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June 2

Why doesn't Wellbutrin and an SSRI used in combination result in similar to the triple reuptake inhibitor cocaine?

Wellbutrin is a dopamine-norepenephrine reuptake inhibitor, SSRIs inhibit the reuptake of serotonin. Cocaine inhibits the reuptake of all three.

Also, would long-term Wellbutrin /SSRI use increase or decrease the norepinephrine response to a beta-2 agonist at the norepinephrine receptor? 71.2.172.65 (talk) 03:35, 2 June 2013 (UTC)

It's not as simple as that. One has to factor in pharmacokinetics and differing affinity ratios. Hundreds of compounds have affinity for the SERT, NET and DAT but do not produce the effects of cocaine. In fact, cocaine is a nebulous term because it has vastly different effects depending on if it is taken orally, insufflated, injected or inhaled (see coca tea, crack cocaine). Markr4 (talk) 14:25, 2 June 2013 (UTC)

It's been some time since I last looked into the mechanism, and alas, I shan't get around to it soon, but it is covered to some degree in the cocaine article which mentions some other things like sodium channel. Speculation from long ago, not an answer: the drug interacts with a lot of different receptors for various neurotransmitters, some of which, AFAIR, work as dimers of protein; it is possible therefore that this drug might bring two different receptors to cross-react that don't normally have a reason to talk to each other... Wnt (talk) 18:10, 2 June 2013 (UTC)

My tea rots

I drink herbal tea (that's technically tisane, since no tea leaves are involved) without any sugar or sweeteners added, and no milk/cream either. Normally it doesn't go bad, presumably due to the lack of sugar. However, there is one variety which seems to go bad extremely fast. It goes from clear to foggy, and smells and tastes bad, in a few hours at room temperature. I would like to know why this particular herbal tea spoils rapidly, when others do not.

It's Bigelow "Mint Medley", and here are the ingredients:

Peppermint leaves
Spearmint leaves
Rose hips
Lemon peel
Hibiscus

1) Now, my first thought is that some of those ingredients might have sugar in them, such as the last 3. Can such a tiny amount of sugar make the diff ?

2) Also, the lemon peel might contribute some oil (as might the other ingredients). So, could the oils somehow go rancid in such a short time period ?

I won't buy this particular product again, but would also like to know which ingredients to avoid in the future. For comparison, I also drink an herbal tea which is just peppermint leaves. It spoils too, but takes at least twice as long. And finally, I drink another tea containing cinnamon and many other spices which never seems to spoil at all. So, peppermint seems to be at least part of the problem, but not all of it. StuRat (talk) 04:18, 2 June 2013 (UTC)

The rose hips contain sugar, and quite a bit. One ounce of dried rose hips contains about 5 or 6 grams of sugar [1]Dollars to donuts, that's the culprit. Dominus Vobisdu (talk) 04:35, 2 June 2013 (UTC)

Wow, and saturated fat and sodium, too. I guess rose hips are nature's junk food. :-) StuRat (talk) 05:22, 2 June 2013 (UTC)

Except that they've been touted for years as having a far higher Vitamin C content than just about anything else. -- Jack of Oz ^[Talk] 05:26, 2 June 2013 (UTC)

Well, rose hips are fruit, and dried fruit concentrates everything in it. 21 grams of sugar/ounce for dried rose hips compares similarly to the 17 grams/ounce for raisins and the 15 grams/ounce for dried, sulfured apricots. --Jayron32 05:27, 2 June 2013 (UTC)

That's 21 calories from sugar per ounce, not 21 grams. That's equivalent to about 5 grams. Still plenty of sugar, though. You can make rose hip preserves (like apple butter) without adding any more sugar. Quite nice. Dominus Vobisdu (talk) 05:36, 2 June 2013 (UTC)

No, your source says 21 grams of sugar. It's not explicit, but the data says: 1 oz.: carb 21, protein 3, fat 1 calories 101. 21+3+1 does not equal 101. 21+3+1 = 25, which makes sense in that 1 oz. = 28 grams, so the other 3 grams are other stuff. 21*4 + 3*4 + 1*9 = 105, which is off a bit, but my guess is there's some rounding errors we're not seeing in their data. Now, technically 21 grams of carbs is not 21 grams of sugar, some of it could be starches or dietary fiber, but even for total carbs, it is roughly the same as other dried fruits cited above. --Jayron32 05:43, 2 June 2013 (UTC)

Look again. Down on the right, it says 5.67 grams of sugar. Don't know where the 101 calories came from. Possibly a mistake. Dominus Vobisdu (talk) 05:50, 2 June 2013 (UTC)

AH. Thanks. No the 21 grams was for total carbs. Rose hips have a lot of fiber. And the 5-6 grams of sugar is actually a lot less than other dried fruits then. Based on that I'm not sure it's contributing a whole lot to the total sugar of his tea. How much of the tea is rose hip? 10%? That'd be an extra half a gram of sugar, which is equivalent to a few granules of granulated sugar. More likely that the tea is going "off" in a few hours due to other factors, such as over-oxidation, or as is usually the case, over-steeping. Stu, are you leaving the tea bags in for the whole time? Because long steep times or high steep temperatures will extract different compounds from the tea, and will change the flavor profile greatly. It's not clear hear that "bad" means "bacterial growth" or something else at work. --Jayron32 06:02, 2 June 2013 (UTC)

I tend to leave the tea bags in for the cinnamon tea, but not for the mint teas, so, according to your theory, the cinnamon tea should go off, not the mint tea. The combo of going cloudy, smelling bad and tasting bad certainly implies bacterial growth to me, but it does seem amazingly fast, I agree, for a tea with no added lipids or sugars. Hence the question. StuRat (talk) 06:21, 3 June 2013 (UTC)

Why do you make so much at a time, Stu? Why not just make it a cup at a time, as you need it? That way, it'll never get the chance to go off, assuming you keep your ingredients dry and airtight. -- Jack of Oz ^[Talk] 04:52, 2 June 2013 (UTC)

I like my tea weak. I only use one tea bag, but this makes about a quart/liter. It takes me a few hours to drink. I don't like having to constantly make more tea, so this suits me fine, as long as it doesn't go off. StuRat (talk) 05:22, 2 June 2013 (UTC)

If your talking about "a few hours", it's unlikely that bacterial growth is the problem. The turbidity is probably caused by polymerization of pectins from the rose hips and lemon peel. That shouldn't affect the taste or odor much, though. If I were you, I'd slide it under the microscope and check for the presence of bacteria. It may be that some componenent of the tea is SOOOOO saturated with bacterial endospores that a population large enough to spoil the tea within hours is possible. As for oxidation, that's not likely. The vitamin C in the rose hips and the anthocyanins in the hibiscus flowers should provide enough antioxidant power for a few hours, all the more so since the water was degassed while boiling. Dominus Vobisdu (talk) 18:00, 2 June 2013 (UTC)

Yeah, bacterial growth seems unlikely to me off the cuff. Fastest doubling time isn't going to be faster than 20 minutes, and that's for a bacillus in nutrient broth, well aerated. So 3 hours would be maybe 1000 times the original count, which wouldn't cause visible turbidity. And just herbal tea rather than something like chicken soup would be a lot slower (after all, if you leave a mug of chicken soup out for a few hours, it doesn't turn cloudy, and that's a lot more nutritious); might never even get to turbidity at all, there's really not a lot of nutrient there. And just sitting in a cup, non-aerated would be even slower still. As for the question of waking up spores en masse, I really doubt Bigelow is going to market anything with that degree of contamination. Gzuckier (talk) 02:05, 5 June 2013 (UTC)

If I may quote you: "Ahem" - that would be "If you're talking ...".  :) -- Jack of Oz ^[Talk] 21:12, 2 June 2013 (UTC)

And if I may quote Brother Savatore, "Stupido! Stupido! Penitentiagite! Dominus Vobisdu (talk) 21:16, 2 June 2013 (UTC)

Ahem. That would be Salvatore.  :) Actually, I was given that book for my birthday last year but I've not had a chance to read it yet. I will now find time. Thanks. -- Jack of Oz ^[Talk] 21:25, 2 June 2013 (UTC)

Somebody must really love you! It's a great read. Enjoy! (Hope I spelled everything write that time) Dominus Vobisdu (talk) 21:29, 2 June 2013 (UTC)

Thanks so far, everyone. It looks like I should avoid rose hips, and maybe peppermint. Are the rest of the ingredients OK, as far as everybody knows (meaning they don't cause rapid spoilage) ? StuRat (talk) 03:32, 5 June 2013 (UTC)

Not necessarily. It may be specific to this particular product. Again, I'm very skeptical that microbial spoilage is taking place. Even ground beef doesn't go off in a few hours unless it's horribly contaminated, and that's a lot more hospitable to microbes than herbal tea would be, especially with no added sugar. The increase in turbidity does not necessarily indicate microbial growth, and there are other more likely causes. Nor does the change in smell or taste, which could be due to the fact that pleasant volatiles evaporate fast and no longer mask less volatile, less pleasant components.

In short, you'll just have to experiment with different products to find one that remains palatable after a few hours at room temperature. I wouldn't necessarily exclude rosehips or peppermint at this point. Dominus Vobisdu (talk) 08:57, 5 June 2013 (UTC)

What force binds the cells in multicellular organisms together?

We know, that atoms in a molecule are bound by covalent bonds, large celestial objects are bound by gravity, particles inside an atom are bound by the strong force, and so on. However, what binds the cells in a multicellular organism together? — Preceding unsigned comment added by 5.15.15.144 (talk) 09:26, 2 June 2013 (UTC)

see Cell adhesion IBE (talk) 10:01, 2 June 2013 (UTC)

Midnight sun and bird activity

I passed through Saint Petersburg, Russia this week and they are just about ready to dive headlong into the White Nights Festival. Seeing the sun at 2300 for the first time is a source of real cognitive dissonance, and as a birdwatcher I wondered about the effect such a long daytime period has on birds? Does the dawn chorus still happen? Are they active all day? Active from 0400 to 0600 and then rest almost the entire "day" ? As I was in the city on business I hadn't time to venture out and make personal observations... The Masked Booby (talk) 11:46, 2 June 2013 (UTC)

Living in Cambridge Bay you can see active birds 24 hours a day. As to the Dawn chorus (birds), the little buggers are more than happy to keep that going all day as well. The birds include ravens, Snow Buntings, gulls and sparrows in town as well as various geese, shore birds and others listed at List of birds of Nunavut out of town. CambridgeBayWeather (talk) 00:53, 3 June 2013 (UTC)

Air Conditioning and Global Warming

This may well be the dumbest thing I've ever done, but a kid at work asked me this and I honestly couldn't provide a reason why this wouldn't work, other than 'common sense'.

