Wikipedia:Reference desk/Archives/Science/2009 December 21

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December 21

Y-DNA different from groupings of associated mt-DNA in the Near East?

Hello eveyone,

Some months ago I found an article in Wikipedia which referenced males in a population of traditional people in the Near East that had Y-DNA groups that were unassociated with the mt-DNA of the women of the tribes people. This article seemed to suggest that the males may have migrated to the region in question from the north and supplanted the earlier males, perhaps violently. The article was associated with the Y-DNA tabs.

Many, many thanks!

Can anyone help? 72.153.250.16 (talk) 03:22, 21 December 2009 (UTC)

Did you forget to ask a question? Dauto (talk) 04:27, 21 December 2009 (UTC)

Sounds like OP is looking for the article. Vespine (talk) 05:06, 21 December 2009 (UTC)

I couldn't find any articles that fit your description. You might try starting at Archaeogenetics of the Near East. Also, near the bottom of Haplogroup_Q1a3a_(Y-DNA) there is an explanation on how Y-DNA and mt-DNA groups overlap. Jkasd 09:49, 21 December 2009 (UTC)

If all you're looking for is an example of that type of situation, the demographics of the Faroe Islands might help. (If you're particularly interested in the Near East, then sorry for the irrelevancy.) Felis cheshiri (talk) 18:01, 21 December 2009 (UTC)

A couple of articles like this are mentioned in New Scientist, newscientist.com and search archives with "mtDNA". Polypipe Wrangler (talk) 11:55, 26 December 2009 (UTC)

human sex determination

I have a question about sex determination, so I did a search here and found a similar question but no one seems to have really answered it. I have read that a recent study has found that the rate of male birth is actually falling to below 50% in places where it was typically over 50%. The historical number being over 50% was attributed to males typically partaking in more dangerous activities and therefore having a slightly lesser chance of reaching maturity. I was discussing the 1st point with my fiance and she picked me up on the 2nd, she refused to believe this was possible for "evolution" to know how many men were dying and besides, didn't a lot of women historically die during child birth anyway, while men could go have more kids, so wouldn't that make up the numbers? and I couldn't really come up with a good argument to support it. I can believe that even though it depends on 2 chromosomes it's not purely a 50/50 thing, that there can be a very slight evolved tendency to produce more of one sex then the other.. The XY sex-determination system doesn't even mention a ratio or if there are any factors that effect it. So I'm not sure what my question is, I suppose just does anyone know of any sources that address these topics? Vespine (talk) 05:34, 21 December 2009 (UTC)

According to human sex ratio, the ratio is 105 boys for every 100 girls. Jkasd 09:26, 21 December 2009 (UTC)

There was an editorial in Human Reproduction [1] about the genetic and non-genetic determinants of the human sex ratio at birth. Among the possibilites: High parental testosterone levels at the time of conceptions are associated with the subsequent birth of males. Low parental testosterone levels at the time of conceptions are associated with the subsequent birth of females. Some of the HLA genes, by controlling concentrations, partially (and weakly) control the probability of producing a boy. Your fiancée has committed the scientific sin of personifying evolution; evolution knows nothing, yet the environment (such as a shortage of males and an excess of females in the population) has clearly been demonstrated to effect sex distribution in other species (such as fish that undergo protogyny). -- Nunh-huh 10:05, 21 December 2009 (UTC)

That may be true, but for the record you are misunderstanding what the fiancée believed. - Jarry1250 ^{[Humorous? Discuss.]} 15:48, 21 December 2009 (UTC)

If "a certain ratio of males of a certain age-group" is an advantage, Nature doesn't need to "know" that or decide before-hand how to get that ratio--whatever genetic accident or coincidental set of traits leads to that situation gets there is what becomes passed on to the next generation. If males tend to die earlier because of certain behaviors and other circumstances, that trait will be selected against if those additional males were "needed" for genetic survival. If males tend to die earlier but also are more likely to be born, that sounds like a recipe for improved likelihood of passing on those genes. Nature just chooses what works best, there doesn't have to be a cause-and-effect feedback among specific traits. DMacks (talk) 16:20, 21 December 2009 (UTC)

