Wikipedia:Reference desk/Archives/Science/2010 September 8

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September 8

Ancient bread

Surely bread before modern times was of the no-sugar-added, whole wheat variety? 67.243.7.245 (talk) 01:47, 8 September 2010 (UTC)

History of bread is where anything we have about it would likely be found. DMacks (talk) 01:56, 8 September 2010 (UTC)

As our article on flour says, refined flour first came into wide use in the 19th century. And before the 20th century, pretty much all bread used a starter or sponge rather than purified yeast, so no sugar was necessary to get the rise going. There were however types of bread that had sugar or honey added to sweeten them, dating back at least to the middle ages. Looie496 (talk) 04:06, 8 September 2010 (UTC)

The middle ages is a bit late in the game for sweet bread. There are sources from ancient Mesopotamia citing "sweet bread". 99.11.160.111 (talk) 06:39, 8 September 2010 (UTC)

As with my comment below, it seems unlikely to me all bread used a starter or sponge, as there was likely plenty of places where unleavened bread was uncommon, as there still is nowadays Nil Einne (talk) 09:29, 8 September 2010 (UTC)

It would seem rather unlikely to me that all ancient bread was 'whole wheat' considering not everywhere had much wheat yet it's likely some of these places had some form of bread Nil Einne (talk) 09:27, 8 September 2010 (UTC)

Following on from Nil Einne. Old European text often refer to the 'black bread' that the peasants' ate. Wheat has always been the most expensive cereal for bread, whereas black sourdough rye bread (made without yeast) was cheaper. History of bread appears to omit this nugget. Freeing the grain from the head of the wheat stalk was also labour intensive -especially 'spelt'. Modern verities are easier. --Aspro (talk) 12:48, 8 September 2010 (UTC)

I read that ancient bread probably had a load of other stuff like wool and straw and bits of wood, because they bulked it out to save the wheat. Quadrupedaldiprotodont (talk) 14:16, 8 September 2010 (UTC)

Note that crystallized cane sugar was described by Pedanius Dioscorides, who regarded it as a sort of honey. Wnt (talk) 15:00, 8 September 2010 (UTC)

Traditionally, bread was made with whatever was available. In a good harvest year in Britain, much more of the population would eat wheat bread, and the poorer might eat bread with barley or rye or oats mixed in. In average years, the reliance on hardier crops would be greater, and the poorest would be likely to eat bread with dried ground beans and peas mixed in. In bad years, the poor would be eating mostly oats and beans, and even the rich would have other corn mixed with their wheat. White bread was an aspirational food, and bolting (sieving through fabric) the flour for the finest bread was extremely time consuming and required finely woven fabric: even the rich only ate small manchet loaves, supplemented with coarser bread. Only the poorest ate the cheap, wholegrain loaves: other loaves were made from flour with more or less of the bran removed, and people used the bran for animal feed. 86.164.78.91 (talk) 18:03, 8 September 2010 (UTC)

Desert heat

I just moved to Phoenix from San Francisco. Needless to say it is much hotter here, the daily high has been over 100 F just about everyday (highest I have seen is 112 F) and it rarely gets bellow 85 F at night. I understand that the temperature effected by a number of factors, but it is the intensity of the sun that confuses me. I'm only four or five hundred miles further south, but the sun feels much much stronger, it is like standing under a heat lamp (In the middle of the day) and is nothing like the sun in the Bay Area. Are there other factors beyond latitude that effect the intensity of the sun? —Preceding unsigned comment added by Daniel J. Leivick (talk • contribs) 04:37, 8 September 2010

Air temperature has a profound effect on the sensation of heating from the sun. If the air is 90F the sun feels very intense. If the air is only 60F the sun feels much weaker, even though it is the same sun and you are at the same latitude. If the air is below, say 30F, the sun feels almost insignificant. Our skin is actually an inaccurate instrument for sensing the power of the sun (or any other radiant source.) The sensation of heating from the sun is dependent on the temperature of our skin. Dolphin (t) 05:33, 8 September 2010 (UTC)

Also, you'll get used to it after a while. Sean.hoyland - talk 05:44, 8 September 2010 (UTC)

There is a little information at Thermoception. Dolphin (t) 06:22, 8 September 2010 (UTC)

Thermoception is a word ? I did not know that. Marvelous. Sean.hoyland - talk 06:25, 8 September 2010 (UTC)

Large bodies of water (the Pacific Ocean in your case) help reduce the difference between day and night temperatures (and summer to winter). Also the oceanic gyres move the heat further up the coast. CS Miller (talk) 09:45, 8 September 2010 (UTC)

