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November 9

Falling into a black hole

Suppose an astronaut in a modern spacesuit gets teleported to 10 Schwarzchild radii from an active galactic nucleus, inside the accretion disc. How long does she survive? Will the hot gas in the accretion disc cook her to death? Would the X-rays and gamma rays kill her within a few hours? Or will she survive long enough to be ripped apart by tidal forces?

I know that a quasar's accretion disc is extremely hot, but by earthly standards, I think it's still a near-vacuum. Hence my confusion about the survivability of the environment. --50.46.159.94 (talk) 05:42, 9 November 2014 (UTC)

The pressure caused by the heat alone is a breaking force a significant fraction of the inward desire. In Jupiter, where the forces are exactly balanced, it's hotter than the surface of the Sun and pressurized enough to turn hydrogen metallic and the ionizing radiation would kill a human in short order. A Cessna (a small airplane) will vaporize on the surface of the Sun within 1 second, according to xkcd what if, and the surface of the Sun is only 0.001 times the density of air and only partially surrounded by opaque plasma. The gravity, heat and X-rays is far above this at the event horizon of a black hole, so I would guess it's not survivable. Also, if the black hole is huge enough, tidal forces would not be able to kill. However, fuzzball theory mentioned in a previous thread on black holes a few weeks/months ago states that in that case the body substance would be disintegrated to quarks, gluons etc. and join a ball of string extremely instantly (within a few Planck lengths at 670 million miles an hour). In that case tidal disruption is impossible. Sagittarian Milky Way (talk) 09:09, 9 November 2014 (UTC)

I'd like a further explanation of the pressure at the center of accretion disks. I was just looking at this in the very different context of a Herbig-Haro object where a protoplanetary disk spits out a stellar jet in one or two directions along its axis. But the situation seems sort of the same: gravity pulls all this material in, it "piles up" somehow, and then it gets shot out in jets along the direction the material isn't accreting from. But how much does it "pile up"? And why doesn't it find a way to pile up in a more typical spherical shape rather than reaching escape velocity? And above all, how much actual pressure are we talking about? Is this (in your case) a black hole with an atmosphere??? Wnt (talk) 14:58, 9 November 2014 (UTC)

Bugs?

This split cashew has been roasted and salted for a while, but are these larva?

— Preceding unsigned comment added by DRosenbach (talk • contribs) 16:22, 9 November 2014

Stomped on this one. Have you thought of asking your local Food and Drug Administration office. If they don't have an insect expert at hand, ask them to forward you image to an entomologist. If and when you get an answer, your image could be useful on what ever WP article we have for cashews.--Aspro (talk) 20:04, 9 November 2014 (UTC)

They sure look like larva to me, yes. StuRat (talk) 20:44, 9 November 2014 (UTC)

Yes, maggots. Are they live? Was the nut like this when you opened it, or did you leave it sit out? If they were canned, take them back for a refund. If they were from a local producer let him know. μηδείς (talk) 22:03, 9 November 2014 (UTC)

Think you mean retailer rather than producer (the US imports cashew). Next: “This split cashew has been roasted and salted for a while” so why should they be alive (if they are in fact larva)? Finally: “If they were from a local producer let him know.” So what exactly do you think he is going to do about it!!!? If you have ever worked in the retail business, you will know that customers are forever coming into complain. If a retailer followed up each ever complaint... Do you think the business proprietor or manager would have any time left over to get around to serving any customers? That is why I suggested that the OP goes to his local FDA. That is what they are their for and they can call on expert that can provide learned analyses. Cashew are boiled or steamed so are safe in this respect, but they would realize that a US citizen deserves a proper answer as to what he is consuming when he has doubts. It also gives the FDA a rare opportunity to assure John Doe's that they (the FDA) is doing a good job (cough, cough).--P.g.champion (talk) 21:34, 10 November 2014 (UTC)

I don't think the FDA cares about every worm in an apple. The right person to complain to is obviously the manufacturer of the product (or at least who is listed on the container), who probably has the option to choose which farm, inspect the nuts at the time of sale, etc., and is powerfully motivated not to have this happen too often. Wnt (talk) 15:58, 11 November 2014 (UTC)

Verily. Cashew may be advertized as Raw but it is very unlikely that they have not been heat treated due to presence of urushiol in completely raw nuts -thus the heat treatment killing any meanies at the same time. So health-wise, one can consider store purchased cashews are safe to feed to pigeons and chipmunks. Otherwise why did Tom Lehrer (and girl fiend) offer peanuts and not cashew to their feathery friends?. [1].--Aspro (talk) 22:22, 10 November 2014 (UTC)

Maybe because peanuts are far cheaper, at least in the US ? This is why we have the phrase "Working for peanuts", meaning very little money. StuRat (talk) 16:39, 13 November 2014 (UTC)

Or just eat the nuts, maggots and all. Once they are cooked they are harmless.

Jack, eating rotten cheese, did say,

Like Samson I my thousands slay;

I vow, quoth Roger, so you do,

And with the self-same weapon too.

Greglocock (talk) 23:43, 9 November 2014 (UTC)

symbol of Diploma Supplement what does it say?

I saw on this site (Medical university) that they show the symbol of "EU" (on the side of the side in the slide: accreditation) ,and I don't understand what it says. If I get a diploma of this university, can I work with it in Europe without to pass any exam? and what it says about the university? (every university in Ukrane can do the same procedure?) Thank you 5.28.158.164 (talk) 17:17, 9 November 2014 (UTC)

No. If you click on the logo it tells you that it is "A document describing the knowledge and skills acquired by holders of higher education degrees. It provides additional information to that included in the official degrees / diplomas and/or transcript, making it more easily understood, especially by employers or institutions outside the issuing country" and it is not "an automatic system that guarantees recognition" Richerman (talk) 21:37, 9 November 2014 (UTC)

The logo in question is that of TEMPUS, an EU organization that "supports the modernisation of higher education in the EU's surrounding area." This is the relevant page from their website. Tevildo (talk) 21:44, 9 November 2014 (UTC)

Er, no it doesn't seem to be. There is a Tempus logo there also, but the one in question is the Europass logo from the European Centre for the Development of Vocational Training. Richerman (talk) 22:00, 9 November 2014 (UTC)

What does it say? (I mean about Tampus) 5.28.158.164 (talk) 01:57, 10 November 2014 (UTC)

TEMPUS is an organisation dedicated to improving the standard of educational qualifications across Europe. Richerman (talk) 10:22, 10 November 2014 (UTC)

How complex is the brain of a common shrimp?

Mantis shrimp can rupture glass aquaria with a blow of their claws.

