Wikipedia:Reference desk/Archives/Science/2009 November 6

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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)