Thermoception relates to how you feel yourself affected (not "effected"!) by the ambient temperature. Cuddlyable3 (talk) 12:00, 8 September 2010 (UTC)

Thermal convection of the atmosphere is bringing moist air inland during the day (from the chilly seawaters off the SF coast). This air is no doubt, absorbing some of the heat rays (and rises in the process to be replaced by more cool moist air). The cooler air also help to take more of the heat away from the skin. On top of that, SF has a 1000 foot of extra atmosphere. Out of all the factors, I think it is the very low humidity days when I have noticed the heat lamp effect at the places I've been. Just a water mister can have quite an effect on the microclimate of the back yard. Does that seem plausible to you?--Aspro (talk) 13:20, 8 September 2010 (UTC)

Here in Barcelona, on the Mediterranean coast, the daily maximum temperatures in July are 4–5 °C (7–9 °F) lower than in Lleida, which is just a hundred miles inland (temperatures in Madrid, which is right in the middle of the Iberian peninsula, are similar to those in Lleida): that gives you some idea of the cooling effect of the sea in summer. The cooling effect for San Francisco is even greater, beacuse the currents in the Pacific off SF are cold: if we take the city of Murcia, which is the same latitude as SF and almost on the coast, the July average daily maximum is 28.4 °C (83 °F), as oposed to 20.1 °C (68.2 °F) in SF. Physchim62 (talk) 14:06, 8 September 2010 (UTC)

The effects of the Pacific Ocean are quite stark in San Francisco; I am surprised that someone who lived there never noticed the regular differences between San Francisco and the East Bay; on any given day it can be ten degrees or more hotter in Oakland than in San Francisco. Compare the climates in the articles. The average July high in Oakland is 72.7. In SF it is 68.2 Four degrees in average difference of temperature is pretty good for a few short miles. --Jayron32 02:07, 9 September 2010 (UTC)

The original question is not about air temperature as measured by a thermometer. It is about the perceived heating power of the sun. Daniel has written … it is the intensity of the sun that confuses me. … The sun feels much, much stronger. Dolphin (t) 04:10, 9 September 2010 (UTC)

AH. In that case, it's still a water issue, but likely an issue regarding water vapor in the air. Humid air has a higher specific heat than does dry air, water vapor itself having a relatively high specific heat (lower than liquid water, but higher than, say, nitrogen). That means that humid will tend to resist changes in temperature more than dry air; it also means that on a dry day the sun will feel hotter, since the air around you absorbs less of the heat energy , being of lower specific heat than on a humid day, with the temperatures being the same. This effect is not the same reason why a humid day in the shade feels hotter than a dry day; that is because when the air is closer to the saturation point, sweat evaporates less rapidly, providing less cooling. If we are specifically talking about the perceived heat of the direct sun in dry air vs. humid air, at identical temperatures, the difference is caused by the difference in specific heat of dry air vs. humid air. To sum up, humid air has a higher specific heat, so absorbs more heat energy before it gets to your skin. Dry air, of a lower specific heat, allows more of that energy to get to you faster. --Jayron32 04:36, 9 September 2010 (UTC)

humid air ... absorbs more heat energy before it gets to your skin No! Air is transparent and the solar radiation passes straight through. The sun doesn't heat the atmosphere directly. It heats the Earth's surface and then the surface heats the atmosphere by the process of convection. Close to the Earth's surface the air is warm but at progressively higher altitudes in the troposphere the air is progressively colder. Dolphin (t) 06:20, 9 September 2010 (UTC)

Nothing you said controadicted a single word of my answer, so using the word "No!" is inappropriate. Air is not at absolute zero temperature, so at some point it needs to absorb energy from something. The path it takes to get there is irrelevent, the heat capacity of humid air is still higher than the heat capacity of dry air. It's irrelevent whether that heat source comes from above, below, or the side. It still has a higher heat capacity. --Jayron32 03:34, 10 September 2010 (UTC)

Another thing that has come to me, is sitting in front of large bay windows, with the sun shining through on a very icy cold but very dry days. The heat lamp effect has been too much for me to remain sitting there. Found a simple graph of the sun spectrum and absorption ( in blue) and the transparent windows (yellow). The ESPERE Associaton. As you can see most of the long wave infra-red is absorbed by water vapour. Theory and experience seem to agree. So this would aply to cold dry deserts too.--Aspro (talk) 11:17, 9 September 2010 (UTC)

Thanks a lot for all the well thought out answers, but I'm still a little confused. We have a couple of possibilities as to what causes this "heat lamp" effect.

