Wikipedia:Reference desk/Archives/Science/2009 January 19

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January 19

What kind of audio processing is this?

In signal processing terms, what kind of processing gives the opening refrain of the song Body II Body its distinctive quality? —Preceding unsigned comment added by 173.49.15.243 (talk) 02:20, 19 January 2009 (UTC)

Is this the song you're talking about? [1] I don't notice anything special about the first few seconds, except that the voice has an unusual impulse response i.e. there's perhaps some reverb and definitely some kind of band-pass filter which is reducing the apparent bandwidth of the signal by attenuating high and/or low frequency signals. There might be a hint of distortion too. This makes the audio sound like a low-quality, narrow-band audio system (like a telephone or cheap walkie-talkie). 4.242.147.97 (talk) 04:51, 19 January 2009 (UTC)

Yes, that's the song I was talking about; I was just using it as an example. The voice sounds bandwidth-limited, but that doesn't seem to be the only thing done to it. I'm trying to find out exactly what's done to it to give it the kind of quality that it has. --173.49.15.243 (talk) 05:20, 19 January 2009 (UTC)

Don't know what processing you'd use, but a similar distortion could be achieved using s.th like this [2] - --76.97.245.5 (talk) 01:05, 20 January 2009 (UTC)

Sounds to me like they took the bass out of (only) the voice-track to make it sound "tinny." This is a fairly common technique in many pop-music (and other genre) songs. Nimur (talk) 03:19, 20 January 2009 (UTC)

Is the areola/nipple of the breast (any breast, but a female breast I'm thinking of) a mucous membrane?

I mean, the holes that the milk comes out of must count for something... so could sucking a woman's nipple theoretically be a way in which AIDS could transfer? This is a serious question. It's not medical advice and nor is it a joke - it's just something I would like to know the answer to.--Terminal left (talk) 05:16, 19 January 2009 (UTC)

Theoretically it could if a fluid containing some HIV virons was transferred through the nipple of the suckee, and into a cut in the mouth of the sucker. That means if the nipple is expressing milk, is infected in some way, or is pierced and not fully healed. A healthy nipple from a non-lactating female has no real potential to transfer HIV. [3] Rockpocket 07:48, 19 January 2009 (UTC)

A quick googling brings up conflicting information. Apparently HIV has been detected in the milk and breastfeeding is listed as one of the ways a mother may transmit the virus to her child, but there's also claims that breast-feeding reduces the risk of transmitting the virus. EverGreg (talk) 09:54, 19 January 2009 (UTC)

Is that because the colostrum will contain antibodies against HIV, so the infant gets a head start in fighting it? --Tango (talk) 11:14, 19 January 2009 (UTC)

The study (The Lancet, March 2007) was only a statistical study, but the researchers hypothesis was that the mucous membrane within the intestines might act as a barrier to HIV infection, with the breast milk reinforcing the lining.. I've never heard of this effect from breast feeding, but it's not my field either. EverGreg (talk) 11:20, 19 January 2009 (UTC)

So just saying 'this is not medical advice' is the easy way to get medical questions answered? Especially if it is a sexually orientated question!

It depends whether we believe you, or not. In this case, I'm not sure I would have believed the OP... --Tango (talk) 16:36, 19 January 2009 (UTC)

Its not medical advice because it doesn't diagnose, address or advise about a treatment for medical condition. Its a question about the transmission of a virus, and can be answered based on knowledge of how the virus functions. If the OP chooses to utilize that newfound knowledge for medical or prophylactic purposes that is entirely his choice, but no-one has provided an answer recommending any course of medical action. Rockpocket 20:57, 19 January 2009 (UTC)

Dodging the question here, but looking up milk banks and donated milk gives the info that other viruses are transferable via breast milk. Polypipe Wrangler (talk) 22:55, 19 January 2009 (UTC)

Apparent violation of the Second law of thermodynamics at quantum level?

I was wondering weather the spontaneous creation of a particle-antiparticle pair out of nothing could decrease entropy in a closed system.

