Wikipedia:Reference desk/Archives/Science/2007 November 9

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.

November 9

Robinson projection

I'm beating my head against the wall. I want to come up with a simple script that will convert latitude and longitude coordinates to x,y coordinates on a given map in a Robinson projection of a given width with a given central meridian. Ideally this would be done in Actionscript but if I had it in any sort of code or pseudocode that would be fine (which is why I am asking here and not the computing desk—it is not a computational difficulty, it is a conceptual one. Once I have an idea of what I should be doing conceptually it will be trivial to code it).

There are a few map projection projects out there but they are all extremely complicated since they are designed for exporting ALL projections; I _just_ want Robinson. I've read the article and I grok that it's about a lookup table but I still have no idea how I'm supposed to convert that table into x,y coordinates with a given map.

Can anybody help? I just want instructions on the level of "take your number from column one, multiply it by something in column two, then do something else, do something with the central meridian and the width, and presto-chango you have x and y coordinates." I'm having trouble figuring out how to use the table. --140.247.10.141 00:18, 9 November 2007 (UTC)

The general method will be to get a formula that maps the points from one projection to the other. THen you invert the formula so that it maps the points in the reverse direction. Then scan all the points on your new map, say from top left to right and then going down in a raster pattern, use the formula to get a new coordinate to look up the original map. If the coordinates are on the map copy the pixel. If its off the map stick in a "missing data " colour - perhaps white or blue. Graeme Bartlett 01:19, 9 November 2007 (UTC)

Graeme, A Robinson projection is not a formula driven mapping.

Matlab code snippet

robval = [
00 1.0000 0.0000 
05 0.9986 0.0620 
10 0.9954 0.1240 
15 0.9900 0.1860 
20 0.9822 0.2480 
25 0.9730 0.3100 
30 0.9600 0.3720 
35 0.9427 0.4340 
40 0.9216 0.4958 
45 0.8962 0.5571 
50 0.8679 0.6176 
55 0.8350 0.6769 
60 0.7986 0.7346 
65 0.7597 0.7903 
70 0.7186 0.8435 
75 0.6732 0.8936 
80 0.6213 0.9394 
85 0.5722 0.9761 
90 0.5322 1.0000 
];

robval(:,3) = robval(:,3) * 0.5072;
robval = [robval(end:-1:2,:);robval(1:end,:)];
robval(1:90/5,[1,3]) = -robval(1:90/5,[1,3]);

rvals2 = interp1(robval(:,1),robval(:,2),latitude,'cubic');
rvals3 = interp1(robval(:,1),robval(:,3),latitude,'cubic');
y = -rvals3;
x = rvals2/2.*longitude/180*2;

The above is taken from a Matlab program I wrote to generate a Robinson projection. Dragons flight 01:35, 9 November 2007 (UTC)

does it use cubic interpolation? the article does not say what kind of interpolation is used. Graeme Bartlett 01:44, 9 November 2007 (UTC)

My quick search didn't turn up specifics on the kind of interpolation (other than the phrase "simple interpolation method"), but this page shows an example Robinson map with a caption saying "...calculated with 3rd degree polynomial interpolation", for what it is worth. Pfly 06:29, 9 November 2007 (UTC)

That looks like it is in the right ballpark. Here I admit to not being able to follow MatLab's syntax with dealing with Arrays. Could someone convert it into something a little more standard, or just pseudocode? I feel like I'm on the cusp of having it but researching how MatLab deals with Arrays is something I'm not very excited about... --140.247.11.32 16:09, 9 November 2007 (UTC)

Muteness

If you're born mute due to brain damage rather than throat/vocal cord damage, as an infant, do you still cry? Assuming you can hear, what happens when you learn to understand language? Do you merely stop crying but not be able to communicate until someone teaches you sign language? In fact, is it even possible to be mute but not deaf as a result of brain damage? Or would it have to be throat/mouth damage? Kuronue | Talk 02:06, 9 November 2007 (UTC)

