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.
Is there an estimate available for the fraction of the Earth's mass that is dark matter?
Also, what about the fraction of stars made of dark matter? If a hefty fraction, wouldn't it greatly change the way stars work? Thanks, Rich Peterson24.7.28.186 (talk) 05:17, 21 June 2011 (UTC)[reply]
Although the total mass of dark matter is estimated to be nearly five times as much as the mass of normal matter in the universe, most of it is thought to exist outside planets and stars. I suppose it is a matter of opinion whether the billions of neutrinos passing through the earth make up part of the earth's mass, but I think it would be a very small proportion. Perhaps an expert can make a calculation? Dbfirs06:21, 21 June 2011 (UTC)[reply]
Not that rare. But read dark star for an interesting speculative possibility that dark matter played an important role on the behavior of the very first stars of the universe. The OP's instinct that dark matter might change the way stars work is correct for these stars (If they turn out to actually exist). Dark matter plays little role on the behavior of regular stars like the sun. Dauto (talk) 07:06, 21 June 2011 (UTC)[reply]
I was under the impression that the phrase "dark matter" is simply a term used as a catch-all label for "that which we cannot observe/identify/explain" much like "terra incognita" was used on old maps. Roger (talk) 07:19, 21 June 2011 (UTC)[reply]
Whilst the term was invented for this "missing mass" we didn't know anything about, since significant research has been done it's more like a known unknown. 'Dark' is a useful word because it implies we can't observe it, or at least technology-wise, it is difficult to directly observe. There are other 'dark' things theorised, Dark energy, Dark fluid and Dark flow for example. Since we have little idea of what dark matter actually is, then it may well have more than one constituent part, so 'dark matter' can be consider a grouping of sorts, but it seems to be a useful and well defined one. Grandiose(me, talk, contribs) 07:25, 21 June 2011 (UTC)[reply]
Here I get a density of 0.3–0.39 GeV/cm3. Multiplied by the volume of the Earth that's 2–3 kg, or 3–4 million kg in the volume of the Sun. In either case, that's about one part per septillion. It would be a bit odd to include that mass in the "composition" of the Earth/Sun, because the dark matter is a gas of rapidly moving, barely-interacting particles (like neutrinos, which are one component of it), and there just happens to be that much of it passing through the Earth/Sun at any given time. -- BenRG (talk) 08:19, 21 June 2011 (UTC)[reply]
The content of the link reads "Error 404 - Not Found". Do you need a login there?
Dark matter is subject to gravitation, so one would expect it to aggregate inside stars and planets. With this, it should be possible to calculate some limits on its temperature (the stuff (to avoid the word "particle") would have to be faster than the escape velocity, and with some nifty observations it should be possible to calculate a lower limit for the interaction probability dart to normal matter and dark to dark matter, too, but I havn't seen anything yet. 5BYv8cUJ (talk) 11:52, 21 June 2011 (UTC)[reply]
Unlike ordinary matter, dark matter cannot cool (radiatively), therefore it is not expected to aggregate, at least not to anything like the density contrast represented by stars and planets. Dark matter is distributed like a tenuous gas with very little, if any, self-interaction. --Wrongfilter (talk) 14:14, 21 June 2011 (UTC)[reply]
I'm not thinking of density but of gravitation. The article linked states a speed of 300km/s, this is far less than the escape velocity of the sun, so the dark matter would be trapped in the gravity well. With ever so small interactions it would start to aggregate. Might well be the aggregation is too small to detect, but from the principle I don't see what's wrong with that. 5BYv8cUJ (talk) 14:52, 21 June 2011 (UTC)[reply]
Thank you. And I see that as long as the results are negative they won't appear in the headlines, and so people like me wouldn't notice this sort of research at all. 5BYv8cUJ (talk) 15:31, 21 June 2011 (UTC)[reply]
Any average particle speed like 300km/s is given at infinity, where the escape velocity is zero. The particles will speed up as they approach a gravitating object and slow down as they leave, always exceeding the local escape velocity. Some kind of dissipative interaction (i.e., friction) is always necessary for capture. Frictional effects on dark matter are small but nonzero, so some capture is expected, but not a lot. -- BenRG (talk) 20:36, 21 June 2011 (UTC)[reply]
I see your point. A particle moving at 300km/s (not really matter what direction) would be accelerated towards a gravity well and thus gain more speed to overcome the escape velocity. Are there any mathematical models that account for that? 5BYv8cUJ (talk) 20:54, 21 June 2011 (UTC)[reply]
I'm not sure I understand your question, but in the absence of friction the particle's speed at a point x will be where is the speed at infinity and is the escape velocity at the point x. This is because the total energy is constant and . The "escape velocity of the Sun" is the escape velocity at the Sun's surface. -- BenRG (talk) 03:49, 22 June 2011 (UTC)[reply]
As Dauto points out, this is a standard problem (could be a homework problem for astrophysics students). The DM particles have some scattering cross-section for interactions with nuclei, so you can calculate the capute rate by the Earth. For the typical DM masses that one considers, these then settle in the Earth's core. They then get into thermal equilibrium with the Earth's core, which then allows you to compute the self-annihilation rate. This then yields a differential equation for the total DM content of the Earth (capture minus self annihilation is the increase per unit time). On the very long term you would then get a dynamical equilibrium between self-annihilation and capture. However, in case of the Earth that would take hunderds of billions of years (for the typical cross-sections that are assumed for DM).
The Sun captures so much more DM than the Earth, that the self annihilation signal from the Sun (in the form of neutrinos) is expected to be larger than from the Earth. Count Iblis (talk) 15:40, 21 June 2011 (UTC)[reply]
Thanks to all of you for all the thoughtful helpful discussion. Followup questions:Since dark matter does aggregate, perhaps minimally, to the extent that it forms haloes around galaxies, i'm thinking that its average velocity isn't much greater, and probably less than, the average galactic escape velocity(I think someone above also alluded to that in a link I haven't gone to yet)which is around a few hundred km/sec. But IF dark matter turned out to be neutrinos, isn't that a remarkable slowing down of the usual near lightspeed of neutrinos? Given they hardly ever collide with anything we know about, and usually elastically, wouldn't that mean some unknown inelastic collision exists? And is it possible that as neutrinos slow down, their cross section for some reason increases so that they collide with themselves? (I'm dreaming someday of a box with a pound of neutrinos inside with average speed l meter/year) Thanks again.-Rich Peterson199.33.32.40 (talk) 23:39, 21 June 2011 (UTC)[reply]
That is the difference between hot dark matter (HDM) which is made of particles traveling close to speed of light and cold dark matter (CDM) made of particles moving at much slower speeds. Neutrinos are an example of HDM. Cosmological models seem to require quite a bit of CDM in order to match the observed large scale structure of the universe. Dauto (talk) 00:33, 22 June 2011 (UTC)[reply]
Primary 5 Science
What will be the coloured water level in the tube that is inserted into a enclosed tank topped soda lime which a mouse is in it?
And explain why? — Preceding unsigned comment added by 220.255.1.83 (talk) 07:46, 21 June 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.
Also, you're obviously missing some numbers. You can't get numbers out of a calculation without first putting some numbers in. StuRat (talk) 07:58, 21 June 2011 (UTC)[reply]
Are you about 10 years old? (That's about right for Primary 5 in the Scottish education system), but this seems far harder than questions for 10 year-olds. Anyway, the mouse will breathe in oxygen and exhale (breathe out) carbon dioxide. The carbon dioxide is then absorbed by the soda water, reducing the volume of air. Assuming the coloured water is part of a manometer then the liquid will move towards the tank. You will need to know
The mouse's rate of oxygen consumption
How long the experiment is running for
From this you can calculate how much oxygen the mouse has used. Divide this by the volume of air in the tank to determine the percentage of air used, and thus the pressure drop in the tank. Assuming the other end of the the manometer is sealed, then it is simple to work out how much the coloured water will move.
If you don't know how much oxygen the mouse uses, then it can be calculated if you know its basal metabolic rate, and assume that its burning glucose.
Does anybody know where I can find an exhaustive list of Earth's atmospheric content? Specifically I have had some trouble finding information of the average content of nitric oxide aka nitrogen monoxide aka NO. Does anybody know the value or where to find it?
I havnt been able to find any 2011 news, only blog posts that refer to information of years earlier. Is there any 2011 news yet? Has it flowered, or is it male? 2.97.210.205 (talk) 12:20, 21 June 2011 (UTC)[reply]
Our article which you linked to includes information from 2010 which is not years earlier. A quick search easily finds [4] with comments from 2010 suggesting the sex is undetermined. It also suggests your best bet may be to just contact the person involved. I was suprised that they didn't just try to determine the sex genetically but from [5] and [6] it seems the Sex-determination system in date palms is only beginning to be understood. If you do contact the person involved you may want to consider suggesting they get in touch with the team studying the sex determination system in date palms as it would seem both would be interested in each other's work but it's possible they may not be aware of each other. Nil Einne (talk) 14:56, 21 June 2011 (UTC)[reply]
"Our article which you linked to includes information from 2010 which is not years earlier". Who said it wasnt? You first link links to something dated 2009. 2.101.2.152 (talk) 17:21, 21 June 2011 (UTC)[reply]
The OP said they could only find blog posts from years earlier. Since our very own article includes information from 2010, it's not clear why blog posts form years earlier are relevant. Also the link I included above includes comments from 2010 (regardless of when the blog post itself was dated) as I clearly said in my first post. Nil Einne (talk) 11:30, 22 June 2011 (UTC)[reply]
Rereading, perhaps there was some confusion. My impression when the OP said 'years earlier' was they meant several years ago. Perhaps however the OP was trying to say from previous years which would include info from 2010. If there was such confusion I apologise although I do feel this needed clarification since info from several years ago is quite different from info from 2010. In any case, I find no evidence of any info from 2011. Since the info in our article from 2010 is unsourced (and was added by an anonymous IPwho only edit those times) and the only source was have for info from 2010 so far comes from direct communication with the person involved I would again suggest this is the best course of action. It may be there is more info in Hebrew sources but I suspect if the tree had flowered it would have made it to English sources by now. Nil Einne (talk) 11:39, 22 June 2011 (UTC)[reply]
I can think of two different concepts of "alive or dead". One is that alive means having an active metabolism, the second is having the potential for having an active metabolism (when water is present, for example). 5BYv8cUJ (talk) 20:45, 21 June 2011 (UTC)[reply]
"I can think of two different concepts of 'alive or dead'. One is that alive means having an active metabolism, the second is having the potential for having an active metabolism". So Jesus only rose from the dead(1).--188.28.167.165 (talk) 10:35, 22 June 2011 (UTC)[reply]
Sometimes it can't. My calling them "dead" or "alive" probably oversimplifies things. A better way to say it would be "capable of germination" or "not". According to the Germination article, moisture is the key. It absorbs into the seed and its presence triggers various chemical reactions in the embryo that result in the beginning of germination. Other conditions are also required, of course, in order for germination to continue. There's an article called imbibition which describes, at least in general terms, how the moistening process works. ←Baseball BugsWhat's up, Doc?carrots→ 00:20, 22 June 2011 (UTC)[reply]
A very important trick is trehalose, a simple sugar which has a remarkable tendency to preserve proteins and other cellular constituents as if water were present. As water leaves and trehalose takes over, there is very little change in these components, but things become more and more solid. Essentially everything just stops, without other changes. Provided no other damage occurs, there's no reason for it not to resume as the water solvent is added back. I'm more familiar with it in animal systems, but apparently it has some important role in Arabidopsis seeds also.[7]Wnt (talk) 02:34, 22 June 2011 (UTC)[reply]
Yes (sort of) - see PMID16417738 and [8]. Trehalose helps cells survive freezing as well as desiccation, again by replacing water with something less vulnerable to change in the environment. Wnt (talk) 13:50, 22 June 2011 (UTC)[reply]
Have any retrograde orbit comets been observed? As in a comet which goes around the sun in the opposite direction that earth does within roughly 30deg of inclination of earth's orbit? I would like to clarify that I am speaking only in terms of periodic comets. Googlemeister (talk) 14:57, 21 June 2011 (UTC)[reply]
So what causes the retrograde orbits of comets when all planets and moons in the solar system, as well as the vast majority of asteroids have a standard orbit that I assume is caused by the formation of these objects from the sun? Is the material from comets not from this system? Googlemeister (talk) 19:15, 21 June 2011 (UTC)[reply]
Possibly, though quite likely complex gravitational interactions working on a comet over many millions of years, coupled with an already eccentric orbit, could alter such an orbit to do strange things. These things are literally unpredictable given the number of gravitational interactions that a comet has to contend with during its lifetime. (not just hard to calculate, but literally impossible, see n-body problem). --Jayron3220:23, 21 June 2011 (UTC)[reply]
Planets, moons and other bodies of the inner solar system were formed from a spin disk of dust. Comets come from the Oort cloud which has a separate origin. Dauto (talk) 07:31, 22 June 2011 (UTC)[reply]
Photons, when treated as a particle, are carriers of spin. You can read about spin and how it participates in atomic interactions. When a photon and an atom "interact", there is often a transfer of energy, momentum, and spin. One such interaction causes a change of the atom's spin (or, changes the spin of one or more electrons around the atom). In simple quantum interactions, the spin can only take one of two possible values; this is usually notated "up" and "down." In more complicated quantum mechanical systems, the spin can take on other values. Nimur (talk) 21:22, 21 June 2011 (UTC)[reply]
Bugonia, bee mimics
I am currently doing research for the bugonia article. One of the sources has a theory that the so-called bees were actually flies that looked remarkably similar to bees, possibly Eristalis tenax. It seems the author did not know the technical term for Batesian mimicry. So I was wondering where I could find a more comprehensive list of species meeting these critera:
looks like a bee
lays it's eggs in carrion
widespread in the ancient Mediterranean region
has a maturation time of approximately 10 days, or
has a maturation time of approximately 30 days, or
has a maturation time of approximately 10 days on a 20 day old corpse
I am not aware of any species that meets your criteria that is not a hoverfly. Many species of hoverfly are common in their ranges. However, even the ancients may have noticed that bees have four wings, whereas all dipterans have two. If you have access, you can probably find some good articles by searching for 'syrphidae' in a biological review journal, such as entomological review. There may be a few bee-looking hymenopteransaprotrophs, but I can't readily find any indication of such. SemanticMantis (talk) 22:27, 21 June 2011 (UTC)[reply]
The zoological knowledge of the ancients was very sporadic. Aristotle (c 350 BC) knew enough to distinguish between queens ("kings"), workers ("bees"), and male reproductives ("drones"), but even much later we have fellows like Aelian who thought that vipers would leave their venom on shore, swim out to sea, mate with moray eels, and then return and swallow their poison once again. So it's fully plausible that a mimic could fool at least most of the people. Craig Pemberton (talk) 00:26, 22 June 2011 (UTC)[reply]
Sure, many modern people get confused too :) Another interesting angle is that most hoverflies are good pollinators. Though they don't provide honey, I think they would generally be beneficial to a ancient Greek farms. Anyway, this practice seems like it could attract a wide variety of local hoverfly species, but I'm not sure how to easily find a list of what those specific species are. SemanticMantis (talk) 03:07, 22 June 2011 (UTC)[reply]
Am I the only one who finds it a hilarious thing that the name of the concept of finding bugs on ya is called "bugonia". --Jayron3203:42, 22 June 2011 (UTC)[reply]
I know this has been asked here before, but I want to add some things to it.
