Wikipedia:Reference desk/Archives/Science/2007 February 1

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February 1

Project

For our project at Uni, we have been asked to pick an animal to make extinct and argue our case. It has to be a vertibrate and not man. I dont want to pick panda cos it is too obvious and it doesnt really do any harm, does it? It should be preferrably something that does harm to the environment or nature or something. I thought beaver or something. Do you agree? Any further suggestions and why?

Beavers have a huge impact on ecosystems, providing wetlands for many other species to use, so removing them would probably have many repercussions. From a purely pragmatic and uninformed point of view, I would argue for the extinction of a species that is critically endangered or extinct in the wild, as I would imagine this would have the lowest impact on the planet's eco-system as a whole. Flipping the assignment on its head, you could go the satirical route and argue for the extinction of a species that would cause as large of an impact/disaster as possible, in effect showing that everything plays their part. Atropos235 01:20, 1 February 2007 (UTC)

The ranchers in the American West are after timber wolf (a.k.a. gray wolf) again; they want to see it extinct in their area again. American suburbians everywhere think the coyotes should all die.

Atlant 01:21, 1 February 2007 (UTC)

Nah! I go for the Roadrunner!--Light current 01:33, 1 February 2007 (UTC)

The safest thing to pick is a parasite. Not to sound utterly heartless, but humans are by far the most damaging parasite. But then, I like history and culture and being alive enough that I wouldn't want to wish the end of all humanity. This is a tough call for anyone to make. Think about the environmental impact removing a single animal would do. 67.174.211.89 06:00, 1 February 2007 (UTC)

I'd pick an introduced species, like the cane toad, and argue that it's value in it's native ecosystem is trumped by it's impact on it's introduced ecosystem. --Cody.Pope 06:54, 1 February 2007 (UTC)

What about the dreaded mosquito? | AndonicO ^{Talk · Sign Here} 11:39, 1 February 2007 (UTC)

Unfortunately, our questioner is limited to vertebrates. Otherwise, the mosquito is the obvious choice.

Atlant 13:10, 1 February 2007 (UTC)

You can really pick anything you want. It doesn't even matter. Species are rising, falling, gaining, being pushed back, bottlenecking, exploding, all the time everyday. It is simply the way of nature to kill off species. It may not be nice, but that's just how it is. That is normal, and it is change. It is absurd to try and do something with the intention of changing nothing, because the environment will change on its own, it doesn't matter what part of the environment changes it (may it be a particular species), because each species is part of nature. Since we are being so inherently anthropocentric, you can say humans have helped some species, and humans have destroyed some species, directly or indirectly. We can relate alien species invasion since it is the opposite of entirely removing a species. Both on the same continent and at the same time Bos taurus was being bred in vast quantities, while Bison bison was being hunted to near-extinction. Cattle are aliens too, and are among the most destructive friends we tend. The grazing and trampling of livestock threaten more than three and a half times as many native plant species globally as are threatened by nondomesticated aliens. Livestock threaten almost as many native animal species as alien predators do. Pueraria montana is an Asian plant despised in the southeastern states for aggressive growth. American gardeners of the late 1800s loved its fragrant blossoms, and in the 1920s it was promoted as Bos torus chow, and in the 30s widely planted by the Soil Conservation Service for erosion control. The Department of Agriculture declared it a weed in 1972. Similar in history, Taraxacum officinale, or "common dandelion" was introduced to North America from Eurasia for its medicinal and culinary properties. Even if you don't agree with me, you perhaps should mention it to bring something new to the table. [Mαc Δαvιs] X (How's my driving?) ❖ 12:24, 1 February 2007 (UTC)

Vertebrate eh? I'd pick the Panda. Think about all the resources, time & money that have been squandered to protect or preserve a species that has become so specialized that even without our intervention, was likely to become extinct in the very near future. Are there even enough Panda's left to sustain a genetically diverse viable population? Now if those same resources had been applied to a species not quite so cute and cuddley perhaps the passenger pigeon, great auk, or any now extinct species you can name might still be with us. This then brings into question the entire reason why we choose to protect some species while ignoring others? If the Panda was an ugly mollusc that crawled up your leg and bit you on the ass, would we be so willing to protect it? Extinction is a natural process. It is not that extinction occurs that should concern us rather, the acclerated rate of extinction that we as a species seem to be responsible for. Canis sylvaticus

How about the Water moccasin or Copperhead snake?, or maybe the Rattlesnake? Your study could look at whether nonvenomous species could step up to replace their pest control benefits without harming humans. In other words, would we be overrun by rats and mice without the venomous snakes, or could the less harmful species take care of the pests. These species do harm humans and their pets and livestock, and the water moccasin and copperhead snakes make the enjoyment of the outdoors difficult in the southern US in the summer, as the rattlesnake does in the west. I acknowledge that many people love all animals, and that they are all pretty to look at, unless you have just stepped over a log and they have sunk their fangs into your leg. (edited to add: Here I refer to the snakes, not the animal lovers as biters). Keep the panda. They do not bite humans as often, and are not known to be venomous. Edison 16:38, 1 February 2007 (UTC)

Human deaths from venomous snake bites in the USA (those species in particular are US snakes, yes?) are so uncommon today as to be statistically negligible. You get far more deaths from dog bites per year, more deaths related to riding the bus. --140.247.248.95 17:33, 1 February 2007 (UTC)

