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February 11

Why people with hypoxemia get blue color (cyanosis) on their skin?

Why people with hypoxemia get blue color (cyanosis) on their skin? Iv'e done googling but I got confusing answers. One article claims that it's because of the deoxyhemoglobin and another one claims that it's not the reason. In fact, I would like to know a simple answer for why deoxigenation causes to appearance of bluish skin in a way that it looks like as if the blood is blue (obviously, I absolutely know that the blood is not really blue but I do understand generally that there is an issue of illusion by the wavelengths and light absorption. It's not clear to me especially with thr relation to the ). 93.126.88.30 (talk) 00:11, 11 February 2017 (UTC)

The two articles you link to are about different phenomena. The first is about cyanosis (bluish skin), the second is about why veins seem blue - a related but not identical situation. I think you'll find the deoxyhemoglobin explanation is the usual explanation for cyanosis, though you may find other viewpoints. You can find various articles that are somewhat pertinent by googling the phrase "Mechanism of cyanosis". (rather than "cause of cyanosis, which leads to differential diagnoses). Since there are different causes of cyanosis working via different mechanisms, no explanation is going to be simple. - Nunh-huh 00:58, 11 February 2017 (UTC)

• Well oxygenated blood is bright red, while poorly oxygenated blood is rather dark. If you consider that red and cyan are on opposite sides of the color wheel, a lack of red where expected would cause a relatively darker or cyanic look. Of course there are all sorts of color wheels, and different types of pigmentation, in case anyone wants to nitpick. But the RGB color wheel is quite pretty. Exposing old bluish sealed ground beef to the air will turn it red again if it has not gone totally off. μηδείς (talk) 03:53, 11 February 2017 (UTC)

Aircraft tendency to roll?

In an episode of Mayday, it was mentioned that the accident aircraft in that episode had a natural tendency to roll to the right, and that it was typical for older aircraft (this particular aircraft was 17-18 years old at the time of the accident) not to fly level by default. Do aircraft acquire a natural tendency to roll to one side or another over time, or is this tendency present from the moment they enter into service? 173.52.236.173 (talk) 04:53, 11 February 2017 (UTC)

I've never heard of that, and can't find anything from quick searching. Do you know which episode it was in? Someguy1221 (talk) 05:04, 11 February 2017 (UTC)

The subject accident is Adam Air Flight 574. 173.52.236.173 (talk) 05:19, 11 February 2017 (UTC)

Our article mentions an uncorrected roll, but nothing about the aircraft's age causing it. The rudders on many 737s had a tendency to turn on their own, inducing both a yaw and a roll [1], so it might have been true in the sense that "737s built in this particular time window have a tendency to roll". No idea really if that's what the people in that episode were talking about. Someguy1221 (talk) 05:30, 11 February 2017 (UTC)

Among the many non-ideal effects that can cause uncommanded roll, p-factor is the first that comes to my mind... (it's more of an uncommanded yaw than a roll); but I'll have to take a closer look at the source material to see whether this specific effect is relevant to the example in this question. Nimur (talk) 08:02, 11 February 2017 (UTC)

Not relevant to the example in question -- jets don't have P-factor. 2601:646:8E01:7E0B:F88D:DE34:7772:8E5B (talk) 10:14, 11 February 2017 (UTC)

Indeed, very true - I ought not even have mentioned that, as p-factor is not specifically relevant here! I apologize for jumping in with an answer before fully briefing myself on the information pertinent to this question.

It looks like the aircraft in the OP's event was a 737. If you direct your search for the terms "737 uncommanded roll" you'll find a lot of coverage, e.g. this 1996 article in Aviation Week: NTSB Probes 737 Uncommanded Roll. That event was related to the yaw damper. In layman's terms, a yaw damper is sort of like a part of the "autopilot" that is meant to help keep the airplane stable; but it is in fact a separate "line replaceable unit" - a separate subsystem - that can drive the control surfaces of the very complicated aircraft. In the FAA's detailed supplemental report on USAir Flight 427, there is a lot of discussion about how an engineering malfunction and a defective design may have contributed to uncommanded - or even reverse-commanded - flight control deflection, in early versions of the Boeing 737.

Nimur (talk) 17:31, 11 February 2017 (UTC)

At least some Boeing 737's used turbofan engines. Would that introduce gyroscopic effects ? If so, that would tend to resist any change in direction, although presumably not enough to be a problem, or they wouldn't use that design. StuRat (talk) 00:53, 12 February 2017 (UTC)

Aren't all 737 equipped with turbofans? the article we have does say that. Besides, I wonder if the gyroscopic effect affects roll, since the axes of rotation are parallel to the roll axis? They would have effect on pitch and yaw though. Rmvandijk (talk) 15:00, 15 February 2017 (UTC)

Why do boys like girls long before spermarche?

Why would evolution favor that? This seems the complete opposite of the male evolutionary motif, shouldn't the average age of spermarche be 10? Why make us want girls at an age when they'll be absolutely no reproducing? Sagittarian Milky Way (talk) 14:23, 11 February 2017 (UTC)

I don't think you could say that evolution favors that. The mechanisms of sexual attraction are probably in place separately from the ability to ejaculate, and timewise they approximate one another. If perhaps sexual attraction precedes the capacity to produce offspring, there doesn't seem to me to be any great cost associated with that amorousness. Bus stop (talk) 14:41, 11 February 2017 (UTC)

Who says they do? ←Baseball Bugs ^{What's up, Doc?} carrots→ 15:04, 11 February 2017 (UTC)

Spermarche says 11-15 for an average of 13. Sagittarian Milky Way (talk) 15:16, 11 February 2017 (UTC)

BB's question is legitimate - at what age do boys typically start feeling sexual attraction towards females? Personally, I didn't really experience it until the beginning of puberty (when testosterone levels begin to rise), but that's only anecdotal. Does the research support the OP's contention, that male attraction to females typically pre-dates spermarche? Eliyohub (talk) 15:58, 11 February 2017 (UTC)

The gap was almost 4 years for me. That's like half of adolescence. Sagittarian Milky Way (talk) 16:26, 11 February 2017 (UTC)

Even if it did, why should we find this anomalous? Is there an outsized biological cost to sexual attraction preceding actual ability to reproduce? If so, what would it be? I don't think there is any cost, but maybe I'm overlooking something. Bus stop (talk) 16:14, 11 February 2017 (UTC)

I'm not sure how good it is but this source suggests around 9-10 is common (it includes a ref) and it appears to coincide withoccurs after adrenarche (also includes a ref) [2]. Edit I should have said occurs after adrenarche which is what the book says, now corrected. As far as I can see it's not implying there's necessarily a connection, it only deals a small amount with the science anyway. I'd note from the time frames mentioned for adrenarche, it may be at least 1 year and maybe up to 3 after depending on various things including I suspect how exactly you define the start. Nil Einne (talk) 03:16, 13 February 2017 (UTC)

Note that children practice a wide range of adult behavior, such as playing with plastic tools and changing diapers on dolls. In this context, it's just one more thing to practice. Also, since humans are social animals, establishing relationships with the opposite sex early on might help to maintain those relationships until after puberty. StuRat (talk) 16:44, 11 February 2017 (UTC)

Perhaps this is a preparatory behaviour. Many predatory non-human animals perform substantial amounts of play behaviour which is considered to be preparation for hunting and catching prey when they are older. This happens at an age when they are still getting all their food requirements from their mum and/or dad. DrChrissy ^(talk) 17:05, 11 February 2017 (UTC)

Following on from SR & DrChrissy. Think it is simple. Evolution encouraged our ancient ancestors to start looking for suitable mates and establish a strong a bond before breeding begins. Even animals exhibit and practice courtship behaviour as juveniles. Playing with dolls is a cultural thing (which is learnt). Getting interested in the opposite sex as possible future dependable partner is more instinctive driven. Boys are 'instinctively' attracted to girls with good figures because it is advertising that she is in good breeding condition and girls are 'instinctive' attracted to boys that demonstrate (through actions and behaviour) that they will be able to provide and bring home the bacon, put bread on the table to feed the family and protect them from harm. Behaviour after that bond is created becomes X rated so can't comment.--Aspro (talk) 17:26, 11 February 2017 (UTC)

Oh Gosh. Hope I haven't taken the love & romance out of all this! Use common sense by all-means but follow your instincts and bond. Beware of one's closest friends and confidants – it is also in their selfish genes to 'subconsciously' bugger a relationship up for you with their well-meant but stupid advice. This is especially important if having attended a single gender school. Ones own sex can be your worst enemies when it comes to love and romance (both of which should be and remain private).--Aspro (talk) 17:55, 11 February 2017 (UTC)

If the sperm production preceded the amorous attraction one could argue that there is a biological cost in sperm production. But as it is the other way around the question is what cost is there in amorous attraction? Bus stop (talk) 17:38, 11 February 2017 (UTC)

Can't stop thinking about her, fail to notice a lion and get eaten, falling in love takes an inordinate amount of time away from learning hunting, will before a way decreases the average number of STD-less offspring... Sagittarian Milky Way (talk) 18:26, 11 February 2017 (UTC)

For a start there is the cost of diapers , medical bills, lawyers fees to get the teenage father to accept some responsibility. Possible failure for the young mother to complete her high school education... The list of costs go on and on. In more the more primitive societies of ancient ancestors it was a death sentence for the new born. --Aspro (talk) 18:16, 11 February 2017 (UTC)

I think we might be considering this in a too-modern human perspective. Back in the good old days, I think if I had been 10-13 and fancying a a young Elle MacPherson, I would have still run away like stuff off a chrome shovel if I saw an approaching lion. Who knows, I might have pushed Ell in the way of the lion to increase my chances of surviving and subsequently mating! Our motivations are quite primeval!DrChrissy ^(talk) 18:57, 11 February 2017 (UTC)

Did people that age in lion country usually carry an anti-lion device? (pointy stick?) Sagittarian Milky Way (talk) 19:13, 11 February 2017 (UTC)

I would imagine so, and very probably a couple of rocks and perhaps a slingshot-type device - but the Fight-or-flight response would have kicked in and throwing Elle to the lion and running like hell might have been the behavioural final common path.[3] DrChrissy ^(talk) 20:26, 11 February 2017 (UTC)

Amorous feelings do not impact upon the chances of survival or eventual reproduction. The question asks why would evolution favor boys liking girls before spermarche? Evolution does not favor boys liking girls before spermarche. The observed phenomenon is irrelevant to evolution. Unless of course someone can actually name a consequence, such as a disadvantage in survival or eventual reproduction, associated with early-onset amorousness. Bus stop (talk) 20:41, 11 February 2017 (UTC)

But I have suggested a potential advantage (preparation for adult life) and Sagittarian Milky Way has suggested potential disadvantages (getting distracted and thereby eaten by a lion). Admittedly, these are both OR, but they are both plausible. Note that the cost of having a motivation must be incredibly small - it is the behaviour of acting upon the motivation which is likely to have an effect on fitness. DrChrissy ^(talk) 20:49, 11 February 2017 (UTC)

