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When is it OK to "Stop" for a school bus? | Unless there is a median between you and the bus, you must stop. In many places, school buses can't/don't stop on a road with more than 4(?) lanes, so multilane cases just don't show up | Seat belts in buses aren't actually safer. In an emergency, it's a lot easier to get 3-4 people out of a car when they're buckled, but much harder to get 60 children out of a bus when they're buckled. Not to mention that kids are little shits, so they'll hit each other with buckles and the driver can't really guarantee that they're buckled in the first place. (Edit - Actually, they can guarantee it in the first place, i.e. before they start driving, but they've got no way of guaranteeing that the kids won't just unbuckle as soon as the bus starts moving) School buses are a pretty safe form of transportation since most other drivers are unlikely to mess with them, and due to their size they are less likely to tip over. _URL_0_ |
Saw this ring around the moon tonight, what is it? | It is a [lunar halo](_URL_0_), caused by refraction of moonlight through high altitude ice crystals. They are a tad more rare than solar halos because the moon needs to be near full to be bright enough to create them. | What you're seeing isn't a ring of clouds. It's moonlight being reflected and refracted by tiny ice crystals in the upper atmosphere. It's called a [22° halo](_URL_0_), because the hexagon shape of the ice crystals cause the halo to appear 22° away from the source of light. |
If you have food allergies, are there any that make you ineligible for organ donation? | Yes, potentially. We have seen both tree nut and peanut allergy transmitted from donor to recipient in solid organ transplants (lung, liver). This is due to the passage of long lived tissue resident plasma cells which continue to produce antibody to these allergens. It would not exclude a donor by itself, but is a consideration when accepting a donor. We now know that there are situations in which donor immune cells can persist for long times, sometimes forever in the new recipient instead of being killed by the recipient's immune system. That's cool. | Multiple things can happen: 1. The body can immediate reject the organ because of a blood type mismatch, this is called hyperacute rejection. 2. The body can live with the organ for a little while, but then via one of two (very similar) methods, the body mounts a cell mediated immune response where host cells attack the organ. This is called acute rejection 3. The body lives with the organ for years and suddenly finds an antigen and makes antibodies against it. The body then kills the organ through various antibody mediated processes. This is called chronic rejection. These all occur because the body recognizes some protein in the organ that does not exactly match the host body, and it does not always occur because some matches are better than others, and organ donation recipients receive immunosuppressant drugs (except in the case of a few very special transplants, only two I can name off the top of my head) to prevent rejection. |
How much of the human genome have we identified and understand? | You can have a look yourself: _URL_0_ You can see the genes on top and various other functional dataset bellow. If you mouse over the tracks on the left it gives you a short explanation of each one. I'd say we know a lot of things overall about the genome. | The answer depends on your definition of "know". The vast majority of proteins we have sequences for, because we have the human genome and genes mostly look a certain way. In terms of knowing what the protein does or where it is expressed, the vast minority of human proteins are characterized. I would estimate no more than 10%. |
Comparing pictures of Iran in the 60s to now makes me very sad. Can anyone provide a synopsis of how it came to occur? Any good Youtube documentaries or articles? Are there other recent examples of countries regressing like that? | I don't have any academic recommendations, but Persepolis by Marjane Sarpati is a very well written very entertaining fictional account of Iran leading up to the Islamic Revolution. It's in comic book format so its an easy read. _URL_0_ | Prior to the 1979 Islamic Revolution, Iran was one of the "Twin Pillars" (corrected) of US foriegn policy and deemed to be the "Policeman of the Persian Gulf" so Iran was the favored power and Saudi Arabia was the lesser but which benefited from Iran providing security in the region (Iran and the UK fought off a Communist insurgency in Yemen/Oman in the 1970s.) So the Saudis grumbled but recognized/were resigned to Iranian ascendancy in the region. Iran is after all a "Natural Hegemon" -- longest coastline, largest population etc. After the 1979 Islamic Revolution, the relations went bad pretty quickly as there were demonstrations in Mecca sponsored by Iran that challenged the Saudi monarchy's religious qualifications and authority. The Saudis (and Kuwaitis) were also the strongest backers of Saddam while he waged war on Iran. |
Why wasn't Venice a part of the Holy Roman Empire? | In the 8th century, the Republic of Venice had pro-Frankish, pro-Byzantine, and pro-Lombard factions during the time of Byzantine decline. Charlemagne had designs on Venice, but failed to conquer it. As a result, Charlemagne recognized Venice as Byzantine territory. Over time, as the Byzantine declined, Venice obtained special privileges (such as exemption from trade tax) and became de-facto independent. Therefore while the Kingdom of Italy based in Lombardy became part of the HRE, Venice was able to remain (de facto) independent. | Follow up: Did the structure of the Holy Roman Empire help or hinder member states going to war with other members? |
When did calling somebody "Sir" change from meaning a knight or nobility to just politeness? How did the change occur? Was "Sir" just for those who were officially knighted? | The title 'Sir/Sire' got attached to knights in the 13th c. because it had been a general politeness marker in Old English. It has the same root as French 'Seigneur' and Latin 'Senior' The use of 'Sir' as a politeness marker PRE-DATES the use of 'Sir' for a knight's title. | Because people don't use "sir" in that context in real life. It sounds like someone pretending to be from the 1920s, which comes off as pretentious. |
How do they get the footage for ocean documentaries? | There's an actual documentary of how the blue planet was made and how they shot everything. I remember that for the deep sea shooting they used a small submersible vessel and they went deep into the ocean. It was like an ocean car which was used to shoot the part in the dark. And here was light but it didn't scare the fish. And also they had high tech cameras! | _URL_1_ This massive scientific endeavor was live - streamed on multiple cams (different vessels and you could select which cam to look at) the whole time they were in the trench. I didn't follow it religiously but checked in a bit and watched some of the streams - saw some very cool stuff. They had scientists on the boat and back on the mainland who were experts in various areas that would chime in and provide their knowledge. It was seriously interesting. Should be heaps of cool photos, vids and info on the website 😀 |
Let's say I scrape up my hand. How does the skin grow back exactly the same? | Your skin is constantly shedding then regenerating itself. Cells divide in the basal layer of the epidermis, and the new cells are pushed up towards the surface of the skin, going through various changes as they do so including losing their nucelus, and when they reach the surface the are mostly just keratin and act as protection. Eventually they will be shed and the new cells being pushed up from below take their place. The whole skin takes about a month to completely regenerate. So even without wounding your skin is constantly in a process of 'growing back the same'. And even without wound healing mechanism, if you scratch your hand it will regenerate through that process. If the damage is deeper than the epidermis, than the skin will generally not grow back the same. Scarring can occur with deeper tissue damage or even with shallow damage depending on the wound. | The body needs a matrix upon which to generate. If you have a cut on your finger, then the body has a framework—the finger, to grow on. But when you amputate a body part, it has no framework upon which to build. The foreskin is gone so it’s not going to grow. However, I understand that some guys do some kind of stretching of skin to recreate a foreskin. |