Country people in the southern U.S. avoid wooded or grassy areas, or creekbanks in the southern US in weather above freezing because of the presence of copperheads. They are numerous and aggressive, and like to live near human habitation, and move into outbuildings or onto farm equipment. I have had several close calls. Besides deaths, they cause painful injuries with lengthy recuperation. No one claimed that poisonous snakes are leading cause of deaths, and more people obviously ride buses that step on copperheads. Dogs are domesticated pets and offer the benefit of companionship or guarding as a tradeoff for the chances of biting soemone. Copperheads make poor pets, but if it were known that they lived in a building, people would, I guess, pretty much stay out. Edison 21:43, 1 February 2007 (UTC)

I'm just pointing out that you'd have to indicate that the number of lives you'd be saving would be in the dozens, whereas the likely ecological damage would be quite high. In terms of cost/benefit the panda is an easy one in comparison to the venomous snakes of the US, which cost very little (in terms of human costs and resources) to live with. The panda's non-venomous quality does not really give it an edge over the snakes in a strictly utilitarian model. --24.147.86.187 00:22, 2 February 2007 (UTC)

I'm sure if you made your presentation on a list of animals you initially thought you might like to make extinct, then talked about what made you reconsider, and concluded the whole exericse to be abhorrent, you would not receive an autofail. That's what I'd do. Vranak

---

I would pick the goat or the Norway Rat. Goats devastate ecosystems, and rats have a huge impact on humans. The one you pick will depend on your perspective. -Arch dude 02:39, 2 February 2007 (UTC)

If you want to be a smartass you could go for the Madagascar Pochard. The rationale being that everyone thought it was extinct 15 years ago anyway, and the world kept turning. Then a few of them were spotted last year. However, they are clearly critically endangered and - one could argue - removing the few remaining would have a negligible environmental impact. The opposing argument is that the Madagascar flora and fauna is rich in genetic diversity. Rockpocket 06:21, 2 February 2007 (UTC)

Excellent idea! Frilled shark, Megamouth, coelacanth, and Lazarus taxon. [Mαc Δαvιs] X (How's my driving?) ❖ 18:03, 2 February 2007 (UTC)

And the Tazmanian wolf

purifying water and sourdough

I have recently heard that the brewing industry use to use sourdough (from bread) to purify water. I wondered if there was anyone who could validate this. Also, how does it work? Thanks Valerie

Sourdough bread is bread that is leavened with sourdough starter, a symbiotic colony of yeast and bacteria (lactobacilli). The closest to "purifing" water might be the microorganisms living in the starter form somewhat hostile conditions to "squeeze out" other potential micro-invaders.That process is fairly slow and complex compared to filtering water through activated charcoal or distillation, and you'd end up with a bunch of floury water. I'm not a big beer aficionado, but using some sourdough starter in a ferment might impart some of the same acidic, complex flavors you can get in sourdough bread. Atropos235 02:44, 1 February 2007 (UTC)

Is it at all possible that this is a garbled version of the idea that alcoholic drinks were once drunk in great quantity because they were less likely to poison you than the water? That was mostly (if not entirely) due to the boiling involved in the production of alcoholic drinks. Skittle 15:36, 1 February 2007 (UTC)

Petroleum Oil

I am doing a science fair project for my 8th grade class. My question that i want to ask you is this: What is oil's real purpose in the Earth? Does is it act like some sort of insultaor or anything else? I mean, everthing on this Earth is here for a purpose. I am stuck and do not know what to do. I found one website that asked the same question to but did not have any information that I needed. {Please Help Me} 4.129.87.148 00:57, 1 February 2007 (UTC)

Oil wasn't intentionally placed into the Earth for any sort of reason, but it is just the result of dead biomatter being compressed and heated under millions of years of sediment. Man's persistant exploration of the world lead to the discovery of petroleum and its seemingly millions of uses over the ages, from lighting up ancient homes to sending people to the moon. It can easily seem like everything in the world has a purpose because we are the ultimate tool-users and we can find a purpose for just about anything. Atropos235 01:36, 1 February 2007 (UTC)

For all we can tell, purpose is not inherently present on anything. There's no purpose for the existence and presence of oil, or even life, on Earth. It exists because that's how chemistry and physics work. Things also tend to naturally find their most stable state throughout time, so the feeling of deliberation and purpose arises naturally everywhere, since everything ends up fitting together so well. That being said, oil has no purpose, we just happen to find it very, very useful for many different things. — Kieff | Talk 01:44, 1 February 2007 (UTC)

The scientific way to phrase it is that purpose is not scientifically testable in experiment and therefore not relevant in a scientific sense. However, to absolutely claim there is no purpose is making a leap that science cannot explain so claiming there is no purpose or deliberation goes beyond the scientific method. --OpusPenguin 03:17, 1 February 2007 (UTC)

I personally believe "everything having a purpose" to be rubbish. As Richard Dawkins said, "We see the world through purpose-colored spectacles," because our nature is to see objects of having potential uses to us, we assume if we can't use it, it has a use to some other organism. [Mαc Δαvιs] X (How's my driving?) ❖ 12:17, 1 February 2007 (UTC)

See Teleology for a discussion of the old notion that someone (God?) placed everything herre for a purpose. This view might say that if I am hiking and have to make a pitstop in the woods, that my excrement is there for the purpose of nourishing a bush which will grow into a tree and provide shelter for some future weary travellor. A less teleological and more naturalistic view might be that "excrement happens." Edison 16:44, 1 February 2007 (UTC)

If you were to put any purpose to oil, surely it would be to warm up the Earth, not that there's anything wrong with that. Vranak

You are in 8th grade. Teleology is usually considered to be way too heavy for your age: Plato thought that one should not be concerned with Philosophy until age 40. Science fair: you are probably in time trouble: you don't need generalities, you need an answer, NOW. Here is what we are trying to tell you in simple terms:

• forget "purpose." That is way too complicated. It is philosophy, not science.
• Try to rephrase your hypothesis into something more scientific and less philosophical.

