Wikipedia:Reference desk/Archives/Science/2015 June 18

= June 18 =

hair loss breakthrough
Can I know whether the research as described in this article http://www.mirror.co.uk/news/technology-science/science/cure-baldness-hopes-raised-scientists-2476939 still going on ? Can you please tell me about the progress if you don't mind ? It looks awesome and revolutionary! — Preceding unsigned comment added by 54.240.197.233 (talk) 06:54, 18 June 2015 (UTC)


 * Consider the source. ←Baseball Bugs What's up, Doc? carrots→ 08:44, 18 June 2015 (UTC)


 * It's basically still a hair transplant, just where they clone the hair follicles before they transplant them. As such, it sounds quite expensive and inconvenient.  So, it might be technically feasible but still fail to catch on due to these reasons. StuRat (talk) 12:58, 18 June 2015 (UTC)


 * Ignoring the last two answers which don't address your question, you can find out more about it here and here. As there don't seem to have been any updates since 2013 I would assume that there is nothing further to report yet. Richerman    (talk) 13:17, 18 June 2015 (UTC)

Mothballs as a "preservative" for books
Is naphthalene a good idea for protecting valuable books being stored for a few years? I have several valuable books that I need to put away for a few years - due to lack of space in my current home for a suitable bookshelf. If I wrap the books in plastic (polyethylene) with a few mothballs in the package, would they be safe? If naphthalene is harmful to paper what is a better, but still easily obtainable, alternative? Roger (Dodger67) (talk) 09:32, 18 June 2015 (UTC)


 * I'm not so sure that (1) naphthalene would fend off bookworms; or that (2) storing a flammable material with paper would be a good idea. You might want to contact a local library or historical society and see if they have any good recommendations. ←Baseball Bugs What's up, Doc? carrots→ 09:38, 18 June 2015 (UTC)


 * Forget naphthalene, it is only a fumigant insecticide. Wikipedia (as always) has an article that may help. Environmental controls.--Aspro (talk) 11:45, 18 June 2015 (UTC)


 * The Library of Congress FAQ page may help. DuncanHill (talk) 11:53, 18 June 2015 (UTC)


 * I'd also be worried about moisture, so suggest you add a chemical desiccant packet to the bag. StuRat (talk) 12:54, 18 June 2015 (UTC)


 * I would be cautious about desiccants - books are damaged by dryth as well as dampth. DuncanHill (talk) 17:23, 18 June 2015 (UTC)

dogs recognizing dogs
How does one breed of dog (let us say a small dog, still knows that a large dog (let us say a great dane) is still a dog. They do not look alike, but still they act agressively and smeel the other as if they still know the other is a dog????

11:54, 18 June 2015 (UTC)200.42.22.13 (talk)


 * You provided your own answer: smell.   D b f i r s   12:14, 18 June 2015 (UTC)


 * Dogs determine each others' sex, age, health, reproductive status and social rank with just a sniff or two. Roger (Dodger67) (talk) 12:51, 18 June 2015 (UTC)


 * This question assumes that dogs do not assume that all animals are dogs. For all we know, dogs could see humans as weird dogs that walk around on two legs exactly like a dog should not do. 199.15.144.250 (talk) 13:52, 18 June 2015 (UTC)


 * Wolves need to be able to tell whether animals are prey animals, other wolves, or animals in some other category.  Humans don't smell like wolves.  Dogs do smell like wolves because they are wolves.  The suggestion that dogs or other wolves don't know differences in species is silly.  Wolves wouldn't have been successful in evolution if they couldn't recognize their own and others, and humans, in breeding wolves to be dogs, didn't breed species identification out.  They did breed in certain attitudes toward humans, so that dogs can treat a human as alpha, but the dog never thinks that the human is an alpha dog.  Robert McClenon (talk) 14:05, 18 June 2015 (UTC)
 * This is not a well-resolved issue, but there is increasing support for the notion that humans did not breed wolves to be dogs. Rather, the dogs domesticated themselves. See Origin_of_the_domestic_dog. The notion that humans intentionally used artificial selection and selective breeding to domesticate the canine is not entirely untenable, but it seems to be rapidly loosing favor. We may never know for sure, but I've done a lot of reading on the subject, and find the self-domestication theory far more compelling. SemanticMantis (talk) 16:00, 18 June 2015 (UTC)
 * If the domestication of wolves was self-domestication, or was primarily self-domestication, there is still no reason to think that dogs don't know the difference between wolves and humans. Humans certainly have not "dumbed down" dogs in the selective breeding of particular breeds.  Dogs, like horses, and unlike meat animals, are bred among other things for intelligence, and not knowing the difference between a wolf and a human is not intelligent, regardless of whether you are a wolf or a human.  Robert McClenon (talk) 16:16, 18 June 2015 (UTC)
 * Sure, I was just pointing out some interesting related info on the origin of dogs. And whatever happened in the distant past, selective breeding by humans has certainly been a very strong influence in the past ~1k years. SemanticMantis (talk) 16:43, 18 June 2015 (UTC)


 * For some references, see Dog, Dog_behavior, and Dog communication. What you are asking about is intra-species recognition, and it is very common in the animal kingdom. Even many plants can discriminate their own species from other plant neighbors and some can even tell whether a conspecific is closely related or more distant . Even If you want some scholarly sources, check out this  which describes how dogs can not only tell that animal is a dog, but also have strong abilities in kin recognition. Here  is a paper that discusses how dogs can even use smell to distinguish between human twins in some cases. I'm having a hard time finding explicit evidence that dogs perform intra-species recognition (probably too obvious to merit a study), but it is a necessary pre-condition for kin recognition, and there are numerous scientific reports of that. SemanticMantis (talk) 16:00, 18 June 2015 (UTC)


 * It's hard to comprehend just how much information a dog gets through it's sense of smell. Some estimates say that their noses are a million times more sensitive than ours.  The gulf between what we imagine can be conveyed that way, and what they must actually be able to detect is simply astounding.   Dogs have been trained to detect certain kinds of cancer in humans, to pick up the scent of drugs that are triple-wrapped in plastic inside a metal suitcase, to track the scent of sweat from day-old footprints from one specific human (and no other), wearing socks and shoes, in a forest full of confusing smells of all kinds.


 * To try to comprehend the difference this sensitivity might make, our eyes are capable of seeing a few million colored spots at once - but suppose you could only see one color at a time - the average color of everything in your field of view - it would be like detecting bright light with your eyelids closed. Well, the difference between a million-times-more-sensitive dog nose and ours is comparable to the difference between seeing with our eyes wide open and with them closed.


 * Telling whether another animal is a dog or not is childs-play (well 'puppy-play') compared to all of the extreme tricks that dogs can do with their noses!


