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May 21

Oxidation state trend

Why is it that the vertical trend of stable oxidation states varies so much horizontally across the periodic table? Why is that carbon(IV) is more stable than lead(IV), but osmium(VI) is more stable than iron(VI)? Is there an underlying trend, or is it completely unpredictable? Plasmic Physics (talk) 00:50, 21 May 2012 (UTC)[reply]

These particular cases are due to relativistic effects. Normally, oxidation states increase going down a group because of the progressively looser hold by the atoms on their valence electrons. However, relativistic effects may counter-act that in the cases of Tl, Pb, Bi, and 7th-period elements. They reduce the effect of lower effective nuclear charge by stabilizing particular electron configurations more than in lighter members of the same group.--Jasper Deng (talk) 01:10, 21 May 2012 (UTC)[reply]

I would expect that the stability for high oxidation states should increase down the periods for every group. What is so special about the electron configurations for those cases? Plasmic Physics (talk) 02:28, 21 May 2012 (UTC)[reply]

It seems that the s orbitals for Tl, Pb, Bi are mostly inert, and removing their electrons has less of a stabilizing effect. I don't understand the core reason - since I don't understand relativistic effects. But what is clear is that as the electrons are further and further from the nucleus, the nucleus cares less and less about a full octet than about keeping all those electrons, it appears.--Jasper Deng (talk) 02:53, 21 May 2012 (UTC)[reply]

Could obesity be caused by a lack of magnesium in the diet?

Let me explain why I think magnesium could be a factor in obesity. First, the obvious explanation, i.e. too much calorie intake is, I think, not so plausible, because obese people actually don't eat that much calorie-wise, at least not the obese people who I know. Also, most people will be at some constant weight, so they are in dynamical equilibrium between calorie intake and calorie use. Then that dynamical equilibrium could in theory be reached at any weight, there is no good reason why at an intake of say, 3000 Kcal/day you have to weigh 100 kg, and not 70 kg or 150 kg. Most of the calories are burned by muscles, the fat tissue doesn't use a lot of energy, so you could just as well be at the same equilibrium of 3000 Kcal energy intake and energy use, but at a much lower body weight.

In fact, I weigh only 60 kg, yet I eat on average 3600 Kcal per day. Some of my obese family members eat way less than I do, but they are also eating a lot less healthy foods. Now, some time ago I posted here about magnesium, when I checked my diet I found that my magnesium intake was way too high (I get about 1 gram of magnesium per day from eating whole grain bread, potatoes, brown rice, whole grain pasta, and bananas). However, since then I've read that my magnesium intake may be normal, and that most people are actually magnesium deficient. Now, magnesium plays an important role in metabolism, so I thought that perhaps one can explain why some people are obese as follows.

If I eat X calories a day then I could gain or lose weight until I reach dynamical equilibrium where I burn X calories per day. If my food does not contain enough magnesium, then the metabolism becomes less efficient, it would take a cell longer to burn energy, so for my body to burn X calories per day would take a larger store of energy in my body, therefore I would be a lot fatter. Count Iblis (talk) 03:10, 21 May 2012 (UTC)[reply]

It's always possible, but magnesium is a rather basic nutrient, and if a deficiency caused obesity, I rather think they'd have noticed it by now. I suspect it's a different aspect of their unhealthy diets that are to blame. Also note that it's not always easy to tell how much someone eats by casual observation. I knew an obese woman who seemed to eat modestly at each meal. However, if I went back later for, say, a 2nd piece of pie as a snack, I'd discover that the entire pie had somehow disappeared. :-) StuRat (talk) 03:19, 21 May 2012 (UTC)[reply]

A confounding factor: Most obese people I know may not eat that much more, but what they do that's different, is do a lot less physical work. For example, for quite a while I worked in a company that occupied two floors of a building, and the way the company laid out their operations, and the type of work done, meant that most empoyees had to frequently walk from one floor to the other. Most of us took the stairs as that was quicker. But, with no exceptions, obese folks used the lift every time. Also you could use free public carparks about 6 block away, or you could park in the basement at $20 per day. Guess which folks paid the $20/day for their own cars! We ran construction projects. I've never seen an obese labouror, and seldom seen a fat one. Ratbone120.145.172.175 (talk) 03:44, 21 May 2012 (UTC)[reply]

You don't live in the UK do you! I've seen plenty of obese brickies here in my time... --TammyMoet (talk) 09:50, 21 May 2012 (UTC)[reply]

No, I live in Australia. Brickies are paid per number of bricks laid and use labourors/assistants to keep them constantly supplied with bricks and fresh mortar. So the faster they go, the more money they make. Are they paid by the hour, or at a flat rate, in the UK? Bricklaying is damm hard work. Ratbone60.230.230.72 (talk) 10:57, 21 May 2012 (UTC)[reply]

It is more complicated than that. As Tammy says, manual labourers can still be obese. I know women who have struggled with their weight their whole lives, and are definitely well into the obese range by any metric (not just BMI), but who regularly take the stairs, dance for hours at proper dance classes, walk miles most days (one is building up to a huge walking holiday), and so on. They wear pedometers everywhere, every day, so that they can make sure they keep up their distance. When their doctor gives them the same patronising advice they give everyone, the doctor flatly disbelieves that they do this exercise. This will change, as I have seen the data from recent studies starting to be properly propagated. Exercise makes you hungry. And if you've been struggling with your weight all your life, dieting from a young age, then your body gets really efficient at laying down fat and holding onto it. 86.161.213.137 (talk) 11:02, 22 May 2012 (UTC)[reply]

Is it even possible to avoid ingesting magnesium to the extent that one becomes deficient? Roger (talk) 09:55, 21 May 2012 (UTC)[reply]

Yes, actually. 57% of the US populace has inadequate magnesium intake according to the USDA. Also, certain medications affect magnesium absorption: transplant patients are often put on supplements because ciclosporin (an important anti-rejection drug) impedes magnesium absorption. --NellieBlyMobile (talk) 22:41, 21 May 2012 (UTC)[reply]

There are many things written about this, but see [1] for a good publication pointing at obesity-induced type II diabetes as the cause of lowered magnesium levels, rather than the other way around. Wnt (talk) 02:10, 23 May 2012 (UTC)[reply]

Cartography - resolution?

