Wikipedia:Reference desk/Archives/Science/2011 June 8

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June 8

Red/white poppy flowers

Recently in south east england I saw some poppies in someone's garden where the petals were both red and white, with the two colours irregularly mixed together. Does anyone know the species and or variety please? They were undoubtedly cultivated garden flowers and not the wild ones. Thanks 92.29.122.28 (talk) 00:25, 8 June 2011 (UTC)

Interesting. I wonder if it's a chimera (plant). StuRat (talk) 07:58, 8 June 2011 (UTC)

Googling for variegated poppy leads to a few photos. Also Shirley Poppy might be relevant. AndrewWTaylor (talk) 10:37, 8 June 2011 (UTC)

Thanks. I have not been able to find any photos of what they looked like, except this http://1.bp.blogspot.com/_lk-o4M_gWu4/TU99gCr0wUI/AAAAAAAAB5c/53BhPQ0jQ1k/s1600/5RCARN.jpg They were not picotee either. There was not any pink (like Shirly poppies), they looked as if red and white paint had been put in a pot and just stirred once or twice only. 92.28.242.181 (talk) 13:49, 8 June 2011 (UTC)

With the greatest respect, are you certain they were poppies? Richard Avery (talk) 14:07, 8 June 2011 (UTC)

Yes. Some searching around the internet reveals that there are a large number of little-known varieties of garden poppies, but I havnt found what I saw yet. 92.28.242.181 (talk) 15:36, 8 June 2011 (UTC)

Perhaps what I saw was a clump of the "Danish Flag" variety, viewed from the side. 2.101.15.113 (talk) 11:30, 9 June 2011 (UTC)

Stomach and food poisoning

I thought that bacteria, apart from Heliobacter, could not survive being in the stomach. If that is true, then how do people catch food poisoning? 92.29.122.28 (talk) 00:29, 8 June 2011 (UTC)

(a) The stomach is a harsh environment for bacteria but it doesn't infallibly kill them. (b) However, lots of food poisoning comes from toxins created by bacteria rather than from ingesting live bacteria; for example botulism, usually. Looie496 (talk) 00:37, 8 June 2011 (UTC)

Thanks, but news about the current E. coli food poisening scare in Germany suggests that the bacteria do infect people. 92.29.122.28 (talk) 00:39, 8 June 2011 (UTC)

Well yes, no one said otherwise Nil Einne (talk) 01:02, 8 June 2011 (UTC)

(e/c)There are many bacteria (including quite a lot of the more normal variants of E. coli) that routinely hang out in the gut. Once you get past the stomach it's quite habitable, and the stomach acid might kill 99.99% of the bacteria and still leave enough to establish an infection. EHEC inovlves an actual infection, so something has to survive, but it's more on the lines of toxicoinfection - the bacteria produces a toxin that causes the issue, the mass of bacteria isn't the problem. SDY (talk) 01:10, 8 June 2011 (UTC)

One method is endospores, which are the cellular equivalent of a bank vault. To quote the article, "Endospores can survive without nutrients. They are resistant to ultraviolet radiation, desiccation, high temperature, extreme freezing and chemical disinfectants. Common anti-bacterial agents that work by destroying vegetative cell walls do not affect endospores." Reputedly botulism endospores are killed by stomach acid,^[1] but Clostridium difficile (a diarrhea bug) is not.^[2] (But I don't get why people on Prilosec OTC don't get botulism from honey then...) Wnt (talk) 01:34, 8 June 2011 (UTC)

To the best of my knowledge, the stuff written above is correct, but a little bit beside the point of the question. Stomach acid is indeed a very harsh solution for anything to survive, which is why the dose makes the poison. A single E. coli has such little chance of making it through your stomach intact, that you might as well call it impossible, but if there are thousands or millions of bacteria present, even wiping out 99.999% might leave enough to start an infection. This is the nub of all food safety and food handling regulations: you can't completely eliminate the presence of germs, but by keeping food at a safe temperature, you can hopefully keep the bacterial load down to the point where normal human immuno-defences can do their part. Where you really run into trouble is where items not normally considered a potentially hazardous food get contaminated with something like E. coli, as in situations where untreated human or animal feces get into the irrigation system and essentially turn that tasty cucumber into a bomb filled with bacteria-laden water. Nobody worries about the temperature of a cucumber, you can't wash the bugs off, and few people routinely cook their cucumbers to a temperature high enough to kill of the germs (I'm using cucumber as an example here; it could be anything). Now you're ingesting thousands of bacteria, killing off 99% of them with your stomach acid and getting infected with the remainder. Matt Deres (talk) 14:05, 8 June 2011 (UTC)

Sorry, I didn't think about the EHEC outbreak when I wrote this. For E. coli, endospores are not an option; even so, it is said they can evolve resistance to stomach acid, and in fact, that the grain-fed diet of cows during "finishing" causes them to be much better at passing the consumer's stomach.^[3] I should say, though, that I don't really understand this argument - it implies that every strain of EHEC can evolve acid resistance or lose acid resistance over 5 days of feeding - yet the trait doesn't change while the bacterium is being tracked into a vegetable patch, picked, packed, shipped, and sitting on the supermarket shelf. But I suppose if any are resistant they stay in the vegetable population at some level... I don't know. But it's something of a political cause if you're interested. I should note, however, that sometimes I've gotten steaks produced in a more progressive way at a co-op store with a really strong "hay" taste, very much stronger than the mild flavor of venison, and I'm not sure grain feeding is all bad. Wnt (talk) 00:47, 9 June 2011 (UTC)

Gram-negative bacteria have a protective glycoprotein coating outside their cell walls, which makes them more resistant to extreme pH levels. -- An American ultranationalist 67.169.177.176 (talk) 23:58, 10 June 2011 (UTC)

Exercise and rest

If for example someone ran a marathon or half-marathon one day, how do sports coaches calculate how many days they should wait before doing the same thing again? I understand that it is possible to over-train. Thanks 92.29.122.28 (talk) 00:38, 8 June 2011 (UTC)

