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July 11

aerospace

how to be an aerospace engineer ???? — Preceding unsigned comment added by Sourabh007sak (talk • contribs) 03:13, 11 July 2011 (UTC)

Go to college/university, and study aerospace engineering, which is a subdiscipline of mechanical engineering. --Jayron32 03:15, 11 July 2011 (UTC)

Be sure to heavily emphasize the study of computers, electronics, and software, which are now a significant component of modern aerospace design. Also heavily emphasize the pure sciences, such as physics, chemistry, and mathematics. Aerospace engineering is very broad, so investigate some of its subdisciplines: fluid dynamics; material science; propulsion engineering; control theory; and of course the more broad topics that apply to large engineering projects, such as optimization and operations research. Nimur (talk) 18:35, 11 July 2011 (UTC)

Start by making paper airplanes. StuRat (talk) 17:25, 11 July 2011 (UTC)

Be financially prepared to be laid off when the aerospace project is finished. I recall reading about a former aerospace engineer laid off when the Apollo program was done. He was one of the world's experts on electrostatic.electromagnetic shielding of spacecraft, and the only job he could find was driving a cab. NASA just cycled down from 5000 to 1000 employees at Cape Canaveral. Edison (talk) 19:33, 11 July 2011 (UTC)

A lot of people with an aerospace engineering degree work in a job which is more general engineering. I don't think that fellow would have needed to drive a cab if he would have asked Caterpillar or DuPont if they were interested in a engineer (not specifically a spacecraft static specialist position). Googlemeister (talk) 20:50, 11 July 2011 (UTC)

The Cambrian explosion

Hello.

I've noticed that a lot of scientific papers of the late 1980s and early 1990s spoke of "dozens" of extinct animal phyla that originated during the Cambrian explosion and have since become extinct. On the other hand, recent scientific literature has declared [almost] all of these phyla to be invalid and has reclassified their members into extant phyla.

I would like to know whether this shift in thinking is the consequence of new palaeontological data becoming available, or it is merely an attempt by scientists to make the phylogeny of the Cambrian fauna appear simpler than it really was.

Is the reclassification of members of these "extinct" phyla into extant phyla supported by the data available in the fossil record? If so, what data has become available since the early 1990s? Thank you very much. Leptictidium (mt) 06:03, 11 July 2011 (UTC)

It sounds like you are doubting the integrity of the scientists that did the more recent classifications. Do you have any reason for that? Dauto (talk) 08:52, 11 July 2011 (UTC)

I think the major differences are that cladistics has, more-or-less, taken over, and that we can now use anatomical, genetic and protein markers to figure out phylogenetic trees to get a much better understanding of the tree of life as a whole. Also, we have additional fossil finds that connect different animals and groupings - see e.g. the story of Anomalocaris, which turned from 3 animals into one. --Stephan Schulz (talk) 09:59, 11 July 2011 (UTC)

A large part of what we know about the Cambrian explosion has come from studying the fossils of the Burgess Shale. One of the proponents of the "many phyla" interpretation was Stephen Jay Gould, whose book Wonderful Life summarises the early Burgess Shale research. An alternative and more "conservative" interpretation, based around convergent evolution, has been championed by Simon Conway Morris. The whole area is the subject of ongoing research. Gandalf61 (talk) 10:07, 11 July 2011 (UTC)

Are there any specific reasons the "many phyla" interpretation has lost favour in the last couple of decades? Leptictidium (mt) 10:56, 11 July 2011 (UTC)

I'm not very familiar with the Cambrian explosion fauna, but it could simply be that Stephen Jay Gould's death has removed the most vocal proponent of the hypothesis. Gould literally wrote the book popularizing the Burgess Shale fauna and was also a supporter of what he called "bushiness" of taxonomic families (see Full House for more). Matt Deres (talk) 16:06, 11 July 2011 (UTC)

I'm not convinced that Gould, while extraordinary in popularizing his ideas, was as solid with science. I don't want to say "mountain out of a molehill," but that phrase came to mind. Imagine Reason (talk) 00:02, 13 July 2011 (UTC)

It is important to realize that all of our commonly used classification levels (kingdom, phylum, class, etc) are basically artificial. Evolution shows us tree structures with hundreds of branch points if not more -- picking out one particular branch point and calling it the "phylum" level is rather arbitrary. There is tremendous dispute nowadays about the best way to do that. Even when the evolutionary history of a species is well understood (which is often not the case), it may be quite difficult to map it onto the very limited set of levels that Linnaeus defined. Looie496 (talk) 22:03, 11 July 2011 (UTC)

As we get more details from fossils, the most likely classifications by lineage change. 99.24.223.58 (talk) 23:48, 11 July 2011 (UTC)

Bear in mind that more and more Vendian fossils have come out, giving more reason to suspect a longer timeline. Wnt (talk) 05:31, 12 July 2011 (UTC)

Interesting! Please elaborate. 99.24.223.58 (talk) 18:39, 13 July 2011 (UTC)

Swimming in Jello

I remember a that some university in the Midwest (maybe Minnesota) conducted a study where they compared swimming in water versus various viscous liquids. I think they found that the speeds where the same. Does anyone know the study that I am talking about? I have a reference question (talk) 11:10, 11 July 2011 (UTC)

http://www.nature.com/news/2004/040920/full/news040920-2.html --Sean 13:42, 11 July 2011 (UTC)

Mythbusters also tackled the question in their Swimming in Syrup episode, and came to the same conclusion as the University of Minnesota team, i.e., that swimming in a liquid that was about the same viscosity as syrup, i.e., a bit more viscous than water, resulted in a speed that was as fast as swimming through water, within their judgement of experimental error. However, swimming in a liquid that was much more viscous than water resulted in a speed that was much (28%) slower than swimming through water. Red Act (talk) 13:56, 11 July 2011 (UTC)

I read the above with disbelief until I realised that the syrup was the less-viscous form, not the Golden syrup that immediately springs to mind for readers in the UK. Has anyone ever tried swimming in treacle? Dbfirs 11:52, 12 July 2011 (UTC)

In one sense, half of everyone swam in a liquid more viscous than water when the sperm cell used its flagellum to propel itself through the cervical mucus, a mixture of water (90%) and glycerol in the female reproductive tract. Cuddlyable3 (talk) 10:11, 13 July 2011 (UTC)

what is the palm theory？

what is the palm theory？how to use it？ — Preceding unsigned comment added by Wenwenlover07 (talk • contribs) 12:09, 11 July 2011 (UTC)

Do you mean the Palm–Khintchine theorem? Also, why do you type strange question marks? --Jayron32 12:19, 11 July 2011 (UTC)

There's nothing particularly strange about the question mark. It's just the 'fullwidth' form ([1]) which likely is the default on a Chinese-language keyboard setup, for compatibility with the wider Chinese glyphs: [2]. TenOfAllTrades(talk) 13:13, 11 July 2011 (UTC)

They certainly look strange to me, since that font apparently isn't supported on my PC. StuRat (talk) 17:22, 11 July 2011 (UTC)

There is a literature on Palm theory, but it is very esoteric mathematical stuff -- the study of so-called "Palm measures". Looie496 (talk) 21:56, 11 July 2011 (UTC)

See Point process and Chapter 13 of [3]. 99.24.223.58 (talk) 00:23, 12 July 2011 (UTC)

Breeder reactor

They apparantly make more nuclear fuel than what you put in them. My question is, where does the extra energy come from? If they truely created more fuel, wouldnt they be able to both run for ever and supply fuel for other reactors, so that no new nuclear fuel was wever needed. 92.24.187.78 (talk) 14:19, 11 July 2011 (UTC)

It's not so much that they create more energy than is contained in the starting materials; you're quite right that that would be impossible. Rather, the breeder reaction allows the conversion of stable, heavy nuclei (so-called fertile material) into fissile isotopes which can be used in a reactor. Only a small initial investment of fissile material is required as a source of neutrons to start the breeder process, after that it's theoretically possible to fuel the whole thing with the freshly-transmuted isotopes.

Make no mistake, the breeder reactor is 'consuming' those fertile isotopes; in principle their supply is finite, and eventually even a breeder reactor would run out of fuel. In practice, the fertile isotopes are enormously abundant naturally (at least compared to the naturally-occurring fissile isotopes), and readily-available supplies would last for thousands of years. TenOfAllTrades(talk) 14:43, 11 July 2011 (UTC)

To elaborate a little bit:

The nuclear reactions in a reactor are generated by the fissioning of fissile isotopes. Fissile isotopes are pretty rare in nature. Far more abundant are fertile isotopes, which, after absorbing a neutron, eventually become fissile isotopes.

So let us imagine our reactor fuel that contains 5% fissile isotopes (U-235, in this case), and 95% fertile isotopes (U-238, for example). While the fissile isotopes burn up, a large number of neutrons are generated. Some of these will deposit in the fertile isotopes, and create more fissile isotopes. In this case, U-238 absorbs a neutron and eventually, after a few days of decaying, becomes Pu-239, which is fissile.

Then we use a big chemical processing plant (see nuclear reprocessing) to extract all of the new fissile isotopes from the used ("spent") fuel, and use that to create new fuel.

As for relative abundance, consider the case of uranium, where less than 1% of all uranium in the world is U-235, and the rest is U-238. (There are other fertile isotopes as well beyond uranium-238.) Now if you could turn all of that U-238 into Pu-239, using just some of that initial less than 1% of U-235, that means you'd have nearly 100X as much nuclear fuel as there is without breeding. In reality the percentages are not necessarily that high (you lose some of the material while reprocessing, and the inside of a reactor is a complicated environment), but it's still a pretty impressive amount (the number our reprocessing article gives is +60X). You're not creating "new energy" so much as using a small amount of "start-up" energy to convert the other isotopes into forms that would be useful for producing energy. (U-238, as found in the wild, is not useful for producing energy — it needs to be put into a reactor and slightly changed before that is the case.) --Mr.98 (talk) 15:01, 11 July 2011 (UTC)

The short answer: basically any large nucleus will release energy if you break it up into smaller pieces. The problem is that most of the readily available large nuclei are types that are nearly impossible to break. A breeder reactor converts some of the hard to break nuclei into something breakable ("fissile") so that their energy can be released. Rckrone (talk) 16:54, 11 July 2011 (UTC)

I think that's a little too short and simplistic, personally... --Mr.98 (talk) 21:55, 11 July 2011 (UTC)

The OP explicitly asks where the energy came from. That question has a simple answer: As with all nuclear reactions, the energy released by a reactor comes from the nuclear binding energy of the atoms. Energy was placed in the atomic nucleus during stellar nucleosynthesis, a very long time ago. A breeder reactor is essentially converting a stable nucleus (with lots of energy that's hard to get out) into an unstable nucleus (with the same amount of energy, or even a little bit less energy, but this energy is easy to release). The energy we harness when we fission atoms in nuclear reactors is basically coming from millions of years of stored heat from stellar fusion: the ultimate fossil fuel. Extreme heat and pressure inside a sun caused small atoms to fuse into larger atoms, locking in that energy in a very stable form, embodied by the strong nuclear force. When we split the atom back apart, we're returning the energy into a useful form: thermal energy, which is used to heat water and drive a steam-turbine. Nimur (talk) 23:36, 11 July 2011 (UTC)

Er, they asked where the extra energy comes from. Which to me implies that the confusion is over fertile vs. fissile, and why you end up with more fissile material when you end than when you started. (And the rest of the question, beyond the second sentence, makes that more clear.) I don't think it's a question about the origins of binding energy in general. --Mr.98 (talk) 01:38, 12 July 2011 (UTC)

Large edible leaves ?

I'm trying a low-carb diet, part of which involves making lunch-meat sandwiches using leaves in place of bread. I've been using romaine lettuce. I'd prefer spinach, but the leaves aren't big enough. Is there a variety of spinach with bigger leaves ? Are there any other plants with large, edible leaves ? I seem to recall that stuffed grape leaves are used in Greek cuisine, but do they need to be cooked ? Do we have an article on this topic ? StuRat (talk) 17:19, 11 July 2011 (UTC)

You could try kale, it should be plenty large enough for sandwiches. 108.15.155.91 (talk) 17:36, 11 July 2011 (UTC)

Banana leaves are large and inexpensive. Incidentally, you'd be better off replacing the meat than the bread. Instead of your "lunch meat" of ground up lips, eyelids, and anuses, try tempeh or seitan, both of which are high-protein, have a pleasantly meaty texture, and can be made to taste like just about anything with any of a million different recipes you can find easily online. -- SmashTheState (talk) 18:02, 11 July 2011 (UTC)

If you don't already have a wheat gluten sensitivity, it sounds like seitan would give you one. StuRat (talk) 18:20, 11 July 2011 (UTC)

Banana leaves are large and inexpensive and inedible. --Sean 18:43, 11 July 2011 (UTC)

Yes there are plenty of different varieties of spinach, not just the unappetising stuff that comes in bags. I get different ones from my local Indian food shop. When I used to grow spinach, I used to grow Perpetual spinach which had larger leaves if you let them grow. You might also want to try and get Swiss chard or spinach beet. --TammyMoet (talk) 18:05, 11 July 2011 (UTC)

I rather like the flat-leafed spinach that comes in bags, but it's too small for this purpose. StuRat (talk) 18:21, 11 July 2011 (UTC)

Cabbage has large leaves and is often eaten raw, e.g., in cole slaw. You might also try Napa cabbage - a better shape for rolling or for making "flat" sandwiches. Or other types of Chinese cabbage.

Grape leaves are wrapped around other foods and cooked. I'm told that the big leaves are too tough to use for this purpose and the small ones are probably smaller than you want. Wanderer57 (talk) 18:42, 11 July 2011 (UTC)

Would using the concave region of one or more celery stalks count? Those are very high in fiber, so they go well with meats, and they technically have negative net calories. It might be possible to use the leafy regions of celery, which are just as edible and healthy as the stalks, for one half of a meat-celery sandwich, but appropriately cutting, forming, or deviling the meat might turn out to be more labor intensive. *goes to perform an experiment with the celery, chicken and talapia in the fridge* 99.24.223.58 (talk) 23:06, 11 July 2011 (UTC)

I actually do fill celery with peanut butter (see next question), but lunch-meat doesn't seem like a good fit. StuRat (talk) 00:26, 12 July 2011 (UTC)

Celery filled with cream cheese and paprika on top! YUM! Vespine (talk) 02:35, 12 July 2011 (UTC)

No, with cream cheese you need raisins ! StuRat (talk) 03:54, 12 July 2011 (UTC)

Filling celery with creme cheese or PB kind of defeats the point of celery though. Googlemeister (talk) 13:19, 12 July 2011 (UTC)

For a low-calorie diet, yes, but not for a low-carb diet, where proteins and fats are fine. StuRat (talk) 05:24, 13 July 2011 (UTC)

My celery was too droopy to work well with meat, so I ended up having chicken without any vegetables. I would have been far better off with brazil nut butter. I wonder how long that keeps. — Preceding unsigned comment added by 99.24.223.58 (talk) 04:06, 12 July 2011 (UTC)

Vine leaves are often used for wrapping food in middle-eastern cuisine. --Colapeninsula (talk) 10:25, 12 July 2011 (UTC)

As far as I know, all cucurbits (pumpkins, squash) throw edible foliage, and most cultivars produce huge, durable leaves. Some – especially C. pepo's – are more difficult to handle than a rosebush, but cooking should eliminate most of the spininess (although if you cooked them, you wouldn't really use them in lieu of bread on a sandwich). C. maxima leafs are big enough for three-foot subs, let alone normal sandwiches; as long as you cut out/around the primary vein, which is still a bit sharp, you're good. Juliancolton (talk) 21:01, 12 July 2011 (UTC)

Thanks for all the answers so far. I should have specified that I want leaves which can be eaten raw. StuRat (talk) 05:27, 13 July 2011 (UTC)

Making my own peanut butter

I'd like to pour peanuts (or real nuts) into a machine and have a single serving of peanut butter or nut butter come out. This is because jars of peanut butter either seem to contain unhealthy hydrogenated vegetable oil or separate into a layer of oil and a layer of concrete. I supposed I could use a blender, but that would result in peanut butter all clumped around the sharp blades. So, the machine would really need to have it's own method of ejecting the peanut butter. Is there such a device ? I'm also worried that cleaning it after each use may be too difficult, is there a way to make that easier ? StuRat (talk) 17:19, 11 July 2011 (UTC)

"Peanut butter maker". ~ Mesoderm (talk) 17:21, 11 July 2011 (UTC)

Thanks. How easy are those to clean ? StuRat (talk) 17:58, 11 July 2011 (UTC)

Also, if you don't want to buy the machine, many grocery stores (especially co-ops and places that sell good-quality bulk foods) have the machine there, and you can just take a re-usable container with you to fill up with fresh ground PB. It would still probably be cheaper to use your own machine in the long run (and you don't have to worry about what they are cleaning the machine out with at the store). ~ Mesoderm (talk) 17:24, 11 July 2011 (UTC)

That wouldn't really work for a single serving. If I get more than that, it's going to form concrete between uses. StuRat (talk) 17:58, 11 July 2011 (UTC)

I'm not sure what you mean about forming concrete between uses. I usually get about a pound or so of it at a time, and it keeps fine. ~ Mesoderm (talk) 18:17, 11 July 2011 (UTC)

Also, isn't there an emulsifier they can use in peanut butter that's healthier than hydrogenated vegetable oil ? (Our peanut butter article say that palm oil can be used, but that's also unhealthy.) StuRat (talk) 17:58, 11 July 2011 (UTC)

If you went to a health food shop, no doubt you could find organic peanut butter which would meet your criteria. --TammyMoet (talk) 18:01, 11 July 2011 (UTC)

Are you sure ? They all seem to separate. StuRat (talk) 18:02, 11 July 2011 (UTC)

I've been eating pure peanut butter for decades, and separation is perfectly normal. All you do is mix it up before you eat it. I've never had it turn into "concrete," no matter how long it's been sitting. When you mix it up, it turns back into peanut butter. The whole point of eating pure peanut butter is to eliminate the additives like emulsifier in the commercial brands (and to get rid of the aflatoxin contamination that results from mass production). -- SmashTheState (talk) 18:18, 11 July 2011 (UTC)

And get rid of the salt and the sugar. Bielle (talk) 18:36, 11 July 2011 (UTC)

please. There's nothing about aflatoxin contamination that is intrinsicly associated with mass production when it comes to food like peanut butter which come from a source (peanuts) at strong risk of contamination.

And I would actually expect organic peanut butter is a greater risk then high quality non organic peanut butter given non usage of fungacides and common poor scientific knowledge of many of those involved. (This mentions a study which found something similar although apparently not specifically on organics [4]/[5] and BTW read Andrew Weil before making any accusations of corporate shill.)

At the very least [6] choosing a reputable organic brand who test their peanut butter for aflatoxin contamination as required by the FDA in the US (e.g. [7]) and actually understand what aflatoxin is, how contamination happens and how to reduce* it; rather then some random home made brand who may not be required to test their products and probably don't and may not even be properly aware of the risk or otherwise believe silly things. *reduce is a key word, anyone who claims their peanut butter has no contamination almost definitely doesn't know what they're talking about.