In other words, I know it's more of a fused ganglion thing going on, but is there some measure of average complexity for them, eg. the total number of neurons or an encephalization quotient figure or something? I'm unable to find much of anything on the subject and the only crustacean listed on the wiki page listing animals by number of neurons is the lobster. — Preceding unsigned comment added by 142.105.176.81 (talk) 20:24, 9 November 2014 (UTC)

Shrimp is not an official biological category, so you have to be more specific. See harlequin shrimp which live in mated pairs, and mantis shrimp for one mean critter. The latter are believed to have perhaps the most elaborate visual system of any animal, being able to se up to 16 primary colors, compared to our three. μηδείς (talk) 03:04, 10 November 2014 (UTC)

"Shrimp" can mean different things in common language and science, but mantis shrimp aren't even Decapoda, so they're not shrimp in any scientific categorization. As explained in our article, shrimp usually refers to the grouping of Caridea and Dendrobranchiata suborders of Decapoda when used in scientific contexts. Anyway, here's a recent article titled "Brain evolution in decapod crustacea" [2]. It doesn't give an ecephalization quotient, but it has other measures of the size and complexity of the brains of shrimp-ish organisms. It would be a good starting place for anyone interested in shrimp brains. SemanticMantis (talk) 17:51, 10 November 2014 (UTC)

Nevertheless, my Mantis shrimp are better than your shrimp, Mantis. μηδείς (talk) 18:19, 10 November 2014 (UTC)

Bisulphate of baryta

What is Bisulphate of baryta? The substance is named in Conan Doyle's "A Case of Identity", and it appears in an 1858 chemistry book, but I can't understand what composes it. The latter source

gives a reaction that includes it:

RO [note that there's a line over the "R"; I'm not sure what this conveys], BaO + S²O⁶, 2HO = RO [again, line over "R"), HO + S²O⁶, BaO, HO.

Is it a mixture of barium oxide and S2O6? I want to create it as a redirect if we have an article on the subject. Nyttend (talk) 20:36, 9 November 2014 (UTC)

By looking at the name, it is the same as barium bisulfate Ba(HSO
₄)
₂. Plasmic Physics (talk) 20:55, 9 November 2014 (UTC)

According to [3] it is Ba(HSO
₄)
₂ – barium bisulphate. Ruslik_Zero 20:57, 9 November 2014 (UTC)

That reference claims it exists. Another reference is at 100 Chemical Myths saying it does not. Graeme Bartlett (talk) 00:26, 10 November 2014 (UTC)

Looks like it's CAS# 25105-31-1; SciFinder has a several reports for its synthesis, including X-ray crystallography and vibrational spectroscopy in 1970s–1990s. DMacks (talk) 09:44, 10 November 2014 (UTC)

Looks like DMacks has the CAS number, but here's a public web link to a structure: [4][5] which is simply Ba 2(H2O4S). Simply, that is, until you go to place the positive charge on the barium... The story is at s:A Case of Identity; though I didn't read it I only see a brief mention of it as being a compound Holmes identified, so there are no 'claims' to confirm about it. The OP's chemistry book source [6] has an unfamiliar way of dealing with chemical formulas, but it should be clear that no named atoms but barium, sulfur, oxygen, and hydrogen are present, consistent with "barium bisulfite". It further says that when the substance is heated on platinum, "fumes of sulphuric acid are evolved in great abundance", leaving neutral sulphate behind. Barium sulphate is BaSO4; subtracting that from the above formula yields H2SO4 in equal proportion. So we have one Ba+, one neutral H2SO4, one bisulfate HSO4- ... and a neutral hydrogen left over?? Hmmm. It would be tempting to suppose that you could have true barium bisulphate, i.e. 2Ba+ 2HSO4-, and you can heat that to liberate 1 H2SO4 and leave behind 2 BaSO4. However, it is hard to believe that someone would mistake the amount of sulfuric acid liberated per barium ... especially to think there is more produced than the compound possesses. Either there's a silly clerical error or ... something odd. Anyway, I think we see what kept Sherlock busy for a day. Wnt (talk) 16:50, 10 November 2014 (UTC)

Why does weather anomalies happen?

Hi,
Last year there was a great storm in NY, and the temperature dropped severely.
My question is why those anomalies happen? Exx8 (talk) 20:50, 9 November 2014 (UTC)

You ask an extremely broad question, so we can't provide specific answers. Have you read our Weather article? It may answer your general questions. If you want answers on a specific storm, we may be able to provide more details. Nyttend (talk) 20:56, 9 November 2014 (UTC)

The sort of extreme events you are referring to are called Global weirding by some scientists, see:[7] and [8]. Much of it seems to be caused by climate change affecting the Jet stream. Richerman (talk) 22:36, 9 November 2014 (UTC)

The most common reason for a rapid temperature drop is when a cold front arrives. Rain can also lower the temperature quickly, since it forms where the air is usually much colder. And temperature naturally drops as the Sun sets, so a cold front, with rain, arriving at sunset tends to magnify the effect. There are also more rare reasons for the temperature to drop suddenly, such as downbursts/microbursts. StuRat (talk) 01:30, 10 November 2014 (UTC)

An anomaly, in this context, is something that's rare and hard to predict. Rare weather events come about because of a coincidence of several not-so-unusal things happening at the same time. So slightly elevated temperatures in one place with high humidity someplace else and maybe particular wind patterns at some other place...none of them very unusual individually...come together to make something that is very unusual. These events are often unpredictable for much the same reasons. Also, weather patterns are inherently chaotic - in the mathematical sense of that word. SteveBaker (talk) 02:06, 10 November 2014 (UTC)

November 10

Efficiency of body at energy conversion

I want to find out how efficient a person's body is at converting the chemical potential energy of food into mechanical work (eg. lifting a weight). The article food energy says the food energy realised by respiration is converted to muscular output with roughly 20% efficiency. But this leaves out earlier stages in the chain: presumably not all of the potential heat of combustion of food is realised in respiration; and also I think about 10% of the energy from food has to be `ploughed back', so to speak, into the work of digesting food, so there's another 10% energy loss. I think there may be other inefficiencies.

Then there's that whole thing about, if you hold a 100 pound barbell over your head for an hour, that's not `work' according to the physics definition of the term because there's force but no distance; but it certainly is `work' according to the common English sense of the word – rather hard too, in fact.

Finally, how much mechanical work can a reasonably fit person do in a day? (Eg. in joules.) How about a top athlete? -- Communpedia Tribal (talk) 05:24, 10 November 2014 (UTC)

According to Horsepower#History_of_the_unit, a reasonably healthy human can burst at 1.2 horsepower (890 W), an athlete at 2.5 hp (1,900 W). A healthy human can sustain 0.1 hp (75 W) indefinitely, and an athlete 0.3 hp (220 W) for a few hours. Also note, that the body normally has to burn food just to keep you warm (Thermogenesis#Non-shivering_thermogenesis); if you are exercising heavily then the waste heat is more than enough for warmth, so that saves the body from using food for warmth. CS Miller (talk) 10:31, 10 November 2014 (UTC)

• The net thermal efficiency of a healthy human is about 20%. See also, basal metabolic rate. μηδείς (talk) 18:17, 10 November 2014 (UTC)

What makes this difficult to answer is that "efficiency" is defined in terms of useful work done (our article says: "Efficiency generally describes the extent to which time, effort or cost is well used for the intended task or purpose.") - but the definition of "intended" or "useful" is tough to nail down here. For example, when you run...the energy conversion into kinetic energy is one measure of efficiency - but the muscles generate heat, and as warm-blooded creatures, generating heat is "useful" - so do you count the incidental heat generated by the muscles when running as a part of the useful energy or as a part of the waste energy? Clearly it depends on the situation. In a hot climate, that extra heat is a major problem because it has to be removed from the body somehow - but in a cool climate, we might deliberately use our muscles to increase heat production. So when we're shivering, the kinetic energy generated is "waste" and the heat produced is "useful" - which is a complete reversal from the situation when we're running.

So until you can meaningfully partition wasted energy from useful energy, calculating efficiency is difficult.