If everyone with air conditioning ran their air conditioning for an arbitrary amount of time (say, 24 hours) why would the cold air being produced not affect global warming?--TKK ^{bark !} 12:55, 2 June 2013 (UTC)

Air conditioning works by transferring heat from one lot of air to another lot of air, meaning the net effect is null. Actually, the waste energy inherent in the process of air conditioning, contributes to global warming. Plasmic Physics (talk) 12:59, 2 June 2013 (UTC)

The waste energy I'm talking about, is in the thermodynamic sense. Plasmic Physics (talk) 13:01, 2 June 2013 (UTC)

Ah, okay. I've never actually had an air conditioner so they're a bit of a black box to me haha. Thank you!--TKK ^{bark !} 13:08, 2 June 2013 (UTC)

Actually most air conditioners are a pale neutral color with vents and buttons on one side, and an aluminum grating on the other, not black. Maybe this is why you have had difficulty tracking one down? μηδείς (talk) 13:45, 2 June 2013 (UTC)

Black box. It has nothing to do with its colors hahaha, it just means that i know that hot air in -> cold air out but not how its actually done. --TKK ^{bark !} 14:07, 2 June 2013 (UTC)

You don't need to understand the small details of how devices like air conditioners, refrigerators or any other kind of cooling device works in order to prove that you can't solve the problem this way. All you need is the First law of thermodynamics - which tells you (amongst other things) that energy is always conserved in a closed system. So if you take a completely unknown device and place it in an enclosed, perfectly insulated "black box", then feeding electricity into the box will increase the temperature inside - no matter how the device works. Hence, for an air conditioner or a refrigerator or a peltier device (sometimes used for cooling computer chips) - or for any other known or unknown past, present or future cooling technology, the amount of cooling it does is always going to be less than the amount of waste heat it generates by an amount precisely equal to the amount of electricity it consumes. So any effort whatever to cool the earth with refrigeration is doomed to failure.

If you want to cool the earth, you either have to reduce the amount of sunlight hitting the earth by an amount slightly larger than the amount of energy we're burning from fossil fuels (eg place a large mirror out in space between earth and sun) - or increase the amount of energy radiated out into space by a similar amount (eg by covering large areas of the planet with mirrors).

Sadly, the amount of area that either of those solutions would require is implausibly vast.

There is a second way to increase the amount of energy radiated outwards - and that is to remove CO2 from the atmosphere to make it more transparent in the infra-red wavelengths so that more heat can be radiated away into space...and guess what the experts in the field are asking us to do?

SteveBaker (talk) 13:51, 2 June 2013 (UTC)

You could think of a reverse heat pump where you cool the atmosphere and inject heat deep below the Earth's surface. If the heat pump is powered by solar, wind or nuclear power, it could work. Count Iblis (talk) 13:36, 2 June 2013 (UTC)

Not in the long term. No matter how deep you go, adding heat below the surface will gradually increase the amount of heat leaking back up into the atmosphere. SteveBaker (talk) 13:51, 2 June 2013 (UTC)

Haha! Finally I catch SteveBaker in a mistake, after months of trying! The amount of sunlight you'd need to reflect by increasing planetary albedo actually has nothing to do with the amount of energy obtained from the fossil fuels. There are highly effective greenhouse gases that don't involve energy generation at all - for example, if methane leaks from a natural gas well or the rear end of a cow. The heat generated by the fossil fuels is self-limiting because if the planet is warmer it radiates more energy. Wnt (talk) 17:53, 2 June 2013 (UTC)

Though it is true that heat pumped below the surface will eventually come back out, if we were looking that far ahead we wouldn't have global warming. :) The real problem is just that the amount of cooling produced by all these air conditioners won't matter much. A 100x100 mile square of Nevada matches the entire U.S. electricity usage [2]; in fact, the waste heat from fuels is estimated at 0.007% of the Earth's energy budget in that article. It's hard for me to extract an actual figure for how much the greenhouse warming increases the energy flow for direct comparison, but consider that CO2 is up 39%. Wnt (talk) 18:03, 2 June 2013 (UTC)

• You can't do work with heat in a closed system. The earth serves as a closed system here, given we're talking of global warming. See Maxwell's Demon. μηδείς (talk) 19:42, 3 June 2013 (UTC)

• But you can perform work to move heat from the atmosphere to heat the Earth's interior. So, if we take an amount of heat of Q from the atmosphere at temperature T1 = 15 C and we want to dumpt this underground at a few kilometers depth where the temperature is T2 = 70 C, we need to perform an amount of work W and then dump an amount of heat of Q + W at 70 C. The lower limit of W follows tfrom the requirement that the entropy doesn't decrease. The change in entropy is -Q/T1 + (Q+W)/T2 (with T1 and T2 in Kelvins), equating this to zero gives W = (T2/T1 - 1) Q = 0.19 Q. So, Q = 5.24 W. To offset the increased forcing due to our CO2 emissions we would have to use all our present day power generation capacity, so this not a practical solution. Count Iblis (talk) 20:00, 3 June 2013 (UTC)

Explosive boiling of water in a cooking pan on a stove

I have observed this happen and I think I know why it happens. I can reproduce the circumstances under which this happens as I'll describe below. But it's still a bit surprising to me that this works, previously I would have thought that you would need to use a microwave with the turntable disabled to make superheated water which will boil explosively when you stir it.

To observe explosive boiling of water, I put 5 liters of water in a big pan, turn the heat on until it boils. Then I turn off the heat for a while (about 15 minutes). Later when it is time to boil the macaroni, I put the heat on for a minute or so until the water boils again. The explosive boiling happens when I put the macaroni in the water. This will happen even if the heat is turned off after the water is boiled for the second time. With the heat off, the water doesn't boil anymore, yet it will boil explosively for 5 to 10 seconds (still with the heat off) after the macaroni is put in the pan. Depending on the amount of macaroni you put in the pan, you can have a violent enough explosion to get water and macaroni ejected from the pan, flying several meters away.

The explosive boiling does not happen when the macaroni is put in the pan when the water is boiled for the first time. When the water boils for the first time, it boils in a different way compared to when it boils the second time. The first time, you see a lot of small bubbles when it boils, while the second time you see a few big bubbles, usually just one huge bubble.

So, what do the Ref Deskers think is the explanation for this phenomena? While I do think the explosive boiling is easy to explain, the reason why the water boils differently the first time isn't very clear to me. Count Iblis (talk) 13:32, 2 June 2013 (UTC)

In the first boil dissolved gasses are driven off. Those are the small bubbles you see.--Digrpat (talk) 14:08, 2 June 2013 (UTC)

The term you want here is 'superheating' i believe. You get a similar effect if you microwave a mug of water for four or five minutes and then drop in a tea bag. --TKK ^{bark !} 14:10, 2 June 2013 (UTC)

Sound to me that you're just observing Nucleate boiling--Aspro (talk) 14:19, 2 June 2013 (UTC)

I believe Aspro is correct. The phenomenon you can acheive in the microwave is when water raises to slightly above "normal" boiling point without boiling, and then can be "set off" all at once by adding coffee granules or something. What the OP is describing is when water is just below or at boiling temperature, but the pasta gives it far more nucleation points so it boils over. Even throwing in a handfull of salt into water can cause a momentary "boiling over". I also doubt the "flying several meters away" claim. I've cooked quite a bit of macaroni in my time and have ocasionally had it leave the pan, but not flying several meters away. I'd have to see footage of this happening before I believe it. Vespine (talk) 02:31, 4 June 2013 (UTC)

Yes, the introduction of nucleation points is relevant, but I'm pretty sure that the water in the pan at some depth being at a higher pressure also plays a role here. I don't observe this very violent reaction when I have less than 4 liters of water in the pan. So, what I think is going on is that the second time the water has been boiled and the heat turned off is that the water near the bottom of the pan is at a temperature higher than the boiling point at the surface, because it's under pressure and the local boiling point is higher there. Then if I poor the macaroni in (with the fire off), it will lead to convection induced by the extra nucleation points causing boiling, but this then brings the water at some depth to the surface that is at a higher temperature than the boiling point at the surface, leading to explosive boiling there. Count Iblis (talk) 12:32, 4 June 2013 (UTC)

If the pot is has a full foot of water in it, that is only approximately ½ a psi of hydraulic pressure differential in total (a pressure cooker works at about 5 psi). Second, The pot gets heated from the bottom and has is a heat conducive surface so the resulting thermal circulation (which continues after the heat source is removed) means the water is not in stratified isothermal layers. So no, that don't compute at all. That you have observed this phenomena only over over four litres indicates that the thermal mass is insufficient below this volume. Mice lose a greater amount of heat percentage-wise than an elephant because of the ratio of skin area to mass. --Aspro (talk)

Other thoughts that could explain the magnitude of this 'explosive' reaction is: macaroni, spaghetti etc., is dry with a low conductivity and low specific heat capacity. So it won't cool the water down much but all the gas it contains will expand according to Boyle's law and add the the nucleate boiling. Perhaps a warning should be added to the cooking instructions: “When cooking more than four liters be sure to wear goggles and get your mom's/wife's permission to mess up the kitchen beforehand ”.--Aspro (talk) 21:19, 4 June 2013 (UTC)

Cats Shedding Oocyst

When cats shed oocysts, does that mean the Toxoplasma "leaves" the cats' bodies or does some Toxoplasma stay behind?173.180.7.3 (talk) 10:49, 2 June 2013 (UTC)BeeCier (Question moved from Talk:Toxoplasmosis)

Toxoplasma can also reproduce asexually (without producing oocysts) in the cat's intestine, so the cat is still infected while shedding oocysts. [3] Danger ^{High voltage!} 16:18, 2 June 2013 (UTC)