I'm not sure about the physiology of crying (there is no article on crying here, unfortunately), but it seems to be associated with contraction of the diaphragm, and should occur with or without vocal chords or vocalization control. Children can hear their own voices, and it's an extremely important part of their personal language development, so a mute child will probably have to learn some sort of gesture or sign language to compensate, and if one isn't taught, it will probably imitate or invent such a language from what it perceives from others (gestures, etc). Unfortunately the pages here for muteness and aphonia are also lacking. Brain damage can cause muteness if the damage is significant enough to somewhere such as Broca's area, which would affect speech production, though it would damage a lot of other linguistic abilities as well such that someone with such damage may not be able to perform sign language. A much more mild damage would be from, say, damaging one of the facial nerves that control the mouth and tongue, which would easily destroy comprehensible speech. Finally, of course, a laryngectomy of the sort that Steven Hawking went through would destroy vocalization completely. SamuelRiv 06:10, 9 November 2007 (UTC)

No other responses, huh? Why is it that there's so little information? I meant mostly the verbal part of crying - if the vocal cords function but the bit of the speech center that organizes sound into speech does not, I'd think the infant would scream but then... would the child merely become silent around 2-3 years of age when others learn to speak? Also, good point, if it's brain damage to the Broca's Area or similar, he might not be able to learn sign language... *ponders* Maybe I'm making this too hard for myself. The character I'm writing is a young boy of about 6 who cannot speak, but I want him to be able to respond to the telepathy, and he's not visibly deformed - I was going to go for some sort of umbilical-cord oxygen-deprivation at birth scenario. I oughta just have his vocal cords themselves be malformed due to mutated genes or something... Kuronue | Talk 17:06, 13 November 2007 (UTC)

asbestos -microencapsulization healing?

Once fibers get in the lung, they can't be removed., sometimes leading to cancer. When re-modeling a house, asbestos that can't be removed is encapsulated with an impenetrable material. Why can't micro-encapsulization, biological or chemical, be used likewise to neutralize fibers in situ? Wiki articles on microen. and on 'self-healing' were good. Comments? —Preceding unsigned comment added by 76.182.3.188 (talk) 02:11, 9 November 2007 (UTC)

Well, microencapsulation wouldn't remove the actual foreign particle from the lung, which I believe (not my field at all) is the primary cause of the cancer in the first place. See carcinogen. Aside from that, encapsulating the fibres should be feasible with molecules attracted the long mineral, but I'm not sure of any such engineering out there for individual strands. SamuelRiv 06:15, 9 November 2007 (UTC)

Exactly. One of the things that asbestos does (Asbestosis) happens because the particles are essentially impenetrable. The lung detects the presence of the foreign particle, triggering an immune response. Essentially it releases some localized acid to try to dissolve the particle, which does not work on the asbestos particle, but over time does start to dissolve lung tissue. Coating the asbestos in some other impenetrable shell would likely result in the same thing, unless you could use something invisible to the immune system and non-irritating to the tissues to avoid that response. Not medical advice! Arakunem^Talk 15:53, 9 November 2007 (UTC)

Time

• Will time "be faster" if an event caused the Earth to rotate faster? (and vice versa)
• Does the moon going farther out from the Earth affect the rotation of the Earth?
• Also, could this be happening now?

Time recently has been going by so freaking fast. I worship seconds now. 67.35.94.120 02:27, 9 November 2007 (UTC)

No, No, Yes. Time wouldn't change if the earth rotated faster - the length of a day would get shorter - but the definition of a second (and therefore a minute and an hour) is defined by the rate of some atomic event or other...something that will never change. The orbit of the moon doesn't significantly affect the rotation of the earth - although doubtless there is some small effect or other. The moon is most definitely gradually moving away from the earth - but not at a rate that you could possibly notice even over many human generations. Sadly, your subjective rate of time flow is something we can't do much about - but it is entirely subjective. SteveBaker 02:39, 9 November 2007 (UTC)