That gets worse when you think of things like the energy consumption of the brain. Our brains use about 25% of our energy production...but (for example), a lizard gets by with only about 2% of it's energy devoted to brain functions. If we're simply trying to run fast in a straight line, then that 25% consumption is nearly all wasted because it should be possible to run in a straight line using only 2%...but if we're actively navigating to find the shortest route then thinking more equates to running less, so the brain's contribution to getting from A to B is just as "useful" as piling on more kinetic energys - and so it should be counted. But what about if we're using the time to compose poetry or design the next high-tech widget...then how do you account for that brain energy?

So, (as is often the case here) we need to tie down our terms rather more precisely in order to deliver a reasonable answer.

SteveBaker (talk) 19:01, 10 November 2014 (UTC)

The brain using 25% of our energy is a common trope for which you provide no source, SteveBaker. Is our article wrong when it says the brain uses about 20%, while the liver uses about 30, and the heart only 7? μηδείς (talk) 21:25, 11 November 2014 (UTC)

Sources I've looked at are all over the map from 20% to 30% - it probably depends on the individual, and on how much brain activity is going on during the period that they're observed. It's certainly not a precise number. At any rate, the precise answer doesn't affect my answer in any way - so I really don't see the need to quibble over 5%. My point is only that measuring "efficiency" entails asking whether all of the energy consumed by the brain is "useful" or waste...and that clearly depends on the task we're measuring the efficiency of. "How efficient is the body at running marathons?" is not remotely the same question as "How efficient is the body at solving quadratic equations?". It doesn't matter whether the number is 20% or 30% or someplace in between - that's not the question here. SteveBaker (talk) 05:11, 12 November 2014 (UTC)

The value of the electron in the world of science

Did it true, that since the discovery of the electron world science had not progressed, because the electromagnetic electronic balance of all elementary particles is always been the same (equal) and always been constant?--Alex Sazonov (talk) 09:32, 10 November 2014 (UTC)

No. Science has made plenty of progress. There is a fringe theory around that says that once a physical quantity is measured then it causes other similar measurements to come up with the same value. Some kind of precedent setting. I don't know what this is called and I don't trust it. Graeme Bartlett (talk) 12:17, 10 November 2014 (UTC)

(ec)No, not at all. There is plenty of science that is progressing all the time. E.g. all of computer science, or special relativity, or the decoding and application of DNA. Or, to stay subatomic, the discovery of quarks (with non-integer charges) and the whole standard model.--Stephan Schulz (talk) 12:23, 10 November 2014 (UTC)

Pretty much all of modern geology has progressed a lot, starting with plate tectonics, which is the Sine qua non for geology. Plate tectonics started as a concept some 20 years after the discovery of the electron (though under a different name) and made major leaps forward in the 1950s and 1960s. Nearly all of meaningful discoveries in meteorology, astrophysics, psychology, etc. etc. came about in the 20th century, while the discovery of the electron occurred in 1897. The discovery of the electron was certainly very very important, but it isn't like it was the only thing that happened in science in the past 120 years. --Jayron32 13:01, 10 November 2014 (UTC)

Atomic electric charge of all elementary particles is always been the same, so it turns out, that in the natural nature are always been only once electrons!--Alex Sazonov (talk) 13:36, 10 November 2014 (UTC)

Except quarks. --Jayron32 13:59, 10 November 2014 (UTC)

And, to be pedantic, protons and positrons. --Stephan Schulz (talk) 15:00, 10 November 2014 (UTC)

Atomic structure of all elementary particles is been the same (universe), so we can conclude that in the natural nature are always been only once electrons, as ideal atoms.--Alex Sazonov (talk) 17:28, 10 November 2014 (UTC)

That statement makes no sense whatsoever in English. AndyTheGrump (talk) 17:32, 10 November 2014 (UTC)

It makes even less sense in the 3000+ other languages of the world. --Jayron32 17:33, 10 November 2014 (UTC)

You might be interested in One-electron_universe. SemanticMantis (talk) 17:42, 10 November 2014 (UTC)

Electrical properties in the natural nature had only once electrons!--Alex Sazonov (talk) 17:47, 10 November 2014 (UTC)

No, they didn't. Saying it over and over again doesn't make it so. --Jayron32 17:52, 10 November 2014 (UTC)

Are you thinking of the plum pudding model, a now-discredited model of the atom? It suggested that the atom consisted of electrons floating in a goo, without any other specific components. Meanwhile, Graeme Bartlett, what do you mean? It sounds like you're describing a researcher with a form of confirmation bias, whereby he's prejudiced toward finding results similar to the one he already got. Nyttend (talk) 20:33, 10 November 2014 (UTC)

I heard it on a podcast recently, but I can't remember exactly which one, or who was the proponent. It was more of a theory of reality. It said that various measurement values were indeterminate until they were first measured and thereafter all future measurements would come back the same. Graeme Bartlett (talk) 22:39, 10 November 2014 (UTC)

The OP's rantings remind me more of Prout's hypothesis, which was actually considered a reasonable conjecture until disproven, which held that all elements were composed of aggregations of hydrogen. Prout proposed his hypothesis because all pure isotopes were multiples of the mass of hydrogen-1 (protium), which implied that hydrogen was in some way fundamental. He was wrong, but in interesting ways. Prout's hypothesis provided an important step in the discovery of the proton and neutron, which (to a rough approximation) DO weigh the same as hydrogen does, and explain why Prout's hypothesis works. Still, it has nothing to do with electrons, and the OPs repeated insistence that everything is somehow made of electrons (it isn't), or that electrons have the smallest fundamental charge (they don't) or that all science since the discovery of the electron is somehow directly derivative of it (it isn't). --Jayron32 23:15, 10 November 2014 (UTC)

Are Mark 60 CAPTOR naval mines being phased out?

This site[9] says: "The CAPTORs are gone, and the SLMMs will be phased out in 2012." in reference to the Mark 60 CAPTOR naval mines. Is this true? I can't find any other collaborating sources. I don't usually trust random online sources, but the author, Scott C. Truver, is on the editorial board of Naval War College Review. WinterWall (talk) 11:39, 10 November 2014 (UTC)

I think this is better asked at Humanities, because notions of chivalry, budget, and perhaps international law are involved. How gone is "gone" is another question for them to chew on. The science aspect I see in the source is Suggestions that the Navy acquire modern foreign mines have been met with “not invented here” indifference. Here it might be worth pursuing what technological improvements the "modern" mines have that the U.S. ought to copy. Wnt (talk) 17:01, 10 November 2014 (UTC)

I did a little reading on the topic; and my conclusion was, roughly summarized: I don't know. But I found some good reading material!

Our Department of Defense keeps a pretty tight lip on its capabilities regarding undersea warfare. You can read about the Navy Undersea Warfare Center and the Naval Mine and Anti-Submarine Warfare Command, but ... there's not much information on technologies or capabilities. Compare this to the websites of the Air Force or the Army, where the public websites advertise all kinds of nifty specifications about airplanes and armored vehicles and guns, arguably for the purposes of recruitment. This is consistent with everything I know about submarines: they're pretty much Top Secret, so there's no good reason to make noise about even their mundane factual details.

I went to the website of the Department of Defense to see if there's any public information - budgets or press releases or speeches. There's a 1996 speech: Three Musts for Affordable Naval Mine Warfare, by Paul Kaminski - who would have had a pivotal role in executing the national defense policy for naval mine technology. And if you search the public Defense Department budgets, there are line-items scattered among the results for naval mine warfare technology development and system acquisition. So this is an ongoing effort; but it's not highly publicized. It is probable that the Navy can not justify losing a capability, even if that capability has no immediate application to any existing conflict.

