Science desk
< May 27	<< Apr \| May \| Jun >>	May 29 >

Welcome to the Wikipedia Science Reference Desk Archives
The page you are currently viewing is an archive page. While you can leave answers for any questions shown below, please ask new questions on one of the current reference desk pages.

May 28[edit]

X:A ratio[edit]

The X:A ratio articles defines the X:A ratio as the ratio "between the X chromosome and the number of sets of autosomes in an organism."

But an X chromosome is not a number. Does the article mean "number of X chromosomes"? But an organism has either one or two X chromosomes... 65.92.7.8 (talk) 01:45, 28 May 2014 (UTC)[reply]

Fruit flies can have three... 24.5.122.13 (talk) 02:02, 28 May 2014 (UTC)[reply]

Yes, the article means "...number of...", so I just now clarified the article. And although it's uncommon, humans can also have more than two X chromosomes; see Aneuploidy#Types. Red Act (talk) 02:20, 28 May 2014 (UTC)[reply]

Okay, thanks. 65.92.7.8 (talk) 03:06, 28 May 2014 (UTC)[reply]

Radiation exposure[edit]

How do I go from roentgens to Sieverts? Thanks in advance! 24.5.122.13 (talk) 07:34, 28 May 2014 (UTC)[reply]

One sievert equals 100 rem. per the Sieverts article you linked. it also states it here. Richard-of-Earth (talk) 08:44, 28 May 2014 (UTC)[reply]

Note that one roentgen (R) is not the same thing as one rem. In practice, they're often fairly close for x-rays, but typically 1 R of x-rays is a bit less than 1 rem of equivalent dose. Roentgens are a measure of ionization in air whereas the rem or the sievert are (different) measures of equivalent or effective dose in a biological system. TenOfAllTrades(talk) 11:36, 28 May 2014 (UTC)[reply]

So how do I convert from roentgens to rems? 24.5.122.13 (talk) 23:15, 28 May 2014 (UTC)[reply]

To go from roentgen to gray you use F-factor (conversion factor) and to go from gray to sievert (rem) you use Radiation weighting factor (Q factor). Maybe Absorbed dose is worth reading. Thincat (talk) 11:16, 29 May 2014 (UTC)[reply]

Thanks! 24.5.122.13 (talk) 20:10, 29 May 2014 (UTC)[reply]

Down's Syndrome and obesity[edit]

Do we know why Down's causes obesity ? See Down_syndrome#Physical, if you don't believe that it does. I suppose one possibility is that it's merely mental. That is, while normal intelligence individuals know what they must do to maintain a low weight (eat right and exercise), Down's patients do not. Perhaps Down's patients are also less motivated to do so. Are these the only reasons, or is there a physical cause ? (I know that Down's patients tend to be shorter, but that doesn't automatically bring obesity with it.) StuRat (talk) 11:43, 28 May 2014 (UTC)[reply]

I found Obesity in Children with Down Syndrome: Background and Recommendations for Management which says: "Although specific associated problems of Down syndrome, both physiological and behavioral, foster the development of obesity..." (on the second page). Alansplodge (talk) 12:40, 28 May 2014 (UTC)[reply]

"Down's patients"? That is an insulting and thoughtless phrase. I have no idea how you treat people who have Down's syndrome in the USA but here in the UK they are individuals mostly integrated into the community and not regarded as 'patients' by anyone. The idea that if you know you must eat less and exercise to stay slim is well known by most obese people but they still don't. Richard Avery (talk) 06:32, 29 May 2014 (UTC)[reply]

I have no idea what ~~your~~ you're on about now. Down's Syndrome is a medical condition, therefore anyone with a medical condition can be accurately called a patient. Not even sure what term you would use instead.