If you can reply with your current hypothesis, We can probably critique it for you and suggest a better hypothesis. I just got home from judging a high-school Science Fair, so I am sympathetic. -Arch dude 02:33, 2 February 2007 (UTC)

What did Plato know? Him and his ilk never understood inertia nor evolution nor planetary harmonics. Nonetheless, the above statements correctly emphasize that purpose is not testable and has no place in science. We can study much about petroleum - how it forms, what it is made of, what we can make out of it... but none of this implies a purpose. However, I think the original question was asking whether there petroleum performs a geological function - such as "insulating. "Petroleum reserves do not really insulate very much; but they contain lots of dissolved gases (notably, helium, sometimes hydrogen, and very often methane or other natural gas.They also serve as boundaries between rock layers (though this is probably an effect due to their formation). Nimur 08:05, 2 February 2007 (UTC)

Since no one actually gave the simple answer to your questions, I will: The purpose of the oil is for people to burn it for fuel. Do you think it needs some other reason to be there? Ariel. 13:11, 4 February 2007 (UTC)

Database for lab experiments

Hello, I am currently working on my PhD in the biopharmaceutical field. I am doing a number of lab experiments and I am looking for a way to store information about the experiments and the outcomes in a database.

Typical data about an experiment would be: Title, notes, Dates (when run, when analysed), material used, method used (i.e. word files), raw data (i.e. sampling points), secondary data (i.e. halflifes), graphs.

I have attempted to come up with an MSAccess solution, it works more or less but it has its bugs and entering data can be somewhat time consuming.

I was wondering if anyone knows a flexible tool to handle this kind of task. (I think there should be, since the core of what I need it to do is probably needed by uncountable other people working in similar areas. I haven't really found anything practical so far though).

Thanks, Lukas 04:32, 1 February 2007 (UTC)

Honestly, I'd use a spreadsheet if you don't have any prior experience with RDBMSes. Spreadsheet software is very flexible and useful for sufficiently small amounts of data. Most of the data I need to process goes directly from my notebooks into a spreadsheet program. -- mattb @ 2007-02-01T05:50Z

I don't think you could include all of the data he wants in just that. However it sounds to me like it is a flat database anyway, so you don't necessarily need it to be relational. Have you tried something like FileMaker Pro? It is like MS Access but much simpler on the whole. It doesn't let you do as complicated or customized things with the data but it doesn't sound like you are using Access to its full capabilities anyway. Access is probably the most "flexible" thing you are going to find, but being able to use that capability well requires a lot of time and experience with it. If you wanted to post the nature of the bugs to the computing desk, I am betting we can iron out some of them (I say this as someone who has wrestled with Access for eight years or so at this point). --24.147.86.187 12:49, 1 February 2007 (UTC)

Well, he didn't specify how much data he is working with...If we're talking single data sets with a million rows, then a spreadsheet will be insufficient. A few thousand rows is reasonable, though. -- mattb @ 2007-02-01T15:08Z

I'm not talking about total records. Look at the types of data he describes -- Word files, lengthy descriptions, etc. It is not easy to do that in a spreadsheet program, at least not any I have seen. The lines get very long and hard to read, use, and edit. --140.247.248.95 17:27, 1 February 2007 (UTC)

Need to share the data among workers ? Why not try a hosted DB solution like www.teamdesk.net at 7 $ / month / user. I found it easy to customize. Pcarbonn 16:03, 1 February 2007 (UTC)

Be very careful when using spreadsheets to store experiment results. See for instance The December 1 DWIM effect (reported on RISKS Digest 24.19; some comments on 24.20 and 24.21). Some other spreadsheet horror stories can be found at the European Spreadsheet Risks Interest Group site. --cesarb 18:57, 1 February 2007 (UTC)

Thanks for the replies so far. Especially thanks for the warning on excel, I've encountered some bugs in it myself before. Excel/spreadsheed is not a viable option for me. The reason to use the database is, as correctly pointed out, not that I have thousands of records, but that I have descriptive text data, files, etc. I do not need to share the data (and I don't see that happening within this project). I want to be able to easily enter data into a form and retrieve data matching certain characteristics (this is what I have attempted in my test database (msaccess2002). One thing it should take over is the task to think of where I should save which files and make it easy for me to find them again. I'm still looking for a product or an msaccess template which is designed for this or a similar purpose (there are should be tons of other people out there with similar requirements as me....). Lukas 01:47, 2 February 2007 (UTC)

Having a look at the teamdesk thing, too. Thanks Lukas 01:51, 2 February 2007 (UTC)

Many computer science types make a hefty profit handling other people's databases, because to even this day it gets messy and application-specific. Though numerous utilities exist (MySQL, MS Access, etc) which supposedly make managing data "simple(r)", I don't know of any that make the solution "user-friendly" to an inexperienced operator. It may be worth paying a fee to an outside service provider, or hire an undergraduate CS intern, if you are unable to develop a complete solution on your own. Nimur 08:11, 2 February 2007 (UTC)

Squid Brains and CNS?

Hello all!

