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August 16

Relativity and Bernoulli[edit]

If I were moving in a car with the window open, and released a piece of paper very close to the open window, which way would the paper move? --Σ talkcontribs 00:54, 16 August 2011 (UTC)[reply]

I don't think relativity is relevant at the speed most of us drive, and I've never seen anything released from a car window move in any direction other than backwards, except when there was a forwards wind of greater velocity than that of the car. How can Bernoulli change this? Dbfirs 01:27, 16 August 2011 (UTC)[reply]
Augh, I could've clarified (as I always seem to be unable to do). If I were moving in a car with the window open, and released a piece of paper very close to the open window, would the paper fly outside or stay in the car? Bernoulli states that a fluid moving at high speeds has a lower pressure (or something along those lines), so if I were in the car watching, the paper should fly out, as relatively, the air outside the car is moving faster. But if an observer outside the car were watching the experiment occur, relative to him, the air in the car should be the faster fluid, and the paper should stay in the car. Does the paper leave the car or stay in it? --Σ talkcontribs 01:34, 16 August 2011 (UTC)[reply]
The only thing that matters is the speed of the air on either side of the paper; it has nothing to do with who is observing it. Both the person inside the car and outside the car would note that the speed of the paper is essentially moving the same speed as the air inside of the car, and that the air outside of the car is moving faster than the paper. Bernoilli's principle is about the air speed relative to the two sides of a surface; both observers will arrive at the same result for that relationship. --Jayron32 01:40, 16 August 2011 (UTC)[reply]
In my experience, airflows around an open car window are somewhat turbulent, but there tends to be a dominant current of air forcing itself into the car (generally towards the rear of the window), and another forcing itself back out again (generally towards the front of the window). So the short answer is that it will depend whereabouts in the plane of the window you let go of the paper. It'll either fly backwards inside the car, as Dbfirs suggested, or else it will be sucked out. As also noted, relativity has nothing whatsoever to do with it. --Tagishsimon (talk) 01:47, 16 August 2011 (UTC)[reply]
I depends on the wind speed and direction relative to the car, the speed of the car, the contour of the car. The contour of the car determines the aerodynamics. Close to the car, a pressure differencial exists pushing the piece of paper outward by a certain amount. The piece of paper has a high surface area to weight ratio, so is majorly affected by air resistance. This means that relative to the ground, both the car and piece of paper will continue forward, although the piece of paper will have a high deceleration, and move outward from the car. Relative to the car, the piece of paper will be moving back, out and down. A wind speed and direction, complicates this. Plasmic Physics (talk) 02:18, 16 August 2011 (UTC)[reply]
Although special relativity certainly isn't useful in this problem, I think the OP might be referring to Galilean relativity, which does have some pertinence here. Red Act (talk) 03:01, 16 August 2011 (UTC)[reply]
Yes, apologies for misunderstanding the question (it was the early hours of the morning here). I've observed all of the behaviours described above, and turbulent airflow makes it very difficult to predict which one will actually happen at any particular position, but the probability of the paper initially moving outwards increases as you adjust the starting position further from the stationary air (relative to the paper) in the car. To achieve the opposite effect with greater probability, one would need to throw the paper backwards so that it was stationary relative to the outside air, then the faster airflow would be (on average) inside the car. As mentioned above, turbulence makes the actual behaviour very complicated and almost impossible to predict without a very complex computer model. If the paper initially moves out, it very quickly decelerates to approximately the speed of the outside air, then the moving air inside the car can draw it in again because the inside pressure is then lower relative to the paper, by Bernoulli's principle. Has anyone ever recorded the behaviour on a high-speed video camera? It would be interesting to see it in slow-motion. Dbfirs 06:40, 16 August 2011 (UTC)[reply]

Strength of Immune System for healthy adult from 2010 versus 1810[edit]

Have the medical / hygiene advances made in the last 200 years led to relatively weaker immune systems for modern humans? Would a healthy Londoner from 1810 have a better IDS than his 2010 counterpart? If we sent the 2010 Londoner back to 1810 in our theoretical time machine, would he be in greater peril than if we brought our 1810 guy forward? I'd put my money on the 1810 guy simply because he's healthy is a much worse environment, but he would lack vaccinations... are there scientists who study this sort of "historical immunodefense development"? The Masked Booby (talk) 02:57, 16 August 2011 (UTC)[reply]

But we today are descended from people who survived the Spanish flu and polio epidemics of the 20th century. It's not an obvious call. HiLo48 (talk) 08:05, 16 August 2011 (UTC)[reply]
@Masked: I'd put my money on the 1810 guy, too, but for completely different reasons. The prevalence of infectious diseases is much, much lower today than it was in urban London in 1810. Smallpox doesn't exist anymore, and polio is virtually wiped out, too. Cholera, typhys, typhoid fever, tuberculosis, and a host of other bacterial and fungal diseases which were once rampant are now a lot less common, so the transfered 1810 individual would have to deal with fewer infections than the transferred 2011 individual. Nutrition nowadays is much better than what it was for the average Londoner 200 years ago. Same with health care, which was little more than beads and rattles compared to modern medicine. The 2011 individual would be placed in a seething brew of noxious microbes with little hope of effective treatment. The only advantages he would have are the fact that he has been inoculated against some microbial diseases, and that he comes from a population which, as HiLo48 has said, represents the survivors of 200 years of epidemics and pandemics. Dominus Vobisdu (talk) 08:24, 16 August 2011 (UTC)[reply]
Note that you seriously skew the calculations when you specify a "healthy" individual from 1810. A "typical" individual from then might have already had their health damaged, and immune system compromised, by diseases such as tuberculosis, which would make them quite susceptible to recent diseases. StuRat (talk) 20:57, 16 August 2011 (UTC)[reply]
The odds are against the 1810 guy when he gets exposed to modern pathogens, unless he moves to an isolated cabin. The doorknob or railing Mr1810 touches in 2011 might have just been touched by someone who just flew in from any third world pesthole. There is far more frequent international travel now than then. Mr1810 gets on a subway car or bus, and he is breathing microscopic droplets coughed out by dozens of other people, who have travelled far and picked up myriad pathogens, in a poorly ventilated situation. Modern city dwellers and air travellers endure this microbe soup regularly, while the 1810 guy would encounter it in steerage, say, but with fewer changes of personnel. We, on the other hand, are descended from people who had some natural immunity to many diseases, as evidenced by their surviving long enough to propagate. Of course the 1810 guy might have survived or been vaccinated against smallpox, while a modern person born after the early 1960s likely would be vulnerable to smallpox, since they stopped vaccinating children against it in the 1960s in many countries. The modern person would likely be vaccinated against many killer pathogens which were deadly in 1810, such as tetanus, diptheria, and whooping cough, hepatitis, rubella, mumps, meningitis, pneumonia and polio, as well as some flu strains. A modern person might be less "hardy" in general against digestive upset from drinking water or eating food which is contaminated or slightly spoiled. Americans/Europeans vacationing in "developing countries" seem to come down with "la tourista" while locals are less affected by the pathogens. Modern children tend to be raised more antiseptically than pioneer or third world children, which might account for the lack of hardiness with respect to environmental germs. Edison (talk) 16:25, 17 August 2011 (UTC)[reply]

Compared to 1810, almost everyone living today is severely vitamin D deficient (50 nmol/l calcidiol levels are considered sufficient today, while the natural level attained by people who are outside all day long can be as high as 200 nmol/l or higher), and that has an impact on the immune system as explained here. Count Iblis (talk) 16:52, 17 August 2011 (UTC)[reply]

Heat and salty taste perception[edit]