Why aren't hardware volume control knobs used in consumer electronics anymore? | More of a comment here, but as a 41 year old, I am quite distressed by these touchscreens in cars instead of control knobs for stereo volume, vent air speed, etc that used to be in all vehicles. I understand the knobs probably haven't actually controlled things mechanically in a long time, but quite frankly, when I am driving it is a lot easier to grab a knob and turn it than take my eyes off the road to dink around with a touch screen to try to get something adjusted. | It depends on how complex the circuit is, but in a simple setup the knob is attached to an electrical device called a [potentiometer](_URL_0_) which is basically a resistor that changes resistance as you turn it. When there is more resistance in the circuit, the volume of the speakers is lower. |
What is MLM and why is it bad? | Multi-level marketing is a business structured around having salespeople not only sell products but also recruiting others to sell products on their behalf. The reason it's bad is that MLM schemes tend to primarily sell 'in network'. That is, the only realistic way to make money is to recruit other people to whom you sell the product. The premise is that they'll turn around and sell that product on your behalf. The reality is that such products are rarely able to be sold. As a result, the entire business ends up being little more than a pyramid scheme. | Because it actually offers real products for sale whereas, pyramid schemes do not according to the US FTC (Federal Trade Commission). Therefore, it is categorized in the MLM (multi-level marketing) organizational category, which is a legal business and not a pyramid which is illegal. Also, MLMs make money by enrolling people into their organization + selling products to those people rather than a pyramid which just makes money from enrolling people (no product to sell). The fact that MLMs are legal though baffles me as they just take advantage of lesser people by selling them false hopes and setting them up to fail and burn bridges in their personal lives. |
Globalization, positive and negative things about it. | Globalization is the idea that the world is significantly more connected than it has been in the past. Communication, as well as transit/shipping, is faster and cheaper than ever and is only getting cheaper. The general economic positive is that things as so cheap to ship companies can save a lot of money by getting their materials and/or labor from the cheapest places, thus lowering the price of goods. The negatives is that places that used to make those things go put of business because they can’t compete, mainly affecting developed nations. Personally I view it as inevitable, and smarter to economically pivot around then to try and stop. | The marvels of industrialization, a huge amount of arable land to sustain a relatively large population, and the majority of your competitors in the race towards modernity getting taken down a peg by WWI. |
Why is 1080 poison (sodium fluoroacetate) so toxic to mammals but less dangerous to other animals? | So fluoroacetate works by integrating into the citric acid cycle (Krebs cycle) by substituting for acetate to form fluorocitrate and then disrupting this key cycle by binding tightly to aconitase which prevents this critical cycle from functioning and killing the poisoned organism. It does affect birds as well although reptiles are much less susceptible. Generally birds aren't as attracted to the baits though - they are deliberately coloured to avoid birds eating them and DOC has determined quantities etc that minimise the potential bird effects. It still does effect them though - kea have a 12% mortality rate in areas that have 1080 drops but this is a significant improvement from their losses to rodents if the population explodes Good review is [here](_URL_0_)(pdf) and DOC's FAQ is [here](_URL_1_) | There is a difference between venom and poison, venom has to be injected to be dangerous (usually via a bite or sting) whereas poison just has to be injested to be dangerous (eaten or absorbed through skin). So consuming a venomous animal would generally not be as hazardous. |
Why are so many refugees suddenly heading to germany? | Germany is a large (population 80 million) and rich (GDP per capita $45,000) nation. It has good social services and is known to take in a lot of immigrants. The refugees recognize this and want to move to Germany because they see it as a secure and stable place to live. | Basically, due to the Syrian civil war nearly 11 milion people have been displaced. Many of those settled in neighboring countries like Turkey, Egypt and Libya. The problem is that those countries have become unsafe for refugees. The new Egyptian government is hostile to the refugees and is forcing them on to Libya, however in Libya the government has all but collapsed and IS is on the rise there. In Turkey there has been a wave of attacks on refugees and increased fighting by the Kurds. This is causing many refugees to flee those countries, and most are seeking the safety and stability of Europe. The problem is that Europe, seeing that these people are not fleeing from their country of origin has labelled them as migrants instead. |
Why international accents sound charming, but regional ones usually sound awful? | Most often foreigners are exposed to a more elegant upper class accent/dialect/slang. They don't get to see the working class people who use a cruder accent/dialect/slang, as often. | Same goes for the rest of Europe, lots of very distinct accents and dialects on a very small scale (EDIT: eg. from one mountain valley to the next). I think that in the former colonies the language just didn't have time to diversify that much, and now that we have nation-wide broadcasts of "standardized" language there is not so much chance to develop one. |
How do lock makers mass produce locks that can only be opened with one key? | They don't. They have a certain number of lock configurations and produce a lot of them, so the lock on your front door probably has hundreds if not thousands of twins out there that can be opened with your key and vise versa. In fact if you go to the hardware store, you will see that most lock sets have stickers with a serial number on them, and other packages will have the same serial number. If you get two packages with the same number, they can be opened by the same key. | Having someone pick your lock is almost never a legitimate concern. If someone wants to break into your house, they're not going to sit there in front of the door with a set of lock picks, looking suspicious for several minutes. They're just going to kick down the door or break a window, so they can get in and out as quickly as possible. Meanwhile, combination locks make it hard to securely give another person access. Once another person knows the combination, they can share it with zero effort. At least making copies of keys requires some small amount of work. |
