Wikipedia:Reference desk/Science

Welcome to the science section
of the Wikipedia reference desk.

skip to bottom

Select a section:

• Computing
• Entertainment
• Humanities
• Language
• Mathematics
• Science
• Miscellaneous
• Archives

Want a faster answer?

Main page: Help searching Wikipedia

   

How can I get my question answered?

• Select the section of the desk that best fits the general topic of your question (see the navigation column to the right).
• Post your question to only one section, providing a short header that gives the topic of your question.
• Type '~~~~' (that is, four tilde characters) at the end – this signs and dates your contribution so we know who wrote what and when.
• Don't post personal contact information – it will be removed. Any answers will be provided here.
• Please be as specific as possible, and include all relevant context – the usefulness of answers may depend on the context.
• Note:
  • We don't answer (and may remove) questions that require medical diagnosis or legal advice.
  • We don't answer requests for opinions, predictions or debate.
  • We don't do your homework for you, though we'll help you past the stuck point.
  • We don't conduct original research or provide a free source of ideas, but we'll help you find information you need.

Ready? Ask a new question!

How do I answer a question?

Main page: Wikipedia:Reference desk/Guidelines

• The best answers address the question directly, and back up facts with wikilinks and links to sources. Do not edit others' comments and do not give any medical or legal advice.

See also:

• Teahouse
• Help desk
• Village pump
• Help manual

November 6

Al

What is Al on the periodic table -nick —Preceding unsigned comment added by 76.199.148.217 (talk) 01:00, 6 November 2009 (UTC)

Aluminium. Intelligentsium 01:01, 6 November 2009 (UTC)

Did you look for Al at Periodic table ? Perhaps Friday is not a good day for you. Cuddlyable3 (talk) 01:07, 6 November 2009 (UTC)

Based on the IP address, I think it's still Thursday for that user. -- Scray (talk) 04:51, 6 November 2009 (UTC)

Some spell it "Aluminum." Edison (talk) 04:54, 6 November 2009 (UTC)

Searching is quicker for something like this. One can put 'Al element' or 'chemical Al' or 'AL periodic table' in and have a look at the results. Or one can put in 'Periodic table' and use CTRL+F and type 'A' in the browser search box. Or one can put these search terms into google. All quite quick and well worthwhile learning. Dmcq (talk) 12:01, 6 November 2009 (UTC)

In fact I just tried 'Al' on its own in google and Aluminium in Wikipedia was the first entry returned Dmcq (talk) 12:03, 6 November 2009 (UTC)

progenitor cells

I have read a bit about using skin cells instead of stem cells, and that there has been a lot of success with this approach, it also seems as though there are a few research groups doing groundbreaking work with skin cells. Anyways, I was wondering if skin cells have or if progenitor cells could be derived from skin cells, just as they can be derived from stem cells? —Preceding unsigned comment added by 71.156.167.117 (talk) 01:39, 6 November 2009 (UTC)

The skin certainly does have stem and progenitor cells, but you are probably referring to induced pluripotent stem cells. --- Medical geneticist (talk) 02:11, 6 November 2009 (UTC)

Actually, not many people know it -but today when one is going through an accident which result with a clear cut of his/her spinal cord -an accident that ones meant one result only : clear and constant disability (usually paraplegic)-today there is a new treatment available that is regulary used in few places around the globe. This treatment involve with the insertion of stem cells to location of the injury and it must be done within 48-72 hours from the injury itself. This treatment have about 100% success. The stem cells are achived from mature epidermic cells by removing methyl groups which keep the wanted master genes unactive and later shuttering others and so we can extract from mature cells culture a culture of stem cells that will go through cellular differentiation process to become new spinal cord tissues . --Gilisa (talk) 08:14, 6 November 2009 (UTC)

Gilesa, you are no doubt describing the possible use of iPSCs or other such induced pluripotent cells to treat spinal injury, but to my knowledge this is still a theory and not a proven medical treatment. Can you provide a reference? Just because an experimental therapy is being tried somewhere does not mean it is a proven success. There has been a great deal of hype around stem cell therapeutics, with "miracle cures" being claimed by people doing rather unscientific experimental treatments. Most of the mainstream literature still uses animal models of spinal cord injury, we don't really know the long-term effects of injecting stem cells into the spinal cord, and to my knowledge there has been no convincing clinical trial in humans, otherwise this would be a mainstream therapy. Sorry, but I'm a natural skeptic and need to see the data before I'm willing to accept that what you say ("about 100% success") is correct. --- Medical geneticist (talk) 14:18, 6 November 2009 (UTC)

I have to agree with Medical geneticist. I know rather well someone who has been a paraplegic since being injured in a motorcycle accident (truck turning didn't see him) for slightly over 3 years so have some personal experience here. Stem cells have shown some promise in improving regeneration for people with spinal cord injuries; and there are places where lower levels of regulation mean that they are 'regularly' (well I mean more commonly then the occasional trial that happens in most of the developed world) tried (for a variety of things). However I'm not aware of any evidence for 100% effectiveness in preventing paraplegic and find that extremely unlikely in theory and the lack of any mention of this in most sources also makes it very unlikely. As MG said, if it was 100% effective you can bet it would be a more mainstream therapy, or at the very least there would be a lot more hype and knowledge about this. (Why would someone hide such stellar results?) I personally suspect we will one day be able treat spinal cord injuries resonably effectively (whether primarily because of stem cells or something else) although suspect (unfortunately for my friend, although he also suspects this is the case) early results will be with those with recent injuries not who have had their injuries long term and we will probably never be able to treat long term injuries as effectively. Back to the main point, many of the current trials do of course concentrate on recent injuries although looking at the sources (particularly the last two) it doesn't appear 48-72 hours is the optimal time frame currently rather 1-2 weeks. [1] [2] [3] [4] [5] [6] [7] Nil Einne (talk) 08:02, 7 November 2009 (UTC)

Well, it seems like your sources are more up to dated than me. And it also seems like a friend, who is into stem cells research, fooled me once again.:(--Gilisa (talk) 16:23, 7 November 2009 (UTC)

Stability of slopes

what is the application of stability of slopes —Preceding unsigned comment added by Nrnvgrao (talk • contribs) 03:24, 6 November 2009 (UTC)

If Slope stability doesn't answer the question, you'll have to give more information. Looie496 (talk) 03:28, 6 November 2009 (UTC)

See also "Angle of repose." Avoid slump. Edison (talk) 04:57, 6 November 2009 (UTC)

This might be handy as well: Angle_of_repose -Craig Pemberton (talk) 05:03, 6 November 2009 (UTC)

Evolution of the hinged fang?

How could the solenoglyph's fang possibly have evolved? This strikes me as a really good poe question because it's hard to think of a functional intermediate. What do you guys think? -Craig Pemberton (talk) 04:55, 6 November 2009 (UTC)

There's nothing particularly special about such a hinged tooth; other specialized teeth which seem equally striking, certainly exist. Indeed, the hinge itself doesn't involve any joints which do not have analogues in other vertebrates, its just that they evolved to bring the venom-delivering fangs into more efficient usage. One could easily envisage a series of progressively less-efficient, but still working, systems in ancestral species of such snakes. --Jayron32 07:14, 6 November 2009 (UTC)

Yes you'd expect very strong evolutionary pressure to act with even quite slight improvements in teeth. They are pretty important in the 'survival of the fittest'! Dmcq (talk) 11:20, 6 November 2009 (UTC)

(Especially in creatures with no claws or weapons of other kinds) SteveBaker (talk) 13:30, 6 November 2009 (UTC)

These hinged fangs have evolved more than once in snakes: "Folding fangs occur in two other groups of snakes. The Australian deathadders (Acantophis), though they are elapids, are solenoglyphous. Their folding-fang mechanism is very similar in appearance and operation to that of the vipers and pitvipers. The deathadders also have the body shape and ambush-hunting habits of many viperids, an excellent example of convergent evolution."[8]

The hinged fangs are moved by palatal protractor and retractors muscles, the levator pterygoidei protractor pterygoidei and retractor pterygoidei pterygoideus respectively. These muscles attach further forward on a shortened maxilla in snakes with hinged fangs, details of the anatomy here:[9] In the evolution of 'venom delivery systems' in snakes, "dental glands became modified into Duvernoy's gland, posterior maxillary teeth became morphologically specialized relative to anterior maxillary teeth, and the anterior attachment of the pterygoideus muscle moved anteriorly, placing it in close association with the posterior maxillary teeth or fangs."[10] Basically, the development of fangs, hinges and venom just made innovative use of existing anatomy. Fences&Windows 19:17, 6 November 2009 (UTC)

Difference between airport and aerodrome

what is diffrent between airport and aerodrome? —Preceding unsigned comment added by 80.191.114.227 (talk) 07:03, 6 November 2009 (UTC) —Preceding unsigned

_{I have reformatted the question Richard Avery (talk) 07:12, 6 November 2009 (UTC)}

In the Canadian regulations [11], an aerodrome is "Any area of land, water (including the frozen surface thereof) or other supporting surface used, designed, prepared, equipped or set apart for use either in whole or in part for the arrival, departure, movement or servicing of aircraft and includes any buildings, installations and equipment situated thereon or associated therewith." An airport is an aerodrome certified to conform to certain regulations with respect to "obstruction surfaces, physical characteristics, marking and lighting, which have been recorded in an Airport Operations Manual, and Airside Operating Procedures." (from above link). So basically, all airports are aerodromes, but only some aerodromes are airports. (I believe this also is the same under international rules). -- Flyguy649 ^talk 08:26, 6 November 2009 (UTC)

An airport - is a port - just like a shipping port - someplace where goods and people come in and out of a state or country. An airfield is some place where you can land and take off with aircraft - perhaps just for joyrides or local traffic. Generally, airports have customs and immigration facilities but airfields don't. Wiktionary says that in British English, an aerodrome has to have those things too so an aerodrome is an airport - but in Australian and Canadian English, it means the same thing as an airfield. I've never heard an American use the word and it's unclear what it means in American English. The word is pretty archaic though - I'd stick with "airfield" and "airport". SteveBaker (talk) 13:28, 6 November 2009 (UTC)

In British English, aerodrome is somewhat archaic and little used. We would tend to use airport and airfield as above. --Phil Holmes (talk) 15:12, 6 November 2009 (UTC)

Here in the USA, the only time I've heard the word "aerodrome" used seriously is to refer to Old_Rhinebeck_Aerodrome. APL (talk) 06:45, 7 November 2009 (UTC)

Only an "international airport" would have customs and immigration, a ordinary domestic airport wouldn't. Rmhermen (talk) 14:40, 6 November 2009 (UTC)

strength of a C-C bond

From the carbon-nitrogen bond article: "The bond strength in a CN bond is higher (184 kcal/mol) than that of the CC bond (145 kcal/mol) [2]".

Is it talking about a C=C double bond? I thought the strength of a C-C bond was around 82 kcal/mol. John Riemann Soong (talk) 08:38, 6 November 2009 (UTC)

I would remove the line from the article altogether, since it is highly a highly ambiguous statement. If you want to make an apples-to-apples comparison, see [12]. The data is in kJ rather than kcal, but it looks like a C-C bond is stronger than a C-N (though the C-N bond is shorter); however the C=C bond is weaker than the C=N bond, and the C≡C bond is weaker than the C≡N. I would use that source and fix the article to be less ambiguous. The source in the article NOW is simply the CRC Handbook, and while I have a copy of said Handbook, I'm not going to leaf through 1000 or so pages of tiny writing to try to find where that particular editor found that particular nugget and see what he really meant. I would just use the new, unambiguous source and fix the article. --Jayron32 16:49, 6 November 2009 (UTC)

Camphire in singapore

can you find camphire in singapore —Preceding unsigned comment added by 218.186.12.230 (talk) 10:09, 6 November 2009 (UTC)

Camphire is (I believe) Lawsonia inermis - or more commonly Henna. Our article says "It is native to tropical and subtropical regions of Africa, southern Asia, and northern Australasia in semi-arid zones." - which suggests that it could probably be found in Singapore. It seems that Henna dye is used extensively in Singapore for tattoos - but, I couldn't find anything that definitely says that it grows there. SteveBaker (talk) 13:19, 6 November 2009 (UTC)

Henna seems to grow in Malaysia,[13] like Steve I can find nothing about it growing in Singpore. Henna is sold and used in Singapore though. Fences&Windows 18:42, 6 November 2009 (UTC)

sulfuryl chloride: how does it replace a C-OH bond with a C-Cl bond?

Apparently this is what happens in the production of sucralose... I struggle to get a mechanism because all the bond energies seem disfavourable (C-O is stronger than C-Cl; O-H is stronger than O-Cl). In fact, most favourable seems to be chlorination at a hydrogen atom site ... I know it is by a free radical mechanism. What generally happens when a halogen and an alcohol group are on the same carbon atom? I get the feeling that one pushes the other out...John Riemann Soong (talk) 10:10, 6 November 2009 (UTC)

The article Sulfuryl chloride does discuss the process, if not the mechanism, of sulfuryl chloride as a chlorinating agent. Since the molecule is itself somewhat unstable, and will over a relatively short time (days/weeks) spontaneously decompose into sulfur dioxide and chlorine I suspect that the reactive compound in this case is NOT the sulfuryl chloride, rather the actual reactive bit is diatomic chlorine; the sulfuryl chloride is merely a source of diatomic chlorine; being a liquid it is much easier to work with than a gas. Our article hints at this. Thus, it seems that the mechanism is a simple radical chlorination reaction; see Free radical halogenation. --Jayron32 16:42, 6 November 2009 (UTC)

π⁰
decay

When a pion decays into 2 photons by
π⁰
→ 2
γ
what is the energy in eV of the resulting photons?--IngerAlHaosului (talk) 10:36, 6 November 2009 (UTC)

In the rest frame of the pion, conservation of energy tells you that the total energy of the photons must be equivalent to the rest mass of the pion, and conservation of momentum tells you that the photons must have equal but opposite momentum vectors, therefore equal wavelengths and therefore equal energies. I'll let you take it from there. Gandalf61 (talk) 14:15, 6 November 2009 (UTC)

Fluid mechanics

What is the use of coefficent of discharge,coefficent of velocity and contraction? —Preceding unsigned comment added by Nrnvgrao (talk • contribs) 11:13, 6 November 2009 (UTC)

These are empirical factors to account for the first-order deviation between theoretical and actual values of the discharge, velocity, and contraction of a fluid. See flow coefficient. Nimur (talk) 13:51, 6 November 2009 (UTC)

GRAVITATIONAL RED/BLUE SHIFT

210.212.239.181 (talk) 12:43, 6 November 2009 (UTC)HARSHAGG

ALSO is there gravitational blue shift. Now consider light coming out perpendicular to surface of earth then graviton moving at c can't interact with light so no red shift can observe. Is this feasible because I can't find solution to this they just use classical concept of potential energy(classical in sense the one i know if there exist another concept i am not aware of

210.212.239.181 (talk) 12:38, 6 November 2009 (UTC)HARSHAGG HI I was reading the page on black hole and came across that when charge say +ve go inside black hole then applying gauss law there should be electric field but no photon can come out of black hole so no electromagnetic interaction can be there but it happens. This question is unanswered I contact my teacher they also don't know about this.

We have an introductory article on charged black holes. Needless to say, the mathematics to describe the behavior is extremely complicated; there is a quick description of the double event horizon. It is speculated (by prominent scientists in the field) that electrostatic repulsion would prevent such a charged black hole from forming naturally. Nimur (talk) 13:57, 6 November 2009 (UTC)

The electromagnetic field of a charged black hole comes from the charged material that collapsed to form the black hole, before it crossed the event horizon. It doesn't come from beyond the event horizon—any change in the distribution of charge inside the event horizon has no effect on the field outside. The same is true of the gravitational field. These are sometimes called "fossil" or "relic" fields. If you're wondering why the field doesn't redshift out of detectability, well, it turns out that fields don't work that way. I don't truly understand why.

I don't know how to explain this in terms of virtual particles. Probably it's a bad idea to think about it in those terms. The theory objectively predicts that nothing that happens inside the event horizon affects the field outside, so any explanation that claims that "virtual particles can escape the event horizon" will have to ensure that those virtual particles don't have any observable effect on the outside, so they might as well not have escaped the event horizon at all. -- BenRG (talk) 16:32, 6 November 2009 (UTC)

210.212.239.181 (talk) 04:29, 9 November 2009 (UTC)Harshagg Thanks for making me understand the basic concept of charged black hole. Can someone help for the concept of no red shift when coming normal to gravitational field

Infinite differential method

what is the use of infinite differntial method in solving problems in physics? —Preceding unsigned comment added by Snehrajravi (talk • contribs) 16:59, 6 November 2009 (UTC)

Bird bones

I have two bird bones. They are a left and a right. They are not long bones. I do not know what they are! They look sort of like two tiny femurs with broad, triangular bases and a prong sticking out just above the broad base. One of the points of this base has a round hole in it. They aren't in my avian osteology book and I can't find them through googling pictures of bird bones. Help? 138.192.58.227 (talk) 17:13, 6 November 2009 (UTC)

Identification would be easier if you could photograph them and upload the photos to a Flickr or Photobucket account, and link to the photos from here. Comet Tuttle (talk) 18:38, 6 November 2009 (UTC)

Yeah -- definitely take a photo. There is already a lack of proper communication, as you state they appear as 'femurs' yet assert they 'are not long bones.' The femur is a long bone, and if you were using 'long' as a mere adjective (and not referring to the aforementioned link), how long do you expect a bird's bone to be anyway...sort of subjective to the extreme. DRosenbach ^{(Talk | Contribs)} 19:56, 6 November 2009 (UTC)

I suppose they could be long bones (and yes, I do now what it means. I was thinking they were more like vertebrae or carpals in type). They have a similar shape to femurs but are not - I have the femurs i.d.'d already. They are femur-like on the ends, but are nowhere near long enough, as I have the bird's femurs (and humeri, etc.) already. I know I probably should take a picture, but I can't. 138.192.58.227 (talk) 17:28, 9 November 2009 (UTC)

How do you know they're bird bones? Assuming that they are, and that they don't look like what's in your textbook, the thing to consider is how easily bones can be shaped to suit different circumstances (i.e. adaptive radiation). Examine the bones and try to identify points of attachment, etc. and look through your book for bones which have the same kind of pattern, if not necessarily the same shape. The femur of a crow, for example, will look wildly different from the femur of a heron in terms of shape, but the basic pattern of structures will largely be the same. Matt Deres (talk) 04:38, 8 November 2009 (UTC)

The book has examples of a wide variety of bird species. These look nothing like any of them. The book is also missing a few other bones that I was able to identify. I know they are brid because of the look and texture, and also because I know they came from a bird - I didn't just pick up some random parts. 138.192.58.227 (talk) 17:28, 9 November 2009 (UTC)

Emission spectra

I understand which wavelengths can be emitted by a given element, but not where you can calculate (rather than observe) the percentage of each type of photon emitted. Clearly, you can observe this, and I would imagine it is governed by a probability system. Have we (that is, the scientific community) worked this out yet? In short, can you calculate the total colour (i.e. the apparent colour) of a given element, not just which frequencies it's made up of? - Jarry1250 ^{[Humorous? Discuss.]} 17:17, 6 November 2009 (UTC)

I'm not sure what you mean. The only way you could calculate the wavelengths of light emitted by an atom absent of making any measurements is via the Rydberg formula; however that only applies to the Bohr model atoms, i.e. 1-electron atoms (H, He⁺¹, Li⁺², etc.) For any atom with more than one electron, you have an n-body problem, and no simple algebraic function can be written to predict the wavelengths emitted by such atoms; you can only observe the wavelengths, not mathematically predict them as with the Rydberg formula. --Jayron32 18:35, 6 November 2009 (UTC)

I think the question presumes that you already know the wavelengths of an element's emission lines. How do you determine the relative strength of each line (and hence the visual appearance of the emission)? The answer will depend on various factors (temperature, density, incident radiation). How well can we predict the line strengths given the circumstances? -- Coneslayer (talk) 19:34, 6 November 2009 (UTC)

Color is a complex phenomena that is hard to quantify; there are many methods of plotting color in various multiple dimensions, for example. While we can quantify a single wavelength of light as a certain value, to "quantify" a bulk color made up of many wavelengths with a series of values is a difficult thing to do. Color is really about perception and not quantification. Consider, for example, that the color we call "yellow" could be made of a single wavelength OR it could be made of mixture of multiple wavelengths of light, and yet our mind would find two such colors indistinguishable; that is our color perception equipment in our minds cannot distinguish between coherant light of a single wavelength or a color made of an average of wavelengths.