Even still, it seems cheaper and easier to deploy undersea mines from surface ships and aircraft. There are no shortage of news reports on that: for example, the P-3 Orion Practices Aerial Mine Laying in Gulf of Thailand. To deter enemy mine-laying, there are a variety of effective techniques, from aerial surveillance to diplomatic efforts. When possible, the Navy would prefer to keep its submarines out of the spotlight, because their much more critical role - second strike - depends on keeping them out of combat.

Finally, I would direct you to read this statement from the Department of Defense. In 2014, the United States made a critical policy statement, reversing many years of prior policy: "The United States will not produce or otherwise acquire any anti-personnel landmines in the future." On the whole, the Defense Department has decided that antipersonnel land-mines are not a good thing, from a defense standpoint. They bring bad publicity; they are hazards to friendly forces; and mines persist for a long time after the conflict is over. When confronting conventional state-based opponents, it is easier to enforce treaty-compliance through diplomacy, and avoid mine-warfare by "gentleman's agreement;" and when fighting a non-state actor in asymmetric warfare, there is little advantage in deploying the mines ourselves; in fact, our biggest problem in the last few wars has been that the asymmetric opponent had far too easy access to land mines and improvised explosives. The reversal of American policy is huge - landmines are a very big problem throughout the world, even in places where conflicts "ended" many years ago.

Important to note, though, that anti-vehicle landmines and naval mines were not mentioned in the policy statement. Evidently, the Defense Department had no comment on those topics.

Nimur (talk) 16:46, 11 November 2014 (UTC)

Thanks, guys. WinterWall (talk) 14:08, 13 November 2014 (UTC)

Resolved

High humidity in refrigerator

If the relative humidity inside a refrigerator is high (in the high 80s range), what could be the cause? --173.49.12.187 (talk) 13:02, 10 November 2014 (UTC)

Here are some possible answers to your question. --Jayron32 13:12, 10 November 2014 (UTC)

I have that problem in my fridge, too, in the summer, when the house air is humid. In fact, water drips from the divider between the top freezer and bottom fridge. I simply put a bowl under where it drips and dump it regularly. I think of it as a fridge plus dehumidifier. The fact that it's dependent on house humidity implies that keeping the humidity in the house low will solve the problem, too. StuRat (talk) 16:36, 10 November 2014 (UTC)

My parents' fridge has a little heating element which when turned on evaporates the condensation that otherwise drips from the freezer to the fridge. She gets upset if it is activated, and then accuse people of spilling water on the refrigerator door! My OR would be to leave a jar of baking soda in the fridge as a desiccant and stir it occasionally until it cakes up. This is actually a recommended use by the manufacturer (see the box) to keep the fridge "fresh". μηδείς (talk) 18:09, 10 November 2014 (UTC)

Baking soda is most probably the most cost effected method normally, as it is cheap. Yet, if one has very high humidity then maybe Blue Indicating Silica Gel might be better Blue Indicating Silica Gel. One rejuvenates it in the oven. If on the other-hand, (say for augments sake) one's daughter's boyfriend always raids your fridge every time you go out (in the hope that by by leaving them together – alone- without Mom and Dad's eyes following and analyzing their every interaction; in the faint, faint hope that they ignore everything the have seen on TV and might discover the same magic- Oh that's for another time). Then leave a diaper in the fridge. That has silica gel in it too and will bring down the humidity. Should the boy- fiend see this diaper, then come to terms with the fact that he is probably dating a member of the Adams family, then you're almost home and dry. Suggest however, one uses, unused diapers in the fridge.--Aspro (talk) 23:36, 10 November 2014 (UTC)

The ambient humidity is not the problem. The refrigerator was recently serviced for a different problem. There is another refrigerator in the same area. The relative humidity inside the latter is the 40s. --173.49.12.187 (talk) 02:18, 11 November 2014 (UTC)

You misunderstood me. I'm not saying that a properly operating refrigerator should drip water when it's humid in the room. I'm saying a malfunctioning fridge may only drip when the ambient humidity is high.

Some models of fridge have a drip pan under the fridge to catch drips, so they admit that this is a possibility. But my question is just what is supposed to happen to your ambient moisture ? It enters the fridge each time the door opens, and is likely to condense at the lower temperatures, and it has to go somewhere. A heater to evaporate condensed water and blow it outside the fridge is one way to handle it. Personally I think pouring the waste water down the drain is a better option, rather than using energy to evaporate it and put it right back into an already humid room, where it will again enter the fridge the next time the door is opened. StuRat (talk) 04:52, 11 November 2014 (UTC)

The drip pan is normally mounted on top of the motor/compressor unit, and uses waste heat from it to evaporate the condensate. CS Miller (talk) 12:36, 11 November 2014 (UTC)

Lets break this down into tiny steps: The two fringes may be working at different temperatures. The lower temperature fridge (one would think) has the lower humidity. Second. Humidity meters are notoriously hard to calibrated (unless one has a laboratory grade instrument). Are the same instruments (thermometer, hygrometer) being used to measure both interiors? The average hygrometer bought at the local store are mostly not worth the money. So it one has two they may well not agree with each other.--Aspro (talk) 22:14, 11 November 2014 (UTC)

The two refrigerators may not be at exact the same temperature, but they are not far apart. The humidity measurements were taken using the same digital combination thermometer-hygrometer. Measurements from the same refrigerator were consistent over time. --173.49.12.187 (talk) 04:48, 12 November 2014 (UTC)

Nearest-planet-to-Earth graph

Is there somewhere a graph plotting the Earth–Mercury distance, the Earth–Venus distance and the Earth–Mars distance all against time (for at least a few years around now)? Or is there free data somewhere from which I could build this graph myself? 85.226.205.208 (talk) 18:04, 10 November 2014 (UTC)

This website has utilities that will let you do exactly that, for every planet in the solar system. --Jayron32 18:21, 10 November 2014 (UTC)

FYI, Venus will always be the closest at least once a year, since its orbit is closest to ours, and with its quicker period it laps us at least once every calendar year. μηδείς (talk) 21:57, 10 November 2014 (UTC)

You might find http://www.fourmilab.ch/solar/solar.html to be helpful.

—Wavelength (talk) 22:05, 10 November 2014 (UTC)

Thanks for all the suggestions! I was a little confused as to how to gather data series from those pages, so I ended up writing a little Python script to send repeated requests to the Fourmilab page, and output the distances to a CSV file. I hope they'll forgive me for flooding the server. It made for a very interesting graph indeed! 85.226.205.208 (talk) 12:52, 11 November 2014 (UTC)

Cool, care to share your graph(s)? It would probably be well placed on our Commons, and could be used in a variety of related articles. SemanticMantis (talk) 14:59, 11 November 2014 (UTC)

Certainly! Here is the graph. The font size should probably be larger if it is to be used as an article illustration, but I guess that is easily fixed. I also uploaded the Python code to the image's talk page on Commons, in case someone needs other date spans. If you're more used to Commons categories than I am, feel free to add some. Cheers, 85.226.205.208 (talk) 08:42, 12 November 2014 (UTC)

Thanks! SemanticMantis (talk) 16:20, 12 November 2014 (UTC)

November 11

Copper in homopolar motors

I've noticed that most simple homopolar motors use primarily copper wires in their structures. Is there something specific about copper or is it just because it does not attract magnets? Will a zynk or an aluminium wire work in a homopolar motor then? 128.68.216.15 (talk) 00:19, 11 November 2014 (UTC)

