Wikipedia:Reference desk/Archives/Science/2009 September 12

= September 12 =

dead cockroaches
I live in the cochella valley in California. We have many cockroaches (they are called palm beetles, but a cockroach by any name smells the same). I have noted what seems to me a very peculiar chracteristic: We find many dead ones in our garages and sidewalks and around the periphery of buildings. They are always on their back. I have not been able to see one in the throws od death so I'm not sure how or why they get on their backs. Does any one know or have a theory. Please, serious answers only. Thanks, wsc —Preceding unsigned comment added by 98.149.228.69 (talk) 00:09, 12 September 2009 (UTC)


 * It looks like no-one really knows... And, by the way, "palm beetle" is not the right name for a cockroach. Cockroaches are not beetles, they are more closely related to praying mantises and termites than to beetles. --Dr Dima (talk) 00:35, 12 September 2009 (UTC)


 * According to our article a palmetto bug is another name for an American cockroach -- that's probably the source of the confusion. Looie496 (talk) 01:19, 12 September 2009 (UTC)


 * Not being "right" does not mean it isn't in widespread usage. King Cnut had a better chance of turning back the tides than one has of changing an "incorrect usage" of a term like this.  Consider the confused state of a word like berry, for example.  Its so bad that MOST of the most commonly eaten fruits called "berries" are not really "berries" (botanically speaking) and yet no one is changing their name.  SO we are probably stuck with names like "palm beetle" and "palmetto bug" even though cockroaches are neither beetles or true bugs.   -- Jayron  32  04:10, 12 September 2009 (UTC)


 * Likewise with the woodlouse (a crustacean). Also, in England it seems quite common for people to refer to a single woodlouse as 'a woodlice'. --Kurt Shaped Box (talk) 07:19, 12 September 2009 (UTC)
 * ... surely not educated people in England?  D b f i r s   16:07, 12 September 2009 (UTC)
 * Yeah, srsly. It's very common, in my experience. It's a bit like the 'roll one dice' thing. --Kurt Shaped Box (talk) 21:00, 12 September 2009 (UTC)
 * From chance dialectal researches, I would have thought that everyone in England referred to them as cheeselips or cheeselouses or sow bugs or slaters or any of several other local names. Those curiously attractive little critters must have more common names than almost any other beastie. Deor (talk) 22:10, 12 September 2009 (UTC)
 * The only other name I've ever personally heard anyone say is 'pillbug'. Now, I'd only refer to the ones that roll up into a ball as 'pillbugs' - but if this one person is anything to go by, my way is not universal. The fact that we have so many different names for these little grey skittery things, to me suggests a close historical relationship between us and them... --Kurt Shaped Box (talk) 22:23, 12 September 2009 (UTC)
 * Two more local names: "piggies" (no idea why), and "thus lice" (th unvoiced - presumably originally Thor's lice because they look like giant lice). Even Maths text books have started using "one dice"!    D b f i r s   22:32, 12 September 2009 (UTC)
 * I call them waterbugs. Palmetto bug is understood. Sagittarian Milky Way (talk) 13:34, 14 September 2009 (UTC)
 * Perhaps being on their back (maybe after an encounter with another bug, or falling from a wall) is the cause of death, because they find they are too weak to right themselves.--Shantavira|feed me 07:54, 12 September 2009 (UTC)
 * They can right themselves, with difficulty. It might take 1-2 minutes. I've seen one die. It's so weak it couldn't possibly right itself. Maybe they all die that way, but that still wouldn't explain why it'd get upside down in the first place. Or maybe that one was sick, it defecated a black fluid (yuck!) They like basements. Sagittarian Milky Way (talk) 13:34, 14 September 2009 (UTC)

Respiration
I want to know the exact role of oxygen in respiration, otherthan oxidation of hydrogen? —Preceding unsigned comment added by Anurocks0605 (talk • contribs) 00:30, 12 September 2009 (UTC)
 * Cellular respiration is a very good article with ample information.  Intelligent  sium  00:54, 12 September 2009 (UTC)

Environmental impact assessment
My wife and I are thinking of having kids, but we think it would be prudent to have an environmental impact assessment done first. Whom should we consult? 99.225.250.31 (talk) 03:54, 12 September 2009 (UTC)