As far as determining the bulk color of an excited substance; that's easy. Just look at the color before the light is passed through a prism. Emission spectra still require a prism or diffraction grating to seperate the wavelengths into an actual spectrum, so if you want to know what color such a spectrum would make if mixed together, just look at the light before it passes through the prism! --Jayron32 19:58, 6 November 2009 (UTC)

You're talking about observations, which the OP is specifically not interested in. He's asking about predicting the emission spectrum (line strengths, not just wavelengths) from physical principles. -- Coneslayer (talk) 20:04, 6 November 2009 (UTC)

See below by Coneslayer. That's the whole point, for atoms with more than one electron, you have an n-body problem which is almost imposible to predict via mathematics. It's been done for hydrogen and helium, and those required some rather complex modeling and some serious computing power. Once you get to atoms like, say, Carbon, with multiple electrons in multiple ground state orbitals, the system is just way too chaotic to even attempt a prediction. We can observe the light coming off, but we cannot predict a priori knowing only the ground state energy levels, what anything about the spectrum (wavelength OR intensity) --Jayron32 02:57, 7 November 2009 (UTC)

Thanks for the pointer. That Coneslayer guy is pretty sharp. -- Coneslayer (talk) 04:00, 7 November 2009 (UTC)

Here is one code to model emission spectra for astrophysical sources: CLOUDY. The references in the "Predicted intensities of hydrogen and helium lines" section of the FAQ may be helpful. I think the short answer is that even for relatively simple atoms, "it's hard". -- Coneslayer (talk) 20:10, 6 November 2009 (UTC)

(reply to all). Thanks. Coneslayer is right about what I meant, and your answers are very helpful. - Jarry1250 ^{[Humorous? Discuss.]} 11:38, 7 November 2009 (UTC)

For details about the necessary calculations you should look into time-dependent perturbation theory; in principle, using an appropriate oscillating potential (= perturbation Hamiltonian), you are able to calculate the time evolution of an eigenstate of the unperturbed system, and therefore the probability that a transition to a particular other eigenstate has occurred after a given time period. That will tell you something about absorption and stimulated emission. For really understanding spontaneous emission you need quantum electrodynamics; there is an approximation here (by the way, besides dipole transitions from the formula, there are higher-order transitions: quadrupole radiation etc.). Icek (talk) 11:08, 8 November 2009 (UTC)

5-membered dioxane formation from a sugar

Help! I don't know how a diol on a straight-chain sugar is supposed to form a 5-membered heteroatom ring ... basically the alcohol oxygens are geminal ethoxy atoms on a propyl chain, (but vicinal diols on the sugar chain) ... John Riemann Soong (talk) 18:22, 6 November 2009 (UTC)

Ring closure in sugars is a type of hemiacetal or hemiketal reaction, see also Furanose which is the 5-membered ring of which you speak. --Jayron32 18:28, 6 November 2009 (UTC)

Ummm, how do I put this protecting group on? Googling is so frustrating! It's not a ring closure via the carbonyl -- it's an extra protecting group that gets put on the secondary alcohols; the carbonyl and the primary alcohols remain untouched. John Riemann Soong (talk) 18:31, 6 November 2009 (UTC)

It's also a dioxane ... that is there are two ethoxy oxygens in this ring. The sugar backbone is straight-chained. HELP! I'm going to die in 3 hours! John Riemann Soong (talk) 18:33, 6 November 2009 (UTC)

You're going to have to provide more details. Do you have the complete problem you are trying to solve? I cannot help you without more information. If this is a homework problem (like a total synthesis problem) or something, we're going to need the exact wording so we can steer you in the right direction. Full structures and stuff would also be helpful. --Jayron32 18:37, 6 November 2009 (UTC)

Apparently it's called an acetonide --- but all we have on the subject on acetonides is how they're used as drugs?!! John Riemann Soong (talk) 18:38, 6 November 2009 (UTC)

Here it is ... I have to start with a sugar. Apparently I have to put these protecting groups on ... then I can oxidise the alcohols and ketones into carboxylic acids (or acid chlorides...?) The problem is that the protecting groups are sensitive to acid so acid-catalysed esterification after that might be an issue. John Riemann Soong (talk) 18:41, 6 November 2009 (UTC)

The protecting groups in this case are acetone ketals. Normally, you protect a ketone by using something like Ethylene glycol to form the cyclic ketal; however the reverse is perfectly valid, you can do a protection of vicinal diols by using a simple ketone, like acetone. That is all that is done here. Look up the mechanism of ketal protection of ketones, and its the exact same mechanism for forming the groups in that molecule. It's basically a ketal protection in reverse.--Jayron32 18:48, 6 November 2009 (UTC)

I really don't get how this protection works. Do you basically kick out the carbonyl oxygen and form a carbocation that the other diol can bind to? :S John Riemann Soong (talk) 18:52, 6 November 2009 (UTC)

Yes, the second OR replaces the OH (that OH being the carbonyl oxygen atom) by an SN1 reaction. DMacks (talk) 18:55, 6 November 2009 (UTC)

Also, should I put this protecting group on before I do oxidation of the primary alcohols / aldehydes...? John Riemann Soong (talk) 18:59, 6 November 2009 (UTC)

See this document and page down till you get to the section titled "MECHANISM FOR THE ACID catalyzed FORMATION OF ACETALS" It contains the full electron-pushing mechanism you seek. In YOUR case, instead of using two different ethanol molecules to form the acetal, you would be using the neighboring vicinal -OH groups in the sugar, but it is otherwise identical to that mechanism. --Jayron32 19:08, 6 November 2009 (UTC)

Age Re-Perfect Pro-Calcium L'Oréal Paris

What does "Pro-Calcium" means? I know there are some substances with the prefix "pro", but does it make any sense here? Quest09 (talk) 18:52, 6 November 2009 (UTC)

Yes, "pro-calcium" is a perfectly valid marketting term, regardless of whether there is any actual factual/scientific meaning behind it or whether or not that meaning is relevant to the context and intended purpose. DMacks (talk) 18:56, 6 November 2009 (UTC)

I suppose there is no meaning behind that, but I am not completely sure. Anyway, I don't know if it is perfectly legitime to use the name. If the intention is to make people believe the product has some advantage that it doesn't - like fixating calcium - you could have trespassed a moral barrier, even if legally it is allowed.--81.47.159.223 (talk) 19:53, 6 November 2009 (UTC)

The safest position, in the absence of any other evidence, is to assume that the marketing terms used by cosmetics manufactures are pseudo-scientific bullshit. —Preceding unsigned comment added by 86.134.115.178 (talk) 00:58, 7 November 2009 (UTC)

According to Wiktionary, we have five meanings for 'pro-' to choose between:

1. agreeing with; supporting; favoring
2. substituting for
3. earlier; prior
4. rudimentary
5. in front of

Something that 'supports' calcium is, I suppose, possible - maybe something that aided calcium uptake perhaps? Substituting for is an unlikely thing - if your body needs actual calcium, there is no substitute! Earlier than calcium?? That makes no sense. Rudimentary calcium - would be just calcium - you don't get much more rudimentary than a chemical element! In front of calcium...again, makes no sense.

So the only meaning that really makes sense is that this is something that helps calcium do it's job in some way. However, as others have correctly pointed out, cosmetics manufacturers appear to feel absolutely ZERO need to make any sense whatever - so this could mean anything. Also, this is "Pro-Calcium(tm)" - they couldn't have trademarked the name of a real chemical element - so this is evidently something they just thought up.

Loreal's own web page says that it's made of "Calcium microspheres"...but such a thing would be incredibly reactive with water - definitely not something you'd want anywhere near your face. Most likely, it's calcium carbonate - which would be chalk dust.

SteveBaker (talk) 01:55, 7 November 2009 (UTC)

L'Oreal's "Pro-Calcium" products contain calcium pantetheine sulfonate, which in vitro, anyway, reduces the amount of pigmentation in skin cells.[14] The Pro-Calcium products also contain hydroxyapatite, a calcium-containing mineral which theoretically might improve your skin's barrier functions, although I can't readily find a study that would support that claim. See [15]. Red Act (talk) 02:07, 7 November 2009 (UTC)

Buteyko method

Is the Buteyko method woo-woo? -Craig Pemberton (talk) 19:30, 6 November 2009 (UTC)

It does not sound like complete bullshit. Reading the article, it is basically physical therapy for asthma; that is training the breathing airways to remain open via deliberate intentional conditioning. Such methods sound plausible; however the article at Wikipedia also notes that the method requires dedication and committment on the part of the patient; so it may be possible that the method may not have as good of an outcome across a wide spectrum of patients, especially since some patients may not "do it right", and thus it may not work for them. The article unfortunately makes the method SOUND like bullshit, even if it is scientifically valid, since it uses such known bullshit terms like "holistic" and the phrase "There are no known negative trials" is worrysome because it does not define a "negative trial"; and I would not recognize that term in any actual scientific study anyways. So, on the face it looks like a plausible treatment for asthma, but that doesn't necessarily mean it is the best treatment for asthma. --Jayron32 19:50, 6 November 2009 (UTC)

That's the thing: it begs to be called out, but I don't see any obvious flaws. For example, these two videos are eerily similar in format: utter bunk and a Buteyko seminar. Both are overly confident, cite a bunch of science they don't understand, ask the audience leading questions, etc. I'm just worried that the articles on stuff like Bohr effect seem legit only because they've slipped by the notice of most Wikipedians. -Craig Pemberton (talk) 20:33, 6 November 2009 (UTC)

After reading this discussion, I went and did some minor clean-up to the article. Nowhere but the lead mentions "holistic" and "philosophy". One can't prove a negative so I removed the un-citable sentence about "no known negative trials". =Axlq 05:32, 7 November 2009 (UTC)

Killing Viruses

We have drugs that are capable of killing fungi and bacteria pathogens, however we do not have drugs that can kill viruses. Is this because any drugs that are capable of killing viruses are also capable of killing surrounding tissue? I checked the article on nanomedicine, and it didn't mention much about using nanomachines to kill viruses. Are there any ideas to use nanomachines to kill viruses? ScienceApe (talk) 19:51, 6 November 2009 (UTC)

It's because viruses are technically not living. We have drugs that inactivate many of the processes they direct or undergo, such as antiretrovirals and protease inhibitors. And in reference to your comment about antifungals -- it's those drugs that are dangerous to surrounding human tissues, because fungi are eukaryotes and have much more similar (or identical) processes and components to humans and animals than do prokaryotic bacteria. For the most part, antifungals work to inhibit the fungi cell wall production, with many of them targeting ergosterol. Check out amphotericin B and it's terrible effects on the human kidney (hence the nickname 'amphoterrible B'). DRosenbach ^{(Talk | Contribs)} 19:57, 6 November 2009 (UTC)

I'd dispute that. Viruses are not cellular life, but that is a rather restrictive view of life. Viruses replicate, usually but not necessarily with the help of others, inherit genetic mutations, and are subject to natural selection. You can't say the same about, say, fire. Imagine Reason (talk) 16:22, 7 November 2009 (UTC)

You can dispute it all you want, but that's the biological classification. DRosenbach ^{(Talk | Contribs)} 03:28, 8 November 2009 (UTC)

Really? Last I heard, it was still a largely disputed concept. It doesn't really matter, though - viruses are what they are whether we call them "life" or not. It's not that we don't understand what viruses are so we're not sure how to classify them, it's just about the definition of the word "alive". --Tango (talk) 04:01, 8 November 2009 (UTC)

The definition of life is about as meaningful to me as the definition of a planet. It's subjected to mostly arbitrary rules and criteria so it's not really that important. Almost certainly the definition of life would have to change if we discover life on other planets anyway, or if the origin of life is finally determined. The origin of life is still an unknown so no one knows what life really is. ScienceApe (talk) 05:19, 8 November 2009 (UTC)

It seems like you had your answer, then, before you even asked the question. :) DRosenbach ^{(Talk | Contribs)} 14:54, 8 November 2009 (UTC)

As for nanomachines - we don't really have any of those that are useful for much yet. The state of the research is far to early along a very long development trail for them to be useful for anything much yet. Nanomaterials are starting to become very useful though - so we'll probably get there in the end. So for now we're stuck with much more conventional medicine. Part of the difficulty here is that for some parts of the viral life-cycle, they are nothing more than little bits of DNA that are floating around in our cells tricking them into making more virusses. At that phase in that cycle, they are inside the cell, looking and behaving just like any other chunk of DNA. That's gonna make them exceedingly hard to destroy. So while you might come up with some scheme to remove all of the virusses floating around outside of the cells - there would always be some small percentage that would be tucked away, almost impossible to reach. SteveBaker (talk) 01:36, 7 November 2009 (UTC)

Nanotech would struggle to directly "kill" a virus. According to our article, virus, viruses are typically between 10 and 300nm in diameter. That makes them about the same size as nanotech. The difficulty of doing anything directly to viruses is why we use things like the protease inhibitors mentioned above - they stop the infected cells producing more viruses rather than doing anything to the viruses themselves. --Tango (talk) 01:45, 7 November 2009 (UTC)

Doesn't our immune system destroy viruses? How do they destroy viruses? ScienceApe (talk) 03:41, 7 November 2009 (UTC)

Things like Cytotoxic T cells will kill cells infected by viruses. I'm not sure the immune system does anything to directly kill viruses. --Tango (talk) 04:45, 7 November 2009 (UTC)

Also, things like antibodies or immunoglobins are used by the body to tag viruses for cleanup by other methods, but this again doesn't "destroy" the virus, it merely identifies the virus for cleanup by T-cells. --Jayron32 05:34, 7 November 2009 (UTC)

What does cleanup by T-cells mean exactly? How does it clean it up? ScienceApe (talk) 18:23, 7 November 2009 (UTC)

See my link - the T-cells kill the cell containing the virus, thus preventing the virus using that cell to reproduce. --Tango (talk) 19:30, 7 November 2009 (UTC)

I know I already looked at it. I thought he meant something else by "clean it up" since you already mentioned that the T-cells kill infected cells. ScienceApe (talk) 20:32, 7 November 2009 (UTC)

Ah, I don't think so. I think he was just explaining that there is more to the immune system's response to viruses than the T-cells I mentioned, and he's absolutely right. --Tango (talk) 20:45, 7 November 2009 (UTC)

And, since no one seems to have bothered, we do have an article, or rather subsection, on this, see Virus#Host defence mechanisms

effeminacy

What is the medical term for males who are effeminate but do not desire to have sex with other males but rather with females? 71.100.0.254 (talk) 20:22, 6 November 2009 (UTC)

That doesn't sound like a medical condition. Why do you presume that there should be a medical term for it? -- Coneslayer (talk) 20:35, 6 November 2009 (UTC)

This isn't considered a medical condition. You could call such people "effeminate heterosexual males" if you were obsessed with the taxonomy of gender and sexuality. Hey, Gender taxonomy is an article on Wikipedia, though it seems to be mostly about hermaphrodites and not what the OP was asking. Comet Tuttle (talk) 20:50, 6 November 2009 (UTC)

It isn't the same thing but some reference from metrosexual might get what you want. Dmcq (talk) 20:57, 6 November 2009 (UTC)

Yes, that is what I was thinking. --Mr.98 (talk) 21:59, 6 November 2009 (UTC)

It may be a medical condition, some type of intersexuality. Rmhermen (talk) 23:43, 6 November 2009 (UTC)

There may be evolutionary advantages in harem species for the effeminate males to sneak around the dominant males. Imagine Reason (talk) 23:55, 6 November 2009 (UTC)

I seem to recall that a species of cuttlefish does something like that. While the big males are fighting to figure out who gets the female, a scrawny male changes his color to look like a female, slips past them, mates with the female, then skedaddles before they catch on. StuRat (talk) 06:38, 7 November 2009 (UTC)

Interesting idea, but if this success happens with any regularity wouldn't it alter the male cuttlefishes' mating behaviour. The successful male would pass on, through his genes, the successful strategy. Richard Avery (talk) 11:13, 7 November 2009 (UTC)

There seems to be a limiting factor: If too many scrawny males use this strategy, then the big males catch on and watch for this, and the "effeminate" strategy no longer works. StuRat (talk) 13:45, 7 November 2009 (UTC)

I concur with your hypothesis. As a 'man's man', it aggravates me to the core to see flagrantly effeminate males on TV. It strikes me as a great big desperate ploy and a cheapening of one's birthright. Vranak (talk) 14:45, 8 November 2009 (UTC)

"Gay men who exhibit feminine traits may be at particular risk from men whose masculinity is threatened."[16]. Also, "the most significant influence on negative reactions toward effeminacy in males is homophobia (p<.001) and for male participants, benevolent sexism (p=.004)."[17] Fences&Windows 20:57, 8 November 2009 (UTC)

Ooh, a scientific study. It must be true! Vranak (talk) 21:40, 8 November 2009 (UTC)

This is a science reference desk. If you want to complain about effeminate men, go find a forum. Fences&Windows 20:42, 9 November 2009 (UTC)

Well, it depends on what you define as regularity. Cheating is stable in a mostly honest environment because the cost to the honest party is not death. It is evolutionarily stable as long as the effeminate males are not caught in their first attempts. Imagine Reason (talk) 14:03, 8 November 2009 (UTC)

I've had friends who are sometimes mistaken for gay because of their perceived effeminacy - what they seem to have in common is that all have been brought up by their mothers - I presume their epicenity stems from the fact that their primary role model was female. Adambrowne666 (talk) 13:20, 7 November 2009 (UTC)

To briefly address the original question, don't be silly, of course being effeminate isn't a medical condition. There's an interesting looking article on 'feminine heterosexual men' here, but I've not got full access. On a slight tangent, men with more feminine faces are judged as being more attractive,[18], and women prefer more feminine-looking men as long term partners, though tend more towards masculine-looking men for short term partners and when ovulating:[19]. Fences&Windows 20:57, 8 November 2009 (UTC)

While being a feminine male isn't always a sign of a medical condition, it sometimes is, typically in conjunction with other symptoms. For example, this could be a symptom of Klinefelter Syndrome. StuRat (talk) 01:06, 9 November 2009 (UTC)

Good point. There's a good discussion of how Klinefelter's affects physical appearance, behaviour and personality here . Fences&Windows 20:51, 9 November 2009 (UTC)

Adam, your observation of effeminate men being brought up by their mother doesn't seem to tally with some 23-year-old research on extremely effeminate boys that "found no evidence that the parents "created" feminine boys":[20] Fences&Windows 21:16, 8 November 2009 (UTC)

That study doesn't very directly address Adam's hypothesis. Most (3/4) of the boys in that study were gay, and of the small number (11-ish) of straight boys in the study, it isn't even reported what fraction if any of those boys were raise solely by their mother. There isn't enough information there to make any conclusions about whether straight boys who are raised solely by their mothers wind up behaving more effeminately. My presumption is that gay boys are pretty much born that way, so I see that as a completely separate issue. Red Act (talk) 03:33, 9 November 2009 (UTC)

Put another way, my perspective of the study is that it shows that the most common cause of effeminate behavior in boys is being gay. But there isn't enough information in the study to make any conclusions about what the second most common cause of effeminate behavior in boys is. Red Act (talk) 04:00, 9 November 2009 (UTC)

Sure, I didn't look for research looking at that directly. Here's a very non-scientific look:[21], and here's some studies: "The female-headed families were found to be similar to the traditional families on a range of measures of quality of parenting and young adults’ psychological adjustment. Where differences were identified between family types, these pointed to more positive family relationships and greater psychological wellbeing among young adults raised in female-headed homes."[22] "The children’s social and emotional development was not negatively affected by the absence of a father, although boys in father-absent families showed more feminine but no less masculine characteristics of gender role behaviour."(my emphasis)[23] "In father-absent homes, mothers' tendency to rely on and pressure their daughters fosters relatively more masculine girls, whereas a lack of father socialization fosters less masculine boys."[24] There's some more on the socialization of gender personality here. Fences&Windows 20:42, 9 November 2009 (UTC)

Floor Stain (help!)

A couple nights ago I dropped my Drinking Bird, the glass broke and the contents ( red dye in Dichloromethane ) splashed on my kitchen floor which I assume to be made of Linoleum. I have been unsuccessul in removing the stains, having tried various caustic cleaners, petroleum based removers and even 30% Hydrogen peroxide. Is using pure Dichloromethane my only hope? I know the chemical has probably melted or fused itself with the plastic floor. Thanks for any suggestions. cheers, 10draftsdeep (talk) 20:29, 6 November 2009 (UTC)

Our article says it is miscible with many organic solvents, so the petroleum based removers were probably along the right lines. Have you tried things like white spirit or acetone (nail varnish remover)? --Tango (talk) 20:49, 6 November 2009 (UTC)

Not yet. Thanks, I'll try some acetone.10draftsdeep (talk) 20:58, 6 November 2009 (UTC)

Be careful, though: organic solvents (such as acetone) will dissolve plastics. Test whatever you're using on an out-of-the-way corner first. --Carnildo (talk) 21:42, 6 November 2009 (UTC)

Indeed - that applies to any cleaner, but I should probably have said it anyway. --Tango (talk) 22:08, 6 November 2009 (UTC)

Will do. Although it appears the Dichloromethane has already removed the top layer of the floor's surface where it landed. Ultimately ,I am starting to think some new flooring may be the final solution.10draftsdeep (talk) 21:49, 6 November 2009 (UTC)

Also, if you're planning on using large quantities of acetone, be sure the area is well-ventilated. If it's cold where you are, wait until the hottest part of the day and put a coat on, then open some windows and use the acetone. StuRat (talk) 06:35, 7 November 2009 (UTC)

Why not dissolve bleach into a non-aqueous solvent? The problem I think is that your cleaners are all aqueous-based, and CH2Cl2 is non-aqueous. John Riemann Soong (talk) 16:27, 9 November 2009 (UTC)

calculating the pH of a solution with a polyprotic amino acid

Let's say I have an amino acid (not a biological one -- say it's 4-aminobenzoic acid with two pKa's: 2.50 at the +1 state and 4.87 in the +0 state... let's say the concentration is 0.1M. How do I calculate what the pH of the solution will be? Do I use the isoelectric point? John Riemann Soong (talk) 20:44, 6 November 2009 (UTC)

I'm trying to come up with an equation ... can someone help me. So basically the neutral compound can be deprotonated ... and protonated.

$K_{a1}+K_{a2}=({\frac {{\{AH\}}{\{H^{+}\}}}{\{AH_{2}^{+}\}}}+{\frac {{\{A^{-}\}}{\{H^{+}\}}}{\{AH\}}})$

$K_{a1}+K_{a2}={H^{+}}({\frac {\{AH\}}{\{AH_{2}^{+}\}}}+{\frac {\{A^{-}\}}{\{AH\}}})$

I get stuck around here. I'm trying to some "proton accouting" equations, but I can't wrap my head around it. It would be really nice if there were some way to determine the ratio of AH2+ to A-! John Riemann Soong (talk) 00:08, 7 November 2009 (UTC)

With some further rearranging, I get equations like: $K_{a1}+K_{a2}={H^{+}}({\frac {\{0.1\}-{A^{-}}}{\{AH_{2}^{+}\}}}+{\frac {\{0.1\}-{AH_{2}^{+}}}{\{AH\}}}-2)$

(0.1 is my concentration of my reagent.)

Is an equation like A- + H+ = 0.1 valid here? John Riemann Soong (talk) 00:21, 7 November 2009 (UTC)

Think about what the 0.1 M is actually measuring. Usually it's referring to the non-proton/non-hydroxyl portion, and to all of the forms, that is [A^-] + [HA] + [H₂A⁺] = 0.1 M. Usually in these situations defining lots of variables (e.g. [A^-] = h; [HA] = i, [H₂A⁺] = j; [H⁺] = k; etc.) and falling back on algebra in a system of simultaneous equations to find the quantity of interest is a straightforward, if inelegant, approach. -- 128.104.112.237 (talk) 00:26, 11 November 2009 (UTC)

November 7

Name that chemical

When I started working here in the semi-conductor manufacturing business, I was told of a chemical that wouldn't harm skin if the skin came in contact with the chemical. What would happen though, is that the chemical would soak into the tissue and settle in the person's bones and that's where it would cause considerable pain. I've looked it up before but it's been years. Can anyone remind me what this chemical is? Dismas|^(talk) 05:58, 7 November 2009 (UTC)

Hydrofluoric acid. Truthforitsownsake (talk) 06:19, 7 November 2009 (UTC)

Sounds a lot like benzene. Benzene causes bone marrow damage, can be absorbed through the skin,[25] and is used in the semiconductor industry.[26] Red Act (talk) 06:31, 7 November 2009 (UTC)

Thanks for the info about benzene but hydrofluoric was the one I was thinking of. Thanks, Dismas|^(talk) 11:35, 7 November 2009 (UTC)

is it possible I received permament eye damage from briefly handling apple's laser mouse at an Apple store.

