Wikipedia:Reference desk/Archives/Science/2014 October 19

= October 19 =

types of the cells
Is it correct to say that the body cells be catalogued according to the tissues? 194.114.146.227 (talk) 00:09, 19 October 2014 (UTC)


 * See List of distinct cell types in the adult human body. -- Jayron  32  00:12, 19 October 2014 (UTC)


 * You can catalog them however you like, but by tissue type certainly seems like an obvious choice. StuRat (talk) 00:13, 19 October 2014 (UTC)


 * You might also be interested in some of the info at histology. SemanticMantis (talk) 13:41, 20 October 2014 (UTC)

Why Do Sugary Foods Cause Instant Discomfort in Teeth with Cavities?
I have a set of cavities in my back teeth, as soon as I eat sugary foods, they hurt. I understand why sugar causes cavities, I understand how chewing (or irritants, like hot sauce) can cause pain, but I don't see why a piece of candy should cause instant discomfort. My understanding is that bacteria consuming sugar generates acid, but I would assume that that does not happen immediately - and I only experience discomfort in my cavities, not in healthy teeth. --I am not asking for medical advice, the solution is to have the dentist fill them; I'm just curious about what is happening since it doesn't make much sense to me. Thank you for any help:-)Phoenixia1177 (talk) 01:50, 19 October 2014 (UTC)


 * While we can't give medical advise, there is quite a bit of literature on the internet about this including in our own dentin hypersensitivity article. Dismas |(talk) 02:19, 19 October 2014 (UTC)


 * When I looked for an answer, dentin sensitivity is what I came across, but I don't understand why sugar causes pain (and only in those specific teeth) - sugar isn't an irritant, so I don't understand what it is that causes the pain. If I rub sugar on a cut, it won't hurt, so why should sugar cause pain in that case, what is it actually doing? Thank you for the reply - I definitely don't want advice, I only include my experience because that is how I'm aware of it, I don't imagine anyone can tell me anything besides "see a dentist" anyway. Thank you for assuming good faith, and for your response:-)Phoenixia1177 (talk) 02:34, 19 October 2014 (UTC)


 * I don't think it's just teeth with cavities. Pecan pie does something like that to my teeth, and they are cavity free.  I think it has to do with high-fructose corn syrup, not normal sugar. StuRat (talk) 02:44, 19 October 2014 (UTC)


 * I believe that high-fructose corn syrup is very much an American thing, much less common in other parts of the world. Sugar sensitivity in teeth is a world wide phenomenon. HiLo48 (talk) 03:02, 19 October 2014 (UTC)


 * I've read that that can be the case for some people, but in my case, it is only teeth with cavities (I got bored and rubbed various substances on my teeth earlier, one row has cavities, one does not, only the row with cavities hurt from sugary substances).Phoenixia1177 (talk) 02:48, 19 October 2014 (UTC)


 * This paper seems informative and relevant, but I'm not interested enough to read it thoroughly. I could be wrong. Maybe you'd like to try? Also keep in mind that sugary food contains far more than just sugar. Don't immediately blame the likely suspect. InedibleHulk (talk) 14:20, 19 October 2014 (UTC)

When you have sensitive teeth there are microscopic channels between the tooth surface and the nerve endings. It would appear from our own article and the paper linked above that sugar causes osmotic changes in the channels that are interpreted as pain. And from my own OR you tend to get sensitive teeth as you get older due to wearing away of the enamel and gum recession exposing the more sensitive areas. Toothpaste for sensitive teeth works by temporarily blocking these channels. I just wish someone would come up with a varnish that permanently coats your teeth and cures the problem. Richerman   (talk) 14:47, 19 October 2014 (UTC)


 * It's not permanent, but see dental sealant. Matt Deres (talk) 16:53, 19 October 2014 (UTC)


 * That seems to be mainly for sealing fissures in the biting surfaces of back teeth. I was thinking of something that you could paint over all the teeth to cure the problem - even if it had to be renewed every so often it would be an improvement, but of course on the front teeth it would have to look ok as well. I'm sure if it was that easy someone would have come up with it by now. Richerman    (talk) 17:14, 19 October 2014 (UTC)


