Wikipedia:Reference desk/Archives/Science/2009 April 14

= April 14 =

DNA
Can one do a DNA test from vomit? —Preceding unsigned comment added by 12.216.168.198 (talk) 00:21, 14 April 2009 (UTC)


 * Sure, though not necessarily all instances of vomit. The vomit itself -- that is to say, that charming combination of stomach acid, half-digested food and whatnot -- probably doesn't contain any, but it's not uncommon for the vomit to have bits of stomach lining in it, for example. Likewise, people generally do a lot of spitting in the process. (That said, Nigel Tufnel famously opined that you can't dust for vomit, but I grant that he may not be the greatest authority on this subject. Or any subject.) -- Captain Disdain (talk) 01:57, 14 April 2009 (UTC)


 * I bet he knows a thing or two about the glutæus maximus, particularly large ones. ;) Rockpock  e  t  02:15, 14 April 2009 (UTC)


 * Vomit may represent the worst sort of specimen for DNA testing, because a large proportion of the DNA in it may represent a source (food) other than the person you mean to be testing. Ideally, of course, if you can ensure your testing only detects human DNA then you'll only be confused if you're testing a cannibal. --Scray (talk) 02:35, 14 April 2009 (UTC)

stars outside the boundaries of their constellation
is there a name for a star that is named as being a member of one constellation, but actually exists inside the boundaries of another? does such a thing even exist? i had a dream that a star like that was called a "tapuo" or something, so now i'm curious if it actually exists. 99.245.16.164 (talk) 00:35, 14 April 2009 (UTC)


 * I have a copy of A Field Guide to the Stars and Planets, one of the books mentioned in the constellation article. I'm pretty sure that its maps don't show any such thing as a star named as part of a different constellation.  --Anonymous, 00:53 UTC, April 14, 2009.


 * The star Sirrah might be considered an example of what OP refers to: It forms the north-eastern corner of the big square that visually defines the constellation Pegasus (constellation), and historically, it was called δ Pegasi. According to the modern definition of the constellations it belongs to Andromeda, and is even known as α Andromedae. Another example might be β Tauri/γ Aurigae. --Wrongfilter (talk) 07:54, 14 April 2009 (UTC)


 * Bayer designation (whose language I tweaked yesterday) mentions some examples. —Tamfang (talk) 06:34, 15 April 2009 (UTC)

Are diamonds ionic compounds?
Diamonds have some properties of ionic compunds (they are hard, have high melting and boiling points and can conduct electricity) but other properties (such as diamonds not being able to dissolve in water and not being brittle) are not properties of ionic compounds. —Preceding unsigned comment added by 174.6.144.211 (talk) 01:52, 14 April 2009 (UTC)


 * No, the carbon-carbon bonds inside a diamond are covalent bonds. Dauto (talk) 02:09, 14 April 2009 (UTC)

But if diamonds are covalent compoounds then why are they hard, have high melting and boiling points are able to conduct electricity? —Preceding unsigned comment added by 174.6.144.211 (talk) 02:18, 14 April 2009 (UTC)


 * Usually covalent compounds will have covalent bonds (which are very strong) within a molecule but those molecules will bind to each other by week Van der Waals atraction. I diamond has strong covalent bonds all over the whole crystaline structure. In simple terms, it is one single macroscopic molecule. Dauto (talk) 03:11, 14 April 2009 (UTC)


 * Look up diamond. most diamonds are insulators and they more burn rather than melt. The reason they are so hard is how well they electronic/bonding structure matches their packing crystal lattice. Diamonds also have a lot in common with ionic materials.  Diamond aren't so much a molecule or polymer as a material made of repeating unit cells like a ionic solids.--OMCV (talk) 02:24, 14 April 2009 (UTC)


 * I'm stunned to note that we don't have an article on network solids. I'm too swamped to write one at the moment, but if someone wants to dive in, please do! TenOfAllTrades(talk) 12:34, 14 April 2009 (UTC)

More generally, lots of things you learn in school are general guidelines or observed trends, not the actual reasons. "Ionic has property X, non-ionic has property not-X" is only true if being ionic is the exact and only cause of property X. But that's not true for this case: the actual cause of "high-melting" isn't "ionic", but rather it's related to how the molecules are held together. Ionic molecules are merely a common type that are held together in a way to give high-mp. For that reason, "ionic gives high mp" doesn't mean you can say "therefore non-ionic will not be high mp": being ionic is not the only type of molecule that is held together in this certain way. Same goes for any property and any characteristic: need to see how/why the trend works, not use the observed trend as the actual cause and black'n'white separation (correlation vs causation). DMacks (talk) 14:18, 14 April 2009 (UTC)


