as likely come out of the box with a live cat in it as the box with a dead cat, then making that measurement doesn't lead you be entangled with the cat's alive/dead state. BenRG is right that the measurement you're making includes any way that the box affects you which includes quite a lot of information, but I'm wondering if it wouldn't still be realistically possible to set up the box so that the measurement isn't necessarily indicative of the cat's state, at least for some short amount of time after the event. Rckrone (talk) 22:02, 14 November 2009 (UTC)

In principle it's very simple: you put the cat (in a box) in the middle of interstellar space, with the closest observer a billion miles away. The cat is then unobservable over the time course of the experiment simply because of the finite speed of light. Looie496 (talk) 18:38, 14 November 2009 (UTC)

origin of a cyclone

formation of cyclones —Preceding unsigned comment added by 124.43.90.158 (talk) 08:32, 14 November 2009 (UTC)

Are you asking, "How does a cyclone form?" If so, see Cyclone#Formation.--CurtisSwain (talk) 08:59, 14 November 2009 (UTC)

Ferrofluid buoyancy?

Supposing a powerful (perhaps superconducting) permanent magnet was placed over a tube of ferrofluid. Would pressure still increase with depth, and what would happen to an object of neutral buoyancy in such a liquid at different depths?Trevor Loughlin (talk) 14:19, 14 November 2009 (UTC)

It would depend on if the magnetic "up" force more than counteracted the gravity "down" force. Pressure in a liquid (condensed fluid) is just controlled by the forces acting on the fluid (gas pressure works differently). Under normal circumstances, gravity is the only force acting on it. If you had a stronger force pulling straight up, such that the net force vector on the fluid was up rather than down, I would expect the pressure gradient to act differently. Of course, since the magnet will lose strength with distance, this effect could result in some unusual pressure gradients. --Jayron32 16:05, 14 November 2009 (UTC)

Having neutral buoyancy by definition means an object neither rises nor falls from its position in a presure gradient. Cuddlyable3 (talk) 16:36, 14 November 2009 (UTC)

Supposing the magnet was strong enough to completely reverse the pressure gradient. Would an object which would normally float upward float downward? And if it was moved sideways out of the gradient (since the float is not magnetic itself this takes little energy) when it reached the bottom, would it float up again? And if it was moved sideways back into the reverse gradient when it reached the top, would it sink again, creating a mechanical over-unity device?Trevor Loughlin (talk) 12:37, 15 November 2009 (UTC)

Hanging

The OP is asked not to edit responses to their question. Cuddlyable3 (talk) 23:25, 15 November 2009 (UTC)

how come profesional hangings the victom goes out quick even if the neck is not broke iv watched 30 iran and german hangings they are all instent alothough they are all suspension. but suicide hangings iv seen take at least 10 secs to pass out why?

examples: http://video.google.com/videoplay?docid=7181755851454128977#

http://www.liveleak.com/view?i=317_1218265064

there are many others many in which the are slowly raised by hand as well . the result is the same. why? —Preceding unsigned comment added by 74.65.3.30 (talk) 16:34, 14 November 2009 (UTC)

There are different ways of hanging a man by the neck until he is dead. The long drop, favoured by English hangmen, produced death by breaking the neck. You may also wish to consider whether censorship was applied to the video clips you have been watching: was a long struggle cut from the end result so that it could be distributed? --TammyMoet (talk) 17:33, 14 November 2009 (UTC)

Breaking the neck does not, of course, produce instant death. What it produces is instant paralysis, sparing the feelings of the onlookers; the interested party stops moving, because he can no longer send signals to any muscles below the neck, and usually his face is covered. --Trovatore (talk) 20:53, 14 November 2009 (UTC)

The article Death erection cites from a RS that one in three hanging men have an erection. That statistic means the OP may have watched 10 males with erections but no associated enjoyment. Unless any were female or very very peculiar. Cuddlyable3 (talk) 22:54, 14 November 2009 (UTC)

The OP is asked not to edit responses to their question. Cuddlyable3 (talk) 23:25, 15 November 2009 (UTC)

bipolar disorder

percentage of people affected by bipolar disorder globally and age wise .. —Preceding unsigned comment added by Arun vvv (talk • contribs) 17:29, 14 November 2009 (UTC)

Is the information on epidemiology in our article on bipolar disorder helpful? TenOfAllTrades(talk) 18:53, 14 November 2009 (UTC)

homeostasis during illness

Hello! I've been asked to look at the role of homeostasis in the human body during health and illness. As for health, I thought this seemed quite simple - homeostatic mechanisms such as regulation of blood glucose concentration, blood pressure, serum potassium concentration, osmoregulation etc. help maitain our health and without them we would obviously quickly die. When it comes to the role of homeostasis in illness I got stuck and I need someone to point me in the right direction. What examples of homeostasis occur during illness? Would the mechanism of a fever be an example? Please help! RichYPE (talk) 19:33, 14 November 2009 (UTC)

You might look at CO₂ levels, pulseox and respiratory volume when O₂ is administered. You might look at the blood sugar levels in diabetecs when they have an infection. Edison (talk) 20:18, 14 November 2009 (UTC)

Additional pointers:

• Villous adenoma, anemia, tissue hypoxia, erythropoietin, reticulocytosis, iron deficiency
• Physical exercise, muscle hypertrophy
• Hypertension, ventricular hypertrophy
• Sound, Tensor tympani
• Infection, Inflammation, Chemotaxis, Diapedesis, G-CSF

Hope this helps. -- Scray (talk) 05:46, 15 November 2009 (UTC)

I think perhaps the article on Stress (biology) is the best place to begin. It will point you to other relevant articles, such as HPA axis. Looie496 (talk) 18:15, 15 November 2009 (UTC)

LHC beam dump

The LHC has around 8000 miles of rock and metal around and under it. The beam dump of the LHC has to absorb high particle energies, and needs to be several meters long to do so.

Why isn't the earth itself suitable for absorbing the energies of the beam? It's less absorbent than custom materials (graphite, etc) but there's miles of rock compared to meters of custom material, and a less efficient but longer absorber would presumably spread the heat dissipation over a larger volume. Heat dissipation is its main purpose, and presumably nobody really cares how warm a chunk of off-site rock at the end of a separate tunnel 50 - 175 m underground gets.