This question has been removed. Per the reference desk guidelines, the reference desk is not an appropriate place to request medical, legal or other professional advice, including any kind of medical diagnosis, prognosis, or treatment recommendations. For such advice, please see a qualified professional. If you don't believe this is such a request, please explain what you meant to ask, either here or on the Reference Desk's talk page.

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

This removal is discussed here. -- Scray (talk) 14:18, 8 November 2009 (UTC)

Taxonomy

Could please someone provide the taxonomic name of these flowers? Thanks in advance! -- Etienne (talk) 13:55, 7 November 2009 (UTC)

Wow, a botany question that I can actually answer -- the first time ever! The first one looks like common madia, better known as tarweed. The picture in the common madia article doesn't look the same, but I think I'm right, it's a pretty common flower here in the Bay Area. (If not common madia, then some other type of madia, there are a ton of them.) I don't know what the second one is. Looie496 (talk) 17:31, 7 November 2009 (UTC)

The second one is cosmos_bipinnatus, I also have some doubts that the first is common madia. Richard Avery (talk) 18:44, 7 November 2009 (UTC)

Thank you! -- Etienne (talk) 18:29, 10 November 2009 (UTC)

Is lightning a spark?

Arguing definition is fun! Vimescarrot (talk) 15:59, 7 November 2009 (UTC)

Slow-motion footage of lightning (Please don't embed 2MB animated GIFs to the Ref Desk... some of us don't have the fastest connections and it screws up the whole page. Changed from embedded image to link... --Mr.98 (talk) 18:13, 7 November 2009 (UTC).)

As fun as it may be, the ref desk is not a chat room or a place for debates. Though I don't see what there is to argue about: see Electrostatic_discharge#Sparks. —Akrabbim^talk 16:26, 7 November 2009 (UTC)

Yes. Both "lightning" and "sparks" are essentially electrostatic discharges. The only significant difference is perhaps that of intensity: lightning is actually an electric arc, while a "spark" technically need not "plasma-ize" the air it passes through (apparently, at least according to the intro of the Corona discharge article...).

In any case, according to Electrostatic discharge#Sparks:"Perhaps the best known example of a natural spark is a lightning strike."

Wikiscient 16:36, 7 November 2009 (UTC)

I saw the discharge article, but wanted to check with you to make sure the article was right. Sorry, I didn't mean to imply I wanted to spark (ha!) an argument with you; I'm arguing with someone else. Thanks for the responses. Vimescarrot (talk) 16:43, 7 November 2009 (UTC)

Well in that case, argue your heart out! —Akrabbim^talk 16:49, 7 November 2009 (UTC)

I think the best way to look at it is: lightning is a "spark," but not all sparks are lightning... ;) Wikiscient 16:51, 7 November 2009 (UTC)

That animated GIF of the lightning is fake, right? Tempshill (talk) 19:42, 7 November 2009 (UTC)

I think it's real. And how dare people not wait for me to get to this question. SpinningSpark 21:47, 7 November 2009 (UTC)

I would love to know the detail of how it was filmed. How fast a camera is being used there? APL (talk) 00:03, 8 November 2009 (UTC)

Don't know about that gif, but Ultraslo uses 3000 FPS. That's not the only slow-motion lightning video on Youtube, and many put their FPS in their description. Vimescarrot (talk) 00:31, 8 November 2009 (UTC)

We used cameras (and camera-like devices) with frame rates as high as 15,000 frames per second, to record lightning and lightning-related transient luminous events. Often, these high-data-rate optical devices needed electronic triggers to activate them and initiate a burst-mode recording. Nimur (talk) 03:57, 8 November 2009 (UTC)

Ben Franklin's and others' research in the 1750's indicates an affirmative answer. Edison (talk) 04:04, 8 November 2009 (UTC)

Torch lights

Will shining 2 torch lights into a particular area make the resulting light brighter? Clover345 (talk) 17:37, 7 November 2009 (UTC)

Yes. It won't, however, make it look twice as bright. The human eye perceives brightness logarithmicly, that means doubling the actual brightness (by shining twice as much light at it) will make it look a fixed amount brighter (ie. it will add something to the brightness rather than multiply the brightness by 2). See Weber–Fechner law#The case of vision. --Tango (talk) 18:05, 7 November 2009 (UTC)

Also, don't forget interference (as shown by Young's slit experiment. Shutting off a light in the room will lower the overall amount of light in the room, but the areas that were previously in the interference path of multiple light sources might actually get brighter. John Riemann Soong (talk) 23:11, 7 November 2009 (UTC)

That's a really terrible answer! Do you have any idea how narrow those interference regions are? No! Of course you don't or you'd never have said that. You'd need a microscope to see them. Where are these "slits" that are necessary for the effect to work? Do you realize that flashlight bulbs or flashlight LED's are not point sources - and they aren't monochromatic and they aren't coherent? Have you ever heard of diffuse scattering? A little knowledge is a dangerous thing! It is absolutely not the case that turning on a second flashlight will make any measurable part of the room measurably darker. Your answer is confusing and flat out incorrect. Tango had it right - the end. SteveBaker (talk) 23:48, 7 November 2009 (UTC)

Well deserved thanks to our bright knight for saving this answer! DRosenbach ^{(Talk | Contribs)} 14:59, 8 November 2009 (UTC)

Why do my glasses have a shadow?

My eyeglasses are transparent and yet when it's very bright and light is angled properly, the lenses have a shadow. Why is that? 69.77.250.210 (talk) 19:13, 7 November 2009 (UTC)

Lenses work by difraction, bending and redirecting the incident light. There is still the same amount of light hitting the lens, but because it is not going "straight through", the area straight through is not as brightly illuminated as the surrounding area that is directly illuminated. DMacks (talk) 19:26, 7 November 2009 (UTC)

It could also be because they aren't perfectly transparent. The diffraction (note spelling!) can cause some bright spots which are brighter than the surrounding area, this means the average brightness is about the same. --Tango (talk) 19:29, 7 November 2009 (UTC)

Thank goodness redirects help when my riting is not good. DMacks (talk) 19:32, 7 November 2009 (UTC)

Yes, diffraction is the answer. See also Lens (optics) and Caustic (optics). Red Act (talk) 19:45, 7 November 2009 (UTC)

My eyeglasses work by refraction, not diffraction. -- Coneslayer (talk) 20:10, 7 November 2009 (UTC)

Note as well that even in the absence of diffraction effects your lenses aren't perfectly transparent, and they do not transmit all of the light that strikes them. Depending on the material the lenses are made from, and what coatings have been applied, somewhere in the neighbourhood of 10% of the incident light is going to be reflected or absorbed. TenOfAllTrades(talk) 19:51, 7 November 2009 (UTC)

As far as I know no corrective glasses work by diffraction but rather refraction. I'm assuming the OP has myopia as my glasses do the same thing too. If you try moving it closer or further to the surface on which the shadow projects to, you can see that the shadow changes brightness and you may notice a slight ring of light surrounding the shadow. In essence myopia corrective lenses makes parallel rays of light divergent, so that if you shine a light through it the rays now have to cover a larger area, so the area directly under the lens is darker than the surrounding. Just outside this "shadow" you can maybe see a slight halo. This is the place where it receives light from both the divergent rays from the lenses and also directly from your light source. Hyperopia corrective lenses are the opposite, they're like magnifying glasses and will form a bright spot in the centre when you try the same thing. --antilived^{T | C | G} 23:13, 7 November 2009 (UTC)

Wow, that's really bizarre that four of us used the wrong word! On a multiple choice test, I'd bet all four of us would correctly answer that lenses work by refraction, not diffraction. But somehow the wrong word stuck once it entered our heads. It's like some kind of groupthink or something. Red Act (talk) 01:32, 8 November 2009 (UTC)

Yikes! Well at least I can add "able to control brains by remote control" to my CV. DMacks (talk) 18:20, 8 November 2009 (UTC)

You could be a vampire. Vampires, and their attire/accessories, don't cast shadows when they normally would, but do cast shadows when they normally wouldn't. Can you see your reflection in a mirror? 92.230.64.60 (talk) 18:18, 8 November 2009 (UTC)

All together now: Wikipedia has an article about that. Cuddlyable3 (talk) 19:33, 9 November 2009 (UTC)

Batteries in plastic bags

If I throw multiple AAA batteries or AA batteries in plastic bags, like Ziploc bags, will a circuit, however weak, be formed by means of the plastic bag touching the ends; and will the batteries deplete faster than if I throw them in a drawer, or loose in a plastic tub, or in a paper bag? Tempshill (talk) 19:41, 7 November 2009 (UTC)

I'd say there would be no noticeable difference, since plastic is essentially an insulator. That is, unless the plastic is wet. StuRat (talk) 19:46, 7 November 2009 (UTC)

A clean dry plastic bag will not complete a circuit. There is a remote possibility that a number of batteries could arrange themselves to complete a circuit. Edison (talk) 20:15, 7 November 2009 (UTC)

Yes agreed, unless the bag is an antistatic bag used for storing electronic parts. These are usually either obviously metallic or else are slightly pink. @Edison, to form a complete loop the batteries need space enough to form something like a 3-foot circle - bigger than most plastic bags, so unlikely. In the old days the negative terminal of the battery, which is also the case, appeared as a ring around the positive terminal so it was very easy to short them out. All good quality brands now have insulated cases so this can no longer happen. SpinningSpark 21:37, 7 November 2009 (UTC)

Nine-volt batteries are also very prone to being shorted if stored loosely, due to the proximity of the terminals. Mitch Ames (talk) 01:08, 8 November 2009 (UTC)

Many small cells have a steel cylinder around them, like Duracell, perhaps painted, which could complete a circuit unless the paint is a good insulator. A 9 volt is the most likely culprit to short in a bag of batteries, agreed, or any cells in a pocket with change and keys (not the same as the OP's scenario). Edison (talk) 04:03, 8 November 2009 (UTC)

I just checked with a multi-meter, I tried a AA Duracell and a AAA Walgreens, both were good insulators except at their ends. (Even though they were both visibly shiny.) I suspect that they do it like that for specifically that reason.

Incidentally, it's not paint, it's a plastic wrapper. APL (talk) 07:25, 8 November 2009 (UTC)

Yes, plastic, at least on well known quality brands. It is possible to get through it to the metal if you have sharp meter probes but you have to push hard. For this to happen accidentally in a plastic bag would require the battery to be very severely and visibly obviously damaged. Agreed 9 volt batteries are the exception here (and other rarer types with both terminals on the same side), an unprotected pocket full of them can succeed in getting hot enough to burn your skin. SpinningSpark 09:58, 8 November 2009 (UTC)

Cylindrical cells I checked all have an insulating plastic wrapper around the steel outer casing, however shiny and metallic it looks, since otherwise it would short the + and - terminals. There is an insulating fiber washer between the - terminal and the steel surround, with the wrapper covering it. However, on Duracell 9 volt batteries, there is no plactic wrapper, just painted steel. In the 9 volt, there is an insulating fiber piece at the end between the steel case and the + and - terminals, so 9 volters are a short circuit risk even if the contact is just with the outer case. The paint layer is insulating but easily scratched through. Edison (talk) 15:48, 8 November 2009 (UTC)

I took these photos of animals for WP, but I'm not sure what they all are =(

If anyone knows who any of these guys are it would be greatly appreciated and would probably help various taxa get an image! Best regards, -Craig Pemberton (talk) 21:24, 7 November 2009 (UTC)

There are 174 pictures in there. Which ones do you want identified?! It would be a good idea to post the ones you want identified as thumbnails on this page, with numbers or tags of some sort; otherwise we may not even be talking about the same picture at any given instant. Please only post the best ones. --Dr Dima (talk) 21:45, 7 November 2009 (UTC)

Those are pretty nice, but it's clear you know what a lot of them are—you're making me kind of have to wade through them all on the off-chance I will find one of the ones you don't know and then will know what it is. You could facilitate this a little bit... (And I will disagree with Dr Dima that posting all of them is probably useful, though obviously not all will end up in articles. As a graphic designer, I have gotten a LOT of use out of high-res images on Commons that were not the "best" but were well categorized. Web space is cheap! But the blurry little beetle probably isn't worth uploading.) Your photo of the convergent evolution image should not be uploaded (the substantive content is copyrighted by the museum unless otherwise indicated—taking a new picture of a copyright image does not substantially change its copyright status). --Mr.98 (talk) 21:49, 7 November 2009 (UTC)

Okay. Should I upload some to commons, and make a gallery here? Or should I just link the most mysterious ones? Is it alright to leave the convergent evolution one on Flickr? Thanks for the feedback! -Craig Pemberton (talk) 22:07, 7 November 2009 (UTC)

As I said, you should only upload the best ones; definitely not all of them!!! Sorry if that was not clear. Look for similar pictures available in Wikimedia Commons, and only upload ones that are better than the ones already found in Commons. Do not upload any of the unsharp / unclear / partially obstructed ones. Also, if you have there a picture of critter not represented in Commons at all, you can upload that, as well. That should shorten your list from 174 to anything between 2 and 20. --Dr Dima (talk) 22:29, 7 November 2009 (UTC)

To answer your question on copyright, you will be breaching someone's copyright with the poster uploaded to Flickr (except in the unlikely event that it has a free licence). That is nothing to do with Wikipedia of course, that is between you, the museum and Flckr. sorry, I do not know what any of them are - except the first one, that's a dog. SpinningSpark 10:12, 8 November 2009 (UTC)

Rechargeable batteries

I've noticed that if the battery in my DS dies and I'm somewhere where I can't recharge it, the battery will gradually build up a charge again by itself. Why is this? --70.247.249.87 (talk) 21:51, 7 November 2009 (UTC)

Me too -- my phone will show a low battery level, then suddenly go back up. I also notice that while it's charging and the battery level is say, 70%, disconnecting the charger will make it rise to 80% -- but connecting it back again will make it drop to 70%. My hypothesis is that what is happening that less of the battery capacity becomes visible to the phone after the charger disconnecs, but this hidden capacity is later "rediscovered"? John Riemann Soong (talk) 23:21, 7 November 2009 (UTC)

There is a phenomenon in many kinds of battery called "polarization" - it has the effect of causing the battery to lose power before it's actually totally dead. Turning the thing off and letting it recover for a few seconds allow you to get a little more use out of the battery. You can see this effect in all sorts of batteries and in all sorts of situation - so it doesn't surprise me that you're seeing it in your Nintendo DS. To be 100% clear though - the battery isn't "building up a charge" - it always had that charge - it just wouldn't let you use it. It doesn't matter how long you wait beyond the first few tens of seconds, you get to use that last little bit that was in the battery - and that's it. SteveBaker (talk) 23:22, 7 November 2009 (UTC) Added link to article. Mitch Ames (talk) 01:16, 8 November 2009 (UTC)

So how is it a DS which I played out of battery has twice now managed to "build up" in excess of an hours' charge? I know I haven't charged it without remembering because I lost the charger. Vimescarrot (talk) 00:14, 8 November 2009 (UTC)

For what it's worth, I've also noticed this phenomena with my DS. If I run the battery down until it shuts itself off and refuses to turn back on, and then leave it off for a while. (Ten seconds isn't enough, but ten minutes is) I can usually get at least another half hour of play out of it. Sometimes I can do this a few times before it stops working entirely. Must be a quirk of these batteries as they age. They "die" well before they're actually "empty". APL (talk) 00:50, 8 November 2009 (UTC)

I have to leave mine for days or more to get this result. Vimescarrot (talk) 01:52, 8 November 2009 (UTC)

Note the important distinction between battery is dead and control electronics have shut down the battery. The battery's life-cycle and charge cycle will cause its voltage and current capacity to vary through its usable life; the control electronics (at the very least, an LVDO regulator) will shut the entire device down until it detects that the battery is able to operate. Sophisticated battery management circuitry may even include software to estimate the chemical lifecycle of the battery (think ACPI, though the Nintendo DS probably uses a simpler scheme); so it will make a best-guess based on current measurements and expected values. When current battery measurements do not match up to the estimated values (e.g. because of manufacturing tolerances; temperature; or poor internal modeling for the estimates) unknown behavior may result (like premature shutdowns or reporting incorrect battery levels). Chances are good that the battery has enough "juice" (current-capacity and voltage) to actually operate your device, but not enough to trigger an "all-clear" from the over-zealous power regulation circuitry. When a temperature change or just a few minutes/hours of rest for the battery's chemical boost the voltage levels back above the regulated threshold, the device works fine again. My bet is that the actual voltage level didn't change by very much - but it was hovering very close to a designed safety threshold to prevent brownout. Nimur (talk) 17:05, 8 November 2009 (UTC)

Luxon theory concerning tardyons

Does Wikipedia have any information on luxon theory, specifically on their relationship to tardyons? —Preceding unsigned comment added by Active Galactic Nuclei (talk • contribs) 22:03, 7 November 2009 (UTC)

A "luxon" is a massless particle - either a photon or a gluon. Since there are no free gluons - you might as well say skip the fancy language and say "photon" instead of "luxon". Tardyon is another neologism used (rarely) to mean anything that's moving slower than light - which is to say: Everything except photons. So you're asking whether there is information on photon theory, specifically as they relate to all normal matter? Well, yes, of course! How light and other electromagnetic radiation interacts with matter? Start with Newton - work your way forwards. SteveBaker (talk) 22:28, 7 November 2009 (UTC)

A Google search for "luxon theory" only turned up www.tardyon.de, which I guess is what prompted this question. It's a crackpot site. However, it's right when it says that "tardyons are luxons". In field theory (classical or quantum) it's useful to describe massive waves as massless waves that interact with each other in a certain way. Specifically, a wave can be divided into "left-handed" and "right-handed" parts which individually propagate at the speed of light, and the mass (if any) shows up as an interaction between those parts. In the Standard Model that interaction also involves the Higgs field, which is why the Higgs is said to "give mass" to the particles. -- BenRG (talk) 23:14, 7 November 2009 (UTC)

Here was my starting point: http://en.wikipedia.org/wiki/Massless_particle. I was hoping for anything more you might have on it? —Preceding unsigned comment added by Active Galactic Nuclei (talk • contribs) 23:46, 7 November 2009 (UTC)

I removed the reference to the "luxon theory" site. I'm not sure what to add to what I and SteveBaker already said; do you have a more specific question? -- BenRG (talk) 14:23, 8 November 2009 (UTC)

The text and link that you removed were the issue, Thank you. —Preceding unsigned comment added by Active Galactic Nuclei (talk • contribs) 18:02, 8 November 2009 (UTC)

why isn't the Wolf-Kishner reduction or the Clemmensen reduction used for meth synthesis?

Bleach (sodium hypochlorite -- failing that one could fall back to Swern oxidation) and W-K or Clemmensen would seem to do the job quite nicely. No phosphine gas? Or is red phosphorus much cheaper? (This is purely out of curiosity as I reduce an alcohol to a C-H bond for the umpteenth time on paper...) John Riemann Soong (talk) 23:39, 7 November 2009 (UTC)

Bleach has its own problems, see Bleach#Chemical interactions. My guess is that most people home-brewing their own crystal meth aren't exactly familiar with various reaction pathways that get them their product. Likely one could do it safer with the right materials. But really, these guys are just following a recipe without knowing why they do each step, and what all the process is about. --Jayron32 01:24, 8 November 2009 (UTC)

Well, couldn't the amine group be protected under acidic conditions? Or is the N-H bond that reacts? Plus even if one gets a chlorinated amine, wouldn't the chlorines be relatively easy to take off in the presence of acid, seeing how chloride a good leaving group? John Riemann Soong (talk) 01:49, 8 November 2009 (UTC)

Again, you're asking why people don't follow good organic synthesis procedures when they are brewing crystal meth in their garage. The answer is because they aren't chemists; they're gap-toothed hillbillies who didn't finish the 4th grade and are following a recipe they found on the internet. People engaged in illegal activities don't often have the time and resources to do proper, standardized experiments to work out alternate pathways. They have a recipe, they follow it, they blow up their garage when they screw up. Questioning why they don't "do it right" misses the point. It was much the same with white lightning compared to legal, regulated booze. --Jayron32 02:00, 8 November 2009 (UTC)

Well 2 questions. Does bleach oxidise alcohols under acidic conditions? How do you lyse a quartenary ammonium salt? I mean, street drug syntheses often have a fair amount of pragmatics built into them -- clearly there are clandestine chemists who cooperate with gangs or new synthesis techniques wouldn't pop up now and then. John Riemann Soong (talk) 02:06, 8 November 2009 (UTC)

Bleach-oxidation borneol→camphor using acetic acid as (co)solvent is an undergrad lab experiment. Hypochlorous acid is a stronger oxidant than hypochlorite but is less stable in solution. Exact oxidizing mechanism is a bit complicated IIRC (maybe some radical character, can't remember), but it's approximately formation and then E2-like decomposition of H-C(R₂)-O-Cl similar to Swern and Cr(VI) oxidants. But this reagent mixture sounds like a perfect way to oxidize an amine→chloramine too (that's one of the reaction types that happens in swimming pools). DMacks (talk) 14:31, 9 November 2009 (UTC)

So what would prevent you from carrying out the oxidation under acidic conditions? (Add vinegar, then sodium hypochlorite?) If the amine is R-NH2+-R I would think it couldn't quite do a nucleophilic attack on OCl-. My only worry was that the acidity would prevent the alcohol proton from leaving. John Riemann Soong (talk) 14:44, 9 November 2009 (UTC)

Some people making crystal meth are chemists. Someone has to make the recipes. In fact I would think there'd be a lot of money in finding cheaper, safer and easier ways to produce illegal drugs in your basement. Rckrone (talk) 04:48, 9 November 2009 (UTC)

How should a chemist make money by creating a cheap easy method to synthezise meth? Selling the idea on ebay or publish it as a book? The only way is to do it on his own in his basement, and that is a risk a well trained person with a good job will not take.--Stone (talk) 14:42, 9 November 2009 (UTC)

There do exist circumstances that sometimes occur in people's lives, that could cause a well-trained chemist to become desperate enough to become a meth cook. The circumstances in Breaking Bad, for example, seem fairly plausible to me. There are also psychological conditions that would make some people enjoy, or at least not fear, the risks involved with being a meth cook, to the extent that they would turn to that from a career in chemistry, even without being desperate. After all, the money is great (until you get caught or die). All it would take is an underestimation of the risks involved, which is a very common thing to do, especially among younger people. Red Act (talk) 16:20, 9 November 2009 (UTC)

energy vs frequency

The articles on frequency and energy confirm the increased frequency requires or represents increased energy but where can I find a plot of energy versus frequency for both sound and electromagnetic waves and all types of vibrations from zero frequency to Gamma and Cosmic rays? 71.100.0.254 (talk) 23:46, 7 November 2009 (UTC)

For light the formula is: E=hf, where E is energy per photon, h is Planck's constant and f is frequency. That holds for any EM radiation. Cosmic rays are just particles, they aren't usually thought of as waves (although you can get a frequency from the de Broglie wavelength if you want to, in which case the same formula will hold as for light). For sound, you can't divide it into particles, so there isn't a discrete energy. There is sound energy flux (not a great article, though...), which is the amount of energy to pass through a unit area in a unit time. --Tango (talk) 00:25, 8 November 2009 (UTC)

Actually, sound felt left out of the whole "wave-particle duality" party, so it went and got itself its own sound particle. Well, sort of. But there is a particle equivalent for vibrational energy just like there is one for electromagnetic energy. --Jayron32 01:19, 8 November 2009 (UTC)

Big "sort of"! As the first line of that article says, it only applies is a solid crystal lattice. We usually think of sound as being carried by air, since that is what we can hear, and air isn't a solid crystal lattice. --Tango (talk) 02:05, 8 November 2009 (UTC)

But what about a graph... x = frequency, y = energy? 71.100.0.254 (talk) —Preceding undated comment added 01:47, 8 November 2009 (UTC).

