Wikipedia:Reference desk/Archives/Science/2008 January 20

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January 20[edit]

Can you name any of these tropical flowers?[edit]

One for the botanists among us! I spent some time taking pictures at an indoor rainforest centre today and shot quite a few flowers, but I didn't have a notepad and pen with which to note the plant names — I'm usually more organised than that. I would like to be able to identify them so that I can add captions to my photo gallery at [1] If anyone can identify any or all of these plants and post the names of any that you know, that would be really wonderful! Thanks! Adrian M. H. 01:06, 20 January 2008 (UTC)

Hi Adrian, nice pics. No identity for 1 which is 2 as well, and 3 appears to be the coloured bracts of it with the flowers spent; 4 is a variety of Phalaenopsis orchid; #5 & 6 is like a Strelitzia aka "Bird of Paradise" plant; 7, looks like the aerial roots of a climbing Philodendron, ie, a climbing variety of "Elephant ear" plant – see also Caladium (or a red-stemmed Colocasia but this one doesn't seem to be the climbing type); 8, likely Red Ginger; 10 & 11 is an Anthurium, a red lily endemic to Central and South America; 12 is a doubled variety of Hibiscus. Cheers, Julia Rossi (talk) 08:25, 20 January 2008 (UTC)
Wow, thanks for the info, Julia. That's excellent and very helpful! I'll check those links. And thanks for the complement as well; I'm glad you like them! Adrian M. H. 12:56, 20 January 2008 (UTC)
For the record, #7 is Thunbergia mysorensis a vine from southern India, atractive to hummingbirds and the rest is on your talk page.: ) Julia Rossi (talk) 10:56, 21 January 2008 (UTC) PS Sorry, it looks like I transferred this answer to your talk page when I was really trying to keep it short. Now there's only the plant in the first three to discover. Cheers, Julia Rossi (talk) 03:05, 22 January 2008 (UTC)

solar energy per square centimeter per magnifying power[edit]

I apologize for disturbing you. I am trying to figure out the power that is generated by magnifying lenses. You site burning lenses 50mm that the Viking had that were used starting fires. For a given magnifying power what is the joules per square centimeter that is produced. what are the limits of magnifying lenses in converting solar energy? I am trying to create something I call a sun rectifier. For example using mirrors to focus more sunlight on a magnifying lens is more energy produced. Can you augment the photons with electrons that are added by a wind turbine. Sincerely Yours Veronica Skov —Preceding unsigned comment added by (talk) 01:19, 20 January 2008 (UTC)

First of all, please don't apologize for asking a question. That's what we're here for!
At high noon on a sunny day, the insolation of Earth's surface is about 1000 watts per square meter. (In other conditions, like cloudy weather or morning/evening, it is less.) The power per area in the spot produced by a magnifying lens is going to be increased by the ratio between the area of the lens itself and the area of the spot. For example, if the lens is 50 mm in diameter and the spot is 2 mm in diameter, the power/area of the spot is increased by a factor of , so the maximum power/area is about 625,000 watts per square meter, or 62.5 watts per square centimeter. Note that an answer in joules per square centimeter wouldn't make sense, because the energy in joules depends on how long you allow the heat to built up. If you wait twice as long, you'll get twice as much energy. That's why I gave my answers in watts per square centimeter, because a watt equals one joule per second. —Keenan Pepper 03:01, 20 January 2008 (UTC)
Good answer, Keenan. --Taraborn (talk) 10:21, 20 January 2008 (UTC)
Ignoring the small losses in the optical apparatus which concentrates the sunlight, with 625 watts per square centimeter, then the Joules delivered per square centimeter is just 625 times the number of seconds, since a watt is one joule per second. Edison (talk) 20:12, 20 January 2008 (UTC)

'Bibliography trees' etc.[edit]

Hello. Let's say you have a scientific work (paper/book) on a subject, and you write out the list of references, i.e., the bibliography. Then, you take the 1st ref's bibliography and write it out, too, etc. In other words, you make a treewalk (or tree traversal) on the references. I have three question complexes on that:

