What is the tops speed of any [[Norristown High Speed Line]] rolling stock? --<span style="cursor:crosshair"><font face="Times">[[User:Perseus, Son of Zeus|<font color="green">Perseus, Son]] [[User:Perseus, Son of Zeus/t|<font color="red">of Zeus]]</font></font></font></span> 18:24, 11 January 2011 (UTC)
What is the tops speed of any [[Norristown High Speed Line]] rolling stock? --<span style="cursor:crosshair"><font face="Times">[[User:Perseus, Son of Zeus|<font color="green">Perseus, Son]] [[User:Perseus, Son of Zeus/t|<font color="red">of Zeus]]</font></font></font></span> 18:24, 11 January 2011 (UTC)
:70 miles per hour[http://www.railroad.net/forums/viewtopic.php?f=72&t=67511&start=15] [[Special:Contributions/71.198.176.22|71.198.176.22]] ([[User talk:71.198.176.22|talk]]) 07:07, 12 January 2011 (UTC)
== bubbles ==
== bubbles ==
Revision as of 07:07, 12 January 2011
Welcome to the science section of the Wikipedia reference desk.
The best answers address the question directly, and back up facts with wikilinks and links to sources. Do not edit others' comments and do not give any medical or legal advice.
It has been suggested that the incredible weakness of gravity compared with the other forces is because gravity is the only force which mainly resides in the other dimensions postulated by string theory.Is it conceivable that thought/afterlife/conciousness act similarly as gravity waves, like thought waves, have yet to be detected.
Certainly it's conceivable: you've just conceived it. Whether it has any merit as a scientific theory is another matter. I am not aware of any evidence that thought, whatever it might be, has any properties in common with any of the fundamental forces of nature or the waves that mediate them. --ColinFine (talk) 00:54, 8 January 2011 (UTC)[reply]
Roger Penrose believes that there is an important relationship between consciousness and quantum gravity. The idea strikes me as kind of silly, but it has received a certain amount of attention, or perhaps notoriety is a better word. Looie496 (talk) 01:04, 8 January 2011 (UTC)[reply]
Yes, but Penrose does not claim that he has actual evidence for that hunch. (His metaphysical ideas are controversial, whereas his actual science is acknowledged by everyone to be solid -- and he seems to be perfectly aware of and candid about which is which). –Henning Makholm (talk) 03:00, 8 January 2011 (UTC)[reply]
It strikes me that the burden of proof is that on those who would claim that consciousness is anything more than something materialistic. The brain seems to be a fairly modular thing — there's a strict movement "upwards towards consciousness" (metaphorically, of course) moving from less-to-more complicated brains (lizards, dogs, dolphins, chimps, humans, etc.). This strongly seems to suggest that consciousness is "simply" a very complicated function of a very complicated set of neural wirings. Why one would want to introduce extra dimensions into the equation (other than the desire to not simply be a blot of matter, doomed for a finite amount of time) seems, from a scientific standpoint, fairly unclear. It doesn't mean it isn't possible. But does a lizard have the same physical hardware that you are postulating? Does a dog? Does a housefly? Does an amoeba? Does a virus? And if not, why would humans have it, and no others? Where does it start, and where would it stop? It just doesn't really seem, a priori, to be a very compelling theory, at least to me. It seems far more likely that what we call consciousness is just a measure of specialized computational organs/circuits/what-have-you within the forebrain brain. Circuits we do not at all fully understand, to be sure, but I think we're starting to get close to a general model of things, and it doesn't include anything like you're suggesting. --Mr.98 (talk) 03:43, 8 January 2011 (UTC)[reply]
I'm reading the question as discussing gravity just as an initial example of something the OP has heard may also exist "in other dimensions" according to "string theory".
The actual question is then: could consciousness exist in other spatial dimensions, and if so could our sense of consciousness in this3-space be in some meaningful way "connected" to corresponding consciousnesses in other sets of spatial dimensions?
If I'm interpreting that correctly, then I'd have to say "maybe". I don't know enough about strings and Mbranes and whatever else to know whether in the various theories about them, it is possible for an elementary particle in our 3-space to be a manifestation of a multidimensional vibration that also manifests as "corresponding" elementary particles in other N-spaces. If so, then perhaps the particles making up our brains are mapped onto various other "brains" (including whatever higher-than-3-dimensional corresponding structures might be called). Maybe the complexity of how those vibrations/string/particles are organized in each of those other spaces also produces a consciousness that corresponds to our consciousness in this world.
That would be kind of spooky, wouldn't it be? :) I don't have an answer as to how likely anything like that might be, though – and, remember, "string theory" is still all just a mathematical framework with no empirical support whatsoever or any likelihood of there being any anytime soon, either, afaik. So even if this kind of thing were supported by theory, there would still be little reason to believe it is anything like that in Reality. WikiDao☯04:38, 8 January 2011 (UTC)[reply]
The OP may be interested in Leibniz's Monad theory. Like Penrose, Leibniz had some interesting thoughts regarding consciousness and physics. Also like Penrose, Leibniz's scientific contributions are well respected. In the Monadology he hints that perception and consciousness may be tied to the fundamental units of matter. Or something. I don't think many people subscribe to theory of Monads these days. SemanticMantis (talk) 05:50, 8 January 2011 (UTC)[reply]
It seems to me that the fact that consciousness evolved is a pretty strong argument against the idea that it harnesses any sort of subtle as-of-yet unknown physics. Much of modern physics could have been very useful to biological entities (e.g. lasers, radio waves, ...) but organisms "naturally" using such physics completely failed to evolve anywhere in the biosphere. Why should consciousness be an exception? 83.134.178.145 (talk) 10:13, 8 January 2011 (UTC)[reply]
Still, there is something for science to explain here which, so far, it has not been able to do. There is no workable scientific description of the phenomenon of self-awareness. Everybody is aware of this because one is directly experiencing it - the division of the world between me and not-me and the sensation of being inside looking out on the rest of the universe. We believe that everyone else has this sensation only because we have it ourselves: there is no objective test to detect or measure it. If I claim my computer is self-aware there is no test to prove me wrong. If I claim that my mother is not self-aware, what test could be administered to falsify the claim? One can ask the subject if they are self-aware, but to any question I could, at least in principle, program my computer to give the same answer as given by my mother. Someone famous said this was the last great unanswered question of science. Given that we cannot even detect it, it is a little premature to ask how many dimensions it exists in. SpinningSpark15:14, 8 January 2011 (UTC)[reply]
She probably could, but then so could my computer with the help of a clever programmer so a positive result would not be determinant. Failure to pass the test likewise does not prove beyond doubt lack of consciousness. SpinningSpark16:18, 8 January 2011 (UTC)[reply]
I suspect that most cognitive scientists would see this partially as a problem of definition. We treat consciousness and self-awareness as a "I know it when I see it" sort of affair. We have a very hard time articulating what we think it means in measurable terms. I suspect what we see as one phenomena is really a bundle of things running on different "circuits" in the brain. I still find, though, that there is little to make one think that a non-materialist, non-emergent solution makes any sense. The brain is one complicated piece of hardware — that's true even of far more "lesser" brains than human ones. It strikes me as essentially premature and illogical to assume that we should begin by appealing to things outside of the brain to understand it. There's plenty there that we still need to understand before we conclude that a wholly biological �answer is insufficient.
Incidentally, the computer answer doesn't disprove the original test. The only reason the computer can do it is because a self-aware being made it be able to do so. So there is self-awareness in that system — it comes from the fact that a self-aware being said, "hey, here's how we fool this test." What would be more interesting is if a computer system that was not programmed to do that specifically somehow developed that ability. That would be more akin to the biological analog. ---Mr.98 (talk) 16:52, 8 January 2011 (UTC)[reply]
(1) ... as a side note, despite many attempts, I have never been able to contact customer service; so I suspect the warranty is ineffectual anyway --Senra (Talk) 18:14, 8 January 2011 (UTC)[reply]
Depends. A brain surgeon could probably put something in there without doing too much damage. This is occasionally done. Microchips and such. See Neural implant.
If you're just talking about shoving something in there, then sure, there's a serious danger. But even so, some people survive it. See Phineas Gage!
At the risk of giving medical advice, please don't put physical objects into your brain. It's much more likely than not to harm you, and even small brain lesions can in fact lead to death depending on their location. Prions don't likely have any discernible flavor. 71.198.176.22 (talk) 16:30, 8 January 2011 (UTC)[reply]
It's very easy to put something in the brain without killing someone: see lobotomy. That being said, it's fairly difficult to put something in the brain without appreciably damaging it, and probably requires a medical degree to do so on a regular basis (it literally is brain surgery, after all). Buddy431 (talk) 22:50, 8 January 2011 (UTC)[reply]
Yes. Dynamo says "The first electric generator was invented by Michael Faraday in 1831". It then apparently contradicts itself by mentioning Jedlik's dynamo, 1827. Electric_motor#History_and_development says Faraday invented a mercury motor (which does no useful work) in 1821. I don't know if he was the first to make such a thing, and technically every motor can be used in reverse as a generator, but pushing the wire around in circles in an attempt to generate current sounds difficult, so assuming nobody made any higher-tech motor before Jedlik's dynamo, the motor came first. 213.122.7.185 (talk) 14:53, 8 January 2011 (UTC)[reply]
A partisan advocate of Jedlik introduced many dubious claims based on sources in Hungarian. 19th century histories of motors and generators (in English) only credited Jedlik with some dynamo improvements much, much later than the claims in the Wikipedia articles about Jedlik, motors, and dynamos. We need someone able to read Hungarian to clarify what the sources actually say. Edison (talk) 20:30, 8 January 2011 (UTC)[reply]
I recently heard of an idea: an explosion so massive, that it sends shockwaves through space-time. At subluminal speeds, an observer should be able to see a wave front of Lorentz and time contraction, followed by dilation of both kinds. Is this a plausible idea? --Plasmic Physics (talk) 11:37, 8 January 2011 (UTC)[reply]
Not exactly, but gravitational waves come close. The largest difference from your description is that gravitational waves are supposed to propagate at lightspeed, and that they cannot (as a matter of GR mathemathics) be exactly spherically symmetric, so they wouldn't be generated by a symmetric explosion however massive. –Henning Makholm (talk) 12:51, 8 January 2011 (UTC)[reply]
This is a bit of a complicated question relating to carbon dating and radiometric dating.
Carbon dating is useful for finding the age of relatively recent fossils. The carbon-14 begins to decay, and around 5700 years or so, it's half replaced with nitrogen-14. Every 5700 years (the "half-life" of carbon-14), half the remainder decays. We can measure around how old the fossil is by comparing the amount of carbon-14 to nitrogen-14.
What I was curious about is, would someone be actually able to change the amount of either carbon-14 or nitrogen-14 in the fossil? Is such a process possible?
Of course, carbon dating only works to about 100,000 years ago. For older fossils or actual rocks, you use radiometric dating (as I think it's called). Let's say this mineral is full of uranium-235. After about 700 million years, it's half replaced with lead-207. So 700mya is the half-life of uranium-235. After another 700mya, another half of the uranium-235 has been replaced with the lead-207, and so on. Would it be possible to remove or add bits of either the uranium-235 or the lead-207, like I suggested with the carbon-14 and nitrogen-14?
All forms of radiometric dating (of which carbon-14 and uranium series dating are two of several examples) are subject to errors from contamination, sediment mixing in fossils, and other sources of incidental, accidental, and systematic errors. That is why most radiochemists prefer to date from as many sources of information as possible to cross-check. Intentional contamination seems fairly difficult to me, however. If you're a paleontologist who wanted to pass off a fossil as older or younger than its radiometric age, you might be able to guess about which part of the fossil to contaminate, but I'm not sure how good such a guess could be, or whether such tampering wouldn't be obvious or at least make the radiochemist sample from a different part of the fossil. Other less sophisticated forms of scientific fraud (misreporting measurements, for example) are much more common. 71.198.176.22 (talk) 15:48, 8 January 2011 (UTC)[reply]
You would need to replace a portion of the fossil with something of a different age. If you knew in advance the exact location where the sample would be taken, this could be done (although making it look right would be tricky). Otherwise, you might have to replace the entire fossil. StuRat (talk) 15:51, 8 January 2011 (UTC)[reply]
Yes, because the fossil and surrounding material has to be removed as a sample and pulverized to extract the daughter isotopes of interest. The sort of tampering you're contemplating here might very well be more difficult than fabricating an entire fossil from scratch (which has happened at least a few times in the history of scientific frauds. In the art world this kind of deception would be much easier, because owners of valuable art can restrict chemists from sampling all but certain portions of the work in order to prevent it from being disturbed in a detectable fashion. That allows forgers more leeway.) 71.198.176.22 (talk) 16:19, 8 January 2011 (UTC)[reply]
Most radiometric dating methods would not be able to date the fossil directly anyway. The sequence of rocks containing the fossils can be dated by working out the age of lavas or ash layers interbedded with the sedimentary rock e.g.[1]. It would be simpler just to claim a fossil find from the wrong part of the sequence, but no-one would accept that unless other examples were forthcoming. Mikenorton (talk) 16:01, 8 January 2011 (UTC)[reply]
There also is a strong difference between 14C-dating and most other dating methods. 14C dates organic material. It depends on the fact that 14C is created at a (fairly) fixed rate in the atmosphere, and hence is at a fairly constant level in the atmosphere. Living things are in good equilibrium with the atmosphere. In other words, we know reasonably well what percentage of carbon in living things is 14C. Once something dies, it essentially stops exchanging carbon with the environment. 14C decays. The daughter element, 14N, typically escapes. We determine the age of the object by looking how the 12C/14C ratio has changed (by decay of 14C), without ever looking at the daughter element. Other radiometric techniques work differently. If you look at e.g. K–Ar dating, we do not know the initial amount of 40K. We do know, however, that the daughter element, 40Ar, is a gas, and will escape from molten magma, but not from crystallised rock. So we start with an unknown amount of 40K and zero 40Ar. For dating, we assume that all 40Ar we find is the result of the decay of 40K, and we can hence determine the age (of the solidification event) from the ratio of 40Ar to 40K. The nice thing about this is that we can repeat the experiment with different samples with different initial 40K. If the samples are the same age, and not contaminated somehow, they will all have different absolute amounts of 40Ar an 40K, but all the same ratio of them. In a diagram, the different samples all fall onto the same straight line. This property allows us to detect contamination and problems, or, in the other case, to strongly confirm the dates.--Stephan Schulz (talk) 23:56, 8 January 2011 (UTC)[reply]
It seems to me that it ought to be possible, although I don't know anything specific. It seems to me that by subjecting the material to a flux of photons or other subatomic particles with the right properties, it would be possible to make the 14C decay more rapidly than it would otherwise. This is definitely possible with uranium 235 -- it's the principle underlying nuclear energy generation. It would, however, very likely leave behind substantial evidence of the manipulation. Looie496 (talk) 18:52, 9 January 2011 (UTC)[reply]
Dedendum circles
"dedendum circle diameter must be less than base circle diameter then the part of profile is not involute towards lower side of base circle."
