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Is ] a recognized disability in the United States of America? Can one get disability payments for it? How do they weed out people faking it for free welfare money? ] (]) 20:19, 11 April 2015 (UTC)
Is ] a recognized disability in the United States of America? Can one get disability payments for it? How do they weed out people faking it for free welfare money? ] (]) 20:19, 11 April 2015 (UTC)
== inducing sleep paralysis ==
Is there any reliable and repeatable way to induce sleep paralysis in a human being? Like how . Thank you ] (]) 20:42, 11 April 2015 (UTC)
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If you push your face against the door of a microwave to watch the food going around inside, how much dose of radiation do you get? — Preceding unsigned comment added by Coosquirt3 (talk • contribs) 00:53, 7 April 2015 (UTC)
Literally nothing, if you mean ionizing radiation, which is the stuff that causes real issues. Microwave ovens do not produce ionizing radiation, which is what causes cancer and radiation sickness and stuff like that. Microwaves emit a high-energy form of radio waves, not much different from the signal that is picked up by your TV set if you receive an over-the-air broadcast. According to this, the average microwave oven "leaks" about 2 milliwatts per square centimeter at a distance of 2 inches from the glass over the whole lifetime of the microwave total. Assuming a microwave lasts ten years, 2 milliwatts per square centimeter per decade is basically next to nothing. --Jayron3201:09, 7 April 2015 (UTC)
Your response is susceptible to a misunderstanding. Milliwatts are units of energy flux, not total energy. The meaning of the FDA standard is that the flux (i.e., rate of energy leakage) can't increase beyond a certain limit (5 mW /cm2) as the oven gets older. This is not necessarily related to the accumulated flux over time, which would be measured in joules per unit area. Short Brigade Harvester Boris (talk) 01:31, 7 April 2015 (UTC)
Yes, microwaves are designed to be safe. The glass door has a mesh that prevents leakage of sufficient microwave radiation to cook your eyeballs, but I wouldn't recommend spending many minutes with your eyes pressed against the glass, just in case ... Dbfirs09:15, 7 April 2015 (UTC)
No. Again, ten times no. Microwaves do not ionize anything. Microwaves are not ionizing radiation. Microwaves do not do to your cells what things like X-rays and gamma rays do. --Jayron3216:45, 7 April 2015 (UTC)
LED and CFL bulbs cut on and off 60 times per second right (on US A/C). How long do they stay on in each cycle?
Yesterday I took three photos that included a street lamp. The exposure time was 1/400 second. In two of the photos, the street lamp was very dim but in the third it was brighter than I remember it being.
I don't know, but I do know that "60 times per second" is wrong unless the light is only on when the AC current is flowing one way and not the other way. Any such flicker should normally be at 120 times per second. --65.95.176.148 (talk) 03:27, 7 April 2015 (UTC)
An LED may not flicker in both directions. Current tends to only easily flow in one direction through a diode. I'd think that'd keep them at 60 Hz. --OuroborosCobra (talk) 03:57, 7 April 2015 (UTC)
Most modern fluorescent lights use an electronic ballast that changes the frequency to to something on the order of tens of kHz. LED bulbs don't turn off and on at all. They use a rectifier to supply the actual LED with DC. Any flicker is just a result of the driver circuitry not smoothing the output very well. Mr.Z-man04:07, 7 April 2015 (UTC)
Bet me to it, even cheap LED bulbs will have a rectifier circuit in them, I have actually used them as a cheap source of 12v rectifiers for other projects. Vespine (talk) 04:22, 7 April 2015 (UTC)
I've added cropped versions of three photos that I took the other day within seconds of each other. I didn't notice any change in brightness. They were all taken in aperture priority, ISO 100, f/8. (the first one was at a focal length of 60mm, the next two were at 70mm.) The camera exposed the first and third for 1/320 second and the second one for 1/400 second. Yet, the second one is brighter, even though its exposure was shorter. Why? Bubba7305:14, 7 April 2015 (UTC)
The lamp in question could very well be flickering, that would explain the different brightness. We're making a lot of assumptions. MY guess is that it isn't an LED lamp, but have no good guess as to what it is. I suppose some sort of fluro makes the most sense. Could you take some more photos, maybe manually set the exposure to 1000th and see what it looks like? also take some photos of OTHER lamps in the area, in case the one you picked just happened to have a faulty driver perhaps flickering because it's "on the way out"? That's probably unlikely, but might be worth eliminating as a factor. Vespine (talk) 06:51, 7 April 2015 (UTC)
Flickering fluorescent lights are a fairly well known problem in photography. See here for example. Modern DSLRs can include anti-flicker circuitry. Check out the review of the Canon 7d Mk II at the same site for a description of it in action.--Phil Holmes (talk) 10:05, 7 April 2015 (UTC)
My camera (Nikon D7100) as the anti-flicker and I have it on. However, the lamp is only a small portion of the entire photograph, so it may not have picked it up. Bubba7315:24, 7 April 2015 (UTC)
I would like more info on this. The OP asks about LED, CFL, etc. These photos look like one of the 'etc' bulbs. I.e., common incandescent. What color balance did you use (AWB?)(and there are sky clouds clearly visible behind so me thinks AWB) ... its reddish, so not a LED nor fluorescent. Its light flux is just varying 120 times per second. --Aspro (talk) 15:12, 7 April 2015 (UTC)
In my WP:OR, it is rather hard to get two identical photos, even with a tripod, with a modern digital camera on "auto/normal" modes. The white balance, autofocus, and lots of other factors conspire such that even in controlled situations where you know the subject and light haven't changed, the photos can still look rather different. SemanticMantis (talk) 15:42, 7 April 2015 (UTC)
Forgetting the specific terminology of your camera, I just meant this - "Yes, I did have auto white balance on, and it was set to normal" - that means the camera was making at least a few choices on your behalf, that may well change the apparent brightness in the photograph. SemanticMantis (talk) 18:06, 7 April 2015 (UTC)
Here are 32 shots of the same lamp taken over the period of less than 1 minute. This was done in manual mode, 1/1000 second, f/2.8, so the camera isn't doing any fiddling with the exposure. They show that there are times when it is bright and times when it is dim. Bubba7301:26, 9 April 2015 (UTC)
CCFL use an inverter. LED a current regulated buck converter which is supplied by rectified and filtered AC input. The unfiltered 120 Hz would be a visible stroboscope, but some converters pulse a higher frequency instead of regulated current. --Hans Haase (有问题吗) 18:46, 9 April 2015 (UTC)
Modern medicine / human evolution
To what extent does modern medicine undermine natural selection in humans, thereby hindering human evolution? ―Mandruss☎11:48, 7 April 2015 (UTC)
This is a hard question. We can't really do controlled experiments, and there's no generally applicable method of quantifying the "strength" or "speed" of evolution. Here's an article that discusses the problems with studying human evolution, and points to newer methods in genome studies and haplotype structure as a way forward , and here's a more recent article by some of the same authors: . The point is, these are relatively recent papers in Science and Nature, and we are a long way from having robust and widely accepted methods and results. A few things to keep in mind: Selective pressure will usually act the fastest when it acts at a life stage prior to sexual maturity. Now, some medical treatments save children that would have otherwise died without, but many medical treatments are applied to people who have already reproduced, or may never, and these don't have as strong of an effect. Here's an article that briefly mentions human impacts on human evolution, but it's mostly about human impacts on evolution in general . Now, there are some ways that pressures after reproductive age can influence evolution - notably kin selection and group selection. This recent work on orcas points out some similarities with humans - we are some of the few species where females survive and hang around after menopause. Now, humans did that before modern medicine, but it hints at how culture and sociology can influence evolution via mechanisms different from classical Darwinian selection. Finally, this book seems to have some discussion closely related to your question, but I have not read it. So - no real answers here, but lots of refs. SemanticMantis (talk) 15:02, 7 April 2015 (UTC)
There's also the false dichotomy between the natural and unnatural. Environmental pressures effects evolution. Period. Modern medicine is an environmental pressure which effects human evolution. Nothing else needs to be understood by introducing spurious ideas like "natural" and "unnatural". The question makes more sense if you merely asked "What sorts of evolutionary pressure is introduced to the human species by modern medicine?" --Jayron3216:42, 7 April 2015 (UTC)
I agree with Jay. Selection pressures are changing, but they are not going away. So evolution will continue to do its thing. Consider moles - by digging underground they stop being preyed on by birds of prey - that means that that evolutionary pressure is reduced, but others come into play (less vision, better sense of smell, better sensing of vibrations, better burrowing). It's similar with humans - we can now treat some conditions that would previously be deadly, but that does not mean that all people have the same reproductive success. It's hard to tell which features currently are selected for, but that does not mean that none are. Richard Dawkins's The Extended Phenotype has some interesting ideas on the interaction of populations and how they modify and interact with their environment. --Stephan Schulz (talk) 16:54, 7 April 2015 (UTC)
For a species with generation length as long as humans, selection pressure has to be sustained for thousands of years to have a significant impact. In far less time than that we will be able to engineer the human genome from top to bottom. So it really doesn't matter at all. Looie496 (talk) 17:21, 7 April 2015 (UTC)