I've noticed that French fries and other foods which have a distinct salty taste when fresh and hot lose some of that flavor when allowed to cool (more so when refrigerated than when left at room temperature). Why does this happen? 69.111.78.166 (talk) 03:28, 16 August 2011 (UTC)[reply]

Two things:
  1. Substances must be soluble to be tasted. Solubility of most solids and liquids increases with increasing temperature; as does the rate at which they dissolve, so hot foods will dissolve more readily in saliva than cold foods, speeding the rate at which your tastebuds will pick them up.
  2. Most of what people attribute to taste is actually smell; the nasal passages are connected to the mouth via the pharynx, and lots of your sense of taste is actually picked up by your olfactory sensors in your nose. Vapor pressure is directly related to temperature; so warmer substances form vapors more than colder ones do, meaning that more of the vapor will be detectable, and thus provide more intense flavors than if the food were colder. Note that while salt doesn't readily form a gas, you can "smell" salt because it does form a sort of aerosol whereby tiny particles of salt can become dispersed in the air; and this process is also temperature dependent.
Does that help? --Jayron32 04:09, 16 August 2011 (UTC)[reply]
Another thought: Perhaps salt crystals placed on the surface of things like fries tend to fall off as a result of temperature changes, due to contraction and expansion an changes in the viscosity of the oil to which it adheres. Do you see lots of salt crystals on the sides and bottom of the container ? StuRat (talk) 20:39, 16 August 2011 (UTC)[reply]

energy and matter[edit]

How can energy and matter be equivalent when matter has gravity and energy does not? --DeeperQA (talk) 03:40, 16 August 2011 (UTC)[reply]

What makes you think that energy does not exert gravitational attraction? --Jayron32 04:00, 16 August 2011 (UTC)[reply]
Oh, and just to correct something you said. Energy and matter are not equivalent. It is energy and mass which are equivalent. See Mass–energy equivalence. Mass is merely one property of matter. --Jayron32 04:01, 16 August 2011 (UTC)[reply]
(ec) It's only in Newtonian gravity that energy doesn't contribute to gravity. In general relativity, all forms of energy contribute to gravity. In more technical terms, in the Einstein field equations, all components of the stress–energy tensor contribute to the curvature of spacetime. If you view Newtonian gravity as an approximation to general relativity, by assuming that only mass contributes to gravity, one basically is assuming (among other assumptions) that only the T00 component of the stress–energy tensor is non-negligible. Red Act (talk) 04:22, 16 August 2011 (UTC)[reply]

well .........Energy has some characteristics such as transferring with waves, the dependence of particle -wave in quantum mechanics gives us best guide to solve such problem, although it is clear that kinds of energies have not gravity field ."question :when mass is converting to energy , what kind of energy will produce  ?(only nucleic?)"--Akbarmohammadzade (talk) 05:17, 18 August 2011 (UTC)[reply]

Uterine fibroids[edit]

This question has been removed. Per the reference desk guidelines, the reference desk is not an appropriate place to request medical, legal or other professional advice, including any kind of medical diagnosis, prognosis, or treatment recommendations. For such advice, please see a qualified professional. If you don't believe this is such a request, please explain what you meant to ask, either here or on the Reference Desk's talk page.
This question has been removed. Per the reference desk guidelines, the reference desk is not an appropriate place to request medical, legal or other professional advice, including any kind of medical diagnosis or prognosis, or treatment recommendations. For such advice, please see a qualified professional. If you don't believe this is such a request, please explain what you meant to ask, either here or on the Reference Desk's talk page. --~~~~
--Jayron32 04:00, 16 August 2011 (UTC)[reply]

galactic orbits[edit]

Going by the measurements of the spirals of the stars orbiting the center point of a galaxy do the orbits of the stars comply with Kepler's laws of planetary motion and if so can it be determined if the orbits are elliptical? --DeeperQA (talk) 08:48, 16 August 2011 (UTC)[reply]

See spiral galaxy. Plasmic Physics (talk) 09:21, 16 August 2011 (UTC)[reply]
Kepler's laws are strictly valid only for the two-body problem, where both bodies are point masses. A galaxy is not a point mass but has an extended mass distribution with more or less complex structure. Therefore the laws of planetary motion do not hold for stars in galaxies. In particular, the orbits are not elliptical and they are not even closed, meaning that a star does not return to the same point after one rotation. The rosetta orbit is closer to what the stars do in galaxies. Note that the one place where we can actually observe stellar orbits over full periods is at the Galactic centre and there the orbits are indeed ellipses and comply with Kepler's laws. This is strong indication that the mass in this region is dominated by a point mass, i.e. a central black hole. But this is true only at the very centre, but not in general. --Wrongfilter (talk) 09:52, 16 August 2011 (UTC)[reply]
Also see galaxy rotation curve. Gandalf61 (talk) 09:54, 16 August 2011 (UTC)[reply]

Dishwashers and salt[edit]

If I use the top of the range, all-singing all-dancing diswasher tablets, do I still need to load my dishwasher with salt?

