Wikipedia:Reference desk/Archives/Science/2009 June 24

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June 24

basements

what building has the most basements?

Well, I don't know for sure - but it's very likely to be one of the tallest buildings - you have to go down deep to anchor the thing - hence lots of basements. SteveBaker (talk) 01:05, 24 June 2009 (UTC)

Hard to say, but tall does not correlate with deep. The height of buildings in Manhattan is directly related to the availability of Manhattan schist at a conveniently shallow depth. However, Grand Central Station and its associated tracks would be a contender in area, if not in number of levels. Acroterion _(talk) 01:10, 24 June 2009 (UTC)

The car park under Bloomsbury Square in London goes down seven levels. I'd guess that any building with extensive car parking or mass transit underneath would have a large number of subterranean levels. Acroterion _(talk) 01:41, 24 June 2009 (UTC)

The Petronas Twin Towers in Kuala Lumpur have the deepest foundations of any building in the world, at 120 metres, with improved ground another 30 to 40 metres below that. The foundation barrettes support the concrete slab which holds the buildings. I cannot find how much of the depth is "basement" in any traditional sense. All attention seems to have gone to the above-ground section of the buildings. - KoolerStill (talk) 02:23, 24 June 2009 (UTC)

Those foundations are pilings or caissons, neither of which contain (or are able to contain) living space, as they depend on being surrounded by earth for their strength. Acroterion _(talk) 03:57, 24 June 2009 (UTC)

The winner may turn out to be some building hardened against nuclear attack. Like the Pentagon or Cheyenne Mountain. APL (talk) 02:35, 24 June 2009 (UTC)

Wouldn't that count more as a bunker rather than a series of basements? - KoolerStill (talk) 03:49, 24 June 2009 (UTC)

Bunkers tend to be single-level caves mined horizontally into the side of a mountain, as it's easier to haul waste that way and cheaper to stay on one level. Cheyenne Mountain and the MoD facilities at Corsham are examples of this type. The Pentagon doesn't have much of anything under it by all accounts because it's nearly at sea level already. Some of the most extensive basements I've encountered are associated with sports facilities like Madison Square Garden, which need extensive utility space. There's not a lot of point in going down very far under a building with habitable space, as it's hard to get in and out for any useful purpose, as well as dark, wet and expensive. Building codes also discourage it as it's hard to rescue people and fight fires in multi-level underground structures.

Some of the deepest underground spaces, apart from mines, are underground hydroelectric power plants, but they're not usually more than a couple of levels in all, just big cavernous rooms. For mines, see Western Deep Levels. Acroterion _(talk) 03:57, 24 June 2009 (UTC)

My guess would be some sort of military project, or possibly a lab for extremely hazardous materials. There are unclassified military buildings who's "basements" already go down alot farther than most comercial buildings. The nature of what goes on in those buildings is usually still classified though.Drew Smith What I've done 04:21, 24 June 2009 (UTC)

Another not-so-classified military option is a missile silo. They go down pretty far. While the central silo has no floors, there are many floors surrounding it. -- kainaw™ 12:35, 24 June 2009 (UTC)

The OP asked about basements, and we're just guessing around tallest buildings. It turns out the Petronas Towers have only 4 levels of underground parking, no more than many much smaller buildings.

This is not a basement, but is going to be very deep (and may be the trigger for the question). "Far below the Black Hills of South Dakota, crews are building the world's deepest underground science lab at a depth equivalent to more than six Empire State buildings — a place uniquely suited to scientists' quest for mysterious particles known as dark matter.[1] - KoolerStill (talk) 08:36, 25 June 2009 (UTC)

May I add that according to unofficial reports, the Kremlin has an entire underground city below it to protect against nuclear attack?

76.21.37.87 (talk) 05:01, 26 June 2009 (UTC)

Oil rigs and similar marine structures usually have legs that go down to the bottom of the sea. You can go in the legs, so they would be like extremely deep basements. 89.240.105.155 (talk) 20:15, 30 June 2009 (UTC)

Transformer

What is the difference between real & ideal transformer?

It seems to me to be a homework question. Still, I can tell you ideal transformers have their mutual coupling constant, k=1. Practically, its less than 1. Also, there is some core losses as well as leakage associated with a real transformer. 59.93.180.203 (talk) 06:00, 24 June 2009 (UTC)

Have you looked at the article transformer? Ideal ones don't have a size whereas for instance a real one that was big might have a sign saying 'danger of death' Dmcq (talk) 12:00, 24 June 2009 (UTC)

A real transformer transfers electrical energy from one circuit to another and an ideal transformer turns from a car in to a giant robot. Livewireo (talk) 13:52, 24 June 2009 (UTC)

Hey Livewireo -- that was very funny! LOL! 76.21.37.87 (talk) 05:03, 26 June 2009 (UTC)

This Image

I got this image: image. It shaws a lightened up road, and the caption says "Luminous traces of a truck convoy in the evening". Can anybody explain that? 59.93.180.203 (talk) 05:57, 24 June 2009 (UTC)

Yeah. In the evening or at night you need to open your camera shutter for a rather long time, so that enough light hits the film. During that time the trucks move a considerable distance, so each headlight leaves a ribbon of light on the film. That is what you are seeing. Think of it as an extreme case of the motion blur. --Dr Dima (talk) 06:06, 24 June 2009 (UTC)

And we do have a page for the Motion blur, of course :) --Dr Dima (talk) 06:11, 24 June 2009 (UTC)

That kind of photography has also been used for stars, with some pretty breath taking results.Drew Smith What I've done 06:27, 24 June 2009 (UTC)

There are even some star-streaks in the sky on the OP's image. DMacks (talk) 06:53, 24 June 2009 (UTC)

Astronomy Picture of the Day has plenty of examples of star-streaks. —Tamfang (talk) 04:03, 25 July 2009 (UTC)

Thanks, all that pretty much explains this.218.248.80.114 (talk) 07:58, 24 June 2009 (UTC)

By the way, the usual term for this sort of photograph is a time exposure. Usually anything longer than about a second is included in the term. --Anonymous, 22:30 UTC, June 24, 2009.

