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May 5

Children Raised Alongside Dogs

First of all, I am not referring to feral children. I've been watching documentary after documentary about the shared evolutionary history of humans and our canine friends (e.g., how domesticated dogs are basically a separate species from wolves due to their interactions with us), and was wondering if there are any studies regarding children raised alongside dogs from birth (that is, birth of the human child). Do they cope differently or "better" with dogs? With Humans? I did hear, on Animal Planet, that dog owners live three more years on average, but they didn't give many details. I guess I am looking for psychological research, but info from any field is welcome. I don't have access to medical/psych journals via my (liberal arts) school, and on first efforts it seems to be too vague of a google search. Any info or direction in which to search will be much appreciated, as I f***ing love dogs and anything related to them. --Lazer Stein (talk) 00:33, 5 May 2011 (UTC)

Dog#Health benefits for humans has some references. Clarityfiend (talk) 02:11, 5 May 2011 (UTC)

The domestic dog: its evolution, behaviour, and interactions with people has information about the psychological benefits of having a dog including a section on children (developmental benefits, page 168). Unfortunately, the following page is missing, but your local library might be able to get you a copy. The pages which were available made a very interesting read. --Kateshortforbob _talk 09:16, 5 May 2011 (UTC)

Let me mention (since many people are not aware of this and it is a frequent cause of confusion) that Google Books often shows different sets of pages to different visitors. Looie496 (talk) 16:25, 5 May 2011 (UTC)

Well, there's at least a clear effect in the reverse direction: people from some Arab countries very rarely encounter dogs as pets while they are growing up, and often have great difficulties interacting with them -- they can't distinguish a friendly dog from an angry or scared dog. Looie496 (talk) 16:25, 5 May 2011 (UTC)

Infant mortality accounts for those three years if you assume a baby cannot be a dog owner. – b_jonas 08:44, 6 May 2011 (UTC)

Groundhogs Immune to Poison Ivy?

I found a groundhog and its burrow along the side of the road. It was foraging for plants and carrying them back to its home. But when I knelt down to touch it, my hand brushed against the plant in its mouth and I suddenly developed a rash. Undoubtedly, it was Poison Ivy but I didn't know until now that Groundhogs were immune to it? --Arima (talk) 01:53, 5 May 2011 (UTC)

I had always thought that humans alone were vulnerable to urushiol-induced contact dermatitis. I don't really know whether that is accurate. this page (talking about poison oak rather than poison ivy; poison oak is the one I have more experience with) asserts that Animals with fur usually don’t suffer skin irritation, although a dog can develop symptoms on its nose or underbelly. Livestock can graze on the tender foliage with no adverse effects. --Trovatore (talk) 01:58, 5 May 2011 (UTC)

(By the way, it's extremely uncommon to "suddenly" develop a rash in response to a Toxicodendron species. In my experience it takes a day or so, possibly twelve hours before you feel the first prickly hint of what's to come. If you experienced symptoms immediately, I would suspect stinging nettle or possibly some plant that you personally happen to have an allergy to.) --Trovatore (talk) 02:03, 5 May 2011 (UTC)

Now that you mention it, the plant probably wasn't poison ivy. It was small with a stiff shoot and I did notice hairs on its stem. --Arima (talk) 02:15, 5 May 2011 (UTC)

There is so much poison oak where I go hiking that I judged it prudent to teach myself to recognize it without the leaves. It's also quite a pretty plant and I've taken quite a few pictures. You can see a couple without leaves on my Flickr account at http://www.flickr.com/photos/30973445@N02/4340108220/in/photostream and http://www.flickr.com/photos/30973445@N02/4045487431/in/photostream. I think poison ivy should look about the same without leaves, though I can't be sure. --Trovatore (talk) 02:19, 5 May 2011 (UTC)

No. It definitely wasn't poison oak I saw in the groundhog's mouth. --Arima (talk) 02:33, 5 May 2011 (UTC)

Although you state that you now do not believe it was poison ivy, it is still incorrect to assume that if one groundhog was not allergic to urushiol (in the poison ivy) then all groundhogs are not allergic to it. I happen to be a human and I have absolutely no reaction to urushiol. That does not imply that humans are not allergic to it. Most are. To further the point, I am highly allergic to the oil of orange peels. I've only ever met one other human who is also allergic to orange oil. -- kainaw™ 14:28, 5 May 2011 (UTC)

The groundhog had a "stinging nettle" plant in its mouth when I tried to touch it. Not Poison Ivy.--Arima (talk) 01:09, 6 May 2011 (UTC)

What is the prediction based on this allergic reaction? Count Iblis (talk) 15:29, 6 May 2011 (UTC)

Most animals are immune to the effects of poison ivy, a plant related to cashews, per "Wildlife and plants: Palm to polar bear, Volume 13" (2007. "North America's Most Amazing Plants"(2008) says deer eat poison ivy. An "imponderables book" says that vets have observed skin reactions from poison ivy in some animals. Various books say birds eat the berries, and ruminants commonly eat the plant. The last work cited says it is an allergic reaction that causes humans to suffer from contact, rather than a "poison" per se. So it would be no more amazing for an animal to eat the plant without an allergic reaction than for me to eat without discomfort dairy, shellfish, wheat, and peanuts, which would cause uncomfortable or deadly reactions in some other people. Edison (talk) 18:34, 6 May 2011 (UTC)

Well, urushiol is a little different from common allergens. In fact, strictly speaking, urushiol itself is not an allergen at all, but rather a hapten. It binds to proteins in your skin to form an allergenic complex.

True immunity to this effect, among humans, is rather rare I think. A fair percentage of people have simply not been sensitized to it, yet, and appear to be immune, but with repeated exposure would eventually develop a response.

So there is actually a pretty big distinction from most allergens. Most allergies are the exception; sensitivity to urushiol (or at least potential sensitivity) is present in a large majority of humans and can be considered to be the typical response. Why it is not the typical response in, for example, deer, is I think a reasonable question. --Trovatore (talk) 18:54, 6 May 2011 (UTC)

I remember telling a woman that her horse was eating poison ivy. She just laughed and laughed, and said she would be sure to warn her horse against eating any of the plant. Now I will eat some cashews, peanuts, wheat, dairy products, shellfish and (perhaps) rub poison ivy on my skin. Edison (talk) 01:43, 7 May 2011 (UTC)

I don't understand why you would do that. The last one, I mean. --Trovatore (talk) 01:59, 7 May 2011 (UTC)

High-temperature superconductors

What's the highest-temperature superconductor currently known? --75.40.204.106 (talk) 02:16, 5 May 2011 (UTC)

High temperature superconductivity says "mercury barium calcium copper oxide" (HgBa₂Ca₂Cu₃O_x) which reaches 135 K at atmospheric pressures. Dragons flight (talk) 02:25, 5 May 2011 (UTC)

Baldwin IV of Jerusalem and Leprosy

I understand that the diseases called "leprosy" in ancient and medieval times don't correspond one-to-one with what is now called leprosy, i.e. Hansen's Disease. Do people know for sure (or have a best guess) as for what Baldwin IV was infected with? Was it likely Mycobacterium leprae (modern leprosy), or was it likely some other skin disease, such as a fungal Dermatophyte like Trichophyton schoenleinii or related species. Or do we really not have enough information? Thank You. Buddy431 (talk) 04:07, 5 May 2011 (UTC)

Actual leprosy does damage to much more than merely the skin; I'm pretty sure if you had Baldwin's skeleton, you could narrow down which disease he suffered from. Fungal skin infections wouldn't have the same "deep" effect that leprosy would. I don't see anywhere where it says in our article if we even know where Baldwin IV was buried, so it may be entirely unknowable if he did or didn't have Hansen's Disease. --Jayron32 05:47, 6 May 2011 (UTC)

I'd go with "not enough info". Most early disease observations were rather vague. Even with modern testing it's not always possible to distinguish diseases, back then it would have been virtually impossible. StuRat (talk) 05:55, 6 May 2011 (UTC)

Most such observations were rather vague, yes, but apparently the description William of Tyre gives is quite detailed. Bernard Hamilton's The Leper King and His Heirs: Baldwin IV and the Crusader Kingdom of Jerusalem and A. Guerrero-Peral's "Neurological evaluation of the leper king Baldwin IV of Jerusalem" seem agreed that it was Hansen's disease, and only disagree as to whether it began as tuberculoid leprosy, borderline tuberculoid leprosy or primary polyneuritic leprosy. --Antiquary (talk) 18:57, 6 May 2011 (UTC)

This page says; "He contracted leprosy in childhood, possibly from a member of the Royal household affected with a mild form of the infection, and developed the initial symptom of skin anaesthesia just prior to his puberty (circa 9-13 years of age). There was no mention of any other obvious skin lesions at this stage suggesting a polyneurotic form of the disease. This advanced to a lepromatous form during the pubertal years, so that by his early twenties, the nerve damage had led to severe muscle weakness requiring him to be carried in a litter. Weakness of the facial muscles probably led to corneal ulceration causing eventual blindness. In addition the bacteria had multiplied in the skin of the limbs and face to form disfiguring plaques and nodules, and destroyed the nose. He died prematurely in 1185 at the age of twenty-three years." Alansplodge (talk) 19:02, 6 May 2011 (UTC)

That's sweet guys - I didn't realize his symptoms had been described in such detail. Buddy431 (talk) 21:29, 6 May 2011 (UTC)

Is this complete rubbish: "Wind turbines fan the flames of moorland fires"?

Wind turbines near me have been stopped recently. According to a News Article this is to avoid them fanning the flames of nearby moorland fires. This sounds like complete rubbish, as wind turbines take energy from the wind rather than adding it, so I would expect them to reduce the fanning affect of the wind. Could there be any reason for turning them off? I was wondering whether a stationary wind turbine might slow the air more than a moving one? (If a stationary turbine does slow air more it would seem to be most unfair on the generating company to tell them to stop - a bit like telling a truck driver on a moorland road that he must stop his journey because his vehicle slows down the wind slightly!) Or perhaps a functioning turbine brings higher altitude faster winds down to ground level? Or does it cause some sort of turbulence conducive to burning? I would have thought all such affects would be minor, could there be any significant affect? -- Q Chris (talk) 07:33, 5 May 2011 (UTC)

I agree that the effect of the turbines is unlikely to have a measurable effect on the fires, otherwise they could be run in reverse to cancel out the wind! The real reason for turning them off is "so the helicopter can fly in between them and drop water but also there was a risk the fire could burn down to the cables". Dbfirs 08:21, 5 May 2011 (UTC)

I agree with the OP - "complete rubbish". I do wonder about the knowledge level of the journalist responsible. I note that his paper has generously let him remain anonymous, a common approach for lower class journals. HiLo48 (talk) 08:39, 5 May 2011 (UTC)

By far the "best" piece of journalism I've ever seen. To quote an authoritative source, "WINDMILLS DO NOT WORK THAT WAY" -RunningOnBrains^(talk) 08:46, 5 May 2011 (UTC)

So the OP is wrong and the news article makes no such rubbish claim. Cuddlyable3 (talk) 09:49, 5 May 2011 (UTC)

"The inferno, thought to have been started deliberately, has wrecked moorland near Wainstalls in West Yorkshire, forcing wind turbines to be switched off to avoid fanning the flames." Third paragraph. -RunningOnBrains^(talk) 10:16, 5 May 2011 (UTC)

Thanks. It was my oversight, now struck out. I apologise to the OP. Cuddlyable3 (talk) 10:36, 5 May 2011 (UTC)

I suspect that the opposite is in fact true. Fires can sometimes cause their own high winds, and wind turbines usually shut down in very strong winds to avoid damage. Googlemeister (talk) 18:12, 5 May 2011 (UTC)

I also doubt this claim, but I couldn't rule it out on first principles. Windmill blades are at an angle to the wind - is it possible that the windmills could catch wind that is above the treeline and push some of it downward in eddies as they spin? Has anyone here stood directly under one of the things - can you feel a breeze from above as they rotate? Wnt (talk) 23:15, 5 May 2011 (UTC)

Yes, and I haven't noticed a breeze. In any case, the effect would be absolutely minimal. The linked article actually explains the reason (as I cited above), and the journalist (or more likely his editor) was foolish in writing a headline that contradicts the accurate report in the main text. Dbfirs 15:59, 6 May 2011 (UTC)

Imagine a hole drilled completely through Earth...