I've never heard of loading a dishwasher with salt. Is that the custom in some places? Where? HiLo48 (talk) 10:36, 16 August 2011 (UTC)[reply]
See Dishwasher salt. Per this, you should still add salt to the separate container if you are using those combo tablets, as it is used by the machine's water softener. --Kateshortforbob talk 10:42, 16 August 2011 (UTC)[reply]
I'm still interested in where? Is this an American thing, with Americans assuming that the whole world is just like them? I'm in Australia, a high school teacher teaching kids about salinity right now. No-one in their right mind would think of adding salt to the environment here. And our dishwashers work fine. My dishes come out clean. Are you sure it's necessary? HiLo48 (talk) 10:46, 16 August 2011 (UTC)[reply]
It smells a scam to me. I know that salt, an oxidising environment, or low pH, and iron leads to corrosion. I would like to know what would happen if you would exchange low pH for high, as exists in a dishwasher. I imagine you would get similiar results, generally salt, water and iron do not mix well. Oh, I forgot to mention, the stainless steel components of the dishwasher contains iron, as do cutlery. Plasmic Physics (talk) 11:04, 16 August 2011 (UTC)[reply]
There seems to be a lot of confusion here. Dishwasher salt is used in countries or places with relatively hard water. In countries or places where the water is already soft, it isn't needed. If you bought your dishwasher locally, most likely it would be designed with whatever is the norm where you live. I believe pretty much throughout New Zealand dishwashers don't generally need dishwasher salt and there may be no compartment (although [1] says there often is but no one knows about it but [2] doesn't agree and also suggests there is occasionally hard water). Contrary to the claim above it appears some dishwasher in Australia do come with a dishwasher salt compartment [3] and it may be useful in some parts of Australia. BTW, the Dishwasher#Dishwasher salt article discusses this briefly and it is hinted at in the earlier linked dishwasher salt article so I don't really understand the need for conspiracy theories. Also the earlier link by Kateshortforbob was to an apparent UK site which even mentions the UK, so I don't understand the assumption it was an American thing after the link had already been provided. In fact the limited info I've seen so far including our own article suggests to me it may be more common in Europe. (Based on the fact a lot of the discussions etc seem to related to Europe, including the UK. Even some discussions of dishwasher salt in the US I find seem to mention it as being common in European brands of dishwashers.)
P.S. I seem to recall reading some dishwasher manual which specifically said it isn't used in Australia or NZ. I thought this might be common, one of the reasons I was surprised by some of the other replies, but rechecked mine before replying only to find it didn't feature any such discussion (and the refs also support the idea a lot of people here don't know about it). But looking at the Australian ref again I see someone says some Asko manuals do mention that (and a search finds others saying the same thing). I believe a friend had such a dishwasher and I read their manual once so it was probably there. BTW, many refs suggest using ordinary salt is a bad idea due to impurities but [4] claims salt without anticaking agents like kosher salt is okay as per a US Navy study. Also I found [5] [6] which support my conclusion it's rare in the US, and where present is mostly in European models. Since per the wikipedia link by Shantavira below, water can be quite hard in the US I'm not quite sure why. I guess either dishwasher powder formulations there are designed to be used without softening the water or they just put up with the poorer performance or houses there more commonly come with water softeners somewhere along the supply.
Nil Einne (talk) 11:54, 16 August 2011 (UTC)[reply]
Agreed, anyone with water hard enough to need dishwasher salt would be better off buying a whole home water softener, because you wouldn't want to drink or bathe with hard water, either. StuRat (talk) 20:32, 16 August 2011 (UTC)[reply]
[citation needed]? Our own article says 'The World Health Organization says that "there does not appear to be any convincing evidence that water hardness causes adverse health effects in humans."'. Also while hard water can make it more difficult to wash, according to various things I've read including [7], people who are used to using hard water often prefer the feeling of their skin after washing using hard water. (Although Water softening suggests that may be partially incomplete and that part of the reason skins feels more slippery with soft water is not just because of surface oils but remaining soap.) And 'flat' hair after washing using soft water seems a common complaint e.g. [8] [9] (although [10] doesn't agree). BTW I just noticed the dishwasher salt article says the granule size does matter (unlike the earlier ref on the US Navy although I don't know what the granule size of kosher salt normally is) and that dishwasher salt commonly has an anticaking agent (although it could be a different type) but obviously not iodide common in iodised salt. The dishwasher article suggests perhaps the problem is magnesium based anticaking agents but also suggests it doesn't contain anticaking agents at all. Nil Einne (talk) 12:03, 17 August 2011 (UTC)[reply]
I didn't claim that hard water is unhealthy. It can be quite unpleasant, though, and, if water full of iron tastes so nasty that you drink soda instead, then it is unhealthy, but only indirectly. The rust or mineral stains all around the sink and tub are also rather unpleasant. StuRat (talk) 21:28, 19 August 2011 (UTC)[reply]
Dishwasher salt is in common use in the UK - dishwashers generally have a special compartment that you pour it in to. As Kateshortforbob say, its purpose is to reactivate the water-softener - my dishwasher's heating element noticeably starts to fur up when salt is low. It doesn't cause salty dishes or corrosion. It's also pretty cheap - I live in a hard-water area and probably spend less than £5 a year on it, so it's not very promising as a potential scam. AndrewWTaylor (talk) 11:19, 16 August 2011 (UTC)[reply]
(e/c)I'm in the UK. All of the dishwashers I've owned have had separate containers for the powder/tablet, salt and rinse aid - there's also some more information about the salt in that article. I haven't conducted any experiments, but from experience, if any of these components is missing, the dishes tend not to come out as clean.--Kateshortforbob talk 11:22, 16 August 2011 (UTC)[reply]
Presumably it isn't necessary everywhere. See Hard water#Regional information.--Shantavira|feed me 11:57, 16 August 2011 (UTC)[reply]
Also supporting the idea it may be useful in parts of Australia.... Nil Einne (talk) 12:03, 16 August 2011 (UTC)[reply]

OP here - sorry I didn't sign, got disturbed by the doorbell! It's UK-specific question, and one that's been at the back of my mind for some time. --TammyMoet (talk) 12:01, 16 August 2011 (UTC)[reply]

OK, maybe it's not a scam then, but it must have disadvantages. Even without the pressence of salt, stainless steel cutlery have been known to rust in a dishwasher, albeit very gradually. Salt may catalyse this reaction. Are there any such studies done, on the negative side-effects of using salt in this way? Plasmic Physics (talk) 13:51, 16 August 2011 (UTC)[reply]
It appears that you are basing your opinion on the use of salt in soft water. In hard water, there are a lot of calcium and magnesium ions (among other hardeners). The salt becomes ionic in water (by definition) and, instead of remaining as salt, it combines with the hard ions in the water. Therefore, it removes the hard ions, softening the water. If you use too much salt, you will have the effect of saltwater. But, you'd know if you are using too little (you get calcium buildup) or too much (you get corrosion). -- kainaw™ 14:38, 16 August 2011 (UTC)[reply]
Oh yes, chloride salts of group 2 are generally more soluble than their hydroxide, carbonate, and sulfate salts; and the sodium salts produced as by-products are comparitivly more soluble also. Plasmic Physics (talk) 12:35, 17 August 2011 (UTC)[reply]

Diabetes and low blood sugar[edit]

I've seen glucose tablets among products for diabetics in pharmacies. For a long time I didn't notice the apparent contradiction—what is the use of glucose tablets to someone whose problem is high blood sugar?! I figured people with diabetes must sometimes have low blood sugar. What is the connection between diabetes and low blood sugar? --173.49.79.200 (talk) 14:08, 16 August 2011 (UTC)[reply]

A person using insulin or any of the many diabetic medications is controlling blood sugar levels through medication, not through natural insulin production. So, if a person miscalculates, there is a threat of low blood sugar. That is dangerous. Using glucose (sugar) pills counteracts low blood sugar. -- kainaw™ 14:33, 16 August 2011 (UTC)[reply]
More information here. Alansplodge (talk) 14:38, 16 August 2011 (UTC)[reply]
(ec)And a problem here is that a factor 2 below normal levels will give you quite severe symptoms, while a factor 2 above normal levels isn't a big deal. In fact, the recommendation for diabetes patients is to stay below twice the normal level. This then does lead to long term health problems. Count Iblis (talk) 14:44, 16 August 2011 (UTC)[reply]
This is a common misconception about diabetes. Hypoglycemia is, in fact, pretty common in diabetics. Because little/less insulin is produced, no 'sugar' is put away for later; hence, when the body needs to raise blood sugar levels (at the middle of the night, for example) there isn't any. I think this is more true of Type 1 diabetes than Type 2 diabetes, but I'm not sure. It has little to do with miscalculation, really; most diabetics are advised to inject (or similar if they have a pump) even if low already if they are about to eat. Grandiose (me, talk, contribs) 15:36, 16 August 2011 (UTC)[reply]
There's something inherently random about the effect insulin has. Sometimes it seems to have virtually no effect, and other times the same amount, given seemingly under identical conditions, has a huge effect. Some thoughts as to why this might be:
A) Insulin is commonly injected into fat tissue to provide for "time-release". However, how quickly it finds it's way to the blood stream is variable. The insulin pump is designed to address this problem, by delivering small doses periodically. However, they haven't yet linked this with a blood glucose test to have it only deliver as much as needed, based on current blood sugar readings, so it must still be adjusted manually.
B) Insulin is easily "spoiled". Freezing, age, sunlight, or dropping/shaking the vial can all make it ineffective. A patient might adapt their dosages accordingly, but then get a new batch of insulin and find the higher dosages they are used to now cause low blood sugar.
C) A condition known as brittle diabetes causes good insulin to seemingly randomly refuse to work, and at other times work more than it should. Perhaps there are unknown biological factors which also must be in place for insulin to work normally. StuRat (talk) 20:05, 16 August 2011 (UTC)[reply]
I am diabetic and generally have problems not exceeding 200 and will jump to 260 if I eat simple carbs like Idaho potatoes. However if I eat nothing but hard boiled eggs by the end of the day my blood sugar can drop to 120 where 130 is normal. If I do drop that low then sometimes I can start to get dizzy and have to eat potatoes to drive my blood sugar up. They work faster in my case that sucrose tablets. --DeeperQA (talk) 05:27, 17 August 2011 (UTC)[reply]
130 what is normal? Surely you are not speaking of mg/dL? 100 is "normal" for that unit of measurement. 120 is still high, per Diabetes mellitus#Diagnosis and Diabetes management, which says the goals are "Preprandial blood glucose: 4.0 to 6.0 mmol/L (72 to 108 mg/dl)], 2-hour postprandial blood glucose: 5.0 to 8.0 mmol/L (90 to 144 mg/dl)." Of course this is not medical advice, and you should do what your doctor/nurse/diabetes educator advises. Edison (talk) 16:08, 17 August 2011 (UTC)[reply]
I've found that juice works quickly, too. I always thought that sugar tablets should only be used if away from home when that's all you have. If at home you might as well have juice and get some nutrition along with the sugar. Starches, like potatoes, should provide sugar over the long run, so those might be good, too. StuRat (talk) 08:17, 17 August 2011 (UTC)[reply]
It might seem that juice is full of "nutrition" unlike glucose tablets, but a 8 oz(249mL) Motts 100% apple juice bottle says it only has 4% of the Daily Value needed of iron and 20% of the Vitamin C, besides the 29g carb. The same 29 carbs from glucose tablets (Dex 4 brand) would furnish 72.5% of the minimum value of Vitamin C. I can't get excited about the 4$ of the iron, and I take a multivitamin anyway. Edison (talk) 16:08, 17 August 2011 (UTC)[reply]
Apple juice is about the least nutritious of the juices. With a cup of orange juice, on the other hand, you get over 200% of your vitamin C and also get significant amounts of thiamin, folate, and potassium: [11]. StuRat (talk) 06:52, 18 August 2011 (UTC)[reply]