 * To expand a little bit, the binary "covalent vs. ionic compounds" thing they teach you in basic high school chemistry is a bit oversimplified, and it does not apply to many substances including diamonds. Reorganize your thinking this way.  Compounds either exist as a collection of discrete molecules or they exist as a network of roughly equally bonded particles.
 * Molecules are the "special case" for us to consider. In the case of molecular substances, you have a small number of atoms which are strongly tied to each other, making a tiny packet which itself is electrically neutral; meaning it does NOT much attracted to other substances, and only subject to smallish forces like dispersion forces and dipole interactions.  Therefore molecular substances (calling them "covalent" compounds is misleading, see explanation below) will tend to have low melting and boiling points, be mostly gasseous or low boiling liquids, etc. etc.  The bonding inside of the molecule is covalent bonding, but the bonding between the molecules are relatively weak, and THAT is what makes molecular substances behave like they do.
 * All other compounds consist of billions of atoms all bonded to each other in a highly stable crystal. The strength of these bonds is comparible to the strength of the internal bonds in a molecule, thus ripping apart a salt crystal or a diamond is roughly on the order of physically pulling the hydrogen atoms off of a water molecule; it requires huge forces, which is why "non-molecular substances" are universally strong, hard, and have high boiling and melting points.  Now, these non-molecular substances can be further classified according to the type of bonding holding their atoms together, but these distinctions are not as large as one might imagine.  The type of bonding in non-molecular substances falls into three types: covalent bonding, ionic bonding, and metallic bonding.




 * For covalent and ionic bonding, look at the crappy MS Paint diagrams I uploaded. The both consist of the force of attraction between a positive atomic center and an negatively charged electron cloud.  It's only the location of that cloud (either between the atoms or around one of them) that determines the difference between the two.  Since BOTH consist of the same maginitude of electrostatic attractions, BOTH are going to be on the same order of strength.  Thus so-called "network covalent" solids, like diamond and zinc blende are about as strong as so-called "ionic" solids like sodium chloride and potassium nitrate.
 * For metallic bonding, the electron cloud, instead of being localized either between or around some of the atoms, is instead shared roughly equally between all atoms, creating a so-called "sea of electrons" which explains metals electrical conductive properties. The material is hard because ALL of the electrons in bulk are holding the whole mess together, but the individual electrons are not tied to any individual nucleii, so they are free to move around easily given a little "push".
 * I hope that clears things up a bit for you. So, you see that diamond is infact a covalently bonded substance, but it is not a molecular substance, which is why it does not behave like a molecular substance. --Jayron32. talk . contribs  01:24, 15 April 2009 (UTC)

Atropine as anaesthesia pre-med
Atropine is historically used as an anaesthetic, and apparently is used as a premedication for general anaesthesia today, I can see why you would want to have a lower heart rate, bronchodilation and the like, but as atropine is a CNS stimulant, my question is, why would you use it as an pre-anaesthesia. I know hyoscine would be a better choice. MedicRoo (talk) 11:14, 14 April 2009 (UTC)
 * You may find your answer to why hyoscine (scopolamine) has limited usage compared to atropine at Muscarinic_antagonist, which states that scopolamine crosses the blood-brain barrier, whereas atropine does not. Therefore, scopolamine can cause increased CNS effects such as amnesia, which can in some cases be beneficial, but not all. Also, atropine given intramuscularly initially results in bradycardia. — Cyclonenim | Chat 11:43, 14 April 2009 (UTC)
 * Slightly irrelevant to the OP's question, but are you sure atropine doesn't cross the BBB? In Atropine it states "hallucinations" and presumably the typical delerium-like effects of anticholinergics. Looking at the chemical structure, it seems fairly non-polar. --Mark PEA (talk) 19:54, 14 April 2009 (UTC)
 * I understand most of the effects and differences, more I'm not clear on why atropine would be used for anaesthesia when it causes CNS excitation instead of depression.MedicRoo (talk) 13:15, 14 April 2009 (UTC)
 * I'm not too sure, all I know is that there is a weak agonist effect in low doses of atropine, which lowers the heart rate. Presumably, this agonist effect spreads throughout the entire parasympathetic nervous system, not just the heart. — Cyclonenim | Chat 13:42, 14 April 2009 (UTC)

