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.
If I take a mole of some element, measure its volume, then divide by 6.024 * 10^23, and then find the radius of the sphere with that volume, what am I measuring? Van der waals radius? —Preceding unsigned comment added by Em3ryguy (talk • contribs) 01:16, 4 July 2009 (UTC)[reply]
I'm not sure you are measuring anything useful. Any substance is going to have a space between its atoms in any phase of matter; your calculation includes this extra-atomic space as part of the radius of the atom itself. Even assuming you had a perfect crystal at absolute zero (which is an impossible to reach state), you still have to consider packing efficiency. In any real solid, the atoms are going to still obey kinetic molecular theory in that they will vibrate in place; and this motion will also add volume to the theoretical perfect packing required for your calculation to work. See Van der Waals radius#Methods of determination for real experiments used to calculate the Van der Waals radius. I am pretty certain that most modern chemists would use X-ray crystallography to find such values today. Also, the Van der Waals radius is something of a meaningless curiosity. It supposes that atoms are hard spheres; they are not, and do not behave as such under any conditions where their radius is likely to be important. --Jayron32.talk.contribs01:28, 4 July 2009 (UTC)[reply]
Useful or not, though, there is a technical term for this radius: mean interatomic spacing, or crystal lattice atomic spacing (depending on the type of matter, you might or might not have a crystal lattice). Take a look at this material science textbook, for example. Nimur (talk) 04:00, 4 July 2009 (UTC)[reply]
The real reason the most shell fish should be kept live until cooking
I'd like to read a accurate and somewhat scientific description of the reason that most shellfish are kept alive until cooking. I haven't been able to find much on or off Wikipedia. ike9898 (talk) 01:26, 4 July 2009 (UTC)[reply]
No, it's a good question from the OP because other dead animals we eat aren't kept alive until throwing them into the cooking pot. Tempshill (talk) 04:27, 4 July 2009 (UTC)[reply]
Shellfish are kept alive until cooking because there is often no way to distinguish between a recently dead shellfish and a long-dead shellfish. This is especially true of true shellfish like clams and oysters; you generally only can tell if its good to eat if it hasn't rotted, and the only way to tell if it hasn't rotted is to ensure its still alive when you cook it. Most live shellfish ship pretty well on ice, which is why you can get live clams pretty much anywhere (for the right price). Heck, I've seen them in seafood markets in Chicago, which is 1000 miles from an ocean. Crustaceans, which often get classed as shellfish, (though they really aren't), like shrimp, prawn, lobster, and crab are probably safe to eat if frozen alive; in fact lots of shrimp is handled that way. Lobster, on the other hand, is not generally cheaper to ship frozen than alive; unlike shrimp, lobster can survive for a long time out of water, and can survive in a "dormant" state if kept on ice, like dry ice, which is why live lobsters can be shipped to many parts of the country. Crabs are usually cooked and packaged on the boat, in the case of snow crabs or king crabs, which are the kinds of crab you get when you get those crab legs on the chinese buffet. Other types of crab, such as dungeness crab or blue crab are usually only availible dockside. Live crabs are cooked to consume at the restaurant, or cooked and picked and shipped in the form of "lump crabmeat". Unless you are at the shore, you are not going to be able to get raw or fresh crab to cook. --Jayron32.talk.contribs18:13, 4 July 2009 (UTC)[reply]
Original poster here I'm afraid everyone who's answered so far doesn't know much more than I do, and I really think that there is more to it than what has been mentioned so far. I have seen some (unreliable) sources explain that it has something to do with autolytic enzymes that are released when the animal dies which break down the tissue rapidly. I also think I've heard about some serious food safety concerns. Anybody else have input? ike9898 (talk) 01:13, 5 July 2009 (UTC)[reply]
I think Shantavira, Edison and Jayron32 have a bit of a point. In particular, most seafood including fish generally has to be fresh and is usually cooked within a day or two of cathing or frozen or otherwise prepared. You do get live fish in restaurants, but for home use, carrying and storing live fish is impractical but live shellfish is usually not. Shellfish may be somewhat worse then fish (I see suggestions they should be cooked within a few hours) so this may not entirely answer the question but I think it's getting there. The fresh is best mantra is of course a common view, and it's not uncommon for there to be live chickens in wet markets but I'm not entirely sure if many people would actually want to eat a beef from a cow slaughtered a few hours ago. Nil Einne (talk) 12:42, 5 July 2009 (UTC)[reply]
I don't think your statement about live crabs is entirely accurate. It depends where you live. It's not that hard to buy live crabs in Kuala Lumpur or other areas of the Klang Valley for example which is not that close to the shore [1]. This is probably true in most largish Malaysian cities even ones that are further from the shore (although given its geography, most Malaysian cities aren't that far from the shore). I tried to find evidence for live crabs from Ipoh which is probably further from the shore but couldn't find definite evidence other then from restaurants. It's probably not as easy nowadays as it was in the past given the changing demands, the growth of supermarkets and hypermarkets and the lower popularity of wet markets but I still think it's likely not that hard. And as mentioned in the thread, they may be available in supermarkets and hypermarkets in Malaysia, like Carrefour sometimes. I suspect this is the same in many parts of South East Asia and even more so in East Asia. E.g. this [2] is supposedly in Walmart in China although which Walmart isn't specified... In other words, it depends a lot on the local preference, market and demand. N.B. live fish are quite common in most Malaysian restaurants including cheap coffee shop ones. Nil Einne (talk) 12:28, 5 July 2009 (UTC)[reply]
@Jayron ... frozen alive; in fact lots of shrimp is handled that way ... Don't know about your shriping boats, but most of the ones I've seen tossed them into boiling water before they got frozen/ stored on ice.71.236.26.74 (talk) 14:31, 5 July 2009 (UTC)[reply]
Many are, but many are not. Because of their fiddly size, ease of spoil, and relative expense, shrimps are processed right on the boat and the processing may be in a number of ways. Besides size sorting, the shrimp may be cooked or not, de-"vein"ed or not, have the tail removed or not, and have the head removed or not. The stuff you find at the local mega-mart is most likely to be cooked because most people aren't interested in doing that part themselves, but the product shipped to restaurants would more likely be in the raw state. Matt Deres (talk) 23:33, 5 July 2009 (UTC)[reply]
It happened to me at one era in my life right after breakfast, otherwise not for many years. It was as automatic as putting a coin in a gumball machine. Edison (talk) 03:38, 4 July 2009 (UTC)[reply]
Is enquiring about trends in normal bodily functions seeking a medical dignosis? Do most people dump shortly after a meal? Thats all I want to know. Its not medical its statistical. —Preceding unsigned comment added by 79.75.91.172 (talk) 09:57, 4 July 2009 (UTC)[reply]
Seeking a medical diagnosis for a perfectly normal and widespread phenomenon? Have you looked at Gastrocolic reflex it should answer your question and confirm the normality of the action. It happens to a lot of people, particularly after the first meal of the day. Richard Avery (talk) 10:01, 4 July 2009 (UTC)[reply]
From Wikipedia, the free encyclopedia, quote: "The X-ray background is occulted by the dark side of the Moon." Is this true? How could it be? Please explain. And, please do make sure, when you replying, you actually do understand that "dark side of the Moon" do not actually refer to the "far side of the Moon". Another quotation: "The far side [of the Moon] should not be confused with the "dark side" (the hemisphere that is not illuminated by the Sun at a given point in time), as the two are the same only during a full moon. ". Vitall (talk) 03:14, 4 July 2009 (UTC)[reply]
Welcome to the Wikipedia Reference Desk. Your question appears to be a homework question. I apologize if this is a misinterpretation, but it is our aim here not to do people's homework for them, but to merely aid them in doing it themselves. Letting someone else do your homework does not help you learn nearly as much as doing it yourself. Please attempt to solve the problem or answer the question yourself first. If you need help with a specific part of your homework, feel free to tell us where you are stuck and ask for help. If you need help grasping the concept of a problem, by all means let us know. —Preceding unsigned comment added by SteveBaker (talk • contribs)
What lead you to believe that question asking if Wikipedia article statement is true/correct could be homework question??? And, that is unrelated, but where in the world topic of X-ray background radiation are taught in schools? Vitall (talk) 03:58, 4 July 2009 (UTC)[reply]
An edit earlier today changed the link in the article so that it pointed to Far side of the moon, which created an incorrect statement. I've reverted that edit. For an explanation of how the dark (unlit) side of the moon appears to occult the background radiation, see the description for File:Moon in x-rays.gif. Actually, the entire Moon occults the x-ray background, but in that image x-rays generated by the sun are reflected from the lit portion of the Moon's surface. 152.16.59.190 (talk) 03:37, 4 July 2009 (UTC)[reply]
the entire Moon occults the x-ray background <--- I fully agree with THAT statement. Sort of obvious. So do Sun, Mercury, Venus etc. occults the x-ray background radiation. And, so there is absolutely no need to keep designated Moon statement in X-ray astronomy and X-ray background articles??? And no need to emphasize dark side of the Moon? Vitall (talk) 04:08, 4 July 2009 (UTC)[reply]
That was also part of the question. When I was reading X-ray astronomy, I came across statement that "observed X-ray background is occulted by the dark side of the Moon." It sort of throw me away - in what sense? "Occulted" just like "covered", "hid"? Or Wikipedia meant something different? And why only dark side? And if that radiation is observed, how could it be "occulted", etc. Vitall (talk) 04:46, 4 July 2009 (UTC)[reply]
"Occult" means hidden. Astronomers use the term "occlusion" to denote the covering, or hiding, of one phenomenon by another. So to say that the moon occults the X-ray background is technically correct, although it differs from popular usage of the term. Maybe a better term to use in this case would be "occluded" rather than "occulted".--TammyMoet (talk) 08:44, 4 July 2009 (UTC)[reply]
OCCULT verb: become concealed or hidden from view or have its light extinguished, cause an eclipse of (a celestial body) by intervention[3]. Etymology: From 1533, "secret, not divulged," from Latin occultus "hidden, concealed, secret," past participle of occulere "cover over, conceal," from ob "over" + a verb related to celare "to hide," from Proto-Indo-European base *kel- (see cell). Meaning "not apprehended by the mind, beyond the range of understanding" is from 1545. The association with the supernatural sciences (magic, alchemy, astrology, etc.) dates from 1633[4]a century later. Cuddlyable3 (talk) 15:03, 4 July 2009 (UTC)[reply]
Spoiled food is not only unhealthy because of the presence of bacteria or other microorganisms. These organisms have chemically changed the food (e.g. by breaking down proteins; consuming starches and sugars; potentially producing waste toxins, etc.). Nimur (talk) 04:08, 4 July 2009 (UTC)[reply]
Some bacteria and fungi produce toxins as a byproduct of metabolism Even if you kill the pathogen later by cooking, the toxin is still there. See botulism as an example. Our article on Foodborne illness describes this quite well. For your second question, remember the fungi are as different from each other as plants are. Some are beneficial, some are innocous, and some are deadly. -Arch dude (talk) 12:24, 4 July 2009 (UTC)[reply]
Mushrooms are fungi and classified as vegetables, but that doesn't make all mushrooms edible, either. Many species are extremely toxic or psychoactive. There are some fungi that are not mushrooms but still edible, for example the Judas' ear or snow fungus, but I'm not sure what food group they would belong in. ~AH1(TCU)23:53, 4 July 2009 (UTC)[reply]
To expand on Axl and the U.S. government; fruits and vegetables are not culinarily exclusive categories; there is some overlap. Botanically speaking, a fruit is any seed-bearing body in a plant. Culinarily speaking, a vegetable is any part of a plant which is used in cooking for savory applications. Thus, there are lots of fruits which are used as vegetables. Consider not only tomatos, but also the entire family of squash and eggplants and cucumber and lots of other fruits which are used in savory cooking applications. There are even a few plants which, while techinically not "fruit", take on fruit-like applications in cooking, such as rhubarb. --Jayron32.talk.contribs12:40, 4 July 2009 (UTC)[reply]
Well, except that chefs and taxonomists don't necessarily consult each other when working these things out. From a culinary point of view, something you eat is either a "Plant" or an "Animal". That's it. That Linnean taxonomy has changed over the past 100 years to remove fungi from the "plant" kingdom where they were formerly classified, and moved them to their own kingdom on co-equal footing with plants doesn't matter much to cooks. They still use mushrooms in the same manner in cooking as they always have. And they are used as vegetables. --Jayron32.talk.contribs19:22, 4 July 2009 (UTC)[reply]
All these words are informal. Biologically, mushrooms are not even plants -- they are thought to be more closely related to animals, in fact. Looie496 (talk) 18:37, 4 July 2009 (UTC)[reply]
To answer Lowellian: Since humans can survive on a diet that contains very little if any plants (as e.g. in the original life style of Inuit or Mongols), I don't think adding mushrooms will hurt. Fruit and vegetables are a very good and convenient source for many nutrients, but not the only one. --Stephan Schulz (talk) 19:02, 4 July 2009 (UTC)[reply]
Hmmm. This depends on the role fruit and vegetables play in the diet. If you follow modern recommended dietary standards (as in the food pyramid) and replace all fruit and vegetables with mushrooms, then I suspect you will miss some essential nutrients. But I also suspect the same is true if you replace everything with spinach... --Stephan Schulz (talk) 07:24, 5 July 2009 (UTC)[reply]
Not quite true, it would just involve quite a bit of food chemistry. In the days before the internet there was a study (NASA?) that said humans could live on vats of fungi and algae if an adequate number of varieties were selected and chemical reformulation was employed to produce those chemicals that could not be harvested directly. 71.236.26.74 (talk) 08:23, 5 July 2009 (UTC)[reply]
I think it's questionable if you really need milk or meat if you have a well chosen diet. Also bread and other grain/s /products, while not usually considered vegetables or fruits, do come from plant sources. And some fungi are more suitable meat substitutes (being high in mycoprotein) then fruit/vegetable. E.g. Quorn is made primarily from fungi and some single cell protein proposals are primarily fungi Nil Einne (talk) 21:18, 5 July 2009 (UTC)[reply]
Viewing solar eclipse
With a solar eclipse coming on the 22nd of this month I wanted to ask what precautions I must take while viewing the eclipse (i.e. wear sunglasses etc.). And will it be visible here in Pakistan? Thanks. —Preceding unsigned comment added by 116.71.61.65 (talk) 06:06, 4 July 2009 (UTC)[reply]
See same question (Archives June 26 "Solar eclipse") > no. 14 welder's glass/goggles are safe and should be available in Pakistan. Don't use any lower grade though. 71.236.26.74 (talk) 15:26, 4 July 2009 (UTC)[reply]
This map shows the local circumstances of the eclipse; you can click on your location to view these. The total part of the eclipse will not be visible in Pakistan, but the partial phases can be seen close to sunrise in the early morning. The "magnitude" tells you how much of the sun is being covered (multiply the number by 100 for the percentage). ~AH1(TCU)23:38, 4 July 2009 (UTC)[reply]
Physics questions
My science textbook sucks, and I have some questions about motion (Note: please don't oversimplify anything):
When I lift an object, I'm converting some form of energy inside me into kinetic energy (to lift the object) and then to gravitational potential energy. When I drop the object, the energy is converted back into kinetic energy. Once the object hits the ground, where has the energy gone? There's no kinetic energy.
My textbook states "... when he [a weightlifter] holds the barbell above his head, no work is being done on the barbell. The weightlifter is applying an upward force equal to the weight of the barbell, but there is no movement in the direction of the upward force." This doesn't sound right - surely work is being done to counteract gravity and prevent the barbell from falling?
If I hit a very small brick with a very large force (sideways, so the brick may move), my hand will hurt because of Newton's 3rd law. If I hit a brick wall (made of the same material) with the same force, will my hand hurt the same amount?
states that objects at rest have energy. The Energy article states that energy is "the amount of work that can be performed by a force", but the energy of an object at rest can't be used by any force, can it?
A1. The answer is that when you drop the object down, either it bounces back up again if its something like a ball, or it makes a big sound. It scatters all the air and dust particles in the area and slightly heats up the ground. The energy is dissipated in doing all these small small tings.
A2. Somebody owes Steve a dollar. Well, you're confusing force with energy. The weightlifter needs to keep supplying force in order to counter gravity, but he does no work, and ideally, spends no energy, keeping it up. Work is force times displacement. Since he just has to hold the weight in place, he doesn't do any work.
Give the poor sweating weightlifter a rest and replace him with a six-foot-tall rack to hold the barbell. Does the rack doo work? No. -Arch dude (talk) 12:12, 4 July 2009 (UTC)[reply]
A3. Yes, your hand will hurt the same amount. The thing is, it is easy for us to give more force to a stationary brick wall than a movable brick, because it just, well, moves away. However, for equal impulsive forces, you will hurt the same.
The physics of injury is complicated, so we cannot give a real-world answer. But a simplified answer is that hitting the wall will hurt more, because the "hurt" depends on how much ofhe energy of teh blow is absorbed by the hand. when the brick can move, much of he energey is converted into kinetic energy in the brick, while the rest is absorbed as pressure waves in the hand and the brik, withthe pressure waves eventually dissipating as heat. With the wall, none of he energy is converted to kinetic energy, so more of it is availble to hurt your hand. -Arch dude (talk) 12:12, 4 July 2009 (UTC)[reply]
A4. Read Nuclear Energy. That is the very same energy which can be used to blow up a city.
E=MC2 operates when mass is converted to energy, typically in a nuclear reaction. This is separate from any kinetic energy or gravitational potential energy. However, there is no feasible way to convert ordinary mass conpletely into energy. We know how to convert a tiny percentage of some kinds of mass into energy, as in a nuclear reactor or a thermonuclear detonation. -Arch dude (talk) 12:12, 4 July 2009 (UTC)[reply]
"there is no feasible way to convert ordinary mass completely into energy"... what about matter-antimatter collisions? It's feasible (though fortunately not easy, given the relative lack of abundance of antimatter). --98.217.14.211 (talk) 13:03, 4 July 2009 (UTC)[reply]
Thanks for the answers. I'm still confused about No. 2. Doesn't the weightlifter use energy to exert a force? After all, if I push against a wall I'm using energy to exert a force against the wall even though it's not moving... Where does that energy go? --wj32t/c08:48, 4 July 2009 (UTC)[reply]
Exerting a stationary force does not use energy, and a stationary force does no work. The barbell could be supported at the same height on a pillar or by hanging it from the roof - no energy is used by the pillar or the cable. You could lean a heavy object against the wall - again, stationary force, no work done on the wall, no energy being used. Your body uses energy all the time, to keep your heart beating, your lungs breathing and to keep you warm. Sometimes some of this energy might do external work - when you are lifting a weight, or pushing a moving object, for example. But all the energy used by the stationary weightlifter or the stationary wall pusher is wasted as heat - none of it does external work.
For extra credits, analyse the energy and work in a frame of reference in which the weightlifter or wallpusher are not stationary - put the weightlifter in a lift moving vertically at constant speed, and put the wall and wallpusher on a train travelling on a straight track at a constant speed. Gandalf61 (talk) 09:07, 4 July 2009 (UTC)[reply]
Just to add to what Gandalf said, when a weightlifter holds a dumbbell in the air, he is not doing work in the scientific sense of the term. It may look as if he is, with all the sweating and gurning, but muscular effort is not the same as work. Muscles are designed to be most efficient for running and throwing, and other dynamic activities. Under those conditions, the force they exert is cyclic, so they get a chance to recover between contractions. They are not designed for exerting large forces over long periods of time. From what I can gather from a quick look at muscular contraction, a muscle fibre contracts when it receives a command, and then starts to relax whether you want it to or not. The biochemistry of muscle fibres means that they cannot stay contracted indefinitely. If you tell a muscle to exert a constant force, what actually happens is your nervous system triggers one bunch of muscle fibres; and then, when they get tired, it triggers another bunch. Eventually it runs out of fresh fibres and has to start re-using the first bunch again. This is why muscles twitch under these conditions. The muscle is thus consuming chemical energy all the time just to stay in one place. --Heron (talk) 10:13, 4 July 2009 (UTC)[reply]
I disagree with Rkr1991's answer to question three. Try punching a punching bag as hard as you can. Your hand might sting a little. Now try punching a brick wall as hard as you can. [Medical advice: don't actually try that.] In both cases, the change in momentum (impulse) is the same. The movement of the punching bag allows the impulse to be applied over a longer period of time, which means that the maximum force applied is lower. It's the maximum force that determines the pain (and severity of injury). In your scenario where the small brick moves, the impulse is applied over a longer time period. Axl¤[Talk]11:32, 4 July 2009 (UTC)[reply]
By impulsive force, I mean a large force applied over a very short period of time. Punching the punching bag increases the time of application of force, because it deforms, or as I said, moves away. So, it doesn't hurt as much. I stand by my statement. Rkr1991 (talk) 12:42, 4 July 2009 (UTC)[reply]
We may never be able to exert the ideal impulsive force, but the closer we get to it, the more it hurts is my point. A shorter sharper strike is more painful on the hand than a longer drawn out strike. Rkr1991 (talk) 04:51, 5 July 2009 (UTC)[reply]
If you are given only the color of parasols, which is more likely to keep you cooler, black or white one? I think black color absorb more light (at least in the range of visible frequency), so it tends to keep you less cool than white one.
Like sushi (talk) 07:53, 4 July 2009 (UTC)[reply]
No, this is wrong. Visible light will indeed warm you unless you are a perfect mirror. Where else would the energy go? Or why would a monochromatic laser in the visible be able to burn holes through some material (including "you" ;-)? --Stephan Schulz (talk) 11:38, 4 July 2009 (UTC)[reply]
The human body preferentially absorbs infra red. It penetrates to a couple of inches into the body. Other wavelengths do not penetrate and therefore are not absorbed. —Preceding unsigned comment added by 79.75.115.133 (talk) 22:37, 4 July 2009 (UTC)[reply]
It's correct that infrared is absorbed quite well. But it is not correct that other wavelength "do not penetrate" and therefore "are not absorbed". Hold a strongish flashlight up against your hand in the dark to see visible light partially penetrating through a part of your body. And even if a given wavelength is only absorbed on the surface, it will still heat the body. Light does not penetrate most metals (due to the electrons ability to interact with nearly all photons), but an iron skillet in the sun will still heat up. --Stephan Schulz (talk) 23:09, 4 July 2009 (UTC)[reply]
As far as I understand it, light colours reflect more light and tend to keep you cooler if you are wearing them? The opacity of the material may also be a factor. Exxolon (talk) 12:23, 4 July 2009 (UTC)[reply]
Would a two-tone parasol that is white (or even better: aluminised shiny) on the top and black on the inside surface keep one coolest? It could be made reversible for use as a warming umbrella in Winter. Cuddlyable3 (talk) 14:30, 4 July 2009 (UTC)[reply]
This general question came up some time ago, in the guise of whether light or dark clothing keeps you cooler. As I recall, there were arguments in both directions, and it was never really solidly resolved. Looie496 (talk) 16:44, 4 July 2009 (UTC)[reply]
I think black on the bottom has pros and cons. On the one hand radiation reflecting up against the bottom won't reflect back down and hit you, but it's not as if that energy just disappears. The parasol will convert it to heat, some of which will reach you anyway by conduction through the air and radiation. Rckrone (talk) 18:05, 4 July 2009 (UTC)[reply]
I asked here some time ago (in fact, on may 20) about the definition of "work", and have come to know that the same amount of force applied for the same time could mean different work done.
I was browsing today's questions and noticed something.
As the work is defined as Force*Displacement, (although I don't know much about what displacement is), it seems that objects exerting some force, but stationary in a reference frame are doing some work for an observer in a diferent reference frame. As any two parts comprising an object are attracted to each other through gravity, and if the object does not change shape, there is a force to cancel out the effect of gravity, and as the object is displaced (right?), objects in an inertial motion seem to do work.
Is it right for objects not changing velocity to be doing work?
It's not possible for objects to exert a force on each other while remaining stationary. If you push against a wall you will accelerate away from it unless you brace yourself against something that's ultimately attached to the wall, like the floor, in which case the sum of the forces against the wall and floor will be zero. There's no net work being done with respect to any reference frame. Objects do self-gravitate and there is a force opposing that, but the sum of the gravitational and opposing forces is zero. -- BenRG (talk) 13:44, 4 July 2009 (UTC)[reply]
(ec) Let us first see what Displacement is. It is a vector, having direction pointing to the direction of the overall motion, and magnitude the length of the shortest line joining the initial and final points. Please read the relevant the relevant article for further clarifications. We need to get one more point clear. Say I push you (literally). The force is applied by me and you move. The product of my force and your displacement is work. So Work done by an object A on another object B is the force applied by A to push B multiplied by the displacement moved by B. I have to say, it should be a dot product, but never mind. it seems that objects exerting some force, but stationary in a reference frame are doing some work for an observer in a different reference frame. Yes, that's right. Work is dependent on reference frame, that is, it depends on how you look at it. As any two parts comprising an object are attracted to each other through gravity, and if the object does not change shape, there is a force to cancel out the effect of gravity, and as the object is displaced (right?), objects in an inertial motion seem to do work. I think you are a little confused. Objects push other objects to do (mechanical) work, not themselves. However, you can say gravity (earth) does work on these objects. Is it right for objects not changing velocity to be doing work? The fact that whether the object that is doing the work is moving or not is irrelevant. What matters is the force applied by the object and the displacement on the object on which work is done. Rkr1991 (talk) 13:50, 4 July 2009 (UTC)[reply]
I should have said "objects doing nothing else than inertial motion" for the last one? And (though I may have been confused) as two parts are both attracted to the other by gravity and counter force is by both for both, both parts are applied force and (as the object as a whole is moving) both parts are displaced. That was my point.
Basically if a moving object isn't accelerating, it must be that the net force on it is zero. So while it's possible for something else to be exerting a force on it in the direction of motion and therefore doing work to it, some other force either from the same source or from somewhere else must be canceling it out and therefore doing the same negative work to it, which is why the kinetic energy of the object stays constant. Rckrone (talk) 19:00, 4 July 2009 (UTC)[reply]
So, it is the net force that matters. Then no work done for objects stationlly in a reference frame should be ascribed to zero net force than to zero displacement in the reference frame, because displacement differs in reference frames.
Like sushi (talk) 01:42, 6 July 2009 (UTC)[reply]
One more thing. Different time lag between two works results in different displacement (not one while the force is applied, but overall displacement) with the same total work, even in the same reference frame. Or can works with a time lag not be added or subtracted directly? If there is no problem with this, I think I need to understand "work" as something that does not reflect total displacement in a reference frame nor force (independently of reference frames) straightly.
Like sushi (talk) 05:23, 6 July 2009 (UTC)[reply]
You're free to talk about the work done by specific forces, but if you want to consider the total work done by object A on object B, then that's going to be the value corresponding to the net force of object A acting on object B. For example in the case of two halves of a moving object exerting gravity on each other, if you wanted to you could say that half A is doing work on half B through gravity, but at the same time A is doing the same negative work on B through the normal force, and so the total work that A is doing to B is zero.
As for the time thing, work is given by W = F.d only in the case of a constant force. If some displacement takes place in the absence of any force, then the work being contributed at that time is zero. For work based on a time dependent force you would need something more like where v is the velocity of the object. Rckrone (talk) 08:22, 6 July 2009 (UTC)[reply]
Thank you for replying. I think I understand that total force and work is zero in the case. But about the time lag, I don't mean not-constant force. I am thinking about two series of works by constant force which are done with a time interval.
I'm not sure, but is mass needed to deteremine the velocity when the work and force are given? I think it is not needed to deteremine the force when the work and velocity are given.
Definitely insect pupae, the question that now remains: pupae of what? Could be some sort of potter wasp or mud dauber. The only way to be sure (or at least have a better id chance) is to take some pupae and put them in a container to allow them to hatch and attempt to id the imagos. We'll await a further post. Richard Avery (talk) 17:40, 4 July 2009 (UTC)[reply]
In a medical article Im working on, I need a term to describe the coining of new syndromes... This has to do with Rumination syndrome, where a recent paper proposes the characteristics, diagnosis criteria, causes, and potential outcomes of the disorder in adults (Where the syndrome until now was considered a disorder of infancy).
Is there a term to describe this process of formally and medically assigning the symptoms and causes of a disorder/disease? -- ʄɭoʏɗiaɲτ¢17:47, 4 July 2009 (UTC)[reply]
I am reading a science fiction book and the "antagonist" is a "rogue pulsar." In the story, there is a rogue pulsar travelling through a solar system and it threatens to destroy a planet and it's civilization on its way by. Is this possible? Can pulsars travel through space? —Preceding unsigned comment added by 216.154.19.192 (talk) 19:07, 4 July 2009 (UTC)[reply]
Well, pulsars are just rotating neutron stars, and should have a similar distribution of position and velocity as their progenitor stars. That means that yes, they travel through space and might come close to other stars and solar systems. But they are not traveling in some kind of controlled manner, and the chances of an encounter with any given star systems are miniscule. Also see this article. What is the title of the book in question? --Stephan Schulz (talk) 19:18, 4 July 2009 (UTC)[reply]
You might consider checking out the book Death from the Skies, which has a chapter dealing with how a black hole might destroy the Earth. A rogue neutron star (of which a pulsar is a subtype) would behave quite similarly to a stellar-mass black hole, so it should be a good approximation. Additionally, pulsars generating X-rays or gamma rays could damage a planet from farther away -- in this case, disruption of the Earth's ozone layer is the primary mechanism. To directly answer the question, though, yes, stars move relative to one another. Most roughly orbit a galaxy in the same direction, but some could orbit in retrograde (likely as a result of a previous close encounter with another star) and a galactic collision would greatly raise the odds of a stellar encounter -- though the odds remain extremely low. Proper motion is the measure of a star's motion relative to the Sun. Barnard's star, for example, will move two light years closer to the Sun over the next ten thousand years. — Lomn03:37, 5 July 2009 (UTC)[reply]
Yes, the book I referenced is, indeed, Star Trek: Mere Anarchy. Thanks everyone. With science fiction, one can never tell just how accurate things are. I'm still trying to get my transporter to work properly . . . —Preceding unsigned comment added by 216.154.19.192 (talk) 04:32, 5 July 2009 (UTC)[reply]
A similar event is in the (deep) backstory of Greg Egan's recent novel Incandescence – which is set in the galactic core, where stars are closer together and thus near encounters are more frequent than around here. —Tamfang (talk) 18:56, 21 July 2009 (UTC)[reply]
Is there a term for this psychological phenomenon?:
Let's say you're feeling angry or depressed about something which you know, rationally, is petty, selfish, insignificant, and just not worth that kind of emotional reaction(like a comment on the Internet denouncing your favorite books, or being denied a small treat you weren't really entitled to). But rather than admit to yourself that you're getting worked up over that, you tell yourself that your negative feelings are actually caused by something else-- perhaps something(like, say, governmental corruption) of greater significance to the world but with less personal import than the aforementioned petty thing. Has this form of self-deception been documented and named? If so, is it common? 69.224.113.202 (talk) 19:08, 4 July 2009 (UTC)[reply]
It seems to me that displacement is concerned with changing the target of your anger (or other negative emotion), while rationalization is changing the supposed reason for the anger. So the OP's query could go either way, depending upon whether he says, "I am not angry at the parking meter that ate my quarter; but at the town mayor for his incompetence" (displacement) or "I am not angry because of the loss of 25 cents, but because it represent governmental incompetence" (rationalization). Of course, ill-feelings are more diffuse than such linguistic analysis, so the distinction in this instance may be somewhat pedantic. May be relevant, though, if one is writing a novel and needs to use the exact term to prevent those &%@$*# reviewers (who never could write anything worthwhile themselves) from nitpicking it apart. :-) Abecedare (talk) 21:03, 4 July 2009 (UTC)[reply]
Also, just a small clarification: what I had in mind is that the real and presumed reasons for negative emotions may be completely unrelated-- as I tried to convey with the examples of (possibly imagined) personal slights and government corruption. 69.224.113.202 (talk) 23:23, 4 July 2009 (UTC)[reply]
A question of comfort
When I leave the shower cubicle for the cooler bathroom, immediately I feel cold across the arms and whole upper body. Though it takes only a few minutes to towel the upper half completely dry, whereupon the discomfort disappears, the way of doing this makes a subjective difference. I find it better to remove all of the water from one part before dealing with another, as opposed to quickly towelling most of the surface water from the whole area then dealing with the residual dampness a part at a time. I know that the water is conducting my body heat to the surrounding air - is this exactly the same as heating the water to evaporate it? In terms of overall heat loss, will it make any difference what towelling procedure is adopted, assuming water is being removed at a constant rate? I'm assuming that any model of the physics involved should ignore body heat generated by towelling effort, including local frictional heating.≥86.146.175.89 (talk) 19:40, 4 July 2009 (UTC)[reply]
Your trunk may tend to be more sensitive than your extremities with regards to heat changes; for good reason. Since all of your vital organs are there, your body would probably react more negatively to even slight temperature changes than would your arms and legs, which while important, from a survival point of view, are more expendable than say your heart or lungs. --Jayron32.talk.contribs19:45, 4 July 2009 (UTC)[reply]
Not sure about the answer but if you wipe yourself down before leaving the shower-cubicle you'll drive off quicker with less wetness for the towel to pick up. A few 'swipes' of your hands down your arms, legs and front (back is a bit tough!) gets rid of a lot of the water and makes it quicker to get dried in my experience. ny156uk (talk)
I'm not sure it matters how much volume of water is on your body so much as how much surface area of your body is wet. In other words a thin film of water after a quick pass may have nearly the same cooling effect as the large drops before any toweling. So being thorough might be the most efficient in terms of losing the least heat. Rckrone (talk) 20:30, 4 July 2009 (UTC)[reply]
Our article on evaporative cooling deals with a device rather than the human body, but the principle described is the same. There are parts of your body that have a lot of sweat glands and there is always some evaporation there so your body's sensors are expecting that. Any excess is perceived as cooling and will thereby trigger a counter reaction e.g. shivering, constriction of small blood vessels and raising of hairs (goose bumps) Water is actually an insulator, so large drops may take longer to cool you than a thin film because some of the evaporative cooling is used to cool the water drops rather than your skin. That's one of the reasons why misting feels cooler the finer the mist is. The other is more surface area. 71.236.26.74 (talk) 01:13, 5 July 2009 (UTC)[reply]
You can't. According to the vacuum energy article, at least, “consensus among particle physicists is that ... vacuum energy cannot be harnessed to do usable work”. Getting “free energy” would violate the law of conservation of energy, which has never been violated in any experiment. Red Act (talk) 01:12, 5 July 2009 (UTC)[reply]
USPTO has granted a bunch of perpetual-motion-machine patents...just one of many pieces of evidence why existence of a patent for something doesn't prove that the something actually works as claimed and that the patent approval process does not include scientific review. DMacks (talk) 05:38, 5 July 2009 (UTC)[reply]
Right. In particular, the "inventors" who were granted the patent linked to do not actually have their device functioning as a net source of energy.[7] It’s all just a pipe dream. Red Act (talk) 06:08, 5 July 2009 (UTC)[reply]
So you can buy a patent on something that could work, saving the cost and effort of actually engineering the device to actually work. When later someone else, unaware of the patent, finds out how to do things and really builds that machine the first one can claim all the benefits and enforce license payments by law? 95.112.189.234 (talk) 12:03, 5 July 2009 (UTC)[reply]
There's some requirement about a patent being "reduced to practice" in order to have a strong claim of originality (and be a valid patent)...you can't patent an idea, but only specific items or processes of it (though they are often be described in vague or general terms). Here's a decent article I found:[8]. On the other hand, Patent trolls do things at least close to what you propose. DMacks (talk) 14:34, 5 July 2009 (UTC)[reply]
The whole Claims section describes the specifics of what is being patented. That appears to be the intended implementation (facts of the process or device) of this ZPE system, not the idea of ZPE extraction in general. DMacks (talk) 16:42, 5 July 2009 (UTC)[reply]
Doesn't mean it actually does what it says it does, just that it's built the way it says it's built. But going back to the heart of the matter in this, "there is some flaw in the patenting process" is a position supported by numerous legal experts (and also why patents are considered self-published rather than reliable proof of anything other than the facts of the device for WP:RS). DMacks (talk) 17:40, 5 July 2009 (UTC)[reply]
So it just building up a legal insecurity for those doing similar work, if they can be sued for doing that work? Patents regarded as being self-published is one thing, but evoking government authority to protect "self-published" things against other people is another thing. Thus owing a government-granted patent at least means that no one doing work on that subject can be sure not to get suede and sentenced. 95.112.189.234 (talk) 18:31, 5 July 2009 (UTC)[reply]
I don't agree with patents "just" doing that, but otherwise yes, companies have huge legal research departments that make sure any work they might want to patent does not fall victim to prior art of existing patents. They might urge adjusting the company's product or process to "novel enough" to avoid being covered by them, they would certainly use careful wording in new patents to make things look clearly novel vs existing work (whether they actually are or not is often a court issue) and/or by trying to invalidate prior patents as too vague or over-reaching. See also Submarine patent, another trap for the unwary. DMacks (talk) 19:33, 5 July 2009 (UTC)[reply]
So you agree that current patent laws incite companies to spend lots of money to "huge legal research departments" to find the proper "careful wording in new patents to make things look clearly novel" instead of using that money on proper original research and development. 95.112.189.234 (talk) 20:02, 5 July 2009 (UTC)[reply]
I have to correct me: I should have said "current patent practice" instead of "current patent laws", but for a researcher that boild down to all the same. 95.112.189.234 (talk) 20:06, 5 July 2009 (UTC)[reply]
Don't put words in my mouth or make it seem like you're winning a debate that isn't happening by forcing me into a corner that doesn't exist. I'm not (and I refuse to) take a position here on what's happening, I'm merely stating the current situation. I didn't say "instead of". But if companies don't carefully protect their interests and aren't careful to make their products distinguishable from competitors and/or protectable from them, you can bet some other company will take advantage of it (read "find a way to get their customers") because there's clear benefit to doing that. DMacks (talk) 02:25, 6 July 2009 (UTC)[reply]
Well, that ratio is a "rule of thumb" and not an exact requirement. That ratio tends to yield best results for dissolving noble metals (like gold). Take a look at Aqua_Regia#Chemistry for the chemical equilibrium equations. To some extent, any answer will boil down to "because that is the ratio which best dissolves gold, as verified by experiment" - but you can get more specific about the detailed physics and ionic chemistry to explain this statement further. Nimur (talk) 01:34, 5 July 2009 (UTC)[reply]
Aqua Regia was discovered by Abu Musa Jabir ibn Hayyan (known in Europe as Geber) some time before 815 AD, or about 900 years before the rise of the modern atomic theory of chemistry. After first inventing both hydrocloric acid and nitric acid, he then determined the best ratio experimentally. -Arch dude (talk) 11:35, 5 July 2009 (UTC)[reply]
The actual molar ratio between Cl- and NO3- is ~2:1 , this fits ok with the ratio required for dissolving gold which is between 4:3 and 4:1 depending on the extent to which NO2 produced produces more HNO3, I've also heard it said that the ratio is a good one for producing NOCl see Aqua_Regia#Decomposition_of_aqua_regia - which is a particularily active reagent - it's suggested that the ratio is the one which dissolves gold most rapidly.