 * SteveBaker (talk) 16:00, 18 June 2015 (UTC)


 * Anyone who has walked a dog should have noticed that they're quite capable of discriminating between dogs and various other size-overlapping species instantly, by sight, at ranges of tens of yards/metres when smell is clearly not a factor. For example: walks round corner, sees a small dog some distance away, exhibits usual con-specific doggy interest via body language and voice; walks round corner, sees a cat some distance away, takes off like a rocket nearly pulling walker off feet. {The poster formerly known as 87.81.230.195} 212.95.237.92 (talk) 16:30, 18 June 2015 (UTC)
 * How do you know they are doing it by sight? Dogs have rather poor vision (at least by our standards) - and it's very possible that this is scent.  Dogs have really good directional sense of smell too, they can determine direction from the tiniest differences in smell concentration in one nostril versus the other.  Interestingly, this is slightly true of humans too (See http://www.nature.com/neuro/journal/v10/n1/abs/nn1819.html). SteveBaker (talk) 18:05, 18 June 2015 (UTC)


 * Well, under some circumstances, it may well be difficult to determine which element of the sensorium is triggered first, but to be fair here, no matter how much more sensitive a dog's nose is (and these "millions of times stronger" notions are massive oversimplifications that make their way into popular discussions of the topic but which don't really accurately represent the nuances of the physiology and perception involved), a scent is always going to travel at a rate that is immensely slower than that of photonic/visual stimuli. And most dogs do in fact posses visual acuity that is more than capable of allowing them to recognize prey/playthings at a considerable distance.  It's color-depth (and a few other sublteties to vision which we take for granted) where their vision can be said to be less acute than ours, on the average.  It's hardly full-proof, but the best way to try to make an educated guess as to whether a particular dog perceives another creature in a particular instance through a particular sense is to observe their body language.  A dog catching a scent will generally keep its head low to the ground and will often keep it there for a moment, taking in the scent, before looking up and scanning on a horizontal plane, if it looks up at all.  A dog seeing another animal will typically freeze in place for a moment, its vision locked on said creature.  A dog hearing another creature will cock its head and attempt to position its ears (through the position of the head or the positions of the ear itself, to the degree that they have lobes capable of independent movement), to better ascertain the exact position from which the sound is emanating.  Regardless of which sense alerts the dog to the animal first, as soon as it has visual attnetiveness for the creature, this sense takes priority in directing its focus, since it provides the best real-time sensory understanding.  This is why most mammals, dogs included, and many other animals have a huge portion of their brain devoted to visual cognition.  S n o w  let's rap 03:04, 19 June 2015 (UTC)


 * Yes, visual recognition is more important in dogs than in wolves (though both have good eyesight). Experiments have been done to determine which sense predominates, and it is sight in dogs, but smell in wolves.  The difference is explained by the fact that a young puppy will open its eyes a week or two earlier than a young wolf cub.  Nevertheless, if a dog sees an unfamiliar breed, I suspect that it still uses its sense of smell to determine that the strange-looking creature is indeed dog and not some other species.    D b f i r s   07:22, 19 June 2015 (UTC)

DIY small-scale deacidification of books?
Is it feasible to neutralize the acid in the paper of (cheaply manufactured) paperback books, on a small scale, as a do-it-yourself project? If it is, how do you do it? --173.49.9.102 (talk) 12:29, 18 June 2015 (UTC)


 * I'd think alkaline fumes, like bleach fumes, might work. The two issues would be spreading the pages apart so the fumes could get to every page and sealing off the area so the bleach fumes don't damage the lungs of those in the area.  Liquid bleach wouldn't be a good idea, because that's mostly water and all that moisture wouldn't be good for the book.  Bleach tablets might work, although I don't know if you would get enough fumes from those.  Perhaps breaking them up into powder to increase the surface area might help.  Don't know if this has ever been done, though. StuRat (talk) 12:49, 18 June 2015 (UTC)


 * Bleach is not alkaline. Sodium hypochlorite has a pH of 7 and chlorine radicals readily form acids when binding with many other substances, so bleach would actually be counterproductive. Roger (Dodger67) (talk) 12:56, 18 June 2015 (UTC)


 * Chlorine bleach is highly alkaline: . Ammonia is another option, although again if it's diluted with water that moisture may be bad for the books. StuRat (talk) 13:02, 18 June 2015 (UTC)
 * LOL. Do note that Wikipedia pages carry a formal disclaimer that they are not advice, and so if you try StuRat's off the top of his head approach to "mass deacidification" and find your comics ... bleached, well, none of us assume any liability for that whatsoever. :)  (I note from that article that the approach has its risks, even when done in a serious way) Wnt (talk) 15:49, 18 June 2015 (UTC)
 * I was surprised that StuRat even considered bleach fumes, considering how corrosive bleach is. I actually considered ammonia (gas) before I posted the question. What I couldn't tell was whether it would be effective, whether the effectiveness would last, and whether it would cause other problems for the books being preserved. A small amount of ammonia is quite easy to generate. It is released by warming household ammonia. Confining it and recapturing unreacted ammonia seem relatively easy too. Does anyone know whether it will work, as a question of chemistry?


 * Another idea that I considered was dilute solution of antacid. I've seen it suggested for preserving newspaper. I have concern about the effect of water on bound paperback books. --173.49.9.102 (talk) 14:19, 20 June 2015 (UTC)


 * The reason bleach is so corrosive is it's alkalinity. If you use too much, then yes, this would be a concern.  A small amount, however. should be completely neutralized by the acid in the paper, same as ammonia.  Of course, getting this balance just right could indeed be tricky.  I'd start with some practice books I didn't care about.  Same applies to ammonia.  You should be able to test the book's pH before and after with litmus paper (although you would have to wet the sample with some distilled water, another reason to use books you don't care about). StuRat (talk) 14:37, 20 June 2015 (UTC)


 * (ECs) Serious Comic book collectors store their volumes in individual bags made of special plastic, which in turn are kept in boxes made of special cardboard to minimize acidification, and may interleave the pages with sheets of special de-acidifying paper. Also, libraries have batches of books treated by exposure to de-acidifying gases in chambers made for the purpose, run by commercial organisations (see our article Mass deacidification). Presumably the latter process could be recreated as a home project, but I suspect it wouldn't be trivial. See also our article Conservation and restoration of books, manuscripts, documents and ephemera for possible links to useful information. I really ought to look into it myself, having a personal collection of fiction and non-fiction amounting to an estimated 18,000 volumes :-). {The poster formerly known as 87.81.230.195) 212.95.237.92 (talk) 13:11, 18 June 2015 (UTC)


 * Have you had a look at Preservation (library and archival science) and in particular mass deacidification? I think you really need to have a buffer deposited rather than expose them to a reactive gas which will probably cause other damage. Nearly all cheap paperbacks and even many books from more than thirty years ago are liable to go brown and brittle very rapidly. Dmcq (talk) 13:29, 18 June 2015 (UTC)

1 2 Agent of the nine (talk) 15:13, 18 June 2015 (UTC)


