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September 21

Turtle Star

Is there a star known as the Turtle Star? DuncanHill (talk) 02:29, 21 September 2010 (UTC)

Well, there's this one. WikiDao ☯ (talk) 02:37, 21 September 2010 (UTC)

There may well be, but Chrome can't connect to tattootribes.com DuncanHill (talk) 02:42, 21 September 2010 (UTC)

• Seems to be a reference to Mayan folklore, see this. This fits with the context in which I heard it, "Just by the shoulder of Orion, Bright Satellite outshone the Turtle Star". DuncanHill (talk) 03:05, 21 September 2010 (UTC)

I daresay that's the right answer. But just for interest, I searched on "Turtle Star" in Wikipedia and was intrigued to find out that there is an asteroid named Turtlestar, which was named after something called the Turtle Star Observatory (named in English even though it's in Germany). Putting the observatory's German web page into Google Language Tools for a translation, I was led to a page at the Minor Planet Center. If you go to this list and click on "Turtlestar", it explains:

(12053) Turtlestar = 1997 PK2

The Turtle Star Observatory, located in Mülheim/Ruhr, Germany, contributed follow-up observations for this object. This private observatory was built in 1995 by A. Boeker, K. Kleemann-Boeker, A. Martin and M. Tator and is named for a neighbor's turtle, which observed the construction with apparent great interest.

So apparently it's the Turtle Star-Observatory, not the Turtle-Star Observatory. --Anonymous, 17:42 UTC, September 21, 2010.

What is AGTP?

While watching some of my old DVDs, I came across this dialogue in Red Planet:

"I'm a geneticist. I write code, okay? "A", "G", "T", "P", in different combinations. Hacking the human genome, okay? I choose what, I choose where, and either your kidneys work or your grow a sixth finger. "

What does "A", "G", "T", "P" mean? -- 24.251.101.130 (talk) 06:28, 21 September 2010 (UTC)

Sure it's not A/T/G/C? Those are the standard DNA bases that encode the genome. DMacks (talk) 06:32, 21 September 2010 (UTC)

Nope, the actor definitely says "P". Thanks for the link to the correct information! -- 24.251.101.130 (talk) 06:39, 21 September 2010 (UTC)

The script, on page 59, clearly states A, G, T, P. However, the line is slightly different. It is: "I'm a geneticist. I write code. Like a hacker. Four elements, A-G-T-P, in different combinations. Hacking the human genome. I choose what, I choose where, and your kidneys work, or you grow a sixth finger." He refers to them as "four elements". I believe that it is safe to assume that the screenwriters simply got it wrong. It is A, G, T, C. They accidentally typed P and the actor recited what was on the page. It isn't the first time a movie has gotten some bit of science incorrect. -- kainaw™ 12:08, 21 September 2010 (UTC)

Is that the movie with the floating candies in a double helix, written in by someone who didn't know the difference between a base pair and a chromosome? The question of why Hollywood feels the need to show such gratuitous contempt for hard-scifi fans and refuse all access to anyone knowledgeable would be an interesting question for the Humanities desk. Wnt (talk) 15:18, 21 September 2010 (UTC)

No. That's Mission to Mars with Jerry O'Connell being the one who builds the DNA of his idea of a perfect woman out of M&Ms. Both movies were released in the same year, so it's not surprising that there would be some confusion between the two. Dismas|^(talk) 01:03, 22 September 2010 (UTC)

Physical exertion/weird taste

I have a question regarding the human body. Whenever I physically exert myself (mostly by continuous running), I eventually end up with a taste in my mouth similar to blood. I have talked to a few different people and they claim to have experienced this, including relatives of mine. What causes this taste to arise under near-exhaustion? ^{Here's the only} _{new, improved} Finalius! 11:33, 21 September 2010 (UTC)

As the major taste of blood is salt, I guess that the taste you experience after exercise is salt too. This paper says that after anaerobic exercise (near exhaustion) lactate, sodium, protein and RNAase concentrations increase in saliva. Smartse (talk) 14:23, 21 September 2010 (UTC)

Power supply for electricmotor

Can dc motor work on a.c. power supply?? —Preceding unsigned comment added by 115.248.134.49 (talk) 12:18, 21 September 2010 (UTC)

No. Dolphin (t) 12:22, 21 September 2010 (UTC)

Well, it probably would if you used a Rectifier to convert the AC to DC. Might also require a transformer. SemanticMantis (talk) 12:27, 21 September 2010 (UTC)

See Electric motor#Comparison of motor types. A Electric motor#universal will work on either. Something called a "DC motor" would appear, by definition, unsuited to AC operation. Edison (talk) 15:38, 21 September 2010 (UTC)

Has anyone tried hooking up a dc motor to an ac power supply? John Riemann Soong (talk) 20:26, 21 September 2010 (UTC)

My baby brother tried it and he says that it just vibrates. --Chemicalinterest (talk) 21:28, 21 September 2010 (UTC)

LAGRANGIAN AND HAMILTONIAN'S CONCEPT FOR GETTING EQUATION OF MOTION

I NEED SOME BASIC EXAMPLES LIKE GETTING EQUATION OF MOTION OF A FALLING BODY, SIMPLE PENDULUM BY LAGRANGIAN AND HAMILTONIAN METHODS. FURTHER, PLEASE PROVIDE ME ALL NECESSARY BASIC CONCEPTS OF THESE METHOD, AND WORKING RULE TOO.Ajay3HIMACHAL (talk) 14:29, 21 September 2010 (UTC)

PLEASE DON'T SHOUT - turn off your caps lock. --Cameron Scott (talk) 14:33, 21 September 2010 (UTC)

Did you try using a search engine such as Bing or Google? --Chemicalinterest (talk) 14:47, 21 September 2010 (UTC)

Nuclear power cost

Is it true that nuclear fission reactors are very expsnive to run? I thought they were quite cheap. What is the cost per megawatt from an "average" nuclear power plant and an average coal power plant? How does this compare to dependable renewables like hydro?--92.251.154.40 (talk) 14:42, 21 September 2010 (UTC)

We have an article on economics of new nuclear power plants that answers most of your questions. Gandalf61 (talk) 14:54, 21 September 2010 (UTC)

As well as an article on cost of electricity by source. But the figures vary and are hotly debated. Hydro power at its best is dirt cheap, but there isn't that much to go around.--Rallette (talk) 15:01, 21 September 2010 (UTC)

An important factor in their low expense is that nuclear operators don't pay insurance for damages over a set amount (that amount varies by country). Unlike a coal plant, a bad enough accident at a nuclear plant could make hundreds of square miles uninhabitable. If nuclear operators had to buy private insurance for that risk their rates would have to go way up to cover the premiums. See Price–Anderson Nuclear Industries Indemnity Act for the US version of this government largesse. --Sean 15:54, 21 September 2010 (UTC)

Not sure if you could technically call it largesse since the government has not really needed to pay for a huge nuclear accident... Googlemeister (talk) 16:36, 21 September 2010 (UTC)

Assumption of risk is an economic incentive, so I would definitely say it's largesse. Comet Tuttle (talk) 17:31, 21 September 2010 (UTC)

• I agree with Gandalf that you should check out those articles. The short answer is that nuclear power has high construction costs but cheap fuel. There's a similar dynamic in wind power, but you're dealing with smaller units, and don't have the nuclear industry's unique insurance problem. --M@rēino 19:46, 21 September 2010 (UTC)

It's worth pointing out that "construction costs" are not just physical construction, but regulatory, legal, and security related expenses. --Mr.98 (talk) 22:25, 21 September 2010 (UTC)

It's also worth pointing out that disposition and management of radioactive waste is an open problem - I don't think there is a single final repository operational on the planet, and hence estimating cost for disposal is essentially arbitrary. --Stephan Schulz (talk) 16:21, 23 September 2010 (UTC)

DNA

If you took the DNA out of a single cell, from a human or other large mammal, and stretched it out, how long would it be? --The High Fin Sperm Whale 16:25, 21 September 2010 (UTC)

DNA is an inherently 'stretchy' molecule, and it is much shorter if you keep it partially rolled up on its histone scaffold, but this page lists five textbook or encyclopedia sources reporting lengths between 1.5 and 3.0 meters. TenOfAllTrades(talk) 16:29, 21 September 2010 (UTC)

Each base pair "rung" on a DNA ladder (as it is conventionally shown as an extended double helix) is 0.33 nm tall (see DNA). The human genome is just over 3 billion base pairs, so the multiplication makes that out to be just under 1 meter. That's the haploid genome, though, so a diploid cell will have about 2 meters of DNA. Note, however, that it isn't one continuous ladder, but rather split into 46 separate pieces (the chromosomes). The website www.genomesize.com lists various genome sizes (in gigabases). Sperm whales aren't listed, but elephants are, at a (haploid) genome size of 4.03 Gbp, or 2.66 m of DNA per cell. (Elephant shrews, on the other hand, are at 5.98 Gbp, or 4 m.) -- 140.142.20.229 (talk) 18:48, 21 September 2010 (UTC)

gold purity

If you had a gold sample, what is the highest amount of impurity that would be undetectable by current testing methods? Googlemeister (talk) 16:38, 21 September 2010 (UTC)

Define "current testing methods". Accelerator mass spectrometry has demonstrated a routine detection ability of about 1 part in 10¹⁶, and in certain research applications is been made many orders of magnitude more sensitive than that (e.g. 1 in 10²⁴). However, AMS is crazy expensive, and hence would not be a normal test anyone would do on gold. So, I think the answer is going to be determined mostly by the choice of test(s) you are going to consider. Dragons flight (talk) 17:32, 21 September 2010 (UTC)

I mean by methods that might be used on an industrial scale, such as a refiner. Googlemeister (talk) 18:08, 21 September 2010 (UTC)

It will depend somewhat on which impurity you are worried about, but standard chemical analysis can easily detect parts per million levels, whereas you would need to take lots of expensive precautions to go lower than parts per billion levels. The main problem, especially for a refinery which does many such analyses, is impurities in the chemicals you use for the analysis and any contamination of the equipment. Gold bullion is 99.999%, that is a maximum of 10 ppm impurities, so that gives you some idea of the scale refiners are working to. Physchim62 (talk) 18:41, 21 September 2010 (UTC)

ghost light

After staring at a bright light for a few seconds then turning off the light, one notices, behind closed eyelids, a bright spot of light that disappears after 15-30 seconds. What causes this ghost light? WSC —Preceding unsigned comment added by 66.27.180.64 (talk) 16:44, 21 September 2010 (UTC)

At afterimage it says:

Afterimages come in two forms, negative (inverted) and positive (retaining original color). The process behind positive afterimages is unknown, though thought to be related to neural adaptation... Negative afterimages are caused when the eye's photoreceptors, primarily those known as cone cells, adapt from the overstimulation and lose sensitivity.

--Anonymous, 17:10 UTC, September 21, 2010.

It's due to neural adaptation. See also Optical illusion for many other interesting effects like that. WikiDao ☯ (talk) 17:52, 21 September 2010 (UTC)

Direct vision/averted vision

According to John Bortle, M33 should be visible in direct vision if the sky is dark enough, see here. Bortle class 1 or 2 is dark enough for this, while it is visible with averted vision at class 4 or better.

However, this is disputed here. Where I live the skies are not dark enough to be able to see M33 with the naked eye at all, but I have experienced the same thing about averted/direct vision. When you look at a faint object that is clearly visible and you don't consciously use averted vision, you may still see it because of a minimal unconscious use of averted vision, while you have the feeling that you are seeing it in direct vision. If you force yourself to stare at the object directly, it becomes much fainter. But I have to say that looking at an object in that way is not natural. If you do the opposite and use averted vison consciously, the object becomes far more apparant than if you just look at it normally.

If my eyes are fully dark adapted then precisely in the direction of view, there seems to be something like a weak haze. This is effect is not noticable if I'm just a few minutes outside in the dark. Only after 20 to 30 minutes does this more narrow difference between 100% direct vision and not 100% direct vision become apparant. So, perhaps one should distinguish betwee different levels of averted vision? Count Iblis (talk) 18:19, 21 September 2010 (UTC)

I'm not too sure what your question is. Do you want an answer in terms of rods and cones and neurons...? WikiDao ☯ (talk) 21:54, 21 September 2010 (UTC)

Yes, if an explanation can be given. So, the question is about being fully dark adapted. Then it seems that precisely in the view of direction your eyes are lot less sensitive to light, compared to looking just a little away from the object, but not so much away that you are engaging your averted vision. Count Iblis (talk) 00:36, 23 September 2010 (UTC)

Okay, well, dark-adapted vision explains how rod cells are the cells in the retina most involved in night vision. Then, the fovea article says:

The human fovea has a diameter of about 1.0 mm with a high concentration of cone photoreceptors. The center of the fovea is the foveola - about 0.2 mm in diameter - where only cone photoreceptors are present and there are virtually no rods.

The fovea is what you use to see "precisely in the view of direction your eyes", and you cannot see well with it in the dark because it has relatively few rod cells in proportion to cone cells compared to the rest of the retina. The foveola would then be even more precise in the same way, which may account for the third perception you are asking about, when you look "just a little away". That could also be due to slight involuntary movements of the eye called saccades, which may bring the image of the object very briefly (and imperceptibly) just enough right outside the fovea to activate some rod cells. WikiDao ☯ (talk) 02:10, 23 September 2010 (UTC)

Thanks for explaining! Count Iblis (talk) 14:34, 23 September 2010 (UTC)

Liquid helium production

How is liquid helium cooled before it is liquefied? I looked at helium and liquid helium but only saw that it is cooled to a low temperature than liquefied through expansion. How is it cooled to that low temperature? Thanks, --Chemicalinterest (talk) 18:35, 21 September 2010 (UTC)

Liquid hydrogen. It's the only readily available coolent that can get the helium down to 40–45 K (the Joule–Thomson inversion temperature). The hydrogen itself has to be cooled by liquid nitrogen before it can be liquified. Physchim62 (talk) 18:45, 21 September 2010 (UTC)

The history of attaining successively colder temperatures (and liquefying successively lower boiling gases: nitrogen, then oxygen, then hydrogen, and finally helium) is a fascinating one, and our articles really don't seem to do it justice. Heike Kamerlingh Onnes was the first person to liquefy helium, but he was in competition with another scientist (whose name eludes me at the moment) to be the first. I read a fascinating book on the subject a few years ago. It might have been this one [1], but I don't really recall.