Hence the observed phenomenon is irrelevant to evolution, because an advantage and a disadvantage would cancel one another out. Bus stop (talk) 21:36, 11 February 2017 (UTC)

Absolutely not - it would depend on the relative strengths of the advantages and disadvantages to fitness. DrChrissy ^(talk) 21:50, 11 February 2017 (UTC)

Both of which you concede are original research. Bus stop (talk) 22:00, 11 February 2017 (UTC)

Yes, I stated that - did you read my post? DrChrissy ^(talk) 22:31, 11 February 2017 (UTC)

In my opinion there is a distinct difference between something physical (the development of gametes) and something behavioral (sexual attraction). Evolution has to carefully allocate precious biological resources for one purpose or another. But evolution can afford to play much more fast and loose with mere behavior that in any case doesn't lead to pregnancy hence the passing on of traits. Bus stop (talk) 03:44, 12 February 2017 (UTC)

You are speaking as if you believe evolution has a master-plan or a template it is working toward. This is not the case. Evolution is what we see as the result of random mutations (which affect both behavioural and physiological attribute). Furthermore, evolution has not finished...it is an ongoing process. DrChrissy ^(talk) 18:24, 12 February 2017 (UTC)

What evidences that I am "speaking as if [I] believe evolution has a master-plan or a template it is working toward"? Is there something I've said that suggests this? Bus stop (talk) 19:52, 12 February 2017 (UTC)

Your sentence "Evolution has to carefully allocate precious biological resources for one purpose or another." DrChrissy ^(talk) 19:57, 12 February 2017 (UTC)

A living organism has many competing demands. Developing viable gametes is just one of those many competing demands. Many systems are developing during a time of prepubescence. Assuming that sexual attraction precedes by a few years the development of viable gametes, this is somewhat inconsequential in determining the course evolution takes. Biological assets diverted to gamete production are not available for other pressing needs. But the mere attraction for the opposite gender in the absence of any ability to actually reproduce does not factor into evolutionary pressures. For one thing, behavior does not in any obvious way detract from the body's various developing systems. But of additional importance is that such behavior does not pass on genetic material due to the fact that pregnancy does not take place. Bus stop (talk) 20:30, 12 February 2017 (UTC)

What you have written is OR. I say that not in a derogatory way, but recognising it for what it is...because I am also about to write OR. You stated But the mere attraction for the opposite gender in the absence of any ability to actually reproduce does not factor into evolutionary pressures. What about this consideration. What if my becoming attracted to girls at a younger age makes me interact with them more at that age, and then when I become sexually mature I am more able to attract mates as a consequence of this prepubescent motivation and behaviour. That certainly would factor into evolutionary pressures. DrChrissy ^(talk) 20:48, 12 February 2017 (UTC)

One possible evolutionary pressure against this is if it spreads diseases, like mononucleosis and oral herpes, which decrease the chances of passing on your genes. StuRat (talk) 21:06, 12 February 2017 (UTC)

I was actually thinking of non-sexual interactions such as learning courtship behaviours not leading to mating, but you are correct if sexual interaction occurs. DrChrissy ^(talk) 21:14, 12 February 2017 (UTC)

You can spin any tale. You can argue that prepubescent sexual behavior favors or disadvantages the later passing on of genetic material. But you cannot argue, and you have not argued, that the development of viable gametes does not figure prominently in the evolutionary directions that the species takes. What we know is that the point in time that the ability to reproduce has a clear and direct influence on the evolutionary directions that the species takes. But you cannot make the same argument with nearly the same degree of assuredness that the display of non-viable (for reproduction) sexuality figures into the direction that evolution takes the species with each succeeding generation. One thing is known, the other thing is merely hypothesized about. It is not a matter of whether the "research" is "original" or not. The realm of the physical is different from the realm of the behavioral. Materials are costly. Behavior may or may not provide an evolutionary pressure. The particular behavior under consideration does not, in and of itself, result in the passing on, of genetic material. Thus you have to spin a tall tale to argue that prepubescent sexual attraction plays a part in the direction taken in the evolution of the species. Bus stop (talk) 21:19, 12 February 2017 (UTC)

Wow! This is beginning to feel like an attacking rant. I have been honest and open where I have posted OR mainly because I am very mindful this is a reference desk, so your calling these "tall tales" is rather objectionable. They are scientifically plausible ideas. Early experience in animals is extremely important for the successful development of even some of the most basic behaviours. For example, if commercial chickens are raised without perches, they have to "learn" how to use perches in subsequent housing where perches are present (yes, I can provide the research articles). As for your comment "Behavior may or may not provide an evolutionary pressure." I do not see why you are limiting this to behaviour when the same is true of physiology - I suggest you read Vestigiality and then ask yourself why do our mammalian bodies use resources to produce nipples on the males when these have no function? Why do some species of cave fish develop eyes only to have these become covered in skin? Physiology is no better than behaviour at reacting to evolutionary pressures. But overall, it feels like you are moving the goalposts in this discussion and I have no idea why. DrChrissy ^(talk) 22:07, 12 February 2017 (UTC)

The question asks "Why do boys like girls long before spermarche? Why would evolution favor that?" The answer is that evolution does not favor that. That particular behavior has no known pressure on evolution. Liking girls in the absence of the ability to pass on genetic material fails to create a pressure on evolution. Bus stop (talk) 22:19, 12 February 2017 (UTC)

Thanks for completely ignoring my post. OK - let's get to the nitty gritty. Where is the evidence for what you are stating? Let's remember "Absence of evidence is not evidence of absence". DrChrissy ^(talk) 22:25, 12 February 2017 (UTC)

Evolution doesn't "favor" all things. Some observable phenomena are of secondary importance. Spermarche has to be "favored" by evolution due to its central role in reproduction. But "liking girls" (before spermarche) may not be the result of natural selection. It doesn't have such a central role in reproduction. (The question asked was "Why do boys like girls long before spermarche? Why would evolution favor that?") Bus stop (talk) 06:52, 13 February 2017 (UTC)

What do you mean by the term "secondary importance" in this context? Where is your evidence? " "liking girls" (before spermarche) may not be the result of natural selection."...if it is not due to natural selection, what process causes it and where is your evidence? DrChrissy ^(talk) 16:35, 13 February 2017 (UTC)

There are inconsequential traits. They don't drive evolution. We are discussing two traits. One is of central importance to the mechanism by which evolution functions. The other has no known bearing on the mechanism by which evolution functions. It is possible that sexual attraction prior to the ability to reproduce is of crucial importance in bringing about the changes that happen over generations, leading to important changes in the species. But there is no known mechanism by which that would occur. You and others have hypothesized about ways in which sexual attraction prior to the ability to reproduce can drive evolution. On the "plus side of the argument" it has been advanced that early sexual liaisons can prepare a boy for the later and all-important passing on of genetic material to the next generation. On the "minus side of the argument" it has been advanced that early sexual liaisons can lead to the transmission of sexually transmitted diseases which could perhaps diminish the ability to eventually pass genetic material to the next generation. But these are just hypotheses. And they contradict one another as concerns the net result. The question is "Why do boys like girls long before spermarche? Why would evolution favor that?" The answer is that there is no known evidence that evolution favors that. Boys may like girls prior to sexual maturity, but this may be irrelevant to evolution. You are asking me to provide evidence when it is your argument that requires evidence: what would make you think that boys liking girls prior to the ability to cause pregnancy is a trait that plays a part in natural selection? The question is actually a two part question. The relation between the two questions is problematic. One can ask the question "why do boys like girls long before spermarche?" but one can't logically follow it up by asking "why would evolution favor that?" because there is absolutely nothing supporting that evolution favors that. Bus stop (talk) 18:42, 13 February 2017 (UTC)

Ok. I am giving up here. You are repeatedly stating in a wiki-type voice assertions that are only your opinion - I say this because you have had ample time to produce evidence to support your assertions but you have not. I remind you this is a Science Reference Desk, it is not a Talk page. I have seen several conversations where editors are very concerned by the quality of information provided here, and I have seen one editor taken to AN/I for repeatedly and disruptively offering opinions rather than evidence. At the time, I thought this was rather harsh but having gone through the above interaction with you, I can see why the complaint was raised. You might like to reflect on this. DrChrissy ^(talk) 19:30, 13 February 2017 (UTC)

It is a good idea to respond responsibly to the question posed. In responding to the question you can't accept illogical assumptions built into the question posed. The question posed in this section has built into it an assumption that an observed behavior is a result of natural selection favoring that behavior. In fact there is no reason to assume that evolution, or natural selection, favors that behavioral trait. That, in a nutshell, is the most appropriate response to the question posed. The (paraphrased) question is asking why would evolution favor boys liking girls long before spermarche? There is no evidence that evolution favors boys liking girls long before spermarche. Bus stop (talk) 19:54, 13 February 2017 (UTC)

Consider the following: "Because living things have so many impressive adaptations (incredible camouflage, sneaky means of catching prey, flowers that attract just the right pollinators, etc.), it's easy to assume that all features of organisms must be adaptive in some way — to notice something about an organism and automatically wonder, "Now, what's that for?" While some traits are adaptive, it's important to keep in mind that many traits are not adaptations at all. Some may be the chance results of history."[4] Also see Not an adaptation. Bus stop (talk) 20:34, 13 February 2017 (UTC)

If boys liking girls before spermarche was just observed in one, two or few more ethnic and culturally separate peoples but not universally, BS may have a point. It is really down now to BS to undo the current anthropological view point that this is instinctive behaviour observable amongst all human societies. Even when they are isolated semi-savage tribes on French – Papua New Guinea.--Aspro (talk) 20:54, 13 February 2017 (UTC)

It is not up to Bus stop to do anything. Is there a source supportive of an argument that premature sexual activity helps the species to survive or reproduce? Evolution is not a default explanation for everything observable. There has to be information on this. The question posed at the top of this thread presupposes that evolution created the observed behavior. But that is a misassumption. Bus stop (talk) 21:04, 13 February 2017 (UTC)

Also see Misconception Monday: Everything is an Adaptation, Part 1 and Misconception Monday: Everything is an Adaptation, Part 2. Also see our article Spandrel (biology). Bus stop (talk) 03:15, 14 February 2017 (UTC)

I think science is prone to a weird sort of totemism, the overestimation of certain authors by people trying to look enlightened, and Gould is one of them. With "spandrels" I think he's trying to have his cake and eat it too -- on one hand, they are inseparable from arches (or supposed to be; see the criticism in that article), and on the other, they are supposed to not be adaptive while the arches are adaptive. I mean, what do you see with your eyes - the empty arch or the curved spandrel? Which holds up the roof? I imagine workers were paid to build both arch and spandrel together, never one or the other. And by the same token, it seems reasonable to suppose that any alleged genetic "spandrels" identified might show clear genetic signs of positive selection, not because they are adaptive mind you, but simply because ... well ... they're, ummm, necessary to make the adaptive mutations function properly. I don't care if every biologist on the planet quotes this as the height of wisdom, it still doesn't really make any sense to me. Wnt (talk) 18:12, 14 February 2017 (UTC)