Increasing oxygen on Mars

Lets say we want to terraform Mars. What would be the best way to increase the amount of oxygen on Mars? ScienceApe (talk) 06:37, 24 June 2009 (UTC)

Take a gander at Terraforming of Mars#Building the atmosphere. Clarityfiend (talk) 07:15, 24 June 2009 (UTC)

Basically - there is oxygen locked up in the soil as iron oxides - and in CO2 in the air - and possibly in all of that mysteriously 'missing' water. The CO2 could be converted to oxygen relatively easily by dosing the atmosphere with green algae or something and letting photosynthesis do the rest. However, turning the CO2 in the atmosphere into oxygen would cause the planet to lose what little greenhouse effect it already has. What we really need (at least initially) is more CO2 to warm the place up. So this presents something of a problem. Anyway - the article Clarityfiend points to covers it nicely. SteveBaker (talk) 14:52, 24 June 2009 (UTC)

Yeah, getting the atmospheric pressure and temperature up to acceptable levels is likely to be the hard part. Once you've done that you can get the oxygen fairly easily, relatively speaking. --Tango (talk) 16:03, 24 June 2009 (UTC)

You also have the problem of keeping the atmosphere you do create around Mars since it does not have much of a magnetic field with help prevent the atmosphere from being eroded from solar pressure, or solar winds or somesuch. 65.121.141.34 (talk) 15:06, 24 June 2009 (UTC)

That's only a problem on a geological timescale, I believe (or, at least, timescales of a few hundred years). If you can get the atmosphere there in the first place, you should be able to top it up enough every few hundred years to prevent a problem. --Tango (talk) 16:03, 24 June 2009 (UTC)

Isn't terraforming on a timescale of a few hundred years? — DanielLC 14:55, 25 June 2009 (UTC)

Depends how you do it. You may well need a higher rate of atmosphere production in order to compensate for losses during the terraforming process, but the main problem with such losses isn't during the process but afterwards - you need to maintain the atmosphere. The methods of generating the atmosphere can be rather violent (bombarding the planet with asteroids, for example), so could not really be continued after the newly terraformed planet was populated. You would need other methods to maintain the pressure, and that is where the timescale becomes significant. --Tango (talk) 18:53, 25 June 2009 (UTC)

I thought we just had to somehow activate the mysterious alien machine!!!

But that took a whole 30 seconds to terraform Mars...and I'm not that patient. StuRat (talk) 00:52, 25 June 2009 (UTC)

What is this wood coloured Insect called?

I found this insect in bushes what is it called.yousaf465'

File:Unkown Insect.jpg

Looks like a Walking stick to me. -- Aeluwas (talk) 08:06, 24 June 2009 (UTC)

Incest? Must be native to alabama or west virginia...Drew Smith What I've done 08:11, 24 June 2009 (UTC)

You know, prejudice against Southern whites is still prejudice.

As you ought to know, there's only one safe target for bigoted jokes, and that's the French :-) --Trovatore (talk) 08:37, 24 June 2009 (UTC)

I think you'll find it's the Americans. Algebraist 11:51, 24 June 2009 (UTC)

I recall reading that a particular joke on the stupidity of (US of) Americans worked well in most parts of the world due to a general low opinion of Americans, and also worked well in America because Americans presumed it was about those of the "other" half of the US. --Polysylabic Pseudonym (talk) 13:21, 24 June 2009 (UTC)

I think this is a mantis, not a phasmid ("walking stick"). The grasping forelimbs are clearly visible in the upper image. --Dr Dima (talk) 08:45, 24 June 2009 (UTC)

Dr dima you jogged my memory. That is a female Archimantis monstrosa.Drew Smith What I've done 10:04, 24 June 2009 (UTC)

Was it a female ? Oh I already released it into wild. You may compare the size with that of petri dish.yousaf465'

Actually, looking at the petri dish (assuming it's standard sized) this is probbly the mostrosa's smaller cousin. Still, I think it is definitly female.Drew Smith What I've done 05:36, 25 June 2009 (UTC)

It's is a standard size petri .yousaf465' 16:25, 25 June 2009 (UTC)

Then it is most likely Archimantis latistyla.Drew Smith What I've done 06:50, 26 June 2009 (UTC)

Wikipedia talk:WikiProject Moon

The last response to a post on the moon project was aimed at a bot in 2008. Sometime in 2007 some guy answered himself, and before that is in the archives. ~~ R.T.G 09:51, 24 June 2009 (UTC)

And? We can't provide pyschological help any more than we can provide phyisical medical advice.Drew Smith What I've done 09:56, 24 June 2009 (UTC)

I'm sorry, what are you saying? Can you provide any information about the results of the Chang'e 1 mission? ~ R.T.G 12:20, 24 June 2009 (UTC)

The Chang'e 1 article appears to cover the mission outcome sufficiently to my eye. What, specifically, are you asking about? — Lomn 13:01, 24 June 2009 (UTC)

Ok. That does appear to be true. Do you have a reference question?