 * Environmental impact of what? Having a child?!?  -- Jayron  32  04:04, 12 September 2009 (UTC)


 * Not the process of having one, but the existence of one. 99.225.250.31 (talk) 04:12, 12 September 2009 (UTC)


 * I would imagine that would be extremely hard to do, bordering on nearly impossible. There are an absurd amount of factors, namely how you raise your child (to be the type of person who drives a Hummer or a bicycle, for example), how long they live, and what they do with their life.  You could look up average impacts for people living in your area, although I'd suggest trying to raise the child to simply be what you and your wife consider to be best.  You can also only have the one child, thereby reducing the population of the world (once you die); even better, you two can adopt! ~ Amory ( user  •  talk  •  contribs ) 04:21, 12 September 2009 (UTC)


 * Interesting point. Adoption would seem to be essentially impact-neutral, as the child already exists and adoption in general isn't driven by supply & demand theory. You may be increasing the average costs & impact of that child by bringing it into a wealthier situation, but compared to creating one from scratch you're orders of magnitude ahead!


 * Think globally. Adopt locally?213.146.164.142 (talk) 07:38, 12 September 2009 (UTC)


 * As all man made detrimental effects on the environment are made by humans it would be logical not only not to have children yourself but also to discourage everyone else of having children. I know this is highly cynical but that's not my fault. I think the sheer question as such is deeply flawed but in a way where the flaw can't be easily pointed out. And I think modern society needs to think about this type of questions. As of whom you should consult, this depends on what kind of answer you want. 95.112.165.86 (talk) 08:39, 12 September 2009 (UTC)
 * And following that concept to its logical extreme ... Mitch Ames (talk) 12:46, 12 September 2009 (UTC)

The problem with this is that your culture, which allows women freedom and reproductive choice, will be replaced by one that does not and turns women into breeding machines. If you take this "atruistic" approach, the problem will be even worse long term.80.0.102.60 (talk) 12:50, 12 September 2009 (UTC)
 * I have a hunch the OP's question vaguely ties to this one from the same IP some weeks ago: There's no question that there have been way too many unwanted children brought into the world. But that is presumably not the likelihood with the questioner. As noted by others above, humans in general have an impact on the environment - as does all life. It's a current human conceit that we somehow have a huge impact on the environment. I recall when Mt. St. Helens erupted, it was said that the amount of particle matter in that one relatively small eruption was more than all the fallout that all the bombs in the world could produce, or some such. Don't concern yourself with "environmental impact". Decide whether you want a child, and why; and determine whether you can afford it financially, i.e. to keep it from falling into the trap suggested by the question from some weeks ago. Those should be your main concerns. Don't worry about overpopulation. Mother Nature has a way of taking care of that over time. Baseball Bugs What's up, Doc? carrots 16:47, 12 September 2009 (UTC)
 * Well yes, there have been "natural" events that have caused more destruction than humans on the ecology of the planet. That doesn't mean that humans causing massive ecological destruction is inconsequential.  The environmental impact of humans does have a very real effect on the quality of life of humans.  For example over-population puts a strain on the resources available per person.
 * That's not to say that the OP shouldn't have a child. As other people have said, it's extremely hard to gauge the likely impact of an individual.  Some people have positive net effects on the environment, and it seems like someone raised by the OP is likely to be more environmentally conscious than average. Rckrone (talk) 17:18, 12 September 2009 (UTC)
 * That would be the best approach to take. Succumbing to fears about impacting the environment is self-defeating. Every living thing impacts the environment. Raising children to contribute positively would seem to be the optimal choice. Baseball Bugs What's up, Doc? carrots 17:28, 12 September 2009 (UTC)


 * A study has been done on this. One new person could result in "up to 10,000 tonnes of CO2." --S.dedalus (talk) 20:55, 12 September 2009 (UTC)


 * Every human being has a huge impact on the environment. So the logical outcome of an environmental assessment would be that we should all kill ourselves at once, leaving just enough people to shut down the nuclear plants. Unt of course, ve vould need schientists to schtudy zee impact! Rather than worry about the environmental impact of your child, why not worry first about minimizing your own environmental impact? Then participate in the efforts of human society to reduce our burden on the Earth as a whole? After that, you can reproduce to your approximate population replacement value (2.1 children or so, though I've never seen a .1 baby yet) and you can raise your children to the values of conservation and respect for the natural world that you've already incorporated into your own core value system. Franamax (talk) 03:44, 13 September 2009 (UTC)