Would it be possible for both elements of a planet/moon system (probably more like a double-planet system in this case) to be capable of supporting human life? When this question was asked before, I think the asker (for lack of a better term) intended for both bodies to be more or less Earth like, but let's say the worlds were each on opposite extremes of the habitability spectrum. So the primary body would be a large terrestrial planet but still capable of supporting human life comfortably, while the smaller object would be a barely habitable Mars-sized planet with a thicker atmosphere. Probably the only way such a system could exist is through capture, or maybe through co-accretion, but then again, I'm no expert.
I guess my question then is: can a two-planet system consisting of two (relatively) large "Earthlike" planets exist naturally?
I don't see why not. Just bring Pluto and Charon (moon) into the Earth's orbit and increase their sizes a bit and you would have it. One thing that doesn't seem right, though, is a Mars-sized planet with a thick atmosphere. I would expect such a small planet to lose most of it's atmosphere to space. StuRat (talk) 00:28, 22 June 2011 (UTC)[reply]
That doesn't bother me so much, as in my scenario (yes, I'm using this for fiction as you might have guessed), the smaller body is partially terraformed. In its natural state, it was uninhabitable, much like Mars, but it was artificially brought to a minimally habitable state. 70.246.235.69 (talk) 01:30, 22 June 2011 (UTC)[reply]
Ursula Le Guin's book The Dispossessed is set in such a two planet system. I know this doesn't answer your scientific question, but it might help you artistically, to see what she did with it. Her book won several awards, and I rather enjoyed it. It could serve as a source of inspiration. Cheers. ~ Mesoderm (talk) 18:30, 22 June 2011 (UTC)[reply]
However, Mars may not have lost most of its atmosphere to space. One hypothesis is that its atmospheric gasses have mostly chemically combined with its rocks as happens continually on the Earth, but unlike the Earth it has no active plate tectonics to recycle those gasses back into the atmosphere via vulcanism. This may be because it cooled quicker than Earth by virtue of being smaller (or may be for other reasons), but proximity to a larger primary might provide sufficient energy for such a planet/satellite to maintain vulcanism through tidal friction, as with Io. {The poster formerly known as 87.81.230.195} 90.201.110.203 (talk) 01:24, 22 June 2011 (UTC)[reply]
Could two Earth-sized planets form in close proximity without coalescing? Not an expert either, but that seems rather doubtful to me. Capture seems the best bet. Clarityfiend (talk) 00:44, 22 June 2011 (UTC)[reply]
My limited understanding of the current state of theories of planetary formation (see under Nebular hypothesis) is that we don't yet know, but certainly can't rule it out. However we seem to be on the threshold of discovering enough about extrasolar planetary systems that we might soon have more definite answers. My own gut feeling as a lapsed astronomer (with friends who used to computer-model this kind of stuff) is that it's possible. {The poster formerly known as 87.81.230.195} 90.201.110.203 (talk) 02:05, 22 June 2011 (UTC)[reply]
Note they need not form together. They could form separately, and then come together - like Asteroid capture, but with a planet. Note that it need not be a gentle do-si-do. The Earth-Moon system is thought to have formed when an Earth-sized and Mars-sized planet collided. One could easily imagine two larger planetoids colliding in a slightly different fashion (with respect to orientation and velocity) resulting in two Earth-sized planets orbiting each other. -- 174.24.222.200 (talk) 17:30, 25 June 2011 (UTC)[reply]
Some factors to consider here are tidal locking and the Roche limit. The Roche limit sets the absolute restrictions to how big and how close the satellite can be. But tidal locking can be just as fatal - Pluto and Charon are tidally locked, and the Moon is tidally locked. Monthlong days and nights make ordinary biology a lot more difficult. The answer to tidal locking is to bring the moon really close so it revolves in just a single day, i.e. geosynchronous orbit. Now there are posts about this on various boards around the internet, with claims that you could have the Moon in geosynchronous orbit without breaking the Roche limit [9] but I haven't calculated this myself and I have no idea what sort of side effects would be seen beyond the mathematics (such as seismic activity from any slight variation from a perfectly circular orbit?) I think the effect on gravity on the near side of the moon would be so intense, it would be quite remarkable.
Note that the Moon reportedly could hold an atmosphere for about 100,000 years (or something like that - I see this figure on forums but I'm not finding reliable sources!), which would be more than enough for your scenario. I wonder what the surfing would be like there... Wnt (talk) 02:27, 22 June 2011 (UTC)[reply]
I'm not sure it would be dangerous or deadly. For SCUBA, at least, you are interested not in the relative proportion of oxygen, but only in the partial pressure. So if you have an atmosphere of ~200mbar pure oxygen, you should be fine (from a breathing point of view - you might have other trouble). Water boils at ~60°C at 0.2 bar, so you would not even evaporate away ;-). --Stephan Schulz (talk) 15:45, 22 June 2011 (UTC)[reply]
Agreed. See what happens in a pressured pure oxygen environment here: Apollo_1#Fire. The pressurized cabin also ensured that they couldn't open the inward opening hatch once the fire started. Whoever designed that test should have been subjected to it, IMHO. StuRat (talk) 16:22, 22 June 2011 (UTC)[reply]
The problem is, Mars has a really weak atmosphere. You can't just seed it with algae and convert all the CO2 to O2 and be done - it's just a tiny pressure, less than 1% of Earth's. I think that the pressure of pure oxygen needed is about the partial pressure of oxygen in Earth's atmosphere, i.e. about 1/5 of Earth's atmospheric pressure. Wnt (talk) 16:31, 22 June 2011 (UTC)[reply]
You are right. 200mbar of 100% O2 would work fine for an atmosphere. A StuRat mentions, it's used in some manned spacecraft (Apollo 1 had high pressure 100% O2 for takeoff, which was very dangerous and was redesigned after the fire, but would have dropped down to about 350mbars after takeoff). --Tango (talk) 17:01, 22 June 2011 (UTC)[reply]
The limit for human life (with considerable difficulty) is a partial pressure of about 65 millibars of O2. The total Martian atmosphere is about 6 millibars (at mean surface elevation). So no, the Martian atmosphere would still be much too thin to support humans even if it were 100% oxygen. Dragons flight (talk) 19:22, 22 June 2011 (UTC)[reply]
How good can the foil pan of a disposable grill conduct heat? Would it work better if it were better of worse heat conductor? Wikiweek (talk) 22:15, 21 June 2011 (UTC)[reply]
Depends on what you want. For quick, but potentially uneven heating, you want a good conductor. For slower, more even heating, a poor one. StuRat (talk) 00:33, 22 June 2011 (UTC)[reply]
I'm probably misunderstanding something, but if it was a good conductor, wouldn't there be little or no heat? I thought it was the poor conduction that caused the heat in the first place. Matt Deres (talk) 13:41, 22 June 2011 (UTC)[reply]
No, Matt is correct, the grill would be marginally more efficient if the foil were a heat insulator (place it on rock-wool or something similar to achieve this), but so much heat is generated by the charcoal that the small amount conducted away by the thin foil (to the air and whatever the foil is resting on) doesn't make a big difference, but the answer to the question is that it would work marginally better if foil were a worse conductor of heat because then there would be marginally more radiant and convected heat to cook the food. The same amount of charcoal placed in a very large and thick iron container would be noticeably less efficient because of heat conducted away from the food. Aluminium (aluminum for American readers) has a fairly high thermal conductivity but a thin sheet will not conduct very much heat away. Dbfirs19:18, 22 June 2011 (UTC)[reply]
If you have a poor thermal conductor between the flame and the food, then most of the heat will go around both and up into the air. (Since the OP said "grill", I'm assuming it's open on top, so that heat escapes.) StuRat (talk) 19:54, 22 June 2011 (UTC)[reply]
Perhaps we are talking about different designs of disposable grill. I assumed that the question was about the base pan. Dbfirs09:24, 23 June 2011 (UTC)[reply]
Irish hurricanes
Is it even possible for a hurricane to hit Ireland I know we get tail ends but is it possible for full blown tropical hurricanes to hit Ireland. The reason I ask this because of the warm current of the gulf stream should enough to keep a hurricane going. --109.78.92.74 (talk) 23:00, 21 June 2011 (UTC)[reply]
Hurricane and Gulf Stream explain why this is extremely unlikely. The Gulf Stream is only "warm" on the western side of the Atlantic relative to the deep cold of the rest of the surrounding waters. It isn't the 26.5+ degrees C that a hurricane needs. Bielle (talk) 00:25, 22 June 2011 (UTC)[reply]
The gulf stream can keep a tropical storm or hurricane going at relatively northern latitudes, such as in the case of Alex 2004. However, keep in mind a tropical cyclone generally needs waters of 81F (though there are certain exceptions) to form and sustain itself, and even then you're not going to get anything major spinning up. The gulf stream only stays so warm for so long as it heads into the far north, and even if a hurricane is moving at exceedingly fast speeds, it'll inevitably dissipate or transition into an extratropical storm before coming anywhere close to Ireland. The only shot Ireland has at claiming a Cat 1 landfall is if a dwindling TC can hold on to just enough tropical characteristics before striking the island to justify the National Hurricane Center maintaining advisories on it, but that's pretty unlikely. Juliancolton (talk) 18:09, 23 June 2011 (UTC)[reply]
Why can I see clearly when I wear two pairs of glasses?
