Wikipedia:Reference desk/Archives/Science/2016 January 21

= January 21 =

Is it true a lot of people with down syndrome sound German/Russian when they talk?
I wonder if they do. 208.181.190.136 (talk) 03:35, 21 January 2016 (UTC)


 * Sounds like a myth. This review of Downs Syndrome speech impediments mentions no such thing, though perhaps that would be a useful place for you to learn why people with Downs often sound the way they do. Someguy1221 (talk) 05:44, 21 January 2016 (UTC)


 * Yes, it is true that a lot of people with Down syndrome sound German or Russian when they speak. The huge majority of them are found living in Germany and Russia. English speaking people with Down syndrome do not sound German or Russian. In the UK they speak English with what ever accent they have absorbed from their social mileau. This is based on personal research (shock - horror) from meeting dozens of people with Down syndrome. I have often wondered why Canadian people sound like Americans with a Scottish grandfather. Richard Avery (talk) 07:58, 21 January 2016 (UTC)


 * My American friend has two Scottish grandfathers, and doesn't sound one bit Canadian. μηδείς (talk) 17:34, 21 January 2016 (UTC)

Anti-animal armor ?
For zookeepers and others who need to deal with potentially dangerous animals, wouldn't having a suit of armor that could protect them be a good idea ? Seems like that would be preferable to using tranquilizer darts on all the animals in an enclosure, say if the zookeeper needs to go in and retrieve something dropped into it accidentally. So, has this approach ever been tried ? StuRat (talk) 04:03, 21 January 2016 (UTC)
 * Tranquilizers are not without risk, they generally don't tranquilize animals unless they have a very good reason to, I doubt something being dropped accidentally into an enclosure qualifies. I think most enclosures would have a "locked" area where the animal can be herded into. Also I doubt there is a suit of armor that could do much to protect someone from a really powerful animal like a tiger or a rhino. Vespine (talk) 05:33, 21 January 2016 (UTC)
 * Also there are those Bite suits that are used for training attack dogs, such as for the police department. Surprised I can't find a wiki article for it. Vespine (talk) 05:36, 21 January 2016 (UTC)
 * Such suits have been built, notably by Troy Hurtubise who won an ignobel prize for actually testing his invention. I'm going to make a wild guess that most sane people don't want to actually put such suits to the test. Either the thing that's been dropped is not important enough to do anything but wait for the animals to wander into the lockable part of the enclosure, or the thing is so important you have to get it out right away and use tranqs. Someguy1221 (talk) 05:40, 21 January 2016 (UTC)
 * And, body armor is really heavy, and limits your movement. Ask anyone who's worn a bulletproof vest. On top of that it still won't do much to protect you against blunt trauma (this is why maces and other bludgeoning weapons were useful), which could easily be inflicted by many large animals. Armor won't stop an elephant from trampling you. --71.119.131.184 (talk) 05:48, 21 January 2016 (UTC)


 * Another possibility is the risk of injury to the animal. ←Baseball Bugs What's up, Doc? carrots→ 11:45, 21 January 2016 (UTC)


 * There are dog attack suits or bite suits you can find on web search, and of course the shark suit. Wnt (talk) 12:13, 21 January 2016 (UTC)


 * Have to agree it doesn't seem that such suits will be particularly useful in the scenario that was outlined, or really any likely scenario in a zoo. As also mentioned, it's unlikely something falling in to the cage would be considered urgent in most cases. If for example there is risk to human life like a baby or child that's dropped in to the cage, or perhaps a live weapon; an attempt would be made to draw the animal in to the secure area, meanwhile people with tranquiliser guns and live weapons will go on standby to shoot the animal if necessary and can be carried out without risk to human life. (The area around the cage is likely to be cleared as much as possible.) If it's fairly urgent, e.g. something that's fairly poisonous, most likely an attempt will made to draw the animal to the secure area. Perhaps tranquiliser teams will be put on standby. If it isn't something that really matters e.g. someone's digital camera, then it'll probably simply be left there and removed later, perhaps when the cage is normally cleaned. During routine cleaning, animal/s are drawn and locked into (or perhaps they already are in) a seperate enclosure if necessary   . Often I believe they are feed at the same time which makes it easier to draw them in to the seperate enclosure (if needed) and also distracts them during the cleaning. Multiple gates may be used to try and prevent accidents . The people involved should hopefully also have experience and training on how to deal with such animals.  I guess routine use of the suit may provide some emergency advantage if all the measures fail an animal does end up in the same enclosure. But the reduction in mobility and visibility combined with the extra weight and heat and unclear protection means it's probably not particularly useful compared to other methods to reduce the risk of harm. And there would also likely be other issues, like the difficulty & cost of cleaning such suits.  Tranquilisers are only used in genuine emergencies or when an animal needs to be inspected up close or operated on, and other methods  won't do. They aren't used just because someone happens to drop something in to the cage, nor against people in gorilla suits .  All the examples above seem to be either where you want the animal to bite you (dog training suits); where you want to be able to get very close for entertainment or study or other purposes and lack the ability to enforce separation (the bear suit and shark suit). In fact, consider the shark suit example, shark proof cages are used when you intentionally want to get close to a shark.  Nil Einne (talk) 14:40, 21 January 2016 (UTC)


