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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 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 / 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 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 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

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)

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 ${\displaystyle F={\frac {GmM}{r^{2}}}}$, M, the effective mass of the planet, is proportional to the cube of the distance ${\displaystyle (M=kr^{3})}$, so the equation becomes ${\displaystyle F={\frac {Gmkr^{3}}{r^{2}}}}$, or ${\displaystyle F=Gmkr}$ . 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/r). 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)

January 22

gravitons

how do they whizz here there asnd everywhere at infinite speed to convey the force of gravity between all objects in the universe?--178.105.166.117 (talk) 01:25, 22 January 2016 (UTC)

The graviton is a hypothetical particle (not discovered yet), which is supposed to travel at the speed of light. Tgeorgescu (talk) 01:41, 22 January 2016 (UTC)

One thought experiment which I still find fascinating is that given light takes about 8 minutes to travel from the sun to the earth; IF somehow it was possible for the sun to just instantly wink out of existence, we would not have any way of knowing this had happened for 8 minutes. The sun would still be visible in the sky and the earth would keep orbiting around the now non existent sun for another 8 minutes. After that 8 minutes, we would "see" the sun disappear, and instead of following it's previously curved orbit, the earth would start to travel in a straight line the direction it was last traveling as the sun vanished. That is to say, Gravitons do not have infinite speed. Vespine (talk) 02:37, 22 January 2016 (UTC)

The thing is, no two points in spacetime can interact faster than c, so to an observer on Earth the Sun only stops existing when they see it go bye-bye. There's no way the observer could "know" the Sun stopped existing while the Sun's light is still getting to them. --71.119.131.184 (talk) 21:51, 22 January 2016 (UTC)

We actually have an article on the Speed of gravity. There is no direct measurement of the speed of gravity, though this may be possible in the future with measurement of gravitational waves. The indirect measurements that have been attempted show a speed consistent with the theory that changes in gravitational fields (and perhaps gravitons themselves) propagate at exactly the speed of light. Someguy1221 (talk) 04:06, 22 January 2016 (UTC)

If things worked any other way, there would be severe causality issues that I strongly suspect would be obvious at the galactic level. SteveBaker (talk) 04:33, 22 January 2016 (UTC)

(Strictly speaking, I don't think anything would be egregiously broken if gravity propagated slower than the speed of light—not that there's any reason to suspect such a thing.) TenOfAllTrades(talk) 19:28, 23 January 2016 (UTC)

If space is literally bent near massive objects, then the explosion of one of those objects should alter space in some kind of "ripple effect" in its gravity - extending, as hypothesized, at the speed of light. Unfortunately for us, our ability to witness the sun going nova would be very short-lived. And the earth wouldn't head off in a straight line, as the massive amount of debris from the explosion would, at the very least, start pushing us away from the sun's former location. Or more likely it would incinerate and disintegrate the earth, which would become part of the debris from the sun. On the plus side, this is not likely to happen any time soon. ←Baseball Bugs carrots→ 15:22, 22 January 2016 (UTC)

Just a note, in my hypothetical situation, it's not enough for the sun to go nova for the gravity to disappear. In a nova only a small fraction of the mass is "used up" and the mass, whether whole or "exploded" would have the same gravity. Of course the energy of the explosion would blast everything "outwards", but disregarding that the earth would still orbit the nova, it wouldn't start traveling in a straight line. Vespine (talk) 22:41, 24 January 2016 (UTC)

Parachute jump

Suppose you are dropping paratroopers into a fairly small DZ on a windy day (but without wind shear); if you know the drop altitude AGL and the wind speed, can you calculate how far upwind of the DZ should you drop the paratroopers so they will land near the center of the DZ with a minimum of steering? 2601:646:8E01:9089:F4FA:EFCF:C9DF:C509 (talk) 02:45, 22 January 2016 (UTC)

I'm certain you can. The military would no doubt take that into consideration when deploying paratroops. Pretty much all modern parachutes are steerable, so it might not be much more than if it's light wind, deploy a bit up wind from the DZ, if there's more wind, deploy a bit further. Do that a few times and you'll quickly get the hang of how far away you have to deploy for a particular wind speed for a particular parachute. Vespine (talk) 03:05, 22 January 2016 (UTC)

Here is how the U.S. Army does it. Shock Brigade Harvester Boris (talk) 03:06, 22 January 2016 (UTC)

Thanks! So if the wind is blowing at 15 knots and you jump from 1000 feet, you'll drift about 450 meters, right? 2601:646:8E01:9089:F4FA:EFCF:C9DF:C509 (talk) 08:17, 22 January 2016 (UTC)

It's not quite that simple:

1) Wind speed, and even direction, varies with altitude. So, you'd need to account for the drift at each level.

2) You are assuming sustained winds, but there are also wind gusts to deal with, which are, by their nature, unpredictable.

3) How far they are blown off course depends on their rate of descent. Therefore, wind will have minimal effect until the parachute is opened.

4) There's also a problem in heavy winds that once they land they could be dragged by the wind. (There is a parachute release mechanism, but using that while being dragged over rough terrain might be difficult. If they could release the instant they hit, then they would be OK, although the released parachutes blowing across the field will give away their position.) StuRat (talk) 08:29, 22 January 2016 (UTC)

Yes, you did calculate the drift D=KAV correctly using a personnel Load Drift Constant K = 3.0 meters per paragraph 6-32 and figure 6-4. But you also need to take the forward throw into account, as discussed in paragraph 6-36 and table 6-9, which is given as 229 meters for personnel out of a C-5, C-130, or C-17, and then you need to combine them vectorially with regard to wind direction and drop heading as discussed in section 6-89 and shown in Figure 6-8. There seems to be a problem with that figure in the PDF linked above by Shock Brigade Harvester Boris, so you may prefer this copy of the complete US Army Field Manual FM 3-21.38, Pathfinder Operations (with chapter 6, Drop Zones).