I have a textbook in Physics with notes for the teacher, and as I'm not a physics teacher, these are confusing.
The text for the student says (in short): "Imagine falling down a hole drilled completely through Earth, from North to South pole. At the beginning of the fall, your acceleration would be g, but you’d find acceleration progressively decreasing as you continue toward the center of Earth. Why? Because as you are being pulled “downward” toward Earth’s center, you are also being pulled “upward” by the part of Earth that is “above” you."
So far so good.
But the note for the teacher says: "Explain that, strictly speaking, as a body falls through the tunnel, the part of Earth above doesn’t pull “upward” on it. Gravitational forces from all parts of Earth above the body cancel, assuming uniform density."
This is the part I don't understand. Why do the gravitational forces from all parts of Earth above the body cancel??? Lova Falk talk 08:16, 5 May 2011 (UTC)

Perhaps they meant around rather than above the body (when it is at the centre). Maybe Gravity_of_Earth#Depth will help. Sean.hoyland - talk 08:28, 5 May 2011 (UTC)

Around I would understand perfectly, but I'm not happy with the assumption that the author used the wrong word. The Wikipedia section you refer to is too difficult for me. Lova Falk talk 08:32, 5 May 2011 (UTC)

Perhaps the teacher means forces above cancel with forces below? Or that all the radial gravitational forces cancel, leaving only the net "up" or "down" forces depending on how far through the earth you are on your journey. The wording is ambiguous as you have stated it; it could really mean one of several things. -RunningOnBrains^(talk) 08:42, 5 May 2011 (UTC)

Wow, I really am the worst physicist ever. Shell theorem sounds like exactly what they are asking for.-RunningOnBrains^(talk) 17:56, 5 May 2011 (UTC)

I'm no expert, but perhaps Shell theorem can help you understand it? Jørgen (talk) 08:57, 5 May 2011 (UTC)

Thank you, but that page is also way too difficult for me. Lova Falk talk 09:06, 5 May 2011 (UTC)

Yes, I think that is probably what the author is referring to, Gauss' law for gravity#Spherically symmetric mass distribution, "above" being the spherical shell "above" the body and "below" being the core sphere. This seems to be the book (p 244). Sean.hoyland - talk 09:10, 5 May 2011 (UTC)

Yes, that is the book! Lova Falk talk 09:14, 5 May 2011 (UTC)

In the hole at a distance d from the centre of the Earth, the shell theorem tells us that gravitational forces from the parts of the Earth at a distance greater than d from the centre cancel out. This is what I think the notes mean when they say "the part of Earth above" - it would be clearer to say "further out" rather than "above". We are left with the attraction of a sphere of radius d, which has a mass proportional to d'³, and we are a distance d from its centre, so gravitational attraction inside the hole is proportional to d³/d², which is just d. (I thought Wikipedia would have an article on this well known physics problem, but I can't find one). Gandalf61 (talk) 09:23, 5 May 2011 (UTC)

Who dares suggest that Wikipedia doesn't have an article on something? See Earth's gravity#Depth which makes it clear that the inverse-square law of gravitational force is true for a sphere of uniform density, which our planet is not. Yours may be different. Cuddlyable3 (talk) 09:41, 5 May 2011 (UTC)

While others have covered the physics well, I should emphasize that the textbook is not wrong. The part of the Earth above you pulls you upward - by definition. And that cancels out some of the pull of the Earth below you. A more advanced text will explain how a uniform sphere of mass around you should cancel out, for the same reason that a given pinprick-sized bit of the sun's surface will appear just as bright no matter how near or far you go from it. Wnt (talk) 23:19, 5 May 2011 (UTC)

Imagine a hole drilled completely through Earth, question 2

There is a picture illustrating acceleration during this imaginary situation. It shows that at the North pole, a = g, halfway towards the center of the earth, a = g/2 and at the center of the earth, a = 0. I understand. But we keep falling and halfway from the center of the earth towards the South pole, a = g/2, and at the South pole, a = g. I think it should be a = - g/2 and a = -g, respectively. Am I wrong? Lova Falk talk 08:59, 5 May 2011 (UTC)

If you measure your acceleration as positive to the south you are right. It can be confusing if you just measure acceleration to the center of the earth as it changes direction as you pass through. It looks like you worked that out. Graeme Bartlett (talk) 09:15, 5 May 2011 (UTC)

gradiant of increasing and decreasing acceleration or g in gravity field

this is where the mathematics come to help us :suppose the radius of earth be "r"the movement equation of falling object is :x=1/2 g t²+x₀ then "g"varies in "r-x"ratio for this gradiant we have :dg/dx=cte if we suppose earth mass is hemogenized . so if we draw diagram of "g"it will be line . then for velocity it will be squerd curvature , and for acceleration degree three curvature which zero point is "r=x"and centre of earth --78.38.28.3 (talk) 14:24, 9 May 2011 (UTC)a. mohammadzade

in addition where "r=x" velocity is maximum ,then we have enough velocity for moving toword other edge--78.38.28.3 (talk) 14:43, 9 May 2011 (UTC)

: (ec) Convention has it that "g" acts towards the centre of the earth (centre of mass), so as you wander around the centre, "g" is always a positive real number whose direction changes. If you are trying to analyse a body falling through your hole in the earth then you would want to define "g" relative to some constant direction (such as from north to south pole). In that case you would get -g. However if you drilled a hole from the north pole to a point on the equator (I'll call it the west pole (see Piers Anthony)) then by the end of the hole, gravity is acting at right angles and something more complex than a real number is required. -- SGBailey (talk) 09:16, 5 May 2011 (UTC)

The attractive force of gravity has direction so, like the acceleration it produces, it is a vector. You are right to say that a 180 degree change in ditrection corresponds to a change from + to - (or it could be - to + because the signs are arbitrary). However this suggests that the actual attraction half way down is considerably more than half the surface value. Cuddlyable3 (talk) 09:31, 5 May 2011 (UTC)

Look at the dashed line in that picture. That's the line for a hypothetical earth with uniform density. That's the idealized planet the book is talking about. Dauto (talk) 10:55, 5 May 2011 (UTC)

For "idealized Earth" read "like a Spherical cow that a 17th century alchemist astrologer high on mercury would envisage". Mercury was prescribed then and is to this day by homeopaths to treat syphilis. Cuddlyable3 (talk) 20:55, 5 May 2011 (UTC)

Fact check: In the 19th century, regular medical doctors prescribed "calomel," a deadly mercury compound, for anything from a bump on the head to venereal disease, without any scientific justification, and thus killed or greatly harmed countless patients. Regular medical doctors mantra was "bleed and purge, and give calomel." Homeopaths, on the other hand pointed out the harm from such medications, and the lack of clinical proof of effectiveness, prescribing instead what were basically harmless placebos, in the form of chemicals so diluted that a dose might not contain even a single molecule. Edison (talk) 18:19, 6 May 2011 (UTC)

what are the chances there could be "French Fries Zero"?

You can buy a Coke Zero with literally 0 calories. What are the chances that there could be fake food the same way as there is fake Coke -- with no calories at all? (Just "plastic") but tasting close to the real thing?

In other words, that one day you can say: "I'll have a big mac with zero fries and a coke zero". Thanks. 188.156.67.97 (talk) 16:08, 5 May 2011 (UTC)

I would guess unlikely. A lot of people can differentiate the taste of diet and regular drinks, and that is really only substituting 1 ingredient rather then the entire food. Additionally, food depends not only on taste, but also on texture, so it would add another dimension of difficulty (seeing as a coke doesn't really have much texture beyond a fizzy liquid). The chances of being able to do all of this, and for a similar price to potatos (which are quite cheap) seems unlikely. Googlemeister (talk) 18:10, 5 May 2011 (UTC)

There are a number of foods that are "thermogenic": that require the body to expend a relatively high amount of calories to process them, or have other effects that elevate metabolism (see thermic effect of food). It's claimed that, once one calculates it out, some foods have a net zero calorific effect, or even a marginally negative one (celery is claimed to be negative calorie, but as the TEoF article notes, without real proof - measuring the actual net calorific value of a food is quite difficult). There is an urban legend (but I can't find a page about it, even on Snopes) that a certain fast food chain (which it's not fair for me to name with no reference at all) developed a "bun" made from a highly cellulosic material, which supposedly tasted and felt like bread, but which had few if any net calories. No-one has to date released that, but wood cellulose is used in quite a few processed food products (ref). With a bit of skill, food scientists probably could produce some highly cellulostic substance that could be used in place of simple carbohydrate food ingredients like bread and potato. Fry this with Olestra, colour it with caramel, sweeten it with xylitol and flavour it with delta-undecalactone and a dozen other weird industrial chemicals and maybe you'd get a passably edible low-calorie french fry (goodness knows, the "real" fast food fry is often so bad it barely passes for food to begin with, so it's a low bar). But it's another matter whether this would taste and feel acceptable to the consumer, and who knows what the digestive effects of eating this cousin of cavity wall insulation would be (I'll leave it to others to find out). Imagine the promotional material: "New improved Friez Zero: now with fewer horrific bowel contractions!!" -- Finlay McWalter ☻ Talk 20:18, 5 May 2011 (UTC)

Also note that, even if you could produce a tasty fake food with zero calories and no side effects, you'd still be hungry again in short order, as soon as your body noticed it didn't get the calories it craved. That is, unless a drug was included to suppress your appetite. This could be dangerous, though, in that people might then start passing out while driving, etc. StuRat (talk) 05:42, 6 May 2011 (UTC)

Incidentally, why are all the fast food fries fried in oil as opposed to baked in an oven without any oil? – b_jonas 08:35, 6 May 2011 (UTC)

Probably because they're cheaper and taste better fried. Baking also tends to burn parts that stick up. StuRat (talk) 16:15, 6 May 2011 (UTC)

If you could come up with a thermogenic additive that did not taste like much, you could imagine "offsetting" a significant amount of calories by hiding it in the bread (as opposed to trying to substitute the flavors, in the way that Coke Zero does with sugar). I wouldn't be surprised if someone comes up with something like this in the next decade. There's an obvious market for it. --98.217.71.237 (talk) 12:13, 6 May 2011 (UTC)

Suspension bridge small cables

Tamar Bridge

Golden Gate Bridge

What is the purpose of the two small cables running above the main suspension cable on some suspension bridges such as the Tamar Bridge and Golden Gate Bridge? SpinningSpark 17:48, 5 May 2011 (UTC)

Safety line for maintenance workers and/or inspectors. Side-note: possibly the best job ever if you like the outdoors and aren't afraid of heights. -RunningOnBrains^(talk) 17:52, 5 May 2011 (UTC)

Is that possible?

Can man do such things with his eyes or this image is photoshopped?--89.76.224.253 (talk) 18:19, 5 May 2011 (UTC)

That would be quite a stretch for the optic nerve. Maybe if they were glass eyeballs and he had extreme tissue elasticity. Edison (talk) 19:28, 5 May 2011 (UTC)

Applying Occam's razor to Edison's dichotomy would suggest that it's photoshoped, with a very high probability. Grandiose (me, talk, contribs) 20:25, 5 May 2011 (UTC)

But don't forget this lady. Staecker (talk) 21:41, 5 May 2011 (UTC)

With difficulty I tracked that to Kim Goodman. Also see [1]. There's no medical information about it - specifically, I doubt claims that this is due to Graves' ophthalmopathy. There's a difference between people who can pop their eyes out and people whose swelling forces their eyes to pop out "whether they can or not". Wnt (talk) 23:37, 5 May 2011 (UTC)

It's obviously photoshopped — look at the eye on the right very closely, you'll see it is feathered "over" the hand in an obvious photoshop artifact. Note also that the eyes are actually switched from their normal left/right sockets. You can see that the tear ducts are in the wrong place. It's clearly a photo of someone squeezing their upper cheeks, with the eyes moved. --Mr.98 (talk) 22:17, 5 May 2011 (UTC)

I don't want to look at disturbing photos, but I recall reading that in past centuries it was the fashion for some islanders living in the Pacific to pop their eyes out a great deal and keep them in place with small pieces of wood. Don't try this at home. 92.28.243.102 (talk) 11:35, 6 May 2011 (UTC)

. Google doesn't turn up anything about that. Red Act (talk) 16:34, 6 May 2011 (UTC)

I would like to know more about these intriguing islanders in the Pacific and their small pieces of wood. Sean.hoyland - talk 18:02, 6 May 2011 (UTC)

Boy, wood eye love to see a picture of it! Edison (talk) 18:14, 6 May 2011 (UTC)

Also, messing around with moai eyes doesn't count. Sean.hoyland - talk 18:28, 6 May 2011 (UTC)

Were each of the twelve men who walked on the moon first-born sons?

