Wikipedia:Reference desk/Archives/Miscellaneous/2014 August 18

= August 18 =

Putting someone to sleep with a healing Superpower
My character in a roleplay has the power to heal people of their wounds. By extension, he has the power to do the opposite; accelerate cancer cells, prevent blood from clotting, and pinch off a blood vessel until part of the brain dies. However, he's very kindhearted and doesn't want to do any of that lethal stuff. I'm just wondering what some believable ways there are for this character to use his power just to put people to sleep, or at worse knock them out. Nothing that causes longterm harm (or ideally, short term harm). 98.27.241.101 (talk) 02:54, 18 August 2014 (UTC)
 * Something like the Vulcan nerve pinch? According to our article (but unsourced):  "... the ability to project telepathic energy from their fingertips ... which if applied to a nerve cluster correctly could render a human unconscious."  — 71.20.250.51 (talk) 06:09, 18 August 2014 (UTC)
 * Can your character "remove fear"?
 * From that, it wouldn't be much of a stretch that he can stop panic and calm other characters down, and maybe extend that to induce sleepiness. However, that would take a lot of time and couldn't work as fast as Spock's nerve pinch, and probably requires that the character remains unspotted through the whole trick. - ¡Ouch! (hurt me / more pain) 07:00, 18 August 2014 (UTC)


 * A little hypoxia is relatively (to poison or clubs) harmless. When it's fatal, it's relatively (to arrows and fire magic) painless. If you're a really white mage, you may want to transfer some oxygen (and Speed, Intelligence, Dexterity, whichever) from an enemy to an ally. Waste not, want not. Temporarily, of course. InedibleHulk (talk) 21:46, 18 August 2014 (UTC)


 * Judging by your character's abilities (being able to control cell activity it appears), I don't think it would be a stretch to believe this character can control cell activity in general. In that case, I would think your character could induce relevant hormonal release (melatonin and the like) and induce sleep-related neural patterns by manipulating neurons. That or the character could act like many hypnotic drugs and target the person's GABA receptors. Inducing brief hypoxia as mentioned above would probably work as well. Plenty of ways, assuming your character has this level of control over bodily functions.  Bramble claw  x  14:13, 19 August 2014 (UTC)
 * According to Strangling, "Incomplete occlusion of the carotid arteries is expected and, in cases of homicide, the victim may struggle for a period of time, with unconsciousness typically occurring in 10 to 15 seconds." So, just a brief pinching of the carotid arteries should be fine to justify this. uhhlive (talk) 21:15, 19 August 2014 (UTC)
 * See also Choke hold. It is quite reliable if used properly. Its use, even by trained personnel, is restricted now; even a low risk of permanent damage can be quite severe, even more so with multi-million dollar lawsuits. - ¡Ouch! (hurt me / more pain) 08:38, 20 August 2014 (UTC)
 * See also choking game. Dismas |(talk) 10:21, 20 August 2014 (UTC)

Ship maneuvers during a beach landing
I just finished watching Flags of Our Fathers and took this screenshot during the film. For those who haven't seen the movie, it's about the flag raising at Iwo Jima. What I'm wondering is what those boats are doing going in circular patterns. Can anyone explain that to me? Thanks, Dismas |(talk) 06:33, 18 August 2014 (UTC)
 * It is the same technique when launching a formation from an aircraft carrier. Each craft can only be launched one-at-a-time, yet they need to be in formation for the mission.  This method prevents them from bunching up; also allows everyone to begin assault at the same speed; otherwise, the folks at the back would have to wait for the ones in front to start moving before they could begin.  This way, they can all move at the same time with the same speed.  Also, the "circles" become larger as individual landing craft are added; this is simpler than trying to arrange rows & columns.  One doesn't need to figure out which row and/or column to go to; one simply joins a circle.  — Sorry that I don't have time to find sources. ~:71.20.250.51 (talk) 07:06, 18 August 2014 (UTC) 
 * An unanchored, non-powered boat, in a sea-swell, will tend to turn side-onto the waves. It will then start to rock with the waves, and can capsize. For this reason, in mass-start sail-boat races, the crew will have their boats turning in circles just before (the very long) start line. CS Miller (talk) 09:07, 18 August 2014 (UTC)