And obviously Down's Syndrome is not the sole cause of obesity, so that comment is rather useless, too. StuRat (talk) 15:09, 29 May 2014 (UTC)[reply]

(Shakes head sadly) Richard Avery (talk) 08:01, 30 May 2014 (UTC)[reply]

A patient is any recipient of health care services. Down syndrome patients are afflicted by a genetic disorder that is incurable. Ongoing improvements in health care has increased their life expectancy from 12 years in 1912 to 50-60 years in the 2000s. Charity and advocacy organisations exist for Down's patients in the UK and in the US that you may contact if you really wish to help. Down's patients are not helped by admonitions about PC wordage. That seems to be what you're (not "your") headshaking about. 84.209.89.214 (talk) 19:38, 30 May 2014 (UTC)[reply]

Thanks, and I corrected that typo. StuRat (talk) 05:34, 31 May 2014 (UTC)[reply]

Why were the stellar nursery clouds spinning in the first place?[edit]

My understanding is that stellar systems of stars (at least the current "generation") with planets orbiting them started out as clouds of dust ("dust" being a catch-all word for the matter that came from dying stars) which eventually collected due to gravitational forces until the internal forces of the accreted blob were enough to cause fusion to start, and of the matter that spewed out after the sun "started", planets accreted. Of course this is a very simplified summary by me. My question is what causes those initial clouds and subsequently accretions destined to be stars to be rotating in the first place? 75.75.42.89 (talk) 18:04, 28 May 2014 (UTC)[reply]

A very small initial rotation turns into a much greater rotational speed, as the cloud collapses, due to conservation of angular momentum, just as an ice skater spins faster as she brings her arms in. As for the source of that initial rotation, there's the rotation of the galaxy, and that in turn came from the gravitational interaction with nearby galaxies, I suppose, as they were forming. How any rotation at all started comes down to the problem of why matter was unevenly distributed initially in the universe, and had different relative velocities. To that, we have no answer. StuRat (talk) 18:10, 28 May 2014 (UTC)[reply]

"To that, we have no answer" In fact we do. During the first extremely small fraction of the second after the Big Bang the world was so small that quantum fluctuations affected this super fluid (my term, sorry). Those quantum fluctuations which may be observed now in some artificial conditions led to unequal matter density in the early universe and subsequently resulted in gravitational galaxies formation. --AboutFace 22 (talk) 21:18, 28 May 2014 (UTC)[reply]

And what causes the quantum fluctuations ? StuRat (talk) 03:57, 29 May 2014 (UTC)[reply]

Quantum fluctuations are an intrinsic part of the universe (according to modern quantum field theory), and are essentially a direct consequence of the uncertainty principle. The underlying physical processes are believed to depend upon probabilistic effects and hence have an intrinsic degree of randomness. These effects are generally negligible on the macroscopic scale, but are important on very small scales. However, inflation made small things very large very quickly and carried and imprint of the quantum fluctuations with it. Dragons flight (talk) 04:35, 29 May 2014 (UTC)[reply]

Why would the nursery clouds not be spinning in the first place? Zero is just another number, and any little nudge from a nearby supernova would make a non-rotating system rotate. --Bowlhover (talk) 05:16, 29 May 2014 (UTC)[reply]

Under Occam's Razor, zero is simpler. For example, having zero whales in you back yard is a lot more logical than any other number. StuRat (talk) 14:53, 29 May 2014 (UTC)[reply]

You're missing the point. In space, a spinning object will continue to spin due to lack of friction. Any little nudge from supernovae, gravitational interactions, collisions, radiation pressure, and the like will make an object spin. In order for an object to not be spinning, the millions of torques that it has ever encountered must EXACTLY cancel out. That is virtually impossible in a complicated universe. --Bowlhover (talk) 16:44, 29 May 2014 (UTC)[reply]

Once we assume there was a non-uniform distribution of matter in the initial universe, then yes, spinning is a natural result of that. It's that non-uniform distribution which is the oddity. StuRat (talk) 13:50, 30 May 2014 (UTC)[reply]

Bowlhover has a good point. The chance of throwing a dart at a real number line and hitting zero is zero. Assuming zero is most certainly not simpler than assuming non-zero. SemanticMantis (talk) 15:24, 29 May 2014 (UTC)[reply]

One galaxy might have rotational momentum or energy in one direction that is balanced by that of others, such that over a large enough scale (or over the universe) it sums to zero. Edison (talk) 20:11, 29 May 2014 (UTC)[reply]

The thing is that if the universe started from a literal singularity (a point of zero size) then from an argument of symmetry, then in 'classical' physics, everything that follows should produce a universe that's perfectly uniform in every direction...and there could be no rotation whatever because that would be an asymmetrical thing - and no initial source of asymmetry is possible.

