Wikipedia:Reference desk/Archives/Science/2012 August 11

Welcome to the Wikipedia Science Reference Desk Archives
The page you are currently viewing is an archive page. While you can leave answers for any questions shown below, please ask new questions on one of the current reference desk pages.

August 11

Hydroponic Corn

can or is corn or soy beans being grown in hydroponics ? — Preceding unsigned comment added by Idontbeliveit100 (talk • contribs) 00:23, 11 August 2012 (UTC)

Yes, as a quick Google search for hydroponic maize or hydroponic soy will quickly reveal. Tonywalton ^Talk 00:56, 11 August 2012 (UTC)

I find it hard to believe that can corn is grown hydroponically. A link would be nice. μηδείς (talk) 04:56, 11 August 2012 (UTC)

Oh, you were making fun of his oriental Engrish! nvm-- OBSIDIAN†SOUL 07:13, 11 August 2012 (UTC)

Almost any plant that grows on soil can be grown with hydroponics, it's the space that's the problem-- OBSIDIAN†SOUL 07:08, 11 August 2012 (UTC)

However, it's not always practical to do so. In the case of corn (maize), only a tiny portion of the plant is edible, and that doesn't sell for much, so it's probably not financially viable. StuRat (talk) 07:39, 11 August 2012 (UTC)

The most widely grown hydroponic crops are cucumbers, tomatoes, and peppers. There are also some who grow eggplant, lettuce, pole beans, strawberries, and other minor crops. While it is possible to grow corn or soybeans hydroponically, the yield increase, and the initial price of corn is too low to make it economically wise. 65.95.22.16 (talk) 12:54, 11 August 2012 (UTC)

In terms of value, the most important hydroponic crop is almost certainly cannabis. It is a major cash crop in California and Queensland. 203.27.72.5 (talk) 20:19, 12 August 2012 (UTC)

Portable train derailer

I was recently watching the film Unstoppable and I was a bit sceptical of the scene where the company tries to derail the train with an emergency portable derailer. In the film, some characters express doubt that it will work with a train as large and travelling as fast as CSX 8888. They turn out to be correct, as the train busts through. This film is based on a true story, and according to CSX 8888 incident, this scene is more or less accurate. If they were already willing to deal with the massive damage caused by derailing a speeding freight train with dangerous cargo, and there were prior doubts as to whether the derailer would work, why didn't they just rip up a few feet of track, rather than use the derailer? A stick of gelly would have done the job in 2 400ths of a second, so time probaby wasn't the issue. 112.215.36.179 (talk) 04:49, 11 August 2012 (UTC)

I don't know about the movie, but the real-life incident lasted two hours, according to our article. I suspect it might take a bit longer than that to get hold of "gelly" and figure out what to do with it. (Of course there are many other ways to derail a train.) Looie496 (talk) 07:03, 11 August 2012 (UTC)

Agreed. Time would be the problem. Removing rails takes equipment and men, and getting that all to the site takes time, and then it takes more time to do the work. I'd think parking a locomotive engine on the tracks might be the quickest way to derail a train, if you don't mind destroying it, along with the train. StuRat (talk) 07:35, 11 August 2012 (UTC)

How do you know that section of the movie mirrors real life? While it appears true the derailer did not work, this doesn't mean anyone involved in deciding or placing the device thought it it wouldn't work. Of course even if someone did think that, it does not mean they would have thought of proposing to blow up the train track. Given the time frames involved it would hardly be surprising if by the time it came to placing the thing, acquiring and using some sort of explosive would be 'difficult' at best, as Looie496 said you're perhaps overestimating how easy it would be to acquire and use particularly given the bureaucracy that I expect would be involved. Nil Einne (talk) 07:42, 11 August 2012 (UTC)

Nil, you appear to have suffered a seizure while typing that last sentence. Shall we call the paramedics for you ? StuRat (talk) 07:49, 11 August 2012 (UTC)

Apologies, typing on a mobile phone is not fun. I've since modified/corrected any errors in my above comment. Nil Einne (talk) 09:39, 11 August 2012 (UTC)