• 1. The air temperature is higher and increases the perceived intensity of the sun.
• 2. Lower humidity causes less infrared radiation to be absorbed increasing the intensity of the sun.

Of course could certainly be a combination of the two, but I wonder which has a greater impact. I have also experienced the bay window event Aspro was talking about. Which makes me lean towards option 2. On the other hand I don't think I can recall feeling the intensity of the sun outside on a cold but very dry day. --Leivick (talk) 23:22, 9 September 2010 (UTC)

Atmospheric carbon scenario difference projections on math desk

There was earlier ambiguity about whether this question should have been on the math desk or the science desk, but the way it is stated now, it is solely a probability density optimization problem (please correct me if I am wrong), so I copied it out on to the math desk. Why Other (talk) 05:42, 8 September 2010 (UTC)

Your question seeks a rational conclusion in economic policy making. It has human variables so it is not solely a mathematically soluble problem. Cuddlyable3 (talk) 11:55, 8 September 2010 (UTC)

de Broglie wavelength

Dear All,

Hello everybody,

1) how to find the de broglie wavelength of a 1 eV electron ?
2) how to find the momentum and energy of an X-ray with a wavelength of 0.5 A ? ( the A here with a bubble on top )

THANK YOU —Preceding unsigned comment added by Jameskiki (talk • contribs) 08:45, 8 September 2010 (UTC)

See De_Broglie_wavelength. Also, we won't do your homework for you. TomorrowTime (talk) 09:08, 8 September 2010 (UTC)

and see Angstrom and photon#Physical_properties 157.193.175.207 (talk) 09:10, 8 September 2010 (UTC)

For 2b, the relevant formulae are E=hf ; c=fλ      CS Miller (talk) 09:52, 8 September 2010 (UTC)

Bees - five eyes

Apart from the two large compound eyes, what is the purpose of the other three eyes? 92.28.242.240 (talk) 09:51, 8 September 2010 (UTC)

See Simple eyes in invertebrates. The ocelli seem to monitor general light levels rather than form images. So for example, in the case of Apis mellifera, if you paint over its ocelli it will start foraging later in the morning and finish earlier than foragers without covered ocelli and if it's cloudy they won't even leave the nest. It reduces their sensitivity to light by about 10x apparently. James and Carol Gould did some very nice experiments where they adjusted the light levels of a lamp (=fake sun) and when the light level reached a certain point the bees with painted over ocelli reoriented their waggle dances from oriented relative to the light source to oriented relative to gravity whereas the unpainted dancers carried on as usual. So they ended up using different dialects and workers trying to read the dances ended up going to the wrong locations. Sean.hoyland - talk 10:46, 8 September 2010 (UTC)

The article Evolution of the eye explains the origins of insect eyes that are so different from human eyes. This difference may be accounted for by the origins of eyes; in cephalopods they develop as an invagination of the head surface whereas in vertebrates they originate as an extension of the brain. Cuddlyable3 (talk) 11:43, 8 September 2010 (UTC)

Why do your muscles ache when you have the flu?

I have a flu and i also know one of the symptoms is aches and pains. I'm a (high school) biology student so i find this stuff rather interesting. We have done immunology but the teachers often tells us just simply something does happen without actually explaining how. I do some reading on my own but on a cursory glance i couldn't find much on this. Any insight would be greatly appreciated.

(I have also done endocrine and nervous system and protein synthesis if that helps to gauge my knowledge for the right response)

Kingpomba (talk) cheers kingpomba

See our article on influenza. The technical term for muscle aches and pains is myalgia (although that article doesn't really answer your question). Also, try this article for a general discussion about the mechanisms underlying many symptoms of viral infections. The take-home message from the article is that myalgia is the result of cytokine release. For example, tumor necrosis factor causes active breakdown of muscle protein in response to illness, probably as a mechanism to mobilize amino acids. There is also a role of prostaglandin E2 which can mediate pain by stimulating nerve endings. --- Medical geneticist (talk) 12:37, 8 September 2010 (UTC)

The body is under a lot of stress fighting the flu so everything else suffers as a result. Like a leaky pipe lowers pressure. Quadrupedaldiprotodont (talk) 14:13, 8 September 2010 (UTC)

The explanation I've heard (which may be specious, but is worth considering) is that one of the approaches the body uses to fight off viruses in raising body temperature, and muscular activity is one of the main sources for doing that. In extreme forms this produces shivers, but the body can also use muscular tension or sub-perceptible activity to achieve the same ends. Body aches, then, are the same kind of soreness one will get after any unaccustomed physical effort. --Ludwigs2 16:28, 8 September 2010 (UTC)

Neil Armstrong tie clip

My grandfather had a tie clip he claimed belonged to Neil Armstrong. He told me the tie clip was made from melting the legs of the lunar module down and all the astronauts got one. He told me it was registered. He passed away and I have it now and want to authenticate this. Any clues?

