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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

Gases and valence

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? — Preceding unsigned comment added by 113.210.35.128 (talk • contribs) 14:24, 13 November 2014 (UTC)

Sensitivity to hydrocortisone, which is what we call medically-administered cortisol, varies greatly from person to person (so it's not possible to give an accurate, simple answer to your question - the effects are too variable). The differential sensitivity of various types of adipose tissue (visceral and peripheral, among others - see some listed in that linked article) to the opposing effects of cortisol vs. elevated insulin levels that cortisol can stimulate, probably determines the pattern of fat redistribution. -- Scray (talk) 20:06, 13 November 2014 (UTC)

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 , which shows the Lutetia big side up and marks the circles of their craters.

And then this one , 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 - it was written by the scientists who worked on the extrasolar planetary mission of the Kepler Space Telescope - and it 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)

Brilliant by User:Nimur. ~ R.T.G 00:00, 14 November 2014 (UTC)

What is the farthest you can communicate with an unlicensed (and legal) radio?

--Senteni (talk) 17:18, 13 November 2014 (UTC)

According to whose laws? --Jayron32 17:20, 13 November 2014 (UTC)

Well, US, Europe, although I suppose there must be an international aggreement on this, so all countries will let the same wavelength free.--Senteni (talk) 17:35, 13 November 2014 (UTC)

For starters, see Amateur radio, International_Amateur_Radio_Union, and pirate radio. maybe DXing has some interest as well. SemanticMantis (talk) 17:42, 13 November 2014 (UTC)

Note that it's not just a matter of what wavelength. Maximum transmission power, antenna size and other factors will be dependent on local laws. Also as those articles illustrate, it will depend on time of day and other factors. Additionally, "unlicensed and legal radio" is unclear. AFAIK, in many countries amateur radio operators can operate in frequencies and possibly with greater power without a specific licence for the radio, but they do need a licence themselves. Nil Einne (talk) 18:04, 13 November 2014 (UTC)

For the purposes of this question... does the radio signal need to propagate wirelessly? Nimur (talk) 19:19, 13 November 2014 (UTC)

I think I know what you're getting at, but radio says "Radio is the radiation (wireless transmission) of electromagnetic signals through the atmosphere or free space." (emphasis mine) - Do you really commonly refer to signals sent through a wire as "radio signals"? SemanticMantis (talk) 19:33, 13 November 2014 (UTC)

Actually I was thinking of a similar thing. Namely whether the OP was truly restricing the question to parts of the EM spectrum generally considered radio which includes some stuff also sometimes considered microwave and other things, but generally never stuff called light. Because high powered laser laws are still often limited albeit increasingly getting more stringent thanks to pressure from idiots misusing such lasers (and even then, some countries restrict readymade laser devices much more heavily than the diodes). Of course this illustrates another point, you can theoretically communicate quite far with lasers depending I think on atmospheric conditions and other factors. Possibly further than with an unlicenced radio even one designed to send to space (although I'm not sure). However there's no one to actually receive your line of sight signal somewhere in outerspace. Nil Einne (talk) 13:44, 14 November 2014 (UTC)

If you are talking 2-way Line-of-sight radio the Marine VHF radio article mentions some ranges. I do not see refs to support all the info though. I would imagine radios at sea would be more consistent in performance since there is no unpredictable terrain. It mentions 111 km with 25 watt transmitter. I went through some ads for handheld high powered 2-way radios and they went up to 5 watts. Richard-of-Earth (talk) 19:36, 13 November 2014 (UTC)

Looking around some more that article has to be wrong. This mentions line of sight on a curved earth max range is 13.3 miles (21.4 km). Richard-of-Earth (talk)

I think the article might still be right. The marine VHF article says ~100 km for tall ships or antennae mounted on hills. Your recent link says 13 miles for a 100 ft antenna. Surely large commercial vessels will have much higher antennae, and consequently longer range, as described by the equations at line-of-sight propagation. (I did not check all the math, just saying that the two pieces of info are not necessarily contradictory) SemanticMantis (talk) 20:04, 13 November 2014 (UTC)

Larger ships that travel far from land will also have access to HF radio (which is not limited to line of sight), or ultra-high-frequency radio (or microwave radio) satellite uplink (which is line-of-sight to an orbital digital radio repeater). Nimur (talk) 20:07, 13 November 2014 (UTC)

Hmm. The OP really does need to give more specifics. this article mentions the different types of radios, their ranges and needs for licenses (in the US I am sure). If you are transmitting for an aircraft, up to 200 miles! So you have to buy or charter a plane too. Of course, you can walk into a store, buy a disposal cell phone and communicate via radio to anywhere on planet, no licence needed. Richard-of-Earth (talk) 20:31, 13 November 2014 (UTC)

In many countries, the mobile phone or its transceivers will however need to be appropriately licenced. (At the very least, in most cases the spectrum they are operating can only be used because whoever's network your connecting to paid the government good money to be allowed to use said spectrum. And said operator usually sets standards which you are required to follow, failing which they may ask you to stop using their network or even take legal action against you.) Nil Einne (talk) 13:28, 14 November 2014 (UTC)

Technically you can communicate around the world, just use a low frequency. Looks like below 9khz is unlicensed (not certain though). But your bandwidth will be tiny. Some links to check: ELF SLF ULF VLF Ariel. (talk) 20:40, 13 November 2014 (UTC)

Technically, it is prohibitively difficult for an amateur on a limited budget to broadcast a strong signal at VLF or lower frequency. A quarter-wave antenna at 30 kHz would be 2.5 kilometers high. VLF and lower frequency transmitters tend to be operated by scientific researchers and by well-funded governments. Nimur (talk) 00:17, 14 November 2014 (UTC)

???? The OP is asking about unlicensed but legal transmitters. Hams (with legal licensed transmitters) have been doing EME (that's about all most half a million miles) since about the 1960 and all without a government grant of billions of dollars. For lower frequencies, a British and New Zeeland ham duo were able to communicate at 2 (two) watts, by careful frequency and phase matching and signal period. A technique, later adopted many decades later by JPL in order to pull in the very weak 20 watt transmissions from Voyager one & two (and they added a bit of computerized statistical analysis as well, to speed things up, and to help filter out the signal from the background noise). Most unlicensed but legal transmitters are in the upper frequency range so don't travel much further than the visible horizon during time of normal propagation. During time of tunnelling however, US police VHF communications have been hear in the UK. I have also received VHF from a guy whilst walking his dog on the shores of Holland who had only a 5 Watt transceiver but due to atmospheric tunneling he came in loud and clear. Sea water (being conductive) can create a dielectric wave guide taking the signal way beyond the radio horizon. So lets not hear any more of this “Technically, it is prohibitively difficult for an amateur on a limited budget“ nonsense. --Aspro (talk) 14:37, 14 November 2014 (UTC)

Most HAMs aren't transmitting below 50 kHz - ergo, "VLF", "ELF", and so on. "VHF" and "VLF" are one letter and many hundreds of thousands of dollars of equipment apart. Nimur (talk) 16:04, 14 November 2014 (UTC)

Most HAMs may not be transmitting below 50 kHz but some do and quite successfully without billion dollar grants. But this is with legal licensed equipment. Most no-licensed-required legal equipment (as asked by the OP) uses VHF and above.--Aspro (talk) 16:29, 14 November 2014 (UTC)

I have no doubt that some amateur radio enthusiasts may try to transmit VLF; but they probably fail to generate very strong signals. This is what a VLF transmitter looks like: NAA as viewed from two miles away. That is not a grouping of several dozen different VLF aerials: all of those towers are the radiating elements for one single VLF transmitter. The wavelength of the center-frequency is about eight miles. So, if you wanted to build a crappy, inefficient, barely functional amateur-grade whip antenna (instead of one of these sophisticated multi-element radiator arrays that the Navy uses), you'd still need a piece of wire five miles long, and you'd need to somehow attach it to a tower that would be taller than the tallest structure ever built by humans. At wholesale prices, the wire-runs alone would cost upwards of $60,000, but the engineering and construction costs would be ... a little more complicated to estimate! That's at 24 kHz. Lower frequency radio, like ELF, corresponds to even longer wavelengths.

In March 2014, HAM operator W2ZM claimed to transmit trans-Atlantic signal at 29.499kHz on WH2XBA. I would go so far as to say, this level of equipment is non-amateur. In fact, it is actually regulated as radio licensed for scientific research.

Let me re-iterate: I have no doubt that some amateur radio enthusiasts may try to transmit VLF; but they probably fail to generate very strong signal that would be suitable for long-distance propagation. It is much much much more efficient for a HAM to use an HF transmitter and use the skywave effect to transmit over the horizon. Nimur (talk) 18:36, 14 November 2014 (UTC)

Oh Boy! Allow me re-iterate. The OP is asking about Legal but unlicensed' apparatus. What has power got to do with it? See Shannon–Hartley theorem. The VLF image you referred to, is that high, because it is more efficient than it would be lower down, but a lower antenna is still going to radiate. Have you heard of antenna that are λ/2, λ/4, λ/8 high and in length etc. Right. So why oh why, does one need five miles of very expensive sleeved cable cable costing $60,000 like you linked to? It is up in the air -it does not need to be copper or have any insulation (use plain aluminum) and just a mile will do. $500,000 dollar towers ? Answer: String the antenna from tree to tree. If one has to have all ones teeth veneered by a dentist because one drank too much coke and soda pop as a child, then in comparison, the cost of an amateur VLF antenna and associated equipment is hardly astronomical- is it? -Finally, the OP asks about Legal frequency but unlicensed. Most frequencies above 9 kHz have been allocated by the ITU. So in answer to the OP's question its about 3800 miles in normal day/night conditions with current practices; unless one is doing EME work but one will probable require a license for that in many countries as the side lobes could cause interferance. See and I quote:McIntyre needed no FCC license to transmit on 8.971 kHz, since the Commission has not designated any allocations below 9 kHz.--Aspro (talk) 21:25, 15 November 2014 (UTC)

PS. Do you know what a whip aerial is and why they are used, together with their efficiency and suitability in the right application? You say “barely functional amateur-grade”? Look at the specs and compare them to commercial (cheap (?) and cheerful) whips that cost an arm and a leg. Then see if you can find the fallacies you're using from this List of fallacies. Just asking (;¬)--Aspro (talk) 21:59, 15 November 2014 (UTC)

The article you really need to read is Tropospheric propagation and the short answer is several thousand miles under ideal conditions. For the purposes of this post I am assuming the OP is referring to unlicensed UHF hand-held transceivers that operate near 460 MHz in most countries (where they are legal). Roger (Dodger67) (talk) 14:16, 14 November 2014 (UTC)

There are also some frequencies that have unlimited radiation regulations. 13.56MHz used to be a frequency that was chosen for certain equipment because it wasn't regulated. --DHeyward (talk) 00:05, 15 November 2014 (UTC)

Why are we able to see light from almost the time of the big bang, should it not have got passed us?

