Wikipedia:Reference desk/Archives/Science/2008 September 13

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September 13

Unidentified Plant

File:UnkFlwr.jpg

Pic1

Pic2

Can you help me identify this plant? What I know: It has feathery light green leaves, 5 petal bloom with yellow centre, perennial, flowers are pink or white, grows tall, seems to spread easily, grows in southern Ontario.

Thanks, *Max* (talk) 00:09, 13 September 2008 (UTC).

Floated the two photos --antilived^{T | C | G} 02:33, 13 September 2008 (UTC)

Is it a form of Cosmos (plant)? Especially Cosmos bipinnatus for the leaves. If you google images "cosmos plant" you'll find some more like it. The volume of petals varies from a simple variety to hybrids. Julia Rossi (talk) 07:20, 13 September 2008 (UTC)

F-16 Fuel consumption

Quoted from a local paper:

"Depending on thrust and altitude, an F-16 burns anywhere from 200 to 400 kilos of fuel a minute"

Is this true?

The F-16 article doesn't answer the question as far as I can tell. Thanks. Wanderer57 (talk) 00:21, 13 September 2008 (UTC)

Yes, that's about right. You can google for "F-16 fuel consumption" to verify. There's an interesting table comparing the fuel consumption of different fighter variants. The consumption depends heavily on the mission, the payload at takeoff, the speed and altitude flown, etc. ~Amatulić (talk) 00:36, 13 September 2008 (UTC)

The table indicates a loiter time of 145 minutes, which would imply a fuel weight of at least (145 min)×(200 kg/min) = 29,000 kg or so, but F-16 indicates a dry weight of 8,670 kg and a maximum weight of 19,200 kg. I conclude, therefore, that the 200 kg/min figure is not actually a lower bound, and the burn rate could be a lot lower during cruise. Maybe 200-400 kg/min is a typical range, not an absolute range. -- Coneslayer (talk) 01:01, 13 September 2008 (UTC)

Kinetic energy revisited

Hi. Sorry if it looks like I'm being naïve again, but a few months ago I asked a question about kinetic energy, and I remember the following formula. This is not homework. kE=mv²; v=t•a; d=t²•a/2. Sorry I'm not good at LaTex, t= time, a= acceleration, d= distance. Anyway, here's the problem. An apple with a mass of 100g dropped from 1 metre has kE of roughly 1 joule. However, if I follow the distance formula, 1 = t²•5; t=~0.45, v=~4.47, kE=2. It should equal 1, so something isn't working. I'm not going to speculate by assuming that d=t²•a instead of d=t²•a/2, because that is probably wrong. Again, this is not homework, I would like to remind myself for myself. Thanks. ~AH1^(TCU) 00:29, 13 September 2008 (UTC)

Wait, or is it d=t²•a/2 and not d=t²•(a/2)? Oops. ~AH1^(TCU) 00:33, 13 September 2008 (UTC)

Those two expressions are equal. Your mistake is in your first formula: kinetic energy is one half of mass times velocity squared. Algebraist 00:35, 13 September 2008 (UTC)

Algebraist is (of course) correct. But you can also avoid finding or using the final velocity of the apple if you remember that energy gained = net force x distance (in direction of force). In this case the apple starts from rest and experiences a force of 0.1 kg x 10 ms^-2 (if we take g to be 10 ms^-2) over a distance of 1m, so its final kinetic energy is 0.1 x 10 x 1 = 1 J. Gandalf61 (talk) 11:02, 13 September 2008 (UTC)

Turtle Bites and Salmonella

Can you get salmonella from a turtle bite if you didn't bleed? The skin is starting to peel off, but I never started bleeding. Thanks. Nick (talk) 01:09, 13 September 2008 (UTC)nicholassayshi

You should consult a physician, because we cannot give medical advice here. Keep in mind that salmonella can enter through the mouth, for example, which is why you need to practice very good hygiene any time you're handling reptiles. If you've been distracted by a bite, it's easy to imagine touching your face or eyes without realizing or remembering it, or touching objects or surfaces that you don't think to sanitize later. -- Coneslayer (talk) 01:21, 13 September 2008 (UTC)

Agreed. Have you seen the article Salmonella especially this bit[1]? It breifly mentions contracting it through handling iguanas and turtles with a reference. Julia Rossi (talk) 05:55, 13 September 2008 (UTC)

It appears many reptiles have bad mouth flora: see for example Komodo_Dragon#Venom_and_bacteria. --Ayacop (talk) 07:58, 13 September 2008 (UTC)

Sort of an extreme example though. Komodo dragons are sort of a special case. --98.217.8.46 (talk) 08:12, 13 September 2008 (UTC)

Bird identification request

At the memoriam to deceased Wikipedian Jeffpw, there is a request to identify the birds in this photo. Please identify the birds in the photo and post the results here. Thanks. -- Suntag (talk) 04:35, 13 September 2008 (UTC)

You might find something here at Buzzards and Eagles of Thailand[2]. Julia Rossi (talk) 05:51, 13 September 2008 (UTC)

