Wikipedia:Reference desk/Archives/Science/2009 April 5

= April 5 =

Evolution of Wings
Here's a new idea about the evolutionary development of wings:
 * http://www.telegraph.co.uk/scienceandtechnology/science/dinosaurs/5105218/Dinosaurs-may-have-evolved-wings-to-attract-mates.html
 * GlowWorm. —Preceding unsigned comment added by 98.17.33.139 (talk) 08:41, 5 April 2009 (UTC)
 * And? Zain Ebrahim (talk) 11:02, 5 April 2009 (UTC)

There is also the modern-day lizard that runs upright on its two hind legs. As it does that, it holds its front legs sideways, spreading out a large flap of skin between each front leg and its body. I think it does that only when frightened, and the tactic may serve to scare the creature that frightens it. I don't remember the name of the lizard or where it's from, but most people have seen videos of its comical appearance when running like that. Can anyone give a lead to a site giving information about this lizard, including its taxonomic name? – GlowWorm. —Preceding unsigned comment added by 98.17.33.139 (talk) 14:21, 5 April 2009 (UTC)

Further information on biological wings is given in the Wikipedia articles Flying Fish and Flying and Gliding Animals. These articles provide arguments against creationists who refer to wings to support their views. – GlowWorm. —Preceding unsigned comment added by 98.17.33.139 (talk) 14:54, 5 April 2009 (UTC)


 * Are you referring to the frill-necked lizard or one of the dracos? -- k a i n a w &trade; 15:02, 5 April 2009 (UTC)


 * The one I was thinking of runs along the ground but I don't think it glides through the air. Thanks for the reference to the frill-necked lizard and the Draco gliding lizards; I was not aware of those. – GlowWorm —Preceding unsigned comment added by 98.17.33.139 (talk) 15:21, 5 April 2009 (UTC)


 * On second thoughts, it is probably the frill-necked lizard that I am thinking of. It does not fly or glide. The photo of it in Wikipedia was taken from slghtly above it, rather than straight on while running, which is the way a rather well-known video shows it. I think the difference between flying and gliding of any creature is that gliding does not involve rising in the air except on thermals or other updrafts. Also, flying uses muscle-power input to rise. (Although gliding of living creatures may involve muscle-power input to maintain stability and to change direction.) But there is a very fine distinction between flying and gliding. – GlowWorm. —Preceding unsigned comment added by 98.17.33.139 (talk) 15:56, 5 April 2009 (UTC)


 * Yes, it's the frill-necked lizard (Chlamydosaurus kingi) I am thinking of. It does not fly, but its skin flaps could develop into wings. Some videos of this lizard are shown at http://www.youtube.com/watch?v=xWDgQH-2pCo. A couple of the videos show it running. – GlowWorm. —Preceding unsigned comment added by 98.17.33.139 (talk) 16:12, 5 April 2009 (UTC)

Atherosclerosis
Atherosclerosis can be caused by smoking, but a person with Atherosclerosis might not necessarily be a smoker. Am I right? Thanks. —Preceding unsigned comment added by 116.71.32.237 (talk) 09:31, 5 April 2009 (UTC)
 * Yes, read our article. 121.72.192.28 (talk) 10:47, 5 April 2009 (UTC)

Puberty and growth
On average, at what age does puberty stop and at what age does growth and physical developemnt peak. Are there significant physical changes between the ages of 16 and 18, 18 and 21? Clover345 (talk) 12:18, 5 April 2009 (UTC)


 * Did you read our articles on Human development and Puberty? --Jayron32. talk . contribs  12:37, 5 April 2009 (UTC)


 * Yes but they don't really answer my question. Thank you for your efforts however. Clover345 (talk) 13:36, 5 April 2009 (UTC)


 * Girls typically finish growing before boys do (which is how boys usually end up bigger). Girls often reach full adult height before 16, while boys may continue into the 16-18 year old range, and sometimes into the 18-21 year range.  Growth often follows the pattern of "growing up" first, then "filling out".  So, both boys and girls may reach full adult height, but be skinny, then later become more muscular (mainly in the case of boys) and more curvy (mainly in the case of girls, with additional fat deposits on breasts, butt, and hips).  Because of the age delay, girls are likely to have reached their full adult height by 16, but may continue to fill out in the 16-18 year old range (it would be somewhat unusual if this continued into the 18-21 year old range).  Boys may reach full adult height in the 16-18 year old range and continue to fill out in the 18-21 year old range.  Note that ethnic group, diet, exercise, and other factors also have an effect here, as may exposure to hormones in food and medications. StuRat (talk) 15:40, 5 April 2009 (UTC)


 * Don't girls also usually start puberty earlier? Nil Einne (talk) 14:15, 6 April 2009 (UTC)


 * Yes. StuRat (talk) 17:17, 6 April 2009 (UTC)

Foods endemic to the Americas...
I got into an interesting discussion tonight over dinner with a fellow here in China about which foods are endemic to which areas.