I think the question which the reference desk is tasked with is providing responses supported by sources. The question posed presupposes that an observed phenomena can be explained in evolutionary terms. But that presupposition has no support that my admittedly feeble Google search can find. And no one else is presenting support in sources for the observed phenomena being underpinned by any evolutionary understanding. So the first order of business at the reference desk is questioning the assumption built into the question, namely that evolution favors the observed phenomena. In my opinion it is foolish to try to find an answer to a malformed question. I don't know if every observed trait has an evolutionary underpinning. What I did manage to find are the above links which posit that not every trait is adaptive, therefore a function of evolution. I oppose the answering of a question with mere guesses. Bus stop (talk) 18:54, 14 February 2017 (UTC)

The new born of higher primates take longer to develop and become independent. During that time they not only need feeding but protection from other members of the troop that would cause them harm and even kill them – and then want to mate with the female- so that his selfish gene gets passed on. Therefore, it is important for the female to bond with a strong male of the troop to ensure the survival of her offspring. Remember too, that in humans, gestation is nine months and that (biologically) is quite an investment for an female animal. The male instinct evolved to compliment. Modern day 'civilized' humans still exhibit this type of behaviour in war situations – we are still animals in that respect. This is nature both red in tooth and claw and we can't separate ourselfs from that. So this is the benefit of bonding before Spermarche. Hence, boys get interest in girls at an early age and girls get interest in boys... --Aspro (talk) 22:00, 11 February 2017 (UTC)

It's true that there's a whole lot of guesswork here, but maybe we can figure out some details? One thing I'm wondering: my recollection is before I was about nine, touching my penis when it was erect was unpleasant, in a way different from pain or other recognized sensations. (The sensation of erection itself was pleasant, provided it was left alone) At nine very limited external touching gradually began to seem favorable. Is there a technical term of some sort for that unpleasant sensation or its avoidance? I used to get the same kind of sensation if creating a vacuum in my navel with a fingertip, until about 30. Wnt (talk) 01:23, 15 February 2017 (UTC)

Likely the same reasons boys like boys before spermarche, girls like boys, and girls like girls before menarche. The evolutionary x stuff is just conjecture; we cannot falsify it but it is a lens through which to view the phenomenon. If you want something empirical, try looking at socialization, courting norms, etc. Or go the psychology route and look at the chemical rewards we get from love, attractions, and intimacy. (I assume we're talking about romantic attraction not than sexuality, but even the latter can be studied though those lines of inquiry). EvergreenFir (talk) 01:37, 15 February 2017 (UTC)

Humans being highly intelligent animals their behavior is mercurial and is unlikely to bear a fixed relationship to objective facts such as the time of maturity of sperm. Evolution can operate on behavior but more likely, in humans, behavior is somewhat independent of evolutionary adaptations of an objective nature such as the point in time of the maturation of sperm. This is just my opinion. Bus stop (talk) 02:02, 15 February 2017 (UTC)

Small female dogs getting knocked up by big male dogs

Sorry for the seemingly pornographic title, this is a serious and legitimate question.

If, for example, a male Great Dane (the biggest dog breed) managed to mate with and impregnate a female Chihuahua (dog) (the smallest dog breed - believe me, when there's a will, there's a way!), would there be a risk of the puppies being so big in utero (during the pregnancy), such that they would pose a risk to the Chihuahua mother? Or has nature already taken this into consideration, and the unborn puppies would still be small enough to make the pregnancy no more risky than any other?

I've encountered a dog whose dad was a Jack Russell and whose mom was a Border Collie (yes, they somehow managed to mate!), but never the sort of reverse situation (where the father dog was a far bigger breed than the mother). Anyone able to answer my question? I've long pondered this. Eliyohub (talk) 15:55, 11 February 2017 (UTC)

Not an answer to the question, but an analogy: a hinny has a horse father and a (generally smaller) donkey mother (the opposite of a mule). Our article says "Hinnies on average are slightly smaller than mules in part because donkeys are generally smaller than horses, and growth potential of equine offspring is influenced by the size of the dam's womb". This supports the notion that womb size can affect offspring size while allowing for viability. Whether this works in extreme cases like a giant male dog and a tiny female dog is another question. Is there a cutoff point for relative sizes for viability? Loraof (talk) 17:52, 11 February 2017 (UTC)

This question has come up several times previously on the ref desks, as here. I don't recall that a definitive answer has ever been given, though. Deor (talk) 18:25, 11 February 2017 (UTC)

My own experience (limited, but perhaps more than most as I worked as a vet nurse) of newborn pups is that their size is relatively constant. An adult great dane which might weigh 10 x (my figure) an adult chihuahua does not give birth to pups that are 10 x larger. This graph here[5] seems to support this. there is also this [6] Dog development compensates for this by larger dogs taking longer to develop and stop growing. DrChrissy ^(talk) 19:10, 11 February 2017 (UTC)

The question is intriguing; I'm not sure how to answer it but I went searching for in vitro fertilization in dogs, and found it only recently has been done. The Newsweek article says that the bitch was a hound, chosen because it is larger then the cocker spaniel x beagle or beagle x beagle pups. I see nothing in the article about whether the pups turned out larger because of the larger womb size, but potentially this would be a great way to look for influence because you might use highly inbred animals and look for non-genetic differences from in different bitches. Wnt (talk) 18:12, 12 February 2017 (UTC)

Humidity in heated room vs humidity in cold air

If someone is in a heated room and closed room, would he reduce or increase the humidity by aerating the room regularly? Would this change the thermal sensation?--Terurme (talk) 18:32, 11 February 2017 (UTC)

By "aerating" do you mean opening windows? ←Baseball Bugs ^{What's up, Doc?} carrots→ 19:12, 11 February 2017 (UTC)

Yes, maybe for a couple of minutes each hour.--Terurme (talk) 19:18, 11 February 2017 (UTC)

Assuming by "humidity" you mean relative humidity it will depend on the humidity outdoors, the humidity indoors, the temperature outdoors, and the temperature indoors. Shock Brigade Harvester Boris (talk) 19:24, 11 February 2017 (UTC)

We can assume that the temperature indoors is higher than outside, that's why the room is being heated. We can also assume that the humidity was the same at the beginning. --Terurme (talk) 19:39, 11 February 2017 (UTC)

If there are people in the room, or cooking going on then the absolute humidity in the closed room should increase. Swapping that air and reheating will decrease the humidity. Graeme Bartlett (talk) 20:22, 11 February 2017 (UTC)

Taking User:Terurme's conditions of identical starting relative humidity indoors and outdoors we can specify two possible outcomes:

• If the outdoor air is brought in and heated to the original indoor temperature, the temperature will be the same as the original indoor temperature (because we've made it so) and relative humidity will decrease.
• If the outdoor air is brought in and mixed with the indoor air without heating, the temperature will be somewhere between the original outdoor and indoor temperatures and the indoor relative humidity will increase.

Should there be sources or sinks of moisture within the room (as Graeme mentions) those will alter the indoor humidity correspondingly. Shock Brigade Harvester Boris (talk) 21:37, 11 February 2017 (UTC)

Note that some forms of heating directly increase humidity. In third world nations, an open fire in the center of a yurt or other structure, with a hole in the roof for ventilation, is often used. And see kerosene_heater#Moisture_Problems (propane heaters or heating a home with a gas stove/oven have a similar issue). Also, a "leaky" radiator system may release steam into the room. So, with such a system, opening a window to let out humidity would be counter-productive, as replacing the heat would also replace the humidity. StuRat (talk) 01:09, 12 February 2017 (UTC)

 

So wait, are you wanting to reduce the humidity, when it's cold? That strikes me as unusual. One of the problems with heating is very low relative humidity (because cold air with low absolute humidity, even if it's saturated with water vapor in absolute terms, is being warmed). Leads to dry skin and such. --Trovatore (talk) 05:19, 12 February 2017 (UTC)

One reason to reduce humidity indoors in winter is that it can otherwise condense on cold windows and exterior walls and cause mold to grow. Better insulation is another option, but not always possible to add to older homes. StuRat (talk) 05:24, 12 February 2017 (UTC)

Dampness in homes during winter is a common problem [7] [8] in a fair bit of New Zealand, partially because winters in some parts of NZ (Auckland for example) are quite wet. As this source [9] mentions, it should be managable but a combination of inadequate heating (most homes aren't centrally heated), inadequate ventilation and inadequate insulation means it persists. These can be related and can conflict. Inadequate insulation obviously means what heating there is is far less effective. On the flipside, as that source and this source [10] mentions, improved insulation can increase damp problems due to the reduce airflow/"breathing" of the house. Even worse if clothes are dried inside or a clothes dryer vented inside is used. (Other things like the lack of a range hood probably don't help either. This government advice [11] should give an idea of the various possible problem sources.)

If someone isn't able to improve things properly for whatever reason, using a dehumidifier to help reduce dampness isn't uncommon during winter for those who can afford it (various source mention this). (These also have the advantage of heating the room slightly, and with a generally higher COP than simple resistive heating.) As these sources mention [12] [13] [14] [15] it isn't just something Kiwis notice but many immigrants from temperate areas too.

In terms of the OPs question, with the NZ situation if you lack adequate ventilation simply opening your windows for a time during the day particularly when it's sunny, is a common recommendation [16] [17] [18] [19]. Also opening windows if you lack adequate extraction while cooking, showering etc [20] [21] [22]. There are obviously going to be situations where it makes it worse.