I believe these are mostly rules of thumb based on experience, not anything derived from science. Looie496 (talk) 01:10, 8 June 2011 (UTC)

Depends on the individual. For example, not many people could do this. -Atmoz (talk) 16:03, 8 June 2011 (UTC)

I vaguely recall hearing that the British army has changed its exercise/rest training schemes in recent years - does anyone know anything about that? Thanks 92.28.242.181 (talk) 13:51, 8 June 2011 (UTC)

But isn't that simply because the fitness of the general population in Britain has declined sharply? I've read that today's top 5% Cooper test scores for school children are below the average values recorded in the 1980s. Count Iblis (talk) 15:46, 8 June 2011 (UTC)

Really? I wonder if they changed the test or the way they scored it in the last 30 years because that would be quite the drop if true. Googlemeister (talk) 18:27, 8 June 2011 (UTC)

Are those tests taken by school children of approximately the same age? For example, I could imagine that in the 1980s most schoolchildren would take the test, whereas now many of the older children skip it with some excuses, so you only get results from the younger ones. – b_jonas 09:49, 9 June 2011 (UTC)

Yes, they compared children of the same age. I think this was mentioned a few years ago on BBC's Science in Action. Yesterday I tried to find some articles on this, but what I found was even more alarming. There is an Iranian study that measured fitness of young adults of about 22 years of age. Out of 250 males, the best result on the Cooper test was just 2300 meters. Now, 2300 meters is considered indicative of average fitness for someone of that age. In Britain, far more people are obese than in Iran, so you would expect even worse results. Count Iblis (talk) 15:12, 9 June 2011 (UTC)

I believe the army changed the length of the rest period - I do not remember the details. 92.24.128.171 (talk) 18:46, 8 June 2011 (UTC)

Presumably there are more then 100 countries with an "army" so we can't really help with the details. Googlemeister (talk) 14:42, 9 June 2011 (UTC)

Care to explain what you mean, or have you skipped the word "British" above? 92.24.129.68 (talk) 20:45, 9 June 2011 (UTC)

Animal Testing

The PETA article says that they "promote alternatives [to animal testing], including embryonic stem cell research and in vitro cell research". Would these be viable alternatives to animal testing? 65.92.5.252 (talk) 01:05, 8 June 2011 (UTC)

I think in general cell culture studies have a fairly poor reputation - different cell lines tend to do different things. In part that's because to this day people still fairly often use cell lines from tumors that have diverged greatly from the natural tissue they are supposed to represent - even having different karyotypes. I think that careful immortalization of cell lines with the smallest amount of genetic change possible might improve their usefulness a little.

That said, there's no substitute for the real animal - and the real animal is scarcely a substitute for the human. In vitro, dextran sulfate cures HIV. In vitro, immortality is easy, and gene therapy can target more than 90% of cells. There's not much you can do with pharmacokinetics and bioavailability in a tissue culture dish. And it makes poor practice for medical students learning surgery...

Of course, even animals can be a poor substitute for humans ... especially when studied by stupid people. See TGN1412, for example. That study would have been better off if they'd been allowed to go straight from the mouse to the human, because testing the human monoclonal antibody in a monkey made them think it had a low affinity ... when in fact there were a few 'minor' differences in the primate sequence. The results weren't pretty.

Much of this has more to do with "ethics", such as it is, than science. If we were serious about fighting disease - serious in the way that we've been about fighting wars - then we could line up a million test subjects, take every drug before it's ever entered the "pipeline", and test it on them flat out. Give the casualties medals, the survivors money and veteran health benefits, and jump medicine 15 years into the future - saving more lives than were lost. I don't know why that is only a noble thing to do when you're trying to kill people. Wnt (talk) 01:21, 8 June 2011 (UTC)

Not doing the basic research first would be ridiculous. The actual success rate for new chemical entities is dismal. The military equivalent would be like a human wave attack. Read up on WWI for how effective those are. For serious problems like HIV and malaria, it's not the lack of drugs that fails us, it's that the patients can't afford them, so mass suicide in the name of drug research isn't exactly justified. SDY (talk) 01:36, 8 June 2011 (UTC)

To be clear, I was not suggesting to try drugs before some rationale for activity had been devised. Nor trying them at once in large doses - rather, working up the dose gradually in a few subjects, like Sasha Shulgin's psychonauts. As for affordability, one aspect of a military-like campaign is that the drugs thus invented would be public property, and therefore quite inexpensive. Wnt (talk) 01:41, 8 June 2011 (UTC)

The way it's done currently is actually fairly sensible, though sometimes slow: they try and throw out the losers (the vast majority of candidates) in pre-clinical (mostly animal) testing, which is cheap compared to human testing because the standard of care is much lower (no one expects a $20,000 hospital stay for mice, except maybe PETA). Initial testing for things like genotoxicity (i.e. "is the drug mutagenic/carcinogenic?") are done in bacteria, which is dirt cheap (no one cares if you slaughter a million bacteria). Only 10-20% of drugs that enter clinical trials are approved, but most drugs don't make it to clinical trials at all, and approval isn't the final word on whether a drug is worth using. If the chances were higher, it might be worthwhile to go to human testing earlier, but the chances are really, really poor, and you'd just be throwing away people. PETA's point is that we're basically just throwing away animals with the same callous disregard. There are some ethical standards in animal testing, but they're mostly focused on easily avoided pain and suffering as well as ensuring the scientific validity of the study so that the deaths are not meaningless. As for "inexpensive" that a government pays for it doesn't make it free. SDY (talk) 07:03, 8 June 2011 (UTC)

With all forms of "intellectual property" there is a trade-off between the price and the number of copies sold. In the case of the newest pharmaceuticals, this is becoming rather absurd, with drugs routinely introduced that cost over $100,000 per patient, even though they are ordinary monoclonal antibodies any passable technician can make.