With respect to the Americas I know of corn, peanuts, tomatoes, "wild" rice, sunflowers, and peppers. I'm sure there are more, however, and am having trouble finding a scholarly listing.

Can anyone help me out? —Preceding unsigned comment added by 61.189.63.137 (talk) 12:42, 5 April 2009 (UTC)
 * You missed potatoes...there's more obscure things, too, like fiddleheads, eulachon and eulachon grease, camas....I suggest you go looking for "ethnobotany" materials, though many indigenous foods like eulachon and camas are not widespread and were not exported like so many others were; particular animal species, too, I don't think is waht you mean, nor specialty dishes like poutine or Nanaimo bars; i.e. you're looking for plants/vegetables yes? If indigenous foodtsuffs like those and particular wild game and fish species are taken into account, the list is conceivably quite large....as for indigenous cuisines, whether aboriginal or creole or French-Canadian, like poutine, that's even bigger, likewise "generic North American cuisine" like the hamburger....see figgy duff...oh, gee, there's an article needs writing, I'm not qualified to do so however....Skookum1 (talk) 12:57, 5 April 2009 (UTC)

Yeah, I was intending to keep it solely to plants...61.189.63.137 (talk) 12:59, 5 April 2009 (UTC)
 * Cassava is another major one. Cacao is essential for all human life ;-). And corn should probably be specified as maize, as in most non AmE-variants it stands for generic cereals ("corn, such as wheat and maize..."). If you also allow for meat, there is Turkey (bird).--Stephan Schulz (talk) 14:07, 5 April 2009 (UTC)


 * This site has a pretty extensive list. Looie496 (talk) 15:57, 5 April 2009 (UTC)
 * Wikipedia's list is at Indigenous peoples of the Americas. Beans, squash, pumpkins, vanilla, chicle, strawberries, pineapple, tobacco... Rmhermen (talk) 23:19, 5 April 2009 (UTC)
 * In addition To things listed above there are things that weren't farmed, but gathered. Some of these are also found/used in other parts of the world. > Acorns, Beech nuts, Pine nuts, red Huckleberry, Elderberry as well as several leaf vegetables like Goosefoot, Clover, water lettuce (Sources vary on whether this is native or was introduced later) and roots like Arrowroot and Nymphaea (our article only mentions the Egyptians, but Native Americans made flour from them, too) . Plus Quinoa and Sweet potato in South America.  This is very likely still an incomplete list and varied quite a bit by actual location. 76.97.245.5 (talk) 05:46, 6 April 2009 (UTC)

Are these droppings?
Hi. Today I have been cleaning out my shed and I have come across what seem to be some kind of droppings on a couple of boxes and also on the floor. The link below show the droppings and also some damage to some childrens floor tiles (not sure if they have been chewed). I just wondered if anybody could please verify whether these are droppings, and from what animal. Also, if anybody could verify that those tiles have been chewed, and possibly identify what has chewed them.

http://www.flickr.com/photos/37087515@N04/sets/72157616380686806/

Thanks in advance. Lonely Banana (talk) 14:15, 5 April 2009 (UTC)


 * Those look like rodent droppings -- could be rat, mouse, or some other rodent depending on size and situation. Rat droppings are typically about an inch long, mouse droppings much smaller. Looie496 (talk) 15:52, 5 April 2009 (UTC)


 * Thanks. I think that they are too small for rat droppings, so are likely mouse. I am going to throw out all of the boxes and sanitise the shed floor with bleach and hot water. I amy also set some traps. Are there any other precautions I should take? Thanks again. Lonely Banana (talk) 19:35, 5 April 2009 (UTC)


 * You can mouse proof the shed by filling in all the cracks, especially around and under the door. so that they cannot come back in once you have trapped them. Graeme Bartlett (talk) 21:26, 5 April 2009 (UTC)


 * In my (limited, UK) experience, this could be either or both.
 * The chew damage resembles that which I once incurred on the foam-rubber padding of some folding garden chairs I was keeping in an astronomical observatory I then helped to run. This was almost certainly the work of yellow-necked mice (similar to field mice: we later caught one), probably collecting bedding material. Rats more often chew to test potential foodstuff (or to gain access, or merely to trim their ever-growing teeth, neither applicable here), but being more intelligent would probably not have persisted so long with these (presumably non-edible) bricks.