The main reasons for using anticholinergic drugs as pre-medication are:-


 * 1) Drying of secretions
 * 2) Prevent bradycardia
 * 3) Anti-emetic
 * 4) Prevent laryngospasm

Other possible benefits are relatively unimportant. The sedative effect of hyoscine is not usually regarded as beneficial when giving general anaesthesia. Indeed the sedative effect of hyoscine may be tricky to predict, especially in the elderly. Other anaesthetic drugs give a more reliable response. Axl ¤  [Talk]  17:34, 14 April 2009 (UTC)
 * Bugger, somewhere along the line me and atropine went seperate ways and I thought it was right behind me. Thanks for the help.MedicRoo (talk) 18:05, 14 April 2009 (UTC)
 * I know that atropine is frequently used when doing surgery on rats, because it dries them out and makes it less likely that they will choke on their saliva. It isn't an anesthetic as far as I know. Looie496 (talk) 01:35, 15 April 2009 (UTC)

Separating Water(H2O) and Hydrogen Peroxide(H2O2)
The hydrogen Peroxide(H2O2) you buy at pharmacies are so low concentrated and are dissolved in water(H2O), and I want more pure hydrogen Peroxide, but don't want to use so much money to buy the expensive high concentration hydrogen Peroxide(H2O2) from large companies.Can I remove the water by evaporation(H2O2's boiling point is 150.2 °C but water's boiling point is 100 °C)? Please tell me other methods too! The Successor of Physics  15:19, 14 April 2009 (UTC)


 * Have you read our excellent article on hydrogen peroxide ? Especially the part that says "Above roughly 70% concentrations, hydrogen peroxide can give off vapor that can detonate above 70 °C (158 °F) at normal atmospheric pressure. This can then cause a boiling liquid expanding vapor explosion (BLEVE) of the remaining liquid. Distillation of hydrogen peroxide at normal pressures is thus highly dangerous ." Maybe there's a good reason it's only generally available in low concentrations .... Gandalf61 (talk) 16:42, 14 April 2009 (UTC)


 * Makes pretty good rocket fuel though. The higher cost of high purity H2O2 would be because it is difficult to make safely. 65.121.141.34 (talk) 18:10, 14 April 2009 (UTC)


 * The main reason it's only available at low concentrations is because high concentrations are very dangerous. It looks exactly like water, but if you take a swig of highly concentrated H2O2 and swallow it before you know what you're doing, say goodbye. Looie496 (talk) 01:38, 15 April 2009 (UTC)
 * I know what Looie496 and 65.121.141.34 said but forgot what Gandalf61 said! Well if I can't seperate them by evaporation, then how about cooling(I'm not even sure is there such a separation method)(H2O2's melting point is -0.41 °C but water's melting point is 0 °C)? The Successor of Physics  13:05, 15 April 2009 (UTC)

H2O2 has a density about 40% greater then water, perhaps a centrifuge could separate them? 65.121.141.34 (talk) 15:39, 15 April 2009 (UTC)


 * You can't use evaporation to concentrate hydrogen peroxide above the point where it becomes an azeotrope. Does anyone here know what that point is? — DanielLC 16:31, 15 April 2009 (UTC)


 * I know this is a very old thread, but in response to DanielLC, H2O2 and water do not form an azeotrope. Complete (to all intents and purposes) separation is possible with a sufficiently tall distillation column. Preferable vacuum distillation so you don't blow everything up.

4th Dimension...again
http://www.math.union.edu/~dpvc/math/4D/projections/welcome.html

According to this link, what would we look like to a entity that can see in 4D? --Reticuli88 (talk) 15:36, 14 April 2009 (UTC)
 * Well, we would look like ... a 3D entity. Equendil Talk 17:08, 14 April 2009 (UTC)

Ok. What would we look like as a 4D entity? --Reticuli88 (talk) 18:45, 14 April 2009 (UTC)