Why can I see clearly when I wear two pairs of my own prescription glasses, one on top of the other? Shouldn't the outer pair distort the correction produced by the inner pair? I think that if a person with perfect vision wore my glasses, his own vision would be blurred. So if one pair corrects my vision, shouldn't the second pair blur it? --82.31.133.165 (talk) 23:32, 21 June 2011 (UTC)[reply]
I just tried putting my prescription sunglasses over my prescription glasses (essentially same values), and it was blurry as hell. So this would not be a general phenomenon. Looie496 (talk) 00:01, 22 June 2011 (UTC)[reply]
It depends on what your prescription spectacles are correcting.
If it's purely long- or short-sightedness (which your description suggests) then all that will change is the depth of field the lens combination is optimum for. This is exactly how reading glasses work: they either add some positive dioptre value to your otherwise unspectacled eyes (bringing the near limit of your focussed depth of field nearer to you, to a comfortable reading position) or - if you have separate prescription spectacles for longer distances - their lenses are the same formula as those distance lenses plus a few dioptres to achieve the same effect; you can therefore achieve exactly the same result by wearing appropriate-strength simple reading glasses over your distance prescription glasses, and I've constructed clip-on reading glasses (by cannibalising and combining cheap reading glasses and cheap clip-on sunglasses) which are sometimes more convenient to use than swapping to the separate prescription reading glasses I also have (to my optician's amusement but not disapproval).
If however you had other sight aberrations, such as astigmatism (like myself), wearing two pairs of your usual prescription spectacles would over-correct your eyes by as much as they're undercorrected with no spectacles at all. {The poster formerly known as 87.81.230.195} 90.201.110.203 (talk) 01:56, 22 June 2011 (UTC)[reply]
June 22
Microstrip step discontinuity
Does anyone have a set of equations for the S parameters (or similar parameter set) of a microstrip step discontinuity? Readro (talk) 09:26, 22 June 2011 (UTC)[reply]
I may have some old paper notes with s-parameters derivations for most basic geometries, I can dig them out when I get home tonight. What parameters do you know already? You'll probably need the characteristic impedance of each strip, the geometry of the gap, and the strip width (and possibly the height). I probably also have some experimental measurements for 50-ohm copper-tape-on-FR-4, if you want those. Nimur (talk) 00:07, 23 June 2011 (UTC)[reply]
Since you know the impedances of each line, you should be able to determine the VSWR. Knowing that, you can apply the fllowing formala to obtain the S parameters.
From our page on S parameters
At the input port, the VSWR () is given by
What's the most complex amino acid polymers they've been able to create so far in experiments starting with completely lifeless beginning conditions and trying different changes to the test environment? 20.137.18.50 (talk) 18:12, 22 June 2011 (UTC)[reply]
A baby's head a very large compared to the woman's pelvis. That means the cervix has to dilate (get bigger) a lot, which takes time. --Tango (talk) 19:47, 22 June 2011 (UTC)[reply]
We have an article on childbirth that describes the phases of labor. Note that the time required to complete the phases of childbirth can vary quite a lot. The part of labor that is usually dramatized (i.e. the "pushing" part) can be variable and does not usually take "hours". --- Medical geneticist (talk) 20:56, 22 June 2011 (UTC)[reply]
Many animals do give birth with rather less effort, but the head of a human baby is very large in comparison to the size of its mother, due to us having evolved nice big brains. This page discusses the evolutionary balancing act between big brained babies and small pelvissed(?) mothers. Apologies if I just made-up a word! Alansplodge (talk) 23:29, 22 June 2011 (UTC)[reply]
The other issue is that we walk on two legs, which means our pelvises are rotated 90 degrees compared to other mammals. That means the baby has to come out between the legs, where there isn't much room, rather than behind the mother, where there is plenty of room. --Tango (talk) 23:36, 22 June 2011 (UTC)[reply]
Some of that only comes about if you force women to give birth in weird positions, like flat on their backs, or (*shudder*) on their backs with their feet in stirrups! (Is it true that American hospitals do that?) Childbirth is still hard and dangerous when you let the mother move into comfortable positions that feel 'right', there are still risks and difficulties, you still have to wait for the cervix to slowly dilate enough for the babies head so that you're less likely to rip important parts of yourself, there are still contractions and the various bleeding-to-death dangers, but the baby does tend to emerge somewhat 'behind' the mother rather than simply 'between the legs'. The mother often chooses positions in which gravity plays a large role in helping the baby out. 86.164.66.52 (talk) 09:29, 23 June 2011 (UTC)[reply]
This brings up an interesting Q, how could people be better designed for childbirth ? Perhaps the baby could be born out the front, above the hips, approximately where the navel is ? To accomplish this, humans (or perhaps just the females) might need to be a bit taller, to carry the baby higher, without impinging on other organs. StuRat (talk) 07:23, 23 June 2011 (UTC)[reply]
I wonder... has there been any sign of psychological benefits from the agonies of childbirth? Does the stimulus somehow tie in to maternal instinct? Is there any psychological downside to Caesarian birth? Wnt (talk) 19:42, 24 June 2011 (UTC)[reply]
Can't think how there would be any benefit. The only downside of a C-section would be from the scars it can leave. StuRat (talk) 18:34, 25 June 2011 (UTC)[reply]
Hand skin color
What is it that causes the skin on the palm of a dark-skinned person to be lighter than the rest of their body? Is it a lack of melanin? If so, why is there a difference? Dismas|(talk)20:08, 22 June 2011 (UTC)[reply]
In general, there's no pigmentation on the palms of the hands and the soles of the feet. This is observable on anyone "of color", such as Africans, Indians, etc. White folks don't have pigmentation on their palms and soles either, but not so obviously since it's all pretty much the same color. But check it out the next time you get a suntan. ←Baseball BugsWhat's up, Doc?carrots→ 22:21, 22 June 2011 (UTC)[reply]
The Melanin article doesn't answer the question, but one could infer that melanin occurs only in certain types of tissue, and not just the skin, by the way. But keep in mind that the nature of the skin on the palms and soles is somewhat different from the rest of the body's skin. No melanin, no hair, but plenty of lines and grooves that aid with gripping, which are of course absent on the back of your hands. ←Baseball BugsWhat's up, Doc?carrots→ 22:43, 22 June 2011 (UTC)[reply]
On googling this question, I have seen several claims on the interwebs (very possibly erroneous), that the epidermis on the hands and feet is thicker, and because melanocytes occur only in the underlying dermis, this makes the hands and feet appear lighter. Hence, the claim is that the thick overlying epidermis gives a lighter appearance even though the underlying tissue is just as pigmented as elsewhere. I have no idea if that is true, though it seems at least somewhat plausible. Dragons flight (talk) 23:29, 22 June 2011 (UTC)[reply]
(EDIT, just bet me to it Bugs) Another observation is that even hairy primates have bare palms and soles, so that leads me to suspect that there's a bigger difference to the skin on those areas then just lack of pigment. Vespine (talk) 22:54, 22 June 2011 (UTC)[reply]
One other difference is that the skin on the palms and soles has a stratum lucidum layer, unlike the skin on most parts of the body. I'm not saying the stratum lucidum is responsible for the lack of pigmentation there, I'm just supporting the notion that skin on the palms and soles is a somewhat different kind of tissue than skin found elsewhere. Red Act (talk) 23:35, 22 June 2011 (UTC)[reply]
And to add further to that, I'll mention the time I was pulling weeds during a school cleanup and yanked out some poison ivy (unknowingly). The palms of my hands were unaffected, but the tiny droplets of urushiol that landed on the back of my hand and forearm were enough to make a rather horrible rash. Tough skin there! Matt Deres (talk) 14:14, 23 June 2011 (UTC)[reply]
They would need to have an oil-based glue, not a water-based glue, as those would just dry out in a few hours or days. I'd also like to buy a vat of the stuff, so I can make my own mouse and insect traps. StuRat (talk) 01:55, 23 June 2011 (UTC)[reply]
The article on gum base describes this, and alas, it appears so - paraffin, microcrystalline wax, even potentially hazardous vinyl acetate. As with so many food products, as discussed in chewing gum, the composition becomes healthier and more sophisticated the further one looks back in time - chicle a few centuries ago, mastic gum in Eurasia in the time of Dioscorides, and a potentially therapeutic birch bark tar in Neolithic times. But now people can only afford to eat oil. Wnt (talk) 19:51, 24 June 2011 (UTC)[reply]
A 1949 book I have ("Money-Making Formulas") says for fly-paper, 5 to 7 parts boiled linseed oil, 2 to 3 parts gum thus and 3 to 7 parts of non-drying oil. It suggests cotton-seed, castor or neatsfoot oil will suffice. "Gum thus" is Frankincense. The book gives another recipe as 8 parts resin, 4 parts rape-seed oil and 1 part honey. Melt it all together and apply to paper. --TrogWoolley (talk) 18:45, 25 June 2011 (UTC)[reply]
Hessdalen lights -- a legit phenomena or a lot of bogus claims?
The Hessdalen Lights article does not inspire a lot of confidence, neither does the Project Hessdalen webpage with an image gallery featuring pictures mostly from the early 80s despite there apparently being an automatic monitoring station in place for a decade. Are these lights confirmed to be a regular, natural phenomenon by a real scientific authority, or are they just the usual run of the mill paranormal BS? The Masked Booby (talk) 00:50, 23 June 2011 (UTC)[reply]
It doesn't sound like a convincing scientific explanation has been found yet, but that's not the fault of the article. Do you doubt that the lights exist ? Or do you not think there shouldn't be a Wikipedia article on it ? StuRat (talk) 01:52, 23 June 2011 (UTC)[reply]
Any simple answers as to why (presuming from my Discovery Channel education) collapsing stars, black holes, etc. (spheres) seem to evolve into or gain Disk shaped phenomena. I am guessing that this will relate to planets that can evolve rings, and why solar system orbits tend to be on a plane as well. To me a balanced spherical object would have spherical phenomena not disk shaped processes forming from it. I will hazard a guess that this 3 to 2 dimensional process is at work when pulsar jets and such, take the process to the next level. Bonus points for cool links. 70.177.189.205 (talk) 00:51, 23 June 2011 (UTC)[reply]
A balanced spherical object would have spherical phenomena if it were not rotating, but most things in the universe rotate. It's natural for rotating systems to produce disk-like phenomena.--Srleffler (talk) 01:06, 23 June 2011 (UTC)[reply]
Removed request for medical advice. Question required diagnosis of problem and prognosis of possible healing of the problem. -- kainaw™03:28, 23 June 2011 (UTC)[reply]
Marijuana and chickens
If a chicken was fed a diet with some quantity of marijuana, would THC be excreted in the eggs in an amount detectable by a person eating those eggs? 68.231.149.156 (talk) 05:32, 23 June 2011 (UTC)[reply]
Fully charged and partially charged battery cells working together
I've read that you shouldn't have partially charged and new (or fully charged) batteries together. Does that apply only if they're in series or does it apply to parallel configurations too? --129.215.47.59 (talk) 10:11, 23 June 2011 (UTC)[reply]
Parallel could possibly be worse, since they are probably operating at different voltages, and this will put a lot of strain on the good battery. All this depends on what kind of batteries you are talking about. —Akrabbimtalk12:15, 23 June 2011 (UTC)[reply]
I experimented with standard AA batteries when I was a kid (for a science project) and found that if you drain a battery, it just stops working. If you force electricity through it by putting it in series with another battery, it will start to produce a little electricity (not much, but measurable) and then it will start to leak battery acid through the cardboard wrapping. So, my conclusion was that the reason you don't mix batteries is to avoid battery leakage. If they are in parallel, you will likely still get the same problem because there will be current flowing through the dead battery. I have no idea if this applies in any way to non-alkaline batteries. -- kainaw™12:22, 23 June 2011 (UTC)[reply]
Don't connect a new (or fully charged) battery and an old (or discharged) battery in parallel. There is no particular problem in connecting them in series except that the old (or discharged) battery will cause the two to have a lower voltage than you were planning. Dolphin(t)12:29, 23 June 2011 (UTC)[reply]
If you connect a good battery and a dead battery in parallel, the good battery will attempt to recharge the dead one. The results vary depending on battery chemistry. --Carnildo (talk) 00:21, 24 June 2011 (UTC)[reply]
Some older programmable calculators and personal organizers have two kind of batteries in it: normal ones and a backup one that's only used so that the device does not forget the data in their memory while you replace the normal batteries. These backup batteries thus drain very slow and are typically intended to last for the whole life-time of the device. (These days the data is instead saved to flash or solid state memory instead, but that of course wasn't yet available cheaply when these devices were made.) If you shouldn't mix new and old batteries, how do these devices work? – b_jonas13:54, 24 June 2011 (UTC)[reply]
There are various ways of isolating one battery from another. The simplest I can think of is to have the main batteries hold a relay in one position; disconnecting or discharging the main batteries will cause the relay to switch to the backup battery. There are other circuits that give the same effect, with varying degrees of sophistication and reliability. --Carnildo (talk) 00:14, 25 June 2011 (UTC)[reply]
gene difference between Man, Woman, Chimpanzee?