As for the specific process Onnes used, he liquefied different gases and then used them to cool the next gas to be liquefied. If I recall correctly, he made liquid air(essentially liquid nitrogen) and used it to cool hydrogen, which was liquefied to cool helium, which was then liquefied by the aforementioned Joule–Thomson effect. Buddy431 (talk) 19:18, 21 September 2010 (UTC)

Edit: yeah, it's definitely the Absolute Zero book that I linked. It's pretty good for the non-expert, if you're interested in this sort of thing. It looks like you can read most of it online at Amazon, which sort of defeats the purpose of selling it... Buddy431 (talk) 19:23, 21 September 2010 (UTC)

Even more to add: it looks like PBS made a two hour NOVA episode about the subject (based on Shachtman's book that I linked). I haven't seen it, but they usually do a pretty good job with science subjects. It looks like I'm going to have to go to the library and see if they have that episode. Buddy431 (talk) 19:27, 21 September 2010 (UTC)

Here's the website for the NOVA episode. Buddy431 (talk) 19:28, 21 September 2010 (UTC)

From what I understand, in order to create liquid helium, you would compress standard helium, remove the heat created by the compression (while maintaining pressure) and then expand the helium. If your original compression ratio was sufficient, then you should be able to remove enough heat (using the above liquid hydrogen or liquid nitrogen) that when you expand the helium you will get some condensate. Googlemeister (talk) 19:47, 21 September 2010 (UTC)

Maybe some info can be placed in the articles by some of the more knowledgeable people about the process for liquefying helium. I am better at writing simple articles. --Chemicalinterest (talk) 19:53, 21 September 2010 (UTC)

I am a big documentary fan, I watch lots and lots of documentaries, and "Absolute Zero" is still in my fav docos of all time. I can not recommend it highly enough. It's a topic almost everyone thinks there's "nothing" to, the subject is so personally familiar to everyone, you can't not take it for granted. But the story of how people first tried to explain "cold" and incrementally discovered how to control it is actually incredibly fascinating. Vespine (talk) 23:19, 21 September 2010 (UTC)

As far as liquid helium production is concerned, I think this is involved Hampson–Linde cycle . Vespine (talk) 23:47, 21 September 2010 (UTC)

It's a Hampson–Linde cycle once you've cooled the gas down to 40 K. Above about 45 K, the Hampson–Linde cycle won't work, because the Joule–Thomson coefficient is negative: that means that helium warms up as it expands is it starts at more than about 45 K (the exact temperature depends on the pressure). This is why you need liquid hydrogen to cool the helium down before you can run the Hampson–Linde cycle. Physchim62 (talk) 00:50, 22 September 2010 (UTC)

Atmospheric tides of the moon

Tidal forces.

What makes the lunar tides effect on the atmosphere strongest at the 4 o'clocks & weakest at the 10s? I would think it would vary with the moon's phase & its rise and set times. —Preceding unsigned comment added by Woodelf68 (talk • contribs) 19:19, 21 September 2010 (UTC)

Can you point to a source discussing this? Our article on atmospheric tides doesn't mention it. — Lomn 19:48, 21 September 2010 (UTC)

Well, our atmospheric tides article does claim that atmospheric tides are "are generated by the motion of the Earth's oceans (caused by the Moon) and to a lesser extent the effect of the Moon's gravitational attraction on the atmosphere." So maybe the the diagram on the right, from our Tide article, helps some? I'm not entirely sure what you are asking, Woodelf68. WikiDao ☯ (talk) 20:53, 21 September 2010 (UTC)

It sounds like you are actually describing solar atmospheric tides, which are sun-synchronous (so at the same time each day) and have a 6-hour component of oscillation. Lunar atmospheric tides are generated by the same mechanism that produces ocean tides, so they should have the same (or perhaps orthogonal) timing as ocean tides. Franamax (talk) 18:02, 22 September 2010 (UTC)

Richard_Lindzen#Atmospheric_tides also William M. Connolley (talk) 18:22, 22 September 2010 (UTC)

this

why cant i find articles about this event http://www.documentingreality.com/forum/f166/police-shoot-couple-execution-style-15488/ —Preceding unsigned comment added by Kj650 (talk • contribs) 20:46, 21 September 2010 (UTC)

I think that's a bad link. I couldn't see the video there. If you give a better link or explain your question better, we might be able to help you find more information about your topic of interest. WikiDao ☯ (talk) 21:15, 21 September 2010 (UTC)

the link works —Preceding unsigned comment added by Kj650 (talk • contribs) 21:19, 21 September 2010 (UTC)

The link only works if you're a member of that forum. And since it's invite-only it's not very useful. APL (talk) 21:45, 21 September 2010 (UTC)

try this http://www.youtube.com/watch?v=7K3j2UfwDTo —Preceding unsigned comment added by Kj650 (talk • contribs) 00:58, 22 September 2010 (UTC)

Looks like it originally came from the History Channel. I couldn't quite catch the names of the deceased. But as explained in the video, police snipers shot to wound and disable; the wife then shot and killed her husband and then herself. Happens all the time; why would you expect to find an article about that one incident? WikiDao ☯ (talk) 01:09, 22 September 2010 (UTC)

It does not happen all the time, and, as I demonstrated below, something like this is quite likely to get written up in at least the state newspapers. Buddy431 (talk) 01:46, 22 September 2010 (UTC)

a news article i would expect —Preceding unsigned comment added by Kj650 (talk • contribs) 01:41, 22 September 2010 (UTC)

Here are a couple articles I found: [2], [3], using Google News Archive. Buddy431 (talk) 01:45, 22 September 2010 (UTC)

Okay, good work getting their names. That got me to our article Keith Haigler, which describes the incident in the video. WikiDao ☯ (talk) 01:51, 22 September 2010 (UTC)

September 22

Cancer

I heard that they can take a sample of tissue that is cancerous (for example some breast tissue in breast cancer) and know how serious it is and how far it advanced. How is one piece of cancer tissue different than another? How can they tell its more serious than another? —Preceding unsigned comment added by 76.169.33.234 (talk) 01:38, 22 September 2010 (UTC)

There are a number of ways of ranking cancer severity, including staging. In addition to looking at metastasis and lymph node involvement, one can perhaps look for the level of cellular change to determine dysplasia, metaplasia, carcinoma-in-situ, etc. DRosenbach ^{(Talk | Contribs)} 03:48, 22 September 2010 (UTC)

Cancerous cells can look like normal cells, only growing out of control, or they could have say, their lung cell genes kind of too mutated that they look disorganised. John Riemann Soong (talk) 16:48, 26 September 2010 (UTC)

house foundation

how to repair house foundation from water damage? its slanted —Preceding unsigned comment added by Kj650 (talk • contribs) 04:20, 22 September 2010 (UTC)

There's no solution to that that doesn't cost a hell of a lot of money, so you better get professional advice. Looie496 (talk) 05:04, 22 September 2010 (UTC)

You need a house jack. You also need someone who knows how to operate it. You also need someone who can rebuild the foundation once your house is jacked up, and then replace the house upon it. All very expensive. This is not something you can do yourself, unless you happen to be the sort of person who owns a foundation repair company. --Jayron32 05:09, 22 September 2010 (UTC)

I doubt we can give you advice, but for sure we can't give you advice without a photo. Ariel. (talk) 08:27, 22 September 2010 (UTC)

Iodized salt

I saw that the low-sodium iodized salt supermarkets sell contain sodium chloride, potassium chloride and potassium iodide. I know that sodium chloride and iodine is important for the human body, but is potassium chloride and iodide (the compound itself) beneficial, or required by the body in any way? YOSF0113 (talk - contributions) 06:12, 22 September 2010 (UTC)

Yes. Once dissolved, potassium chloride breaks into its respective ions, potassium and chlorine. Potassium has many important biochemical functions, most notably its role in the "sodium-potassium pump". Nimur (talk) 06:48, 22 September 2010 (UTC)

The beneficial effect of potassium chloride in low-sodium table salt is that it isn't sodium chloride. Our article on low sodium diet describes why it is beneficial for some groups of people to limit their intake of sodium ions, and one simple way to do this is by using low sodium salt instead of normal table salt (although it's unlikely to be sufficient on its own without other changes in diet). Potassium iodide is added as a source of iodine; potassium iodate can be used as well: either compound can be used by the thyroid gland. You could use sodium iodide for this purpose, but potassium iodide is cheaper (about 40% cheaper for kilogram quantities, probably even more so for bulk quantities). Physchim62 (talk) 11:23, 22 September 2010 (UTC)

Potassium is absolutely critical for life, but the body doesn't eliminate it very rapidly, so the great majority of people get enough in their diets without having to do anything special. See hypokalemia (i.e., "low potassium") for the few exceptions. Looie496 (talk) 17:15, 22 September 2010 (UTC)

I wonder if those people should avoid adding salt to their diet instead. Imagine Reason (talk) 00:30, 24 September 2010 (UTC)

transmission

where the multiple circuit lines used.. —Preceding unsigned comment added by Chanuu.. (talk • contribs) 06:31, 22 September 2010 (UTC)

Would you clarify your question? "Multiple lines" sounds like parallel communication, but beyond that I can't tell what you're looking for. — Lomn 13:55, 22 September 2010 (UTC)

The question might also apply to an electrical power system, where parallel lines are used to maintain continuity of service when one line trips and avoid overloads when heavy currents are carried between buses. Within a single phase on a single line on a single transmission tower, multiple parallel bundled conductors, spaced a short distance apart apart, are used to keep the impedance lower and to reduce radio interference [4]. Edison (talk) 19:10, 22 September 2010 (UTC)

is sulfamethoxazole is short acting or intermediate acting sulfonamide

Respected sir, you are mentioned "sulfamethoxazole" as short acting sulfonamide but in the book of pharmacology by "kd tripathi" sulfamethoxazole is mentioned as intermediate acting sulfonamide.could you please explain about it —Preceding unsigned comment added by 117.199.244.167 (talk) 09:48, 22 September 2010 (UTC) Question reformatted to return within window. Caesar's Daddy (talk) 10:01, 22 September 2010 (UTC)

Actually, our article classifies it as an intermediate-acting sulfonamide, so there is no conflict with your reference. This seems fairly evidently true by it's half life of 10 hours. Regards, --—Cyclonenim | Chat  14:20, 22 September 2010 (UTC)

Can giraffes cough?

My work's intranet home screen includes a random "fact" and I just saw one that I don't quite believe: Giraffes don't cough. I googled it and got the answers- yes they can and no they don't. So this is bugging me. The Wikipedia article says that the males make a coughing noise, but is that an actual cough as in, clear your throat/cough up your lungs type cough? Do they actually cough or just make cough-like noises? MorganaFiolett (talk) 12:07, 22 September 2010 (UTC)

I've looked around and can't find a specific reference, but I don't see any reason to believe they wouldn't cough. They have similar features in that region as we do, just somewhat elongated. They still have a long trachea, and I can't find a reference to say they don't possess the C fibers needed to initiate the cough. Furthermore, if we humans have to cough regularly to effectively clear out comparatively short airways, I'd imagine they have an even greater need to do so. Regards, --—Cyclonenim | Chat  14:15, 22 September 2010 (UTC)

• Good question. Our article on Cough is absolutely terrible for non-humans. Our giraffe article claims that "Courting males will emit loud coughs", but that claim isn't sourced. --M@rēino 14:24, 22 September 2010 (UTC)

Google scholar coughed up the snippet "Cough is not a feature of the giraffe's behaviour possibly because of the high protective aryepiglottic folds and herbivorous diet." [5] (D. F. N. Harrison, "Biomechanics of the Giraffe Larynx and Trachea", Acta Oto-Laryngologica 1980, Vol. 89, No. 3-6 , Pages 258-264 [6]). Unfortunately I can't view the study. ---Sluzzelin talk 16:29, 22 September 2010 (UTC)

Just curious, but why would a herbivorous diet affect the frequency of coughing? Fair play on the aryepiglottic folds thing, though. Regards, --—Cyclonenim | Chat  17:26, 22 September 2010 (UTC)

I guess because they chew cud. (Not all herbivores chew cud, of course, but giraffes do). Many captive ungulates die when cud gets into the wrong pipe, say, after anesthesia. --Dr Dima (talk) 18:28, 22 September 2010 (UTC)

I didn't understand your last point, Dima -- humans can die if they aspirate regurgitated food after anesthesia, so what does that have to do with ungulates, ruminants or giraffes? DRosenbach ^{(Talk | Contribs)} 20:19, 22 September 2010 (UTC)

... and cud-chewers and other herbivores do cough, though perhaps not in quite the same way as humans? Dbfirs 05:59, 23 September 2010 (UTC)

Fleischmann–Pons experiment

Yesterday in the course of a public lecture on financial engineering, the speaker mentioned in passing that the Fleischmann–Pons effect, widely considered discredited, was actually valid, and the attempts to reproduce it failed because they weren't done right. That's all he said about that. I haven't heard any updates since the time this was first in the news. Was there something more recent that I missed? Michael Hardy (talk) 16:53, 22 September 2010 (UTC)

There are plenty of claims, but not very many that are taken serious. If you have the stomach for it, talk:Cold fusion has been a battleground for the last year or so, and you can probably find all the claims and counterclaims there. Basically, something interesting may be going on, but it's almost certainly not fusion, and almost certainly not a real source of usable energy. The slope from reasonable to fringe to total cook is fairly steep and quite slippery in that field. --Stephan Schulz (talk) 17:06, 22 September 2010 (UTC)

Diastolic Dysfunction

Our article on the above topic says:

Some causes of left ventricular stiffening include:

* high blood pressure (i.e. hypertension, where, as a result of left ventricular muscle hypertrophy to deal with the high pressure, the left ventricle has become stiff)

* aortic stenosis of any cause (here as with hypertension, the ventricular muscle has hypertrophied and thence become stiff, as a result of the increased pressure load placed on it by the stenosis)

*scarred heart muscle (e.g. occurring after a heart attack) (scars are relatively stiff)

* diabetes (stiffening occurs presumably as a result of glycosylation of heart muscle)

* severe systolic dysfunction that has led to ventricular dilation (i.e when the ventricle has been stretched to a certain point, any further attempt to stretch it more, as by blood trying to enter it from the left atrium, meets with increased resistance - it has become stiff

* reversible stiffening as can occur during periods of cardiac ischemia

Does anyone know of other causes, or is this "Some" weasel wording? If there are other known causes, could the responder elucidate? Thanks Bielle (talk) 18:02, 22 September 2010 (UTC)

Without comment on the specifics...

