Wikipedia:Reference desk/Archives/Science/2012 July 4

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July 4

Pollination

How pollen get to the stigma? — Preceding unsigned comment added by 175.137.136.34 (talk) 00:39, 4 July 2012 (UTC)

Please read the article pollination. It should answer your question pretty thoroughly. Evanh2008 ^{(talk|contribs)} 00:43, 4 July 2012 (UTC)

Or watch Grease 2, in particular the biology lesson. Or just Google the lyrics. Mitch Ames (talk) 11:15, 4 July 2012 (UTC)

Oddly enough, that song isn't even the best reason to never watch that movie... Evanh2008 ^{(talk|contribs)} 11:30, 4 July 2012 (UTC)

Artificial Insemination for "Lonesome George"?

The recent death of the last Pinta Island tortoise, Lonesome George, resulted in the extinction of this sub-species of Galapagos tortoises [here]. Attempts to mate him with related species did not work, as Lonesome was not really interested. I am wondering why Artificial Insemination was not used, as it is in just about any species which have a commercial angle for humans.

Then again, I am not really sure how AI works (Same acronmy as Artificial Intelligence!). Is it just a case of masturbating the animal with electricity? If so, can I buy such a device? Maybe with tortoises, it would just take too long. Would they let him look at some piccies of really horny she-tortoises while they did it?

I've heard that men in comas have "donated" sperm via this procedure. It gives the term "manual work" a whole new dimension. Seriously, though, how DOES AI work, and could it have been used in Lonesome George's case? Coz if it could, we could all have these lovely creatures home as pets - there would be zillions of 'em! Myles325a (talk) 09:04, 4 July 2012 (UTC)

It is very difficult to masturbate reptiles. I hope they froze his testes before the spermatocytes died. 75.166.192.187 (talk) 09:55, 4 July 2012 (UTC)

You say it is very difficult but how exactly do you masturbate a reptile? SkyMachine ⁽⁺⁺⁾ 11:25, 4 July 2012 (UTC)

The question remains; once he's dead why not just operate to extract some semen? Or was he just too old to produce it?--Shantavira|^{feed me} 11:48, 4 July 2012 (UTC)

As all reptiles have their equivalent of a penis (their hemipenes) totally inside, and only extend it outside when sexually excited, and we humans don't look or smell like a sexy female reptile (and in most cases would have little idea what the species courtship procedure, if any, actually is), getting a male reptile excited would I think be just about impossible, let alone getting him to come...

Hey, we are the "Yes We Can" people, ain't we? We could derive some of that wonderful pheromone reptile fragrance, and rub it all over, and string some crocodile handbags on various parts of our anatomy or something. It's not that hard. Myles325a (talk) 04:35, 5 July 2012 (UTC)

...There may be some injectable homone method possible, but I doubt that it has been studied adequately, or of it has, you probably can't buy the hormone. Wickwack120.145.155.9 (talk) 12:02, 4 July 2012 (UTC)

Your premise is in any case incorrect. Lonesome George was "interested" and did mate with two female companions of a closely related sub-species, who laid (if I recall correctly) 3 clutches of eggs between them, but the eggs proved to be infertile. AI might well have had the same negative result. {The poster formerly known as 87.81.230.195} 84.21.143.150 (talk) 12:28, 4 July 2012 (UTC)

Now I am really wondering if the rangers and scientists at least bothered to take a flesh / sperm sample for future studies. Even if we can't clone Lonesome now, or use his sperm now, we might be able to do so in a few years time. Anyone know if this was done? Myles325a (talk) 04:35, 5 July 2012 (UTC)

• Yes you can - do electroejaculation on a turtle. [1] Wnt (talk) 15:51, 5 July 2012 (UTC)

OP myles325a back live! Ahh, I looked up that article, and it specifically notes procedure is used for "male mammals". There is no reference anywhere there that it has ever been used, or indeed could be used, on reptiles. Although now I see how it works in general. Electric dildo up the bum gives prostrate a good charge. Sounds awfully kinky, or am I just being immature about this? Presumably that is the raison d'etre for gay sex. Myles325a (talk) 05:06, 6 July 2012 (UTC)

