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June 23

Naegleriasis cause of death

Is the ultimate cause of death in cases of naegleriasis damage from the pathogen itself, such as from necrosis or bleeding? Or is the cause of death related to inflammation of the brain? Does the human body mount a significant immune response to the parasite? Someguy1221 (talk) 04:42, 23 June 2016 (UTC)

From this paper [1]:

Basically, "yes". N. fowleri...deeply penetrates the cortex to the periventricular system, and incites meningoencephalitis with rapid cerebral edema, resulting in cerebellar herniation. The olfactory bulbs and orbitofrontal cortices are necrotic and haemorrhagic. Histology has shown acute inflammatory reaction, mainly composed by neutrophils with extensive areas of lytic necrosis with the presence of several trophozoites.... Increased intracranial pressure and herniation are usually the cause of death. Opabinia regalis (talk) 05:47, 23 June 2016 (UTC)

So yes, there is a significant immune response, and yes the cause of death is inflammation, not really the necrosis or direct impact of the pathogen. SemanticMantis (talk) 13:40, 23 June 2016 (UTC)

Well.... technically, according to that source, the increased ICP caused by the inflammation is the cause of death, not the inflammation itself. Nitpicking, I know, but it's a causal sequence, infection causes neuroinflammation, which causes oedema, which causes raised ICP, which causes death. The inflammation is only halfway through the process. Fgf10 (talk) 22:49, 23 June 2016 (UTC)

Fair enough. I think the important thing is that the causal chain is long. At some point, the amoeba is responsible as an ultimate cause, but it's not really "trying" to kill you, the way many/most other diseases are (please excuse the teleological shorthand and consequent scare quotes). SemanticMantis (talk) 16:21, 24 June 2016 (UTC)

I'll forgive the shorthand, but I'm unsure about the "many/most" comment. Surely almost every microbe simply "wants" to survive and multiply. Our deaths do almost nothing to help that, so my guess is that it would actually be quite rare for a microbe to intentionally bump us off. I'm no epidemiologist, but I can't think of a single one where our death would provide a benefit to them. Matt Deres (talk) 18:21, 25 June 2016 (UTC)

Necrosis itself also can cause edema, causing raised ICP...etc., though I don't know how much that contributes in this particular sequence of events. Opabinia regalis (talk) 23:08, 23 June 2016 (UTC)

Slow-moving water

What's the difference between a bayou and a slough, at least in its North American use? I understand that the former term is more common in the southern USA than elsewhere, but one can find bayous and sloughs together in the same areas farther north, and the definition in the latter article does a good job of defining places that are typically named "bayou", whether today or in 1820 (both links address the same location), as well as defining places such as Levy Slough at 37°51′5″N 88°0′19″W. I'm not clear if the terms are generally used as synonyms (e.g. "creek" and "brook") or if there's some distinction between them. Nyttend (talk) 14:36, 23 June 2016 (UTC)

Mostly synonymous, as per our articles and the dictionaries I just checked. My NOAD says bayou: (in the southern US) a marshy outlet of a lake or river. from Louisiana French, from Choctaw 'bayuk'. Slough:a swamp, a muddy side channel or inlet. That bayou definition is a bit narrower, and I prefer the broader sense given in our article (what does Oxford really know about Louisiana French anyway - though it does clarify that nobody really talks about bayous much outside of the southern USA)

There are perhaps some differences in denotation, but then we get into regionalisms and personal preferences. E.g. some people do think there's a difference between a brook and a creek (and a rivulet and a stream, etc.), but it's not really correct to say those are well-supported distinctions. Anyway, if you want subjective denotations: Bayous often have cypress knees, sloughs don't. Slough gets used sometimes for human-engineered backwaters/drainage things, bayou doesn't. Bayou is usually reserved for something rather larger, sloughs can be pretty small. SemanticMantis (talk) 17:45, 23 June 2016 (UTC)

Thanks for the checking. I've always lived in hillier areas nearer headwaters (the only river city in which I've lived sits half on a bluff and half on a narrow plain along a somewhat entrenched river), so I've only known either bayous or sloughs as a visiting outsider. I should have made it more clear that I was indeed looking for solid, well-agreed-upon distinctions, because indeed I wasn't interested in personal preferences or individual distinctions. Nyttend (talk) 18:54, 23 June 2016 (UTC)

I still can't find any authority attempting to carefully formalize a definition for either. This is the stuff of folk taxonomy, methinks. Anyway, neither word appears in this fairly comprehensive glossary of hydrology [2]. Neither word appears in our Glossary_of_geography_terms. They have brief and ever-so-slightly different definitions in this National Geographic glossary [3]. SemanticMantis (talk) 19:46, 23 June 2016 (UTC)

In England, a "slough" is only to be found in the pages of The Pilgrim's Progress (the "Slough of Despond"), unless you count Slough of course. Alansplodge (talk) 20:52, 23 June 2016 (UTC)

There is a nature reserve in Coventry called Wyken Slough though. --TammyMoet (talk) 11:23, 24 June 2016 (UTC)

English also has [4] slough n. an outer covering that can be shed such as the cast-off skin of a snake, and slough v. to cast off (hair, skin, horn or feathers), from 1720. AllBestFaith (talk) 21:19, 23 June 2016 (UTC)

According to our articles and to [5] a Bayou has slow moving or stagnant water and a slough is only sporadically filled with water[6]. What I find interesting is that in British English we don't use it as a noun in that sense any more, although, as Alansplodge says, we have the town of Slough - pronounced "slau". However in BE we have "plough" - which is now spelled "plow" in American English, but for some reason slough has kept its old spelling in AE. Incidentally, when the word is used as a verb in BE i.e. to "slough off", it is pronounced "sluff" like the word "clough" - which is a wooded valley in Northern England - or "enough". Complicated or what? According to the Oxford dictionary definition given above the difference in pronunciation is because the noun derives from middle english and the verb from low German. Richerman (talk) 23:30, 23 June 2016 (UTC)

"Slough" doens't rhyme with "plow" in American English so why should it be spelled the same. "Slough" rhymes with "slew". Rmhermen (talk) 18:15, 24 June 2016 (UTC)

As does "through". ←Baseball Bugs ^{What's up, Doc?} carrots→ 18:53, 24 June 2016 (UTC)

According to Merriam Webster it can be pronounced either slau or slew in AE - it probably depends where you come from. Richerman (talk) 19:13, 25 June 2016 (UTC)

I remember seeing a claim that American English is actually less altered from ancient usage than British English; presumably the dispersal of colonists and the relative paucity of culture slowed down linguistic innovation for a bit? But that's a topic for a different question... in any case, "slough" is specifically mentioned in the American English article, alas with 'citation needed' beside it. Wnt (talk) 23:43, 23 June 2016 (UTC)

This discussion has been closed. Please do not modify it.
The following discussion has been closed. Please do not modify it.
So does "slough" in AE not rhyme with "plow"? In Britain, if anyone talked of a caterpillar "sluffing" off its old skin they would be laughed out of the office. 92.23.53.54 (talk) 18:38, 25 June 2016 (UTC) Then I suggest you look at the pronunciation in wiktionary and the OED [7]. Richerman (talk) 19:17, 25 June 2016 (UTC) That one word "slough" comes from different roots with different meanings, which could help explain the different pronunciations.[8] ←Baseball Bugs What's up, Doc? carrots→ 18:42, 25 June 2016 (UTC) Er, yes, I think I explained that above. Richerman (talk) 19:13, 25 June 2016 (UTC)

Big Rip, black holes

If and when a big rip occurs, will black holes be ripped apart also?144.35.45.67 (talk) 19:33, 23 June 2016 (UTC)

They gradually lose mass due to accretion of phantom energy, see here for details. Count Iblis (talk) 20:38, 23 June 2016 (UTC)

The Big Rip hypothesis assumes that the Speed of gravity is finite such that in a continually accelerating expanding universe all matter eventually becomes unbound by gravity. There could then be no Event horizon boundary between the inside and outside of a Black hole. AllBestFaith (talk) 21:07, 23 June 2016 (UTC)

Fear of heights totally absent on a ship, why?

Being on the fifth story of an appartment building I feel less than perfect. However, being up much heigher on a cruiseship I feel totally comfortable. Looking down from a balcony: zero problem even when the ship is docked and I'm looking down at the dock. Why is that? Joepnl (talk) 20:56, 23 June 2016 (UTC)

Handrail. AllBestFaith (talk) 21:22, 23 June 2016 (UTC)

Nope Joepnl (talk) 21:26, 23 June 2016 (UTC)

Think this is simply different mental reference points of fearful situations. Unease in building is possibly an implicit memory formed years ago (with the original experience that formed it forgotten). Some people can't bring themselves to climb to the top of a three extension ladder but thoroughly enjoy their vocation jet leaving the runway. It is all to do with context. You may have become older-and-wiser by the time you first experienced a cruse ship and thus your implicit memory didn’t trigger due to the different context, which was not down to hight itself but the situation, but cruse ships were not part of the experience, when your naïve implicit memory formed. So, being on a cruse ship doesn’t trigger anything from the past. There is a technique called 'search back', where by think back to the time when the unease was first noticed – a re-examination of the event can nullify the unease. --Aspro (talk) 22:13, 23 June 2016 (UTC)

There's maritime law and the law of gravity, but no maritime law of gravity. So nothing to fear. InedibleHulk (talk) 22:59, June 23, 2016 (UTC)

A very interesting post. Anna Frodesiak (talk) 23:02, 23 June 2016 (UTC)

Seriously though, it might have to do with solid straight lines. If they converge, as in the side of a building against a street, that can give you a different perspective from the wavy, curvy lines. A bit easier to discern how far you'd fall, I find. InedibleHulk (talk) 23:05, June 23, 2016 (UTC)

Can you even see the side of a ship from a railing at all? If not, and you're ever close beside something your own height, try scanning to the bottom of that thing instead. I'll bet you'd feel at least a bit sweatier. InedibleHulk (talk) 23:37, June 23, 2016 (UTC)

I'm not so sure the OP wants tips on how to increase his anxiety level. :) ←Baseball Bugs ^{What's up, Doc?} carrots→ 00:06, 24 June 2016 (UTC)

I don't mind an experiment for science :)

@InedibleHulk Yes you can and still no problem. But you are right, I have no fear of heights at all in an airplane. It's also not that the ship is made of "safe" metal compared to "unsafe" bricks or concrete. The Eiffel Tower is terrible as well :) But thinking of a floating Eiffel Tower, I think I'd have no problem climbing it! It really is strange. Joepnl (talk) 00:34, 24 June 2016 (UTC)

Also strange is how pictures can have the same effect, despite the viewer knowing damn well they're perfectly safe. Spiderman 2 messes me up worse than any "more realistic" game I've seen since. And Turok: Dinosaur Hunter still makes me carsick, while cars don't. InedibleHulk (talk) 13:56, June 24, 2016 (UTC)

