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.
I don't know, but would caution against mixing your own chemicals, since some combos, like chlorine bleach and ammonia, can produce toxic gases. I'd just use diluted ammonia for window cleaner, since it works well without the alcohol. StuRat (talk) 02:30, 15 July 2008 (UTC)[reply]
first it should be bo problem to mix IPA with ammonia because we will say their tendency is base both. but be careful for the ammonia, its odor and vapor is quite irritated, with eye and nose especially.
second if to clean glass I would recommend any alcohol is enough, most glass cleaning agent formulated from butyl cellosolve. anyway try a litlle first with coated glass eg. computer monitor, TV which claimed coating something on screen to protect your eyesight. the coating may be peeled off.
for me, water with drop of dish washer is perfect to clean glass.........ninjaw
Hemispheres
s it true that due to Earth's rotation, water and air masses turn in different directions in both hemispheres. For example, if I am draining water from a sink in Sydney, would the water really rotate clockwise but in Los Angeles, it would rotate counterclockwise? What is the source of this phenomena? Do we have an article on this? Can someone perhaps shed some light on this?--A Real Kaiser...NOT! (talk) 06:27, 15 July 2008 (UTC)[reply]
This has always interested me, since childhood (and unlike the poster in a thread above, no we don't all time travel into the future one year per year, I've remained stuck in little kid mode!) when I would sit in the bathtub and twirl the draining water backwards - it would always go back into clockwise rotation, basically obeying the right-hand rule. Is it at least generally true that everything drain-wise we commonly see in every day life spins clockwise? Does anyone have a counter-example? Southern hemisphere 'pedians are welcome to post, but please type backwards.
I've always been curious about the no-Coriolis explanation - why do businesses design right-hand bathtubs? These are the questions that plague me :) Franamax (talk) 06:50, 15 July 2008 (UTC)[reply]
Well I just filled my sink and let it go...it made a nice counterclockwise cyclone even though I'm in the northern hemisphere :-p Someguy1221 (talk) 07:25, 15 July 2008 (UTC)[reply]
In the northern hemisphere, the Coriolis effect applies a small tendency to rotate draining water counterclockwise. This is the reason low-pressure weather systems rotate in that direction north of 0 degrees. --Bowlhover (talk) 07:39, 15 July 2008 (UTC)[reply]
Hmm. I get kitchen sink = clockwise, bathroom sink - didn't work 'cause of the plug thingy, bathtub = clockwise (after I found the plug, I only take showers). My family and friends are going to think I'm a bit weird when I visit them over the next few weeks and puddle around their houses :) I do recognize the paradox vs. the Coriolis effect and I'll stop when I find a ccw drain, honest. Otherwise, Someguy will have to mail me their sink. Ahh the unsolved mysteries of childhood - thanks all for the input! Franamax (talk) 21:50, 15 July 2008 (UTC)[reply]
I don't know about bathtubs, but I've certainly seen water in drains rotate in both directions, as well as water in toilets. The direction of water in any specific toilet, though, is constant because the water used to flush it is injected in the same way every time.
In a system as complicated as the human body it is difficult to say without more details. (Standard Wikipedia Disclaimer: The reference desk does not offer medical advice.) The interdependencies and what ties into what within a living organism, particularly a set as complicated as mammals. If you're really concerned about it, my first guesses would be a drug interaction, possibly between any anesthesia you were given and any other medication you were taking, or depending on how invasive the procedure it is possible there was nerve damage. You also mention infections, and given the proximity of your mouth to your central nervous system I suppose it might be possible the infection traveled. Take the above with a grain of salt, as I'm not an expert, but my short answer to your question would be, "Yes, anything is possible. If you've had any kind of weird changes in your medical condition after a procedure, see a doctor." EagleFalconn (talk) 13:06, 15 July 2008 (UTC)[reply]
I'm confident that the answer is "No" directly, but "Yes, possibly" indirectly. Dental surgery could, like any other surgical procedure, allow infections to take place which may then cause loss of sight. As EagleFalconn also said, there is also the possibility of drug interaction or nerve damage. I'm going to take a guess that you are concerned about either your or someone else's loss of vision since this is the second post you have made regarding loss of vision. I really suggest you ask a physician if you are concerned because honestly, they won't bite. — CycloneNimrodTalk?20:36, 15 July 2008 (UTC)[reply]
I can't see how it looks like a stink bug (or shield bug in UK) The mystery beetle had a separated head and it is about twice as long as it is wide. The stink bug has the head joined directly to the thorax and is about about as long as it is wide. I find it hard to disagree with your initial phrase EF. Richard Avery (talk) 13:52, 15 July 2008 (UTC)[reply]
To be honest I agree with you, I'd always wondered why they were called stink bugs. I'd never experienced any particularly putrid odors. My guess is that its a regional misnomer, but the snide remark wasn't really necessary. EagleFalconn (talk) 14:27, 15 July 2008 (UTC)[reply]
The BBC link mentions that it looks similar to arocatus roeselii. In my opinion they look so similar that I would bank on it being one of them. Wikimedia Commons has an image which is labelled as arocatus roeselii. See below. Very close likeness of the markings. Arocatus roeseliiRichard B (talk) 14:35, 15 July 2008 (UTC)[reply]
Just so we're clear where the confusion lies (come on, does anyone here really think they can out-classify the London museum of natural history? Especially given that we're just working off of a single image from an article, and they have live samples), from cnn.com:
“
The bug resembles the Arocatus roeselii, which is usually found in central Europe but is a brighter red and lives on alder trees.
Entomologists suspect that the new bug could be a version of the roeselii that has adapted to live on plane trees but acknowledged that it could be an entirely new species.
According to this Snopes article, sugar is insoluble in gasoline and cannot even reach the engine. Instead, it's blocked out by two filters specifically designed to keep contaminants out of the engine. --Bowlhover (talk) 08:42, 15 July 2008 (UTC)[reply]
The Straight Dope also discussed this as an SD Staff Report, and indicated that it would, in fact, be bad for the engine. When objections surfaced along the lines of the Snopes article, they tackled the question again and came to the same conclusion, this time after conducting an experiment. (It apparently didn't ruin the engine, but certainly put it out of commission for the time being.) -- Captain Disdain (talk) 11:54, 15 July 2008 (UTC)[reply]
A note of clarification. Both the Snopes article and the Straight Dope article suggest that while a large quantity of sugar in the gas tank could immobilize an automobile, it has nothing to do with any direct effect on, or harm to, the engine. Rather, the accumulation of gasoline-insoluble sugar is apt to clog up the 'sock' or the fuel filter, starving the engine for gasoline. TenOfAllTrades(talk) 14:02, 15 July 2008 (UTC)[reply]
For a more general answer - everything2 is not considered a reliable source by wikipedia's policies, and it is a site that anyone can sign up and add content to, so you probably could not use this as a source e.g. if you were to write a paper. It may be worth your time to check out the sources that it lists at the bottom though. --Random832 (contribs) 18:24, 18 July 2008 (UTC)[reply]
Can one person create the sound of a barber-shop quartet?
I watched a cartoon recently where one of the characters sings a song in the style of a barber-shop quartet i.e. 4 harmonised tunes all sung together.
This got me wondering. Is there any physical reason why a single person couldn't produce the sound of many notes (e.g. a chord or a harmonised tune) using only one voice? Presumably, if a single speaker connected to an amplifier can play music comprising many different notes and instruments at one time, a human's vocal chords can do the same? Could someone train their voice to do this?
Beyond the specific and limited capabilities of throat singing, though, I'd say the answer is No. A typical speaker can produce arbitrarily complex waveforms, because it's constantly driven by a magnet, which pushes air in whatever pattern is encoded in the signal. The voice, though, is closer to a musical instrument, with a single vibrating surface to generate the sound, driven by resonance when wind is passed over it. You're not singing by actively vibrating your vocal chords; you're pushing air over them, which makes them vibrate. You can vary your throat shape to accentuate harmonics, but I would think you can't make completely independent sounds. jeffjon (talk) 15:06, 15 July 2008 (UTC)[reply]
More precisely, tenor, lead, baritone, and bass. Lead is roughly a second tenor, but is not called a tenor. It's not impossible that one person with a large range could sing all of these -- actually a lot of barbershop tenors are natural basses, because barbershop tenor is normally sung falsetto.
Barbershop baritone is one of the most thankless roles you can imagine -- it's extremely difficult, because you're typically on the third or the seventh, but no one hears you because you're in the middle of the chord and don't have the melody. I'm a natural baritone, but sang lead because I don't have a good enough ear for barbershop baritone. --Trovatore (talk) 07:23, 16 July 2008 (UTC)[reply]
i note that the graph on that page is oxygen/time (essentially calories per time) vs velocity. since the OP asked about calories per distance, that turns out to be the slope of the graph. now, the slope of the graph for walking up to the point where running starts and the slope of the running graph after that is about the same, indicating that in fact the calories used per distance is about the same whether running or walking, if you don't try to walk at an unusually rapid speed when you would more naturally be running. this agrees with what i've heard elsewhere, which is that calories per distance for a human is essentially constant with velocity except at very high velocities, and also at very low velocities, but that's just because the 2000 calories a day you need for your basic metabolism becomes significant. this also makes sense evolutionarily, where efficiency would be something that would be selected for, except at war emergency power life or death speeds. but of course, arguments from evolution can be used to support either side of an argument if you're clever. Gzuckier (talk) 19:47, 16 July 2008 (UTC)[reply]
about "some naive hypothesis at odds with basis of physik "
1--Can i have page history from july o9 08 till july 15 08 ?
2--It was my mistake that part of my writing above subject is not edited ? I am new user. I wrote three hypothesis: I- About a hypothetic particle that supposed to be the only basis component of common particles. II- About some " corrections" in the formula of Lorents-Ajnstain. III- About the gravity charge as +,- f^0.5 (That is +,- G^0.5 ). This charge together with electric charge supposed to be the only forces in equilibrium in ten kind simple common particles. They (Hypothesis)are naive because are not supported by sophisticated math. It used an simple math because the writer is illiterate on high math, so in physic.
But they are controversial with basis of contemporary physic, linked together to prove that no-thing can be created by nothing,that the supposed unique particle can not be created can not be destroyed, that the annihilation of matter is a wrong concept and the photons are common particles ( structured by the same unique particles.) which for outer frame are both electric and gravity null charged .
The user hoped that any bright lad or lads will find interesting the meaning of the hypothesis to search further and fill the lots of gaps. 70.248.135.115 (talk) 17:56, 15 July 2008 (UTC)[reply]
Just click "history" at the top of the page on any page in Wikipedia to get the history of edits to the page. Click on a version number and you'll see the page exactly as it was on that version.
Wikipedia is not a place to post your original work and ask others to critique it. It is a collection of references from published, respectable resources. You appear to be in need of a message board specializing in physics - and one specializing in basic English grammar. -- kainaw™18:02, 15 July 2008 (UTC)[reply]
Why don't leaves form a thin layer like a bag over a tree?
I was struck going under some trees by how many branches they had with leaves all higgley piggledy up the trunk with one lot of leaves covering another and gaps all over the place. I would have thought the most efficient form would have all the branches extending out about the same amount with the leaves at the end forming a sheet facing out. I'm sure it wouldn't be difficult to evolve that way if it were actually best, but if you look under tree you'll see they are nothing like that. Why aren't trees more like that? Dmcq (talk) 18:37, 15 July 2008 (UTC)[reply]
This is going to sound really snarky, but a short answer would be because intelligent design is probably wrong. That is to say, you're correct, that probably would be the most efficient arrangement. However, as you correctly identify, evolution has not yet favored that particular growth pattern. Its almost assuredly not impossible. In fact, its even possible that trees are approaching that kind of an arrangement. But they have to get there incrementally. Also, its entirely possible that the dome shape you imagine is not the most efficient, possibly for reasons of what the other trees in the area are shaped like (and therefore what spaces are available) etc. EagleFalconn (talk) 19:00, 15 July 2008 (UTC)[reply]
Thanks everybody for the replies, lots of ideas there. Nothing I could even begin to thinking of doing something like running a simulation with, especially by intelligent design I'd have to be God to be really sure my design was intelligent! I guess trees are quite different from each other so there can't be a unique best solution. On the point of whether tree have had enough time to evolve this, if you have a look at umbel you'll see something like what I was thinking about for flowers but even small plants don't seem to do this with their leaves. By the way the picture on the right of the carrot flower directly contradicts the text about the stalks being the same length. ;-) Dmcq (talk) 21:45, 15 July 2008 (UTC)[reply]
A dome would have gaps between the leaves, by having a three dimensional arrangement you fill in those gaps. There are certainly more efficient arrangements, but presumably they don't offer a large enough benefit, or have some downside, so trees haven't evolved that way. Trees have been around for 100s of millions of years, I think evolution would have achieved an optimal arrangement of leaves by now if such an obvious one existed. --Tango (talk) 19:28, 15 July 2008 (UTC)[reply]
Be interesting to know what the downsides might be. Perhaps it isn't best for leave to be in full sunlight and the top leaves are sacrificial to some extent, but then I guess they'd flop around or droop or something like that Dmcq (talk) 21:45, 15 July 2008 (UTC)[reply]
Trees probably don't grow according to centralized planning. Each little part of the tree is probably given a little autonomy in adapting best to its particular conditions. So you get something that looks a little irregular but is obviously efficient enough to work. That's all evolution gives you: just enough to work and not get totally out-competed. Anyway, your assumption about what is "optimal" is contingent on a number of assumed conditions about the particular light the tree could get, the spacing of trees between one another, wind conditions, the "cost" to the tree in terms of generating leaves, etc. I'm not sure your design would be ideally optimal in all conditions (and the question of how the tree would "know" how big to make each branch also probably introduces some sort of need for an energy-intensive feedback system as well). --140.247.241.142 (talk) 19:32, 15 July 2008 (UTC)[reply]
This answer and the next seem to directly contradict each other as to a cause to get the same result! And I can't make my mind up as to which one sounds more probable. Yes the individual leaves probably do compete with each other. And yes the whole tree might benefit and so be more successful if leaves cooperated in letting light through. I tend a little bit more to the former. As to a feedback system for knowing how much to grow and when to stop - tat would be fairly straightforward I'd have thought. Just keep growing whilst the light flickered a lot.~~
The sun moves.. Leaving gaps between the leaves means that leaves on the far side of the plant still receive light even when the light comes from the other side.. Also the wind moves the leaves around meaning that this sort of built in margin for error is useful.87.102.86.73 (talk) 19:51, 15 July 2008 (UTC)[reply]
See last question and answer, this assumes it is in the best interest of the tree to share the light around. I'm not ure that is right becaue it also allows light to fall below the tree and o allows compeitors to grow.Dmcq (talk) 23:21, 15 July 2008 (UTC)[reply]
Not sure the shape has anything to do with being efficient at using resources to gain energy from the sun. More like cutting down the problems caused by the sun.Dmcq (talk) 23:21, 15 July 2008 (UTC)[reply]
Yes, very interesting. They are much more like what I was thinking of. However they use up an awful number of branches to achieve the effect. Less branches with ends that opened out like the picture on the right in the article on umbels to hold the leaves would enable them to grow bigger with less expenditure on branches I'd have thought. Dmcq (talk) 23:21, 15 July 2008 (UTC)[reply]
The shape of a tree is a compromise between many different factors. A spherical tree such as a cactus is best for water retention, but this comes at a cost in photosynthesis efficiency (half the surface is shaded at all times). Big leaves are great for gathering sunlight, but are highly flammable, succeptible to wind damage, and leak water like a sieve. Pine needles are wind-resistant, burn without generating much heat, and are fast to regrow after a fire, but don't gather much sunlight.