 * Let me know if you decide not to have kids. That will live space in the world for me to have one more of my own... Dauto (talk) 07:09, 13 September 2009 (UTC)
 * You are currently limiting the number of kids you have to leave room for others? Thanks for that!  Please feel free to apply for your Darwin award! SteveBaker (talk) 18:01, 13 September 2009 (UTC)


 * One approach would be to take the List of countries by carbon dioxide emissions per capita and look up the country you live in (let's suppose that you live in the USA - so 20,000 kg per year) - and the life expectancy in List of countries by life expectancy - (for the USA, that's 76 years for a boy, 81 for a girl) and multiply the to together: 1500 tonnes for a boy, 1600 tonnes for a girl. Of course this assumes that the present rate of CO2 generation is constant for the life of the child (unlikely) and that all of the causes of CO2 emission is proportional to the size of the population (fairly likely on the scale of the US population).  But this is an easy calculation - and likely to be as accurate as it is possible to be without the use of a functioning (hopefully, wind-powered) time-machine.


 * However, that calculation also assumes that you raise your child in an "average" way. Alternatively, you could drum into your child the need to be super-careful about not producing unnecessary carbon dioxide - perhaps encourage him/her to become a vocal advocate to CO2 reductions - for bedtime reading, read the speeches of all of the great orators.  Later, support his/her candidacy for government - lead a political action committee to raise campaign funds - push his/her rise to power as the next leader of your country - resulting in a radical shift in public CO2 policies 30 years from now.  This could cause massive future decrease in emissions across the entire country as a direct result of your child being born.  Carried out successfully, even a 1% savings in CO2 emissions in the US would result in a massively negative carbon footprint direct resulting from your actions.


 * ...yeah...good luck with that!


 * But seen in that light - it's really impossible to predict the carbon footprint of your kid.


 * SteveBaker (talk) 18:01, 13 September 2009 (UTC)

the organic chemistry of carbon dioxide fixation (i.e. mechanism of RuBisCO)
Yet another carbonyl question. Does the RuBisCo enzyme use the idea of nucleophilic attack on the central carbon of carbon dioxide? I tried looking at some articles but they use really elaborate physical chemistry, wavefunctions and ... no electron arrow mechanisms. Yes, I realise electron arrow mechanisms are sort of simplified but can I please see one? (Mechanisms for simpler evolutionary predecessors to RuBisCO are also welcome). John Riemann Soong (talk) 07:04, 12 September 2009 (UTC)


 * It depends on which part of the mechanism you are looking for, the enzyme action or the overall reaction between the CO2 and the ribulose biphosphate. Probably the RuBisCO operates on the "Lock and Key" model; that is there are binding sites for both the CO2 and the ribulose biphosphate which are brought together to form the 3-carbon sugars which enter the Krebs cycle.  Our article on RuBisCO does not detail where on the molecule those binding cites are, but given that the molecular weight of RuBisCO is about 540,000, such detail is most likely out of the scope of a Wikipedia article.  The exact way the electrons are "pushed" to bring about the 3-carbon sugars is also not detailed in our article, but the six-carbon intermediate is apparently 3-keto-2-carboxyarabinitol 1,5-bisphosphate, which means that if you can work out the structre of THAT; you can work out the electron pushing diagram since you have two relatively simple reactants (the ribulose biphosphate and the CO2) and a relatively simple product.  -- Jayron  32  12:01, 12 September 2009 (UTC)