I know that the further away an object is, the further back in time you're looking at that object, it's simply because light takes time to reach us, and as a result we are able to see objects that are over 10 billions years now, to almost to the time of the big bang itself. The question I have is how come we are able to see that light given that everything started from a single point and that everything escaped from that point, and given that light goes faster than us, us made of matter, that light should have passed us almost right from the beginning and should now be impossible to see, so my question is why are we able to see light that came from almost the time of the big bang given that that light should be out of reach? Joc (talk) 19:55, 13 November 2014 (UTC)

That is because space is glowing like a cooling ember. We cannot see the fire before the ember though. Plasmic Physics (talk) 20:21, 13 November 2014 (UTC)

That doesn't really answer the question. Vacuum or space can not radiate light (even if you had the energy, where would the momentum go?). So what is glowing? Ariel. (talk) 21:44, 13 November 2014 (UTC)

You are taking my metaphor too literally, I mean that even though it's not the honest truth, space itself may as well be glowing. The CMB was caused by the gas in the early universe cooling down. However, the rate of expansion out-paced the speed of light, and so the light from the glow is delayed. It is effect as hearing a lightning strike sometime after the matter, due to the difference between the speed of light, and speed of sound. Plasmic Physics (talk) 01:04, 14 November 2014 (UTC)

First, it's not accurate that everything escaped from a point. A better analogy is that of an expanding balloon, with two dimensional creatures living on the surface of the balloon. To the 2D creatures, there is no third dimension. Their universe is expanding, but there's no point in space that everything is escaping from.

We can see almost to the Big Bang because at that time, we were moving nearly at the speed of light relative to the point we now see. The speed of light was so close to the speed of expansion that light only managed to catch up after 14 billion years. --Bowlhover (talk) 21:55, 13 November 2014 (UTC)

See Inflation (cosmology) for why light got left behind. Dbfirs 23:21, 13 November 2014 (UTC)

No, inflation is not really it. The balloon analogy is better. Imagine a constantly growing balloon (ok, there is some inflation ;-). We are living on and looking along the surface of the balloon in this reduced dimension. But no matter how far you look, there is always a piece of the balloon that is that far away, and from which light has travelled for a corresponding amount of time. --Stephan Schulz (talk) 00:04, 14 November 2014 (UTC)

OK, point taken. Also, inflation happened before photons of light came to exist, and long before there were stars to shine, so the balloon started partially inflated. Perhaps a constantly stretching flat rubber sheet would be a better analogy if you believe that space is flattish. Dbfirs 00:27, 14 November 2014 (UTC)

Bowlhover: I agree that matter was going at almost the speed of light at the moment of the big bang but now we are going much slower, it seems to me that the light from the big bang should have passed us long ago.

Plasmic Physics: I agree that the CMB (Cosmic Microwave Background) is like the amber of the "explosion", an ambient light all around us that came from the big bang, but unless I'm mistaken, what we are actually seeing are very old galaxies that existed almost at the beginning of the universe, and again, how come we can see them, how come the light has not passed us and make them impossible to see???

Stephan Schulz: the balloon analogy seems to best answer to my question; both me and the far away galaxy are moving apart, that means that light has a longer distance to travel, which allows me to see further in the past. It seems like a race condition, the speed of the expansion of the universe against the speed of light. Would be nice to get details on that. Joc (talk) 22:14, 14 November 2014 (UTC)

See Metric expansion of space for details of the race. The expansion is currently accelerating. My point was that space had a head start. Matter as we know it (three states of atoms) didn't exist immediately after the Big Bang. Dbfirs 22:28, 14 November 2014 (UTC)

Joc, the thing to understand is that the Big Bang didn't happen at a place. From our perspective, it happened at all places. All of space originated from the Big Bang, and consequently, all of space was filled with hot plasma in the initial moments after the Big Bang. In essence, when we look deep into space in one direction and see the cosmic microwave background, we are seeing what the after effects of the Big Bang looked like in that particular location a long time ago, and when we look in a different direction, we are seeing the after effects of the Big Bang somewhere else a long time ago. The Big Bang affected all of space, so if you look a great enough distance in any direction, you'll eventually see light that originated from the era shortly after the Big Bang itself. And the light you'll see reflects the impact of the Big Bang on that specific region of space far, far away (it's nearly the same in all direction, but people who study the cosmic microwave background can gain big insights from small difference depending on where you look in space). Also, the cosmic microwave background was created by the glow of recombination (cosmology), a side-effect of the universe cooling after the Big Bang and forming the first atoms (instead of ionized plasma). It predates the formation of galaxies and stars. Dragons flight (talk) 23:07, 14 November 2014 (UTC)

That it happen in "all places" implies that the universe is infinite, that also implies that light has an infinite amount of space to travel, and so it implies that we could look an infinite amount of time in the past, even before the big bang! Now I know that's wrong, but I don't know how it's wrong. I'm NOT interested by the CMB, what we measure is it's temperature and it glows everywhere; what I'm interested is that I read that we can actually see galaxies from very near the time of the big bang, and that we can see them clearly enough to be able to tell they they are "primitive", that they didn't have the time to form structures such as spirals for example, this is not the diffuse light of the CMB but light from a very precise point in space and time, the thing I don't understand is how those photons didn't get passed us since they are faster than us, given that everything came from the same point (if everything is moving away, reversing the time arrow, implies that everything came from the same point).

The universe may be infinite, or it may simply be far, far bigger than the part of it that we can see. Either theory is consistent with cosmology and the shape of the universe as we know it. The expansion of the universe makes many things confusing, but lets ignore that for a moment. Ignoring expansion, we would assume that the oldest galaxies formed ~13 billion years ago, in a region of space ~13 billion light years away, using matter and energy the Big Bang left in their local region of space. As far as we can see, the Big Bang left a nearly uniform density of matter everywhere, and it did so as far back in time as we can see. In practical terms, that's what it means that the Big Bang affected all of space, it deposited nearly uniform matter everywhere we can see at the very beginning. That may continue literally forever (an infinite universe), or it may stop somewhere beyond the visible universe that we can see, but either way all of space for as far away as one can choose to look, is filled with matter. Incidentally, the CMB is the limit of how far one can look. At that point you are seeing the glow of the Big Bang, and no light older than the CMB survived.

For a slightly more nuanced description, that includes expansion, one would say that the earliest galaxies formed ~13 billion years ago in a region of space that is now ~40 billion light years away. The extra ~30 billion light years is associated with the expansion of space, but the light only traveled ~13 billion years to reach us because at the time it departed the two regions of space were much closer. Even accounting for expansion though, the far away region of space 13 billion years ago already had a similar density of matter as the region of space we presently live in had 13 billion years ago. The Big Bang deposited matter everywhere we can see during the very earliest moments of time (e.g. inflation), well before those early galaxies formed.

To return to the balloon analogy, the universe is like the surface of a balloon, and the density of matter can be thought of as like the thickness of the rubber. As the balloon expands, all points get farther away from one another and the local density of matter (i.e. rubber) decreases. The universe stretches and thins. However, the balloon always had rubber everywhere, it was created that way. No matter how you shrink or expand the balloon, there is no point in time where the rubber vanishes, it simply becomes more or less dense. On cosmological scales, the matter in the universe is the same way. The instant of the Big Bang created the universe (i.e. the balloon) with matter everywhere. The matter was then stretched and expanded, becoming less dense, but there was no region of space (as far as we can see) that ever lacked for matter. Dragons flight (talk) 20:23, 16 November 2014 (UTC)

A slight improvement on the balloon analogy would have galaxies stuck onto the expanding surface in a rigid material, so that only the rubber between the galaxies expands. Dbfirs 00:25, 18 November 2014 (UTC)

November 14

All the different dimensions

Do I understand correctly that we, you and I (and everything) are present in all the dimensions at once? Sometimes people talk about something coming from another dimension as though it came from a different universe whereas I have always thought of dimensions as being something we have a position in. Thus instead of coming from a different dimension, some object or creature might come from a different position within that dimension to our position in that dimension and thus become observable to us? Is that wrong? --78.148.109.47 (talk) 05:21, 14 November 2014 (UTC)

Yes, yes, no. Plasmic Physics (talk) 05:48, 14 November 2014 (UTC)

Is it so simple? Is time a dimension? Am I currently "present" at all points in time? Block universe and multiverse might be of interest when thinking about this question. SemanticMantis (talk) 16:51, 14 November 2014 (UTC)

Yes, time is normally considered a dimension, but behaves differently than the other dimensions, for reasons that cannot be explained in current physics. When something is said to have "come from a different dimension", it usually means that it is said to have come from a higher-order spatial dimension, presumably a spatial dimension with full extension that we cannot observe. The universe that we can observe consists of three spatial dimensions and time. Some Theories of Everything have various additional dimensions that are "rolled up". So if something really has come from a dimension beyond the three that we can observe, it is a matter of terminology or philosophy whether it comes from another universe or an aspect of this universe that we cannot observe. Robert McClenon (talk) 17:07, 14 November 2014 (UTC)

Yes, yes, no to your questions also. Plasmic Physics (talk) 03:55, 15 November 2014 (UTC)

"Yes, yes, no" to my questions? I wasn't asking questions. Does that mean yes, yes, and no to the OP's questions? Robert McClenon (talk) 22:32, 15 November 2014 (UTC)

No, the indent level indicates that I was responding to Mantis. Plasmic Physics (talk) 00:23, 17 November 2014 (UTC)

See Flatland.—Wavelength (talk) 17:24, 14 November 2014 (UTC)

Be aware that Flatland is primarily a social satire rather than a scientific textbook, although I can second Wavelength's recommendation. Tevildo (talk) 19:50, 14 November 2014 (UTC)

Yeah Flatland's coverage of 2D life is exceedingly patchy and inconsistent. I don't know why people still recommend it for that reason. A VASTLY better book about a 2D world is "Planiverse" - which is modern, has lots of clever insights and an actual, interesting plot. SteveBaker (talk) 21:19, 14 November 2014 (UTC)

I wonder if you are actually talking about quantum states, as in the Schrödinger's cat, for example an electron exist in several quantum states simultaneously, so is every particles in the universe, so we would be into an Multiverse, and to my knowledge it's not possible to go from one "universe" to another, a bit like it's impossible to have a coin with a single face, both sides exist or none exist. Joc (talk) 21:03, 14 November 2014 (UTC)

In theories with small compactified extra dimensions, ordinary matter spans the entirety of the extra dimensions—it's "fat" in the extra dimensions, if you like. Matter at much higher energies can be "thin" and have a position in the extra dimensions, but it will always be visible to ordinary matter because the ordinary matter is everywhere. In braneworld models, ordinary matter is stuck to a lower-dimensional surface (the brane), so it does have a position in the higher-dimensional space. However, I don't think there's any way for higher-dimensional objects not attached to a brane to exist in those models. There's nothing out there except gravity. The idea, common in fantasy/SF stories, that you could see a slice through a higher-dimensional object as it passed through our lower-dimensional world is not consistent with any physical theory I've heard of. -- BenRG (talk) 23:02, 15 November 2014 (UTC)

Designing experiment to compare thermal clothing performance

I was thinking of designing and performing an experiment at home to determine the performances of different items of thermal clothing and I was wondering if someone might care to contribute to ensure that I don't miss any opportunities and flaw my experiment.