 * I've come across mass deacidification processes during my search for a solution, and that's the reason I asked about small-scale deacidification specifically. Any more suggestions? --173.49.9.102 (talk) 14:19, 20 June 2015 (UTC)


 * Hm. I think it may be over hopeful to expect NASA or the National Bureau of Standards to help in the DIY project even if they were very helpful with the Declaration of Independence. :-) Dmcq (talk) 17:19, 18 June 2015 (UTC)


 * You might do well to contact a business like Talas that provides book preservation supplies or a bookbinder of which there are many, for example, in NYC who can advise you on the feasibility and cost of such a project. You can do the same sort of google search for Philly if that's easier, but I would call Talas first. μηδείς (talk) 21:46, 20 June 2015 (UTC)
 * Thanks for the links. --173.49.9.102 (talk) 02:36, 22 June 2015 (UTC)

Bearings are sticky - is this normal or has oil degraded?
I bought some of these bearings two years ago and am only ready to use one of them now. I took one from the wrapping and they're covered in something sticky. Further, the bearing rotates but it doesn't rotate freely - it feels like the sticky stuff is on the inside. Is this because the oil has degraded or are they meant to be like that? --78.148.104.139 (talk) 14:46, 18 June 2015 (UTC)


 * I'd certainly expect these kinds of bearings to spin freely and to not require additional lubricants or anything like that. I use these kinds of bearing in my laser cutters - and I've had spare parts sitting around in my workshop for more than 2 years that worked just fine when I came around to using them.


 * I suppose it's remotely possible that they were packed in some kind of anti-corrosion grease that you're supposed to remove before use. I'm thinking of something like Cosmoline (except that's unlikely to be the stuff they used unless these are ex-military parts).  Oil put into the bearing as a lubricant ought to have been protected by the rubber seals - if they are still airtight.   The ones I have don't require me to add or change lubricant - they are sealed for life - so they shouldn't get sticky.  I suppose that if you've stored them in some place where there are extremes of temperature, the rubber seals may have degraded and somehow leached some kind of sticky material onto the bearing surfaces.


 * The trouble with this kind of vendor on eBay is that you generally don't know where they bought their stock from - and it could be factory surplus or something...these bearings might have been sitting on a shelf for decades before you got them.


 * With open bearings, you could probably soak them in some kind of solvent to dissolve away whatever this goop is - and then re-lubricate them with some light machine oil. But these bearings are supposed to be rubber sealed - and if the seals are working, the solvent won't get into the bearings.  You'd also be likely to wreck the seals (if they aren't already wrecked), which would 100% guarantee that you'd have problems in the future.


 * Sadly, that ebay seller says that their returns policy isn't going to let you return them...but you could use ebay to ask the seller a question about them.


 * Incidentally - one super-cheap source for these kinds of bearings (although with a limited range of sizes) is to look for them where skateboards and rollerblades are sold - if you can use the sizes they have, you'll pay a quarter of what most engineering sources will charge for the exact same thing! Here in Austin, TX we have a skateboard shop, catering to the people who like to geek-out their boards with the fastest possible wheels, trucks, bearings, etc - and they have some REALLY good bearings for very low dollar.


 * SteveBaker (talk) 15:49, 18 June 2015 (UTC)


 * Perhaps the bad design is in that they used a rubber that the oil degrades? Some rubber does go sticky if it is very old. Dmcq (talk) 17:01, 18 June 2015 (UTC)


 * Okay, so I cleaned the bearing in "turpentine substitute" and now it turns freely. Perhaps the rubber seal is working just fine and this stuff coating them was just for protection as suggested? Anyway, thanks; I'll bear in mind that they may not function as expected - nothing bad will happen if they don't. :) 78.148.104.139 (talk) 17:36, 18 June 2015 (UTC)
 * That's good, sounds like it was just some protective grease like SteveBaker said. Dmcq (talk) 20:29, 18 June 2015 (UTC)
 * I worked in a tool shop for a few years and I would say what you had was probably perfectly normal. Some resistance in the bearing is not abnormal, they're generally not made to spin "freely". In a tool, a little bit of resistance in the bearing is going to be nothing compared to the stress of the working bit. Some bearings are rated to many tens of thousands, even hundreds of thousands RPMs, and in that kind of application you most certainly don't want to be lubricating bearings with machine oil, that is far too thin, in that kind of application you need a sticky grease. However, if you're using the bearings just in a "guide", or a rolling application then you are probably fine even if you don't lube the bearing at all. Vespine (talk) 23:17, 18 June 2015 (UTC)


 * Oh dear, this does not sound good. Tribology is a science. The manufacture probably applied the 'right' kind of grease for the application and now you have removed it. Viscosity can be important. Step-by-Step Grease Selection--Aspro (talk) 23:17, 18 June 2015 (UTC)


 * Note, some bearings need to be operated only when installed. An example are automotive wheel bearings. Improper mounted or not specified tightened screws cause an immediate and permanent damage to the balls inside. These bearings use not such kind of grease. These lubricated are lithium soap, MOS2 and graphite to cover a failure of the other lubricates. Some of these lubricates get thin like water when reaching 70 °C (~ 160 °F). When operating an new bearing several minutes, it is running better. -- Hans Haase (有问题吗) 09:30, 21 June 2015 (UTC)

People mistaking the gender of babies
Following on that dogs recognizing dogs discussion, something I've been wondering about is that some babies seem to get an inordinate number of people thinking they are of the opposite sex - despite the girls having pink dresses with butterflies on or the boys being dressed in blue and having a train type toy. It happens for all babies that some people just say he or she without thinking but for a few it is really noticeable to the extent it annoys the mothers. Any idea what could be the signs that put out this signal and override the conventions about colors? Dmcq (talk) 16:50, 18 June 2015 (UTC)