They had enough time to get the derailer there and install it, and also enough time to line up cops to shoot at some button. An oxytorch or even angle grinder could have made the tracks unusable in a minute, sooner with a few workers helping to destroy it. I don't know if anyone expressed doubt in reality, but I would think that the derailer has some sort of rating for weight and speed of the derailed train that might give some idea that it wasn't going to work. How common are these derailer thing anyway? I doubt they're the kind of thing you'd have lying around all over the place. You could also have quickly welded some scap to the track to make it unpassable. 112.215.36.177 (talk) 08:02, 11 August 2012 (UTC)

I doubt that any "derailer" actually exists.(I see that they do exist, but for a purpose other than in the movie.) They would need thousands of them positioned all over the nation to have any hope of having them where needed, and there would be more of a risk of "the bad guys" using one than them being used by "the good guys". The line of cops shooting at a button is complete silliness too. Welding isn't all that quick, again considering the time needed to get the equipment and a welder. StuRat (talk) 09:07, 11 August 2012 (UTC)

Derails certainly do exist, and the fact they sourced and installed onein time to watch it not work illustrates my point that they had time to do something a bit more sure. Weldin equipment is prolific as are angle grinders. Welding isn't quick if you are trying to do a good job of it, but this is making a mess on purpose. 112.215.36.171 (talk) 09:28, 11 August 2012 (UTC)

(EC) Did either of you bother to read the Derail article which is linked from the article on the incident and the one on the movie (which the OP themselves linked to when starting this thread)? These things do exist and from the sound of it, they aren't uncommon, evidentally frequently (always?) used when a crew is working on the line so I presume likely something carried by most work crews. I have no idea if they usually have ratings, but again, I think the OP is overestimating how much analysis went in to what was seemingly one desperate idea sometime during the 2 hour stretch. Nil Einne (talk) 09:39, 11 August 2012 (UTC)

Obviously I have, since I linked to it. I'm not overestimating the thought, I'm asking if they could have done it better. The derailers are used in the yards, not at random points along the line where the attempted derailing was done, so they probably would have needed travel a fair way to get one. An oxytorch, tig or mig welder, or angle grinder was probably handy at that same yard and using it would probably have taken just as long as bolting on the derailer. 112.215.36.171 (talk) 09:52, 11 August 2012 (UTC)

As I mentioned, I got an EC, and in any case, from my indenting it should be clear I was replying to StuRat's reply to your post (not your reply to StuRat's reply) so effectively you didn't link to derail until after my post. (You did link to the other articles, but plenty of people don't seem to read the articles they link to let alone the relevent articles linked to in them.) If you read the article, I'm confused why you say they are used only in yards as our article doesn't suggest that in any way, it fact as I said it seems to imply portable derailers are regularly used by work crews. There are some types of derails which are often installed near yards (and other places), but these aren't generally portable ones for obvious reasons. Incidentally, how well do you actually know precisely where the derail was done and how far it was from places where a portable derail may have been available (like wherever a workcrew stores their equipment)? I presume we're talking about the real life situation since it's pretty silly to discuss what was presented at the movie [1] if we are interested in the facts of the real life situation. P.S. Both [2] [3] are supposed to provide protection to track crews anywhere. Nil Einne (talk) 16:56, 12 August 2012 (UTC)

They are used like lock out tags. They render the locomotic unable to move while being worked on, so they're obviously going to be kept with the rest of the tools, etc. I don't know much about the location, but I don't need to for what I'm saying. The derailers form part of the workers kit, so it would be found with the other tools used at rail yards. When they went to get the derailer, surely they could have gotten any one of those things I suggested instead. Anyway, it's all a moot point since you already provided a reference that a contingency along the lines I described was in place. 149.135.147.2 (talk) 18:10, 12 August 2012 (UTC)