Actually tidal drag caused by the moon is the primary effect slowing the rotation of the Earth and is directly linked to the growth in the moon's orbit. It is still a very small effect though. Dragons flight 03:01, 9 November 2007 (UTC)

(ec) Angular momentum is transferring from the spinning earth to the moon's revolution about the earth by a mechanism involving the tides. As the moon moves away, the earth is slowing down. Yes this is happening now. This causes the day to get longer, but the effect is small. We now must add about one second per year to keep the clocks and synchronized with the earth's rotation: see leap second. -Arch dude 02:41, 9 November 2007 (UTC)

Actually, when I read the question I assumed anon was referring to special relativity effects of reduction in relative velocity to the perception of time. The centripetal acceleration that we feel makes the calculation non-trivial, but in general our time would be "slower" than that of an observer stationary relative to our rotation. SamuelRiv 03:38, 9 November 2007 (UTC)

(By a negligable amount...yes) The point is that while there are such effects, they are all quite utterly negligable compared to human timescales. Our OP is claiming that time is going by faster than it used to within his/her lifetime...that's simple not true to any measurable degree no matter what complicated science you try to throw at it. The effect of the moon, the effect of relativity - these are all UTTERLY negligable - and it is wrong to suggest otherwise just because we can. The clear answer to the OP's question is "No". SteveBaker 14:11, 9 November 2007 (UTC)

absorption refrigerator

Look at this http://www.nh3tech.org/abs.html

Since absorption refrigerator uses heat to chill things down and since CPU generates a hot of heat. Why isn't absorption refrigerator uses the CPU heat to cool down hot CPUs? 202.168.50.40 04:15, 9 November 2007 (UTC)

Expense, complexity, and environmental hazards. Basically the first two are the same reason computers don't come standard with liquid cooling. Air cooling is by far the simplest, cheapest, and safest answer for most processors. SamuelRiv 04:25, 9 November 2007 (UTC)

Another reason is that you can't use the heat from the thing you're trying to cool as the energy source for the system. If you cool the CPU, it won't be hot, so it won't be able to boil off the ammonia, so the CPU will heat up until you cool it again, at which point it won't be hot...you get the idea. And you don't want the CPU to be hot enough to power the system in the first place. I remember learning about the ammonia system when I was tutoring my landlord's kid. It's a fascinating machine. It's one of those inventions that is NOT obvious once someone's done it the way the cat door is. --Milkbreath 14:16, 9 November 2007 (UTC)

paleontology & neuroscience

If the brain of a dinosaur or other prehistoric organism were discovered, perfectly preserved so as to be in the same state as moments after its death, what facts about its behaviour, intelligence, memory capacity, etc. would neuroscientists & paleontologist be able to confidently infer from the brain & nothing else.

Hypothetically-speaking; please disregard whether such a brain could possibly be found in reality. 3170s228 04:42, 9 November 2007 (UTC)

From the perspective of neuroanatomy, an awful lot. From a cognitive perspective, next to nothing. Animal brains (which I know nothing about) are a lot different from human brains, but in general we could find out most innervation and structure of the brain, which would tell us quite a bit about a variety of processing abilities. Intelligence is usually measured in terms of cerebrum size, so we'd have an estimate of that. We may be able to infer some things about memory if limbic structures are present, including the apparent structure of long-term memory and perhaps even its synaptic plasticity. With present understanding, however, we could infer next to nothing about behavior - I don't see any real viable correlation of brain structure to behavior in a class of animals like reptiles. SamuelRiv 05:33, 9 November 2007 (UTC)

Animals tend to have similar brain parts. Knowing the existence and relative sizes of different parts of the brain can tell you a lot. They hardly need a perfectly preserved brain. The cavity in a fossilised skill would do. I remember seeing something where they showed that the brain of some kind of dinosaur was similar to that of an alligator and that it probably behaved like one. — Daniel 01:29, 10 November 2007 (UTC)

How would one find out about the kind of society of prehistoric humans?