(1) For example, if in an isolated container were nothing but just vacuum, wouldn't the appearance of a particle create information?

(2) Or if the container had one single radioactive particle (or just a small number of them, not allowing us to use statistics), the decay of it seems to be without an external cause.

(3) On macroscopic scale it's nearly impossible to occur, but looking at the (nearly zero, but not equal to zero) possibility of a chunk of matter spontaneously rearranging into another chunk of matter with, let's say, higher potential energy, wouldn't it violate the second law of thermodynamics? --131.188.3.20 (talk) 10:20, 19 January 2009 (UTC)

This involves some nuances of entropy and information. It's possible for entropy to decrease purely by chance, since the law of nondecreasing entropy is a statistical law. If you invoke a system with few components, notions like entropy, gas pressure, temperature and such break down. A violation of the conservation of energy, which you'r also invoking here, is a wholly different matter. EverGreg (talk) 11:07, 19 January 2009 (UTC)

The second law is really an emergent property of statistical mechanics, which tells us that the average behavior of a thermally interacting collection of N particles tends towards a maximum in entropy and spontaneous deviations from that maximum have a probability proportional to $1 \over {\sqrt {N}}$. At macroscopic scales N is typically huge and the probability of measurable deviations from the second law is vanishingly small. However, whenever one starts talking about small number of particles it is entirely possible that an instantaneous state will show a large variation from the average, entropy-maximizing state. Dragons flight (talk) 11:15, 19 January 2009 (UTC)

Agreed. The second law of thermodynamics doesn't exactly forbid a decrease in entropy in a closed system, it just says that this is very unlikely - and as you add more particles, degrees of freedom and microstates, a violation of the second law becomes exponentially more unlikely. Virtual particle/anti-particle pairs exist for such a short time that any theoretical decrease in entropy is unobservable because of the Heisenberg uncertainty principle. Even if one of the pair of particles is captured by a black hole, and the other escapes, then this causes an increase in the black hole entropy which is greater than the decrease in entropy outside of the black hole. Gandalf61 (talk) 11:25, 19 January 2009 (UTC)

The issue seems to be that you have artificially constrained your system so as to give the appearence of a "closed system" or otherwise an violation of the Second Law without actually doing so. In any real world scenario, the second law holds perfectly so long as you don't purposefully ignore some bit of information which would cause it to appear to be violated. Once you consider that in reality, the only closed system is the entire universe, then any real situation obeys the laws of thermodynamics just fine... --Jayron32.talk.contribs 12:33, 19 January 2009 (UTC)

MANUFACTURING PROCESS

how close tolerance(that is gap) can we get if we swage stainless steel and Zr-4,can anyone get 0.1 microns?203.199.205.25 (talk) 10:55, 19 January 2009 (UTC) i mean if two tubes are swaged. —Preceding unsigned comment added by 203.199.205.25 (talk) 03:29, 20 January 2009 (UTC)

Fresnel drag

Is "Fresnel drag" the same concept described at Aether drag hypothesis? The reason I'm asking it that Sagnac effect has a redlink to Fresnel drag and I want to make sure I don't link to something completely off-base. I'm not familiar enough with these concepts to be sure I've got the right target page, although from context I think I may. Thank you. 152.16.51.125 (talk) 11:28, 19 January 2009 (UTC)

Yeah, I think you have found the right place. Fresnel drag is covered in that article and this confirms you have the rigt concept. SpinningSpark 19:25, 19 January 2009 (UTC)

Thank you. I've directed that redlink to the correct page. 152.16.59.190 (talk) 01:25, 24 January 2009 (UTC)

Is there any solvent in the world has ph below 1.5 but without bubbles when spraying?