Were each of the twelve men who walked on the moon first-born sons?82.31.133.165 (talk) 20:53, 5 May 2011 (UTC)

We don't have many family details on the Apollo astronauts, but Pete Conrad had two older sisters, so your question can be answered "No", assuming that having an older sister (rather than an older brother) prevents one from being a "first-born son". Tevildo (talk) 23:47, 5 May 2011 (UTC)

According to NASA [2], of the 29 Apollo astronauts, 6 were only children, 16 were first-born children in families with more than one child, 5 were the first male child but had older sisters, and only 2 had older brothers. Of those two, neither set foot on the moon. So, it would seem to be the case that every man who walked on the moon was the oldest (or only) son in their family. Dragons flight (talk) 23:52, 5 May 2011 (UTC)

three-point adhesion

whats three-point adhesion —Preceding unsigned comment added by Kci357 (talk • contribs) 22:38, 5 May 2011 (UTC)

Three point adhesion occurs when caulk adheres not only to the two sides of a joint, but also the back. This degrades the caulk's ability to elongate, which can over time result in sealant failure. Three point adhesion can be prevented by using backer rods and bond breaker tape as needed.[3] Red Act (talk) 00:54, 6 May 2011 (UTC)

Excellent answer ! StuRat (talk) 05:32, 6 May 2011 (UTC)

Be aware that the OP is alleged to be a sock of the indef'd user Kj650 (talk · contribs · deleted contribs · logs · filter log · block user · block log), as per the ref desk talk page. ←Baseball Bugs ^{What's up, Doc?} carrots→ 20:43, 7 May 2011 (UTC)

Mechanical processes and manufacturing technology

how do mechanical processes affect and relate to manufacturing tecnology? —Preceding unsigned comment added by Aliaulakh2 (talk • contribs) 23:48, 5 May 2011 (UTC)

That looks like a homework question -- we aren't supposed to do those for people. Looie496 (talk) 00:55, 6 May 2011 (UTC)

May 6

Trash on the moon

How hard/easy is it to directly observe some of the man made objects on the lunar surface? I believe the "bases" of the LEMs are the largest of these objects? What type of telescope (magnification, focal length, etc) would be adequate to make the objects clearly recognisable? Roger (talk) 09:00, 6 May 2011 (UTC)

This recent discussion may provide some idea Wikipedia:Reference desk/Archives/Science/2011 April 29#SF "sensors" and today's technology Nil Einne (talk) 09:34, 6 May 2011 (UTC)

More from the archives I found Wikipedia:Reference desk/Archives/Science/2009 July 18#Apollo Lunar Rovers which links to [4]. Nil Einne (talk) 09:41, 6 May 2011 (UTC)

As a more recent followup to the 2009 LRO comment, that project has now advanced...see Lunar Reconnaissance Orbiter for images. Now whether that's recognizeable to an untrained eye? However, it's a good gauge for OP how much can be seen from moon orbit using dedicated instruments designed to do this, vs off-the-shelf equipment from earth. Might be some info (or at least an interesting read) at Third-party evidence for Apollo Moon landings. DMacks (talk) 09:52, 6 May 2011 (UTC)

For clarification the images available at the time were [5]. I can't find much discussion of the Apollo rovers but the Soviet ones were identified [6] Nil Einne (talk) 10:43, 6 May 2011 (UTC)

Looking at those pics, it seems that, with the exception of the foot path, the junk can be identified by being more reflective (shinier) than the surroundings. This suggests that a computer program could search for junk on the Moon by checking the brightness of every pixel. StuRat (talk) 01:38, 7 May 2011 (UTC)

See Third-party evidence for Apollo Moon landings for some photos. Bubba73 ^{You talkin' to me?} 23:23, 8 May 2011 (UTC)

Actually the easiest to observe are probably the retro-reflectors installed by the Apollo missions, any sufficiently powerful laser can be bounced off them and receive a distinctive return in the form of an abnormal spike in the light level at that wavelength. HominidMachinae (talk) 23:34, 10 May 2011 (UTC)

some disease without symptoms

hi i had heard about it twice in my life till now, it is a disease of something else i donot know but it dosent show any symptoms and body temperature rises high with weakness only this can u guess what this is.....thanx —Preceding unsigned comment added by Myownid420 (talk • contribs) 09:20, 6 May 2011 (UTC)

A rise in body temperature with weakness is itself a symptom that only a qualified doctor should be asked to diagnose. We cannot give medical advice. Cuddlyable3 (talk) 12:05, 6 May 2011 (UTC)

Fever is a symptom of numerous infections and medical conditions. You would need a doctor to perform some tests in order to work out which one. --Tango (talk) 17:43, 6 May 2011 (UTC)

Yes, a fever is a symptom. This raises the question: Is there such a thing as a disease that has no symptoms? ←Baseball Bugs ^{What's up, Doc?} carrots→ 19:05, 7 May 2011 (UTC)

If it doesn't have some negative consequence, it's not a disease. Any such consequence is a symptom. As such, a disease must have at least one symptom. — DanielLC 00:50, 8 May 2011 (UTC)

I suppose you could have a disease with no symptoms other than death, but death would still be a symptom. --Tango (talk) 01:21, 8 May 2011 (UTC)

But how could the disease cause death without screwing things up? When cells start to die, you get symptoms. Googlemeister (talk) 13:30, 9 May 2011 (UTC)

Such a thing would not be a disease because, as the name implies, a disease causes disfunction of some kind. On the other hand there are viruses and bacteria that you can contract that have no symptoms at all. It was once thought that Toxoplasma gondii was one of those, but since we've found that it can have remarkably subtle effects (including increasing the likelihood of traffic accidents, increasing intelligence and causing 'susceptibility to guilt'). HominidMachinae (talk) 20:04, 10 May 2011 (UTC)

DNA-Identification

The DNA comparison at Mass. Gen. was done with tissue samples from a sister of Osama and samples taken from the body. To my understanding you can conclude from the results that the two people were brother and sister, right? Any more conclusions which can be drawn? Is it known, exactly which DNA-analysis was performed? References? Thanks 213.169.161.199 (talk) 10:45, 6 May 2011 (UTC)

Both a sibling relationship and a parent/child relationship should feature half the chromosomes in common. However, in the case of the parent/child relationship, it should be exactly half (barring mutations and other abnormalities), whereas siblings only average half, but could theoretically vary anywhere from no chromosomes in common to 100% (although these extremes are so unlikely that probably no siblings ever had either case). So, if they share something close to half the chromosomes, but not exactly half, that's fairly conclusive they were siblings. Lower percentages in common would indicate more distant relations, like uncle/aunt. However, if you have a population with significant inbreeding, this can complicate matters, since you can no longer assume that the parents each start with a unique set of chromosomes. StuRat (talk) 16:32, 6 May 2011 (UTC)

I'm not sure but it sounds like you are confused about how meiosis and inheritance works. Because of chromosomal crossover, chromosomes are not generally inherited as discrete units (except from the X and Y chromosome for the father) and it is entirely resonable to presume a child will have no chromosomes the same as their mother (and father excluding X or Y) even barring mutations and other abnormalities. Nil Einne (talk) 17:25, 6 May 2011 (UTC)

I've seen suggestions several relatives were used. In that case presuming we're including relatives from the male side you can probably conclude is that there was no non-paternity event. Nil Einne (talk) 17:32, 6 May 2011 (UTC)

If, from all the siblings, this sister and Osama were the only children of the same mother, a further reaching conclusion could be drawn. Anybody knows, whether there was a more scientific statement of the Mass. Gen. analysis than the one from TV 5 (Boston)? 213.169.161.199 (talk) 06:48, 7 May 2011 (UTC)

Unkown Bird

Can anyone identify this Bird? http://i51.tinypic.com/21k9dep.jpg —Preceding unsigned comment added by 182.178.250.127 (talk) 12:23, 6 May 2011 (UTC)

Where? HiLo48 (talk) 12:29, 6 May 2011 (UTC)

It is indigenous to Yahoo! Answers, apparently - [7] 91.125.193.37 (talk) 12:36, 6 May 2011 (UTC)

Both the IP and the Yahoo! Answers questioner appear to be from Pakistan although I admit I was a bit surprised by this as the paper appears to have a long story on badminton and I wasn't aware that sport was followed much in Pakistan. Nil Einne (talk) 12:59, 6 May 2011 (UTC)

Yes it was mentioned in this forum post http://www.wiredpakistan.com/forums/viewtopic.php?id=17207 —Preceding unsigned comment added by 182.178.250.127 (talk) 13:33, 6 May 2011 (UTC)

(e/c) It's a kestrel of some sort. My guess is that it's a lesser kestrel, but they all look fairly similar. Matt Deres (talk) 13:39, 6 May 2011 (UTC)

lesser kestrel is mentioned as Vulnerable, so shouldn't this bird be donated to a zoo etc ? Nil Einne badminton is really popular in Pakistani schools. —Preceding unsigned comment added by 182.178.250.127 (talk) 13:43, 6 May 2011 (UTC)

astronomy question

Lets say I look at a star from the earth and it's 100 light years away, so I am seeing it as it was 100 years ago.

If I look through 10x binoculars do I see it as it was was 10 years ago? —Preceding unsigned comment added by 92.17.3.14 (talk) 14:53, 6 May 2011 (UTC)

No, you get 10 more light, but the light will still be 100 years old. Googlemeister (talk) 15:29, 6 May 2011 (UTC)

You don't get necessarily 10 times the light. The amount of light you get depends on the diameter of the main lenses of the binocular, not on its magnification. Dauto (talk) 15:49, 6 May 2011 (UTC)

Indeed. For a given size of main lens, higher magnifications will have correspondingly dimmer images at the eyepiece. TenOfAllTrades(talk) 01:11, 7 May 2011 (UTC)

(ec) :No, the light you're seeing still travelled for 100 years. It's a sort of optical illusion you're seeing through the binoculars. --TammyMoet (talk) 15:31, 6 May 2011 (UTC)

Optical illusion isn't the way I would describe it: I would just say "optics" (no illusion involved)! We have an article on magnification, and a brief section on telescopic magnification (as it generally applies to binoculars); and of course, our binoculars article describes in detail the specifics of a binocular optical system. Note in particular the prismatic "flip" to make the image appear right-sided-up, unlike a straight telescope with equivalent magnification. Nimur (talk) 18:13, 6 May 2011 (UTC)

Yes you're right, I only thought while I was driving that the word I was looking for was "manipulation" rather than "illusion". --TammyMoet (talk) 19:00, 6 May 2011 (UTC)

Interestingly, this is the third time I've seen someone express this misconception. I wonder how common it is, and where it comes from? thx1138 (talk) 19:29, 6 May 2011 (UTC)

Well, the image formed by a conventional binocular optical system is technically called a virtual image. Perhaps you've heard this terminology, and might have conflated "virtual" with "illusory"? Would it seem less like an optical illusion, if the binocular could project its image on a screen (like, for example, a Newtonian telescope can do?) Ultimately this boils down to mostly a matter of semantics; everything we visually perceive is an "illusion" of some form or the other; the only question is whether the "rays" converge at a specific focal plane, when analyzed via a geometric optics treatment. Nimur (talk) 00:36, 7 May 2011 (UTC)

