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April 22

Caffeine in Nesquik

How much caffeine is there in a 16 oz bottle of Nestle Nesquick fat free chocolate milk? The label simply says "99% caffeine free" without giving a mg amount. Magog the Ogre (talk) 00:32, 22 April 2012 (UTC)[reply]

I don't know the answer, but I'd like to take this moment to laugh out loud at the phrasing. Most of the drinks on this list have less than 1% caffeine by weight. One fluid ounce of water-based drink weighs approximately 30 grams, so anything listed there with less than 300 mg/fluid ounce will technically fit this description.-RunningOnBrains^(talk) 02:25, 22 April 2012 (UTC)[reply]

Ha! Good point! I wonder, does that phrase even have a legal meaning e.g. in the USA? Definitely <1% caffeine by weight is a low bar to cross :) SemanticMantis (talk) 03:25, 22 April 2012 (UTC)[reply]

Any amount higher than that should be fatal. Maybe the marketing department of Nestle can run with that and promote Nesquick with the slogan "It won't kill you." SkyMachine ⁽⁺⁺⁾ 08:17, 22 April 2012 (UTC)[reply]

"...at least not immediately." StuRat (talk) 13:47, 22 April 2012 (UTC) [reply]

This article appears from a google snippet to have the answer (it mentions chocolate Nesquik and has a table of caffeine content) but I don't have full access. By the way, the Nesquik company site makes the same claim for both the powder and the bottled drink. I am guessing that the "99% free" claim was merely transferred from the powdered product without any actual though being put into its meaning. One could deduce from that that the powder contains about 1% caffeine which will be diluted depending on how much milk it is mixed with. Spinning Spark 10:38, 22 April 2012 (UTC)[reply]

Flying car

Your proposed design has four fans each of radius 50 cm. Each fan sucks in air from above the car and blows it downward. The downward flow of air can be approximated as a column of radius equal to the radius of the fan traveling at uniform speed downwards.
A) How fast must the air be blown downwards if the car plus passangers weigh 1000 kg?
B) If the car is 100% efficient, how much power would it use while hovering?
The densidad of air is $1.2kgm^{-3}$

Is this the correct calculation for the upward force: $F={\frac {p}{t}}={\frac {mv}{t}}={\frac {n\pi r^{2}\rho hv}{t}}$ , and I think ${\frac {h}{t}}=v$ so $F=n\pi r^{2}\rho v^{2}$ . Overall I got $51ms^{-1}$ for part A and $2.5\times 10^{5}W$ for part B. Widener (talk) 08:25, 22 April 2012 (UTC)[reply]

Do your own homework. Whoop whoop pull up ^{Bitching Betty | Averted crashes} 17:50, 22 April 2012 (UTC)[reply]

The poster has done their homework. They have already shown an attempt at the question and are asking if they have made any errors. Spinning Spark 18:12, 22 April 2012 (UTC)[reply]

Your answers look correct. If this is for a calculus-based physics class, they're fairly certainly going to want you to work this out in terms of derivatives, i.e., start with F=dp/dt instead of F=p/t, but your equations work OK as long as you're careful about the definitions and assumptions being used. Red Act (talk) 01:19, 23 April 2012 (UTC)[reply]

For a general audience such as Wikipedia editors, please define each variable you use rather than just throwing out random Greek or Latin letters. Some readers took physics decades ago and the letters used might have been different. Few are likely enrolled in your particular class with access to your lectures, homework assignments and textbook.F=force?, t=time?, s=seconds?, mv=millivolts? What is nu?, What is rho?? Is h=Planck's constant? Meet us halfway. Edison (talk) 03:14, 23 April 2012 (UTC)[reply]

I wouldn't sweat this so much—the people who are likely to be able to assess this type of equation are probably fluent in the usual meanings of these symbols, and it's only important to define unusual or non-standard symbols. For basic physics formulas, F is always a force, p is always momentum, t is always time, m is always mass, v is always velocity, and ρ is always a density. h is generally either a height or Planck's constant; the correct choice should be obvious from context in nearly all circumstances (as it is here). There is no nu in the above equations; I'm guessing that you're (mis)reading the stylized v used in Wikipedia formulas.

There's no need to define standard SI units. ms^-1 is potentially ambiguous, as it could represent meters per second (m/s) or inverse milliseconds: (ms)^(-1); it may be best to write it as either m·s^-1 or m/s to emphasize that the m isn't a prefix. Not that it particularly matters in this situation, as the context clearly demands a velocity. W, finally, is always a watt.

If there are editors who aren't familiar with the notation used in these types of problems, I encourage them to ask—but there's no need to browbeat the OP. This usage would be familiar to any first-year undergraduate physics student. TenOfAllTrades(talk) 03:42, 23 April 2012 (UTC)[reply]

Perhaps to "any first year physics student" in recent years. "m is always mass" (except when it is "meters.") Right. There is probably a convenient listing somewhere in Wikipedia of today's common usages of Latin and Greek letters to represent things in science. A link to it would be appreciated. I have seen different textbooks use different conventions than those you cited, although I grant that there might be more standardization today than there was many years ago. Edison (talk) 17:53, 24 April 2012 (UTC)[reply]

At long last I found List of common physics notations, which is helpful in figuring out what is intended in such a question as this. Even that list has "n" only as as "refractive index" or "principal quantum number", which do not seem likely candidates. Amount of substance seems more likely. Would it be appropriate to add the latter meaning to the list of common physics notations, or would it have to go in nonexistent List of common chemistry notations? I Edison (talk) 17:20, 25 April 2012 (UTC)[reply]

Edison: italic m is mass, upright m is meters. Measurement units are written in upright letters. OP didn't get this right. – b_jonas 09:48, 26 April 2012 (UTC)[reply]

High buoyancy and low drag

If you build a very large capsule (hence with enormous buoyancy) but with a narrow pointed shap (hence very low drag), could you get this capsule to rise so fast it could actually rise up a waterfall?

According to my calculations, I see no reason why this could not be done. I calculate the terminal velocity as $v={\sqrt {\frac {2Vg(\rho _{w}-\rho _{c})}{C\rho _{w}A}}}$ . ( $\rho _{w}$ is the density of the water and $\rho _{c}$ is the density of the capsule). If you make ${\frac {V}{A}}$ sufficiently large then you can make $v$ as large as you want. If you can release it at any depth, then it can come as close to this terminal velocity as you want. Does anyone object to this? Widener (talk) 17:25, 22 April 2012 (UTC)[reply]

For a capsule in water, you cannot ignore parasitic drag, which increases linearly (IIRC) with total wet area. So your very aqua-dynamic capsule will still experience significant drag that is proportional to its volume. So in practical terms, I doubt it's possible. --Stephan Schulz (talk) 17:38, 22 April 2012 (UTC)[reply]

Oh I see, of course at high velocities the drag equation underestimates the true drag. Widener (talk) 17:47, 22 April 2012 (UTC)[reply]

I'm not much of a scientist, but I imagine that there aren't many waterfalls which are a column of solid water without any voids in them. As soon as your capsule finds some air, it's going to stop rising and fall out of the side of the waterfall. While I was typing that, I remembered that water with a lot of air bubbles in it (ie "whitewater") is a lot less bouyant than water without, so your caclations are going to go awry before you start. Good luck with your experiment. Alansplodge (talk) 01:14, 23 April 2012 (UTC)[reply]

You use hydrostatic pressure to calculate the buoyancy. It does not apply very well to falling water, whether it has air in it or not. Any vertical pressure gradient in the water would act against gravity and slow down the falling, but as far as I know waterfalls are close to free fall. --145.94.77.43 (talk) 05:06, 23 April 2012 (UTC) Though on a second reading I take you are planning to "jump" from a depth rather than starting at the base of the fall? --145.94.77.43 (talk) 05:12, 23 April 2012 (UTC)[reply]

There's a much more fundamental problem here than those discussed so far: bouyancy is driven entirely by the pressure gradient in a standing fluid. (It just happens that it can be stated simply in terms of density in that case.) In free fall, there is no such pressure variation (as the fluid is free to move around to suppress it) and bouyancy just doesn't happen. --Tardis (talk) 13:00, 23 April 2012 (UTC)[reply]

On rereading I see that this is fundamentally what 145.* already said. I should point out that an idealized cylinder of water falling through air will of course eventually reach a sort of terminal velocity where the shear from the air balances the acceleration due to gravity. There's no reason you can't (in principle) float up somewhat past this point before you reach too good an approximation to free fall to continue. --Tardis (talk) 13:11, 23 April 2012 (UTC)[reply]

Some Science questions

1)When the electric charge is quantized, how the quarks having fraction electric charge exists?

2)Why can't we use D.C. current everywhere? I mean, what if all the devices are also made to use dc. and a rectifier is added at each house.

3)Here is a practical problem.I have ammeter , 2 volt battery and a 2 volt dc rectifier. When i connect both voltage sources to ammeter why it shows different readings?V and R of ammeter is constant, so I must be constant according to Ohm's law.

For 1: Charge is still quantized, just maybe not in the size that was originally thought (i.e. quarks always have a charge that is a multiple of 1/3).

For 2: War of Currents. The problems are largely historical. There are some places with High-voltage direct current distribution. You could use DC current everywhere, but we don't, because it used to be unsuitable for long-distance distribution. Buddy431 (talk) 21:31, 22 April 2012 (UTC)[reply]

For number 3: How different? What are the actual readings for the battery and the rectifier? If we knew that, it would help answer the question. --Jayron32 22:01, 22 April 2012 (UTC)[reply]

This entirely depends on what the rectifier is being powered from. If it is the battery, a diode voltage drop would be expected at the output. Two volts is an unusual value for both batteries and rectifiers by the way. Also, you appear to be connecting the ammeter directly across the voltage sources. If this is so, there will be a significant volt drop at the source output and in general this will not be the same for both sources. Spinning Spark 22:10, 22 April 2012 (UTC)[reply]

There's something weird about the fractional electric charge. Quarks can't exist in combinations that have non-fractional charge, and can't transition in ways that would work out to an odd fraction. They go, say from 2/3 to -1/3, not 2/3 to 1/3, emitting W particles. This is sort of the way that electron spin can be +1/2 or -1/2, but the photons have to carry an angular momentum of just plain 1 (Planck's constant, that is). Not sure why things are that way at the bottom - is there a way to understand that intuitively? Wnt (talk) 00:50, 23 April 2012 (UTC)[reply]

For question 2: It is really simple to have an electric generation and distribution to serve a large area wherein the electricity is generated, then stepped up by simple transformers to a very high voltage AC at the generating station and sent in all directions, then stepped down to say 12 KV at substations every few miles, and distributed to a neighborhood, then stepped down to say 120 or 240 volts (depending on the country) by a transformer every block or so, to be sent into houses. With DC, the generating stations would have to be every 2 miles or so apart, producing 120 (or 240) volts, because of "copper losses." The same power could be provided by DC, but much, much more copper would be required. Copper currently costs close to 4$ (US) per pound. Edison (talk) 03:09, 23 April 2012 (UTC)[reply]
It makes me kind of uneasy that AC power is being advocated here by Edison, of all people. —Akrabbim^talk 12:40, 23 April 2012 (UTC)[reply]

Ha! DMacks (talk) 15:22, 23 April 2012 (UTC)[reply]

So far as I know the War of Currents stuff is sort of out of date. As I recall HVDC is now a serious contender for very long range distribution networks, like proposed transmission from solar or wind stations in the Sahara to Europe. (Of course, as you can tell from the sound of an idea like that, it may be a little starry eyed) In former times, changing DC voltage from one value to another was difficult, making it easier to use high-voltage lines (less loss) with AC, but as I understand it this is no longer such an obstacle. Wnt (talk) 14:09, 23 April 2012 (UTC)[reply]