Sauroposeidon
I was reading the artical on the Sauroposeidon and it says that this sauropod is known from four vertebrea. How it is possible to extrapolate an entire animal (length, weight, etc.) from so little data? —Preceding unsigned comment added by 216.154.19.192 (talk) 04:35, 5 July 2009 (UTC)[reply]
Part of it follows the rule of "quacks like a duck, looks like a duck ..." There is a lot more to it, though. Bones grow in response to the stress that they are subjected to in addition to the basic plan laid out in the animals DNA. So the size of a bone will tell you something of the size of the animal. From the shape of the bone you can deduce where in a body it would have been, based on similar bones in other animals. The article states that the ribs were still attached. Our article doesn't say, but in dinosaurs (and some reptiles today) all vertebrae had ribs attached. From the size of those you could also deduce the size of the neck. Blood vessles, nerve channels and tendons leave holes and grooves in bone. From those you can sometimes guess how muscles were attached and thus what an animal looked like and how it moved, based on what is known of similar features in modern animals. There are also bones of related animals where more complete skeletons have been preserved. 71.236.26.74 (talk) 06:14, 5 July 2009 (UTC)[reply]
It boils down to scale: you take a similar sample from an animal you know more about and try to apply the same ratio to get a better understanding of the unknown animal. This works much better in theory than in practise, but it does provide a place to start. In some ways, it's like inferring an unknown person's height when all you have is his shoe size: grossly simplistic, but it may provide useful clues for later. Matt Deres (talk) 16:36, 7 July 2009 (UTC)[reply]
TRYING TO FIND AN ARTICLE ON HOW COME DOES IT SNOW
There is a lot of information about snow in the article titled "Snow". I see several paragraphs about how snowflakes form and fall. DMacks (talk) 07:17, 5 July 2009 (UTC)[reply]
It seems that every time the IPCC comes out with a report they say their previous forecast had underestimated some effect or their model has improved and the effects will be worse. And now I read on the front of New Scientist "It's worse than we thought" about the latest forecasts on sea level rises compared to the 2007 report. Is there any aspect in any of their reports where a later report has said an effect will probably not be as bad as they said previously? Dmcq (talk) 10:01, 5 July 2009 (UTC)[reply]
I don't think that's a correct observation. As far as I can tell, the IPCC position has been fairly stable. The level of detail and the confidence have increased over time (and with that negative consequences can be predicted more exactly), but the basic predictions have not shifted a lot. The 1990 report estimated 3 degrees of temperature increase during the 21st century, the 2007 report has a number of scenarios that still cluster around the same value. Sea level rise from 2001 to 2007 is similar, too (in fact, the nominal 2007 range is lower, but explicitly excludes non-linear changes in polar ice caps). --Stephan Schulz (talk) 10:24, 5 July 2009 (UTC)[reply]
I agree with Stephan Schulz - the predictions have been, very roughly speaking, stable, and I believe there are examples where the prdition has been less significant that in the prior report. It is temping to put together a chart of of the key predictions, but I fear this may run into problems. A small problem is that in some cases the central estimate has gone down, but the range has gone up. A larger problem is that they have modified the way they present some of the values, so there's not precisely an apples to apples comparison. While adjustments for these issues are possible, they constitute research, so they must be done outside WP. Additionally, the reference to the New Scientist statement implicitly accepts its validity - I don't believe everyone or even a consensus is on board with that conclusion.--SPhilbrickT13:25, 5 July 2009 (UTC)[reply]
Sorry yes, reading it better you're right. It is surprisingly consistent despite the improvements in measurements and models. Perhaps I just read too many scare stories that keep pointing out that it could be far worse and quoting the highest figures. And the range of values has got wider instead of narrower because they've put in a number of different scenarios. Dmcq (talk) 16:08, 5 July 2009 (UTC)[reply]
If the cheese is left open it will dry out - a hard cheese can't oxidise in the middle, there might be some oxidisation at the surface - but I don't know what process this is.83.100.250.79 (talk) 13:25, 5 July 2009 (UTC)[reply]
Cheese may oxidize some, but bacterial and yeast action will also work on exposed cheese; if the right mix of cultures are present, you will get a very tasty cheese indeed. These cultures will tend to soften, rather than harden, the cheese. The hard rind is mostly due to drying out. --Jayron32.talk.contribs17:44, 5 July 2009 (UTC)[reply]
If you leave your cheese in the fridge unwrapped, it will dry out. End of story. If you put it in the fridge, you have to wrap it in plastic. If you live in a climate where you can leave it in a cool dark cellar, you can wrap it in cheesecloth and it will be a happy cheese for a considerable time. Looie496 (talk) 01:58, 6 July 2009 (UTC)[reply]
If it is placed in a sealed plastic bag in the refrigerator at 40 degrees Fahrenheit, it should not dry out as you describe, but it may eventually get green mold. If vacuum sealed it may last longer. Edison (talk) 02:20, 7 July 2009 (UTC)[reply]
biology red blood cells
When red blood cells are placed in pure water it bursts,this is due to the absence of which structure.
Since Axl didn't say it, one of our policies is not to answer your homework questions for you. What Axl did - pointing you to how to find the answer - is all we do. Vimescarrot (talk) 14:44, 5 July 2009 (UTC)[reply]
This question has been removed as it may be a request for medical advice. Wikipedia does not give medical advice because there is no guarantee that our advice would be accurate or relate to you and your symptoms. We simply cannot be an alternative to visiting the appropriate health professional, so we implore you to try them instead. If this is not a request for medical advice, please explain what you meant to ask, either here or at the talk page discussion (if a link was provided).
Just a question, as I am ignorant of this subject matter -- is the still pool connected the moving current of the river? Bus stop (talk) 21:06, 5 July 2009 (UTC)[reply]
An "oxbow" would also fit that definition. It is said to be: "An abandoned meander in a river or stream, caused by cutoff. Used to describe the "U" shaped bend in the river or the land within such a bend of a river." Bus stop (talk) 21:37, 5 July 2009 (UTC)[reply]
This glossary is a good find. Seems like "backwater" is the term closest to what I'm looking for—but "backwater", it appears, can be used to refer to something quite vast. I'm looking for a word that can be used figuratively to refer to something off to the side (of the movement and activity of a like substance). I vaguely remember reading or watching something that mentioned still pools connected to a moving body of water—and that they were ecologically important to some species. For example, if you wanted to spear yourself a fish, you might want to find one of these. But it's possible that there isn't a short term for this. —Preceding unsigned comment added by Alfonse Stompanato (talk • contribs) 23:10, 5 July 2009 (UTC)[reply]
Well, Lard suggests that most lard should not melt below temperatures of 30oC (85 or so degrees Fahrenheit). However, lard, like all animal products, will probably spoil if stored for extended periods at room temperature, so storing in a refrigerator is recommended. Intelligentsium22:05, 5 July 2009 (UTC)[reply]
Google books search [9] gives old references suggesting temperatures for long term storage of lard anywhere from 31 to 60 degrees Fahrenheit. Certainly people have stored lard for a time at room temperature, but long term storage seems to require lower temperatures. [10] suggests that antiooxidants can delay lard becoming rancid. [11] Says lard's shelf life is "not particularly long."[12] say that supermarket lard will be usable for one yuear if refrigerated. Lard makes superior pie crusts and biscuits, but the saturated fats are not that healthful. Edison (talk) 22:19, 5 July 2009 (UTC)[reply]
Perhaps - if you could kill every last bacterium and mold spore in the stuff (eg by pasteurization or irradiation) - then you could either can, bottle or vacuum seal it and keep it for a very long time. Whether it would spoil for other reasons (internal chemical reactions, etc) is tough to estimate. But other meat products can be canned (think Spam) and kept pretty much indefinitely at room temperature - those military ration packs are vacuum-sealed and last almost indefinitely - even at quite high temperaturess. I think lard should survive similar treatment. SteveBaker (talk) 23:30, 5 July 2009 (UTC)[reply]
Lard is essentially all saturated fat; as such it is probably atleast as shelf-stable as say vegetable shortening, that is if you aren't going to leave it already opened in your pantry for months at a time, you probably don't need to refrigerate it. It may be animal derived; but its no more a "meat" product than "vegetable oil" is a vegetable. --Jayron32.talk.contribs23:57, 5 July 2009 (UTC)[reply]
OR: We used to store lard in a pot. every couple of days it was boiled in a pot of water and then put in the "larder" (sic.) after the pot no longer felt hot. When the lard had solidified on top of the water it was removed, the water was thrown out and the lard was kept till the next round or until it was used in cooking. This procedure was done as part of the usual cooking routine. So if the stove was run on firewood or coal there was no need for starting it for a separate run. I think there is an old saying out there about having "a pot of lard on the fire". 71.236.26.74 (talk) 03:39, 6 July 2009 (UTC)[reply]
WP:OR Living elderly cooks who used lard to make delectable baked goods say they stored it in the refrigerator. I have seen it turn brown and rancid at room temp in a cabinet. If you make biscuits, piecrust, cookies and such with it every day you could use it up before it turned rancid. Edison (talk) 02:18, 7 July 2009 (UTC)[reply]
Bony lumps
My mind is teasing me; I cannot remember the term for this. There is an inherited condition where there are additional deposits of bone in the mouth cavity. They may be present as bumps in front of the teeth (i.e. within the gum), ridges on the palate, or even processes within the mandible. The condition is not usually a source of trouble; they're just extra bone. I'm drawing a complete blank and my look through our various dental and anatomical articles isn't helping me. I am not, by the way, think of something like tonsilloliths, but of actual additions to the normal bones. Matt Deres (talk) 23:48, 5 July 2009 (UTC)[reply]
Stated that the coal inside a firebox reaches a temperature of 3,500 degrees. This could not possibly be correct. Iron melts way below 3,500 degrees. —Preceding unsigned comment added by 24.189.180.238 (talk) 01:42, 6 July 2009 (UTC)[reply]
I don't know where the source is for that 3,500F figure. But a couple of web pages ([13], [14]) mention firebox temps of 2,500F. Our page on iron gives a melting point of 2,800F. But even if the 3,500 temp is right, that second web page (which give a melting point of iron of 2000F), as well as our page on fireboxes, suggest that melting can be prevented by keeping the firebox covered with cooler water. Makes sense to me, because it reminds me of that camp trick of boiling water in a leaf over a fire. --Allen (talk) 02:07, 6 July 2009 (UTC)[reply]
Wikipedia defines "red hot" (in relation to heat) as follows: "The glowing color of a heated object between about 950 °F and 1500 °F (510 °C to 816 °C}". - GlowWorm. —Preceding unsigned comment added by 98.17.44.60 (talk) 03:16, 6 July 2009 (UTC)[reply]
Coal is a pretty poor conductor of heat, I believe, so it is entirely possible that the coal at the centre is that hot but the coal at the edge, where it is contact with the iron, is below the melting point of iron. Cooling the firebox with water would help maintain that. --Tango (talk) 03:36, 6 July 2009 (UTC)[reply]
Actually, I remember seeing a bit on Modern Marvels or some similar show regarding locomotives that the coal inside a firebox was so hot that the entire thing had to be jacketed in water; this water of course turns to steam and drives the locomotive. However, the show claimed that if the water were allowed to run low, the burning coal could actually melt the iron of the firebox. So the numbers seem realistic. If the iron is constantly being cooled by water, it itself may never reach its melting point even if the coal inside it DOES. --Jayron32.talk.contribs04:36, 6 July 2009 (UTC)[reply]
A locomotive firebox is usually surrounded by water. If the water level in the boiler falls below the top of the firebox, there is a serious danger that the top of the firebox will become too hot, weaken and fail under boiler pressure. A safety device called a fusible plug gives a loud audible warning if there is an insufficient height of water above the top of the firebox. Gandalf61 (talk) 09:24, 6 July 2009 (UTC)[reply]
<following moved from separate post 71.236.26.74 (talk) 15:45, 6 July 2009 (UTC)>
Maximum firebox temperature is 2500 Fahrenheit degrees, according to this reference:
[15] 24.189.180.238 (talk) 15:12, 6 July 2009 (UTC)[reply]
Meanwhile, locomotives can always explode if something goes wrong: read the paragraph of 2-6-6-6 that begins with "One H-8". I don't know the interior workings of steam locomotives, so it might be that this wasn't a firebox issue, but it sounds vaguely familiar. I'd provide pictures if I could, but the only photos of this incident that I've seen were in a printed volume. Nyttend (talk) 04:39, 7 July 2009 (UTC)[reply]
The steam locomotive engineer and fireman (U.S. terms) had a water gauge showing the water level in the boiler. They had to make sure the water level was high enough to prevent an explosion and low enough to allow sufficient room for steam and to prevent water being sent to the drive cylinders. It was manually maintained and not generally automatically regulated. The combustion chamber or firebox was surrounded on the sides and top by the bottom of the boiler, so that water kept the steel at a temperature where it did not soften or melt, and could withstand the steam pressure. This is on the same principle that Michael Faraday demonstrated in lectures that water could be boiled in a paper bag over open flame. The combustion temperature was probably selected to get the most energy transformed from coal to steam power, rather than just sending unburned fuel up the chimney in gas form. A high temperature was needed to get the gases which evolved from partial combustion to burn completely. The boiler also had "staybolts" running between top and bottom to withstand the pressure. If they neglected to inject water from the tank in the tender as water was lost in steam, or if scale clogged the ports on the gauge, or if the cock from the boiler to the gauge were closed and it lied, the water level could drop below the "crown sheet" above the firebox. Then "crown sheet failure" would cause the superheated water in the boiler to burst through the crownsheet, and through the firebox, into the locomotive cab. scalding the engine crew to a horrible death. The ends of the staybolts had holes drilled into the exposed part, so that if a staybolt broke, the steam would whistle through it and warn the crew. Staybolt failyrure could also cause boiler failure. If a tube which carried the hot gasses through the boiler broke, steam would leak out as well. The ends of the tube could be plugged in the shop and the boiler could continue to be used until a general overhaul was possible. A former engineer told me that one reason railroads preferred diesels was the manpower needed for constant inspection of the boiler interior. Edison (talk) 15:22, 8 July 2009 (UTC)[reply]
Doll's rule in evolutionary biology
I want to know what is Doll's rule in Evolutionary Biology.
I am preparing for an Anthropology exam conducted by public service commission of India. The Doll's rule is part of the syllabus for that exam. I did not get proper result when I searched in Google. Please refer the syllabus for the exam in the following link
http://www.threeauthors.com/upsc-exams/show.asp?xx=cse_m&x=9&yy=cse_m
I request you to give me information about Doll's rule
Are you sure you don't mean Dollo's law? Our article is short, but well referenced, and pretty self explanatory. I'll let you read it and decide if that is what you are looking for. It is certainly related to Evolutionary biology... --Jayron32.talk.contribs05:39, 6 July 2009 (UTC)[reply]
How does a bicycle puncture repair kit work?
I would like to know how the components of a bicycle puncture repair kit work. Is sand-papering the area really necessary? I notice the repair plaster things are mostly black (like the inner tube itself) but with an orange layer which is supposed to interface with the rubber solution. Does the rubber solution dissolve this orange layer? Does it dissolve anything else? What's in the orange layer? ----SeansPotato Business07:41, 6 July 2009 (UTC)[reply]
The orange layer does not dissolve. I have often repaired cycle punctures since I was a child. I image that the orange part, which is more flexible than the ruibber part, is to help fix the stiffer rubber part to the inner tube, particularly around the edges. If you did not have the orange part, then the rubber part could more easily start coming away from the inner tube at its edge, but it is held in place by the more flexible orange part. You may notice that the orange part tapers down from the rubber part, so it avoids a step which would otherwise more easily start coming away from the tube. 78.149.198.158 (talk) 11:00, 13 July 2009 (UTC)[reply]
Looking for a theory of a memory
This question fall in the area of psychology: I'm trying to find a name for a theory I have heard. Acoording to the theory (or what I remember of it) we do not - in a way - remember a past event but the last time memorized that event. That is, when memorize something we don't only retrieve a memory, we also "rewrite" it. I'm not sure I found anything on the subject on Wikipedia although confabulation touches the idea. I'd be happy to have any pointers as to what terms I could use to search scientific databases. Samulili (talk) 18:31, 6 July 2009 (UTC) 08:12, 6 July 2009 (UTC)[reply]
I don't know the exact hypothesis (which is the correct name of a scientific "theory", have a look at theory) you describe here, but it certainly touches long-term memory, long-term potentiation and therefore memory consolidation. And my impression is that this hypothesis is oversimplifying a lot, so it probably is no scientific explanation, rather a "layman's terms" explanation. Our memory is more complex than this explanation suggests (for example, there is more than one type of memory). --TheMaster17 (talk) 09:04, 6 July 2009 (UTC)[reply]
I know what you're talking about - the idea is that every time we remember something, the act of remembering it "rewrites" it - possibly with small changes. This is supposed to account for phenomena like False memory syndrome where the act of being repeatedly quizzed about a non-existant event can cause that event to become a memory. Lost in the mall technique is a way to demonstrate that this happens. I think Interference theory comes close to what you're looking for. SteveBaker (talk) 13:59, 6 July 2009 (UTC)[reply]
It's not a Wikipedia article but there was a very interesting story about a study on memory (and similar to the original question,) which I heard on NPR: [here]. The summary is that tests on the effectiveness of Beta Blockers led to research into how well people remember things while taking the drugs and then after they stop taking the drugs. Apparently it was possible to coerce a pre-existing memory OUT of someone's mind while they were on the drug, by causing them to recall a memory and then fail to re-remember it. They would then have no recollection of that memory even after they stopped the drug treatment. --Jmeden2000 (talk) 20:24, 6 July 2009 (UTC)[reply]
Cow identification
What breed are these brown cattle in Cambridgeshire? You pass a lot on the path from the university to Grantchester.
I believe the "bankers" who took over General Motors from Durant were actually the E.I. deDuPont de Nemours Co. When the government ordered DuPont to divest itself of all General Motors stock they had to pass a special law to keep DuPont/General Motors stock owners from having to pay so much tax that they would flood the market of GM stock. —Preceding unsigned comment added by 76.69.149.145 (talk) 10:47, 6 July 2009 (UTC)[reply]
Hello. Is there any simple way to determine the valence of an atom just by looking at its position on the periodic table? If not, which is the simplest way to know the valence of an atom (I'm fed up with having to look up each atom on the Internet :()? Thank you!! —Preceding unsigned comment added by 83.34.232.9 (talk) 11:10, 6 July 2009 (UTC)[reply]
If you mean the number of electrons in the last shell, then the group the element is in is the number of electrons in its valence shell, e.g. Oxygen is in the 6th group and has 6 valence electrons. —Preceding unsigned comment added by 116.71.51.138 (talk) 14:43, 6 July 2009 (UTC)[reply]
That rule of thumb works for many small atoms, but larger more complex atoms have pathological valence behavior. The transition metals are the perfect example of this - almost all of them have two valence electrons, even though they span many columns of the table. Use caution when applying rules of thumb to valence electrons, as the physical behavior can be more subtle. Nimur (talk) 15:00, 6 July 2009 (UTC)[reply]
For main-group elements (The tallest groups, AKA the s- and p- groups, AKA the "A" groups), the ones that start with H, Be, B, C, N, O, F, He; just number those groups (ignore the transition metals for now) from left to right; that is the number of valence electrons in those atoms. Thus, the first tall column from the left has 1 valence electron, the second tall column has 2, the third tall column has 3, and so forth. This only works for the main groups.
For the transition elements, it is a much more complicated situation. Basically, the "d" orbitals are so close in energy to the "s" and "p" orbitals that the atom can freely "borrow" from these d-electrons as needed to expand the number of availible valence electrons. All transition elements at first glance should have exactly 2 valence electrons (since they all have a full s orbital on the outermost energy level, and the "d" electrons are always added to an interior energy level). Take an element like Manganese for example. It has the basic electron configuration or [Ar]4s23d5. So one would say it has a valence of 2 electrons, since there are 2 electrons on energy level 4. However, since the 4s and 3d orbitals are very close in energy, one can find a wide range of valences, and thus oxidation states, for Manganese this is pretty much anything from +1 to +7 inclusive; though the main ones are +2, +4, and +7.
So basically, the system is ONLY reliable for the main group (tall columns) elements, the middle bit is pretty much memorize it or look it up. --Jayron32.talk.contribs19:28, 6 July 2009 (UTC)[reply]
Waste disposal
I was wondering what would happen to an everyday object if it were propelled towards earth from outerspace. It would definitely burn up. Venus has a more dense atmosphere than Earth and a higher surface temperature too so would it not make an ideal place to dump? What would be the problems and disadvantages of doing so? Thanks. —Preceding unsigned comment added by 116.71.51.138 (talk) 14:15, 6 July 2009 (UTC)[reply]
How were you going to get waste to Venus (or anywhere in outer space)? Using a three-thousand-ton rocket, you can loft about fifty tons away from the Earth — and building the rocket and refining its fuel generates more than fifty tons of waste, even if you could recycle all of the components. (For comparision, New York City generates more than ten thousand tons of waste every day.) TenOfAllTrades(talk) 14:33, 6 July 2009 (UTC)[reply]
(EC) Your waste disposal suggestion has a flaw in the "going up" part, rather than "coming down" portion. For rocketsgoing into orbit you'd have to budget $100 million per launch. Attempts to cut those costs by an order of magnitude ended in failure. Since you don't want to have your trash spread over a significant area of real estate or ocean, you'd have to go for a reliable system. NASA budgets about $250,000 per pound going to the Moon and I guess you'd have to multiply that by a significant factor if heading to Venus. You'd also have to transport your trash to suitable launch sites (not in my back yard). There'd also be significant additional waste from producing and discarding the rocket. Since the carbon footprint of moving the stuff into orbit or hauling it toward Venus is unlikely to be lower than that produced by Incineration the idea isn't going to fly :-)71.236.26.74 (talk) 14:44, 6 July 2009 (UTC)[reply]
One thing to keep in mind is that you're trying to solve a problem that really doesn't exist. The whole "we're running out of places to dump waste" meme is a misperception. As I understand it, it started because *some* landfills around heavily populated areas like New York were no longer accepting garbage, but there is more than enough room in rural areas for more landfills. It's a thousand times cheaper to ship garbage from New York to Nebraska than it is to shoot it into space, even when using state-of-the-art nonpolluting landfills. This also ignores the fact that most of the garbage can be re-used, either through recycling the metal/glass/plastic/paper, or by composting the organics, or even just by burning it for energy. (Again, getting rid of it with state-of-the-art low-polluting incinerators is still orders of magnitude less expensive than shooting it into space.) -- 128.104.112.85 (talk) 16:23, 6 July 2009 (UTC)[reply]
Plus following generations might curse you for dumping precious resources in hard to get places. They might have to resort to sorting through our trash for things like copper, gold and titanium (there might be even better examples) because the mining resources are depleted. Even incinerator ashes would be better than going to Venus for resupply. 71.236.26.74 (talk) 17:03, 6 July 2009 (UTC)[reply]
Before the questioner makes a similar argument for supposed "we will never want it" waste, such as nuclear waste, keep in mind that just because we have no use for the waste at this time does not imply that we will never have a use for it in the future. Considering nuclear waste, it may turn out that nuclear waste will become a highly valued resource in the future. It may turn out that it is never used and future generations curse us for creating it. We do not know the future, but we do know that digging up waste on Earth is easier than travelling to another planet to get it. -- kainaw™17:18, 6 July 2009 (UTC)[reply]
Indeed. The most common nuclear waste still contains over 95% of the fissionable atoms. (It becomes waste not because the fissionable atoms are used up, but because of the buildup of fission poisons.) Current nuclear reprocessing methods can bump that from ~5% to ~20% usage, but it is likely that future developments may allow us to increase that even further. Additionally, some of the fission byproducts may have other (non-fission) uses, like in radioisotope thermoelectric generators. -- 128.104.112.85 (talk) 19:20, 7 July 2009 (UTC)[reply]
Supposing that one has some waste to dump in outer space, what is the attraction of using a little planet like Venus when one can drop the waste in the Sun ? Cuddlyable3 (talk) 17:52, 6 July 2009 (UTC)[reply]
It is easier to get to Venus than the Sun. To reach the Sun you have to get rid of all of the angular momentum an object on Earth has due to the Earth's orbital velocity. To get to Venus you only need to get rid of some of it. --Tango (talk) 01:58, 7 July 2009 (UTC)[reply]
The volcano will readily return whatever it is to the surface, in far more diffuse and potentially hazardous form. If the waste can be incinerated, then use an incinerator. If it's something like nuclear waste, you'll irradiate much of the island. — Lomn18:56, 6 July 2009 (UTC)[reply]
The molten rock is moving. So, the uranium must sink faster than the upward flow of the rock. Add to that the fact that the uranium will become molten as well and it is obvious that some of the uranium will be pushed back to the surface - causing a huge radiation problem. -- kainaw™19:11, 6 July 2009 (UTC)[reply]
Uranium melts at 1100 degC - Lava (according to our article) sits between 700 degC and 1200 degC. I would assume that it gets hotter the deeper in the volcano you go. Uranium is about 8 times denser than lava - so it would likely sink to the level where it melts - then mingle with the rock - and ultimately be shot back out of the volcano - perhaps as ash - spreading radioactive debris over a large area. Definitely not a good plan. If it were that easy - trust me - we'd already be doing that! SteveBaker (talk) 01:45, 7 July 2009 (UTC)[reply]
Well, that idea is even sillier. I mean, we can set light to the garbage and burn it without going anywhere near a volcano. The idea only has any merit whatever if you could somehow entomb the waste in the lava and have it somehow wind up never coming back. However, that has no merit either...so forget it! SteveBaker (talk) 03:15, 8 July 2009 (UTC)[reply]
Theoreticly we could transport the waste to Venus;Mars;Moon...on a more cheaper scale, for instance the creation of a giant pipe to space to be loaded on transports made in space so negating the need for the 25 billion tonn rockets people are talking about; if we are talking the future this is feasable but highly improb as the earth moves matching rotation ECT...am sure people would say other reasons. in the future we may be able to process waste in ways where we can gleem all the usfull bits down to molecular level and only the most fundemental parts would be waste. However we could just store waste in space at absolute Zero in giant ice cubes so if the need arrises we can collect thaw and use seems sensible to me and space is so very very large214.13.64.7 (talk) 04:36, 13 July 2009 (UTC)[reply]
Simulate semiconductor
Ok, I'm assuming that there is some software that allows you to simulate flow of e and holes in a semiconductor piece whose doping is specified.
Is there a generic name for such softwares? I want to write one as my project. Should I post this in Physics, computer or maths ref desk. It involves all three.
Putting 'simulation' 'electron hole' etc into a search engine throws up many examples - as for specific software - don't know.
Also see [16] which gives transport physics in semiconductor devices as a possible name for the area - also try searching for "transport models semiconductor devices" - it looks like "hydrodynamic model" is an alternative method to a "monte carlo" based model.83.100.250.79 (talk) 21:49, 6 July 2009 (UTC)[reply]
Have you looked at SPICE ? SPICE is the standard electrical engineering simulation software for semiconductors. The more advanced commercial SPICEs (like HSPICE) simulate device-physics quite thoroughly. You can program down to very specific minutia of the semiconductor geometry, physical properties, thermal effects, etc. Depending on who you ask, SPICE is either a software simulator, or a programming language, or an internal engine for another CAD tool. In its original incarnation, SPICE was 1-part circuit net simulator and 3-parts differential-equation-solver; it has since evolved into a full-fledged circuit design, layout, and simulation engine that is distributed in several free and commercial versions, and integrated into larger CAD packages. Nimur (talk) 23:35, 6 July 2009 (UTC)[reply]
Assuming that, for a dog, a car is a natural object to urinate, is there a special reason why they always do it on the tyres? For us this choice is more or less OK, but what do they mean? Thanks --pma (talk) 17:34, 6 July 2009 (UTC)[reply]
My guess is because the tire is attached to the ground, much as a growing plant (a tree) might be. But I am not sure why a tree, except that marking territory may be involved. Bus stop (talk) 17:45, 6 July 2009 (UTC)[reply]
(ec) :Dogs signal who they are by marking with urine any prominent outcrop on the ground that other dogs may sniff. The tyres of a car are the only parts that touch the ground. Cuddlyable3 (talk) 17:47, 6 July 2009 (UTC)[reply]
Seeing as no dog pheromones have been scientifically described or characterized, and no human pheromones have been scientifically described or characterized, I would suggest the previous answer be taken with a huge dose of skepticism. Rockpocket02:03, 7 July 2009 (UTC)[reply]
Because it's there. I walked a lot of male dogs and they pee/poo anywhere within reach. Tires just happen to be a convenient place. Since tires give off a lot of scents obtained from travel (roadkills, poo and other street smells) they become a magnet to curious dogs. My dogs also sniff my feet to check where I went when I come home from a journey. --Lenticel(talk)05:58, 7 July 2009 (UTC)[reply]
"My guess is because the tire is attached to the ground, much as a growing plant (a tree) might be. But I am not sure why a tree, except that marking territory may be involved." -- Is this also the reason why dogs love to pee on fire hydrants?
