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September 9

Laser beam expansion rates?

I've seen a few articles recently about laserstrikes on commercial aircraft coming in to land at various airports around the world, including a few discussing arrests of the perpetrators. The articles always mention how the laser fully illuminates the cockpit, and in one case the pilot was temporarily blinded and the co-pilot had to land the plane. That makes me wonder how wide the laser beam is at these altitudes. Considering it's only 1 or 2 mm wide at the point of emission, how wide would your average Class 2 laser be at 2000 feet? Or are these people using Class 3+ lasers to do their dirty work? Masked Booby (talk) 01:50, 9 September 2010 (UTC)

Do you have links to these articles? --Jayron32 01:56, 9 September 2010 (UTC)

This one was on BBC News some time back: Police fight back on laser threat. Nimur (talk) 01:58, 9 September 2010 (UTC)

There are many, if you had bothered to look, Jayron. Google News results Masked Booby (talk) 02:31, 9 September 2010 (UTC)

My 50 mW green laser pointer (very typical for the kind used in these laser attacks) has a beam that's 5 mm wide at 383 cm, so that's a beam angle of 0.0013 radians. At 1000 m, for example, it would be 1.3 m wide; at 2000 m, 2.6 m wide. --99.237.234.104 (talk) 03:10, 9 September 2010 (UTC)

Yes, but there will also be a loss of luminosity commensurate with the spreading of the beam. A beam that puts a dot of radius 1.3 meters will be (1.3/.005)² times less luminous, at those levels it may not even be noticed... --Jayron32 03:17, 9 September 2010 (UTC)

Slight correction: the laser beam is 2 mm at the origin, which makes the beam angle only 0.00078 radians. The beam would only be 0.8 m wide at 1000 m.

Pilots definitely do notice green lasers being shone at them at distances on the order of 1000 m. Pilots coming in for landing routinely suffer flash blindness from them, sometimes forcing the co-pilot to take over and land the plane. --99.237.234.104 (talk) 03:25, 9 September 2010 (UTC)

. Please cite sources; this is a Reference Desk. Comet Tuttle (talk) 17:09, 9 September 2010 (UTC)

Um, what I said about the pilots comes directly from the links that the OP gave. As for my own experiment, I admit that's OR. --99.237.234.104 (talk) 07:08, 10 September 2010 (UTC)

This makes me wonder whether laser pointers used for astronomy could be inadvertantly shining into an airplane, and what if the laser source is from a car? ~AH1^(TCU) 02:12, 12 September 2010 (UTC)

Hostage survival rates in modern times?

Here's an unusual question for you - has anyone ever studied/compiled statistics on the survival rates of hostages in modern times? By modern times I mean since the widespread prevalence of involuntary hostage-taking as opposed to the centuries old practice of exchanging people as collateral of sorts. Masked Booby (talk) 02:36, 9 September 2010 (UTC)

The FBI have apparently tried to do something with their HOBAS system but it only covers the US and Canada. See here for example. It gets a mention in FBI_Crisis_Negotiation_Unit#Initiatives. Sean.hoyland - talk 05:07, 9 September 2010 (UTC)

Stamp protection

The last time I bought pre-stamped envelopes from the post office (United States, btw), the stamps were actually pre-printed to the envelope. I took a good look at them, and there doesn't appear to be anything special about the stamps. They seem to be made of normal ink, and I can't see anything distinctive between them. Is there any kind of hidden protection on the envelopes or in the printed stamp to prevent someone from getting a high quality scan of the stamp and printing their own? Someguy1221 (talk) 09:50, 9 September 2010 (UTC)

In the UK stamps have, I understand, invisible phosphorous markings which allow their amounts to be automatically read. Your envelopes may have something similar. You would probably have to fake the envelope as well, which would cost more than the cost of the stamps. One of the stamps articles says that stamps often have hidden information coded into them, so there may be a secret code that signifies that design of envelope it should be with. On pragmatic grounds as well as ethical, do not do it as you will probably be found out. 92.15.3.53 (talk) 10:53, 9 September 2010 (UTC)

An interesting side note; a few years ago as an experiment I made a postage frank in mspaint (I don't have a scanner), printed it onto an envelope with a inkjet printer, and mailed it to myself. It arrived 82.44.55.25 (talk) 11:11, 9 September 2010 (UTC)

And technically, one could use a 50 year old stamp or older (with sufficient postage) and it would not have the same hidden markings, but would still be a valid stamp. Googlemeister (talk) 13:02, 9 September 2010 (UTC)

I wasn't aware of the word "franking" in that context. It's perhaps appropriate that the Canadian satirical magazine Frank got into a bit of trouble for publishing fake stamps with bizarre and/or humorous saying and pictures on them. Despite Canada Post claiming that they used state of the art scanning technology to prevent fraud of this kind, the writers found that virtually all their illicit mail was delivered, regardless of how obviously fake the stamps were. I get the impression that the amount of fraud taking place is so low that it would be more trouble than it's worth to crack down on it. Matt Deres (talk) 13:37, 9 September 2010 (UTC)

All US stamps have been tagged (read this article by someone from the American Philatelic Society) since the 1970s. As Googlemeister notes, it's possible to use older stamps; as a stamp collector buying from other collectors, I've often gotten envelopes franked with lots of older stamps from when first-class postage was a lot less than it is today. Nyttend (talk) 00:58, 10 September 2010 (UTC)

Over-efficiency as a cause of extinction

If evolution favors those species which are relatively best at adapting to their environment, can over-efficiency then be considered a cause of extinction? For example, if a predator evolves over time to succeed 100% of the time, and its prey does not recover, and the predator adapts no alternative prey, then the said predator goes extinct (for the purpose of this question at least). Now if a predator is successful only 5% of the time but thrives, then could it be said that efficiency is not a favored trait (unless it is relative to the evolution of its prey's efficiency of escaping), so a species that is "over"-efficient, or "uber-adaptable", may go extinct. I somewhere heard this could be applied to saber-toothed cats. Is this a valid concept and where can I find a good article on this? (using a dynamic IP; may change) 64.85.214.138 (talk) 10:07, 9 September 2010 (UTC)

Sounds akin to Malthusianism and the Malthusian catastrophe - albeit I get the impression he was more concerned about humans outgrowing the carrying capacity of the earth. --Tagishsimon (talk) 10:19, 9 September 2010 (UTC)

I was speaking more towards an already extinct species, one that did not employ agriculture or domestication of other animals. I don't mean this as an overpopulation/humans-are-bad question. Sorry for not clarifying. 64.85.214.138 (talk) 10:35, 9 September 2010 (UTC)

The model still applies. Malthus may have been concerned with humans, but (AFAIK) was one of the first to suggest that populations of any sort are limited by resources available to them. I'm sure your extinction concept is valid, though I cannot point you at examples. --Tagishsimon (talk) 10:38, 9 September 2010 (UTC)

The Lotka–Volterra equations describes what typically happens in predator-prey cycles. Occasionally there is a boom of prey, this is followed by a boom of predator. This causes a crash of prey, followed (inevitably) by a crash of predators. It only rarely drives one of the species to extinction. However, some prey have evolved solutions that have made their predators extinct; see the 13 year cicada for an example, although that idea might not be correct. CS Miller (talk) 12:03, 9 September 2010 (UTC)

I have heard of this, with snowshoe hares I think, but this type of boom-bust cycle has had time to evolve so that it settles at some kind of equilibrium, and then swings in favor of the other species, then temporary equilibrium, then swings in favor of the other other species, etc. In your cicada example, you refer to when prey out-evolve their predator, what I am referring to is when a predator out-evolves its prey -- when no equilibrium has time to evolve. It is just boom- but no -bust; it's boom-you're prey is extinct and then boom-you yourself are extinct. When prey win, adaptability pays off; when predators win, they have no food (unless they can create or grow their own -- I'm focusing only on predators that hunt or scavenge). (using a dynamic IP; may change) 64.85.220.14 (talk) 12:40, 9 September 2010 (UTC)

The Lotka-Volterra equations may be a bit of a red herring for the purposes of this questions. The solutions to those equations are not stable limit cycles, but neutrally stable. This means there is nothing internal to the model that prevents the kinds of extinctions that the OP suggests. As I see it, the problem that the OP describes is not extinction through `over efficiency', but extinction due to over-specialization. Basically, if a species' ability to grow/reproduce is tied too tightly to a single other species, then the extinction of one can cause the extinction of the other. This has probably happened many times through history. This does cause evolutionary pressure. For instance, many plant and animal pathogens have evolved NON-lethality, essentially to circumvent the problem the OP describes. I suspect very few predators are limited to EXACTLY one prey species, and many exhibit prey-switching behaviour based upon prey density. SemanticMantis (talk) 19:11, 9 September 2010 (UTC)

Oh, and the LV equations WILL produce the single boom, both bust when parameterized as the OP describes above. SemanticMantis (talk) 19:13, 9 September 2010 (UTC)

Headache + lack of exercise

This question has been removed. Per the reference desk guidelines, the reference desk is not an appropriate place to request medical, legal or other professional advice, including any kind of medical diagnosis or prognosis, or treatment recommendations. For such advice, please see a qualified professional. If you don't believe this is such a request, please explain what you meant to ask, either here or on the talk page discussion (if a link has been provided). --TenOfAllTrades(talk) 14:17, 9 September 2010 (UTC)

k1

are there any k1 kickboxing deaths?—Preceding unsigned comment added by Tomjohnson357 (talk • contribs) 13:28, 9 September 2010 (UTC)

Try the Entertainment desk. Brammers (talk/c) 06:18, 10 September 2010 (UTC)

power

How does the teethbrush charger transfer power to the teethbrush, when both parts are plantic because they get wet? Plastic doesn't conduct electrity —Preceding unsigned comment added by Whovandr. (talk • contribs) 13:38, 9 September 2010 (UTC)

Electromagnetic induction --Tagishsimon (talk) 13:39, 9 September 2010 (UTC)

Inductive charging, specifically. -- Finlay McWalter ☻ Talk 13:40, 9 September 2010 (UTC)

Why can't we remove scars?

When I was seven I got a tiny burn to the side of my face.

It looks like tere is a layer of skin missing from the shape of the burn and its pretty much invisible.

If skin cells are constantly regenerating why do we have scars?

There is no scar tissue from the wound its just looks like a tiny portion/layer of skin is missing.

I know its not possible to remove a scar with any of the current methods available. but would it ever be possible to remove a scar/ what would have to be done scientifically to remove a scar? —Preceding unsigned comment added by 139.62.222.73 (talk) 13:53, 9 September 2010 (UTC)

With MatriStem Wound Powder, a lady grew back part of her pinky finger. source: http://www.cnn.com/2010/HEALTH/09/09/pinky.regeneration.surgery/ 20.137.18.50 (talk) 14:30, 9 September 2010 (UTC)

yea, I heard about that but that is a little off topic.

Anybody else got info? —Preceding unsigned comment added by 139.62.86.190 (talk) 09:11, 10 September 2010 (UTC)

We sort of answered this question already here. The problem with scars is that the collagen gets deposited in a linear fashion to bridge the defect and hold it together, instead of in a random "basketweave" fashion which is what happens during normal skin development. In order to "remove" the scar, we would have to have a way to re-organize the dermal collagen. From a technical standpoint, this would require either a cell-based therapy involving injection of cells programmed to degrade the scar and re-establish the connective tissue correctly (remotely possible with current tech), or perhaps more futuristic technology like nanorobots (i.e. Sci-Fi). --- Medical geneticist (talk) 16:44, 10 September 2010 (UTC)

That Matristem is interesting, though the news seems to be coming from too close to the company for me to trust it (after all, fingertips sometimes regenerate anyway). "ACell's MatriStem Wound Powder is a sterile, porcine-derived, naturally occurring lyophilized extracellular matrix that maintains and supports a healing environment for wound management" ... "Porcine basement membrane promotes rapid wound epithelialization".[1] In theory, speeding up reepithelialization should reduce scarring, even if a scar has just been removed from the wounded area. Wnt (talk) 20:23, 13 September 2010 (UTC)

Ceramic pastes with high R values

I have these little metal rings used for holding eggs in while you fry them to keep them from running all over the place. These metal rings have stainless steel loop handles that stick up which get so hot as to be untouchable with unprotected fingers. I want to coat the top part of those stainless steel loop handles with some kind of material that is very resistant to changing its temperature. What commercially available product would fit the bill here? Thanks. 20.137.18.50 (talk) 14:24, 9 September 2010 (UTC)

I am dubious that a suitable material exists that you could successfully apply non-industrially (I wouldn't recommend asbestos!), though I'm open to enlightenment. Have you considered the alternative of using an oven glove or a similar but makeshift device? 87.81.230.195 (talk) 17:03, 9 September 2010 (UTC)

Wood? 92.29.121.183 (talk) 19:00, 9 September 2010 (UTC)

First: are you cooking on a gas range with it turned up really high? I fry eggs in a hot pan but turn the gas back down low. Once the albumin has turned white round the edges it should be possible to take the ring off and finish cooking. The loops tend to remain coolish (although you may have different ones). Have you tried lifting them off with a Carving Fork? Or an inverted wire coat hanger? Back to your question about R values. Polytetrafluoroethylene has good heat resistance whilst reaming a good insulator. Likewise there is Silicone rubber. The boots of the Luna astronaut where soled with this stuff to avoid them getting toasted tootsies. A way of getting very small quantity would be to take a ring to an electrical wholesaler and ask to see some cable for connecting hot water immersion heaters or other high temperature cable. The cable outer sleeving may just be the right size to slip over the loop. What would Gordon Ramsay use? His teeth? --Aspro (talk) 19:03, 9 September 2010 (UTC)