Is there any solvent in the world has ph below 1.5 but without when spraying? —Preceding unsigned comment added by Chlim (talk • contribs) 14:44, 19 January 2009 (UTC)

Creating a solution of pH < 1.5 is fairly easy. Concentrated strong acids such as Hydrochloric acid and Sulfuric acid are fairly easy to come by, and as far as I know, they aren't all that prone to frothing or bubbling. --Jayron32.talk.contribs 18:46, 19 January 2009 (UTC)

I just want to point out how important it is to dilute those particular acids, since they're really, really strong. With pKa's of -8 and -3, respectively, the pH's of the pure stuff is a lot lower than 1.5. Even if you don't consider their ridiculously strong acidity, their pure forms really need to be worked with in a fume hood, and I can also tell you from experience that it's a particularly unpleasant experience to inhale their fumes, so if you do use one of them in their concentrated forms, be sure that you know how to dilute the stuff properly, and have access to a fume hood or respirator. – ClockworkSoul 21:26, 19 January 2009 (UTC)

All absolutely true. However, most weaker acids are difficult to get in solutions of a pH that low. You can, of course, purchase stock solutions of HCl or H2SO4 already diluted to, say, 1 normal concentration (pH 0) which is much less problematic to handle than the concentrated stuff. --Jayron32.talk.contribs 22:39, 19 January 2009 (UTC)

tensing head/neck muscles

Is it possible to damage the brain from constant tensing of the neck and head muscles? (constant meaning it happens more or less consistently for more than 12 straight hours) —Preceding unsigned comment added by 75.23.83.54 (talk) 15:09, 19 January 2009 (UTC)

We can't give medical advice, I'm afraid. If you are concerned, see a doctor. --Tango (talk) 15:25, 19 January 2009 (UTC)

I am not asking for medical advice, I am just curious. It seems like it could but at the same time the notion seems impossible. —Preceding unsigned comment added by 75.23.83.54 (talk) 16:24, 19 January 2009 (UTC)

With the usual warnings of not considering this to be in any way correct or comprehensive: unlikely, vice versa on the other hand it's rather well documented for many conditions. Neck muscle tension is one if the items checked in a neurological evaluation. You might find the following pages helpful for drawing your own conclusions: Internal carotid artery, Head and neck anatomy, Cerebral hypoxia, Encephalopathy, Hypertonia, Headache. Good hunting.--76.97.245.5 (talk) 00:14, 20 January 2009 (UTC)

Thank you very much :) —Preceding unsigned comment added by 75.23.83.54 (talk) 00:50, 20 January 2009 (UTC)

stimulated emission

in a laser, a higher energy electron emits a photon and jumps to a lower energy level. How does another photon stimulate this electron to emit another photon? in a laser, how do the photons have the same phase and frequency?--Harnithish (talk) 15:26, 19 January 2009 (UTC)

We have an article on Lasers. Actually we have MANY articles on Lasers. If you read the main article, and follow the links from there, you can answer your own question. They are quite detailed and fairly accessable (compared to many Science articles at Wikipedia). --Jayron32.talk.contribs 18:43, 19 January 2009 (UTC)

Is there a chance that Mars will be swallowed up/?

Is there a chance mars will be swallowed up by the time sun becomes a white dwarf? Some sources had said there is a chance Mars will be swallowed up before sun becomes a white dwarf, just less likely than that of Earth.--69.226.46.118 (talk) 18:28, 19 January 2009 (UTC)

If you read Red giant#The Sun as a red giant, it describes the situation quite well. It seems that Mercury and Venus are definately toast, and the earth is likely a goner too, while its about even money on whether or not Mars in some form will survive. --Jayron32.talk.contribs 18:34, 19 January 2009 (UTC)

• What you mean by its about even money on whether or not Mars in some form will survive.--69.226.46.118 (talk) 18:38, 19 January 2009 (UTC)

I believe he means that scientists cannot say with any certainty given our current knowledge of stellar evolution.-RunningOnBrains 18:51, 19 January 2009 (UTC)

"Even money" means about a 50/50 chance, that is, it's as likely to happen as it is not to happen. --Tango (talk) 18:55, 19 January 2009 (UTC)