 * Human infants don't really have a gender (other than the ones assumed by a community), but they do have a sex. Gender norms are learned/put upon a baby, not chosen (poor wording; choice and preference certainly comes in at some age). And we all know pink is for boys, right? Pink. Anyway, Neoteny shows several physical ways in which (clothed) babies are sexually ambiguous. Many cultures have a notion that male is the default sex, our related article is at Androcentrism. SemanticMantis (talk) 17:50, 18 June 2015 (UTC)
 * That isn't true that Gender norms are put upon a baby, not chosen. Go ask transsexuals who believe they were born the wrong sex if that's true. Or go ask a parent if that's true. It's a commonly repeated thing, but it's utterly false. Babies most definitely do have a gender, it's just less obvious to someone who doesn't know the baby, that's all. Ariel. (talk) 18:58, 18 June 2015 (UTC)
 * I have to disagree with SM strongly, my niece was never coached in any way to be feminine, and she started spontaneously mimicking female TV characters, especially ballerinas, before she was two. Her parents are very progressive, and she has two older brothers, but she is radically feminine. μηδείς (talk) 19:24, 18 June 2015 (UTC)
 * Maybe we are having a problem with terminology. I was thinking primarily of young humans certainly under 1 year old, and probably younger. Surely most of us acquire a gender, through choice, exposure, community, etc. at some point as we grow up. There may even be a genetic or sex-influenced component. Surely most adults have a gender. But in scientific terminology, gender is primarily considered social construct, and is part of a person's personal self image - this is all explained in the article I linked above. As such, nobody under the age of 6 months (an infant), who hasn't even gotten object permanence fully sorted out, has any notion of whether they are more masculine or feminine, or who they might prefer sexually, or anything else that goes in to our concept of gender. Nothing I said contradicts the notion that some people believe they were born the "wrong" sex (gender disphoria), nor does it disallow some toddler starting to mimic female figures. Indeed, the mimicking of behaviors is one key way children learn, and that's why I put "learn" in my comment above. To my reading, both of your comments are perfectly congruent with what I wrote. You are both of course free to disagree with me and the information in our articles, but unless you can find some serious academic references that support the notion that an infant has a gender, I don't really find your complaints to be a very compelling criticism. If you want to think a 4 month old is clearly "masculine" or "feminine" because of what they seem to like, then knock yourself out, but that isn't really a scientific approach. To clarify, I think it's totally reasonable to say a 2-4 year-old child has a gender, but that's very different from claiming that a 2 month-old infant does. I was assuming the OP meant somethign closer to the latter than the former, as most people do not mistake the sex of most toddlers. SemanticMantis (talk) 22:55, 18 June 2015 (UTC)
 * I agree with SM. I also think it's foolish to assume parents can definitely completely avoid inadvertent gender related treatment, no matter how progressive they are. Also unless a person is living in a cult with zero outside influence, the influence of people besides the parents or general society can't be ignored, and again, it's foolish to assume there will be no gender related treatment, no matter how progressive anyone is. If someone is following TV characters, they clearly aren't in a cult with no outside influence. Nil Einne (talk) 15:43, 19 June 2015 (UTC)


 * Yup. Point in fact, it's a well-known observation amongst developmental psychologists that the influence of parents is not all that it is cracked up to be in popular belief -- this belief is understandable in that parents obviously want to believe they have control in shaping healthy habits and positive or desirable traits in their children, but does not really jive with the reality, when we study the outcomes of personality traits in an empirical fashion .  In reality not only does environment not play the overwhelming role most people intuitively expect, parents aren't even necessarily the major players in terms of the environment, as children often takes their ques more readily from their peers, or elsewhere in the voluminous amount of social influence tossed at them from all directions.   S n o w  let's rap 21:17, 19 June 2015 (UTC)


 * Well, think about it - what distinguishes male from female in traditional western world settings?


 * Body shape - hips, boobs, shoulders all have different dimensions in adult men and women. Not so in babies.
 * Hair length & style - babies don't have much hair - certainly not enough to style.
 * Clothing style - babies mostly wear the same stuff whether boys or girls - although admittedly, color choices may vary.
 * Size - men are generally larger, but babies are all over the map in weight and length in their first year.
 * Facial features - babies have round chubby faces - both sexes look the same.


 * The pink/blue color convention was a reliable guide for a while - but very often our &lt;1yr grandkid is wearing a "What happens at Grandma's house stays at Grandma's house" t-shirt and baggy pants that cover up the inevitable diaper, and yellow and pale green seem to be popular colors with both sexes. So it's not always helpful - and babies may also be wrapped up in blankets with much of their clothing hidden anyway.


 * Incidentally, you might be surprised to know that as recently as the 1930's, pink was not a 'girls color' at all - it was considered decidedly masculine (See Pink) - the stereotypical colors 'flipped' in an astoundingly short amount of time right around 1940! SteveBaker (talk) 17:52, 18 June 2015 (UTC)


 * Well yes exactly - there's very little or no difference between girl and boy babies except the clothes they wear, yet some that don't appear particularly different to me get people often saying he or she about them despite the clothes color. It isn't just them all being called he because sometimes it happens the other way round too. The latest case I'm thinking of is a little baby girl of two months and the only difference I can see is she is more active and alert than most. I don't see how people could spot that immediately if they don't notice the pink and frills or even a pretty headband with a flower design like a flapper. Dmcq (talk) 18:50, 18 June 2015 (UTC)


 * Like Ariel writes above; gender is not in your clothes, hairstyle, body type and whatnot. It's not in your upbringing either. It's in your head and in your heart. As a transsexual I know what I'm talking about. I was a boy even when I dressed and looked like a girl, and was brought up like a girl. Babies of course have a gender, only that they can't tell us. ... I agree though that both boys and girls LOOK the same up until a certain age. /Kristian — Preceding unsigned comment added by 176.71.52.77 (talk) 22:47, 18 June 2015 (UTC)
 * Yes, masculinity and femininity were widely believed to be acquired behaviours until the sorry case of David Reimer proved otherwise. Alansplodge (talk) 23:23, 18 June 2015 (UTC)
 * I don't think the David Reimer case really proved anything except how dangerous a botched circumcision is and what a stupid idea it was to try and force a gender role on him and to do reassignment surgery at such a young age. For starters a single case can rarely prove anything whatever happens and this should have been (although unfortunately wasn't so much at the beginning) considered whatever the believed outcome. More importantly, he hardly had a typical childhood with the therapy sessions, whatever the truth about what went on in them (and whatever the reason for some of them whether stuff Money didn't know about or just bad ideas on his part), parents who realisticly were unlikely to treat him anywhere like the same as they would have a girl, the natural problems that come from reassignment surgery even more so given the techniques then etc. (Note that even overcompensation could easily have been a bad thing in many ways.) Children do sometimes have severe psychological problems while growing up including fitting in, they don't normally find out they were actually born with a penis which was destroyed by circumcision and they then had reassignment surgery and attempt was made to forcely raise them as a girl. (And to be clear, I'm not saying they shouldn't have told him, rather he should have known much sooner, without having had any reassignment so he could decide for himself what he wanted.) Also the foolish attempt to force a gender role only happened sometime between 7-22 months. This isn't to suggest that gender disphoria isn't real, it obviously is, but simply what I said at the beginning i.e. that we can't really learn much about the acquired vs genetic, or even acquired after birth vs acquired before birth from this case. We can perhaps say that it appears there may be a component which is present by 2 years of age or so, but even that should be treated with caution. And just to avoid any controversy, I should be clear I'm not saying, gender is acquired (although I do think it is unlikely there isn't some component that is acquired) or that it doesn't exist, rather that it's unlikely we'll know for a long time yet and we shouldn't read too much in to the scant evidence, but instead take the best lessons to learn from the little we do know, which does appear to be closer to what Milton Diamond advocates then John Money. Nil Einne (talk) 15:43, 19 June 2015 (UTC)