Note that there does seem to be an error in that manual in the "Determination of Release Point Location" section (starting with paragraph 6-89). Figure 6-8 shows all five steps, but Step 5 is omitted in the discussion, and the example given under the discussion of Step 4 (paragraph 6-93) belongs under the missing discussion of Step 5 as it is the calculation of Throw Distance, which for rotary-wing and STOL aircraft "equals half the aircraft speed (KIAS), expressed in meters." -- ToE 16:09, 23 January 2016 (UTC)

So, for a DC-3 flying at 100 knots, the paratroopers would be thrown forward 50 meters? 2601:646:8E01:9089:94DA:2520:D95F:848D (talk) 02:45, 24 January 2016 (UTC)

It's probably greater than that. Clearly the "equals half the aircraft speed (KIAS), expressed in meters" formula for rotary-wing and STOL aircraft does not extend to the higher drop speeds of the fixed wing aircraft in table 6-9 with forward throws of 229 meters, as there is no way that they have drop speeds anywhere near 458 knots. In fact, table E-1 gives a personnel drop speed of 130 - 135 knots. The formula breaks down somewhere, and I suspect that it is a stretch to apply at the 90 knots used in the example problem. If I had to guess, based purely on intuition, I'd be tempted to scale it with the square of the drop speed, and predict (100/135)^2 * 229 m = 125 m. -- ToE 04:36, 24 January 2016 (UTC)

It's worth noting that they very often drop supplies and weapons alongside the paratroops - and steerable parachutes don't help those things! So there is a degree of importance to making the drop in the right location. SteveBaker (talk) 17:37, 22 January 2016 (UTC)

N-A=S what these letters stand for?

In chemistry there is a formula for finding the number of the bonds. N-A=S what these letters stand for? 92.249.70.153 (talk) 14:06, 22 January 2016 (UTC)

S= N-A, where S is the total number of shared electrons, N is the total number of valence shell electrons needed by all the atoms in the molecule or ion to achieve noble gas configurations and A is the total number of electrons available in the valence shells of all the atoms in the structure. — Preceding unsigned comment added by 81.131.178.47 (talk) 15:32, 22 January 2016 (UTC)

A link to show the context. Mikenorton (talk) 15:35, 22 January 2016 (UTC)

Spanish electric connector

Hi, does anyone know whether this old type of connector found in Spain has an official name or not?

Thanks in advance.--Carnby (talk) 19:13, 22 January 2016 (UTC)

Tough call. This looks like a very WP:RS. It has official names and specification codes for many, many, plugs/sockets. It simply calls this type "old spanish socket". It doesn't have a picture, but the description matches these photos very well, IMO. oops; sorry :( SemanticMantis (talk) 19:56, 22 January 2016 (UTC)

That's a mirror of an old version of AC power plugs and sockets. -- Finlay McWalterᚠTalk 20:01, 22 January 2016 (UTC)

D'oh! Thanks, I will look more carefully at the header next time :) SemanticMantis (talk) 20:05, 22 January 2016 (UTC)

Maybe you can ask our Spanish friends over at Misplaced Pages:Café/Archivo/Técnica/Actual or elsewhere on la enciclopedia libre. The Quixotic Potato (talk) 00:52, 23 January 2016 (UTC)

 Done--Carnby (talk) 12:33, 23 January 2016 (UTC)

Top British medical Schools?

Can someone give a simple, easily copied list of the most prestigious British medical schools? This inquiry is for a user who has very limited WP access, and who Wants me to send a list (category), rather than a full-blown prose article. Thanks. ````` — Preceding unsigned comment added by Medeis (talk • contribs) 21:23, 22 January 2016 (UTC)

Googling "British medical schools" gives me this. Rojomoke (talk) 22:56, 22 January 2016 (UTC)

Adding "top" to the search gives me this ranked list. Rojomoke (talk) 23:00, 22 January 2016 (UTC)

List of medical schools in the United Kingdom is the wikipedia article for this. There are only 32 medical schools in the UK. So, there is no problem taking a look at all of them. I'm not sure what part of them are top. The Guardian score linked above could be slightly misleading. All of them seem to get scores that are not far apart.--Llaanngg (talk) 18:13, 23 January 2016 (UTC)

@Medeis: - (Position: I've done quite a bit of education consultancy work and advice with private tuition and out-of-school education) - All British medical schools essentially teach the same syllabus with the same entry criteria, so there’s a limit to how different they can be. Furthermore, by not attending a London university or Oxbridge you probably get reduced cost of living, so attending a ‘worse’ university may have dramatic compensations.
Honestly, your friend probably wants to worry about getting the grades to be in a position to make that choice. From tuition work I've done I've been startled to see kids in year 10 (age 15) predicted BCC science GCSEs whose parents say they need help deciding whether they should become a doctor or a dentist. 94.119.64.1 (talk) 16:56, 24 January 2016 (UTC)

Thanks, I'll pass that on. What's actually going on (and the reason I didn't just google it, although I did send the results above) is not an actual choice of schools, but backstory for a story set in Britain. Had I been asked the same question for the US I would have suggested the University of Pennsylvania, which is top-tier, but not a cliche like Harvard or Columbia. But as an American I have no knowledge of British schools other than the obvious cliches. μηδείς (talk) 17:39, 24 January 2016 (UTC)

"Prestige" doesn't really have the same meaning WRT British academia as the Ivy League etc does in the US, other than a tendency for Oxbridge to consider themselves superior (sometimes with and sometimes without justification). Since most institutions in England and Wales (Scotland and NI are independent for the purposes of education) are charging the legal maximum tuition fee of £9000 per annum, there's a strong levelling effect since if a place starts getting a bad reputation, people will just go elsewhere. If you want a place with all the rowing-and-rugger English cliches, but avoiding Oxbridge, I'd suggest Barts. ‑ Iridescent 18:01, 24 January 2016 (UTC)

