Wikipedia:Reference desk/Archives/Science/2007 November 4

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November 4

Cognitive and socio-cognitive developmental psychology

What's the difference between the socio-cognitive and cognitive theories? Is there any difference? I need to define them for an assignment due soon but I can't distinguish between the two. Thanks in advance. —Preceding unsigned comment added by Psycho marshmallow (talk • contribs) 01:46, 4 November 2007 (UTC)

Direct homework help is a bit verboten, but let me give you a hint: think about the different names. You know what cognitive theory is, presumably. What happens to cognition in extreme cases of social interaction, i.e., if I locked you in a cage since you were born and never talked to you? Can a cognitive theory really stand alone? SamuelRiv 04:12, 4 November 2007 (UTC)

DNA related question

Would the number of units of DNA during the G2 phase be equal to the number of units of DNA in one of the daughter cells? For example, if 100 units of DNA were counted during the G2 phase, would there be 100 units of DNA in one of the daughter cells? —Preceding unsigned comment added by 199.247.235.10 (talk) 05:07, 4 November 2007 (UTC)

This sounds like a homework question, which we prefer not to answer (we even have a guideline that you shouldn't ask it!). Recall that the purpose of DNA replication in mitosis is to ensure that daughter cells each wind up with the same number of chromosomes as the parent cell, so you just have to remember when that replication occurs, and what form the DNA takes in each phase. Read mitosis if you need to brush up, and come back if something is confusing you. Someguy1221 05:20, 4 November 2007 (UTC)

Europa

Though there are historical hallmarks of running water on Mars and seas of liquid methane on Titan; is Europa, with its ocean of salty water underneath a frozen exterior, the best bet for proving the existence of extraterrestial life (past or present)? —Preceding unsigned comment added by Sappysap (talk • contribs) 05:49, 4 November 2007 (UTC)

Please do not count those onboard the International Space Station as extraterrestial life. If the world had to invest in a single mission to find life on a planet, moon, dwarf planet, comet, asteroid or planetary ring in our solar system, what would be the best bet? —Preceding unsigned comment added by Sappysap (talk • contribs) 06:43, 4 November 2007 (UTC)

Gliese 581 c? --Ouro (blah blah) 08:12, 4 November 2007 (UTC)

Well, apart from Europa probably. --Ouro (blah blah) 08:18, 4 November 2007 (UTC)

Europa is a possibility for life. The problem with it is that it's rather far from the Sun and doesn't get much energy from it. The oceans (which many experts dispute even exist) would be exceedingly deep under the ice - so not much light would filter down there, and there is unlikely to be much dissolved oxygen in the water as there is here on earth. Such energy as life would get would have to be from hypothetical underwater volcanos caused by tidal forces of Jupiter continually kneading the moon's interior - and since those would appear and disappear sporadically, it's not clear that life would have time to evolve - and then to survive in open water long enough to find the next volcano when the one they were living next to fizzled out. Having said that, the odds of finding life on Europa are probably better than anywhere else beyond Earth. However, there are other possibilities: Enceladus and Titan both orbit Saturn and have similar prospects for life to have evolved. Of those, Titan actually looks rather promising because it's atmosphere is dense and stuffed full of hydrocarbons. Not enough is known about Enceladus - except that it has water ice deposits. Gliese 581 c is a long-shot. We just don't know much about it. SteveBaker 16:23, 4 November 2007 (UTC)

Oh, I forgot Titan! As for Gliese 581 c, well, if we'd have the resources to develop and undertake a trip there, then we'd probably also have the resources to seek out signs of life anywhere else. --Ouro (blah blah) 16:31, 4 November 2007 (UTC)

Pyramidal neurons and the extrapyramidal system

A digram showing the position of bilaterally symmetric "pyramids" (corticospinal axon tracts) along the side of the Medulla oblongata.