Incidentally, I'm not sure about this this. Is it appropriate to advertise the RefDesk on other parts of Wikipedia? I'm not sure that I've ever seen that done before.APL (talk) 12:51, 24 June 2009 (UTC)

Generally, that kind of un-asked-for advertising is frowned upon - it's off-topic for the article's talk page and that's "A Bad Thing". But if someone posts a question to an article-space talk page that relates to the subject matter of the article - rather than relating to the writing of the article itself - then it would not be inappropriate to quietly suggest that people might get a better and more timely answer by asking it here. SteveBaker (talk) 14:46, 24 June 2009 (UTC)

Um, I don't know what to say about recommending the refdesk to people. (it was a project page, no answers in two years, the moon) Myself particularly, I was hoping to clear up the results of the search for water on the Lunar ice article but I do suppose that contacting members of the project directly would produce good results (which I have done now). Please, if you can tell me how the Chang'e 1 results went in relation to the water search please do (especially with a reference for the Lunar ice article). ~ R.T.G 17:28, 24 June 2009 (UTC)

Ah, I see. In the absence of claims that Chang'e found ice (something I would expect to be big news), I would assume there were no findings of significance -- which should not be confused with proving a lack of ice. Various news stories on LCROSS discussing the uncertainty of lunar ice support this premise. — Lomn 17:47, 24 June 2009 (UTC)

I thought something like that as well but it would good if they reported it, even as inconclusive and we could just update the article. I can't just change it to say "they musn't have found any" but there seems to be nothing around about the details. ~ R.T.G 13:46, 25 June 2009 (UTC)

FWIW, I've tagged the project as {{inactive}}, as it obviously is at present. --Kurt Shaped Box (talk) 17:43, 24 June 2009 (UTC)

Do Genetically Modified Crops Have Larger Yields?

I am wondering if there is evidence of GM crops yielding larger harvests than non-GM. Unomi (talk) 10:52, 24 June 2009 (UTC)

They can, if they're genetically modified to produce higher yields. Or they can be GMed for some other purpose, such as pest resistance, in which case they would also probably have higher yields as they aren't constantly eaten. Other cases, for example most pure science GM projects, yield is not the purpose of the GM, so often have much lower yields/growth rates/etc.Aaadddaaammm (talk) 11:48, 24 June 2009 (UTC)

Can you point to sources affirming higher crop yield? GM crops are in wide circulation it seems? Unomi (talk) 12:42, 24 June 2009 (UTC)

Our article on genetically modified food contains some information on the distribution of GM crops in various parts of the world; for example, "In the US, by 2006 89% of the planted area of soybeans, 83% of cotton, and 61% maize were genetically modified varieties". Gandalf61 (talk) 12:50, 24 June 2009 (UTC)

Right, what is interesting is that there is no mention of benefits, I would assume that the point of GM crops would be yield improvements or other form of economic benefit, it is not clear from the article if such a benefit exists? Unomi (talk) 14:54, 24 June 2009 (UTC)

A quick Google survey finds a couple theories. One is that GM crops fare poorly in the US. Another is that GM crops boost yield in India. The latter suggests that GM crops show an advantage in areas where pest control is less prevalent. US farms might see a GM benefit by foregoing pest control at the expense of yield -- depending on the numbers, this may be desirable environmentally and/or economically. I haven't searched for firm info along these lines, though. — Lomn 15:03, 24 June 2009 (UTC)

Thank you for those sources. Unomi (talk) 04:51, 26 June 2009 (UTC)

Apparently GM crops are bred for herbicide or insect resistance at the cost of yield[2]. Of course if insects eat the higher yielding non-GM crop, you have perhaps lower yield yet. Or if the crop is choked with weeds, the yield goes down. The non-GM crops could be sprayed with insecticide, but that is not the greenest world either. I doubt that agribusiness and farmers want to plant GM crops just for fun. Edison (talk) 19:12, 24 June 2009 (UTC)

Thank you for taking the time to respond to my query. I think that yield has the accepted meaning of 'net output', that is that any loss to pests/weeds would be factored into 'yield'. Unomi (talk) 04:51, 26 June 2009 (UTC)

"Yield" strictly refers to what a particular cultivar of a plant will produce under ideal (or given) conditions. The harvest - how much usable produce results - will depend on how far conditions departed from the ideal, as well as disaster damage (drought, flood, hurricane etc).A plant that is quite average under ideal conditions will provide a bigger harvest under poor conditions, IF it is modified or bred to repel pests, withstand diseases, or grow with less fertiliser and water. Their yield (lbs per plant or tons per acre) may be quite low compared to some other cultivars. Their main advantage is being able to grow where the natural forms of the plant would not survive. So it could be a low-yielding plant but give more in that unfavourable place than some higher-yielding plant might. Even where the chemicals are available, as in the USA, there might be more profit in a smaller low-chemical harvest, than in a larger harvest that required big investments in chemicals. As long as suitable land is available to produce the total the nation needs, at the lower yield level, it makes sense to modify for condition tolerance rather than high yields. - KoolerStill (talk) 06:41, 27 June 2009 (UTC)

Thank you for your reply, could you let me know which sources you refer to for your understanding of yield vs harvest? From what I have seen here pest damage is referred to as loss of yield and pest effect on yield which suggests that final yield has pest damage factored in. Your argument regarding profit margin increases resulting from logistical and material efficiencies ring true, but I wonder if you could point me to sources indicating that this is the case? Unomi (talk) 11:35, 27 June 2009 (UTC)

Unomi, your link in the section "Pest damage assessment...." does say "yield or harvest". I was making a linguistic distinction, to differentiate between the product ("yield") of an individual plant, and the product ("harvest") obtainable per area of land. "Yield" is, indeed, often used for both.