-Shari Morgan —Preceding unsigned comment added by 207.235.214.120 (talk) 12:49, 8 September 2010 (UTC)

The lunar modules were not melted down. The tie clips were made from the medallions that the astronauts wore. Each astronaut received one medallion, so they are very rare. What you would need to do is figure out how to explain why Neil Armstrong decided he didn't want to keep his. -- kainaw™ 12:57, 8 September 2010 (UTC)

NASA had a number of items made for presentation to VIPs and others as a goodwill gesture. We don't have such a photograph of one on Wikipedia. Can you photograph it and upload it to us or get someone else to please. It will likely have a serial number on it to prevent forgeries. Can you see any marks or numbers. Use a spy glass as there might be some minute letters to identify the stamping die. Any such serial number would be a start to establish a Provenance. Did your grandfather keep a diary in which he may have recorded the event? It is quite possible that it incorporates metal that came back from the voyage – but of course not the leg of lunar module --Aspro (talk) 13:58, 8 September 2010 (UTC)

The legs of the lunar modules were part of the descent stage, and were left on the moon (except for the LMs that never went to the moon in the first place) in order to save weight. Paul (Stansifer) 14:16, 8 September 2010 (UTC)

I agree that you should take a photo of it with any markings or numbers visible. Don't mean to be a spoil sport but no one else has said it yet, I think it's probably much more likely that it's not that at all. Stories tend to "build up" over time, even quite innocently and honestly, no one has to lie or be deceitful for it to happen. It's just human tendency to embellish stories over time as they are told and retold. We know that at least part of the story is not accurate (the bit about the melted down module legs), of course you would say "oh but it was something like that", unfortunately, once you add up all the it was something like that's you often end up with a completely different story. Of course I'm not saying it's not worth investigating, my argument does NOT rule out the possibility it was really Neil Armstrong's pin, and even if it wasn't it might still be something that makes a great heirloom. Vespine (talk) 01:28, 9 September 2010 (UTC)

Surely if anyone is going to be able to authenticate this it's NASA. I would suggest communicating with their Public Inquiries Office, being ready to send a photo if they ask for it. I won't post the email address here but you can easily find it with Google. --Anonymous, 03:50 UTC, September 9, 2010.

I detect some doubting Thomases out there, so I'll explain some more why I think this has a good chance of being from Armstrong. Nixon et. al. understood, that if you give out exclusive gifts to high profile people, who meet a lot of other high profile people, they will not be able to resist showing it off. In doing this, the gift 'announces' Hey, the US got to the Moon first! In other words, this was a PR exercise which was politically driven. It was grudgingly supported by NASA because they needed the tax-payers dollar -or rather several billion of them. Too much should not be read into the leg issue because astronauts have to repeat things so many times that they tend to sail through public functions on auto-pilot and frequently over simplify things. If the poster's grandfather was not an engineer this could easily lead to confusion. For instance: Armstrong could have mentioned that the next mission (Apollo 12) went on a little jaunt to retrieve bits from a Luna lander. What is there to distinguish this from the Luna lander modules or LM's. Amongst other things they removed were parts from its struts. The engineering name for leg is strut. I'm not saying this is what happened in this case but rather to show how lay people might get things confused by over simple explanations from a lunanaut who could well be suffering from jet lag. Also, although the lunanauts dumped much non essential equipment on the moon surface before leaving, they still brought back stuff that had no intrinsic scientific value -such as the moon rock boxes. Metal from such items gets regularly included in approved gift items ( unapproved ownership is illegal in the US) to give them a mystic. Therefore, it is quite possible that if the poster's grandfather did something in an official roll for Armstrong, when Armstrong was present in an official capacity, then Neil could have well given him one of the many tie clips that had been allotted to him. The probability can be higher than one at first imagines. A photo uploaded to here would be nice and we might be able to place it in an article. As an aside: The thought's gone through my mind as to whether there was ever a cover for the Apollo plaque on the LM leg. Could it have been inscribed with a eulogy in case it landed with far too much of a bump. This is something that they would have wanted to bring back if it existed. On the video I don't see them pulling a cord and a little curtain opening, so was the removal of such a cover what was meant by the phrase 'unveil the plaque'? --Aspro (talk) 12:52, 9 September 2010 (UTC)