• The soft approach, however, seems less productive. [2] Wnt (talk) 15:52, 5 July 2012 (UTC)

OP myles325a Back Live Part II. Sorry, did someone edit out summink here, or have I just had an attack of the obtusenesses. What is "the soft approach", and why does it seem "less productive"? Myles325a (talk) 05:06, 6 July 2012 (UTC)

• Figures. They were too cautious ever to do it. [3] Wnt (talk) 15:55, 5 July 2012 (UTC)

OP myles325a Back Live Part III: The Adventure Continues. Wtf! Am I getting the old-timers' disease? Too cautious to ever do what??!!Myles325a (talk) 05:06, 6 July 2012 (UTC)

Higgs boson

in this context what is the Golden Channel? Kittybrewster ☎ 09:08, 4 July 2012 (UTC)

The CMS Golden Channel is the pp→H→ZZ^(*)→4μ decay branch per [4]. 75.166.192.187 (talk) 09:50, 4 July 2012 (UTC)

(edit conflict) The Higgs boson cannot be detected directly because it decays too quickly. Therefore the various detection experiments actually look for the products that would result from one or more ways in which the Higgs boson could decay. Each of these decay "modes" is called a channel. Even if the right decay products with energies, directions etc. in the right range are observed, there is a chance that they could have come from some other interaction. So it may be difficult to separate the decay events that we are interested in (the "signal") from other random events that we are not interested in (the "background"). The best "channels" to search are the ones where there is most signal and least background, or which can be "cleaned" to reduce the background (all this terminology comes from signal processing); an especially good search channel is called a "golden" channel. The "golden" channel for Higgs boson detection is decay mode H -> ZZ* -> 4 leptons - see here for more details. Gandalf61 (talk) 10:00, 4 July 2012 (UTC)

apricots

Do apricots ripen on the tree or should theu be picked when not quite ripe? — Preceding unsigned comment added by 37.102.230.28 (talk) 14:21, 4 July 2012 (UTC)

Judging by what they sell in supermarkets, I would say they pick them before they ripen. 92.80.7.143 (talk) 14:22, 4 July 2012 (UTC)

Ideally the later you pick them the better, but the later you pick them, the harder they are to handle. It comes down to a tradeoff. The best test, for apricots and other types of stone fruit, is to sniff one. If it smells like an apricot, it will probably have good flavor. If it smells like nothing (the usual case, unfortunately), it will probably taste like nothing. Looie496 (talk) 15:30, 4 July 2012 (UTC)

Simple answer to the question - they WILL ripen on the tree. In my neighbourhood, that opens the risk of the local birds enjoying more of them than I do, but they are better fresh from the tree. HiLo48 (talk) 17:20, 4 July 2012 (UTC)

Slightly underripe is best for jam. A French friend made apricot jam for me and added slivered almonds soaked in brandy. Mmmmm. Itsmejudith (talk) 20:53, 4 July 2012 (UTC)

Are you sure that what you thought were almonds, weren't in fact the kernels from the apricot stones? I have a recipe for apricot jam which involves cracking the apricot stones, removing the kernels, soaking them in brandy and adding them to the jam before potting. --TammyMoet (talk) 09:39, 5 July 2012 (UTC)

Hmm. My understanding is that apricot kernels contain significant amounts of cyanide. Looie496 (talk) 16:14, 5 July 2012 (UTC)

Apricot kernel. 86.143.135.49 (talk) 21:41, 5 July 2012 (UTC)

Mixing old and new batteries

Resolved

1. All electronic devices discourage mixing old and new batteries. Can somebody please explain why?
2. I just modded my Wii sensor bar to USB powered. The sensor bar takes 7.5 volt from the Wii, and it refused to run with 5 volt from the USB 2.0 port. So I had to add a 1.2v battery and it ran fine. The battery is drained over time, I know, but the power from the USB port remains the same. The circumstance is very similar to mixing old and new batteries. Is it harmful to the battery and the device? FYI, the battery I use is rechargeable. I'm not sure if there is any difference between the rechargeable and non-rechargeable batteries, but my thought is that the USB port charges it when its capacity is running low.