The larger bird is probably an immature White-bellied Sea-Eagle (Haliaeetus leucogaster) and the two smaller birds are probably Brahminy Kites (Haliastur indus).--Eriastrum (talk) 17:25, 13 September 2008 (UTC)

electrical circuit solving

1.why is the power transfer curve for a load resistor in a simple electrical circuit(battery,source resistor,load resistor),is not symmetrical over resistance. 2.why thevinen's theorem for solving complex circuits apply only on linear circuits 116.71.183.222 (talk) 10:58, 13 September 2008 (UTC)

These appear to be homework questions. If you have specific things you don't understand about the questions, you'll probably have better luck getting an answer, but we're not going to do your homework for you. -- Captain Disdain (talk) 12:52, 13 September 2008 (UTC)

transistor

In a transistor we observe base -collector resistance less then the other b-e junction.why?116.71.183.222 (talk) 11:03, 13 September 2008 (UTC)

See the answer to your previous question. -- Captain Disdain (talk) 12:52, 13 September 2008 (UTC)

These appear to be college-level homework questions that you want to avoid learning the answers to. I assume you're not on a scholarship, so I have to ask what is it that you're paying for? --Sean 20:16, 14 September 2008 (UTC)

Houston muscle

Is the Houston muscle present in all men, or is it only present in some? Thank you in advance for your answer. Leptictidium (mt) 13:41, 13 September 2008 (UTC)

What is the houston muscle? I've never heard of it, unless it has a more common name. Fribbler (talk) 13:56, 13 September 2008 (UTC)

Its more common name is the compressor venae dorsalis penis. DuncanHill (talk) 13:58, 13 September 2008 (UTC)

Aha, yup found it. My Google search was missspelled. Anyhoo, it's a variant of the bulbospongiosus muscle and being a variant, only some men will have it. Couldn't find percentages on how many, though. Fribbler (talk) 14:06, 13 September 2008 (UTC)

ice caps of the earth

I have seen long ago in a childrens program that if you fill a glass of water half way, and fill the glass to the brim using ice;the question being: will the glass overflow if the ice melts? the answer is no. Would'nt the same rule aply with the Earth?; if the mass of the continents is already in the equasion of the Earths oceans? —Preceding unsigned comment added by 68.114.246.137 (talk) 17:50, 13 September 2008 (UTC)

By analogy to the example you give, floating ice (like the north polar ice) will have negligible effect, but ice that sits on land and slides into the ocean can have a profound effect. --Scray (talk) 17:57, 13 September 2008 (UTC)

Glaciers being the main example of such ice. --Tango (talk) 18:11, 13 September 2008 (UTC)

Ice has a different volume than liquid water. It is not a question of mass. In the example you give, I imagine the reason it doesn't overflow has to do with surface tension, not the fact that the ice and the liquid have the same total volume, as they do not (which you can easily see if you put a fixed amount of liquid into a small container and then freeze it—it'll burst). --98.217.8.46 (talk) 18:02, 13 September 2008 (UTC)

No, it's nothing to do with surface tension. In order for the ice to float it has to displace an amount of water with the same mass as it (see Archimedes principle). When it melts, it will have the same volume as the water it displaced, so will just take the place of the part of the ice cube that was underwater and the water level won't change. --Tango (talk) 18:10, 13 September 2008 (UTC)

Huh, I guess my brain isn't working today. --98.217.8.46 (talk) 19:37, 13 September 2008 (UTC)

I'm not sure quite what you're asking, but the continents aren't floating on the ocean. There is no water underneath, just the Earth's mantle. --Tango (talk) 18:10, 13 September 2008 (UTC)

The Arctic polar ice cap is frozen ocean and so is indeed floating on sea water Jdrewitt (talk) 20:27, 13 September 2008 (UTC)

But the ice caps on Greenland and Antarctica are largely on land, so melting of this ice would indeed act to raise sea level. That is the main reason for the concern over global warming causing low-lying land to flood. More detailed discussion at Sea level rise#Glaciers and ice caps. --Anonymous, 21:10 UTC, September 13, 2008.

And don't forget Post-glacial rebound. Wisconsin is still rebounding. Saintrain (talk) 22:33, 13 September 2008 (UTC)

The raising of the sea levels has as much to do with the thermal expansion of the existing water as it does to do with melting glaciers. Plasticup ^T/C 02:26, 14 September 2008 (UTC)

Another issue not accounted for in the ice in the cup analogy is that the ice caps are bright white, and liquid ocean is dark, so a lot more sunlight is reflected off into space when there's ice than there will be in nearish future when the arctic ice cap is only visible in history books. This increased heat will cause more thermal expansion. See albedo. --Sean 20:12, 14 September 2008 (UTC)

Storage

I am in the process of sketching out a new invention, which I unfortunately cannot discuss the details of (for obvious reasons). However, my invention has certain storage requirements that I am hoping somebody could assist me with. Basically, I need a form of storage with sufficient capacity to store the exact location, and state, of every atom in a adult human's body. Can anybody suggest a form of storage which would have this capacity? If you can help with this, please let me know. Thanks John. —Preceding unsigned comment added by Jbsouth1971 (talk • contribs) 19:05, 13 September 2008 (UTC)

