Wikipedia:Reference desk/Archives/Science/2006 December 11

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December 11[edit]

Antimatter Production[edit]

Okay so if we built a particle accelerator around the equator of the Moon and it used superconducting magnets, how long would it take to produce one gram of antimatter? Of course using the trapping methods of todays traps. I'm asking this because I was reading the CERN article on antimatter and they talked about it taking about 100,000 years to produce one gram of antimatter with current accelerators. 23:25, 10 December 2006 (UTC)

Look at limiting parameters: how much electrical power is available to run the thing? Edison 15:54, 11 December 2006 (UTC)

Well lets say they developed a fusion power plant?

Would it be like creating matter from energy, limited by Einstein's equation E = mc2? .001 kg times (3*108 meter per second)2 = 9*1013 kg*m2 per second2 or 9*1013 Joules. To create 1 gram of matter from energy at an input power of 1000 megawatts, like from a large nuclear power plant, which equals a power level of 109 Joules per second, would take 9*104 seconds, or 25 hours, assuming 100% efficiency. The Antimatter article says they are many orders of magnitude away from 100% efficiency, so it would take several orders of magnitude longer with present technology. They mention in Antimatter "two billion years to produce 1 gram of antihydrogen." Startrek antimatter engine seem as far beyond todays technology as utility scale central generating stations were from the static generators of the 18th century, which produced only microamperes or milliamperes of electricity, but it was a soluble engineering and scientific problem of only 130 years or so to get from Benjamin Franklin power levels to Thomas Edison power levels. For lunar antimatter production, given there is never a cloud in the sky, consider solar energy. Solar energy reaching the Moon is 1366 watts per square meter (W/m2) per Solar power, so solar panels at typical 15% efficiency could produce 205 (W/m2). To produce the same 1000 megawatts on the Moon would thus require about 4.9 *106 m2 of solar collector, which would amount to an area about 2.2 km by 2.2 km. (Feel free to check the calculations and assumptions, since I hate math and it sometimes hates me). Edison 16:43, 13 December 2006 (UTC)

Thank You and yes I was thinking about solar energy also but assumed that the idea may be turned down but like you said no atmosphere and almost constant sunlight at the poles. 05:23, 14 December 2006 (UTC)

Vitamin C/citric acid[edit]

Are they the same thing, are they essentially the same thing, are there greater differences, or do they have no or little relation to each other? --Fbv65edel / ☑t / ☛c || 02:34, 11 December 2006 (UTC)

Not the same at all. See the vitamin C (ascorbic acid) and citric acid articles. --David Iberri (talk) 02:53, 11 December 2006 (UTC)
Thanks, I didn't really have the patience to go through both articles, but if there's a difference I guess I'll have to pick one to focus in on now… --Fbv65edel / ☑t / ☛c || 02:57, 11 December 2006 (UTC)
The quick-reference info box on the upper-right of each page lists the chemical formula of each, which is noticeably different. DMacks 04:16, 11 December 2006 (UTC)

horseshoe crabs[edit]

The article says: "The blood of horseshoe crabs is blue, which is a result of its high content in copper-based hemocyanin instead of the iron-based hemoglobin found, for example, in humans." Are there any other biological or synthetic means of transporting oxygen and if so what are they? Adaptron 04:53, 11 December 2006 (UTC)