This UK government document (PDF) lists input cost savings on various GM crops in various countries on several continents. In some cases harvests were also increased. The cost savings involved in some cases are quite substantial. - KoolerStill (talk) 21:30, 27 June 2009 (UTC)

negative mass in general relativity

The Schwarzschild solution for the spherically symmetric vacuum Einstein equations formally exists both for positive and negative mass (for negative mass no horizon forms, and the curvature singularity at the center is naked). Negative mass solutions are excluded as unphysical. My question is: is the exclusion of negative mass solutions just an "experimental fact", or do such solutions cause some intrinsic inconsistency in general relativity? My question refers both to Schwarzschild solutions (i.e. solutions to the vacuum Einstein equations) and to non-vacuum solutions which asymptotically (for large radius) behave like a Schwarzschild solution with negative mass.XYZsquared (talk) 12:23, 24 June 2009 (UTC)

You may be interested in our article on exotic matter, which includes the concept of negative mass. We note that negative mass violates Einstein's "positive energy" condition, but that the condition is not required for the theory to hold together mathematically. As such, the exclusion of negative mass can be considered for now an experimental fact, though work has been and is being done to investigate the possibility of its existence. — Lomn 13:11, 24 June 2009 (UTC)

Naked singularities are something of a problem. There isn't a great deal of evidence for the cosmic censorship hypothesis, as far as I know, but if it doesn't hold we have some pretty big questions still to answer ("What does a singularity look like?" being the main one, I guess). --Tango (talk) 13:18, 24 June 2009 (UTC)

Does alcohol kill germs? Does silver?

Hello, there are some people around here arguing about alcohol in the Lord's supper, specifically about historical practices. Some assert that when a common cup was used, the combination of alcohol in the wine and silver in the chalice was successful in killing germs and there was thus no danger of spreading the influenza through Communion. Others, however, claim that this is absolutely false, and that the alcohol in a cup of wine is insufficient for the preventing of disease. Can anyone help me out here? 65.210.65.50 (talk) 15:05, 24 June 2009 (UTC)

AFAIK, only nanoparticle silver has anti-microbial properties, bulk solid silver does not. Eating or drinking from silverware will certainly not prevent disease all by itself. Strong wines (20% alcohol) could be alcoholic enough to have some inhibitory effect (the limit of wine strengh arises from yeast no longer being able to grow at such concentrations), but disinfectant alcohol is 70%, so 20% could easily leave viruses or spores intact.YobMod 15:22, 24 June 2009 (UTC)

It's false. There is enough alcohol in wine to have an effect, but the effect is far too slow to kill viruses before the cup is passed from one drinker to another. Any possible effect of the silver would be much slower yet. Looie496 (talk) 15:25, 24 June 2009 (UTC)

Both arguments are only half-correct (and half-wrong). Wine contains antibacterial compounds, which are separate from the alcohol. The compounds come, originally, from the grapes. So, as with most benefits of wine, it is a benefit of grapes. We just like to ignore grapes because we can't get drunk eating grapes. (Googling for a reference...) How's this? -- kainaw™ 15:26, 24 June 2009 (UTC)

A discussion recently (since the swine flu outbreak) noted that some churches are using wine with higher alcohol content with the "common chalice" and others are giving only the bread, or are using individual cups. Intinction, or dipping the wafer in the wine, is another approach, but some slobs allegedly get their fingers in the wine, and Lord knows where that finger has been. Wiping the cup between sippers seems like window dressing, given the backwash done by slobs. Edison (talk) 18:44, 24 June 2009 (UTC)

Even in nano-particle sized chunks, there is no evidence for the medical efficacy of silver (see Colloidal silver) - but this isn't just another 'quack medicine' scam - there is a particularly nasty problem for people who get suckered into taking the stuff on a regular basis: Argyria - which turns your skin permenantly a particularly ikky shade of blue/purple. The scammers are also selling gold colloids - neglecting to mention Chrysiasis - which also turns your skin blue. SteveBaker (talk) 02:20, 25 June 2009 (UTC)

It should be noted that silver compounds, such as silver sulfadiazine, have established efficacy in the topical treatment of infected burns and ulcers, and in prevention of infections (central venous catheters, for example, are often coated with silver sulfadiazine, which reduces risk of infection by 35%) and that this has nothing to do with ingestion of elemental silver or with chalices - other than being a possible source of misunderstanding. - Nunh-huh 02:31, 25 June 2009 (UTC)

What about those Silver washing machines? They inject each wash with a load of nano particles. Consumer Reports said it really works. --70.167.58.6 (talk) 17:13, 25 June 2009 (UTC)

Nanoparticle silver can definitly inhibit microbial growth - i've done the experiment, and read dozens of papers on this.[3], [4] [5] Interestingly gold of the same sizes has no effect. But preventing microbial growth does not mean it works as medicine (bleach will kill germs too, but doesn't mean it should be a supplement). YobMod 08:17, 26 June 2009 (UTC)

Returning to the OP's original question - I don't see that there is a problem here. Either you're using blind faith to get your head into the whole Sacramental union thing - in which case you're supposed to mindlessly believe that the wine is literally (not 'figuratively') transformed at that moment into the blood of Christ (it definitely says that in at least four or five places in the Bible)...which I'd presume was unlikely to harbor too many nasty bugs...or perhaps you think it's just particularly nasty wine - in which case there is really no point in bothering with the ceremony at all. Either way - a few flesh-eating bacteria should be no problem for you. SteveBaker (talk) 03:38, 25 June 2009 (UTC)

I see nothing in the OP about the faith-based elements of the Eucharist. Your response betrays considerable ignorance of the breadth of views between transsubstantiation and the bare memorial interpretation, and striking unfamiliarity with the Bible, but that's as irrelevant to this thread as any other religious or anti-religious question. The question was about food hygiene; why attack someone's faith? AlexTiefling (talk) 20:49, 25 June 2009 (UTC)

Many thanks to all for your assistance. 65.210.65.50 (talk) 15:15, 26 June 2009 (UTC)

The most important thing in this case is that most diseases aren't virulent enough to transfer through the minimal interaction of a single sip from a cup. So rituals involving this usually will not spread disease. You can get more fluid transfer just kissing somebody. Influenza might be virulent enough to pull it off though. Dcoetzee 03:05, 27 June 2009 (UTC)

Sabre wolf

I can't find a article on the sabre wolf animal that is now extinct! Does it exist under another name or is there another article? 82.203.3.4 (talk) 15:33, 24 June 2009 (UTC)

Do you mean http://en.wikipedia.org/wiki/Tasmanian_wolf ?

