Wikipedia:Reference desk/Archives/Science/2011 March 7

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March 7

Reactions with super-heavy elements?

Hi there, just wondering if any reactions have been done with super-heavy elements that have long enough half-lives. (I'm guessing this would be done to see if they have similar properties to other elements in their respective groups.) If so, what reactions have been done and what been the outcomes? I'm also wondering if there is good reason for trying to create 'new' elements e.g. Element 119, i.e. are scientists looking for anything in particular, or is it just done in case these elements can be used in the future for something? If that is the case, what are the expected applications of these super-heavy elements? I've had a good search of Wikipedia but can't really find anything to help so any answers or thoughts would be much appreciated. Kind regards, Raywil (talk) 03:17, 7 March 2011 (UTC)

Island of stability. ~AH1^(TCU) 03:21, 7 March 2011 (UTC)

Many thanks for the reply: I know about the island of stability but didn't realise that the article described the potential applications of elements that make up the island. Now for the rest of my questions... Raywil (talk) 04:02, 7 March 2011 (UTC)

Thought I'd give this a sort of "bump" to see if anyone else has answers. Thanks. Raywil (talk) 22:49, 7 March 2011 (UTC)

I don't think practical (chemical) applications are likely, any time soon, since the cost of such lab-made chemical elements is likely to be prohibitively high. StuRat (talk) 17:48, 8 March 2011 (UTC)

Also it's too early to answer those questions. Till we make macroscopic amounts of those elements it's pretty hard to figure out applications for them. As for why they are making them, it's mainly curiosity, but also, maybe there will be some awesome application. No way to know till you (they) try. Ariel. (talk) 21:33, 8 March 2011 (UTC)

Many thanks for your thoughts; much appreciated. Raywil (talk) 19:15, 9 March 2011 (UTC)

The highest temperature

Is there any point such as kelvin zero for highest temperature?a. mohammadzade iran--78.38.28.3 (talk) 04:10, 7 March 2011 (UTC)

No.--Srleffler (talk) 05:26, 7 March 2011 (UTC)

You could consider -0 (negative zero, or zero approached from the left) to be the highest temperature, which like absolute zero, is unachievable. See negative temperature. Although depending on the system, positive infinity could be the actual maximum (and unachievable) temperature. Someguy1221 (talk) 07:18, 7 March 2011 (UTC)

A rather poor article but perhaps Absolute hot may be of interest. Nil Einne (talk) 10:24, 7 March 2011 (UTC)

By the current theories, temperature is the measure of the average speed of the particles. An approximate formula is $T={\frac {v_{avg}^{2}\pi M}{8}}$. (M is molecular mass). By this definition, you can have absolute zero with molecules of avg speed zero. Now, your maximum speed is the speed of light, and you can maximize temperature by plugging it in, but, this is the maximum temperature for a molecule with given molecular mass. Take a bigger molecule, and your temperature increases. So there's no maximum temperature. ManishEarth^{Talk • Stalk} 12:16, 7 March 2011 (UTC)

It's almost never a good idea to 'plug in' the speed of light if you're not very sure of the assumptions underlying a formula. Temperature is a measure of the average thermal energy per particle, which for a gas under reasonable conditions is roughly proportional to the average kinetic energy per particle. In classical mechanics, the kinetic energy of an object is proportional to its mass, and increases with the square of its velocity; that's were the v² term comes from in the equation you've used. This falls apart when you get to temperatures high enough that special relativity rears its ugly head. As you put more kinetic energy into a particle in order to increase its velocity, there will be an associated increase in its relativistic mass. The effect is negligible at any reasonable velocities and temperatures, but the particle's mass (and its kinetic energy) will asymptotically approach infinity as you bring its velocity closer and closer to the speed of light. Any hypothetical molecule travelling (impossibly) at the speed of light would have an infinite kinetic energy and therefore an infinite temperature. TenOfAllTrades(talk) 13:59, 7 March 2011 (UTC)

Indeed not only that but the aforementioned equation is missing a Boltzmann constant, and if true, would imply and absolute hot, as there exists only a finite mass; but alas, it is all irrelevant.— Preceding unsigned comment added by 129.67.37.227 (talk • contribs) 23:50, 7 March 2011 (UTC)

More importantly, the basic statement is wrong. Temperature is not a measurement of the average speed of the particles.

This is something that needs to be emphasized every time it comes up. The direct relationship between temperature and kinetic energy works only in one very simple, idealized case — an ideal gas made of individual particles (at normal temperatures, this means a monatomic element like helium or neon). In all other cases, the relationship breaks.