Is there a concept in cartography that is analogous to resolution? By this I mean, will a particular map have a property that, say, features smaller that 10m2 are ignored? I just want to know what this is called so that I can read about it. ike9898 (talk) 14:04, 21 May 2012 (UTC)[reply]

You may find the Coastline paradox article interesting. hydnjo (talk) 14:22, 21 May 2012 (UTC)[reply]

I think, as a practical matter, a map will have a higher resolution in areas which are "interesting". Thus, a street map of the US will show more detail in cities than, say, the Alaskan interior. This would apply to street maps, while maps for geologists might have more detail in areas with interesting geology. The increased detail is sometimes handled with an inset map at increased scale, but not always. On a Google map, for example, you may find that you can't zoom in as far in uninteresting areas, or, if you can, you don't see any additional detail when you do. StuRat (talk) 06:07, 22 May 2012 (UTC)[reply]

There might not be a standard name for the concept, but Googling 'mapping detail threshold' gets a relevant result. In Mapnik (the standard renderer used by OSM) they call it 'detail level'. --Heron (talk) 20:23, 22 May 2012 (UTC)[reply]

steam engine plans

I want to make a working 1/12 scale model of this: http://upload.wikimedia.org/wikipedia/commons/f/f3/TrevithicksEngine.jpg or something much like it, any ideas where I can find plans of how it's made?

Kitutal (talk) 16:12, 21 May 2012 (UTC)[reply]

10 seconds of google revealed this thread http://www.model-engineer.co.uk/forums/postings.asp?th=47132 which might be of use. There are also companies that sell live steam models. --TrogWoolley (talk) 16:27, 21 May 2012 (UTC)[reply]

If this is to be a working model, make sure that you realize that, if the thickness of the steam tank is 1/12th the original, then the pressure differential with the atmosphere must be much less, as well (I'm not sure if it's 1/12th, though). You don't want an exploding tank. However, if the volume is 1/12³ or 1/1728, and the pressure differential is 1/12, this will do something like 1/20736 times as much work. This might not even be enough to make it move (specifically, to overcome the static coefficient of friction and rolling resistance). So, you might want to keep the tank thickness the same as the original, rather than scale it down, so it can handle higher pressures. StuRat (talk) 06:00, 22 May 2012 (UTC)[reply]

While safety of course are very important when building a steam engine theoretical the maximum pressure is the same for an exact scale model. This can be seen by looking on any cut trough the boiler. The force are the inside area multiplied by pressure and the needed material strength are proportional to the force divided by the cross section area of the boiler wall. The areas will scale by the same factor so the maximum pressure will be the same. Gr8xoz (talk) 08:15, 23 May 2012 (UTC)[reply]

Sorry, but that doesn't make any sense. The pressure must be reduced in a tank with reduced thickness, or else all tanks would be made of a thin foil. StuRat (talk) 17:33, 23 May 2012 (UTC)[reply]

Would you be so kind to actually read what I write and think about it before you try to contradict me. I wrote that if you scale down a big tank so that all proportions are kept the same then it can withstand the same pressure. If you need a big tank you still need thick walls. A hot coke can has about the same pressure as a workshop compressor tank but the coke can is 0.1 mm thick while the compressor tank is several millimetre thick.

Lets take an example tank A has an outer diameter of 2000 mm and an inner diameter of 1900 mm, the wall material has an allowed average tensile stress of 100 N/mm^2 in the axial direction. What is the allowed pressure? The total wall cross section area is 2000^2*pi/4-1900^2*pi/4= 306 000 mm^2 the allowed force are 100 N/mm^2*306 000 mm^2=30.6 MN. The inner cross section area of the tank is 1900^2*pi/4 mm^2 = 2.8 m^2 The allowed pressure is 30.6 MN/2.8 m^2= 10.8 MPa. Very similar calculations needs to be done in the tangential direction.

Lets scale it down by a factor 100, tank B has an outer diameter of 20 mm and an inner diameter of 19 mm, the wall material has an allowed average tensile stress of 100 N/mm^2 in the axial direction. What is the allowed pressure? The total wall cross section area is 20^2*pi/4-19^2*pi/4= 30.6 mm^2 the allowed force are 100 N/mm^2*30.6 mm^2=3060 N. The inner cross section area of the tank is 19^2*pi/4 mm^2 = 0.00028 m^2 The allowed pressure is 3060 MN/0.00028 m^2= 10.8 MPa.

