Wikipedia:Reference desk/Archives/Science/2007 February 8

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1 February 8

[edit] February 8

[edit] A question I can't get out of my head

Hypothetically, if all humans are incapable of feeling/experiencing pain then will we (humans) ever deduce that animals can feel pain? 211.28.131.148 11:08, 8 February 2007 (UTC)

You mean capable (not incapable) I think.

I already have deduced that animals can feel pain - when I stood on a dogs foot (by accident) the noise it made (yelp) coupled with knowledge of what I had just done made it clear that dogs can feel pain.87.102.2.204 11:32, 8 February 2007 (UTC)

Are you asking: If humans were incapable of feeling pain, would they ever deduce that animals can feel pain? The swapping of would and will makes a big difference in this case.

Humans (most of us) cannot use echolocation but we know microbats can.
Humans can only hear in the frequency range of 20 Hz to 20 kHz, whereas dogs can hear from about 16 Hz to 45 kHz and cats can hear from about 20 Hz to 64 kHz, etc.
Humans can not see infrared, but some animals can.

Of course, my examples might be different than the hypothetical situation you have proposed, since humans at least have that sense, only less sensitive. Humans can hear and know of other frequencies of sound, so it wouldn't be a great leap to deduce these things about bats, cats, and dogs. Humans can see and know of other wavelengths of light, so they could also deduce how animals can see infrared. However, it is a completely different thing to say that humans would be able to deduce that animals can feel if humans had no sense of touch whatsoever!

Just my thoughts. − Twas Now ( talk • contribs • e-mail ) 11:38, 8 February 2007 (UTC)

I don't think we would be able to deduce that animals can feel pain. However, we would be able to notice that animals had the mechanisms for feeling pain (and also realize that we didn't have them). So for example, we may be able to find pain receptors, and deduce that animals can feel something through them which we can't. However, if humans all humans are incapable of feeling pain, then the concept of "pain" would not exist in our soceity. We wouldn't understand what it was, and we wouldn't really be calling it "pain". And there the question starts getting philosophical... --`/aksha 12:06, 8 February 2007 (UTC)

Yes. Possibly we would call it thigmotaxis (or invent a name for it), seeing that animals move away from pain but without realising why (the actual feeling). It is something like how some of the animals are able to sense impending natural disasters but we humans are not able to -- WikiCheng | Talk 13:25, 8 February 2007 (UTC)

Me, I'd say that if humans were incapable of feeling pain, then no, they would never deduce that animals can feel pain, because the humans would not exist.

Pain is a vital mechanism; no animal can fail to experience it in some way. It's a tremendous survival advantage: animals which experience pain can (usually) move away from or otherwise eliminate the source of the pain before their body is fatally damaged. An animal which is in pain due to an injury can take steps to care for itself while it heals. An animal which didn't experience pain wouldn't last long.

There was a long discussion in Stephen Pinker's book How the Mind Works about whether non-humans can "feel" pain, which I thought was silly: of course they can. The only difference is that they don't call it "pain", but then, they don't usually call anything anything.

There was great line in Terminator II where John Connor asks the Terminator, "Do you feel pain?" (I think this is while the Terminator is having bullets picked out of his back.) The Terminator thinks for a moment and says, "I experience what you would call pain", which I think sums the condition up perfectly. —Steve Summit (talk) 01:32, 9 February 2007 (UTC)

Acctually I have done an experiment myself, and using an electric charge monotoring system of sorts, one is able to measure the amont of pain felt by a plant: when i inserted two probes into the stem of the plant, then broke a leaf in half it registered, therefore, we would, and can measure the pain flet by other species, plants, animals ect.

So what did you measure with your electric charge monitoring system of sorts? How much pain do you deduce that plants feel? Why would you believe that electrical currents in a plant would indicate pain? Why not pleasure? Or humor? Or dark current? --User:bmk

Scientifically, pain is separate and distinct from nociception. We can be certain animals experience the latter, but since the former is a subjective experience its open for debate whether animals "feel pain" as we do. See Pain and nociception for an overview. Rockpocket 06:56, 9 February 2007 (UTC)

Huh! "Nociception". Whouda thunkit. So my speculations above about animals (and robots) "obviously" experiencing pain were misguided, or at least underinformed.

I'm reminded of this little ditty:

There once was a thinker of zeal

Who said, "Although pain is not real

When I sit on a pin

And I puncture my skin

I dislike what I fancy I feel."