 * I had a look for a reference to back up these explanations and found lots of accounts of landing craft circling, but only one which attempts to explain it, thus: "In the middle foreground are some LCVP's moving in a circle. This maneuver is performed until all the craft are assembled and are given the signal to move up to the line for the final dash in." CS Miller's point above about the need to keep headway in a swell explains why they don't just wait "dead in the water". Alansplodge (talk) 12:24, 18 August 2014 (UTC)

Thank you for the responses, everyone! My own theory for why they would want to keep moving was so that the guns on the shore would have a harder time hitting the boats. Thanks again, Dismas |(talk) 00:21, 19 August 2014 (UTC)

Vector analysis of course(s) taken by a nation
I have seen vectors (positive and negative in direction <---|--> = <-|} used to describe and explain single-issue choices made by the people of a community such as a nation. It should, then, be possible to plot a large number of single-issue vectors and attempt to account for the general course that the community/nation is taking. For one thing, researchers would have to identify the relevant motivations/forces that determine complex decisions And there would be technical difficulties with the calculations if vector pairs were cross-linked with other vector pairs.

This is the way I was taught to think about political decisions, but I want to find an academic source or sources that I can link to.

Thanks. P0M (talk) 19:49, 18 August 2014 (UTC)


 * Interesting. What you describe is a game mechanic in the Europa Universalis series by Paradox Interactive, along with many of its other games.  You use "sliders" to alter your nations political landscape (similar to the vectors you describe) and your get certain benefits or penalties based on your political decisions.  Your strategy depends on how you choose to set your "sliders".  -- Jayron  32  21:29, 18 August 2014 (UTC)


 * There is an "ant-learning" function implied in the way a 1950s politician explained it to me, or you could say it is like the experiments where many people try to guess the number of beans in a large glass container. Individually, nobody may get particularly close, but the average of all guesses is a good estimate of the true number. So at one time crime may be way out of control and so many people are recruited to the "lock 'em in jail and throw the key away" school. Prison sentences become more and more extreme and gradually more and more people get recruited to the "get them to repent, reform, and then release" side of the balance. Things can't go too far in any direction because individual humans are pretty accurate observers of their own condition, so if a large number get sick of some social condition their attitude will show up in the change of the appropriate vector.P0M (talk) 04:22, 19 August 2014 (UTC)


 * How does that theory apply in a place like North Korea? ←Baseball Bugs What's up, Doc? carrots→ 07:08, 19 August 2014 (UTC)


 * Scott E. Page introduced a "Wisdom of the crowd" diversity prediction theorem: "The squared error of the collective prediction equals the average squared error minus the predictive diversity". North Korea's Ten Principles for the Establishment of a Monolithic Ideological System replaces diversity by the principle of unconditional obedience in carrying out the Great Leader comrade Kim Il-sung's instructions. Thereby the thesis of The Wisdom of Crowds, namely that independently deciding individuals will make better decisions collectively than a single expert, is overturned in NK's Juche absolutism that calls on the working class not to think for themselves, but instead to think through the "Great Leader". 84.209.89.214 (talk) 14:04, 19 August 2014 (UTC)


 * Good point, Basebaall Bugs! It gets at the more basic problem I have been working on, how to try to manage situations like Iraq in which there may be no leadership candidates when a Saddam Hussein gets taken out because the system has been constrained for so long. Imagine what it would be like if the core government of N. Korea disappeared overnight. There would be utter chaos, refugees would stream into China, creating huge problems for them, and any leaders emerging in N. Korea would have had only the role models of the Kim dynasty to base their own attempts to govern on. I would wish for a Korean Nelson Mandela to appear, but the chances would be pretty slim.


 * According to a vector model only an opposing force can counteract an emerging force that somebody who wants control has decided to repress. It is one of the primary ideas of Daoism that in such situations, what doesn't come out straight will come out sidewise. In other words, if you screw a cap on the end of a garden hose to stop outflow and then you keep increasing the pump pressure on the other end, the weakest point in the hose will break and water will start coming out. When the U.S. instituted Prohibition, many people still wanted to drink. So bootlegging, bathtub gin production, basement wine production, etc. etc. proliferated, and in addition those "streams" influenced other vectors pertaining to things like organized crime, smuggling, etc.


 * Metal springs expand when heated. To stop a spring from expanding you could put it in a heavy C-clamp. If spring pressure mounts up to the point that the constraint device fails, then the potential energy stored up in the spring will be released explosively as kinetic energy, and you wouldn't want to be along the trajectory of the broken clamp parts.