76.21.37.87 (talk) 05:40, 8 July 2009 (UTC)[reply]
walking across the USA
What supplies would be best for walking across the USA from Atlantic to Pacific (say Baltimore to Portland Oregon)? Weight should be 50lbs or less, and you would start in April. Assume you do not have shops at which you can resupply. 65.121.141.34 (talk) 18:19, 6 July 2009 (UTC)[reply]
Sorry should have clarified better. This is a survival scenario. So for food, a rifle say is acceptable as there are animals to eat. 65.121.141.34 (talk) 19:06, 6 July 2009 (UTC)[reply]
(before Edit conflict with OP) How do you propose to feed yourself on less than 50 pounds? It is probably going to take 8-9 months to make the trek by foot; it takes people about 3 months to hike the Appalachian trail, and that is probably 1/3rd the distance you are trying to cross. If you are not going to be buying any food along the way, then the best thing I can think to do is to arrange for someone to mail you food and other supplies and pre-designated depots. Packages mailed to a post-office or UPS store in your name can be designated to be held for pick-up. If you carefully plan your route, and have your friends mail you packages to the right places to arrive at the right times, you can keep yourself stocked. Alternately, you can have someone go ahead of you in a car and bury caches containing the supplies which you can dig up; that's often how early explorers did it. But considering that you probably need to eat at least 1-2 pounds or so of food each day, you will probably only be able to carry a month or less of food (considering also that part of your 50 pounds is going to be non-food supplies as well). (after Edit conflict) OH!!! You want to be able to hunt and forage for your own food? That will be significantly harder; probably impossible to do so legally, given the laws in many places about poaching or the like. --Jayron32.talk.contribs19:10, 6 July 2009 (UTC)[reply]
It is also guaranteed to a) reduce any other provisions and your clothing to shreds, since goats will eat/chew anything and everything. b) extend your trip by a couple of years because most goats aren't that cooperative, don't like hiking all day and spend most of their time awake either eating or ruminating during which time only an act of god will move them. Also the US is no longer the Wild West. If you want to go hunting you need a hunting license for each county you are passing through. Fishing licenses are separate in most jurisdictions. Regulations on carrying weapons and ammunition vary widely. The bigger issue than food is going to be water. There are quite a few places where there's absolutely no water to be found for miles around. Then there are places where the water that is there will kill you. Either fast or slowly. Then there's the weather. People who wander away from civilization do get killed due to exposure. In summer you get toasted [17], in winter frozen to an icicle [18]. ...and all that without meeting any of the even less desirable elements (of society). [[19]] 71.236.26.74 (talk) 21:17, 6 July 2009 (UTC)[reply]
It isn't possible. You have close to a thousand miles of desert and mountain to get across, and you won't make it. There's hardly anywhere where you can legally hunt out of a special season. If you carry a gun, you'll be arrested 20 times, and even if not, hunting would slow you down so much that you'd be caught by winter halfway. This just isn't a feasible scenario. Looie496 (talk) 20:49, 6 July 2009 (UTC)[reply]
Actually, in most of the United States, it is technically perfectly legal to carry a firearm unconcealed (legislation varies by state and local jurisdiction - Wikipedia has a great set of articles, Gun law in the United States and Gun laws in the United States (by state) - but these are guides only, and you should check with the local sheriff or consult a lawyer regarding specifics). Rifles and shotguns are less regulated than handguns in most states. However, even if it is legal to walk along the road carrying a hunting rifle, it will almost certainly draw attention from law enforcement, who may question you (and may have the option to arrest you, depending on local laws). (They will probably also inform the law enforcement in the next district you plan to walk towards that an "armed transient" is en-route). Hunting out-of-season, however, can be difficult (this is called poaching and will be probably be noticed); but it's possible that with effective planning, certain legal game could be found in reasonable proximity to much of the walking route. Nimur (talk) 23:42, 6 July 2009 (UTC)[reply]
If it isn't possible, then it is possible. Bring lightweight fishing gear, and a slingshot. I don't know what other advice to offer, but I too have wanted to walk across the United States. Bus stop (talk) 21:33, 6 July 2009 (UTC)[reply]
You'd also be trekking across large rivers (like the Mississippi), tall mountains (perhaps some with glaciers), major highways, and perhaps fences and private or restricted property (like Area 51). Bring a map, and some, erm, gear. Lightning is also a danger, as are flash floods, tornadoes, blizzards, and other elements of extreme weather. You might encounter bears or rattlesnakes in forests and semi-deserts. Also, where are you going to sleep and use toiletries? You can't possibly walk for 9 months straight, so there have to be suitable places you can stop every day and night. Also, if on the off-chance you happen to be walking in Nebraska when global warming hits, or close to Wyoming when the Yellowstone supervolcano erupts...you might be in a little trouble. And that's not to mention the 2009 flu pandemic (assuming you start your hypothetical journey in the near future), and if you're travelling through a large city, you'd have to use roads and maybe you'll get stuck in traffic and then you'd want to book a hotel. ~AH1(TCU)00:26, 7 July 2009 (UTC)[reply]
Walking across the U.S. without restriction, such as the ability to buy food and water in town as needed, and simply choosing to walk rather than drive, and camp rather than get a hotel, would be entirely possible in about a year or so. One could easily choose a path that would stick to major highways and you should be able to hit at least a rest area with a snack machine and clean running water every day or two. However, crossing the continent as though it were wild; living off of the land and avoiding all civilization would be nearly impossible. Lewis and Clark did it, but it was a well-funded government expedition with the cooperation of native peoples. It took them over a year to reach the Pacific from St. Louis. They left in May 1804, arrived at the Pacific in December 1805, and did not get back to St. Louis until September 1806. Add another 1000 miles to cover the trip from Baltimore, and if you assumed you had to travel under the same conditions they did, the trip the OP proposes would likely take 3-4 years, if you survived at all. --Jayron32.talk.contribs00:43, 7 July 2009 (UTC)[reply]
Also, the shortest journey would seem to be a straight line, but that would run you through Lake Michigan! Under that straight line, it's about 2,370 miles. You might as well stop in Chicago along the way, but it can be done—Terry Fox ran from St. John's, Newfoundland, to Thunder Bay, Ontario (3,339 miles in 143 days), but of course taking breaks every day at cities and towns, all the while with cancer and wearing a prosthesis! ~AH1(TCU)01:00, 7 July 2009 (UTC)[reply]
Hard to believe that noone has mentioned the American Discovery Trail which crosses the U.S. and has been thru-hiked. Apparently there aren't many hikers, campers or hunters among the answerers here. It isn't all that dangerous or impossible. Also hunting licenses are state issued (with extra stamps for migratory birds issued by the federal gov't.) - not by county. Rmhermen (talk) 01:20, 7 July 2009 (UTC)[reply]
50 pounds would be a punishing load to carry on the back. A bicycle would allow you to carry the load and to move at 15 miles per hour or faster on highways (if it did not count as part of the 50 pounds.) If you were afoot, the 50 pounds of load might support you for a month, and you would only be a small fraction of the distance from start to finish. You could carry 10 pounds of food, clothing and supplies on a 40 pound bike, and live off the kindness of strangers. If you carried a laptop, you could probably find hosts every 50 miles or so who would house and feed you free, allowing a 2800 mile trip (per Google maps) in 56 days. If you are a member of some religious denominations, and told them it was a pilgrimage or some such they would likely host you. Edison (talk) 02:12, 7 July 2009 (UTC)[reply]
A strong male hiker can easily carry 50 pounds 20 miles per day up and down mountains -- I've done it. But it takes 2 pounds of food per day to maintain weight if you're hiking long distances, and that's if the food is chosen very carefully, so 50 pounds won't get you through a month even if the bulk of it is food. (An ultralight hiker may get along with less than 10 pounds of non food/water weight.) Also, if you think you can find hosts every 50 miles, you haven't driven across Nevada. In any case, walking across the US is definitely doable if you can resupply with food -- however you'll be carrying well over 50 pounds for some stretches, most of it water.) Looie496 (talk) 03:41, 7 July 2009 (UTC)[reply]
"Easily??!!!" I say bullshit as to carrying a 50 pound pack up and down mountains 20 miles, except for Marines, Commandos or other Rambos. Wheeled transport would be more feasible. Why carry such a load if you can ride or pull it on wheels? There is a good highway system. I agree that a month would be an outside estimate for how long the initial 50 pound pack would support your food needs. As for water, there are lightweight devices for water purification which would suffice except in desert. Edison (talk) 04:59, 7 July 2009 (UTC)[reply]
Edison, 50 lb is heavy, yes -- a couch potato would certainly have trouble with it but for a well-prepared backpacker it is really not out of the ordinary. You have to assume that the person proposing to "walk across the country" is going to do the requisite pre-trek preparation (cardio, weights, endurance) so that they'll be in near-peak physical condition. If that person isn't capable of some pretty serious physical activity then the expedition is doomed from the start. --- Medical geneticist (talk) 12:50, 7 July 2009 (UTC)[reply]
Responding to Jayron32 above, "living off the land" isn't quite right for Lewis and Clark, as they acquired a great deal of food from Native Americans. And, differing from the OP's idea of walking (solo I assume), Lewis and Clark did not walk except when they had to but rather used boats with rowing crews and tow ropes to pull. And they had a party of (mostly) experienced wilderness travelers, some of whom were regularly assigned "hunting duty" in hopes of bagging some food for everyone else. In those days one was able to wander into the woods or prairie with a gun, hoping to shoot some animal (that was not the property of ranchers, etc, as mostly the case today) to feed your party. In any case, I'm hard pressed to imagine how one would "live off the land", without trespassing and stealing, while walking across Illinois, Iowa, and Nebraska, which have been almost completed converted to farms, not to mention Wyoming, southern Idaho or northern Utah, and eastern Oregon or Washington, as these regions semi-desert at best. Finally, if resupplying at stores is not allowed, and you are planning to hunt for food carrying a pack of less than 50 pounds, wouldn't you rapidly run out of ammo? Perhaps a shorter version would be feasible--say one state rather than the whole country. Pfly (talk) 08:15, 7 July 2009 (UTC)[reply]
There is also no longer "an abundance of elk and deer" in most places. (OR Even in the past 40 years or so the area where we live has changed from being out in the boonies with farms, woods and a couple of houses to being almost "downtown" Atlanta.) Apart from all the caveats on hunting cited above there's the fact that carrying 50lb you'd need a diet high in calories. Meat is high in protein. I sincerely doubt you'd have that easy a time finding passerbies in downtown Oakland willing to trade you a rabbit fur for a bag of flour, but you're welcome to try. Hiking the American Discovery Trail[20] has nothing to do with "living off the land". Hikers usually carry freeze dry food and bottled water. (I don't think your portable water purifier could handle the alkaline and Arsenic puddles you'll find in some places on the way [21]). There are stops on the way where you can buy or pick up provisions. Many parks it passes through are wildlife preserves and the rangers would probably toss you out pronto if you tried to hunt there [22]. It also passes over some private property and through towns and villages. As said above you can't hunt and hike at the same time. The trail has certain stages that depend on things like opening hours for parks. You can't do whatever you want where ever you want to do it, either. There are regulations in parks that limit where you can camp, what you can use the surface water for, where you can light fires etc. In some places you can't swim or bathe in the lake or river in the park, but have to use the official campsite facilities. You might be able to do what you are planning in some local places in the US, but finding enough of them in close enough proximity to hike across the US without picking up provisions is highly unlikely these days. 71.236.26.74 (talk) 12:38, 7 July 2009 (UTC)[reply]
I seem to recall reading somewhere that there are actually more deer now then when they colonized the US. Don't know about elk though. 65.121.141.34 (talk) 20:01, 7 July 2009 (UTC)[reply]
(further tangent) Deer populations plummeted in early colonial times due to the Deerskin trade, though there were probably other factors keeping numbers down (wolves etc). Pfly (talk) 08:57, 8 July 2009 (UTC)[reply]
I think the original question needs further clarification. What is "a survival scenario"? Is everyone dead from a super-virus, but the infrastructure is intact? Are you transported into an alternate reality where the continent is in pristine condition untouched by humans? Have you slept through the singularity and the land has lain fallow for a thousand years? "Survival scenario" may suggest that you don't need to bother with human regulations and local game laws... --Stephan Schulz (talk) 14:22, 7 July 2009 (UTC)[reply]
As many as 100,000 Americans are chronically homeless. Their health is poor, their morbidity and mortality is way above average, and they rarely have the energy to trek across the continent. But, many do live for a very long time. If the original poster is willing to adopt this sort of lifestyle, it seems plausible to self-sustain. But even a homeless person will use modern infrastructure (like buying food at stores and accepting charity every now and then). Few can survive a totally isolated existence. As has been pointed out, America is not the same place as it was when pioneers and explorers set out - even the undeveloped parts of the country are usually privately owned. Taking what you need for survival "from the land" relies on public-domain land (or murder and theft of other people's stuff). Both options are generally unacceptable in industrial society.Nimur (talk) 15:35, 7 July 2009 (UTC)[reply]
Nimur -- could you please keep politics and revisionist history out of this? Your comment about "murder and theft of other people's stuff" was really uncalled for. Thanks!
Is the mistreatment of natives not something that nearly everybody agrees has happened? If it isn't, I'm shocked. I know all about the extent of creationism, global warming denialism, and even HIV denial, but this? --Bowlhover (talk) 08:33, 8 July 2009 (UTC)[reply]
Nope, not denying that it happened, just disputing the allegation that it was the white race (my race) that started the whole conflict. As far as I've been able to decipher, it was the natives who first attacked Jamestown, in the same year that it was founded. As for "global warming denialism", please keep in mind that this whole "global warming" thing has not been conclusively proven yet, and in fact this year has so far been the coldest on record since 1989 -- so one could actually make the case that what is taking place is not global warming but global colding. So call me a denialist or even a racist, but that doesn't automatically mean that my views are wrong and yours are right.
"The white race"? "The natives"? So the Emperor of all Natives said to the King of the White People "I take this marble, and sell you the continent", and when the the harmless White settlers arrive, the Natives suddenly attack them? Such an understanding of history calls for a quote from Forrest Gump indeed.... --Stephan Schulz (talk) 07:19, 9 July 2009 (UTC)[reply]
How could the natives "sell" to the white settlers land that they didn't even own?! With all due respect, I think it's your understanding of history that calls for a quote from Forrest Gump. Besides, you're putting words in my mouth that I never said, and distorting the statements I made in my posts.
Well, what did you mean when you talked about "the white race" and "the natives" as if those where entities that are remotely useful in a historical debate? --Stephan Schulz (talk) 09:37, 9 July 2009 (UTC)[reply]
I meant exactly what I meant, the white settlers from Europe and the native Indian tribes. What do you mean by saying that these entities are not useful in a historical debate about what is essentially a racial and territorial conflict? Or are you trying to assert that the concepts of race and nationality in general are nonexistent and/or irrelevant? If the latter is what you're trying to say, then your statement flies completely in the face of all common sense and holds no water.
I alleged nothing. I merely stated the obvious - either the land resources must be in the public domain, or they must belong to somebody. If the OP intends to take things from the land (by hunting, etc), and does not want to exchange money, then the options are either to find public domain land (which does not exist in the present time), or to steal things from privately owned property (by force). It is up to you to interpret how that corresponds to historical precedent. 76.21.37.87's commentary suggests a limited perspective on history, though, as Jamestown is a very small part of a continent (which had been inhabited for thousands of years, and explored/colonized/traded/attacked/etc. by Europeans for at least a hundred years). Nimur (talk) 06:22, 9 July 2009 (UTC)[reply]
As far as your statements about the ownership of land resources are concerned, these are obviously correct and I do not dispute them. However, I don't think that your statement "It's up to you to interpret how that corresponds to historical precedent" is consistent with your putting in a link to "Population history of American indigenous peoples" and labeling it "murder and theft of other people's stuff" -- that sounds to me exactly like an allegation that the settlers had started an unjust war (which, I repeat, is not what is believed to have really happened back then). And as far as history is concerned, may I remind you that the Indians had no concept of land ownership and did not technically own the land -- and therefore, the whole continent was technically in the public domain at that time?
Someone more or less did walk across the US in modern times - probably the 70s. They wrote a book about it, which I read. Cannot remember his name. I think he did not, as far as I recall, complete the whole journey. Since lots of people cycle around the world, then lots of people must cycle across the US, which must be easier to do. 78.147.135.194 (talk) 23:55, 8 July 2009 (UTC)[reply]
I think it was Forrest Gump who walked across the US -- and yes, he did complete the whole journey.
Yeah, it was Peter Jenkins; I stand corrected. The reason I thought it was Forrest Gump is because that movie had an episode where he walks across America just because he feels like it and doesn't even realize the historic implications of his journey. That scene was no doubt inspired by Jenkins' journey, though.
In most towns, food could be obtained quite regularly by [Dumpster diving], if the restriction on resupplying from shops means not purchasing, rather than shops not existing. In between, all those regular sessions of getting arrested would also lead to free meals (and showers) in various local jails. But the price of getting out of them may exceed the planned budget. Doing odd jobs in exchange for food may also be feasible, unless the survival scenario excludes the existence of other humans (which would also put paid to the eating in jail idea, but make poaching easier). So, spare socks and shoes, lightweight rain cape/ground cover, several sets of clothing to layer for various temperatures, a rifle,fishing gear, digging tools (for vegetable foods found on the way), a light cooking pot and a LOT of matches. Notebook, pencils and camera to leave an explanation for those finding your remains.- KoolerStill (talk) 13:49, 10 July 2009 (UTC)[reply]
I've moved your comment to the main section "Walking across the USA" -- it must have been split into the "GW tangent" section by mistake.
As for "global warming denialism", please keep in mind that this whole "global warming" thing has not been conclusively proven yet, and in fact this year has so far been the coldest on record since 1989 -- so one could actually make the case that what is taking place is not global warming but global colding.
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- ::Setting aside the fact that "colding" is not a word, did you know that there's no debate amongst climate experts that significant anthropogenic global warming is happening? A distinguishing feature of cranks is that they claim something has "not been conclusively proven yet", when it fact it has. --Bowlhover (talk) 06:37, 10 July 2009 (UTC)[reply]
Where did you get the idea that there's "no debate" at all among climate experts about "global warming"? I've been to a conference on alternative energy a few weeks ago, and I've heard one of the experts there (a distinguished physicist, by the way) question the assertion that global warming is happening at all. Are you saying that he's a "crank", as you put it? And if, as you assert, it has been conclusively proven that "global warming" is happening and is manmade, then where's the proof?! What about the alternative (and very credible) explanation that "global warming" is caused by an increase in solar activity?! There's also a warming trend on Mars, are you saying that this is manmade as well?! Also, keep in mind that many of those who say that global warming has been "conclusively proven" have a vested interest in having people believe that: Al Gore, for example, so that he could make more money off his movie "The Day After Tomorrow"; environmentalist organizations looking for new recruits; developing countries, who would just love to have us here in America limit our economic output so that they could force us out of first place in GDP; and so on, and so forth. In fact, there's reason to believe that this whole "global warming" thing is a myth created by developing nations for the express purpose of harming the developed nations' economy. And last but not least, you haven't answered my question: HOW DO YOU ACCOUNT FOR THE COOLING TREND OBSERVED DURING THIS CALENDAR YEAR?
The "cooling trend" during this calender year is called "the weather", or possible "the seasons", depending on your location and scope of observation ;-). Please see our article scientific opinion on global warming for the support the mainstream opinion enjoys, and Talk:Global warming/FAQ for several of your misconceptions. I think the "developing nation conspiracy" is a new one, though...how exactly do they get all the first-world scientists and National Academies on board? --Stephan Schulz (talk) 09:23, 10 July 2009 (UTC)[reply]
You still haven't answered my question regarding the warming trend on Mars, which can only be explained by solar activity, and therefore supports the theory that the global warming seen on Earth is likewise at least partly caused by the aforementioned solar activity as well. As for "how exactly do they get all the first-world scientists and National Academies on board?", remember -- not all of them are on board, as I previously mentioned. Besides, in science it's all about the proof, not about the consensus; at one time or another, the mainstream opinion in science had embraced a whole bunch of theories that were later disproved, such as the geocentric universe, the phlogiston theory, the Lamarckist model of evolution (as opposed to the Darwinian model), Gobineaux's racial theories, the "general theory of relativity"... the list goes on and on. So just because (almost) all of the scientists say that it's so doesn't mean it's necessarily so.
No you haven't neither -- I've seen the section you refer to, and it doesn't give any explanation whatsoever for the warming trend on Mars, nor does it offer any meaningful evidence to refute the solar activity hypothesis, it just says that the other scientists don't agree with it, which by itself is not enough evidence to refute it. After all, when Copernicus said that the Earth goes around the Sun, nobody believed him either, but later on they found that his theory was the right one. As for 97% of active climatologists being in favor of global warming, remember that there are still the 3% who question it, and they might still be proven right. Remember, scientific theories are evaluated solely on their own merits, not on their popularity (even among specialists in the field).
Sigh. There is no reliable data for a global warming trend on Mars. We need about 30 years of data on Earth to get a reliable trend. Mars' year is twice as long. We have no global climate data on Mars even now. Do the math (and the logic). What we do have is an indication that some regions have less ice than two years before. Do you have a source for the claim that Copernicus heliocentric system was rejected by scientists at the time? Yes, scientific theories are evaluated on their merits. But isn't it interesting that 97% of those best equipped to do so come to the same core conclusions? And, BTW, those 3% are not contrarians - they include the undecided. And even among the contrarians, there is no agreement for any reasonable theory - after all, we have Singer's "unstoppable 1500 year natural warming" vs. Abdussamatov's "the next ice age is coming". --Stephan Schulz (talk) 11:38, 12 July 2009 (UTC)[reply]
I don't. Let me point out that arguments of the form "You don't know how it works, therefore the sun-god did it" went out of style with the pyramids. That said, if you look at Climate_of_Mars#Evidence_for_recent_climatic_change, you can see that there are reasons to believe that this is likely a local phenomenon, that it possibly is connected with the behavior and distribution of dust, and that it possibly is an effect of unstable climate shifting between different modes. --Stephan Schulz (talk) 09:04, 13 July 2009 (UTC)[reply]
May I point out that there are also "reasons to believe" the same about the warming trend seen here on Earth, based on some of the climatological evidence? There is still not enough evidence to say for sure if global warming is indeed manmade as you assert, or if it's also an effect of "unstable climate shifting" caused by changes in ocean currents or cloud cover or the like -- there just isn't. Only the future will tell which of these theories is right. And BTW, when did you see me mention "the sun god" in any of my posts?
You might want to ask yourself why you give so much weight to a tentative 3 (Martian) year trend in certain local features on Mars, and so little to 150 years of instrumental records, millennia of fine-grained reconstructions, a well-understood radiation model (that predicted warming of the right order of magnitude long before we could begin to measure it) and heaps of other data. You're welcome to your opinion. I'll stick with all the National Academies of Science, thanks. Sun, Sun-god, it's all the same to me ;-). --Stephan Schulz (talk) 22:34, 14 July 2009 (UTC)[reply]
I really recommend that you check out the article "Global warming controversy" -- it features both the "mainstream" view and the various dissenting views, for which there's much more support in the scientific community than you think (Pielke, McEntire, Armstrong, among numerous others). Then you'll see that there is indeed continuing debate about the validity of global warming, and maybe you might even begin to form an informed opinion of your own, as opposed to merely repeating what the mainstream scientists say.
Pielke supports the main IPCC conclusions - he just thinks we overemphasize global and underemphasize local effects. Armstrong is a Professor of Marketing, for all that's worth. McEntire is a musician - do you mean Stephen McIntyre? --Stephan Schulz (talk) 11:28, 10 July 2009 (UTC)[reply]
Yeah, I meant Stephen McIntyre -- I must have subconsciously confused him with Reba McEntire. As for Pielke, if you go to the Global warming controversy article and read it carefully, you will see that he actually questions several of the IPCC findings. Plus, there are quite a few other scientists that the article mentions by name who question the global warming theory, whose names I omitted from the list to avoid making it too very long.
Given the abundant thorns, and a lack of anything else identifiable, this could be a variety of thistle, or perhaps a member of the rose family, perhaps some variety of wild blackberry. The leaf shape does remind me of blackberry; but that leaf shape is fairly common and not a good identifier. Do you have any other pictures which show flowers or fruit or other distinguishing characteristics? --Jayron32.talk.contribs19:14, 6 July 2009 (UTC)[reply]
I'm in the UK, so your foliage may differ, but that looks identical to the wild blackberry ("a widespread, and well known group of several hundred species, many of which are closely related apomictic microspecies native throughout the temperate Northern hemisphere") or bramble that has latterly taken over my back garden (gardening is not my favourite occupation). Since blackberry picking was historically a popular pastime, it does not seem unlikely that this plant - if not already present - would have been deliberately introduced to a New York park. I trust the park staff will be able to keep on top of its vigorously spreading habits. 87.81.230.195 (talk) 19:39, 6 July 2009 (UTC)[reply]
The fuzziness was making me think more dogrose than bramble, but it would be easier to tell with more pictures of more developed bits. Any fruit or flowers would help. 89.168.106.72 (talk) 02:29, 7 July 2009 (UTC)[reply]
Here are some more pictures, but it didn't have any flowers or fruit. [23][24] I don't think I've ever seen fruit on it. I may have seen this plant with small white flowers a while ago but I'm not sure. Doodle77 (talk) 02:38, 7 July 2009 (UTC)[reply]
Looking at your other pictures, I am not sure we can get any closer than something in the Rosoideae (rose) family. Dog rose or blackberry or raspberry or any of a number of similar plants will produce similar thorny bramble. If we could see the fruit, we could tell if it had berrys or hips and that would help narrow it down. Likewise, the flowers could be helpful. But given that the plant is not currently flowering or fruiting, it is hard to narrow it down more than that. --Jayron32.talk.contribs03:43, 7 July 2009 (UTC)[reply]
Looking at those pictures hardens my gut feeling that it isn't bramble (blackberry-type) but a wild rose. The stems look too thin and smooth, and the thorns too 'fuzzy', for bramble. Small white flowers support bramble, though. Hmmm. 89.168.106.72 (talk) 04:01, 7 July 2009 (UTC)[reply]
Smooth stem doesn't rule out bramble. If the plant developed from an offshoot or fruit of a bramble bush in s.o.'s garden that e.g. got dropped in the park by a bird, then it is possible that it is in the process of reverting from a "thornless" cultivar back to the original thorniness. Lots of cultivated varieties of the Rosoideae do that if left to their own devices. 71.236.26.74 (talk) 09:24, 7 July 2009 (UTC)[reply]
Penis
I know that all the penis enlargment pills currently avaialble are just scams but is there any promising and genuine scientific research going on to develop a pill that really does work to enlarge the penis?
No. If anything were remotely promising, it would already have been headline news in every media outlet just as Viagra was the top of the news everywhere when it just began the first round of trials. -- kainaw™19:30, 6 July 2009 (UTC)[reply]
i have seen penile enlargements; but was always shy to ask its owner the cause.
still don't believe in those wierdos who advertise on enlargements; as they are only out to plunder your bank!!Seacucumber06 (talk) 06:16, 7 July 2009 (UTC)[reply]
Every day in my email, I get people trying to sell me Acari Berries. What the hell are these things? They claim that they're some sort of new fruit that was found in the Amazon that if eaten regularly can cause weight loss, increase lifespan, prevent cancer, cure various diseases and even enlarge the penis and increase sperm count. I know that it's all quack rubbish but seriously, what is the Acari Berry?
See Açaí Palm. You can blame Oprah for this. Her show claimed that it is a wonder-drug and now the scammers are using it to lure idiots people into handing over their credit/bank info. -- kainaw™19:27, 6 July 2009 (UTC)[reply]
[[25]] This might be something akin to what your asking but doesnt increase size of the penis; however if you eat a whole bag of these it does have a sort of natural vigra effect; i found this out while eating a large bag :) 214.13.64.7 (talk) 04:44, 13 July 2009 (UTC)[reply]
Bird Rescue
Oh no! A pre-flight baby bird has been grounded in my back yard. Luckily, the mother—who appears to be a robin—is still taking care of (i.e. feeding) the thing. Now, I know nature is cruel and everything—but, I mean, c'mon, the little guy is right out there with the whole open mouth routine and everything, and evolution has been sloppy about making sympathy a human-exclusive. I fear that if I leave the robin on the ground it might fall prey to—well—a predator. Is there any simply way to elevate it or something to keep it relatively safe for the night? (I live in a NE US suburb—maybe predation is not much of a threat?)
Do you have something against the cute furry little predators? They have to make a living too. Those fox puppies are just SO cute...and soooo hungry - and you're denying them lunch - what a heartless brute! :-) SteveBaker (talk) 01:27, 7 July 2009 (UTC)[reply]
You could contact a Licensed Official Wildlife Rehabilitator, who might take the wee bird away and care for it, or who might take it away and kill it (I have read of such results), or you could try putting it back in the nest (having observed which nest Mom and Dad bird are rearing the siblings in). Do not attempt any hazardous tree climbing. Edison (talk) 01:57, 7 July 2009 (UTC)[reply]
Usual advice is not to add it back to the nest, as handling the chick can result in scaring the parents away and disturbing the nest can lead to it being abandoned (at least, when I've been in this situation, this is what we were told). You might get away with putting the chick on top of something tall and difficult to climb (like a wheelie bin or bird table), but generally if the parents don't manage to take care of the fellow and get it flying, its only hope of survival is probably you hand-rearing it (so, taking it inside, in a lined box, and feeding it and providing it with water). 89.168.106.72 (talk) 02:23, 7 July 2009 (UTC)[reply]
The advice you cite, about not handling the chick, is contradicted by the RSPB link above; but the RSPB link talks about "UK birds" having a poor sense of smell...which begs the question, is it OK to handle birds in other countries to get them back in the nest? Tempshill (talk) 03:28, 7 July 2009 (UTC)[reply]
Wildlife experts routinely remove young peregrine falcons from nest to weigh them, take blood samples, and band them before returning them to the nest. The parents watch and complain somewhat, but do not reject the young when they are returned to the nest. Edison (talk) 14:18, 7 July 2009 (UTC)[reply]
I'm not an ornithologist or a wildlife expert in general, but from what little that I do know about birds, you could try to put the chick back in the nest, just be VERY, VERY careful not to damage or disturb the nest in any way.
76.21.37.87 (talk) 06:29, 8 July 2009 (UTC)[reply]
Placing the bird on an elavation is just as good - Garage roof - but not neccesery the reason the bird has left the nest is it is learning to fly (can cover very small distances). Most young chicks will stay close to the nest when fledging; this is usualy on the ground not at the top of a tree and will stay in the surrounding area for a week or more near the nest site. The parent birds will still feed the chick for this period. in the case of some birds (Doves) the parents will lay twice or even three times in a season depending on the country, only when they have layed another brood of eggs will they stop feeding the first brood.214.13.64.7 (talk) 04:56, 13 July 2009 (UTC)[reply]
What would be the efficiency of a facial mask designed to be 95% effective in filtering particles that are 0.3 μm in size? Would the clustering of viruses with each other affect this efficiency? ~AH1(TCU)13:42, 7 July 2009 (UTC)[reply]
Most influenza viruses are transmitted in small droplets, not by themselves, so the mask will offer some protection though I can not give a %. 65.121.141.34 (talk) 14:25, 7 July 2009 (UTC)[reply]
Page 9 of this pdf, produced by the NHS (the UK health service), says: "[T]he available scientific evidence shows that these basic face masks don’t protect people from becoming infected." The NHS recommends good basic hygiene (catch coughs and sneezes in a tissue, bin the tissue and wash your hands) as being far more effective (see that pdf for details). --Tango (talk) 15:20, 7 July 2009 (UTC)[reply]
When someone sneezes or coughs, do they emit individual virus particles, or are the virus particles part of a much larger droplet of fluid? Edison (talk) 15:27, 8 July 2009 (UTC)[reply]
They are within droplets of fluid. As for the masks, I've always been of the opinion that the chief function they serve is to constantly remind you not to play with your nose and mouth (without washing your paws first, anyway). Matt Deres (talk) 02:45, 11 July 2009 (UTC)[reply]
Solar cell from calculator harnessing
Can one create a decent solar panel out of the solar cells found in solar powered calculator? If yes, how many do I need and how should I stick them together. The resulting solar cell aggregate should at least power a small electric fan or light bulb. Just curious.--Lenticel(talk)01:03, 7 July 2009 (UTC)[reply]
Since each photovoltaic cell from a calculator only creates a small voltage at a small current, you must connect them in parallel to increase the current, and connect these units in series to get the required voltage. If you take a photovoltaic unit out of a calculator, you can use a multimeter to determine its output characteristics in sunlight. You can use a battery and a rheostat to determine the minimum current and voltage needed by your chosen load. An LED light would be a better choice than an incandescent bulb (like a regular flashlight bulb) to be powered by an array of such photocells. Edison (talk) 01:52, 7 July 2009 (UTC)[reply]
Thanks. I just thought just now how "ungreen" this would be since you'll be discarding a lot of useful electronic gadgets for something that can only power a small appliance/light.--Lenticel(talk)02:36, 7 July 2009 (UTC)[reply]
You can buy photocells at your local RadioShack or other electronics hobbyist store; or at any internet electronic component distributor. This way you don't have to destroy calculators to power your hobby-projects. Nimur (talk) 14:44, 8 July 2009 (UTC)[reply]
assessing potential fish stock / resources in a region
how does on assess the existing marine resources, especially fish stocks in a particular region, given the scenario that the stocks are declining due to myriad of reason; especially fishing pressure? —Preceding unsigned comment added by Seacucumber06 (talk • contribs) 06:06, 7 July 2009 (UTC)[reply]
These sound like handwavey approximations for qualitatively comparing different fishing operations (e.g. if it takes more effort to catch salmon than halibut, there is a better halibut catch per unit effort, even if more tons of salmon are bought). The Manual of Methods for Fish Stock Assessment from the Food and Agriculture Organization of the United Nations talks extensively about both terms, but does not appear to define "effort" - my guess is one "unit" of effort could be considered one boat on location for one day, or some similar unit of fishing effort. The source even mentions that a biologist and an economist will differ on definition of "effort" exerted by the fishing crew. Nimur (talk) 15:55, 7 July 2009 (UTC)[reply]
I am not a commercial fisherman, but it sounds to me like these are ways of quantifying the efficiency of a fishing vessel. "Catch per unit effort" would be the amount of fish caught divided by the "effort" that was taken to catch them. "Effort" is probably measured in time or, more abstractly, money that was spent on the ship rental, crew, and gasoline. The "catch per unit effort" number would be high if the ship catches a lot of fish with little cost. The importance of the number is that a more efficient ship will earn more money over time. (Aside: There are 1.3 million mechanized fishing boats out there. We're doomed.) Tempshill (talk) 16:00, 7 July 2009 (UTC)[reply]
Coriolis effect
I read the first few lines of the article but I cannot understand how it would effect sniping or long range shooting of unguided weapons. So how does the Coriolis effect effect sniping etc.?--116.71.62.75 (talk) 07:34, 7 July 2009 (UTC)[reply]
The Coriolis effect is a fairly simple concept. Any object which is moving through the air, and thus is no longer in contact with the solid earth, is only carried forward by its own momentum. The Earth underneath the object is not stationary, however, it is moving along at a good clip, roughly Template:Mi to km per hour at the equator and slower the farther you get from the equator, down to motionless at the poles. Since a flying object is not in contact with this moving ground, the place that object will land can only be determined considering both the motion of the object, and the motion of the earth, which is somewhat complicated given that, unless the object is projected directly along a line of latitude, the earth's linear speed under the object will be changing as the object changes latitude. This changing speed of the earth under an airborne object is really what is meant by the "Coriolis effect". For a sniper's bullet, the bullet itself moves too quickly over too short a distance for the Coriolis effect to make anything but a trivial change on the flight path of the bullet; wind effects would likely cause more of a problem. For an ballistic missle, however, which is likely flying thousands of miles, one had better consider the motion of the earth if one wants to accurately hit the target. --Jayron32.talk.contribs11:15, 7 July 2009 (UTC)[reply]
This answer may be confusing; the important thing is not that that the Earth is moving, but that it is rotating. The projectile once fired tries to move in a straight line as seen in a non-rotating frame of reference, but this is not a straight line when projected onto the Earth's rotating surface.
For example, say the projectile is fired straight north from the equator. As noted, the Earth's surface is moving eastward at over 1,000 mph, more accurately about 1,040 mph, at that latitude. So the projectile starts with 1,040 mph of eastward motion in addition to its northward motion. Say it reaches a latitude where the Earth's surface is now moving east at only 960 mph. Then the projectile is moving 80 mph faster to the east, and it will seem to have curved to the right in flight. That is the Coriolis effect. It works the same way no matter where on the Earth's surface you start from, but I picked this example because it is an easy one to visualize. --Anonymous, 20:46 UTC, July 7, 2009.
In an earlier discussion of the Coriolis effect, a poster said it resulted from a projectile moving closer to (or farther away from) the earth's axis. Even though the projectile stays above the earth's surface, that applies unless the motion is due East or due West. I find it easiest to think of this by imagining the projectile moving over a rotating disc toward the axis of rotation or away from it. The projectile's motion need not be directly toward (or away from) the axis of rotation as long as there is a component of motion in that direction. —Preceding unsigned comment added by 98.17.38.231 (talk) 22:41, 7 July 2009 (UTC)[reply]
Iris scans can be used to uniquely identify people. The UK government is building up a database of them, one way or another. I can also imagine that they could be used to identify wanted people in other countries. My question is, from how far away could you do an iris scan?
I assume an iris scan could be done from a detailed photo of an iris. Such a photo could in theory be taken with a very powerful telephoto lens on a fixed mount. Perhaps illumination by an infra-red or ultra-violet laser could be used to overcome some problems with nightime or haze. The most difficult problem may be aiming the telephoto at the eye on a moving target, but since even cheap digital cameras can find people's faces for auromatic focusing, and the image could be directed into the telephoto by an automatically movable mirror, then its easy to imagine that a computerised aiming system could be set up to do this.
I'm asking my question because I'm wondering if the UK government is going to start recording peoples identities from remote iris scans as they move around the country in the same way that they do now with automatic recording of car registration plates. 78.149.207.75 (talk) 09:50, 7 July 2009 (UTC)[reply]
According to Iris recognition#Disadvantages, such scans work at "a few metres" and claims for up to 10 metres are being made. I'm sure HMG, or elements in it, would love to introduce an ANPR system for irises (sp? - apparently irides. Who knew?), but I think we're a fair few years away from this being possible.
You say "the UK government is building up a database of them, one way or another". Do you have any evidence for this, or is it merely a wild assertion? --Tagishsimon(talk)10:03, 7 July 2009 (UTC)[reply]
It's not a particularly wild assertion. The government has made no secret of the fact that it wants to build a national ID database, with or without ID cards, and there have been fairly undisguised policies to increase the number of people on the DNA database. Iris scans have been something often brought up as being something they would want to include. National Identity Register and Information to be contained on the National Identity Register, for a start, or have a look back through the BBC archives. 89.168.106.72 (talk) 18:59, 7 July 2009 (UTC)[reply]
An example of remote iris scanning is here http://www.cl.cam.ac.uk/~jgd1000/afghan.html I guess you could take similar photos from perhaps even kilometres away with the right specialised equipment. Snipers with modern equipment can, I understand, shoot people from one or two kilometres away.
The UK is gathering biometric information for passports, the new ones are now all biometric passports. I thought they did include iris scans, but I expect they will soon include them. I think this information, and that from the proposed UK identity cards is going to be held here: Information to be contained on the National Identity Register Although the article only mentions fingerprints currently, there is nothing to stop iris scans being added, and they are already systematically used in other countries. I do not trust the government to refrain from using a surveleillance technology particularly when it is not being monitored, being brought to account, or even breaking the law. 78.149.207.75 (talk) 10:32, 7 July 2009 (UTC)[reply]
I drive an ancient and battered peugeot 306, which has few frills. About five minutes after turning the engine off, a noise like a solenoid actuating is heard. What would it be? fwiw, it appears to me to have nothing to do with the radiator fan. It takes a good second or so to make its noise. I'm baffled. --Tagishsimon(talk)10:17, 7 July 2009 (UTC)[reply]
The fan solenoid seems like the most likely explanation - but then you'd hear the fan shutting off too (assuming your fan is actually working!). Another possibility is that the thermostat that controls water flow into the engine block is making a noise as it shuts...although that's not anything I've ever heard (but then I've never owned a Peugeot 306). Another possibility is that as everything cools off (and consequently gets smaller due to no longer having been thermally expanded) some mechanical part is pushing against another - then suddenly slipping. There are too many possibilities to narrow that last one down. SteveBaker (talk) 14:38, 7 July 2009 (UTC)[reply]
Why do we have nerves in our teeth?