When a light from a deep-sea submarine is shone on an organism in deep water where they never see light, what effect does it have on them? | [Cindy Van Dover](_URL_3_), former Alvin submersible pilot and current Director of the Duke University Marine Lab, studied [the glow](_URL_3_) at hydrothermal vents after finding shrimp with primitive photoreceptors. She then wondered if indeed shining bright lights on these animals was adversely affecting them. In this NY Times article [Floodlight Of Divers May Blind Shrimp](_URL_3_) > ''The shrimp are always there,'' she said. ''So the sense is that the lights haven't blinded them to the point that it's affecting the population density. > ''Individuals may be having their eyes damaged, but in terms of the behavior and ecology of the system, we don't see any effects. If they had all disappeared, we would have wondered.'' There are also more scholarly references I could dig up if anyone is interested. | Certified (PADI advanced, Nitrox, night diving, dry suit) scuba diver here, I won't speak too much to the actual quantity of light down there, because I tend to intentionally night dive on moonless nights, but I can at least tell you that at 70 feet you can't see the brighter colors anyway. Blue and Green are easily distinguished, but red/yellow/orange are all just about the same. This is true in daylight as well as night diving with your light covered. I await a better answer though because I don't know what spectrum fish see in, and how that spectrum penetrates through the ocean. I imagine if they see primarily with infrared or near infrared the colors are entirely irrelevant, whereas if they see UV like certain insects they could be incredibly important. |
Who *are* the Cossacks? | Cossacks are linked in my mind with pogroms and anti-Semitism, but none of the answers deal with this. Am I misinformed? | Adding to /u/snakeskinjim's brief and clear post, here's the etymology of Cossack: Cossack (n.) 1590s, from Russian kozak, from Turkish kazak "adventurer, guerilla, nomad," from qaz "to wander." The same Turkic root is the source of the people-name Kazakh and the nation of Kazakhstan. So they share the same root word but they refer to completely different groups. Kazakh came to denote the warlike nomadic Kazakh people and Cossack became used for rebels in Russia much later on in history. |
How does one retire to another country? | There are no answers that fit every situation, but some countries, such as Thailand, have retirement visas to attract retirees if they fit the requirements. Some countries also have investment visas that can be pseudo retirement visas. | People do this all the time. For example, some Americans retire in Mexico or Thailand, where their money goes a very long way. But most don't. They don't want to be far from all their friends and family. They don't want to be in a country with inferior medical care, inferior police protection, water that's not safe to drink, traffic that's frequently lethal, an unstable government, and a language that they don't speak. |
While in cold weather, why do my hands feel cold when out of my pockets for five seconds, but my face which is also exposed to the cold doesn't? | Your hands are farther away from your heart with veins and arteries more exposed to the temp then your face. Why does that matter you ask. Well your heart pumps the warm blood throughout your body. Also in the cold your body prioritizes where it wants to send heat to keep warm. Your internal organs or the main ones including your brain and your face is right next to it. But ears and nose are in danger from frostbite still. For some extra info a common cure for being cold is alcohol but what this does is release the heat to all of your body making you feel warmer short term but ultimately making it worse in a survival situation as your core body temp is lowered | You hand is filled with sensory receptors. Some are warm some are cold. They NEVER do both. Cold does cold and warm does warm. Sometimes, they get confused and send the WRONG single. This called paradoxical cold and paradoxical warmth. Take a pen and lightly poke around your knuckles. Some places will feel warm while other spots will feel cold. |
Why detox water if I am already having fruits, veggie and drinking water everyday? | Detox is a scam. Your body does not accumulate "toxins" and there is no amount of drinking/fasting/pooping you can do to "detoxify" anything. | Your body, specifically and mostly the Liver, is constantly "detoxifying" itself. That's one of your Liver's full time jobs (the liver is an amazing organ, it has over 500 functions!). If "toxins" were to start to building up in your body you probably should see an MD cause a juice cleanse isn't going to get rid of them. And any toxins that your Liver can't handle (say mercury or something) aren't going to be cleansed by juice either. So yeah basically 98.5% Pseudoscience. TLDR Your body is amazing at "detoxifying" you already. Give the Liver the credit its due. |
How come politicians in the US always reference God in speeches, isn't that a little contrary to freedom of religion (or lack of religion) if God is written everywhere? | The First Amendment prevents the government from endorsing or inhibiting any specific religion. It does not prevent a politician from referencing something related to religion. | The Supreme Court says it's because "God" doesn't refer to any specific deity of any specific religion, so it doesn't leave anyone out. You're right to notice that this is not a very good answer. |
What causes one's tongue to stick to a frozen pole? | Saliva is made up of 99% water, when you stick your tongue to a metal heat is passed from the tongue to the metal as metals are generally very good conductors of heat, thus this rate of heat conductance is faster than the heat which body sends to the tongue through blood, thus the saliva freezes and your tongue gets stuck to the metal surface. | There is a big nerve at the roof of our mouth. When this nerve gets exposed to extreme cold it hurts and sends pain signals to our brain. That's why sticking your thumb to the roof of your mouth will get rid of brain freeze. |
Why I have to wait ten minutes to post another post on Reddit. | Reddit throttles new posters. This means that (until you've built up some karma) you will have time limits posting multiple times. This is to discourage people from making a new account and using it to spam the site with posts. | That wait time decreases the longer you are on the site. It's there to stop people from creating an account and then spamming adverts etc. Eventually you get to a point where there's no delay between posting. |
Why do we look bad in certain mirrors and good in other mirrors? | Likely the light in the room that falls on you when you look in the mirror. The direction and quality of light have an enormous impact on how you look, as different lighting can make you look thin, fat, smooth, lumpy, healthy, sickly, etc. It's also possible that the distance you stand from the mirror will have an impact on how you see yourself. If you're very close to a mirror, your features can look a bit exaggerated and unpleasant (think opening your phone's front camera on accident from really close to your face) | Your face is mirrored. You are accustomed to looking at your face in the mirror and have grown to like that look on the account of you seeing it every day when you look into anything reflective. But as soon as you look at your face in a photograph (which is how you really looks) your brain notices that something is wrong and you don't like it as much. You like your face mirrored; you don't like it as much when you suddenly see it right way around. |
Why do stores not sell cigarettes in smaller quantities than 20 in a pack? | It's called a loosey. When a store sells you a single cigarette. It used to be fairly popular, but for the most part, laws have passed that have banned the sale of single cigarettes, and you can only sell whole packs now. You can still find people and stores who sell them if you're in the ghetto. | Profit margins and overheads in some stores are larger than in others. Sometimes the pack sizes vary in the cheaper stores at other times you see just how much you are being ripped off. |
Why is Mexico so corrupt ? | Because Americans buy drugs, which makes the cartels both rich and willing to use bribes and violence. If you were given the choice between taking bribes worth more than you could ever earn, and being the subject of a Narcocorrido about an official who was murdered, you would probably take the former option. Now rinse and repeat until the cartels are publicly recruiting soldiers with banners in the streets. | Because the drug cartels pay them more money than the government and commit acts of violence towards them and their family if they don’t obey. |