I was hoping we'd at least get a photo. Given the lack of evidence, I'm going to stick to my doubting thomas theory. Vespine (talk) 23:47, 12 September 2010 (UTC)

hand

Explain http://j.imagehost.org/0021/213232.png —Preceding unsigned comment added by Mind345 (talk • contribs) 13:46, 8 September 2010 (UTC)

Dreadfully inaccurate drawing. I have yet to see a hand that actually folds that way. Also, next time show some manners. TomorrowTime (talk) 14:13, 8 September 2010 (UTC)

The questioner may be learning english. The grammar of asking questions is difficult. 92.15.20.52 (talk) 16:55, 8 September 2010 (UTC)

Is it? I don't quite agree with that, and I also don't think the word "please" is a terribly advanced one. At the very least, the inclusion of "please" would make this more of a question and less of an order. TomorrowTime (talk) 17:58, 8 September 2010 (UTC)

To illustrate what it may be like for the OP, how would you ask their question politely in Japanese or Korean? 92.15.3.53 (talk) 10:28, 9 September 2010 (UTC)

To someone raised with a different language and culture to you, it is not going to be obvious that 'please explain' is a polite question, while 'explain' is an order. Hell, I've seen Americans puzzled when they get slightly cold treatment, because they don't use certain 'polite' words as often as English people expect. I've seen and heard a lot of EAL students mangle questions in English, because forming them is not straightforward. Please try to extend courtesy to those who may be struggling. 86.164.78.91 (talk) 22:08, 8 September 2010 (UTC)

Oh yes, I ran into that in London, when I was browsing at a bookseller's display, and someone near me was smoking, and I wondered if he might be willing to move a bit. He scolded me for not saying "please". To my ear the word "please" would have been slightly offensive in that context, a sort of pseudo-politeness that masks what's really an order. --Trovatore (talk) 02:00, 9 September 2010 (UTC)

Erm, I was raised in a different language and culture, if by that you meant English. English is a foreign language to me. And assuming that non-English speakers have a hard time grasping such rudimentary concepts of the English language as the difference between orders and questions and words like "please" is, frankly, a little condescending. The OP is just being rude, plain and simple. TomorrowTime (talk) 23:10, 8 September 2010 (UTC)

But you have absolutely no idea whatsoever whether the person is or is not being intentionally rude. Someone thinking something is rude does not make it so. There is no evidence to support your conclusion so one wonders why you are answering questions on a science reference desk. Perhaps saying "show some manners" is rude too. It certainly seems rude to me given that "Explain" is about as concise as you can get. They didn't include a question mark. Many languages don't include an equivalent of please as part of a question, things get lost in translation and the world keeps turning. Even if the questioner is a native speaker of English there is no obligation on their part to conform to someone's unknowable personal model of acceptable human behavior in discourse. It doesn't say "Remember to add please to your question" or "Try to be Christian in your discourse" or "Please remember to add Insha'Allah to the end of your question" at the top of this page. There is however an obligation on our part to, as it says at the top of the page, "Be polite and assume good faith, especially with users new to Wikipedia" when we answer questions here. It would be lovely if everyone phrased their questions as "Would you be so kind to answer the following question" etc but it's not going to happen. Sean.hoyland - talk 03:01, 9 September 2010 (UTC)

I should add that my comment is in no way intended to discourage further culture clashes which are always welcome given their potential for hilarity. Sean.hoyland - talk 04:09, 9 September 2010 (UTC)

I suspect that he's asking "Why do the fingers have such dramatically different lengths when straight, but fold down to roughly the same level?"

If you look at your fist from the 'top' (ie: The business end of your fist.) you'll notice that the pinky bends a lot 'sooner'. Your fingers haven't changed length or anything, they've just all folded relative to their length so you can grab stuff easily.

I think I've explained that dreadfully, but the basic idea is that it's all in how they fold. There's no unexaplained paradox.

Did that answer your question? APL (talk) 14:53, 8 September 2010 (UTC)

In effect, the answer is "evolution". ←Baseball Bugs ^{What's up, Doc?} carrots→ 20:02, 8 September 2010 (UTC)

Saying that the answer is "evolution" is a bit vague, methinks. We might as well say that it's caused by "biology", or even "science". Without a specific elucidation of the selection pressures that favored the given outcome, "evolution" as the answer doesn't help the original poster much more than saying "magic". TenOfAllTrades(talk) 00:01, 9 September 2010 (UTC)