Sorry, I meant the misconception in the original question, that telescopes see light earlier than it reaches the naked eye. thx1138 (talk) 19:20, 9 May 2011 (UTC)

Current state of photovoltaics in Europe and the world

Where can I find an extensive report about the current state of the photovoltaic industry in the world? Thanks. --Belchman (talk) 16:26, 6 May 2011 (UTC)

A Google search for "current state of the photovoltaic industry in the world" finds this as the second hit. Looie496 (talk) 17:34, 6 May 2011 (UTC)

Thanks, though I'd need something less technically oriented and more economically-oriented, if that makes sense... --Belchman (talk) 20:46, 6 May 2011 (UTC)

Metal Gear

Is it even possible for something like metal gear rex or ray from the metal gear solid series to even exist. --93.107.220.94 (talk) 18:55, 6 May 2011 (UTC)

Are you talking about Metal_Gear_(weapon)#Metal_Gear_REX? Walking tanks with heavy armor and railguns may not be especially plausible (or worthwhile) with current technology, but I don't see anything at a glance that would make such a thing impossible. Is there some specific feature of this fictional machine that seems impossible to you? SemanticMantis (talk) 19:12, 6 May 2011 (UTC)

I'm pretty sure it can't fire off a railgun that powerful without the recoil sending it through the ground, although I'm not sure if they ever say that doesn't happen. It would be pretty pointless to put a weapon like that on a walking tank, since you could put it literally anywhere and have the same effect. I'm not sure if a railgun can be made efficient enough to not just vaporize the nuke when it fires, and I'm not sure you could make a nuke that would survive that. I think the acceleration required would be enough to set off any explosives. Everything besides the railgun is probably not worth building, but you still could. — DanielLC 21:29, 7 May 2011 (UTC)

railguns are actually very efficient in terms of recoil, you could accelerate small bullets to relativistic speeds without enough recoil for a tank-sized hunk of metal to feel it. On the other hand that same abundant mass that means recoil is the least of your worries means that ground pressure is your biggest concern. As the Russians found out with the Czar Tank, anything that relies on small surfaces to rest on would have serious issues in any practical battlefield situation. Think of it this way, as height increases, weight increases exponentially, any "walker" is militarily impractical for that reason. HominidMachinae (talk) 21:25, 10 May 2011 (UTC)

worker ants

Are the worker ants in a single colony usually genetically identical to each other? Googlemeister (talk) 19:20, 6 May 2011 (UTC)

If the colony has one queen then yes. Some species have several queens in a colony so they'll be different 82.43.89.63 (talk) 19:44, 6 May 2011 (UTC)

No, they aren't. Workers come from fertilized eggs and are diploid. See haplodiploid sex-determination system. An exception is Wasmannia auropunctata. Sean.hoyland - talk 20:05, 6 May 2011 (UTC)

(EC) No, they are not clones, contrary to the IP above. See Haplo-diploid_sex-determination_system#Relatedness_ratios_in_haplodiploid. In short, sister worker-ants share 75% of their genes. SemanticMantis (talk) 20:08, 6 May 2011 (UTC)

Also bear in mind that mating with multiple males is common which adds further complexity to their internal make up even if there is only one queen. Sean.hoyland - talk 20:22, 6 May 2011 (UTC)

Relativity vs quantum mechanics

I got an impression that Einstein's relativity is more God-friendly (that is more favorable to intelligent design conjectures behind some phenomena) than quantum mechanics and is generally more flexible than quantum mechanics, allowing such things as wormholes etc. Is it right? I also think that quantum mechanics is less verified than the relativity theory and because of likely flaws can not be unified with relativity within the unified field theory framework at all. --89.76.224.253 (talk) 20:25, 6 May 2011 (UTC)

Your question appears to depend on a subjective view of what is "God-friendly". Since discussions about God are not really a part of science, I'm not sure we can give you a good answer. Perhaps if you gave a more concrete explanation of what you mean by "God-friendly", we could address whether relativity / quantum mechanics exhibits those characteristics. In general though, both theories expand our understanding of the physical laws that appear to govern our universe. As the number of things that science can explain increases, the number of things potentially attributable to "God" would tend to decrease. In all probability there will always be things beyond the limits of scientific understanding that might be attributed to "God", but placing God solely in the role of filling in the gaps would often lead to a very different view of God than that popularized by most religions. Dragons flight (talk) 20:38, 6 May 2011 (UTC)

The problem in trying to compare GR and QM this way is that they deal with really quite radically different domains of physics, which only converge in a few places. They are both highly successful theories — this is why it is so striking that they have as of yet still resisted unification, because it is really unthinkable that either are extremely wrong. It is not really an either/or situation — they are both about the same level of "verified", even in their weirder aspects. There are loads and loads of experimental verifications of both of them at this point. I don't see how either are more "God-friendly", frankly. You can interpret either in "God-friendly" ways, it's all in how you define "God-friendly." --Mr.98 (talk) 20:51, 6 May 2011 (UTC)

QM allows God to gamble. Count Iblis (talk) 21:32, 6 May 2011 (UTC)

For readers who don't understand this remark (which shouldn't be taken too literally), see Bohr–Einstein debates#The quantum revolution. Red Act (talk) 22:00, 6 May 2011 (UTC)

Also, it's only a certain interpretation. The many worlds interpretation is deterministic. — DanielLC 20:58, 7 May 2011 (UTC)

Ralativity allowing such things as wormholes and QM allowing MWI , thanks —Preceding unsigned comment added by 87.68.158.147 (talk) 07:26, 7 May 2011 (UTC)

From your examples, I guess you're looking for ways that a large supernatural being could hide out somewhere and not be detectible through telescopes, like hanging out at the other end of a worm hole, or in a nearby MWI-style universe? Conceptions of God vary widely, but God in Abrahamic religions is largely imagined to be transcendent, which is a poorly-defined mechanism by which god can interact with physical existence without existing within it. If you're looking for a physical mechanism by which transcendence could work, it doesn't seem to me that either relativity or quantum mechanics would provide such a mechanism. Both branches of physics describe the orderly ways that physical existence behaves. There is no mechanism in either for physical existence behaving in an unexpected way. Both branches make specific predictions about how physical existence will progress, either in a deterministic sense in the case of relativity, or in a probabilistic sense in the case of quantum mechanics. If anything outside of physical existence were to affect physical existence, that would result in the predictions of either relativity or quantum mechanics being wrong. I.e., transcendence is inconsistent with either branch of physics. Red Act (talk) 08:53, 7 May 2011 (UTC)

Of course those of us who believe that God "is all, and in all" see no dichotomy between quantum theories and Einsteinian theories. --TammyMoet (talk) 09:17, 7 May 2011 (UTC)

God can't hang out in a nearby MWI-style universe. How near they are is just how similar they are. If he was in that universe and not this one, they'd be astronomically far away. Also, you can only effect your own universe and those in your immediate vicinity (or just yours, depending on how you define "universe"). — DanielLC 20:58, 7 May 2011 (UTC)

The theory is that God is "outside of time", hence He is in some "dimension" that humans cannot observe, but God can observe everything, all at once. ←Baseball Bugs ^{What's up, Doc?} carrots→ 21:08, 7 May 2011 (UTC)

My point is that an MWI-style universe would not allow this. Also, a dimension is essentially a direction. Please don't use it to mean an alternate reality. — DanielLC 00:44, 8 May 2011 (UTC)

May 7

Ismail Ibn Sharif

According to his Wikipedia biography, Moulay Ismaïl is alleged to have fathered 889 children. This is widely considered the record number of offspring for any man throughout history that can be verified. It is thought that Ismaïl would have had to copulate with an average of 1.2 women per day over 60 years to achieve that number of children.

Semen tend to be thinner after continuous sex. How did he fathered so many children, I mean how is it biologically possible? --HoulGhostjj (talk) 01:04, 7 May 2011 (UTC)

How did you get 1.2 women per day ? I get 15 women per year. And, of course, they don't always get pregnant the first time, so, if you figure maybe 10 times each, that only requires sex 150 times a year. If you increased that in his prime and decreased it later, it seems possible. StuRat (talk) 05:18, 7 May 2011 (UTC)

Wilt Chamberlain claimed to have slept with 20,000+ women, so if this were true (he kept score?) and Ismaïl were his match, it would have taken less than 1 pregnancy per 20 hops in the hay. Stu, you get 15 per year? I bow to your awesome studliness. Clarityfiend (talk) 06:18, 7 May 2011 (UTC)

@ StuRat "And, of course, they don't get pregnant the first time..." Sorry, am I being a bit thick here, what does that mean? Are you suggesting that women don't get pregnant from their first sexual act? Richard Avery (talk) 07:25, 7 May 2011 (UTC)

I'm pretty sure he just means that copulation does not have a 100% chance of producing live birth, and it would be sloppy to estimate the math by assuming that.SemanticMantis (talk) 14:15, 7 May 2011 (UTC)

Yes, that's what I meant. I've added "always" to my previous post to clarify it. StuRat (talk) 18:53, 7 May 2011 (UTC)

Uh, hang on here... 889 children... with 889 women available, at 1 per day, you could accomplish that in less than 3 years. ←Baseball Bugs ^{What's up, Doc?} carrots→ 20:20, 7 May 2011 (UTC)

Not every act of copulation results in impregnation. --Jayron32 20:23, 7 May 2011 (UTC)

If he was exceptionally virile, and the 889 women were sufficiently fertile, it wouldn't take very long. I'm trying to figure out where the 60 years came from. ←Baseball Bugs ^{What's up, Doc?} carrots→ 20:31, 7 May 2011 (UTC)

Well, assuming he has no idea over the fecundity of the individual women, for large sample sizes as this, the numbers should fall back to the statistical averages. That is, if we know, on average, how many days per month a woman may become pregnant from an act of copulation, AND what percentage of copulation acts which occur during the proper window of time actually result in pregnancy, we could extrapolate an ideal number of sexual acts needed to produce 889 children. While, again hypothetically, the minimum under ideal conditions could be less than 889 acts (considering that 1/40 births are twins, we can safely knock 20 or so sex acts off of our minumum number), there are factors which will stretch it to be somewhat longer. --Jayron32 21:17, 7 May 2011 (UTC)

Somewhat longer, maybe, but it shouldn't necessarily require anywhere near 40 years (as the article indicates) or 60 (as someone said above). It depends in part, of course, on how many "wives" he had. And as far as I know, the female monthly cycle was well-known to the ancients, i.e. they knew when a woman was most likely to be fertile. They didn't understand the mechanism, of course, but they had the cycle pretty well figured out from observation. Supposing the time period is 40 years rather than 60, that's still only 22-23 pregnancies a year, or about 2 a month, which certainly seems do-able. ←Baseball Bugs ^{What's up, Doc?} carrots→ 21:25, 7 May 2011 (UTC)

It's the child support that isn't do-able. Googlemeister (talk) 13:28, 9 May 2011 (UTC)

Inch of water

At least one of the conversions in the inch of water article (the one to cmH2O) seems to be way off. This puts all the rest of these figures, and by extension the others added by the same editors to other articles, into question. Can someone check these, please? -- Chronulator (talk) 03:00, 7 May 2011 (UTC)

Fixed. It was a simple mistake. they used the inverse of the correct conversion factor. Dauto (talk) 03:22, 7 May 2011 (UTC)

I need to clean a disgusting sink: question about bleach and ammonia...

So... I have to clean a sink that appears to be ridden with mold, it is my friend's sink. It is to my understanding that if you mix ammonia and bleach, you create ... chlorine gas I believe. My fear rests in the fact that I know at one point my friend may have tried to clean said sink with ammonia, and my current plan is to clean it with bleach. So.. for you science guys, some questions:

1. If ammonia based soap was ever used on this sink, is there any chance some ammonia molecules may still be resting amongst the very dense mold in the sink, thus making the use of bleach on the mess a deadly choice?

2. If yes, does anyone have any better solutions as to how I should approach cleaning this disgusting sink.

PS: I'm not sure the filth is entirely mold, much of it appears to be fungus like... is mole a fungus?