--Steve Summit (talk) 16:32, 9 February 2007 (UTC)

Well, when you cut a part of a living organism, the feeling, if at all there is one, would be of 'pain' (or agony), unless the living organism enjoys it. So the electric charge measured when a leaf is broken can be classified under pain and not under pleasure. Obviously, the plant doesn't enjoy it's leaf being cut? -- WikiCheng | Talk 08:47, 9 February 2007 (UTC)

[edit] Trichobezoar

I'd be interested to know how much (approximately since I realise there is probably no definite answer)hair would an adult have to consume in order to develop a trichobezoar which would pose some risk to their health? Thanks, if anyone has any idea.

[edit] chemistry

I need to find the chemical formulas and names and how many atoms are in the following chemicals. CH4, C2H4O2, CaCO3, NH4NO3 do you think that you can get some answers?

Well you've already given the answer to the first query: the chemical formulas are CH₄, C₂H₄O₂, CaCO₃, NH₄NO₃. − Twas Now ( talk • contribs • e-mail ) 14:20, 8 February 2007 (UTC)

CH₄

Methane
5 atoms (one C atom and four H atoms)

${CH}_4 = \underbrace{C }_1 + \underbrace{H + H + H + H}_4,$

C₂H₄O₂

Acetic acid
~~6 atoms~~ 8 atoms

CaCO₃

Calcium carbonate
5 atoms

NH₄NO₃

Ammonium nitrate
9 atoms

− Twas Now ( talk • contribs • e-mail ) 14:42, 8 February 2007 (UTC)

Molecular formulas are not very specific for organic molecules, many of which can have the same composition of atoms, but different structures. For example, glycolaldehyde is also C₂H₄O₂. --Spoon! 21:08, 8 February 2007 (UTC)

And methyl formate, methyl dioxirane, acetaldehyde oxide, and also a host of less stable isomers. DMacks 21:27, 8 February 2007 (UTC)

[edit] arun singh bagh

can I die if I lick pure diamond?

Well, it might be sharp and cut you, but otherwise no ... it's just carbon, which isn't toxic. WilyD 15:15, 8 February 2007 (UTC)

(Note I guess Arun Singh Bagh is your name - it helps if the section title relates to the question eg "Are diamonds poisonous" or something like that - most people put their name at the end of the question.)83.100.158.135 15:17, 8 February 2007 (UTC)

No. Never. Well, maybe if you lick it thousands of times until your tongue becomes swollen, causing you to asphyxiate; or after the thousands of licks, if it is cut, and you get an infection. − Twas Now ( talk • contribs • e-mail ) 15:23, 8 February 2007 (UTC)

no, as in times gone by people would lick diamond to check whether or not they were genuine, a real diamond's (as opposed to a piece of glass or other rock) surface acts much like oil and does not get wet.

I bite lick and nibble on jewels all the time and none of them are poisonus. all i know is that i can tell the diffrence between a real jewel and a fake one by licking it . (yes i guess its kinda gross but hey I get and give that peace of mind when you know you got the real deal instead of the fake plastic or glass ones) Maverick423 16:05, 8 February 2007 (UTC)

Nonsense - you will certainly die if you lick diamond. In fact you'll die anyways. We all die. (groan) --bmk

How do you know everyone will die, it hasn't happened yet:) Licking doamonds could make people live forever for some reason, but there is no proof:]HS7

Diamonds are the hardest naturally occurring things known to science. It takes another diamond to make any impact on its surface. That means you could lick one 24/7 for 50 years and you'd still never get any of its substance into your body at all. All you'd ingest is whatever dirt happened to be on its surface. As WilyD says, swallowing one whole could be a hazard, but that's nothing to do with poison. JackofOz 02:20, 9 February 2007 (UTC)

[edit] Does it snow at sea?