• Uh, is the calculation even right? The academic paper said sun's maximum extent suppose to be 1.15 AU, sun's lost of mass could push Venus and Earth's orbits to 1.24 AU and 1.71 AU, that's enough to keep those planets from being engulfed. What they said about Earth been dragged into sun is only news, doesn't mean it's right. Who said sun's expansion can hit Mars' orbit?--69.226.46.118 (talk) 18:56, 19 January 2009 (UTC)

I don't think it's likely Mars will be engulfed, I haven't seen any reliable sources suggest it. It will certainly be scorched, though. --Tango (talk) 19:09, 19 January 2009 (UTC)

I always thought Mars is engulfed by 0% chance, Venus by 90%, and Earth by 60% chance, or is it Mars is engulfed by 30% chance, Earth by 65%, and Venus by 99%.--69.226.46.118 (talk) 19:39, 19 January 2009 (UTC)

At any rate - it's worth pointing out that the disruption in solar output - the short, sharp high-energy bursts as the sun goes through this trauma - the orbital disruptions and all else - means that the earth and mars might "survive" in a technical sense - but without atmospheres or oceans, possibly with their surfaces reduced to molten lava flows and their axes tilted to make areas or perpetual (red!) sunlight and other areas of perpetual night. It's not a matter that lifeforms on earth could possibly care about because there won't be any! SteveBaker (talk) 19:56, 19 January 2009 (UTC)

• Steve, We have source said Venus might survive, I thought if Venus survives, it will just be black and hot with no life AT ALL, just land uniform surface as molten lava, just like Earth. 1.15 AU sun could push Venus' orbit to 1.24 AU. --69.226.46.118 (talk) 20:13, 19 January 2009 (UTC)
  • Why, 69.226, are you arguing? You asked a question which implied you didn't know and wanted more information, and when you are presented with links to that information, you start to argue about it? If you already had your opinion, why ask the question in the first place?!? --Jayron32.talk.contribs 20:58, 19 January 2009 (UTC)

  Why do you emphasise "at all"? Venus doesn't have any life at all now, as far as we are aware... --Tango (talk) 21:28, 19 January 2009 (UTC)

Are you impugning the first-hand findings of Professor Abbott and Dr. Costello? Or this noted trio of scientists? Clarityfiend (talk) 22:24, 19 January 2009 (UTC)

This said Venus could survive.--69.226.46.118 (talk) 22:51, 19 January 2009 (UTC)

And this too.--69.226.46.118 (talk) 23:00, 19 January 2009 (UTC)

Bob the alien's website said there is a chance that mars could be swallowed up as well. I question about updated and trustworthy of those sources.--69.226.46.118 (talk) 23:08, 19 January 2009 (UTC)

When they say "survive" - they mean as a burned out cinder with no atmosphere, etc. It's just possible for venus to "survive" within the limits of that meaning. The precise dynamics of what happens when a star does this aren't perfectly understood - and whether there would be enough force involved to push the existing planets outwards or whether they'd be pulled inwards to certain doom depends on too many variables for it to be calculated as a certainty. The probability of "surviving" obviously depends on the distance from the sun - so mercury is regarded as certain to go - venus is very likely to go too (but there is a chance) - out here where the earth is, it looks like it's a 50/50 chance and for mars the odds are evidently better than 50/50, Jupiter and everything further out is "safe" (although it's hard to imagine that it would be unaffected!). Trying to pin things down more accurately than that is impossible - even the experts can't agree. So - you get a statistical answer with large error bars. SteveBaker (talk) 23:11, 19 January 2009 (UTC)

• Can you restate and for mars the odds are evidently better than 50/50, I'm sorry I don't understand.--69.226.46.118 (talk) 23:27, 19 January 2009 (UTC)

Well, if the odds for the Earth are 50/50 (which certainly seems to be the consensus opinion) - and Mars is further away than the Earth which means it's odds of survival are definitely better - so we can reasonably say that Mars has a better than 50% chance of survival. SteveBaker (talk) 03:20, 20 January 2009 (UTC)