 * I have some personal skepticism that such things are really needed since where I've had recessions they seem to lose sensitivity gradually on their own. I looked up "self-resolving" and found things like this that tend to back up that perception, though I didn't look into it properly.  I can't help but think that if such an elaborate network of channels exists, and sensitivity routinely arises, there must be a reason for it. Wnt (talk) 22:02, 19 October 2014 (UTC)


 * If you think that sugar leads pain, then the sweet taste of a candy may itself be enough to cause or amplify pain. Count Iblis (talk) 19:01, 23 October 2014 (UTC)

I need information about a cross -pollinated fruit named a "brugnon".
I was told that: 1) it was a cross-pollination between a plum and a peach. 2) This was accomplished by french scientists; hence it's name "brugnon". 3)It has also been called a "White Nectarine". Any information to corroborate or refute this report would be very helpful. Thank you.24.45.51.245 (talk) 02:49, 19 October 2014 (UTC)
 * Google "brugnon" and some things turn up. The first was this article in the French Wikipedia, if that's any help: ←Baseball Bugs What's up, Doc? carrots→ 03:16, 19 October 2014 (UTC)


 * Ah-ha! This looks like a job for someone well versed in both French and Botany. Until that person shows up, you'll have to settle for what I've been able to find out.
 * The short answer is that brugnon is the French word for a kind of nectarine.


 * OK, longer version: there are lots of varieties of peach (Prunus persica): different coloured skin, different coloured flesh, some with a rough stone and so on. It's like dogs: they come in all shapes and sizes, but they are still the same species.
 * One group of the varieties of peach are smooth-skinned, without the "peach fuzz".
 * In English, a non-fuzzy variety of peach is called a nectarine (Prunus persica var. nucipersica)
 * In French, a non-fuzzy variety of peach is called
 * - a nectarine, if the flesh doesn't strongly adhere to the stone (Prunus persica var. nucipersica again)
 * - a brugnon, if the flesh does strongly adhere to the stone (Prunus persica var. nucipersica and again)
 * I got most of that info about it in this article from L'Express (France). In French the title is Pêches, nectarines, brugnons: les confondre c'est pêcher! (Peaches, nectarines, brugnons: the confusion that is peaches [generically speaking]!) Google translates this as "Peaches, nectarines, nectarines: confused is fishing!", translating brugnons as "nectarines". The idea that nectarines are the result of a cross between plums and peaches is also addressed in the article: "On dit souvent que les nectarines et les brugnons seraient le fruit d'un croisement entre un prunier et un pêcher. Eh bien non, c'est faux!" (It is sometimes said that nectarines and brugnons were the result of a cross between plums and peaches. Hell no!)
 * I'll be back to add some pictures after this brief commercial break (ie: once I figure out how the wiki-code for them works.)
 * Peter in Australia aka --Shirt58 (talk) 08:26, 19 October 2014 (UTC)


 * Caveat: I have never studied French and I am not a Botanist. But I am a lawyer, and it's our job to know everything about everything. Or at least try and convince people that we do.


 * Note that the distinction can be made in English by calling them "freestone nectarines" (just "nectarines" in French) and "clingstone nectarines" ("brugnons" in French): . There's also a “semi-freestone nectarine", but I don't know what the French call that.  StuRat (talk) 17:19, 19 October 2014 (UTC)


 * I realise that the two varieties are the result of different hybridisations, but is there a significant difference in flavour. I think I've probably eaten both without appreciating that there was a difference.  Does one have a firmer, whiter flesh, or is that just a difference in ripeness?    D b f i r s   19:21, 19 October 2014 (UTC)
 * A difference of flavor for "whiter" suggests the idea of white vs yellow noted at Peach. DMacks (talk) 05:11, 20 October 2014 (UTC)
 * Thanks, it seems that they are all just varieties of peaches, not crosses at all.   D b f i r s   11:39, 20 October 2014 (UTC)


 * See also Nectaplum, Peacotum, Plumcot, Apriplum, Pluot, or Aprium etc. Given the endless varieties of hybridization, and the fact that the names are of often trademarked, deciding whether brugnon is an exact translation of any of these, though, may well be a hopeless exercise. Abecedare (talk) 19:33, 19 October 2014 (UTC)
 * Teh face-palm. So while these somewhat obscure hybrids have stand-alone pages, the English language Wikipedia article Peach is a mix of two commercially and culinary distinguished things. That's like having one article called "Labrador Retriever" about the Labrador Retriever and the Golden Retriever on the basis that a Golden Retriever is just a long-haired version of the Labrador. --Shirt58 (talk) 10:34, 20 October 2014 (UTC)