Many thanks, --194.176.105.40 15:51, 8 February 2007 (UTC)

Yes. (but it doesn't lay obviously)83.100.158.135 15:54, 8 February 2007 (UTC) It would be more likely to snow nearer to the poles. Apologies I haven't provided a very good answer.83.100.158.135 16:11, 8 February 2007 (UTC)

I had the opportunity to ride the Alaska Marine Highway [1] during a blizzard[2] in November 2006. Indeed it does snow at sea. Other interesting phenomenon of snow-at-sea: water retains its temperature due to its high specific heat, so the ocean (sound, bay, etc) may be several degrees warmer than the snowing air. This provides a consistent thermal updraft of air which starts at the surface of the water and flows upwards, convecting with the snowy air. This means that it is very difficult for snowflakes to actually land on the water! In fact it appears to be snowing upwards. Nimur 19:41, 8 February 2007 (UTC)

Cool! Now I want a video of this! — Kieff | Talk 22:33, 8 February 2007 (UTC)

[edit] Boric Acid

Hello

On your page about Boric Acid, it is mentioned that "boric acid can also be used as an acne treatment (see directions for solution at bottom.)"

I cannot find the "directions" for the solution and would like help or directions for this?

I hope someone can be of assistance.

Thanking anyone in advance.

Gavin

I've removed that info for now as I can't find an adequate reference - however it is true that boric acid can be used as an antiseptic - the proportions were 1 part Boric acid to 4 (boiling) water to dissolve the boric acid. I can't guarantee this is correct.

If you intend to use boric acid for this purpose - I would suggest either - following any instructions on the package OR following the instructions given to you by a pharmacist (it is usually bought at a pharmacist and a pharmacist should be able to give you instructions on it's correct use.)83.100.158.135 16:21, 8 February 2007 (UTC)

Note also that repeated use of boric acid/borates can cause poisoning - specifically when it comes in contact with a wound eg broken skin.83.100.158.135 16:23, 8 February 2007 (UTC)

It is a leftover from an old edit. Have a look at the MSDS sheet for this substance too. − Twas Now ( talk • contribs • e-mail ) 16:27, 8 February 2007 (UTC)

...like this one, courtesy of the SIRI MSDS index. Or check out the ICSC. Although the toxicology reports may be more relevant here; the MSDS and ICSC are for the concentrated stuff, and mostly just say you should be careful when handling concentrated acids (even weak ones like H₃BO₃). Just for comparison, here are the corresponding MSDS, ICSC and toxicology reports for acetic acid. —Ilmari Karonen (talk) 14:13, 9 February 2007 (UTC)

[edit] Genetics of Neurospora

Hello, When you want to calculate the distance between 2 linked genes in Neurospora Crassa, if you don't know the number of crossing-overs, when do you use the non-corrected formula (RF = 0.5*T + NPD) and when do you use the corrected one (RF = 0.5*T + 3*NPD)? Thanks in advance!! -- Max

[edit] Voltage Coefficient

Hello... Could someone pleae precisely define Voltage Coefficient??? It is a specification mentioned in data sheets of carbon filmed resisitors... Bhavikmehta2685 17:33, 8 February 2007 (UTC)

This is when a change in the physical characteristics of a component are changed somewhat due to a change in the voltage across the component. See [3] − Twas Now ( talk • contribs • e-mail ) 17:41, 8 February 2007 (UTC)

Thanks a lot Bhavikmehta2685 05:08, 9 February 2007 (UTC)

[edit] Current problem

I have a problem, I have to generate 30 Amps across a resistance of less than one milliohm. Basically, I want to find a way to convert a dc voltage to about .01 volts. I can't find a dc to dc converter that can do this. Any ideas?

Try holding one end in each hand, you might be able to produce a small amount of electricity that way:]HS7

Wouldn't you know it: DC to DC converter. -- mattb @ 2007-02-08T19:56Z

The 1 milli-ohm resistance will do almost nothing to your circuit if you add it in series to an ideal current source. You can probably create a current source which is "ideal" compared to a 1 milliohm resistance with a simple battery and resistor. I don't know if a standard lantern-battery can provide 30 amps, even at 12 volts; this is a lot of juice. But if you have a dc power supply, it should be no problem. One final question: are you sure you need to put 30 amps across 1 milliohm? This may not really be what you want, and you might smoke some components :) Nimur 19:57, 8 February 2007 (UTC)

We used to use these types of batteries (9.6 volt toy-racecar batteries) to drive current through some tinfoil - specifically for the purpose of igniting matches during science projects. You'll quite probably do the same, if you're driving 30 amps into a short circuit. Nimur 20:05, 8 February 2007 (UTC)