My friend agrees Barts would have been ideal, if not for Sherlock Holmes, and has settled on UCL, and I have sent the text of that article and some images. Thanks, again, for the assistance. μηδείς (talk) 20:07, 24 January 2016 (UTC)

January 23

Developmental stage of cells and freezing

Why does freezing work when we freeze egg cells, embryos, or sperm, but does not work for higher level of development? By work I mean you can still thaw (defrost?) it and get a functional human out of it? --Scicurious (talk) 01:36, 23 January 2016 (UTC)

Probably someone else will provide more details but our article Cryopreservation and to a lesser extent Cryobiology and Cryonics has some details. Note that your idea freezing just works is largely incorrect. For both Embryo cryopreservation and Oocyte cryopreservation, you have to carry out an effective method of cryopresevation or you're most likely not going to have much success. Notably as our article says, human oocyte cryopreservation is still a relatively new technique. (As embryo cryopreservation is older, some women have frozen embryos which were fertilised by a former partner, which can lead to problems if the partner does not wish the embryos to be used.) Even Semen cryopreservation generally uses some method although the large number of sperm in a normal sample means you have a larger margin for error. Nil Einne (talk) 04:15, 23 January 2016 (UTC)

Yes, I mean "freezing an egg cell works" (somehow works, by proper procedure). I.e. it's possible. This is contrary to "freezing a baby", which never works, no matter what you do. I.e. you won't be able to reactivate it. --Scicurious (talk) 13:51, 23 January 2016 (UTC)

for your final statement. AFAIK, and this is supported by the articles I linked to, there's no intrinsic reason based on our current understanding to think it's impossible although it is likely to be very difficult. The reasons why it's so much more difficult with a whole organism where you have to successfully freeze and revive the vast majority of cells in a complex large (in all dimensions) system are given in the article, although many of the, should be obvious with a bit of understanding of ow cryopreservation techniques work and biology and physics. And you already see similar issues when comparing sperm vs oocytes or embryos. Nil Einne (talk) 14:32, 23 January 2016 (UTC)

BTW, my comments and questions have a definite purpose. They are important because if you have a fundamental misunderstanding of what is and isn't possible and how it is and isn't possible; this may very well be one of the reasons why you're having trouble understanding why whole organism cryopreservation for organisms with large & complex body structures like humans (or even Drosophila ) is very difficult. And it's not like it hasn't been achieved for adult organisms with simpler body structures like various nematodes . P.S. I don't intend to suggest complexity and size are the only factors although they are big ones. For a variety of reasons certain things may actually be easier to cryopreserve than you would expect comparing to something else. Also I don't think cryopreservation of vertebrates is an active area of research and definitely not dogs or cats or even rats. But cryopreservation of organs is to some extent . This shouldn't be that surprising, if you can't even really cryopreserve a rat heart yet, cryopreserving a whole rat is very unlikely. Nil Einne (talk) 15:42, 23 January 2016 (UTC)

The problem isn't related (trivially) to stage of development, but to size and complexity. We can readily freeze and thaw many types of mature human cells. What we can't (usually) do is freeze large pieces of animal tissue. That is to say, we can freeze, store, and revive primary cardiomyocytes, but not hearts; we can freeze, store, and revive primary hepatocytes, but not livers; and so forth. TenOfAllTrades(talk) 18:41, 23 January 2016 (UTC)

Why we stop producing lactase as adults?

I have read about being lactase persistent is an advantage for survival. Only 10% of the world population are lactase persistent as adults. The 10% that are lactase persistent are results of a mutation occurred thousands of years ago. We are all born with lactase persistent as babies then lose it as adults. My question is why do we lose it as adults? If that was an advantage, why natural selection turned it off during adulthood? Why most people were not lactose persistent until mutation kicked in? All the answers to this question "why" I found online include something like because we don't need milk as adults anymore. Yes, sure, while we don't need milk as much as we do as babies, but it is still considered to be an advantage. Just because we don't need something doesn't mean that thing doesn't have an advantage. That doesn't answer why the gene is turned off in adulthood. Why natural selection was not at work until much later when some new mutations kicked in? Thank you! (p.s.: I don't care about the mechanisms and any other matters; the answers should focus only on the why aspect). 146.151.96.202 (talk) 06:37, 23 January 2016 (UTC)

Because producing lactase uses energy, which takes energy away from other stuff? That's the best answer I can give you. 2601:646:8E01:9089:90DA:8B23:BEB4:5241 (talk) 07:55, 23 January 2016 (UTC)

As is explained in our article Lactase persistence, it was not an advantage in societies that didn't have dairy farming so it was turned of in adulthood. it was only turned back on in societies that had developed dairy farming. Richerman (talk) 11:23, 23 January 2016 (UTC)

Okay, even if it wasn't an advantage in societies that didn't have dairy farming, but it was not an disadvantage either. Why was there the need to turn the gene off as adults? 146.151.96.202 (talk) 21:04, 23 January 2016 (UTC)

Infant mammals have only one oral activity which is suck-swallow-breathe and this represent a drain on maternal resources until they develop the skills of eating and swallowing solids. Mammals have various way of encouraging infant skill development as soon as possible, which is an evolutionary advantage in the wild. Lactose intolerance i.e. cessation of Lactase production that causes the infant animal to experience stomach upset if it persists in breast feeding, contributes to the infant seeking independent nutrition.