Both tanks can withstand the same pressure even if the wall in the big tank is 50 mm thick and the wall in the small tank is 0.5 mm thick. If you do not agree with this then you need to show some REAL ARGUMENTS. Gr8xoz (talk) 21:58, 23 May 2012 (UTC)[reply]

Just checked with an expert (he volunteers at the Southeastern Railway Museum, working on steam engine locomotives). They are currently building a scale model (half scale, though, not 1/12th scale). He agrees that the thinner the wall thickness, the less pressure the tank can hold, regardless of the size of the tank. StuRat (talk) 01:34, 24 May 2012 (UTC)[reply]

That contradicts what our Pressure tank article says here: "(for a given pressure) the thickness of the walls scales with the radius of the tank" (which agrees with what Gr8xoz wrote). -84user (talk) 18:56, 26 May 2012 (UTC)[reply]

Yea, or just hide a little battery powered motor inside Kitutal (talk) 15:57, 22 May 2012 (UTC)[reply]

Purple lightning

I was watching this video, http://www.youtube.com/watch?v=RDDfkKEa2ls&feature=related

And some of the lightning looks quite purple. What causes that? Is it just the camera, or does it really look purple? ScienceApe (talk) 16:27, 21 May 2012 (UTC)[reply]

If the camera is using a whitebalance for fluorescent lighting, which is greenish, then other real white stuff like lightning can look purplish. Graeme Bartlett (talk) 21:47, 21 May 2012 (UTC)[reply]

Also, lightning, like all other sources (or reflectors) of light, is subject to atmospheric effects. Thus, distant lightning, like distant mountains, will tend to look more purple. StuRat (talk) 05:49, 22 May 2012 (UTC)[reply]

Distant mountains appear more blue, not more purple. If that was the reason for lightning appearing not quite white, the lightning would appear blue, not purple. Whoop whoop pull up ^{Bitching Betty | Averted crashes} 04:44, 24 May 2012 (UTC)[reply]

The author of America the Beautiful disagrees: [2]. StuRat (talk) 05:07, 25 May 2012 (UTC)[reply]

Well, then, that guy is wrong. Whoop whoop pull up ^{Bitching Betty | Averted crashes} 22:10, 25 May 2012 (UTC)[reply]

Distant lightning would only be made more blue if it was daylight with sky colour adding to it. If it was at night time, blue would be removed, making the colour more yellow or even red if it goes through smoke. Graeme Bartlett (talk) 22:37, 25 May 2012 (UTC)[reply]

Comparing climate between places in Australia & North America

Is there somewhere in North America that would have a very similar climate to that of Sydney, Australia for example? Or Perth, Australia?

More generally, are there tables that answer such questions?

Eg, is the climate of Portugal very similar to that of Northern California (both being on the west coast of a continent and at the same latitude)? Thanks, CBHA (talk) 19:43, 21 May 2012 (UTC)[reply]

Well, there's the Köppen climate classification system. Per that map, Portugal and coastal California are both Mediterranean climates (Csa or Csb on the Koppen map). Sydney appears to be in an oceanic climate region, of which there is little in North America (perhaps around Seattle or Vancouver) but loads in Europe. It may also be useful to pull up single-factor maps such as average temperature or rainfall. — Lomn 21:03, 21 May 2012 (UTC)[reply]

I think I see a 2nd area around Knoxville, Tennessee with an oceanic climate, similar to Sydney. As for Perth, it's Mediterranean climate is, indeed, common on the US West coast, including California, Oregon, and Washington (state). StuRat (talk) 05:32, 22 May 2012 (UTC)[reply]

Diversity of sexuality

I've sometimes heard people claim that the diverse sexual tastes of humans is a feature that distinguishes us from all the lower animals. However, I'm heavily skeptical of any claim that separates humans from the natural world and declares "we are unique amongst all species". So, do other animals have unusual sexual interests? Are there chimps, for example, who enjoy sadism, necrophilia, pedophilia, or foot fetishes (assuming these aren't typical amongst the species)? --140.180.5.169 (talk) 19:57, 21 May 2012 (UTC)[reply]

The concept of sexuality is something which, in itself, is a human-created idea. To assign sexuality to an animal is to disrepect it by anthropomorphizing it. Animal behavior is to be understood on its own terms, not by analogy to human behavior. Animals are not incomplete people, and we cannot hope to understand them properly by starting with the premise that they are. Assuming that animal behavior has human analogues, or that the classifications of animal behavior fit in the same schema as we have created for human behavior is a wrong-headed tack. --Jayron32 23:01, 21 May 2012 (UTC)[reply]

(ec) I don't accept the validity of the artificial wall you're putting up between human and animal sexual behavior. While the word "sexuality" was invented by humans, sex itself predates the first multicellular organism and is several orders of magnitude older than all of human history. To say that human sexuality is unique in a profound way, instead of being just a variant of one of the oldest and most widespread biological phenomena, seems very anthropocentric and anti-Copernician. — Preceding unsigned comment added by 140.180.5.169 (talk) 23:31, 21 May 2012 (UTC)[reply]

The problem is, how do you ask questions about animals and their internal thought processes? Where is your evidence that animals experience the sort of metacognition necessary to experience sexuality in the same way that humans do (this as being distinct from sexual behavior or the act of sex). That is, animals have sex, and they have sexual behaviors, but they do not have the same values that are assigned to those behaviors that human culture does. How entirely presumptuous of you that animals should have the same values that humans do, and how disrespectful to those animals to meet them on your own terms, and not on their own terms. How can you consider humanity to be so superior to animals that you can judge what animals do solely on the motivations, values, and culture of human? What a horribly anthropocentric view of the world you have. --Jayron32 00:20, 22 May 2012 (UTC)[reply]

My question was entirely about animal and human behavior, not about internal thought processes or values. It is empirically difficult with current technology to determine whether a chimp believes that a foot fetish is socially acceptable or jibes with his beliefs, but that's not what I'm interested in. I only care about whether chimps have foot fetishes in the first place, precisely because internal thought processes are hard to determine. --140.180.5.169 (talk) 02:16, 22 May 2012 (UTC)[reply]

Bonobos, dolphins, and chimpanzees are known to engage in sexual intercourse even when the female is not in estrus, and to engage in sex acts with same-sex partners. Like humans engaging in sex primarily for pleasure, this behaviour in the above mentioned animals is also presumed to be for pleasure, and a contributing factor to strengthening their social bonds. 84.209.89.214 (talk) 23:23, 21 May 2012 (UTC)[reply]

Veering way off-topic into non-scientific discussion and personal attacks. — The Hand That Feeds You:^Bite 12:47, 23 May 2012 (UTC)[reply]

The following discussion has been closed. Please do not modify it.