Nil Einne (talk) 15:51, 12 July 2011 (UTC)

There's nothing wrong with emulsifiers like lecithin, found in egg white. Elle _{vécut heureuse} ^{à jamais} (be free) 21:59, 11 July 2011 (UTC)

And does anybody add that to peanut butter ? StuRat (talk) 23:00, 11 July 2011 (UTC)

Yes, emulsifiers are common in peanut butter, and if I remember correctly, lecithin need not be listed on the ingredients. 99.24.223.58 (talk) 00:10, 12 July 2011 (UTC)

OK then, is there a brand of PB which uses lecithin in place of hydrogenated vegetable oil, and doesn't separate ? StuRat (talk) 00:21, 12 July 2011 (UTC)

I'm not sure. Lecithin is a vegetable oil which is usually hydrolyzed, which is like being hydrogenated with enzymes instead of hydrogen. 99.24.223.58 (talk) 01:21, 12 July 2011 (UTC)

Is that as harmful as hydrogenation ? StuRat (talk) 01:49, 12 July 2011 (UTC)

Hydrolysis is not the same as hydrogenation.

To my knowledge, lecithin is not harmful, though I wouldn't swear to that. But really, you should just get over caring about the peanut butter separating. As STS said, you just mix it up again. Alternatively, keep it in the fridge (when it's not separated), and it won't separate. Once you get used to natural peanut butter, you'll never go back. --Trovatore (talk) 01:54, 12 July 2011 (UTC)

I'm certain lecithin is less harmful than its calories, but I'm not sure by how much. Hydrolyzed lecithin is not dangerous in the same way as trans fats, at least not more than about 10% enough to matter, if I remember correctly. Check PubMed for details. 99.24.223.58 (talk) 03:59, 12 July 2011 (UTC)

Why, if there's a perfectly good emulsifier they could use ? Apparently, we need to dig George Washington Carver up, and put him back to work. :-) StuRat (talk) 03:51, 12 July 2011 (UTC)

Emulsified doesn't taste as good, that's why not. Try it; you'll see. --Trovatore (talk) 06:48, 12 July 2011 (UTC)

I had always heard that GW Carver did not invent PB. Googlemeister (talk) 13:17, 12 July 2011 (UTC)

Even if not, he did invent many peanut products, so improving PB would be right up his alley. StuRat (talk) 05:34, 13 July 2011 (UTC)

May be you should consider taking your peanut butter to your local construction supply store and ask them if you could use their paint mixer :). Dauto (talk) 23:47, 11 July 2011 (UTC)

I learned a few years ago that with simple peanut butter (without whatever chemicals are added to Jif that prevents separation), you just have to mix the concrete and oil with a butter knife for a few minutes (an unpleasant experience because the oil always sloshes out) ... but afterward it does keep mixed for months without separating. I don't know how long the peanut butter has to sit in the jar before it becomes separated in the way you describe. Comet Tuttle (talk) 06:31, 12 July 2011 (UTC)

I would like to avoid that unpleasant task. Especially since spilled oil isn't easy to clean up (detergent is required). But my PB seems to require a stir every time I use it (maybe you refrigerate yours ?). And, I can't just stir up a bit at the top, I've found, or the bottom half that doesn't get stirred keeps getting harder and harder, thus the concrete. So, I have to spend 5 mins stirring it each and every time I use it. That adds up to lots of wasted time and effort. StuRat (talk) 05:41, 13 July 2011 (UTC)

OK, clearly you just need practice. It doesn't take five minutes. Thirty seconds if you're slow. Do it where the spilled oil is easy to wipe up, like on a countertop, and don't get it on your clothes.

Use a knife that's long enough to go all the way to the bottom of the jar, and kind of scoop it up from the bottom, so that the oil falls mostly into the hole left behind rather than slopping over the top (it's not just that the oil is messy; it's also that it's an important part of the peanut butter and you don't want to lose it).

Then once you've made your peanut butter and banana sandwich (mmmmm) stick the peanut butter in the fridge, and you won't have to mix it next time. It's really not difficult. --Trovatore (talk) 20:43, 13 July 2011 (UTC)

But if you stick it in the fridge, then it won't spread because it's cold. I suppose I could microwave it, but then I risk releasing nasty chemicals from the plastic jar. Now I need to find PB in glass jars. StuRat (talk) 02:50, 14 July 2011 (UTC)

It spreads fine cold. Of course if you put it on bread that won't hold up to it, like white bread or the sort of allegedly "wheat bread" that has white-bread-like texture, then you'll have a problem. But who eats white bread? --Trovatore (talk) 05:52, 14 July 2011 (UTC)

Surely the oil that comes out of peanuts is groundnut oil? What's the problem with eating that? --TammyMoet (talk) 09:09, 12 July 2011 (UTC)

When the butter is first made, and I would try an ordinary food processor first to see if it works, it is an emulsion, right? So if you want it thinner for spreading, you add water as you mix. You could add oil as well or instead but then it will be a little more high in calories. Just like making hummus, really. Itsmejudith (talk) 16:50, 12 July 2011 (UTC)

Is Coeliac_disease an allergy?

It's clear to me that it's not wheat allergy, but as a "is an autoimmune disorder of the small intestine", does it count as allergy ("a hypersensitivity disorder of the immune system")? Quest09 (talk) 20:01, 11 July 2011 (UTC)

It seems like there is a lot of confusion regarding this question. Doing a quick google I've found lots of pages that say it is an allergy and some pages even say coeliac disease is caused by a wheat allergy, but not many of them count as what I'd call reputable sources and I think that is incorrect. I think this excerpt has a reasonable and concise explanation. (In short, no, there are some similarities but they are different things.) Vespine (talk) 22:38, 11 July 2011 (UTC)

Question about scintilating scotoma

My younger brother is interested in being a pilot for the US Air Force, but he has rare occassions where he experiences a Scintillating scotoma. He says he gets one about 5-6 times a year and they last from 15 minutes to an hour. Does anyone know if that kind of thing would disqualify him from that kind of a position? Googlemeister (talk) 20:47, 11 July 2011 (UTC)

I believe those are far more common than the literature indicates -- I've looked into it because I get them too every so often. I believe that many people get them without realizing it. It's potentially a problem because if the scotoma passes through the foveal area, you get a small blind spot right at the center of vision. Recommending what to do, however, would constitute medical advice in my opinion, so I won't. Looie496 (talk) 21:46, 11 July 2011 (UTC)

I agree that these are probably fairly common, but I am not sure they are always associated with a stationary blind spot. The occular muscles would need to be paralyzed for that to be the case, unless they were very large compared to those depicted in the article. It isn't medical advice to recommend being honest with the recruiter if asked about vision. I would hope military recruiters would have some kind of a guideline on their intake physical questionnaires, but those aren't known for being read very carefully. The frequency does seem to be high, but I recall that my phosphene, which is much more striking and likely to be remembered, was at least twice as frequent when I was decades younger; perhaps because I was getting more exertion. 99.24.223.58 (talk) 22:57, 11 July 2011 (UTC)

The problem is that when a scotoma occurs in the fovea, you can still see things by looking off to the side, but they won't be sharp -- the sharp part of your visual field is roughly the size of your fist held at arm's length. Reading, for example, becomes very difficult. That's the thing that first clued me in that I was experiencing a scotoma -- otherwise I probably never would have noticed. Looie496 (talk) 23:05, 11 July 2011 (UTC)

Wow! I've totally had this and never knew what it was: Thanks again ref desk:) It only happens rarely and doesn't last very long and I don't get migraines, but it's actually made me wonder if I'm having a stroke or something, lol. (i'm mid 30s so didn't think it was likely).. Now I know! it won't bother me so much. Vespine (talk) 02:33, 12 July 2011 (UTC)

I get these painfree migraine symptoms occasionally too. We have an article on their likely cause, Cortical spreading depression, but this Scientific American article is quite good. Sean.hoyland - talk 03:12, 12 July 2011 (UTC)

The majority of that article seems to require a paid subscription. Googlemeister (talk) 16:44, 12 July 2011 (UTC)

I can read it all without a subscription. Try this single page version. Sean.hoyland - talk 16:55, 12 July 2011 (UTC)

I read it and it was interesting. I sent him the link. Googlemeister (talk) 20:36, 12 July 2011 (UTC)

software filter on imageJ/photoshop

I need this for my research, and it would help my lab a lot. Is there a way to apply a software filter or script to remove out of focus objects (and the background) and keep in-focus particles? The particles in question are fruit flies, viewed from the bottom of a vial. We want to count the number of flies that are strictly in the focal plane of the bottom of the vial, and not count the flies not on the bottom (the ones at the bottom are suffering from the effects of cocaine).

I've tried some resources online, but they seem optimised for cells. I was thinking of also "scoring" the flies -- to see how far away from the bottom they are, so the ones at the bottom (the most in focus) would have a strong score, and the ones that are near the bottom have a weak score. Any variety of attacks would help. Thanks so much! Elle _{vécut heureuse} ^{à jamais} (be free) 22:12, 11 July 2011 (UTC)

This question would probably be more appropriate for the Computing desk, but basically I believe what you want is an edge detection filter. Edge detection works by picking out points that have a strong contrast with neighboring points, and that's what you want. Looie496 (talk) 22:33, 11 July 2011 (UTC)

[8] might be a place to start. Cells are diverse enough that if you want to do better, you might need to look at [9], but that might be a lot more work than simply counting the number of background pixels showing through the region at the bottom from one or more side view(s) of the vial instead of trying to use focus blur from a top or bottom view. 99.24.223.58 (talk) 00:11, 12 July 2011 (UTC)

Sounds related to focus stacking, except you only want to keep/extract the focal-plane of one image rather than extract and merge from multiple. DMacks (talk) 01:06, 12 July 2011 (UTC)

The simpler technique is to grab an undergrad, give him some of the cocaine, and order him to count the flies on the bottom of the vial. You'll find the proper amount of cocaine will produce results at 3 Hz. Comet Tuttle (talk) 06:25, 12 July 2011 (UTC)

Fluorescent lights in a brown-out

We recently had a brown-out (reduced voltage to around 83 V versus normal 110-120V). The incandescent and LED lights got dimmer, but still functioned, and even the compact fluorescents were OK, while the traditional (long tube) fluorescent lights went nuts, flashing frenetically. This was quite annoying, as the basement has all fluorescent lights, and that's where the fuse box is, which is where we wanted to go to investigate the brown out. We ended up using flashlights. So, is there a type of long tube fluorescent light which is more tolerant of voltage swings ? StuRat (talk) 23:11, 11 July 2011 (UTC)

Nope, that's one of the trade offs for their efficiency relative to incandescent and low cost relative to LEDs. 99.24.223.58 (talk) 23:46, 11 July 2011 (UTC)

Compact fluorescents with their electronic ballasts are apt to fail and even ignite when the applied voltage drops that low, unless they are the "dimmable" ones which cost several times as much as generic ones. An intentional "brownout" by a US utility usually aims to drop the voltage far less than to some value way higher than the reported 83 volts, which is likely to destroy many motor operated appliances, unless their circuit breakers or fuses open due to the excess current drawn. Computers and TVs are unlikely to operate at that low a voltage. Gas appliances which use an electric igniter typically do not operate correctly either (some gas ovens spew out gas without igniting it, with the possibility of a gas explosion). Personally, I would kill the power to everything but an incandescent bulb, using it or a voltmeter as an indicator of when the power came back on. The utility would typically trip distribution circuits offline if they had central control of the substation. Maybe there was something weird about the local transformer or connections to the residence, like a loose neutral. Edison (talk) 03:26, 12 July 2011 (UTC)

Do you have any sources supporting the use of "apt" there as meaning more likely than not? 99.24.223.58 (talk) 03:37, 12 July 2011 (UTC)

Here. He used the word correctly. Comet Tuttle (talk) 06:22, 12 July 2011 (UTC)

I could be wrong but I think 99 is asking for a source supporting the claim the electronic ballasts in CFLs intended for a 120V/US supply are apt to fail at 83V Nil Einne (talk) 15:58, 12 July 2011 (UTC)

I considered that providing only 83 volts to a 120 volt bulb was comparable to operating it on a dimmer, although modern dimmers remove portion of the sine wave from each cycle rather than providing a full sine wave at a reduced voltage like the "brownout" in question. Some lighting installations I maintain actually use a huge Variac (rotating variable autotransformer) to dim a room full of incandescent bulbs smoothly. Here is a 1995 reference: [10] "First, be sure not to use compact fluorescent bulbs in circuits that have dimmers - they could present a fire hazard in these uses." Here is a 2009 report on a home which, according to fire investigators, caught fire due to compact fluorescent bulbs controlled by a dimmer. An article from 2008 says "Never use a CFL with a dimmer in the circuit, even if it is set (and kept) at the maximum setting. It will keep you at risk of fire, and will significantly shorten the lifetime of the lamp and the dimmer." General Electric advises against using CFLs on a dimmer if they are not labelled as suitable for such, but understandably they do not mention the fire hazard. I've heard numerous recent reports of early failures of CFLs (without fire) when they are improperly used on a dimmer. Compact fluorescents can also start fires if they are used in a fully enclosed fixture, and they sometimes emit smoke and a burning smell, and have discoloration of the base when they fail in normal use at the end of their service life, per [11]. A "normal " end-of-life CFL burnout may result in smoke being emitted for 30 seconds, sometimes sufficient to set off a smoke alarm, per [12], along with popping sounds, flickering of the light, and a charred base. In October, 2010 the US Consumer Product Safety Commission recalled 124,000 compact fluorescent bulbs sold in 2008 because they could "overheat and catch fire" with no statement that dimmers were involved. Edison (talk) 17:49, 12 July 2011 (UTC)

Thank you. Do you believe it is safe to assume that those which have not been recalled are not capable of igniting exterior flammables at end of life or when used with improperly low voltage or with a dimmer switch? 99.24.223.58 (talk) 18:47, 13 July 2011 (UTC)

Apparently, installation in enclosed areas is a major determinant of thermal bulb failure, and more common in compact fluorescents. Make sure there is adequate ventilation to prevent any electric fixtures, bulbs or otherwise, from igniting their buildings. It's just good interior design. 99.24.223.58 (talk) 22:07, 15 July 2011 (UTC)

Metals

I recently found a piece of metal at the beach. My local jewler did a test, his machine said it was 99% SE. What is SE? — Preceding unsigned comment added by 98.77.106.79 (talk) 23:33, 11 July 2011 (UTC)

Se (formatted with a lower-case "e") is the chemical symbol for Selenium; but that seems very unlikely for a piece of scrap metal. (Pure selenium is rarely used in industrial metallurgy, and almost never occurs in nature). Maybe your report is using some more specialized domain-specific nomenclature. Or, it might mean "something else" - for example, if he performs a standard chemical test for gold, silver, or precious metals, the test may simply indicate any other material as "something else." Nimur (talk) 23:43, 11 July 2011 (UTC)

I'm guessing it just means it's a "stainless (steel) equivalent." Ask the jeweler. 99.24.223.58 (talk) 00:00, 12 July 2011 (UTC)

July 12

Astronomical interferometer wavebands

What are the wavelength or frequency endpoints of the "waveband" designations on List of astronomical interferometers at visible and infrared wavelengths? 99.24.223.58 (talk) 01:45, 12 July 2011 (UTC)

The article Photometric_system has a table. --Wrongfilter (talk) 07:19, 12 July 2011 (UTC)

Evolution

We know many different species evolved in the history of animal kingdom. But why evolution has stopped after the arrival of Homo sapiens? We are the last product of evolution. Why no new species in being evolved? --111Engo (talk) 11:17, 12 July 2011 (UTC)

Your premise is incorrect. Humans are not "the last product of evolution." Evolution continues, new species are being evolved. We are just too short-lived to see it happening. --- Medical geneticist (talk) 11:38, 12 July 2011 (UTC)

(edit conflict):Who says that evolution has stopped and that we are the "last product"? Evolution is a very slow process and is continuing (as far as I know), though only adaptation has been directly observed in real time. We haven't been around for long enough to observe it happening in our species, though tiny changes currently observed might be part of the long-term process. The view of evolution as being a linear process from simplest to highest lifeforms is not generally accepted. The actual path is often very complex, with "dead ends" and convergence. Dbfirs 11:42, 12 July 2011 (UTC)

Evolution is a continuous and ongoing process and did not mysteriously stop with the arrival of Homo sapiens. One example of a new species that is much younger than Homo sapiens is the polar bear, which diverged from the brown bear about 150,000 years ago. Another even younger species is the London Underground mosquito. Gandalf61 (talk) 11:43, 12 July 2011 (UTC)

Is any new biological trait observed among Homo sapiens within the last 10,000 years? --111Engo (talk) 12:19, 12 July 2011 (UTC)

Lactose tolerance in adults, see here. Mikenorton (talk) 12:23, 12 July 2011 (UTC)

(edit conflict) The ability to digest lactose into adulthood (known as "lactase persistence") is a likely candidate. Lactose intolerance#Evolutionary history says it has only reached significant proportions in human populations within the last 10,000 years, linked to the spread of animal husbandry. Gandalf61 (talk) 12:26, 12 July 2011 (UTC)

Also the prevalence of the Sickle cell trait in areas of high incidence on malaria (not sure that this one is proven). Mikenorton (talk) 12:45, 12 July 2011 (UTC)

The sickle-cell trait has different variants evolved at different times. Blondness has evolved within the last 10,000 years or so. μηδείς (talk) 00:05, 16 July 2011 (UTC)

Your initial premise is clearly wrong, as others have pointed out. However, if you want to say, "why do humans seem to be less selected against genetically than other animals?", and we want to grant that perhaps this is true, the obvious answer is that humans are the first animals to develop big enough brains, and some happened to be under the right conditions to develop what we call civilization, technology, and so on, to the degree that we have. Note that it took humans a loooonnggg time to escape "nature, red in tooth and claw," and arguably we haven't escaped it all that well, even so. It is not like Homo sapiens showed up and suddenly humans were the dominant animal on Earth, or suddenly had control over our natural environment. If you want to know, "what factors led to the emergence of the kind of modern, big-city, big-production, big-technology civilizations?" you might take a look at Jared Diamond's Guns, Germs, and Steel which does a very nice job of articulating all of the many factors that had to fall into place for the big, organized societies to rise up in the last few thousand years, which allowed for the kind of apparent "insulation" from natural selection that you are no doubt referring to. Even then, it isn't really perfect insulation, and to call that non-"natural" is a stretch. --Mr.98 (talk) 14:33, 12 July 2011 (UTC)

Indeed. Consider that anatomically modern humans are first observed in the fossil record at about 200,000 years ago and that the first human civilizations developed sometime in the Neolithic Revolution about 10,000 years ago. That means that essentially modern humans existed for 190,000 years before deciding that farming and living in cities would be a good idea, or if you prefer that only 0.5% of human history has been civilized. --Jayron32 15:40, 12 July 2011 (UTC)

Farming in particular is not an obvious thing, as Diamond points out. It's not like early man sat around and said, "you what would be great? To be a farmer, a style of living that has not yet been invented!" It was a slow and difficult process and very early on it did not confer any major benefits over a hunter-gatherer lifestyle. (In fact, Diamond points out, early farmers probably had much poorer diets and caloric sources than did hunter-gatherers.) Furthermore, as Diamond points out, living in farming communities exposes you to all sorts of other risks, like epidemic diseases brought about through close contacts with domesticated animals. Anyway, the whole point is that it's too big (and interesting) a question to sum up as being somehow humans being magically "outside" of evolution. --Mr.98 (talk) 15:47, 12 July 2011 (UTC)

Every other hominid species has been driven to extinction. Everywhere humans have gone, megafauna have disappeared. Climate change may be an issue, but I find the correlation worldwide striking. Most other primates and much fish are in danger of disappearing. And as Richard Dawkins has pointed out (The Extended Phenotype), as we select plants and other animals, they select us just as surely. Imagine Reason (talk) 00:05, 13 July 2011 (UTC)

Hmm, looks like the arrival of Homo sapiens was an evolutionary accident. There is a solution. --111Engo (talk) 01:13, 13 July 2011 (UTC)

wireless power transmission

what is the circuit diagram ofireless power transmission??? — Preceding unsigned comment added by Maryam chaudhry (talk • contribs) 12:19, 12 July 2011 (UTC)

what is the circuit diagram of wireless technology????? — Preceding unsigned comment added by Maryam chaudhry (talk • contribs) 12:21, 12 July 2011 (UTC)

Wireless energy transfer gives some detail but not a circuit diagram. At its simplest, just two coils would be sufficient. Wireless technology often refers to the transfer of data over a wireless network, but I assume this is not what you were asking about. Dbfirs 15:47, 12 July 2011 (UTC)

Here is a diagram by Tesla. Cuddlyable3 (talk) 09:48, 13 July 2011 (UTC)

Electromagnetic power transfer of substantial energy is likely to involve thermal or ionizing radiation. 99.24.223.58 (talk) 18:53, 13 July 2011 (UTC)

How shall we name the phenomenon?