is this statement right for interference of involute profiles.are not the dedendum circles same as base circle.please help. —Preceding unsigned comment added by 59.93.129.167 (talk) 15:59, 8 January 2011 (UTC)[reply]
Can you clarify your question? Our article List_of_gear_nomenclature may help you out. It only explicitly defines dedendum angle, though the graphic for addendum shows a dedendum radius. The base circle radius is not the same as the dedendum radius. The article seems to indicate that the base circle radius plus the dedendum radius would give the pitch circle, but I may be misinterpreting. SemanticMantis (talk) 16:56, 8 January 2011 (UTC)[reply]
The exact pH will depend on the chloride concentration. pH 1.5 seems quite acid for either one, unless you're right out of chloride in the solution, but the antimony will come out before the tin does, that's for sure. Physchim62(talk)02:28, 9 January 2011 (UTC)[reply]
yes, but why would someone taint animal feed with dioxin? If you feed hormones to a cow or chicken you make it fatter, but there is no advantage in mixing dioxin on purpose. So, why did it happen, where did it come from? Quest09 (talk) 20:40, 8 January 2011 (UTC)[reply]
It seems unlikely anyone purposely tained the animal feed (i.e. with the intention of adding dioxins) or at least there's no indication I've seen of that being the case. Various sources [2][3] suggest the fatty acids were intended for industrial (not industrial food!) use only but were mixed with the fatty acids intended for animal feed. Whether this was accidentally or not doesn't seem clear but it's suggested the company knew about the high level of dioxins for a long while [4]. This doesn't explicitly answer why the fatty acids were contaminated but the first source (provided by Edison) says it's not uncommon. Nil Einne (talk) 21:18, 8 January 2011 (UTC)[reply]
It may have been like the antifreeze-in-wine incident of the past - it made someone money. The mineral oil was probably a lot cheaper than food-grade oil. 92.15.7.205 (talk) 21:35, 8 January 2011 (UTC)[reply]
I am a german. The Dioxin (probably TCDD) came from fat for industrial uses, just produced by heating it up. Nobody intentionally, or even accidentally, put a TCDD crystal in, but fats were heated up, dioxin produced, and the fats were only to be used for industrial purposes (e.g. manufacturing motor oil). But somehow the fat company sold it to a company called Harles&Jentzsch, which produces ready-to-feed food for chicken and pigs. Then Galloanserae ate this food, and because the dioxin is not biodegradable, it landed in amniote eggs, and meat. Reportedly, some private laboratory knew about a too high dioxin value from the 19th of March (!) but Harles&Jentzsch says that they only knew from the 27th of December onwards. — Preceding unsigned comment added by Eu-151 (talk • contribs) 17:40, 9 January 2011 (UTC)[reply]
How would fat, made of carbon, hydrogen and oxygen, gain the chlorine needed to make dioxin or PCB just by being "heated up"? I could understand if PCB contaminated oil were used in a heat exchanger, and some of it leaked from its tubing into the fat being heated. That sort of contamination has happened in the past in other countries. Edison (talk) 21:02, 9 January 2011 (UTC)[reply]
You mean a 2d image projected out into thin air? I don't know if there is a general name for them. A company named Heliodisplay makes them. (They spray a thin sheet of mist into the air then project onto that.) But they're mostly just gimmick. APL (talk) 21:56, 8 January 2011 (UTC)[reply]
January 9
Why does any number muliplied by nine add up to nine?
i.e 13times 9=117. 1+1+7=9 and so on.AM radio frequencies in Australia are all multiples of nine.
<e-mail address removed>, 9 January 2011 (UTC) —Preceding unsigned comment added by 118.208.93.193 (talk)
It's to do with us using base 10. If you add the digits of an number, in any base, and end up with base-1, then the original number is divisible by base-1. If you end up with a (multiple of a) factor of base-1, then the number is divisible by that factor. For example
123 (= 3 * 41), is 1+2+3 = 6, so 123 is divisible by 3.
32hex (50 in decimal), is 3+2=5. 5 and 3 are the factors of 15 (16-1), so 50 is divisible by 5.
Let me first of all rephrase your question more clearly. "Any (positive integer) number multiplied by nine" gives you a (positive integer) number that is divisible by nine. What you asking is, why do all positive integer numbers divisible by nine have their digits, in base 10 notation, adding up to 9. Well, they don't. For example, 99=11*9, 990=110*9, 9900=1100*9, etc. are all divisible by 9, but the sum of their digits is 18. The correct statement is: "In base 10, any positive integer that is divisible by 9 has its sum-of-digits divisible by nine, as well". In the example I just gave, the number 9900 = 1100*9, the sum of digits 9+9+0+0 = 18 = 2*9. A simple, non-rigorous proof -- I am a physicist, not a mathematician :) -- is as follows. Imagine you have a number [ an ... a1 a0 ]. For example, if the number is 3456, a3 = 3, a2 = 4, a1 = 5, and a0 = 6. Incidentally, 3456 = 384*9 and 3+4+5+6 = 18 = 2*9. Since we use base 10, the value of [ an ... a1 a0 ] is x = 1*a0 + 10*a1 + ... + 10n*an. Now, what happens when you divide by 9? Let's divide every term separately. 10*a1 = (9+1)*a1 so residue from this term is 1*a1; the next term 100*a2 = (99+1)*a2 so residue of division of that term by 9 is 1*a2; and so on. When you sum up all the residues you get 1*a0 + 1*a1 + ... + 1*an. This is the sum of digits of your original number! The sum of residues equals the sum of digits. So, if the sum of digits divides by 9, so does the full residue; that means the original number divides by 9, as well. --Dr Dima (talk) 02:08, 9 January 2011 (UTC)[reply]
Dr Dima in part says the sum of the digits is 18 but as for all whole numbers the digits 1+8 again add to nine.Regardless of how high the number is taken every time the result is added and re-added it wil eventually resolve to 9. I failed maths at school so please be gentle with me.
Can you clarify your question? As you noted, the sum of the digits of any multiple of nine sum to another multiple of nine, eventually summing to nine if you do it long enough (that is, 4617's digits add to 18, and 18's digits add to 9). This is just as you stated it. — Lomn04:09, 9 January 2011 (UTC)[reply]
Oh, OK, you're referencing this. Dr Dima is being precise about it (in base 10, integer multiple, a formal statement of "might have to repeat to reach 9", etc). — Lomn04:12, 9 January 2011 (UTC)[reply]
See Casting out nines for a more general, related phenomenon. There's an explanation, but it's a bit dense. One thing to note: whenever you add nine to an integer, you always increase the sum of the digits by zero or by 9. Check this to see that it works out. It's intuitively not hard to see why this: if the unit's digit is zero, it becomes a nine, and the rest of the number remains unchanged (for an increase of 9 in the sum). When the last digit is any other number (1-9), the units digit decreases by one, while the Ten's digit increases by one, for a net increase of zero in the sum of the digits. Predictably, the reverse is true in subtracting nine: the sum of the digits either decreases by nine, or remains the same. Buddy431 (talk) 04:18, 9 January 2011 (UTC)[reply]
(edit conflict) This is discussed somewhat at our 9 (number) and Digital root articles, and an interesting use of this property is discussed at Casting out nines. It has to do with the fact that in base-10, 9 is the last digit before you have to start reusing digits (ie. the digits "1" and "0" in "10"). WikiDao☯ 11:21 pm, Today (UTC−5)
This seems like a fairly decisive and understandable answer that deals a fairly decisive blow against reading too much mysticism into such a thing. Does this mean that the digital root of F in Hexadecimal has the same phenomena associated with it? --Mr.98 (talk) 17:30, 9 January 2011 (UTC)[reply]
Ultimately, the reason is that 9 = 10 - 1. --Anonymous, 06:48 UTC, 11/1/11 (or 1/11/11, or...).
Regarding the second component of the question: why are AM radio stations broadcast on frequencies that are multiples of 9kHz? Well, you can broadcast on any frequency you like, but the airwaves are a shared channel (and furthermore, they are regulated by the government - specifically, the Australian Communications and Media Authority). To avoid interference, radio stations need to broadcast on frequencies that are far enough apart that they don't interfere: see frequency allocation for more information. It happens that for voice (and some music), a frequency band of around 9 kHz is reasonable spacing to preserve quality. Actually, it's more likely that the ACMA originally allocated a 9 kHz spectrum with the intention of using two side-bands with 4 kHz of signal, and a 1 kHz "spacer"; this was pretty much only suitable for voice; but that more recent AM radio broadcasters use Single-sideband modulation, especially SSB-SC carrier suppression) to expand their signal to fill out 8 kHz with audio signal (suitable for "low-quality" mono music). So it happens that each frequency is f0 + i×(9kHz), in other words always a multiple of 9 kHz, and f0 = 531 kHz. This 2006 report, AM radio issues from the official regulatory body in Australia, actually specifies that frequencies are spaced by 9 kHz and may use up to 9 kHz in each sidelobe - meaning that there is potential for frequency overlap. (AM radio enthusiasts will note that stations with nearby frequencies are laid out to be geographically sparse and are "encouraged" to suppress the "high frequencies" to minimize channel crosstalk). Nimur (talk) 21:52, 10 January 2011 (UTC)[reply]
I'm doing research for a painting of the lantern room of a lighthouse. I'm having difficulty finding information on how a lamp is lit and when it is lit. In the "lighthouse technology" section of the lighthouse article, it is mentioned that the Dalén light was used predominantly in the 20th century (up until the 60s), but although I followed through to the sun valve article and its external link, I'm not finding what a Dalén light actually looks like, and where a sun valve would be placed on, or within, the lighthouse. I've also found images of first and second order Fresnel lenses (from our own Commons), but not what they look like from above. Are they open at the top to allow heat to escape? (In this example, it almost looks like the answer is "no"). As a mere matter of curiosity, how "hot" was the actual beam of light—could someone stand on the gallery with their back to the lantern room while the light was rotating? Any recommendations for more information on this particular area of the lighthouse would be welcome! – Kerαunoςcopia◁galaxies01:14, 9 January 2011 (UTC)[reply]
It was an acetylene lamp, with the "solar valve" which turned it on and off based on the sun shining on the apparatus. Some results are found at Google book search such as [5] . This appears to be a picture of the Fresnel lens and a lamp from a lighthouse, though it may be a different lamp than the Dalen. It went all around and had a vent in the top, naturally to let the combustion gases out. I did not find info on the lightintensity or heat of the lamp. Edison (talk) 02:25, 9 January 2011 (UTC)[reply]
I found this image [6], which is the man himself standing next to what is evidently a fresnel, though the caption says it's his sun valve, so I assume the sun valve is attached somewhere (there may even be a Dalén light in there too if you're lucky). Unfortunately I couldn't say which piece of apparatus is which. 213.122.40.179 (talk) 02:31, 9 January 2011 (UTC)[reply]
I jumped to the Swedish Wikipedia article on the lamp, which linked to an AGA site with some pictures. The solar valve had a bunch of rods which could heat up and turn off the gas when the sun sas shining. See [7] (in Swedish. Google Translate is your friend). Edison (talk) 02:45, 9 January 2011 (UTC)[reply]
That clarifies the Dalén light perfectly. I was confused because I thought i would actually see it, but the fresnel lens would simply cover it up. A detailed image of the source wouldn't be visible through the lens. Thanks all! – Kerαunoςcopia◁galaxies03:04, 9 January 2011 (UTC)[reply]
It takes perhaps a fifth of a second to voice a known prearranged response when a stimulus is presented, much like pressing a button as a simple reaction time response. If an unknown stimulus letter is presented, the vocal response time is appreciably longer, but still far less than a second. Anecdotally, if one's attention is diverted after an utterance begins, something random and funny may emerge, as if the speech generator were on autopilot and randomly choose a related but unintended word. Certainly the longest time from formulating an utterance to saying it could be many seconds, but the shortest would seem to be a fraction of a second. Mental chronometry researchers have argued for well over a century as to how to determine the time required for internal mental operations, so whether the number you seek is 200 milliseconds or 500 milliseconds or whatever would be open to debate. Edison (talk) 02:10, 9 January 2011 (UTC)[reply]
Thinking Spoonerisms maybe I could rephrase in terms of how many words ahead of the tongue is the brain?
Is English spoken more slowly than many other languages e.g.Spanish?
The question can't be answered in any precise way, because the formulation of words is a gradual and distributed process, and "making speech" is an even more gradual process. For a minimal order of magnitude estimate, you could probably take something on the order of 200 milliseconds. Looie496 (talk) 18:45, 9 January 2011 (UTC)[reply]
The time to start yelling "Stop!" to the driver when a passenger sees a danger ahead of a car, or to yell "Duck!" when some danger is swinging toward people seems less than 500 milliseconds. On TV, there seem to be far more syllables per minute in excited Spanish discourse than in English, but unclear how many words it breaks down into. Some speakers of US English have a very, very slow and drawling mode of speech. Edison (talk) 20:54, 9 January 2011 (UTC)[reply]
The likely reason Spanish seems to be spoken quicker than English to many English speakers, is quite frankly, because they don't speak Spanish. People often fail to realize how fast they speak in their own language. I'm sure Spanish speakers think English speakers speak fast as well. Also some of this might have to do with the different cadence or rhythm of each language. But if you did a words-per-minute count of English versus Spanish, I doubt they'd be very different. 184.99.113.51 (talk) 01:54, 12 January 2011 (UTC)[reply]
It is a disturbance in the field that is moving, rather than the field itself. In much the same way, a disturbance on a water surface causes a wave to propagate outwards from the original disturbance without the whole body of water moving anywhere. Take a look at electromagnetic radiation and come back if you have more questions (the formal mathematical treatment is at the bottom of the article). SpinningSpark 11:46, 9 January 201it (UTC)
it was helpful.but it would be better if ther was an image or anything that can help me understand it better.thanks alot.