 * The word pêcher does mean "to fish", but it also refers to the peach tree itself. Compare pommier, "appple tree". μηδείς (talk) 03:27, 20 October 2014 (UTC)
 * Thanks μηδείς. I was aware of the G-Trans fuddle thanks to pesca/pesce in italiano, but didn't know about the suffix. So does "Ferrier" mean "iron-tree"? --Shirt58 (talk) 11:00, 20 October 2014 (UTC)


 * Here's a neat graphic, not quite what you're looking for but... Wnt (talk) 20:05, 20 October 2014 (UTC)


 * And credit to User:Shirt58 as I missed prunier in the quote above. In Spanish the difference between the fruit and the tree is like Italian, apparently, manzana = apple, manzano = apple tree, while manzanar = apple orchard. μηδείς (talk) 23:49, 20 October 2014 (UTC)

Are small bodies (<C/2013 A1 size) less likely to be active comets than 1-3 km stuff? How does this vary with distance?
You might think so, a small enough comet would be used up in only one orbit and become an asteroid, while Halley has been spectacular for dozens of orbits. There's a power law with size in the Oort Cloud, though. Much more small comets there. Also, porous comet dirt material is probably a very good insulator. Once all the vaporizable matter is gone, there might be perfectly good ice left inside where the heat can't reach before the surface gets cold again. This would mean that for enough size the amount of comet fuel available isn't width cubed but approaches width squared. L And large, not tiny, comets are more liable to be torn apart if they get close to a major body. I don't know what the sum of all these effects is.

As for the second question, there are few known asteroids close to the Sun or between Jupiter Trojans and the Kuiper belt. Comets predominate there (even if not active). How much of this is observation bias? (Venus to Mars asteroids pass close (<.4 AU) to Earth eventually, some very close. Mercury-huggers never would, and share the inferior planet's observation difficulties. A 20,000 years comet only gets recorded close to Earth if it's lucky. The closer a comet is to the Sun, the brighter it is, it brightens more than an inert reflector.)

Can comets be arbitrarily small? Sagittarian Milky Way (talk) 05:35, 19 October 2014 (UTC)


 * I advise you to read Comet, which gets into some good detail on the nature of those critters. ←Baseball Bugs What's up, Doc? carrots→ 11:25, 20 October 2014 (UTC)

Is all so-called mental illness just anxiety?
Has anyone ever suggested that all diagnoses of mental illness (be it schizophrenia, bipolar disorder, depression, the once popular multiple personality disorder...) are all just anxiety and, in the end, pretty much the same thing? What I'm asking/trying to ask is probably very unclear, so if that's the case, please let me know and I'll try to clarify whatever needs to be clarified. Thanks. --Schweinchen (talk) 13:37, 19 October 2014 (UTC)
 * This is very roughly what the practitioners of Dianetics claim. I'm unaware of any serious scientist or doctor outside the Church of Scientology accepting that the theory has any validity. Mogism (talk) 13:41, 19 October 2014 (UTC)


 * Probably been said. But if you compare the official diagnostic criteria, it's not hard to see some differences. You don't need to be delusional to get a depression label, and if you're constantly worried about your self, you're not disassociated from it. InedibleHulk (talk) 13:46, 19 October 2014 (UTC)


 * There are different syndromes like OCD which causes almost tic-like behaviors, PTSD that might cause night terrors, or schizophrenia which may cause paranoia and delusions. These are quite clearly distinguishable.  Different drugs related to things like dopamine and serotonin are used to treat them when possible.  Anxiety is more of a symptom that while it can occur on its own General anxiety disorder may also accompany other disorders the way any sense of being out of control might.  But just as we wouldn't say that pancreatic cancer and pregnancy are the same thing because they both are often accompanied by diabetes, we wouldn't say all mental illness is just anxiety. μηδείς (talk) 16:44, 19 October 2014 (UTC)
 * Oddly enough, if you're on pills for anything and these pills cause night terrors, you are ineligible for "night terror disorder". Same goes if the terror is caused by an actual medical condition. If your doctor finds you don't have a medical condition causing it, you do get medicine. You don't even need to take their drugs to feel anxious about drug companies. An awareness is often enough. InedibleHulk (talk) 16:59, 19 October 2014 (UTC)