 * In North Korea, every natural impulse must be being opposed by applications of brute force. It would be a fascinating study to work out how a ruler can recruit coercive force from his subordinates and use that force to control those subordinates and, through them, to control successive lower levels in the hierarchy all the way down to babies in the womb. The latest "dear leader" gave one demonstration of maintaining the power of the ruler when he had his own uncle (?) dragged off to be executed. P0M (talk) 16:37, 19 August 2014 (UTC)
 * Uncle by marriage, iirc. —Tamfang (talk) 04:51, 20 August 2014 (UTC)


 * The question reminds me of various attempts to reduce the universe of political opinions to a small number of dimensions by measuring the correlations between (e.g.) votes in a legislature or answers to a questionnaire. —Tamfang (talk) 04:51, 20 August 2014 (UTC)


 * It's probably a little like predicting weather by characterizing equal-sized volumes of the atmosphere, the more closely you dice up the atmosphere, the more difficult the math becomes. The more "dimensions" there are, the more complex the math. On top of everything else, like the weather, there is a sort of cross-linking of dimensions, i.e., changing something going on in one dimension can "drag" something going on in another dimension. Questionnaires that show the tolerance for violence of members of a population may change from time to time, and questionnaires that show the prevalence of childhood abuse may also change from time to time. Then you find out that if something happens to increase tolerance for violence (a long war for instance) the other questionnaires show a growing tendency toward child abuse. Or if something happens to increase child abuse (some kind of propaganda attack involving psychobabble perhaps), the tolerance for violence measures may go up. The tricky part of the math (if the analogy to weather prediction holds, for instance) is that a tiny change in one measure in one direction can result in a major change in another measure a little while down the road.


 * I'm out of my depth when it comes to discussing this stuff on a firm mathematical basis, and it may seem irrelevant to others if no professionals in the field happen to use this kind of approach. So I'd like to know if there is a formal treatment of this stuff somewhere.P0M (talk) 05:25, 20 August 2014 (UTC)

When do you need to sign when using credit card?
In North America, when using my Visa credit card, sometimes the cashier asks me to sign the receipt and sometimes I am not asked to sign. Why is there this inconsistency? Acceptable (talk) 21:50, 18 August 2014 (UTC)


 * I know it's not what the question is asking, but since the beginning of this month in Australia we have not been allowed to sign. HiLo48 (talk) 22:00, 18 August 2014 (UTC)
 * Not allowed to sign? Why? ←Baseball Bugs What's up, Doc? carrots→ 22:53, 18 August 2014 (UTC)
 * Switching over to PIN verification only. See Sign-off looms for credit card signatures (The Sydney Morning Herald). -- ToE 00:39, 19 August 2014 (UTC)


 * My experience is that, at most points of sale, there is a threshold amount; if the transaction is above that, you will be asked to sign; if below, you will not. Usually it's 25 or 50 dollars.  But it depends on the retailer; some will always ask you to sign (especially in an eating or drinking establishment, when there's a line for tips).  On the other hand, for gasoline, there's generally not even an option to sign. --Trovatore (talk) 22:08, 18 August 2014 (UTC)
 * Gas pumps often ask for some vital info, typically your zip code which I assume is embedded on the card's mag strip. ←Baseball Bugs What's up, Doc? carrots→ 22:53, 18 August 2014 (UTC)
 * Yes, because after all, people who want to buy gas but don't live in the US and therefore don't have a ZIP code are of no importance whatever. Sigh. --50.100.184.117 (talk)
 * You can always go inside the store to charge the purchase, or - gasp - pay in cash. ←Baseball Bugs What's up, Doc? carrots→ 07:01, 19 August 2014 (UTC)
 * Yes, and line up to do it. Twice, if I want to fill the tank, because these days the stations all require prepayment and if I'm filling it up I need change.  And if I use a credit card inside, they still want a prepayment: say I prepay $50 and the fillup costs $38 so I get $12 back, then several percent of the $12 goes to the bank as they don't offer the same currency exchange rate for reverse transactions.  None of this a big deal, of course, but it is an annoyance to be treated as a second-class customer. --50.100.184.117 (talk)  — Preceding undated comment added 07:53, 19 August 2014 (UTC)