 * Is this it ? (full scheme)
 * Could someone from a free country please check the link? I could get in really big trouble if some jester set up a link to something that is illegal to view even by accident in our country. Tanks. 95.112.165.86 (talk) 14:00, 12 September 2009 (UTC)
 * That URL is safe. I's exactly what the URL describes: a faculty member at some school posting material for a lecture for his chemistry class. No Rick Roll or other nonsense:)DMacks (talk) 17:15, 12 September 2009 (UTC)
 * Thank you. Regretfully I and my countrymen will need such kind of support from free living people for unforeseeable times.95.112.165.86 (talk) 17:55, 12 September 2009 (UTC)
 * You need to be familiar with "electrophilic attack on enolates" eg http://www.google.co.uk/search?hl=en&q=enolates+reaction&btnG=Search&meta=
 * There's a useful acetone/'acetone enol form' electron density map here http://www.chem.ucalgary.ca/courses/350/Carey/Ch18/ch18-1.html which shows why enols can react with electrophiles at carbon
 * This  is a far better visualisation of the critical step, showing the role of Mg2+, and the mechanism too. (Don't even ask me how they worked that out - I haven't got a clue - probably isotope labling experiments or something).
 * (Note that the enol based attack isn't as simple as usual since there is a OH next to the keto - making the intermediate structure approximately a 1,2 dihydroxy alkene... see that technically the reaction forms a bond between two carbonyl carbon atoms!!)
 * 83.100.250.79 (talk) 12:15, 12 September 2009 (UTC)


 * Yeah I just started studying enol/enolate reacitons. And I am interested enzyme stuff besides the protein folding/induced fit stuff (which is fascinating but no too complex). I am interested in how the enzyme binds CO2, how the enzyme activates CO2 -- (why would CO2 make a ligand to Mg++? And is that a nucleophilic attack on the carbon dioxide carbon?) I find the sudden disappearance of two protons very interesting -- does the enzyme's basic amino acids somehow transport that away (without needing strong base in solution), because obviously that seems to stabilise the enolate intermediate long enough for CO2 to come in. What do the phosphates do in this step? John Riemann Soong (talk) 16:46, 12 September 2009 (UTC)

How did Eskimo or Inuit tribes defend themselves against polar bears before they had guns?
Since modern explorers use powerful guns for bear defence,what was their defence? 80.0.102.60 (talk) 12:43, 12 September 2009 (UTC)
 * No doubt the same as all peoples defended themselves against large predators before guns: with great difficulty. Plus fire, clubs, spears, organization, cunning, etc. -Sean 13:12, 12 September 2009 (UTC)
 * A google scholar search pointed me to Hunters of the Northern Ice, (unfortunately unavailable online) - an authoritative book on the cultural history of the Inuit hunters. More recently, discussions about conservation of bear and other wildlife seem to have a strong component of academic debate about just how embedded into Inuit culture these bear hunts really are/were.  Especially now that the hunts are done with firearms, there is academic debate about whether modern bear hunts really preserve a cultural legacy.  Polar Bear as a Resource cites the earlier book (and some other papers and books, but unfortunately these citations are hard to track down, and written in Quebecois ).  Nonetheless, the claim is that Inuit have been hunting nanuk for millenia.  Nimur (talk) 13:46, 12 September 2009 (UTC)
 * Warding off predators only requires being able to do enough damage to counteract your food value. A person carrying a harpoon can't "win" a fight with a polar bear, but can give the polar bear a very serious wound.  I believe the main threat from bears is in places where they rarely encounter humans -- when the two species mix, they learn to avoid each other. Looie496 (talk) 16:21, 12 September 2009 (UTC)
 * A vaguely similar idea occurs in signs in national parks advising what to do if encountering mountains lions, namely to fight back. Predators don't expect their prey to turn the tables on them, and unless they are really hungry, they will likely be warded off by a sufficiently painful defense put up by their potential prey. Baseball Bugs What's up, Doc? carrots 17:02, 12 September 2009 (UTC)


 * You can see this very clearly on a number of YouTube videos of bears vs. other animals. Grizzly bears, pound for pound, tooth for tooth, should be able to take just about anything in the forest, but there are lots of videos of them being basically run off by angry wildcats or wolves who are vastly smaller than they are and comparatively under-powered, but present enough of a trouble that the bear decides it would rather go elsewhere. There is one compelling one I saw awhile back of a very small wildcat that provided just enough threat that the bear decided to go eat some berries rather than potentially lose an eye. There's a lot to be said for not every fight having to be "to the death". --98.217.14.211 (talk) 18:03, 12 September 2009 (UTC)
 * Sounds similar to a video I once saw of a wolverine treeing a black bear. Not a grizzly, but still an impressive sight. Baseball Bugs What's up, Doc? carrots 20:12, 12 September 2009 (UTC)
 * Housecats have been known to do the same. Algebraist 20:17, 12 September 2009 (UTC)
 * And mice can scare the dickens out of people. Size is not everything. The peskiness factor figures into it. Baseball Bugs What's up, Doc? carrots 20:22, 12 September 2009 (UTC)