There are few things more arcane, mysterious, and underappreciated than the life cycles of parasites, but to my doubtless flawed understanding, the end of oocyst shedding is due to immune reaction rather than some sort of salmon-like die-off after spawning. See [4]. Basically, there are two main kinds of -zoites: the "brady" (slow) variety which encyst in muscle and wait to be eaten by somebody, and the "tachy" (fast) which spreads like wildfire right after infection or in people with AIDS, etc. Unlike in humans, where most of our lives are diploid, in these parasites most of their lives are spent as haploid with the diploids formed only when special differentiation into more-or-less eggs (macrogametes) and more-or-less sperm (microgametes) occur to some of the tachyzoites breeding in the intestine. [5] These are only a fraction of those available, an optional sexual step that can recombine strains if more than one is present, but according to that ref there aren't even mating types, which if true means the same tachyzoite might decide to become male, female, or just keep breeding. (I may well be missing something important about this biology here). Wnt (talk) 17:47, 2 June 2013 (UTC)

Steering of hot air balloon in horizontal plane

Is it possible to steer hot air balloon horizontally by directing the burner left or right so that balloon would sway and turn accordingly?--93.174.25.12 (talk) 16:22, 2 June 2013 (UTC)

You can certainly make a zeppelin which moves around with fans. But with the balloon, I should ask: where does the hot air go? If you're spewing it out into space, sure, you have some very very very crude form of jet propulsion. But if you're directing it up into the bag... what do you suppose happens when the jet pushes against the fabric of the far side? Wnt (talk) 17:22, 2 June 2013 (UTC)

No you can't. Our hot air balloon article describes how "Some hot air balloons have turning vents, which are side vents that, when opened, cause the balloon to rotate. Such vents are particularly useful for balloons with rectangular baskets, to facilitate aligning the wider side of the basket for landing." As Wnt says above, directing the burner risks setting fire to the envelope. PS Wnt, I think you mean airship rather than Zeppelin which was a specific German type. Alansplodge (talk) 18:30, 2 June 2013 (UTC)

Oddly, I wasn't even thinking about setting fire to the fabric on the far side when I said that (in theory, it could be something fireproof, though I can't imagine what) - what I had in mind was that the jet of gas pushes against the fabric with just as much propulsive force as can be obtained in the reaction from the fan, leaving you with no net force. Wnt (talk) 14:02, 4 June 2013 (UTC)

Hot air balloons are usually steered by rising or lowering altitude to an height at which the wind is blowing in the direction you want to go. As you can imagine, this is a difficult skill to master! SteveBaker (talk) 00:29, 3 June 2013 (UTC)

And there's no guarantee that the wind is going in the desired direction at any altitude you can reach. StuRat (talk) 06:10, 3 June 2013 (UTC)

Yes, exactly. But there is the possibility of at least some directional control - and balloon contests are often held for precision flying that require pilots to get a feel for the wind direction in various layers of the air - including understanding how wind changes direction to divert around hills and mountains. SteveBaker (talk) 14:16, 3 June 2013 (UTC)

Biology

If a cat smells petrol ,what will happen? — Preceding unsigned comment added by Titunsam (talk • contribs) 18:02, 2 June 2013 (UTC)

I don't know. What do you do when you smell petrol? --Jayron32 18:04, 2 June 2013 (UTC)

I'm not good at riddles. Plasmic Physics (talk) 22:18, 2 June 2013 (UTC)

If a human can suffocate from excessive gasoline fumes, presumably a cat could also. ←Baseball Bugs ^{What's up, Doc?} carrots→ 22:24, 2 June 2013 (UTC)

He didn't mention 'excessive' though. Or is that implicit by the detectable odiferous limit of petrol? Plasmic Physics (talk) 22:33, 2 June 2013 (UTC)

If an organism inhales petrol fumes in a quantity that is not excessive, then nothing is likely to happen. So the OP would have to clarify the question, in order to improve the chances of getting a useful answer. ←Baseball Bugs ^{What's up, Doc?} carrots→ 22:44, 2 June 2013 (UTC)

"Nothing" is a perfectly good answer for the question as it stands. Or maybe "Nothing, followed by the cat nonchalantly wandering off". -- Jack of Oz ^[Talk] 23:09, 2 June 2013 (UTC)

Cats dislike some hydrocarbons, such as naphthalene, so the cat may not wander off so nonchalantly, but rather make a hasty retreat. Ideas? Plasmic Physics (talk) 23:31, 2 June 2013 (UTC)

I had a cat many years ago who decided that climbing inside the engine compartment of a recently used car provided a lovely warm place to sleep on a cold day. My cars in those days were never in great condition (I was a poverty stricken student), so there would definitely have been hydrocarbon smells around. That cat lived to a ripe old age. HiLo48 (talk) 01:10, 3 June 2013 (UTC)

Interesting, but one incident hardly sets a baseline. What's the general trend among cats? Plasmic Physics (talk) 01:24, 3 June 2013 (UTC)

Off-topic discussion moved to Talk page -- Scray (talk) 01:05, 3 June 2013 (UTC)

Scray deleted a link to a discussion of this question and Titunsam's user contributions Special:Contributions/Titunsam showing he's a one-purpose ref desk editor with no other wp history. μηδείς (talk) 01:43, 3 June 2013 (UTC)

(copied from the talk page by request)

Well, I can tell you that the right to do research to determine how cats smell gasoline (specifically) is the private property of Richard Axel et al.; see http://www.lens.org/lens/patent/US_2002_0064817_A1 . The sensitivity to gasoline odor, but not its desirability, was shown to be heritable in a human study [6] so knowing more about it in the cat might help to identify a candidate gene. Gasoline is one of the specific odors whose detection is severely impaired in Parkinson's disease (PMID 12707068) - I don't know if this is true in a cat model system.

Biology has no respect for vanity. The things it is too embarrassing to talk about, whatever is too trivial to think about - these are exactly the things which, by design, can ultimately kill people or save their lives. Wnt (talk) 22:33, 3 June 2013 (UTC)

Photo of dead body

I have a question that refers to the photographs at the following link: Photographs of Ibragim Todashev's corpse. What are the stitches (and scars) that form the "Y"-shape across his chest? Is that what happens at the end of an autopsy (i.e., they stitch the body back up in such a manner, after opening up the chest cavity)? Or is something else going on? Does anyone know? Thanks. Joseph A. Spadaro (talk) 18:17, 2 June 2013 (UTC)

Yes. It's called a "Y-cut" and is commonly performed during autopsy. See out article on Autopsy for more information. Dominus Vobisdu (talk) 18:24, 2 June 2013 (UTC)

Ok, thanks. I thought so, but I was not quite sure. Thank you. Joseph A. Spadaro (talk) 19:50, 2 June 2013 (UTC)

Link: Ibragim Todashev -- 189.40.64.239 (talk) 21:35, 5 June 2013 (UTC)

June 3

Is stereophonic sound really needed for future virtual reality technology?

For example, when House of Wax was released in 1953, it was in stereophonic sound. So does this mean that stereophonic sound is intended to be indistinguishable from real life sounds? Like if a phone rings in a movie, and it's indistinguishable from a real phone ringing, can't mono sound be indistinguishable from real life sounds as well? Can't virtual reality use mono/monaural sound? Mattdillon87 (talk) 01:01, 3 June 2013 (UTC)

How many ears do you have? ←Baseball Bugs ^{What's up, Doc?} carrots→ 02:12, 3 June 2013 (UTC)

Well yes, I understand that it's because we have two ears, but I was watching tv once and a phone on tv rang. It sounded exactly like a real phone. I thought it was my phone. Does this mean mono sound is not capable of sounding real (i.e. phone on tv/phone in real life)? Mattdillon87 (talk) 02:19, 3 June 2013 (UTC)

It's not realism per se, it's that monophonic sound is not directional. The advantage of stereophonic sound (or its descendants Quadraphonic sound and 5.1 surround sound) is that they add directional and dimension to sound. The difference between them is not unlike the difference between normal flat movie and a 3D movie. When you hear a phone ring through a monophonic TV system, it can sound like a real phone ringing from the TV. When you hear a phone ring through a properly tuned surround sound system, it can sound like a phone ringing 4 feet to your left. To really get the true difference between stereo and mono sound, the best way is to listen to late 1960s-1970s era rock music on headphones. Get a copy the album Led Zeppelin II, especially the tracks "Whole Lotta Love" or "What Is and What Should Never Be" and listen to them on headphones first in mono AND then stereo and you'll hear what stereo sound does for adding directionality and motion to sound. The swirling guitars in "Whole Lotta Love"'s instrumental break, and the way the guitars in "What Is And What Should Never Be" seem to jump from place to place around the room really show what stereophonic sound can do for you. That's an album that is made to be appreciated on good headphones. --Jayron32 02:46, 3 June 2013 (UTC)

A simple example: The beginning of the Beatles song "Back in the USSR" is the sound of a jet plane landing. It moves from the left headphone to both and then to the right headphone. Hard to achieve that little effect with monaural. ←Baseball Bugs ^{What's up, Doc?} carrots→ 02:52, 3 June 2013 (UTC)

• Not only is it needed, it really isn't even enough. For one thing, we hear partly with our bodies (particularly low-frequencies); for another, we have some ability to tell whether sounds come from above or below as well as left or right. Even quadraphonic sound is not really the full story. Looie496 (talk) 03:12, 3 June 2013 (UTC)

As most people only have two working ears, one can indeed simulate any directionality with only two loudspeakers. See Gardner, William G. "Transaural 3-D Audio", MIT Media Laboratory Perceptual Computing Section Technical Report No. 342 (July 20, 1995) for an example. --Atethnekos (Discussion, Contributions) 04:03, 3 June 2013 (UTC)

It may be possible, it certainly can't be done yet in general for all listeners for all soundfields. See the problems with HRTFs in the literature, specifically with sounds close to the symmetry plane of the head level with the eyes and up.