Long time later, I avoided this discussion once it became clear it was started on false premises. Anyway surely it depends precisely where the portable derailer came from? It may have been there was a work crew nearby that had one, but not necessarily the tools you refer to. And I don't see any particularly reason to assume a portable derailer is always going to be stored with such tools as the precise tools may depend on the job. For example a crew who mostly works on inspecting the line may have a portable derailer, but not the tools you refer to Ultimately I stick by my main point, without knowing precisely where the derailer came from and precisely how far it was from where it was used and other such things, it's just silly to make assumption about what else would or would not have been available. Nil Einne (talk) 16:17, 20 September 2013 (UTC)

To destroy railway lines in wars explosives just get thrown all over the lines, often from the air. There's no need for precise placement to be effective, but thinking about what you're doimg might help. If you stuck a grenade under the rail you should do a bit of damage by bending it upward. If you could get it at a join it could do even better.112.215.36.171 (talk) 09:45, 11 August 2012 (UTC)

And surely SWAT, the National Guard, the Army or other fast response unit could turn up a few grenades or better in a hurry. Even a gun store could have donated a cache of gunpowder. A chain attached to the track and pulled with a pickup might have been sufficient to distort the track enough. 112.215.36.179 (talk) 08:15, 11 August 2012 (UTC)

To attach a chain you'd need to drill a hole through the rail. This would take time, too. (If you just placed it under a tie, the tie would likely just break.) Good luck getting grenades from the Army in a hurry. Getting gunpowder, placing it properly, laying a fuse, etc., again takes time and expertise. StuRat (talk) 09:07, 11 August 2012 (UTC)

You can loop a chain or braided wire underneath the metal rail between the sleepers. You only need to move it an inch or so with a winch to make the rail unpassable. 112.215.36.171 (talk) 09:38, 11 August 2012 (UTC)

From a quick search, this whole thread may have been founded on false premises. According to [4] they may have been taking up rails further down the line. (It also suggests some people weren't surprised by the failure of the portable derailer given the speeds involved, but again this doesn't mean does actually involved had the same thoughts. It's somewhat unclear to me the expertise of those involved in making the decision and in placing the derailer.) Nil Einne (talk) 09:48, 11 August 2012 (UTC)

Thanks for that! 112.215.36.171 (talk) 09:58, 11 August 2012 (UTC)

Resolved

That link is well worth reading - one point I take from it is that the runaway was at eighth throttle and had its brakes on, but burned through them; also I saw something about it dragging equipment(?). So I doubt anyone could have predicted the speed at which it would hit the derail with any confidence. Wnt (talk) 12:12, 11 August 2012 (UTC)

P.S. I forgot to mention that for all the experts who said it probably wouldn't work, it wouldn't be surprising if there were also experts who said it probably would. The nature of such things is that after one set of experts are proven right, the other set tend to slink away with everyone treating it as a clear cut situation at the time if only you'd listened to the experts. Nil Einne (talk) 17:22, 12 August 2012 (UTC)

There are also Catch points, but of course whether there actually was one they could have directed the runaway train to is another matter. Vespine (talk) 23:31, 12 August 2012 (UTC)

As I understand it, no need for anyone to slink away. Derailing a runaway train at a controlled location was apparently standard procedure - and if you're trying to derail a train, what's the worst that can happen? To put it another way, imagine you're the expert who said not to try it, telling the people of some small town whose little business district and half the customers therein have just been horribly burned with liquid phenol, "well, we were pretty sure it wouldn't work, so we didn't try." Wnt (talk) 14:19, 13 August 2012 (UTC)

I don't think anyone was suggesting to not try to derail it; just to derail it a different way. 203.27.72.5 (talk) 21:54, 13 August 2012 (UTC)

There is more than one type of derailment accident. One caused by a derail or other minor obstacle is likely to simply lift the train off the low-friction rails and deposit it, still upright, on the high-friction ballast, with the rails guiding it a mostly-straight line (most derailments are of this sort). One caused by blowing up the tracks, cutting out sections, ripping up rails, or other major track damage will tend to cause the train to overturn, and when the train is carrying hazardous materials, you really don't want that to happen. --Carnildo (talk) 01:03, 15 August 2012 (UTC)