 * The droppings could be either large mice or young rats. I once found similar droppings in my house (next to modestly nibbled, pictorially wrapped plastic-sealed chocolate I'd left out on display) which I initially attributed to mice. Subsequently (after failing with traps, more food being assaulted, and the droppings becoming larger) it turned out to be rats, which I eventually eliminated by persistently supplying them with proprietary-brand poisoned grain. (I had to endure a moderate pong for a few weeks, while presumably a rat corpse or two in the foundations decayed away.)


 * Mouse-proofing a shed would be possible but difficult - they climb, and can get through amazingly small gaps. Rat-sized gaps are easier to fill: I used expansion foam, which can be bought in aerosol cans, injected into a pre-emplaced matrix of steel wool, as recommended to me by a professional pest control operative who serviced my workplace. Realistically, however, rats can gnaw a new entrance through wood any time they feel like it (brick and concrete merely slow them down).


 * Either way, try to remove anything that rodents might consider food or bedding material (cardboard, paper, cloth, etc) from both in and near the shed (don't put foodstuffs in your compost heap if you have one), and try to organize the shed contents so that you can periodically inspect all floor and wall areas for newly-created holes.


 * Since rodents are evidently in the area, think about similar measures for your house, and try to keep rodent-attractive foods inside well-sealed cupboards or stout sealed containers, preferably metal. 87.81.230.195 (talk) 09:37, 6 April 2009 (UTC)

wathurrrrrrrrrrrrrrrrrrrrrrrrrrrrr
Since ice is less dense than water, and a liquid put under enough pressure becomes a solid, what happens to water when it's under enough pressure to turn to ice? Water expands when it freezes, but it can't do that here...


 * To be overly general, water compresses to minimal volume at 4 degrees Celsius. If you want a lot of technical science stuff, just ask. --  k a i n a w &trade; 15:03, 5 April 2009 (UTC)


 * In general if you lower the temperature of a liquid to below its freezing point but it can't become a solid, it is called supercooling. --98.217.14.211 (talk) 15:07, 5 April 2009 (UTC)

That's not what I'm asking though... lemme try again. The solid form of water takes up a greater volume than the liquid form, right? And when a liquid is under great enough pressure it becomes a solid, right? So what happens when water is under great enough pressure to solidify? It can't do it the same way it normally does, right? There's not enough room.


 * I think if you read Triple point, it will answer your question. If not, try Water (molecule). Looie496 (talk) 15:50, 5 April 2009 (UTC)


 * Look at the phase diagram (in some article mentioned by other replies): If you are at standard atmospheric pressure, and a bit below the melting point (273.15 K) then ice will actually melt if the pressure is increased by a few atmospheres. Only at much higher pressures will it solidify again. There is a certain pressure at which the melting point is lowest, see here. -Icek (talk) 16:18, 5 April 2009 (UTC)

The short answer is that the statement "water expands when it freezes" only describes its behavior under normal pressures. (Likewise, the statement "liquid water is incompressible" is only an approximation.) Under high pressure water does not turn into normal ice, but forms other kinds of ice with different crystal structures that do not involve expansion.

These other kinds of ice are identified by Roman numerals, ice II, ice III, and so on up, about 10 or 15 kinds altogether. They are considered distinct phases of water just as ordinary ice and liquid water are distinct phases, and a complete phase diagram of water will show them all. (And now someone will not be able to resist mentioning ice-nine, a phase of water that exists only in fiction, so I'll do it first. Follow the link to read about that.)

--Anonymous, 19:59 UTC, April 5, 2009.