 * What do you mean by, "and these pills cause night terrors"? Are you implying that certain medicines cause night terrors? μηδείς (talk) 23:25, 19 October 2014 (UTC)
 * The DSM implied it with their criterion that "the disturbance is not due to the effects of a substance". I'm just furthering the implication. Venlafaxine (Effexor) seems to play some terrifying tricks, if Google's any indication. Other SSRIs, too. A catch-all euphemism for the effect is "abnormal dreams". InedibleHulk (talk) 15:29, 21 October 2014 (UTC)

There are scientists who deny the existence of mental illness, see here:

"But now the DCP has transformed the debate about diagnosis by claiming that it is not only unscientific but unhelpful and unnecessary. "Strange though it may sound, you do not need a diagnosis to treat people with mental health problems," said Dr Lucy Johnstone, a consultant clinical psychologist who helped to draw up the DCP's statement.

"We are not denying that these people are very distressed and in need of help. However, there is no evidence that these experiences are best understood as illnesses with biological causes. On the contrary, there is now overwhelming evidence that people break down as a result of a complex mix of social and psychological circumstances – bereavement and loss, poverty and discrimination, trauma and abuse."" Count Iblis (talk) 18:08, 19 October 2014 (UTC)


 * Yes, there are also libertarians who claim mental illness is a government plot. Thomas Szasz. The fact that certain treatments are hit and miss hardly indicates the irreality of mental illness. Such things have been (1) known since antiquity and (2) can often be induced pharmacologically.  So long as we define mental illness as a dis-ease that has to do with the mind, I am not sure what denying its existence accomplishes. μηδείς (talk) 23:55, 19 October 2014 (UTC)


 * DCP=Division of Clinical Psychology the largest division of the British Psychological Society. See also Psychiatry Richard-of-Earth (talk) 19:27, 19 October 2014 (UTC)


 * Better if the OP asked: is whatever causes anxiety causing all mental disorders? It would be a bit of a Holy Grail of the mental heath field to find a single source for all mental disorders. Sigmund Freud and anyone else who cares to guess at the structure of the mind will say it is a breakdown or inherent dysfunction in the structure that is the basic cause of insanity. I have heard such people referred to as "Structuralists", but of course clear terminology is hard to come by in a field where nobody seems to understand what they are studying. Structuralism (psychology) is a particular theory of consciousness and Personality psychology seems to be the area of study of mind structure independent of neurological structure and more broadly Mentalism (psychology). The more common approach ignores structure (biological, mental or otherwise) and just catalogs behavior, give names to conditions and from past experience (read trial and error) suggest best treatments. This is called behaviorism and it is how the field of medicine has worked in the past. Except in modern medicine medical diagnosis is done with biological tests and not just observation of symptoms. A common complaint I have heard is "I saw the psychiatrist, we talked for 15 minutes, he made a diagnosis and gave me a drug prescription". But to be fair if they find a way to do a biological test for a condition, it is no longer a psychological condition, but a neurological one.
 * But I suppose you could just sum it all up and say: isn't it all in your mind anyways? Richard-of-Earth (talk) 19:15, 19 October 2014 (UTC)
 * It's always Coca-Cola, in conjuction with Coca-Cola advertising. InedibleHulk (talk) 19:22, 19 October 2014 (UTC)
 * Seriously, though. InedibleHulk (talk) 19:28, 19 October 2014 (UTC)


 * There are doctors who have likewise denied the existence of allergies. And there are many (hopefully not doctors) who believe the earth is flat. ←Baseball Bugs What's up, Doc? carrots→ 11:27, 20 October 2014 (UTC)


 * It's not so much denying the phenomena exists, rather that they will say it's normal physiology and the fact that the patient suffers is because of secondary effects like anxiety. E.g. you could lead a normal life if you hear voices and let that go untreated. However, if everyone is told that this is not normal then that alone would make the persons who start to hear voices feel extremely uncomfortable. Count Iblis (talk) 22:29, 20 October 2014 (UTC)