Thanks for your help. I am new with posting here sorry for any lack of etiquette. —Preceding unsigned comment added by 71.204.172.247 (talk) 07:13, 7 May 2011 (UTC)

I'd stick to the bleach if I were you. If you're unhappy that the mould might have trapped some ammonia molecules, flush the sink well with (boiling) hot water. My plan of attack would be: Open the windows and doors wide. Put the plug in the sink. Fill sink with hot water and let stand for a few minutes. Pull the plug and let it drain. Repeat but this time add bleach. If you're worried about the presence of ammonia, only use a little bleach. Pull the plug and now get to work with a scourer, and you should find the grot comes off easily. By the way, if the sink is enamel you might have to get a specialist enamel cleaner as the bleach may remove the glaze. --TammyMoet (talk) 07:53, 7 May 2011 (UTC)

And in answer to your last question, yes the word mould (I use the UK spelling) is used to refer to a range of fungi with certain living habits. --ColinFine (talk) 09:50, 7 May 2011 (UTC)

I can't see a significant amount of ammonia being retained. The bleach fumes themselves will pose more of a hazard than any miniscule amount of chlorine gas produced. Whenever using bleach, open the windows and put fans in them, apply the bleach quickly, then leave the area. Better yet, leave the residence for a few hours (time the use of the bleach for just before you planned to leave anyway). StuRat (talk) 18:49, 7 May 2011 (UTC)

In any case, Chlorine gas is much denser then air, so unless there is a lot going on to stir the stuff up, it should go down the drain. Googlemeister (talk) 13:26, 9 May 2011 (UTC)

Black body radiation question

what is the absorption power of a perfect blackbody? (four options)

1. zero
2. infinity
3. 1
4. 0.5 —Preceding unsigned comment added by 116.71.175.198 (talk) 09:09, 7 May 2011 (UTC)

Please do your own homework.

Welcome to the Wikipedia Reference Desk. Your question appears to be a homework question. I apologize if this is a misinterpretation, but it is our aim here not to do people's homework for them, but to merely aid them in doing it themselves. Letting someone else do your homework does not help you learn nearly as much as doing it yourself. Please attempt to solve the problem or answer the question yourself first. If you need help with a specific part of your homework, feel free to tell us where you are stuck and ask for help. If you need help grasping the concept of a problem, by all means let us know.

You may find the Black body article helpful. Red Act (talk) 09:38, 7 May 2011 (UTC)

And Attenuation coefficient too, although I'm not sure if "absorption power" is exactly the same thing. I kind of feel bad that both of those articles taken together don't really have enough information to answer this question as it is stated. 99.39.5.103 (talk) 23:56, 7 May 2011 (UTC)

Yeah, that is kind of pathetic that Wikipedia articles alone don't seem to be adequate to answer this simple question. The correct term appears to be absorptive power, and while there is a redirect for that, it goes to an article that doesn't define that term. Here is an external link that tells you what you need to know.[8] Unfortunately, the phrase "absorptive power" appears to also have a different definition, other than the one used when discussing black bodies.[9] Red Act (talk) 01:49, 8 May 2011 (UTC)

What species is this frog?

--Inspector (talk) 11:13, 7 May 2011 (UTC)

Where was it ? It looks like Kaloula pulchra. Sean.hoyland - talk 15:28, 7 May 2011 (UTC)

Ah, I see you are in the PRC. I see those in Thailand very often, or something very similar. The Kukri vipers in my garden seem to like them. Sean.hoyland - talk 15:37, 7 May 2011 (UTC)

No wonder. They're nice and plump. ←Baseball Bugs ^{What's up, Doc?} carrots→ 18:59, 7 May 2011 (UTC)

Laser as a weapon

I'm sure someone had this idea before, but, why wasn't it implemented? It might not kill, but blinding is a huge blow on enemy forces. Quest09 (talk) 12:39, 7 May 2011 (UTC)

In what way would a laser be better than a gun? --Tango (talk) 12:59, 7 May 2011 (UTC)

See Laser weapon and Protocol on Blinding Laser Weapons. PrimeHunter (talk) 13:06, 7 May 2011 (UTC)

A gun shoots one bullet at one place at one time. A laser could cover a broad area without pause. Quest09 (talk) 15:07, 7 May 2011 (UTC)

I agree, but then you are presumably thinking about air to ground or space to ground operations. So, from a geostationary satellite, you could easily take out targets in North Korea and then immediately switch to Libya or Iran if the need were to arise. Count Iblis (talk) 15:22, 7 May 2011 (UTC)

Or put a laser in a unmanned aircraft, breaking havoc among enemy troops, putting moral and legal issues by side, of course. Quest09 (talk) 15:36, 7 May 2011 (UTC)

A rapid fire gun would also work... --Tango (talk) 19:53, 7 May 2011 (UTC)

Some reasons not to use them:

1) They really couldn't be used as a wide angle, as the brightness would then decrease too much to be useful. Lasers are only effective as a narrow beam. (I don't think it would even meet the definition of a laser if it wasn't in a narrow beam.)

2) Unlike with a gun (barring tracer rounds), firing a laser gives away the position of the shooter.

3) Any new technology tends to cause objections as being "cruel and unusual". The unusual is true, of course, as it's not the usual weapon used. But, any new way to kill or injure people tends also to be seen as more cruel than the older methods.

4) Lasers are weather-dependent, in that their energy is absorbed on foggy days. Smoke on the battlefield would also interfere with their operation.

5) If they worked, soon both sides would use them, and after the war, we would all have large numbers of blind soldiers going home. (Although I suppose an argument could be made for this making the cost of war more apparent, and thus preventing future wars.)

6) Countermeasures could be developed, such as simple sunglasses, or, for brighter lasers, using a camera and video display rather than looking directly at the enemy. StuRat (talk) 18:44, 7 May 2011 (UTC)

As PrimeHunter linked above, it's illegal. Additionally, to date, a major problem has been the lack of portable energy sources that are powerful enough. Also the bad guys would issue mirrored sunglasses to their troops, and they would laugh scornfully at our tech. Comet Tuttle (talk) 18:55, 7 May 2011 (UTC)

It has been implemented. US navy destroyers are starting to mount powerful lasers for less than lethal use. Although they can kill a human being and are actually lethal, they're incredibly accurate and are used for destroying the engines of small boats when causing casualties is undesireable.[10] They're also working on a laser replacement for the Phalanx CIWS to shoot down anti-ship missiles and aircraft[11].

StuRat you claim lasers are visibible, unlike bullets. They aren't. A "laser gun" would be less visibiel than a rifle or whatever because there is no loud report or muzzle flash.--92.251.146.168 (talk) 19:23, 7 May 2011 (UTC)

You seem to have confused "visible" with "audible". And our ears aren't nearly as precise at locating objects as our eyes, so a loud sound isn't likely to give away your position, especially on a noisy battlefield. StuRat (talk) 06:51, 8 May 2011 (UTC)

A photosensor on a missile could easily detect and home in on a laser, if it were nearby. Goggles could shield the eyes, either by blocking the wavelengths used for such blinding attacks, or by being instant darkening like welding facemasks. Soldiers without access to such high tech could go pirate and wear a patch over one eye, so they could fight after the attack was over. A blinding attack would likely be considered a war crime, and the other side would also use it. Edison (talk) 19:44, 7 May 2011 (UTC)

A laser is invisible unless it is pointed directly at you (unless there is some mist or smoke scattering it). --Tango (talk) 19:53, 7 May 2011 (UTC)

And smoke/dust are quite common on a battlefield. Also, at night, I suspect that the particulate matter in even "clean" air would be enough to make such lasers visible. StuRat (talk) 06:48, 8 May 2011 (UTC)

I think any laser powerful enough to be used as a weapon would have enough scattered normally to see, providing it uses a visible wavelength, which it probably wouldn't. Atomic Rockets has some interesting things about laser pistols and laser cannons. — DanielLC 20:53, 7 May 2011 (UTC)

In WW2, both sides were prepared for poison gas attacks by the other side, but I haven't read of either side using such weapons. Each side feared the inevitable retribution. Ditto for blinding the enemy with lasers, most likely. Edison (talk) 21:02, 8 May 2011 (UTC)

There are invisible lasers on the battlefield already. I think those are infrared. If the beam was visible it would be very bad news for the soldiers trying to designate a target, especially at night. I believe that even though they are invisible, infrared lasers can still blind if they are powerful enough. Vespine (talk) 23:59, 8 May 2011 (UTC)

If you were going for blinding, wouldn't UV be better for your laser then IR? Googlemeister (talk) 13:23, 9 May 2011 (UTC)

If bin Laden had a medical need for dialysis

How could he have got treatment for 6 years at home? That must have been a huge annoyance ... —Preceding unsigned comment added by 212.169.191.38 (talk) 15:04, 7 May 2011 (UTC)

No evidence of medical equipment was found at his home. Also note that Al Zawahiri used to be a surgeon, so he could have helped him out when they were together earlier. But the evidence suggests that Bin Laden did not have any kidney problems. Count Iblis (talk) 15:09, 7 May 2011 (UTC)

Snopes has an article on that: [12]. The status is 'undetermined.' Maybe he got some treatment in the nearby military infirmary. THAT would be funny. Quest09 (talk) 15:15, 7 May 2011 (UTC)

Some forms of renal impairment indicating dialysis are temporary (I'm not sure but I think about 10% of people treated with dialysis eventually go off it--can anyone find that number?), and a kidney transplant can solve those which are not. Bin Laden had a large pool of potential donors. I think the chance that someone with that many kids and access to cash would not get a kidney transplant are very slim. 99.39.5.103 (talk) 23:02, 7 May 2011 (UTC)

The problem here is also not the transplant, but getting the logistics right without getting caught. If you believed he had a kidney problem, the trick here was to watch out for nephrologists, people buying dialysis machines and the like. However, if the CIA followed this lead, it went nowhere, since this need for dialysis was bogus. More about it from the nytimes: "Contrary to a widely-held belief that Bin Laden was on dialysis to treat a kidney ailment, Pakistani investigators said last week that his youngest wife told them he was healthy. “He was neither weak nor frail,” one of the investigator quoted the wife as saying. She told them, they said, that Bin Laden had recovered from two kidney operations a decade or more ago."

Inactive ingredients in medicines

Looking at the fine print of drug packages, there are a lot of inactive ingredients, aka nonmedicinal ingredients.

Here for an example is the list for a medication used to lower blood pressure and for other purposes. (This medication) "is available as tablets for oral administration, containing 40 mg, 80 mg, 160 mg or 320 mg of valsartan. The inactive ingredients of the tablets are colloidal silicon dioxide, crospovidone, hydroxypropyl methylcellulose, iron oxides (yellow, black and/or red), magnesium stearate, microcrystalline cellulose, polyethylene glycol, and titanium dioxide."

From the labelling I learn that the iron oxides are used to colour the tablets so different strengths are different colours.

Questions: Are all these ingredients necessary? Could they just mix the drug in with, say, cornstarch and press it into tablets?

How much of the cost (roughly) of pills would be for the inactives?

Is a list available of inactive ingredients telling what purpose they serve?