I just watched a video about a Chimpanzee use a frog's mouth for masturbation. This really shocked me... Then a question came into my mind:genetically speaking, my gene is more similar with a male Chimpanzee than any woman in the world?(provided that woman has no Y chromosome)Nilman (talk) 17:03, 23 June 2011 (UTC)[reply]
You can't really talk about the genetic difference between males and females of the same species versus males and females of another species, I don't think. Homo sapiens is considered a single species for the purposes of figuring out genetic distance from other animals. So I think it's pretty clear the answer is "no". --Mr.98 (talk) 17:19, 23 June 2011 (UTC)[reply]
I am not an expert, but presumably there would be no problem with just feeding the data for males only, or the data for females only, in the relevant algorithms and proceed as one would do for computing the genetic difference between species that do not have genetic sex differences. In fact, I would expect that that's the basic algorithms, and that any special treatment for the sexes (if it exists at all) is an add-on. HansAdler17:51, 23 June 2011 (UTC)[reply]
I think I see where you're coming from. You think that since only males have the Y chromosome, that therefore that genetic portion is unique to males, so 1 of the 46 total chromosomes, or 1/46, or over 2%, should be different, which, indeed, would make that difference about the same as that between humans and chimps. The flaw in that theory is that many of the genes on the Y chromosome are duplicates of those on the X chromosome, so aren't unique to males. StuRat (talk) 18:44, 23 June 2011 (UTC)[reply]
Note that counting chromosomes is a flawed approach. In this case, the Y chromosome is small compared to the X chromosome. In the case of humans it is only about 58 million base pairs (compared to 153 million for the X chromosome or 3 billion for the human genome) and more importantly only has 86 currently recognised genes (compared to 2000 for the X chromosome and 20000 to 25000 for the human genome). BTW the Pseudoautosomal regions don't really have that many genes (only 29 have been identified so far). Nil Einne (talk) 00:42, 24 June 2011 (UTC)[reply]
Hallo, as a German Wikipedian who ocasionally translates articles from the English Wikipedia I came over that article and am wondering about the a good part of that section. As a given wind direction normally means the way from which the wind blows the given data
The intense counterclockwise rotation of the low was made apparent by the changing wind directions around its center. In Buffalo, New York, morning northwest winds had shifted to northeast by noon and were blowing southeast by 5:00 p.m., with the fastest gusts, 80 mph (130 km/h), occurring between 1:00 p.m. and 2:00 p.m. Just 180 miles (290 km) to the southwest, in Cleveland, winds remained northwest during the day, shifting to the west by 5:00 p.m., and maintaining speeds of more than 50 mph (80 km/h).
seem to be incorrect. If we take this as a cartesian coordinates system then it seems wrongly that in Cleveland the north moving counter clockwise rotating low produces northwesterly winds the whole day what suggests that Pittsburg, OH the whole day low within the IIIrd quadrant while Buffalo initially was in the same quadrant, later in the second and after that in the first quadrant. What of course does not make it a counterclockwise rotation.
Maybe I just don't get it, maybe the article was vandalized some time back or some editor accidentally could not keep east and west from each other. The author who wrote the most part of the article appearantly isn't active regularily anymore so asking him seems not to be an option at this moment. Any thoughts? --Matthiasb (talk) 17:39, 23 June 2011 (UTC)[reply]
It makes sense to me. Surface charts from the 8th through the 10th show that the storm dug south into the Appalachians, ending up south and slightly east of Buffalo, which explains the northwest winds, and the shift to NE as the storm retrograded back NW to a position just northwest of Buffalo (source). Once there, it produced the southeast winds, which were as severe as they were due to the close proximity to the low-level circulation center. In the meantime, however, Cleveland remained on the western side of the storm, which is consistent with an extended period of northwest winds. Juliancolton (talk) 18:03, 23 June 2011 (UTC)[reply]
I can't open that link but the fact that there was a blizzard doesn't say anything about wind direction. What information does that .djvu contain? Rmhermen (talk) 17:34, 24 June 2011 (UTC)[reply]
Me either, I don't have a .djvu-reader on my weekend machine. But the point is that in deed there were two converging systems, one frontal near or over the Upper Peninsula and another cyclonic which developped somewhere further south near Washington or over Virginia. The latter wandered to the north. For some time Buffalo still experienced the northwest winds form the (let's call it) U.P. system, later came under influence of the (say) D.C. low, first in its second quadrant meaning it experiencs north eastern winds. When the low level center moved near Buffalo on the West, Buffalo shifted to the first quadrant, lying right of the center, so got south eastern winds. The D.C. low moved further to the North and finally its third quadrant got in phase with the NW winds of the U.P. system, meaning that the rotating winds of the D.C. low increased the winds of the U.P. low and things got worse. As Julian said, Cleveland stayed on the west of the D.C. low the entire time and never came directly into influence of the D.C. low. My earlier mistake was that I presumed wrongly that there was only one low, the rotating swirl of the D.C. low. --Matthiasb (talk) 18:03, 24 June 2011 (UTC)[reply]
Neurons Attached
How are the neurons (cells) attached to the rest of the brain matter? Are the neurons completely hidden inside the actual brain, like it gives a cover to the neurons and synapses? — Preceding unsigned comment added by 70.136.159.57 (talk) 18:46, 23 June 2011 (UTC)[reply]
I just checked the wikipedia article on brain, and it seeems the human brain is made up of roughly equal amounts of two kinds of cells, neurons and glia. thx1138 (talk) 20:21, 23 June 2011 (UTC)[reply]
How are these cells, neuron, and glia attached to the actual brain matter? I know the synapses and cells are connected almost like a wire, but what about the actual brain itself, or the brain tissue? — Preceding unsigned comment added by 71.143.159.249 (talk) 20:56, 23 June 2011 (UTC)[reply]
I think the OP is just having trouble conceptualizing what the brain matter looks like. As the other responses have indicated, the neurons and glial cells are the principal cellular components of brain matter, and they are surrounded by their own cellular processes (axons and dendrites) and encased in extracellular matrix. All of the material surrounding the cell bodies is called the neuropil. The articles on neurons and glia have pictures that show the histology of the nervous system (one example shown to the right). In this picture, the darkly stained cells are pyramidal neurons, and you can see how extensive their cellular processes are. All of the lightly stained material is the extracellular matrix, kind of like the glue that sticks everything together. For a more detailed look at neurohistology, you could try this external site hosted by the University of Minnesota. --- Medical geneticist (talk) 22:35, 23 June 2011 (UTC)[reply]
Please note that the SMI-32 monoclonal antibody does not stain every neuron, but subsets.[10] Staining all neurons would make the structure of any one of them difficult to make out. Golgi's method was an important advance which overcame this by some still rather mysterious photographic process. Wnt (talk) 19:34, 24 June 2011 (UTC)[reply]
Polonium in cigarettes
According to this article, the average cigarette contains .04 picocuries of Polonium-210. Po-210 has a half life of 138.376 days. How long would one have to store cigarettes in order to have them decay to essentially negligible (from a health and/or physical point of view) levels of Po-210? --Mr.98 (talk) 19:56, 23 June 2011 (UTC)[reply]
It's not necessarily safe to assume that, just because the existing Po-210 has decayed, you don't have Po-210. Po-210 is in the uranium chain, and if there are other elements above it in the chain also in the leaf, they could decay and you could get more.
However the next nuclide above it that has a half-life more than a few days is Radium-226, and the chain passes through radon, which is a gas. So I don't know what would happen with that. Intuitively I suspect a significant amount of the gas would stay in the cigarette until it decayed, but I'm not sure. --Trovatore (talk) 20:07, 23 June 2011 (UTC)[reply]
Hmm if I read that decay chain correctly, "the next nuclide above [Po-210] that has a half-life more than a few days" is Pb-210 (22.3 years), not Ra-226. The chain starting at Pb-210 doesn't pass through radon, only through Bi-210. 98.248.42.252 (talk) 15:06, 24 June 2011 (UTC)[reply]
I guess you're right. So the question is, does the polonium in the cigarettes come from polonium in the fertilizer, or lead-210 in the fertilizer? If it's from the lead-210, then waiting for the polonium to decay is useless; you'd have to wait 50x or so as long for all the lead-210 to decay. --Trovatore (talk) 19:37, 24 June 2011 (UTC)[reply]
As whole-body exposure, sure. The problem with polonium is that it can be concentrated in tiny particles that stick around and keep irradiating the same nearby cells. There is serious concern that this is a significant contributor to smoking-related lung cancers. Personally I'm not in a position to know whether that's justified or not. --Trovatore (talk) 20:53, 23 June 2011 (UTC)[reply]
This is a minor contributing factor to lung cancer -- it does contribute somewhat, but most of the lung cancers in smokers are due to nasty chemicals like benzopyrene, phenol, etc. (which are inhaled in much greater amounts than polonium). 67.169.177.176 (talk) 21:53, 23 June 2011 (UTC)[reply]
(ec) The NYTimes article suggests that for pack-and-a-half a day smokers, it's equivalent to 300 chest x-rays over a year. That strikes me as a fairly significant source of cumulative radioactivity in a fairly risky exposure route (burned and deliberately inhaled deep into the lungs). But I'm not a health physicist. --Mr.98 (talk) 20:57, 23 June 2011 (UTC)[reply]
One group estimates that it causes 11,700 deaths yearly.[11] But oddly enough, four World Trade Center attacks a year is just 2% compared to the 5.4 million deaths from tobacco overall (both figures are worldwide statistics). Also, I'm seeing claims it's more from phosphate fertilizer than nuclear testing, at least nowadays; makes you wonder where else that fertilizer goes. Wnt (talk) 18:23, 24 June 2011 (UTC)[reply]
(*groan*) Do you have to drag the 9/11 attacks into this? Remember, there's no moral equivalence whatsoever -- death from cigarettes is due to the voluntary consumption of a harmful product (and therefore is the moral equivalent of, say, getting yourself killed due to reckless driving), while the deaths in the 9/11 attacks were due to a deliberate attack on our homeland by evil savages whose goal is to kill or subjugate everyone in the world. Comparing the two is an insult to all who lost their lives in the 9/11 attacks. Also, comparing the deaths from the 9/11 attacks in the USA alone (which they were) to any worldwide statistic is misleading even from a purely mathematical point of view. 67.169.177.176 (talk) 21:01, 24 June 2011 (UTC)[reply]
Let's not forget that the companies for many years pretended their cigarettes were safe; then they sold "low tar low nicotine" cigarettes knowing that only the machines used to test them were actually getting lower tar and nicotine. There is not a complete lack of moral responsibility here. To editorialize just a moment, there is also not a complete lack of responsibility when you spend $1 trillion on a war mostly to make an excuse for why you got out of Saudi Arabia like Osama bin Laden told you to, but spend only a few billion trying to help smokers quit or trying to cure cancer. It's fair to make a numerical comparison. Wnt (talk) 00:15, 25 June 2011 (UTC)[reply]
"Spend $1 trillion on a war mostly to make an excuse," blah blah blah?! Come ON, are you REALLY as stupid as this -- or are you trying to PURPOSELY disinform the public to undermine their will to fight the enemy?! This war is NOT about making any kind of excuses -- it's about FINDING AND KILLING terrorists and their supporters, and about AVENGING the evil they have done to our country! And even if we spend ten times as much money fighting this war while suspending all other government spending (medical etc), it would still be justified because we MUST avenge these dastardly attacks at any cost! Besides, when you cited the statistics for cancer deaths, you gave the worldwide statistics as if we had any duty to try to cure every cancer patient in the world, even though even in terms of government spending priorities, our government only has a duty to help our citizens who suffer from cancer, not some Paki or Somali savages! So if you want to make a fair numerical comparison, give the statistics for the USA alone, not for the whole world (most of which isn't worth saving anyway)! And last but not least, your figure of "a few billion" is DELIBERATELY MISLEADING because it includes ONLY government spending on cancer research, NOT the many billions in PRIVATE funding spent on it! So go look up the true statistics, and don't come back here until you do!!! 67.169.177.176 (talk) 09:36, 25 June 2011 (UTC)[reply]