The energy applied to the aerial by the transmitter creates a force field around it -so far so good. As the oscillating voltage reduces to zero, some of the field collapses back into the aerial but not fast enough for it all to collapse. What is left of that force field by the time zero potential is reached, becomes detached from the aerial. As the voltage builds up in the other direction the old detached field is repelled and zips off at the speed of light. --Aspro (talk) 15:54, 10 January 2011 (UTC)[reply]
I'm sorry to be pedantic, but "fields" do not experience a force of repulsion or attraction. Electric and magnetic fields cause force on charged particles but they do not induce any force on other fields. What fields do experience when they interact is superposition. So it's not quite fair to say the "detached field is repelled." Maxwell's equations are a set of mathematical expressions that describe the way changing fields create new fields; as a group, these expressions provide a way to mathematically describe how electromagnetic waves propagate. Regarding "why" they propagate, the only real explanation that has physical meaning is something like this: we can observe a set of two related phenomena, called electric force and magnetic force. We observe that these phenomena can occur in a vacuum; they do not require any medium to "exist" or "reside" in. It so happens that if we measure carefully, we discover that when either one of these fields changes with time, that causes a new field of the other type to exist. This interconnected relationship allows waves to propagate, even in empty space. The mathematical expressions that we use to describe the observed measurements of these fields take the form of a wave equation; this stems from the fact that the defining equations of each physical field can be rearranged as a second order differential equation with relationship to the other field. Nimur (talk) 22:05, 10 January 2011 (UTC)[reply]
I should add that we can start one field (or the other) in motion by wiggling around a charged particle according to some pattern. We usually wiggle charges by connecting an antenna up to an electric circuit. Nimur (talk) 22:06, 10 January 2011 (UTC)[reply]
The OP has not indicated that he has any grasp of quantum mechanics. Therefore, I could not see how your reply could bridge over (pons asinorum) from what he could conceptualise to what he couldn't. --Aspro (talk) 20:34, 11 January 2011 (UTC)[reply]
I don't know what level of previous physics education or intuition the OP has; I am just trying to use terminology that would be consistent with a rigorous physical description, even if it introduces or uses concepts the OP is unfamiliar with. Necessarily, complex questions have complex answers. Nimur (talk) 21:56, 11 January 2011 (UTC)[reply]
Well, not really, either. LEDs emit photons based on a behavior of semiconductor physics called a band gap; this is a subatomic process and requires a quantum-mechanical explanation; (essentially, you design a semiconducting crystal with certain properties, and then place an electron into a quantum state that forces it to decay to a lower energy level, emitting a photon in the process). On the other hand, almost all radio transmitters you are familiar with use electronic circuits to move around free electrons as electric current, in a way that is easily explained with classical electrodynamics. The actual mechanism of causing photon-emission is quite different between an LED and, say, an UHF transmitter/antenna. Most notably, LEDs tend to emit monochromatic photons, as opposed to a radio circuit (which, though tuned, can emit very broad spectrum of photon energies). Nimur (talk) 19:54, 11 January 2011 (UTC)[reply]
Yeah. I was just hoping to get away with band gaps' emission being more similar to electrodynamic emission than thermal filaments, but the three are really all different. Uh, you can just say that it produces photons. 71.198.176.22 (talk) 20:22, 11 January 2011 (UTC)[reply]
circular motion
a stunt car makes horizontal circles of radius 20m along the inside surface (with an angle of elevation of 30 degrees) of a vertical cone. the coefficient of static friction between the tires and the road is 0.25. find the possible range of speeds of the car.
In your equations, you are considering the case where the friction force is at its maximum and acting down the slope. This will occur when the car is travelling at its maximum possible speed. You also need to resolve perpendicular to the slope (where the friction force has zero component) to get "n" in terms of mg. I read the question to mean that the radius of the circle is 20m (not 20cos20 as in your equation). You have also omitted the mass from your second equation. Dbfirs12:57, 9 January 2011 (UTC)[reply]
For the minimum speed, consider the case when the friction force is at its maximum possible value but acting up the slope. Dbfirs13:21, 9 January 2011 (UTC)[reply]
I'm not sure that we are happy about 22 almost identical questions either, but from the 1800s up to at least 1960, toilets in the area where I live consisted of a thick board with a round or oval hole smoothly carved, and this was set in stone pillars, usually with a stone front, over a deep pit, usually on sloping ground so that it could be cleaned out occasionally from a lower opening. I don't know whether any of these are still in use, but they were standard when I was young. The variety with two holes side-by-side seemed to fall out of fashion, but my aunt still used one (on her own as far as I know) until about 1970. We can't predict the future, but perhaps the Composting toilet will become more popular as water becomes more scarce during the next hundred years. Dbfirs12:41, 9 January 2011 (UTC)[reply]
For your historical toilets, it really depends 1. where you are asking about (India is not the same as, say, England), 2. what income level you are interested in (are you curious about the very poor or the very rich?), and 3. are you looking for the average toilet or the most advanced (though perhaps not used much) toilet? Dividing it up by decade is probably not helpful, because there isn't going to be very rapid change in the design after a point. (If you lift up the top of your current toilet, you can usually see written inside when it was made. A toilet I had in the early 2000s was from the 1960s, and looked like every other toilet I had seen.) Even if we tried to answer, "what does a toilet look like in 2011?", you'd get a wide spread of responses (I have a fairly average toilet, but it looks very different from toilets I have seen in Germany, for example, and certainly is not as high tech as toilets in Japan). And of course we cannot predict the future, much less a century in the future, so those questions are really not going to get useful answers here. --Mr.98 (talk) 15:02, 9 January 2011 (UTC)[reply]
Part of the geographical variation in toilets is due to whether the location is urban or rural. In general, urban areas get indoor plumbing available earlier than rural areas, so the switch from outhouses to flush toilets in general historically occurs earlier in urban areas earlier than in rural areas. Red Act (talk) 15:32, 9 January 2011 (UTC)[reply]
In a given location the toilets will have a variety of styles in a given year. In US cities in 1910, for instance, the wealthy had flush toilets, but the poor had outhouses. In 1960 in the US many rural homes still had outhouses, but virtually all city dwellers had flush toilets. A farm in 1960 in the US might have a flush toilet in the house and the old privy still there by the barn for convenience when working outside. A 1920 flush toilet might still be in use, and hard to distinguish from one a year old. All the internal parts as well as gaskets to connect the tank to the bowl are still readily available for toilets from the 1920's, so it could still be in use through the indefinite future. A friend has a new toilet which will squirt water to the front or rear area of the user, and will blow warm air to dry the bottom. It has a heated seat as well. Edison (talk) 20:43, 9 January 2011 (UTC)[reply]
You can search at Google Book Search for "flush toilet" or the words without quotes, or "water closet" and restrict the books to a decade. Searching for 1891-1900 I found an 1899 toilet and bathroom. The toilet was much like a modern one, with siphon action, but the tank was elevated on the wall for greater pressure. Anecdotally, this kind worked great. Poorer quality toilets of this period just had "rim flushing," in which water from the mains flowed into the bowl around the rim, with less effective flushing down. As for 1910, "Modern Plumbing Illustrated" (1907) provides some illustrations. Low tanks were replacing high wall mounted tanks in new construction. A larger flush pipe made up for the lower pressure. Here is a description of outhouse at US schools in 1910. Edison (talk) 23:27, 9 January 2011 (UTC)[reply]
Why does America still use the "flap" type of toilet cistern instead of the better siphon method that's been around for a century or more I expect? 92.15.3.168 (talk) 21:44, 10 January 2011 (UTC)[reply]
92.15.3.168's comment is puzzling. What is the "flap" toilet you assume is in use presently in the US? By the 1890's toilets which had some flap or pan which opened and closed at the bottom of the bowl were held in disdain in the references I provided. The preferred method in the US 100 years ago was the siphon, in which a deluge of water from the tank flushed out the bowl. Flaps were used on trains in the 1960's, but no longer. They just dumped the poo on the railroad bed. Edison (talk) 03:41, 11 January 2011 (UTC)[reply]
The spray toilets like the Toto Washlet are fairly common in Japan, but why are they hard to enter the market in America? I thought most decent Americans would want the utmost personal hygiene, so why are they still slow to accept the fabled spray-toilet? --70.179.178.5 (talk) 12:13, 9 January 2011 (UTC)[reply]
Bidets are common in many countries, but I don't think I've ever seen one in the United States. I'm not sure there's a concrete reason there other than, "it's not what we're used to."
That's obviously just because I'm not used to it — my toilet experience has, my entire life, been a "dry" one, and adding water to that just feels exceedingly strange.
Attempting to drive a horseless wagon felt exceedingly strange for a time too, and horses thought they were so strange, they'd feel spooked at the sight of a wagon moving without a horse. --70.179.178.5 (talk) 13:01, 10 January 2011 (UTC)[reply]
Add to the fact that our restrooms are all designed for a single toilet and you have an infrastructure problem. (Not with the integrated bidets, of course. But with bidets in general.) I'm not sure why you'd think that Americans would "want the utmost in personal hygiene" — hygiene is a very culturally relative thing, and most Americans would probably not recognize the bidet as really adding all that much in terms of hygiene.
We once didn't recognize soap as being all that necessary for our personal health & hygiene either. For a time, we even thought that any doctor who washed their hands of the so-called "spooks" were "quacks." --70.179.178.5 (talk) 13:01, 10 January 2011 (UTC)[reply]
My experience is that Americans view the toilet gadgets of the Japanese as an extreme form of using technology to not necessarily useful ends (so to speak) — Americans, from my anecdotal experience, seem to have very little interest in "improving" their toilets, and see the existing models as working pretty well on the whole. --Mr.98 (talk) 17:21, 9 January 2011 (UTC)[reply]
Skidmarks still strain and even end relationships; the bidet-seats would save them. The water used from the bidet's enema washes would be far cheaper than laxatives. We once thought having a computer in our own homes was an extreme form of technology. We also thought having a GPSnavigation aid in our own vehicles were extreme technologies once. The time must come for Americans to realize how useful it would be. --70.179.178.5 (talk) 13:01, 10 January 2011 (UTC)[reply]
Living in the U.S. and having avoided such features, I think that my gut reaction when looking at this article is that something is going to go wrong - that feces-tainted water is going to spray off in all directions and shoot out and get all over my pants, etc.
Plus, I think that the nozzle in a public restroom will get sprayed with feces-tainted water from a previous user, opening a potential route of infection.
Once the nozzle retracts, it gets sprayed so that all impurities are rinsed off. The water that cleans off the nozzle may be heated, and/or even soaped! --70.179.178.5 (talk) 13:01, 10 January 2011 (UTC)[reply]
I should further add that the (citation needed) sentence "In order to determine the anal position, 300 male and female employees of Toto were surveyed during development." really raises a red flag, because there's a lot more variety of body shape and size in the U.S. than in Japan. Wnt (talk) 18:39, 9 January 2011 (UTC)[reply]
Toto is an international corporation. Some of the 300 were foreigners, and they must've used all sorts of body shapes. Possibly, some of the employees were also made to bring their children in for tests to make sure it would work for all ages, body shapes and sizes. Japan has sumo wrestlers too, so some of them may have been test subjects as well. --70.179.178.5 (talk) 13:01, 10 January 2011 (UTC)[reply]
In my limited experience with Googleplex men's bathrooms, the lobby restroom toilets are indeed Washlets, but the employee toilets are ordinary American models. -- BenRG (talk) 21:50, 9 January 2011 (UTC)[reply]
2) Americans associate dry butts with "clean" and wet butts with "dirty". That perception's not easy to change.
I never once thought that. I knew from first learning about these spray-toilets that the water spraying from the nozzle is clean from the get-go, so it rinses off what life throws our way. (My BioBidet BB-i3000 model also has a liquid soap dispenser for extra good measure.) --70.179.178.5 (talk) 13:01, 10 January 2011 (UTC)[reply]
70.179.178.5, please don't break apart other people's posts to you - it makes it very difficult to see who is posting what. Instead, just reply at the end, adding an extra : to the front of your reply to make attributions clear. While I'm sure it's unintentional, your replies read as if you want to start a debate or make a sale. Matt Deres (talk) 14:58, 10 January 2011 (UTC)[reply]
Agreed. It's really pretty irritating, and trying to counter back endlessly why you think Americans should like these is entirely the wrong approach if you want to understand why they don't like them. --Mr.98 (talk) 23:04, 10 January 2011 (UTC)[reply]
Humans in general are (for the most part) creatures of habit, but there seems to be an additional psychological aversion to, and even disgust of, alien anal cleansing habits (said aversion unaddressed by the article). I remember how strange health faucets seemed when I fist saw them (traveling in Thailand and Malaysia), but now I wouldn't be without one and have installed them in my US home -- and I cringe slightly at the prospect of using only toilet paper at public toilets. Still, I wouldn't want a washlet's robotic arm doing what I'd rather do myself, not to mention the fact that a washlet may cost a hundred times more. Likewise, I wouldn't object to using an electric toothbrush, but I don't want a robotic arm moving it around in my mouth. -- 119.31.121.84 (talk) 01:47, 11 January 2011 (UTC)[reply]
It's not an "arm," it's a nozzle spraying the rinse. Sure, it can move up-down, left-right to make sure every last square millimeter is cleaned off, or it can even vibrate/pulsate to massage you. I've found them to be quite a vast step up from the old way.
I suspect 70.179.x.x is making a good rebuttal; I should emphasize that, per request, I was giving a simple psychological snapshot of an American perspective, not making an argument that I planned to defend. Though I should point out that from an American perspective no part of the inside of a toilet is generally thought of as clean, even, I suppose, if it is retractable. For example, the happy bachelor expects that when cleaning a toilet (an action of last resort, typically undertaken only when attempting to recover a security deposit) one will find the underside of the rim covered with fairly thick amounts of feces and/or strange dark aquatic flora which one trepidates to identify. Wnt (talk) 06:58, 12 January 2011 (UTC)[reply]
Wet-Bulb Temperature vs Dew Point Temperature
Are these two the same? There are articles on both, with subtle references to each other but to me they seem to describe more or less the same thing. What is the difference between these two? 196.210.162.116 (talk) Eon —Preceding undated comment added 12:50, 9 January 2011 (UTC).[reply]
I'm no expert on thermodynamics (I am getting all this from just reading our articles) so I might have this wrong but my reading is as follows. To find the thermodynamic dry-bulb temperature the air is cooled by allowing water to evaporate into it until saturation is reached. This process is adiabatic, ie no heat is input or removed from outside the system. To find the dew point the air is again cooled (but not necessarily adiabatically) to saturation but no "extra" moisture is injected into the system. The first conserves heat, the second conserves moisture. The numerical relationship between these is given at psychrometric chart. SpinningSpark21:06, 9 January 2011 (UTC)[reply]
Brilliant explanation, except you said dry-bulb in one spot where I think you meant wet-bulb. Now that you provide both explanations in the same paragraph I can see the difference. I had actually thought that the two are equivalent even given your explanation. But clearly there is a difference, for example if hot air had 0% relative humidity then it would have a dew point of absolute zero but a wet bulb temperature still somewhere above that. Maybe this is a bad example because water would freeze at those low temperatures but the example sets my mind at ease. 196.211.175.2 (talk) 08:24, 10 January 2011 (UTC) Eon[reply]
As our coma article explains, the state that neurologists call coma rarely lasts for more than a few weeks -- is almost always resolves either into brain death or a persistent vegetative state. When the broader literature speaks of somebody being in a coma for years, it almost always refers to what neurologists call a persistent vegetative state. (Sorry for the pedantry.) Looie496 (talk) 18:40, 9 January 2011 (UTC)[reply]
So, are there notable people in vegetative state? I guess so, a list would be interesting. Also, a list with the longest coma states, and people who recovered from them. emijrp (talk) 19:20, 9 January 2011 (UTC)[reply]
The request seems to be for notable people presently in a persistent vegetative state. I fear it would include a vast number of folks who have shaped our world; writers, scientists, actors, businessmen and soldiers who are now in their 90's and awaiting death, being spoon fed, and having their diapers changed, not knowing who or where they are. We hear about them only when they die. Edison (talk) 06:00, 10 January 2011 (UTC)[reply]
Imagine a "List of people who were gaga at the end." Perhaps Reagan, Churchill, and many more. In most cases, their family pretends they were still alert at the end. Perhaps their handlers use their names to endorse their old favorite causes, despite their senile dementia. A lack of public appearances is one indicator that they have lost it. Edison (talk) 06:04, 10 January 2011 (UTC)[reply]
See section 22.3
in above reference on balancing of reciprocating masses .the book mentions that only cos component of primary unbalanced force is balanced by the additional ass B.
it really dosent looks so,because the sine components of mass m and mass b are also in opposition to each other . kindly clarify my point ,or please pint out where i am making a mistake.
