Wikipedia:Reference desk/Archives/Science/2007 November 6

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[edit] November 6

[edit] Hearing own voice

Why is it strange to hear our own voice? 217.129.241.186 01:10, 6 November 2007 (UTC)

Because you normally hear your own voice as it is carried through the tissues and bones in your skull, as well as through the air, which is the only part you hear when you listen to a recording of yourself. Someguy1221 01:30, 6 November 2007 (UTC)
Which helps to explain why people with hearing loss often find it hard to make themselves heard to other people. They can hear themselves ok through their head bones, and they think the listeners can hear them just as well, but what listeners hear when a person is talking is not what the person themself hears. Being often asked to "speak up" is sometimes a strong clue that it's not the listeners who are going deaf, but the speaker. -- JackofOz 20:27, 6 November 2007 (UTC)

[edit] Olestra formula

While reading my chemistry textbook, I passed a short reference to Olestra, which made me think about going to that article. When there, I wondered about the chemical formula; since it's not in the article, I searched Google, but found virtually nothing. Anybody know the chemical formula (or formulæ, since it appears to have variable numbers of fatty acid chains) for Olestra? Nyttend 01:52, 6 November 2007 (UTC)

And just to make it completely obvious: I'm not asking for homework help here :-) It's not even something I'll be tested on. Nyttend 01:57, 6 November 2007 (UTC)
http://www.scientificpsychic.com/fitness/fattyacids1.html --Dacium 03:11, 6 November 2007 (UTC)
Here is another: http://sci-toys.com/ingredients/olestra_2.gif. Tim Q. Wells 05:00, 6 November 2007 (UTC)

[edit] DNA polymerase requires a "primer"?

I was looking into any information I could find on DNA polymerase since I'm currently taking a Cell Biology course, and I was wondering why exactly does DNA polymerase require a primer? I already understand the basics, but I am looking for a little more in depth explanations. Wilt0057 01:52, 6 November 2007 (UTC)wilt0057

Did you look at the DNA polymerase article? It currently reads: "DNA polymerase can only add free nucleotides to the 3’ end of the newly forming strand. This results in elongation of the new strand in a 5'-3' direction. No known DNA polymerase is able to begin a new chain (de novo). They can only add a nucleotide onto a preexisting 3'-OH group. For this reason, DNA polymerase needs a primer at which it can add the first nucleotide". I'm not sure you need more than that. Or do you need to know why it requires a 3'-OH substrate? If so, you need to research about substrate specificity for active sites in enzymes. David D. (Talk) 02:40, 6 November 2007 (UTC)


[edit] Magnetopneumodynamic Drive - I'm gonna build me one! (Maybe)

Thanks again to Graeme and Carnildo for the answer above.

Now I know it's possible (in principle) I'm going to try to build a zeppelin model with a battery-powered MPD.

What's next is whether it's possible to use a circular form for the thruster rather than triangles/rectangles. I'm thinking of a concentric circle or cylinder system that would be mounted in pairs parallel to the long axis of the zep. Remote-controlled rudders at the rear of the drives would give directional control. Any comments/suggestions appreciated.203.21.40.253 02:51, 6 November 2007 (UTC)

You won't succeed. There is absolutely zero chance of you getting something that works from a design like that. These 'lifter' things provide absolutely microscopic amounts of thrust - they have to be made of the lightest possible materials and be driven by huge voltages and currents. This means you couldn't even power one from a car battery - let alone a couple of AAA's. Look at some of the experimental setups people use. Not one of them has the power supply actually on the lifter - they always trail a couple of wires from some god-awful-large transformer with mains supply going into them! If you truly mean to use the lifter as the 'thrust' motor (as opposed to a lift motor) for a lighter-than-air balloon, then at least the lifter doesn't have to carry the weight - but consider the size of balloon you'll need to lift something much heavier than a car battery - then consider how much drag a balloon that big is going to have - then look back at the microscopic amount of thrust you get from a 'lifter' and consider how even the lightest of breezes will overcome it's pathetic thrust. Honestly, you truly don't stand any chance whatever of getting this thing to work. This technology is nothing more than an amusing party piece. Beware of the large armies of nut-jobs out there claiming that there is something magical going on here - anything from "quantum levitation" to anti-gravity to using the earth's magnetic field to power the thing...the distinguishing feature of all of them is that the best they can do is a very light lifter with power coming from the ground that can just barely lift its own weight. SteveBaker 17:59, 6 November 2007 (UTC)
No worries about the "nut-jobs" Steve; I knew what the Mythbusters would find before they started. However, the model set-up for the "hybrid" at the Blaze labs site (external link at Ionocraft article page) seems to show that the thing is do-able. Your point about the thrust to drag ratio is the obstacle I was concerned with. Exploitation of the on-board power supply is the crucial issue. I think varying the planar forms of the ionising system may be the way to go in enhancing air flow. That's where I'm looking for any guidance people can offer. Retarius | Talk 01:17, 7 November 2007 (UTC)
Well, if you aren't yet convinced, let's crunch some numbers. According to ionocraft, the force (in Newtons) exerted by the motor is the current in amps multiplied by the air gap in meters divided by 2x10-4. It also says that the air gap needs to be about 1mm per thousand volts applied to it. So roughly - the force from the lifter in Newtons is one fifth the current multiplied by the number of kilovolts.
Let's suppose you want you craft to run on ten AA batteries and let's assume you get 100% efficiency. You've got only 15 volts and you can't have 0.0015mm air gap! Let's assume you step up your voltage to 15kV using some kind of circuit so you can have a more reasonable 1.5 centimeter air gap. You get about 3 Amp/hours from a AA battery at 1.5 volts and you can pull about 15 Amps @1.5v without it melting or whatever. But with 1000 times that voltage, you get 1000 times less current - but you have 10 batteries - so you'll have about 0.15 amps at 15kV - sadly, the batteries will die after 20 minutes of flight time - but maybe that's OK.
So the force from the lifter can be no higher than 0.15*15/5 = 0.45 Newtons - that means it could lift a weight of about 45 grams against gravity. Sadly, a AA battery weighs 23 grams and we we have 230g of batteries alone...so this simply isn't going to fly even with the most optimistic possible numbers. (In truth, to push the voltage up from 15v from 10 AA's in series up to 15,000 volts will require some fairly serious electronics - that'll add a ton of weight and it'll be horribly inefficient.
But never mind - you don't want to use the lifter to lift the dead weight of the batteries - right? You're going to have a helium balloon carrying the weight and the lifter turned sideways pushing it forwards. A helium balloon can lift about 1kg per cubic meter of gas. By the time you have a quarter kilo of batteries, plus electronics, lifter and gas-tight envelope, plus radio control gear - you'll be well over 1kg. So we're looking at a zepplin-shaped balloon well over a meter in diameter.
So - what drag will this thing have? The relevent formula (from Drag coefficient) is that Force = Cd x 1/2 x rho x A x V2. Force is the 0.45 Newtons our lifter will generate. Cd will probably be about 0.3 if you are really careful (better than most cars - worse than a perfectly smooth sphere). Rho is air density - about 1.22, A is the cross section - let's say about one square meter. So the speed your zepplin will go (with the most optimistic possible numbers) will be: sqrt(0.45/(0.3x0.5x1.22x1)) ...hmmm - maybe 2 to 3 miles per hour. Wow! That's actually a lot faster than I guessed. However, in even a 1mph cross-wind - the thing will be utterly unmanageable.
But that's an insanely optimistic estimate. The trouble is that we have no estimate for the energy losses in boosting a 15 volt battery pack up to 15,000 volts. Sadly, from our article: "Ionocrafts capable of payloads in the order of a few grams usually need to be powered by power sources and high voltage converters weighing a few kilograms". Well a 'payload' of a few grams in a vertical lifter means a thrust of a few hundredths of a Newton in the horizontal direction. So if we toss out my battery calculations and say that we need a FOUR cubic meter balloon to lift a 3 kilo power supply plus one kilo of other stuff (bigger envelope, bigger control vanes, etc). And if we downgrade the thrust estimate to 'a few grams' - ie maybe 0.03N, then re-run my drag calculations with a much bigger cross-sectional area - and now your zepplin is moving at a half mile per hour. Even a light draft inside a building will stop the thing dead in it's tracks.
I'm betting the thing would bob around in air currents and you'd hardly be able to tell whether the engine was turned on or off.
Someone needs to double-check my numbers...but since it's going to cost you a lot of time and effort to find that out experimentally - it's really worth checking. IMHO, it's a waste of time to even try.
SteveBaker 03:02, 7 November 2007 (UTC)
I appreciate your time taken, Steve, and I don't dispute the above. That's why I'm looking to explore the basic design of the thruster. The extant models are too weak to bother with and I only intend to test-bed the thing unless and until it shows a useful result in improved thrust.