I believe a better question would be: Is there any form of selection pressure in humans? Selection pressure would increase the likelihood that one set of humans would produce offspring while reducing the likelihood that another set of humans would produce offspring. Other than young death, I've only seen respectable studies linking lack of education and poverty to an increase in the number of offspring, but not to the likelihood of producing offspring. 209.149.113.89 (talk) 19:04, 7 April 2015 (UTC)
Sexual selection is a mechanism that evolved over hundreds of millions of years to keep evolution from going off the rails when for prolonged periods important selection mechanisms are absent. E.g. if prey animals live for many generations in an area where predators are absent, sexual attraction will still lead the fitter animals to contribute to the gene pool. Count Iblis (talk) 20:04, 7 April 2015 (UTC)
Well, it just seems logical to me that sexual attraction will, in general, have evolved to enhance the survival of the next generation. The article on sexual selection is a bit misleading because the evidence for sexual selection is most apparant in the rare cases where sexual preference leads to offspring with features that are of no benefit. This then leads to the evidence that sexual selection is a factor these cases, but of course, this is not how it works in general. Count Iblis (talk) 21:06, 7 April 2015 (UTC)
Sort of. But come on, you have some science training, right? You should know that your notion of logic applied to an area that you are not specifically trained in is not a reference. Sexual selection is in no way something that generally increases fitness in the absence of other pressures. Many aspects of sexual selection, and the interaction with other selective pressures are still very poorly understood, and very active areas of research, please don't fall in to this trap :) SemanticMantis (talk) 15:58, 8 April 2015 (UTC)
Infectious disease is believed to be the greatest evolutionary force in humans, from sickle-cell anemia to smallpox, to cholera causing the evolution of multiple sclerosis. It has also been suggested that shortsightedness among the Chinese is linked to their long history of agriculture (where one need not spot and sneak up on the prey from a distance) and modern medicine has removed much of the burden of things like type-I diabetes and problematic childbirth, which will lead to people who otherwise wouldn't have survived to reproduce passing on problematic genes. μηδείς (talk) 20:21, 7 April 2015 (UTC)
My question was prompted by an earlier thread at WP:RDM, in which the issue of infant cranial size vs birth canal size was mentioned. I don't think there's any disputing that this problem has resulted in the deaths of many mothers (and infant girls), but far fewer after the development of relatively safe C-sections and other things. It seems intuitive that, without the interference of modern medicine, the problem would eventually correct itself. Aside from Looie496's point, which would render this purely academic, is there any validity to this? Is the idea that with modern medicine this should cease to be viewed as a "problem"? ―Mandruss☎02:20, 8 April 2015 (UTC)
Also recall that C-sections are not readily available to all. I have no idea what the access rates are, but I suspect rather low outside rich countries, and most of the human population is part of the global poor e.g. SemanticMantis (talk) 19:52, 8 April 2015 (UTC)
It has gotten to the point where certain domestic animals regularly require veterinary assistance to give birth. In the past, if a woman was genetically ill-suited to give birth due to small hips, she would not pass on those genes. Nowadays it is not unheard of for women to have multiple c-sections. Their genes are not being culled from the system. I have a cousin whose whose wife could not conceive normally, but had two children with gynecological assistance, another cousin who bore a child with in vitro, and a sister in law with her own congenital problems who was advised pregnancy would be difficult to achieve and dangerous to undergo. She had two children, both with congenital issue, one of who may be mentally retarded and never walk. I would never have argued on eugenic grounds that they should not have pursued children, but from an impartial biological perspective, the evolutionary implications are clear. μηδείς (talk) 20:10, 9 April 2015 (UTC)
Impartial is the key here. The issue is that the question (and many questions like this, historically speaking) place a normative value on concepts like "natural" or events which would occur without human intervention; except human intelligence is an evolutionary adaptation, and anything human intelligence produces is likewise an evolutionary adaptation which in turn feeds into the genetic distributions in real ways. To say or imply that human action is somehow against "natural" processes like this implies that evolution has an intelligent purpose or ends, and that human action stands in the way of those ends. Certainly, medicine has measurable effects on the human genome. That is an undeniable, self-evident fact. To then place normative values on those effects isn't valid, from a purely scientific standpoint. Whether one wants to make moral arguments one way or the other is fine, but such arguments cannot be based on any scientific meaning of "good" or "bad", and one will have to look for their moral code independent of the science here. --Jayron3220:20, 9 April 2015 (UTC)
I'll assume that was a response to me. I am all for medical advances. I'd likely have died in early childhood without modern medicine, and would with 100% certainty have before my 33rd birthday without extreme measures unavailable in the 70's. But civilizations falter and fall, and there will be a great culling with something as simple as the failure of the electric grid. That's fact, not moralizing. μηδείς (talk) 04:44, 10 April 2015 (UTC)
Engineering and design - constructional systems of the USSR
Are engineering and design - constructional systems of the USSR, including the civil and military army systems of the USSR being promising advanced (perfected) systems? I saw, many people told that engineering and design - constructional systems of the USSR, including the civil and military army systems of the USSR are not being perfected, because the USSR had not a advanced (perfected) computer.--85.141.239.195 (talk) 15:25, 7 April 2015 (UTC)
Every one of those words is English, and yet I can't understand what you say. Perhaps if you asked the question at the Misplaced Pages of your native language, you could be better understood? Just about every Misplaced Pages of any size has a place like the reference desk. If you tell us your native language, we can direct you better to a place where you can be understood by those trying to help you. --Jayron3216:39, 7 April 2015 (UTC)
The USSR was losing in the Cold (nuclear) War, because the USSR had not a basis of applied programming. I’m sorry, but I had not got an education in applied programming, what’s why I was asking this question.--83.237.197.142 (talk) 18:19, 7 April 2015 (UTC)
Thanks. I suppose that to become a winner in Cold (nuclear) War always must be had scientific skills, but not a finances or political reasons as biography of politics.--83.237.197.142 (talk) 18:53, 7 April 2015 (UTC)
I should edit, that I’m understood that Cold War was win the program linguistics of assembler, but what kind of symbiosis of assembler program linguistics did win, I’m don’t know.--83.237.197.142 (talk) 19:37, 7 April 2015 (UTC)
Nothing is ever perfected, I'd say; there are always compromises – between different requirements, or with the time available for the engineers to complete their task. The USSR had good computers, I believe, but they might not have been available to engineers on low-priority projects. —Tamfang (talk) 22:39, 7 April 2015 (UTC)
I wish to edit that, as I'm know, the USSR always been used the most simplest program linguistics of low levels program math languages.--85.141.232.244 (talk) 12:48, 8 April 2015 (UTC)
I was said to this, that the USSR had not got a complex mathematicals, because the USSR always been used the most simplest program linguistics of low levels program math languages. Of course, the USSR had not got a perfected control systems, because the mathematics of the USSR always been simplest.--83.237.203.56 (talk) 19:15, 8 April 2015 (UTC)
The USSR always had got a simplest mathematics which was free from applying new science methods, so the USSR always been used simplest math Basic and math Fortran.--83.237.203.56 (talk) 20:38, 8 April 2015 (UTC)
I can sort of see the point in talking like that, but the way you reply to yourself to end your sections doesn't do anything for anyone, on any level. Scale it down or go home. InedibleHulk(talk) 20:48, April 8, 2015 (UTC)
Thanks. I understood your massage attention, but I wish to say that the position of mathematics is always been the same for position of linguistics.--83.237.202.245 (talk) 21:58, 8 April 2015 (UTC)
I’m very sorry for myself replying discussion, but I must to said, that using low levels program math languages makes do it impossible to do complex calculations in mathematics and other sciences, because the math logic of this program linguistics is very (basically) simplest, that’s why the USSR had not got to do complex calculations and perfected computer. That's why always win a symbiosis program languages.--83.237.218.62 (talk) 08:51, 9 April 2015 (UTC)
Unless there is someone with a literal gun to your head forcing you to type on Misplaced Pages, you do not "must to said" anything. Your replies are going nowhere and you are not asking any questions nor listening to any answers or responses. --OuroborosCobra (talk) 10:48, 9 April 2015 (UTC)
I would like to know something more about a series of big, flat loudspeakers manufactured by YamahaMatsushita some twenty years ago. They were blue with a black frame and marketed as "digital" (whatever they mean with that word). Designed mainly for theatres and similar places.--Carnby (talk) 16:58, 7 April 2015 (UTC)
Thank you, I also discovered that they weren't made by Yamaha. The were manufactured by Matsushita and sold as Technics AFP series. I found this page with some techncal specs, but it's all in Japanese.--Carnby (talk) 11:56, 8 April 2015 (UTC)
I tried to translate Japanese text; they seem to be big-sized conventional speakers rather than magnetostatic or electrostatic ones.--Carnby (talk) 22:27, 8 April 2015 (UTC)
Squeezing a very round head inside an oval helmet?