I don't deny the usefulness of screening in bacteria, cell culture and mice in many situations - it's more the bureaucratic requirement for a certain sequence of studies before a human test can be done. The primate studies bother me the most, but in general, once a compound has some promising indication, it would be nice to see if it can help those in great need. Instead companies are supposed to go through a gauntlet of intermediate tests, anteing up the venture capital ahead of time, paying the bureaucrats' salaries as they go, in the hope of a payout ten years later that depends more on marketing than medicine. There has to be a better way to do things. Wnt (talk) 08:05, 8 June 2011 (UTC)

If "any passable technician" can make them, why don't they? Also, the tests are there because the law demands it, and that obviously adds to the cost. But would you prefer the old (pre-regulation) way, where they just tested however they felt like doing it? ←Baseball Bugs ^{What's up, Doc?} carrots→ 12:14, 8 June 2011 (UTC)

That would probably infringe on the patent and get the tech sued. Googlemeister (talk) 13:37, 8 June 2011 (UTC)

Sorry, I let myself get carried away here - this isn't really the place for a lengthy political debate, and I'm getting too far off topic. Wnt (talk) 13:46, 8 June 2011 (UTC)

Regardless, as you suggested in your first statement, using less-effective tests just for the sake of "political correctness" towards lab animals is not necessarily the best approach. ←Baseball Bugs ^{What's up, Doc?} carrots→ 16:05, 8 June 2011 (UTC)

Four wheel drive..... and two wheel drive

Hi. I know that four whell drive vehicle is more powerful then two drive vehicle . but which one consumes more fuel two wheel drive or four wheel drive.......... I have doubt because I think both carry equal weight so both should consume equal fuel. — Preceding unsigned comment added by 220.225.96.217 (talk) 05:48, 8 June 2011 (UTC)

Four wheel drive vehicle has at least one extra differential and a set of driving axles to wheels. Thes increases both weight and mechanicla losses (friction), so it will consume more fuel. -Yyy (talk) 06:52, 8 June 2011 (UTC)

Agreed. Also, 4-wheel drive vehicles are not inherently more powerful than 2WD. However, in order to be able to still move at a reasonable speed despite the increase in weight and friction, they do tend to put more powerful engines in 4WD vehicles. Such engines are often diesels and/or mated to transmission geared lower, though, meaning 4WD vehicles typically have more towing and climbing torque, but less horsepower, and therefore don't typically accelerate very quickly. StuRat (talk) 07:51, 8 June 2011 (UTC)

A king cobra question

I saw a TV show recently about a king cobra tracking project. One finding that apparently wasn't expected (although I'm not sure why) was that males sometimes kill pregnant females. Unfortunately, having an attention span of a puppy, I may have missed the bit where they explained how a king cobra can kill a king cobra. Seems puzzling given that they use their venom to kill other snakes. What does this mean ? King cobra venom is toxic to king cobras ? King cobras are only immune (I assume they are immune) to their own venom ? It wasn't the venom that killed the females ? I can't find anything in our article or in google. Thoughts ? Sean.hoyland - talk 08:12, 8 June 2011 (UTC)

Why do you assume they are immune to their own poison ? If it gets into their blood stream, it's probably toxic to them, too. But heck, bacteria from our saliva would do bad things if large quantities of it got into our blood, too. StuRat (talk) 10:17, 8 June 2011 (UTC)

For no good reason really other than an assumption that there will be a fairly large quantity of venom left in their mouth after biting prey and some of it could get in their bloodstream through mouth cuts etc. I didn't realise but the Snake_venom#Immunity articles mentions an Egyptian banded cobra that accidentally bit itself. Sean.hoyland - talk 11:22, 8 June 2011 (UTC)

That's an interesting writeup, and it raises a question. Apparently, it's possible for a human to become immune to snake venom by presumably small innoculations over time and somehow the body builds a defense for it. But apparently this does not hold for poisons such as arsenic or mercury. Is that because the venom is organic and those poisons are not? Also, in The Princess Bride there's a key sequence in which the hero has "spent five years building up an immunity" to a (fictional) poison that is supposedly the most potent in the world. Is that actually possible for any poison, or only (maybe) if the poison is organic? ←Baseball Bugs ^{What's up, Doc?} carrots→ 12:09, 8 June 2011 (UTC)

I think it can work the other way too. I remember seeing something about a researcher who has been bitten by cobras a couple of times, survived because of antivenom but he's subsequently developed an allergy to the antivenom so that he now has the choice of dying from the next cobra bite or having a potentially lethal anaphylactic reaction to the antivenom. Marvelous. Sean.hoyland - talk 12:40, 8 June 2011 (UTC)

Sounds like he should take up a safer line of work, such as coal mining. ←Baseball Bugs ^{What's up, Doc?} carrots→ 12:43, 8 June 2011 (UTC)

People can build up an immunity to snake venom, just as they do to a virus, because it is an antigenic protein. While smaller chemical poisons might be bound as a hapten to some carrier protein to elicit an immune response (see cocaine vaccine), it would not readily occur naturally, and I haven't heard of it being done against an element. There are allergies against silver and nickel, and antibodies can be made against nickel-albumin.^PMID 118843 I wouldn't rule out the possibility of an immune response to arsenic or mercury but most people would dismiss this out of hand. Also, the immune system can't actually destroy an element with reactive oxygen species; I'm not sure if secretory IgA in the gut would tend to exclude it from being absorbed. Wnt (talk) 13:55, 8 June 2011 (UTC)

That makes total sense. Those venoms are proteins that can be broken down into simple, and harmless, elements; whereas arsenic and mercury can't be. I was in the neighborhood anyway. Thank you for the explanation. :) The "iocane" powder discussed in Princess Bride is fictitious, but if it were a protein, it could be possible to develop an immunity. ←Baseball Bugs ^{What's up, Doc?} carrots→ 16:01, 8 June 2011 (UTC)

The process you're referring to is mithridatism. Our article is a little short, but provides an overview. Matt Deres (talk) 17:38, 8 June 2011 (UTC)

Most stable elements aren't toxic in every molecule they form, so it would be possible to render such elements harmless by supplying the reactants and conditions needed to change it into into a benign molecule. However, I don't think this is a common response. StuRat (talk) 17:47, 8 June 2011 (UTC)

I thought Wnt's was a good answer, but is it really just immunology that's involved? (The Poison article could probably explain better how the body deals with poison). WikiDao ☯ 18:15, 8 June 2011 (UTC)

For snake venom, yes - for chemicals, probably not (see cytochrome P450). There might be compensating mechanisms for individual elements - for example, cadmium poisoning damages the kidneys in such a way that cadmium is excreted much more quickly.^[4] Wnt (talk) 21:15, 8 June 2011 (UTC)

How to compound risk factors

Smoking or LDL triple my chances of a heart attack, hypertension or diabetes double it, sedentary lifestyle increases it 12%, and obesity increases it by 62%. What if someone has several of these factors?