How would someone find out about the kind of society that existed among prehistoric humans 50,000 years ago? I am not asking what the answer actually is but rather how you would find the information. I do not mean by like research but how would like scientists find out this information. Any help would be appreciated. —Preceding unsigned comment added by 69.181.131.67 (talk) 05:16, 9 November 2007 (UTC)

Great question! As you might guess, information about the social structure 50,000 years ago will be fairly limited. What kind of inference you make will be based on whatever physical evidence is preserved. By examining what kind of tools they had, and what wear was associated with them, along with bones or other trace detritus, it may be possible to guess at what they ate (some other techniques, such as Isotope analysis also can be telling in this regard). Sometimes human skeletal remains can give clues about how the person lived, although this is tricky at long ages. Occasionally a glimpse of the "soft culture" is given; One (Neanderthal) skeleton recovered from the Shanidar site indicates injury and healing. A reasonable guess, since he would have been unable to fend for himself, is that he was cared for by his companions. Was there a specific question which prompted the interest? --TeaDrinker 05:37, 9 November 2007 (UTC)

Note bones also tell about religious practices and superstitions. Garbage (discarded bones of killed animals tell what they hunted and how) and housing are other important finds. Then one can look at probable migration patterns or recorded history to see where that society went: if a descendant society still exists, one could learn a lot from examining them and their own perception of history. Linguistic history of any kind could almost certainly not be traced that far back, unfortunately. SamuelRiv 05:41, 9 November 2007 (UTC)

An overly broad and probably not very helpful answer: Look at the archaeological record and, using everything we know in modern science (particularly medicine) and current cultures with deep roots, make some "educated" guesses. --Bennybp 07:38, 9 November 2007 (UTC)

• A while back they did a reconstruction in Germany. Build a prehistoric village and have people live there in the way the prehistoric people did. They're interactions changed significantly from what they were used to in modern life. You can Google on SWR and "Das Steinzeit Experiment". - 131.211.175.100 12:26, 9 November 2007 (UTC)

First Solar

According to this

According to Deutsche Bank analyst Steve O’Rourke, the company’s results came in well ahead of expectations as its German production facility ramped ahead of schedule, and incremental improvements in efficiency, production throughput, and currency exchange rates drove panel cost per watt to a new low of $1.19

Does that mean I can buy a 65 watt solar panel from First Solar for only $78 dollars???

5kW worth of Solar Panels for only $6000 + installation cost?

220.237.184.66 06:14, 9 November 2007 (UTC)

Well, perhaps - but maybe they don't make them in 65W sizes. You are assuming that this is the cost of a complete unit that you can bolt onto the roof of your house (or whatever) and use - that may not be the case. I suspect they are talking about the raw silicon wafers - it may cost considerably more to assemble them into weatherproof units, add controller electronics, etc. Is that the retail cost or the wholesale cost - if you're going through a middle-man, it could be more. In short, no, it doesn't necessarily mean that...although it might. SteveBaker 14:03, 9 November 2007 (UTC)

gryroscopes

Can two gyroscopes spinning in opposite directions counteract each other? —Preceding unsigned comment added by 204.251.179.61 (talk) 07:05, 9 November 2007 (UTC)

Sure. Why not? It all depends on what you mean by "counteract". -- kainaw™ 13:17, 9 November 2007 (UTC)

From my interpretation of the question, it seems you're asking if two gyroscopes in the same system but spinning on different axes and otherwise not interacting counteract, and the answer is yes and no. No in the sense that they both will resist changes in their absolute spin axis to conserve angular momentum, so they will still keep an object on a stable trajectory. However, a single gyroscope can have its system rotated about the gyroscope's axis without problem, so you need a second gyroscope in a different direction to restrict all rotation. In this way, they do have an interaction effect. SamuelRiv 13:56, 9 November 2007 (UTC)