 * Compare the size of a human to that of a pitbull. Still, if a pitbull approached you snarling, with teeth bared, you'd likely instinctively run. --Kurt Shaped Box (talk) 22:56, 12 September 2009 (UTC)


 * Are you kidding? I would avoid a snarling chihuahua, never mind a pitbull. Basically, any critter armed with anything sharp (teeth, claws, stingers, etc.) is potentially dangerous. That brings up another point about the mountain lion. They say do not run. For one thing, the animal can probably outrun you easily. For another, it signals fear. If you stand your ground, you've got a better chance. No guarantee of success, but a better chance. Baseball Bugs What's up, Doc? carrots 23:02, 12 September 2009 (UTC)


 * It's a fair point - but it sounds like one of those things that's easier said than done. Standing your ground against a wild beast apparently intent on attacking you takes bollocks - and bollocks tend to shrink in the face of adversity, as the adrenaline and millions of years-worth of hard-wired instinct kick in and tell you to run for your life. Heck, some people run away when they see a spider on the wall. --Kurt Shaped Box (talk) 23:08, 12 September 2009 (UTC)
 * Awhile back, my wife moved to California from New England, and saw all of those "fight back against the wild cats! wave your hands in the air, and put your children on your head!" signs in the wilderness areas, and thought they must be a joke to fool people from out of the area into walking around waving their hands in the air, their children on their heads, for a good laugh from the locals. --98.217.14.211 (talk) 00:23, 13 September 2009 (UTC)


 * It's strangely a redlink, but the Life/Dinner Principle (originally discussed by Richard Dawkins, I think) notes that the prey has a much stronger incentive to go to the mat in a fight with the predator. --Sean 19:53, 12 September 2009 (UTC)


 * In many cases, a wounded predator is a predator that will starve to death. When you see (for example) lions hunting wildebeest on TV, there's a very good reason that they nearly always target the young, the old or the sick/injured. Whilst a lion probably could down take a healthy adult wildebeest, there's a very real chance that the wildebeest would inflict some nasty kicks on the way down. If one of those connected with a leg, then you've got one lion that won't be chasing after anything ever again... --Kurt Shaped Box (talk) 22:48, 12 September 2009 (UTC)
 * I watched a nature show once where a lioness took a kick to the jaw. She lived for weeks, but was doomed. :(  --Sean 13:22, 13 September 2009 (UTC)

As it says at Polar bear they used dogs to harry the bear while using spears or arrows. That of course is while hunting, but even when not hunting the dogs would give the alarm and then be let loose to go after the bear. There is the possibility that some Inuit might have used seal meat with sharpened bones inside to help kill bears. The idea being that the bear swallows the meat and the bones then puncture the stomach slowing it down so the hunters could catch up. Enter CambridgeBayWeather, waits for audience applause, not a sausage 18:59, 12 September 2009 (UTC)

They hunted them with dogs, knives, spears etc. Bear hunting gives lots of info on how to go about it. You can find more about the Inuit and their hunting at these pages: Inuit diet, Reindeer hunting in Greenland, Greenland Dog. Fences &amp;  Windows  23:18, 12 September 2009 (UTC)

SteveBaker (talk) 17:37, 13 September 2009 (UTC)
 * 1) They would know how to avoid attracting bear in the first place.  Bears do not naturally want to interact with humans - so if there is no open trash pile full of goodies - they are much less likely to bother us.
 * 2) These people live out in that environment their entire lives - they'd know where not to go and what not to do - they might simply never need to get involved with polar bears.
 * 3) In some cases, I'm sure they didn't succeed - and occasionally, they'd suffer an attack.  But so long as the number of incidents doesn't get too high, the consequences on the human population might not be so severe.