Nil Einne (talk) 14:36, 12 February 2017 (UTC)

Also note that in some places it may be possible to open windows to let the humidity out without letting the heat out. Say the temp drops to the 40's F at night, but rises to the 70's F during the day. You might have the heat on at night, but then be able to air the place out in the day. StuRat (talk) 15:01, 12 February 2017 (UTC)

Making breathable oxygen from water

So water is H2O which only has one oxygen atom in it, so it's O1. If you perform electrolysis on water, you'll get O1 and not O2. I was under the impression that O1 is toxic to breath in. Does O1 automatically form O2 after electrolysis? ScienceApe (talk) 19:49, 11 February 2017 (UTC)

Yes, it forms molecule automatically. Ruslik_Zero 19:53, 11 February 2017 (UTC)

 

See monatomic oxygen for a little more information. It's pretty sparse, though; someone should flesh it out. Basically it's a free radical and has a very strong tendency to combine, either with other oxygen atoms or with whatever's handy. Not much seems likely to make it to your lungs. I don't know how much ozone might come out of the reaction, though. That strikes me as potentially more of a problem. --Trovatore (talk) 19:56, 11 February 2017 (UTC)

Don't know if you have ever heard of a web site called Wikipedia but it has an article about almost everything. Electrolysis_of_water#Equations--Aspro (talk) 20:12, 11 February 2017 (UTC)

Wikipedia even has an page about wikipedia having an article about almost everything: WP:WHAAOE. DMacks (talk) 20:21, 11 February 2017 (UTC)

The chemical formula for the electrolysis of water reaction is 2H₂O + energy → 2H₂ + O₂. StuRat (talk) 20:37, 11 February 2017 (UTC)

@DMacks: Best to leave out the snark, because Wikipedia leaves a lot to be desired here. See [23]. According to that, the chemical mechanism is still a bit unsure. But it seems to be something where water becomes coordinated to a metal surface, such as Pt, then splits in a process (like oxidative addition?) where it has -OH tacked on to one atom and -H tacked onto the other. (is forming Pt-H "reductive addition"? H has electronegativity 2.20 and Pt 2.28, according to our article) Anyway, once some water is split, the H can join up with another and become H3O+, and the OH can become OH-, with an electron from the current source. Lone O attached to Pt or other metal would be relatively high energy if released, so unless there's a large overpotential I'm thinking it won't be, but will have to wander around on the surface until it finds a partner? Wnt (talk) 20:58, 11 February 2017 (UTC)

Aren't you talking about Aspro's snark, not mine? I didn't comment on the mechanism because I don't know what it is (not my area of chemistry) and conversely that I often hear it's still an active area of research. Google scholar has almost 1500 hits just for mechanism of electrolysis of water in 2017 already. DMacks (talk) 21:17, 11 February 2017 (UTC)

!Yes, you're right - I lost his signature in the links, sorry! Wnt (talk) 22:22, 11 February 2017 (UTC)

Think in that case, Wnt should up date the WP article as he pontificates to having a deeper understanding!--Aspro (talk) 22:19, 11 February 2017 (UTC)

Well, I can't include any question marks in the article... ought to do something, though, if someone else doesn't do it better first. Wnt (talk) 22:23, 11 February 2017 (UTC)

February 12

Thanks for your information on the loudness the flying insects but i have still a question that has been unanswered

I have seen a youtube video that is deletet now. there where people trying to catch a oliathus regius female that was taking of later high in the trees. Do you think they could actually hear it flying away? Saludacymbals (talk) 16:04, 12 February 2017 (UTC)

If you mean Goliathus regius which is a large beetle, it's possible. Here's a video about breeding them. Blooteuth (talk) 19:41, 12 February 2017 (UTC)

Antimatter

long confused/pseudoscientific rant by single purpose account, no req for refs
The following discussion has been closed. Please do not modify it.
wiki refers to matter and antimatter, and thus when the two are put together merged if you will, the result is essentially nothing, to me this is illogical because if matter is mass/energy and thus something how can less than nothing "antimatter" be possible? I can agree that particle may have negative charge via a pseudo zero quanta Eg such as it is with a centre tapped transformer feeding an asymmetrical power supply, having the centre tap as the pseudo zero and thus a relative positive and a relative negative voltage, "but note that zero is in fact a positive quanta" Thus much the same construct is possible with particles charges quanta, But how can "something" anything be merged with less than "nothing" to which results with nothing? can any one see how asinine that is? in short matter and less than zero matter or antimatter is simply asinine. Also when it comes to the Universe I want to know why it is not treated as a finite seeing it adheres to conservation? Eg: something can only begot from something else and nothing can never EVER contradict and be something, this means the universe is a finite quanta that has always existed, a finite because if we refer to everything then nothing is excluded and thus we indeed can rely on conservation to that finite quanta "100% or check sum to everything equating to 1 and thus all parts "constituents" are a percentage of it", meaning expansion, mind you a perceived accelerating expansion must be at the expense of some other unaccounted quanta, such as each and every Galaxy what with its core being a super black hole. Having said that though, I am quite sure, this accelerating expansion will be debunked, debunked once relativity data has been properly considered, data that has galaxies with an inward momentum, due to each and every stars storing energy via fusion, Eg: Merging two lighter atoms into a single heavier atom, thus increasing near vacuums "or an area with little mass that is mostly energetic" expansion, and thus taking up an atoms space for every fusion, to which as said near vacuum expands inwards towards new heavier atom said atoms gravity increases, to which if we apply that to the entire galaxy, what we indeed have is a perceived accelerating expansion specially if we rely on red shift changes..Korallrbare (talk) 21:16, 12 February 2017 (UTC) The reference desk is not the place to express one's misunderstanding or frustration with standard physics. This entire post should probably just be deleted; if you second that, feel free to do so. μηδείς (talk) 21:45, 12 February 2017 (UTC)

When matter and antimatter merge, the result isn't nothing, it's a great deal of energy, described by E = mc². See mass-energy equivalence. StuRat (talk) 21:59, 12 February 2017 (UTC)

I agree the OP is confused / confusing / over my head. But the modern theory of antimatter arose from the Dirac sea, the antielectron / positron thought of as a "hole in the sea of negative-energy electrons". Perhaps the OP had been reading about that.John Z (talk) 23:04, 12 February 2017 (UTC)

In addition to what StuRat mentioned, as our article says, antimatter is also mass/energy. The mass of corresponding antimatter is the same as the mass of matter. In that manner, it's misleading to call it less than nothing. If you call matter something, you could say I guess that it's an opposite form of something. Note the key word "form" here. I didn't say the opposite of something but the opposite form of something. Antimatter is still something, it's just a different, opposite type of something. (Incidentally any confusion here is why you should take care when trying to make English words correspond to concepts.) Consider what this means. As a being made of matter, I couldn't hold a ball of antimatter without what StuRat mentioned happening. But if I was a being of antimatter, a ball of antimatter would seem exactly the same as a corresponding ball of matter seems to me the being of matter. Of course if I were antimatter, unless I was magically converted from matter or something like that, I'd just call it matter and the other stuff would be antimatter. (Baryon asymmetry does complicate things but not at the level you seem to be thinking of, as far as we know.) BTW, I don't know if you're getting confused by negative mass, that is a different hypothetical concept. Nil Einne (talk) 03:10, 13 February 2017 (UTC)

It might be fun to go over Falaco solitons (we need an article): [24][25] for example. True, these physics particle analogies are rarely convincing, but at least the phenomenon is fun. Wnt (talk) 01:43, 15 February 2017 (UTC)

February 13

Lack of certain vitamines and\or minerals can make someone more appetative for eating ?

I know that people who lack Zinc tend to have less appetite. On the contrary, Did a vitamin or mineral that lacking it makes humans to be with more appetite ever found in the seemingly-objective scientific research? 77.180.51.125 (talk) 09:11, 13 February 2017 (UTC)

I wonder if there's anything in Pica that will help with this? --TammyMoet (talk) 14:45, 13 February 2017 (UTC)

See specific appetite. StuRat (talk) 14:50, 13 February 2017 (UTC)

What is the relationship between obesity and metabolic disorders?

1) Does being overweight cause metabolic diseases?

2) Does having a metabolic disease predispose the body to become overweight?

3) Or is there a confounding variable or are there many confounding variables?

4) Also, is it possible that a specific type of unbalanced diet cause obesity even if the number of calories is relatively low?

5) Socially, do malnourished, extremely thin people receive more sympathy than malnourished, overweight people? 107.77.194.85 (talk) 15:48, 13 February 2017 (UTC)

I numbered your Q's for those who wish to respond to specific ones.

• For 1 and 2, see metabolic syndrome.

• For 3, yes, it's quite confusing. For example, when trying to lose weight, you need to avoid triggering the starvation response. Genetics definitely play a role, too.

• For 4, not exactly. If you have a very low calorie diet, even if unhealthy, the average person should not become obese. However, it would be extremely difficult to keep your calories low on such a diet, as the lack of nutrients will make you constantly hungry. Also, eating extreme amounts of sodium may cause you to "gain weight" by retaining water and foods which cause constipation may cause weight gain from retained feces. Those aren't actually obesity but could be mistaken for it.

• For 5, sure, it's easier to see anorexia as a mental disease and being overweight as just a lack of control, probably because the average person gains weight when they stop worrying about what they eat, while losing weight seems like it requires an extreme effort. And for those people who are underweight because there is no food for them to eat, or they are physically sick, sympathy is even more common. An exception might be for fat toddlers, where clearly they are not to blame, it's either the parents or a medical problem. StuRat (talk) 15:53, 13 February 2017 (UTC)

Are the viruses infections is forever in the body after the enter?

I've seen the lecture (#1) of Prof. Vincent Racaniello from Columbia University on Youtube that says about the viruses infection "once infected it is for life" (see here 7:55). Does it says that a virus which already entered somebody, cannot be removable and it's there for all of the period of life? 93.126.88.30 (talk) 19:24, 13 February 2017 (UTC)

The major problem with the immune response to viruses is that they are internal parasites of cells. Antibodies and the cells that mediate the immune response have to react to either the cell surface, or to the debris of a cell destroyed by apoptosis or necrosis. If the virus is dormant inside a living cell, and not producing recognizable antigens, then it is camouflaged from the immune system, and hence "once infected it is for life". Retroviruses go even one step deeper. They not only infect the cell's cytoplasm, they get themselves inserted into the cell's own DNA, inside the nucleus, an even deeper level of attack.

Bacteria, on the other hand, often live outside the cell. They are easier to find (I am generalizing and simplifying) and they also have special metabolic needs and pathways for reproduction, and are hence susceptible to antibiotics, while viruses may or may not be susceptible to antivirals, and antivirals tend to be less selective, often being toxic to the patient as well. This is why the best attack against viruses is prevention through immunization when possible. After you have been infected, successful treatment is very difficult. See Hepatitis C for a type of virus which can be "cured" after infection.

See also Shingles, which result from an earlier chicken pox infection. The Zoster virus lies dormant in nerve cells until the patient loses effective immunity due to age or immunosuppression. The shingles vaccine works by getting the body primed to react to the virus if and when it resurfaces.

In any case, being "infected forever" does not always mean having active disease. μηδείς (talk) 20:36, 13 February 2017 (UTC)

It probably depends on which cells they infect, as some cells, like red blood cells, are replaced quite often, so a virus which solely infects them would need to be somewhat active to spread to other blood cells before the cells they are in are all destroyed and replaced. Nerve cells, on the other hand, may last your entire life, so a virus could remain dormant in those for decades. StuRat (talk) 21:13, 13 February 2017 (UTC)

To be clear, mature red blood cells do not have nuclei, and cannot be infected by viruses. Someguy1221 (talk) 21:17, 13 February 2017 (UTC)

It is only true of mammals that their red blood cells are anucleate. In other vertebrates they do have nuclei: see our article Nucleated red blood cell. Jmchutchinson (talk) 07:34, 14 February 2017 (UTC)

I viewed the relevant portion of the video, and I believe in context he's talking about the specific viruses he's named, which are listed on the same slide. These viruses are the herpesviruses, and it's true that those viruses produce latent infection. I don't believe all viruses do, though. Some, like influenza, just reproduce inside an infected cell and then destroy it to release the new viruses. See lytic cycle and lysogenic cycle. This is why you can develop shingles decades after infection with varicella, but you don't randomly re-develop the flu. --47.138.163.230 (talk) 06:57, 14 February 2017 (UTC)

What does the letter O in blood type O stands for?