  1. Is there a term for such a treewalk? Is there a term for the result? Are there people doing such things? Where can I read about it?
  2. Without doubt, at some depth of the treewalk you get to read works that are so old that they don't have their references neatly arranged in bibliographies but where they are loosely mentioned in the text, or in footnotes, at best. So, the actual data has to be extracted and, probably, completed. Is there a term for the result? Are there people doing such things? Where can I read about it?
  3. In general, it might be nice to have bibliographies of specific scientific works as computer readable files. I have found only websites that collect such bibiographies on the topic of computer science. Where can such sites be found on other topics?

Many thanks in advance for any hints. --Rwst (talk) 09:53, 20 January 2008 (UTC)

PubMed can provide access to a large number of references that have been cited in biomedical research articles. --Memenen (talk) 16:19, 20 January 2008 (UTC)
The Web of Science and ISI Web of Knowledge by Thomson Scientific are citation databases which contains such a "Web". They not only have backwards links (this paper cites this older one) but also "forward" links (this paper is cited by these more recent papers). It is possible to download all the papers cited (or that cite) a particular paper in electronic format. (Note that Thomson is the company behind the reference management software pacages EndNote and Reference Manager.) I believe the database is manually curated, and only goes back so far (1950s-70s or so). Unfortunately, it is a commercial product, and accessing it requires a paid subscription. (Although many universities have site licenses.) -- (talk) 22:23, 21 January 2008 (UTC)

Tunguska event[edit]

How did the witness Stepan Ivanovich see an area of flattened forest before he saw the flash of an explosion? It seems he was describing a second explosion. He states that there were many flashes and thunderings in differant locations. And other statements would tend to agree. Many statements mention the sounds of multiple explosions. Stepan Ivanovich, said: Suddenly, above the mountain, where the forest had already fallen, something started to shine intensely, and, I tell you, it was as if a second sun had appeared; the Russians would have said “something suddenly flashed unexpectedly”; it hurt my eyes, and I even closed them. It resembled that which the Russians call lightning. And immediately there were, loud thunder. That was the second thunderclap. ( see ) ((User Nosut)) 10:30, 20/1/08 (UTC)

First, witness records are not always reliable. In this case, the witness was apparently interviewed 18 years after the event! And even if the primary witness is reliable, the reporters and the translator all may introduce errors and bias. Secondly, taking the reports at their face value, their may have been multiple comet fragments hitting over a period of time. Smaller ones will completely dissolve in a fireball. See Meteoroid. A famous example is the recent collision of comet Shoemaker-Levy 9 with Jupiter.--Stephan Schulz (talk) 11:12, 20 January 2008 (UTC)

Black Widow spider[edit]

Hello, I'd like to know if the Black Widow spider and the North American scorpion prey one on the other. I tried looking it up on the Black Widow article page but I couldn't find anything regarding this. (talk) 12:07, 20 January 2008 (UTC)

I doubt it—their habitats are quite different and it's hard to imagine them coming into contact with one another. -- (talk) 17:21, 20 January 2008 (UTC)

Correction Fluid[edit]

Hello. If I apply correction fluid to blank 5 mm of text under normal circumstances, then how much correction fluid do I need to blank 8.5 m of text? I am deciding whether a 22 mL bottle of correction fluid blanks as much text as an 8.5 m correction tape. Thanks in advance. --Mayfare (talk) 16:22, 20 January 2008 (UTC)

I have wondered about the same question, but there isn't a simple answer because correction fluid can be applied at different widths and in different thicknesses. I find it useful to have both available because the fluid can be used for very delicate correction if it has a fine brush, whereas the tape is quicker for a long line if the width matches. There is waste in both systems, and I think best value will depend on how you use them (and also where you buy them because prices vary surprisingly in the UK and probably elsewhere too). dbfirs 16:45, 20 January 2008 (UTC)
Get one of those white-out mice by tipp-ex ( That should make it a little easier to calculate how much you need as they apply it in a bit more of a 'reliable' manner. It's £2.37 and contains about 9m apparently (with a width of 4.2mm). So to do 8.5m you'd need... 1 but i'd say 2 would be needed in reality just because of waste. ny156uk (talk) 18:19, 20 January 2008 (UTC)
I suggest convincing this guy to measure it. – b_jonas 10:33, 22 January 2008 (UTC)