I don't think one can properly distinguish the motives for mating in animals. They mate because they feel the urge to, without realizing why. That they get pleasure from it does not mean its purpose is not reproduction. Rather, animals (and humans too) derive pleasure from sex precisely because sex leads to reproduction. Animals having the urge to mate even when there are no fertile opposite-sex partners available takes nothing away from the fact that the urges they feel have the purpose of reproducing. -Lindert (talk) 23:28, 21 May 2012 (UTC)[reply]

Have you ever heard of homosexuality, Lindert? Or are those people not quite the same as humans? -- ♬ Jack of Oz ♬ ^{[your turn]} 06:00, 22 May 2012 (UTC)[reply]

I do make a distinction between humans and animals. Animals don't know why they do something, while humans do. In animals, homosexuality is usually the result of either the unavailability of suitable/willing opposite sex partners, or the inability to distinguish between the sexes. Apart from these reasons however, some humans seem to be sexually attracted exclusively to the same sex. Thus they have a distorted sexuality, and satisfy their urges in a manner not intended by nature. This used to be viewed simply as a psychological disorder, same as e.g. necrophilia, but is now, due to political correctness and the homosexual lobby increasingly considered normal. - Lindert (talk) 07:20, 22 May 2012 (UTC)[reply]

Oh dear. I think we should challenge that view. Since this is the science desk, can you point to mainstream scientific evidence that homosexuality is distorted, abnormal, or a psychological disorder ? Gandalf61 (talk) 08:39, 22 May 2012 (UTC)[reply]

The problem with the word abnormal e.g. is that it is very subjective, and can even imply a value judgement, thus falling outside the realm of science. Homosexuality was removed from the APA's list of mental disorders in 1973, shortly after the emergence of widespread gay activism. This was viewed by many as a political decision, rather that a scientific one. In Mental Health Policy and Practice Today (1997) Watkins and Callicut write: "many laypersons were horrified to see that the decisions about the psychopathology or normality of homosexuality were so blatantly political, determined by a mere vote of psychiatrists. What they apparently did not realize was that both the classification and the diagnosis of all mental disorders are higly political" ([3]). Still, even recent studies link homosexuality to childhood trauma (see e.g. [4]). Several studies have also shown that homosexual behavior reduces life expectancy by over 10 years (more than smoking). Something that often results from trauma (usually sexual abuse) and causes unhealthy behavior is clearly a disorder, it's just politically incorrect to say it out loud. By the way, if science is restricted only to the mainstream, there would be no room for critical thinking, and that's simply deadly for science itself. In summary, calling it a disorder or not is merely a matter of politics, not science. - Lindert (talk) 11:06, 22 May 2012 (UTC)[reply]

Your claim that homosexuality "often results from trauma (usually sexual abuse)" is simply not supported by the study that you cite [5]. That study did find a small correlation between sexual orientation that was not exlusively heterosexual and "adverse events" in childhood - but of the 29 types of adverse events covered by the study, only 2 were sexual in nature; the remainder included events such as a life-threatening illnes, a major natual disaster, death of someone close etc. And out of the 358 study subjects that experienced three or more adverse events in their childhood, over 80% were exclusively heterosexual in their sexual orientation. It would be interesting to see whether you have similarly misinterpreted the other unidentified studies that you mention. Gandalf61 (talk) 12:28, 22 May 2012 (UTC)[reply]

It was only one of many studies that support a similar correlation, this was just the first I could find. Maybe a better example is this study, which finds that 46% of male homosexuals experienced homosexual molestation as a child, as opposed to 7% of heterosexual males, for females the numbers are 22% and 1% respectively. Regardless, whatever the cause, my point remains that its mostly politics that determines what is a disorder. - Lindert (talk) 12:36, 22 May 2012 (UTC)[reply]

And yet, you seem quite relaxed about using that politically-determined label of "disorder" to support your assertion that homosexuals "have a distorted sexuality, and satisfy their urges in a manner not intended by nature". Is it the case that either (a) politics now determines what is or is not "intended by nature", or (b) our views on this subject, or anything at all, should always be subject to the filter of political correctness? Who makes the politics of these things in the first place, and where do their views come from? -- ♬ Jack of Oz ♬ ^{[your turn]} 12:55, 22 May 2012 (UTC)[reply]

Mostly the social views on things like homosexuality come from a particular world view. Of course my opinions on a subject influence how I speak about it. I'm biased as is everyone else. However, I classify it as a disorder primarily for consistency's sake. Because fundamentally, I see no difference between e.g. homosexuality and zoophilia, necrophilia, pedophilia etc., so it would be inconsistent to classify some as disorders and not others. Also, what behaviors are 'intended by nature' are quite self-evident. One does not need to be a doctor to figure out that the anus is not meant for sexual intercourse. For example, the vagina is naturally lubricated, while the anus is not. Homosexual activity results in many STDs, infections and other medical issues. - Lindert (talk) 13:15, 22 May 2012 (UTC)[reply]

Lindert, what on earth do you mean by "intended by nature"? Not just with reference to homosexuality, but anything? Nature has no intention. Egg Centri c 13:31, 22 May 2012 (UTC)[reply]

Also, any idiot can distinguish between homosexuality, zoophilia, necrophilia and pedophilia. Having sex with people of the same sex as you is obviously not the same thing as having sex with a dead body, and having sex with a child is obviously not the same thing as having sex with a sheep. The fact that you use the different names we have for these practices means you recognise these differences. So, in what possible sense is there "no difference" between them? Also, natural childbirth is a process that can take up to 48 hours, involving immense pain to the mother and usually surgical intervention and a number of days recovery in a hospital. I've never heard of anyone who voluntarily engaged in anal intercourse having anything remotely like that experience - they usually report it's intensely pleasurable and want more of it as soon as possible. The fact that external lubricant is required is no more "unnatural" than the painkillers given to women in labour. -- ♬ Jack of Oz ♬ ^{[your turn]} 22:34, 22 May 2012 (UTC)[reply]

You completely missed my point. If you read carefully, you'd have noticed that I said that fundamentally I see no difference, not that they are entirely the same. It is equivalent to saying that fundamentally, black people are no different from white people. Don't just take part of a sentence and ignore the rest. The sense in which they are the same is that all are deviations from the usual practice. All involve negative health effects to the individual(s) engaging in it. In short, to me it seems inconsistent that some are viewed by Western society as abnormal and others as normal.