 * I'd say it's rather inaccurate and reflects a dubious understanding of neuropsychology to claim that babies have a gender that "they just can't communicate to us yet". They simply are not, at that stage of development, in possession of a brain and neurocircuitry capable of processing and actualizing gender roles.  The human organism at that age has more or less identical needs, regardless of the biological sex, and a very simple and mostly universal array of social and communication ques with which to interact with other people, relative to a mature individual.  It is also absolutely true that at this point they already have a degree of genetic determinism which will have a powerful innate influence on how they will process gender as they continue to develop and that these biological factors combine with environmental ques to determine the ultimate identity of the individual.  But just because a person identifies with a gender that some see as incongruent with their biological sex (or more accurately, their external sexual phenotype) does not mean they "had that gender all along" from the point of birth or conception.  It only means that its possible they were always biologically determined to incline towards that identity, and that their upbringing could only influence those traits so much against that natural inclination.  For more details on this distinction, see SemanticMantis' informative post above, and the articles to which he links.   S n o w  let's rap 00:32, 19 June 2015 (UTC)
 * Thanks, well put. Also worth pointing out nature vs. nurture, and that gender can be influenced by both. The sad case linked above doesn't do anything to disprove environmental factors, nor does the existence of somebody who freely chooses to change gender as an adult disprove the existence of genetic factors. Kristian's comment above is completely in line with sex not being the sole determinant of gender. The other thing that might be tripping up the conversation is there is one sense of gender that is usually completely assigned - on the day a baby is born XY with normal genitals, he is called a boy, and implicitly given a masculine gender (and vice-versa for XX/Female, at least most places in the modern western world). That is a bit different from the notion of gender that is tied up with self perception, gender performance and sexuality of adults. SemanticMantis (talk) 00:50, 19 June 2015 (UTC)
 * And there's further both generational and contextual divides in the factors you reference with regard to how "gender" is semantically utilized and interpreted. Before contemporary perspectives and scientific advancement began to disentangle them, "gender" was often used in a fashion where it was much more interchangeable with (biological) "sex", and in many cases in common parlance, this perception persists.  It wasn't until the social and behavioural scientists of the second half of the last century started to feel a pressing need to have two terms (one which applied to social identity and one to overt physiology) that the terms started to take on their more distinct meanings, and even then it wasn't until the last decade (and the last few years in particular) that this distinction truly started to permeate into general usage, and that transition is still far from complete and the lines between the two can be tricky on occasion even for those who use it consistently in professional or deeply personal contexts.   The whole situation is further complicated by the fact that, though we increasingly use these terms with a more nuanced understanding of the biological implications, the academia which first developed it's usage was rooted in rather soft and dubious social science.  Specifically, some of the "radical" voices of second-wave feminism used the gender/sex dichotomy as an underpinning to their arguments that gender was a completely socially-constructed phenomena, and that, if not for entrenched culture, there would be little or no distinction between the sexes.  That extreme interpretation is not taken very seriously by cognitive scientists today, but it's proven surprisingly tenacious in some outlying veins of sociological "study".  This notion has had consequences for those with gender dysphoria today that few would have anticipated at the time, since many people continue to regard gender as a social construct and oppose the notion that a person might be hard-wired to tend towards a certain gender (and that this wiring might at times be inconsistent with their genitalia and secondary sexual characteristics).


 * There's another point you touch upon which I think warrants some discussion as well, and that's the interplay between innate/genetic tendency (I use this in place of "determinism" for reasons that I'll shortly elucidate on) and environmental influence -- that is "nature vs. nurture".   For the longest time, as we all know, arguments against the acceptance of non-heteronormative sexualities and transgendered identities hinged on the notion that they were "against the natural order" and thus the question of whether LGBT persons chose (or were socially influenced towards) their preferences or whether they were genetically programmed in this regard and had no choice in the matter, became one of the central ideological battlegrounds around which their fight for acceptance and rights were conducted.  But research is telling us increasingly that in the fight against the intolerant "these people just aren't natural" arguments, the opposing perspectives may have over-corrected when they began to assume that sexuality and gender were completely determined at birth, and that environment cannot make even a dent on the resulting sexuality or gender identities of a mature person.  These are hot-button topics (especially with regard to transgender identities of late) and few researchers want to be amongst those who publicly talk about the notion that sexuality and gender identity may not be as firmly hard-wired as has been implied, for fear that they might be mistaken for the intolerant voices of the past.   But there's an increasing tendency amongst those who research sexual orientation through the lens of biology to say that many people are born not with a set specific biological determinism to be straight or gay, but that rather they are born with "spectrum" of possible sexual identities, and that environment then fine-tunes the specifics.   What's more, the identities they do "lock into" in these regards are not necessarily permanent. As global perspectives towards homosexuality change, and more people live freely and openly with their non-heterosexual decisions, interesting data is starting to emerge.  There are some people who seem to move back-and-forth between being gay and straight in different periods of their life.  Nor are these people exactly "bisexual" in the traditional sense -- they often report feeling exclusively attracted to one gender and then another during different periods of their lives.  Further, we've observed similar tendencies in other animals species for a long time, and noted that these tendencies tend to change with the environmental factors around them (habitat, local population size and so-forth), though obviously this is not quite the same thing as the complex social expectations that partially define the sexual environment of humans.


 * The extent to which gender identity parallels these ambiguities is unknown; we're very much at the beginning of studying these phenomena in an empirical fashion, despite the fact that they've surely been with us since the advent of our species (and probably much, much father back into our distant ancestry). But we do know that there are a great many people who secretly identify as transgender to greatly varying degrees who never feel compelled to transition or even broadly acknowledge their "alternative" gender identity.  My personal educated guess is that "gender fluid" identities (to use the new buzz terminology) are more common in the inner lives of many people than has traditionally been assumed, and certainly we see a lot of experimentation in youth, though some are shamed out of it, and others pass through it relatively quickly without any particular pressure.  But bringing all of this back around to the original topic of discussion, I think (as with most every other domain of human behaviour and expression) people have artificially divided "nature and "nurture" into two distinct and competing forces, in a manner which does not jive with our more scientific understanding of the process of individual development.  In truth, they are one process, not easily separated if you really want an accurate and complete story of how a person's propensities and outlooks are formed.  But the separation of these processes into two schools of thought has proven useful to those who want to argue these topics from ideological perspectives, and so the debate persists in these terms of oppositional forces.  But it's going to be increasingly recognized as an untenable way of characterizing human development, moving forward.   S n o w  let's rap 02:39, 19 June 2015 (UTC)
 * I have no idea why people have problems with this, so I've just given up and gone with Hanlon's razor. shoy (reactions) 13:50, 19 June 2015 (UTC)
 * I don't think even that principle applies, since it's not a matter of stupidity to fail to pick up on gender-specific ques in the faces of male and female babies, because in reality these ques don't really exist.  S n o w  let's rap 21:21, 19 June 2015 (UTC)
 * If someone sees the drawing of the Gerber baby, for example, and doesn't know anything about its history, I can't imagine how someone could know the sex of the illustrated child. ←Baseball Bugs What's up, Doc? carrots→ 06:33, 20 June 2015 (UTC)