They're proportional, so it's a straight line, and h is positive, so it goes from bottom left to top right. --Tango (talk) 02:05, 8 November 2009 (UTC)

So then hf=mc²...? 71.100.0.254 (talk) 02:39, 8 November 2009 (UTC)

Kind of. That only works if you take m as relativistic mass. The rest mass of a photon is zero. --Tango (talk) 02:43, 8 November 2009 (UTC)

In my mind it appears I was actually thinking of a curve so I must have been thing of wavelength and not frequency. Anyway the would mean that since wavelength is inversely proportional to frequency that there must be a limit on the shortness of a wavelength (the shortest possible wavelength) to equal the greatest amount of relativistic energy for every particle? 71.100.0.254 (talk) 02:47, 8 November 2009 (UTC)

Mathematically, there is no limit to how small a wavelength can be, or therefore how much energy a photon can have. However, any wavelength shorter than a Planck length is likely to be meaningless, so the universe appears to have a practical limit built in. --Jayron32 02:53, 8 November 2009 (UTC)

Somehow I'm thinking that at that wavelength something mysterious happens like the propagation in a single direction stops and you get a stationary oscillation that is self containing otherwise known as energy in the form of mass. Sort of like a cowboy rope trick where the rope spins in a loop and then the loop moves forward and backward or some such crazy back and forth but stationary relationship like that. 71.100.0.254 (talk) 03:15, 8 November 2009 (UTC)

A single photon with wavelength equal to the Planck length would have energy equivalent to about 10^-7 kg, which is much larger than any of the particles we know of that make up matter. I don't think people really know what would happen at energy levels that high. Rckrone (talk) 07:05, 8 November 2009 (UTC)

We don't know what happens at the Planck length; we don't even know if the Planck length is special at all. If special relativity is valid (locally) then photons with Planck-length wavelengths are just like any other photons. Special relativity might be wrong, but so far there's no evidence that it is. Actually, the GLAST/Fermi project recently reported data from GRB 090510 that strongly constrains violations of special relativity at the Planck length. -- BenRG (talk) 14:09, 8 November 2009 (UTC)

It's not so much that SR could be wrong, it is that it is incomplete. SR doesn't explain the fringes we see when beaming electrons or individual photons or whatever through a double slit. We know that things happen on small scales that SR doesn't explain, the question is what actually happens at those scales and how small we need to get to see weird things. --Tango (talk) 20:14, 8 November 2009 (UTC)

By SR I really meant Lorentz invariance, which holds exactly in the Standard Model. There's no evidence (yet) that Lorentz invariance fails at any length scale. The threshold where things start to look quantum has more to do with temperature than distance. -- BenRG (talk) 01:52, 9 November 2009 (UTC)

November 8

Convict Fish

In the BBC Life natural world documentary about fish there is a segment about a fish called the "convict fish", this is the clip [27] and I was trying to find out more about it and the like, however searches only ield the convict chichlids, which seem quite different and no where near as peculiar. Any idea what its taxonomical name is / any info on it? MedicRoo (talk) 01:09, 8 November 2009 (UTC)

See this page. We have an article at Pholidichthys leucotaenia, but it's not very informative. Deor (talk) 01:57, 8 November 2009 (UTC)

Nimh substitute for Nicad?

Can an Nimh battery of the same voltage and millampere-hour rating be used to replace a Nicad battery in a cordless phone? I thought not, because the charging arrangements can be different. Edison (talk) 03:59, 8 November 2009 (UTC)

Yes. I've done it many times, it works just fine. And you can (and should) use a larger milliamp rating too. Most (well, all the ones I looked at) cordless phone batteries are just AA or AAA batteries attached to a special connector. You can buy regular rechargeable AAA NiMh batteries and use them (it's a bit tough to solder - don't let the battery get hot). Ariel. (talk) 05:24, 9 November 2009 (UTC)

Kinematics Question

A rock is dropped from a seacliff and the sound of it striking the ocean is heard 3.0 s later. If the speed of sound is 340 m/s, how high is the cliff? The answer is 41 meters, but I don't know how to get it. —Preceding unsigned comment added by 174.6.144.211 (talk) 04:21, 8 November 2009 (UTC)

Call the height of the cliff h. Then work out how long it will take to fall that far (remember your constant acceleration formulae?) and how long it will take for the sound to travel that far. Then add them together and set it equal to 3 and solve for h. --Tango (talk) 04:35, 8 November 2009 (UTC)

The question is ambiguous and poorly framed because it does not specify where the listener is. The sound might well be heard by someone at the water level below the cliff, or 100 meters from the cliff in a boat, just as it might be heard by someone on the cliff. Edison (talk) 04:53, 8 November 2009 (UTC)

The question only makes sense if they are listening from the top of the cliff. If they are at the water level below the cliff it would be a trick question, since the sound thing wouldn't add anything. If they are in a boat elsewhere on the water then there isn't enough information in the question to answer it. While it would be good if the question were more precise we shouldn't over analyse things - if it is obvious what the question means then it is much better to answer it rather than pick holes in it. --Tango (talk) 05:15, 8 November 2009 (UTC)

(ec) The speed of sound is a red herring. Solve the problem assuming the speed of sound is instantaneous and see how it works out. Matt Deres (talk) 04:56, 8 November 2009 (UTC)

I assume the problem is that the correction for the error caused by the speed of sound is kind of nonlinear. If you simply subtract away the error caused and add it back to the time (say 3.12 seconds) that changes your answer and now you have to iteratively calculate your solution. John Riemann Soong (talk) 05:01, 8 November 2009 (UTC)

The additional term is absolutely not nonlinear (even though it is quadratic). Note the important difference between the meanings of linearity. Your suggestion to use an iterated approach indicates that you are confusing the definitions. This physics problem is described by a quadratic equation in time (t) (or in height h), which is (strangely) a linear equation. It is unfortunate that the word "linear" has two different meanings. The solution, though, is obtained by standard quadratic formula or as shown below by Gandalf and others. Nimur (talk) 17:14, 8 November 2009 (UTC)

That's not true. The speed of sound will make a difference. If the speed of sound were instantaneous you would get a larger value for the height of the cliff. --Tango (talk) 05:15, 8 November 2009 (UTC)

Wrong direction oops. But you might still see what I'm saying. The order of magnitude of the error looks to be around 10%, though the precise value of that error is unknown to me. (What is the error of the error?) John Riemann Soong (talk) 06:00, 8 November 2009 (UTC)

The speed of sound is definitely not a red herring, as sound moves slowly enough to make a significant impact on the solution. The speed of light, however, is fast enough to be assumed to be instantaneous in such a problem. StuRat (talk) 13:08, 8 November 2009 (UTC)

The sound is going to reach you in about a tenth of a second; just barely within the significant figures provided. I agree that you could add that to the equation, but I don't see the point if you're not going to deal with much larger factors such as the placement of the dropper/listener(s) and the drag from the air, including up-drafts - not to mention the height of the waves below. Matt Deres (talk) 20:08, 8 November 2009 (UTC)

A nice problem. Expanding on Tango's approach: If the rock takes time t1 to fall the height h and the sound takes a further time t2 to reach the top of the cliff (making the assumption that the listener is at the top of the cliff) then t1 + t2 = 3 s. Substitute expressions for t1 and t2 in terms of h and you get an equation in h and sqrt(h). Rearrange and square both sides and you get a quadratic in h. Solve and throw away a spurious solutuion introduced by squaring both sides, and you are left with a value for h that is a little under 41 m. If you assume t2 is 0, then you get 44 m, which is a significant difference. Gandalf61 (talk) 13:30, 8 November 2009 (UTC)

Or you can do it in an iterative fashion, as John Riemann Soong suggested. That makes the math much simpler, especially if you only want a couple significant figures (and, really, any more than that is spurious accuracy anyway, when someone is timing how long it takes them to hear something, which can't be very accurate). In the case of a multiple choice test, you also have the option of plugging in the values provided to see which gives you the right total time. (You might say this is cheating, but knowing how to check the answers provided by others is also a valuable skill.) StuRat (talk) 17:53, 8 November 2009 (UTC)

I would strongly recommend that technique in multiple choice tests. Trying to work out the right answer is often a waste of time, it is much quicker to just work out which of the options is right. Even if you can't narrow it down to one answer all you need to do is rule out one or two options on each question to make random guessing of the other options likely to give you a pass mark (obviously it depends on the pass mark, how many options you are given and whether marks are deducted for incorrect answers). Maths isn't usually done using multiple choice, though, since the method is usually more important than the final answer. --Tango (talk) 19:03, 8 November 2009 (UTC)

are quantised values always rational?

The cardinality of the continuum provides much more than the cardinality of the natural numbers... if the wavelength of a photon is 1500/pi nm, and a HOMO-LUMO gap of a fluorescent molecule is 1500/(pi+1/e^99) nm, will excitation occur? John Riemann Soong (talk) 05:06, 8 November 2009 (UTC)

I think the difference in length there (I haven't actually calculated it) will be less than the Planck length, which means they can be assumed to be equal. Quoting lengths at greater precision than +/- the Planck length is pretty meaningless. --Tango (talk) 05:19, 8 November 2009 (UTC)

That said, the largest difference that still allows for excitation is probably larger than the Planck length, otherwise it would hardly ever occur. I know virtually nothing about HOMO-LUMO gaps, though, so I'll have to let someone else give a more specific answer to that problem. In general though, nothing is exact in physics, so we can always choose to use a countable subset of the real numbers (eg. truncate all decimals after a few hundred places, it won't make any difference to anything - a few dozen places would probably suffice for almost everything). --Tango (talk) 05:23, 8 November 2009 (UTC)

Basically I wonder how it is possible that when I set my photoreaction chamber for say, 380 nm, how it's possible that orbital excitation ever be possible. I understand that quite a sharp distribution can be produced, but how likely is that the photons generated will ever be of the 380.0501292201285028(...) nm wavelength required for excitation? I understand that the Boltzmann distribution and random heat may kick in and provide that little more or little less of energy required to make the transition (e.g. within a certain difference environmental fluctuations can "compensate"), but then this also asks the question whether the environmental fluctuations themselves are rational. I know that a lot of time the Boltzmann distribution of molecular velocities spans such a large range of possible values that we call it a continuum -- but are those values countable? John Riemann Soong (talk) 05:53, 8 November 2009 (UTC)

There is an energy-time uncertainty analogous to the position-momentum uncertainty (Heisenberg's uncertainty principle), so a energy difference of ΔE = c*h/(1500*e^99) = 1.34E-71 J means that the "uncertainty in time" - that is, the time it takes for the transition to occur, is Δt = ℏ/(2 ΔE) = 3.94E+36 seconds. So unless your typical observing times are of that order of magnitude, you don't need to worry about such a deviation. Icek (talk) 11:47, 8 November 2009 (UTC)

And you can think of it in a different way: If you have your light source producing the light of this specific frequency for some relatively short time period (like a second, an hour or a year). The actual frequencies that the light source produces are determined by a Fourier transformation of the amplitude of the electrical field; for your frequency f, the electrical field is ideally sin(2πf t), but the light source is only turned on for a finite amount of time and has some intensity profile when being turned on and of (usually not going from zero to full intensity and back down to zero abruptly, but even if it does, my argument still applies), and therefore some function g(t) which is zero for the time the light source is turned off has to be multiplied with sin(2πf t) in order to get the real amplitude of the electrical field. Now Fourier transform the resulting function - you will get a frequency spectrum with a sharp peak at your frequency f, but the width is still far larger than the deviation in wavelength/frequency you mentioned. Icek (talk) 12:06, 8 November 2009 (UTC)

And of course, the relevant time is not the time the light source is turned on, but its coherence time, if it is shorter. Icek (talk) 12:11, 8 November 2009 (UTC)

I still have the issue of cardinality. The frequency spectrum may be treated as continuous, but are the actual elements of the spectrum rational? The number of elements must be finite: if I have a 100W bulb releasing 380 nm (ish) photons, there can only be 1.9 * 10^20 photons that are released every second. But the number of possible values near 380 nm is uncountably infinite. Why should any of those photons match my energy gap? John Riemann Soong (talk) 14:49, 8 November 2009 (UTC)

Countably vs. uncountably infinite is irrelevant here. Photons do not have a precise frequency. It's only possible to measure the frequency of a photon for some amount of time that isn't arbitrarily large. So from the Heisenberg uncertainty principle, it's only meaningful to talk about the frequency of a photon to a precision that isn't arbitrarily small. It's not like the difference between two rational numbers, which can be arbitrarily small. Put another way, the number of distinguishably different frequencies that a photon can have isn't even countably infinite. There exists a very large but finite set of frequencies, such that any photon will always be measured to match a nonempty subset of those frequencies, accurate to the uncertainty of the frequency of the photon. Red Act (talk) 15:43, 8 November 2009 (UTC)

The key point is that they don't need to exactly match your energy gap since nothing is exact in physics. You can work out a degree of precision that is high enough to make absolutely no difference to your experiment (not just negligible difference, but no difference, since the error will be less than the inherent error caused by the laws of physics). That means you can always model the frequencies as rational numbers (by truncating the decimal expression, say). Alternatively, you could model them as irrational numbers of the form pi*q (or any number of other forms) where q is rational, in which case there are still only countably many. So, the physical quantities aren't inherently rational numbers, they are just imprecise enough that we can model them using a countably subset of the reals - we get to choose which subset, within reason. --Tango (talk) 19:11, 8 November 2009 (UTC)

Interactions rarely happen in isolation. In the case of a photon striking a molecule, for example, in addition to electronic excitations, you can also transfer kinetic energy, and excite rotational or vibrational states. The energy in the transition can be fuzzy in part because it doesn't all have to come from or go to the same place. Dragons flight (talk) 20:41, 8 November 2009 (UTC)

pharmaceutical questions

Q 1.what are the application of two and three component system in formulation of liquid dosage form? Q 2.what are the application of HLB in the formulation of W/O and O/W emulsions?

thank you for your help,

your sincerly

getye —Preceding unsigned comment added by Getisha (talk • contribs) 11:54, 8 November 2009 (UTC)

This sounds a bit like a homework question - if that is the case, then as suggested at the top of this page please show where you've gotten stuck after exerting some effort, and we'll try to get you un-stuck. In any case, we do have a very informative article on emulsions, which includes medical/pharmaceutical applications. -- Scray (talk) 15:13, 8 November 2009 (UTC)

aminoacyl-tRNA bond

How in the world is this a "high energy bond"? A sugar alkoxide doesn't look like a very good leaving group to me -- and IIRC the amino acid is not attached via the anomeric carbon. John Riemann Soong (talk) 12:11, 8 November 2009 (UTC)

You should have access to your own reference desk for all these scary questions with words of which I've never heard! DRosenbach ^{(Talk | Contribs)} 15:02, 8 November 2009 (UTC)

I don't know the answer to the question, but Aminoacyl tRNA synthetase and Transfer RNA say the amino acid is attached as an ester linkage on 3'OH terminus of tRNA chain, which is an adenosine ribose ring. Man, our Transfer RNA and Aminoacyl-tRNA articles need help--so full of vague biochemistry descriptors of the actual amino-acyl key! DMacks (talk) 06:38, 9 November 2009 (UTC)

A sugar alkoxide ... I can't see how RO- is a good leaving group simply because it's on a sugar. John Riemann Soong (talk) 10:53, 9 November 2009 (UTC)

As far as a leaving group goes, the enzyme probably protonates it prior to/simultaneously with expulsion (a very common tecnique in enzyme catalysis). So it's not really the alkoxide leaving, but an alcohol. I'm not sure who classified it as a "high energy bond", but it's certainly on par with, if not higher energy than, the final peptide bond, and certainly higher energy than the free amine plus free carboxylic acid. For what it's worth, the Aminoacyl-tRNA article mentions "the net reaction is only energetically favourable because the pyrophosphate is hydrolysed" -- 128.104.112.237 (talk) 00:16, 11 November 2009 (UTC)

Occam's razor + envenomation immunity

How would envenomation immunity be preferentially beneficial for only the vast minutia of the species, such as mongooses and opossums? I'm not attacking evolutionary theory per se...I was just wondering what someone from a non-theistic perspective would say. Pardon me if this is merely another form of an 'inexplainable intermediate form' question.

Ah, yes -- second question -- is this merely another form of the same question that begs to know how inexplainable intermediate forms can lead to otherwise explainable end forms? DRosenbach ^{(Talk | Contribs)} 15:18, 8 November 2009 (UTC)

The key phrase from the article is "feeds on snakes". Only a minority of species feed on snakes. Looie496 (talk) 15:38, 8 November 2009 (UTC)

In case it's not obvious to all readers, Looie496 is referring to the section on immunity among other animals in the Snake venom article. I agree that this is pretty straightforward. One could surmise that some animals got into fights with venomous snakes, and those that had genetic variations that favored survival in such encounters lived to reproduce, and some of those animals gained a food source (venomous snakes). It's clear that frequent and intense selective pressures strongly drive evolution. -- Scray (talk) 15:57, 8 November 2009 (UTC)

So it's because of the overwhelming environmental pressure on snake-eaters to be able to profitably and safely consume their dinners that such mutations would be favored -- whereas non snake-eaters, albeit standing to benefit at large from envenomation immunity, have no such pressure (in the form of removal by of individuals by envenomation death from the population who do not possess such a mutation).

Would it be begging a question to ask why any other organisms don't develop protective entities against their main damage source -- like to ask why all pinnipeds don't possess defensive tusks to defend against shark attacks? Basically, the concept of natural selection allows us to explain the world -- but we do not use it to ask why not? DRosenbach ^{(Talk | Contribs)} 16:04, 8 November 2009 (UTC)

For something to be selected for, it needs:

a) to be present in the population (via mutation, for example)

b) things with it to produce more surviving offspring than those without it, in the form it currently is (not the form that will be arrived at after 100 generations of selection)

Part of (b) is not only that there is an advantage to this thing, but that the advantages outweigh the disadvantages including use of resources. It is perfectly valid to ask 'why not?', but very often the answer is that the cost (in terms of food/energy, time, etc) is greater than the advantage. Organisms do develop protective measures against their main damage source if this reduces the number of surviving offspring, but some forms of defence interfere with others. For example, the Leopard Seal. Leopard seals are very fast swimmers, and they have all sorts of adaptations to allow them to swim faster. They also have sharp teeth, which do not interfere with their ability to swim fast. Let us suppose a leopard seal were born with the beginnings of defensive tusks: larger teeth which did not fit completely inside its closed mouth, but protruded. This leopard seal would be less streamlined than other leopard seals, and thus slower at swimming away from sharks. It would be more likely to be caught by an attacking shark, and those little semi-tusks would be very little good at stopping the shark from eating it. So, this seal with proto-tusks would be less likely to survive to produce offspring, because the proto-tusks would interfere with the existing defence method (swimming very fast). On top of this, there may be other risks associated with proto-tusks: they might be more likely to break than normal teeth, putting the seal at greater risk of infection; they might interfere with normal eating; they take more energy to produce than normal teeth, energy that could be put to other uses.

So, it is fine to ask 'why not?': a lot of progress is made by considering 'why not?'. 86.142.224.71 (talk) 16:45, 8 November 2009 (UTC)

There are two answers here - both have an influence:

• The problem is that things like venom protection requires energy to grow and maintain - in times of famine, animals that have only what they need to survive will out-compete animals that have all of these rarely-useful but energy-consuming adaptations.

• Evolved features don't just stay there when they aren't being actively used. If some species evolves venom protection - but isn't gaining much of a benefit from it, then random mutations that result in that venom protection becoming weaker would not be selected against...the amount of protection would then gradually decrease just from random changes. This reversal of adaptation is actually a surprisingly fast process because mutations that destroy some adaptation are vastly more likely than adaptations that produce benefit. It's like if you took a large hammer and started smashing bits in the engine compartment of your car...what are the odds that a particular random hammer blow will improve the performance of your car? Almost (but not quite) zero. Almost all hammer blows will make the car worse. However, if you never drove your car at night, hammer blows that smashed headlamps or broke the wiring to the headlamps or the switches that turned them on and off would be neither beneficial nor any immediate loss to you. Hence, suppose some species of mouse had venom immunity - it would pretty soon get random mutations in some individuals that would destroy or reduce that ability. In an environment where poisonous snakes were everywhere - the mice without the genes for venom immunity - or with weakened immunity - would be eliminated from the gene pool pretty quickly - so the survivors would all retain that protection - and their offspring would remain venom-protected. But if there are no venomous snakes around, then there is no such corrective mechanism. A mouse with a genetic mutation that wipes our (or reduces) their immunity suffers no disadvantage and can spread it's weakened protection into the next generation. Because destructive mutations so vastly outnumber benefitial ones - any currently useless features can be knocked out without anything preventing the resulting 'defective' animals from reproducing.