Pictures like that make my hands sweaty, knowing that not only the building is perfectly safe, but that I'm just looking at a picture of it as well :) Joepnl (talk) 13:52, 25 June 2016 (UTC)

I'm pleased that xxx is enquiring enough to asked this question, because the contradictions (in feelings) can appear baffling to one's own logical side of the brain. So, sure the the OP is looking for an answer -so would I in his situation if I didn't I know the answer already (don't all you jump on me together for RS proof - just pointing it out). One's own instincts are a wonderful thing. When one is young and can't intellectualize a potential danger, instincts are your friend -they protect you from harm. As young ones, we get bombarded from every-side, with advice from adults saying such things as don't stand too close to the edge, you may fall etc. Up a three-extension-ladder they might say be very careful. Again these comments reinforce unease. Yet, get onto a holiday jet that has to wait 20 minutes from push back to finally getting to take off and everyone on board is jubilant. They have paid good money to the airline who has (one hopes) employed and air crew that takes on the responsibility for ones safety. So, no trigger. One does not have to 'take care' of oneself as it is being done by others -the air crew. Note too. The OP mentions that if the Eiffel Tower was floating they would have no trouble. Is this not a bit like sky-divers who when early on exiting a planes feel great trepidation -like walking off a edge of a cliff... When they progress to doing free-fall at much higher altitudes, their minds become so focused on free-fall techniques that they can step out of the plane without using will-power to over come their initial instinctive fears. Think about it. Face it: One has to be completely nuts to exit an aircraft with just a main and secondary cute to prevent you from becoming strawberry jam when you hit the ground. But with experience, one over comes those instinctive fears. Lets take this to the extreme - for added emphasis. Bet the last thing on the astronauts mind that do EVA's on the ISS is getting splattered on a side-walk 200 hundred miles below. The context is so much different. I mention Reachback earlier and now you have the link. Do it and you will not only be able to look over the edge of the Eiffel Tower but come to the UK and experience the "Walk of Faith" and enjoy the experience. This is no more than just a glass floor on Blackpool Tower to stop one plummeting down to the side walk below. What is the difference between a concrete floor or a glass floor? (Imagination, that's all). Blackpool Tower Eye (Glass Floor Walk, Lift and Ballroom)--Aspro (talk) 15:01, 24 June 2016 (UTC)

A glass floor is also much more pleasant to fall through, since concrete doesn't fall around you. Still no picnic, though, warning signs or no. And imagining you'll be fine is pretty useless. That said, everyone should see the CN Tower before they die. InedibleHulk (talk) 15:47, June 24, 2016 (UTC)

But never ever reach back like this. InedibleHulk (talk) 15:56, June 24, 2016 (UTC)

@Aspro, while as I child I didn't experience fear of heights, I'm quite sure it's not related to an incident (that I might have forgotten). It feels totally normal to be afraid of potential dangers, and looking down from a cliff is certainly a danger. Other people are terrified by spiders and while my brain doesn't mind them I don't think it's absurd. There is a certain evolutionary advantage to having phobias. A text written in red will have drawn your attention, and you cannot "unlearn" that red texts are more important than black ones. So, I'm totally OK with my fear of heights and it's not something I have to "deal with". Last time I enjoyed a beer when my friends climb the Eiffel Tower. However, the lack of the same fear of heights in planes or on ships is IMHO interesting. I wonder if other people have that experience as well and what could be an explanation that makes sense. I think it's very well possible that small adjustments to the design of high buildings (fountains? moving art? wood? Suggesting that the building actually is a ship?) could completely undo fear of heights. One of the most common phobias must have more research than Acrophobia has. Joepnl (talk) 22:41, 24 June 2016 (UTC)

You seem to have painted yourself into a corner, which stops you standing back and looking at that -which will solve your puzzling. I stated that instincts are good and so I agree that it is not something you have to "deal with". Just pointing it that the unease can be dissolved -if you so wish. Just a 'quick think' will not do it, because if the causative events come to mind that quickly you would have already realign your mind-view of the early perceived danger; that you once or twice sensed long, long ago. Should you take the time to dissolve the unease you will thereby answer your own query by seeing how it originally took hold. P.S. Next time you’re considering climbing the Eiffel Tower, consider taking the lift instead. That option may offer more drinking time but not for beer, rather try Absinthe. A few goblets of that and you'll end up abseiling back down without ropes.--Aspro (talk) 00:21, 25 June 2016 (UTC)

I had a very unpleasant meeting with a cat as a child, but I'm not afraid of cats. I don't think the millions of people who fear heights all had some bad experience they cannot remember. Surely, I would remember "my experience" right away because it should include at least a concussion or a fracture to make heights a special thing. Anyway, I didn't come here for medical advice. I really couldn't care less about "suffering" from acrophobia. My question is just: what's so special about a floating structure that, for me at least, it removes fear of heights. I think that's really strange and worthy of more research, which I was hoping had already been done. Joepnl (talk) 13:52, 25 June 2016 (UTC)

June 24

Drinking sub-zero alcohol

I've heard that strong brandy won't freeze even at -20°C. If I were to keep a bottle at say -5 or -10°C would my mouth and throat start to freeze when drinking it considering we're mostly made of water? 78.0.252.164 (talk) 13:07, 24 June 2016 (UTC)

Frostbite of the tongue would give you a hint to stop your experiment. AllBestFaith (talk) 13:35, 24 June 2016 (UTC)

Your drink might not be cold enough to cause serious damage - but there have been serious consequences from a Liquid nitrogen cocktail Wymspen (talk) 14:02, 24 June 2016 (UTC)

Hehe, should've remembered to ask Russians :D 78.0.252.164 (talk) 21:02, 24 June 2016 (UTC)

Why do you want to drink it so cold? You will not experience the bouquet (the whole point of a snifter is to warm the liquor in ones own hands to release the bouquet ) If you want to drink sprites very cold, then go for low quality spirits like American Bourbons. Made very cheaply from maize (the US call it Corn -but the results are the same). --Aspro (talk) 15:28, 24 June 2016 (UTC)

Sounds like someone has not had much exposure to Bourbon, or at least not the right kinds. Anyway, vodka is the spirit that is commonly served ultra-cold. SemanticMantis (talk) 16:16, 24 June 2016 (UTC)

Depends on the liquor definitely. I find that whiskey is best drunk cold, except maybe for Jim Beam and similar. But then again I don't like Jim Beam much 78.0.252.164 (talk) 21:02, 24 June 2016 (UTC)

http://msgboard.snopes.com/message/ultimatebb.php?/ubb/get_topic/f/108/t/000648.html --Guy Macon (talk) 17:39, 24 June 2016 (UTC)

Probably one key reminder from that discussion is that freezers are often -15°C or lower, so anything store in them for long periods, like ice cream, sorbets, ice blocks and ice cubes are likely to be at those temperatures. Yes they're solid so won't make so good contact with the lower part of the mouth (although probably better with the upper part). And even for those which are normally eaten frozen like ice blocks, ice cream and sorbets it's normal to let them warm up slightly and eat them slowly. Still I'm sure many people even here have experience eating at least one straight from the freezer and gulping it down. As for ice cubes, I'm sure some people here have putten an ice cube straight from the freezer into their mouth, some have even accidently or intentionally swallowed one. The biggest danger would likely be choking. Heat capacity and quantities are relevant, I'm sure you could cause some injury due to the cold if you tried hard enough but generally there's no reason to think the drinks are going to be generally different. (The earlier points along with heat transfer don't seem to have been considered in the discussion about air temperatures on Snopes.) Notably, even if the alcoholic drink did freeze you could always make an ice cube or block out of that just like with water, in other words there's even less reason to think of the non freezing drink as special. Perhaps if you had something which froze at exactly -15°C (or whatever) then enthalpy of fusion would be relevant but that doesn't seem to be what was referred to and I don't think alcoholic drinks are likely to freeze or melt in a simple way anyway. P.S. It's possible Leidenfrost effect would make some difference, or there would be some effect of an insulating layer, but I don't think it's clear that will be significant for water or water mixtures or ice cream at the temperatures involved. Nil Einne (talk) 19:19, 24 June 2016 (UTC)

Thanks guys. FWIW ice cubes are fine with me even straight out of the freezer, the worst that can happen is tongue getting stuck anyway, I was more worried about cold liquid coating and freezing the whole mouth, but yeah I suppose it's not a danger at these quantities and temperatures especially with the summer heat here.78.0.252.164 (talk) 21:02, 24 June 2016 (UTC)

Very cold beverages can actually cause a burn in the mouth or throat. And such burns can lead to cancer, according to the WHO. See here. Akld guy (talk) 00:14, 25 June 2016 (UTC)

I am of Polish ancestry and can say first hand that it is very common to keep vodka in the freezer and drink shots of it immediately from the freezer, without any "freezer related" injuries. I think the "heat capacity" thing might be the key here, even half a glass would not be enough to "freeze" anything on the way down, more than half a glass at a time and I dare say you need to start worrying about things 'other' than your throat freezing. Vespine (talk) 00:31, 27 June 2016 (UTC)

Number of leads for a segmented LCD display

For 1/2 duty 1/2 bias segmented LCD displays:

1. 14 segments requires 9 pins

2. 18 segments requires 10 pins

What's the formula here?

My best guess so far is ceiling( # of segments / 2 ) + 2. Not sure if that's right or not. Johnson&Johnson&Son (talk) 15:06, 24 June 2016 (UTC)

TI's datasheet: http://www.ti.com/sc/docs/products/micro/msp430/userguid/ag_14.pdf

You need to loook for "2MUX", also "3MUX" and "4MUX". Note that this is LCDs, not LEDs. Andy Dingley (talk) 18:59, 24 June 2016 (UTC)

Thanks!

In their formula, Integer [2 + (#-of-segments/2)], is Integer() rounding up or down? Johnson&Johnson&Son (talk) 02:42, 25 June 2016 (UTC)

It would be rounding up. You need the connection whether you have one or two segments connected to it. Andy Dingley (talk) 09:12, 25 June 2016 (UTC)

Energy efficiency and speed of submarines and ships

Which can be faster and are energetically more efficient? Ships or subs? That is, comparing two which can hold the same cargo, not directly two which have the same size. --Llaanngg (talk) 19:00, 24 June 2016 (UTC)

A hint from nature is that the whale, the greatest sea mammal, travels long distances underwater rather than on the surface. See Whale#Locomotion. AllBestFaith (talk) 19:51, 24 June 2016 (UTC)

Nice hint, but there might be other non-speed, non-efficiency related reason for this. The skin or eyes could be too sensitive to travel on the surface, more food could be available deeper in the ocean, navigation might be easier underwater. --Llaanngg (talk) 23:51, 24 June 2016 (UTC)

FWIW: asked & answered on 'Yahoo! Answers' → [9] --107.15.152.93 (talk) 23:12, 24 June 2016 (UTC)

I am trying to find more reliable sources than Yahoo Answers, but thanks anyway. --Llaanngg (talk) 23:51, 24 June 2016 (UTC)

Submarines, because much of the losses are in creating waves on the surface.