What can be done now that could not be done decades ago is the use of switchmode power convertors to change the voltage. Until the development of high power Field Effect Transistors, efficient low cost switch mode convertors (aka DC to DC convertors) could not be made. Until 30 years ago all power operated consumer electronics used transformers to bring the 120V or 240V house power down to whatever voltage was required internally - now virtually all consumer electronics uses switchmode. However, don't expect switchmode to be used in electricity substations and street distribution any time soon, as the reliability, while good enough for consumer products, is no where near that of a transformer, and not good enough for power companies. Transformers are also very tolerant of short term (<1 second or so) overload, which tends to be frequent in power distribution. Switchmode on even small overload must shut down to protect itself, whereas transformers even on 300% or more overload just keep on delivering close to the normal voltage, allowing fuses & circuit breakers to operate where necessary, with discrimination. Discrimination is the feature provided by a hierachial arrangment of fuses or circuit breakers that result in only the minimum of consumers suffer blackouts due to faults. Keit120.145.185.73 (talk) 14:34, 23 April 2012 (UTC)[reply]

Thanks for a really informative response. I put the link above into standard Wikilink format (hope you don't mind). Wnt (talk) 23:29, 23 April 2012 (UTC)[reply]

For question 2, some devices, such as AC motors, require AC. Of the devices that use DC internally, such as radios, televisions, and computers, they need different values of DC, so it has been easier to have one standard AC voltage and build transformer-rectifier units to step down to the DC voltage needed by an individual device. The evolution of cheap and efficient DC to DC converters is much more recent than most of the electrical infrastructure. Jc3s5h (talk) 14:22, 23 April 2012 (UTC)[reply]

For question 1, it's hard to give a definite answer because we don't really know why charge is quantized in the first place! However, there are a few lines of reasoning that may shed some light on it. Quarks, electrons, etc. are all part of the standard model of particle physics, which is built on certain fundamental ideas like symmetry (specifically, gauge symmetry). In order to have a working gauge theory, there must be an exact balance between certain properties of the different particles. In particular, there's something called a gauge anomaly that will completely break the theory if it doesn't balance out. And one of the things that needs to balance is the total charge of all the particles in one "generation." That means that the charge of (electron + neutrino + red up quark + red down quark + blue up quark + blue down quark + green up quark + green down quark) = 0. Since the each quark comes in three colors, its charge contributes three times. So you can say in a sense that quarks have multiples of 1/3 times the electron charge because three quarks have to balance against one electron. Of course, this is a hand-wave-y argument, and there's a lot that we still don't understand about this topic. --Amble (talk) 02:42, 26 April 2012 (UTC)[reply]

Cholera rates in Kenya

Hi Reference Desk,

I'm look for the prevalence of cholera in Kenya. I can find [rates], but nothing on cholera. Please help me. Wiki or external links that directly inform me of this information would be great! Thank you. 208.22.79.249 (talk) 23:15, 22 April 2012 (UTC)[reply]

There's some information at WHO: [1]. It lists the number of cases of Cholera for many countries, including Kenya. RudolfRed (talk) 00:32, 23 April 2012 (UTC)[reply]

The WHO also has a short article here. Someguy1221 (talk) 00:36, 23 April 2012 (UTC)[reply]

Thank you. If anyone else has anything, please help. -original poster 208.22.79.249 (talk) 04:11, 23 April 2012 (UTC)[reply]

April 23

Chemistry/Amylose and amylopectin Determination.

How can i determined amylose and amlopectine in starch sample. — Preceding unsigned comment added by 78.138.24.1 (talk) 10:19, 23 April 2012 (UTC)[reply]

Do your own homework. Whoop whoop pull up ^{Bitching Betty | Averted crashes} 10:23, 23 April 2012 (UTC)[reply]

The basic schoolchild test for amylose starch is given in the Wikipedia article. A test specific to amylopectin is trickier, and I haven't studied Chemistry for more years than I care to remember, so I'll leave it for someone else to comment of the appropriateness of formamide. Are you wanting to determine the relative proportions of the starches? Dbfirs 07:16, 24 April 2012 (UTC)[reply]

Kills 99 per cent of germs...

That's the claim of household bleaches and surface cleansers etc - but are they doing the same thing that antibiotics are doing? What of the one per cent of germs that survive? Are we breeding supergerms? Bleach-resistant e-coli? Chlorine-tolerant salmonella bacteria?

Ta

Adambrowne666 (talk) 11:34, 23 April 2012 (UTC) There is a major difference between antibiotics and bleach: the 1st is a bacteria-only poison, working by a very specific damage it deals to the bacteria protein making process. Without protein making on the run no living cell can, well, stay a living cell. It dies and eventually decompose or is eaten by a still-living cells. Bleach is a different thing altogether: it is a highly reactive compound. It reacts with the cell membrane, dissolving it. It reacts with many, many molecules inside the shattered cell, destroying anything and everything. It consumes the cell and it contents. From this it is clear that, unlike antibiotics, bleach is poison for every living cell, not just bacteria. Since bacteria does not live in a protective layer of dead skin as we do, contact with fairly low concentrations of bleach for several dozen minutes kills it. 109.65.9.22 (talk) 13:10, 23 April 2012 (UTC)[reply]

Bleach works in part by a specific mechanism, which is opposed by Hsp33 and EF-Tu. [2][3][4][5] Now it's loss of Hsp33 that makes a strain of cholera bacteria extra sensitive to bleach. I have not seen anything in NCBI about evolution of more bleach resistant bacteria, and it is possible that this is much harder because toxicity affects many different things, all of which would have to simultaneously evolve to overcome the problem. Nonetheless, until proven otherwise, my guess is that such bacteria can, will, and probably have evolved to develop greater bleach resistance, and that this adversely affects people when their own cells' attacks with oxidizing agents are better rebuffed. Wnt (talk) 13:59, 23 April 2012 (UTC)[reply]

I suspect the 99% business is a truth-in-advertising CYA to avoid charges of unreasonable claims, but bleach kills pretty much 100% of germs unless they're somehow shielded from contact with the bleach. Scratches in a surface, for instance, coverage by some other substance - grease, for instance, etc. would be a shield - and which could be seen to negate a 100% claim. The building contaminated by Reston virus was decontaminated (initially, anyway) by bleach heated in electric skillets. Acroterion (talk) 20:29, 23 April 2012 (UTC)[reply]

Quantum entanglement and kinetic energy

Let's say you have two particles that are entangled. If you impart kinetic energy to one particle, will kinetic energy be imparted to the other particle? ScienceApe (talk) 16:55, 23 April 2012 (UTC)[reply]

No. When you change the particle by adding energy (using some unspecified mechanism), its quantum mechanical energy state is no longer identical to its previous state, and therefore no longer identical to its pair partner. Rather, its state is "not necessarily identical," because even if you specify how you modify the energy, we don't know what you did to the quantum mechanical energy state until you measure it again, ad infinitum. Quantum mechanical entanglement sure becomes a lot less interesting, (insofar as it has no useful practical consequences), when it is treated correctly! Nimur (talk) 17:44, 23 April 2012 (UTC)[reply]

Female scientist question

Looking for the name of a Female scientist , who was a pioneer nd gave and lost life to science. She was homeless in early childhood. She grew up in a European city.

I thought Marie curie but looks like some other fits the description. Any help will be appreciated. I searched google/wikipedia with no luck. — Preceding unsigned comment added by 183.83.244.183 (talk) 17:08, 23 April 2012 (UTC)[reply]

I doubt that you meant Hypatia but I will mention her because she deserves more publicity. What field was this scientist a pioneer in? Spinning Spark 19:25, 23 April 2012 (UTC)[reply]

You might have fun with List of female scientists before the 21st century. {The poster formerly known as 87.81.230.195} 90.197.66.239 (talk) 00:07, 24 April 2012 (UTC)[reply]

Population growth vs accelerating returns in technology

From Accelerating change:

For example, it can be claimed that inventions are generally created by a fixed population of human inventors at a constant rate, regardless of their current technological prowess, and therefore technological "progress" is actually a function of population growth, not past inventions.

Have any studies attempted to assess the accuracy of this claim, i.e. to determine whether historical statistics still support the Law of Accelerating Returns once adjusted for the (possibly superlinear, and possibly time-lagged) effect of an increased population? Neon Merlin 17:21, 23 April 2012 (UTC)[reply]

My reading of the article is that that is not a claim, but a dialectical argument against accelerating change. Personally, I very much doubt that there is evidence to back it. It just does not stack up when comparing, say, the Golden Age of Greece against the stagnation of medieval Europe. Population size will clearly come into this equation, but equally, if not more, important are good communications, a social system allowing freedom to express ideas, and a society wealthy enough to allow individuals to pursue those ideas. Spinning Spark 19:16, 23 April 2012 (UTC)[reply]

The problem with anything like this is deciding on a metric to measure the rate of invention with. I'm sure you could find plausible metrics to both prove and disprove that claim. --Tango (talk) 21:54, 23 April 2012 (UTC)[reply]

That is exactly the point being made in the quotation taken from the article. It is not a claim in itself. Spinning Spark 23:27, 23 April 2012 (UTC)[reply]

Carmine microbial production

"The carminic acid used to produce the pigment can also be extracted from various microbes engineered for the purpose." This is unreferenced- can I get some further information on microbial production of this compound? 71.223.9.1 (talk) 18:46, 23 April 2012 (UTC)[reply]

Some Biology questions

1)Till what age an average human gets taller?I mean, after what age the human height generally stops to increase?

2)Is the death is certain for every human being?.If it is provided all the necessities and is cured from all diseases then how the death would come? Max Viwe | Wanna chat with me? 19:52, 23 April 2012 (UTC)[reply]

2) Yes, death is certain. Some reasons:

2a) Parts of our body wear out. Some are never replaced, like nerve cells.

2b) Other parts can be replaced, but our bodies slow down the rate of replacement as we age. This seems to be evolution at work, using mechanisms like telomeres to ensure that we grow old and die, to make room for new individuals with new genes, so the species is better able to adapt to changing conditions. (Note that there may be a way to fight telomere shortening, as with telomerase reverse transcriptase, but there are probably other mechanisms at work, too.)

2c) We also have an accumulation of damage to our bodies, such as scars and genetic damage to DNA from UV light and other radiation.

2d) If nothing else killed us, we would eventually die in an accident or violence. There are some plants and simpler organisms with no fixed lifespan, and this is what kills them all off, eventually.