If they are bolted together then as you try to turn them, each gyro will exert a force onto their common framework - the resultant force will apply. It's no different than if you bolted two cars together and tried to steer them in opposite directions. Gyroscopes (like magnets) have taken on a mystery that they don't truly deserve. SteveBaker 13:59, 9 November 2007 (UTC)

Man, magnets are really, really awesome, and do deserve every bit of mystery that they're given! Invisible forces! Immense power in tiny pieces of metal! Wow! I'm still amazed by magnets, they're the closest thing to magic that I interact with on a daily basis! --24.147.86.187 21:25, 9 November 2007 (UTC)

I dunno - gyroscopes are pretty weird too. Take the front wheel off your bicycle, hold it by the axles and sit in a swivel chair - now have someone spin the wheel up as fast as they can get it to go - then tilt the wheel back and forth...tell me that ain't freaky on the scale that magnets are. But you're wrong about the magnets having "immense power" - they don't store any energy in the form of some kind of "magnetic power" in the way that (say) a battery stores electrical energy. SteveBaker 21:52, 9 November 2007 (UTC)

All I really mean by "immense power" is "electromagnetic forces are so much more powerful (on small scales) than gravitational ones, which is awesome to think about. A magnet can totally kick earth's ass when it comes to attracting a piece of metal." --24.147.86.187 06:04, 14 November 2007 (UTC)

As a related question, if you've got a sealed box containing two counter-rotating coaxial flywheels, is there any measurement you can do to tell if the flywheels are rotating or not? How about if the axises of rotation are parallel but not co-linear? --Carnildo 21:43, 9 November 2007 (UTC)

So it won't matter if the axes of rotation are not collinear at all. You can translate your whole spinning system arbitrarily and nothing will change. The angular momentum vectors of the two flywheels won't cancel - both will resist angular momentum changes of their respective systems. So if you turn the box, you will feel twice as much restorative force from the conservation of ang mom as if you only had one flywheel, whether or not they're spinning in the same direction. SamuelRiv 23:38, 9 November 2007 (UTC)

This problem is a little more subtle than first meets the eye. The behavior of a gyroscope is normally just governed by the conservation of angular momentum. However, if you have two identical rotors with collinear axes in one rigid frame, rotating with equal speeds in opposite directions, the angular momentum of the two rotors cancel out, and the net angular momentum of the system is zero. So it would appear at first glance that you should be able to rotate the system as easily as any other object with the same moment of inertia, since there is no net angular momentum to be conserved. If you apply a torque to the system, the precessions due to the two rotors are in opposite directions, so there is no net precession.

However, there is a complication. If you apply a torque to the system, the tiny bit of precession that each rotor is able to perform will cause stress on the frame – compressive stress on one side of the frame, and tensile stress on the other side of the frame. The resulting strain in the frame will cause the frame to act like a spring, and resist the rotation you’re trying to apply to the system. If you remove the torque from the system, the frame will spring back to its original position.

In short, the answer to the original question is "no", and the answer to Carnildo’s question is "yes."

In the real world, there would of course also be other complications such as friction between the rotor and the frame, a finite yield strength of the frame, etc., that I’m ignoring in the treatment above. MrRedact 11:10, 12 November 2007 (UTC)

LEL and UEL of gases.

I looked at a table on your website which states the LEL and the UEL of various gases. How do I know that the information seen on your website is correct? Is this ever checked or is this just something that someone put together? I'm keen to use your website but only if the information has been verified and is correct. Thank you. Mr Sangster. —Preceding unsigned comment added by Andy Sangster (talk • contribs) 10:38, 9 November 2007 (UTC)

If you're referring to Explosive limit, then you should check the references at the bottom of the page. All information on Wikipedia should be properly sourced, so you can go to the sources if you want to be sure. -- JSBillings 13:13, 9 November 2007 (UTC)