When material "Escapes" from inside the organ through it's membrane --- out. ?

Thanks. — Preceding unsigned comment added by 79.181.33.137 (talk) 13:17, 12 July 2011 (UTC)

Do you refer to the serous membrane? EverGreg (talk) 13:27, 12 July 2011 (UTC)

Osmosis is a method of passage through a membrane. Wanderer57 (talk) 13:33, 12 July 2011 (UTC)

Neither really describes the phenomenon, if it exists without rupture of the cell walls. Osmosis is only water passing through the semi-permeable membrane, and serous fluid is a secretion rather than an escape, but I'm at a loss to provide a better answer. Dbfirs 15:57, 12 July 2011 (UTC)

Take a read of Secretion this refers to vesicle fusion and exocytosis. Graeme Bartlett (talk) 22:02, 12 July 2011 (UTC)

Yes, this could be interpreted as "escapes", so it does answer the OP's question. Please ignore the second part of my comment above. Dbfirs 23:22, 13 July 2011 (UTC)

Red-violet

Looking through a box of crayons, I encounter a color dubbed "red-violet". Red and violet are on opposite ends of the visible light spectrum. However, violet is a mix of blue and red. How can there be a cycle in a spectrum? Where on the spectrum does the "red-violet" color exist? 75.73.225.224 (talk) 14:33, 12 July 2011 (UTC)

I believe you're confusing two things: the spectrum as a physical phenomena, and the colors our brain interpret the physical phenomena as being (as qualia). The human eye does not use a linear spectrum to interpret light; it uses a series of rods and cones which fire signals depending on what hits them. It's the way the eyes and brain are wired which makes the ends of the spectrum appear to loop together. Color vision has a lot more detail on this sort of thing. You might also look at Color_wheel#The_color_circle_and_color_vision, which discusses a bit the difference between actual human color vision and a perfectly looped color wheel. --Mr.98 (talk) 14:43, 12 July 2011 (UTC)

In the image you linked, the ends of the spectrum meet at black because both ends fade into invisibility. That's unrelated to the "line of purples". -- BenRG (talk) 16:36, 13 July 2011 (UTC)

Other good reads in this regard are Imaginary color and Line of purples. There are many "non spectral colors" in the world, besides the purples are the browns and the pinks, and things like that. They are usually made (spectrally) by combinations of lights of many different wavelengths, though some combinations are actually impossible (called Impossible colors). For example, there is no "reddish-green" color. --Jayron32 15:35, 12 July 2011 (UTC)

I have often wondered if the perception of a "cycle" in the colors we can see might have something to do with frequency aliasing. Red light drifts out of our visible range at almost half the frequency at which blue light starts to drift into our visible range. So, it seems plausible that we might be perceiving a "dropped octave" helping us connect the red back to the purple to the blue. But, I don't think this is well supported by physiological models of the perception of color, nor by experiment with monochromatic light at the edges of our perceptual ranges. It's difficult to find scholarly research, as most research work related to vision, and keyworded with "aliasing", tends to focus on spatial aliasing and moire patterns. Nimur (talk) 21:13, 12 July 2011 (UTC)

The illusion of a cycle comes from the fact that there are thee primary colors (because there are three different cones in our eyes) and three secondary color between them forming a triangle that can be easily deformed into a circle. If there were four primary colors and six secondary colors between them forming a pyramid, deformation into a circle would be impossible breaking the illusion of a cycle. Dauto (talk) 01:46, 13 July 2011 (UTC)

84,000 chemicals

What are the names and uses of the 84,000 chemicals in use today in the USA? — Preceding unsigned comment added by 75.181.43.47 (talk) 15:10, 12 July 2011 (UTC)

All of them? --Jayron32 15:29, 12 July 2011 (UTC)

I started writing a list of the usage of dihydrogen monoxide got about 1% of the way and then my browser crashed. Nil Einne (talk) 16:05, 12 July 2011 (UTC)

Here are few off the top of my head to get you started. Acetone, Benzene, Chloroform, Diethyl ether, ethane, Formaldehyde, gasoline, heptane, Iodine, kerosene, liquid nitrogen, Monosodium glutamate, naptha, oxygen, pentane, Salicylic acid, taurine. Googlemeister (talk) 16:33, 12 July 2011 (UTC)

If you're looking to round out the alphabet, I suggest jasmone, quinine, rubidium chloride, uranium hexafluoride, vanadium carbide, water, xenon hexafluoroplatinate, yttrium aluminium garnet, and zinc telluride. -RunningOnBrains^(talk) 18:10, 12 July 2011 (UTC)

This question is perhaps more sensible than it sounds. I believe the question refers to the TSCA Inventory, the list of chemicals registered under the Toxic Substances Control Act of 1976, which includes about 84000 chemicals. The full dataset can be downloaded from the US government here. --Colapeninsula (talk) 16:53, 12 July 2011 (UTC)

Then we need to correct the OP's view that chemicals are all bad, perhaps by pointing that a lot more than 84,000 chemicals exist, including those that make up the human body and everything else around us. Most of them are quite nice chemicals. HiLo48 (talk) 17:22, 12 July 2011 (UTC)

I would hazard an educated guess that there are indeed more than 84,000 times 84,000 chemicals known to man, especially if you include theorized compounds not yet isolated. -RunningOnBrains^(talk) 18:10, 12 July 2011 (UTC)

FWIW, there are more than 60 million chemical compounds listed in Chemical Abstracts: http://www.cas.org/newsevents/releases/60millionth052011.html — Preceding unsigned comment added by 148.177.1.212 (talk) 19:15, 12 July 2011 (UTC)

Of course, all this also depends on your definition of "in use". But I believe Colapeninsula has stumbled upon the answer the OP was looking for. -RunningOnBrains^(talk) 19:13, 12 July 2011 (UTC)

I can't help but wonder how HiLo48 knew the OP holds the view that chemicals are all bad. Wanderer57 (talk) 20:35, 12 July 2011 (UTC)

A reasonable conclusion to draw based on Colapeninsula's post above about where the 84,000 figure came from. Unless you have other suggestions....? HiLo48 (talk) 23:21, 12 July 2011 (UTC)

Thank you HiLo48, I missed that turn. Wanderer57 (talk) 01:24, 13 July 2011 (UTC)

The view that some chemicals are harmless also invites some refutation. The classic data for this is a study by Rick Relyea of the University of Pittsburgh, who found that, like the EPA said, tadpoles were not harmed by ordinary environmental levels of Sevin (carbaryl, the stuff they were making in that tank that blew up in Bhopal). But in the presence of substances that indicate the presence of predators, it is quite lethal!^[13] Another example involved the interaction of melamine with a second related chemical in Chinese pet foods and tainted human foodstuffs, which lock together much like the bases of DNA to form huge two-dimensional flakes that harm the kidneys when they are excreted. What this means is that you can't honestly say "this chemical is safe". You can only say that the chemical seems safe under some set of circumstances you've investigated. Since you can't investigate every combination of two chemicals, you cannot honestly say that using any given chemical is safe - unless, that is, it is some substance like water which has been present in the natural environment long enough for evolution to have had a fair chance to direct what the organism does with it, and even that only goes so far (e.g. water toxicity). Sevin was not safe for amphibians, despite testing; melamine was not "mostly harmless" for humans, despite testing. There's no way to detect these sorts of things except by exposing people to them and waiting until someone tracks down who was injured or killed. Wnt (talk) 22:47, 12 July 2011 (UTC)

Of course, almost anything can be unhelpful in the wrong place, wrong concentration or at the wrong time. HiLo48 (talk) 23:21, 12 July 2011 (UTC)

Besides who said anything about 'this chemical is harmless' or 'some chemicals are harmless'? Nil Einne (talk) 00:33, 13 July 2011 (UTC)

You don't need to work that hard to prove that any chemicals can be made dangerous. Here's simpler : Ten tons of the solid form of virtually any chemical will crush anybody it happens to fall on. APL (talk) 00:52, 13 July 2011 (UTC)

Only part of the answer thought and the easy part. A quick look at the list and the article suggests my belief there is no centralised database of every single use of every single chemical on that list, is correct. Trying to compile a usage of a list of ~84000 chemicals includings things like Formaldehyde, D-Glucose, Lanolin, C.I. Acid Orange 1 is like people have been saying from the beginning.... Nil Einne (talk) 00:29, 13 July 2011 (UTC)

A few chemicals I found to be individually and severally delightful: (In one Caldwell-Luc operation, in a renowned hospital): Morphine, Cocaine, Nitrous Oxide, Vallium, and possibly local anesthetics not noted or remembered. These chemicals made it amusing and pleasant to have a surgeon use a small chisel, while I was quite conscious, to punch a hole above the upper teeth into a sinus creating an outlet to prevent recurrence of Sinusitis, a procedure that would have obviously been unendurably painful without anesthesia. I guess it was still painful, but with the nitrous it also seemed funny. Edison (talk) 04:07, 13 July 2011 (UTC)

The druge that Edison mentions cross the blood-brain barrier once ingested. The article Addiction can be relevant where it notes that "Pleasure and enjoyment would have originally been sought; however, over a period of time involvement with the substance or activity is needed to feel normal." Cuddlyable3 (talk) 09:40, 13 July 2011 (UTC)

The Chemical Abstracts Service registries have a running tally on their web site. It's in the low 61 millions at the moment. 99.24.223.58 (talk) 18:58, 13 July 2011 (UTC)

Sycon

Is Sycon radially symmetric? — Preceding unsigned comment added by 122.179.68.190 (talk) 16:01, 12 July 2011 (UTC)

Are you referring to a genus of sponge? If so, then it appears from diagrams that at least the arms of some genus members are typically radially symmetric, if not the entire organism. -RunningOnBrains^(talk) 17:56, 12 July 2011 (UTC)

Natural gas ownership in the US

I'm an American, and as I suspect is the case for most people like me, I have one and only one choice when it comes to who is my natural gas provider. In other words, they have a monopoly on my area. I would suspect this is the case in most localities (I have no reason to believe my locality is exceptional). To my own sense of right and wrong (which I realize has no jurisdiction on reality), this only seems fair if the company owns the land where the natural gas came from and paid to lay ALL the pipe to the houses from which it collects money. Do the natural gas companies in fact usually own the land from which they extract their product? If not, how does one company get into such a favorable position over all other hopefuls? 76.27.175.80 (talk) 18:23, 12 July 2011 (UTC)

There are several related issues which confounds answering all of your questions.

• First, natural gas is extracted from the ground by a company who owns the mineral rights to do so. Mineral rights is a tricky thing, but generally different entities may own the surface of the land and the land underneath. This entity which extracts the oil and/or gas is usually a completely private company, and can be of any size, from a small "mom-and-pop" operation to a large multinational corporation like BP or Exxon/Mobil. These extraction companies sell the natural gas to the company that sells it to you. That is, the "Gas Company" doesn't extract and refine the gas, they are simply the retailer. They buy it on the wholesale gas market, much the same way that Walmart doesn't actually make the blue jeans you buy there.
• Secondly, distribution of natural gas to your house is managed by a public utility. In the U.S., public utilities are semi-private companies which are heavily regulated by the government; in exchange for the monopoly they have on distribution, they give up a lot of their own freedom with regards to the rates they charge, how much profit they make, etc, which are regulated by the state governments. The rationale they have over distribution is that, unlike many goods which are efficient to be produced and distributed by a single company, like say a car or bread or landscaping services, utilities like gas require a complex distribution system which would be HIGHLY inefficient if you had, say, several companies distributing gas to your city.
• Lets say you decide to buy your gas from Joe's Natural Gas. So Joe's comes and lays pipes to your house. Lets say your neighbor decides to buy from Bill's Natural Gas. Does Bill's now lay another set of pipes to your neighbor's house? Does every company have its own network of pipes? What a mess if every time someone wants to install natural gas, they pick a company and that company has to find a way to dig giant trenches all over the place to lay new pipe! Furthermore, what if you decided to leave Joe's and take your business to Bill's. Does that mean Joe's comes and digs out all of the pipes that used to bring you gas, and Bill's has to lay new pipe? What a complete mess that would be.
• Instead, a single company is in charge of distributing natural gas to a jurisdiction. They lay one set of pipes, and everybody buys from them. Yes, it isn't competitive, but in this case competition isn't so great, since the result of having an open market on public utilities is a rediculously inefficient thing. So certain services, such as power, water, electric, solid waste removal, local landline phone services, etc. are managed as public utilities. Since there isn't a "free market" regulating price, these services are heavily regulated by the state instead.
• Thirdly, the company that laid the pipe isn't necessarily the company selling you the gas. Instead, the company selling you the gas probably leases the pipe from the pipeline company.

As a final note, you may find Oil and gas law in the United States an interesting read. --Jayron32 18:50, 12 July 2011 (UTC)

Thanks for that very informative answer, Jayron32. The "Gas Company" retailer from your first bullet, is that the same entity as the semi-private "Public utility" in your second bullet? 76.27.175.80 (talk) 19:05, 12 July 2011 (UTC)

Yes, for example SCANA is a gas and electric company which serves much of the Southeastern U.S. My personal Gas Company is their subsidiary PSNC Energy, which serves North Carolina. --Jayron32 20:19, 12 July 2011 (UTC)

All this should be compared and contrasted to propane heating and cooking, as my parents in Connecticut have; this can be delivered by truck and safely stored in a tank on their property, therefore, there are several companies all equally capable of delivery. Thus: competition. I'm not sure why the same can not be done with natural gas, but I'm sure there are technical reasons.-RunningOnBrains^(talk) 19:12, 12 July 2011 (UTC)

I do see large AmeriGas tanks sometimes next to a non-residential building where I live. From UGI Corporation, that appears to be the largest propane marketer in the US. 76.27.175.80 (talk) 19:21, 12 July 2011 (UTC)

Propane is distributed differently for several reasons. See Propane#Propane_risks_and_alternate_gas_fuels. While natural gas leaks are also dangerous, methane being lighter than air tends to dissipate. Propane is heavier than air, and so tends to sink and concentrate. Contrawise, propane is well suited for tank distribution since it can be liquified while natural gas cannot, being above the critical temperature at which liquid natural gas can form. As a result, compressed natural gas is much less efficient, in terms of heating capacity per unit volume than liquid propane, which is why natural gas is more suited for pipelines than tanks. --Jayron32 20:19, 12 July 2011 (UTC)

Cool, it didn't occur to me that natural gas could not form a liquid at ambient temperature. To paraphrase Bill Nye, Now I knowwwwwwwww -RunningOnBrains^(talk) 20:45, 12 July 2011 (UTC)

Keep in mind also that there could logically be competition between electric and gas for cost of heating and cooking, although in many cases one utility provides both services. μηδείς (talk) 20:03, 13 July 2011 (UTC)

I live in a state where the two services are provided by two different companies, and there is no competition between them; gas heating is a LOT cheaper than electric. In everywhere that I have lived, electric heating is always the most expensive option; where I lived in New England previously there wasn't a widespread natural gas infrastructure, so everyone heated their homes using something other than electric (heating oil, coal, wood, concentrated wood pellets, etc.) because heating with electric was prohibitively expensive. The only place where electric heating makes economic sense is in states where you literally almost never have to use it (say, Florida). Otherwise, its always the worst option. --Jayron32 20:16, 13 July 2011 (UTC)

There are a lot of places where the two are under the same company, such as Pacific Gas and Electric Company, Dominion Resources and Constellation Energy. Washington Gas has recently gotten into electricity brokering, in addition to selling gas. Acroterion (talk) 20:22, 13 July 2011 (UTC)

True, but the salient point in my post was that regardless of your own particular arrangement in how you purchase your energy needs, electric heating plain sucks in terms of cost. If you live in a place where you need to heat your home for many months at a time, and if (hypothetically) your home only had electric heaters, you could recoup the cost of installation in a matter of a few years by installing literally ANY other heating system. The idea that competition between electric and gas for heating one's home would somehow make electric heating reasonably priced (which is what Medeis seemed to be arguing) is plainly not true. --Jayron32 22:46, 13 July 2011 (UTC)

Agreed, I've never encountered a situation (in the US Mid-Atlantic area) where electricity could beat natural gas for operating cost. The only variant I've seen where electricity can win is with large buildings equipped with water-loop heat pumps, where heat is only needed for a relatively short part of the year, as compared to air conditioning, so the additional cost of a gas connection is unattractive compared to the already-required cost of a large electrical service for the chiller-cooling tower units. In such circumstances, where much of the building's internally-generated occupancy heat is simply moved where it's needed, the boilers can be startlingly small, and the operating cost penalty ignored. Acroterion (talk) 15:56, 14 July 2011 (UTC)

The other place where electric heating makes sense is if you've got cheap hydropower. Both Quebec and Washington State meet that critera. --Carnildo (talk) 01:33, 14 July 2011 (UTC)

The thing to note about electric heat is that any electric plant ultimately produces waste heat (unless it uses cogeneration and physically distributes a liquid). This is because of limitations of generating usable work from difference in heat as per the Carnot cycle. Whenever electric heat is used, some of the energy of the original fuel goes down the river or into a cooling pond. Wnt (talk) 05:12, 14 July 2011 (UTC)

I was simply pointing out that there is a choice, even if in certain locales one has a huge advantage over the other. But that situation shouldn't be taken for granted--it is caused by intentional policy. The high price of electricity in various locations is a result of regulation, not of the inherent costliness of, say, nuclear power. If you want competition to drive down prices you have to adopt a laissez-faire policy. It won't happen in artificial "managed competition" schemes such as the CLEC debacle in phone service in which MCI's massive fraud destroyed AT&T. μηδείς (talk) 18:43, 14 July 2011 (UTC)

Earth-Moon formation contribution to the asteroid belt?

I have a theory based on no math or research, just a hunch.

Setup: I like the theory of the Moon being formed by a collision of a Mars sized planet with the Earth of the time.

Question: Could some of the material knocked off both parties have continued on and become part of (or all of) the Asteroid Belt between Mars and Jupiter? Since the collision was apparently tangential perhaps all the energy was not dissipated in the collision.