Copper is an excellent electrical conductor. Plasmic Physics (talk) 02:19, 11 November 2014 (UTC)

Yes. I believe silver is a better electrical conductor, but that would cost too much. StuRat (talk) 04:41, 11 November 2014 (UTC)

Copper is also quite flexible, so it survives vibrations better than other metals like silver and aluminium. Silver actually conducts electricity a little better than copper - and for something like an electric motor, the slightly worse conductivity of aluminium would hardly be noticeable. Price is not a small matter - and historically, copper was cheaper than aluminium...but since the world is rapidly running out of copper ore - we'll be seeing aluminium wiring used a lot more than it is right now. SteveBaker (talk) 04:57, 11 November 2014 (UTC)

Copper-clad aluminium wire is also used for some purposes, although often controversially when used for twisted pair data cabling purposes [10] [11]. (It's more established in the high frequency coaxial market.) Also Copper-clad steel although that's not exactly new. I think these examples demonstrate some other advantages of copper such as relating to corrosion or oxidation, although some of them are probably not relevant to the motor case, e.g. Galvanic corrosion, but see our articles also also [12] or other discussions. (As an aside, copper clad wire has some disadvantages too such as the current difficulty separating the metals meaning recycling is difficult [13].) Nil Einne (talk) 11:55, 11 November 2014 (UTC)

How fast would a spacecraft be travelling?

In our article Taurus Molecular Cloud 1, there are a couple of videos that zoom in from a more distant perspective. If a spacecraft were able to travel as the speed depicted in the video, how fast would the craft actually be travelling in the depicted timeframe and distance? 99.250.118.116 (talk) 01:03, 11 November 2014 (UTC)

I don't think the viewpoint is changing at all. It's like the zoom lens on a camera - you're changing the field-of-view of the lens - not physically moving the camera through space. If you were moving from earth to a place where things looked that big without zooming, you'd have to cover most of the the 430 lightyear distance in about one minute. Let's call that 400 lightyears per minute...which in "classical" terms would be about 200 million times faster than the speed of light. Unfortunately, you can't travel faster than light...so that can't happen. But the problem is a bit worse than that. Because of relativity, the faster you travel, the more compressed distances seem to you. So you wouldn't have to travel faster than light to get there that quickly...going somewhere quite close to the speed of light would be enough to get you from here to there within a minute...from your perspective. However, if you were sending those photos back to earth via telemetry, it would take over 400 years, no matter what. SteveBaker (talk) 04:03, 11 November 2014 (UTC)

Note that in any "cloudy" environment, a ship would see changes as obscuring dust moved across the field of view that aren't replicated in the video. Also, in practice moving so close to the speed of light would impose really severe distortions on the field of view. Wnt (talk) 15:49, 11 November 2014 (UTC)

The end of Rosetta (spacecraft)

Rosetta (spacecraft) is in orbit around a comet and it is planned that it will land a probe on the comet tomorrow. The article says the mission will end Dec 2015. At first I assumed that the comet would go near the sun and the Rosetta would burn up, but a bit of research shows that it will only approach to 1.2 AU and will only go out as far as 5.7 AU. We have seen Mars surface explorers keep going in a hostile environment for many years past the original planned mission. At the closest approach there should be no problem with "too much sun." . So why couldn't the mission continue a lot longer than the projected Dec 2015 ending? Is it just a matter of having answered the set questions, and other projects needing attention? It should not need propellant to stay in orbit around the comet. Would there be too little solar power after Dec 2015 to run the reaction wheels from time to time for orientation correction and to keep the computers and heaters going? How about out at 5.7 AU? Edison (talk) 19:14, 11 November 2014 (UTC)

I note that Solar panels on spacecraft says "The Rosetta space probe, launched March 2, 2004, will use solar panels as far as the orbit of Jupiter (5.25 AU)..." How far out from the Sun will Rosetta be in Dec 2015? Edison (talk) 19:27, 11 November 2014 (UTC)

Probably the money that was allocated to keep the ground station operative runs out at the formal end of mission. This has spelled the death of many vehicles. NASA sometimes extends missions - but only when they are generating new science...and it may be that the instruments on Rosetta will have extracted about all they can by December. You only need just so many photographs of a comet. But also, as the craft gets further from the sun, the solar panels produce less and less energy. The specifications say they produce 850 watts at 3.4 AU. When you double the distance, you get one quarter the amount of power...so at 5.7 AU they are probably only generating about 300 watts. It doesn't take much extra distance to make a huge difference to the power availability. As the amount of sunlight reduces, the need to heat the spacecraft to keep the electronics alive increases - so you have increasing demand and decreasing supply. I also wonder whether the spacecraft's orbit is as stable as you imagine - given that the asteroid doesn't have a nice spherical shape - and its' mass is reducing all the time and at unpredictable rates. SteveBaker (talk) 19:59, 11 November 2014 (UTC)

There might be new information as the comet moves away and cools. Will its weak gravity draw back at least a portion of the outgassed vapor and emitted particles, so that they redeposit? If I recall correctly, Rosetta was 19 miles or so from the comet, so its orbit should be less effected by the duck or potato shape of the comet than if it were close by. The comet is putting out huge amounts of water vapor presently (a liter every 15 seconds if I recall correctly). I wonder if passing through the vapor will push Rosetta farther away, or degrade its orbit and bring it in until it hits the comet. Is there any reason Rosetta would not follow the comet indefinitely? Edison (talk) 22:39, 11 November 2014 (UTC)

As Steve suggested, given 67P's small, spatially- and time-varying gravitational field, Rosetta surely needs to expend fuel to maintain even a fixed-distance orbit around it. And this fuel is a factor limiting the mission's lifetime, along with funding. Rosetta FAQ says, Rosetta's nominal mission will end in December 2015 after a total lifetime of 12 years. There could be a six-month extension provided there is fuel remaining, nominal activities are completed by the end of 2015 and additional funds are made available.... A decision on this will be taken in late 2014. And just as an aside: Philae's mission ends in March 2015, because "lander will become too hot to operate" at that distance from the Sun (1.2AU?). Abecedare (talk) 01:10, 12 November 2014 (UTC)

According to WolframAlpha, the target comet 67P/Churyumov–Gerasimenko is currently (12 Nov 2014) just under 3 AU away. On on 31 December 2015 it will be just over 2 AU away, so it is still approaching Earth ---- CS Miller (talk) 11:16, 12 November 2014 (UTC)

Magnets and heat

I've heard that enough heat can ruin a magnet. How much heat are we talking about exactly? For example is it possible to ruin a neodymium magnet by boiling it in a cooking pot? 89.178.237.122 (talk) 20:27, 11 November 2014 (UTC)

This page [14] on a magnet supplier's website says that some neodymium magnets can be be demagnetised permanently at a temperature of 80 °C, so yes, boiling one in a cooking pot might do it, though it is dependant on multiple factors - precise makeup, shape, and exposure to reversed magnetic fields. AndyTheGrump (talk) 20:41, 11 November 2014 (UTC)

In short, no, boiling the magnet won't ruin it. Curie temperature is what you need to reach, i can't see a reference in that article for neodymium but you might be able to google it.Vespine (talk) 22:06, 11 November 2014 (UTC)

Depends on the exact composition of the material. Some Rare-earth magnets are build specifically to withstand high operating temperatures, such as those used in electric motors (e.g. [15]). Mihaister (talk) 23:47, 11 November 2014 (UTC)