I've read that in severe cases, you need to inject people with a large amount of glucose. What sometimes happens is that someone has been using insuline to enhance physical performance, basically taking large amounts of glucose and injecting himself with a large amount of insuline so that his muscles will be able to use all that energy quickly. But if too much insuline is used relative to the glucose intake, the bloodsugar level will go very low and that will be fatal without intervention, because the huge amount of excess insuline will make it impossible for the body to recover by itself. Count Iblis (talk) 16:35, 17 August 2011 (UTC)[reply]

21 cm line of Hydrogen[edit]

I want to do a project on the application of 21 cm line of Hydrogen. What are the applications of 21 cm line of hydrogen in astrophysics??? can anybody help me ??? — Preceding unsigned comment added by Suman90kundu (talk • contribs) 14:55, 16 August 2011 (UTC)[reply]

Does the 21 cm line article help? Red Act (talk) 15:50, 16 August 2011 (UTC)[reply]
As Red Act stated, the WP article on the topic is a good starting point. The basic idea is that quantum effects means there are many more energy levels than the simple Bohr model shows. The 21 cm line is caused by electrons transitioning between energy levels subtly different, but shown as the same under more basic models. Feel free to post more specific questions when you have them. Rosilisk (talk) 15:56, 16 August 2011 (UTC)[reply]

The "Chupacabra" of DC[edit]

What could this cryptid be? (Afaik still unidentifed as of 15:27, 16 August 2011 (UTC)). "Prince Chupa" WikiDao ☯ 15:27, 16 August 2011 (UTC)[reply]

It's probably a mangy canid according to this site. WikiDao ☯ 15:34, 16 August 2011 (UTC)[reply]
It does look an awful lot like... a canid with mange. Poor thing. --Mr.98 (talk) 15:35, 16 August 2011 (UTC)[reply]
According to this report, the cryptid was captured and then its captors set it free. As usual, we are left with naught but blurry pictures; scientists will be unable to study the specimen; but it will live on in the local lore (and a suburban dumpster). Nimur (talk) 18:33, 16 August 2011 (UTC)[reply]
I saw it on the local news and thought I'd ask. I asked elsewhere and her opinion was that it is a hairless fox. It was apparently lured into the trap with just a little leftover Chinese food [12], so will probably be easy to investigate further if it is not identified more conclusively soon from the information already available. Strange and unfortunate that they (hospital workers out on a smoke break) just let it go. WikiDao ☯ 20:09, 16 August 2011 (UTC)[reply]
Poor dog. :( It's most likely to be a Xoloitzcuintle. And no, it's not mangy, it's just naturally hairless. It's a very ancient breed considered sacred by the Aztecs, Toltec, and Mayans, among others. And now it's hunted as a chupacabra, ironic really... -- Obsidi♠n Soul 23:42, 16 August 2011 (UTC)[reply]

Aircraft with rectangular wing profile[edit]

Can an aircraft with a rectangular( or any other non-aerofoil shape) wing profile fly?

That's a pretty general question. Airfoil shapes are used because they provide the best combination of lift and drag for a specific use of aircraft. Airplanes at higher speeds typically wish to have a lower Lift coefficient which ensures lower drag, while still being able to achieve enough lift due to the high speed. These wings will not resemble a 'traditional' airfoil.
Taking your question in the most basic manner as possible, any flat shape can help something 'fly' - just think of a paper airplane. The paper is roughly rectangular, and certainly doesn't have an airfoil shape.
Also, you can sign your name by putting four '~', which will show: Rosilisk (talk) 18:30, 16 August 2011 (UTC)[reply]
(EC) You can have wings in a non-traditional airfoil shape. The advantage that the traditional airfoils have is they have a good lift to drag ratio. You could have an airplane with sheets of plywood as the wings, and as long as the plywood was properly angled, the plane could fly, but the amount of drag it would create would be such that you will waste a lot more fuel, and need a stronger power plant then you would for a proper airfoil. For some interesting shapes, you can check out the article on Kline Fogleman airfoils. Googlemeister (talk) 18:33, 16 August 2011 (UTC)[reply]
I call shenanigans on the Kline Fogelman airfoil. Have a look at this diagram of laminar flow from the article: pure pseudoscience. I can draw streamlines in any shape I want, but that doesn't mean the air actually flows this way. Was this diagram based on experimental observation? Was it based on a well-respected CAD / CFD simulation? Or was it just drawn any which way the artist thought looked nice?
It seems that all independent verification has invalidated the claims that a Kline Fogelman airfoil does anything; there is a reason that most airfoils have a smooth surface. In conventional aviation, we use flaps to intentionally change the lift/drag characteristics. At best, we can say that the airfoils drawn in the Kline-Fogelman article are in a state of "perpetual flaps-extended" mode. Nimur (talk) 18:50, 16 August 2011 (UTC)[reply]
Kline Fogelman airfoils are used only on small scale RC aircraft where the requirements are different then on full size. Thus KF airfoils are only used at low speed and with ground effects, both conditions which are more forgiving for a non-smooth airfoil. I suspect this is because a KF airfoil is cheaper to make then a traditional smooth curved one. Of course, you can't argue that the RC aircraft still flies. Googlemeister (talk) 19:18, 16 August 2011 (UTC)[reply]
No argument about whether it can fly; the issue is whether it flies better or worse than a conventional airfoil. Nimur (talk) 19:27, 16 August 2011 (UTC)[reply]
If it was better then a conventional airfoil, it would have probably been used at least occasionally on conventional aircraft. That fact that it has not implies that there is something about it that drives aircraft manufacturers away from it for aircraft production. I suspect that it creates higher lift, but also higher drag, so it would be good for takeoff and landing but bad for cruise. Since most of the flight is in cruise, and you can have slats and flaps for takeoff and landing, KF doesn't see any use in aircraft which are concerned about fuel economy. Googlemeister (talk) 19:52, 16 August 2011 (UTC)[reply]