Perhaps I should restate everything I've said above in one sentence: your task is generating 30 Amps, then attaching that into your circuit. The voltage will appear across your resistor - you don't need to generate it. But (in dc circuits) you can't get 30 amps unless your battery can supply it... Nimur 20:13, 8 February 2007 (UTC)

what he said ^^ anyways the only other way that i can see you generating more ampage is by using conductors (the little ones that look like tiny batteries) and connect them to resistors to reduce the charge to .01 i used to do this when i made small battery powered robots so as to not fry the main processing unit but to provide enough power to the wheels and stuff.Maverick423 20:42, 8 February 2007 (UTC)

If you explain why you need to do this we may be able to advise you better. Not knowing your age or qualifications to work with electricity, I must caution you strongly against experimenting with high current (which I consider this to be) or high voltage, on the account of the danger of shock, fire, explosion, burns, or eqiuipment damage, which can occur in an instant even if you do not accidentally hook something up wrong. A qualified teacher or a qualified adult should be present and supervise all work and assure that all proper safety procedures are followed. If you or they do not know what those procedures are, then do not attempt to do the experiment and keep as a "thought experiment." I have worked out how to do it, but will reserve details until I hear more about why and how you want to do this, and what your age and qualifications are.Edison 23:00, 8 February 2007 (UTC)

Yes. Perhaps we should make it very clear that this much current can be very dangerous. Even if you are "experienced," you can burn yourself, electrocute yourself, damage your equipment, and otherwise cause harm. Nimur 00:38, 9 February 2007 (UTC)

And despite those things, the experiment can fail to be amusing. Electricity does not make exceptions for age, inexperience, misunderstanding, or give second chances.Edison 00:43, 9 February 2007 (UTC)

Hello, sorry about the delay. I am trying to create a magnetohydrodynamic pump actually, and as it turns out quite a bit of current is necessary to drive the fluid medium I desire, liquid gallium. Unfortunately, the resistance across this small gap of liquid gallium (between two graphite electrodes) is extremely small. I was hoping to find a way to shrink the voltage down considerably, but most of my ideas seem to have run into issues, as I would need such an incredible rheostat to generate this many amps. I have been considering using a car battery and a self built variable resistor from carbon rods, but as you said I'd be afraid some part of the system would smoke. I am a senior student who is working on a science fair project, and I have sought out help from a few teachers and engineers. All of whom are glad to supervise me for this project.

Eep. First of all, I would avoid using a car battery. Lead-acid batteries of that size can pack enough punch to be fatal if you screw up. Next, I think you may have hit on several of the engineering issues with a magnetohydrodynamic pump already. For something as viscous as gallium, you will probably notice that mechanical and fluid forces are significantly stronger than any electromagnetic force you can produce. This is why few (probably zero) commercial pumps operate on this principal. Danger aside, I doubt you will be able to make this thing work - magnetohydrodynamics is an advanced area of physics, so you will probably have difficulty with the theory; it also has numerous practical issues, so you will probably have difficulty with the implementation. There are many options, though!

You can come up with a complete report and theoretical diagrams of how you would build this device. Mention the practical engineering limitations (need high current, high voltage, and where in the heck will you get that much gallium! Certainly not your school's chemistry lab, I don't think it's very common in such settings! You can probably order a few ounces at exorbitant prices from science supply warehouses...$40 for 5 grams!) Talk about how all of science and engineering are fundamentally dominated by practical considerations. It is not a failure to determine something is infeasible. In fact, it would be much more of a failure to pursue something that is beyond your capacity, and then not deliver it.
You can also try switching to some other similar experiment- such as an electric ion pump. You can use this technique to dissociate ions in solution (i.e. extract sodium and chloride from salt water). This will be an interesting chemical reaction and you can discuss a lot of the science behind it. Or you could try to build a simpler mechanical pump. You can discuss the difference between a rotary pump and an internal combustion engine. You can discuss practical uses of these pumps, and explore why few applications rely on magnetohydrodynamic pumps.

Hope this helps, Nimur 02:10, 9 February 2007 (UTC)

MHD principles are a lot more frequently applied on micro scales, such as in MEMS (and in some theoretical applications, but that's not my area). The high magnetic field density required makes this a non trivial effort on the macro scale. I also wouldn't bother with the wikipedia article on MHD. It's poorly written, has poor topical coverage, is vague, etc. All you need for a simple MHD pump is a conductive fluid and a sufficiently large magnetic field. If you've really set your heart on an MHD pump, at least change the fluid you're attempting to flow to something that will make your construction job easier rather than harder.

