Wikipedia:Reference desk/Archives/Science/2017 February 11

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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)