The cause toothache when exposed, but do they have any function at any other time? Woudln't we be better off without them? --rossb (talk) 11:03, 7 July 2009 (UTC)[reply]
Pain causes you to wish to fix the problem causeing the pain. If avoiding tooth pain causes you to take care of your teeth; the nerves are doing their job. --Jayron32.talk.contribs11:20, 7 July 2009 (UTC)[reply]
They are also part of the system that tells you how hard you should chomp down and whether the animal between your teeth is still wiggling or already dead. If the Prey is so strong it will make your teeth hurt it would historically probably have been a good survival strategy to let go of it before it broke your jaws or chipped your teeth. Telling the difference between biting a pebble or a nut comes in the same vein. 71.236.26.74 (talk) 12:47, 7 July 2009 (UTC)[reply]
I think you'll find that the nerves in teeth have functions you're not aware of. I expect it helps with mastication, with moving food around in the mouth, with knowing when to swallow particles, and other mechanics of the process. —Anonymous DissidentTalk13:05, 7 July 2009 (UTC)[reply]
I asked a dentist this once. He said it was an effect of how teeth form, and that the nerve in the tooth has no value.. He explained that the nerve forms first, then forms little loops (one for each tooth) and these nucleate the tooth-forming tissue. This nerve doesn't provide any subsequent benefit - it's different nerves that serve the ligaments and provide the sensation of pressure on the tooth. 87.113.26.43 (talk) 14:17, 7 July 2009 (UTC)[reply]
I'm pretty sure your dentist must be wrong. Toothache is pretty debilitating - especially in times before dentists and pain-killers existed - it would cause the victim to be a less effective hunter - to want to avoid eating - and would certainly make mating less likely. So it's hard to believe that evolution would allow these 'useless' nerves to continue to exist if there wasn't a REALLY good reason for them to be needed. Hence, I'm inclined to believe Anonymous Dissident's explanation and to write off your dentist's explanation. He's probably right about how they form - but wrong about the lack of subsequent benefit. SteveBaker (talk) 14:42, 7 July 2009 (UTC)[reply]
Don't write off the local dentist just yet. Doctor Spiller's explanation is interesting, and he includes why the nerve tissue is important throughout life, to stimulate production of dentin. As to whether the nerve (as in a neuron) forms first, I'm not so sure on that, it looks like it's actually patterning of mesenchymal cells (which are cells from the neural crest) in the embryo and the development of axons from the actual nerve cell itself matches that patterning, but our tooth development article is tough reading. Why the neuron is connected to a pain centre in the brain is unclear. I suppose it has to be connected to something to survive, and the pain sensation would stimulate production of more dentin to better cushion the tooth? It may be a little of both explanations. It's certainly true that when the nerve gets taken out, the teeth are more likely to fracture, I can tell you that for sure. :( The severe pain of a toothache may just be one of those evolutionary tradeoffs. Acute pain from biting on a rock would be adaptive. Chronic pain from a cavity is much less clear - what possible adaptive value is conveyed to the organism? Franamax (talk) 17:08, 7 July 2009 (UTC)[reply]
I'm pretty sure that tooth aches were around before any sort of viable treatment options were developed. While cavities are definitely bad, there's no evolutionary pressure if there's nothing people could do about it. Rckrone (talk) 18:33, 7 July 2009 (UTC)[reply]
As Rckrone says, that constant dull pain doesn't "teach" you anything - however it would lead you to avoid chewing with that part of the mouth, so might avoid further damage. Abscesses can certainly cause death, so in adaptive terms we're faced with the ugly prospect that dental treatment developed early, i.e. the unbearable pain would lead you to rip a tooth out of your own jaw before it killed you.
Basic body plan is a very fundamental aspect of evolution and development, so selection pressure needs to be large to counter it. According to thisNature (journal) article (email me for a copy), denticle formation is dependent on cells from "neural crestmesenchyme (from the trigeminal neural crest stream", so it seems as though innervation and the very existence of teeth may be inextricably linked. I'd somewhat disagree with Steve Baker that having a toothache would prevent you from having sex. Primates and early humans presumably lived with considerable pain from numerous sources. And in any case, so long as you reproduce before your teeth go bad, the job is done.
Interestingly, tooth pain may have actually been a "forcing" factor in human evolution. Looking at these online sources [26][27], this may have driven increased processing (and thus nutrient availability) of food. When someone was forced to boil their food to soften it, they may have discovered that it was now better food. And humans surviving to a later age of life would be better able to ensure that their progeny survived. Franamax (talk) 20:24, 7 July 2009 (UTC)[reply]
Without nerves in your teeth, you'd be breaking them constantly. If you bit down on a rock, you wouldn't know it until you heard the tooth breaking. Those nerves give you an awareness of the texture of what you're chewing on. Looie496 (talk) 21:34, 7 July 2009 (UTC)[reply]
No, you wouldn't. The sensation of pressure in your teeth comes from different nerve endings, embedded in the ligaments that hold the teeth in. The dendrites of the nerve inside the tooth are embedded in the dental pulpus, which is inside the rigid dentine shell of the tooth. Those wouldn't register anything on ordinary chewing; the pulpus will be disturbed only after you've broken the tooth on a rock. The falsity of your claim is evident to anyone who has had a root canal done; the tooth no longer has a nerve within it, but retains the normal bite sensation nevertheless. 87.113.26.43 (talk) 22:50, 7 July 2009 (UTC)[reply]
The hypothesis that abscesses in the teeth would teach people to be careful doesn't seem to have applied to people in Ancient Egypt who seemed to prefer their bread with lots of grit from grinding. Dmcq (talk) 13:10, 8 July 2009 (UTC)[reply]
Wikipedia cannot give you medical advice. Also, your Intraocular implant link points to an empty page, so we don't know what article you read (did you mean Intraocular lens, like in the section title?). As far as your research would go, it would probably be good if you looked into sources beyond youtube. Your best bet would be to contact a medical professional that performs these operations, or just your general eye doctor, get a professional consultation, as well as some other more reliable avenues of research. —Akrabbimtalk16:37, 7 July 2009 (UTC)[reply]
Late teens/early twenties
Are there any differences between someone in their late teens and early twenties in terms of physical, mental and emotional maturty? 86.166.47.44 (talk) 14:04, 7 July 2009 (UTC)[reply]
Yes - it's fairly well established that parts of the brain relating to self-control are still developing at late as age 18. SteveBaker (talk) 14:31, 7 July 2009 (UTC)[reply]
Yeah, people who study this stuff often consider about 25 years a good rule of thumb for having an "adult" brain. Physically, I don't really know. Friday(talk)14:45, 7 July 2009 (UTC)[reply]
Mid-twenties also provides a more mature body. There are many illustrations of this. For example:- Bones are finally fusing: while the body is growing, many of the joins between bones are soft cartilage. This turns to bone once growing is complete (for example, in the skull, ends of the jaw, collar bone etc). (Men's bones fuse later than women's.) Men broaden and put on muscle bulk. Final teeth have come through. Women are physically more suited to child-bearing in the mid to late twenties than they are in their teens. And so forth. As for emotions, the experience of living life matures people. Gwinva (talk) 23:01, 7 July 2009 (UTC)[reply]
Apparently (according to Dr Karl's radio show) you can tell when your brain is adult by when you switch to adult sleep patterns (but of course there's such great variety in humans that this won't always be useful) --Polysylabic Pseudonym (talk) 06:44, 8 July 2009 (UTC)[reply]
Is this a weevil?
I took this[28] picture this weekend in the Norfolk Botanical Gardens. I think its a Weevil, but either it has no probiscis (if that's what it is) or it is tucked away. I've dug around the weevil & related pages, and haven't seen anything like it. It was found early Saturday morning, sitting on a tall piece of grass, in a field. Keegstr (talk) 14:17, 7 July 2009 (UTC)[reply]
To be more specific, it could be in Pseudocneorhinus genus or closely related; one of the Entiminae genera clustered around Trachyphloeus. That's my guess. --Dr Dima (talk) 19:05, 7 July 2009 (UTC)[reply]
Car engine clapping
To be clear about the reason for this question... I am trying to convince my brother, through email, that he needs to take his car to a mechanic because he cannot diagnose the problem just by listening to the engine while he's driving down the road.
What could cause a 97 Corolla to make a clapping sound while accelerating, very similar to a Harley motorcycle? -- kainaw™14:53, 7 July 2009 (UTC)[reply]
My first guess would be that the muffler is bad... if it is loose or slightly obstructed. However, if there was a hole or leak, the muffler would sound more "howling" than "clapping". If the sound is definitely coming from the hood, it could be a lot of things - loose valves in the engine block, loose bolts somewhere... how severe is the noise? Nimur (talk) 16:04, 7 July 2009 (UTC)[reply]
A related exhaust-system problem, one that older cars often get, is partial failure of the matrix of the catalytic converter. In this, the honecomb elements melt and then resolidify, causing a blockage. This happens repeatedly, and unpredictably, making a changing variety of odd sounds and sometimes leading the engine, which is failing to exhaust spent gas properly, spluttering. The only fix is a new cat. 87.113.26.43 (talk) 20:08, 7 July 2009 (UTC)[reply]
It's tough to describe sounds in a way that gets other people to understand them. There's a few broad possibilities here. Is this an exhaust sound, or something else? (Engine sounds will often be things you can duplicate while not moving. This is nice because someone could stand outside the car and listen to it, for example.) Friday(talk)16:09, 7 July 2009 (UTC)[reply]
The first thing in diagnosing any weird car sounds is to ask the following questions:
Does it do it when the engine is running but with the car not moving? (This eliminates wheels, axles, brakes, etc)
Does the sound get higher in pitch or more frequent when you rev the engine while standing still? (If so, then the noise is being made by some part of the engine rather than some kind of sympathetic vibration).
When you are moving, does the sound get higher in pitch or more frequent as the car is moving faster or only as the engine revs change?
Does it only happen when you go around corners?
Does it only happen when you accelerate?
Does it only happen when you brake?
Does it only happen at a particular range of speeds? Or perhaps at a particular range of RPM's?
Does it depend on the weather?
Does it only do it when the engine is cold? Or perhaps only when it's hot?
Does turning on and off any accessories (radio, A/C, fans, etc) make a difference?
Perhaps - but my advice (above) on how to narrow down what the noise means comes entirely from distilling down thousands of hours of CarTalk advice. SteveBaker (talk) 03:06, 8 July 2009 (UTC)[reply]
It's too bad that the WP RefDesk isn't on the radio, we could have endless fun making the poster imitate the noise. APL (talk) 04:01, 8 July 2009 (UTC)[reply]
As good as I'm sure that advice is, are you sure that the questioner wasn't more looking for a giant list of possible engine problems to bowl his brother over and convince him to take the car to a mechanic? APL (talk) 04:01, 8 July 2009 (UTC)[reply]
Our OP asserts that his/her brother cannot diagnose the problem just by listening to the noise. However, the whole CarTalk thing proves that it is indeed possible to diagnose an awful lot of problems - not just by hearing the noise - but even by having someone humorously impersonate the noise over a crackly phone line while you openly mock them in front of millions of people! There are a large class of car problems that can easily be diagnosed by paying attention to when the noise happens. More than that - if the noise happens when the car is stationary - then right there you can say that this is almost certainly not a dangerous situation - but if it happens only when you turn left or right - then you'd better get your car looked at ASAP because you could easily die as a direct result of delaying another day before you get it looked at! For those reasons alone, I recommend carefully considering the list of questions I posed. Each one of them is designed to eliminate (or reinforce) a particular set of very specific faults. SteveBaker (talk) 04:57, 8 July 2009 (UTC)[reply]
"the whole CarTalk thing proves that it is indeed possible to diagnose an awful lot of problems ...\ by having someone humorously impersonate the noise over a crackly phone line while you openly mock them in front of millions of people!" Haha! Well put. APL (talk) 12:50, 8 July 2009 (UTC)[reply]
Thanks. I sent all these problems to my brother. He is still 100% positive that it is the catalytic converter and plans to remove it and place a connecting pipe where it used to be. He's stuck in one of those "the guys at the bar said..." mindsets. Apparently, they told him that removing the catalytic converter will also greatly improve his gas mileage and that the only reason we have them on cars is to reduce gas mileage since they have no affect on unleaded gasoline. So, I just have to wait for the "guys at the bar" to be proven wrong yet again. -- kainaw™12:56, 8 July 2009 (UTC)[reply]
Oh, removing the catalytic converter will improve his mileage. It's also illegal (in most jurisdictions, anyway) and will cause a failure of any emissions test he needs to pass. — Lomn13:24, 8 July 2009 (UTC)[reply]
I agree with Lomn on both points. This is not an acceptable course of action. When he goes in for his annual emissions check (which is mandatory in most states), somebody will notice. Nimur (talk) 14:22, 8 July 2009 (UTC)[reply]
The mileage improvement may or may not happen depending on the precise design of the car. Some engines need the back-pressure of the stock exhaust system - others benefit from having a free'er flowing exhaust. Some engine management computers get confused and wave check engine lights at you - on rare occasions causing them to drop into "limp home mode"...hence your mileage might get worse...or perhaps better...or you might find that you car will no longer let you go faster than 30mph! Ditto for horsepower - it's often assumed by 'ricers' that a free'er flowing exhaust buys you 5 horsepower - often, they are deluding themselves. But for sure, there will be considerable additional noise - and that may awake a policeman and that would put you into a world of hurt in some jurisdictions where deliberately circumventing anti-pollution devices can get you into massive amounts of trouble. And absolutely for sure, he'll have to put the cat back when he next has to go for an emissions test. This "fix" really isn't recommended for street cars - and right now, it's not even clear that it would fix the problem because nobody has properly diagnosed that it even IS the exhaust system that's at fault. SteveBaker (talk) 20:35, 8 July 2009 (UTC)[reply]
Oh - and kainaw...if you really need to PROVE that your brother is an idiot - read catalytic convertor - the things that the cat does have nothing to do with removing lead:
Reduction of nitrogen oxides to nitrogen and oxygen: 2NOx → xO2 + N2
Oxidation of carbon monoxide to carbon dioxide: 2CO + O2 → 2CO2
Oxidation of unburnt hydrocarbons (HC) to carbon dioxide and water: CxH2x+2 + 2xO2 → xCO2 + 2xH2O
...all of which are just as important with unleaded gas. Worse still (and the thing that PROVES he's an idiot) is given in Catalytic_convertor#Poisoning which points out that not only do modern cat's not remove lead - but running leaded gas through a catalytic convertor actually destroys the thing. So FAR from them being ineffective with unleaded gas - it's actually the case that they only work at all with unleaded! Tell him "Steve says' you're an idiot." SteveBaker (talk) 20:41, 8 July 2009 (UTC)[reply]
Surely you can be diplomatic - tell him "Steve says you know nothing about catalytic converters" or something...? After all, he's family... Nimur (talk) 23:23, 8 July 2009 (UTC)[reply]
And the important thing is not proving him an idiot; it is finding some means to get him to listen to reason instead of drunken idiots. At least this is less harmful to him than the case in which they convinced him that you could quit paying your mortgage and as long as you kept your family dog in the house, the police couldn't evict you. -- kainaw™12:49, 9 July 2009 (UTC)[reply]
Really? Wow, you learn so much from Wikipedia. Would it work with our tortoise or does it have to be a dog? Also sadly I don't have a mortgage but could I stop paying my electricity bill instead? --BozMotalk13:05, 9 July 2009 (UTC)[reply]
adding to an entry for my employer, a state agency
Hi,
I work in the Office of Public Affairs for the California Dept. of Public Health.
In researching the agency I found only a brief wikipedia entry that mentioned the Medical Marijuana Program and a news story about fees for vital records requests.
I am in the process of expanding the entry to provide information about the Department and its programs in a very neutral way.
I realize it may appear to be a conflict of interest but I do think expanding the entry would help Wikipedia users learn more about the agency and the services it provides.
Any advice/input from other Wikipedia users is appreciated.
If you want to completely avoid COI, locate references that may be used to expand the article. Post links to those references on the discussion page for the article and ask others to read the references and expand the article. Of course, if you use good references to back what you place in the article, COI should not be an issue. -- kainaw™15:35, 7 July 2009 (UTC)[reply]
(WP:OR) During our training for dealing with unruly students/residents, we had a presentation by our campus police (who are deputies of the Santa Clara County Sheriff, e.g. "real" police). They also gave us a brief talk about medical marijuana. According to hat discussion, even the police were not sure if medical marijuana is legal or illegal ("on a case-by-case basis"), and so they tend to "avoid" dealing with it unless the quantities involved are very large or some other law is definitely being broken. It seems that California law is so confusing and self-contradictory with regard to this subject that it is hard to make sense of it. When writing your article, bear in mind the legal disclaimer, and definitely stick to reliable sources. Nimur (talk) 16:16, 7 July 2009 (UTC)[reply]
Truly - our OP has a clear conflict of interest here. You should simply not edit the article at all. If you feel your department is being misrepresented - or that there are factual errors - or that there is additional information that you have to offer - then please post it to the 'discussion' page associated with the article and let some other editor do the actual work of writing the article. Wikipedia's rules are reasonably tolerant of potential COI - but you really don't want to see news headlines "CDPHOPA caught editing the Wikipedia article about themselves!" - even if it is (strictly) within Wikipedias' rules - it gives a very bad impression. Better to feed information to independent editors - suggest changes WITH REFERENCES - and encourage people who do not have any affiliation to do the actual editing. SteveBaker (talk) 21:21, 7 July 2009 (UTC)[reply]
That's by no means a unanimous point of view. We want the articles to be right, and if an article is demonstrably wrong and can be corrected in an uncontroversial way, anybody should feel free to do it (that's my opinion, anyway). Looie496 (talk) 21:28, 7 July 2009 (UTC)[reply]
I'm not sure I disagree with you - it's just that the "uncontroversial way" is to place the relevent information (with references) in the Talk: page and let other editors do the editing. Allowing someone with a clear and obvious bias to edit the article is certainly not "uncontroversial". SteveBaker (talk) 03:04, 8 July 2009 (UTC)[reply]
Should I be afriad of using an aluminum garbage can? Will the heat from the hot plate react with the metal and release some unpleasant toxins into my ribs? —Preceding unsigned comment added by 199.166.14.239 (talk) 15:43, 7 July 2009 (UTC)[reply]
There are many aluminum grills. I personally don't use aluminum for grills, pots, pans, utensils, drinking cups, etc... I keep aluminum out of my house as much as possible. But, it isn't considered a health risk by the U.S. government to have an aluminum grill. -- kainaw™15:49, 7 July 2009 (UTC)[reply]
I believe the concern with aluminum is that it will leach into liquids it's in contact with, which isn't an issue here. People routinely cook stuff over a much higher heat wrapped in aluminum foil. I wouldn't give your trash can aluminum a second thought, and in fact that site has inspired me to build one of my own! --Sean16:28, 7 July 2009 (UTC)[reply]
My main concern would be about how hot the electric hot-plate might get. If it's hot enough to melt plastic insulation parts then it's possible that some piece of live circuitry might come in contact with the trashcan - making a serious electrocution hazard. The hotplate probably won't have been designed to operate in such close confinement without adequate airflow around it - so this is not so far-fetched. I would at least screw a nice chunky bolt to the side of the trash can and connect it up to the ground wire of the wall socket and to the metal case/frame of the hot-plate - that way if something untoward should happen, it'll trip your circuit-breaker. SteveBaker (talk) 16:50, 7 July 2009 (UTC)[reply]
The warning "Be sure to file down the edges so that the power cord can't get cut." in the article is inadequate because there is a real danger of electrocution. For safety install a feed-through grommet or similar where the cable passes through the metal wall. A wood plug with a hole for the cable can also be used. The cable should be clamped in some way so the connection to the hotplate is not stressed. Many cables are sheathed in PVC whose melting point is only 100-260 °C. Cuddlyable3 (talk) 20:20, 7 July 2009 (UTC)[reply]
Water in the bottom of the can can be a danger. The water might come from leaving the can outdoors in the rain, or condense from steam from damp wood chips or food. Cuddlyable3 (talk) 18:36, 8 July 2009 (UTC)[reply]
For what it's worth, my home-built electric smoker uses terra cotta pots rather than metal cans, as they're effective insulators (keeping the heat in the smoker rather than heating everything around). They're cheap, easy to find, and nicely circumvent the problem of potential toxins. (The pot, by the way, is the only design deviation. Get one that's made for plants and it'll even have a nice drain hole in the bottom, perfect for the hot plate's cord) — Lomn18:59, 7 July 2009 (UTC)[reply]
(This is actually the fourth time the question has been asked here at the ref-desk - plus once more on his/her user page. This user has edited Wikipedia only five times - and each time it's the same question.) We really don't have the first clue what's being asked here. All we're told in various earlier questions is that this is "light industry". But unless we know what these machines are, what the product is - and probably the answers to a whole bunch of other questions - there is no possible way to answer. SteveBaker (talk) 16:44, 7 July 2009 (UTC)[reply]
How far inland (in miles)could a 80 to 90 ft wave travel along the Florida coast assuming that highest elevations stay between 30 and 40 ft above seal level? Is there some kind of formula for figuring
something like this out?209.26.182.3 (talk) 17:47, 7 July 2009 (UTC)[reply]
The Cumbre Vieja article contains numbers for waves "30 to 60 m", for which it says "inundate up to 25 kilometres (16 mi) inland. This would greatly damage or destroy cities along the entire North American eastern seaboard. The physical damage would take tens if not hundreds years to repair and restore. The economies of the countries affected would likewise take several years to return to the pre-inundation levels." That's assuming you mean 90ft (roughly that lower 30m number) as the wave height in the open ocean - when the seafloor forces the wave to surge to much greater heights. Calculating the damage area for a given wave would require a pretty sophisticated fluid-dynamic model of the area, as the wave's energy is spent when interacting with the seafloor, foreshore, and the land, and so the shape and composition of each will be a major factor. Plus the level of tide that pertains when the wave arrives will significantly affect it. 87.113.26.43 (talk) 18:54, 7 July 2009 (UTC)[reply]
Your statement that the wave is higher in the open ocean is blatantly false; tsunamis are at their highest near the shore while breaking (see tsunami). You are right though in saying that it would require sophisticated computer modeling; however, it would surely be only a few miles, maybe a few dozen, as the wave's energy is dissipated very quickly. The article cited above states that a 30-60 m open-ocean wave would be a few hundred meters high at impact with the shore, but still only penetrate 25 kilometres (16 mi) inland. For an everyday world analogy, just look at waves over a sand bar; they can start 10 feet high, but be only about 1 foot or less after passing over a sand bar only a few inches above sea level. -RunningOnBrains(talk page)19:00, 8 July 2009 (UTC)[reply]
If we are talking Florida that could still seriously mess things up. Most big cities are near the coast (although depending on what side of the pan-handle the tsunami is going to hit) The bigger problem is that the fresh water (not salt water) supply would be impaired or wiped out and the Everglades might have to be written off entirely. 71.236.26.74 (talk) 09:38, 9 July 2009 (UTC)[reply]
I tend to favour the "criticisms" area of the Cumbre Vieja article in any case; other mega-tsunamis have been birthed before and have all failed to cross oceans with the kind of destruction those guys are postulating. It will be no day at the beach (literally!), but some of their figures are right off the chart. Matt Deres (talk) 03:01, 11 July 2009 (UTC)[reply]
Depression and violence
Is there any link between the two? I mean, someone who is depressed has the feeling of not being in control of his life, violence could be a way of being in power.--88.1.123.111 (talk) 17:58, 7 July 2009 (UTC)[reply]
Depression is sometimes associated with manic-depression, however, even in this case and in the case of other mental illnesses, the sufferes are seldom violent. --Quest09 (talk) 18:09, 7 July 2009 (UTC)[reply]
Violence as a result of learned behaviour or as a symptom of extreme emotion can be exhibited by people of all backgrounds and of all mental and physical states. As far as I know, there is no specific link between depression and violence, unless one wishes to speculate that those who are depressed are more likely to be, or have learned to be, violent. I don't see a correlation though. Maedin\talk18:24, 7 July 2009 (UTC)[reply]
Depression is most commonly associated with passivity but "agitated depression" can sometimes be associated with violence, even of a horrific kind. Looie496 (talk) 21:22, 7 July 2009 (UTC)[reply]
I don’t know about depression specifically, but in general, mental illness is a fairly weak predictor of violence. Stronger predictors of violence include being young, being male, having a past history of violence, and substance abuse (alcohol and/or drug). Although not mentioned in my reference, I’ve also read that having been a victim of violence is a stronger predictor of being violent than having a mental illness. The mentally ill who do tend to be violent are typically schizophrenics who are not taking their medication.[29]Red Act (talk) 21:33, 7 July 2009 (UTC)[reply]
As a follow-up, here[30] is a reference for being a victim of violence, and witnessing violence also being good predictors of being violent. Note that the correlation between depression and violence is complicated by there also being a correlation between depression and other predictors of being violent, such as having been a victim of sexual or physical abuse, having witnessed violence, or substance abuse by a family member. Red Act (talk) 21:56, 7 July 2009 (UTC)[reply]
Yeah, to emphasize the above (I already started writing)—the abstract of this epidemiological study states that they were unable to come up with a causal link leading from mental illness (in general) to violence—but that subjects with mental illness "did report violence more often, largely because they showed other factors associated with violence." It's not an answer to your question, but it does help explain why your question is difficult to answer. There are a great deal of confounding variables involved. For example, a depressive may be more likely to self-medicate with a psychoactive substance that IS related to violence. Or a depressive may owe their mental illness partially to a violent background. Furthermore, clinical depression itself is kind of tricky to define—especially in the milder cases where it can begin to blend into normal behavior. Good studies on the link you're proposing are difficult to construct. Alfonse Stompanato (talk) 22:05, 7 July 2009 (UTC)[reply]
In this seminal 1963 paper, Dr. John MacDonald found that people who threaten to perform violence are likely to actually perform violence. This seems to be one of the best predictors. Unfortunately, the sample population for this study was not representative of the larger population, but there are numerous followup studies. Nimur (talk) 14:28, 8 July 2009 (UTC)
John MacDonald had a farm, E-I-E-I-O... ;-)
76.21.37.87 (talk) 08:56, 9 July 2009 (UTC)[reply]
Human Body Responses
I thought I read somewhere that an experiment was conducted in which women listened to tapes of babies crying and their chest size grew over a period of time. Can anyone point me to a Wiki article about this body response?
Also, I think in the same article, it suggested that when men are in close proximity of women, but not seeing them, but smelling "female pheromones", their pupils automatically dilate and that their irises can actually change color. Does anyone know the validity of such claim? --Reticuli88 (talk) 19:43, 7 July 2009 (UTC)[reply]
I think the validity of these claims is nonexistent. The first thing sounds like a fairy tale: I want my breast to grow to feed the baby, so my breast will grow. That is not the way that the growing of breasts, for example during pregnancy, is controlled. This is hormon-based. Another problem with this statement: How long should these "victims" have listened to the crying babies? For weeks? What were the appropriate controls? Did they even have controls (like woman listening to various other sounds for the same time)? Because of these problems I do not believe that such a study was performed in a well-controlled, scientific manner, if it was performed at all. The existence of human pheromones was never demonstrated under strict experimental conditions, all papers I have seen that show effects have methodological flaws or cannot be reproduced. Next, the human iris cannot spontaneously change color. The color is determined by the structural anatomy of the iris, and this can only change very slowly (in days to months, if you are seriously ill, for example). What can change is the perceived color determined by a subjective observer, depending on the mood and light of a situation. But these would not be parameters that a scientific paper could use, because they are not objective. And the setup you describe is very vague: by "not seeing them", do you mean, they didn't know at all if a woman was nearby? Or was this just being blindfolded, and being touched by a woman? In this situation I would expect their pupils to dilate, because they would get excited, and the reason would not be pheromones :-) Even knowing, without being touched, that someone is coming closer, could lead to a "stress"-response, which also encompasses pupil dilation. --TheMaster17 (talk) 12:25, 8 July 2009 (UTC)[reply]
I'm not familiar with any of those claims. The closest I've seen was some original research that crying babies cause even unrelated nursing women to intensely lactate (also, see here). No real surprise there; the effect is a little like your tummy grumbling when you smell something good to eat (only in reverse!). The idea that crying babies could simply make someone's boobs bigger could possibly be related to that phenomena, as breasts do get larger as they engorge with milk. The eye dilation thing reminds me of something I read in Desmond Morris' Manwatching book, to wit: that when presented with a picture of a baby, women's pupils tended to dilate, and so did the pupils of fathers, but not the pupils of childless men. He also discussed other instances of differential pupil dilation, but I don't recall what they were offhand. Matt Deres (talk) 01:34, 9 July 2009 (UTC)[reply]
Do cations and anions of a same molecule have different Lewis structures?
I've had to write out the Lewis structure of SiH4, PH3 , NH4+ and H2S. I've just finished the exercise, and I was wondering if the Lewis formula for ammonium would be different if it was an anion (or a neutral molecule) instead of a cation.
In principle, you could add two electrons to an ammonium cation and get an anion:
NH4+ + 2e− → NH4−
However, doing so would probably cause the molecule to decompose, as the electrons would enter N-H σ*antibondingmolecular orbitals and either break two or weaken four N-H bonds.
TO reply more directly; absolutely. The charge on an ion is due to the number of electrons on it. Insofar as changing the charge makes a change to the number of electrons, it would also change the number of "dots" you add to a lewis structure. For a real example of two structures which REALLY EXIST but only differ by charge, consider Sulfur trioxide and the sulfite ion. --Jayron32.talk.contribs23:16, 7 July 2009 (UTC)[reply]
Here's the Lewis structure of the ammonium cation, NH4+: http://www.benjamin-mills.com/Wikipedia/ammonium-cation-Lewis-structure.png. You want to add an electron to this structure. The usual school chemistry answer is that you can't – nitrogen has a full outer shell of eight electrons and has no room for any more. Likewise, each hydrogen has a full outer shell of two electrons and cannot accept any more.
I calculated the structures of the NH4+ cation and the NH4· radical in Spartan (using the MP2 method) and got N-H bond lengths of 1.025 Å for the cation and 1.039 Å for the radical. I also calculated that the extra electron added to NH4+ goes into an electron cloud spread over the whole molecule, that looks a bit like this.
So within the confines of traditional Lewis structures and school-level theories of chemical bonding, you cannot add an electron to NH4+.
But if you insisted on drawing a Lewis structure for the NH4 molecule (which does exist), it might look a little like this
No. They may emit more co2, but they're not introducing new carbon into the ecosystem. It all comes from materials they've eaten.
Compare that to digging up carbon in oil or coal that has been dormant and sealed off since dinosaurs walked the earth. APL (talk) 22:12, 7 July 2009 (UTC)[reply]
Yes. Firstly for transportation (be it air, rail, or road) a heavier person requires more energy to move them; if that energy comes from a fossil source, there's more fossil carbon released. Secondly for food; modern industrialised food production makes heavy use of fossil fuels, to plant, fertilise, pest-protect, harvest, transport, and process. The more food one eats, the greater the fossil carbon for which one is responsible. Naturally, while the redacted question presumably discussed the morbidly obese, the same is true for all heavy people, including the freakishly tall and the uncannily dense. In practice, though, do these really amount to a worthwhile amount? And does the extra bother of collecting a new weight-specific tax cost more (in both money and CO2) than it saves? Probably not. Anyway, the morbidly obese die younger (often of sudden, agonising cardiac failure), saving the carbon economy the burden of manufacturing the slippers and warming the cocoa of the selfishly thin. 87.113.26.43 (talk) 22:40, 7 July 2009 (UTC)[reply]
Note that the production, transport etc would usually already be taxed if you have a fair carbon tax. Note also a person's size is only likely to be a minor contribution to their carbon footprint. A 200kg person who sits on the couch in their tiny house all day watching some low powered (e.g. 17 inch) LCD TV with no heater or ac and eats crappy food (whatever is cheapest) will likely have a much smaller carbon foot print then someone who drives to gym every day (with their gaz guzzling sports car), and has a very active social life (driving every where of course), watching stuff on their 100 inch plasma when they're at their 1000 square metre home which is always at a perfect temperature; and regularly takes holidays in distant locations and eats only the finest food, e.g. lobster air flown from remote locations with expensive spices that are difficult to collect and again come from remote locations and drinks expensive wines and bottled water. Nil Einne (talk) 00:21, 8 July 2009 (UTC)[reply]
I have restored the question. The post comes from somewhat of a known troll, so if the question is removed entirely I won't object. But it's a legitimate question. Poorly parphrasing it and leaving it here to be answered is bad form. APL (talk) 23:39, 7 July 2009 (UTC)[reply]
Yes. What a person eats has a major impact on their carbon footprint. According to Livestock's Long Shadow, a United Nations report, the greenhouse gasses due to livestock production in the U.S. amounts to more than that of all transportation in the U.S., combined. An obese person who eats twice as much of everything as if they just ate enough to maintain a healthy body weight is doing more damage to the environment than if they were to double how many miles they drive in a year. Or looking at it from a positive perspective, that same obese person changing to eat just enough to maintain a healthy body weight would have a bigger positive impact on the environment than if they completely gave up their car and just walked everywhere. See also Low carbon diet. Red Act (talk) 02:04, 8 July 2009 (UTC)[reply]
I should probably have also stated that the hypothetical person was average height, eating an average American diet, and burning an average number of calories when at a healthy weight. And by “environment”, I of course am just referring specifically to global warming. Red Act (talk) 03:09, 8 July 2009 (UTC)[reply]
Actually, the reverse is the case. While the person is young and growing, they consume more carbon than they emit...the remainder going to build up the body. As adults, we all consume carbon and emit carbon in roughly equal quantities. But when we die - all of that carbon we stored up in our youth is still inside the corpse. If one were to be cremated - then exactly 100% all of the carbon you consumed and failed to exhale over your lifetime will be turned into CO2 for a zero total carbon impact. But if one were buried - then that carbon is locked away underground. So overall, fatter people who opt to be buried and not cremated have locked away slightly more carbon into the ground than they consumed. Ha! Eat that troll! (Of course, all of this is totally negligable compared to all of the other carbon impact a particular human has on the planet - so the information above is just as useless as the OP's original assertion). SteveBaker (talk) 03:00, 8 July 2009 (UTC)[reply]
Well then, why not eat them? Not a lot of meat, I'd imagine, but get a few dozen together and the right spices, and it sounds like a fine dinner. --Jayron32.talk.contribs04:33, 8 July 2009 (UTC)[reply]
I would actually very much like to try what a well-prepared paddy mouse dish tastes like. From personal experience, a platter of frog legs is a fine dinner to say the least, miniature size of the said legs notwithstanding. Never tried a roasted rodent, though. Do you know of any Vietnamese restaurants in US or in Western Europe that serve a paddy mouse dish? --Dr Dima (talk) 07:59, 8 July 2009 (UTC)[reply]
Do birds have an equivalent to the navel, as seen in mammals?