Are you saying the gene was turned off in adulthood is the natural selection way of encouraging infant independence of its mother? If lactose persistent population can be independent without the gene turned off, this argument doesn't seem to hold. The gene does not need to be turned off for the babies to seek independence. The mother can teach the babies to be independent. I see no harm in keeping the gene on. Why it was turned off in the first place is puzzling me. 146.151.96.202 (talk) 21:02, 23 January 2016 (UTC)

No. Contribute to means help to cause or bring about (Oxford Advanced Learner's Dictionary). It attacks a Strawman to say this argues the cessation of Lactase production is "the essential natural selection way". Do you also need to be given a justification for each developmental change from infant to adult such as loss of Umbilical cord, loss of primary teeth, and loss of Moro reflex? AllBestFaith (talk) 01:57, 24 January 2016 (UTC)

I thought the usual idea was that, if older children kept nursing, they would compete with their younger siblings, to the disadvantage of the latter.

Of course the mother could prevent that. But would she? The same question applies to the "independence" version, actually. It's not absurd that there might turn out to have been an evolutionary advantage in making the weaning more automatic. --Trovatore (talk) 21:36, 23 January 2016 (UTC)

Trovatore. "The same question applies to the "independence" version." Can you explain more what do you mean by this statement? And why wouldn't the mother prevent that? It makes sense that the mother would make the older siblings seek independence, so that she could feed the younger ones with her milk (since the young ones are unable to eat solid food yet). It's entirely possible to become independent without turning off the gene as happened with cultures that are lactose persistent. Again, I see no clear advantage in turning off this gene.146.151.96.202 (talk) 20:21, 24 January 2016 (UTC)

Some human populations have developed Lactase persistence, in which lactase production continues into adulthood. It may have developed as a response to growing benefits of digesting the milk of farm animals such as cattle. Research reveals lactose intolerance in humans to be more common globally than lactase persistence and the variation has been tied to genetics, but that the largest source of variation has been shown to be based on exposure (e.g., cultures that consume dairy). P.S. Sensible consideration of evolutionary factors should identify probable mechanisms without which answers to "why" are only speculation.

See the article sections about Lactase persistence#Evolutionary advantages and Baby-led weaning in humans. AllBestFaith (talk) 14:00, 23 January 2016 (UTC)

I don't know where there is something about this but I think I also read somewhere there is an advantage in stopping the transmission of diseases in having children be appreciably different from adults in various ways, so there is a drive to accentuate differences. Dmcq (talk) 15:21, 23 January 2016 (UTC)

Video and scientific racism

Video in question. Most scientific racism came from whites during the age of scientific racism, but this particular video has it coming from a black man. I know evolution is not a ladder and lifeforms don't become "better" or "degenerate" as they mutate, they merely adapt to the environment, but I was curious if anyone had any direct refutations of what this man is saying. ScienceApe (talk) 17:00, 23 January 2016 (UTC)

There are plenty of easily found analyses of scientific racism. You appear to be asking this question just to show us that a black man can be a "scientific" racist too. --Llaanngg (talk) 18:15, 23 January 2016 (UTC)

(edit conflict) In the unlikely event that this is a genuine question and not a piece of trolling, there's an explanation of this particular theory and the arguments around it at Melanin theory. ‑ Iridescent 18:55, 23 January 2016 (UTC)

What points do you want us to refute? There's no scientific racism involved in the video, the guy is a racist talking garbage with almost no science involved. He claims that white people are a different species to black people and then a few seconds later says that they are the same species. His claims that white people are more prone to depression and violence isn't supported by any research (obviously there are some studies that would support that claim, while other studies would show that black people are more prone to depression and violence). I'm not sure what the 'SAR' gene is that he mentions, but if white people were that prone to a genetic problem it would be common knowledge, not posted by an idiot on youtube 95.146.213.176 (talk) 00:13, 24 January 2016 (UTC)

As I said above, this is not really a question, but a means to spread the word about this deluded black racist. --Llaanngg (talk) 02:05, 24 January 2016 (UTC)

You really think I was trying to spread the word about this guy? I can assure you I wasn't. I was hoping for a direct refutation of the things he was saying. If I was trying to spread his word, I think twitter or facebook would be a better venue don't you think? ScienceApe (talk) 17:26, 24 January 2016 (UTC)

I know people are having a knee jerk reaction to this video which is understandable. I agree, he is an idiot, I was hoping for a refutation of the points he was saying though. He didn't say white people are a different species, he said they are the same species. As for the points I want you to refute, he mentions "SARA" makes white people more violent. Do white people possess this gene at a higher level as he alleges and what does it do? He also alleges that slc2485 gives them pale skin and alleges that it was developed in central asia. At 1:15 he mentions something but I can't make out what he's saying, but he alleges that it gives them straight hair. He goes on to say that 3%-4% of white DNA is from neanderthals. He alleges that they are able to cope with cold weather from the creatine in their skin. He then says at the "demi level" that 4% stretches out to 70% of their skin. These are some of the allegations he's making. Like I said, I'm not saying he's being rational nor am I defending what he's saying. I just want to know if the assertions he's stating are correct or not. ScienceApe (talk) 17:35, 24 January 2016 (UTC)

While I didn't catch the part where he called them a seperate species (he did say something about some people feel they are "something different" and it's cool and people should feel like that), I largely stopped listening when he mentioned demi level. Since "demi level" is not even close to a scientific concept, it's not surprising if the rest of his talk is similarly unscientific. Nil Einne (talk) 00:48, 25 January 2016 (UTC)

I don't even know what demi level means. ScienceApe (talk) 02:22, 25 January 2016 (UTC)

Um isn't that precisely the point? We don't know because it isn't a scientific concept and this is a science desk. If random people are talking random crap in videos where one of their basic points refers to non scientific concepts, then there's little point analysing their videos to find if any of it has any scientific merit in any of what they say. If you don't have sufficient knowledge to dismiss demi level offhand, a simple search will show it's not a scientific term. It's possible that it's simply an incorrect name for a common concept (which considering the person talking clearly speaks good English even using their personal cultural variant is a warning sign in itself); but if there's uncertainty over whether demi level is actually referring to any scientific concept but by the wrong name, it makes sense to ask about that rather than getting in to nitty gritty over whether claimed gene frequencies are correct (let alone whether these genes have any well established link to violence). 09:00, 25 January 2016 (UTC)Nil Einne (talk)

Why does powdercoated metal, like the inside walls of a microwave, not spark?