So far as the OP goes, stereo sound adds greatly to the perception of immersion for a relatively small cost in bandwidth and processing power, compared with visual information, therefore it makes sense to use it. Greglocock (talk) 23:46, 3 June 2013 (UTC)

Did that study permit the listeners to turn their heads? Wnt (talk) 16:41, 5 June 2013 (UTC)

A few comments:

1) I find it much more difficult to pinpoint the direction of high frequency sounds than low. (This is particularly annoying when a fire alarm battery is low, and it gives off a high pitched beep, making it quite difficult to figure out which one it is.) If the phone sound was high frequency, this might explain why it's direction wasn't clear to you.

2) To really fool you, the sounds should still sound like they are coming from the desired direction if you move your head. Headphones don't really work for this, since, when you turn your head 90 degrees, it sounds like the sources of the sound also moved 90 degrees. Perhaps we could develop the technology soon to adjust for this. A stereo system with fixed speakers is a bit better, but still only fools you when you're in the "sweet spot" between the two. StuRat (talk) 06:05, 3 June 2013 (UTC)

It's not really an issue of high versus low. You can't localize very low frequencies either -- that's why a woofer can be placed anywhere in a room. What matters is relation of the wavelength of the sound to the distance between your ears. The optimal frequency is around 1000 Hz, which gives about one half-cycle of phase difference between the two ears when the sound comes from one side. Looie496 (talk) 13:54, 3 June 2013 (UTC)

What matters more is the spectrum. You can easily discern the direction of a broad spectrum noise (like a twig snapping). A square wave also has a fairly broad spectrum. Pure sinewave tones aren't as easy to pinpoint even if they have a short wavelength. This is a known problem with sirens on emergency vehicles. I remember reading a news article some years back about proposals to build ambulance sirens that produce a richer spectral tone to aid human directional detection, but the idea fell on deaf ears, so to speak, due to cultural expectations on what a siren sounds like. ~Amatulić (talk) 00:09, 4 June 2013 (UTC)

Sun's curve

Im in the UK, but the Sun appears to travel in a curve. At sunrise it is visible from the north of my home. At noon/midday it is visible only on south. Then at sunset it again appears in the north. What causes this? Pass a Method talk 11:05, 3 June 2013 (UTC)

It's the summer, and the UK is in a high northern latitude. You'll find that in the morning, the Sun is in the north-east, and in the evening, it's in the north-west. This is because (at this time of year) the North Pole is tilted towards the Sun, making the Sun appear higher in the sky overall for people in the Northern Hemisphere. Imagine heading north on a day close to midsummer: somewhere beyond the Arctic Circle, you'd come to a place where the sun didn't set at all, and could be seen due north at midnight. We're not that far north, but as we get closer to 21 June, you'll see the Sun for longer and longer periods, rising further and further in the north. AlexTiefling (talk) 11:26, 3 June 2013 (UTC)

I caught myself wondering the same thing several weeks ago, but the answer is actually quite obvious once you think about it. You can basically imagine the scenario as somewhat akin to looking south toward a place where the sun is directly overhead and moves in a straight line from sunrise to sunset. As you get further and further from this point, the trajectory of the sun will appear to bow with respect to the horizon. The sun simply can't travel in a straight line from every vantage point. Evanh2008 ^{(talk|contribs)} 11:38, 3 June 2013 (UTC)

I still dont get it. At sunset and sunrise the sun shines into my house from a northern angle. At midday it shines from a sourthern angle. What the fuck? Pass a Method talk 11:43, 3 June 2013 (UTC)

Which part of my explanation was unclear? AlexTiefling (talk) 11:45, 3 June 2013 (UTC)

(edit conflict) I'm not sure how else to describe it. You're assuming (or have assumed until now, at least) that the sun moves directly overhead in a straight line that is perfectly parallel to the east and west marks on a compass rose. That's a faulty premise. In truth, the sun moves along a line (curved to a degree determined by your latitude) that is almost always slightly off from the parallel. At the mid-point of the curve the light enters your sun from the south, while both "ends" of the line fall to the north. Evanh2008 ^{(talk|contribs)} 11:47, 3 June 2013 (UTC)

Are you talking about analemma? --TammyMoet (talk) 11:56, 3 June 2013 (UTC)

Position of the Sun explains it, but is mainly math. Sun path is in simpler terms, but is focused on solar panels, and my quick skim of it makes it seem like it describes the path, but not why it follows the path. 209.131.76.183 (talk) 12:56, 3 June 2013 (UTC)

• Draw a picture of the Earth, as a circle. Draw the equator, as a line crossing the center of the circle at an angle of 23 degrees. Draw the Sun, as a dot far away from the circle horizontally in the direction above the equator -- that's where it is an midsummer. Draw your location on the Earth at sunrise and midday. If you look at the picture this gives you, I think you'll see why the Sun is to the north at sunrise. Looie496 (talk) 13:45, 3 June 2013 (UTC)

Google Earth has a function that shows the sun and the illuminated part of the globe relative to the time of the day/year. I've found that for these kinds of questions, visualizing can often be more helpful than any written explanation. I think a way to put it however, is that in summer at sunset/sunrise, the sun shines directly on a spot that is more than 90 degrees east/west from the observer. In effect, one sees the sun as it were shining from over the Earth, thus creating the illusion that the sun is north of us. - Lindert (talk) 14:08, 3 June 2013 (UTC)

In the UK, the sun will always be exactly south at 12 noon Greenwich mean time or 1 pm British Summer Time. It will never be directly north. Alansplodge (talk) 16:42, 3 June 2013 (UTC)

Not entirely true, because the length of solar days varies with the time of year, but indeed the sun will never appear exactly north for those living between the Tropic of Cancer and the Arctic Circle. However, in summer it will appear closer to north than to south at sunset/rise, which is what the OP meant with 'in the north'. - Lindert (talk) 16:52, 3 June 2013 (UTC)

But we're talking a few seconds of difference. Also there will be a time difference if the OP lives well to the west of the Greenwich Meridian. Each major port in the UK used to calculate its own time based on the sun's zenith (noon is when the sun is at its highest point), but it caused all kinds of problems when people started travelling by train, hence the introduction of GMT. Alansplodge (talk) 17:02, 3 June 2013 (UTC)

". . . few seconds of difference." Actually up to about 16 minutes; see Equation of Time. {The poster formerly known as 87.81.230.195} 212.95.237.92 (talk) 17:16, 3 June 2013 (UTC)

I stand corrected. That's the last time I set my watch with a sundial ;-) Alansplodge (talk) 20:38, 3 June 2013 (UTC)

You were correct in saying that the sun will never rise or set in the north in the UK, though it gets fairly close to north in the Shetlands. As you also mentioned, until the days of railway travel, each town and village used to set its clock by the sun, and this was less confusing in some ways because earliest sunrise and latest sunset then occurred on the same date (the solstice). Dbfirs 22:01, 3 June 2013 (UTC)

Just to clarify, Alan. Greenwich Mean Time (GMT) was established in 1675, when the Royal Observatory was built, as an aid to English mariners to determine longitude at sea. It provided a standard maritime reference time, at a time when each city in England kept a different local time. The use of GMT as the standard terrestrial time zone for Great Britain – and this is what you're talking about @ "the introduction of GMT" – stems from 1880 (officially, but it had been gaining traction in practice for some time prior to that).

Remember, the very idea of having the world divided into standard time zones was new at that time. In 1884, the International Meridian Conference adopted a universal day of 24 hours beginning at Greenwich midnight, but specified that it "shall not interfere with the use of local or standard time where desirable". Most countries still operated under local time from town to town. And even where a country adopted one or more standard time zones, they were not necessarily related to GMT by an offset of a neat number of hours or half-hours. The system was not really generally entrenched until 1929, and Nepal didn't become GMT-compliant until 1986! -- Jack of Oz ^[Talk] 21:55, 3 June 2013 (UTC)

You are at a point on the surface of the sperical(ish) earth, this point is moving in a curved line. The sun is, for the purpose of this exercise, 'still'. You are the one moving in a curve but your local reference points are also moving in the same curve which makes it appear that the sun is moving - and in a curved pathway. (and I would check those compass bearings if I were you) Richard Avery (talk) 07:08, 4 June 2013 (UTC)

I thnk i get it now. In my mind I pictured a mini equator over the UK - on a sphere, it would curve upwards when looking to the east. Simple language for simple people :) Pass a Method talk 08:29, 4 June 2013 (UTC)

Particle decelerator, is it possible?

There is such thing as particle accelerator that converts electricity into electron kinetic energy, but is there the other part, which is a thing that can convert electron kinetic energy into electricity? — Preceding unsigned comment added by 118.136.5.235 (talk) 11:19, 3 June 2013 (UTC)

Yes, it is possible to create a device that works in reverse to a particle accelerator. Plasmic Physics (talk) 11:22, 3 June 2013 (UTC)

Well I have do a small amount of googling about particle decelerator, but nothing good has come up 118.136.5.235 (talk) 11:30, 3 June 2013 (UTC)

That would be because a device under that name does not exist. Plasmic Physics (talk) 12:07, 3 June 2013 (UTC)

So what is the proper term for particle decelerator? http://uncyclopedia.wikia.com/wiki/UnNews:Particle_Decelerator_test_run_proves_successful 118.136.5.235 (talk) 12:22, 3 June 2013 (UTC)

Slowing particles is called Particle beam cooling. There's not much call for generating power this way as there's no cheap source of energetic particles though I suppose one could call a nuclear power station a very simple version of it. Dmcq (talk) 13:14, 3 June 2013 (UTC)

Energetic electrons are also termed "beta radiation". You can block (ie bring to zero speed...or "decelerate") beta radiation with just a few millimeters of metal - although you might need more for very high speed electrons. So a good "electron decelerator" consists of a half inch thick slab of lead.

The energy produced would heat up the metal and gradually give it a negative charge. So if you had a ready source of high speed electrons, a slab of metal and a means to convert heat to generate power isn't hard. The small amount of negative charge produced could be used to produce electricity just by hooking up a wire.