It's funny that pine grow more in cold conditions if their leaves are bad at collecting sunlight. Trees seem to be just plain ornery. Dmcq (talk) 23:21, 15 July 2008 (UTC)[reply]
Like I said, it's a compromise. Pine needles aren't that great at gathering sunlight, but they are easy to replace, they burn without damaging the tree much, they aren't damaged by high winds, and they shed snow easily. A big-leaf tree might gather more sunlight, but that doesn't help much if the leaves get ripped off or burned on a regular basis. --Carnildo (talk) 22:53, 16 July 2008 (UTC)[reply]
There is no single "best" tree shape. Evolution ensures that any given tree species is near-optimal for its enviroment, but the wide range of environments and the number of different ways of responding to them means that there are many different shapes for trees. --Carnildo (talk) 22:28, 15 July 2008 (UTC)[reply]
Who knows? Perhaps there is a best tree shape or at lease a very much more restricted number of shapes that are optimal for their conditions than are anywhere near what happens in nature. I don't think I'm anywhere near perfect and yet evolution designed me (Go on, contradict me. No - oh well!). I guess the question I put does go somewhat towards asking what is an efficient tree shape, after all my thoughts about that were obviously wrong. Dmcq (talk) 23:21, 15 July 2008 (UTC)[reply]
Building on the answer above that they may just not have had time to evolve a shape like I was thinking: Fractal shapes can give something that looks like a tree, perhaps the answer that they are good enough for the job because they only compete with other trees is right, and they just haven't the need or maybe even the capacity to develop enough additional complexity to be other than a simple fractal. Dmcq (talk) 23:21, 15 July 2008 (UTC)[reply]
I think a big part of it is that a sphere may not be as effecient as you think. A sphere is effecient for containint volume and MINIMIZING surface area. It's in the benefit of the plant to maximize the surface area (and therefore the number) of leaves facing the sun. Also, by having a broken, tiered surface as most trees have, light gets to almost all sides and levels of the tree at any given time, so every area that needs food (for the most part) gets it. If it was just a big bag of leaf material draped over the tree, the further one gets from the equator the less light would be received by the tree: a large section of leaves would never see direct sunlight because of the earth's tilt. Of course, as 87.102 pointed out, with all the diversity in the world, there certainly are plants that sort of fit your idea. --Shaggorama (talk) 12:08, 16 July 2008 (UTC)[reply]
Well, more than one leaf facing the same direction when one leaf is occluding the other doesn't really give the tree the benefit of the full surface area of each; what needs to be maximized is the total amount of light being absorbed by the leaves. A single "bag of leaf material" would be easily torn by wind; with multiple layers the inner layers wouldn't be self-sustaining, so we have the present "design" as the most effective compromise. --Random832 (contribs) 17:01, 17 July 2008 (UTC)[reply]
I think we need to not imagine a lone tree on a hilltop, but a young tree trying to establish itself in the middle of a forest. A dome would be inefficient in that scenario. APL (talk) 13:02, 16 July 2008 (UTC)[reply]
there's also an ecological/evolutionary component. i.e. (as i was taught, can't verify it from my experience) trees which grow in dense forests tend to have a canopy of leaves which grab all the light, for purposes of competition. if they don't, another tree will, leaving them in the dark. on the other hand, trees which tend to grow less densely tend to have canopies which let much more light through, because any advantage to the individual tree is overshadowed by the advantage to the tree's progeny growing near the parent of getting some light through. this was supposed to explain why some leaves are so serrated, etc., and why some are huge elephant ear leaves and some are just little things. Gzuckier (talk) 19:33, 16 July 2008 (UTC)[reply]
Wind damage can take out whole limbs, as can a number of other factors. Leaves can be eaten away by anything from giraffes to bugs. It makes sense for a tree's branch structure and leaves to take on forms that can survive the whatever is likely to cause damage. The human body, likewise, seems to have all kinds of redundancy. Pfly (talk) 05:04, 17 July 2008 (UTC)[reply]
I had a look at forest and the trees there didn't seem to have a flat top unlike what I would expect. But having a look round at other trees under baobab and cypress there are lone trees with the sort of flat top I would expect in a forest. The dragon tree is more rounded at the top, the start of quite a good dome shape. It has quite thick branches though. The wind damage idea sounds interesting, I guess there might be less wind resistance with gaps for the wind to go through so branches an be thinner. Dmcq (talk) 10:54, 18 July 2008 (UTC)[reply]
Constructal theory might have shown that the branching needed to make the proposed tree would make for inefficient transport of water from the roots. This is just one of a myriad of fascinating factors which seem to influence trees, thanks for a great question! EverGreg (talk) 21:58, 21 July 2008 (UTC)[reply]
wearing glasses
while wearing glasses may help a person suffering from myopia by focussing rays from objects on the retina, wont it alter the relative distance of the object from the eye? for instance an object at infinity will appear to be at the focal point of the lens. so do objects appear closer/further than they actually are?
59.180.19.237 (talk) 20:43, 15 July 2008 (UTC)[reply]
As someone who wears glasses for somewhat severe nearsightedness I can tell you that it takes about a day or two to get used to the change in depth perception caused by a stronger prescription. During those one or two days I find myself reaching for things about an inch closer than they really are.
Per APL, objects do indeed appear to be in the 'wrong' place in space—at least, at first. The brain very rapidly adapts to the 'distorted' view, and you can start to confidently reach for your pints once again. I don't have a link for you, but studies have been done involving the use of glasses which deliberately distort vision (including going so far as to invert vision: [2]). Depending on the degree of distortion, subjects were able to perform tasks relatively normally after a period of acclimatization (hours or days). The brain is quite adept at integrating the feedback from the body's musculoskeletal system with vision information to build a consistent internal model of reality. TenOfAllTrades(talk) 21:18, 15 July 2008 (UTC)[reply]
thanks. but what i dont understand is, in the case of a diverging lens, the image is always formed between lens and focal point(am i right?)-so even very far off objects will appear to be at the focus. so does that mean that people wearing glasses perceive everything to be within the focal length of the lens?
59.180.73.240 (talk) 04:44, 16 July 2008 (UTC)[reply]
effectively yes, I think you're right - this is true for people with short sight - and the image should be within the range in which they can see ie near things.87.102.86.73 (talk) 11:12, 16 July 2008 (UTC)[reply]
It sounds like you have been studying optics, particularly thin lenses - so that's good. Just a small misunderstanding I think. Keep in mind, the lenses in our eyes take incoming light and focus it onto the retina. The image distance is always the distance between the lens and the retina - so pretty constant. The way we do this is by changing the shape (and thefore the focal length) of our lens. For many people, our lenses do not quite focus the light correctly and the light is focused too soon or too late. That is why corrective lenses are used, they cause the light to be focused directly on the retina. If the eye tends to focus the light too early, we use diverging lenses to spread it slightly so it focuses later, etc. So objects don't 'appear' to be hovering at the focal point of the lens in front of us anymore than the original object does. The image is not in front of us - it is on our retina. Hope this helps. PhySusie (talk) 11:23, 16 July 2008 (UTC)[reply]
I think what you're looking for is virtual image. On a slight tangent from the question, I can't find a source for this but an experiment was once described to me where a group of people were given glasses that inverted their visual field, and after a day or two they all adjusted so that when the glasses were removed, they saw everything upside. The brain's a neat thing/ --Shaggorama (talk) 15:53, 18 July 2008 (UTC)[reply]
July 16
astronomy
our solar system is laid out like a plate is it likely that the planets are spin offs from our sun at its birth
dose the sun rotate ?
what is the cause of gravity?
why do the planets rotate anti clockwise? Why do planets revolve around the Sun anti-clockwise?
what is the force that makes the planets travel along the same path around the sun with the same speed all the time ?
do all the stars which are suns all have planets?
where in the milky way is our solar system located?
these questions have been something i have been wondering about for sometime.
If you make even the feeblest attempt at finding these answers yourself, others will be happy to fill in any gaps in the information already easily available throughout Wikipedia. -- kainaw™03:22, 16 July 2008 (UTC)[reply]
I'll bite. Quick and simple laymans answers. For more detailed answers, checkout the relevant articles.
The planets were formed from the accretion disk that surrounded the proto-star that eventually became our sun.
Yes.
General Relativity explains gravity. Any object that has mass, will make a dent in space-time. The larger the mass, the greater the dent. The greater the dent, the greater the force of gravity.
Because of conservation of angular momentum. When the solar system was formed, the accretion disk was spinning in that direction. Venus spins the other way because a massive asteroid collided with it, and changed its rotation direction.
Szeretetelchak, your curiosity is to be commended, but your questions betray some hidden assumptions, which you need to examine more closely.
"Our solar system is laid out like a plate ..." - is it really ? Although the orbits of the major planets lie approximately in the same plane, there is much more to the solar system than the planets. For example, the outer Oort cloud, which contains contain several trillion individual comet nuclei, is spherical, not "plate shaped".
"What is the cause of gravity ?" - simple answer is mass, but this begs the question "What is the cause of mass". Answer that one, and you are in the running for a Nobel prize (unless Peter Higgs beats you to it).
"Why do the planets rotate anti clockwise ?" - there are two misconceptions here: (1) the sense of rotation depends on where you are looking from and (2) even looking from one direction, not all of the planets do rotate in the same sense. But you may be confusing rotation with orbital revolution.
"What is the force that makes the planets travel along the same path around the sun with the same speed all the time ?" - a planet does not travel with the same speed all the time. Aristotle believed this, but he was wrong - see Kepler's laws of planetary motion, especially the second law. And a planet does not even retrace exactly the same orbit relative to the sun, due to orbital precession.
"Where in the milky way is our solar system located ?" - the solar system is not located at a single place in the Milky Way - it is travelling at a speed of about 220 km/s relative to the Galactic Centre, and it has complete about 20 orbits around the Milky Way since it was formed. It is more meaningful to think about the characteristics of the solar system's orbit within the Milky Way.
Anyone know what's happening here? The raptors don't actually seem to be seriously trying to kill each other (with that beak, it wouldn't take long to inflict a fatal wound) - one just seems intent on pinning the other to the ground and keeping him/her there. --Kurt Shaped Box (talk) 06:56, 16 July 2008 (UTC)[reply]
Take note that most animals do not try to kill other members of their own species. Animals that happily and routinely kill other species are usually much more likely to intimidate or submit when among their own. (Humans are often an exception to this.) --140.247.240.177 (talk) 20:02, 16 July 2008 (UTC)[reply]
Outside of military/politically-motivated/gang/revenge situations (what I would refer to as 'violence with purpose'), the vast majority of humans scraps and scuffles have a non-lethal conclusion. Take your typical post-bar-closing scraps. Statistically, very few result in one human beating another human to death with his/her bare hands (obviously, all bets are off when guns and knives come into play). No, the battle seems to end when one combatant is a bloody, broken mess and unable to continue. It takes more will than most people posses to continue to beat and kick a man once he stops moving... --Kurt Shaped Box (talk) 23:59, 16 July 2008 (UTC)[reply]
Size of the Internet
What's the size of the Internet? Number of gigabytes sent/stored, number of computers used, number of human users, amount of power consumed daily, etc? —Preceding unsigned comment added by 24.7.54.224 (talk) 08:43, 16 July 2008 (UTC)[reply]
An interesting question, I expect there is not going to be a precise answer but I'm sure others at this desk will be able to come up with something. In terms of human users, the article Demographics of the Internet may be of interest to you. Jdrewitt (talk) 09:28, 16 July 2008 (UTC)[reply]
Google is said to process over 20 petabytes (20 million gigabytes) data per day. Obviously, this doesn't really help a lot in getting stats about the internet as a whole. Still darn impressive, though. -- Aeluwas (talk) 11:07, 16 July 2008 (UTC)[reply]
The problem is that the internet is a system, not a thing. Every computer connected to the internet is, for that time, part of the internet. Computers connect/disconnect all the time. This question is similar to asking "How many people are in McDonalds?" It cannot be answered because the number of people change every second of every day. -- kainaw™11:47, 16 July 2008 (UTC)[reply]
But you could do a reasonable Fermi estimate to get in the right order of magnitude. Just because something has regular fluctuations doesn't mean it isn't mostly stable to a certain degree of accuracy. The population changes every day but we still have a census that is meaningful. --98.217.8.46 (talk) 14:06, 16 July 2008 (UTC)[reply]
One of the differences here (and in the McDonalds case) is that the change is likely not close to being constant. Americans still make up a big percentage of internet users despite rises in China etc. And people in developed countries probably have bigger hard drives and more data in general then those in the developing world, probably more power hungry computers (although hard to say given the recent move towards energy efficiecy). Therefore, at peaks times for American connection your going to get a large increase in the overall in the data content. I suspect weekends have even more (on the other hand, businesses are more likely to have their computers offline on the weekends and at night time). Similarly in McDonalds, people don't tend to eat at all hours of the day. And I suspect Americans make up a big percentage of McDonalds customers. The number of people in McDonalds in the world, at say 5-8 p.m. (in the various timezones) in the US is going to quite a bit higher then at 3 a.m. in the US. Again weekends and I suspect public holidays are going to be even higher. While I have no specific evidence, my gut feeling is both the data and particularly the number of people of McDonalds at any given time in a day can vary by a large percentage (say 95%+ for McDonalds) and obviously by even more when we consider over the various days of a year. On the other hand, I suspect population figures in any given country under normal times don't tend to vary by even 1% (for the US this is over 3 million) ignoring overall growth/decline. It would be better in both cases (McDonalds and internet) to think in terms of averages over a time interval (say average per/day). (Another issue of course is what is a computer? Is a Wii? A mobile phone? A router? A fridge? And if I have a P2P app in the background while playing a non online game am I using the internet? What about if I'm occasionally messaging a friend online?) Nil Einne (talk) 17:21, 16 July 2008 (UTC)[reply]
I think Nil has it exactly right that the internet as we conceive it has to be looked at as a system in flux. I suppose there's some way of estimating the amount of data stored on all the servers, but it would be a poor estimate for a whole host of reasons. To name only one of the most obvious, a media file that no one has uploaded or downloaded in months might count for just as much as some hot video on YouTube seen by millions a day. I disagree, however, that we have to work at defining a computer; all we need to measure is traffic; I don't think it really matters what device is doing the uploading or downloading. If we stick with the traffic definition, Nil's P2P app would simply contribute to the download or upload quantity. Matt Deres (talk) 18:42, 16 July 2008 (UTC)[reply]
If it is asking for any advice on treatment, diagnosis or signs and symptoms (the latter is my opinion) then it is a request for medical advice. The specifics, such as the effects of Citirizine, are irrelevant :) —CycloneNimrodTalk?06:36, 17 July 2008 (UTC)[reply]
An inter-fabric-of-cosmos-wormhole/grayhole
Today while I was exercising I thought that in a supermassive blackhole, the fabric of cosmos might break, and the matter will just swarm to the other side of the fabric of cosmos, and warp timespace oppositely by warping on the opposite side of the fabric of cosmos. As the warp builds, it might create a black hole on the other side, which is equivalent to a white hole on our side though no mass is on our side of the fabric of cosmos the place of black hole there(a zero mass black hole(zero mass black holes also act like white holes)). But, due to the hole created by the supermassive blackhole mentioned in the first line will make the matter swarm to the other side and again and again and again... But another thought is that only half of the matter will swarm to the other side, but the fabric of cosmos cannot warp due to having equal mass on both sides and either stabilizing the warp or the fabric of cosmos spiting in half, and having created a new universe with the new half. Still, another thought lead me to thinking the hole will create a big bang on the other side with the matter spreading out, like the big bang, and matter continuely falling over the other side and after half of the matter falls to the other side, pressure will slow down the transfer, but the trend remains. After all the matter flows there, it might ignite a new big bang on the opposite side once again. Or perhaps the matter will equalize and.. the possibilities are infinite. Could such phenomena happen? please reply!!! —Preceding unsigned comment added by Superwj5 (talk • contribs) 12:21, 16 July 2008 (UTC)[reply]
Please see black hole and white hole. This is a reference desk, not a "tell me if my most recent theory is valid" desk. You appear to be in need of a discussion forum. There are thousands (if not millions) of them on the Internet. This is not one. -- kainaw™12:35, 16 July 2008 (UTC)[reply]
It sounds like you're thinking of the universe as a rubber sheet being warped by massive objects, which is a good analogy up to a point, but isn't entirely accurate. There isn't really an "other side" to the universe where massive objects would push the universe in the other direction, at least not in a standard interpretation of general relativity (M-theory might have something along those lines, I've never studied it). --Tango (talk) 22:17, 16 July 2008 (UTC)[reply]
I have fallen for the marketing tactics - i've bought myself an energy-drink in anticipation of 'cup finals' night at my local football thing tonight. Putting to one side the question of whether energy-drinks produce any increase amount of energy/stamina does anybody know how long before said game is 'optimum' for drinking said energy drink? E.g. Before I play I use my inhaler about 30 mins before (as directed by my asthma nurse) and that tends to mean I don't need to use it during the game. Should I drink my drink 10 mins before, 30 mins, an hour, 2 hours? Granted I don't believe these have a 'major' impact but given that i've bought the drink already I might as well try drink it at the best time possible.
I ask because i'm thinking whatever is in the drink (sugar and chemicals no doubt) needs time to 'work' or be 'digested' or something. Any help greatly appreciated. 194.221.133.226 (talk) 13:17, 16 July 2008 (UTC)[reply]
They are pretty much sugar-water, with maybe some caffeine tossed in. Since sugar is rapidly digested, I'd drink it right before. There is also the "sugar crash" to consider, which will cause you to rapidly lose energy as soon as the sugar rush is countered by your own insulin production. Starches are usually suggested to be eaten with sugar, since they are digested a bit slower, and then hold blood sugar steady when it would otherwise crash. Protein and then fats are good for even longer terms. StuRat (talk) 14:13, 16 July 2008 (UTC)[reply]
In most energy drinks, it is not caffeine that provides energy. Caffeine simply helps to bypass your body's feeling of fatigue and helps keep you awake. That is of course a benefit to someone who needs to stay up late working. The energy that you need to be more active is provided by, as StuRat said, sugar (ususally glucose or dextrose, I think it's the former in Lucozade). This is digested very early on and doesn't go through the entire small intestine, as you would expect larger proteins and lipids to do. Energy drinks also contain taurine which helps to do a lot of things but in energy drinks it's particularly helpful due to it's effects of countering osmotic shock (good if you're an athlete) and it's role of being a surfactant of the cholic acid conjugate.