Wnt, a long time later but I think you missed my point. The original premise of this question was that it was silly to use the derailer since it was clear it wouldn't work since we now hear that's what the experts said. However the reality of the situation could easily be that there were at least some percentage who said it might or would work. Of course once it didn't work, we generally only hear about those who said it wouldn't work so it sounds like it was clear cut at the time when often it's not. The same can be said for pretty much anything about this whole situation or so many other situations. (Remembering as well we were talking about a very short time frame and a likely chaotic and panicked situation where it's likely no one would have wanted to stop something which later people may say may have worked even if they also wouldn't want to be responsible for something which didn't work and people are going to say will never have worked and wasted time and distracted from potentially more fruitful efforts.) Nil Einne (talk) 16:17, 20 September 2013 (UTC)

Microscope on Mars

Why has no Martian lander brought along a microscope? Since all but the smallest Earth organisms can be seen under a light microscope, and images of moving microbes is indisputable evidence for life, it would seem a much more logical choice than the astrobiological equipment Viking 1 and 2 brought along. --140.180.5.169 (talk) 06:35, 11 August 2012 (UTC)

Your premise is wrong. Spirit, Opportunity, and the Phoenix lander have all had microscopes. Unfortunately they haven't managed to get any moving microbes into them. Looie496 (talk) 06:58, 11 August 2012 (UTC)

I mean a high-powered biological microscope. Spirit and Opportunity's MI had a resolution of 30um/pixel, while Phoenix's limit was 16um/pixel. Curiosity's MAHLI does slightly better than 14um/pixel. These microscopes were designed to look at geological features, not life. Earth bacteria are typically a few micrometers in diameter, far below the resolution of even MAHLI, and there's no reason to expect potential Martian microbes to be much smaller. --140.180.5.169 (talk) 07:22, 11 August 2012 (UTC)

There is also no reason to expect finding microbes on the surface of Mars, just at a random place. The Curiosity rover will actually try to reveal whether Mars was able to support life. OsmanRF34 (talk) 12:43, 11 August 2012 (UTC)

Actually MAHLI would be able to image growing colonies of microbes, even if not typical individual Earthian cells. Nobody expects enough water to find mobile protozoa, just spore colonies if anything, and only a tiny minority of scientists have their hopes up. MAHLI might turn out to be fairly important in this regard because the analytical biochemistry instruments are likely to have a serious Teflon contamination problem which wasn't caught until after the MSL was launched. Also, I think the 14 micron/pixel number is a worst case figure assuming that there was more vibration and dust damage than there may be. With luck it will be far better. 75.166.207.214 (talk) 01:10, 12 August 2012 (UTC)

They had to be extremely conservative with what they put on the rover due to concerns about weight. Including a highly sensitive microscope, as well as any protective equipment to make sure it survived the trip, would mean that something else had to be left out. Since Curiosity is not digging very deep in the soil, and the surface of Mars certainly seems inhospitable, I imagine it would be extremely unlikely to come across anything living, making such a weight-expensive piece of equipment kind of a waste. Someguy1221 (talk) 01:18, 12 August 2012 (UTC)

To built a microscope capable to scan sand for microscopes is extremly chalenging. The small focal point the very uneven surface and so on. The focalpoint is very small and to have microbe init is highly unlikely for sand. To scan 1cm^2 for microbes takes ages.--Stone (talk) 18:43, 14 August 2012 (UTC)

Extinct domesticated animals

The extant African wild dog

Has any domesticated species gone extinct? I know that some sub-species are now extinct, and there are many others to come, but don't know of any complete species which got lost. OsmanRF34 (talk) 12:30, 11 August 2012 (UTC)

Apparently none. Ironically, domestication probably saved a lot of animals. Though with the steep price of genetic erosion and the extinction of the remaining wild populations, which renders them less adaptable. A lot of them would probably go extinct very quickly if they lose all their economic value to us and are discarded. Anyway, I found two possibilities:

• The North African elephant which were used as war elephants by Carthage, which might be a separate species or a subspecies of the African bush elephant.
• The Balearic Islands cave goat, the remains of which discovered by archeologists show attempts at domesticating them by early humans, though it ultimately did not succeed.