Um, no. You're talking about something that needs a minimum of like 10²⁷ bits of information, but probably even more than that (that's just the number of atoms in the body—so add to that some sort of x,y,z coordinate system, plus all that can go into "state", e.g. which element, ions, etc., how it is bonded with other atoms into molecules, etc., and you're increasing the total amount of data by five or six times at a minimum). To give you an idea of how much that is, Google's total capacity is more than 10 orders of magnitude (10 million times) smaller than that. In an imaginary science fiction universe the best way to store that sort of information would be in directly making an exact duplicate of the body. --98.217.8.46 (talk) 19:47, 13 September 2008 (UTC)

are you building, a "teleportation" device? Coolotter88 (talk) 19:30, 13 September 2008 (UTC)

Hi John. Maybe the guys over at archive.org could help. They need an extra 20TB of space every month.78.148.226.73 (talk) 19:51, 13 September 2008 (UTC)

Doesn't this run into a major issue with the Heisenberg uncertainty principle? Exact location and state would seem entirely impossible. — Lomn 20:07, 13 September 2008 (UTC)

There's no such thing as exact when you measure a real quantity with a finite number of bits. But there's some resolution beyond which it doesn't matter, functionally. —Tamfang (talk) 07:20, 15 September 2008 (UTC)

OK, many thanks for all your help. It would seem that looking at the atomic level was a little too ambitious! I have thought about this further and I think that just storaging the location and type of each cell would be OK. Is there a form of storage that could handle that? Thanks again! Jbsouth1971 (talk) 20:20, 13 September 2008 (UTC)

According to Cell (biology), there's about 10¹⁴ cells in the human body, that's 100,000 billion cells. A typical large harddrive currently for sale can store about one terabyte of data, ie, 10¹² bytes, so you would need several hundred of those to store meaningful data. Equendil Talk 21:28, 13 September 2008 (UTC)

OK, so this is starting to look doable. I guess I would need about 100 drives just to store a list of the cells, and more to store other information. Thanks. Jbsouth1971 (talk) 00:07, 14 September 2008 (UTC)

Well, 10¹⁴ cells, each of which need location coordinates, not just "a byte of info". Think how big a cell is, and then you know how accurately you have to specify each one's (x,y,z) coordinates. And both exact position and cell↔cell contact information are critical if you're hoping to (re)create some sort of viable organism from the data. Gotta get the right nerves talking to the right muscles, etc. DMacks (talk) 03:31, 14 September 2008 (UTC)

Thanks. So if it would need this extra information, can anybody suggest how to figure out how much information would be required to create an accurate representation of an adult human? Along with the compression I mentioned before, it is likley that each cell would only need its location to be defined relative to its neighbours, so I am not sure if that helps minimise the information to be stored (i.e. I am not sure which representation would work best). Jbsouth1971 (talk) 14:50, 14 September 2008 (UTC)

Without knowing what you will do with the info, there's no way anyone can tell you what info you will need or how accurate it has to be. DMacks (talk) 15:52, 14 September 2008 (UTC)

I can't really go into exactly what it does but, suffice to say, that it would need to be enough information that, if a human were asembled from the information, they would be identical and alive and well. Jbsouth1971 (talk) 20:12, 15 September 2008 (UTC)

How much detail do you need on the "type" of cell? How many cell types are there? I am pretty sure we don't have a clue, if you include the state of the cell. What about each cell's contact with its neighbors? There are innumerable details that contribute to the state of the organism. --Scray (talk) 21:36, 13 September 2008 (UTC)

Be still my heart. And don't breathe! Saintrain (talk) 22:30, 13 September 2008 (UTC)

I think that it will probably just need the type of cell in terms of skin, blood, brain etc. Of course, there will be sub-types of those cells, but I guess that all of the types are known. I don't think it will need the contact information, just the exact location at a given point in time. It may well be that there could be some compression here too, I think. For example, if there is a block of identical cells (e.g. all liver cells) then you would just need to store the position of the boundaries, if you see what I mean. Thanks Jbsouth1971 (talk) 00:07, 14 September 2008 (UTC)

Just warn us before you test your mass teleportation device. Plasticup ^T/C 02:24, 14 September 2008 (UTC)

Also, before you decide a teleporter is a good idea (since that's pretty much the only thing any of us can imagine you are thinking about, except for maybe soylent tostito dip) watch The Prestige (film) or read the introduction to the book The Mind's I. --Shaggorama (talk) 07:12, 14 September 2008 (UTC)

Maybe he just needs a lot of storage space and is disguising its purpose by implying teleportation. --Bowlhover (talk) 15:31, 14 September 2008 (UTC)