I thought I could simulate the body with a hot water bottle, placing a temperature sensor on the bottle and putting the thermal clothing over the bottle. Then the drop of the temperature could be logged over time. I would also measure the temperature of the air in the room and weigh the item of clothing excluding the sleeves. I would perhaps repeat the experiment with an additional, unvarying layer (e.g. a thick jumper) and with a fan blowing on the bottle/clothing from a fixed angle and distance. I could use a computer fan with known manufacturer specifications to give an indication of the amount of air being moved. I suppose I would also need an accurate hygrometer to know how cooling the moving air would be?

Do I need other sensors? Should I redesign the experiment?

I want to produce a table that will allow me to determine which clothing offers the best weight to insulation ratio and the best cost to insulation ratio. I guess I'll need to record the dimensions of the garments since some will be more generous than others.

Are the thickness and permeativity to sweat worth consideration?78.148.109.47 (talk) 05:40, 14 November 2014 (UTC)

The thermal performance of some garments is likely to vary between them being worn, and simply draped over an object (e.g. thermal underwear is generally stretched when worn). MChesterMC (talk) 09:27, 14 November 2014 (UTC)

...which can be good or bad, as it may restrict heat loss by air circulation. At least in Germany, some major outdoor stores have cold chambers with infrared cameras where they allow you to try out your particular piece of clothing on your particular body, and look at the heat loss. Some also simulate wind in the chamber periodically. However, this is more a marketing gimmick (with windows for your friends to look in and make fun of you), and probably not suitable for exact measurements or large-scale comparisons. --Stephan Schulz (talk) 10:56, 14 November 2014 (UTC)

One point that hasn't been mentioned yet - you need a control for your experiment to have meaningful results. A hot-water bottle that's not wrapped in anything would be a possibility. Note also that the results will depend on the temperature (and humidity) of the room, which (presumably) isn't very precisely controlled, so you'll need to factor this in. A third point - weight is not the only important parameter when it comes to how comfortable clothing is, otherwise we'd all wear polystyrene clothing in winter... Tevildo (talk) 19:05, 14 November 2014 (UTC)

There is an important difference between a hot water bottle and the human body. We generate heat internally - so the temperature of a human wouldn't vary much over the duration of the experiment, although we might have to resort to shivering and such to keep the body at the right temperature throughout. But the hot water bottle will gradually cool off. So perhaps we could imagine some kind of garment that releases heat very easily at body temperature, but insulates more and more effectively as the temperature drops (or vice-versa). That garment would perform much better in the experiment than it would with a human subject. Now, I can't think of a material that would act like that - but the whole thing about an experiment is to find that out and not be tricked by things like that. SteveBaker (talk) 21:15, 14 November 2014 (UTC)

Then use an electric blanket. Changing out the three-position switch on most with a variable rheostat should allow you to generate a constant temperature. You wouldn't even need a blanket to get to 98.6; you'd merely need the surface of the blanket to be able to maintain skin temperature, which for most people is somewhat less than body temperature. Use an electric blanket, calibrate it to output constant skin temperature, and wrap it in various fabrics. Measure the rate at which the outside of the fabric heats up, and you'll know which fabrics are better at retaining heat and which release it faster. --Jayron32 03:05, 15 November 2014 (UTC)

• It seems to me that the technique will measure diffusive cooling pretty well but won't measure radiative cooling. I don't know how important that is on the whole -- it definitely comes into play in some situations. For example a person inside a tent at night will stay warmer than a person outside under a starless sky, even if the air temperature is the same and there is no wind, because the tent reflects radiation back. Looie496 (talk) 02:45, 15 November 2014 (UTC)

• Something that hasn't been mentioned is how you will secure the fabric to the hot water bottle, and how the assembly will be held in the test chamber. I would suggest you sew the fabric samples into identical "water bottle cozy" shapes, such that you can slip the water bottle in and out, with a hook sewn in so you can suspend the assembly. This will help to ensure identical test conditions, which you won't get by just draping fabric over the hot water bottle. StuRat (talk) 02:53, 15 November 2014 (UTC)

As a home setup that is simple and economical, what about having a glass with a fixed amount boiling water surrounded with insulation except at the top which would have the garment, being careful not to touch the water, and then after a fixed amount of time, measure the temperature and the weight of the water, that will give you a relative measurement of the thermal insulation and how well the garment can "breath". You could also touch the garment to see if it feels wet. If you repeat the experiment with the same setup every times and compare the data for each garment you should get a good idea of the relative merit of each garment. Obviously a much better test would be to have someone wear the garment and do a standardized workout and ask for their impression, that would be a much more thorough and more meaningful evaluation. Joc (talk) 18:50, 15 November 2014 (UTC)

Shear strength of soil

Does the size of aggregate in soil affect internal friction angle? My assumption is that finer aggregates are more likely to be rounded reducing it and also means there would be more weakness planes in between aggregates reducing cohesion. Am I correct? — Preceding unsigned comment added by 194.66.246.26 (talk • contribs) 09:00, 14 November 2014 (UTC)

I'm not sure what you mean by "aggregate" here, as this normally refers to a construction material of specially graded material rather than soil. As stated in the soil article: "Soil particles can be classified by their chemical composition (mineralogy) as well as their size. The particle size distribution of a soil, its texture, determines many of the properties of that soil, but the mineralogy of those particles can strongly modify those properties. The mineralogy of the finest soil particles, clay, is especially important." In other words, the type of material at least as important than the grain size. And you certainly can't assume that finer grains are more likely to be rounded.--Shantavira| 16:39, 14 November 2014 (UTC)

Yes, size of aggregate will affect shear strength, but I agree with the above that smaller particles are not necessarily more rounded. The word "aggregate" is indeed used in soil science (in the field of study, as well as our related articles). We have pretty good articles at soil structure and soil mechanics that discuss the effect of grain size and other features on soil properties. SemanticMantis (talk) 16:48, 14 November 2014 (UTC)

Why the DAF-2 gene is not extinct?

Hi there,
I've read about Daf-2, and I wonder why that gene has been surviving?
Exx8 (talk) 10:29, 14 November 2014 (UTC)

Because organisms who carry the gene don't die before they have a chance to pass it on to offspring. --Jayron32 10:40, 14 November 2014 (UTC)

Yes, and even if an allele does confer some disadvantage, it may remain in the population indefinitely if it also confers some benefit. In this case, DAF-2 seems to have a functional role in regulating reproductive development, and knocking it out may indeed prevent the organism from being able to reproduce at all. Also, the locus takes part in controlling formation of Dauer_larva, which seems to confer a large benefit for the overall population. Some academic papers on the topic here . SemanticMantis (talk) 16:42, 14 November 2014 (UTC)

Note also that even our article says "Disabling DAF-2 arrests development in the dauer stage which increases longevity, delays senescence and prevents reproductive maturity". Nil Einne (talk) 19:27, 14 November 2014 (UTC)

Uniqueness of Human Bones?

If presented with a *large* box containing one set of adult male bones each from the 7 species of Great Apes how many of the bones of the Human would be distinguishable from the others 1) by a layman, 2) by a Forensic Anthropologist without tools 3) by a Forensic Anthropologist with a full lab. I'm guessing #3 would be all, but for #1, I'm guessing a good number, but I'm not sure if #2 would be all (Free floating ribs and individual vertibrae for example, I guess would be tough. (Would adding any other animal beyond the great apes make things more complicated other than simply increasing the number of bones.Naraht (talk) 15:16, 14 November 2014 (UTC)

For #2, it's going to vary a great deal depending on the background of the individual. Primatology is often not part of the curriculum for, say, undergrad anthropology courses. It would be quite easy to get a doctorate in that field without any more than a passing knowledge of what chimp bones look like. The advantage they'd have over a layperson is their deep familiarity with human osteology. On the other hand, if their undergrad work or grad studies included courses in primatology and/or palaeoanthropology and/or comparative anatomy, then they'd be much better off. Even having a personal interest would greatly increase their ability. The answer for #1 would range from folks with almost literally no knowledge of what a skeleton looks like (I've seen an archaeology undergrad identify a squirrel pelvis as its skull) all the way to amateur bone hunters that could give the pros a run for the money. For #3, the biggest piece is probably not having a "full lab", but having a decent light and magnifying lens with a really good book. Matt Deres (talk) 16:09, 14 November 2014 (UTC)

If the bones are fresh enough, DNA analysis should be able to cluster them into disjoint sets easily enough with a good lab. --Stephan Schulz (talk) 19:21, 14 November 2014 (UTC)

Agreed. My point was simply that the expensive stuff is not necessary. Visual examination, especially with the aid of a diagnostic reference book, would be enough. Matt Deres (talk) 15:31, 15 November 2014 (UTC)

• The human foot, skull, and teeth are so different from the other apes, I would expect a high-school biology educated layman who could identify these would know right away whether he was dealing with an ape or a human. Likewise, the limb proportions, relative length of the thumb, pelvis breadth, spine curvature, location of the foramen magnum, ribcage shape, and bowing of the legs are quite distinct. Many of these things are diagnostic of human, non-human on their own, and even if you only had a hand, if you knew how to articulate it it would be quite obvious from the thumb and finger proportions. See this website on man vs gorilla, these images at google, and our articles, human leg and comparative foot morphology. μηδείς (talk) 23:20, 14 November 2014 (UTC)

• As for #1, the skull alone should tell the average layman whether it's a human or some other extant primate. However, if you included some extinct primates, like Neanderthals, that would make it tougher. The remaining bones would be harder to identify, in isolation. Only by laying out the bones in the right order to reconstruct the individual would you get a sense for the proportions of the bones, and hence the species. A further complication would be if the set of bones was atypical for that species. For example, the Elephant Man's skull might be difficult to identify as human. StuRat (talk) 15:48, 15 November 2014 (UTC)

Neanderthals were human, they interbred with us. The premise is a full set of adult male bones, so the skull alone is the end of the story. Even comparing the femur and the pelvis is enough to draw an instant conclusion. Once you've found a heel the quiz is over. μηδείς (talk) 19:43, 15 November 2014 (UTC)

The original question was how many of the individual bones could be identified as human - clearly, identifying a set if you know they all belong together is easier. Dealing with adult specimens makes it simpler though - if you don't know the age, the size may not help much, and the differences between species tend to become more apparent with age. AndyTheGrump (talk) 19:56, 15 November 2014 (UTC)

Yes, but we are still presented with a full set of bones from two individuals, not just one carpal bone, which are the only bones I can see as problematic for a layman with a book, although they are bigger in gorilla hands than the are in ours.