In mammals, the navel/bellybutton is the point at which the umbilical cord was attached while in the womb. Is there something similar in birds, i.e. at the point at which the bird was connected to the yolk, while in the egg? I've seen cross-sectional pictures of fertilized eggs and it looks as though the bird foetus is connected to the outside of the yolk by something similar to an umbilical cord. --84.69.51.112 (talk) 01:12, 8 July 2009 (UTC)[reply]
No. Not even all mammals have them. We are a part of the "Placental Mammal" sub-group - the umbilical cord connects to the placenta. No placenta - no cord. Hence, Duck billed platipus and Kangaroos don't have belly buttons because, while they are mammals, they are not placental mammals. Birds lay complicated eggs with all sorts of membranes and stuff in them - but I don't think there is a similar connection. See image at right of a 1 week old chick embryo - I don't see any kind of cord there... SteveBaker (talk) 02:48, 8 July 2009 (UTC)[reply]
Just read an article in my local newspaper about a policeman suffering a dislocated knuckle while attempting to arrest someone. I've never heard of such an injury before; is it very common? Joint dislocation makes me guess that it's not the same as any of the dislocated finger pictures (can't remember which joint is the knuckle, and our article is very poor quality, but I expect that these would also be captioned "dislocated knuckle" if it were the same thing), so I'm assuming that this is not a dislocated finger. Nyttend (talk) 02:09, 8 July 2009 (UTC)[reply]
Knuckle is a common term for the any of the three joints on each of your fingers (well, two on your thumb). A dislocated knuckle is identical to a dislocated finger. The two bones that meet at one of the knuckle joints can become disarticulated just as any other joint can. --Jayron32.talk.contribs02:31, 8 July 2009 (UTC)[reply]
Animal intelligence and attempts to escape captivity
Is there any evidence on whether more intelligent animals in captivity are more or less likely to attempt to escape? NeonMerlin02:12, 8 July 2009 (UTC)[reply]
Depends how you define intelligence. A hamster is more likely to escape than a dolphin; can you claim that the hamster is more intelligent? A male cat with its balls still attached is more likely to attempt to escape than a neutered one; does the feline intelligence reside in the scrotum? I don't think so... --Dr Dima (talk) 04:00, 8 July 2009 (UTC)[reply]
The females of the human species thinks that their male counterpart do think with their scrotum and its attached part. :)--Lenticel(talk)04:22, 8 July 2009 (UTC)[reply]
Well, monkeys will escape if given the slightest opportunity, and they're the most intelligent animals in captivity, so at some level it is true. Looie496 (talk) 05:53, 8 July 2009 (UTC)[reply]
I would say that monkeys/chimps are escaping not to necessarily escape, but out of curiosity of the unknown. I know my pet budgerigars are kept captive in a cage and they like it. Whenever I remove them from the cage, they always try to fly back into it. This must be because they know that the cage provides security and necessities for their survival. This would be untrue for a captive wild bird rather than birds that were born in the cage. -- penubag (talk) 10:27, 8 July 2009 (UTC)[reply]
Parrots are fairly notorious for figuring out how to escape from their cages - routinely pulling back bolts, undoing clasps, lifting up sliding panels, butting open hatches, etc. I've personally seen a cockatoo that understood how to open a padlock by turning the key (the cage was actually padlocked to prevent the bird from getting out - the owner left the key in, figuring that she would *never* work that one out!). Budgies, whilst not as intelligent as Macaws, Amazons, African Greys, Cockatoos, etc. do sometimes work out how to get the door open - though it seems to very from individual to individual. Some never appear to consider trying to escape - though I suppose that it may just mean that those particular birds are quite happy to remain in the cage. --Kurt Shaped Box (talk) 10:52, 8 July 2009 (UTC)[reply]
Does John Dillinger count as an "intelligent animal?" He made some impressive escapes. Our hamster lifted up the water bottle out of its niche in the seemingly secure Habitrail, escaped, found some colored tissue paper, tore off a 2 foot by 1/2 inch strip of white, and a similar strip of pink, took them back into the cage, and up to his bedroom chamber, where he installed them as decorations. Perhaps the most intelligent animals escape, go shopping, and come back. If they had internet and a credit card, would they just order stuff to be delivered? 24.13.87.201 (talk) 15:00, 8 July 2009 (UTC)[reply]
According to our article on Spin (physics), photons have a spin and are massless. In fact, the same article notes that the only spinless particle in the Standard Model is the Higgs boson, which if it exists, definately has a mass. So, to answer your question, all particles in the standard model, even those which are massless, and even those which are point particles and lack internal structure or even volume, have spin, except for the Higgs, which has a mass but no spin. Of course, if it turns out that the Higgs does not exist, then the answer would be that all particles have a spin. --Jayron32.talk.contribs05:04, 8 July 2009 (UTC)[reply]
I want to know if it is possible for a massless particle to have no spin, not just whether one exists. For example, it is impossible for a massless particle to have a speed lower than c, not because no massless particle with this ability is in the standard model, but because of special relativity. Does something similar rule out spin 0 massless particles, or are they theoretically possible? 76.67.78.167 (talk) 07:45, 8 July 2009 (UTC)[reply]
In today's quantum mechanics there is no rule forbidding the existence of spin 0 massless particles. In fact if you google the term "massless spin-zero" you will find several papers that either propose such particles or ways to detect them, should they exist.
But if it one day turns out that no massless spin-zero particles exist, there will hopefully be a theory explaining why it's impossible. EverGreg (talk) 08:03, 8 July 2009 (UTC)[reply]
I have a question that is (sorta-kinda) related to the question "Black or white parasol" in the science reference desk archives. This has to do with the paint job on the Lockheed SR-71 vs. that on the Concorde. You see, the SR-71 is painted a flat black (that's why they call it the Blackbird), while the Concorde is painted a glossy white. I was just wondering, which is a better choice for dissipating the heat generated by air friction and such during supersonic flight? Thanks, and clear skies to y'all!
76.21.37.87 (talk) 06:03, 8 July 2009 (UTC)[reply]
I'm not sure about the heat-reflective differences, but my understanding is that the reason the Blackbird is painted black is to help it hide from Radar. At least that's what I heard on some tv show. According to this (http://answers.yahoo.com/question/index?qid=20080604155845AA2TCgt) Yahoo answers the colour white is used to help facilitate ground-checks (though to be honest there's no more detail on how white iteslf helps do this) ny156uk (talk) 07:22, 8 July 2009 (UTC)[reply]
There could be a simple explanation. At [31] it says: White colors are much easier to cover with final topcoats. That is, it's easier to paint a logo or some pattern on the aircraft if you do it on a white background. When it comes to military crafts, the stealth aircraft article notes that F-22 was designed to be less visible to the naked eye. I guess dark colours play a part in that. EverGreg (talk) 07:49, 8 July 2009 (UTC)[reply]
The SR-71's black paint was selected primarily for its radar absorption properties. Stories about the thermal effects of the paint may have been injected as intentional misinformation to draw attention away from the "stealth" radar characteristics. It's worth noting that most of the useful stealthy characteristics come from the shape of the airframe, the engines, and the (minimal use of detectable) onboard electronics - so even the radar dissipating paint is itself sort of a red herring. Nimur (talk) 14:03, 8 July 2009 (UTC)[reply]
A physicist once told me that a steam radiator painted black would emit heat more efficiently than one painted white or silver. The SR-71 gets very hot from friction with the air at extreme speed. Would the black paint allow the heat to be radiated out better than a silver or white finish? Edison (talk) 15:35, 8 July 2009 (UTC)[reply]
Thanks, Edison and Dragonsflight, you really answered my question from a physics point of view (BTW, my physics textbook also confirms that black paint radiates heat better). Now just one final point, it says in The Lore of Flight that the Concorde's white paint "reduces the temperature of certain areas [of the plane's airframe] by more than 10 degrees Centigrade", is that book just wrong about it, or are there some other heating effects (in the case of the Concorde but not the Blackbird) that are better countered by white paint? Thanks, and clear skies!
76.21.37.87 (talk) 09:26, 9 July 2009 (UTC)[reply]
Torque multiplication in a torque converter
How does it actually happen ? I fail to accept the explanation according to which the redirected oil flow (done by the stator) entering the impeller would do the trick, because it would only relieve the load on the engine and not transfer more force to the transmission.
My own guess is that there must be some kind of reaction force acting on the turbine in a similar manner as in a fire hose when the hose is opened at a close proximity to a solid wall.
See Torque converter for more on this and it and the article has a link to howstuffworks. An interesting sort of related topic is torque amplifiers which I've made a couple of, they are used in power steering for instance. Dmcq (talk) 10:10, 8 July 2009 (UTC)[reply]
To quote the howstuffworks article: Modern torque converters can multiply the torque of the engine by two to three times. This effect only happens when the engine is turning much faster than the transmission. —Preceding unsigned comment added by EverGreg (talk • contribs) 10:14, 8 July 2009 (UTC)[reply]
Remember that a fluid coupling is a torus - there are two types of fluid flow
Going around the torus (ie like a wheel)
Going around the circular segments of the torus (ie going around the circular cross sections)
It's the first that transfers the torque in a fluid coupling).
In a simple torque converter the stator redirects the second flow (using angled blades) so that some of its motion is converted to the first type of flow. (The turbine blades can also be angled, but it's unnecessary to imagine this for a simple explanation)
OF COURSE there is a reaction of the liquid flow on the output stage - this is how all fluid couplings and torque converters work fundamentally. ie if you point a fire hose at a shovel the shovel will be forced back by the water.
I live in dry southern california, it's practically desert. A few times, I've traveled to other countries with much more humidity than where I normally live and notice that my hair (as well as my other family members) has grown faster during the time I've spent in this country. I don't know if I'm just imagining things or if humidity really does affect the speed of hair growth. On a related note, after removing a cast after a broken bone has healed will reveal that the hair on the skin below has grown considerably longer. Can this also be related to the dampness of the skin under the cast? -- penubag (talk) 10:21, 8 July 2009 (UTC)[reply]
This is a fun thing to notice! :-) Hair actually expands in moist conditions and contract in dry ones. I've seen 3% being cited as a figure. If your hair is 30cm long, that should make for a difference in almost 1cm. This has been the basis for some hygrometers, which measure the humidity in air. EverGreg (talk) 10:36, 8 July 2009 (UTC)[reply]
Hmm, that is really interesting, perhaps that's what happens when I travel! But it doesn't answer my second question as to why hair grows long and dark under a cast.-- penubag (talk) 11:02, 8 July 2009 (UTC)[reply]
No it dosn't. Though I suspect that if it seems dark, that's because it's in stronger contrast to the skin, which is paler after being covered in a cast. That it looks longer may be an optical illusion from the increased contrast. The hair on a stubbled chin is more prominent if it's black for instance. EverGreg (talk) 11:10, 8 July 2009 (UTC)[reply]
Nope, I guess you've never worn a cast (lucky you). It grows substantially longer while under the cast thus darkening as most longer pieces of hair do. -- penubag (talk) 11:24, 8 July 2009 (UTC)[reply]
I suspect the difference is not in growths, but in life time. The cast protects the hair, so it will not fall out or break of as fast as on the unprotected skin. So you will have more and longer hairs, although none grows faster. --Stephan Schulz (talk) 14:21, 8 July 2009 (UTC)[reply]
The darker color might be due to it not being exposed to the bleaching effects of the sun. Grey hair has recently been identified as being caused by hydrogen peroxide accumulating in the hair. I don't know if it requires light to bleach hair, but that may also happen. 71.236.26.74 (talk) 15:27, 8 July 2009 (UTC)[reply]
Sunlight can certainly lighten hair. When a small boy I went (from the UK) to live in the much sunnier Far East for a few years; my normally dark blond/light brown hair turned very light blond for that period, but re-darkened on returning to Blighty. 87.81.230.195 (talk) 20:18, 8 July 2009 (UTC)[reply]
I find it difficult to understand what you mean. Do you want to know what happens if you mix Calciumhydroxide with Glycerine (as the Title suggests) or what happenes if you mix it with Water (as the Text suggests). To find out about the pH of the resulting Mixture you simply need the pKs-Value/ pKa-Value of the Substance in question. In your case I just found the one of ethylene glycol, which already is 14.2 so considering the chemical relation between the two substances I would guess there is no big change in pH of the water whatsoever as glycerine should not be that easy to deprotonate. And of you mix it with a base you would either find that nothing happened, or you might create an Adduct depending on base strength. --91.6.6.157 (talk) 16:55, 8 July 2009 (UTC)[reply]
Particles that are their own antiparticles and vice versa
It appears that it IS its own antiparticle, and "self-anihilates" all on its own. The quark structure of the pi-0 particle is listed in the article, which would also seem to indicate that it is clearly its own anti-particle. As with all aspects of quantum physics, try to suspend basic logic and reason when understanding how the system works. There are two possibilities here; either neutral pions do not exist, or your own understanding of the matter/antimatter interaction is flawed. Perhaps there is something in the pi-0 structure which makes it metastable; that is it probably doesn't exist for long, but it hangs around just long enough to prove that it exists. --Jayron32.talk.contribs12:49, 8 July 2009 (UTC)[reply]
Things are simpler than Jayron32 presents them. A neutral pion consists of one quark and one anti-quark. It is therefore a composite of matter and antimatter and can annihilate itself. To dig deeper, the first thing to grasp onto here is the conservation laws. For instance the Charge conservation or more to the point, Baryon number conservation. The baryon number is the number of quarks minus the number of antiquarks divided by 3, so it's zero for the pion. Zero means it can evolve into something with zero quarks without breaking baryon number conservation. For the neutral pion the sum of the electric charge of the quarks sum to zero, so it's also ok to transform into something with no charge. (In fact, it couldn't be its own antiparticle if it had a nonzero charge, because particles and antiparticles have oppsite charges) In total, this means that the pion is allowed to transform into pure energy, or two photons to be precise:
It can however also transform into an electron and a positron since these too consists of no quarks and their electric charges sum to zero. Another particle which is its own antiparticle is the Z0 boson. Not surprisingly, this also has the ability to turn into photons, or pure energy:
To be super-precise, an antiparticle has the opposite charge of its corresponding particle. When you have zero charge, you can therefore be your own antiparticle :-) EverGreg (talk) 13:31, 8 July 2009 (UTC)[reply]
Thanks guys, that clarifies it a bit. :) Especially "It is therefore a composite of matter and antimatter and can annihilate itself.".
I'm still confused about the whole pion as a strong force carrier, though. Particle physics is a very weird field. Are those pions there all the time (and add to the mass?!), or are they virtual, or what? :) -- Aeluwas (talk) 15:13, 8 July 2009 (UTC)[reply]
It seems as if the article about virtual particle semi-answers that question... not that I can say that I understand that it works. ;) -- Aeluwas (talk) 15:15, 8 July 2009 (UTC)[reply]
That is actually a confusing topic! Nobel prize winner Yukawa thought that the strong force was transmitted via pions. It is actually transmitted via gluons, but gluons can turn into quark-antiquark pairs, which is what pions are. These pions can in turn back into gluons. These constitute the sea quarks. So it's not completely wrong to say that the pion is involved. Yukawa's pion model has also been retained in nuclear physics as an approximaiton because it has been mathematically difficult to work with gluons alone, or so I've heard. EverGreg (talk) 18:31, 8 July 2009 (UTC)[reply]
EverGreg, There is nothing wrong with saying that pions transmit the strong force between the protons and neutrons inside a nucleus the same way that there is nothing wrong with saying that the nucleus is made of protons and neutrons. In fact, whenever dealing with sacales larger than the size of the nucleons, due to color confinement, the strong force is constrained to being transmitted by color singlets (white, if you will) which cannot be satisfyed by single gluons. The lightest color siglet particles are the pions and that's why they are indeed the most important component of the interaction between nucleons. Dauto (talk) 22:15, 9 July 2009 (UTC)[reply]
is there a direct correlation between price of agricultural product and growing time of its tree/plant? What are the most expensive agricultural products?--Quest09 (talk) 17:50, 8 July 2009 (UTC)[reply]
Saffron is one of the most expensive agricultural products—it's the most expensive spice by weight. I wonder if there are any pharmaceuticals that are derived from plants in tiny, expensive quantities? -- Coneslayer (talk) 17:56, 8 July 2009 (UTC)[reply]
Marijuana is a rather expensive agricultural product, and it is very fast growing. I think that the fact of it being illegal is the primary impact on its high price. I don't know how long it takes to grow the plants for cocaine. 65.121.141.34 (talk) 18:11, 8 July 2009 (UTC)[reply]
One would naively expect that the slower the plant grows, or the longer it takes to reach maturity, the more expensive would be its fruit (or, generally, any product obtained from it). That is true in some cases (walnuts, for example), but not in general. Prices are set by supply and demand, and the rate of the plant growth is just one of many factors. Some other factors that play a role are: 1. Desirability of the product (compare good Burgundy wine to cheap local one); 2. Legality of the product (see above); 3. Yield (roses are rather fast growing, but rose oil is very expensive nevertheless); 4. Ease of cultivation (e.g. truffles and brazil nuts). And there are more factors, of course. --Dr Dima (talk) 19:10, 8 July 2009 (UTC)[reply]
Perishability is a big one. Raspberries grow like weeds in my part of the world, yet they cost about US$16/lb for moldy ones at the grocer. --Sean23:25, 8 July 2009 (UTC)[reply]
Some essential oils are amazingly expensive. This site claims that 7 tonnes of lemon balm are needed to produce 1 kilogramme of Melissa essential oil. [32] This site sells 1 kilogramme of Melissa essential oil for £1,800! [33] Some of the absolutes are even more expensive: 1kg of lotus (plant) absolute costs £5,900!--TammyMoet (talk) 19:26, 8 July 2009 (UTC)[reply]
The caveat in this analysis is that many of the incredibly expensive (per pure unit) things are used in only minute quantities (50 g leaves for melissa-based therapy at £1,800/7 tonne oil equivalent?), so the cost-per-enduser-product isn't so bad. Same pattern holds for API for pharmaceuticals...manufacturing price-per-truckload of the active ingredient might look huge but at only a few mg per dose the dose cost is reasonable. DMacks (talk) 21:07, 8 July 2009 (UTC)[reply]
Truffle (fungi)s can sell for a fortune. According to the article the record for a white-truffle was £165,000 for one that weighed 1.5kg. 22:37, 8 July 2009 (UTC)
banana plants take a long time to grow and only bear fruit once and then die off. They are a third world country product, though and economic pressures keep the price low. Some rain forest timber takes decades to grow but it doesn't fetch a fair price because it's not a "standard" species like oak or redwood. So world economy plays a role in pricing. 71.236.26.74 (talk) 04:50, 9 July 2009 (UTC)[reply]
"Some rain forest timber takes decades to grow but it doesn't fetch a fair price because it's not a "standard" species..." -- And what do you define as a "fair" price?
Better than what it's fetching now at least. It is generally valued at less than "standard hardwoods" because consumers are not familiar with the names, etc. If you want to start a discussion on there not really being a "fair" price for cutting down a tree from a rainforest I don't think this is the place (but I happen to agree). 71.236.26.74 (talk) 14:40, 9 July 2009 (UTC)[reply]
The amount of time that a certain crop is in the field would be a factor in its price because of the opportunity cost of said crop taking up the space when another one, possibly faster growing, could be planted instead. —Preceding unsigned comment added by Frogmaster3950 (talk • contribs) 15:37, 10 July 2009 (UTC)[reply]
anchors and tides
If you have a boat and drop an anchor, and the tide goes up a lot, like 20+', will the anchor sink the boat if the anchor line was pretty taut at low tide? 65.121.141.34 (talk) 18:54, 8 July 2009 (UTC)[reply]
Only if the anchor weighed so much that it pulled the top of the ship's hull below the waterline - and that won't be the case, because the ship wouldn't ever be able to lift and carry its own anchor. Anchors don't rely on their mass (mostly), but on hooks or plates to catch the seabed; the weight of a heavy anchor is there only to help it bite into the seabed better. 87.113.26.43 (talk) 19:02, 8 July 2009 (UTC)[reply]
Well, it's possible that the anchor could get wedged under something really heavy and get stuck. However, even then, the anchor line/chain is likely to break before the boat could go under. As a practical matter, this is never an issue. Even with an all-chain anchor, good boating practice is to lay out enough chain to give a scope of about 7:1 -- translated, for every one foot of depth, you should have seven feet of anchor chain in the water. In adverse conditions, even more should be laid out. Consequently, you've always got far more chain in the water than the tide could impact. — Lomn19:29, 8 July 2009 (UTC)[reply]
I've seen the opposite of that happen though - someone tied their boat to a jetty and the tide went out - initially lifting the boat out of the water - then ripping the fixtures that the ropes were tied to off of the deck - then finally allowing the boat to float away. SteveBaker (talk) 20:25, 8 July 2009 (UTC)[reply]
If an anchor chain is pulled to a vertical position by a rising tide, further rise of the water will pull the anchor free. In case any reader is a land lubber and does not know how anchors work, an anchor has a crossbar at the top, or in the case of a patent anchor it has flukes which are hinged at the bottom. Immediately after the anchor is dropped, the ship drifts a bit due to current or wind. The crossbar causes one of the flukes to be at an angle to the bottom. The drift causes the fluke to dig into the bottom (unless the bottom is rocky). Further drift causes the fluke to dig deeper until the ship is brought to a standstill. Obviously, the ship does not have to drift far for this to happen. In the case of a patent anchor, both flukes initially lie flat on the bottom. As the ship drifts, the weight of the flukes causes them to dig into the bottom. With either type of anchor, if the chain becomes vertical, further pull on the chain will lever the anchor out of the bottom (unless a fluke is hooked under a rock, as another poster pointed out.) The bottom is relatively soft – it had to be for a fluke to dig in. So the anchor can be levered out of the bottom. When pulled vertically, I don't think the chain is likely to break – it held the ship against drifting so it is not badly flawed. The Wikipedia article for "anchor" is very poor. Also, the anchor shown in the illustrative photo seems to be without the essential crossbar. GlowWorm. —Preceding unsigned comment added by 98.21.111.233 (talk) 01:04, 9 July 2009 (UTC)[reply]
Or maybe the anchor didn't have a crossbar. - GlowWorm.
On a practical front, sailors are taught to use a length of anchor rode (the technical word for the chains and ropes) between five and seven times the depth of the water, AND to take account of tide changes in the calculation. Most anchors will drag if the rode is much shorter than this. DJ Clayworth (talk) 18:23, 10 July 2009 (UTC)[reply]
B vitamins
NZ is currently planning to begin mandatory folic acid (vitamin B9) fortification of most bread. This has lead to a lot of debate and one of the issues which people have been saying on forums is that if you increase consumption of one B vitamin you need to increase them all or you risk deficiencies in the other B vitamins. This seemed strange to me and reviewing further I can't find any evidence of this being true. From what I can tell, the only currently known risk is between folic acid and vitamin B12. Specifically since the effects of these two are connected, taking extra folic acid may mask some of the symptoms of vitamin B12 deficiency (but it doesn't treat all the problems) so that it's not so obvious the person is suffering from it (it doesn't require you increase your vitamin B12 intake if it's sufficient). The evidence for this being a problem in the US and Canada who also have fortification however appears limited. There is also some more recent suggestion that a high folic acid intake and a low B12 may be bad and excess folic acid consumption "worsens the effects of B12 deficiency and in fact may affect the absorption of B12" (although I suspect this is talking about very high levels that your rather unlikely to get from fortified bread anyway). In particular, there's little evidence if you have a healthy/sufficient B12 intake, taking extra B9 suddenly requires you to increase B12 intake or any other of the B vitamins. Is there something I've missed or am I right that the claims about needing to increase all B vitamins are unsupported? Nil Einne (talk) 21:24, 8 July 2009 (UTC)[reply]
Yes that and the Vitamin B article (as well as a quick Google) neither of which provide any real support for the notion other then what I mentioned. I normally would have dismissed the comments as 'ill-informed' (the place I read them isn't known for the high standard of debate [35]) but decided to check since more then one person made the claim. I presume they're confused by the B9-B12 issues as well as perhaps the general advice it's not wise to take excess of any vitamin and the general belief that improving one's diet and better food is better then supplements and fortification. Nil Einne (talk) 01:01, 9 July 2009 (UTC)[reply]
Ctenophores as human food source
It's frequently been suggested that we could adopt jellyfish as a food source once fish stocks are depleted, but could we do the same with ctenophores? Are they common and nutritious enough to make this idea viable? 69.224.113.202 (talk) 23:18, 8 July 2009 (UTC)[reply]
Jellyfish do contain nourishment. They are one of the food items of the ocean sunfish. Sadly, some of the sunfish are killed by swallowing one of those thin plastic bags, thinking it to be a jellyfish. Like other human castoff material, those bags even find their way into the sea. - GlowWorm. —Preceding unsigned comment added by 98.21.111.233 (talk) 01:33, 9 July 2009 (UTC)[reply]
Relatedness of species / Last common ancestor
Hi all,
I have a bit of confusion about species. I recently learned that if two species had a more recent common ancestor than either of them to a third species, then those two species are considered more closely related to each other than either is to the third species.
A B C
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So B and C are "more closely related" than either is to A.
But what if A and B have barely evolved at all since their respective splits? Say the common ancestor at the bottom splits 100 million years ago and the resulting "A" branch doesn't change ever after (kind of like a crocodile). Soon after (95 m.y.a), the right lineage splits, and the resulting "B" branch doesn't change ever there after. The "C" branch, however, changes tons and tons, and all sorts of other species branch off of that last branch, and C is very, very different from its last common ancestor with B.
In this case, A and B are virtually identical -- they evolved from a LCA in just 5 million years apart and never changed. C is really, really different, though, and has millions of new genes. In this case, wouldn't A and B really be more closely related, even though B and C had the more recent common ancestor? —Preceding unsigned comment added by 76.118.181.97 (talk) 23:27, 8 July 2009 (UTC)[reply]
I believe you will find the answer in the definition of "more closely related". The assertion is correct if you mean more closely in time, and incorrect if you mean more closely in common genes. Avoiding this kind of discrepancy is why scientists talk like a bunch of nerds. --Sean23:35, 8 July 2009 (UTC)[reply]
Both ways of describing how closely related species are are useful and so both are used. It's very common so see statements about what percentage of genes two species share (even that varies depending on your exact definitions). --Tango (talk) 00:53, 9 July 2009 (UTC)[reply]
The use of the term "closely related" is used pretty much exactly like it is in your family tree; just because your second cousin look a lot like you doesn't make him more closely related to you than your sister. You may also find the article on convergent evolution to be germane; it is often the case that even totally unrelated organisms can look similar due to being exposed to similar environmental pressures. Matt Deres (talk) 01:42, 9 July 2009 (UTC)[reply]
There are almost certainly genes that B and C share that A doesn't have...that makes them (genetically) more closely related than A and B. SteveBaker (talk) 02:38, 9 July 2009 (UTC)[reply]
The diagram you gave (as described) was only the qualitative branching. You can make it more quantitative to illustrate the amount of evolutionary change ("...and then C evolves much further while A and B did not change much or diverge very far"):
C
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B |
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and now it's more clear that while B and A are more diverged from each other than B and C are, C has evolved further from A than B has. See our Phylogenetic tree article for several different types of representations (with actual diagrams vs our quick'n'dirty ASCII art:) DMacks (talk) 07:35, 9 July 2009 (UTC)[reply]
July 9
Rubbish/Garbage Island
Would it be feasible to create a new island at somewhere like the Dogger bank (which I understand is a large sand bank off the coast of Britain that you can walk on at low tide) merely by dumping the nation's garbage/rubbish there for a few years? If needed, the rubbish could be contained by an earth or sand wall around it. Such an island would be usefull to put things on like wind farms, nuclear power stations, oil refineries, chemical plants, and prisons. I expect it could take a decade or two for the rubbish to stabilise enough to build on, unless you used deep-pile foundations. 78.147.135.194 (talk) 00:09, 9 July 2009 (UTC)[reply]
The major problem is erosion which could compromise the integrity of the artificial island so maintenance would be expensive since garbage is not exactly as tough as granite. There's also the problem of the garbage contaminating the sea.--Lenticel(talk)00:55, 9 July 2009 (UTC)[reply]
It would be feasible to create an island that way but it probably wouldn't be permitted. Garbage in water tends to, um, exude aspects of its essence, so to speak. Looie496 (talk) 00:56, 9 July 2009 (UTC)[reply]
Landfill is a major method of constructing new land over former waterways. However, garbage (rather, post-consumer waste) has many properties that make it unsuitable for construction of buildings - most notably, it is too squishy for safe construction of building foundations. A lot of engineering has to go into the landfill design to make sure that the ground is solid enough to use. Also, there are potential aesthetic (smell) and health issues, depending on the type of garbage used to build it. However, in some cases, garbage has been used as a fill constituent, properly mixed with other construction materials. Boston and some parts of the United Arab Emirates are notable examples of this. In fact, most of the Back Bay is artificial land; the fill is largely imported from elsewhere in the state, but was mostly dry ground (not garbage). Here is a thorough history from Boston College. Nimur (talk) 01:32, 9 July 2009 (UTC)[reply]
Here's our article on the Palm Islands, in Dubai. The fill material is mostly quarried rock and sand; I can not find any indication that post-consumer waste was used anywhere.
"Would it be feasible to create a new island... merely by dumping the nation's garbage/rubbish there for a few years?" -- Now why in the world would anyone want to do that? There are other much better options for garbage disposal (reclamation, trash-to-steam incineration, etc., etc.), and if you want to build an artificial island, then gravel would work one hell of a lot better.
76.21.37.87 (talk) 06:28, 9 July 2009 (UTC)[reply]
A good example of what you'r looking for is Pulau Semakau, the scenic landfill of Singapore. Even referred to as The island paradise built on a garbage dump[36]. The trick appears to be using incinerated trash. EverGreg (talk) 08:54, 9 July 2009 (UTC)[reply]
A friend and I walked through some brush in Nova Scotia yesterday and emerged with many of these on our pants and shoes. We got them off quickly and didn't appear to have been bitten or anything. What is it? Thanks, Kinou (talk) 00:15, 9 July 2009 (UTC)[reply]
Sure looks like a tick (see pics in tick article). Don't know what kind. But get in the shower as soon as you can, and check yourself very carefully ALL OVER (scalp, nether regions etc.) for any ticks that may have stuck to you, or any bite marks. Ticks can spread some pretty nasty diseases. 208.70.31.206 (talk) 00:40, 9 July 2009 (UTC)[reply]
If you search for images of a wood tick, you'll find a bunch that look just like that. Brown dog tick also looks similar—but I can't decide, and I'm not an expert. Alfonse Stompanato (talk) 00:44, 9 July 2009 (UTC)[reply]
Railroad train wheels
After reading most of the references on trains I have nor found the answer to this question. "What keeps a train on the track around curves"?. Cars do it by virtue of a differential, but train axels are solid so both wheels travel at the same speed. I know the answer but I wonder who invented the cone shaped wheel? What are the limitation of speed around curves? I would appreciate all serious answers. Thanks, wsc. —Preceding unsigned comment added by 98.149.228.69 (talk) 00:33, 9 July 2009 (UTC)[reply]
I see some detailed math related to conical wheels way back in Byrne, Oliver (1862). "The elevation of the exterior rail on railroad curves"(PDF). The Civil engineer and architect's journal. 25: 71–72. {{cite journal}}: Unknown parameter |day= ignored (help); Unknown parameter |month= ignored (help) There actually are differentials for railroad wheels available now, for example see US patent 7316436, Kummings, John, "Differential wheel mounting for railroad car", issued 2008-01-08 and its cited precedents. DMacks (talk) 01:29, 9 July 2009 (UTC)[reply]
If I can digress a bit, the top of the rail is somewhat rounded, even on straight runs. Together with the cone shaped wheels, does that help overcome lurching of the carriage? - GlowWorm.
The reason I think that will help overcome lurching is that the side of the carriage in the direction of lurch will rise slightly, opposing the lurch. The cone shaped wheel will then ride on a slightly different track on the rail top, hence the rounding. This effect would also help oppose the centrifugal "force" on a curve, like a banked auto race-track. These effects may seem slight, but the wheel rim is actually tapered quiite a bit. - GlowWorm. —Preceding unsigned comment added by 98.21.111.233 (talk) 02:56, 9 July 2009 (UTC)[reply]
P.P.S. The train wheels slide sideways on the rails to bring these effects about. That's no problem. We've all heard a locomotive spinning its wheels when starting to move.- GlowWorm. —Preceding unsigned comment added by 98.21.111.233 (talk) 03:41, 9 July 2009 (UTC)[reply]
The Wikipedia article Wheelset says a bit about conical wheels. But I think it is incomplete and poorly written.. Also, it says "Most wheels have a conical shape of about 1 in 20.", which is unclear. - GlowWorm. —Preceding unsigned comment added by 98.17.35.216 (talk) 04:47, 10 July 2009 (UTC)[reply]
It means that the conical surface deviates from the angle it would have if it was cylindrical by about 2.86° (I'm sure that's excessive precision) -- because the tangent of that angle is 1/20. In Britain the style "1 in n" is very commonly used to express the inclination of a gradient on a road or railway, so if one of those is rising at 2.86° above the horizontal, that's a "1 in 20 grade". (In North America we would instead convert the tangent to a percentage and call it a 5% grade.) --Anonymous, 05:13 UTC, July 10, 2009.
The problem I have with a cone angle of "1 in 20" is whether it applies to the angle between the two sides of the cone, or whether it applies to the angle between one side and the axis of the cone. - GlowWorm. —Preceding unsigned comment added by 98.17.35.216 (talk) 05:38, 10 July 2009 (UTC)[reply]
There's a reasonable discussion in an Institute of Civil Engineers publication on google, Cost-effective maintenance of railway track which tends to corroborate much of this discussion. As to cone angle, if this definition is correct then 98.17's objection does not apply. I should like to know the maths by which 1 in 20 comes to be 2.86°, GlowWorm, if you'd be so kind. --Tagishsimon(talk)10:43, 10 July 2009 (UTC)[reply]
I said above: the tangent of 2.86° is 1/20. --Anon, 05:43 UTC, July 11, 2009.
Tagishsimon's reference shows another useful function of conical wheels. It is the reduction of "hunting". Figure 3 shows it clearly and simply. - GlowWorm. —Preceding unsigned comment added by 98.17.47.39 (talk) 22:22, 10 July 2009 (UTC)[reply]
Our article presents several examples of hypodermic uses that are intended for "non-specialists", which suggests that they are commonly used without a medical prescription. Nimur (talk) 01:38, 9 July 2009 (UTC)[reply]
No it doesn't!! It says nothing of the sort! It lists a bunch of medical conditions that would require people to inject themselves...but with a prescription syringe - then it says that recreational drug users use them (illegally) - and only in the next section does it point out that the syringe MINUS THE NEEDLE is used in various industrial applications. Certainly the syringe part is useful without the hypodermic part - and the odds are good that those are perfectly legal. But the article doesn't give a single legal, non-prescription use for hypodermic needles - which is what our OP actually cares about. SteveBaker (talk) 02:14, 9 July 2009 (UTC)[reply]
Needles, like hypodermic needles? Those may be regulated, but they are not what is necessary for ear pearcing. Why not just head to the piercing kiosk at your local mall. For the cost of a $10.00 set of cheap starter studs, they'll pierce your ears for free! --Jayron32.talk.contribs02:33, 9 July 2009 (UTC)[reply]
You can buy a complete ear piercing kit (no illegal hypodermics involved) here for $70. You can buy proper (sterile) ear piercing needles here for about $1.50...they seem very similar to hypodermic needles - but they don't have the fitting to attach to a syringe. I suppose that's what makes them legal...but who knows? SteveBaker (talk) 03:13, 9 July 2009 (UTC)[reply]
I’m not an expert on piercing, and it’s hard to tell for sure from the picture, but my guess is that piercing needles aren’t hollow. There’d be no need for them to be hollow, since no fluid needs to go through them. So piercing needles would be useless to a drug addict, and there’d be no need to make them a legally controlled device. Red Act (talk) 03:24, 9 July 2009 (UTC)[reply]
Years ago someone stole a bunch of analytical-HPLC syringes from a lab where I worked. For those playing along at home, that means the syringes hold a few tens of microliters and the needles are blunt. We figured it'd be easy for the cops to find the druggie who was not high and had a line of bruises instead of needle-tracks up his arm. DMacks (talk) 03:35, 9 July 2009 (UTC)[reply]
I don't know what's in kits sold to the general public, but Body piercing#Contemporary piercing procedures says hollow needles are used. My WP:OR is "may as well go with a cheap, widely available, sterile existing item" rather than something less common or more special-purpose (i.e., more expensive). DMacks (talk) 03:32, 9 July 2009 (UTC)[reply]
If they actually are illegal then what do they pack into ink jet cartridge refill kits sold in that state? The one's I've bought so far all contained a hypodermic needle. I doubt they are sterile, though. (Not a known transmission path for computer viruses :-) 71.236.26.74 (talk) 04:28, 9 July 2009 (UTC)[reply]
A company recently released polyisoprene condoms to the market. Reading that entry says it's natural rubber. How does it compare with latex condoms as far as allergies, strength, and protection? --70.167.58.6 (talk) 01:41, 9 July 2009 (UTC)[reply]
Yeah, they just try to come up with all kinds of fancy words for everyday materials to trick customers into thinking that it's something really high-tech (e.g. "anionic detergents" or "alkali-metal salts of trans-fatty-acids" -- any guesses as to what this stuff could be? (Hint: both of these terms describe pretty much the same material.))