Also, I must respectfully point out to the above poster that a car battery is not likely to kill you unless you drink its contents or allow it to fall off a ladder onto your head. In addition, I think there may be some confusion as to the nature of an MHD device, since one need know nothing more than the Lorentz force equation and basic math to understand how it works. Plasma physics only apply if you're trying to manipulate a plasma, which doesn't seem to be the intention here. -- mattb @ 2007-02-09T03:13Z

Better to err on the side of caution :) Anyway, I've only ever seen MHD applied in two areas: stellar physics, and fusion reactions. I've never to MEMS or pumps or anything else. Are you sure you don't mean Microfluidics? Those tend to make use of electric fields for moving around microdroplets of water or chemical, but I've never heard of them using magnetics. 171.64.91.48 05:16, 9 February 2007 (UTC)

I meant what I said. Electrostatics are much more common, but MHD has been used as well. -- mattb @ 2007-02-09T05:40Z

OK, To cause 30 amps to flow across .001 ohms requires that you supply a voltage of .03 volts, from E=IR. This will dissipate 0.9 watts in the .001 ohm resistance, from P=EI. A 6 volt lantern battery cannot supply this much current, nor can D cell flashlight battery. It is practically a dead short. For a test circuit, what physical form might your .001 ohm resistance take? From American wire gauge, the resistance of number 10 copper wire (the smallest size usually rated to carry 30 amperes) is .9989 ohms per thousand feet, so 1.001 foot of the wire will have the desired resistance of .001 ohms. You will find that the contact resistance between the battery or other source and the wire will greatly increase this resistance. I find that the leads of my digital multimeter have about .2 ohms resistance, for example. To measure the current you may connect a voltmeter across the approximately 1 foot of number 10 wire, and then use Ohm's Law again, but in the form I=E/R. where R=.001 ohm. If you had a battery capable of producing more than 30 amps, such as a 12 volt car battery. you MUST NOT just connect the 1 foot of number 10 wire across the battery, because that would be a short circuit. It would draw far more than 30 amps (perhaps hundreds of amps) and might cause the battery to explode or the wire to heat up red hot. If the battery produces 12 volts exactly and you wanted to reduce the current to 30 amps, you must have a dropping resistor in series with your .001 ohm resistor, to drop the voltage from 12 volts to .03 volts. This works out by Ohm's law to (11.97 volts)/(30 amperes)= .399 ohms. Even if your MHD cell were shorted, with the stated dropping resistor, the current would not increase much. It is acting something like a current source. Again from the wire table article, for number 10 copper wire, this equals (1000 feet) times(.399/.9989)=399.4 feet of number 10 copper wire, or an equivalent resistor. The power dissipated in the dropping resistor will be 30 squared times the resistance or 359 watts, so such a resistor would be very hard to find, and the wire will heat up, so the current should be only briefly applied. The car battery would discharge, and the car alternator would be overloaded, if this current drain were sustained. So in the case cited, an improvised dropping resistor could be the stated amount of number 10 wire. You could measure the current with an ammeter in series, or with a voltmeter across the dropping resistor and use Ohm's law. A second way would be to use a stepdown transformer which steps down the household voltage (such as 120 or 240 depending on your location) to a high current at a low voltage. An electric welder has this characteristic. Some arc welders produce DC output, although it will be pulsating rather than smoothed DC. Others produce low voltage high current AC, which could be rectified with diodes to produce DC. A filter might be used to smooth the ripple, with capacitive filtering. You of course must assume all risk in such experiments. [4] discusses a home-made arc welder, starting with a transformer of the required KVA and replacing the original secondary with a low voltage-high amperage secondary of one or a few turns. This would also require high amperage rectifiers and capacitive filters to produce smooth DC, and would also have all the risks associated with experimenting with electricity, such as death, injury, or property damage. Edison 05:18, 9 February 2007 (UTC)

If I were doing this "professionally", I would do what someone suggested above: Consider operating a switching regulator as an "ideal current source". It would be pretty efficient, compact, and safe. But such parts aren't readily available to be bought "off the shelf".