203.21.40.253 03:43, 8 November 2007 (UTC)

[edit] Artificial oil production

Assuming that all one needs is a source of carbon and hydrogen and energy, how much oil, natural gas, etc. could be produced per day using nuclear reactors for no other purpose? Dichotomous 04:27, 6 November 2007 (UTC)

That's equivalent to asking "how much more energy do nuclear reactors produce than fossil fuels?" because the energy to form a fossil fuel would be around that released by breaking its bonds. So from [1] we see that most fossil fuels release about 50kJ/g, and from [2] we see nuclear reactors release about 2x10^9 kWh/ton = 7x10^6 kJ/g. Great, but we don't use much material to power our reactors. The power output of a nuclear reactor is about 3x10^5 kW by quick google search, so we find that a nuclear plant can ideally produce about 10^4 g/s of fossil fuels, or 10kg per second. However, I don't think we actually have a process that can make fossil fuels in any efficient way, so our actual yield will be much less, but this is the theoretical maximum yield. SamuelRiv 04:53, 6 November 2007 (UTC)
I believe a couple of scientists in the UK about ten or fifteen years ago demonstrated a method of crude oil production using high pressure and temperature. From your calculations it appears retaining an oil based energy distribution system is not threatened by exhaustion of naturally occurring petroleum, oil, natural gas, etc. Dichotomous 05:07, 6 November 2007 (UTC)
I have always wondered why it is not possible to synthesise hydrocarbons from their constituent parts of carbon and hydrogen. For example Propane (C3H8) is just 3 carbon atoms and 8 hydrogen. How would one make them join up and form a propane molecule? I am not an expert at chemistry by any means but know the very basic basics. Also, why can CO2 not be broken up into oxygen plus carbon? I'm guessing the energy input required to do these things would outwiegh the benefits? GaryReggae 10:24, 6 November 2007 (UTC)
In terms of lubricants versus fuel the cost might be justified in the absence of substitutes or synthetics based on something else when naturally produced petroleum runs out. Even if there were more to it than just a high pressure, high temperature cooker and many steps involved, the need for carbon based lubricants and fuels may never go away. Dichotomous 12:20, 6 November 2007 (UTC)
Plus hydrocarbons have other uses, such as in plastics, paints and other such thingsGaryReggae 13:00, 6 November 2007 (UTC)
Imagine your great, great, great, great, great granddaughter complaining about the need to use so much fusion power to replace natural oil that the cost of her cosmetics are beyond reason, in addition to the cost of recharging her car... and blaming it all on the excesses of good old great, great, great, great, great granddad. Dichotomous 15:31, 6 November 2007 (UTC)
My car already uses synthetic oil - it's great stuff - it lasts three times as long as regular motor oil and it can be recycled more easily. The more interesting question is how chemical plants that use hydrocarbons as feedstocks for making plastics and such would fare. But as has been discussed elsewhere on the reference desks recently, we simply cannot afford to burn all of the oil we have left because of the greenhouse problem - so if we DO manage to save the planet by ceasing to burn oil, we'll have PLENTY left for making plastics and such like. SteveBaker 03:22, 7 November 2007 (UTC)

[edit] Global warming

Until recently I never had problems with kudzu, weeds or grass if I was away for a month or six weeks and returned to find that period of growth in the back yard. Where can I find a chart or graph which shows the rate of increase in plant growth (such as grass and kudzu, land based, and algae and coral, water based) per rate of increase in atmospheric CO2, to view the point plant growth would simply be outpaced by the production of excess CO2? Dichotomous 04:44, 6 November 2007 (UTC)

[edit] Choice

I apologize for posting this here, believe me. It will give some of you a headache, and not the good kind. Beyond the two factors of genetics and environment (experiences etc.), is there anything else, some third factor, that can account for our next choice in life? Sappysap 04:50, 6 November 2007 (UTC)

Free will, according to proponents of religion, and quantum mechanics, according to proponents of the quantum mind. Neither is widely accepted by scientists as a phenomenological explanation. SamuelRiv 04:55, 6 November 2007 (UTC)

"Choice" can be a problematical way to describe behavior since it leads some people assume that humans have a supernatural ability to escape determinism. Philosophers such as Daniel Dennett have explored the idea that it is more neutral to say that our brains give us the ability to control our behavior based on past experience. --JWSchmidt 05:42, 6 November 2007 (UTC)

See Randomness#In_biology. Besides the freckle example I gave there, another example is sexual orientation. Identical twins raised in the same home should have identical genetics and environment, yet don't always have the same sexual orientation. Thus, we know there is a random influence at work. (Note that, in this case, it may be truly random or simply following a pattern too complex for us to recognize.) StuRat 11:21, 6 November 2007 (UTC)
I'd rather attribute it to chaos (in the mathematical sense) than randomness - but I'm almost sure that our free will is an illusion. The mind clearly works on multiple levels and I strongly suspect that the conscious level that we're aware of is merely rationalising choices which a more mechanistic mind made at some lower level. There are so many ways in which lower levels of thought processes have been shown to actively disguise things from the higher levels. Things like when you move your eyes very rapidly across a scene, the signal from them is actually cut off - and your brain 'fills in' the experience of the "missing video signal" from memory and imagination. Similarly, the effects of our relatively slow reaction times are distorted by our minds to make it seem like things happen instantly without a delay. There are all sorts of ways in which our conscious mind is lied to by the lower levels - and choice or 'free will' seems to me to be just another one of those things. SteveBaker 22:52, 6 November 2007 (UTC)
More reason to avoid thinking about free will only in terms of behavioral choice. We generally associate "choice" with conscious brain activity, but the fact is, we cannot be consciously aware of most of our own brain activity. If we think about free will in terms of behavioral control then we can be comfortable with the idea that our brains can produce useful behavior based on past experience ("we" are in control) even when much of that control over our behavior is rooted in unconscious brain activity taking place outside of our rather limited domain of introspective awareness. I think the powerful illusion is that we are conscious of what we take to be "free will". If we expand our concept of "free will" to include its foundation in unconscious brain activity, then we do not have to call the brain's ability to adaptively control behavior an illusion. --JWSchmidt 22:25, 7 November 2007 (UTC)