Also, you're grossly exaggerating natural childbirth, which is very common in most countries and does not usually involve 'immense pain' and rarely surgical intervention or recovery in a hospital. Natural births taking more than a few hours are rare. There's excellent medical care in the Netherlands, where I live, and still 30% of women choose to give birth at home. Only 10% of women here use painkillers during childbirth. - Lindert (talk) 11:55, 23 May 2012 (UTC)[reply]

You do know that correlation does not imply causation, right? Your study could suggest that child abuse leads to homosexuality, but it could equally well suggest that homosexuality leads to child abuse. If you were that child's parent, for example, I can see plenty of reasons why homosexuality would lead to child abuse--because you'd view your child as deviant and be intolerant of him/her.

Even if we assume that child abuse does lead to homosexuality, I don't agree that this means homosexuality is a disorder. It means that we should provide love and understanding to the child for his/her miserable past, which is the opposite of what you'd probably provide. It does not automatically imply that homosexuality is harmful to either the patient or society at large, which is the most basic criterion I'd use for a "disorder". --140.180.5.169 (talk) 20:36, 22 May 2012 (UTC)[reply]

I fully agree. even if there is a causal connection that does not automatically make it a disorder. And you are absolutely right about the most basic criterion. Studies have shown that practicing homosexuals have a reduced life expectancy by about 8-20 years (link) and experience significantly more mental disorders (link). Of course it is well known that STDs are much more prevalent amongst homosexuals, and it is obvious that STDs negatively effect the quality of life. Of course one needs to be careful with correlations, but still, it would seem there is reason enough to view it as a disorder. - Lindert (talk) 21:57, 22 May 2012 (UTC)[reply]

The second study implies nothing about the direction of the causation, because it is easy to see why a marginalized minority would be at greater risk of mental illness, especially substance abuse and depression. In fact, the authors themselves make this point. I believe the first study is accurate, and does suggest that homosexual sex is much riskier, for the reasons you suggested. However, the study is outdated. The authors themselves revisited the issue here: http://ije.oxfordjournals.org/content/30/6/1499.full.pdf+html and found that "In contrast, if we were to repeat this analysis today the life expectancy of gay and bisexual men would be greatly improved. Deaths from HIV infection have declined dramatically in this population since 1996. As we have previously reported there has been a threefold decrease in mortality in Vancouver as well as in other parts of British Columbia."

Note that in my post, I listed only what I considered the most basic criterion, not the full criteria. This is because I'm uninterested in the semantic debate over what counts as a "disorder". I note, however, that you seem to be using a definition that's much too broad. If your only criterion for a disorder is that it negatively affects quality of life, then being a woman, an urban resident, single, or unemployed all count as disorders, because according to the mental disorders study you linked to, "psychiatric epidemiological studies among the general population in industrialized countries on three continents have repeatedly shown increased morbidity" in those populations.

Finally, you seem to be using the wrong metric to measure the cost of homosexual sex. The cost is not the risk relative to heterosexuals, because there is no known way of turning a homosexual into a heterosexual. Rather, the correct opportunity cost is the cost, for a homosexual, of not engaging in sex. This excludes the possibility of many types of personal satisfaction and relationship building. Whether the risk of STDs and decreased lifespan is worth the opportunity cost of a loveless (or at least sexless) life is a value judgement that every person must make for themselves. I personally think the risk is worth it, just as I think the convenience and opportunities of living in a city outweigh the costs of increased air pollution, more carcinogens, overcrowding, increased crime, etc. The guy down the street might completely disagree, and there's no problem with that. --140.180.5.169 (talk) 03:50, 23 May 2012 (UTC)[reply]

Being a woman, urban resident, single or unemployed are different categories that do not fulfill the APA's criterion of being a "behavioral or psychological syndrome or pattern that occurs in an individual", while homosexual activity can surely be described as a behavioral pattern. It's likely true that life expectancy has increased due to advances in medical treatment. I never brought up the issue of opportunity cost (though you do have a point there), I merely pointed out there are negative health effects, which you apparently agree with. - Lindert (talk) 07:00, 23 May 2012 (UTC)[reply]

I mean just the obvious with 'intended by nature'. For example, one could ask the question "Why do some snakes have venomous teeth?". I would answer: "In order to kill their prey". If I take your approach I would have to say: "There is no answer, nature has no purpose, it just is". - Lindert (talk) 13:41, 22 May 2012 (UTC)[reply]

That's a ridiculous view. Why doesn't nature give the snake sub machine guns instead? Egg Centri c 14:00, 22 May 2012 (UTC)[reply]

Agreed. In mainstream science, nature indeed has no purpose, and teleological explanations are avoided. I think we may be heading into the realms of intelligent design here. Gandalf61 (talk) 14:13, 22 May 2012 (UTC)[reply]