Basically, I recommend you'd drink your energy drink about 10-15 minutes before the game. This should mean it's starting to be digested roughly as the game starts and should give you a pretty optimum time with a 'sugar high' before the crash. — CycloneNimrodTalk?15:31, 16 July 2008 (UTC)[reply]
When I suggested drinking it right before the event, I was assuming the athlete would have sufficient energy at the start, and would only need the energy burst later on once they burned off that initial energy. StuRat (talk) 23:07, 20 July 2008 (UTC)[reply]
It also ensures that you're on the loo just when the quarterback makes that fantastic throw right to the runner in the end zone while the cheerleaders flash the other team. Or you keep the empty bottle handy ;-). --Stephan Schulz (talk) 00:19, 17 July 2008 (UTC)[reply]
Ooops...this may be telling about my mindset! I assumed, of course, that the original poster tried to keep awake on the couch while watching the game (in which case the empty bottle can be used as an emergency solution in a private situation), not actually playing in it. If you are actually playing the game, just stick to a fruit juice/water combo. The energy drink is great for after-the-game. Most energy drinks are great at masking the taste of Vodka... --Stephan Schulz (talk) 13:03, 21 July 2008 (UTC)[reply]
The discrete movements of chickens
Why do birds move their heads in discrete amounts rather than in smooth and continuous motions as mammals do? They look almost like they're in stop-motion. I can explain further if you don't know what I mean. --Sean13:22, 16 July 2008 (UTC)[reply]
I believe they have optical processing in the brain that enables them to easily spot moving objects against a still background (we have this ability, too). This works better if the head is held still to prevent apparent background motion. So, they hold their head still for a bit then quickly move it to the new position for another "snapshot", while walking. This might bring up the question "why don't humans do this ?". Our heads and brains are too big, such that repeated, quick, jerky motions like this would make us dizzy and/or cause us brain injury (although we might hold our head still while trying to spot a small object moving in the distance). So, apparently there is at least one advantage to having a bird brain. StuRat (talk) 13:43, 16 July 2008 (UTC)[reply]
You may want to read the saccade article. My guess is that since the eye motion amplitude in birds is somewhat limited (or sometimes very limited, as in barn owl), rapid head rotations are actually saccades. --Dr Dima (talk) 13:52, 16 July 2008 (UTC)[reply]
There are four reasons:
1. Balance
2. To achieve depth perception through their (virtually) monocular vision
3. To read a stable image from their sub-standard eyes
For "why don't humans do it"... We have depth perception without jerking our heads from side to side. If you lost one of your eyes, you may jerk side to side more to get a sense of depth - and likely become rather accustomed to overlaying something you just saw onto something you currently see - just like a chicken. -- kainaw™14:53, 16 July 2008 (UTC)[reply]
Most birds eyes are located on the sides of their heads, permitting them to see over 300 degrees without moving. However, the disadvantage of this positioning is that movement produces motion parallax errors - objects nearby appear to move faster than objects further away. To preserve visual acuity, a bird will lock its head in position whilst moving its body beneath it. It will then move its head to the next 'lock' position, which it again holds. In this way the parallax effects are minimized. Incidentally, the combined action of "head locking" with walking gives certain birds (such as pigeons) the characteristic nodding appearance. See here and here for in depth studies. Rockpocket20:33, 26 October 2007 (UTC)[reply]
So, why don't all birds do this? Gulls (just to use an example I'm familiar with) have eyes placed at the side, yet they walk with a straight neck. --Kurt Shaped Box (talk) 22:56, 16 July 2008 (UTC)[reply]
Good question. According to the second source, "This behaviour occurs in at least 8 of the 27 orders of birds including relatively common species such as pigeons, doves, hens, starlings, pheasants, coots, rails, sand-pipers, phallaropes, parrots, magpies and quail." So why not the others? Well, it might be something to do with the neural architecture of the visual system, or it could be do with ecology, or both. It appears to me that most of those listed above would have predators and it might in in their interest to have an ability to watch out for them with good visual acuity. Bird without natural predators may not have the same requirement. This is purely speculative, though. Rockpocket18:48, 17 July 2008 (UTC)[reply]
i have searched for information on ABSOULUTE POSITION. that is, to be stationary (say, outside the universe) I would like to know (1) If this is possible, and (2) What would be observed' —Preceding unsigned comment added by 86.158.32.65 (talk) 22:13, 16 July 2008 (UTC)[reply]
I'm no astrophysicist but i'm pretty sure we don't know anything about what is outside the universe, certainly not if it's possible to go there or not. —CycloneNimrodTalk?22:18, 16 July 2008 (UTC)[reply]
By definition, the universe incorporates everything that exists. If there are other universes with their own scientific laws, constants, or events (see many-worlds interpretation), its inhabitants would be unable to observe us and we would be unable to observe them.
One exotic method of travelling to universes is via wormholes, which require the existance of black holes with no mass. There are two problems with this: (1) black holes are the result of the collapse of massive stars, and (2) any theoretical black hole with no mass would cease to be a vacuum when matter contacts it. --Bowlhover (talk) 23:59, 16 July 2008 (UTC)[reply]
specifically, the recommendation to use DOVE brand soap, which is 1/4 moisterizer, just seems wrong. here is a list of ingredients mine lists: sodium lauroyl isethionate; stearic acid; sodium palmitate; aqua; lauric acid; sodium isethionate; sodium stearate; cocamidopropyl betaine; sodium palm kernelate; parfum; glycerin; sodium chloride; zinc oxide; citric acid; tetrasodium EDTA; tetrasodium etidronate; alumina; alpha-isomethyl ionone; benzyl alcohol; butylphenyl methylpropional; citronellol; coumarin; hexyl cinnamal; limonene; linalool. cl 77891. I'm not asking for medical or dental advice, but couldn't someone brushing their teeth with that stuff like, get, aluminum poisoning or something? Are any of those ingredients toxic or otherwise harmful? Wouldn't they, at a minimum, wear down the tooth enamel? surely it's no substitute for toothpaste, and even if it's true that "brushing your teeth with a regular unscented bar soap can kill all germs and remove all plaque and tartar that ordinary tooth paste cannot remove" surely there must be something equally negative about it, such as I don't know getting poisoned, or losing your tooth enamel. Otherwise why wouldn't toothpaste just have that stuff to begin with? I am emphatically not asking for medical, dental, or legal advice, just curious what the science behind that might be... —Preceding unsigned comment added by 83.199.57.103 (talk) 22:52, 16 July 2008 (UTC)[reply]
It is very hard for human digestion to absorb aluminium, particularly from something insoluble like alumina. Those that are poisoned by aluminium, usually have it introduced to the blood. You will find that toothpaste can have some of those ingredients, and can make similar claims to removing plaque. The soap probably tastes horrible. Graeme Bartlett (talk) 23:09, 16 July 2008 (UTC)[reply]
The concern about aluminum, in recent years, has not been so much about acute aluminum poisoning as about the fact that aluminum has been found in the plaques in the brains of Alzheimer's patients. As I understand it, this concern has dissipated somewhat with the failure of researchers to find any direct causitive, connection, but the jury still seems to be out: this article asserts
While a direct causal role for aluminum or other transition metals (copper, zinc, iron) in AD has not yet been definitively demonstrated, epidemiological evidence suggests that elevated levels of these metals in the brain may be linked to the development or progression of AD.
are you guys telling me that despite being 25% moisterizer if the ingredients are as above, they shouldn't be harmful to use in place of toothpaste? What about my enamel question?
I'm not telling you anything of the sort. I mostly responded to get the correct spelling of aluminum into the text as many times as possible. Because that's how aluminum is spelled, you know. Aluminum. --Trovatore (talk) 23:42, 16 July 2008 (UTC)[reply]
Aluminium is a silly word; aluminum as derived from alumina was just fine, until someone decided to add the spurious i. Who knows how much platinium someone paid to IUPAC to pick the wrong spelling, but they have no authority. --Trovatore (talk) 23:56, 16 July 2008 (UTC)[reply]
Pah! I won't accept it. It may take another millenum before I can ententan such a thng! -) (a smiley without spurious 'i's). Seriously though, spelling differences are interesting, and Alumin(i)um has an interesting history in that regard. Fribbler (talk) 00:04, 17 July 2008 (UTC)[reply]
Common sense says it should be aluminum, as derived from alumina. Consistency with what? There are other element names that end in um -- platinum, tantalum. --Trovatore (talk) 17:18, 17 July 2008 (UTC)[reply]
But far more with ium, Americium, Barium, Berkelium, Beryllium, Bohrium, Cadmium, Caesium, Calcium, Californium, Cerium, Chromium, ... I'm now getting bored, but you get the picture, about half of all element names end in '-ium' and all recently named ones do, so this suggest convention is in favour of an 'ium' ending, with those without being the spurius early discoveries for which there was no naming convention. Aluminium QED. Philc 0780 11:32, 18 July 2008 (UTC)
No, that's completely wrong. Aluminum is just what you get when you change alumina from first declension feminine (or second neuter plural) to second declension neuter singular. Simple, clean, obvious.
As I say, alumium (derived from alum rather than alumina) would also have been OK, but it didn't win out, whereas aluminum did, in the dialect of English spoken by more than 60% of first-language speakers worldwide, namely North American English. --Trovatore (talk) 15:48, 18 July 2008 (UTC)[reply]
I'm sorry, but, WHAT!?!?!?? you think american english is the first language of 60% of the worlds population? do you live under a rock? are you infact some sort of shrew or snail? English in all its dialects is only the first language of 5% of the population! all I can hope for is that you added spurious 0 to your number! p.s. you mispelled aluminium again. Philc 0780 12:36, 25 July 2008 (UTC)
I checked out the interwiki links of Aluminium, and I didn't find ONE single language, except for English, that calls it Aluminum or similar. Almost all entries using our writing systems have it ending with "-inium". :-) Aeluwas (talk) 13:35, 17 July 2008 (UTC)[reply]
So what? It was discovered hmm--not quite "discovered" maybe; "first named" anyway by an English speaker, and he called it aluminum (well, first he called it alumium, which would also have been OK, but it doesn't seem to be a contender anymore). --Trovatore (talk) 17:18, 17 July 2008 (UTC)[reply]
Well, they're deliberately using a product for a purpose it is not meant for, and has probably not been tested as safe for. They're also foregoing the aspects of toothpaste that are known to be beneficial—the fluoride compounds. And they're justifying it based on ad hoc ideas about the benefits of anti-bacterial soap should affect their mouth (which they know nothing about—there are many types of helpful bacteria in the human body, and rampantly introducing anti-bacterial agents into different parts of it is not a great idea), and rumors about toothpaste (evil glycerin etc.), and then justifying it not with systematic testing, but confirmation bias-rich anecdotes. So yeah, in my book they're doing a few things wrong, a priori. I mean, science ain't perfect, and for that matter neither are regulatory agencies, but I trust them a lot more than some anonymous yokels on the internet and their folk medicine. --98.217.8.46 (talk) 00:10, 17 July 2008 (UTC)[reply]
Toothpaste and soap differ in detergent content--it's the main ingredient in any soap. Detergents can contribute to wear of dentine[4] and soap can reduce the strength of dentine bonding agents[5]. These people may experience a subjective benefit, but I couldn't readily find anything in PubMed that would suggest that this is an idea currently studied or recommended by the dental community, but these two studies indicate potential problems to worry about with this technique (beyond the aforementioned lack of safety testing & no fluoride benefit). — Scientizzle17:51, 17 July 2008 (UTC)[reply]
is there a distance where eye focus and binocular effect disappears?
Is there a distance at which no normal person can tell, without moving their head for parallex effect, whether there is a poster (for example) at that distance or, for example, a mountain hundreds of miles further, because the focus and binocular effect have become imperceivable? Sorry for the awkward phrasing, I think you get what I mean and you're welcome to offer to a better phrasing.—Preceding unsigned comment added by 83.199.57.103 (talk) 22:39, 16 July 2008 (UTC)[reply]
Yes and no. Somewhere around 20-50 feet away, binocular cues start being useless for depth perception, but the brain uses many other techniques as well. You might be interested in the article depth perception and the articles linked from the "monocular cues" and "binocular and oculomotor cues" sections. --Carnildo (talk) 23:22, 16 July 2008 (UTC)[reply]
you said binocular cues are useless, is that true of focus too? —Preceding unsigned comment added by 83.199.57.103 (talk • contribs) 23:39, 16 July 2008
Yes, because compared to the size of a human eye's lens, 20-50 feet is almost an infinite distance. Imagine a point source of light at 7 m with the middle of the lens directly facing it. Since the source's image on the retina must also be a point, the lens refracts all light rays onto the centre of the retina. 5 mm from the lens' centre, light from the source is bent by 0.04 + x degrees; a refraction of 0.04 degrees would cause the light ray to be perpendicular to the retina, while an additional x degrees is needed for the ray to hit the retina's centre. Rays from an infinitely-distant source are refracted by x degrees, where is only 0.04 degrees less than the source at 7 m.
As for the binocular effect, the distance between the eyes is 5 cm. The angular positions of a 20-ft-distant object that the eyes report differ by 0.6 degrees, which is the angular diameter of the Sun--probably large enough to notice. 30 m is the distance at which an object's apparent positions differ by 0.1 degrees, so I would say the binocular effect absolutely cannot be used at greater distances. --Bowlhover (talk) 01:08, 17 July 2008 (UTC)[reply]
This is just anecdotal, but it relates to the question, so I'll tell the story. I wear glasses for myopia. One time years ago I got a new prescription for slightly stronger glasses. I put them on in the optician's office and they seemed fine. I then stepped outside and discovered that most of the world had become flat: nothing was farther than 20 feet away! I was traveling by public transit and next had to cross a 4-lane street to get to my stop, and crossing the street with that illusion in place was downright surreal. The cause, of course, was that with the old prescription my eyes had been unable to quite focus at infinity -- and my brain had learned to use this as a distance cue! Anything that's in sharp focus, it had learned, must be 20 feet away if binocular vision doesn't say it's closer.
Fortunately, the brain adapts well; the effect faded within an hour. --Anonymous, 05:30 UTC, July 17, 2008.
Another anecdote. I've found that looking at photos with a significant depth (it works better with some then with others) with one eye gives them an almost 3D look. Obviously with no binocular vision, the brain starts to look at other clues more and you see depth that isn't there Nil Einne (talk) 11:19, 17 July 2008 (UTC)[reply]
If one has a molecule which has coordinate covalent bonds - that is, both electrons for the bond are provided by one atom - how is hybridization calculated? For the atom providing the electrons, I believe the bond counts as an unshared pair of electrons, but does it affect the hybridization of the receiving atom? If so, how? As an example: I believe sulfuric acid, H2SO4, has two coordinate covalent bonds between the central sulfur and two of the oxygens. How would one calculate the hybridization for the oxygens? FlamingSilmaril (talk) 00:21, 17 July 2008 (UTC)[reply]
I believe once the bond has been formed, it is treated like any other covalent bond. It doesn't matter where the electrons came from; they are shared between the atoms the same as if it is a coordinate covalent bond, a "normal" bond, or from some sort of electrochemistry. As the article says, it's an "artificial" distinction. --Bennybp (talk) 00:54, 17 July 2008 (UTC)[reply]
(Hopefully someone can correct me if I'm wrong; it's been years since I've done this). For the oxygens with a double bond to the sulfur, the hybridization would be sp2 - 2 hybrid orbitals containing the 2 loan lone pairs, and one containing the σ bond to the sulfur. The leftover p orbital is used in the double (π) bond. For the oxygens containing to the H group, the hybridization is sp3 - one containing the bond to the sulfur, one containing the bond to the hydrogen, and two containing lone pairs. --Bennybp (talk) 01:39, 17 July 2008 (UTC)[reply]
Okay, that makes sense. But are the bonds double (in which case sulfur would need an expanded octet) or coordinate covalent? In my high school chem class they told us it would be coordinate covalent, but are they dumbing it down for simplified chem 1 purposes? And if it's coordinate covalent, does that change things? Thanks for your help. FlamingSilmaril (talk) 01:55, 17 July 2008 (UTC)[reply]
Hybridization schemes involving d orbitals are also possible. They are important for elements in the third and succeeding rows of the periodic table. Although the elements of the third row do not possess occupied 3d orbitals in their ground electronic configurations, the 3d orbitals of phosphorus, sulphur and chlorine are low enough in energy that promoted configurations involving the 3d orbitals may be reasonably postulated to account for the binding in compounds of these elements. One consequence of the "availability" of the 3d orbitals is that there are many exceptions to the octet rule in compounds of the third row elements
That may still be debatable. (or no longer believed true). You probably don't have to worry about that anyway - d orbital contribution may only be partial.
The hybridisation on O is difficult - for the OH oxygens you can expect sp3 (as in water), for the =O oxygens you might expect that the double bond be provided by a p orbital - this means that the remainder of the orbitals can form sp2 or (sp and p).
It's worth noting that the S=O bond can be quite polar eg S+-O- ; negative charge on the oxygen tends to favour s or sp orbitals (I think)
(eg compare the stabilities of CH3-, CH2=CH- and CH=CH- anions -also a first row element).
The SO bonds are double, the SOH bonds are single.
The S can be considered to have and expanded octet.
The S=O bonds can be considered to be dative from S to O or as a single bond sharing one electron each from S and O with O supplying a further dative bonding pair to S forming the double bond and expanding the S octet.
1. OH
|
-O-S2+-O-
|
OH
2. OH
|
O=S=O
|
OH
3. O
↑
HO-S-OH
↓
O
1,2 and 3 are all valid structures, 1 shows a polar covalent bond, 2 shows the double bonds , 3 shows the dative bonding form. NOTE only in 3. has sulphur not expanded its octet.
1 is unlikely because of the +2 charge, 2 is more likely because the S=O bonds are shown to be quite strong, for that reason the singly bonded form 3 is unlikely.