Your best bet may not be insulation, but active cooling. Soldering a large number of copper fins to the handles, or making handle extensions from loosely-coiled thin steel wire, may let natural convection cool the handles (or extensions) to the point where you can safely touch them. --Carnildo (talk) 22:03, 10 September 2010 (UTC)

Scientists break the speed of light

Are there any comments about such rumors? I can see them coming up again.--Email4mobile (talk) 14:45, 9 September 2010 (UTC)

We have an article on faster-than-light phenomena, including quantum tunneling as cited in the first Google result I looked at. It appears that this specific phenomenon is the 50-year-old Hartman effect. — Lomn 15:08, 9 September 2010 (UTC)

How about the two German scientists' (Sorry may be the 2nd older result about NEC reasearch)?--Email4mobile (talk) 15:20, 9 September 2010 (UTC)

The Hartman effect linked above specifically names the German scientists in question. Note that the article is now 3 years old. — Lomn 15:50, 9 September 2010 (UTC)

Potassium iodate used in bread

I always see this chemical used in bread. What does it exactly do? The articles are not specific. Would potassium chlorate be a cheaper alternative? --Chemicalinterest (talk) 15:31, 9 September 2010 (UTC)

It's used to ensure that people get enough iodine in their diet for correct thyroid function. Potassium iodate is commonly added to table salt for the same reason. A little bit of excess dietary iodine does you no harm, but a deficiency causes goitre. So no, you couldn't use potassium chlorate as an alternative! Incidentally, they use the iodate rather than the iodide because the iodide will slowly oxidize to elemental iodine, which wouldn't look too pretty in your bread or your salt. Physchim62 (talk) 15:35, 9 September 2010 (UTC)

A relevant paper abstract is here. Potassium bromate used to be used instead, as a bread improver. Brammers (talk/c) 15:37, 9 September 2010 (UTC)

No, the reasons for adding the two salts are different. Potassium bromate used to be used as a flour improver (apparently it strengthens the dough that is formed), although this rare nowadays. The potassium iodate that is added to flour in some countries is at a much lower concentration (about 2 ppm seems a common level), probably too low to have a useful effect on the strength of the dough. Physchim62 (talk) 15:59, 9 September 2010 (UTC)

I live in the US, if that helps. --Chemicalinterest (talk) 16:04, 9 September 2010 (UTC)

I do not see anything about iodine-enriched bread. The KIO₃ articles says it is used as a maturing agent. --Chemicalinterest (talk) 16:43, 9 September 2010 (UTC)

KI is added to my salt. Not the oxidizing anion iodate. --Chemicalinterest (talk) 16:43, 9 September 2010 (UTC)

Some countries use iodate for iodizing salt [2]. As for iodized flour (which will make iodized bread), our article on iodine deficiency mentions it with a reference. Physchim62 (talk) 16:58, 9 September 2010 (UTC)

In NZ, iodised salt is used to make iodine fortified bread [3] [4] [5]. I know folic acid fortified flour is used for bread in some countries including Australia (as also mentioned in our article), in NZ the plan was to add it during baking to enable organic breads to be excluded (I believe) [6] but the plan was deferred by the new government. Nil Einne (talk) 18:03, 9 September 2010 (UTC)

postman opened my door?

Question and responses removed. Questions that contain the phrase "Can I sue them" are requests for legal advice and should not be answered. Seek a lawyer if you intend to sue anyone. --Jayron32 04:21, 10 September 2010 (UTC)

Giants

As we know, there are many myths related to the existance of giants. However, in reality, actual "giants" are rare and those who have existed (eg. Robert Wadlow) are not as tall as those of the myths. So, my question is: what are the factors that limit people from growing 10, 12 or 20 feet tall? Many animals are bred for specific characteristics (eg. the Clydesdale horse); giraffes are tall and elephants are huge; in the past, there were many varieties of megafauna. So why not humans? 142.46.225.77 (talk) 15:58, 9 September 2010 (UTC)

It depends on how widely you're willing to apply the term 'human.' See Gigantopithecus, for example. Restricting ourselves to H. sapiens and close relatives, it seems that the right circumstances happened not to arise favouring development in that direction, but in principle they might in the (far) future. However, the necessary evolutionary changes would not be insignificant: consider that, like Robert Wadlow whom you mentioned, many human giants suffer from foot/leg/back problems because current human anatomy is not 'designed' to support their weight (square-cube law and all that). 87.81.230.195 (talk) 16:54, 9 September 2010 (UTC)

Our article Human height ought to answer this question, but does not; it just says, frustratingly, that growth subsides at a certain age. Once we've had a great answer here, could a knowledgeable editor improve Human height by adding the answer? Comet Tuttle (talk) 16:57, 9 September 2010 (UTC)

The ref to Gigantopithecus reminded me of a curious idea relating to human's body size (and brain size). Terrence Deacon, in his book The Symbolic Species, proposes a theory about why human brains differ from other primates. The way human brains, and bodies, develop (in the womb and in early childhood) "can perhaps best be described as though a human child is growing a brain from a much larger primate species. The human pattern of brain growth is appropriate for a gigantic ape, while the pattern of body growth is appropriate for a large chimp." How large an ape? Something around the size of Gigantopithecus. He explores the idea that humans did not evolve larger brains so much as smaller bodies. Or put another way, evolved larger brains by slowing the development of body growth but not brain growth. A key point is that humans don't simply have "larger brains" than other primates. Each part of the brain differs in how much larger or smaller than they "should be" for a human sized ape. The prefrontal cortex is the most "enlarged" (over 200%) and the olfactory bulbs the most "reduced". There's more to it than just this, of course, but it struck me as a curious notion. Perhaps a link to human neoteny? Pfly (talk) 19:36, 9 September 2010 (UTC)

Hmm, similar to some of Elaine Morgan's stuff in The Descent of the Child. She adds that the apparently anomalous lifespan of humans, compared to other apes our size, is in line with the size of our brains. So, that would be another way that we are more 'large with small bodies' than 'small with large brains'. 86.164.78.91 (talk) 13:16, 10 September 2010 (UTC)

There is little doubt that humans could be bred to be much larger than we are. But it would take hundreds of years of selective breeding. Who would go to the trouble? Looie496 (talk) 22:51, 9 September 2010 (UTC)

This guy's parents? Googlemeister (talk) 14:24, 10 September 2010 (UTC)

87.81.230.195 (talk · contribs) made some very good points "changes would not be insignificant" and "current human anatomy" re carrying that amount of weight. For a human to be that tall they would have to be so many changes that they might no longer be 'human', as we recognise them. Note that Wadlow at least looked rather thin and still had great problems related to his height /weight combination.("he required leg braces to walk, and had little feeling in his legs and feet.") He was 'only' 8 ft 11.1 in (2.72 m) and and weighed 485 lb (220 kg) at his death at 22.

• Lets compare a 6 footer to a 12 footer, keeping all dimensions in proportion so that they remain human. Height x 2, breadth x 2, depth x 2, I believe that their weight would therefore be 2³ = 8 x. However, all else being equal, muscular strength is relative to Muscle cross-sectional area (see point 2), so their muscles if remaining proportional, would only be 2x2=4. Weight x 8 but strength x 2 means that they would be half as strong as a 'normal' sized person.

• The bottom surface of the feet would also be x 4, with 8 x weight so twice as much weight per surface area.(look at elephant feet, very broad/flat and the legs, relatively short and very thickened bones. Highly modified from their distant ancestors and they are a quadruped).

• The spines cross section would also only x4 be while carrying 8x as much weight.

• Cooling might also be a problem, as the bodies volume has increased x8 but the Body surface area likely by a lesser amount. Not sure and I haven't calculated this. Elephants though tend to have large ears that are are also used as cooling devices.

♦ It seems our Giant human would live a (possibly) short life with constantly aching flat feet, if they could walk at all, scoliosis of the spine, and be very feeble. They could develop hugely thickened leg (and other) bones and huge feet. Or they would need to walk supporting the upper body on their knuckles (somewhat like Mountain gorillas) to spread the weight, becoming essentially a quadruped.

♦ There are probably other factors making giants unlikely that I have not covered, ie. blood pressure changes and food supply. If there are any flaws in my reasoning here, please point it out. 220.101 talk^\Contribs 05:31, 11 September 2010 (UTC)

Also, the 'myths' involving giants are treated more seriously in cryptozoology; there exist reports of giant sightings of purported creatures such as Old Yellow Top. ~AH1^(TCU) 01:53, 12 September 2010 (UTC)

Anatomy of a brain

Are human brains wired basically the same, the anatomy the same? Is it the chemicals and hormones that differ in each person, which control the strength of the signals among other things that make us unique? —Preceding unsigned comment added by 71.137.244.210 (talk) 16:09, 9 September 2010 (UTC)

To both of your questions, the answer is "yes and no." At the level of "gross anatomy" (what you can see by eye when you dissect a brain) the neuroanatomy is basically the same. Everyone generally has the same major structures, linked together by the same main bundles of axons. We also have generally the same wiring when you look at those structures under a microscope, for example the main cell layers of the cerebral cortex, the main cell layers cerebellar cortex, etc. However, it is safe to say that everyone has a unique microscopic arrangement at the level of the actual distribution of neurons in any given layer at any particular part of the brain, and a unique set of connections between neurons, etc. Secondly, in a general sense, we all have the same neurochemistry, meaning that our brains use the same neurotransmitters and neurotransmitter receptors to transmit signals between neurons. We share the same basic groups of neurons in various parts of the brain that use particular types of neurotransmitters. However, at a cellular level there will be all kinds of differences and fluctuations in terms of the strength of individual synapses. --- Medical geneticist (talk) 17:42, 9 September 2010 (UTC)

Right. There are hormonal factors that have important effects on personality, and probably anatomical differences that correlate with intelligence, but those things don't really make us unique. What makes us unique is memory, in combination with other effects of experience. Looie496 (talk) 22:48, 9 September 2010 (UTC)

What do you mean or if you could provide examples would be anatomical differences that correlate with intelligence? —Preceding unsigned comment added by 71.147.4.67 (talk) 03:19, 10 September 2010 (UTC)

See Neuroscience and intelligence. Lots of that stuff is pretty iffy in my opinion, though. Looie496 (talk) 06:13, 10 September 2010 (UTC)

Don't forget to read neuroplasticity, nature versus nurture and mental health. ~AH1^(TCU) 01:50, 12 September 2010 (UTC)

Integrated theory

The reason I've asked about breaking light speed rumors is that some are trying to reformulate physics and its laws reasoning that under the name of Integrated theory like this web under construction.

I will quote his introduction here:

"There is a need for a single unified theory, could explain all the phenomena of nature. and reduce all theories of physics in one, able to explain and interpret what interpreted by earlier theories and give more than all. predict conclusions of the future, of the realities of the universe. And interpretation of what all theories can not be interpreted or understood. Then put a convincing philosophical theory, based on scientific facts that are not in doubt, the aim to unification of the human thinking so not to be dispute. Uniting all forces of nature on the grounds that is properties of the material. And give causal explanation of all events and phenomena. And be simple and streamlined, universe simpler. And re-explanation of what other theories failed to interpret. This theory is different and collide with the old concepts, but not with the truth, a single, unified, comprehensive and integrated basis on truth. Most importantly, uniformity of laws, which apply to the solar system with atom Laws. it is causal theory of distinction. most of our concepts of physics, was based on erroneous grounds. such as Characteristics of the wave for the particles, and zero mass, and the idle talk about the fourth dimension, and the madness of Mathematics at super string theory, and leaps electrons Bohr, and the shortsightedness of the Big Bang theory. Theory relies new foundations and the most important is the new atomic model, adds particles to atom, smaller than electrons. and focuses on the structure of elementary particles. We got to know that this theory interpret black holes, dark matter, and sunspots. In short, tell us the truth about the universe. Relates to the impact of global warming of Earth's surface. Focus on the gravity, and develop a new understanding of energy. And provide a deeper understanding of the so-called forces of nature, and give a causal definition of the charge, and then address the speed of light, it have the ability to give causal answers to, all phenomena of nature. At first it seems weird and difficult to understand, because they contradict with the foundations of earlier theories, but after you complete the understanding it will be simple and very easy, and not to forget, and internally consistent, and enable us to conclude everything easily.", Dr: Sadi Said Mona

Do you think this man is serious?--Email4mobile (talk) 17:03, 9 September 2010 (UTC)

Serious? Sure. Correct? Unlikely. See Fringe science and Pseudoscience. People claiming to have re-invented large segments of the study of physics are pretty common on the Internet, and Wikipedia's WP:V verifiability policy came into being largely to stop physics cranks from posting their fringe theories as articles here. Comet Tuttle (talk) 17:13, 9 September 2010 (UTC)

It's important not to conflate fringe with crank. The high-risk-high-reward area of any discipline is always on the fringe. Unfortunately the well-intentioned practice of saying fringe when you really mean crank has tainted the former word, and we now probably need a new one. --Trovatore (talk) 21:15, 9 September 2010 (UTC)

You're right; I'll be more careful in the future. Comet Tuttle (talk) 19:11, 10 September 2010 (UTC)

Looks like the site is trying to introduce a new deterministic holistic hypothesis competing with the Grand Unified Theory and others. ~AH1^(TCU) 01:46, 12 September 2010 (UTC)

He's trying, AstroHurricane but in order to defect them. He is trying to prove that photon is not mass-less by citing some information about new limits on its mass. Furthermore, he wants to convince that mass–energy equivalence formula is not true and must drop in to the half (i.e. classical K.E). He also got some citation about breaking light speed; the reason I wanted to understand if it were really true or just virtual. He is promising to show totally new laws of physics that are more robust, not complicated, and also less number of dimensions. Anyhow I will be following that site from time to time to understand how he is going to change our thinking (He sounds to be a doctor, not a physicist and also not well familiar with English).--Email4mobile (talk) 12:06, 13 September 2010 (UTC)

Feynman Famous?