• I don't see "some" here as an instance of weasel words, provided the list isn't in dispute. Sources would certainly help, but it's no more weasel-ey than "some major US cities are NYC, Chicago, and LA". Contrast with "some say that Chicago is better than NYC", where "some" props up a questionable claim.
• All that said, if "some" is a matter of concern, go ahead and remove it. "Causes of left ventricular stiffening include:" is also a perfectly good list introduction, and (perhaps unlike this answer) avoids unnecessary words. — Lomn 18:16, 22 September 2010 (UTC)

I think death causes that too, OP, if you are trying to assemble a complete list. ;) WikiDao ☯ (talk) 19:22, 22 September 2010 (UTC)

What I am really asking is whether or not there are other known causes, death aside. The use of "some" suggests that there are. And, if there are others, could someone tell me about them? Thanks. Bielle (talk) 21:18, 22 September 2010 (UTC)

One additional cause would be hypertrophic cardiomyopathy. Although not discussed in depth in our article, diastolic dysfunction can be seen in genetic forms of cardiomyopathy (see [7] for example). --- Medical geneticist (talk) 21:38, 22 September 2010 (UTC)

There's heaps of things that cause diastolic dysfunction and the article list is by no means exhaustive. Death actually isn't one of them, since death produces an absence diastole and systole, and the definition of diastolic dysfunction requires that diastole is happening. But if you want to think about this in broader terms, you can make a big list of anything that impairs myocardial compliance under headings of precardiac, intracardiac and postcardiac. Precardiac causes are the least common, and all I can really think of would be things that prevent venous return to the heart, such as haemorrhage, peripheral vasodilation or inferior vena caval obstruction. Intracardiac causes include mitral valve and aortic valve diseases (prolapse and stenosis), the cardiomyopathies (dilated and hypertrophic), myocardial lesions (infarction, tumour eg rhabdomyosarcoma, myxoma, deposition diseases like amyloidosis, sarcoidosis, for example). The major post cardiac cause is atherosclerosis (or peripheral vascular disease) and hypertension. Type 2 Diabetes is a major cause of atherosclerosis and hypertension, and this is probably the most significant contribution diabetes has to diastolic dysfunction. Further to these pathophysiological causes, there's also exogenous causes, particularly drugs - prescribed and non-prescribed (chronic cocaine use can produce spectacular myocardial hypertrophy, but this is also true of anything that is used long term that increases the rate or force of heart muscle contraction). This isn't an exhaustive list either! Cheers, Mattopaedia ^{Say G'Day!} 07:20, 23 September 2010 (UTC)

My speculation about "death" was as a "cause" of "left ventricular stiffening". I concede that "not functioning at all" is a stretch of what is meant by "dysfunction." But would not death cause "stiffening" in the associated smooth muscle, at least for a few hours? WikiDao ☯ (talk) 20:21, 23 September 2010 (UTC)

Thank you all! Bielle (talk) 02:33, 26 September 2010 (UTC)

Why does it take so long to get toxicology results?

Our article Forensic toxicology describes various tests used to see what drugs, poisons, or other substances were present in the body of a person who died under questionable circumstances, but does not address the long time frame. News stories typically say the toxicology reports take "up to two months." On TV crime shows, (granted, they are not reality) they put a tiny sample of blood or tissue in a Mass spectrometer and the peaks in the graph indicate the elements and compounds present. I have had samples of industrial substances analyzed by mass spec and gotten results in less than a day. Chromatography in various forms is another tool. I do not understand why either test would consume 8 weeks, or perhaps 6 weeks allowing for shipping and report writing. Are the samples from one individual really undergoing analysis on a daily basis for a month or two, or do they wait in queue then get a few days' analysis? Blood alcohol can be measured pretty quickly. My hospital's lab can do a wide range of tests on blood or urine overnight. Are there chemical reactions which take weeks to arrive at a result, which the delivery of quicker tox results must await? Edison (talk) 18:25, 22 September 2010 (UTC)

How many people are doing tox screens and how many tox screens do they have to do? Googlemeister (talk) 19:32, 22 September 2010 (UTC)

Probably not a reason, actually. The Tox people have a limited sample, and they can't do all the possible tests on it: simple things (like blood alcohol) can be done quickly, but anything complicated might have to wait for a standard to be delivered. Physchim62 (talk) 19:40, 22 September 2010 (UTC)

Do you think there is any particular test which resides in a GCMS. some fancy analyzer or even a test tube for more than a week? Is the rest just a queue/backlog delay and a delay for retest to confirm the presence and concentration of substances of forensic interest? If it were of paramount national interest, and prompt results were demanded, would the 8 weeks turn into 24 or 48 hours? Edison (talk) 04:35, 23 September 2010 (UTC)

There are at least some examples of tests that really do take weeks of lab time. The most obvious are ones based on forming bacterial cultures to detect pathogen types, which for some strains of pathogens can be very slow / difficult due to the bug's reluctance to grow in vitro. (Though in recent years, molecular and DNA tests have reduced the need for culturing in many cases.) Dragons flight (talk) 06:11, 23 September 2010 (UTC)

In autopsy specimens, a rather large standard battery of drugs and other substances is usually tested for, and this includes a range of opioids and benzodiazepines, alcohol and other illicit substances like ephedrine derivatives (speed, ecstasy, ice, etc), cocaine, cannabinoids, as well as a large range of prescription drugs like paracetamol ( aka acetominaphen), salicylates, diuretics, antihypertensives and other drugs that effect heart function, antidepressants and antipsychotics. Usually this is performed on one or two tubes of blood, which needs to be shared out for all those different GCMS runs, which are all batched together so sample from a number of autopsy cases are analysed together. This all takes a fair bit of time. Then the results need to be reviewed and validated by an experienced toxicologist, and those results are then interpreted in the context of the autopsy findings by the forensic pathologist before the report is prepared for the coroner. If some of the results are dubious and restesting is required, the process can take months. Usually when its a famous person, this process is fast-tracked, and it still takes a few weeks. Mattopaedia ^{Say G'Day!} 07:42, 23 September 2010 (UTC)

Another possibility may simply be logistical. Most local police agencies (except in larger cities) do not have their own criminologists, and even those which do lack some of the more sophisticated equipment, usually for cost reasons. For them, they must ship the material to be tested to a larger agency (in the U.S., typically the state police or a large nearby city), where it must wait in the queue along with all of the tests that agency is doing for itself. — Michael J 14:48, 25 September 2010 (UTC)

What places endangered by global warming would make good vacation choices?

What if I decided to spend my next vacation somewhere that has a good chance of being underwater, uninhabited, or radically changed by global warming in my lifetime? Is the environment changing so fast that it's plausible that I could tell my grandchildren that I visited (place x) while it was still above the waves? Or no? What places would make good choices for such a trip? (I'm planning to live about 50 years longer.) -FisherQueen (talk · contribs) 22:07, 22 September 2010 (UTC)

Visit the Maldives. At only 8 feet (max) above sea level, they will be the first to disappear if sea levels rise. Dbfirs 22:34, 22 September 2010 (UTC)

One travel blog also suggests Chacaltaya (too late, the glacier's gone), the Greenland ice sheet, Bangladesh, the Himalayas, Kiribati, the Great Barrier Reef.[8]. I'd throw in skiing holidays in some of the lower Alpine regions or at Snoqualmie. ---Sluzzelin talk 23:30, 22 September 2010 (UTC)

The North Pole will look a lot different. Your grandchildren will know that Santa Claus had to move from the North Pole to the South Pole because of global warming. Count Iblis (talk) 00:45, 23 September 2010 (UTC)

Well it would have to rise by about 10m before inundating the National Mall, but that's a nice place to visit (and knowing the way they are down there, I'm sure they'll just put up some concrete barricades or something lol;). You can see a map of what various sea-level changes would do to anyplace in the world on the Global Sea Level Rise Map. Our Current sea level rise article expects there to be a maximum rise of 2m over the next century, but most likely less than half that. WikiDao ☯ (talk) 04:41, 23 September 2010 (UTC)

Go check out the polar bears before they go extinct. Just don't try to feed them... Matt Deres (talk) 13:12, 23 September 2010 (UTC)

Venice is an obvious answer, but New Orleans may be a good choice as well. As the ocean level rises it will become more and more vulnerable to hurricanes.

Have you considered checking out animals the may soon go extinct?

Or be in Florida to watch the final Space Shuttle launch. Tell the grandkids that you can remember when USA had a man-in-space program. APL (talk) 16:34, 23 September 2010 (UTC)

Sea level rise is unlikely to be more than 1m in 50 years, and likely less than that. For radical change a melting glacier is a pretty good choice; there are lots of those (retreat of glaciers since 1850) William M. Connolley (talk) 17:28, 23 September 2010 (UTC)

I'd visit the future former Glacier National Park (U.S.). -Atmoz (talk) 17:56, 23 September 2010 (UTC)

Some scientist are beginning to think -and find archaeological evidence for- major climate shifts that can happen abruptly. So... Would it not impress your grandchildren more if you just stayed where you are? When the climate flips, you can recount to them: Oh yes! I can remember when there were herds of people, roaming across these plains as far as the eye could see. There were millions of them, all driving around in auto-mobiles. They slept in very tall air-conditioned buildings which were lit by electricity. They burnt millions of gallons of kerosene each day just so they could fly to far off places in aluminium cans -all for the fun of it. Then you can explain to them what a motor car was and were electricity used to come from and why they have no friends to play with etc. Of course, you run then run the risk of them suspecting that granny is prone to exaggerate more than just a little bit. Six horses pulling a cart perhaps, but carts with 250 of them hidden under a hood...?--Aspro (talk) 19:17, 23 September 2010 (UTC)

"I remember when petroleum was cheap enough to burn."

Along those lines, some people predict that fast world travel will become prohibitively expensive in our lifetimes. If that turns out to be true, just visiting distant lands would be enough. APL (talk) 22:10, 23 September 2010 (UTC)

Ha! Really think that would happen? Well it could. I don't think the environment is changing fast enough in any place, unless there is a tsunami on one of those islands... then the environment will change rapidly. :) --Chemicalinterest (talk) 11:11, 26 September 2010 (UTC)

Kiribati is worth a look. HiLo48 (talk) 03:26, 27 September 2010 (UTC)

substitution for lye water in a recipe

I'm trying to make homemade mooncakes and the recipe calls for 1 tsp lye water.....what disturbs me is that I have no idea what the concentration of such lye water would be. Is that 1 teaspoon 1M NaOH?

Most importantly, I don't really want to use lab-grade sodium hydroxide in my food.... is it possible to substitute with food-grade potassium carbonate solution? It's getting added to filling. John Riemann Soong (talk) 22:25, 22 September 2010 (UTC)

In On Food and Cooking it says that lye water is used in the manufacturing of pretzels as a 1% solution to help create the hard crust, but that sodium carbonate can be used instead. It must be being used only because it is alkaline so I'd guess that KCO3 would also be ok. Somebody here says you can find lye water in Chinese grocery stores, so that might be your best option. Smartse (talk) 23:18, 22 September 2010 (UTC)

Is that 1% by weight or molarity? John Riemann Soong (talk) 00:23, 23 September 2010 (UTC)

A percentage concentration almost always implies by weight per volume (w/v), see also percentage solution; molarity is never expressed as a percentage. TenOfAllTrades(talk) 01:28, 23 September 2010 (UTC)

Sometimes I see things like "5% acidity" in vinegar. John Riemann Soong (talk) 02:31, 23 September 2010 (UTC)

That means 5% (w/v) acetic acid. TenOfAllTrades(talk) 03:07, 23 September 2010 (UTC)

There is, however, such a thing as molar percent. -- 174.24.192.84 (talk) 05:13, 23 September 2010 (UTC)

Sodium carbonate can be made easily by heating a small amount of sodium bicarbonate in a pan. --Chemicalinterest (talk) 11:11, 23 September 2010 (UTC)

Solution? You can't seem to mean the powder. What replaces the proton? :S John Riemann Soong (talk) 14:12, 23 September 2010 (UTC)

Oh silly me, I think I see the reaction now. Another Na+ and the evolution of CO2. Pesky bidirectional multiple quilibria bicarbonates. Always throws me off in exams. John Riemann Soong (talk) 14:14, 23 September 2010 (UTC)

2 NaHCO₃ → Na₂CO₃ + CO₂ + H₂O --Chemicalinterest (talk) 11:12, 26 September 2010 (UTC)

Acid-base disproportionations are kind of interesting, where the same compound acts like an acid and a base. Note that the same really can't apply to water, at least not as a favourable reaction. Of course, maybe if water complexes gave off a gas when they combined... John Riemann Soong (talk) 17:30, 26 September 2010 (UTC)

Question about Einstein elevator and sensation of weight?