-- OBSIDIAN†SOUL 14:26, 11 August 2012 (UTC)

According to our Aurochs article, the species was domesticated twice. --TammyMoet (talk) 15:32, 11 August 2012 (UTC)

Although the distinction between species and sub-species is not always straightforward, I would say that the aurochs, being considered the direct ancestor of modern cattle, is to a modern cow as a wolf is to a dog, i.e. part of the same species. The binomial name of both is identical: 'Bos primigenius'. - Lindert (talk) 15:47, 11 August 2012 (UTC)

Well yes I agree with you, and maybe the article needs modifying, but from what it says, the aurochs was domesticated twice and is now extinct as a species, which makes it a correct answer to the question. I'm as dubious as you are, but I don't have the background knowledge to argue here. --TammyMoet (talk) 17:49, 11 August 2012 (UTC)

Except it wasn't a different species in the sense that it would be able to produce fertile offspring with most of today's wild or domestic cattle breeds. Similarly, one of the ancestor clades from which domestic sheep were apparently hybridized is no longer extant[5] but that hardly counts as a different species. The African wild dog is gone but nobody knows if it was the same species as the domestic dog (PMID 8020615) and being wild it doesn't apply. I have to agree with Obsidian Soul: getting domesticated is apparently an airtight advantage against disease, environmental pressure, and predators. 75.166.207.214 (talk) 01:31, 12 August 2012 (UTC)

The African wild dog is neither extinct nor the same genus as Canis familiaris. μηδείς (talk) 01:55, 12 August 2012 (UTC)

Oops, that's right. I was reading "extinct populations" as "extinct species," sorry. Also, I'm not entirely sure I'm reading that sheep paper correctly. The wild ancestor involved may or may not be extinct, but in any case it certainly wasn't a different species. (Even though every variety of sheep seems to have a different number of chromosomes...?) 75.166.207.214 (talk) 03:16, 12 August 2012 (UTC)

Yes, none of the four species named in the abstract you gave is extinct. But Lycaon pictus has always been on of my favorites for both its appearance and its binomial. Rather a vicious little bugger though. μηδείς (talk) 03:23, 12 August 2012 (UTC)

The dog is correctly Canis lupus familiaris, as it's a subspecies of the gray wolf (Canis lupus). The problem is an old one, since early taxonomists gave different names to domesticated species from their wild ancestors, mostly because they didn't know they were their ancestors (genetics wasn't even a possibility then). Even now some biologists are still unclear as to the ancestors of some domesticated species, as some are actually hybrids as well (e.g. a lot of modern banana cultivars are actually hybrids of two wild species).

I think 75.166.207.214 meant "wouldn't". Modern zebu and European cattle are descendants of the aurochs and have most likely not acquired reproductive isolation at all (i.e. if aurochs were still extant, they could produce perfectly fertile offspring with modern cattle), so they're technically not extinct. Compare with the horse (Equus ferus caballus) and the wild horse (Equus ferus, of which at least one subspecies is already extinct); as well as the domestic cat (Felis sylvestris catus) and the wildcat (Felis sylvestris). Some taxonomists prefer to separate these as different species (mostly tradition or just because they think they're different enough to justify the separation).-- OBSIDIAN†SOUL 05:47, 12 August 2012 (UTC)

monopole magnets

Whether it is possible to make mono pole or sing pole permanent magents?

Has anybody made it or invented it?

Who has invented it?

When was it invented?