 * I have heard voices when sick or sleep deprived, and knew I was hearing voices. The problem is that schizophrenics (and I knew a friend and a college roommate who developed schizophrenia in their 20's), don't have the rational capacity to tell that they are sick and the voices are false--and they don't trust you if you tell them otherwise.  Luckily both those people can function on medication, but they are not the same vibrant humans they used to be. μηδείς (talk) 19:11, 23 October 2014 (UTC)
 * They're not sure (too sure, rather) while they're psychotic, but can be as rational as the next person about it when they're not. A fair bit of the vibrancy comes back after a few months of adjusting to the meds. Not quite the same person, but that's sometimes a good thing and sort of the point. Of course, schizophrenics are various people. Your experience should vary. InedibleHulk (talk) 19:42, 23 October 2014 (UTC)


 * Some mental disorders are actually characterized by pathologically low levels of anxiety, in particular the manic phase of bipolar disorder, and psychopathy. Looie496 (talk) 13:58, 20 October 2014 (UTC)
 * Parts of Psychotherapy will always claim cures for anything, as long as the "therapists" get payed for treating it. This is the same phenomena as in parts of Medicine and Pharmacy which promises you miracle cures (like healing homosexuality) and sells you anything (like Baculum) as long as someone believes in some healing effect. --Kharon (talk) 09:45, 21 October 2014 (UTC)

"Offset bandages" ?
1) Do bandages exist with a (presumably plastic) ring built in to offset the bandage from a small wound, to prevent it from sticking to the wound ?

2) If so, what are they called ?

3) Do we have an article on them ? StuRat (talk) 17:01, 19 October 2014 (UTC)


 * 1) They make them for corns and calluses. Here is a site about them. They are made of foam.


 * 2) No special name. Rings or pads.


 * 3) Not that I can find, beyond a passing mention at Callus. Richard-of-Earth (talk) 17:20, 19 October 2014 (UTC)


 * That's a good start, but seems to be self-adhesive foam or felt rings, while I had non-adhesive rings attached to an adhesive bandage in mind. I suppose those rings could be used in conjunction with a bandage, to keep germs off the wound.  If they made self-adhesive rings with a piece of fabric covering the top of the opening, that would be even better. StuRat (talk) 18:14, 19 October 2014 (UTC)


 * Consult your First Aid guide as to whether it's better to aerate a wound or to keep it covered with something. ←Baseball Bugs What's up, Doc? carrots→ 19:00, 19 October 2014 (UTC)


 * The method I described should do both. That is, bacteria would be kept out, and yet there would be a small air gap (hopefully antibiotics and the immune system could deal with the tiny amount of bacteria sealed in the air gap).  StuRat (talk) 19:58, 19 October 2014 (UTC)


 * According to our article Adhesive bandage, "Some bandages have a thin, porous-polymer coating over the pad to keep it from sticking to the wound." In my experience, such bandages don't work as well as one would like in the "keep it from sticking to the wound" department, but they do work better than uncovered gauze pads. I don't really see how your "ring" idea would work; if the space between the bandage and the skin were fairly great, the bandage wouldn't be effective, and if it were small, the space would fill with blood and the fibers of the bandage would still get trapped in the clotted blood, causing stickage. Deor (talk) 21:04, 19 October 2014 (UTC)


 * I'm assuming the bleeding will have stopped, or almost stopped, by the time the bandage is applied. StuRat (talk) 23:29, 19 October 2014 (UTC)


 * Disclaimer: Every case is different. This is strictly personal experience and may not apply to you: Some time back I had a small sun-damage lesion removed, and I was advised to coat the area with Vaseline to keep it moist, rather than exposing it to the dry air. But you should consult your physician about current thinking on treatment of small wounds. ←Baseball Bugs What's up, Doc? carrots→ 21:20, 19 October 2014 (UTC)

Why don't good bacteria become resistant to antibiotics?
Why don't good bacteria become resistant to antibiotics? — Preceding unsigned comment added by 111.10.167.210 (talk) 19:53, 19 October 2014 (UTC) ==


 * Who says they don't? --Stephan Schulz (talk) 20:06, 19 October 2014 (UTC)