If the sets could be sorted (a layman with a book should be able to do this) none of the bones would be mistaken. A forensic anthropologist would not need a lab, as he'd rearticulate the human first, from head down and sine out, then the gorilla, then check for mistakes. The entire anatomy of a human is modified by two things. The human hands are designed to allow the tip of the thumb to touch the tips of all four fingers, not for brachiation or knuckle walking

The rest of the skeleton, the feet, legs, pelvis, spinal curvature, and base of the skull are all designed for a permanent upright stance. our legs are long, straight, gracile and knock-kneed compared to apes. Our pelvis is small compared to our femur, but our head is large compared to our pelvis. The hole where our spinal chord enters the skull is on the bottom, in apes further towards the back.

As intelligent social animals, we don't have fangs for canines, but we do have chins and foreheads, effectively expanding our faces and brain capacity in comparison to apes. The list is endless. μηδείς (talk) 05:02, 16 November 2014 (UTC)

"Designed"? AndyTheGrump (talk) 05:06, 16 November 2014 (UTC)

You obviously know exactly what was meant, or you wouldn't have asked the question. So I'll just assume you are particularly grumpy today, and ignore it. μηδείς (talk) 20:41, 16 November 2014 (UTC)

Design is just an expression, anyway. InedibleHulk (talk) 08:04, November 17, 2014 (UTC)

"Designed" as in "designed by Mother Nature," i.e. by evolution. Not actively designing like an architect, but passive design by natural selection. ←Baseball Bugs carrots→ 13:37, 17 November 2014 (UTC)

He could also be thinking of the design vs engineering distinction. InedibleHulk (talk) 16:11, November 18, 2014 (UTC)

The idea that there's a binary determination between same-species/not-same-species, and that the determination is "can interbreed" is simplistic. Even among extant species that's kind of the "high school" understanding of the subject, and when comparing long extinct species with modern ones the question is even more complicated.

Beyond that, we don't even know if Homo Sapien/Neanderthal breeding normally produced fertile offspring, or just on very rare occasions. (Just like Lion/Tiger breeding will usually create infertile offspring, but on rare occasions the offspring is fertile. Does that automatically make them the "same species"? Clearly not.)

In fact, while the theory that our Cro-Magnon ancestors interbred with Neanderthals has gained a lot of support, it is far from proven, and even among supporters of the theory, many of them believe that it only 'worked' with Cro-Magnon mothers, and didn't work the other way around. Does that make them the same species? Or different species? Neither. "Species" is an arbitrary distinction. Anyone suggesting otherwise for the purposes of nit-picking is more wrong than the person they're nit-picking! 75.69.10.209 (talk) 07:29, 17 November 2014 (UTC)

You contradict yourself. You say a binary distinction is arbitrary, and then you ask us to draw distinctions. You know very well that interbreeding did take place and did produce fertile offspring, and your nitpicking here is way off topic. I said "Neanderthals were human, they interbred with us." Stu could have asked for a clarification, but he did'nt. Presumably you also know ...Nevermind, I am not going to take you seriously. Stu can read biological species concept if he's interested. μηδείς (talk) 18:35, 17 November 2014 (UTC)

Sure, there is a gray area. But given ligers and wholopins and tomacco (nicotine-overdose danger tomatoes(!), "can interbreed (ever)" seems too generous for a useful concept. "(50%/number of matings in a male's life (unpremature death, to satiety)) of inter-group matings with nubile females at random point in menstrual cycle produce 1 fertile offspring" through "has half the rate of fertile offspring as intra-group matings" seems like a more useful gray zone. Sagittarian Milky Way (talk) 20:24, 17 November 2014 (UTC)

Unless your point is that Neanderthals were apes, you're arguing OR about a dead population, so we can't run any experiments, SMW. But we can say that there's more Neanderthal blood out there now than there ever was when they were a distinct population, since at a low estimated end of 2% of the extra-African genome, that's the equivalent of 100,000,000 descendants, easily. See this comparison of Homo sapiens neanderthalensis, and Homo sapiens sapiens. μηδείς (talk) 20:39, 17 November 2014 (UTC)

Further clarify for SMW. If you haven't read biological species concept, I suggest you do. What matters with hybrids in determining species is if they back-breed into one or both of the original populations. If the hybrid form is infertile, or more poorly adapted to its environment than its parents were to theirs, it will be unlikely to have children of its own, and thus gene transfer between the populations won't occur.

But in the case of Neanderthals, the evidence is that like chimps, early bands of modern humans lived in groups of about thirty. Hence, when two groups met, there was probably competition for a territory, and relations would have been unfriendly, so that even if the two groups could interbreed, one might kill off the other before the chance occurred. The general belief is that population pressure from H. sapiens sapiens with its better tool kit drove H. sapiens neanderthalensis extinct.

If the modern humans outnumbered the Neanderthals 20 to 1, a 2-5% flow of genes into the modern human population would show significant enough interbreeding to call the two groups subspecies of the same species according to the biological species concept. Obviously many hybrid offspring did mate with modern humans, or we would not see such a high frequency of Neanderthal genes in our genome. I am not sure how this panned out, but in 2013 a putative hybrid was found in Italy. Given that very few skeletons ever fossilize, this would be significant as well. μηδείς (talk) 22:41, 17 November 2014 (UTC)

Dowel action

What is dowel action on a concrete bean in very simple terms? — Preceding unsigned comment added by 194.66.246.59 (talk • contribs)

It is a "beam", not a "bean". Dowel action is the shear resisted by the reinforcement of the concrete.

We have articles on beam_(structure) and reinforced concrete and rebar and shear strength. Here are a few slides that explain dowel action with illustrations Also, please sign your posts with four tildes, like this ~~~~ SemanticMantis (talk) 22:03, 14 November 2014 (UTC)

November 15

Questions about Coenzyme A

1. Why is it seemingly so rare as a dietary supplement?
2. Do you find any theoretical reason in the claim CoA supplementation increase Lipolysis in some rare cases of "low" lipolysis in compare to "high" Glycolysis (Please, take your time to handle this question and try not to be too much skeptic or general in your answer), Thanks to all the helpers. Ben-Natan (talk) 09:32, 15 November 2014 (UTC)

Humans, like all animals, can synthesize their own Coenzyme-A. As a result, it is very rare to be considered deficient in CoA except in cases of severe malnutrition. In addition, CoA does not handle digestion well, so most of the CoA that you eat (or attempt to consume as supplements) will usually be broken down into smaller molecules before entering the blood. Given that, most of the time people choose to supplement with precursor molecules, such as vitamin B5 (pantothenic acid) or panthenol, which the body knows how to turn into CoA rather than supplement with CoA directly. Dragons flight (talk) 18:38, 15 November 2014 (UTC)

November 16

Width of gas lines.

I was running some gas lines for a unit heater i bought and the manual said i needed larger diameter pipe run depending on the distance the pipe was traveling.

I assume this is to keep a steady pressure, but the pipes throttle at the beginning and the end to a much smaller diameter, so i would think that the throttling would bottleneck the system no matter if i increased the pipe diameter AFTER the throttle.

but apparently it doesn't matter. Why exactly do i need larger diameter piping if i'm going a larger distance? how does an increase of diameter allow for an increase of flow rate? and why does it not matter if there is a reducer on either ends of the pipe?

70.210.70.252 (talk) 02:37, 16 November 2014 (UTC)

Same thing happens with electricity. Longer extension cords need to be heavier gauge wire for the same load. Pipes exhibit resistance to flow based on their diameter AND length. For short runs the differences can be miniscule, but natural gas pressure in household lines is measured in ounces, so even tiny differences can affect the flow rate. 50.126.104.156 (talk) 04:11, 16 November 2014 (UTC)

Just because it's restricted to being narrow at either end (pressure loss for those lengths), it would be even more restricted overall if it were narrow between them too. That is, there is resistance (and increasingly so, as the IP mentions) all along the way, not just a limit based on the narrowest point (as you seem to suggest by the idea of throttling/bottleneck). For lots of gory details, see . Not to say that a very narrow inlet couldn't have an overall limiting effect, but it's also the on-going effect between the ends too. DMacks (talk) 03:39, 18 November 2014 (UTC)

Lot's of reasons and electrical analogy is only one. Another concern is venturi effects. Larger pipes reduce the pressure drop as the velocity is slower. The danger is a high BTU appliance at the end of the run with taps along the way. You don't want your gas furnace to draw air in from the stove burner due to velocity pressure drop. It's important to calculate distance and BTU requirements and taps. There are standard distance/diameter/BTU building code formulas that you can find (I don't have them handy but I've used them before). I believe throttling out of the meter is intentional to maintain a large pressure diff across the diaphragm (outlet is lower pressure during flow and it's not a limiting case). --DHeyward (talk) 22:28, 18 November 2014 (UTC)

Rosetta Orbital Period

Since the comet has such low gravity, will Rosetta be able to maintain a conventional orbit around the comet? If so, how long will that orbital period be? I am guesstimating about a day (24 hours). Altitude 3 miles, orbital path 20+ miles, escape velocity 1 MPH. 50.126.104.156 (talk) 04:05, 16 November 2014 (UTC)

I believe that Rosetta isn't in a 'free' orbit. It does several powered 'turns' in each orbit (I think, every 60 degrees). So, in effect, it's flying a bunch of nearly straight lines at much higher than escape velocity. I read someplace that Rosetta's speed relative to the comet is about 25 meters/second (sorry, I don't remember where I saw that). According to our article, the orbital distance is 29km (roughly) - although at times, they've reduced that to as little as 10km and started out at 100km. If the orbit was circular, then the circumference of that orbit is 2 pi x 29000 meters, which is around 200,000 meters. At 25 m/sec we get an orbital period of around 7000 seconds...around 2 hours. For a more exact answer, we'd need more details about the shape of the orbit and the fuel burns to keep it like that. When it was out further from the comet, I believe the 'natural' orbit was 26 days.