Suppose we have an elevator with a person stands on it's floor at ground level.

A- Let the whole unit starts accelerating upward exactly with 2g. It's net upward acceleration is g as the other g is canceling out the downward g.

B- Now after sometime, let the whole unit is stopped and dropped [may be upside down] with natural g from an appropriate height.

To me Weightlessness of an object [Zero gravity] is only possible if placed at the center and equidistance from the gravitating masses [equilibrium of forces] OR accelerating exactly at the same rate g of the gravitating mass but in opposite direction and in all other cases itt is under the influence of g or gravity force. Therefore I surmise that a person inside an elevator will not feel any sensation of his weight. I may be wrong but still doubt therefore I have the following

Questions:

So would the inside person in both flights feels his sensation of weight like stand on ground?

What direction would a person feels his sensation of weight force [equivalence principle] in Einstein elevator which accelerate exactly at same rate of g = 9.8 m/ s/ s in space?74.198.148.73 (talk) 23:48, 22 September 2010 (UTC) khattak#1

Edit: A- Let the whole unit starts accelerating upward with net earth gravity g at all times and behaves like Einstein elevator used for equivalence principle in space. Thus earth gravity g is cancel out at each point while accelerating upwards i.e. [2g upward - 1g downward = Net 1 g upward.]. The person is either hanging from the ceiling of elevator or from outside floor.

Thus to me, the condition of a person in both flight [accelarating upward and downward|] is same. —Preceding unsigned comment added by 74.198.148.78 (talk) 08:57, 23 September 2010 (UTC)

A - if the whole unit is accelerating upward at 2g, it is accelerating upward at 19.6 m.s^-2. Your suggestion about a net upward acceleration of one g is not correct. Dolphin (t) 23:57, 22 September 2010 (UTC)

(ec)You are confusing acceleration and force. If the elevator is accelerating up with 2g and with respect to a gravity field of 1g, it's accelerating with 2g (duh ;-), and anyone inside will feel 3g (2 from the acceleration, one from gravity). If the elevator is in free fall (i.e. "accelerating downward with g"), a person inside the elevator will not feel any gravitational force (until they hit the ground, of course). --Stephan Schulz (talk) 00:00, 23 September 2010 (UTC)

The experience of weightlessness doesn't imply the absence of gravity, but the absence of forces other than gravity. In other words if you were allowed to fall freely with gravity you would feel weightless (see for example Vomit Comet). If you stand on the ground, the ground acts on your feet with an upward normal force which is counteracting gravity and this is the weight you feel. In the elevator accelerating upwards, the upward force counteracting gravity is even stronger, and so you feel additional weight. Rckrone (talk) 00:13, 23 September 2010 (UTC)

When we are standing on the ground we don't accelerate downwards at 9.8 m.s^-2 because of the ground reaction force. When the ground reaction force acting on us falls to zero we say we feel weightless, not because our weight is zero but because the ground reaction force is zero. For example, when we dive or jump off a diving board our ground reaction force is zero and we feel weightless. Similarly, an astronaut in orbit or in the Vomit comet feels weightless because there is no ground reaction force. Dolphin (t) 00:18, 23 September 2010 (UTC)

... and, to answer your last question, - yes, an "elevator" or a spaceship accelerating at 9.8 m/s/s in free space (outside the obvious influence of any other mass) would appear to its residents to have "normal gravity" in the direction opposite to the acceleration. If they never looked out, they might believe that they were stationary on Earth. Dbfirs 05:53, 23 September 2010 (UTC)

September 23

volatile bases

I can sort of get (but not fully) why NaOH isn' simply a base analogue of HCl, looking at Fajans' rules. Why isn't for example, aluminum hydroxide volatile like HF is? Also is there any way to get an ammonium salt to distill as a complex ... I see that ammonium acetate decomposes rather than say form a cute NH4-OOCCH3 complex. (After all acetic acid distills as a dimer...) John Riemann Soong (talk) 03:08, 23 September 2010 (UTC)

I assume ammonium complexes don't distill because at high temperature you boil off NH3 (the complex is formed by a reversible equilibrium of stable components and LeChatelier says they are shifted by loss of a volatile component). In their salt forms, the boiling point is expected to be high due to intermolecular ionic attraction. That is, you can easily visualize a low-energy "decomposition" pathway. Salt complexes that don't dissociate upon boiling would require very unstable and/or nonvolatile components in order to keep "together" (e.g., BF₃•OEt₂) or no other "easy" reaction they could undergo with thermal activation energy. Ammonium chloride sublimates, but you have to reduce the pressure to allow that to happen. I assume that at the cooler temperatures where "→gas" transition occurs at lower pressure, the acid/base equilibrium is not as shifted based on volatility so you can evaporate the complex rather than dissociating it (T∆S term less important at low T). HF is actually less volatile than one might expect based on its low mol-wt and covalent structure with no unsatisfied octets. But "less volatile than extremely volatile" is still "pretty volatile" (it H-bonds intermolecularly just like your acetic acid dimer case). DMacks (talk) 13:49, 23 September 2010 (UTC)

standing waves

Does it completely not matter how two opposite waves are timed? I don't see anything in the equations for the difference in phase between two waves. If those waves (travelling in opposite directions) happened to be superimposed such that they always negated the other, wouldn't we get a string without vibration? I understand there's a trig identity that says otherwise, but conceptually I want to see why we get positions with invariant amplitude. John Riemann Soong (talk) 04:20, 23 September 2010 (UTC)

(Not sure if I totally understand the question.) The two waves only cancel out when they are lined up, but at the instant this happens the string still has non-zero velocity, which continues the motion. Once they pass through each other and become out of phase again the shape of the wave reappears. The relative timing of the two opposite waves is determined by the fact that each one is reflecting at the end of the string and becoming the other. That's why there will always be a node at each end, and why only certain resonant frequencies can exist on the string in a standing wave. Rckrone (talk) 05:02, 23 September 2010 (UTC)

I guess I want to ask another way. When waves are reflected at a frequency that is not a harmonic or a fundamental, what happens to all the energy that would normally be retained by a standing wave? John Riemann Soong (talk) 10:25, 23 September 2010 (UTC)

Other shaped waves can still live on the string in perpetuity (in the absence of friction), they just won't form a standing wave. Sort of as a side note, any shaped wave can be thought of as a sum of standing waves by taking the Fourier series. Rckrone (talk) 13:10, 23 September 2010 (UTC)

Yes, but the motion is damped somewhat. There is a resonance effect when you say oscillate a piece of string: the string doesn't budge very much unless there are standing waves.John Riemann Soong (talk) 14:10, 23 September 2010 (UTC)

In an experiment with a high-energy beam,

In an experiment with a high-energy beam, hydrogen atoms each weighing $1.67\times 10^{-24}g$ strike a target with a velocity of $2\times 10^{9}cms^{-1}$. If $10^{15}$ atoms arrive each second, and the target is a lump of brass of 500 g thermally insulated, find how long it will take for the temperature of the brass to rise by 100°C. (Specific heat of brass = $0.38JK^{-1}g^{-1}$115.178.29.142 (talk) 05:12, 23 September 2010 (UTC)

Sounds like a homework question. Think about conservation laws. Think about how you can estimate the incoming energy. John Riemann Soong (talk) 05:18, 23 September 2010 (UTC)

I figure the amount of energy required is $0.38*100*500=19000J$ but where does this energy come from? The kinetic energy of the hydrogens?115.178.29.142 (talk) 05:22, 23 September 2010 (UTC)

The question is not implying some sort of chemical reaction causing the brass to rise in temperature. So the only other source of energy is in the hydrogen stream which arrives with a high kinetic energy, and then is absorbed in the brass where it has almost no kinetic energy. Dolphin (t) 05:36, 23 September 2010 (UTC)

Do you remember how to find out the kinetic energy of a particle given its mass and its velocity? John Riemann Soong (talk) 09:15, 23 September 2010 (UTC)

Gelling time of methylcellulose

This is coming from a food perspective, not a laboratory perspective. Let us assume I have a solution of 5% methylcellulose in a liquid medium at 40 degrees C. I then add an equal amount of hot liquid at 80 degrees celsius to raise the temperature of the solution to 60 degrees, the gelling temperature of some types of methylcellulose.

How long will it take the new solution to gel? Is it instantaneous? One the order of seconds? Minutes? Thanks. → ROUX ₪ 19:55, 23 September 2010 (UTC)

Anyone? My google-fu is failing me, and there's a dish I'd like to use this concept in but do not have the resources for significant experimentation. → ROUX ₪ 21:24, 24 September 2010 (UTC)

Allow 10 to 15 minutes; during which time you continuously stir. The recipe presumable gives these temperatures as being right for the grade called for in the recipe to give the optimum hydration time, which gives plenty of time to thoroughly mix a large cauldron of the stuff without it going lumpy (see table on page two and there is some mixing guidence towards the end). When in doubt it helps to read the manufactures literature. If it's a DOW product you can double check by sending them an e-mail thats at the end of this information sheet:Product Selection Guide for METHOCEL Food Gums--Aspro (talk) 10:20, 25 September 2010 (UTC)

Close.. but not quite what I was asking. Let us assume as I said in my question that the methylcellulose is already hydrated and disperesed, it's just not hot enough to gel. → ROUX ₪ 16:58, 25 September 2010 (UTC)

Most common prescription drugs

Just out of curiosity, I'm trying (and failing so far) to find a list of the most commonly used prescription drugs in the USA. All I've found so far are vague groupings, like "anti-depressants", rather than the names of specific drugs. Since I'm not using this for professional research, if someone happens to know the numbers for Canada, UK, or some other wealthy nation, I'd be quite happy to see that, too. (Also, I'm aware that there's a unit-of-measurement problem, so I'll take whatever units you've got.) Thanks! --M@rēino 20:00, 23 September 2010 (UTC)

This would be a start for England. - Jarry1250 ^{[Who? Discuss.]} 20:43, 23 September 2010 (UTC)

Take a look here: http://drugtopics.modernmedicine.com/drugtopics/article/articleList.jsp?categoryId=7604 —Preceding unsigned comment added by 76.169.33.234 (talk) 05:49, 24 September 2010 (UTC)

Does Viagra require a prescription... Googlemeister (talk) 13:12, 24 September 2010 (UTC)

Thanks! --M@rēino 13:32, 24 September 2010 (UTC)

Resolved

I know you've marked this as resolved, but I wanted to point out that the lists on the modernmedicine site can be a tad misleading. It isn't taking into account that many popular medications are prescribed in combination with other medications. For example, there are many pills that contain a medication along with hydrochlorothiazide (hctz). The list shows how many times hctz has been prescribed by itself as one ranking. It shows each combination as a separate ranking. So, you don't see the total number of times hctz has been prescribed either by itself or in combination with other medications. -- kainaw™ 13:52, 24 September 2010 (UTC)

Anything left to discover after electricity?

The discovery and putting to work of electricity has revolutionised society, yet centuries ago was only known in relation to static electricity and lightning. Is electricity the end of the line, or are there other as yet little used phenomena that could potentially have as much as an impact as electricity? 92.15.8.96 (talk) 20:37, 23 September 2010 (UTC)

How would we know what we don't know? → ROUX ₪ 20:39, 23 September 2010 (UTC)

That was not the question. 92.15.8.96 (talk) 20:44, 23 September 2010 (UTC)

Well it was, actually. → ROUX ₪ 20:48, 23 September 2010 (UTC)

"...are there other as yet little used phenomena that could potentially have as much as an impact as electricity?" was the question. 92.15.8.96 (talk) 20:54, 23 September 2010 (UTC)

Lasers are making the transition from laser pen toys to useful technology at the moment, I'd say Chaosandwalls (talk) 21:11, 23 September 2010 (UTC)

Making the transition? Are CDs still fancy executive toys, then? Algebraist 21:14, 23 September 2010 (UTC)

Yes. WikiDao ☯ (talk) 21:51, 23 September 2010 (UTC)

I thought someone would mention quantum hocus-pocus, which I do not understand. 92.24.188.86 (talk) 22:45, 23 September 2010 (UTC)

Certainly Quantum computing looks promising, and is "still in its infancy". WikiDao ☯ (talk) 23:41, 23 September 2010 (UTC)

And there's plenty of mileage in materials science, from graphine to nanotechnology. Arguably we're right now taking what used to be known only in dead tree form and making it do new wonders on the internet. 3D printers look quite promising. None of these are quite the same as electricity, but all are in nascent states with the potential to be game changing. --Tagishsimon (talk) 23:50, 23 September 2010 (UTC)

Fusion would be pretty cool, too. WikiDao ☯ (talk) 01:50, 24 September 2010 (UTC)

Thomas Edison and Nikola Tesla, a fine pair of experimenters, thought that the Curie temperature of ferromagnetic materials could be used to make motors, but nothing was ever developed practically to exploit the phenomenon. If iron gets red hot, it is not attracted by a magnet. A small temperature variation up or down modulates the magnetic attraction. In a hot environment, this could be exploited to change temperature variation into force and work. Shield or expose the iron to heat, or turn electric current through it on and off, and you get work. Very steam-punk. In a shirt-sleeve environment, like on your desk top, the energy needed to get the iron heated close to its Curie temperature and to keep it that hot would swamp any work you could get out of the device. Around a blast furnace, or on Mercury or Venus, you might start out close to the Curie temperature. For neodymium-boron-iron the Curie temperature is around 300 C [9]. I recall that one of the aforementioned inventors took out patents in the 19th century for Curie motors, but did not reduce the idea to practice. Edison (talk) 04:45, 24 September 2010 (UTC)

I suppose anti-gravity would be quite useful for lifting heavy physics textbooks and such like. Sean.hoyland - talk 05:49, 24 September 2010 (UTC)

Some really speculative and revolutionising Physical phenomena would be time travel and faster than light communication but it is probably impossible. Using small black holes to convert mater to energy by Hawking radiation would be a big step. A more realistic step is High-temperature superconductivity at normal temperatures.