Ah, see the picture to the right. You are correct - sulfur contains an expanded octet - two double bonds, two single bonds, for a grand total of 12 valence electrons. Perhaps your teacher misspoke or was incorrect in calling the bonds "coordinate covalent" (or dative, the term I had learned). A double bond is of course a type of bond. A coordinate covalent/dative bond is more of a description of how that bond got there. Once the bond is formed, it's more or less irrelevant how those electrons came to be shared. Sulfuric acid structure--Bennybp (talk) 02:56, 17 July 2008 (UTC)[reply]
Quick note about the hybridized d oribitals mentioned above - you are also correct. In some there can be hybridized sp3d, sp3d2, etc, in some compounds. In this case, who knows. Maybe I'll rummage through my inorganic book tonight. I'm just thankful he/she didn't ask what the hybridization was on sulfur. Yet. :) --66.66.215.73 (talk) 03:28, 17 July 2008 (UTC)[reply]
(unindent) Thanks to everybody who has contributed to the discussion. I do have one question remaining: the article on thiosulfuric acid has the atoms arranged in a cross structure around a sulfur. An AP Chem book that my teacher used said that it is arranged in a straight line: H-O-S-O-S-O-H. It said this was more stable, because it was slightly more symmetrical. A quick glance however, does not show this structure anywhere on the internet. Can anybody shed some light on this? FlamingSilmaril (talk) 22:27, 17 July 2008 (UTC)[reply]
Your book may be wrong, or someone misinterpreted (what book is it?). The structure you gave (H-O-S-O-S-O-H) is 1.) Not linear. 2.) Not symmetric (well, maybe one rotational axis through the center oxygen). 3.) Not thiosulfuric acid. And 4.) Doesn't appear to exist. (The structure was evaluated with ChemSketch,and named "dihydroxydithioxane", which gets zero hits on google and ChemFinder. --Bennybp (talk) 23:28, 17 July 2008 (UTC)[reply]
I'm sure most of us have heard the stories of human vs. kangaroo boxing matches (which are probably illegal in many parts of the world now) at carnival sideshows in the 19th century. What I'd like to know, is whether a trained boxing kangaroo could beat a skilled human boxer. There are some videos of man/kanagroo fights on YouTube - but they all seem to involve the human fighting half-heartedly or refusing to fight back at all for the purposes of comedy.
So, if a (good) boxer really went all out and genuinely tried to KO the 'roo - and the 'roo was likewise trying to inflict serious damage (both wearing gloves, of couse - this is a civilised sport!), which would be the more likely winner? --Kurt Shaped Box (talk) 01:30, 17 July 2008 (UTC)[reply]
I have witnessed a boxing match between kangaroos. They don't follow rules, and also use their strong hind legs. A kangaroo could out jump a boxer. Scratching with claws is part of their methods too. Graeme Bartlett (talk) 04:59, 17 July 2008 (UTC)[reply]
As regards gloves and civilzed-ness: KSB, do you have the idea that when you put on gloves you do it to protect your opponent? No. You do it to protect your own hands, so you can hit your opponent harder. --Trovatore (talk) 05:09, 17 July 2008 (UTC)[reply]
That's talking about gloves+padding, versus gloves without padding. Gloves without padding still protect your hands. Put a bare-knuckle guy in the ring against a guy with gloves, I'll bet on the guy with gloves. The reason bare-knuckle fights could go 57 rounds or whatever is they just couldn't hit each other that hard. --Trovatore (talk) 17:06, 17 July 2008 (UTC)[reply]
My dad worked in a hospital emergency room for a while, and according to him, bare-knuckle bar fights end in either of two ways: (1) the guy throwing the first punch is strong, and breaks his own hand and his opponent's jaw, or (2) the guy isn't so strong, and only breaks his own hand. In either case, punching someone in the jaw with your bare hands is not a good idea. --Carnildo (talk) 20:48, 17 July 2008 (UTC)[reply]
AFAIK, if you break your hand when punching someone, it's usually down to bad technique. For some reason, when untrained people punch, they tend to connect with the fourth and fifth knuckles. Not that I'm a scrapper - but I think the trick is to strike with the second and third, with a straight wrist behind. --Kurt Shaped Box (talk) 22:57, 17 July 2008 (UTC)[reply]
Odd. The claim is that half the padding had been removed from the gloves and that that allowed Resto (who is referred to as "soft-hitting") to beat the good guy half to death (or, if we ignore the DUI as the article does, all the way). But boxing gloves are much more padded than those used in MMA - even half the padding would leave them bulkier than a UFC fighter's gloves. Lewis and Resto are rightly demonized, but the key element here was the incompetent referee who apparently didn't feel the need to check the fighter's equipment or stop a bout that had obviously become a slaughter. Matt Deres (talk) 10:53, 17 July 2008 (UTC)[reply]
I don't really know much about the UFC - but does a typical bout of theirs involve 10x3min rounds of mostly punching someone in and around the face? I thought that it was more of a grappling-based sport? The Collins-Resto fight is on YouTube in its entirity, btw - it doesn't actually look massively uneven until the last three rounds or so. Even then, it was only in the final round that Collins was struggling to stay on his feet. The damage inflicted was cumulative. --Kurt Shaped Box (talk) 15:04, 17 July 2008 (UTC)[reply]
A typical bout is 3x5 minutes, but a title match is 5x5 minutes. While they don't experience the sheer number of punches to the face that a boxer would get, they also get to enjoy kicks, knees, and forearms to the head. I stopped watching boxing as I got into watching MMA style events; while that was mostly driven by the (IMO) more exciting style of contest, I also preferred the sportsmanship and style of refereeing. Maybe it's gotten better over the last decade, but when I was watching boxing it seemed that the refs were doing everything in their power to allow the superior fighter the chance to KO his opponent, rather than simply stopping the fight (as a TKO) when it became obvious that the match had really already been decided. Not having been pummelled myself (!), I tend to agree with Bas Rutten that a quick finish to a fight is much better for the health of the fighters than a prolonged battle with standing counts and more frequent breaks between rounds. In MMA, the referee (or designated other) also inspects the equipment immediately prior to the bout to make sure everything is up to spec. Matt Deres (talk) 16:37, 17 July 2008 (UTC)[reply]
Concentration of biotin in egg yolk.
On a number of websites I've read that despite egg whites containing a substance that removes biotin from the body, egg yolks contain so much biotin to make these effects unimportant. I have however been unable to come up with a source for this -- Wikipedia's own article on biotin mentions that egg yolk contains biotin, but does not reference a source that I can see.
Another Wikipedia article (http://en.wikipedia.org/wiki/Tamago_kake_gohan) states that "Eggs contain many nutrients and protein which are denatured when cooked; therefore it is thought that eating them raw maximises the beneficial effects of these nutrients. The egg yolk contains more than enough levels of biotin to compensate for the high levels of avidin in raw egg white, which binds to the B-vitamin biotin, preventing their absorption and potentially causing a deficiency if the yolk is not consumed with the white." The source it sites for this is a pdf of a letter about, amongst other things, whether wolves should be classed as dogs, and it doesn't exactly inspire confidence in the claim. I'm just looking for a source that gives some exact figures...
Additionally, there is often a claim made that salmonella contamination in eggs only comes about if the chicken is ill, and thus if you buy organic or free range eggs then it is less likely to be infected with salmonella. I have been unable to find a source for this claim either.
After searching on Google, I found [6], [7], and [8], all of which claim there is insufficient avidin in an egg to bind all of the egg's biotin. However, according to this paper, "The yolk of an egg is rich in biotin, but the white usually contains more than enough avidin to inactivate the yolk biotin."
On the matter of salmonella, the U.K. Food Standards Agency found no statistically significant correlation between production type and incidence (see [9]).
Just a historical note: the discovery of avidin/biotin binding and its effects upon the body was by observing a strange ailment affecting a number of athletes who had only one thing in common: they all had been consuming a number of raw eggs (not just the whites, but whole eggs) for a period of at least several weeks. The ailment turned out to be biotin deficiency caused by the sequestration of the vitamin by the avidin in the raw egg. – ClockworkSoul18:07, 17 July 2008 (UTC)[reply]
Litmus paper contains a variety of indicator dyes. The reaction that takes place is a simple acid-base proton (or hydroxide)exchange of the form HIn -> H+ + In-. Indicators are special in that when they lose or gain protons, the absorptive properties of the molecule as a whole are changed. The Phenolphthalein article has some good structures that might help you understand how the conjugated system in the molecule is effected by pH change. --Shaggorama (talk) 04:31, 17 July 2008 (UTC)[reply]
Fixed your confusing typo. --Anon, 05:34 UTC, July 17.
Dream length
What is the average length of a dream? Doing a quick google search gives me results ranging from dreams lasting a split second to experiencing dreams in real time. --Metalcore424 (talk) 09:17, 17 July 2008 (UTC)[reply]
I don't think today it can reliably be measured. In this case measurement of the system drastically affects what we are trying to measure, which would lead to unscientific data and results. Mac Davis (talk) 00:04, 18 July 2008 (UTC)[reply]
Not only that, but you have the problem of what defines a dream; I have had one right after the other, and I would think there was no space in between them, though I'll admit there could have been and I'd never know it. If they can come one after the other, why does your brain change...well..plots? Hmmm, maybe reading the article will help me some witht hat one.209.244.30.221 (talk) 17:35, 20 July 2008 (UTC)[reply]
Given the continental drift over the past 65 million years, it seems as if the impact crater and the caldera were on almost precisely opposite sides of the globe at the time of the event. Are there any theories that somehow make a connection between these two? Frunobulax (talk) 14:45, 17 July 2008 (UTC)[reply]
As dating accuracy gets better, the results repeatedly show that the Deccan Traps predate the Chicxulub crater. It is possible that they happened at the same time - but at this time not widely accepted. If it is proven that they happened at the same time, that will not prove causation. -- kainaw™14:59, 17 July 2008 (UTC)[reply]
They say that the Deccan Traps is the result of a deep mantle plume. These types of plumes happen from time to time all over the world without any special provocation, although the Deccan Traps is a particularly splendid example. Some people have suggested that the impact which caused the nearby Shiva crater may have disturbed the mantle and triggered the plume which formed the Deccan Traps. But really, who knows? PlasticupT/C19:02, 17 July 2008 (UTC)[reply]
You know that funny feeling in your forehead when you place something close to your forehead or inbetween your eyes (especially if it's pointed like a pencil)? How does that work? It seems to activate even if I close my eyes. I never really understood how it works or why. ScienceApe (talk) 15:17, 17 July 2008 (UTC)[reply]
I don't get a funny feeling. Can you describe it in any more detail? I wouldn't recommend putting pointy things too near your eyes though.--Shantavira|feed me15:54, 17 July 2008 (UTC)[reply]
It seems to work more when someone else does it. Have someone point their finger inbetween your eyes or near your forehead. Don't let them touch your head though, but you'll get a funny feeling in your forehead. ScienceApe (talk) 16:00, 17 July 2008 (UTC)[reply]
I definitely know the feeling you mean, but I can't think of what it could be called to search for it here or on google. Fribbler (talk) 16:07, 17 July 2008 (UTC)[reply]
It feels like blood rushing to the area, so maybe it is my body anticipating an impact from the object directly in front of me. PlasticupT/C18:51, 17 July 2008 (UTC)[reply]
I think it is probably due to your eyes trying to see it in your peripheral vision. I don't feel anything nearly at all when I do it with my eyes closed. --98.217.8.46 (talk) 03:52, 18 July 2008 (UTC)[reply]
Since the eyes and brain are very sensitive areas, I suspect the sensation is to warn of a potentially-dangerous object. It still exists when the eyes are closed because when you deliberately induce the feeling with an object, you're well aware of the object's position. When an item unexpectedly gets close to the forehead, I think wind and changes in the amount of light received by the eyes can reveal its location. --Bowlhover (talk) 08:47, 18 July 2008 (UTC)[reply]
I don't know it is the same but my forehead seems much more sensitive to heat or cold than the rest of my face. I can easily tell if there is a hand a couple of inches in front of my forehead with my eyes closed because of the heat. You might feel it as blood rushing to the area. Dmcq (talk) 20:08, 18 July 2008 (UTC)[reply]
ESPAurapersonal bubble its basically latent esp in non-phsycis, and goes to prove that most people are phsycic to a certain degree. It used to happen to me in a hardware store I used to visit, one isle had many habgers for bags of screws and such like and was basically 6 inch rods of metal in an isle 10meters long, 4 feet high and one of there every 10 square cm or so really wierd feeling walking down that isle, i had to avoid it in the end.
Why would a dark brown haired man find about 4 red beard hairs?
I am 27 years old and am a typical Peruvian in terms of aperance. I have dark brown eyes and hair, both my parent as well and all of my grandparents (all Peruvian). Recently I have decided to let my beard grow a little and I ran into a total of 4 red hairs. I have had white hairs on my head, but not on my beard. Is it normal to have a few hairs of a different color? I am a healthy man maybe a little rounder than what I would like. I stand at 5'9 and weigh 176lb, so I don't think malnutrition would be a cause. Why would I have 4 hairs that are of a different color that are not white? —Preceding unsigned comment added by 167.211.65.80 (talk) 15:23, 17 July 2008 (UTC)[reply]
This is a reference desk. It is not a place to list symptoms and ask for a diagnosis. Anyone who answers this question with a proposed diagnosis will be doing you a disservice. Please see a medical expert for a proper diagnosis. -- kainaw™17:19, 17 July 2008 (UTC)[reply]
The OP doesn't seem to be looking for a diagnosis for a medical condition, just a simple explanation about why he might have variation in his hair color. – ClockworkSoul18:00, 17 July 2008 (UTC)[reply]
I agree, calling a question about why hairs come in different colors a request for a medical diagnosis is absolutely absurd. Let's be reasonable here. StuRat (talk) 22:33, 20 July 2008 (UTC)[reply]
Variation in body hair colour in males is not untypical. The genetic basis of red hair is pretty well understood and there is a reported heterozygote effect (having one copy of a specific gene variant) resulting in red beard hair colour in males who do not have red hair on their head. Why one has just occasional red hairs isn't really known, but is probably due to localized perturbation of the melanocytes in those hair follicle, resulting in the production of phaeomelanin rather than eumelanin. Rockpocket19:11, 17 July 2008 (UTC)[reply]
I have dark blonde hair, but a few red hairs in my beard. It was less alarming in my case because my father and brother have red hair, but I don't think it is uncommon, especially when you are young. PlasticupT/C19:05, 17 July 2008 (UTC)[reply]
I know a girl who is complete red-headed/blonde hair colour type except for one black hair on her arm. It doesn't seem that unusual, really. —CycloneNimrodTalk?19:17, 17 July 2008 (UTC)[reply]
I've noticed that some of my eyebrow hairs are a different color and texture. Interestingly, those are the hairs that don't know when to stop growing and must be clipped back. It's like there are two completely different types of hair there. It sounds like you might have this happening with your beard. StuRat (talk) 22:33, 20 July 2008 (UTC)[reply]
Zebra foals
Is the number of foals that a zebra can give birth to in one single go always 1, or have there been cases of multiple births in zebras? Thanks. Leptictidium (mt) 16:21, 17 July 2008 (UTC)[reply]
Upon what criteria do the publishing companies of journals decided to make a particular article free-access? How does it benefit them. Just a curiosity. Thanks in advance. —KetanPanchaltaLK16:39, 17 July 2008 (UTC)[reply]
They might do this as a loss-leader, i.e. a way of getting notice taken of their journal. Many have a policy of making all articles free-access after six months, a year or two years. By that time the number of paid-for hits has probably decreased to nearly nothing anyway. They'll discuss the policy with the journal editor or editorial board. Different journals are aimed at different markets. Itsmejudith (talk) 18:26, 17 July 2008 (UTC)[reply]
Sometimes, when you publish in an academic journal, you can choose whether to make an article freely available or only available to pay for that journal's subscribers. To make it freely available, the author/institution typically has to pay thousands of dollars. Thus, it is not particularly common. Gjmulhol (talk) 19:58, 17 July 2008 (UTC)[reply]
What is the fucntional role of the foam head on a glass of beer? I've heard different explanations and found the beer and beer head articles lacking: the latter explained the physics behind why beer has a head, but not the gastronomy. Why is it important for some beers to have a certain kind of head/pour and not others? Variations I've heard usually mention some or all of the following: head...
...prevents the aroma from escaping prematurely
...retains carbonation
...guards against "oxidation" (though no one has ever told me of what component of the beer)
...keeps the alcohol from evaporating (unlikely)
...helps keep the beer cold (really unlikely)
I imagine some or all of these are probably true, but I can't find a decent source to back it up. In any event, the article could use a little expansion from a knowledgeable party. --Shaggorama (talk) 17:11, 17 July 2008 (UTC)[reply]
Most of these explanations range from unlikely to slightly silly. Beer head doesn't really affect carbonation or aroma, but is diagnostic of it (I'll explain below), and has little to do with decreasing beer oxidation (which is not a factor over the amount of time it takes to drink a beer). The simplest reason for the head on a beer is because people like it: it's aesthetically pleasing and adds a lovely texture to the entire beer-drinking experience. The size and color of a beer head is influenced by a number of factors, including the amount of protein in the beer (more protein equals more foam, and too much deviation from the standard for the style can indicate problems in the brewing process), the degree of carbonation (again, deviation from the standard can suggest bad things), and the temperature of the beer at the time of the pour (temperature greatly influences taste and aroma; also colder beers develop less of a head, while warmer ones may easily overtop). The perfect head on a beer is therefore a good indicator that all of these vital attributes are in a good balance. Hope this helps. – ClockworkSoul17:57, 17 July 2008 (UTC)[reply]
people like it or not. True, on mainland Europe, for example, most beers will be served with a nice head as it indicates that the beer is sparkling and fresh (hence the reason why some longlasting industrial beers have to add chemicals to produce the head) as opposed to flat or stale. But beware of your average UK pub dweller who is susceptible to throwing his pint at the barman if there is any head at all. I think the general feeling, somehow, is that it robs you of beer. From my experience though even in the UK some head is appreciated on a lager as long as its not more than a 1/4 inch thick or so. Also, each beer has its own optimal head (wether it's aesthetical or else I don't know) and you'll find some beers like the Belgian Duvel for which the head is higher than the liquid beer (although the glass it should be served in is thinner at the top so the foam might be less by volume). I think traditionally beers didn't really keeps for much more than a week and were at their best a few days after brewing, so the head is a good indication of how fresh the beer is. 190.190.224.115 (talk) 21:26, 17 July 2008 (UTC)[reply]
"I think the general feeling, somehow, is that it robs you of beer." Yes. If you've got a pint glass and two inches of head on the beer, you do not have a pint of beer. It's a way for the unscrupulous to short-change people. But some adverts are trying to convince the British to think in a European fashion about it and go for a beer with a tall head. Oh the lobsters! 79.66.90.252 (talk) 22:27, 17 July 2008 (UTC)[reply]
The foam on beer has been compared with the volt-amps-reactive (VARS) which come with electrical power (WATTS). Wouldn't be the same without'em. Edison (talk) 04:45, 18 July 2008 (UTC)[reply]
What is the coal-fired power plant with the highest capacity?