93.126.88.30 (talk) 19:44, 13 February 2017 (UTC)

Type O blood: "Landsteiner originally described the O blood type as type "C", and in parts of Europe it is rendered as "0" (zero), signifying the lack of A or B antigen." So it seems it doesn't stand for anything directly, though it may be related to a zero, or a lack. SemanticMantis (talk) 19:55, 13 February 2017 (UTC)

Or Ordinary, being that it's the most common. Akld guy (talk) 20:08, 13 February 2017 (UTC)

Most common depends on where you look. E.g. O is not most common in Norway, see Blood_type_distribution_by_country. Also, do you have any sources for O standing for "ordinary"? I don't see that mentioned in our main article. SemanticMantis (talk) 20:17, 13 February 2017 (UTC)

Zero-sum discussion
The following discussion has been closed. Please do not modify it.
Throughout the world, type O is by far the most common. I didn't need to supply a source because you had already speculated that it might stand for zero or 'lack', so I was merely adding to the list of possible abbreviations. Akld guy (talk) 23:44, 13 February 2017 (UTC) Except that its standing for zero is not "speculation". ←Baseball Bugs What's up, Doc? carrots→ 01:15, 14 February 2017 (UTC) As for "oh" vs. "zero", "oh" is often used to mean "zero". If someone is batting .305, it will typically be read out loud as "three-oh-five", or a count of 0 balls and 2 strikes, for example, is typically said "oh and two". Even my modern telephone has "zero" standing for both the number zero and "Operator". ←Baseball Bugs What's up, Doc? carrots→ 01:19, 14 February 2017 (UTC) I bet you told your grandma how to suck eggs too. Akld guy (talk) 02:01, 14 February 2017 (UTC) I have no idea what that means. ←Baseball Bugs What's up, Doc? carrots→ 02:30, 14 February 2017 (UTC) Teaching grandmother to suck eggs. And you tout yourself as a person familiar with the English language?? Akld guy (talk) 04:06, 14 February 2017 (UTC) That's a hick expression I'd never heard until now. And I don't tout myself as an expert on anything. I'm merely a native speaker. ←Baseball Bugs What's up, Doc? carrots→ 11:12, 14 February 2017 (UTC) Don't dismiss it as a hick expression. It's still a very well known saying that happens to have almost fallen into disuse among the younger set. Akld guy (talk) 11:43, 14 February 2017 (UTC) Obviously Bugs has never read The Hobbit, whose author is reputed to have known something about the English language. {The poster formerly known as 87.81.230.195} 90.203.118.169 (talk) 15:59, 14 February 2017 (UTC) No, I've never read any of the Tolkien stuff. ←Baseball Bugs What's up, Doc? carrots→ 16:21, 14 February 2017 (UTC) The expression teaching grandmother to suck eggs is a stupid expression. Tolkien was a writer and this is a reference desk. We are not engaged in creative writing. Bus stop (talk) 16:13, 14 February 2017 (UTC)

EO concurs that the O was originally "zero".[26] ←Baseball Bugs ^{What's up, Doc?} carrots→ 21:50, 13 February 2017 (UTC)

You can find lots of references that say O, and lots that say 0. You can find refs that say "O" stands for "Ohne", and refs that say it never did. It's a complicated history; the original was "C", and all parties who were involved in the original dispute between "O" and "0" concur that it is proper to use the letter O for the blood group and not 0 or NULL. [27]. Not that that will lead the countries where the number 0 is used to change. - Nunh-huh 10:51, 15 February 2017 (UTC)

Proportional or Gravitational Constant “G”

Two masses are the requirement of newton's gravitational force in F= GMm/r^2 equation. Since gravitational constant “G” requires two masses in the equation of G = Fr^2/ Mm, therefore is it possible for “G = 6.67408 × 10-11 m3 kg-1 s-2” to exist if we have only a single mass in the whole universe?

No second or falling mass m means no force and hence no gravitational constant G but G appears in the equation of gravitational acceleration of gravitating mass M = GM/r^2 – is it possible?

Einstein says gravity is a not a force at all but the curvature of space-time, therefore according to dimensional analysis G seems to be depended upon density (unit of G = inverse unit of the density of time) – is this true if not why? 2001:56A:7399:1200:2998:3DF5:B730:21E8 (talk) 20:23, 13 February 2017 (UTC)EEK

It also depends on how you define a "thing". This is not trivial. Objects as large as galaxies exert gravitational attraction on each other (see, for example, galaxy cluster) and yet a galaxy is so diffuse you can go many light years between any substantially dense objects, from a human perspective. The only way to have a "one mass" universe is if your single particle is a fundamental particle, and even that may or may not be composed of simpler particles. There are serious theories in Physics which presume it's turtles all the way down, and there are no truly fundamental particles. So, your question of a "single mass universe" is not so simple as it just isn't that easy to draw a line between "one single mass" and "a bunch of individual masses close together". --Jayron32 20:40, 13 February 2017 (UTC)

I would also note that G the gravitational constant exists whether or not anything exists for which it matters, although at that point it's meaningless. Pi exists even if no one uses math. Someguy1221 (talk) 22:04, 13 February 2017 (UTC)

That's an interesting philosophical Q. After all, we could come up with an infinite number of laws describing how various forms of nonexistent exotic matter behave, couldn't we ? StuRat (talk) 22:15, 13 February 2017 (UTC)

Philosophy aside, it is impossible for a non-pointlike universe to contain only a single mass. If our present-day understanding of physics is correct, there is a nonzero energy (and therefore mass) associated with null-oscillations of various fields; and therefore any volume of what we think of as a "vacuum" still has some mass. It is not presently known, however, what this mass is. Please see Zero-point_energy and Cosmological constant problem, respectively. Dr Dima (talk) 01:18, 14 February 2017 (UTC)

Hooke and the monk's room

I was clicking around and noticed something curious: some of our articles about cells claim that Hooke chose the name because he thought that what he was observing looked like monks' cells (generally sourced by throwaway lines from bio textbooks), and some of them claim that he chose the name because he thought they resembled the cells in a honeycomb. A quick look at an online copy of Micrographia shows that, first, he never says anything about monks in it, and second, he does talk about the sexangular cells of the honeycomb before going on to say "these pores, or cells...". Has anyone ever investigated the origin of the monk story? Is there some letter somewhere where he says "hey these things are a lot like a monk's room", or was it made up from whole cloth in the year X by author Y? -165.234.252.11 (talk) 20:52, 13 February 2017 (UTC)

Robert Hooke first observed cells in 1665 on a thin slice of cork under a simple microscope. The Online Etymology Dictionary notes[28] only that cell was used in 14c., figuratively, of brain "compartments;" used in biology by 17c. of various cavities (wood structure, segments of fruit, bee combs), gradually focusing to the modern sense of "basic structure of living organisms" (which OED dates to 1845). The source for Hooke's thinking of monks' cells is Achiever's Biology (1990) by Alan Chong Tero. Blooteuth (talk) 00:17, 14 February 2017 (UTC)

The OED has a cites from hundreds of years earlier (1395): "Such wonyng places [sc. of bees] and celles ben alle sexe cornered"; then from 1425: "Also, swete Ihesu, þi bodi is lyke to an hony combe, ffor it is eche way fulle of cellis, and eche celle fulle of hony", and a couple more for honeycomb cells before Hooke's usage. Hooke was probably the first to use it of cork, but the OED comments: "Although Robert Hooke, Nehemiah Grew and other writers used the word for microscopic cavities found in plant tissues, the modern understanding of the cell is usually taken to begin in the early 19th cent. with the work of J. B. Purkinje and other (mainly French and German) botanists and anatomists, and is particularly associated with M. J. Schleiden (in plants) ( Arch. f. Anat., Physiol. u. wissensch. Med. (1838) 137) and T. Schwann (in animals) ( Mikroskop. Untersuchungen (1839))." Dbfirs 16:44, 14 February 2017 (UTC)

I found the original here. [29] Yes, it's just somebody long before the invention of the microscope saying that Jesus' body is made up of cells. Mystics... always just enough inexplicable insight to make you wonder, never enough to prove anything to a skeptic. ;) Wnt (talk) 00:49, 15 February 2017 (UTC)

February 14

How could the universe be infinite?

Apparently the universe could be finite or infinite. I'm curious how it could be infinite given the universe has an age and finite speed of expansion? — Preceding unsigned comment added by 2.102.184.32 (talk) 03:23, 14 February 2017 (UTC)

Simple. It was always infinite <added>at any positive time after the Big Bang</added>. In an infinite universe, the Big Bang was not a moment of zero size, but rather <added>and also</added> of infinite (or maximum) density. We have some discussion of this at size of the universe and shape of the universe. Someguy1221 (talk) 03:29, 14 February 2017 (UTC)

So the Universe at the time of the Big Bang was just a tiny area, but in that tiny area there was an infinite density of stuff, and when it exploded the infinite stuff expanded to an infinite area?— Preceding unsigned comment added by 2.102.184.32 (talk • contribs)

<added>Yes</added>Not quite. The theory would go that at the time of the Big Bang, the universe was infinite in both density and extent. It never went from finite to infinite. You might ask how something infinite can get bigger... well, it can. In the case of the universe, an expanding and infinite universe is merely one in which though the total size is always "infinity", the bits inside are getting further apart from one another at all times. Someguy1221 (talk) 04:42, 14 February 2017 (UTC)

It's not clear that it's meaningful to talk about the exact moment of the Big Bang. Cosmologists can tell all sorts of things about what happened 100,000 years after the Big Bang, or 1 second after it, or 10⁻³⁵ seconds after it, but you'll basically never see them say anything about exactly 0 seconds.

That said, it's possible to make sense, at least mathematically, of the universe having infinite extent at any positive time after the Big Bang, but zero extent at the exact moment of the Big Bang. I'll elaborate below. --Trovatore (talk) 04:46, 14 February 2017 (UTC)

You know what, Trovatore, I think you have to be right, and I have to be wrong. Thanks for throwing me the "any positive time after the big bang" life raft :) Someguy1221 (talk) 05:03, 14 February 2017 (UTC)

(edit conflict)Just a bit more on how something infinite can get bigger, a lot of people have trouble thinking about infinity as mathematicians do. Take an example. There are infinity numbers between 0 and 1, because you can write nonrepeating decimal expansions forever. There are also infinity numbers between 0 and 10. Are there more numbers between 0 and 10, than between 0 and 1? All numbers between 0 and 1, are also between 0 and 10. But the interval from 0 to 10 also has numbers that aren't between 0 and 1. So you'd like to say that there are more numbers in the larger span. But it's definitely true that both spans contain infinity numbers. If you accept that this is logical, then you may also accept that a universe that was always infinite in size can get bigger, defined as the average space between particles at least. Someguy1221 (talk) 04:48, 14 February 2017 (UTC)

(edit conflict) Wikipedia has an article titled shape of the universe which discusses some of the geometric possibilities that could produce an infinite universe. You aren't the first person to wrestle with such issues; see Olbers' paradox for one such famous issue with infinity. --Jayron32 03:31, 14 February 2017 (UTC)

Actually its all still unknown. The Big Bang is an widely agreed assumption, not a proven fact! The universe may be much older or maybe it was always here. Neither the "age of the universe" nor "its rate of expansion" are really "given" facts in scientific sense, so your basic assumption is already wrong. Both are infact also "just" widely agreed on assumptions aswell. Astrophysics still has allot of homework to do on what has been discovered by astronomy and astronomy is barley started. Remember Hubble Space Telescope is just 26 years young and it is a very restricted instrument, atleast compared to the new James Webb Space Telescope, that will start collecting new facts in 2 years.