Some other more or less revolutionizing technological innovations that does not use new physics are artificial intelligence, a constructive prof that P=NP, nanotechnology, self-replicating machines, genetic engineering (Synthia ), cheep (space based?) solar power, space colonization (Dyson swarm), Tether propulsion, Brain–computer interface, Mind uploading, Cheap and efficient Closed loop life-support and life span extension.

Nuclear technology could also revolutionize the world much more than it has in both bad and good ways, a full-scale nuclear war would have a very big impact on the society. Many innovations we take for granted are still revolutionizing the third-world. In the long term there can of-curse be unknown Physical phenomena that will have great technological use. --Gr8xoz (talk) 06:29, 24 September 2010 (UTC)

The current increase in energy use is about 3% per year or 20 times in 100 years. If this continue we will need to colonize space before year 2400 since our energy use will exceed the solar energy hitting the earth. It will also exceed the radiative cooling capacity of earth.--Gr8xoz (talk) 06:47, 24 September 2010 (UTC)

Even when staying away from quantum mechanics, there are several phenomena and things that have been proposed as a future big thing. The main reason for this is probably that researchers must demonstrate a usefulness of their research to get grants. So in no particular order:

• Artificial diamonds are today only used in cutting tools and as coating on glass lenses. If the production of these take off, they could transform everything from computers to space elevators and kitchen utensils.
• Cymatics which is mostly a party trick today, could become important for assembling things in zero-gravity. [10]
• Lots of things animals do and make could become as widespread as plastics and microchips one day. for instance the goo of a snail: [11].
• Crosstalk is annoying in today's electronics, but is central to some amazing circuits that have been "evolved".
• The memristor exploits a non-standard effect in materials and could become a big thing in computing
• The random scattering of light and electric signals through a tangled mess of cables and materials was just that, until the random matrix results of Terence Tao, along with reservoir systems in machine learning showed very practical implications.
• The BZ reaction is another one of those science fair tricks, which hint at a whole field of science with all kinds of applications. This includes all kinds of self-assembling processes that creep and crawl around us every day but which we have so far not been able to mimick.

the list could go on and on. EverGreg (talk) 08:51, 24 September 2010 (UTC)

Away from physics, synthetic biology and protein engineering are very much in their infancy and it is difficult to know what they could achieve. David Wendell's photosynthetic foam hints at what may be possible in the future as biology and engineering combine. Smartse (talk) 11:12, 24 September 2010 (UTC)

Percentage of deaths from infectious diseases in New York

I was surprised to hear an American lady remarking on BBC radio that currently 9% of deaths in New York are due to infectious diseases. It seems like a big proportion, although far less than the 60% of a century or more ago. I never realised that modern city dwellers have a significant risk of catching a fatal disease off other people.

a) What diseases are these? b) How does this figure compare with other cities around the world, including for example London? Thanks 92.15.8.96 (talk) 20:43, 23 September 2010 (UTC)

Here's a link to the program in question, I was also a bit surprised by that stat. Between them infectious diseases must each have a small effect adding up to 9%. List of causes of death by rate has details from the World Health Organisation for the whole world and says that 23% of people worldwide die from infectious and parasitic diseases. I guess that influenza, tuberculosis and other lower respiratory tract infections and HIV must account for a considerable number. I guess that the Office of National Statistics will details about this in the UK somewhere, but in my experience their website is impossible to find anything on. Smartse (talk) 21:42, 23 September 2010 (UTC)

I found this which in Table 2 says that ~1% of people in the UK died of Chapter 1 infectious diseases and ~10% died from respiratory diseases, of which I assume many will be infectious since cancers are categorised as neoplasms. Table 2.1 lists the exact number of people who died of each disease. Maybe someone with more knowledge of the ICD-10 classifications can confirm this, but it looks to me as though the death rate due to infectious diseases is therefore probably similar in London as in New York. Smartse (talk) 22:00, 23 September 2010 (UTC)

(edit conflict) The U.S. CDC provides this list of causes of death, by U.S. state (2006). New York state is listed as having 3.3% of deaths caused by "influenza and pneumonia" alone, and there are some other infectious causes listed though I don't see it adding up to 9% (for the State; it seems about ball-park right for the city though maybe?). WikiDao ☯ (talk) 22:03, 23 September 2010 (UTC)

(ec) Here are the 2008 vital statistics for the city of New York. "Influenza and pneumonia" ranks very high, almost exclusively amongst the elderly, while HIV is pretty high amongst certain age groups. Tuberculosis has a negligible effect, interestingly enough. --Mr.98 (talk) 22:06, 23 September 2010 (UTC)

Looking at my numbers more closely, there were in 2008, in NYC, 54,193 deaths. Of these: Tuberculosis: 18; Viral hepatitis: 324; HIV: 1,073; "All other infective and parasitic diseases": 260; Influenza and pneumonia: 2,300. Total: 3,975, or 7.3%. So it's plausible that in 2009 or 2010 (so far) it could be up to 9% or so if the overall death rate dipped or the overall infection rate went up a tiny bit or both simultaneously. Also, I didn't count neoplasms because it wasn't clear to me how many of them were infectious, but if you include things like ovarian cancer or mouth cancers (which I believe some kinds are transmissible, right?) it bumps the number up to around 9-10%. --Mr.98 (talk) 00:31, 24 September 2010 (UTC)

Ovarian cancer is definitely not thought to be caused by infectious agents. You are probably thinking about cervical cancer and human papilloma virus. VERY different. Also, the majority of oral cancers are probably related to smoking and other tobacco use, although again HPV can be a risk factor. However, the death rate from these types of cancers is dwarfed by the other causes of death. --- Medical geneticist (talk) 13:02, 24 September 2010 (UTC)

Yes, indeed, that was what I was thinking of, hazily. --Mr.98 (talk) 14:03, 24 September 2010 (UTC)

I am not an expert on this but I believe that the final cause of death for very weak people such as very old persons often is an infectious disease, often they had died for other reasons very soon anyhow. --Gr8xoz (talk) 07:30, 24 September 2010 (UTC)

On the other hand elderly people sometimes get pneumonia and recover from it. 92.15.27.8 (talk) 22:34, 24 September 2010 (UTC)

Oripavin structure: wrong?

Hello.

I think the structure of oripavin has the CH3 bound to the phenolic OH not to the alchoholic as it is right now. I don't know if I'm right: the notes of my lecture says so and I don't have found any unique answer on the web.

Here is the link of the image: http://en.wikipedia.org/wiki/File:Oripavin.svg

I don't know how to edit and modify things, I just wanted to point out this small issue.

Thank you.

matitaccia

Posted on RD/M by Matitaccia (talk · contribs) 20:43, 23 September 2010, moved here by  Chzz  ►  20:50, 23 September 2010 (UTC)

The structures in the databases PubChem, KEGG, ChemID and ChemSpider all show the same structure as File:Oripavin.svg. --Leyo 21:02, 23 September 2010 (UTC)

The compound with no methyl on the lower-ring alcohol would not be stable...that enol would quickly change to a ketone form, with migration of the other alkene there to form an enone (in this case, the result is morphinone). DMacks (talk) 21:07, 23 September 2010 (UTC)

Okay, thanks for the answers. I'll change my notes then. :-) matitaccia —Preceding undated comment added 13:55, 24 September 2010 (UTC).

Right/Left Placement of Gas Tanks on Cars

Hey All!

Who decides on whether a car model's gas tank is on the right or left side of the vehicle? I would assume that the ratio of right:left should be kept somewhat even in order to make the most efficient use of pumps at gas stations. Is there some sort of regulatory system for this in the US or elsewhere?

Thanks! Tewner (talk) 21:28, 23 September 2010 (UTC)

Regarding gas station efficiency, tank side is irrelevant. Cars can pull through from either direction, allowing full use of pumps even if all the tank fills are exclusively on one side. As for who decides -- the design team. I don't believe there's any regulatory system for left/right (or rear, though this is increasingly deprecated) in the US, and I have no reason to expect one elsewhere. — Lomn 21:36, 23 September 2010 (UTC)

This must depend on locale. At most petrol stations I've been to, autos are expected to approach the pumps from a particular direction; doing otherwise would interfere with the queue. -- 58.147.60.48 (talk) 02:11, 24 September 2010 (UTC)

It would strike me, in an intuitive sense, that you'd want the tank to be on the same side as the driver, as it would make it a little bit easier to align the car up with the pump and not grind up against those concrete poles (which I have unfortunately done at least once!). But my general experience is that they can be on either side. The recent cars I have driven (all rentals) have had it on the left side almost exclusively, though. --Mr.98 (talk) 21:59, 23 September 2010 (UTC)

I know of nothing to suggest there is a design rule to ensure even distribution of left/right tank access among motor cars. I own a Toyota and a Mitsubishi, both right-hand drive. The Toyota has its tank access on the left, and the Mitsubishi on the right. Dolphin (t) 02:43, 24 September 2010 (UTC)

This question has come up before both here and at The Straight Dope. Dismas|^(talk) 03:08, 24 September 2010 (UTC)

The Mini Cooper in the 1960's, which enjoyed great success in the 1960's when driven by Paddy Hopkirk etc, had twin petrol-tanks - and I believe this was to help the balance in such a lightweight car. It became quite an identifying feature of this sportier mini, and some standard minis have been modified to have a fake second filler-cap.  Chzz  ►  03:15, 24 September 2010 (UTC)

Twin petrol-tanks would not help maintain good balance. If the contents of one tank is significantly different to the other you have a rolling moment. In contrast, the center of gravity of the contents of a single tank will never move much. Some British cars have two tank access points and I suspect they both lead to the same tank. Dolphin (t) 06:24, 24 September 2010 (UTC)

... (restored response strangely deleted? - perhaps through edit conflict?)..  :From a very limited experience of different cars in the UK, I have assumed that manufacturers place the fuel filler on the driver's side in the country of origin (of that manufacturer), but I don't have enough data to check whether my guess is correct. The actual tank is often central. Dbfirs 21:34, 23 September 2010 (UTC) Dbfirs 09:18, 24 September 2010 (UTC)

Yes probably [12] Nil Einne (talk) 10:09, 24 September 2010 (UTC)

In a couple of decades of driving in the UK, I have never once encountered a petrol pump whose hose could not easily reach a fuel filler on the far side of the car. 87.81.230.195 (talk) 16:43, 24 September 2010 (UTC)

Nor have I, but it does require careful positioning of the vehicle in some cases. Dbfirs 21:12, 24 September 2010 (UTC)

I disagree, maybe we have shorter hoses up north (no dirty innuendo please!) but in north east England I've sometimes pulled up to a pump on 'the wrong side' and then had to go to another pump after pulling the hose to its full length, despite being inches away from the pump and the filler (on the wrong side) being opposite the pump.Spoonfulsofsheep (talk) —Preceding undated comment added 21:44, 24 September 2010 (UTC).

I've had no problem in North-West England, with several different vehicles, but I agree that some fuel hoses are shorter than others, and only just reach, and then only if the vehicle is in exactly the correct position (filler lined up with hose). Sometimes it requires a considerable force to pull the hose fully out. Dbfirs 07:38, 25 September 2010 (UTC)

latex primer

what will happen if i just use a regular latex primer over melamine —Preceding unsigned comment added by Kj650 (talk • contribs) 21:57, 23 September 2010 (UTC)

My experience, from painting over formica, is that it will bubble and peel. If you rough-sand the surface before putting on primer, it will stick well. -- kainaw™ 02:12, 24 September 2010 (UTC)

Paint companies recommend a suitable primer be applied on a surface before your finish coat. Some websites recommend Kilz or Bullseye primer or special melamine primer [13] over melamine rather than latex primer. The primer's job is to adhere to the surface and provide a base for the finish coat. The finish coat's job is to be tough, look pretty and resist UV and abrasion. Edison (talk) 04:29, 24 September 2010 (UTC)

There are special paints for painting over laminate, melamine, etc. Get that and follow its directions for surface preparation. People like to then add several coats of polyurethane for toughness (again, follow instructions). PЄTЄRS J VЄСRUМВА ►TALK 16:59, 24 September 2010 (UTC)

Basic magnetism question

What makes unmagnetised steel attracted to both poles? Are there any equations? I need them really bad. Is it magnetic polarization -- the repelling poles move away and the attracting poles move closer? John Riemann Soong (talk) 22:59, 23 September 2010 (UTC)

In the near-contact limit (i.e. when the magnet is very close to the steel), the force will be of order $F={B^{2}A \over 2\mu _{0}}$ where B is the magnetic field intensity, A is the area of the contact surface, and the μ₀ is the permeability of free space. For real metals (as opposed to ideal ones) the actual force is usually somewhat less than this. Dragons flight (talk) 00:56, 24 September 2010 (UTC)

Ferromagnetic materials like steel comprise a large number of tiny bipolar magnets called magnetic domains, all aligned at random. When you bring the north pole of a permanent magnet close to a piece of unmagnetised steel some of the magnetic domains cease to be aligned at random and instead align so that their south poles face the north pole of the permanent magnet. (The opposite happens when you bring the south pole of a permanent magnet close to the unmagnetised steel.) The stronger the permanent magnet, and the closer the permanent magnet comes, the more magnetic domains are aligned by the permanent magnet so that the piece of unmagnetised steel progressively becomes a magnet. When the permanent magnet is taken away, most of the magnetic domains in the steel resume their random alignment so most of the magnetism disappears from the steel. However, there will be a small amount of residual magnetism due to magnetic hysteresis. Dolphin (t) 02:53, 24 September 2010 (UTC)

The force required to change the air-gap in a closed magnetic circuit is $F={\frac {1}{2}}J{\frac {d\phi }{dx}}$ where $d\phi$ is change in magnetic flux, dx is distance of the movement and J is the bond current or the current in the coil times the number of turns. Equations for some other cases can be found at Force between magnets, this article maybe should include the case with closed magnetic circuits.--Gr8xoz (talk) 07:22, 24 September 2010 (UTC)

September 24

How do autotransformers step up?