 * I disagree with part of Steve's first point. Polar bears are very unlike your aaaaverage bear; my understanding is that they consider people perfectly reasonable prey. Part of it, I'm sure, is lack of options; the high arctic is not a place where you turn up your nose at a meal even at the best of times. There is little or no plant life there - virtually anything a polar bear wants to consume is going to kick up some kind of fuss. I don't know where I picked this factoid up, but I've heard that polar bears and cougars are the only animals native to North America that consider humans fair game, though cougars would rarely be bold enough to attack full-grown humans or people in groups. Other animals may be dangerous, may even be more  dangerous in terms of possibility of being attacked/killed, but these are the two that will attack humans as a prey animal. Matt Deres (talk) 04:17, 14 September 2009 (UTC)
 * Not counting the mosquito, that is. Looie496 (talk) 05:39, 14 September 2009 (UTC)
 * Or Hannibal Lecter. Googlemeister (talk) 14:11, 14 September 2009 (UTC)

biosynthesis of phosphoric acid (charge balance on DNA part deux, OMG)
One thing that has come to amaze me is the sheer ubiquity of phosphate ions in the cell but everyone skips over where their conjugate H+'s go. Obviously I can't take in all these phosphate ions without some sort of counterion, but to avoid killing myself with acidity I need some sort of base as well. I guess animals can avoid this problem by not synthesising phosphoric acid and instead taking inert phosphates in solution in food (with some sort of metal cation counterion -- sodium maybe?) but this implies the plants have already dealt with the acidity.

I know a lot of foods are in fact, kind of acidic -- fruits, milk and so on, but I thought that was due to weak organic acids, not because of the synthesis of semistrong phosphoric acid, and I guess plants would relegate the whole phosphorus-fixing thing to the roots, which then delegate that to symbiotic bacteria or fungus, but now they need to deal with the acidity. Where do all the H+'s go? Are they absorbed by organic bases and then replaced with counterions? I'm basically wondering because it seems to me you must have a base-synthesis reaction coupled with DNA synthesis (and an ATP synthesis), because the more phosphates you produce, the more H+'s you produce, predictably.

And on yeah, charge balance on DNA. Now that I think about it, how is the electrostatic repulsion between phosphate groups not stronger than the hydrogen bonding between DNA strands? John Riemann Soong (talk) 17:05, 12 September 2009 (UTC)
 * ?? The actual solids and liquids you ingest into your body are in rough electric balance, they only get charge-separated during metabolic processes - but the "other" charge always goes somewhere. Most body fluids seem to be mildly basic. For DNA charge balance, have you comsidered water solvation? Hydrogen bonding is important in the final structure of DNA. Solvation mediates the entire structure, and of course, in living systems nucleosomes do a lot of the organizing. I think that if you found DNA structural studies in aqueous vs. non-aqueous media, you would see a difference. Once again though, I got nuthin' for sources. Franamax (talk) 07:39, 13 September 2009 (UTC)
 * I mean naturally, but for the foods to be in electric balance, there must be some acid-base compensation going on ... maybe before the food was made (i.e. maybe it's at the level of phosphorus-fixing bacteria). John Riemann Soong (talk) 14:22, 13 September 2009 (UTC)

Astrophysics
In reading Numerical Methods for Astrophysics: An Introductio by Peter Bodeheimer, et.al., I ran across the term "mean particle separation". I am seeking a definition and perhaps some references to derivation of

n=l1/3

AWBest (talk) 19:22, 12 September 2009 (UTC)


 * You forgot to tell us what is 'l' in that equation. Even without that info I'm willing to guess that equation is the very answer to your question above, that is it is the definition of "mean particle separation". Dauto (talk) 20:25, 12 September 2009 (UTC)


 * If 'n' is a "separation" - then it's unit is length. So 'l' would have to have units of volume.  If 'n' is an average separation between particles - then 'l' would be something like the average volume occupied by a single particle.  In a few articles I skimmed after a Google search on "mean particle separation astrophysics", the equation n=r1/3 appears fairly often. SteveBaker (talk) 17:29, 13 September 2009 (UTC)


 * I would expect n to be a number density (e.g. 1 particle / cm³) and l to be a mean separation (e.g. 1 cm). Are you sure it's not n=l-1/3 (with a minus sign in the exponent)?  -- Coneslayer (talk) 17:14, 14 September 2009 (UTC)