Likely there are some groundbraking discoveries about to be made in the near future and it will not be the first time big theories get dumped into history books as nice try but proven to be wrong if they find stuff that doesnt add up. --Kharon (talk) 04:25, 14 February 2017 (UTC)

Saying the Big Bang is "not a proven fact" is disingenuous. It is enormously well-supported by evidence. Scientific theories, especially well-tested theories like the Big Bang, aren't just guesses. (I'm reminded of the frequent creationist canard that "evolution is only a theory!") It's true that theories are adjusted to account for new evidence, but that doesn't mean learning anything new requires us to throw them out and start over from scratch. As Lawrence Krauss is quoted as stating in our Big Bang article, "[The] big bang picture is too firmly grounded in data from every area to be proved invalid in its general features." --47.138.163.230 (talk) 06:45, 14 February 2017 (UTC)

To concur with 47.138, it should be noted that you are not a proven fact. However, the Big Bang is as well accepted as anything else, so there's no need to say that it "isn't a proven fact". If you demanded more proof for the Big Bang than currently exists, then you probably don't believe anything has ever been proven ever. --Jayron32 12:01, 14 February 2017 (UTC)

But the February 2017 Scientific American has an article by 3 astrophysicists, 2 from Princeton and 1 from Harvard, saying that in their opinion the latest data strongly refutes the Big Bang, and they favor a Big Bounce from a previously contracting universe as an alternative theory consistent with the data. Loraof (talk) 17:36, 14 February 2017 (UTC)

We have an article on the Big Bounce theory. It's actually conceptually very similar to the Big Bang, in that ~13.7 billion years ago the universe was contracted into an immensely dense, tiny volume. They differ fundamentally in that Big Bounce posits a "before". Big Bounce could be true, possibly while keeping true most of the Big Bang theory. Someguy1221 (talk) 01:16, 15 February 2017 (UTC)

Per Someguy1221, the story is clearly "Some scientists have proposed refining current theories about the origin of the universe" and not "SCIENTISTS NOW SAY EVERYTHING YOU KNOW IS WRONG!" Science works this way by small incremental changes to established theories. Complete rejection of established, well-supported theories are exceedingly rare, instead most of the major work is in refinement. The popular press (and/or the Intelligent Design crowd) latch on to these refinements and blow them way out of proportion to say "SCIENCE SAYS X IS WRONG" or "SCIENTISTS DON'T KNOW WHAT THEY ARE DOING" when, in reality, these sorts of tweaks and changes to theories happen continuously, and don't prove that older scientific theories were wrong, just that we get better results with more accumulated knowledge. --Jayron32 13:16, 15 February 2017 (UTC)

Here's a silly toy example that is absolutely not a picture of the actual universe, but might give some insight into how such a thing could be logically possible.

Suppose the universe is laid out on a standard 3-dimensional Cartesian coordinate system, where at any fixed comoving time, every point has a set of coordinates (x, y, z) for some real numbers x, y, z.

Now suppose that all particles go exactly with the Hubble flow, and that each particle has three coordinates x₀, y₀, z₀ that tell you where it is at one second after the Big Bang.

Suppose further that, at any time t seconds after the Big Bang, said particle is at position (tx₀, ty₀, tz₀).

Then you can easily check that, at any positive time t, there are particles arbitrarily far apart from one another.

However, at the exact moment of the Big Bang, namely t=0, all particles are at location (0, 0, 0). --Trovatore (talk) 04:54, 14 February 2017 (UTC)

I found your toy example extremely useful. I got it wrong above at first, but I found your argument excellent when thinking of the problem backwards. Instead of asking what happens after the Big Bang, asking what happens starting from the present and working back. Now of course if the universe is finite in size, you can compress it as much as you want, and it won't reach infinite density as long as its volume is non zero. Well, if you start with an infinite universe, it's actually still really hard to get infinite density. As long as there is space between particles (assumed to be points), you can keep compressing forever. You can get any two particles, arbitrarily far apart in the universe, to be arbitrarily close, without ever hitting infinite density. In this thought experiment, you don't reach infinite density unless every particle is touching every other particle. Now this started with an infinite extent, infinite mass, finite density universe. If we work forward from my initial (and now I think wrong) assumption of a universe with infinite extent, mass and density, I'm not sure you ever get a universe that is not all of the above. I won't drone on about a counterfactual, but I don't think logic (let alone physics) even works. So thanks again. Someguy1221 (talk) 05:18, 14 February 2017 (UTC)

Suggested videos from PBS Space Time: [30] [31] [32] --47.138.163.230 (talk) 06:45, 14 February 2017 (UTC)

I suspect the toy example leads astray. The molecules are not expanding neatly at kx, ky, kz. They are moving all over the place, smashing against each other. A second after the Big Bang every molecule was colliding with some unimaginable number of other molecules, so in that "short" amount of time, a whole lot of stuff was going on. I don't know if simply taking ln t = "tau" is really an accurate way to look at it, but I think we can put an infinite amount of history into a finite amount of time - under regimes of physics that used ever smaller Compton radii for ever larger masses for particles stable on ever smaller time scales the further back you look. Eventually they get down the Planck radius, particles that are black holes, nobody knows what happens - but this is not a guarantee that physics before that point was boring or nonexistent ... it gives quite a hint to the contrary. Wnt (talk) 17:52, 14 February 2017 (UTC)

Well, it was an example with a very limited purpose, to show that it's logically possible to have a universe with finite (actually zero) extent at one instant, and infinite extent at all later moments. You can't ask too much of it.

I do have a sort of a similar picture to yours; a universe that actually has no first instant, but just has a time coordinate that converges when you look backwards in time. As to whether there's anything interesting to say about the pre-Planck-time epoch, who knows. --Trovatore (talk) 19:39, 14 February 2017 (UTC)

Feynman Lectures. Lecture 48. Ch.48-3 [33]

...

The television problem is more difficult. As the electron beam goes across the face of the picture tube, there are various little spots of light and dark. That “light” and “dark” is the “signal.” Now ordinarily the beam scans over the whole picture, 500 lines, approximately, in a thirtieth of a second. Let us consider that the resolution of the picture vertically and horizontally is more or less the same, so that there are the same number of spots per inch along a scan line. We want to be able to distinguish dark from light, dark from light, dark from light, over, say, 500 lines. In order to be able to do this with cosine waves, the shortest wavelength needed thus corresponds to a wavelength, from maximum to maximum, of one 250th of the screen size. So we have 250×500×30 pieces of information per second. The highest frequency that we are going to carry, therefore, is close to 4 megacycles per second. Actually, to keep the television stations apart, we have to use a little bit more than this, about 6 mc/sec; part of it is used to carry the sound signal, and other information. So, television channels are 6 megacycles per second wide. It certainly would not be possible to transmit tv on an 800 kc/sec carrier, since we cannot modulate at a higher frequency than the carrier.

— Feynman • Leighton • Sands, The Feynman Lectures on Physics, Volume I

How did he derived the number 250 and why must it be the wavelength? So I assume that the maximum of modulating signal amplitude is converted to the increasing electron emission from CRT and so white spot; the minimum of amplitude is the decreasing emission and dark spot. These spots are within the same line (one of 500), are adjacent , situated horizontally (as lines are horizontal) and have a diameter = 1 line width. Is it correct? Can the equipment modulate the carrier wave like this png so on the screen we see only one spot? Username160611000000 (talk) 05:23, 14 February 2017 (UTC)

A white spot adjacent to a black spot represents one cycle of the highest video frequency required, which is half the number of spots scanned per second. Assuming that the transition from spot to spot is a sine (or cosine) wave means that no higher frequency is needed (whereas abrupt black/white changes as in a chequerboard image would involve squarewaves and much higher harmonic frequencies). He calculates "4 megacycles per second" which is better expressed as 4 MHz. The 4 MHz video signal can be modulated on any higher frequency carrier for broadcasting. Simple Amplitude modulation would transmit sideband frequencies (F_c - 4) and (F_c + 4) MHz however this wastes precious bandwidth so the lower sideband is mostly suppressed and receivers are designed to demodulate the resulting vestigial sideband signal. The explanation serves as an introduction to the NTSC#Transmission modulation scheme that occupies a total bandwidth of 6 MHz. Blooteuth (talk) 19:14, 14 February 2017 (UTC)

Nuclear fallout

If terrorists detonate an atom bomb in the area of Wichita, KS, what amount of food and non-food crops would be contaminated by the fallout? Would that result in actual food shortages in the USA (to the point where some people would have to go without certain foods or where rationing would have to be put in place), or would it only cause increases in the price of food? If the latter, approximately how much of an impact would it have? In either case, for how long would the land remain contaminated and unusable for growing crops (i.e. how long would it be before agriculture in the area could return to normal again)? (Assume that the explosive yield of the bomb is 45 kt (the biggest nuke which those vermin could realistically obtain at present), that the detonation is at ground level (worst-case scenario in terms of radiation), and that prevailing winds prevail.) 2601:646:8E01:7E0B:9076:92A3:E19C:2F76 (talk) 06:38, 14 February 2017 (UTC)

"We don't answer requests for opinions, predictions or debate." See the page header. --47.138.163.230 (talk) 07:00, 14 February 2017 (UTC)

Would you have answered the question if I specified the location as Broken Arrow, OK? 2601:646:8E01:7E0B:9076:92A3:E19C:2F76 (talk) 10:28, 14 February 2017 (UTC)

There is a gem of an answerable question in there. Someone should be able to find references on how much agricultural land around a nuclear blast is expected to become unusable in the short term. This was once a very hot topic of research. Someguy1221 (talk) 08:21, 14 February 2017 (UTC)

Well, I've actually done the first part of the research -- I've played out this scenario on Nukemap, and it shows that with 15 knots of wind from the southwest (which may or may not actually be the prevailing wind, I don't know), the fallout plume would stretch almost as far as Topeka: http://www.nuclearsecrecy.com/nukemap/ So, with the fallout plume as shown, how much farmland would be contaminated, and how long would it stay that way -- and how much would it hurt food production? 2601:646:8E01:7E0B:9076:92A3:E19C:2F76 (talk) 10:41, 14 February 2017 (UTC)

We can generate a pretty good answer from history, and that answer is "nationwide food production and price changes would be negligible". The US has detonated over 600 kilotons of surface-level nuclear weapons within the continental US, with over 500 kilotons additionally detonated over the US at airburst levels. This is of much higher magnitude than the suggested range for a single terrorist bomb, and no widespread fallout (to the degree that it materially impacted the availability of food) was observed. Any single low-yield nuclear detonation can be safely characterized as being local in scope (however horrific that local scope may be), and the food production of the US is not constrained to any particular local scope. At most, you might find some highly-localized specialty crop that could be substantially disrupted, but not staples. — Lomn 15:42, 14 February 2017 (UTC)

Editing to add: Here's a map of fallout from the Nevada Test Site. It's clearly quite extensive over the Great Plains, so it's not as if major farming regions didn't experience the effects of several hundred kilotons of nuclear detonations. — Lomn 15:48, 14 February 2017 (UTC)

Thanks! So I understand the answer is, not much of an impact on food supplies, right? 2601:646:8E01:7E0B:64B4:64AD:FCBF:2883 (talk) 09:04, 15 February 2017 (UTC)

Here's a 70-page book, available at no cost, from the RAND Corporation: Technical Report 391, Considering the Effects of a Catastrophic Terrorist Attack (2006). If you're the sort who likes to read about these things, it's good to learn a few good sources: RAND publishes a huge library of very professional-quality research on science and policy topics like this one, and the overwhelming majority of their library is available at no cost (!) because some famous historical guy figured that the cost-benefit of an informed public, educated by free, free information, outweighed the risk of controversial information "leaking out."