Is it safe to squeeze a very round head inside an oval helmet? Given an oval helmet on a very round head, will that protect the round-headed bicyclist from accidents? 140.254.136.149 (talk) 17:19, 7 April 2015 (UTC)
We have a pretty long article on Bicycle_helmets. I'm not sure what you are asking. There are a few different shapes and styles, but many of them are indeed just and oval shell that rides on top of the head. A good fit is important for a helmet to properly protect, see e.g. here . There shouldn't be any squeezing of heads required to wear a helmet. SemanticMantis (talk) 17:59, 7 April 2015 (UTC)
Some cyclists wear skateboard helmets like these , to give better protection to the sides of the head. But they are hotter and heavier, so each rider makes their own choices. Here are a few scientific studies on the effectiveness of using bicycle helmets to prevent injuries in crashes . From the first article " Risk of head injury in helmeted vs unhelmeted cyclists adjusted for age and motor vehicle involvement indicate a protective effect of 69% to 74%" -- short answer: helmets do help protect against head injuries. SemanticMantis (talk) 18:02, 7 April 2015 (UTC)
There was a recent ESPN Outside the Lines about hockey helmets and such. Helmets largely protect against skull fracture. They are much less reliable for protecting against concussions. ←Baseball Bugscarrots→ 18:22, 7 April 2015 (UTC)
Please be aware that for a cyclist that knows what they are doing, and is just commuting and not racing, a helmet is completely unnecessary (cf the Netherlands and Denmark), and will only put people of cycling. 82.21.7.184 (talk) 20:19, 7 April 2015 (UTC)
Yes, the Danish and the Dutch have it great, with their protected cycle superhighways, , and all sorts of other cycling-friendly infrastructure. In the USA however, cyclists " face a higher risk of crash-related injury and deaths than occupants of motor vehicles do" . WP:OR: Last weekend I saw a car intentionally knock down some cyclists in TX. Even in non-race situations, skilled cyclists can crash and get severely injured. I would probably not wear a helmet if I cycled in the Netherlands :) SemanticMantis (talk) 20:51, 7 April 2015 (UTC)
Nope, have cycled in the very aggressive British traffic for all my life, had several crashes, never worn a helmet, and never had any head injury (or any other major injury for that matter). As long as you know how to cycle and how to fall, there's no need for a helmet at all. Most cyclists are far too meek, they need to be far more aggressive to be safe. 82.21.7.184 (talk) 07:21, 8 April 2015 (UTC)
Citation needed. Also, it would be good if you could refrain from personal attacks on the cycling abilities of posters. I agree with the poster above, cycle helmets are entirely pointless if the cyclist knows what they're doing. 131.251.254.154 (talk) 13:45, 8 April 2015 (UTC)
Everyone who is still alive has been "lucky so far". The question is whether the benefits of wearing a cycle helmet outweigh the disadvantages, and there is little, if any, evidence that they do. See here for example. AndrewWTaylor (talk) 13:23, 8 April 2015 (UTC)
Purely original research, but the VW Golf that overtook me, pulled in front and then performed an emergency stop, ended up with a helmet-shaped dent in his boot. I suspect that I wouldn't be writing this had it been head-shaped. Alansplodge (talk) 18:37, 8 April 2015 (UTC)
The IPs here have provided no references. This is not a forum. It should be obvious that in any operation of a vehicle, there are factors outside the operator's control. Even a perfectly trained and well-behaved cyclist can get hit by a drunk driver . So, do what you want, IP users, we can't give you medical advice, or require you to wear a helmet. But please do not fill this space with un-scourced claims that helmets are useless or unnecessary. Note that in the USA, many states require the use of helmets under some conditions SemanticMantis (talk) 15:53, 8 April 2015 (UTC)
The vast majority of car-bike accidents are through ignorance or stupidity of the cyclist and are very much avoidable. For the tiny minority of the rest, meh, karma. I'd rather actually be comfortable and safe on my bike than to obsessively worry and thus be unsafe. 82.21.7.184 (talk) 16:19, 8 April 2015 (UTC)
Um... - until I see evidence to the contrary, your claim is just your own opinion, and not very helpful on a reference desk. SemanticMantis (talk) 19:46, 8 April 2015 (UTC)
Well, let's get some facts straight here shall we, rather than slagging off 'some IPs', just because they are right. 1) Helmets offer some protection in certain crashes, but their effectiveness has been grossly overstated, mostly for commercial purposes. 2) The more skilled a cyclist is, the safer they are. 3) The best way to avoid head injuries is to avoid crashes and accidents altogether 4) The vast majority of accidents are avoidable by the cyclists, through assertive cycling, assuming all drivers are out to kill them (not that far from the truth), and making sure both you and your bike are up to scratch. 5) Some accidents are unavoidable, and some of those will be fatal. Deal with it. An asteroid could hit you in the head tomorrow. Now, having said that, I still maintain that making cyclists 'special' by making them wear helmets, high-vis, lycra and more such nonsense creates an illusion that cycling is weird and not normal, therefore creating a us-vs-them mentality on the roads and decreasing safety. Disclaimer: I grew up in the Netherlands, and have since emigrated and have been cycling British roads for many years now. Fgf10 (talk) 16:28, 8 April 2015 (UTC)
Fairly sure the risk of unavoidable accidents to even the most skilled cyclist is a few orders magnitudes higher than the risk of being hit in the head by an asteroid tomorrow. Anyway let's not forget the OP's question was whether a helmet would offer protection if their head was too round. The question of whether helments offer protection at all is relevant. The question of how much protection is relevant. While technically not relevant, we can perhaps accept some minor diversion in to whether or not the OP would be better served by improving their cycling skills, whether or not they choose to wear a helmet, but that would seem to be about the limit and even that seems to have a fair chance of being irrelevant to the OP. The question of whether or not mandatory helmet laws exists, or should exist, or do more harm than good, or whatever is not relevant. The question of whether the OP is worrying too much about something which is too low risk is not relevant. I'm not sure what the IP meant above about karma, but whether they meant when someone is injured or killed in an unavoidable accident they shouldn't bemoan it because they obviously did bad in their life, of whether they meant perhaps the person who injured or killed the cyclist will hopefully receive payback some time (which doesn't actually help the injured or dead cyclist, and also ignores the possibility that no one is really at fault in an accident) is most definitely not relevant. People are entitled to their person views about whether or not it's wearing a helmet is a good idea (and all the other stuff), but the RD, and in particular this question is not the place for them. Nil Einne (talk) 17:05, 8 April 2015 (UTC)
I'm not "slagging" anyone, and I don't care if they are IPs or registered like you. I mean to imply that assertions here should be supported by references. You also have provided no references to support your claims. I'd be happy to read any references you have, especially that support points 1) and 4). I'm not unsympathetic to your points, in fact I agree with many of them. Indeed, I don't wear a helmet often, even though I cycle every day in a big city. However, I still believe helmets are useful at preventing injury, and that I am taking a calculated and informed risk. Really, we should just ban all non-commercial autos, and then we'd all be much safer :) SemanticMantis (talk) 19:44, 8 April 2015 (UTC)
I think you mean "massage therapy". There is a type of vocational school called "massage therapy school", where people come out as licensed/certified massage therapists. Legal massage therapists abide by the laws of the jurisdiction, which may or may not charge illegal services like erotic massages and prostitution. You may be interested in seeking a massage therapy school in your district. 140.254.136.149 (talk) 17:48, 7 April 2015 (UTC)
A century ago, how was it decided that one had discovered an asteroid? For example, when 284 Amalia was discovered, how did the discoverer know that it wasn't just another asteroid that had already been discovered by someone else? I understand that astronomical tables have been developed for planets and bigger objects, with precise orbits calculated and future locations accurately predicted, but was this routinely done for minor asteroids? Nyttend (talk) 17:59, 7 April 2015 (UTC)
The short answer is that yes they did plot the orbits of all the asteroids. The somewhat longer answer is that sometimes asteroids did get lost and rediscovered later. See: Lost asteroids. In general, if you know the orbit, you can calculate where something would have been in the past and then match early observations with modern ones, so sometimes people do rediscover previously lost asteroids. Dragons flight (talk) 18:08, 7 April 2015 (UTC)
Also, an orbit is characterized by its orbital elements. These are just a set of numbers and are easily compared to confirm that two bodies are in different orbits, provided that there's enough data for the orbital elements to be well established. (Different computations of the orbit for the same body may not produce exactly identical numbers, due to things like perturbations and minor observational errors, but the elements will be close enough to suggest when further investigation is required. That'd be the only case where you'd actually have to compute where the thing was at some particular time.) --65.95.176.148 (talk) 18:38, 7 April 2015 (UTC)
You can probably find the original paper on the topic, this search for Auguste_Charlois between the years of 1888 and 1905 gets plenty of hits. The articles are even freely available. But they do seem to be in French... This address titled "Asteroids past present and future" may also shed some light. SemanticMantis (talk) 18:16, 7 April 2015 (UTC)
Who realised that whales and dolphins are not fish?
It is sort of obvious, when you consider pre-scuba people typically only saw whales coming up for air. Fish don't do that. The first time they killed one and realized it was filled with blubber would've also been a hint. InedibleHulk(talk) 18:49, April 7, 2015 (UTC)
Aristotle had it right, but not necessarily for the right reasons. Moby Dick contains a long passage on the subject, and concludes that dolphins must be fish. Here is what you should read: When Whales Became Mammals: The Scientific Journey of Cetaceans From Fish to Mammals in the History of Science -- it is a nice historical overview of cetacean taxonomy from a historical perspective: it starts with Aristotle, and continues through antiquity, Renaissance, and up to the modern day, detailing each new them in taxonomy and some of the morphological work that supports the claims. SemanticMantis (talk) 20:10, 7 April 2015 (UTC)
Amusingly, Misplaced Pages has an entire article on the cetology of Moby-Dick. Ishmael/Melville wasn't saying anything about cetacean biology when he said they ought to be fish. He was merely complaining about the over-narrow modern definition of "fish". -- BenRG (talk) 23:05, 7 April 2015 (UTC)
It seems obvious now, but not so much before animal anatomy became widely studied and known. In addition to needing to come up to breathe, whales and other marine mammals have flat tail "fins", which are really highly adapted feet. ←Baseball Bugscarrots→ 12:37, 8 April 2015 (UTC)
And their babies stick around nursing for about a year, depending on the species. Some kids drink 500 litres a day. Hard to imagine an early hunter cutting up a mother and not noticing that much milk, even if they'd missed the suckler. They wouldn't have called it a mammal yet, but must've thought it more cow than fish. InedibleHulk(talk) 19:19, April 8, 2015 (UTC)
Can a human body cell creates toxin by itself, or it must be done by bacteria and other foreign things? by the way, CO2 can be called "toxin"? Thanks. 5.28.178.16 (talk) 18:37, 7 April 2015 (UTC)
The human body produces many toxic waste products through natural metabolic processes. These need to be filtered out by the kidneys and then excreted. When the kidneys are not functioning properly, there can be serious health problems that result. Deli nk (talk) 18:41, 7 April 2015 (UTC)
"Methanol (wood alcohol), for instance, is oxidized to formaldehyde and then to the poisonous formic acid in the liver by alcohol dehydrogenase and formaldehyde dehydrogenase enzymes, respectively; accumulation of formic acid can lead to blindness or death." (See Alcohol#Toxicity). StuRat (talk) 18:57, 7 April 2015 (UTC)
For a simple example, see creatinine. This is produced in muscle cells and has to be excreted from the body. It is a very common toxin to be checked to see if the liver and kidneys are functioning well because the rate of creatinine production is fairly consistent throughout the day. 209.149.113.89 (talk) 18:56, 7 April 2015 (UTC)
I'm afraid it's Jay's lack of knowledge that's showing. If you consult the OED, you will find four citations of the word "toxin" being used, all of them in genuine scientific writing. (They are all from the period 1890–1905; that part of the dictionary was originally written in 1913 and hasn't been fully updated yet.) Jay is right that the word is often used in pseudo-scientific marketing, but it isn't by any means exclusive to that.