 * I'm having trouble finding anything due to recent changes to some state laws about minimum purchases with credit cards. Here in Canada at least, signing is being phased out; I don't believe I've signed anything in more than a year and I buy everything on M/C. For cheaper transactions, no verification is needed at all, though I don't know if that minimum is set by the retailer or the card company. Above that threshold, we need to insert the chip on the side of our card and enter a PIN. That's perhaps what HiLo was referring to regarding not being able to sign; it's sure not an option for me. Matt Deres (talk) 23:46, 18 August 2014 (UTC)


 * Yes, that's the way it is now in Australia. Just the card for many small transactions, card plus pin for larger ones. No option to sign at all for any transactions. I have wondered what will happen next time I visit the US and am expected to tip everywhere. HiLo48 (talk) 00:52, 19 August 2014 (UTC)
 * There were apparently issues for a lot of Americans at the recent soccer World Cup who had cards without a chip and a PIN. Hack (talk) 02:55, 19 August 2014 (UTC)
 * The relevant articles about this are at Chip and PIN, Smart card, and the links therein, but we're drifting further from the OP's question. Matt Deres (talk) 03:13, 19 August 2014 (UTC)

I live in the U.S. A few years ago I went into a fast-food shop and bought my lunch, expecting to have to input the PIN for my debit card. However, I just got a receipt. There is a limit, probably set by each merchant, below which they don't want to be bothered with the details. If a stolen credit card is used, the true owner of the card won't be charged, so either the bank or the merchant has to take the risk. Above the limit, the merchants that use this method will require a signature or a PIN. As far as I know, nobody announced this change. Procedures were simply changed. For a long time the card-reader devices on gasoline pumps did not require any signature or equivalent. A few years ago some started asking for the postal code for my billing address, and others started requiring the PIN for my debit card. P0M (talk) 04:04, 19 August 2014 (UTC)
 * I live in Austria. My credit card is signature-only, no PIN.  I always have to sign. --Viennese Waltz 07:48, 19 August 2014 (UTC)


 * Banks charge different amounts for credit card transactions based on differing factors. They assume that transactions without signatures are more likely to be fraudulent, so prefer higher amounts (say, over $15) to be accompanied by a signature.
 * For example, X Bank may charge companies 1% for all transactions accompanied by signatures because they are low risk; they may charge 3% for all transactions without signatures below $15 because they are higher risk, but not such a financial burden if fraudulent; they may charge 5% for all transactions without signatures over $15 because they are higher risk and more of a financial burden if fraudulent.
 * Companies such as Subway, KFC etc take on this higher cost for unsigned transactions because their business model means they need to deal with customers quickly. So, whilst they may by a little more to the Bank, they don't have to take the time to ask for signatures and can get through more customers' orders.
 * Here in the UK, all cards are chip and pin, so we never have to sign for a transaction.Sotakeit (talk) 12:57, 19 August 2014 (UTC)
 * On pumping gas/petrol in foreign countries: I always use cash because I get a better exchange rate on ATM transactions than on credit-card transactions. I suggest that approach for people visiting the United States.  Yes, you will generally have to queue/stand in line twice, but usually the wait isn't so long in those places.  (There are still remote rural parts of the United States where they trust you to pay after pumping.) Marco polo (talk) 18:36, 19 August 2014 (UTC)
 * I'll still have no idea how much to tip and, because shelf prices aren't tax inclusive as they are elsewhere, how much I will have to pay. I love visiting the USA, but financial transactions there annoy the crap out of me. HiLo48 (talk) 21:18, 19 August 2014 (UTC)
 * Your problem, HiLo is that you don't realize you are visiting 50 sovereign states, not one. Next time you vistit go to a stste without sales tax or don't complain--it's not like you've been kidnapped.  Tipping 15% excluding any tax is standard.  Round up if the service is good, rodund down if it's poor. μηδείς (talk) 21:35, 19 August 2014 (UTC)
 * Your problem, Medeis, is that you don't realise that my country also comprises six sovereign states (and two territories) but we've had the sense to legislate that shelf prices reflect cash register prices. It's not all that difficult to achieve. And tipping is still a mystery. Do I tip at petrol stations? Train stations? Bus drivers? Don't answer. My questions just highlight the mysteries. HiLo48 (talk) 22:15, 19 August 2014 (UTC)
 * Yes, and the reason for those difference is that they exist. It isn't necessary to consider one's own personal situation as normative.  Australia and the U.S. (just to pick two countries at random) have different traditions regarding pricing and payments, and neither is better merely because one has grown up in one system or the other.  They are different, and they can just be different, without having to defend the one, or denigrate the other.  -- Jayron  32  22:18, 19 August 2014 (UTC)
 * I think I can defend a system of shelf pricing against one that makes no comparative sense, and would be very easy to change if people and legislators actually cared. I understand the difference in tipping being a cultural thing, but I retain my right to admit massive confusion, and a constant feeling of guilt that I will get it wrong, and either rip someone off, or tip inappropriately and offend. And, getting back to the topic of credit cards, tipping with cards, especially now we can't sign with our cards in Australia, will only be more messy. HiLo48 (talk) 22:42, 19 August 2014 (UTC)
 * At the risk of getting even farther off topic, how would not signing make it more messy? If you're entering a PIN, can't you also enter a tip percentage or amount?  Dismas |(talk) 00:18, 20 August 2014 (UTC)
 * If I buy a small item such as a coffee, I just wave my card at the machine and off I go. No PIN required. No mechanism for tipping. HiLo48 (talk) 01:21, 20 August 2014 (UTC)
 * Ah! For small purchases. Got it.  I was thinking about meals where you'd have a larger bill.  Dismas |(talk) 01:30, 20 August 2014 (UTC)
 * There's no fixed rule, but I've experienced "no pin" for amounts up to $100. HiLo48 (talk) 03:12, 20 August 2014 (UTC)
 * If you're talking about Contactless payment, according to our article actually AU$100 is the maximum allowed by the credit card companies in Australia so there is a fixed rule. (It varies from country to country, here in NZ it's NZ$80.) It's possible some companies may choose to impose additional limits (I think this is possible but I'm not sure). Note that there are often also additional security measures such as requiring a PIN after a set number of contactless payments (to reduce fraud in the case of a loss or stolen card). Nil Einne (talk) 14:37, 20 August 2014 (UTC)
 * Regarding tipping on card, in the UK, it's only really chip and pin machines at restaurants that give you the option to leave a tip. Anywhere else (hotels, taxis, stores, fast food establishments etc) the machine doesn't allow you to, so if for any reason you want to tip you'd have to do it in cash after the card payment. Sotakeit (talk) 08:30, 20 August 2014 (UTC)