On the topic of vermin, a senior member of the White House staff was recently ousted for being overly-friendly with our nation's arch-nuclear-rival.... It was his published opinion that Islamic terrorist group Al Qaeda remains as-strong-as-ever. I wonder if we can believe him!

One of my professors and a fellow pilot, Martin Hellman, worked with a few senators and politicians and researchers to found Nuclear Risk, a very alarmist organization whose primary objective, apparently, is turning intellectuals into insomniacs. They publish a lot of information on realities and speculations of 21st-century nuclear war. I find that experienced glider pilots tend to see things that we often cannot see from ground-level.

And lastly, if you haven't yet read The Bulletin, have a glance at their motives for moving their metaphorical "doomsday clock" to its most desperate setting since the invention of the hydrogen bomb in 1953. "...intemperate statements, lack of openness to expert advice, and questionable cabinet nominations have already made a bad international security situation worse."

To quote disenfranchised Arab musician Ghassan Rahbani, we're all chickens and there are foxes guarding the hen house.

Nimur (talk) 15:46, 14 February 2017 (UTC)

First of all, even if Flynn was in cahoots with the Russians (which is probably just lies created by rogue elements in our intelligence services in any case), it DOES NOT invalidate his assessment of Al-Qaida -- read Ad hominem fallacy, for God's sake! Second of all, President Trump's cabinet nominations, with a couple of exceptions, have been THE BEST in recent history -- in fact, they are THE FIRST cabinet nominees IN HISTORY to take the threat of Islam seriously! And why would ANYONE believe some raghead musician (i.e. a self-evident NON-expert, and moreover one with a VESTED INTEREST in HARMING our nation) over MULTIPLE EXPERTS in matters of NATIONAL SECURITY?! 2601:646:8E01:7E0B:64B4:64AD:FCBF:2883 (talk) 09:12, 15 February 2017 (UTC)

I'm not familiar with Ghassan Rahbani or his music. Can you explain in what way he has a vested interest in harming the US? (Preferably without resorting to racial slurs or excessive use of capitalization). Iapetus (talk) 10:26, 15 February 2017 (UTC)

Incidentally, the slur seems even sillier here than normal since AFAICT, Ghassan Rahbani does not generally wear a turban or keffiyeh. Nil Einne (talk) 14:39, 15 February 2017 (UTC)

My OpInIoN iS MoRe iMPoRtanT anD cORReCt beCAUse I usE randOm caPiTal letters? --Stephan Schulz (talk) 10:23, 15 February 2017 (UTC)

The Lebanese do not wear rags on their heads. That's a pretty impolite thing to insinuate; and in my neighborhood, it's a poor life-choice to become impolite with a Lebanese individual. Regarding headwear: there is a long and complex tradition of Taqiya Taqiya that is rooted in some important political history, and some of the young people are bringing it back to make an ironic statement. It might serve you well to expand your cultural horizons: here's the music in question - a hip-hop song about the difficulties of pacifism - but you kind of have to come from a rough neighborhood to appreciate that kind of music. Nimur (talk) 14:45, 15 February 2017 (UTC)

Note the answer would deeply involve human psychology. That is, how many people would be unwilling to feed their family food that is "only slightly contaminated but deemed to be safe by the government". Considering the level of distrust of government in the US, I suspect many people wouldn't believe the US government. And, if food wasn't labelled as coming from the contaminated area, that might cause people to avoid all food that might possibly be from there, instead preferring foods that were canned before the event or that don't grow in that region.

The public reaction to the food supply following the Fukushima Daiichi nuclear disaster may also be relevant. StuRat (talk) 17:30, 14 February 2017 (UTC)

The form of resulting ground contamination would be very dependent on weather conditions. Dry weather with strong winds could spread the contamination in a stripe over a hole continent. Enough rain would keep it a very local ground contamination. If the catastrophy would happen right at or near the shore of an Ocean, like in Fukushima, and the wind direction would transport most of the fallout away from the landmass, it would be minimal. --Kharon (talk) 14:46, 15 February 2017 (UTC)

What to call '2A "self-cleavage" peptide?

There's this short peptide sequence that when it's translated from mRNA results in a break in the nascent peptide and it's called '2A'. It was or is commonly called a "self-cleavage" peptide because, I think, that was how it was once supposed to function but that is now known not to be the case. If it's not a "self-cleavage" peptide, what kind of peptide can it be called? --129.215.47.59 (talk) 14:19, 14 February 2017 (UTC)

The preferred terminology appears to be self-cleaving peptide. --Jayron32 15:06, 14 February 2017 (UTC)

But it's not self-cleaving. --129.215.47.59 (talk) 16:13, 14 February 2017 (UTC)

But that's what it's called in the literature, so that's "what it's called" or at least a common and recognizeable term among those in the field. And what wikipedia would call an article, for the same reason. It's known that it's a misnomer (see for example doi:10.1186/s13068-017-0710-7 and references therein), but also hardly the first time a now-disproven idea has persisted in nomenclature. DMacks (talk) 16:33, 14 February 2017 (UTC)

This calls it the 2A self-processing peptide, FWIW. While this paper just calls it "2A peptide" in many places, and says (citing this, which looks likely to be the original skip paper): "2A and 2A-like sequences are now referred to as CHYSELs (cis-acting hydrolase elements) rather than self-cleaving peptides". As an article title I'd prefer the phrase in words - the acronym seems too clever by half. Wnt (talk) 17:28, 14 February 2017 (UTC)

What is subcloning? I think article might be wrong

According to the article subcloning is "a technique used to move a particular gene of interest from a parent vector to a destination vector in order to further study its functionality". What if you don't want to study its functionality? What if you just want the expression cassette out of one reporter to put in another? Is that not subcloning? --129.215.47.59 (talk) 15:04, 14 February 2017 (UTC)

I believe that's just cloning. --Jayron32 15:07, 14 February 2017 (UTC)

• The definition is wrong (well not wrong, just too specific). Moving any genetic material from one vector to another is generally referred to as subcloning. Amplifying the genetic material from its native environment (DNA, mRNA etc) into vector-based cDNA is molecular cloning. Fgf10 (talk) 15:37, 14 February 2017 (UTC)

I agree the "in order" should be a different sentence; "this might be done in order...". Cloning is to subcloning as letting (renting out) an apartment is to subletting it. So long as you are growing up many identical copies of the genetic sequence, and you started with something you'd already cloned, it's subcloning. (But subcloning is still a kind of cloning, just as subletting is a kind of letting, as after all (as the Jurassic Park novel famously pointed out) many "cloning" experimental sequences have turned out to have started inadvertently with plasmid DNA!) Wnt (talk) 17:43, 14 February 2017 (UTC)

How long does a fecal transplant last?

I was in a seminar recently and it was discussed that after an effort is made to change a person's microbial flora it reverts back to the original state and is based on their genetics. I've heard of fecal transplants as treatments for people with some gastrointestinal diseases and I've heard of these causing obesity when fecal material was sourced from an obese donor. Does the microflora return to the disease state and/or patient to original body weight? --129.215.47.59 (talk) 16:26, 14 February 2017 (UTC)

Wikipedia has an article titled Fecal microbiota transplant which covers the procedure. According to the Wikipedia article, obesity is only mentioned in passing as a "potential" application. It does not mention the mechanism by which it may work to treat obesity. --Jayron32 16:56, 14 February 2017 (UTC)

The Q was about it causing obesity, not treating it. StuRat (talk) 17:34, 14 February 2017 (UTC)

Note that the gut microbiome also greatly depends on what the person eats, and specifically probiotics and prebiotics. A transplant won't last long if the intestinal environment does not allow for the survival of those organisms, or could last a lifetime, if it does. StuRat (talk) 17:38, 14 February 2017 (UTC)

Is that a guess, or could you give us a reference for both parts of your last sentence? Loraof (talk) 02:10, 15 February 2017 (UTC)

You want a source for the statement that organisms won't survive in an environment that doesn't allow for their survival, and could survive in an environment that does allow for their survival ? StuRat (talk) 03:30, 15 February 2017 (UTC)

personal dispute
The following discussion has been closed. Please do not modify it.
A source for anything you say ever would be a nice start. --Jayron32 04:00, 15 February 2017 (UTC) Let's see a source for your claim that I've never provided a source for anything I've ever said. I've provided many sources to debunk that lie, now it's your turn to defend it. StuRat (talk) 04:28, 15 February 2017 (UTC)

An example of the claim that what you consume affects your gut flora... Many (too many to list) studies have concluded that consumption of artificial sweeteners negatively impacts gut bacteria and most of these studies correlate the altered gut bacteria with a predisposition to weight gain. [34] [35] [36] [37] (is that enough references to support the claim?) 209.149.113.5 (talk) 14:56, 15 February 2017 (UTC)

Nanobots slowing aging

Will nanobots be eventually able to actually reverse aging, or will they just slow it down?Uncle dan is home (talk) 18:11, 14 February 2017 (UTC)

The article Ageing explains what we theorize about it, that it is a combination of accumulated damage (such as DNA oxidation) and programmed processes (such as DNA oxidation). Nanorobotics is an emerging technology that has potential medical applications such as directed drug delivery e.g. to cancer cells, and even assisting White blood cells protect the body. However the Ref. Desk will not give the OP a prediction about achieving Immortality (see article). Blooteuth (talk) 18:35, 14 February 2017 (UTC)

There is potential to repair DNA, such as lengthening telomeres on chromosomes and fixing errors within the DNA. Not sure if nanobots or programmed viruses would be the method. Note that fixing errors requires a "correct" version of the DNA to compare with, so cells from that individual, frozen at birth, might be useful there. Otherwise you would need to compare many damaged DNA samples to try to determine what the original undamaged version was. StuRat (talk) 18:40, 14 February 2017 (UTC)

Blood type distribution by country

Our article at Blood type distribution by country has been tagged "factual accuracy is disputed" since 2012. Does anyone have a source that can be used to either correct the article or remove the tag? --Guy Macon (talk) 18:26, 14 February 2017 (UTC)

Some possible leads to follow: [38], [39], [40], [41]. All of these were found on the first page of a Google search with the phrase blood type distribution. If you try that yourself, you may find more references you can use. --Jayron32 18:51, 14 February 2017 (UTC)

Does porn change the sexual preferences?

