Wikipedia:Reference desk/Archives/Science/2011 May 5

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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)