2e) As for artificial immortality: One day, if we can duplicate out brain in a computer, we might be able to live forever as a robot. With sufficient backups located far away (Pluto ?), this would make us reasonably safe from accidents, too. StuRat (talk) 20:40, 23 April 2012 (UTC)[reply]

Human height has a chart (for the US). Looking at it, it appears the average female stops at around 19, the average male at about 20. Taxes are certain; as for death, check out Immortality#Prospects for human biological immortality. Clarityfiend (talk) 21:09, 23 April 2012 (UTC)[reply]

2b the main function of telomere shortening IIRC is to prevent rogue cells from becoming cancerous and killing you early in life. Only that fraction of cancer cells that manage to switch on their telomerase genes become really dangerous. That allows you to escape cancer for quite a while at a young age (when it really matters to evolution). The breakdown of the human body is also because of antagonistic pleiotropy - some genes that let you have a good early life at the cost of long term damage. An example is the choice between a strong immune response and the body eventually slipping up and attacking itself (diabetes and arthritis).Staticd (talk) 05:13, 24 April 2012 (UTC)[reply]

Death is by no means certain - like most biological phenomena, it sort of dissolves when you try to think about it. If the two halves of your brain were split apart from each other, and put into similar heads and sewn together with halves from some other person, would you still be alive? What if you took half of each those halves and repeated? And so on, until just one neuron from your brain was in each other head? Would you be alive then? Well, what if every neuron you have in your head is more or less identical to one neuron which is in some other person's head, somewhere in the world, right now? Would you be alive then, in those heads, even if the original head were no more? Wnt (talk) 23:24, 23 April 2012 (UTC)[reply]

There is a difference between continuum of biology and continuum of self-aware personhood. Cell lines can be made to become immortal. Swapping hemispheres of the brain out would result (if it could be made to work in humans) in a completely new person. From a human perspective it is continuum of personhood that matters in the quest for immortality. Maybe we can achieve for people something similar to these lobsters. SkyMachine ⁽⁺⁺⁾ 23:59, 23 April 2012 (UTC)[reply]

1) According to Introduction to Child Development by John Dworetzky, boys reach full height between 18 and 20 years, while girls between the ages of 15 and 17. Source: Roche & Devila 1972. Using the same source, Bodyspace: Anthropometry, Ergonomics, and the Design of Work by Stephen Pheasant gives a median age for reaching adult stature as 21.2 years for boys and 17.3 for girls, although 10% of boys were still growing after 23.5 and 10% of girls after 21.1 years. Alansplodge (talk) 01:00, 24 April 2012 (UTC)[reply]

For #2: I hope so. I can't take much more than 50-60 years of this shit... --Jayron32 04:05, 24 April 2012 (UTC)[reply]

what is the year old of the donkey when it begin to bray?

which is year old of the donkey when it start to bray? it's bray from the start when it's born? thank you. 95.35.155.88 (talk) 21:16, 23 April 2012 (UTC)[reply]

Are you asking about a Chinese zodiac year? There is a year of the horse, but no donkey. If this is not what you are asking about, perhaps you can clarify your question by providing context. -- ToE 03:17, 24 April 2012 (UTC)[reply]

My guess is that the question is "at what age does a donkey start to bray?". (I don't know the answer.) --Trovatore (talk) 03:18, 24 April 2012 (UTC)[reply]

Oh, of course! Thanks. The answer might be found in some YouTube videos of newborn donkeys. I don't have the bandwidth here to receive video, but I'll check later if I reception improves. -- ToE 03:28, 24 April 2012 (UTC)[reply]

yea, I meant about the age of donkey start to bray. I have found the answer in You tube. Thank all of you95.35.240.97 (talk) 13:11, 24 April 2012 (UTC)[reply]

If you found the answer, it is polite to share it even if you were the person who originally asked it. In case someone else comes looking for the same answer. Vespine (talk) 23:21, 25 April 2012 (UTC)[reply]

Yes. The best I could find were Huey - Braying where a 4 month old donkey's bray is quite recognizable, though high pitched, and Paper Tyger Braying! where a much younger donkey (age not given, but appears to be at most a couple of weeks old) brays at the end of the video, sounding more like a dog's squeeze toy. There are a lot of baby donkey videos out there; I only scratched the surface. -- ToE 11:42, 27 April 2012 (UTC)[reply]

April 24

Curlews?

In February and March I have seen flocks of water birds wading in the flooded rice fields between Sacramento and Yuba City California. Their silhouettes and size are best described as Curlews but to me they appeared very dark or black in plumage. My Birds of North America field guide shows no illustrations or descriptions that fit the color of the many birds I have seen. I am curious about these birds. Can you help me with a well-educated guess? — Preceding unsigned comment added by 75.19.157.83 (talk) 00:59, 24 April 2012 (UTC)[reply]

Did they have the curlews' distinctive "long, slender, downcurved bills"?--Shantavira|^{feed me} 07:35, 24 April 2012 (UTC)[reply]

Yes, they did have the curlews'long, slender, downcurved bills. There were dozens of them, apparently feeding in the shallow water-filled fields. I've seen them on several different days (cloudy and sunny) but they all appeared much darker than any of the field guide illustrations. — Preceding unsigned comment added by 75.30.69.19 (talk) 01:49, 26 April 2012 (UTC)[reply]

M notation in chemical reactions described for rate data

In looking at chemical reaction rate data, I notice that common notation for describing the reactions often includes the symbol "M", which I initially thought stood for "any molecule" - a molecule that provides an opportunity for collision but is not changed by the reaction, implying that the rate is substantually independent of M. For example: CH₄ + M → CH₃ + H + M. However it seems that the rate coefficients (Arrhenius parameters) are very strongly dependent on just what molecule the M actually is. So why is the "M" notation used? Why not give the reaction in a form stating what the colliding molecule actually is, as in CH₄ + Ar → CH₃ + H + Ar? Is it some sort of historical reason? I've looked at many reaction rate papers and chemistry books - they all just use the notation without explaining why. Ratbone124.182.165.65 (talk) 02:56, 24 April 2012 (UTC)[reply]

Usually 'M' indicates a metal atom. Plasmic Physics (talk) 03:07, 24 April 2012 (UTC)[reply]

No, that can't be it. Refeences listed on the NIST database, e.g., Baulch, Cobos, etc, (J Phys. Chem. Ref Data, Vol 21 page 411 onward) use M to signify Ar, N₂, O₂, CH_n, you name it, most of them are not metals, and most are not atoms. Keit121.215.138.9 (talk) 03:36, 24 April 2012 (UTC)[reply]

M does mean "a molecule". The idea is that you're looking at a specific reaction here, which appears to be the homolytic (radical) cleavage of a hydrogen atom from methane to make a methyl radical and a hydrogen atom. If you want to do a series of studies as to the effect of various collision targets for such a reaction, you first define the general reaction, using "M" for the target, then you would have a table or chart in the article which would define rate law as a function of the identity of "M". That's, at least, how I would read this. M is a variable, which will later in the article be defined as a specific set of molecules. That would make the most sense to me, if I am reading your question correctly. --Jayron32 04:03, 24 April 2012 (UTC)[reply]

To put it another way, chemistry has a few algebra-like "variables". M = some molecule, just as H-X typically means some halide, or CH3-R means something bound to some side chain. The point is to allow the writer to say M, X, or R = this, that, or the other thing. Wnt (talk) 05:49, 24 April 2012 (UTC)[reply]

I've seen this M notation before in the context of gas phase kinetics like this. My recollection is that M stands for any atom or molecule whose purpose in the reaction is to give or receive energy by collision. M doesn't chemically react, it's just there to bump into. If, for example, a molecule of CH₄ collides with a molecule of M, CH₄ might end up with more energy than it had before the collision. You often see such "excited" species highlighted with an asterisk, e.g. CH₄*. The process would be expressed in an equation:

CH₄ + M → CH₄* + M

This isn't a chemical reaction in the traditional sense, it's redistribution of translational, rotational and vibrational energy. The important point is CH₄ becomes vibrationally excited as a result of the collision with M. Vibrational excitation ("chemical activation") is often necessary for a chemical reaction, such as the homolytic fission of a C–H bond:

CH₄* → CH₃ + H

The extra vibrational energy CH₄ obtained from collision with M has been spent on breaking the bond. This could not happen without activation, since bond breaking requires energy (is endergonic or endothermic?).

The two processes of (i) vibrational excitation by collision with M and (ii) bond dissociation often occur simultaneously, so are expressed together:

CH₄ + M → CH₃ + H + M

I've often heard M referred to as the "bath gas", meaning something like argon that you might use as an inert gas to dilute a reactive gas like methane for kinetic studies. I believe the general placeholder M rather than a specific symbol like Ar is used because M could be either an atom of Ar or another CH₄ molecule, it doesn't matter. M signifies the role of the molecule in the reaction, rather than its chemical identity. See Lindemann mechanism for an example of the use of M. --Ben (talk) 09:54, 24 April 2012 (UTC)[reply]

I don't actually know the answer, as like Ratbone I have never seen the reason or meaning for M notation explained. It seems to just get used. Clearly, whatever atom or molecule the M actually is DOES matter, and matters a great deal. Not only does the actual atom or molecule used greatly affects the rate, it affects the shape of the temperature dependence curve. But after thinking about it, I think that the following two reasons fit:-

Firstly, to clarify what Jayron is probably trying to say, M helps define a class of reactions. For example, CH₄ + M → CH₃ + H + M. defines a class of reactions, and the reactions CH₄ + Ar → CH₃ + H + Ar and CH₄ + N₂ → CH₃ + H + N₂ are members of this class. To make classifying reactions in this way worthwhile, there must be some characteristics common to the class. The rate equation definitely is not, but the reaction order (1st, 2nd, or 3rd as may be) is, and so is the fact that the M atom or molecule (whatever it happens to be) is totally unchanged.

Secondly, the M notation allows us to distinguish between reactions that don't change one of the collidants from those that change all of them. Consider a reaction AB + BC → A + B + BC, where A, B, and C are symbols of atoms. Two different things can be happening here. To explain it I'm going to invent a new notation - I will name the atoms individually like we name people. Let's say we have atoms A_ALEX, B_BRUCE, B_BRIAN, and C_CHARLES. Firstly we can have reaction A_ALEXB_BRUCE + B_BRIANC_CHARLES → A_ALEX + B_BRUCE + B_BRIANC_CHARLES. This is a case of the collision cleaving A_ALEXB_BRUCE into two, and leaving B_BRIANC_CHARLES unaltered. This is conveniently shown as AB + M → A + B + M, M = BC. Note the "M = BC" part - it is incomplete without this. Secondly, we can have reaction A_ALEXB_BRUCE + B_BRIANC_CHARLES → A_ALEX + B_BRIAN + B_BRUCEC_CHARLES. Here, Bruce has swapped partner and all products are changed cf the reactants. A more concise notation is AB' + B"C → A + B" + B'C. You might ask why worry about such a reaction - there appears to have been the same chemical result to the first case. But B' and B" could be different isotopes (remember that many elements naturally and artificially occur as a mix of stable isotopes) - then the physical characteristics and chemical properties of the products will be different in each case, though often perhaps not greatly different.

Keit121.215.68.210 (talk) 13:16, 24 April 2012 (UTC)[reply]

The exact numerical analysis and specific rate-constants may depend on the identity of M, but an even more significant major point is that M exists, with a coefficient of 1 in the reaction at all. That is, the equation illustrates that M plays an actual role in the reaction mechanism and does appear in whatever equations you would use for rate/equilibrium rather than really being an inert solvent/carrier-gas/etc. DMacks (talk) 14:12, 24 April 2012 (UTC)[reply]

Let's clear this up once and for all.

Atkins & de Paula, Physical Chemistry, 7th edition (2002), chapter 25 (the rates of chemical reactions), page 866.

"HCl* + M → HCl + M

Here HCl* denotes a thermally excited HCl molecule and M is a body (an unreactive molecule or the wall of the container) that removes the excess energy stored in HCl...

And again, on pages 900-901 (chapter 26, the rate laws of chain reactions):

Br₂ + M → Br^· + Br^· + M

where M is either Br₂ or H₂.

Br^· + Br^· + M → Br₂ + M*

In the termination step, the third body M removes the energy of recombination.

Finally, page 922:

O + O + M → O₂ + M

where M is an arbitrary third body, such as O₂ in an 'oxygen-only' atmosphere, which helps to conserve angular momentum.

Several different molecules and the walls of the container will all act as M in any given reaction. It is not possible to say that M = the bath gas Ar or M = CH₄ or M = the wall of the container. All three are possible and therefore all three will happen.

You can say one thing about the identity of M: some species are statistically much more likely to act as M. For example, imagine a gaseous mixture of bromine, Br₂, and argon, Ar, where the concentration of bromine is very low and the concentration of argon in very high. Br₂ is much more likely to collide with an argon atom than with another Br₂ molecule, simply because there is a much higher concentration of Ar than of Br₂.

On the other hand, what Jayron and Keit say about changing the bath gas is correct. If you swamp your Br₂ in N₂ rather than Ar, it changes the efficiency of energy exchange in a collision. See doi:10.1063/1.463803, for example.

If there are two or more "bath gases" present (e.g. mostly Ar with some N₂), one may be more efficient at exchanging energy in a collision. So the most likely collision partner (e.g. Ar) may not be responsible for most of the activation or deactivation. Less concentrated but more efficient quenchers (e.g. N₂) may account for more of the total quenching rate.

My point is this: even for a particular, defined mixture of gases, it is usually impossible to say "M = one particular molecule".