In the 1960s, giant cargo submarines were studied conceptually to exploit this. However a long-submerged submarine needs nuclear power and the fuel elements for a compact reactor are also a gift for weapons production. Such a cargo submarine might also make a viable missile carrier. So, no cargo submarines.

The closest we got, in a way, was the bulbous bow which is also quite an efficient way to make a hole in water. Andy Dingley (talk) 00:01, 25 June 2016 (UTC)

Surface ships spend about half of their power to create waves. A submarine makes no waves, provided it's at a large depth compared to its diameter. Skin friction is lower for a submarine too, as it has a smaller wet hull area for the same displacement, assuming a typical beam:draft ratio for the surface ship. So the submarine is more efficient. However, a ship's size is often limited by draft. Most cargo ships are designed with the largest possible draft that still allows them to go where they have to go. At a given draft, a submarine has, because of its cylindrical hull, much less displacement and therefore loading capacity than a surface ship, which makes it less efficient. Then there's the limited safety of submarines, the nuclear material and the difficulty of loading/unloading any type of cargo except fluids or granular material, which makes them only usable for time-insensitive bulk. Using a cheap and slow surface ship works better for bulk.

Submarines have been proposed for transporting crude oil out of the Arctic, where they have the advantage of being capable of diving under the ice. But by first consuming the oil from warmer areas of the planet we managed to meld the ice cap, so there is no longer a need for that. PiusImpavidus (talk) 08:41, 25 June 2016 (UTC)

Portion size of food and nutrients

Recently, I watched Sugar Coated (2015) documentary. It was about the excessive use of sugar in the food industry to make food taste better and to compensate for the decrease in fat in order to increase sales. One man says that one piece of the fruity candy thingy has as much sugar as a candy bar or a bowl of strawberries, and argues that the vendor is marketing the candy as fruit. I paid attention to the bowl of strawberries part. I have personally eaten greater quantities of strawberries or grapes before. Counting by the amount of sugar consumed, is it possible to overdose on sugar by gorging on fruits while watching TV? 66.213.29.17 (talk) 19:41, 24 June 2016 (UTC)

Define "overdose on sugar". --Guy Macon (talk) 20:34, 24 June 2016 (UTC)

According to our article, the LD50 of sugar is 29.7 g/kg, so, a person weighing about 100 kg (rather above average for the general adult population), would need to eat three full 1 kg bags of sugar before it had immediate consequences - I doubt that's practically possible with pure sugar, let alone any sort of fruit. Of course, smaller amounts increase the risk of dental and medical problems, and the OP should see a doctor if they're worried about their health, but an actual acute overdose is unlikely. See Sugar#Sources for the numbers on various types of fruit. Tevildo (talk) 20:40, 24 June 2016 (UTC)

LD50s can vary quite a bit depending on the organism (as well as other factors about the population), I doubt we have an LD50 for sugar for humans. Maybe more important, remember LD50 is when half of the population is killed and there's pretty much nothing where half the population dies of only and precisely at a certain dose. So even if the LD50 for humans were as stated, many 100kg people are going to have immediate consequences before 3kg, including death. (Death isn't the only immediate consequence, you could have vomiting for example.) However empirical evidence would suggest if we ignore diabetics, the figure for immediate consequences would be quite high. Nil Einne (talk) 19:25, 25 June 2016 (UTC)

Hmmm... 64% of the carbohydrate calories in strawberries are sugars: fructose, glucose, and sucrose. But the glycemic index is 40, i.e. a low glycemic index food that is unlikely to cause blood sugar issues in diabetics. [10] There must be some crucial little detail here I'm not understanding... Wnt (talk) 20:46, 24 June 2016 (UTC)

If you're asking why the glycemic index is low, it's because fruit contains a buttload of fiber. --71.110.8.102 (talk) 00:13, 25 June 2016 (UTC)

And because strawberries consist of 91 percent water, meaning that there are little carbs in them. Sjö (talk) 06:45, 25 June 2016 (UTC)

Finding a cat in a big house

Hello all,

My wife and I are cat people. Currently we have one cat but she is young, small, spunky, rumbustious and very smart. We love her to death. Her objective is to get out of the house and roam outside but she is a house cat. Despite our best efforts she has managed to escape about a dozen times every time for a brief period except one, when we could not find her for about five hours. My wife went totally nuts, accusing me of neglect and threatening me with the hell's fire. Apparently she slipped between my feet when I was leaving home. It is not why I am posting though.

She has a habit of disappearing in the house for sleep. My wife sometimes spends an hour looking for her because she suspects that the cat might have escaped. I am worried also. Our house is not clattered by any means but it is impossible to find her. Then she would show up as nothing happened, almost smiling.

I know there are photo-cameras used to snap pictures of wild animals in nature during the night and I want to explore this option. I am thinking that if I install a couple of cameras like these I can eventually find out where she hides. I would appreciate any suggestions about the technology and how to use it. We simply want to have the ability to find her and make sure she is home. Thanks, ---AboutFace 22 (talk) 19:50, 24 June 2016 (UTC)

If you do a web search for [cat gps tracking], you'll find that there are collars and chip implants that might be what you need (I cannot attest to effectiveness, etc.). --107.15.152.93 (talk) 20:01, 24 June 2016 (UTC)

Before we go all New World Order here, surely it is not that hard to bell a cat (if you are not a mouse, that is). Wnt (talk) 20:49, 24 June 2016 (UTC)

Domestic cats have a habit of using one site to sleep in for a few days and then choosing another site for a while. This is presumably an adaptive strategy to avoid parasite re-infection. The reason I mention this is that if you set up camera-traps, you might find where she is sleeping at the moment, but she will move on when she feels the need and your worry will return. DrChrissy ^(talk) 20:55, 24 June 2016 (UTC)

Back in the Old World Order days, I tried a bell collar. It only encouraged the cat to move more stealthily (and of course, doesn't work when cat is asleep). --107.15.152.93 (talk) 21:35, 24 June 2016 (UTC)

I'd not go for cameras, but location devices. What's your budget? This [11] bluetooth thing might work well for in-house usage, it is designed to help you find your misplaced keys and such. If you scan around the house for a minute, it should be able to help you track the cat down. There are GPS widgets for pets e.g. [12], just google for others. You don't really need GPS to establish if the cat is in the house though, and it may be of limited value on such a small scale - the cat might be in the basement or under the couch and would look the same on GPS. On the other hand, full GPS would help you find the cat even if it left the house. Finally, in my experience, this hidey-cat behavior tends to get better with age. As the cat settles in and becomes more secure, it will probably have less need to hole up out of sight. SemanticMantis (talk) 22:20, 24 June 2016 (UTC)

Another possibility is to provide her with sleeping baskets/nests - plenty of commercial ones are available. Enclosed ones are probably the best. This might increase your chances of finding her, however, if she is like my cats, she will ignore the nests and sleep in the bloody box they came in!DrChrissy ^(talk) 22:57, 24 June 2016 (UTC)

• Unless the OP lives in the middle of a free-way junction where she could get run over by just stepping out side – why try and force her into being a house cat? Being house-bound is not in their nature. Also, what’s wrong with her getting lost in the house. Cats like a bit of solitude from time to time. The OP states that he is a cat person -so how about showing the cat some respect and don't treat her as an item (like a fridge, TV or Barbie Doll). She is a sentient being, like you and I -with a mind of her own. --Aspro (talk) 00:59, 25 June 2016 (UTC)
  • We're supposed to be wiser, and care for our pets, who are often less wise. A cat who goes outside dies sooner than those who remain in the house. And that's a decision the human makes, not the cat. Cats are perfectly happy inside. A camera or Tile (bluetooth thing) on her collar sounds like it could help allay fears that she's gotten outside and killed without invading her space. -Nunh-huh 01:19, 25 June 2016 (UTC)

Even the smartest and strongest housecat rarely fares well against a cougar. Or a fisher. Eagles are a bit easier, but why risk the embarassment of losing her to a bird? Besides, it's not like she just wants out for an innocent stroll. If we're being empathetic here, imagine what a sentient chipmunk feels like being treated like a ball of yarn. Where's the love then? Those guys have hands, man! Plenty of animals are perfectly happy inside, and only risk the world beyond to eat, screw or crap. They indeed look at housecats with envy (and horror), not pity. InedibleHulk (talk) 04:06, June 25, 2016 (UTC)

Thank you very much for the multitude of suggestions. Yes, we want her to be an indoor cat but we live in a house with large windows and the cat begins to mew in the morning asking us to open the windows and doors for her. She understands what the freedom means. That's why we are so scared. Every time she disappears for 10 hours we think she's escaped. Yes, my wife will pay any money to be able to monitor her. We actually flew her from Europe with an escort when my brother died, she was his cat. Thanks --AboutFace 22 (talk) 02:47, 25 June 2016 (UTC)

Well, you've got more of a wife problem than a cat problem. I'm not being nasty, and in fact I sympathise with her, but cats are gonna do what cats want to do.http://pettrackingoz.com.au/products/petrek-lt-905g is the sort of gizmo I'd have liked for my most recent cat, who was easily capable of sleeping in any random spot for 12 hours at a time. Don't fret about the cat running away, unless someone offers her a better option she'll be back when she's hungry or bored. Greglocock (talk) 03:39, 25 June 2016 (UTC)

So the cat grew up in Europe and now no longer lives there? I don't know about your cat specifically, but most cats in Europe are free to go outside. She may be used to it. But maybe the outside world is more dangerous where she lives now than it was in Europe. PiusImpavidus (talk) 09:03, 25 June 2016 (UTC)

Cats are gods, it is both futile and sacrilege for their human servants to want to know too much about their nocturnal perambulations and other ritual activities. Your cat has chosen you to be its slave, it may not be challenged. Roger (Dodger67) (talk) 10:43, 25 June 2016 (UTC)

Couldn't agree more with Roger. Cats have needs. Just like Maslow's hierarchy of needs. Food, shelter and warmth are not enough. “Research shows that when people live lives that are different from their true nature and capabilities, they are less likely to be happy than those whose goals and lives match.”; same for cats – let her have a life. Then she will always return home to those that provide those right basic needs. 6 Pets that Traveled Long Distances to Get Home. You could instill in her paranoia by tracking her so that your always know where she is. This over-protection that your wife strive for, drives some teenagers to leave home and brake all contact with their parents. They become missing persons.--Aspro (talk) 15:13, 25 June 2016 (UTC)

People should be left alone too make their own decision on indoor vs. outdoor cats. They really don't need advice or opinions. Far better to talk about something that nobody has a strong opinion about, like the 2016 US presidential election, climate change, abortion, or gun control. :( --Guy Macon (talk) 16:49, 25 June 2016 (UTC)