Having said that, the OED's definition of "toxin" is "A specific poison, usually of an albuminous nature, esp. one produced by a microbe, which causes a particular disease when present in the system of a human or animal body", and clearly CO2 does not fit either the "usually" or the "especially" part. But it is a "specific poison" in sufficient concentrations. --65.95.176.148 (talk) 09:56, 8 April 2015 (UTC)
See etymological fallacy; that the word was once used in a scientific context doesn't mean that is how it is being used. It would have perhaps been better to say that it has been hijacked by charlatans. It has become a shiboleth for the scientifically illiterate, and as such, even if it once had a legitimately scientific reason, has become marked and isn't used much in that way anymore. --Jayron3212:37, 8 April 2015 (UTC)
I arrive a bit late here but I'll just mention rhabdomyolysis as an example. There are of course many toxic metabolites of exogenous substances, which may vary according to genetics (there was a spectacular case of a patient a decade or two ago who dosed himself with huge amounts of DMSO and converted it to DMSOO/dimethyl sulfone and sickened the emergency personnel...) Wnt (talk) 00:57, 11 April 2015 (UTC)
April 8
Material for heaviest bat possible
If I wanted to make the heaviest and most sturdy bat/club possible, what material or element should I use? (Even if it's not easily workable, though hopefully not too radioactive). CesarFelipe (talk) 02:52, 8 April 2015 (UTC)
Short answer, heavy doesdoes not equal sturdy, so you would have to specify which you want. Others will be along with longer answers. ―Mandruss☎03:00, 8 April 2015 (UTC)
Well, by "heaviest" I mean densest, and by "sturdiest" I mean "resistant to damage/breaking, i.e. not brittle". I've looked up a few materials that are very dense yet brittle, so I don't know if they would work for making a functional bat or not. CesarFelipe (talk) 03:07, 8 April 2015 (UTC)
Yeah, dense doesn't equal sturdy, either, so you still need to specify which you want. You can't be both densest and sturdiest in the same material. ―Mandruss☎03:14, 8 April 2015 (UTC)
Anything that's really dense probably wouldn't make a functional bat, because you'd barely be able to lift it. Platinum is pretty dense and not brittle. An MLB-sized bat made out of it would be around 32 kg (and cost over a million dollars). Mr.Z-man03:40, 8 April 2015 (UTC)
The usual solution to this dilemma is to make the end heavy, but the shaft lighter (as in a mace (club)). Thus you can get a bat with a lot of inertia, yet still light enough to lift. A standard baseball bat is also tapered to get the same effect. StuRat (talk) 06:17, 8 April 2015 (UTC)
If you are looking for a combination of heavy and strong, you are probably looking for the answer "tungsten".
If you read this by use (an object to be swung to hit something), then "heavy" refers to energy stored in the bat that may be transferred to what it is being hit. Heavy normally refers to the force pulling down on something by gravity, but in this case, it refers to the force being transmitted. That makes me think of tractor trailers. Lateral force is important there. If you are carting around crates of uranium, it isn't a big deal. It just takes more gas to get moving and a longer braking distance to stop. If you are carting around eggs, you have a problem. The liquid makes them harder to move. Similarly, driving a milk truck is hard because the liquid sloshes around. So, imagine a liquid-filled bat. When you strike the ball, the casing of the bat will want to bounce back from the collision. However, the liquid will continue pushing forward. This will create a very heavy feel to the bat. Can this be done? Yes. I already did it in a school experiment years ago with a water-filled wiffle ball bat. We tried water, cooking oil, and spray foam. Cooking oil felt the heaviest when hitting a ball (and we went through a lot of bats and had a large mess because plastic casing is not very effective). I believe that mercury will be the best liquid for this usage. It is very heavy and remains liquid at room temperature. Is there a heavier naturally occurring liquid? I don't know. Next, the casing. Plastic won't work. Wood won't work. You need something that won't dent, won't crack, won't break... I'd begin with a carbon-fiber casing. How about kevlar? I have feeling that will dent. So, I'm stuck on this point. This is where the sturdiness comes in. Once you are swinging a massively heavy mercury filled bat, what kind of case won't dent or crack? 209.149.113.89 (talk) 12:08, 8 April 2015 (UTC)
Too much sturdiness could work against you. If you see a super-slow-mo of a batter making solid contact, you will see the bat flex slightly. Bats made of ash or hickory are hard but can flex. ←Baseball Bugscarrots→ 12:35, 8 April 2015 (UTC)
Indeed, what you want is efficient energy transfer, there are lots of factors that go into that, not just heaviness and sturdiness. --Jayron3212:48, 8 April 2015 (UTC)
Okay... so what material would I want for a bat to hit the hardest and not break or dent? Let's just assume that my strength is not a concern, and neither is cost. It's hard to tell if tungsten would work because certain configurations are sometimes stronger and sometimes brittle. Depleted uranium would sound good if it weren't for the fact that it's still 60% radioactive. Platinum also sounds interesting but again I can't tell whether it's durable enough for a bat because it's not regularly used for making heavy objects (unlike tungsten and uranium which are used for heavy ammunitions). Are there other alloys that would work better? CesarFelipe (talk) 15:47, 8 April 2015 (UTC)
A bat with a titanium skin and a core of U-238, osmium, or lead would make sense. Osmium is the densest naturally-occurring element, but it is toxic, and hugely expensive. The lead core would be the cheapest and safest. But I think you'd have to see baseball players becoming over-muscled weightlifters, a huge spike in injuries to batters, and a few deaths a season due to flying bats. μηδείς (talk) 18:11, 8 April 2015 (UTC)
You are assuming that the questioner wants to hit a ball with the bat. He hasn't explained what he wants to do. A bat used to punch a hole in a brick wall is much different than a bat used to hit a baseball. What if he wants to hit a ping-pong ball? Again, a very different bat. If you make the heaviest bat possible and it does nothing more than crush and flatten the baseball, that is pointless if the question is actually about hitting a baseball as far as possible. 209.149.113.89 (talk) 18:28, 8 April 2015 (UTC)
Speculative ref desk questions; a dime a dozen. "You are assuming that the questioner wants to hit a ball with the bat"; priceless. μηδείς (talk) 00:28, 9 April 2015 (UTC)
Well, if I have to be specific, let's say I want to use the bat as a blunt weapon, so I would want it to be able to hit different kinds of surfaces with force, not just a spot as small as a ball. (And again, let's assume strength and cost are not an issue). CesarFelipe (talk) 19:34, 8 April 2015 (UTC)
If you're looking for density, you can't beat Quark-gluon plasma ;). On a serious note, I think Tungsten could be a contender. I know you say "price is not a factor" but all things considered, it's only slightly less dense than platinum (19.25 g/cm3 vs 21.09g/cm3) but it's relatively common and cheap, one site I found shows 99.9% tungsten bars cost about $50 per kg, platinum costs over $1000 an ounce. Vespine (talk) 23:09, 8 April 2015 (UTC)
Since there is sexual selection in both genders, I wonder why handicap principle, or maybe rather the sources that are used in that article, gave no examples(that I noticed anyway) of animals from the female sex advertising their fitness through "costly signalling," although certainly signalling exists, whether costly or not. Now buttocks are a sexual signal. But there have been recent articles in the popular media that for some women that have prominent buttocks, it's not only buttock size, but spinal curvature. But spinal curvature seems more definitely costly than buttock size, so it seems that it could be a genuine example, although the popular media doesn't spell that out. The other possibility that comes to mind is large breasts, which can lead to back pain. Of course, one could argue that almost every signal has a cost, but the wikipedia article says it has to be a large enough cost to prove fitness.2601:7:6580:5E3:BD26:AB2F:7045:3132 (talk) 14:48, 8 April 2015 (UTC)
It's hard to spot a question in there, but I suggest if you want to debate the content of our article, posting at Talk:Handicap principle would be your best option. Of course, if you just want a debate, then you'll need to find another website. --Dweller (talk) 15:13, 8 April 2015 (UTC)
Hmm, it should be easy for someone like you to spot a question in there, even without a question mark. I would denote your reply as intentionally not to the point. Here's a question for you-you describe yourself as former bigshot on a wikipedia board, so do you miss the joy of stifling discussion?2601:7:6580:5E3:944E:5E28:28FE:2E0 (talk) 18:57, 8 April 2015 (UTC)
A term that biologists use is female ornamentation. Here is a list of recent scientific articles on the topic . As for your claims: buttocks may indeed be a sexual signal (for both human males and females), but they also serve many other purposes. Have a look at an image search for say the 100m dash - those muscles help us run. If you look at a google scholar search for /costly signaling human/ , you'll see that almost all the scientific work is about cultural signaling, not morphological signaling. SemanticMantis (talk) 15:42, 8 April 2015 (UTC)
I was under the impression that what you're really seeing is larger hips - which correlates directly with the ability to successfully give birth - which would be an obvious indicator of reproductive success what will be selected for. It's easy to imagine spinal curvature being a part of that too. SteveBaker (talk) 17:27, 8 April 2015 (UTC)
It's called sexual selection. Men who mated with unhealthy females who consumed their fat reserves and had small behinds would be less likely to conceive, and more likey to loose a child due to malnutrition. Hence a gene that makes men prefer curvaceous women would make sense, even if otherwise, large behinds might be a handicap in running to escape a predator. That prerence would result in women's buttocks becoming larger, as the larger the butt, the more eager suitor and healthy babies. μηδείς (talk) 00:18, 9 April 2015 (UTC)
There have been some amusing and interesting reports on this in the press lately ( but trying to chase down any real research out of them is a bit frustrating. I ought to look harder but I'm having a hard time picturing what kind of study would actually have been done to get a convincing proof. Still, any excuse is a good excuse :) Wnt (talk) 19:19, 11 April 2015 (UTC)
calorific value of carbon monoxide
I am performing an experiment that needs the calorific value of gases produced from combustion of 1kg of coconut shell.I tried to google it but could
not find any useful detail.Atleast ,a simplistic approach to estimate the required value is cordially welcome.115.241.9.191 (talk) 17:06, 8 April 2015 (UTC)
I don't know what coconut shell is made of precisely, or why it would produce carbon monoxide during combustion, but maybe Standard enthalpy of formation is helpful. From the table in that article one can see that the energy of 1 mol CO is 110.5 kJ lower than the combined energy of1 mol of elementary carbon and 1 mol of elementary oxygen (i.e. 0.5 moles of O2), meaning that converting these into 1 mol CO will produce 110.5 kJ in heat. - Lindert (talk) 17:19, 8 April 2015 (UTC)
And just to be clear, that is the heat produced by converting 1 mol of CO into CO2, according to CO + 1/22 -> CO2, so it's the difference between the standard enthalpies of CO and CO2. - Lindert (talk) 18:26, 8 April 2015 (UTC)
Misplaced Pages has an article titled Orgasm which has links to further articles that will help you in your research. Feel free to read that article, and follow links from there and see where it leads you. --Jayron3223:55, 8 April 2015 (UTC)
Per that article, pretty much the same. A bit longer for the ladies, generally, and more of a comedown for the gentlemen. InedibleHulk(talk) 00:00, April 9, 2015 (UTC)
We have no current way of directly measuring qualia, subjective conscious experience. Consider, how do we know that what I see and name as red is not experienced by another person as what I would name green? The color spaces in our heads might be flipped, so that white is black and blue is yellow. As long as we agree to call the same things by the same names, consistently, there would be no way to know that our subjective experiences were reversed.
We do know that people with color blindness have a different experience fro that of trichromats, but only because we notice that the words we use conflict, or the distinction is lost on the dichromat. Even then, we don't know if dichromats view both red and green as red, or as green, or as violet, for that matter.