To be honest - there are no guarantees. Whilst Wikipedia editors are supposed to provide references for all of the facts they list, this is far from typically the case - and even if there are references, you can't know for sure that the author of the article typed them in correctly from those references. Worse still, some annoying little kid could have come along and messed up all the numbers for a joke. That is actually very rarely the case - but if you want absolute guarantees - there aren't any. In the case of this article, they have not indicated specifically where that particular information came from - but merely listed the two references were used in writing the article. In order to check that this particular set of information is true, one would have to look into the references and check to see that the information in the article actually agrees with them. In a better referenced article (such as the ones I wrote for the Mini and Mini Moke cars), you'll see little blue tags that look like this: ^[25] which you can click on to take you to the exact reference where that particular fact came from. However, as I said, sadly not all articles are referenced to that standard. As a practical matter, most scientific Wikipedia articles such as Explosive limit are reliable. I wouldn't use the information (without checking the references first) if someones life depended on it - but for more casual uses it's convenient. Wikipedia has been shown in several surveys to be more accurate than printed encyclopedias such as the Britannica. So I guess you can trust Wikipedia to the same degree that you'd trust any general encyclopedia. SteveBaker 13:53, 9 November 2007 (UTC)

Wikipedia is inherently no more or less reliable than any other encyclopedia. Per Wikipedia's Risk disclaimer and General disclaimer, you should place the same trust in this material as you should in material from any general encyclopedia: none at all. If you are going to be handling flammable gases, contact the manufacturer for up-to-date information (UEL and LEL are often listed in the MSDS that ships with products), or perform your own tests. Depending on your location, there are any number of independent testing labs that can measure vapour pressures and explosive limits, as well. TenOfAllTrades(talk) 14:23, 9 November 2007 (UTC)

Of course Wikipedia is less reliable than a real encyclopedia. It has advantages in other areas, of course, but professional editing counts for something. --Anon, 02:00 UTC, November 9, 2007.

Surprisingly, (actually, AMAZINGLY SURPRISINGLY) that's not true. Wikipedia is actually more reliable than almost any other encyclopedia - the venerable Encyclopedia Britannica is normally considered the 'gold standard' of encyclopedias - and Wikipedia is about on a par with it in terms of accuracy and miles ahead on breadth of coverage. Wikipedia is by any measure most certainly a 'real' encyclopedia - whatever that means. As to whether "professional editing" matters - I'd say that results say not. Here are some often-quoted facts:

• A 12-year-old kid [1] found five errors in Britannica after just a couple of days of checking. His only recourse was to write to the editor, and the errors may be corrected in print in a few years.
• Nature magazine did an extensive study of science articles by experts in those fields and found: "Our staff compiled lists of factual errors, omissions and misleading statements that the reviewers pointed to (we had 42 usable responses) and tallied up the total number for each encyclopaedia: 123 for Britannica, 162 for Wikipedia." - of course all 162 of the Wikipedia errors were fixed within a few days of the list being made public. You still can't buy a copy of Britannica with the 123 errors fixed up.
• Wikipedia:Errors in the Encyclopædia Britannica that have been corrected in Wikipedia
• Wikipedia:External peer review

So don't write off Wikipedia as "obviously" less reliable - there have now been half a dozen proper academic studies - and they all sow that Wikipedia and Britannica are about equal - and both are miles ahead of any other general-purpose encyclopedias out there.

SteveBaker 18:56, 10 November 2007 (UTC)

It's safe to say Britannica and the other "professionally edited" encyclopedias don't have quite the same vandalism problem, though... —Steve Summit (talk) 20:39, 10 November 2007 (UTC)

Also, if only to play devil's advocate, those "often-quoted facts" might seem to an impartial outside observer to be a wee bit biased and one-sided. The first doesn't say anything about Wikipedia's error rate; the second says that Wikipedia has (or had) more errors than Britannica. The third and fourth come from Wikipedia itself, so despite Wikipedia's vaunted principle of NPOV, they can't be assumed to be entirely balanced.