But as Dmcq says - without a source of such particles, there isn't going to be much call for it. SteveBaker (talk) 14:01, 3 June 2013 (UTC)

If you decelerate energetic electrons in that way - by stopping them with a slab of impenetrable metal or ceramic - you get bremsstrahlung radiation, in addition to any residual charge collected on your device. It's not a very efficient or safe way to convert kinetic energy to useful electrical energy. Nimur (talk) 15:13, 3 June 2013 (UTC)

However, it IS an efficient way of converting kinetic energy to X-ray radiation -- which is why most X-ray machines use precisely this method. 24.23.196.85 (talk) 00:51, 4 June 2013 (UTC)

...And why on Earth would you want to generate electricity using charged particles, other than a proof of concept? Plasmic Physics (talk) 14:33, 3 June 2013 (UTC)

Well, not all electricity is generated as a source of motive power. You might (for example) measure the electricity produced as a means to determine how fast the particle stream is moving - or what direction it's coming from. Yes, of course there are better ways to do that - but there are certainly multiple reasons why one might want to create electricity from a particle beam that are not related to power production. SteveBaker (talk) 18:50, 3 June 2013 (UTC)

I meant generating electricity for the sake of generating electricity. If that is not what the OP meant, then of course, you're right. Plasmic Physics (talk) 02:51, 4 June 2013 (UTC)

Well if you ask me why do I want electricity from particles, it because I want to recover energy from free electron laser electron output. They said it can make the laser more efficient instead of just slamming it into beam dump 118.136.5.235 (talk) 08:20, 4 June 2013 (UTC)

Why not just collect the electrons directly by completing the circuit? See Crookes tube. Plasmic Physics (talk) 14:03, 4 June 2013 (UTC)

See also Energy recovery linac. Ruslik_Zero 19:23, 4 June 2013 (UTC)

Let me refer to Direct conversion and Aneutronic fusion. 81.11.190.37 (talk) 05:24, 6 June 2013 (UTC)

Well if we use it to decelerate electron we surely just need to change the anode voltage to negative right?118.136.5.235 (talk) 07:14, 7 June 2013 (UTC)

NICU

I am researching the number of neonatal intensive care units (NICU) around the world and would appreciate any leads. Melisse May (talk) 14:54, 3 June 2013 (UTC)Melisse_May

The World Health Organization freely publishes a large repository of data and statistics. You might find some of their data and estimates useful. Nimur (talk) 16:04, 3 June 2013 (UTC)

Personality trait

Is there a name for people (children especially) who need to know exactly what is going to happen next and get anxious when they can't find out? It came up in conversation - I'm not seeking medical advice. Alansplodge (talk) 16:53, 3 June 2013 (UTC)

I think there might not be a better name than "insecurity". Looie496 (talk) 17:06, 3 June 2013 (UTC)

The DSM is the authoritative reference for standard terminology regarding personality disorders. The new edition, DSM 5, was just published last week, providing updated diagnostic terminology since the previous revision (DSM IV) in 2000. Perhaps a psychology expert can comment whether there has been any change in this area. Nimur (talk) 17:29, 3 June 2013 (UTC)

How about "practical" - less likely to be taken in by salesmen and other con artists, because they would grow impatient with the "spiel". ←Baseball Bugs ^{What's up, Doc?} carrots→ 20:03, 3 June 2013 (UTC)

Nonsense. Wikipedia defines "practical" (in this sense) as "Of a person, having skills or knowledge that are practical" - which by the other definition of "practical" means "Being likely to be effective and applicable to a real situation; able to be put to use."...or..."Based on practice or action rather than theory or hypothesis" - neither of which has remotely anything to do with people who are overly concerned with what's going to happen next. Please, at least try to reference some actual information before posting this kind of nonsense! Just guessing isn't acceptable here. SteveBaker (talk) 20:52, 3 June 2013 (UTC)

I resent being called "nonsense". But feel free to try to answer the OP's question, rather than attacking other users. ←Baseball Bugs ^{What's up, Doc?} carrots→ 22:51, 3 June 2013 (UTC)

Inability to cope with changes to routine tends to be a feature of autistic spectrum disorders. --TammyMoet (talk) 20:15, 3 June 2013 (UTC)

Is that what the OP is describing? It doesn't sound like the same thing. ←Baseball Bugs ^{What's up, Doc?} carrots→ 20:24, 3 June 2013 (UTC)

I know it can be an autistic spectrum trait - I wondered if it had a "label" when it occurred in isolation, which seems to me to be fairly common. Alansplodge (talk) 20:31, 3 June 2013 (UTC)

This thread comes dangerously close to offering a diagnosis. There isn't any term for the precise symptom you're asking about - but describing someone with this system as "autistic" or anything else is to propose a diagnosis based on a symptom - and we're not allowed to do that here. SteveBaker (talk) 20:52, 3 June 2013 (UTC)

If it's common, maybe the right term is "normal". ←Baseball Bugs ^{What's up, Doc?} carrots→ 20:38, 3 June 2013 (UTC)

Another nonsense answer. It's "common" to catch a cold - but it's not "normal". Besides, what evidence are you presenting that this desire to continually know what's about to happen is in any way common? If you don't actually know the answer - just find another question. Thanks. SteveBaker (talk) 20:52, 3 June 2013 (UTC)

I assume you're addressing Alansplodge, since it was he who labeled it "fairly common". And I dispute the notion that catching a cold is somehow not normal - it happens to a large percentage of the public. I do agree that we run the risk of meandering into the diagnosis area. ←Baseball Bugs ^{What's up, Doc?} carrots→ 22:49, 3 June 2013 (UTC)

How about Risk aversion? or Ambiguity aversion--Digrpat (talk) 20:36, 3 June 2013 (UTC)

In vox populi, you call that a control freak. Titoxd^{(?!? - cool stuff)} 07:18, 4 June 2013 (UTC)

Thank you all. The top answer (in my humble opinion) was "uncertainty aversion" linked by Digrpat above. Alansplodge (talk) 12:27, 4 June 2013 (UTC)

Resolved

Why don't chocolate coated nuts have a flat spot?

I'm sitting here contemplating the perfection of a dark-chocolate coated almond, with a perfectly smooth compound curve at every point on the chocolate's surface, un-marred by any flat spot that would have formed by the almond resting on a surface as the chocolate coating cooled and hardened.

How was this feat accomplished?

Mind you, I wrote the enrober article. It was a subject that interested me at the time. But in my research for that article, all examples of chocolate enrobers involved the coated item resting on a flat surface while the chocolate hardens. This is true of all candy bars and other chocolate coated confections. They all have a flat side.

Except these almonds.

I also have a bag of chocolate coated cashews from the same store. Rather than having an ellipsoid almond shape, these nuts are more crescent-shaped with a saddle point of two opposing curvatures. At the saddle point I see a little crease in the chocolate, which could be a clue, almost as if the nut was resting on a blade as the chocolate cooled. More likely, I think, is that this crease formed naturally as a stress fracture in the chocolate surface as it shrank at the saddle point.

I hope someone can shed some light. ~Amatulić (talk) 23:59, 3 June 2013 (UTC)

It is rather simple to roll them and polish off the edges video. μηδείς (talk) 00:27, 4 June 2013 (UTC)

See Sugar panning. DMacks (talk) 03:19, 4 June 2013 (UTC)

June 4

Gravitational time dilation

Can anyone tell me a bit more aboutGravitational time dilation. Particularly how time speeds up on an aircraft. Clover345 (talk) 00:00, 4 June 2013 (UTC)

Time doesn't speed up on a moving aircraft, it slows down -- only by a minuscule amount, but enough to be measurable by a super-accurate atomic clock. 24.23.196.85 (talk) 00:45, 4 June 2013 (UTC)

Gravitational time dilation has the opposite effect. An object farther from the surface of the earth will have less gravitational time dilation, and thus at the same velocity, a plane flying at a higher altitude will have a slightly faster clock than one flying at a lower altitude at the same velocity. --Jayron32 04:37, 4 June 2013 (UTC)

Some decades ago, some source (probably the Guinness book) discussed the fact that the Apollo astronauts' clocks during their journeys to the moon had gone slightly faster than earth-bound clocks, by some number of microseconds. The book remarked that despite that fact, "No formal overtime claim was filed." ←Baseball Bugs ^{What's up, Doc?} carrots→ 13:13, 4 June 2013 (UTC)

Also interesting is that at full Moon the clocks on Earth slow down by a measurable amount. This can be detected by measuring the arrival times of pulses of pulsars. When astronomers started to use pulsars as accurate clocks, they forgot to correct for the fact that the distance of pur cocks from the Sun have monthly periodic oscillation, due to the Earth's center of mass orbiting the center of mass of the Earth-Moon System. At Full Moon we are a bit closer to the Sun than at New Moon, thefore due to gravitational time dilation caused by the Sun's gravitational field, our clocks run a bit slower during full Moon, therefore the pulses of pulsars will speed up relative to our clocks. All other effects where corrected for except this effect, so the data showed a mysterious monthly period in the delays of pulses all the observed pulsars. Count Iblis (talk) 13:28, 4 June 2013 (UTC)

I assume "all other effects" includes things like the variable sun-earth and earth-moon distances caused by the elliptical nature of the orbits in question, which will also cause variations in gravitational time dilation. --Jayron32 13:30, 4 June 2013 (UTC)

Yes, all the effects, the most important one is variable Doppler effect due the Earth's motion around the Sun (the Earth-Pulsar distance will have a periodic oscillation on top of the steady change), the next important effect is due the electromagnetic waves not traveling in a straight line but it is deflected in the gravitaional field on the Sun and the planets, then you have the time dilation effect due the the varying speed of the Earth relative to the pulsar, but this included in the relativistic Doppler effect. The gravitational time delay effects due to the elliptic orbit of the Earth, also that clocks located at different places on Earth will have relative delays w.r.t. each other. Everything has to be corrected for and if you miss one effect, you can see that. Count Iblis (talk) 13:42, 4 June 2013 (UTC)

I have no doubt the effect Count Iblis describes does actually exist. I am skeptical that any clock - experimental or otherwise, hand-held clock or physics-laboratory full of ultra-precise time-keeping equipment - has ever measured this specific time-dilation effect on perceived pulsar rates, because its magnitude must be very small. If you know of some published work, I would be happy to read about it!