For the pinnipeds - you can't just evolve tusks without evolving a stronger skull to absorb the impact - also a more muscular neck perhaps? So this is not necessarily a single, simple adaptation. Perhaps the tougher (larger) skulls prevent efficient live birth out on the ice? Can they still efficiently catch and consume fish with those big tusks out there? Will the lack of streamlining result in them failing to out-swim sharks and then suffering even worse predation? This is a really complex question - and it's by no means obvious that tusks would be an advantage. The answer is very likely that tusks are not a winning option for these animals - or they'd probably have them by now.

SteveBaker (talk) 16:54, 8 November 2009 (UTC)

Being resistant to snake venom is only one way to avoid harm from snakes. Another is to avoid them or kill them. Being resistant isn't a perfect strategy, as you're still getting attacked and bitten by snakes.

It might help to look at how it is that mongooses are resistant to snake venom. Most snake venoms, three-finger alpha-neurotoxins, act on the nicotinic acetylcholine receptors (nAChRs) to block them, which messes with the prey's neurotransmission. Mongooses and other resistant species have an altered binding site in their nAChRs that doesn't allow the toxin to bind but still allows acetylcholine to bind.[28][29]

If a species doesn't regularly get bitten by snakes due to their absence or having other means to combat snakes, there won't be a selection pressure on the nAChRs to develop resistance to snake venom binding. Mongooses eat snakes and hedgehogs rely on hiding and rolling up rather than running away, so will face snake bites. Snakes also have acetylcholine receptors that are resistant to snake venom, as they also get attacked by snakes! Because acetylcholine receptors have things to do other than avoid binding snake venom, like neurotransmission, there is a balance between doing their normal job and becoming resistant to snake venom.

There's also the issue of evolutionary arms races - snakes that don't have their venom work on their prey won't be as successful as snakes whose venom still works, so snake venom will evolve to avoid resistance and still be effective. The selection pressure on snakes to have effective venom will be greater than on most of their prey to be resistant, as every snake needs to feed but not every prey animal in most species needs to be resistant to snake venom, as they rarely get bitten. Fences&Windows 18:52, 8 November 2009 (UTC)

Two questions: swine flu in rodents, and ladybugs in November

Hi. Can the pandemic H1N1 virus infect rodents (esp. squirrels)? Also, how common is it to see a ladybug in November at my location? I'm from Southern Ontario. Thanks. ~AH1^(TCU) 15:44, 8 November 2009 (UTC)

You might want to post such different questions separately. As for the ladybug part, I'd say it's uncommon, but we have had some rather warm weather this November, and I've even seen mosquitos this November, right across the Detroit River from you, here in Michigan. StuRat (talk) 17:44, 8 November 2009 (UTC)

Rodents are used in some lab experiments on influenza, e.g. [30], so many flu strains can infect rodents, but the majority of wild mice are resistant to influenza:[31]. There has been one report of a wild mustelid, a stone marten, being infected with H5N1:[32] It's birds, especially aquatic birds, and pigs that are the main animal reservoirs for influenza:[33]. Rodents and squirrels may carry plague, rabies and Hanta virus among other infections. Fences&Windows 18:20, 8 November 2009 (UTC)

The reason I ask the question about the squirrel is because I recently saw a dead squirrel on the grass, with no signs of trauma or injury (although its jaws were open). Although I had seen a squirrel as roadkill (that wasn't it) and also a different dead squirrel years before, I was curious to what disease, if any, the squirrel may have had that led to its death. My first thought was H1N1, but that would only be possible if they can contract the virus.

About the ladybugs, I've already seen two today, and perhaps one last evening. It has been a very warm day today considering it's November. Do ladybugs usually move somewhere else when it's cold, and does prolonged warmth in late autumn have an effect on its wintertime distribution? ~AH1^(TCU) 19:34, 8 November 2009 (UTC)

So the question is really, "What can a squirrel have died of if there is no obvious external trauma?". Not sure. Poisoning is possible.

Ladybirds/Coccinellidae will find somewhere warm to overwinter, like roof spaces, where they go into diapause. Fences&Windows 23:18, 8 November 2009 (UTC)

I'm in Toronto and I've seen ladybugs in my house a few times in the last couple of weeks, which is unusual. --Anonymous, 05:08, November 9, 2009.

The ladybugs are not the normal ladybugs, but rather Harmonia axyridis, the Asian Lady Beetle. They're slightly larger than our native ladybugs and are considered a pest. Not only do they like over-wintering indoors, the little buggers bite. Squish 'em! Matt Deres (talk) 01:19, 13 November 2009 (UTC)

Proteus Syndrome or Brittle Bone disease

This is just my science fiction idea, not a real medical question. Why not replace the entire skeleton of individuals with these disfiguring bone conditions with titanium? Trevor Loughlin80.0.101.110 (talk) 15:59, 8 November 2009 (UTC)

Ah -- titanium is great, but it is nonresponsive and non-sensory. Bones may appear to be nothing but "framework," but they are dynamic centers of growth and regulation. Not to mention a tremendous (and perhaps the only) store for calcium when the body needs it for things like nerve and muscle electrical conduction and growth. Titanium cannot replace that. DRosenbach ^{(Talk | Contribs)} 16:08, 8 November 2009 (UTC)

Also, the interior of the bones is the place where blood cells are manufactured. Consider the chemical environment that requires - how blood gets into and out of the marrow. SteveBaker (talk) 16:20, 8 November 2009 (UTC)

Who needs blood cells? I'll have a rack of titanium ribs with a tall glass of hemolymph? DRosenbach ^{(Talk | Contribs)} 17:55, 8 November 2009 (UTC)

The article bone has quite a list of uses for bone - protection and structure aren't the only ones. Vimescarrot (talk) 16:54, 8 November 2009 (UTC)

Bones are "alive", not dead, and they play an important role in a number of bodily processes. You can no more just replace your bone with metal than you could your eyes or stomach. --Mr.98 (talk) 18:42, 8 November 2009 (UTC)

I was thinking about it, and returned to post another comment. Titanium replacement parts are not entirely fantasty ala X-Men. I cannot speak of joint replacement (for that is not my field, yet it certainly does occur), but as this idea relates to titanium dental implants, they do not work just like teeth do. Teeth are attached to and supported by the alveolar bone via the periodontal ligament fibers, -- basically modified Sharpey's fibers. These allow for a number of things, including proprioception and cushioning of occlusal (biting) forces, things that are absent with implants, which are osseointegrated, essentially ankylosed to the bone into which it is placed (bone fuses to titanium directly). Ask anyone with enough missing teeth that were restored with implants so that they are able to differentiate the feel of biting on the implants from biting on their natural teeth and they will tell you it doesn't feel the same. That's why dental gurus like Gordon Christensen say 'Implants don't replace teeth -- they replace no teeth." DRosenbach ^{(Talk | Contribs)} 19:12, 8 November 2009 (UTC)

I do think that full-skeleton replacements probably are via X-Men, though. You do need your bones, even if some of the smaller bits can be replaced. --Mr.98 (talk) 00:03, 9 November 2009 (UTC)

I saw a film of a Proteus Syndrome woman with enormous legs, and a Proteus Syndrome small girl with a deformed face, but the rest of their body was unaffected, so there would be room for bone marrow elsewhere. For example, could a complete skull be replaced, bearing in mind that it has only one moving part, the jaw?80.2.205.110 (talk) 10:03, 9 November 2009 (UTC)Trevor Loughlin

Can alpha-carbon protons (in a carbonyl/ketone) hydrogen bond?

Do they undergo deuterium exchange? Do they form hydrogen bonds? How would you explain why dibenzyl ketone has a much lower MP than benzil? John Riemann Soong (talk) 16:50, 8 November 2009 (UTC)

This is just a guess, but maybe benzil's planarity allows much closer packing and so more van der Waals interactions. Dibenzyl ketone has a more awkward 3D shape that probably doesn't allow many VDW forces to form. --Mark PEA (talk) 18:34, 8 November 2009 (UTC)

Furthermore, I would speculate that the full conjugation in benzil allows the pi-systems to participate in intermolecular bonding to a much greater extent than in dibenzyl ketone, where there are two sp³-hybridized carbons which break the conjugation, and do not allow intermolecular pi-molecular-orbital interactions as fully. Come to think of it, this is pretty much the exact same thing as the planar/non-planar difference noted by Mark PEA, but from a different perspective. --Jayron32 04:33, 9 November 2009 (UTC)

Would be interesting to find X-ray crystal structures of the two solids to see exactly how they pack. DMacks (talk) 06:31, 9 November 2009 (UTC)

The crystal structure of benzil has been determined several times, the most recent one I could find was this: Acta Cryst. (1987). B43, 398-405. Benzil is not planar in the solid, the OCCO dihedral angle is about 108°. I couldn't find a structure determination for dibenzyl ketone.

Ben (talk) 16:04, 10 November 2009 (UTC)

Calculated Error query

Okay so I have a slight problem, I'm trying to calculate extension error of a Hounsfield Tensometer calibrated too 0.1mm

So i know to calculate extension I'll use the equation 0.01*100 then i have to devide the answer of that by a value, But i've forgotten what value i should use, Should it be the number of measurements up to the elastic limit or the total number of measurements or what? Help please! —Preceding unsigned comment added by 92.18.81.39 (talk) 21:11, 8 November 2009 (UTC)

You can buy the article Push-pull fatigue modifications to a Hounsfield tensometer which costs $30. Cuddlyable3 (talk) 22:04, 8 November 2009 (UTC)

November 9

Topical decongestant

Template:RD medadvice Nimur (talk) 00:20, 9 November 2009 (UTC)

If you're concerned about an over-the-counter medicine, but don't want to see a doctor, a pharmacist might be able to answer your question. AlmostReadytoFly (talk) 10:56, 9 November 2009 (UTC)

Gay-Lussac's law and Degrees of Freedom in Calculating the Final Temperature of a Gas Undergoing Adiabatic Compression

This question is related to serious confusion I've been having regarding conflicts in method of calculating the final temperature of a gas undergoing compression.

Gay-Lussac's law dictates:

P₁T₂=P₂T₁
so
T₂=(P₂T₁)/P₁

But when doing a similar substitution in the work formula for an adiabatic compression you come out with:

T₂=T₁(P₂/P₁)^(y-1/y)
Where y=degrees of freedom.

This causes significant discrepancies in calculating T₂! Help! I don't understand why there is a difference, and which is correct in which situation. —Preceding unsigned comment added by Gothamxi (talk • contribs) 08:39, 9 November 2009 (UTC)

Your first expression is based on an assumption that the volume doesn't change. Not much of a compression if you do that. More generally, for an ideal gas: ${P_{i}V_{i} \over T_{i}}={P_{f}V_{f} \over T_{f}}$ where the i and f subscripts denote the initial and final states respectively. The adiabatic compression formula is a special case dealing with compression where no net heat is transferred. This is common approximation for a variety of useful situations. Dragons flight (talk) 12:53, 9 November 2009 (UTC)

how do I turn a chloramine back into an amine

Also, are chloramines useful protecting groups for amines? John Riemann Soong (talk) 14:26, 9 November 2009 (UTC)

cyanide...

how fast can cyanide act as a poision???? how can it be detoxified??? who is the inventor of this chemical??? --Lostinscience (talk) 14:35, 9 November 2009 (UTC)rahul

Cyanide was discovered -- nature invented long before we knew of it. Cyanide is dangerous the way carbon monoxide is -- the carbon is nucleophilic and will bind (covalently) to metal coenzymes in your body, deactivating them. Carbon monoxide deactivates heme (an oxygen transport carrier), while I believe cyanide disables parts of the electron transport chain. John Riemann Soong (talk) 14:50, 9 November 2009 (UTC)

You may find our articles on Cyanide#Toxicity and Cyanide poisoning helpful. TenOfAllTrades(talk) 15:22, 9 November 2009 (UTC)

See the articles Gas chamber and Zyklon B (which contains Hydrogen cyanide). Anhydrous ammonia is used to cleanse the chamber after cyanide gas has been used. Cuddlyable3 (talk) 18:43, 9 November 2009 (UTC)

If you can keep the person alive (i.e. with pure oxygen), the best cure is the person's liver - most antidotes are almost as toxic. My old Natural Products lecturer always said that "it only takes seventy milligrams of sodium cyanide to be fatal by complexing all the beta-cytochromes in the body" - I'm sure he must have been planning someone's demise, he was always repeating it (and it didn't come up in the exam either!)  Ronhjones  ^(Talk) 20:02, 9 November 2009 (UTC)

Cyanide antidote kits include injections of sodium nitrate, sodium thiosulfate and amyl nitrate inhalants. [34] 10draftsdeep (talk) 15:23, 10 November 2009 (UTC)

There's something now I have to ask. Agatha Christie (and her ilk)'s murderers invariably use either prussic acid (hydrogen cyanide) or potassium cyanide. Why not sodium cyanide? Does it have properties that make it unattractive for deliberate administration? Tevildo (talk) 21:49, 10 November 2009 (UTC)

The sodium-cyanide bond is stronger than the potassium cyanide bond. Remember, a sodium cation is isoelectronic to neon (but its electrons are more tightly bound). Thus, its electron cloud will be on the same scale as carbon, nitrogen, fluorine, etc. This makes the interaction more covalent -- this in turn makes it harder to dissolve and dissociate sodium cyanide. Protons are smaller, while the potassium cation is bigger. Effectively, this makes sodium cyanide less water soluble and less potent.

An excess of the potassium cation also depolarises cells' membrane potentials. Double killer. (See [[membrane potential].) John Riemann Soong (talk) 01:06, 11 November 2009 (UTC)

Source of Neutron star magnetic field

The Sun has a magnetic field because of convection currents in its conducting plasma. What causes the magnetic field of a neutron star? RJFJR (talk) 17:35, 9 November 2009 (UTC)

It comes from the stellar magnetic field of the progenitor star. As the star collapses into a neutron star, the total magnetic flux through the surface is conserved, so the magnetic field strength increases as the surface area decreases. -- Coneslayer (talk) 19:19, 9 November 2009 (UTC)

But what keeps it going after that? Is it just like a permanent iron bar magnet with magnetic domains locked in alignment? --Tango (talk) 19:30, 9 November 2009 (UTC)

The total magnetic flux through any closed surface is zero... Rckrone (talk) 19:34, 9 November 2009 (UTC)

Sorry, that should be "through any portion of the surface", e.g. the hemisphere containing one of the magnetic poles. The argument for this "freezing" of the magnetic field, along with the slow timescale for magnetic field decay (Tango's question) are addressed in Section 3.1 of Origin and evolution of neutron star magnetic fields. -- Coneslayer (talk) 19:51, 9 November 2009 (UTC)

Ok, so the magnetic fields is generated by free electrons (presumably near the surface since in the middle they will have been merged with protons to make neutrons) flowing around and they flow around because of the magnetic field? That reminds me of electromagnetic radiation - the electric field and magnetic field generate each other so the combination propagates. --Tango (talk) 20:01, 9 November 2009 (UTC)

It seems very similar to the Meissner effect in superconductors: Note that field expulsion (or cancellation) implies infinite conductivity, but that infinite conductivity does not imply field expulsion, because if a material develops only infinite conductivity below its transition temperature, that infinite conductivity will "freeze in" whatever magnetic field was present as the transition temperature was reached. I'm finding articles that predict electron superconductivity in NS crusts, as you say above, but also proton superconductivity in the interior. -- Coneslayer (talk) 14:22, 10 November 2009 (UTC)

Evolution

It apparently violates the establishment clause to either ban the teaching of evolution or require the teaching of flaws in evolution. However, would it be legal for a state to, rather than specifically banning evolution, simply remove evolution from the required state curriculum and not include any questions about evolution on their standardized assessments? ----J4\/4 <talk> 18:02, 9 November 2009 (UTC)

This actually seems more of a humanities question. You might have better luck at WP:RD/H, as your question is about law. Intelligentsium 18:14, 9 November 2009 (UTC)

My understanding is that this would be held to be unconstitutional in the United States, under Edwards v. Aguillard. Your proposal lacks "a clear secular purpose", and I would argue it "undermines the provision of a comprehensive scientific education," which were fundamental requirements in the ruling for such an act to be nonviolative of the Establishment Clause. Comet Tuttle (talk) 18:52, 9 November 2009 (UTC)

Many of what creationists call "Flaws in evolution" are presented to students. They're just not presented in the distorted, blown out of proportion way that you'd get from a anti-evolution tract. They're presented, correctly, as minor details that are still being worked out, points still undergoing debate or research, or as questions that are yet to be answered. It's an important part of good science education to teach that the process is ongoing and that our knowledge is constantly being refined. APL (talk) 19:04, 9 November 2009 (UTC)

AFAIK state legislatures do not write school exams, teachers do. Therefore the state would have to specifically ban teachers from posing evolution questions to make that happen. Cuddlyable3 (talk) 19:43, 9 November 2009 (UTC)

We had this same question not too long ago, I think. It would almost surely fail the Lemon test, as banning evolution would serve no secular purpose. --Mr.98 (talk) 21:23, 9 November 2009 (UTC)

About the best chance you'd have to argue it from a purely secular perspective would be to suggest that the student's time is strictly limited - so it's impossible to teach all of science - so some things have to be left out. The trouble with that is that biologists (correctly) point out that every single thing you learn in biology revolves around evolution. So I think you'd have to somehow justify not teaching biology at all - and that's frankly impossible to justify since we have to (at the very least) prepare children who will go on to join the medical profession. So I don't think that's possible either. IMHO, the Creationists are making a major mistake by even trying to prevent this - you cannot effectively argue against something you don't understand...and producing an entire generation of adults who don't understand evolution makes them easy pickings in a debate with anyone who knows anything about the subject whatever. SteveBaker (talk) 22:33, 10 November 2009 (UTC)

Quotes from an Inventor

I need a quotation from an inventor about his/her work. I don't know very many inventors, and I can't find any quotations from any inventor aabout his/her work anywhere. Does anyone here know any? <(^_^)> Pokegeek42 (talk) 21:21, 9 November 2009 (UTC)

The most classic quotes are probably to be found at Wikiquote:Thomas Edison. --Mr.98 (talk) 21:26, 9 November 2009 (UTC)

Wow. I didn't know there was a Wikiquote. Thanks, that really helps! <(^_^)> Pokegeek42 (talk) 21:34, 9 November 2009 (UTC)

Two from one of my favorite inventors, Dr. Edwin Land

Over the years, I have learned that every significant invention has several characteristics. By definition it must be startling, unexpected, and must come into a world that is not prepared for it. If the world were prepared for it, it would not be much of an invention.

Don't do anything that someone else can do. Don't undertake a project unless it is manifestly important and nearly impossible.

-- LarryMac | Talk 22:22, 9 November 2009 (UTC)

You can't beat the very greatest:

“ Think. ”

Thomas J. Watson, founder of IBM. Nimur (talk) 23:44, 9 November 2009 (UTC)

Was Watson an inventor ? I thought he was basically a salesman. Gandalf61 (talk) 10:32, 10 November 2009 (UTC)

Valid nitpick - but the same can be levied against Thomas Edison, or numerous other "managers of inventors" who get the historical credit anyway. Nimur (talk) 15:48, 10 November 2009 (UTC)

This one isn't from an inventor, but rather an author, George Bernard Shaw. However, it is about inventors:

"The reasonable man adapts himself to the world; the unreasonable one persists in trying to adapt the world to himself. Therefore, all progress depends upon the unreasonable man."