An orbit that long would be useless while interacting with the lander because there would be periods of many days when they'd be unable to communicate. Hence the powered turns. SteveBaker (talk) 15:45, 16 November 2014 (UTC)

Signals from UFOs

If there as many UFOs out there as people would have us believe, why dont we pick up some electromagnetic signals from them via, for instance, the SETI program? Also, if UFOs exist, what do they want?--86.182.54.46 (talk) 13:13, 16 November 2014 (UTC)

We don't hear little green men talking on their walkie-talkies because they are not here. There is almost certainly life out there somewhere (it being a big galaxy and an even bigger universe), but there is no reliable evidence that we are being visited. Alien UFOs, the Bermuda Triangle, the Loch Ness Monster, and ghosts are all more cultural phenomenon than they are scientific ones. Do you want to believe? -- ToE 14:29, 16 November 2014 (UTC)

There are a few scientists who have theorized that there may not be any complex life anywhere else in the Milky Way, based on extremely low values in the Drake equation. I am aware of one that said that the merger of the mitochondrion with the prokaryote was an extremely unlikely event. Other, more commonly theorized values for the factors in the Drake equation compute the likelihood that there is life elsewhere in the Milky Way, but not within communicating distance. Remember that the Milky Way is an astronomically large place. If relativity is correct and the speed of light is invariant, then there are limits to how far intelligent beings, even long-lived ones, would travel. Even if superluminal travel is possible, the Milky Way is still an astronomically large place. Robert McClenon (talk) 21:25, 17 November 2014 (UTC)

As to whether UFOs are a cultural phenomenon, Carl Sagan has theorized that there is something about humans, maybe even in brain wiring, so that humans want there to be other beings with whom we can communicate. In the past, this desire resulted in various sorts of folkloric humanoids such as, in European culture, dwarves, trolls, and elves, having other names in other cultures. In modern times, they are extraterrestrials. So maybe they are both a cultural phenomenon and a psychological phenomenon. Robert McClenon (talk) 21:30, 17 November 2014 (UTC)

If by "UOFs" you were not referring to aliens sighted visiting Earth but instead you were speaking metaphorically of extraterrestrial intelligence in general, and your question was why SETI has not been successful to date, then you should make that clear. -- ToE 14:42, 16 November 2014 (UTC)

Upper atmosphere objects. Do YOU believe these? ]--86.182.54.46 (talk) 14:47, 16 November 2014 (UTC)

There is a large community of people out there who take NASA imagery and "enhance" it. Sadly, because they are unschooled in how to do image enhancement correctly, they make stupid mistakes and generate 'artifacts' that look just like UFOs or alien cities or whatever their fevered imaginations can come up with. My favorite way to demonstrate that is this from a post I did here back in 2009 were I take the period at the end of the original question and 'enhance' it until there is a really clear picture of an alien city, complete with buildings, streets and shadows that are convincingly cast by those buildings! I use it so much, I made a copy on my own website:

• http://sjbaker.org/index.php?title=Alien_City_hidden_in_Wikipedia_post

I've seen photos of UFO's that were the result of this exact same thing. A tiny white speck in an image (could be dust on a lens, or a star or something) get "enhanced" until you get a nice blurry image that looks just like a classic UFO.

SteveBaker (talk) 15:17, 16 November 2014 (UTC)

Aliens are bound by the same laws of physics that we are. Getting from wherever they live to us would take hundreds to thousands of years - and they'd have been unlikely to detect our civilization hundreds or thousands of years ago. It's unlikely that they'd even be able to detect that we're here. With our present technology, we'd be unable to detect a human-scale civilization orbiting a star more than a couple of lightyears away. So:

• "If there as many UFOs out there as people would have us believe"...well that number would be zero...assuming you're listening to people who have seriously thought about it!
• "if UFOs exist, what do they want?"...they don't exist, so the question is moot.

If you really want an answer to the hypothetical question of what it would be like if they DID exist, then I suppose the chain of reasoning is something like:

1. If they could get here at all, they'd have to have some pretty amazing technology.
2. If they wanted to destroy us, and they are that advanced, they could easily do before we ever knew they were there. If they were prepared to spend hundreds of years patiently getting here, they could spend 50 more years to gently deflect a dinosaur-extinction-event sized asteroid to wipe us all out...and we'd never even know they'd done it until we were all dead. So, clearly that's not what they want.
3. If they wanted us to detect them, they could very easily make themselves known by any number of impressive and undeniable ways - and they clearly haven't done that either.
4. So they must want to remain hidden and so they certainly wouldn't go around broadcasting radio signals that they know we can detect.
5. Ergo, if they exist at all, we're unlikely to be able to detect them.

If there were UFO's in orbit around the earth, they might communicate with each other using lasers or some other sort of directed signal that avoided splattering light or radio in all directions. They'd undoubtedly use stealth technology that would prevent us from picking them up with radar or other such tricks.

SETI goes to a lot of trouble to eliminate signals that are too close to earth to be a signal from another star system - so even if they could pick up UFO's, they'd be actively ignoring them...but there are lots of other people out there who track space debris and look for unusual satellite activity from potential (human) enemies who could detect an easily-detected alien ship.

What do they (hypothetically) want? Who knows? We can't detect them.

A species that's capable of all of this wouldn't be dumb enough to show themselves to people by abducting them, doing experiments on them and letting them go afterwards...if they were trying to keep themselves hidden, they're doing a really terrible job of doing that.

All of these sad people with nothing better to do in their lives than make up stories are feeding you bullshit...and until a UFO lands on the Whitehouse lawn...we can probably ignore these reports. People are endlessly capable of deluding themselves and going out and making up a pack of lies to make themselves feel more important...it's a part of human nature.

SteveBaker (talk) 15:02, 16 November 2014 (UTC)

And Steve has only shown one of many types of image distortion only caused by a specific conversion artifact of the JPEG image compression algorithm. There are many, many other image artifacts that can be caused by camera optics, digital sensors, and all kinds of other complicated software processing, all of which are omnipresent on today's digital cameras! If one is looking for noise, noise is easy to find! Nimur (talk) 16:12, 16 November 2014 (UTC)

Yes, exactly. In my example, in addition to the JPEG compression artifacts, I also had our hypothetical UFO investigator use an "Edge enhance" function - which is great at highlighting edges at normal pixel sizes - but when you enlarge the image, you get dark and light fringes along all the edges - which make just dandy fake shadows. I've seen dozens of supposed alien vehicles and buildings that had inadvertently been created from nothing more than edge enhancement and subsequent magnification. SteveBaker (talk) 23:32, 16 November 2014 (UTC)

As far as why an alien species might come to Earth and yet remain hidden, the obvious answer is for scientific study of Earth life, while following a version of the noninterference directive. Earth scientists would absolutely love to find any extraterrestrial life to study, even if it was only as complex as a virus or bacterium. StuRat (talk) 15:16, 16 November 2014 (UTC)

This is a common idea - but if there is an 'noninterference directive', why are they (supposedly) kidnapping dozens to hundreds of humans, doing nasty experiments on them and then releasing them again? If a species that was that advanced wanted to investigate us without being noticed...I really don't think we'd notice them. SteveBaker (talk) 23:32, 16 November 2014 (UTC)

Well, either the infamous "anal probe" part is entirely made up, or perhaps their noninterference directive only applies on a mass scale. That is, they don't want to interfere with the human species, but individuals don't much matter to them. We have similar attitudes towards many Earth species, where we want to protect them, on the whole, but still don't mind killing or experimenting on a few individuals. StuRat (talk) 19:00, 18 November 2014 (UTC)

A few scientists have actually addressed this question, but their scientific inquiries are usually drowned out by the sea of nonsense, fiction, and pseudoscience. As a start, you might look for Intelligent Life in the Universe at your local library. It was written by Iosif Shklovsky and adapted into English by Carl Sagan. The book provides insightful perspectives on intelligent extraterrestrial life from some very intelligent terrestrials. Nimur (talk) 16:21, 16 November 2014 (UTC)

• What has not been pointed out is why there are so many UFO's up there. A UFO is simply any aerial object or phenomena that the observer can not recognise as (say) a Boeing 747, hot air balloon, atmospheric sounder, classified military drone etc. Hence the official term unidentified flying object or UFO for short. Just because a DEFCON alert is issued, does not mean that these (possible) alien objects are of extra terrestrial origin. They might be Russian reconnaissance aircraft or a publicity inflatable that has escaped it tether. Most civilian observers of UFO's don't have radar or any other apparatus with which to objectively record what they witness. If they did, they my well receive electromagnetic signals. Also, people are easy fooled. I saw a youtube video shot at night of which was claimed as an 'obviously' extra terrestrial craft because it was doing maneuvers that no known terrestrial craft could do – except I have seen Airship Industries craft maneuvering the exactly same way. Airships can remain stationary, tilt their noses up and down and suddenly change their apparent shape by turning nose or tail toward the observer. They (Airship Industries) demonstrated their craft to the US defense industry as a possible radar platform – in the very same desert -where the video was shot. It obviously had its internal gas bag lights on – hence it appearance in the sky. This was maybe in order that ground observers could see the maneuvers. These internal lights are there, so that they can serve both day and night as advertising bill boards. But to the audience at this UFO convention, it was by definition a true UFO as no-one identified it for them. If the object escapes the observers experience, it is by definition a UFO and thus there are a lot of them about (both UFO's and observers).--Aspro (talk) 18:24, 16 November 2014 (UTC)

Indeed. As my father-in-law (ex-RAF) used to say, "Any FO is a UFO until it is I". (Any Flying Object is an Unidentified Flying Object until it is Identified) --TammyMoet (talk) 20:39, 16 November 2014 (UTC)

That reminds me of the RAF identification friend or foe system. It worked well at night too, so everybody was told that fighter pilots ate carrots to help them see in the darks, to hide the real reason from the Luftwaffe high command (namely the gravitationally challenged Hermann Göring) for so many successful RAF night-time intercepts. To be pedantic, should mention also, that they donned red goggles whilst on the ground to preserve their night vision and they were very well trained. --Aspro (talk) 21:37, 16 November 2014 (UTC)

There is somewhat of a disconnect between the strict dictionary definition of UFO vs. the way it's used in popular culture. These supposed extraterrestrial vehicles were initially being described as "flying saucers". Donald Keyhoe's organization NICAP called them "aerial phenomena". The term UFO was eventually latched onto, and over time its pop culture meaning usurped its natural meaning. ←Baseball Bugs carrots→ 13:55, 17 November 2014 (UTC)

I really doubt that there are many people left in the world who use "UFO" to mean anything other than alien spacecraft...just like nobody uses "gay" to mean "happy" or "computer" to mean a person who does arithmetic for a living. The word has changed meanings and we're all just waiting for the dictionaries to catch up and mark the old meaning "(archaic)". I'd bet that when someone officially reports an unknown object in the sky these days, the official parties involved steer well clear of calling it a "UFO"...just because every time they do it and the nut-jobs get to hear about it, it's a whole major nonsense-fest. So there are almost certainly new terms used to replace the original sense of "UFO" - maybe "non-specific aerial contact" or something. However, this doesn't prevent people from telling us that the term has some dusty old archaic meaning. Well, I got news for you - it doesn't. Here in 2014, "UFO" means "Aliens spaceship" and any other interpretation is mere pedantry. SteveBaker (talk) 21:28, 17 November 2014 (UTC)

Steve, since this is a reference desk, this is not the place for your scorn and ridicule of people no matter how correct or not you may happen to be in your assessment. Furthermore, you will need a citation for the formal meaning being archaic, since the Wiktionary entries include both meanings: https://en.wiktionary.org/flying_saucer https://en.wiktionary.org/UFO and https://en.wiktionary.org/unidentified_flying_object#English -Modocc (talk) 00:20, 19 November 2014 (UTC)

I also take issue with the

I can't believe that no-one has mentioned it earlier, but the Fermi paradox of relevance here. CS Miller (talk) 13:39, 17 November 2014 (UTC)

All the above is all very well, but how do you explain the strange objects moving at high speeds as shown ON NASAs OWN SHUTTLE CAMERA? as linked to in my second post??86.180.139.169 (talk) 18:12, 18 November 2014 (UTC)

The article UFO sightings in outer space has some references listed that may be helpful to you. --Modocc (talk) 00:54, 19 November 2014 (UTC)