 * Surprisingly, zoos have thought about how to manage animals and their enclosure. Larger animals likely to be dangerous to the staff will be housed in accomodation that has at least two seperate, lockable areas. This allows for those areas to be cleaned or maintained in whatever way in the physical absence of the animals. The other common reason that staff may want to get close to larger dangerous animals is for physical examination or treatment. Apart from the reasons given above about lack of mobility and practicality no amount of armour or physical protection is going to allow any animal keeper(s) to subdue a warthog let alone a chimpanzee or gorilla to the point where physical examination or treatment is possible. For some curious reason large primates, large cats, and the like just won't calm down however many keepers in armour or bite proof clothes hold them down. Some animals will surprise you though. Richard Avery (talk) 15:00, 21 January 2016 (UTC)


 * They do use armour when it is appropriate. E.g. Snake handlers use snake proof boots, and heavy gloves like these . Beekeepers also wear full protective suits. I think you also might be underestimating how many different ways that zookeepers can control their animals. If something valuable got dropped into the tiger pit, they'd not tranquilize the tigers, they'd probably feed them in another enclosure then close the door. If you want to learn more about actual best practices, many zoos have "behind the scenes" tours, and of course many documentaries show how zookeepers manage their flocks. Here's a clip from the Detroit zoo . If you want to learn more about armour, that's known as personal protective equipment in professional contexts, so searching things like /[zoo, animal of interest] PPE/ will show you some selection of what is used. Just searching /animal ppe/ got me the NIH guidelines, which require bite-proof gloves for some situations, but not all We also have a whole article on United_States_environmental_and_occupational_health_in_zoos.  SemanticMantis (talk) 15:07, 21 January 2016 (UTC)


 * Many large animals (e.g. elephants, rhinos) in zoos require daily inspection and perhaps daily treatment during illness. This is often achieved with positive reinforcement training.  The animals are trained to approach an area of their enclosure which is designed for "protected contact" and is almost always "behind the scenes".  The animal can be called with voice commands, and so can be summoned if, e.g. something is dropped in the enclosure.   This contact area is reinforced with a heavy steel structure which allows the animal to place limbs or areas of the body in such a way they can be examined closely or treated by humans.  So, it is a suit of armour of kinds, but it is immobile and not worn. DrChrissy (talk) 17:33, 21 January 2016 (UTC)
 * Thanks, "protected contact" is a very good key term. Here's a bunch of photos showing exactly what you describe . SemanticMantis (talk) 17:41, 21 January 2016 (UTC)
 * Some great examples there - thanks for those - as usual, a picture speaks a thousand words. DrChrissy (talk) 17:49, 21 January 2016 (UTC)

Lost mathematics and Scientific discoveries
I heard a lot of Scientific and Mathematical data and knowledge are being lost at an unprecedented rate, both online and in print format. How can we retrieve lost Scientific and Mathematics knowledge? — Preceding unsigned comment added by 100.38.74.62 (talk) 13:55, 21 January 2016 (UTC)


 * Where have you heard this? Jstor has far more articles online than they did 10 years ago, and they are continually adding more articles from further back in time and more obscure journals. The Royal Society put a huge chunk of their archive (starting from 1665) online and publicly accessible, only in 2011 . SemanticMantis (talk) 15:15, 21 January 2016 (UTC)


 * I guess you'll need to show us where you got this claim from...probably the original source for the claim could illuminate your question somewhat.


 * That said, the data behind an article in a scientific journal might maybe be destroyed, or at least be inaccessible somehow. I suppose that might be what they are referring to.


 * But if something is "lost" (in the sense of being "misplaced"), rather than being "destroyed" - then maybe all that's needed is better search technology?


 * Either way - please tell us where you heard this - maybe we can come up with a more concise answer. SteveBaker (talk) 15:32, 21 January 2016 (UTC)


 * The OP may be referring to data rot and should check out the much more comprehensive digital preservation. Not that the data was scientific, but I just threw out about 200 video tape recordings made in the 80's and 90's which have become physically unplayable or distorted to the point of uselessness.  I did take the precaution of backing most of them up to DVD over a decade ago.  My cassette tape collection is entirely useless. μηδείς (talk) 17:30, 21 January 2016 (UTC)


 * Our various links from curation may also be of use. The OP may be thinking of the increasing trend (or at least, increasing public perception) of libraries and other institutions throwing out large sections of their collections to make space. We don't have an article about the topic in particular (that I can see anyway), but there are tons of links out there, mostly either by people who just found out about the practice and are having an apoplectic attack or by the staff who have been discreetly doing it for years trying to talk people off the ledge. Here's a good example. Matt Deres (talk) 20:20, 21 January 2016 (UTC)


 * Weeding (library). DMacks (talk) 20:37, 21 January 2016 (UTC)