FT2 ^{(Talk | email)} 21:00, 14 November 2009 (UTC)

They may care how radioactive it gets. It could well become a safety issue. Groundwater can move radioactive isotopes to unwanted places. Graeme Bartlett (talk) 21:28, 14 November 2009 (UTC)

Rising longevity and the remaining number of years of expected survival

Its 2009, I'm X years old and I've got a 50% chance of surviving for another Y years. Going back 100 years say with a much lower longevity for the population, then to have the same chance of surviving another Y years I would have to be very much younger - I would need to be Z years old. Is there anywhere on the internet where I can see my Z-age (to coin a term) during the 20th and earlier centuries? Or get the data to estimate it? 78.147.25.95 (talk) 21:50, 14 November 2009 (UTC)

I don't know where to point you for the specific data — I could Google it but so could you. But when you find it, I think you may find that the differences are not as dramatic as you think. As I understand it the life expectancy of adults has not really risen that awfully much. The huge increases in life expectancy at birth are largely due to the fact that far fewer people die in childhood than they used to (at least in the industrialized world). --Trovatore (talk) 22:01, 14 November 2009 (UTC)

I've read that idea several times here, but I think its not particularly true. My grandfathers for example died in their sixties probably due to unwittingly consuming too much saturated fat and alcohol and not taking much exercise. In the early 20th. century at least even people who survived childood still died much younger than currently. 84.13.173.43 (talk) 11:53, 15 November 2009 (UTC)

There certainly has been an increase in how long people that reach adulthood live, but it is small compared to the increases in life expectancy at birth. According to Life expectancy#Lifespan variation over time, the average life expectancy at birth in mediaeval Britain was 20-30 years. It is now about 80. That is an increase of at least 50 years. I can't find figures for adult life expectancy, but I think we can be sure it has increased by significantly less than 50 years. --Tango (talk) 12:13, 15 November 2009 (UTC)

Is X=Y in the question or is it a two parameter question? i.e. do you just want the age at which you have a 50% chance of living as long again? By the way of course the chance of you surviving for another Y years is technically unknown since we don't know what will happen to the curve of longevity in the future (obviously). Incidentally an appreciable fraction of all the people who have ever lived are still alive (bout 10-15% I think) which does not imply you have a 10-15% chance of not dying but does illustrate the growth in the population. --BozMo talk 22:09, 14 November 2009 (UTC)

X=Y?? You mean if I'm two years old I'm going to only survive another two years? You've misunderstood the question. 84.13.173.43 (talk) 11:56, 15 November 2009 (UTC)

That last statistic depends heavily on what you mean by "people". You have to draw the line somewhere, but where you draw it can make a big difference (population numbers were low in proto-humans, but they were around for so long that the total numbers are high). We have some discussion of this topic at World population#Number of humans who have ever lived. --Tango (talk) 22:27, 14 November 2009 (UTC)

The questions seems to be about the estimated lifetime remaining, conditional upon reaching a given age. Insurance and census data would be a major source, it would also depend upon other factors such as locale, health, employment, family/medical backgrounds, and so on. The question can be paraphrased (as I understand it) this way:

Holding all other matters constant: - "For any given age of a person (A) and calendar year (B), there will be an age (C) such that a person who is A years old in year B, has a 50% chance of living to C years old. Where can I find a table of (A, B) -> C?"

Or more generally: - "For any given age of a person (A) and calendar year (B), there will be a distribution (C) for eventual age at death vs. probability of dying at that age. Where can I find a table of (A, B) -> C?"

FT2 ^{(Talk | email)} 22:33, 14 November 2009 (UTC)

The article Life expectancy will help. Life insurance companies keep data for life expectancy estimates when selling a Life annuity which is a form of Longevity insurance. Cuddlyable3 (talk) 22:39, 14 November 2009 (UTC)

Life tables typically give you A->C for fixed B. What the OP wants is B->A for fixed C. I don't think that exists ready made. --Tango (talk) 23:39, 14 November 2009 (UTC)

What I'm effectively looking for are life tables for various times in the past. 84.13.173.43 (talk) 12:02, 15 November 2009 (UTC)

November 15

Lucid dreaming

How can I develop this skill? —Preceding unsigned comment added by 79.67.82.206 (talk) 01:10, 15 November 2009 (UTC)

Did you try looking it up on Wikipedia, seeing as you are here? If you had, you would have very quickly found this: Lucid dreaming#Induction methods. --Tango (talk) 02:32, 15 November 2009 (UTC)

Yes thanks dont know how I missed that. Must have been asleep when I asked the Q--79.67.82.206 (talk) 12:12, 15 November 2009 (UTC)

Lucid dreams can be very hard work. It is funny when one wakes up from a realistic dream wherein he worked harder than in real life. I woke up from dreaming about having to devise computer systems for tracking billing and document management for a law firm, and designing a complete physical plant for the firm, all of which were far removed from tasks I ever did in a job. On waking, i felt ripped off, as if I had done work without compensation. Why would you assume lucid dreaming is a good thing? Edison (talk) 03:41, 15 November 2009 (UTC)

If it were really a "lucid dream", you would have known it was a dream, so you could have just told your boss to go jump in a lake. APL (talk) 04:35, 15 November 2009 (UTC)

Indeed. I think Edison is getting confused between "lucid" and "vivid". --Tango (talk) 13:25, 15 November 2009 (UTC)

I don't think you can develop it. There is no evidence whatesoever that these dreams are indeed lucid. As we can dream just about everything, we can also dream that we are lucidly (aka consciously) dreaming, just like we can dream we that we are cold, or hungry or whatever. It's an illusion. DVdm (talk) 13:34, 15 November 2009 (UTC)

Huh? I don't quite follow you -- would there be any empirical difference between actually dreaming, versus merely dreaming that you are dreaming? I have lucid dreams occasionally (not deliberately induced), and I find that I can easily make myself wake up from one if I want to. It seems to me that that's inconsistent with what you're saying, but I'm not sure I actually understand you. Looie496 (talk) 18:09, 15 November 2009 (UTC)

"I can easily make myself wake up from one if I want to." ==> You mean that you dream that you easily can make yourself wake up.

We dream that we can can fly. Do we actually fly?

We dream that we can make ourselves wake up. Do we actually make ourselves wake up? You might think so, but I don't - we just dream it.

We can dream anything, remember, so why not this?

Perhaps this clarifies :-) DVdm (talk) 19:15, 15 November 2009 (UTC)

I lucid dream and sometimes it goes a bit all wrong, and I concetrate extremely hard on moving my real life arm instead of my in dream arm and it wakes up. Like, actually wakes me up in real life. I've done it relatively consistently so it's not just a coincidence. Plus if you're aare you're dreaming then you're aware you're dreaming, surely that's that? 82.11.245.145 (talk) 19:48, 15 November 2009 (UTC)

I don't think so. If you think you are aware you're dreaming then surely you agree that you are dreaming. Now, what are you dreaming? You are dreaming that you are aware you're dreaming. DVdm (talk) 19:50, 15 November 2009 (UTC)

But I'd say lucid dreaming is being aware you're dreaming, and if you know you're dreaming in any sense I'd say you are lucid. Generally realising you aren't awake whilst in a dream would be lucid to me in some way, even if you are dreaming you're dreaming. I get what you're saying, but it seems more philosophical/a technicality than anything. Guess it depends on how you think of the term. Jimothyjim (talk) 20:02, 15 November 2009 (UTC)

Well, starting from the premise that one can dream anything, I just apply Occam's razor in this case. I always found this a school book example.