Can pions (or other mesons) form a "nucleus" by binding to other pions via the strong force? | There are [hypernuclei](_URL_1_) which are basically nuclei containing baryons heavier than nucleons. As for "bound states of mesons", there are [tetraquarks](_URL_0_). | Not as simply as that. One of the ways that the strong force is modeled is called lattice quantum chromodynamics, where quarks are placed on the vertices of a digital lattice and the interactions between them are calculated with a computer. It is possible to set up a real-world system of atoms trapped in an array of electromagnetic traps, created with clever optics at very low temperatures. Depending on how this trap is designed, the neighboring atoms interact with each other in different ways, and it may be possible get this lattice of atoms to behave like a lattice of quarks. |
Why do our throats tingle when we clean our ears? | The ear canals, nose, and throat are all pretty connected! The Vagus nerve, which stretches down your entire body's core, can be stimulated when you're cleaning your ears and cause you to get that tingly feeling in your throat. | You have something call "Arnold’s nerve" in your ear which is connected to the "Vagus nerve". The Vagus controls important stuff like coughing and breathing. When you touch the inside of your ear the Arnold’s nerve sends a signal which sometimes the Vagus misinterprets. Instead of telling your brain that you have something in your ear it tells your brain that you have something in your throat. When your brain hears that it starts coughing to remove the nonexistent throat object. |
Why do we lose our sense of "play" as we age? | Just a guess, but maybe it's a learning vehicle wherein we practice life skills. Once we've mastered them we no longer need to "play". | You've developed. You've satiated that intellectual curiosity that you had as a child. You know have the capacity to enjoy bigger and more exciting, more difficult problems and tackle them with the skills you've learnt from play as a child. |
how does the magnetic strip on train tickets work? | They are essentially like a strip of audio casette - a strip of material with embedded iron particles, which is magentised in such a way that information is [encoded onto it](_URL_0_). A train ticket will encode information like the station the ticket was purchased in, the date and time of purchase, train operator, etc (whatever the exit turnstile needs to decide if the journey was valid). This information gets written to the stripe when the ticket is issued, and read back and validated when you swipe it. | The magnetic strip is magnetic but the head of the reader is prone to error if the surface it slides against is not smooth. So if you put a smooth outer layer on the card, the head now glides smoothly along the mag strip and reads the encoded numbers appropriately. |
Why biofuel? isn't it just burning what amounts to man made fossil fuel? how much better is it for the environment if at all? | If a biofuel requires no fossil fuels to produce, it's better because it doesn't introduce new carbon into the system. This is the problem with fossil fuels: when burned, the carbon they introduce into the system is new carbon, in the sense that it has been sequestered and kept out of the system, and now it is being reintroduced. In other words, biofuels take carbon out of the air and then put it back, while fossil fuels take carbon out if the ground and increase the amount of carbon in circulation. Thus biofuels have no effect on the amount of CO2, while fossil fuels increase the amount of CO2 in the atmosphere. | Oh yes - ultimately, it's the same basic reactions, so that burning biofuels isn't cleaner than burning fossil fuels. HOWEVER - the carbon in those biofuels was recently taken out of the air by the plants or algae used to create them - for fossil fuels, that happened millions of years ago. So it's more of a break-even in that sense. |
why don't we just call other countries what they refer to themselves as in their own language? | 99% of the time for historical reasons. Notice that a lot of countries that have different names have been around for a long, long time: Germany (Deutschalnd), China (Zhong guo), Japan (Nihhon). On the other hand, I never heard of the "USA," referred to by anything other than "America," "USA," or "United States" in another language. Sometimes, location names are changed to make pronunciation easier when there's big language differences. Also, you might be surprised that sometimes even the names of individuals change between languages. Confucius's real name was "Kong Zi" but we say "Confucius" because it was easier for Europeans to pronounce back then. | In the special case of Germany, it is one of thee Germanic tribes that other countries call it after. These are the Germans, the Teutons (leading to Deutschland or Tedesco in Italian, for example) and the Allemans (thus variations of Alemanha in other Romanic languages. I guess it has grown historically since there was always some collective noun for those living in the center of Europe, but only comparatively lately has it become a coherent country. |
What kind of injuries or wounds require "keeping pressure on it" and what exactly does that do? | It's a big part of first aid training. Anything that is bleeding. Pressure helps to slow the bleeding. | It's the quickest way to protect the injured part. You pull it away from danger and protect it with an uninjured part of the body. |
Why can you use two different ways(dot product and cross product) to multiply two vectors? | In short, multiplication does two things: First, it can be called "repeated addition". 3x3 = 3+3+3. Second, it can be called "area calculation" . . . . . . . . . With integers, these result in the same thing, but with vectors, you need two different methods to reach each result. This is a gross simplification, but underscores why there are multiple different things that resemble multiplication. | It's purely a human convention. We could define a cross product to give a resultant vector pointing in the opposite direction if we wanted, like how in linear algebra there are different conventions of the order of writing an inner product (usually with regards to whether the left or right element is the complex conjugate). It wouldn't change how the universe works. |
How is Rob Ford still mayor? Shouldn't he be in jail? | You only go to jail if you are convicted of a crime. That has not happened (yet) therefore, no jail. There is no means within Canadian law to remove a sitting mayor. Impeachment (as they have in the US) is not something that exists in Canada. He was stripped of his powers by city council, but the actual title can only be lost via an election or the Provence forcing the issue. The Provence will not do this for many reasons. Here's a good list of the limited way he could have been removed _URL_0_ It's all moot now anyway, dudes likely to die of cancer shortly. | To be absolutely sure he never gets out of prison, even if he qualifies for parole, even if he has good behavior, even if some of his convictions get reversed on appeal. |
Was there any useful science gained from Nazi experiments on their victims? | You're getting downvoted because this has been discussed a lot in the past. As the FAQ suggests, run a quick search. I contributed to a discussion of this in /r/todayilearned a few weeks past [here](_URL_0_). Here's the summary - the science was useless. Test subjects under unimaginable physical and psychological stress are a shitty control group. And - shocker here - the science that was produced was doctored to meet political requirements. All those people died for nothing. EDIT: See my response to the other reply for more. | _URL_0_ "In accordance with the Nazi cross-European policy of genocide against the Jews, the SS "processed" thousands of Romani people, (male) homosexuals, the physically and mentally disabled, intellectuals and the clergy from all occupied territories.[4]" The Nazi's murdered many millions of people, not all of whom were Jewish. |