Correction to the above: 58 BILLION dollars is incorrect -- I misread the number because Wnt's comment about the War on Terror being "an excuse to get out of Saudi Arabia" made me so mad that I was literally seeing double. The correct number for private, nonprofit foundations only is 58 million for the year 1997. All the same, for every dollar spent by the government on cancer research, more than a dollar is spent by the medical industry and by nonprofits, so the actual spending on cancer research is still more than double what Wnt would have us believe. And besides, what really matters is not how much money gets spent on curing cancer, but how effective it is in actually reducing cancer deaths: check out the article War on Cancer and see for yourselves the significant across-the-board decrease in cancer deaths in our country. As for ALL my other comments on this thread, I still stand by them. 67.169.177.176 (talk) 18:41, 25 June 2011 (UTC)[reply]
And another piece of statistics from www.cancer.org: The number of deaths from lung cancer in the USA (from ALL causes, including asbestos, PAH's, etc. -- not just from tobacco) in 2011 is 156,940 (which is still a lot) -- NOT 5.4 million! 67.169.177.176 (talk) 10:49, 25 June 2011 (UTC)[reply]
And a message to everyone else regarding User:Wnt: this user has recently made deliberately misleading statements regarding British and American history; for example, in a recent discussion he/she stated that workhouses were intended as a system of extermination through labor, similar to the Soviet Gulag, despite ample evidence to the contrary; made preposterous and deliberately defamatory statements accusing the British people of cannibalism and of systematically murdering their own poor; and purposely tried to conflate racial discrimination in the United States with extermination through labor. In light of this, any statements made by the above user regarding history and/or current affairs should be regarded as having zero credibility. 67.169.177.176 (talk) 11:07, 25 June 2011 (UTC)[reply]
I don't think this is the right place for that kind of rant. It's an off topic, controversial, impolite, white noise. Dauto (talk) 14:46, 25 June 2011 (UTC)[reply]
I'll admit that I am prone to stray off topic now and then in these answers - though the numerical comparison was not. And I'm not anti-American, just opposed to the Republican inner circle which has terribly abused the high-minded ideals of an underinformed and overly trusting populace. (Nigerian yellowcake, Valerie Plame, remember?) Tobacco does kill 5.4 million yearly.[12] It is no ordinary delusion that makes someone believe 3000 > 5400000, and yet I will admit, I don't think 64.169's opinions are unusual. Wnt (talk) 21:07, 25 June 2011 (UTC)[reply]
Or let me put it this way: What makes you think that the larger portion of the 5,400,000 are of more importance than the 3,000 (much less the 156,940)? 67.169.177.176 (talk) 23:54, 25 June 2011 (UTC)[reply]
To be clear, not all tobacco deaths are from lung cancer - heart disease, COPD, emphysema, for example. See health effects of tobacco. And of course the U.S., having made great strides early on toward reducing smoking, has a lower tobacco death rate than some of the developing countries to which tobacco is exported. Wnt (talk) 00:14, 26 June 2011 (UTC)[reply]
Crystal Violet Tetrazolium Agar
How does CVTA select for gram negatives? The agar has roughly 1% 2,3,5-Triphenyl Tetrazolium Chloride (TTC), which I am pretty sure is the selective agent. After some reading, it might have something to with the ability to reduce TTC in the electron transport chain, but what is different about gram negatives that help them grow better? — Preceding unsigned comment added by 132.236.177.203 (talk) 20:57, 23 June 2011 (UTC)[reply]
Suppose you have some antibiotic pills from a less-than-reputable source, and you suspect that they might actually be placebos. How can you test this to be sure, other than by administering them to a live patient and seeing if they work? 67.169.177.176 (talk) 21:56, 23 June 2011 (UTC)[reply]
From our article, Analytical chemistry "is the study of the separation, identification, and quantification of the chemical components of natural and artificial materials." Specific chemical assay techniques exist for a variety of types of chemical; you may need a biochemistry lab, inorganic chemistry lab, and so on, depending on what substance you're trying to positively- or negatively detect. This is an incredibly broad question; but you can at least get an overview of the more common instrumental methods used to identify chemical compounds. Nimur (talk) 22:32, 23 June 2011 (UTC)[reply]
Actually, I have a lot of experience in analytical chemistry -- I've spent much of my life so far working in chemistry labs and petrochemical refineries. What I wanted to know was, what are the best techniques to distinguish penicillin-type antibiotics from inert placebo pills. In particular, is there any kind of "field test" that allows this to be done without resorting to complicated lab equipment such as NMR machines and the like? 67.169.177.176 (talk) 01:19, 24 June 2011 (UTC)[reply]
Just for the sake of clarity, from placebo: "Sometimes patients given a placebo treatment will have a perceived or actual improvement in a medical condition, a phenomenon commonly called the placebo effect" (emphasis mine). So administering the pill and recording positive results would not be a reliable indicator that the pill contained active ingredients that were the direct cause of recovery. (This part of why e.g. homeopathy can garner many anecdotal successes.) SemanticMantis (talk) 01:27, 24 June 2011 (UTC)[reply]
Besides analytical chemistry, one could also probably test for their effect, by growing a bacterium that is known to be susceptible to the antibiotic in a petrie dish, and grinding up a sample of the pills and adding it to the dish. One would probably want to do a controlled study with several dishes, some getting pills that are known to be good, some getting a placebo, and some getting the questionable pills.--Srleffler (talk) 02:16, 24 June 2011 (UTC)[reply]
you have some antibiotic pills from a less-than-reputable source, This is the part that concerns me: What are you doing with antibiotics from "less then reputable" sources? I'd be throwing them out. I'm all for "do it yourself" attitude, but if you are really concerned about the product and it was procured legally, I'd be contacting the local drug regulatory authority, like the FDA in the states. Vespine (talk) 02:22, 24 June 2011 (UTC)[reply]
"What are you doing with antibiotics from less than reputable sources?" I'm not. Just so you know, this has to do with research for my second novel, which is a sequel to the one that's just coming out. You might remember me asking about bear maulings, backfiring shotguns, emergency surgery, landing in bad weather using only an NDB for guidance, etc. (or maybe not -- that was before my year-long boycott of Wikipedia, and I think I had a different IP address back then). Well, my sequel will be mainly about a large-scale avalanche rescue, but there will be a little bit about the bear-mauling victim from the first novel. What happens with him is, the rescue team brings him to a hospital in Canada for follow-up treatment, but he ends up having to wait for a long time to get the surgery because of rationing, and in the meantime he gets worse because the hospital has bought its antibiotics from India to save costs, and they turn out to be bad. Hope this comment makes it clear to you. 67.169.177.176 (talk) 21:19, 24 June 2011 (UTC)[reply]
It's worth further noting that a hypothetical "less-than-reputable source" isn't limited to providing a binary "perfect" or "placebo" choice when considering what sort of functional or field assays one might try to perform. The active ingredient could be cut with neutral filler, or with a cheaper alternative antibiotic. In the latter case, the pill might well appear to have potent antibacterial effect, but unless the test bacteria were carefully chosen (or there were a whole panel of them, each with different, well-characterized antibiotic resistances) you'd have no way of knowing the label matched the contents. (It's also not trivial to perform controlled tests of dose-response under field conditions, so the amount of active ingredient would be quite challenging to reliably ascertain.) For that matter, one can get a nonspecific bactericidal effect just by replacing the antibiotic with potassium cyanide. TenOfAllTrades(talk) 03:59, 24 June 2011 (UTC)[reply]
There's actually a relatively simple quantitative test for the strength of antibiotic potency. See Kirby-Bauer antibiotic testing. The concept is you put a dilution series of the antibiotic of unknown strength onto a filter disk on what will grow to be a lawn of test bacteria. You then compare the diameter of the inhibited zone with that of a dilution series of an antibiotic standard when tested under the same conditions (which in practice means "at the same time, preferably on the same plate"). Now, in addition to not being able to tell the difference between antibiotic and cyanide, this will only tell you the ability to kill that particular bacteria you tested. If the antibiotics are different, you won't get consistent results with different bacteria. For example, if your standard was streptomycin, but your unknown was actually penicillin, you'll get different equivalencies if you test with e.g. Salmonella versus Staphylococcus. So if you have a completely unknown sample, your best bet is to go with a standard analytical method. Note that you might not need to go all the way to NMR - HPLC/GC can work just as well, assuming you have standards. Given the lack of chromophore on most antibiotics, though, detection may be an issue, although there are a number of detectors which may work, some of which have been miniaturized and simplified enough that they might be considered for use in a "field test". -- 174.24.222.200 (talk) 16:12, 24 June 2011 (UTC)[reply]
So he could get cultures of a few pathogens the drug is supposed to fight, make petri dishes with nutrient gel, dilute the "antibiotic" and test effectiveness. Then to make sure it is not just some harmful poison or disinfectant, couldn't he administer it to suitable test animals (rats, mice, cats, dogs) in increasing doses to determine the LD50? Isn't this about what pioneer microbiologists did every day over a century ago? Edison (talk) 16:15, 25 June 2011 (UTC)[reply]
Just for the sake of reality in your novel: someone mauled by a bear in Canada would be in an emergency room at a hospital, and any necessary surgery would be done right away. (Only elective surgeries have ever had waiting lists.) There has been no case of below-standard drugs being sold in Canada. As far as I can confirm, purchases are made directly from manufacturers, most of which are based in Canada and the US. This would all be more likely if you placed your characters in the U.S. where surgery might well be delayed due to lack of patient funds and hospitals, who purchase their own drugs, might well be tempted by the cheaper sources with questionable quality controls.
In the United States, emergency surgery is never delayed (only elective surgery). Likewise, purchasing drugs from cheaper sources is unlikely for US hospitals, since they can pass the costs to the patient (although now that we have Obamacare, they just might). The only way someone in the US would become a victim of counterfeit drugs is if he/she was given a prescription for outpatient antibiotic treatment and decided to save on costs by buying from one of those "too good to be true" suppliers. (Or from an online clinic.) 67.169.177.176 (talk) 22:04, 24 June 2011 (UTC)[reply]
Also for the sake of clarity: the emergency part of the surgery has already been performed in the field (toward the end of the first novel), and the patient has been transported to the hospital several days later to get some broken bones reset properly (which the field surgeon on the rescue team could not do for lack of proper equipment). I don't think this would qualify as an emergency surgery, since there's no gangrene involved (the fractures have already been debrided). Would this still be given urgent priority? 67.169.177.176 (talk) 22:12, 24 June 2011 (UTC)[reply]
If the bones need surgical setting, then yes, it's considered urgent. "Elective", in this case, would be something like reconstructive plastic surgery. --Carnildo (talk) 00:24, 25 June 2011 (UTC)[reply]
June 24
What kind of clothing do workers wear when doing work on power lines?