You might also want to view other similar quotes here: [35]. StuRat (talk) 00:33, 10 November 2009 (UTC)

Wikiquote's Category:Inventors is probably your friend. --Tagishsimon (talk) 01:37, 10 November 2009 (UTC)

"The key to success is to risk thinking unconventional thoughts. Convention is the enemy of progress. As long as you've got slightly more perception than the average wrapped loaf, you could invent something" - Trevor Baylis. Gandalf61 (talk) 10:32, 10 November 2009 (UTC)

I am an inventor. You may quote me saying: Patents bring only tears. Cuddlyable3 (talk) 20:26, 10 November 2009 (UTC)

I am an inventor. You may quote me saying: Cuddlyable3 is right - except in the case of patent lawyers. SteveBaker (talk) 02:55, 11 November 2009 (UTC)

Girls to stop growing

At certain age, people will stop growing in heights. Somebody told me males have grown until 25. is this possible for female to grow at 21?--209.129.85.4 (talk) 21:37, 9 November 2009 (UTC)

Certainly possible, though not common. Neither is males growing in height to age 25 common. Googlemeister (talk) 21:50, 9 November 2009 (UTC)

Agreed, it is certainly possible, but rare. It is sometimes caused by hormonal/glandular problems that can have other serious effects, so it might be worth talking to a doctor, especially if the person is already unusually tall. --Tango (talk) 22:03, 9 November 2009 (UTC)

human growth, Human development (biology), human height - none of them seem to address this. Did I miss a more relevant article? 75.41.110.200 (talk) 22:11, 9 November 2009 (UTC)

We don't seem to have a relevant article, but if you look at, for example, Robert Wadlow (the tallest man in recorded history), you'll see his height was caused by hypertrophy of the pituitary gland, which caused him to keep growing for his whole life (he died at 22, though). Extreme heights like this can put additional strain on the heart, skeletal system, etc.. --Tango (talk) 22:50, 9 November 2009 (UTC)

WHAAOE. Gigantism and Acromegaly both apply to pituitary growth hormone excess. Not that it has really anything to do with the OP's question, of course. As far as I can tell the question is about normal growth and development. The growth of the long bones is limited by the closure of the growth plates, which occurs toward the end of puberty -- see the section on "differences between male and female puberty" for a discussion of why females usually stop their growth spurt at a younger age than males. With that being said, there's no reason why a girl with delayed onset of puberty might not continue growing longer than her peers, thereby ending up taller. --- Medical geneticist (talk) 00:29, 10 November 2009 (UTC)

It depends on your definitions, but a women still growing at age 21 isn't particularly normal. It could just be an extreme of normal development (long tails and all that) or it could be decidedly abnormal. I would rather let a doctor decide which it is than random people on the internet. --Tango (talk) 04:55, 10 November 2009 (UTC)

Simple. Modify the biological clock machinery that give rise to these events. I don't know how much we know about the molecular machinery that dictates the onset of machinery and what cues are taken, etc. but it's quite simple to envision an analogue to the per-tim-dbt-clk/cyc sort of circuit you see for the Circadian clock. Mutations in these proteins can trigger abnormally long/short periods so if there's an oscillator regulating growth similar variants in those proteins might be responsible for the distribution of ages seen for a particular stage of development. John Riemann Soong (talk) 22:35, 9 November 2009 (UTC)

Such developmental patterns are wildly variable in both genders. For two data points: I reached my full adult height at about age 13. At 5 foot 9 inches in the 8th grade, I was among the tallest in my class. I'm still 5 foot 9 inches tall today, some 20 years later. Noted basketball player David Robinson did not reach his full 7 foot 1 inch height until the age of 21, his senior year at the United States Naval Academy. While the two of us probably represent statistical outliers, there are still some rather larger error bars on the "average age when full adult height is reached" data set. --Jayron32 03:25, 10 November 2009 (UTC)

More anecdotal evidence - my wife had reached her full (normal) adult height by age 13. (She's now well over age 25, so not likely to grow any taller.) Mitch Ames (talk) 03:33, 10 November 2009 (UTC)

A man not growing past 13 sounds very unusual, as is being 5'9" at age 13 (it's off the scale on the two online percentile charts/calculators I've checked, so at least top 3% but I think it is more like top 0.1%, the calculators just aren't calibrated at such extremes). A man growing until 21 isn't particularly unusual, though. A women reaching her final height by 13 isn't so unusual. --Tango (talk) 04:52, 10 November 2009 (UTC)

No joke. In the summer after my 8th grade year, I was easily a full head taller than nearly all of my classmates. By the time I graduated high school, many of my male classmates had passed me by. I may have been a tad smaller than 5'9" at the time, i.e. I may have stopped growing in my 14th year rather than during my 13th, but I pretty much remained exactly the same height for ALL 4 years of high school. --Jayron32 06:19, 10 November 2009 (UTC)

Well, if my estimate (ok, guess) is right and it puts you in the top 0.1% then there are about 2 million men than would have been that tall by that age in the world. It's unusual, sure, but there are a lot of people in the world so unusual things do happen. I guess it isn't surprising that you would stop growing early if you were already that tall - there is far more variation in rate of growth than there is in final height. If you don't mind me asking, did you reach other puberty milestones earlier than your peers as well? --Tango (talk) 17:47, 10 November 2009 (UTC)

magnetics question

Is the magnetic strength of magnets additive if I stack 4 magnets one on top of the other, can I lift something 4x as heavy as a single magnet could? I would suspect not, but then how much heavier? If it helps, you can assume cube shaped magnets. Googlemeister (talk) 22:18, 9 November 2009 (UTC)

Correctly computing the force between ferromagnets and a metal surface (like paper-clips) is extremely complicated, and requires both a very nontrivial vector calculus treatment as well as some pretty intense empirical correction factors. You can see some of the simplest approximations that are experimentally useful at Permanent magnet#Calculating the magnetic force. Nimur (talk) 23:49, 9 November 2009 (UTC)

For one thing, if you stack the magnets, then all but one of the magnets will now be further away from the object you're trying to move, and this will decrease the load they can carry. If you place them side by side, on the other hand, then I suspect that you would come close to having 4 times the lifting capacity of a single magnet. StuRat (talk) 00:23, 10 November 2009 (UTC)

If you place them side-by-side, with their poles aligned so they all attract the paperclips, the magnets will repel each other. As I mentioned above, the correct treatment requires calculating the effective lines of flux, calculating the induced magnetism in the object that will be attracted; and integrating. Each stage of this treatment requires thorough, 3D solution of Maxwell's equations, accounting for material properties and assuming precise knowledge of the magnetic field inside the ferromagnets. Nimur (talk) 00:54, 10 November 2009 (UTC)

Some side by side arrangements are better than others.—eric 01:50, 10 November 2009 (UTC)

So I take it then that treating magnets which are stacked to be akin to batteries wired in series would be incorrect? Googlemeister (talk) 14:58, 10 November 2009 (UTC)

That would result in an extraordinarily inaccurate approximation. The level of accuracy of course depends on the particular geometry, the particular magnetic fluxes of each magnet, etc. I am sure that there is some set of approximations and limiting cases where you could arrange some sort of analogy, but keep in mind that magnetic field strength is much more dependent on spatial geometry than electric current that is constrained to remain in a wire. Nimur (talk) 15:51, 10 November 2009 (UTC)

Could the approximation be improved by modelling the air as a resistive electrolyte? Cuddlyable3 (talk) 20:24, 10 November 2009 (UTC)

sterics of proteins and interactions between R groups

Is it me or do protein chains look really ... cramped. Is there a polymer stereochemistry for the polyamide bond (e.g. does -NH2 prefer to add below the carbonyl or above?), and besides cysteine disulfide bonds, it seems to me that ring condensation and the like could potentially occur, say between NH2 and COOH R groups, if it was so desired that their amide formation be catalysed? John Riemann Soong (talk) 22:31, 9 November 2009 (UTC)

Cysteine dithiol linkages aren't the only inter-amino-acid linkages that occur in proteins, there are lots of other sorts of interactions. There are "hydrophobic interactions", such as between alkenyl side chains (valine, leucine, isoleucine), as well as hydrogen bonding interactions, lewis acid-base interactions, etc. etc. There are a full variety of inter-amino-acid interactions. Pretty much any sort of bonding or interaction or reaction one may find in chemistry can occur in a protein. Such complex interactions are what give a protein its secondary, tertiary and quaternary structure. Sadly, our article on tertiary structure is quite lacking, but a decent biochemistry or molecular biology textbook should have a decent section on the chemistry behind this sort of dense protein folding. --Jayron32 03:58, 10 November 2009 (UTC)

Yes but these appear to be quite "long-range" and based on folding. I was really referring just more of "steric collisions" and covalent ring condensations. (Most of the other interactions are non-covalent...) John Riemann Soong (talk) 12:44, 10 November 2009 (UTC)

What arthropod is this?

I think these are scale insects but I'm not certain. As far as I can tell Wikimedia Commons does not have another image of this species. Can anyone help me narrow down what these little guys are? -Craig Pemberton (talk) 23:42, 9 November 2009 (UTC)

For questions like these people usually want to know where geographically the photo was taken, and on what sort of plant the critters are on. --Sean 01:24, 10 November 2009 (UTC)

Such people could click on the image to learn "stalk of grass in Flagstaff, Arizona". --Tagishsimon (talk) 01:31, 10 November 2009 (UTC)

Aphids? The look to be the right size. There are 10 families and hundreds of genera and species of aphids, but based on the behavior and location (clustered around the stalk of a plant) I would fathom a guess that these are aphids of some sort. --Jayron32 02:32, 10 November 2009 (UTC)

Hey I think you're right! =D I never would have guessed but it makes perfect sense. That gets me to Insecta Hemiptera Sternorrhyncha Aphidoidea. I doubt they belong to Anoeciidae because they were not on the roots and I doubt the belong to Pemphigidae because I've never seen a gall on a "monocot". The remaining blue-linked taxon is Aphididae which apparently contains the majority of the species and is a great place for me to start. Thanks Tagishsimon for standing up for me, Jayron for the good eye. -Craig Pemberton (talk) 03:07, 10 November 2009 (UTC)

On a possibly related note, I also ran into this guy which looks a lot like these aphids but is lacking cornicles. Any ideas? -Craig Pemberton (talk) 10:28, 10 November 2009 (UTC)

Some type of tree cricket, perhaps the Snowy Tree Cricket [36]? Mikenorton (talk) 11:09, 10 November 2009 (UTC)

November 10

Urinary tract infections messing with the mind

I've known multiple elderly individuals who, when experiencing urinary tract infections, became quite confused and temporarily appeared to have dementia while fighting the infection. Their doctors don't generally seem to be surprised or alarmed by the mental issues, so I assume that this is a common symptom of such an infection. Why does this happen? I can't quite see why an infection of the lower body would so mess with the mind. Nyttend (talk) 03:41, 10 November 2009 (UTC)

Without wanting to delve into medical advice, infections lead to fever and high fevers can lead to temporary impared cognitive ability such as delirium; such problems are likely magnified in the elderly. Many people have had a bad flu at sometime in their lives, and can attest to some level of cognitive imparement during especially bad fevers. I suspect, though could not say for certain, that this is what is going on. --Jayron32 03:51, 10 November 2009 (UTC)

I can also see the reverse happening, that dementia might cause urinary infections, especially in females, due to poor hygiene. StuRat (talk) 04:30, 10 November 2009 (UTC)

Just to pile on the WP:OR, I've observed itcorrelation of UTI and temporary symptoms of dementia/delirium' in both males and females. DMacks (talk) 04:54, 10 November 2009 (UTC)

Fever induced delirium or dementia induced urinary tract infections? If the latter, how do you know the cause? --Tango (talk) 04:56, 10 November 2009 (UTC)

Sorry for vague antecedent. Fixed. DMacks (talk) 05:09, 10 November 2009 (UTC)

Acute worsening of mental status (a change from mild dementia to frank delirium) is frequently associated with infections of all kinds. UTIs seem to be a particularly frequent cause in the elderly (possibly for reasons stated above). From delirium:

"...there is an interaction between acute and chronic symptoms of brain dysfunction; delirious states are more easily produced in people already suffering with underlying chronic brain dysfunction. A very common cause of delirium in elderly people is a urinary tract infection, which is easily treatable with antibiotics, reversing the delirium."

The typical pattern seems to be: dementia --> UTI --> fever --> delirium --> antibiotics --> resolution. However, you don't necessarily need dementia for the pattern to start. --- Medical geneticist (talk) 13:37, 10 November 2009 (UTC)

The obvious way to break the link of dementia causing UTIs is proper care. If the patient defecates in their pants, it should be immediately detected and cleaned up, using a disinfectant, so there's no opportunity for the UTI to develop. StuRat (talk) 13:52, 10 November 2009 (UTC)

I think the doctor would have minimal concerns about the person's mental state because he knows (as do most experienced care staff) that once the infection is dealt with the chances are very high that the person's mind-state will return to normal. Just because the seat of the infection is in the urinary tract does not mean that the associated toxaemia will not spread through the body and affect other parts - like, for instance an already partly disabled brain. If the person has a temperature this will further compromise the oxygenataion of the struggling brain with consequent mental confusion.

Cleaning the soiled area after faecal incontinence is a help, but many urinary infections are caused by lack of proper hydration and infrequent voiding of the concentrated urine. Dehydration is a major problem in people with dementia (and other mentally incapacitating conditions) in hospitals or nursing homes. It is not unknown for care staff to be less free than necessary with liquids to avoid the urinary consequences. Caesar's Daddy (talk) 14:54, 10 November 2009 (UTC)

OR I've had elderly relatives admitted to hospital with dementia, and the UTI was not diagnosed until after discussion with the carers. The conversation would go somethign like this: "Your mother/ mother-in-law's been admitted to hospital. Can you tell me if she's confused normally?" When I said she wasn't, then she'd immediately be started on antibiotics and her urine tested for an infection. This has happened to me about 3 times, and I still can't understand why confused elderly people aren't routinely tested for UTI's as a direct cause of confusion. On all 3 occasions, the patient had had no problem with incontinence, either urinary or faecal, nor had she had problems with dehydration, as she had up until that time been caring for herself at home. There must be some research on this as the first instance I'm talking about happened about 15 years ago: however, I'm no longer able to access the relevant medical libraries to confirm this.--TammyMoet (talk) 16:23, 10 November 2009 (UTC)

Port transportation and inventory cost with lead time consideration

Can Wikipedia help in finding journal papers relevant to Port and Modal Elasticity study by Robert C Leachman? The link for this paper is: http://www.metrans.org/nuf/documents/Leachman.pdf

Since I am new to finding relevant journal papers, I have difficulty relating papers. Few example papers and other suggestions for relating and searching relevant journal papers will be appreciated. —Preceding unsigned comment added by 113.10.121.178 (talk) 06:24, 10 November 2009 (UTC)

There are others, but Google Scholar springs to mind as a search engine which focuses on academic journals. --Jayron32 06:34, 10 November 2009 (UTC)

For example, typing "Port and Modale Elasticity" into Google Scholar returned this search. I have no idea how helpful this one search is, but you may be able to play around with the search terms and find what you are looking for. --Jayron32 06:36, 10 November 2009 (UTC)

Blood Donation and Alcohol Consumption

I need an urgent advice. Somebody asked me to donate blood. Even as they asked I was sipping a sixty ml of White Rum. Nothing more than that. Not a drop yesterday. In other words only sixty ml in 48 hours. Will the docs rule me out? What complications can occur if I hide the fact? Urgent information sought. --117.204.82.26 (talk) 07:11, 10 November 2009 (UTC)

We definitely can't provide medical advice here (especially since it could potentially affect your health as well as X unknown others who receive your donation). But also, the exact qualifications vary from place to place. Best to call the donor center and ask...you can usually do that anonymously. I won't get on my soapbox and tell you what I think about doing something that you suspect may put someone else at risk. DMacks (talk) 07:32, 10 November 2009 (UTC)

You will find lots of information here, including a long list of restrictions on who can give blood. Interestingly, alcohol doesn't seem to be mentioned, so presumably it is not a big deal for them.--Shantavira|^{feed me} 09:39, 10 November 2009 (UTC)

That would be because only a small portion of the donated blood will end up in any individual patient, meaning that the alcohol will be well diluted. Still, if you were dangerously drunk, I'd expect that the amount of alcohol the patient receives might be enough to feel some minor intoxication effects. If you were so obviously drunk, then they might refuse the donation just because of the risk of you injuring yourself or others during the donation process. StuRat (talk) 13:46, 10 November 2009 (UTC)

I have donated blood a number of times, and they asked me extensive questions each time. Whether or not I had consumed alcohol was never an issue. To be on the safe side, when you go to donate blood, explicitly say that you just drank X amount Y time ago, and ask if you can still donate blood. — QuantumEleven 13:48, 10 November 2009 (UTC)

Donated blood is not blindly dispensed to patients straight from storage after receiving from the donor. Extensive testing is done to determine quality, type and safety: [37] 10draftsdeep (talk) 15:38, 10 November 2009 (UTC)

I've also donated blood several times (in the UK) and I don't remember alcohol being mentioned at all. Pretty much everything else you can think of, but not alcohol. --Tango (talk) 16:31, 10 November 2009 (UTC)

From what I've heard of binge drinking in the UK, they might be concerned that blood with too low of an alcohol content would be a shock to the system of the recipient. :-) StuRat (talk) 17:47, 10 November 2009 (UTC)

According to the Guide to the preparation, use and quality assurance of blood components, 14th edition 2008, Europeean Directorate of Medicines & Health Care:

"Persons clearly under the influence of alcohol should be deferred until sober." (page 61).

The main concerns with people not being sober when donating are (1) increased risk of the donor not being able to reply accurately to the questions asked about risk factors etc., and (2) the possibility of increased risk of injury to the donor after donation. --NorwegianBlue ^talk 21:15, 10 November 2009 (UTC)

Help identifying a bird

File:Ys cover.jpg What kind of bird is depicted in the cover of Joanna Newsom's Ys? Thanks! 189.15.180.169 (talk) 07:34, 10 November 2009 (UTC)

It looks like it could be a chough. It is the only corvid I know with a beak and legs of a yellow/orange colour. Caesar's Daddy (talk) 07:53, 10 November 2009 (UTC)

Knowing Newsom, there is probably quite a lot of symbolism or possibly wordplay going on here. Sickle, sphinx moth?, Ipomoea, a cherry, the strange perspective which almost seems like it could be an allusion to a work or artistic school (early experiments with perspective?). Maybe the humanities or entertainment reference desks could get you further on these fronts? It's possible that the bird isn't modeled after any species in particular but then again she does pay close attention to her specimens. -Craig Pemberton (talk) 11:00, 10 November 2009 (UTC)

Or maybe she just likes the way chough is pronounced. It is an odd one. Assuming it is a corvid that gets you down to 120 species, quite simple. Caesar's Daddy, how do you tell if it is a corvid? -Craig Pemberton (talk) 08:21, 11 November 2009 (UTC)

Experience mostly. Reading books, looking at birds, watching wildlife films. Most, but not all corvids are dark or black. This particular bird is easily recognisable by its beak and legs and resident in the UK, among other places. It's a bit like recognising a parrot, when you've seen a few species you can recognise what your looking at. Most importantly it is not a perfect system. Caesar's Daddy (talk) 08:39, 11 November 2009 (UTC)

Energy stores after exercise

I've looked at many of the relevant articles and I'm sure the answers are there but they get quite technical. After aerobic exercise, glycogen levels are lower than normal. How are they replenished if one doesn't eat afterwards? I believe the energy can come from fat stores or proteins - but is there a mechanism that would perhaps favour one over the other? Thanks, Zain Ebrahim (talk) 11:21, 10 November 2009 (UTC)

I believe that energy is normally restored from fat, with protein only being used when this method fails (such as in a person with no fat reserves remaining). StuRat (talk) 13:33, 10 November 2009 (UTC)

(Biology) Attraction to super-natural features?

I've spent a while searching for this topic, but I guess I'm using the wrong terms, or framing it badly or something. What's the word for the (sexual?) attraction to features that are exaggerated beyond their natural limits? The classic example I always heard is that human males are more attracted to freakishly red lips (colored with lipstick) than to naturally red lips. I vaguely remember reading about animal studies where they reacted more strongly to an artificial, exaggerated stimulus that the researchers came up with, than to the natural stimulus. Maybe it was rats with artificial sweeteners? I'm not sure. Any idea what I'm talking about? Indeterminate (talk) 11:44, 10 November 2009 (UTC)

This "more is better" attraction also seems common in our diets, where we crave more sugar, salt, and fat than our bodies can actually handle. In this case, the reason is that those items were scarce when we evolved, so the problem of excess quantities was so rare we didn't need a way to deal with it. Similarly, if women with excessively red lips were showing a sign of some common disease, then we might have developed an aversion to them, but this isn't a common problem, so we didn't. A lack of red lip color, on the other hand, could show several health problems, such as anemia, which would make such a woman a poor choice for a mate. So, to be safe, the woman with the reddest lips is chosen. StuRat (talk) 13:40, 10 November 2009 (UTC)

I think the main reason men have evolved to be attracted by lip appearance is because it's an indicator of fertility. Redness, thickness and eversion of lips peaks in a woman's mid-twenties, when she is most fertile.[38] Red Act (talk) 18:12, 10 November 2009 (UTC)

Boob jobs in humans might be a similar phenomenon. Edison (talk) 14:41, 10 November 2009 (UTC)

Supernormal Stimuli--Digrpat (talk) 15:21, 10 November 2009 (UTC)

Yes, that's the term, and in this case, that which is subject to sexual selection. Imagine Reason (talk) 17:20, 10 November 2009 (UTC)

Dissociation

Hi,

The way I understand it, if one dissolves salts in water, then ions dissociate, resulting in a soup of ions. Say, I dissolve some NaCl and $CaCl_{2}$ in water, there appear

$Ca^{2+},CaCl^{+},Na^{+},Cl^{-},H^{+},OH^{-},CaOH^{+}$,

right? Is there a study showing relative concentrations of the ions at the equilibrium of reactions like the following?

$Ca^{2+}+OH^{-}\rightleftharpoons CaOH^{+}$

I am most interested in concentration of ions of valency 2 or higher, like $[Ca^{2+}]$ or $[SO_{3}^{2-}]$. Is it reasonable to assume that concentrations of these ions are negligible comparing to the ions of valency 1? (Igny (talk) 14:09, 10 November 2009 (UTC))

Not necessarily. Metal ions of charge 2+ or higher are often quite adept at binding hydroxide, thereby lowering the pH of an aqueous solution. Someone with a good textbook in inorganic chemistry close at hand can probably put some numbers to that. TenOfAllTrades(talk) 15:43, 10 November 2009 (UTC)

Just to make this clear. Concentration $[Ca^{2+}]$ is negligible compared to $[CaOH^{+}]$ and $[CaCl^{+}]$? (Igny (talk) 15:12, 11 November 2009 (UTC))

Mis-information about the "Great Pyramid"

Below is a copy of a letter sent to the History Chanel with specific reference to the Great Pyramid.

I am an engineer that has done research on work within the "Great Pyramid" as part of a National Geographic team. It is high time that someone check the facts on some of the conjecture that is being presented as fact on your programs. For starters, this particular program keeps referring to the "Great Pyramid" the actual pyramid that is depicted and as the center of focus is actually the Pyramid of Khafre It is a MISTAKE, a common one but still it is highly inaccurate. I can also tell you straight out that as an MIT educated engineer that all the claims about everything being in "perfect" alignment and the "perfect" alignment with this or that is a lot of horse hockey. There isn't enough of the pyramid in tact to tell for sure where it is aligned and it is painfully obvious to the trained eye that there are many parts of the stone work that are far from "perfect". It is high time that all this crap cease to be presented as fact by people that I can only guess are as full of horse hockey as the statements they are making. If you are going to present something as "fact" then somebody needs to check what the facts really are. If there is this much mis-information about the Great Pyramid in this program then the rest of the program is highly suspect. I love Si-Fi but you are suppose to be the "History" channel.

67.142.161.35 (talk) 14:47, 10 November 2009 (UTC)

OK. --Sean 14:53, 10 November 2009 (UTC)

Is there a question involved? Googlemeister (talk) 14:56, 10 November 2009 (UTC)

I guess linking to The Great Pyramid, Pyramid won't help? Also it's probably not worth noting that The History Channel and Wikipedia are not (at least to my knowledge) part of the same organisation so problems about the accuracy of one isn't going to be resolved by informing the other. Or do you want to know if the comments in the letter are correct? 194.221.133.226 (talk) 15:55, 10 November 2009 (UTC)

I'm trying to assume good faith on your part, but you may want to exercise caution with regard to misrepresenting your credentials. MIT has an extremely high standard for its students' English and writing skills; you are doing no justice to your institution when you write malformed and angry letters to the general public that are replete with spelling errors and poor grammar. If it turns out that you are not actually from MIT, they will likely track you down - they have had a lot of recent bad publicity with respect to misrepresented credentials. Nimur (talk) 16:00, 10 November 2009 (UTC)

No misrepresentation at all. Graduated BSME class of 94. And your credentials are??? I don't know how many engineers you have ever dealt with but most of them have language proficiency far below mine. MIT tracking me down? Only if they want a contribution to the alumni fund.