Original use of copper wire, before electric use

When early experimenters like Humphry Davy , Michael Faraday , and Joseph Henry started doing electrical experiments, they were able to buy considerable lengths of copper wire. They did not have to have it custom made. Why was it manufactured in large amounts, before it was useful as an electric conductor? It is more expensive than iron wire and far weaker, although malleable and flexible. What was its original use in the early 19th century? Edison (talk) 19:41, 19 January 2009 (UTC)

It has the advantage of not rusting. Copper wire will turn green, but won't fall apart like a rusty iron wire will. So, I imagine any outdoor use for wire, like in building fences, would tend to have used copper, or a copper blend, like brass or bronze, at least until stainless steel was invented. Copper wire is also more malleable, meaning it can be bent more without breaking, which would make it as good choice for things we would now use plastic zip-ties to do. StuRat (talk) 20:11, 19 January 2009 (UTC)

Take a look here. -hydnjo talk 22:25, 19 January 2009 (UTC)

Copper wire, especially the very fine wires used in early electrical experiments, is also used in making jewelry. --Carnildo (talk) 01:03, 20 January 2009 (UTC)

Joseph Henry (1797-1878), an American scientist, did some significant early work in electromagnetism, including invention of the relay. He could not find insulated copper wire for his experiments, so his wife ripped her silk wedding gown into strips and wrapped them around copper wire for him to use. She probably used some sort of glue or paste, or maybe shellac, to hold the cloth in place. - GlowWorm. —Preceding unsigned comment added by 174.130.253.174 (talk) 01:59, 20 January 2009 (UTC)

Another book on this subject is Copper Wire and Electrical Conductors: The Shaping of a Technology, by Blake-Coleman. Amazon has it, but the price is pretty hefty. – GlowWorm. —Preceding unsigned comment added by 174.130.253.174 (talk) 02:17, 20 January 2009 (UTC)

Carding wool.—eric 07:57, 20 January 2009 (UTC)

I checked Google Books for 18th century mentions of copper wire, and found that it was often used, along with brass or iron, to connect bell pulls throughout a house with signal bells in servant's quarters or the kitchen. When I had seen the term "bell wire" I thought it referred to its modern use for connecting doorbell pushbuttons to the transformer and bell or buzzer. That may have been the common usage which kept it available in quantity in the eaarly 19th century. Edison (talk) 22:34, 21 January 2009 (UTC)

I would have thought that copper wire would stretch too much for such usage.--GreenSpigot (talk) 02:26, 22 January 2009 (UTC)

Longevity of woman

What is the leading scientific theory on the reason of this disparity in average lifetime? My speculative opinion is that it is more sociological than biological. Waiting to hear from you folks.Bastard Soap (talk) 22:30, 19 January 2009 (UTC)

Well, this isn't really a place to discuss unsupported opinions, but we do have the following section from one of our articles: Life expectancy#Gender differences in life expectancy which has some links to some outside sources, as well as giving a short overview of some potential sources of the differences. --Jayron32.talk.contribs 22:34, 19 January 2009 (UTC)

The generally accepted theory is that it is stressed levels. As women have been more and more likely to enter the work force in recent decades the longevity disparity has shrunken. So you would be correct that it is more sociological than biological. I google search for "Why do women live longer than men" gave me several useful articles that talk about many of the more specific reasons also talking about the actual causes of deaths relating to each gender. Here is a short TIME article [4] and here is an article from WebMD [5]. Anythingapplied (talk) 06:15, 20 January 2009 (UTC)

I think that the macho bullshit also has something to do with it, women are generally more tollerated for ridiculous emotional release while men almost universally frown upon for any emotions of the not wanting to fuck or kill types. Is this a reasonable factor in the jumble? Bastard Soap (talk) 11:33, 20 January 2009 (UTC)

As it's a big topic you might enjoy this search for "gender differences in emotional expression"[6]. Wikip also has the article emotional expression – it's very small, but the links at "see also" look better. Julia Rossi (talk) 17:52, 20 January 2009 (UTC)