See Wing configuration. ScienceApe (talk) 22:09, 16 August 2011 (UTC)[reply]

The Wrights were the first to conduct actual experiments of wing shapes in a wind tunnel. It is that scientific approach for which they should be highly honored - all the others just made guesses aout the wings. Collect (talk) 22:45, 16 August 2011 (UTC)[reply]

AFAIK the closest thing to a rectangular wing profile is the diamond-shaped airfoil proposed for some supersonic aircraft, which would derive most of its lift from shockwaves on the top and bottom surfaces. (See Mach 1 and Beyond by Larry Reithmayer for more details.) FWIW 67.169.177.176 (talk) 06:43, 20 August 2011 (UTC)[reply]

Why are there two kinds of screws?[edit]

Why not just one kind? ScienceApe (talk) 22:07, 16 August 2011 (UTC)[reply]

Two? There are a lot more than two kinds of screw. Which two kinds are you asking about? Red Act (talk) 22:12, 16 August 2011 (UTC)[reply]
I'm guessing phillips head and flathead. From our article on Henry F. Phillips, who invented the Phillps head screw: "The importance of the crosshead screw design lies in its self-centering property, useful on automated production lines that use powered screwdrivers." Meelar (talk) 22:26, 16 August 2011 (UTC)[reply]
But that still leaves open the question of why the flat-head screw wasn't subsequently eliminated. Also, the Phillips-head has more than 1 profile, complicating matters further. StuRat (talk) 22:39, 16 August 2011 (UTC)[reply]
Flathead is easier to form and easier to turn without driver jumping out (both related to its straight sides though the former is less important now; the former also because it's cut all the way across instead of being sunk in as a hole). DMacks (talk) 23:42, 16 August 2011 (UTC)[reply]
Another advantage seems to be that only the thickness matters for a flat-head screwdriver. The width can be far narrower or wider than the screw, and it still works. StuRat (talk) 00:02, 17 August 2011 (UTC)[reply]
The page List of screw drives list many more than two kinds of screws. Dauto (talk) 22:36, 16 August 2011 (UTC)[reply]
(ec)You know, until now, I just assumed that philips head screws had been invented by Philips. Live and learn... --Kurt Shaped Box (talk) 22:38, 16 August 2011 (UTC)[reply]
The thing that first came to my mind was metric and imperial, maybe that's what the op meant? Vespine (talk) 23:04, 16 August 2011 (UTC)[reply]
Or may be he meant right handed and left handed screws which is the thing that came to my mind. Dauto (talk) 23:27, 16 August 2011 (UTC)[reply]
Also cross-threaded, double threaded etc., multiple pitch (a bit rare), wood and metal screws, concrete screws, ad infinitum. And English and US screws (different), as opposed to Metric screws etc. A fairly wide variety. And for all parents - the "impossible to unscrew" screw holding the battery lid in place on a toy. Collect (talk) 23:33, 16 August 2011 (UTC)[reply]
I was momentarily confused when a lady asked me whether I needed a positive or negative screwdriver. Cuddlyable3 (talk) 23:39, 16 August 2011 (UTC)[reply]
And what did they mean ? One with the X (or other shape) sticking out or indented in ? With connectors that's normally termed "male" and "female". StuRat (talk) 23:52, 16 August 2011 (UTC)[reply]
Cuddlyable3, that's great - had not heard that before but it's so clear it should be in common usage. Phillips looks like "+" and the slotted looks like "-". Plus and minus are so much easier to say and remember. -- Scray (talk) 03:24, 17 August 2011 (UTC)[reply]
If I was a little kid, 'impossible to unscrew' might sound like a challenge - yaknow, like 'child proof cap' and 'non-flammable'... :) --Kurt Shaped Box (talk) 23:43, 16 August 2011 (UTC)[reply]
I've yet to reach an age where "impossible to unscrew/dismantle/break" has stopped being anything but a challenge--Jac16888 Talk 01:15, 17 August 2011 (UTC)[reply]

I actually left out what I meant specifically on purpose because I was curious to know what people thought I meant. :P I was thinking, is this an obvious assumption? I thought most would prolly naturally assume I meant Philips head and flat heat, but a few would be confused. But yes, I meant Philips head and flat head screws. ScienceApe (talk) 03:23, 17 August 2011 (UTC)[reply]

Oh, a meta question? and we fell right for it :P Vespine (talk) 04:39, 17 August 2011 (UTC)[reply]
I have heard of companies using special screws in their goods so that only their own maintenance people can operate on them. Also, recently I tried to open a portable fan to oil it (it was slowing down and squeaking) and got easily got 3 out of 4 screws out with a Phillips Head driver. Then I looked at the last one and it was some kind of pentagon shape which I could not operate on. I think this was deliberate. All i could do was throw it out. It was not worth looking for and buying a driver I would never use again.
Also heard that a company actually PATENTED a type of screw, used those screws in their products, and refused to issue the associated screw drivers to anyone but their own people. That meant that neither you, nor any other maintenance people could legally operate on them. Sneaky, huh? Myles325a (talk) 06:18, 17 August 2011 (UTC)[reply]
Ingenious question, ScienceApe! Myles325a, as for what you say - sneaky, yes, but for me quite a disadvantage for the company. As my father is an electronics specialist and generally all-around handy and clever guy, he usually valued the ability of appliances to be opened and repaired or maintained at home, and this has trickled down to me. I know, I know, some things are not that easily repaired nowadays, i. e. modern TVs vs back-in-the-day CRTs, but back then - whenever something would go wrong with our old TV he'd just pull out his wiring diagram and welding iron and successfully attack it. Same goes for almost everything at home save for the icebox, which I don't remember him ever fixing. --Ouro (blah blah) 08:56, 17 August 2011 (UTC)[reply]
With straight head screws, close enough is usually good enough, in getting the thing to turn. A smaller than perfect driver (or a butter knife) is likely to get the job done. The same is true, to a lesser extent with phillips screws. But when you get into Allen screws, Robertson screws, security screws, and Torx screws, the match has to be perfect. If you need a number 2 Torx to open the battery cover, nothing else will do. There is a very high degree of torque applicable when one of the "perfect fit" drivers is required, and for the same screw thread in the same condition of rusted or overtightened, the straight or phillips would be likely to slip out and mangle the head of the screw. If you take a gadget to a building center or hardware store ("iron monger") you should be able to buy the perfect bit to loosen or tighten the screw. It is fairly cheap to pick up a kit of many assorted driver bits with a common handle, rather than buying the screwdrivers individually, when you know you might need several different styles and sizes over time. Edison (talk) 15:56, 17 August 2011 (UTC)[reply]

Surviving on raw food alone.[edit]

Twice now I have heard respected Professor Steven Jones say that humans have evolved to eat cooked food and we have evolved an inability to digest raw food. He says that if someone was to eat only raw food then that person would eventually die of starvation because our digestive systems are now no good for digesting raw food sufficiently. But I have heard of people that only eat raw food. I myself eat apples, carrots, cucumber and bananas, and feel satisfied afterwards. So surely he's wrong? Hear him make this claim here.2.24.232.12 (talk) 22:15, 16 August 2011 (UTC)[reply]