Plant respiration

Where can I find information about plant respiration? I'm looking for specific numbers which give plant respiratory rates during non-photosynthesis periods (aka night) for a variety of crops. A web search gives me several "online answers" type sites which suggest that plants give off CO2 at night at about 10% of the rate that they take it in during the day, but I've not been able to find anything more specific or anything at all authoritative. Our Respiration is a disambiguation page and Respiratory system#Plants doesn't have much useful to say. Do we have more on the subject? -- ToE 14:18, 16 November 2014 (UTC)

Go to Google Scholar and do a search on "dark respiration." There's plenty of info out there. Short Brigade Harvester Boris (talk) 16:14, 16 November 2014 (UTC)

In addition, check out the equations and references used by WIMOVAC, which is a mathematical model for plant physiological processes. The dark respiration model is explained here: . Mihaister (talk) 08:04, 17 November 2014 (UTC)

Thank you very much, both of you. "Dark respiration" was certainly the term I need to be searching on. I haven't found a general table yet, but a few formulae suggest values greater than 10%. For instance, McCree 1974's abstract states that clover and sorghum have a nightly efflux equal to 14% of the previous daytimes influx, plus and additional maintenance component of the efflux which is proportional to the dry weight of the plant, 1.43% of that weight for clover and 0.54% for sorghum (more details behind a paywall). And I appreciate being pointed to WIMOVAC, as it is mathematical modeling I am interested in. -- ToE 12:44, 17 November 2014 (UTC)

Check out Ameriflux and FluxNet. You'll generally want empirical data more recent than 1974, as the eddy covariance tower technology has really changed how accurate measurements of dark respiration can be. Although it's not the primary mission, a lot of research on biofuels and greenhouse gas emissions associated with agricultural production will mention dark respiration numbers. So I'd also try searching google scholar for things like /dark respiration eddy covariance/ SemanticMantis (talk) 15:43, 17 November 2014 (UTC)

Here's a nice paper that covers dark respiration in few different crops . I actually know a small bit about the mathematical modeling of plant physiology (my research expertise is in applied math/theoretical ecology, and this stuff is tangentially related), so fee free to drop me a line at my talk page if you'd like to discuss further. SemanticMantis (talk) 17:46, 17 November 2014 (UTC)

Water on building demolition

What's the point of spraying water on a building demolition? Keeping down dust? Or should I simply assume that they had feared fire? Image context — it hadn't rained in a few days (this was last Tuesday, and there was a moderate rainstorm on the previous Saturday), with unusually high temperatures in the 60°s F, while "surrounding" days were in the 40°s and 30°s F. Although the demolition machine is pausing at the moment of the picture, the pause is momentary; its noise could be heard throughout the downtown for most of the afternoon. Water spraying continued, with both demolition machine and water hitting the building at the same time. Nyttend (talk) 15:11, 16 November 2014 (UTC)

Keeping dust down. Fire is unlikely to be caused by demolition, assuming they disconnected any natural gas lines first. StuRat (talk) 15:21, 16 November 2014 (UTC)

For that matter, dust itself can be a major hazard if it happens to be flammable. Considering what the dust from a building demolition is likely to consist of, you wouldn't expect it to be flammable, but hey, who knows what those people had stored in there? --65.94.50.4 (talk) 09:05, 17 November 2014 (UTC)

We even have an article: dust abatement. Some cities or counties require spraying water on certain types of construction sites. As I recall, in North Carolina, where water was plentiful, they would even spray down the ground around the construction site. Nimur (talk) 15:54, 16 November 2014 (UTC)

Many old houses have asbestos, mold and other toxic material, you don't want that dust to fly to the neighborhood Joc (talk) 17:50, 16 November 2014 (UTC)

My city requires it as well (Ramat Gan - Israel). The reason is as mention above: to keep dust down and to prevent the dust of the environment.213.57.28.207 (talk) 18:01, 16 November 2014 (UTC)

I doubt that if the building has asbestos, just springling water will be enough. Demolishing and decontaminating asbestos contructions is more difficult than that.Senteni (talk) 18:53, 16 November 2014 (UTC)

See Google Street View of the building; it's a modernist structure probably newer than US federal laws restricting asbestos usage. Nyttend (talk) 03:31, 17 November 2014 (UTC)

what is the difference between potentiation and synergism? (pharmacology)

213.57.28.207 (talk) 17:57, 16 November 2014 (UTC)

Is this a homework question?

Let's take a practical example. To make vaccines more potent aluminium compounds are often added. These compounds on their own have no anti-viral effect. Clavulanic acid in antibiotic is another example. Synergism is were 'both' substances have an effect. For example: Alcohol and barbiturates are both depressants, Taken together, the depressant effect is greater because they work together. Incidentally, If one gets a pain around where the liver is, up to two weeks after finishing taking a clavulanic acid enhanced antibiotics, see your doctor to have a yellow card submitted. In the US it would be these people: This bad reactions appears to be under reported. These enhanced antibiotics should not be used as a first line treatments IMHO. I'm not giving medical advice but directing readers to a professional..--Aspro (talk) 18:52, 16 November 2014 (UTC)

Proper adhesive

I have decided to make myself a custom tea infuser but I am struggling to find a proper adhesive for that purpose. Is there any glue for plastic that can have a direct contact with food and withstand up to 100 °C? Will cyanoacrylate do? It works for plastic. Water does not do much to it either. It must be non toxic as is used in medicine. But I failed to find info on how toxic it actually is other than its fumes may be dangerous. Another doubt is about the temperature it can withstand as I don't have much data no that. 128.69.7.196 (talk) 21:46, 16 November 2014 (UTC)

Groan....Epoxied resins are probably better as they are also stronger and the right ones are biologically inert. See: Personally, I would just use a proper Teapot and use real, genuine, lose leaf tea. See:ISO 3103 . Read and do! Lastly, enjoy your first cup of real tea. If you like milk, put it in the cup 'first'. No augments! Milk first.--Aspro (talk) 22:40, 16 November 2014 (UTC)

How about just buying a tea ball ? StuRat (talk) 22:46, 16 November 2014 (UTC)

Sacrilege! The leaves need to circulate. A tea strainer employed during the pouring out, shows one guests that you now how to brew a really good steaming hot cup of tea. Otherwise, you might just as well serve them up with something from a vending machine which fills the cup up with a liquid that is almost, but not quite, entirely unlike tea.--Aspro (talk) 23:18, 16 November 2014 (UTC)

I have given up asking for a cup of tea in the US because all I get is a cup of lukewarm water and a pouch dangling on the end of a string and a little plastic thing that is supposed to contain cow juice but no cup of tea in sight and then they have the nerve to bill me for over a dollar for something that is only good as an insecticide. How is it, that a nation can put a man on the moon but can't achieve the simple art of brewing tea?--Aspro (talk) 23:35, 16 November 2014 (UTC)

Some might argue that the time saved over not obsessing over the precise formulation of warm water with tiny shrivelled up leaves in it is precisely what enabled them to reach the moon. The British effort to get to the moon foundered on the heated debate of when to add the milk in a micro-gravity environment. But then, I'm a Brit who can't stand even the smell of tea...YUCK! SteveBaker (talk) 04:55, 17 November 2014 (UTC)

Astronauts made their way to the moon as the result of the efforts of a small group of people. Saying it was the nation that sent them to the moon is an example of metonomy. Similarly, the nation has never made, or attempted to make, a cup of tea. Cups of tea are made by individuals, not nations. Dolphin (t) 05:31, 17 November 2014 (UTC)

I disagree. Sending the first man to the Moon required that massive tax dollars be spent on the project, which required a large, wealthy population, with the political will to spend that money in that way (or a dictator who gave them no choice). StuRat (talk) 19:49, 17 November 2014 (UTC)

Um...<small> comments are intended to be jokes - no need to take them so seriously. Of course a small group of people were responsible for all of the bravery, the clever science and engineering it took to get to the moon - and a very large number of people had to have the collective will to vote for politicians that wouldn't cancel the entire thing...but remember the <small> font! SteveBaker (talk) 20:39, 17 November 2014 (UTC)

Which plastic? Different plastics need different glues, but in general it's impossible to glue plastic. Cyanoacrylate won't glue plastic very well, truthfully nothing will.

Usually you can use acetone to dissolve the plastic, put the pieces together and wait for the acetone to evaporate, and then they are one piece. (That's how commercial PVC glues work.) Acetone is pretty non-toxic and evaporates really well, so that would be safe for food use. Ariel. (talk) 06:22, 17 November 2014 (UTC)

I own and operate a small business providing a set of very specialized repair services to the construction and home improvement industry in the United States. It is impossible to generalize about "plastics" in a question like this. The performance of adhesives on polyethylenes is completely different from the performance of the same adhesives on polystyrenes. I work most commonly with mineral filled sheet acrylic products, and sometimes with polyester/acrylic blends. In the past, I worked with plastic laminates, where rubber based "contact adhesives" are used routinely, but where urethane adhesives are used in higher-end custom work. In my day to day work, when high performance and a highly inconspicuous seam is critical, we use catalyzed acrylic adhesives most commonly, which we purchase in a wide range of color tints to match the background color of the sheet product. For rapid but more visible bonds, we often use cyanoacrylates. Silicone provides a very strong, flexible bond, but that is not truly inconspicuous. We use hot melt adhesives for temporary tacking and "clamping" but they shouldn't be considered permanent in exposed situations, as exposure to alcohol (such as vodka) will cause the glue line to fail. Construction adhesives (called "panel adhesives" in the U.S.) are strong, inexpensive but ugly. In our line of work, we rarely use epoxies these days, and their performance characteristics vary. Also worthy of mention are UV cured "dental grade" adhesives, which can be tinted and filled with particulates to simulate the substrate, leading to very inconspicuous bonds. Selection of the best adhesive is always a trade-off of factors including compatibility with the material being bonded, strength, appearance, cost, cure time, flexibility, toxicity, availability and things I have forgotten this late at night. There are no easy answers in this area. By the way, acetone is not non-toxic. Sorry. Cullen Let's discuss it 07:15, 17 November 2014 (UTC)

Actually Acetone is pretty much non-toxic. People are always surprised when they hear this, but go and look it up and you'll see. The reason it's mostly non-toxic is that the body naturally contains some, and is able to metabolize it rapidly. (It's not completely non-toxic, don't go drinking it, but as solvents go it's very safe. It's certainly safe to use as a glue and then let it dry.) Ariel. (talk) 19:09, 17 November 2014 (UTC)

I'm not nearly as well-versed about plastics as User:Cullen sounds, but I strongly endorse several of his points: "plastic" refers to many hundreds of different types of material. Even if we consider only those plastics that are readily available to consumers, there are many categories. If we use resin identification codes as a guideline, we can loosely group consumer-grade plastic into six general "types" plus a catch-all "other" category. These categories are completely different kinds of chemicals!