Hello again, this is sort of a follow-up to a previous question I asked a few weeks ago about how to pronounce his name. After reading "Surely You're joking", I started on a collection of his letters, and was struck by a passage that said how Feynman was very famous with the general public, almost as much as Stephen Hawking or Albert Einstein. However, when I told a few people that I was reading the letters of Feynman, only two people from the twenty I asked knew who he was (one was my Physics teacher, who I don't think counts as the general public); yet I have no doubt they would all have know who Einstein or Hawking were.

Is Feynman simply much more famous in the US? (I live in the UK)--HarmoniousMembrane (talk) 17:25, 9 September 2010 (UTC)

I would say that Feynman (and also Hawking) have largely been known in the public for their efforts to popularize science. People who are effectively spokesmen for science tend to be known during their lifetimes, but the public forgets about them relatively quickly after they die. By contrast, Einstein is known to the public for his actual science (other examples might be Newton or Galileo). When the science itself becomes part of the public awareness, then the person behind it tends to have a much longer legacy. Of course Feynman also did top notch science, but that was never really why he was known to the general public. Dragons flight (talk) 18:05, 9 September 2010 (UTC)

If Feynman had had crazy hair and his work could be put in a nutshell as compactly as $E=mc^{2}$ his image and therefore identity might have also been conveyed to Joe Six-pack via cartoons and other cultural pellets consumed by the general public. 20.137.18.50 (talk) 18:10, 9 September 2010 (UTC)

Good point! Path integrals just don't have the same simplistic elegance. P. D. Cook ^{Talk to me!} 18:22, 9 September 2010 (UTC)

From the Rogers Commission Report article regarding Feynman's role in investigating the Space Shuttle Challenger disaster: "During a televised hearing, Feynman famously demonstrated how the O-rings became less resilient and subject to seal failures at ice-cold temperatures by immersing a sample of the material in a glass of ice water." That may have been the point at which he got the most attention from the general public. Wikiscient (talk) 19:02, 9 September 2010 (UTC)

Surely it's more impact than compact that gives $E=mc^{2}$ and its discoverer lasting fame. --Sean 22:52, 9 September 2010 (UTC)

It's definitely true that the association with nuclear weapons boosted that particular equation's notice in the public eye (graphically depicted in this Time magazine cover from 1946), but Einstein was actually already pretty famous before the atomic bomb, on account of the widely publicized and popularized success of theories after the Solar eclipse of May 29, 1919, and because of his very public activism during World War I and against the Nazis. He was already a public figure long before the bomb, but the bomb really capped it off. --Mr.98 (talk) 23:46, 9 September 2010 (UTC)

Nazis were World War II. SpinningSpark 01:14, 10 September 2010 (UTC)

The Nazis took over and did all sorts of nefarious things related to Einstein well before WWII. (Much less if we taken into account their pre-power hijinks as well.) See Deutsche Physik, among other things. Einstein was known for his anti-Nazi stance years before the war had started. --Mr.98 (talk) 01:23, 10 September 2010 (UTC)

And Einstein was active in the pacifism movement during WW1, even though Wikipedia's article about him doesn't seem to mention it. See Martin Gilbert's book on the war, for example. So "during WW1 and against the Nazis" was quite correct. --Anonymous, 03:51 UTC, September 10, 2010.

Oh, yes, I didn't realize that was the part under dispute. Einstein was very active during World War I as well, I guess I should clarify. He was one of the most prominent German scientists who was outspoken against German militarism (most of the others climbed on the Kaiser's bandwagon without hesitation). Wikipedia's Einstein article is presently a huge mess and seems to have been taken over by at least one POV-pusher, so I wouldn't put much faith in it myself, unfortunately! --Mr.98 (talk) 12:43, 10 September 2010 (UTC)

Einstein was a popular figure starting in 1919, amplified in the 1930s, sanctified in the 1940s, and at his death became the symbol of "science" around the world. Hawking on the other hand was mostly popularized through A Brief History of Time in the late 1980s, if I recall correctly. Hawking is culturally poignant not because of his scientific work, but because of his "brain in a ruined body" symbolism. I don't think he's quite on the same level as Einstein as a cultural icon, but the symbolism is pretty strong. I suspect that in the long run, he will be more of a Feynman-level of popular understanding — someone that smart, science-nerds know about, but not the general public (unlike Einstein). Incidentally, though, my wife had a shirt on the other day with Einstein's photo on it, and someone (who happens to be quite uneducated) asked her, earnestly, if it was George Washington. So I suppose we should not overestimate even his penetration into the mind of the common man! --Mr.98 (talk) 01:28, 10 September 2010 (UTC)

FWIW, I think Feynman wrote in that book that in WWII Americans knew Einstein as a mathematician; few people knew what physics is. Imagine Reason (talk) 21:50, 10 September 2010 (UTC)

Thanks for all the answers, guys. I can definately see what you're getting at, but I thought someone might find it useful that quite a few scientists still think he was a great man, as shown in the Guardian today: Attenborough and Dawkins Brian Cox and Hawking--HarmoniousMembrane (talk) 16:34, 11 September 2010 (UTC)

Sure, he's well known amongst scientists and people who read about science. No debate there. But I doubt he's well known outside that rather limited sphere. Whereas probably everyone knows Einstein's face and most people would know the robot Stephen Hawking voice. --Mr.98 (talk) 00:09, 12 September 2010 (UTC)

Lumen Loss

All other things being equal, what would be the approximate lumen loss of a 130v 150w halogen lamp operating from a 120v source compared to a 120v 150w halogen lamp operating from that same 120v source (nominally 2400 lumens). This (marketing?) technique is sometimes used to advertise a longer lifetime or enhanced ruggedness but of course at the expense of lumens. hydnjo (talk) 20:09, 9 September 2010 (UTC)

Wrong question: Marketing? The nominal voltage may be 120 but 50% of the consumers live close enough to the sub-transformer to be supplied with 120 plus volts. This would shorten the life of a 120 volt rated bulb filament dramatically. Hence the 130 rating. Make sense?! --Aspro (talk) 20:53, 9 September 2010 (UTC)

Also, The human eye is more sensitive to sorter wave lengths (ie. 550 nm). An over-run bulb will run hotter (but not more efficiently). It will appear brighter (more energy being converted into light) and in wave lengths the eye is more sensitive to ) but to quote Tyrell: 'The light that burns twice as bright burns half as long, and you have burned so very very brightly, Roy. Look at you. You're the prodigal son. You're quite a prize! [7] --Aspro (talk) 21:05, 9 September 2010 (UTC)

The two products are sold side by side from the same manufacturer. One (the 120v 150w rated} has no claim as to extended lifetime or increased ruggedness. Right next to it is the 130v 150w rated one with the claims mentioned. I'm pretty sure that the two lamps are intended to be sourced from the same 120v (nominal) supply, I'm trying to find out what the reduction in lumens would be if I opt for the 130v version (claimed lifetime of 4000 hours if operated at 120v) vs the 120v version (claimed lifetime of 2000 hours if operated at 120v). Does that clarify? hydnjo (talk) 21:14, 9 September 2010 (UTC)

There is about a 9% difference between 120 and 130 volts. If your board voltage is 130 v you should be asking yourself if you want to run up and down the steps changing blown bulbs or not. If your at, or below 120v, then it don't really mater and its academic. The human eye adapts and I don't think you will notice, so it's a pointless question asking about lumen. In photography I think it will be less than a third of a stop. For what earthy purpose prey, do you neeeed to be sooo precise? Get someone to meter your supply and tell you how many volts you're getting (important:switch some things on so you have some load -like a cooker). THAT voltage should indicate what bulbs you buy, rather than how many lumens you feeeel you need. If however you really mean lumens, then please repost on Reference desk/Trivia --Aspro (talk) 21:46, 9 September 2010 (UTC)

Just in case anyone gets confused over in the UK or Australia. There they have an asymmetrical nominal voltage declaration. Bulbs carry the 240 volt rating, which is correct for the average voltage delivered. This takes account of the higher voltages that occur nearer to the sub-station. The voltage supply is of much better quality and thus, two voltage options on bulbs are not required.--Aspro (talk) 21:50, 9 September 2010 (UTC)

This has gone way beyond my intended concern but here goes anyway. The security floodlights around my residence are doubly housed 150w halogen lit. My home is powered by a nominal 120v service. I need to replace one or two of the bulbs at this time. For reasons of aesthetics I don't wish to have one lamp significantly less bright than its 150 cm away neighboring lamp. I was hoping to get a response as to how much (qualitatively) brightness difference I might expect to perceive from opting for the 130v version as opposed to the nearby 120v version - that's all! This thread has gone way off track from my original question perhaps because of my in-artfull presentation but if you think you know what I'm asking please chime in. Thanks hydnjo (talk) 22:41, 9 September 2010 (UTC)

Power varies to the square of voltage. Assuming the load resistance does not change with the lower voltage (not an entirely accurate assumption - cooler running = lower resistance) and the efficiency is linear with power (also not entirely accurate) the radiant output will be (120/130)² = 85% of previous output. You will be 15%, or 360 lumens down. This book suggests that a more accurate formula is 3.38 rather than 2 as the exponent. Using that gives you a loss of 24% rather than 15% from the simplistic calculation. SpinningSpark 00:37, 10 September 2010 (UTC)

We have an article on this Lamp rerating. --Gr8xoz (talk) 00:50, 10 September 2010 (UTC)

• Thanks to both SpinningSpark and Gr8xoz, you both figured out exactly what I was asking and both of you provided excellent references. Looks like I should stick with the same 120v lamps that are all around the house as the luminosity difference with the 130v lamps would be quite noticeable and annoying and not worth the extra life expectancy. And Gr8xoz you've shown once again that WHAAOE! hydnjo (talk) 01:32, 10 September 2010 (UTC)

This analysis has been done in detail constantly by lighting engineers since about 1881, with tradeoffs between efficacy and lifetime carefully measured and analyzed. Edison (talk) 05:27, 10 September 2010 (UTC)

I'm sure that's true, but without providing any links or information that answer the question (as SpinningSpark and Gr8xoz did), you haven't really added anything to the answer. Did you mean to include a link? 86.164.78.91 (talk) 13:04, 10 September 2010 (UTC)

It is not a requirement to provide a link or reference with every posting. Sometimes a lifetime of study of a subject provides insights which may be helpful. One may have read something in a reference work which is miles away in a library and not easily citeable. An additional point is that empirical formulas derived for, say ordinary tungsten filaments in vacuum may not be accurate for a bulb filled with inert gases, or those for a bulb filled with inert gas may not be accurate for halogen, and formulas accurate for 240 volt filaments may not be accurate for 120 volt or lower rated filaments. These are not laws of physics like an ideal gas law or Ohm's law. Edison (talk) 15:16, 10 September 2010 (UTC)

• OK - resolved without the template. Additional thanks to Edison for his pragmatism and to 86.164.78.91 for their support after some of the earlier comments. Edison is right, this has lots of scientific study and empirical evidence available. The reason for there being two such similar products next to each other is that a compromise product (the 130v version operated at 120v) has been found to be marketable with the portable "rough duty" customers who are less concerned about the amount of light loss (20% - 30%) than the ability to withstand rough handling. The 120v version is the optimal choice for the average user with a fixed (non-bumpy) location and provides the appropriate balance of luminosity and life expectancy. hydnjo (talk) 21:03, 10 September 2010 (UTC)

Asbestos: regulation and risk to neighbours in the UK

Hello.

It seems that most asbestos legislation in the UK deals with occupational safety - the safety of workers and the responsibility of employers. Most of the science I can find deals with the same thing. I am interested in the risk to the general public - and nearby neighbours in particular - that may or may not be caused by work such as demolition.

So, my question to Wikipedians who wish to help me is:

What are the known risks to occupants of neighbouring buildings, of the demolition of nearby buildings which are known to contain asbestos? What precautions - in relation to those residents - are prudent? What precautions are required?

I've tried to research this myself, but all I can find are general medical and scientific studies of the dangers of asbestos, and laws and regulations relating to occupational safety and procedures. I have tried hard, but I cant find any information to help me answer my question.

Please note: I am definately not asking for legal or medical advice - I am purely looking for background information, as this seems like a hole in the regulatory system here in the UK.

I would be very grateful for any links that may be of interest.

Many thanks to anyone who wishes to answer.

Contactless (talk) —Preceding undated comment added 21:52, 9 September 2010 (UTC).

The general law in the area is section 3 of the Health and Safety at Work etc. Act 1974:

General duties of employers and self-employed to persons other than their employees.
3.—(1) It shall be the duty of every employer to conduct his undertaking in such a way as to ensure, so far as is reasonably practicable, that persons not in his employment who may be affected thereby are not thereby exposed to risks to their health or safety.
(2) It shall be the duty of every self-employed person to conduct his undertaking in such a way as to ensure, so far as is reasonably practicable, that he and other persons (not being his employees) who may be affected thereby are not thereby exposed to risks to their health or safety.
(3) In such cases as may be prescribed, it shall be the duty of every employer and every self-employed person, in the prescribed circumstances and in the prescribed manner, to give to persons (not being his employees) who may be affected by the way in which he conducts his undertaking the prescribed information about such aspects of the way in which he conducts his undertaking as might affect their health or safety.