Ambulance training
Are ambulance crews trained to deal with panic attacks? I heard that much ambulance time can be wasted dealing with them as they are not life threatening. 2001:268:D003:EA32:38E8:7ECB:6307:9367 (talk) 20:53, 18 June 2015 (UTC)
 * I see absolutely no reason to think the answer to your question is anything other than yes of course they are. It would not necessarily be immediately obvious if someone is suffering a panic attack or something more serious (like a heart attack) and in that situation I think the "better safe than sorry" rule applies. Just doing a quick google it seems like it's not unheard of for a panic attack to land people in hospital. Vespine (talk) 23:01, 18 June 2015 (UTC)
 * true but many ambulance services worldwide are campaigning for people to stop calling them in non life threatening case as it uses up resources. Surely a panic attack would fall under that. 106.142.246.1 (talk) 23:05, 18 June 2015 (UTC)


 * Well, I found several ambulance services that have advice on how to deal with them their websites  - perhaps they're hoping that you will use Google instead of calling them. It has been included in every first aid course that I have attended (I've lost count though - the first was in 1976) so on that basis I believe that the answer to your question is "yes". Alansplodge (talk) 23:18, 18 June 2015 (UTC)
 * Really? It's never been covered on any I've attended. 106.142.246.1 (talk) 23:30, 18 June 2015 (UTC)
 * This is sort of an unrelated side question but any idea why when I signed my original question it gave a weird IP address? 106.142.246.1 (talk) 23:32, 18 June 2015 (UTC)
 * Your first posting has an IPv6 address, but your subsequent postings have IPv4 addresses. Which type of address you get is determined by your ISP and networking hardware. Tevildo (talk) 23:45, 19 June 2015 (UTC)
 * Well that's fine if you know for certain that someone is suffering from a panic attack. However, if I was confronted with someone suffering from symptoms such as: shortness of breath, heart palpitations or a racing heart, chest pain or discomfort, sweating, numbness or tingling sensations etc. I would call an ambulance and let the professionals decide whether they were suffering from a panic attack or a heart attack. Richerman    (talk) 23:32, 18 June 2015 (UTC)
 * Indeed, a Google search brings up several cases of heart attacks being misdiagnosed as panic attacks by paramedics or ambulance technicians, sometimes with fatal consequences. Alansplodge (talk) 01:59, 19 June 2015 (UTC)
 * There is no way that anyone will advise a person to call anything but 911/999 if they believe it is a medical emergency. Panic and anxiety are precursors to a number of physical ailments such as cardiac arrest.  It's perfectly acceptable to treat a patient as having a heart attack even if it later turns out to be a panic attack.   They will be conservative since misgiagnosing a panic attack as a heart attack is inconvenient but misdiagnosing a heart attack as a panic attack is fatal.  --DHeyward (talk) 00:31, 21 June 2015 (UTC)

Ivory-bill woodpecker
Where are ivory-billed woodpeckers currently being seen? — Preceding unsigned comment added by Kcinrawm (talk • contribs) 22:01, 18 June 2015 (UTC)


 * Nowhere with any certainty. See Ivory-billed_woodpecker. We have no strong evidence that the bird is not extinct. There have been some unconfirmed sightings claimed (which may not be the bird at all) in 2005-2006. If there are any birds left, they are most certainly currently below the Minimum_viable_population. One place to look would be along the Choctawhatchee_River. If you can find one and lead a biologist to it, you can win a $50k prize. Sadly many experts believe it is just a matter of time before they can be officially declared extinct :-/ SemanticMantis (talk) 22:30, 18 June 2015 (UTC)


 * There are stuffed specimens in some museums, and that's about it. ←Baseball Bugs What's up, Doc? carrots→ 16:58, 19 June 2015 (UTC)

Impact of water pressure on a scuba diver
Can someone help me understand the impact water pressure has on human scuba divers? I'm curious and have a few questions about what happens at typical scuba underwater depths.

When a diver is underwater, does the water above a scuba diver effectively push down on the diver? If so, does that pressure act to drive the diver deeper into the water? If not, why not?

I also recall hearing that water pressure can impact the lungs and lung capacity. I believe the comment implied that the lungs essentially shrink based on the water pressure. Can someone elaborate on what impact (if any) water pressure has on a divers lungs and how that occurs? Do the lungs actually shrink, or does it have more to do with the water pressure causing a diver's chest to be compressed? 68.96.8.201 (talk) 23:26, 18 June 2015 (UTC)


 * The reason the diver is not pushed downwards is that the pressure acts on him/her from all directions - not just from above. There's a description of how pressure affects divers here. Richerman    (talk) 23:54, 18 June 2015 (UTC)


 * Scuba stands for self-contained underwater breathing apparatus'. The regulator delivers air at the same pressure as the surrounding water so that the lung capacity (volume/size) remains the same as it is on the surface. Although the water above the diver has mass and density, the water below has mass and density also, and both cancel out. Therefore,  the water above doesn’t force the diver deeper. A free diver (i.e. holding his breath as he dives down from the surface) will suffer reduced lung volume as he descends and will find it becoming easer to swim down as he loses the buoyancy from his shrinking lungs. --Aspro (talk) 00:05, 19 June 2015 (UTC)