3 more magnet suppliers that all state that heating some neodymium-containing magnets above 80 °C may lead to a permanent loss of magnetism: [16][17][18] I very much doubt that they would state this if it weren't correct - why should they invent limitations that don't apply? AndyTheGrump (talk) 00:01, 12 November 2014 (UTC)

Reading the sources, a perhaps important point of clarification is that as I understand it, the loss is only of part of the magnetism (unless you reach the Currie temperature) and that although it is irreversible it sounds like it depends mostly on the temperature, not how long it's held there. By which I mean even if you boil the magnet for 24 hours, I don't think the magnet is going to have no strength left, in fact, it may not be much different from one boiled for 1 hour. The [19] is IMO quite useful here. It ofters some quantification on the irreversible loss for certain magnets above 80 °C. It doesn't really explain why, but perhaps a search for "permeance coefficient" would give more details. Note that the Curie Temperature of these neodymium magnet with maximum operating temperature of 80 °C, may be 310 °C [20]. In both cases (i.e. even if heated past the Curie temperature and all ferromagnetism is lost), as I understand it these losses are irreversible but not permanent. By which I mean you can remagnetise the magnet if you have the necessary equipment like that used to magnetise it in the first place. You need to heat it a lot higher before you damage the magnet such that it can't be remagnetised (without recycling and resintering). Nil Einne (talk) 06:32, 12 November 2014 (UTC)

November 12

Bird identification

I'm cycling into my office every day, and I picked my flat to have a nice ride through several of our beautiful parks. In the last few days, I've met a largish grey bird, sedately stalking around the grass. Can anybody identify it? Its a bit hard to see in the image, but it does have a rather large beak.--Stephan Schulz (talk) 00:05, 12 November 2014 (UTC)

Looks like the familiar great blue heron to my eyes, but the filename says Stuttgart so maybe a grey heron? Wnt (talk) 00:42, 12 November 2014 (UTC)

Definitely a heron, and just a little small (perhaps immature) for a great blue, which I have had the misfortune to see face to face. The grey heron seems to be stouter, and to have a yellow beak and a whiter neck than this bird. There's always Wikipedia:BIRD at which to enquire. μηδείς (talk) 01:07, 12 November 2014 (UTC)

Thanks. Yes, I should have specified the location (Stuttgart, Germany) explicitly (in fact, I planned to, but then forgot - it was just past midnight ;-). Heron is a very plausible suggestion (and in Germany then likely a grey heron). It was a bit small, but it might be a young one. --Stephan Schulz (talk) 13:09, 12 November 2014 (UTC)

Where have all the slugs gone?

I have an issue with slugs crawling through my window at night. I find mucus trails over all sorts of surfaces in the morning, but I can't find the culprit(s). Where am I most likely to find them hiding during the day? Usually, slugs hide in moist, dark places to conserve body moisture, but I don't have any moisture in my room other than the barometric humidity. Are they going to feast on my paperwork or laundry, for lack of a suitable alternate food source? Plasmic Physics (talk) 00:56, 12 November 2014 (UTC)

You say they're crawling through your window, so wouldn't they be outside during the day? They can get through very small gaps. Do you have houseplants in your room? They may be coming in to feed on leaves and moisture dropping from the plants. Putting moistened slug pellets on your window sill should stop them.--Shantavira|^{feed me} 08:18, 12 November 2014 (UTC)

I'm more interested in the slugs which are already inside, as opposed to the ones who have yet to crawl in. I don't keep plants in my room. Plasmic Physics (talk) 08:45, 12 November 2014 (UTC)

Slugs like plants. They'll eat wet and rotting paper, but I don't think you need to worry about the crunchy stuff. Almost certainly not clothes. Even if they're starving, they just aren't built for it. They will slime them, of course. If they can get back out your window, they probably will. If not, check the corners. There are many kinds of slugs, though. And snails, which are also slimy. Maybe some have acquired a taste. InedibleHulk (talk) 09:30, November 12, 2014 (UTC)

How likely am I to be sharing a bed with one of them? I don't want to roll over right on top of one. Plasmic Physics (talk) 09:41, 12 November 2014 (UTC)

See window screen. The pores in one of those should be sufficiently small as to prevent slugs from making into your bedroom at night. --Jayron32 13:23, 12 November 2014 (UTC)

Also see apophallation. Better to share a bed with just one of them. If it's Limax maximus, don't worry; these things would rather hang above your bed on a slimeline to work on their night moves. Like a baby mobile (but different). InedibleHulk (talk) 14:12, November 12, 2014 (UTC)

Think that the OP's slugs are just looking for pastures new. Since his home is in the way, they explorer it too. As a kid, I loved making slug traps (they also provided tasty nibbles for my vivariums). There is much advice on google such as this. Example:[[21]]. Reduce the local population and the lower peer pressure negates them from being forced to explore ones home. The other thing I found, is that if one burns off the varnish from fine copper wire ( which I salvaged from army surplus headphone coils) and laid those out, the slugs and snail did not like to cross them. Gastropoda such as theses can metabolise many plant toxins, but in the 1960's we could just paint on a little dilute DDT over the glass-house threshold, non could not cope with that. Anti-seize-lubricant was also good as it too contains copper. Gastropoda know if the local population is too high and so emigrate – in this case into the OP's home. Houses are not their natural environment. Just reduce the local population with slug traps.--Aspro (talk) 14:52, 12 November 2014 (UTC)

Laundry detergent as dish soap

If someone uses powdered laundry detergent to do the dishes, is it safe? Anna Frodesiak (talk) 05:22, 12 November 2014 (UTC)

(EC)Make sure you rinse off the excess soap. Soap is not that toxic, otherwise soap packets would have warnings on them. But what do you think people used before dish-washing detergent? Graeme Bartlett (talk) 05:29, 12 November 2014 (UTC)

Not toxic, okay. Before dish-washing detergent? I never thought about. Bar soap? Some sort of plant? Anna Frodesiak (talk) 07:49, 12 November 2014 (UTC)

Sodium carbonate was cheap and commonly used. Laundry detergent is different from soap, by the way. I wouldn't use any scented product to wash dishes, but I'm fussy about residual scents. I guess it's OK if you rinse it off. Dbfirs 08:10, 12 November 2014 (UTC)

Sodium carbonate, eh. I'd never heard of that. Anna Frodesiak (talk) 21:42, 12 November 2014 (UTC)

It might be toxic. For example it contains Optical brighteners and other things. But then again dishwashing machine powder is also toxic, and they use that all the time. It's really all about rinsing it off thoroughly afterward. Ariel. (talk) 10:16, 12 November 2014 (UTC)

Fair enough. Thank you, all. :) Anna Frodesiak (talk) 21:42, 12 November 2014 (UTC)

Handlevwith care. I find the dishes to be much more slippery. Jim.henderson (talk) 23:20, 12 November 2014 (UTC)

petroleum engineers in USA

How many petroleum engineers USA want in 2030?

I learnt there's a growing demand for natural gas and oil

The United States Department of Labor projects about 48,000 petroleum engineers will be employed nationwide in 2022. Petroleum engineering employment is growing faster than the national average for other occupations, and demand is projected to continue growing "much faster" than the average. Do you specifically need predictions for 2030? Nimur (talk) 06:31, 12 November 2014 (UTC)

2030 is a very long way ahead for this kind of prediction. Will robotics and automation reduce the need to nearly zero? Will the demands of the industry mean that they need a ton of computer geeks but hardly any petroleum experts? Will the world finally come to it's senses about global climate change and drastically cut back on the demand for oil, and decimate the industry? Will the demand for oil continue to increase and require increasingly clever techniques to extract it from ever more difficult sources - pushing the demand for new engineering techniques through the roof? Will new oil discoveries in (...picking a place at random...) Outer Mongolia swamp the market with cheap Mongolian oil - driving the US industry into bankruptcy? We really can't answer any of those questions...nobody can. So we can't possibly come up with a good prediction...it's a wild assed guess at this point.