Thanks, Wanderer57 (talk) 16:09, 7 May 2011 (UTC)

Many of the ingredients are there as part of the pills time release technology. One of the conundrums of medicine is Pharmacokinetics, that is basically how a drug is metabolised in the body, and most importantly for our discussion how fast it is metabolized. For many drugs, the body basically digests them faster than they can be used; meaning that you either have to take a massive overdose to ensure that enough gets to where it needs to (a dangerous solution) or you need to take a lot of little doses all day long (inconvenient, especially for those times when you are asleep). The inactive ingredients you listed are compounded with the pill in such a way as to release the drug slowly into your blood stream, providing a slow, continuous stream of medication without having to take pills like every hour or half hour. This is vital to how the medication works; and though regulation requires any non-physiologically active substance to be labeled "inactive", that doesn't mean they aren't vital to the pills formulation. --Jayron32 16:16, 7 May 2011 (UTC)

Another use of inactives in some tablets is to prevent you tasting the active ingredient - e.g Zopiclone - the active ingredient is mixed up, and made into small "centres", these are then surrounded by a layer of inactives, and maybe even a sugar coat over the top. Believe me, you would not be able to swallow one without the coating - bitter - does not ever start to describe it (I know, I've made it)!  Ronhjones  ^(Talk) 16:45, 7 May 2011 (UTC)

Most of the cost of expensive medications cover the research, not the production of the drug. – b_jonas 17:15, 7 May 2011 (UTC)

Agreed, productions costs are typically tiny in comparison. One funny ingredient is silicon dioxide, which is essentially sand. I suspect that this is used as filler, to make the pill large enough to handle easily. The titanium dioxide, on the other hand, is white coloring. I suspect that this is combined with the other colors to make pastels. StuRat (talk) 18:30, 7 May 2011 (UTC)

Pharmaceutical executive salaries, bonuses, and other compensation probably exceed the actual cost of drug production by now, and if they continue to increase at the rate they have over the past 30 years, they will overtake research costs, too. 99.39.5.103 (talk) 23:07, 7 May 2011 (UTC)

Thank you all. I am once again hugely impressed by the people at the Reference Desk.

Wanderer57 (talk) 20:18, 7 May 2011 (UTC)

about tunnelng effect

why classical particles do not shows tunneling effect?

Because they are not allowed to have negative kinetic energy since that would mean an imaginary speed (or negative mass) which make no sense classically. Dauto (talk) 18:10, 7 May 2011 (UTC)

Genetic bottleneck due to Great Famine of 1315-1317?

Can one detect the crash of the population due to the Great Famine of 1315–1317 and/or the following Black Death epidemics using the genetic diversity of the population of Europe today? Also, are the descendants of the survivors more susceptible to becoming obese? Count Iblis (talk) 18:34, 7 May 2011 (UTC)

How do you propose to do a comparative study involving the non-survivors and their descendants? TenOfAllTrades(talk) 18:41, 7 May 2011 (UTC)

I would be very surprised to see a population bottleneck from any of these events. While such bottlenecks do occur, as in the genetic history of indigenous peoples of the Americas or in certain town with unusual characteristics like Cândido Godói, I don't think that any famine or plague has been bad enough to create a truly small population size. Also bear in mind that humans have an effective population size which is much smaller than the total population size. If the plague kills half your town, you're more likely to go over to the next town for a mate, and thereby inbreeding is decreased and genetic diversity is maintained anyway.

The effect of this and other natural selection events on obesity is probably fairly large, but likely has gone on over many millions of years. Selection of symbiotic intestinal bacteria may also be important; also I suspect epigenetic effects. The best way to study this effect would not be by trying to find genetic traces in live individuals dozens of generations later, but by testing corpses from known famines that have been stored in crypts, catacombs, or other mass graves. Wnt (talk) 20:10, 7 May 2011 (UTC)

I seem to remember that it only takes hundreds, not thousands, of fertile mammals to avoid a dangerous bottleneck, assuming some kind of prevention of inbreeding. The inbreeding of aristocratic classes is usually much worse than any disease or natural disaster. Relatively isolated Polynesian island populations in the low tens of thousands without specific taboos against inbreeding remained viable for ~25,000 years in some cases. 99.39.5.103 (talk) 23:13, 7 May 2011 (UTC)

I see, so there is no bottleneck. I still wonder if people of European descent are more susceptable of becoming obese than the average African. My not so scientific personal observation suggests that this may be the case. I know quite a few people (all Europeans) who seem to survive on very little food. Count Iblis (talk) 23:41, 8 May 2011 (UTC)

Are there any known substances that are harder than diamond?

--75.40.204.106 (talk) 19:37, 7 May 2011 (UTC)

A politician's skull? ←Baseball Bugs ^{What's up, Doc?} carrots→ 19:39, 7 May 2011 (UTC)

The Mohs scale of mineral hardness says that Aggregated diamond nanorods are harder than regular diamonds. They're still diamonds, technically, but a form of diamond that is not at all found in nature ("nanodiamonds"). They are apparently the hardest known substance. --Mr.98 (talk) 19:44, 7 May 2011 (UTC)

Well that may need to be updated: Wurtzite boron nitride can be 20% harder than diamond at some compression pressures.[13] Pure lonsdaleite would be 58% harder than diamond if someone could figure out how to synthesize it (although it's also a carbon crystal, which is probably how some people define diamond) but natural lonsdaleite has impurities putting it at 7-8 on the Mohs scale. 99.39.5.103 (talk) 23:24, 7 May 2011 (UTC)

My old chemistry book said that BN was harder than diamond. Bubba73 ^{You talkin' to me?} 23:26, 8 May 2011 (UTC)

I used to hear that Titanium was the strongest metal, and fittingly the sub that explored the Titanic wreckage was encased in a titanium alloy. Are diamonds harder than titanium? ←Baseball Bugs ^{What's up, Doc?} carrots→ 23:40, 8 May 2011 (UTC)

A lot harder. Metals in general have properties like ductility, as determined by their electronic makeup (see sea of electrons model) such that even the hardest known metal is likely to be softer than a whole host of other materials. --Jayron32 01:01, 9 May 2011 (UTC)

I see. So, am I supposing correctly, that while diamonds are harder, their properties vs. the proterties of metals, would make diamond crystal an impractical submarine hull? (Never mind the cost.) ←Baseball Bugs ^{What's up, Doc?} carrots→ 01:08, 9 May 2011 (UTC)

Yes. Diamonds are harder than metals, but they are also more brittle, and less able to be "worked" into a variety of shapes. You can't bend or mold or diecast diamonds, which makes construction with them nearly impossible. Plus, though hard, diamonds are not terribly tough, in terms of being able to survive an impact. Hardness is merely a measure of how well it resists scratching, NOT how well it resists, say, a sudden impact of great force. Diamond#Hardness discusses this in the last paragraph, where it notes that for a gemstone, diamonds are particularly tough, but being tough for a gemstone is kinda like being hard for a metal; most metals are probably tougher than diamond, even if most metals are not anywhere near as hard. --Jayron32 01:13, 9 May 2011 (UTC)

The key point there would seem to be the brittleness factor. The fact that metals can "give" works in their favor for this scenario. Provided they don't "give" too much. ←Baseball Bugs ^{What's up, Doc?} carrots→ 01:49, 9 May 2011 (UTC)

It is important to avoid confusing strength with hardness. Dauto (talk) 13:45, 9 May 2011 (UTC)

bcc-carbon may be harder, but at this point in time there is not much around on the earth. Graeme Bartlett (talk) 03:04, 9 May 2011 (UTC)

Frame Dragging/Conservation of energy/General Relativity

This whole gravity probe B stuff has got me wondering a few things that i believe are either a consequence of my limited understanding of the matter.

So if i understand correctly, frame dragging occurs because of the rotation of the object, which rotates the dimple in space-time. First just a general question is: Where does the force come from for gravity on the object? is the energy taken from the thing causing the dimple in space time? How exactly does this process occur? In other words, what is happening (speaking in terms of energy) when the probe is doing it's thing?

if the energy is taken from the earth, what form is it leaving the earth in and how does it transfer to the object? or is any energy even coming from the earth, and the object is merely "sliding down the dimple"? (although this wouldn't seem to make sense to the rest of physics)

All these questions may be fundamental but i can't seem to wrap my head around this stuff.

Thanks 68.49.224.135 (talk) 22:07, 7 May 2011 (UTC)

I'm not sure, but you might be able to think of the source as the same gravitational potential energy from the distance (altitude of the object) but the ordinary Newtonian conservation law is violated by GR because frame dragging doesn't change that distance so there is no transfer. On second thought, the orbiting object drags the larger rotating object's frame as much as it gets dragged by the larger rotating object, but the extent to which the larger object gets effected is proportional to the mass ratio, so the energy might come from the rotation and is conserved by torque: a tiny amount on the smaller orbiting object, and a much more minuscule amount on the larger rotating object. I hope someone who knows for sure will help me out here. 99.39.5.103 (talk) 23:43, 7 May 2011 (UTC)

There is no need for a source of energy, since the probe is not spinning up (or down). The spin is precessing which means it is changing direction. Dauto (talk)

May 8

Do spherical mirrors produce a sphere inversion?

I've been puzzling at this today... and keep running up against my mental limitations.

Do spherical mirrors produce a sphere inversion? Namely does $(r-p)(r+i)=rr$?

By sphere inversion I mean a three dimensional generalisation of a circle inversion like in this video of the inside of the outside of a horse.

I tried to solve the equation with $1/p+1/i=2/r$ but got something absurd for an answer. I'm still so confused about optics.

Yet looking at lensmaker's equation suggests that I'm not entirely incorrect since I see this bugger: $x_{1}x_{2}=f^{2},\!$

Could somebody please help clear up my confused thinking?

-Craig Pemberton 04:48, 8 May 2011 (UTC)

The equation you should be trying to get to is $(r+p)(r+i)=rr$ (remember that i is negative for a virtual image). It would be really cool if that worked, but alas, the answer to your question is no. It's possible to get to the equation $(p-f)(i-f)=ff$, though. Dauto (talk) 13:04, 8 May 2011 (UTC)

Where to obtain a HyperSim card?

(I won't trust eBay until they have phone support for all)

I brought home a Softbank 920p from Japan, and the phone and its features (like the camera) stopped working a few months later. (Why not immediately?)

I was told there was a Hyper-Sim card, but none at Best Buy.

Froogle.com only shows Ebay hits, but I cannot trust that site after some harsh experiences.

Where are any other reputable sites that sell Hypersim cards? --70.179.169.115 (talk) 05:22, 8 May 2011 (UTC)

I recommend you move this post to the Computer Ref Desk. StuRat (talk) 06:40, 8 May 2011 (UTC)

Oops, 4got about that section. Copying there now. —Preceding unsigned comment added by 70.179.169.115 (talk) 06:58, 8 May 2011 (UTC)

Cost of panels per square mile, and how many needed to power Earth?

Ok, look here: http://i.imgur.com/j9wrB.jpg

Now, how much $ are they per square mile, and how many square miles are needed to power the planet?

Next question: How many square miles are needed Just to shut down all the coal, oil and gas power plants (rather, all "dirty" power plants) on Earth?

Moreover, this is assuming how many % efficiency? (Then if the efficiency is doubled by 2030, would that halve the costs, or is there a more complex formula than that?) --70.179.169.115 (talk) 06:57, 8 May 2011 (UTC)

Before you get too excited about this, be aware that there isn't enough raw material on earth to make that many solar panels (pure silicon panels are too inefficient). Additionally making that many panels (assuming you could get raw materials) is most definitely not carbon dioxide free. Today, making a solar panel costs more energy than you get back for more than 10 years, plus there would be lots of pollution (not just CO2) in mining the necessary materials, transporting them, building infrastructure, etc etc. IMO photovoltaics (solar panels) is a dead end technology. Look at solar thermal instead. And finally doubling the efficiency is pretty much impossible. The only way to get a higher efficiency with a solar panel is what they call multijunction solar cells but they are extremely expensive and use exotic materials which for sure could never be done in quantity. Ariel. (talk) 00:36, 9 May 2011 (UTC)

This is somewhat of a red herring - for mass production of solar power to replace existing power plants, solar thermal energy would be more efficient. Isolated solar panels are most useful for providing decentralized power, especially in remote places. Wnt (talk) 06:24, 9 May 2011 (UTC)

where to get zsm 5 catalyst in india for my chemistry projectWickyjazz (talk) 07:41, 8 May 2011 (UTC)

pls help me out finding it as soon as possible it would be better if u tell me a place in north India near uttar pradesh

This is not really the place for such queries, but try browsing through this directory [14]. Usually each site listed in the directory requires you send a product enquiry under the correct category. Plasmic Physics (talk) 13:27, 8 May 2011 (UTC)

Blood test for CJD and donating blood/plasma

When it comes to donating plasma, why do they put up a blanket prohibition to anyone who's been to Europe in the 80s? Why can't they just say, "If you've been to Europe during these years, please get your blood tested and proved that there is no evidence of CJD."

