Wikipedia:Reference desk/Archives/Science/2013 November 18

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November 18

Climate of Korea

My mental image of the Korean War is that of soldiers spending months and months in snow-filled trenches, freezing off half their extremities as they wait for the weather to get warm enough for combat. The climate section of Geography of South Korea would seem to back up my idea, talking about "Winters are usually long, cold, and dry", but the specific data in Climate of Seoul sounds far warmer and more hospitable than my mental image or the picture created by the first article's climate section. What's going on? What's the true situation? Nyttend (talk) 02:35, 18 November 2013 (UTC)

Well, Seoul is close to the Yellow Sea, and being near a large body of water will tend to warm and moisten things up in winter, if the prevailing wind direction comes in off the water (unless the water freezes over, and I don't think it's far enough north for ocean water to freeze solid there). So, that's my guess as to why it might be warmer than the interior, in winter.

Also, during a war people (both soldiers and refugees) tend to be far more exposed to the environment. So, a temperature which is just fine if you are in a house becomes unbearably cold if you are in a flooded foxhole. StuRat (talk) 04:58, 18 November 2013 (UTC)

Finally, the cold weather was a major factor in the Battle of Chosin Reservoir, which may have been the images that you were thinking of. Not only is this in the far north of North Korea, close to the border with Manchuria, but the reservoir itself is over 1,200 metres (4,000 feet) above sea level and much of the fighting was on higher peaks and passes. The Environmentallapse rate allows you to calculate a reduction in ambient temperature of 6.49 °C per 1,000 metres of altitude, plus whatever windchill you get in a high mountain pass. Alansplodge (talk) 09:24, 18 November 2013 (UTC)

BTW, the figures in the climate table that you linked are certainly cold for a climate described as Humid subtropical. The average winter temperatures are lower than Copenhagen for instance. Alansplodge (talk) 11:43, 18 November 2013 (UTC)

Also, don't forget that the early '50s were at the very end of a short-term global colding trend (which started in the mid-'30s and was at its peak in 1944 -- that was the coldest year of the 20th century), so temperatures worldwide were lower than average. 24.23.196.85 (talk) 07:34, 19 November 2013 (UTC)

Naming Be
₆N
₄, additively

Following 2005 inorganic IUPAC additive nomenclature, is the following a correct name for [Be]=N[Be]N([Be]N=[Be])[Be]N=[Be]?

μ₃-nitrido-1:1':1"κ³N-tris(μ-nitrido-diberyllium)

Plasmic Physics (talk) 02:41, 18 November 2013 (UTC)

Wow. This is not my expertise, but there's some coverage of this at [1] but this is... remarkable. So you have a single nitrido (N) bridging three Be-N-Be units (the μ-nitrido-diberyllium). The κ³ indicates the N is linked three times from N (where else?). I suppose the 1:1':1" is a specification of where it links to. But I don't know if the IUPAC rules really require or allow that kind of precision about where a nitrogen is linked from when there's one atom, or so much detail about the three units it links to when it's just tris()... it all seems so absurd. Wnt (talk) 08:46, 18 November 2013 (UTC)

I'm also using the 2005 Red Book, but I was using IR 9.5.2.1, specifically comments surrounding example 8. Plasmic Physics (talk) 12:00, 18 November 2013 (UTC)

Please help, Heat transfer coefficient of the external fluid flowing steadily over a horizontal plate

I have read the article "Heat transfer coefficient", only found fluid flowing over horizontal plates (not a plate). Can someone give me an equation on the case of one plate. Many thanks :) SongJie@NTU (talk) 14:23, 18 November 2013 (UTC)

If you're referring to Heat transfer coefficient#External flow, Horizontal plates, the equations seem to describe a single plate (in four different scenarios), in spite of the section title. If that doesn't meet your needs, could you be clearer about what your needs are? Looie496 (talk) 16:04, 18 November 2013 (UTC)

How to make adult stem cells totipotent?

Is there a way to make adult stem cells totipotent and therefore provide an alternative non-controversial method of making totipotent stem cells? 164.107.102.191 (talk) 16:48, 18 November 2013 (UTC)

See our article Induced pluripotent stem cell, and these science articles in Science [2] and Nature [3]. It is not entirely clear to me how these are limited from being "totipotent" (e.g. is there some target cell type that they cannot become?), but maybe someone else can help clear that up. SemanticMantis (talk) 18:02, 18 November 2013 (UTC)

At least as concerns mammals, pluripotent cells can differentiate to form any cell lineage of the body, whereas totipotent cells can additionally form placental tissues [4]. For most biomedical research applications I would imagine there would be little difference (i.e. if you don't want to study placental tissue it doesn't matter), and in any case human stem cells generated "traditionally" (i.e. human embryonic stem cells) are pluripotent rather than totipotent. Equisetum (talk | contributions) 22:56, 18 November 2013 (UTC)

Also keep in mind it can just be a matter of evidence. In order to show the cells are truly totipotent you need to actually show them becoming every tissue type; but even making a chimera out of them can leave open a crack of doubt (since the natural cells might take over some fate they fail to adopt). Wnt (talk) 12:32, 20 November 2013 (UTC)

physics gravittation

In the derivation for gravitational potential energy, we consider the work done by agent in bringing a particle from infinity is a constant for small displacement dx. but once the particle is in the gravitational field, the gravitational force done by an agent will reverse direction. in that case the work done by the agent is first positive and then becomes negative. do we really consider both the positive as well as the negative work? — Preceding unsigned comment added by 120.62.184.196 (talk) 16:56, 18 November 2013 (UTC)