[edit] electric vehicles for the post office

If electric vehicles offer such and advantage why hasn't the post office started using them or the candidates started touting electric vehicles for the post office? With all the stop and go driving and the large number of vehicles, if converted to electric, do a lot for global warming, or is this just a farce as well? Clem 09:01, 6 November 2007 (UTC)

In England, postal delivery rounds in suburban areas are often carried out on foot or by bicycle. However, electric milk floats have been used for many years for door-to-door deliveries of milk because they are quiet and their limited speed and range is not a problem. Gandalf61 10:52, 6 November 2007 (UTC)
Electric vehicles don't necessarily help with global warming. If fossil fuels are burnt to make the electricity, and a good deal of that electricity is lost during delivery and storage, then they can even be worse than an efficient internal combustion engine. If the electricity is made by a nuclear reactor or some other method which doesn't release hydrocarbons, then electric cars may help. StuRat 11:11, 6 November 2007 (UTC)
The huge advantage of electric vehicles in stop/start applications like door to door delivery is that you get regenerative braking more or less for free. This means that for postal runs, an electric vehicle would be massively more efficient than a gasoline car - even if its batteries are recharged by an oil-fired power plant. I don't know why they don't use them. Their routes are short enough that the limited range of an electric vehicle would not be an issue and they can have one central recharge point. As Gandalf61 says, electric milk delivery vehicles have been around in the UK for many decades (certainly they were around when I was a kid in the late 1950's). The only sound those things made was a 'kerchink, kerchink' of the milk bottles rattling...and when they switched to delivering milk in cartons...nothing...dead quiet. SteveBaker 13:00, 6 November 2007 (UTC)
Assuming in the States (and probably applicable for most places), there's a both a cost and availability problem. For one, it's expensive to replace that large a fleet of vehicles, and the vehicles are individually more expensive than those they're replacing. For two, electric cars aren't readily available on the market. Making matters worse, postal vehicles generally prefer right-hand-drive (opposite the norm), making the availability problem worse. Unfortunately, the quick solutions for 1 and 2 are in opposition to each other: the solution to cost is to upgrade very gradually; the solution to availability is to commission a big run of specialized vehicles.
The problem is worse for rural route carriers, who tend to use self-owned non-standard vehicles. In addition to the exacerbated cost/availability issues, they're also more likely to run into the problem of electric car range -- I would think a 200+ mile daily route is quite possible in some areas. — Lomn 14:14, 6 November 2007 (UTC)
Besides the regenerative braking pointed out by Steve, the other huge advantage of an electric vehicle for postal delivery would be avoiding wasting all that energy idling an internal combustion engine while the vehicle is stopped. And both of those advantages are also available in hybrids, so issues about availability, range, charging time, and questionable cleanliness of the electrical supply don’t exist as excuses for not at least switching to use hybrids for all postal delivery. Unfortunately, in the U.S., a bill requiring a switch to hybrid postal vehicles would almost certainly just get vetoed by Bush, who only recently started admitting that global warming is even real. Hopefully we’ll get a president who takes global warming more seriously soon. (As a disclosure of my biases, I’m a very proud Prius owner.) MrRedact 17:39, 6 November 2007 (UTC)
But the US post office already uses very non-standard vehicles. Getting manufacturers to build specialist vehicles is not that hard when you can put an order in for a few tens of thousands of them with a good likelyhood of them being in service for 30 years. Those funny little RHD jeep-like things are unique to the postal people - the only ones you see that aren't on postal routes are old beat-up ones people bought from the post office for very low dollar when they were completely worn out. Replacing one unique kind of vehicle with another on an 'as they wear out' basis shouldn't pose that many problems. I agree that on rural routes, an electric car would make less sense - but as you say, in those areas the mail carriers generally have some arrangement by which they use their own cars. Our post-lady drives a normal LHD SUV which she owns - but the post office pays for fuel, repairs and maintenance on it. One assumes they would leave those as-is and just replace the urban vehicles. A 200 mile range must be plenty since for most of the time they are driving at maybe 10mph and spending about half their time stopped - at those kinds of speeds you'd have to be driving for DAYS to hit the 200 mile range limit. SteveBaker 17:46, 6 November 2007 (UTC)
A bit off the topic, but here in the UK some mail is delivered by the milkman on his electric float. I subscribe to several magazines and they are often through my letter box by 7:00am and the postie doesn't come until about 11:00am these days. I don't know if the delivery is definitely by the milko, but I can't see the postie making two rounds. To me it makes perfect sense to combine the roles of postie & milko, and receive all of our post nice and early like we used to.--193.195.0.102 20:46, 6 November 2007 (UTC)
There are a whole pile of things that could be delivered in this way - anything that needs to be fresh or recent could be delivered in one handy trip. Sadly, here in the USA, the idea of milk delivery doesn't seem to have taken off (or maybe it did once but hasn't survived). Added to the virtual inability to buy long-life milk, this becomes a major pain for us Weetabix lovers. On the other hand, it's very convenient that the US post delivery service will pick up mail as well as deliver it. That's something the UK system could certainly benefit from. SteveBaker 22:45, 6 November 2007 (UTC)
Unfortunately, milk deliveries are a dying breed in the UK as supermarkets have undercut the traditional milkman. I don't know why the post office have never tried using battery vehicles as they'd be ideal for mail deliveries and collections. Couriers could also use them for local journeys. UPS seem to have a fleet of highly customised vehicles that are unique to them so surely they could try it? GaryReggae 23:50, 6 November 2007 (UTC)

[edit] seeing blood vessels

The doctor had a waiting room full of patients so I did not ask him this question. After he gave me medication to make the blood vessels in my eye swell as a test for diabetes I could see after he stopped shinning a light in my eye in a flash blood vessels. How is this possible? Are the receptors in my eye covered by blood vessels that I can not see unless they are swollen and if so how is this possible. Wouldn't the blood vessels still block or interfere with the light hitting the receptors? Dichotomous 10:30, 6 November 2007 (UTC)

This is an evolutionary mistake, that the blood vessels are in front of the light receptors. That is why we have a blind spot, that's where there is a cluster of them. Elsewhere they are normally thin enough that enough receptors are hit to give us an image. We aren't normally aware of this flaw in our vision because our brains "fill in the gaps" with a best guess as to what's there. However, when the blood vessels are larger than normal, the brain can't overcome this. StuRat 11:06, 6 November 2007 (UTC)
Don't call it an evolutionary mistake. There are no mistakes in evolution. Evolution is merely horribly inefficient, and not all the traits lifeforms possess are necessarily good or useful. They simply exist because the species can live long enough to reproduce despite the bad traits. 64.236.121.129 14:40, 6 November 2007 (UTC)
Please see Blind spot (vision). The blind spot is not due to blood vessels mostly due to the axons of the retinal ganglion cells (and there are also some small blood vessels passing through the optic disc). The retina has a good design because it places the photochemically active rods and cones at the back where they can shed their older photo-sensory components into the pigment epithelium. --JWSchmidt 15:07, 6 November 2007 (UTC)
64, calling evolution inefficient has the same basic problem as calling something an evolutionary mistake: they both imply that it's actually trying to do something, rather than something that just happens. — Daniel 01:12, 7 November 2007 (UTC)
Any phrasing seems to imply intention. Fault, error, mistake. The way eyes work is one of many unfortunate ways the human body works. Good design? Not a design, also ours is not the best way eyes work. Birds have much better eyes than us. Also, there's one part of our eyes which isn't obscured by blood vessels, and that's the only bit that does any worthwhile seeing (yeah, okay, the low quality stuff that our eyes also do is worthwhile too) - that three-dee panoramic full colour view most of us think we see is more of an illusion than anything else, at any moment, you can only see in detail an area about the size of the full moon as seen from Earth. See saccade for more info on how that works. Also have a look at change blindness. --Psud 09:23, 7 November 2007 (UTC) (my comments edited at 09:37, 7 November 2007 (UTC))