Thanks in advance for setting me straight! :) — Preceding unsigned comment added by EZ Pickins (talk • contribs) 22:25, 12 July 2011 (UTC)

No. The fragments fell back to earth due to earth's gravity. Any small fragments that might have escaped earth's gravity would have been left in a earth crossing orbit. They would not be in a orbit between Mars and Jupiter. Dauto (talk) 23:27, 12 July 2011 (UTC)

Sure, it could have happened. (Not to assert that it did. Insufficient data). Fragments with greater than escape velocity naturally would have escaped, and if the directions and velocities were amenable, the escaped fragments could have become part of the asteroid belt. Edison (talk) 03:56, 13 July 2011 (UTC)

How do you propose those fragments found their way to orbits between Mars and Jupiter? Dauto (talk) 05:43, 13 July 2011 (UTC)

If you have an object in orbit and apply an instantaneous thrust to it, it will end up in an orbit that crosses the starting orbit at the point where the thrust was applied (this is obvious if you think about it - how could it end up in any other kind of orbit?). That means a piece of the Earth thrown away from the Earth by the impact would end up in an Earth-crossing orbit. There are various things that could cause that orbit to change over the billions of years since the formation of the Moon, but I wouldn't expect a significant amount of material from Earth to have ended up in the asteroid belt. The asteroid belt is almost entirely made up of material that never coalesced into planets. --Tango (talk) 11:57, 13 July 2011 (UTC)

There is no guarantee that something which gets a big smack near the Earth won't get another big smack from something else before it returns to the starting orbit. No isolated system at all. The early solar system had millions of rocks of varying sizes hitting one another, with a few objects getting double tapped randomly such that they landed in this orbit or that orbit, beyond simple orbital mechanics. Edison (talk) 14:50, 13 July 2011 (UTC)

Sure, it's theoretically possible, but entirely improbable. At best, a totally negligible percentage of the asteroid belt was formed this way.--Goodbye Galaxy (talk) 15:26, 13 July 2011 (UTC)

Exactly. The probability that that is the correct explanation for the origin of the asteroid belt is somewhere between zip and nil. Dauto (talk) 19:48, 13 July 2011 (UTC)

I said, in the very comment you are replying to, that there are various things that could cause the orbit to change. Another collision is actually the least likely - space is big, so things don't collide very often. Gravitational interactions and light pressure from the sun are more likely to cause significant changes. --Tango (talk) 14:04, 14 July 2011 (UTC)

I'm not by any means an expert here, but I think the issues are being oversimplified a bit. You can't take any arbitrary orbit within the solar system and expect it to persist for billions of years -- every orbiting object is constantly perturbed by all of the planets, most strongly by Jupiter. There probably are only a few types of orbits that are stable over the long term, and they seem to be spaced in a more or less regular way; see Titius-Bode law. All of the putative stable orbits are occupied by planets except one, which corresponds to the asteroid belt. So I think it might be possible for an asteroid to start with a radically eccentric orbit which would go through a series of perturbations until eventually it either was ejected from the solar system or ended up in the asteroid belt. Looie496 (talk) 20:39, 13 July 2011 (UTC)

The problem is not that it is not possible. The problem is that it is highly unlikely. Dauto (talk) 21:55, 13 July 2011 (UTC)

I think some people here are trying to "move the mountain to Mohammed", as some put it (though I've heard that's not a legitimate Muslim story...) Think for a minute: what evidence do we have that the Earth was in its present orbit - or that Jupiter was in its present orbit, for that matter? The exoplanet data we've been hearing about involves lots of stories of planets that must have formed one place and gone another. And the Earth, having been big enough to clear an orbit before the collision, yet being struck so badly, must have been in some crazy elliptical orbit at one point, mustn't it? Wnt (talk) 05:09, 14 July 2011 (UTC)

You seem to be trying to come up with a way in which the Earth-Theia collision could have resulted in the asteroid belt, which is backwards thinking. You should be considering the asteroid belt and trying to think of a way it could have been formed. It being made up of planetesimals that never coalesced into a planet is a very simple explanation for pretty much everything we observe, so we don't need to look any further. --Tango (talk) 14:04, 14 July 2011 (UTC)

July 13

Cultural or instinctive - revulsion at homosexuality

I recently read comments on a forum where a large number of people used the argument "I find the idea of homosexual acts disgusting, therefore homosexuality must be absolutely wrong (or evil)" in one form or other. This is obviously a flawed argument; I could use it to say that celery soup is absolutely wrong or evil! I found it interesting that so many people find the idea of homosexual acts disgusting though. Especially since though I support gay rights and equal treatment for homosexuals at a deep level I feel revulsion at the thought of homosexual acts.

Is this revulsion some deep instinct, maybe something to do with a persons sexuality? I have heard some homosexuals say that they find the idea of sex with someone of the opposite sex disgusting, which would support this. On the other hand it is clearly not universal as there are bisexuals. It seems there is some evidence that it is instinctive and some that it is learned or cultural. Has any research been done on this. -- Q Chris (talk) 12:35, 13 July 2011 (UTC)

Dont Know of any studies, but my my analysis(guess): Feeling disturbed with homosexual interactions may help choose the a partner of the right sex, (i.e. on the straight and narrow path) especially as a strong attraction for both sexes must be coded in the same genome. As most people judge "what's disgusting for me to do is disgusting even if you do it" instinctively this may explain homophobia.

fMRI data indicates that homosexual's brains respond in almost exactly the same way as members of the opposite sex will to smelling estrogen/testosterone. May be in homosexuals the instinctive dislike also is reversed.Staticd (talk) 13:12, 13 July 2011 (UTC)

My instinct is that disgust towards homosexuality is almost certainly a learned trait. Within human culture, it is not universal at all; many cultures have no problems with it at all (see Ancient Greece) and some practices, which in some cultures are viewed as homosexual, are commonplace in others (Cheek kissing among males in say France, or hand holding among Arabic males). Among non-humans, behavior that would be described as "homosexual" is commonplace; male dogs will copulate with each other (heck, a male dog will copulate with a lampost) and such behavior is common among the Bonobos, which are genetically among the closest relatives of humans. Negative reactions towards homosexuality are likely strongly corrolated towards cultural reactions towards non-procreative or extramarital sex in general. --Jayron32 14:50, 13 July 2011 (UTC)

That's a very good point about other cultures. At first I was surprised at how such a culturally learned feeling could seem so instinctive and natural - but then it feels just as natural and instinctive to feel revulsion at people eating Witchetty grubs, or locusts -- Q Chris (talk) 21:15, 13 July 2011 (UTC)

Well bearing in mind that the acitivity is ABNORMAL, its not surprising that many people are nauseated by it. — Preceding unsigned comment added by 78.148.128.45 (talk) 15:09, 13 July 2011 (UTC)

You may wish to read the messages to which you are responding...you may learn something. DMacks (talk) 15:23, 13 July 2011 (UTC)

Define abnormal. Dauto (talk) 15:37, 13 July 2011 (UTC)

Abnormal means most people dont do it. — Preceding unsigned comment added by 78.148.128.45 (talk) 16:29, 13 July 2011 (UTC)

Most people don't ride unicycles. Do you find unicycle-riders disgusting? AndyTheGrump (talk) 16:32, 13 July 2011 (UTC)

Of course they are disgusting: sticking a wheel with a pole attached up thier backsides: what could be more abnormal?

Most people don't get college education, most people don't run marathons, most people don't play the piano, most people don't work for the navy, most people don't sing at church choirs, most people don't travel abroad, most people don't ... you get the point. Do you find any of those activities nauseating? Obviously you haven't given that topic too much thought. Why should anybody care about what you think then? Dauto (talk) 19:08, 13 July 2011 (UTC)

I believe the bad attitude tends to be stronger in men than in women, and a major part of it is a dislike of the idea of being "hit on" by another man, because it places one in a feminine role and can easily be seen as a challenge to one's own masculinity. Looie496 (talk) 16:37, 13 July 2011 (UTC)

Many men get rather turned on by the sight of two women making out, and will pay good money for pornos portraying such activity, so for them, homosexuality per se is no bad thing. But when it's two guys - "oh, that's different, it's unnatural, it's filthy". Yeah, right. -- Jack of Oz ^{[your turn]} 19:46, 13 July 2011 (UTC)

Metamorphosis in humans

The metamorphosis of amphibians is well known, triggered by thyroid hormone, and involves such characteristics as the development of a new stratified layer in the skin, the differentiation of the cerebellum, and various skeletal alterations (see anuran for a more complete list). In humans, these alterations are less apparent, as they occur during fetal development - the same changes in the skin, for example, occur between weeks 9 and 24 of gestation (see [14] - the tadpole-like epithelium is periderm, beneath which a thick stratified epithelium forms, followed by apoptosis of the periderm). At least in mice, responsiveness to thyroid hormone is important for cerebellar maturation.^[15] Also, a transient opercular flap (expanded second pharyngeal arch) seems to be characteristic of higher vertebrate embryology.^{PMID 21632625}

Some questions...

• The situation with thyroid hormone in human embryos is complex: the placenta develops to be fully supplied with maternal blood by 12 weeks or so, bringing in a supply of thyroid hormone; but the embryo also supplies its own hormone by 20-22 weeks. There are multiple receptors. What is the closest we can come to seeing a "paedomorphic human"? (i.e. one not undergoing "metamorphosis", though human paedomorphism is more typically used to refer to heterochrony later in development)

• Regeneration of limbs is famously lost in frogs after metamorphosis. Looking at the development of human embryos,^[16] it is apparent that they have well developed limbs long before the apparent metamorphosis as defined by the skin transformation. Do these limbs regenerate if severed? (Admittedly, I doubt experimental evidence is available, but you never know what kinds of accidents will happen...)

• Am I reinventing the wheel here - has someone published a comprehensive list of similarities between human fetal developmental events and metamorphosis? Wnt (talk) 14:23, 13 July 2011 (UTC)

Not a biologist, but I remember the notion from high school bio "Ontogeny recapitulates phylogeny". Edison (talk) 14:44, 13 July 2011 (UTC)

Annihilating a human

The size of the blast fireball.

Sort of a silly question. If you were to turn the mass of an average human (say, 170 pounds) into energy, how big would the resulting explosion be? --Goodbye Galaxy (talk) 15:21, 13 July 2011 (UTC)

The Tsar Bomba, the largest nuclear bomb ever detonated (1,400 the size of Little Boy and Fat Man combined), had a yield of 50 megatons of TNT. By E = mc², this equates to ca. 2.3 kg of mass converted to energy. A 170 kg mass completely converted to energy would result in about 1.5 × 10¹⁹ joules of energy (about 7600 megatons of TNT). According to Orders of magnitude (energy), this is about the same as the yearly electricity production in the U.S. as of 2005. -- 174.31.204.164 (talk) 15:42, 13 July 2011 (UTC)

Niiiice (you switched pounds for kilos, but I get the picture). Thanks. --Goodbye Galaxy (talk) 15:51, 13 July 2011 (UTC)

Also, if you are annihilating the human with an equal sized mass of antimatter, it would be 2x as big because the antimatter mass would count as well. Googlemeister (talk) 15:51, 13 July 2011 (UTC)

(EC x 2) The question was about 170 pounds, i.e. about 77 kilograms, which is equivalent to about 7 exajoules. However, I don't see how you could easily convert nearly all of the human into, say, photons without annihilating it with 77 kg of antimatter, in which case the total mass involved would be about 154 kg, which is equivalent to about 14 exajoules, which is close to your answer by coincidence. Red Act (talk) 15:59, 13 July 2011 (UTC)

Yeah, I should have clarified in my question that the annihilation was due to magic. --Goodbye Galaxy (talk) 16:03, 13 July 2011 (UTC)

DNA question

What % of the weight of a human would their DNA be? Is it a significant amount or something like 1/1,000,000th of a percent? Googlemeister (talk) 15:37, 13 July 2011 (UTC)

According to this page there are about 6 x 10^-12 grams of DNA per human cell. There are probably a few trillion cells in the human body (not counting red blood cells, which lack nuclear DNA); estimates are imprecise. If those numbers are correct, you get several grams of DNA, a significant amount, although well under 1% of the total. Looie496 (talk) 16:28, 13 July 2011 (UTC)

(ec)It's easier to figure this out than look it up (I said before starting ;)) ... though someone ought to chase down a number so we can cite it in the article. To begin with,

TMP = 320.1926 g/mol; dAMP = 331.222 g/mol; dCMP = 307.197 g/mol; dGMP = 347.2243. A molecule of water (18.01528 g/mol) is lost from each of these on polymerization, and we always find A with T, G with C. That gives us 615.384 g/mol for a T-A base pair and 618.391 for a G-C base pair. The precise mass of one genome will thus depend on the GC-content very slightly, and of course will be proportional to the genome size. The first of many confounding biological factors creeps in when we realize that "the" genome size doesn't exist; NCBI listed 3,101,788,170 bases in a very nearly complete reference sequence, but individuals vary, and apparently there are still a few hard-to-sequence repetitive regions missing small bits of information.^[17] Still, to boldly take that number and plunge ahead, and using 41% for the G+C content (I can't find a more precise number - due to the repeat problem, and the fact that repeats have very unusual G+C contents, there may not be a better number even from all that sequence data) we get:

3101788170 * (0.41 * 618.391 g/mol + 0.59 * 615.384 g/mol) / 6.0221415 × 10²³ /mol = 3.17 × 10^-12 grams

This is the mass of a haploid genome per cell (such as sperm); most cells carry 2n (in G1 arrest) or 4n (G2 arrest, while preparing for mitosis, etc.); some carry vastly more (trophoblasts, etc.). But on average the cells get bigger in proportion to the number of genomes they have, so it's more the type of cell that matters.

For example, a sperm head is roughly 4-5 micrometers long; from a drawing of the typical sperm it appears 25/40 as wide and 13/40 as thick (but with a hollow spot in front, so let's call it, oh, 10/40);^[18] this gets us 4.5*(5/8*4.5)*(1/4*4.5)*(4/3)*(3.14) = 59.6 cubic micrometers = 59.6 x 10^-12 cubic centimeters (=ml). (error corrected, sorry!) So one genome per sperm head works out to about 3.17 x 10^-12 / 59.6 x 10^-12 = 0.0532 g / ml = 53.2 g/l = 5.32% w/v. But as you see from this work, I could be off by quite a bit!

Now the "typical mammalian cell", according to cell nucleus, has a 6 micron round nucleus which is 10% of the volume. 6 * 6 * 6 * (4/3) * (3.14) = 904 cubic micrometers. Twice the DNA in such a space is still only 6.28/904 = 6.94 grams per liter, or 0.694 % (w/v). And in the cell as a whole it is one-tenth of that - 0.694 grams per liter or 0.0694%. Of course, that's not counting the extracellular space, which in some tissues is quite substantial... Wnt (talk) 16:52, 13 July 2011 (UTC)

Using fractionally distilled oil products to fractionally distill crude oil

It takes heat energy to bring a barrel of crude oil to the temperature required to fractionally distill it obviously, and the products of the fractional distillation have the ability to be used as energy. But how much crude oil can you fractionally distill from the energy you get out of whichever hydrocarbon is used as fuel after fractionally distilling one barrel of crude? In other words, you start with one barrel of crude, you use unknown energy given to you to fractionally distill it, you get products, including whatever X amount of product that can be used for fractionally distilling crude oil. How much crude can you distill with X? 20.137.18.50 (talk) 20:29, 13 July 2011 (UTC)

A lot more complex <g> especially since some of the products from the crude are, indeed, used as fuel in the process. And they do not use one single hydrocarbon for the purpose. Cheers. Collect (talk) 20:33, 13 July 2011 (UTC)

(edit conflict)That is a complex question, and you aren't likely to get a solid answer in just a single number or quick sentenece of explanation. It depends a LOT on which distillation product you are using (propane, butane, kerosene, gasoline, etc.) as your heating source, and what the particular make-up of the crude is (different crude from different parts of the world have WILDLY different compositions). I'm sure that, if given a specific formulation of crude, and a specific product of that crude, you could work it out trivially, but there's no guarantee that your answer will be widely applicable. For example, if you know that your crude is 10% propane, and you know that propane generates 50 megajoules per kilogram, and you know how many joules of energy you need to fully distill the crude to its final products, you can work out if the system is self-sustaining or not. However, such calculations would be purely pedagogical in the sense that the exact same set of calculations would need to be done for each application. There's no universal number that you could apply to all crude. --Jayron32 20:39, 13 July 2011 (UTC)

Yes, I didn't say it in so many words, but the question in my head as I was forming the question was about how self-sustaining or efficient the average refinery's average blend is, in terms of how much energy product is left after they use energy to make their products. It seems like when you add up all the energy that really goes in, not only considering the refining (which is the only thing I considered in my question), but also all the energy that goes into getting it out of the earth and transporting the crude from the drilling site to the refinery and from the refinery to the points of consumption for each type of product, the whole process must be very negative.20.137.18.50 (talk) 20:44, 13 July 2011 (UTC)

Non-negative net value of energy from petroleum prodution by a long shot. Elsewise, the industry would cease to exist. Collect (talk) 20:53, 13 July 2011 (UTC)

Energy returned on energy invested is an article on the topic. DMacks (talk) 21:41, 13 July 2011 (UTC)

If it was negative, it would not be a source of energy. Dauto (talk) 21:48, 13 July 2011 (UTC)

Waste heat recycling is an essential component of any production chemical engineering process, but the most efficient refinery processes are usually closely held trade secrets which depend on the detailed geometric configuration of the particular refinery. 99.24.223.58 (talk) 00:43, 14 July 2011 (UTC)

Practical Applications of Room-Temperature Superconductors

I'm writing a science fiction story in which a society with similar technological development to ours has developed a superconducting material that retains this property up to temperatures of 300-400 celsius. I'd like to add some color around the effects of such an invention, but not being an engineer, I'm at a loss. The article on technological applications of superconductors has some ideas (like more efficient tokamaks, the main point of the story) but it seems like superconductors operating at true room temperature (and, as a premise, reasonably cheap to make) would have more applications than the power grid and maglev. For instance, couldn't you use them as part of a telecom network by adding phase variances to the power without disrupting the transformers on either side? It's my understanding that in a superconductor although the electrons themselves wouldn't necessarily move particularly fast the electric current would move at almost the speed of light so the power grid would double as a fiber-optic network. Just an idea, might be wrong; any other thoughts? 24.215.229.69 (talk) 22:59, 13 July 2011 (UTC)

Superfast computing? --Jayron32 23:06, 13 July 2011 (UTC)

Just don't repeat the sort-of error of Larry Niven's Known Space series: a superconductor is not necessarily a perfect heat conductor. Or so I've heard... Wnt (talk) 23:16, 13 July 2011 (UTC)

Of course, the idea behind fiction is "to make stuff up for entertainment purposes". Thus, the idea behind science-fiction is "to make stuff up about science for entertainment purposes". Also see Clarke's third law, which is intended to apply to science fiction. Science fiction generally fails when it gets too technical, since it invariably gets more wrong the more it tries to make itself sound like "real science". That's why Arthur Clarke wrote his third law; the idea is that you should just leave your advanced technologies somewhat "magical". Let the reader know enough about it to know that it does work, without trying to make the reader know how it works, since the how is almost always wrong. --Jayron32 23:24, 13 July 2011 (UTC)

Resistance is heat production, so presumably a room temperature superconductor could be cooled to slightly under room temperature and still be used to draw heat away from other components? I'm not sure what the point is either, to be honest. I'd rather have more efficient electrolysis anodes, if we're going to be searching the space of alloys. 99.24.223.58 (talk) 05:08, 14 July 2011 (UTC)