Virus vs opium poppies[edit]

Has there ever been a genetically engineered or tailored virus/fungus/bacteria that's been directed against opium poppies (as opposed to the usual toxic herbicides and chemicals)? If this was done, would it be successful in fighting poppy crops in places like Afghanistan and South America, and can it be safely done? (talk) 17:17, 20 January 2008 (UTC)

Has there been—no. Would it be successful—depends. The problem with opium cultivation is not a technical one so much as it is an economic and political one. In order to destroy poppies in South America, for example, you need cooperation of local governments, many of whom have long been either in fear of or indebted to the cartels which profit off of such crops. In Afghanistan opium poppies make up a large part of the native economy. It would be diplomatically problematic to try and carpet bomb a country with genetically altered herbicide against their will, and when there's a strong economic incentive to find a way around a difficulty, it is usually found (and these need not include technical fixes as well—just bribe the pilot to "accidentally" miss your crop and report it as hit). -- (talk) 17:29, 20 January 2008 (UTC)

Well you're talking about targeted strikes using herbicides, while plant diseases might be released (maybe covertly to try to avoid a lot of this political stuff), spread through say bees/insects/birds/water/vectors and then contaminate and multiply with minimal effort (depending on the robustness of the organism or virus). You just let it infect, divide, and multiply. Or is it more to it than that? (talk) 17:44, 20 January 2008 (UTC)

To my knowledge there is no genetically modified virus that acts in this manner. The main obstacle would be to ensure that it attacks only Opium and not beneficial plants living nearby. Water is almost certainly far too risky/controversial/infeasible to use as a vector. Most water used for Opium cultivation is taken from private wells, and the virus would not evaporate to spread to other fields. Birds have little interaction with Poppy seeds until they eat them for sustenance in the wintertime. Not the best vector. Insects/Bees used to pollinate poppies would be an interesting vector, but would take a long time to/never would spread to other hives and crops.

I think herbicide would be the best option here, unless you could create a virus with a long incubation rate and an alarming rate of transfer.

Interesting concept, though. --.ιΙ Inhuman14 Ιι. 19:33, 20 January 2008 (UTC)

A warning tale is the one of Roundup-ready cocaine. [2] In short, the US supported the wide-spread use of Monsanto's herbicide Roundup against coca plantations in Colombia. Of course, in the great tradition of the American Luftwaffe, they hit plenty of non-coca plantations as well. A resistant coca-strain developed or was developed very soon, and, with the herbicide keeping traditional crops down, even more coca was grown.
But even if we could eliminate poppy plants (also used for other things than opium, of course), there is a moral dimension. There is nothing harmful about growing Opium at all - indeed, it has a number of beneficial medical uses. What is harmful is the misuse. But it's not as if Afghan peasants force Western consumption (as e.g. in the Opium Wars of yore). By what rights do we destroy their cash crops? Finally, its very hard to predict what effect the elimination of a whole species will have on the ecosystem. --Stephan Schulz (talk) 13:35, 21 January 2008 (UTC)

Having a poppy-killing virus would be dangerous for certain legitimate economic segments - the opium poppy is the same species as the poppy seed poppy. Uncontrolled release of a virus effective enough to control opium production would likely result in the elimination of poppy seed muffins and bagels, as well as opium/heroin. Geographical separation wouldn't really help, as agricultural diseases show a remarkable tendency to spread, and an annoying persistence to elimination. -- (talk) 22:10, 21 January 2008 (UTC)

Lack of spatial awareness[edit]