Hmm, never heard of a sabre wolf. Kurten & Anderson Pleistocene Mammals of North America also does not list anything that's even remotely similar. Or do you mean Dire wolf? --Dr Dima (talk) 17:26, 24 June 2009 (UTC)

Sabre-toothed tiger? Livewireo (talk) 18:26, 24 June 2009 (UTC)

Sabre Wulf?? Exxolon (talk) 21:16, 24 June 2009 (UTC)

General scientific magazines - like Science and Nature

What is the point of magazines like Science and Nature? Most people - if not all - won't understand the most articles, will they? Why don't serious scientist only read "their" scientific magazines. On the other hand, easily explained science like that of Scientific American could be more of a help for many people, since many of its articles are generally accessible.--Mr.K. (talk) 17:54, 24 June 2009 (UTC)

I rarely understand the technical details of articles in Science or Nature, but I still enjoy reading them. As long as you have a solid grounding of science in general, you can get something out of most of the articles. I find it interesting to see how research is done in fields I know little about, as well. --Tango (talk) 18:02, 24 June 2009 (UTC)

And just because someone has a doctorate in say astrodynamics, does not mean that they might not also be interested in seeing what new discoveries have been made in biology, or chemistry. 65.121.141.34 (talk) 18:07, 24 June 2009 (UTC)

These journals are great for scientists to see what really are some of the current/most important research topics happening in other fields than one's own, and science isn't as compartmentalized as the public thinks ("materials scientist" vs "biochemist", etc.). DMacks (talk) 18:16, 24 June 2009 (UTC)

Well, they've been making money pretty solidly for a LONG time - there's certainly a market for them somewhere. They aren't as unapproachable as you might first think...and they are a great way for specialised scientists to get a smattering of what's going on outside their fields. SteveBaker (talk) 00:45, 25 June 2009 (UTC)

Another Venus Flytrap question

Is it really true that venus flytraps are only truly native to an area surrounding a prehistoric meteorite impact crater in North Carolina? --90.241.27.96 (talk) 19:48, 24 June 2009 (UTC)

This is being discussed in-depth at the previous question and does not need to be re-posted. — Lomn 19:58, 24 June 2009 (UTC)

Sorry. I should have made it clearer. My question is in relation to the theories that the venus flytrap is of nonterrestrial origin which mention the fact that the VTF's natural range is in a radius around a certain meteorite crater. I wanted to know if this crater actually exists where they say it does. Thanks. --90.241.27.96 (talk) 20:06, 24 June 2009 (UTC)

I am not seeing anything about North Carolina in our meteorite article. The idea that Venus flytraps are of extraterrestrial origin is not likely to be found with merit in a respectable scientific community unless there is some other evidence supporting the theory. 65.121.141.34 (talk) 20:19, 24 June 2009 (UTC)

Flytraps are absolutely terrestrial. They are related to other existing carnivorous plants in the Droseraceae. The word "Venus" comes from the goddess, not the planet.

This seems to be a common rumor, though. The Straight Dope covered this once. APL (talk) 20:57, 24 June 2009 (UTC)

There is no doubt that these plants are related to all other life on earth - nothing weird going on there. The question about North Carolina comes about from a crazy-looking contradiction between versions of a particular book. It's already being discussed above - and I respectfully ask that THAT part of the question continues to be answered up there rather than splitting the thread in a confusing manner. SteveBaker (talk) 22:21, 24 June 2009 (UTC)

He's asking about the commonly held, but rarely documented belief that they are found near a meteor crater only. I have heard this, and can neither prove it true or false. However, I can say that it is a terrestrial plant, and if there is a meteor connection it can be explained by the extra nutrients a meteor may have provided.Drew Smith What I've done 05:39, 25 June 2009 (UTC)

The nutrient thing almost certainly doesn't hold up. The defining characteristic of carnivorous plants is that they're nutrient-deficient with respect to the soil, and thus they eat meat to make up the gap. Additional meteorite nutrients would make a plant less dependent on unusual food sources. — Lomn 14:44, 25 June 2009 (UTC)

You're slightly off in your representation of he VFT. They can survive for long periods of time in nutrient deficient soil, but it doesn't mean they will thrive. Perhaps the meteor added a nutrient to the NC soil that wasn't found in most other places which allowed the VFT to thrive, while the VFT can be adapted to survive elsewhere.Drew Smith What I've done 06:54, 26 June 2009 (UTC)

Short answer: certainly no. That is not how evolution works. Long answer: As you can read in the literature, the venus fly trap has very specific habitat requirements in the wild, for example soil really low in nutrients and regular wildfires to keep competitors (other plants adapted for low-nutrient soil) out. Your answer is full of wrong concepts of evolution and the emergence of new species, I do not even know where to start correcting it. VFTs certainly do not require a mysterious "meteor nutrient" (what should it be?!?), they just evolved to thrive in the very special conditions of their natural habitat. A meteor cannot transform an ordinary plant into a carnivorous one, less so because a meteor impact is a one-time event, which does not create any continuous selection pressure. Sure, the short term destruction can be devastating for life in the region, but all craters I know were recolonized rather quickly (in geological timescales) by ordinary plants of the surrounding ecosystem. Btw: Where is this crater in north carolina? I only did a quick search, but I couldn't locate one. Summary: This is a really dumb myth. --TheMaster17 (talk) 08:44, 26 June 2009 (UTC)