The OP is asking for opinions though - in order to be better and more responsible cat owners to a cat that they cherish and feel fond of– and the majority consensus here, is that his wife is unwittingly standing on the wrong premise and so thwarting the cat's natural instincts. Relax – let the cat be a cat and stop trolling. --Aspro (talk) 17:39, 25 June 2016 (UTC)

Cats, cats and more cats. Meow is the time! InedibleHulk (talk) 00:59, June 27, 2016 (UTC)

Comment Readers of this thread may also be interested to read another thread about introducing a cat to a new home. Wikipedia:Reference desk/Archives/Science/2016 May 18#Cat in a new home DrChrissy ^(talk) 15:45, 25 June 2016 (UTC)

@DrChrissy, I am familiar with the post you are pointing to. It actually inspired my post here. It is amazing how many emotions the cats induce in us. That post especially, my daughter's advice to keep the cat indoors for her own good and longevity, as well and some observations in our neighbourhood which is partly rural have cemented our determination to keep our treasured animal indoors. I walk around on the weekends and see domestic outdoor cats roaming around and then you see a post somewhere, cat lost. We have coyotes, hawks, etc. She is a little animal. Still her attempts to get out after looking outside through our large glass panels is heartbreaking. It is mew after mew. We are in the United States but this cat in the old country was an indoor cat and she lived on the eighth floor of an apartment building. I really appreciate all opinions. Thank you --AboutFace 22 (talk) 18:06, 25 June 2016 (UTC)

Thanks for this. In my real life, I work on the science of animal welfare, particularly captive animals. A lot of discussion on animal welfare is about frustration of their motivations. However, we must not be anthropocentric about this. We do not have the same senses and motivations as cats. We are "locked in our own skin". Do you really know that she is mewing to get outside? When my cats see a bird through the window, they stay where they are and "chatter" at them through the glass, choosing not to go through my propped-open door which is only 3 metres away to chase them. Keeping your cat indoors to prevent her from being predated is certainly improving your cat's well-being, but animal welfare is widely considered these days to be about the animal's feelings. If your cat is not getting frustrated at being unable to get out, all is well. However, if your cat is frustrated, this could be having a negative effect on her welfare (please do not take this as an accusation whatsoever of wrong-doing on your part - I am simply putting forward an academic argument). DrChrissy ^(talk) 19:59, 25 June 2016 (UTC)

June 25

Having Only Bread and Water = Plugging Up Gastrointestinal Tract?

On an episode of NCIS, it was mentioned that an old naval punishment involved feeding offending sailors only bread and water for a week, in order to plug up their gastrointestinal tracts. In real life, will such a diet really have the aforementioned consequences? 173.68.173.114 (talk) 03:41, 25 June 2016 (UTC)

I'm not aware of any such effect, and don't see why it would be the case -- however, such a diet would lead to malnutrition over time. 2601:646:8E01:7E0B:BC8F:CE52:F743:E9A9 (talk) 04:31, 25 June 2016 (UTC)

Yeah, that seems like pretty typical bad fact-checking on an apocryphal tale. No basis in physiological reality whatsoever. Point in fact, the bread of the era being likely to be high in fiber, it is more likely to have pulled additional moisture into the bowel (leading to looser stools) when compared against much of the rest of the preserved fair that pre-modern navies depended upon. Quite the opposite to the scenario presented, it would be the withholding or limiting of water rations (rather than providing an excess of water and fiber) that would be most likely to induce constipation in that scenario. Certain varieties of bread might have had the desired effect, but the last thing a naval vessel would ever want was to punish through means that would then require additional and highly valuable quantities of water to reverse, especially when withholding those same rations from the start would be a more effective punishment (being at sea with minimal water borders on one of the most physically unpleasant states of being manageable for a human being).

Interestingly enough though, modern navies prefer to punish their malcontents by making them watch episodes of NCIS. ;) Snow ^{let's rap} 06:26, 25 June 2016 (UTC)

Bread and water punishment was available in the US Navy until 1995 - see Non-judicial punishment. I don't know how often it was used during the 20th century, though. Tevildo (talk) 11:07, 25 June 2016 (UTC)

Apparently resurrected for civilians in Maricopa County, Arizona in 2014, according to this news article. Alansplodge (talk) 11:44, 25 June 2016 (UTC)

Although it was removed as an authorized punishment by USN court-martial in 1995, confinement on diminished rations or bread and water for not more than 3 days is still an available non-judicial punishment which may be imposed on US sailors and Marines of rank E-3 and below who are attached to or embarked in a vessel. -- ToE 12:27, 25 June 2016 (UTC)

Yes, just so. Reduced rations, especially radically reduced rations at sea, are always bound to be a much more feared punishment than being given just water and bread, but plenty of it. Snow ^{let's rap} 14:02, 25 June 2016 (UTC)

Main Battle Tanks -T-14 Armata

I studied the design of T-14 and I found a problem , the designers made an unmanned turret so they put the commander`s position in the front , but I imagined a scenario as this : the tank`s panoramic sight is disabled , the driver`s rear camera is disabled , the crew can`t see what`s behind them , do you consider this a big problem ? 94.249.115.70 (talk) 10:39, 25 June 2016 (UTC)

See T-14 Armata for our article. Your concerns are mentioned (with references) under "Sensors and communication". Tevildo (talk) 10:42, 25 June 2016 (UTC)

The Armata is probably Israel's best design of MBT. The trouble is that it's Russian.

The Armata concept is that of the Merkava, but even more so: the crew are the most valuable aspect so must be protected. It assumes the opposition are poorly supplied, few in number and easily discouraged. Yet Soviet tactics have always favoured the meatgrinder. Nor has Soviet ability to deliver a technical fix, and the untried Russian ability, ever been convincing.

In any combat, a working Armata wins the first round. But repeated attacks can attrite any such system of reactive armour. A rain of mortar shells will do it, so long as there are also enough mortarmen to deliver them. After a few rounds of such defence, the Armata is much less well protected.

There's also the question of whether an Armata can get to the battlefield and how much working electronics it brings along with it. You'll notice they've kept the glass viewing periscopes. Andy Dingley (talk) 11:35, 25 June 2016 (UTC)

So it`s an impractical tank as I supposed.94.249.115.70 (talk) 11:40, 25 June 2016 (UTC)

_If_ it works, it's great. Andy Dingley (talk) 14:45, 25 June 2016 (UTC)

That`s it .94.249.115.70 (talk) 20:58, 25 June 2016 (UTC)

Primitive semi-radius tachyons

As they almost said in The Matrix, for this mission we're going to need drugs... lots of drugs. Or science, if you're into the hard stuff. Pass those red pills and buckle up, cause Kansas is going bye-bye!

From "String Theory Co-Founder: Sub-Atomic Particles Are Evidence the Universe Was Created", CBS News:CNS News!

"Dr. Michio Kaku ... says theoretical particles known as “primitive semi-radius tachyons” are physical evidence that the universe was created by a higher intelligence."

After analyzing the behavior of these sub-atomic particles - which can move faster than the speed of light and have the ability to “unstick” space and matter – using technology created in 2005, Kaku concluded that the universe is a “Matrix” governed by laws and principles that could only have been designed by an intelligent being.

CBS refers me to a paper that I'm not getting in a readable form and this blog which makes its own curious claims like

Michio Kaku used a new technology created in 2005 that allowed him to analyze the behavior of matter at the subatomic scale, relying on a "primitive semi-tachyon radio." Tachyons ... are theoretical particles able to "take off" the matter of the universe or the vacuum contact with it, thus leaving the matter in its purest form, totally free from the influences of the world around them.

But what is this stuff? I mean, how are "primitive semi-radius tachyons" defined, what does that even mean? What is the new technology from 2005? What the hell is taking off? And so on... Wnt (talk) 14:42, 25 June 2016 (UTC)

Update: I have two sites [13] [14] which say that "primitive semi-radius tachyons" is a news garble that was never actually said - what was said is not so clear. But that doesn't take away from the weirdness of unsticking matter, matter in its purest form &c. Wnt (talk) 14:53, 25 June 2016 (UTC)

A Tachyon is a hypothetical particle that moves faster than light. Faster-than-light particles cannot exist because they violate the known laws of physics. AllBestFaith (talk) 14:57, 25 June 2016 (UTC)

It's plausible that Kaku would talk about tachyons. Tachyon condensation is real physics (it's part of the Higgs mechanism), and Kaku is fringy enough to believe in the faster-than-light kind of tachyons also. It's the "primitive semi-radius" part that makes no sense. -- BenRG (talk) 18:13, 25 June 2016 (UTC)

If tachyons do not interact in any way with normal matter or energy (and thus can never be detected or observed) they violate no laws of physics. Alas, the existence of such a tachyon can never be proven or disproven. --Guy Macon (talk) 18:18, 25 June 2016 (UTC)

I think this post by Franck Parra may be the origin of this. Here are some of his other posts, for comparison. It looks like "The Blog of Mystica" may have, for some reason, edited Parra's stream-of-consciousness writing into something more reminiscent of a press release, and republished it.

In any case, it is gibberish. Maybe it's vaguely related to something Kaku once said as filtered through the head of a crazy street person, but it's probably a waste of time to try to figure it out. -- BenRG (talk) 18:13, 25 June 2016 (UTC)

Wow. That 2013 posting definitely forms a clade with this news article, though the authors are not the same. I realize now this was CNS News - I hadn't looked closely before and for some reason I'd thought it was some local CBS affiliate. It is apparent that they are in serious need of scientific help. Wnt (talk) 20:11, 25 June 2016 (UTC)

I still suspect that Parra's post was the origin of this in English, but here's a version from November 2009 in Portuguese (which is probably Parra's native language). "Primitive semi-radius tachyons" has to be a garbled translation of "semi-raio primitivo de táquions". I don't know Portuguese (I do know some Spanish), but the only occurrence of "semi-raio" in the Portuguese Wikipedia is in Hilbert's axioms where the English article uses "ray" in its geometric meaning of a half line. I wonder if that Portuguese phrase is itself a garbled translation of something like "primordial ray of tachyons", which is a phrase that Michio Kaku might actually utter.