Cloud rays

Is there any name for the phenomenon when the corpuscular-like sun rays get the cloud's color (like the pink ones on the photo)?--Brandmeister t 23:17, 13 July 2011 (UTC)

Virga. --Jayron32 23:19, 13 July 2011 (UTC)

Thanx, updated the file info. Brandmeister t 23:29, 13 July 2011 (UTC)

Wait. That might not be right. Virga is rain that does't reach the surface. If it reaches the surface than it is called rain. Dauto (talk) 23:53, 13 July 2011 (UTC)

Dauto is correct. The image in question appears to feature two areas where precipitation is reaching all the way to the ground; these are called rain shafts (no article??). -RunningOnBrains^(talk) 00:12, 14 July 2011 (UTC)

Right, that's rain backlit by the sun. Note also that the premise of the question isn't right: sun rays don't get their color from clouds, rather the reverse. Looie496 (talk) 00:16, 14 July 2011 (UTC)

Strange, I thought they were rays, reverted. Apparently a file mover is needed then. Brandmeister t 00:37, 14 July 2011 (UTC)

I'm a filemover on Commons. What do you need it named to, "Backlit rain shafts"? --T H F S W (T · C · E) 17:32, 14 July 2011 (UTC)

Yep. Or something like that. Brandmeister t 11:07, 15 July 2011 (UTC)

Antimatter bomb

How big would the explosion be from annihilating 1 kg of antimatter with 1 kg of normal matter? --134.10.116.13 (talk) 23:45, 13 July 2011 (UTC)

See Mass–energy equivalence. Remember that mass is mass, regardless of whether it is matter or antimatter. Plug 2 kilograms into the equation for the mass, the speed of light for c, and you will get out the amount of energy. For explosive energy, the standard is to convert the joules of energy into a TNT equivalent. You can do that math pretty easily as well. --Jayron32 23:54, 13 July 2011 (UTC)

As for how big the explosion would be, that's a bit more complicated than finding the yeild. In space the size of the fireball would roughly vary with the cube root of the yeild. In a plane it would vary with the square root. So, you get something between those two with a surface explosion. StuRat (talk) 02:33, 14 July 2011 (UTC)

The size, in terms of volume, of the exlposion itself will also be highly dependent on the local atmospheric conditions; for example the density of the air, which is itself dependent on things like temperature, humidity, and barometric pressure, and may not be uniform over the course of the explosion, complicating matters. That's why it is much easier to speak of the "size" of an explosion in terms of energy content (which is how the strength of explosive materials is usually quoted, in TNT equivalents which I cited above) rather than in terms of volume. --Jayron32 04:28, 14 July 2011 (UTC)

July 14

Toilets

I was recently in Hanover, beautiful place btw, if you ever have the chance, but nevermind that, anyway, the private toilets are different. They have a kind of "platform" in the bowl that the, erm, solid releases, fall o, which does not have water, then there is a lower area in the back that the flush pushes it into that has water. Here in the states by contast the releases drop directly into the water, like a true bowl. The US toilets have the problem of excessive and uncomfortable splashing, but the German toilets have the problem of the odor of faeces not submerged. Is there a middle ground that solves the splashing problem without creating the odor problem? Thanks. 12.177.253.250 (talk) 00:19, 14 July 2011 (UTC)

There seem to be a wide variety of alternatives listed at Flush toilet#Bowl design, but it's hard to tell which have the best splashing versus odor trade off by looking at them. You might want to ask on a plumbing forum such as this one. 99.24.223.58 (talk) 00:48, 14 July 2011 (UTC)

Modern dual flush toilets from Australia would seem a sensible middle ground. Your personal output is quickly drowned, but much less water is consumed than in a typical American toilet. And less splashing. As an Australian visiting America it made me feel comfortably at home to find them at Grand Canyon Village, a town with water supply challenges. HiLo48 (talk) 06:56, 14 July 2011 (UTC)

Original research, but the low seat versions seem to be the best, as the drop is only a couple of inches. It just slides into the water rather than dropping. Also see Wikipedia:Reference_desk/Archives/Science/2009_March_16#German_toilet for more information on the German attitude.--Shantavira|^{feed me} 07:55, 14 July 2011 (UTC)

I came across this toilet design in Poland at my aunties house. After the 1st time I used it and made a mess I learned to lay a piece of toilet paper down 1st which greatly reduces the chance you'll need to clean up after. Vespine (talk) 23:16, 14 July 2011 (UTC)

German toilet currently redirects to the stub washout toilet (which is considerably smaller than the flush toilet#Washout toilet section). From reading elsewhere, I've understood that the primary motivation behind this design is to allow easier examination of the stool for hygienic and health purposes, a cultural practice. -- 203.82.93.119 (talk) 02:21, 15 July 2011 (UTC)

Neutrino

What's the mass of a neutrino? --134.10.113.106 (talk) 01:28, 14 July 2011 (UTC)

Read the article with the surprising title of neutrino which will answer your question, especially the section with the hard to understand title of "Mass". If you have any questions about what you read in that section, feel free to come back and ask them. --Jayron32 01:39, 14 July 2011 (UTC)

Or to put it in a less blunt way, we're volunteer human beings here, some of us quite busy with real lives. While I love answering questions for the curious, I don't like answering questions which would be easily answered by typing the word you're curious about into the Wikipedia search bar. I suggest you read neutrino; the answer may surprise you.-RunningOnBrains^(talk) 03:32, 14 July 2011 (UTC)

Please see Neutrino#Mass. 99.24.223.58 (talk) 04:59, 14 July 2011 (UTC)

It gives "masses" as eV, which aren't mass. --134.10.113.106 (talk) 06:54, 14 July 2011 (UTC)

Electronvolt#Mass suggests otherwise. Can someone confirm that 1 eV is 1.78*10^-33 grams? 99.24.223.58 (talk) 07:14, 14 July 2011 (UTC)

Strictly speaking an eV is a unit of energy, not mass. However, (as the eV article states) the mass-energy equivalence principle makes it equivalent to 1.78266173 * 10^{-33 grams [19]. -- CS Miller (talk) 08:38, 14 July 2011 (UTC)}

Breaking molecules

When you cut a piece of plastic, are you actually cutting through molecules, or just separating molecules from one another? What about other material such as wood? When water is smashed about like in a blender or a huge wave crashing, is there enough energy to break any water molecules apart? — Preceding unsigned comment added by 86.186.8.147 (talk) 02:29, 14 July 2011 (UTC)

You are seperating molecules from each other, not breaking intramolecular bonds. In general, intermolecular bonding is relatively weak, which is why you can seperate molecules from each other fairly easily. In substances which are not composed of discrete molecules, but rather consist of a massive network of nearly identical bonds, like titanium or sodium chloride or diamond, the material is actually quite hard to break. But for substances composed of molecules, it is usually fairly easy to seperate the molecules from each other, comparitively speaking. --Jayron32 02:32, 14 July 2011 (UTC)

Plastics vary by polymer length. If you cut some plastics with a power saw, they will ionize (you can often smell ionized plastics which smell like burnt plastic.) The same is true of wood, except that ionized wood smells more like burnt wood than burnt plastic. Water can not be ionized in a blender. Nor will ocean waves spontaneously ionize. 99.24.223.58 (talk) 04:51, 14 July 2011 (UTC)

Whether you are breaking molecules or not depends on molecule size. Water has very small molecules, so there is almost no way to break them apart by physical means (chemical or electrical means are all that can do it). With plastics, if the polymer is long enough, you will actually be breaking molecules apart (wood is made of cellulose, but I don't think the individual molecules are quite as long). --T H F S W (T · C · E) 17:28, 14 July 2011 (UTC)

Oppositional defiant disorder - Political abuse of psychiatry?

So a child's parents tell them to follow religious teachings, and the freethinking child disobeys parents, smoke pots and have sex, will they be diagnosed with Oppositional defiant disorder? Or all anarchists (including Noam Chomsky LOL), according to APA, are suffering from ODD? [20][21] Why APA is abusing psychiatry in Soviet-style? --111Engo (talk) 03:30, 14 July 2011 (UTC)

On a further research, I found this discussion. See the last post by Bruce A. Now I'm confused. Is it associated with children only, and the media misrepresenting the manual? --111Engo (talk) 03:39, 14 July 2011 (UTC)

Is this a question? Are we allowed to give more than one answer? AndyTheGrump (talk) 03:41, 14 July 2011 (UTC)

Well, you really shouldn't put much weight in Yahoo answers, and the manual in question certainly does not seem to support the claims made by the article to which you linked. In all instances they are (implicitly) describing children or adolescents being oppositional or defiant toward adults, and a person must meet at least four of the criteria, only two of which have to do with disobeying authority. They also state that the behavior must persist for "at least 6 months", and must present an "unwillingness to compromise", none of which seem to apply to civil disobedience. That is certainly not the meaning intended by the writers of this book (doctors are people too). They really should have included the phrase "routine requests", since the real manifestation of this disorder is supposed to be when a person will not comply with a simple request like "Sir, please put your pants back on. This is a family establishment." Of course, I think it's another buzzword term to excuse people for acting like assholes (read: overdiagnosis and self-diagnosis of ADHD and Aspberger's), but that's my personal (and, admittedly, only slightly educated) opinion. -RunningOnBrains^(talk) 04:00, 14 July 2011 (UTC)

I would indeed take such psychiatric practices with a huge grain of salt. It is not like the industry has a spotless track record! The criteria require that children who vehemently disagree with rules might be angry in two identifiable ways - which should scarcely seem a surprise under the circumstances. Psychiatry is a matter of people having problems and someone trying to fix them - where "having problems" means that someone doesn't act the way the person in a position to pay the bills wants. Wnt (talk) 04:37, 14 July 2011 (UTC)

To confront the "hidden question" in the OP's post, with many behavioral disorders, there is a modern trend towards overdiagnosis and medicalization. This does not mean that the disorder itself is not real, just that everyone who claims to have the disorder, or who are assigned the disorder by a medical professional, may not in fact have it. In other words, there are real people with real problems that may need real help. However, this is complicated by the fact that personality traits which are considered outside of the normally acceptable pallate of personality traits have themselves been confused with genuine behavioral disorders, and thus people, even well trained medical professionals, confuse when someone has a genuine need for medical intervention, versus where someone is just differently wired, but not in a manner which interfers with normal life. At one time, mental disorders which were treated medically were limited to serious psychoses like schizophrenia, but over recent history there has been a trend to treat what used to be considered as normal (if somewhat annoying in certain social situations) personality traits as disorders. --Jayron32 04:40, 14 July 2011 (UTC)

Hmmmm... how about female hysteria? According to the article it affected 25% of women, including symptoms like "irritability, loss of appetite for food or sex, and 'a tendency to cause trouble'". Sounds like a rather closely related condition, no? Wnt (talk) 04:52, 14 July 2011 (UTC)

That's sort of the point. There may have been real women with real psychological problems that needed real theraputic or medical intervention. But by overdiagnosing such a rediculous number of women, with perfectly normal personalities, as "hysterical", it both wasted the resources of the medical system and masked the real problems of the few real women who may have needed real help. A third problem is a sort of "backlash" against people who really have mental disorders, since the public has become quite aware of overmedicalization. For example, some kids really do have ADHD. But so many kids that don't have it are mistakenly diagnosed with it that people believe that the disorder doesn't really exist, and that the label is just an excuse for parents to drug their children and keep them compliant. The kids that really do need drugs to manage their disorder thus get stygmatized as "not having a real disorder" when they actually do, because all of the kids that actually don't have it give everyone else a bad name. Again, I am not in full agreement with the OP here, in the sense that I recognize that behavioral disorders of all types do exist, but the tendency to make every socially inconvenient personality trait one of these disorders does a disservice to literally everyone involved. To the OP's point, there really are people who have a mental disorder that makes them violent and unmanagable in the face of authority, to the point where they need genuine theraputic and/or medical help. That we confuse these people with genuine mental problems, with other people who have healthy brains but choose to be nonconformists, is the real problem. Its not the non-existance of the disorders, its the overassigning of the disorder to people that don't have it, that is the problem. --Jayron32 05:05, 14 July 2011 (UTC)

Do you mean: 1. behavioral disorders of all types that actually exist do exist, 2. behavioral disorders of all types ever thought to exist do exist, or 3. behavioral disorders of all types currently thought to exist do exist? (Excuse me if this question seems confrontational, I'm probably exhibiting challenging behaviour.)  Card Zero  (talk) 09:28, 15 July 2011 (UTC)

Are you asking whether it will be easy for religious parents to find psychologists predisposed to their opinions in order to lock up or drug children who don't believe their superstitions? Or suggesting that we must all ask our local psychological licensing authorities how they would protect against such a situation? Or are you a victim of vindictive religious parents who have tried to have you locked up or drugged? Or are you a religious parent seeking to lock up or drug a freethinking child? Context is important here. 99.24.223.58 (talk) 04:58, 14 July 2011 (UTC)

Yeah, context is important ... it's important so some holier-than-thou people of a non-religious sort can lecture the questioners and answerers about the "unethical" and contrapolicy nature of "giving medical advice". Wnt (talk) 05:15, 14 July 2011 (UTC)

The direct answer to the OP's question is that this diagnosis is only applied to children, so describing it as a Soviet-style abuse of psychiatry is off the mark. Looie496 (talk) 05:14, 14 July 2011 (UTC)

Similarly, the governmental system in Cuba in the 1960s wasn't Soviet-style, because it only applied to Cubans.  Card Zero  (talk) 09:19, 15 July 2011 (UTC)

If you have ever met an ODD child or known people that work with them regularly, you immediately know the difference between a child that has a behavior problem and one with a conduct disorder. ODD is a true mental disorder, meaning it is not rational or in many cases controllable. An ODD child could be told not to do something they don't even WANT to do, but they would do it just because they are told not to. They are some of the more sadistic people you'll ever meet, they will do things just to be contrary or as annoying as possible. ODD is a conduct disorder with all that implies, including being a potential pre-requisite to a diagnosis as an adult of antisocial personality disorder, also called Sociopathy. There's a big difference between a poorly behaved child and a potential sociopath-in-the-making. HominidMachinae (talk) 08:32, 14 July 2011 (UTC)

Severe weather warning beeps on radio

The local radio stations in Salina, Kansas owned by Morris Communications ([22]) will sometimes, when there is a severe thunderstorm warning or tornado watch/warning affecting their listening area but when they are not in continuous severe weather coverage, turn on some system that inserts a particular beeping sound once every couple minutes (more than just a simple beep...I believe the best way to describe it is a set three higher beeps followed immediately by three slightly lower beeps lasting about one second total, repeated after a little less than one second for a total duration of about three seconds). While touring the radio stations' facilities a few years ago I caught a glimpse of the hardware used to insert these beeps into the broadcast audio (fittingly labeled "SEVERE WX BEEP GENERATOR"). I went looking for information on such equipment today, but I can't seem to find anything about them using Google, despite the fact that I'm fairly certain other radio stations use variations of them (with different sounding/patterns of beeps) as well. What exactly are these severe weather beep generators and where can I find information on them? Ks0stm ^(T•C•G) 05:15, 14 July 2011 (UTC)

I believe that the article Emergency Alert System will answer many of your questions. It even has pictures of some of the equipment used, which may be exactly what you are looking for. I also see bluelinks to more specific articles on the equipment. --Jayron32 05:28, 14 July 2011 (UTC)

Actually, it wasn't EAS related...this is some system that they manually turn on when there are the severe weather alerts I mentioned in effect for their listening area and that remains on, producing the beeps, until the severe weather alert has expired or been cancelled, at which time they switch it off. The only EAS broadcasting that these stations do are EAS weekly/monthly tests. Ks0stm ^(T•C•G) 05:34, 14 July 2011 (UTC)

Ah. In that case, you seem to be looking for some sort of tone generator or Signal generator. There are hundreds of these things out there. The section titled "Pitch generators and audio generators" has a little bit on them, but not on any specific models. --Jayron32 05:40, 14 July 2011 (UTC)

Planck unit for luminosity

Does a Planck unit exist for luminosity and if so, what is it in terms of candelas? Widener (talk) 07:24, 14 July 2011 (UTC) Oh and if it happens to be a derived Planck unit, I would also like to know what it is expressed in terms of the fundamental Planck units. Widener (talk) 07:42, 14 July 2011 (UTC)

Planck power, but I can't convert because candelas are apparent luminosity instead of bolometric. 99.24.223.58 (talk) 07:47, 14 July 2011 (UTC)

Exactly right. luminosity really isn't a physical quantity and candelas really aren't a physical unit so a Planck unit for them is meaningless. Dauto (talk) 13:46, 14 July 2011 (UTC)

Correcting what I said above. I meant to say Luminous intensity isn't a physical quantity (That's the one measured in candelas). There is nothing wrong or un-physical about luminosity which is measured in Watts. Dauto (talk) 15:27, 14 July 2011 (UTC)

I suppose luminous intensity (apparent luminosity) is a real physical quantity based on radiation in the visible spectrum. But x Watts of white light is still x Watts. As a practical matter, for quantities that large, there is really no way to assume that much power would be measurable because it would ionize any observer or measurement apparatus. [23] has some details that might help. 99.24.223.58 (talk) 22:07, 14 July 2011 (UTC)

Luminous intensity depends on the physiological response of the human eye. That means it is not a "pure" physical quantity. Dauto (talk) 00:27, 15 July 2011 (UTC)

We would have to know the shape of that response curve (for three kinds of cone spectra, maybe we can use a normal distribution to approximate) to get the ratio between uniform spectrum wattage and white light wattage. Then we would be able to answer this. Sorry, that wouldn't help either, because the integral of +1 over [0, +infinity) for a uniform spectrum is probably undefined, or if it's not it should be in this case. Thank you. 99.24.223.58 (talk) 22:29, 15 July 2011 (UTC)

Question about animal blood analysis .