-- Livy (talk) 15:20, 4 July 2012 (UTC)

With dry cells (carbon-zinc, alkaline, etc), the reason why you are advised not to mix old and new is because the stronger cells will reverse-charge the weaker cells. This takes the cells outside the design parameters of manaufacture and the cells may then leak corrosive substances, damaging the electronic device. With rechargeable cells, generally and sort of mis-match (age, type, size, etc) will run the risk of reverse charging the weaker units and this will damage them. Also, especially with dry cells, their internal resistance rises as they are discharged. The stronger cells must force current thru this resistance, which means you get less usable energy out of the good cells than you should. Putting a cell in series with the 5V supply of a USB port does not seem very wise, as again you are taking the port outside design parameters. When the computer/usb port is powered down, the cell will discharge back into the usb port and may damage it. A boost switchmode regulator should be used if you need to increase voltage. The USB port will NOT recharge a series connected cell - the cell, if connected so as to increase the voltage, is connected the wrong way round for recharging. Keit120.145.155.9 (talk) 15:46, 4 July 2012 (UTC)

I always unplug the sensor bar from the USB port after playing, before turning my computer off. Is there any other potential risk for the sensor bar, the battery, or the computer? -- Livy (talk) 19:16, 4 July 2012 (UTC)

Assuming you are using a dry cell, and you do disconnect before powering down, there is no additional risk provided that you never allow the cell to become flat. If it becomes flat, the reverse charging from the USB port may cause the cell to swell up, possibly preventing you from getting it out of the holder. If the cell/battery is a rechargeable, you run the risk of over-reverse-charging, which will certainly damage the cell and may cause venting of the electrolyte. While you may intend to always disconnect before turning your computer off, you may forget. Be aware that under certain configurations, USB ports may be depowered when the computer is in sleep mode. If the electronic device becomes shorted, the cell is now directly across the USB supply, and if a small cell, could in theory explode, though this is not very likely for common cell types (Li-ion excepted). Using a cell in this way is not very wise. Ratbone124.182.173.101 (talk) 01:20, 5 July 2012 (UTC)

I know it is not wise, but I suppose I do not have much of a choice. If I had not did it, I would have disassembled the sensor bar and removed some IR LEDs to make it working, but the Wii Remote accuracy would reduce. Currently I am using a rechargeable battery. Can you please explain the "over-reverse-charging" thing? I do not know much 'bout physics so you shouldn't need to go into technical details. I just want to know when it happens and how to avoid it. Thank you. -- Livy (talk) 03:57, 5 July 2012 (UTC)

There's 2 parts to this - reverse charging, and over charging. I'm an electronics engineer, not a battery chemist, but here's my understanding:-

First, reverse charging:- If you take a fully charged cell, it will provide a voltage across the terminals, with the correct polarity. As the cell is discharged, the voltage falls, slowly at first, then increasingly rapidly. For equipment functional purposes, and to avoid cell damage, industry considers cells "discharged" when the voltage drops to a certain level, well above zero. However, true 100% discharge can be considered to be when the voltage IS zero. If you keep on, after the zero volats point, forcing current thru the cell in the discharge direction (by means of an external voltage), the cell voltage will build up again, in reverse polarity. That is, instead of + at the +terminal, it goes negative. This is a "reverse charge". In some types of cell chemistry, any reverse charge will destroy the cell. It others it the cell remains chargeable in the correct direction, but its capacity will be reduced.

Over-charging: if you over-charge a battery, excess gas will be generated at each terminal. Rechargeable batteries incorporate recombination systems to re-absorb/re-cycle the gas under normal charging conditions. Overcharging is where the recombination system cannot cope with the excess gas. When the gas is not recombined, battery capacity is permanently reduced. So-called "sealed" rechargeable batteries have the electrode/plate dimensions and chemistry adjusted so that one electrode/plate gasses significantly first - this means that the recombination system only has to cope with one type of gas, which simplifies things and makes for better performance. If you reverse-charge it, the wrong size elecrode/plate generates the gas, so the recombination system cannot function as well. This means overcharging occurs far more readily in the reverse direction.