I was talking to a friend recently who said that he couldn't understand how it worked, not being scientifically oriented, but that while in Japan he had been told that the liquid he was eating was squid brain, and that it was a liquid. This puzzled us both, as I, too, have not studied marine biology in great depth. Any idea if a) the brain really is liquid, and b) if so, how does the nervous system of a squid work? I know they are invertebrates, but that's about it. The Squid article doesn't seem to reap much information. 67.174.211.89 05:57, 1 February 2007 (UTC)

And hello to you too. Your brain is about 60% water, and can be liquified in a blender and is considered a gastronomic delicacy on R'tyrovkv in the Betegeuse system (lucky for us they are so far away). The unique thing about squid neurons from a neurophysiologist's point of view is that the individual axons are unusually large and were heavily used in the 1960s-80s to study depolarization and potential propagation. They work basically the same way your neurons work. alteripse 10:45, 1 February 2007 (UTC)

Some more info is at Squid giant axon. --David Iberri (talk) 18:04, 1 February 2007 (UTC)

On the brain into a liquid tangent, ancient Egyptians removed the brains in their mummification process by sticking a flexible tube up their nose and jiggling it several times to turn it into a mush, which was easily extracted from the cadaver from the nostril. bibliomaniac15 01:45, 2 February 2007 (UTC)

The brains of squids, like all other invertebrates, lack a myelin sheath. Not sure if this would affect the taste or texture of the brain from a culinary perspective however. Mikmd 17:55, 5 February 2007 (UTC)

After reading the myelin article, and the references, it seems that squids may have some form of myelin after all. However, it seems to have evolved independently from vertebrate myelin. Mikmd 18:05, 5 February 2007 (UTC)

I'd never heard of a "squid brain paste" food here in Japan so I looked it up, and the only thing I can find close is shiokara. It IS a liquid of sorts, but as far as I know there is no variety that is purely made of squid brains (though the brains are most certainly included with the rest of the pureed, fermented squid).  freshofftheufoΓΛĿЌ  05:18, 2 February 2007 (UTC)

Top 10 Engineering Projects With The Most Human Fatalities?

Hello wikipedians,

My brother in law and I were discussing the top 10 human engineering projects with the most fatalities. So far we have come up with the Death Railway (116,000 deaths of workers) and the Panama_Canal (27,500 deaths of workers).

What other engineering projects would be in the top 10?

Incomplete or unfinished projects are fine.

We are more interested in projects that have fairly specific numbers. For example, we know that lots of people died making the pyramids of Egypt but for obvious reasons we will never really know even approximate figures.

Thanks in advance, Kategorian 11:21, 1 February 2007 (UTC)

Interesting question. I suppose one would have to look at the oldest major engineering works, such as dams and canals. Searching Wikipedia for "workers died" suggests that 120,000 people died during construction of the Suez Canal, and 80,000 during the building of "the British railtrack" in Egypt.--Shantavira 11:55, 1 February 2007 (UTC)

Chinese urban myth claims that thousands upon thousands of people died while building the Great Wall. There are songs and stories that claim human meat and bone was used for the mortar. However, those horror stories have very little evidence to back them up. --Kainaw ^(talk) 12:52, 1 February 2007 (UTC)

You might also look into massive modern works produced in socialist countries in the 1940s and 1950s. I don't know whether many workers died in the construction of the dam on the Dnieper river, for example, or Magnetogorsk, but I would be surprised if they were bloodless, having been constructed with Gulag labor. --24.147.86.187 12:59, 1 February 2007 (UTC)

The Trans-Siberian railroad has to be a candidate. Clarityfiend 15:56, 1 February 2007 (UTC)

The production of military goods for the German army in WW2 should count as an engineering project, and very many imprisoned workers died in it, including death camp inmates and persons from occupied countries. China's Great Leap Forward was an engineering program to make China into a leading industrial country. It took a great many lives: villagers were told to make steel in little backyard furnaces by burning their doors and furniture and all trees as fuel, and all they managed was to convert their plows and pots into lumps of molten iron. The harvests were neglected, and in a pretense that agricultural yields had increased, the actual small harvests wer seized for export. The death toll is stated in the article as 14 to 43 million excess deaths. Edison 17:12, 1 February 2007 (UTC)

Among single construction projects in modern times, the White Sea-Baltic Canal has to rank pretty high.--Rallette 17:55, 1 February 2007 (UTC)

Cigarette lighters

why cigarrette lighter cant be lit by smouldering cigarette? —The preceding unsigned comment was added by 221.134.57.69 (talk • contribs). (Arun singh Bagh)

Basicalliy it seems that smouldering cigarrete is not hot enought to rase the gas temp above the critical temerature. See flash point for some info on this.--Light current 16:44, 1 February 2007 (UTC)

There was an episode of MythBusters where they featured a popular Hollywood myth, that dropping a lit (smoldering) cigarette into a pool of gasoline could ignite it. They were never able to make it happen, but deemed it plausible because the temperature of the cigarette was hotter than the flash point of gas so it "could" happen. I've also heard of anecdotes of people putting out cigarettes in jet fuel (similar to kerosene or diesel). Atropos235 18:25, 1 February 2007 (UTC)

Yep - the lighter hydrocarbons are always easier to light - lighter gas is propane or butane, the flash point increases with molecular mass. And yes kerosene and diesel are difficult to light, especially diesel - you ever need a wick or otherwise it helps if you heat it in a frying pan first until it starts smoldering - then it lights easily..