The mystery nutrient could be iridium. —Tamfang (talk) 16:49, 27 June 2009 (UTC)

Converting Contour Maps to Height-Map Data

I have a lot of contour maps (geographic maps of elevation), which are unfortunately images in "standard" formats like JPEG. Many of them are clean images, in the sense that they are only white backgrounds with black lines for elevation contours; and some text for the height markers. My desire is to turn these into data files, roughly a series of x,y, and z coordinates. Is there a good software utility for converting them to a data format suitable for data processing? My current plan involves a lot of manual labor (manually gray-scale filling between the contours, and then converting the grayscale image values to an easy-to-use CSV file or something); but this will be painful. It seems like this task must have been encountered before and automated.... are there standard approaches I'm unaware of? Nimur (talk) 20:47, 24 June 2009 (UTC)

I've seen lots of software for converting height info to contours, but never anything in the reverse direction. It would be a p.i.t.a. to write a program to do it, but certainly not impossible -- you might try the Computing Desk if you don't get any response here. Looie496 (talk) 21:03, 24 June 2009 (UTC)

Why bother? NASA has a free download of elevation data for almost the entire planet at spectacular precision. (See Shuttle Radar Topography Mission) They offer height data every 30 meters in the USA and every 90 meters elsewhere. You can download the data from their website here: http://dds.cr.usgs.gov/srtm/

The information you can get from even a pristine contour map would likely be vastly inferior...but you don't have pristine maps - you have JPEG - which is a horrible format for anything other than your family photo collection and Internet porn! I'm a programmer who does stuff like this for a living - and what you're proposing would be a very VERY last-ditch emergency, no other way to do it, kind of a thing...with not much hope of success. You can probably use standard image processing techniques to 'vectorize' the data (although because it's JPEG - you won't get great results) - then write software to make sure that every vector connects either to a single other vector - or to the edge of the map...and that vectors never cross each other. Your map will certainly not meet either criteria - so you'll have to build some heuristics to fill in the gaps. For contour lines that touch the edge of the map - you have to figure out which side of the line is higher and which is lower. and make a loop from them by connecting up a 'fake' contour that goes around the edge of the map. When that's done, you have a set of irregular polygons - one for each closed contour 'loop'. Once you have that, you can write more code that 'rasterizes' the contours from the lowest to the highest in order - filling in the interior of the polygon with height values equal to the height of the contour. Finally, you'd probably want to run a smoothing pass to get rid of the 'steppy' appearance of the resulting data.

But please - this is an utter pain in the butt - each one of those steps is fraught with special cases...when there is a vertical cliff and all of the contours smoosh together...when the vectoriser gets confused by JPEG-induced noise...when you can't determine whether one contour 'loop' represents a hollow or a peak. Just consider the simplest possible map which has a single 100' contour that goes from east to west across the width of the map...with 100% perfect software. How do you know whether the north half of the map is over 100' or the southern part? You can't! And that's the simplest imaginable case.

So - consider using the NASA data. SteveBaker (talk) 22:11, 24 June 2009 (UTC)

In rough terrain, SRTM data often has a vertical uncertainty of +/- 5m at 90% confidence (in some cases worse). There are many applications where I would trust carefully produced, locally surveyed maps to be more accurate than SRTM. SRTM is great stuff for filling in huge swatches of the Earth that have never been studied in depth by people on the ground, but depending on the application and the level of accuracy needed it may not be up to the task. (As an aside, getting +/- 5m precision while measuring from 300 km away and traveling 7 km/s is still a stunning technical achievement.) Dragons flight (talk) 22:48, 24 June 2009 (UTC)

I understand what you're saying about the lack of precision of the NASA data - and you are right in saying that a good contour map may be better - but contour maps, scanned into JPEG and converted back into elevation data doesn't come into the category of "carefully produced". The problems won't just be small precision issues - they'll be things like a hole in the ground as deep as Mount Everest is tall...in the location where Mount Everest should be! SteveBaker (talk) 00:21, 25 June 2009 (UTC)

Steve, all the above points are exactly why I was hoping to avoid writing my own software. JPEG and image-processing algorithms are usually a bad combination. Also, as you mention, the problem is underdefined/undersampled by very nature. Unfortunately, the maps I have are moon elevations (so the Space Shuttle survey is out), and I can't find higher resolution data sets than these maps. I may have to do a lot of manual data entry, because it doesn't seem like there's a good algorithmic way to do it. Thanks for your inputs. Nimur (talk) 01:55, 25 June 2009 (UTC)

Most of the problems Steve mentioned can't be fixed by software, so it doesn't matter if you write it yourself or not. It's going to be very labour intensive correcting all the mistakes and filling it the gaps that the software can't work out, even if you use the best software reasonably possible. --Tango (talk) 03:15, 25 June 2009 (UTC)

OK - it would have helped a lot if you'd said it was the Moon at the outset! There is online lunar elevation data too: http://onmoon.jpl.nasa.gov/ is the NASA site. We know for sure that your maps weren't carefully prepared by an army of guys with theodolites...so there is no doubt that your contour maps must have been generated from "DEM" (digital elevation data) maps originally - and you can't possibly "win" by reverse-engineering contour maps back into DEM format again! There have been so few elevation surveys of the moon and AFAIK, their results are all publically available...there is no way you can do better than grabbing the best thing from the web - probably in DEM, GeoTiff or 16-bit PNG format - which can all be easily converted into whatever form you want. The spatial resolution is something like 1km to 2km per pixel - which isn't great...but your contours can't possibly be any better - and I can guarantee that they are worse because any time you do anything whatever to this kind of data, you "damage" it. This paper [6] explains what data there is and where to get it from. The 'CEPS' program at the Smithsonian have people who you can talk to by email to request specific data from these various projects if you can't easily find it online. (Try http://www.nasm.si.edu/ceps/staff/sandre.cfm for example). SteveBaker (talk) 03:22, 25 June 2009 (UTC)