Cheers, and sweet dreams :-) DVdm (talk) 20:36, 15 November 2009 (UTC)

Nonsense. First of all, in it's purest form, a "lucid dream" is just a dream where you're aware that you're dreaming. There's no difference between being aware of something during a dream, and dreaming that you are aware of something. Perhaps you're objecting to the idea that dreams can be controlled. That's entirely testable. (By the dreamer, perhaps not by an outside observer) People who can lucid dream often decide before they go to bed what direction they'll take a dream in. Since this is typically a direction that their dreams to not normally go in (else, why bother?) and since they are typically satisfied with the results, I deduce that lucid dreamers are getting results far better than random chance.

Incidentally, I'm not sure if this is a correct application of Occam's razor. You're positing an unusual sort of meta-dream. Why does this multiply entities less than positing a lucid-dream? APL (talk) 00:52, 16 November 2009 (UTC)

Hunger

Why do I feel hungry about every 5-6 hours while awake, but not when asleep. When I wake up at night I may feel hungry but if I go back to sleep without eating, then, when I wake up in the morning, Im no hungrier than normally at breakfast. Whats going on here? —Preceding unsigned comment added by 79.67.82.206 (talk) 01:14, 15 November 2009 (UTC)

Circadian rhythm, or something similar - hunger isn't only caused by a need for nutrients, your body is conditioned to expect foods at certain times and not to expect them at other times. Vimescarrot (talk) 01:22, 15 November 2009 (UTC)

Sleep is a pleasure too. You have two competing pleasures — sleeping and eating. Why waste good sleep on mundane eating? Bus stop (talk) 03:47, 15 November 2009 (UTC)

You also have a much larger demand for nutrients while awake since you are actually up and about and doing things. Sleeping doesn't require much energy at all (no walking, no intense thinking), so you can make it pretty far on not very much. ~ Amory (u • t • c) 19:47, 15 November 2009 (UTC)

Phone and Paper Shredder

Many times when I receive a cell phone call in my bedroom where my paper shredder also happens to be, the paper shredder will start running (as if I inserted paper) just before the phone rings and will continue to run until I pick up the call. Why does this happen? 69.115.152.137 (talk) 01:32, 15 November 2009 (UTC)

Do the clocks start running backwards when someone rings the doorbell as well? :) Perhaps it's interference. DRosenbach ^{(Talk | Contribs)} 03:10, 15 November 2009 (UTC)

...don't you love flippant responses? Actually it is possible that pre-ringing interaction between your cell phone and the cell towers are responsible for your cell transmitting at a frequency and intensity that triggers the circuitry f the switch that belongs to the paper shredder activation circuit. For instance if the switch is based on a light sensor then the radio frequency may cause the light sensor circuitry in the shredder to activate as if the light beam were interrupted. In some cases all it take is for the signal traveling to the sensor sent by the light beam to deviate from phase or frequency to activate the circuit. 71.100.7.164 (talk) 03:29, 15 November 2009 (UTC)

It could be electromagnetic inductance from the cell phone triggering the circuit on the shredder which detects the introduction of paper to be shredded. Or perhaps the house is built over an old Indian (Native American) burial ground, and poltergeists are at work. Edison (talk) 03:35, 15 November 2009 (UTC)

Right before a cel-phone rings there is a lot of communication going back and forth between the tower and the phone. This interferes with a lot of things. Most commonly people notice this as interference in speakers. Just like speaker wires can pick up the signal, probably there's a wire between the "paper sensor" and the chip the controls the shredder that's picking up this interference. If I had to guess, I'd say that the sensor is probably analog (Optical, perhaps?) with a very tiny voltage difference between "paper" and "no paper". APL (talk) 04:33, 15 November 2009 (UTC)

cancer

Cancer is a mutation of normal cells characterized by uncontrolled growth. If a GM corn or flax cell that produces insecticide gets cancer is it also characterized by uncontrolled growth? 71.100.7.164 (talk) 02:21, 15 November 2009 (UTC)

So you sort of answered your question by defining cancer as mutations that promote uninhibited growth. DRosenbach ^{(Talk | Contribs)} 03:11, 15 November 2009 (UTC)

Only if my understanding of what cancer is or does is correct. 71.100.7.164 (talk) 03:22, 15 November 2009 (UTC)

Plants don't exactly get cancer. Plants can get tumors, but it's not really cancer because it can't spread like it can in animals. Cecil Adams touches on this briefly here. APL (talk) 04:23, 15 November 2009 (UTC)

Your question would make a lot more sense if you began with "Cancer is a mutation of normal animal cells characterized by uncontrolled growth." By redefining a common term, you can make up any ridiculous question you like. For example, I could ask: "If radiation contamination is caused by any exposure to sunlight, are all GM crops grown outside full of radiation contamination?" -- kainaw™ 04:39, 15 November 2009 (UTC)

I don't disagree with you and you are making a reasonable point but where I live there are a lot of phosphate mines and a lot of unmined phosphate. It is ver common to see trees with so called tumors but due to their encompassing size in some cases the tumors are larger than the tree. Although they are usually adjacent to each other and a dividing line is hard to establish between adjacent tumors and they appear not to have been transported to other parts of the tree through the veins of the tree they are obviously uncontrolled growths everyone assumes to be from radon gas or a radiation based interference with genomes, even though hey might be the result of a tumor causing virus. 71.100.7.164 (talk) 08:14, 15 November 2009 (UTC)

Might they be galls? -Craig Pemberton 09:00, 15 November 2009 (UTC)

These nodules, growths, tumors are very large, the largest mass of tumors surround a thirty foot oak tree at the trunk from a foot above the ground to six feet above the ground, if memory serves me correctly. Unless galls are consistently this massive then I can't explain the number of trees effected. 71.100.2.243 (talk) 11:38, 15 November 2009 (UTC)

Could be nematodes or fungi. Fences&Windows 15:29, 15 November 2009 (UTC)

Plants can't get cancer as such because their cells cannot undergo metastasis. But they do get tumour-like growths such as crown galls caused by Agrobacterium tumefaciens. Fences&Windows 15:22, 15 November 2009 (UTC)

Metastasisless malignancies are still malignancies -- basal cell carcinoma is cancer even though it rarely metasticizes. If it would never metasticize, it would still be categorized as cancer because metastasis is just one of the many surrogate biomarkers signs, so to speak, of cancer. (pre)Cancer is diagnosed prior to metastisis based on histologic findings such as mitotic figures, metaplasia/dysplasia, epithelial invasion of the lamina propria, etc. DRosenbach ^{(Talk | Contribs)} 15:41, 15 November 2009 (UTC)

Why do plants get tumors from infection by other organisms only? 68.193.225.106 (talk) 16:06, 15 November 2009 (UTC)

Evolutionary advanage of nervousness?