If these were independent variables in a statistics problem, you could take 2 x 3 x 1.12 x 1.62 and have your answer. But it being biology, these factors might synergize and become more dangerous together, or only the worst may apply, or they might even cancel each other out (wouldn't bet on it) - you'd need a study on people with the exact combination of factors you have to really know for sure. Wnt (talk) 14:03, 8 June 2011 (UTC)

The cumulative effect could be less than 2x3x1.12x1.62, without them cancelling. It seems to me these things might increase the risk through the same mechanism, in which case they could just add less if you already have a problem. Grandiose (me, talk, contribs) 14:24, 8 June 2011 (UTC)

I suppose that would be 3 x 3 x 2 x 2 x 1.12 x 1.62, if the variables are independent. 2.139.12.164 (talk) 14:32, 8 June 2011 (UTC)

Well, the question said "Smoking or LDL", rather than "and". Grandiose (me, talk, contribs) 14:44, 8 June 2011 (UTC)

Hmmm, you also need to take into account how the risks of dying from other diseases are affected. If these risks are increased by larger factors, then the risk of dying from a heart attack may actualy go down. Count Iblis (talk) 15:34, 8 June 2011 (UTC)

You also need to define clearly what you mean by phrases such as "the chances of a heart attack", "triple it" and "increase it by x%", otherwise you could end up with absurdities such as having a 250% chance of a heart attack. AndrewWTaylor (talk)

Note that several of those factors may lead to one another. For example, a sedentary lifestyle may lead to obesity which then leads to hypertension. So, the risk of a sedentary lifestyle may be largely due to it already including the things it typically causes. Therefore, there's not as much need to include them again, as separate factors. StuRat (talk) 17:29, 8 June 2011 (UTC)

I believe you would calculate the probability of surviving all the risk factors. I forget the name this has. If for example you had a 10% (0.1p) chance per year of being run over by a bus, and a 20% (0.2p) chance per year of choking on ice-cream, then if these were entirely independent you would have a 0.9 X 0.8 chance of not undergoing either of these. The combined risk factor per year would be 1 - (0.9 x 0.8) = 0.28

You would have to know the baseline risk before you could re-calculate your overall increased risk. For example if your risk of dying by being struck by lightning per year was 0.0000000001p, then even a hundred-fold increase in the risk would be nothing to worry about. This sort of thing is often discussed in pop science books. 92.24.128.171 (talk) 18:21, 8 June 2011 (UTC)

"...if these were entirely independent". As noted above, this being biology, they probably aren't. --Carnildo (talk) 00:11, 9 June 2011 (UTC)

gold nuggets

If you were to pour melted gold into a large quantity of water, would you end up with gold nuggets? Googlemeister (talk) 16:27, 8 June 2011 (UTC)

More or less, yes. If you mean to ask if these can be distinguished from those dug up or found in a river, then yes, I'm sure they could. For one thing, the purity of gold is likely to be higher. Also, there may be steam bubbles included in the gold this way. StuRat (talk) 16:48, 8 June 2011 (UTC)

I think it's more likely that you will get one hell of an explosion, which will send tiny droplets of gold flying around. The melting point of gold is 1064°C. Looie496 (talk) 17:19, 8 June 2011 (UTC)

A glob of molten gold is still pretty dense and probably pretty viscous. You'd get a lot of steam and so forth if you dropped a couple of pounds of molten gold into eg. the ocean, but I'm guessing it would remain one big glob as it sank and cooled. WikiDao ☯ 17:35, 8 June 2011 (UTC)

See this article, Molybdomancy, and substitute gold for lead. μηδείς (talk) 18:10, 8 June 2011 (UTC)

In Jules Verne's The Chase of the Golden Meteor, they got a large explosion, but most of the gold was apparently not molten, only very hot. – b_jonas 09:29, 9 June 2011 (UTC)

"Granules" is probably the more common term for what you'd end up with. Examples: [5][6]. They are made by gold refineries for use by jewellers. If my memory serves me correctly (many years ago I used to work at the Perth Mint), they are actually made by pouring molten gold into water. It looks like the Mint's refinery still does make them. Mitch Ames (talk) 14:13, 9 June 2011 (UTC)

conservation at the amino acid level is evil

I would like to express that 'conservation at the amino acid level is good' but without using the word 'good' which I think is inappropriate (it's neither good nor bad; it's just a fact). Is there a word I can directly replace it with? --129.215.5.255 (talk) 17:55, 8 June 2011 (UTC)

Well, the obvious suggestion is 'conservation at the amino acid level is a fact'. I haven't the slightest idea what any of this means, though. Looie496 (talk) 18:30, 8 June 2011 (UTC)

The OP is possibly referring to a situasjon where a gene is undergoing synonymous mutations. --NorwegianBlue ^talk 20:45, 8 June 2011 (UTC)

Conservation at the amino acid level reflects stabilizing selection that preserves the amino acid sequence, which indicates the decreased relative fitness of individuals bearing genes with many other possible amino acid sequences in the region. It can be measured in terms of the ratio between synonymous mutations and non-synonymous mutations within the coding sequence. Wnt (talk) 21:23, 8 June 2011 (UTC)