I'm still trying to wrap my head around this. As far as I can see, an autotransformer is no different to a potential divider or variable resistor (using inductors instead of resistors of course). I can see how voltage could be stepped down (using the potential divider effect), but how is it stepped up? If you inject the primary current halfway up the winding, how is it that the secondary side can be tapped off above the point where the primary current is injected? Surely you'll just get current flow in the top half of the winding, which would act as an inductor in series with the load? Zunaid 08:07, 24 September 2010 (UTC)

Do you understand how a normal transformer works?

All winding turns in a single phase transformer has (almost) the same magnetic flux Φ, the induced voltage in each winding turn is proportional to the rate of change of the flux dΦ/dt. If we assume no resistance the induced voltage in each winding turn will be U/Np, U is the applied voltage, Np is the number of turns in the primary winding. The dIp/dt will be adapted to induce the correct dΦ/dt in the core. Any coil on the core will have a induced voltage of dΦ/dt times the number of turns. The fact that voltage is applied to part of the coil does not change this.

Resistance causes voltage-drop in all winding turns proportional to the current in that winding, flux leakage cause differences in the induced voltage in different turns. The current needed to get the needed flux depends on the permeability and saturation of the magnetic core, eddy currents, currents in other windings and magnetic hysteresis.--Gr8xoz (talk) 08:55, 24 September 2010 (UTC)

"The fact that voltage is applied to part of the coil does not change this." WHY? If you only apply voltage halfway up the coil (with the bottom point grounded to complete the circuit) it makes logical sense to me that you'd only induce magnetic flux in the half of the coil that is part of the primary circuit. How the heck does the upper half get energised for you tap off a stepped-up secondary voltage? And yes, I should hope I know how a normal transformer works, else I'd be lousy at my job ;) It's just autotransformers that have me quite stumped. Zunaid 10:22, 24 September 2010 (UTC)

I do not want to offend you but I do not think you really understand how transformers work. It is exactly the same principle. I do not know what step you do not understand so I will try to point out some pitfalls, much of this will probably be obvious to you. As Yyy suggests you can think of an autotransformer as an ordinary transformer with the windings connected in series. In step up configuration the voltage across the secondary winding (high voltage output) is then added to the input voltage and forms a new even higher output voltage. The key thing to understand is that the same magnetic flux goes through every winding-turn on the same core and induces the same voltage in each. The different parts of the coil does not act as independent inductances see Inductive coupling. The magnetic flux in the part of the winding that are connected to the primary circuit goes through all the windings be course of geometry and that the permeability (magnetic conductivity) is much higher in the magnetic (iron) core than in air. The air acts as a (non ideal) insulator in the magnetic circuit.--Gr8xoz (talk) 11:28, 24 September 2010 (UTC)

I just want to point out that all ”understanding” in this area is relative, nobody understands why the physical laws are as they are. Inductance and magnetic forces can be explained by Relativistic_electromagnetism#The_origin_of_magnetic_forces but why there are electric interaction meditated by photons is to my knowledge unknown. I know that there are some pattern “symmetries” in the theory that suggests it but no explanation. Richard Fyenman talks about this in [14]. I hope I can help the OP (Zunaid) understand this in terms of how to apply known laws of nature but that does not “explain it”.--Gr8xoz (talk) 12:00, 24 September 2010 (UTC)

Autotransformer also could be similar to transformer with connected windings, which can step up. Lower voltage winding part of autotransformer acts both as low voltage winding and as part of high voltage winding. -Yyy (talk) 08:55, 24 September 2010 (UTC)

An ideal transformer

.

... an attempt to explain in different words.

As explained above, it doesn't matter whether the coils are separate (as in the ideal transformer on the right), or combined. It is the induced magnetic flux through the core that matters, and this flux extends through the core to energize the secondary coils. The analogy with resistors breaks down because the flux in the core provides the "driving force" for the output, not the applied EMF as in a potential divider. The circuit is not just two inductors in series, in fact it behaves as two separate circuits with a common ground. Dbfirs 12:31, 24 September 2010 (UTC)

.

.

To explain Yyy in other words - Another way of looking at an stepup-autotransformer is a normal isolating transformer with the secondary's low end connected to the primary's high end. If both have the same turn ratio (i.e. the transformer is centre-tapped), then when 100V AC (sin-wave) is applied to the primary another 100V AC is induced with the same phase on the secondary (assuming no loses). The voltages thus add up to the expected 200 V AC. CS Miller (talk) 12:51, 24 September 2010 (UTC)

Couldn't the questioner model an autotransformer as a 2 winding transformer with one winding of the primary jumpered to one winding of the secondary? Then if he/she understands how a transformer steps up or down voltage, he/she should understand how an autotransformer steps up/down voltage. It is a case of "buck" or "boost." Edison (talk) 03:19, 25 September 2010 (UTC)

Worst case for Nuclear Waste

If we assume complete lose of containment of all nuclear waste in the world, all of it is vaporized and evenly distributed in the atmosphere, what would be the consequences.

Of course the rate of cancer would increase but would we be able to live at earth at all?

I am against nuclear power because I think it increases the long-term risk of nuclear war but I think the risks with nuclear waste is often exaggerated so I would find it interesting to know a “worst case”. (The true worst case is of curse that all of it is ingested by humans but that is very unrealistic.)

I know that most of the waste is in ceramic form and will be very insoluble. The relatively low impact of over 500 atmospheric nuclear test indicates low impact but I don't know how to compare it to nuclear waste.

Of course I think we should store the nuclear waste as safe as possible in deep storages any way. --Gr8xoz (talk) 08:11, 24 September 2010 (UTC)

"(The true worst case is of curse that all of it is ingested by humans but that is very unrealistic.)"

Hmm, I can't help you with an answer, but I find your original scenario extremely unrealistic, unless governments all over the world did their best to contribute by spreading their nuclear waste into the air. -- Aeluwas (talk) 12:29, 24 September 2010 (UTC)

If all of the nuclear material in the Earth's crust were "vaporized and evenly distributed in the atmosphere", then we would all die, but, fortunately, loss of containment does not imply dispersal, so I agree with you and Aeluwas that your question is unrealistic. Our article on Radioactive waste gives lots of interesting facts, but doesn't answer your hypothetical question. It does emphasize that a lot of waste comes neither from weapons nor from power generation. Dbfirs 12:51, 24 September 2010 (UTC)

I know it is unrealistic, the worst I can think of is someone blowing up some of it with nuclear weapons. My goal is to get some baseline to calculate the global consequences of a smaller leakage. Say a leakage of 0.1 % in 100 years, take the radiation dose fore the baseline and multiply by 0.1% and the decay for 100 years and you get some upper limit for the global consequences. I know that it will not spread uniformly and that sedimentation and bioaccumulation will complicate things. Also if we build more nuclear power we can get 1000 times more nuclear waste than now or we can get less than now depending on the type of reactors and our need for energy.--Gr8xoz (talk) 13:00, 24 September 2010 (UTC)

As a matter of examining practical risks, it might be useful to look at the historical events listed at International Nuclear Event Scale as realistic worst-case scenarios. The Chernobyl disaster the Kyshtym disaster (the former involving a nuclear reactor, the latter involving a plant for reprocessing nuclear waste) are the only events in the topmost categories. In the United States, several facilities (including the Hanford Site and the Rocky Flats Plant) are responsible for past or ongoing releases of radioactive materials. There are ongoing lawsuits regarding individuals and populations exposed to contamination, however estimating the deaths which may or may not have resulted is extremely difficult.

Note that looking at the total and uniform vaporization and atmospheric distribution of all of the world's nuclear waste really isn't anything like a reasonable way to assess risk. Consider that each year, we product roughly sixty million tons of chlorine worldwide; that's enough to administer 20 pounds of the stuff to every man, woman, and child on Earth. Usually when stuff spills – be it nuclear waste or or red wine on a carpet – one observes one or more local hotspots of high contamination, surrounded by regions that are largely unaffected. If vapor is generated, or if waste enters flowing surface or ground water, you will often see a downwind plume of contamination. Instead of uniform distribution, one sees massive overkill caused by very high local concentrations, surrounded by regions of low or negligible contamination. TenOfAllTrades(talk) 13:47, 24 September 2010 (UTC)

I do not see the similarity with chlorine, if released in the atmosphere it would be to diluted to be toxic and since it is very reactive it will be very short lived. It could of curse be dangerous for a short time locally. Nuclear waste are rather long-lived and have time to spread for thousands of years. The decay of the nuclear waste is independent of its environment while chlorine reacts with the environment and become mostly harmless substances. The nuclear waste loses most of the radioactivity in the beginning and then the long-lived isotopes remains for a long time. Perhaps a release in the ocean is more realistic but I thought it was easier to compare the radioactivity with that of atmospheric testing since we know the average human dose received from that. Background radiation gives 0.15 mSv in 1963.--Gr8xoz (talk) 15:12, 24 September 2010 (UTC)

• If you'll indulge me in a bit of polemic, spraying the air with the waste product of the world's fission power plants isn't a very big deal. It's just uranium. If you really want to worry about us all dying from radiation, consider we've been injecting radioactive coal ash into the airstream for decades and then try to get a good night's sleep ever again. --M@rēino 13:52, 24 September 2010 (UTC)

It's not "just uranium." It's a load of fission products. They are much more radioactive than the isotopes found in coal. --Mr.98 (talk) 13:57, 24 September 2010 (UTC)

The scenario you are proposing is just not plausible. The real "worst-case scenarios" are pretty different — things like a terrorist crashing a 747 into a spent fuel site or a massive leak of a specific site occurring. (And the vast volume of nuclear waste is not in ceramic form, but in liquid form.) It's not really comparable to nuclear weapons testing, where a very small volume of material (by comparison) is vaporized and shot into the upper atmosphere (usually) where it can disperse/dilute. The result is a slight up-tick of certain types of cancers, spread amongst a very large population most of the time, only slightly differentiable from the background level. (Whether that is a good enough trade off for the security the nukes were thought to have brought was and is debatable.) By contrast, the worst-case waste scenarios are probably more like Chernobyl (high volumes of very nasty fission products being locally distributed), but even that is a very poor analog. In other words, the worst-case waste scenario is a massive contamination problem for a localized area, not an even distribution/dilution of contamination. --Mr.98 (talk) 13:57, 24 September 2010 (UTC)

Do you have a source that say that most nuclear waste is in liquid form, I think most of it (by radioactivity) is unprocessed used nuclear fuel. --Gr8xoz (talk) 14:50, 24 September 2010 (UTC)

Well obviously it depends on whether you are counting it in curies or in volume. I don't have numbers in front of me, but my understanding is that by volume, most of the high-level US waste by volume is military-derived, and most is in liquid form as a result of the reprocessing chemicals (stored at Hanford or Savannah River or other military tank farms). By curies, most is in the form of spent fuel, and is solid. Anyway, it all points to the further complications in this kind of discussion, as "nuclear waste" is actually a pretty broad category of different types of waste. --Mr.98 (talk) 22:51, 24 September 2010 (UTC)

Assume that someone does sneak into the Savannah River Site with a nuclear bomb. I chose this one because it is very large and shallow. It isn't buried under a couple miles of granite. If the nuclear waste was blown into the sky, it would be picked up by the wind. The wind blows from west-to-east. So, it would pretty much follow the Savannah River and settle along the land there. It would probably cause an increase in radioactive health issues in the area around Savannah, Hilton Head, and Beaufort. Then, it will hit the ocean. There is no reason to assume that any significant concentrations of radioactive waste will make it to Europe or Africa. You can easily run a scenario for other sites. For each, some planning went into deciding where to bury the waste. It wasn't just a bunch of monkeys looking for any old hole in the ground. -- kainaw™ 14:04, 24 September 2010 (UTC)

The weather effects are more complicated. With Savannah River you'd be worried about it being blow north, which is completely plausible on a local scale. The problem with your latter assumption is that Savannah River wasn't chosen because of its characteristics as a waste site, it was chosen for its characteristics as a place to have nuclear reactors. These are not necessarily the same characteristics at all — for example, being next to a river is great for a water-cooled reactor, but lousy from the point of view of burying waste. There are some overlaps, of course: the isolation of the site was chosen in part because of the possibility of meltdown. But none of the current DOE sites were chosen with terrorism in mind, which was a much later consideration. Most were chosen with the idea that the waste would be stored off-site, but that didn't work out. --Mr.98 (talk) 14:26, 24 September 2010 (UTC)

Bird

Hi. This bird (http://img707.imageshack.us/i/p9240001.jpg/) has entered in my room throught a window, and I have captured it. What is its species? how can I feed it? Thanks. emijrp (talk) 13:16, 24 September 2010 (UTC)

• Two questions: (1) what continent do you live on? (2) are you in the city (implying that this is a pet bird) or the country (implying that this is a wild bird)? --M@rēino 13:54, 24 September 2010 (UTC)

I'm from Spain, and yes, I live in a city. emijrp (talk) 14:15, 24 September 2010 (UTC)

i'm no expert, but it looks like someone in your neighbourhood has lost their parrotlet. EverGreg (talk) 14:02, 24 September 2010 (UTC)

I thought that because I dind't see this bird in the past in my city. I think that it can be an Agapornis. emijrp (talk) 14:15, 24 September 2010 (UTC)

I have released it. My parents don't want more pets at home (I have another bird). Thanks for your help. emijrp (talk) 14:15, 24 September 2010 (UTC)

Unknown White Powder

I have got some White powder, which has a bitter taste. On addition of water, it forms a white Suspension (chemistry) which tastes sweet. Effervescence is observed on addition of vinegar to the powder, resulting solution is soapy. What might it be ? —Preceding unsigned comment added by 119.157.63.194 (talk) 14:05, 24 September 2010 (UTC)