This version also says "the complete theory will be presented on January 9, 2010, at a conference in Switzerland", and credits the story to Scientific American. I doubt that Scientific American would publish anything resembling this story, and I can't find the conference. -- BenRG (talk) 00:34, 26 June 2016 (UTC)

Some Spanish-language sites, such as [15], attribute this story to "Jornal VDD", which is a fake-news publication from Brazil (it's mentioned in pt:Noticiário satírico). I bet that's the real origin. -- BenRG (talk) 01:50, 26 June 2016 (UTC)

NEMO as an illness

Trying to get data to fill out the description for File:North Livingston Baptist Church.jpg, I found their Facebook page, which had a request for people to be tested for a bone marrow donation. Part of that statement says This drive was set up for Mason, a local boy with NEMO, which is even more rare than HLH. HLH I suppose is Hemophagocytic lymphohistiocytosis, but what could NEMO be? NEMO lists a lot of things that aren't relevant; I suppose it could be a reference to a problem with IKBKG, but that seems a bit of a stretch. Nyttend (talk) 14:54, 25 June 2016 (UTC)

http://www.gosh.nhs.uk/medical-information-0/search-medical-conditions/nemo-deficiency-syndrome -- Finlay McWalter··–·Talk 15:02, 25 June 2016 (UTC)

I created a "stub" article based on that reference at NEMO deficiency syndrome and added a link in the disambiguation page for NEMO. Hopefully more information can be added there as it becomes available. One of the things that makes the ref desk useful is in finding gaps in Wikipedia's coverage - so this kind of question (and our response to it) is important to us. SteveBaker (talk) 17:33, 25 June 2016 (UTC)

Momentum conservation

This discussion has been closed. Please do not modify it.
The following discussion has been closed. Please do not modify it.
[section header added:107.15.152.93 (talk) 18:41, 25 June 2016 (UTC)] If there are any mistakes in the following supplement for Momentum conservation, please correct them. [The Supplement] In a closed system (one that does not exchange any matter with its surroundings and is not acted on by external forces) the total momentum is constant.(the momentum conservation 1st law) However, only in case of a physical system (called a newly semi or sub-closed system) that does allow certain types of transfers (such as transfer of mass and/or matter) inside the closed system, the total momentum is "variable".(the momentum conservation 2nd law) There are the following justifiable reasons. In the first place, the law of momentum conservation has been implied by a principally action-reaction law as below. [The mainly existing definition of the Newton’s third law] ~When one body exerts a force on a second body, the second body simultaneously exerts a force equal in magnitude and opposite in direction on the first body.~ However, the above law should be reformed (revised) as follows because it isn't so easy to distinguish the action-reaction forces from the equilibrium of forces in the above fixed definition. ~When one body (A) exerts an action force on a second body (B), the second body (which does not exert an action force by itself) simultaneously exerts a reaction force equal in magnitude and opposite in direction on the first body. And when A body’s action force interacts with B body’s action force, the equilibrium of forces between A & B are lost in case of (the initial) unbalanced momentums of the both bodies. But, each body receives a reaction force equivalent to the action force by its body from the other body.~ Note : The force (F or -F)’s reference value for an equation of momentum conservation in a collision of two bodies is chiefly based on a measure of one body’s action force (F) or reaction force (-F). That doesn’t indicate a pair (equal) of A body’s reaction force & B body’s action force in case of applying a pair (equal) of A body’s action force & B body’s reaction force as to F=-F.　 So, it is necessary to be careful of being in “uniform motion”, not “at rest” in the law of inertia for the united body in case of causing a perfectly inelastic collision by unbalanced action forces of the two bodies. As for the above important matter, even a main (hollow) body in the sub-closed system (just like EmDriving machine) that does allow certain types of transfers (such as transfer of mass and/or matter) in the same system under the momentum conservation law (which is similar to the law of inertia) could be applied. That means one and the same body may move at a constant velocity, not remaining at rest, once it produces some internal pressure difference (unbalanced forces) inside (at both ends of) the hollow body. The movement has been already proved with the successful EmDrive tests by NASA etc. — Preceding unsigned comment added by More-kenlouise (talk • contribs) 18:15, 25 June 2016 (UTC) Nonsense. See: NASA: Is Warp Drive Real?] You Still Shouldn't Believe in the emDrive Did NASA Validate an “Impossible” Space Drive? In a Word, No. No, NASA has not verified an impossible space drive! "The concept gained considerable press attention in 2015, after someone at NASA lab Eagleworks, which specialises in investigating almost-certainly-wrong Hail-Mary ideas on a 'what if' basis, tried out the idea and the press went nuts with the notion that this constituted NASA endorsing it." 4 Reasons Why The EM Drive is Probably Bullshit RF resonant cavity thruster#EmDrive --Guy Macon (talk) 21:19, 25 June 2016 (UTC) What? Nonsense!? What do you mean by...?? I (More-kenlouise) have asked about any mistakes in the above matter. You cannot correct them at all??? — Preceding unsigned comment added by More-kenlouise (talk • contribs) It is quite hard to understand what you wrote. Sentences like "That doesn’t indicate a pair (equal) of A body’s reaction force & B body’s action force in case of applying a pair (equal) of A body’s action force & B body’s reaction force as to F=-F" are almost incomprehensible. You seem to be arguing that A's "action force" on B should be distinguished from B's "reaction force" on A. But there is no such classification of forces in Newtonian physics. You also seem to argue that with A and B each acting on each other, and each reacting to the other's action, there could be unbalanced forces. But that isn't true. If A acts on B with a force FAB and B acts on A with a force FBA and there are matching reaction forces, then the total force on A (action+reaction) is FBA + (-FAB) and the total force on B (action+reaction) is FAB + (-FBA), and those are negatives of each other. -- BenRG (talk) 05:17, 26 June 2016 (UTC) A's "action force" on B should be distinguished from B's "reaction? force" on A?? That isn't true. A's "action force" on B should be distinguished from B's "action force" on A. Read the following sentences. ~When one body (A) exerts an action force on a second body (B), the second body (which does not exert an action force by itself) simultaneously exerts a reaction force equal in magnitude and opposite in direction on the first body. And when A body’s action force interacts with B body’s action force, the equilibrium of forces between A & B are lost in case of (the initial) unbalanced momentums of the both bodies. But, each body receives a reaction force equivalent to the action force by its body from the other body.~ — Preceding unsigned comment added by More-kenlouise (talk • contribs) 06:15, 26 June 2016 (UTC) ‎ More-kenlouise, I just gave you several links correcting the many mistakes in your claims, particularly your false claim that "the movement has been already proved with the successful EmDrive tests by NASA etc". Read them. I especially recommend the article at [ http://www.popularmechanics.com/science/a15323/temdrive-controversy/ ]. Also, read the warnings at User talk:More-kenlouise#June 2016. If you continue your disruptive behavior you will be blocked from editing Wikipedia. --Guy Macon (talk) 05:26, 26 June 2016 (UTC) And still, you cannot correct ... at all???? If so, you are disqualified for blaming me!!! — Preceding unsigned comment added by More-kenlouise (talk • contribs) 13:42, 26 June 2016‎ (UTC) Call for close Could an uninvolved editor please close this thread? Clearly we have WP:CIR and WP:IDHT issues here, and any further disruptive behavior should be be addressed at WP:ANI Disruptive behavior!? That's a bit much. How did More-kenlouise take any more of such a behavior? Do explain it before the closing!! — Preceding unsigned comment added by More-kenlouise (talk • contribs) 18:37, 26 June 2016 (UTC)

selective amidation

Here's something I wasn't taught in chemistry class: I have a peptide containing serine, tyrosine and a C-terminal proline. I wish to amidate this proline residue with ethylamine (not necessarily directly), but without functionalizing the tyrosine and serine residues. Is this possible without use of expensive protecting groups? Yanping Nora Soong (talk) 18:16, 25 June 2016 (UTC)

GFCI mystery

I recently installed an electrical outlet on my outdoor deck. Naturally I used an outlet with an integral Ground Fault Circuit Interrupter. (110 VAC, North American practice.) It's a brand-new, commercial grade, heavy-duty, 20 amp, outdoor-rated outlet. I assume it has the latest and greatest circuitry, it even has a little LED indicator that glows green when it's working correctly. I installed it in a weatherproof outdoor box with a weatherproof outdoor cover, whole nine yards.

But the first time I tried to use my portable circular saw with it, it tripped immediately. This was 100% repeatable: every time I reset it and tried the saw again, it tripped again.

The saw works fine in a different GFCI outlet, and it's a double-insulated saw with a 2-wire plug, so it's unlikely to have a ground fault. I considered that I might have wired the outlet incorrectly (it's all too easy to wrongly connect the supply lines to the downstream load terminals), but I double checked, and it's fine.

I wondered if commutator noise from the saw's 15-amp motor might be tricking the GFCI's sensitive detection circuit into tripping. I grabbed a heavy-duty extension cord (12 gauge wire, 25 or so feet long) and plugged the saw into that and the cord into the outlet, imagining that perhaps the cord's inductance might be enough to filter out the noise and keep the GFCI from tripping.

It worked! I've been using the saw all afternoon, and the GFCI has only tripped once.

So my questions are, has anyone heard of this problem, is my diagnosis accurate, and is the extension cord's inductance likely to be helping? (Or is there something else completely different going on?) —Steve Summit (talk) 18:59, 25 June 2016 (UTC)

Did you put this outlet on a circuit that already has a GFCI at the panel? I've found this can cause problems. Shock Brigade Harvester Boris (talk) 19:02, 25 June 2016 (UTC)

I've been having troubles with GFCI's at my home - four of them (two in the kitchen, one in the garage and one in the bathroom) would trip all the time with a variety of different appliances - sometimes consistently, sometimes just at random. The others are in places where we rarely use them - so it's possibly that they have problems also.

I asked around about the problem - and was told by an "experienced electrician" over on Quora that very often the problem is when the GFCI has additional outlets attached "downstream" of it using the "LOAD" terminals. The explanation was not very coherent (the guy had evidently been taught that this isn't an ideal arrangement - but didn't seem to be able to explain why). He recommended replacing all of the outlets in places like workshops and kitchens with individual GFCI's rather than sharing a single GFCI among several outlets.

That seemed like a painful thing to have to do (we have ~100 outlets and GFCI's cost ~$10 each!) - and so I first tried replacing one of the troublesome GFCI's with a brand new one. Result: No more tripping out with any of the troublesome appliances. So then I replaced the other three problematic ones - and now I have no problem with those either. In the course of doing that, I found one that had been incorrectly installed ("LINE" and "LOAD" were swapped) - and one that had (worryingly) been wrapped around with half a dozen layers of painter's tape to prevent it from coming in contact with a grounded metal box in the wall that had evidently been bent during installation! (Yeah - not even electrical tape!)

However, I'm becoming convinced that either these things get worse with age (although my house is only 10 years old) - or that there are some cheap/nasty brands that should be avoided - so as I have time, I'm gradually replacing all of the GFCI's in my house with new ones...not least because I fear other "botched" installations.

What I imagine would be the best course of action for you would be to disconnect the "downstream" outlets from the GFCI and see if it'll still trip with your saw. To be honest, I prefer to have separate GFCI's on all outdoor outlets anyway and at $10 each, there isn't really a good reason not to do that.

Failing that, you could also try replacing the GFCI with one from a different brand.

SteveBaker (talk) 19:37, 25 June 2016 (UTC)

You may want to invest in some higher quality GFCIs rather than the cheap $10 units you are considering. In my professional opinion (I am an electrical engineer), the GFCIs listed here are the best available. --Guy Macon (talk) 20:02, 25 June 2016 (UTC)

In my case, there is not a GFCI in the panel upstream of the outlet in question, and no additional loads downstream.