Plus a straight cigarette contains significant amounts of nitrate to get sudden flashes of high temperature as the tobacco impregnated with the nitrate burns - these are like little sparks and help ignite things. A 'roll your own' cigarette doesn't have this nitrate and burns much colder and is less likely to ignite a lighter flame - in general they don't..87.102.77.95 19:30, 1 February 2007 (UTC)

Sodium vapour lamps

why sodium vapour lamps are used for street lights? —The preceding unsigned comment was added by 221.134.57.69 (talk • contribs). (Arun singh Bagh)

The most amount of light for the least amount of electricity. See Sodium vapor lamp.

Atlant 16:14, 1 February 2007 (UTC)

High efficacy?--Light current 16:37, 1 February 2007 (UTC)

From a desire to make everything look yellowish with monochromatic 590 nm illumination, to make the skies over cities look orange, or to save electricity. Edison 17:15, 1 February 2007 (UTC)

its gotta be efficacy. If someone invented a higher efficacy green light, our night skies would turn green.--Light current 18:33, 1 February 2007 (UTC)

One consideration is that low-pressure sodium-vapor lamps are good for astronomers, because their light pollution can easily be filtered out (that's because they're so nearly monochromatic; you just have to block that one single line). In my opinion they're also less ugly than high-pressure sodium-vapor lamps (those are the pink ones). --Trovatore 18:37, 1 February 2007 (UTC)

It's what we already have, and would cost too much to replace all of them:)Hidden secret 7 19:40, 1 February 2007 (UTC)

Xenon arc lamp

New lamps can vary greatly. I've seen several recently which look to be high-intensity fluorescent lights (sort of like the Compact_fluorescent_light_bulb soft-glow lightbulbs. And of course xenon arc lamps are used, especially on high traffic highways.

Sorry, no. A variation on xenon arc lamps may be in your car's headlamps, but they're not used for overhead lighting on highways (because sodium vapo[u]r lighting is so much more efficacious).

Atlant 14:10, 2 February 2007 (UTC)

Chlorophyll efficiency

Is there some reason why the green part of the visible spectrum is not absorbed by chlorophyll and associated pigments? Why is chlorophyll able to absorb only red and blue light? Would a more efficient system absorb all visible light? —Preceding unsigned comment added by 220.236.73.126 (talk • contribs)

I'm not sure, but at a guess I would say that plants just doesn't need to. They get sufficient energy from the wavelengths that they do absorb. Also, if plants were absorbing all wavelengths in the visible spectrum, they would probably overheat. (And who wants a world full of black plants anyway?) BenC7 07:14, 2 February 2007 (UTC)

I think the best way to explain this is that "nature" didn't just engineer the optimum system. It evolved this way, probably based on prior chemical reactions. I'm not entirely sure how the chemical reaction operates, but it very likely cannot use any arbitrary energy, requiring specific frequencies to serve as activation energy for chemical changes. Nimur 08:22, 2 February 2007 (UTC)

• Chlorophyll is green. The reason we can observe that is because it doesn't get absorbed. If it did, it wouldn't be green anymore. - Mgm|^(talk) 11:09, 2 February 2007 (UTC)

Don't some plants already have black leaves

Plants have several photosynthetic ("light absorbing") pigments. Clorophyll a absorbs red, and clorophyll b absorbs blue. Why these colors were favoured by plants is simple: they weren't. Plants simple used whatever molecules evolution made available to them (efficiency of the molecules also played a role; there are green absorbing pigments, and pigments that absorb wider ranges of the spectrum, but they aren't as efficient as clorophyll). Go here for more information and neat charts: http://users.rcn.com/jkimball.ma.ultranet/BiologyPages/A/ActionSpectrum.html Pedro Almada

Body Changes

I am not sure how to phrase this correctly nor have the proper terminology, but my question is:Is it possible that your genetic makeup can change throughout your life. When I was a child, I remember having very straight hair and I longed for curly hair. However, in my early 20's, my hair became very thick and curly. Now, I am in my mid 30's and my hair changing it's structure again. It is becoming straighter. Any ideas?

It is not possible for your genetic makeup to change (aside from random DNA mutation that would likely only result in damaged or cancerous individual cell populations). There are many reasons why your hair might be changing structure, including age, changes in diet, or moving to a different climate. It's not at the DNA level. -- Scientizzle 16:28, 1 February 2007 (UTC)

This is probably common knowledge to anyone who has taken high school biology, but I couldn't locate anything in our article on DNA that says as much. Vranak

It is hard to believe that the dramatic changes of my hair structure was from what I ate or where I lived.Please understand that I had pin straight hair (similar to Asian hair) when I was 8 but by the time I was 21, it was very thick and curly...

Though I've never heard of what you describe specifically, hair does respond in a variety of way to the levels of certain hormones that increase during puberty/maturation and fall off during middle age.See Hair#Growth.Dragons flight 17:46, 1 February 2007 (UTC)

It isn't just puberty, my hair has been getting darker from light blond to a very dark brown at least since I was born:)Hidden secret 7 19:44, 1 February 2007 (UTC)

It's very common for light hair to get darker through childhood - lots of kids are born with blond hair but don't keep it - blond kids are usually born with very white hair. I don't know if this means you will go platinum in later years or not. It's common in the animal world for juveniles to have a different colouration to adults.87.102.77.95 19:56, 1 February 2007 (UTC)

As for your hair changing from curly to straight again - don't know.87.102.77.95 19:58, 1 February 2007 (UTC)

I always thought it was strange that my hair behaved this way.Someone mentioned that our skin(?) completely changes every 7 years and maybe so with hair texture.Maybe I am not human!

