Wikipedia:Reference desk/Archives/Science/2018 March 15

= March 15 =

What weapon (or tool) is in this picture?
In the image in, what is this guy holding in his hand? If this is a gun, shouldn't he put it in a safer position? Like muzzle pointing down or up? --Doroletho (talk) 02:59, 15 March 2018 (UTC)
 * Knitting needles  Eve rgr een Fir  (talk) 03:04, 15 March 2018 (UTC)


 * I assume you mean on his lap. Cause if you definitely meant in his hand, what Evergreen said :). It's a short-barreled assault rifle with a foregrip, flashlight, optics, bipod and stock attached. Not sure what model it is, but the strange thing about this gun to me is that there's no obvious place to put a magazine, especially with the bolt looking like it's right above the trigger. So then the obvious place for the magazine would be inside the pistol grip, which would suggest this is a pistol-calibre assault rifle. Looking at such guns online, it resembles an MPA30DMG. Hopefully, he has the safety on and/or the gun is unloaded, though for safety you should do both of those, and have the barrel pointed in a safe direction. Someguy1221 (talk) 06:01, 15 March 2018 (UTC)


 * My guess is that it's one of the IWI ACE family (also looks like an Israeli soldier to me). Alansplodge (talk) 08:54, 15 March 2018 (UTC)
 * But those don't have a bullpup configuration. After a quick check I would suggest he has something like the IWI Tavor X95. Rmvandijk (talk) 13:26, 15 March 2018 (UTC)
 * Agreed. Alansplodge (talk) 22:18, 15 March 2018 (UTC)
 * There are many potential ways to make this situation appear safer, but I do wonder what the cultural / professional expectation is here. If other members of his unit saw this photo, would they criticize him for not having the barrel pointed in a safer direction (e.g. towards the floor)?  Or would they simply assume the weapon is unloaded and not worry about the way it is positioned?  Such judgments are often shaped by both written guidelines and cultural expectations.  Dragons flight (talk) 10:13, 15 March 2018 (UTC)
 * Its shurely a X95 in some configuration. Israeli forces are in a civil war for 30-40 years now? We can assume they know what they are doing when handling weapons. You can be harmed by a car as well and statistically it looks as if weapons are saver than cars, given everyone carries or drives them around in countries like Israel or the United States. The only point is, what some people in the United States keep missing, that not everyone is fit to drive a car or carry firearms. That is where the danger is. Not in laying your machinegun in your lap or driving your kids to school in your car, when you have learned how to handle that savely. --Kharon (talk) 14:03, 15 March 2018 (UTC)
 * Of course many Americans are born into places where it's so inconvenient to do anything without a car that getting a license and passing car inspection is made easy. Perhaps to partially compensate speed limits also tend to be slower than much of Europe (112.65kph might be the most common by population). Sagittarian Milky Way (talk) 02:45, 16 March 2018 (UTC)
 * There are speed limits everywhere in Europe aswell. Only the famous Autobahn 8D in Germany is an exception. Also everyone easily getting a license, to drive a car or own a firearm, may not be the main problem as long as there are enough checks to make sure the unfit loose theirs fast. --Kharon (talk) 05:41, 16 March 2018 (UTC)
 * SMW didn't say there were no speed limits. EU rather than Europe but [//ec.europa.eu/transport/road_safety/specialist/knowledge/speed/speed_limits/current_speed_limit_policies_en] says So if it's true motorway speed limits in the US are often only 112.65 km/h, this does seem lower than common in the EU. I'm not sure if their claim is accurate though as Speed limits in the United States by jurisdiction says  Admittedly the map shows the most populous Western state by far is excluded from this 'common' thing so maybe the population bit makes it true. Nil Einne (talk) 07:10, 16 March 2018 (UTC)
 * There's an inverse correlation of population density with speed limit in the US.
 * A thing the Wikipedia map doesn't usually show is urban Interstates (translation: E-road/4+ lane Australian National Route)are often slower than rural and not all stretches of rural Interstate have the highest limit of its state (many suburban miles count as urban). If this is common in Europe too that wouldn't be a difference though of course. For a few years after the national speed limit ended 104.6/88.5kph rural/urban motorway was I believe much more common but advances in car tech had encouraged states to raise them (with some holdouts i.e. New York State). From 1974 to 1987 it was 88.5kph nationwide but that was only because the federal oil conservation law was stricter then (yet the raising it to 104.6 on rural motorways was vehemently opposed by the National Safety Council, Public Citizen, Mothers Against Drunk Driving and the Insurance Institute for Highway Safety) Sagittarian Milky Way (talk) 20:28, 16 March 2018 (UTC)
 * I think this has a lot more to do with lobbies like those you pointed out forming "high-speed" and "low-speed" camps and disabusing politicians of any courage to change the status quo than anything else. Personally, I have not noticed any correlation in national speed limits and general road quality in Europe, although a common factor among most places is that the enforcement is more lax than in the US. 93.136.119.107 (talk) 00:25, 17 March 2018 (UTC)
 * "On the best estimate, about an eighth of the whole [Autobahn] network of 13,000km (8,000 miles) has no speed limit and about a third has a permanent limit, with the bit between coming and going according to need".  Alansplodge (talk) 15:55, 16 March 2018 (UTC)

Threshhold value of stimulus for triggering ejaculation
How can the intensity of stimulus necessary for triggering ejaculation be expressed in some physical-physiological units and what is its threshhold intensity or numerical value?--82.137.15.144 (talk) 23:58, 15 March 2018 (UTC)
 * For some research on this topic, see here, here and here . SemanticMantis (talk) 01:46, 16 March 2018 (UTC)
 * Some things are better measured by qualitative research than by metrics. Klbrain (talk) 00:15, 18 March 2018 (UTC)
 * "When you can measure what you are speaking about, and express it in numbers, you know something about it." Lord Kelvin. Dmcq (talk) 09:26, 18 March 2018 (UTC)