So for a science fair, I'd take a different approach. I'd probably take a car battery and mount it safely in an insulating container along with five or six automotive headlamps. I'd wire the headlamps in parallel and connect one end of that parallel circuit securely and safely to the battery. I'd provide heavy wire leads from the other end of the battery and the other end of the headlamp circuit. Then, when you connect those external leads together, you'll get a lot of light and about 30 amps of current flowing in the circuit. The exact resistance of the external part of the circuit won't matter much because the lamps are safely limiting the flow of current. The circuit is also limited to 12 volts (the open-circuit voltage of the battery). Packaged up nicely (with no external access to the junction between the battery and the lamps), the device would be quite safe. You could add a circuit breaker as protection and to provide a convenient on/off switch.

Two notes:

Incandescent light bulbs have very low resistance when the filaments are cold, perhaps 1/10 of the resistance they have when the filaments are hot. So my proposed circuit will put out a brief pulse of much higher current. This probably doesn't matter (and might help get the gallium moving), but please be aware of that effect and consider it.

The circuit breaker probably wouldn't be rated to break DC and so it probably wouldn't last a huge number of operations, but it would probably be fine for "science project" duty.

Atlant 13:56, 9 February 2007 (UTC)

- I have used a car battery and the car headlamp as a limiting resistor to supply fairly high current for testing purposes, but of course if you make your conections incorrectly or simply have bad luck the results could be equipment damage or personal injury. I did not note previously that if your test device (MHD cell) developed high resistance, then the full supply voltage, such as 12 volts DC, would be applied across it until it conducted the specified 30 amperes. Edison 05:19, 13 February 2007 (UTC)

[edit] Purpose of a manned space flight program ...?

Given the fact that if you could cram 200 people onboard a space shuttle and thereby limit the number of space shuttles required to put the Earth's population into Earth orbit to 32,875,406 in the event a wayward asteroid headed this way what is the purpose of a manned space flight program besides the E-ticket ride? 71.100.10.48 21:19, 8 February 2007 (UTC)

I'm not sure what the question is. There are not 33 million shuttles, nor will there ever be. By the time such an event will happen, who knows how many people will live on Earth? Even if there were 33 million shuttles, that would not be enough, since you would also need to fit enough food, oxygen, and fuel, and you would have to figure out the logistics of rallying billions of people into all of the shuttles. − Twas Now ( talk • contribs • e-mail ) 23:02, 8 February 2007 (UTC)

The chance that if life on earth was to end the possability that it can still exist elsewhere Maverick423 22:49, 8 February 2007 (UTC)

To quote Sam Seaborn: "‘Cause it’s next. For we came out of the cave, and we looked over the hill, and we saw fire. And we crossed the ocean, and we pioneered the West, and we took to the sky. The history of man is hung on the timeline of exploration, and this is what’s next." - Akamad 23:05, 8 February 2007 (UTC)

Or to quote Arthur C. Clarke who was quoting Konstantin Tsiolkovsky, "The earth is the cradle of humankind, but one cannot live in the cradle forever." --81.230.70.70 00:05, 9 February 2007 (UTC)

The purpose of the manned space flight program is because there are some tasks which are best performed by humans (as opposed to robots, computers, or anything else you might put in space). The purpose of a space program, in general, is many-fold, and includes science, politics, exploration, and many other details. I don't think it's correct to say that any present-day manned space program exists with the intent to "save our population" or "colonize other worlds." Perhaps you can take a look at NASA's Strategic Mission objectives from 2006: [5], which clearly explains exactly why we have a manned space program in the United States. (I mean, in all truth - the buck stops here. This report is what is given to federal government decision makers to explain why we have a space program, and why it should be funded). Nimur 00:43, 9 February 2007 (UTC)

Here's my cynical summary (for those who don't want to read all 44 pages:)

Kill space-shuttle program within four years
Kill the funding for International Space Station as soon as we've met our contractual obligations
Focus on ground-based science, which is cheaper
Introduce a new space transportation system with no long-term commitment (per-mission funding)
Outsource as much as possible to private contractors
Initiate a hypothetical and entirely implausible moon exploration directive which will veil the previous objectives until the space program deteriorates beyond a salvageable enterprise.

But, this is just my opinion. You should read the report yourself. Nimur 01:09, 9 February 2007 (UTC)

The purpose of the manned space program was, originally, to prove that we had a bigger dick than the Rooskies. Now, it is primarily a corporate welfare program operated to transfer American tax dollars to a small set of investors in the military-industrial complex. Nearly everything we do through manned "exploration" could be done by our robots at a much lower cost.