We really need some random quantum-type effects to break up the perfect symmetry and allow the statistics of that randomness to generate asymmetry. Once you have a breaking of that perfect uniformity - however tiny - then chaos theory can produce all manner of complicated motion and clumping.

SteveBaker (talk) 15:58, 30 May 2014 (UTC)[reply]

Whatever the sources may be of initial non-uniformity, energy and angular momentum in a hypothetical initial universe they manifested in a F.O.P. once-only event. A bell cannot be un-rung; every event that follows, including you reading this, is F.O.P. uniquely predetermined by that primordial event. I suggest that the Predeterminism implicit in the prevailing Big Bang cosmological model is inseparable F.O.P. from conscious or unconscious dependence on a metaphysical causation, while less dogmatic steady-state and Multiverse world views provide more fertile scopes for human intellectual development and expression. F.O.P. = from our perspective. 84.209.89.214 (talk) 18:39, 30 May 2014 (UTC)[reply]

Native aluminum[edit]

There is an old story from Pliny's Historia Naturalis about what some sources suggest was an aluminum goblet given to Tiberius: "One day a goldsmith in Rome was allowed to show the Emperor Tiberius a dinner plate of a new metal. The plate was very light, and almost as bright as silver. The goldsmith told the Emperor that he had made the metal from plain clay. He also assured the Emperor that only he, himself, and the Gods knew how to produce this metal from clay. The Emperor became very interested, and as a financial expert he was also a little concerned. The Emperor felt immediately, however, that all his treasures of gold and silver would decline in value if people started to produce this bright metal of clay. Therefore, instead of giving the goldsmith the regard expected, he ordered him to be beheaded." ^[1]

However, a recent translation I searched tells this a very different way: "There is a story that in the reign of Tiberius there was invented a method of blending glass so as to render it flexible. The artist's workshop was completely destroyed for fear that the value of metals such as copper, silver and gold would otherwise be lowered. Such is the story, which, however, has for a long period been current through frequent repetition rather than authentic."^[2] A forum I stumbled across cites some similar glass-based variants of the story.^[3]

Now I can't account for the differences in translation, which is something more worth asking at Humanities, but the preceding forum provided another interesting reference to native aluminum in the "Nanjing Belt".^[4] Apparently an ancient belt was found to contain twenty pieces of metal, including four that turned out to be aluminum; it doesn't sound like fraud is clearly ruled out but it wasn't proven either.

More interesting is that not only is there this artifact, but actual native aluminum has been reported to have been found in China. We cover this a bit at Aluminium, but to add some other references, a tungsten-gold deposit in Lianhuashan^[5] and volcanic rocks, hydrothermal deposits, and in ocean sediments in tectonically active areas.^[6] (our article mentions cold seeps) Apparently though some identifications have been in error, due to aluminum wrappings for explosives in mining?^[7] According to [8], " there are three models of the formation of native aluminium, such as carbon deoxidization in the high temperature environment, endogenous processes of high hydrothermal activity in the submarine hydrothermal fluids, element replacement amond Al,S,K,Na." However, our article on aluminum mentions another, the biological reduction of Al(OH)4-.

Now to put together a highly speculative model, I would suppose it should be possible for some people, perhaps in Guangdong, to find some placer deposits with aluminum grains and try smelting or glassmaking from them at high temperatures (higher than known to be used at that period, it would seem) and end up with small amounts of apparently precious metal. Seeking a wealthy novelty market, these could have been traded far and wide, to the Wu capital in Nanjing and even down the Silk Road to the Romans. Tiberius' reaction might be accounted for not as a matter of suppressing technology, but because practically any piece of aluminum coming out of the Silk Road would have been traded hand to hand, gradually rising up the Roman hierarchy until it came to him... putting the "inventor" in a bad spot when his piece wasn't the first. (Either that or he turned it over and spotted the "Made In China" on the back :) The industry might have plausibly collapsed and the technology forgotten once the best known deposits were worked out, since without a clear scientific appreciation of the elements as Napoleon III had, its value might have been limited to something near the value of silver no matter how expensive heating mountains of sediment became.