What temperature really is is a statistical concept. It's not about kinetic energy per se. --Trovatore (talk) 00:03, 8 March 2011 (UTC)

Temperature, despite the fact that we use it every day, really IS a very hard concept to get at. Personally, I find the explanation afforded by the Zeroth law of thermodynamics to be most satisfying; the general concept that temperature is defined in terms of thermal energy transfer; two bodies are empirically defined as the same temperature insofar as they are in thermal equilibrium; the temperature at any equilibrium can then be defined as dH/dS, (or dq/dS if you prefer) the relationship between heat and entropy at a particular thermal state. --Jayron32 06:24, 8 March 2011 (UTC)

See a previous discussion at: Wikipedia:Reference desk/Archives/Science/2009 July 14#The Limit of heat?. Staecker (talk) 13:22, 7 March 2011 (UTC)

You might say "absolute zero". Minus absolute zero, that is! See negative temperature. But that is a specialized usage of the idea. Wnt (talk) 05:50, 8 March 2011 (UTC)

exploding of supernova

how dos explode a supernova and how will be the fragment of its inner matter i couldn't find perfect explanation of this in encyclopedia. akbar mohammad zade iran march 2011--78.38.28.3 (talk) 04:18, 7 March2011 (UTC)

In existing nebula if the star matter be powder and dust or it remain molten?a. mohammadzade--78.38.28.3 (talk) 04:23, 7 March 2011 (UTC)

A supernova explodes when the core of a star collapses, causing extremely high pressures. These pressures cause the star to "bounce" back, blowing it to bits.

Stars are made mostly of hydrogen and helium, and the core of a star gone supernova has some carbon, oxygen, silicon, magnesium, and iron. Many of these are gases at most temperatures and pressures, and in the vacuum of outer space, most of them will be gases. Does this answer your question? --T H F S W (T · C · E) 04:53, 7 March 2011 (UTC)

thanks i think that might have gathered pieces ,then this gathered pieces will be molten, because of its condensed early condition and first density what have been observed in crab nebula .if that be gas then in which density?and how can it have 11000 degrees temperature?a. mohammadzade --78.38.28.3 (talk) 05:23, 7 March 2011 (UTC)

The density is very low - the only reason we're able to observe it, is because the nebula is so big. The temperature of the nebule is a measure of the average thermal energy per particle. (molecule, atome, etc.) Since the nebula is so sparse, an observer located inside the nebula would not notice a difference in temperature compared to outside the nebula. Plasmic Physics (talk) 10:06, 7 March 2011 (UTC)

To help to explain this, think of putting your hand into an oven at full temperature. If you touch something dense inside, like a pot, your hand would burn instantly. If you only touch the less dense air, then your hand heats up more slowly, and you might be able to take a few seconds without getting burnt. Now imagine that the air is a trillion times less dense, and your had wouldn't get hot at all (except for radiation from the sides of the oven, but we'll ignore that). StuRat (talk) 17:38, 8 March 2011 (UTC)

Petrochemical Distallation

Is it possible to sort a mixture of waste plastics using fractional distallation under an anoxic atmosphere? Plasmic Physics (talk) 09:56, 7 March 2011 (UTC)

In general, no, because plastics tend to decompose when heated, producing hydrocarbons and other products. You may get useful fuel out, but not gaseous plastic that you can then condense and reuse.[1][2][3][4] --Colapeninsula (talk) 11:51, 7 March 2011 (UTC)

Would increasing the pressure to several times atmospheric pressure have any effect on the rate of pyrolysis? Plasmic Physics (talk) 22:21, 7 March 2011 (UTC)

Where are the batteries on this bike?

Where does the energy come from for this? http://www.bbc.co.uk/news/uk-england-10858682 I cannot see any batteries. Can anyone explain what this is supposed to be doing? Thanks. 92.29.124.221 (talk) 12:42, 7 March 2011 (UTC)

They're in the pedal. You can see them on the video - they're the two objects on either side of the pedal, wrapped in a black shrinkwrap. The pedal has had a motor and batteries added. Assuming the user resists the attempt of the pedal to turn, the pedal and foot combined will drive the crank. --Tagishsimon (talk) 12:48, 7 March 2011 (UTC)

Thanks. I expect batteries that small will last about two minutes, so they are practically useless. 92.29.124.221 (talk) 12:52, 7 March 2011 (UTC)

They probably didn't developed the bike to be run all the time with these tiny batteries, but only to give you an added push. 80.58.205.34 (talk) 16:36, 7 March 2011 (UTC)

Excavations at ancient battle sites

What are the odds of finding the helmets, shields etc and human remains at the sites of ancient battles (such as Thermopylae)? Also I'm curious what would be the depth of digging to reach the weaponry and human remains in case of Thermopylae? —Preceding unsigned comment added by 89.76.224.253 (talk) 14:42, 7 March 2011 (UTC)

Just to note here that the helmets, shields and such would have been recycled by the victors and so you wouldn't have much chance of finding them. In Repton, UK, a number of male skeletons were found near the parish church in the last century, and it is speculated that these were victims of a Dark Age skirmish.Repton Church --TammyMoet (talk) 15:21, 7 March 2011 (UTC)