If this isn't homework, perhaps you'd better stop tasting it and adding random other substances to it until you find out (in a proper chemistry lab with proper precautions). If it is homework, we don't do that here, although we will tell you that vinegar in a homework question is just a codeword for its most famous ingredient (mentioned in the article you linked). --Tardis (talk) 14:21, 24 September 2010 (UTC)

I Just hope that it isn't a rookie in a drug testing lab! -- Q Chris (talk) 15:01, 24 September 2010 (UTC)

Hey now, chemists used to taste their products all the time. We wouldn't have discovered aspartame or many sweeteners if someone had not accidentally tasted them. But I don't see why something basic would taste sweet. Aspartame is a zwitterion, after all. John Riemann Soong (talk) 15:12, 24 September 2010 (UTC)

Also maybe its milk powder? If its nonfat dried milk, it wouldn't curdle but maybe bubble upon adding acid. Does the powder react with hydrogen peroxide or baking soda? Does it brown or foam when you add it to a hot frying pan? John Riemann Soong (talk) 15:20, 24 September 2010 (UTC)

Well, my mother accidentally tasted it, taking for Maida flour. —Preceding unsigned comment added by 119.157.74.205 (talk) 10:42, 25 September 2010 (UTC)

Melting point of water, hydrogen and Oxygen

Why is it that, even though Hydrogen and Oxygen have melting points in the -300's, that Water, which is comprised of hydrogen and Oxygen, melts at 32 degrees? Buggie111 (talk) 14:07, 24 September 2010 (UTC)

Because water molecules are asymmetric and so they tend to catch on one another, whereas H₂ and O₂ are homonuclear diatomic molecules, so they act more like smooth ellipsoids and slide past one another (that is, melt) more easily. --Tardis (talk) 14:15, 24 September 2010 (UTC)

Is this some weird code for hydrogen bonding? Weird-shaped isobutane is less symmetric than say n-butane, and in fact has a lower BP cuz of its weird shape. John Riemann Soong (talk) 15:16, 24 September 2010 (UTC)

Yes, it is — I didn't want to assume that the OP would find that discussion useful. Both fish hooks and tippe tops are asymmetric; perhaps I should have said "asymmetric in a way that causes them to catch". --Tardis (talk) 15:25, 24 September 2010 (UTC)

Is isobutane really less symmetric? Considering just the carbon skeleton, it's got a permanent C3 axis. The only guarantee for n-butane is C2; there may be others (additional C2, one or two mirror planes, a point-inversion) but only in specific conformations. Hard to make a definitive statement about "more" if the things you are comparing aren't the same (operators) and can change. DMacks (talk) 16:16, 24 September 2010 (UTC)

I really meant to say isopentane. John Riemann Soong (talk) 19:58, 24 September 2010 (UTC)

I think the OP is also missing a very important distinction. Hydrogen and Oxygen have different properties from Water because water is not a mixture of hydrogen and oxygen, it is a chemical compound containing hydrogen and oxygen atoms. Asking why water has such different properties than hydrogen and/or oxygen is akin to asking why you can't just take steel and rubber and glass and throw it into a pile and expect to drive it down the road. Though cars are made of steel and rubber and glass, it is how they are put together that makes it a car. Likewise, though water is composed of hydrogen and oxygen atoms, it is how the hydrogen and oxygen atoms are put together that determines the properties of water. They are put together differently than you would find in a simple mixture of hydrogen and oxygen. --Jayron32 02:55, 25 September 2010 (UTC)

Brown coating(?) that has ruined aluminum parts

There are some radiators (earth moving equip) made of aluminum that have turned brown. They are no longer weldable and do not attract magnets. An acid wash (Hydrofluoric acid and Sulfuric acid) had no effect. Lab analysis identified aluminum sulfate. Is this removable or has the metal been altered on a molecular level?--74.2.87.75 (talk) 15:18, 24 September 2010 (UTC)

Our aluminum sulfate article indicates that it will dissolve in neutral or slightly alkaline water, so an acid wash might have been the wrong choice. The article also says that it decomposes when heated above 580 C. Looie496 (talk) 15:57, 24 September 2010 (UTC)

Aluminum pans in the dishwasher

I've washed some nice, supposedly-dishwasher-safe, aluminum cake pans in the dishwasher with Cascade (detergent) and now the pans appear to have a sort of uneven white coating on them. It looks as though someone has coated the pans with flour, though the pans remain perfectly smooth to the touch. What chemical reaction occurred? Comet Tuttle (talk) 15:36, 24 September 2010 (UTC)

http://www.nytimes.com/2010/09/19/science/earth/19clean.html --Sean 16:15, 24 September 2010 (UTC)

No, that's not it - this was indeed presumably the low-phosphate Cascade, but this is a definite uneven change in the color of the pans themselves. The pans are perfectly clean, just discolored. It's not an issue of the low-phosphate dishwashing detergent doing a bad job of cleaning the surfaces. Comet Tuttle (talk) 16:50, 24 September 2010 (UTC)

I've run into this before with aluminum pans that are cleaned in contact with iron or steel pans. I am 99% certain that the contact between the iron/steel and the aluminum causes the creation of an electrochemical cell, with the highly-reactive aluminum acting as a Sacrificial anode. Electrochemically speaking, Aluminum is a very reactive metal; however it usually forms a very thin and impervious coating of aluminum oxide which prevent further corroding, thus aluminum gives the appearance of being inert. It isn't; its just protected by its own corrosion product. However, if it is in contact with iron in a wet, salty environment (like a dishwasher) you can create corrosion by setting up an electrochemical cell, essentially the iron acts as the cathode and the aluminum acts as the anode, and because of the big difference in electrochemical potential between the metals, this can rapidly corrode the aluminum. I have rendered unusuable some very good aluminum pots and utensils in this way, as they become coated with a fine grey powder which resists being cleaned off, but rubs off onto everything, like fingers and food. Ick. Now, I am careful to avoid putting aluminum into my dishwasher. If you are very careful to avoid contact with any other metal, you could still wash it in a dishwasher, but I have found its not worth the risk. --Jayron32 02:48, 25 September 2010 (UTC)

What disease would cause someone not to be able to eat corn?

I met somebody who said that they can't eat corn due to some disease, but I don't remember the name of the disease. Does anyone know what it might be? —Preceding unsigned comment added by A Quest For Knowledge (talk • contribs) 16:14, 24 September 2010 (UTC)

Sorry, we can't answer medical questions that call for a diagnosis. Just ask the person, perhaps? --Sean 16:18, 24 September 2010 (UTC)

(edit conflict with TotoBaggins twice) By "corn", do you mean Maize? Our article has a short section about a possible allergy, but says that it's rare, and not well studied: Maize#Allergy. Buddy431 (talk) 16:22, 24 September 2010 (UTC)

OP is not asking for a diagnosis but to be reminded of it's name. Depend what you mean by 'corn.' If you mean by 'corn' the cereal, than it might have been Coeliac disease.--Aspro (talk) 16:31, 24 September 2010 (UTC)

Celiac disease is an inability to digest gluten. Corn--maize--does not contain gluten. → ROUX ₪ 16:36, 24 September 2010 (UTC)

But lots of other corns do. DuncanHill (talk) 16:42, 24 September 2010 (UTC)

I don't see this as a request for medical advice, so I don't see any problem in answering it. Unfortunately I don't know the answer, though. It used to be thought that people with diverticulitis should avoid corn, but apparently the usefulness of that has been disproved. Allergies are always a possibility. Looie496 (talk) 16:32, 24 September 2010 (UTC)

(Edit Conflicts) I don't think this query qualifies as a request for a diagnosis or medical advice. The Querant clearly doesn't imply that he/she thinks he/she might have the disorder, nor is he/she asking on behalf of a third party, he/she is merely seeking information on a physiological topic prompted by a past encounter.

If the original locutor meant 'corn' in the broad sense of cereal grains, the the Gluten article and the links from it to Gluten sensitivity and Gluten-free diet might be relevant. 87.81.230.195 (talk) 16:33, 24 September 2010 (UTC)

You might be thinking of Eosinophilic esophagitis, symptomatic of allergic reactions to cow's milk, soy, egg, fish and wheat, but can also include corn and all products derived from corn (sugars, corn syrup,...). PЄTЄRS J VЄСRUМВА ►TALK 16:51, 24 September 2010 (UTC)

To the original poster: The confusion above is because the word corn means different things in different countries, so it's not 100% clear which "corn" you are asking about. In America, corn always means maize, whereas in England, it means, as noted here, "some local cereal grain, like maybe wheat or barley". To Sean: This is not a medical advice question. It's fine. Comet Tuttle (talk) 16:54, 24 September 2010 (UTC)

Sorry, I'm an American so yes, I meant Maize. If it helps, this came up in casual conversation as we were about to watch a movie. She said she couldn't eat popcorn because she had some disease. I asked her if she could eat corn on the cobb[15] and she said no. I asked her if she had it all her life and she said no. It might be coeliac disease. I know it wasn't a long name, like "muscular dystrophy" and "adrenoleukodystrophy". A Quest For Knowledge (talk) 17:05, 24 September 2010 (UTC)

It is not c(o)eliac disease, as corn does not contain gluten/gliadin. → ROUX ₪ 17:10, 24 September 2010 (UTC)

Hmmm...well, here's some more information I can provide. We've gone to dinner a few times and this was the only time she mentioned anything about any food issues. I know that she can eat cheeseburgers, french fries, chicken quesadillas and pepperoni pizza. Does that help? A Quest For Knowledge (talk) 17:20, 24 September 2010 (UTC)

You might want to consider upping the restaurants you go to with female companions ;-) --Stephan Schulz (talk) 13:13, 25 September 2010 (UTC)

Well, it's not all that uncommon to be allergic to corn. You can be allergic to corn but not wheat, or vice versa. I don't know what disease name she would have given you, though, other than "allergy", which you probably would have remembered. --Trovatore (talk) 17:24, 24 September 2010 (UTC)

(edit conflict)Yes, it confirms that despite what people have said above, it cannot be celiac unless she was ordering gluten-free cheeseburger buns and pizza dough. I'm also intrigued by the fact that she can eat quesadillas--were the tortillas flour- or corn-based? If the tortillas were corn-based, then I strongly suspect she has no such disease and merely dislikes corn or had a poor reaction to corn at one point. Many people, especially dining in restaurants, will claim disease or allergy when in reality they simply do not like a particular ingredient. By doing so, they ensure that people won't attempt to get them to eat it. Corn, however, can be an allergen (so can anything really). That being said, my understanding is that it is not a common allergen, and given the prevalence of corn and corn derivatives in everything in North America, such an allergy would make eating anything other than from-scratch home cooking very difficult. (For example, those cheeseburgers? The buns probably contained corn derivatives in the form of corn syrup, and the processed cheese almost certainly contained maltodextrin, a starch derived from both corn and tapioca). One website claims that when trying to recover from candida one should avoid corn. Then again, one should according to them also avoid anything wheat-based, which would knock out the cheeseburgers at least. Some doctors seem to claim that corn should be avoided for diverticulosis, but apparently there is no support in the literature for that. The only thing that I can find, and is borne out by anecdotal experience with an ex, is corn possibly exacerbating the symptoms of Crohn's disease or IBD. Note I am not a doctor. I am a chef, however, which does mean I have a pretty serious interest in food allergies and intolerances. → ROUX ₪ 17:37, 24 September 2010 (UTC)

I think you really need to ask her again. Food sensitivities are a very easy thing to get garbled. From here on we would just be guessing. She may be referring to a condition set off by the sensitivity and they are very numerous indeed. --Aspro (talk) 17:43, 24 September 2010 (UTC)

Well, I'd like to give her the impression that I'm a good listener. ;) Anyway, I don't recall if the tortillas were corn or flour based, but I think I might remember her asking about it. This happened before I knew about her not being able to eat corn, so I didn't think anything of it at the time. As Roux suggests, maybe it's Crohn's disease. A Quest For Knowledge (talk) 18:30, 24 September 2010 (UTC)

Or diverticulitis, but since you said it was not a long name, maybe colitis or crohns —Preceding unsigned comment added by 165.212.189.187 (talk) 18:59, 24 September 2010 (UTC)

Sigh. As I said above, there is nothing in the literature (according to meta-sites run by trusted orgs) to suggest that avoiding corn is particularly effective when dealing with diverticulitis. → ROUX ₪ 21:17, 24 September 2010 (UTC)

Sigh. But she could still be avoiding it because of her diverticulitis, whether or not the literature say it is effective. 109.155.33.219 (talk) 23:26, 24 September 2010 (UTC)

movement of a charged particle in an oppositely charged cloud

I have a uniformly charged cloud of some radius R of some charge +q, distributed infinitesimally over tiny particles, and a charged particle of -q released at rest on its surface. How do I model its movement? I think it will go straight into the centre and I know that the electric field inside this cloud is kqr/R^3. Acceleration of -q should be -kqr^2/(mR^3). But of course as the charged particle moves closer in, R changes and the electric field changes, so acceleration isn't constant so I can't use any kinematics. Any tips? John Riemann Soong (talk) 19:14, 24 September 2010 (UTC)

Wait this is effectively a harmonic oscillator isn't it? OMG. Velocity isn't zero at the centre. John Riemann Soong (talk) 19:36, 24 September 2010 (UTC)

Sounds similar to Wikipedia:Reference desk/Archives/Science/2008 November 19#What if we cut a hole through Earth?. That is gravity rather than electrostatics, but same concept and could steal the same basic math ideas from shell theorem. DMacks (talk) 19:40, 24 September 2010 (UTC)

Washing powders that produce fake dirt

I remember seeing on TV or hearing on radio long ago that washing powders and some other detergents are deliberately made to make the water they are in look dirty. Could anyone supply some more detail on this, the ingredients or chemistry involved? Thanks 92.15.27.8 (talk) 19:47, 24 September 2010 (UTC)