So there you have it. --Ben (talk) 12:22, 25 April 2012 (UTC)[reply]

Thanks, Ben, for all your care in posting, however - If it is usually impossible to say what molecule M is, even for a particular defined mixture, then what is the point of reaction rate calculations or Arrhenius data? Yes, the container walls can act as a collision partner, but in practical container sizes, won't the collisions between gas molecules far out-number collisions with the walls? So can't the walls usually be neglected? Presumably, to calculate the overall reaction rate, one needs to evaluate the rate equation for each M possible, including the wall material if necessary? So one must identify each possible M value? Ratbone120.145.51.113 (talk) 13:52, 25 April 2012 (UTC)[reply]

With low pressure gas mixtures, container walls might become important.

In practice, M often cancels out when rate equations are combined. It can also be factorised out into a pre-exponential term, which can be ignored for many purposes. --Ben (talk) 14:21, 25 April 2012 (UTC)[reply]

Diamminehydridoboron(0) [BH(NH₃)₂]

Is it possible to generate this compound, or will it fly appart like an overfilled closet? Or perhaps rearrange itself and spit out anything that doesn't quite fit, like a box full of mattress springs? Plasmic Physics (talk) 04:31, 24 April 2012 (UTC)[reply]

Apparently, diamminedihydridoboron(1+) [BH₂(NH₃)₂]⁺ does exist. Plasmic Physics (talk) 04:34, 24 April 2012 (UTC)[reply]

I'm seeing several references to diaminoboranes here, some over 30 years old: [6]. Assuming you mean HB(NH₂)₂. If, instead, you really mean ammineboron complexes, then this search shows similar complexes, such as dihydridodiammineboron(III) ions. That may give you some leads. --Jayron32 04:46, 24 April 2012 (UTC)[reply]

Note: Plasmic Physics made additions to his initial posts which make my answers seem irrelevent, but which were relevent at the time given some possible unclear ideas. --Jayron32 16:40, 24 April 2012 (UTC)[reply]

Namely, I added formulae in the title and in my second post. Plasmic Physics (talk) 21:50, 24 April 2012 (UTC)[reply]

Oxidocarbon(0) [CO] vs. trifluoridoboron(0) [BF₃]

Why on Wikipedia, are carbon monoxide and boron trifluoride both considered to have a bond order of three, even though a fourth bond is delocalizsed over the boron trifluoride molecule? Plasmic Physics (talk) 03:07, 25 April 2012 (UTC)[reply]

BF₃ has a practical bond order for each B-F bond of slightly higher than 1. The nominal bond order should be 1 1/3 if following the "octet rule" for boron. this is very approximate, however, as the boron will be highly electron deficient, so the actual electron density within the bonds themselves will be somewhat closer to true single bonds than predicted by lewis theory. Carbon monoxide has a nominal bond order of 3, the expected electron density will of course be slightly less (especially as compared to the isoelectronic N₂ molecule) because of the electronegativity difference between carbon and oxygen, meaning that some of the electron density will be localized to the oxygen rather than "in the bond". As an aside, I'm not sure why you are using metal coordination complex nomenclature for simple covalent molecules, I suppose it works, but it is awkward, and you'll not find a lot of texts using the name oxidocarbon (0) for carbon monoxide. They just use "carbon monoxide", and you probably should too. --Jayron32 03:30, 25 April 2012 (UTC)[reply]

Are you saying that the difference is simply an effect of rounding the individual bond orders between atoms within the respective molecules? Wouldn't that mean that the nitrate ion should be depicted as having all single bonds as well? With respect to your question: as you know, I am a black and white, or an eiher/or person, I like to sort everything into nice little boxes. I've decided to use the coordination complex formula notation for any molecule containing that is electron deficient, unless it is itself a ligand. As much as I'd like to, I won't introduce my systems into article pages. Plasmic Physics (talk) 04:13, 25 April 2012 (UTC)[reply]

It is black and white: If it isn't a metal-ligand coordination complex, don't use that naming system. Every serious chemist I know, even those that work in the field of metal-ligand chemistry, would consider such use of that naming system for simple molecules like carbon monoxide to be idiosyncratic to the point of being annoying. There is no gray, the naming system is used for metal-ligand complexes alone. Regarding BF₃, you'll find cases in the literature for both extremes. Since the boron in such compounds are almost universally electron deficient, boron is often depicted as having an "incomplete octet", and the lewis diagram for boranes often shows boron to form only three (rather than the expected 4) bonds.See this for one example. Some people are uncomfortable leaving boron with an incomplete octet, when there are fluorines there with lone pairs they could donate and create an octet for boron without losing one themselves; such a structure would have three resonance forms, and a nominal bond order of 1 1/3. this page, for example, takes that tack. Thus, there isn't complete consensus on how to treat BF₃ from a valence bond theory treatment. The physical data for BF₃ is somewhat inconclusive: the gas-phase bond length is somewhat shorter than a true B-F single bond would be expected to be, but it is also somewhat longer than what a 1 1/3 bond would be. If you want the nitty-gritty, I did find this journal article from 1969: [7], which would probably be fairly early work on the electronic structure of BF₃. You could certainly use it to guide your research. --Jayron32 04:50, 25 April 2012 (UTC)[reply]

See Talk:Boron trifluoride#Covalent or ionic?. BF₃ is quite ionic, so we may be stretching the truth a little too far by thinking in terms of covalent MOs. Nevertheless: are you comparing BF₃ and NO₃⁻? Think of this diagram. You want to know why the N–O bond order is higher than the B–F bond order. One reason is this: oxygen is less electronegative than fluorine, so it holds onto its electrons less tightly. Therefore oxygen donates pi electrons more easily to an electron deficient centre (to N²⁺) than fluorine does (to B). --Ben (talk) 12:39, 25 April 2012 (UTC)[reply]

I'd say it would be more accurate to say that BF₃ is highly polarized; to say it is "ionic" would imply that it actually, you know, forms ions readily, that is there should be B³⁺ and F^1- ions, either in solid form (as an ionic lattice) or in solution. I don't see any evidence that either of these things happens: it is a room temperature gas and doesn't form strongly electrolytic solutions in water. Ionic is as ionic does, and this is not an ionic compound. Heuristic tools used to determine ionic character (such as electronegativity difference or charge distribution) are secondary to actual physical and chemical properties. Instead, it is better to think of it a highly polarized molecule, rather than as distinct ions. The prevailing literature, both journals and student texts, treats it as a molecular substance, so I don't see why we shouldn't do so in this discussion here. --Jayron32 13:37, 25 April 2012 (UTC)[reply]

(edit conflict)The difference between ionic and covalent MOs is decided upon a completely arbitrary limit on the wavefunction coefficients, to create non-bonding orbitals. There really is no such thing as non-bonding orbitals, just arbitrarily weak overlap. It's a cse of how many grains of sand makes a pile. I know the true bond orders, I wanted to know why Wikipedia decides to not reflect the correct bond orders in all cases, such as the first two exaples given. Carbon monoxide has a bond order of three and it is reflected by a triple bond between carbon and oxygen, however, boron trifluoride has a bond order of four, yet only three sinngle bonds are indicated. Instead of the fourth being equally divided between the other three B-F bonds, it is completely dropped. Yet, for the nitrate ion, the bonds are depicted as aromatised and not singular bonded. I'm saying that ideally, the B-F bonds sould also be aromatised. Plasmic Physics (talk) 13:52, 25 April 2012 (UTC)[reply]

Jayron: I probably went to far, but the ionic argument goes as follows: Inorg. Chem., 1997, 36 (14), 3022–3030 "gives calculated partial charges (B: +2.43, F: −0.81) which indicate BF₃ is predominantly an ionic molecule. The fact that BF₃ does not condense to an ionic solid is explained by "size limitations on the maximum coordination number" that boron can achieve. If BF₃ adopted the AlF₃ structure (ionic solid), boron would be octahedrally coordinated by six fluorides."

See Boron trifluoride#Hydrolysis: does dissolve BF₃ in water, but it undergoes reactions. This is not a simple test of ionicity.

Plasmic Physics: let's be clear, delocalised is not the same as aromatic. And bond order refers to the strength of interaction between two atoms only. BF₃ as a whole molecule does not have a bond order. Each B−F bond has a bond order, often said to be greater than 1.

I'm saying BF₃ is drawn localised whereas NO₃⁻ is drawn delocalised because the latter is more delocalised. --Ben (talk) 14:38, 25 April 2012 (UTC)[reply]

The bond order of a molecule is calculated by subtracting the sum of antibonding electrons from the sum of bonding electrons. Plasmic Physics (talk) 23:01, 25 April 2012 (UTC)[reply]

I've never seen bond order used that way. Half the difference in the number of antibonding and bonding electrons is the usual way to calculate the bond order of a localised bond. Do you have a reference for your "molecular bond order" definition? --Ben (talk) 11:28, 26 April 2012 (UTC)[reply]

That is the way that I was taught in my paper, we use MELDs for this calculation - where it is difficult to isolate MOs of localised bonds. We calculate the bond order of the molecule, and then divide it up by combining MO theory with valence bond theory. Plasmic Physics (talk) 11:39, 26 April 2012 (UTC)[reply]

That's more like it. You normally assume the sigma framework follows the Lewis structure, so three single B–F bonds in BF₃. Then you work out any pi bonding with the MO calculations. So your B–F bond order is 1+x, where x is the fraction of a full B=F pi bond calculated to be present. What did you find for x? --Ben (talk) 12:01, 26 April 2012 (UTC)[reply]

Average x must be equivalent to ⅓ to make a total bond order of 4. Plasmic Physics (talk) 12:32, 26 April 2012 (UTC)[reply]

Simplest being to show affection

Which simplest (taxonomically lowest) living organism is capable to show affection and/or love?--176.241.247.17 (talk) 09:46, 24 April 2012 (UTC)[reply]

With all due respect, your question is very problematic. Affection and love are not concepts amenable to biological discussion. We can talk about animal behaviors, but we have very little way of knowing their internal states (which is what love and affection are in humans). You might be interested in Beetle#Parental_care, or Frog#Parental_care, but understand that we cannot say a beetle loves its children because it takes care of them. (sadly parental care is completely human-centric, we need a parental care_(biology)...) SemanticMantis (talk) 12:49, 24 April 2012 (UTC)[reply]

You may also be interested in Pair bonding and courtship displays. Both of these are interesting features of animal behavior that we sometimes interpret as being similar to human affection, even though that interpretation has no scientific basis. For a fun example of courtship in "lower" animals, enjoy this clip of a dancing spider [8] :) SemanticMantis (talk) 13:36, 24 April 2012 (UTC)[reply]

Perhaps more concisely, affection and love have conotations of conscious thought. Consider certain species of crocodile, where the parent returns to the nest, carefully digs up the hatchings, and carries them to the water. Does the parent crocodile fell affection for her little ones? Who knows? It would seem to be a pre-programmed instinct, and probably it's nothing more that the parent feeling more at ease having done it, maybe not even that. Keit121.215.68.210 (talk) 13:43, 24 April 2012 (UTC)[reply]

I don't think most dog owners would claim that their pets are not affectionate, and further complicating matters, individuals vary widely in their temperament. Some people are very selective with their affections, while others are more gregarious. In addition, there are instinctual and environmental processes that underlie our preferences. For instance, identical twins raised apart have often developed eerily similar interests. More generally, within the animal kingdom, the sharing of the many autonomic senses and experiences is as natural as sharing molecules. Thus, even though individuals do not share in everything, animals do tend to share instincts, and its completely futile to ignore the fact that we do have them too. --Modocc (talk) 18:12, 24 April 2012 (UTC)[reply]

Social grooming in animals is likely accompanied by emotional states. Bus stop (talk) 18:24, 24 April 2012 (UTC)[reply]

Ah, yes, nice link and pics too and this may explain, in part, why I've preferred using a flea comb on my pets to other flea control methods. My pets have liked the extra attention I'm giving them too. :-) --Modocc (talk) 18:37, 24 April 2012 (UTC)[reply]