Most Linemen were standard personal safety equipment: gloves, safety hat, etc. For linemen that work on the sort of very high tension wires where they need protection from the electricty itself, they wear a sort of chain mail suit which acts as a personal Faraday cage. See this video. But most linemen don't need that sort of protection. The guys working in the cherry picker working on the lines running next to the road usually just wear a hard hat, gloves, and sturdy clothes. --Jayron3201:19, 24 June 2011 (UTC)[reply]
(ec) Prepare yourself for a big surprise! They don't wear rubber boots -- they wear clothes made of steel wires. Amazing? Incredible? Well, what this does is, it allows the dangerous high-voltage electricity to flow around their body rather than through it. 67.169.177.176 (talk) 01:24, 24 June 2011 (UTC)[reply]
I don't know, but I bet they piss on the ground far less than the average person at that height above street level does (however low that percentage is normally already.) --188.29.15.168 (talk) 01:24, 24 June 2011 (UTC)[reply]
FYI, a third rail "only" carries 500-800 volts (which can still be dangerous); a power line, on the other hand, can carry anywhere between 11 kV (your typical local distribution line on wooden poles) and 1150 kV (the high-voltage transmission line between Irkutsk and Alma-Ata). See the difference? 67.169.177.176 (talk) 21:50, 24 June 2011 (UTC)[reply]
I guess they didn't have 500 kV, which might be enough to create sparks between the droplets. Sometimes I wonder how large the current is when rain flows over the insulators of a high-voltage line. Icek (talk) 07:32, 24 June 2011 (UTC)[reply]
Shockingly, peeing onto an electric fence is not recommended. I wouuuld know this from having not seen the live wire that zapped me. --Modocc (talk) 15:07, 24 June 2011 (UTC)[reply]
WP:OR I've heard of a worker who was fatally electrocuted when he (unknowingly) pissed on a live electric cable which was carrying "only" 11 kV (and was insulated, as well). 67.169.177.176 (talk) 21:36, 24 June 2011 (UTC)[reply]
Mythbusters agree on that one, the test above was for the third rail where a person would be too far that urine was bound to break up. (This is referenced in the above article I believe because I read it a few weeks ago.) For an electric fence the person can be much closer. I do agree that applying a low voltage situation to the high voltage of power lines doesn't work Nil Einne (talk) 05:51, 25 June 2011 (UTC)[reply]
It depends on the kind of work that is being done. For routine maintenance or inspection on very important wires, shutting them off is not necessarily an economical or desirable option (shutting off the electricity for an entire region, for example, can cause more danger to more people than it would to a properly trained operator). This is a pretty amazing video showing how inspections of high voltage transmission wires are done. As you can tell, they are very live — the operator is just kept away from anything that could ground them. He does not appear to have anything protective on (because he's not grounded). --Mr.98 (talk) 14:44, 24 June 2011 (UTC)[reply]
That hooded suit he's wearing is probably full of metal wires - it's a lighter version of the chain mail mentioned above. --Tango (talk) 22:52, 24 June 2011 (UTC)[reply]
Most electric utility workers you see working on poles next to the road are working on subtransmission lines of say 4kv to 34kv AC phase to phase. The transmission lines of 69kv, 138k and higher are a different kettle of fish. No practical amount of rubber protective gear would insulate a grounded worker from death when he touched an energized transmission line, so he works it deenergized or while isolated from ground, and the conductive suits come into play. If the transmission line worker were also touching something grounded, the conductive suit would not protect him from incineration. At the lower subtransmission and distribution voltages, insulation is practical and live line work is done commonly. The gear is beyond what an amateur could likely conjure up so do not attempt it. US utilities would typically require them while working on 12kv or 4 kv wires to wear a hardhat, approved safety glasses, fire retardant shirt and pants, "serviceable shoes" which have substantial soles and come high enough to provide ankle support (no sneakers or running shoes). No metal conductors under the protective gear. If they climb the wooden pole, they will use a climbing belt which goes around the pole and they would have "gaffs" attached to their boots which dig into the pole. They have to lean back for the belt and gaffs to hold, and they lean in too much, they will find themselves sliding down a splintery pole. If they are going to be near live high voltage wires they will wear thick rubber gloves tested to insulate to a higher voltage than the energized equipment in question (way thicker than dish washing rubber gloves), which have leather protective gloves outside them to protect from abrasion. They are likely to wear a harness for fall protection, with a rope which extends to break the fall in a shock absorbing way. The harness also allows them to be more easily lowered to the ground by rescuers if they are knocked unconscious. They are likely to additionally wear rubber sleeves which protect the arms. All this is heavy, cumbersome and hot, and there is a temptation to take short cuts, so there are commonly unannounced safety audits by supervisors. Mistakes and carelessness lead to death, severe burns, and amputations of burned limbs. A worker doing some switching operation at ground level might wear variations on the above equipment, less the climbing belt, gaffs, and harness, but adding an insulating cape and facemask, since a switching error could produce a huge fireball for a bit until fuses or breakers operated. Power voltages of 480 and up are good at sustaining an arc which incinerates everything in the room, besides the electrocution hazard. Edison (talk) 15:58, 25 June 2011 (UTC)[reply]
This is an interesting problem. A person of length L stands on the ground, wearing perfectly insulating shoes. He is right underneath a powerline at a height of H above the ground. The powerline is at a voltage of V, the angular frequency is omega. Estimate the current through the person. Count Iblis (talk) 18:36, 25 June 2011 (UTC)[reply]
Negligible. It's only going to be significant if you get arcing, where the air is turned into plasma and becomes much more conductive. --Tango (talk) 18:42, 25 June 2011 (UTC)[reply]
From time to time I get muscle cramps, usually in a calf or hamstring, at which time my body basically tells my brain that I need to do whatever it takes to straighten that muscle and prevent it from contracting further. After pulling my toes towards my knee (calf cramp) or straightening my leg (hamstring cramp), the cramp passes (unwinds, kinda) and the muscle returns to normal function. I think most people here have experienced this process, certainly any athletes. What I'm curious about is what would happen if I did not stretch out the cramping muscle? if I just let it continue to seize up and contract? Does the cramp impulse eventually dissipate? can the muscle actually damage itself through a prolonged contraction? I've always wondered about this but have never been quite curious enough to put up with the pain and cognitive dissonance (why aren't you straightening that muscle? this is an emergency!) to experiment on myself... The Masked Booby (talk) 02:17, 24 June 2011 (UTC)[reply]
I can speak (WP:OR) for foot, calf and quad, ab- and adductor cramps. I was not able to get out of bed easily for about 10 days post surgery, during which time I had horrendous cramping. There is a peak point (very painful) in a cramp and it can hold there for what seems like forever, but is probably measured in minutes, and then it fades. You can't think about much else when it is happening, and I can now understand how cramps can cause swimmers to drown. I am not suggesting this will be everyone's experience. The article Cramp says nothing about possible damage from them. Bielle (talk) 02:32, 24 June 2011 (UTC)[reply]
In corroboration of Bielle, I can also offer some personal experience. For a period during my teens, I suffered occasional calf muscle cramps when sitting on wooden chairs in my (very crowded) school chapel during longer Sunday services. Since there was already very little space to move, and because drawing attention to myself was something to be avoided, I just had to leave my muscle contracted and grit my teeth until the cramp passed of its own accord after a few (2-4) minutes (incautious tensing of the muscle for 10 minutes or so after it had would sometimes cause it to return). No apparent muscle (or tooth) damage resulted. {The poster formerly known as 87.91.2301.95} 90.201.110.36 (talk) 17:29, 24 June 2011 (UTC)[reply]
Sugar water injection
On season 3 episode 12 of the espionagetelevision seriesBurn Notice, a character uses a syringe to inject another character with sugarwater in order to deceive that other character into believing that he had been injected with a deadly poison when in fact he had been injected with something harmless. Is it really true that injected sugar water is harmless? And why would the character use sugar water rather than just plain water? Was the sugar an unnecessary detail by the writers? —SeekingAnswers (reply) 14:53, 24 June 2011 (UTC)[reply]
Typically, doctors will use saline when giving fluids intravenously. One of the main reasons for this is that they want a solution which is isotonic with blood, so that the cells don't swell up from water absorption (see picture on that page). With saline, the osmotic pressure of the solution is regulated by salt, but osmotic pressure can also be regulated by any solute, including sugar. Why did the writers specify sugar instead of saline? I'm not sure, but my guess is that they were making a connection to the concept of a placebo, which are sometimes colloquially referred to as "sugar pills". -- 174.24.222.200 (talk) 15:46, 24 June 2011 (UTC)[reply]
Initially, it would have to be determined experimentally, for example with an osmometer, or by observing the effect of solutions of various concentrations on red blood cells. However, since osmotic pressure is a colligative property, once you figure out the concentration needed for one solute, you can figure it out for pretty much any other. Typical IV saline is 9g/L, which is about 0.154 M NaCl, or 0.307 M solute molecules (0.154 M Na+ + 0.154 M Cl-). So you would need about a 0.3 M sugar solution. For a typical 10 mL syringe, this works out to about 1.05 g of sucrose (or 550 mg of glucose). A quick experiment with a kitchen scale shows this to be about 1/4 of a tsp of sucrose (probably about the amount of sugar in a small hard candy). - Regarding swollen cells, a temporary swelling of the cells isn't so much of a problem, (as it will likely reverse when the cells hit general circulation, and the hypotonic bolus is diluted out) but that if the solution is hypotonic enough, and the cells are bathed in it long enough, the cells may swell to the point at which the membranes rupture. This is called hemolysis, and if it happens to enough of the cells, can be fatal (although I doubt a ~10mL pure water bolus would cause enough damage to be fatal in most cases). -- 174.24.222.200 (talk) 17:56, 25 June 2011 (UTC)[reply]
Note that the sugar solution given in hospitals is highly diluted (with water). Injecting a stronger concentration of sugar could be deadly. StuRat (talk) 17:19, 24 June 2011 (UTC)[reply]
An strongish isotonic balanced, glucose injection would cause a sugar rush. A subject so primed could very well believe this to be the symptoms of poisoning. This sort of conviction was observed by doctors in the Nazi death camps during their experiments. During the the 1991 Iraqi missile attack on Israel, a number of people suffocated in independent incidents, thinking that carbon dioxide poisoning was confirmation of a gas attack and so dared not to take there gas masks off (they forgot to take the seals off the filtration canisters). [13] --Aspro (talk) 21:49, 24 June 2011 (UTC)[reply]
Also questioning the normal (nondiabetic) person perceiving a "sugar rush" from glucose in the bloodstream. If he eats candy or drinks a 32 ounce sugar soft drink, there will be heightened glucose in the bloodstream, leading the pancreas to release insulin, preventing the blood sugar from going very high. Consider the old glucose tolerance test, in which the blood sugar goes high after a big dose of glucose orally, but promptly comes back down in the normal person. No strange sensation in the gluconormal. Edison (talk) 15:32, 25 June 2011 (UTC)[reply]
32 ounce, is that 2 pints? Can someone drink 2 pints of sugary drink? That is a huge dose, surely? Half a pint would be a more normal drink but still quite a hit of sugar. Or am I wrong about the quantity? Itsmejudith (talk) 21:37, 25 June 2011 (UTC)[reply]
It is a huge dose, but people really do drink it. Note that it's two American pints; if you're used to Imperial pints, those are bigger. --Trovatore (talk) 00:25, 26 June 2011 (UTC)[reply]
Fish are incapable of closing their eyes, so they look awake when they sleep. Dolphins meanwhile sleep with one eye open. ~AH1(discuss!)16:17, 24 June 2011 (UTC)[reply]
I'm not sure there is a term, but I will point out that there are similar photos of Bush as well (do a Google Image search for "Bush halo" -- it seems pretty common given the practice of putting seals in the background). (And for something else entirely, do a Google Image search of "Ashcroft Spirit of Justice".) --Mr.98 (talk) 02:07, 25 June 2011 (UTC)[reply]
[14] Can anyone tell me what kind of bug this is? The photo was taken in the US state of Connecticut. It's roughly 5+ inches long. Thanks, Dismas|(talk)01:00, 25 June 2011 (UTC)[reply]
Most mammals (including humans), as well as amphibians, excrete most of their nitrogen waste as urea, in urine. Fish tend to get rid of nitrogen waste as ammonia. Birds and reptiles metabolize nitrogen waste to uric acid. Uric acid is not very soluble in water, so birds don't excrete it dissolved in urine, the way mammals do urea. Rather, it is excreted with other solid waste, in the form of a white paste. Buddy431 (talk) 04:19, 25 June 2011 (UTC)[reply]
And because uric acid comes in the form of white crystals, hence the colour. Yes, I wanted to ask this additional question but found out from the article. --Ouro (blah blah) 07:28, 25 June 2011 (UTC)[reply]
No, much to the regret of gout sufferers, humans do not excrete urea, or even allantoin like pigs do, but the sparingly soluble uric acid. I remain curious whether the high uric acid levels help account for why so many predators spit humans out, as eating shark meat high in uric acid or other ammonia rich compounds can be harmful. Wnt (talk) 22:23, 25 June 2011 (UTC)[reply]
You're wrong - read the articles urea and uric acid. Urea is the waste product in mammals (including humans) for most sources of nitrogen. Uric acid is only the end product for the Purine metabolism. Most mammals further break uric acid (from the Purine metabolism) down into Allantoin via Urate oxidase. Birds and reptiles, on the other hand, convert nearly all of their nitrogenous waste into uric acid (and excrete it along with their feces). Buddy431 (talk) 03:34, 26 June 2011 (UTC)[reply]
From uric acid: "In humans and higher primates, uric acid is the final oxidation (breakdown) product of purine metabolism and is excreted in urine." This is also why humans get uric acid kidney stones. Now I should add, however, that I have some personal doubts about the perfect truth of this statement, because urate oxidase happens to have a "stop codon" right in the catalytic site that happens to use the sequence for selenocysteine, though it doesn't have a good SECIS. I have a feeling humans might just use the very low amounts of RNA produced for this gene to make some amount of functional protein for specialized purposes, and therefore can go on from uric acid in some small percentage of the total metabolism. But that's just personal speculation. Wnt (talk) 07:32, 26 June 2011 (UTC)[reply]
Right, the key words being purine metabolism. Humans excrete purine waste products as uric acid, but nearly all other nitrogen waste products as urea. Uric acid only counts for a small amount of human nitrogenous waste (though still enough to cause gout). On the other hand, birds and reptiles excrete nearly all of their nitrogenous waste as uric acid (as a solid, along with the feces). Buddy432 (talk) 03:00, 27 June 2011 (UTC)[reply]
As I was decided to discuss about this subject Ibrought It,here I want to say my idea:
The periodical variation of sun body and its convection ,make the sun to have global magnetic fields outside and inside of its body .the plasma body of sun make it not to be able to have magnetic poles such as earth ,in addition its rotation round its axies has defferenet speeds from equarter to pole.