Atlant 14:07, 9 February 2007 (UTC)

What about in the case of nuclear war? Wouldn't a manned space flight program at least prepare Americans for orbital evacuation? That would only require 1,492,221.07 space shuttle flights at 200 Americans per trip... and who needs food? They could dine on each other. 71.100.10.48 17:23, 9 February 2007 (UTC)

- - That approach worked for the Donner party, but they did not have to worry about the oxygen supply or the carbon monoxide buildup. How big of a solar greenhouse would be required per person to convert co2 back into oxygen and to supply food?Edison 05:22, 13 February 2007 (UTC)

i think the manned space program is less concerned about immediate evacuation in event of man-made or natural catastrophe as it is geared to eventual branching out from this planet. so the likelihood of 33 million shuttles is slim to say the least...some other transport method or combo would be devised for a mass escape anyways...(PS its only going to be those less than a certain age if it happens)...the point is getting some of the younger population off the planet to new ones...and there are dozens of other reasons as mentioned above, and its a shame if we are giving up now, yet the fact is things like earthly wars cost a bunch and things like manned space programs are the first to get axed...700 billion dollar aid package to NASA???...pipe dream...(maybe thats what got to lisa)...Benjiwolf 14:48, 10 February 2007 (UTC)

[edit] Essential amino acid

I am looking for lists of essential amino acids required by various animals. In particular, I'm interested in domesticated animals e.i. cattle, cats, chickens...

Know of any source for this information? ike9898 21:36, 8 February 2007 (UTC)

I can really only help with cats; I'm afraid you'll need to find this sort of information out species by species. In most mammals, there are nine essential amino acids (histidine, isoleucine, leucine, lysine, methionine, phenylalanine, threonine, tryptophan and valine. Cysteine and tyrosine are classed as "semi-essential", and the others (alanine, arginine, asparagine, aspartic acid, glutamic acid, glutamine, glycine, proline, serine, and taurine) are considered nonessential.

In the cat, taurine is an essential amino acid; unlike dogs and humans, cats cannot synthesize taurine from methionine or cystine. In cats, arginine is also an essential amino acid, as it is the substrate necessary for them to produce ornithine. (Most mammals can produce ornithine from glutamic acid, but cats are deficient in an enzyme needed for this pathway). - Nunh-huh 00:52, 10 February 2007 (UTC)

[edit] Rubbing Alcohol

what will happen if a person consumes 1 fl oz. of rubbing alcohol? it's 70% isoproyl alcohol

Probably a seriously upset upper GI tract, followed by some vomiting. Isopropanol is not for human consumption. See below comment. -- mattb @ 2007-02-08T22:39Z

We're not qualified to answer questions about medical problems here at the Reference Desk. You should contact your local poison control center or your physician to receive reliable, thorough answers to these types of questions. TenOfAllTrades(talk) 22:48, 8 February 2007 (UTC)

[edit] Brain vomiting mechanism

A few years back I read a story in which a man died after receiving a "sherry enema", which raised his BAC to something like 0.47. (If you don't believe this, google "sherry enema".) But if one was to drink a bottle or two of wine, it's likely the brain would decide the body needs to vomit to get rid of the toxins.

The question is: When alcohol is involved, does the brain tell the body to purge the contents of the stomach because the alcohol/blood ratio is too high (regardless if the stomach is full of alcohol or not...the brain just "assumes" that's where it is), or because the alcohol simply irritates the stomach?

I.e. if someone became drunk through means other than traditional oral consumption, would they still vomit?

This may sound like a sophomoric question, but it is really a question about how the brain may be "tricked" into doing something that is, in this case, essentially useless in helping to solve the problem.

Thanks.

Darnoc 22:27, 8 February 2007 (UTC)

This is presented as information or observation, and not as medical advice. Drinking a large quantity of wine is just as likely to cause the person to go to sleep as it is to cause them to throw up. Deaths from frat initiations often occur when the person passes out or falls asleep, and their "buddies" put them in bed to sleep it off. They never wake up. If they vomit in their sleep they may aspirate the fluid and die from the effects on the lungs. Edison 00:49, 9 February 2007 (UTC)