[edit] Astronomy, living far north

Hi, I tried to search Wikipedia for some material on celestial navigation. I currently live at a latitude of about 71deg north, and thus am experiencing complete darkness for about three months now. While it would be nice to acquire a stargazing map that details what I see (from northern Norway) at roughly midnight (first request), it would also be nice to have one that detailed what I see at noon (second!). Not that it is dark enough at noon that I can see most stars, but I imagine I can make the two maps 'overlap' in such a manner that I can follow celestial objects beyond simply those that can be seen at night.

If you can help me out with this, thanks in advance. :) 213.161.190.228 11:09, 6 November 2007 (UTC)

This thing is great. It's made for 40 north, but you could cut it for your horizon. That combined with a real star atlas like Sky Atlas 2000.0 or Becvar's Atlas of the Heavens should get you there. --Milkbreath 12:32, 6 November 2007 (UTC)
Of course one of the problems with living that far north is that your view of the sky doesn't change all that much depending on time of day. If you live on the equator, you get a total view of the entire sky over 24 hours (except, of course the sun rises and blots out half of it) - if you live at the poles, then the planet is essentially just spinning you on the spot so the sky seems to spin - but no new stars appear through your long night. At your latitude, the sky is going to "wobble" but there will be less difference between noon and midnight than at more equatorial latitudes. My imagination tells me that some of the stars nearest to the horizon at noon probably going to be obscured by sky glow because the sun is only just below the horizon - but I don't know for sure - a lot depends on how clear the atmosphere is where you live. SteveBaker 12:46, 6 November 2007 (UTC)
There are a lot of options for generating a view of your night sky. Sky and Telescope magazine has an online interactive sky chart applet: [3]. Starry Night (planetarium software) has (or had, the last time I checked) a downloadable free version that had stars down to fifth or sixth magnitude. Some fully-featured free options include Stellarium and Celestia. I can't comment on the suitability for printing of the output from any of the applications I've listed, but all will allow you to view the sky at an arbitrary time of day from an arbitrary location on Earth; they will also allow you to run the clock back and forth so you can see the 'wobble' that SteveBaker describes. TenOfAllTrades(talk) 13:20, 6 November 2007 (UTC)
Actually, I know a better link. It's the longitude for Oslo plus the Latitude for your location. Now, scroll down, and select "universal time", and replace the xx:xx:xx time with 23:00:00 for midnight and 11:00:00 for noon. It does not require any download, and probably doesn't need java either. Remember results might not be accurate completely. It's also better because you can scelect the coordinates exactly. Hope this helps. Thanks. ~AH1(TCU) 01:26, 8 November 2007 (UTC)

[edit] space diamonds

What exactly are space diamonds? Are they physically identical to diamonds found on earth? How are they collected? Where are they distributed? How do you verify their origin? How do they compare in price? What do existing diamond suppliers think about space diamonds? Etc..., I'm curious. —Preceding unsigned comment added by Mangosunshine (talk • contribs) 14:58, 6 November 2007 (UTC)

Presumably this means stellar and/or planetary cores that have been compressed into diamond. They're an interesting find astronomically and have no impact whatsoever on the diamond market. — Lomn 15:18, 6 November 2007 (UTC)
Carbonado or "black" diamonds may have an extraterrestrial origin, according to some researchers. And the core of white dwarf BPM 37093 is thought to be crystallised carbon, which you might loosely call diamond - so it has been nicknamed Lucy (after Lucy in the Sky with Diamonds) - but BPM 37093 is 50 light years away. You can even buy Space Diamond Gift Certificates, but I suspect they are nothing more than rather expensive pieces of paper. Gandalf61 16:09, 6 November 2007 (UTC)
Wow. "Here you go darling, it's all that is left from an entire star compressed into a diamond." Keria 16:58, 6 November 2007 (UTC)
There have been many speculations about various planetary cores being mainly carbon (that's part of the plot of the one of the sequels to "2001: A Space Odyssey (novel)" - I think it was 2061: Odyssey Three....mmmm...yes, that was it) - and at those temperatures and pressures, that would make a diamond of impressive size. Really, diamond isn't all that rare or special. We can now make synthetic diamonds that are better quality than "the real thing" - and which have to have artificial impurities introduced to them to make them look more real. The only reason diamonds are as expensive as they are is because the De-Beer folks make them so by hoarding them and only letting them out in quantities they control. It's a nasty monopoly. There is no doubt that diamonds should be commonplace and as cheap or cheaper than cubic zirconium. Another way that diamonds may become common is via nanotechnology - it's often said that if we had nano-bots going around making stuff for us, probably the easiest material for them to make would be diamond. Since the stuff is amazingly hard and could be made utterly smooth, we might one day find that many large-scale structures are most efficiently made from diamond. At this point, the value of diamond will be no more than a piece of coal. The same thing would happen if a large chunk of diamond were to be hauled in from space or impact on the earth as a meteorite. SteveBaker 17:31, 6 November 2007 (UTC)

[edit] Can chewing your lips cause cancer?

My dentist once told me that if you chew your lips (like chew the chapped, dried parts off), it can cause cancer. Is this true? 64.236.121.129 15:06, 6 November 2007 (UTC)

!!!THIS IS NOT A MEDICAL DIAGNOSIS!!! - Some users feel it is necessary to delete any and all mentions of medical information because they perceive it as being a medical diagnosis. This is in no way a diagnosis. It is a note on medical studies that have been done on the topic asked about.
See leukoplakia. Some studies have linked chewing on the lips or inside of the cheeks with leukoplakia and other studies have identified leukoplakia as a precancerous condition. Put together, that means that a very small number of studies have linked chewing on your lips to cancer in a rather roundabout way. This comes down to the definition of "can". Does it mean "it is likely to cause cancer" or "it is possible in a very rare circumstance that it will cause cancer"? -- kainaw™ 15:46, 6 November 2007 (UTC)
Thanks for the notification, I appreciate that. I've found that most people tend to chew on their lips because they become chapped. What causes chapped lips? 64.236.121.129 15:54, 6 November 2007 (UTC)
See chapped lips. -- kainaw™ 15:57, 6 November 2007 (UTC)
Err, that article is pathetically bad dude... 64.236.121.129 16:05, 6 November 2007 (UTC)

When the mucous membranes of the lips become dry they both become brittle and shrink resulting in superficial cracks. This is chapped lips. Dehydration and wind are two common mechanisms for the drying out. 83.147.141.69 19:49, 6 November 2007 (UTC)

[edit] Selection of yeast by growth media

I grew yeast which contained a vector coding for Leu and Trp allowing them to grow on media lacking leucine and tryptophan. However, when grown on media -Ura-Leu-Trp how come the yeast were able to grow, Ura was not coded for? Any ideas would really help...