Kndly do help me :in which direction is the secondary unbalanced force acting? —Preceding unsigned comment added by 59.93.128.223 (talk) 14:04, 9 January 2011 (UTC)[reply]
The way I read it, the sine component produces an unbalanced force perpendicular to the line of stroke, and this is indeed not balanced by the mass at B, so the best solution is a compromise but I haven't read the article carefully, and I've never met the theory before, so please forgive me if I have misunderstood! Dbfirs17:16, 9 January 2011 (UTC)[reply]
Dissolving gases in liquids
I have a system where a gas is added above a liquid (for example methane above water) over a very wide range of possible partial pressures. I need to predict the concentration of the gas in the liquid at equilibrium. Henry's Law tells me that the concentration will be proportional to the pressure at least for relatively low partial pressures. So, this leads me to two questions, A) what is a good reference for Henry's Law constants (for example, the proportionality constant for methane and water at 25 Celsius), and B) is there a way to predict (or at least lookup) when and how the behavior will diverge from Henry's Law at very high partial pressures? For the purposes of this question, one can assume the gases are chemically inert in the liquid. Dragons flight (talk) 14:28, 9 January 2011 (UTC)[reply]
There's certainly no "one-size-fits-all" solution. You can easily calculate Henry's Law constants for a variety of gases from the data at this site, assuming linear solubility over 0–101.3 kPa (a fair assumption for a sparingly soluble gas like methane, a bad assumption for a reactive gas like chlorine). As for extrapolating those constants to higher pressures, well, you do so at your own risk! If the data are important for an application, they need to be measured. Physchim62(talk)02:18, 10 January 2011 (UTC)[reply]
I've watched in a Nova science show that when an object approaches the speed of light, any additional energy that gets put into moving the object changes into mass. (E=mC^2) --Tyw7 (☎ Contact me! • Contributions) Changing the world one edit at a time!16:33, 9 January 2011 (UTC)[reply]
Yes, that is one way of looking at it, though experts tend to frown on the formula that I learnt in the 1960s: because treating the "extra" like normal mass can lead to error. Another way of looking at the situation is to treat the extra as "super-kinetic energy" (since the ½mv2 of normal kinetic energy is the preceding term in the Taylor Expansion), but the preferred modern approach is to talk about momentum where the relativistic momentum is given by :. See Mass in special relativity for details. Dbfirs17:03, 9 January 2011 (UTC)[reply]
I assumed that the OP was asking about the "energy changing into mass" concept, but I agree that there is no question mark. Dbfirs17:50, 9 January 2011 (UTC)[reply]
Do not try this at home. A new fully charged "12 volt" car battery might have an internal resistance of 0.01 ohms, and a short circuit current of 1200 amps. A 1 foot piece of #12 wire (.205 cm diameter) has a resistance of about .002 ohms, so it would not limit the short circuit current much. The contact resistance of the wire to the battery terminals might limit the current more than the resistance of the wire, since the wire end would spark and melt when the connection was made. A #12 wire would heat up red hot and melt, and the battery might explode. A much smaller wire would also melt or vaporize. A battery may have hydrogen gas present above the liquid, which could explode due in a short circuited battery and cause fragments of the battery and the acid to fly around. Edison (talk) 20:34, 9 January 2011 (UTC)[reply]
In spite of the risk it is not uncommon for a mechanic to dab lightly the tip of a grounded wire to a battery terminal as a test for voltage. The hot arc at the point of contact melts the lead terminal and the wire tip, hopefully breaking the connection before more damage occurs. It is also possible but not recommended to use a car battery for electric Arc welding where the short-circuit arc is deliberately maintained. Cuddlyable3 (talk) 23:50, 9 January 2011 (UTC)[reply]
Many years ago I was working on a Volkswagen Beetle with a 6V battery. I was using a shifting spanner (adjustable wrench) and inadvertently shorted the two terminals with the spanner. Big spark and buzzing noise for the half second until I whipped the spanner way! There was no explosion and the spanner didn't melt. However, it gave me an unpleasant surprise and since then I have been sufficiently careful that it hasn't happened again. Dolphin(t)02:13, 10 January 2011 (UTC)[reply]
A farmer bought a 4-pronged fork and a tractor battery. He tossed them in the trunk (EN. boot) of his car and they bounced around on the bumpy ride home. When he got home he found a cloud of smoke and a 3-pronged fork. Cuddlyable3 (talk) 04:32, 10 January 2011 (UTC)[reply]
I never really appreciated electricity, despite sticking my thumb in a 120 volt light socket, until I connected a cliplead incorrectly on a 110 volt DC circuit and saw it light up. Edison (talk) 05:54, 10 January 2011 (UTC)[reply]
Bailey and similar bridge girders are made of sections that are less than about two or three metres long. What is the mechanism that joins these sections together into a single girder? The bottom of the girder, at least, will be in tension. I have not been able to find any photo or diagram of the joining mechanism. Thanks. 92.15.24.111 (talk) 18:33, 9 January 2011 (UTC)[reply]
The 8 15/16" long x 1 27/32" diameter panel pins[9] (which fit into matching holes in each panel) bear the tension between each section[10] and are themselves secured by much smaller safety pins. 71.198.176.22 (talk) 15:40, 10 January 2011 (UTC)[reply]
Here, in [11] see the inner tab of the knuckle joints on the corners of the upper two of the four panels stacked closest to the camera, and the outer slots on the bottom two of those four. The tabs fit into the slots, the panel pins[12] fit through the matching holes, and then a safety pin goes through the hole in the panel pin. The finished assembly is fairly visible along the right side of [13]. 71.198.176.22 (talk) 11:42, 11 January 2011 (UTC)[reply]
I'm no dentist, but it strikes me that the apparatus there would be very hard to use to get all of your teeth cleaned sufficiently. You'd have to turn it at some very odd angles to get the ones in the back done well. In general I suspect the rotational angle of a modern electric toothbrush would be much more superior to the simple vertical axis of the one shown. But again, this is just a conjecture on my part. --Mr.98 (talk) 21:19, 9 January 2011 (UTC)[reply]
Genealogy
Hi all! I'm not sure if this belongs here or somewhere or else, but here goes. I think I may have found a long-lost cousin, but I'm not sure. She shares my maternal grandmother's maiden name. Apparently, this girl's mother's aunt's sister may be my grandma's sister. What is this girl's relation to me? I checked the cousin article, but I'm still not sure. Thanks for the help! --68.101.253.196 (talk) 20:19, 9 January 2011 (UTC)[reply]
This all depends on whether the girl's mother's aunt was a blood relative of the girl. It might have been the aunt's husband who was the blood relative, in which case you are not related at all, you just have relatives in common. The sharing of the maiden name doesn't make any difference here unless the girl's mother and grandmother retained their maiden names on marriage (or were unmarried). Assuming that the aunt was not an aunt by marriage, and that there are no half-sister relationships, and that the aunt's sister is also an aunt, it seems possible that you could be second cousins because the aunt's sister could have been your grandmother or another sister in the same family, but you would probably not have explained the situation in such a complex way if this had been the case. If your mother and the girl's mother had been first cousins (their mothers being sisters), then they would probably have known this (though I actually know two first cousins who don't know each other). We need to construct a family tree with names to be sure, but a public forum is perhaps not the best place to do this. Dbfirs20:48, 9 January 2011 (UTC)[reply]
If I understand your discription right, then your grandmother is their great-grandmother, this would make the relative your first niece once removed. --Plasmic Physics (talk) 20:55, 9 January 2011 (UTC)[reply]
... but a "mother's aunt's sister" isn't a "great grandmother" -- or have I mis-read the confusing relationship? Dbfirs21:57, 9 January 2011 (UTC)[reply]
Sorry, I was confused a bit. I correct myself, the relative would be a second niece, not a first niece once removed. By the sound of it, the aunt, sister and grandmother are all siblings, your mother and the other mother would be cousins. You and ayour second cousin should share a set of great-grandparents. --Plasmic Physics (talk) 22:21, 9 January 2011 (UTC)[reply]
Yes to all of the above except, as one person put it in an article on another site about use of isomers of dangerous drugs in OTC medications (such as nasal inhalers) "there is no magic chirality fairy that will turn L-isomers into D-isomers." You would have to use some form of synthesis. Apparently as per the article above it is an expensive (comparatively) process but is known. 65.29.47.55 (talk) 00:43, 13 January 2011 (UTC)[reply]
Tooth Decay/Heat
Since evolution would not have anticipated heating food and drink,have any comparative studies been done on tooth decay of wild primates and other related animals to that of humans?
Don't know about studies, but, since the teeth cool down to body temperature rapidly, the only risk is if the temperature change is so extreme that it actually cracks a tooth, due to uneven thermal expansion. StuRat (talk) 23:30, 9 January 2011 (UTC)[reply]
If you are heating and cooling your teeth so drasticly that they crack, you're probably setting your face on fire anyways, so I doubt that your cracked teeth are your most pressing concern. --Jayron3201:00, 10 January 2011 (UTC)[reply]
Well there ya go. So a) Don't immediately follow hot tea with ice cream 3000 times in rapid succession, and b) don't gargle with liquid nitrogen, and you should be pretty safe from thermal cracking of your teeth. --Jayron3201:27, 10 January 2011 (UTC)[reply]
For the record, our article on Homo ergaster says that species may have been the first to master fire; they lived around 2 million years ago and evolutionary pressure would have had some impact in the time between then and now. Comet Tuttle (talk) 19:33, 10 January 2011 (UTC)[reply]
January 10
Single Photon/Electron emision.
Articles showing the wave/particle duality of electrons and maybe photons demonstrate aiming individual particles at slits with a resultant interference pattern.However they never explain how single particles are produced and aimed(especially a photon which I assume cannot be magnetically influenced). John Cowell. 118.208.9.92 (talk) 00:59, 10 January 2011 (UTC)[reply]
Thanks for reference,(though the maths was beyond me) ,the articles did not explain how to produce,aim and fire the particles from an engineering standpoint. John Cowell. 01:36, 10 January 2011 (UTC) —Preceding unsigned comment added by 118.208.9.92 (talk)
Presumably this: [14] reference (from the article) would be at that level of detail. If not, it itself would have references you could follow to earlier descriptions of such methods. --Jayron3201:56, 10 January 2011 (UTC)[reply]
Laser and polarization filter
All the photons in a laser are entangled together, right? Does that mean that if one of the photons passes through a polarization filter, the rest will as well? In other words, do they always either let all or none of the light through? — DanielLC03:17, 10 January 2011 (UTC)[reply]
No, all the photons in a laser are not entangled. And if you had a beam of entangled photons, just because one went through a polarization filer does not mean all of them do. And finally if you did send all the photons in a beam of entangled photons through a polarization filter it does not mean all or none - quite the opposite, some will go through, some won't, and some will end up in sort of a partial state of going though and not going though. But in total, half will end up going through and half won't. Additionally a polarization filter is (one) method of creating entangled photons in the first place. Ariel. (talk) 09:20, 10 January 2011 (UTC)[reply]
In days of yore we were told that atoms had a nucleus with electrons "orbiting" at a relatively large distance away.In an airforce avionics lecture we were taught that electrons changed orbit/energy levels/shells/fuzzy balls/etc emitting or gaining energy depending on circumstance and this involved travelling a very small but finite distance in zero time.I feel a warpdrive coming on!