 * Having recently gotten interested in this and also gotten in to a minor edit war at EMV, I can say that it's actually more complicated than pin or signature. You can actually have offline PIN verification or online PIN verification rather than simply PIN. While this may be largely transparent to the end user it can mean differences in acceptance.
 * For example, online PIN is the number here in NZ (as I think Australia) and has been since long before chipped cards arrived here. In the case of my specific credit card, I don't believe it even supports offline PIN verification by default or at least in some case. I say this because it's possible to set up the PIN without visiting the bank at all, solely by doing it over the internet on my online account (2FA is required).
 * It's possible that the offline PIN is set by online POS terminals, but for security reasons, I find this unlikely. So more likely, my current card has no offline PIN set up. I may be able to set it up in the bank (I had trouble finding any info on this though). Unsurprisingly, I have heard of people who've visited countries where the PIN is used who've found they needed to sign, I presume these may be terminals where offline PIN is used, or alternatively the online PIN couldn't be verified.
 * As hinted in our EMV article, even that is an over simplification as there can be cases where you need both the PIN and signature. IIRC I had that experience in Malaysia at times. From the discussion above, it sounds like some are using the Address Verification System instead of PIN in the US.
 * Basically as I understand our EMV article, the credit card itself has a list of cardholder verification methods that are allowed by the card in order of preference. The terminals similarly have a list of cardholder verification methods that they allow (possibly without preference but I'm not sure). The terminal queries the card and chooses what CWM method is suitable based on the respective lists and any additional flags (e.g. transaction amount and I wonder if some have additional flags for what they consider high risk transactions).
 * Nil Einne (talk) 14:37, 20 August 2014 (UTC)

It does not seem as if the question has truly been answered here. The question was why do people have to sign for some purchases and some do not. The reasoning are more than just one. Some banks and companies require signatures over a certain amount mostly all be $25. $25 is the set amount that anyone can take to civil court, anything less can and will not be tried in court. Think about the amount of money a company can lose if they had a stole credit card used in their store and they did not ask for a signature to trace back to the person that used the card. I live currently in the UK, and for any purchase your signature is required or the signature on the card is checked to your ID. That might seem over the top to an American but it is only for your protection.