 * It is also important to know that because SCUBA regulators deliver air at the ambient pressure, they are necessarily delivering a lot more molecules of air at depth. It gets complicated, but you use up about twice as much of your tank's content at double the depth.  The practical aspect is that greater depth = less dive time, and that's even before you have to allow for slow surfacing.176.46.102.175 (talk) 02:14, 19 June 2015 (UTC)
 * But it's more complicated than that, because each breath at great depth brings more oxygen (and other) molecules into your lungs. So, you don't need to breathe as often!  However, for safety, a diver needs to breathe regularly: this prevents pulmonary hyperinflation.  Also, at great depths (high pressures), the pesky other molecules in air also get into your blood stream at a faster rate.  Specifically, nitrogen enters solution in your blood and tissue, and if you are not careful, you can get the bends (the most serious problem associated with decompression sickness).  Unusual gas concentrations in your blood can also cause nitrogen narcosis and oxygen toxicity.  Regular divers ("SCUBA divers" in the terminology of NAUI) are usually limited by breathing gas pressure: they run out of gas after about half an hour to one hour, and it's time to come back up.  The next tier of advanced divers ("Enriched Air, Nitrox Diver" in NAUI's certification scheme) may dive deeper a different dive profile, and their safety is limited by nitrogen narcosis: so, they put less nitrogen and more oxygen in their air tanks.  Divers who go very deep for a long time are usually limited by having too much oxygen (not too little gas pressure)!  This is why deep divers breathe trimix gas.  They put less nitrogen and less oxygen in their tank, and fill the rest with helium.  This mixture is not usually safe or comfortable to breathe at atmospheric pressure, so these divers may use ordinary compressed air or Nitrox to start their dive, and then switch tanks at the bottom.
 * The air in a skin diver's lungs does shrink: as they dive deeper, their lungs squish and become very small. A SCUBA diver is constantly equalizing the pressure in the lung using the SCUBA regulator: so the lungs should not change size significantly - that would only happen if you hold your breath, which is an unsafe diving practice that can lead to pulmonary hyperinflation.  However, the rest of a diver does compress at depth.  At only thirty feet, your neoprene weight belt is usually too loose because your body has physically shrunk: but if you tighten up the gear, it will crush you when you return to the surface!
 * SCUBA diving is complex: there is a lot of technique, safety procedure, and physiology related to pressurization (among lots of other important knowledge!) that you must learn thoroughly before you can safely dive.
 * Nimur (talk) 06:38, 19 June 2015 (UTC)
 * You may want to review nitrox diving. It extends dive times in shallower depths.  It never allows deeper dives than regular air because the enriched oxygen is toxic.  It only extends the time allowed at a shallower depth since the reduced nitrogen helps with the bends.  Toxic partial pressures of oxygen limit dive depth, nitrogen limits dive time.  Nitrox allows custom, shallow depths with maximum time since you can basically go to the oxygen partial pressure limit at the cost of depth. A nitrox chart should bottom out before compressed air.  --DHeyward (talk) 08:42, 19 June 2015 (UTC)
 * Yikes, what I wrote earlier was not right! Thanks for correcting me.  Of course, both nitrogen narcosis and oxygen toxicity will limit your dive, so your dive profile needs to be constructed within both limits.  Always check your dive tables and consult your dive master.  The summary DHeyward provided is more in line with the textbook answers.  On the flip-side, the deepest dive I ever did was a Nitrox dive, so my mental heuristics are backward.  If we were going for maximum depth in a dive profile, and were limited only by the dive depth, then compressed air would typically take you deeper than enriched air, but you'd have less time to get there and less time to get back.  Nimur (talk) 12:13, 19 June 2015 (UTC)
 * For just buoyancy, the neoprene suit is buoyant as well as lungs above the surface (and fat). Divers wear weights to compensate but this usually doesn't change the positive net buoyancy at the surface.  At a certain level below the surface (usually around 5-10 feet in my experience), the density of air in the lungs is high enough that buoyancy changes to more neutral to slightly negative.  Breathing makes the diver rise and bob at the surface.  This diminishes at depth so that inhaling doesn't change the divers depth like it does near the surface.  I can feel the depth where inhaling no longer rises and the tendency is to sink.  Neutral buoyancy is the goal so the diver is not fighting the sink or the rise. In an emergency, there is a rapid inflation device as well as a quick release of weights but that's not a recommended ascent.  Beats drowning though.  --DHeyward (talk) 08:29, 19 June 2015 (UTC)

Thanks everyone for responding, thats interesting info! Nimur, I'm not sure if that link to skin diver was the intended target? Also, any suggestions on where can I learn more about the lung squishing you describe? This is all just curiosity, I'm not planning on diving myself. (OP, but on a different machine)128.229.4.2 (talk) 13:30, 19 June 2015 (UTC)
 * Sorry, our article on the topic is freediving. I will fix my link.  Nimur (talk) 14:27, 19 June 2015 (UTC)

Do window coverings have an impact on A/C usage?
I got an email at work asking employees to close the blinds on hot days - particularly when the sun is directly shining through the window - in an effort to reduce air conditioning costs. That made me wonder - does closing blinds really have a noticeable impact on an air conditioner's workload? Assuming that window coverings are just regular fabric material of a grayish color, will closing them really effectively keep more heat out of the room? Or does it just cause the window coverings themselves to absorb the sun's rays and heat up vice the entire room absorbing the sun's rays? Wouldn't the air conditioner have to do roughly equivalent work to cool down the window coverings that absorb the sun's rays as it would if the coverings were opened and the objects in the room absorbed the suns rays?

I guess my question boils down to this - does it really matter what object inside of a room gets hot by absorbing the sun's rays? Be it the window coverings, or the desk opposite the window, wont the air conditioner have to contend with either circumstance in a similar manner?

I'm sure specific conditions make a difference, but i'm just curious about any answer anyone may have in general. 68.96.8.201 (talk) 23:27, 18 June 2015 (UTC)


 * If the window covering reflects solar energy (instead of absorbing it), then there is less net total energy entering the room. Nimur (talk) 23:42, 18 June 2015 (UTC)
 * And unless your shades are made of Vantablack, you'll be reflecting some non-trivial radiation. SemanticMantis (talk) 00:24, 19 June 2015 (UTC)


 * As you say, specifics may have a noticeable effect on the answer to your question, particularly the qualities of the windows, the blinds, the specific temperatures and the space involved. In general, though you do raise a factor that can significantly mitigate the benefit in efficiency expected from closing the blinds, but there are properties of thermal conduction in complex systems you haven't necesarily accounted for, all the same.  Consider, for example, that the blinds may absorb a great deal of heat but not release all of it into the inner-more space to have a significant impact on the processes of cooling the air therein. A great deal of the heat striking the blinds may be radiated back in the direction from which the photons emanated, traveling back through the glass or remaining for a time in the space between the glass and the blinds. Depending on the material qualities involved, a significant amount of heat might be kept isolated in such a fashion until a time of day when the building is no longer as heavily occupied (and this air conditioning is not as warranted) or until the overall heat in the complete system of both the building and its external environment drops (as night approaches, for example).


 * There's also another factor that doesn't so much influence the overall amount of thermal energy involved, but will still play a major role in the degree to which AC is employed. That is, in the majority of cases, AC is utilized not because the building itself needs to be kept at a particular temperature (though certainly there are many cases where this is a practical necessity) but rather more often for human well-being and comfort.  In the case of the blinds being open, the light and accompanying heat can travel farther into the inner environs and heat up individuals directly. Although these people represent only a small portion of the mass involved in the total system, their particular heat is a defining factor that goes forward to exert considerable influence over how the AC is then utilized, particularly in systems that are not fully automated.  And sometimes its not even so much a factor of their core temperature significantly changing as it is a matter of perception of heat.  Considering all of the factors above, I'd say the answer is really "it's highly dependent upon the circumstances" (but then you clearly already realized that), but I would say there can easily be circumstances where the overall efficiency of a system could be marginally significant enough for the blinds issue to warrant the attention of someone managing a large enough space, especially if the building is not particularly well weatherized.  Of course, there is also something to be said for the corresponding psychophysiological effects of decreased natural lighting on the overall efficiency of a human system, but that's another topic altogether.  S n o w  let's rap 00:10, 19 June 2015 (UTC)