Teleological explanations are not avoided, because they cannot be avoided. One cannot study biology without studying the function (= purpose) of biological structures. As an example, see this article in Science magazine about the function of the narwhal's tusk. It states researchers have long been fascinated with this mysterious structure, precisely because it was unknown what purpose it served. - Lindert (talk) 14:28, 22 May 2012 (UTC)[reply]

There's lots of reasons. For instance, ammunition would be hard to come by. To obtain enough metal, snakes would have to dig mines, which is hard without arms. - Lindert (talk) 14:29, 22 May 2012 (UTC)[reply]

"Function" is definitely not the same as "purpose" ! "Function" addresses the question "what does this do ?", which is a legitimate scientific question. "Purpose" addresses the question "why does this exist ?", which is not a legitimate scientific questions, because "purpose" assumes a guiding intelligence. Lindert, your ideas are very strange, and some of the views you have stated above are really quite offensive. Gandalf61 (talk) 14:45, 22 May 2012 (UTC)[reply]

I don't really care if my views are 'strange', and of course you have the right to be offended, but luckily, Wikipedia is not yet censored. In a teleological sense, the question "why does this exist?" is really equivalent to "what does this do?". The terms 'function' and 'purpose' are often used interchangeably, also in biology. For example, this article, titled Long noncoding RNAs: the search for function starts of by saying that researchers found "a steady stream of transcribed regions with no apparent purpose.". In this context, purpose and function are simply synonyms. - Lindert (talk) 15:03, 22 May 2012 (UTC)[reply]

Agreed that Wikipedia is not censored, however most editors here choose to stay within the grounds of common decency and politeness, and do not go out of their way to cause gratuitous offence. You are clearly an unfortunate exception who wishes to use Wikipedia as a soapbox to promote your extreme, illogical and out-dated opinions. I am done here. Gandalf61 (talk) 15:25, 22 May 2012 (UTC)[reply]

I don't see how I have been impolite. I have said nothing at all about any editor, but merely expressed my personal opinions and arguments. If that's being indecent then so be it. I have not called anyones views 'extreme, illogical and out-dated' (no offense taken tough). - Lindert (talk) 15:34, 22 May 2012 (UTC)[reply]

You are saying that homosexuality is deviant because humans are not using their body parts for what they are intended for. This position only makes sense at all if you do believe them to have a higher, specified purpose. Otherwise you might as well argue using glasses is deviant because ears aren't to rest specs on, driving is deviant because feet aren't meant to operate brake pedals, etc etc. Egg Centri c 15:53, 22 May 2012 (UTC)[reply]

First of all, I do believe there is a higher purpose in nature (but please let's not start a discussion on that). Secondly, I don't think the examples you give are really parallel. Besides body parts, we also have a brain for a reason. One of the functions of the brain is to devise and make use of tools. We are indeed by nature dependent on tools. Without tools (and clothes), no human population on earth would be able to survive very long. In contrast, as I mentioned above, homosexual behavior is generally detrimental to peoples health. A closer parallel would be for example listening to very loud music. Doing this is detrimental to ones hearing, because human ears are not able to withstand such sound levels for prolonged periods. Thus, it could be said that this is a 'deviant' or 'unnatural' use of the ears, because ears are not designed/suited for this. - Lindert (talk) 18:37, 22 May 2012 (UTC)[reply]

If you do believe there's a higher purpose in nature, and you base your opinions on that, your views are not scientific and have no place on the science desk. Since they're obviously hateful and intolerant, I would even say they have no place in the human world, but let's not get into that. If you really believe nature has any purpose, you are either a superstitious crackpot or ignorant about how evolution works. One of the basic aspects of evolution that all high school biology students know (or at least should know) is that it has absolutely no purpose. It is not true that a cat's children will be more human-like than the parent, or even that they'll be better cats. Mutation is a random process, and even though positive mutations are more often kept, the E. coli long-term evolution experiment show that neutral mutations often have a large impact on the population's genetic future. Even detrimental mutations are sometimes kept if a physical barrier causes a founder effect and makes the mutation dominant within the population. If you believe that it's purposeful for a UV photon to hit a piece of DNA at precisely the right angle to cause a certain mutation, be my guest, but that's a crackpot view which few others would accept. --140.180.5.169 (talk) 20:36, 22 May 2012 (UTC)[reply]

if you don't believe in a higher purpose, how can you decide whether veiws have a place in the human world?

Do you believe you are using a mouth incorrectly if you eat so much it makes you fat? What about if you use it to spout bigotry? Sorry to tell you this, but if there is any purpose in nature, it's obvious to the rest of us that you've got it soooo wrong with whatever silly, presumably abrahamic god-type thing you believe. Prick. Egg Centri c 21:10, 22 May 2012 (UTC)[reply]

Please read Wikipedia's policy of no personal attacks. It's fine to disagree, even passionately, just don't make it personal please. thank you - Lindert (talk) 22:07, 22 May 2012 (UTC)[reply]

"homosexual behavior is generally detrimental to peoples health" Say what now? Also, one of the functions of genitalia is to provide sexual gratification. Homosexual sex is not deviant even by your definition. thx1138 (talk) 22:18, 22 May 2012 (UTC)[reply]

lets put it this way. evolution should in the long run cause homosexuality to die out. therefore from an evelutionary perspective it is deviant from the norm of the species.