I was interested in finding out which coal-fired power plant has the highest capacity, and it seems to come down to two: Bełchatów Power Station and Kendal Power Station. According to the Kendal Power Station page, it is the "largest", which I assume to mean it has the highest capacity. But it has a capacity which is listed as being lower than the Bełchatów station is listed at. I can't find a good source for the capacity of either one of these, and Kendal uses the company's Web site as its source, which is hardly an unbiased source.
I guess I would like to know if there is a good source for this information, and what is a good metric for comparing the size of coal-fired power stations. -- timc talk 17:20, 17 July 2008 (UTC)[reply]
As coal-fired power plants are generally designed to produce electricity, maximum electricity production is probably a good metric. And you can probably trust the company's website for that sort of data. PlasticupT/C18:45, 17 July 2008 (UTC)[reply]
I suggest that the answer lies in the definition of "plant" versus "unit" as to where the largest coal burner is to be found. Edison (talk) 04:41, 18 July 2008 (UTC)[reply]
I can't find a site for Bełchatów, so determining its capacity is difficult. Wikipedia says it is 4400 MW, and Google suggests that this is correct[10][11]. If so, that is higher than the capacity that is listed for Kendal (4116 MW), even though Eskom says that Kendal is the largest. Perhaps the issue is that Eskom is using the superlative "largest", which doesn't necessarily mean that it has the highest generating capacity. But if that is the case, what metric are they using? -- timc talk 15:06, 18 July 2008 (UTC)[reply]
I too found a few spots using Google that confirm Belchatow is rated at 4400 MW. Another metric could possibly be total output in MWh, so if Belchatow has more downtime or more units out of service, it could rank lower. Another possibility is that someone at Eskom just decided to put it on their website. I can't find any reliable source that actually shows a comparison, just news articles that could be repeating the company's own claim. I would say perhaps the articles should be changed to show that Kendal claims to be the largest, although Belchatow has a higher rated output. Franamax (talk) 21:54, 18 July 2008 (UTC)[reply]
Hi all. I'm looking for information about a device that has been circulated around the web as a "levitation" or "antigtrav" device. The General layout is a (usually triangular) light wood frame with some (copper?) wires and a bit of electronics. As far as I could tell, theses things actually do hover, by "somehow" using electromagnetic fields to accelerate air downward. What are those things called, and how exactly do they work (or was it a hoax after all?) I wasn't able to find any information on Wikipedia, it would be grat if this stuff could be mentioned at Antigrav#Conventional_effects_that_mimic_anti-gravity_effects and perhaps corss-linked at EHD_thruster#See_also (even if this is a hoax i'd hope to find information about it on wikipedia).
Sure... but one of the things often claimed to use antigravity. And since that was more or less the only thing i could remember about it, having it under "Conventional effects that mimic anti-gravity effects" seems helpfull and correct. -- Duesentrieb-formerly-Gearloose(?!)13:39, 19 July 2008 (UTC)[reply]
Webless spider
What kind of 1 inch spider would build a short tube type burrow without a trap door under a countertop appliance and then wait at the entrance and chase passing ants no bigger than the tips of its legs? Is there a known spider that would chase such ants and if so how would it eat them if it caught them? -- adaptron (talk) 20:54, 17 July 2008 (UTC)[reply]
I hit "edit" all ready to post a smart-ass answer like "With its jaws, fool" and then realized - I don't actually know how spiders consume their prey, and damned if I can find it anywhere on the wiki. Anyone know? --Random832 (contribs) 15:36, 18 July 2008 (UTC)[reply]
I was going to point out that it could be any funnel spider and most likely the brown recluse. As for chasing prey - that is not normal for any spider I've seen - and I've seen a lot of documentaries on weird spiders. The most common spider will catch prey in a web. Then, there are the ones that wait in a hole (or similar) and surprise prey as it passes by the opening. Finally, there are spiders that drop down on prey from above. Chasing isn't really anything I've seen. As for eating them - spiders inject digestive fluids into the prey and then drink the digested insides back out. -- kainaw™15:52, 18 July 2008 (UTC)[reply]
Brown recluses catch prey by chasing and pouncing on them, rather than by catching them in a web. They are very speedy litle sprinters, and as a result are hard to kill. Edison (talk) 19:19, 18 July 2008 (UTC)[reply]
Firstly you must think of the research ethics. Are you sure it is ethical to treat one of each pair and not the other? Technically, you can randomise by generating random numbers in a computer package such as SPSS or even Microsoft Excel. But should you be doing this kind of research on your own without access to the advice of more experienced researchers? Itsmejudith (talk) 22:00, 17 July 2008 (UTC)[reply]
He said it's a study comparing two treatments, not a study comparing treatment to non-treatment. That's the standard way of doing such studies. I agree, however, that such studies should have the support of a qualified statistician from the start if they are meant to taken seriously - as Ronald Fisher apparently said, "To call the statistician after the experiment is done may be no more than asking him to perform a postmortem examination: He may be able to tell you what the experiment died of." --Tango (talk) 00:21, 18 July 2008 (UTC)[reply]
Yes, I should have read the post more carefully. Even so, ethics is also something that needs to be fully considered at the design stage. Itsmejudith (talk) 07:20, 18 July 2008 (UTC)[reply]
July 18
Over-the-counter diet pills/supplements
Do any of these things actually work? Just browsing my usual online pharmacy site whilst making my monthly nicotine gum order and I stumbled across several claims about 'fat burning', 'fat binding' and 'speeding up metabolism' by various products (some 'herbal', some 'scientific') that sound somewhat improbable... --Kurt Shaped Box (talk) 00:04, 18 July 2008 (UTC)[reply]
In general, they're of variable safety but minimally effective. Many contain stimulants of some sort (caffeine, ephedra, etc.); stimulants have a long history of use in weight loss products (and plenty of side effects that have limited their legal availability--ephedra & fen phen, for example). "Herbal" stuff is almost assuredly worthless: at best it's an unknown dose of caffeine, at worst the unregulated product is laced with more powerful stimulants and compounds that can cause serious drug interaction issues/side effects. — Scientizzle00:22, 18 July 2008 (UTC)[reply]
(edit conflict) We can't give medical advice. You should probably talk to your doctor if you are looking for a way to lose weight. Personally, I would be doubtful of such claims - the only kind of diet pill I can see working is an appetite suppressant. --Tango (talk) 00:24, 18 July 2008 (UTC)[reply]
No, I'm not looking to lose weight. I saw this stuff on the web and wondered how they manage to get away with making the sort of claims they are making about their products. It's quite common in UK pharmacies (real, brick and mortar ones too) to see products that I would personally file away in the quackery/placebo effect bin alongside the healing magnets and activated water. --Kurt Shaped Box (talk) 00:37, 18 July 2008 (UTC)[reply]
I think questions of efficacy can be handled without delving into handing out medical advice, but (of course) a physician would be an appropriate source of information regarding these products. Stimulants, by the way, are often appetite suppressants, having the duel effect of upping energy consumption while decreasing intake (and many unwanted effects, as well). I'd also note that, in the US, there is currently only one FDA approved, over-the-counter weight loss product: Orlistat. — Scientizzle00:41, 18 July 2008 (UTC)[reply]
Interesting, thanks. Some of the pills sold on the site were described as being able to bind to fats in the GI tract, creating large, inabsorbable (is that a word?) molecules which will merely 'pass through'. Does that sound like 'bunk' to you? --Kurt Shaped Box (talk) 00:47, 18 July 2008 (UTC)[reply]
Orlistat does work to prevent fat absorption, so it's possible that in the UK there are similar things on the market that actually do that. However, its method of action is to inhibit an enzyme that makes fats readily abosorbable, not work as some sort of fat aggregator--that sounds psudoscience-esque (but without more information, I can't be sure). — Scientizzle00:54, 18 July 2008 (UTC)[reply]
That page talks about them being on sale in the UK (in the last line), so I guess so... There's one born every minute. --Tango (talk) 01:06, 18 July 2008 (UTC)[reply]
(edit conflict) I've never seen them personally. I noticed the other day that my local pharmacy sells magnetic wristbands for arthritis relief though (FFS!). I've seen ear candles for sale in more than one place too. I'm currently reading through http://www.dietfraud.com/ - a lot of the stuff I've seen advertised does indeed sound like classic 'bunk', according to their writings... --Kurt Shaped Box (talk) 01:07, 18 July 2008 (UTC)[reply]
Heh, I was actually browsing through that site after I finished posting here last night/early this morning. It's amazing what some people will believe, isn't it? --Kurt Shaped Box (talk) 12:58, 18 July 2008 (UTC)[reply]
As someone pointed out somewhere (I forget exactly where), a lot of these things talk about 'unleashing the bodies natural healing abilities'. Magnetic wristbands often do, among others. Anyway, the point is... how would you describe the placebo effect? 79.66.90.252 (talk) 23:08, 18 July 2008 (UTC)[reply]
I'd say many of those might work in the short term, say by having you burn more energy as a result of taking a stimulant or causing you to eat less fat since now you crap your pants if you eat fat (because you're taking a fat binder that causes "anal leakage"). However, as soon as your body adapts and finds other calorie sources to make up for those lost, you likely will gain all the weight back and more. StuRat (talk) 21:25, 20 July 2008 (UTC)[reply]
Carbon dioxide benefit
What articles describe experiments using additional carbon dioxide to help grow more lush plants and what is the maximum percent concentration of CO2 that can be used? -- adaptron (talk) 02:25, 18 July 2008 (UTC)[reply]
Also see Free-Air Concentration Enrichment, though those experiments are designed to test the general physiological and ecological effects of higher CO2 environments, not to look at deliberately using CO2 to increase agricultural productivity, which it sounds like you might be talking about. I'd also point you to Phytotron but it's just a single sentence right now. --Allen (talk) 16:31, 18 July 2008 (UTC)[reply]
first human lunar mission
why does this NASA pdf expect the first human lunar mission a decade from now?
Since the file in question shows the anticipated allocation of NASA's budget, "first human lunar mission" implies more than one future manned mission to the Moon is expected. --Bowlhover (talk) 08:13, 18 July 2008 (UTC)[reply]
I think it's pretty obvious that they mean "first" only in the context of their new push to return to exploration as a primary goal. APL (talk) 14:14, 18 July 2008 (UTC)[reply]
Carbon dioxide risk
The article on Carbon dioxide states that for indoor levels of CO2, "Concentrations higher than 1,000 ppm will cause discomfort in more than 20% of occupants, and the discomfort will increase with increasing CO2 concentration." ... "At 2,000 ppm the majority of occupants will feel a significant degree of discomfort, and many will develop nausea and headaches. The CO2 concentration between 300 and 2,500 ppm is used as an indicator of indoor air quality."
Can anyone confirm that since the article shows CO2 levels were 315 in 1960 and are 387 now there is a .004 exponential rate increase and that in 115 years levels will reach 600 ppm if this rate is maintained and there is no catastrophic change due to some unknown phenomenon? -- adaptron (talk) 06:22, 18 July 2008 (UTC)[reply]
No, it's not currect to state that "since the article shows CO2 levels were 315 in 1960 and are 387 now there is a .004 exponential rate increase". In order to conclude from the measured data that the CO2 level was increasing exponentially and that it therefore would probably continue to increase exponentially, you would need many data points, not just two. Or to reach that conclusion on theoretical grounds, you would need a sound theory to support the hypothesis. --Anonymous, 21:20 UTC, July 18, 2008.
Our article on global warming shows projected levels between 541ppm and 971ppm by 2100, based on a large number of variables and potential actions. As the anon poster says above, you can draw any curve you want between 2 points, however your projection doesn't look all that far off. Franamax (talk) 21:30, 18 July 2008 (UTC)[reply]
It's always incorrect to assume unbounded exponential growth. I'm sure we've got an article on that logical fallacy somewhere. --Carnildo (talk) 21:32, 18 July 2008 (UTC)[reply]
If the blood supply is so important, why do institutions like the Red Cross base it on donations? Wouldn't it be smarter to pay people to donate? And if the shelf life is so limited, why don't they keep a DB of donors and ask them to donate in emergencies? Mr.K.(talk)10:10, 18 July 2008 (UTC)[reply]
I believe Freakonomics discusses this sort of thing. Once you add a monetary incentive, you remove the incentive of the "feel-good factor" of doing a good deed, and you add an incentive to cheat the system somehow. Plus, you have to spend money on paying donors and running the payments system. 81.174.226.229 (talk) 10:55, 18 July 2008 (UTC)[reply]
Our article blood donation explains that it is World Health Organization policy for all countries to move to a volunteer-only system. I believe the thinking is that paid donation creates an incentive for poorer people to give blood, and on average they are less healthy people, hence the greater potential for disease to be spread. My guess is that in most developed countries donors' contact details are kept on a database (unless they take a privacy opt-out). That's certainly the case in the UK. Itsmejudith (talk) 11:00, 18 July 2008 (UTC)[reply]
As for a database of donors, I receive a text message every so often from the Irish Blood Transfusion Board telling me that the blood stocks for my blood group are low, and to go and donate. It may be the same in your country (?). Fribbler (talk) 11:02, 18 July 2008 (UTC)[reply]
I don't donate personally but I've seen people receive cards before when there's a drive near where they live. My guess is O- donors may receive special requests when there's an emergency Nil Einne (talk) 07:44, 19 July 2008 (UTC)[reply]
Normally, in the US, the Red Cross or Lifeline Blood Services or whoever has free orange juice and cookies. Occasionally, they'll give away free t-shirts and other small prizes. I think the last time that the Red Cross came to my workplace to get blood donations, they offered free tickets to the local minor league baseball team's games. Dismas|(talk)14:37, 18 July 2008 (UTC)[reply]
From what I know in the US from my experiences is that they usually give SODA and cookies, even though you're not recommended to drink it after giving blood. And there are often organizations (radio, police, frats, schools) that organize blood drives, and that's usually when you see the tickets and t-shirts. --Wirbelwindヴィルヴェルヴィント (talk) 18:12, 18 July 2008 (UTC)[reply]
The drinks and snacks aren't to thank you for giving blood, they're to stop you fainting on the way home! It's important to replace the fluids, etc. you've just lost. You sometimes get vouchers for ice cream in the UK - particularly in student towns, I think. Ben and Jerry's is a common way of bribing students to do things! --Tango (talk) 21:20, 18 July 2008 (UTC)[reply]
I would guess most of these gifts to donors are in turn donated by whoeever they're coming from so it depends somewhat on who's willing to donate gifts for drive organisers to give to donors. Nil Einne (talk) 07:44, 19 July 2008 (UTC)[reply]
How is body mass index really defined?
The article can't seem to make up its mind. Let Failed to parse (SVG (MathML can be enabled via browser plugin): Invalid response ("Math extension cannot connect to Restbase.") from server "http://localhost:6011/en.wikipedia.org/v1/":): {\displaystyle m}
be a person's mass and let Failed to parse (SVG (MathML can be enabled via browser plugin): Invalid response ("Math extension cannot connect to Restbase.") from server "http://localhost:6011/en.wikipedia.org/v1/":): {\displaystyle h}
be their height. Is BMI defined as the dimensionless number
Failed to parse (SVG (MathML can be enabled via browser plugin): Invalid response ("Math extension cannot connect to Restbase.") from server "http://localhost:6011/en.wikipedia.org/v1/":): {\displaystyle \frac{m/(1\,\mathrm{kg})}{(h/(1\,\mathrm{m}))^2}}
or as
Failed to parse (SVG (MathML can be enabled via browser plugin): Invalid response ("Math extension cannot connect to Restbase.") from server "http://localhost:6011/en.wikipedia.org/v1/":): {\displaystyle \frac{m}{h^2}}
,
having dimension Failed to parse (SVG (MathML can be enabled via browser plugin): Invalid response ("Math extension cannot connect to Restbase.") from server "http://localhost:6011/en.wikipedia.org/v1/":): {\displaystyle \mathrm{mass}/\mathrm{length}^2}
? You might say the distinction is unimportant, but I like to be precise in how I think about things. —Bromskloss (talk) 10:11, 18 July 2008 (UTC)[reply]
:The first example is identical to the second, only that the first have the units defined. These units do not cancel Failed to parse (SVG (MathML can be enabled via browser plugin): Invalid response ("Math extension cannot connect to Restbase.") from server "http://localhost:6011/en.wikipedia.org/v1/":): {\displaystyle \frac{kg}{m^2}}
is the same as Failed to parse (SVG (MathML can be enabled via browser plugin): Invalid response ("Math extension cannot connect to Restbase.") from server "http://localhost:6011/en.wikipedia.org/v1/":): {\displaystyle \frac{mass}{length^2}}
. Jdrewitt (talk) 10:21, 18 July 2008 (UTC)[reply]
The first example is dimensionless; he is explicitly dividing out the units. If my mass is 70 kg, the numerator of the first expression is (70 kg)/(1 kg) = 70, a dimensionless number. The denominator works similarly. The result of the division is thus also dimensionless. To answer the question, I've never seen a BMI with units attached, so I would guess that it is a dimensionless number, as produced by the first equation. But I have no source. -- Coneslayer (talk) 11:19, 18 July 2008 (UTC)[reply]
Body mass index is an index, not a measurement. That is why it doesn't have units. Unlike unit measurements where 1 meter is 1 meter regardless of who is measuring it, BMI is a statistical index based on the population. If anything, it could have been designed as a percentile. However, a simply index was chosen which is easily turned into a percentile. -- kainaw™12:08, 18 July 2008 (UTC)[reply]
BMI doesn't depend on the population, it's a number calculated from measurable properties of a person. What's considered healthy might depend on the population, but the number itself doesn't. The reason it isn't usually seen with units is simply because the units are always metres and kilograms, so there is no need to state them. --Tango (talk) 21:24, 18 July 2008 (UTC)[reply]
BMI can be considered either as dimensionless or as having the unit kg/m^2. Take your pick between these two views:
(1) A person's BMI has the unit is kg/m^2 regardless of whether it's written. Dimensionless numbers result from comparing too identical types of quantities, such as two lengths or two velocities, so the units used in measurement do not affect the dimensionless number. For the body mass index, on the other hand, only kg and m can be used without introducing conversion factors.