John Cowell.04:10, 10 January 2011 (UTC) —Preceding unsigned comment added by 118.208.9.92 (talk)
I've not seen anywhere that de Broglie waves aren't limited by the same physical laws as the objects that are associated with them? --Jayron3216:53, 10 January 2011 (UTC)[reply]
An electron occupying an atomic orbital is in a de Broglie wave more properly associated with a probability distribution than a point, even considered as a solution to the Schroedinger equation. Therefore it can be said to be occupying disjoint space simultaneously whereas a more point-like nucleus can not, until several orders of magnitude smaller distances are considered. 71.198.176.22 (talk) 17:28, 10 January 2011 (UTC)[reply]
Yeah, but that doesn't mean the electron "jumps" magically between different points instantly; it just means that a single electron is "smeared out" over a certain volume of space; it is partially and simultaneously in multiple locations. --Jayron3219:29, 10 January 2011 (UTC)[reply]
Guys, this is easy. Apply Heisenberg's uncertainty relation. Whether the jump is instantaneous or not is irrelevant, because we can't measure it instantaneously. Any change of the quantum state ΔE is accompanied by a characteristic Δt. Specifically, the change in electron energy follows the relations laid out in this section; the more "resolution" you want on the energy scale, (in other words, if you want to measure a single quantum of energy), the more time your measurement necessarily gets smeared out over. Nimur (talk) 22:52, 10 January 2011 (UTC)[reply]
Motor oil leakage in cold weather
I bought my car knowing that it had some problems; among these is a slow oil leak. I've been advised that a repair job might be difficult (no clue where the leak is, for example) and that it's not at all necessary, so I take care of the situation by checking the oil regularly and adding more when necessary. As we've descended into the North American winter, I've noticed that the oil level changes less between times that I check it, even though I don't think to check it as frequently. Is there any chance that the cold weather reduces the rate at which the oil leaks? Please note that the rate at which I was losing oil before, while not great, was far faster than could be accounted for by the oil that I wipe off the dipstick when I check it. Nyttend (talk) 04:20, 10 January 2011 (UTC)[reply]
Motor oil (see article) may increase Viscosity at low temperature, especially if it is not fresh, which could explain the slower leak. Your real problem is to locate the leak so is a web page that can help[15]. Warning: Are you sure it is only motor oil leaking? A leak of brake or transmission fluid is a serious fault that needs immediate attention. Cuddlyable3 (talk) 04:54, 10 January 2011 (UTC)[reply]
With modern multigrade motor oils the viscosity shouldn't change that much. Maybe one of the rubber seals is stiffer? Or the cold is causing parts to shrink a bit tightening the gap? Or it could simply be self-sealing (i.e. gunk is blocking the hole) - you won't know till summer. Ariel. (talk) 05:49, 10 January 2011 (UTC)[reply]
Cuddlyable — I know that it's motor oil, because the levels on the engine oil dipstick go down (or went down) from week to week. Nyttend (talk) 23:19, 10 January 2011 (UTC)[reply]
dear sir,
i have an idea of to produce electricity by using mechanical energy that is produced when a cycle wheel rotates so what are the apparatus to be used and the design and the important thing is that it should be a low cost model —Preceding unsigned comment added by 117.204.69.78 (talk) 09:05, 10 January 2011 (UTC)[reply]
I think you mean a generator. But the hard part (meaning the expensive part) is not producing electricity, the hard part is producing the mechanical energy. How are you going to make the mechanical energy? Ariel. (talk) 09:09, 10 January 2011 (UTC)[reply]
It should be noted that this is only as eco-friendly as your diet and lifestyle. Using beasts of burden (human beings, in this case) is not a very efficient or a priori eco-friendly way to utilize mechanical energy. --Mr.98 (talk) 14:10, 10 January 2011 (UTC)[reply]
Presented only as information, and not a suggestion that anyone should undertake the experiment: It would be possible to generate a respectable amount of electric power with a stationary bike. A single bike alternator only produces a small amount of electricity, with more output voltage at higher speed. It is only designed to power the headlight and taillight of the bicycle, putting out only 6 watts or so. Their efficiency is only 70% or so, per Bicycle lighting. One might collect several old bicycle alternators, and mount them on the bike frame so they can be placed in normal contact with the rear tire. One could connect a bridge rectifier to each one to produce DC electricity. Various connections could produce 12 volts DC to power a battery charger. An inverter connected to the 12 volt battery could power small appliances such as a small TV. Peddle like hell, so that you are producing a small fraction of a horsepower of mechanical energy. I would not expect more than 60 watts of output for an extended period if I were peddling such a bike generator. Some experimenters have gone a step beyond and connected a stationary bike to a salvaged 12 volt car alternator, perhaps via a v belt rather than the low efficiency connection of a bike alternator rubbing on the tire. The alternator might be able to put out 100 watts, depending on the model used, but the human power source might limit the long-term output. Edison (talk) 03:23, 11 January 2011 (UTC)[reply]
If the stationary bike I use is accurate, it really is not all that difficult for a reasonably in shape human to produce 150 watts of power for 30 min. If you want more then that, you might want to see if Lance Armstrong is busy. Googlemeister (talk) 14:22, 11 January 2011 (UTC)[reply]
If you merely reverse the polarity of the single phase AC power supply to an electric fan, it will still rotate in the same direction. Consider the phase relation of the armature and field, to find a way to reverse it. If it had a three phase power supply and motor, switching any two of the supply connections would cause it to rotate in the reverse direction. Edison (talk) 03:06, 11 January 2011 (UTC)[reply]
It depends on the kind of motor it has. You'll probably have to open it and change wiring. A D/C fan can be reversed by changing the polarity. A/C fans are more complicated and it depends on the exact type. Ariel. (talk) 20:21, 10 January 2011 (UTC)[reply]
AC power doesn't have a "polarity" of course, just one terminal that has a higher potential with respect to the earth, so there is no point in reversing the incoming wires in a fan that runs on mains electricity (unless it happens to be an enormous 3-phase industrial fan as mentioned above). Altering the internal circuitry might work on some AC motors, but should only be attempted by a professional who understands the circuitry. For a DC motor, there is no need to open anything to reverse the motion, just change the polarity at the source. In either case, best safety advice is don't open it. Dbfirs17:06, 11 January 2011 (UTC)[reply]
Hiding gold in ink
In the Mr. Monk Gets Married episode of the popular television series, the secret hoard of gold is found to be in the ink of a prospector's journals. Monk says that the prospector had melted down the gold and mixed in black ink, and that "any amateur chemist could do it". Now, I have my doubts - I would expect the ink to evaporate explosively on coming into contact with the molten gold (at over 1000°C). So - is there a way in which an amateur chemist could have hidden his gold in ink? DuncanHill (talk) 11:59, 10 January 2011 (UTC)[reply]
Gold paint can be made with powdered gold. I'm not sure of the technical difference between paint and ink, but it could take several volumes of writing to use up one ounce of ink, so I can't see how this would be practical way to conceal any appreciable quantity of gold.--Shantavira|feed me13:01, 10 January 2011 (UTC)[reply]
He did write a lot of journals. I should have mentioned that the ink needs to look like ink and not like gold, as the purpose was concealement. DuncanHill (talk) 13:07, 10 January 2011 (UTC)[reply]
I haven't tried this, but it might work with finely powdered gold and high-carbon ink because the gold powder would tend to sink under the layer of carbon. This would not be a very practical method because the concentration would need to be low to conceal the gold. If Monkthe prospector had the facility for melting gold, then casting it into an everyday object and painting it to match would be a better option, though care would need to be taken that the object could not be "lifted" (in either sense). Dbfirs13:21, 10 January 2011 (UTC)[reply]
He had a clue! The prospector had let it be known that his gold could be found in his journals, so everyone assumed you had to read the journals, which Monk started to do. However, they were full of inconsequential ramblings, and eventually Monk realised that the volumes were very heavy, and he realised that the gold was literally in the journals. DuncanHill (talk) 13:32, 10 January 2011 (UTC)[reply]
Gold(III) chloride is a green liquid that can be mixed with ink. What one need to avoid however, is anything which will cause the gold to precipitate out as metal. Also, it is a salt and will corrode your nib. --Aspro (talk) 13:48, 10 January 2011 (UTC)[reply]
The journals were discernibly heavy? Think of how little ink goes onto a page compared to the weight of the page. Even if the ink was ten times heavier (gold instead of carbon), would you be able to notice the difference between a journal and a journal with writing on? APL (talk) 21:27, 10 January 2011 (UTC)[reply]
The weight must have been increased by at least 7000 ounces of gold, even at today's prices. That's a lot of ink to hide so much gold! Dbfirs11:01, 11 January 2011 (UTC)[reply]
I tried Googling for it; no straight answers. Also, I called the WORLD HEADQUARTERS of it in Chino, and the lady who answered didn't know either. Does anyone know? Is there a supergoogle they can use to figure out why Alorica closed its doors in Manhattan? Thanks. --70.179.178.5 (talk) 12:22, 10 January 2011 (UTC)[reply]
This isn't really a science question. Alorica appears to be a privately owned corporation, which means that (in the United States), the corporation is not required to disclose anything about their business and financial decisions. If they want to close an office, or set fire to a pile of cash, they aren't really accountable to anyone over it. Nimur (talk) 22:58, 10 January 2011 (UTC)[reply]
My laptop has been all paid off. It was manufactured in Fall 2007 so thanks to the rapidly-depreciating nature of these devices, hardly anyone should think it's worth stealing. (I'd still use a Kensingtonlock on it.)
So let's say I find a 24-hour coffee shop to camp out in, since I probably might not have much of a choice. I may still have my debit card that I have now, so I could still get started somehow.
However, I might not have all that much money in the first place, so on this laptop, how do I get started on a very low-overhead online business, in order to get back on my feet and earn a living again? What ideas do you have in regards to that? (Ebay's out of the question; when much of my possessions would already be gone, there isn't much to sell on there. Besides, their fees are the highest of any auction site and I'm only allowed to sell up to 100 items/$5,000 a month. I need to be able to make money without physically possessing much.) --70.179.178.5 (talk) 12:29, 10 January 2011 (UTC)[reply]
I can't really help because I had the same idea when I was living on an income below the poverty line, but I didn't find any good money-making schemes. My reason for replying is just to warn you to beware because most of the "money-making schemes" are really just scams designed to defraud you either by asking for money up-front or by paying ridiculously low rates of pay. I hope you have more success than I did, and I hope you don't end up homeless. Is there no ordinary work available in Compton? Dbfirs12:43, 10 January 2011 (UTC)[reply]
What he said. If there were straightforward and reliable ways to make an adequate living from a coffeeshop using only a laptop and their wireless internet connection, I suspect you'd see a lot more people doing so. Unless you can actually come up with a solid business plan for yourself and you have some particularly desirable (valuable!) skills that you will be able to market and use effectively over the Internet, then you're probably better off just getting a job working at the coffee shop. TenOfAllTrades(talk) 13:58, 10 January 2011 (UTC)[reply]
Proof-reading, translation, website design, marketing consultancy, but you have to have the necessary skills. Either use your existing contacts to drum up business or sign up with agencies. Itsmejudith (talk) 14:34, 10 January 2011 (UTC)[reply]
If you have to ask, then I really doubt if you have the entrepreneurial qualities to exploit the opportunities out there. For instance; you dismiss Ebay -why? You might not have stuff but you do have time on your hands and other people are always throwing away stuff and may even be willing to pay you to take it away, which you can then sell on Ebay. Via Ebay you can advertise your website (you do have a web site don't you) on which you can also advertise other peoples products and get another income stream (but this will be usually peanuts)(that said, the local cat-house might offer good rates of several dollars a click if you can show you are attracting lots of local traffic to your site). You can also use it to advertise your own personal services which you can do because of all that time on your hands. With time on your hands you can travel out and about -take a compact camera with you which can also record video. Keep an eye out for trouble and sell the footage to news channels. Even local papers might of a few dollars for a good action photo. Bank robberies in progress etc., you can syndicate world wide for bigger bucks. Upload to the studio immediately from the scene of the crime. If your out every day you will see these opportunities. Also, for every 20 local businesses you ask. about two will be willing to have a sort video advert posted on Youtube (taken with you camera – with your personal testimony voice-over that it is the kebab shop in Compton or whatever ). Again place links to your website (and their's of course) etc., etc. You have to work as hard at it, as any other job. Plan for being told NO! 25-30 times a day. The few that say 'yes' will more than make up for those that say no. Do lots of small cheap jobs and those bigger ones will just come along by themselves unexpectedly. Don't forget to put money aside for paying taxes.--Aspro (talk) 14:37, 10 January 2011 (UTC)[reply]
You can Turk. Its generally small amounts of money, but if you have time and select jobs wisely, you can make a reasonable amount of cash doing it. --Jayron3216:09, 10 January 2011 (UTC)[reply]
A lot of web money-making opportunities are not simple things that you can turn on like a switch. For instance some blogs and webcomics are profitable, but only after years of slowly gaining a readership and a following. They're essentially creative businesses that have to be slowly built up from absolute zero. APL (talk) 17:49, 10 January 2011 (UTC)[reply]
I think the safest choice is to put all your energy into getting a normal job working 8 hours a day, and once you have landed that and thus secured the means of survival, in your spare time use the laptop to learn a computer-based marketable skill like web design or computer programming or database programming or 3D modeling or the like. Do whatever you can to network with like-minded professionals. After a year or two of such training, depending on how far you progress, you may have enough experience to build a decent portfolio and apply for jobs in a more lucrative field, thus beginning a career. Comet Tuttle (talk) 19:20, 10 January 2011 (UTC)[reply]
Agreed. Tech job stuff is high risk (and no benefits) even in better economies, and when one has resources to fall back upon. The best "no skills required" jobs I've seen lately are working at Whole Foods, which has excellent benefits plans and huge discounts on food. But really anything is better than trying to make money from your laptop when you have no home. (The "ghetto paparazzi" option of Aspro is perhaps the silliest one I've seen so far.) --Mr.98 (talk) 19:46, 10 January 2011 (UTC)[reply]
If you want a lucrative job that can be performed in a cafe, just write the next hyper-successful work of popular fiction. --Anonymous, 06:59 UTC, 1/11/11 (or 11/1/11, or...).
Cheapest source of ethanol for sterlisation
A while ago, I asked where is the cheapest place for ethanol (for sterilisation) in the UK and it now seems to me that we already have a reasonably-priced source, compared to alternatives that I've checked. The cost is £6.60 for 2.5 L analytical grade (100%), or £2.64/L. How much do you pay per litre at your laboratory? ----SeansPotato Business15:40, 10 January 2011 (UTC)[reply]
Linearization
Hi! I have to linearize a hyperbolic graph. Data: x:1,2,3,4,5,6,7,8 y:8,1;4,7;3,1;2,0;1,4;1,0;0,7;0,5. I've already squared x bu got a hyperbola again. Please help. — Preceding unsigned comment added by Atacamadesert12 (talk • contribs) 18:02, 10 January 2011 (UTC)[reply]
Do you want an equation for a linear approximation for this graph? You can use Microsoft Excel to construct a linearization for you; here are instructions from Purdue University and from the official Microsoft Office help page. A linear least-squares fit from Microsoft Excel produced y = -0.9536x + 6.9786 with an R2 of 0.8 (in other words, not a very good fit - but hyperbolae aren't linear! So this poor fit is not unexpected). Knowing something about your purposes would help us pick a better methodology; you can linearize with other techniques than least squares; I would vote for a tangent-line at x=5 or x=6 value; or a set of two linear segments to account for the "steep part" and "shallow part". You could also linearize the logarithm of your hyperbola. Nimur (talk) 23:16, 10 January 2011 (UTC)[reply]
Oh, I thought he was trying to derive the best-fit equation to the hyperbola using the linear method. You can often do so by brute force; if you do stuff like square or take the inverse or take the natural logatithms or some combination thereof, and replot the data, if the manipulated data is linear you can back-derive the best-fit equation for your original data. Its a common method used in deriving the Rate equation in chemical kinetics, the integrated rate law is manipulated and plotted to see if the graph is linear; if it is the order of the original rate law can be determined. --Jayron3223:56, 10 January 2011 (UTC)[reply]
Those responses are correct but they leave out an important factor. A solid object exposed to the sky on a clear night will lose a lot of heat by radiating to space -- the result is that things like cars can become a lot colder than the surrounding air. If there is a cover over the object, it radiates heat back, greatly reducing this effect. Even a cloud cover will considerably reduce radiative heat loss. Looie496 (talk) 20:59, 10 January 2011 (UTC)[reply]
Solutions of [Mn(H2O)6]2+ in water are pretty much colourless to the naked eye, at least all the ones I've seen. You can see the pink colour in the solid because the solid is more "concentrated". Physchim62(talk)00:19, 11 January 2011 (UTC)[reply]
The rule of thumb is that a buffer is effective in the range of plus or minus one pH unit from its pKa. Glycine has a pKa of 2.34, but I have seen some more or less reliable sources list its effective range as 2.2-3.6. Why would a buffer have a skewed effective range like this? ike9898 (talk) 21:52, 10 January 2011 (UTC)[reply]
Amino acids, being zwitterionic, are far more complicated. Also, you have not designated the complete buffer system. Are we talking about, say, a sodium glycinate/glycine system? An ammonium glycinate/glycine system? A glycinium chloride/glycine system? --Jayron3222:04, 10 January 2011 (UTC)[reply]
I don't know about the terminology but I suppose it would be glycinium chloride/glycine (essentially a solution of glycine acidified to pH 2.2 with HCl). Does the presence of the amine group matter? The proportion of these groups that are protonated won't change appreciably between, say pH2 and pH3. ike9898 (talk) 14:28, 11 January 2011 (UTC)[reply]
I think part of the issue is that the "+/- 1 pH unit from the pKa" is a rule of thumb that works best, like all chemical systems, in simple situations where there isn't a lot of factors to consider. I am just speculating here, but the deal with glycine is likely some sort of hydrogen bonding effects whereby the effective pKa of the glycine in buffer is slightly different than the actual pKa of glycine as measured by other methods. I did find this source which lists the same effective range you did, but I do not know what methods they used to arrive at that range. --Jayron3216:00, 11 January 2011 (UTC)[reply]
The term "critical mass" in relation to repopulation
Is "Critical Mass", as a term to describe the number of a population in a natural environment, that would be needed to repopulate itself, actually used as such in science?