To get back on track, look at your own hand. You'll see the base of each finger is set at different heights, as are the tips, such that when folded into a grasp they all come down to the same level. I don't believe this is accidental - it likely has something to do with the most effect grasp, especially on tree branches where the entire hand must wrap around for grip. It would be interesting to see if all the grasping apes have this property. SamuelRiv (talk) 01:18, 9 September 2010 (UTC)

glue

i have a wood baseboard that it peeling off in 1 spot from moisture. what kind of glue should i use to secure it. is PVA glue strong enough? —Preceding unsigned comment added by Tomjohnson357 (talk • contribs) 16:12, 8 September 2010 (UTC)

I'm not sure what you mean by "baseboard", but PVA is unlikely to be strong enough, by quite a long way. Wood that is bending because of moisture (even thin sheets) usually needs to be replaced to give a repair that will last more than a few days. Physchim62 (talk) 16:17, 8 September 2010 (UTC)

baseboard = skirting board, although I cannot answer the question. 86.164.78.91 (talk) 17:41, 8 September 2010 (UTC)

I'd say you'd need nails, although I think it would be safer and more aesthetically pleasing to replace. —Preceding unsigned comment added by 178.167.223.93 (talk) 17:53, 8 September 2010 (UTC)

You can use No More Nails as a glue for bonding skirting board to walls - I do it. Though to be honest that's not your biggest issue - the issue you'll need to take action on is the Damp - it ain't really an ideal thing to have in a home (assuming it is skirting board you're interested in fixing). No more nails and its equivalents are very good - I remember a great advert for it when I was little of a chopped in half Mini glued to a bill-board to highlight the strength of the bond. ny156uk (talk) 21:43, 8 September 2010 (UTC)

what kind of glue is No More Nails? is it super glue? —Preceding unsigned comment added by Tomjohnson357 (talk • contribs) 21:54, 8 September 2010 (UTC)

I'm not sure - here it is on Amazon's website (http://www.amazon.co.uk/no-more-nails-DIY-Tools/s?ie=UTF8&rh=n%3A79903031%2Ck%3ANo%20More%20Nails&page=1) it's made by Unibond. Honestly i've never had any trouble with it and it bonds a very large number of materials. ny156uk (talk) 22:15, 8 September 2010 (UTC)

is it water proof? —Preceding unsigned comment added by Tomjohnson357 (talk • contribs) 22:56, 8 September 2010 (UTC)

It's a gap filling adhesive. Gripfix, Gripfill and Liquid Nails are all similar. It won't bond to damp or dusty surfaces. As ny156uk points out above, you need to sort out the source of the damp before you worry about re-fixing the timber. Trugster | Talk 18:11, 9 September 2010 (UTC)

... and it's certainly not strong enough for your purpose, though some use it for straight skirting-boards that are not under any sort of pressure. I agree that sorting out the damp is a priority, but, meanwhile, screwing the skirting-board back in place will be a better solution if you can get a firm fix into the damp wall. Dbfirs 13:46, 10 September 2010 (UTC)

successor representation

Could someone explain this psychological terminology for me? Thanks! —Preceding unsigned comment added by Chimonanthus-madder (talk • contribs) 16:50, 8 September 2010 (UTC)

It's a highly technical concept introduced by Peter Dayan as a way to improve the performance of a mathematical reinforcement learning algorithm. The paper that introduced it is available online here, but you will need extensive background knowledge to make sense of it. Where did you come across the term? Looie496 (talk) 17:39, 8 September 2010 (UTC)

Studying ice

Is there a name for the study of the cryosphere? Thanks, --The High Fin Sperm Whale 17:27, 8 September 2010 (UTC)

Glaciology, I think would be it. Looie496 (talk) 17:45, 8 September 2010 (UTC)

Glaciology is only about glaciers, cryology is used to describe the study of ice in general. Smartse (talk) 21:31, 8 September 2010 (UTC)

Wrong, and wronger. Looie496 (talk) 22:04, 8 September 2010 (UTC)

I don't really know but it's possible there might not be a field narrowly defined as "study of the cryosphere". Study of the planets is still just called planetary astronomy, so maybe it's something like arctic or polar climatology or something. Vespine (talk) 23:14, 8 September 2010 (UTC)

I agree. The American Geophysical Union, which would include many people that study the cryosphere, simply has the "Cryosphere Focus Group" that is charged with dealing with "Cyrosphere Science" or "Cryospheric Science". I also agree with the above that "Glaciology" is not broad enough to capture the entirety of the cryosphere. Dragons flight (talk) 03:53, 9 September 2010 (UTC)

Bolides

What exactly is a bolide? The section about it defines it very poorly. I always thought it was a rock that skipped off the atmosphere like a pebble on a pond. And how high up do they occur? --The High Fin Sperm Whale 18:24, 8 September 2010 (UTC)