Fruits and vegetables are no problem, as many of those can be consumed raw. Sources of fat and protein are more of a problem, though. Meat, fish, eggs, and milk can be consumed raw, but this carries with it increased risks of disease. Beans really need to be cooked. Some nuts and seeds are OK raw, so that might be the best way to go. For fat, there's also avocado. Starches, such as from grains and potatoes, also typically require cooking.
Personally, I'd say it might be healthy to try to minimize cooked foods, but not to eliminate them altogether. If this practice means you eat more fruits and veggies and fewer steaks and potatoes, all the better. StuRat (talk) 22:32, 16 August 2011 (UTC)[reply]
You then won't have the energy to exercise enough to stay fit. I'm right now eating a big plate with some meat, about 200 grams of rice, 400 grams of potatoes and 300 grams of vegetables. Count Iblis (talk) 22:44, 16 August 2011 (UTC)[reply]
Actually, you can get plenty of energy (calories) in the form of sugars from fruit, and fats and proteins from nuts. I'd be more concerned about certain nutrients, like iron. StuRat (talk) 23:22, 16 August 2011 (UTC)[reply]
For other readers, the important quote is at 10:47 in the linked-to program: "Quite remarkably, we've lost the ability to digest raw food. If anybody was to eat nothing but raw food, as much as they like, in time they would starve to death. That's because we now depend on an external stomach, known as a deep fat fryer, or microwave."
However, it certainly is not true that people who don't eat cooked food all starve to death. There are both advantages and disadvantages to a raw food diet; see Raw foodism#Research. One of the disadvantages is indeed being at a greater risk for being underweight, but claiming that all raw foodists are going to starve to death is an extreme exaggeration. Red Act (talk) 22:45, 16 August 2011 (UTC)[reply]
Well, "in time" must be longer than seven years. My roommate of that duration eats only raw fruits and vegetables, fruit juices, yoghurt and cottage cheese, and sushi nori (that seaweed you wrap sushi with). He'll make a yoghurt shake with a raw egg thrown in maybe once a week. In the last seven years, he hasn't eaten cooked food once, nor any grains products, sugar, honey, meat, poultry, fish or shellfish. No ideology. He just can't stand the taste and texture of cooked food and animal flesh. Well, except mint or goldenrod tea, but I doubt that's contributing very much to his nutrition. Nevertheless, he's fit as a fiddle and not underweight at all....He just walked in the door and confirmed the "never". Dominus Vobisdu (talk) 23:08, 16 August 2011 (UTC)[reply]

Probably hyperbole. He was probably referring to the fact that humans can not anymore digest most cellulose present in plant cells. Chimpanzees and gorillas, however, can digest more cellulose and thus derive more nutrition from raw leaves and whatnot. Starch is also more digestible when cooked through starch gelatinization. Then there is the problem of getting enough of all the nutrients you need. This is why even vegetarians and vegans must find an alternative source of proteins and fats. You'll be surprised at the lengths primitive man went through just to fill in those gaps. Some of them survived into the modern age as culinary oddities, like eating insects, offal, or whale blubber.

Food is only as good as the amount of useful stuff you can actually absorb. The real question is what raw foods are you eating, not if you're eating solely raw or cooked or vegetables or meat, etc. Restricting yourself to a particular form or type of food always runs the risk of depriving yourself of something.

He is right though, in that we've actually evolved with our food. Milk is an example. Our ability to gain nutrition from milk is a very recent adaptation that seems to have manifested multiple times in different genetic populations (but most strikingly in European and African populations). Adult humans were never meant to be able to digest lactose, hence why some of us are still lactose intolerant.

Also note that satiety is not an indicator of receiving enough nutrients, you can feel satisfied if you eat enough amounts of wet wads of tissue paper. It's linked simply to the physical fullness of the stomach (hence why drinking soda for example, can induce a feeling of satisfaction even when you haven't eaten by expansion of the stomach with gas). The symptoms of Malnutrition are much more varied, depending on the exact deficiency.-- Obsidi♠n Soul 23:27, 16 August 2011 (UTC)[reply]