Sure, sorry I should have qualified I understand evolution does not "know" anything. I suppose the hurdle is that sex determination is much more complicated then a "genetic trait" so the mechanism of sex selection is difficult to comprehend. For example, if sex was like "eye colour", nothing you do will change the ratio of eye colour, if there are 2 different genes and the dominant / recessive relationship is understood, the ratios are rigid and not affected by evolution / selection pressure. One blue eyed person and one brown eyed person can't increase or decrease the ratio of blue:brown eyed offspring they will have, short of evolving a new genetic mechanism for the process, (like could the blue eye gene evolve to be dominant if that trait was selected for long enough? in either case I digress). So I suppose the main thing here is that it is a mistake to apply the genetic analogy to sex chromosomes, which seems at least a bit counter intuitive. Vespine (talk) 23:26, 21 December 2009 (UTC)

You may be interested in Fisher's principle. Roughly speaking (and ignoring plenty of caveats), species with two sexes ought to evolve so that the ratio of the sexes is 1:1 among individuals of reproductive age. You might be able to imagine many ways this could be achieved, even if males die more; for example, y-bearing sperm might have some kind of advantage in fertilizing ova. Adrian J. Hunter^{(talk•contribs)} 07:05, 23 December 2009 (UTC)

Wireless video transmission solutions for HD video

What are current Wireless video transmission solutions for HD video ? I need something which can works at a maximum range of 2-3 Km.--yousaf465' 06:30, 21 December 2009 (UTC)

If there is line of sight, then a microwave transmitter and receiver (miniature dish) should suffice. This is the same technology as home WiFi, but at higher power (my internet connection is delivered this way). Regulations vary depending on where you live. No doubt an expert here or on the computing desk will be able to provide technical details. Meanwhile, our article Microwave#Communication provides some information. Dbfirs 10:35, 21 December 2009 (UTC)

The issue is really one of bandwidth versus quality. Because you can use a range of lossy compression levels and frame rates, there is not one solid "bandwidth" number to demand. 1080p video really needs around 6Mbits/sec for good quality - but can run anywhere down to 2Mbits/sec for poor quality. There are also a range of WiFi bandwidths...802.11g (which is pretty common in short-range applications) can manage 54Mbits/sec - which is just fine. Older 802.11b links are 11Mbits/sec - which is becoming marginal - or straight 802.11 at 2Mbits/sec which is flat out unusable. But all of the 802.11 standards are designed for much less than a 1km range. Cellular wireless only has to get as far as the nearest cell tower - and then the range is unlimited but bandwidth isn't good enough unless you can get onto the very latest 4G networks. From a fixed location - with line-of-sight access, then a microwave link is the best option. SteveBaker (talk) 20:02, 21 December 2009 (UTC)

For completeness, I should mention Wireless HD and Wireless Home Digital Interface standards, which are designed precisely for wireless transmission of (uncompressed) HD video, but only within a house (few 10s of meters). For the ranges the OP is asking about, WiMAX and competing WWAN technologies would be the closest fit; they have the bandwidth to support HD video, although in practice they are used for mobile internet access. Abecedare (talk) 22:06, 21 December 2009 (UTC)

Actually what I want is to transmit HD for FPV, so line of sight is a big no there. Will WiMax will work on such a platform ?--yousaf465' 03:34, 22 December 2009 (UTC)

Branes and Strings

What is the difference between a brane and a string? I know that there can be branes with different numbers of dimensions, but is that it, is the only difference the number of dimensions, or are they supposed to be something completely different. Would a one dimensional brane be like a string? If so then what role do other diomensional branes play? I know in versions of string theory that branes are the barriers between seperated dimensions, but do they do anything else, are there new types of particles we haven't discovered yet that are 0-branes or anyother p-branes? I know these are stupid questions but i have seen different sources saying strings are 1 dimensional branes but also some sources that seem to imply that they aren't the same thing, i just wanted to get a clear answer. —Preceding unsigned comment added by 74.67.89.61 (talk) 11:01, 21 December 2009 (UTC)