 * If we were (somehow) a 3D object in a 4D world, we'd look kinda "flat" - much like a drawing on a 2D sheet of paper looks to us in the 3D world. But this is basically a silly question.   If the universe had 4 spatial dimensions (and not "curled up" dimensions as string theory supposes) then we would be 4D entities with perceptual systems to match.  With 4D brains, we'd have evolved to be entirely different creatures than we really are...in all likelyhood, there is some deep, dark, physics-ish reason why things like people, DNA, planets, stars and galaxies might simply not be able to exist in a 4D world.  Certainly, such things are impossible in a 2D world.  So this "what would it be like if..." trail our OP is on is entirely fruitless.  All we can say (and even then, not entirely uncontroversially) is what a 4D world might look like to us...as we are right now with our 2D eyes...assuming that the phenomenon of light is possible in a 4D universe, assuming we don't explode into fundamental particles the moment we pop into existence in the 4D world, etc, etc. SteveBaker (talk) 19:41, 14 April 2009 (UTC)

The reason I brought this up was because of the link below:


 * http://sprott.physics.wisc.edu/pickover/fourth.html

The author describes what a 4D entity would appear to us: "....resemble flesh-colored balloons constantly changing in size." Also, as scene in the movie Contact, Jodie Foster's character experiences a sort of 4D experience, I think. I mean the scene when she exclaims "They're alive!" the first time; the scene where it appears she splits in two. Does anyone know this reference? I'm just trying to get some handle what 4D would appear to us lowly humans. --Reticuli88 (talk) 20:40, 14 April 2009 (UTC)


 * You might like to read Flatland; it's a good way to start thinking about these things. It uses a common approach to these things; what would 3D objects look like to 2D entities? Then extrapolate. For example, (and this is probably something like what the author of that link is getting at) a 2D entity experiencing a 3D entity would itself really be a 3D entity which only experienced 2 dimensions (like an ant that never looks up or down). If a sphere passed through the 2D entity's plane, the 2D entity would experience it as a circle which got bigger and bigger, then smaller and smaller. Equally, a 4D hypersphere passing through our 3D space would appear as a 3D sphere that got bigger and bigger, then smaller and smaller. More complicated shapes would change in more complicated ways.
 * The entity would only appear as flesh-coloured balloons if they were flesh-coloured (whose flesh?) and bulbous. 217.43.141.59 (talk) 21:52, 14 April 2009 (UTC)


 * I don't understand why people keep recommending Flatland - I can't believe that anyone who has actually read the book would ever wish it on anyone else! It's a simply awful book!  It's turgid, sexist, racist, class-ist and everything-else-ist.  It's really painful to read.  It tells you nothing meaningful about different numbers of dimensions and the author is clearly quite confused about his explanations of the 2D world (his description of houses is particularly ill-thought-out.  So - forget that piece of junk and read Planiverse by A.K. Dewdney - this is an entirely self-consistent world in two dimensions - it has plot, it has amazing diagrams of 2D gadgets (if you have any interest in mechanical gadgets, you'll spend ages staring at the wonderful 2D steam engine - and thinking SURELY there is a way to have 2D wheels that work usefully (there isn't)...the 2D house and 2D space-station are also pretty interesting) - and it has a comprehensive appendix that explains in detail the problems with there being an actual 2D universe.  It's written by a mathematician so you can be reasonably sure that it's properly thought through.  It remains one of very few works of fiction that survives on my "top 20 books" bookshelf!  Read it!  NOW!!!! SteveBaker (talk) 22:42, 14 April 2009 (UTC)
 * Brilliant! Here's a link to the steam engine diagram for anyone who can't find it themselves.  Sp in ni ng  Spark  00:14, 15 April 2009 (UTC) although lighting a fire strikes me as a bad idea on a world that only exists on paper  Sp in ni  ng  Spark  00:24, 15 April 2009 (UTC)
 * One aspect of the steam engine diagram that may not be evident without reading the book is the question of how 2D beings could assemble such a machine? When you look at it at first sight, it seems impossible.  However, what you may not appreciate is that the parts that look like the artist shaded them with a bunch of thin parallel lines - actually represent a glued laminated material that the people of the 2D world have developed to solve this exact problem.  By building up the steam engine from layers of thin material, glued together, they are able to fabricate the machine perfectly well.  When you understand THAT - you've gotta go back and stare at the diagram for ANOTHER 10 minutes to convince yourself that's really true.  I just flipped through the book again - the stuff about the 2D computer is really quite clever...how do you make a computer when wires can't cross each other without shorting out?   Also how does a 2D being eat and excrete without falling in half?  All of these things are quite nicely explained.  Like I said - it's an amazingly well put-together book. SteveBaker (talk) 22:40, 15 April 2009 (UTC)