(2) If we make the simple assumption that a person's BMI is (weight/height^2)/(1 kg/m^2), the BMI would be unitless, and the index is indeed almost always reported without any units. --Bowlhover (talk) 09:09, 19 July 2008 (UTC)[reply]
A Possible Method for Tachyon Formation and A Possible Method for Superluminal information transfer
Today while I was reading an article on tachyons, I suddenly thought about tachyon pairs appearing beside a black hole due to quantum fluctuations, and becomes "real" being sent by Hawking Radiation, which the article said "real" tachyons do not exist. Is this method of tachyon formation possible? please reply! And, I also thought that humans could create a machine that ejects multiple tachyons at different rates and places, and another receiver collects the tachyons, and "reads" their shapes and converts them into pictures or words that are understandable by humans. Perhaps, the sender may be able to send a line of tachyons coded with Morse code(special thanks to Morse!) like telegraph, and the receiver receives the data and decodes the pattern of tachyons into understandable symbols or words. Is this method of superluminal information transfer possible? Please reply!!! —Preceding unsigned comment added by Superwj5 (talk • contribs) 13:18, 18 July 2008 (UTC)[reply]
You realize that tachyons are hypothetical particles? That is to say, no one has ever seen one, and they may not exist, and if they do, we don't really know their properties. Could someone do this? Uh, maybe? But you're not going to get any kind of a real answer to that here, because you're essentially asking about science fiction. -- Captain Disdain (talk) 15:24, 18 July 2008 (UTC)[reply]
Also, your "questions" have more "I have a crazy theory" than "I have a question" to them. It makes it very clear that you are looking for discussion, not references. This is a reference desk. If you simply want to discuss your theories, there are thousands (if not millions) of discussion forums on the Internet just for that purpose. -- kainaw™15:31, 18 July 2008 (UTC)[reply]
I think you're being confused by two different uses of the word "real" in physics. Tachyons are not real in the same sense that Santa Claus is not real, whereas the particles in Hawking radiation are real in the sense that they're not virtual. -- BenRG (talk) 16:39, 21 July 2008 (UTC)[reply]
hypopthetical global warming
Hi. This is not homework, and is viewed from a theoretical standpoint. Consider 17°C (30°F) of global warming. What would happen to Earth's Flora and Fauna, its microorganisms, and humanity? What if this happened in 10,000 years? 4,000 years? 1,000 years? 600 years? 500 years? 300 years? Would we survive? Could negative feedbacks eventually bring on a cooling trend? What would happen with 5,000 ppm CO2? What about 60 metres of sea level rise? Thanks. ~AH1(TCU)17:26, 18 July 2008 (UTC)[reply]
That sort of temperature rise would lead to a major mass extinction event. There was a minor one associated with a 6°C rise 65 million years ago, which is the sort of rise expected soon with global warming (and all the older official estimates have turned out to be underestimates). Perhaps humans would survive, I'm not sure. It would make a good disaster movie. Dmcq (talk) 21:01, 18 July 2008 (UTC)[reply]
It's worth considering that before you consider "Could negative feedbacks eventually bring on a cooling trend" you likely have to consider how you got 17°C rise in the first place (if a negative feedback does kick in, why didn't it kick in earlier? Or did it already kick in but we somehow managed to release such an extreme amount of CO2 that we still managed to achieve such a rise?). I'm not sure but I think our current knowledge re: such an extreme rise is limited since must studies are concentrated on what is expected with what we're doing now or may be doing in the future rather then what conditions may lead to such an extreme rise (according to the latest IPCC "IPCC indicate that average global surface temperature will likely rise a further 1.1 to 6.4 °C". Of course we know that if we do have such a rise, it would be catastrophic Nil Einne (talk) 07:34, 19 July 2008 (UTC)[reply]
One of the possible causes of the Permian-Triassic extinction event, the largest extinction in Earth's history, is a temperature increase of 10 to 30 degrees Celsius (see http://news.bbc.co.uk/2/hi/science/nature/4184110.stm). Although the cause of the extinction is still not known with certainty, the scientists who proposed the above-mentioned warming as a hypothesis presumably had evidence that a 10-degree rise in temperature can cause 80% of species to perish.
5000 ppm is 18 times the pre-industrial CO2 level. Earth's temperature rises approximately 3 degrees for every doubling of CO2 concentration, so 5000 ppm implies a warming of 12 degrees. Of course, positive and negative feedback systems would have a great impact in such an extreme climate.
As for sea level rise, http://merkel.zoneo.net/Topo/Applet/ is a crude interactive tool that displays geographical maps for any user-entered sea level increase.
Hi. Yes, IPCC predicts 1.4 - 5.8C of warming within 100 years, and 6C would still be catastropic as Six Degrees: Our Future on a Hotter Planet says 6C is all it took for the P-T extinction to occur, and please say if you're using C or F, and Fred Pearce's book With Speed and Violence: Why Scientists fear tipping points in Climate Change details that the Hadley Centre predicts upwards of 10C (21F) within 100 years. Thanks. ~AH1(TCU)18:32, 19 July 2008 (UTC)[reply]
Sorry about the 6C I'd been thinking of his lowest timescale of 300 years which considering there's lots of coal tars etc will be hard to avoid. I should really have stuck to the IPCC limit of 2100. However the IPCC does has 6C within its error range which is quite worrying. Dmcq (talk) 19:34, 19 July 2008 (UTC)[reply]
I would think the total amount of habitable land would be about the same. Portions of the tropics and coastal areas would become uninhabitable due to high temperatures or flooding, but, at the same time, vast areas of Canada, Greenland, Russia, Sweden, Norway, Finland, and even Antarctica, would become habitable. The greatest threat to humanity might be indirect, as competition for those new resources could lead to global war. StuRat (talk) 21:12, 20 July 2008 (UTC)[reply]
Peruvian tropical cyclones and the Humboldt current?
Hi. Why don't tropical cyclones ever occur in the southeastern Pacific? Yes, I know it's because the Humboldt current keeps the water there cold, even more so than in the South Atlantic, but what about during an El Niño? Wouldn't the water be almost as warm as the southwest Pacific? Or, is there too much wind shear? In a globally-warmed world, with stronger El Niños, would tropical cyclones develop there as in the South Atlantic? Or, does something else keep cyclones from forming there? Is it a high pressure system? If it is, then why when hurricanes in the Atlantic form occasionally where the Bermuda high should be, none form near the South American coast? Do Antarctic cold currents and winds keep the South Hemisphere too cold? Also, is the Humboldt current the main reason why the Galapagos islands are so diverse? Thanks. ~AH1(TCU)17:35, 18 July 2008 (UTC)[reply]
I could't find direct sources, but El Nino is defined by a surface temperature deviation of at least 0.5°C. The Humboldt current is about 7-8°C colder than one would expect water at this latitude to be. So even with El Nino going strong, the water is still quite cold. --Stephan Schulz (talk) 22:43, 20 July 2008 (UTC)[reply]
See this map. Even during the strong 1998 El Nino, the ocean temperature in the southeastern Pacific was only above the lower limit for hurricane formation, 28 degrees, north of 10 degrees south. Note that the ocean in the area was colder during a strong El Nino than the southwest Pacific was during a strong La Nina.
The second unfavorable condition preventing the formation of cyclones is indeed wind shear. See this paper, which addresses the issue of why tropical cyclones don't form in the southeastern Pacific.
This question probably just indicates my lack of understanding on CP-violation and 3-manifolds, but here it goes:
Let's say there was a group of flat-landers living on a Mobius strip, or if you like, a klein bottle. Now let's say one of the said flat-landers embarks on a journey around his universe. When the he returns, the other flat-landers find that his left and right sides have been switched, i.e. assuming flat-landers are anatomically similar to us, his heart is now on his right side. Of course to his point of view, his heart is on his left side, and left and right everywhere else is switched.
Now let's take this to a three dimensional universe on some kind of a generalized klein bottle. Another journeyman goes across the universe, this time with a bottle of kaons (Ignore in difficulties caused by their decaying and the likes.) When he comes back the kaons will violate CP-symmetry the other way now (and his heart would be switched too, I think). Would this be like having one side of a Mobius strip red and the other side blue, meaning there has to be a boundary somewhere, or could it prove that the universe is orientable? If I've got any of these facts or assumptions wrong, please let me know because I am trying to learn and I do not understand this stuff very well yet.
Forgive me if this is off-topic of your questions. I stopped reading after your assumption of the flat-lander's anatomy being switched. If you travel around a Mobius strip, you will not know you are doing so. You set off on a straight line. When you reach the point on the strip where you started - from the point of view of a 3-dimensional being - you are on the opposite side of the strip. Nobody was sitting around at your starting point will know you are there. You continue on another lap and return to the starting point and meet your friends. So, if the true circumference of the strip is 100m, you will claim it is 200m because you had no means of knowing you passed your starting point on the opposite side of the strip. -- kainaw™18:43, 18 July 2008 (UTC)[reply]
No, sorry Kainaw, you're taking the "paper strip" image too literally. A mathematical Möbius strip does not have any thickness; when you get around to where you started you do see your friends, but you are now oriented differently with respect to them. --Trovatore (talk) 18:50, 18 July 2008 (UTC)[reply]
Wow, Wikipedia really does have an article about everything. Although the article doesn't mention CP-symmetry, I'm guessing that no global distinction can be made for it as well. Now I have a new question: does anyone know if there are good reasons that the universe may be orientable or not. I realize it probably makes the physics cleaner if it is orientable, but maybe there is some evidence to the contrary perhaps? Anyways, thanks for the article Algebraist. Jkasd19:54, 18 July 2008 (UTC)[reply]
Zipcodezoo
Hello, Refdeskers! I hope this is the appropriate place to begin this discussion. I was wondering if any of you have an opinion on ZipcodeZoo. It's beginning to come to the top of the list on google searches for species and genera and thus is also beginning to show up on Wikipedia. There are about 190 pages on Wikipedia that mention or link to zipcodezoo [12]. Personally, I've found this resource to be unreliable to some extent. I believe it gathers data from various sources and presents it without a human eye looking over it, leading to situations where synonyms for species are wildly incorrect. Taxonomy is just as bad. See specific concerns at an archived discussion with WP:PLANTS: Wikipedia talk:WikiProject Plants/Archive18#ZipcodeZoo. I'd appreciate your thoughts on this. Is removal on sight acceptable? Hopefully with time it will become more reliable, but over the past year it hasn't changed much. --Rkitko(talk)23:50, 18 July 2008 (UTC)[reply]
Disadvantages of coilguns and railguns
What are the disadvantages of modern coilguns and railguns that need to be overcomed for possible infantry use? --Whuzatt23:52, 18 July 2008 (UTC)[reply]
The railgun page on wikipedia should give some insight. For larger applications, incredible amounts of energy is needed. launching projectiles also damages the tracks. Coolotter88 (talk) 02:17, 19 July 2008 (UTC)[reply]
The amount of energy needed is currently a technological hurdle. There needs to be improvements in portable energy before e-mag cannons see widespread use. Railguns can deliver more force, but the friction cause by the projectile sliding against the rails causes a lot of damage. Maybe if there were a way to coat the rails or the projectile in conductive plasma, that might solve the problem. ScienceApe (talk) 17:12, 19 July 2008 (UTC)[reply]
Then there is the magnetic field generated, which could permanently damage nearby equipment or make it temporarily inoperable. The magnetic pulse might also be detectable by the enemy (for them to use in target-acquisition or as a warning to take cover). StuRat (talk) 20:54, 20 July 2008 (UTC)[reply]
July 19
Obesity
Apart from being less likely to starve to death during the next famine, are there any health benefits of being overweight? --Carnildo (talk) 04:15, 19 July 2008 (UTC)[reply]
I don't know about obese people (especially extreme obesity), but slightly overweight people tend to have slightly better survival outcomes with various forms of cancer and modern treatments IIRC. On the other hand, being overweight (and especially sedentary) tends to increase the risk of getting cancer so... (And admitedly some studies seem to show the opposite e.g. [13] which suggests a lower survival rate in Chinese women) Nil Einne (talk) 07:24, 19 July 2008 (UTC)[reply]
I don't know of any real good effects of being obese. The article lists all these as negative factors though:
A recent (and controversial) study in JAMA suggests your final statement may not be accurate, CycloneNimrod. They conclude that "The net result [of their study] was that overweight was associated with significantly decreased all-cause mortality overall." Specifically, being overweight gives an apparent protective effect against causes of death such as tuberculosis, emphysema, pneumonia, Alzheimer's disease and injuries, but an increased risk of cardiovascular disease, some cancers, diabetes and kidney disease. When you balance the two out, the chubbies appear to be in the black. To be fair, the study didn't control for smoking and preexisting illnesses, so it could be skewed, but it does give one, ahem, food for thought. Rockpocket20:02, 19 July 2008 (UTC)[reply]
Obesity is bad, but there are potential benefits to being slightly overweight. Nil Einne gives one above, and I believe there are others, but I'm not sure what they are. --Tango (talk) 17:51, 19 July 2008 (UTC)[reply]
While obesity per se presumably has little biological selective advantage, remember that the ability to store large amounts of fat when food is plentiful is of great selective advantage--at least before modern times when food is abundantly available all year for many people. Then this physiological ability becomes non-adaptive. Seen in this light it is easier to see why becoming fat is so common, and why losing weight is so very difficult. Evolution has equipped us with the strong desire to eat greedily far beyond our immediate needs, because in the past it increased survival, and for women, the likelihood of having and nursing strong children.--Eriastrum (talk) 23:04, 19 July 2008 (UTC)[reply]
We've already touched on obesity preventing people from starving to death, but note that such starvation isn't always due to a lack of food. Many diseases cause a drastic loss of weight, which can be fatal, especially if not treated (say with a glucose IV).
Hypothermia has been mentioned, but I disagree with the statement that obesity is no help when wearing clothing. Obesity may be especially helpful when waiting in cold water for a rescue, for example, whether wearing clothing or not.
Obesity may also decrease the rate of drowning, because fat floats, and people with more fat float better. They esentially come with their own floatation device.
Then there is the absurd effect that some studies might indicate a reduction in the death rate from many other causes which seem unrelated to obesity, like homocide. The reason is that obese people are likely to die earlier, thus having less opportunity to be murdered. StuRat (talk) 20:49, 20 July 2008 (UTC)[reply]
AIDS Cure Deadline?
Despite the obviously long term nature of the search for an AIDS cure/vaccine, has anyone been quoted regarding any theoretical deadline by which we can expect it by? Or are things still in the "It'll be here when it gets here" stage? —Preceding unsigned comment added by Kenjibeast (talk • contribs) 04:40, 19 July 2008 (UTC)[reply]
I suspect that one day, potentially within my lifetime, there may be a cure (whether in the form of a vaccine or not). For now, though, I don't think anyone has much idea of when or how it'll be achieved. As Carnildo posted, that article may give a few hints. —CycloneNimrodTalk?10:09, 19 July 2008 (UTC)[reply]
Carnildo, is there reason to believe that it's impossible? Or perhaps I'm really asking if there is any consensus among scientists in the field that it might be impossible. Either way! I'm asking because from what I understand, there are promising discoveries being made, even if an actual cure still hasn't been found. It seems to me that at least some progress is being made, but is that just an illusion in terms of whether knowledge about HIV and fighting it has appreciably increased within the last, say, five years? -- Captain Disdain (talk) 10:27, 19 July 2008 (UTC)[reply]
It's definitely not impossible. For example, we could create a nanomachine, that could destroy the virus. Nanomedicine if you will. It's beyond our current level of technology, but it's possible. Incidentally, such a nanomachine would be capable of curing other RNA viruses like the common cold. ScienceApe (talk) 17:15, 19 July 2008 (UTC)[reply]
You rarely have anything more than guesses about the timescale for new inventions. The process basically involves trying lots of different things until you eventually find one that works (the skill comes in narrowing down which things to try). Since you don't know which one is going to work, you can't say how long it's going to take to find it. It's difficult to even give an expected time without knowing how many possible things there are to try (which is pretty much infinite) and how many of them are going to work (which could be anything from none to infinite). --Tango (talk) 17:49, 19 July 2008 (UTC)[reply]
Alcohol dimer formation
It is a known fact that organic acids form dimers by hydrogen bond attachment of the carbonyl group oxygen in one acid molecule (say molecule A) with hydroxy group hydrogen in another acid molecule (say molecule B) and the carbonyl group oxygen in B attaches with hydroxy group hydrogen in A as seen here:[14]. In organic alcohols, though, the hydrogen in a molecule(say C) attaches with the oxygen in another molcule (say D). Is the remaining oxygen of molecule C capable of attachment with the hydrogen of D (to form a quasi-acidic two way dimer), or, will the oxygen of C and hydrogen of D always attach with the hydrogen and oxygen of some other molecule? Leif edling (talk) 06:37, 19 July 2008 (UTC)[reply]
A dimer is possible, as is a trimer (3 in a ring).