The outlet in question is name brand (Leviton), and was not inexpensive -- closer to $20 U.S., I believe. —Steve Summit (talk) 11:36, 26 June 2016 (UTC)

You started an inductive load (a large motor), which is a recognised problem for use with GFCIs. Some ratings will be less sensitive to such inductive loads (there may be deliberate time delays etc.), but it's unlikely that a consumer grade socket will be doing this. Also it's a general rule for such things that the integral types are more cheaply made and less reliable than the better grades, which are only available as separates. Also outdoors is a poor environment for switchgear anyway, so installing the breaker indoors at the panel may be more reliable.

Also, even though double insulated, I'd PAT test the saw, specifically the insulation. Hand-held power tools get a hard life. Andy Dingley (talk) 20:12, 25 June 2016 (UTC)

Thanks, Andy. I used to like the panel-mount interrupters, but I've gotten the strong impression that everybody else wants to be able to see at the outlet that it's a GFCI, not have to rely on someone's assurance that there really is one wired in somewhere else. —Steve Summit (talk) 11:36, 26 June 2016 (UTC)

I don't know this topic, but I'm suspicious the saw simply has very low resistance when the current first starts flowing (i.e. inductive load). If so, is it the added inductance of the electric cord that matters, or simply the resistance? For that matter, I wonder if you took some steel wool and burnished the plug on that cord until it looked like it was freshly bought, whether it would stop preventing the GFCI from going off. Not sure you want to try that :) Is there any little gizmo available that can be put on the end of a plug or into a light socketelectrical outlet that provides extra resistance for about one second only, then drops to near zero, specifically to stop such troubles? I'm thinking of something that would decrease in resistance drastically when heated for example, or it could be solid state. Wnt (talk) 21:37, 25 June 2016 (UTC)

This would be something like a Motor soft starter. The ones I'm familiar with are panel-type devices or are attached to the motor itself, not plug-in consumer-grade products. Shock Brigade Harvester Boris (talk) 22:11, 25 June 2016 (UTC)

See also: load controller (or not) ... Try a web search, I guess. This might be a solution, but I'm not an electrical engineer. --107.15.152.93 (talk) 00:42, 26 June 2016 (UTC)

Reducing the switch-on current to a motor will reduce its starting torque, possibly causing it to stall. AllBestFaith (talk) 17:57, 26 June 2016 (UTC)

My anecdotal experience (FWIW) relates to an HVAC motor with a similar problem, which was fixed by a load controller. --2606:A000:4C0C:E200:DCE4:1C76:57D1:F610 (talk) 18:33, 26 June 2016 (UTC) [aka:107.15.152.93]

You won't stall a saw at switch-on, because they're disconnected from the load when started, then pushed mechanically into it. You might do this with a device that can't disconnect its load.

It's typical for woodworking machinery (i.e. fixed machines) that cheap ones use universal motors (brushed), larger ones use induction motors. Universal motors offer higher starting torque and much higher starting torque / cost. They also only need simple switches, not starters. They do though have high inrush currents, violent starting with a snatch, and are much noisier. For woodworking there's a good example of this for table saws, where a portable "contractor saw" has a lightweight pressed steel table and a universal motor. The otherwise similar joinery workshop "cabinet saw" instead uses a heavy cast iron table, an induction motor and a price up to ten times higher. Andy Dingley (talk) 13:12, 27 June 2016 (UTC)

The inductance of a 25 foot extension lead has a trivial effect at 60 Hz, so that's not what's solving the problem. The resistance of the lead is reducing the Inrush current, the current that flows when the motor's armature is stationary. As soon as the motor starts turning, the current drops dramatically. Akld guy (talk) 21:04, 26 June 2016 (UTC)

June 26

Std transmission

Why is it that the incidence of stds spread through oral sex is much lower than that spread through vaginal or anal sex? Shouldn't it be the same given that many diseases spread through the mouth including common colds, stomach bugs etc? 82.17.228.64 (talk) 08:28, 26 June 2016 (UTC)

See Wikipedia:Reference desk/Archives/Science/2015 September 6#Std statistics and Transmission (medicine). Nil Einne (talk) 13:23, 26 June 2016 (UTC)

Maybe that London-based drive-by didn't like the answers he got a year ago? ←Baseball Bugs ^{What's up, Doc?} carrots→ 20:28, 26 June 2016 (UTC)

Bacteria and viruses have evolved to function in certain conditions - and they do less well if the conditions are different. Bacteria which transmit gastric diseases are happy to be swallowed - the can cope with the saliva and the stomach acid. Other bacteria are much less likely to survive that. In the same way, the organisms which produce STDs have evolved to thrive in the conditions in the genitals. Wymspen (talk) 21:48, 26 June 2016 (UTC)

2016 HO3

Our article on 2016 HO3 says "...this small asteroid is caught in a game of leap frog with Earth...". Why is this pointed out? Isn't that basically what most moons, including our own, do? I'm having trouble figuring out how this orbit is much different from our moon's orbit. Dismas|^(talk) 13:31, 26 June 2016 (UTC)

As the article explains: In its yearly trek around the sun, asteroid 2016 HO3 spends about half of the time closer to the sun than Earth is (that is, the asteroid is inside the Earth's orbit) and passes ahead of our planet, and about half of the time farther away (crosses outside Earth's orbit), causing it to fall behind. Its orbit is also tilted a little, causing it to bob up and then down once each year through Earth's orbital plane. AllBestFaith (talk) 13:37, 26 June 2016 (UTC)

For some reason our article doesn't mention it, but I've read that 2016 HO3 is well outside Earth's Hill sphere, the region it dominates in the attraction of satellites. The Sun is pulling more strongly on the object than Earth is. So really Earth and the object are simply orbiting the Sun on roughly the same orbit, pulling on each other along the way in such a way that the description quoted by AllBestFaith applies. Loraof (talk) 14:23, 26 June 2016 (UTC)

(ec) I think the issue here is that a quasi-satellite is outside the Hill sphere and therefore is not in a stable orbit around Earth. The best example is 2003 YN107, which went around the Earth like a moon at 0.1 AU, but then transitioned after a few years to a horseshoe orbit like many other quasi-satellites currently have. This satellite likewise, long term, exists in an equilibrium between horseshoe and moonlike orbits. I think the best way to visualize it is by comparing the video diagram for 2016 HO3 to that for Cruithne. Both asteroids have orbits with the same period as Earth; that doesn't change. But what differs is that one is constantly ahead of Earth when the two go near each other, while the other goes ahead and behind. If they were at a different point on their orbits around the Sun - but with the same orbits - they'd change apparent geometry. Wnt (talk) 14:26, 26 June 2016 (UTC)

2016 HO3 is not in Earth orbit, but in solar orbit in a 1:1 orbital resonance with the Earth's orbit, which happens to loop around Earth. It's outside Earth's Hill sphere and not gravitationally bound to Earth. This has an important consequence: 2016 HO3's "orbital period" around Earth of 1 year is far too short for an object at that distance. Edit: this is the synodic period. The siderial period is infinite, which doesn't obey Kepler's third law either. 2016 HO3 is not stationary relative to Earth, so if the sun disappeared it would probably still fly away. If the sun would suddenly disappear, the Moon would remain in orbit around Earth, but 2016 HO3 would fly away. PiusImpavidus (talk) 14:59, 26 June 2016 (UTC)

I'm trying to keep all my best faith that you're not just taking a jab at me by telling me what I've already read.

So, if you combine what I quoted plus what AllBestFaith quoted, you basically get all of what the article states. Great. Fine. Now, how is HO3 different from our own moon in the "spends half the time closer to the sun and half farther" part? Unless I'm wrong, our moon does exactly that. Why go through this leap frog analogy?

And the other explanations here about the Hill sphere make sense, so thanks for that. Dismas|^(talk) 20:25, 26 June 2016 (UTC)

• .

It has been argued that analogies are "the core of cognition", and they are a valuable way to introduce familiarity in technical explanations. The talk page for the 2016 HO3 article is where you try to persuade other editors not to use the "leap frog" analogy that NASA has used. AllBestFaith (talk) 11:35, 27 June 2016 (UTC)

@PiusImpavidus: It think this is a sort of complicated point, having to do with sidereal versus synodic orbital period. For example, the Moon masses 7.342E22 kg, Earth masses 597.237E22 kg, M = Me+Mm = 6.04579E24 kg total. Semimajor axis is 3.84399E8 m. G is 6.674E-11 N m2/kg2. Orbital speed is sqrt ( G * M / r) = sqrt (1049680 N M /kg) = 1024.539 m/s. To go roughly 2 * pi * 3.84399E8 m therefore takes about 2357402 s = 27.284 days, which given the approximation of a circular orbit is pretty damn close to the actual 27.321 day actual sidereal period. But actually look at the Moon and of course it gets an extra revolution a year that changes this value. With the small quasi-satellites, any "true" orbital speed is extremely slow, so this synodic correction dominates. At least, I think that's the explanation. Wnt (talk) 11:16, 27 June 2016 (UTC)

Indeed, the 1 year orbital period of 2016 HO3 is its apparent synodic orbital period around Earth (it slipped my mind in my previous post), which is a retrograde orbit, as much as it's its real siderial orbital period around the Sun. For retrograde satellites the number of synodic revolutions per year is always one more than the number of siderial revolutions (for prograde satellites like the Moon it's one less), and indeed the apparent siderial orbital period of 2016 HO3 around Earth is infinite, which again tells us it cannot be a real orbit. Viewed from Earth, 2016 HO3 is always in the same part of the sky relative to the distant stars. It only orbits the Earth in a rotating frame of reference in which the direction from the Earth to the Sun is fixed.

I hope this explanation doesn't make things even more complicated. PiusImpavidus (talk) 12:45, 27 June 2016 (UTC)

You put your finger on a problem with my explanation. How can 2016 HO3 always be in the same direction from Earth relative to the stars? That would mean the center of its orbit is not the center of Earth's orbit! But actually the asteroid loops around Earth at different distances, and eventually it goes into a horseshoe orbit, and I'm thinking if I played around watching simulations of the orbits it would eventually make sense that this has to happen in order for its orbit to be centered on the Sun, but I'm not at all sure about that.

But the motion also reflects that it doesn't have a real "1 year orbital period" since that orbit does change year to year; I suspect it differs from a stable 1 year orbit by just enough to account for its tiny "true" orbital speed. It varies between 38 to 100 times the distance of the Moon, so its orbital period should be something like 70^3/2 longer than the Moon's, or something like 43 years. Of course, using that simple approximation for a circular orbit in this situation is bonkers, but it's a point of comparison. Apparently it has been thought to have "revolved" around Earth for less than a century and will continue to do so for centuries, so this "period" is (barely) within an order of magnitude of actual relevant changes to its orbit. Wnt (talk) 13:09, 27 June 2016 (UTC)

The Earth's orbit is almost circular, but this asteroid has a distinctively elliptical orbit. The Sun is at one of the focal points of the ellipse, just as Kepler's first law dictates. The semi-major axis of its orbit is the same and its orbital period is too, exactly as Kepler's third law dictates. It is in a 1:1 resonance with Earth. And just as Kepler's second law dictates, it moves faster when closer to the sun than Earth and slower when farther away.