The major defference between earth magnetic field and sun's one is that earth has iron core and semi stable solid body . but the magnetic fields in sun are the result of movement of electeric particles .akbarmohammadzade--78.38.28.3 (talk) 07:35, 26 June 2011 (UTC)
The solar wind
It is supposed that the solar wind moves direct planetary orbital .but it might be all around any quarter of sun , then we can suppose that the kuiper belt be sphrical round solar system (not ring ).
is it because of Einshtein general relativity that the solar wind have to move in such direction?--Akbarmohammadzade (talk) 05:31, 25 June 2011 (UTC)Iran
Huh? As we read in our article on the Kuiper belt, the belt resembles a torus with the main concentration extending to around ten degrees outside of the plane of the ecliptic. It is not spherical (hence the designation 'belt'). The Solar wind, which I believe radiates in all directions from the star, doesn't really have much to do with its shape as far as I know, though I might be wrong. That's all I could understand from your question. --Ouro (blah blah) 07:03, 25 June 2011 (UTC)[reply]
Indeed, the Oort cloud is spherical. Neither the Oort cloud of the Kuiper belt have anything to do with solar wind, though. --Tango (talk) 13:25, 25 June 2011 (UTC)[reply]
And the radiation of particles, like anything else, occurs in all directions from the source. If the solar wind does push the planets outward in their orbit a bit, I would expect only a tiny effect, and for it not to be cumulative, since the orbital speed ultimately controls orbital distance. Think of it like a fan blowing a ball upward. It only moves up a bit, since gravity holds it down. StuRat (talk) 13:43, 25 June 2011 (UTC)[reply]
The solar wind doesn't have much effect on orbits, but radiation pressure does. It's particularly significant for asteroids. Also, the solar wind isn't going to completely spherically symmetrical because it is affected by the sun's magnetic field, which isn't spherically symmetrical. --Tango (talk) 18:47, 25 June 2011 (UTC)[reply]
well the O'ort belt is far from us , but we can see the effects of Kuiper belt where that first send water here to earth. ( in fact I am studying about the efects of solar wind on production of water in solar system , which cased the existance of life in this system) Akbarmohammadzade (talk 08:52, 26 June 2011 (UTC)
Use of figures from copyright protected references
I am referring to figures which I personally drafted in the first place and which ended up in published articles that I coauthored (e.g., in Journal of Inorganic Biochemistry, etc., not someone else's articles). Is this forbidden by Wikipedia? Figures certainly help to clarify concepts in any review-type article.
A am attempting to write an account of a specific area of chemistry. I see figures used this way in review articles all the time (e.g., page 8 of the Encyclopedia of Vitamin-E used images from a paper I coauthored, which was published in Biochimica et Biophysica Acta. originally). Jrwright72626 (talk) 11:27, 25 June 2011 (UTC)[reply]
Yes, see the help desk in the first instance. DCM may not be necessary; it depends what you mean by 'figures', if, as one might think, you mean illustrations of some kind, then DCM may be necessary. Grandiose(me, talk, contribs) 12:49, 25 June 2011 (UTC)[reply]
DCM probably doesn't apply in this case, since most journal publications require authors to transfer their ownership/copyright of all published material to the journal. Figures that are reproduced in a review article without any substantial changes require the permission of the original journal (that's why it often says "reproduced with permission from ..."). I doubt that a journal would donate their materials to be freely reproduced on Wikipedia, and if a copyrighted image is found in an article it will most likely be removed. If you are interested in contributing figures to Wikipedia, it would probably be best to create new figures and publish them into the Wikimedia Commons so that they can be freely used. --- Medical geneticist (talk) 13:40, 25 June 2011 (UTC)[reply]
While the help desk is the best place for questions concerning using or contributing to wikipedia in general, the best place for this specific question is probably Wikipedia:Media copyright questions, I suspect you may be directed the if you asked at the help desk. Nil Einne (talk) 13:55, 25 June 2011 (UTC)[reply]
Medical geneticist is right -- I should create entirely new figures. I do have some photos and diagrams (of a spectroscopic display, electrophoretic separations, etc.) that have not been published anywhere. Obviously I could use those without having to go through a lot of letter writing. Jrwright72626 (talk) 16:19, 25 June 2011 (UTC)[reply]
Fortunately the US doesn't have database copyright, but for those unfortunately living in countries that do, I don't know if even redrafting a graph would be legal - it might be that the journal claims to own the results themselves. Though I would not criticize someone for posting the data here anyway, nor would I support any effort of Wikipedia to collude in the enforcement of such regulations. Wnt (talk) 21:10, 25 June 2011 (UTC)[reply]
Lasalocid
I looked for further information on this chicken food additive because a local stock food company has just recalled several batches after accidentally adding lasalocid to chicken mash and feed pellets. One of the warnings in their advertisement was that it should not be fed to dogs. I thought this might be a useful addition to the Wikipedia entry.
There are many references to this problem and I have amended the article with an appropriate reference from the Veterinary Record of the British Veterinary Association. Thanks for that Heather, for future reference it is usually better to leave a note like this on the 'talk' page of the article which will bring it to the attention of any watchers of that page. Richard Avery (talk) 10:12, 26 June 2011 (UTC)[reply]
Hi, I couldn't help but compare the data of this event with human impact and climate change. The extinction figures were pretty much as they are today according to the estimates and there was afterwards a huge geological event which began as a *greenhouse effect* and countiniued into a super hot world that even any trace of humanity would probably not survive.
Let's say that at that time an intellegent life form became dominant over the earth causing the extinction event, not dissimilar to the corresponding present figures which are showing massive extinctions that we cannot even explain. Let's say that this civilisation caused a greenhouse effect, much in the way that present day earth is believed to be going. No coal seams are recovered from that time as though something not only made the trees extinct, but also performed the magic of making them disappear as well?
Excerpt:
"This pattern is consistent with what is known about the effects of hypoxia, a shortage but not a total absence of oxygen. However, hypoxia cannot have been the only killing mechanism for marine organisms. Nearly all of the continental shelf waters would have had to become severely hypoxic to account for the magnitude of the extinction, but such a catastrophe would make it difficult to explain the very selective pattern of the extinction. Models of the Late Permian and Early Triassic atmospheres show a significant but protracted decline in atmospheric oxygen levels, with no acceleration near the P-Tr boundary. Minimum atmospheric oxygen levels in the Early Triassic are never less than present day levels—the decline in oxygen levels does not match the temporal pattern of the extinction."
Is it not a good theory that intelligent life evolved and destroyed the planets ecology, themselves with it, and so on from there?
This makes a good sci-fi story, but there are problems. First, I'd think that sentient species at any time would have been fairly likely to invent clay pots, and the broken shards of clay pots should have turned up in sediments somewhere. Next, I'd kind of expect whatever species involved would develop a larger brain, which would be noted as remarkable by paleontologists - and I'd expect their remains to be found, because it's hard to destroy the Earth if you don't have numbers. And when found, shouldn't they have something, some weapon or possessions, some part of the time? Last, how do the Siberian Traps fit into this scheme? It seems as easy to believe that two spaceships were having a war and a stray shot found its way to Earth, creating the Traps and causing all the atmospheric changes. Wnt (talk) 23:56, 25 June 2011 (UTC)[reply]
To answer your question directly. No! it's not a good theory because there is no supporting evidence. The (It's all happened before theory) was popular in the sixties, hence the great thoughtfull song [Year 2525].190.148.136.161 (talk) 00:30, 26 June 2011 (UTC)[reply]
(ec) To get an idea of why it's pretty implausible, consider what the fossil record millions of years from now would look like if humans did end up wiping themselves out due to climate change sometime over the next few centuries. There would be more than a bit of evidence of our civilization: buildings, roads, technology, not to mention the shear scale of the number of humans that would leave their skeletal remains behind. You're suggesting some creatures had a climate impact on the planet on that scale or larger but left no trace at all of their existence. What was all that coal being burned by/for? Rckrone (talk) 00:35, 26 June 2011 (UTC)[reply]
June 26
Hotspot underneath Iceland is the same one that produced the Siberian Traps?
In this article, it is mentioned that the hotspot that produced the Siberian Traps may be underneath Iceland now. But do have have 250 million years of continuous volcanism from today in iceland to the formation of the Siberian Traps, 250 million years ago? Count Iblis (talk) 00:46, 26 June 2011 (UTC)[reply]
The article you cited did not claim that the plume that caused the Siberian trapps is now under Iceland. It said that a gigantic impact in Antarctica may have caused the Sib. trapp by antipodal disruption and incidentally may also have contributed to the Iceland plume. 190.148.136.161 (talk) 01:49, 26 June 2011 (UTC)[reply]
Prehistoric Scotland says that there was a lot of volcanic activity around the Scotland area in that same time period. The Icelandic plume is thought to have migrated N-W. from that area helping to open the North Atlantic.190.148.136.161 (talk) 02:07, 26 June 2011 (UTC)[reply]
It's a bit of a jump to get from the Siberian Traps to the Iceland plume, although in between there is the High Arctic LIP, which was mainly active in the middle to late Cretaceous (so about 100 to 80 million years ago), and the North Atlantic LIP which was active from the latest Cretaceous up to the end of the Paleocene (about 70 to 55 mya). The iceland plume reached its current location in the Mid-Atlantic Ridge by the Miocene (about 15 mya). Some people have suggested [15] following plate reconstruction that the siberian traps are located exactly where the North Atlantic LIP was to erupt some 180 my later, but I'm not sure that this is the view of everyone working on these things. Mikenorton (talk) 18:14, 26 June 2011 (UTC)[reply]
crossing over
If I stood, or sat in my rowboat, at the east side of the international date line (somewhere in the Pacific), and then I stepped or rowed to the other side of the line. Would today now be tommorrow or yesterday? 190.148.136.161 (talk) 00:59, 26 June 2011 (UTC)[reply]
Of course, today is still today on either side of the line. It is simply that our time-keeping convention is to call today Tuesday on one side of the line, and to call today Wednesday on the other side of the line. It's just an arbitrary change of co-ordinates. Gandalf61 (talk) 08:12, 26 June 2011 (UTC)[reply]
It affects business in the South Pacific. When it is Monday morning in New Zealand and Australia it is Sunday morning on some Pacific Islands and the businesses there then suffer. Some Pacific Islands have decided to move one day ahead to deal with this problem. Count Iblis (talk) 17:07, 26 June 2011 (UTC)[reply]
Constitutional walk [close to speed of light] on Einstein’s treadmill:
Although the stepping positions in space would remain same but would the moving clock on such a treadmill be slowed down?
As air time is involved in RUNNING therefore WALK should be considered in the scenario - non-broken connection between walker and walk belt 68.147.41.231 (talk) 03:21, 26 June 2011 (UTC) Eccentric Khattak No.1[reply]
The footfalls all occur at the same location in space according to the racewalker's frame of reference (or really the same two locations, since the racewalker has two feet), but they do not all occur at the same location according to the belt's frame of reference. In the belt's frame of reference, the footfalls occur at the locations of the footprints left behind on the belt, which in the belt's frame of reference are stationary.