According to this source the neurons contributing to the pyramidal tract are themselves pyramidal neurons, but most pyramidal neurons send axons elsewhere.
Does that mean that also motor tracts from the extrapyramidal systems can contain pyramidal neurons??? Lova Falk 09:46, 4 November 2007 (UTC)

I believe most neurons that innervate a tract are pyramidal cells, for both the pyramidal and extrapyramidal systems, as they both consist of single-axon bundles and operate with essentially the same long-distance signalling function. I'm not certain, though. SamuelRiv 13:54, 4 November 2007 (UTC)

The pyramidal system got its name from the shape of the corticospinal axon tracts (the axons go through the "pyramids" of the medulla oblongata). Some textbooks do not use the designation "extrapyramidal systems" because functionally the "pyramidal system" actually sends axons to the brain nuclei of the "extrapyramidal" systems, making those systems not really "independent of" the pyramidal system. If you define the "extrapyramidal systems" as constituting the neurons of brain stem motor nuclei and their axons, then that would exclude the cortical pyramidal neurons that project to the brain stem motor nuclei. --JWSchmidt 18:55, 4 November 2007 (UTC)

phone calls

I keep getting calls asking me to press "6"? Are these the calls that seek authorization to place the charge for a long distance call on your number, and if so, why doesn't the phone company make it a priority to notify, if not warn, you of such things? Clem 12:06, 4 November 2007 (UTC)

Do they just call and say 'Please press 6' or do they say anything else? --Ouro (blah blah) 15:47, 4 November 2007 (UTC)

Also, what country do you live in? The meanings of various number sequences differs by phone system. MrRedact 04:23, 5 November 2007 (UTC)

reverse-reverse engineering

Is there a thing called reverse-reverse engineering, where say like a company in England that designs belt sanders for Black & Decker makes a design that has refinements and unnecessary features, and uses excessive and precision parts and is prone to easy destruction, if all but finishing grade belts (100+) are used, that is reverse engineered in China for Chicago Tools, that then is redesigned with no features (variable speed), but a higher RPM that can handle the lowest number belt grit with ease, such that the company in England can then reverse-reverse engineer Chicago's reverse engineered belt sander to come up with a solid and tuff belt sander of its own, with no unnecessary anything, but that is superior to Chicago's belt sander in precision? Or is this just a pipe dream? Dichotomous 12:19, 4 November 2007 (UTC)

Please, next time, use more punctuation. This is basically just an example of reverse engineering something that had already been designed via reverse-engineering. If I understood your mammoth of a question correctly, that is. Cheers, Ouro (blah blah) 12:39, 4 November 2007 (UTC)

You have my permission to punctuate the question to your liking. Dichotomous 13:13, 4 November 2007 (UTC)

Why did you do that? --Ouro (blah blah) 13:21, 4 November 2007 (UTC)

...was at a neighbor's workstation. Dichotomous 13:28, 4 November 2007 (UTC)

Oh, okay. I was just curious. And no, I've no need to punctuate your question. Cheers, Ouro (blah blah) 13:31, 4 November 2007 (UTC)

Please do so anyway for the sake of future questions which might appear on your screen. Sometimes punctuation, like spelling is a very personal or intended thing. Its why we do not utilize an auto-speller bot. I can, however, learn a lot more about you from whatever changes you make. Dichotomous 13:35, 4 November 2007 (UTC)

There. However, if I'd have been the OP, the question'd probably be split into four or so sentences in the least. Bear in mind, I'm not a native speaker of English. Cheers, Ouro (blah blah) 13:51, 4 November 2007 (UTC)

Please feel free to break the question into as many parts as you feel necessary, even if doing so requires re-phrasing the parts of the question. Dichotomous 14:59, 4 November 2007 (UTC)

Also, what is your native language? If you are not familiar with English and possibly more familiar with Spanish, French, German, Italian, Portuguese, Polish, or Korean, et. el. You may be happier responding to questions there. Dichotomous 15:21, 4 November 2007 (UTC)

I'm a native of Poland, but am experienced enough with English and German to use them in any and all situations; furthermore I know some Russian (had it for two years' at University), Czech (having practically lived next door to some Czechs for half a year), and I know Slovak, Croatian, French and Spanish at hitch-hiker level (meaning I know the basic fifty or so words necessary to feel safe when on the road). As for reformatting your question, I'll do it later... I think. Thanks. --Ouro (blah blah) 15:46, 4 November 2007 (UTC)