I can't imagine what sort of answer you are expecting. Why do you think there is a better answer than the one the article gives? Looie496 (talk) 18:32, 8 September 2010 (UTC)

It can be summarized as "a really bright fireball." -- kainaw™ 19:00, 8 September 2010 (UTC)

The answer is the IAU does not specify what constitutes a bolide, so it is not surprising that our article also poorly defines it. Googlemeister (talk) 19:27, 8 September 2010 (UTC)

So it's basically a very bright meteor? Then what is the name for a meteor the skips through the atmosphere? --The High Fin Sperm Whale 20:47, 8 September 2010 (UTC)

Earth-grazer. Rmhermen (talk) 22:26, 8 September 2010 (UTC)

But note that that term has another meaning, as you see from the fact that you linked to a disambiguation page. --Anonymous, 03:53 UTC, September 9, 2010.

As noted in the article, geologists have a different use of "bolide" that has nothing to do with fireballs. In their usage, a bolide is a large asteroid or comet that actually impacts the surface and creates a crater. In that context "bolide" is thus largely synonymous with "impactor". Dragons flight (talk) 17:42, 9 September 2010 (UTC)

why do we laugh when someone falls?

hi, why do we laugh when someone falls? —Preceding unsigned comment added by 122.164.221.178 (talk) 19:54, 8 September 2010 (UTC)

Check out Physical comedy and see where it takes you. ←Baseball Bugs ^{What's up, Doc?} carrots→ 19:59, 8 September 2010 (UTC)

I can't laugh at people hurting themselves badly. A lot of people can't.--178.167.223.93 (talk) 20:22, 8 September 2010 (UTC)

I do not laugh when people fall over. Its not at all funny. I'd be ashamed to laugh at someone else's distress. 92.15.30.158 (talk) 21:05, 12 September 2010 (UTC)

Perhaps this is why I never found America's Funniest Home Videos very entertaining. P. D. Cook ^{Talk to me!} 20:45, 8 September 2010 (UTC)

Well I can laugh at a lot of stuff like that. If someone falls into water or something. But if they smack their back on a concrete curb I flinch with disdust.--178.167.175.240 (talk) 22:29, 8 September 2010 (UTC)

Sometimes it is just amusing. If someone young and in good health slips on a condom on grass (I've seen it happen) then it's hilarious to me so long as there is no injury beyond slight bruising. If on the other hand an old woman falls and breaks her hip, it's not in the slightest bit amusing. Regards, --—Cyclonenim | Chat  21:35, 8 September 2010 (UTC)

A common quip is that comedy is tragedy plus distance (or time). So when Blackadder falls off of his horse (around the 00:50 mark), we can laugh without remorse, since we also know that he's not actually hurt. (And because Blackadder is a horrible fellow.) In any case slapstick is a pretty old form of comedy. I don't know if it is universal to all human cultures but I would not be surprised if it was — it is something everyone can relate to, grappling as we all always are with the damnable physical world. I'm not sure there's much more of a "scientific" answer available than this kind of speculation, though. --Mr.98 (talk) 22:51, 8 September 2010 (UTC)

A scene with neanderthals in the BBC series Walking with Cavemen makes the suggestion that physical comedy (choking and coughing up meat after eating too fast) was a type that could be very much appreciated by apes and humans, whereas more abstract jokes (A giraffe walks into a bar; the bartender says, "Why the long face?") would require an advanced mind like that of Homo sapiens. Here is a free article that talks about the evolution of humor. Very interesting question. SamuelRiv (talk) 01:23, 9 September 2010 (UTC)

You may also want to have a look at our "Schadenfreude" article, which discusses some studies that have looked into this particular phenomenon. Wikiscient (talk) 01:53, 9 September 2010 (UTC)

I have found that groups tend to laugh at individuals in pain, whereas individuals rarely laugh at another individual in pain. See Herd mentality Quadrupedaldiprotodont (talk) 14:19, 9 September 2010 (UTC)

Some have claimed that "if I fall on my ass, it is a tragedy, but if you fall on your ass it is a comedy." To me, the absence of serious injury is more important then whether it is you or I who suffers the incident. It seemed pretty funny to me when my feet flew out from under me on the icy front steps one morning and I landed on the sidewalk with no serious injury. Comedy, not tragedy. I once saw a man in a carwash in Michigan when the temperature was far below freezing. He put his money in the coin acceptor, and extended the washing wand at arms length above his car, waiting for the flow of high pressure hot soapy water to begin. He was standing on ice. When the water started squirting forcefully from the wash wand, Newton's Law sprang into action, as surely as if he were doing a space walk using a small jet to maneuver. The force moment created by the stream of water caused the man to rotate, worse than if he had slipped on ice, since after his feet left the ground as he started to fall the wand kept accelerating his rotation. He was literally upside down by the time his head hit the ground. Had he broken his neck and died, it would not have been funny. Rather he sprang up and looked around to see if anyone had witnessed his hyper-pratfall. In fact, it was hilarious, a real thigh-slapper, since he had a real-life fall equal to anything in the Three Stooges but experienced no apparent serious injury. Edison (talk) 03:30, 12 September 2010 (UTC)