Just to be clear, what you're referring to is looting and/or grave robbery (depending on the circumstances) and is considered unethical and/or illegal depending on the jurisdiction. Unfortunately, the illegal antiquities trade has been going on since the "antiquities" were brand new, meaning that many, if not most, archaeological sites have been pretty seriously plundered of what non-archaeologists would consider valuable (cool stuff like weapons are in almost a high demand as the shiny stuff). I don't know the depth of the soil at Thermopylae, but our article at least indicates that the water levels have dropped since the battle took place, so at least they won't be underwater. Matt Deres (talk) 17:51, 7 March 2011 (UTC)

I think many other people have thought about this in the past and the likelihood of finding any remains now is, well, slight, and that's being optimistic. 86.4.187.76 (talk) 20:42, 7 March 2011 (UTC)

Technically, it's not unethical to dig up ancient artifacts and treasure; it's only unethical for poor people to profit from them, rather than license-holders and established institutions. Wnt (talk) 00:58, 8 March 2011 (UTC)

I'm sorry, but that's just incorrect; the problem has nothing to do with who profits, it's with what happens to both the artifacts and the state of the site. The people who raid such sites just dig holes all over, grab whatever they figure they can sell, and make off with whatever they can carry away, paying no attention to recording provenience of the pieces, horribly contaminating the site and artifacts to render most dating techniques unreliable, and literally destroying whatever gets in their way of making a buck. The pots and jewellery and neat looking human remains get sold off and lost from the archaeological record, to the detriment of everyone. Matt Deres (talk) 04:20, 8 March 2011 (UTC)

Just like to point out, the person asking didn't say they were going to dig up battlefields, they just asked a hypothetical question about what might be found at old battlefields. There's no need to get on your soapboxes, people. Pretend he/she is an archaeologist. --Colapeninsula (talk) 10:35, 8 March 2011 (UTC)

No soap-boxing intended. The OP's specifications on looking for the "cool" stuff are highly indicative of someone who isn't planning a proper dig. Not that I think they're actually planning on flying over with a pickaxe to start treasure hunting, but I wanted them to at least be aware that it's unethical (and usually illegal) to do so. Matt Deres (talk) 14:13, 9 March 2011 (UTC)

I wonder; if helmets, armor, shields, and weapons were there, if they would be totally corroded by now. I believe the Battle of Thermopylae occurred during the Iron Age, so it may have all rusted away, by now. Perhaps some high ranking soldiers might have had some gold accents on their items, but then those would have been even more likely to have been stolen. StuRat (talk) 17:26, 8 March 2011 (UTC)

Iron and bronze can indeed rust away, but that doesn't mean that nothing can be gained from it. In a proper excavation, even artifacts which have nominally been rusted away can still provide information by way of the rusty stains they leave in the soil. Estimates of counts, the metals used, the size and kinds of implements left behind, and more, can all be inferred from examining the soil closely. That could then be compared against other sites to provide evidence of changes in material culture, advance in metallurgy , and trade routes. Provided that someone hasn't dug the entire site up looking for a cool skull to stick on their mantle. Matt Deres (talk) 14:23, 9 March 2011 (UTC)

Budgerigar 'charming'?

How/why does this work? I think that this effect, or something like it has been discussed on here before in relation to other bird species. The guy in the video is a real veterinarian, who also has some 'mystic' beliefs which he draws on, alongside the traditional medicine (AFAIK) - but I'm personally sceptical that this is actually a 'mystic' phenomenon. Something is clearly happening here though, to render the budgie still and docile. Any ideas? --95.148.106.17 (talk) 15:10, 7 March 2011 (UTC)

He also does the same thing with a lovebird here while trimming its beak. --95.148.106.17 (talk) 15:16, 7 March 2011 (UTC)

Interesting.. Wonder if it is something similar to Chicken hypnotism.. That's what really annoys me about stuff like this, there's obviously something very cool and interesting going on and then he has to go and say that he's seen John of God do it to people who then have surgery standing up without anaesthetic, what a crock. Vespine (talk) 00:37, 8 March 2011 (UTC)

This one is even more extraordinary. It certainly seems woo-ish from the way he describes it - but he's obviously doing *something* that works. A parrot flipped on its back would normally bite (hard) and struggle to escape. --Kurt Shaped Box (talk) 02:23, 8 March 2011 (UTC)

Parrots peacefully scattered around in the landscape on their the backs (drunk) isn't an unusual sight in Queensland so they seem to have a "I'll just have a bit of a lie down for a while" mode. Sean.hoyland - talk 17:41, 8 March 2011 (UTC)

I can think of two triggers that might calm a bird:

1) The "time to sleep" trigger might occur when the light level goes down, such as covering the eyes (or entire cage) of a diurnal bird. This doesn't seem to have been used, in this case.