Biological - many arthropods use hemolymph to circulate oxygen and nutrients. Synthetic - there are many. A pump in a fish tank serves to circulate oxygen into the water, for example. BenC7 10:54, 11 December 2006 (UTC)
The Hemolymph references says, "Hemolymph fills all of the interior hemocoel of the body and surrounds all cells. Hemolymph is composed of water, inorganic salts (mostly Na+, Cl-, K+, Mg2+, and Ca2+), and organic compounds (mostly carbohydrates, proteins, and lipids). The primary oxygen transporter molecule is hemocyanin." Is this the basis for the claim that wearing a copper bracelet is beneficial? Also although Seejyb's answer is closer to the answer I was looking for the thought came to mind as the result of your answer as to whether there might be or is a solid or liquid phase oxygen producer that could be transported by the blood to oxygenate the cells directly along with a corresponding carbon dioxide absorber? Adaptron 20:38, 11 December 2006 (UTC)
I don't know, but I wouldn't think so; it would be less efficient to carry something around that prodcues oxygen and absorbs CO2 - especially when those things can be transported themselves without any problems. BenC7 01:43, 13 December 2006 (UTC)
Well to speculate I suppose there would also be other problems like for instance if you tried to decompose water to get oxygen then you would have to do something with the hydrogen. Just wondering if there could be such a biological mechanism that could extract oxygen from say water or any oxygen bearing material including free gasseous oxygen in the atmosphere (sort of a super lung if you will) but I suppose that is only possible in science fiction. The problem being that when circulation stops then about four minutes later so does the brain. Adaptron 05:34, 13 December 2006 (UTC)
Hi Adaptron, If you look up the article on hemoglobin, the section on "Other biological oxygen-binding proteins" gives you a list of the oxygen carriers found in animals, with further links. As far as artificial carriers are concerned, there is a good article available on the net, titled "Blood substitutes".The latter may be more than you ask for, but come back and ask again if you get confused. --Seejyb 13:04, 11 December 2006 (UTC)
Hi Seejyb, and thanks very much for your references. The Blood substitutes reference is very clearly written and provided much of what I wanted to know except for empirical efficiencies. Nitrogen capacity was expressed for the comparative solubility of nitrogen of perfluorocarbon versus plasma but without empirical comparative data. Since treating decompression sickness is mentioned I was wondering whether any substitute is likewise used in sports medicine for its treatment or enhancement capability. Adaptron 20:38, 11 December 2006 (UTC)

Even plants are known to get in on the action. See Leghaemoglobin, Legumes use it to feed oxygen to bacteria in nitrogen fixing nodules. David D. (Talk) 00:17, 12 December 2006 (UTC)

Some animals don't even have oxygen carrying molecules. I recently heard a report about Antarctic fish without red blood cells. It seems their blood has the same partial pressure of oxygen as the surrounding water, and they compensate by having an oversized heart capable of pumping much more blood around. (It seems that at cold temperatures, blood with red blood cells in it is just too viscous). -- 21:32, 12 December 2006 (UTC)
Do these fish have gills or do they absorb oxygen and release carbon dioxide directly through their scales? Adaptron 06:11, 13 December 2006 (UTC)
See also blood substitutes. --Kjoonlee 03:32, 14 December 2006 (UTC)

3 questions[edit]

1) whats causing the universe to expand?

2) is it possible to live with radiation? (think the hills have eyes)

3) the brain grows with intelligence, but can it grow enough to effect the size of the skull?

PitchBlack 06:05, 11 December 2006 (UTC)

1) Start with Big Bang, not sure what you mean by causes, but there are a few theories out there about why it seems to be growing at a faster rate.
2) See Nuclear fallout, we're all living with a little bit of radiation today! There are, of course, lethal doses though.
3) Check out Human skull. The brain doesn't really grow with intelligence, it grows as we age but once the skull plates fuse your head can't get any bigger. --Cody.Pope 06:41, 11 December 2006 (UTC)

1) Inertia left over from the Big Bang causes the universe to continue to expand (an object in motion stays in motion unless another force acts upon it).

2) People are highly variable in their ability to withstand differing levels of radiation. At high doses, people can die quickly of radiation poisoning. At lower doses, the person recovers from radiation sickness, or doesn't have any symptoms in the first place. However, genetic damage may have been done which ultimately leads to cancer or other problems.

3) When people say the brain "grows with intelligence", they mean more connections are formed between neurons, not an overall increase in the brain's volume. StuRat 08:00, 11 December 2006 (UTC)

The answer to this question is actually a qualified "yes". In nearly all infants the skull simply grows with the brain, and there is a strong statistical relationship between learning in infancy and skull size at 1 year of age. Severe deprivation can impair both intelligence and head size, but the relationships are complex. alteripse 12:41, 11 December 2006 (UTC)
  • 2. It depends on how much radiation, what kind of radiation it is, where it is coming from, and what you consider "living with" to mean (many radiological exposures will not kill you or produce any obvious symptoms immediately, but in a few decades time you will find statistically much higher rates of cancer, birth defects, etc. in the exposed population. See Project 4.1 for one description of such a population). -- 16:46, 11 December 2006 (UTC)


How Cannons are working? Principle of Cannons.

See cannon. Basically, some explosive is detonated behind a ball, shell or lead shot, inside a cylinder, causing high pressure, which accelerates the projectile(s) out of the end of the cannon at high velocity, where it undergoes ballistic motion, following a roughly parabolic path to the target. A cannon typically fires at an angle less than or equal to 45 degrees, while a mortar first at higher angles. StuRat 06:44, 11 December 2006 (UTC)

Request for Equivalent Specification[edit]

Dear Sir,

Please help me to know the equivalent Indian or other standard for Eyebolt DIN-444. I am waiting for your response.