That reminds me of a joke my grandfather used to tell: why do men die before women? Because they want to. My grandmother out lived him by 16 years, by the way. – ClockworkSoul 20:56, 20 January 2009 (UTC)

I've heard it to be because men die at a young age in war; that a number of counterbalancing women die at a young age in childbirth is no longer so true. - Nunh-huh 21:46, 20 January 2009 (UTC)

While it may have an effect, I don't think it's enough to explain the difference. I'm pretty sure if you look at the life expectancy at 50 or 30 or something you'd find that there is still a resonable age gap which would imply it's not simply because men died young in wars. While you could argue the wars killed a lot of the men who would have lived the longest, it doesn't seem that likely to be such a big factor to me. Besides that many countries which have not had a significant number of people dying in wars still have the difference I believe. Nil Einne (talk) 20:41, 21 January 2009 (UTC)

Monks and nuns life nealy to the same age so the monastery and the stile of living there must have an influence.--23:26, 21 January 2009 (UTC)

Types Of Cells Containing Nuclear Pores

Just a quick question, are Nuclear Pores found in both plant and animal cells?

Thanks

Our article nuclear pore suggests that they are present in all cell nuclei. Plants and animals are all eukaryotes, so they all have nuclei and hence pores. Algebraist 00:28, 20 January 2009 (UTC)

That's correct. The nuclear pore is vital, allowing selective transport into and out of the nucleus. – ClockworkSoul 03:13, 20 January 2009 (UTC)

abbreviation for the word molecules that is different from mol or moles

I am looking for an abbreviation for the word molecules, that is not similar to words like "mol" or "mole" (as in a mole of substance, 6e23 things) —Preceding unsigned comment added by Cinnamon colbert (talk • contribs) 22:58, 19 January 2009 (UTC)

Do I read your question correctly: You are looking for an abbreviation for the word molecule that can not be mistaken for the SI unit mole or the corresponding sign mol? Not sure there is such a thing. [7] The dot could be used to tell one from the other, but that leaves a lot to be desired. 76.97.245.5 (talk) 00:40, 20 January 2009 (UTC)

The trouble is that there really isn't a synonym for the word 'molecule' - so any abbreviation is more or less going to have to be something like 'mol'. So I think you're kinda stuck. SteveBaker (talk) 03:15, 20 January 2009 (UTC)

Actually, the abbreviation for molecule is mole, which makes sense because that's what a mole is: lots and lots of molecules. Since you seem to want to smaller version of it, we can just work some SI magic: since 1 mole = 6.02x10²³ molecules, 1 molecule would be about 60 yoctomoles (ymol), and 60,200 zeptomoles (zmol). Will that do? – ClockworkSoul 08:21, 20 January 2009 (UTC)

Are you sure about that? I get 1 molecule = 1.66 yoctomol... Someone42 (talk) 09:36, 20 January 2009 (UTC)

Hmm... I was wrong, but it's not 1.66 ymol either: (6.02e23 molecules/mole)(1 mole/1e24 ymol) = (6.02e23 molecules/1e24 ymol) = .602 molecules/ymol (and 602 molecules/zmol). I really should remember not to try to do simple arithmetic so late at night. – ClockworkSoul 18:03, 20 January 2009 (UTC)

Yes, there are .602 molecules in a yoctomol, so 1 molecule is 1.66 ymol, as Someone42 said. Algebraist 18:12, 20 January 2009 (UTC)

Doh, thanks. Here's a query for the ref desk: what's wrong with me today? – ClockworkSoul 20:52, 20 January 2009 (UTC)

Have you been spending too much time in Australia lately? --Tango (talk) 22:22, 20 January 2009 (UTC)

That took me a second. Brilliant, Tango! – ClockworkSoul 00:36, 21 January 2009 (UTC)

How about 'cule? — DanielLC 18:18, 21 January 2009 (UTC)