You raise a very good point. Indeed, I do believe that my dog shows affection to me. However, I also know that this belief is not rooted in science. Instead, it is based upon my feelings, emotions, and anthropomorphic interpretations. I suppose there is a somewhat scientific angle from which these interactions could be studied, e.g. interspecies communication. SemanticMantis (talk) 18:56, 24 April 2012 (UTC)[reply]

I do think my position is scientific, in part, because our own conceptual models for "being affectionate and experiencing affection" are based on multiple data points with respect to our knowledge of, and interactions with, others. We each know for instance that some people are quite good at feigning affection, nevertheless we can use our knowledge of our shared biology and actions to measure the extent of individuals' affections, perhaps scaled from -10 to 10. In addition, science is about creating and maintaining valid models and the model that many animals experience affection too is simple enough to embrace as opposed to a model that we, as humans, are entirely different. --Modocc (talk) 20:53, 24 April 2012 (UTC)[reply]

Yes. I work in a high school, and it's quite normal to see some teenage boys acting very affectionately towards some girls, while all the while their primary aim is to get into their pants. But one can never be certain, can one? It may be true love. HiLo48 (talk) 21:53, 24 April 2012 (UTC)[reply]

I didn't mean to say the scientific model was that no animal can experience emotions, nor that I espouse this view. I just meant to stress that scientifically identifying and studying these emotions is extremely difficult (even in humans or chimps, let alone birds, lizards, or bugs). So I tried to provide useful links to similar -and more scientific- concepts. I should have said above "...even though that interpretation may not have a firm scientific basis." SemanticMantis (talk) 23:56, 24 April 2012 (UTC)[reply]

The old idea that animals could not experience emotions or true affection was not really rooted in science either. It was certainly influenced by religious ideas about the nature of humans vs. other animals. It's not an easy thing to study scientifically, but Occam's razor certainly points toward some animals having some of the same emotions we do.--Srleffler (talk) 17:56, 26 April 2012 (UTC)[reply]

"Taxanomically lowest" (in the original question) is also problematic. By what scale? --ColinFine (talk) 19:32, 24 April 2012 (UTC)[reply]

Taking bacteria as being the taxonomically highest because they are at the top of the clade tree (they are also arguably top of the food chain) and everything that has descended from bacteria as being taxonomically lower in heirarchies, then the answer to the original question is human beings. Spinning Spark 11:52, 25 April 2012 (UTC)[reply]

Certainly birds show "affection or love." I have observed a Guinea pig and a canary who were fond of one another (the bird laid eggs for the first time only after the male Guinea pig was housed in a cage near her cage, and they vocalized constantly to one another). When the Guinea pig was removed (returned to school after being housed during holiday), the canary was obviously depressed for a time (off her feed, and less grooming and vocalization). Edison (talk) 04:57, 25 April 2012 (UTC)[reply]

When I step on my dog's paw he yelps like I would if my hand were similarly stepped on. When I forget to let him in and it's raining he whines like I would. When I scretch his ear he moans in a way that I would if I were getting a full body massage. When I cried after a serious injury he would come to me as if to say "what can I do to help?". That shows some type of concern, which one might consider care. I colud go on..165.212.189.187 (talk) 13:20, 25 April 2012 (UTC)[reply]

In other words, your dog displays behaviors that, if he were human, you would interpret as human affection. That just means you are projecting your own anthropomorphized image of his behavior, and doesn't mean he experiences the internal emotion we humans call affection. Until dogs can tell us what they feel, we're just left with behaviors. There is not necessarily any evidence that a dogs behavior has any connection to an internal emotional state in a way that is analogous to humans. --Jayron32 13:15, 26 April 2012 (UTC)[reply]

So just explain the whining if its barely audible and the moaning if it is not because it feels sooo good?165.212.189.187 (talk) 16:12, 26 April 2012 (UTC)[reply]

Identifying affection from behaviors in nonhuman animals does not just simply imply anthropomorphism, which is a form of overgeneralization, though. Such an error can happen should there be no emotion occurring with a behavior, and people mistakenly believe there is anyway on account of the behavior, and we are rightly skeptical about supposing ants having affections, even if its just a tiny +-.01 bit. Of course, many actors that seem affectionate are not, therefore if we are to believe only what we are verbally told to be true (and ignoring other forms of communication), then one can argue that there isn't any reliable evidence that mans behavior has any connection to are own personal states either. Its a very poor position.. to be unplugged from if necessary when people go further denying that reality exists too because they cannot trust their own senses. Nevertheless, we have much more concrete evidence, from known common cell types to common brain structures, along with various complex behaviors that support the claim that dogs experience affection. --Modocc (talk) 14:40, 26 April 2012 (UTC)[reply]

I've seen stories on TV, including but not exclusive to Animal Planet, about various cross-species friendships between animals. One especially touching story had to do with an animal compound or zoo in which an elephant had become fast friends with a dog. The dog was taken to the hospital for surgery, and the elephant waited outside the hospital until the dog was well enough to be let loose again. The joy in both animals was evident.[9] And later, when the dog was killed, apparently by a pack of coyotes, the elephant carried the dead dog back to the main area, and moped for days. ←Baseball Bugs ^{What's up, Doc?} carrots→ 13:48, 25 April 2012 (UTC)[reply]

Hermaphroditism

Does this NSFW image depict a true hermaphrodite, or just a person with both genetalia? Crisco 1492 (talk) 10:20, 24 April 2012 (UTC)[reply]

Well, the museum page shows the person was a hermaphrodite. --SupernovaExplosion ^Talk 11:55, 24 April 2012 (UTC)[reply]

According to this paper (p.3), "As early as 1860 the French photographer ... Nadar, took a series of nine photographs – which I take as the first examples of medical pictures of intersex patients ... that depicted a young intersex patient. They show the genitals of a hermaphrodite...". --SupernovaExplosion ^Talk 12:00, 24 April 2012 (UTC)[reply]

There is a journal article titled Early Photo-Illustration of a Hermaphrodite by the French Photographer and Artist Nadar in 1860. Hope this clears all the doubt. --SupernovaExplosion ^Talk 12:01, 24 April 2012 (UTC)[reply]

In that case these photographs could have their own article... Imagine the DYK... But if I'm not mistaken, intersex and hermaphrodite are different. Crisco 1492 (talk) 12:51, 24 April 2012 (UTC)[reply]

In humans, hermaphroditism is a very specific (and probably non-existent) subset of of the spectrum of intersex conditions. --Carnildo (talk) 02:21, 25 April 2012 (UTC)[reply]

The picture should be moved to a file name that spells "genitalia" correctly. - Nunh-huh 02:52, 25 April 2012 (UTC)[reply]

True hermaphroditism in humans is not possible. The measure is functioning reproductive systems of both sexes. In humans, the competing hormonal levels would wreck the individual's ability to thrive. What you actually get is someone whose external sexual characteristics resemble both genders, but functionally only one of those sexes works. And I use "functionally" in the loosest terms. — The Hand That Feeds You:^Bite 15:05, 25 April 2012 (UTC)[reply]

Our True hermaphroditism article suggests true hermaphroditism in humans normally refers to an individual who has both ovarian and testicular tissue. It also notes that no case is known where both gonodal tissues were functioning but there have been cases where one of the tissues has been, and the individual was fertile. Although as our hermaphrodite article notes with a link to [10], the term is no longer preferred among many in the intersex community and elsewhere and there are more descriptives alternatives like those mentioned in disorders of sex development. In any case, I expect it is fairly unlikely that we have sufficient info on the person in the photo to know if they will fit in to the true hermaphrodite description. (For example Pseudohermaphroditism wasn't cointed until 1876.) Nil Einne (talk) 16:54, 25 April 2012 (UTC)[reply]

To become supercentenarian

What measures should be taken by someone in their mid-20s to become a supercentenarian? --SupernovaExplosion ^Talk 13:47, 24 April 2012 (UTC)[reply]

Choose your grandparents well. --TammyMoet (talk) 13:55, 24 April 2012 (UTC)[reply]

What I've heard is that a good food, good air, a peaceful state of mind, a strong relationship, and a daily mission to do, are all condusive to a long life. Conversely, a poor diet, polluted air, stress, lonesomeness, and boredom/lazyness are condusive to an early grave. Plasmic Physics (talk) 14:01, 24 April 2012 (UTC)[reply]

Is that medical advice?165.212.189.187 (talk) 15:37, 24 April 2012 (UTC)[reply]

No. See Wikipedia:Reference_desk/Guidelines/Medical_advice#What_does_this_guideline_apply_to.3F. --SupernovaExplosion ^Talk 15:44, 24 April 2012 (UTC)[reply]

Be lucky. There are certainly lifestyle choices that will affect how long you are likely to live, but if you're talking about living to 110 or over, then luck is really the biggest factor. --Tango (talk) 18:48, 24 April 2012 (UTC)[reply]

A near starvation diet seems to prolong life, but I'm not sure if it's worth it. StuRat (talk) 18:51, 24 April 2012 (UTC)[reply]

It is literally a case of "use it or lose it" - people will lose their mind and their strength, the less they use it. The older you get the easier it becomes (to lose), and the longer it takes to return to normal, it may never return to normal. Plasmic Physics (talk) 21:58, 24 April 2012 (UTC)[reply]

But you can also overuse your body, resulting in damage. There's an ideal amount of exercise, and either more or less is harmful. Muscle-bound body-builders aren't particularly healthy, for example. This might apply to the overuse of the mind, too, if you're thinking so hard each day you give yourself headaches, for example. StuRat (talk) 22:04, 24 April 2012 (UTC)[reply]

I recall an article in Scientific American a few years ago. The authors interviewed various 100+ year old perons in the USA to find out what those persons thought enable their long life. It turned out there were NO common exercise, food, or other common factor, apart from one: Most of them had close relationships with great- and great-great grandchildren, and/or were actively involved in some community project. Well educated people and people working in teaching or research roles in academia tend to live longer. So, what can someone in their mid-20's do? Plan on having many children, get an advanced degree from a good university. Wickwack120.145.51.113 (talk) 00:09, 25 April 2012 (UTC)[reply]

I bet none of those people were morbidly obese. StuRat (talk) 01:23, 25 April 2012 (UTC)[reply]

Indeed "not doing what they didn't do because that's probably what killed the others" might be a better mentality here than copying. --145.94.77.43 (talk) 13:14, 26 April 2012 (UTC)[reply]

Many Japanese people live to old age, while Japanse people who emigrated to the US don't tend to live very long. In a BBC documentary they showed people in Okinawa; what looked to be 70 year old pensioners cleaining their yard, were in reality 90 to 100 year old people. While it is difficult to point to what specifically you must eat, it is easier to point to things that are unhealthy, like e.g. getting your lunch here.

I think the best thing to do is to use supplements as adviced here, except that the reccomendation for vitamin D is too low. The optimal dose for vitamin D is 10,000 IU/day, as that is what you would naturally get day after day, if you were to live like our Stone Age ancestors.

Also, exercise is important, you should make sure your power to weight ratio is at least 4 Watt/kg. This means that if you weigh 60 kg, you should be able to do 240 Watt on a hometrainer, for at least 30 minutes. Note that top athletes typically have a power to weight ratio of 6 Watt/kg or more.