I don't think it's sophomoric at all! According to Vomit#Vomiting_center, there are several sensory inputs to the vomit response mechanism. We would hope that the first-pass "poison sensor" is in the stomach, to induce vomiting before any has a chance to be absorbed. It does not appear that there is any "toxin" sensor there, though - only other assorted nerves. This seems in agreement with a normal situation - the vomiting does not begin immediately (sometimes it may take hours), I can only imagine that the perception of "poison" occurs after alcohol or other toxin has already entered the bloodstream. In that case, vomiting may do very little to eliminate poison (depending on how much is left in the stomach). Maybe a qualified biologist knows more about this. Nimur 00:50, 9 February 2007 (UTC)

More speculation: my impression is that fatal alcohol intoxication is usually the result of consuming massive quantities of hard liquor. For anything with a lesser alcohol content (e.g. beer or wine), you can't physically get enough of it into your stomach to then get a fatal amount into your bloodstream.

(But this begs the question of where the vomit response is triggered and why it's delayed. The explanation usually given in cases of fatal alcohol intoxication is that the victim drank too much too fast for his body to protect itself from, but this does suggest that a reaction involving organs other than the stomach is involved.) —Steve Summit (talk) 01:02, 9 February 2007 (UTC)

One other thing to keep in mind: Alcohol has been a significant source of calories for long enough that many people show adaptations in their metabolism to allow its use (e.g., increased levels of alchohol dehydrogenase and many other enzymes). It's entirely possible that starving for lack of beer (or from the loss of food due to drunken vomiting) has pressed some populations into different responses, despite a higher risk of alcohol poisoning.--Joel 08:31, 10 February 2007 (UTC)

[edit] "Lake Overturn"

I was searching for some information regarding most lakes' seasonal "overturn," or the event where the top layers of water mix with the bottom layers of water in a lake every spring and fall (or something like that). However, I have forgotten the name of this event. I figured it was like "Lake Overturn" or something like that, but that only redirects me to Limnic Eruption. If anyone knew the exact name of this event, could you please tell me the name, and if possible, the page? Thanks a lot!

--70.48.177.87 23:50, 8 February 2007 (UTC)

Sorry, I found the information after a little while. Thanks anyways though! --70.48.177.87 00:05, 9 February 2007 (UTC)

Where did you find it? I am also interested. --Spoon! 01:58, 9 February 2007 (UTC)

The best term I found was 'seasonal lake turnover', as explained here: [6] However, this would make a great article! --Zeizmic 02:48, 9 February 2007 (UTC)

If this happens twice a year, the lake is dimictic. If it never fully turns over (true of some deep lakes), it's meromictic (I do like that word!); if permanently frozen, amictic. Search on this page for other "mictic" words in this family. --Anonymous, February 9, 2007, 23:16 (UTC).

[edit] DRY ICE questions

Does carbon dioxide burn?

is carbon dioxide gas heavier or lighter than normal air?

thanks, anon

Consider reading the Carbon dioxide article, or the CO2 Fire Extinguisher section. Nimur 01:15, 9 February 2007 (UTC)

Sort of depends on your definition of "burning". See [7]. DMacks 01:30, 9 February 2007 (UTC)

(Wow! Cool. Thanks. I have never heard of that reaction. —Steve Summit (talk) 01:39, 9 February 2007 (UTC))

Also, if you touch dry ice to your skin for very long, you will freeze your skin and get what is usually called a burn (because it hurts just like one, and involves subcutaneous tissue damage just like one, even though it's caused by extreme cold rather than extreme heat). —Steve Summit (talk) 01:38, 9 February 2007 (UTC)

The density of carbon dioxide at 100 kPa and 0 °C is 1.6 kg/m³, where has air a density of 1.2 kg/m³ at sea level at 20 °C. So 1 m³ of carbon dioxide will be heavier than 1 m³ of air under similar conditions. But note that air contains carbon dioxide. - Akamad 01:47, 9 February 2007 (UTC)

Burning almost always means oxidizing, and it's not common to oxidize a stable oxide (like CO2). Nimur 02:55, 9 February 2007 (UTC)

Aw man i love dry ice every hollows eve the lunch lady would always drop a peice of dry ice in my drink and it would fog and carbinate and taste kinda like coke! you should try it once its fun and gets ya alot of attention. also i experimented with it using bubbles (i was very bored) and i noticed that the ones that didnt pop would get stuck on the ice and freeze (as a bubble) and it look really cool. i miss my youth Maverick423 14:37, 9 February 2007 (UTC)