76.21.37.87 (talk) 05:10, 11 July 2009 (UTC)[reply]
Purification of fish oil
Does anyone know how fish oil is purified? I've seen a fish oil product which says on its bottle that it is purified by molecular distillation. Is the distillate purified fish oil or is it volatile impurities? What is the effectiveness of the process? Is it able to remove many broad classes of impurities/contaminants, or is it only effective against very specific ones? What level of purity can be expected from fish oil purified by that process? —Preceding unsigned comment added by 98.114.146.41 (talk) 03:01, 9 July 2009 (UTC)[reply]
Distillation separates the components out by boiling point - therefor it is up to the maufacturer as to which Fraction (chemistry) (s) they put into the final product. In general you should read about distillation to find out about potential limitations of this method.83.100.250.79 (talk) 15:36, 12 July 2009 (UTC)[reply]
In general distillation can remove many impurities - but if there are impurities with similar boiling point to the product it will be less effective.83.100.250.79 (talk) 15:37, 12 July 2009 (UTC)[reply]
oscillators and frequency.
How are oscillators and frequency related to each other?Is constant frequency a compulsion for generating oscillations?please help!! —Preceding unsigned comment added by 210.212.103.10 (talk) 07:20, 9 July 2009 (UTC)[reply]
An Oscillator is something which oscillates, that is, goes back and forth. So when something goes back and forth, each round is called an Oscillation. Now it takes some time to complete each oscillation. This is called Time Period of the oscillation. Now, the inverse of this, that is, 1/t, is called the frequency of oscillation. This need or need not remain constant with time; it is an inherent characteristic of something which oscillates. For more information, please read the relevant articles. Rkr1991 (talk) 08:27, 9 July 2009 (UTC)[reply]
Calculating time to full battery recharge
I need a little help calculating how long it would take to charge the battery pack of an electric vehicle with the following parameters:
The vehicle has six 12-volt flooded electrolyte batteries, and an on-board 72-volt DC charger that plugs into a standard 110-volt AC 15-amp outlet.
The manufacturer of this particularly odious Neighborhood electric vehicle (they're all a little odious) doesn't mention the time to full charge in its published specs- a rather telling omission, I think.
Do you know what is the batteries' storage capacity in amp-hours? If you do, then it's a rather easy calculation (for me, at least), but if not, then the calculation becomes absolutely impossible.
76.21.37.87 (talk) 09:06, 9 July 2009 (UTC)[reply]
I noticed that the on-line calculators I found (before posting this here) were asking for that information, and since I didn't have it, I couldn't use those calculators. But above, I provide all the information that's offered at the company's website. So you're saying that it's impossible to know without the storage capacity in amp-hours. OK, got it. Thanks for the info. Wolfgangus (talk) 09:15, 9 July 2009 (UTC)[reply]
Another consideration is that while the charger uses a 15A 110V hookup, that will not likely lead you to the actual charge current of the device (22A if the device is almost 100% efficient, which it likely isn't even close). Knowing the sustained charging current is critical to know how fast those amp-hours will be replenished.--Jmeden2000 (talk) 19:58, 9 July 2009 (UTC)[reply]
And the other problem (with at least some sorts of battery) is that they can overheat if you charge them at full speed - so you may have to charge them in briefer pulses to keep them from self-destructing. SteveBaker (talk) 04:37, 11 July 2009 (UTC)[reply]
Of course it's possible, and had actually happened numerous times (surprisingly, the planes involved usually sustain little if any damage from the lightning strike).
76.21.37.87 (talk) 09:29, 9 July 2009 (UTC)[reply]
A simple Google will find a lot of reliable sources discussion this [37]. A frequently made claim is that statistically aeroplanes will be hit by lightning an average of twice a year. You can probably also find a lot of discussion when looking in to the recent Air France crash. Nil Einne (talk) 10:22, 9 July 2009 (UTC)[reply]
That, as the man said in Men in Black (film), was on Jeopardy! last night"! The current champion, Alyssa McRae, was once in a plane that was hit by lightning, and she talked about it on the show... which, conveniently, I taped. She said: "You look out the window and see a bright flash, and it feels like the plane has hit something, and you just prepare to meet your maker. And it keeps going, apparently. I don't know if that's what always happens, but for me that's how it happened." --Anonymous, 20:08 UTC, July 9, 2009.
My knowledge of the issue is that most aircraft are protected/relatively good at withstanding a cloud-to-ground lightning strike. Issues come from different types of lightning such as ground-to-cloud which strike the underside of the plane, and sheet lightning. Some planes aren't quite as well adapted to these types, and it can cause issues. Regards, --—Cyclonenim | Chat 16:17, 9 July 2009 (UTC)[reply]
I've actually been in an aircraft that was struck by lightning. It's a lot less dramatic than you might think. My father used to fly for the flying doctor service in Kenya - which is based in Nairobi (hmm - we don't seem to have an article on the East-African flying doctors) - and on one occasion I went out with him (I was just a kid at the time - maybe 12 years old) and we got caught in a nasty storm. The meteorology services in Kenya left something to be desired in the mid 1960's - so we didn't know it was in our way until it was too late. We couldn't get above it because Nairobi is already something like 7,000 feet above sea level and the poor little Cessna doesn't have enough altitude ceiling to get much higher than that - and the plane was somewhat overloaded with land-rover parts that were going out to some back-of-beyond medical center. My recollection was of an extremely bright flash - followed by some complete confusion as the cockpit instruments went nuts and our eyes gradually adapted to normal light levels - but after not very long, everything settled down and enough of the old mechanical instruments worked to get us back to Nairobi without problems. The plane was a high-wing nose-wheel Cessna...a Cessna 172 probably. There was a scorch mark on top and bottom of the wing - maybe an inch or so across and the bulk of the energy seemed to have flowed through a 'stringer' in the wing - melting one of the rivets that held it in place. The damage was fixed in a matter of hours and the plane was back in service on the following day. (The way that outfit worked - it would probably have been flying again the next day WITHOUT the damage being fixed!) SteveBaker (talk) 15:34, 10 July 2009 (UTC)[reply]
Preparing for war
How well prepared are modern Western democracies? Do governments care about provisions of food, energy, and medicines?
It varies, country to country, but I expect most are prepared for reasonable wars or warlike scenarios. Independent of warlike scenarios, governments are always concerned with the supply of food, energy, and medicine. After all, the disruption of such supplies has been a casus belli in the past. The US' 1940 oil embargo on Japan springs to mind as one such. — Lomn12:35, 9 July 2009 (UTC)[reply]
Several western democracies are involved in wars at the moment (eg. Iraq, Afganistan, although they are often euphemistically called "conflicts"), but I assume you mean wars where fighting takes place nearer to home. Most countries have some kind of contingency plans, but I don't know if there would be anything particularly specific. You generally get some warning of wars. Prior to World War II and during the Cold War there were all kind of preparations going on. At the moment there is no reason to expect any major wars, so there is no need for much preparation. There are all kinds of preparations for major terrorist attacks, though, since those are far more likely. --Tango (talk) 16:39, 9 July 2009 (UTC)[reply]
Few countries have military-quality petroleum reserves. The United States has one of the largest, but it is for mostly economic reasons. No country has more than, IFRC, 60 days' worth of petroleum. Even if regular citizens were cut off, that is simply not enough to sustain modern military operations. See the IEA for more on that point.
If every country went to war with every other, only the oil-producing nations would still have airplanes flying and tanks rolling and ships sailing after about a year. Andyo2000 (talk) 19:07, 9 July 2009 (UTC)[reply]
Assuming they retained the infrastructure to continue to produce their oil perhaps, but such infrastructure is a high priority target, and it would not be likely to escape unscathed. Googlemeister (talk) 19:10, 9 July 2009 (UTC)[reply]
...as has twice been demonstrated in recent history. With modern aerial warfare, these longer term considerations of running out of 'stuff' don't apply when a powerful nation attacks a weaker one. It's usually all over in a matter of days to weeks. SteveBaker (talk) 14:58, 10 July 2009 (UTC)[reply]
Well, the large-scale fighting is over within days or weeks, getting full control of the newly occupied territory can take far longer. The initial invasion of Iraq, for example, took about 20 days, but the conflict still isn't over. --Tango (talk) 16:46, 10 July 2009 (UTC)[reply]
In any case, as far as petroleum supplies are concerned, it is the initial large-scale fighting that depends critically upon those; the guerilla warfare that (often) follows afterward is mostly infantry warfare that uses lots of ammunition and food supplies but relatively little fuel. FWiW
I believe the question is asking which is the original color and which is an adaptation. It depends entirely on who you want to listen to. Nobody was around when the first humans were walking around so nobody knows for sure. Of course, that assumes there was a single group known as the first humans. There may have been been many groups of so-called humans that, over time, intermixed. -- kainaw™21:56, 9 July 2009 (UTC)[reply]
Oh. I never thought of that. I thought he was asking what evolutionary advantage each colour inferred, and what pressure there was on it to change. Vimescarrot (talk) 22:04, 9 July 2009 (UTC)[reply]
The mainstream model of human origins is the Out-of-Africa model. And mean skin color within a population adapts to UV radiation levels from the sun quite rapidly (500-1000 years) on human evolutionary time scales. So if the mainstream model of human origins is correct, homo sapiens presumably originally had dark skin, due to the advantage of dark skin in Africa, where there is a lot of UV radiation, and light skin arose fairly rapidly among those populations that migrated to parts of the world further from the equator, where lighter skin is an advantage. Red Act (talk) 00:47, 10 July 2009 (UTC)[reply]
That is not quite as much a given as it may seem. If the humans that made it out of Africa were still very hairy, their skin underneath might well have been light (like e.g. Chimpanzee) The dark skin might then have developed in Africa as an adaptation later. Not saying that is what happened, just saying it's just as likely. (BTW Polar bears have dark skin.)71.236.26.74 (talk) 10:14, 10 July 2009 (UTC)[reply]
If the humans that left Africa remained very hairy, that hypothesis would involve widely dispersed populations all evolving from being very hairy to having little hair. It makes more sense to assume that the evolutionary loss of hair occurred while all or at least most humans were in reasonably close genetic contact. Otherwise, it seems likely that there would be some humans in some isolated parts of the world that retained the thick, chimp-like hair. Red Act (talk) 11:05, 10 July 2009 (UTC)[reply]
Then, we have to make assumptions about how the non-hairy humans got to Africa to start the "out-of-Africa" process. What if they were originally from South America, became ocean creatures, lost much of their hair (as the ocean mammals tend to do), and popped out of the Ocean in Africa? Then, they could have been rather gray at first and turned black. The problem is identifying the first "human". -- kainaw™11:11, 10 July 2009 (UTC)[reply]
According to the Recent African origin of modern humans article, “According to both genetic and fossil evidence, archaic Homo sapiens evolved to anatomically modern humans solely in Africa, between 200,000 and 100,000 years ago ... The recent single origin of modern humans in East Africa is currently the near consensus position held within the scientific community.” I’m just going with the scientific consensus about human origins. Red Act (talk) 11:25, 10 July 2009 (UTC)[reply]
I'm not challenging that, however your comment above would rule out any further development of "anatomically modern humans" after the out of Africa movement. The fact there are no pockets of all hairy populations is not conclusive proof. Parallel development is not unheard of in humans [38]. There are people with Hypertrichosis, but that condition is poorly understood. I don't think the exact conditions for humans to have less hair is not yet conclusively known. (There are indications for genetic causes, but environmental factors are also being considered [39].) If the genetic or environmental condition that caused less hairiness were encountered equally by all human populations in their development, there is no need for it to have occurred before the split. "May have happened" is not equal to "must have happened" even if the latter fits nicely with one's assumptions. 71.236.26.74 (talk) 12:26, 10 July 2009 (UTC)[reply]
Dude, did you even glance at the second reference in your post ([40])? It’s about root hair, a feature of a plant’s roots, and has nothing whatsoever to do with when, where or why our ancient ancestors lost most of their body hair. Red Act (talk) 14:01, 10 July 2009 (UTC)[reply]
Homo sapiens has nothing to do with it. Homo lost its body hair long before that, before 1 million years ago. The "ocean creature" scenario is in fact a respectable theory, known as the aquatic ape hypothesis --dab(𒁳)13:39, 10 July 2009 (UTC)[reply]
That is a point I was intending to make... If you say "homo sapien", you have a rather precise point of evolutionary development. If you say "human", it is very fuzzy. At what point along evolution do you consider the animal to be a "human"? Then, there is the issue that none of the skin of those pre-homo-sapien creatures is around to take a gander at. So, we can only consider other mammals that have had almost no adaptation since pre-human times, such as the hedgehog. A common hedgehog's skin is greyish-pink, but the Algerian hedgehog is almost black. Again, we have to work out which came first, the pink hedgehog or the black hedgehog. So, I don't see any means of answering this question with the knowledge available today. -- kainaw™14:09, 10 July 2009 (UTC)[reply]
Note that my exact original statement above was “…homo sapiens presumably originally had dark skin…”. “Homo sapiens” and “originally” pins the time I was talking about down to about 200,000 years ago, at which point, according to the most widely accepted theory, all our ancestors had little hair, and were living in Africa. However, the original question is completely vague about what evolutionary time scale is to be considered.
The questioner did not ask about "homo sapiens". The questioner asked about "skin color". An answer limited only to homo sapiens is barely a partial answer. Which came first, light skin or dark skin? -- kainaw™20:49, 10 July 2009 (UTC)[reply]
In most animals, dark skin is a result of chromatophores; usually neural crest derived melanophores or melanocytes invading the epidermal or dermal layers after they have already formed. Without this process the skin is functional, but light (consider, for example, albinos). Light skin therefore precedes dark skin in ontogeny; if one considers the most parsimonious method of how skin tone evolved, it is most likely that light skin will have preceded dark skin evolutionarily too. Of course, this will all have happened long before humans arrived on the scene. Rockpocket00:17, 11 July 2009 (UTC)[reply]
NH4CL
when ammonium chloride sublimes, it forms nitric acid and hydroclhoric acid. i wanted to ask if this reaction is physical or chemical. cos, this reaction is reversible (in wiki, it's written - "Ammonium chloride sublimes readily but this process involves dissociation into ammonia and hydrochloric acid followed by reforming of the compound." but i know perfectly well that this reaction is also chemical, as it involves chemical changes, and not simple physical changes.
please help me! (PHYSICAL OR CHEMICAL?????)
thanx!!!!!!! —Preceding unsigned comment added by 122.50.134.64 (talk) 13:10, 9 July 2009 (UTC)[reply]
When ammonium chloride sublimes, it does NOT form nitric acid and hydrochloric acid. It forms ammonia and hydrochloric acid. Also, it should be noted that all chemical changes are also physical changes; it is impossible for a chemcial reaction to happen which does also not change some physical property of the materials. When one says "physical change" they are implying only a physical change; that is one in which the shape, size, or state of matter of a substance is changed without making a change to the composition of the substance. So the answer here is that this is clearly a chemical change, since the change results in different chemicals being formed after the change than before. Physical changes would involve such simple things as smashing the ammonium chloride into little bits or dissolving it in water. --Jayron32.talk.contribs13:15, 9 July 2009 (UTC)[reply]
Isn't the whole division of changes into physical and chemical somewhat artificial?
We say melting is a physical, not chemical, change, but you are changing the bonding situation going from solid to liquid.
It is artificial, but it is something that is common in beginner-level chemistry textbooks. I honestly can't remember the definitions now, but it was simplified to three or four points. —Akrabbimtalk20:01, 9 July 2009 (UTC)[reply]
Like many parts of introductory high-school level classes, a big part of the curriculum is about organizing your thinking rather than just presenting actual facts. The idea behind recognizing "chemical" processes vs. "physical" processes is in the first about learning to categorize things. Secondarily, it is about recognizing what a "chemical" is, and what it means for a chemical reaction to occur. It is not readily apparent to most people that a process like melting is not a chemical process (but it was "ice" before and "water" after? Isn't that two different things??? (Ans: no...) ) or that dissolving salt in water is not a chemical process (but, like, the salt dissappears!) Recognizing what sorts of things can be counted as chemical reactions and which are not requires some training... Which is what this activity is also about. Usually in the first week of high school chemistry, besides learning this, one also learns basic classification schemes of matter, so that one can recognize the difference between, say, a pure substance and a mixture of substances, or between a heterogeneous mixture and a solution. --Jayron32.talk.contribs20:21, 9 July 2009 (UTC)[reply]
Indeed. But you can learn how to categorise things without resorting to concepts that are not really important to real scientists.
I guess you could say chemical changes involve breaking and forming chemical bonds. But there are many processes that are traditionally considered physical which do in fact involve bond fission and formation. For example, water boiling. Intermolecularhydrogen bonds are broken as the liquid turns into gas. It all seems a bit pointless to me.
I imagine it would be perfectly possible to avoid classifying things as physical or chemical changes and just talk about what's actually going on at the molecular scale. Dissolving is one of those processes that falls on the border between chemical and physical: Na+···Cl− ionic bonds are broken and ion-water interactions form, energy changes hands (enthalpy change of solution is +3.9 kJ/mol), you can write a chemical equation for the process {NaCl(s) + aq → Na+(aq) + Cl−(aq)}, and the product (NaCl solution) has very different properties from the starting materials (NaCl(s) and water).
It's a bit late at night, so my interpretation is a bit fuzzy, but from what the last two posts above me have said, it seems they're discussing lies to children - which is a good and necessary thing. The link might be useful to either of them, or to anyone interested in what they were saying. Vimescarrot (talk) 22:02, 9 July 2009 (UTC)[reply]
Its not really lies; its more of a bridging heuristic. Its not that, several weeks later, we don't teach more details about these things. Its more of a learning to crawl before you walk thing. Yes, some kids can walk right away, but many need the extra help crawling first. They can all get there, but just as you wouldn't teach someone to read Shakespeare before you read Dr. Seuss, generally we teach the simplified stuff first. --Jayron32.talk.contribs01:25, 10 July 2009 (UTC)[reply]
Plasma weapons
We see plasma weapons in movies and games all the time. I didnt understand what plasma was until I played Halo. The plasma pistol and rifle in the game are powered by batteries and when I fired it on a wall it would show a sort of melting of the wall. I suppose the batteries heat up the plasma. What really is plasma and can such weapons be really made? —Preceding unsigned comment added by 116.71.49.65 (talk) 16:17, 9 July 2009 (UTC)[reply]
Welcome to Wikipedia. You can easily look up this topic yourself. Please see plasma weapon. For future questions, try using the search box at the top left of the screen. It's much quicker, and you will probably find a clearer answer. If you still don't understand, add a further question below by clicking the "edit" button to the right of your question title. --Shantavira|feed me16:28, 9 July 2009 (UTC)[reply]
Weapons in science fiction stories (including games) tend to be based more about looking and sounding good, than any sound scientific principles, so don't expect to see a Type-25 Directed Energy Rifle to look anything like it does in the game, if it's remotely possible to make a weapon on the same principles. Vimescarrot (talk) 18:55, 9 July 2009 (UTC)[reply]
In almost every case they grossly underestimate the amount of power needed to make such things do what they do in the game. Sure, you could probably make something that sat on the back of a large truck...with another two large trucks full of batteries to power it...but something you could lug around like a machinegun is really not reasonable. The stored energy for any weapon has to come from somewhere - and there are few sources of energy more 'dense' (in terms of power-to-weight ratio) than explosives. This is the main reason why we don't see people using laser pistols and rail guns out on real battlefields. Game designers (and I'm a games programmer - not a designer) don't care to be limited by the bounds of what is realistic - and that's a good thing in many ways because breaking the shackles of reality is what makes most games fun. SteveBaker (talk) 04:34, 11 July 2009 (UTC)[reply]
"Sure, you could probably make something that sat on the back of a large truck...with another two large trucks full of batteries to power it..." -- I think they actually made a plasma cannon that would just barely fit inside a jumbo jet (the plasma generating equipment and the batteries, plus all the fire-control computers and whatnot, took up most of the fuselage). So that would give you some idea of how big a plasma cannon would be in real life.76.21.37.87 (talk) 05:32, 11 July 2009 (UTC)[reply]
Does Freeview transmit software updates for TVs? I know it sounds unlikely, but I swear my TV (which has an integrated freeview receiver) announced a couple of days ago that a software update was available & did I want to install it. So. Unlikely as it sounds, does Freeview transmit software updates for TVs? --Tagishsimon(talk)22:06, 9 July 2009 (UTC)[reply]
Well, for one thing, on human time scales, the collision of the galaxies wouldn’t be an event to observe, so much as a very long process, of which only a small portion would be visible within one lifetime. The milky way galaxy has a diameter of 100,000 light-years, and the colliding galaxy would be approaching at sub-light speeds, so the collision process would take perhaps a million years. Red Act (talk) 23:19, 9 July 2009 (UTC)[reply]
For one thing, the band of light which is the Milky Way would appear much different, depending on the other galaxy's angle of approach. Red Act is right, though, in saying that we probably wouldn't see much of anything in terms of dynamic movement or astronomical events; the likelihood of even one star colliding with another during this process is minimal. Perhaps the supermassive black hole at the galaxy's center would be a bit more active due to an increase in infalling matter, but that would only be of interest to astronomers. -RunningOnBrains(talk page)23:27, 9 July 2009 (UTC)[reply]
I remember reading somewhere that when M31 and the Milky Way collide, out of the ~250 billion stars in both galaxies combined, no more than five actual stellar collisions are expected to occur. That's like 2 * 10-9 percent of the stars. J.delanoygabsadds23:51, 9 July 2009 (UTC)[reply]
This is correct. When galaxies collide, essentially none of the stars actually run into each other. But the gas does, causing a massive starburst, which means lots of bright blue stars and spectacular emission nebulae. Plus a whole load of supernovae going off. Of course, the time scale for this sort of thing is on the tens of millions of years. On a rather smaller scale, the Large Magellanic Cloud is currently running into the Milky Way, only one galaxy (the MW) is much more massive than the other (the LMC). If you go to the southern hemisphere, you can easily see the LMC with the naked eye from a dark site - it's much bigger than the full moon and looks like a detached bit of the Milky Way. And you can see the SMC too. Modest Geniustalk03:06, 10 July 2009 (UTC)[reply]
They look dense because the instrument taking the photo doesn't have the resolving power to show just how small stars are compared to galaxies. For that matter, your screen doesn't have pixels small enough for that either. Algebraist16:21, 10 July 2009 (UTC)[reply]
Bear in mind that the ratio between the distance to the nearest star to the diameter of the sun is about 30 million to one. there's a lot of empty space. Modest Geniustalk23:08, 10 July 2009 (UTC)[reply]
July 10
SAT identification
Yesterday (July 8) at around 11:17 local time I saw two satellites, separated by about a degree, pass by Cassiopeia. They were initially both of magnitude 2-3, but dimmed as they climbed higher into the sky. Does anyone know what these satellites are, and why they have nearly the same orbit? I live in Toronto. Before you suggest one of the them was the ISS and the other was a spacecraft trying to dock with it, that can't be it because I saw the ISS pass by several minutes later. Interestingly, a search on Heavens Above turned up nothing. --Bowlhover (talk) 00:11, 10 July 2009 (UTC)[reply]
Is this the kind of drug for which users develop a tolerance, requiring higher doses to achieve the desired effect? If so, does the fatal dose also increase as tolerance goes up?
This is not a request for medical advice, this is part of my research in writing a work of fiction based on the life of Nick Drake, who died from an overdose of this drug. -GTBacchus(talk)01:22, 10 July 2009 (UTC)[reply]
In short, yes. In this study, tolerance to the effects of amitriptyline built up differentially over measures of sedation, psychomotor function and memory. See also [42]. - Nunh-huh02:50, 10 July 2009 (UTC)[reply]
The word "tolerance" may be a bit misleading when it comes to antidepressants. A great deal of research shows that it usually takes a couple of weeks before the mood-altering effect kicks in; however other effects such as sleep alterations kick in immediately. This is often taken to mean that some sort of tolerance-like effect in the brain plays an essential role in the function of the drug. It's generally not the case, as I understand it, that people taking antidepressants need to take steadily increasing doses to get a constant result. Looie496 (talk) 03:16, 10 July 2009 (UTC)[reply]
OR Speaking as a long-term amitriptyline user, it's not the case that I have had to increase the dosage over the years to get the same effect, so no tolerance has been developed. However, I'm now trying to stop taking it and am having to slowly decrease the dose to nothing: so far it's taken 3 months and I'm on course to be off it in another month's time. This is because of the physical side-effects of stopping taking the drug, which include the possibility of heart arrhythmia (or so I understand). You could say I'm addicted to it, under some definitions of addiction. --TammyMoet (talk) 08:51, 10 July 2009 (UTC)(Edit) The only tolerance I had to build up was tolerance of the effects of the drug, in other words, adjusting to the change in sleep patterns the drug brought.--TammyMoet (talk) 08:53, 10 July 2009 (UTC)[reply]
Coriolis force
Suppose a mass m is moving radially from the centre of a moving carousel. There has to be a tangential force in order to keep it moving in a straight line, and my question is what is this force. One way I would do it is to find the angular momentum, differentiate it to find torque, and divide by r to get the force. This gives me 2mw*v_rad. Doing something similar with momentum though, I get half that value (p=mwr, F = dp/dt = mw*v_rad). What did I do wrong? —Preceding unsigned comment added by 70.82.247.24 (talk) 03:23, 10 July 2009 (UTC)[reply]
Momentum and velocity are both vectors. So
where is the particle's radial velocity and is its tangential velocity. So
where I have assumed that vr and ω are constant. Now
It's the same tired arguement that has been going around for years and years. The basic principle is that of "intermediate forms". In order to say that Animal X evolved into Animal Y, there needs to be a "smooth transition" between the two; new structures or forms don't just spring out of no where, the change gradually over time. That's a cornerstone of evolution. So, the creationist side of the debate (which is what creation.com is all about, n'est ce pas?) finds some evolutionary gap in the fossil record, and hammers it home as PROOF that evolution does not happen. First it was the flagellum in single-celled organisms, then it was the eye, now it appears they have latched on to bird lungs. The deal is, finding a SINGLE example which has not yet been adequately explained does not in any way invalidate the entire system.
Look at it this way: Imagine a brick road, with billions of bricks, stretching from Los Angeles to New York. Now, imagine that there are some bricks missing. Like, once every ten or twenty miles, there's a missing brick. Now, imagine saying "I cannot get from LA to New York because there's a brick on this road that is missing. It is impossible to drive that long distance given that the road is not complete." That is exactly what this guy is saying. There are literally millions of pieces of evidence, which DO neatly connect the extinct forms to modern forms via evolution. The deal is, that sometimes there's a bit, like these bird lungs, which has not been discovered yet, or adequately explained yet. Just like the flagellum before it, someone will eventually come along to connect the dots. --Jayron32.talk.contribs04:19, 10 July 2009 (UTC)[reply]
Ignoring the creationist aspect, all reputable paleontologists believe that birds evolved from some type of reptile, but there is a small minority, including the ones interviewed for that program, who think that the reptiles in question were not dinosaurs. Most paleontologists feel that the dinosaur origin is supported beyond reasonable doubt by the existing evidence. Looie496 (talk) 04:43, 10 July 2009 (UTC)[reply]
It you're going to ask a question based on an overtly creationist website report - on a reference desk that's dedicated to giving proper, scientific answers - you cannot reasonably demand that no creationism-versus-evolution discussion will be required. As Jayron32 so eloquently points out - the absence of one tiny step in the path doesn't destroy the argument that birds evolved from dinosaurs. Absences are only to be expected in a science where we mostly rely on chance findings of bazillion year old animals that were frozen in carbonite or something - mostly out in the middle of a few hundred miles of rocky desert in outer mongolia. For there to be a solid consensus that birds did NOT in fact evolve from dinosaurs, there would have to be a piece of contradictory proof that they evolved from something else. Efforts to use these small gaps to somehow "prove" that evolution isn't true are simply not going to convince the vast majority of people in the world. Frankly, the more interesting questions are:
Did birds evolve directly from Dinosaurs? If so, which family?
Did birds and dinosaurs evolve independently from a common ancestor? If so, which ancestor?
Did dinosaurs evolve from birds? (This is a radical viewpoint that is probably pretty much disproved now - but was around when it was first speculated that birds are descended from dinosaurs...the theories were called "Birds are dinosaurs" and "Dinosaurs are birds" - and proponents of the latter liked to use the initial letters to indicate that Birds Are Dinosaurs is a "BAD theory").
"None of the above" does not seem to be a viable theory.
If you're really tough, and I mean Rambo tough, sure you can, but don't take that as medical advice. Just advice from someone who's been places and seen things (or been at home and seen some bad movies). See cauterization. Incidentally, these two consecutive questions, coming from the same poster and taken together, paint a very frightening picture. See a doctor, they won't judge you.--Rallette (talk) 06:56, 10 July 2009 (UTC)[reply]
Since silver nitrate is a cauterizing agent, and was historically used to treat gonorrhea, I’m thinking the connection between the two questions is that the poster’s been doing some reading about silver nitrate, not that the poster is contemplating doing surgery on himself. Red Act (talk) 07:20, 10 July 2009 (UTC)[reply]
It really depends on the context. One of the big differences between cauterization and suturing is what ultimately happens to the patient's SKIN. A cauterized wound will form scar tissue, which shrinks and tightens around the area. If this is a large area, it will likely be extremely uncomfortable and may even require a graft. Cauterization is generally prefered for smaller jobs. Suturing, on the other hand, brings existing regions of skin together, so the resulting scar tissue is much less. Of course, there needs to be skin available for this to even be an option. There are other factors involved, this is just one consideration. It really depends what the injury is you're talking about. --Shaggorama (talk) 14:23, 10 July 2009 (UTC)[reply]
Besides syphilis and gonorrhea, mercury was used to treat ailments as diverse as depression, tuberculosis, toothaches, and constipation.[43] There were essentially no legal restrictions on claims of medical effectiveness back then, so a lot of drugs were touted as curing practically everything. Red Act (talk) 09:37, 10 July 2009 (UTC)[reply]
Are you aware of our "search" function, over on the left there? You could type things like ear infection and click Go, and you'll get a whole article on it. I did so just now, and found that in the page regarding middle ear infections, it sounds like they had to wait until it got severe and then performed a myringotomy. Tempshill (talk) 07:21, 10 July 2009 (UTC)[reply]
There are various folk remedies for earache, one of which involves baking an onion until soft, then removing the core and inserting it into the affected ear. The heat will disperse the gunge, while onions are known to have antiseptic properties. --TammyMoet (talk) 08:46, 10 July 2009 (UTC)[reply]
I've recently read that the outcome for ear infections with or without antibiotics treatment does not differ significantly.[citation needed][dubious – discuss] You can treat them with anti-inflammatory drugs, like Aspirin, and there are any number of folk remedies involving onions and potatoes. --Stephan Schulz (talk) 09:08, 10 July 2009 (UTC)[reply]
In recent years there have been a number of studies showing that "watchful waiting" is a reasonable course of action in uncomplicated acute otitis media in a healthy child. See this [44] for an example. There are many others. Of course, there are rare complications in which the ear infection proceeds to cause mastoiditis or meningitis. So, one needs to weigh the costs and benefits of the treatment. It is argued that since most cases of acute otitis media will resolve on their own (that's what the immune system is for, after all) and since antibiotic therapy is associated with increased antibiotic resistance among the organisms we are trying to treat, we should not immediately give antibiotics every time a child gets an ear infection. Even without immediate antibiotic therapy, the child needs to be re-evaluated within 48 hours or so to make sure that the infection isn't getting worse. Of course, the management decision is a very complicated equation -- how sick is the child? how old is the child? how reliable are the parents? how good will be the follow-up? These are questions the doctor should be asking every time he/she decides whether or not to prescribe antibiotics. And as always, the question continues to be debated. But this is certainly not "dubious". --- Medical geneticist (talk) 11:52, 10 July 2009 (UTC)[reply]
Thanks for the ref. I put in the templates as a mild joke and a reminder that stuff someone recalled from somewhere is not always the best source - even if someone is me ;-) --Stephan Schulz (talk) 12:17, 10 July 2009 (UTC)[reply]
Onion juice dripped into the ear is still used for persistent ear infections. It works as an Anti-inflammatory the compound identified was Quercetin. Onion contains thiosulphinate (no page?!) that works as an antibacterial and antifungal agent [45]. Thyme has Antiseptic properties. So, no they didn't have to wait, some herbal remedies actually are effective without employing products of the pharmaceutical industry (who are quite good at extracting some substances and selling their products at a price several orders of magnitude higher than the origin).71.236.26.74 (talk) 09:57, 10 July 2009 (UTC)[reply]
This page shows the structures for both thiosulfate and thiosulfinate. Note that thiosulfate is a specific compound, and the thiosulfinates are a whole class of compounds. Red Act (talk) 15:33, 10 July 2009 (UTC)[reply]
Hello, my name is corey. I had a question about your definition of a Brain freeze. Now, while i admit your explaination is correct, i also wondered this- would not the "Brain Freeze" in fact be your brain overheating? Because i read an article in a magazine some years back that stated your heart and body forces too much blood to your head which in fact causes it to overheat. The explaination you have refers to the pain suffered from your constricting arteries in the roof of your mouth, but it confuses me. If i wrap something around my arm tightly for ten to twenty seconds, the veins and arteries swell. When i remove it, there is very little pain that comes. If the pain associated with brain freeze comes with shrinking blood vessels why is there no pain when they are swollen? Also, during a brain freeze, one can place theyre hands on the sides of thier neck to relieve the pain- how could this be if the pain is directly stemming from the roof of your mouth?
Sorry, i guess i kinda asked several questions there.
Basically my question i was wondering about is this-
During a brain freeze, does your body push more blood to the area to compensate, thereby causing brain overheating, or is the pain only caused by your blood vessels regrowing to normal size? —Preceding unsigned comment added by 75.164.152.179 (talk) 08:32, 10 July 2009 (UTC)[reply]
In no way am I an expert, but while you wait for a better response, here is my best attempt at answering the question:
There are 2 main theories on the origin of pain, one theory holds that the pain is simply caused by the rapid dilation of the blood vessels of the palate and pain is transferred to the brain via the trigeminal nerve. While the other theory states that the body overreacts to this cold stimulus and pushes more blood to the brain trying to heat it. This alters the follow of the blood in the brain and causes this familiar brief headache. Personally, I am more inclined to believe the latter theory.
I thought blood vessels contracted in the cold, so wouldn't it be rapid contraction, not rapid dilation of blood vessels? Regards, --—Cyclonenim | Chat 18:03, 10 July 2009 (UTC)[reply]
True, but the pain is not usually attributed to vasoconstriction, but to the rapid dilation that follows.
Actually, this question is quite interesting and one which can be to a certain point investigated at home. If the first theory is right, then keeping the cold substance in contact with the roof of the mouth shouldn't cause a brain freeze. On the other hand, if a brain freeze is experienced with the cold substance still in contact, then the second theory is right. In either case, the cold material used should not be allowed to reach body temperature or the results will be invalid.
This is in no way encouraging anyone to try this at home. Don't sue me should permanent damage happen.
You know, im inclined to believe both theories. Ive tested both, and they both seem to have substance. I still don't quite understand it- if both instances are right, do we include both theories in our definition of "Brain Freeze" here on wiki, or do we just shrug off my suggestion that i first posted as merely a possible theory and not a literal possibility? sorry- i'm too inquisitive for my own good :p
Ah, very true. Forgot that little bit there... oh well. I'll keep hunting and researching, see what others have to say about it. If anyone gets more info, please, feel free to place it in here. —Preceding unsigned comment added by Blaze113 (talk • contribs) 09:55, 11 July 2009 (UTC)[reply]
Both mechanisms could be at work, but until someone proves it conclusively, we will never know.
I was in Newcastle railway station this weekend. Sitting waiting for my train to leave, I noticed the tracks on the adjacent line showed an unusual zigzag pattern. I took a photo (it's rather poor mobile-phone quality) which is here. Can anyone explain what these patterns are?