(I bet I could find five errors in Wikipedia after only a couple of minutes of checking -- what does that say?) —Steve Summit (talk) 20:46, 10 November 2007 (UTC)

You aren't a 12 year-old. SteveBaker 23:29, 10 November 2007 (UTC)

To answer the middle part of the question: yes, the website was "just put together by someone" -- quite a few different someones, in fact -- and it has also been checked, if not 100% systematically, by other someones.

Now, for any given fact, was it entered correctly by the someone who entered it, and has it ever been checked by someone else? Maybe. Maybe even probably. But definitely not definitely. —Steve Summit (talk) 23:18, 9 November 2007 (UTC)

methylphenidate Q.

http://wiki.riteme.site/wiki/Ritalin#Known_or_suspected_risks_to_health

The R.A. El-Zein study says it will cause chromosomal abberations. I'm no biologist and dont really understand these things, but does this just refer to normal body cells and the only problem is that it could possibly cause cancer, or will it mutate gamete cells as well and these mutations passed on to offspring... thank you Rocktruly21 14:43, 9 November 2007 (UTC)

That study only tested lymphocytes for chromosomal abberations, so this would be called "need for further testing." It should be noted, however, that this study's results were not reproduced to any extent by a much larger but otherwise identical study, as mentioned in the same section you linked to. Someguy1221 18:23, 9 November 2007 (UTC)

SILVER RINGS

hi again.. please choose one of those 4 choices as an answer. question= SILVER RINGS ARE... choices= a) homogenous mixture. b) compound c) element please justify to me your answer because i have a test coming up in this and i REALLLY need to know since my book doesnt provide an answer. thank you alot, jimmy —Preceding unsigned comment added by 212.71.37.73 (talk) 20:00, 9 November 2007 (UTC)

Do you mean rings made of silver? If so, then, if they were not rings what would they be? —Tamfang 20:09, 9 November 2007 (UTC)

Jewelry is not generally made from pure elements, even though they are named to make you think they are; pure gold or silver just don't have the necessary strength. RIngs are made of alloys, which are homogenous mixtures. When you're talking about jewelry, "gold" = gold + copper or nickel or palladium; the actual gold content will be specified in terms of karats, with 24 karat being pure gold. "Silver" = silver + copper or germanium, zinc, platinum, silicon or boron.; silver content is specified in terms of percentage. (a) is the answer you're looking for. - Nunh-huh 20:26, 9 November 2007 (UTC)

Silver jewelery is most often an alloy called sterling silver. Graeme Bartlett 20:43, 9 November 2007 (UTC)

Since this is a test - I'd bet the answer is 'Element' because silver is an element. There are practical matters to do with how jewellery is often made of an alloy of silver and something else - but unless you are doing a test in jewellery-science, they won't expect you do know that. The point is that 'silver' is not like 'bronze' (which is a homogeneous mixture) or 'sugar' (which is a compound). SteveBaker 21:48, 9 November 2007 (UTC)

On the contrary, "silver" in the mouth of a jewelry dealer means "mostly silver" = silver alloy. If the answer isn't (a), demand a recount. - Nunh-huh 22:55, 9 November 2007 (UTC)

Umm, what is (d), the fourth choice? hydnjo talk 23:38, 9 November 2007 (UTC)

the scifi kitchen

If you were to cook beef in an oxygen-free atmosphere, would it turn brown? —Tamfang 20:08, 9 November 2007 (UTC)

I'm not a chemist, but the browning reaction is the Maillard reaction, in case that helps anyone. -- Coneslayer 20:17, 9 November 2007 (UTC)

Yes it would still go brown, and black if you over heated it! Think what happens when you deep fry food. There is no oxygen in the liquid hot fat, but things still go brown or black. Graeme Bartlett 20:40, 9 November 2007 (UTC)

Ever heard of "ear music" heard by hearing impaired people?