 * Flatland is a satire. You're not supposed to like the sexist and classist society it describes. As a satire I think it's pretty clever. But I don't understand either why people keep recommending it as a book about life in two dimensions. Abbott obviously didn't much care about that side of the story. There's nothing in the book about two-dimensional physics or biology, and what little it says about geometry could fit on one page. For that you have to slog through 150 pages of the narrator complaining about the baseness of women and the isosceles class. Think of it as part five of Gulliver's Travels, though, and it's a good read. -- BenRG (talk) 12:55, 15 April 2009 (UTC)
 * Yeah - I've heard it described as a satire - but it doesn't seem in any way to be poking fun at these ideas. If you told me it was a stinging diatribe about the fickle nature of women and the uselessness of the working classes - I'd have been more inclined to believe it.  SteveBaker (talk) 17:57, 15 April 2009 (UTC)
 * Well, consider that as the dimensionality decreases, so does one's respect for the inhabitants. The King of Lineland isn't much when compared to A Square, and the sole inhabitant of Pointland is a horrid egomaniac. By analogy then, the implication is that the figures in Flatland are not only physically, but morally, inferior to we Spacelanders. And, BTW, the Sphere, itself, is a bit on the pompous side. (Perhaps the Hyperspacers have higher ethics.) B00P (talk) 23:10, 15 April 2009 (UTC)

In this 4D world our 3D world would appear like the stiff flat cross section showing at 1:48 to 2:04. Cuddlyable3 (talk) 00:08, 17 April 2009 (UTC)

orion
A friend of mine told me that you can see the constellation Orion in Australia, but that it looks upsidedown then what is normal in the northern hemisphere. Was he just joking with me, or is there truth to this? 65.121.141.34 (talk) 16:12, 14 April 2009 (UTC)


 * He is not joking. Dauto (talk) 16:23, 14 April 2009 (UTC)


 * You can currently catch Orion for about three hours after sunset, looking westwards, tilted about 90° clockwise compared to the northern hemisphere (with Sirius above) after which it disappears below the horizon to reappear later during the day lost in the sun glare (and "upside down" for a while). Equendil Talk 17:03, 14 April 2009 (UTC)
 * It's true - from the point of view of someone looking at Earth from the outside, someone in the Southern hemisphere is "standing on their head" relative to someone in the Northern hemisphere. That means that, from their perspective, anything outside the Earth is upside-down compared to what someone in the North sees. --Tango (talk) 18:24, 14 April 2009 (UTC)


 * Obviously, all of the constellations, the sun, the moon and the planets are "upside down" - but not many of the constellations are visible from both the far northern and southern hemispheres...but I guess Orion is one of them.  The MUCH more noticeable thing for me is that the moon is "upside down".  A new moon in the northern hemisphere looks like ')' but in the southern hemisphere it looks like '('.  On the equator, it is an upward curving arc.  I was born and lived most of my life in the UK - which is pretty far north.  A waning moon looks like '(' - and I'd read many times that some cultures believed the waning moon was a boat that carried the gods around (or some such twaddle).   I could never understand why they thought that...until I moved to Texas where the waning moon is rolled over at 45 degrees...and on the equator...it looks just like a boat (well, a canoe, perhaps).   Even now - after living 16 years in Texas - the moon always looks "wrong" to me. SteveBaker (talk) 19:22, 14 April 2009 (UTC)
 * I recall looking at the full moon in New Zealand and trying to figure what was wrong with it. Not sure why but I was totally unable to recognize the "patterns" on the surface at all (I wasn't aware that it was simply upside-down at the time), as if it had been randomized and now I was forced to find another character or face to associate it with. 124.154.253.25 (talk) 03:43, 15 April 2009 (UTC)
 * A new moon looks like a ' ' Are you thinking of a waxing crescent? — DanielLC 16:23, 15 April 2009 (UTC)


 * Orion's head and feet are at 10 degrees north and 10 degrees south respectively, so he's partly visible everywhere on Earth and fully visible (not counting some dim stars) within 80 degrees of the equator. —Tamfang (talk) 06:32, 15 April 2009 (UTC)

Note that it's not as simple as "right-side-up or upside-down". Even at the same location, the same constellation will be seen in different orientations at different times of day when it is in different parts of the sky. Similarly, it is not true that "down" is exactly the opposite direction for people in different hemispheres unless they happen to be in antipodal locations. I'm in Toronto; compared to someone in Buenos Aires I'm not upside-down, I'm sideways.