2) The "preening" trigger might occur in social birds, where they are preened by others. This might apply here, as stroking of the feathers may set this off. Thus, those birds which calmed down, when being preened by others, might have been more likely to survive and pass on their genes than those that became agitated. Do budgies preen each other ? StuRat (talk) 17:10, 8 March 2011 (UTC)

I'm actually not very impressed with this video. The bird tries to get away again and again and again, and he has to hold its wing awkwardly at one point to contain it. It's not obvious to me that a bird has to struggle to escape continuously, as opposed to once a minute as this one does, especially not when it's an old arthritic bird that has lived most of its life in a cage. It is apparent, of course, that the feel of a hand around its wings and/or being upside down has some effect, but this is scarcely magical. It reminds me of something from mouse work - supposedly, holding the mouse by the scruff of the neck keeps it from trying to get away when injected, but honestly, I suspect that any pain equivalent to such a pinch makes the mouse briefly play possum (or otherwise stop moving), and the specific technique is unimportant. Wnt (talk) 22:53, 8 March 2011 (UTC)

I believe the grabbing by the scruff of the neck is a method used by some mammal moms to carry their young with their mouth. I've seen it used on kittens. I believe this is another of those automatic signals that causes them to go limp, as kittens that struggled might have been left behind and died, while those that went limp survived to pass on their genes. However, I don't think this applies to any birds, since they don't carry their young in this manner. StuRat (talk) 10:46, 9 March 2011 (UTC)

I seem to recall reading somewhere (about 542 years ago?) that signficant pressure applied to the skin and soft tissues on the scruff of the neck of an animal induces the release of a bolus of endorphins and other, similar compounds into the bloodstream of the animal, generating a calming effect. If you would like me to find a recent reference, hit me up on my Talk page. CAVEAT: I've tried this with my wife when she becomes enraged with me, but it doesn't seem to work very well :-O

Best regards:

Cliff L. Knickerbocker, MS (talk) 13:35, 12 March 2011 (UTC)

Acrylamide in commercial breads

I buy 100% Whole Wheat breads from supermarkets, and try to purchase as few sugars as I can, but I'm not sure if anything can be done about acrylamide. Is making my own bread by boiling the only way to avoid the substance? (And no, I don't believe epidemiological studies.) Imagine Reason (talk) 19:08, 7 March 2011 (UTC)

How does one boil a bread? Dauto (talk) 19:55, 7 March 2011 (UTC

A bread what? I think we usually call it a loaf or a roll (or bap) 86.4.187.76 (talk) 20:40, 7 March 2011 (UTC)

Bagels are boiled. Ariel. (talk) 20:49, 7 March 2011 (UTC)

The idea with boiling is the temperature, not the actual boiling. All you need to do is cook the bread till it's cooked, but not browned. So avoid a heavy crust, and take it out when it's still pale. You should also make smaller bread, so the inside is fully cooked without having to heat the outside very much. If you are really worried, then cut off the crust. The inside of bread doesn't really go much above boiling (if it did it would dry out and become crust). Ariel. (talk) 20:49, 7 March 2011 (UTC)

So maybe picky children (who want their PB&J with the crusts cut off) were right all along. StuRat (talk) 18:30, 8 March 2011 (UTC)

I've noticed various brands of crustless bread in the supermarket - some new process, I think. 81.131.26.97 (talk) 04:44, 8 March 2011 (UTC)

I assumed they just cut the crusts off and used it for other things, like bread crumbs or animal feed. StuRat (talk) 18:30, 8 March 2011 (UTC)

I tried two brands: one seemed to have the crusts cut off as you say, the other had a thin layer of dense but pale bread instead of crust. 213.122.24.251 (talk) 23:44, 8 March 2011 (UTC)

I investigated this myself in the past. There is such a thing as steamed bread, and there are steamed bread rolls which are a Chinese thing.

I've never seen either of them for sale anywhere, but if steamed bread was done at high pressure it may be no better than ordinary bread. Steamed bread redirects to Chinese steamed rolls. Frying them as the article shows would introduce acrylamide into them.

Wholemeal bread has more acrylamide in it than white bread. Soda-bread has less acrylamide in it. Since acrylamide is associated with browning (by heat, not enzymic browning) then pale un-browned bread such as some pitta bread is likely to be safer. Any manufacturer who can supply acrylamide-free bread will make a fortune. By the way, crispbreads have very very large amounts of acrylamide in them. Cooking food in a microwave also results in acrylamide.

I'd be very interested to learn of any practical recipies for home-steamed bread or even rolls. 92.29.127.85 (talk) 20:53, 7 March 2011 (UTC)

Boston brown bread or hobo bread. Rmhermen (talk) 00:19, 8 March 2011 (UTC)

Thanks. The three and a half hour cooking time is something to think about, although on the other hand my bread machine takes longer than that. 92.15.0.66 (talk) 16:25, 8 March 2011 (UTC)

As an aside, the acrylamide scare is the unwarrented-panic-du-jour. If it is present in baked starchy goods, then it has been there for thousands of years, or roughly as long as humans have been baking bread. Whether or not, and at what levels, it is carcinogenic isn't nearly as important as the measurable health outcomes of consuming acrylamides on baked goods such as breads. In other words, does the eating of bread have a measurable impact on your likelyhood of dying of cancer, solely from the acrylamide content? How many cancer cases per year can be traced to acrylamide consumption from ordinary baked goods? I think you'll find these numbers to be vanishingling small, close to zero. On the list of risks to your own life, in terms of both length and quality, eating whole grain bread falls somewhere near the bottom. --Jayron32 04:58, 8 March 2011 (UTC)