Italic text I want to know what are the normal medical values for a hematology tests

in dogs. Thank you in advance . 95.107.197.63 (talk) 09:09, 14 July 2011 (UTC)

Does this website help? canine bloodwork Zzubnik (talk) 10:42, 14 July 2011 (UTC)

Exotic matter

Is it possible to create a liquid phase consisting entirely of protons confined in a Penning trap? If it is, and assuming that does not exist at STP, what is the pressure equivalent of the boiling point at 1 nK? Plasmic Physics (talk) 10:35, 14 July 2011 (UTC)

No, liquid implies contact, and the coulomb barrier for that compression seems to be greater than could realistically be expected to be applied from external sources. Consider the power required to simply keep two protons in contact. 99.24.223.58 (talk) 10:51, 14 July 2011 (UTC)

OK, but what about extraordinary conditions like in special types of stars, where protons are crushed together? Then again that's not really a liquid, it's more like a supersolid. Plasmic Physics (talk) 11:41, 14 July 2011 (UTC)

Neutron stars exist because they are composed of neutrons, which are neutral and thus not all that repuslive. The repulsive forces involved in condensed protonic matter may be hypothetically calculatable, but likely the result would be so huge to be meaningless. --Jayron32 11:56, 14 July 2011 (UTC)

Agreed - I think we are talking about degenerate matter here, but I don't see how that can be constructed just from protons alone. Nearest equivalent is metallic hydrogen, which, in its solid form, is a lattice of protons surrounded by a sea of unbound electrons. Gandalf61 (talk) 12:06, 14 July 2011 (UTC)

It strikes me that if you beam pure protons straight into a black hole, it nonetheless will not achieve infinite charge, because the Hawking radiation will become biased. Is it possible to calculate a maximum possible charge density for a black hole? Is that the upper limit for concentration of charge in that volume of space, regardless of the nature of the containing force? Wnt (talk) 17:28, 14 July 2011 (UTC)

Does the article Charged black hole lead you to some solutions to your problem? --Jayron32 18:02, 14 July 2011 (UTC)

(EC) You are probably right about charged black holes having a limit as to how much charge they can have. According to the cosmic censorship hypothesis, non-rotating charged black holes with r_Q > r_s/2 in the Reissner–Nordström metric, where r_Q is a radial measure proportional to the black hole's charge and r_s is the black hole's Schwarzschild radius, do not exist in nature, because that would result in a naked singularity. Red Act (talk) 18:07, 14 July 2011 (UTC)

I would have preferred a derivation based on the impossibility of shooting the particle into the field because (for example) virtual pairs would be sure to interact with it and spirit the charge away - rather than an unproved ban on singularities in free space - but it does give a ready number. The article says that

$r_{Q}^{2}={\frac {Q^{2}G}{4\pi \epsilon _{0}c^{4}}}$

and the total radius r_S in which the charge is confined is simply 2r_Q. Thus Q <= (r_S/2)(c²)sqrt(4πε₀/G) = sqrt(3.1415927 * 8.85418782×10⁻¹² F·m⁻¹ / 6.6738480×10⁻¹¹ m³ kg^-1s^-2) (299792458 m/s)² r_S

= sqrt (0.416794806 s⁴·A²·m^-2·kg^-1·m⁻⁴ kg¹s²) (8.98755179 × 10¹⁶ m² s^-2 r_S

= 5.80233174 × 10¹⁶ C/m r_S. Unless I fouled up... Wnt (talk) 18:56, 14 July 2011 (UTC)

N.B. one actual unit of charge, (1 / 6.24150965(16)×10¹⁸) C, should then be confined to occupy at least rS = (1 / 5.80233174 × 10¹⁶) m/C (1 / 6.24150965(16)×10¹⁸) C = 2.76126316 × 10^-36 m or 1/5.85 of the Planck length. Odd... Wnt (talk) 19:10, 14 July 2011 (UTC)

What's odd about that? Dauto (talk) 19:44, 14 July 2011 (UTC)

Well, the Planck length is special in terms of when the Compton wavelength of a black hole just barely fits inside the Schwartzschild radius, but I haven't heard of a similar fundamental role in defining charge. If 5.85 were some simple/predictable number, it would mean the various fundamental constants described above could be defined in terms of one another - one less fundamental constant. Hmmm, this r_S takes up a volume of (4/3)* pi * r_S³ = (4/3) * 3.1415927 * ℓ_P³/(5.85330958³) = 0.0208873879 ℓ_P³ or (0.275398378 ℓ_P)³ = (1.73037906 *2pi*ℓ_P)³ Now the square root of 3 is 1.73205081, about 1/1000 too high ... that's too far off, and just coincidence ... isn't it? (I really didn't try a lot of numerology here, and after coming up with that bothered to read that Planck length is already based on hbar, and proportional to the square root, yet... yeah, I think I crossed into crankdom at that point. Still don't know where 5.85 came from.) Wnt (talk) 22:56, 14 July 2011 (UTC)

What you did was calculate $2\alpha ^{\frac {1}{2}},$ where $\alpha \,$ is the fine structure constant.

$r_{e}^{2}={\frac {e^{2}G}{4\pi \epsilon _{0}c^{4}}}=\alpha l_{P}^{2}$

Dauto (talk) 23:31, 14 July 2011 (UTC)

How are charged black holes related to my scenario? Plasmic Physics (talk) 02:55, 15 July 2011 (UTC)

They are not, except for the fact that they are ways to pack positive charged particles. Dauto (talk) 15:04, 15 July 2011 (UTC)

July 15

mental retardation questions

Are autstic people retarded? Are people with cerebral palsy retarded? Are people with brain damage retarded? I know that retardation is a real term, not just offensive slang, so this is why I ask this type of question.--68.197.153.156 (talk) 01:04, 15 July 2011 (UTC)

Mental retardation is typically a measure of IQ. Any number of conditions can lead someone to have such a low IQ that they are considered clinically mentally retarded. Very severe autism, brain damage, and cerebral palsy can cause mental retardation, but one could not say as a rule that all autistic, etc. people are mentally retarded — many are not. Many autistic people, for example, have extremely high IQs; many people with brain damage do not have their IQ affected. --Mr.98 (talk) 01:14, 15 July 2011 (UTC)

Also, the term "mental retardation" is falling out of favor in the medical community, in favor of the terms "intellectual disability" or "physical disability". I don't get the change personally, probably political correctness, but the definitions should be the same. -RunningOnBrains^(talk) 01:53, 15 July 2011 (UTC)

Perhaps an example of the euphemism treadmill. AndrewWTaylor (talk) 07:52, 15 July 2011 (UTC)

The problem with the question when applied to autism is "what do you mean by retarded?" It's not just political correctness, its a lack of specific meaning. By the dictionary defintion of retarded it implies that mental development is a linear process and that for some it stops early. Like "his mental age was that of a four year old". But normal kids are not simultaneously capable of extreme concentration on a topic and unable to interprete body language. Normal kids are potty trained before they learn to read. The concept of "mental age" doesn't work. When you consider people with different disabilities, you find that a label like "retarded" is useless. Whether your goal is to treat the condition, accomodate the person better or just know what to expect in terms of behaviour, you can't avoid drilling down to the specifics. Autism in particular, is over such a wide spectrum that you can't avoid dealing with individuals. EverGreg (talk) 08:50, 15 July 2011 (UTC)

The OP says retardation is a real term. I'd be interested to know what the OP thinks it means. Literally it seems to imply something parallel to what is sometimes called slow development. That's not the same thing as low IQ. Another problem with these terms is that usage varies dramatically around the world. I don't know where the OP is from. I know a lot of people with cerebral palsy. Very few have low IQ. Many are insultingly called retarded at times. It's a minefield. Unhelpful word. HiLo48 (talk) 08:57, 15 July 2011 (UTC)

It's not just a euphemism (as EverGreg pointed out). Many people lack or are deficient in the ability to accquire specific skills - theory of mind, reading body languague, understanding grammar etc. "retardation" is not accurate and does not help in understanding the condition. With regard to brain damage, people can lose many different faculties- they my develop emotional disorders: inability to concentrate or mood swings(for eg frontl damage), Difficulty in forming or recalling memories, languague deficits (either speaking or comprehending), Arithmetic(yes lose the ability to do arithmetic without losing the idea of numbers, its true), etc while retaining all of their other faculties. Depending on the severity and the type of disabilities present, patients are classified as intelectually disabled. — Preceding unsigned comment added by Staticd (talk • contribs) 09:14, 15 July 2011 (UTC) Staticd (talk) 09:15, 15 July 2011 (UTC)

On heat flow.

I recently read a post on a forum which stated the following:

"Heat is the flow of thermal energy from one body to another. Objects feel hot or cold depending on how fast heat is transferring between the objects. The rate of heat flow is determined by both the temperature difference and the thermal conductivity between the two objects. For example, touching a steel pole at 32 F will feel colder than a wooden pole at 32F."

I'm inclined to believe that this is a false statement but, who knows? So... errr... Is it true? — Preceding unsigned comment added by 186.29.119.171 (talk) 01:20, 15 July 2011 (UTC)

Yes, it is true. Dauto (talk) 01:40, 15 July 2011 (UTC)

This is the reference desk, not the yes man desk. Not only are the statements true, there are relevant articles: Heat, Specific heat. μηδείς (talk) 01:43, 15 July 2011 (UTC)

It was just answering the question, Jeesh...Heat conduction is another useful link. Dauto (talk) 01:54, 15 July 2011 (UTC)

Umm, can I ask anyone to expand on the reason of why the steel pole would feel colder than the wood pole at the same temperature? — Preceding unsigned comment added by 186.29.119.171 (talk) 02:02, 15 July 2011 (UTC)

I think it is related same reason a thermos or styrofoam cup keeps your coffee hot longer than a metal cup would on a cold day. It is the same reason why we make cookware out of cast iron and cooper but never wood (also because the wood would probably catch on fire, ha ha). It is the same reason we make mittens out of wool, not out of aluminum. Because some things are better conductors of heat and electricity, while other things are better insulators.--Fran Cranley (talk) 02:07, 15 July 2011 (UTC)

To put it another way, the steel pole has more specific heat capacity to cool your skin's nerve ending's much faster than the wood. 99.24.223.58 (talk) 04:54, 15 July 2011 (UTC)

Not exactly. This has nothing to do with specific heat, and everything to do with thermal conductivity. Specific heat capacity of steel is actually much lower than that of wood. Specific heat capacity refers to a substance's "temperature/energy" relationship; that is the amount of energy contained in a given mass of the substance at a certain temperature. Steel's lower specific heat means that it will gain more degrees of temperature with an equivalent amount of energy than wood will; however the key factor missing in determining why the steel feels colder is the time factor. Steel feels colder, despite having a lower specific heat, because it the heat it does conduct away from your skin is conducted away on a faster time scale than the wood does. In other words, I can get 1 joule of energy out of my skin in less time when it touches steel than when it touches wood. Ultimately, the wood's temperature will go up less than the steel's temperature will once they both have absorbed that 1 joule of energy from my skin, but the difference in sensation has less to do with the final temperature than with the speed at which that joule of energy is extracted from my skin. --Jayron32 05:18, 15 July 2011 (UTC)

Both. Thank you. 99.24.223.58 (talk) 22:20, 15 July 2011 (UTC)

Let me give it a shot too. Your perception of hot or cold comes from the temperature of the thermosensitive nerves just under your skin. They are being heated to by blood behind them and they are being cooled from the front by the thing you are touching. Depending on the rate at which the cooling occurs( i.e the conductivity of the object) the "heat" gets "dammed up" to different levels and the skin reaches different equillibrium temperatures.

This is somewhat analogous to the rise in water near your foot when you step into a stream: the height reached depends on the rate flow of water and the resistance. (both follow approximately dQ/dt=KdT/dx and dV/dt=Kdh/dt)Staticd (talk) 07:11, 15 July 2011 (UTC)

MOST LIKELY AVENUE

PRECEDING REMOVED. WIKIPEDIA I REALIZE VERILY WELL THAT THERE MIGHT NOT BE "1" ANSWER. I WOULD LIKE TO KNOW, IF HUMANITY WERE, THIS IS TO SPEAK HYPOTHETICALLY, MODIFY ITS OWN GENOME: 1. WHAT IS THE MOST LIKELY TIMING AND LOCATION THIS WILL HAPPEN? (RESEARCH UNIVERSITY, GOVERNMENT PROGRAM, INDUSTRY, STARTUP, ETC). 2. WHAT IS THE "MOST LIKELY" AVENUE TO PREVENT THIS. THANK YOU. I AM HAPPY TO READ REFERENCES. 188.222.102.201 (talk) 02:00, 15 July 2011 (UTC)

NOTE, I MEAN FULL BRED MODIFIED GENOME. REAL HUMANS FROM GENETICALLY MODIFIED HUMAN DNA. ALSO, THERE IS A THIRD PART OF MY QUESTION: IS THERE ANY INDICATION WHATSOEVER (AGAIN, REFERENCES PLEASE) THAT THIS HAS ALREADY BEEN DONE, GIVEN THAT CROPS ARE MODIFIED WITH IMPUGNITY ALL THE TIME THANK YOU--188.222.102.201 (talk) 02:01, 15 July 2011 (UTC)

I think there is probably not a better answer than to point you to our article on human genetic engineering. (Please don't write in all-capital-letters -- it comes across as shouting.) Looie496 (talk) 02:06, 15 July 2011 (UTC)

The laws forbidding interracial marriage were a recent attempt to modify the human genome. 99.24.223.58 (talk) 04:57, 15 July 2011 (UTC)

I'd say it's already happening, but in tiny steps. First we've seen gene therapy to remove, repair, or deactivate defective genes which cause diseases. Next perhaps will be some simple cosmetic changes, like eye color. Then we might get into more substantial changes, like height. From their we might start tinkering with emotions and intelligence. StuRat (talk) 06:53, 15 July 2011 (UTC)

Matter acceleration to speed of light...?

Yes, I understand that special relativity states that no particle with non-zero rest mass may ever reach the exact speed of light because its mass would approach infinity as it would get closer, which would imply infinite energy and bla, bla, bla. But, this same theory also predicts that matter and energy (which can accelerate to that speed) are the same entity, bringing me to my question.

Why is it, exactly, that matter cannot travel at the speed of light, whereas energy, which is theoretically the same entity as matter, can?186.29.119.171 (talk) 02:42, 15 July 2011 (UTC)

Photons are massless particles, and as such, must move at the speed of light (being, in fact, the embodiment of light). Anything with mass would require an infinite input of energy, as you note. Neutrinos are nearly massless, and move at nearly the speed of light. Acroterion (talk) 03:05, 15 July 2011 (UTC)

That is exactly kind of answer I was trying to avoid... Let me re-phrase, then. Fundamentally, what makes matter different from energy so that it may not travel at the speed of light? I mean, I perfectly understand the basic principles of both special and general relativity, but I just have to wonder why this happens, if they're supposedly the same entity.186.29.119.171 (talk) 03:18, 15 July 2011 (UTC)

Don't think of "matter" as being different than "energy", because you are really comparing apples and oranges. It's like saying "Why is apple different than color". Color is a property that an apple has, while apples have other properties as well, like texture, taste, size, etc. etc. Matter has many properties, like charge, spin, momentum, volume, and "mass" is but one of the properties of matter. Mass and energy are the same thing, the distinction in names is partly historical, and partly to distinguish between "potential energy that is tied up within a substance" (which is all mass is) and "kinetic energy that is moving an object around", which is what we usually think of when we call something "energy". One of the "defining" characteristics of "matter" is that it has a mass, which is another way of saying that it has the ability to trap and hold onto energy indefinitely; particles like "photons" that have "no rest mass" basically just means that photons have no internal potential energy of their own, and exist solely as vehicles to carry kinetic energy. So remember, matter and energy isn't the same thing, it's "mass" and energy that is the same thing. As far as why matter has the mass form of energy, that is the $64,000 question in physics today. The most accepted hypothesis of the source of mass is the Higgs mechanism, but as yet experimental proof, in the form of positive confirmation of the Higgs boson, eludes physics. If you want to think in very lay man's terms (and that's all I am capable of thinking in anyways) the Higgs mechanism is a way of explaining how energy became trapped in matter in the first place, providing matter with "mass". --Jayron32 04:30, 15 July 2011 (UTC)

Another source of confusion is the incorrect belief that light is the same thing as energy, or that is "pure" energy. Dauto (talk) 12:33, 15 July 2011 (UTC)

Exactly, energy is a property of light, just as mass is a property of matter. But it is not identical to it. Light has other properties; unrelated to its energy content. Light, for example, also displayed properties like polarizability and photons themselves have spin which is unconnected to their energy content. --Jayron32 14:56, 15 July 2011 (UTC)

I think I understand the question being asked, and am not sure that it has been directly answered. Let's say we have a photon of a certain energy. By E=mc^2, can we not say that that photon is equivalent to a small but finite mass? And if so, how could it have infinite speed? I think the proper answer should be that the photon is equivalent to a certain rest mass, and that the problem arises when you unconsciously smuggle back in the velocity. You have forgotten that if E=mc^2 then m equals not E alone but m=E/c^2 and the velocity has been divided out. The photon is only equivalent to a small but finite rest mass which is at rest To speak of a rest mass not at rest is to introduce a contradiction. μηδείς (talk) 20:14, 15 July 2011 (UTC)

I think the question is a good one and it has an interesting answer in the Standard Model of particle physics. In the Standard Model, everything in the world (except gravity) is described by what amounts to a more complicated version of the electromagnetic field. It's a quantum field, but you don't need to understand the quantum aspect to understand the origin of mass.

Start with the electromagnetic field. You probably know that electromagnetic waves (light) can be polarized. You can describe any polarization state as a combination of two "basis states". For example, if you take horizontal and vertical polarization as your basis states, diagonal polarization is a combination of the two—simultaneous oscillation up-down and left-right—and circular polarization is also a combination, but with the horizontal oscillation offset in time from the vertical by a quarter period (as shown here).

There are exactly two circular polarization states: one rotating clockwise when viewed from behind and one rotating counterclockwise. These two states also work as a basis for all polarizations, and there's something special about them: they are "the same for all observers". Horizontal polarization turns into vertical polarization if you rotate your frame of reference, but clockwise circular stays clockwise circular when rotated, and also when you change the speed of the reference frame. This means that the electromagnetic field can be decomposed into two independent fields, one purely counterclockwise ("left handed") and one purely clockwise ("right handed"), in an observer-independent way. In theory, one could exist without the other.

The electromagnetic field is called a massless field because it has a certain natural correspondence with a theory of massless particles moving at the speed of light. If you write down the equations for a field with a nonzero rest mass m, it turns out to correspond to left-handed and right-handed fields that are coupled together with a coupling strength proportional to m². (If m=0 then the coupling is zero and the polarized fields are independent, as above.) Coupling means that a vibration in one field induces a vibration in the other. You can (if you like) think of independent fields as independent pendulums, and coupled fields as pendulums connected by a spring whose spring constant is the coupling strength (m²).

So a massive particle/field is two massless particles/fields of opposite circular polarization coupled together. You can think of this in the following way: all particles move at the speed of light. But massive particles sometimes change into particles of the opposite handedness. They retain their angular momentum; because of the opposite handedness, that means they reverse direction. So slower-than-light motion is back-and-forth motion at the speed of light. Your average speed can be zero even if your instantaneous speed at every instant is c.