"Say what now?" So can you tell me in what way that comment was a personal attack or hateful? If I had said "smoking is generally detrimental to peoples health", would that be hateful? It is simply a statement of fact, that is backed up btw by numerous scientific studies. And yes, sexual gratification is a function of the genitalia; so does that mean necrophilia is not deviant? - Lindert (talk) 22:26, 22 May 2012 (UTC)[reply]

I didn't accuse you of being hateful or making a personal attack. I'm accusing you of making a false statement, with no supporting citation. Unlike smoking, homosexual behavior is not generally detrimental to people's health.thx1138 (talk) 22:30, 22 May 2012 (UTC)[reply]

I apologize, I misunderstood you. I provided references for my claim in the comment above in response to 140.180.5.169. I'll quote it here: "Studies have shown that practicing homosexuals have a reduced life expectancy by about 8-20 years (link) and experience significantly more mental disorders (link)". If you like, I could cite similar studies to the same effect. - Lindert (talk) 22:57, 22 May 2012 (UTC)[reply]

That study does not support your statement. Also, it is only of gay men, not women. thx1138 (talk) 23:16, 22 May 2012 (UTC)[reply]

You are right that the study only considers gay men. There is much more data available on men, as social and medical research more often investigates men. The studies do however show a correlation between life expectancy, mental disorders and homosexuality. If that is not clear enough, what about this one. This study finds that homosexual men have about 60% higher cancer rates compared to the general population. - Lindert (talk) 23:25, 22 May 2012 (UTC)[reply]

Screw you, deviant. You deserve to be personally attacked. People are too tolerant of opinoins like that. You are personally attacking some of the contributors to this thread (not including me incidentally), and also offending all right thinking people (probably not including me either) and everyone else who hates bigotry (woohoo, I get to join in). You are pushing pseudoscience to the detriment of all mankind. If I'm doing anything wrong by saying so then eventually wikipedia needs to change the rules. Do you think that someone here who kept advocating slavery as natural and what nature intended would stay on the reference desk 5 minutes? There's much more evidence (in a sense that 0 > 0) for slavery being nature's intention than there is for pure heterosexuality. Egg Centri c 22:47, 22 May 2012 (UTC)[reply]

Cool it, Egg Centric. People are actually permitted to have opinions that are different from yours. There's no justification for that personal attack; our rules prohibit personal attacks, no matter what the (perceived) provocation may be. -- ♬ Jack of Oz ♬ ^{[your turn]} 23:28, 22 May 2012 (UTC)[reply]

Yes, but they don't have complex language with a distinction between signified, signifier and referent. Chimpanzees enjoy injuring other chimpanzees, they don't experience sadism. Animals copulate with animals that lack reproductive maturity. Animals don't have "children" as a unique category of social being, and so are incapable of "pedophilia" as sex with a child. Animals do not have sexuality, they have sex and sexual behaviours. Animals lack culture, because they lack language. Animals lack sexual taste, because they lack language. Fifelfoo (talk) 23:33, 21 May 2012 (UTC)[reply]

I don't understand your distinction. If the same neural mechanism in both chimps and humans cause the organism to enjoy hurting others, why do you call one sadism but not the other? If certain neurons fire to arouse a human when he sees a young child, and the same neurons fire to arouse a chimp when he sees a young chimp child, why is one pedophilia but not the other? I also question your claim that animals don't have "children" as a unique category. Animals certainly behave differently towards children than they do towards adults, and many social species have a rigid social structure where children have a well-defined place. --140.180.5.169 (talk) 02:16, 22 May 2012 (UTC)[reply]

Dogs hump legs HiLo48 (talk) 23:34, 21 May 2012 (UTC)[reply]

Animals are, well, animals. For example: this chimp with a toad fetish. Also, here is an example of chimp fellatio. Of course, people are sexual animals too... :-) Agentundertables (talk) 00:06, 22 May 2012 (UTC)[reply]

Based on some of the above responses, it seems to me that the editor who asked this question stepped into a minefield of something comparable to "political correctness" (or incorrectness) because of the way they worded the question.

If the question is reworded in a more "neutral" way, what are the answers? My attempt at rewording follows.

Do non-human species engage in the following sorts of activities? And if so, is there evidence that sexual arousal is occasioned by these activities?

-- Hurting/torturing other animals for no apparent good reason

-- sexual "intercourse" with dead animals, i.e., penetration of dead bodies with a penis?

-- sexual "intercourse" with immature members of the same species?

-- sexual "intercourse" with animals of another species?

Kind of a tacky subject but I understand that Wikipedia is not censored. (Just for the record, I am not asking here for medical or legal advice. :o) Thanks, CBHA (talk) 02:43, 22 May 2012 (UTC)[reply]

Dolphins will maim and kill other animals for no apparent porpoise. Animals that were not threatening, and that the dolphins have no intention of eating. Is there a purpose to it? You could argue that they are "practicing", I suppose, or fulfilling an evolutionary urge, but nobody knows. Certain species of frog will have intercourse with very obviously dead (re: squashed, rotting) frogs. But once again, is that for fun, or is it fulfilling an urge, or what? I can't think of any animals that have sex with juveniles. As for interspecies sex, that definitely happens a lot. Take a mule, for instance. If the animals are closely related enough, you don't even need to coax the two to get it on. And I'm reminding of that hilarious picture of a dog getting it on with a duck. But like everyone else is saying, who knows why these animals are acting this way. In some cases we can definitely tie a weird sexual behavior to biology. There is a mutant strain of mice in which all the males are bisexual, and we know that's because in that strain, males cannot smell the difference between a male and a female. But in most cases we really have no clue. It's possible the animal just likes it that way, but anyone who tells you that is guessing. Someguy1221 (talk) 05:01, 22 May 2012 (UTC)[reply]

My ex has nice feet, and I'm thinking that foot fetishes are possibly more of a unique behavior, or are manifested more strongly, with us humans, on account of our much greater dependency on needing superb feet for upright walking. Although the OP did ask about a minefield of human taboos, they also asked a much more general question regarding "unusual sexual interests" and most large primates and odd birds don't seem need to ever need to shop for attractive shoes though. Agentundertables (talk) 03:33, 22 May 2012 (UTC)[reply]