 * I think it is a known fact in Informatics that the science grows on its skin, in other words only the most recent articles are referenced in current publications. Most old publications are getting forgotten but I believe it is a normal process because in some way the correct knowledge is being preserved. Also I doubt this concerns Mathematics, only Medicine and Natural Sciences. --AboutFace 22 (talk) 23:53, 21 January 2016 (UTC)


 * There are cases where knowledge in individuals is lost, but a record still exists of that knowledge somewhere. One example is knowing how to use a slide rule. StuRat (talk) 07:52, 22 January 2016 (UTC)


 * I guess the point is that scientists and mathematicians don't have a particular responsibility to also be archivists and historians - so the loss of data that is no longer needed to conclusively prove things that are already well known and understood may not be of huge concern to them. In general, if some old piece of theory is at risk of being overthrown, someone will go and re-do the experiments it was based upon with more modern methods and equipment as a double-check. SteveBaker (talk) 17:40, 22 January 2016 (UTC)

Could STIs that are tolerable in one human population be deadly in another?
In other words, is there a human population that has been isolated from the rest of the world and may have no immunity or tolerance towards a certain STI, but then somehow intermarriage between the isolated human population and another human population occurs which may cause the formerly isolated population to be susceptible to disease? 140.254.136.149 (talk) 18:12, 21 January 2016 (UTC)


 * This is part of the history of syphilis. --TammyMoet (talk) 18:46, 21 January 2016 (UTC)


 * I see that syphilis is not from biblical times as I previously thought. I am not sure where I have heard this, but a long time ago, I heard that syphilis and gonorrhea came from biblical times. Now in retrospect, I think "in biblical times" really means "a long time ago". 140.254.136.149 (talk) 19:28, 21 January 2016 (UTC)


 * History of syphilis is more in-depth. The complementary article would be yaws. Matt Deres (talk) 20:24, 21 January 2016 (UTC)

Force of gravity at the center
[I understand that Newtonian gravity, while superseded by relativistic theory, is still accurate for general purposes. Please correct me if my understanding be wrong.]

Newton observed that the force of gravity is inversely related to the object's distance from the center of gravity; if I'm 1,000,000 km away from a body, I experience far less gravitational force (as far as it's concerned) than I do if I'm 1,000 km away from it. But what if you're 0.1km from the center? Since the denominator for the inverse-square law calculation is 0.25km, you should experience immense gravitational force (you're quadrupling the product of the masses, rather than dividing it as normal), but at the same time, since you're at the center of gravity, you're being pulled essentially equally in all directions, so you should experience essentially no gravitational force. Both can't be right; I've mangled something somewhere.

Furthermore, imagine that you're climbing an indefinitely strong ladder to Earth's center (geothermal heat ignored, so you can go all the way down without melting yourself), with indefinite strength and time — you can go either up or down, stopping whenever you wish without your weight breaking the rungs, so that you can feel your weight instead of falling and therefore being weightless. At what point, or in what area, will you weigh the most? Nyttend backup (talk) 20:25, 21 January 2016 (UTC)


 * The net gravitational force inside a uniform spherical shell is zero. This is a result derived by Gauss a long time ago. That means that once you are under the surface of a planet the material above you has no gravitational effect, so in the F=G*m1*m2/r^2, m1 is reducing. as r reduces. i'll leave you to do the (trivial) maths. Greglocock (talk) 21:06, 21 January 2016 (UTC)
 * [ec] A unique property of the inverse square law is that, inside a sphere, the gravitational attraction from the mass of the exterior of the sphere cancels out, so the gravitational force is the same as on the surface of an isolated sphere - in your example, a sphere of 0.25 km in radius. It's an interesting metaphysical point (or, at least, an element of the weak anthropic principle) that, given three-dimensional space, the universe only works if gravity follows an inverse-square law.  For the second question, the gravitational force varies linearly with the distance.  From Newton's equation $$F = \frac{GmM}{r^2}$$, M, the effective mass of the planet, is proportional to the cube of the distance $$(M = kr^3)$$, so the equation becomes $$F = \frac{Gmk r^3}{r^2}$$, or $$F = Gmkr$$ . Tevildo (talk) 21:15, 21 January 2016 (UTC)


 * You may be interested in the shell theorem. Basically, the "force of gravity is inversely related to...distance from the center of gravity" is only valid if the source of gravity is spherically symmetrical, and you are measuring the force from outside the sphere. The moment you enter a sphere (like the Earth), you can't use the same simplified equation anymore (Gmm/r2). The shell theorem explains why, as well as what happens when you enter the sphere. In fact, the gravity drops off to zero as you approach the center. Gravity would only approach infinite strength if the source of the gravity was compressed into a single point, as in a gravitational singularity, as this would be the only way to get arbitrarily close to the source of gravity without entering it. Someguy1221 (talk) 21:30, 21 January 2016 (UTC)
 * Indeed. To supplement the shell theorem article, we also have an article on Gauss's law for gravity.  Nimur (talk) 21:49, 21 January 2016 (UTC)