--67.71.12.246 18:54, 6 November 2007 (UTC)Cat

I'm not sure, but first you know that Ura is not an amino acid, as are Leu and Trp, but rather a pyrimidine. Uracil can be synthesized by the hydrolysis of Cytosine, (see Uracil#Synthesis). Hope that helps. (EhJJ) 21:05, 6 November 2007 (UTC)
Hum okay...still not sure though...i had completely forgotten though that uracil was not an amino acid (rather a nucleic acid) but thanks for reminding me of that...but like then why do we have to exclude it from the medium...I'm not getting the reasoning behind it...

--67.71.12.246 21:38, 6 November 2007 (UTC)Cat

Maybe the reason was to confirm that they can make their own uracil? A lot of classroom science experiments don't make any sense at all. Someguy1221 22:49, 6 November 2007 (UTC)
Yeah I thought about that too...hehe but I figured there must be some point to it (guess I won't mention it in my lab report like that there's no chance of getting it wrong) i just would like to understand the point...because it's been playing with my mind for like 3 days!

--67.71.12.246 23:04, 6 November 2007 (UTC)CAT

You have to remember that wildtype yeast can grow perfectly well in very minimal media. That is, if you plate most wildtype yeast strains onto -Ura -Leu -Trp media, you'll get colonies. What yeast researchers have done is isolated yeast auxotrophs which require Ura, Leu & Trp supplementation. These strains are each deficient in a single enzyme in the biosynthetic pathway for their respective compounds (separate enzymes for each pathway). Since they can't make it themselves, they have to get it from the media. This allows you to introduce plasmids encoding the deficient gene as a selectable marker. If the cells don't have the plasmid, they don't have the gene, can't make the compound, and can't get it from the media, so they die. If they have the plasmid, they can replace their deficient enzyme with the one on the vector, make the compound, and grow colonies. All of this is predicated on transforming the vector into a yeast strain which is a Ura/Leu/Trp auxotroph. My guess is that the yeast strain you used was *not* a Ura auxotroph ... that wouldn't explain why you didn't just use -Leu -Trp media instead, though. -- 22:18, 7 November 2007 (UTC) —Preceding unsigned comment added by 128.104.112.105 (talk)

[edit] Axial muscles

Probably a very simple question for many of you: what are axial muscles?
(I've checked muscle but axial muscles isn't mentioned there, and I checked Wiktionary, which says: axial = "Belonging to the axis of the body; as, the axial skeleton; or to the axis of any appendage or organ; as, the axial bones" - but I still don't understand which muscles are meant by axial muscles.) Lova Falk 19:30, 6 November 2007 (UTC)

It means the skeletal muscles on the trunk of the body or the head - basically excluding the limbs and non-skeletal muscles. -- kainaw™ 19:37, 6 November 2007 (UTC)
Thank you! Lova Falk 20:17, 6 November 2007 (UTC)

[edit] Why do we call alcohol, ethanol when talking about fuel?

Umm, it's the same thing. So why the different name? 64.236.121.129 19:47, 6 November 2007 (UTC)

See alcohol and ethanol. They are not the "same thing". -- kainaw™ 19:50, 6 November 2007 (UTC)
Yea but, ethanol is the alcohol found in alcoholic drinks. When people say alcohol, they refer to that. 64.236.121.129 20:08, 6 November 2007 (UTC)
When people "who are ordering a beverage" say alcohol, they are referring to ethanol. The most common use of "alcohol" where I work is a reference to methanol. I wouldn't call alcohol and methanol the same thing simply because of my subjective experience at work. -- kainaw™ 20:12, 6 November 2007 (UTC)
And if you drink fuel ethanol, you may get very sick (or even die) because it has impurities (such as methanol) that are not safe for human consumption. Fuel ethanol and drinking alcohol are not interchangable. Dragons flight 20:14, 6 November 2007 (UTC)
Wait a minute, if the fuel ethanol also has other alcohols like methanol, shouldn't we call it alcohol anyway because it contains more than one alcohol, and not ethanol exclusively. Ethanol powered cars should be called alcohol powered cars because there's more than one alcohol in the mixture. 64.236.121.129 20:20, 6 November 2007 (UTC)
That's like saying we shouldn't call the stuff I put in my tractor "diesel fuel", because it also contains a red dye. The other alcohols are impurities that are present in small quantities, not essential components of the fuel. You still call the stuff that comes out of your faucet "water" even though there's minerals and maybe fluoride in it, right? -- Coneslayer 20:30, 6 November 2007 (UTC)
Those are bad analogies dude. Diesel fuel and red dye don't have a general term to refer to both of them. Where as, both ethanol and methanol are alcohols. Hmm if methanol is not an essential component, I guess that makes sense though, but why would impurities like methanol exist in ethanol. You don't accidentally get methanol in your beer. If you did, you'd be dead. 64.236.121.129 20:38, 6 November 2007 (UTC)
My guess would be that it's a difference between fermentation by yeast, and industrial processes for producing ethanol. But if you're making an argument that we should use "alcohol" instead of "ethanol", you should give us a good reason for doing so. There is already an excellent reason for using "ethanol": there are other alcohols that are used as vehicle fuels, and you can't use ethanol in an engine that's designed to run on methanol, or vice-versa. Thus, using the precise name is advantageous. What would be the advantage of saying "alcohol" instead, as you suggest? -- Coneslayer 20:44, 6 November 2007 (UTC)
So then why not ferment the ethanol by yeast instead of the industrial processes? No argument dude. Those are fine reasons to call it ethanol. 64.236.121.129 20:50, 6 November 2007 (UTC)
Actually, I stand corrected--according to Ethanol, a lot of the fuel ethanol is produced by fermentation. The toxic components may be introduced deliberately for denaturing. There may also be toxic components besides the alcohols, such as detergents. -- Coneslayer 21:00, 6 November 2007 (UTC)
Yeasts etc make a variety of alcohols, the main one's ethanol, but methanol's in there in noticeable amounts too. Actually, there's a bit of effort put into removing methanol from the drinking stuff when it's distilled, they wouldn't bother with that for fuel or industrial use. Actually, I note that nothing's done to remove other alcohols from beer either. --Psud 09:03, 7 November 2007 (UTC)
Wow, I can't believe they will make that stuff toxic on purpose just to avoid taxes. 64.236.121.129 21:05, 6 November 2007 (UTC)
It doesn't matter how toxic it is, because it's not intended for human consumption. Seems like a pretty obvious business decision: don't pay more than you have to. DMacks 21:55, 6 November 2007 (UTC)
NO! REELY?! We know ethanol fuel is not for human consumption dude. Don't waste time pointing out obvious facts. 64.236.121.129 14:24, 7 November 2007 (UTC)
In that case, why are you feigning astonishment about how toxic a non-foodstuff is ("Wow, I can't believe they will make that stuff toxic on purpose just to avoid taxes.")? DMacks 17:06, 7 November 2007 (UTC)
LOL! That's this kid's M.O: Ask a perfectly valid "why" question, then slam everyone who answers because he either doesnt understand, or doesnt want to hear that answer. Ok, here's the real reason we don't mix the terminology between Ethanol and Alcohol: Because the Battle Mechs with the spherical wheels, that fly using ducted fans over to drain Loch Ness in order to see if a parisitic twin got cancer from biting its lip would rather use Ethanol as an alternative to gasoline. You rock kid... don't ever lose your imagination! :) (But don't bite the folks who try to get to the bottom of your "whys" either). :) —Preceding unsigned comment added by 198.172.206.151 (talk) 19:12, 7 November 2007 (UTC)
Whoever's alt account is 198.172, you are cracking me up with trying to hide behind an ip so you can flame and not be given a scarlet letter on your real account. Haha. I can take 3 guesses as to who you really are. 64.236.121.129 21:22, 7 November 2007 (UTC)