In the news right now, today, Saudi Arabia is deliberately selling its' oil at rock-bottom prices in an attempt to drive US domestic production out of profitability and into a death spiral. Will they succeed? Clearly they think so - and clearly the US industry doesn't think so or they'd shut down their operations right now and cut their losses. If those two sets of undoubted experts are dualling for such insanely high stakes rewards - then we know that they don't agree on what the outcome will be. If those experts don't agree on what the future of the US oil industry is...what chance do we stand?

SteveBaker (talk) 14:57, 12 November 2014 (UTC)

Steve, you make excellent points across the board. But, to be fair, the Department of Labor projections are a little better than a wild-assed guess. You can read about their projection methodology, which does specifically take into account the uncertainties that are inherent to each industry. The Department of Labor can arguably make the case that its projection is intended to be accurate - neither optimistic nor pessimistic - unlike the projections of a corporation involved in that industry. As a government agency, their projections do not positively affect their own profit-and-loss outlook or shareholder valuation. They employ statisticians and industry experts. There is a plausible case that they do have some biases that are difficult to overcome; but their role is to inform policy. If realistic evaluation of uncertainty implies that employment numbers for some specific American industry are on the verge of a catastrophic collapse, the Department of Labor wants to inform policy-makers and citizens about that issue. (As an excellent example, look at the textile industry, for which DoL projects a nearly 50% reduction in current employment over the next ten years. America's textile industry has shrunk for reasons too numerous to mention, but overseas competition is a very real contributing factor).

The petroleum in particular has a tendency to be very volatile, prone to sharp changes because of technology, politics, and outside economic factors. But even if E&P moves out of the United States, it is very probable that American petroleum engineers will continue to be very highly employable, inside and outside our borders.

Nimur (talk) 17:19, 12 November 2014 (UTC)

To add: Here is BLS's evaluation of its own 10 year projections made in 1996 (for year 2006). My takeaway:

• As Nimur says, the BLS projections are likely to be close to the best that can be done, and are certainly better than a seat of the pant approach, naive extrapolation, or just throwing up ones hands at the problem.
• As Steve says, one should be aware that the error bars on the projections can be pretty large, especially for jobs employing a small number of people (like the petroleum industry).

Abecedare (talk) 00:33, 13 November 2014 (UTC)

Transitional dipole moment

How do I find the transitional dipole moment of a particular carbon atom within a PAH according to the zero-overlap approximation. All I have, are the normalised SALCs, and the relative atomic positions. I'm trying to interpret equation 17 in the article [22]. Plasmic Physics (talk) 09:33, 12 November 2014 (UTC)

What is the relationship between lambda/nu and l/m, where l/m refer to the carbon atoms that define bond R_k? Plasmic Physics (talk) 09:54, 12 November 2014 (UTC)

Schiehallion experiment — determining mountain density

The accuracy of the Schiehallion experiment is dependent on a good estimation of the density of the mountain Schiehallion. The article doesn't state how this was determined. According to http://www.sillittopages.co.uk/schie/schie90.html, Hutton assumed that the exposed rocky outcrops were representative of Schiehallion as a whole. Is this what he did? CS Miller (talk) 11:37, 12 November 2014 (UTC)

CS Miller: Nothing quite as sophisticated as that. Here you have Hutton's own explanation. He assumed the mountain to be a mass of solid rock, and thus judged the density to be the same as "common ſtone". הסרפד (call me Hasirpad) 20:00, 12 November 2014 (UTC)

BTW That's not a typo of "ftone", that a Long s. Ariel. (talk) 00:03, 13 November 2014 (UTC)

<sings> ♪♫ "Where the bee ſucks, there ſuck I..." ♫♪♫ --Shirt58 (talk) 07:55, 13 November 2014 (UTC)

Philae (spacecraft)

Are the signals between the Philae probe and our planet (Earth) traveling at the speed of light? Bus stop (talk) 18:13, 12 November 2014 (UTC)

Strictly speaking the signals from Philae do not travel to Earth - Rosetta is used as a relay to reduce the power needed aboard the lander. Ignoring the minor delay in relaying, yes - radio waves are a type of electromagnetic radiation and like all other electromagnetic waves, they travel at the speed of light. WegianWarrior (talk) 18:51, 12 November 2014 (UTC)

Great, thank you for that. Does the signal take almost 1/2 hour to traverse the distance one way between Rosetta and Earth? Bus stop (talk) 18:59, 12 November 2014 (UTC)

It is 0.471 light-hours from Earth, so the transit time is 28.26 minutes. CS Miller (talk) 19:11, 12 November 2014 (UTC)

Great, thank you very much for that information. Bus stop (talk) 19:31, 12 November 2014 (UTC)

Of course, both time and distance are currently shrinking as the comet heads in towards the earth's orbit...so these numbers will gradually become smaller, then larger again. SteveBaker (talk) 15:12, 13 November 2014 (UTC)

November 13

Mitochondrial DNA questions

1. Please, in the least number of words and in the simplest way you can - Except for ATP production, what is the other main function of the Mitochondria?
2. What is the prevalence, in general, of known\defined Mictochondrial disorders? - What is the Ratio of Disorder\Births?

I guarantee these are not homework questions; Thank you, Ben. Ben-Natan (talk) 03:03, 13 November 2014 (UTC)

There are many different functions, really - biological structures and genes don't actually "know" what they are "for". The article mitochondria does list quite a few of them. If I were going to answer I might have talked about apoptosis, but the article seems to prefer uncoupled energy production (as per heat generation in brown fat) as the more important second function, and I can't really argue it.

The article mitochondrial disorders actually does list those stats currently, and cites its sources - 1 in 4000 births, but only about 15% of the diseases due to mitochondrial DNA proper. I haven't looked at such stats in a long time, but they sound plausible enough. Wnt (talk) 04:04, 13 November 2014 (UTC)

1. I never said or even clued that "Biological structures and genes know what they are for". I asked the question because I once read at a discussion here that Mitochondria have to main functions, 1 is ATP production and the other - well, that wasn't very clear from the text...

2. I couldn't understand what you meant at "about 15% of the diseases due to mitochondrial DNA proper"; did you mean that 0.0000375 births (15%/4000) are Mitochondrial proper? Ben-Natan (talk) 05:07, 13 November 2014 (UTC)

Question About the Reversibility of Gene Therapy

I apologize for my ignorance in regards to this, but is gene therapy theoretically always (fully) reversible or not? Futurist110 (talk) 03:46, 13 November 2014 (UTC)

As practically implemented, gene therapy is almost never truly reversible; it generally involves inserting bits of DNA into the cell; in theory this may be in a specific location (see adeno-associated virus), but in practice (as the deaths from leukemia attest) it can be less predictable. A clever approach might tend to pop out the preceding alteration, or be targeted to disrupt something that was added, but with varying degrees of success. It is however possible to make gene therapy that is designed from the beginning to be capable of being shut off; a laboratory mechanism in mouse studies involves using tetracycline to control transcription of an added gene. In theory such control mechanisms could be arbitrarily elaborate and sophisticated. In practice, it is still far too rare to see gene therapy even attempted in even the most straightforward situations where it should help. Wnt (talk) 04:11, 13 November 2014 (UTC)

Don't apologize for that!