Assumptions based on physiology say that since the neurotransmitters are the same, the experience must be similar, but we have no idea at what level of processing qualia arise; molecular, cellular or at the level of one or more parts of the brain.
We do know that gene therapy for color blindness has worked in animals, but it has not yet been tried in humans. We will learn a lot if they report that everything appeared red, or green, or brown before, but now I still see red, but I also see a new color, the one people were always calling green. μηδείς (talk) 00:12, 9 April 2015 (UTC)
An AC circuit contains a 0.01 microfarad capacitor and 0.06 micro farad capacitor that are connected in series. What is the total capacitance of this circuit — Preceding unsigned comment added by 64.56.106.62 (talk) 12:47, 9 April 2015 (UTC)
That is only true if they are in parallel. For capacitors in series you'd have to be talking about the inverse of capacitance for that to be right. Dmcq (talk) 20:57, 10 April 2015 (UTC)
I did not understand, did a binary calculation system machines been a prototypes of computer – the machines of program binary codes?--85.141.232.245 (talk) 15:22, 9 April 2015 (UTC)
So, it to become me to avow that the USSR did not invented a program language and computer, I’m suppose that the USSR had got to invented a binary calculation system machine which was been one of much from word, of course it did been electromechanical (radiotechnical) and electronical versions, but not microelectronical version, so the USSR did it more simplest than over members, because the economy of the USSR was been progressing for win. I don’t know, how binary calculation system was been relating with binary programming?--83.237.200.102 (talk) 17:30, 9 April 2015 (UTC)
The Enigma machine was not a prototype of the computer as we now use the word. As for your other comments, you may find it useful to learn the term popovism. Finally, you are strongly encouraged to ask questions in the Misplaced Pages of your native language. (If you have already tried that, and they have sent you here, you are encouraged to take your questions to another Misplaced Pages that may be able to understand you.) RomanSpa (talk) 18:09, 9 April 2015 (UTC)
In Russian language: В чем состоит логическая посылка – что-то является частью чего-то, то есть что в ней общие а что частное, вычисления или программирование?--83.237.205.199 (talk) 22:03, 9 April 2015 (UTC)
Yes. Most programming includes some calculation, but I have written programs with no calculation; conversely, most programming involves actions that are not calculation, such as deciding (according to empirical conditions) what to do next. —Tamfang (talk) 18:30, 11 April 2015 (UTC)
Enigma wasn't by any stretch a "computer". The meaning of the word "computer" has changed quite a bit over the years - back in the second world war, a "computer" would be a person who was employed to do arithmetic calculations...later, the term "mechanical computer" came to mean "a machine that can do what a human computer can do" - which is to say, basic arithmetic. But these days, we don't generally consider a simple four-function pocket calculator to be "a computer" (although it might easily contain one). The more modern definition would be something that's Turing machine equivalent...which requires that it's able to take decisions and execute loops. That said, I don't think Enigma came remotely close to making any of those definitions.
What Enigma basically did was to have a bunch of disks with electrical contacts around the outside and a bunch of wires that connected every contact to a different contact. A stack of those wheels produced a scrambling of wires leading from the keyboard switches to a set of lights. Every time you pressed a key, the wheels would turn, re-wire the keys to a different set of lights and light up whichever light happened to be connected to the key you pressed. A machine like that can't do even simple addition or subtraction - so it's not a computer by any reasonable definition.
The simplest mechanical computer I know of is the Digi-Comp I (I own one of these - the second photo in the article is mine). It effectively has just two bits of memory...yet is (arguably) a horribly limited turing machine - and therefore should properly be called a "computer".
Stop engaging him. Stop answering him. He's a troll. Steve, you put a fair amount of effort into writing that post; I assure you it is entirely wasted. This IP will likely write a response completely ignoring everything you wrote, possibly making some off the wall philosophical declaration that either has nothing to do with this topic or still declared Enigma to be a computer, and the USSR to not have some language something or other. It isn't worth it. --OuroborosCobra (talk) 11:36, 10 April 2015 (UTC)
Of course the USSR was made it's own choice for electronical versions of technics, but not microelectronical versions of technics, because it is been necessary for win, so because in electronical versions it been made the much more microtransistors on square decimeter of perimeter on electronical matrix, than on microelectronical matrix, that’s why the USSR had not got a microelectronical versions (technology) of technics, it may been only composite versions of technics.--83.237.192.41 (talk) 12:39, 10 April 2015 (UTC)
Of course the USSR had not do a complex calculations, because the USSR did not used the program languages or always been used a low levels program languages, so that's the microelectronical technology did not need to the USSR.--83.237.218.251 (talk) 14:50, 10 April 2015 (UTC)
It did’s all been depended on by technology, but of course the most simplest program languages are always been much faster that over program languages, if technology it did’s been could.--83.237.218.251 (talk) 16:28, 10 April 2015 (UTC)
In Russian language: Проблема состоит в том, что простейшие языки программирования всегда строятся на примитивной математике (на примитивном логическом уровне).--83.237.198.209 (talk) 17:42, 10 April 2015 (UTC)
Thanks. I’m should thinking that the calculation versions of computer and programming versions of computer are been two different versions of computers.--83.237.218.251 (talk) 16:28, 10 April 2015 (UTC)
Russian Misplaced Pages can answer your questions in Russian at This link Please use them, as your poor English language skills makes it almost impossible for us to help you. --Jayron3217:18, 10 April 2015 (UTC)
So, you've been blocked at Russian Misplaced Pages, and came here to cause problems? Right. Thanks. --Jayron3218:11, 10 April 2015 (UTC)
The Polish use is been not serious!
I see no problems in my membership in Wiki, because at first I’m did not answering for medical advanced problems, so I’m did not done the medical problems at all, and at second I’m did not discovered the secrets which nations law been defended.--83.237.198.209 (talk) 18:58, 10 April 2015 (UTC)
You are not a 'member' of anything. And your endless spamming of our reference desks with frequently incomprehensible questions followed by even more frequently incomprehensible commentary on any responses is a gross abuse of our facilities. That you haven't as yet been banned from posting has much more to do with internal Misplaced Pages disputes than it has with your postings themselves - and sooner or later, we are going to send you packing, since you are clearly under the delusion that this is some sort of combined forum and exercise in forensic linguistics. Though frankly I see little reason to believe that your convoluted grammar etc is actual evidence of poor English - it looks to me to be intentionally worded for maximum confusion. I suggest you find another location for your trolling, before you are obliged to. AndyTheGrump (talk) 19:15, 10 April 2015 (UTC)
I see no laws problems in I'm did. As I’m know, the nations laws always been defended from break and theft new ideas, but not from asking and taking idea.--83.237.198.209 (talk) 19:19, 10 April 2015 (UTC)
Thank you for confirming that you are a troll - nobody who understood even the most rudimentary English would ignore my last post, unless they were intent on continuing this façade... AndyTheGrump (talk) 19:48, 10 April 2015 (UTC)
I have a vented immersion heater connected to a 90 gallon water tank in the loft. The tank supplies 0.5 bar of water pressure. There is a vent pipe from the immersion heater that allows any expansion of water to release safely outside. Obviously if I connected the immersion heater directly to the 3 bar mains water supply the water would overflow out of the vent pipe continuously.
However, could I hypothetically replace the loft tank with a pressure reducing valve set to 0.5 bar and connected directly to the mains? From the perspective of the immersion heater it would still receiving 0.5 bar of water pressure, so it shouldn't make any difference as far as I can see. Am I correct in that assumption or have I missed something vital?
Yes, your talking about what is referred to as a unvented hot water system. However, you will also need some other bits -- all explained here: --Aspro (talk) 18:46, 9 April 2015 (UTC)
No that's not right at all.
It would still be a vented system and work at low pressure, the only thing that would change is that the low pressure 0.5 bar of supply water to it comes via a "pressure reducing valve" instead of a loft head tank. If too much pressure builds up inside the immersion heater it would still overflow out the vent pipe.
Unvented systems are entirely different and typically deal with high pressure. I'm not asking about converting a vented system into an unvented system (which is not possible without replacing the entire immersion heater and boiler system) I am asking about changing only the method of water supply to a vented system while keeping everything else the same.
Generic answers won't help here because the system I am proposing is a complete bodge and probably doesn't even have a name. It's an exercise in inventive thinking. Pressure reducing valve (talk) 19:28, 9 April 2015 (UTC)
OK lets go back to basics. I'm assuming your immersion heater is upstairs (two story typical home) and 'immediately' above that you have loft with the tank. Your presuming that tank deliver water at 0.5 bar. Highly unlikely. Reason: measure the hight from the immersion heater top to the loft tank overflow. Divide that distance in feet by two and it will give the approx pressure in PSI. A pressure of 0.5 bar will raise water some 7½ feet – probably above your loft tanks over flow level. Resulting in all your hot water flowing into the garden (or where ever its vented). One would need an adjustable pressure relief valve to ensure this did not happen. Does that make more sense?--Aspro (talk) 20:24, 9 April 2015 (UTC)
Perhaps I've over-complicated the question and need to boil it down to something more basic. The immersion heater expects 0.5 bar of water pressure from a loft head tank. Any more than 0.5 bar will cause the water to escape out of the vent. We don't want this to happen. Can the loft head tank be replaced by something else that supplies water at 0.5 bar pressure without water escaping out the vent pipe, or is there something special about the way loft head tanks work that can't be replicated by simply replacing the head tank with a 0.5 bar water supply? Pressure reducing valve (talk) 19:43, 9 April 2015 (UTC)
Using a pressure reducing valve (set correctly) would have the same result as the tank only if the flow rate was the same as well.