Of particular relevance to demolitions is regulation 29 of the Construction (Design and Management) Regulations 2007:

Demolition or dismantling
29.—(1) The demolition or dismantling of a structure, or part of a structure, shall be planned and carried out in such a manner as to prevent danger or, where it is not practicable to prevent it, to reduce danger to as low a level as is reasonably practicable.
(2) The arrangements for carrying out such demolition or dismantling shall be recorded in writing before the demolition or dismantling work begins.

With regard to asbestos, the prudent approach is to remove as much of the asbestos as possible before demolition; otherwise, the whole demolition job would need licensing under the Control of Asbestos Regulations 2006. I don't know of any specific studies done on the risks to neighbours during demolition work. Court cases are only just getting round to dealing with the health damage to neighbours of asbestos processing plants: these people are at far more risk because the (potential) exposure is longer. Physchim62 (talk) 22:54, 9 September 2010 (UTC)

It depends on whether the demolition of the building containing asbestos is conducted according to regulations or not, and the size of the building/amount of asbestos. If the demolition abides by the regulations, airborne asbestos levels will be very low and I don't think health precautions are necessary for neighbors in standard cases. As mentioned above, larger projects might be different. If you're particularly worried and it's a windy day, then you could stay inside and keep doors and windows shut, or use a mask. If you want to see more information on the aforementioned regulations, check out this link. Regards, --—Cyclonenim | Chat  23:00, 9 September 2010 (UTC)

Thanks to both of you for putting the effort in to reply. I should probably have said that I had found the legislation Physchim62 kindly found, and the HSE link that Cyclonenim gave. Thanks for those though guys! But it does seem strange that, other than the very general duty of care to others contained in these regulations, there is little mention of risk to others such as neighbours. Dont you think?

The HSE has lots of information about worker's safety - respirator types, fibres per cc of air, decontamination procedures, licensing rules etc. - but none that I can find about precautions for the general public. It is strange to see, on a construction site, workers in full plastic hazard gear, with gas masks and disposable boots - even mobile decontamination shower units - while only feet away are members of the public watering their pot-plants in t-shirts! It just seems like a slight disconnect to me.

Anyway, thanks a lot for your help.

Regards Contactless (talk) 00:32, 10 September 2010 (UTC)

This is not legal or technical advice, just an observation. I once underwent "official" training in US asbestos removal procedures. The jist of it is that asbestos had to be removed only in an environment (plastic sheeting, negative air pressure via HEPA filters) where it was not dispersed in the environment. The problem area was enclosed with layers of plastic to constitute a sealed area. It was wet down and then scraped off the beams, pipes, boilers, ceilings, or whatever by workers with respirators and protective suits, and bagged for disposal. When they were done, and showered, the suits went into disposal bags and the inner plastic walls, floor and ceilings went into disposal bags. Then the air was monitored to make sure there were no fibers drifting around, before all the plastic was removed. Those regulations would not have permitted open air removal with the fibers drifting around the neighborhood. Just knocking down the building and letting the fibers drift around would not seem in accord with the US standards I was familiar with. Edison (talk) 05:22, 10 September 2010 (UTC)

Exactly the same (or a very similar) system is used in the UK, and licensed contractors go to great lengths to ensure that no asbestos fibres escape to the outside environment. You should be aware, however, that asbestos and other potentially carcinogenic particles exist (in a very small quantity) in normal atmosphere in the UK (and probably elsewhere). The risk from these (and from most demolition work) is so low that most of us don't bother to wear special masks when going about our everyday tasks. If you are really worried, perhaps you should ask to see certificates of asbestos removal which should have been obtained before demolition work stated. There are always some "cowboys" who ignore regulations. Dbfirs 13:03, 10 September 2010 (UTC)

Thanks a lot for helping me out - those are good, reassuring answers. I'm definately not one to make a fuss about health - I just wanted to make sure that the protection rightly afforded to workers (who are obvioulsy at much greater risk) was not to the exclusion of the general public, especially as this is a very high density residential neighbourhood.

The contractor is definately licensed for the task and reputable. I think I'll just write a quick letter to the council (who approved and gave notice of the demolition) and just ask them to confirm that reasonable measures have been taken to minimise any danger to residents.

Thanks again for your help.

Regards Contactless (talk) 23:00, 10 September 2010 (UTC)

Particle board

is it possible to make particle board with epoxy or yellow PVA glue or urethane glue instead of formaldehyde resin —Preceding unsigned comment added by Tomjohnson357 (talk • contribs) 22:54, 9 September 2010 (UTC)

I suppose it is possible to create your own particle board at home using your own matrix and binder system; any suitible binder should work. However, I imagine that quality control would be an issue. The stuff that's made in big factories tends to have better uniformity of properties and conforms to higher standards than something you whip together in your workshop with sawdust and glue. --Jayron32 05:45, 10 September 2010 (UTC)

The article Fiberboard, which covers the class of building materials that includes particle board, mentions some of the issues with formaldehyde-based resin systems, and mentions some alternatives which are in production. --Jayron32 05:48, 10 September 2010 (UTC)

How do frogs get into an isolated marsh?

This is a question that has intrigued me. I will give an example.

As I like to do, I explored a dry drainage ditch to its source beside a shopping mall. There was a small pool of water and mud. As I walked past, several small frogs jumped in. The nearest frogs were in a pond about 1/2 mile away.

So: How did the frogs get there? --Chemicalinterest (talk) 23:14, 9 September 2010 (UTC)

Although virtually all frogs have to breed in water, they frequently don't have to live in it, and many species spend much of the year out of it (though often sheltering in shaded and moist nooks and crannies, especially during daylight), during which they can disperse considerable distances in search of 'greener pastures.' The frogs you saw might easily have travelled more than half a mile to this intermittent pond (though it's not unlikely that some live closer than that without your realising). Alternatively, they may be a small population living permanently around the site, breeding when water is seasonably available and sheltering in the aforesaid nooks etc when not.

It used also to be said that frogspawn is dispersed by its sticking to wading birds' legs and being transported by them from one body of water to another, but I'm not sure how much of this was merely assumption rather than observationally confirmed. 87.81.230.195 (talk) 23:46, 9 September 2010 (UTC)

The area is developed, so it is easy to spot marshes. --Chemicalinterest (talk) 00:16, 10 September 2010 (UTC)

Are you certain that they were true frogs, not just tree frogs? Nyttend (talk) 00:54, 10 September 2010 (UTC)

Yes, they are true frogs. Bronze frogs, most likely. They are one of the most common frogs in my area. --Chemicalinterest (talk) 10:55, 10 September 2010 (UTC)

Also, don't forget that there would be a very large and complex subterraneal storm water drainage system that I imagine frogs would love to travel around in. Vespine (talk) 02:29, 10 September 2010 (UTC)

Frogs like light more than darkness. The storm drain is at the end of the stream. The frogs are at the beginnning of the stream. The spring at the beginning of the stream has dried up, although the water is still high. That is why there is still a puddle there. Frogs normally like mud, too. It gives them a better place to hide. Cement is hard to hide in. --Chemicalinterest (talk) 10:55, 10 September 2010 (UTC)

Frogs can wind up in odd places. I once found a somewhat dehydrated and emaciated but quite lively frog in a small recess in a television mast on top of a house. I cannot picture the frog climbing up the wall of the house, and my best guess is that he was grabbed by a bird and subsequently dropped while the bird was above the house or perched on the mast. So a frog in an "isolated" pool is not at all surprising. Edison (talk) 05:12, 10 September 2010 (UTC)

That is strange. It reminds me of something similar. Many times when it rains, we find earthworms on our porch. The porch is about 2 1/2 feet above the soil. --Chemicalinterest (talk) 10:58, 10 September 2010 (UTC)

See Raining_animals#Frogs_and_toads for referenced, documented cases of frogs raining from the sky. It is rare, but it apparently does happen. Checking earlier in the article, apparently waterspouts and tornados can carry water-borne creatures some distance, resulting in rains of fish and frogs and other oddities. --Jayron32 05:16, 10 September 2010 (UTC)

Here's one possible answer. As our frog article says: Some frogs inhabit arid areas such as deserts, where water may not be easily accessible, and rely on specific adaptations to survive. The Australian genus Cyclorana and the American genus Pternohyla will bury themselves underground, create a water-impervious cocoon and hibernate during dry periods. Once it rains, they emerge, find a temporary pond and breed. Looie496 (talk) 06:11, 10 September 2010 (UTC)

I live in the eastern US, if that helps any. --Chemicalinterest (talk) 10:58, 10 September 2010 (UTC)

I saw a bird carrying a frog once, and then it dropped it. The frog was unharmed and hopped away to safety. Maybe that's how they got there Quadrupedaldiprotodont (talk) 14:19, 10 September 2010 (UTC)

Here in Ireland I have seen Common Frogs in a wooded area near my house from time to time even though the nearest lake is about half a mile away. I see them very rarely but they travel this far away from water nonetheless.--92.251.241.196 (talk) 18:19, 10 September 2010 (UTC)

For true frogs in genus Rana, half a mile is not a big distance. While adult frogs normally stay in the same pond, juveniles disperse to large distances in search of new ponds. This paper gives the dispersal distance of about 1000 m (0.62 mile) for the wood frog Rana sylvatica; but of course the dispersal distance depends on weather, terrain, and the species of frog. Half a mile is not a problem. In fact, many species of frog breed more successfully in vernal pools and other ephemeral bodies of water, as the absence of large fish guarantees reduced predation and reduced competition. It is probably also an evolutionary adaptation for the species to be able to spread to the new available habitats. --Dr Dima (talk) 18:21, 10 September 2010 (UTC)

They were young frogs, I could tell by the splash instead of the plunk. . --Chemicalinterest (talk) 20:09, 10 September 2010 (UTC)

I have seen young frogs jumping out of a muddy puddle in the middle of a trail in a forested region. The puddle was likely fed by a stream or even by intermittent rains. Could your frogs be breeding there whenever the puddle exists and has not dried up completely? ~AH1^(TCU) 01:25, 12 September 2010 (UTC)

Yes I have seen pickerel frogs in a puddle. The puddle can be known as a vernal pool. They are nice. But what I was asking: How did the frogs get to the puddle in the first place? It seems from the above replies that true frogs can hop long distances overland. --Chemicalinterest (talk) 10:58, 13 September 2010 (UTC)

I have heard that fertilized frogg eggs might get stuck to the feet of ducks and other water fowl and get transfered over long distances when the birds travel from one water reservoir to the other. 87.207.53.174 (talk) 04:01, 13 September 2010 (UTC)

You have an interesting point. There is a lake with tons of frogs. Then there is the source of the lake (a water basin) with lots of ducks. Then there is the little puddle, with some frogs. --Chemicalinterest (talk) 10:58, 13 September 2010 (UTC)

September 10

Remote controlled almost self-replicating small production systems.

Has there been any practical experiments with self-replicating machines using mostly “bulk” material?

Large-scale space-activity require production in space since the launch cost from earth is so high. Before large-scale production in space is implemented it is extremely expensive to have a human workforce in space. Production should therefore be remote controlled or automatic.

The current global industrial complex is able to replicate itself and to a large extent automated but it is way to complex and big to be a god model for something to send to the moon, asteroids or the moons of Mars. Most of the work on self-replicating machines seems to be either theoretical or using prefabricated parts. I would be interested in attempts to build machines that can replicate most of its mass from bulk material, parts that are hard to build such as semiconductor chips will of curse need to be prefabricated. I know that we don't have the technology to build self-replicating machines that uses raw material such as lunar-regolith but machines that uses simpler bulk material such as plastic granulate is an important step.

I find the RepRap-project interesting but limited since it is built mostly of prefabricated steel bars and need to be mounted manually. Are there similar research projects that are more ambitious and professional? Have they build functioning prototypes?