Ratbone58.170.162.104 (talk) 07:02, 5 July 2012 (UTC)

Thank you 2 for your help. Question resolved. However, any suggestion is always welcome. -- Livy (talk) 07:55, 5 July 2012 (UTC)

Independant existance of protons and neutrons in the nucleus

How correct?

The conventional conception of the nucleus of an atom pictures a group of protons and neutrons stuck together something like a cluster of grapes. (With the advanced proviso that due to quantum effects the nucleons don't have a precise location.) I'm wondering how accurate that picture is in reality. In the full QCD treatment, can you really separate things into four individual clusters of quarks, two each of uud and ddu? Or is it more like a sea of 12 quarks, six each of u and d? (Okay, quantum being what it is, I anticipate the answer to be "a little bit of both" - I'd appreciate what clarification you can give as to how things break down individual versus soup.) -- 71.35.99.136 (talk) 17:10, 4 July 2012 (UTC)

Yes, they are separate bunches. For example, if you collide energetic particles with a deuterium nucleus (i.e. one proton bound to one neutron) you can tell that the collisions are consistent with two bunches of three quarks each rather than a single mess of six quarks. Nucleons can be thought of as having a core of actual quarks and an outer shell of virtual pions. Binding between nucleons more or less occurs by overlapping their associated pion fields, so that the core quarks aren't directly overlapped. Dragons flight (talk) 17:59, 4 July 2012 (UTC)

Incidentally, if you want to know what a mess of quarks would look like without the bunches, then that basically describes a quark-gluon plasma, which can only form at very high energies. Dragons flight (talk) 18:02, 4 July 2012 (UTC)

Quantum field theory

Am I correctly interpreting this article? [5]

My interpretation is that a certain force is produced when a certain particle crosses its associated field. So for example a magnetic force is produced when an electron crosses the magnetic field. Is this correct? 176.250.196.132 (talk) 20:00, 4 July 2012 (UTC)

No, not really. What you're describing is basically a classical particle responding to a classical field. But quantum field theory is much more complicated than just being a matter of particles being subjected to a force when exposed to a field. For one thing, QFT is a probabilistic theory, instead of a deterministic one like a classical particle in a classical field. For another thing, in QFT, how many of each of the various types of particles involved there are in general changes during a QFT reaction. To understand QFT, you'll first need to understand quantum mechanics. Red Act (talk) 02:56, 5 July 2012 (UTC)

Higgs implications and hydrogen radii maximum (was: Hi! two completely unrelated questions)

1.If the Higgs boson is found (if it really is the Higgs boson, not a "Higggs-like particle" only) is there any experimental observation that can not be explained by the standard model? (and I'm not talking about the questions in scientific topics other than what physics is concerned about, like chemistry and biology, or even topics in physics like, I don't know, fluid dynamics, you know what I mean)

2.In an attempt to have fun with physics, I wanted to calculate that if we conducted a hypothetical experiment for checking where an electron is around a proton every nano second for 10^100 years (the biggest estimate I found for the lifetime of the universe) what is the farthest it will be found from the nucleus, given the probability distribution given by the 1s orbital's wave function. Now here's what I did, I calculated $\int _{r}^{\infty }\psi ^{2}\,dv={1 \over 10^{100}\times 31,557,600\times 10^{9}}$ where $\psi$ is the 1s orbital wave function in Hydrogen. well, wolphram alpha gives complex valued answers... what am I doing wrong?

thanks, the poster known as irrational number--2.177.20.5 (talk) 20:45, 4 July 2012 (UTC)

Your first question is answered in the second paragraph of the Standard Model article: "it does not incorporate the physics of dark energy nor of the full theory of gravitation as described by general relativity. The theory does not contain any viable dark matter particle that possesses all of the required properties deduced from observational cosmology." - emphasis added. --Tagishsimon (talk) 23:31, 4 July 2012 (UTC)