My thoughts are:
it's an artifact of manufacturing, but the tracks really don't look new
it's an artifact of some rail-surface reconditioning machine, but why would it leave this pattern
it's been added to enhance friction (to help trains brake), but why this pattern?
it's caused by the action of train wheels - but it seems much too regular and well defined, and this is a terminal platform where trains are moving slowly and braking very gently
Because I noticed it only once I'd sat in my train, I don't know if other tracks have this pattern, or if this pattern is visible for more than the 20ft or so section I could see. I can't see anything relevant in the rail tracks or the like. 87.113.26.43 (talk) 11:30, 10 July 2009 (UTC)[reply]
I should note, incidentally, that I don't think the pattern is sinusoidal, I really think it is triangle wave with rounded corners. A sinusoidal form might suggest some kind of cleaning or reconditioning machine which moves a helical element down the track, but this doesn't look to be the case for this track. 87.113.26.43 (talk) 11:35, 10 July 2009 (UTC)[reply]
The irregularity of the marking pattern suggests that it has been applied manually. My first guess is that it was drawn by a maintenance worker to identify rail(s) due for replacement or realignment. My second guess is that it marks a stopping point for train drivers to see. Cuddlyable3 (talk) 11:59, 10 July 2009 (UTC)[reply]
I was going to say that I thought it was too regular to be manually applied (at a large scale); at a smaller scale I'd say it had been applied by an angle grinder or some machine with similar function, which makes for a rather rough line. Clever though it is, I don't think your "stopping point" theory is correct - for terminal lines the buffers should be sufficient for that, and for through lines (which this isn't) there are signs which mean "if you're a six car train, stop here". 87.113.26.43 (talk) 12:08, 10 July 2009 (UTC)[reply]
Speaking of stopping, might this be a pattern that facilitates stopping the train if the rails are covered in ice or snow? I seem to recall that last winter British Rail had some stopped services because of ice and snow.71.236.26.74 (talk) 12:35, 10 July 2009 (UTC)[reply]
This section is well inside the canopy of the station, at least 100m from anywhere snow could land. Ice could form, but only from condensation (so not much). It's my understanding that snow-and-ice affects british railways mostly due to points getting frozen. 87.113.26.43 (talk) 12:43, 10 July 2009 (UTC)[reply]
Is that actually etched into the track? In the photo, it looks like chalk markings. They mark tracks to be repaired with chalk here (U.S.). My son loves railroads and we got to walk along the tracks recently when the local railroad was being marked for repairs. -- kainaw™12:49, 10 July 2009 (UTC)[reply]
To me that looks deliberately applied for some reason. I can't think of any reason. Maybe the local kids having input to their surroundings? It also might be a reflection of the overhead structure, having no material presence on the tracks at all. Bus stop (talk) 12:51, 10 July 2009 (UTC)[reply]
It's a rubbish photo: yes, it's definitely etched into the track somehow (I'd say with some kind of grinding tool or wire brush deivce), but only to a very shallow degree (maybe "polished" would be more accurate than "etched"), which is why I don't think it'd be of much help for traction. If it was marking, as you and Cuddlyable3 have suggested, it seems unlikely they'd go to such trouble (surely a chalk mark on the side of the rail would do), and surely track is replaced by removing and replacing a whole length, rather than just a bad section. of a given length. I'm confident it does have some utilitarian purpose, as Network Rail certainly aren't given to fripperies like decorative rail etching. 87.113.26.43 (talk) 12:58, 10 July 2009 (UTC)[reply]
It might be put in at the factory as a wear marker - either to indicate that the rails have worn out or that they've been broken (?) in (more likely, given the shallowness of the markings). --Stephan Schulz (talk) 13:08, 10 July 2009 (UTC)[reply]
My mistake -- it really does exist. (Enlarge photo to see it better.) I also found this picture which might shed some light on it. This could also possibly explain how those marks got there. Bus stop (talk) 13:11, 10 July 2009 (UTC)[reply]
Thanks, I'm very impressed that you found such a clear photo. Note that the track in Bus stop's photo is a through-platform, carrying intercity traffic, rather than a terminal backwater platform. 87.113.26.43 (talk) 13:45, 10 July 2009 (UTC)[reply]
They're rumble strip welds, used improve electrical contact between rail and wheel (for track management, not power). See [47] Paragraph 17. Bazza (talk) 14:34, 10 July 2009 (UTC)[reply]
Fantastic, well done and thanks a lot; the photos in that report look exactly like those in the station. This is just the kind of thing that there should be a wikipedia article about; but I can't seem to find any further information under that name (perhaps they're also called something else). 87.113.26.43 (talk) 15:29, 10 July 2009 (UTC)[reply]
It is done by grinding, it is done intentionally [48] and the book one can not access here [49] says that it's done to avoid exchanging rails which have a rolling contact surface that is still o.k. 71.236.26.74 (talk) 15:06, 10 July 2009 (UTC)[reply]
Wow -- that is it. It is used on stretches of track that do not receive sufficient or fast enough traffic to keep the surfaces clean of oxidation or other detritus. This is to increase electrical conductivity between the wheels and the track, and this in turn is to enable detection of the train in its "berth" in the station. Bus stop (talk) 15:33, 10 July 2009 (UTC)[reply]
From a guide I got that to plant carrots you need a distance between 25 and 30 cm. What would happen if the distance is greater than 30 cm? I suppose that a shorter distance means that the planst will compete with each other, but what speaks against the other case?--Quest09 (talk) 15:47, 10 July 2009 (UTC)[reply]
If you plant your carrots further apart than necessary, than you get less carrots than you could be getting. I expect (but do not know) that that's all there is to it. Algebraist15:50, 10 July 2009 (UTC)[reply]
Plant distances given are a minimum. If you want to plant your carrots 500' apart, it will not bother the carrots, but will make for a lot more time spent walking between your carrot plants then a shorter distance. Googlemeister (talk) 15:56, 10 July 2009 (UTC)[reply]
I assume you are talking about the spacing between rows of carrots. The spacing between plants is only a couple of inches (few centimeters). Rmhermen (talk) 01:57, 11 July 2009 (UTC)[reply]
Why is the temporal bone classified as irregular?
Hi everyone I noticed that most of the bones that encase the human brain such as the parietal, frontal and occiptal bones are all classified as flat bones whereas the temporal bone is not. I've had a look at the article on the temporal bone but it doesn't say why it is classified as an irregular bone whist the other bones that make up the skull are flat bones. Can anyone offer me an explanation or point me in the direction of some info? Cheers RichYPE (talk) 16:26, 10 July 2009 (UTC)[reply]
Would smoking tea or coffee get the caffeine from these products into your bloodstream efficiently enough to be comparable to drinking it? I would think that it would be a quicker way, but I am not sure if the caffeine actually makes it through the burning process or converts into something else. —Preceding unsigned comment added by Frogmaster3950 (talk • contribs) 16:27, 10 July 2009 (UTC)[reply]
Coffee grounds do not burn readily, so you would have to mix them with large quantities of additives. Tobacco is usually soaked in a little butane to help it light; these additives are major contributors to the "unhealthy side effects". The amount of extra additive needed to burn coffee grounds would probably result in an extremely unhealthy concoction. As far as smoking tea, it can be done, but it is generally not regarded as a pleasant aroma (and this is considering that it is compared to smoked tobacco....) Nimur (talk) 16:48, 10 July 2009 (UTC)[reply]
I have actually smoked coffee in a water bong without having any problems with getting it to ignite. My question mainly concerns how readily the caffeine gets from the coffee or tea being burned into your bloodstream.(I have found the smell of both tea and coffee smoke to be no more offensive than tobacco).
I'm not certain of this, but I was under the assumption that if you inefficiently combust organic material (such as by smoking it), it can release carcinogens, producing a cancer risk. For example, burnt toast has some carcinogens. So whether of not it works/is as effective etc, I suspect this danger would mean it would be a less widespread method than simply drinking it. Regards, --—Cyclonenim | Chat 17:12, 10 July 2009 (UTC)[reply]
I am fully aware that inhaling smoke from burning organic material can be carcinogenic. I am not too worried about that because I don't plan on making any kind of habit of smoking either tea or coffee as i enjoy their taste and would just assume to drink them. I am just wondering if anyone knows how readily caffeine is absorbed by inhalation of smoke. —Preceding unsigned comment added by Frogmaster3950 (talk • contribs) 17:30, 10 July 2009 (UTC)[reply]
I once emptied a Lipton's tea bag and rolled the contents into a cigarette. One puff was enough to explain why tea cigarettes aren't being sold. It was nauseating. B00P (talk) 06:03, 11 July 2009 (UTC)[reply]
The only way tea is worth smoking is in a closed pan over just enough heat to keep it smouldering. Slices of salmon or chicken placed over them will cook in the smoke in 15 minutes or so, developing a beautiful golden colour and smokey flavour. The tea leaves should then be discarded. - KoolerStill (talk) 12:05, 12 July 2009 (UTC)[reply]
According to Solzhenitsyn's The Gulag Archipelago, inmates in the Soviet forced-labor camps used to smoke tea, not so much to get high, as to cause self-inflicted heart and lung damage so they wouldn't have to work (the idea behind the labor camps was to literally make the poor devils work till they drop dead). FWiW
76.21.37.87 (talk) 02:27, 13 July 2009 (UTC)[reply]
Evolution of the anus
Serious question, it seems like the human body has changed a lot since our very early (similar to lungfish) ancestors. The human mouth has specialized teeth, limbs have complex hands and fingers, etc. Why does it seem like the human anus has barely changed at all. Are there any major differences between the human anus and other animals? Has the human anus evolved any particular adaptations over evolutionary history? TheFutureAwaits (talk) 18:02, 10 July 2009 (UTC)[reply]
Sure it has, the type of matter that passes through it has changed many times over the eons. Not to mention moving from an aquatic to land based environment. TheFutureAwaits (talk) 18:30, 10 July 2009 (UTC)[reply]
As far as differences go, off the top of my head I can't think of any other animal that has to wipe. Dogs, cats, fish, rabbits, etc, even other primates just pinch it off. No or minimal cleanup is needed after the deed is done. Dismas|(talk)05:28, 11 July 2009 (UTC)[reply]
I imagine that's related to the fact that, whether due to bipedalism or sexual selection or both or something else, human anuses are more 'hidden' between the gluteal muscles (buttocks) than other animals'. Our inconvenient cleanup needs are likely a result of this. Maelin (Talk | Contribs) 05:53, 11 July 2009 (UTC)[reply]
Honestly, I think the anus has been more or less an anus since well before humans were humans. I doubt the human anus is significantly different from that of any other mammal. It's just a sphincter, and its requirements have been more or less constant throughout mammalian development, hence there have been no significant selection pressures to change it. In fact the only thing I can think of is that humans have developed the need to practise hygiene due to the buttocks being in the way, but the anus itself is, I would expect, largely the same as it's been since early mammalian evolution. Maelin (Talk | Contribs) 11:50, 11 July 2009 (UTC)[reply]
The exocarp is the part of the corn that you poop out. Its the same bit that gets stuck in your teeth when you eat popcorn. The stuff inside of the kernel, which contains all of the starches and sugars and protein and fats, is easily digestible. That's what you get nutrition out of. --Jayron32.talk.contribs22:36, 10 July 2009 (UTC)[reply]
In cycling, when one biker uses the draft of another to reduce their energy expenditure, does the biker in front expend more energy "pulling" the biker behind? --71.191.104.213 (talk) 22:43, 10 July 2009 (UTC)[reply]
Almost certainly not significantly, otherwise there would be no net advantage to being in the peloton. What happens is that the group as a whole is more aerodynamic than a single rider. --Stephan Schulz (talk) 23:11, 10 July 2009 (UTC)[reply]
How about just a pair of bikers? Does the one pull the other, or does the one in the rear simply take advantage of an aerodynamic effect that is already occuring behind the first rider? --71.191.104.213 (talk) 23:22, 10 July 2009 (UTC)[reply]
It's certainly the case in car racing that when two cars get up really close, they both benefit. The amount of drag on a car is a function of (amongst other things) it's cross-sectional area. When two cars 'tailgate' each other - it's almost like the two of them are glued together into one car that's twice as long. The total cross-sectional area (and hence the drag) is the same for the two cars as it is for just one of them. When a car experiences drag, it's doing two things - firstly it's pushing the air out of the way at the front - but it's also pulling a drop in pressure at the back - and that takes energy too. In the case of our two car convoy - the one in front is paying the price of pushing the air out of the way - but the one behind is paying to pull the air back in behind it. Which of those is the most costly is hard to guess - it probably depends on all sorts of subtle details of the shape of the cars/bikes/whatever. But certainly it ought to be easier for the guy in front as well as as the guy at the back...it's only a matter of how 'fairly' the overall energy savings are split. SteveBaker (talk) 00:09, 11 July 2009 (UTC)[reply]
Some species of migratory birds fly m a V formation during migration. Does this produce a moving mass of air that assists all of them? (A single bird leaves turbulence behind that simply goes to waste.) Occasionally a straight line of birds is seen, lined in the direction of flight. Is the V formation more aerodynamically efficient than a straight line? A straight line formation is easier to take up than a V formation, so maybe it is an intermediate formation for intermediate-duration flights. I think I remember reading that from time to time the lead bird in a V formation gives its place to another bird. Is that because the lead bird has the most exhausting job, without other birds ahead of it to assist its flight? Is the 2-dimensional V more efficient aerodynamically than some sort of 3-dimensional formation? Or is it just easier to stay in formation in 2 dimensions? For a short flight, geese take up a disordered 3-dimensional formation - it is not worth the time and trouble to get into a line or line or V formation. Some non-migratory species also fly in disordered 3-dimensional swarms for short flights. Would it be more efficient for a group of cyclists to move in a V formation rather than as a disordered group? (They are necessarily restricted to 2 dimensions.) Some fish also move in disordered 3-dimensional swarms. I think that is partly to confuse predators, especially considering the sudden turns some swarms make. But probably, also, the moving mass of water created by a swarm of fish assists all of them - albeit there is turbulence within the mass of water. - GloWorm
The V formation is indeed highly efficient, but for different reasons. If you look carefully, you will see that in addition to the position, the birds also synchronize their wing beats. This allows the use of the vortices generated by one bird to be used by the next bird. See [50] or [51]. --Stephan Schulz (talk) 16:34, 11 July 2009 (UTC)[reply]
That's interesting about synchronized wing beats. But wouldn;t a straight line formation be better for that? It seems that a V formation gives each bird the advantage of only one of its leaders wings. A straight line formation would give the follower the advantage of both the leader's wings. - GlowWorm. —Preceding unsigned comment added by 98.21.109.135 (talk) 16:53, 11 July 2009 (UTC)[reply]
The bird situation isn't the same as the 'drafting' situation with cars & bikes - it's about making it easier to generate lift - not to minimise drag. Isn't it the case that (seen from behind) a bird's left wing generates a clockwise vortex and the right wing an anticlockwise one. The bird behind it needs a clockwise vortex under it's right wing and an anticlockwise one under the left...so if they flew in a straight line, there would be no benefit. However if one bird positions it's right wing behind the left wing of the lead bird - and another puts it's left wing behind the lead bird's right - then they both get half of the benefit. This would lead naturally to the V formations we see. Alternatively - (but less likely), it might simply be that each bird desires to see where it's going...I don't think that's it though...I'm going with the clockwise/anticlockwise thing. SteveBaker (talk) 17:52, 11 July 2009 (UTC)[reply]
Totally anecdotal: When I've seen geese, etc., in a line, the line has been a "half V"—that is, they aren't flying exactly in the direction of the line, but as though the line were one side of a V with the other side missing. I've also seen formations in which there was only one or two birds behind the leader on one side and many more on the other side. I don't think I've ever seen a formation such as GloWorm describes: "a straight line of birds … lined in the direction of flight." Deor (talk) 02:23, 12 July 2009 (UTC)[reply]
Dirty Question II
I know this might come off as a joke, and it sorta...kinda is.
Yet at the same time I'm asking it with genuine curiousity, because I've never been able to get a direct answer for it.
To get into Medical School, you've gotta pretty much work your ass off (pun to be intended).
In most countries you usually have to earn a separate Bachelor's degree before even being eligible.
After four years, if you happen to have exceptional grades, and if you manage to score exceptionally well on your MCAT (or similar Standardized Test depending on Jurisdiction) you might actually have a chance to be accepted into a decent Medical School.
After several more years of working your ass off (see above), you finally earn your MD (Unless you flunk out or quit), allowing you to practice as a GP.
Sorry for the long intro, but here's the question: After all those years of hard work, once earning an MD, some, for reasons I cannot comprehend, opt to further extend their grueling studies, and forego several years of a GPs salary in order to pursue a specialty in proctology. (pun finally arrived at).
My question couldn't be simpler.
Why?
Is it a matter of supply and demand? Do proctologists earn far higher incomes than GPs as a reward for having to dedicate the rest of their lives to further humanity's understanding of the human anus?
Sorry again if this comes off as a joke, but I'm genuinely perplexed by this.
My wife reports that, after utilizing the services of a proctologist for less than an hour, upon seeing the bill, it is quite clear what advantages that particular speciality offers the doctor. She does report, however, that the services were worth every dollar... --Jayron32.talk.contribs22:55, 10 July 2009 (UTC)[reply]
Why not? On seeing every crevice of human anatomy in its naked glory, day in day out for 10 years, the anus, vagina and penis lose their 'eewwww- gross novelty value pretty quickly. A digital investigation of an anus is no more inherently "gross" than a digital investigation of a mouth. Yet no-one asks why would anyone choose to become a dentist.
I completely understand how the grossness would wear off "after ten years", thing is, the OP was talking about Med School Grads, not ten year vets.
WRT job satisfaction, how is saving the lives of colorectal cancer patients more personally rewarding than saving the lives of lung cancer patients?
I'm not quite sure what Rockpocket means to say when s/he uses the term "inherently gross". Alls I know is that it's the anus that releases what I would consider some "inherently" foul smelling matter, not the mouth.
If I were the newbie still not quite immune to the "gross" factor, I'd go for the lungs.
I'm with Jayron here, unless someone comes up with an even more sensible answer. Rockpocket's first response is based on a misreading of the question, and the second is logically flawed. 76.67.137.220 (talk) 01:52, 11 July 2009 (UTC)[reply]
The exact time isn't particularly relavent. Even after a couple of years of exposure, one gets immune to it. By the time you are in a position to specialize, you have seen all the shit you could imagine, and a fair bit more. You respond to my comment about inherent distaste with a subjective response: Yes, you consider it gross. Just because you do, doesn't mean everyone else does. That, if anything, is a logical flaw. Finally, rather than dismiss an answer on whether you consider is sensible or not, you could actually check whether it is accurate. Proctologists earn a decent salary, but (in the USA in 2008) it only comes in 17th in the list of best paid specialities, behind a lot more - what you would likely consider - less gross jobs. Go figure. Rockpocket03:11, 11 July 2009 (UTC)[reply]
Ah, after looking it up I see the phrase is used differently in the US. Our article is rather difficult to understand, though... --Tango (talk) 02:58, 11 July 2009 (UTC)[reply]
I once asked my urologist why he chose that particular speciality. He said that he had considered a few specialties before deciding. The reason he chose urology was due to the fact that the other doctors that he spoke to who were in the field already seemed like people that he would get along with best. There was something about the cardiac guys having a god complex from what I recall... It's been about four or five years... Dismas|(talk)05:16, 11 July 2009 (UTC)[reply]
Yes, you consider it gross. Just because you do, doesn't mean everyone else does.
Agreed! Perhaps I'm the only person on the planet who finds that shit stinks.
"Finally, rather than dismiss an answer on whether you consider is sensible or not, you could actually check whether it is accurate. Proctologists earn a decent salary, but (in the USA in 2008) it only comes in 17th in the list of best paid specialities, behind a lot more - what you would likely consider - less gross jobs. Go figure."
Precisely!
Go figure!
How does that help the OP in any way other than to repeat the question?
Go figure!
Q: Go, Wikipedia people, please figure out why certain Med students decide to go into proctology because it just plain doesn't make sense to me.
A: Go Figure!
Q: Why do certain brilliant med students decide to specialize in the the shit hole?
The OP asked about Med School Grads. Your first post spoke of 10 year vets and was therefore wrong and potentially misleading. Please remove it. Thank you. 76.67.137.220 (talk) 08:07, 12 July 2009 (UTC)[reply]
Let's try. Possibly partly because of the yuk factor, or certainly a lack of glamour factor, fewer doctors choose proctology, therefore there is less competition for patients, therefore possibly higher income. There is also the social life consideration, shared with opthalmology, dermatology, cosmetic surgery, dentistry etc., that some specialities are unlikely to involve emergencies, so make a comfortable settled life possible. Cardiology, neurosurgery, orphopaedics etc. can involve unexpected call-outs and extremely long hours. Some of these necessarily involve large staffs and many assistants, therefore working at or out of a hospital. Others can be conducted as private practice from own rooms, with minimal or no surgical theatre space or gazillion dollar equipment required. So proctology allows a good living with minimal set-up costs for private practice, and "normal" working hours without emergency calls; an added bonus is the lower likelihood of being approached for free medical advice at social functions than a dermatologist or plastic surgeon might face. - KoolerStill (talk) 16:07, 11 July 2009 (UTC)[reply]
I know a few people who specialize in a certain field because of some prior tragedy related to it. If one has a family history of a certain type of cancer, one might choose a life goal to treat it in some way. DMacks (talk) 19:56, 11 July 2009 (UTC)[reply]
"Tying up" is a kind of muscle spasm - aparrently it's caused by overwork and chronic tension in the muscles. Basically some form of lactic acid problem. SteveBaker (talk) 23:57, 10 July 2009 (UTC)[reply]
Huh? It doesn't explain the cause, just talks about whether or not it's related to the vehicles' suspensions. --Anonymous, 05:41 UTC, July 11, 2009.
"when vehicles move above a critical speed, that depends on the properties of the vehicles and the road surface. If all the vehicles move below their critical speed the road will remain flat, but if they move faster, ripples will slowly grow and move in the direction of the vehicles." Regards, --—Cyclonenim | Chat 09:44, 11 July 2009 (UTC)[reply]
Exactly. It just describes what happens, not why. --Anon, 10:01 UTC, July 11.
Quote from the German wikipedia "A depression in the road causes intense ground contact (?) between the wheel of the vehicle and the road surface. When moving out of the depression the wheel moves upward like on a ramp and briefly jumps to cause a new depression." Bei dem Herausfahren aus der Vertiefung bewegt sich das Rad wie auf einer Rampe nach oben, um nach einem kurzen Sprung eine weitere Bodenvertiefung vorzubereiten.71.236.26.74 (talk) 11:19, 11 July 2009 (UTC)[reply]
Vehicle suspensions are harmonic oscillators. Each vehicle tends to resonate with the depressions and bumps left by previous vehicles. The effect over time is erosion in the road of ripples corresponding to the average resonant frequency of vehicles. Cuddlyable3 (talk) 22:55, 11 July 2009 (UTC)[reply]
Although the article does not say this, I am firmly of the opinion that a light rain -- enough water to partly fill the holes -- is the primary "exacerbater" of the condition once it starts for other reasons. Water gathers in the "valleys" and softens the dirt; the next vehicle along splashes the mud mixture out, usually to the sides, making the valleys even deeper. --DaHorsesMouth (talk) 22:19, 12 July 2009 (UTC)[reply]
It's fairly simple. We can tell in what time periods wildfire occurred by looking for charcoal in the fossil record. The record shows that wildfires first occurred in the Late Silurian and have occurred ever since, with the (apparently controversial, though a glance at the source doesn't indicate what the controversy is) exception of a period in the Late Devonian (the source says middle to early late) in which there is no charcoal in the fossil record, so presumably no wildfire, so presumably low atmospheric oxygen. Algebraist03:36, 11 July 2009 (UTC)[reply]
That is not entirely clear. The controversy is about the lack of charcoal in the Late Devonian, but whether the dispute is over whether this lack exists at all or over some more subtle point I can't tell. Algebraist03:46, 11 July 2009 (UTC)[reply]
If you have looked for evidence and found none, then that is evidence of absence... Absence of evidence is only nonevidence of absence if the evidence is absent because you haven't actually looked for it. Maelin (Talk | Contribs) 11:39, 12 July 2009 (UTC)[reply]
Not logical Maelin. The other possibility is that your method of search is fallible. In real science, this is often the most likely possibility. alteripse (talk) 19:09, 12 July 2009 (UTC)[reply]
It certainly is logical. If the hypothesis predicts that you make a particular observation, and you in fact make a contrary observation, that is evidence that your hypothesis is false. When I open my pantry and I look for the bread and I conclude, "I cannot see any bread in the pantry", that is good evidence that there is no bread in the pantry. Contrast this with simply not opening the pantry at all and then saying "I cannot see any bread in the pantry". Absence of evidence is evidence of absence, provided you have looked for the evidence and found it to be lacking. Maelin (Talk | Contribs) 05:40, 13 July 2009 (UTC)[reply]
Fire particles
I remember reading something a couple years ago about an old theory (1500 - 1600s perhaps?) that fire was the release of particles from a substance. And when, for instance, a piece of wood was burned, these particles were no longer present in what remained. What is the name of the particle? Does this ring a bell with anyone? I thought I read it here but I don't know if I'm mis-remembering since Google searches for things like Fire Particles hasn't turned up anything familiar. Dismas|(talk)03:45, 11 July 2009 (UTC)[reply]
The neat thing about the phlogiston idea was that the particles had negative mass - so when you light a fire with (say) some wood, the phogiston from the flames enters the wood and reduces it's mass - thereby reducing it to ashes. Similarly, when you boil water - the water level drops. When you sweat - the water evaporates, taking with it some of the phlogiston which is why you feel cooler. It's quite a clever idea given the very limited experimental evidence of the time...but it requires some complicated logic to explain the fact that heating mercury (which produces mercuric oxide) produces something that's actually heavier than what you started with - despite all of the phlogiston you poured into it. SteveBaker (talk) 04:21, 11 July 2009 (UTC)[reply]
No, phlogiston is present in flammable materials and leaves them when they burn. That's why you end up having to assign it negative mass when you discover (for example) that burning metals gives you more mass than you started with. I'm pretty sure no-one thought it came in particles, either. It was more a fluid of some sort. Algebraist04:25, 11 July 2009 (UTC)[reply]
Our article mentions it has no mass. So why should negative mass be assigned, or why would mass increase when phlogiston leaves an object ? Rkr1991 (talk) 08:52, 11 July 2009 (UTC)[reply]
Well, I think Algebraist just answered both of those...It has negative mass because when it leaves an object, the object becomes heavier (burning substances which become heavier after a reaction are thus explained this way). The real reason an object becomes heavier after a reaction is because it has more mass (obviously not true for all reactions); but they didn't know that at the time. Vimescarrot (talk) 09:12, 11 July 2009 (UTC)[reply]
You don't get it. The article says it has zero mass, not negative. That is the main theory. When contradicted, some scientists suggested that it may have negative mass so that it may explain things like the burning of Magnesium. Yet, it would not work. The way Algebraist puts it, it sounds as if the main theory itself suggested that Phlogiston has negative mass. But according to the article, that was just a view of some of its later proponents. Rkr1991 (talk) 13:05, 11 July 2009 (UTC)[reply]
At the time the theory was created, most things that were burned contained Hydrogen and Carbon, and those were the parts that were oxidized into H20 and CO2, i.e. into invisible and odorless gases that vanished. Thus, if you burned wood, or tallow, or lamp oil, or paper, the visible remains (the ashes) are indeed lighter than the original substance - and what you lost was the hypothetical Phlogiston. This is not true for substances that create only solid ashes, like several metals. To apply the Phlogiston theory to e.g. magnesium, you need to postulate a negative weight (and thus, I assume, different kinds of Phlogiston). --Stephan Schulz (talk) 12:55, 11 July 2009 (UTC)[reply]
Two and a half. The linked article has a detailed history of it. Our whole discussion here is about the theory as it was and its correctness as far as they knew at the time. It's actually still a viable discussion topic as an example of how science makes testable hypotheses and changes or discards theories as new evidence becomes available. DMacks (talk) 09:38, 11 July 2009 (UTC)[reply]
One million square kilometres of sea ice from this area could disappear by September, including the Beaufort sea and areas farther northwest.
Hi. As I was in an airplane travelling over what was presumably north of the Beaufort Sea, I saw a glory over the sea ice. The sea ice was riveted with cracks and melt ponds, and perhaps the whole section will melt by September (about 1 million km2 of it; by the way are there any predictions for minimum Arctic sea ice extent for this year?). However, that's not the point. Now, presumably in the centre of the glory should be the plane's shadow. However, that's not quite what I saw.
Now, I didn't take a picture, but it was approximately midnight local time, but there was sunlight. It was the Arctic midnight sun. I was travelling approximately west, and the sun was near the front-right area of the plane. I was looking from the left side of the plane, and the glory was slightly behind the direction facing from the left (therefore, the Sun was to the northwest and the glory to the southeast). However, the shadow of the plane was a strange shape. It started in the centre of the glory, but then extended back almost parallel to the plane, very slightly pointing away from it. There were no wings visible in this shadow; it was faint and was basically a thin line that extended farther back on the ice than I could see. Was this the shadow of the plane, and if so, how did it form such a shape? The sun was presumably very low on the horizon (15 degrees according to Yoursky); the glory was probably only visible for about 10 minutes, while Arctic daylight on the aircraft lasted seven hours (we kept just prior to midnight local time during the whole trip).
Now, here's an aside. How does one identify the difference between cloud iridescence and irisation? Is it the type of cloud, the dominant colours, the pattern of the colours, how far away it is from the Sun, the season, etc? Thanks. ~AH1(TCU)08:01, 11 July 2009 (UTC)[reply]
About the strange shape of the shadow: since the sun was at the plane's one o'clock to two o'clock and very low on the horizon (as is always the case with midnight sun), the shadow projected onto the glory was identical in shape to the plane's view from that angle, so it's only natural that the wings would not be visible (the right wing was very likely being projected onto the fuselage and the left wing obscured by it). I'm not really sure why it was stretched out "farther back than you could see"; it could have had something to do with the curvature of the plane's window, or it could have been something else.
76.21.37.87 (talk) 08:28, 11 July 2009 (UTC)[reply]
As for your second question, I'm not really sure, but the Wikipedia articles say that cloud iridescence is usually caused by light refraction/scattering by water droplets/ice crystals/smog particles (similar to a rainbow/glory/halo), while irisation is a less common phenomenon caused by diffraction and mostly seen in stratospheric nacreous clouds. However, it appears to me that there's also some overlap between these two terms, so it wouldn't surprise me if I found out that they are interchangeable. FWiW
76.21.37.87 (talk) 09:09, 11 July 2009 (UTC)[reply]
The shadow of your own head (or the shadow of the part of the plane where your head is situated) will be precisely at the center of the glory...which it sounds like it was. The other parts of the plane's shadow could be anywhere...the extreme distortion of the shadow comes about because the sun was so low in the sky - and that causes very distorted shadows. SteveBaker (talk) 17:27, 11 July 2009 (UTC)[reply]
can i say so
what kind of cooling arrangments do american steel manufacturers use? They tag a high steel price.I suspect some kind of air+water mixture type cooling.Kindly let me know.
the process varies depending on what the steel will be used for. Generally, in the case of Canned food or sheet metal, a process called Cold Rolling Is used, in which case they deform the metal by passing it through a roller that has a temperature lower than its recrystalization process allows. Then again, another process known as Quenching Has been used which increases the durability and strength of the metal.
They don't use mercury because the vapors generated would be highly toxic. They do, however, use water, oil (which stinks like you wouldn't believe, but is not very harmful), and sometimes silicone-based liquids for quenching of steel. FWiW
76.21.37.87 (talk) 02:35, 13 July 2009 (UTC)[reply]
Orbital Capture of Moons
Can someone explain to me how a large moon could just be flying through space and suddenly captured by a planet? (fyi, I know most moons aren't formed this way) This doesn't make sense to me as whenever spacecraft want to enter into orbit of a distant body they need to burn off excess energy at the periapsis to circularize the orbit. Spacecraft can also utilize atmospheric drag, assuming the planet has one, and I suppose the moon could skim through the atmosphere but it seems the odds of the resulting orbit being stable would be very low. So how does a planet without an atmosphere capture a moon? TheFutureAwaits (talk) 11:21, 11 July 2009 (UTC)[reply]
Atmospheric drag is not a possible mechanism for capture. The effect of "burning off energy at the periapsis" is to convert an open, hyperbolic orbit into a closed, elliptical one, or if the orbit is already elliptical, to lower the apoapsis. (In a two-body situation, once you have an elliptical orbit, it always continues to pass through the point where a force was last applied, i.e. the atmosphere.) Atmospheric drag could "capture" an object into collision with the ground, but not into an orbit above the atmosphere. --Anonymous, 20:29 UTC, July 11, 2009.
Yes, that's it. The involvement of a third body is required. --Anon, 20:29 UTC, July 11.
I am no physicist, but I assume the energy is needed by a spacecraft if it wants to get into a circular orbit. Without that, it, or a potential moon, would get into an elliptical orbit. I believe that over time (very much time), that would get 'flattened' more and more until finally it approaches a circular orbit, but I'm not sure why that is. DirkvdM (talk) 13:20, 11 July 2009 (UTC)[reply]
Well, the conservation of momentum laws apply. If the planet were somehow nailed down and unable to move - it would indeed be impossible for a moon or a spacecraft to get 'captured' into a stable orbit. But planets are not nailed down - so conservation of momentum allows for the COMBINED momentum of planet and moon/spacecraft to be conserved because each of them cannot be considered as a "closed system". To envisage this, consider the planet and the moon as being roughly equal in size - it's not much of a stretch to imagine them both winding up orbitting about a point midway between them - and together moving off from the planet's starting point at about half the speed of the incoming moon. SteveBaker (talk) 17:02, 11 July 2009 (UTC)[reply]
This does not seem to help with "envisaging" the point that there needs to be a third body involved somehow. --Anon, 20:29 UTC, July 11.
If there were only the planet and the moon then you are absolutely right, you can't be captured without a rocket burn. With a many body problem, however, it is far less simple. You can get all kinds of complex interactions that can result in capture. Once you've got a periodic orbit tidal forces can circularise it. --Tango (talk) 17:40, 11 July 2009 (UTC)[reply]
Yes, that's it. --Anon, 20:29 UTC, July 11.
H and O in H2O
I was wondering, say the bond between H and O in H2O could be broken safe and economicaly, how much of each would a liter of Water contain. Using it as a fuel, would it be necassary to carry many, heavy lites of water, making it useless as a fuel for say a plane ?41.15.144.2 (talk) 11:45, 11 July 2009 (UTC)[reply]
The molecular weight of water is 18, hence a liter of water contains 1000/18=55.55 mol of water. This means it contains 55.55 mol of H2 and half that of O2, or, in other words, about 1300 l of H2 and 650 l of O2 at normal conditions. Unfortunately, you cannot carry this around for fuel in the compact form of water, since the energy you get from burning it is exactly the same you need to split it in the first place, and you will have losses either way. --Stephan Schulz (talk) 11:58, 11 July 2009 (UTC)[reply]
If you use it as fuel, of course you don't carry it in the form of water, but as hydrogen (the oxygen you get from the air, so you don't have to carry that). In a car, the large volume is a problem, so it has to be compressed, but for a plane the fact that hydrogen is light can be a huge advantage. Airships sometimes use hydrogen for lift. But as you say, you can also use that hydrogen for propulsion, so you get two for one. Of course, as you burn hydrogen, you lose lift, so you'll need more hydrogen-power to keep the plane in the air. But still. I wouldn't be surprised if this idea has already been worked out in more detail, but I have never heard of it. Hydrogen economy appears to mention planes just once, in the intro, so no help there. DirkvdM (talk) 13:04, 11 July 2009 (UTC)[reply]
Burning the lifting gas would require ballast to be released, reducing the range of the airship. Conversely, burning gasoline or similar fuels, as in most airships, causes the vehicle to get lighter during the cource of each flight and requires some of the lifting gas to be released, which also reduces the range (and adds to the cost). In the airship Graf Zeppelin they avoided both problems by burning a gaseous fuel that was about the same density as air: Blau gas. (They carried some gasoline as well, to burn in case they wanted to lighten the airship gradually.) I presume the reason other airships did not adopt this was that the volume occupied by the Blau gas was inconveniently large. --Anonymous, 20:42 UTC, July 11, 2009.