I have read Self-replicating machine and Clanking replicator Gr8xoz (talk) 00:23, 10 September 2010 (UTC)

Based on your interests, you might find this old Soviet SF short story interesting: Crabs on the Island, Masked Booby (talk) 01:30, 10 September 2010 (UTC)

I havent had time yet to reed it but it sounds intresting thank you for the link.Gr8xoz (talk) 11:43, 10 September 2010 (UTC)

I don't know whether you can say the RepRap isn't 'ambitious'. Their goal is indeed that most (well theoretically all, but I think most would acknowledge that's a very far off dream) of the machine be self-replicatible i.e. the number of 'vitamins' be kept to a minimum. And there is the Kartik M. Gada prize that's been offered related to the RepRap [8] which requires, amongst other things, 90% of the volume be printable. (See for example [9] one of the projects which is aiming to eventually meet the requirements of the prize.) Note that one of the goals of many developers for the RepRap includes work on making printed circuit boards and perhaps even assembling the boards via some sort of pick and place technique. However it's true they're centred on low cost and earth usage so some self assembly isn't usually seen as a big deal provided it's something most people can do without needing much training or experience, but I don't think you can say this isn't ambitious, they just have a different goal from what you're looking for. In particular, building or assembling something that is the same size as the device building it raises several issues potentially requiring the device is capable of moving by itself rather then occupying a fixed space and building something that requires no human involvement requires a very high degree of reliability or otherwise the internal ability to fix problems that arise (even the KMG prize allows one printer head jam to be fixed) and a resonably consistent degree of built quality. Of course being ambitious doesn't mean you don't recognise the limitations you currently face, hence why the RepRap team is concentrating on building something that works and then improving it until it can make most of itself. Nil Einne (talk) 07:11, 10 September 2010 (UTC)

I was more looking at the current prototype than the overall project goal. A useful self-replicating system in space need of curse be able to move it self or it's offspring any way to avoid crowding. I did not rule out human intervention but the intervention should be performed by remote control. A robotic arm on wheels produced by the RepRap system would be an interesting step towards self assembly.Gr8xoz (talk) 11:43, 10 September 2010 (UTC)

pimelea linifolia......flax leafed riceflower;

does this plant normally be pink? i have two pink ones but i thought they were only white.i am 67 and have never before seen pink. i know there is pink in a different riceflower but this is the flax leafed riceflower & the other is a more rounded leaf. i live on the midcoast, n.s.w. australia02:23, 10 September 2010 (UTC) —Preceding unsigned comment added by 123.208.80.32 (talk)

Our article on Pimelea linifolia says that the flowers are white, but this says that there is a subspecies which can have pink flowers. Smartse (talk) 12:36, 10 September 2010 (UTC)

Polar night and midnight sun

According to the Barrow, Alaska article, the polar night lasts for about 65 days, while the midnight sun lasts for 82 or 83 days. Why are these durations not the same? —Bkell (talk) 02:31, 10 September 2010 (UTC)

The article polar night gives a clue "but in regions that are located at the inner border of the polar circles where midnight sun is experienced, this is not true. Because of twilight, these regions experience polar twilight instead of the polar night. In fact, polar regions typically get more twilight throughout the year than equatorial regions." This implies that "twilight", when the disc of the sun is below the horizon but where the suns light is still detectable, do not count as "night". However, midnight sun must be when the disc of the sun is actually visible. The other 18 days of the year must be times when the sun is just below the horizon; that is not actually visible, but too bright to be considered "night". --Jayron32 03:26, 10 September 2010 (UTC)

See also atmospheric refraction, which makes the sun appear higher over the horizon than it would in a vacuum. PhGustaf (talk) 03:32, 10 September 2010 (UTC)

I thought about atmospheric refraction, but I didn't think it alone could be responsible for that 18-day difference. The discrepancy in the definitions, as Jayron pointed out, seems to be a likely explanation; I hadn't thought of that. Thanks. —Bkell (talk) 03:46, 10 September 2010 (UTC)

In addition to the points mentioned, the Earth is nearer to the Sun during the Northern Hemisphere winter, so it is a few days shorter than the Northern Hemisphere summer. --Anonymous, 03:55 UTC, September 10, 2010.

(edit conflict) Those aren't the only reasons. The Earth's orbit is not a perfect circle, but an ellipse, so, at some points during the year, the Earth is closer to the Sun than others. When is the Earth closest to the Sun? About January 3, right in the middle of Northern hemisphere winter. Now when the Earth is (very slightly) closer to the Sun, it is moving slightly faster around its orbit, a bit like an ice skater who pulls in his/her arms to spin faster. You can see this as well in the dates of the equinoxes: there are about 186 days between the Spring Equinox and the Autumn Equinox, but only about 179 days between the Autumn Equinox and the Spring Equinox. Physchim62 (talk) 03:58, 10 September 2010 (UTC)

One would expect the polar night and polar day to be the same length only if the sun was a point source of light (instead of a circle of about 30 arc-minutes or so), and if the atmosphere did not distort light slightly like it does. I would anticipate that the polar night length and the polar day length would be the same on Pluto if it had the same orbital eccentricity and orbital inclination assuming Pluto has seasons. Googlemeister (talk) 13:02, 10 September 2010 (UTC)

Also, when the Sun is exactly at the horizon, approximately half of its disk is above the horizon, making it bright enough (barring any mountains) to be considered "24-hour sun" if the disk does not go entirely below the horizon. Considering this alone, there would be more days with 24-hour sun than 24-hour darkness. ~AH1^(TCU) 01:20, 12 September 2010 (UTC)

What type of Machine Gun

I vaguely remember a type of Machine Gun I saw long ago. It was one of those type that are kept on ground on a tripod etc. The ammunition is fed by a magazine inserted from above (like most non-portable types). The peculiar thing about this was the fact that when you fire, the trigger-hand handle you are holding moves backword several inches (and the gunner has to keep his elbow-joint supple enough to accommodate the jerk !) Why would they build such a thing ? Does this mean that the gunner has to be ready to have his hand move at least a dozen times per second (when set on rapid fire mode !)  Jon Ascton  (talk) 06:42, 10 September 2010 (UTC)

The only thing I can think of is the woeful French Chauchat light machine gun, where the whole barrel assembly moves (although that is bipod mounted). I believe most tripod mounted weapons are belt-fed rather than having a magazine. You could have a look at this[10] site and see if anything rings a bell. Let us know if you find it! Alansplodge (talk) 18:45, 10 September 2010 (UTC)

I'm not too specific on "tripod", it may have been on a bipod as well (please note "etc"). Yes, I know of models where barrel moves back, but what I am talking about is the hand-grip moving back. I know it sounds weird...

Indoor heating in Florida

Hello, I would like to know at about what winter isotherm does indoor heating start to become common in Florida? Or in the Southern U.S., for that matter. I know that in Southern Florida, around Miami, most people only have small one-room heaters they take out occasionally in January, but I have no idea if the winter temperatures in the rest of Florida warrant a need for indoor heating during most of the winter months. This is my guess, but I imagine Northern Florida would definitely need indoor heating during all the winter months, every year. In general, at about what isotherm or latitude do homes and buildings in the Southern U.S. need indoor heating? Thanks 201.21.183.191 (talk) 12:45, 10 September 2010 (UTC)

This map shows the average 60° isobar in January. Vulnerable people will likely turn on the heating if the temperature drops much below that. Rojomoke (talk) 14:37, 10 September 2010 (UTC)

*Isotherm. Isobars mark pressure. —Preceding unsigned comment added by 92.11.0.210 (talk) 09:37, 12 September 2010 (UTC)

It's only the southernmost part of Florida (Miami and the Keys), which has a subtropical climate, where winter heating *might* be optional - but of course, all that depends on how cool is "cold" to you, and the normal variations of weather. Being a native Southerner, and having lived all over the place from Miami to Atlanta to Texas and in between, I can tell you that people in North Florida definitely run the central heating unit on most days of the winter. Pull up the "climate" section of the wiki article on any major Florida city and notice the temperature chart for the winter months. You live anywhere north of extreme south Florida, and you definitely need regular heating in winter.

Having said that, it's also true that anywhere in the Deep South, say from the latitude of Atlanta or Dallas southward, we *might* actually need to run the air conditioner on any given day of the year, including mid-winter: it's quite normal and routine to get some very warm days (high 70's, even 80's) even in January and February, every year. And then a week or a day later, it might dip down to the 30's or below, and you're running the heat again. That's normal Southern weather. Textorus (talk) 02:16, 15 September 2010 (UTC)

Carrots

I head a long time ago, that drinking excessive amounts of carrot juice could turn someones skin orange. Is that true? Does wiki have an article on it? —Preceding unsigned comment added by Biskyhigh (talk • contribs) 13:47, 10 September 2010 (UTC)

See Carotenosis. --Chemicalinterest (talk) 13:49, 10 September 2010 (UTC)

It's worth noting that the colour of the vegetable has nothing to do with the colour your skin turns. Green vegetables like cabbage can produce the same effect and you don't turn green, you go yellow. Regards, --—Cyclonenim | Chat  14:43, 10 September 2010 (UTC)

Manganese as a free element

Is manganese really found as a free element? It is quite reactive and readily corrodes. I know in some meteorites it may be found, but those are not very common, IIRC. --Chemicalinterest (talk) 14:14, 10 September 2010 (UTC)

The "Occurrence and production" section deals with this Quadrupedaldiprotodont (talk) 14:17, 10 September 2010 (UTC)

Some finds of native manganese have been reported [11], but it is hardly very common. Physchim62 (talk) 14:59, 10 September 2010 (UTC)

PANCREATIC CANCER AND GENOMICS RESEARCH

MY HUSBAND DIED TO PANCREATIC CANCER AND I AM CONCERNED FOR MY CHILDREN AND GRANDCHILDREN. I HAVE RECEIVED INFORMATION FROM NATIONAL FOUNDATION FOR CANCER RESEARCH THAT A DR VON HOFFHAS IDENTIFIED SEVERAL GENETIC WEAKNESSES IN PANCREATIC CELLS. IS THERE ANY WAY THAT MY CHILDREN AND GRANDCHILDREN COULD BE TESTED TO SEE IF THE ARE PREDISPOSED TO THIS DREDFUL DISEASE? I LOOK FORWARD TO HEARING FROM YOU. THANK YOU. —Preceding unsigned comment added by 65.32.133.7 (talk) 15:12, 10 September 2010 (UTC)

Asking a doctor would be a better choice. Most of us are not doctors and might give you bad advice. --Chemicalinterest (talk) 15:26, 10 September 2010 (UTC)

In fact, Wikipedia policy forbids us to give medical advice on the Reference Desks. Looie496 (talk) 15:32, 10 September 2010 (UTC)

It is true that we here on the reference desks can't really answer your question adequately. However, your doctor may not know the answer, either. For the most up-to-date information about genetic risk for cancer, you could look for an MD or genetic counselor who specializes in clinical cancer genetics; this person will know what genetic tests are available and applicable to your family's situation. You can ask your doctor for a referral to a genetics specialist (either MD or genetic counselor). Alternatively, you can search for a nearby genetics clinic here or find a genetic counselor here. --- Medical geneticist (talk) 16:34, 10 September 2010 (UTC)

Wireless USBto

I am planing to buy and use it in India, Warpia, which is a Wireless USB Audio and Video Display adopter set.According to Wikipedia," Wireless USB is based on the WiMedia Alliance's Ultra- WideBand (UWB) common Radio Platform,Which is capable of sending 480 Mbit/s at a distance up to 3 meters and 110 Mbit/s at up to 10 meters. It was designed to operate in 3.1 to 10.6 GHz frequency range, although local regulatory policies may restrict the legal range for any given country". Would this device be compatible in India?Jayessandhu (talk) 17:36, 10 September 2010 (UTC)

muscles shaking

When an athlete finishes a grueling day at the gym, or after a marathon or weightlifting competition, their muscles are often shaky including what might look like shivering. Is this because their muscle has used up its stores of acetylcholine(sp)? Googlemeister (talk) 18:47, 10 September 2010 (UTC)

No, acetylcholine is essentially 'recycled' by your body, at least in the immediate short term. There's a good written explanation here. Regards, --—Cyclonenim | Chat  19:06, 10 September 2010 (UTC)

Your link says it is because certain chemicals produced by the neural motor units can't keep up with demand. That is what I thought, but what specific chemicals? Googlemeister (talk) 19:43, 10 September 2010 (UTC)

I was always under the impression that you don't exhaust acetylcholine, at least not after exercise as it should restore itself with time. Perhaps I'm wrong, or the shakiness is a symptom that occurs until acetylcholine supply recovers. I'll leave this to someone else! Regards, --—Cyclonenim | Chat  19:55, 10 September 2010 (UTC)

The technical term for this seems to be fasciculation. Googling "Fasciculation after exercise" got this link [www.ehow.com/how_5276858_understand-muscle-twitching-after-exercise.html] (which is 'blacklisted' by WP!. The Scientific American link is interesting, but note it is dated 1999 so may well have been made obsolete by newer research, though it sounds quite logical and technically correct. And it does seem they are speaking of acetylcholine.
Calcium is also used in triggering the contraction of muscle fibres (see Sarcomere). I'm wondering if there might be circumstances where it may actually not be a depletion, but an excess of Epinephrine/Adrenaline ? Hope this helps, 220.101 talk^\Contribs 09:01, 11 September 2010 (UTC)

Methane Toxicity

I read an article a couple of days ago (sorry, don't have a link) about a town in Pennsylvania where the ground water was flammable due to the large amount of methane dissolved in it, which the townsfolk blamed on nearby fraking operations. Obviously flammable water presents some large problems, but would it be harmful to drink it (supposing that the only "abnormal" chemical in it were methane)? The methane article seems to deal only with respiration, not ingestion. 96.246.59.38 (talk) 19:32, 10 September 2010 (UTC)

I assume it was a story like this, according to Methane#Potential health effects it shouldn't be dangerous to drink. The water itself can't be flammable though, its the gas that escapes from it that is. If methane is getting into the water, it's likely that other compounds that might be toxic also are though. Smartse (talk) 22:14, 10 September 2010 (UTC)

Very tasty hydrogen sulfide is normally found in methane deposits. --Chemicalinterest (talk) 00:29, 11 September 2010 (UTC)

Wth? Methane is not nearly soluble enough in water to make water flammable. Note that most low-proof alcoholic drinks do not ignite -- and their concentrations are much higher than you would find CH4 in a high-dielectric solvent. John Riemann Soong (talk) 06:07, 11 September 2010 (UTC)

On the other hand H2S has a decent solubility in water -- around 7g/kg during the winter time. John Riemann Soong (talk) 15:14, 11 September 2010 (UTC)

The only way I can think of for methane in water to be flammable is for it to be methane ice. It could potentially be dangerous if significant released methane or carbon tetrachloride(?) from the water in the stomach somehow got into the lungs or if fire swallowing was performed in the presence of the gas. ~AH1^(TCU) 01:12, 12 September 2010 (UTC)

It definitely does happen: [12], as well as an awesome Youtube video: [13]. I don't think the methane is dissolved in the water, but rather flows as bubbles along with the water in the pipes. Buddy431 (talk) 03:00, 12 September 2010 (UTC)

Strength not linked to muscle size?

I'm quite a small guy, 5' 10", slim build, moderately fit.