In the Standard Model, all of the fundamental fermion fields exist in only one handedness. There's no direct coupling to mirror-image fields because there aren't any. Instead, there are more complicated couplings involving pairs of fermion fields (that have opposite handedness, but aren't mirror images) and the Higgs field. So it's not quite right to say that the Higgs field gives mass to particles—without the Higgs interaction, you don't have massless electrons and quarks so much as you have a bunch of one-handed massless fields that don't pair up in any natural way. Before the discovery of neutrino mass, it was thought that there simply is no "right-handed neutrino field", that is, no field that could be Higgs-coupled to the left-handed neutrino field without violating conservation laws. So neutrinos were purely left-handed and also massless—those two things go together. -- BenRG (talk) 22:38, 15 July 2011 (UTC)

Evolution reloaded

I saw the question titled Evolution a few days ago. While evolution has by no means stopped in general, I think it is relatively accurate to say that humans are no longer affected by Darwinian natural selection nearly to the degree that the natural world is. With modern medicine, no matter how maladaptive mutations are, the sufferers can oftne be kept alive long enough to propagate it to offspring (if it is propagable) and non-genetic diseases that would not have nearly the widespreadness that they do owe their success to modern medicine again keeping people alive and able to infect others (ie, AIDS). Moreover, the development of civilization and trade has made gradual adaptations for changing food availability almost obsolete. (Nowadays it seems that the natural next step of human evolution will be to propagate genes for promiscuity and hyperfecundity) QUestion: About when (I'm looking for a range, not a specific event) did humans stop being as affected by evolution? grazie. — Preceding unsigned comment added by 24.92.88.206 (talk) 03:17, 15 July 2011 (UTC)

That is completely not true either. There is no evidence that humans have stopped being "affected by Darwinian natural selection". That stance implies two spheres of existance, the natural, and the human, and somehow would imply that different sets of rules existed for human life than exist for "natural" life. Its a popular sentiment, which has a long history, and which I should note has no basis in science. Humans are under the same sorts of evolutionary pressures that all life forms are, and our genetic make up is open to the same sorts of changes as any life. Why must modern medicine be viewed as counter to evolution or something likely to "stop" it, rather than broadly as just another adaptation that the human animal has developed to adapt to its environment. It really isn't any different than any other trait in that regard. Humans are continuing to change, genetically, and will continue to do so for the forseeable future, on an evolutionary time scale. Our adaptations may change how our genes are passed on, and the rates at which changes happen, but really that isn't a uniquely human situation, every life form has adaptations which allow it to stabilize its gene pool for a time being; it's why we have distinct species with any history of stable phenotypes at all. Seriously, humans are not distinct from nature, and evolution has not stopped for us. As long as we keep having sex, and having children, we will keep evolving. --Jayron32 03:41, 15 July 2011 (UTC)

I completely agree with the above. I would just like to add that I think this misconception might stem, in some cases, with our human inability to conceptualize the sheer time scales that are involved in evolution. Estimates for the emergence of our species are at around one or two HUNDRED THOUSAND years, and we aren't a particularly old species at all. That means if you travelled back in time 100 or 200 thousand years, humans would have been pretty much exactly the same, enough that you could have viable offspring with them. It might be more valid to ask a crocodile the question of their species since fossil ancestors up to 84 million years old don't seem to be any different then crocodiles alive today. Vespine (talk) 04:22, 15 July 2011 (UTC)

Modern medicine is also extremely young - Semmelweiss introduced hand-washing around1850, and Pasteur worked in the 1860s. The pill was introduced 100 years later. And of course, only a very small part of the human population has access to most of modern medical technology. But that is not the core of the issue - the core is that we do not eliminate selection pressure, we just change it. --Stephan Schulz (talk) 06:10, 15 July 2011 (UTC)

Even assuming perfect healthcare, there are so many factors affecting the chances of survival and reproduction in modern society that natural selection is still central to human evolution. That is, human evolution is not dominated by genetic drift. Genes affect obesity, genes affect your behaviour, genes affect the chances of addiction, how you respond to medication, the chances of conceiving a baby and your ability to care for it. And if any of the preceding is not true, evolution could produce a new gene that does affect that trait, improving the person's fitness. In fact, human evolution has been shown to have sped up since the stone age, due to new ways of living, more diseases and new food. Some evolutionary theorists also predict that modern society, where people can take on more specialized tasks and be better cared for by healtcare, will speed up human evolution even more. The parallel pointed to is the wolf, which has been unchanged for many thousands of years and well adapted. But when the wolf was domesticated, it was freed of the evolutionary pressure in the forest, exposed to new evolutionary pressures and hence diversified into numerous types of dogs in the blink of an eye, evolutionary speaking. Far from being unaffected by evolution, humanity is being carried on a roaring wave of evolutionary change. EverGreg (talk) 08:31, 15 July 2011 (UTC)

The main thing that very recently changed is survival rate to adulthood. If this is maintained for a couple of hundred thousand years (and I am not saying I think it will be maintained, it very well may be a 200 year temporary anomaly), we may see a significant shift in human evolution towards sexual selection being the only trigger for evolutionary change, rather than a combination of natural selection, sexual selection and other things that are happening in the wild. --Lgriot (talk) 08:50, 15 July 2011 (UTC)

With our technology humans do not necessarily need to undergo physical change to adapt to different environmental pressures such as becoming more hairy in colder climates. We have developed the ability to modify our environment to suit our physical characteristics - clothing, shelter, furnaces, air conditioning, etc. This has to a significant extent eliminated much of the pressure driving physical evolution. Much of human evolution in the last hundred-thousand years or so has been behavioral rather than anatomical or physiological. Notable exceptions are traits such as the survival of lactase in adults in populations that use animal milk in their diet beyond infancy. Roger (talk) 09:14, 15 July 2011 (UTC)

Diseases such as alcoholism, other addictions, flu, other pathogens, etc. are still selecting us. In some areas, yes, we're under less selection pressure. Imagine Reason (talk) 13:11, 15 July 2011 (UTC)

Doing fine with 10,000 IU/day of vitamin D

Half a year ago, some people here suggested that taking 10,000 IU/day of vitamin D is dangerous, See here

I think most experts would say something like: "10,000(0) IU/day is probably safe for most people", but perhaps Count Iblis will let us know in a few years whether he has suffered benefit or harm from this dosage. Personally, I would prefer to err on the lower side in the absence of regular medical monitoring. If I had some 50,000(0) IU tablets, and wanted to use myself as a guinea pig, I would cut them in half and take half every three days, but please don't take this as medical advice because I have no medical expertise. Dbfirs 21:26, 21 December 2010 (UTC)

He won't be able to let us know as he will be dead or disabled. 92.15.26.185 (talk) 16:26, 22 December 2010 (UTC)

While this discussion happened half a year ago, I've been taking roughly 10,000 IU/day for almost two years now (I estimate how much I get from the Sun and then I supplement that to 10,000 IU/day). The year before that I took 5,000 IU/day. Now, I'm doing fine but obviously that's not proof that this is due to Vitamin D. It does show that vitamin D at a dose of 10,000 IU/day is not going to cause people to suddenly drop dead after a year or so as was sugested in that thread.

Some rough figures about my fitness levels: I used to work out 3 times per week before 2008. I would run at moderate to high speed for 20 minutes. My resting heart rate was in the mid 40s, often it would be close to 50. I had tried but failed to increase my fitness by attempting to gradually train a lot harder. It just didn't work out well. So, I wasn't very fit and I had difficulties improving my fitness.

Around 2008, when I started to take high dose vitamin D, gradually increasing exercise intensity and frequency did work. Today, I exercise 5 times per week, I do 35 to 40 minutes of fast running. My resting heart rate is usually between 37 and 40 bpm. Heart rate recovery rate after 35 minutes of running is typically 40 bpm/minute (heart rate drops from 160 bpm to 120 bpm in one minute). When I measure this at the start of the exercise, I find larger values, typically 60 bpm/minute.

Clearly, this is a huge increase in fitness. While it isn't proof that vitamin D has anything to do with this, it does make it unlikely that Vitamin D is interfering with vital body functions in a negative way. That it may help boost athletic performance is consistent with these findings.

Now, from the literature, we can get some clues that 10,000 IU/day is what one needs for optimal health. In this article, you can deduce from the relation between vitamin D dose and increase in calcidiol concentration, that the half life of calcidiol is not constant, it depends on the calcidiol level until you reach values of about 200 nmol/l. This means that vitamin D use by many cells is turned off below this level, the lower it is the less your body uses vitamin D. At low levels your body only uses vitamin D for calcium metabolism. This then suggest that even people with values as high as 150 nmol/l should be considered to be vitamin D deficient.

Then, in this article, we can read that breast milk does contain enough vitamin D for babies, but only if the mother takes about 6,000 IU/day of vitamin D. At lower doses e.g. 2,000 IU/day for the mother, the breast milk does not contain the known minimum amount babies need (400 IU/litre). So, the fact that we routinely give babies vitamin D supplements because "breast milk does not contain nearly enough vitamin D", should be a red flag that something is deeply wrong with current medical practices/thinking.

We don't need to dig deep to find the source of the problems. The reason why almost all pregnant women are severely vitamin D deficient can be found here:

"Vitamin D supplementation during pregnancy remains controversial largely due to severe misconceptions about the potential harm it may cause to the fetus,” said Dr Hollis. “Surprisingly the scientific debate has made little progress since Dr. Gilbert Forbes made a recommendation of 200 IU (international units) per day in 1963, which was based on a hunch.”

This flawed recommendation made it difficult to conduct studies to determine the correct level, because the correct level is so much higher than what was thought to be toxic. It has now been found that:

"In our study subjects, a daily dosage of up to 4,000 IU of vitamin D was required to sustain normal metabolism in pregnant women,” concluded Dr Hollis. “Furthermore, following decades of speculation into its safety our research has demonstrated vitamin D supplementation to be both safe and effective.”

Then another piece of flawed research led to the 2,000 IU/day UL. We can read here that:

95 µg (3800 IU) vitamin D3/d This clinical trial, conducted by Narang et al (14), involved 30 healthy adults divided among treatment doses of 10, 20, 30, 60, and 95 µg vitamin D3/d. No adverse clinical effects were reported, but the highest intake produced a significant increase in serum calcium to 2.83 mmol/L, a concentration slightly above the reported upper normal level of 2.75 mmol/L. Serum 25(OH)D was not measured. These results are very different from those in later studies that used higher doses given to larger cohorts and for longer durations. Thus, these results are inconsistent and conflict with the preponderance of the clinical trial database for high-dose vitamin D and therefore are not considered to credibly contradict the 250 µg NOAEL.

So, dead wrong, but still used as the standard to this day by many national medical institutions to set the UL at 2,000 IU/day!

In reality, the dose you need to take to get ill is huge:

A comprehensive review of the literature revealed that the serum 25(OH)D concentrations associated with hypercalcemia were almost exclusively the result of very large doses of vitamin D, and in all instances serum 25(OH)D concentrations reached concentrations well into the hundreds and even thousands of nmol/L (44). This is consistent with the data derived by Mason et al (45) and reported recently by Morris (46), which concluded that, on the basis of the relation between the 2 parameters, a serum 25(OH)D concentration of ≥700 nmol/L may be needed to evoke hypercalcemia in normal adults.

With 40,000 IU/day you will only barely approach such dangerous levels. Count Iblis (talk) 03:36, 15 July 2011 (UTC)

Is there some bit of knowledge we can help you learn about, Count, or are you just interested in ranting here? This sort of long, wall-of-text rant isn't really appropriate for the refdesks, and as you aren't a noob, I wouldn't have expected you to be reminded of that. --Jayron32 03:43, 15 July 2011 (UTC)

Questions: What proportion of the human population has a diet that includes vitamin D in such quantities? And did our hunter-gatherer ancestors routinely get vitamin D in such quantities? And if so, how was this obtained? (I don't actually know the answer to any of these questions - they aren't rhetorical, for me at least). It seems to me that natural selection can hardly have made us dependant on vitamins we don't get from our diet, so I have to ask what has changed that makes it so essential to do anything other than eat the same stuff we have been, and carry on procreating at an alarming and unsustainable rate... AndyTheGrump (talk) 03:47, 15 July 2011 (UTC)

For reference the practice is called Megadosing or Megavitamin therapy. There is really very little if any evidence that megadosing on ANY vitamins is a good idea. Even our Vitamin D article has some information which makes it sound like a bad idea: Using information from the National Health and Nutrition Examination Survey a large scale study concluded that having low levels of vitamin D (<17.8 ng/ml) was independently associated with an increase in all-cause mortality in the general population.[153] However it has been pointed out that increased mortality was also found in those with higher concentrations, (above 50 ng/ml).A sophisticated August 2010 study of plasma vitamin D and mortality in older men concluded that both high (>39 ng/ml) and low (<18 ng/ml)) concentrations of plasma 25(OH)D are associated with elevated risks of overall and cancer mortality compared with intermediate concentrations. Vespine (talk) 04:08, 15 July 2011 (UTC)

Our hunter-gatherer ancestors obtained most of their vitamin D through photosynthesis. I've heard anecdotal evidence (a nutritionist told me) that less than an hour of average African savanna sunshine per day onto a quarter of the total skin area is sufficient to supply all the Vit D a human needs. Roger (talk) 09:35, 15 July 2011 (UTC)

On one point above, breast-fed infants in the UK are not routinely given Vitamin D supplements, or any other supplements. The World Health Organisation recommends that infants should receive nothing but breast milk for the first six months. That currently forms the basis of NHS advice. Itsmejudith (talk) 14:35, 15 July 2011 (UTC)

Jayron, this is an answer to a question asked half a year ago, I was asked then to report back how I was doing.

AndyTheGrump, as Roger points out, we get vitamin D from exposure to UV radiation. Half an hour in the Sun is enough to produce 10,000 IU. Now, what has happened over the last few centuries is that we're spending so much times indoors that we don't get the 10,000 IU/day and diet will only get you a fraction of this. That may be just enough to prevent problems with your bones.

Vespine, the Wikipedia Vitamin D article has been severy compromized by POV warriors. It's a classic example of how Wikipedia's mantra of "Not Truth" indeed does compromize accuracy, despite what the regulars at WP:V say. There are a huge number of scientific articles that point to doses of the order of a few thousand IU/day being able to prevent illnesses. Almost always when someone (not me) tries to edit in such a result, it's been reverted, on the grounds that one needs to wait until some review article writes about it. However, that standard is not used to include the results suggest that vitamin D may cause health problems.

Itsmejudith, where I live, all breastfed babies are recommended to be given 400 IU/day. Count Iblis (talk) 15:05, 15 July 2011 (UTC)

I had a test for Vitamin D, 25-Hydroxy (Calciferol) and it said the normal range was 30-100 ng/mL. It said any result <10 was "suggestive of deficiency," 10-30- was "suggestive of insufficiency," 30-100 was "suggestive of sufficiency," and >100 was "suggestive of toxicity." 400 units from a daily multivitamin had left me in the "insufficiency" range, on an earlier test, and a daily 1000 unit supplement in addition to that got me up in the high 30's, in the standard range. Two doctors have told me that the middle of the "standard range" would not be better than the lower end of the standard range, though some studies showing benefits increasing through the 30's. Why would someone take mega-supplements and not get a test, citing other random things like pulse rate, when the level might be in the "toxic" range? As for sun exposure, a friend in his 70's has had about 15 pieces of skin cut off his body in operations over the last 2 years due to melanoma attributed by his doctor to large amounts of sun exposure over the years. Seems a high price to pay to save money on vitamins. Edison (talk) 16:38, 15 July 2011 (UTC)

There is still a lack of agreement over the recommended dosage and toxicity levels. Those of us who see no sun for weeks in winter might benefit from high doses, but I'm not sure I want to try the 10,000 IU/day recommended by some researchers (and reported on by the BBC about a year ago) until further research shows that it is perfectly safe. At this time of year, no supplement is necessary, of course, for those of us who are able to go outside in sunlight. Dbfirs 17:16, 15 July 2011 (UTC)

Indeed, and that's why I'm sticking to my own advice :) . Count Iblis (talk) 17:44, 15 July 2011 (UTC)

Let me just mention that Nature had a nice news article about this controversy only last week. Looie496 (talk) 22:59, 15 July 2011 (UTC)

young earth creationism

when i was a child in Sunday school my teacher used to tell me that fossil records were put on the earth by Satan in order to deceive humanity. God knows this sunday school teacher was kooky, but is there any notable strain of young earth creationist thought that endorses this view, and where might I read more about it (not about YEC in general, but specifically about the claim that Satan concocted all the evidence of evolution, etc.)--Fran Cranley (talk) 03:47, 15 July 2011 (UTC)

Religious questions typically don't go down too well on the science ref desk. What I've learned after taking a bit of an interest in the creationism debate is that it's essentially pointless trying to reason with creationists. I've debated with creationists who basically change their stance on a point from one argument to the next to suit their view, then fail to understand why that might be a problem in their position. I don't think they really have strict "sects" or "doctrines" delineated by details such as the argument you describe, I think for the most part it's just a case of "reject the scientific evidence for evolution" and everyone just fills in the gaps as best as they can.Vespine (talk) 05:35, 15 July 2011 (UTC)

There are some articles about research institutes like Geoscience Research Institute and Institute for Creation Research plus the Creation Research Society that may be a good place to start looking for relevant information/links. To be fair, having to stare at fossils when it's freezing cold and wet for a prolonged period of time is enough to make even an atheist geoscientist believe they were put there by Satan. Sean.hoyland - talk 06:49, 15 July 2011 (UTC)

Where in scripture does it say that God granted Satan the right to create? Plasmic Physics (talk) 07:25, 15 July 2011 (UTC)

Nowhere, but then again, it also says nothing about birth control being evil, but that hasn't stopped the entire Roman Catholic Church from crusading against it. -RunningOnBrains^(talk) 07:52, 15 July 2011 (UTC)

I don't accept the RCC's authority over religious matters, especially since they have injected so much of their own doctrine into scripture throughout the times. The assumed authority which they entertain, leads their followers to blindly place their trust in their word, without confirming in the scriptures for themselves, as is instructed within it in any case. This is kind of ironic, since the only way you would know that, is if you actually bothered to read the scriptures. Plasmic Physics (talk) 08:08, 15 July 2011 (UTC)

The scriptures were written by humans too. Why trust them over the humans in the RCC? Or vice versa? thx1138 (talk) 14:33, 15 July 2011 (UTC)

As a more accessible example: charging of interest on a loan is expressly forbidden by the Jewish, Christian, and Muslim holy books, and yet it seems that does not stop the entire world from running on it. -RunningOnBrains^(talk) 13:45, 15 July 2011 (UTC)

I think a more common YEC explanation of fossils is that they are the remains of antediluvian life. As has been noted, the idea that they were created to deliberately deceive humanity - either allowed by God or directly created by God - leads to a tricky moral dilemma. Gandalf61 (talk) 08:44, 15 July 2011 (UTC)

Professor Ian Plimer, professor of mining geology at the University of Adelaide (in Australia), wrote a great book titled Telling Lies for God. That title says it all. Dolphin (t) 08:49, 15 July 2011 (UTC)

There is no "God" to science. Zzubnik (talk) 11:08, 15 July 2011 (UTC)

Isn't it great that everyone has the right to have an opinion? Plasmic Physics (talk) 11:10, 15 July 2011 (UTC)

Einstein wrote about his belief in a "cosmic religion" in 1930. Years later in a letter he wrote "I cannot conceive of a personal God who would directly influence the actions of individuals or would sit in judgement of creatures of his own creation. My religiosity consists of a humble admiration of the infinitely superior spirit that reveals itself in the little we can comprehend about the knowable world. That deeply emotional conviction of the presence of a superior reasoning power, which is revealed in the incomprehensible universe, forms my idea of God." He also said "God is cunning but not malicious," "God does not play dice," and "I want to know how God created the world." He said "I am not an athiest." A Deist is not an athiest(though I'm not sure if Einstein was a Deist like some of the US Founding Fathers, who believed in a God who was like a great cosmic watchmaker who built the universe and set it in motion, then stepped back. Edison (talk) 16:21, 15 July 2011 (UTC)

I agree. If everybody had the same opinion, life would be boring, there would be no discussion, no passion. Zzubnik (talk) 11:34, 15 July 2011 (UTC)

I disagree with Zzubnik on this. I personally find opinions very boring. Facts and hypothesis are much more interesting. And you can discuss facts and hypothesis, so there would still be discussions. --Lgriot (talk) 12:07, 15 July 2011 (UTC)

I am inclined to disagree with myself and agree with Lgriot. — Preceding unsigned comment added by Zzubnik (talk • contribs) 13:00, 15 July 2011 (UTC)