I don't fully understand your scenario, but if you bring a point into a gravity well close to a planet, you'll get negative work out of it that you can use for kinetic energy, annihilating settlements from space, whatever you'd like. Now if you take it away again, out of the well, do you keep that energy, or do you have to give it back? If you don't count both positive and negative work, does that mean you have a plot of the energy you've extracted/put in that abruptly turns into a flat line at some point? Nature doesn't much like flat lines with sharp corners. So my assumption is that you need to count positive and negative, but depending on exactly what you want to calculate, you might end up defining your number differently. Wnt (talk) 17:14, 18 November 2013 (UTC)

direction of Jupiter spot rotation

which direction does Jupiter spot rotate?--Akbarmohammadzade (talk) 17:32, 18 November 2013 (UTC)

Our article is at Great Red Spot, and says "The GRS rotates anticlockwise, with a period of about six Earth days." SemanticMantis (talk) 18:04, 18 November 2013 (UTC)

Enforced neoteny

As many animals become unsuitable as pets once they reach adolescence, and at the very least need to be castrated/spayed to make them manageable, is there any way to keep them young via drugs ? (Even if such drugs are prohibitively expensive when used for people, they might be offered more cheaply for animals, as many are.) StuRat (talk) 19:45, 18 November 2013 (UTC)

Do you mean freeze the aging process, or do you mean keep the pets small? 140.254.229.160 (talk) 21:15, 18 November 2013 (UTC)

You'd be looking at pituitary and genital surgery to remove the source of growth and sex hormones that cause puberty and increase in size. μηδείς (talk) 22:03, 18 November 2013 (UTC)

That may keep the pets small and infantile, but the pet itself may still age regardless in terms of how the other organs will wear out. 140.254.229.160 (talk) 22:10, 18 November 2013 (UTC)

I very much doubt Stu is asking about how to keep them young as in not old. Rather, the obvious issue is immature versus mature. Immature primates make good pets. Not so much so after puberty, and the same for most other wild animals. μηδείς (talk) 22:17, 18 November 2013 (UTC)

Ideally they would stop aging entirely, but I don't believe that's possible. What might be possible, though, is to prevent them from developing adult traits as they age. Yes, neutering them is one method, but I was asking if any drugs are available which can do this, as well. One option might be to prolong their juvenile state, but eventually stop the drugs and allow them to mature naturally. StuRat (talk) 03:48, 19 November 2013 (UTC)

Failure to develop in size and maturity naturally is caused by the lack of a hormone or a receptor for it. We can then possibly supply the missing hormone (not a missing receptor). But we don't usually give a drug to compete with or block a hormone. Such a thing is entirely possible, but were not at the stage where we can target such drugs to knock out certain types of development without possibly incurring serious, if not lethal side effects. At this point, physical removal of the relevant organs is the only practical option. For example, when my grandfather had terminal stage prostate cancer, they castrated him and put him on estrogen, which competes in some effect with testosterone, but would not entirely have masked it. I suggest looking at treatments for this and breast cancer and testicular cancer as well as acromegaly to see if any chemical treatments have the effect you want. μηδείς (talk) 18:10, 19 November 2013 (UTC)

Well, we've enforced neoteny through selective breeding of most out our domestic animals. See e.g. Neoteny#Domestication, Origin_of_the_domestic_dog#Neoteny_in_the_rapid_evolution_of_diverse_dog_breeds, Cat#Sociability, and even Self-domestication#Foxes. If there were currently any reliable way to push this trend further via drugs, rest assured that we would be inundated with advertisements for permanent kittens ;) SemanticMantis (talk) 22:32, 18 November 2013 (UTC)

A boy across the street from me in the 70's was famous for making permanent kittens. Until they stopped buying him replacements. μηδείς (talk) 02:15, 19 November 2013 (UTC)

Castrati used to be common. Had interesting side effects. Different than eunuch --DHeyward (talk) 07:25, 19 November 2013 (UTC)

From Chambers 20th Century Dictionary: Eunuch - means a castrated (ie testicles removed) male, especially one castrated before hormonal development; Castrati - means a male castrated before hormonal development and trained to sing. So no difference except that a castrati can sing, but a eunuch wasn't necessarily, and typically was not, trained to sing. So no real difference. 120.145.154.249 (talk) 15:39, 19 November 2013 (UTC)

OK, I know that this is not the language desk, but please, there is no such thing as "a castrati". --Trovatore (talk) 09:01, 20 November 2013 (UTC)

There must be, it's in the aforementioned dictionary. 60.228.253.116 (talk) 12:38, 20 November 2013 (UTC)

You're missing the point. Castrati is a word, but there is no such thing as a castrati, just as there is no such thing as a criteria, a phenomena, a bacteria, a biscotti, or a dice. --Trovatore (talk) 17:27, 20 November 2013 (UTC)

What you want is an axolotl, the Peter Pan of the pet world, but not so cuddly. Richard Avery (talk) 15:30, 19 November 2013 (UTC)

Axolotls can apparently be made to metamorphose into adults by giving them iodine, which is sort of the opposite of what Stu is asking for here ... maybe he'd like a functionally immortal pet Turritopsis_dohrnii ? SemanticMantis (talk) 16:34, 19 November 2013 (UTC)