Arsenic cyanide

Does arsenic form cations? Is the resulting arsenic cyanide more toxic than either arsenic or cyanide alone? --75.33.216.97 (talk) 20:43, 8 September 2010 (UTC)

Arsenic is known to form covalent bonds to cyanide (see for example Diphenylcyanoarsine), so you could presumably have something like As(CN)₅ as triphenylarsine but it would not really be a salt containing As⁵⁺ ions (as per the "arsenic cynanide" name you propose for a Group 5 element) in the way that NaCN is a salt of Na⁺. There are a bunch of arsenic-based chemical weapons, but they are not listed as acutely highly poisonous in their typical use (nor is even diphenylarsine described that way--sounds unline standard symptoms of either simple poison--organometallic compounds are neat!). DMacks (talk)

Googling on "arsenic cyanide" I found this link, from Nature in 1892, which refers to As(CN)₃ by that name. I don't know if there's a more contemporary nomenclature that calls it by a different name. (But in any case it would certainly not be triphenylarsine — I guess it could be tricyanoarsine or something.) --Trovatore (talk) 22:43, 8 September 2010 (UTC)

Ah dangit, that's what I get for posting without proofreading. Tricyanoarsine would be it per one standard naming scheme. It is CAS# 1115-98-6 , we don't seem to have a WP article on it. DMacks (talk) 22:49, 8 September 2010 (UTC)

Arsenic and cyanide poison you in different ways, so it's hard to say that one would be more poisonous than the other. It's a bit like asking if apples are healthier for you than oranges. Arsenic tends to be a fairly slow acting poison, wheras cyanide is quite quick in fatal doses, so I would guess that the cyanide would kill you first: but a lot depends on dose, mode of administration, individual sensitivity, etc. Physchim62 (talk) 23:51, 8 September 2010 (UTC)

Primary source of a wavelengths table

On X-ray_fluorescence there is a table of wavelengths that I want to use in a book. I need to know the PRIMARY SOURCE so I can obtain a copyright permission. That site has been updated recently, can the author tell me the source of the data? 71.23.85.98 (talk) 20:46, 8 September 2010 (UTC)

You'll need to ask User:LinguisticDemographer. He or she hasn't been terribly active lately (last edit back in April), but you might get a response on his/her talk page. Clarityfiend (talk) 21:10, 8 September 2010 (UTC)

This was the edit where he or she added the table, along with an acre of other stuff. Comet Tuttle (talk) 21:15, 8 September 2010 (UTC)

You can also use Moseley's law, which is the special case of the Rydberg formula, which is a simplification of a more thorough quantum mechanical treatment of emission spectral lines. These values should be easy to calculate and independently verify from the fundamental principle, using a simple spreadsheet or calculator. All you need is to understand the notation (e.g., K-alpha, see also, Siegbahn notation). And, you need the Rydberg constant, which is available on our article, with a citation, (and probably appears in any text book on spectroscopy or basic atomic physics / chemistry if you want to verify). Nimur (talk) 21:23, 8 September 2010 (UTC)

(In the US) You can't copyright a table of factual data see: Feist v. Rural, so you don't need permission. Ariel. (talk) 21:29, 8 September 2010 (UTC)

Actually, it looks like Wikipedia has a copyright problem here. The table that is quoted in X-ray_fluorescence is obviously a selection of the primary data that's available, but the selection criteria are neither clear nor objective. I would guess that the table has been copied from a manufacturer's handbook, in which case it's copyvio. Physchim62 (talk) 22:57, 8 September 2010 (UTC)

The most quoted source of primary X-ray data is NBS 14. This is technically under copyright (even though it is a U.S. government work) and so you need to ask NIST in order to make a commercial reproduction that doesn't fall under fair use. Physchim62 (talk) 23:07, 8 September 2010 (UTC)

yellow

is white PVA glue the same as yellow PVA glue ? —Preceding unsigned comment added by Tomjohnson357 (talk • contribs) 22:01, 8 September 2010 (UTC)

Oops sorry meant to say - read Carpenter's glue. ny156uk (talk) 22:38, 8 September 2010 (UTC)