The source in question is the Apollo 17 landing site survey data (and similar for other landings). From what I can tell, these contours were hand-drawn, guided by stereo-photographic and preliminary radar soundings. The accuracy claimed is 10 meters in elevation, and "whatever" ("1:25000", apparently accurate to a few meters per pixel) in latitude-longitude (the scale is not actually easy to tell). Fortunately, this particular project is a "hobby" side-project, and the particular use of this historical data source is more of an homage to the missions than a scientific necessity; however, I will definitely be checking out the lunar surface surveys you linked, which probably do have better data for my needs. Thanks again, Nimur (talk) 03:49, 25 June 2009 (UTC)

What reference do they use for moon elevations since it does not have a sea level? 65.121.141.34 (talk) 13:00, 25 June 2009 (UTC)

It is not clearly stated in the Apollo 17 TPD packet, but this more recent USGS publication states "Because the Moon has no surface water, and hence no sea level, the datum (the 0 km contour) for elevations is defined as the radius of 1737.4 km." This, or some similar reference radius available in 1972, was used as the 0 elevation contour. The Taurus-Littrow hills are apparently 4000 meters above the base elevation; I will try to verify what radius contour was in standard use at the time. Nimur (talk) 15:00, 25 June 2009 (UTC)

Uranus dark spot

What is Uranus dark spot for? Is it a cycle storm happens once every 20 years. I just know Uranus dark spot is weaker than Saturn's Great White Spot. Is Neptune's Great Dark Spot a permanent storms, or it goes away once now and then. Is Saturn's Great White Spot happens every 10 years?--72.219.133.45 (talk) 21:04, 24 June 2009 (UTC)

If Uranus didn't have a dark spot in the center, then I'd be worried. :-) Butt seriously, the difficulty in answering your questions is that, unlike the Great Red Spot on Jupiter, most of the other similar formations can't be viewed from Earth, but only by the occasional passing space ship. Since this gives us very few data points, it's hard to say how old each spot is or exactly how it works. Hopefully, in the future, we will be able to put a permanent satellite in orbit about each planet, which can then relay pictures to us detailing the development, longevity, and nature of each cloud formation. StuRat (talk) 22:52, 24 June 2009 (UTC)

Can the Ref Desk really not manage to answer a question about Uranus without making that extremely unoriginal and immature joke? --Tango (talk) 23:19, 24 June 2009 (UTC)

Perhaps we'll have to wait until it is renamed Urectum.-- kainaw™ 00:22, 25 June 2009 (UTC)

Yes - but we're going to have to give StuRat extra credit for delicately weaving illicit medical advice into the answer.SteveBaker (talk) 00:41, 25 June 2009 (UTC)

The fact that every single gas giant we've ever looked at closely enough has had one of these spots suggests that they are a necessary consequence of the physics of such objects. Given how different in size, thermodynamics and composition they all are - this strongly suggests that the spots can't go away for long without being regenerated. SteveBaker (talk) 00:41, 25 June 2009 (UTC)

Perhaps they are like the topological example of hairs on a tennis ball - at at least one point they cannot be smooth. 89.240.105.155 (talk) 20:23, 30 June 2009 (UTC)

True enough, and even the Earth's hurricanes, although of much shorter duration, need to regenerate several times each year to dissipate heat from the oceans. It's interesting that such storms can last for at least centuries, in the case of the Great Red Spot. Perhaps some are even permanent, having existed since shortly after the host planet formed. StuRat (talk) 02:04, 25 June 2009 (UTC)

Neptune has the Great Dark Spot, not Uranus, but it is not permanent. The GDS often disappears, while Uranus is usually nearly blank. ~AH1^(TCU) 00:34, 26 June 2009 (UTC)

Alanine

This is the structure of alanine as given by Lehninger's Principles of Biochemistry:

                COO-
                 |
          NH3+---C---H
                 |
                CH3

However, most other sources give the structure of alanine as:

                COOH
                 |
           NH2---C---H
                 |
                CH3

I realise this is exactly the same thing but I wonder what does the difference in notation represent (i. e., does one notation emphasise a particular property of alanine?). What's the difference between the two notations? Thanks in advance to anyone who can help. --Leptictidium (mt) 21:13, 24 June 2009 (UTC)

I only have a basic knowledge of chemistry, so I'll let someone else fill in the gaps, but what's shown there is a zwitterion, a substance which can act as bases and acids depending upon the conditions they're in, and all amino acids including alanine display this property. I'll let someone else explain in more detail, though. Regards, --—Cyclonenim | Chat  22:00, 24 June 2009 (UTC)

From what I remember of my biochemistry class (which isn't much, even though it was barely 3 months ago...how sad) is that the charges on the COOH and the NH₃ depend on the pH of the solution they are in. I think the first structure you showed is at body pH, pH 7, and the second structure is at one of the extremes of the pH scale, but unfortunately I can't remember which one. 129.65.201.234 (talk) 00:12, 25 June 2009 (UTC)

Our amino acid article talks about the zwitterionic form of these molecules. The hydrogen on the COOH part is acidic, the nitrogen of the NH2 part is basic, and acids and bases react with each other. The exact conditions under which each of these is the preferred structure depends on solvent primarily and maybe other things in the solution, but not strictly the pH for these simple cases. The total acid/base effect is balanced in the molecule itself rather than a net gain or loss of hydrogen ions. DMacks (talk) 01:00, 25 June 2009 (UTC)

Also, even in aqueous solution, there will always be an equlibrium between these two forms. So even at pH7, with the vast majority of the aa in the zwiterionic form, it can still react as the other form. So it often doesn't matter which one draws, as it is always sightly inaccurate.