The term "reverse engineering" is usually reserved for finding out the parts of a design that are hidden - for example the encryption that prevents a US DVD player from playing disks from Japan. Taking design ideas from your competitor (presuming they aren't patented) is simply copying their technology - and I'm sure it's a back-and-forth thing such as you describe. Reverse engineering an already reverse engineered product is not a likely thing since whoever first produced it already knows how it works. Copying the changes someone made when they copied your design is a quite different matter. At any rate, the term "reverse-reverse-engineered" is not one that I've ever heard anyone use - and the only two Google hits I got were both using it in a humerous context. SteveBaker 16:03, 4 November 2007 (UTC)

So then what might one call making changes to a device that would first accommodate low cost high production followed by improvements to maximize quality. For instance, in the example of a belt sander above, the use of stainless instead of galvanized steel for the bottom slide plate and other parts, metal instead of plastic to house the brushes, and ball bearings instead of sleeve bearings, etc., such that the two step cycle of item change results in 1., maximizing simplicity of design and 2., maximizing quality of materials, versus starting with a mediocre or low quality materials item with an unnecessary and extremely complex design? Dichotomous 17:32, 4 November 2007 (UTC)

"Improvements". SteveBaker 18:31, 4 November 2007 (UTC)

QUESTION: Can someone help me locate "one stop" lists of animal species on-line?

Hi,

I am looking for online information similar to that kisted in WikiSpecies, but held together in tables or continuous text format that can be copied into an EXCEL table. I am interested in the species of vertebrates, especially mammals, birds and reptiles. My aim is to be able to create (by as few steps as possible of "copy", "sort" and "delete") a single-table, for example, listing all the lizards and geckos in the world by family, genus, species and sub-species, based on the data in these tables. If such a source of data on species is available, please give me the on-line address.

THANK YOU!!!!

Ron Berger (e-mail address removed to prevent spamming, your welcome) —Preceding unsigned comment added by Bergeronz (talk • contribs) 12:20, 4 November 2007 (UTC)

I just deleted your e-mail address so it wouldn't be found by webcrawlers. I don't know where to find, however, the information you need, and I don't think it will be that easy - you will, after all, have to work a little more than just do simple copying and pasting. Lists of lizards and geckos are in Wikipedia, anyway. Cheers, Ouro (blah blah) 12:36, 4 November 2007 (UTC)

A google search for "taxonomy database" returns some interesting results like [1] and [2]. Since lizards and geckos are easily found under respective families, this should make your database project simple. Formatting into Excel may be a little tricky, given the format of the data at ITIS. In such cases, I recommend writing a computer program (Perl ftw!) or doing some tabbing by hand on a text file before copying into Excel. SamuelRiv 13:40, 4 November 2007 (UTC)

Lawns versus parks

It does not seem that lawns offer any advantage over parks, in terms of a front "lawn." For instance, lawns require mowing, fertilizer, insecticides, etc. while a park uses the materials which die for fertilizer and offers far greater possibly as to variety of species. Park paths can still accommodate mailmen and meter readers who must transverse the yard as well as routes for underground plumbing. Is there any good reason not to turn your lawn into a park besides using it to play batmitten? Dichotomous 15:52, 4 November 2007 (UTC)

This boils down to an argument between public vs. private property. While it seems like a great thing to make everything public, it isn't difficult to find an overwhelming set of examples where private property is better than public property. I live directly across from a park. It is covered in graffiti and full of dog poop. My front yard has no graffiti and no dog poop. So, why should I make my private yard public? -- kainaw™ 17:56, 4 November 2007 (UTC)

I suppose one could turn their front yard into a public park if they were so inclined but I am not referring to a public park but rather the other kind of park instead of having a front lawn. Dichotomous 23:41, 5 November 2007 (UTC)

Could you explain what you mean by "park"? You seem to offer a "park" as an alternative to a lawn of nicely cut grass. Are you asking about paving over your lawn to form a giant parking lot? Or are you asking about letting your lawn overgrow with grasses and weeds? APL 22:10, 4 November 2007 (UTC)

The conventional reference is zeroscaping but this type of landscaping does not necessarily include trees or design features to simulate a park rather than just native flowers and bushes. Even Central Park in NY City has trees and paths and water features that go a bit beyond the limitations of conventional zeroscaping. Dichotomous 23:41, 5 November 2007 (UTC)

megapixel claim

File:Web cam fraud.jpg

I purchased a web cam that claimed to have 6 megapixel resolution. The software that determines the number of bytes per frame indicates YUY2 format at 640 x 480 screen resolution at 614,400 bytes per frame. This sounds more like a 614,400 pixel web cam rather than a 6,000,000 pixel web cam. Have I been ripped off? Clem 16:59, 4 November 2007 (UTC)