It seems that nervousness would be a severe detriment to survival, due to making tasks which are important to survival more difficult to perform successfully. Yet somehow nervousness hasn't been eliminated by natural selection. What survival benefit does nervousness provide that has caused this? --75.39.194.221 (talk) 02:23, 15 November 2009 (UTC)

This emotion is supposed to stop the animal from doing something risky, such as showing itself in front of a predator, eating a strange new substance, driving too fast, straying too close to a cliff edge, or jumping from it. Graeme Bartlett (talk) 02:35, 15 November 2009 (UTC)

Nervousness is supposed to stop you doing whatever it is, that is the point. What important things were there for proto-humans (or earlier animals) to do that would make them nervous? I can't think of any. Anything that would make them nervous would be something that they shouldn't do. Eg. you see a big lion sleeping next to the tree you want to pick fruit from you don't overcome your nerves and creep up to the tree, you go and get your dinner somewhere else. --Tango (talk) 02:56, 15 November 2009 (UTC)

I suppose the opposite of "nervousness" would be fearlessness. "The lion is sleeping next to the tree with the fruit I want to eat. I will climb up on the sleeping lion to reach the fruit. If the lion wakes up, I will simply spit in his eye." Very brave, but the individual might not survive to pass on his genes to the next generation. Edison (talk) 03:32, 15 November 2009 (UTC)

Emotions are complex. Nervous is a general term covering many emotional states. As you point out, nervousness can be detrimental. I don't think evolution is the best place to look for evaluating nervousness. Emotions may not leave traces as easily understood over the periods of time involved in human evolution. We may not really be able to know what advantage or disadvantage various emotional states, among them the many types of nervousness, have played at the various stages in the role of human survival over the periods of time in question. Bus stop (talk) 03:35, 15 November 2009 (UTC)

Like most behaviours, nervousness can be dysfunctional in some cases, but in others there would be a survival benefit to having second thoughts, being overly cautious, or even being visibly nervous which could alert other group members or even lead to a better-qualified member taking action. Also you're only likely to overcome nervousness if you judge that the action truly is important, so it screens out casual risk-taking. Peter Grey (talk) 03:53, 15 November 2009 (UTC)

I find that nervousness is usually quite justified. What's the point of embroidering your quilt if you have the notion that a sabretooth tiger is nearby? Vranak (talk) 04:19, 15 November 2009 (UTC)

That's right, put down the quilt, grab your spear, and get yourself a nice sabertoothed fur, instead. Much warmer than a quilt. StuRat (talk) 05:12, 15 November 2009 (UTC)

I've noticed a huge difference in the skittishness of flying insects. If they are sitting on a wall when I enter a room, some will start flying and taking evasive action immediately, while others will let you walk right up and grab them. I have more trouble understanding the latter behavior. I'd expect them to give their camouflage a chance to work, but, at some point, I'd also expect them to realize I've spotted them and flee (or flea, as the case may be). StuRat (talk) 05:17, 15 November 2009 (UTC)

Maybe they were asleep. --Tango (talk) 06:15, 15 November 2009 (UTC)

And they might not be intelligent enough to cope with the unusual environment (big homogeneous wall painted with only one color) --131.188.3.21 (talk) 10:36, 15 November 2009 (UTC)

Pure conjecture here, but the presence of individuals with crippling nervousness or brash bravery in a population might be understandable in terms of heterozygote advantage and balanced polymorphism. -Craig Pemberton 08:57, 15 November 2009 (UTC)

It could be, but I think it is more likely explained by nurture rather than nature. Crippling nervousness usually has an identifiable cause (yelling at your children over minor things a lot tends to make them generally nervous, for example). I think brashness is usually caused by over-estimating ones own abilities rather than bravery - that, and being drunk. --Tango (talk) 09:06, 15 November 2009 (UTC)

Fear and Risk aversion might help, and see The psychology of risk taking behavior. Nervousness isn't per se a pathology, the balance of whether to take risks or not - which is really what underlies nervousness - is something that affects most animals. Work in animal behaviour and ecology often talks about 'neophobia', which is a version of nervousness. "What important things were there for proto-humans (or earlier animals) to do that would make them nervous? I can't think of any." New sources or types of food, crossing rivers, climbing trees, extra-partner mating, predators or other groups of hominids nearby, etc. Fences&Windows 15:13, 15 November 2009 (UTC)

How long will lunar water last?

Scientists have recently confirmed the presence of large amounts of water on the moon. Has anyone done any work estimating how long that water is likely to last if we start using it? Are we likely to hit peak water on the moon at some point? I know we don't have any idea precisely how much water there is on the moon and we don't know how much water we are likely to want to use in the future, but does anyone have a rough order of magnitude? Is there enough for a few decades? A few millennia? Millions of years? --Tango (talk) 04:46, 15 November 2009 (UTC)

I believe you are viewing lunar water as a pure consumable, not a recyclable resource. There is no reason to assume that the water harvested from the Moon won't be recycled over and over as long as it is needed. The issue, from my point of view, is not if we will use it all up. The issue is how many people can the water on the Moon support? -- kainaw™ 04:51, 15 November 2009 (UTC)

If just small amounts are used to replace losses in life support systems, that might be the case (but it probably wouldn't - the lunar bases will almost certainly be in illuminated parts of the moon, at least partially, and water that escapes there would be heated up to sufficient degree to escape the moon's gravity). If large amounts are used to make rocket fuel (which is one of the common proposals) it certainly isn't. --Tango (talk) 06:14, 15 November 2009 (UTC)

Water on Earth is not likely to leave the hydrosphere, but water on the Moon could escape if exposed to the vacuum, so it would be in part non-renewable, with a little replacement by comet impacts. Of course, right now none of it is being used. Peter Grey (talk) 05:29, 15 November 2009 (UTC)

They blasted a 60-100 ft crater with their impactor, equivalent to a volume of 100 thousand to 1 millions gallons of disturbed regolith. As a result approximately 25 gallons of water was kicked up into space in a way the satellite could detect. So we can set a lower limit on the concentration of ice in this permanently dark crater at 25 parts per million by volume (but possibly quite a bit higher). That's not a high concentration, but on the other hand, it would suggest one could get ~100-300 tonnes of water per km² in craters such as this. The space shuttle external launch tank carries about 700 tonnes of fuel for comparison. So, the dream of using water for fuel would seem possible, but not very easy since very large areas may need to be mined. Dragons flight (talk) 10:51, 15 November 2009 (UTC)

Copepod parasite?