Thanks for all of that info, it was very enlightening. Unfortunately I really can't discuss what the invention actually is, at least not at this stage of the process. Once the whole thing is a little more advanced I will be able to unveil it. Thanks again. Jbsouth1971 (talk) 14:50, 14 September 2008 (UTC)

Assuming it's a teleporter or cloning device you're inventing, rather than, say, simulating a human on a computer, you may be interested in tissue engineering. Also, google organ printing. That is for how you'd assemble the cells. Note that it takes so long to do this that if you're not printing a rather small organ, it will die as it's being built. Also, it would be impossible to build a brain with such a machine, partially because you'd have no way of wiring the axons, and because AFAIK there's information stored on a sub-cellular level. Anyway, why start with humans? Shouldn't you make a prototype for some simple multi-celled organism, like moss, and work up from there? — DanielLC 15:51, 14 September 2008 (UTC)

Thanks. Again, without going into the details of the invention, I do think that your idea of targeting a simpler organism is a good one. I can see some problems with proving the viability of the invention, but I could work on those. Using your example of moss, what kind of simplification do you think we would get over a human? Jbsouth1971 (talk) 20:12, 15 September 2008 (UTC)

If you are creating a clone, you should get the "look and feel" of your copy working with the just genetic code. ... However, I'd assume that you would not just want a walking, talking dummy/another person but a clone who has experienced what the master copy has already experienced, and knows what the master copy knows. ... Sounds quite a bit of a challenge already. I chime in with the others who are asking you to try small[er], and simple[r] organisms. Kushal (talk) 11:05, 20 September 2008 (UTC)

Nuclear waste into space

With the problem of nuclear waste being as long lasting as it is, would not the best option be to chuck the stuff into the sun. Chemical rockets and their occasional explosions would make that into a self-inflicted dirty bomb, but, would not a rail-gun type of launch into space be practical? —Preceding unsigned comment added by 68.193.8.247 (talk) 19:46, 13 September 2008 (UTC)

See Nuclear_waste#Space_disposal. Sure, if you came up with a totally reliable way of launching it into space, that might work. But we're pretty far away from such an option. And personally I'm still dubious that launching it into space is the "best" option. A carefully managed underground repository in a remote area would still probably be easier and cheaper to deal with. --98.217.8.46 (talk) 19:49, 13 September 2008 (UTC)

Given science fiction technology, we may as well just annihilate our radioactive waste, and not bother with sending stuff into space. "Railguns" applied to space launch ain't practical, we don't have that kind of technology. Besides, cost considerations more so than technology dictate how we can realistically dipose of radioactive waste. Equendil Talk 21:41, 13 September 2008 (UTC)

Disposing of nuclear waste in space may be worth considering, and has been suggested, but chucking it into the sun would take an enormous amount of fuel (unless you waited until you can get great gravitational assists from various planets). In order to hit the sum you need to get rid of all orbital velocity you've inherited from Earth, a tiny bit left and you'll just loop round the sun and come back. --Tango (talk) 22:46, 13 September 2008 (UTC)

If you put nuclear waste in a rocket, there is a chance that the rocket can explode and send back the waste to Earth. 72.136.110.93 (talk) 23:10, 13 September 2008 (UTC)

Or blow the Moon out of orbit. What happens if we figure out how to recover and reuse that material? --—— Gadget850 (Ed) ^talk - 00:01, 14 September 2008 (UTC)

• I think we can all learn a valuable lesson from Futurama. -- MacAddct  1984 ^{(talk • contribs)} 03:08, 14 September 2008 (UTC)

Why don't we (America) just sell it to nations that are willing to reprocess it, or better yet, fix our broken nuclear policy and reprocess it ourselves? — DanielLC 15:29, 14 September 2008 (UTC)

Selling it to other nations to reprocess is sort of a political non-starter, even if one thought it was a good idea to increase worldwide plutonium inventories. Can you imagine the headlines? "US selling plutonium to Russia (or India, or China, or France)"? The only place I could imagine even contemplating getting away with it would be the UK and even that seems unlikely. --98.217.8.46 (talk) 20:13, 14 September 2008 (UTC)

Why is the UK any better than any of the other existing nuclear powers? Selling it to a country that doesn't already have nuclear weapons might be an issue, but all the countries you list have them already, so what difference does it make? Of course, you can't completely reprocess it - you're still going to have radioactive waste left, just less of it. --Tango (talk) 13:09, 15 September 2008 (UTC)

Because the IAEA won't allow that. Otherwise nuclear waste could be exported to developing countries and disposed of on the cheap, at great risk to the locals.