Google Book-ing the terms "critical mass population extinction" brings up a few examples of the term being used in this context, but it seems to be used as a metaphor for the physics term, not a normally used one in ecology. This is probably because, as Findlay indicates, there are alternative terms that are more precise. The MVP is more complicated than a simple repopulation issue, no doubt because there are more factors involved for actual animal populations, and because unlike fissioning nuclei, there are inbreeding issues to take into account. --Mr.98 (talk) 22:58, 10 January 2011 (UTC)[reply]
Small populations have decreased per-capita growth rates due to Allee effects. In sexually reproducing animal populations, Allee effects can arise from problems finding mates once the population drops below a critical threshold. As others point out, 'critical mass' is not a phrase commonly used by ecologists. SemanticMantis (talk) 23:45, 10 January 2011 (UTC)[reply]
I'm asking in comparison to most of the discovered exoplanets, including the rocky kepler10b. These tend to be extremely close to their parent star, often closer than mercury is to our own sun. Are planets of such small orbits simply easier to locate, or is our solar system truly unusual in this respect? 131.215.3.204 (talk) 00:00, 11 January 2011 (UTC)[reply]
The reason that discovered exoplanets are closer to their respective stars is that our methods of discovering them require that they be located so close to their stars. Presumably there are lots of different ways in which solar systems may be organized. The type of organization we find in our solar system may be far-and-away the most common way they are organized, we just don't know because there's not really a good method to find a solar system which would look like ours. We definately have no way to locate an Earth-sized planet in the goldilocks zone using those techniques. --Jayron3200:08, 11 January 2011 (UTC)[reply]
Doing a bit more research, it turns out that discovering a solar system like ours may just be possible; a similar system to our own has been discovered around the red dwarf star Gliese 581, the smallest identified planet around which, Gliese 581 e, is the smallest ever discovered exoplanet and is about 2x the size of earth. So it looks like, as of about 2009 we may have the means to correct the biases in the data I noted above. We probably just have a lot more looking to do. --Jayron3200:13, 11 January 2011 (UTC)[reply]
It's a bit like asking what is the most common animals in that hay-meadow? The cows, the rabbits, the field mice, the crickets? We can't (yet) detect Earth-like planets 1AU from a sun-like star. The radial detection method favours massive planets, close to the star. See some earlier queries here. CS Miller (talk) 00:55, 11 January 2011 (UTC)[reply]
Reread the Gliese 581 article. There are several "Earth-like" candidates around that star's habitible zone. That's just one system. Given time and refinement of methods, we may be able to do better in the not-so-distant future. Still, most of the stuff so far discovered is of the "massive planet rediculously close to the star" type, for the reasons you note. --Jayron3201:25, 11 January 2011 (UTC)[reply]
I read that it was discovered by the Kepler space telescope and "Kepler relies on the 'transiting' technique, which looks for planets that pass between their host star and the Earth." [17]. This implies that planets that go round their star faster are easier to spot - to spot one with an orbit the same length as the earth's, Kepler would have to stare at the star for a year. I assume (apologies for guessing) a planet closer to its star will generally have a shorter orbit. Kepler-10b's orbit is less than a day. 81.131.69.118 (talk) 05:59, 11 January 2011 (UTC)[reply]
Dammit, I even read that recently while trying to absorb what "gravitational mass" is (for the question about falling feathers and hammers). "The concept of active gravitational mass is an immediate consequence of Kepler's third law of planetary motion", as it says in the Kepler section of mass. These things are hard to take in. 81.131.69.118 (talk) 06:23, 11 January 2011 (UTC)[reply]
Lewis structure
Hi, I'm drawing the Lewis structure for NO2–. Because of the – there is one extra electron available to use, but who gets it? I was taught oxygen is more electronegative than nitrogen and thus should get it, but which oxygen? In the structure I made it actually makes more sense to give it to the nitrogen, then you have one unbonded pair per atom and two covalent bonds and one coordinate bond between each oxygen and the nitrogen in the center. Thanks. 24.92.70.160 (talk) 02:20, 11 January 2011 (UTC)[reply]
Yes, an oxygen gets it. In simple terms, the nitrogen is double-bonded to one oxygen, and single-bonded to one negatively-charged oxygen. In reality, they are both half-bonded, but this can't really be shown in a drawing. --T H F S W (T·C·E)02:46, 11 January 2011 (UTC)[reply]
See nitrite for a more thorough description, and some pictures. The bond order of each nitrogen-oyxgen bond in the nitrite ion is 1.5; they are the same length and strength; but a lewis structure does not allow you to draw fractional bond orders so you have to use resonance structures to fudge it. In your lewis structure, you should make sure each atom obeys the octet rule (that is some combination of 4 bonding pairs and lone pairs). --Jayron3203:10, 11 January 2011 (UTC)[reply]
They can be if you draw them as free radicals. Indeed, I think it is standard to draw both nitric oxide and nitrogen dioxide as have whole-number bond order and leaving the nitrogen as being electron deficient (with seven electron). Such a lewis structure would highlight the tendency of these compounds to spontaneously dimerize, as they do. --Jayron3204:26, 11 January 2011 (UTC)[reply]
Sorry, by "good-looking" I meant "obeying the octet rule". Yes, you can draw them as radicals, and the dot on the nitrogen is a lot more common than the dotted line bond used in those articles. On the other hand, they don't dimerize with the eagerness you'd expect from the run of the mill free radical compound; and consider that molecular oxygen is also sort of a free radical compound despite its deceptively simple Lewis structure. The Lewis structure is a lovely idea, but these compounds are what show its weaknesses. Wnt (talk) 06:49, 12 January 2011 (UTC)[reply]
Well, the theory of evolution has been added to and modified continuously during the century and a half since Darwin's initial writings. I am not sure what you mean by "loop holes". Can you elaborate on what sort of things you are looking for? --Jayron3204:28, 11 January 2011 (UTC)[reply]
Well, the theory suggests the mutation of species from one form to another. It may seem childish, but does it actually imply extinction of one specie while giving rise to another more developed and well suited for surroundings? I do actually think the answer to be negative, but i'm still doubtful about my own opinion,
Also the intermediate stages that the theory speaks of seem to be absent, or maybe well disguised. Why does no one see the intermediate stages between us humans and the apes, when we are supposed to be evolved from the apes themselves and they still do exist?! —Preceding unsigned comment added by 116.73.242.109 (talk) 04:47, 11 January 2011 (UTC)[reply]
To answer your first question, no, it does not mean that one species must go exitinct. It may, or it may not. For example, many types of Crocodiles have remained essentially unchanged as a species for millions of years. Certain specific crocodile species likely descended from earlier forms, and both the earlier form and its descendent still exist today. Also, evolution doesn't produce better forms on an absolute scale; it produces forms better suited to the environment contemporaneous to that form; but since the climate of the earth often changes dramatically as well, what is "best" at one time is not "best" at other times. Also, the fact that new species are evolving is itself changing the environment. As far as intermediate forms go, we actually do have some very good records for intermediate forms for some species lines, and not so much for others. One explanation is that of punctuated equilibrium; that is that sometimes changes happen rapidly, often too rapidly to leave much data behind, while at other times changes happen slowly and gradually. The other explanation is that we likely only have, as yet, found evidence of a tiny fraction of the total number of species ever to exist; there are clearly enough "complete" lines with transitional forms to show the concept of evolution works as expected, but the lack of a complete record of every species ever to exist isn't itself a problem for evolution. Heck, we don't even have anything close to a complete record of every species alive today, not even CLOSE. Never mind those species likely to have lived in the past. Finally, human evolution does not show that humans evolved from (modern) apes. Humans and our modern ape cousins evolved from a common ancestor, not one from the other. In that sense, chimpanzees and humans are equally "evolved" from that common ancestor, we are just evolved in different manners. There are hundreds of intermediate forms between humans and that "nearest common ancestor" with Chimpanzees. The best candidate right now for the closest common ancestor between humans and chimpanzees is probably Nakalipithecus or Ouranopithecus. To an earlier question you had, that doesn't mean that such an ancestor had to die out. It did in the case of modern humans, but there are many times in the fossil record where earlier human species lived for long periods of time side-by-side with an ancestor species. --Jayron3205:09, 11 January 2011 (UTC)[reply]
Depending on how you look at it, many forms of genetic engineering may provide us with 'loop holes' that let us get evolution's positive effects without the negative effects, and without waiting a zillion generations.
If a scientist can design a new bacteria on his computer instead of waiting for one to evolve naturally, then I'd call that a loophole. In the future that same loophole may let our species skip the more tedious aspects of the process. APL (talk) 06:42, 11 January 2011 (UTC)[reply]
I wouldn't call sex tedious :) Anyway punctuated equilibrium does explain that you don't get all intermediate steps at equal frequencies. The theory is basically that the species gets suited to its surroundings like water at one end of a pan. If the pan is slightly tipped the water may run over to another section. New species would normally arise in the same way by the environment changing or a new environment being exploited which leads to a quick burst of change followed by equilibrium again. Dmcq (talk) 10:50, 11 January 2011 (UTC)[reply]
Sure, but even those faster changes are going to be slower than a scientist fiddling genes on his computer and injecting them into an egg. Especially as the scientist can create organisms with traits that do not benefit the organism. (bacteria that produce some chemical that's worthless to the bacteria but valuable to us.)
I would call that a loophole. I dunno if that's the sort of "loop hole" the question-asker was looking for, though. He might have just been looking for a "Oops, didn't carry the two, turns out God did it after all." sort of thing. APL (talk) 15:17, 11 January 2011 (UTC)[reply]
Negative Matter
Can darkmatter be negative matter? How would negative matter interact with a blackhole? If the antiproton is made from antiquarks, then what would a negative proton be made of? Does negative matter fall under the domain of supersymmetry? --Plasmic Physics (talk) 05:12, 11 January 2011 (UTC)[reply]
Another name for negative matter is antimass. Antimass is to easy to confuse with antimatter; I chose to use negative matter. If negative matter was more then just a hypothetical placeholder concept, then it would be measured in kg⊖, or if you want to go relativistic, J⊖ s2 m-2.
Another question, would negative matter be visible, since it would radiate negative photons which, are gravitationally repelled by positive matter hence, darkmatter? --Plasmic Physics (talk) 06:51, 11 January 2011 (UTC)[reply]
Well, if you invent concepts like antimass and negative photons, you can give them any properties you like. It is like asking "I just drew a purple dragon, what does it eat?" 88.112.59.31 (talk) 07:06, 11 January 2011 (UTC)[reply]
We have a negative mass article, which has some discussions about its properties. However, it also states that it is a hypothetical concept, so although it's a real idea, it really is in part "let's make up stuff for it based on what we propose it to be" based on existing rules, and given that one has to choose which existing rule(s) to follow vs knowingly violate. DMacks (talk) 07:46, 11 January 2011 (UTC)[reply]
I have read it, but it does not discuss my questions? There are some verified discoveries which breaks or contradicts scientific paradigms, such as the heavy proton recently observed. --Plasmic Physics (talk) 09:04, 11 January 2011 (UTC)[reply]
The problem with calling it negative matter is that you do not specify which property is negative (for example, electrons are negative matter because they have negative charge or would it be better to call the positron "negative"?). If you do mean negative mass, then no, this could not be dark matter because this is known to have positive mass. It is interesting to speculate, but, as far as I know, no exotic particles have ever been discovered that exhibit any of the properties expected of negative mass. Our best guess at the moment is that negative mass does not exist, but at one time it was believed that antimatter wouldn't exist, so who knows what will be discovered in the future? An antiproton is indeed made of antiquarks, and is a negative proton in the charge sense, but it has positive mass equal to that of the positive proton. Current theories of supersymmetry do not include any particles with negative mass. Dbfirs09:49, 11 January 2011 (UTC)[reply]
Chevrolet Volt heater operation
A typical gasoline engine car provides no heat for the first several minutes/miles of operation, until the engine is hot and the thermostat opens. I've heard that some cars of the 1940's and 1950's had additionally a gasoline-burning heater which provided instant heat, which would be highly pleasing in the northern US in the winter. My question is, does the Chevy Volt heat the passenger compartment only with waste heat from the gasoline engine, or does it provide instant electric resistance heat? If so, does it also use waste heat from the gasoline engine to heat the passenger compartment after the gas engine has started and warmed up after long distance driving? Instant heat would be a big selling point for those in areas where it gets extremely cold in winter. Edison (talk) 05:15, 11 January 2011 (UTC)[reply]
Yes to both[18] it uses both waste heat and electric heat. But using electric heat cuts the range significantly. Apparently this problem is one of the reasons that pure electric cars are not more common - it's very hard to store enough power to both heat the cabin (or cool it) and power the wheels. Ariel. (talk) 06:39, 11 January 2011 (UTC)[reply]
Even if the all electric range decreased significantly, it would seem like a strong selling point. A car plugged in could also be "preheated" off the grid, by a timer or by electric signalling (Tweet your car heater). I wonder if an electric block heater on a gas engine car provides heat immediately, or if it does not get the engine and coolant warm enough for that? Edison (talk) 15:33, 11 January 2011 (UTC)[reply]
You might be interested to know how the Prius handles the early heating issue: when you turn off the car, it pumps the coolant into an enormous thermos which keeps it hot for a few days! --Sean16:32, 11 January 2011 (UTC)[reply]
Is there an article or website somewhere which describes this? With gasoline engines, there is a danger of damaging the block if hot coolant is placed in a very cold engine or vice versa. Edison (talk) 20:24, 11 January 2011 (UTC)[reply]
on what basis the inversions are classified....the inversions are provided a specific number why?..
for single slider crank chain..