Avatar (2009 film)

When James Cameron said that he waited years to make this movie because he was waiting for technology to catch up, what technology is he referring to? --Reticuli88 (talk) 14:20, 21 December 2009 (UTC)

Our article mentions several technologies, including computer-generated character design, improvements in motion capture, real-time integration into a digital environment, facial expression capture and 3D cinematography. Gandalf61 (talk) 14:33, 21 December 2009 (UTC)

...at a price that the movie company could afford. All of those things have been possible for quite a while now - but only recently are they becoming cheap enough to allow this kind of adventurous stuff. SteveBaker (talk) 19:40, 21 December 2009 (UTC)

Superstring Theory and the Large Hadron Collider

In layman's terms, how could the Large Hadron Collider results prove the Superstring Theory? --Reticuli88 (talk) 14:25, 21 December 2009 (UTC)

There are versions of string theory that say, basically, "something interesting will happen when particles of high energy are hit together." The problem is, those "high energies" are very high—they might be high enough for the LHC to reach, but its just as possible that they are much higher than the LHC can reach.

So if the LHC makes those interesting things happen (which are fairly hard to explain in layman's terms that make sense—without writing a treatise on string theory), then we can say, "well, that prediction of that version of string theory seems to have something going for it." But if that doesn't happen, that doesn't actually tell us much. It doesn't tell us whether string theory is wrong or whether the amount of energy necessary for these experiments is more than the LHC can provide.

This inability to be strictly tested/falsified is one of the main criticisms of string theory. There's no real way to tell if it is wrong or not. --Mr.98 (talk) 15:06, 21 December 2009 (UTC)

That's what the critics say. But that's really not a valid complaint. There is a very important difference between 'hard to test' and 'non-testable'. Dauto (talk) 16:01, 21 December 2009 (UTC)

Well, it's a fine line, I think. If the answer by the theorists (of whatever theory) is, "well, you didn't disprove this, because it's just higher than you could see," at basically every stage, that's when we get into "non-testable" territory in the sense that falsifiability is really important (you can't distinguish between the theory being true and being false). That doesn't necessarily make it false, of course, but if the theory cannot provide any results that would distinguish it as actually existing in the world, it does make one wonder what the point is, and whether it is worth spending money on. I'm not a physicist at all, but I do find the fact that proponents of string theory have basically had to throw out falsifiability, and instead take up new criteria (e.g. "elegance") somewhat problematic. I think there is a lot to be said for falsifiability—and a lot to be worried about in more abstract and more subjective criteria. --Mr.98 (talk) 17:53, 21 December 2009 (UTC)

A lack of falsifiability certainly doesn't make a hypothesis false. But if you have to compare two hypotheses that cover the same terratory - neither of which has been proven - then the smart money goes with Occam's razor and picks the simplest ("the most elegant"). So if (for example) we have on the one hand that this simple equation explains something - and on the other hand that mutant ninja space-zombies did it using magic - then you go with the equation, even though neither hypothesis is known to be either true or false. If I modify my mutant ninja space aliens hypothesis by saying that they live on the planet Gaark in the Andromeda galaxy and give you precise coordinates for that planet - then technically my hypothesis is now falsifiable because you could go there and look for them...but you're still going to go with the unfalsifiable one-line equation because the mutant ninja theory isn't practically testable without significant advances in space travel.

That's roughly where we're at with string theory - we can neither prove nor disprove it (yet) - and whilst it may theoretically be falsifiable, it may be impossible to disprove without a lot of equipment that humans may never be able to build. But if it can be shown to be more elegant than the alternatives, then we should probably assume that it's likely to be true until/unless we either prove or disprove it with an experiment - or until we find an explanation that's yet more elegant.