(edit to clarify) The UK's THORP plant is supposed to be capable of receiving and reprocessing foreign spent fuel, but you get an equivalent amount of radioactive material in return.AlmostReadytoFly (talk) 13:57, 15 September 2008 (UTC)

Nuclear explosion and X-Ray lasers

The blast element of a nuclear explosion is mostly caused by the sudden release of x-rays correct? So if we were to create an X-Ray laser like the bomb pumped x-ray laser proposed during the 80s, and it was fired relatively close to the ground, what would the effect look like? The X-rays themselves I know are invisible, but I'm assuming we would see something because the X-rays would create blast when they are absorbed by the atmosphere. ScienceApe (talk) 20:34, 13 September 2008 (UTC)

A nuclear blast has three devises that cause damage: the blast itself/expansion of gases, intense heat, and nuclear radiation. Nuclear radiation traditionally consists of alpha particles, beta particles, and gamma rays (not X-rays.) I don't think you would see much if you released a bunch of X-ray's, just like you can't see anything when they are used to photograph your teeth or bones. Unless by some chance they excite the atmosphere, which I don't think is possible. X-rays are not well absorbed by the earth's atmosphere. --Russoc4 (talk) 20:43, 13 September 2008 (UTC)

I think you are confused a little. I'm not referring to the total effects of a nuclear explosion, just the blast effects, which is different. The effects of a nuclear explosion consist of,

    Blast—40-50% of total energy
    Thermal radiation—30-50% of total energy
    Ionizing radiation—5% of total energy
    Residual radiation—5-10% of total energy

Now, I'm only referring to the blast effects, not the other three. With that in mind according to, http://en.wikipedia.org/wiki/Effects_of_nuclear_explosions#Blast_damage, blast is indeed mostly caused by the x-rays. It says "shock wave is inside the surface of the developing fireball, which is created in a volume of air by the X-rays.". Additionally the the particles and the gamma rays you mentioned appear to be associated with ionizing radiation, which is another effect that I'm not asking about. ScienceApe (talk) 20:57, 13 September 2008 (UTC)

That article is rather weak on the actual physical mechanism whereby soft X-rays actually form the fireball, saying only (of the air) "this radiation interacts with and rapidly heats it". How this actually happens is better described in this article. What's not clear to me is what proportion of the visible spectrum light is due to direct incandescence of the superheated atmosphere atoms (I confess to not really understanding what "heating" an atom really means) and what proportion is photoelectric fluorescence. This paper discusses atmospheric fluorescence due to the x-ray emissions of nuclear explosions. I guess in answer to your "what would it look like" the answer is going to lie somewhere between "discrete death beam" and "terrifying glowing blurry death sausage". Either way it's not going to reach very far (perhaps a mile). Russoc4: as these papers show, X-rays are very much absorbed by the atmosphere, the first paper saying "the X rays are absorbed in the immediate vicinity of the burst, and they heat the air to high temperatures. This sphere of hot air is sometimes referred to as the "X-ray fireball." -- Finlay McWalter | Talk 21:48, 13 September 2008 (UTC)

Interesting off-topic factoid that you should not try to verify: if your eyes are well-adjusted in a darkened room and you look at a strong X-ray source, you can see a ghostly gray light, according to Röntgen. --Sean 20:42, 14 September 2008 (UTC)

Not making nutrients as an evolutionary "tactic"

While stirring my grits this morning and thinking about incomplete proteins (no, really) it occurred to me that, as omnivores, we didn't need to make many of our "secondary" nutrients since we could just harvest them. What is the cost of making vitamins? Would such a cost-avoidance provide a significant evolutionary benefit? Thanks Saintrain (talk) 21:05, 13 September 2008 (UTC)

I'm not sure what you are talking about. There are lots of things that we evolved that we didn't "need" or there are better alternatives to what we have. I don't know the cost of making vitamins, but I do know that just taking vitamins without food, tends to not be assimilated properly. You usually need to take vitamins with food in order to absorb the vitamins correctly. Could you clarify what you are asking a little more? ScienceApe (talk) 21:16, 13 September 2008 (UTC)

I'm talking about the "old days". What is the metabolic cost of making, say, vitamin C. Did avoiding the cost of making vitamin C provide a significant evolutionary benefit? Saintrain (talk) 21:34, 13 September 2008 (UTC)

If the diet provides all of the vitamin C (your example) needed, then there would be no incremental benefit in developing the mechanisms to synthesize it. So, the question becomes how much our inability to make vitamin C limited our fitness. --Scray (talk) 21:45, 13 September 2008 (UTC)

(ec) Maybe it did. The other possibility is simply genetic drift: given a diet rich in Vitamin C, our ancestors had no need to produce it, and thus no selection pressure against mutants with inactive L-gulonolactone oxidase. Apparently, the haplorrhini, including humans, all descend from a lineage with such a mutation. —Ilmari Karonen (talk) 21:49, 13 September 2008 (UTC)

To emphasize what was just said, it isn't that losing the ability to make vitamin C was beneficial, it was that there wasn't any selective pressure to keep the synthesis genes. When random mutations knock out the gene's function, the animal can still survive, and pass on the "dead" gene to its offspring - it's not better than one who can, but it's not dead, either. This was how the essential amino acids were explained to me. Since humans have historically gotten enough of most of the amino acids in the diet, there isn't any pressure to keep the synthesis genes around, and you slowly lose their function. The pathways which require more genes to make are lost first, as there is more chances that one of the genes will be knocked out by random mutation. -- 128.104.112.147 (talk) 22:00, 13 September 2008 (UTC)

There's a thread on the "Darwin-L Message Log" on this very topic but it, too, was just hand waving and diarrhea and polar bear livers(!?). Noone answered the question "What is the metabolic cost of making vitamin C".