A Higgs at 125 GeV should be able to achieve dark energy with a simple scalar field parameter, but the Standard Model did not include such a particle until today. The light element big bang nucleosynthesis ratios will have to be recomputed. I expect them to be compatible with 100,000 solar mass black holes as dark matter,[6][7] primordial,[8][9] non-primordial,[10][11] or both.[12] 75.166.192.187 (talk) 00:59, 5 July 2012 (UTC)

In answer to number 2, I get 140 Bohr radii (about 7.4 nanometers) by doing the calculation you suggest. Perhaps you forgot to use a volume integral or something like that? Of course you can't really do that experiment, since any process for measuring the atom that extensively would change its behavior. Dragons flight (talk) 01:12, 5 July 2012 (UTC)

Regarding (2), please see Timeline of the far future. 75.166.192.187 (talk) 01:29, 5 July 2012 (UTC)

You probably need the integral of abs(psi)^2 157.193.175.207 (talk) 07:50, 5 July 2012 (UTC)

Mosquitoes

This may be a stupid question, but do mosquitoes only bite and take the blood from humans? I tried looking up the answer but it didn't show up. Plus, it seems a little odd that on a planet with millions of species, mosquitoes would only seek the blood of a singular species. Thanks, 64.229.5.242 (talk) 23:04, 4 July 2012 (UTC)

Per various sections of Mosquito, some of the beasties feed on vertebrates, including humans. But including all sorts of other animals. I don't know if any of the many types of mosquitoes specialise in humans; our article isn't very clear on that point. --Tagishsimon (talk) 23:17, 4 July 2012 (UTC)

There was a piece on a TV news show recently, possibly CBS Sunday, that discussed mosquitoes. Certain types of skeeters have "developed a taste for human blood", and of course those are the ones carrying various really-bad microbes. ←Baseball Bugs ^{What's up, Doc?} carrots→ 01:14, 5 July 2012 (UTC)

Mosquitoes are the most common big-bodied warm-blooded animals in many areas. Before that was Jurassic Park. μηδείς (talk) 01:29, 5 July 2012 (UTC)

By mosquitoes, I take it you mean humans ? StuRat (talk) 03:19, 5 July 2012 (UTC)

D'oh! μηδείς (talk) 03:39, 5 July 2012 (UTC)

I often confuse blood-sucking parasites, too. StuRat (talk) 01:00, 6 July 2012 (UTC)

Incidentally, there were also some 64-65 million years between dinosaurs and humans, and skeeters had plenty of food then too, I'm sure. StuRat (talk) 07:15, 6 July 2012 (UTC)

I have worked in remote areas, camping out, where I was the only human for 30km or more, and been bothered by mosquitoes. I've squashed them before they've had a chance to feast on me, and found them full of blood. I can only assume they had recently had a good feed on nearby wallabies (small kangaroos), rabbits, rats, etc, and think I might be a nice desert. Mosquitoes are quite an annoyance in many parts of Australia, but getting mosquito-borne disseases is very rare. This indicates that the same mosquitoes that feed on humans must be mostly feeding on wildlife whose significant viruses are not human-capable. (Ross River Virus, a nasty bug prevalent in the south-west, is one exception). Ratbone124.182.173.101 (talk) 01:37, 5 July 2012 (UTC)

Mosquitoes absolutely bite from a wide variety of animals, and each species has its own preferences. Most mosquitoes are willing to bend their preferences if their favorite food source is scarce, which is why we can raise many of them in the laboratory by feeding them mice. There are three reasons why a mosquito might prefer people: 1) It is an ecological niche filled with delicious protein. If an insect can efficiently fill that niche, it will, and it will be the best damn human-seeking blood sucker it can be; 2) Humans make it easy for species like Aedes egypti to breed in their own settlements by leaving water just sitting around for them to lay eggs in; 3) Some mosquitoes, to avoid their own predators, only hunt at night. Thanks to humanity's love of night-lighting, we tend to be the easiest prey at such times, especially on moonless, starless nights. In one study researchers captured nocturnal mosquitoes and analyzed the blood inside those who had recently fed. They found that, for these particular species, the suckers had a diverse palette on nights the moon was out. But on very dark nights, be it when the moon is unlit in the sky, or when it is concealed by clouds, the mosquitoes mostly fed on humans. And a secret fourth reason might be that we have no fur. If you ever watch a mosquito swarm feast on an unconscious mouse, they strongly prefer to bite bare skin, such as on the tail. Someguy1221 (talk) 01:47, 5 July 2012 (UTC)