Thanking you.

Sanju Balial.

Searching the internet for "DIN-444 eyebolts" gave a number of sites of sellers, which list other standards alongside the DIN-444. The specifications themselves are not free. --Seejyb 13:30, 11 December 2006 (UTC)

Surface Tension[edit]

What is Surface Tension? —The preceding unsigned comment was added by (talkcontribs).

That property described in the article cleverly entitled surface tension.
Atlant 12:47, 11 December 2006 (UTC)

surface tension is the property of liquid, by virtue of it, it behaves like a sort of elastic film on which a tiny insects can run. to analyze what actully is surface tension, so you to think from the molecular level. we know that there are inter-moleuclar forces act between two molecueles. to have a minimum force, water molecules try to shrink as much as possible.thus surface molecules shrink too much and thus water in buket aquires spherical shape.

For a brief summary, it's the force that makes water (or any other liquid) form into droplets and also allows light objects to rest on the "skin" of the liquid instead of sinking. Some insects can even walk on the surface of water, using surface tension. StuRat 19:00, 11 December 2006 (UTC)
On the other hand, it could describe someone who can hide his/her inner calmness. Clarityfiend 06:35, 12 December 2006 (UTC)


if a lamp has a luminous intensity of 1200 candellas acting as a point of source what would be the illuminance in lux at a distance of 6 meters and what would be the problems of associated human comfort in this lighting many thanksAcnbrewerg 14:41, 11 December 2006 (UTC)

We don't answer homework questions here, sorry. Try looking in your textbook's chapter on it. X [Mac Davis] (DESK|How's my driving?) 15:25, 11 December 2006 (UTC)
You can find info on this topic at Luminance, Luminous intensity and Lighting. Please come back with any more questions you have after reading those articles. Edison 15:59, 11 December 2006 (UTC)

Natural Selection theory without 'agency'?[edit]

Under 'Natural Selection' I read "It works on the whole individual, but only the heritable component of a trait will be passed on to the offspring, with the result that favorable, heritable traits become more common in the next generation".

Do traits relate to behaviour or only physical characteristics like eye colour? I observe that among humans it is behaviours (link character 'traits') that inclines for success in reproduction - and that the parents usually carry a huge role in propagating behavioural traits including those around 'religion' and 'values' etc.

It seems to me that any account of natural selection in 'modern humans' must necessarily be incomplete and handicapped without reference to transmission of traits that may be non heritable but definitely transmitted across generations...?

Gomackay 16:50, 11 December 2006 (UTC)

Biological evolution with natural selection applies to heritable traits including heritable behaviours (things like wasps building nests. dogs hunting in packs, birds singing a specific type of song). The very great majority of human behaviours aren't genetically inherited, they're acquired through learning. So one might have a basic biological propensity for building things or for having religious feelings, but the design of a bridge or the philosophy of a religion are obviously not something one is born knowing. While natural selection still applies to modern humans, and evolution is still occurring to us, its effects are obscured (and mostly overwhelmed) by artificial selection factors. -- Finlay McWalter | Talk 16:59, 11 December 2006 (UTC)
See also Social Darwinism. Hipocrite - «Talk» 17:24, 11 December 2006 (UTC)

I think one of the ideas you are hitting on are Memes. The idea that ideas are "heritable" and undergo natural selection like processes is controversial, but to me it makes sense. Sifaka talk 21:53, 11 December 2006 (UTC)

While the details of many specific human behaviors are learned, humans can have genetic predispositions towards certain patterns of behavior. Twin studies suggest that some human behavioral patterns have a very high level of genetic predisposition. Some genetic studies have been interpreted as indicating that people can be genetically predisposed to religious belief, prompting interest in neurotheology. --JWSchmidt 01:48, 12 December 2006 (UTC)

Also, keep in mind that most of natural selection traits are not testable, meaning they are observable with theories used to describe the observable, but it has almost no predictive value as is required for most scientific theory. Natural selection is provable as is evolution, but predicting which meme or trait will be selected for in the future is elusive. The environment is simply too dynamic and complex. But the interesting thing is that hindsight is employed in all these cases to show natural selection. --Tbeatty 04:35, 13 December 2006 (UTC)

Human body temperature[edit]