The best that several variations of google(metabolic cost liver ascorbic "vitamin c" synthesis site:.edu) turned up was that vitamin C was so common in other species were the suppositions were that it was very important and/or very cheap to make. (Lots of veterinary schools because humans don't make it. (Calves can make it by day 7!)) Lots of taking Dr. Pauling's name in vain, too, 'til I added the "site:.edu". What's a better set of search terms? Saintrain (talk) 01:09, 14 September 2008 (UTC)

You might want to look at the papers linked from the pertinent page on OMIM. - Nunh-huh 01:17, 14 September 2008 (UTC)

That is a very cool site. Thanks! There's all kinds of info there. Never realized how universally important vitamin C is, even to yeast. (There's even a speculation that the lack of vitamin C resulted in a higher oxidant-related mutation rate in Hominids!) But it's hard to find the cost of v-C biosynthesis in humans ('cause we don't do it). I'm about to give up. There is a reason why I didn't study biology. :-) Saintrain (talk) 00:33, 15 September 2008 (UTC)

Your best bet may be to look at vitamin C synthesis in presimians, as they are the most closely related creatures to humans in which the pathway may have been studied. - Nunh-huh 03:31, 16 September 2008 (UTC)

OMIM is very cool, and since he died recently I'd like to point out that OMIM was created and largely written by Victor McKusick, widely regarded as the father of medical genetics (and a wonderful human being who will be sorely missed). --Scray (talk) 00:23, 16 September 2008 (UTC)

Thanks for pointing out our article. I've fulfilled my "learn something new every day" obligation... - Nunh-huh 03:33, 16 September 2008 (UTC)

Only marginally related to the discussion, but reading the heading I thought that perhaps among plants being made of hard to digest fiber and some species offering low nutritional value, maybe that was an advantage to not being eaten up. Well until something evolves to eat them; food sources rarely stay unexploited.

Why is 16:9 superior to 4:3?

I look at screens all day. So do most people I know. It seems we have made a choice as a society to go with a wider, shorter resolution rather than the more square-like box. I can think of 2 reasons why this doesn't make sense:

1) We are tall, thin beings. A wider resolution impedes caturing our counteance on screen. It is disturbing to see so much landscape left and right of a human figure in the center. 2) Reading is always easier when done vertically. If a line becomes too wide it is too easy to get lost when trying to find the next line, and, far more importantly, it hinders speed reading. Sucking up short phrases is easily done in a vertical newspaper format, no inner voice required. Sappysap (talk) 22:40, 13 September 2008 (UTC)

It is not. 16:9 is a compromise TV aspect ratio between standard 4:3 and 2.35:1 movie aspect ratios. It is already not a very good solution for TV broadcast, because now you have black-bars everywhere, and when you apply it to computer monitors it's even worse. Sure now you could watch movies with less black bars but as you have said reading web pages become much more painful and whatever you have gained in less black bars when watching movies you have lost it in fixed-sized web pages that leave 50% of your monitor blank. It's mostly a fad (and this can be extended to those 16:9 cameras), and IMHO what you lose (precious vertical resolution) is much more important than what you gain (less black bars when watching movies, which I hardly ever do anyway). --antilived^{T | C | G} 23:47, 13 September 2008 (UTC)

Some computer monitors (have have a rather nice Dell one) allow you to rotate a 16:9 through 90 degrees, making it a stringy 9:16. At least for text-based stuff like web-browsing and word processing that turns out to be rather nice. -- Finlay McWalter | Talk 23:52, 13 September 2008 (UTC)

Isn't our natural range of vision more oblong? Presumable the most acute portion of our vision is an ellipse inside the larger ellipse of our total range, and the largest quadrilateral that can be inscribed in that ellipse is a rectangle. Plasticup ^T/C 03:10, 14 September 2008 (UTC)

It's better for pictures as it corresponds more to how we view the world - up and down aren't as important as left and right. Holding my fingers up I can see about two and a half times as much or more sideways with both in view at the same time as I can up and down. But yes I agree, for reading it's no good currently. There is a proposal to support columns of text better in HTML so one automatically gets one, two or more to fit the screen complete with text flowing between them. At the moment doing that is a pain which is why it isn't done more frequently. Dmcq (talk) 09:22, 14 September 2008 (UTC)

I've actually held off on buying a new laptop partly for this reason. I'm hoping that the fad will blow over, but maybe I'm deluding myself. I've always suspected that part of the reason is that screens are marketed by diagonal instead of area. A 16:9 screen with a given diagonal is about 11% smaller than a 4:3 screen with the same diagonal and correspondingly cheaper to manufacture. It's a good thing digital cameras are marketed by an areal unit (megapixels) or we might be deluged with widescreen digicams also. -- BenRG (talk) 11:47, 14 September 2008 (UTC)

It's unlikely to "blow over", seeing as how 16:9 has very wide support from the LCD TV industrial base. But I think the change to 16:9 is actually a good thing; I've owned five 4:3 laptops and two 16:9 laptops and I find the 16:9 laptops much more esthetically-pleasing. For one thing, the screen much more closely approaches the golden ratio (being 1.78 rather than 1.33, and the golden ratio being 1.62). Also, when opened, the entire "height" of the laptop (screen height plus base depth) is much less than the far-"oversquare" effect you get with a 4:3 laptop. I'm not sure I'd want to go any wider, but I'm very pleased with the transition to 16:9.