I don't think you understand the difference between pressure and flow rate. Whatever the flow rate (unless it is zero) if the pressure is more than 0.5 bar the vent will overflow. A lower flow rate just means it will overflow slower. Is there anyone on here who can give an actual answer instead of just making vague and inaccurate guesses? Pressure reducing valve (talk) 23:20, 9 April 2015 (UTC)
@ Pressure reducing valve. Understand pressure head and then you will realize that the 0.5 bar figure is not applicable outside a very tight conditions in this situation. You are asking a form of complex question]that rests on a questionable assumption. I.E. the 0.5 bar pressure head. We do are best to answer reasonable questions here. If you don't like the replies to your complex question then take it else where and waste somebodies else time but stop wasting ours.--Aspro (talk) 14:14, 10 April 2015 (UTC)
If you don't have an answer to the question then don't post. And especially don't post disparaging comments about "wasting peoples time". You are acting like you've gone above and beyond in trying to help when in fact all you did was post PDF file that wasn't relevant and then claimed the conditions of the question are too" tight" for you to answer. Well then, don't answer it! You are free to not "waste" your time by refraining from posting and let someone else answer, and I'd be very grateful if you did. Pressure reducing valve (talk) 19:32, 10 April 2015 (UTC)
@Pressure reducing valve: Replacing the cistern this way shouldn't be a problem. In practical terms: Assuming that the actual inlet pressure provided from the cistern is 0.5 bar at rest, you'll have the same pressure at the hot water outlet if on the same level or a minor difference if not. When you install a pressure valve to put away with the cistern, you need to compensate for fluctuations in pressure due to heat expansion, spikes when turning water on and off and finally fluctuations from the valve itself. With a cistern you have a "preset max. high pressure" which is at the highest fill level. Pressure valves might not be as precise at this critical point so setting the valve's pressure slightly lower and/or raising the vent pipe should do. Hope that helps.--TMCk (talk) 21:00, 10 April 2015 (UTC)
What information is needed to calculate storage volume of a reservoir. I have inflow, outflow and a value for 2s/dt-Q but I don't know what dt is so this is useless. I also have a value for max capacity of river downstream and my guess is this is what I need to use. I also have a storm hydrograph but as I'm only considering baseflow storage volume, I've ignored this. But now I'm not sure what to do. 90.201.190.183 (talk) 18:55, 9 April 2015 (UTC)
Building our own water-mill or hydro power station are we? Think you'll find that dt just means Δ T or in other words the difference in temperature in kelvins or centigrade. The density (mass per cubic volume) changes with temperature.--Aspro (talk) 19:08, 9 April 2015 (UTC)
I should think the expansion of the water due to temperature is small enough that it could be ignored (and it's not linear, anyway, so would require a look-up table to calculate accurately). Just taking the initial volume of water, then adding in the elapsed time since then, multiplied by the net flow (inflow-outflow) would seem to get the job done:
Vcurrent = Vinitial + (Vin - Vout)t
If that volume is less than zero, then the reservoir is empty (except for the small amount currently flowing through it). If that volume exceeds the max capacity, then the reservoir will be at max capacity (possibly with the surrounding area flooded). Evaporation (and precipitation directly into the reservoir) might be significant on an open reservoir, however, and that depends on not only temperature, but also humidity, wind, and sunlight. As a practical matter, you might just add fudge factors to Vin and Vout, which would vary by season, to account for precipitation and evaporation.
Also, if not obvious, using a formula to predict the future volume of the water in the reservoir makes sense, but if you want to know the current volume, just go a measure it. (I suppose this could get complicated, though, if the reservoir isn't a simple shape.) Without taking current measurements and updating Vinitial to match, your end calculation will get farther and farther off, the larger t gets, due to inaccuracies in Vin and Vout. StuRat (talk) 19:18, 9 April 2015 (UTC)
What is need is either (a) a topographic map of the reservoir, including areas that are currently under water, or (b) a detailed history of inflow, outflow, direct rainfall, and surface elevation, encompassing the full range of depths that the reservoir supports. In practice you probably need a map, because it is very difficult to compute the amount of water added when it rains directly on the reservoir. Looie496 (talk) 14:26, 10 April 2015 (UTC)
Radio question 1
WLW, Cincinnati, holds the record for the strongest ordinary US radio broadcast, at 500,000 watts for several years during the Depression. As noted by our article, it's well recorded that people living near the transmitter could hear broadcasts coming out of non-radio metal objects (fenceposts, mattress box springs, etc.), and there were even reports of people hearing the broadcast out of their metal tooth fillings. Fast forward to the present, and we have reports of electromagnetic hypersensitivity, which are generally discounted. Would radio-in-teeth be considered a form of electromagnetic hypersensitivity (and thus the stories would be considered mistaken folklore), or is electromagnetic hypersensitivity pretty much completely unrelated to the disturbances that would quite understandably result if your teeth started playing music? Nyttend (talk) 21:40, 9 April 2015 (UTC)
It's completely different. Radio playing from metal fillings, though I'm not sure if it's actually even been reliably recorded, is well within the laws of physics. The purported electromagnetic hypersisitivy on the other hand, has no basis in physics or biology, the energy levels of the average exposure are far too low to cause the sorts of physiological changes reported, tissue being far less affected by radio waves than metals. As stated in our excellent article, 'sufferers' can't even distinguish a placebo field from a real field. Psychosomatic disorders is where you want to be looking for them.... Fgf10 (talk) 00:28, 10 April 2015 (UTC)
Lucille Ball claimed that she picked up radio signals through her fillings. Our article says: Ball revealed in this interview that the strangest thing to ever happen to her was after she had some dental work completed and having lead fillings put in her teeth, she started hearing radio stations in her head. She explained that going home one night from the studio, as she passed one area, she heard what she thought was morse code or a "tapping". She stated that "as I backed up it got stronger. The next morning, I reported it to the authorities and upon investigation, they found a Japanese radio transmitter that had been buried and was actively transmitting codes back to the Japanese." - but these claims are really pretty preposterous and Snopes were unable to find confirming evidence. SteveBaker (talk) 05:54, 10 April 2015 (UTC)
You may be interested in this similar question I asked a while back . Steve also brought up Lucille Ball at that time :) I did learn about Magnetostriction, which still seems relevant to this question. SemanticMantis (talk) 14:50, 10 April 2015 (UTC)
I think we should leave the much beloved Lucille Ball out of this because there is some history to that account that makes the account questionable but for all the right reasons. So I will leave that there. Back (before solid state diodes and mosfet detectors) – Radio Hams that didn't get their earthing sorted out properly found they where getting RF burn to their lips from the microphone. Their lead-amalgam fillings (as where popular in the day) also tingled. Whether this diode in the teeth actually demodulated AM to the point were they could 'hear' the broadcast like on the radio is debatable. I am going back 30- 40 plus years here but the impression I got is that they could only sense low fidelity music. Speech was unintelligible unless they had the gobs stuck up close against the mike an were sensing their own speech whilst transmitting. So Lucille Ball (or her entourage) would have been familiar with this commonly reported phenomena and used it, to deflect the political pressure she found herself under, by conjuring up this anecdote.. As to mattresses picking up RF, it was determined in the last few decades that the reason why so many people reported hearing sounds of a meteor despite it be in 60 to 40 miles up was that many conductive materials around them acted as half wave antenna to the low frequency radio wave generated and vibrated thus producing an audible sound.--Aspro (talk) 14:58, 10 April 2015 (UTC)
We had a metal coffee table frame that picked up a radio station. I also had a radio that picked up CB broadcasts, even when turned off. So, it's not all that rare to pick up radio frequency signals on devices not intended for that purpose (or frequency). But it seems less likely that any part of the human body could act as an antenna (other than implants, like fillings). StuRat (talk) 02:01, 11 April 2015 (UTC)
Radio question 2
While reading on the above subject, I found this chat thread. I was amused by the idea from anomalous_cowherd's comment: I suppose it would work to use a super-powerful radio broadcast to charge batteries, but if you did that, would it have a discernable effect on local radio transmission, enough that neighbors would notice and engineers would be able to find you? I understand that the guy's batteries would be absorbing the signals, not reflecting them, but isn't that also the case for anyone using a normal radio receiver? Nyttend (talk) 21:40, 9 April 2015 (UTC)
It's a matter of degree. To make a significant dent in his electric bill he'd have to absorb on the order of a kilowatt. I can't find information on how much power is absorbed by a typical AM/FM radio, but I think it must be a tiny fraction of a watt.
Since the total radiated power of that transmitter is only ~1 MW, it's hard to believe that he could collect enough to be worth the trouble. And since the wavelengths are 250m and up, and his garage was presumably much smaller, it wouldn't cast a sharp shadow and I don't see how it could cause problems for anyone else. So I doubt the story is true, but I'm not very sure about my reasoning. -- BenRG (talk) 04:04, 10 April 2015 (UTC)
Crystal radio sets can be completely powered by the radio signal...I made one as a kid that was able to extract sufficient energy to drive an earpiece without a battery. Clearly it was extracting energy from the radio signal - so we can say with certainty that you can quite easily extract at least some energy from the signal alone. If you subtract energy from the signal by receiving it, then that has to attenuate the signal for people further from the transmitter. However, it's going to be a very, very tiny attenuation. SteveBaker (talk) 05:45, 10 April 2015 (UTC)
Correct, the power absorbed by a typical consumer AM/FM radio would be measured on the order of magnitude of millionths or billionths of a watt, or less. For example, see Signal strength, which lists some realistic electric field values at common distances from an ordinary AM or FM transmitter. You can convert from electric field strength (in units of volts per meter) into voltage by multiplying by antenna length; you can convert from voltage to received power by computing V/R, and for lack of any better value of R, you can assume an antenna whose input impedance is perfectly matched to the impedance of free space (377 Ω). This is all sloppy back-of-the-envelope kinds of math: of course, if the answer matters, you should perform more sophisticated calculations and make less flimsy assumptions. You might want to pick up an advanced textbook on radio engineering (and what better one than Fred Terman's Radio Engineer's Handbook!? It's quite old, but it's got a very practical and pragmatic approach to calculating such quantities, although Terman still uses archaic nomenclature like "kcps" instead of kHz, and all his circuit examples are based on tubes that haven't been readily available for decades). Short summary: a real AM/FM radio is extracting very little power. Steve correctly points out that this is enough to power a crystal radio's earpiece - but not its amplifier - and as I recall, when I built an unamplified crystal radio, I used a massive antenna - the water pipe attached to the shower - to pick up the strongest possible signal! You can extract just enough voltage to drive a piezoelectric speaker, and hear sound, but it's quite faint unless you add a powered amplifier.
Radio enthusiasts might also read our article, dBm, a normalized logarithmic unit of true received radio power that radio engineers use. A WiFi base station might transmit at +20 dBm and the computer receiver might pick up +0 dBm. A common AM/FM or shortwave receiver may work around -75 dBm. People who work with spaceships - satellite television radio engineers ("SATCOM") and research scientists - commonly work in the world of -100 and -120 dBm. Keep in mind that these are logarithmic scales, and that the gain-bandwidth product (which is a material property, and is the same for any radio built out of common CMOS semiconductor materials) essentially dictates your total power/bandwidth/noise!