Frequent reference desk responders may wish to review hidden comments below

Hi, many of my friends are health care professionals, but none has ever been able to answer this question. My resting, healthy, body temperature (measured under the tongue) is 97.2 F. I've contracted a virus, and today my temperature has gone up to 98.6 F (I feel pretty rough!). Is this the equivalent of a 100 F fever in a person whose 'normal' temperature is 98.6 F? Thanks in advance L.Parry

You will find a great deal of information on body temperatures at Thermoregulation. Can you read that and come back with your question again if you need more info? Hipocrite - «Talk» 18:01, 11 December 2006 (UTC)
Following our articles, I got to [1] which looks helpful. Hipocrite - «Talk» 18:02, 11 December 2006 (UTC)

The fact the nobody has ever created 'absolute zero' conditions, and freely admit that such a thing is impossible, goes a long way in deconstructing the entire notion of temperature. To be hot is to be hot, to be cold is to be cold, and metabolism is pretty much the only thing worth mentioning when it comes to humans and body temperature. Just my 2 pents. Mathiemood 18:48, 11 December 2006 (UTC)

The above comment is inaccurate. Please see Absolute Zero and Bose-Einstein condensate. Hipocrite - «Talk» 19:06, 11 December 2006 (UTC)
Your spelling of inaccurate is inaccurate, Hipocrite :) Mathiemood 19:24, 11 December 2006 (UTC)
What do you mean "deconstructing the entire notion of temperature"? That phrase makes no sense to me. —Keenan Pepper 19:32, 11 December 2006 (UTC)
As far as I can tell, he;s basically implying that temperature is merely the human manifestation of thermal energy (just like Centrifugal force is a human manifestation of an imagined force). However; temperature certainly exists in some contexts, indeed it is the only way to make many thermodynamic systems make sense: a bathtub full of lukewarm water has more thermal energy than a small piece of red-hot metal, yet when the metal is dropped into the water, the energy is transferred from the lower energy metal to the higher energy water! This makes far more sense when you think in terms of temperatures; the energy which manifests itself as the 900°C of the metal goes to warming up the 30°C bathwater, but since the metal only has very little energy compared to the water (due to specific heat capacity), the bath only warms slightly. Laïka 17:40, 12 December 2006 (UTC)

I believe you are correct, if your temp is 1.4° F above normal, then you have a fever. My dad has something similar, but on BP. His is normally what would be considered high. When we let a doctor take action to bring it down to what is considered "normal", he almost passed out. Doctors tend to treat people as if "one size fits all", when it does not. StuRat 18:55, 11 December 2006 (UTC)

Please review Hypertention for more information on elevated human blood pressure. Hipocrite - «Talk»
"<!-- A user has alleged that the comment directly below are speculative and inaccurate. Consider removing them, and not posting comments of this type in the future. -->" If anyone thinks a comment is inaccurate, just point it out. There's no reason to secretly tell users to delete it. --Bowlhover 22:43, 11 December 2006 (UTC)
On the other hand, enzymes and stuff denature at a nonvariable temperature, so in that respect your low body pressure makes you lucky. --AstoVidatu 01:47, 12 December 2006 (UTC)

solid state pulsed laser[edit]

What's the simplest configuration of solid state laser that you can think of, and how easy would it be to find the components necessary to build one?-- 19:36, 11 December 2006 (UTC)

Please see our article on Laser construction.-- 03:03, 12 December 2006 (UTC) (just kidding, sorry I couldn't help)

What are cleaning erasers made from?[edit]

Anyone know how those Mr. Clean Erasers work and what they are made from? They seem like simple latex foam. -- 19:46, 11 December 2006 (UTC)

Formaldehyde-Melamine-Sodium Bisulfite Copolymer. No joke. [2]. Hipocrite - «Talk» 19:52, 11 December 2006 (UTC)

That's hilarious! :) Vespine 21:49, 11 December 2006 (UTC)
I don't get it? -Username132 (talk) 00:33, 12 December 2006 (UTC)
Wont someone explain it to me? --Username132 (talk) 18:10, 13 December 2006 (UTC)
The common name is melamine. Tuckerekcut 22:37, 11 December 2006 (UTC)
So is it pure melamine or is it Formaldehyde-Melamine-Sodium Bisulfite Copolymer?? Magic Eraser. --Russoc4 22:44, 11 December 2006 (UTC)
The melamine is the base ingredient - I believe it is bound to formaldehyde and sodium bisulfite as a copolymer. Hipocrite - «Talk» 23:03, 11 December 2006 (UTC)

Sleep apnea and oxygen deficit[edit]