I don't know much about this question in particular, but I do have experience in science writing. Rather than use 'good', which implies a value judgment, you could use 'beneficial', which does not (i.e. assuming there is some quantifiable benefit to the organism (in terms of fitness) that it receives from 'conservation at the amino acid level'. The idea is, good or bad may vary, but 'benefit to the organism' has the potential to be made into a rigorous statement about the science that does not reflect the writer's bias. Does that make sense? SemanticMantis (talk) 22:01, 8 June 2011 (UTC)

This is briefly discussed at Conserved_sequence#Conserved_protein_sequences_and_structures. I usually think of "conservation at the amino acid level" in terms of comparative genomics, where comparisons of orthologous genes are made between different species, not within an individual. Perhaps the OP is trying to figure out how to express the degree of amino acid conservation, as in "there is perfect conservation at the amino acid level" etc. --- Medical geneticist (talk) 22:58, 8 June 2011 (UTC)

Indeed, I'm talking about the degree of conservation. However, it's not perfect; it's just well conserved. I'm looking for an alternative word to 'good' which carries no connotation of benefit etc. 129.215.47.59 (talk) 00:03, 9 June 2011 (UTC)

A "high level of conservation"? I disagree with SemanticMantis's proposal of "beneficial" as being a valueless term...if I'm a pathogen or somehow else engaged in microbial cat&mouse, I might be selected-against if my amino acid sequences are consistent. DMacks (talk) 00:09, 9 June 2011 (UTC)

I only meant that saying that a feature is beneficial to an organism is better than saying that it is 'good'. I don't think statements/claims such as 'property X increases the fitness of a population' are invoking any particular values. Obviously things that benefit one organism could do so to the detriment of others. Anyway it's a bit moot since I missed the OP's intent :) SemanticMantis (talk) 02:33, 9 June 2011 (UTC)

I'd say that (in general) it is going to be a good idea to ask "Why is it good?". For example, we start with a statement "Breathing is good.". Now question "Why is breathing good?" might get an answer "Breathing is good because lack of it will result in death after several minutes [and prevention of death is good]." (yes, more than one answer is possible). Now this answer has one part that concerns Biology: "lack of [breathing] will result in death after several minutes". Thus one just has to write it down while leaving the part concerning Philosophy out. I guess the same process should work here too. --Martynas Patasius (talk) 20:48, 9 June 2011 (UTC)

There's nothing really wrong with using good in this context, except that the advice above by people who think good means beneficial rather than strong scares me. Well-conserved is perfectly cromulent--just be aware that well is the adverbial form of the adjective good. You could simply say the mutation rate is low, which will be more clear to non-experts. μηδείς (talk) 15:22, 10 June 2011 (UTC)

I apologize for scaring you ;) Please see the wiktionary definition of 'good' [7]. There is no mention of 'strong', but that may fall under definition 9.Effective. Note definitions 10.Favourable, and 11.Beneficial. Part of why there is confusion here is that 'good' can mean many different things depending on context. SemanticMantis (talk) 15:57, 10 June 2011 (UTC)

No mention of strong? You might want to read On the Genealogy of Morals. μηδείς (talk) 16:08, 12 June 2011 (UTC)

explanation about metallic solids

Metallic solids are usually described as "positive ions in a sea of electrons" but is there any more detailed explanation. the band theory is great for explaining energy levels and conductivity (and I understand it quite well).But I want to have a more "visualised" imagination of metallic solids. and besides I want to be able to fit the orbital models of atoms to the metalic solids(somehow like the way molecular orbitals are explained) so can you help me? thanks a lot--Irrational number (talk) 18:58, 8 June 2011 (UTC)

Conceptually this is easy to do with graphite, where the p orbitals form a single conductive layer of molecular orbital (which can be written in the resonance notation as having an odd charge anywhere in a vast network of conjugated double bonds). But as for metals, well, it's not my field. When I did a search just now, I found a fascinating-looking work a person self-published on the web.^[8] He comes across as a bit of a kook, but I can't tell if he's the kind of kook who came up with a neat way to look at metals the way you want, or just a kook. He's definitely dedicated to his efforts, one way or the other! Wnt (talk) 21:35, 8 June 2011 (UTC)

The molecular orbital model doesn't work with metals. If you think about, say, the molecular orbital theory explanation for a simple molecule, like O₂, the usual explanation is that the atomic orbitals of the two oxygen atoms merge and reorganize into a set of molecular orbitals shared by the molecule as a whole. A different set of molecular orbitals would be organized around a molecule like, say, ozone (O₃). These molecular orbitals have well defined structures and are localized into (relatively simple) geometry. Even for a complex network solid, like diamond, molecular orbitals can still explain things like the bonding angles and distances between the atoms. In metallic bonding, however, the orbitals are all "delocalized", such that they do not occupy a discrete geometry around the atoms themselves. In metallic bonding, the orbitals form a contiuum of orbitals rather than individually identifyable orbitals; the result is the "sea of electrons" model. The reason we use that model to describe metallic bonding is because its the only one that works. Any bonding model that uses discrete orbitals between atoms, in defined locations, sizes, and shapes simply doesn't work for metallic bonding. The article Metallic bond is fairly in depth, I recommend reading it for more details. --Jayron32 00:52, 9 June 2011 (UTC)

its true that the "sea of eletron" model works but I can't combine my understanding of the band theory with model, specially when its emphasized that the transition of one electron from one band to the other doesn't mean that it actually "moves" somewhere else. well, my question is what DOES happen--95.82.51.37 (talk) 20:12, 9 June 2011 (UTC)

When electrons promote from one orbital to another in, say, the Bohr model, they don't physically move either. An electron is not a discrete particle like a little ball. What it does when it gets more energy is that it enters a higher energy state. This is exactly the same whether you are dealing with, say, excitation from the n=1 to n=4 energy level in hydrogen OR whether you are dealing with promoting up into the conduction band in the metallic bond "band" model. The electron doesn't physically move, it jumps to a higher energy state. We draw pictures of this on a graph or little "ring" diagram to make it visually obvious, but the distances on the graph or little ring diagram don't represent physical distances, they represent energy. --Jayron32 00:57, 10 June 2011 (UTC)

how does diamond crystal look on the surface?