Anterior bit of the copepod.

Higher magnification.

I found this copepod with an egg sac today. There is some sort of tubular structure in the egg sac. My first guess was that this was how they attached their eggs, but I don't see a similar structure in photos of other egg sacs. Could it be a parasite? Or maybe someone got stuck in egg adhesive and is unwittingly along for the ride? -Craig Pemberton 08:46, 15 November 2009 (UTC)

How do paramedics repair severed arteries?

When a paramedic, combat medic, or some other first response health provider encounters a person with a severed artery (or vein I suppose) that needs treatment right away (i.e cannot wait for transportation to a hospital), what do they typically do to treat the person? Do paramedics carry an "artery repair kit"? Also, how is an artery repaired and is there any difference between how a first response surgeon with limited equipment and a someone in a hospital with the full breadth of equipment would go about reconnecting an artery? I tried looking for information and some websites mentioned stitches and grafts, but I don't think I got an accurate picture of how the severed ends are actually stuck back together. 96.253.247.216 (talk) 10:04, 15 November 2009 (UTC)

They won't repair the artery. They will stop the bleeding through a combination of direct pressure, elevation, pressure points and, as a last resort, a tourniquet. The artery will be repaired by a surgeon once they get to hospital. --Tango (talk) 10:12, 15 November 2009 (UTC)

Regarding the second half of your question, the most commonly-used technique for repairing an artery was described by Alexis Carrel in 1902 (Lyon Med 1902; 98:859–863, too early to appear in Pubmed) and illustrated here. The arterial wall is fragile and all three layers (intima, media, adventitia from inner to outer) must be rejoined in the repair, because separation and retraction of one or more of these layers, i.e. delamination, is common with severed arteries. This is made even more difficult because direct clamping or grasping with forceps can damage the arterial wall and 'kill' it (it is living tissue, after all). Thus, arterial repair is a fairly demanding task - not saying it couldn't be done in the field, but it would be a serious challenge. -- Scray (talk) 15:52, 15 November 2009 (UTC)

Thanks very much for the answers! 96.253.247.216 (talk) 22:25, 15 November 2009 (UTC)

How to apply a pressure dressing 75.41.110.200 (talk) 23:14, 15 November 2009 (UTC)

Psychology

Hi, I know a person who is always very calm and it seems like nothing can surprise her.She never shows any emotions. If something strange or incredible happens, she just says "Oh." or smth like this. (Like Robin from Robin (TV series) if you know it...) Once I've heard of alexithymia but I'm not sure she has it because she can recognize other people's feelings very well. She is quite lonely and doesn't talk much to other people because she talks very silently and no one hears her. She really can't express herself and I feel sorry for her. Any ideas which illness could this be? —Preceding unsigned comment added by Atacamadesert12 (talk • contribs) 10:53, 15 November 2009 (UTC)

I afraid we can't make diagnoses here. You will need to consult a professional. --Tango (talk) 11:02, 15 November 2009 (UTC)

Template:RD medadvice This removal is discussed here -- Scray (talk) 16:02, 15 November 2009 (UTC)

Queen Ant

I have a queen ant and she has laid some eggs. When the eggs hatch what will the little worker ants need to be fed? I know in nature they'd eat dead files or stuff, but in captivity what can I give them? —Preceding unsigned comment added by 82.43.89.85 (talk) 23:39, 13 November 2009 (UTC)

Do you know the species ? I suppose, if you don't, you can leave them a bit of everything, from leaves to fruit to meat, and they can take what they want. Leave small enough quantities so you can tell what they take. Also leave water. StuRat (talk) 13:33, 15 November 2009 (UTC)

bipolar disorder

i am repeating this question as i didn't get relevant answer. i would like to know percentage of global people affected by bipolar disorder and age wise distribution of this disorder globally ... pl help some one .. —Preceding unsigned comment added by Arun vvv (talk • contribs) 12:33, 15 November 2009 (UTC)

You might find some figures in some countries for the number (and ages) of diagnosed cases, but I don't think anyone has attempted the difficult task of guessing the rate of occurrence or age distribution world-wide. The condition is not easy to diagnose in an individual, so it is even more difficult to estimate global figures. Is it even recognised as a disorder in some countries? I assume that you have read our article linked in answer to your previous question. It suggests that about 1% of children and 2% of the population from teenage upwards suffer from the clinical condition, with perhaps a further 2% or more having a minor form. The condition is never considered to be "cured", so an age distribution is not appropriate. Dbfirs 13:16, 15 November 2009 (UTC)

PMID 17162652 is probably the best source of up-to-date information, if you have access to it. Looie496 (talk) 17:30, 15 November 2009 (UTC)

Feeling in eyes.

Do your eyes feel heat? I assume they do but I don't think I've ever though 'man my eyes feel cold' so I'm unsure. —Preceding unsigned comment added by Jimothyjim (talk • contribs) 13:22, 15 November 2009 (UTC)

It's not your eyes, but sensory neuron on your cornea -it respond to heat and so it should also respond to loss of heat. Meaning that I guess that a hit of liquid oxygen would heart (P.S. it's not the best example as such hit would also cause to extensive damage-but there is such thing as cold pain) .--Gilisa (talk) 13:41, 15 November 2009 (UTC)

Thermoception isn't a very well developed article, but it notes correctly that hot and cold thermoreceptors in mammals are in the skin. However, some animals do have thermoreceptors in their eyes, e.g. cats have cold receptors.[20] There's evidence that humans can detect cold on the cornea and conjunctiva.[21][22] Fences&Windows 14:38, 15 November 2009 (UTC)

You've never felt cold in your eyes? I have....is that unusual? Vimescarrot (talk) 15:13, 15 November 2009 (UTC)

I'd say that most people would reflexively shut their eyelids, thus reducing the stimulus that would kick ofs a response -- sort of like people who experience less tooth pain to cold air when they shut their mouth. DRosenbach ^{(Talk | Contribs)} 15:35, 15 November 2009 (UTC)

Try the opposite - if you sit close to a fire in a fireplace, you'll get a hot headache, and can often feel the heat "behind" your eyeballs (as implied above). ~ Amory (u • t • c) 19:41, 15 November 2009 (UTC)

Certainly cold water feels cold, I think. 68.193.225.106 (talk) 15:59, 15 November 2009 (UTC)

Hmm, maybe my eyes do feel cold but I just don't notice.