Wow, could you guys pontificate about your woodshop notions of anthroprocentrism a little bit more? We're all animals. There are plenty of animals with non-procreative sexual drives, but they seem to be the minority. However higher level social creatures have reasons for a lot of the things they do, and no, it's not something made up by the ministry of culture. But somehow I suspect the OP just wants to hear people talk about the subject. That tends to be what we do here at the reference desk, but it'd be nice if we didn't. Any specific question? Shadowjams (talk) 04:45, 22 May 2012 (UTC)[reply]

My question was very specific: "So, do other animals have unusual sexual interests? Are there chimps, for example, who enjoy sadism, necrophilia, pedophilia, or foot fetishes (assuming these aren't typical amongst the species)?" If you don't understand that, or think that it needs to be more specific, feel free to ask for clarification. --140.180.5.169 (talk) 06:25, 22 May 2012 (UTC)[reply]

I'm aware of instances of animal pedophilia (which I define as an adult attempting to mate with a juvenile too young to reproduce) and a documented case of a duck performing a homosexual and necrophiliac act on another. Sadism might include female grasshoppers who behead the male during intercourse, although the motivation is likely not to cause pain. I'm not aware of any foot fetish, perhaps because feet are only covered and hence "taboo", in humans. Other unusual sexual practices include sex with other species and sex with inanimate objects. Masturbation is also common, although this may actually serve a reproductive purpose (to exercise the equipment and keep it working until needed). In social animals, non-reproductive sex may also serve a social purpose, as in the case of bonobos. StuRat (talk) 06:34, 22 May 2012 (UTC)[reply]

Again with the allure of feet, because beauty is in the genes of the beholder too, and these can be more attractive by making them unavailable to viewing. In addition, our visual processes, like those of other animals, do operate upon abstract features of the physique which we often think of as beautiful, which various dress can also accentuate. --Agentundertables (talk) 13:50, 22 May 2012 (UTC)[reply]

I think we have to distinguish between sexually mature and physically mature when talking about whether adult animals have sex with juvenile animals. For example, it is quite possible for a 5 month old female kitten to come into oestrus and get pregnant and have kittens, yet the kitten itself will not become fully grown until it is about 3 years old. Male tomcats will not make the distinction between "kitten" and "cat", merely a cat that is in oestrus or one that isn't. --TammyMoet (talk) 09:41, 22 May 2012 (UTC)[reply]

Any polemics about "unnatural" sexuality suffer from a double fallacy. First, homosexuality is natural; second, nature is devoid of morality anyway. Watch any nature show about grizzly bears, where the mothers spend much of their lives watching out for males who will kill their cubs so that the mother will stop nursing and go into estrus for them. Wnt (talk) 02:03, 23 May 2012 (UTC)[reply]

Odd notation in genetics (greater than symbol?)

In this paper (on royal jelly), specifically in the section "Royalactin changes Drosophila phenotypes via Egfr," there is some form of gene notation using greater than (>) symbols that I am not familiar with and cannot find a non-dense reference on google, or indeed really any useful information at all. I think it may be describing something to do with gene silencing but I'm not sure. Could anyone shed some light on this for me? Examples are:

P0206>dPI3K
P0206>dEpgrRNAi
ppl>dPI3KDN (I know the DN part means dominant-negative as thats noted in the text, but thats it)

Specifically, I'm wondering what the > and d stand for, and what relationship the > symbol denotes for the genes either side of it. Hoping someone who knows about genetics will recognise it. Thanks!! -Zynwyx (talk) 20:37, 21 May 2012 (UTC)[reply]

I'm not sure exactly, but I can tell you that the thing on the left is not a gene, it's a line -- i.e., a group of animals that are either identical genetically or at least very similar. Looie496 (talk) 02:27, 22 May 2012 (UTC)[reply]

P0206 is a p-element insertion site, and the greater-than symbol is used to indicate that gal4 is present at that site (I have no idea who came up with that notation or why). The "d" simply indicates that the gene that follows is the Drosophila version. Someguy1221 (talk) 04:48, 22 May 2012 (UTC)[reply]

Thanks for the responses. Now that I read closer it mentions it in the text Aug21-Gal4 and ppl-Gal4 as two lines used with specific Gal4 tissue expression. I knew ppl was a gene (pumpless), and all of these are examples are italicised in the text so I was assuming they stood for with genes. Some more examples:

Aug21>dEfgrRNAi
ppl>royalactin
act>royalactin
rho>royalactin

So would I be right in assuming the letters on the left denote a genetic line with a Gal4 UAS at/near that locus? And would the > imply then that the gene on the right replaces the gene on the left, so that the gene on the right is expressed in a Gal4 study instead of the gene on the left, or are both genes present? Also would anyone know where I could find more notation on genetic notation (including this >d stuff)? I'm guessing the >d is specific to Gal4 studies though now. Cheers -Zynwyx (talk) 08:39, 22 May 2012 (UTC)[reply]

A much more common notation would be rho::royalactin, which would indicate that the RNA-coding sequence for royalactin is being driven by the promoter for rho. So to me this is reminiscent of that notation except > is used instead of :: to indicate that the driving is occurring indirectly through Gal4/UAS. Now, there's a question of how the thing was made, and for that you have to dig through the methods and references, because the notation does not make it obvious. In the case of P0206>, gal4 was shoved into that position and possibly knocked out whatever gene was original driven by that promoter. But in the case of rho>, I'm going to assume they constructed it denovo and did not do anything to the original gene, since rho knockouts have severe, sometimes lethal phenotypes. No idea where you'd learn more about notations though, aside from asking here and other places. Someguy1221 (talk) 16:04, 22 May 2012 (UTC)[reply]

d stands for Drosophila (abstract: "Drosophila Egfr interference (dEgfri)"). I think Someguy dealt with the rest. Wnt (talk) 21:53, 23 May 2012 (UTC)[reply]