Our physiology has evolved for many millions of years since the beginning of life. We only started cooking bread very recently. Evolution is not very sensitive to early deaths after you've had kids. 92.15.0.66 (talk) 16:23, 8 March 2011 (UTC)

We've been drinking alcohol for a long time, too. Ok, so it's much safer than beer, but we've been ignorant for most of our history. 66.108.223.179 (talk) 14:31, 8 March 2011 (UTC)

The Romans did not live very long because they were unwittingly poisoning themselves from the lead in their pipes and drinking vessels. I think they may also have added it to wine, not sure. They did not detect it was poisonous because everyone was consuming it. Before acrylamide was found in food, it was classified as a probable carcinogen. Now that its been discovered in food, then all of a sudden it becomes harmless? Can I remind you that a large proportion of people (do not recall exact proportion) die of cancer. So, probable carcinogen in food, and lots of people dying of cancer - surprised? 92.15.0.66 (talk) 16:12, 8 March 2011 (UTC)

Yes, it could be a problem, but we need more info to know if it really is a problem. That is, just how carcinogenic is it ? It would be impossible to avoid all carcinogens entirely, as you likely inhale several with every breath. So, then, since we can't avoid all carcinogens, the issue becomes avoiding the worst ones. StuRat (talk) 16:53, 8 March 2011 (UTC)

"Just how carcinogenic is it" you ask. "The European Chemical Agency added acrylamide to the list of substances of very high concern in March 2010.[5]". 92.15.20.212 (talk) 17:50, 8 March 2011 (UTC)

Your footnote didn't copy, do you have a link ? StuRat (talk) 18:26, 8 March 2011 (UTC)

Go to the Acrylamide article and find footnote number 5. 92.15.20.212 (talk) 20:56, 8 March 2011 (UTC)

OK, following the link I found a study that showed no evidence of it causing cancer in humans, but they did find it caused cancer in rats when given at the rate of 3 mg per kg of body mass per day. So, then, the question is whether the amount in bread comes close to that. I didn't find info for bread, but this site lists the level as 1.57 mg/kg for French fries ("chips" in British English): [5]. However, this is per kg of food, not per kg of body weight. So, you'd need to eat twice your weight in fries each day to have the same exposure level as rats had in the study. If bread has comparable levels, then the results should be similar. StuRat (talk) 22:41, 8 March 2011 (UTC)

There is "no evidence of it causing cancer in humans" because no one would do such an unethical experiment. The mice would have been fed acrylamide for a short time (they only live a year or two, maybe less) which is not the same as eating it over more than fifthy years for a human. The mice can show it is carcinogenic to mice and by inference mammals, but the dose in relation to bodyweight cannot be extrapolated due to the different time-scales inolved. 92.24.191.116 (talk) 23:46, 8 March 2011 (UTC)

They had results of 2 studies from chemical factory workers who had been exposed, but they showed no signs of any problems. Mice have much faster metabolic rates, which should cause them to show signs of cancer far quicker than in people. StuRat (talk) 04:07, 9 March 2011 (UTC)

I think you've misunderstood that. The study that resulted in acrylamide in food being discovered was a study of the workers in a factory that dealt with a lot of acrylamide. The big surprise was that the control group (people who did not work at the factory) had just as much acrylamide in them as the factory workers. You say "no signs of any problems" yet as said above, lots of people are dying of cancer all the time. The number of everyday things once assumed to be harmless but now believed to be carcinogenic is slowly increasing: for example cigarettes and asbestos. What's next?

Some third-world and other countries have much lower cancer rates than europe and north America. They could be countries were lower amounts of acrylamide are consumed, due to different customary diets. I'd be interested to read any cross-cultural study of acrylamide consumption.

You say "mice have much faster metabolic rates". The only thing that would speed metabolic chemical reactions would be a higher temperature. I don't think the body temperature of mice is much different from humans, particularly when considered on an absolute Kelvin scale. They are not red-hot. I do not think their slightly different temperaure would compensate for their lifespan of a year or two compared to the 50 to 100 years of humans. 92.28.254.54 (talk) 13:24, 10 March 2011 (UTC)

If the cancer develops by mutating a gene when a cell duplicates, then it will happen quicker if the cell duplicates more often, much as happens in animals with faster metabolic rates, like mice. As for there being less cancer in third world nations, that just because they die of war, malnutrition, and infectious diseases before they get old, when cancer is more prevalent. Also, while everyone may be exposed to some, the factory workers were exposed to much more, so should have shown increased mortality, if it really was dangerous at those levels. StuRat (talk) 02:13, 12 March 2011 (UTC)

There's no reason to think, apart from your imagination, that cells divide more frequently in small adult animals than large ones. You make assertions about cancer in the third world, but what evidence is this based on? Your imagination I presume. As far as I recall the factory workers and the control had similar amounts, so the factory was not contributing much. 92.15.6.232 (talk) 11:10, 12 March 2011 (UTC)

If you will tell me which part you doubt, then I will be glad to provide proof:

A) Cancer is more prevalent in the elderly.