Alcohol is a chemical family. Ethanol is a type of alcohol, referred to as "alcohol" because it is the most common type encountered. —Preceding unsigned comment added by 83.147.141.69 (talk) 19:53, 6 November 2007 (UTC)

In other words, ethanol is a type of alcohol, but not all alcohol is ethanol. So maybe your question might have been - Why do we not talk about drinking ethanol rather than the more general term alcohol? Why don't we have Ethanolics Anonymous? -- JackofOz 20:18, 6 November 2007 (UTC)
Exactly. And it's sometimes clear from context- as pointed out above, if people are talking beverages, it's clear that alcohol means ethanol. When you're talking about industrial usage, it's less clear so people tend to use more specific terms. Friday (talk) 20:22, 6 November 2007 (UTC)
Yeah - there are lots of kinds of alcohol. Ethanol is one of them, Methanol is another. When you are talking about fuels, the word "alcohol" has considerable ambiguity - did you mean methanol or ethanol or butanol or pentanol or 2-methylbutanol or...? When you are talking about things people drink however, there is no ambiguity because the only alcohol that's even close to being safe to drink is ethanol - so when we talk about alcoholic drinks - we're always talking about ethanolic drinks and there is no ambiguity worth mentioning. Language is sloppy - and when a laymans term intersects with a scientific term, it's never a good thing. Do you use the brakes and steering wheel on your car to accellerate it? In scientific terms 'accellerate' means 'change velocity' - so the answer is yes - both steering and brakes accellerate your car. Messy! SteveBaker 20:23, 6 November 2007 (UTC)

So while it's certainly true that the word ethanol is more specific than the word alcohol, I wouldn't take it for granted that that's the reason the E-word is used at the pumps. These naming decisions are made by marketing people, legal departments, and bureaucrats, more than by scientists and engineers. They may have been worried that, if they called it "alcohol", someone would try to drink it. --Trovatore 21:04, 6 November 2007 (UTC)

I agree - that would certainly have been a risk. Even E85 ethanol (which is 85% ethanol) would be suicidally dangerous to drink - the E10 stuff we have now would be much, much worse! If we ever start to use E100 (as they do in Brazil) I dare not imagine what might happen! 70.116.10.189 22:11, 6 November 2007 (UTC)
Is there a typo there? How could 10% be much, much worse than 85%? -- JackofOz 22:17, 6 November 2007 (UTC)
Because the other 90% is gasoline! 70.116.10.189 22:22, 6 November 2007 (UTC)
I must be a little slow this morning; would you indulge me as I try to get this straight? E10 is dangerous, mainly due to the 90% gasoline content. E85 is dangerous, mainly due to the 85% ethanol content. E100 is dangerous, because it is pure ethanol. Is that it? -- JackofOz 23:01, 7 November 2007 (UTC)
E10 is dangerous, mainly due to the 90% gasoline content. E85 is dangerous, mainly due to the 15% gasoline content. E100 would be dangerous, because it's intentionally denatured (made toxic), so that it can't be used as a beverage—but idiots might think it's safe because it's called "100% ethanol". -- Coneslayer 23:11, 7 November 2007 (UTC)
Well, 100% ethanol is not exactly "safe". It will seriously irritate your mucous membranes, certainly enough to be painful and possibly enough to be dangerous. --Trovatore 03:01, 8 November 2007 (UTC)

You might try Alcohol#Etymology; the word "alcohol" certainly predates the word "ethanol". shoy (words words) 20:42, 7 November 2007 (UTC)

Did you know? In Brazil, both the beverage and the fuel ethanol are just called "alcohol". We can even say something like "to increase the percentage of ethanol in the alcohol fuel" 200.255.9.38 13:23, 12 November 2007 (UTC)

[edit] If we can drain lakes, why don't we drain Loch Ness to see if the Loch Ness Monster is there

Why not? 64.236.121.129 20:28, 6 November 2007 (UTC)

Why bother? Who cares? If they that do can raise the money, overcome environmental and other concerns, figure out what to do with the water, and get the necessary permits, I say go for it. DMacks 20:38, 6 November 2007 (UTC)
Lots of people care dude. Lots of people care. 64.236.121.129 20:40, 6 November 2007 (UTC)
Loch Ness is very deep (>230m) and it would be very difficult to drain. Besides, as the water level dropped, Nessie would simply entomb herself in the solid rock in the same way a toad can and avoid detection.--193.195.0.102 20:51, 6 November 2007 (UTC)
If the monster exists, it probably needs the lake. Drain the lake and kill the monster, meaning the monster would not exist. Might as well just declare the monster does not exist. Then we can skip draining the lake. Johntex\talk 20:53, 6 November 2007 (UTC)
What's to say that they (c'mon, if there is something down there, there'll have to be a breeding population of them - it's an unknown animal, if anything, not an immortal 'magical beast') even spend all their time in the loch? --Kurt Shaped Box 21:46, 6 November 2007 (UTC)
These questions have been asked many times in the past. Any serious debate is over. We have all the proof we need to know there is nothing there. The entry and exit to the Loch are fairly shallow streams and go through well populated areas. Nothing of any size could get up and down there without being very visible indeed. For a breeding population of any species to survive, you need at least 500 individuals in order to have enough genetic diversity. 500 creatures the size of the hypothetical Nessie could just maybe hide in the Loch (although how they'd have avoided being found in sonar studies and other careful searching is hard to imagine) - but the effect they'd have on the local fish populations would definitely have been noticed. So, no Nessie. Sorry - it's just not possible. 70.116.10.189 22:21, 6 November 2007 (UTC)
Why don't we cut down the rainforest to see if there are any endangered species there...? TenOfAllTrades(talk) 22:08, 6 November 2007 (UTC)
Because that would destroy the rainforest! DUH! Man... Think a little man, it's not that hard to figure out :). 64.236.121.129 14:32, 7 November 2007 (UTC)
I think you missed the sarcasm. I guess the point is, if you remove the creature's living environment (loch ness or rainforest) then whatever you do find is kind of screwed. Besides, the mystery is 99% of the fun with Nessie! :) ArakunemTalk 18:19, 7 November 2007 (UTC)
He was being sarcastic?! NO! REELY?! I just like to crush pathetic attempts at smart assery :). 64.236.121.129 21:25, 7 November 2007 (UTC)
An excellent idea, think of all the Bigfoots we could find! -- MacAddct  1984 (talk • contribs) 23:15, 6 November 2007 (UTC)
Ohhhh - I was assuming we'd be training them to wield the chainsaws. OK, nevermind. SteveBaker 03:25, 7 November 2007 (UTC)