Recently I discovered that I am stronger than a friend of mine who is 6' 1", weighs 11 stone and has visibly large muscles. What's going on here? He's also moderately fit.--92.251.241.196 (talk) 20:01, 10 September 2010 (UTC)

Two thoughts come to mind : 1) Your friend was being nice, or 2) You chose a 'test of strength' that did not test his 'visibly large muscles' but instead some other muscles that he never works out. APL (talk) 20:49, 10 September 2010 (UTC)

Well as the "test" was a physical fight and we were both angry I think neither of those hold true. He was trying to hit me but was doing no damage, and I pushed him back against a wall and held him, he was also trying to hold his ground but couldn't--178.167.172.73 (talk) 21:41, 10 September 2010 (UTC)

Another thought. I am very thin but someone else that has arms about twice as big beats me in arm-wrestling, but not easily. I can tell he is trying to, so it is not a matter of being nice. I think if muscles are not worked out, sometimes they can stay large but deteriorate internally, and sometimes get replaced by fat. --Chemicalinterest (talk) 21:06, 10 September 2010 (UTC)

Go look at professional athletes like runners. You don't see huge thighs, you see quite thin legs with very lean muscle. Size isn't everything! Regards, --—Cyclonenim | Chat  22:41, 10 September 2010 (UTC)

178.167 - fighting is hugely technique based: a professional Flyweight boxer doesn't weigh that much and isn't that big but I suspect their superior technique would mean they'd have little trouble disposing of someone (lacking the same training) twice their build in a regulation boxing match. Basically size and build are probably correlated with strength but are by no means a guarantee of. ny156uk (talk) 23:00, 10 September 2010 (UTC)

If all else is equal, muscular strength should be proportional to cross sectional area of the muscles, see Muscle_strength#Strength. Also Skeletal muscle. Genetics plays a part of course, you may have more 'fast twitch' muscle fibres allowing quicker application of force. See "Genetic variation in muscular strength" from the British Journal of Sports Medicine - 220.101 talk^\Contribs 09:17, 11 September 2010 (UTC)

The strength (and maybe placement?) of your tendons and ligaments would also make a difference. As would the amount of fat vs protein in your muscles. A 'cushioning' of fat in the muscle fibres increases strength which is one reason why bodybuilders look 'buff' but aren't as strong as strongmen. If your friend works out in order to increase muscle mass he won't increase strength in the same way that somebody who trains for strength would do. Also consider that he may be a 'gentle giant'... even if you're angry he may not consider you a threat. Spoonfulsofsheep (talk) 20:34, 11 September 2010 (UTC)

Pivoting during a strike or hold usually increases the force applied. And for the non-British, one stone = 6.35 kg or 14 pounds. ~AH1^(TCU) 01:01, 12 September 2010 (UTC)

tornado army tank

Is it possible for a tornado too pick up an army tank would it take EF5/F5 status too gain lift. --86.41.129.119 (talk) 20:49, 10 September 2010 (UTC)

An M1A2 tank weighs around 60-70 tons or so and an F5 has had a maximum wind speed of 300 mph. I suspect it would move the tank, but I am skeptical about it picking it up. I wonder if any photos exist of a tornado moving a bulldozer or similar, which might give an indication. Googlemeister (talk) 20:57, 10 September 2010 (UTC)

I did watch storm chasers on the discovery channel and they made a vehicle thats allot like a tank except they had too use something too prevent it from being uplifted so they can go into one but an average tank has nothing like that. --86.41.129.119 (talk) 21:12, 10 September 2010 (UTC)

The vehicles on Storm Chasers aren't truly comparable to a tank in any fashion. I can't imagine they'd top out at more than 5 tons or so; an average tank wouldn't need additional leverage. — Lomn 21:29, 10 September 2010 (UTC)

They could maybe drag it horizontally but there would be no chance of lifting it. Not even a C-130 Herculese or CH-47 Chinook can do that.--178.167.172.73 (talk) 21:56, 10 September 2010 (UTC)

C-130 Hercules is the link you want. Buddy431 (talk) 00:55, 11 September 2010 (UTC)

There is at leas anecdotal evidence of tornadoes being able to lift railroad cars [14], or [15], or [16], for example, but railroad cars are significantly larger, and somewhat lighter than a tank, so that makes the job easier. It's also unclear whether the cars are truly lifted, or rather just pushed off the tracks (still an impressive feat; see this Youtube video [17]. It's interesting that the engine, presumably significantly heavier, manages to stay upright). It also appears that this question has been asked elsewhere, with the general consensus being "no, probably not" ([18], [19], [20], [21]). While none of those sites approach being a reliable source, the comments seem quite reasonable to me. Train cars can be pushed over (and maybe lifted) because they have big sides. Tanks do not. Buddy431 (talk) 01:10, 11 September 2010 (UTC)

One TV account of a southern US tornado said it removed a concrete slab covering a storm cellar. I expect that a strong US tornado might well pick up and whirl around and crash to earth an Abrams tank. There are relatively few Abrams tanks per square mile, so the probability of empirical confirmation of the hypothesis is slight. Instead, do the analysis of a force 5 tornado versus the aerodynamics of the said tank. Could it in principle lift/launch the tank? Edison (talk) 04:40, 11 September 2010 (UTC)

For the sake of a simplified upper bound on what a tornado could lift, consider the following. Suppose the EF5 tornado has a max wind speed of 350 km / hr (100 m/s). Further suppose those winds are somehow capable of blowing directly upward from underneath the tank (very unlikely in practice, but that's why this is an upper bound). The maximum force such winds would impart is of order ${1 \over 2}\rho Av^{2}$ where v is the windspeed, ρ is the air density, and A is the surface area underneath the tank. Taking an M1 Abrams as a representative tank, A is ~30 m^2. For a force of 150000 Newtons, which implies an ability to lift an object up to ~15 tonnes. This is of course well under the 60 tonnes of the tank. So, even given an ideal flow geometry, it is probably impossible for a EF5 to lift a tank. Dragons flight (talk) 06:59, 11 September 2010 (UTC)

They is a big flaw in that as tornado maybe able too do considerable damage from the debris it carries and also it may rip the armor off or the wheels. debris like a 2X4 may get impaled through the armor due too how fast it travels and could shut the engine down or cause the tank too go on fire. Also if the Tornado manages too rip armor off it would be considerable lighter perhaps be more likely also the tornado may have poles, trees, fridges or vehicles like cars or maybe even trucks being whirled around very fast and they gain more energy so they could destroy the tank rather then lift. —Preceding unsigned comment added by 213.94.238.147 (talk) 16:00, 11 September 2010 (UTC)

• Antitank slugs and rockets travel fast too. A 2x4 in a tornado is probably slower, about 200 mph.
• Ripping armor off? The armor is so strong that just a little wind shouldn't rip it off.
• Very few tornadoes produce enough energy to hurl trucks around.

In conclusion, tanks are made to withstand blows stronger than a tornado gives. --Chemicalinterest (talk) 19:54, 11 September 2010 (UTC)

Tanks are not made too withstand a tornado, a EF5 would be able too lift the a truck, the armor is strong enough too withstand little wind, but winds going 350km (an EF5 windspeed) is not little its very strong winds. A 2x4 is not the only thing in a tornado a car or fridges might also be fast enough. --213.94.238.147 (talk) 21:14, 11 September 2010 (UTC)

You could throw cars at a tank all day long and it wouldn't penetrate the armour. They're made to resist ATGMs. A Tornado could do nothing to a tank except damage the extreior systems, tracks and gun. The crew compartment would remain intact and would stay on the ground.--92.251.228.27 (talk) 23:55, 11 September 2010 (UTC)

Debris in the tornado flying in excess of 300 mph would increase any damage done to a tank. These speeds are enough for wooden planks to penetrate concrete. ~AH1^(TCU) 00:55, 12 September 2010 (UTC)

As I said before, antitank slugs travel faster than 300 mph and are stronger than a plank. Probably the penetration of the concrete by the plank is because of the shock which deforms the crystalline structure of the concrete. --Chemicalinterest (talk) 18:46, 12 September 2010 (UTC)

Tanks are made to resist streams of molten metal travelling many times the speed of sound. Debris going 300 mph shouldn't even scratch it.--178.167.229.75 (talk) 19:05, 12 September 2010 (UTC)

The debris as it goes 300mph gains enough energy too possibly penetrate armor of a tank a anti tank slugs mabe faster and stronger but thats just if someone had thrown a plank at a tank a EF5 tornado is amazing possibly even more powerful and strong then a tank and therefore it would possibly easily pick up the tank at some height and smash it back down with considerable force making some bits and pieces break off and therefore the tank become aswell as massive debris it won't be just one 2X4 if you look at the 1999 may oklahoma footage you can see all the debris from that tornado not just 2X4 but things like fridges, cars, trucks, trees these are just normal everyday items are turned into missles and eventually weaken the armor somewhat enough too be blown off and the tornado might atleast kill the driver of the tank. IMO nothing is safe from a EF5 tornado --83.70.106.193 (talk) 20:10, 12 September 2010 (UTC)

Is a ditch 30 feet deep ripped in the ground by an EF5 tornado? If it is, then I will admit that a tank can be ruined by a tornado. Some dirt should be able to be ripped up more easily than thick steel armor. --Chemicalinterest (talk) 20:34, 12 September 2010 (UTC)

During the 1991 Persian Gulf War, an M1A2 tank took a direct frontal hit from a T-72 with the armor remaining intact. A projectile fired from a T-72 has an initial velocity of roughly 3,000 miles an hour, and is more dense then pine. Now, while a 2x4 can do some pretty interesting things when traveling at 300 mph, I don't think it is in the same league as a tank shell when it comes to penetrating power. Googlemeister (talk) 13:35, 13 September 2010 (UTC)

2x4 are not the only debris there are also things like cars, trucks, fridges and other stuff being whirled at 300mph would atleast do some bit of damage perhaps even enough too weaken the armor so that be whipped off and more debris end up damaging the tank from inside also it won't be just be 1 2X4 or 1 car they be allot more then 1 kind of thing in a tornado going into a urban or city area and also i have seen footage of a EF5 tornado actually ripping a house from its foundations. --86.41.130.206 (talk) 17:36, 13 September 2010 (UTC)

What happened to Ron Gellatley ?

Ron Gellatley is an Australian naturopath/medical herbalist/homeopath who wrote a book called 'How to Fight Prostrate Cancer and Win' first published in 1998 when he was in his seventies which apart from the obvious had all sorts of information about herbs and what they do. I'm wondering where he is now as I can't find ANY information about him.121.73.185.217 (talk) 21:03, 10 September 2010 (UTC)

Did you try google? You might want to read this before though. Smartse (talk) 22:01, 10 September 2010 (UTC)

?Prostate cancer

He got shut down. Well I'm just guessing. John Riemann Soong (talk) 15:16, 11 September 2010 (UTC)

Conflicting reactions

The reactions listed at this and manganese(VII) oxide conflict. The specific reaction is the one with concentrated sulfuric acid. The first article says that it produces ozone as a "special" product. The second article says it produces manganese(VII) oxide with some left over ozone. Why do not the two reactions coordinate? Thank you. --Chemicalinterest (talk) 21:26, 10 September 2010 (UTC)

The two descriptions seem coherent enough to me: it's one of those reactions which is "messy", you don't really want to try to write a balanced equation for it, but the products are Mn₂O₇ and ozone, for as long as either of those species stay around. The exact yields of each product will depend on the exact conditions. Physchim62 (talk) 23:35, 10 September 2010 (UTC)

The one in potassium permanganate does not list the very dangerous manganese(VII) oxide formation in the reaction. --Chemicalinterest (talk) 00:27, 11 September 2010 (UTC)

I've tweaked the wording to make it clearer that you can't make ozone by this route without also making manganese heptoxide. Physchim62 (talk) 00:51, 11 September 2010 (UTC)

does Vitamin C increase or decrease the strength of the immune system?

The immune system depends on reactive oxygen species to fight bacteria...so will constantly elevated bloodstream levels of Vitamin C neutralise ROS's? John Riemann Soong (talk) 23:01, 10 September 2010 (UTC)

Have you read Vitamin_C#Immune_system? Rojomoke (talk) 23:43, 10 September 2010 (UTC)

Also relevent, Vitamin C megadosage (a therapy promoted by none other than Linus Pauling) and Megavitamin therapy. --Jayron32 01:45, 11 September 2010 (UTC)

Eating lots of fruit and vegetables is good for you, and includes many other micro-nutrients as well as Vitamin C, but artificially high doses of Vitamin C can cause kidney stones as I know from painful personal experience. 92.29.119.29 (talk) 16:40, 11 September 2010 (UTC)

Also take a look at Antioxidant if you haven't already. Constantly elevated levels of anything would be fatal eventually i think though! Spoonfulsofsheep (talk) 20:55, 11 September 2010 (UTC)

I'm not totally alien to the concept of biochemical redox reactions. My question is -- what prevents high levels of cytoplasmic Vitamin C from annihilating ROSs?