Regurgitation in animals.
I was reading about Orca where it says some captive specimens had learnt to regurgitate fish to attract sea gulls which they could then eat. I was wondering how animals get around all the side effects that characterise Bulimia (hypokalaemia, hyponatraemia, oesophageal damage etc) when they induce vomitting, question can be expanded to birds land mammals that feed their young in this way. MedicRoo (talk) 17:48, 5 April 2009 (UTC)


 * Our Gastric acid article unfortunately doesn't include non-human info. Some animals cough up Hairballs and owls are well known for their pellets.  On the other hand animals can engage in behavior that is ultimately detrimental.  Sea otters have learned to crack oysters on a rock they put on their belly.  However it was found that that will eventually damage their ribcage. 76.97.245.5 (talk) 16:19, 6 April 2009 (UTC)


 * Our articles on vomiting and regurgitation point out there are mechanistic and physiological differences between the two, and that regurgitation and vomiting are not interchangeable terms. Although the regurg article says that some people (including bulimics) are able to train themselves to voluntarily regurgitate, I would expect that the majority of people with eating disorders who purge on a regular basis are in fact inducing vomiting rather than regurgitating, and that is the reason for the frequency of electrolyte abnormalities, oesophageal trauma and dental damage.   Matto  paedia  Have a yarn  02:39, 8 April 2009 (UTC)

Blue water
Time for a question of my own. My family recently had the bathroom redone, and now we have a white tub in the place of our previous blue-colored porcelain one. Since then, I have seen something I've never seen before: our water has a decidedly blue tint to it. We have a well and live near the top of a hill away from any farms, so I doubt its any sort of additive or contamination. My question is this: what sort of mineral/chemical in ground water (or possibly our pipes?) could cause a blue tint in water?- Running On  Brains  19:23, 5 April 2009 (UTC)
 * Well, water is slightly blue. I'd suspect that you've just managed to set up nice conditions to see it.  See color of water. 81.158.123.157 (talk) 19:49, 5 April 2009 (UTC)
 * I suppose that could be part of it, but the areas of the tub where water hits most often (underneath the faucet and near the drain) have a blue stain on them, so that led me to believe it was something in the water (probably should have mentioned this initially).- Running On  Brains  19:57, 5 April 2009 (UTC)
 * You'd need a lot more water than a bath holds to see the blueness of the water. 90.195.179.144 (talk) 21:01, 5 April 2009 (UTC)
 * The blue stain can be due to copper. Slightly acid water can dissolve copper in the pipes.  Particularly if the water was sitting in the pipes unused for a few weeks, it could have built up somewhat.  You can probably remove the stain with ammonia if you can't scrub it off.  In my area the water company adds slaked lime to the water to control the pH.  —Preceding unsigned comment added by 152.91.9.190 (talk) 21:20, 5 April 2009 (UTC)
 * Wouldn't that actually be copper sulfate? I would have thought that copper from pipes would most likely be an oxide, and therefore a bit greenish.  I've seen some rivers and underground lakes at Jenolan caves (in the Blue Mountains, Australia)that were distinctly blue, and I remember being told it was from CuSO4 in the vicinity of the  river's spring.   Matto  paedia  Have a yarn  02:43, 8 April 2009 (UTC)

Light bulb energy
Do light bulbs use up more energy during activiation (er...when you switch them on) than they do during normal running? My mother insists I leave lights on all around the house because "it takes more energy to turn them back on".

Also, this bit's more for curiosity - what does this apply to? I know blast furnaces need to be left on all the time because it takes a lot of energy to re-start them. What abut cars? Computers? My Wii? 90.195.179.144 (talk) 19:38, 5 April 2009 (UTC)


 * Mythbusters actually tackled the bit about the lights. It does take more energy to activate lights than to keep them on BUT this is only about a second or so of light operation's worth.  So it wastes much more energy to leave lights on then to turn them off (episode summary here).  As for your other questions, that's for someone smarter than me :-D - Running  On  Brains  19:53, 5 April 2009 (UTC)
 * Thanks. Err...Don't suppose you'd know how that would translate to these new energy-saving light bulbs that my mother bought, would you? :p 90.195.179.144 (talk) 20:00, 5 April 2009 (UTC)
 * As far as I know, all energy-saving bulbs are either fluorescent or LED lightbulbs adapted for a normal bulb's outlet.- Running On  Brains  20:04, 5 April 2009 (UTC)


 * The common fluorescent lights that first come on dimly, then brightly a second later use more electricity during the dim phase. Incandescent lights use more electricity for a brief fraction of a second while coming to full brightness.  As stated, the amount of electricity is insignificant.  However, the wear and tear on both the switch and the light bulb/tube is another matter.  It makes sense for this reason, as well as for your own convenience, to leave them on rather than switching them off if it will only be for a short time.  --Anonymous, 20:03 UTC, April 5, 2009.


 * Regarding cars, according to CNN :


 * "It's probably a myth that goes back to the days when cars were equipped with carburetors, but many drivers believe that starting up and turning off your car repeatedly is a fast way to drain your gas tank.