Looking for the name of a knot similar to the clove hitch

I'm looking for the name of a hitch knot, which is similar to the clove hitch. In the clove hitch, a part of the rope runs diagonally, compressing other parts of the rope forming the knot. In the knot I'm talking about, there's a twist in the part of the knot under the "diagonal" section. Supposedly the knot is more secure that the clove hitch. Does anyone know the name of the knot? (Sorry if my description is not very clear.) —Preceding unsigned comment added by 173.49.12.245 (talk) 15:43, 15 November 2009 (UTC)

The constrictor knot, ground-line hitch and snuggle hitch are all similar to the clove hitch, but more secure. Are you thinking of one of those? Red Act (talk) 16:33, 15 November 2009 (UTC)

The constrictor knot was what I had in mind. Thanks. --173.49.12.245 (talk) 16:49, 15 November 2009 (UTC)

activity vs sleep on mountains

i'm not asking for medical advice here, i have no intention of climbing a mountain but i'm wondering if it's true that you need to stay awake on mountains to keep your body temperature up? i'm pretty sure that sleeping well in a safe place is just as important to get your energy back up? —Preceding unsigned comment added by 87.114.162.77 (talk) 16:22, 15 November 2009 (UTC)

If you're severely hypothermic (so cold that you've stopped shivering), then falling asleep would be bad, but at that point you'd be on the verge of dying anyway. Body temperature drops a little bit during sleep automatically, but if it drops enough to be harmful, you will start shivering and that's sure to wake you up. In my experience (never been actually hypothermic), it's impossible to fall asleep if you're shivering. I have spent a few very unpleasant nights on mountains that way. Looie496 (talk) 18:29, 15 November 2009 (UTC)

If you're in a place dangerous enough that you shouldn't sleep to avoid dying, you are already very hypothermic and in danger and should calmly and carefully get off the mountain. The first step is to always avoid a dangerous situation like that by planning ahead and being safe. You will not think clearly when severely hypothermic. You should only ever go up a mountain if you have adequate shelter and warm clothing, in which case it will often be okay to sleep. ~ Amory (u • t • c) 19:38, 15 November 2009 (UTC)

I agree with what has already been said. On a related note, however, at very high altitude (eg. Everest Camp IV) sleep apparently becomes very difficult. It's not that it is dangerous to sleep, it's just difficult to get to sleep. --Tango (talk) 21:56, 15 November 2009 (UTC)

Ah ok, maybe i misunderstood what i was told then. Stay awake if you're about to die, nice lol! Tx for hypothermia link, that explains a lot. —Preceding unsigned comment added by 87.114.162.77 (talk) 23:50, 15 November 2009 (UTC) --87.114.162.77 (talk) 23:52, 15 November 2009 (UTC)

self-serve check-outs and phone answering systems

Most of these registers are manned by one cashier to four registers. In many cases this cashier is busy with another customer when a problem happens. For this reason many people are exposed to a talking register that treats them as if they were a computer. An even worse situation of computers treating people like they were computers are telephone, bank and other business and institutional phone answering systems (USPS is one of the worst). Are such systems a threat to the civility of mankind and perhaps in part responsible for indiscriminate psycho crimes like terrorism? 71.100.2.243 (talk) 16:37, 15 November 2009 (UTC)

I don't think this is a very scientific question, and I don't have a very scientific answer. These computers you speak of do not pass the Turing test, so people can consistently tell the difference between talking to a human and dealing with one of these computers; thus, I don't think any confusion between the two contributes to violent behavior. My sense is that if people relax and focus on the task at hand, the task gets done. -- Scray (talk) 16:47, 15 November 2009 (UTC)

"Are such systems a threat to the civility of mankind and perhaps in part responsible for indiscriminate psycho crimes like terrorism?" I don't think there's any evidence that such things contribute to threats against the "civility of mankind" (whatever that means), and have seen zero evidence that such systems have any responsibility for "indiscriminate psycho crimes like terrorism". I think it would be fairly idiotic to assume without any evidence that frustration with phone answering systems has any connection to terrorism. The systems probably do contribute to a decreasing satisfaction amongst consumers with customer service (I cannot stand the phone systems and find them unhelpful; if you keep pressing the zero key, you often end up with a live person, though), but and they do have economic effects (they are used to avoid hiring live human beings), but other than that, I don't see any reason whatsoever to ascribe them much influence. --Mr.98 (talk) 17:04, 15 November 2009 (UTC)

I actually prefer the self-checkout, for these reasons:

1) I can check each price and make sure it's correct. You can try this in a traditional check-out, but the display is often aimed at the cashier, not you, and the cashier may check things so quickly that you can't keep up. In almost every load of groceries, I'm overcharged on at least one item, so missing this is expensive.

2) I can bag things properly. I put the frozen items together, the refrigerated items together, etc., while many baggers don't bother.

3) I can avoid have my food damaged by the cashier and bagger. I've had bananas slammed down, only to get bruises almost immediately, and have had a greeting card placed in the leaking milk sludge on the conveyor belt, even after I handed it directly to the cashier.

That said, they really need to work on a few problems:

A) They don't assign enough people to oversee them. Perhaps one cashier for every 2 or 3 would work. However, they need to actually keep the cashiers present. They frequently seem to walk away to do God-knows what, leaving the customers totally unattended. Maybe they can put a location sensor on the cashiers and dock them pay for every minute they are out of the area ? (Or fire them if they take it off.) There has to be some way to get them to do their jobs.

B) Many tasks require a cashier that shouldn't. If I have a coupon, I have to hand it to a cashier. If I want to cancel an item I scanned, I need a cashier. If I have an item with a hand-marked price, I need a cashier (in this case they need to stop hand-marking prices).

C) Many of the automatic check-out lanes need repair. There's some where the scale doesn't work, some where the voice part is broken, etc. They continue to use these defective lanes, which cause even more time demands on the cashiers. StuRat (talk) 18:45, 15 November 2009 (UTC)

With all of your points I agree. I usually buy canned goods in bulk and people behind me in line get perturbed whenever I start scanning individual cans. One cashier refused to override and enter the number of cans saying it was against chain policy. In another instance when my card was not approved due to faulty communication link the cashier refused to return my card until I threatened to call the police and have him charged with theft. My bank backed up my contention and he would have gone to jail. The problem I experience most is that recently there is some kind of holdup every time I use the self-checkout register. Repeatedly pressing zero usually results in the phone system hanging up.