So why can't a simple blood test determine whether it's safe to donate my blood/plasma? What kind of new tech innovations would be needed in blood-testing to make this determination? --70.179.169.115 (talk) 07:47, 8 May 2011 (UTC)

The short answer is "because there isn't one yet." See this BBC article, which perhaps might be usefully incorporated into our article at some stage. If the trials of the test described prove successful and the technique is approved by the various regulatory authorities, screening of donated blood will become possible - whether it's adopted is a political rather than a medical decision. Tevildo (talk) 11:10, 8 May 2011 (UTC)

Conversely in the UK they don't let you give blood if you've recently been in the US (except maybe Hawaii) over the last 28 days, in case you have pre-symptomatic West Nile Disease.(ref) Strictly the UK guidelines apply to the high-risk WND period, but they often just make it a blanket 28 days.(ref). The Republic of Ireland applies a similar restriction for people who've been to the US and Canada, and also applies a restriction similar to the US one on people who've been to the UK.(ref) The UK prohibits donations from people who have family members that have developed vCJD.(ref). If the UK rules were applied in the US it would eliminate all donors; if the US rules were applied in the UK it would eliminate most. So both blood systems have to suck it up (sic) and accept blood that other high-quality systems would not. -- Finlay McWalter ☻ Talk 21:03, 8 May 2011 (UTC)

What other bodily components of mine would I be allowed to give for $?

Having been in Germany as a toddler, I can't donate blood. Is there any other part of my body that I CAN donate for cash though? (If not, then please cite a source.) --70.179.169.115 (talk) 07:47, 8 May 2011 (UTC)

Coming from a place where no money changes hands for such activities, I struggle with the concept of getting paid for a donation. (Maybe I should take this to the Language desk ;-) ) HiLo48 (talk) 07:58, 8 May 2011 (UTC)

According to this article, sperm (standards are very high; they don't just take anybody), ova, hair (but you won't make much), and breast milk. Clarityfiend (talk) 08:19, 8 May 2011 (UTC)

Thanks, Clarity. Sorry about the ova and breastmilk. Now the problem is, would anyone please find me the closest sperm bank to Manhattan, KS? Google is, evidently, too squeamish to lend me a straight answer. By the way, how much are you talking, when it comes to donating hair, and where's the nearest hairbank? --70.179.169.115 (talk) 08:49, 8 May 2011 (UTC)

Re: your last question, did you look at the ref or think it was just provided for fun? Nil Einne (talk) 11:00, 8 May 2011 (UTC)

[15] This site seems to have you covered. Looks like if your family's genetic history is good enough, you could be making a small, but non-trivial amount of money by making a commitment to show up and donate 4 to 8 times a month for six months. It also looks like they don't pay out until the six months is over. APL (talk) 07:56, 9 May 2011 (UTC)

Donated hair must normally be pretty long. And how would they know that you were in Germany as toddler? Quest09 (talk) 12:53, 8 May 2011 (UTC)

Because they ask you. Lying about such things in order to get paid for blood would be a very serious thing. --Tango (talk) 15:23, 8 May 2011 (UTC)

• Pardon my ignorance, but why would someone who wants to donate blood not be allowed to do so if they've been to Germany as a kid? Germans seem to have no problem with it themselves and I can't think of any major disasters that would spark such a response. - Mgm|^(talk) 19:35, 8 May 2011 (UTC)
  • See Tort reform. I make no further comment. Tevildo (talk) 19:39, 8 May 2011 (UTC)
  • See the immediately preceding question. The US, Canada, Australia and some others prohibit blood donors from European countries that had apparent outbreaks of vCJD (better known as Mad Cow disease). It is a fatal blood-transmissible prion disease with an incubation period that can be 20-30 years, and at present there is no effective way screen potential blood donors for exposure. Dragons flight (talk) 20:48, 8 May 2011 (UTC)
  • [16] [17] suggest in the US you are ineligible if you lived in Germany (or some other European countries) for a cumulative time of over 5 years unless it was on a US military base. I'm guessing from his previous questions and comments the OP's time in Germany wasn't associated with a US military base therefore the suggestion it was just time spent as a toddler preventing them donating blood seems a little misleading. It's possible commercial blood donation services have stricter requirements (which the OP implied) and similarly there may be stricter requirements if you are trying to donate specific components only (which the OP didn't mention in this question). Also the criteria do change so it's possible the OP is thinking of older criteria. In any case the reason is of course vCJD. Nil Einne (talk) 20:52, 8 May 2011 (UTC)

What kind of insect is this?

Unknown insect

What kind of insect could this be? It was found in South Germany, at an altitude of about 1300 meters. Thanks. --Edcolins (talk) 09:18, 8 May 2011 (UTC)

Probably from the Carabus genus, maybe Carabus auratus. Icek (talk) 09:41, 8 May 2011 (UTC)

Great, thanks a lot. --Edcolins (talk) 10:07, 8 May 2011 (UTC)

FYI: The German Project has a site dedicated to identifying animals and plants. [18] --79.219.83.160 (talk) 11:20, 8 May 2011 (UTC)

Bicycles (and other things) remaining upright

Hi. I've been trying to find out about the age-old question of why a moving bicycle stays upright with apparently almost no effort, and does not immediately tip over like a stationary bicycle does. According to random websites I've visited, the gyroscopic effect of the wheels is not very significant, and the explanation is mainly to do with a combination of deliberate and automatic steering, such that the bicycle adjusts and recovers as it begins to tip. However, and although I have nothing suitable to experiment with at the moment, I can sort of visualise that a small two-wheeled toy with no steering mechanism at all would scoot along upright for a few feet if given a push, yet fall over instantly when stationary. Is this right, and what would be the explanation? One thing I can experiment with is a coin. Coins can easily be made to roll along upright for quite some distance, and then they fall over when they reach a certain minimum speed. What is the reason? Is this also due to some kind of "automatic self-steering"? 86.181.204.130 (talk) 11:45, 8 May 2011 (UTC)

Wikipedia has an excellent article, and a lot of supporting external links, at Bicycle and motorcycle dynamics. You will find your answer there. Dolphin (t) 12:14, 8 May 2011 (UTC)

It's a surprisingly difficult question -- in fact the journal Science published a paper about this just last month. (you can find a Wired blog discussion of the paper here). Looie496 (talk) 16:24, 8 May 2011 (UTC)

Already covered in our article BTW and suggesting it (our article) may therefore be wrong. Nil Einne (talk) 19:12, 8 May 2011 (UTC)

Thanks, that's a meaty article. I haven't even begun to read it properly yet, but it looks very comprehensive. However, note that (despite the title) my question is not actually so much about the stability of real ridden bicycles - which I have already read up on a little - but about the stability of rolling coins and of two-wheeled toys that do not have any steering. 86.181.204.130 (talk) 19:29, 8 May 2011 (UTC)

The thing that keeps rolling coins upright is called the gyroscopic effect, which is shockingly a red link. Some of the information is in the article on bycycle dynamics above, and some is in Gyroscope, but the basic principle is that spinning objects resist torques which are perpendicular to their axis of spin. For a standing coin to fall over, there has to be a torque towards the ground (i.e. a force which acts to rotate the coin along an axis through the coin longitudinally). A spinning coin has an axis of rotation through the center, thin part of the coin. This spin tends to "fight" (for lack of a better term) spins along other axes, and so keeps the coin from turning in a way that would make it fall over. --Jayron32 20:45, 8 May 2011 (UTC)

Gyroscopic effect is a red link but Gyroscope#Properties is blue. Dolphin (t) 23:59, 8 May 2011 (UTC)

More: The concept of the gyroscopic effect is dealt with mathematically in Moment of inertia, which is defined as "a measure of an object's resistance to changes to its rotation". In other words, an object spinning along a certain axis will resist any change to that rotation. For a rolling coin to fall down, the axis of rotation must itself move; and the movement of the axis of rotation is goverened by the coin's moment of inertia. --Jayron32 20:56, 8 May 2011 (UTC)

It all makes sense. The bicycle article cited earlier asserts that the rider's actions keep the bike from tipping over. Even a rider on a stationary or near-stationary bike can keep it standing, with some effort. I suspect the same thing is going on with roller blades. If you watch either a bicyclist or a roller blader from straight in front or behind, you'll see that they are constantly shifting their weight to keep the "center of gravity" in a steady position. For bicyclists, this is more pronounced when they are "standing up in the stirrups", as it were. ←Baseball Bugs ^{What's up, Doc?} carrots→ 23:37, 8 May 2011 (UTC)

The "automatic steering" the OP mentions is caused by the Caster angle that is deliberately designed in to such vehicles: obviously it can't apply to an independent unmounted rolling disk such as a coin. Intuitively (he weaselled) I think it would have less effect the smaller the vehicle, but I wouldn't like to try to prove it mathematically. {The poster formerly known as 87.81.230.195} 90.201.110.223 (talk) 14:33, 9 May 2011 (UTC)

Building the Duomo di Milano today.

I'm not sure if this is the right place to ask this, but how much and how long would it take to build an exact replica of the Duomo di Milano today? --190.19.19.156 (talk) 15:22, 8 May 2011 (UTC)

The Frauenkirche Dresden was rebuilt a few years ago at the cost of € 180 million. The duomo is quite a bit bigger, and the masonry may more complex, so it'd probably more expensive to rebuild. Not sure why one would want to do that, anyway. --Wrongfilter (talk) 19:15, 8 May 2011 (UTC)

Finding bin Laden

If it took so long to find bin Laden when he was in Pakistan, how long will it take, now, that he is in the sea? I don't understand why the USA throw him there in the first place, after such a long search you'll better put him in a place that you cannot loose him again. And what about the bounty of several millions for bin Laden - dead or alive -? If I find bin Laden's body, will I be able to claim it? 212.169.190.212 (talk) 21:43, 8 May 2011 (UTC)

His is no longer in the top 10 most wanted by the FBI. So forget about any bounty. Wikiweek (talk) 21:51, 8 May 2011 (UTC)

Much much longer. By this time, the denizens of the deep will have nibbled on him. On the bright(?) side, after a long enough while, chances are the next fish stick you consume will stand a reasonable chance of containing some of his molecules. As for the bounty, the line forms here[19][20]. Clarityfiend (talk) 21:58, 8 May 2011 (UTC)

There are an infinite number of Bin Ladens, but unfortunately for the bounty hunters, the density is rather low, see here:

A generic prediction of inflation is an infinite ergodic universe, which contains Hubble volumes realizing all initial conditions - including an identical copy of you about 10^{10^29} meters away.