[edit] Diaphragm

Is Diaphragm a smooth muscle??thanks--82.105.205.27 21:17, 6 November 2007 (UTC)14mala

No. It is striated, and is under voluntary control. Make yourself cough! Voila! :-) Fribbler 21:24, 6 November 2007 (UTC)

[edit] Nuclear Ingredients

i am unable to find out (as a list) all the ingredients to a nuclear bomb this is for my physics homework. i would really appreciate if you could help in any way. i have been through all of the wikipedia nuclear articles but i am not successful. please can you help me. all the information that i have gathered about nuclear ingredients were plutonium and uranium. thank you very much —Preceding unsigned comment added by 87.74.98.190 (talk) 21:21, 6 November 2007 (UTC)

Ahmadinejad? Is this you? —Preceding unsigned comment added by Fribbler (talk • contribs) 21:25, 6 November 2007 (UTC)
You might be having problems because you expect the recipe to be more complex than it is. Really, you just take some plutonium and use conventional explosives to squish it. The ingredient list gets bigger if you want to increase yield, but in general nuclear explosions are pretty simple compared to chemical explosions. It has more to do with the technique of the chef than the recipe. --Mdwyer 21:42, 6 November 2007 (UTC)
This article will give you step-by-step instructions for a fission device. Delmlsfan 21:54, 6 November 2007 (UTC)
The abstract principle of a fission weapon is very simple. You need to take several chunks of radioactive material (plutonium or uranium) that are each, individually, much less than the critical mass for that substance - and you need to slam them together into one large chunk that's bigger than the critical mass so it goes bang. Everything else is annoying engineering details.
The most significant problem is that if you just take two half-critical mass chunks and push them together with a lever or something - they'll get so amazingly hot that they'll melt and distort so much that you won't be able to get them close enough together and the thing will 'fizzle' - make a horrible radioactive mess - but not much of an explosion. So the next trick is to slam them together using high explosives so they move so fast that they don't have time to heat up an fizzle. But now you have to set off those explosives at precisely the same moment and have them slam the pieces together just right - or no bang. Then the components of the bomb have to be assembled in such a way that the person putting them together doesn't die of radiation poisoning and they have to be in a chunky enough bomb casing that the finished device can be handled safely. These weapons aren't cheap and you certainly can't afford to have one not go off when you want it to - or go off when you don't - so the fuses and timers and other precautions are much greater than with a regular bomb. You can't use normal computers and such inside the bomb because the radiation can corrupt their memories.
The whole very simple idea just turns into a gigantic pain in the ass when you try to actually build one. SteveBaker 22:34, 6 November 2007 (UTC)
Eh, you've made things more complicated than you need to. You don't need computers inside a gun-type bomb. You don't even need to have well-timed explosives—just send one of the sub-critical bits into another, don't have them slam together simultaneous, that just complicates things. You're confusing the gun-type weapon—which is really quite simple—with the plutonium bomb—which is not. The finished device—which in a very primitive bomb is going to be quite large—is not going to be terribly radioactive as long as you keep the two sub-critical bits properly apart from each other at all times. The hardest part here is going to be getting enough high-enriched uranium; the design could be done by someone with the engineering knowledge of repairing motorbikes. You only need more sophisticated knowledge if you want to say, drop it out of a plane, which requires being able to fit a lot of things into a relatively small package and make sure the wires won't come undone, etc. (A plutonium bomb is quite different and requires very sophisticated engineering on top of everything else.) --24.147.86.187 04:22, 7 November 2007 (UTC)
It should be noted for completeness, though, that there are a couple of significant tradeoffs with the Little Boy design. One, you have to use uranium. Plutonium won't work. Two, you need (relatively speaking) a lot of uranium -- over 60kg vs less than 5kg plutonium in an implosion-type bomb. — Lomn 05:49, 7 November 2007 (UTC)
True enough. It's actually a great blessing that from an engineering and physics perspective these things are balanced as they are—uranium is easy to make a bomb with, but hard to produce; plutonium is easy to produce, but hard to make a bomb with. It might not be too hyperbolic to say that these simple facts have done more for non-proliferation than anything else out there. --24.147.86.187 15:11, 7 November 2007 (UTC)
The article Nuclear weapon design is pretty thorough. There are more ingredients mentioned there than you have. What about the trigger? Give it a read. --Milkbreath 22:53, 6 November 2007 (UTC)
For an even more simple assessment, see the pages on the first two atomic bombs: Little Boy and Fat Man. They have pretty straightforward "ingredient" lists, blueprints, etc. The hard part is not the design, for the most part. The hard part is in getting the materials. --24.147.86.187 04:18, 7 November 2007 (UTC)

[edit] What's the name of that multicolored thing on TV?

It's a screen where you have several different bars, and they are all different colors, and the TV emits a high pitch noise. What is that? 64.236.121.129 21:22, 6 November 2007 (UTC)

I call it a test pattern, or "Bars and Tone". Here's a link: SMPTE color bars --Mdwyer 21:34, 6 November 2007 (UTC)
Historically, it was called a test card and was used in the early days of television to make sure the colours all looked correct. When the TV station closed for the night, the test card was broadcast although nowadays it is a rare sight. GaryReggae 23:43, 6 November 2007 (UTC)
They were broadcast during the daytime in the UK before all-day broadcasting was instituted. The idea was that TV repair shops could make use of them to figure out a range of different problems inside the TV set. These days you can cheaply buy a little box to generate a range of different TV test patterns for this purpose - so there is no need for them to be broadcast - although I believe some cable and satellite services still dedicate a channel to transmitting them. SteveBaker 03:53, 7 November 2007 (UTC)
Very rare on broadcast TV though. We've got a couple of sub-24 hour/day TV stations where I live, neither of which show a test pattern overnight. I did see a test pattern for about three seconds during a system fault a few months ago on one of our major commercial TV stations, but their standard "Sorry for the inconvenience" screen replaced it quickly. --Psud 08:44, 7 November 2007 (UTC)
In countries using the NTSC television system, such as the United States, a color bar test signal is still used as a reference to adjust analog receivers and frame synchronizers to fine tune four basic video levels to match the transmitted NTSC signal: Video level (contrast on home receivers), black level (brightness), chroma saturation (color) and chroma phase (hue or tint). Many satellite uplinks transmit this signal when the main program is not in progress, so that those users downlinking their signal can adjust their receivers.
The "high[-]pitched noise" referred to by the OP is a generally a standard audio reference tone, 1 kHz in frequency and transmitted at a standard amplitude of 0 VU. Again, this is used to adjust the level of the receiver's audio gain to match the standard level sent from the source. Thomprod 19:34, 7 November 2007 (UTC)

[edit] Could a parasitic twin lead to an evolutionary change?