1.steam engine
2.whitworths mechanism
3.crank and slotted leverquick return
4.hand pump,pendulum pump
so my basic question is that why the inversions are number specific.is there any rule that says we must fix this link first and this one to be fixed second.
dplease help me —Preceding unsigned comment added by 115.248.161.154 (talk) 05:20, 11 January 2011 (UTC)[reply]
Electric utilities are generally required to limit the amount of high speed recurring voltage variation so that the lights do not "flicker" noticeably due to industrial operations such as motor starting or arc furnaces at some other customer. This often has required putting in much heavier power supplies than would otherwise be required, at a cost of millions of dollars. "My friend flicker". Edison (talk) 15:37, 11 January 2011 (UTC)[reply]
Flickering flame is a form of combustion instability. Mechanical and aerospace engineers study flame stability in the design of combustion engines (including automobiles engines, jet engines, and rocket motors). Controlling "flicker" may involve careful timing of fuel injection, valve control, and mechanical design of the combustion chamber. Nimur (talk) 19:29, 11 January 2011 (UTC)[reply]
Hi, several times I have found when I place a book (or road map etc) on the front passenger floor, I get condensation, enough to leave significant water damage on the book. It seems to mainly happen when I have the aircon on, but I think it has happened at other times too. I'm more careful these days with books, but it seems to still happen on the carpet, although it is less noticeable then, perhaps because it doesn't accumulate. Does it mean I have a leak, or is it just something that happens to cars? It's been emotional (talk) 06:43, 11 January 2011 (UTC)[reply]
I know that on many Jeep Wrangler models, the drain for the air conditioner goes through the firewall of the vehicle on the passenger side. This drain often becomes clogged and the water will then spill over into the cabin by the passenger side foot well. If you open the hood and look for a small tube coming out of the firewall on that side of the vehicle, you should be able to see it and clear it. See this link for an example of what I'm talking about. Or there is water coming in from the engine cowl. See this link for more on that. Note: I'm familiar with Jeeps, so both links are to a Jeep forum that I'm familiar with. You didn't mention what kind of car you have or if you drive a Jeep, so your mileage may vary. :-) Dismas|(talk)08:06, 11 January 2011 (UTC)[reply]
It could be condensation on the airconditioning pipe that feeds cold air to the footwell dripping down onto the carpet. I vaguely recall someone I know who had a car that actually DRIPPED water slowly onto the carpet when the aircon was run. Can't remember the car, whether or not it was old or new or had a known problem etc. Zunaid12:04, 11 January 2011 (UTC)[reply]
Can we collect nectar collected by the bees before it becomes honey? Will it taste like, say, maple syrup?
On the other hand, can we use natural or artificial enzyme to process collected nectar? Is it possible to "brew" honey in a factory? Let's say we may build a man-made beehive with a built-in nectar collector. Then we collect the nectar from the beehive and let the poor bees work day by day without getting anything. We can "brew" honey using the high-tech regurgitation vessel.
I just finished watching Bee Movie the third time. This movie gives me some kind of desire to control the nature and enslave the animals and destroy small farmers. -- Toytoy (talk) 08:34, 11 January 2011 (UTC)[reply]
Yes, but the average honey bee will make only one twelfth of a teaspoon of honey in its lifetime and I doubt whether a human could do the work much faster. The nectar tastes of the flower from which it is collected. You can drink the nectar from clover flowers quite easily, but in minute quantities.--Shantavira|feed me09:48, 11 January 2011 (UTC)[reply]
Where do you get the 1/12 of a teaspoon per bee-life from please? I've heard that before, I'd like to check its validity, as I'm awed that a teaspoon of honey is the life's work of twelve bees. 92.24.190.219 (talk) 21:28, 11 January 2011 (UTC)[reply]
I think the fuschia has a lot of nectar because it's pollinated by hummingbirds. (This fact, coupled with the absence of any British hummingbirds, only increases the puzzlement I expressed in that thread. Will have to look out for insects on fuschias ... maybe a butterfly with a long tongue could get at the nectar.) 81.131.11.15 (talk) 15:24, 11 January 2011 (UTC)[reply]
Fuchsias (note spelling) are not native to Britain; they are (or originally were) imported, propagated artificially by nurserymen and gardeners, and probably never get pollinated naturally in Britain (although it's just possible that some hawk moths, such as the Elephant hawk moth whose caterpillars will apparently eat fuchsias, might adapt themselves to some varieties of the plant. 87.81.230.195 (talk) 16:42, 11 January 2011 (UTC)[reply]
What puzzles me is that I like to rob their nectar myself, which worked great in the cold north of the country in my childhood, but I never seem to get any these days, so something else must be getting there first, but what? Like you say, maybe it's hawk moths depriving me of what's rightfully mine. I've consciously noted the spelling before, it doesn't help. 213.122.45.159 (talk) 17:19, 11 January 2011 (UTC)[reply]
I had a similar objection to those sorts of redirects years ago when I first arrived at WP. But I got over it. We have to deal with the fact that vast numbers of people say "few-she-ah", not having the slightest idea, and even less care, that it was named after anyone calld Fuchs, and if they were to be so advised, they'd still in most cases avoid "fooks-ia", partly because it sounds quasi-rude and partly because nobody else they know ever calls it that, and they don't want to be the odd man/woman out. This is a good example of what I call the Schnitzel Syndrome. People tend to say "snitzel", or worse, "snitchel" - and then spell the word to conform to their mispronunciation. The world is full of people with tin ears when it comes to anything that's even slightly out of the ordinary for their idiolect, and for those who do hear the differences, it can be very unsafe to risk appearing pretentious. -- Jack of Oz[your turn]19:03, 11 January 2011 (UTC)[reply]
To complicate matters, I imagine many people hear of it as a color name first. While 'fooks-ia' can be argued as correct pronunciation of a (latin-ish) scientific name, I'm not sure this applies to the color. Also, my copy of the (descriptivist-leaning) NODE gives /ˈfyoō sh ə/ as the only pronunciation for the color and plant. SemanticMantis (talk) 20:01, 11 January 2011 (UTC)[reply]
I understand your question is somewhat tongue-in-cheek, but the whole point of eating honey is that the bees do all the 'leg-work', and we get a delicious treat with a long shelf life. I don't think you'll find a way to harvest nectar that is more efficient or less costly. SemanticMantis (talk) 20:05, 11 January 2011 (UTC)[reply]
Anyone with new ideas for theories in creation of solar system
I am A. Mohammadzade, and I live in Iran, and graduated in Iran University of Science and Technology. I have some studies in astronomy and physics thus, I want to have scientific discussions about my favourite course, without political or religion based matters.
I wrote some letters to physicists and scientific researchers, to send my new idea to them. In these contacts, I learned some knowledges, and will use them for further researches.
I named my theory "Great Cojunction" which, is based on the new observations in astronomy. I want to publish that.
As we know, the explaining of world creation guides us to two parts of observations:
Are there such as our solar sytem in other places and galaxies?
Are there some universes same to our one?
I think that is not correct that we say something about God and creation when we have so shortages in our theories and calculations, and I try to find out that our solar system is special one.
Finally, I say it is so.
First, I wrote some questions to them about the shortages in recent theories of Big Bang and solar system mechanism, such as this (that I copy from my letters):
Some questions:
If the matter and space in 0.0001 second of Big Bang expanded in the radius of solar system, then the first hadrons might have 1000c speed, because the light moves this radius in time about 1000 seconds. If hadrons were 10 to the power of 14 degrees centigrade hot, then all nuclei of atoms might have such tempreature now. Cand we use thermodynamic rules for first hadrons or quasars?
And for the solar system:
Otherquestions:
How can invisible fine particle orbit in any orbital around the Sun?
The cloud in density, 3 atoms or 100 atoms in one cubic centimeter can be visible? We live in ocean of atoms of air 1 milion atoms in one cubic centimeter and it is not visible.
What made the center of earth 6000 degrees centigrade? Can condensing make this heat, and it still be warm for 4 billion years?
Where did made the water?
Why Phobos is not spiral and Icarus has such orbital?
What made Titan so seemed to Earth?
What made heavy metals and elements in Earth?
What made Cassini discontinue in Saturn?
What made the sun spots?
How did the fine particles condense together?
Smallest moon of Mercury, Fubus has more density than semi-star Jupiter, why?
Why the orbital of Pluto has so angle with orbital of other planets?
The coma of comets move ahead of that and has about 150 million kilometers length with any core.
Less than moon, which gravity formula can display thus movement?
My remarks are these. And I hope that I be sucsessful to publish them and and day write them here. Thoses problems in desription are not for my less knowledge about the solar system, those are some real undiscript subjects in recent theories, I hope to solve.—Preceding unsigned comment added by 78.38.28.3 (talk) 10:00, 11 January 2011 (UTC)[reply]
I've tried to understand your questions as best as possible. Your English isn't always very understandabale but that isn't a problem. Here are some answers:
I didn't understand this question
Nebulae are visible because the gasses absorb light from stars then re-emit them, some in the direction of earth. We can see them because of the light they re-emit and because they are against a background of black space. Air in Earth's lower atmosphere is not excited by radiation in the same way and we look through it to a background of tress mountains, whatever is in the way, not against empty black space, thus we do not see this effect. For something similar on earth see aurora (astronomy).
Phobos is a captured asteroid rather than a moon that was formed at the same time as Mars. You'll need some understanding of orbital mechanics to understand why the orbit is the shape it is (or someone with more knowledge will come along to explain). Same with Icarus.
In which way do you mean Titan is similar to Earth?
All the heavy metals (heavier than oxygen) are created in supernovas when VERY massive stars die and explode, which scatters the elements all throughout the universe. See supernova nucleosynthesis.
You mean "smallest moon of Mars". Phobos is composed of mostly rock. Jupiter is composed of mostly gas. In fact all the rocky planets are denser than the gas giants.
Much of the guts of the question is beyond me. But the header grabbed my attention, reminding me of what King Alfonso X The Wise of Galicia, Castile and Léon, said:
Had I been present at the creation, I would have given some useful hints for the better ordering of the universe.
Thank you for correcting my remarks and for your replies. I ought to explain some of my questions. The gravity roles for all objects in universe is so that we have for planets and stars. I say that is there any formula for particls and icy matters in density less than gas in coma of comet that tide them togather in such distance 150 - 800 million kilometers?
I know how the elements are made in supernovas thus, I think that if chondrites brought them here to our Earth, then they might be equal part of them in all over the earth, but we have so mines in parts of Earth: iron, copper, gold, and aluminum. So, what made the asteroids? Why such asteroids are not near the outer planets? Where did the temprture of Earth's core come from? If chondrites made the planets so the Jupiter, Sun, Saturn, and Uranus had more density, that observed that Earth is 4.5 billion years old, but the rocks of Moon are 3.5 billion years old? The Titan has atmosphere only nothing, no life condition and else other, I say: what happened that the Pluto lie in such orbital and else others?
I have good replies to these questions based on my developed theory development of the solar system mechanism theories by Coiper and Whitsicher. Best regards. —Preceding unsigned comment added by 78.38.28.3 (talk) 04:24, 12 January 2011
Black holes and big bangs
Last night on a TV show called Into the Universe with Stephen Hawking Dr. Michio Kaku said the mathematical models for black holes and those for the big bang are very similar. "Similar" is a subjective word, and if I saw the models on paper next to each other, the best I could do is look at them as pictures. So I wonder out loud to any of you who have more understanding of the two models, how similar are they really? 20.137.18.50 (talk) 13:38, 11 January 2011 (UTC)[reply]
This is perhaps not a very helpful answer, but they have in common the fact that they are singularities, we can't see or measure anything in them, and we don't understand them. I'm sure an expert can give a much more useful and informed answer. Dbfirs16:51, 11 January 2011 (UTC)[reply]
Roger Penrose has pointed out that a black hole and the big bang are fundamentally different in that in a black hole there are tidal effects that increase towards infinity as you come near the singularity, whereas there is not supposed to have been any tidal effects close to the big bang singularity. –Henning Makholm (talk) 19:52, 11 January 2011 (UTC)[reply]
Prison nutrition and strength training
(I guess this is a science question. Maybe it could be a humanities question too.) It is part of legend that incarcerated hoodlums spend their time lifting weights, such that they leave the penitentiary much bigger and stronger - and therefore more dangerous - than they entered it. But considering the restrictions of prison life, how is this nutritionally possible? Wouldn't it require a lot of protein-rich food to build up large muscles? Would not an inmate, in order to acquire and maintain such a physique, require a much richer diet than his sedentary fellows? How would he acquire the calories? By bartering with other prisoners? Or is penal alimentation handled in such a way that prisoners can decide for themselves how much they will eat? LANTZYTALK13:41, 11 January 2011 (UTC)[reply]
I assume many a skinnier inmate's lunch is stolen by, er, given to a guy who starts out bigger and/or meaner who gets bigger, thus forming a cycle. 20.137.18.50 (talk) 14:22, 11 January 2011 (UTC)[reply]
There is an over-supply of protein in most Western diets. Adults eat far more protein than they need, and the surplus is normally just converted to calories. 92.24.181.78 (talk) 15:19, 11 January 2011 (UTC)[reply]
They aren't fed gruel. They're fed what is basically cafeteria food. Googling "prison food" comes up with many articles describes common practices in the US. It doesn't sound hard to get enough calories or protein. All-you-can-eat buffet style seems common for certain categories of food (e.g. potatoes, beans, etc.). --Mr.98 (talk) 16:52, 11 January 2011 (UTC)[reply]
Nutraloaf discusses just where US courts have considered the edge of "adequately nutritious" to be. There's not enough information there, or enough of a standard, to gauge whether that has enough protein to allow for much muscle building. -- Finlay McWalter ☻ Talk21:21, 11 January 2011 (UTC)[reply]
In unconventional prisons operated by the United States federal government, including those operated to detain enemy combatants, "dietary manipulation" enhanced interrogation techniques (feeding prisoners nothing but Ensure drink) is considered acceptable and legal. "“This technique involves the substitution of commercial liquid meal replacements for normal food, presenting detainees with a bland, unappetizing, but nutritionally complete diet. ... “Although we do not equate a person who voluntarily enters a weight-loss program with a detainee subjected to dietary manipulation as an interrogation technique, we believe that it is relevant that several commercial weight-loss programs available in the United States involve similar or even greater reductions in caloric intake.”" Nimur (talk) 22:08, 11 January 2011 (UTC)[reply]
In "unconventional prisons operated by the US federal government", plain old torture is also used, both officially and unofficially. As we now know, neither the eights amendment nor basic human rights or decency count anything if the Shrub in the White House determines that somebody is an "enemy combatant" (no matter if that is true or not). --Stephan Schulz (talk) 02:21, 12 January 2011 (UTC)[reply]
After a cursory read of some of the references at Nutraloaf, it does not appear that any of the prisoner suits attempted to challenge the nutritional value of the food, so they don't really tell where courts would draw the nutritional line, were that question before them. As for Nimur's links, those who defend such techniques also seem to argue in general that the constitutional protections afforded domestic criminals do not apply to WoT detainees at all, so we cannot really infer anything about what they think about the effects of the 8th amendment when it does apply ... –Henning Makholm (talk) 22:37, 11 January 2011 (UTC)[reply]
I do believe that the original genesis of the US RDA (recommended daily allowance) of essential vitamins and trace minerals was the definition of the amount of such nutrients required to prevent disease in federal prisoners. Franamax (talk) 01:24, 12 January 2011 (UTC)[reply]
In a letter to Flex (Flex 28.10 (Dec 2010): p32(1).) a body-building inmate in Alaska's prison system states that he has access to as much whole food and protein as he wants and that he eats 5-6 meals a day. He adds that he has put on 30 lbs of muscle since the beginning of his incarceration. While anecdotal, this suggests that at least some of the US's prison population has access to additional nutrician if they need it to support a body building program. Cla68 (talk) 05:10, 12 January 2011 (UTC)[reply]