Anyway, my question here is: can people recommend some more data to suggest that native aluminum was available to Chinese from 100BC-300AD, that they were capable of working it, that other aluminum artifacts than these two fringey cases exist? I realize that right now this is still at about a "paranormal" level of evidence, and yet... how often have the ancients ever turned out to have been less than what we expected? Wnt (talk) 19:22, 28 May 2014 (UTC)[reply]

The credibility of this report of an ancient aluminium gear piece in Russia is not helped by using a photograph twice as mirror images. A link fallen from a watch strap perhaps? 84.209.89.214 (talk) 20:00, 28 May 2014 (UTC)[reply]

Aluminum is highly susceptible to oxidation by air, so any significant deposits of native aluminum are highly unlikely -- it would oxidize as fast as it forms. The version with the glass is more likely -- this could have been done simply by adding borax (which was readily available in the Roman Empire) to the molten glass to make essentially a variety of Pyrex glass. 24.5.122.13 (talk) 23:24, 28 May 2014 (UTC)[reply]

To be clear, our article on aluminum does currently credit reports of native aluminum granules. Gears, of course, are another story (I expect something interesting but not that interesting involving explosives or drilling). Wnt (talk) 02:08, 29 May 2014 (UTC)[reply]

What the typical man's and woman's voices sound like. Disagree?[edit]

Sometimes, there are people who say a particular person doesn't sound like the typical man/woman when he/she talks. But we need to know what is considered the typical man's/woman's voice.

I believe the voice of Douglas Rain (the narrator heard in the video below) is what's considered the typical man's voice:

http://www.youtube.com/watch?app=des...&v=pkx86BbAvsM

I believe the voice of Majel Barrett (yes, the dark haired woman in the video below) is what's considered the typical woman's voice:

http://www.youtube.com/watch?v=YuodlFsfosA

To make it simple: The typical man sounds like Douglas Rain. The typical woman sounds like Majel Barrett.

Anyone disagree with this? Stoned stoner (talk) 21:31, 28 May 2014 (UTC)[reply]

What's your basis for this assumption? ←Baseball Bugs ^{What's up, Doc?} carrots→ 21:33, 28 May 2014 (UTC)[reply]

Well, people largely associate female computer voices with Majel Barret and male computer voices with Douglas Rain. Stoned stoner (talk) 21:42, 28 May 2014 (UTC)[reply]

Who says that? ←Baseball Bugs ^{What's up, Doc?} carrots→ 00:16, 29 May 2014 (UTC)[reply]

A google search shows that when people bring up examples of male and female computer voices, it is HAL (the computer voiced by Douglas Rain in 2001: A Space Odyssey (1968)), and the the starship Enterprise's computer (voiced by Majel Barrett) in Star Trek (1966-1969), that are most frequently given examples. — Preceding unsigned comment added by Stoned stoner (talk • contribs) 00:33, 29 May 2014 (UTC)[reply]

They probably bring up HAL because it's familiar. You didn't initially ask about computer voices, just voices in general. I always thought HAL sounded too breathy for a normal male voice. A typical male TV newscaster would work better. ←Baseball Bugs ^{What's up, Doc?} carrots→ 02:20, 29 May 2014 (UTC)[reply]

The Ref. Desk should not be used to convass opinions. Boys and girls have roughly similar vocal pitch, but during puberty the male voice typically undergoes a downward Voice change (see article). Voice therapy (trans)#Differences between male and female voices analyses their pitches and resonances. This study explains the differing ways the brain interprets male and female voices. 84.209.89.214 (talk) 00:30, 29 May 2014 (UTC)[reply]