SteveBaker (talk) 19:36, 21 December 2009 (UTC)

The problem with Occam's Razor and "elegance" in general is that when we are talking about physics at this level, it's not clear at all what the most "elegant" or "simple" solution is. If you play with the parameters and definitions enough, you can come up with all sorts of "elegant" but meaningless things, and one person's "elegance" is another's unphysical idea. (In the history of physics, this is extremely pronounced. What Einstein found elegant was detestable to the aether physics; what Bohr and Heisenberg found elegant was incomplete to Einstein, "disgusting" to Schroedinger, etc.) It is not philosophically satisfying, IMO. And given how many sub-flavors string theory has... it's hard for me to see how "elegance" is really going to get anyone out of the "which is the right one" conundrum. (As a historian, it reminds me quite a lot of the "elegant" and intricate work that was being developed on the aether in the late 19th century. Today we only really learn about how wrong the aether was, and not how it revolutionized physics at the time, provided new tools for theoretical investigations, and sustained a whole generation of brilliant theorists.)

Personally, I am much more satisfied by an explanation that says, "Well, yes, it is problematic that we have no way to determine which one of these is correct, if any. However, a lot of people seem to think this makes more sense than any alternatives we have at the moment, so it's probably worth pursuing further." That has a bit more humility than most string theorists seem capable of, though. ;-) --Mr.98 (talk) 20:20, 21 December 2009 (UTC)

Battery voltage

Inside a battery, there are two reservoirs of chemicals, one with too many electrons and another with not enough electrons.
1) Is voltage the difference in charge between the two resevoirs of the battery?
2) If yes, how come the voltage of a battery doesn't gradually decrease?
P.S. I tried reading the section Battery (electricity)#How batteries work but it is too difficult for me to understand. Lova Falk (talk) 14:59, 21 December 2009 (UTC)

1) No, the voltage difference is not the difference between charge. Both half cells are neutrally charged. What is different is the reduction potential of the half cells. This is not how many electrons each half cell has; its more related to how much each electrode in that half cell "wants" electrons.

2) Actually, in a "wet cell" battery, voltage does gradually decrease. Per the Nernst equation, voltage is related to the relative concentration of the electrolyte component of each half cell. However, in a "dry cell" battery (i.e. just about any battery you ever encounter except the one in your car), the "electrolyte" is in the solid state. Since the concentration of solids does not effect chemical equilibrium much, the voltage will not drop appreciably until right before it "runs out". --Jayron32 15:32, 21 December 2009 (UTC)

Going back to the water and pipes analogy. Imagine a lake up on a mountain connected to pipes that let the water come down the mountain to a second lake. The total charge of the battery is analog to the total amount of water in the lake on the mountain while the voltage of the battery is analog to the height of the mountain. Dauto (talk) 15:44, 21 December 2009 (UTC)

Except in this case it falls apart. The water in the lake continues to flow at the same pressure until the lake runs out. In a normal "wet" half-cell, it doesn't work that way. Voltage drops off directly as the battery "runs down". See Nernst equation In dry cells, the lake analogy works a bit better, but only because of the way solid state chemistry works. --Jayron32 16:17, 21 December 2009 (UTC)

Are you sure? Less water above the outlet pipe = lower pressure. Felis cheshiri (talk) 18:27, 21 December 2009 (UTC)

I get the image of the amount of water and its height, but in the battery I can't understand why voltage is needed. If there are too many electrons in one resevoir, why do they need to be pushed by the voltage to move to the other resevoir? Isn't the difference in charge enough to create an attraction and to get them going? Lova Falk (talk) 18:34, 21 December 2009 (UTC)

The electrons do not need to be pushed by an externally imposed voltage. They create the voltage themselves. The voltage is just an expression for the electric fields created by the electron imbalance.