Not that I am aware of off the top of my head. Even hormones that we link to more specific gender functions, such as testosterone and estrogen, are present in both genders and useful in both. I don't know of a male use for progesterone, but it is found in males, regardless. --OuroborosCobra (talk) 11:32, 10 April 2015 (UTC)
Still going to need to tell us what properties. Matter has tons of them. We can list things until the cows come home and if you don't list for us what you are looking for, you can keep telling us we haven't found it. --OuroborosCobra (talk) 11:30, 10 April 2015 (UTC)
Is there any relationship between limescale and nephrolithiasis or bladder stones?
Could it be any relationship between drinking limescale (kettles) to nephrolithiasis or bladder stones? What does happen in person's bodies when they drink water with limescale? 149.78.253.71 (talk) 09:06, 10 April 2015 (UTC)
That's a combo of minerals, but I believe at least some of them bind with fats in the small intestine, and then pass normally from the body in the feces. StuRat (talk) 02:10, 11 April 2015 (UTC)
Higher atmosphere= More homogenized Earth?
Hi there,
If the Earth had had larger atmosphere,
Would it have been more homogenized on its climate? Exx8 (talk) 09:39, 10 April 2015 (UTC)
Maybe, maybe not. This kind of counterfactual question is hard to address- what else would be different to make this change? Mass of the Earth, power of the sun, etc etc. Anyway, Jupiter has a lot of atmosphere, and it's not very homogenous, same for Saturn, see Atmosphere of Jupiter, which details all kinds of atmospheric dynamics. I suspect you're thinking that more atmosphere would sort of give more room for mixing, and hence even things out, but that's not the way it works. I suppose someone could set up a General_Circulation_Model and increase the amount of atmosphere to see what happens, but I couldn't find any published work along those lines. SemanticMantis (talk) 17:19, 10 April 2015 (UTC)
Is it possible for somebody to become pregnant through anal sex if she has a rectovaginal fistula? I hate to ask this, but I couldn’t find information on this. --66.190.99.112 (talk) 12:38, 10 April 2015 (UTC)
By definition it's possible, but what someone is doing having anal or vaginal sex when they have such a fistula is the bigger concern, as is the need to see a specialist and a as surgeon immediately. μηδείς (talk) 16:18, 10 April 2015 (UTC)
See Heart#Structure. While it does not itemize it into a neat little list, you can easily extract the various kinds of tissues in the heart, and from there figure it out for yourself. --Jayron3216:23, 10 April 2015 (UTC)
Actually questions of this sort are always very tricky, because there is no clear definition of what constitutes a single "type" of cell. An additional factor is that there is ambiguity about exactly what belongs to the heart. Obviously the muscle cells, but what about the walls of the blood vessels that run through it, or the nerve ganglia that lie on its surface? Looie496 (talk) 18:08, 10 April 2015 (UTC)
Can someone please help me with this? I don't understand what this is asking.
Describe in detail what you know about the enthalpy, entropy, and free energy changes when a sample of gas condenses to a liquid. How does temperature affect these changes? 108.33.159.120 (talk) 17:34, 10 April 2015 (UTC)
You are forum shopping. You were advised at the Teahouse that this appeared to be a homework question, and that we do not answer homework questions. You were told that if you had more specific questions, you could ask them at the Reference Desk. This is the original question, not a more specific question. Robert McClenon (talk) 17:39, 10 April 2015 (UTC)
I'm sorry, thats not what I was trying to do. I understand that this is a homework question. I'll be more specific. Is free energy the same as spontaneous? Please don't be angry with me. 108.33.159.120 (talk) 17:42, 10 April 2015 (UTC)
No, it's OK. You were redirected here, and this is the correct place to ask. However, as I explained in the last location you asked, you might want to start telling us how YOU would answer the question, and see if we can confirm your answer or critique it in some way. What the question is asking is to explain the changes in certain thermodynamic quantities when a substance changes from a gas to a liquid. So, as say steam condenses to liquid water, the values of enthalpy and entropy and free energy all change. What the question wants to know is how those values change. And it also wants to know what the role of temperature plays in it as well. Does that help at all? --Jayron3217:45, 10 April 2015 (UTC)
Drag in Le Sage's theory of gravitation
One of the problems with Le Sage's theory of gravitation is that Earth will experience drag and eventually come to a halt, sink into the Sun, and be destroyed. I don't disagree, but the description of this problem isn't complete enough for me. I figure it is because my understanding of relativity must be flawed. So, this is my understanding. Please correct my ignorance... Earth is moving through space. Assume that there actually are tiny little specks of energy speeding around at the speed of light. Those coming towards the leading side of the Earth will be travelling towards the Earth at the speed of light. Those coming at the waning side of the Earth will be travelling towards the Earth at the speed of light. If the Earth doubles in speed, the relative speed of the little particles will be the same. The ones on the leading side won't be coming towards the Earth any faster. If the Earth comes to a stop, the ones on the side that was leading won't be coming any slower. They will still be coming at the speed of light. So, no matter the speed of the Earth or direction of travel, the incoming particles will always be heading towards the Earth at the speed of light. That makes drag difficult to describe. As the Earth moves along, the leading side won't be hit by more particles because that would require the particles to move towards the Earth faster. The waning side won't be hit by less particles, because that would require the particles to move towards the Earth slower. I simply don't know where I'm wrong and I know plenty of people here will gladly expose my mistakes. 209.149.113.89 (talk) 17:44, 10 April 2015 (UTC)
Energy is not a speck, it is not matter. Energy is a means to quantify change. We do have models that use particles to model the behavior of energy. But energy itself is not a substance. Energy is a property of a substance. For example, imagine we have a person named John. We can take a property of John, like say his height. When I say "John is 175 cm tall", I'm describing a property of John. But you can't carry around a bucket of height. Tallness is not a material you can hold in your hand. To speak of it this way is meaningless. It sounds silly to say "Here, we have little specks of height, and if we gather enough of these specks, we can carry them around." That's nonsense. In the same way, energy is a property of something, it is not really a substance that can be carried around or occupies a space or anything like that. --Jayron3217:55, 10 April 2015 (UTC)
I understand your point, but it doesn't address the problem. The Le Sage theory states that gravity is created by tiny particles travelling at the speed of light, slamming into everything. The argument against the Le Sage theory is that objects moving through a medium of these particles will experience drag because the objects will hit more particles in front and less from behind. But, that assumes that as the objects move, oncoming particles will relatively speed up while tailing particles will relatively slow down. 209.149.113.89 (talk) 18:51, 10 April 2015 (UTC)
If you are moving towards a particle source you will encounter more particles per unit time than if you are moving away from it. That's true because the particles have to catch up with you, even if they are moving at the speed of light. Dragons flight (talk) 19:47, 10 April 2015 (UTC)
If the tiny particles are moving at the speed of light, they are not matter. Because matter cannot be accelerated to the speed of light. Now, light itself does create drag (see Radiation pressure) because of the relativistic mass of light, as noted in our article, the drag caused by light has to be taken into account in long-distance space travel, for example. So, the effect is real. I have no idea what this means for the Le Sage theory. You may want to read up on gravitons, which are a hypothetical gauge boson, the gravity equivalent of the photon. Still, since photons create drag, and we haven't crashed into the sun because of them, I'm not sure why gravitons would do that either... --Jayron3221:01, 10 April 2015 (UTC)
It's worth noting that at the time of Le Sage, the speed of light was understood as just a very fast speed, and not an absolute limit. At the time there would have been no problem imagining moving faster than that or that relative motions were additive in the normal way. Dragons flight (talk) 22:24, 10 April 2015 (UTC)
My problem is not discounting Le Sage's theory. My problem is Feynman's reasoning. He said that these "particles" (assuming that they did exist) would cause drag. I couldn't see how something travelling at the speed of light could cause drag. In my mind, you start with "If you are travelling at 99% the speed of light and turn on your headlights, how fast will the light travel as it comes out of your headlights?" Reverse that. "If light is hitting the front of your car and you speed up to 99% the speed of light, how fast will the light hitting your car be travelling?" However, it was noted above that photons do create drag. I fully understand the effect of drag at the speed humans travel. In my mind, I'm having trouble distinguishing between the absolute speed of these imaginary particles (which is supposed to be the speed of light) and relative speed if you are moving towards or away from them. 75.139.70.50 (talk) 00:11, 11 April 2015 (UTC)
This "drag" is an inherent consequence of the assumptions Le Sage sets up. He assumes the existence of some particle which can carry and transfer momentum. He demonstrates that this momentum transfer would look like an inverse-square law of attraction - similar to the force of gravity - but only solved for the normal direction of incidence. If you solve the very same equation for all directions of incidence - and this is something we can now do because we have the methods of calculus that were barely understood in 1690 - then you find that the momentum transfer has to imply a shear force that we do not observe. If you want the complete answer, we'll have to go through a gorey mathematical treatment - this is the sort of thing that might honestly take a solid hour of physics-equation-solving at a university-level. Anyone who can correctly waltz through 60 minutes of physics equations usually charges money for the skill! Furthermore, unless you take a very advanced "history of wrong physics" course, you'd be wasting your time to re-disprove every historical mathematical inaccuracy that was ever forwarded! It takes a lot of effort to rigorously prove wrongness; few professors will waste an entire precious lecture to work the details out; fewer would publish their notes to the internet at large. ... Anyway, if you'd really like to read Feynman's run-down, CalTech hosts an archive of his entire gravity lectures. These chapter notes would typically be spread over several days of university-level classwork. Take some time to digest them. And remember! These are the easy lectures - physics for first-year, mostly-non-major students. There is almost no math in his treatment! Nimur (talk) 15:36, 11 April 2015 (UTC)
Suppose you are traveling at speed v. After time t, you will have moved distance vt. In the forward direction, you will have encountered all photons within a distance equal to the sum of the distance you traveled plus the distance the photons traveled, . In the reverse direction, any photons within a distance equal to the distance photons traveled minus the distance you traveled will have caught up, . Assuming equal illumination in both direction, the force you feel will be proportional to . Hence the drag. Dragons flight (talk) 01:29, 11 April 2015 (UTC)
This sure sounds a lot like the virtual particle explanation of the Casimir effect - a model for which I admit a similar disdain, as the interaction of real fluctuations of the positions of particles within the plates makes far more sense to me than the ability of virtual particles to measure the conductivity of plates at the nodes where they are never present. But one thing about the virtual particles in that explanation (or any explanation involving virtual particles) is that there have to be infinitely many of them, in "every possible frame of reference", i.e. at 0.99c there is just an infinite a sea of virtual particles going faster than that as going slower. The same was not available to Le Sage because, well, there was only so much people would believe in the 1600s! (Correct me if I'm wrong) Wnt (talk) 19:06, 11 April 2015 (UTC)
Earthquakes
Am I correct in thinking that the most damaging earthquakes have small ground accelerations, medium ground velocities and high ground displacements? — Preceding unsigned comment added by 94.14.146.60 (talk) 18:09, 10 April 2015 (UTC)
Fatalaties and damage are influenced by magnitude, but also by location.A vertical up and down movement is less like to cause as much damage to buildings than a horizontal side to side movement. It is the horizontal movement that walls (of buildings) are least resistant to. So a small horizontal movement may effect more damage than a larger up and down movement.--Aspro (talk) 18:37, 10 April 2015 (UTC)
S-wave is the type that oscillates perpendicular to the direction of propagation, P-waves are the compression waves that move in the direction of propagation. Seismic wave details these, as well as the several type of surface waves. Surface waves generally do more damage than the body waves, which are used to locate epicenters and time of the event. Here are a few refs that discuss the types of waves and how they affect structures , and they also have better illustrations than our articles. As for actual damage from historical earthquakes, that depends a lot on where it happened, and what types of structures were there. The same earthquake in the middle of Siberia might cause very little damage, compared to if it occurred in NYC. So most damaging is often a matter of where the quake occurred, not what its seismic features are. Here are some lists of most damaging/deadly earthquakes, not the large variation in physical attributes: . From Lists_of_earthquakes, we have this nice figure, which shows that fatalities and damage are only loosely related to magnitude. SemanticMantis (talk) 19:24, 10 April 2015 (UTC)
I try to see and to understand the Lord God Wishes, as we all knowing well the states of the Asia in the majority are the states of red socialistic camp.--83.237.221.202 (talk) 20:09, 10 April 2015 (UTC)
Why do (most) tree frogs have horizontally slit eyes? Wouldn't vertical slits be an advantage when you're jumping or when you're catching a fly with your tongue to be able to accurately gauge the distance? This confirms that it's indeed the EYE-riss, but that doesn't give more help. — Sebastian01:31, 11 April 2015 (UTC)
If the frog is on the surface of water, would vertical slits potentially result in confusing imagery when seeing both above and below the water line? ←Baseball Bugscarrots→ 02:06, 11 April 2015 (UTC)
Thank you, that was very helpful. The jov article's wording "better image quality for contours perpendicular to the pupil’s long axis" is something I implicitly took for granted in the above; it's good that they're making it explicit.