Probably. Can you give us the manufacturer and maybe the model? That'd help. Cheers, Ouro (blah blah) 17:24, 4 November 2007 (UTC)

You should do the simplest math yourself: 640*480 = 307200. 614400 bytes per frame means that it has got 2 bytes per pixel. Icek 17:34, 4 November 2007 (UTC)

There is no model number or other means of identification, including even manufacturers name. "USB Video Device" is all that is indicated by Windows XP. The focus can be adjusted. The claim is 10 X Zoom. It says f=3.85 and Megapixel. The actual picture it displays has an extremely irritating color speckle that is highly visible. A sample picture shortly. Clem 17:47, 4 November 2007 (UTC)

I see you've added a sample. Even if the actual maximum resolution was 1280×1024 (which is in the range for current webcams) as you say on the image description page, that's still only 1.3 megapixels, not 6. Besides, if the image is that noisy even at 640×480, I shudder to think what it'll look like at the full resolution. —Ilmari Karonen (talk) 18:27, 4 November 2007 (UTC)

Besides, that image looks like it's actually been scaled up from something like 320×240! You can easily see the 2×2 pixel blocks! —Ilmari Karonen (talk) 18:32, 4 November 2007 (UTC)

6 megapixels for a webcam sounds unlikely to me; that's a typical resolution for compact digital still cameras these days. The resolution of webcams is limited not just by their typically low cost and the higher demands put on the sensor by video recording as opposed to still photography, but also by the fact that, as the name suggests, their output is typically intended for streaming over relatively low-bandwidth links. —Ilmari Karonen (talk) 18:22, 4 November 2007 (UTC)

It certainly sounds like you've been ripped off. 640x480 is a third of a million pixels - my guess is that they are 'stretching' by claiming something like "6 million pixels per second" (which would mean you're getting a disappointing 18Hz frame rate). Two bytes per pixel suggests you're only getting 65536 colours per pixel too - which is also distinctly disappointing. But in truth, a movie camera that could produce 6Mpixels and a minimal 20Hz frame rate with full colour would be 360 Mbytes/sec - which is more than a 1GHz Ethernet could transmit - and VASTLY more data than your home network could possibly transfer anyway. So a 6 megapixel web camera is really an impossibility. 640x480 is a pretty reasonable resolution for a WebCam. The noise you are seeing is indeed unacceptable - but what you have there is a crap camera. SteveBaker 18:29, 4 November 2007 (UTC)

You can find these on eBay from smartarea and ecool. Ecool is new but smartarea is a power seller. Both are located at the identical address and request buyers contact them first if any problem rather than leaving negative feedback first. Apparently their strategy works. Dichotomous 19:37, 4 November 2007 (UTC)

weird clock

Hi. There was a clock which had batteries that almost ran out, a digital clock. Sometimes, when I put it in the correct place (there was a turned-off computer, a prniter, and a metal spoon nearby), and put my finger-hand near, but not touching, the digital clock, its screen would flash with dim numbers and sometimes make clicking sounds. This rarely happened when my hand wasn't near the clock, so much so that I believe the chances that this is a coincidence is extremely small. Sometimes, if I picked up the clock, and put it near the reigon where this happened, it would flash again. I mean "flash" as in the black numbers flash on and off. Sometimes the effect is so weak that only the background of the numbers would appear. Now, when I put this clock between two computers, the effect doesn't show up, and when I put it near an "on" computer, it also flashes. When I took the spoon away, it still flashed, but has since stopped clicking. What could cause this? Is it because humans and electronic devices emit EMF's? Thanks. ~AH1^(TCU) 17:11, 4 November 2007 (UTC)

I'm betting on coincidence. Humans don't "emit EMF's". SteveBaker 18:21, 4 November 2007 (UTC)