A person who worked with hearing impaired people remarked at a seminar recently that there was such a thing as what she termed "ear music," if I recall the term correctly. I haven't found it under similar terms or this, but anyway, she said that it was sounds, almost like phantom limb of the ear, that the nerve endings pick up when it's really quiet that aren't there, as if a low radio were playing in another room or something. I asked specifically if tis might be hypnagogia, and she said this was something different, it wasn't just when one was nearly asleep. Have you ever heard of it? I found it odd there was an article under phantom eye syndrome here (which i'd never heard of myself]] but not phantom ear, but she didn't call it phantom ear. (In fact, if she had, I'd have guessed from context what she meant right away.)Somebody or his brother 20:15, 9 November 2007 (UTC)

Sounds like something similar to hallucinations experienced during sensory deprivation. Information on the web on this seems scant- most seems related to various mental disorders and brain lesions, none of which relates to hearing impairment as a whole. But I'm not sure. Maybe check the references on that page, or see hallucinations in the sane. SamuelRiv 21:36, 9 November 2007 (UTC)

Like Tinnitus? SteveBaker 21:42, 9 November 2007 (UTC)

You might be interested in Oliver Sacks newest book, Musicophilia: Tales of Music and the Brain, which devotes a whole chapter to this topic. It is apparently a lot more common than once thought, especially among the hearing impaired. Sacks calls it musical or aural "hallucination", while noting that some people object to the word "hallucination". Pfly 09:02, 10 November 2007 (UTC)

(later addition) I skimmed the chapter this morning for a bit more specificity. It's chapter 6, titled "Musical Hallucinations". Some of the things Sacks says about it -- musical hallucinations were once thought rare and perhaps associated with temporal lobe epilepsy (TLE), but in recent years it has been recognized as more common and only rarely associated with TLE. Musical hallucination is not a psychosis, not "mental illness"; rather it is "real", "physiological", and benign. Sacks stresses this point -- some people have suggested a similarity between musical hallucinations, "hearing music", and schizophrenic "hearing voices", but Sacks shows how very different the two are, both physically in the brain and in the way they are experienced. Musical hallucinations can take many forms, but common aspects include: hearing music "for real", not just "in your head"; often associated with hearing loss and "emerging" from humming and buzzing type noises (eg, humming refrigerator, tinnitus, etc); more common in the elderly but can occur at any age; when caused by something like a stroke, tends to die away with recovery, otherwise musical hallucinations tend to be "very persistent" and "chronic". Some of the striking differences mentioned: for some people the music is hear very loudly, while for others it is soft and vague. For some it can be very annoying and even intrusively disruptive, while for others it can be pleasant and easily ignored. For some the music tends to be "whole pieces" or at least whole melodies, while for others the music "fragments" into tiny bits that skippingly repeat endlessly. Most people cannot control it, but some are able to "direct" it to some degree. It is not very well understood, neurologically. There is no cure. People for whom it is life-disrupting, a doctor might be able to find ways to reduce its strength. Sacks writes that of the people he knows of who have musical hallucinations, about 80% also have some kind of hearing impairment. Also, of all people with hearing impairment, about 2% develop musical hallucinations. There's lots more in the book, and as always Sacks writes very engagingly. Pfly 19:59, 10 November 2007 (UTC)

Why is chicken, rabbit and pork meat a different color from cows, deer,elk etc?

This isn't a joke, I am truly wondering why creatures with the same basic physiology have different colored meat. Respectfully, curious —Preceding unsigned comment added by 209.237.84.150 (talk) 21:00, 9 November 2007 (UTC)

It's determined by the concentration of myoglobin in the muscle cells. See white meat and red meat. --Carnildo 21:40, 9 November 2007 (UTC)

It's not just the myoglobin but also the concentrations of mitochondria. Dark meat has more mitochondira per cell, while white meat has less. David D. (Talk) 22:23, 10 November 2007 (UTC)

As a sidenote, nitrite is used to prevent the myoglobin from decaying in cured meat. Icek 04:09, 11 November 2007 (UTC)