I don't think I am either:)Hidden secret 7 20:50, 1 February 2007 (UTC)

There is one important exception to the rule that your DNA doesn't change during life, which applies to cells of the immune system, i.e. B lymphocytes and T lymphocytes. During maturation, the DNA coding for these cells' receptors is rearranged, see VDJ recombination. The changed DNA is inherited by daughter cells. The rearrangement occurs in a random fashion, and because various fragments are involved, each of which comes in a large number of variants, combinatorics ensures that the number of different receptors is formidable. In addition, there are enzymes that insert non-coded nucleotides at the points where the DNA is spliced. The potential number of antigen receptors is enormous. Lymphocytes which encounter antigens that happen to match their receptors, are selected in a Darwinian manner. This is the basis of immunization - somatic DNA recombination is the reason why we are able to make antibodies against such an enormous number of pathogens. The fact that the receptors aren't "hard-coded" makes this a very flexible system, which can adapt to new threats. To my knowledge, it is the only known example of somatic DNA recombination in vertebrates. --NorwegianBlue ^talk 20:56, 1 February 2007 (UTC)

Only known example, except of course somatic mutations that lead to cancer. --NorwegianBlue ^talk 21:03, 1 February 2007 (UTC)

In your comment NorwegianBlue,"The rearrangement occurs in a random fashion, and because various fragments are involved, each of which comes in a large number of variants, combinatorics assures that the number of combinations is formidable", are you saying as our DNA changes during maturation for immunizations against pathogens, this possibly can affect hair texture, iris color, etc?I also know of an African-American person who also experienced the same issue as well...

No. This process only applies to the genes coding for the T cell receptor and the B cell receptor (immunoglobulin), and "maturation" refers to the maturation of the individual cell. --NorwegianBlue ^talk 21:03, 1 February 2007 (UTC)

Think of your hair changes similar to how your body changes when you go through puberty. When you hit puberty, you grow facial hair, get bigger & stronger & grow an adam's apple etc. This is not your DNA changing, but instead hormones & internal changes stirred by chemicals. Your body can change drastically without warning. Keep in mind however, that indeed DNA can affect whether we do have curly or straight hair, but changing between the two isn't unheard of either. Many children may have curly or straight hair in childhood & then have the opposite later in life. When babies are born, they may have a different eye colour to later on in life & so on & so on. Your DNA does not change unless you're one of the X men. Hope this explains it easily... Spawn Man 21:45, 1 February 2007 (UTC)

And if you're interested in whats going on on the molecular, level, you might want to read the article regulation of gene expression. --NorwegianBlue ^talk 08:45, 2 February 2007 (UTC)

I also experience this. When I was little, I had curly, thick blonde hair. Later my hair became really straight and black, and now my hair is this dark brown, but it's really curly and somewhat thick. All this happened in 16 years of my existence. I have a question, if it's not possible for your genes to change, where does evolution happen? Surely your genes have to change. ► Adriaan90 ( Talk ♥ Contribs ) ♪♫ 13:30, 5 February 2007 (UTC)

There are in fact mutations and genetic recombinations, and even DNA repair, but there are no deliberate, routine, permanent changes to DNA made by any organism. (The result would be very hard to do safely, after all.) Evolution is a result of the accumulated random changes to DNA inherited by offspring. See, however, the current field of genetics research dealing with promoters and company, which do not modify DNA but have much the same effect by dynamically affecting how it is used. --Tardis 19:15, 5 February 2007 (UTC)

Although your DNA is unlikely to have changed much since you were born, your body isn't. You grow in size and weight, and add new bits and pieces with puberty. An organism is very mutable: changes can be programmed in your dna; and it can be very hard to pinpoint what triggers certain changes. But it's not uncommon or a result of mutation (save for very VERY rare cases). Pedro Almada, GMT, 15:06, September 16, 2007

If you tied a rope around the moon and let the other end hang down onto the surface of the earth...

1)When the moon moved, would the rope drag across the surface of the earth, and if so how fast? 2)And if not, would it go out into space and trail behind the moon or what would it do? The gravity field of the earth and the moon are significantly less than the amount of empty space in between the earth and the moon. 3)If the answer to the first question is no, could you hold onto the rope as it pulled you up into the sky? 4)How much weight would it take to keep the rope vertical to the earth? 5)Would that amount of weight cause the moon to stop moving and come crashing down onto the earth?

This will be a big help for one of the questions on my thirty-problem physics project, thanks! Xhin 16:47, 1 February 2007 (UTC)

(numbered the questions to make responses easier). During a single night, the earth's rotation makes the moon appear to move across the sky. Per Moon the Moon makes one complete orbit about the Earth every 27.3 days. The nearest point to the moon on the earth's surface makes a revolution every day, with adjustment for the moons 27.3 day cycle. What does that suggest about the rope staying at one point? Per Earth the planet's mean circumference is 40,041.47 km, and its sidereal rotation period is 0.997 258 d (23.934 h). Earth's rotation velocity at the equator is 465.11 m/s or 1040 miles per hour, which has to be adjusted plus or minus for the moon's travel around the earth.The question implies that the rope starts on the earth's surface. The statement "The gravity field of the earth and the moon are significantly less than the amount of empty space in between the earth and the moon." makes a meaningless comparison between gravity and space. How can gravity be less THAN space. Did the question originally say IN space? I suggest the hypothetical rope would have to be extremely strong and perhaps fireproof. I suggest that no amount of weight could keep it absolutely vertical to the earth, but the deflection from passage through the atmosphere would be a difficult calculation depending on air resistance, which would depend on the diameter and surface of the rope, and more complex because it would change with altitude. Edison 17:31, 1 February 2007 (UTC)