For a simple example that doesn't require you to wait for nightfall, look at the moon at different times on the same day. The center of the lighted side always points toward the sun -- therefore it points above the horizon when the sun is up, but below the horizon when the sun is down. But the same features on the moon's face are visible, so you can see it's a different way up with respect to you. Well, for someone in a different part of the Earth it's different again. --Anonymous, expanded 04:55 UTC, April 15, 2009.

Muscle pain associated with infection
What is the cause of muscle pain associated with the flu or other infections? I looked at myalgia - no help there. -71.239.110.144 (talk) 18:38, 14 April 2009 (UTC)
 * How about the Causes section of Fibromyalgia? If that isn't any help, asking a doctor should be your next step. Livewireo (talk) 18:54, 14 April 2009 (UTC)


 * The OP is thinking of the pain which is shown as part of sickness behavior. I have little knowledge of the subject, but a quick read on the fever article states "A trigger of the fever, called a pyrogen, causes a release of prostaglandin E2 (PGE2)". A quote from Eicosanoid states: "Pain — The cytokines increase COX-2 activity. This elevates levels of PGE2, sensitizing pain neurons". Ibuprofen is a COX-2 inhibitor and thus should treat this pain. --Mark PEA (talk) 22:40, 14 April 2009 (UTC)

Dilution
Hello. A stock solution of HCl(aq) has a density of 1.19 g/mL and a percentage purity of 39.1%. A lab requires 7.25 L of 0.500 mol/L solution. What volume of stock solution do I need before dilution? I divided the amount of hydrochloric acid needed (3.625 mol) by [HCl(aq)]39.1% (12.76165661 mol/L), reaching the conclusion of 284 mL. The answer key says 303 mL. This is not homework counting for marks. Otherwise, my teacher would not have given me the answers. Did I do something wrong? Thanks in advance. --Mayfare (talk) 20:58, 14 April 2009 (UTC)


 * I'm getting 284 mL as well. Perhaps we're both making the same obvious error (anyone?), or perhaps there's a typo in the book.  TenOfAllTrades(talk) 21:26, 14 April 2009 (UTC)


 * If there is an obvious mistake out there, you can count on me to make it, I get the same answer as Mayfare also (well 284.7 to be exact). The book answer requires a molecular weight of 38.8.  The value I am using is 36.45.  Sp in ni  ng  Spark  22:18, 14 April 2009 (UTC)


 * One thing to double check is what is meant by "39.1% purity" - is it w/w, w/v, v/v, v/w, mol/mol (mole percent) or something else? I would usually expect it to be w/w in this context, but you never can tell. I tried to run the calculation several other ways but none gave me 303 mL, though. -- 128.104.112.117 (talk) 23:14, 14 April 2009 (UTC)

burning of stone
can stones get fire as wood (at any temprature)i.e as wood cause to increase fire ,can stones do same thing —Preceding unsigned comment added by True path finder (talk • contribs) 22:01, 14 April 2009 (UTC)


 * No. In order to catch fire, the object has to be able to combine with oxygen and give off energy.  Wood has energy to give off - and the carbon in the wood can combine with the oxygen in the air to make carbon dioxide.  Rocks have no spare energy to give away - the chemicals they contain don't easily combine with oxygen - so with rare exceptions (Coal, for example), rocks don't catch fire. SteveBaker (talk) 22:27, 14 April 2009 (UTC)


 * Does something that burns (rapidly oxidizes) always have to be exothermic ? I've noticed that aluminum foil seems to "burn" in a hot enough flame, yet doesn't appear to give off energy, since the flame is not self-sustaining (if you try this experiment, please do it outside with a torch, as aluminum fumes can be toxic).  As for the rocks, the two alternatives would seem to be melting and burning.  So, do all other rocks melt at high temps (or perhaps some sublimate) ? StuRat (talk) 15:25, 15 April 2009 (UTC)


 * Aluminum can give off huge amounts of heat when it burns. See thermite. Perhaps it doesn't have enough oxygen when you do it that way? — DanielLC 16:14, 15 April 2009 (UTC)


 * I guess it doesn't have to be exothermic - but for the fire to be self-sustaining, it would. SteveBaker (talk) 17:51, 15 April 2009 (UTC)