Humans don't emit EMF themselves, but we do affect the electromagnetic fields around us due to being large conductive objects. You can easily observe this by tuning an FM radio to a station that it can barely receive; often moving your body around will audibly affect the reception quality. (This is also how a Theremin works.) From AstroHurricane001's description, it does sound like the clock was picking up some local EM interference that was inducing just enough current to cause the observed effect (it doesn't necessarily take much). —Ilmari Karonen (talk) 18:46, 4 November 2007 (UTC)

I'll say 95% that this was no coincidence. I tested this for aboout 15 minutes, and putting my hand over it produced an effect whereas not putting my hand there did not. Usually, I leave my hand, nothing. I put my hand there, it happens. I withdraw my hand, nothing. However, it does seem to throb lightly when I put it really close to a computer without brushing my hand over it, but putting my hand over it will produce a strong effect. Could it be that, as the computer emits an EMF, and I put my hand over it, it conducts the current to the near-dead battery? Amazingly, it has come back to life, but is still many hours off. Could it be that the battery terminals are so on the line between connected and not connected, a little interference can turn it on or off? Thanks. ~AH1^(TCU) 02:37, 5 November 2007 (UTC)

Liquid crystal displays can be activated by stray electrostatic fields such as might be present on your fingers, but this would only occur at very close distances. They can also be affected by pressure, but that would require contact.

Atlant 17:13, 5 November 2007 (UTC)

Charged Black Holes

How does an electrically charged black hole 'show' its charge? I was under the impression that information about an object's electric charge was carried by an electromagnetic field. If the gravity of a black hole is strong enough to prevent electromagnetic radiation (light) from escaping the event horizon, then how does the electric charge 'leave' the event horizon? Smithg86 19:17, 4 November 2007 (UTC)

The electric field lines do not leave the balck hole, instead they are there before the formation of the blackhole, and are not destroyed by the formation. You get it when an electrically charged mass collapses. Graeme Bartlett 20:46, 4 November 2007 (UTC)

Question about black headed gulls

Why do they sometimes seem more interested in fighting with other black headed gulls than eating from a pile of food? Someone had thrown some bread out for them today and I was watching them. The gulls didn't even seem that bothered about the food. They were just sitting on the surrounding rooftops looking at it.

Another black headed gull flew in from somewhere and decided to come down and eat. As soon as that happened, a load of gulls swooped down from the roof to attack the eating gull and chase it away, then they started fighting among themselves, leaving the bread alone (it's still there now). What was the point of all that? I don't get it. —Preceding unsigned comment added by 81.77.30.145 (talk) 20:52, 4 November 2007 (UTC)

Well, if the bread's just sitting there, I suppose whoever eventually wins the fight can then come back and eat it. But I suspect there is more to it than that. The response you describe sounds like an escalated retaliation to punish some sort of perceived misbehavior or social transgression. Such retaliation is observed in many species, including humans: if someone attacks our country, we'll fight back even if it hurts us more than the initial attack did. In the case of interpersonal disputes we've institutionalized this in the form of law enforcement, but the principle is still the same (and where law enforcement breaks down, we still get things like gang wars and vendettas). In this case, the obvious possibility that comes to mind is that the gull that flew in was an outsider while the ones that attacked it considered the area as their territory, but I don't know enough about gull social organization to say if that explanation really fits. —Ilmari Karonen (talk) 02:04, 5 November 2007 (UTC)

Gulls have three principal interests - feeding, fighting and fucking. In that order. If they're not particularly hungry at that moment in time and there are several gulls in the same location, keeping an eye on the food - then why not take the opportunity to cement/re-jig the pecking order with lots of gratuitous bickering, flapping, pecking and chasing? Another classic gull behaviour is fighting to displace each other from the highest perches/perches with the best view - lots of swooping and screeching. I was watching the BHGs near my house doing that today. They could squabble over one chimney pot for hours if they had nothing better to do - or until a bigger gull came along and claimed it (as happened this afternoon). Quite amusing, really - all the Black-Heads just backed off, sidled over to the opposite end of the roof and shut up when a Great Black-Backed Gull arrived, took the perch without a fuss, postured at them a little bit and then decided to settle down for a nap.--Kurt Shaped Box 00:18, 6 November 2007 (UTC)

Your note about the displacement behavior reminds me of a funny incident I observed while sailing with some friends recently. We were coming up slowly to a bend in a narrow boat lane, with four small sea marks (basically plastic poles sticking out of the water) marking the boundaries of the lane. Three of the closest poles had a small juvenile gull each sitting on them. (My memory is fuzzy here, they may have been either Common Gulls or black-heads.) When we passed the first marker, the gull on it took flight. It flew to the next pole and settled there, displacing the gull that was already there. That gull then flew to the third pole and displaced the gull there, who finally flew to the fourth, unoccupied pole and settled there.