It appears to me that there is an increasing lack of spatial awareness amongst people. The sort of thing that I mean includes blocking supermarket aisles with trolleys whilst looking at goods, standing so as to block entrances and exits (the fools who stand on the kerb right in front of the bus door while people are trying to get off really get my goat), that sort of thing. So, my questions are 1) have others noticed this, and 2) what could be the explanation of this? DuncanHill (talk) 17:52, 20 January 2008 (UTC)

How long have you been sampling for? Assuming that it is on the increase, perhaps it correlates with a decrease in consideration? ----Seans Potato Business 19:10, 20 January 2008 (UTC)
I'd say it's become noticeable over the last 5 years (ish). I have considered a decline in consideration, but the looks of utter incomprehension in the faces of people when it is pointed out to them that people can't get off a bus when they are blocking the door suggests to me it is an inability to judge spatial relationships. Good point though. DuncanHill (talk) 19:38, 20 January 2008 (UTC)
If spatial awareness were the problem, surely people would make other errors (trying to push trollies through spaces too small for them, crashing trollies into people, obstacles, and other trollies; and the bus people would fall over when they missed the step, or bash their heads on the poles when trying to stand up). I don't see that myself. Sean's "jerk" hypothesis is tempting, but it's fundamentally a claim that people these days are worse that their counterparts in the past - a claim that's been made forever, one that really can't (in general at least) possibly be true (if it were, we'd all be degraded morlocks by now). You can't, on the other hand, discount observer bias - in particular, you may be suffering from early-onset Meldrew syndrome (if you were tempted to disagree with my morlocks statement above, then it's probably quite advanced). -- Finlay McWalter | Talk 22:36, 20 January 2008 (UTC)
I blame the Kaiser, it's all been downhill since 1914. DuncanHill (talk) 23:06, 20 January 2008 (UTC)
Perhaps this is all a result of an increasing population density in your area? The more people out and about the more likely you are for this to occur. Additionally perhaps in part it is also a change in mood for yourself? Say before shopping/bus journeys were less 'stressful' so you were more likely to not 'notice' the blockages etc. I say all of this purely because every single generation (virtually without fail) says that the generation coming through after them is worse/less respectful/etc. etc. Not to suggest you're old/this is about young people, but I could imagine it's a similar 'process' whereby you have a more rose-tinted view of the past than it really is, and similarly you have a more depressive/cynical view of the current day. Certainly without some research it would be hard to say whether there has been any real change, or just perceived change. ny156uk (talk) 20:03, 20 January 2008 (UTC)
If anything I'd say it is commoner in people my age and above! Children seem to have a natural sense of space. DuncanHill (talk) 21:49, 20 January 2008 (UTC)
Its called acting like a complete asshole/dick with no respect for other people and being totally selfish to boot!(Also applies to driving manners)--TreeSmiler (talk) 00:55, 21 January 2008 (UTC)
I'm one of those idiots (sarcasm alert) that value keeping left on escalators and stairs, and generally keeping conscious of my location and whether or not I'm blocking anybody. This is of course a city-slicker thing. But one thing that suprisiess me is that the Asian people I encounter have no special affinity for this (based on the idea that in ultra-crowded urban Asian cities like Tokyo people from there would be more conscious of that sort of thing), that's not to necessarily say that Asians are (anecdotally of course) the biggest violaters of keep-left courtesy, but I definitely have not observed the opposite, i.e. that Asians are the most likely to keep left and not get in the way when you're trying to get past. So ultimately, in the part of Australia where I am, in multicultural areas, I wouldn't say the situation has reached epidemic level, but people blocking an escalator has now become a common occurance. I would put it down to either naivety, or apathy, not necessarily stupidity (or bad spacial ability) Rfwoolf (talk) 01:45, 21 January 2008 (UTC)
I also want to report another relevant topic: The out-before-in policy on buses. Think about it: let's imagine philosophically you have this very crowded bus, that gets to its stop, with people trying to get on and people trying to get off: who has right of way? Should people get on first and crowd up the place even more and make it even more difficult to get off? Or conversely, should people get off, easing the space situation and allowing more people to get in? ... But of course, time and time again, hooligans force their way into buses with no concern to the fact that you might be trying to get off. This applies to not just buses, but cars, buildings, rooms, toilets/bathrooms, government departments, etc Rfwoolf (talk) 01:48, 21 January 2008 (UTC)
Obviously you let the people off first (as your mommy told you all those years ago) unless its a big bus with separate entrance and exit channels.--TreeSmiler (talk) 15:19, 21 January 2008 (UTC)
One time when I tried to yield to someone else entering a store, he remarked that bulkier people like me tend to be more courteous in that respect. (I don't recall his exact words.) I said, it's because we know we're in the way! Smaller people, it often seems, can't imagine that they could possibly create an obstruction by chatting with their friend and their two shopping carts in a narrow passage. – A pet peeve of mine is the folks who stand paralyzed before a double door, waiting for me (coming the other way) to open one of the two doors so they can use it. —Tamfang (talk) 08:33, 25 January 2008 (UTC)