I hadn't thought of the pupil article. That contained at some point what seems like a good answer, written by DrChrissy: "Horizontal slit pupils are more effective in the vertical plane and allow better detection and recognition of obstacles or predators as they move into sight at speed." It got subsequently changed by someone who apparently misunderstood DrChrissy's wording, so I now reworded it. It contains admittedly some original research, but the situation seems pretty obvious to me. But I'm not married to my wording; I won't fuss if someone deletes it. — Sebastian07:40, 11 April 2015 (UTC)
Hi Sebastian. Just a friendly note. Your discussion about specific changes should probably go on the article Talk page (and maybe copied here - I don't know, I am new to this pasge). I like your edit, but you should try really hard to find a source for it - I suspect it's half-life will not be long otherwise! All the best.__DrChrissy (talk) 11:18, 11 April 2015 (UTC)
When the heart is enlarged is called cardiomegaly, but what is the opposite of this case called? (when the heart is reduced). Thanks 149.78.253.71 (talk) 01:47, 11 April 2015 (UTC)
Well, microcephaly means an abnormally small skull. I'm not sure why the "micro" is a prefix instead of a suffix, or how it would be applied to "cardio". StuRat (talk) 01:52, 11 April 2015 (UTC)
The opposite of cardiomegaly is a normal heart. Microcardia is a totally different condition. It's like asking what is the opposite of a six-fingered hand, and answering a four-fingered hand.
I think you mean "cardiomicroly" or some such. Micromegaly means "smallbigly" and nonsensically doesn't answer the question. Cardio should be in there somewhere. And the OP's question makes sense, even if it is ultimately unanswerable because the condition doesn't actually exist. There's nothing hypothetically wrong with supposing that a condition of heart shrinkage is possible. --Jayron3204:13, 11 April 2015 (UTC)
GIven that at least some cardiomegaly is the result of left ventricular hypertrophy, there's a sense in which one might consider hypoplastic left heart syndrome its opposite... "Microcardia" is an abnormally small heart, but despite there being a word for it, is like a unicorn in not being spotted or referred to often. - Nunh-huh05:00, 11 April 2015 (UTC)
According what I know, the opposite of large is just small. Anyway, the main question is how small heart called in medical terminology (as a large heart is called cardiomegaly)149.78.253.71 (talk) 09:08, 11 April 2015 (UTC)
You are confusing logical contraries with contradictories. The opposite of white is not black; it is "not white". One isn't cured of high blood sugar by low blood sugar. Normal blood sugar is not high. But it's also not low. See square of opposites. μηδείς (talk) 18:47, 11 April 2015 (UTC)
Injecting a substance into the veins with the tongue.
I was wondering if there are any studies on any indigenous peoples or intravenous drug users that inject substances into the veins by biting than using their mouth and tongue as a sort of injection needle. Are some substances best delivered at the temperature of the human body? Bullets and Bracelets (talk) 04:55, 11 April 2015 (UTC)
Would be difficult to effectively administer drugs that way. Blood pressure is always higher than air pressure, so merely opening a vein with something like the teeth then applying drugs topically is an unreliable way to deliver the drugs the blood stream. Intravenous needles rely on using a syringe to apply higher pressures to ensure the drug is delivered to the blood stream efficiently. If blood is rushing out of a punctured vessel, then positive pressure prevents the drug from entering the body. At best you'd get the drug into the blood via simple diffusion, which is such an inefficient process for this purpose it doesn't sound like it would be a useful way to do things. All that being said, I wouldn't preclude individual anecdotes of people trying the method you describe, and even being successful (for an arbitrary definition of success), however there's no reason to suppose that it is a widely successful method, or statistically significant. --Jayron3205:04, 11 April 2015 (UTC)
No. If the person didn't bleed out from the ruptured blood vessel, he'd die from sepsis. Please stop asking absurd questions prefaced by I was wondering if there are any studies, such as "Are there any studies as to what happens if you extract an embryo and inject it into someones blood stream?" You'll end up being blocked for disruption. μηδείς (talk) 05:11, 11 April 2015 (UTC)
William S. Burroughs described an ad hoc method involving a pin and an eye dropper, where the hole would first be made and external pressure used. So I don't see any obvious reason why this would necessarily fail, though opening the vein with teeth is sure hell a stretch. (but tooth sharpening, hey you never know in biology, or anthropology for that matter) Sepsis from introduced bacteria is of course possible, but primitive people survive a lot of abuse (in part because they tend to die so young...) But the ancients often found ways to do things topically; for instance, if you go back and look at Dioscorides you'll see that opium was a topically administered drug much of the time. So I don't think trying to get foreign substances into a vein would have been high on their to do list. Wnt (talk) 18:57, 11 April 2015 (UTC)
Hi there,
Few questions:
1st: if atoms absorb only the exact photons that contain the exact amount of energy to leap the energy levels of the atoms, doesn't it mean that the possibility of absorption should be negligible? I mean, if 2 atoms have different energy levels, the likelihood that the photons that are emitted from one atom to another will be in the exact amount of energy is nothing. Is it? And even if you are able to emit all the wavelength that atoms can absorb, still, the length of the line that should be at the Spectroscopy should be invisible (Because its width will be nano-metric). And yet, we do see it with our naked eye.
2nd: Why in molecular Spectroscopy the absorption isn't binary? I mean, molecules can absorb some of the photons of a given wavelength, in contrast to atoms for example.Exx8 (talk) 08:48, 11 April 2015 (UTC)
our eyes are actually pretty sensitive, even to narrow line width absorptions. In addition, there Ade many factors that broaden those line widths, such as Doppler effect and motion of atoms making them "experience" a different wavelength, or broadening from atomic collisions (this broadening can be enough to turn gas discharge lamps from line sources into continuous sources). Molecular spectroscopy is subject to similar line broadening effects, with so!e additional ones, such as solvent effects. --OuroborosCobra (talk) 10:43, 11 April 2015 (UTC)
As OuroborosCobra points out, the atoms will be in different states and then you need to take into account the doppler effect, but that doesn't solve the problem that you raised, as each atom in its own rest frame will have precisely defined energy levels.
The problem is resolved by considering that the precise energy levels only arise when you ignore the coupling of the atoms to the electromagnetic field. In that hypothetical case, electrons in excited states would never make a transition to the ground state and emit radiation, but they would have precisely defined energies. What happens in reality is that these excited states are unstable due to the coupling to the electromagnetic field. Electrons in such states then do not have precisely defined energies (only so-called stationary states that do not evolve in time can have precisely defined energies, this is related to the time-energy uncertainty relation, you can also compare this to the fact that the frequency of a signal is only well defined if it is exactly periodic for an an infinite duration). This means that atoms can both emit and absorb photons with energies that differ from the differences in the energies of the energy levels. The probability density for such a process depends on the energy difference between the energy of the photon and the energy difference between the energy levels between which the transition takes place. The longer the lifetime of an excited state the more precisely defined the energy level is which then leads to a narrower peaked probability distribution for the photon energy. Count Iblis (talk) 16:17, 11 April 2015 (UTC)
Space: digital or analog?
Given a surface, can you place an object at any point that you want? Or would space be a kind of chessboard, when you can put the piece at any square, but not between two? Intuitively, it makes sense to believe that the first scenario is the case, but how can something like this be tested? At some time, by really small distances, we won't be to measure the space coordinates anymore, since we might have reached the maximum precision of our measuring devices. — Preceding unsigned comment added by 83.50.111.54 (talk • contribs)
It's an open question that gets attention in the popular press. Look for the word granularity in our article quantum gravity. μηδείς (talk) 19:40, 11 April 2015 (UTC) In the future, please sign your posts by adding four ~~~~ at the end. μηδείς (talk) 19:40, 11 April 2015 (UTC)
. In the reverse direction, any photons within a distance equal to the distance photons traveled minus the distance you traveled will have caught up, 
. Assuming equal illumination in both direction, the force you feel will be proportional to 
. Hence the drag. 
Resolved