How does friction cause heat? | > Why isn't only the outer most layer of atoms the ones getting hotter? They are. But they're touching atoms further in, and when they start jiggling faster, they collide with those other, non-surface atoms, causing them to jiggle a bit faster (and losing some of their own friction-generated jiggle in the process). This is the basis for a type of heat transfer called *conduction*, and it's one of the reasons why something cold or hot that is left sitting out will eventually reach room temperature. | Because nothing is smooth. At a molecular level things are bumpy. When things bump into each other there is an energy transfer. If that energy can’t be used kinetically then it gets radiated off as heat. So things bump against each other because they are jagged, and then that energy from bumping becomes heat. |
Why doesn't Teslas (or other electric cars) come with solar panels to recharge while driving? | There's at least one commercially produced car with solar panels. Audi has something called the solar sunroof. All the solar panel does is power a fan to blow outside air into the car when the sun is shining, reducing the temperature inside the car when it is parked in the sun. When it was designed they wanted it to power the air conditioner to cool the car, but they couldn't get enough energy from a solar panel roof to run the AC, so they settled for a fan instead. | buy a tesla and install solar panels and a home battery. Don't buy anything imported or made of plastic. |
How does "Bail" get determined? | It depends on. 1. How likely it is the person will run 2. How dangerous it is for them to be out on bail (how serious is the crime) 3. And it's limited by the constitution which prohibits "excessive bail". So if you have a suspect who has plenty of money and their own jet, bail might be very high. But if you have a suspect who is homeless, even if the crime is more severe, bail might be lower. In some cases though you're not eligable for bail. If you could be senetenced to death/life imprisonment if found guilty you won't be able to have any bail for example. | Bail isn't used for anything ideally. It's held by the court, and then given back to you when you show up at the required time. The bondsman just loans you the amount necessary to pay bail, and you agree to have the court pay him back directly. This only breaks down if you decide to not show up to court. Then you don't get the bail back; problem is, the government is now angry at you, and you owe the bondsman a lot of money for the loan they don't get back. You'll probably be rearrested fairly quickly, and if you live in some states the bondsman can send a bounty hunter after you. |
Is the severity of the flooding in Houston an example of the effects of climate change? | It exists within a climate that has changed. Pointing to any specific climate event is not useful - there have been big weather events periodically throughout history. What climate change predicts is that the frequency of what we regard as 'abnormal' weather will increase. So...will we look back and see this storm as part of a pattern of changes to Houston's weather? Most likely, yes. | I've not heard of a city subject to increased flooding that isn't at least wanting to take measures (some states literally prohibit discussion). But... Flood control isn't sexy / newsworthy that you hear about it That's only one of the symptoms Many people subject live in places that can't afford the infrastructure Prevention is much cheaper, but prevention is paid for by businesses and cures are paid for by governments |
After a planet forms and the debris around it starts to form, what factors determine whether the debris will become a moon or a belt like Saturn's rings? Why in some cases are there both? | One of the big determiners is the Roche limit. The closer you are orbiting to a body, the faster you must orbit. As a result, there is a tension on large satellites, where the part closer to the parent body wants to move faster than the far side. This stress increases the closer the satellite orbits. For a large object held together only by gravity (a "rubble pile"), the limit where the object will no longer stay together is the Roche limit. The rings of Saturn fall well within the Roche limit for a large body. | I believe the best current understanding is that Saturn's rings aren't stable. For example, the E ring is being supplied material from Saturn's moon Enceladus. So even in that context, they are technically falling inward as well, at some rate. |
Why do some companies/stores have rules/policies against pursuing shoplifters? | Legal reasons. You are not a trained security/law enforcement professional. If you get hurt while chasing down someone who decided to lift a few shirts it is the company's ass on the line. It is not your money or goods, don't play the hero. | Because the whole thing is bullshit. The government refuses to regulate the industry, then when people take advantage of it, these dumb dicks all shake their head and act like the scam artist is the one who fucked up. It's like leaving the keys in the ignition of your unlocked Maserati then getting mad that a bad guy stole it. Yeah the thief is a bad guy, but you didn't even do the simplest thing to stop them. |
What is the absolute maximum current that is able to flow through a conductor? | Assuming that the "resistance of 0" implies the wire is a superconductor, then a critical current would exist and provide an upper limit above which the material would revert to a 'normal' conductor. The critical current is just the current necessary to generate an internal magnetic field in the conductor which equals the [critical magnetic field](_URL_0_). Once the conductor leaves the superconducting state, a normal state resistivity would generate heat and further drive the conductor away from the superconducting phase by raising its temperature. The details of how this transition occurs would depend on the specific material (including some aspects of micro-structure and alloying), heat transfer, the initial temperature, and conductor geometry (e.g. coil inductance, etc.) . | > afaik there’s no current (?) anywhere but said path at any given time. That part is wrong. It takes all available paths simultaneously, with the most current going through the lowest resistance. If you have a 1ohm resistor in parallel with a 2 ohm resistor, twice as much current will go through the 1ohm resistor. |
Why do cavities always seem to form on molars even though my toothbrush touches them the most? | Molars have more crevices that bacteria can live in and potentially avoid being brushed away. Also, they are simply larger teeth and thus have more surface area that can potentially decay. | It's because the liquid will manage to get into more crevices, and smaller gaps, than bristles or brushes can. |
What it takes to establish a sovereign nation | In theory, it's very simple: all you have to do is convince the country which owns the land to let you go, then convince most of the rest of the countries to recognize your sovereignty. Or, you can forcefully break away, but then you face an uphill battle in gaining recognition. | Follow up: what is the first example we have of nominally sovereign (or, for sake of ease, capable of waging mutual war and with separate governing bodies) entities rendering such aid? What about during times of hostility? |
Why haven't personal helicopters become a widespread thing? | Humans aren't even able to drive ground vehicles safely. Helicopters require even more skill and willingness to obey the rules. | Maybe the questions is better phrased as ... Why are quadrocopters so popular for small scale helicopters but not for large scale ones? I am curious as well. |
Do animals get bored like a human might? | Yes. An example of people attempting to combat this is the enrichment objects found in zoo enclosures and people getting toys for dogs. All the problems expressed by humans from lack of mental stimulation can be seen in animals. We are animals purselves and suffer from many of the same thibgs. | Obviously they do. Cats, dogs and basicly any other animals aren't stupid. They can differentiate between individuals of their species and others. Just look at the behaviour of a cat when it is confronted with another cat as opposed to a human being. |