75.75.42.89 (talk) 23:40, 23 January 2016 (UTC)

Small amounts of metal won't spark. ScienceApe (talk) 23:44, 23 January 2016 (UTC)

Small amounts of metal certainly will spark - have you never put a cup or plate with a gold leaf rim in a microwave? Whether a piece of metal arcs or not depends on it's shape - thin edges or points tend to build up a charge and arc (spark). The side walls are flat with no edges so the microwaves are reflected back and don't build up a charge. Other metal components, such as the metal rack, are designed without points or sharp edges for the same reason. Richerman (talk) 00:54, 24 January 2016 (UTC)

(ec) A metal object in the cavity of a microwave oven can produce sparks if it concentrates the electric field sufficiently to cause breakdown of the air. Whether this is the case depends on the size, shape, position and orientation of the object. A metal object with sharp edges is likely to concentrate the field at the edges, particularly if the size of the object is such that the electric currents on it resonate at the frequency of the applied field (~2.45 GHz). The walls of the cavity do not give rise to sparks because they lack extremities with convex edges, rather than because they coated. --catslash (talk) 01:18, 24 January 2016 (UTC)

Additionally, the fact that the cavity of a microwave oven is made of metal is essential to its operation. The walls of the oven form a Faraday cage, trapping the microwaves inside the oven. If your microwave has a window, you might have noticed the metal grating over it. This is also part of the Faraday cage. The openings in the grate are smaller than the wavelength of microwaves, so microwaves cannot pass through them. Visible light has a much shorter wavelength, so it passes through just fine. --71.119.131.184 (talk) 01:55, 24 January 2016 (UTC)

I think ScienceApe meant small in size. Each granule of the powdercoat metal is insulated from the next granule, so there is no large voltage induced. The gold leaf rim will not spark if it is cut into small sections. Dbfirs 09:15, 24 January 2016 (UTC)

Small amounts are fine. ScienceApe (talk) 16:56, 24 January 2016 (UTC)

Thanks. So you're all saying a smooth steel ball bearing with no small bumps or surface defects could be microwaved without sparking? 75.75.42.89 (talk) 22:06, 24 January 2016 (UTC)

January 24

"freeform" electromagnetic coils

1. What's the proper name for these "freeform" electromagnetic coils?

2. How are they made? Roughly which one of the following guesses is the closest?

A) wind one layer, spray some adhesives, and then wind another layer on top

B) Adhesives are added continuously as the winding continues

C) The magnet wire is pre-coated with an adhesive.731Butai (talk) 04:36, 24 January 2016 (UTC)

If there were a coilform with a central cylindrical core and endpieces, the coil could be wound as shown by rotating the coilform while the supply bobbin moved slowly back and forth via gearing to lay down straight layers. The endpieces could then be removed and the wound coil pushed off the central cylinder. The wire would tend to maintain its form, but clearly it would deform if stressed. It could be dipped in varnish to cement it together into a rigid form. Edison (talk) 05:05, 24 January 2016 (UTC)

Is the one that you uploaded yourself or that you have information about? It is not obvious from the picture alone that this is intended to be an electromagnetic coil as it has no terminals, no adhesive can be seen and the wire could be uninsulated (not magnet wire). A spool of plain wire delivered from a factory could look like this. AllBestFaith (talk) 16:15, 24 January 2016 (UTC)

Analogue live TV

Before digital "film", how was live television done? My mental image of television, pre-digital, was that the scene was recorded by a videocamera and microphone, the sounds modulated onto electromagnetic waves as with radio, the film developed and then the images somehow modulated onto electromagnetic waves, and chronological conjunction between the two processes is enforced to ensure that the video and sound be synchronised. This doesn't seem to fit with live TV, however, as there's no time to develop anything; how would it be possible to broadcast anything that wasn't a recording? Today, it's easy: you can basically use the same techniques as Skype, but that wasn't possible in the 1950s. Nyttend (talk) 05:40, 24 January 2016 (UTC)

Television cameras before the 1980s used video camera tubes. Basically they worked like a CRT television in reverse. In a CRT display, one or more tubes scan their beams across the screen to produce the picture. In tube cameras, the camera focuses incoming light onto a target and one or more tubes scan the target. --71.119.131.184 (talk) 05:50, 24 January 2016 (UTC)

Note also that for quite a long time, a lot of prerecorded stuff on TV was direct on to Videotape not film. In fact, sometimes the content may have gone from videotape to film.

And BTW home camcorders weren't that uncommon before everything went digital. America's Funniest Home Videos for example was before digital video was particularly common, and some Youtube videos also look they were probably recorded on analog tape.

Nil Einne (talk) 07:07, 24 January 2016 (UTC)

Let's put it this way. You (Nyttend) have the mental image "that the scene was recorded by a videocamera". But that's really two things: converting the scene into an electronic signal, and recording the electronic signal. In a live breoadcast, the electronic signal would be used directly (more or less) to modulate electromagnetic waves just as the audio signal is used in radio. (For live color TV it would also be necessary to convert the R/G/B signals from the camera into the applicable encoding, i.e. NTSC, PAL, or SECAM.) --76.69.45.64 (talk) 07:22, 24 January 2016 (UTC)

Incidentally, the processes Nyttend describes is John Logie Baird's "Intermediate Film Technique", used for a few months in 1937 in the UK, but obsolete since then. It introduced a delay of about 1 minute in a live broadcast - see this article. Tevildo (talk) 09:03, 24 January 2016 (UTC)