So suppose we look from a great distance onto the Sun's north pole. We put the face of a clock on the Earth's orbit in such a way that 2016 HO3 reaches its perihelion at 12 o'clock. When the Earth is at 12 o'clock, the asteroid also passes at 12 o'clock. As the asteroid is at perihelion, it moves faster than the Earth and overtakes it. At this point, it's below Earth on the clock face. Next, we wait 3 months. The Earth reaches 9 o'clock (moving counterclockwise). The asteroid has overtaken Earth and has just moved to a distance from the sun a bit farther than Earth. So it's ahead of Earth at nearly the same distance from the sun, and on the clock face still below Earth. Wait another 3 months, and the Earth is at 6 o'clock. The asteroid is at aphelion, moving slowly and being overtaken by Earth. It's farther away from the Sun, so on the clock face still below Earth. 3 months later, the Earth is at 3 o'clock, the asteroid is picking up speed and passing behind Earth, still below it on the clock face. Seen from Earth, the asteroid moves a bit to the east and west and to the north and south, in a figure-8 loop, as the orbits are not exactly in the same plane, but it always remains in the same general area of the sky.

2016 HO3 is not bound to the Earth and would, if the Earth, the Sun and the asteroid were the only parties involved, stay forever in this resonance, even if the Earth had no gravity acting on the asteroid. There is some gravitational interaction between both, and that is what locked 2016 HO3 into this resonance and keeps it there despite disturbances from elsewhere. Those disturbances exist, primarily Jupiter's gravity, flexing the asteroid's (and Earth's) orbit so that the apparent orbit of the asteroid around Earth changes. Precession of the orbits, which proceed at different rates for Earth and 2016 HO3, also causes some of the variation.

At some point in the future Jupiter and Saturn might pass at the right point in their orbits just as 2016 HO3 passes the right point in its orbit, which may speed up or slow down 2016 HO3 just enough to break out of its 1:1 resonance. It will then be in an orbit slightly wider or slightly smaller than Earth's orbit. When that happens, the Earth's gravity may put it in a horseshoe orbit, exchanging some orbital energy whenever it comes close. PiusImpavidus (talk) 19:17, 27 June 2016 (UTC)

All this stuff is a little TL;DR for me. Let me give my quick understanding, and someone can tell me if it's blatantly wrong.

• First of all, all these distinctions about which body is orbiting which are a little bit arbitrary, as these are all special cases of the three-body problem or even the n-body problem.
• That said, the difference between 2016 HO3 and the Moon is that, if the Sun weren't there, the Moon would still orbit the Earth pretty much the same way it does now, whereas 2016 HO3 would drift away.
• Defining what this counterfactual means precisely is a little tricky and, again, a little arbitrary. But (at least to a Newtonian approximation) you could probably say something like this: At some times (possibly all the time?) the velocity of 2016 HO3 wrt to the Earth is greater than its escape velocity from the Earth at that position, whereas this is never true of the Moon.

Is that basically right? --Trovatore (talk) 19:36, 27 June 2016 (UTC)

If a person gets an orchiectomy & has an extra testicle (plus epididymis), then can this person's vas deferens re-canalize & attach to this extra testicle (or to this extra epididymis)?

Any thoughts on this? Futurist110 (talk) 17:52, 26 June 2016 (UTC)

The article Polyorchidism describes what can be sourced about the rare incidence of more than two testicles. A supernumerary testicle may be functional or non-functional. AllBestFaith (talk) 18:14, 26 June 2016 (UTC)

I am talking about one's vas deferens re-canalizing and attaching itself to one's extra testicle, though. Futurist110 (talk) 19:23, 26 June 2016 (UTC)

This is actually about logic, and the laws of probability, rather than about biology or medicine. It has to be hypothetically possible that this could happen - but that does not prove that it ever has happened or that it ever will happen. The human body is so variable, and unpredictable, that it is impossible to say that a given situation could never possibly happen. However, if you wanted to calculate odds of it actually happening, it would be as near to zero as makes no practical difference. Wymspen (talk) 20:15, 26 June 2016 (UTC)

So, would lifetime insurance for child support in the event that this will indeed occur be extremely cheap? Futurist110 (talk) 23:00, 26 June 2016 (UTC)

This is a question for an Actuary. Vespine (talk) 01:41, 27 June 2016 (UTC)

OK. Also, let me guess--is the question of whether or not it is possible to remove my *entire* vas deferens during an inguinal orchiectomy a question for a doctor? Futurist110 (talk) 02:22, 27 June 2016 (UTC)

I don't think reputable doctors do "elective" orchiectomies, as it's unnecessary surgery.

If so, then I'll go to a non-reputable doctor. Indeed, abortions certainly aren't the only surgeries which can be performed in 'back-alleys"! Plus, in regards to unnecessary surgery, how about doctors stop performing elective cosmetic surgeries, eh? After all, those surgeries are also unnecessary surgeries! Futurist110 (talk) 06:46, 27 June 2016 (UTC)

If you want to be sterilized that's what a vasectomy is for.

Except a vasectomy is certainly an extremely shitty form of birth control due to the fact that vasectomy doctors themselves certainly don't have full confidence in their own surgeries! Thus, how exactly can I have full confidence in these doctors' surgeries? Futurist110 (talk) 06:46, 27 June 2016 (UTC)

Also, I don't think insurers write child support insurance. I've certainly never heard of it. One major reason is probably the inherent moral hazard; someone could get child support insurance, then go out and have a ton of children.

What about Lloyd's, though? Also, how exactly would such fraud work with a prior orchiectomy? Futurist110 (talk) 06:46, 27 June 2016 (UTC)

Why are you so obsessed with child support and sterilization?

Because child support will certainly result in a lot of harm for me. Futurist110 (talk) 06:46, 27 June 2016 (UTC)

If you don't want to have kids, get a vasectomy or use other birth control.

The thing is, though, that all non-drastic forms of birth control can and sometimes do fail. Futurist110 (talk) 06:46, 27 June 2016 (UTC)

The probabilities of a vasectomy or properly-used, high-quality birth control failing are so minuscule they're not worth thinking about. --71.110.8.102 (talk) 05:08, 27 June 2016 (UTC)

Then how about vasectomy doctors man up and agree to pay all of their patients' child support for 18+ years in the event of a vasectomy failure, eh? After all, according to you, "[t]he probabilities of a vasectomy or properly-used, high-quality birth control failing are so minuscule they're not worth thinking about." Futurist110 (talk) 06:46, 27 June 2016 (UTC)

Have to agree with 71 and Wymspen here. You've been told repeatedly that the answers to much of your questions are, "yes it's thereotically possible" because with something as complex as what you're asking about, you can't rule out some real strange stuff happening. However the probability is very low. For some of your scenarios, probably so low that as also pointed out before, it's questionable why you would worry about them when you could theoretically have other strange stuff such as the surgeon impregnating themselves (if female) or someone else somehow or other fantastical scenarios.

Wouldn't a surgeon impregnating herself be impossible considering that one doesn't actually have mature sperm in one's testicles, though? Futurist110 (talk) 06:46, 27 June 2016 (UTC)

You still don't seem to get it. When you're talking about exceptionally low probabilities and complicated biology, nothing should be see said to be impossible. And who said anything about the sperm coming from the testicles anyway? Why are you ignoring the other possibilities like sperm present on the penis or the million and one different other scenarios you can come up with? Nil Einne (talk) 13:22, 27 June 2016 (UTC)

I don't think you can ever hope to have enough info to actually calculate probabilities for many scenarios but logic would suggest some of them are more likely, particularly when combined. I believe you're past puberty, so remember it's theoretically possible you already have a child somehow that you don't know about. (Actually I think this was mentioned before too.) I'm fairly sure that both 71's and Vespine's points on insurance have also arisen before. And I aslo believe it's been pointed out that many failure rates include cases where proper advice wasn't followed by the patient (e.g. on refraining from sexual intercourse and followups) or non pregnancy related failures (detected in the followups) so you should use caution when reading failure rates.

The problem is, though, that apparently unlike many other body parts, the vas deferens--or at least its epithelium--certainly appears to be capable of regenerating and of growing back. Futurist110 (talk) 06:46, 27 June 2016 (UTC)

Sure but you're not just talking about it growing back, but it attaching to an extra testicle and this system (including the testicle) actually functioning sufficiently to result in impregnation. Nil Einne (talk) 13:22, 27 June 2016 (UTC)

Notably, on 71's points, you'll probably find it easy to convince a doctor to do semi-regular checks (i.e. after those normally recommended) to attempt to detect failure than you ever will for an elective orchietomy

The thing is, though, that a doctor certainly isn't going to pay all of my child support for 18+ years for me in the event of a vasectomy failure! Thus, this doctor should certainly stop whining and complaining and instead become willing to perform an elective orchiectomy on me. After all, the only acceptable alternative to this for me is getting an extremely dangerous "back-alley" orchiectomy (in place of a safe orchiectomy). Futurist110 (talk) 06:46, 27 June 2016 (UTC)

You're missing two key points. One is that doctors are bound by medical ethics, not what some random person thinks. Two is that as already explained what the doctor is and isn't willing to pay for is also irrelevant. Your back-alley orchiectomy isn't going to prevent pregnancy, Perhaps your back-alley orchietomy actually has a greater chance of resulting in pregnancy. Who knows?

Also you keep bringing up child support. I initially thought you had some sort of phisophical objection to fathering a child based on things you've said in the past. I'm not sure if you're hanging out in men's rights sites too much or something, but if this is all about money, and your userpage suggests you live in the US, have you considered the possibility that tomorrow you may somehow cause an injury to someone which will result in you having to pay a similar amount for the rest of that person's life which may be longer then the 18 years normal for child support? (E.g. you're too busying fretting about getting someone pregnant that you walk into a ladder and cause a serious spinal injury.) Or the possibility that something which happens during whatever operation could result in something (not pregnancy) which will again similar end up with you winding up with a similar financial burden? Or that these questions may somehow wind up with you incurring such a financial burden?

And maybe I shouldn't say this since I actually agree with Wnt that you're skirting very close to the line here (although not sure it's advice from a surgeon you need), but have you considered that having sex, as with many many things, has many risks of varying probablities besides pregnancy. And that some of these risks would result in a financial burden which in some cases would match child support? And why are you so worried about a financial burden when there are risks, some vastly more likely than some of the stuff you've suggested, of you dying? You're not going to keep your money when you die.