I'm also curious about "paradoxical" interactions; oxidative stress can cause loss in connections between epithelial cells as cells try to "protect" themselves and shut down intercellular connections, but administering hydrogen peroxide at 200 micromolar in a primary astrocyte culture apparently stimulates bridgebuilding by promoting F-actin polymerisation. wtf? John Riemann Soong (talk) 02:57, 12 September 2010 (UTC)

It sounds as if you are closer to the leading edge of research in this area than most of us here at the reference desk. Experts seem to regularly argue, and sometimes change their minds about the effectiveness of high levels of many vitamins. Dbfirs 14:18, 13 September 2010 (UTC)

September 11

Rainbow Falls

Hello. I just made an article on Rainbow Falls, British Columbia. Could someone please find the coordinates of it? --The High Fin Sperm Whale 03:44, 11 September 2010 (UTC)

Looks to be at about 49°23'57"N 121°44'38"W, based on user-submitted information and photos on Google Earth. -- Tom N (tcncv) talk/contrib 04:30, 11 September 2010 (UTC)

So can someone add them to the article?--81.96.185.94 (talk) 08:37, 11 September 2010 (UTC)

BCGNIS search is useful for such things, although the coordinates are rounded to minutes. There are five Rainbow Falls in British Columbia, this one is "Rainbow Falls". BC Geographical Names., I believe. Pfly (talk) 10:30, 11 September 2010 (UTC)

Google maps is your friend Quadrupedaldiprotodont (talk) 14:15, 11 September 2010 (UTC)

Sending nuclear waste to space

I recently watched a TV documentary about how difficult it is to get rid of nuclear waste. So I came to think, what's stopping us from sending it out to space in unmanned throwaway rockets? The only thing that comes to my mind is that it would be far too expensive, but are there other reasons too? JIP | Talk 09:54, 11 September 2010 (UTC)

Impracticality and risk, according to our article's subsection on space disposal. ---Sluzzelin talk 10:01, 11 September 2010 (UTC)

There are two issues:

1. We have a lot of nuclear waste from the space disposal perspective (not necessarily in the "how much waste per unit of energy" perspective). As in 62,500 metric tons of high level waste for the US alone, which is what we are really worried about.[22] (Low-Level Waste is present in far greater volumes, but loses most of its radioactivity over the course of 100 years or so, which is a lot easier to secure from a technical point of view.)

2. Sending things into space has a reasonably high accident rate, ranging from some 5%-15% or so depending on your launch vehicle.[23]

When you combine the two of these, it suddenly doesn't seem like a great idea. To make a significant dent in the waste problem, you have to send up a lot of rockets. How many? If we take the listed payload of a Saturn V, which is huge, it means you would need some 530 launches to get our existing high level waste inventory into just low Earth orbit, without any shielding whatsoever. If we use anything more economical/efficient than that, the number of launches goes up dramatically! That means that at least one of those is probably going to blow up when it is being launched — even if you get the failure rate down to something like 1% (in other words, 99% success), you're still talking about at least 5 major environmental catastrophes, but probably a lot more (since that number of total launches is extremely optimistic and doesn't take into account the fact that the payloads of modern rockets are a lot less than the Saturn V, and the fact that a huge bulk of your mass on each strip would be shielding, even in a minimum-shielding situation). More realistically you're talking about dozens of disasters. That means you're now spreading nuclear waste into the surrounding area. Not good. Of course, you could put some heavy duty shielding in place, right? But now you've just decreased the amount of waste you can send on each trip, meaning you have even more trips, at greater expense.

It's not economical and it's not safe. You're better off, in terms of the tradeoff of risk and expense, just dumping it into a deep sea trench, if you're going to consider doing that.

In any case, the real difficulty in getting rid of waste is mostly a political problem, only in a small degree a technical problem. Or, put another way, the technical problem is the political problem. In the US, for example, the law requires the government be able to certify that absolutely no people in the next 10,000 years or so (at the minimum) will ever have a negative health effect due to this waste. You basically cannot do that, not just with nuclear waste, but anything. It's an absurd standard that we don't hold any other toxic or hazardous substance to, because it's completely impossible to satisfy from a technical point of view, because of the time scales involved. If we were a bit less strict in our standards — that all that was to be avoided was an absolutely worst-case-scenario, and that the waste would be buried somewhere where its being disturbed was unlikely — it wouldn't be such a difficult technical problem.

If there were non-rocket means of getting things into space (e.g. a space elevator), the question might be on the table, but we don't have those yet and it's not clear what their actual performance would be until then. --Mr.98 (talk) 12:12, 11 September 2010 (UTC)

A further issue is that what's now seen as waste might later be seen as a valuable energy source, so sending it beyond easy retrieval isn't a great idea. I think I came across this point somewhere in Sir Arthur C. Clarke's nonfiction writings, or maybe it was Isaac Asimov's, but I can't cite the specific book. --Anonymous, 21:30 UTC, September 11, 2010.

Sounds more like Larry Niven or Jerry Pournelle. --Trovatore (talk) 02:03, 12 September 2010 (UTC)

Well, it's certainly the case that you could get more energy out of the transuranic waste by doing nuclear reprocessing, which is currently not done in the US for political/safeguards reasons. Doing so would also reduce the volume of waste significantly. Other than that, probably not. Waste does generate heat but my understanding is that the energy is not efficient enough for practical usage, once you add in all of the radiation protection issues. --Mr.98 (talk) 23:45, 11 September 2010 (UTC)

I've heard of Sodium_reactors designed make energy by `burning' what is currently considered waste, but our I don't see mention of this in the article.SemanticMantis (talk) 01:37, 12 September 2010 (UTC)

Well, it does say they'd use a closed fuel cycle with lots of reprocessing, so that is probably what is meant. You can't just put raw waste into a reactor; it won't fission correctly (there are fission products that have a "poisoning" effect on the reaction), and the radioactivity is too high for anything but very circumspect handling. But if you strip out the left over uranium and plutonium from the waste, you can use that. That's what reprocessing does. Again, in the US, in particular, we treat spent fuel as "waste." We could treat it as feed for reprocessing. We stopped doing that in the 1970s because of fears that it would create a large volume of weapons-usable plutonium that would be hard to account for (or, put another way, if you have a large reprocessing plant, like the Rokkasho Reprocessing Plant in Japan, you will inevitably have some % of fissile material loss unaccounted for, which makes an ideal situation if you were trying to steal enough fissile material for a bomb). --Mr.98 (talk) 12:38, 12 September 2010 (UTC)

on your no-injury-in-10,000-years claim? Comet Tuttle (talk) 12:51, 12 September 2010 (UTC)

Well, I did simplify it a bit, because the actual regulatory requirements are complicated (and in fact, which regulatory requirement matters is complicated, because there are at least three agencies with possible jurisdiction over this—EPA, NRC, and DOE). But it was in the late 1970s that the EPA set a requirement that any "reasonably foreseeable" release should not exceed "one chance in a hundred in 10,000 years", and that any major accident should be "virtually impossible" and thus not exceed one chance in a million over 10,000 years. The NRC argued that this was basically an impossible level of precision to require over that time scale. In 2004, though, the US Court of Appeals ruled that the EPA was required by law to set radiation standards not just for 10,000 years but for a million (!) years. In 2008 the EPA came up with rather specific standards for exactly what the radiation release at a place like Yucca Mountain must be for the next million years, and the NRC/DOE has to be able to certify that any storage method can meet them. Long discussion of some of these technical rulings with an emphasis on the recent ones here: [24] Anyway, as you can probably tell, I think this is all kind of nuts, as if we can predict with any reliability anything on Earth for the next million years, much less something as complicated as the long-term disposition of radioactive materials. It's a regulatory nightmare. Anyway, the original concern regarding 10,000 years (which is already crazy, much less a million years), came from a EPA estimate that the Yucca Mountain site would cause between 100-1000 fatal cancers over 10,000 years (that is, one fatal cancer every 10-100 years), which is somewhat what I was referring to before in a shorthand way. My citation for all of this are notes I took awhile back on J. Samuel Walker's The Road to Yucca Mountain, chapters 5 and 8. --Mr.98 (talk) 14:35, 12 September 2010 (UTC)

contradiction in electromagnetism

Notice the curved and spiral paths of the charged particles in this bubble chamber photograph. This is due to the magnetic field of the charged particle interacting with the magnetic field of the chamber.

I have one doubt. When two similar charges are kept at a distance and if our reference frame is not moving and charges too are not moving then they repel each other. If our reference frame starts moving lets say backward from charges with some speed, then we see that charges are going away with same speed. Because charges are moving, they will create magnetic field and we should see that they attract each other (because they are moving in the same direction with respect to us.) According to me this is a contradiction. Just because of changing our reference frame how can phenomena change? Change in reference frame should not change the phenomena. —Preceding unsigned comment added by Ptamhane (talk • contribs) 10:01, 11 September 2010 (UTC)

For a charge to induce a magnetic field, doesn't it have to be moving through a conductor? Not just a "frame of reference"? Vespine (talk) 11:18, 11 September 2010 (UTC)

No, fundamentally magnetism is a relativistic effect, the electric field is (partially) transformed into a magnetic field by the moving frame. The effect is easier to understand if two lines of charges are considered instead of two isolated charges. The distance between the charges in each line will be reativistically foreshortened in a moving frame. Two lines moving in opposite directions will measure (in a frame moving with one line) the distance between charges in the other line as being less, and consequently a greater charge density leading to a greater repulsion. Two lines moving in the same direction will have less repulsion, as observed by a frame at rest. These adjsutments to the electrostatic force are the root of magnetic forces. SpinningSpark 13:06, 11 September 2010 (UTC)

You just made my brain hurt.. Vespine (talk) 13:28, 11 September 2010 (UTC)

Not to contradict any of that (which I actually don't understand, I'm afraid), but it might help to add that electromagnetism is governed by Maxwell's equations. When Einstein developed Special Relativity, his primary motivation was to find a space-time transformation that kept Maxwell's equations valid in moving reference frames. They are not valid in moving frames in Newtonian mechanics, though. Looie496 (talk) 18:21, 11 September 2010 (UTC)

See also, Liénard–Wiechert potential, which describes the magnetic field of moving charges; and Covariant formulation of classical electromagnetism, which describes the way that the Maxwell Equations bridge the gap between classical and relativistic mechanics. Nimur (talk) 09:01, 12 September 2010 (UTC)

When charge line A is moving in the same direction parallel to charge line B, they have relatively normal repulsion, but when the lines are moving parallel in opposite directions...the "charges" in line B relative to line A (observer) experience a form of electromagnetic redshift, so that the line B relative to itself undergoes length contraction, causing both lines to have a stronger "repulsive" force relative to each other, making the repulsion stronger? Is this close to the description above? ~AH1^(TCU) 00:45, 12 September 2010 (UTC)

Horseshoe Crabs

The article on horseshoe crabs says that they are over-harvested. But who harvests horseshoe crabs and for what? —Preceding unsigned comment added by 69.120.0.81 (talk) 12:04, 11 September 2010 (UTC)

Ummm, Your question is answered in the very same sentence.. I'll give you a hint: East coast of North America and fertilizer and bait. Vespine (talk) 12:32, 11 September 2010 (UTC)

Actually the answer is also partly in the Blood section. It turns out that horseshoe crabs have very weird blood that contains a unique substance that is a very sensitive detector of bacterial contamination, which makes it extremely valuable to the biotech industry. There was an episode of the PBS show Nature devoted to this in 2008, which can be viewed online. Looie496 (talk) 18:14, 11 September 2010 (UTC)

Could a knowledgeable editor add such relevant material to the Blood section of the article? That section is currently a little short and vague. Comet Tuttle (talk) 12:45, 12 September 2010 (UTC)

There is some referenced info in the article on limulus amebocyte lysate. ---Sluzzelin talk 12:53, 12 September 2010 (UTC)

Helium shortage

If we're running out of helium, why can't we make some more by taking radioactives (and we have plenty, via nuclear waste), and then putting them in an atmosphere. It seems like they would spit off enough alpha particles for this to be useful. Alpha particles + other stuff = slightly ionized other stuff + helium. —Preceding unsigned comment added by 69.120.0.81 (talk) 12:09, 11 September 2010 (UTC)

One problem is that the most radioactive bits of nuclear waste are not alpha emittors. Another is the scale that would need to work on. World helium production in 2009 was about 29,000 tonnes, or 7.23 gigamoles. As helium-4 has relative atomic mass 50–60 times less than that of most alpha-emitting nuclides, you would need 1–1½ million tonnes of alpha-emitting radioactive waste to decay each year to supply the world's helium consumption. Physchim62 (talk) 12:48, 11 September 2010 (UTC)

ARE we running out of Helium? The article says "Helium is the second ... most abundant [element] in the observable universe". Also it doesn't burn, so how is it being used up then?? Quadrupedaldiprotodont (talk) 14:12, 11 September 2010 (UTC)

It's not that we're running out, it's that we cant produce it as quickly as we use it up. While it is abundant in the universe, it's not certainly not freely abundant on earth, it only makes 0.000524% of our atmosphere. Vespine (talk) 14:18, 11 September 2010 (UTC)

If we were using the helium from the atmosphere, there wouldn't be a supply problem, but we're not: we're using helium which has accumulated in natural gas deposits, which is much much cheaper to separate. What we're running out of is cheap helium. Still, as the price rises, helium recycling becomes more and more cost effective and helium will stop being used for applications where argon can do the job just as well. I think we will see some pretty efficient helium recycling long before we see significant quantities being extracted from the atmosphere. Physchim62 (talk) 14:51, 11 September 2010 (UTC)

Unfortunately the sell-down of the Strategic Helium Reserve is artificially depressing the price. Hopefully the market will anticipate the end and cushion the blow. But helium is so hard to keep as inventory that I don't know that it will. --Trovatore (talk) 04:10, 12 September 2010 (UTC)

... ah, apparently it's called the National Helium Reserve. I was mixing up the name with the Strategic Petroleum Reserve. --Trovatore (talk) 04:12, 12 September 2010 (UTC)

This story did the rounds recently [25] (reprinted in numerous other papers) as did other articles [26] apparently partially a result of a? talk at the Nobel Laureate Lectures at Lindau which could be what got the OP thinking. BTW, as mentioned in our article helium which is released to our atmosphere is eventually lost to space in what's considered a relatively fast time. The current low level in the atmosphere is the result of the natural balance of helium arising from decay and helium that escapes. This is evidentally something that gives YEC wet dreams because they claim the level proves the earth is young. Nil Einne (talk) 06:44, 12 September 2010 (UTC)