B) Third world nations have fewer elderly people, as a percentage of their populations. StuRat (talk) 22:11, 12 March 2011 (UTC)

I wish you'd stop speculating all the time, the repetition is boring. OK, please quote the statistics that lead to your conclusions regarding 3rd. world cancer. Or could they be all in your imagination? 92.24.190.23 (talk) 22:32, 12 March 2011 (UTC)

You failed to tell me which part you doubt ? Is it A or B ? StuRat (talk) 22:39, 12 March 2011 (UTC)

You've avoided quoting any stats as requested. Where are they? Why cannot you provide them? I believe its customery and rather obviously required to compare cancer rates of populations at the same ages. I cannot see how listing a couple of platitudes has any significance. 92.15.8.206 (talk) 22:59, 12 March 2011 (UTC)

OK, then, let's see your proof that cancer rates are lower in 3rd world nations, when adjusted for age. You are the one who made the claim, not me, so you prove it. StuRat (talk) 23:16, 12 March 2011 (UTC)

As I wrote above: You've avoided quoting any stats as requested. Where are they? Why cannot you provide them? Stop trying to change the subject. Boredom, lazyness and the time of night here disincline me to search for that on Google. 92.15.8.206 (talk) 00:13, 13 March 2011 (UTC)

As for mice having a higher rate of cell division: "...metabolic rate and the rate of germ-cell division increase in smaller species...", from [6]. Now, if you are going to accuse me of "speculation", I will do the same to you. You can start by proving that cancer rates and acylimide consumption are lower in third world nations. StuRat (talk) 22:11, 12 March 2011 (UTC)

That paper is mainly about DNA maintenance and DNA evolution. Where does it say that the cells of small animals divide more frequently that those in large animals? Cannot see that anywhere. It says that smaller animals use more oxygen per unit weight, but you'd expect that as they have more surace area per unit volume so they have to burn more energy to maintain their body temperature. In any case, knowing oxygen usage per unit weight is a very very long way from allowing you to calculate the comparative dosage lethality of mice and men. 92.15.8.206 (talk) 22:59, 12 March 2011 (UTC)

Last sentence on page 4090. StuRat (talk) 09:20, 13 March 2011 (UTC)

Note that it could still be highly carcinogenic if you have a bottle of it, and yet be completely insignificant as a food safety risk, if the quantity in bread is small enough. For example, ozone is also a health risk, but the amount in the air we breath is typically low enough that it's not a concern. Only when we have elevated levels, as in cities with a pollution problem, do we need to do something about it. StuRat (talk) 18:35, 8 March 2011 (UTC)

OK, tell us, how little is harmless? How many scientists do you have working at the StuRat Laboratories? You must have a secret underground headquarters like Dr. No in James Bond. 92.15.20.212 (talk) 20:56, 8 March 2011 (UTC)

I don't have time to respond to that...I'm too busy petting a cat with one hand and adjusting the calibration on my missile launcher with the other. StuRat (talk) 23:11, 8 March 2011 (UTC)

It could be that there is no lower safe limit. 92.28.254.54 (talk) 13:24, 10 March 2011 (UTC)

Not really. The only way a single molecule could kill you is if it can reproduce and your immune system had no protection from it. And if one molecule could kill you, then all the people who ever ate burnt bread would drop dead immediately. Even the most dangerous substances almost always have some level of safe dosage. Many poisons are even given as meds (in a safe dosage, of course), like warfarin. StuRat (talk) 02:45, 12 March 2011 (UTC)

"And if one molecule could kill you, then all the people who ever ate burnt bread would drop dead immediately." I understand that cancers take 10 -20 years or more to kill you, so that dosnt make any sense. 92.24.190.23 (talk) 22:41, 12 March 2011 (UTC)

OK, they would drop dead in 10-20 years, then. That still doesn't happen, does it ? StuRat (talk) 23:17, 12 March 2011 (UTC)

How do you know? 92.15.8.206 (talk) 00:03, 13 March 2011 (UTC)

A single molecule of plutonium might be effective. With cancer-causing chemicals, the less chemical the less risk, but a single molecule would still have a small risk. 92.15.6.232 (talk) 11:06, 12 March 2011 (UTC)

A single atom of plutonium wouldn't cause much harm. We are constantly bombarded with radiation from external sources, which would far outweigh that one atom (get a Geiger counter and listen to all the clicks, some time). As for increased risk, when you get to the point where, if everyone on Earth had that level of exposure, not one of them would be likely to show any effect, that's no longer worthy of being considered an "increased risk". It would also cause many deaths to spend scarce resources to eliminate such a minuscule risk, when those resources could be better spent to reduce major risks, which kill millions each year, like smoking. StuRat (talk) 22:17, 12 March 2011 (UTC)