What is a rape kit and how does it work? | It is a set of swabs and other devices that allow for the collection of semen, blood, urine, hair, and skin samples that may have been left behind by a rapist. It also has collection containers that can be labeled and sealed to preserve the evidentiary value of any samples. It might also include a camera. The main idea is to provide a standard means of collecting evidence and preserving the chain of evidence, to make it harder for defendants to claim the evidence was tainted. | Its sounds like its promoting rape and violence against women. Victims often hear those things from their attackers. And objectively, it does fit the idea of a rape in progress. Someone says no, but "I know you want it" |
How did Stalin's rivals 'help' him consolidate power in the 1920s? | Because all of those people made serious tactical errors (such as allying with Stalin against each other) and just as importantly, none of them had a base of power within the party that could challenge Stalin's. Stalin as general secretary made himself the de facto head of the party bureaucracy, with great deal of influence/power over appointments of people within the party hierarchy of the entire Soviet Union, which was the real source of power within the Communist party. By contrast Trotsky's base of support was within the red army which sounded good in theory. However Communist parties with its ideological fixation on the French revolution was very keen on guard against "Bonapartism" which meant the army was always firmly subordinated to the party and Trotsky's supporters were largely removed in the 1920s. Zinoviev was the head of the Comintern as well as the Leningrad party apparatus but those positions turned out to be relatively powerless against Stalin's power over the rest of the country. | Both were highly nationalist/militaristic societies that were worried about the Communist USSR. They had similar racist ideals, both dreamed of making Empires so they could make up for their lack of resources like oil, iron, and agricultural land. However, above anything else, they didn't trust democratic nations, and didn't have large amount of choices for potential allies. |
Why is banning half of r/Thanosdidnothingwrong such a big deal? | Because it's a fun thing to do based on Thanos' philosophy of needing to reduce the population in half. | Wow. 7 comments, all of them from shadowbanned users. I guess that kind of answers your question, doesn't it? (Also please tell me I'm not shadowbanned...) Anyway what you're mainly referring to is the banning of /r/fatpeoplehate, which was divisive issue with both supporters and detractors. This latest firing of /u/chooter is much more one-sided and could actually cause wide-spread changes in reddit if the Mods continue to lean on the admins. Only time will really tell though. Some people will point to reddit's growing userbase as a cause. Others want to blame it on interim CEO Pao. |
Why are our teachers forced to teach to a standardized test instead of truly teaching? And how can we fix this? | Because test scores are tied to the amount of funding a school gets in many states. And as long as money is tied to scores, administrators will attempt to get as much money as possible, and cut teachers whose classes are underperforming. So teachers are constantly in fear for their jobs. | If it were the other way around then schools/students would be discouraged from getting high test scores. Why try to teach the kids when you get more funding if they are idiots. |
The Mandlebrot Set and fractals in general. | The mathematical rule that creates the Mandelbrot set is relatively simple (at least, if you're comfortable with complex numbers from a decent algebra class). It works like this: Pick a complex number *c*. Let's say we pick c=1. Once you've picked it, start with zero and repeat the following process: square the previous number, than add *c* to it. In this case, we'd generate the sequence 0, 1 (0^2 + 1), 2 (1^2 + 1), 5 (2^2 + 1), 26 (5^2 + 1), and so on, and this sequence runs off to infinity. On the other hand, if we picked c=-1, the sequence would go 0, -1 (0^2 + -1), 0 ((-1)^2 + -1), -1, 0, -1..., and never runs off to infinity. The Mandelbrot set is the set of all numbers that do *not* run off to infinity this way. | Most images consist simply of a grid of pixels. Since mathematical formula are plotted on a graph with x and y coordinates, translating a mathematical formula into an image is basically just taking the x,y coordinates for each pixel in the image, plugging it into the formula, and determining whether that pixel is on the plot or not. Things like the mandelbrot set are a bit more complex. While you can simply plot which coordinates are in or are not in the mandelbrot set, people like to get a bit more creative and add color schemes base on how far in or how far out that coordinate is in the mandelbrot set. |
Why is there no A to Z list for everything by genre on Netflix Instant Stream? | Because searching Netflix in that manner would draw attention to how much isn't available. They don't want you to come with your ideas in mind, because you won't find them, but they'd rather that you look around and see what you like from what they have. | It's because of the licensing agreements that Netflix has with the various studios. I'm sure they'd much prefer being able to stream every movie. The studios don't want to because they don't want to cut into their profits from things like Pay-Per-View and DVD sales. |
With the mid-west's extreme droughts, and much of the crops lost... How much good has genetically engineered crops done? | To clarify are you asking solely about the benefits of genetically engineered crops in respect to drought tolerance? Or just the benefits of genetically engineered crops in general. | We have. Most staple foods in the industrialized world are [fortified](_URL_0_), starting with the humble table salt. We're not yet up to having genetically engineered crops grow already enriched. Part of the delay is the hysteria regarding anything "genetic" (sometimes it's almost almost as bad as "nuclear"), but we'll get there eventually. |
Does cake cook faster if the temperature is more than what is prescribed? | The outside of the cake does. Some things say 350 degrees for 30 minutes because it takes a long time to sufficiently warm up the center and cook all the way through. If you did 450 degrees for 20 minutes, the outside will get cooked quicker, but the center may not be able to heat up enough. Upping the temperature will speed up how quickly the outside of the thing warms up, but may not do the same for the center. In short, upping the temperature and decreasing the time is a good way to get something under cooked in the center but burnt on the exterior. | There's two main reasons why that doesn't work: 1. Heat takes time to actually conduct through something. If you tried to bake a cake at 1000° for a minute, you'd end up with a scorched outside, but the inside of the cake would still be gooey batter. The heat just doesn't have time to move its way through the substance. 2. The chemical reactions that make food "bake" only happen at certain temperatures - a good example is the Maillard reaction, which gives browned food (meat, bread, toasty marshmallows) their flavor. That happens right around 300° F or so. So you need to get to at least that temperature to get the food cooking properly. But if you go too much higher than that, you start reaching the temperatures where food doesn't just brown, it burns. So if you scorch your food at 1000°, you'll skip the delicious browning temperatures and cut straight to burning them. No bueno. |
Why are spiders unable to crawl on another spider's web? | Spider webs are made up of both sticky silk (for catching stuff) and dry silk (for walking on). Spiders memorize where it's safe to walk and where it's not when building their webs, but a spider on a unfamiliar web won't know where the different types of silk are. | Air flow. If you see a web in your house, there is air flow in that area. Flying insects use air flow to move. Spiders eat flying insects, so they set up shop where the highway for their food is. |