Germany transmitted film-intermediate TV earlier. During the 1936 Summer Olympics experiments were conducted with both an analog electronic camera and with a mobile TV truck. On the roof of the truck was a film camera. The film was developed in the truck and then run through the transmitting apparatus. AllBestFaith (talk) 17:09, 24 January 2016 (UTC)

Live TV originally went "straight to air", with no intermediate recording and playback steps. The signals from the microphones and camera were combined (usually through vision mixer and audio mixer desks) into a composite signal which was distributed to the transmitter site, modulated onto an RF carrier, and broadcast. All of these were real-time analog processes, with no delay except for that inherent in signal processing and propagation. The Anome (talk) 10:09, 24 January 2016 (UTC)

The Anome has hit on it. Just like a phone call, there is no need for a TV camera and transmitter system to make a permanent record of anything: if you have an outside broadcast unit you can just turn on a camera, transmit that signal to a control centre and then put it out on the air, without at any stage 'recording' it permanently. Much early TV was broadcast live without any copy of it being kept. Before the days of cheap magnetic recording systems, if you needed a permanent record of it, you'd often literally just film a television set with a film camera. Similarly, most analogue phone calls have never (one assumes) been permanently recorded onto anything. They just go from one phone to another through the wires. Blythwood (talk) 13:02, 24 January 2016 (UTC)

Thanks to everyone! I had no idea that it was possible for the TV camera to do anything except impress each scene on a separate film still; I didn't know that they used CRTs to send imagery to a transmitter. I'd imagined that the first cameras of any sort that used neither film or U-matic videotape were digital cameras. Nyttend (talk) 15:26, 24 January 2016 (UTC)

U-Matic was really quite a late development. There's a lengthy history of different types of analog video format, starting, I believe, with two-inch quad, and I believe digital videotape made its first commercially successful appearance with the advent of D-1 recording. -- The Anome (talk) 23:58, 24 January 2016 (UTC)

I'm fairly confused why the OP is conflating video tape and film. The distinction here is IMO important because while it's easy think a camera which is exposing light on to film would not be able to modulate an EM signal, if your camera is already modulating a signal onto video tape it's harder not to see the possibility of bypassing the video tape step completely. Of course when you think about it more, even with film, you have to modulate the signal somehow. If you are doing this by shining light through the processed film and then using the resulting image to modulate a signal, why can't you just skip the step of going from light to film to light?

In any case, note that beyond broadcast TV, it wasn't that uncommon for CCTV systems to be display only, which was I believe the initial form of CCTV per our article.

Nil Einne (talk) 00:32, 25 January 2016 (UTC)

See also Kinescope. ←Baseball Bugs carrots→ 15:19, 24 January 2016 (UTC)

The modern equipment for conversion from movie film to electronic TV signal (for taping or immediate transmission) is a Telecine. AllBestFaith (talk) 17:21, 24 January 2016 (UTC)

@Nyttend: - as a related point, early video recording on magnetic tape was so expensive that often even when TV was recorded down onto tape or a film, the tapes were soon wiped over and reused - often tony TV executives seem really to have thought that this junk they were producing was surely of no lasting interest to anybody. The result is that much TV made as late as the mid-1970s, even in prosperous and stable countries and even by public service broadcasters with a high image of themselves, was erased. So yes, a lot of early TV was sent through the TV broadcast system like a phone call, with no recording device of any kind set up to make a record of it for posterity. Blythwood (talk) 10:52, 25 January 2016 (UTC)

Considering starting a new project on here

Hello all! As a spare time project, I’m looking to do spend some time in the next few months messing around with R, its graphics packages in particular. I’d be interested in combining this with my contributions to Misplaced Pages (do two obsessions together!) - does anyone have suggestions for any publicly available molecular biosciences data that might be interesting to do something with? Preferably something I can't screw up too badly! Blythwood (talk) 11:43, 24 January 2016 (UTC)

A while back I got to messing with Module:ImportProtein, which is in Lua (see the talk page for an example), and like so many things... put it aside for "a while". If you're interested, I'm not reserving the copyright. :) I wasn't aware of any direct R integration with Misplaced Pages, though it would create interesting possibilities! Wnt (talk) 14:25, 24 January 2016 (UTC)

Some aspects of it might be too close to original research, which is fine for other places, but not welcome in wikipedia. On the other hand, you could research numerical data already on Misplaced Pages and plot it in a more visual way. --Scicurious (talk) 15:40, 24 January 2016 (UTC)

Did the universe start with only neutrons?

If hydrogen fusion created all other atoms from hydrogen, and hydrogen is a proton and an electron, and fission reaction is the decay of a neutron into a proton and electron, then did the universe start with only neutrons? — Preceding unsigned comment added by 86.153.69.165 (talk • contribs)

Our current theories imply that there were subatomic particles before neutrons existed; and it seems like neutrons and protons both started emerging roughly around the same time. Have a read through Chronology of the universe, Quark–gluon plasma, and related articles.

I think your insight is good, in that you're looking for reverse- reactions (like beta decay) and trying to conserve charge; but you are missing some important complications that arise when we study sub-nuclear particles in great detail. We now know that there are lots of valid ways that we can break protons and neutrons apart if we use very high energies. Present theories for the early universe imply that our heavy particles were created around the hadron epoch after protons and neutrons coalesced from quarks. Before that time, the energy density was so high that we barely understand the rules that govern quark combination: what we do know is that there were no protons or neutrons yet.