 * Here it says: Internal venetian blinds 55 – 85%. Even without A/C we close the binds and curtains for this very reason. Walk into a room where you haven't done so and it is noticeably hotter.--Aspro (talk) 00:23, 19 June 2015 (UTC)


 * , I'm not getting a working link for that URL; perhaps you should double check if this is the working address you intended to add. (Feel free to delete this post of mine when you correct the link, to save space, if you are so-inclined.)  S n o w  let's rap 00:53, 19 June 2015 (UTC)
 * Thanks. The link should now work--Aspro (talk) 16:03, 19 June 2015 (UTC)
 * If the sunlight is turned into heat at the window, much of that heat will radiate right back out the window, and not enter the rest of the room. Still, I agree that white blinds are better.  This is why most blinds are either white or light colored. StuRat (talk) 02:45, 19 June 2015 (UTC)


 * I have no reference for this, but surely the difference is between light and shade? Isn't a patio in the shade cooler than the same patio in full sun? I know it's purely intuitive, but there must be some reference for this that cuts the mustard with the scientific community (I presume my OR from the University of No Shit Sherlock doesn't count!) --TammyMoet (talk) 05:34, 19 June 2015 (UTC)


 * Well, the IPs question is predicated on the fact that the blinds themselves are not shaded from anything, and as they heat up, the energy contained within them is eventually transmitted, at least in part, to the nearby environs. The crux of the answer to their question is that, yes, some of this thermal energy is delivered into the complete system eventually, but some is reflected back out the window and some is held in place (in the blinds themselves or between the the blinds and the windows) long enough that it creates a (small, but in some cases noticeable) reduction on the overall energy required by the AC system to maintain a particular temperature during the hours of operation -- until such time as the ambient temperature surrounding the system cools down or the need for cooling becomes unnecessary for whatever practical reason (i.e. an office building vacated at the end of the day).  S n o w  let's rap 06:31, 19 June 2015 (UTC)


 * I'm a bit surprised that no one has pointed out that it's not just reflection that sends heat back out. When the blinds heat up, yes, they radiate heat, but they radiate it equally in both directions.  So even if they were perfectly black and didn't reflect at all, they would still reduce the net rate of increase in the heat energy of the room, by radiating it back out the window.
 * This is the principle used in heavy-duty cryogenic insulation. You can use a Dewar flask to hold your LN2 or whatever, and it works because there's no (or very little) conduction of heat across the vacuum gap, and you reduce the radiative transfer of heat by making the walls mirrored. But still, there's going to be some radiative transfer.
 * You cut it down by having multiple vacuum gaps, instead of just one. Take the simplest case where you split the vacuum gap with just one extra wall.  When the outer wall heats up and delivers a photon into the vacuum gap, it doesn't matter how wide the gap is, it will get to the other end.  But if it hits the middle wall, then the middle wall heats up by the equivalent of one photon, and when it radiates one back, it's equally likely to go in either direction.  If it goes inward, then it's no different from the case where there's no middle wall.  But if it goes outward, then you're back to the outer wall, and various things can happen, none of them worse than the case without the middle wall.  So you slow down the overall rate of heat transfer. --Trovatore (talk) 06:51, 19 June 2015 (UTC)


 * Not to be persnickety or touchy or anything, but I did reference the fact that heat is radiated in both (or rather, all) directions, or at least I alluded to it by noting that some of the heat is transmitted back out the window and some retained in the space between the blinds and the window.  S n o w  let's rap 07:14, 19 June 2015 (UTC)


 * You said "reflected", not "radiated". It's possible you meant to include re-radiation; if you say you did, then I'll certainly take your word for it.  But you didn't say it.  In the context where Nimur had said If the window covering reflects solar energy (instead of absorbing it), then there is less net total energy entering the room, and SemanticMantis followed up by pointing out that there would (almost) always be reflection, I thought it was worth mentioning that, even if the shades are perfect black bodies, absorb all the incident light and reflect none of it, they still slow down the heating of the room. --Trovatore (talk) 07:21, 19 June 2015 (UTC)


 * (EC) Well, the light is reflected, but the transformed energy generated by an absorbed photon is what generates the heat, so it could only end up there via radiation -- that's why I thought the radiation itself implicit the system I describe. Though to be fair, I suppose its also the case that the glass and the air itself also absorbs some heat.  But in any event, all of this raises a notion that is worth repeating again in answering this question -- namely that, aside from the heat that gets transmitted back out the window, or otherwise into the external environment, the overall combined thermal energy of the building and its occupants remains constant.  It's simply a matter of how long you can keep some of that energy isolated from the air and other internal environs that actually matter to the occupants enough that they use the AC to begin with.  If they were going to spend the rest of their lives in that building and the solar radiation was constant, then the effect of the blinds would be even drastically more negligible.  But eventually the day ends and maybe the people also leave the building at the end of the day, so even if the blinds are opened, releasing the air trapped between, and even the blinds radiate all their remaining heat until they reach rough equilibrium with their surroundings, it doesn't really matter so much anymore to the efficiency of the cooling system.   S n o w  let's rap 07:14, 19 June 2015 (UTC)


 * Oh, actually on re-reading, you did say something of the sort in your first contribution. But kind of in the middle of a longish discourse.  --Trovatore (talk) 07:27, 19 June 2015 (UTC)


 * Hah, yeah... Maybe I have erred to the side of verbosity in my contributions today. :]  S n o w  let's rap 07:36, 19 June 2015 (UTC)


 * Trovatore also seems to have missed my contribution, where I talked about the heat radiating back out the window. Am I typing in invisible ink ? StuRat (talk) 14:27, 19 June 2015 (UTC)
 * I did miss your comment, Stu, sorry about that. --Trovatore (talk) 19:41, 19 June 2015 (UTC)

very interesting reading - thanks to everyone for their responses. (OP on a different IP) 128.229.4.2 (talk) 15:10, 19 June 2015 (UTC)


 * Happy to help -- I like these kinds of practical every-day context thought experiments. :)  S n o w  let's rap 22:18, 19 June 2015 (UTC)


 * The effect is depending on the size of the window. The sun is emitting about 1 kW per square meter or 10 square feet. Much is heat, some is light. Intelligent achritecture arranged glas the way to have much light into the room and less direct sun exposure into the room when summer or in an hot region like a desert or near equator. Feeding the air conditions radiator with cold air taken from a shadow saves also energy by making the ac work on a smaller difference of temperature. -- Hans Haase (有问题吗) 09:11, 21 June 2015 (UTC)
 * Automotive industry is offering special glas to keep the heat out by filtering infrared light. This is very commmon on in the US sold vehicles. Some others just offer colored glas with no effect on infrared light. -- Hans Haase (有问题吗) 09:14, 21 June 2015 (UTC)