If you are already past the age of 30 and you have not maintained your fitness (you are sort of a couch-potato), then achieving this fitness goal may be too difficult. In that case, you should first build up your fitness level as best as you can and then use drugs like EPO and anabolic steroids for a short time under medical supervision, to boost your fitness level and then stop using these drugs. While your fitness level will decline a bit after you stop, it will remain permanently above what you could have achieved without using these drugs. Count Iblis (talk) 00:54, 25 April 2012 (UTC)[reply]

Yowzer! Terrible advice. The Linus Pauling Institute as a source? Really?? Have you seen our article on Linus Pauling and Megavitamin therapy? Vespine (talk) 23:10, 25 April 2012 (UTC)[reply]

The institute is named the "Linus Pauling institute", it employs researcher who publish their work in the regular scientific journals, it's certainly not pseudoscientific garbage what they are doing there. Apart from the rather high recommendation for the vitamin E supplementation, there is nothing "mega" about the doses they recommend. Count Iblis (talk) 19:35, 26 April 2012 (UTC)[reply]

Most of the world's supercentenarians will have never been near a hometrainer, let alone studied their power to weight ratio. As for using drugs, not a chance. HiLo48 (talk) 20:06, 25 April 2012 (UTC)[reply]

That's because they were already over 50 when the first hometrainers were sold in shops. Low testosterone levels are implicated in a whole host of diseases. Keeping your testosterone levels at the level normal for young people as you get older and older, will allow you to exercise and stay fit as you age. Count Iblis (talk) 19:46, 26 April 2012 (UTC)[reply]

That sounds more like marketing guff than evidence based. No-one who has followed your advice is yet a supercentenarian, and it's only your faith that says they one day will be. What's wrong with the old approaches that worked? HiLo48 (talk) 20:35, 26 April 2012 (UTC)[reply]

SupernovaExplosion, you may find interesting information at http://www.longevityexperts.com/ and http://www.supercentenarian.com/ and http://www.supercentenarian-research-foundation.org/.

—Wavelength (talk) 01:05, 25 April 2012 (UTC)[reply]

Thanks everyone for the replies. --SupernovaExplosion ^Talk 03:35, 25 April 2012 (UTC)[reply]

There's more to life than just living. Broba (talk) 22:00, 25 April 2012 (UTC)[reply]

Photoelectric effect- why Kth shell??

"in Photoelectric effect the electron is ejected from Kth Shell"...the narrow syllebused book dosent say why?..so i m asking why Kth shell why not outermost shell...please explain theoretically and not mathematically...i did read about it sumwhat but it just got over my head..Thankks--Myownid420 (talk) 14:25, 24 April 2012 (UTC)[reply]

I'm not sure where that quote came from. It's most likely that an electron will be knocked out of the outer shell, because those are bound more loosely. The "shells" aren't solid like an eggshell, though, they're probability densities. High-energy particles can pass through the outer shells and knock out inner-shell electrons as well. 130.76.64.116 (talk) 20:08, 24 April 2012 (UTC)[reply]

The use of kth shell instead of K shell would lead me to believe that your book does not mean the innermost (K) shell, but rather is using the symbol k as some kind of index. You will need to give a fuller quote from the book (or maybe it can be found online from the isbn). If the book is discussing hydrogen or helium, the K shell will, of course, also be the outermost (and only) shell. Spinning Spark 22:23, 24 April 2012 (UTC)[reply]

GPS or Glonass which came first

Hi,

Of GPS and Glonass which came first? The corresponding articles do not seem to give a clear picture, of which of the systems had started construction first. — Preceding unsigned comment added by Gulielmus estavius (talk • contribs) 18:30, 24 April 2012 (UTC)[reply]

GPS was initially developed in 1973 and became fully operational in 1994, as stated in the GPS article. Glonass was initially developed in 1976 and became fully operational in 1995, according to that article. I'm not sure what confusion you are having; I got that information from the lede of each article. --Jayron32 19:02, 24 April 2012 (UTC)[reply]

Per the articles, GPS was developed in 1973, the first test launch was in 1978, the first modern GPS satellite was launched in 1989, and full operational capability (of 24 satellites) was attained in 1994. GLONASS development, meanwhile, began in 1976, with an initial launch in 1982, and a full constellation of 24 satellites reached in 1995. So, GPS was developed on paper first, launched first, and and was fully operational first, by approximately the same margin throughout the process. Note also that GPS attained first major military use during the first Gulf War, in 1990-1991, prior to officially reaching its full capability. — Lomn 19:03, 24 April 2012 (UTC)[reply]

Electric motor and heat

I have a simple electric AC fan that seems to take some time to speed up to maximum speed. Normally I would think this was momentum, but after it's been running, if you turn it off, let it stop, and then turn it back up, it quickly returns to top speed. Much quicker than int he first place. I suppose I'm measuring speed based on loudness, but I think that's a reasonable assumption.

My question is why? I suppose the motor operates better at a certain temperature, but I can't find an explanation why in our electric motor article. Any ideas? Shadowjams (talk) 20:43, 24 April 2012 (UTC)[reply]

The viscosity of the lubricating oil will change with temperature. The thicker oil, when cold, will make it move slowly. This is most noticeable when you have a tiny motor barely up to the task. Unfortunately, our cold start and warm start articles seem to be exclusively about computers, and hot start is exclusively about aviation. StuRat (talk) 21:35, 24 April 2012 (UTC)[reply]

Has the fan been stored for a while? Is it an old fan? It is common for such fans to display this effect, as dust and absorbed impurities from the air increase the viscosity of the oil, also the oil tends to dry out. Also, as the bearings warm up, they expand slightly, making them looser. To fix, put one or 2 drops only of sewing machine oil or light household oil into each bearing. BE SURE to not use too much oil. Keit121.215.39.8 (talk) 23:57, 24 April 2012 (UTC)[reply]

trial

Is the Anders Behring Breivik trial on Court TV or any other TV channels or Internet streaming sites. I saw some video clips of the trial on the BBC website and you could see reporters were recording the trial with video cameras. So shouldn't it be live streamed somewhere? — Preceding unsigned comment added by 64.38.226.88 (talk) 22:16, 24 April 2012 (UTC)[reply]

Why should it be? It might be, but it might equally be restricted, either for reasons of public policy or for commercial reasons. (This question might have been better asked at the Entertainment reference desk). --ColinFine (talk) 23:20, 24 April 2012 (UTC)[reply]

In the UK the TV news channels and programmes are not giving this man much coverage and I saw TV coverage that showed that newspapers in Norway acted together to keep him and reports of his trial from the front pages and inhibit any publicity he may be seeking. I doubt you will find it live streamed anywhere. Richard Avery (talk) 07:09, 25 April 2012 (UTC)[reply]

The BBC reported that "Parts of the trial will be shown on television, but the court will not allow Breivik's testimony or that of his witnesses to be broadcast" [11] AlmostReadytoFly (talk) 12:59, 25 April 2012 (UTC)[reply]

Hard to figure why this question is in this particular desk. But the obvious reason not to live-cast the testimony of that character and whatever witnesses he might dredge up, is to try and deny or minimize his potential opportunity to turn the trial into a personal forum. ←Baseball Bugs ^{What's up, Doc?} carrots→ 13:40, 25 April 2012 (UTC)[reply]

The reason given by the court is twofold (I've only found a source in Swedish): one reason is that a live transmission would influence Breivik's testimony, the other is consideration for the victims and their families.Sjö (talk) 17:44, 25 April 2012 (UTC)[reply]

Some official information from the Norwegian court authortities here (in English). Jørgen (talk) 20:50, 25 April 2012 (UTC)[reply]

Global warming and Mexico

How is global warming likely to affect mexico? Will more people move to high altitudes like Mexico City? Will it be a worse catastrophe for Mexico than it will be for the United States? Will Mexico be able to sue industrialized nations in the World Court?198.189.194.129 (talk) 23:30, 24 April 2012 (UTC)[reply]

More polar nations will tend to benefit, while more equatorial and coastal nations will tend to suffer, but weather patterns may change in unpredictable ways, so it's not a certainty for any particular nation. I would guess there would be more hurricanes of greater severity hitting Mexico, and that low-lying coastal areas will suffer frequent flooding, as sea levels rise. The Yucatán Peninsula appears to be the most vulnerable to hurricanes.

The chances of such a lawsuit working are close to zero. StuRat (talk) 23:43, 24 April 2012 (UTC)[reply]

Although it could be entertaining to watch Mexico try to sue India and China. ←Baseball Bugs ^{What's up, Doc?} carrots→ 13:41, 25 April 2012 (UTC)[reply]

April 25

pH Determination

What caused compounds to have lower pH values than other compounds? — Preceding unsigned comment added by Bibibubsy06 (talk • contribs) 08:24, 25 April 2012 (UTC)[reply]

Well usually they are more acidic. For the common type of acids they will produce more H⁺ ions. This may be because the H+ has less force and energy attaching it to the rest of the acid. It may be because the rest of the acid molecule has lots of atoms that attract electrons, eg trifluoroacetic acid has a lower pH than acetic acid. Graeme Bartlett (talk) 11:13, 25 April 2012 (UTC)[reply]

pH is an property of a solution--generally speaking the greater concentration of "whatever dissolved chemical", the lower the pH if an acid or the higher if a base. The "acidity or basicity" of a compound is termed pKa. So Graeme's TFA is more acidic than acetic acid--the chemical has a lower pKa. But a dilute solution TFA might still be "only very slightly lowered" (for example, pH 6.8) because it is dilute even though the acid itself is a intrinsically stronger. DMacks (talk) 21:13, 25 April 2012 (UTC)[reply]

Chemical kinetics - why no 2nd order reaction data?

Considering a quantity of contained pure hydrogen gas, it will come to an equilibrium monotomic (H) and diatomic (H₂) mixture. Logically, it seems to me that the following 2nd order reactions will occur:-

H + H → H₂.....................(1)

H + H₂ → H + H + H.........(2) normally written as H₂ + M → H + H + M, [M = H]

H₂ + H₂ → H + H + H₂......(3) normally written as H₂ + M → H + H + M, [M = H₂]

and the following 3rd order reactions will occur:-

H + H + H → H₂ + H.........(4) normally written as H + H + M → H₂ + M, [M = H]

H + H + H₂ → H₂ + H₂......(5) normally written as H + H + M → H₂ + M, [M = H₂]

Since it seems that nobody has discovered H₃, thre is no need for any more reactions such as H + H₂ → H₃. Upon a search, I found reaction rate data (eg Arrhenius quation constants) for Reactions (2) through (5), for example in Journal of Physical Chemistry Reference Data Vol 12 1983 Page 531-590. I have found data in other publications as well. However, I cannot find reaction rate data for Reaction (1). Is there some reason why this reaction can be ignored? Given that a quantity of gas is represented by particles of size <<< the mean distance between them, the probability of two molecules coliding in a given length of time must be considerably greater than three molecules colliding. What have I not realised? Some databases (eg NIST Chemical Kinetics database) list Reaction (1) in indexing, but when you follow the trail, you'll find that they actually meant H + H + M → H₂ + M, and didn't bother to write the M, which suggests perhaps that either they were slack, or that users ought to know there should be an M, or both. Ratbone120.145.51.113 (talk) 08:44, 25 April 2012 (UTC)[reply]

What you are asking is basically why can't two hydrogen atoms collide and make H₂. This has been asked before, see http://en.wikipedia.org/wiki/Wikipedia:Reference_desk/Archives/Science/2011_February_24#Question_on_collision_between_hydrogen_atoms_.28momentum_.2F_energy_question.29. Essentially, the answers there seemed to be that the sum of kinetic energy and bond energy must be conserved, and this means that if H₂ is formed the conditions exist to immediately split it again. To form H2, a third collision partner is required to carry off some kinetic energy so that the bond energy lost has somewhere to go. The transfered bond energy can then gradually transfer to the bulk of the gas by subsequent (non-raective) collisions. I have to say I'm not confortable with this explanation - why can't the newly formed H₂ molecule race off with increased velocity, to be dissipated in subsequent collisions? See also http://en.wikipedia.org/wiki/Wikipedia:Reference_desk/Archives/Science/2012_January_17#Order_of_chemical_reaction. Keit120.145.175.169 (talk) 03:39, 26 April 2012 (UTC)[reply]

To answer your last question, it has to do with conservation of momentum. The momentum of the hydrogen molecule formed would have to be equal to the sum of the momenta of the hydrogen atoms that formed it; there's no way for it to suddenly pick up speed. TenOfAllTrades(talk) 04:30, 26 April 2012 (UTC)[reply]