A hydrogen from C will undoubtedly be hydrogen-bound to the oxygen in D, but I think it would be more likely for the oxygen of D to be bound to a hydrogen from another molecule, E, rather than C, in the liquid state. This way, a network of hydrogen bonds can be formed similar to that which water forms, but with less intensity. I've never heard of a single OH group simultaneously being an acceptor and donator to only one other OH group. --Russoc4 (talk) 14:49, 19 July 2008 (UTC)[reply]
Yes a dimer is possible, but mostly unlikely - reason - four membered rings are much less stable than 6 membered ring - note in carboxylic acid dimers the 'ring' structure' is hexagonal (though there are 8 atoms involved)87.102.86.73 (talk) 16:13, 19 July 2008 (UTC)[reply]
It shows that for n-hexdecanol in the solid the molecules form with OH groups in a line eg:
H
/
CCCCCCCCCCCCCCCCO
CCCCCCCCCCCCCCCCO
H \
\ H
OCCCCCCCCCCCCCCCC
OCCCCCCCCCCCCCCCC
H /
/ H
CCCCCCCCCCCCCCCCO HOxxxxxxxxxxxxxx
CCCCCCCCCCCCCCCCO
H \
\ H
OCCCCCCCCCCCCCCCC
OCCCCCCCCCCCCCCCC
H /
/ H
CCCCCCCCCCCCCCCCO etc etc
C represents CH2 etc, my rough interpretation.. as you can guess where the H bonds will be you can see the zig-zag formation.. This is only one layer - you might guess that the next layer will be reversed - so that the alcohol on top takes the position indicated by HOxxxxxxxxxxxxx'
' ...87.102.86.73 (talk) 15:35, 19 July 2008 (UTC)[reply]
I'll guess and say that I'm certain that the type of arrangement above is that which occurs and not a dimer. Though a dimer may still form temporarily in the liquid.87.102.86.73 (talk) 16:15, 19 July 2008 (UTC)[reply]
Aspartame lead to drowsiness?
Why is it that when I drink diet drinks with aspartame it makes me drowsy, like when you've been awake for too long and your consciousness begins to lapse? Is it a known side effect? What causes this? --antilivedT | C | G08:27, 19 July 2008 (UTC)[reply]
Yea I've looked at that, doesn't really mention my effect. This is not exactly medical advice since I've already stopped drinking them; I'm just curious on why it affects me in this way while other people are seemingly fine taking it. --antilivedT | C | G10:32, 19 July 2008 (UTC)[reply]
One extremely far-fetched reason could be that the aspartame is breaking down into methanol in amounts significant enough to cause drowsiness. It's far-fetched because the amount of aspartame in your drink is probably minuscule, and certainly not enough methanol would be created to have any noticeable CNS depression. --Mark PEA (talk) 12:44, 19 July 2008 (UTC)[reply]
Do you commonly drink diet caffeinated drinks, but are now drinking caffeine free drinks? It could be a psychological effect if your body/mind has paired drinking caffeinated drinks with the flavor of aspartame, but has now suddenly been subjected to caffeine free drinks of the same or similar flavor. --Russoc4 (talk) 14:54, 19 July 2008 (UTC)[reply]
Or, similarly, you used to drink the non-diet versions and simply have a lower blood sugar level now - drowsiness and loss of concentration are symptoms of hypoglycaemia. --Tango (talk) 17:43, 19 July 2008 (UTC)[reply]
Hmm not really, I don't usually drink caffeinated drinks at all. And even so diet Coke has caffeine is well so if anything it should give me a "boost" as well. I still get this if I drink both diet and non-diet soft drinks at the same time or drinking it while having a meal, so I'm pretty convinced it's the aspartame or anything else that's different between diet and non-diet soft drinks. --antilivedT | C | G23:19, 19 July 2008 (UTC)[reply]
You could be allergic to aspartame, I suppose - you would need to talk to a doctor if you want to find out for sure. --Tango (talk) 00:17, 20 July 2008 (UTC)[reply]
No. (Which should be fairly obvious from the scheme itself—if the dominant trait was always "better", why would there be recessive traits at all?) --98.217.8.46 (talk) 19:07, 19 July 2008 (UTC)[reply]
It's not "pretty subjective" as to whether dominants are always better. The answer is "no". As to whether some dominants are better than some recessives, sure, and all other combinations. There are some dominants that will kill you right out, there are some recessives that will kill you right out. --98.217.8.46 (talk) 19:35, 19 July 2008 (UTC)[reply]
I can't think of a recessive allele that "will kill you right out", if you inherit it in a recessive manner (i.e heterozygous with a non-harmful dominant allele). Could you give an example? Rockpocket19:42, 19 July 2008 (UTC)[reply]
I was referring to two recessives. I would be very surprised if there weren't some heterozygote combinations that had non-harmful dominants that were fatal to the organism, though they would be rare for simple obvious evolutionary reasons. --98.217.8.46 (talk) 21:13, 19 July 2008 (UTC)[reply]
Assuming "kill you right out" means before you can reproduce (which is what is significant for evolution), then the only way you could get a allele that would kill you right out with only one present would be by mutation. Mutations often kill the organism pretty quickly - usually before birth, as a miscarriage. If it's having an effect, though, then surely it isn't recessive, by definition? Part of its function may be recessive, but the bit that's killing you clearly isn't. --Tango (talk) 21:31, 19 July 2008 (UTC)[reply]
That was my reasoning too, a dominant would have to be a de novo mutation in the germline and a recessive, by definition, wouldn't kill you right out. However, it is probably correct that the are scenarios where two recessive alleles (at different loci) could combinatorially "kill you right out" if inherited, one from each parent. I guess it would be a form of additive haploinsufficiency. I can't think of any example of that either, but I'm sure there are some. Rockpocket22:08, 19 July 2008 (UTC)[reply]
I hadn't thought of that. I've never heard of anything like that, but I can't see any reason for it not happening. --Tango (talk) 00:15, 20 July 2008 (UTC)[reply]
Dominance is relative. For example, a dominant allele for a receptor will be one that has a dominant function. A normally functioning receptor will have a dominant function in comparison with one that lost its regular function. In this case, the allele that encodes the normal receptor is the dominant allele and it may well be "better" (because we may need that receptor to function properly). However, another receptor allele may encode a receptor that is constitutively active (it keeps signaling an never stops). This allele will be dominant to the normally functioning receptor. However the regular allele may well still be "better" (because a always active receptor could be just as problematic as a never active receptor). In this case dominance does not equal better. But there are times when either lack-of-function and gain-of-function are better than the regular-function alleles, it all depends on what the environment is the genes are working in. Rockpocket19:42, 19 July 2008 (UTC)[reply]
Summarizing: the dominant trait tends to be the better one, for the simple reason that if weren't the better one it probably would have been selected out, whereas recessive alleles are subjected to less selection pressure. But the question asked if it's always better, and the answer to that is certainly no. --Trovatore (talk) 21:56, 19 July 2008 (UTC)[reply]
If I'm not mistaken, the current model of the universe is that it will continue to expand until even galaxies burn up and fly apart.
My only thought is of black holes. From what I understand, black holes do evaporate at a rather slow rate (see Black_Hole#Evaporation, but that currently the Cosmic background radiation is easily enough to offset this. However, in a situation in many tens of trillions of years, would the Cosmic background radiation have decreased in magnitude enough that it would allow very slow disintegration of the black hole? In this case, there would be essentially nothing left of the universe.
This, of course, excepts any circumstance which we cannot foresee (e.g., another big bang occurring very far away, unexpected reactions from dark energy). The Evil Spartan (talk) 19:50, 19 July 2008 (UTC)[reply]
I can't source it at present, but a cosmology talk I went to a few years ago featured a (very long) future epoch in which most of the mass of the universe was in very slowly evaporating black holes. There won't be nothing left after this, of course (the holes don't evaporate to nothing; that would violate energy conservation), but they'll be nothing very interesting. Algebraist19:54, 19 July 2008 (UTC)[reply]
See Heat death of the universe. Under your scenario (which is one of the likely ones), you would end up with nothing but radiation and individual sub-atomic particles (which ones isn't certain - protons may or may not decay over extremely long timescales) just floating around doing nothing much at all. This is called heat death. --Tango (talk) 21:25, 19 July 2008 (UTC)[reply]
Evil Spartan: your first sentence seems to be referring to the big rip. It is one of the posited fates of the universe, but the consensus seems to be that the ironically-named heat death is the most plausible. As for whether the CMB will eventually become cool enough for Hawking radiation to occur, the answer is yes, as the CMB has already cooled from 3000 degrees Kelvin to the current 2.7 degrees. A calculation using the equation :Failed to parse (SVG (MathML can be enabled via browser plugin): Invalid response ("Math extension cannot connect to Restbase.") from server "http://localhost:6011/en.wikipedia.org/v1/":): {\displaystyle T={\hbar\,c^3\over8\pi G M k}\,}
, found here, shows even a black hole of 100 solar masses requires the CMB to be lower than a few nanokelvins in temperature before its mass starts decreasing. --Bowlhover (talk) 09:11, 20 July 2008 (UTC)[reply]
I think many people are confused by the exponential growth of the scale factor in the Lambda-CDM model. Exponential expansion isn't nearly as catastrophic as it sounds. It won't rip the Milky Way apart no matter how much time passes. The fate of the galaxy in this scenario is plain old 19th-century heat death. In the big rip scenario (which is probably wrong) the expansion is faster than exponential—in fact the scale factor diverges to infinity in a finite time. -- BenRG (talk) 17:14, 21 July 2008 (UTC)[reply]
I did, but I am not seeing stuff I need: it has stuff related to colonizing the solar system (or a galaxy a general), but not what I am looking for which is "a manual for colonization of a random planet (or system) out there".--Piotr Konieczny aka Prokonsul Piotrus| talk 02:30, 20 July 2008 (UTC)[reply]
If by "random planet" you mean you want one manual suitable for any planet, then you won't find one, since different planets require different methods of colonisation. For specific planets, there's plenty of information out there, our articles linked to in the Space colonization article should get you started. --Tango (talk) 02:38, 20 July 2008 (UTC)[reply]
Assuming we're thinking of the same thing, yes (as an aside, the common name is wrong and seriously misleading). I don't think the OP's question has an answer. Algebraist23:21, 19 July 2008 (UTC)[reply]
I agree that the question is misleading. What they are really asking is what the "____ rating" is at gasoline stations that tells you how likely it is that the car engine will "knock". However, as few modern cars have trouble with knocking any more, engine performane isn't likely to be an issue unless you buy poor quality gasoline at some nonane gas station. StuRat (talk) 20:29, 20 July 2008 (UTC)[reply]
Effects of a Small Ice Age on Hay Fever Sufferers
Lately, I have heard discussion regarding the possible production of a new ice age due to the effects of global climate change.
Purely theoretically, how would an ice age effect Hay Fever sufferers? That is how would hay fever, being a seasonal disease, react to a drastic reduction in temperature. Specifics would be appreciated regarding the effect this new ice age would have on the various plants that cause hay fever. Would the cold affect pollen production, etc. —Preceding unsigned comment added by Kenjibeast (talk • contribs) 22:03, 19 July 2008 (UTC)[reply]
Different hay fever suffers are affected by the pollen of different plants. A significant change in temperature will change which plants grow where and at what times during the year. That will probably makes thing better for some suffers and worse for others (including some that weren't really sufferers before if new plants start growing where they live). It may well be better for everyone for a short time until the plants adjust, since there will simply be less plants growing successfully. --Tango (talk) 00:14, 20 July 2008 (UTC)[reply]
A shorter spring and colder summer would likely reduce the over-all pollen in the air. Then again, it might get worse depending on local ecology and how exactly your weather is being impacted. For example, some desert areas might get more rain encouraging more plant growth. ---J.S (T/C/WRE) 03:28, 20 July 2008 (UTC)[reply]
I would expect it to have a similar effect on the analagous structure in the female anatomy (you can decide whether to take clitorally all the things I say). StuRat (talk) 20:21, 20 July 2008 (UTC)[reply]
Is the universe's expansion speeding up or slowing down? I always thought it was slowing down but now someone has confidently asserted to me the opposite. I have looked at the wiki page on Expansion of the Universe but I don't think it says there (a lot of it was quite technical).
And yes, it is used to raise blood pressure in patients with dangerously low levels, either as an IV or given orally (say as a broth). Low blood pressure is a common result of dialysis, for example, and this is a common treatment. StuRat (talk) 20:10, 20 July 2008 (UTC)[reply]
One of the main components of olive oil comprises the majority of Lorenzo's oil, a substance which is used in conjunction with a controlled diet to treat adrenoleukodystrophy. The oil is still being evaluated by the FDA, but it's discovery was impressive and effective enough to merit the production of an academy award nominated film. --Shaggorama (talk) 06:09, 21 July 2008 (UTC)[reply]
Most drugs have side effects. It might be a good idea to look at the article for the specific drug you are interested in. Or consulting a doctor, if this relates to a specific medical concern.--Fangz (talk) 13:17, 20 July 2008 (UTC)[reply]
You may also want to read Statins. While not without side-effects you'll probably come across a lot of talk discussing statins as a sort of wonder drug given their general relatively high safety while having a relatively high success in lowering cholesterol. One concern, as is not uncommon in treating any condition diet related is that it's generally far better to modify/improve one's diet rather then to go on drugs, not just to avoid side effects of drugs, but also because of the other likely benefits of an improved diet Nil Einne (talk) 18:10, 20 July 2008 (UTC)[reply]
Yes, the lack of a good diet is a concern. I'd even go further and argue that some people may allow their diets to significantly worsen if they think some "miracle drug" will solve all their health problems for them. StuRat (talk) 20:02, 20 July 2008 (UTC)[reply]
asteroid - earth impact
How precisely can we detect in advance menacing asteroids that might crash on earth? How do the predictions improve as the object approaches? At what moment are we able to pinpoint an area where it will crash? Is there a range of speeds asteroids find themselves in, do different speeds change the force or probability of an impact? Could one bounce off the atmosphere if it arrived a low angle? I read Asteroid impact but couldn't find the answers. Thank you. 190.190.224.115 (talk) 14:10, 20 July 2008 (UTC)[reply]
Using radar, we can get extremely precise measurements, often a long time in advance. I think the asteroid needs to be quite close to get such measurements, but there are often close approaches to Earth before the one that could result in a collision, so we can take the measurements then and project the path forwards. Where it will hit depends on the exact time of the collision. Working out the thin path that the asteroid could hit is quite easy, since it just depends on the direction the asteroid is coming from, working out where on that path it will hit requires exact timing, and that requires much more accurate measurements. We would probably still get that some time in advance. I would expect asteroids can bounce off the atmosphere, although I'm not sure it's very likely - there's probably a very narrow range between where it becomes shallow enough to bounce and where it misses entirely. --Tango (talk) 17:28, 20 July 2008 (UTC)[reply]
The difficulty isn't just in taking precise measurements of location, direction, and velocity, but is complicated by the fact that asteroids can change direction. This change, while slight, can significantly affect whether one will hit the Earth several passes later. Changes in direction are often due to interaction with other objects, but not always in a predictable manner. For example, while passing a planet or the Sun, tidal forces or sunlight can melt ices, which can then be vented. Those can change both the mass and trajectory slightly. StuRat (talk) 19:58, 20 July 2008 (UTC)[reply]
Can someone help me in my own noble pursuit of all the world's (scientific) knowledge?
What would be the proper order to read your science articles so I can become a scientific personality with a steel trap mind? I mean someone says " .... my milkman, 1846, berylium, and the tenth law of thermodynamics?" I would immediately reply "My good man, your statement about the nonexistant 10th law of thermodynamics strikes I, a well known intellectual powerhouse in the esteemed scientific community, as peplexing and oddly prophetic. For it has been determined, by a barrage of outside the box labrotory research, that the math, using a newly, sometimes controversial property discovered by a still top secret learning facility, is indeed correct. Your milkman will discover 6 more laws of thermodynamics! ]:)
You can read them in any order. Science does not have a starting point. You study. If you find something that you do not understand, you study that. If that leads to something you do not understand, you study that. You continue until you understand the first thing you were reading. As for being respected... you will need a PhD. Make a list of the top 100 scientists of all time. You will have a handful that lived before the invention of the PhD (so they don't have one). You will have a couple that didn't get a PhD for one reason or another. Then, the majority will have a PhD. Why? If you are too stuck up or lazy to get a PhD, why should all those who got theirs want to spend their time listening to you? -- kainaw™19:34, 20 July 2008 (UTC)[reply]
PhD is certainly the qualifier. All those man-hours put into achieving a doctorate, shows that you are a dedicated scientist in your field, and worth listening to. No one would care about what Miss Teen South Carolina thinks of blackholes or general relativity, but lots of people listen when Carl Sagan or Michio Kaku talk about them, because they know what they are talking about. ScienceApe (talk) 20:38, 20 July 2008 (UTC)[reply]
I don't think that's true at all. A PhD is nearly a requirement if you want a career in academia, but respect in academia is almost entirely a function of what you publish. Anyone who does look at your educational history will be more interested in the schools—a BA from Berkeley is worth a lot more than a PhD from Columbia Pacific University. I think professional astronomers appreciate Sagan's popularization of astronomy, but I don't think they'd rate his scientific work as especially memorable. Kaku I think is little short of a crackpot. Jack Sarfatti is an outright crackpot, and he has a PhD in theoretical physics from UC Riverside. There's a popular perception that anyone who can get a PhD must know what they're talking about, but sadly it isn't true. Anyone can get a PhD if they try hard enough; most people are just smart enough not to bother. -- BenRG (talk) 12:37, 21 July 2008 (UTC)[reply]
If you want my, totally biased advice: a great way to get a very generalist understanding of science is not to study science itself, but to study the history of science. If you read through the article on History of physics and took the time to look into the sub-articles linked to there, you'd have a great, great understanding of physics for practical, conversational purposes. Could you set up an experiment yourself? No. That takes formal training for the most part. Could you carry on a conversation about the relevance of the expanding universe? Yes indeed. Could you probably find yourself with a lot to say on the topic of string theory, relativity, and the philosophical implications of quantum mechanics? Yes you could—and frankly, if you aren't actually going to be whipping out your calculator right there, I'm not sure trying to parse through all the equations is going to get you very far anyway. Just my two cents. --98.217.8.46 (talk) 00:29, 21 July 2008 (UTC)[reply]
Having a PhD is not a requirement for being smart, or a good scientist. To be a good scientist, it is all about the mindset and philosophy you are in. A PhD is merely a good sign of one. Freeman Dyson is a famous physicist and Planck Medal winner who hates PhDs. Just wanted to get that in there. Mac Davis (talk) 03:43, 21 July 2008 (UTC)[reply]
You're only going to read (with dedication) if you're interested, and you'll talk more about subjects you're interested in as well. I'd suggest focusing your study on areas that fascinate you and follow tangents as they arise. You might also want to start brushing up on lay-science magazines; it sounds like you're interested in physics, so I'd suggest something like Scientific American or Popular Mechanics. --Shaggorama (talk) 06:24, 21 July 2008 (UTC)[reply]
I for one don't like popular science magazines at all. They just leave you "OK, black holes are like vacuum cleaners of space, but how does it really work.". Reading Wikipedia, for example, is much better. —Bromskloss (talk) 15:02, 21 July 2008 (UTC)[reply]
Don't forget to regularly read the Wikipedia Science reference desk (like you are now), I learn lots of new things everyday in just a 5 minute visit to this place. --Mark PEA (talk) 15:12, 21 July 2008 (UTC)[reply]
How does the odor of rotten food make us gag?