"A single atom of plutonium wouldn't cause much harm." Please give the research papers that provide the evidence for that conclusion - imagination dosnt count. 92.24.190.23 (talk) 22:37, 12 March 2011 (UTC)

The fact that we already have far more than on atom of plutonium is pretty good evidence that any one doesn't do much harm. I don't think you appreciate just how many atoms are in the human body. There are so many that pretty much some of any naturally occurring element is bound to be present. At this site they ran various calcs, and the lowest result was that the average human body would have about 197 atoms of plutonium: [7]. StuRat (talk) 23:42, 12 March 2011 (UTC)

It's not "pretty good evidence" at all. You can make an analogy with asbestos and asbestiosis (sp?) - the risk increases with exposure, but even people who have had a tiny exposure may sometimes get it. 92.15.8.206 (talk) 00:13, 13 March 2011 (UTC)

You know what? Instead of using the whole number scale, I think your reasoning is based on just three "numbers": more, same, less. Or perhaps: lots, average amount, small amount. Fascinating! 92.15.8.206 (talk) 23:06, 12 March 2011 (UTC)

I'm still waiting on proof that anything YOU say is anything beyond wild speculation. StuRat (talk) 23:46, 12 March 2011 (UTC)

Bad loser, lol! 92.15.8.206 (talk) 00:16, 13 March 2011 (UTC)

See also Post hoc ergo propter hoc. AndrewWTaylor (talk) 17:03, 8 March 2011 (UTC)

1. Everybody dies. 2. Death always has a cause. Given that "1" and "2" are self evidently true, IMHO, eating well is a higher priority than going to extreme weirdo paranoid lengths in a probably futile attempt to avoid just one of the practically infinite number of causes of death, particularly if that one happens to be responsible for a vanishingly small proportion of the total number of (human) deaths that have ever occurred. Don't sweat the small stuff, live well, die happy. Roger (talk) 20:17, 11 March 2011 (UTC)

Cleaning bones

Hello. I have some friends who found a coyote skull, broken into four pieces. I was thinking of gluing them together and making a stand for a nice display, but I need it cleaned first, and I need some small, invertebrate help to do it. If I were to put it in a terrarium with either mealworms or crickets for a while, would they get it all nice and clean for me, similar to Dermestidae beetles? --T H F S W (T · C · E) 19:25, 7 March 2011 (UTC)

Amazingly, we have already answered this question on the Reference Desk. See "Help Cleaning a Dog Skull" from May 2008, and "Part Two" of the same. Nimur (talk) 19:32, 7 March 2011 (UTC)

This subject actually comes up a lot - Rabbit, February 2008 (discussion regarding the use of beetles)... Nimur (talk) 19:39, 7 March 2011 (UTC)

Thank you, the above links were helpful, but you still did not answer my question: could I use either mealworms or crickets to clean a skull without damaging it? --T H F S W (T · C · E) 23:20, 7 March 2011 (UTC)

Crickets are omnivores and will apparently eat decaying organic matter. Our mealworm article indicates that they prefer vegetarian fare, so I'm unsure if they will be useful for cleaning your specimen. Previous responses have suggested ants. Nimur (talk) 00:06, 8 March 2011 (UTC)

(Edit Conflict) The articles to which you have already linked both suggest that these insects are primarily herbivores that may eat insect remains if that's all that's available, but do not mention any propensity for eating mammalian organic remains, which seems to me unlikely as it's far from their normal diet. You could simply try them both out - the bones are not going to suffer if either or both don't perform, and you can then try one of the other methods.

You might find some useful information in this post. 87.81.230.195 (talk) 00:07, 8 March 2011 (UTC)

(EC)Hmm, i'm not an expert but I don't think so. crickets and mealworms mostly eat vegetable matter, not decaying meat.. I just use flies and ants. if you have any "yard", buy a cheap bucket, put some holes in it, cover the skull and put a brick on it so a cat or something can't drag it off. Vespine (talk) 00:08, 8 March 2011 (UTC)

Also, if it gets to the stage where you are gluing it back together, I read that bone collectors use regular PVA glue: It's transparent, doesn't damage the bones, bonds well enough and can be washed off if required. Vespine (talk) 00:10, 8 March 2011 (UTC)

Hmmm. Is there anything wrong with your standard housefly/bluebottle maggots? Or how about simply boiling the skull? --Kurt Shaped Box (talk) 00:09, 8 March 2011 (UTC)

Normal house flies would take too long and the place would stink while they did their work (If THFSW is in the northern hemispeher, there also might not be many flying around at this time of year). Boiling the skull would be quick, easy, and thorough, so long as you don't mind a little grossness. FYI, the bones might not fit back together as neatly as you might hope; in living animals, the bones can bend slightly before breaking - if this critter was hit by a car or something, you might end up with a skull that looks warped or deformed. Matt Deres (talk) 01:08, 8 March 2011 (UTC)

I haven't actually seen the skull, some friends of mine found it. i don't know about the condition, it might not even be worth it to try to piece it together again. Just one question: will boiling the skull (sounds barbaric!) get rid of all the flesh and dirt? I think that this skull may have been underground for a long time, so cleaning it may be the only issue. --T H F S W (T · C · E) 05:30, 8 March 2011 (UTC)