Inappropriate paint

Apparently an inappropriate paint was used on the cabinets above my stove, since the paint is peeling as a result of rising steam from cooking. When I repaint, what type of paint would be best to resist this effect ? StuRat (talk) 16:15, 25 April 2012 (UTC)[reply]

Hey, I can't believe you couldn't have done this. Richard Avery (talk) 16:59, 25 April 2012 (UTC)[reply]

I want paints which are steam resistant, not paints where the manufacturer claims they are. StuRat (talk) 18:06, 25 April 2012 (UTC)[reply]

I don't know about steam per se, but in terms of bathrooms and other areas where one expects moisture, a more important factor in preventing peeling is often the use of a good primer rather than the choice of paint itself. The primer creates a moisture barrier and improves adhesion to the surface, which helps resists peeling and cracking that could occur after frequent exposure to moisture. I assume that similar principles apply in the presence of steam. Did you use a good primer the first time? Dragons flight (talk) 18:24, 25 April 2012 (UTC)[reply]

It was already painted when I moved in. StuRat (talk) 18:38, 25 April 2012 (UTC)[reply]

Ita erat quando hic adveni. Heard that excuse many times before ;-) --Aspro (talk) 19:10, 25 April 2012 (UTC)[reply]

Heus, modo itera omnia quae mihi nunc nuper narravisti, sed nunc Anglice? Spinning Spark 21:08, 25 April 2012 (UTC)[reply]

Well parried but not quite touché – “I only rented this cheap loco poco (little hovel) (or Poco Loco – a little crazy) because my daddy din'nt have job at the time and so threw me and my entourage out the house. Just look at the dump I've landed in.” Hardly the situation that Ovid would have found himself in -don'nt you think?--Aspro (talk) 17:56, 26 April 2012 (UTC) [reply]

If we are talking about a rental (or some low cost new construction), it isn't uncommon to see landlords doing cheap / quick painting that looks good for a bit but won't last. For example, a coat of the cheapest paint available with no priming and without cleaning up old layers. Often landlords aren't even required to maintain the look of a place. As long as there isn't a safety issue, the renter may be out of luck when the paint starts to peel. Dragons flight (talk) 19:53, 25 April 2012 (UTC)[reply]

Having been a tenant, and later a landlord, I can say that although you do occaisonally get bad tenants, and occaisonally there are skinflint landlords, the most common problem is ratbag managing agents in league with roque maintenance contractors. So if a tenant reports something needs some work, the managing agent calls his pet maintenance contractor, who does a shonky job (or even no job) for a cheap price, and the managing agent tells the owner/landlord that work needed to be done, and here's the (high price) cost. After a while, the tenants get pissed off due to the poor quality maintenance and having to make lots of complaints, and the owner thinks all the expense is due to a bad tennant. Good managing agents are worth their weight in gold. At the same time, as an owner you learn a lot if you have a beer with your tenants now and then. Wickwack58.167.243.91 (talk) 04:38, 26 April 2012 (UTC)[reply]

europa europa

Forgive me for my ignorance, but as far as I know, you cannot differentiate between an erect circumcised and uncircumcised penis. So, why did the protaganist(Jupp) in Europa Europa avoided sex with hot Leni.--122.161.40.115 (talk) 22:24, 25 April 2012 (UTC)[reply]

I expect you could if you looked closely enough. Also, don't forget the floppy-time, after. :-) StuRat (talk) 22:29, 25 April 2012 (UTC)[reply]

Humans can be highly emotional and irrational creatures. Bruce Hood performed a social experiment where he offered people money if they put on a sweater for 15 minutes that used to belong to a serial killer (not even really, but he said it was). More then half of the people asked wouldn't do it. Even if you can't tell the difference, there is a perceived "essence" to things which can emotionally repulse us, or attract us for that matter. In another experiment, children are asked if they mind if one of their toys is replaced with an identical copy. For the most part they don't mind, but if they have a favourite toy, they refuse to exchange it, even if the replacement is indistinguishable from the original. Vespine (talk) 22:58, 25 April 2012 (UTC)[reply]

(original poster here) how is this related to the original question? Or are you trying to imply that he didn't screw lina for psychological reasons rather than getting himself caught pants (and foreskin) down.--122.161.40.115 (talk) 16:48, 26 April 2012 (UTC)[reply]

I always wondered what Bruce Hood did after he retired from the NHL. There's an old saying in regard to objects from questionable sources: "You don't know where it's been!" Or in some cases, you do, and that's sufficiently repellant. However, it also might depend on how much money was offered. ←Baseball Bugs ^{What's up, Doc?} carrots→ 23:32, 25 April 2012 (UTC)[reply]

Of course, I think he was only offering $10 or $20. Vespine (talk) 01:21, 26 April 2012 (UTC)[reply]

Wearing John Gacey's sweater should be harmless, provided it was certifiably, thoroughly laundered first. ←Baseball Bugs ^{What's up, Doc?} carrots→ 02:28, 26 April 2012 (UTC)[reply]

Err, you can tell the difference. Google it up if you are really curious. --Mr.98 (talk) 01:24, 26 April 2012 (UTC)[reply]

Google says that it is not possible to know if an erect penis is a circumcised one or an uncircumcised one under normal circumstances. Obviously a medical practitioner in a lab will find out as one of the difference is that the skin gets cornified in the case of circumcised ones. However, a normal girl in a sexual intercourse cannot find that out.--122.161.40.115 (talk) 16:48, 26 April 2012 (UTC)[reply]

In addition to what the other two first level indenting posters have said, bear in mind as our Foreskin, the degree of retraction during an erection (without manual retraction) varies so in some individuals it may be as easy as with an unerect penis. And of course even if the foreskin does retract by itself, it doesn't mean it can't be moved to partially or completely cover the Glans during an erection, in fact this is a common masturbation technique and the similar movement during sexual intercourse is cited as one reason by circumcision opponents for the alleged harm. Of course some men with phimosis can't retract the foreskin fully at any time. Nil Einne (talk) 15:40, 26 April 2012 (UTC)[reply]

What I am saying is that Jupp could have passed off as a normal case. Am I wrong? --122.161.40.115 (talk) 16:48, 26 April 2012 (UTC)[reply]

Bicycle wheel spoke breakage load question

Hi. I have a pretty standard bicycle, with (AFAICS) standard steel spokes on the wheels. One broke the other day. How much force does this take? I would estimate, using the figure for carbon steel on Ultimate tensile strength of 500 MPa, and an area of $10^{-6}{\rm {m}}^{2}$ a breaking load of 500 Newtons, which doesn't seem very much. I would have estimated 5000 Newtons. Have I erred in my calculation, or is my expectation wrong? Robinh (talk) 23:26, 25 April 2012 (UTC)[reply]

110 pounds breaking force? Sounds about right. --Carnildo (talk) 01:01, 26 April 2012 (UTC)[reply]

Is tensile strength the right measure? You weren't stretching the spoke. Depending on how it broke, it was either due to compressing the spoke (so you want the compressive strength, which doesn't have any examples other than concrete, unfortunately) or it broke because it was pushed sideways, in which case I'm not sure what measure of strength is relevant. --Tango (talk) 01:46, 26 April 2012 (UTC)[reply]

Tensile strength is the right meassure. In any case, in metals, compressive strength is equal to tensile strength, in theory. But you almost never get to meassure compresive strength in metals because in compression they will bend. A bycicle spoke is such a long thin specimen that compressive strength is totally irrelevant. In my experience, broken spokes are a common occurance and occur due to travelling over severe bumps or misjudging a curb jump. This puts sudden compression in adjacent spokes, which merely bend, and sudden high tension in opposite spokes, which break. Wickwack58.170.143.160 (talk) 02:44, 26 April 2012 (UTC)[reply]

(OP) thanks guys. I'm relieved to discover that broken spokes are common. The spoke "popped" when I was cycling along, not going over a bump or anything. It just went sproing and then I noticed that the wheel had buckled (badly enough to exert the brakes every revolution). Is this normal too? Robinh (talk) 07:34, 26 April 2012 (UTC)[reply]

If a spoke (or more) breaks, then yes, it is normal for the wheel to be defromed.

As a temporary fix, you can adjust the length of the other spokes to get the shape of the wheel closer to normal. This takes a tool and a lot of practice. You must aim for the wheel to be planar so that the breaks can work, but the wheel will likely still have a bump, giving an uneven ride. (You must also remove the broken spoke from the wheel.) This is a temporary fix not only because of the uneven ride, but also because the rest of the spokes and the rim will now have to take more stress, and thus other spokes can break or the rim can get damaged.

As a permanent fix, you must replace the broken spoke with a new one, then adjust the spokes again. You can have this done in a bicycle service if you don't have enough practice. Obviously if the rim is very damaged, then you might have to buy a completely new wheel instead.

– b_jonas 09:32, 26 April 2012 (UTC)[reply]

Bicycle spokes nearly universally break not because of overloading, but because of metal fatigue due to the repeated loading and unloading of the spoke, with corresponding stress in particular at the knee of the spoke. Spokes in a well-build wheel rarely break, but if spoke tension is too low, the loading/unloading effect during rotation is more pronounced, and the spoke will break earlier. If the spoke tension is high enough, all spokes will remain under tension permanently, so the metal will not deform significantly. Except for high-end models, modern bicycle wheels are machine-build, and should be re-tensioned after a few hundred kilometers. Unfortunately, doing this is a job for an expert. But it is well worth the money. --Stephan Schulz (talk) 18:03, 26 April 2012 (UTC)[reply]

April 26

what is dark matter

what is matter which has only gravitational activity ,not electromagnetic not thermodynamic and so on,does the light pass through such matter ?I have problem with thermodynamic properties of dark matter.Akbar mohammadzade--78.38.28.3 (talk) 04:10, 26 April 2012 (UTC)[reply]

No one really knows what dark matter is, although there are numerous hypotheses; see the Dark matter article. Red Act (talk) 04:18, 26 April 2012 (UTC)[reply]

It is an invention, to explain the break down of gravitational theory on the large scale of galaxies and the universe. Gravity does not seem to function as the current threories predicts it to, so instead of modifying existing theory, cosmologists have invented dark matter. That is dark matter's sole purpose. Plasmic Physics (talk) 05:49, 26 April 2012 (UTC)[reply]

What Plasmic said. It doesn't "exist" except on paper, and even there some have challenged the rationale behind it. Evanh2008 (talk) (contribs) 05:51, 26 April 2012 (UTC)[reply]

Well now saying it like that makes it sound like physicists are lazy. Truth is there have been dozens if not hundreds of proposed alternative explanations for the observed gravitational anomaly, but the only one that is completely consistent with observations is some "missing mass": dark matter. And until we come up with better observations or a better theory we'll just have to go on not knowing what exactly that dark matter is. I don't like it, but it is what it is. And don't even get me started on dark energy.-RunningOnBrains^(talk) 06:07, 26 April 2012 (UTC)[reply]

Ok then, what do you make of Einstein's self professed fudge: the gravitational constant, which now appears to be not so constant after all? Plasmic Physics (talk) 07:17, 26 April 2012 (UTC)[reply]

It's actually just a sign of how good his theory was. The GR equations popped out, they said "the universe is not static," Einstein said, "dang, that doesn't sound like what the astronomers are saying, does it?" and so he added the cosmological constant in there to make it match the observations. Later the astronomers figured out that they had been wrong and it was expanding, and if you remove the constant, GR works great as it ought to. So it's actually something in favor of GR, not against it. Einstein called it a "blunder" because he ought to have trusted his equations more and discovered something fundamental; instead he trusted the astronomers too much and fudged the equations. --Mr.98 (talk) 12:40, 26 April 2012 (UTC)[reply]

It is just as reasonable for a child to believe in the tooth fairy, because they can't explain why money magically appears when they leave a tooth under a pillow. Plasmic Physics (talk) 07:21, 26 April 2012 (UTC)[reply]

