Wikipedia:Reference desk/Archives/Science/2016 June 18

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June 18

What Species Does This Spider Belong To?

https://imgur.com/oGzhWmM I took this photo of that spider and later I tried to catch it. It bit me and didn't let go so I started to shake my hand very fast then it fell off. I wanna know if it's poisonous or not. The location is South India, if that helps. Thank you very much. — Preceding unsigned comment added by 96.47.231.219 (talk) 01:08, 18 June 2016 (UTC)

See your doctor. ←Baseball Bugs ^{What's up, Doc?} carrots→ 03:52, 18 June 2016 (UTC)

I am not a bug specialist but it looks a lot like an albino "flower crab spider" from the Family Thomisidae, possibly Species Thomisus or less likely Species Misumena (also see pictures of Thomisus and Misumena). IF this is one those its venom is very toxic to bees but not so much to humans, still ANY spider bite can be dangerous if it becomes infected so seek medical treatment to be safe. Koala Tea Of Mercy (KTOM's Articulations & Invigilations) 05:16, 18 June 2016 (UTC)

It is a crab spider, it's not an albino, it's just white. And I really don't think it's appropriate to tell OP to seek a doctor - we shouldn't give that kind of advice, especially since the OP just asked for ID. SemanticMantis (talk) 16:17, 18 June 2016 (UTC)

Thank you, I'm really happy to find out which species it is. I will go to doctor. 96.47.231.219 (talk) 07:53, 18 June 2016 (UTC)

Be sure to take the photo with you. ←Baseball Bugs ^{What's up, Doc?} carrots→ 08:20, 18 June 2016 (UTC)

Going to see a doctor because a random internet person told you to seems silly to me. I hope OP doesn't spend a lot of money to be told they are fine. "Most spider bites are harmless, and require no specific treatment." even for dangerous species like recluses (which this is not) "In almost all cases, recluse bites are self-limited and typically heal without any medical intervention.", per spider bite, with reference. This is not medical advice, it is information about spider bites in general. IMO, telling OP they should seek medical treatment is not our purview. SemanticMantis (talk) 16:17, 18 June 2016 (UTC)

Not as silly as trusting advice from random internet users. ←Baseball Bugs ^{What's up, Doc?} carrots→ 17:19, 18 June 2016 (UTC)

I agree, but I have given no advice. SemanticMantis (talk) 18:00, 20 June 2016 (UTC)

I should have said, "IF YOU'RE CONCERNED, then see your doctor." But since you're asking about it, you at least "seem" to be concerned. ←Baseball Bugs ^{What's up, Doc?} carrots→ 17:45, 18 June 2016 (UTC)

Oh, and technically what spiders and some snakes have is called venom. ←Baseball Bugs ^{What's up, Doc?} carrots→ 17:47, 18 June 2016 (UTC)

Plumbing

What is the water pressure in a typical municipal water supply? 67.164.54.236 (talk) 04:24, 18 June 2016 (UTC)

According to Water supply#Water pressure: "Typical UK pressures are 4–5 bar (60-70 PSI) for an urban supply.[citation needed]. However, some people can get over eight bars or below one bar. A single iron main pipe may cross a deep valley, it will have the same nominal pressure, however each consumer will get a bit more or less because of the hydrostatic pressure (about 1 bar/10 m height). So people at the bottom of a 100-foot (30 m) hill will get about 3 bars more than those at the top."--Shantavira|^{feed me} 06:28, 18 June 2016 (UTC)

Thanks! And in the USA? 67.164.54.236 (talk) 06:39, 18 June 2016 (UTC)

To take as an example, San Jose, California, in home water pressures are between 50 and 60 PSI, but the actual pressure in the main can be as high as 150psi [1]. Again, PSI at the point of entry to a home will vary with altitude relative to the water supply, plus or minus half a PSI per foot. Someguy1221 (talk) 11:18, 18 June 2016 (UTC)

BTW, 50 psi equals about 3.5 bar. Alansplodge (talk) 19:29, 18 June 2016 (UTC)

Thanks, everyone! 67.164.54.236 (talk) 09:43, 19 June 2016 (UTC)