Oh, and the second form is not at an extreme pH, it is the structure of the solid (outside of solution). In acid or basic solutions there would be two other ionic forms (eg in strong acid, both the COOH and NH3+ are protonated, whereas in strong base oyu ger COO- and NH2)YobMod 08:12, 26 June 2009 (UTC)

Rice keeps sticking to non-stick cooker.

Should I be concerned? Imagine Reason (talk) 22:35, 24 June 2009 (UTC)

Is it an old non-stick cooker? The non-stick coating doesn't last forever. --Tango (talk) 23:17, 24 June 2009 (UTC)

And you might well ask where the non-stick coating goes. Unfortunately, you may end up eating most of it. StuRat (talk) 00:39, 25 June 2009 (UTC)

I was under the impression the non stick coating mostly wears off due to abuse like scrubbing and dishwashing. Sifaka ^talk 01:05, 25 June 2009 (UTC)

Yes, but some of it still gets into your food. I don't think there is much you can do about that. --Tango (talk) 02:38, 25 June 2009 (UTC)

Avoiding non-stick pans should significantly decrease your consumption of non-stick coatings. :-) StuRat (talk) 03:02, 25 June 2009 (UTC)

True, but it also significantly increases the amount of washing up you need to do! --Tango (talk) 03:09, 25 June 2009 (UTC)

You might try adding a little oil to the rice. BTW, what type of rice cooker is it? just-emery (talk) 01:19, 25 June 2009 (UTC)

I've seen plastic bags designed to line crock pots (food only touches bag). I've also seen (semi)-prepared foods in plastic bags that you cook by placing in a pot of boiling water. In either case, the food doesn't contact the cooking vessel. Now a rice cooker is higher temp than a crock pot since the water actually boils, and even higher still since IIRC it uses the rise in temp once the water is mostly evaporated to signal "done". So need to make sure the plastic is stable at operating temp & time. DMacks (talk) 02:56, 25 June 2009 (UTC)

Incedentally, non-stick coatings are pretty inert, undigestible stuff. Any tiny bits that end up in your food pretty quickly end up with the rest of the inert, undigestible stuff you eat; which is to say the toilet. I would not be concerned about that. But yes, after 5-10 years, nonstick pans need to be replaced... --Jayron32.talk.contribs 03:30, 25 June 2009 (UTC)

"WHERE DOES THE [NON-STICK COATING] GO?!?! WHERE DOES THE [NON-STICK COATING] GO?!?!" —Akrabbim^talk 19:27, 25 June 2009 (UTC)

The cooker looks like this one.[7] I don't see anything on Wikipedia that explains why pots should be thrown away when scratched (but invisible flakes are safe?). Thanks. Imagine Reason (talk) 12:44, 28 June 2009 (UTC)

I often cook rice in a non-non-stick saucepan. It will stick to the saucepan if it gets too dried out. So get around this by one or more of the following: a) not cooking for so long. b) putting a lid on the pot so that less moisture escapes during cooking. c) adding more water at the start. 89.240.105.155 (talk) 20:12, 30 June 2009 (UTC)

Happiness and children

Have any longitudinal studies been performed to determine whether initially childless couples who have children become happier compared to couples that adopt or remain childless? Have any of them followed the parents until the children reached adulthood? NeonMerlin 23:11, 24 June 2009 (UTC)

This Newsweek article discusses a 2006 study which claimed that "parents have significantly lower marital satisfaction than nonparents". That's not exactly measuring "happiness", though, and the study says it swung the other way on "feeling a greater sense of purpose and meaning in their lives", where the parents won. (The Newsweek article is written in the first person and I think it's inaccurate in a couple of its descriptions of what's in the study, if my memory of other descriptions serves. Here is another description of the study. I haven't found the actual study.) Another point I remember from a few years ago when this was originally reported: I believe it claimed that marital satisfaction decreased additionally with each additional child, until the dissatisfaction plateaued at the 4th child ... I think. Tempshill (talk) 02:18, 25 June 2009 (UTC)

The study is here. Algebraist 02:22, 25 June 2009 (UTC)

Technically, all couples are "initially childless" - but I presume you mean people who have a lot of trouble conceiving a child or completely fail to do so - who later have medical intervention or adopt in order to get a child. This would be a tough study to do because you need a control group who fail to do so - yet who were equally happy right up to that point in their lives. The studies mentioned above are just comparing families with and without children and that's an entirely different matter. The people who strive so hard to have children when it's very difficult may well suffer greatly increased stress - or they may benefit from the 'bonding' experience of working towards this shared goal...which makes them a very different bunch of people from the ones who merely choose not to have children and those who got pregnant easily. There are an awful lot of variables to control for - beyond the fact of being childless or not. It's easily possible, for example, that the couples who are initially very unhappy fail to push through the arduous process (not to mention, cost) of medically assisted reproduction - and perhaps they might be turned down for adoption simply because they are unhappy and thereby deemed unsuitable. Perhaps poorer people are less likely to be able to adopt or have medical help...you could easily end up merely comparing rich people with poor people and come to a conclusion that is actually more to do with money than children. Such a study would be hard to do fairly. SteveBaker (talk) 02:58, 25 June 2009 (UTC)

Do they have to be initially childless? Couldn't they have children from previous relationships? Vimescarrot (talk) 08:40, 25 June 2009 (UTC)

No, by "initially childless" I just mean that the study starts before either of them has had any children. NeonMerlin 01:19, 26 June 2009 (UTC)

The funny thing is that many couples have children to save the marriage. --Mr.K. (talk) 10:37, 25 June 2009 (UTC)

That's no laughing matter Mr.K. Cuddlyable3 (talk) 10:47, 27 June 2009 (UTC)