Does porn change the sexual preferences? If people are given access to different types of porn, which they find appealing, would that result in a different sexual preferences? Would they ignore the types they don't have access to?--Llaanngg (talk) 19:39, 14 February 2017 (UTC)

Some good faith answers on sexual orientation, but OP was interested in sex acts. Also some meta-discussion on conduct. Collapsed for clarity.

Wikipedia has an extensive article titled Sexual orientation which discusses a myriad of factors that may or may not affect a person's sexual preferences. It does not mention any effect of pornography generally, but does contain several statements from respected organizations and researchers to the effect of " mechanisms for the development of a particular sexual orientation remain unclear" and " there is no scientific consensus about the specific factors that cause an individual to become heterosexual, homosexual, or bisexual" and "No one knows what causes heterosexuality, homosexuality, or bisexuality." and " [there is no] conclusion based in sound science at the present time as to the cause or causes of sexual orientation". So, take that as you may. --Jayron32 19:49, 14 February 2017 (UTC) Note that the age at which the exposure occurs may well be critical, as sexual orientation tends to be more flexible at an earlier age. Also note that if someone was exposed to homosexual porn at an early age, and became a homosexual adult, there are at least 3 possible conclusions: They were heterosexual, and the gay porn "turned them gay". They were genetically predisposed to be homosexual, but would have repressed this tendency if they had no "gay role models". They would have become a homosexual adult in any case. So, the exact nature of the cause and effect, if indeed there is any, is open for debate. StuRat (talk) 20:53, 14 February 2017 (UTC) Do you ever read anything about actual research in this area, by actual experts who study it, or do you just make shit up as you go along as usual. "gay porn turned them gay"? Do you have any idea how absolutely backwards and bigoted that sounds given what we know about this? This is why we don't tell people what "we know" here at the reference desk. Give them reading material and let them figure it out. Jeez Stu, you've reached a new low here today. --Jayron32 03:59, 15 February 2017 (UTC) Do YOU have any idea how absolutely STUPID you sound accusing StuRat of being "bigoted" just for bringing up a possibility of gay porn turning someone gay? BTW, there HAVE been in fact cases of straight people becoming gay and vice versa, so this possibility is not even that far out! 2601:646:8E01:7E0B:64B4:64AD:FCBF:2883 (talk) 09:18, 15 February 2017 (UTC) there HAVE been in fact cases of straight people becoming gay and vice versa - It sounds plausible enough to me, but that doesn't mean it's true. TigraanClick here to contact me 13:56, 15 February 2017 (UTC) Well, sure, there is fluidity of sexual orientation, but recognizing that is different then the sort of "we can just make him straight" or "X made him gay" sort of thinking. A person's sexuality can be fluid, and can change throughout someone's life, but the idea that sexuality can be reliably controlled by outside factors is what leads to bullshit like conversion therapy. Yes, sexuality can change. No, you cannot make it change. --Jayron32 14:48, 15 February 2017 (UTC) I'm pretty sure he was just talking about how, logically, a correlation can have multiple possible explanations, and showing that there are alternatives to the theory that watching it changed them. Its analogous to saying: "If someone claims they were abducted by aliens, there are at least 3 possible conclusions: 1) They were abducted by aliens; 2) They're just making it up; 3) They imagined it". Listing an implausible explanation alongside more reasonable ones doesn't mean you support it, and is often done to emphasize how unlikely it is. Iapetus (talk) 10:37, 15 February 2017 (UTC) My point exactly, and I added the scare quotes to emphasize that this is not what I believe. But Jayron probably knew that. He just lies about everything I do to try to make me look bad. StuRat (talk) 14:42, 15 February 2017 (UTC)

(EC) A selection of relevant scholarly articles that may be of interest:

The Influence of Pornography on Sexual Scripts and Hooking Up Among Emerging Adults in College[42] (freely accessible)

“Bareback” Pornography Consumption and Safe-Sex Intentions of Men Having Sex with Men[43](paywalled).

Does Pornography Influence Sexual Activities?[44](accessible)

Does pornography influence young women’s sexual behavior?[45](paywall)

As indicated in our article, and mentioned by Jayron, there is no general consensus of any strong effect of pornography on sexual orientation, but many researchers have documented some effects of pornography consumption on sexual preference (in a non-orientation sense), sexual acts, etc. SemanticMantis (talk) 20:57, 14 February 2017 (UTC)

Yes, I meant sexual preference in the sense @SemanticMantis used the word, that is, not as sexual orientation (homo, hetero, and so on), but as a preference for sexual activities.Llaanngg (talk) 21:31, 14 February 2017 (UTC)

February 15

Diabetes type 2 - mechanism of the problem

What is the problem of diabetes type 2? I've said it because the pancreas don't secret enough insulin, and my teacher said it's not because of secretion of the pancreas since the pancreas secretes normal insulin levels but the problem is with the cells that they receptors for the insulin are covered by fats. He added that diabetes type 1 has to do with the fact that the pancreas don't secret enough insulin but in diabetes type 2 the pancreas does secrets enough insulin. Then I've asked him again, why diabetic type 2- patients used to take insulin if they have enough insulin in their body and he answered me that it is given to the patient when the diabetes is progressive after some years that the pancreas is already out of function. Now all this information is really against what I was told in the past by another teacher (that said what I did). What's true? 93.126.88.30 (talk) 00:11, 15 February 2017 (UTC)

There are many variations of diabetes. See brittle diabetes and insulin resistance, for example. StuRat (talk) 02:24, 15 February 2017 (UTC)

Our article Diabetes mellitus says that your teacher is correct-- type 1 is due to a bad pancreas, while type 2 starts with the cells' bad insulin reception but can eventually involve the pancreas going bad as well. Loraof (talk) 02:27, 15 February 2017 (UTC)

Yes, the article answers the question quite well. Type 2 diabetes begins with insulin resistance, where cells fail to respond properly to insulin. Now, as the disease progresses this can lead to pancreatic dysfunction, as the pancreas attempts to produce more insulin to compensate for this insulin resistance, and some type 2 diabetics can eventually require insulin administration. I get the feeling the original questioner is not a native English speaker. Wikipedia is available in many languages; if you have trouble understanding the English article, see if there are articles in your native language(s). --47.138.163.230 (talk) 03:49, 15 February 2017 (UTC)

By which mechanism sex is considered a risk factor for arteriosclerosis?

I listened today to a lecture in which the lecturer has said that there are 6 risk factors for arteriosclerosis: 1. food. 2. smoking 3. high blood pressure 4. obesity. 5. age 6. sex. I really don't have an idea on what it's based, because after googling I didn't find source for that. But my question is about sex. What does it mean that it's a risk factor and by which mechanism sex can be a risk factor for arteriosclerosis? (Maybe he wanted to say that they are general risk factor for life rather than for arteriosclerosis. It's not clear) 93.126.88.30 (talk) 00:25, 15 February 2017 (UTC)

Apparently, men are significantly more susceptible to it than women are. My source for that is this article.[46] Google the subject and there should be plenty of entries. ←Baseball Bugs ^{What's up, Doc?} carrots→ 00:30, 15 February 2017 (UTC)

• (edit conflict) Right, here "sex" means the sex of the person, not how much sex s/he has. Our article arteriosclerosis does not mention risk factors, but the related article Atherosclerosis#Risk factors does mention being male as a risk factor, with a citation. Loraof (talk) 02:21, 15 February 2017 (UTC)
  • This might be why "gender" is used more and more instead of "sex". ←Baseball Bugs ^{What's up, Doc?} carrots→ 02:24, 15 February 2017 (UTC)
    • OSHA form: Q:"number of employees, broken down by sex?" A: "None (booze is more of a problem for us.)" -Arch dude (talk) 06:11, 15 February 2017 (UTC)
    • No, thats wrong. It's because gender has social components, while sex (the property, not the act) is biological (if not always binary). --Stephan Schulz (talk) 14:14, 15 February 2017 (UTC)

^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ - Yes, thanks. The worst part is when people who should know better use "gender" as a sort of euphemism for "sex". SemanticMantis (talk) 15:27, 15 February 2017 (UTC)

Feynman Lectures. Lecture 48. Ch.48-4 . Refractive index < 1, phase speed > c [47]

...

In other words, for the slowest modulation, the slowest beats, there is a definite speed at which they travel which is not the same as the phase speed of the waves—what a mysterious thing!

— Feynman • Leighton • Sands, The Feynman Lectures on Physics, Volume I

What does he mean by "slowest"? Very low frequency of modulating wave?

A part from words Let us see if we can understand why to the end of the chapter is also obscure.

Now because the phase velocity, the velocity of the nodes of these two waves, is not precisely the same, something new happens. -- He considers x-rays. X-rays have a speed $v_{\text{x-rays}}=c/n$. How could it be that phase velocities are different? Even in the glass (or carbon) two x-ray waves must propagate with equal speed.

$\definecolor {myorange}{rgb}{0,0.38,0.52}\color {myorange}dk/d\omega =1/c+a/\omega ^{2}c$ -- When I express the formula (48.14) like this: $\omega ={\tfrac {1}{2}}(ck\pm {\sqrt {(ck)^{2}+4a}})$ and differentiate, I get: ${\tfrac {d}{dk}}\omega ={\tfrac {d}{dk}}{\tfrac {1}{2}}(ck\pm {\sqrt {(ck)^{2}+4a}})={\tfrac {1}{2}}(c\pm {\tfrac {c^{2}k}{2{\sqrt {(ck)^{2}+4a}}}})$. But Feynman got ${\frac {c}{1+a/\omega ^{2}}}$. Why? Username160611000000 (talk) 07:52, 15 February 2017 (UTC)

• Group velocity might help you. Tigraan^{Click here to contact me} 13:58, 15 February 2017 (UTC)

What type of person makes all the factory parts and programs them to work?

In a factory, everything seems to be automated. What type of person invents all the factory parts and programs them to work properly to create lots of things in a relatively short period of time? What skills and knowledge are needed? Are there any books about this matter? 166.216.159.7 (talk) 15:42, 15 February 2017 (UTC)