Just for fun, I checked the FDA's web-page for food-safe adhesives. They linked to 21 C.F.R. Part 175, Indirect Food Additives: Adhesives and components of coatings. In the United States, food-grade adhesives must come from that list of pre-approved chemicals; but there is the wonderful catch-all phrase that you will find in almost all FDA regulatory writing, permitting all "substances generally recognized as safe for use in food." In concept, if you used one of these chemicals, your product would be compliant with food safety regulations - which is, needless to say, conceptually distinct from a product that is actually safe. Cyanoacrylate is not on the listing in 21 CFR 175 §105 c(5) and I doubt it meets GRAS requirements. I would wager that cyanoacrylate is neither compliant nor safe for use in food products. Henkel North America publishes a Material Safety Data Sheet for Loctite Cyanoacrylate glue (the kind of CYA glue you'd buy in a hobby model-store). Among the statements in the MSDS: "Not expected to be harmful by ingestion"; "The product will polymerize rapidly and bond to the mouth making it almost impossible to swallow. Saliva will separate any solidified product in several hours. Prevent the patient from swallowing any separated mass;" "Surgery is not necessary to separate accidentally bonded tissues. Experience has shown that bonded tissues are best treated by passive, non-surgical first aid." So, if you follow the advice of this vendor, ... it should be harmless!

If I were building a home-made apparatus for brewing hot beverages for my own consumption, I would be very careful about the materials and glues I used. I would avoid cyanoacrylate entirely.

Nimur (talk) 18:17, 17 November 2014 (UTC)

Cyanoacrylates are routinely used in medical applications, such as an alternative to sutures for closing wounds. Cullen Let's discuss it 03:43, 18 November 2014 (UTC)

... and in temporary repairs of dentures, but it is slowly dissolved by water (and tea). Dbfirs 08:17, 18 November 2014 (UTC)

Cyanoacrylate glues are not only used for skin suturing - that's actually what they were first designed to be used for! It's therefore unsurprising that you can easily get your fingers stuck together while using the stuff! SteveBaker (talk) 17:03, 18 November 2014 (UTC)

November 17

Just asked for a clarification at Uncoupling_protein

Please see. Ben-Natan (talk) 08:17, 17 November 2014 (UTC)

The articles on the individual UCPs listed there each have a brief (or not-so-brief) description of the process. Some are copy-paste wording, others have more/different details. At a minimum, the set of articles should be refactored to centralize the description of this process on its own page. DMacks (talk) 08:28, 17 November 2014 (UTC)

Soapy water

What actually happens to the soapy water that gets on the bathroom floor when people are washing their hands. Does the soap component just evaporate with water? Clover345 (talk) 20:14, 17 November 2014 (UTC)

No. The water evaporates away and the soap is left behind, often leaving a greasy or grimy feel. Same concept as soap scum. Justin15w (talk) 21:21, 17 November 2014 (UTC)

The residue might eventually get cleaned up by people's socks, and then end up going down the drain from the washing machine. StuRat (talk) 22:47, 17 November 2014 (UTC)

Gravitation / Relativity / Cosmology

 person A become at 0.00 the Beam 1    (Altitude between A and B: 5km)
 B 0.00 Beam 1

 A 24.00 Beam 2
 B 23.00 (glock A) Beam 2

 A see the stars at 24.00
 B see the stars at 23.00

 Difference between them is not distance but time stayed in gravitation.

 That is what says general relativity (1.00 = 50 nano).
 Then repeat it 1 billion years.
 Gap between stars 5 years.

 To resume. Someone on a mountain who is 1 billion x 365 days old has 5 x 365 days more than someone (1 billion years old) who is 5km
 below. The difference of nights should be 5 years. The sky from one should be 5 years later than the other one.

 High gravity on A, low gravity on B.

 :*Synchro0 : 00h00 on the two glocks.
 :*Synchro1 : 01h00 on glock A 00h59 on B.
 :*Synchro2 : sunrise, 02h00 on A 01h58 on B.
 :*Synchro3 : sunset, 06h00 on A 05h54 on B.

 The referential was A, now lets with B:
 :*Synchro0 : 00h00 on the two glocks.
 :*Synchro1 : 01h01 on glock A 01h00 on B.
 :*Synchro2 : sunrise, 02h02 on A 02h00 on B.
 :*Synchro3 : sunset, 06h06 on A 06h00 on B.

 B has to compare data with A at 6h00 for A. It means 5h54 for B

the value of a 0.022K capacitor?

i have got non polarized polyester capacitior which has "0.022K400V" printed on it. what is the value of cap in uF? — Preceding unsigned comment added by 223.223.145.15 (talk • contribs) 21:20, 17 November 2014 (UTC)

That's a 0.022 µF capacitor rated for 400V. The letter "K" denotes 10% tolerance. I see that the wiki page on cap markings is pretty slim. See this page for an explanation of component markings. Mihaister (talk) 21:31, 17 November 2014 (UTC)

Properties of PE-HD (High-density polyethylene)

I have carrying cases of this material which came with cordless drills. The drills are now obsolete or worn out and the batteries are no longer taking a charge.

But the cases are like new, aside from a bit of dust. It is too bad the tools were not as well-made as the cases.

I would like to reuse the cases to carry other things. Each side of the case has an outer shell and an inner "insert", molded to fit the original contents. Insert and outer shell are strongly joined together.

If it was possible to soften the insert with heat, it could be reshaped to fit other contents.

The question is, can this material be judiciously softened with heat using for example a small propane torch without it catching fire or giving off noxious fumes? Or to put it another way, is the temperature at which it would soften and become malleable far enough below the point at which it would burn, as to make my project possible?

I think "it must be", otherwise how do people manage to make these cases in the first place. But before trying the experiment, I thought I would ask. Thank you, CBHA (talk) 21:39, 17 November 2014 (UTC)

It's entirely possible they made noxious fumes when formed, polluting the entire area surrounding the factory in China or wherever it was made.

Why not buy another drill, without a case, to match your case ? StuRat (talk) 22:51, 17 November 2014 (UTC)

I would not use a torch, i'm fairly certain the heat required is far below flame torch. Probably a heat gun would do it. There's loads of articles online about it, here's one that might be useful. Vespine (talk) 23:23, 17 November 2014 (UTC)

There are quite a few home-made vacuum forming machines out there (Google "home made vacuum former") - one design uses an office waste-bin, a piece of perf-board and a shop-vac and can be put together with duct-tape.

If you use plastic cut from gallon milk containers, you can soften it with a heat-gun. Make a hole in the side of the trash can and duct-tape the shop-vac hose to it. Duct tape a piece of perf-board over the top of the trash can, place the object you want to make a case for over that, perhaps drap a piece of cloth over it to protect it. Then heat the plastic until it starts to 'sag' and fire up the shop-vac.

Obviously, this is a lot of cost/hassle if you only need to do it once - and it does take a little practice. But being able to do vac-forming at home has MANY uses...and you're using recycled plastic...so you can feel good about doing it!

SteveBaker (talk) 23:49, 17 November 2014 (UTC)

So plastic milk containers (in USA at least) are also HDPE, right? And then it seems you are recommending cutting out the molded plastic inner layer and molding a new plastic insert. That makes sense if we need a close fit, but if OP is willing to cut out the inner molded surface, then the shell could also be fitted with any manner of glued-in foam or plastic inserts that don't have to be custom molded, and could fit a variety of things. Personally, assuming a close fit is desired and the objects are of similar shape to the originals, I'd go at the interior with a heat gun in a well-ventilated area, and then move on the to the other options if that fails. Since the milk container is far thinner than the drill case, I'd worry that softening the inner layer would take a rather long time, and might melt it to the outer shell. SemanticMantis (talk) 00:24, 18 November 2014 (UTC)

Yes, they should have a recycle-2 symbol on them...you might want to check that before you try this just in case you have some weird milk containers in your part of the world. The nice thing about the gallon milk containers is that you can cut around them with scissors and unwrap a piece of HDPE that's about 18" long and 8" wide and comes out more or less flat and with a fairly uniform thickness - which is great for vacuum forming. SteveBaker (talk) 16:58, 18 November 2014 (UTC)

This isn't what you asked, but you can usually open up the battery back, and replace the cells with off the shelf rechargeable AA batteries. Ariel. (talk) 23:52, 17 November 2014 (UTC)

This is interesting, do you have any refs for how/why/in what types of battery packs that might work? (I happen to also have a drill with a similar case and two low-performing battery packs :) SemanticMantis (talk) 00:24, 18 November 2014 (UTC)

The battery packs (except Li-ion) are usually made of ordinary AA (and sometimes AAA) batteries with no name on them and sometimes a solder tab. Open up the pack and take a look. Just trace the connections - most often it's simply all the batteries in series. Then get new batteries and solder them together in the same pattern and put them back in the pack. Soldering a battery is hard (it's a large heat sink, and you have to avoid heating the battery much), but it's possible. Google for instructions on how, a soldering gun is easier than a soldering iron. Ariel. (talk) 00:50, 18 November 2014 (UTC)

In regards to safety concerns, here's a MSDS for HDPE: -- looks pretty safe to my (inexpert) estimation. SemanticMantis (talk) 00:28, 18 November 2014 (UTC)

voltage divider looking to the load like two resistors in parallel

hello, on this page here it reads (among other things): "As you can see, this puts 11 mV of DC across the load. If the load is 32 Ω at DC (...), 0.34 mA is forced through the load. This current can only come from the rail splitter, which looks like two parallel resistors to the load."
I just don't get how the two resistors can look as though they were in parallel, to anything. Do they because the two rails are the same point electrically (are they?) due to the (ideal) battery's internal resistance of 0?
Generally, what is the "algorithm", if there is one, for how to arrive from the original circuit to this equivalent circuit (3rd box from the top here)? Thank you very much Asmrulz (talk) 23:19, 17 November 2014 (UTC)

The "algorithm" for converting a circuit is Thévenin's theorem or Norton's theorem, depending on your favorite representation. An even more generalized representation is to treat the circuit as a two-port network and model the impedance as viewed at any two points on the circuit net. In practice, the process of formalizing these representations means application of network analysis techniques. If you're very practical, you can concoct a lot of "rules of thumb"; if you're very theoretical - or if your hobby is to write electrical CAD software - you can apply techniques of linear algebra (like row reduction, Gaussian elimination, or the Gram–Schmidt process) to re-represent a linear network.