Chinese cabbage?[edit]

I bought one of these and now I want to eat it. I can't search for recipes yet 'cause I don't know what it is. I bought it in the Netherlands and the label says it's a 'spitskool'. Some translations give 'Chinese cabbage' but that's a load of rollocks because there's something else in Dutch called a 'Chinese kool' which translates also as 'Chinese cabbage' and doesn't look like the pyramid that I want to eat. Thanks in advance. ----Seans Potato Business 19:07, 20 January 2008 (UTC)

Is that Chinese leaf? Or maybe Pak choi? Each of these are very tasty, the leaf I use in salads but i've seen it stir-fried (i think), also the pak-choi I stir-fry. No idea if that's a good use of them, just a case of that's what i did and tasted nice to me. ny156uk (talk) 19:17, 20 January 2008 (UTC)
It's sweetheart cabbage see [3]. DuncanHill (talk) 19:24, 20 January 2008 (UTC)
If you slice it into roughly 1x3 inch pieces and marinade it in a red pepper/ginger sauce, you get Chinese hot cabbage, though you'll want a better recipe than my rough guess. It's quite tasty, though. --.ιΙ Inhuman14 Ιι. 19:42, 20 January 2008 (UTC)
As a Chinese myself I must say I have never seen such thing... --antilivedT | C | G 23:38, 20 January 2008 (UTC)
Are they really, really big? Clarityfiend (talk) 04:19, 21 January 2008 (UTC)
My guess is that you'd be able to use it in any recipe that called for cabbage, red cabbage, savoy cabbage, napa cabbage, or bok choi - even collard greens or kale. If you visit those pages, you'll see that they are all actually varieties of the same few species: Brassica oleracea & Brassica rapa. Although the flavors are slightly different so the dishes may taste different, and the cooking time may vary slightly, it's highly unlikely you'll end up with something inedible. Besides, half the fun of cooking is experimenting. I'll also note that you don't even have to be in the same family to substitute. I've seen cookbooks where they interchange kohlrabi, turnips, and potatoes freely. Depending on recipe, you could even substitute carrots or parsnips for potatoes and have it turn out. -- (talk) 22:03, 21 January 2008 (UTC)
It looks sort of like a different variety of napa. More pointier than what I've seen. bibliomaniac15 22:05, 21 January 2008 (UTC)

Sex determination[edit]

After a war in which males are killed, nature ensures more boys than girls are born. How does it manage this feat? MrsBucket (talk) 20:00, 20 January 2008 (UTC)

[Citation Needed] —Preceding unsigned comment added by (talk) 20:55, 20 January 2008 (UTC)

Nature gets more abortions for prenatal girls than prenatal boys? —Preceding unsigned comment added by (talk) 21:22, 20 January 2008 (UTC)