Lonely

What is the science behind lonely people? Why are some people socially retarded and lonely, unable to get a girl/boy friend? Is it evolutionary? —Preceding unsigned comment added by Friend4u772 (talk • contribs) 13:26, 11 September 2010 (UTC)

This is covered at Loneliness#Common causes Regards, --—Cyclonenim | Chat  13:29, 11 September 2010 (UTC)

See social alienation and unrequited love. ~AH1^(TCU) 00:15, 12 September 2010 (UTC)

Extended content

Personal attack removed Nil Einne (talk) 09:28, 12 September 2010 (UTC) "Personal experience" isn't particularity helpful when the OP asked for scientific reasons. 79.163.124.125 (talk) 11:11, 12 September 2010 (UTC) See Recluse, isolation, solitude, and seclusion.Smallman12q (talk) 14:19, 12 September 2010 (UTC) Personal attack removed Nil Einne (talk) 19:26, 12 September 2010 (UTC) Is that a personal attack?Smallman12q (talk) 23:48, 12 September 2010 (UTC) Whatever it is, it's pointless troll feeding and not helpful to the OP. 99.18.82.80 (talk) 23:51, 12 September 2010 (UTC) Those comments by Nil Einne are completely inappropriate, I think they deserve a caution. Vespine (talk) 01:22, 13 September 2010 (UTC) Support. "Caution, Nil!" WikiDao (talk) 01:52, 13 September 2010 (UTC)

Struck posts not relevant to answering question. Franamax (talk) 02:06, 13 September 2010 (UTC)

Insulating magnets

What are the possible ways/tricks to insulate magnets? One way I've been thinking about is producing an opposite magnetic field but not sure if it works. --Email4mobile (talk) 13:39, 11 September 2010 (UTC)

If by insulating magnets, you mean shielding its magnetic field, the most common way would be to use high permeability materials as a shield. See for example Mu-metal. --Polaron | Talk 13:57, 11 September 2010 (UTC)

Also check out Electromagnetic shielding#Magnetic shielding. 88.112.56.9 (talk) 14:00, 11 September 2010 (UTC)

Perhaps coat it in thick cement Quadrupedaldiprotodont (talk) 14:09, 11 September 2010 (UTC)

Concrete has a fairly low magnetic permeability, a property that makes it a poor shielding material. "Thick" is helpful because a magnetic field weakens as you get far from it, but the concrete itself is no more effective than air, and much less effective than steel or many other common shielding materials. DMacks (talk) 18:39, 11 September 2010 (UTC)

Lifting heavy weights = nerve failure

I used to do a lot of weightlifting when I was in my teens (about 20 years ago.. so this isn't a request for medical advice lol) and I once did a phase of lifting very heavy weights. It was more powerlifting really, low rep compound exercises at near my max lift weight, I think it was based on doing 3 sets of 3 reps at near the maximum weight one could lift to build up strength as quickly as possible (rather than muscle size). Not long into the training I did a session when I suddenly couldn't grip the barbell properly let alone lift it. A guy at the gym explained what it was but I'm trying to remember the exact name for it. I think it's something to do with overloading the nerves that control your muscles. And it's temporary, whatever the cause you recover quickly in the same way that lactic acid causes an athlete to stop to recover before starting again. Can anybody point me to a link please? 84.93.187.219 (talk) 18:18, 11 September 2010 (UTC)

You could try looking into the articles on Paresthesia or Hypoesthesia or Obdormition (the second and third are more of stubs). The Somatosensory system is in charge of sensations like this, so you may find something there. Better yet, you should talk with a medical professional; perhaps an athletic trainer given the nature of your question, or perhaps a doctor. If something unexpected happens to your body in this way, you shouldn't take the advice of a random dude at the gym, or random dudes at the internet. Ask, in person, someone who has the actual training and certification to answer intelligently. --Jayron32 04:15, 12 September 2010 (UTC)

I appreciate the links, they didn't answer my question though. To be clear I'm not asking for advice about the condition, I want to remember what the condition is called. The guy who explained what had happened knew what he was talking about and I researched it at the time, it had a specific name. You know when you have something that you're trying to remember and it really winds you up? This is one of those times! Spoonfulsofsheep (talk) 16:26, 12 September 2010 (UTC)

I think I'm close to an answer with help from wikipedians . It's related to central nervous and peripheral nervous system fatigue. I still haven't found the specific term tho! 87.115.9.84 (talk) 17:05, 12 September 2010 (UTC)

Fasciculation? Physchim62 (talk) 19:40, 12 September 2010 (UTC)

Ah, it's not fasciculation (probably the opposite actually) but it's related to what I was thinking and put me in the right direction thanks! It's a bit more complex than I remember from 20 years ago which may be why I couldn't find it via google. Wikipedia touches on it in Weakness#Differential_diagnosis, specifically 'For extremely powerful contractions that are close to the upper limit of a muscle's ability to generate force, nervous fatigue can be a limiting factor in untrained individuals. In novice strength trainers, the muscle's ability to generate force is most strongly limited by nerve’s ability to sustain a high-frequency signal. After a period of maximum contraction, the nerve’s signal reduces in frequency and the force generated by the contraction diminishes. There is no sensation of pain or discomfort, the muscle appears to simply ‘stop listening’ and gradually cease to move, often going backwards'. Tx all! Spoonfulsofsheep (talk) 20:51, 12 September 2010 (UTC)

That's a little scary! Can it happen suddenly, as in the weight could nearly free-fall on you? I frequently work with up to 200 lbs or so without a spot (I leave the collars off so that I can dump the weight if necessary). --Trovatore (talk) 22:07, 12 September 2010 (UTC)

You see something very similar to "weights in free-fall" in many weight-lifting competitions... Physchim62 (talk) 23:22, 12 September 2010 (UTC)

Barring an underlying condition the answer is no, but you obviously shouldn't use weights without a spotter! This condition is specifically about lifting something close to your max weight in the 1-3 rep range (in rapid succession) for strength training that causes the nerve signal to the muscle to wear out before the actual muscle is fatigued. If you're doing typical weight training or bodybuilding there will be a number of other factors that stop you exercising other than nervous fatigue, 'muscle burn' being an obvious contender. 87.115.119.136 (talk) 23:33, 12 September 2010 (UTC)

Orbital overlap

We don't seem to have an article on this rather fundamental concept in chemical bonding. Or do we? How would you describe it non-mathematically? Is is still as relevant as it used to be, now with the rise in density functional theory methods? Physchim62 (talk) 19:23, 11 September 2010 (UTC)

I might be wrong, chemistry isn't my strong point, but molecular orbital diagram seems to discuss a little about this. Might be worth checking out. Regards, --—Cyclonenim | Chat  22:43, 11 September 2010 (UTC)

You may also be interested in valence shell. ~AH1^(TCU) 00:10, 12 September 2010 (UTC)

The orbitals overlap by hybridizing which is part of valence bond theory.--72.152.236.190 (talk) 01:23, 12 September 2010 (UTC)

The statistical mechanics of Schroedinger wave interactions, charge boundary interactions, and phase boundary interactions also pertain to orbital hybridization. 208.54.5.55 (talk) 03:40, 12 September 2010 (UTC)

Applications for chemicals

Does anyone have any good references for finding the applications of a chemical? For example, I can see that thiodiglycol is used as a solvent, but I'd like to learn about ALL (or more!) of the applications for that chemical. Where would I look for those applications? Clearchemistry (talk) 21:47, 11 September 2010 (UTC)clearchemistry

can you narrow your quest down. What do you want to know for? For instance there are books like [27] but does this address your thirst?--Aspro (talk) 22:11, 11 September 2010 (UTC)

What do you mean? The OP has clearly stated what they want: information about the applications of thiodiglycol. I presume you've read our article on the chemical. The main use I find by Google searching is it's use as a precursor to mustard gas, though I doubt (and hope!) you won't be using it for that purpose. This link has a nice section on it's other applications and properties. Regards, --—Cyclonenim | Chat  22:41, 11 September 2010 (UTC)

Perhaps not clear enough. It looks to me that the question-asker is looking for a general resource to go with this sort of question. The Thiodiglycol is just an example. APL (talk) 07:59, 12 September 2010 (UTC)

Well mustard compounds can be used as anticancer drugs...no? John Riemann Soong (talk) 03:41, 12 September 2010 (UTC)

September 12

Density of methane clathrate and formation thermodynamics

Why is the article on methane clathrate so unhelpful and only giving one sig fig for the density? It doesn't tell me whether methane clathrate is more dense or less dense than regular ice. Google doesn't appear to help because all the hits cite Wikipedia figures. -_-

See, I don't know why higher pressures should induce clathrate formation -- I mean, if it's less dense so shouldn't it discourage clathrate formation? John Riemann Soong (talk) 03:39, 12 September 2010 (UTC)

This paper shows a phase diagram for the system which may be helpful. Mikenorton (talk) 03:55, 12 September 2010 (UTC)

If you don't like our article on methane clathrate, you could always do a little bit of research and improve it... And as methane clathrate is about 1300 time more dense than gaseous methane, of course pressure would favour its formation. Physchim62 (talk) 12:28, 12 September 2010 (UTC)

Ooops, I guess I forgot there was a CH4 + water system -- I mean, so the ice sacrifices a little density for much improved density in methane? John Riemann Soong (talk) 17:17, 12 September 2010 (UTC)

TV

Do mini tvs use LDC screens, or cathod ray tubes? —Preceding unsigned comment added by Creivler (talk • contribs) 13:08, 12 September 2010 (UTC)

Modern handheld televisions use either LCD or OLED displays. The MTV-1, an early miniature television, is about as small as you can get with CRT technology. Gandalf61 (talk) 13:34, 12 September 2010 (UTC)

Ants

When my worker ants die, why do they always lie on their backs with their legs in the air? I've noticed this in almost every death of my worker ants. Is it some evolutionary result of making the dead easier to carry and remove from my nest by the living workers? JennyTheQueenAnt (talk) 13:19, 12 September 2010 (UTC)

Species info would help if you have it. Are you watching them roll over, then die? Otherwise, I'd guess they die standing up, then get rolled over when their legs curl up (dessication/ rigor mortis?). But it could be an adaptive behavior. Some species will `intentionally' leave the nest when they are infected, so that their bodies won't be a source of further infection for the colony. SemanticMantis (talk) 14:02, 12 September 2010 (UTC)

Can I get pregnant even if i had a postinor 2 tabs( within 48 - 72 hours)

This question has been removed. Per the reference desk guidelines, the reference desk is not an appropriate place to request medical, legal or other professional advice, including any kind of medical diagnosis or prognosis, or treatment recommendations. For such advice, please see a qualified professional. If you don't believe this is such a request, please explain what you meant to ask, either here or on the talk page discussion (if a link has been provided). DMacks (talk) 17:31, 12 September 2010 (UTC)--DMacks (talk) 17:51, 12 September 2010 (UTC)

Even a doctor wouldn't attempt to diagnose a pregnancy based solely on the question posted. Some general information about the issues involved, followed by a recommendation to see a medical professional for an actual diagnosis and treatment recommendations, would be more helpful than "Go away!". Peter Karlsen (talk) 17:46, 12 September 2010 (UTC)

Feel free to discuss on the talk-page. DMacks (talk) 17:55, 12 September 2010 (UTC)

September 13

Question about the flare-drop scene in Waterworld...

In Waterworld, the bad guys own the Exxon Valdez and keep a little white fella down in the petroleum well to check the levels. I realize this is fiction, but bear with me here for two legit science questions: 1) assuming the little white guy down in his skiff is really in a massive tank, adrift in a sea of oil, would he be able to breathe or would the fumes overpower him? 2) when Kevin Costner drops the flare down the vent pipe into the oil, would the oil really ignite in real life? I seem to recall that certain "flammable" substances can't actually be lit with a tossed match... Masked Booby (talk) 01:44, 13 September 2010 (UTC)

For Q2, our flash point and flammability limit articles may help you. Ring back if you have more questions. Franamax (talk) 02:15, 13 September 2010 (UTC)

Flares burn quite hot, so it's not like you're tossing a match in there. The movie, on the other hand, has some very questionable "science" in it. For example, where the hell did they find enough water to raise the sea level several miles???--Dr Dima (talk) 02:28, 13 September 2010 (UTC)

To your original question, you can certainly have a mixture of methane and air that is breathable but may detonate if ignited; see coal mining and firedamp. Regarding crude oil, or whatever the stuff down there was supposed to be, I do not know if you can have fume concentration high enough to detonate when lit but not high enough to croak the fella. I seriously doubt Kevin Costner ever thought of that. --Dr Dima (talk) 03:00, 13 September 2010 (UTC)

For Q1, depends on the "oil" and time of exposure. If it is crude oil aka petroleum, still depends, but much less so. Crude petroleum is a mixture of volatile and relatively much more stable fractions. A super-heavy crude would produce relatively less airborne fractions. But what if was actually asphalt in the tanker? You might just get a really bad headache. Or sour crude oil, in which case you will die shortly after you stop noticing the rotten egg smell. In general though, if you are thinking of entering a confined space where hydrocarbons are or were recently present, if you aren't using PPE, expect to die. Even if it was just cleaned, the space might have been purged with nitrogen gas and you will still die. Franamax (talk) 03:12, 13 September 2010 (UTC)

Because of the context of the movie, if a human can mutate to breath water, there is no reason to assume that human could not mutate to easily breath oil/gas fumes. -- kainaw™ 03:17, 13 September 2010 (UTC)

Parabens in Shampoos

Which shampoo brands have Paraben and which shampoo brands don't have Paraben? 174.114.236.41 (talk) 04:13, 13 September 2010 (UTC)