Having a full stomach is only one of many factors that make you feel like you're no longer hungry. If it was the only factor, then obesity treatments which restrict stomach size would be 100% effective. StuRat (talk) 23:45, 16 August 2011 (UTC)[reply]
Did I say it was? Of course not. But a very high success rate with the exception of the really really obese (even then a 57% success rate is no laughing matter) should give you an idea, yeah?-- Obsidi♠n Soul 23:54, 16 August 2011 (UTC)[reply]
Hard to know how much of that comes from the high buy-in, though. Once you've let them cut you open and put a rope around your stomach, you're going to be pretty committed to make sure it wasn't in vain. Not a thing you can really run double-blind studies to figure out how much of the effect comes from that and how much is from the intervention doing what it's supposed to. --Trovatore (talk) 03:51, 17 August 2011 (UTC)[reply]
Heh, okay we're veering off now. My original statement was that satiety is linked to the physical fullness of the stomach. And that is very much true. I mean, sheesh, isn't that a bit obvious? >_>
A distended stomach is the main signal that tells the body to stop eating. It's not fool-proof but it's the quickest indicator for the body. If we get the feeling of satiety only after we absorb enough nutrients in our blood stream, we would be eating for hours. But FWIW distending of the duodenum also functions in the same way. The peptide hormone of the small intestines cholecystokinin also induces the feeling of satiety if receptors in the stomach sense its presence, except that CCK usually only triggers after the stomach is already distended anyway, as its function is to tell the stomach to stop passing food into the small intestine temporarily while it digests fats from whatever was in there first.
Point is, just because you feel 'satisfied', like the OP said, it does not mean you are actually absorbing enough nutrition. It simply means you've eaten enough to fill your stomach, regardless if what you've eaten was actually nourishing or not.-- Obsidi♠n Soul 05:03, 17 August 2011 (UTC)[reply]
Obsidian Soul, this is a reference desk. Please supply references to support your claims. No, it is not obvious that the physical fullness of the stomach is the source of satiety. As the satiety article states, it has to do with certain hormones and the levels of blood sugar. Comet Tuttle (talk) 07:15, 17 August 2011 (UTC)[reply]
Jesus fucking christ, am I imagining it or are you guys being unnecessarily hostile to all my responses here so far? If blood sugar was the actual stimulus needed for you to stop eating, why then are you full after only a few minutes of eating? Nutrients are not absorbed that quickly for their presence in blood sugar to matter immediately. And you just linked me to Hunger (motivational state), not satiety, and no they are not the same.
And here you go. Please read to your heart's content:
Happy? And sorry, but the comments following my reply have been extremely insulting without even an attempt at disguising it. You could have found any of the references I gave in seconds. Yet assuming all I said were false was somehow easier. And is it really that dubious? I think I learned this in General Science class way back in elementary.-- Obsidi♠n Soul 07:53, 17 August 2011 (UTC)[reply]
Sorry you feel like you've been attacked. Having a full stomach certainly is one of the factors that makes us stop eating. However, the stomach can empty out fairly quickly, and we aren't always hungry again when it does. The stomach also stretches a great deal, and, depending on the many other factors that contribute to appetite, we may elect to keep on eating and stretch it out more. Just from personal experience, I know I often seriously overeat at holiday dinners. As for your original statement that being full doesn't mean all your nutritional needs have been met, I agree completely. StuRat (talk) 08:05, 17 August 2011 (UTC)[reply]
Sorry if I exploded. :3 Anyway, as I said, of course I agree. The psychology and physiology of hunger and satiety is far more complex than just filling the stomach, but gastric stretching is the main stimulus telling our brain to 'stop, I think we're full now'. And yes, blood sugar-related hunger is another thing, same thing with specific nutrient deficiencies, as I mentioned earlier. Both of which are already into the territories of starvation and malnutrition, i.e. long-term symptoms, not short-term satiety. You can still feel satiated, though for a shorter period, if you eat a lot of food quickly even when your body is already struggling in famine mode (not the diet fad craze). You feel full, but it doesn't mean you've had enough of all the nutrients you really needed. Notice also how people can be ravenous even if they've been hooked to dextrose in hospitals for quite a time and aren't in any danger of starvation, though again, hunger is not quite the same as satiety. -- Obsidi♠n Soul 09:01, 17 August 2011 (UTC)[reply]
Obsidian Soul, please calm yourself. The problem with your responses is that this is a reference desk and we are supposed to supply references to support the claims we make. I looked at two of the links you angrily provided above and did not see any support for your claim about satiety being linked to the physical fullness of the stomach. This is probably going to anger you more, but you need to point us to exact references, not just a list of books that you invite us to read in their entirety. (Doing so is like a reference librarian unhelpfully handing you a book instead of finding an answer for you.) As an aside, I'll point out that consuming two liters of water will physically fill the stomach but not eliminate the feeling of hunger. When you make statements like this that seem obviously doubtful, it increases the need for you to supply a reference. This is not a personal attack. We just need references supplied to support claims here. Comet Tuttle (talk) 08:37, 17 August 2011 (UTC)[reply]
¬_¬ <sarcasm>Oh? Did you really?</sarcasm> The links I gave are to specific pages discussing gastric stretching and nutrition. Google books can do that y'know. Anyway I'm annoyed that I have to stand on trial with you as the judge. I'm sure my temper will fizzle out later and I'll be reasonably ashamed... again (I do this a lot). But that's my usual reaction when people generally assume I'm pulling things out of my ass.
Your rationale of the water thing only makes it more obvious that you didn't read anything. See ref 1, notice illustration of rats. That is the same thing with liquids. Stomachs are not static. They can stop food from being passed instantly into the small intestine when they've not quite finished digesting it. Ever had dyspepsia? Solid food can be retained longer by the stomach hence it will distend. Liquids obviously will immediately seep out. They will pass on almost instantly into your intestines. Gas, however from carbonated drinks can. Try drinking two liters of coke. Call me in the morning.-- Obsidi♠n Soul 09:01, 17 August 2011 (UTC)[reply]
On the contrary; I did read two of your links, which did not discuss gastric stretching; I didn't read any of the others because after two fails, I concluded you had posted all the links in bad faith to try to brush off my criticism of your non-referenced answer. The above logic also is not referenced. I can't read the first link because Google Books is telling me I've reached my limit of reading that book, for some reason. Comet Tuttle (talk) 08:00, 18 August 2011 (UTC)[reply]
  • C. Bergh; S. Sjostedt; G. Hellers; M. Zandian; P. Sodersten (2003). "Meal size, satiety and cholecystokinin in gastrectomized humans" (PDF). Physiology & Behavior.
There is extensive experimental support for the hypothesis that the stomach plays an important role in the termination of food intake, i.e., satiety. Animals with open gastric fistulas, which prevent food from filling the gastrointestinal tract, overeat but will stop eating if the food is allowed to accumulate in the stomach and duodenum, and distention of the stomach causes satiety in animals and man.
Gastric distention during meal ingestion activates vagal afferents, which send signals from the stomach to the brain and result in the perception of fullness and satiety. Distention is one of the mechanisms that modulates food intake.
Recent studies (Janowitz & Grossman, 1949; Share, Martyniuk & Grossman,1952) have shown conclusively that food intake in dogs is influenced to a large extent by distension of the stomach whether the distension is achieved mechanically by a balloon or by calorically inert food. Further, distension of the stomach with a water-filled balloon inhibits sham drinking, a reflex that is abolished by vagotomy.
The role of gastric distension in bringing about inhibition of further eating and drinking has been demonstrated previously by various workers (Adolf, 1950; Holmes & Montgomery, 1960; Share, Martyniuk & Grossman, 1952; Towbin, 1949). The present study strongly suggests that this inhibition of eating is brought about by activation of the satiety centre through gastric afferents.
The stomach has an obvious role in the regulation of food intake, yet the mechanisms involved are only partly understood. The mechanisms related to stimulation of gastric mechanoreceptors involved in the capacity and propulsive functions of the stomach are best recognized where the gastric distension in association with a meal is an adequate stimulus that affects all types of gastrointestinal motor activity. In addition, gastric chemoreceptors have a major role in regulation of motility. The pyloric area senses the energy content of the food and thereby permits a fixed energy load to be emptied into the duodenum at a constant rate, regardless of the composition of the food.
There is, we feel, a strong case to be made for a major influence of gastrointestinal factors in the control of eating behaviour in humans. Moreover, the findings suggest that satiety and hunger are controlled by different gastrointestinal mechanisms. Gastric distension is perhaps the most important factor that stops people eating, but a true feeling of satiety also requires the presence of nutrients in the small intestine. Hunger appears to be little influenced by the amount of food in the stomach and appears to be more dependent on the nutrient load in the small intestine.
So don't give me that bullshit. I'm providing you the sources you demanded. Laziness and strange technical diffiulties that only seems to be affecting you is not a valid reason. You also have a browser, a search engine, and fingers. Use them. Or at least have the decency to admit you're waffling and wasting my time playing fetch the reference for you.
I'm spoonfeeding you. It's not my fault if you refuse to open your mouth. -- Obsidi♠n Soul 10:24, 18 August 2011 (UTC)[reply]
Thank you for the excellent references. If you had simply cited them in the first place, none of this would have happened. This is a desk where we provide references for querents, not direct them to search engines, or tell them to just believe what we type. Great work; thank you. Comet Tuttle (talk) 18:05, 18 August 2011 (UTC)[reply]
Except that no, no one else is providing references but me apparently. I certainly don't see you demanding any from the rest.
And no one else is having problems with links to Google Books but you apparently. Those Google links were also excellent academic references, pointing to specific pages I painstakingly searched and linked just for you (I even typed out a human readable title and author instead of just barelinks), and you're still accusing me of pointing you to a "search engine" when you're the one having problems accessing the links and didn't even read past two. Especially since the information I gave you can be checked in a few seconds of googling.
So please. Enough with the pompous pat-on-the-head and the hypocrisy on 'This is a reference desk, we are all snooty lazy bastards who don't assume good faith' when it obviously is not true.
Don't understand why you're still pissing me off? If you can't even agree that I was right in the first place, at the very least, have the guts to admit you were wrong in treating me that way. -- Obsidi♠n Soul 18:27, 18 August 2011 (UTC)[reply]
I agree that some of the requests for sources here are excessive. I apply the reverse of Carl Sagan's "extraordinary claims require extraordinary evidence", that is, "commonly accepted claims require little or no evidence", and "feeling full when your stomach is full" certainly seems to fall into that category. Now, it is sometimes true that common wisdom is mistaken, but then I'd expect the person questioning it to provide the proof (since "having a full stomach does not make you feel full" is itself an "extraordinary claim"). We can't just insist on an expert opinion every time somebody claims that 1 + 1 = 2.
Note that Comet Tuttle doesn't just do this to you, though. On the next question I was asked to provide sources, even though, as Looie said: "It is almost universally believed that long-term memory is stored in the structure of neural connections...". Now, perhaps Comet Tuttle doesn't know these things, but I don't consider it my job to provide an education to everyone here, so I generally ignore such frivolous requests. StuRat (talk) 17:59, 19 August 2011 (UTC)[reply]
I've slept on it. *sigh*. Not as ticked off as yesterday, what I could not stand was the assumption of bad faith from the offset that is not retracted but actually repeated ("not direct them to search engines") even when I did prove that I wasn't. And yeah I think I really did learn this way back in elementary. While I don't pretend expertise in anything, this is one of those things that asking a proof of is like demanding academic sources for heliocentrism. Though admittedly, a common point of confusion is that people assume hunger is merely the direct opposite of satiety and vice versa. Though the two overlap somewhat and the presence of one can cause cessation of the other, they are actually triggered by different things and comes in different combinations with short-term and long-term effects. Hunger reputedly has several kinds according to [questionable] diet fads, but all of them can be divided roughly into physical hunger (triggered by an empty stomach, the one that causes you to eat thrice a day) and emotional hunger (includes 'craving'), and at least two types of satisfaction, sometimes distinguished as the short-term satiation (stomach distension) and long-term satiety (having enough nutrients). See also Foods and Satiety (Lyly et al., 2009), pp.7–8. Our article on Hunger (motivational state) is wrong in this regard. If he had given a counter-statement and a proof, I would have happily provided a source in return. But requiring me to provide the evidence to disprove his claim on a common sense statement would touch off anyone, I gather. Anyway I apologize for my temper to Comet Tuttle.-- Obsidi♠n Soul 01:22, 20 August 2011 (UTC)[reply]
Raw foodism is very clear: it is a diet that is primarily raw food, not exclusively. Makes a big difference. But the weren't the Inuit eating only raw food? Without trees, you can't cook your food, can you?--Lgriot (talk) 08:27, 17 August 2011 (UTC)[reply]
I imagine they used blubber as fuel for fires. Without fire, they'd get mighty cold. (I believe whale oil was even used in lanterns in the developed world, before it was replaced by petroleum.) StuRat (talk) 08:54, 17 August 2011 (UTC)[reply]
The article isn't really "very clear" on that point. The article says "Raw foodism is the practice of eating uncooked ... foods as a large percentage of the diet." 100% is a large percentage, so that definition would include those people for whom 100% of their diet consists of raw food, so you can't logically deduce from that sentence that the article is claiming that 100% raw foodists don't exist. And poking around on the web, it's clear that at least some raw foodists are into eating 100% only raw food. For example, this raw food web site[13] says "Raw foodism is a movement in which the raw foodists will eat only raw, organic and unprocessed food." Red Act (talk) 15:10, 17 August 2011 (UTC)[reply]
I think you'd be hard pressed to find a steady supply of "apples, carrots, cucumber and bananas", as you know them, in the wild. Critters go nuts for human gardens for a reason : That stuff doesn't exist in the wild. We don't grow natural food, we grow food that's been specially bred to match our needs.
What does that have to do with your raw food question? Simple, if you're asking yourself if human evolution has moved us away from being able to eat "raw food", then it's not a fair comparison to compare to food specifically bred to be edible to humans.
I suppose that's not useful way of looking at it if you're trying to pick out the healthiest modern diet, but if you're going to bring evolution into it, you've got to also consider how radically our food supply, even our vegetables, have changed since we left our caves and became civilization-builders. 76.28.67.181 (talk) 08:58, 17 August 2011 (UTC)[reply]
OP here. Glad to see we're back on subject. I disagree with the previous answer.... the profs statement has nothing to do with whether food has changed over time. He is simply saying that if you eat only raw food then you will starve to death, and I can't see how that could be right. But then he's probably cleverer than me, so I'm trying to see how he can be right.Popcorn II (talk) 13:08, 17 August 2011 (UTC)[reply]
Some here have beaten up others for not referencing their common sense statements. Where are Steven Jones' reliable sources for his preposterous and extreme claim that we would starve to death if we didn't cook our food, that there is no possible uncooked combination of foods which would keep us healthy? What studies did he cite? Who are his example people who died from following a raw food diet? When did this remarkable adaptation take place, in his view? From listening to the recording, it sounds like he noted our digestive capabilities are different from those of chimps, and then he went on a spree of hyperbole and attempts at humor. Edison (talk) 15:42, 17 August 2011 (UTC)[reply]