At present gene therapy is not permanent, when the modified cells die the new ones don't have the therapy. So in a way it's reversible. However there is no direct way to reverse the effects, if you wanted to do that you would essentially need more Gene Therapy. So it's also not reversible. Ariel. (talk) 08:24, 13 November 2014 (UTC)

The Lactose has a sweet taste

Maybe that's what gives the sweet taste to the milk. Am I right? and does it raise the glucose in the blood - generally? (not for a medical advice, but to the facts about Lactose) 5.28.177.33 (talk) 06:14, 13 November 2014 (UTC)

Yes, and slightly old milk is sweeter since the lactose gets hydrolysed into smaller sugars, which are sweeter. Yes, it does raise glucose since it has glucose in it, but not very much. Ariel. (talk) 08:27, 13 November 2014 (UTC)

Thank you 5.28.177.33 (talk) 12:11, 13 November 2014 (UTC)

Thermodynamics properties of chemical substances

If the chemical and physical properties of the chemical substances are always dependent on their valence and their molecular structure of the chemical substance, so that did the thermodynamic properties of the chemical substances to been defined by valence of this chemical substances?

Valence of what chemical substances is always been much, the valence of the carbonaceous gases or valence of the alkalic vapour and acid vapour (chemical vapours)?--Alex Sazonov (talk) 09:59, 13 November 2014 (UTC)

It is unclear what you mean by valence? Valence is a property of an element in a chemical compound that refers to the number of electrons that participate in chemical bonding. The way you are using the word here does not make sense. Perhaps you mean something different than what you are asking, but you have such a poor use of the English language it is hard to follow your questions. It may be best for you if you asked questions at a website where the other users spoke your native language. --Jayron32 11:35, 13 November 2014 (UTC)

Gases and valence

What natural gases in natural nature always had a lot, the natural gases which had a much valence or natural gases which had a small valence?--Alex Sazonov (talk) 11:16, 13 November 2014 (UTC)

What do you mean by natural gases? Also, your use of English is so idiosyncratic that it makes it difficult for people to understand you well enough to know how to answer your questions. You should consider finding a website in your native language to answer these questions instead. --Jayron32 11:35, 13 November 2014 (UTC)

As the world industrial history always told, that at first was developed a mineral raw sources which had a low cost of raw material production, as well as had a natural raw sources material which had a low cost of industrial processing, so that I believe that natural gases which had a much valence was developed in the first place!--Alex Sazonov (talk) 15:52, 13 November 2014 (UTC)

cushing's syndrome

A person suffering from Cushing’s syndrome will have symptoms that include rapid weight gain, particularly of the trunk and face (moon face) with sparing of the limbs. Why & how does the syndrome affect the body in this way? b.Could the consumption of hydrocortisone of 20mg daily to alleviate adrenal insufficiency also cause a “moon face” effect?

Looking for further reading on cosmic body physics particularly comets/soft bodies type and collisions

First is the bit I understand and what made me curious.

Was looking at [23], which shows the Lutetia big side up and marks the circles of their craters.

And then this one [24], which gives a sort of impression of two comets that collided and did not quite make escape velocity. So, I was think about the gravity and friction of when two bodies collide. Obviously the two had collided and caused a temporarily plastic surface, like, or even as, a wet blob, and eventually friction and other stuff brings it to a halt as the new single body.

However... Would the internal friction alone be enough to bring the surface to a settling halt? I assume the external tidal forces, such as the pull of the sun, would be the cause of the surface in the absence of any absorber of the collision force. Can anyone say a subject with particular focus on cosmology that will tell me stuff like if stuff outside the suns area of effect actually settles into a constant steady surface some time after impact, as the Lutetias is, and stuff about how that settling actually works out there?

I searched up stuff like collisions and gravity but of course it's a very specific item. There's probably not an article in it but aren't half of us wondering about comets and that today?  :)~ R.T.G 15:32, 13 November 2014 (UTC)

The escape velocity of 67P/Churyumov–Gerasimenko is 1 m/s, less than walking speed. If it formed through two bodies colliding, it was an incredibly minor crash. Rmhermen (talk) 15:52, 13 November 2014 (UTC)

And it would also take a very long time for the two to approach each other at those speeds, maybe thousands of years ? StuRat (talk) 16:36, 13 November 2014 (UTC)

I think you're looking for information about hydrostatic equilibrium.

On Earth, we use hydrostatic equilibrium to describe, say, water in a pipe; or oil-and-vinegar that have separated out into layers based on their different densities.

In planetary science, we can use the models and terminology of fluid dynamics to study all matter. Everything is a fluid on a sufficiently long time-scale!

One of the current elements in the definition of a planet is that the object's matter has enough self gravitation to achieve hydrostatic equilibrium. That means two things: there's enough material - and it's made of chemicals that are soft enough relative to its own mass - to squish into a spherical object. This process can take thousands, millions, billions of years.

Comets are made of water and carbon dioxide ice, among others (methane and ammonia for some comets). They sometimes also contain a lot of other harder materials: to use the terminology of comet scientists, there are also "metallic" and "chondritic" (rock-like) chemicals. Depending on which theory applies to any specific comets, those chemical compounds are primitive - they evolved directly out of stellar nucleosynthesis products - so they have never been subject to processes of geological evolution. That means that the iron in a meteoroid or a comet was never "refined" by heat and pressure; the "rock" and "dust" have never been subjected to the usual earth-style "igneous rock"/"metamorphic rock" progression; and although exposed to the harsh environments of space, there's not a whole lot of physical erosion action. These materials are kind of strange! Over a long time - billions of years - the materials have been subjected to direct, unfiltered stellar radiation, and extremes of temperature and heat. This actually can chemically change some of their materials. Over billions of years, exposure to sunlight has an erosive effect, softening "rock" and turning it into dust! (Solar Wind and Micrometeorite Effects in the Lunar Regolith, (1977).

Add on top of this that the comet's elliptic orbit cycles it through a variety of solar distances, ranging across several AU. Methane and ammonia and water and carbon dioxide - all of which might be gravitationally bound to the comet - can turn from liquid, to solid, to gas, depending on the effective planetary temperature of the comet. So, one day the comet might be a bunch of sand and gravel that's glued together by rigid ice - and the next, it might be a swampy clump of wet sand and metal fragments! When that happens, the material can re-shape.

Last, but not least, there is a stronger force than gravity: electrostatics. The comet, and all of its gas and solid components, are blasted by highly energetic solar wind. Some of the atoms become ionized. When this happens, the material in the planet is subject to electrostatic attraction - or repulsion - and the strength of these forces can be orders of magnitude larger than the attractive force of gravity.

If there is enough matter, gravity will win: the self-gravitation of all these particles will, over the long run, cause the materials to smush together into a nearly perfect sphere. For a comet the size of Comet 67P/Churyumov–Gerasimenko, this hasn't happened yet - and very likely won't happen for a very very long time, comparable to the lifetime of the solar system. It will always be irregular!

Let me close with a pitch for one of my favorite books on planetary formation - one that doesn't pull any punches or leave out any equations! de Pater and Lissauer, Planetary Sciences, which has an entire chapter on comets and meteoroids; and another entire chapter on planetary models of hydrostatic equilibrium!

Nimur (talk) 16:42, 13 November 2014 (UTC)