The covalent bonds cannot simply go on for ever. I thought about it and I reached the answer "hexagonal with single bonds" is it correct?(probably not)--Irrational number (talk) 19:04, 8 June 2011 (UTC)

I don't believe it. I went to look this up, and according to Wikipedia, there's a whole nother kind of carbon called Lonsdaleite with a hexagonal matrix, which is harder than diamond in one plane but much softer in practice. You learn something new every day here! In general the structure of a face of diamond should depend on how it is cut, and of course whether the diamond has been exposed to hydrogen to form CH3s at the edge. There are lots of papers about the diamond (111) plane during vapor deposition of diamond, modeling the addition of atoms to the structure, but I can't read them here, and they don't give away any secrets in their abstracts. Wnt (talk) 21:43, 8 June 2011 (UTC)

The covalent network in a diamond is generally terminated with hydrogen atoms at the surfaces. The article and section Material_properties_of_diamond#Hardness_and_crystal_structure mentions this briefly; you can also substitute the hydrogens for other terminators under extreme conditions; its possible to replace the hydrogens with hydroxyl groups instead, which changes the surface properties of the diamond. --Jayron32 00:41, 9 June 2011 (UTC)

Which way around is the Moon in the sky?

In regard to my earlier question, surely the Moon cannot always seem to be the same way around in the sky regardless of where you are on the Earth and how you look at it? Because otherwise, "north" and "south" would be fundamental laws of physics and not just something we humans arbitrarily assigned one way out of a possible two ways. What does the Moon's orientation in the sky depend on? JIP | Talk 19:15, 8 June 2011 (UTC)

It is true, the moon is not always in the exact same orientation in the sky, but it is pretty close; the moon is tidally locked with the earth, so the same side is always facing us when we look up at it (this isn't entirely true, see Libration, but it is essentially true). If you stand on an astronomical body and designate one pole as "North" (as we have done with the Moon, it is in the same direction as Earth's north pole), then it follows that if you face "North" on the surface of said body, the direction directly to your left will be "West". Since the moon is essentially oriented the same way in the sky (except for minor changes from the aforementioned librations and variations in your viewing latitude on Earth), if you are looking up and facing North, then "West" on the moon will be to your RIGHT, since you are standing upside-down relative to the Moon's surface.

Sorry if I'm repeating stuff that has already been said, but I haven't read the whole thread above. Hope I have given a sufficient answer. -RunningOnBrains^(talk) 20:03, 8 June 2011 (UTC)

I'm not sure I understood your answer fully, or you understood my question fully. I will try to phrase my question more specifically. Suppose we define "north" on the Moon as the direction that the pole facing the same way as the Earth's North Pole (near Scandinavia, not near Australia) is facing. Is it possible to look at the Moon in one place on the Earth and see north pointing up (away from the horizon) and look at in another place on the Earth and see north pointing down (towards the horizon)? Does this depend on the place or the orientation, or both? (After edit conflict: It looks like Tango below has answered my question. I have never been in the southern hemisphere.) JIP | Talk 20:11, 8 June 2011 (UTC)

The simple answer is usually to think about the most extreme cases: If you are standing on Earth's North Pole, you will see the Moon's North Pole pointing up, whereas if you stood on Earth's South Pole you would see the Moon's North Pole pointing down. The tilt of the Moon relative to Earth's horizon is a simple function of latitude (again, roughly, ignoring minor factors). -RunningOnBrains^(talk) 00:21, 9 June 2011 (UTC)

It depends on your latitude. The most obvious example of this is comparing a crescent moon viewed from, say, London with it viewed from near the equator. Near the equator, the crescent moon looks like it is lying down. Viewed from Sydney, on the other hand, it would look upside-down compared to the moon Londoners are used to. --Tango (talk) 20:06, 8 June 2011 (UTC)

Compare these two photos: A, taken in Florida (about 25 degrees north) with B, taken in Sydney (about 33 degrees south). [Use this atlas if you need more guidance] Compare the position of Tycho, the light area with the prominent radiating ejecta. In A Tycho is at about 7 o'clock; in B Tycho is way up at about 2 o'clock. -- Finlay McWalter ☻ Talk 21:55, 8 June 2011 (UTC)

Our conception of "east" and "west" are also different between the Earth and the celestial coordinates. ~AH1 ^(discuss!) 15:41, 11 June 2011 (UTC)

Solder

I've got the garden variety solder that is sold a Radio Shack for electronics. Would this solder be appropriate for soldering a connection that will carry 2.5A 120V?

Yes, it will work. However if you are going to solder steel (which is likely for those values), you are going to need to use a special acid flux in order to get the solder to stick to it. The flux in the core of garden variety solder only works properly for silver, gold, and tin. Copper also requires a special flux, but a different one. This is important -- you can cause a lot of trouble for yourself by not using the right flux. Looie496 (talk) 21:37, 8 June 2011 (UTC)

Misinformation alert with respect to the previous post. Why would anyone use steel to conduct 2.5 amps? Copper commonly conducts orders of magnitude more current than that in power conductors. Rosin core solder is commonly used for copper connections. Traditional rosin core electronics solder was a mixture of tin and lead, with rosin as a flux to prevent oxidation of the solder copper. The claim that "garden variety solder only works properly for silver, gold and tin" is nonsense. I agree that the proper flux is important. Rosin core is for electronics, acid core is for plumbing. Edison (talk) 04:23, 9 June 2011 (UTC)

My assumption was that if you are dealing with 120 V, you are probably trying to solder wires to wires or wires to posts of some sort. Wires are usually made of copper or steel; posts can be made of anything. Looie496 (talk) 07:01, 9 June 2011 (UTC)