What happens if we break "war laws" like the Geneva convention. And how does it make sense to have rules for war, whenever countries are fighting to survive, not just to "win" like in some game? | 1. The understanding is that should you break the rules you will be punished by the other nations who abide by the convention. 2. Simple, there are some things that are horrible enough that we just don't want to see them used. A good example is chemical warfare, things like mustered gas or napalm. The horrors these weapons inflicted where enough for nations to agree to not use them. Why doesn't one side just use them anyway? Because they don't want the opponent to do the same. If I go and napalm China that gives them grounds to do it back, and if if it was effective against them it will be against me as well. | The Geneva Convention establishes rights for prisoners of war, not for criminal punishment within a state. A member of a states military is considered a lawful combatant during a war. They aren't considered criminals. The Geneva convention was established to give fair treatment of prisoners of war. It was written at a time tobacco was often part of rations. |
why do I wake up when my dog stares at me, but doesn't make a sound or touch me? | How do you know that your dog is not staring at you for hours? | They are paying attention to your face and where you are looking. They will not stare directly into your eyes, as this is a threat signal, but they look at you sidelong and watch your face. I'll discuss dogs since most of this work has been done in dogs. Dogs understand human facial expressions to a point and preferentially look at faces, according to studies using eye-tracking software. Eye contact is part of canine body language and dogs know where your eyes are and understand that you can only pay attention to them when you are looking at them. Attention studies show that dogs preferentially seek attention from people whose gaze is directed towards them and unimpeded. There's also the simple fact that if most animals have a simple neurological orienting response that makes them turn their head toward a sound. The sound is coming from your face, so that's where they'll look. |
My family immigrated from modern day Turkey to the Amalfi Coast in the mid 1500s, what can I take from this historically? | If you don't mind me asking, how do you know so much about your family from 500 years ago? That's really cool. | Since being a peasant was so low on the socio-economic tier, not a whole lot would change. This was a time before nationalism, so dynasties ruled over lands and people. I can for sure say they will be responsible for the [Jizya](_URL_2_) tax that non-Muslims had to pay in order to practice Christianity. It also came with other exemptions. This created a tax and political incentive to convert. Most Muslim conquests did not follow forced conversions at sword point. Peasant boys would be at risk of being enslaved and pressed into service and converted Islam to become a [Janissary](_URL_1_). These were a class of soldiers in the Ottoman Empire that became rather influential politically. Edit: This wasn't meant to be comprehensive of all of the changes in a Balkan Christian peasant's life, just two of the most well documented. As Smackaroo stated The [Devşirme](_URL_0_) was the system that recruited Balkan boys into the military and government. |
What is fudge made out of and how do you make it? | This is a perfect job for a google search: _URL_0_ Most are simply melted chocolate, butter, a sweetener of some sort, and some dairy product (milk or cream). Nuts and/or extra flavoring added by additional ingredients as necessary. | It's made of synthetic rubber. It used to be made from plant extracts - natural rubber, in effect, but these days for consistency it's synthetic. |
If a pregnant woman requires a blood transfusion can the woman’s blood type be used or is O- blood needed due to the child’s potentially different blood type? | A woman’s blood supply does not mix with the baby’s. The placenta acts as an exchange point for nutrients and oxygen, otherwise the mother’s blood cells would develop antibodies to attack the baby’s cells. Sometimes red blood cells do manage to mix which happens closest to childbirth, and that’s what causes jaundice and anemia in babies. So in essence, a woman would receive her blood type. Women who have Rh negative blood who are pregnant with an Rh positive baby can also have these issues occur, it’s called Rh Disease. You can get shots and antibodies or something to prevent the chance of blood type related issues causing miscarriage. Hope that helped! | The transfusion does contain the other person's DNA if it has white blood cells in it, but your body isn't really looking that closely at it. Your immune system looks for improper markers on the cells, ones that shouldn't be there. If you have Type B- blood and get a transfusion of A- or O+, your body would destroy it, because the A or the + are foreign. As long as there aren't any markers you shouldn't have, the donated blood works as an acceptable substitute until your own blood can replace it. Edit: red blood cells lose their nucleus at maturity and carry no DNA. |
Why aren’t older gaming consoles emulated on phones these days? New phones have powerful processors/displays and should be able to handle NES, SNES, Sega Genesis, etc. right? | There are emulators out there, as well as emulators for early PC games. I'm not sure why you think there aren't. The reason the original companies don't make the games again is that it doesn't make much money. So you have to rely on community programmers instead. | From a purely theoretical standpoint, any digital computer can emulate any other digital computer, provided that you know how the target system works, and not necessarily in real time. An emulator is just a program that reads the program code for a game system and acts on the code in the same manner as the game system would. Emulators typically intercept graphics calls to allow them to be scaled up for more powerful systems, though. |
Where do the blood cells of earthworms form? | So earthworms have two different circulatory systems, an open coelomic fluid system (fluid filling the central body cavity called the coelom, and which also acts as a hydroskeleton) and a simple, closed blood circulatory system. In place of a heart there are little muscular arches around the coelom to do the pushing. The blood itself is ameboid-formed cells and free, dissolved haemoglobin. The ameboid cells, I believe, derive from the epithelial tissue of the Coelom itself, though I could be wrong. | Red blood cells are formed in marrow, not the entirety of the blood. Only vertebrates use red blood cells. Some invertebrates have freely dissolved hemoglobin (the protein contained in red blood cells) while others don't use hemoglobin at all. |
Why are bugs attracted to lights, are they looking for warmth? And then why do they stay at the light source till they die? Why don’t they figure out there’s no nourishment here and move on? | Bugs aren't attracted to lights. Rather they don't understand that they are lights to begin with: they think those lights are the sun. Bugs use the sun to nagivate. But when the light source you think is the sun (a giant ball of plasma millions of miles away) is instead a lightbulb (a tiny bulb a few feet away) that will screw up your navigation. | They aren't attracted to it. It confuses them. Flying bugs like moths and such use the sun and the moon to navigate. Because the sun and the moon are so far away, the look like the don't move at all when we do. However, at night humans make lights that are much brighter than the moon is and the bugs try and use these lights to navigate. Problem is, our lights change relative position very easily because they are so close. As the bug tries to compensate for this it ends up spiraling inwards towards the light. Kinda sad really. |