Effects of fasting
what r the permanet, bad r good effects of Muslim Fasting (which means without water and any otherthing else for average 12 houres ) —Preceding unsigned comment added by True path finder (talk • contribs) 22:06, 14 April 2009 (UTC)
 * I would start at fasting. Sifaka   talk  22:17, 14 April 2009 (UTC)
 * It will definitely depend on what is eaten before the fasting starts. The obvious possible negative effects would be dehydration, hypoglycaemia and possibly electrolyte imbalance. See: Fasting for a list of some benefits of fasting. Also, the ramadan article states that "Fasting is meant to teach the person patience, sacrifice and humility", so that could be a good effect of fasting, although whether it will teach those things is quite hard to test. --Mark PEA (talk) 22:22, 14 April 2009 (UTC)
 * editing Wikipedia tests all three of those.  Sp in ni ng  Spark  22:31, 14 April 2009 (UTC)

Paradox
How would someone be able to eat their whole own self? Since eating one's whole self requires eating their mouth, how would they be able to eat afterwards? And since it requires eating their digestive system, how would they be digested? 58.165.25.29 (talk) 23:26, 14 April 2009 (UTC)


 * It's not a paradox - it's impossible! Duh!  SteveBaker (talk) 23:36, 14 April 2009 (UTC)
 * Step 1: Create clone. Step 2: Buy fava beans and a nice chianti. Step 3: Eat clone (maybe with ice cream). Clarityfiend (talk) 23:52, 14 April 2009 (UTC)


 * No, fava beans and a nice chianti are only for the liver, not for the whole thing. Still, your approach is perfectly valid. I suggest a simpler, alternative approach. Step 1: spew generous amount of digestive juices. Step 2: digest self. Or, a slightly fancier alternative approach. Step 1: make a cocoon. Step 2: undergo histolysis. Step 3: remember that you are not a butterfly, stop. Step 4: Have a nice day :) . --Dr Dima (talk) 00:46, 15 April 2009 (UTC)


 * If you attempt to eat yourself, by all means do it with relish, however defined. Edison (talk) 04:45, 15 April 2009 (UTC)
 * This reminds me of Ouroboros.-- Lenticel ( talk ) 07:51, 15 April 2009 (UTC)
 * Most human cells are not particularly long-lived, so if you were to consume all of your waste products, hair, nail trimmings, and sloughed skin cells, you will have eventually eaten most of yourself, in a manner. --Sean 16:36, 15 April 2009 (UTC)


 * Put on your will that your body be sent back in time to the present, then, assuming time travel exists and people are willing to fulfill your will, you can eat it. — DanielLC —Preceding undated comment added 01:22, 16 April 2009 (UTC).

Mailbox Key question.
In the neighbourhood where I live, all of the houses share a single mail pick-up point - it's like an apartment complex - there are no mailboxes outside each house. Instead, over by the park, there are rows of tiny locked mailboxes - one for each house - for which you have a key. There is also a row of much larger mailboxes for packages and such. When you get a large parcel, the mailman puts it into one of the large boxes, locks it and places the key into your individual mailbox. Now - here's the thing. The large mailboxes are set up so that you put the key into the lock - turn it to get your package out - but the key won't turn back again - and it won't come out of the keyhole so nobody can steal it. There is a second keyhole that the postman puts a special key into that releases the first key.

I've been trying to figure out how this fiendish mechanism works - the mailbox key looks like a perfectly ordinary key. It's obviously a ratchet or something - but curiosity demands that I know how it ACTUALLY works. Does anyone know of a diagram or something?

SteveBaker (talk) 23:46, 14 April 2009 (UTC)


 * This seems to be the patent of the mechanism in question, but after briefly skimming it, I'm no wiser about how the capture of the key is actually accomplished. Maybe I missed it, or maybe they just don't specify because it was a trade secret. APL (talk) 01:40, 15 April 2009 (UTC)


 * Oh, Here we go. I forgot to check the references. Here's the patent of the keylock. APL (talk) 02:15, 15 April 2009 (UTC)
 * Awesome. Figures 13 though 15 of the patent explain it quite well.  My curiosity is now satisfied.  Many thanks! SteveBaker (talk) 20:52, 15 April 2009 (UTC)


 * I also recall seeing that same mechanism in lockers in bus/train depots and airports. You would pay a quarter and get to use the locker/key once.  Of course, as a result of recent terrorism, such bomb-friendly lockers have probably disappeared. StuRat (talk) 15:17, 15 April 2009 (UTC)