At that point I was watching the gulls' antics and laughing aloud, so the others asked me what was funny. As I was explaining the previous events, we passed the second marker pole, and, sure enough, the gull on top of it again took flight, heading for the next pole, and the whole game of musical chairs repeated itself. This time, however, the last gull, not having any further poles ahead to land on, took a wide and graceful turn across the lane and headed straight back for the pole the first gull had just landed on. The first gull, displaced for the second (or third if you count the previous incident) time, then flew back around our boat and onto the pole he'd first been sitting on.

Being all academics, the conclusion we drew from this observation was that the displacement process was intransitive: it's not a matter of a bigger or higher-ranking gull displacing a weaker one, but simply that, if another gull wants to land on an occupied pole, the gull already there must give way unless he wants the other one to land on top of him. —Ilmari Karonen (talk) 05:15, 6 November 2007 (UTC)

They don't always give way. Sometimes the gull on the perch will assume a defensive position (body lowered, wings spread slightly, beak pointing upwards) and attempt to fend off the 'landing' gull with a few quick jabs of the beak in its general direction. More often than not, the 'landing' gull will see this, decide not to engage in a physical confrontation, pull up and away and then circle around, looking for somewhere else to stand. Very occasionally, a bout of beak-locked, wing-pummelling combat *does* ensue, however. I'm certain that (maybe only in certain situations) there is a pecking order aspect to it too.

Quite likely there is. The three fellows I observed were all juveniles of similar age, quite possibly siblings. I'm sure none of them would've tried displacing, say, a full-grown Herring Gull from its perch. Still, it's interesting that, all other things being equal, the displacing gull has such an advantage that the one already on the perch won't even try to hold its place. Or perhaps it's "gull manners"; the landing gull may, on average, tend to be more tired and thus more willing to press the issue, so it may be better for the one who's already rested to give way and avoid a needless conflict. After all, he can always come back and invade the same perch again if necessary. Or perhaps both explanations may play a role. —Ilmari Karonen (talk) 19:39, 6 November 2007 (UTC)

The type of perch may have something to do with it too. On my road for example, there are certain perches that the gulls seem to favour more than others and 'compete' over regularly. Invariably, they're the highest points on the rooftops and certain lampposts. It's not *all* high places and *all* lampposts though, so it may be something to do with the view of the surrounding area from said perches. I don't know if this is true for BHGs - but the local GBBs also definitely have their own favourite perches that pretty much go undisputed (I recognise most of the individual birds now). In the case of the gull I raised as a chick, the whole roof opposite the back of my home is *her* roof (in summer, her nest goes on a flat section there). That's not to say that other birds (of various species) don't ever perch there - just that they don't when she's present and keeping watch. --Kurt Shaped Box 22:05, 6 November 2007 (UTC)

Have you ever noticed several Black-headed Gulls stood upon the apex of a single, longish roof? They tend to space themselves apart at very regular intervals - approx 18 inches between each bird (more if possible). If one bird decides to shuffle along a little bit (and provided that this doesn't immediately cause a fight), the next bird shuffles along a little bit, causing the next bird to shuffle along a little bit, causing the next bird to shuffle along a little bit, etc. If the final bird on the roof has nowhere to shuffle to that would allow it to remain 18 inches or so from its flockmate - it takes flight and circles around to the other side of the roof and tries its luck there! Just speculation here - but 18 inches is quite possibly the distance that one Black-headed Gull can lunge in the time it takes for another Black-headed Gull to react. --Kurt Shaped Box 19:07, 6 November 2007 (UTC)

Another possible explanation that occurs to me is that 18 inches is about half a Black-headed Gull's wingspan. It may be advantageous to keep enough distance to your neighbors so that your wings won't bump into them while taking off (or vice versa). —Ilmari Karonen (talk) 19:39, 6 November 2007 (UTC)