[4] MrsBucket (talk) 21:33, 20 January 2008 (UTC)
What really happens is that the larger female population only exists for 1 generation. With the overlapping generations, the different is only significant and noticable for 20 too 30 years. 'Mother nature' does not do anything to benefit the species. The ratio of males to female babies is not affected in any way by the number of males that remain in the population. The population tends back to 50:50 by itself as the generations die off and are replaced with new generations that are born 50/50. ALso when you think about it, there being born more males than females does not even up the population. You now have the reverse problem because in general people mate with people of the same age. For it to help you would have to have extra baby boys so that they could grow up to mate with people the age of their mothers...--Dacium (talk) 23:18, 20 January 2008 (UTC)
here is a reference from the Journal of Heredity that disagrees with the conclusion of the ASA reference. I'd be curious to see what this reference says, but I don't have a subscription. --Allen (talk) 00:40, 21 January 2008 (UTC)
That reference is the same thing as the Google books reference you have right before (I have access, and checked). -- (talk) 02:15, 21 January 2008 (UTC)
Note that all of the above references are from pre-WWII hereditary science. They are not necessarily the best references, for a variety of historical reasons. -- (talk) 02:12, 21 January 2008 (UTC)
So the original premise is wrong? Nature does not adjust the sex ratio as a consequence of war? MrsBucket (talk) 06:11, 21 January 2008 (UTC)
No clue; I'm just pointing out that searching through biometrical literature from before the Second World War isn't likely to resolve it. You'd want to find something more recent to demonstrate the phenomena at all before searching for a good theory to explain it. -- (talk) 02:17, 22 January 2008 (UTC)

The basic determination of sex (how the XX and XY chromosomes from the male and female are segregated) is always completely random. (talk) 15:24, 23 January 2008 (UTC)

But bear in mind that there may be a difference in male sperm and female sperm. This kind of things is often quoted [5], I'm not quite sure how good the evidence is but it's definitely possible. I'm also pretty sure there is evidence the females body appears to have some influence on the chances of successful conception of male vs female sperm (and as others have mentioned, there could be a difference in spontaneous abortion rates). Having said that, I would say it's rather unlikely this operates on a population level since how the heck do either bodies know? If I'm not mistaken the population at birth isn't quite 50/50% and I don't think this is entirely because of sex selection in some cultures. Indeed I seem to recall once that female embryos seemed to survive better but (I think this was in the US) there is a higher male population at birth. This was in the same book but (it was a sociology book so perhaps not the best book for this sort of thing but anyway...) and it didn't even mention this apparent discrepency. So I never quite understood this at the time (was there really such a strong sex selection bias in the US? or some sort of biological basis for this?). But it does all indicate it's a bit of a fallicy to assume the sex ratio must be 50/50 at birth even without human intervention. It's definitely close but it may not be exact and not just for random reasons. Nil Einne (talk) 17:33, 23 January 2008 (UTC)

ιλεος εντερο[edit]

ιλεος —Preceding unsigned comment added by (talk) 20:49, 20 January 2008 (UTC)

Entero / Intestine? (EhJJ) 11:35, 21 January 2008 (UTC)

Entero, whole number? Language desk? Julia Rossi (talk) 10:00, 23 January 2008 (UTC)

passing a drug test[edit]

How can one permanantly detoxify their body to be clean for an "upcoming, random drug test"? (talk) 23:58, 20 January 2008 (UTC)Randy

Never taking illegal drugs is usually a good strategy, along with carrying a list of the medications (prescribed and over-the-counter) taken in the last few weeks. TenOfAllTrades(talk) 00:12, 21 January 2008 (UTC)
One generally cannot "permanantly detoxify their body" (and any product that claims that you can is a scam). Drugs are metabolized by the body and excreted according to the pharmacokinetics determined by individual's body chemistry and and the drug's biochemical properties. Being well hydrated might help a little, if excretion occurs via the kidneys, but mostly time is the necessary ingredient. Some drugs leave traces for several days or weeks... — Scientizzle 02:13, 22 January 2008 (UTC)
And some leave traces in your fingernails or hair, which can hang around for quite a while. --Carnildo (talk) 21:12, 22 January 2008 (UTC)