The chemical potential enters the picture when we draw current from the battery. When we let current flow between the terminals, the voltage will drop below the level where the chemical reaction can take place, and the reaction will then replenish the electron excess to that level -- until we run out of chemicals to react. –Henning Makholm (talk) 05:00, 22 December 2009 (UTC)

I would say that there are two reservoirs of chemicals which, if they were combined into one or more new compounds, would have less chemical energy than before combination. A simple example is the fuel cell; everyone knows that hydrogen and oxygen have more chemical energy when they are separate gases (inside and outside of the Hindenburg, for example) than after they are combined into water. In a cell, some of the sub-atomic particles of the atoms involved in the recombination travel through different paths to get to the other side of the battery; positive ions travel within the cell while electrons travel through a circuit. Some of the energy that is always released when chemicals recombine into a lower-energy form is expended in the circuit. --Jc3s5h (talk) 15:57, 21 December 2009 (UTC)

It's not really that there are "too many electrons" Look at it this way. For a given element, there are multiple states it can exist in: Lets simplify it and take it as two states: An "oxidized form", which has less electrons, and a "reduced form" which has more electrons. For metals, the "oxidized form" is called an ion, while the "reduced form" is basically just the pure metal. Every substance can, under certain conditions, interchange between the "oxidized" and "reduced" states. Every metal has a property called its reduction potential, which is basically a measure of how tightly it holds on to electrons (i.e. how much it "prefers" to stay in the "reduced" form).

A half-cell is basically a metal and its ionic form brought into contact. Picture a beaker of water with iron ions floating in it, and a solid chunk of iron stuck in the water. So what you have is a system which, depending on the conditions you put it under, can either oxidize (metal --> ion; losing electrons) or reduce (ion --> metal; gaining electrons). If you bring two different half cells into contact, they each have a different reduction potential. These two half cells will exchange electrons such that the one with the higher reduction potential will take electrons from the half-cell with the lower reduction potential. What you have just created is a battery. Now, here's the deal, you can't build up electrons in any one half-cell, so another important thing is you need a way for ions to exhange between the two half cells so that the charge balances out. What you end up with is electrons flowing in one direction and ions flowing in the opposite direction to keep everything balanced out. There is no net change in electric charge.

Its also important to remember that electrons aren't "Stolen" or "taken". What happens is that the electrons have a lower amount of energy in the "dead" battery than in the "charged" battery. Being at a lower energy means that its a more stable state, and all chemistry will proceed spontaneously down an energy gradient. Its like placing a ball on a slope. It rolls down the hill because it has less energy at the bottom of the hill than at the top. The electrons are exchanged in a battery spontaneously. --Jayron32 21:28, 21 December 2009 (UTC)

I would say that there is an electron excess on the negative electrode; that's what creates the potential difference we can measure between the terminals. Ultimately, the electric fields reacts only to where the charges are located; if there is a field, there must be a charge imbalance that causes it. The pure geometric capacitance of the battery is usually low, so the electron excess is appropriately tiny, but it is there.

Then, of course, the electron excess itself is caused by chemical reaction. One of the effects of the reaction is to move charge from one electrode to another. If there's already an excess of electrons on the negative electrode, the reaction must do work against the field, which shifts the equilibrium enough that the reaction stops once a certain voltage is reached. Once we start drawing current from the battery, the charge imbalance (and therefore the voltage) lessens a small bit, which causes the reaction to start up again and replenish the imbalance to the equilibrium level. By this mechanism the charge excess, and therefore the voltage, stays approximately constant until we run out of reactants (at which time the battery is dead).

If the reaction rate cannot keep up with the rate at which we draw current, the charge excess will be getting smaller, which makes the voltage smaller, which again makes the reaction quicker until a new dynamic equilibrium is reached. This accounts for the "internal resistance" of the battery. –Henning Makholm (talk) 04:52, 22 December 2009 (UTC)

Chinese / Mongolian plant?