Oh, there is a Hydrogen airplane article. To my surprise, this doesn't mention the lift advantage and says the hydrogen should be pressurised. Of course, a sufficient amount of uncompressed hydrogen would make the airplane rather big, which would not be good for the aerodynamics. DirkvdM (talk) 13:13, 11 July 2009 (UTC)[reply]
To be VERY clear - (as Stephan points out) - the laws of thermodynamics require that it takes more energy to pull the water apart into H2 and O2 than you can possibly get back from recombining them. So you cannot use water as a "fuel"...that a flat out guaranteed: "NO!" Some people suggest that using electricity to split the water and then burning the gasses conveys some advantage - but that too cannot be more efficient over (say) just using the electricity to drive electric motors. Moreover, since the result of burning hydrogen with oxygen is just water again - you could capture the exhaust from such a vehicle and put it back into the water tank. That makes water the "working fluid" - and not the "fuel". However, thermodynamics is a harsh mistress and there is no possible way to make an energy "profit" while doing that.
So "water as a fuel" is quite utterly "busted". Sadly, there are a lot of people out there (like these evil bastards and these nut-jobs and these scam artists and these conmen...and many, many more) who'd very much like to take your money by selling you things like that...but please don't believe a word they say! They are all liars, cheats and con-men - the laws of thermodynamics say so.
To note some possible caveats to Steve's rant, though, there's a possible rationale to using water (well, the hydrogen component, as noted above) as fuel. If you've got a clean plentiful source of grid electricity, then you may not care about the thermodynamic losses of cracking water on an industrial scale. That hydrogen supply could then serve as a clean car fuel that's easily refilled -- while it's less efficient than an electric car, it doesn't suffer the range limitations. Note that this is different from the scams noted above, though -- it relies on a clean power source that we don't yet have at the scale required. "Clean" is included because we could do this now with coal plants, but the greenhouse emissions make it a non-starter. Fix that, though, and the rest becomes pretty simple to implement. — Lomn17:47, 11 July 2009 (UTC)[reply]
Steve is exactly right. There is no scenario under which the water can be used as a fuel§; any attempt to produce excess energy from breaking and reconstituting the hydrogen-oxygen bond would constitute a perpetual motion machine, whose existence is ruled out by the laws of thermodynamics and is not simply a matter of developing an advanced enough technology.
The scenario Lomn outlines is that of using hydrogen as a fuel, which of course is completely reasonable. The fact that water may be used as the source for hydrogen, doesn't make it a fuel though - at least, if we are using that word in the conventional sense; note that conmen often assign non-standard meanings to scientific terms in order to hoodwink lay customers/investors (see Stanley Meyer's water fuel cell for one such scientific and financial scam; ).
§: Here, I am specifically referring to dissociating water into hydrogen and oxygen, and then burning the released hydrogen to produce energy. Of course, falling water can be used to generate electricity, and water is used in a steam engines, but in neither of those cases do we refer to it as the fuel. In addition, there are several exothermic reactions involving water that can in principle be used to run a generator; in such cases water could validly be called a fuel, but I don't think there are any such reactions that are of any practical importance for energy generation. Abecedare (talk) 18:28, 11 July 2009 (UTC)[reply]
Sure - you can make hydrogen from water (at some cost in electricity or whatever) and use THAT as a fuel. But it's (a) not an efficient process and (b) not using water as fuel. Water is the 'ashes' you get left over after burning hydrogen..it has no energy left to release - the only way to get energy out of water - is to put more energy into it first. Once you do that (eg by boiling it in a steam engine - or splitting it into H2 and O2 in an electrolysis cell) - you can take back some of the energy you put in...but you don't get it all back. That doesn't make steam engines or hydrogen manufacturing plants useless - using energy in a more convenient form is valuable. Hydrogen powered cars make a certain amount of sense.
If we somehow manage to build enough windmills or get fusion reactors working - they'll be the way forward. But we have to be very VERY clear that we aren't getting energy FROM water - we're putting energy INTO water. Which is the complete opposite of what these evil conmen are claiming. SteveBaker (talk) 18:30, 11 July 2009 (UTC)[reply]
Sadly, about a year ago, Reuters got sucked into doing a story on Genepax, who had supposedly developed a water-fueled car.[54] You’d figure a big news service like Reuters would have science editors who would know better. Red Act (talk) 20:03, 11 July 2009 (UTC)[reply]
Sad to see Reuters fall into the trap. Such scientific illiteracy is usually restricted to local TV news reports, which always seem to include the claim that the military (or NASA) is studying the technology. Abecedare (talk) 20:30, 11 July 2009 (UTC)[reply]
Well, what do you expect from Reuters? They're just reporters, how scientifically literate could they be, anyway? You want scientific literacy, go with Scientific American or with Popular Mechanics.
Whilst on the subject of water as fuel - there have been attempts to inject water into combustion engines along with the fuel - reason being that the water is vaporised when the fuel combusts - converting heat to 'pressure' (as steam) - note that the water is not a fuel in this case. The high heat capacity and enthaply of vaporisation of water would seem to be disadvantages here...
The reason to do it is to increase the energy efficiency of a combustion energy by adding a 'filler' that can convert heat to pressure (usable as work) by the engine.
An electric motor can operate as a generator and vice versa. Why then do automobiles have separate dynamo and starter motor? Combining them saves many mechanical parts such as solenoid, starter gear, and pulley wheel. The current is much higher during the brief time a starter operates than in the dynamo that runs continuously, so they probably need separate windings. The Isetta article says BMW used such a combined unit in their Isetta 250 microcar. Cuddlyable3 (talk) 22:29, 11 July 2009 (UTC)[reply]
Possible reasons that occur to me:
If the separate starter motor fails, you can still bump-start the car in order to drive it home/to the garage/whatever (as has happened to me); if the two are a combined unit, then such a failure might make the car undrivable.
The reliability of a (presumably more complicated) combined unit might be appreciably less than that of two simpler separate units.
A combined unit is likely to be more expensive than either of the two separate units, so in the long run, repair/replacement costs would likely be higher.
A combined unit is presumably smaller and lighter overall than two separate units, and its use in the tiny Isetta 250 microcar was presumably to save space and weight; in a normally sized car the space and weight saving would probably be insignificant, so would not outweigh the disadvantages. 87.81.230.195 (talk) 23:41, 11 July 2009 (UTC)[reply]
The starter motor is more powerful than the alternator. "Cranking" a car consumes electrical energy faster than an alternator stores it. One rotary device could doubtless be designed to serve both roles. A rotary electrical device powerful enough to crank the engine might be inefficient when spun continuously as an alternator to provide steady state power. It is certainly something to look into. I seem to recall that General Motors was looking into using one motor/generator for this purpose, shutting down the internal combustion engine when the car stopped at a red light, then restarting it when you wanted to go, with a drive belt connecting the gas engine and the motor/generator. Edison (talk) 03:51, 12 July 2009 (UTC)[reply]
How does the mortality rate, duration, and severity, of being ill from Swine flue compare with that of being ill from ordinary flue, without any drug treatments in either case? In the UK people with swine flu are given Tamiflu, so its difficult to gain an idea of what its like untreated. I understand that in the US, most people are not being given Tamiflue. I understand that most people start getting better after two or three days - previously I would have called such a short illness a cold rather than flue. I thought flue was suppossed to last more like a fortnight (which translates as two weeks in American English). Thanks. 78.151.124.180 (talk) 23:49, 11 July 2009 (UTC)[reply]
It's not actually much different to ordinary seasonal flu: as our article notes. However, it is considered by some to be "unstable" and therefore more likely to mutate. There are some reports that it is a devleoping resistant to anti-virals (such as Tamiflu). This could, perhaps, bring some debate regarding the routine administration of Tamiflu to all sufferers, rather than restricting it to severe/problematic situations. Gwinva (talk) 00:03, 12 July 2009 (UTC)[reply]
And just to be clear, flus (influenzas) and colds are not distinguished by their duration: they have different viral agents, as the articles make clear. Indeed, our cold article states that the cold typically lasts 7-10 days (up to three weeks!). Matt Deres (talk) 01:42, 12 July 2009 (UTC)[reply]
To give you an idea of how swine flue is viewed in the states: A few weeks back when swine flu was all over the news, the local government for my state (Vermont) was telling people who thought that they may have swine flu to stay at home. They recommended only the elderly, very young, and those with compromised immune systems to actually go see a doctor. Otherwise healthy people were asked to just stay at home and treat themselves as though they had any other cold or flu. Dismas|(talk)04:28, 12 July 2009 (UTC)[reply]
If you use the Google 'street view' camera - it's obvious that they are Gas holders. Large cylindrical tanks which rise within a circular frame when filled with gas - and whose weight pressing down on that gas ensures that there is sufficient pressure to push it through the local pipework to people's homes and businesses. SteveBaker (talk) 01:14, 12 July 2009 (UTC)[reply]
"In the speculative nonfiction series Life After People it is said that, after a million years of travel in interstellar space, the Voyager probes will be so heavily damaged from micro meteor impacts that the disks will become unreadable."
Because there is no mention of this beyond the fiction section i wanted to know if there was any truth to that statement.--SelfQ (talk) 01:25, 12 July 2009 (UTC)[reply]
The probes are so far from the sun now (well outside the Kuiper belt) that the amount of debris is almost zero - the odds are extremely good that these records will last for well over a million years. SteveBaker (talk) 01:54, 12 July 2009 (UTC)[reply]
On a related note, how are the disks packaged? It seems to me that the most likely scenario for an alien civilization to get the disks is if the Voyager actually collides with an inhabited planet (therefore, a planet with a breathable atmosphere), with all the consequences that this entails. And you can't very well read a bunch of disks if they've burned up during reentry, can you?
The discs are packaged in a protective cover, shown here. Micrometeorites would have to penetrate this cover to damage the actual recording medium. Nimur (talk) 03:38, 12 July 2009 (UTC)[reply]
It could enter the atmosphere of some alien planet and be burned up. The last meteor to enter the Earth's atmosphere might have been a space probe from some wonderful planet, complete with examples of their music, poetry, and science, that would have enriched our lives. But another scenario is that 100,000 years from now, Voyager is detected by radar and telescopes of another world, and a robot space tug takes it to their scientists for analysis. They play the record, look at the pictures and marvel that there were once such people as us, though we be tribal killer apes who may destroy our race. See also the Star Trek Next Generation episode wherein Picard is the particular target of such a probe from a vanished race and is forever changed as a result. See The Inner Light (Star Trek: The Next Generation) (took some searching to find it). Edison (talk) 03:40, 12 July 2009 (UTC)[reply]
Not within the next million years. Neither Voyager probe is aimed towards any particular star - and the odds of just happening to fly close enough to one are astronomically small. There is no possible way they could enter the atmosphere of a planet within that short an amount of time. Also, the Voyager probes will run out of power in about 15 years from now - beyond that, they would pretty much be indistinguishable from a rock as far as alien telescope users would be concerned...but since the closest they're coming to a star in the next 100,000 years is 1.6 lightyears - it's really not likely (and probably outright impossible) for an alien telescope to spot them by chance. The universe is a VERY big place and these are incredibly TINY probes. They'll most likely still be heading off in a more or less straight line without noticable deterioration for a few billion years...they'll probably outlast us, and our planet. SteveBaker (talk) 04:02, 12 July 2009 (UTC)[reply]
A more advanced civilization might note its approach. It might cross the path of one of their spaceships. By the way. did you read the article about the Startrek episode, which had the topic of a civilization ending out a probe so someone somewhere would remember them? Edison (talk) 04:52, 12 July 2009 (UTC)[reply]
I find it interesting that SteveBaker pretty much rules out the likelyhood of an alien civilization finding either Voyager probe. I never realized that you were that well versed in future alien technologies. ;-) Dismas|(talk)05:32, 12 July 2009 (UTC)[reply]
You don't have to understand their technologies - you only have to consider the fundamental limitations imposed by the laws of physics and statistics. If you take Dragons Flight's number (below) of 1-10 billion years to get within 60 astronomical units of another star - then consider the likelyhood of detecting something about 2 meters across and weighing 750kg at a distance of 60AU when it's in a totally unexpected (indeed random) position and moving in a random direction. At that kind of distance, the amount of light it would reflect will be truly negligable - it's nuclear power plant will have long ago run down - so it certainly won't be emitting radiation or heat or light or radiowaves of it's own. At 700kg you aren't likely to be able to detect any gravitational disturbance due to it's mass. What conceivable technology could spot it? The extreme limits of our ability to observe objects out that far is to detect Kuiper belt objects down to maybe 100km in diameter! Voyager (at around 2m in diameter) is going to be more than two billion times dimmer! The probability of an alien detector being hit by even one photon reflected by Voyager is quite negligable - so the detector would have to be tracking it for a long time, accumulating these occasional stray photons from it - but since it's coming from a random direction and at a random speed - the probability of the alien detector happening to track it by pure chance is essentially zero. Even if they did happen to pick up some tiny amount of reflected light from it - aside from it's somewhat unusual metallic composition - it's going to be utterly indistinguishable from any other tiny Kuiper-belt type of object - of which there are trillions and trillions to choose from. Why would they bother to investigate this one? Everything says that this craft would be quite impossible to detect with any halfway credible probability. If a similar alien craft entered our solar system - and even if it came close enough to graze our atmosphere - we'd never notice it. If it actually entered out atmosphere - it would burn up before we could tell what it was. There is literally no way for us to detect an alien craft that size. SteveBaker (talk) 15:06, 12 July 2009 (UTC)[reply]
A random object travelling through space ought to intersect a star system (within 60 AU) about once every 1-10 billion years. Incidentally, that number suggests the sun may have had a relatively close approach by some other star at some point in its 4.5 Gyr lifespan. It will take Voyager a long time to find another star merely by chance. Dragons flight (talk) 10:34, 12 July 2009 (UTC)[reply]
On the other hand, destruction of the disks might not be such a bad thing for us. Consider the inevitable consequences that have occurred on earth every time a culture encounters a vastly more advanced culture, and perhaps the person who characterized that Voyager message as the "single most reckless act in the history of our species" has a point... alteripse (talk) 19:04, 12 July 2009 (UTC)[reply]
Pain
Congenital insensitivity to pain suggests that the sensation of pain can essentially be isolated from other sensations (with the exceptions of temperature). Does this have any analgesic applications? Is their any method of pain management (obviously one dealing with intense chronic pain) that attempts to "sear" the nerves responsible for pain?
Well, there are many methods that temporarily block the nerves responsible for pain: some of the ones that you're likely to be familiar with are painkiller shots to numb your jaw before a dental procedure such as a dental filling or (if you got really bad teeth) a root canal; or (if you're a woman who's had kids), an epidural block to reduce the pain of childbirth. As for permanently "searing" or deactivating the nerves responsible for pain, I haven't the foggiest.
76.21.37.87 (talk) 04:23, 12 July 2009 (UTC)[reply]
Sorry to ask frequently asked things.
But I have two.
The first is:
I know if two observers start from the same inertial frame, accelerating and decelerating alike in opossite direction, experience the same time of inertial motion, and comes back to where they started, time dilation for both is the same (because everything is symmetrical).
But while both are in inertial motion, each observe the other's time delay, and to compensate for that, the time for each (not the other) must delay during acceleration.(I don't think gravitaional time dilation quickens the other's time.) But the other's time does not delay the same amount? If it delays, special relativistic time dilation is not compensated.
The second is:
In the same situation, but changing only the duration of inertial motion for both, total special relativistic time dilation increases. What compensates for the adittional special relativistic time dilation? Gravitational time dilation has "vertical" distance h in the formula to calculate the gravitational time dilation. I'm not sure, but acceleration at differently distant point (even if the acceleraion is the same) causes different time dilation? And that equals the difference of special relativistic time dilations?
Like sushi (talk) 04:38, 12 July 2009 (UTC)[reply]
You seem confused. There is no need to include gravitational effects in any of your examples since there is no gravity present. Acceleration is equivalent to a gravitational field only locally which is not the case here since there are two observers with an arbitrarily long space-like distance between them in your examples. When your observer accelerates it jumps from one reference frame into a different reference frame with a different set of simultaneaties. It is even possible that a distant event that was considered already past before the accelaration becomes a future distant event after the accelaration. No gravitational doppler shift (a better term than time dilation) can do that. Dauto (talk) 05:11, 12 July 2009 (UTC)[reply]
"Acceleration is equivalent to a gravitational field only locally" and we are dealing with "observers with an arbitrarily long space-like distance"? But if the motion of both are symmetrical,they would return to the point they started, and at the time they have just returned to the point they started and to the same reference frame, the traces of both are fully in the light cone of both. So everything is not "spacelike" at the time?
You are saying that the other is out of the light cone when the acceleration takes place? That is impossible (at least for an observer to see, because the skirt of light cone expands faster than the speed "the other" is observed to recede).
I think what you're saying is this: if two people travel in a perfectly symmetrical way then when they meet again the elapsed time must have been the same for both (by symmetry). But that's inconsistent with each one seeing the other's clock run slower. The answer is that they don't see the other's clock run slower, they see it run sometimes slower and sometimes faster, with the average speed over the whole trip being the same as their own. The observed speed of the clock is determined by the Doppler shift factor, , not by the time dilation factor, . The latter is rarely relevant in physically meaningful situations. -- BenRG (talk) 08:59, 12 July 2009 (UTC)[reply]
Well, I have thought about it, and using the formula , there is still time dilation observed in the case each recedes and approaches with the same speed, because observed time dilations are reciprocal to each other, adding them does not (at least always) result in no dilation.
Is there a Board of Trading where all agro products are traded? So far, I only found the more important like coffee, rice and such stuff. --Quest09 (talk) 11:08, 12 July 2009 (UTC)[reply]
OR Some (most?) vegetables don't get traded by boards of trading because they are grown on contract. I.e. depending on company rules/contract terms, a company like Green Giant will give the farmer the seeds, the fertilizer and if required pesticides (or issue rules for "organic" produce) and will come pick up the harvest with their trucks right from the field. They'll process and package the produce in their facilities and deliver to their distributors. Smaller non-contract producers will sometimes make contracts directly with local supermarkets. Restaurants and small markets pick up produce at local Farmer's markets sometimes.71.236.26.74 (talk) 20:48, 12 July 2009 (UTC)[reply]
Why do men and women exist? (evolutionary biology)
This might seem like a simple question, but I still can't figure out the answer. Evolution of sexual reproduction gives some plausible reasons for the development of sexual reproduction, in the sense of reproduction requiring more than one individual. But why are we and many other species not hermaphrodites (like Earthworms and plants)? After all, this seems like an advantage to me: a hermaphrodite can reproduce both as a male and as a female, thus increasing its reproduction chances. --filip (talk) 11:21, 12 July 2009 (UTC)[reply]
An earthworm has been around for a long time. It hasn't evolved much. This is one of the reasons for it. Having two sexes increases the chances for evolution and diversity. Rkr1991 (talk) 11:33, 12 July 2009 (UTC)[reply]
Expanding a little on Rkr1991, some creatures (eg aphids) will even reproduce by parthenogenesis at times when food is plentiful, making an immediate supply of identical creatures to consume the food. Later they will reproduce sexually to increase their diversity. Hermaphrodites will turn into female to take advantage of good conditions, as one male is enough to impregnate many females. This type of arrangement is suitable where quantity of population is needed for species survival. I all these cases the young are produced and left to their own devices.
In higher animals, much of survival depends on the (few) young being well cared for and educated, over long periods of time. This makes a variably large number of females a disadvantage, over a fixed smaller number having the permanently female characteristics needed for the nurturing of the young. In other words, we don't come in two sexes to be able to conceive more young, but to be able to nurture to maturity the few young that we do conceive. - KoolerStill (talk) 12:19, 12 July 2009 (UTC)[reply]
The benefit of not being hermaphrodites is that there are adaptations in the two sexes that make child rearing more efficient. For example, if we were hermaphrodites, we'd all have to have all of the baby-making apparatus - mammaries, womb, fallopian tubes, extra-large hips, monthly periods, etc. Since human children cannot be abandoned to fend for themselves at birth (as is the case with the offspring of hermaphroditic species) - it takes a minimum of two individuals to care for the child - one to stay home and look after it - the other to hunt the mammoth for supper. The one who is hunting the mammoth is more a more efficient hunter because he doesn't have to carry around all of that baby-rearing stuff. Of course, in reality - the split came a very long time ago when some hermaphroditic ancestor of all non-hermaphroditic animals evolved to have two different sexual morphologies - we would really have to ask the question as to why the change was most beneficial for THAT creature - which is tricky because it's unlikely that we know precisely when that happened and why. SteveBaker (talk) 14:31, 12 July 2009 (UTC)[reply]
Steve, that explanation applies to very few species, so clearly is not the explanation. It also smacks of 'Man, the mighty hunter' anthropology, which surely was discredited years ago because it doesn't really make sense? 86.140.144.220 (talk) 18:28, 12 July 2009 (UTC)[reply]
Agreed. Steves explanation, especially the part about having a womb and boobs making someone a less efficient hunter is a pile of steaming bs.
bs or not (ok bs) - 2 sexual organisms tend to be(are) higher up the food chain - thus a grain of truth
The latest explanation, for which there is some recent experimental evidence involving sexy & unsexy snails (actually sexually and asexually reproducing) is that the main benefit of sexual reproduction is parasite protection because a greater genetic variety of individuals is generated with each generation. Far more individual variation is provided by recombination of chromosomes than by single codon mutations. alteripse (talk) 18:58, 12 July 2009 (UTC)[reply]
That explains the point of sexual reproduction, which the OP already said he understands, but I don't see how it relates to the actual question: what's the point of some snails (or humans) having only male reproductive organs and some having only female reproductive organs? —JAO • T • C19:33, 12 July 2009 (UTC)[reply]
You are correct, I misunderstood the question. I suspect it has to do with the expense of maintaining parallel or bipotential reproductive systems not being worth it. There are a few vertebrates, like the wrasse that have capability to change sex if environmental circumstances make it advantageous. alteripse (talk) 20:17, 12 July 2009 (UTC)[reply]
Men and women exist because the far more primitive organism(s) from which we evolved found pressures to reproduce sexually. It was advantageous for some earlier link in the chain of life forms that led to us to reproduce sexually. It doesn't make sense to ask why we didn't switch back to asexual reproduction. (I realize the OP didn't ask this question.) The possibilities of the configurations both physical and behavioral of life-forms is bewildering. Why don't we have antennae? Why don't we possess the ability for echolocation? Bus stop (talk) 20:44, 12 July 2009 (UTC)[reply]
The primary function of sexual reproduction is to generate new combinations of alleles of the genes of two organisms. In hermaphroditically generated offspring, all the genes come from the same animal, so you don't get novel combinations. Looie496 (talk) 21:56, 12 July 2009 (UTC)[reply]
Plz help me quickly(some science related questions)
1>Which Filter is used for passing ONLY HIGH frequency
a: LADDER
B. crystal
2>If water is heated from 0degree to 10 degree effect on volume
a: increase steadily
b: remain same
c: decrease steadily
3>if we dig EARTH FROM North to South pole and a stone is dropped in it then efffect on its velocity
a :increase continously
b: First increase and become Zero in center
c. It Will Start Oscillate
4>Radiation pattern of loop antenna
a: cardioid b. semicircular c. circle d. none
Pardon me if I am mistaken, but this looks like homework. The Reference Desk does not do your homework. You can try reading the relevant articles or consult your textbooks. If you still have doubts in understanding any particular concept, we would be happy to help. Cheers. Rkr1991 (talk) 12:01, 12 July 2009 (UTC)[reply]
I also thought "homework" but I wonder what sort of class would ask questions that diverse. Anyway, coincidentally if there was a hole from north pole to south, or any other line through the centre of the Earth, and all air was evacuated from the hole, it would take 42 minutes to traverse the passage (42, of course, being the meaning of life, the universe and everything). Anyway, velocity of a falling object is due to acceleration due to gravity. At the start of the drop the stone would have the whole world ahead of it - the whole world has quite a bit of gravity. By half way, it'd have half the world ahead and half behind - so would be pulled equally in both directions. As it approached the other end of the tunnel, it would have more and more of the world behind it, pulling it back. Repeat. --203.129.49.222 (talk) 12:10, 12 July 2009 (UTC)[reply]
oh and...
1. A high pass filter passes high frequencies. <- If it's homework, check your text book. Radio filters can be made with crystals, but also look a little like a ladder.
2. Hotter gasses or liquids have greater volume. Water is a liquid.
Actually for number 2, the volume would increase, then decrease. Water reaches its maximum density at 4°C, which is why water expands when frozen. Chaosandwalls (talk) 13:49, 12 July 2009 (UTC)[reply]
This does sound an awful lot like homework - but much nicer answer to Q3 (which is a very complicated question unless there are a LOT of caveats) is that the air pressure in the hole increases the deeper you go - and quite a long time before you reach the center of the earth, the pressure would be sufficiently high to liquify the air - hence your rock will fall for a very long time (because it'll reach terminal velocity quite quickly) then make a very, very distant "splash" sound and then slowly sink to the center of the earth. If there is a vacuum throughout your tunnel then 203's answer above is good enough. For 203's benefit, the reason the hole has to go from North pole to South pole is because coriolis forces on the rock would cause it to hit the sides of the tunnel on the way down if it were drilled in any other direction...so it's NOT true that just any old hole would do! SteveBaker (talk) 14:21, 12 July 2009 (UTC)[reply]
I believe 42 is the answer to a couple of other interesting questions as well, which I vaguely seem to remember. I think it is half the time period of an infinitely ling pendulum, and something to do with waves which I can't remember.. And Steve, don't forget that these are just ideal imaginary textbook problems, so we should approach it without thinking too broadly...Rkr1991 (talk) 15:18, 12 July 2009 (UTC)[reply]
Perhaps you are thinking of the angle of the bow waves formed by a ship - irrespective of shape or speed through the water - which is 42 degrees. SteveBaker (talk) 16:13, 12 July 2009 (UTC)[reply]
I appear to be coming down with some nasty virus, and it has me curious. Nearly every time I get sick, I always get a very unpleasant feeling of general weakness, tenderness and soreness all over my body. It makes me want to curl up in bed and not move. Every tactile sensation, particularly unexpected ones, has a note of unpleasantness that it doesn't normally have. What is the cause of this general "unwellness" symptom? Note: I don't want a diagnosis, that's what I'll go to the doctor for. I'm just curious about the actual mechanism behind the symptom. Maelin (Talk | Contribs) 11:46, 12 July 2009 (UTC)[reply]
I have the idea that it comes from interferons and other cytokines. Exactly how they do it I have no idea. I seem to recall that this is considered to be adaptive because it keeps you from running off after mammoths while you're sick. --Trovatore (talk) 11:55, 12 July 2009 (UTC)[reply]
Malaise is my favorite symptom ever; it sounds like some sort of jungle fever. If you call up your boss and tell him your doctor says you have malaise, I can bet that boss is going to let you stay home. :-D -RunningOnBrains(talk page)22:45, 12 July 2009 (UTC)[reply]
What mechanisms trigger vasodilation?
I've been researching a minor affliction I suffer from which I think is cholinergic pruritus (but note that this is not a request for medical advice!). Assuming it is that, is the following an accurate description?:
I get too hot (or embarassed etc.) > ... > ... > Histamine is released as a vasodilator > This also makes C fibers fire which causes the itch sensation (H1 antagonists such as Loratadine are very effective preventatives.)
So, firstly, is that right?
Secondly, what happens in the dotted sections? How does thermoregulation work? What detects elevated temperature, what releases histamine (mast cells?) and how are signals sent between the two?
Thirdly, what is it that makes me different from most people? Is it how much histamine is released, or how sensitive the nerves are to it, or something else?
[From Terry0051] May I suggest some preliminaries -- like first taking a step back and having another look. Look at as many alternative explanations as you can find. It might not be the complicated thing you suspect. Common things happen most commonly. Skin is a temperamental and individual tissue/organ. For an otherwise healthy young person, traditional homespun measures to get you comfortable can often be all that is needed. Try various simple and safe measures. Beware of pharmaceutical (over)use. If still uncomfortable, get yourself along to a physician. Good luck. Terry0051 (talk) 21:07, 12 July 2009 (UTC)[reply]
Abdominal muscles
I have a feeling this question may well be rejected as medical advice but if it is, it was still worth trying. I'm currently working on my abs in hope of getting a sixpack and, after looking around online, the bicycle crunch seems to be the exercise of choice. Now I've been doing this for a while and have noticed it's getting easier and am looking for a way to make it more challenging, in the hope of causing more muscle development. Is there any suggested way of altering it? I've tried making my elbows meet my leg closer to the hip, rather than meeting at the knee as suggested, and this has definitely been tougher. I'm open to any suggested or even suggestions of different exercises to try. Thanks 92.2.120.88 (talk) 15:19, 12 July 2009 (UTC)[reply]
According to the crunch article, “the difficulty of the crunch can be increased by lying on a declined bench and/or holding a weight on the chest or behind the head.” Red Act (talk) 16:11, 12 July 2009 (UTC)[reply]
I'd imagine it's unlikely that the average person which achieve a six-pack merely through abdominal crunches. As mentioned above, you need to have sufficiently little fat for it to show. I got lucky in that I'm pretty skinny anyway, so exercises tend to work and I got one pretty easy (and as an unexpected byproduct of exercise). I recommend you just keep trying like you are, and if it doesn't work, combine it with another form of exercise which is more efficient at burning away fat (for example, running). As for altering it, or making it harder, the best way is to have weight added as suggested above. Remember though that the key point is reducing the fat levels around your stomach area sufficiently for a six-pack to show as it's pretty easy for fat to cover up the strongest of muscles. Regards, --—Cyclonenim | Chat 19:34, 12 July 2009 (UTC)[reply]
Video... thing to I.D
Not for the squeamish. Link. Online guesses include slime mould and tubifex worms. Neither seems quite right. To me, there's something wrong with the supposed scale in the vid; given the size of the supposed tunnel, you'd have to guess the large one here is about a foot high or thereabouts, but the water doesn't look right to me. Water doesn't miniaturize properly and the way this water behaves makes me think there's some trickery involved, like the tunnel is more like six inches high instead of six feet. Gross, anyway. Matt Deres (talk) 16:28, 12 July 2009 (UTC)[reply]
I'm not disagreeing - but the thing is red - can a slime mold be red? also the things move quickly and appear to be 1" long - I wonder if there's a mixture of different things in there? 83.100.250.79 (talk) 21:09, 12 July 2009 (UTC)[reply]
Watching Top Gear, they mentioned a new Zonda car which is made of something like Cartanium or some other made up name, a combination of carbon fiber and titanium. The first mention of titanium and carbon makes me think of titanium carbide, which if my memory serves me correctly, is brittle and thus a big reason we don't extract titanium through the blast furnace. Anyone heard about this cartanium or similar name, and why it's so different to titanium carbide? Regards, --—Cyclonenim | Chat 19:26, 12 July 2009 (UTC)[reply]
titanium carbide could like any other brittle material be made in to fibes eg glass fibres, basalt fibres
I've no idea what exactly they do, though I wouldn't be suprised if it were something like this [57], though it could equally as likely be something else involving titanium and carbon... (I'd imagine that the price of a relatively new material would be just as effective as preventing copying as secrecy - I doubt they were trying to cut costs on the design :) 83.100.250.79 (talk) 20:52, 12 July 2009 (UTC)[reply]
It would be easier to guess if it was known what part of the car was being made - other options exist - such as titanium metal with carbon, or titanium carbide fibre reinforcement, and carbon fibre with titanium carbide inside it eg [59] mentions brake discs. 83.100.250.79 (talk) 21:03, 12 July 2009 (UTC)[reply]
Primate Relatedness
I know that the apes are the closest relatives to humans, with the Chimpanzee/Bonobo being the closest to humans out of the apes. I also know that Old World Monkeys are then the next closest in relatedness to humans after the apes, but which living species of Old World Monkey is closest in relatedness to apes, and thus humans? Hot floppy bread (talk) 21:00, 12 July 2009 (UTC)[reply]
Remember that the evolutionary tree spreads (sideways), and is not purely linear - so that the old world monkey closest to apes is not necessarily the closest to humans. (Though it probably will be having said all that)83.100.250.79 (talk) 21:07, 12 July 2009 (UTC)[reply]
Indeed that is something I should have taken into consideration. If there are two different species for ape/humans I suppose I'd be interested in what both of them are. I was thinking it may possibly be a species of Macaque seeing as some of them have not much of a tail, although I suppose that it is far more likely a result of paralell evolution between the macaques and apes rather than a direct linear evolution from macaque to ape.
It seems that the prevailing opinion is that the old world monkeys are a monophyletic group, that is, they all derive from a single common ancestor species. This would mean that they are all equidistant from humans in evolutionary terms. Looie496 (talk) 21:39, 12 July 2009 (UTC)[reply]
Interesting, thanks. So that obviously explains the relatedness in evolutionary terms, but presumably the genetic relatedness to humans would differ within the old world monkeys, considering the wealth of diversity found within the family? If this is the case, which species would genetically be the closest (if this is even known at all)? Hot floppy bread (talk) 21:53, 12 July 2009 (UTC)[reply]
Even if the genes of all were known I think you would be looking at different species sharing and lacking matching dna (with humans) to varying extents (not necessarily the same sets of genes) - possibly with no clear winner. eg which of "1235" and "1245" is closest to "12345". Maybe it would be best to ask in terms of characteristics. 83.100.250.79 (talk) 22:05, 12 July 2009 (UTC)[reply]
Looking at characteristics leads to endless disputes with no principle way of resolving them. If you look at genes, and if you buy into the prevailing dogma that average rates of genetic change are constant over time, then the Law of large numbers applies: with thousands of genes to take into account, the differences between various species of monkeys and humans should all be the same to within a few percent. Looie496 (talk) 00:22, 13 July 2009 (UTC)[reply]
Gametogenesis in Hermaphrodites (earthworms)
I understand earthworms, nematodes, and several other species reproduce sexually with both sperm and egg production. Since they are hermaphrodites, and they perform both oogenesis and spermatogenesis, I wonder how they split their chromosomes during meiosis. Do they have an X and a Y, or do they have some type of sex determining chromosome?
And how exactly do they form sperm and egg? I know during meiosis in humans, it is supposed to be only sperm or only egg, and the determining chromosome, the Y in males, is what leads to the formation of male sex organs. Do earthworms have specific karyotypes for male or female? XX or XY?
And how are male earthworms made? (A small percentage apparently have only male sex organs).
I ask this because I have learned about the XX and XY chromosomes, but I can't understand the concept of meiosis in hermaphrodites.
THIS IS NOT MEDICAL ADVICE...I MAY HAVE MENTIONED NO EAR, NOSE, THROAT DR. WILL SEE ME OR TAKE IT SERIOUSLY. I NEED EXPERTS IN THIS FIELD OF SCIENCE! PLEASE RECONSIDER. —Preceding unsigned comment added by 98.154.194.138 (talk) 04:44, 13 July 2009 (UTC)[reply]
Please do not type in all caps. Based on the content of the message you left, now since redacted you need to see a live person to answer your question. The reference desk is not equipped to answer it. I would highly recommend a member of the medical profession. --Jayron32.talk.say no to drama04:54, 13 July 2009 (UTC)[reply]
Given the question, I think you might find that a psychiatrist might be more willing to see you than an ear, nose and throat doctor. In the yellow pages of my phone book, at least, there’s a category called “Mental Health Services”. Calling any one of the numbers in that section might be a good start toward finding a doctor (psychiatrist) who will see you. Even if you don’t believe that a psychiatrist is the kind of specialist you need to see, a psychiatrist is a fully qualified MD, and so would be a perfectly reasonable place to start for any medical condition requiring a doctor’s attention. Red Act (talk) 05:16, 13 July 2009 (UTC)[reply]
Tornado Hypothesis
Hi all,
I would like to open a discussion about a thunderstorm and tornado hypothesis I have developed. Where in Wiki would be the best place to present the theory and data I have compiled as it is to long to be placed here?
Thanks
Please do your own homework.
Resolved
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