 * "But because of modern fuel-injection technology, drivers actually save gas by turning off their engine than letting their car needlessly idle, says Consumer Reports' Paul.


 * "Granted it's probably not sensible shutting down the engine every time you get stuck in traffic, but if it looks like you might be at the drive-thru for more than 30 seconds to a minute, it's worth turning off your car, says Paul." A Quest For Knowledge (talk) 20:39, 5 April 2009 (UTC)


 * The lifetime of a compact fluorescent light, measured in burning hours, is far less if it is switched on and off frequently than if it is left on for several hours each time. CFLs are not recommended for motion detector light applications.The electrical energy would be reduced as for incandescent bulbs, is it is turned off when the light is not needed. Incandescent bulbs are not affected nearly as much in their lifetime burning hours if they are switched on and off frequently. Edison (talk) 03:10, 6 April 2009 (UTC)
 * I think that answers everything I need to know. Thanks. 90.193.232.106 (talk) 18:09, 6 April 2009 (UTC)

Wet hands and light switches
Are they really dangerous, like I was told as a child? 90.195.179.144 (talk) 19:46, 5 April 2009 (UTC)


 * Can they be? Potentially.  If there's enough water present, then yes, you might be able to close a circuit and electrocute yourself on mains voltage.  In general use, however, it's unlikely.  If you've ever gotten a static shock off a light switch, then you're connecting to grounded metal rather than anything hot.  Water on your hands, in usual amounts, isn't likely to connect you to anything more dangerous than that.  That said, there's no good reason to go slinging water at a switch just to say "I told you so!" &mdash; Lomn 22:51, 5 April 2009 (UTC)


 * The usual problem with this kind of thing is that you get away with it most of the time - but if there is a problem in the light switch itself then you are in serious danger. It's definitely not a safe thing to do.  In the UK, light switches that are in bathrooms, etc are mounted on the ceiling with a long pull-cord - this keeps the switch itself high up out of reach of wet hands. SteveBaker (talk) 03:22, 6 April 2009 (UTC)


 * Note that in bathrooms you are also likely to have wet feet, which increases the hazard if you do touch something electrically live with your hands -- what you especially don't want is for current to enter your body through your hand and exit to ground through your foot (or your other hand), passing through your heart on the way.


 * If there's something that almost all the time doesn't hurt you at all, but 1/1,000 of the time it kills you, is it correct to call it "really dangerous"? What if it was 1/100 or 1/10,000 or 1/100,000 instead of 1/10,000?  Would you call it "really dangerous" then?  Because this is the way that electric shocks from the household power supply are. There's not enough current to cause tissue damage by burning, the way you could get from lightning or a high-voltage line; if you get an unpleasant jolt, you let go and you're fine. But if the current hits your body the wrong way (and, perhaps, at the wrong time in your heartbeat cycle), your heart stops and you drop dead.  I am not saying that 1/100 or 1/1,000 or 1/10,000 or 1/100,000 is the correct number there; I wasn't able to find statistics on that.  But I am saying that it's not really clear how to answer the question.  --Anonymous, edited 03:41 UTC, April 6, 2009.

swelling AROUND the eyes and diabetes
Hi Wikipedians:

I'm wondering if swelling AROUND the eyes (as in periorbital swelling/puffy eyes, like a blackeye without the blackness) have anything to do with type 2 diabetes.

I've looked over all the eye related complications of type 2 diabetes on the American Diabetes Association website, none of the conditions listed there seem to indicate swelling around the eyes.

This is just out of scientific curiosity and is not related to any medical issues.

Thanks.

65.95.97.197 (talk) 19:59, 5 April 2009 (UTC)


 * Oops, never mind, stupid me, it's an indication of Diabetic nephropathy. 65.95.97.197 (talk) 20:05, 5 April 2009 (UTC)

'Physalis Mottle Virus’
hey all, What are the implications of 'Physalis Mottle Virus’ on water quality and human health?? Is it dangerous?? what does its presence imply for potable water consumption....? Thanks.

CAnnB (talk) 23:07, 5 April 2009 (UTC)


 * Hi CAnnB. PhMV (Physalis Mottle Virus) is a Tymovirus, a plant virus. AFAIK, it has no effect on any animal, humans included. --Dr Dima (talk) 04:16, 6 April 2009 (UTC)
 * As for your last question - what you should really worry about is what else is in that water, and how it became contaminated. --Dr Dima (talk) 04:27, 6 April 2009 (UTC)