For what it is worth, the LIGO - two very large and specialized facilities - are the most precise astrophysical time-keeping observatories that I am aware of. They are looking for general-relativistic time dilations due to propagation of gravitational disturbance - "gravitational waves" - and to date there have been no remarkable discoveries or observations of such dilation. I would suspect that if Count Iblis' description of gravtiational-potential time dilation is a measurable phenomenon, then LIGO should either measure it or compensate to remove it, because the magnitude of the signal they seek is even smaller. Nimur (talk) 16:00, 4 June 2013 (UTC)

The gravitational time dilation factor is (approximately) 1 − M/r, where M is the Sun's mass in this case. The variation in that due to oscillation of Earth's center relative to the Earth-Moon barycenter is ±Mr/R² where r is the distance to the barycenter and R is the average distance to the Sun. That's about ±3×10⁻¹³. The period of PSR B1913+16 is given to 13 decimal places in the article, with no explicit error margin. So they might have noticed this effect, just barely.

LIGO is an interferometer and won't notice this effect since it won't cause a fringe shift. If they ever detect gravitational waves they might, in principle, notice the frequency variation due to this effect, but only if the true frequency varies by less than one part in 10¹² over the course of a month and they can measure it to a similar precision. So probably not. Pulsars don't emit detectable gravitational radiation. -- BenRG 21:17, 4 June 2013 (UTC)

I'd be careful about assuming that LIGO will or won't notice something simply because it is an interferometer. Based on a talk I attended, LIGO notices continental drift, the solid Earth tides created by the moon, and for a while they noticed tumbleweeds hitting the outside of their facility (until more distant catch fences were erected). When you are designed to measure ridiculously tiny effects, the list of not-quite-so-tiny systematics can grow very large indeed. You are right though to the extent that LIGO wouldn't have mistaken any of those effects for gravitational waves since they each have very different physical and temporal signatures. Dragons flight (talk) 09:42, 6 June 2013 (UTC)

Second reflection in mirror

I noticed that my bathroom mirror gives a second, "ghostly" reflection slightly offset from the main one, looking like a faint, barely noticeable image of the object, obvious only for shiny reflective surfaces. How does it form? - Sikon (talk) 03:53, 4 June 2013 (UTC)

A typical mirror is a reflective surface covered with glass. (The purpose of the glass is to keep the reflective surface from being damaged, tarnished, etc., and to allow for easy cleaning.) However, the surface of glass is slightly reflective itself, especially when viewed from a shallow angle, as opposed to straight on. You've probably seen your reflection in a glass window before, so know this to be true. I suspect that this is the ghost reflection you see, with the offset being due to the thickness of the glass. StuRat (talk) 04:22, 4 June 2013 (UTC)

(edit conflict) From the front surface of the glass. Glass mirrors will reflect from the back "silvered" surface mostly, but there will always be a faint reflection from the front of the glass as well. A back-silvered mirror has the advantage of protecting the reflective surface from oxidation, but the disadvantage of the problems you note, of the double image. See This article describing the difference between "front" and "back" silvered mirrors, also called "first surface mirrors, and second surface mirrors. --Jayron32 04:28, 4 June 2013 (UTC)

The partial reflection of glass etc is an extremely facinating subject see the book (QED: The Strange Theory of Light and Matter) for a good introductory discusion! OneMadScientist (talk) 10:20, 4 June 2013 (UTC)

But is the reflected light polarized? Nimur (talk) 15:41, 4 June 2013 (UTC)

Ah... Feynman, what a champion. OneMadScientist (talk) 09:15, 5 June 2013 (UTC)

There are (in principle) even more reflections than that - a reflection from the back of the mirror can be partially reflected again by the front of the glass, then again off the back surface and finally out to your eyes. You don't notice them because the fraction of the energy of the light that is reflected at each turn becomes less and less - but if you have a really bright light source (like a laser pointer) and a dark room, and play around with the angle of the laser and the mirror, you can see more than two reflections. (Be careful not to stare directly into the laser when you do this though!) SteveBaker (talk) 15:56, 4 June 2013 (UTC)

You will certainly notice multipath reflections off undesired, non-ideal optical surfaces if you ever try to build a high-quality camera! Many types of lens flare are caused by multipath reflections off the wrong surface of an optical element - a lens, a mirror, the film or sensor... the edges of the camera case... Nimur (talk) 16:25, 4 June 2013 (UTC)

Scientific instruments, cameras and optical instruments often use a First surface mirror to avoid the extra reflection. The downsides to using them is that they cost more and the reflective coating can get scratched. Edison (talk) 20:31, 5 June 2013 (UTC)

Malignant lump

so a friend of mine had a lump tested and it was a "malignant lump" could it be anything other than cancer?--Irrational number (talk) 10:55, 5 June 2013 (UTC)

Medical advice! Plasmic Physics (talk) 11:25, 5 June 2013 (UTC)

I'm not asking for advice, I'm not asking what should I do. I'm just asking what could it be. The doctors haven't said anything more yet. I'm just asking whether it could be anything else. In other words I'm asking what are the types of malignant lumps I don't know how that's asking for advice.--Irrational number (talk) 11:21, 5 June 2013 (UTC)

<deleted medical advice> SteveBaker (talk) 15:14, 5 June 2013 (UTC)

No, this is still medical advice. We're not allowed to diagnose, offer treatment advice or give a prognosis. You're asking for a diagnosis ("what could it be?") and we're explicitly not allowed to do that. SteveBaker (talk) 15:14, 5 June 2013 (UTC)

Apart from everything else, there is so little information there, heard thirdhand, that we couldn't do any better than the search bar at answering you. Wnt (talk) 16:39, 5 June 2013 (UTC)

• The OP's asking whether the term "malignant lump" can refer to anything besides cancer. Calling that medical advice is just plain hilarious. I don't have the answer, but you can look under malignancy and malignant tumor which seem to imply the term is pretty much restricted to cancers. μηδείς (talk) 16:40, 5 June 2013 (UTC)

Let's call a spade a spade. A malignant tumor is another name for cancer. This is not a medical advice or diagnose. We are not saying anybody has cancer (no diagnose) and we are not telling anybody that does have cancer what to do with their lives (no advice). This is a matter of semantics. What is the meaning of the term malignant tumor. Answering that question is within bonds. The medical-advice-police needs to get a grip. Dauto (talk) 17:05, 5 June 2013 (UTC)

The problem is not the strict application of the rules--they don't apply here. The problem is the inability to make the logical distinction between us offering a diagnosis and us commenting whether a term has any other meaning. μηδείς (talk) 18:03, 5 June 2013 (UTC)

Fat chance of that happening. Right now they're pushing at Wikipedia:Reference_desk/Refdesk_reform_RFC for a more strict policy against anything "remotely related". Heck, I just tried to add links to two indexes of clinical trials for Tourette Syndrome only to get policies brandished at me. [7] What we need to understand is that, the right to treat, to talk about, to know about disease is the sole property of the cartel, and so we are all utterly unethical and evil for daring to think about such things. Wnt (talk) 17:54, 5 June 2013 (UTC)

Can we offer veterinary advice? HiLo48 (talk) 05:33, 6 June 2013 (UTC)

Ears, temperature, and balance

Why is it that when there is a pronounced temperature difference between your middle ears, that you experience nausea and imbalance? Plasmic Physics (talk) 11:15, 5 June 2013 (UTC)

The fluid in your inner ear ("endolymph") flows around the Semicircular canal and stimulates small hairs there that convey your sense of motion and balance. Temperature variations alter the volume, viscosity and electrical conductivity of that fluid which can result in balance issues - and nausea from motion sickness. It's easy to imagine how getting different balance information from one ear versus the other might worsen this effect. Sadly I don't have reference for the fluid viscosity/conductivity thing - it's what my doctor told me the last time I had this problem. SteveBaker (talk) 15:11, 5 June 2013 (UTC)

Thanks. Plasmic Physics (talk) 23:50, 5 June 2013 (UTC)

Our article on the caloric reflex test explains the basic mechanism. Looie496 (talk) 05:28, 6 June 2013 (UTC)

Very interesting. Auditory irrigation with warm water is part of my personal hygiene routine, but in a recent instance, circumstances required me to use cold water on one side, immediately following the use of hot water on the other side. Plasmic Physics (talk) 09:21, 6 June 2013 (UTC)

Dot markings on Torx screws

I've just bought a new Seagate hard disk drive. The top plate of this is secured by six Torx T8 screw fasteners (the normal kind, not the tamper-resistant ones). I've noticed that four of the screws are marked with four dots, and two with only a single dot. I'm confident that these are simply markings - at less that 1mm in diameter, they're too small and too shallow to have a mechanical purpose. Presumably they denote different characteristics of the two screws. I've been unable to find any information about these markings online. One can speculate that they denote different screw lengths (that's my guess), screw diameters or pitches, or the required torque (but I'd expect that to be marked on the receptacle instead). Here is a photo of the two. Is this a standard marking, where is it documented, and what to the dots denote? I don't intend to dismantle the drive to find out. -- Finlay McWalterჷTalk 12:02, 5 June 2013 (UTC)

Add 'different coating' (galvanization, phosphate coating, zinc) to your speculation. OsmanRF34 (talk) 14:33, 5 June 2013 (UTC)

I've never seen this before either - but yet another possibility is that it's some kind of quality control thing. If they have (let's say) four different machines in some factory, all turning out Torx fasteners, then they get a batch of bad bolts coming back from customers, a pattern of one, two, three or for dots would allow them to identify which machine needs attention.