Wondering if anyone can identify this. I saw a program on food sold in China that included a plant called (roughly) "Far-zay" (ay like eye). The plant was black, looked kind of like a black moss with longish runners; when prepared for sale on the streets of China, it looked like black hair bundled together. Reportedly, it sells for 800 Euro a Kilogram and its sale is forbidden by the government because collecting it damages the grasslands where it is found in Inner Mongolia. Thanks for any information. Someone looking at it on the program identified it as a kind of blue-green algae. Cheers, W. B. Wilson (talk) 17:45, 21 December 2009 (UTC)

Made me think of Cordyceps sinensis; but it's most likely something else. --Dr Dima (talk) 17:57, 21 December 2009 (UTC)

Fat choy? Felis cheshiri (talk) 18:15, 21 December 2009 (UTC)

That's it -- thanks! Cheers, W. B. Wilson (talk) 18:19, 21 December 2009 (UTC)

More on it here

Cholecalciferol

I've read the article and have a question you might answer or point to an answer. An opthalmologist who does hot respond to inquiries has prescribed a multi-vitamin with 2,000 BTU of Vitamin D3 or cholecalciferol. Nothing in the article referred to how use of this multi-vitamin contributes to eye-health, other than perhaps indirectly by strenthening the immune system. Any advice or suggestions? —Preceding unsigned comment added by Lschaffel (talk • contribs) 18:27, 21 December 2009 (UTC)

My advice is that articles are only as good as those who write them, and probably not even that good, because articles are rarely kept completely up to date with all facts and figures covered. For example, periodontitis has many systemic tie-ins, but you'd never know it from the article. I'm certain that all if not most of the drug articles in Wikipedia, while being excellent sources of both primary and secondary information, are incomplete in the sense that multiple facets of their prescription (both label and off-label) information, pharmacodynamics, pharmacokinetics, contraindications, history, r&d, etc. are not in the article (yet). Be bold, or just understand that while Wikipedia attempts to contain all information about all things, it doesn't actually do so at the present time. DRosenbach ^{(Talk | Contribs)} 04:03, 22 December 2009 (UTC)

Is L-alanine l or d?

Would compounds with L-alanine as a substituent also retain the light behaviour of L-alanine (assuming no other chiral centers) or are such properties not conserved? John Riemann Soong (talk) 20:03, 21 December 2009 (UTC)

In general you cannot predict the levorotatory or dextrorotatory behavior of compounds from their structures. However, the "L" and "D" in L- and D- sugars and amino acids refers not to the optical rotation given by the compound, but is based on the similarity of structure to parent compounds. So any L-alanine derivative will be an "L" amino acid, even if it was dextrorotatory. -- 128.104.112.94 (talk) 22:01, 21 December 2009 (UTC)

In fact, the specific answer to your question is found in those articles: "nine of the nineteen L-amino acids commonly found in proteins are dextrorotatory" Even though all 19 chiral amino acids can be thought of as alanine derivatives, you can see that about half have the opposite optical rotation of alanine. -- 128.104.112.94 (talk) 22:06, 21 December 2009 (UTC)

Even worse, changing a structure without altering its stereochemistry do not necessarily retain the same sign of optical rotation. R-alanine is –14.5° but its methyl-ester hydrochloride-salt is around +9°. DMacks (talk) 06:44, 22 December 2009 (UTC)

Genetics

A given person has a given genetic property (say: green eyes, or dark skin, and the like). That person has a child, and a sibling.

1. Who of them (the child and the sibling) is more likely to have that genetic property?
2. Does the answer depend on whether both siblings have one common parrent only?

HOOTmag (talk) 20:49, 21 December 2009 (UTC)

The Coefficient of relationship for parent/child and siblings are both 0.5, so if the genetic characteristic is determined by a single dominant gene the probability of it being shared between a parent and child or two siblings is 50%. For half-siblings it is only 25%. If the other parent also has this gene then obviously the probability is higher. If the characteristic is determined by multiple genes it is very complicated. If the characteristic is determined by a single recessive gene then the probability will be determined by the what genes the other parent has. --Tango (talk) 21:26, 21 December 2009 (UTC)

Thankxs a lot, for your detailed answer. HOOTmag (talk) 21:33, 21 December 2009 (UTC)

Tango pretty much got the whole answer except perhaps if this is a homework question it would really help if you actually understood why that is. So I might just add, your child has a relationship of 0.5 because they inherit 50% of your genes direclty, however your sibling actually has a chance to inherit more then 50% or less then 50% of the same genes from your parents, but that ratio is equal too so the average still works out to 0.5. Not counting identical twins. Vespine (talk) 21:39, 21 December 2009 (UTC)