Nimur (talk) 15:13, 24 January 2016 (UTC)

Reverse polarity Schottky diode

On Digikey in the diode section, what does the "schottky, reverse polarity" diode type stand for? I understand what a regular Schottky diode is, but am not sure what a reverse polarity Schottky diode is. Johnson&Johnson&Son (talk) 15:05, 24 January 2016 (UTC)

Could it be a Schottky diode for creating a reverse polarity protection?--Scicurious (talk) 15:47, 24 January 2016 (UTC)

The OP has linked to a diode selection guide where one chooses filter(s) to limit the selection. Applying the "Schottky Reverse Polarity" filter reduces the number of manufacturers (to 2) and introduces selection menus for reverse leakage and capacitance when reverse biased. They are all Schottky diodes and this is just the guide designer's way to offer a detailed reverse specification if needed. AllBestFaith (talk) 16:42, 24 January 2016 (UTC)

Why do they make pipes out of lead?

^Topic ScienceApe (talk) 16:59, 24 January 2016 (UTC)

"Lead piping was used because of its unique ability to resist pinhole leaks, while being soft enough to form into shapes that deliver water most efficiently." ScienceApe, you constantly asking questions where the answer is the first Google hit on the question is starting to pass over the line separating "good faith curiosity" from "trolling". ‑ Iridescent 17:05, 24 January 2016 (UTC)

I don't appreciate being accused of trolling. If I wanted to troll, I would ask a bunch of nonsensical questions using multiple sock puppet accounts so you didn't know they were from the same person. ScienceApe (talk) 17:19, 24 January 2016 (UTC)

Maybe you are doing it, but was not caught yet. Anyway, it's difficult to see a purpose on your questions sometimes. Maybe you should perform a simple search for a question before you ask it here. Otherwise you would look more like a science ape, than as a science curious person. --Scicurious (talk) 17:50, 24 January 2016 (UTC)

I don't need to prove I'm not a troll, but you're free to believe whatever you like, however I'm not going to stop asking questions if I'm curious about something. However feel free not to respond to my questions. ScienceApe (talk) 20:41, 24 January 2016 (UTC)

Of course you don't need to prove anything. However, if you are disruptive on wikipedia including the RD by continually asking pointless questions, you should expect to be restricted. Even if you don't reach that level, you should expect to be ignored, even when you ask okay questions if you continue to ask pointless questions. Nil Einne (talk) 00:15, 25 January 2016 (UTC)

Ok well then you can report me and try to get me blocked, but your threats are not going to dissuade me from asking questions. ScienceApe (talk) 02:19, 25 January 2016 (UTC)

A real life reference librarian who frequently scolded patrons for not just looking stuff up themselves would soon be fired. If it makes someone that angry when someone asks a question that is easy to find an answer for, then the angry librarian should find other areas of Misplaced Pages in which to work. It is disruptive to scold people who ask question when it is not clear they are trolling, as it is not clear here.Edison (talk) 20:49, 24 January 2016 (UTC)

Thanks I appreciate that. If nothing else, this should have been kept to talk pages and off the reference desk. ScienceApe (talk) 02:19, 25 January 2016 (UTC)

We should compare with some of the alternatives available at the time:

1) Iron pipes: These can rust. While a small amount of added iron in the diet may actually be healthy, in antiquity people didn't know that iron pipes were healthier than lead. Also, the orange or brown water it produces doesn't look or taste good. And eventually the pipes can rust through. (There are water treatment methods to prevent rust, but they wouldn't have had those in antiquity, either.)

2) Ceramic pipes: These can crack, due to seismic activity, frost-freeze cycle, tree roots, or subsiding of the ground around it. Therefore, they tend to be leaky.

3) Copper pipes: These can corrode to produce green sludge and eventually fail from that corrosion. Similar to iron, a bit of added copper in the diet may actually be healthy, but they didn't know that in antiquity.

So, if you didn't know about lead poisoning, lead pipes seemed like a good option (or gold pipes, if you happened to be filthy rich). StuRat (talk) 17:39, 24 January 2016 (UTC)

Wooden water pipes were popular in London for mains water supply in the 16th to 18th centuries, but generally connected to lead pipes in peoples' houses. I believe that they were still being replaced in the 1960s. IIRC they were generally made from Elm wood which is resistant to rot when not exposed to air. Alansplodge (talk) 18:02, 24 January 2016 (UTC)

Yes, I forgot about wood. Bamboo can be used, too, since it's naturally hollow, although some type of sealant may be need at the joints. StuRat (talk) 18:51, 24 January 2016 (UTC)

My gut feeling is that this would have to do with metal prices - alas that article, unfortunately, doesn't contain even a current table, let alone historical data. It would be worth updating with information from various sites like this. But my impression is that lead is a cheap metal because it is not usable for very many things, and a pipe buried in the ground is one case where the weight and the softness don't count against it. Alas, even that didn't pan out in the end... Wnt (talk) 20:38, 24 January 2016 (UTC)

Lead is usable for a lot of things. If only it wasn't poisonous. --71.119.131.184 (talk) 23:51, 24 January 2016 (UTC)

Coefficient of friction between nickel and polyethylene

Where can I find the coefficient of friction between nickel and polyethylene? Actually the coefficient of friction between nickel and any common plastic would be fine.

I found this site that has the data for nickel and Teflon, but Teflon is little too difficult for me to get my hands on. Johnson&Johnson&Son (talk) 17:10, 24 January 2016 (UTC)

The coefficient of friction of plastics is usually measured against polished steel. PTFE (Polytetrafluoroethylene, brand name Teflon)'s coefficient of friction is 0.05 to 0.10. Polyethylene can be supplied in various grades for which this supplier quotes coefficients of friction 0.18 to 0.22. That is for steel. This table gives some comparison with nickel. AllBestFaith (talk) 17:55, 24 January 2016 (UTC)

Thanks. But the problem is I don't have a steel part; I have a part that's coated in nickel. Is there a way to derive or approximate the nickel-plastic CoF given the steel-plastic CoF? The engineershandbook.com link you gave has nickel-glass, nickel-nickel, and nickel-steel CoF listed, but unfortunately it doesn't have any for nickel-plastic. Johnson&Johnson&Son (talk) 02:40, 25 January 2016 (UTC)

Look for firearms information. Nickel coated bolt carriers and nickel-teflon triggers are common. --DHeyward (talk) 05:14, 25 January 2016 (UTC)

January 25

Why do Northeast Megalopolis snowstorm records look like this instead of a northern bias?