Excitation of electron
A photon interacts with an electron in an atom which excites the electron causing it to jump to a higher energy level. but what happens to that particular photon involved in the process. I mean a photon is a particle and it doesn't makes sense for it to just go poof! -Raky rough (talk) 14:33, 11 January 2011 (UTC)[reply]
Well sometimes it is useful to think of photons as particles, and at other times it is clearer to think of them as waves that can be generated or absorbed by electrons or in many other situations. See Photon#Stimulated_and_spontaneous_emission and Absorption_(electromagnetic_radiation) for some examples. Remember that the photon as a particle has zero rest-mass (all of its apparent mass is "really" just energy), so it can appear and disappear as energy levels change. You say "particular photon", but they are actually indistinguishable because they can all be considered as just "packets of energy". Dbfirs17:22, 11 January 2011 (UTC)[reply]
Richard Feynman compared the absorption and emission of photons to an acoustic wave (as a metaphor only - don't try to read too deeply into this). Here's his explanation in The Pleasure of Finding Things Out... "The view is that photon numbers aren't conserved, they're just created by the motion of the electron." Then Feynman makes an analogy of emitting and absorbing photons as a comparison to a person speaking or hearing words. There's no "word bag" that runs out of the word "cat" if you say it too often, or don't hear/absorb enough words. You aren't conserving the count of the words - the words only exist as a phenomenon of interaction when you speak or hear something. Similarly, photons only exist as a "phenomenon" that exchanges energy and momentum when matter undergoes an electromagnetic interaction. Nimur (talk) 19:36, 11 January 2011 (UTC)[reply]
Actually, photons aren't just packets of energy - they also have a certain fixed angular momentum (irrespective of wavelength, interestingly enough). This angular momentum is what allows the electron to jump up the energy level; it is also experimentally detectable as a force applied by circularly polarized light. (See also here) Wnt (talk) 06:09, 12 January 2011 (UTC)[reply]
I think it is a lantana variety. I am going by the way the outer flowers are opening first and the shape of the leaves. There are many varieties so a better photograph is required to get a better identification Richard Avery (talk) 18:20, 11 January 2011 (UTC)[reply]
Lantanas are very common around here (I live about 20 miles from Fremont BART), so that's a reasonable suggestion, but although I'm quite familiar with what they look like, that picture is just too fuzzy for me. Looie496 (talk) 19:47, 11 January 2011 (UTC)[reply]
Hmmm, by the way... Is any of the fancy software for sharpening images from ground-based telescopes usable on photos like this, and is it freely available? Wnt (talk) 06:11, 12 January 2011 (UTC)[reply]
No, the air pressure (and thus the density) is equal at all points inside the bubble, in the simplest approximation. Insofar as you can consider a bubble in "equilibrium", the gas pressure is uniform at all points in the bubble, and is equal to the surface-pressure exerted on the interior of the liquid bubble surface (that is, the sum of atmospheric pressure plus the surface pressure of the liquid, related to its surface tension). In a more detailed, dynamic and time-varying analysis, the pressure at each (x,y,z) point in the bubble varies with time and satisfies an acoustic wavewave equation, with boundary conditions defined by the liquid-gas interaction at the surface. The actual bubble surface will "wobble" dynamically, varying in shape around the approximately spherical "steady state" eigensolution (which is only satisfied when the pressure is exactly uniform at all points in the bubble). Other effects you might consider include: whether the bubble is moving as a whole entity (and potentially undergoing force due to net acceleration of the entire unit); the force of gravity, which does set up a vertical pressure gradient in the bubble (mostly insignificant for small bubbles in normal atmospheres); and anything the bubble edge bumps into (such as a liquid surface, another bubble, the ground, and so on). Nimur (talk) 19:23, 11 January 2011 (UTC)[reply]
A soap bubble in air is interesting, because to first approximation it is very simple, but as you point out, the details quickly become complicated. The dynamics seem to be very neutral, and thus the familiar 'wobble'. Do we have any articles that discuss neutral stability (or perhaps more precisely neutrally stable equilibria)? Surprisingly, the word 'neutral' does not occur in stability theory, dynamical system, or even equilibrium. Linear dynamical system does have 'centers' listed on the classification diagram, but no definition or discussion (and this is obviously not a linear system anyway). Is there some terminology I'm missing? SemanticMantis (talk) 19:50, 11 January 2011 (UTC)[reply]
You might be looking for information contained in the perturbation theory article? The "neutral equilibrium" is properly called an eigenfunction - specifically, it is the 0th order, or zero-frequency, solution of the acoustic wave equation with boundary conditions applied. It may also be called the "trivial solution," the "steady state solution", and so forth. The wobbles would be other higher-order harmonic eigenfunctions; it so happens that in this case, these solutions are oscillatory, so the bubble "wobbles" back and forth. I think the message we need to convey to the original poster is that the actual answer depends on how accurately and completely you want to analyze the bubble. Nimur (talk) 20:02, 11 January 2011 (UTC)[reply]
Now that you mention it, as "accurately and completely" as presently possible. I made the mistake of assuming that is how all questions are answered here. —Preceding unsigned comment added by 165.212.189.187 (talk) 21:19, 11 January 2011 (UTC)[reply]
Well, I could dive deeper into a presentation of the wave equation solution, if you are interested in the complete "answer" to this question; but I somewhat hold the opinion that either (a) you already understand techniques for solving partial differential equations, and can easily apply them to analytically or numerically solve for soap dynamic pressures; or (b) you do not already know how to solve those types of equation, and even if I provided a flawless overview of them here, the brief few paragraphs I might write would be insufficient preparation to train you in how to apply those mathematics to this problem. (I'm sure you're capable of learning them, if you're interested to learn; it's just that this is a complicated subject and takes a long time to master). Are you interested in books on soap bubble dynamics? Many prestigious physicists have written extensively on the topic of soap bubble physics; in fact, entire textbooks exist to explore their dynamic solutions. Here are a few Google search results to peruse; those will expose you to some of the techniques you need to analyze the problem "as accurately and completely as presently possible." If you need help finding a more specific resource, I can recommend numerous fantastic textbooks on mathematical methods and/or mechanical dynamics. Nimur (talk) 21:45, 11 January 2011 (UTC)[reply]
We have an decent article on the Fuller projection, which has a couple of nice examples of it. What I can't find anywhere on the web (and this would seem like an obvious thing that people would like to produce as a project) is a nice black-and-white outline version, such as you could easily print out and copy, colour in, cut out, and assemble. I'm quite prepared to add the tabs myself, but my graphic design skills fall sadly short of converting the thing to a simple, clean, outline version.
So, does anyone know of such a source, or feel generous enough to make one? I'm sure such a thing would be heavily linked-to and used in all manner of schools and clubs, so you'd be contributing to the global education of at least one generation! 86.163.214.50 (talk) 21:40, 11 January 2011 (UTC)[reply]
Fortunately, this map is an SVG file. You only need remove the 1st, 3rd, and 4th path groups (enclosed in <g> tags) to reveal only the continent outlines. I have uploaded a modified version, File:Fuller projection rotated (land only).svg. You should be able to save this as a PNG or other file; or print it directly. If you need the dashed-lines, or want any color or line-thickness changes, those are easy modifications. Please abide by the license if you reuse this image. (If you aren't sure how to use this file, click here for a version without grids and with grids). Nimur (talk) 22:53, 11 January 2011 (UTC)[reply]
Oh wow, thank you so much! And yes, I'll abide by the license. It will be quite cool to tell them they're using something a volunteer made just so people could see it and use it :) 86.163.214.50 (talk) 00:32, 12 January 2011 (UTC)[reply]
Glad to help. Technically it is the work of many volunteers. The source dataset came from the National Geophysical Data Center (funded by the United States federal government); the original image was created by Eric Gaba, and all I did was remove the colors... It's a collaborative effort to keep information free and free. Nimur (talk) 00:51, 12 January 2011 (UTC)[reply]
January 12
Obesity and diabetes caused by low carb diet?
There are so many more obese people in North America compared to Europe that you can instantly see the difference on the streets. Also, when I'm in the US or Canada, I have difficulties getting my usual high carb, low fat diet. If you order steak with potatoes, what you get is a huge steak and hardly any potatoes. Ham sandwich for lunch? You'll get a lot of ham, hardly any sandwich, like this. Apparently, this is the normal North-American diet, they get most of the calories from fat, proteins, and eat very little carbohydrates. Also, people there seem to think that carbohydrates are bad. After first ordering for more potatoes, I only got what I was served the first time, so I asked for a plate full of potatoes. The (very obese) waiter almost refused to give me that. He said that it is very unhealthy to eat that many potatoes, even though one plate full would still be half of what I normally eat. After finishing that plate I ordered another plate. The waiter almost went crazy...
This leads me to think that a normal high carb diet can prevent obesity and diabetes. Perhaps people in North America are obese because they believe that carbs are to blame for obesity. So, the less carbs they eat, the fatter they become, prompting them to eat even less carbs. This makes sense, because a low carb diet will give you very little energy to be physically active. Energy from fat cannot be released rapidly enough to sustain activities like fast running for long... Count Iblis (talk) 00:54, 12 January 2011 (UTC)[reply]
Wow - I had exactly the opposite observation - that people in the US eat way too many carbs, and not enough fats, and that is causing the obesity. (Since fats make you feel full.) I think you just had a weird waiter. Also Americans eat a lot of cereal (breakfast cereal). Ariel. (talk) 02:10, 12 January 2011 (UTC)[reply]
The phrase "Standard American Diet" (a somewhat derogatory term) is sometimes used to refer to a diet that is both high in fats and high in processed sugars (e.g. cola, candy, added sugar). It is correlated with various diseases and obesity. Overall though, the more important predictor of obesity is chronic overeating, i.e. eating more calories than your body actually needs. Some foods, including both fatty foods and high carbohydrate foods, have a high level of Calories per unit volume, which can make them easier to overeat (as compared to most fruits and vegetables, for example). However, that's certainly not the only factor. Cultural factors, such as a preference for snacking and large portions, also contribute to overeating. At the same time there is a lot of contradictory diet advice. For example, the Atkins diet (a rather popular fad diet in American a few years ago) recommended that people would best lose weight on a diet very low in carbs and high in fats. On the other hand, the food guide pyramid and other standard advice tends to recommend a low-fat diet with carbohydrates as the dominant base. Dragons flight (talk) 02:38, 12 January 2011 (UTC)[reply]
The matter is almost certainly too complex to be reduced to a three-way fat/protein/carbohydrate split, let alone to a hypothesis that any of the extremes in that simplified continuum is ideal. Each of the three groups contains wild variability in digestability, metabolism and biologic utilization. For example, there is a huge difference between how a given amount of "carbohydrates" affect the metabolic regulation when eaten as readily-dissolved simple sugars, or as slowly digested long-chain starchy food.
The energy breakdown also says nothing about fiber, or any of a long list of trace nutrients, or even currently-assumed-irrelevant compounds that have yet undiscovered effects on appetite regulation and metabolic signalling. –Henning Makholm (talk) 02:53, 12 January 2011 (UTC)[reply]
http://equalitytrust.org says it's due to income inequality: people who don't know how they will make their next housing or heating payment are more likely to overeat from the abundant subsidized high calorie food sources available in the US. 71.198.176.22 (talk) 06:41, 12 January 2011 (UTC)[reply]
Something aliens do on TV that I wonder if it's true
I saw a Doctor Who episode where aliens made all the TV channels, radios, and phones broadcast specific message and I'm wondering if this is real or fiction. I've noticed that things like iPhones (especially original ("2G")) causes radio frequency interference when it gets near speakers where the speakers buzz and such. So I'm wondering about the idea of something that causes that kind of interference that you point it at a speaker but instead of just random noise, it'll send out say music and the speaker plays music. I'm not talking about jamming radio signals as on TV/radio as that's been done before, but where any speaker will pick the sound up as long as it's not shielded and has power to it. Geoffry Nathan (talk) 02:54, 12 January 2011 (UTC)[reply]
It is quite possible to get a simple radio to broadcast a message accross a broad range of frequencies. If you've ever been VERY close to a transmitter, you will sometimes find that the station being transmitted will "bleed" through and show up over the entire dial. What basically happens is that a very high powered signal will bypass the tuning circuit and just drive the radio by itself. The principle is actually explained here, which describes how to build a working AM radio receiver without a tuning circuit or even an external power source. --Jayron3203:25, 12 January 2011 (UTC)[reply]
You can broadcast all frequencies at once, but it won't work. AM has one modulation scheme, FM another, cordless phones a couple more (some digital some analog), TV also has video, and cell phones are packet based and you couldn't send to all at once even if you wanted to. And then you have PAL vs NTSC differences for TV, and the same frequencies in different parts of the world is used by different devices, and basically you have to individually target each type of receiver. Ariel. (talk) 04:35, 12 January 2011 (UTC)[reply]
Sure - just being able to travel the galaxy isn't really that hard if you have time to space - photons do it all the time, and they're not very smart. Radio is radio, there is no reason to think aliens have any special abilities with it. If they want to target all receivers they'd need to design for each type. Ariel. (talk) 06:51, 12 January 2011 (UTC)[reply]
Dismas's point aside, it is perfectly possible to broadcast a signal so powerful that you can essentially bypass the tuner of a radio and cause the signal to "appear" to be coming from all frequencies. This works equally well for FM receivers as AM receivers (you'd need to broadcasting both FM and AM signals to be picked up by both). My cheap clock radio which plays the local FM country station at all frequencies (said tower is about 3 miles from my house) will attest to that. Analog TV signals are an order of magnitude more complicated than radio, but in principle if you use the correct standards you should be able to hijack it in much the same method (i.e. broadcasting a powerful enough TV signal, correctly coded, could possibly bypass the tuner circuit as well). With Digital TV, such methods likely wouldn't work, neither with Cable, so we'd have to fall back on "Any species intelligent enough to traverse interstellar space could figure out how to do it" response. --Jayron3204:59, 12 January 2011 (UTC)[reply]
Or the Sperm whale... Once I was out strolling when I laid myself to rest in a big field of tall grass... Sorry, had an Eric Burdon moment there. Anyhoo, yeah, it looks like the Sperm Whale's brain is bigger than the blue. --Jayron3206:03, 12 January 2011 (UTC)[reply]
The article elastomer has some examples of such substances. Different types of caulk will have different ingredients; is this silicone caulk, acrylic caulk, and what specific brand and type of caulk is it? --Jayron3205:59, 12 January 2011 (UTC)[reply]
viral inactivation in hpv blood
describe the neat skecth of viral inactivation in hv blood?with following flow chart?
describe the neat skecth of viral inactivation in hv blood?with following flow chart? —Preceding unsigned comment added by 202.67.226.236 (talk) 06:15, 12 January 2011 (UTC)[reply]
Welcome to the Wikipedia Reference Desk. Your question appears to be a homework question. I apologize if this is a misinterpretation, but it is our aim here not to do people's homework for them, but to merely aid them in doing it themselves. Letting someone else do your homework does not help you learn nearly as much as doing it yourself. Please attempt to solve the problem or answer the question yourself first. If you need help with a specific part of your homework, feel free to tell us where you are stuck and ask for help. If you need help grasping the concept of a problem, by all means let us know.--Jayron3206:20, 12 January 2011 (UTC)[reply]
Resolved
Please do your own homework.
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