And the phenotype (green eyes, etc.) may not be expressed. Which I think should be obvious but if this is homework, maybe it is not. Get 50% of the genes does not mean you have a 50% chance of having the same expressed eye color—it is more complicated than that. --Mr.98 (talk) 22:45, 21 December 2009 (UTC)

I did consider the above but exactly the same rule will apply whether you are talking about a sibling or an offspring so that particular factor will cancel it self out and not affect the result. Vespine (talk) 23:34, 21 December 2009 (UTC)

To be pedantic, I wouldn't classify phenotypes as "genetic properties" -- phenotype would be more like "physical properties" that are (at least predominantly) genetically determined, while genotypes would be genetic properties. DRosenbach ^{(Talk | Contribs)} 02:19, 22 December 2009 (UTC)

OP's comment: Tango's answer is sufficient for my needs. My original aim has been: to inquire whether the Inheritance Law (in some ancient cultures) can be reasoned by a genetic explanation. HOOTmag (talk) 15:49, 22 December 2009 (UTC)

How does inheritance law have anything to do with genetics? DRosenbach ^{(Talk | Contribs)} 18:34, 22 December 2009 (UTC)

For example, one could investigate the following rule:

• The higher the coefficient of relationship is, the higher the priority of inheritance is.

HOOTmag (talk) 19:02, 22 December 2009 (UTC)

Except that in many/most inheritance schemes, males are disproportionately favored, and it is usually the eldest male who gets favored most of all. This is not related to genetics between siblings (which are the same), but the economics of these particular cultures. I am not sure the genetic analysis really tells you too much, other than the "we are trying to benefit the future of the line" point which is rather obvious and fairly vague. --Mr.98 (talk) 21:56, 22 December 2009 (UTC)

Recycleability of yellowed paper?

I recently discovered a yellowed newspaper (date of October 2007) in my house and placed it in a bag where I put a new newspaper that I've finished reading. Realistically speaking, is the old newspaper recycleable, or has the acid damaged it too much? The paper wasn't brittle or falling apart, but it felt distinctly "soft" in a way that nothing but yellowed newspaper does. Nyttend (talk) 21:24, 21 December 2009 (UTC)

Yellowing newsprint is typically not accepted as being recyclable according to many organizations' guidelines. Tyrol5 [Talk] 00:21, 22 December 2009 (UTC)

I've never come across such a restriction & would be surprised indeed if such existed. Citation required, as they say. It seems counter-intuitive to say that such paper is not welcome at the recyclers. It'll have a raised acid content, but pH can be altered easily enough. It still has fibres. The output of the processes is segmented into various grades of paper ... really, I can't see a problem, nor can I with ease find one through google. --Tagishsimon (talk) 00:33, 22 December 2009 (UTC)

The main reason I was curious was the state of the fibres — I thought that they might have broken down a bit in the 26 months since the newspaper was published. Do the fibres stay intact even while the overall page of paper deteriorates? Nyttend (talk) 01:07, 22 December 2009 (UTC)

I am not a paper scientist, &c., but opine that it is a matter of degree ... there will be some (probably minor) breakdown, but the paper is still substantially paper, holding together very well. Possibly it'll contribute more to the cardboard and toilet roll end of the recycled spectrum than the high laid paper end. In my brief google skim, yellowing is a result of molecular breakdown. Newsprint tells us that lignin is the cause. But remember also that the pulping process also breaks down fibres, which is why paper cannot be recycled indefinitely. --Tagishsimon (talk) 01:46, 22 December 2009 (UTC)

I thought at first Tyrol5 was confused with Yellow pages which are well known not to be acceptable for recycling in many areas. However, many local authorities are citing the difficulty of removing >year-old ink as the problem, rather than the colour [2][3] so presumably this also applies to year-old newspaper as well. SpinningSpark 02:16, 22 December 2009 (UTC)