The two frames of reference do not necessarily agree as to whether the person is running or walking. The event of a front foot landing and the event at around the same time of a rear foot leaving the belt occur at two different locations, so there's relativity of simultaneity to deal with. I.e., the two frames of reference may disagree as to whether the rear foot has left the belt yet as of when the front foot lands. Red Act (talk) 12:06, 26 June 2011 (UTC)[reply]
Also, unless the belt is moving less than half the speed of light (in the racewalker's frame of reference), walking instead of running would be impossible, because walking would require the feet to move faster than the speed of light. Red Act (talk) 12:41, 26 June 2011 (UTC)[reply]
The person can be walking in their frame no matter how fast the treadmill is going, it just won't necessarily be walking in the treadmill frame. Rckrone (talk) 16:03, 26 June 2011 (UTC)[reply]
How do you define "their frame" for someone walking? Is that the frame of their head? I don't think it is possible to walk (on solid ground or a treadmill) faster than around 0.5c, since your feet need to move faster than your overall speed (in the lab frame) in a walking motion. The same is true of a vehicle travelling on wheels - the top of the wheel moves at twice the speed of the vehicle, so it can't go faster than 0.5c (in that case, it is exactly 0.5c, I'm not sure exactly what the top speed would be for a walker). --Tango (talk) 18:30, 26 June 2011 (UTC)[reply]
A clock attached to the treadmill would obviously run slow relative to a clock on the wall of the room (which I assume is the reference frame the OP is interested it), the fact that someone is running on it makes no difference at all. I don't think that was the question, though. I think the question was whether a clock attached to the runner would run slow compared to the wall clock. If it was attached to the runner's torso, then it wouldn't since the torso isn't moving significantly relative to the wall (that lots of other things are moving really quickly doesn't matter, you just look at the two clocks). If it were attached to one of the runner's legs, then it gets a lot more complicated because the legs are accelerating. At some points they will be moving backwards at relativistic speeds, at some points they will be stationary and at some points they will be moving forwards at relativistic speeds. That means the clock on the legs will run slow compared to the wall clock, but I can't immediately calculate by how much. --Tango (talk) 13:34, 26 June 2011 (UTC)[reply]
The other replies have effectively already said this, but let me emphasize: time dilation only depends on the motion of the clock relative to the lab. It never makes any difference how the clock is "attached" to the lab (via a pair of rapidly moving legs and a treadmill, in this case). Likewise, it makes no difference if it's not attached at all for some of the time (air time). In general relativity, the legs and the treadmill do technically matter, but only because they gravitate, not because they're attached to the clock. -- BenRG (talk) 16:47, 26 June 2011 (UTC)[reply]
To all - Sorry about the confusion!
By “Moving Clock”, I meant light clock [mini model] on the Runner’s head [fixed] not attached to the walk belt. As runner [walker] moves close to the speed of light and so the light clock therefore if time dilates then
Why a pulse doesn’t trace out longer path/ angled for stationary observer in Gym’s frame of reference?
At http://elenin.org/ we read that this comet "follows a 9,900 years hyperbolic orbit around our sun". That seems contradictory. To specify a number of years seems to imply periodicity. But "hyperbolic" seems to imply that it's not periodic. What is meant? Michael Hardy (talk) 04:34, 26 June 2011 (UTC)[reply]
At one Epoch the comet can be hyperbolic, while at another it can be a closed loop. The real orbit (or the best approximation to such) considers perturbations by all planets, a few of the larger asteroids, a few other physical usually small forces, and requires numerical integration. Comet Elenin's orbit will become closed because Jupiter's gravity will lower the eccentricity below 1 as Elenin is leaving the planetary region. -- Kheider (talk) 05:24, 26 June 2011 (UTC)[reply]
Confusion between orbit types is not the most surprising thing at http://elenin.org/. Further down the page, it speculates that Elenin is in fact a brown dwarf and that it will "preciptate major reactions within the Earth's core as well as on its surface that could very well lead to a global catastrophe". Apparently it is connected with the Nibiru collision theory and the whole 2012 "end of the world" thing. Gandalf61 (talk) 08:06, 26 June 2011 (UTC)[reply]
It is often said that Adamantane is the smallest molecule that technically, can be called a diamond. Is it really so, since it contains no carbon only moeities? I suggest a new basic diamondoid (SMILES): C1C2CC3CC1C14C5CC6CC(C5)C57C8CC9CC(C8)C3(C3CC1CC5C3)C47C269. A similiar case exists for Lonsdaleite, where its basic unit is bicyclo[2.2.2]octane. New basic Londsdaloid: C1C2CC3CC4CC5CC6CC7CC8CC9CC1C81CC8CC24C1(C57C8)C369. What are the major differences besides their size and mass? Plasmic Physics (talk) 04:41, 26 June 2011 (UTC)[reply]
I guess it depends on what you think the essential nature of diamond is. Is it being just carbon, or is it being a lattice of singly-bonded tetrahedral carbons? If you're single bonded tetrahedral carbon, you're going to have edge effects, where you cap the carbon with something else (like hydrogen). The question is how far in you allow the edge effects to penetrate. For example, for Adamantane, it's all edge. I would say that Adamatane *does* have a carbon-only moeity, which consists of the ten carbons bonded together. Yes, it's directly connected to hydrogens, but why should that matter? If you're just looking for an all-carbon moeity with tetrahedral structure, why doesn't neopentane count? Or 1-methyladamantane? -- 174.24.222.200 (talk) 18:20, 26 June 2011 (UTC)[reply]
Well, I didn't choose them, because neopentane is non-reprasentative of a singular allotrope; and I chose the ones I did because the central carbon forms closed hexagons with all four adjacent atoms, meaning at it contains five carbons which are only attatched to other carbons. That is what I meant by carbon only moeities, appologies for the confusion. Plasmic Physics (talk) 20:35, 26 June 2011 (UTC)[reply]
what is un-saturated polyester film
Dear Sir,
As per subject given up Kindly clearify my that what is diffrence between saturated and un-saturated polyester film . This question is asked because of in international harmonized code 3920-6310 of about polyester film which film shall applied for this code its not clear as fo as you are requested to please clerifiy me about diffrence between saturated and un-sturated polyester film and for which purpose these film shall be used.
See Polyester and Polyester resin. Unsaturated polyesters are resins, generally used in structural applications (as "fibreglass"). I don't think it would be possible to make a _film_ from resin, so anything described as "polyester film" will almost certainly be made of a saturated polyester. Tevildo (talk) 11:27, 26 June 2011 (UTC)[reply]
Orbital speed and escape velocity
My book on physics says: "The higher the [circular] orbit of a satellite, the slower its speed and the longer its period." But it doesn't say anything about why this is so. My reasoning is that the escape speed farther from the earth is lower, so the speed of the satellite also needs to be lower, otherwise it won't stay in its orbit but escape. Is my reasoning correct? Lova Falktalk09:50, 26 June 2011 (UTC)[reply]
Sort of. A better way to look at it is in terms of centripetal force. The centripetal force is the force that keeps the object on a circular path, in this case that is gravity. That article gives us a formula for centripetal force: F=mv2/r (r is distance from the centre of the orbit, m is the mass of the object and v is its velocity). If you equate that to Newton's Universal Law of Gravity, F=GMm/r2 (M is the mass of whatever it is orbiting and G is the gravitational constant) and rearrange, you'll get v2=GM/r. That shows that as r increases, v decreases. That the orbital period will increase is obvious - it's travelling a longer distance at a slower speed, so it takes longer. --Tango (talk) 14:35, 26 June 2011 (UTC)[reply]
Looking for a good Scientific Paper
about the PRINCIPLES of the Imprinting phenomenon of Konrad Lorenz.
I'm not sure what "principles" means, but in any case Google Scholar is often a good resource for digging up information of that sort. You can find a downloadable pdf of a 1958 Scientific American article here; or if you are looking for something more recent, this is a paper from 2011 that briefly describes the current state of the art. There is lots more available; the literature on that phenomenon is very extensive. Looie496 (talk) 17:11, 26 June 2011 (UTC)[reply]
Subterranean rivers
The concept of subterranean rivers somehow makes me feel as if I'm thinking about strange creatures from mythology, and I wonder if that's because I've found rather little information about them. Here we see one of a number of places in the Minneapolis/St. Paul area where such a stream emerges from underground at a point along the banks of the Mississippi River; at each such point there's a waterfall because the riverbanks in that vicinity are steep and high. From this map it looks as if this stream must flow under the campus of the University of St. Thomas. Obviously the locations of such things must be taken into account whenever a building is built on the land above it.
Where can I find maps of subterranean rivers in specified areas (Google Maps doesn't immediately give me those).
If the mental picture you have is of an empty tube, filled with water, like a pipe or tunnel, that's extremely rare. Groundwater emerging from the terrain is almost always the outflow from an aquifer. Very occasionally, in the right circumstances, there can be flooded caves, but that's very rare. Anyone planning any building of reasonable size will perform a geotechnical survey which will determine the technical nature of the soil and the character of the water table (and other local hydrology) and will design the building's foundation accordingly. -- Finlay McWalter ☻ Talk19:49, 26 June 2011 (UTC)[reply]
In cities it's not uncommon for natural rivers to be put into culverts and then built over, such that they become effectively subterranean rivers (see Subterranean rivers of London for some examples). It's mostly a matter of nomenclature whether these are really rivers or just drains. -- Finlay McWalter ☻ Talk20:01, 26 June 2011 (UTC)[reply]
@Finlay: I don't think you would suspect that the stream in the map I linked to had been artificially put underground if you saw it close up.
Here's another one, maybe a mile and a half upstream from there. The stream flows out of the vertical face of a cliff maybe 30 feet below street level, and looking around you would see that the waterfall has been carved out over many centuries. Michael Hardy (talk) 22:11, 26 June 2011 (UTC)[reply]
Yes, but it could still be water flowing out of porous rocks, as opposed to a tube. If you fill a keg with sponges and water, then open the tap, water will flow out, but have you created a "river" ? StuRat (talk) 02:29, 27 June 2011 (UTC)[reply]
Gold is a chemical element, so it will have been created in a supernova and will have been essentially unchanged ever since (gold rarely even bonds with other elements in compounds). Some of it may have come from the radioactive decay of other elements, but I believe that is a very small proportion. Meteorites, on the other hand, are lots of compounds stuck together. Meteorites will have formed during the early period of the formation of the solar system, which was some time (ie. millions, maybe billions of years) after the supernova that seeded the solar nebula with heavy elements. --Tango (talk) 21:27, 26 June 2011 (UTC)[reply]
(edit conflict)Your question really is asking to compare apples to oranges. A meteorite is defined as any extraterrestrial object, whether rock or metal, that has fallen to the Earth's surface. These have been falling to Earth since its formation, and many of the meteorites that fall are remnants from the early solar system before the earth was formed, but technically they are not meteorites until they land on Earth.
Gold, on the other hand, is an element; it is formed in the heaviest stars as they turn to supernovae. Gold we find on Earth was formed as stars exploded over and over during the billions of years before the formation of our solar system. Thus, in the strictest definition, you could say that gold is "older" than meteorites, but again, it is not really a good question to ask. Some meteorites may even contain gold. -RunningOnBrains(talk)21:36, 26 June 2011 (UTC)[reply]
I'd say almost all gold on Earth is older than meteorites on Earth, having been created by supernovae before the formation of our solar system (and thus before any meteorites here), but there could be some more recently created gold that drifted into our solar system and fell to Earth since it formed, and therefore could possibly be newer than some terrestrial meteorites. Also, gold can be created as the end product of radioactive decay, so there might be some newer gold from that source. As for the broader question of gold versus meteorites throughout the universe, that's a different story. I would think there were many meteorites prior to the first supernova, so they might win, in that case. StuRat (talk) 02:21, 27 June 2011 (UTC)[reply]
Yes, this downloadable paper from 2007 directly addresses that question, and its introduction reviews earlier relevant literature. The results "show that the diagnosis of ASD is pertinent when individuals are prosecuted under stalking legislation in various jurisdictions". I will leave it to you to figure out what that means. Looie496 (talk) 02:06, 27 June 2011 (UTC)[reply]
Would it be scientifically accurate to say that by having a child, I am perpetuating 3.5 billion years of successful reproduction, and therefore extending a 3.5 billion year long lineage by one generation? The Masked Booby (talk) 02:49, 27 June 2011 (UTC)[reply]
Please do your own homework.
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