Yes, a statement followed by "anyone disagree?" isn't a great way to approach us. If you'd like a reference on vocal typicality, I suggest this freely-accessible article titled "Vocal Attractiveness Increases by Averaging" [9]. It even has examples of averaged voices, you can ask at WP:REX if you're having trouble getting access. They might even sound to you like your examples. The point is, averaging voices is a scientific notion of typicality that has been studied. You might also be interested in the analogous research on averaged faces, some of which is summarized here: [[10]]. Perhaps someone has done research where participants are asked to rank vocal samples in terms of typicality, you might be able to dig something like that up on google scholar. ( As for your claim: it's ill-defined and poorly scoped, to the extent that I can't even disagree ;) SemanticMantis (talk) 02:23, 29 May 2014 (UTC)[reply]

"Vocal Attractiveness Increases by Averaging" was an interesting read. Thanks, Mantis, for the link. It left me wondering, however, whether "vocal attractiveness" would be judged differently by people of different cultures (I imagine it would). The article didn't mention in the methodology section if the "listeners" represented a cross section of world cultures or if they were all from Western cultures. I once heard a Southeast Asian man praising the voice of a particular Thai actress as "beautiful" and "most pleasing", but to me her voice sounded so high pitched and nasal as to be almost annoying. "Typical" men's and women's voices and their level of perceived attractiveness probably varies significantly by culture. Odd that I can't find, through an admittedly hasty search, any papers on that aspect of the topic.--William Thweatt ^Talk^Contribs 03:38, 29 May 2014 (UTC)[reply]

This whole situation sounds somewhat comparable to the Theory of Forms, the Platonic concept of ideals. Probably everyone has an idea of what the typical man or woman sounds like, and probably everyone's idea is slightly different from everyone else's; this isn't something that can be quantified or measured. Nyttend (talk) 04:03, 29 May 2014 (UTC)[reply]

I beg to differ. Stoned stoner (talk) 05:01, 29 May 2014 (UTC)[reply]

You have my permission: go ahead and differ. —Tamfang (talk) 16:45, 29 May 2014 (UTC)[reply]

Agreed that there will likely be cultural norms that influence how voices are perceived. My impression was that e.g. Anglophone listeners would rank averaged native-Anglophone voices as more attractive than "raw" single native Anglophone voices, and likewise for other groups listening to averages of people within their groups, be they political, ethnic, linguistic, etc. I also disagree with Nyttend that this cannot be quantified or measured. I do agree that it is difficult to study these ideas with rigorous methods and get repeatable results. Social psychology and sociolinguistics deal with this kind of vagueness all the time. That the study is difficult is no reason not to engage! SemanticMantis (talk) 15:20, 29 May 2014 (UTC)[reply]

Any question worded like "Do you agree?" could be answered with a simple "Yes" or "No". ←Baseball Bugs ^{What's up, Doc?} carrots→ 14:18, 30 May 2014 (UTC)[reply]

@Baseball Bugs: (off-topic but I think this is interesting stuff) I think that's only true for well-defined, clear claims of fact. E.g. "All swans are white -- do you agree?" I can't in good faith agree or disagree with the OP's claim. See e.g. not even wrong for the idea I'm going for. Also perhaps loaded question. For example "Bill has stopped beating his wife -- do you agree?" Whether you answer "yes" or "no", it implies wife beating occurred in the past, and a simple yes/no answer will not suffice, if we want to be fair to Bill. SemanticMantis (talk) 15:25, 30 May 2014 (UTC)[reply]

Ah, good point. Hence the need for a third possible response: "No opinion". As you and others have indicated, there could be studies or surveys on the subject - but even that still really comes down to individual opinions. My GPS has some type of computerized male voice that sounds exactly like the computerized male voice on NOAA weather radio, and would never be mistaken for the voice of HAL, but somebody somewhere decided that that sounds like a proper male voice, at least for those applications. As to a woman's voice, I'd have to say that the female voice they use on NOAA is kind of similar to Majel Barrett's computer voice, except they've added inflection to the voice so it sounds more "normal" than the Star Trek computer's deliberately monotonic voice (which sounds very dated by today's standards). The recorded female voice you often hear on telephone answering systems often seems to be the same woman (which it might well be) - and I'm pretty sure it's not Majel Barrett. In fact, it's more like a female version of HAL's soft but clear enunciation. ←Baseball Bugs ^{What's up, Doc?} carrots→ 15:57, 30 May 2014 (UTC)[reply]