Two resistors in parallel "look like" one single resistor; by the commutative property, one resistor also can also be said to "look like" two resistors in parallel. Nimur (talk) 23:47, 17 November 2014 (UTC)

There's a voltage divider that biases the opamp (it's a single-supply design) in the schematic. The two 4k7 resistors are in series, but in the paragraph discussing the DC equivalent circuit the author says that to the load, they look as being parallel, thus Rsplit=2.35k. That's the bit I don't get....and many others, but this one intrigues me most Asmrulz (talk) 00:37, 18 November 2014 (UTC)

It's superposition. There is a 9V battery across two 4k7 resistors in series, so a certain current flows through them. The virtual ground of the opamp is connected to the midpoint, so it should be at 4.5V. However, as the article discusses, the opamp adjusts its output voltage until 0.34mA flows through the load and into the opamp. That current can be thought of as due to a superposition of the current normally in the 4k7 resistors combined with a current change in each resistor. The top resistor has 0.17mA extra current flowing down, and the bottom resistor has 0.17mA extra current flowing up (that is, 0.17mA less total current in the bottom resistor). That gives a 4k7 × 0.17mA = 0.76V voltage drop at the midpoint, which is the same conclusion as the article (effective power rails of +3.7V and −5.3V). Johnuniq (talk) 02:35, 18 November 2014 (UTC)

What the hell is "4k7?" It is a nomenclature that may be unfamiliar to some readers. Is it a British or European standard? Is there a different US standard (ANSI or MIL) or is it now official in the US? Does the Misplaced Pages manual of style prefer that as opposed to "4.7 k ohm"? Edison (talk) 13:51, 18 November 2014 (UTC)

It's a pretty common convention for component values - I've seen it on both sides of the Atlantic for at least 30 years. When you're writing something like 4.7k quickly, it's easy for the '.' to get lost - and because (especially) resistor values are chosen to be available in decades (4.7k, 47k, 470k). Putting the 'k' where the decimal point would be makes things much less error-prone. SteveBaker (talk) 16:49, 18 November 2014 (UTC)

...and the reason that the op-amp adjusts its output in this way is because of a non-ideal behavior, the input offset voltage. Nimur (talk) 03:24, 18 November 2014 (UTC)

Oops, looking again shows I got the current directions reversed. Each direction I mentioned should be inverted to give a 0.76V rise. Johnuniq (talk) 06:19, 18 November 2014 (UTC)

November 18

Why is Western Europe poorer than USA?

Question moved to the Humanities desk from the Science desk. -- Ariel. (talk) 06:44, 18 November 2014 (UTC)

Is it? According to List_of_countries_by_GDP_(nominal)_per_capita#List_of_countries_and_dependencies the US has the 9th highest GDP per capita of all the world's countries. 6 of those higher than the US are European. Two of those, Norway and Luxembourg’s are twice that of the US. The European Union as a whole, is half that of the US, and it would be ranked 26th in the world, if it was a country. The EU now contains several Middle-European countries that were former Soviet states, and as a result they are bringing the EU's GDP/capita down. The EU is spending its structural fund to help those countries improve. CS Miller (talk) 10:26, 18 November 2014 (UTC)

Visual illusion: red and blue text on black background

When you have both (saturated) red and blue text set against a black background, the red text will seem closer to you and the blue text, as if the text of the two colors were on different planes. What is a scientific explanation for this? --108.36.90.122 (talk) 01:53, 18 November 2014 (UTC)

I can't find our article on it, but found mention of it here Forced perspective: A monocular cue easily taken advantage of by painters is the trend for the color of objects in the distance to be shifted more towards the blue end of the spectrum, while closer objects' colors are shifted toward the red end of the spectrum. A painter can give the illusion of distance by adding blue or red tinting to the color of the object he is painting. Vespine (talk) 02:55, 18 November 2014 (UTC)

I have heard that the eye focuses red and blue at different distances due to refractive index varying with frequency of light, so the lens has to adjust between the two colours. Graeme Bartlett (talk) 11:02, 18 November 2014 (UTC)

Nothing to add except my thanks for asking a question and getting an answer to something that long ago (i.e. pre-Misplaced Pages) puzzled me: at the time I couldn't find any answer or even a mention of the phenomenon. {The poster formerly known as 87.81.230.195} 212.95.237.92 (talk) 13:25, 18 November 2014 (UTC)

• Our article is at Chromostereopsis. It's all about differential refraction, and is based on real physical phenomena in a addition to human perception. (I found it by googling /red blue depth perception/, and also added a wikilink to Forced perspective at the end of Vespine's quote) SemanticMantis (talk) 15:52, 18 November 2014 (UTC)

Is Quantum entanglement necessary?

The universe appears very fine tuned, with only a few exceptions. But what about Quantum entanglement? If quantum entanglement did not occur would there be any noticeable macro differences in the universe? Are there any processes that require it, or are at least affected by it? Or does is it only noticeable in human experiments (I'm sure it occurs naturally, but does it change anything)? Ariel. (talk) 06:50, 18 November 2014 (UTC)

Entangled states arise frequently as a consequence of the indistinguishability of fundamental particles, including in every atom with more than one electron. The resulting exchange interactions have important implications for electron structure and by extension chemistry. In such an example, it is not so much the entangled properties that are important, but rather that an entangled state can exist at all. I can't really think of any examples where the typical notion of entangled states, i.e. that composite object AB is such that measuring A instantly determines the state of B, has naturally occurring macroscopic consequences. It certainly matters for the pursuit of quantum computing and quantum cryptography, but the spooky action at a distance aspects of entangled states may not have a large natural role. However, the fact that fundamental particles routinely form entangled states (and that such states may have different energies than separable states) certainly does have consequences for chemistry and other aspects of physics, so the existence of entangled states definitely matters. Dragons flight (talk) 07:27, 18 November 2014 (UTC)

From a non-physical perspective, I think the answer must depend on how you are thinking of logical necessity and how you think of possible worlds. Also it's good to remember that the fine tuning of the universe is still widely debated, as is discussed with refs in our article. SemanticMantis (talk) 16:01, 18 November 2014 (UTC)

What I'm wondering is if Quantum entanglement did not occur, could there be a universe with stars and life. And it seems there could be. Ariel. (talk) 20:59, 18 November 2014 (UTC)

Note that without entanglement, you won't get an effectively classical world at the macro-scale. The reason why you can't do quantum computing with your PC essentially boils down to the fact that as soon as a superposition of a bit in a "0" or "1" state would arise, environmental degrees of freedom would quickly interact with that and the superposition would vey rapidly become entangled with many degrees of freedom from the environment.

Now, no entanglement at all means that there cannot be any interactions between particles. So, the universe could not support complex structures. Count Iblis (talk) 22:04, 18 November 2014 (UTC)

Cohesion of soils

Which part of the shear strength equation describes the fact that some soils have more weakness planes? Is it C, the cohesion value? 194.66.246.28 (talk) 10:42, 18 November 2014 (UTC)

It might be. What equation are you looking at? Also, not all models of soil strength will be fully three dimensional and correctly capture all forces in all planes. Here is a nice online book on the topic , linked from our article on soil mechanics. SemanticMantis (talk) 19:19, 18 November 2014 (UTC)

Powerful optical resonance in the optical fiber cables

Did it possible, that the optical fiber of the fiber optic cable is able to had the high-frequency superconductivity of electric current of high powerful voltage, if the optical reflectivity and optical refraction in this optical fiber cable will be not had the light spectrum?--Alex Sazonov (talk) 11:44, 18 November 2014 (UTC)

No, optic fibres are not conductors of electricity let alone super conductors. If you try to put a high voltage across the glass in the fibre, you may get an electrical break down with a spark, and the fibre will be damaged, and not so transparent. If your light becomes too strong down the fibre you will heat it up and melt it. Graeme Bartlett (talk) 11:49, 18 November 2014 (UTC)

Did the presence a spectrum in the light wave had hamper to the passage of light wave through the optical barrier (optical medium)?--Alex Sazonov (talk) 12:51, 18 November 2014 (UTC)

The "presence of a spectrum" implies that the light is white or at least polychromatic. This would "hamper" the signal because different colours (= different wavelengths) of light would propagate at slightly different speeds through non-vacuum media like the glass of a fibre-optic cable – this is why it's possible to produce a spread-out spectrum with, for example, a prism – which would cause the signal to spread out and degrade.

For this reason, the light used in fibre-optic cables (where used for communications rather than decoration) is laser light, which is monochromatic and therefore does not have a spectrum. Different wavelengths/colours can be used in the same cable (though its diameter might be optimal for one in particular), and different signals can in principle be sent simultaneously by using multiple wavelengths, one per signal, though this is not yet current practice in everyday communications cables.

Addendum: regarding your initial electrical query – some fibre-optic cables are called hybrid cables, and these do include an electrical conductor in addition to the light-conducting glass fibres. The electricity is used for controlling things like the motors that tilt the aerial that the light signal is going to. The electrical element, however is perfectly ordinary, ambient temperature metal (usually copper), neither superconducting nor carrying "high powerful" voltages. The electricity does not go through the optical fibres.

Disclosure: I work for a company that repairs/replaces co-axial and fibre-optic cables (amongst other things) in mobile (cell) phone aerial installations, and while technically unqualified myself (I do costing work) I have just checked all this with my office's fibre maven. {The poster formerly known as 87.81.230.195} 212.95.237.92 (talk) 13:11, 18 November 2014 (UTC)

The light spectrum is the idea (concept) of optical or magnetic (electromagnetic)?--Alex Sazonov (talk) 13:56, 18 November 2014 (UTC)

Spectrum can be derived using either concepts. Using electromagnetic theory you can calculate in the frequency domain or using normal physical units using time. A Fourier transform converts between the two forms. Optics precedes electromagnetics. You may also be interested in non-linear optics. Graeme Bartlett (talk) 23:05, 18 November 2014 (UTC)

What is a ductless gland

Ductless gland is a redirect to gland. That article's Endocrine glands section says that they are ductless. Are ductless and endocrine just different names for the same thing? 65.210.65.16 (talk) 15:42, 18 November 2014 (UTC)

Yes, the word "endocrine" implies ductless. ←Baseball Bugs carrots→ 18:38, 18 November 2014 (UTC)

Just in case you want to know why they are called ductless literally is because they excrete hormones directly into the blood, lke insulin or adrenaline, rather than things like the kidney or sweat glands that ultimately excrete things into to other organs or externally. μηδείς (talk) 01:40, 19 November 2014 (UTC)

Is melamine specially expensive (and/or difficult to produce)?

I find it amazing how much a whiteboard (dry erase) costs. Isn't there an alternative plastic for this? --Senteni (talk) 20:09, 18 November 2014 (UTC)

It's cheap enough that it is used criminally as an adulterant to fool tests of protein content in things like baby formula. μηδείς (talk) 20:28, 18 November 2014 (UTC)

Looks like melamine can be had for $850-920/metric ton . I'm sure you can find it even cheaper with a bit of search. This is in the same ballpark as other polymeric materials PVC, HDPE, but I don't know if any of these would work well as a substrate for whiteboards. Mihaister (talk) 21:33, 18 November 2014 (UTC)

But you aren't just buying melamine - it's a white powder. You're buying a sheet of wood of some kinds with a layer of polished melamine bonded to it.

I have to dispute your claim that it's expensive though:

On Home Depot's web site they have:

• This 4'x8' sheet of 3/4" MDF for $36.32
• And this identical size and thickness sheets with Melamine coating for $36.56.

So the Melamine coating is 3 cents per square foot...actually, I think it's coated on both sides...so 1.5 cents per square foot. SteveBaker (talk) 03:01, 19 November 2014 (UTC)

November 19

Are African Americans ever included in the study of collectivist and individualist cultures?

General relativity

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