In my experience, boiling in water alone will remove dirt but not all the flesh. The flesh does become softer and easier to remove, after many hours of boiling, and the skin and muscles fall off, but other parts remain attached, including cartilage and especially the marrow insides bones. Perhaps boiling it in bleach might be more effective. This would have to be done outside, say on a fire pit or grill, as you don't want your home filled with bleach fumes. Also, avoid using an iron pot, as the bleach would cause it to rust. StuRat (talk) 16:39, 8 March 2011 (UTC)

Sad story: I recently shot an 800 lb boar hog. I couldn't make head cheese from it for boring reasons, so I just put it in the woods for critters to eat the flesh off and I'd have an epic skull with enormous tusks. I screwed an eye hook into the skull and wired it to a tree. When I went back a week later it was gone. The wire had been broken off. :( --Sean 14:45, 8 March 2011 (UTC)

A rotting boar skull covered with maggots and flies sound very Lord of the Flies to me. StuRat (talk) 16:42, 8 March 2011 (UTC)

If only you had the foresight to embed a transmitter with a GPS device in the brains! Comet Tuttle (talk) 18:04, 8 March 2011 (UTC)

Instead of bleach use strong ammonia solution. It will dissolve the fat. Graeme Bartlett (talk) 04:44, 9 March 2011 (UTC)

Pistol shrimp & goby fish

The pistol shrimp often lives in symbiotic life with the goby fish. The pistol shrimp is almost blind, but is able to dig long galleries for their common home; the gobi does nothing, but watchs around with his big eyes, should a predator be approaching, in which case, he gives the alarm and quickly leads the shrimp back home. The shrimp also carries a kind of big and loud gun in one of his claw, that uses to shoot down his preys (the continuous gunshots of these guys even interfere with submarines' sonar system, they says). Apart the obvious side remark that God is apparently an addicted Marvel Comics reader, I wonder: how does the goby avoid being shot by his blind gunslinger friend? Thanks. --pma 22:04, 7 March 2011 (UTC)

I don't have an answer, but this has been sitting here a few hours now and I just have to say: this is the funniest, cutest and quirkiest subject / question I've seen here for a long time. I've probably read past it ten times and it still makes me smile, absolutely love it. :) Vespine (talk) 05:31, 8 March 2011 (UTC)

You mean DC Comics. According to the goby fish article, the symbiotic gobies are known as Watchmen. ;) (Sorry, no real answer yet - though I should say that the shrimp apparently knows how to target its prey) Wnt (talk) 05:47, 8 March 2011 (UTC)

I am shocked to learn that the pistol shrimp is blind, when that other famous slinger of shrimpoluminescence, the mantis shrimp, has the most complex eyes in nature. --Sean 15:18, 8 March 2011 (UTC)

Still no solid responses, so here's my (educated) guess:

• First, all sources I've seen describe the symbioses as being very species-specific, meaning that not just any goby will pair up with any tunnel-building shrimp. Thus, goby species specializing in pistol shrimp pairing probably do have behavioral or morphological ways of avoiding damage.
• One organ system that may be specialized to be resistant to shock is the lateral line. Although other systems are effected as well, this seems to be the most sensitive to shock, so that's the first place I'd look for shock resistance.
• The shockwave produced is directional according to this paper, [8]. So Wnt may be on to something: the shrimp may just keep the cone of damage away from its friend (which is often in actual physical contact with the shrimp, making this easier).

Good question, but there seems to be a dearth of organismal biologists and ecologists here. Let us know if you find out any better answers. SemanticMantis (talk) 17:52, 9 March 2011 (UTC)

Also, I suspect the folks at the fishbase forum might be able to provide more information [9]. SemanticMantis (talk) 15:36, 10 March 2011 (UTC)

doxycycline

What was the antibiotic doxycycline first isolated from? 82.132.248.19 (talk) 23:22, 7 March 2011 (UTC)

Tetracycline_antibiotics#History has some background. While doxycycline is not directly covered, it seems that the tetracyclines in general seem to derive from various strains of Streptomyces bacteria. --Jayron32 23:38, 7 March 2011 (UTC)

Doxycycline is a semi-synthetic antibiotic: it can't be isolated from any organism because it doesn't naturally occur in any. I believe but can't find a reference, that's it's produced by chemically altering the naturally occurring tetracycline (obtained by fermentation with Streptomyces species). You may be interested in the history section of this article- Nunh-huh 03:09, 8 March 2011 (UTC)

FYI ... Having been awake for like 5 minutes, and with virtually zero brain function, I quickly type in the Google search phrase "Invention of Doxycycline" and got the WORST result I've ever SEEN from Google! It was so goofy, I just HAD to post it here. WOW! I think I will now make an attempt to re-boot my brain, and move on to something else. LOL!

Best regards

Cliff L. Knickerbocker, MS (talk) 13:43, 12 March 2011 (UTC)