The question would be interesting if rephrased for a sitution where both bodies are tidally locked with respect to each other (eg. Pluto and Charon). What stresses would be suffered by a space elevator linking these two bodies? Carcharoth 18:01, 1 February 2007 (UTC)

You should note the difference between the apogee and perigee of the moon's orbit.—eric 18:12, 1 February 2007 (UTC)

Well I've come up with a simple answer to your question. All the roads in New Zealand, lined back to back, would make it 3 quarters of the way to the moon. Now all you have to do is measure all the roads in New Zealand & then do the math. ;) Spawn Man 21:49, 1 February 2007 (UTC). P.S. The rope might catch on a rock & send the moon crashing down in the Atlantic, so be sure you use duel fibre twine... ;)

To question 1, I think yes. The rope would be close to vertical most of the way, but once it hits the Earth's atmosphere, the atmospheric drag will push it forward (since the Earth rotates faster than the moon orbits), so it will be slanted at an angle near the surface of the Earth. To question 4 (if I understand what you mean), that is impossible, because the atmospheric drag pushes the rope forwards, and if were vertical, there would be no force to oppose it going the other way. --Spoon! 23:55, 1 February 2007 (UTC)

Why Don't They Send Hubble's Twin in Orbit?

When they constructed the Hubble telescope two decades ago, all key components were manufactured in pairs (in case one breaks down, the redundant component is available right away). Now that the one currently in operation is approaching its end of life--and that another shuttle repair mission will cost a fortune--why don't they just put all the spare parts together and launch the thing up there? The twin may not be the latest technology, but it sure could be a cheaper way to get a new telescope in orbit, serving science for the next two decades.--JLdesAlpins 17:23, 1 February 2007 (UTC)

Is there evidence they made a second mirror? At the time of its making, there was an article about how expensive it was, and that it was the best mirror ever built. Later it turned out they had totally botched the fabrication and testing and the thing had to have corrective lenses added. Have some of the spares been used on the repair missions? An unanswered question is how similar the general optics of spy satellites are to those of Hubble. They are supposed to have amazing resolution, but would lack some of the aiming ability and some of the special astronomical optics. Edison 17:38, 1 February 2007 (UTC)

One of the largest differences between an earth-observing satellite and the Hubble is the amount of light collection area and maybe to a lesser extent the ability to keep attitude very precisely.Images like the Hubble Deep Field require an extremely long exposure time, even with the Hubble's large mirror.Images like [1] also show what vistas large amounts of light gathering area can give you.Like spy satellites, you or I can easily see things on Earth because they're illuminated so well, could never see anything like that with our pair of 1x 1-cm refractors. Atropos235 18:03, 1 February 2007 (UTC)

See Hubble Space Telescope#Optical Telescope Assembly (OTA) for information about the second mirror. --cesarb 18:30, 1 February 2007 (UTC)

Hubble was designed to be orbited in the carbo bay of the space shuttle.Given that you'd have to launch a shuttle either way, it is unlikely that there would be much cost savings.Dragons flight 17:42, 1 February 2007 (UTC)

Lets not forget the cost to acctually form the second hubble. putting the spare parts together will still require extreamly skilled scientist to put it together and many months to do it right Maverick423 17:51, 1 February 2007 (UTC)

And lets not forget, the spare parts were there in case something goes wrong, so imagine something went wrong while assembling the spare parts, they'd have no redundancy.Vespine 21:32, 1 February 2007 (UTC)

Hubble's "dubble"? Clarityfiend 01:20, 2 February 2007 (UTC)

OK, suppose that everything on Hubble was duplicated - Hubble has been serviced a couple of times since launch - might some of those duplicate "spares" have been used up in servicing it? Richard B 01:31, 2 February 2007 (UTC)

I think it's probably an engineering exaggeration to say "everything" was doubled; furthermore, the likelihood that all parts are carefully cataloged, stored in one warehouse, with blueprints and assembly instructions is virtually zero.Significant engineering effort would be needed; and even the original engineers probably don't even remember all of the design properties.It is probably easier and cheaper to start from scratch.After all, the most expensive part of spaceflight systems is very rarely the actual components costs. Nimur 08:29, 2 February 2007 (UTC)

Narcotics

Is there any type of narcotic drugs that include iodine atoms in the molecule? TERdON 18:07, 1 February 2007 (UTC)

The simple answer is yes - but they are not common. Iodine (and also other halogens chlorine, bromine and fluorine) is sometimes incorporated into the basic drug structure - one of the main reasons this is done is that the resultant compound is easier to absorb through the gut walls as it is more 'fatty'.

(also Iodinated and brominated 'ecstacy' derivatives are found often enough to be called common, I'm not sure that amphetamines are classed as narcotics though.)