 * Why don't non-oppressed people become resistant to oppressors? They aren't attacked. Same with "good" bacteria. No action, no reaction. Doesn't mean it's impossible to rile them up. But as long as they're with us, they have no reason to go against us. InedibleHulk (talk) 20:29, 19 October 2014 (UTC)


 * I disagree. Human bodies (and livestock) have both good and bad bacteria in them, and when we use antibiotics, they target both, so both should become resistant. StuRat (talk) 20:45, 19 October 2014 (UTC)
 * Semantics, I guess, but I'd go with "immune" for the good guys. They're not really part of the struggle, so nothing to resist, just to ride out. They've usually had plenty of time to settle in, both in a particular body and humans in general, by the time we decide to poison the troublesome foreigners. And when that war is won, life goes back to normal. Normal for the bad guys is either killing or being killed, they don't have time to assimilate into a productive system. InedibleHulk (talk) 21:22, 19 October 2014 (UTC)
 * To make it maybe a bit clearer, imagine a town of ten thousand good people. When a hundred bad people show up and the mayor demands indiscriminate bombing, the odds are great that all the bad guys die about the time a hundredth of the good guys do. The only way the bad guys can survive to breed is being a special sort of mutant, while the good guys can either be special or just patient. After enough rounds, the dark side will have far more mutants, proportionally, and continually better chances of passing on the power to the kids. The good guys have all the time between battles to have ever more normal kids, who peacefully work on the gut farm, possibly never even meeting one of their own mutants. It'd be different if enough of us took antibiotics every day of our lives. InedibleHulk (talk) 22:10, 19 October 2014 (UTC)


 * Yes. they probably do, but we only notice harmful antibiotic resistant bacteria. If anyone would care to do a study, they could probably find some helpful antibiotic resistant bacteria.  It would be good to know about them, as the right kind could be quite useful, say gut flora bacteria to replace those wiped out by a course of antibiotics. StuRat (talk) 20:33, 19 October 2014 (UTC)


 * One of the most common side effects of taking antibiotics is diarrhea. This implies good gut flora that would normally aid in the digestion of otherwise undigestible sugars, etc., have been affected. μηδείς (talk) 23:14, 19 October 2014 (UTC)


 * They do, though you need to keep in mind that, when it comes to beneficial bacteria, it all comes down to location, location, location. In the lower portion of your digestive tract, Bacteroides fragilis is a friendly bug, but if it gets into your bloodstream, say, you'll get sick. Other members of your gut flora, such as E. coli are similar in that regard. Matt Deres (talk) 01:07, 20 October 2014 (UTC)

Massive shooting star
I just saw the largest shooting star I've been privileged to witness. It took place around an hour ago in the south of England. Is there a resource or an organisation I can use or talk to in order to determine that I didn't just hallucinate? P.S. This is not a medical question. The Rambling Man (talk) 20:32, 19 October 2014 (UTC)
 * Not official by any means, but the UK Meteor Network seem to be chirping about a fireball over central and southern England this evening. –  Juliancolton  &#124; Talk 20:47, 19 October 2014 (UTC)
 * Thank you, perfect answer. Despite it not being a medical question, it still made the hairs on my arms stand up...!  The Rambling Man (talk) 21:28, 19 October 2014 (UTC)
 * Probably an Orionid .  Acroterion   (talk)   21:29, 19 October 2014 (UTC)
 * Thanks Acroterion. The Rambling Man (talk) 21:39, 19 October 2014 (UTC)


 * When one witnesses something like this it is hard to estimate the number of seconds that it was visible -due to the surprise. Hazard a guess. For how long was it visible to you? Your observation may help to narrow down the origin. Which direction was it traveling? (ie. Northwest to Southeast etc). Was it monochromatic white or did you see greens too? --Aspro (talk) 22:03, 19 October 2014 (UTC)
 * My guess after a quick reading the other reports. It was a low orbital satellite re-entering not a shooting star.--Aspro (talk) 22:21, 19 October 2014 (UTC)


 * Why, User:Aspro, do you ask about greens? I saw a green fireball in the 1990's moving east-to-west just before sunset. μηδείς (talk) 23:16, 19 October 2014 (UTC)