I can't seem to find an alternate system or solution. Perhaps I can find a store that will allow me to fax, email or call ahead to place an order and have it ready for me to pick up in a couple of hours. 71.100.2.243 (talk) 20:30, 15 November 2009 (UTC)

As for the dehumanizing effects, the monotone voice is high among them, especially when it says something like "Have a good day". It just doesn't work when it comes from a machine. With a cashier you may suspect that they don't mean it, but at least it's possible that they do. And a monotone voice repeating the same thing ad infinitum actually seems even worse for the people who work there; I've seen them go to extremes to shut it up. StuRat (talk) 21:02, 15 November 2009 (UTC)

Do other people get "Unexpected item in the bagging area" every time they place an item in their bag, or is it just me? Certainly contributes to the stress level. Itsmejudith (talk) 21:19, 15 November 2009 (UTC)

I have had that problem at one particular chain of home improvement stores, but it's now been resolved. I think this reflects an important aspect of these systems - they will improve when people complain and companies listen, and the improvements scale well (compared to human training, for example). While I like to see people employed, there are some tasks that are so mindless and repetitive that machines can do the job better. Scanning groceries seems like one of those. -- Scray (talk) 21:26, 15 November 2009 (UTC)

In the case of self-check outs, a human still does the scanning, it's just now the customer. StuRat (talk) 21:53, 15 November 2009 (UTC)

Point taken - thanks for setting me straight there. I do anticipate greater automation being the next step, probably eliminating checkout aisles as we currently recognize them, but I don't want to treat the RD as a forum. -- Scray (talk) 22:30, 15 November 2009 (UTC)

Do you mean like the Quick Check system used in Waitrose? That is awesome, and does pretty much eliminate the normal checkout for everything except random rescans. And it alerts you to special offers when you scan things in, which is surprisingly useful. Doesn't quite cancel the greater expense of shopping at Waitrose, though. I can see it catching on in a lot of other shops if the initial cost comes down: remember how quickly the self-service checkouts caught on? 86.142.231.220 (talk) 23:43, 15 November 2009 (UTC)

I think he means more like the self scan checkouts at ASDA and Tesco.  Ronhjones  ^(Talk) 00:23, 16 November 2009 (UTC)

In the case of telephone companies who have perfected the technology to the greatest extent the monotone is almost gone but the resistance to turning the call over to a human operator even greater. (same for USPS who use this technology). To speak with an operator versus the system hanging up you first must provide your telephone number or account number, if its about data versus voice and if its data what your operating system is, what type of modem you have and on and on and on. An even more expensive lunch for the added speaking capability with even greater resistance to putting you in contact with a real live human including substantial wait time and failure to allow contact if your particular issue is not in its list. Try to get in touch with the right party to report a tree that is now so large it hs grown three inches around the cable or to report a thousand other problems. The menus are never well developed or based on proper classification principals. (see http://academia.wikia.com/wiki/Optimal_Classification) 71.100.7.189 (talk) 23:40, 15 November 2009 (UTC)

Rechargeable battery

How does the total life of a rechargeable battery compare with a non-rechargeable ? By "total life", I mean all the milliAmp hours you can get out of either battery until it's voltage drops permanently below the rating. In particular, I'm interested in AAA batteries, so I can decide whether rechargeables make sense in my walky talky. The rechargeables in question are Ni-MH and the non-rechargeables are "super heavy duty", which I think means "not alkaline". StuRat (talk) 18:06, 15 November 2009 (UTC)

I don't know about AAA batteries, but I did find this piece on how rechargeable vs. non-rechargeable AA batteries work for long term use in electronics. It recommends that for devices that are used often or "draw bursts of power" (such as a digital camera for taking a picture with flash), use rechargeables, and for seldom used or low power devices, such as flashlights or remote controls, use single-use batteries. Ks0stm ^(T•C•G) 18:49, 15 November 2009 (UTC)

The issue is that my price structure may well be different than theirs, since I can get permanent AAA cells in an 8-pack for a dollar, while I have to pay 20 times as much for rechargeables. So then, the question is if the rechargeables last 20 times longer. StuRat (talk) 18:57, 15 November 2009 (UTC)

Permanent AAAs aren't - that would be great ;-). The answer to your question depends not only on the battery type, but also on the application. Most rechargeables provide a fairly constant voltage (and current) until they are fairly drained, and then drop quickly towards (nearly) zero. Conventional batteries drop more evenly. If your walky talky is digital, it will need a certain minimum voltage, and you may not be able to use plain batteries to their full capacity. Also, most rechargeables can be used a lot more often than 20 times. As far as I can tell, for all items that use significant current and are in frequent use, rechargeables are the more economic choice. On the down side, they have a much quicker self-discharge rate, so they are unsuitable for storage or items like an alarm clock, that runs for years on a plain battery. ---Stephan Schulz (talk) 20:48, 15 November 2009 (UTC)

You seem to have assumed that both types of battery last just as long on the initial charge. I don't agree. I think rechargeables discharge faster, especially when old, but I don't know by how much. StuRat (talk) 21:06, 15 November 2009 (UTC)

No, I did not assume such. Yes, older rechargeables eventually loose capacity. As for initial capacity, look at List of battery sizes, which indicates non-rechargeables have between 50% and 20% higher initial rated capacity. But, since rechargeables hold voltage longer, they will discharge faster over the same resistance than non-rechargeables. Of course, they will typically also give higher performance. Anyways, due to the fact that they have much more than 20 recharge cycles, my point stands. --Stephan Schulz (talk) 22:05, 15 November 2009 (UTC)

Human Scent

I had asked a previous question about human scent, but didn't find the answer to one part: Why can people not smell their own scent? Is there any way to make this possible? Thanks in advance... Ks0stm ^(T•C•G) 18:39, 15 November 2009 (UTC)

I suppose if anybody was in any way 'cut off' from their own scent, either by intensively using deodorant or perfume or by some mechanical means (i. e. carrying a clothes pin on your nose for a year, or any other nasty way), then I suppose after the foreign means had been removed one could become conscious of their own smell. IMHO. --Ouro (blah blah) 18:48, 15 November 2009 (UTC)

I think people can. You may get accustomed to any smell you are exposed to continuously, though, so may need a higher concentration to detect it. So, if you run a marathon and sniff your pits, I bet you will smell something. StuRat (talk) 18:51, 15 November 2009 (UTC)

It's called habituation, but when one raise his hand to enjoy the wonderful aroma of his armpit, just after intensive training in a gym, then he can smell himself very well. But if you leave him in a room filled with this odor for one-two hours, it would be more than enough to make it imperceivable. The first to describe the molecular mechanism for it (in Aplysia) was Eric Kandel and along with other studies he performed, his studies on the Aplysia's habituation mechanism actually founded the modern study of memory processes. Much more interesting thing happen when people try to tickle themselves, here-in different from habituation, the brain 'predicts' the action and it knows what areas exactly are going to be tickled, so it won't have any effect.--Gilisa (talk) 19:51, 15 November 2009 (UTC)

a purely conceptual thought experiment

In a purely conceptual thought experiment I have discovered the CONTIUM.