I don't have enough knowledge to say if there are any drugs of this type in common use.87.102.77.95 19:23, 1 February 2007 (UTC)

In Sweden, no doubt amphetamine is illegal, I suppose the same holds true of its derivates. Thanks for the answer! :) TERdON 20:18, 1 February 2007 (UTC)

I don't think amphetamine is a narcotic (narcotics are derivatives of opium), but perhaps you meant psychoactive drug? − Twas Now ( talk • contribs • e-mail ) 22:13, 1 February 2007 (UTC)

I didn't mean they were narcotics by the scientific definition, but by the Swedish legal definition, which includes all kinds of addictive drugs that aren't, technically, narcotics. TERdON 22:18, 1 February 2007 (UTC)

Yes, "crack," but it's not in the narcotic.Instead it's part of the precursors, see Iodine in Methamphetamine production.As part of the "war on drugs," some states in the USA require that iodine suppliers record and retain customer information on anyone buying iodine. --Wjbeaty 20:42, 1 February 2007 (UTC)

Source

Is their there enough kinetic energy in a human body to move an object?—Preceding unsigned comment added by 71.201.233.107 (talk • contribs)

People move things every day - I'm not sure what else you could be asking? please explain..87.102.77.95 19:15, 1 February 2007 (UTC)

Do you know what kinetic energy is?It's the energy of a mass in motion.One way to tell that an object in motion has kinetic energy is to watch what happens when the object hits another object: in a collision, one moving object can impart kinetic energy to the collided-with object, causing the collided-with object to move as well.Does this answer your question? --Steve Summit (talk) 19:19, 1 February 2007 (UTC)

are you trying to talk about telekinetic energy? which is more of a phycic power then anything. Maverick423 21:09, 1 February 2007 (UTC)

See Psychokinesis. I would have to answer "No, there is not enough psychokinetic/telekinetic energy in a human body to move anything." But I have an open mind and would be ready to be proven wrong. There are many ways to fake it or to think it is observed in poorly controlled experiments. Edison 21:30, 1 February 2007 (UTC)

There's often just enough to move money from a believer's wallet/purse to the claimant's. Spooky! Clarityfiend 21:53, 1 February 2007 (UTC)

It might just be that things that can be moved like this are too small to see:)Hidden secret 7 20:47, 3 February 2007 (UTC)

To move an object with the kinetic energy of a human, you would need to have the human collide with the object.Imagine body-slamming a box.Then, your kinetic energy would (partially) transfer and the box would jolt forward.Perhaps you mean potential energy which may be stored in the muscles in chemical form (adenosine triphosphate)?This can be converted into kinetic energy, (probably also generating thermal energy and other forms...) allowing the muscle to move an object. Nimur 08:32, 2 February 2007 (UTC)

Hah.I'm now having hilarious visions of ragdoll-physics style "human collisions" to test the inelasticity of collisions.Efficient transfer of kinetic energy from the human to the object is almost as much fun as inefficient transfer. Nimur 08:34, 2 February 2007 (UTC)

High density polyethylene

Hello, does anyone know of a supplier for blocks of high density polyethylene.I'm looking for a small cube of the stuff that I can mill down a little bit.

Try McMaster-Carr. anonymous6494 20:55, 1 February 2007 (UTC)

Isnt polyethylene always the same density? --Light current 01:36, 2 February 2007 (UTC)

No. See HDPE vs LDPE. DMacks 02:46, 2 February 2007 (UTC)

Water on Mars

is there really water in Mars?–––Thanks

There is no doubt about the presence of water on Mars. A more intriguing question is whether or not there is liquid water on Mars, and recent evidence has been pointing towards a positive answer. — Kieff | Talk 00:29, 2 February 2007 (UTC)

Lava and Magma

Which is thinner, magma or lava?

same stuff I thought!--Light current 01:32, 2 February 2007 (UTC)

Well according to Chloe Talbot from The Simpsons, magma is the word for lava when it's underground. Which would mean that lava would be more viscous, but magma would be denser. Anchoress 01:42, 2 February 2007 (UTC)

No no Yes. Lava is magma when its under ground.When its erupted its lava. Pumice--Light current 02:28, 2 February 2007 (UTC)

That's what Anchoress said. =) Chickenflicker---♣ 04:33, 2 February 2007 (UTC)

Quire rite sorry. It was the Simpsons who put me off.8-)--Light current 11:45, 2 February 2007 (UTC)

If it had to be one or the other, it would be lava; but not by much, I would imagine. As the molten rock comes closer to the surface it experiences less pressure and presumably expands, making it less dense or "thinner". I'm not sure, however, the degree to which it would expand, or if that would be significant to appropriately label it "thinner". BenC7 07:22, 2 February 2007 (UTC)

If lava can be approximated as an uncompressable fluid, the pressure change would have little effect on the density.One thing that does significantly affect density is silica content.Hawaiian volcano lava is quite different from, say, Mount Saint Helens (which has more silica, is more dense, and thus exploded violently!)Hawaiian lava flows gracefully with much less exploding. Nimur 08:37, 2 February 2007 (UTC)

(comment) doesn't the explosiveness of magma relate to the amount of dissolved gas in it (eg water) - that is released when the pressure vessel that is the inner volcano is opened..(or does silica rich magma have greater ability to hold gases???)87.102.4.6 11:55, 2 February 2007 (UTC)

I too would expect lava to be thinner thicker (less more viscous) than magma since it is cooler. I don't know how pressure affects viscosity. Reading both articles it explains that the viscosity depends on the composition - so there may not be a definative answer.87.102.4.6 10:33, 2 February 2007 (UTC)

Both lava and magma is made of all types of substances, and are all different temperatures. [Mαc Δαvιs] X (How's my driving?) ❖ 18:09, 2 February 2007 (UTC)

I would have expected lava to be more viscous as it is cooler, since this would mean less kinetic energy for each molecule, and therefore less energy to move them apart:)Hidden secret 7 20:50, 3 February 2007 (UTC)

Unlike gases, there is no "ideal law" for fluids, let alone an accurate one. Non-ideal effects will dominate what factors determine density. Nimur 01:08, 4 February 2007 (UTC)