I was just watching this bizzare video on CNN, http://www.cnn.com/2007/HEALTH/11/06/india.girl/index.html#cnnSTCVideo ,and I was wondering if a parasitic twin could potentially lead to a evolutionary change where an species of animal has more limbs because of failed twinning. 64.236.121.129 21:43, 6 November 2007 (UTC)

See conjoined twin for some background info. I don't think this situation is guided by genetics- it's more of a physical accident. So I don't see room for genes that cause this to be passed on. Also, this condition doesn't improve one's chances of survival and reproduction- quite the opposite. Friday (talk) 21:48, 6 November 2007 (UTC)
I agree with your first point, but your second point assumes too much. Malamockq 00:52, 7 November 2007 (UTC)
Empirically, Friday's second point is quite correct. The parasitic twin extra limb thing (as opposed to conjoined twins) is invariably detrimental to the person. In this case, various articles have noted that the child is entirely unable to walk and likely to die before adolescence without radical surgery. While we can theorize a beneficial Doc Ock-style extra limb thing, evidence suggests that such benefits are confined to the realm of fiction. — Lomn 02:29, 7 November 2007 (UTC)
Surely the key point here is Friday's first point, that the condition of having a conjoined twin/parasitic twin is not genetic. Therefore, regardless of whether it might convey any benefits to the individual concerned, it is not inherited, and so cannot play any part in the evolution of a species. Gandalf61 16:15, 7 November 2007 (UTC)

Yes that's what I thought. Just wanted to make sure. Btw lomn, I think your assumptions are based on conditions right now rather than changing circumstances in the enviroment. If a nuclear war, ice age, etc happens, there might be circumstances where many limbs would be preferable. Or not. I just think it's bad to assume things just based on current circumstances. Poor science pally boy. 64.236.121.129 21:15, 7 November 2007 (UTC)

While the possibility of changing environments is good to keep in mind (very wierd things can happen, like the loss of an appendage or sense becomes advantageous), the inability to survive adolescence is simply not beneficial. And even if she could survive without surgery, I don't see how not being able to walk is advantageous. Maybe if a strange animal appears that eats anyone with less than 8 limbs... Someguy1221 21:24, 7 November 2007 (UTC)
Dude, I wasn't talking about that girl. I was talking about a mutation where you have lots of limbs. 64.236.121.129 21:38, 7 November 2007 (UTC)

[edit] Altruistic act? I dont think so

I was having a discussion the other day about whether all acts are truly motivated by self interest, I am for the motion, and was looking to see if anyone could help me by provide some research into the area, I am particularly interested in finding a piece of research I read a while ago into how your brains distorts positions to your point of view in order to justify decisions you have previously made, which could lead to you believing acts were altruistic when they are not. Thanks. 172.200.188.149 22:02, 6 November 2007 (UTC)

I think a key problem with saying that is you need to very firmly define "motivated by self-interest." Certainly all actions beyond accidents are motivated by something and we can always contort our reasoning to call that self interest, for even if it does not benefit a person in any obvious way, there is some reason they "want" to do it. Someguy1221 22:07, 6 November 2007 (UTC)
The Principles of NLP say that Behind every behavior is a positive intention. Whether that intention is positive towards your own welfare without regard to others', or towards others without regard to your own, or some of both, would depend on the circumstances. -- JackofOz 22:15, 6 November 2007 (UTC)
While this won't help you with the second part of your question, our article here on Objectivism might be a good place to start your research on this topic, and will at least give you some food for thought about the philosophy supporting your thesis. Jeffpw 22:20, 6 November 2007 (UTC)
Maybe you were thinking of Cognitive_dissonance#Origins_and_experiment? Altruism#Altruism_in_ethology_and_evolutionary_biology has some good places to start too. -- Diletante 22:41, 6 November 2007 (UTC)

The distinction you're concerned with here is one of behavior versus motivation for that behavior. We can define altruistic behavior and then give examples of humans behaving altruistically; someone risking their own life to save a stranger's should satisfy most definitions and is certainly not unheard of. However, trying to answer the question of whether or not such behavior was selfless and disinterested true altruism and not motivated by some conscious or unconscious selfishness is problematic. To prove or disprove such a thing would require knowing the internal thoughts and motivations of the person in question, something not currently available to science. See the Criticism section of Psychological egoism for more. So, it's an unwinnable arguement for both sides from a scientific perspective. My take is that, yes, from a biological/evolutionary perspective selfishness is a hard-wired human trait, but genetic traits are not fixed or unmodifiable; humans are a very unique species and I wouldn't discount out of hand the possibility of true altruism in humans. Either way, there's worse things to aspire to than acting altruistically, regardless of true motivation. Azi Like a Fox 17:45, 7 November 2007 (UTC)

Saving a stranger raises social your standing, earns you 'brownie points' as such, also you expect people to do the same thing for you, and prolongs the survival your species. And acting altruistically is a bit of an oxymoron as something must be motivating you and if it is something else, then its is altruism and not acting, and if its selfish then its not altruistic at all. ΦΙΛ Κ 21:45, 7 November 2007 (UTC)
Right, and by the Original Poster's definition these ulterior motivations all preclude the original act of saving someone as "true" altruism. The expectation of someone doing the same for you would be reciprocal altruism (talk about an oxymoron). I was trying to explain that it's unknowable/unmeasurable whether someone's altruistic action is ever truly devoid of self-interest; given human nature it's not unreasonable to think that such actions aren't or can't be, a bit cynical but not an unrealistic position. Regardless, my point was that even if you say that no human action can be devoid of self-interest, it's still better that people behave generously and altruistically even if such behavior is motivated at some level by self-interest. My giving to local charities is none the less beneficial to the community and the recipients for being predicated on what I consider rational self-interest and an investment in the mid to long-term future rather than a disinterested and altruistic desire to be charitable. If instead I gave because it simply made me feel good to help others, then again it could be argued my motivations are self-interested (my own pleasure in helping others) rather than purely altruistic. So be it, teaching and cultivating altruistic behavior is all the more important and remarkable when it happens in light of our "selfish" nature. Hope that clears up what I mean by describing an action as altruistic even when the motivations behind it aren't always. Azi Like a Fox 23:58, 7 November 2007 (UTC)

[edit] In vitro mitochondrial respiration states

What are the different respiration states of mitochondria (1,2,3,4)?

One paper says: "In the present study, state 2 respiration is defined as the rate of respiration in the presence of substrate but before the addition of ADP." but a website says regarding state 4: "State IV respiration is defined as oxygen consumption by isolated mitochondria on a particular substrate, in the absence of ADP..." So what's the difference? --Seans Potato Business 22:44, 6 November 2007 (UTC)

I believe that the difference is that state 4 (mito + reduced substrate without ADP) is reached as a phase during the experiment after all the ADP has been converted to ATP. Whereas state 2 is a starting condition prior to ADP being added. Subtle, I know but you have to consider them with respect to phases during an experiment.
It is common to start with mito alone, state1. Then spike with substrate to get to state 2 (limited respiration will occur). Then add ATP to move into state 3 (maximal respiration) and when the ADP runs out you enter state 4. If you respike with ADP will reenter state 3 and then back to state 4 when the ADP is all converted to ATP (all assuming you have inorganic phosphate as a substrate in excess). David D. (Talk) 03:25, 7 November 2007 (UTC)
Original 1955 article & see this. In terms of the original Chance & Williams protocols, I think a typical "state 2" experiment involved plenty of ADP but no added substrate such as succinate. A "state 4" experiment involved having high levels of a substrate such as succinate while ADP was rate limiting and driven to zero concentration during the experiment by conversion to ATP. Other people define "state 2" differently. You have to look at the details of how each "state" is defined by the people doing the experiments. --JWSchmidt 03:42, 7 November 2007 (UTC)
This is an excellent point: "You have to look at the details of how each "state" is defined by the people doing the experiments". However, i might add I was going from memory and since JWSchmidt has a nice link quoting the Chance/Williams experiment that is clearly the definitive answer. David D. (Talk) 04:55, 7 November 2007 (UTC)