I did find some comments on (of all places!) a Jeep Wrangler forum that their (very large) Torx bolts have lines marked on them. One person commented: "3 lines is a grade 5 bolt, 5 is a grade 8. no line are cheap junk" - so it's possible that this is some kind of standard quality indicator, and that smaller bolts use dots instead of lines for reasons of space. SteveBaker (talk) 15:00, 5 June 2013 (UTC)

[| 3 lines, grade 5, or 5 lines, grade 8 source] OsmanRF34 (talk) 15:22, 5 June 2013 (UTC)

I should say that the apparent difference in colour between the two is entirely an artefact of my photography (I don't really have the equipment for a decent macro photo); in actuality the finish between the two types appears indistinguishable. -- Finlay McWalterჷTalk 15:24, 5 June 2013 (UTC)

I found a fastener identification guide from a reliable source here [8]. That pdf won't answer your question, because it doesn't cover torx. The point is, they are describing different marking systems for each manufacturer! There are 'tons' of different markings, with very little standardization. The only dots I see are from the Decker manufacturing corp., but I don't think they make torx fasteners... So, I think you'll have to track down who made the fasteners to get a definitive answer. SemanticMantis (talk) 16:53, 5 June 2013 (UTC)

Interesting to note that the first photograph on the Torx page has a torx screw with three dots equidistant around the head of the screw, and it is on a hard disk drive too. 220 of ^Borg 10:44, 6 June 2013 (UTC)

Sahara

Prior to the desertification of the Sahara what was the largest desert? Don't go too far back in time and disregard frozen lands like Antarctica or Greenland. --KAVEBEAR (talk) 07:07, 4 June 2013 (UTC)

You're bumping into a definitional problem here. Our article Desert uses the definition "Deserts generally receive less than 250 millimetres (10 in) of rain (precipitation) each year." That's a kind of standard in international climate science. Naturally it includes cold places. If you have something different you'd like identified, maybe hot places with sandhills, that's a different question. HiLo48 (talk) 07:22, 4 June 2013 (UTC)

That seems to be the question he's asking, then. -- Jack of Oz ^[Talk] 08:41, 4 June 2013 (UTC)

Shouldn't it be "less than 250 millimeters precipitation (rain or snow)?" Or is it meant to exclude snowing? OsmanRF34 (talk) 12:34, 5 June 2013 (UTC)

Is she asking us to don't 1) Disregard frozen lands like Antarctica or Greenland or 2) don't disregard frozen lands like Antarctica or Greenland. Bit ambiguous if you read it. ☯ Bonkers The Clown \(^_^)/ Nonsensical Babble ☯ 08:50, 4 June 2013 (UTC)

Ah, I see what you mean. Yes, it is ambiguous. Maybe this table from our Desert article would be a good starting point...

The ten largest deserts

Rank	Desert	Area (km²)	Area (mi²)
1	Antarctic Desert (Antarctica)	14,200,000	5,500,000
2	Arctic Desert (Arctic)	13,900,000	5,400,000
3	Sahara Desert (Africa)	9,100,000	3,500,000
4	Arabian Desert (Middle East)	2,600,000	1,000,000
5	Gobi Desert (Asia)	1,300,000	500,000
6	Patagonian Desert (South America)	670,000	260,000
7	Great Victoria Desert (Australia)	647,000	250,000
8	Kalahari Desert (Africa)	570,000	220,000
9	Great Basin Desert (North America)	490,000	190,000
10	Thar Desert (India, Pakistan)	450,000	175,000

HiLo48 (talk) 08:54, 4 June 2013 (UTC)

The Sahara as a desert has only existed since 1,600 BC, our article claims (with a "citation needed", if anyone comes across a good reference). The article also says the area cycles between wet and dry periods. So there will be not one but many periods in the past when the Sahara is not a desert, as well as many periods when it was.

A climate map for around the Sahara's last wet period would show vegetation somewhere around 5000-8000 BC. So far the closest I've found is this map [9] from the last glacial maximum, which shows the largest non-polar deserts in Argentina and Central Asia-Tibet-China. 184.147.118.213 (talk) 11:23, 4 June 2013 (UTC)

That map seems to show north Africa and the Arabian peninsula, central Australia, and other areas, covered by "Tropical extreme desert" Astronaut (talk) 13:30, 4 June 2013 (UTC)

Shouldn't this question be in the Science desk? My $0.02.... Kingsfold (Quack quack!) 20:02, 4 June 2013 (UTC)

"Sahara Forest? Don't you mean the Sahara Desert?" "Yes, now!"[10] ←Baseball Bugs ^{What's up, Doc?} carrots→ 22:09, 4 June 2013 (UTC)

The Sahara pump theory article has some information related to that question. Dauto (talk) 14:34, 5 June 2013 (UTC)

It would be nice to get more information on deserts in recent geological eras. I remember reading Florida was a desert some absurdly short time ago, which seems so at odds with the rich ecology of the Everglades - how far did that desert extend, though? Wnt (talk) 16:36, 5 June 2013 (UTC)

• If you look at a map of the deserts of the old world the strongly correlate with areas inhabited by wild goats and our various articles such as on the Gobi mention desertification caused by goats. See also various articles on early (goat, sheep and cattle) domestication and desertification. μηδείς (talk) 00:34, 6 June 2013 (UTC)

June 5

Sodium in softened water

I've been told that home water softeners that don't use reverse osmosis replace the calcium, iron, and magnesium in the water with sodium. (1) is that correct? (2) if that is true, does that put so much sodium in the water that you shouldn't use it for drinking water? Bubba73 ^{You talkin' to me?} 21:01, 5 June 2013 (UTC)

briefly covered in Water softening#Effects of sodium --Digrpat (talk) 22:15, 5 June 2013 (UTC)

Resolved

Thank you - that's what I wanted to know. Bubba73 ^{You talkin' to me?} 22:30, 5 June 2013 (UTC)

Spin in the classical context

I have seen classical fields being referred to as having a spin number, the classical electromagnetic field among them. As far as I can tell, this corresponds to the reciprocal of the period (in full cycles) of the effect of rotation on the field. The electromagnetic field is retored by a rotation of 2π (spin-1), and a gravitational field is restored by a rotation of π (spin-2). This seems to hold, extrapolated to QM fermion fields: a rotation of 4π (spin-1/2). Can anyone point me to the background of this concept in a classical setting? — Quondum 23:02, 5 June 2013 (UTC)

This is certainly true, and certainly classical, but I don't know what reference to point you to. You may want to ask at the math desk.

I'm not sure you were asking about this, but Dirac's equation is the spin−½ massive analog of Maxwell's equations and GR. It's typically given in a form like $i\hbar {\partial \!\!\!{\big /}}\psi -m\psi =0$; to get a classical form without ħ you need to substitute m/ħ = 2π/λ where λ is the Compton wavelength of the field. The QED field equations in Quantum electrodynamics#Mathematics work as a classical theory as well after a similar trick (in which you also need the fine structure constant), and you can even do it to the full Standard Model.

Spin can be interpreted classically in terms of angular momentum as well. E.g. quantum mechanically the angular momentum of a plane wave in the direction of motion is bounded by |L_z| ≤ σnħ where σ is the spin as a half-integer and n is the particle count. If you use another identity like p = nħk to eliminate nħ, you get an inequality that doesn't contain ħ and holds classically. -- BenRG 07:18, 6 June 2013 (UTC)

Thanks, though this approach seems to be trying to squeeze as much classical meaning out of the idea of quantum spin as possible, rather than just finding a classical definition, which various comments I've read (mostly on WP talk pages) led me to suspect existed. I guess I'll have to work through an example of the angular momentum bound of waves satisfying each type of equation. The idea of extending classical elements to the full Standard Model seems intriguing. — Quondum 16:06, 6 June 2013 (UTC)

June 6

What is a Quasi-satellite

When i just first learn quasi-satellite, I don't get it really. On Earth article it said earth has 8000 artificial satellites. Venus only have one temporarily quasi satellite. I don't know if that one body around Venus will crash into Venus. Is their quasi-satelltes or flying asteroids around Mercury. Because few centuries in the future it won't matter if Earth will get swallowed up by sun because technologies are constantly shaping. I hear one proposal is to use flying asteroid to manually move Earth outward which actually can let earth's life last 5-6 billion years longer. I don't know is there flying asteroids around Mercury and Venus, if technologies can alter its orbits. With the nudging effects can it be used with any random asteroids or only quasi-satellites around the parent planets.--69.233.254.115 (talk) 02:42, 6 June 2013 (UTC)

See Quasi-satellite. Bubba73 ^{You talkin' to me?} 02:56, 6 June 2013 (UTC)

I have never heard it before. I just heard quasi-satellite have number code names, because Venus have one temporarily satellites, i don't know is quasi-satellites all temporairly or some of them are permanent. Is there flying asteroids by the sun?--69.233.254.115 (talk) 03:49, 6 June 2013 (UTC)

The solar system is unpredictable on a billion-year timescale; see Stability of the Solar System. For information about near-sun asteroids, see Vulcanoid asteroid and Aten asteroid. Bobmath (talk) 04:41, 6 June 2013 (UTC)

Does time dilate in stationary light clock?

A stationary light clock is shown in the following link in which a light pulse traces out a path of length 2L in between the two mirrors separated by a distance L in the physical space of three linear dimensions.

http://en.wikipedia.org/wiki/File:Time-dilation-001.svg

Although it seems a pulse back and forth in between the mirrors separated by a distance L but in reality the same pulse covered a greater distance than L in its progression of time and therewithal traces out a path equal to the apothem of light cone.

Explanation:

Please click on the animation “A race: There and Back two runners and a time-keeper, a meterstick”in the following link.

http://physics.syr.edu/courses/modules/LIGHTCONE/events.html

If this doesn’t work then click on the following link

http://physics.syr.edu/courses/modules/LIGHTCONE/

Scroll down and then click on EVENTS and SPACETIME of PRIMEVAL RELATIVITY. Scroll down and then start playing animation of “A race: There and Back two runners and a time-keeper, a meterstick”

Let’s the two runners run in between two points A and B separated by distance L. Although they covered a distance of 2L in the physical space of three linear dimensions but in reality [4-dimenional space] it’s not 2L in their world lines as you can see clearly in the animation.

When they start running from point A to B

1- Each runner reaches B diagonally at later (in time) and

Similarly when they starts running from point B to A

2- Each runner reaches A diagonally at later (in time)

This means none of the runners returns to their original position (in past and this impossible) A or B but reach there at later (in time).

Now an example of this animation can give you a quick idea of a pulse moving from A to B and then from B to A in the aforementioned stationary light clock in the physical space of three linear dimensions as well as through space-time if you imagine one of the runners is a pulse.