I suppose the "why" is a survival mechanism, so that we won't ingest foods that have been taken over by possibly noxious or even toxic bacteria. (Please correct me if I'm wrong.) What I don't understand is how this works. I had to get within arm's length of some overage potatoes today, last week it was a (refrigerated) leftover portion of baked tilapia. My few experiences with natto also made me gag almost to the point of retching. The pharyngeal reflex page wasn't much help, though I've also had this difficulty when clenching my teeth around those cardboard-covered dental X-ray film holders. Advice on avoiding this reaction would be helpful, but I'll settle for understanding it better. -- Thanks, Deborahjay (talk) 19:30, 20 July 2008 (UTC)[reply]
Yes, evolution is certainly why. As for how, I don't think it's anything mysterious. Your nose detects various chemicals in the smell and sends the signals to the part of your brain that analyzes the info. It compares it to a list of chemical combinations it recognizes as "rotten food" and sends the appropriate response to your body. That list of chemical combinations recognized as rotten food is somewhat interesting, though. It's partly inherited, but also partly learned. If you've ever eaten a food that had gone bad and then made you violently ill, let's say eggs, that may very well cause all eggs, fresh or not, to be recognized, from then on, as "rotten food". StuRat (talk) 19:49, 20 July 2008 (UTC)[reply]
The "how" is a involuntary muscle spasm and an emotional reaction. As with many involuntary reactions you can learn to suppress it, if you for some reason have a need. Garbage men learn that trick fairly quickly, I'd bet. ---J.S (T/C/WRE) 00:09, 21 July 2008 (UTC)[reply]
Actually despite what StuRat might think, the mechanism behind the gag reflex in response to certain odors is mysterious. The reason is that it appears to be largely innate, and not learned. That means that there is some genetically hard-wired neural network that encodes the odor-to-behavioral response. This type of innate response to odors is not unusual in animals, but they typically detect such odors with their vomeronasal organ which projects neurons directly to regions of the brain that mediate innate responses. The problem is, humans do not have a vomeronasal organ. Which means we detect the odors through or main olfactory system or one of the mysterious olfactory sub-system such as the septal organ or the Grüneberg ganglion (these are so mysterious, in fact, we don't have an article on them). Yet the neurons in the these systems project to cortical regions and don't appear to mediate innate responses. So the answer is that no-one really knows how certain smells appear to be innately aversive in humans. Rockpocket01:42, 21 July 2008 (UTC)[reply]
This isn't sourced, but I don't think I agree that it's not learned. Have you seen game shows like Fear Factor where the contestants have to eat century egg? I enjoy an occasional one "fresh" (haha, fresh century egg) out of the shell, as do many Chinese, but the people on the shows always gag. So in some ways, it has to be at least partially learned. --Wirbelwindヴィルヴェルヴィント (talk) 14:54, 21 July 2008 (UTC)[reply]
Blowing up nuclear powered vehicles
Lets say a nuclear powered vehicle like an aircraft carrier or a nuclear sub is attacked and destroyed with conventional weapons. Would the vehicle explode in a nuclear explosion, or would the explosion be no different than a similar conventional vehicle blowing up? Would there be radioactive contamination? ScienceApe (talk) 20:33, 20 July 2008 (UTC)[reply]
It's very hard to start a nuclear explosion (fission or fusion), and virtually impossible to do so with reactor that is designed specifically to avoid that occurrence. You'd get somthing like a dirty bomb, just dispersing all that nuclear material as a contaminant not trigger any further nuclear reaction. DMacks (talk) 20:36, 20 July 2008 (UTC)[reply]
(ec) There would certainly not be a nuclear explosion -- the fuels in such a vehicle are not weapons-grade in the first place, and even if they were, making a nuclear explosion is difficult; it requires very fussy design. Not gonna happen by accident. Radioactive contamination is certainly plausible -- I don't know what if any steps have been taken to prevent that in a war scenario and would be interested in finding out from someone who know --Trovatore (talk) 20:37, 20 July 2008 (UTC)[reply]
Actually US nuclear subs run on 93% enriched uranium, I do believe (and this article seems to claim such as well). It's not uncommon for small propulsion reactors to run on HEU—you get a lot more energy out of a lot less material that way (most research reactors used to run on HEU until somebody figured out that was a very bad idea). But no, you wouldn't get a real nuclear explosion, even with that fact being true, though you could get secondary explosions—e.g. inadvertent generation of hydrogen gas, that mixes with oxygen, that ignites, and spreads a lot of nasty stuff all over the place. You could imagine the fuel melting and forming a critical mass or two on the bottom of the reactor, which would result in neutron fluxes and maybe very tiny explosions but that's about it. --98.217.8.46 (talk) 21:40, 20 July 2008 (UTC)[reply]
Yes. ICF contamination is just from the material holding the reactor together, mostly. An actual fission reactor is constantly producing highly radioactive substances in great quantity. ICF has very mild contamination risk compared to fission. --98.217.8.46 (talk) 21:40, 20 July 2008 (UTC)[reply]
I question the "great quantities" part. Certainly the quantity is less than or equal to the mass of nuclear fuel lost during the reaction, which is quite low. StuRat (talk) 03:39, 21 July 2008 (UTC)[reply]
Yes, but the reaction products typically have much shorter half-lives, and therefore are much more radioactive, than the fuel. So while the quantity might not be large as measured in kilograms, it's a lot as measured in curies (or, more modernly, Bequerelsoops, I guess it's becquerels, but who really knows what those are?). --Trovatore (talk) 03:51, 21 July 2008 (UTC)[reply]
And I was referring to it relative to the ICF as well. A fission reactor contains far greater quantities of far nastier poisons than something that is only getting somewhat irradiated by a bunch of neutrons would. I am not trying to be anti-fission here, just pointing out that the production of rather nasty waste is an inevitable side-effect. ICF will irradiate its containment structure with neutrons which should induce some radioactivity but it's not going to be anything as bad as actual fission products. --98.217.8.46 (talk) 17:08, 21 July 2008 (UTC)[reply]
Depending on the details of the attack, it's quite possible that the reactor would survive intact (probably not watertight, but recoverable intact). Large metal objects have survived remarkably close to nuclear explosions. If the explosion was some distance away from the vessel, and ideally with the large bulk of the vessel between it and the reactor, then you might well expect the reactor (which is very heavily constructed indeed) to be ejected intact and deposited on the sea floor as a (warped, leaky) whole. -- Finlay McWalter | Talk20:53, 20 July 2008 (UTC)[reply]
Seagull dawn chorus of squawks
Why do they make so much noise as soon as it starts getting light in the morning? I looked out of my window today after they woke me up and saw them just flying around squawking loudly at each other. —Preceding unsigned comment added by 90.242.57.76 (talk) 20:51, 20 July 2008 (UTC)[reply]
Our dawn chorus article says that songbirds start to sing at dawn, often for territorial reasons. Less melodious, but the seagulls are doing the same. If you're in the UK/Europe, the seagulls have young in their nests at the moment so the parents are defensive. Watch out, because they sometimes circle and threaten to dive-bomb you. Itsmejudith (talk) 22:34, 20 July 2008 (UTC)[reply]
There is a Herring Gull nest on my roof this year. When it gets to about 4am, the chick is all "cheep! cheep! cheep! cheep! cheep!" whilst the mother (or father) gabbles/clucks away softly. It goes on all day - unless the chick is napping. The early-morning squawking gulls may also be on the look out for anything edible that has found its way onto the street overnight. When a gull spies food, it generally loudly announces the fact - which starts off a chain reaction of squawking amongst any other nearby gulls. --Kurt Shaped Box (talk) 23:26, 20 July 2008 (UTC)[reply]
Why would they announce it, knowing that this causes all the other gulls to try to steal their food ? Not the brightest, are they ? StuRat (talk) 15:34, 21 July 2008 (UTC)[reply]
I don't know for certain - but I suspect that any gull discovered feeding at a significant find without first notifying the rest of the flock will be on the receiving end of some heavy 'social pressure'. OTOH, the gull that spots the food might merely be giving a (fruitless) warning to the rest of the flock to stay away from his find... --Kurt Shaped Box (talk) 16:30, 21 July 2008 (UTC)[reply]
That said, you want to take safety precautions like making sure not to short the battery. Theres about a thousand different things that could go wrong in this process. If you are not an expert, please make sure to consult with one before doing anything crazy. In particular, do NOT short the battery in order to get current through the wire. EagleFalconn (talk) 14:56, 21 July 2008 (UTC)[reply]
Microwave oven
Can someone explain briefly (without too much technical or scientific lingo) why you can't place metal / aluminum foil / etc. in a microwave oven ... and what exactly would happen if you do? Also ... why is it that food tastes "different" when cooked in a microwave oven versus a conventional oven? Thanks. (Joseph A. Spadaro (talk) 02:48, 21 July 2008 (UTC))[reply]
See Microwave_oven#Dangers for the answer to your first question. The short-short version is that a piece of metal will act like an antenna, converting the microwaves into electricity. Depending on the shape, size, etc of the metal, that can cause various problems. Metal twist-ties often catch on fire, for example. APL (talk) 03:19, 21 July 2008 (UTC)[reply]
That's interesting. Hmmmmmm. Do we have any technology that takes advantage of this phenomena of metal turning microwaves into electricity? ScienceApe (talk) 03:37, 21 July 2008 (UTC)[reply]
Sort of. Obviously making microwaves then converting them back to electricity would use more energy than it would produce. However, special metallic foils are used under food to absorb microwaves and turn them into heat, to toast the food from underneath. StuRat (talk) 03:45, 21 July 2008 (UTC)[reply]
There are also various plans (and when I say plans, I mean vague ideas that may or may not have had a 1/10,000 scale prototype made so far) to do things like power spacecraft with microwave lasers, or use microwaves to "transmit" electricity without wires - see microwave power transmission. Confusing Manifestation(Say hi!) 04:16, 21 July 2008 (UTC)[reply]
But a simpler answer to the question of whether we have technology taking advantage of this effect is the antenna used by every radio receiver, every TV set not connected to a cable system, every satellite dish, and so on. Without it, radio and TV broadcasting would be impossible. --Anonymous, 04:21 UTC, July 21, 2008.
As for why foods taste different, there are many reasons. One is that the air doesn't heat up in a microwave oven like in a regular oven. This means the surface of bread doesn't dry out, for example. That's good if the bread was stale already but not so good if it was soggy. Another diff is that foods often cook for different lengths of time. Longer times allow flavors to blend more. StuRat (talk) 03:31, 21 July 2008 (UTC)[reply]
There are some interesting experiments with microwave ovens which I have seen on You Tube that take advantage of the fact that when a match is lit and covered with a glass inside a microwave the burning gases act like a conductor. Placed in a microwave oven the microwaves then react with burning gasses to form a plasma in a very spectacular fashion. -- adaptron (talk) 07:28, 21 July 2008 (UTC)[reply]
One of the reasons why food tastes different is the lack of 'browning' - microwave ovens use a lot of quite low energy waves - (lower energy than that given off by a heat lamp) - but uses massive ammounts of them - it's a bit like cooking with massive amounts of tepid water (very poor analogy) - because the energy is low it does not cause burning/browning - a bit like steam cooking.
Does any article describe or point to a reference of an experiment in which a large diameter axial fan was setup in the vertical and turned at high speed for the purpose of generating a vortex to serve as a typhoon or a hurricane "seed"? -- adaptron (talk) 07:21, 21 July 2008 (UTC)[reply]
Well, a hurricane is out of the question. Their spin is a consequence of the Coriolis effect, not a requirement for formation -- much less issues of scale. A vertical fan is also the wrong method of formation for a tornado, which originate from horizontally-inclined mesocyclones. Of course, the incorrectness of the approach doesn't preclude somebody from conducting an experiment anyway. 199.209.144.218 (talk) 12:43, 21 July 2008 (UTC)[reply]
Skin Bleaching
Started to read a new trend of anal bleaching but was not able to locate any legitimate medical articles on the procedure and the safety of this. Does anyone have any info or links for me? I don't know exactly what chemicals are used or any long term effects of this? .....you can start laughing now..... --JennaHunter (talk) 13:15, 21 July 2008 (UTC)[reply]
I would certainly expect it to be painful and result in swelling. I'd expect that fasting before the procedure might be in order to reduce the...err..."use" of the area following the procedure. Perhaps only bleaching a bit at a time might be safer, but whole area bleaching is probably done, too. StuRat (talk) 13:37, 21 July 2008 (UTC)[reply]
Depends on the context. If your talking about a global-view, then anything anything above the contentnal shelf... ~300feet. If your talking about a local ecological view then either (1.) anything above the thermocline (~30-50 feet) or (2.) anything in the zone where sun-light is a major factor (~150feet). Of inteses might be: Intertidal zone, Littoral zone and surf zone. 63.80.111.2 (talk) 17:30, 21 July 2008 (UTC)[reply]
Stability of bikes with different wheel-sizes
My father and one of his oldest friends have been debating an issue of physics ever since they where in their early teens. They both got bikes when they were 13 or 14 and they (naturally) started arguing which one was better. My father's bike had bigger wheels, so he argued that it's more stable. Since the wheel is bigger, the gyroscopic effect of the spinning should be bigger, my father thought. His friend, as young boys are want to do, passionately disagreed. He argued that if the bikes are travelling at the same speed, his wheels will spin faster, thus eliminating any advantage my fathers bike might have had. it's now 35 years later, and the issue still haven't been settled.
He asked me, and I told him only the very basic stuff I know, that the gyroscopic effect depends on the angular momentum of the wheel, which does increase with the size of the wheel. However, I haven't studied physics for years and years, and I can't even come close to figuring out whether the faster rotation of the smaller wheel will be enough to outweigh the longer radius of the larger wheel. I suspect this comes down to an issue of mass, since the larger wheel presumably have more mass, it will win out. But what if the two wheel had the same mass (the smaller one is denser, or something)?
I'd say the larger wheeled bike would have a greater rotational inertia, since that's related to the square of the radius, not just the radius. That, in turn should provide more gyroscopic effect. However, I disagree that the gyroscopic effect is all good. While it helps maintain stability while going straight, this also makes turns more difficult, requiring you to slow down more to turn. StuRat (talk) 16:57, 21 July 2008 (UTC)[reply]
POPCORN EFFECTS ON INDIVIDUALS WITH TYPE 2 DIABETES, INSULIN DEPENDENT?
I'd say plain, air-popped popcorn with no toppings is an OK choice, based on the glycemic load of only 3 units per cup: [15] (out of around 100 units per day as a general recommendation, likely less for diabetics). Also, it's difficult to consume calories very quickly with such popcorn, so what little insulin production a person retains might be able to handle this slow pace. However, since a cup of popcorn only weighs 8 grams, it's easy to eat a dozen cups without even thinking about it. Such quantities would be bad. If this isn't just a general knowledge request, but pertains to a particular individual, I'd strongly suggest talking with a doctor or nutritionist recommended by the doctor. StuRat (talk) 17:15, 21 July 2008 (UTC)[reply]
Concur with StuRat, and, just to add something to this ec, I'll again emphasize plain, air-popped popcorn. Other varieties start loading up stuff that increase health concerns, diabetic or not. — Lomn17:25, 21 July 2008 (UTC)[reply]
Fan blades and turbine blades
Why are fan blades and wind turbine blades generally very different shapes? Fan blades (such as from a desk fan) are frequently much larger and more "dish" shaped that turbine blades, which are usually thinner and more wing-like.
I would have thought that if both designs were aimed at maximizing efficiency, where efficiency is either most wind per Watt or most Watts per wind, that the two blades would look quite similar. No? — Sam 17:20, 21 July 2008 (UTC)
![[14]](https://en.wikipedia.org/wiki/Image:Carboxylic_acid_dimers.png){kind=link}