• There is a tendency in recent decades (UK at least) to reduce the high supply pressures. This is achieved as a result of replacing Victorian water towers and gravity systems from hilltop reservoirs with electric pumps, and more pumps distributed more evenly across the network. Although this first arose as a consequence of changing the delivery technology, it is also recognised as having benefits. High pressures are unpopular with householders, plumbers and water supply companies. They encourage leakage through valves, they increase leakage rates through pinholes in pipes and they can significantly affect water loss rates for a network. Energy costs are also a major cost for water supply, so pumping to a more consistent and lower system pressure requires less energy than pumping to a higher pressure at fewer locations.

Note that the US approach of water supply, where every small settlement has a small water tower, is almost unknown in the UK. Our water towers are rare, becoming rarer, and were always larger to each supply a greater area. Andy Dingley (talk) 10:01, 20 June 2016 (UTC)

They're not all that rare: I know because they're often a convenient structure on which to install mobile (cell) phone antenna, which my current company has the job of repairing when necessary. {The poster formerly known as 87.81.230.195} 185.74.232.130 (talk) 14:28, 20 June 2016 (UTC)

Not sure if I'm interpreting you correctly, but water towers are kind of old-fashioned in the U.S. as well. Some older communities still have them, but here in Southern California they're almost non-existent. Also a lot of rural areas get water from wells rather than towers. --71.110.8.102 (talk) 02:28, 21 June 2016 (UTC)

how to solve this plane

Question deleted as it is a duplicate of question placed on Maths desk. -- SGBailey (talk) 09:37, 18 June 2016 (UTC)

Ohio River tributaries: discharge at mouth

Other than minor streams, the Beaver River is the first river that flows into the Ohio River after the latter's origin in Pittsburgh. I'm trying to discover which river is the next biggest downstream: in other words, once you pass the Beaver going downstream, what's the first river you reach that's bigger than the Beaver? I found USGS data for a few rivers (Beaver, data a few miles above the mouth, where it's similar to the mouth, Muskingum, again just a little above the mouth, and Kanawha, at the mouth), but they seem quite different from each other: it seems that the Beaver discharges 21,807 cubic feet per second, versus 17,662 for the other two put together, and having seen all three river mouths several times, I can't imagine how the Beaver is bigger than both of the others. Each of the three USGS pages is quite different from the other two, so perhaps they're not presenting quite the same data, or maybe I'm misunderstanding something. Can someone help me find a page, whether USGS or somewhere else, that would give statistics for these and other Ohio River tributaries in a single table or other single-page format, so I could be confident that the same kinds of information are being provided for each one? Nyttend (talk) 15:21, 18 June 2016 (UTC)

The water flow carried by a river is, obviously, proportional to its width times its average depth times the speed of the current. When you talk about looking at the mouth of the different rivers, can you really tell how deep they are or how fast the water is flowing? --69.159.60.83 (talk) 06:34, 20 June 2016 (UTC)

River icebreakers

Right at the mouth of the Kanawha River (see previous question), the USGS quads have marked three different spots as "Ice Breaker". Go to 38°49′46″N 82°7′34″W, pick ACME Mapper, and select Topo mode (options at top right) to view the quads. One is upstream and two downstream: immediately north of the "R" at the end of "River", just south of the terminus of the PIPELINE, and south of the second one on the other side of the river.

In this context, what is an ice breaker? Does someone (USGS? US Coast Guard? State of West Virginia?) put devices into the river that serve to retard the presence of river ice? Even if they were using an icebreaker ship here, there wouldn't be any reason to mark locations on topographical maps. Nyttend (talk) 15:31, 18 June 2016 (UTC)

An interesting question. I have only just started searching Nyttend but I did find this mention of ice piers. It might not be relevant but it also could give additional info to add for those that research your question. MarnetteD|Talk 15:39, 18 June 2016 (UTC)

There is a bunch of info and maps here. I have to go run some errands so I didn't get a chance to see if ice breakers get a mention later on. MarnetteD|Talk 15:50, 18 June 2016 (UTC)

I should think a triangular "blade/plow" pointing into the direction of presumed ice flow would tend to break it up. Of course, it would soon refreeze, perhaps explaining why they need several on a river. StuRat (talk) 05:20, 19 June 2016 (UTC)

Nyttend, did you notice the structures, presumably ice breaking piers, visible in satellite imagery at the location of the southernmost of your three charted Ice Breakers? Here. Similar structures are not visible corresponding to the two Ice Breakers on the right bank. -- ToE 11:51, 19 June 2016 (UTC) The Kanawha is flowing NW toward its confluence with the Ohio, so that makes it two upstream and one downstream of your mark.