I have heard of this one. It is a conspiracy theory. Dolphin (t) 04:07, 25 September 2010 (UTC)

It also seems a it pointless. Unless there is some weird cultural thing in the UK (or whatever) I would expect most people put the powder and their clothes in the washing machine and turn it on and let it run. They don't periodicly check the water to see how dirty it is. Very often they won't look it at all. If they're evaluating a powder, they're likely to see how clean their clothes are, not how dirty the water looks Nil Einne (talk) 16:55, 25 September 2010 (UTC)

pupil dilation

Why do the chemicals that dilate people's pupils for an eye exam also cause very poor near vision for a few hours? Googlemeister (talk) 20:09, 24 September 2010 (UTC)

Depth of field;Aperture;Mydriasis;Tropicamide. --Aspro (talk) 20:18, 24 September 2010 (UTC)

Tropicamide lists this phenomenon as a side effect, but does not state why. Obviously mydrasis is what the drops cause, but the article does not itself describe the near vision effects. Googlemeister (talk) 20:48, 24 September 2010 (UTC)

The Ciliary muscle (which is what focuses the lens) is closely associated with the Iris dilator muscle and the Iris sphincter muscle (which are what control pupil aperture size). Chemicals like tropicamide are probably dilating the ciliary muscle, too, so that the lens can not be accommodated to focus on near objects. I'm guessing. WikiDao ☯ (talk) 21:17, 24 September 2010 (UTC)

That is why I started off with depth of field. If your camera with a prime 50mm lens focusses 30ft to 35ft there is not much perceptible change of image sharpness. Go macro (close up or near vision) and slight changes makes for so-much-change that you need to stop the lens right down in order to accommodate the whole image from front to back... Look at the images in the link from the desk/Miscellaneous: identify that thing [16] The object is only 2 inches across and yet it is all blurred (appeture wide open). Maybe the article ought to dot the i's and cross the t's. Now you have the background articles, do you think that you can expand it without further help?. --Aspro (talk) 21:26, 24 September 2010 (UTC)

No. hydnjo (talk) 23:47, 24 September 2010 (UTC)

When the aperture (your pupil) is very small, it's like a pinhole camera: not a lot of light comes in, but the place it hits on the sensor (your retina) depends only on which direction it was coming in from. If your pupils are dilated, a bit of light that hits a particular spot might have come from a number of places. (Imagine being very small and sitting on one spot in your retina and looking out the pupil: everything you can see is something that could have hit that point.) The rods and cones in your eye (just like the CCD or film in a camera) have no way to tell which direction light is coming from, only where it hit. So, the larger the pupil, the more blurriness; more light is coming in, but it's not as "organized". Paul (Stansifer) 02:18, 25 September 2010 (UTC)

Right. And that would be more the case for nearby things than for things far away. And there are probably also the lens issues mentioned above. WikiDao ☯ (talk) 02:39, 25 September 2010 (UTC)

Maybe also some Glare (vision) issues? WikiDao ☯ (talk) 23:51, 24 September 2010 (UTC)

How does this work? "low intensity pulsed ultra sound equipment has regrown dentin, pulp, gum, and density of mandible and maxilla bone"

This is quite a claim! From Low_intensity_pulsed_ultrasound - low intensity pulsed ultra sound equipment has regrown dentin, pulp, gum, and density of mandible and maxilla bone but the article doesn't say a word about the process itself...? The Masked Booby (talk) 21:56, 24 September 2010 (UTC)

Wow, that article sucks. There is quite an extensive medical literature on the topic, and that article doesn't mention any of it. Let me quote from the abstract of a recent review, PMID 18292369:

"When evaluated clinically, low-intensity pulsed ultrasound was shown to enhance bone repair (most commonly noted as a decrease in healing time), although variations in patient population hindered a definitive claim to clinical effectiveness. In vitro cellular evaluation and in vivo studies on animal models have revealed an increase in cell proliferation, protein synthesis, collagen synthesis, membrane permeability, integrin expression, and increased cytosolic Ca(2+) levels as well as other increased indicators of bone repair in response to low-intensity pulsed ultrasound exposure. Many of the cellular responses to low-intensity pulsed ultrasound mirror the cellular responses to fluid-induced shear flow, suggesting a link between the two as one potential mechanism of action. The considerable amount of information that has been revealed about the behavior of osteoblasts under low-intensity pulsed ultrasound exposure suggests that the exact mechanism of action is complex.".

Looie496 (talk) 22:26, 24 September 2010 (UTC)

September 25

Yellow jacket wasp, death of nest in winter

I understand that yellow jacket nests usually die in the winter.
How long does it have to be cold and what temperature is cold enough before I am reasonably sure the nest has died? I live in the Sierra Nevada foothills of California and am avoiding a certain valued trail because I am allergic. (Don't worry; I carry an EpiPen.) —Preceding unsigned comment added by Ahatch (talk • contribs) 01:12, 25 September 2010 (UTC)

Your friendly neighborhood Park Ranger or Forest Ranger would probably know or be happy to help you find out for your region and the wasps in question, even if the particular nest your are concerned about isn't in their exact area of operation. WikiDao ☯ (talk) 02:49, 25 September 2010 (UTC)

It's hard to find definite information, but the impression I get from looking around a bit is that yellowjackets can stay alive in their nests in temperatures down to freezing or even below, but they become pretty lethargic when the temperature drops into the 50's. Looie496 (talk) 04:37, 25 September 2010 (UTC)

Angular nodes and nodal planes

what is the difference between angular nodes and nodal planes?? are they the same?? the number of angular nodes in an orbital is equal to the azimuthal quantum number. and the number of nodal planes is also equal to azimuthal quantum number.. so, are they both same?? harish (talk) 03:06, 25 September 2010 (UTC)

I think that "angular node" and "nodal plane" are different nodes, though both are related to the principle AND azimuthal quantum number. If you look at File:HAtomOrbitals.png, you can see radial nodes and planar nodes. The radial nodes are apparent in the 2s, 3s, and 3p orbitals, while the planar nodes are apparent in the 2p, 3p, and 3d orbitals. I think that the term angular node refers to the spherically-shaped radial nodes which are concentric to the nucleus, while the nodal plane runs through the nucleus. My quantum chemistry knowledge in this area is about 12 years rusty at this point, however. --Jayron32 04:28, 25 September 2010 (UTC)

For an atom, an angular node and a nodal plane are the same thing. You usually say "angular node" if you want to distinguish them from "radial nodes". "Nodal plane" is more common when you're talking about bonding, so you often find it in introductory descriptions of atomic orbitals as well: a σ-bond has no nodal planes, a π-bond has one nodal plane and a δ-bond has two nodal planes. Physchim62 (talk) 08:37, 25 September 2010 (UTC)

Fire in Zero Gravity

Well the title is pretty self-explanatory, how would fire look, better yet behave in zeo-gravity, say, a space ship. 66.229.227.191 (talk) 12:19, 25 September 2010 (UTC)

Here you go http://www.youtube.com/watch?v=fuFftT6ZR4k ny156uk (talk) 12:23, 25 September 2010 (UTC)

That's a fairly long-winded video answer from a person in space who can't light a match due to safety rules. Here's a shorter video-answer http://www.youtube.com/watch?v=SZTl7oi05dQ - the cool concept here is that the flame forms a sphere since there's no gravity to cause the less-dense hot air to rise, but this results in smothering of the flame, because without convection no oxygen is brought in (e.g. from "below") to provide necessary reagents for continued combustion. -- Scray (talk) 14:14, 25 September 2010 (UTC)

(awesome video, by the way!) With the caution that since there isn't any convective transfer of heat away from the once-burning match, it will take some time to cool below its autoignition temperature. If a new supply of oxygen is introduced – either the hot object is moved to fresh air, or our astronaut stirs up the air by moving around the space ship or turning on a ventilation fan – the match will burst back into flame and burn until it again exhausts its local supply of oxygen. TenOfAllTrades(talk) 16:18, 25 September 2010 (UTC)

I want to increase the melting point of Butter.

I am on a vision to create a certain type of ghee (butter oil) which has a melting point approximately greater than 50 degrees Celsius (323 K) But natural ghee (butter oil) start melting normally at 30-32 degree celsius (room temperature). Can any one suggest me any chemical which can help me sort out the problem. Please specify the chemical name, its common name, chemical formula and its proportion to add in the natural ghee (butter oil) per kg. —Preceding unsigned comment added by Cma290193 (talk • contribs) 12:48, 25 September 2010 (UTC)

Hydrogen, along with a catalytic amount of Adams' catalyst: the exact quantities will need to be determined by experiment. Physchim62 (talk) 15:06, 25 September 2010 (UTC)

Does this sound like a homework question? WikiDao ☯ (talk) 17:16, 25 September 2010 (UTC)

You might not even need the hydrogen. The platinum catalyst alone may promote isomerization of the double bonds in the unsaturated fats, giving you trans fats that can have a higher melting point. Bromine might do the trick, too. I don't know if anyone has ever made the ghee-derived equivalent of brominated vegetable oil before. Maybe you could even patent the idea and make a lot of money by selling it to ADM. —Preceding unsigned comment added by 96.227.210.71 (talk) 16:32, 25 September 2010 (UTC)

Sauces with cornflour or wheat flour

When making a sauce, is there any advantage to using cornflour rather than wheat flour? Does cornflour cook more quickly, or have any other advantage? Thanks Edit: Cornflour is apparantly referred to as Corn starch in the former colonies. 92.28.241.137 (talk) 14:43, 25 September 2010 (UTC)

Yes, you use corn flour to thicken the sauce. The normal procedure is to wet the corn flour with a small amount of water or milk and then add it to the sauce near the end of the cooking: heating the mixture will cause it to gel, giving a thicker sauce. Wheat flour is usually used at the start of cooking a sauce, to adsorb fatty falvour components and stop them being lost. The two are not interchangeable: using corn flour instead of wheat flour will give you a lumpy suace (always a risk when you use corn flour), while using wheat flour instead of corn flour will give a sauce which is too liquid. Physchim62 (talk) 15:00, 25 September 2010 (UTC)

This sums it up better http://www.drgourmet.com/techniques/thickeningagents.shtml/thickeningagents.shtml--Aspro (talk) 15:25, 25 September 2010 (UTC)

(EC)Cornflour is much higher in starch than wheat flour, and doesn't contain gluten. The starch is the thickening agent, the same as is used in blancmange and custard powder. For a starch-thickened sauce or pudding, cornflour is generally what you want: you would have to add more wheat flour for the same effect, and that would come with more other components, like gluten. 109.155.33.219 (talk) 15:28, 25 September 2010 (UTC)

• Please disregard what the non-chefs are saying. Either corn or wheat flour will give you a lumpy sauce when used incorrectly; they must be fully hydrated in order to gelate the starch. The main advantage of corn flour over wheat is that it thickens more quickly, and does not render a sauce opaque when doing so. Both corn and wheat flours must be cooked, however, to remove the raw starch flavour. Wheat flour is not used to 'absorb fatty flavour components and stop them being lost;' it is used as a thickening agent via creation of a roux. The two are in fact largely interchangeable, and the notion that wheat flour will produce a sauce that is too liquid is, well, bizarre. It depends entirely on how much you use. Corn flour has the added advantage of not going 'gluey' as it cools. Essentially, you can use either one you like, it just depends on what you want your end result to be. → ROUX ₪ 17:17, 25 September 2010 (UTC)

Can you make water from Hydrogen & Oxygen?

Is it possible to take Hydrogen & Oxygen and turn them into water directly? E.g I have a tank of Hydrogen (gas or liquid) and a tank of Oxygen (gas or liquid) - is there a way to cause a reaction between them that will turn them to water (rather than a massive explosion!) Exxolon (talk) 16:06, 25 September 2010 (UTC)

All it takes is a spark to convert a mixture of H2 and O2 into H2O. Heat is generated. Whether or not you get a massive explosion or not will be determined by how much of the mixture you put a spark to. —Preceding unsigned comment added by 96.227.210.71 (talk) 16:10, 25 September 2010 (UTC)

You could do it with a hydrogen fuel cell. --Aspro (talk) 16:11, 25 September 2010 (UTC)

The name hydrogen actually means "water making" in Greek, and was named such because it was noted in the 18th century that burning hydrogen gas (with oxygen) produces water. --Mr.98 (talk) 16:17, 25 September 2010 (UTC)

Strictly speaking, the 'massive explosion' is the reaction that turns hydrogen and oxygen into water. As Aspro notes, hydrogen fuel cells separate the reagents and catalyze the formation of water, with the added bonus of extracting some usable electricity from the reaction. For a lower-tech solution, burn a mixture of oxygen and hydrogen under controlled-flow conditions. Oxyhydrogen flames are used in certain types of welding and glassblowing; one should be able to condense the water vapor from above the flame. TenOfAllTrades(talk) 16:37, 25 September 2010 (UTC)

Thanks for the answers. Schoolboy error, forgetting that the reaction already creates water vapour with the side effect of heat/explosion. I was looking for how to control the reaction, so if you were in space for instance with abundant supplies of both gases and wanted to safely create water for say terraforming purposes. Exxolon (talk) 16:40, 25 September 2010 (UTC)

The fuel cells of the Apollo Command/Service Module were designed to collect the water produced; the crew used this 'waste' from their fuel cells to supplement their onboard water supply. TenOfAllTrades(talk) 17:29, 25 September 2010 (UTC)

Video of the reaction WikiDao ☯ (talk) 17:24, 25 September 2010 (UTC)

Relativity

Why is Newtonian gravity incompatible with special relativity? I know it has to do with a simultaneous action, but does something acting simultaneously on something else lead to paradoxes in special relativity? 74.15.136.172 (talk) 18:46, 25 September 2010 (UTC)