Boston: 27.6 inches (2003)

New York: 26.9 inches (2006) (27.9" (2016) if the site became the nearest airport in the mid-20th century like the others)

Philly: 31.0 inches (1996)

Baltimore: 29.2 inches (2016) (Baltimore suggests this might just be the record since the airport existed (1950))

Washington: 28.0 inches (1922)

Washington Dulles Intl, Virginia: 32.4 inches (2010) despite this weather station only starting in the 1960s.

Does the distribution of water vapor by latitude have anything to do with it?

How sure are scientists that climate change will make single snowstorm records easier to break in the future? Sagittarian Milky Way (talk) 00:15, 25 January 2016 (UTC)

Let me speak to the relationship between how far north (or south, in the Southern hemisphere) you are and the amount of snow you get. The closer to the poles, the lower the temperatures. At low temperatures, less moisture evaporates from lakes, rivers, and oceans, especially once they freeze over. This makes for less snowfall. Therefore, there is very little snow at the South Pole, but, since it rarely melts, you see thousands of years worth of snowfall on the ground at once.

Now, this doesn't necessarily affect the snowfall amounts in this particular storm, as many other factors and local conditions are also more important, but it is a general trend. In fact, many of the places with the heaviest snowfalls historically are places which get lake effect snow, where air moves over warm water, picking up water vapor, then depostits it once it moves over colder land. Buffalo, New York is one such spot, with Lake Erie providing the (relatively) warm water. StuRat (talk) 00:49, 25 January 2016 (UTC)

Locations move. Equipment and methods change. And the forecast has uncertainty . There is no reason to believe any of it is related to climate change as climate change has still remained unmeasurable as an observation of weather. --DHeyward (talk) 05:54, 25 January 2016 (UTC)

Stupid physics question

According to wikipedia, the age of the universe is 13.8 billion years. The origin of the universe was a single point which resulted in a big bang. The size of the universe is 91 billion light years. Nothing can go faster than the speed of light. In 13.8 billion years the size of the universe should be 13.8 light years right? Brian Everlasting (talk) 00:34, 25 January 2016 (UTC)

It's actually a very common question. The answer is that the space between large-scale structures in the universe expanded by a process called Inflation (cosmology). Dbfirs 00:38, 25 January 2016 (UTC)

This is wrong. The boundary of the visible universe is only affected by expansion since the CMBR last scattering time, around 380,000 years after the big bang. It is unrelated to inflation, which ended 10 seconds after the big bang. -- BenRG (talk) 01:41, 25 January 2016 (UTC)

Yes, of course! Light didn't start out until after inflation stopped, so it is entirely Metric expansion of space (and that is speeding up). Dbfirs 09:56, 25 January 2016 (UTC)

(EC)see Cosmic Inflation. The part that makes it super confusing is that you would be correct IF the universe actually "big banged" INTO pre-existing space, but it didn't, SPACE it self formed along with the big bang. Vespine (talk) 00:40, 25 January 2016 (UTC)

There's also the complication of Metric expansion of space but this is minor by comparison. Dbfirs 00:44, 25 January 2016 (UTC)

The key point is that relativity says nothing can travel faster than the speed of light (in a vacuum) through spacetime. It says nothing about how quickly spacetime itself can move. This distinction is crucial for understanding things like inflation, but such nuance tends to be omitted from pop science descriptions, which tend to say almost-true-but-subtly-misleading things like "nothing can travel faster than light". --71.119.131.184 (talk) 00:55, 25 January 2016 (UTC)

Also in that vein, the size of the observable universe is 91 billion light-years. The size of the universe as a whole may be infinite: see shape of the universe. --71.119.131.184 (talk) 00:57, 25 January 2016 (UTC)

Someone deleted my time dilation and Theory of Relativity comment, but I don't see any changes in the View History tab. Willminator (talk) 01:08, 25 January 2016 (UTC)

What I was trying to say in my deleted comment is that time is relative according to the Theory of Relativity. Gravity affects time. For example, if someone were to approach a black hole, from the observer on Earth looking up, it would look like the person has slowed down for thousands of years, but from the person's point of view, only seconds would have passed. The light of a star that's let's say, 1000 light years away from Earth doesn't necessarily have to travel 1000 years to Earth from the perspective of an observer on Earth. Willminator (talk) 01:24, 25 January 2016 (UTC)

The image on the right shows how this works geometrically. Later times are at the top. The brown line (on the left) is Earth, the yellow line (on the right) is a distant quasar, the diagonal red line is the path of light from the quasar to Earth, and the orange line is the distance to the quasar now. You can verify by counting grid lines (which represent 1 billion (light) years each) that the quasar is 28 billion light years away along the orange line though the light took only about 13 billion light years to reach us. -- BenRG (talk) 01:49, 25 January 2016 (UTC)

Liquid non-Newtonian fluids?

Which non-Newtonian fluid or fluids would be considered only a liquid, not a plastic solid nor a colloid that involves liquid mixed with solid particles unless there's a colloid that is considered to be only a liquid, nothing in between? I have learned that not all fluids are liquids, but that all liquids are fluids. A couple of examples of non-Newtonian fluids are toothpaste, ice in the case of moving glaciers, ketchup, lava, pitch, and much more. They don't flow easily and consistently like water and other Newtonian liquids do. I read that pitch is said to be the world's densest liquid, but it is also considered to be a viscoelastic, solid polymer. What does that mean? Is it always a liquid? Can one look at the molecular structure of non-Newtonians fluids to determine which ones are truly liquids? Willminator (talk) 01:05, 25 January 2016 (UTC)

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