Just basically wanting to vent. I spent about 10 days working inside the "Queen's Chamber" and do have first hand experience. In truth, I did not walk the entire perimeter of the pyramid but I can say for certain that on at least 3 sides that I did look at that there is not enough of the original stone work in tack without considerable damage and erosion to tell for sure where it is pointed. As far as interior stone goes, other than the stone work inside the king's and queens chambers, there is very little of it that can be considered "high precision".

Just one point that is of particular interest are the claims that the shaft exiting the south side of the Queen's Chamber is at a very specific angle and points to such and such. The shaft in fact takes a left hook part way up (about 10° at a guess) that is very obvious from video that we took on the project I was involved with. This information has never been published or released to my knowledge.

My point is just not to believe everything that is published as "fact". —Preceding unsigned comment added by 67.142.161.29 (talk) 20:48, 10 November 2009 (UTC)

The OP only says they are MIT educated, not an MIT graduate, so they haven't,strictly speaking, claimed any real credentials. --Tango (talk) 16:37, 10 November 2009 (UTC)

Sorry for my initial response. Nimur (talk) 15:41, 11 November 2009 (UTC)

As for your actual claims, while much of the surface stone has been removed from the pyramids, they are still substantially intact, unlike the earlier mud brick pyramids that are now in total ruins. So, by measuring the alignment of the interior blocks, one could determine what, if anything, they are aligned with. The claim I'm familiar with is that they aren't aligned with the north star of today, but rather with it's position when they were built. I do tend to agree with you that The History Channel, The Discovery Channel, The Biography Channel, and even PBS, often do a poor job of reporting facts, being more interested in entertainment (and the funds this brings in, either through advertising or pledges) than education. Still, you have to grade them on a curve, meaning that anything is better than the crap on the rest of the TV stations. StuRat (talk) 17:11, 10 November 2009 (UTC)

I share the OP's love of Sci-Fi. About a year ago I received the following in an e-mail from another pyramid enthusiast.

The contents of Cheops include ( there is some evidence, and some legends,) the Ark of the Covenant, the Emerald Tablets of Hermes, the 42 Books of Toth, the archives of the predecessor civilization, and three entombments. The keys to consciousness lie within. Which is also to say the keys to immortality. Not an immortality that simply means one never dies, but an immortality that eliminates the need for biological birth to come and go in the matter world, and this Earth plane, at will.

The entrance to Cheops and the entrance to the Hall of Records have a common vestibule.

Humans are naturally immortal. The teachings of the Mystery School at Giza were how to control it. Belief had nothing to do with it.

I have kept this closely held. I am taking a chance in telling it to you. Please just file it in your head and watch and see what happens. Nobody in the west takes me seriously, but the Egyptians know me as a dangerous revolutionary. I am watched and guarded when I go there. Cuddlyable3 (talk) 20:16, 10 November 2009 (UTC)

Response to the OP: The History Channel exists to make you watch commercial advertisements. They do this by creating little bits of entertainment which are interesting enough to keep you watching and not changing the channel to find some other show to watch. Now, here's the important bit. The deal is, "stuff that the majority of authorities believe to be true" tends to be stuff we already learned in school, so that stuff is unlikely to hold a viewer's attention. There was a time when the History Channel ran shows which spent time teaching people about the accepted view on historical events; i.e. exactly the same stuff you could learn from most history books and the like. It turns out that, since people are already fairly familiar with this viewpoint, they don't watch the shows as much as when you run a show whose theme is EVERYTHING YOU KNOW ABOUT THE WORLD IS WRONG!. When people see that as the theme of the show, they get much more interested in watching the commercials in between the segments of the show. Being that the History Channel is intersted in staying in business, they have shifted from showing shows which tell you stuff everyone believes to be true to showing stuff that only a few insane nutjobs believe to be true because the latter tends to cause more people to watch commercials. Such is the way it works. --Jayron32 03:53, 11 November 2009 (UTC)

I've even seen some of this on PBS. For example, they had one nut-job on there giving his theory of how ancient Central and South American stonework was done by carving the stones with light. They did thoroughly debunk this by having reputable scientists tell us how ridiculous that would have been (by requiring a precision-ground mirror the size of a football stadium, which we couldn't even build today), but they still felt the need to give this nut a forum to present his wacky theory. And when pledge week comes around they bring out their own nuts, like Wayne Dyer and Gary Null, who seems to think that it's unhealthy to have poop in you colon. StuRat (talk) 14:52, 11 November 2009 (UTC)

Around these parts, we just get a WIKIPEDIA FOREVER banner and the usual Reference Desk population-at-large... Nimur (talk) 15:38, 11 November 2009 (UTC)

For over two centuries, deluded nutjobs have made sensational claims about "precise alignment" and "exact dimensions" of the pyramids, such as the claim that its sides were integral multiples of the Pyramid inch, with precision of 8 decimals. But the face stone or finish stone was long ago removed for other monuments, and the crude underlying stone has eroded. Where should a surveyor place the instrument to check the "precise alignment" or measure the "exact dimensions?" The "precise" results depend on arbitrary placement, which later researchers decided was off by a couple of feet. Edison (talk) 15:37, 11 November 2009 (UTC)

Organ donation system in the US

Is it even remotely feasible (outside of movie plots) for a person in the US to be identified as donor-compatible by some genetic characteristics (blood type, DNA fingerprint, Genome sequence, etc.) and as a result be killed so that their organs might come to bear on the transplantation exchange, and end up being given to a designated beneficiary? Following the logic, it would require that the beneficiary of the perpetration be already at the 'top of the list' of compatible recipients to even have a shot at receiving the organ, so a follow up question would be, are these lists very closely guarded as a matter of policy? The final question would be (probably something for the humanities desk), how large of a pool of murder victims could go undetected by investigators (presuming that the beneficiary is not at the top of the list, and multiple compatible people must be killed to increase the probability of success) so as to not reveal the ultimate motive?

I pledge that I am not researching this for any ulterior motive than to explore the possibilities (for a factually correct work of fiction, perhaps.) I would gladly accept any articles related to this topic, in lieu of specific answers. Thanks! --Jmeden2000 (talk) 17:13, 10 November 2009 (UTC)

One flaw in that concept is that the murder victim's organs would mostly be unusable if the body is just left out until somebody happens to find it. Usually organs must be removed shortly after death to be viable, which typically only happens if the person dies in a hospital, although some organs last longer than others. And if piles of murder victims start showing up at the entrance to the organ transplant unit with their donor cards taped to their foreheads, somebody might catch on. :-) StuRat (talk) 17:38, 10 November 2009 (UTC)

Well in one book I read, the murderer stuck the dead guy in the fridge and tipped off the cops so it was found quickly. That sounds like an option. Googlemeister (talk) 17:40, 10 November 2009 (UTC)

In the UK, deaths from murder are "unnatural" and reported to the coroner. With murder, the coroner will invariably perform an autopsy. Thus the organs would be unusable for donation. With road traffic accidents, if the death occurs in hospital (usually the intensive care unit), the organs may be salvaged for donation, as long as the cause of death is clear. Axl ¤ [Talk] 18:07, 10 November 2009 (UTC)

Here is a comment about the situation in NSW Australia. Axl ¤ [Talk] 18:16, 10 November 2009 (UTC)

(Edit Conflict)There are persistent rumours that, in various parts of the world, "involuntary donors" are identified, abducted, murdered and the required organ(s) harvested on commission from rich and unscrupulous transplant requirees. Only a couple or so criminal/suborned individuals within the medical establishment carrying out the transplant (probably including one of the surgeons and someone involved in the donation documentation process) would be sufficient to bring this off. Since, like the rest of the world, the US has its share of unscrupulous or subornable individuals the scenario must be at least possible. Such a conspiracy would easily be able to dispose of the victim's remains without detection. Since so many people go missing annually, and since there need be absolutely no connection between victim and perpetrators, a low level of such activity might well go undetected for at least a while - my own opinion, FWIW, is that it probably does. The concept has been treated fictionally by the Science Fiction writer Larry Niven (who coined the term "organlegging" to describe it), medical techno-thriller writer Robin Cook (I believe), and doubtless others. 87.81.230.195 (talk) 18:25, 10 November 2009 (UTC)

Seems like a variation on blood libel or penis panic. --Sean 19:35, 10 November 2009 (UTC)

"Since so many people go missing annually" --Is there a basis for this claim? Unsolved (but confirmed) murders do not count in this case, as we have worked out that the likelihood of organ donation from such an incident is nearly 0. --Jmeden2000 (talk) 19:40, 10 November 2009 (UTC)

According to the Missing person article, there were about 109,000 active missing-person cases in the US at the end of 2005. I'm not sure how many new cases annually that would translate to (the article may give relevent reference sources), but clearly it's enough in which, say, a dozen annual cases of murders-for-organs could lurk. Understand, I'm not asserting that they actually happen, but addressing the OP's question as to whether it's feasible. 87.81.230.195 (talk) 12:32, 11 November 2009 (UTC)

That very same article goes on to say that the list *shrunk* by 10,000 names in 2005, so we apparently found more than we lost... the time sensitive nature of a missing person case no doubt makes it very hard to track, so those numbers aren't really any good for this purpose. I need to know the statistical rate at which a name is added to the list, never to be removed. --Jmeden2000 (talk) 14:21, 11 November 2009 (UTC)

Our article on Autopsies seems to suggest that it is generally required when the cause of death is suspicious or subject to debate, not necessarily any situation that is "unnatural". Are there any references to US or UK law (or other nations) that clarify this? Is it presumed that the time the body would sit waiting for the yes/no verdict by the coroner would ruin the organs? --Jmeden2000 (talk) 19:30, 10 November 2009 (UTC)

Jmeden2000, you are correct. In the UK, all unnatural deaths must be reported to the coroner. If the cause of death is obvious and there is no suggestion of foul play, the coroner may choose not to conduct an autopsy. However in cases of murder, the coroner will invariably conduct an autopsy. Axl ¤ [Talk] 19:37, 10 November 2009 (UTC)

Looks like there are three possible scenarios: 1.) Causing a natural-looking death (e.g., a car accident) when you're at the top of the list; 2.) Murdering someone and making sure that the corpse is found soon (or better even: dies at a hospital) and the needed organs are not needed by the coroner... probably riskier than [1]; and 3.) Murdering someone and letting the corpse disappear... although it seems to require a lot of taste for conspiracies to like a book about this third scenario. :) - As for the lists, to my knowledge candidates for transplants are well-informed about their position on the list (and the time it usually takes before they may get a transplant). After all, it's often pretty vital information to them... Finally, the number of murder victims obviously depends on your choice of scenario. It also depends on your location--murders in close proximity will clearly be suspicious much faster; and when you mention the US, you may even deal with different jurisdictions (different states), which should further obstruct fast detection. I'm sure by the time they catch on, you'll have left the hospital with your new liver in place. ;) --Thanks for answering (talk) 02:36, 11 November 2009 (UTC)

Surely it would be easier to murder the people in front of you on the list? Obviously you'd still need to get away with that, but presumably these are pretty ill people: who'd look to closely if a few of them seemed to die of complications of their disease? And a couple could have accidents, not too close together obviously. Oo, you could have some sort of 'organ donation' awareness event, or support group gathering for the people on the list, and a single terrible thing could happen to a load of them. Then all you need to wait for is the one person with your organ to die in a desirable way, without you needing to do anything to them: donors must come up fairly often, and avoiding the queue seems like the main problem. 86.142.230.196 (talk) —Preceding undated comment added 03:13, 11 November 2009 (UTC).

Don't forget, the transplant list isn't just a long list of names and when the person at the top gets their organ everyone else moves up one place. You need a good tissue match, similar age, similar size, etc. (there are different requirements for different organs) to receive an organ and tissue matches aren't transitive - Organ A may be suitable for Patient 1 and Patient 2 and Organ B suitable for Patient 1, but that doesn't mean Organ B is suitable for Patient 2. That means the transplant list is actually extremely complicated. Trying to work out where a particular patient is on the list and who is above them is therefore very difficult. What it means to be "at the top" of the list is that you are close enough to the top that when an organ becomes available you might be the highest person that can receive it. It doesn't mean that you will definitely get the next organ to come up. --Tango (talk) 04:01, 11 November 2009 (UTC)

blood type

Do other mammals have blood types in the same manner as the human ABO +/- ? Googlemeister (talk) 17:39, 10 November 2009 (UTC)

Naturally, we have an article. From the point of view of pure biology, humans are just another mammal, so it's not surprising that they are like mammals in this respect as well as almost all others. 87.81.230.195 (talk) 18:03, 10 November 2009 (UTC)

(EC) We live in hope that this is covered at Blood type (non-human). One imagines that Rhesus monkeys, in particular, would be most pissed off to find that they did not. --Tagishsimon (talk) 18:09, 10 November 2009 (UTC)

While the Rhesus antigen was discovered in Rhesus monkeys that doesn't necessarily mean they have it as a blood type. It is only a blood type if some Rhesus monkeys have it and some don't, otherwise it is just an antigen like any other. (At least, that is now I understand the term "blood type".) Are there any Rh- Rhesus monkeys? (Our articles don't seem to say.) --Tango (talk) 18:24, 10 November 2009 (UTC)

Our Rhesus blood group system article needs a lot of work! Purist blood group serologists never talk about the "Rhesus" blood group system. They talk about the Rh system. I believe this originally was done to avoid confusion with the Landsteiner-Wiener blood group system, which was what the original "Rhesus-antibodies" reacted with. The Rh molecules are believed to be ion transporters. People who totally lack Rh antigens get a syndrome of hemolytic anemia and spherocytosis, so the molecule is not absolutely essential for survival. I assume that healthy rhesus monkeys have homologous molecules, since such structures are found pretty much throughout the animal kingdom (see [39]), but as Tango says, to function as antigens to other rhesus monkeys, they also need to be polymorphic, and whether that is the case, I do not know. --NorwegianBlue ^talk

SPC wants you

an any one help me with a mathematical relation between nose radius and feed of a SinglePoint Cutting tool.

See Speeds and feeds, and this textbook entry that's linked from it. Tevildo (talk) 22:10, 10 November 2009 (UTC)

Science and Technology?

What is the relationship between technology and science? Are technology and science the same? <(^_^)> Pokegeek42 (talk) 19:00, 10 November 2009 (UTC)

It may be a good start to look up technology (simplified, the hardware) and science (equally simplified, the software). You are welcome to return with any questions which are still confusing you. --Cookatoo.ergo.ZooM (talk) 19:04, 10 November 2009 (UTC)

The original distinction goes back to the Greek concepts of episteme (knowledge) and techne (craft)—knowing vs. doing. In practice, the distinction is quite blurry, and things that look like "science" in one context look like "technology" in another and vice versa.

The relationship between them, in practice, is complicated. New science can lead to new technology; new technology can lead to new science; new science can have no relation to new technology; new technology can have no relation to new science. --Mr.98 (talk) 19:28, 10 November 2009 (UTC)

science c.1300, "knowledge (of something) acquired by study," also "a particular branch of knowledge," from Latin scientia "knowledge," from scire "to know," probably originally "to separate one thing from another, to distinguish," related to scindere "to cut, divide," or Greek skhizein "to split, rend, cleave". The modern sense of "non-arts studies" is attested from 1678. The distinction is commonly understood as between theoretical truth (Greek episteme) and methods for effecting practical results (tekhne), but science sometimes is used for practical applications and art for applications of skill. The sense of "body of regular or methodical observations or propositions concerning any subject or speculation" is attested from 1725; in 17c.-18c. this was called philosophy.

technology 1615, "discourse or treatise on an art or the arts," from Greek tekhnologia "systematic treatment of an art, craft, or technique," originally referring to grammar, from tekhno- + -logia. The meaning "science of the mechanical and industrial arts" is first recorded 1859. Cuddlyable3 (talk) 19:57, 10 November 2009 (UTC)

I'd say that technology is applied science. Vranak (talk) 19:58, 10 November 2009 (UTC)

Except there is a lot of technology that emerges wholly outside of scientific understanding of what is going on with it, and there is a lot of science that derives from creating new technology. It is a much more synergistic relationship than that. --Mr.98 (talk) 20:32, 10 November 2009 (UTC)

@Mr 98: I have difficulty thinking of "a lot of technology that emerges wholly outside of scientific understanding". Granted, there are various examples of serendipity from boomerangs to the microwave, but most "chance" dicoveries happen in science itself and not in technology. --Cookatoo.ergo.ZooM (talk) 21:12, 10 November 2009 (UTC)

You're only looking at recent technologies. Some of the most important technologies we use, like fire and agriculture, were certainly developed long before there was any scientific understanding of what was going on. StuRat (talk) 23:40, 10 November 2009 (UTC)

Right, that's in particular what I have in mind. There is also a very long tradition of "tinkering" that is done without reference to theoretical knowledge, deep understanding, etc. Edison's choice of the filament for the light bulb was not because he tried a thousand of them (or whatever the number is), not because he really understood which theoretically which one would be best. (Which is not to imply that Edison's "anti-theoretical" aspects aren't somewhat mythical, as they plainly are. But I think it illustrates the point trying to be made.) The Wright Brothers did not have a deep understanding of the physics of heavier-than-air flight. There is quite a lot of technological development that is about engineering "know-how" and not scientific knowledge.--Mr.98 (talk) 01:10, 11 November 2009 (UTC)

You have an extra "not" in your reply which confuses your meaning: "not because he tried a thousand". StuRat (talk) 14:35, 11 November 2009 (UTC)

In the 1870's there was no "Big Book Of Filament Science" from which Edison could have looked up formulas and design principles for lamps. There was basically dustbowl empiricism. Ditto for carbon telephone transmitters. Ditto for the plastic invented to make "Blue Amberol" cylinder records. There was little valid aeronautical science for the Wright brothers to base their aircraft designs on. Science (the leading scientists) claimed that "subdividing the electric light" to allow a small one in each room was impossible just a couple of years before public demonstration of the first practical electric light. Edison (talk) 04:27, 11 November 2009 (UTC)

And it is worth noting, as it is implied above, that answering this question will have a historical dimension. In different times, and in different areas of study, the relationship between science and technology has been somewhat different. (Consider that vast period of human history in which scientific knowledge was if not patently wrong then awfully confused by modern standards.) --Mr.98 (talk) 01:19, 11 November 2009 (UTC)

Another good example of technology without the underlying science is the "contagion theory of disease", which allowed people to implement quarantines and other safety measures (like filling in contaminated wells), long before the specific bacteria or virus was identified. Leper colonies, for example, existed back in Biblical times. StuRat (talk) 14:39, 11 November 2009 (UTC)

Rhesus antigens other than D

There are five antigens in the Rhesus blood group system: C, D, E, c and e. Most of time people only talk about the D antigen (that is the one "Rh+" or "Rh-" refers to). Why don't we worry about the others? Do people without those antigens not produce antibodies to them for some reason? Our article doesn't seem to address this issue. --Tango (talk) 22:30, 10 November 2009 (UTC)

There are, actually, many more, but those are the common variants. The D antigen is special in that it is a more immunogenic than the others, and much more likely to cause hemolytic disease of the newborn, but people get immunized against C, c, E and e as well. If they receive blood with the antigen that they're immunized against, a hemolytic transfusion reaction is likely to occur. Pretransfusion testing (for patients that may need blood during their stay in hospital) includes screening against all common blood group antibodies. --NorwegianBlue ^talk 21:03, 11 November 2009 (UTC)

Ok, so a full cross-match will involve checking for all the antigens, but D causes bigger problems so if you only have time to worry about one you worry about that one? --Tango (talk) 21:09, 11 November 2009 (UTC)

Trauma centers etc. have a small supply of O Rh(D) negative erythrocyte concentrates that may be issued in emergency situations, before the blood type is known and antibody screening and/or crossmatching have been performed. If the patient has an anti-c, that can cause problems, because O Rh(D) negative blood is almost always Rh(c) positive. However, in such emergency situations, not getting the blood in time may be a greater threat to the patient than the transfusion reaction. --NorwegianBlue ^talk 21:38, 11 November 2009 (UTC)

It's basically been said above, but here are links to relevant articles, in case anyone is still interested:

hemolytic disease of the newborn

hydrops fetalis

Rh disease

Rho(D) immune globulin

--- Medical geneticist (talk) 00:52, 12 November 2009 (UTC)

Shipping a private vehicle from the US to China

I would be very grateful if someone could help me locate information regarding shipping a private vehicle from the US to China. I haven't been able to turn up anything regarding rates, regulations, even approximate transit times. 218.25.32.210 (talk) 02:02, 11 November 2009 (UTC)

I don't have specifics - but I know it costs a couple of thousand dollars to ship a small car from Australia to the US - and maybe fifteen hundred to ship to the US from UK. The distances are kinda comparable. The saving grace might be that the US imports a VAST amount of bulky stuff from China - and exports a much smaller amount of more compact stuff back again. It follows that there are shiploads of mostly empty containers going from the US to China. The law of supply and demand says that it should be pretty cheap to ship your car. I know it takes about a month to ship a car from Australia - China ought to be similar. Regulations...sheesh...who knows?! It's a minefield. China may have easier regs than the US - but coming back in the opposite direction (from UK/Australia INTO the US), I wouldn't consider doing it unless the car was an 'antique' that would be exempt from emissions control & safety regulations, etc. SteveBaker (talk) 02:45, 11 November 2009 (UTC)

And that's just shipping charges. I think Israel charges 100% tax on US-made cars. DRosenbach ^{(Talk | Contribs)} 04:01, 11 November 2009 (UTC)

Thanks for the estimates, Steve. Foreigners in China actually get one tax-free import each last I checked. As you can imagine, there are all sorts of shady businesses here constantly bombarding us with offers to "buy" that free entry so that they can import a {insert suitably ultraexpensive brand} car under your name. The going rate in my part of the country is $3000~$4000, (legality aside) not bad at all if you're only here for a year or two and wouldn't have taken advantage of that right to begin with. 218.25.32.210 (talk) 04:58, 11 November 2009 (UTC)

Just a note here; Wikipedia does not, in any way, condone any illegal activity. —Preceding unsigned comment added by 157.203.42.175 (talk) 10:46, 11 November 2009 (UTC)

exercising in smog

What's better for your health: Living in a place with high air pollution (smog) and trying not to "move" much, or moderately exercising although that implies breathing in more polluted air more deeply? Which would more likely improve your life quality and life expectancy in the long run?