And your argument is just as bad as saying to that child, "You're wrong because your theory is silly." We've been waiting 80 years for someone to propose a theory of gravitation that doesn't require dark matter to explain galactic motion. Alternatives to the ~~tooth fairy~~ dark matter theory have been proposed but they all suck. You could certainly argue that the theory of dark matter also sucks since it never told us how to identify the invisible little buggers, but at least it didn't require a fundamental rewriting of well-tested physical laws. Someguy1221 (talk) 07:36, 26 April 2012 (UTC)[reply]

I wasn't saying that the theory is wrong, just that everyone of them tastes funny because they are all half-baked, they took their dark matter brownies out of the oven and served it too early. Plasmic Physics (talk) 07:44, 26 April 2012 (UTC)[reply]

Note that we now have fairly strong evidence for dark matter. MOND theories can, with some fudging, explain some features of galaxy rotation. But they are hard to apply to things like the Bullet Cluster, MACS J0025.4-1222, and Abell 520, where galaxy collisions have basically separated the interstellar gas (and hence most of the baryonic mass) from the stars, but the majority of the total mass of the galaxy has stayed with the stars. --Stephan Schulz (talk) 19:40, 26 April 2012 (UTC)[reply]

I would also note that the 'half-baked' part suggests a lack of understanding of how science and the scientific method works. You don't leave a theory in the oven (whatever that means) because it isn't cooked yet. Speaking in a very, very simplified manner, someone comes up with one or more hypothesis to explain some finding. (You don't generally wait until you have an extreme amount of evidence before publicly proposing something since it means both that someone may get there ahead of you, and that others can't consider your findings and attempt test them in various ways.) As evidence accumulates, other scientists come to accept your hypothesis/es as a valid scientific theory. If at some stage, evidence emerges which appears to contradict your theory you either refine it or (you or someone else) come/s up with a new one that better fits all the evidence. Scientific understanding is constantly changing, so it's difficult to say something is 'done' or fully baked, although obviously different theories can be at different stages of acceptance with different amounts of evidence in support of them. Nil Einne (talk) 20:55, 26 April 2012 (UTC)[reply]

Returning to the original question, dark matter (hypothetically) does not interact with or "feel" the electromagnetic force, which is "carried" by photons - so, yes, light will pass right through it. It does not interact with the strong or weak forces either. The only one of the four fundamental forces that affects it is gravity. I don't think this means it has no thermodynamic properties - thermodynamics arises from statistical mechanics, which would still apply to dark matter. However, with only relatively weak gravitational interactions to distribute energy, it could take a very long time for a "cloud" of dark matter particlaes to reach thermodynamic equilibrium with itself or with ordinary matter. Gandalf61 (talk) 08:27, 26 April 2012 (UTC)[reply]

thank all specially Gandalf61 . for using "electrodynamic of moving objects" we ought to know that the matter is made of hadrons ,or dark matter(for full discussion) .we need to have its properties , as its state , mass and center of mass ,internal and external reactions , radiating ,... the termodynamic relations in statistical physics strongly depends on matter properties and state ,gas liquid or solid ,and plasma mode .DARK MATTER is which one of such states ? — Preceding unsigned comment added by 78.38.28.3 (talk) 09:42, 26 April 2012 (UTC)[reply]

Since dark matter particles are not bound to one another by any electromagnetic forces, then dark matter must be a gas. On a small scale, where gravitational interactions are not significant, you could probably model it as a monatomic gas. On a larger scale I imagine you would use something like the virial theorem. Gandalf61 (talk) 09:49, 26 April 2012 (UTC)[reply]

Dark matter isn't in atomic form so it is not a gas, plasma, solid or plasma. Weakly interacting massive particles (a leading DM candidate) are more like slow fat neutrinos. SkyMachine ⁽⁺⁺⁾ 09:56, 26 April 2012 (UTC)[reply]

I don't think a gas has to be composed of atoms - see photon gas, Bose gas, electron gas. But my point was that dark matter can (on small scales) be modelled thermodynamically as an ideal gas, regardless of whether you think it is strictly a gas or not. Gandalf61 (talk) 10:34, 26 April 2012 (UTC)[reply]

It reminds me of the commercial for dawn dish soap where one drop of soap disperese a large amount of grease on the surface of the water. if you saw the grease moving away from that spot you would thing there was something pulling that grease in the direction you see it going. but actually it was the soap pushing it.165.212.189.187 (talk) 13:02, 26 April 2012 (UTC)[reply]

Something is pulling it - the surface tension of the water. Whoop whoop pull up ^{Bitching Betty | Averted crashes} 19:13, 26 April 2012 (UTC)[reply]

There you go.165.212.189.187 (talk) 19:27, 26 April 2012 (UTC)[reply]

"There you go" I can't tell which side you're analogizing for. -RunningOnBrains^(talk) 20:47, 26 April 2012 (UTC)[reply]

The most favored theory is that dark matter (DM) is the lightest supersymmetric particle. There is indirect evidence for this, e.g. from the fact that such a particle would interact with matter via the Weak interaction. This then more or less fixes the dark matter density of the universe. The smaller the annihillation cross section of DM particles, the sooner after the Big Bang it would have decoupled, leading to freeze-out at a higher temperature and in turn to a higher present day DM density. The present day DM density is consistent with DM particles interacting via the Weak interaction.

Also, the annihilation cross section is related to cross section with ordinary matter partcles, via crossing symmetry. E.g., if you take a Feynman diagram for DM-anti-DM articles annihilating into a positron and an electron, and you rotate it 90 degrees, you get a Feynnman diagram for the scattering of a DM particle off an electron. Count Iblis (talk) 19:26, 26 April 2012 (UTC)[reply]

the source of planets' atmospheres

How had planets been able to contain surrounding atmospheres?Akbar mohammadzade — Preceding unsigned comment added by 78.38.28.3 (talk) 05:54, 26 April 2012 (UTC)[reply]

Gravity. Evanh2008 (talk) (contribs) 05:57, 26 April 2012 (UTC)[reply]

Also internally generated planetary magnetic fields prevent the solar wind from steadily stripping away the atmosphere. -RunningOnBrains^(talk) 06:12, 26 April 2012 (UTC)[reply]

You can also read the question on Europa's atmosphere found above. Plasmic Physics (talk) 07:09, 26 April 2012 (UTC)[reply]

Not really. ;) Evanh2008 (talk) (contribs) 07:39, 26 April 2012 (UTC)[reply]

"Not really"? Plasmic Physics (talk) 07:46, 26 April 2012 (UTC)[reply]

I think he was refering to the other Europa NSFW section above SkyMachine ⁽⁺⁺⁾ 07:58, 26 April 2012 (UTC)[reply]

Silly me, it's already been archieved. Plasmic Physics (talk) 08:07, 26 April 2012 (UTC)[reply]

The larger the mass of the planetary body, the easier it is for the planet to hold on to an atmosphere, thus gravitational attraction is the important factor here. Compare Jupiter with Mars or Earth for instance. Earth loses its lighter gases such as hydrogen and helium where Jupiter holds on to these gases. A cold temperature helps too, Pluto keeps its atmosphere because it keeps refreezing when it gets further out in its orbit. SkyMachine ⁽⁺⁺⁾ 07:48, 26 April 2012 (UTC)[reply]

for analyzing the combination of carbon dioxide for atmosphere of planet we can result one of this reasons :

  3- 1) The gas has been absorbed from flattened primordial disk
  3-  2) The gas has been absorbed from interstellar space
  3-  3) The gas has been created from volcanic activities (as there are several high   
                    mountains in planet)
  3- 4) Existence of  any growth process (for example process which increased oxygen 
                    on earth surface  for crust oxidation and its existence in our atmosphere  
  3- 5)Our scenario that the gas has been absorbed from solar wind (the solar wind   
                   carried particles are pulled to atmosphere , the light ones such
as hydrogen  and helium cannot  remain there for their velocity :    Vrms=√3kT/m 
(Boltzmann equation)

[[source : Analytical mechanics calculations for finding main reasons for opposite rotation of Venus Author: Akbar Mohammadzade)]] — Preceding unsigned comment added by 78.38.28.3 (talk) 09:50, 26 April 2012 (UTC)[reply]

Yes, that is true. Atmospheric gas come and leave, different types of gas leave more often than others. As gravity increases, they will leave less often, but come regularly. Statistically, they will never stop leaving.

Question for anyone: as solar wind travels long distances through space, does it cool down and radiate energy away as light, while slowing down enough to be captured by the outer planets? Plasmic Physics (talk) 10:15, 26 April 2012 (UTC)[reply]

It is not right to say that they cannot remain, it is not so black and white. You can say that statistically one molecule of hydrogen or helium is less likely to remain within the atmosphere for as long as a molecule of something heavier. Plasmic Physics (talk) 10:20, 26 April 2012 (UTC)[reply]

Plasmic Physics ! please see http://www.gsjournal.net/Science-Journals/Research%20Papers/View/4000 the solar wind particles generally remain in solar system and they are cooling by synchronious radiating . the archimedian spiral of particles movement model is shown in : [[http://www.gsjournal.net/Science-Journals/Research%20Papers/View/4029 ]] — Preceding unsigned comment added by 78.38.28.3 (talk) 10:30, 26 April 2012 (UTC)[reply]

. — Preceding unsigned comment added by 78.38.28.3 (talk) 10:26, 26 April 2012 (UTC)[reply]

I cannot, I have no access to your computer. Plasmic Physics (talk) 11:00, 26 April 2012 (UTC)[reply]

Electric Field & Electric Force

Whatis the difference between electric field and electric force ? — Preceding unsigned comment added by Temesgen Mengesha (talk • contribs) 07:07, 26 April 2012 (UTC)[reply]

One is a field one is a force experienced by an electrically charged object moving in that field. Plasmic Physics (talk) 07:09, 26 April 2012 (UTC)[reply]

What Plasmic said. An electric field is something that occupies a three dimensional space, but it does not do anything as long as no charged particles are within the field. In contrast, an electric force is something that acts, and is located on a particle. In an electric field E, a particle with charge q experiences a force in the direction of the field equal to q*E. - Lindert (talk) 08:14, 26 April 2012 (UTC)[reply]

Influence of electric field on chemical equilibrium

How is expressed in formulae the influence of the electric field on chemical equilibrium in cases where this influence occurs like the dissociation of hydrogen molecule and hydrogen atom ionization? (to name a few processes pertaining to gas phase ion chemistry and also electrolytes namely effects like Wien effect and Debye-Falkenhagen effect)--188.25.241.99 (talk) 15:59, 26 April 2012 (UTC)[reply]

for how long duration of time the sun was T-tauri star

first solar system emberyo of star formed in our global cloud, was T-tauri mode of it , the question is the age of such star which changed to be modern sun?Akbar mohammadzade.

T Tauri star says they join the main sequence (which is the type of star the Sun currently is) after about 100 million years. --Tango (talk) 13:15, 26 April 2012 (UTC)[reply]

Blue glow when pulling apart a Band-Aid wrapper?

For a couple of nights, I've been putting a Band-Aid on my finger after turning off my lights for the night. I've noticed that when I pull the wrapper apart in a dark room, the wrapper glows electric blue where the adhesive that's sealing in the Band-Aid is separating. Why does it glow blue? - Purplewowies (talk) 17:19, 26 April 2012 (UTC)[reply]

Your description suggests triboluminescence. Dragons flight (talk) 17:27, 26 April 2012 (UTC)[reply]

The article for which mentions Band-Aid wrappers specifically. -- Finlay McWalterჷTalk 17:28, 26 April 2012 (UTC)[reply]

How do they make large, curved sheets of glass?

Actually, I'm not even sure how they get normal windshield to the exact shape, but my question is inspired by those staircases you see at some Apple stores. They have pieces of glass that are quite a few square meters in a perfect cylinder section. I understand how they get glass really flat, by floating it on melted metal, but how do they get those perfect curves? I'd imagine they would bend it while still hot, but how do they then support it without causing dents or irregularities? 196.210.179.55 (talk) 20:56, 26 April 2012 (UTC)Eon[reply]