"Since a pulse never comes back to its original position (past) in its space-time continuum therefore is the distance of 2L appeared in stationary clock authentic and time dilates in aforesaid [stationary] clock?" (Is time dilation / length contraction Real?)162.157.235.1 (talk) 05:05, 6 June 2013 (UTC)Eclectic Eccentric Kamikaze

All of the links you gave above appear to be broken. Dragons flight (talk) 05:30, 6 June 2013 (UTC)

The question seems to have been copy-pasted from here. I fixed the links. However, I don't think I understand the question. The distances like 2L in light-clock-related arguments are distances in 3D space, not 4D spacetime. Diagonal distances in spacetime diagrams (measured with the Pythagorean formula) are meaningless. There is a spacetime "distance", called the spacetime interval, but it's calculated differently and I don't think it's useful here. -- BenRG 07:29, 6 June 2013 (UTC)

Hmmm, this is pushing the limits of Fair Use, without actually being that much use. I'd recommend the OP, or if not then anyone else, do some work to rephrase it. Last thing we need is somebody accusing us of copyvios to go along with all the other crap. Wnt (talk) 17:56, 6 June 2013 (UTC)

Effects of marijuana as a drink

Hi everyone, I was thinking this would be, technically speaking, a medical question, so I've decided to ask here. I was watching an old Indonesian film, Darah Perjaka (1985), which deals with a gang of marijuana dealers who are shipping their product as "tea" (I have no idea if the producers were aware of the English-language slang, but that's not relevant here). The main characters discover that the tea is actually marijuana after someone uses it to brew tea then gets high ("smashed" would probably be a better term, as he was completely out there) after drinking some. Physiologically speaking, would that even have an effect (assuming only one or two glasses of "tea" for a 100 kilograms (220 lb) man)? The marijuana "tea" was mixed with hot water, if that has anything to do with it. — Crisco 1492 (talk) 07:47, 6 June 2013 (UTC)

Check out the article on cannabis tea. 88.112.41.6 (talk) 08:01, 6 June 2013 (UTC)

• WHAOE, alright. Thanks, the answer is right there: "Without proper decarboxylation and preparation of the glandular material, this method of ingesting cannabis yields low psychoactive effects, as tetrahydrocannabinol, the primary psychoactive agent in cannabis, is not a water-soluble compound." Assuming this uncited sentence is correct, the tea in this instance should not have had that kind of effect as it was not prepared specifically as a way of imbibing marijuana. Thanks again. — Crisco 1492 (talk) 08:12, 6 June 2013 (UTC)

Yep, you got it, that sentence is correct. The only caveat I can think of is some people I know brew their (normal) tea looseleaf, and then slurp down the dregs at the end of the cup. So in that case maybe cannabis tea could yield psychoactive effects. SemanticMantis (talk) 14:08, 6 June 2013 (UTC)

• Hmm... didn't pay attention to whether it was bagged or looseleaf (and they certainly didn't show the character drinking the dregs). Thanks for the information. — Crisco 1492 (talk) 14:33, 6 June 2013 (UTC)

I have made marijuana tea (many years ago). It tastes very nasty. You have to mix it with massive amounts of sugar to make it drinkable at all, and even then it's a battle against nausea. (It did get me stoned, though, as I recall.) Looie496 (talk) 14:59, 6 June 2013 (UTC)

• Thus making it even more unlikely that someone could have unknowingly confused it with regular tea. ;) — Crisco 1492 (talk) 15:39, 6 June 2013 (UTC)

I don't know for sure, but I bet that smugglers could purify honey oil from the marijuana and spray it on bulk tea (honest Camilla sinensis) and package it as teabags. I don't know if they would fool a dog, though... Wnt (talk) 17:53, 6 June 2013 (UTC)

Combined cycle plants

What's the difference in general between combined cycle power plants and coal-fired power plants in terms of carbon emmissions? Thanks, 163.202.48.125 (talk) 08:46, 6 June 2013 (UTC)

A new combined cycle natural gas plant generally has around 60% thermal efficiency, while new coal plants are around 40% thermal efficiency. Further, methane has a higher energy content per carbon atom, meaning for the same energy content you expect about 1.6 times as much CO2 from coal as from natural gas. Combining these two effects, and a modern coal plant produces about 2.4 times as much CO2 in order to generate the same amount of electricity as a modern combined cycle gas plant. For the plants actually in use today, rather than new one's with all the best innovations, coal tends to produces about twice as much CO2 per unit of energy as natural gas. Dragons flight (talk) 09:13, 6 June 2013 (UTC)

For some useful followup, try combined cycle power plant, life-cycle greenhouse-gas emissions of energy sources, and fossil-fuel power station. Dragons flight (talk) 09:16, 6 June 2013 (UTC)

Mystery

What is the biggest mystery in science? (Or biggest mysteries) Pass a Method talk 11:07, 6 June 2013 (UTC)

Lists of unsolved problems should give you a start. AndrewWTaylor (talk) 11:22, 6 June 2013 (UTC)

I already knew about that page, but it does not list it in order of importance/significance. Pass a Method talk 11:37, 6 June 2013 (UTC)

Importance/significance is going to be a matter of opinion. We don't do that here. But you are free to make up your own mind. HiLo48 (talk) 12:06, 6 June 2013 (UTC)

And indeed that might be it :-) . {The poster formerly known as 87.81.230.195} 212.95.237.92 (talk) 13:26, 6 June 2013 (UTC)

Its not if you ask "whats the most funded scientific research?" which suggests high demand, or "which scientific mystery is the most quoted in the media and journals?" etc. Pass a Method talk 13:57, 6 June 2013 (UTC)

You can get a feel for the funding levels for broad topics in the USA by browsing the website of the National Science Foundation ( nsf.gov ). You can search past awards by keyword, and if you dig around you can find totals for each section and year. SemanticMantis (talk) 14:05, 6 June 2013 (UTC)

Martin Gardner claimed that the biggest mystery is: Why is there something instead of nothing?

I recall in mathematics there is the Clay Millennium Prizes list. Wnt (talk) 17:59, 6 June 2013 (UTC)

What exactly do service dogs for diabetics detect?

I once saw a boy who had a service pet, a dog, whose job was to let the boy and his parents know if his blood sugar was getting too low by barking or otherwise getting the masters' attention (it was trained to only do so when it should). I wonder, what changes about a human whose blood sugar is getting too low that comes off their body that the dog can detect? Olfactory obviously, but what, is my question. Is there a different chemical in higher or lower than normal concentration in the exhales or perspiration of hypoglycemics? 20.137.2.50 (talk) 15:48, 6 June 2013 (UTC)

Diabetic ketoacidosis#Signs and symptoms Rmhermen (talk) 16:21, 6 June 2013 (UTC)

Right. More generally, low blood sugar leads to ketosis, which results in acetone, a highly volatile compound, being exhaled. Looie496 (talk) 16:26, 6 June 2013 (UTC)

Interesting. The intro paragraph at Diabetic ketoacidosis says "DKA is diagnosed with blood and urine tests; it is distinguished from other, rarer forms of ketoacidosis by the presence of high blood sugar levels." not low. 20.137.2.50 (talk) 16:33, 6 June 2013 (UTC)

Just a stupid thinko on my part -- I meant low insulin, not low blood sugar. Note though that ketoacidosis is an extreme form of ketosis. By the time ketoacidosis has set in, the dog has already failed to do its job. Looie496 (talk) 16:43, 6 June 2013 (UTC)

Ah, OK. Then I remembered wrong too. So the dog does not bark necessarily when the blood sugar gets too low; it barks when insulin levels get low, which probably more often coincides with higher blood sugar. 20.137.2.50 (talk) 16:51, 6 June 2013 (UTC)

Guys, you're floundering here - this is one of those cases where our many critics would say we outta be bringing references to the question, and this one is not hard to look up! Don't come to the party without bringing something!

According to [11] , " Our dogs are trained using scent detection techniques to identify changes that occur in human body odor when blood sugar levels move above or below normal ranges. " Which is certainly believable - either condition is a major alteration in biochemistry. Wall Street Journal agrees, and says that research is ongoing to find the odorants, which means I assume at least then they weren't known. [12] Wnt (talk) 17:49, 6 June 2013 (UTC)

Interesting. Here at the volunteers section of that site you linked to, it asks people with insulin dependent diabetes to offer scent samples by wiping their forehead with some gauze and measuring their blood sugar, which indicates that what the dog's taking can come out of the person's skin. 20.137.2.50 (talk) 18:08, 6 June 2013 (UTC)

Hail and windscreens

Is it useful to put a finger in your windscreen during hail to prevent it for breaking?--90.165.116.251 (talk) 15:51, 6 June 2013 (UTC)

No. --Jayron32 18:15, 6 June 2013 (UTC)

Especially if you are driving! SemanticMantis (talk) 18:33, 6 June 2013 (UTC)

I suppose the thinking here is that your finger might dampen out vibrations and thus remove energy from the system. I could maybe imagine that helping in some manner - but I doubt by very much. SteveBaker (talk) 19:20, 6 June 2013 (UTC)

I didn't touch this one because I can't imagine how you'd begin to figure out the answer. Any ideas? I suppose somebody tests windshields against hail - plenty of stuff comes up in a search. It looks like many of the impacts in images (but not all) have quite localized damage though, which makes me wonder how much a finger matters if it isn't right in the path of the hail ... not sure if having it in the path of the hail is something to recommend, either. But someone has to know some theory about it. Wnt (talk) 19:45, 6 June 2013 (UTC)

Geometric Optics (Refraction)

Hello! I am a grade 10 student who received a physics quiz (on geometric optics) back recently, and I am having a bit of dispute with two true-or-false questions.

The first, which is likely very open to interpretation, is, "A light ray is either reflected or transmitted when it strikes a surface such as a piece of glass." This particular chapter is on refraction of light, and I said false, arguing that (1) in this particular situation it should be "reflected or refracted" instead of "transmitted" and (2) in some (if not most) situations, can't glass do both?

The second, "Blue light bends more than red light, so blue light travels slower than red light." I said true, because in a note (incidentally straight from the textbook) it said, "Dispersion occurs because each colour of visible light travels at a slightly different speed when it goes through the glass prism. Violet light slows down more than red light when it enters the prism. That is why you see violet light being refracted more than any other colour (that is, bending more toward the normal than any other colour). Red light is refracted the least" (bold for emphasis). Since blue is closer to violet than red, I said it was true.

It was just a quiz, but it means the difference from an 89% to a 95% :P. Was I right? Was I wrong? Thanks for your input! 174.93.65.84 (talk) 20:27, 6 June 2013 (UTC)