I'm interested both theoretically and pragmatically: What would you consider for such a comparison? Only the harm to the lung vs. "all" benefits of exercising, or what else? To what extent does the baseline matter--e.g., is walking a total of half a mile and some stairs enough to give up further exercise? And down to earth: What's the rule of thumb you'd use to decide?

I'm asking because my friend (lower 30s, without health or weight problems so far) lives in Cairo, a city with considerable smog, and without easy-enough access to less-polluted areas for exercising. What would be your advice? Any thoughts? --Thanks for answering (talk) 02:07, 11 November 2009 (UTC) PS: Yes, I know you're not giving medical advice, yada-yada. But it's not exactly a question for which to see a doctor. :)

It's really impossible to generalize - and we don't know the nature of the pollution, the density of it, the need for the person to have additional exercise, what time is spent outdoors, what time indoors, whether filtered airconditioning is available, the age of the person, how long is spend exercising...there are WAY too many variables.

However, I'd ask you this: What is the proportion of the day you'd spend exercising? If you exercised for (let's say) 1 hour per day - which is arguably more than is really needed for normal health - and if you breathed (let's say) twice as fast and just as deeply during that time - then the amount of additional exposure you're getting by exercising is only around 5% more than you'd get if you didn't exercise. That seems rather little compared to the benefits of regular exercise. If you did your exercise in someplace with more filtered air (indoors - perhaps someplace with an airconditioner) - then you could easily control the amount of pollutants being cycled through the lungs during periods of high respiration. SteveBaker (talk) 02:32, 11 November 2009 (UTC)

"if you breathed (let's say) twice as fast and just as deeply during that time"

— SteveBaker

During exertion, tidal volume increases before respiratory rate. During heavy exertion, minute volume can reach 60 litres per minute, compared to about six litres per minute at rest. Axl ¤ [Talk] 08:20, 11 November 2009 (UTC)

This study examined the effect of acidic fog (sulphuric acid). They found only mild, short-term irritation in the lungs. Axl ¤ [Talk] 08:38, 11 November 2009 (UTC)

There is only limited information about this matter. Here are a couple of interesting articles, although they don't directly answer your question. My opinion (original research): there are only a few adverse effects from exercising in the polluted environment. It's probably better to take exercise in this situation, than not to take exercise. Axl ¤ [Talk] 08:45, 11 November 2009 (UTC)

How did you find the articles, Axl? Any particular search tool? ... - Thanks to both of you for your hard facts and speculations! Very interesting! And not being an (active) AC user, I didn't even know that they can have filters. :) Although then we probably get into the additional problem if the ACs are well-maintained or if they may spread additional unhealthy stuff like bacteria...

Steve Baker, type and density of pollution in Cairo don't seem to be well-studied (anyone needs a research topic? :))... but 2004 World Bank data found that Cairo had the highest amount of particular matter per m³ worldwide, and other stats weren't much better. It scored 10th for sulfur dioxides 1995-2001 (though I doubt that's still up-to-date information), and no information was published on nitrogen dioxides, but that would likely be pretty elevated as well. No idea if pollution is relatively evenly spread throughout the city, but Wikipedia says that Cairo's pollution is in part caused by cars, so presumably it is. ... Hmhm, you learn something new every day. :) So if you should have further facts or thoughts, keep them coming. --Thanks for answering (talk) 11:22, 11 November 2009 (UTC)

PS: Just in case someone else reads this and jumps to conclusions: Yes, the articles only found throat irritations, but that was because they were only looking for those. Smog has (for right or wrong) been compared to smoking cigarettes, and if you compare throat irritations of smokers and non-smokers, you'd find the same: only throat irritations. If you look at more severe long-term effects, however, you'll find more... Smog#Health_effects gives a little intro, but I'm not sure it covers all research there is about long-term effects... --Thanks for answering (talk) 14:02, 11 November 2009 (UTC)

According to the 2006 research Smog and Smug there is negative correlation between smog and smugness levels. I afraid that your friend have no other choice but to continue practice under heavy smog conditions, it's much safer than becoming smug.--Gilisa (talk) 16:38, 11 November 2009 (UTC)

"How did you find the articles, Axl?" I use PubMed. Axl ¤ [Talk] 18:35, 11 November 2009 (UTC)

November 11

Electromagnetic Fields

A cat carrying a house mouse. Cuddlyable3 (talk) 17:27, 11 November 2009 (UTC)

I have a mouse problem and have considered buying a 2-in-1 mouse repeller - that uses an electromagnetic signal and an ultrasonic one (I've heard that they may not work; but with a money back guarantee I figure I've got nothing to lose). My flatmate is paranoid of such devices (despite living around mobile phones etc.) - does anyone have a link to a reputable website or verifiable Wikipedia page with some information supporting the safety of such devices? Ideally not a manufacturer's website, if possible. Thanks

I know this does not answer your question, but why not use a good old-fashioned mousetrap? They have never let me down, and you can get humane ones very easily, at least in the UK (which are unfortunately not included in the article).--Shantavira|^{feed me} 09:44, 11 November 2009 (UTC)

Thanks for the suggestion; one of the reasons I'm trying to use these deterrents (and avoiding traps and poison) is that I'm not convinced I can kill them faster than they can reproduce. I don't like the idea of clearing out loads of mouse corpses either, though I don't think that would be a problem as the damn things ignore the traps I have put down. —Preceding unsigned comment added by 157.203.42.175 (talk) 09:56, 11 November 2009 (UTC)

Well, the Wikipedia page is Electronic pest control, but that doesn't go into the safety. Electromagnetic radiation and health appears to be thoroughly referenced and might be of some use. AlmostReadytoFly (talk) 10:20, 11 November 2009 (UTC)

Thanks, this was particularly useful, especially the WHO references on the Electromagnetic radiation and health page. —Preceding unsigned comment added by 157.203.42.175 (talk) 10:44, 11 November 2009 (UTC)

I've tried 3 methods of mouse control, with varying success:

1) Traditional "break their necks" mouse traps. I never caught a single mouse with those.

2) Poison. This killed some mice, which I later smelled decomposing somewhere (one in the ceiling), and just blinded others, which then stumbled around my house until I did them in personally. Very messy and very cruel. The poison also stinks, and the decomposing mice gave off the chemical smell as well as the usual dead mouse smell.

3) Glue boards (with some grain as bait in the center). This trapped all the mice. Note that they are exceedingly cruel in that one mouse ripped off half of his face trying to escape. You also have to finish them off yourself, which I do by drowning (they drown in about 12 seconds). However, they solved the mouse problem quickly. Glue boards also catch insects and spiders, which is a nice side benefit, but does mean you need to add fresh boards every once in a while, as those coated with dead insects no longer can catch a mouse.

Also note that you need to figure out how mice are getting in and block that route. In my case we have an enclosed back porch which they apparently can enter, and from there they accessed the house through a door left open for ventilation. I now keep that door closed all the times. StuRat (talk) 14:20, 11 November 2009 (UTC)

Victor and RatZapper make electronic computerized mousetraps that are unbeatable. They operate on a few AA or C batteries. The Victor model sells for circa $17 at Amazon or in hardware stores. They have a microcomputer which uses the resistance between floor grids in an enclosed chamber to detect the presence of a rodent, then they apply a lethal jolt of electricity. The RatZapper allows a remote indicator to tell you when it has got one. The Victor has a blinking LED on top when it has got one. You dump out the carcass and push the reset button, then kill the next one. They do not steal the bait, nor do they spring the trap and get away as is common in spring traps. They do not get stuck and suffer like in glue traps. There is no fantasy of catching them in a live trap and releasing them outside (in which case they may be back inside before you are). Edison (talk) 15:27, 11 November 2009 (UTC)

We have some mouse traps we bought in the UK - they are slightly angled square cross-section tubes - sealed at one end with some bait (peanut butter works well) and with a trap-door on the other end. As the mouse walks into the trap, the tube kinda tips over (it's hard to explain in words) and the trapdoor is sprung. The mouse is perfectly OK inside and even has to peanut butter to enjoy. You take the tube to someplace a few miles from your house, unlock the trap door and up-end it and the mouse scurries away, none-the-worse for the experience. The trap can then be re-baited and re-used as many times as you need. So long as there aren't long-distance "homing mice" in your area you'll do fine! We caught several mice that way...until we moved out into the countryside where the rattlesnakes take care of the mice and all you have to worry about is not stepping on the snakes! SteveBaker (talk) 17:02, 11 November 2009 (UTC)

And for every mouse you release 5 miles from your house, someone will catch a mouse and release it by your house. This probably improves the genetics of the mice by reducing inbreeding, but it in no way reduces the number of mice entering homes. Edison (talk) 20:17, 11 November 2009 (UTC)

I would hope people don't release them near other people's houses... You go 5 miles away to the middle of a field or wood or, as a last resort, a park. --Tango (talk) 21:20, 11 November 2009 (UTC)

Or the exercise area of the local cat shelter. Googlemeister (talk) 21:28, 11 November 2009 (UTC)

Living in a messy student house a few years ago, I tried the live mouse trap described by SteveBaker, with mixed results - two mice went straight in, but there were one or two more which never did. An ultrasonic deterrent had no effect at all; I saw one mouse about a foot away from it. Eventually, just cleaning everything thoroughly and ensuring that all food was sealed away seemed to persuade them to leave. Warofdreams talk 02:26, 12 November 2009 (UTC)

Can you catch them faster than they reproduce? It depends, I imagine, but I once had a major mouse problem that got solved in literally two nights with some peanut butter and old-fashioned spring traps. They were, no joke, pretty much jumping onto the traps as far as I refilled them. (I had originally planned to not re-use the traps—just to dump them with the mice into the trash—but it became clear that there were way too many mice to do that without buying more traps.) I think over the course of two nights about a dozen mice wandered onto the traps we put out (sometimes while we were still in the room!!!). We never had any more mice trouble after that. We attribute it to the mice being not too bright and liking peanut butter a whole lot, and I know other people have had mixed results with such traps. But in our case, we were definitely able to get a handle on the mouse problem with traps alone. Horrifically, the mice we caught got smaller and smaller as things went on. "Mom, Dad, where are you? OH! Peanut butter!" --Mr.98 (talk) 21:57, 11 November 2009 (UTC)

• Mice don't like the smell of peppermint oil. Don't know why, they just don't. Apparently fabric softener sheets smell nasty to them too. Also, fine steel wool to block up the holes they use is a good deterrent. For a humane trap, rig up a tipping tube trap, like this. Fences&Windows 03:21, 12 November 2009 (UTC)

Honey sugar

Think of a completely isolated country that has plenty of honey and very little if any sugar cane. Can they use their honey, of any type/flower source, to make something akin to granulated sugar, perhaps by leaving it in the sun spread flat for a few days? Could you use whatever they get through that to make toffee and that lot, or to put in a mix to make solid chocolate, and what might the difference in taste be? Lady BlahDeBlah (talk) 12:55, 11 November 2009 (UTC)

According to Honey, honey derives its sweetness from glucose and fructose monosaccharide. Since table sugar is sucrose; a disaccharide, (composed of fructose and glucose) it is theoretically possible to produce table sugar from honey, probably through polymerisation, ultimately likely to be through an industrial process. It's unlikely that honey would have a 50:50 split of glucose:fructose and therefore there would likely be waste of one of the monomers. Polymerisation generally requires the removal of water through enzymatic interation with the monomers, but I doubt this would occur were honey to be left out in the sun. With the prevelence of sugar cane and sugar beet derived sugars, I have doubts about whether this would even be an economically viable process. —Preceding unsigned comment added by 157.203.42.175 (talk) 13:08, 11 November 2009 (UTC)

Okay, so actual chemically-identical proper granulated sugar is impossible. That's fine. This country (which is a setting I am building upon) is renaissance-medieval with no industrial revolution in sight nor any external trade. Basically what I'm asking is can honey or dried/solid honey (or whatever-happens-to-sun-dried-honey) be used like cane sugar to make toffee, to put in tea, to make icing with, to sweeten eating chocolate with, etc, and how would it impact the taste? Lady BlahDeBlah (talk) 13:16, 11 November 2009 (UTC)

If you simply dried it you would just have dehydrated honey, and it would still taste like honey when you rehydrated it. So it would affect the taste of whatever you added it to. For many things, that would be OK, but some foods with a rather subtle taste might be overwhelmed by the taste of honey. It is certainly possible to extract glucose and fructose from honey, and these would be much more like table sugar, in that they would add sweetness with hardly any other flavor. StuRat (talk) 14:04, 11 November 2009 (UTC)

Would extracting the -oses be possible in the society's technology level I have described, though? Lady BlahDeBlah (talk) 14:19, 11 November 2009 (UTC)

Probably not. However, it wouldn't be beyond the realms of reasonability to suggest that dehydrated honey would make a substitute for what you've suggested. Honey would likely crystallise before supporting the growth of micro organisms (due to a low water activity) and could be expected to make reasonably good baked goods, perhaps with slightly different properties (cookies might be a lot more gooey, for instance). Don't forget that if this is a fictional universe, your characters would (presumably) have no appreciation of the qualities of table sugar and therefore be unaccustomed to anything else. Overpoweringly honey-tasting baked goods would be the norm if that were the only sweetener. —Preceding unsigned comment added by 157.203.42.175 (talk) 14:21, 11 November 2009 (UTC)

The transition from refined sugar from sugar cane to high fructose corn syrup in much of the sweetened food in the United States has shown that the population at large either adapts or does not notice some changes to the sweetening agent. Nimur (talk) 15:44, 11 November 2009 (UTC)

In a hypothetical world, you'd imagine that people would adjust their entire cuisine to the idea that sweet things have that honey flavor - so perhaps they'd never think to inject sweetness into subtly flavored foods - just as we don't put chili peppers into subtly flavored dishes. They would not even be aware that it was an issue. SteveBaker (talk) 16:53, 11 November 2009 (UTC)

As far as I know, refined sugar is a relative newcomer in some cuisines. For millennia, people around the Mediterranean have used honey, as well as dates, grapes, carob, figs and such (and Lead(II) acetate in ancient Rome) to sweeten their respective cuisine. Sugarcane was only introduced in the Mediterranean by Arabs after the advent of Islam, see Sugarcane. For example, the Seven Species of staple foods of the Land of Israel include grapes, figs, pomegranates, and dates, but not sugarcane; milk and honey are also mentioned explicitly. --Dr Dima (talk) 19:14, 11 November 2009 (UTC)

Speed of gravitons in a black hole?

What is the speed of the hypothetical particle which carries gravitational force, the graviton? If the graviton is limited by the speed of light, how can a black hole exist? The gravitons would need to move faster then light to escape the black hole, and if they didn't there would be no black hole in the first place? Are they superluminal particles? Could they be used to violate causality? —Preceding unsigned comment added by 80.2.204.230 (talk) 13:03, 11 November 2009 (UTC)

I'm not sure they "would need to move faster than light to escape the black hole"—presumably the graviton itself would not be affected by gravitational force, per se, but be the carrier of gravitational force. But perhaps someone else with a deeper knowledge can explain further. --Mr.98 (talk) 13:56, 11 November 2009 (UTC)

Pretty much any theory of gravitons would require that they travel at the speed of light and be influenced by the topology of space-time. In other words, they would pretty much have to be affected by gravity in addition to being the cause of gravitational force. Making that self-consistent with our large scale understanding of the universe is one of the reasons that a quantum theory of gravity has remained elusive. Dragons flight (talk) 16:11, 11 November 2009 (UTC)

Building off the above, the speed of gravity is well understood to be the speed of light. Regardless of the existence or properties of the graviton, it's empirically clear that (1) black holes exist despite the speed limit of gravity (or, if you prefer, the propagation of gravity is not restricted by a gravity field) and (2) gravity is subject to the same cosmic speed limit as everything else. Causality remains quite safe. Note also that causality may aggressively defend itself if you start getting too close to violating it. — Lomn 16:00, 11 November 2009 (UTC)

There was a similar question asked very recently. As I said there, the gravitational field of a black hole doesn't come from inside; it's actually left over from before the black hole formed. The answer to "how is this explained with virtual gravitons?" is that the virtual particle approach to forces isn't always useful and this is probably one of the times when it's not useful. -- BenRG (talk) 01:34, 12 November 2009 (UTC)

The structure of Einstein's general theory of relativity requires that everything is affected by gravity. (Specifically, the presence and strength of a gravitational field in a particular location depends on how you choose coordinates, so it is arbitrary. It therefore makes no sense to say 'not affected by gravity,' since how such a particle would move would depend on which coordinates were used by the physicist to describe spacetime.) 70.26.152.160 (talk) 04:39, 12 November 2009 (UTC)

heptane, 3-methylene-

Is there any chemical information available about heptane, 3-methylene- ?? I am looking for a CAS# and/or a MSDS if possible. Timetraveler 013 (talk) 13:04, 11 November 2009 (UTC)

Is this the same compound than 2-Ethyl-1-hexene (CAS 1632-16-29 ?--Stone (talk) 13:57, 11 November 2009 (UTC)

Iron ore question

Hello. I left a post here a bit ago (and linked to it at Talk:Iron) yet it hasn't received any response, so I thought someone here may have some information that could help answer the question. Thanks. The Seeker 4 Talk 16:36, 11 November 2009 (UTC)

Thats a good question, but I've no good answer. All I can tell is that iron made tools from 2000BC were found in what was once Mesopotamia and that iron carburizing was known process in the Middle East at about 1200BC (this could be a byproduct discovery of iron production process). I guess that they just identified minerals rich with iron ore by sight. But I will look for additional information on the web to answer this.--Gilisa (talk) 17:06, 11 November 2009 (UTC)

• I found this book[40]. Seems like it should include an answer.--Gilisa (talk) 17:14, 11 November 2009 (UTC)

The simplest way would be "look for rust". Seriously, iron ore readily oxidizes to form iron oxide (rust), so there will be the characteristic reddish color of rust wherever you have iron ore. StuRat (talk) 02:29, 12 November 2009 (UTC)

Do crocodiles care for their young? (Schnappi)

Do real-life crocodiles care for their young? Schnappi's parents do, but Schnappi is make-believe. Mike R (talk) 20:06, 11 November 2009 (UTC)

To certain extent. The mommy corcodile carry her offsprings in her mouth untill they are mautre enough, before that, when they are still in the lair, she come immediately when they sound stress signals. However, when they are mature she send them away, and they better keep it this way for their own safty.--Gilisa (talk) 20:53, 11 November 2009 (UTC)

There's a short passage about it in a book on crocodiles here. They guard the nest, etc. It's mainly the female, but the male chips in occasionally. Fences&Windows 03:02, 12 November 2009 (UTC)

Diet of crocodile hatchlings (also Schnappi related)

Do real-life baby crocodiles eat flies, like Schnappi does? Flies are Schnappi's favorite thing to eat. Mike R (talk) 20:33, 11 November 2009 (UTC)

Nile_crocodile#Diet_and_eating_behavior mentions hatchlings do eat insects among other things. I don't know if that includes flies specifically, but I doubt they are very picky. Rckrone (talk) 21:51, 11 November 2009 (UTC)

Thank you for the link to Nile crocodile. I had just looked at Crocodile and found it lacking. And Nile crocodile is Schnappi's species (Ich bin Schnappi, das kleine Krokodil / Komm aus Ägypten, das liegt direkt am Nil)

I've added Nile crocodile to Crocodile#See_also Mitch Ames (talk) 00:43, 12 November 2009 (UTC)

November 12

Distance

I would like to know what the distance is from the Congo to New Orleans? 00:06, 12 November 2009 (UTC)67.48.17.69 (talk)

According to indo.com, the distance from Kinshasa to New Orleans is 7294 miles. Of course it depends on what point on the Congo you are asking about. Looie496 (talk) 00:33, 12 November 2009 (UTC)

Also see this (unless you mean Congo Square :) hydnjo (talk) 00:56, 12 November 2009 (UTC)

Laser apperance

What causes that strange grainy look that the light produced by most commercial lasers has? Horselover Frost (talk) 00:17, 12 November 2009 (UTC)

Laser light is normally invisible, as it is coherent light that's being aimed somewhere other than your eyeball. If there's dust or fog in the air, the tiny particles of dust or fog scatter the light so that some of it enters your eyeball and you can see it. That grainy look is because the person operating the laser has tossed some dust in the air so that you can see the laser beam. Comet Tuttle (talk) 00:20, 12 November 2009 (UTC)

I should have been more specific. I'm aware laser light in the air is invisible (I'm the one shining the laser). I was referring to the light reflected off a surface. I.e. I take a laser and shine it at a wall, the spot it makes has a grainy appearance, as opposed to, say, shining a flashlight on the same wall. Horselover Frost (talk) 00:25, 12 November 2009 (UTC)

I would guess (and this is just a guess) that it is because the wall is uneven. Different parts of it reflect differently, resulting in the grainy appearance. When you shine a flashlight at a wall each bit of the wall is illuminated from different angles from different bits of the flashlight. That means what you see is an average of how that bit of wall reflects from different angles. That results in a more even appearance. --Tango (talk) 00:40, 12 November 2009 (UTC)

See speckle pattern. TenOfAllTrades(talk) 00:49, 12 November 2009 (UTC)

A-A bonds are weaker than A-B bonds, which are in turn weaker than B-B bonds

So would a small amount of A be weakly soluble in B, before a separate phase of pure A starts accumulating?

Basically I want to also connect this to the idea of polar covalent bonding versus Van der Waals. Thus, are polar compounds always slightly soluble in nonpolar compounds, but not the other way round? That is, if you had a phase diagram of say, oil and water, you might find an oil+water single phase at maybe 0.1% water by volume, but after that, water starts accumulating as a separate phase. However, oil can't break hydrogen bonding, so oil never dissolves in water, not even at 0.001% levels.

Say you had a eutectic solution of alpha + beta phases, which are solutions of A and B. Could this arise if A-A bonds were weaker than A-B bonds, which were in turn weaker than B-B bonds? John Riemann Soong (talk) 05:43, 12 November 2009 (UTC)