The CONTIUM is simply a neutron, which instead of becoming a proton and electron or Hydrogen-1 becomes a CONTRON and a positron (a positively charged electron ).

The significance of this discovery is that external energy is no longer required to overcome the Coulomb barrier. In fact there is no Coulomb barrier.

The only way to keep Protium and Contium apart is with a polar magnetic field strong enough to do the job. When the field collapses the Protium and Contium are attracted.

My question is do they annihilate each other or do they undergo fusion and if fusion what are the most likely byproducts? 71.100.2.243 (talk) 19:22, 15 November 2009 (UTC)

Anything could happen since it's particles that dosn't exist in reality, but you may want to define their anti-particles and invoke CPT symmetry to run the reactions in reverse. It's a common line of reasoning in particle physics. EverGreg (talk) 19:29, 15 November 2009 (UTC)

Type 1 Diabeetes - Sugar allowed in a can of drink

Really obscure question here, but does anyone know how muc h sugar people with Type 1 diabetees are 'allowed' to have in a can of drink? It's kind of a weird question but I'm asking for a friend :S —Preceding unsigned comment added by 82.11.245.145 (talk) 19:35, 15 November 2009 (UTC)

There is no such allowance. The source of the sugar is largely irrelevant. The amount of sugar they can have will depend on the nature of their condition (everyone is slightly different) and how much insulin they have had/will have. --Tango (talk) 19:45, 15 November 2009 (UTC)

Okay well, let me rephrase, roughly how many grams of sugar do you reckon an average type 1 diabeetes person could have in a drink without it affecting their sugar level? 82.11.245.145 (talk) 19:54, 15 November 2009 (UTC)

This is massively getting into the realm of medical advice, which we aren't allowed to give here. Suffice it to say that even for an "average" type-1 diabetic, if there was such a thing, the amount of sugar they could safely drink in a can would depend on a huge number of factors and there's no number we could give you that would be particularly meaningful without detailed knowledge of the specific situation. ~ mazca ^talk 20:13, 15 November 2009 (UTC)

This is purely hypothetical, nobodys drinking any cans of coke based on the advice here :P Also I don't mean safely, I mean literally no change in their levels, not even a safe change, just no change. Jimothyjim (talk) 20:22, 15 November 2009 (UTC)

None at all, then. Any consumption of sugar will raise blood sugar levels temporarily, in a diabetic or otherwise. --Tango (talk) 21:02, 15 November 2009 (UTC)

Okay, thanks all, I think everythings all sorted out now. More confusion over the question than anything. Jimothyjim (talk) 21:08, 15 November 2009 (UTC)

Toxicity of hydrogen peroxide

In Charlie Chaplin's film Monsieur Verdoux, Chaplin's character thinks he's pouring poison disguised as hydrogen peroxide into a bottle of red wine, but instead, he's pouring real hydrogen peroxide into the wine. He and his lady friend later drink the wine, and suffer no ill effects, save for inebriation. Is hydrogen peroxide actually toxic? Does it have any harmful effects when ingested in such small quantities (only a few centilitres)? JIP | Talk 20:27, 15 November 2009 (UTC)

One of the uses of the common 3% hydrogen peroxide solution is as a gargle, so presumably it's not very toxic. 100% hydrogen peroxide would burn you severly, on the other hand. StuRat (talk) 20:45, 15 November 2009 (UTC)

A 100% solution is hard to get and even harder to store for a long time. The most important thing is the concentration 3% or 30%. Wine has some imputities which will slowly oxidize and the hydrogen peroxide vanishes away. The small particles will also catalyze the decomposition of hydrogen peroxide. --Stone (talk) 20:51, 15 November 2009 (UTC)

Heteroaromatic Chemistry Problem

I can see from experimental results that the chlorine in 2-chloropyridine is easily displaced by nucleophiles such as amines. However, this isn't the case with 3-chloropyridine....why?! 188.221.55.165 (talk) 22:44, 15 November 2009 (UTC)

discoloration in schitzu's hair

This question has been removed. Per the reference desk guidelines, the reference desk is not an appropriate place to request medical, legal or other professional advice, including any kind of medical diagnosis, prognosis, or treatment recommendations. For such advice, please see a qualified professional. If you don't believe this is such a request, please explain what you meant to ask, either here or on the Reference Desk's talk page.

This question has been removed. Per the reference desk guidelines, the reference desk is not an appropriate place to request medical, legal or other professional advice, including any kind of medical diagnosis or prognosis, or treatment recommendations. For such advice, please see a qualified professional. If you don't believe this is such a request, please explain what you meant to ask, either here or on the Reference Desk's talk page. --~~~~

) 188.221.55.165 (talk) 23:49, 15 November 2009 (UTC)

November 16

Centrifugal force

I'm doing a lab report on ficticious forces, and something doesn't seem to make sense. The design of the experiment is as follows: a stationary channel has a ball roll slowly through it, while the channel is overtop some paper on a rotating platform. Again, the ball is NOT rotating (just going in a straight line), but it's making contact with the paper that it rotating, and every 30 ms or so the ball makes a mark on the paper, so that's its trajectory is traced out. Now according to the lab manual (and in agreement with the results we obtained), the ball will slow down as it approaches the centre, and speed up while it's leaving, and apparently this is due to centrifugal forces.

Now to me, this doesn't make much sense. The ball itself shouldn't be experiencing any forces (ignoring friction), and even in the reference frame of the rotating paper, the ficticious force acting on it should be directed towards the centre, allowing it to continue in a circular path. After all, if the ball wasn't moving at all, it wouldn't start moving away from the centre, so I have trouble believing that there would be a ficticious force acting on it. But I wasn't actually there for the lab; is it possible that it was the ball that was rotating while the paper was stationary, and that my lab partner is just an idiot?

Stone artifact need help with what it is...

I need help with a stone that my daughter found on Myrtle Beach S.C. It is very old  and it is either indian or maybe even from the stone age. We have pictures and would appreciate any help with whom  we could email  for assistance. Thank you for your time