Count Iblis (talk) 23:12, 8 May 2011 (UTC)

It is misleading to say the USA threw him in the sea. Burial at sea is a dignified and respectful way of disposing of bodies at sea. Dolphin (t) 00:06, 9 May 2011 (UTC)

^{On the other hand I'm concerned that we have turned the entire ocean into a Homeopathic strength solution of Bin Laden. --Daniel 00:15, 9 May 2011 (UTC)}

Homopathic strength dilution would be much more dilute than that; no molecules of the diluted substance would be left. So, distilled water can be considered to be a homeopathic dilution of anything. Count Iblis (talk) 00:31, 9 May 2011 (UTC)

I wonder if the Navy has actually secretly trained dolphins or sharks or something to wear a communications device and sniff out recent human corpses deep underwater. Whether for sentimental purposes of recovering their own, or to avoid unfortunate diplomatic incidents... Wnt (talk) 06:27, 9 May 2011 (UTC)

I suggest you get yourself a wet suit and a scuba and start looking, you have nothing to lose and a huge amount of fame if you find the body. You could start around the shores of Spain and then move outward. !Venga, hazlo ahora¡ Richard Avery (talk) 07:44, 9 May 2011 (UTC)

You want to claim a bounty on someone who is already known to be dead? That's not how it works. That's not how it works at all. APL (talk) 07:48, 9 May 2011 (UTC)

Does anyone here know what the average depth of the Arabian Sea would be? ←Baseball Bugs ^{What's up, Doc?} carrots→ 11:16, 9 May 2011 (UTC)

Google Earth tells me that there's a narrow continental shelf, which quickly drops off to depths of over 3,000 metres. (Maybe 10,000 feet.) Is that what you wanted to hear? HiLo48 (talk) 11:32, 9 May 2011 (UTC)

That's sufficient. Of course, we don't know just where they dropped the body. But one would think they would have taken it to the deepest part. It's difficult enough finding an ocean liner or an airplane at those kind of depths, never mind a corpse. And that depth would pretty much rule out scuba. ←Baseball Bugs ^{What's up, Doc?} carrots→ 11:48, 9 May 2011 (UTC)

He could try Bugs, he could try ;-)) Richard Avery (talk) 13:18, 9 May 2011 (UTC)

Sure. No harm in trying, right? :) ←Baseball Bugs ^{What's up, Doc?} carrots→ 13:22, 9 May 2011 (UTC)

It does raise the question of how long human remains can "remain" at such depths. Titanic sat at 12,000 feet for 73 years before it was discovered, and no evidence of human remains was found. The Air France plane that went down a couple of years ago was found at a similar depth, and around 50 bodies were located. For sensitivity reasons, there is little detailed information, and it's reasonable to assume that they have significantly decomposed. The point being that if someone wants to find a lone body in 10,000 feet of ocean water, they prpbably have no time to lose. ←Baseball Bugs ^{What's up, Doc?} carrots→ 13:36, 9 May 2011 (UTC)

pain and pressure

Several years ago I had a spinal tap. (They had to do it six times). Each time they gave a little local anesthetic shot before sticking in the big needle. It still hurt. They said "you aren't feeling pain - only pressure." Whatever it was, it hurt. Is there really a difference between pain and pressure like that, or were they just trying to convince me that it didn't hurt? Bubba73 ^{You talkin' to me?} 23:18, 8 May 2011 (UTC)

Maybe there is some clinical difference that I don't know about, but as a speaker of English, I have to say that if something physically hurts, it's painful. The two are synonymous to me. If there is no pain, it does not hurt. To me saying that "you aren't feeling pain, it hurts - that's all" is like saying "water's not falling from the clouds, it's just raining". Falconus^{p t c} 02:42, 9 May 2011 (UTC)

I agree with the above, but I definitely "get" what they were trying to do. Pain is a very subjective experience, so even just being told you aren't supposed to be feeling pain might have a bit of a placebo effect. I've seen people literally cry from pain when they're getting a shot, before the needle has even touched them.. Vespine (talk) 03:22, 9 May 2011 (UTC)

In dental school, we're taught that there are different sensations and that patients might feel a burning or pricking sensation (for which I will inject more local anesthetic) or a pressure-like sensation (for which we will continue, let's say, extracting a tooth) without administering more anesthetic. I'm no neurophysiologist, but there are many, many types of afferent fibers with many types of nerve tips and maybe anesthesia, if not profound enough, affects some more than others. DRosenbach ^{(Talk | Contribs)} 03:36, 9 May 2011 (UTC)

May 9

R constant

what is the difference between the R in chemistry and R in the physics where in chemistry its value is 8.023 and in physics its value is 2? —Preceding unsigned comment added by Awadheshian (talk • contribs) 10:31, 9 May 2011 (UTC)

How is R used in physics, R commonly represents Rydberg's constant. Plasmic Physics (talk) 11:04, 9 May 2011 (UTC)

First off, units are important! Unless you are talking about a dimensionless constant, you must give units so people know what your numbers mean, or grave consequences may result. I presume that the Chemistry term you are looking for is the gas constant for an ideal gas, although your number does not quite correspond to any of the values at that page. In physics, there is no commonly used physics constant for which a capital "R" is used (the above-mentioned Rydberg constant is used in spectroscopy and quantum mechanics, and its value is not even close to "2" in any system of measurement), but "R" is commonly used to denote the radius of an object in a given problem.-RunningOnBrains^(talk) 11:41, 9 May 2011 (UTC)

The R in physics is likely the ideal gas constant $R=1.98cal/molK$, and the R in chemistry might also be the ideal gas constant $R=8.314J/molK$. Dauto (talk) 13:37, 9 May 2011 (UTC)

It's the same R all around. R is basically the Boltzmann constant extrapolated for a mole of particles, rather than a single particle. That is, it expresses the energy content of a mole of particles represented by a degree of temperature, depending on what your units are. You could easily express R in units of ergs per Rankine per mole if you wanted. The three most common sets of units for R are:

• 8.314 ^J/_mol•K (or .008314 ^kJ/_mol•K)
• 1.98 ^cal/_mol•K (or .00198 ^kcal/_mol•K)
• .0821 ^L•atm/_mol•K

The last one is a bit weird, since it uses a highly "non-standard" energy unit, that being the "liter atmosphere" (L•atm), however that form is highly convenient when working with the Ideal gas law, and some basic dimensional analysis will prove that the L•atm is, in fact, a unit of energy (sorta like some of the other weird energy units like the electron volt). The article gas constant lists a whole mess of possible expressions of R, based on a whole range of energy and temperature units. The use of different values is based on the choice of units to solve the particular problem, which is mainly based on the application of R and the conventions of that application. --Jayron32 14:26, 9 May 2011 (UTC)

Immunology: Neutralization technique

I'm doing some studying for an exam and I'm a bit confused about the purpose of the "nuetralization technique". My understanding is that this technique is used in an effort to figure out which antibodies are present in a sick patient's serum, thus identifying the disease-causing antigen. According to my lecture notes, a test animal is injected with a known antigen (the one potentialy making the patient sick) and antibodies from the patient; if the animal turns out fine, the test indicates that the patient is harboring the antigen in question due to the nuetralizing effect of their antibodies. If the animal ends up sick, the test indicates that the patient is infected with a different antigen. MY QUESTION: The patient is obviously sick, so wouldn't the known antigen make the animal sick regardless if the patient had antibodies against it? Thanks.161.165.196.84 (talk) 11:14, 9 May 2011 (UTC)

Colour of plants.

If black colour is the best for absorbing light, why aren't all photosynthesising plants black instead of green. Seems like an easy adaptation to evolve. Or am I missing something? 110.174.117.185 (talk) 13:17, 9 May 2011 (UTC)

See Chlorophyll#Why_green_and_not_black. Basically, evolutionary history places serious constraints on the options for biochemical machinery. SemanticMantis (talk) 13:40, 9 May 2011 (UTC)

Many organisms capable of photosynthesis do use a combination of different accessory pigments, which allow light of different colors to be absorbed and converted into energy to drive photosynthesis. Phycobilins, for example, are pigments seen in cyanobacteria and red algae that absorb yellow and green light.

There are tradeoffs inherent in expressing multiple pigments, however. Energy that is used to make accessory pigments is energy that can't be used to make chlorophyll a or to grow the plant, and there is a limit to how much protein you can cram into a leaf—more accessory pigments means less absorption of blue and red light per unit area, or a need for larger, thicker leaves. From an evolutionary standpoint, accessory pigments can be challenging to create because they have to not just absorb light, but also efficiently transfer that energy to downstream molecules involved in photosynthesis. In other words, green plant leaves are most likely one of the many examples of evolutionary dead ends reached because they're 'good enough', rather than the 'best'. TenOfAllTrades(talk) 13:43, 9 May 2011 (UTC)

So, unless I'm reading this incorrectly, there is no clear cut answer why. Its one of open questions of evolutionary biology? I mean, all of the explanations are plausible but unsupported either by evidence or very clear cut reasoning.

Has there been any attempts to genetically engineer plants with black chlorophyll? Is there any estimate on how much efficiency plants lose on by not being black? 110.174.117.185 (talk) 14:03, 9 May 2011 (UTC)

I was wondering that also. Ask yourself this, though: Could the world turning black in the spring possibly ever measure up to the world turning green as it does now? ←Baseball Bugs ^{What's up, Doc?} carrots→ 14:05, 9 May 2011 (UTC)

Yes, if that plant was able to feed more people than it's green cousin. Don't get me wrong, I like aesthetics as much as the next guy, but some things take precedent. 110.174.117.185 (talk) 14:14, 9 May 2011 (UTC)

Very poetic, but doesn't really advance the discussion. TenOfAllTrades(talk) 14:18, 9 May 2011 (UTC)

If we had evolved in a world of black vegetation, we would probably find black as pleasant as we actually find green. {The poster formerly known as 87.81.230.195} 90.201.110.223 (talk) 14:21, 9 May 2011 (UTC)

Aren't there some species of plants that are in fact pretty much black? Or am I thinking strictly of flower petals? ←Baseball Bugs ^{What's up, Doc?} carrots→ 15:10, 9 May 2011 (UTC)

The kelp used in sushi, such as Kombu, look black to me. Or are they just a very deep shade of green? ←Baseball Bugs ^{What's up, Doc?} carrots→ 15:14, 9 May 2011 (UTC)

One potentially clear cut reason is the hypothesis that chlorophyll only evolved once. I personally find TOAT's answer above very enlightening, because it points out that more pigments does not necessarily imply more plant productivity. Even if it does happen to be true that 'green plants are less efficient than a hypothetical black plant', this doesn't really say much about the prospects for such a black plant under selective pressure. Lastly, you may be interested in the endosymbiotic theory of chloroplasts, which is currently a well-regarded theory that also explains why chloroplast structure is fairly stable. SemanticMantis (talk) 15:06, 9 May 2011 (UTC)

But how can chlorophyll just "stop evolving"? Every living organism is constantly evolving (on grand scale, not any directly observable by humans), or am I wrong? Even if chlorophyll are a symbiont within the cell, an odd mutation of a black chlorophyll should have spread like wildfire. 110.174.117.185 (talk) 16:20, 9 May 2011 (UTC)

black holes sizes

if a very small black hole "evaporates" quickly even when in close proximity to other matter, and a very large black hole either evaporates very slowly or more importantly is able to grow faster than it can evaporate, then what is the size of the black hole that any BHs smaller than that will evaporate in the presence of other matter, and any HBs larger than that will pull the matter in and grow bigger? —Preceding unsigned comment added by 165.212.189.187 (talk) 14:52, 9 May 2011 (UTC)

This depends on the density of the ambient matter (and also on the avetrage velocity of the surrounding matter paticles). If you have a black hole in vacuum devoid of matter, then it will absorb the electromagnetic background radiation, the neutrino background radiation, dark matter, and the gravitational background radiation. The density of all these components is well known. The rate at which the black hole each of these components is:

1/4 n <v> 4 pi R^2 = n <v> pi R^2

Here <v> is the average velocity of the component (e.g. for electromagnetic and gravitational waves), and R is the Schwarzschild radius. Then you equate this to the evaporation rate of the black hole. To compute that, you determine the Hawking temperature of the black hole, and then you compute the emission rate of photons and gravitons using the usual Stephan-Boltzmann law. I think equilibrium will be reached at temperatures that are a lot lower than the rest mass of neutrinos, so you don't have to add the emission rate of neutrinos here (note that the formula for this emission rate is not the same as for photons, because neutrinos are described by the Fermi-Dirac distribution). Count Iblis (talk) 15:45, 9 May 2011 (UTC)

how electric shock causes death?

how electric shock causes death? —Preceding unsigned comment added by 59.179.150.144 (talk) 16:02, 9 May 2011 (UTC)

The first thing that came to mind was Electric chair, and it has some insights. Basically a strong electrical charge can cause the heart to stop. ←Baseball Bugs ^{What's up, Doc?} carrots→ 16:10, 9 May 2011 (UTC)

One common way, if not the most common way, is by passing through the heart, causing ventricular fibrillation. See Electric shock#Ventricular fibrillation and Electric shock#Lethality. Red Act (talk) 16:13, 9 May 2011 (UTC)

Electric shock can cause the heart to stop, effectively causing death by cardiac arrest. But it can also cause death by medical shock, which despite the identical name has nothing to do with electricity; it instead refers to grave injuries which hamper the ability of the body to move blood around efficiently. Even if the heart is undamaged by the electricity, extensive injuries, such as really bad burns from the electricity, could cause the body to go into medical shock and cause death that way. --Jayron32 16:14, 9 May 2011 (UTC)