The book Omphalos by naturalist Philip Gosse, 1857, points out that living things go in cycles, and always bear evidence of some earlier existence, which he called "prochronism." See Omphalos hypothesis. Gosse was not arguing against God having created the world, he was just arguing that whatever instant it was created, it would have pointed to a spurious earlier existence. Unless Adam and Eve were bald, they were created with hair that implied growth before existence. The same view would not rule out seemingly ancient fossils, light coming from stars billions of lightyears away, mountains seemingly eroded over millions of years, or layer after layer of sediment with evidence of evolving forms of plants and animals. He did point out that the world could have been created in 1857 with a complete historical record. . Creationists I have questioned often agree that when God created trees in the Garden of Eden, that is Adam had cut one down on his first day there, he would have found tree rings in it which suggested it had been there for years. It would not have been some odd homogenious plastic wood material inside, although some creationists picture Garden of Eden trees with no growth rings inside, and Adam and Eve without navels. Animals and plants would generally have misleading evidence of prior existence. Religionists of the 1850 complained that it would "make God out to be a liar." Edison (talk) 17:01, 15 July 2011 (UTC)

That's, of course, why it is impossible to use reason to argue with YEC proponents, or any other form of intelligent design/creationism belief. One can literally argue that God created the entire universe one second ago and did so with everything in it in the state it is right now, including our memories, and such an arguement requires no actual evidence to back it up, because any evidence wouldn't be able to prove or disprove the assertion. It is an unfalsifiable proposition and so holds absolutely no scientific merit at all. It's completely pointless to try to argue the point. In other words, one can hold that such a statement could be true for any given range of "could", but one cannot operate scientifically around that statement, so there is no point in trying to prove it scientifically. From a scientific point of view, such propositions can be ignored as though they don't exist. --Jayron32 17:11, 15 July 2011 (UTC)

I don't see why it would have to be Satan. It seems to me that a Creationist could argue that God placed fossils and other spurious things on Earth in order to test our faith. This argument would be virtually impossible for scientists to refute; it is remarkable to me that it is so rarely used. Looie496 (talk) 17:08, 15 July 2011 (UTC)

Much of recorded history includes religious authorities trying to revise or explain superstitions, including by apologism which often results in the creation of other superstitions. The idea that satan placed fossils underground is probably in the folklore stage, without much written documentation beyond hushed whispers. One might wonder whether all of the evidence in biology and radiochemistry suggesting a billions of years-old Earth will go through the same stages. 99.24.223.58 (talk) 18:51, 15 July 2011 (UTC)

cancer stage

How long will it usually take for a carcinoma to transfer from one stage to another? — Preceding unsigned comment added by 199.224.149.10 (talk) 09:39, 15 July 2011 (UTC)

This is really an "it depends" kind of question. "Cancer" is not one disease, but many. The time it takes to progress from one "stage" to another depends on the definition of "stage" for a given cancer, and it depends on the multitude of individual factors within an individual. One of main factors is probably random chance -- whether a mutation arises that gives that cancer cell an advantage and allows it to spread faster than other cancer cells. This is also a very difficult question to answer scientifically, since most cancers are detected when they are large enough to be seen on some type of screening study or because they are causing symptoms (like a lump, or bleeding). We have no idea how long the "cancer" has been present in that person prior to detection. We can assume a constant growth rate and project how long it might have taken for one cell to grow to a tumor of a certain size, but that is complete guesswork and makes a very naive assumption (consistent rate of cell growth and death). Once a cancer has been detected, the inclination of the physician is to treat it (remove it or give chemotherapy), which pretty much excludes the possibility of measuring the time it takes for that cancer to progress (and you could imagine that a scientific study designed to measure time to progression would involve serious ethical questions, especially for early stage, more treatable cancers). I don't think you're going to find a simple answer here. --- Medical geneticist (talk) 10:28, 15 July 2011 (UTC)

Zoophilia

I know that not many people have done these types of experiments, but how do higher animals react to rape by a human? Would a female chimp, for example, react in a similar way to unwanted vaginal penetration by a human as a female human? My guess would be yes, since chimps are a monogamous species and presumably don't appreciate sexual contact by a stranger, but I also have no experience with this.

I'm asking because Wikipedia's article on zoophilia implies that much of the debate around it concerns whether or not it's cruel to animals.--140.180.16.144 (talk) 09:40, 15 July 2011 (UTC)

"chimps are a monogamous species"...I think not. Sean.hoyland - talk 09:43, 15 July 2011 (UTC)

I want to know why do some animals like Orangutan are attracted to humans? They are different species. then how do the attraction occur. How do they feel about it? Is it reverse zoophilia, homophilia? --111Engo (talk) 10:12, 15 July 2011 (UTC)

Not sure what you mean by "why", or "how do they feel about it", unless you're looking for an evolutionary reason. Why are you attracted to human males/females? How do you feel about it? I don't think orangutans have any more of a reason or justification than you do. --140.180.16.144 (talk) 11:33, 15 July 2011 (UTC)

Why do I attracted to humans? Because it is coded in my DNA, my gene, it is my biological instinct. But Orangutans have different gene. This is why I am asking why do they attracted to humans? --111Engo (talk) 11:40, 15 July 2011 (UTC)

Also is there other instances where other animal are attracted to humans? --111Engo (talk) 10:14, 15 July 2011 (UTC)

What about dogs? Then again, they would go for inanimate objects, so that doesn't say much. Plasmic Physics (talk) 11:49, 15 July 2011 (UTC)

I remember reading a news report on the multiple cases of sexual abuse of horses ocurring during nights in Texas somewhere. In the news report, it was described how the horses became apprehensive toward humans, and developed a general mistrust. If anyone can track down that article, it might be of some use. Plasmic Physics (talk) 11:55, 15 July 2011 (UTC)

These are just good friends. (video) Cuddlyable3 (talk) 14:49, 15 July 2011 (UTC)

Does knowledge of psychological experiments influence participants' behaviour?

I'm curious about whether psychological experiments are influenced by participants' foreknowledge, particularly for experiments where people end up behaving in ways they wouldn't expect to. For example, if a researcher decided to recreate the Stanford Prison Experiment (or the Milgram experiment or the Asch conformity experiments or something similar), would the results be different if the participants were aware of these experiments, even though they were not told they were taking part in one?

PS. Since I'm here - I vaguely recall reading about an experiment which studied peer pressure or conformity (I think), where a group of people were instructed to remain in a room. After some time, they started hearing noises - screams or cries for help outside the door. All but one of the group were secretly actors, who were to discourage the non-actor from investigating the noise. I haven't been able to find information on this and can't remember the name - did I imagine it? --Kateshortforbob _talk 13:06, 15 July 2011 (UTC)

Knowledge that one's behaviour is under observation always puts doubt about how the results of the types of experiment you mention was influenced. More credible results may come from analysis of behaviours in non-experimental conditions with the analysis unknown to the subjects. The main difficulty then is to show whether an observed correlation implies causality. Cuddlyable3 (talk) 14:42, 15 July 2011 (UTC)

Some folks have read about famous psychology experiments such as the Milgram experiment, or seen them portrayed on TV, but a great many are quite ignorant, as shown by the lackluster results of many tests of general knowledge. A clever experimentr can make subjects think the experiment is about one thing, when it is really about something else. It was very easy for Milgram to do his experiments back in the day (Especially because there were then few rules against causing psychological harm to participants in such experiments). Many experimenters are not very scientific or careful in their work, and just want to get their master's thesis accepted or to get published and gain tenure, so they may ignore participants "figuring out what is going on." A good experiment would have some kind of awareness assessment questionnaire, to determine if the subject was aware of the published related research. Charlatans just go ahead and publish studies, ignoring whether subjects figured out any ruse the experiment was engaged in, or whether the demand conditions of the experiment affected the results, or whether the subject had "figured out what the (unstated) point of the experiment was," or whether the subject had invented a strategy such as noticing in a reaction time experiment with 2 response choices, that one response never repeated more than 3 times in a row, allowing an "instant" response after the same response was called for 3 times in succession. (The last issue can be dealt with by having practice runs or noncounting runs which have the same response repeated more than 3 times in a row). Edison (talk) 15:59, 15 July 2011 (UTC)

You have a good point -- it has often seemed to me that psychologists too frequently presume that experimental subjects fully believe the stories they are told. Regarding the second part of the question, interest in that topic was first provoked by shock at the circumstances of the murder of Kitty Genovese in 1964, and led to research that is described in our articles on the bystander effect and diffusion of responsibility. Looie496 (talk) 16:56, 15 July 2011 (UTC)

capacitance

In alternating current ,the potential drop across a small capacitor is very large compared to a larger capacitor since smaller capacitor has more reactance(charging and discharging current is less). but my doubt is we know that voltage means the charge difference,but accumulated electrons on smaller capacitance plate is very less compared to a larger capacitance plate. according to voltage meaning,the larger capacitance has more voltage compared to smaller capacitance but smaller one has more voltage drop why? please clarify my doubt in deep and also in 3d picturesvsnkumar (talk) 13:57, 15 July 2011 (UTC)

An ideal capacitor is wholly characterized by a constant capacitance C, defined as the ratio of charge ±Q on each conductor to the voltage V between them:

$C={\frac {Q}{V}}$

That means that changing the voltage on a large capacitor involves moving a larger charge Q than the same voltage change on a small capacitor. See the article Capacitor. It doesn't have much of 3-D pictures except photographs of real capacitors. Cuddlyable3 (talk) 14:29, 15 July 2011 (UTC)

"Voltage means the charge difference" is wrong. Voltage is partly determined by the charge difference, but also by how much the positive and negative charges are separated. Looie496 (talk) 16:43, 15 July 2011 (UTC)

You are right to express doubt that voltage is determined by capacitance because the voltage drop will depend on the circuit. I assume that you were thinking of the two capacitors connected in series. You might find our article Hydraulic analogy helpful in visualising why the "higher pressure" is across the smaller "tank with rubber sheet". Dbfirs 16:58, 15 July 2011 (UTC)

Do you have an article about hydrocution:

[[24]]? Also see Google translate version: [[25]] — Preceding unsigned comment added by 88.8.79.148 (talk) 14:56, 15 July 2011 (UTC)

Is it cold shock or thereabouts ? Sean.hoyland - talk 15:03, 15 July 2011 (UTC)

(edit conflict) The french article says (by my own translation) that "Hydrocution is a cardiopulmonary arrest caused by a difference in temperature between a liquid (usually water, hence the prefix "hydro") and the skin. The shock can cause a loss of consciousness and drowning. According to "Éditions Larousse", the term is recent, 1953 from "electrocution", the self-same term created in English by combining "electro" and the "cution" from "execution". I'm not sure what the term in English may be, but the nearest concepts I can think of is that this is Shock (circulatory) brought on by hypothermia. I'm not sure there is a medical term for hypothermia specifically caused by being immersed in water. The subsection Hypothermia#Water seems to be the nearest en.wikipedia content on this, but perhaps someone who spends more time in the medical field could find you a better link. --Jayron32 15:12, 15 July 2011 (UTC)

"Hydrocution" seems like a silly neologism, because it appears to imitate "electrocution," as a form of "execution," but does any country really try to kill the condemned by dunking them in cold water, at least since the end of witch hunts in the 17th century. Edison (talk) 15:43, 15 July 2011 (UTC)

Irrelevant comment on a nation.
The following discussion has been closed. Please do not modify it.
Hey, give the French a little bit of credit. They invented a new word. For the French, that is an amazingly rare event, as far as they are concerned the French language is an immutable gift from God himself, and to alter it is tantamount to blasphemy. People have gone to the guillotine for less. --Jayron32 16:45, 15 July 2011 (UTC)

Wiktionary has an entry but with a very general definition. I don't think the word deserves a Wikipedia entry in English unless it becomes an accepted medical term. Dbfirs 16:43, 15 July 2011 (UTC)

Is this related to the Mammalian diving reflex? Roger (talk) 16:56, 15 July 2011 (UTC)

snow cover

About what % of the world's landmass is continuously covered by snow for at least 2 consecutive weeks in an average year? Googlemeister (talk) 15:32, 15 July 2011 (UTC)

That may be a difficult number to come by, because it's so specific. (For example, that criteria is not one of the standard data product results generated by NOAA's snow climatology group). But, you can find archived raw data for U.S. and international snow cover at the NOAA National Operational Hydrologic Remote Sensing Center archive page. They also produce interactive reports and maps for recent data. The US Snow Climatology center website may also be useful.

NASA's Global Snow Coverage interactive map is made using MODIS data; you can download MODIS data directly from NASA MODIS data archive and analyze that data yourself. MOD 10 intermediate data product is listed as "snow cover"; and the algorithm used to derive that parameter is provided for your use on the Algorithms page. There is a nontechnical overview explaining how to derive snow-cover from infrared observation.

Presumably, to proceed, you will need to download a year (or multiple years') of archived data; and you can easily construct a program to determine the number of points that satisfy the "snow cover" criteria for 2 consecutive weeks during the year. Nimur (talk) 15:50, 15 July 2011 (UTC)

tetanus

Is it possible to get tetaus from penguin bites? I work with penguins and often get biten, I have not had a booster and wat to know what the chances are of getting infected with tetanu. — Preceding unsigned comment added by 41.2.63.234 (talk) 18:57, 15 July 2011 (UTC)

Which species of penguins do you work with, and what is the location? Googlemeister (talk) 19:03, 15 July 2011 (UTC)

We are not permitted to give medical advice on Wikipedia, and an answer to this question would definitely be medical advice. You should discuss the question with an appropriate health care provider. Looie496 (talk) 19:18, 15 July 2011 (UTC)

summers in Tundra climate and Northern Siberia

Do tundra climates often get 62 F or higher in summer temperatures. That is because western coast of Greenland gets over 60F in summer quite often. Dfd cities in Russia like Yatsuk and Verkhoyanysk gets 15 straight days in 90sF. That is why I am wondering about the tundra northern coasts parallel to Siberia/Russia around 70 degrees latitudes, are they likely to get above 60s or 70/80 in the summertimes. Is this common enough for the near 70 degree latitude lands to get 62 F or higher in the summer seasons. Is this possible they can have few days in the 70s or 80s in tundra lands.--69.226.40.132 (talk) 20:15, 15 July 2011 (UTC)

Tundra suggests they might be defined by their low temperatures and inhospitality to trees than by their high temperatures, and coastal climates are usually more moderate, especially in areas where tropical storms are uncommon. So I can't answer a question phrased as "often" very confidently or definitively, but I suspect the answer is yes. 99.24.223.58 (talk) 20:27, 15 July 2011 (UTC)

When I said common I meant at more than once a year in the summer period. Yakutsk is 62 N latitude it is still getting days above 90s, been a week, same as Verkhoyansk, this week it will have one day in the 90s. I was shocked by that, subarctic term seems overated sometimes they suppose to have average temperatures in summer month below 70s, it is actually scorching in the Siberia arctics than moderating what the temperature suppose to be. I was surprised. Upervavik, Greenland is 73 N latitude, it does get 60s at least once a year. All the west coast Greenland gets 60s at least once a year. I was asking if northern tip of Siberia gets 70s/80s nearly every year or only some years. I was asking if they get 60s more than once year or not every years. Go to wunthergrounds. Barrow, Alaska gets 60s almost every year. Common, semi-common is arbituary vocabulary.--69.226.40.132 (talk) 22:47, 15 July 2011 (UTC)

Androgens

The Prenatal development article says that until week 5 a fetus is not male or female, only once androgen production starts does it turn into a male. If the androgen production was supressed somehow, would a baby with a Y chromosome develope a female body type and have a vagina? 109.209.3.93 (talk) 20:25, 15 July 2011 (UTC)

Maybe. There are several degenerate chromosome conditions which result in a variety of sexual organ development. The development of any of the several dozens of tissue types in a typical mammal are probably controlled by multiple chemical signaling paths. So while many of these systems prevent problems, there are a lot of moving parts and things will go wrong on rare occasions. While any major birth defects are likely to result in a nonviable fetus, the sexual organs are not vital for the individual's survival, so sexual organ differences are some of the more common congenital malformations to be observed in healthy births. Many of them can be so completely corrected by surgery that the patient will be able to live a healthy sex life with no idea that there was ever any problem. More often, births with no apparent malformations will be infertile, but this is rare in general. For more information, see PMID 20079588 and PMID 20541154, the former of which lists an email address for a corresponding author if you have more detailed personal questions or seek a referral to a specialist in your locale. 99.24.223.58 (talk) 20:53, 15 July 2011 (UTC)

The hormonal control of internal genital development is somewhat distinct from the development of the external genitals. If a functional Y chromosome is present, the SRY gene will kick off a cascade that leads to the formation of testes, production of antimullerian hormone, and regression of the female internal organs (Mullerian ducts). Assuming that only androgen production is suppressed, the baby would most likely have male internal genital structures but the testes would fail to descend (cryptorchidism) and the external genitalia would appear to be female. This is similar to what happens in androgen insensitivity syndrome, where instead of lacking the androgen hormone, the body is unable to respond to the androgen. The converse situation is the situation of hormone excess (see congenital adrenal hyperplasia for example), where a female fetus can develop normal female internal structures but undergo masculinization of the external genitalia due to the excess androgen hormone. Of course, things can get a lot more complicated depending on the situation. See intersex for more information. --- Medical geneticist (talk) 21:38, 15 July 2011 (UTC)

Estrogen

I read somewhere that there is Estrogen in rain water.

1. How did it get there?
2. How comparable is the amount of Estrogen in rain water to the amount of Estrogen a m2f transexual person takes to develope breasts?

109.209.3.93 (talk) 20:25, 15 July 2011 (UTC)

For clarity, I guess you are talking about environmental exogenous hormones. Sean.hoyland - talk 20:35, 15 July 2011 (UTC)

The article about Hormone replacement therapy (male-to-female) gives information on estrogen use but does not specify dose levels quantitively. Cuddlyable3 (talk) 23:16, 15 July 2011 (UTC)

Radio flux

The present age has many radio stations and other radio transmitters such as mobile/cell phone masts, not to mention electric wiring. How much radio energy would pass through a one metre cube of air per second, situated near the ground in central London or New York? How would that compare with the amount of light or infra-red energy passing through? 2.97.208.91 (talk) 21:36, 15 July 2011 (UTC)

Unless someone spends a lot of time next to a radio transmitter, the amount of energy they absorb in the infrared would be much greater. Isn't the thermal blackbody peak of room temperature somewhere in the infrared? It is important to point out that natural ionizing electromagnetic radiation is usually only on the ultraviolet side of the visible spectrum, except in fires maybe. 99.24.223.58 (talk) 22:26, 15 July 2011 (UTC)

I was hoping for some numbers, in watts. 92.29.125.215 (talk) 23:12, 15 July 2011 (UTC)

Sorry, watts is not the proper unit, because ionizing watts are much more deleterious than non-ionizing watts. Also, the increased incidence of brain cancer in cell phone users mentioned in PMID 21084892 is much more easily explained by exposure to trace industrial solvents on handheld (and ear-held under high humidity perspiration conditions) electronics than the energy of a cell phone's radio transmitter. Even if the same amount of radiation was transmitted as ionizing radiation, the carcinogen exposure would pose the greater risk. Please see PMID 16580876 for more information. 99.24.223.58 (talk) 23:19, 15 July 2011 (UTC)

Double nuts on bolt

Is it true that putting two nuts on a bolt rather than one means that the nuts are less likely to come loose from vibration etc? If true, what is the engineering reason for this? 2.97.208.91 (talk) 21:40, 15 July 2011 (UTC)

See this page. --Jayron32 21:42, 15 July 2011 (UTC)

Seems like something that should be a see-also at Locknut or listed at Positive locking device, but not sure what the target page would be. DMacks (talk) 22:05, 15 July 2011 (UTC)