Atlant (talk) 16:31, 15 September 2008 (UTC)

Good or bad, I can't imagine it blowing over. Not only is 16:9 closer to the natural aspect ratio of a keyboard, it's more like the movies, and nowadays, it's more like TV. For better or worse, I think that those are unstoppable forces in marketing and fads. APL (talk) 03:12, 16 September 2008 (UTC)

Masturbation

At what average age do girls start masturbating? —Preceding unsigned comment added by BellyGrease (talk • contribs) 22:41, 13 September 2008 (UTC)

See Masturbation#Masturbation frequency, age and sex (fourth paragraph). Zain Ebrahim (talk) 22:49, 13 September 2008 (UTC)

end of the world : december 2012?

hi guys, i am curious about what is the concensus among scientists about all the predictions that the world may end on 2012 because of all the clues that point to that happening, like the sun spot cicle ending, poles shifting, the mayan prophecy, global warming...and all that...and also the LHC possibly creating a black hole!!! thank you! —Preceding unsigned comment added by 24.91.11.185 (talk) 22:52, 13 September 2008 (UTC)

See Wikipedia:Reference desk/Archives/Science/2008 August 15#about 20 dec 2012. There are some links to older questions in there too. Zain Ebrahim (talk) 23:00, 13 September 2008 (UTC)

Grooooaaaaaaan. See [3], [4], [5], [6],[7], and [8]. --Bowlhover (talk) 23:21, 13 September 2008 (UTC)

lol, thanks guys. but also...i think it is too much of a coincidence that the mayan calendar ends in 2012, terrence mckenas' whatever diagram ends in 2012 too, (the one that is based on the i ching), the LHC poses a minimal threat of creating a dangerous mini black hole and nostradamus has a prophecy about this machine, look it up on youtube. also the sun ending its current sun spot cicle, the solar system aligning itself with the center of..the galaxy i think. so there is a lot of stuff that seems correlated with that date. i am a skeptic too...but the world just seems so close to ending...i mean, the war in irak and stuff...i bet a bunch of countries hate the US and are planning evil things against it. like a nuclear attack , a viral attack and what not. —Preceding unsigned comment added by 24.91.11.185 (talk) 23:57, 13 September 2008 (UTC)

The Mayan's did not predict that the world would end in 2012. That is a total fabrication. I spoke to Dr. Mary Miller about this just a couple years ago, and she is widely regarded to be the foremost authority on pre-Columbian Mesoamerica. Plasticup ^T/C 00:01, 14 September 2008 (UTC)

as far as i know their calendar abruptly ends in december 2012...but i mean, i don't want the world to end. so if all this is just pseudoscience then i'm glad.

thank u guys for all your answers! —Preceding unsigned comment added by 24.91.11.185 (talk) 00:06, 14 September 2008 (UTC)

Also, the sunspot cycle repeats every 11 years, so this wouldn't be the first time. ~AH1^(TCU) 00:39, 14 September 2008 (UTC)

OK, let's go:

• sun spot cycle ending

The Sun has a 9-14 years cycle of activity. It's not really precise, and if one were to end in 2012 it would be just a coincidence.

• poles shifting

Completely unpredictable when it will happen.

• Mayan prophecy and calendar

The prophecy is a fabrication and this has been debunked several times.

• Global warming

2012 has no relation to global warming.

• LHC creating a black hole

Pretty much debunked. There's nothing to fear.

• Nostradamus prophecy

Nostradamus is a joke. There's no "prophecy" worth bothering. They're always found in hindsight and are usually passages vague enough to fit a lot of situations - just like bible and other prophecies.

• the solar system aligning itself with the center of the galaxy

This makes no sense. Two points are always "aligned". Planets alignment are worthless too.

• the world just seems so close to ending

Nah, we've been through much worse times. We're in a relatively peaceful time, really, and throughout history there has always been people claiming "the world is just about to end, you just have to look at the signs". Yet, nothing ever happened. Why do people always forget failed predictions? For example, Christians have been thinking the Second coming was going to happen within their lives for centuries.