The voltage 120V is lethal and you must take proper precautions, preferably with advice from someone experienced. The article Solder tells you much more than you probably need to know. Look closely at the illustrated solder joint of a red wire to a circuit board because all the joints show proper "wetting" of the underlying metal by the molten solder. Solder wire for electronics typically has flux in core(s) in the wire. "Ersin Multicore" is a common brand that will wet well to copper or previously tinned copper wires (but soldering aluminium is difficult). Some usual advice is to apply the solder to the parts being soldered, not directly to the soldering iron. Gain some experience in making bad "dry" solder joints caused by too low iron temperature, or parts moved while the solder cooled, to recognize the kind of joint to avoid. Another rule is that solder alone must not hold the parts together mechanically. Cuddlyable3 (talk) 22:36, 8 June 2011 (UTC)

Regulations vary with region, but in general it is not advisable to make high-voltage, high current connections with solder because a high current could melt the solder leaving a loose high-voltage wire. Use a compression fixing instead for safety and to keep within regulations. I have no idea what garden solder is, but I would have thought that any solder sold by Radio Shack would have a flux designed for copper, definitely not silver or gold! In the UK, 240v wiring is almost always copper, but I don't know if this is true for 120v wire in the USA. Dbfirs 07:22, 9 June 2011 (UTC)

Garden variety solder just means typical or common solder. Googlemeister (talk) 14:26, 9 June 2011 (UTC)

wikt:garden variety DMacks (talk) 21:35, 9 June 2011 (UTC)

Yes, I was only pretending to misunderstand, but plumbers and silversmiths would have different gardens! Dbfirs 09:20, 11 June 2011 (UTC)

Also, for connecting wires for that voltage, you usually want to use Screw terminals instead of soldering. The disadvantage of soldering is that sometimes all the current has to flow through the solder alloy, which has too high a resistance and so will overheat, which can cause the soldering to break at best, and a fire at worst. – b_jonas 09:17, 9 June 2011 (UTC) (Ps. ah, apparently User:Dbfirs has already said this above. Sorry. – b_jonas 09:18, 9 June 2011 (UTC))

That's OK, you said it more clearly, though I was intending to include other Electrical connectors that are sometimes also used. Dbfirs 09:25, 11 June 2011 (UTC)

Soldering instructions I've seen in Heathkit manuals and the like emphasized making a solid mechanical connection before soldering. I agree that there are other good means for high voltage/high current connections. There are crimp connectors which cannot loosen in the way screw terminals do. But a proper solder connection makes a stable low resistance connection. Here is a reference to a book on soldering which says typically the solder joints add little resistance to an electronic assembly. A solder joint can fail if the load cycles up and down while there is mechanical strain on the joint. Edison (talk) 18:34, 9 June 2011 (UTC)

The given current and voltage values 2.5A and 120V are conditions that affect the cross-sectional area of the conductors to be joined, and the insulation needed around the conductors respectively. They have practically nothing to do with the suitability of the solder. Cuddlyable3 (talk) 21:28, 9 June 2011 (UTC)

True, but they do affect the decision about whether solder on its own makes an appropriate choice. Dbfirs 09:31, 11 June 2011 (UTC)

Thank you everyone! In case you are interested, I'm swapping out a broken panel mounted Variac. One of the connecting wires appears to be steel and one is copper (this equipment is quite old). ike9898 (talk) 16:44, 10 June 2011 (UTC)

anaphyalactic shock

Is the inability to breathe the only thing that would cause anaphyalactic shock to kill a person? For instance, if a person was in a hospital and had one of those breathing machines hooked up so that their airway stayed open, is there something else that would kill them? Googlemeister (talk) 21:13, 8 June 2011 (UTC)

Anaphylaxis#Anaphylactic shock says it also causes a drop in blood pressure. That could kill you too. --Tango (talk) 21:51, 8 June 2011 (UTC)

The "signs and symptoms" part of that same section also lists a couple of other options. Even with an open airway, aspiration of vomit could kill a person, and myocardial infarction would also pose a danger. 98.94.135.184 (talk) 22:21, 8 June 2011 (UTC)

nuclear power reactor

What is the smallest nuclear power reactor on a naval vessel (a nuclear wessel as it were) and what does the reactor weigh? Googlemeister (talk) 21:17, 8 June 2011 (UTC)

You may also be interested in nuclear power used in space satellites, such as Systems for Nuclear Auxiliary Power. 92.28.247.193 (talk) 23:36, 8 June 2011 (UTC)

NR-1 Deep Submergence Craft was the smallest nuclear submarine that I know of, but our article gives no details of the reactor. -- 110.49.249.59 (talk) 23:56, 8 June 2011 (UTC)

Note that our article Nuclear marine propulsion states The smallest nuclear submarines to date are the 2,700 tonne French Rubis class submarine attack submarines. and makes no mention of the long serving but never officially named or commissioned NR-1. Rubis class submarines are powered by the 48MW K48 PWR, but we lack an article on the K48 reactor. -- 110.49.249.59 (talk) 00:08, 9 June 2011 (UTC)

Also note that our article List of United States Naval reactors lists:

• NR-1 reactor

• one-of-a-kind reactor built for the U.S. Navy research submarine NR-1

but the link is to the article on the sub itself.