To answer the question about the Inuit, they and other northern peoples eat a lot of fermented foods, fermentation being a form of cooking in that chemical reactions occur denaturing the proteins. μηδείς (talk) 18:26, 17 August 2011 (UTC)[reply]

Is fermentation "cooking?" Seems to be stretching the definition. Consider that chewing also involves a chemical reaction in which enzymes change the nature of carbohydrates, and that in some cultures parents chew the food for their tiny children, but chewing isn't cooking. Edison (talk) 18:32, 17 August 2011 (UTC)[reply]
Words have different senses. If you count processing meat in an exothermic process over time to make it digestible, then yes, sewing up shorebirds inside a seal-skin and letting them rot in their own heat so they become nice and soft and easy to consume does count as cooking. μηδείς (talk) 03:06, 18 August 2011 (UTC)[reply]

Mind uploading and transactional integrity[edit]

Is it known whether or not the human brain depends on transactional integrity in the changes that are caused when a neuron fires, and what the psychiatric effects of violating that integrity might be? Could this cause mind uploading to have harmful side effects if natural brain activity continued while the scan was in progress (or if the scan itself involved stimulating neurons), analogous to how a transactional database has to be write-locked while backups are made? NeonMerlin 23:53, 16 August 2011 (UTC)[reply]

I wouldn't think you'd attempt to upload the current thoughts when copying a brain to a computer. You'd just ignore the current electro-chemical signals, I suspect. StuRat (talk) 00:18, 17 August 2011 (UTC)[reply]
But "the current electro-chemical signals" may comprise crucial components of all your memory. As Nimur states below, we can't answer the question. Comet Tuttle (talk) 07:11, 17 August 2011 (UTC)[reply]
I believe memories to be stored in (relatively) static neurons and the connections between them, not as dynamic signals, which I believe only hold our current thoughts. Perhaps there's an exception for short-term memories, like a phone number you just looked up and are about to dial, but I think it would be safe to lose those during a memory upload. StuRat (talk) 08:10, 17 August 2011 (UTC)[reply]
Unfortunately, I have to call [citation needed] per Nimur below. Comet Tuttle (talk) 08:28, 17 August 2011 (UTC)[reply]
See Looie496 below. StuRat (talk) 17:48, 19 August 2011 (UTC)[reply]
That doesn't answer my question even if it's true, because as I understand it, the "static" connections change every time they're stimulated. What I'm talking about is, in the case where natural brain activity can be suspended during the scan, a larger-scale analog of the uncertainty principle -- a problem of how to observe something without altering it. NeonMerlin 15:18, 17 August 2011 (UTC)[reply]

This question can't be answered with any degree of scientific accuracy. Maybe you can start by reading about neuroscience to get some insight into the state-of-the-art scientific understanding of how thoughts and mental processes are represented in physiology. In truth, we don't know much at all about this. Our Cognitive neuroscience article has a very thorough list of current publications. To directly answer the original question, this is not currently known, because neuroscientists still don't have even a rudimentary understanding of the physiological substrates that implement cognitive processes. Nimur (talk) 00:54, 17 August 2011 (UTC)[reply]

Well, since I am a neuroscientist who works on learning and memory, perhaps I can chime in here. It is almost universally believed that long-term memory is stored in the structure of neural connections, and that dynamic activity holds information only briefly. The strongest evidence for this is that epileptic seizures, which massively disrupt brain activity, do not eliminate long term memory. (They can perturb it a bit, though, probably by inducing structural alterations.) Regarding the other part of the question, anything that produces a large amount of synchronized neural activity all at once can trigger an epileptic seizure (see Electroconvulsive therapy), causing a temporary breakdown in brain function although usually not significant long-term effects. Looie496 (talk) 16:51, 17 August 2011 (UTC)[reply]
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