Who is holding patents for it? — Preceding unsigned comment added by 27.0.62.41 (talk) 19:22, 11 August 2012 (UTC)

I fixed title and formatting. StuRat (talk) 19:26, 11 August 2012 (UTC)

As our magnetic monopole article says, it's a purely hypothetical object, meaning it has never been made, nobody holds the patent, etc. According to some theories, they should exist in nature, as subatomic particles, and experiments have been done to attempt to detect them, but not has conclusively proven their existence yet. StuRat (talk) 19:29, 11 August 2012 (UTC)

We can be sure that monopoles do exist, in the sense that you can make them, not that they actually exist somewhere in the universe. Monopoles limit the maximum possible magnetic field strength that can be sustained. As explained here, string theory predicts a maximum field strength of the order of 10^47 to 10^49 Tesla, above which you would get monopole anti-monopole pair production which would then degrade the magnetic field. Count Iblis (talk) 20:45, 11 August 2012 (UTC)

By "you can make them" I presume you mean in the strictly theoretical sense that such hypothetical particles are not known to be inconsistent with physical laws, not that anyone knows how to make one. 75.166.207.214 (talk) 02:41, 12 August 2012 (UTC)

Just take a bar magnet and cut it in half. Problem solved! Patent please $:-)$ Bubba73 ^{You talkin' to me?} 02:48, 12 August 2012 (UTC)

Emphasis added :p 75.166.207.214 (talk) 03:04, 12 August 2012 (UTC)

I would be surprised if Apple's patent lawyers weren't already trying to patent this. — Preceding unsigned comment added by 217.158.236.14 (talk) 13:10, 13 August 2012 (UTC)

Is my nose growing longer? Bubba73 ^{You talkin' to me?} 15:55, 12 August 2012 (UTC)

If you cut a wit in half, do you end up with a half-wit, or a twit? Plasmic Physics (talk) 02:12, 13 August 2012 (UTC)

Is it possible to make a monopole using a magnetar? 148.168.40.4 (talk) 14:08, 13 August 2012 (UTC)

As Count Iblis noted above, yes you could if the magnetar was ~10,000,000,000,000,000,000,000,000,000,000,000,000 times more powerful than those previously observed. 203.27.72.5 (talk) 21:49, 13 August 2012 (UTC)

Rubber Eraser

Where could i get large amounts of Kneedable Eraser for very cheap? I already Checked Dickblik — Preceding unsigned comment added by 205.142.178.36 (talk) 19:40, 11 August 2012 (UTC)

Have you tried Amazon, Ebay or TheArtShop? --TammyMoet (talk) 19:50, 11 August 2012 (UTC)

Our kneaded eraser article unfortunately doesn't address the question of the identity of the composition of the product, which may vary by brand. Bus stop (talk) 01:32, 12 August 2012 (UTC)

Did anyone ask that question? 112.215.36.181 (talk) 09:48, 12 August 2012 (UTC)

A way to search for the product is to know the identity of the product. "Kneedable Eraser" in its exact spelling is not even found at dickblick.com. I find lyra-kneadable-eraser as well as kneaded-rubber-erasers. The question is actually posed here as to "Whats a kneading eraser?" and one answer seems to be that a "kneading eraser" is "One that gets depressed and jealous when you use a different eraser." Bus stop (talk) 10:15, 12 August 2012 (UTC)

How much do you want? there is a difference between wanting a kilogram, a truckload or a shipload of the product.

I want 100 shipped to my house for very cheap nothing more than $30. can anyone make this happen and find it for me? — Preceding unsigned comment added by 205.142.178.36 (talk) 23:45, 12 August 2012 (UTC)

One thing to bear in mind is that they come in different sizes. Some measure 1-1/4" × 1-1/4" × 7/16". Others measure 1-1/4" × 3/4" × 1/4", 1-3/4" × 1-1/4" × 1/4", or 2-1/8" × 2-1/8" × 3/8". Bus stop (talk) 16:32, 13 August 2012 (UTC)

Reparative growth and spindle

1. What is the meaning of 'reparative growth'?
   
2. I, usually, find the term 'spindle shaped'. Can you provide me a picture of spindle? (Not homework) 223.176.135.81 (talk) 23:45, 11 August 2012 (UTC)

Actually, that's a misnomer. It refers not to the shape of a spindle, but to the yarn wrapped around it. Here's a good picture: [[6]]. And reparative growth is any growth associated with repairing damage, like the fussion that occurs between the two pieces of a broken bone, for example. Dominus Vobisdu (talk) 00:12, 12 August 2012 (UTC)