Social skills

Are social skills something you can lose if you don't use it just like other skills? 2A02:C7D:B954:1900:EC02:EA7C:166A:896F (talk) 17:25, 18 June 2016 (UTC)

Only in very very rare and extreme cases (some people go insane without any human interaction). (((The Quixotic Potato))) (talk) 18:41, 18 June 2016 (UTC)

This is such a broad question to ask. Have a look at Personal space which relates to e.g. that uncomfortable feeling when someone is too close to us in a queue. This varies from country to country. I can imagine someone moving from one country to another and gradually learning a different personal space and then perhaps "losing" this social skill of the previous country. Might be helpful for the OP to be a bit more specific on the social skill they are thinking of. DrChrissy ^(talk) 19:03, 18 June 2016 (UTC)

I once advised a Frenchman that the reason we Americans of both sexes kept backing away from him was that he, a Parisien, kept approaching us too closely. (We'd been warned of this malheur in junior-year French class.) He became extremely upset, saying this was an "accusation of homosexuality" (he was openly gay, which didn't help), and broke out in tears. My clique, about 10 boys and girls, all hugged him, or at least shook his hand, said we were not gay (except myself, but not interested) and he was very comforted and comfortably distant thereafter. μηδείς (talk) 02:10, 19 June 2016 (UTC)

The most studied cause of extreme isolation from other individuals is solitary confinement, and it has dramatic negative effects on future social interactions. However, this is not strictly the same as simply not exercising social skills, as solitary confinement only occurs in a prison setting, so their are many other negative factors and correlates. The research certainly shows that piling social isolation on top of imprisonment is very bad for one's ability to get along with other people. Outside the prison setting it's hard to judge. Most people who voluntarily withdraw from social contact are already suffering from some illness, such as depression, which would make it hard to judge whether its the isolation or the depression that causes anything you might see. Someguy1221 (talk) 21:51, 18 June 2016 (UTC)

Purely anecdotally, accounts of people such as marooned sailors, lone frontiersmen and others, whose accidental or vocational situations result in a solitary existence for an extended period, often mention their temporary difficulties in social relations and conversation when they first re-encounter other people.

Any skill which is improved by practice must surely also be subject to deterioration if unpracticed for a long period. Our Social skills article includes the text:

"Individuals with few opportunities to socialize with others often struggle with social skills. This can often create a downward spiral for people with conditions like depression. Due to their depression, they avoid opportunities to socialize, which impairs their social skills, which makes socialization even more unattractive." [My italics.]

{The poster formerly known as 87.81.230.195} 5.66.223.127 (talk) 23:54, 18 June 2016 (UTC)

Are y'all talking about social skills eroding, or about social skills never developed? ←Baseball Bugs ^{What's up, Doc?} carrots→ 09:02, 19 June 2016 (UTC)

Per the OP's "something you can lose if you don't use it just like other skills", I think we all are talking about erosion rather than failure to develop. With reference to the latter, Feral Child would be relevant. {The poster formerly known as 87.81.230.195} 185.74.232.130 (talk) 14:32, 20 June 2016 (UTC)

The OP could tell us for sure. Unfortunately, it appears that the OP was just a drive-by. ←Baseball Bugs ^{What's up, Doc?} carrots→ 03:22, 21 June 2016 (UTC)

Many of the descriptions of Alexander Selkirk (especially of his time in Bristol) suggest that his social skills were poorly developed, and that's why he was marooned in the first place. Andy Dingley (talk) 23:27, 20 June 2016 (UTC)