 * Neat. I wonder if infalling satellites work like a flame test in the lab.  Maybe it was made out of copper ... niobium ... vanadium ... something.  (I wouldn't guess what elements are most common for building satellites) Wnt (talk) 23:23, 20 October 2014 (UTC)


 * My father and I saw it as we were driving south along the NJ turnpike around 6-7pm-ish from NYC to the Philly area. The sun had only just set, and what we assumed was a meteor was a bright, apparently monochromatic green.  I assumed from User:Aspro's comment there must be a chemical reason. μηδείς (talk) 23:44, 20 October 2014 (UTC)
 * The meteor article mentions that metoroids containing magnesium produce green meteors. Meteors get different colors depending on the composition of the meteoroid and the composition of the atmosphere which varies by altitude. 88.112.50.121 (talk) 10:04, 21 October 2014 (UTC)
 * I will link 88.112.50.121 & μηδείς together here. The colour could be the result of more than one reason. This is why reports are important. Monochromatic green (rather than "or did you see greens too?" {as per my previous quote} meaning it was it not monochomatic) could also be due to ionization of the atmosphere.  So the  report of a Monochromatic Green suggest to me (without any reference) that in this instance, this was not a chemical effect but that simply that of altitude rather than composition (see:  |Auroras and the atmosphere). At lower altitudes were rapid oxidation (combustion) can take place, and the elements will emit their bright and visible caricaturist spectrum. Will leave it to the two of you to decide, who was right right and who was wrong but I think it was a draw.--Aspro (talk) 19:42, 21 October 2014 (UTC)

I saw it too! (from the M25 motorway north of London) I had rather convinced myself that it must have been a firework, as Bonfire Night is approaching. Alansplodge (talk) 11:03, 21 October 2014 (UTC)


 * Thanks for your comments:
 * As Wnt questioned. It is a bit like a lab flame test. This is why, if you should see an awesome sight sight, one should switch mode and go into unemotional observation mode. In this mode one can mentally record what one's senses is actual observing, rather that get distracted by what one emotions are tell you your seeing. For instance, (and following on from the other above comments) artificial satellites are constructed from many different alloys. Some (like the aluminium frame) melt at low temperatures and being lighter will slow down faster that say an ion flux sensor made out of a lump of iron. Some sat's have lithium batteries...  etc,. etc. It only take a sand size pies of comic dust to leave a less than a second streak called a shooting star. Yet an artificial satellite has kilos of copper conductors.  Because of the different masses and melting points  and masses of  materials  on de-obiting artificial satellite,  they  will tend to spread out along it trail and leave sparkles of different colours. This is more distinct to the human eye – as cameras are less sensitive.  Second:  Compass Direction. Most natural meteors enter our atmosphere on the ecliptic plane. Those that don't are probable from outside our  solar system. So their path over the observer is important in narrowing down the possible origin. Third: Most shooting stars have a high relative velocity to that of the Earth. Hence, the appear and go in an instance.  Orbital satellites re-entering, tend transverse the sky for longer.  I did not want to spell all this out before hand until observations were in because spelling it out can lead to reporting False memory. I.e.,  reporting what they have been lead to think that have witnessed, rather than reporting what their eyes actual saw.  A crowdsource of unadulterated eyewitness report could provide much useful information.Finally: It could have been an Orionid but this is where multiple reports can help to establish if the temporal event was probable  coincidence. We will never know for sure unless we find a bit of it on Earth.--Aspro (talk) 18:51, 21 October 2014 (UTC)


 * It was almost certainly an Orionid, not a satellite or anything else. There was no colour in my observation, it lasted approximately two to three seconds, it was bright white and left a trail. From my position it moved from left to right looking approximately East.  The Rambling Man (talk) 19:02, 21 October 2014 (UTC)