Haze Gray's entry on NR-1 states that it was "initially constructed to evaluate small nuclear power plants", but again, there is no details of the reactor beyond stating that, "most of the hull [was] consumed by the reactor". So, the best answer I can give to the OP's question of "what does the reactor weigh?" is "under 400 tons", and even if details of NR-1 reactor were available, the answer would vary considerably on whether the weight of just the fully fueled reactor vessel was given, or if the weight included the entire plant, including the pumps, steam generator, turbine, control stations, shielding, structural substrate, etc. For the latter case, I suspect that you are talking about 100 - 200 tons. For the former case, I haven't been able to find weights of other naval nuclear reactor cores to form a basis for comparison. -- 110.49.249.59 (talk) 00:45, 9 June 2011 (UTC)

Just to clear things up, there is a difference between an nuclear battery and a nuclear reactor. Plasmic Physics (talk) 07:18, 9 June 2011 (UTC)

Not sure if this is of use to you, but we do have an article on List of small nuclear reactor designs. --Mr.98 (talk) 13:44, 9 June 2011 (UTC)

"The design of an idiot"

G'day mates :) </offensive Aussi impersonation> I was watching an interview with noted biologist Richard Dawkins, and it quoted him as saying that the design of the eye, with the nerve "wiring" on the outside of the photoreceptors, can be traced evolutionarily, but if it were just to be created directly from scratch, as by a designer or engineer, to put them on the outside would be "the design of an idiot". This piqued my curiosity: Are there any other examples of features, human or otherwise, whose construction makes sense if understood from an historical and evolutionary perspective, but which make no sense if thought of as created suddenly and from scratch? Thanks. 72.128.95.0 (talk) 23:40, 8 June 2011 (UTC)

Oh Lord, there are vast numbers of examples. Microsoft Windows and English Common law, to pick two at random. Our article on the Argument from poor design gives a number of examples from evolutionary biology. Looie496 (talk) 23:55, 8 June 2011 (UTC)

Not to mention the appendix. Why would God design us specifically with a useless flap in our intestines that gets easily infected? If He wanted to smite someone, I could think of other, more efficient ways.-RunningOnBrains^(talk) 00:24, 9 June 2011 (UTC)

Someone once remarked (somewhat famously) of the platypus that it looked as though it was cobbled together from spare parts. --Jayron32 00:34, 9 June 2011 (UTC)

And the old joke that a camel looks like "a horse designed by a committee". (Keep in mind that Genesis says, "Let us make man in our image." That would be the Elohim Committee.) ←Baseball Bugs ^{What's up, Doc?} carrots→ 13:46, 10 June 2011 (UTC)

Are you thinking of The Last Continent? Hans Adler 07:35, 10 June 2011 (UTC)

Two specific examples I like are the food pipe and wind pipe being the same thing, leading to thousands of people choking to death every year merely by eating. The second is Recurrent_laryngeal_nerve#Evidence_of_evolution. Vespine (talk) 01:21, 10 June 2011 (UTC) sorry was not logged in. 00:46, 9 June 2011 (UTC)

If you've ever had your nose so clogged up that you couldn't breathe but through your mouth, you wouldn't say that. Two large holes, one to breathe through, and one to eat and drink with, would be a waste of space. – b_jonas 09:08, 9 June 2011 (UTC)

Au contraire, lots of animals have evolved mutually exclusive breathing and eating systems. See gills and spiracles. --Jayron32 00:52, 10 June 2011 (UTC)

You don't need God as an excuse for an "idiot design". Where I live there are many buildings that have gas (methane gas) heating. It is implemented where once the coal stove was. The coal stove was fed in the evening and had solid, heat storing stones about it, so it could store the heat until morning, when it would be fed again. With gas, that heat storing and thus heat shielding oven is just an idiotic design. When you turn on the stove at full power, most of the heat goes up the chimney. At the time the gas heating was to replace the coal oven, gas was cheap and no one bothered for a few extra pence up the chimney. So at that time it was not at all idiotic to do it that way instead of bulldozing down the house and rebuild it completely. If you think about it, you will find plenty of examples like that in completely different context. 5BYv8cUJ (talk) 01:07, 9 June 2011 (UTC)

I think you've misunderstood what Dawkins was saying. He's saying that the fact that biology is full of "idiot design" probably implies that the structures you see are evolutionary in nature rather than divinely engineered. (Or you end up in the uncomfortable position of saying that God designed it, but was a bad designer. Which neither Dawkins nor the Intelligent Design people he is arguing against support.) --Mr.98 (talk) 01:14, 9 June 2011 (UTC)

Note that "evolution" isn't limited to biological evolution. Many other things evolve, such as cities. And, just like biological evolution, the results are often sub-optimal, compared to if the city had been well planned from the start. Thus, we can get a series of road grids which are at different angles and/or with different spacing within one city (those were probably separate towns when the grids originated). StuRat (talk) 01:36, 9 June 2011 (UTC)

Reverting to biological structures, an excellent example is the Recurrent laryngeal nerve which, because of gradual evolutionary morphological changes from a common fish ancestor in which it followed a straight-line path, makes an "unnecessary" diversion of many inches in humans and around 15 feet in the giraffe. This topic was well explored in Series 1, Episode 4 of the documentary series Inside Nature's Giants, if you can get access to it. {The poster formerly known as 87.81.230.195} 90.201.110.36 (talk) 09:58, 9 June 2011 (UTC)

The Vas deferens loops around the pubic bone instead of taking the direct route. 2.101.15.113 (talk) 13:04, 9 June 2011 (UTC)

If I were God I wouldn't have put the points of maximum pleasure so close to the points of waste disposal. Caesar's Daddy (talk) 13:44, 9 June 2011 (UTC)

The absence of wheels which could have been a more efficient way for land animals to move around than legs. Cuddlyable3 (talk) 21:16, 9 June 2011 (UTC)

Wheels would make stairs a bit tricky though ;-) Alansplodge (talk) 18:18, 10 June 2011 (UTC)

Having humans being able to re-grow lost body parts would have been useful, instead of only allowing animals like the salamander that privelidge. 92.24.185.180 (talk) 21:31, 9 June 2011 (UTC)

Another interesting subject I discovered recently is Genetic sexual attraction which also can not be explained if the human race were created, but makes perfect sense if we evolved. Vespine (talk) 06:12, 10 June 2011 (UTC)

Belief in God and belief in evolution are not mutually exclusive. It depends on whether you consider God to be merely a "creator" or also a "tinkerer". On the other hand, there is this cogent comment in Love and Death: "I wouldn't say that God is evil. I think the worst you can say about Him is that He's an underachiever." ←Baseball Bugs ^{What's up, Doc?} carrots→ 13:48, 10 June 2011 (UTC)