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I've read in several places that people with sleep apnea can have depleted blood oxygen all the time, but I have never read how this works? I can understand building up an oxygen deficit during sleep, but doesn't it get restored to normal during waking hours? Anchoress 21:02, 11 December 2006 (UTC)

I can take a guess. I'd think that the mechanism which tells them to breathe is "tardy", waiting longer than it should. This would cause them to breathe less during the day and night. Of course, they can force themselves to breathe more often for a little while, but nobody could do that for long. StuRat 21:50, 11 December 2006 (UTC)
Actually, frequent drops in blood oxygen (during sleep) can cause damage to the heart and lungs, along with a variety of other possibly mechanisms. See "Sleep Apnea and Cardiovascular Disease", Am J Respir Crit Care Med Vol 164. pp 2147–2165, 2001, to get started. Hipocrite - «Talk» 23:00, 11 December 2006 (UTC)
Hey ms a, that reference says "Studies of patients with CHF and CSR–CSA have consistently shown them to be normoxic while awake (194, 214).", so maybe you can look for "Pickwick syndrome / Obesity hypoventilation syndrome" (I don't see a WP article on this) or "cor pulmonale" (advanced). Both can cause daytime/awake hypoxemia. The former is a cause of sleep apnoea, the latter a possible result. Let me know if you want to know more. --Seejyb 00:40, 12 December 2006 (UTC)
OK thanks for all the answers, I'll get reading. Anchoress 00:43, 12 December 2006 (UTC)
Correction, there is an article about Pickwickian syndrome, but that is about history, not modern ideas. --Seejyb 00:52, 12 December 2006 (UTC)
See alsoPolysomnography , a study which can answer lots of questions, as well as Positive Airway Pressure. Edison 21:57, 12 December 2006 (UTC)
I don't see the connection between those two articles and my question. Anchoress 06:48, 13 December 2006 (UTC)

Physics question- building a crane[edit]

Can u design it as much simple as possible ? I am not good in Physics...

Purpose: To design and build a DC motorized crane/ wench to lift a pile of paperclips

I must submit sketches of the design (this is so hard) ...and explain these questions:

what materials do u use and why ? what design features will the crane have and why ? how will the motor work ?

============Anyone can give me the answer for these cause I have no idea how to start or do it +_____+

Or you can give me the website to take a look at it

Thanks a lot for you guys time...I am really stupid in Physics...

It sounds like you may need more guidance than we're well equipped to offer here. I would suggest talking to your instructor. Friday (talk) 21:24, 11 December 2006 (UTC)
PS. As for electric motors, see electric motor. There's an explanation there of how they work. Friday (talk) 21:28, 11 December 2006 (UTC)

The simplest crane would have a single beam, anchored with a peg at the bottom, and with a sting at the top that's wrapped around a pin sticking out of the motor. Instead of a hook, you might want to put a magnet on the end (if the rules allow it) to pick up paperclips. Is that enough info ? StuRat 21:38, 11 December 2006 (UTC)

              . / v hook or magnet
     string .  /
          .   / beam
        .    / 
 motor O    + peg
====================== base

StuRat 21:42, 11 December 2006 (UTC)

This isn't so much a physics question as a practical, hands-on mechanical design problem. If you've never built much of anything, this is going to seem like a forbidding problem. But if you can set aside your uncertainty and self-doubt, and roll up your sleeves and start playing, you'll learn a lot.

Take a look at our Crane (machine) article. Do a google images search on "crane". What are the basic elements of a crane? (StuRat already gave the answer away.) What sorts of materials do you have available to you that you could build a smaller, not-as-strong-but-still-sorta-functional model with?

Did you ever play with Meccano or Erector sets or Lego? Can you get your hands on any of those today? You may have thought they're "just toys", but they're tools, ideal for this kind of learning. (For example, sitting right next to me is a nice new box full of 8288, which I haven't started building yet.)

Good luck! If you have any specific questions, ask away! But as Friday said, if you need lots of help, you really need to ask your instructor. Nobody here is going to do your project for you; you won't learn anything that way. —Steve Summit (talk) 00:55, 12 December 2006 (UTC)

For the beam, you can try using a long, narrow piece of wood with a trench running lengthwise through it. Put the string into the trench, and glue a thin piece of wood on to cover the trench. Of course, if your project doesn't need to look professional, you can glue paper to cover it instead.
To secure the beam to the base, maybe you can use nails? Just some ideas. --Bowlhover 04:35, 12 December 2006 (UTC)