Which are the best abatement products? There are some really good ones these days. 75.166.192.187 (talk) 02:48, 5 July 2012 (UTC)

As everyone has already said, yes mosquitoes most certainly do feed on other animals. Another example is Myxomatosis which is a disease that was introduced in Australia to try to control the introduced rabbit population. It spreads between rabbits by fleas and mosquitoes. Vespine (talk) 03:34, 5 July 2012 (UTC)

Note that the hybridization of mosquitoes can lead to new patterns of disease transmission, such as West Nile virus (see [13]). Many species are hybridizing presently as there are constant introductions, changes in range due to human modification of the land or global warming, and new environmental challenges for which hybrids have more genetic diversity to work with. As the old species gradually abandon their staid reserve and take on the greater adaptability of mixed genomes, we will discover that Nature has the power to get a whole lot meaner when provoked. Wnt (talk) 15:48, 5 July 2012 (UTC)

Glue and Plant Tissue

For an experimental project, I need an adhesive that can be in close proximity to growing plant roots without affecting the tissue. In other words, the glue should be biochemically "neutral" as far as the plant is concerned. The plant should grow the same way whether or not the glue is present.

The plant would not be placed in contact with the glue before the glue had set.

As far as the strength of glue needed, probably any of these would work. Silicone, epoxy, "crazy" glue, construction adhesive, or hot glue.

Can anyone tell me which if any of these will not affect the plant? Or suggest an alternative? Thanks, Wanderer57 (talk) 23:18, 4 July 2012 (UTC)

Silicone or, better, various types of wax will be non-irritating, but lack of air might be a problem. Can you not make the binding mechanically? I would look into grafting methods to find various binders that don't harm the plant.

Agreed. Toothpick splints and wire twist-ties? 75.166.192.187 (talk) 01:01, 5 July 2012 (UTC)

If you choose silicone, choose nuetral cure silicone sealant (used as fish-tank glue, roof-sealant, and other applications requiring compatibility with metal). Non nuetral-cure silicone slowly emits acetic acid for months after it has set, and the acetic acid might affect the plant. If the silicone is not specifically labelled as "nuetral-cure" and not specifically labelled for use in contact with metal, it is almost certainly the acetic acid kind. Ratbone124.182.173.101 (talk) 01:44, 5 July 2012 (UTC)

Funny, I had fishtank glue in mind. Didn't realize there was an acidic kind. μηδείς (talk) 03:37, 5 July 2012 (UTC)

Thank you all. Three very good answers in a few hours. Once again, the Wikipedia Reference Desk proves to be a brilliant resource. Wanderer57 (talk) 02:58, 5 July 2012 (UTC)

If you're still interested, the field ecologists I know use regular elmer's glue. One common use is to glue seeds to toothpicks for planting. The glue doesn't even interfere with germination. SemanticMantis (talk) 14:11, 5 July 2012 (UTC)

Thanks. I'm very much still interested. Wanderer57 (talk) 18:47, 5 July 2012 (UTC)

Elmer's glue is water-soluble. Won't the roots get wet, then dissolve the glue ? StuRat (talk) 00:58, 6 July 2012 (UTC)

I probably should have mentioned this. The experiments require a humid environment. The purpose of the glue is to attach components together in a particular configuration. This will create a space in which roots can grow. The plant roots and stems will not themselves be glued to anything.

Based on the above inputs, I'll begin experimenting using neutral cure silicone and grafting wax. Wanderer57 (talk) 22:20, 6 July 2012 (UTC)