Nil Einne (talk) 13:42, 27 June 2016 (UTC)

and if you're really so concerned, a vasectomy doesn't have to be "or". Nil Einne (talk) 06:12, 27 June 2016 (UTC)

What exactly do you mean by "or" here? After all, even 2+ forms of birth control can simultaneously fail! Futurist110 (talk) 06:46, 27 June 2016 (UTC)

Yes, but as I said when you are talking about exceptionally unlikely probabilities, you need to consider that you could already be a father and that even death and the burning of your body isn't going to rule out the possibility you somehow becoming a father in the future and the millions of other such scenarios. Have you even researched vasectomy failures rates considering the points outlined? What about failures rates of properly used birth control (say condoms + birth control pills used consistently etc)? What about failure rates of tubal ligation? Have you tried to combine these failure rates (bearing in mind their failures should be mostly independent)? Nil Einne (talk) 13:37, 27 June 2016 (UTC)

If you are that worried about the possibility of fathering a child, just don't have sex. That is a 100% guaranteed form of birth control. Wymspen (talk) 07:21, 27 June 2016 (UTC)

According to this well-documented case study chastity is not a 100% guarantee. --Cookatoo.ergo.ZooM (talk) 10:16, 27 June 2016 (UTC)

More seriously, I strongly disagree as already outlined above. The problem is the OP is talking about exceptionally low probabilities in some cases. So low, that the possibility of pregnancy without sex shouldn't be ruled out. For example as I said above, the OP is past puberty. Even without masturbation (and sex), they've surely released sperm. The possibility that one of these could or will somehow impregnate/d someone must surely be very low, especially without intentional action, however it can't be ruled out anymore than some of the other fantastical scenarios the OP has came up with at various times. More likely, although you could say male rape involves having sex, it's not something the OP may ultimately have control over and frankly the probability seems more likely than even the OP's scenario here. In fact the possibility it's already happened and the OP doesn't know may by itself be more likely. Nil Einne (talk) 14:09, 27 June 2016 (UTC)

This has gone off the rails into personal medical advice. It's one thing to speculate about these things in the abstract, but if you want to make decisions about your vas deferans you need to talk to people who have your medical history and situation in front of them. Wnt (talk) 10:43, 27 June 2016 (UTC)

I agree the OP should seek help, but I'm not sure if it's help from someone who specialises in male reproduction. Nil Einne (talk) 13:37, 27 June 2016 (UTC)

Also we should note that child support does not necessarily end after 18 years. In some states, it is 21; in some, college costs must be paid; in some, disabled children must be supported in adulthood.[16] Rmhermen (talk) 22:19, 27 June 2016 (UTC)

June 27

N-channel MOSFETs vs P-channel MOSFETs

Modified for readability 2606:A000:4C0C:E200:C915:F679:15DB:E494 (talk) 18:05, 27 June 2016 (UTC)

I remember learning that for general switching applications, always use N-channel MOSFETs, since they’re cheaper, more common and have less R_DS(on) than their P-channel counter parts. Basically P-channel MOSFETs are for complementary pairs and niche applications only; for everything else, there's N-channel.

And yet today I came across this document[17]:

   When using an N-channel MOSFET in a load switch circuit, the drain is connected directly to the input voltage rail and the source is connected to the load.

BIG diagram
I've always connected the drain to the load and the source to the ground, like this: .

   The P-channel MOSFET has a distinct advantage over the N-channel MOSFET, and that is in the simplicity of the on/off control block. The N-channel load switch requires an additional voltage rail for the gate; the P-channel load switch does not. 

I have no idea what this is about. Why does the N-channel load switch requires an additional voltage rail? Using TTL logic is plenty enough to drive the gate high with respect to the ground. Johnson&Johnson&Son (talk) 12:36, 27 June 2016 (UTC)

The data sheet considers only Common drain configuration of a load switch transistor so your Common source circuit (which inverts the gate control signal) is not considered. It also does not limit applications to those where standard TTL 5-volt supplies are available. The switch-off time of your circuit drawn is prolonged by the Miller effect, see Common source#Bandwidth and the supply voltage must not exceed the transistor's V_GSmax. AllBestFaith (talk) 13:56, 27 June 2016 (UTC)

The quoted paragraph basically says to use the transistor as a high-side switch (transistor on top of load on the diagram.) Naturally, as there's now something between source and ground, and it drops voltage (ideally most of it), source is positive wrt ground and you'll need a second voltage to make the gate more positive still, by at least Vth. I don't know what the advantage of using an N-channel type as a high-side switch is, one obvious one (in addition to what AllBestFaith said about bandwidth) might be that the load's ground is the same as the circuit's (no Rds in between.) Asmrulz (talk) 15:47, 27 June 2016 (UTC)

Ok, I think I get it now. That datasheet is dealing with a very specific case then. I guess I was mislead by its very board title of "Using MOSFETs in Load Switch Applications" and thought it was talking about using MOSFETs as load switches in general.

So let's a take a simple example, using a CMOS logic level output of a microcontroller to drive a LED. The bandwidth doesn't matter. Free choice between Common drain and Common source since the gate drive is under our control. Free choice between high side drive and low side drive since the LED doesn't care about being on the ground or not.

In this case, would the right choice be a N-channel MOSFET or a P-channel MOSFET? Johnson&Johnson&Son (talk) 18:39, 27 June 2016 (UTC)

I'd personally say that in this case it doesn't even matter if it's a FET or BJT, nevermind its type of conductivity. But N-channel types tend to be "better." For example, the IRF540 has a smaller Rds(on), smaller rise and fall times, a higher ampacity and is also cheaper than its P-channel complement IRF9540. Sometimes the N-channel will even have a smaller Vth (absolute value) Asmrulz (talk) 20:34, 27 June 2016 (UTC)

Visibility of a nebula from nearby

As I understand it, the Orion Nebula takes up basically a degree of the sky (24/1344 * 360/2pi) or 60+ arc minutes, and therefore is twice the size of the full Moon. But only people with very good eyesight even notice it. I assume it would be no brighter from nearby, and this backs me up. However, maybe the middle is more visible, or maybe other nebulae are more visible.

The Earth has been wandering around the galaxy for (almost) five billion years and had a lot of chances to wander close to such events. What I'm wondering is -- what is the brightest that this has ever made the night sky? Has it ever been equal to a permanent moonlight or more? I imagine someone somewhere must have run simulations, so I thought I might as well ask.

If people can back up the source above as true, I should also probably put something about it high up in Nebula so people understand that you don't have planets where you just look out and ooh and aah at the beautiful colors. Wnt (talk) 15:54, 27 June 2016 (UTC)

Your source says

Yes, if you get closer, your eye will receive more total power from the nebula. But the nebula will also look bigger, so that energy will be spread out over a larger visual area (technically: “solid angle”). The physics tells you that the power per solid angle in fact stays exactly the same, and this quantity is precisely the “brightness” of an object. So if nebula are too faint for to see from Earth with the naked eye — and they are — getting up close and personal doesn’t help any.

While the source says this is a paraphrasal of an astronomer's email, I fing it perplexing. Suppose you apply the same reasoning to a star that is invisible from Earth to the naked eye, instead of a nebula. If we got closer (say 1AU from the star) would it really still be invisible? What am I missing here? Loraof (talk) 16:18, 27 June 2016 (UTC)

It is true so long as the image is on a significant part of your retina. However, once it gets down to a single cell being lit up (if you have perfect vision) or to whatever point that a blurry image gets dimmer rather than smaller, then it gets dimmer instead.

It is also not true for very bright light - the Sun on a normal day is less bright than a sliver of sunlight seen during an eclipse, because the iris clamps down on sunlight but might not react properly to just a small searing point on the retina. Wnt (talk) 16:26, 27 June 2016 (UTC)

The source is correct. If you have very good eyesight and you're at a very dark place, you may be able to see such a nebula with your naked eye. As light pollution has increased dramatically in the past 25 years, I doubt anyone can still see those nebulae with the naked eye from my small Western-European country.

Nebulae (not including the galaxies, some of which are still called nebula because they were discovered and named before the difference was known) work by scattering starlight. So, if you're inside one, it will at best be as bright as a piece of paper you hold in your hand (maybe a little more, taking fluorescence into account). If you're some distance away from a star, that's quite dim. Moreover, nebulae consist of a mixture of dark dust and gas that only scatters very specific wavelengths. So that would be a dark, coloured piece of paper. Now you could of course imagine you're very close to a bright star sitting in that nebula, but stars have the habit of using their wind to blow a hole in the nebula. If the Sun were in a nebula, the nebula would only begin at the heliopause, which is so far away that it's quite dark there. PiusImpavidus (talk) 19:50, 27 June 2016 (UTC)

I agree with what's been said, above - but take a more practical example: The Milky Way galaxy shines with the light of maybe 200 billion suns - an unimaginable amount of light - and yet, here we are, out on the very edge of it (you really couldn't get any closer!) - and yet we can only just barely see it at all with dark, clear skies as a softly glowing smudge. The exact same thing would happen with a nebula if you got up close to it. SteveBaker (talk) 20:23, 27 June 2016 (UTC)

Nitpick: we're not at the edge of the Milky Way. We're about halfway out from the galactic center (I've heard it put that we're "in the suburbs"). --71.110.8.102 (talk) 22:33, 27 June 2016 (UTC)

While I agree with the answers given so far, one has to note that M44 is a very bright object. Only if there is extremely severe light pollution where you live will it be hard to spot. You probably have something like Bortle class 8 skies: "City sky. The sky glows whitish gray or orangish, and you can read newspaper headlines without difficulty. M31 and M44 may be barely glimpsed by an experienced observer on good nights, and only the bright Messier objects are detectable with a modest-size telescope. Some of the stars making up the familiar constellation patterns are difficult to see or are absent entirely. The naked eye can pick out stars down to magnitude 4.5 at best, if you know just where to look, and the stellar limit for a 32-cm reflector is little better than magnitude 13."

Without light pollution you're at Bortle class 1: "Excellent dark-sky site. The zodiacal light, gegenschein, and zodiacal band (S&T: October 2000, page 116) are all visible — the zodiacal light to a striking degree, and the zodiacal band spanning the entire sky. Even with direct vision, the galaxy M33 is an obvious naked-eye object. The Scorpius and Sagittarius region of the Milky Way casts obvious diffuse shadows on the ground. To the unaided eye the limiting magnitude is 7.6 to 8.0 (with effort); the presence of Jupiter or Venus in the sky seems to degrade dark adaptation. Airglow (a very faint, naturally occurring glow most evident within about 15° of the horizon) is readily apparent."

What you need good eyesight for is not M44 but M81 see here for Brian Skiff's account of how he spotted this with the naked eye. Even Neptune is in theory visible to the naked eye, it's just that only a few people have made a serious attempt to spot it, Brian Skiff tried but failed, he was observing from too far North, Neptune is then difficult to spot due to being too low in the sky.

If you compare these facts to what reliable sources have to say about what is visible or not to the naked eye, so see just how much severe light pollution is assumed as the normal viewing conditions. Count Iblis (talk) 21:23, 27 June 2016 (UTC)

Are SpaceX's rocket and/or engine designs certified by licensed P.E.s?

75.75.42.89 (talk) 22:39, 27 June 2016 (UTC)