So you see, this is not even pseudoscience. It's bullshit. Just move on and don't bother with these apocalypse fears, because they have always been wrong throughout history. But if someday you see scientists reporting an actual natural threat, then you have reasons to believe them. — Kieff | Talk 02:08, 14 September 2008 (UTC)

If you look hard enough, any year has peculiarities that, if isolated, seem surprising. I can easily claim that 2009 is going to be the best year on record by pointing to the 1909 article. Just look at what happened during that one short year! The People's Republic of China was established, and it was this party that ended 2000 years of monarchy in China. Dessau became the first radio broadcaster. Robert Peary became the first person to reach the north pole. The Pearl Harbor base was founded in November. The person accused of setting fire to the Reichstag was born. All of these events are much more well-known than the "predictions" involving 2012! Who doesn't know about the ROC? Who doesn't know about radio broadcasts, Peary, the Reichstag fire, or Pearl Harbor? But who, without having read about the "apocalypse", would know about some obscure Mayan text or McKennas' graph?

It's true that the events I mentioned do not make it more likely that 2009 will be the best year on record, but celestial alignments, the LHC, the solar maximum, and pole shifts don't increase the likelihood of an apocalypse either.

I assume that this is the Youtube video you're referring to. The Nostradamus prophecy, which does not mention the year 2012, reads:

"All should leave Geneva. Saturn turns from gold to iron. The raypoz will exterminate everything. There will be signs in the sky before this."

Only the first sentence suggests the LHC; "raypoz" is not a French word and is not always interpreted as "positive ray". This website, for example, believes it means "Christ". The poem might as well be construed as a prediction of a war in which Switzerland is taken. As for the other passages the video quotes, none of them accurately describe an engulfment of Earth by a black hole. --Bowlhover (talk) 05:14, 14 September 2008 (UTC)

From a scientific standpoint, which plant is the most important?

By "important" I mean what species of plant has the most value from a guys in a lab coat researchable, medicinal, and physical law standpoint? Which lends itself best to the most rigorous scientific tests, yet can still make and cure just about anything?Sunburned Baby (talk) 22:58, 13 September 2008 (UTC)

I'll nominate arabidopsis thaliana aka thale cress. Google Scholar returns 680,000 hits for "arabidopsis", that's a lot of scholaring! It's widely considered a model organism. Doesn't really cure stuff though. Franamax (talk) 01:43, 14 September 2008 (UTC)

Interesting question. On a whim, I checked soybean and got 996,000 hits. Of course, since oak gives us more than a million hits, I'm not sure how good a gauge Scholar really is. Wheat gives us two million hits. Matt Deres (talk) 02:08, 14 September 2008 (UTC)

Heh. Turns out there are a lot of people named Wheat doing research out there; forget that one! Matt Deres (talk) 02:09, 14 September 2008 (UTC)

Maybe so, but all those people named Wheat are undoubtedly descendants of wheat farmers, so if not for wheat we would have a HUGE loss of valuable researchers. Therefore, those hits still definitely count! --Scray (talk) 04:55, 14 September 2008 (UTC)

But why are the people named Potato being discouraged from going into scientific research fields? Systemic bias? Franamax (talk) 17:09, 14 September 2008 (UTC)

It very much depends on how you define important. Arabidopsis was the first plant to have its genome sequenced and widely used in genetics studies. (And there are no researchers named Mr. Arabidopsis) Important food crops such as soybean, maize, rice and wheat attract attention from agronomists because of their importance to the world, and also from geneticists because of their very complex genomes. And by historical scientific importance, you could think of the pea also, since that's where Gregor Mendel first studied genetic inheritance. Franamax (talk) 17:09, 14 September 2008 (UTC)

The effects of Ocean Nuclear Bomb Testing

What are the effects of the Nuclear Bomb Testing on the Pacific Ocean environment? Some water is now radioactive, so how long does it takes for the radioactive water to become non-radioactive water? 72.136.110.93 (talk) 23:04, 13 September 2008 (UTC)

If the water had become radioactive then more by taking up products of the fission, less by being irradiated. Anyway, the water soon mixes. The problem is the island soil that took up long-lived fission products. See that article for some ideas. On a similar note, there are still forests round Munich where collecting of mushrooms for culinary purposes is still discouraged, twenty years since Chernobyl, and more to the east it must be worse. --Ayacop (talk) 14:01, 14 September 2008 (UTC)

Our article, Pacific Proving Grounds, does not mention water contamination for the reasons stated above. More precisely, you need to define "radioactive water" and "non-radioactive water" before you can proceed. Seawater is water (Oxygen and Hydrogen) with many disolved substances (ions and some non-ionic molecules.) The readiosctivity results from radioactive isotopes of some of the atom in the water or in the disolved substances. There is a natrual background of radioactive isotopes, so one answer to your question is "never." If you define "non-radioactive" as the point at which the water near the testing ground is at or very near the background radiation, I would guess that this happens within weeks due to radioactive dacay and dilution.If you ar worried about health effects, you will need to analyze individual elements like iodine, but even these will drop to background quickly due to dilution. -Arch dude (talk) 14:23, 14 September 2008 (UTC)

The water isn't the problem—the ocean is just too vast not to dilute such effects to the level of background radiation within a short amount of time. --98.217.8.46 (talk) 15:31, 14 September 2008 (UTC)