 * Thank-you. That is three useful observations. (1) Two to three seconds. (2) Left to right looking east (so one can assume it was going north to south). (3) Monochromatic. We might never know without doubt what  this fireball was but we can look for weakness in eye testimonies. Would you be gratuitous enough to be the guinea pig to show the value of  cross examining eye witness reports. Not that I doubt your testimony to be true but  just incase something has been missed that throws new light on understanding off  what you most probably  witnessed?    Be reassured,  other editors here will drop  on me like a ton of hot brick if I err . So here goes...  Question: what exactly were you doing in the hour before you saw this phenomena (to use a neutral term) ? Don't worry if you happened to have spent all afternoon in the pub drinking alcohol because the other editors will jump on me an nullify my response if I err. Simple asking: what where you doing in the last hour before you looked up! Then we can ask μηδείς what she was doing in the last hour and there 'might' just be some little but important difference that goes on to  illuminate. I go to to this effort to get across the point that one should mental record and preferably  writes down immediately everything! Anyway, that’s enough waffle out of me and over to you. --Aspro (talk) 20:46, 21 October 2014 (UTC)
 * r u sure thatll work if both parties can see i mean-  ~Helicopter  Llama~  20:55, 21 October 2014 (UTC)


 * Sure? The only thing I am sure about is death and taxes. Even then, if medical science could suddenly give me eternal life, I will eventual  become rich enough, to afford financial advisers who can ensure  that I don't have to  pay any taxes at all  (save for a cent here or there perhaps). --Aspro (talk) 22:41, 21 October 2014 (UTC)

Chemistry - Dual Supercritical CO2 extraction?
Long-Chain Omega-3 FA's are extracted from Algae mainly by the the famous solvent Hexane. I don't know why but there is some criticism about this, and some manufactures started using other methods for extraction (It seems weird for me not to grind the Algae with some plant-based oil but that's for another discussion). Anyways, in this Vegan, Algae-based Omega-3 supplement ("Garden of Life - Minami VeganDHA Omega 3 Fish Oil, 60 Softgels", Available at Amazon for example), the manufacturer says it uses "Dual Supercritical CO2 extraction". Could someone please elaborate, in simple words what is this process and why is it allegedly safer than "Harsh solvents" (As said on the back of the package), such as Hexane (I guess), and others?

Thank you. Ben-Natan (talk) 22:11, 19 October 2014 (UTC)


 * If you compress carbon dioxide enough it becomes a supercritical fluid, with properties of a liquid and a gas. Generally speaking it is about as dense as the liquid form (roughly) but less viscous (I think).  Because carbon dioxide is O = C = O, a linear molecule, it is effectively apolar, with no particular direction having most of the positive or negative charge.  That makes it functionally much like hexane, which is H3C - CH2 - CH2 - CH2 - CH2 - CH3, also linear and therefore symmetrical about a central point.  But when a product extracted with carbon dioxide is exposed to normal air, obviously, the liquid CO2 has to go away and come into equilibrium with the normal air.  Whereas hexane might stick around and might have some health or at least flavor effects.  Hexane is not tremendously terrible as organic solvents go, but it isn't really something encountered much in a natural diet.  (See also Hexane-2,5-dione, though of course here we're talking about miniscule amounts)  Oh, and the reason not to use vegetable oil is you'd be stuck with the vegetable oil afterward because (obviously) it doesn't evaporate.  Whatever you use the omega-3 for it probably wouldn't sell as much with a heavy content of other fats. Wnt (talk) 22:16, 19 October 2014 (UTC)


 * Wnt, Thank you for this detailed, and generous answer, You helped me very much!, I just have one little question to see I understand you properly: Is Molecular Apolarity differs from Covalent Apolarity? (The Covalent bonds at the formula above seems Polar to me, i.e from different elements, and yet you titled the molecule itself as Apolar). Ben-Natan (talk) 23:17, 19 October 2014 (UTC)


 * See chemical polarity. Usually the polarity of the molecule is most important.  However, there are other factors that can be important, that I really don't understand well - for example, isolated mercury atoms and hexane are both nonpolar molecules, but they would not freely mix if put together.  In general, if you look up the solubility of a compound, you won't find one number that you can deduce the behavior of every solvent from.  Instead, you find empirical observations of how it does in various solvents.  Usually you can make a good guess what the behavior in one will be from another, but apparently it isn't mathematically reliable. Wnt (talk) 04:28, 20 October 2014 (UTC)
 * Our two most-relevant articles to the original question about the process are Supercritical carbon dioxide and Supercritical fluid extraction (though especially the second one seems more technical than we need here). Just for interest, here's a lead ref I found regarding solubility (experimental values and discussion of origins of them) of mercury metal in various solvents: DMacks (talk) 05:02, 20 October 2014 (UTC)