Why aren't there separate sports leagues for people who do steroids/performance enhancing drugs? | Because doing so would encourage the usage of performance enhancing drugs and that's not something society wants. Using performance enhancing drugs to try and go beyond what normal athletes can do is already unhealthy enough, having athletes try and out drug other drug using athletes would be quite a bit worse for them. This is made more problematic by the fact that many top athletes start training their chosen sport at a very young age, if you wanted to excel in a competition where drugs are allowed you'd likely have to use these as a child as well. On top of that while seeing how far we can push the human body using every available option would be interesting the overall competition likely wouldn't as interesting as any achievement made while using drugs likely wouldn't be considered as impressive as a smaller achievement without using drugs. | Testosterone can be used for cheating in athletes, and has high potential for unsafe abuse. You might as well ask why steroids are illegal, its just as good a question. |
How can some older video games run smoothly on PCs while some other old games cannot? | I can think of a couple of easy reasons: * The game relies heavily on hardware that hasn't actually gotten much better since release. If a game was built on technologies that assumed your computer would have a single processor, all of the multi-core processors and fancy video cards in the world won't change much if your single processor cores aren't fast enough. * You're actually emulating the original hardware or software. Maybe you're trying to play a Gamecube game. The emulator makes your computer do a *ton* of extra heavy lifting to pretend it's a console, even if that console wasn't very strong. By way of analogy, the open desert is a simple scene, but if you wanted to build the illusion that someone on the streets of New York had taken a wrong turn and ended up walking across the Mojave Desert, you'd have to pull off one hell of an art installation. Your computer has to sell that illusion close to perfectly, and hope the game it's running doesn't notice any flaws. | Video game consumers consoles are computers however they are not PCs. They have a very niche set or hardware and are designed in a way do that game developers can get a lot of performance out of relatively modest hardware because they know EXACTLY what they are working with. Conversely, PC game manufactures need to develop their games with the highest performance in mind, but also need to perform on the mid range cards. The reason that consoles are not always backwards compatible is because the architectures and hardware changes from generation to generation. When this happens, they can no longer directly support the older generation and must often be accomplished via emulation. There is a MASSIVE overhead in performance requirements for emulation and the console simply doesn't have the chops |
Why, biologically, does rubbing one's eyes make them red; and what do eyedrops do exactly to treat this? | When you rub your eyes it stimulates the blood vessels and causes them to get bigger (dilate), so you see more of the red. Eye drops that "get the red out" are called vaso constrictors. They cause the vessels to get smaller (constrict), so you see more of the white. | You have blood in your hand and in your eyelids. Blood is red. |
Do people with autoimmune diseases or dangerous allergies get colds/flus less often? | I wouldn't say it is an "overactive immune system" as much as it is just a malfunctioning immune system. In autoimmunity your body makes antibodies to your own tissues, so your immune system is attacking yourself. A popular way to treat people with autoimmunity is by knocking their immune system down a bit actually, so people with immune system problems are actually more likely to get colds/flus in some cases. Getting a flu shot is super important for these people. | Autoimmune disease is just a blanket term for when your body reacts to a part of itself in the wrong way. How exactly it does that, what body part it is, and the underlying cause varies a lot. I wouldn't say they're almost all identical in each type. Diabetes mellitus I, IBD, multiple sclerosis, and lupus have quite different symptoms from each other, even though they may share a couple. |
What's the difference between mechanised, motorised and computerised? | If something is "mechanized" it utilizes a mechanical advantage. Things like levers, gears, screws, etc. Motorized means that it incorporates some sort of motor...electric, internal combustion, whatever. Typically means that it is also mechanized. Computerized things include an electronic computer system. May or may not be mechanized / motorized. | For an ELI5 topic you've summed it up pretty well! Machines build computer parts now (cheaper, much much more precise and accurate, etc) but electrical engineers design the parts! You can differentiate between the two roles by thinking of computers as hardware and software - hardware refers to physical parts of the computer (the processor, RAM, etc) while software refers to programs and applications (ranging from the operating system to your internet browser to the anti-virus scanner you have)! |
Bandwidth. What exactly is it and how does it work? | Bandwidth originally is from transmission techniques that use bands of frequencies (eg: radio waves). Each station gets a range of frequencies to use (called a band) and is allowed to fill up that band with their broadcast transmission. With clever technologies, you can send multiple different broadcasts within the band you were given. the size of the range, or bandwidth, determined just how many streams of information you could send at once. More generally, the term is now used to refer to how much stuff can be sent through something at one time. For instance, if you have a 100 Mbps connection, it means you are able to send, at most, 100 million bits of information through the connection every second. TL;DR: bandwidth is the maximum amount of stuff we can stuff through a pipe within a given time frame. | It doesnt. In network bandwidth is how many bits you can send per second. Bandwidth have many many different meanings. |
What makes things sharp and is there a limit to sharpness? | Sharp things have a tip with very small cross-sectional area. Sharp things work by concentrating force on a very small area to cut stuff. To make something sharper, make the tip cross-section smaller. To make something duller, make the tip cross-section larger. With sharpness, force per unit area (otherwise known as "pressure" or "stress" or "traction") is the name of the game. Sharp things exert greater local pressure than dull things, given a constant applied force. This pressure will cut/shear objects because material strength is dictated by something called the *yield stress*. That is, materials have a stress limit of how much they can take before they break. Thus, sharper knives will "break" (or yield) the material sooner than a dull knife. | The way I understand sharpness has nothing to do with molecular structure, although yes, some steel can be sharpened to a finer edge, it all comes down to surface area and force applied, a sharp knife has an extremely thing dge tus the force per area is much greater, while a dull edge spreads out the force. at an atomic level im not really sure what happens, although i do know in some medical procedures, glass and obsidian knives are used because they can actually be broken into a very thin atomic edge, only molecules thick |
Why are pain management doctors required to obtain periodic drug screens but medical insurance companies not required to pay for those drug screens? | Liability. The drug tests are to prove that the patient is actually taking the prescribed drug and not selling it, especially if it's a narcotic. If the patient is accused of selling their prescription narcotics, and the doctor has blood test results that support that accusation, the doctor can be charged with a crime. In addition, if the insurance company is found to have aided in the purchase of these narcotics (through medical coverage), they could be found liable, and assessed a fine by the federal government. As for why the drug test isn't covered by the insurance company? That depends on what the test is submitted as. If the doctor's office submits the claim as "Insurer Mandated Drug Test", the insurer is probably going to reject that claim. If it is submitted as a generic "Blood Test", it has a better chance of being accepted as a valid claim. | In order to take insurance from a company, the doctor must negotiate, in advance, what prices they're going to charge for services. They then need to make sure that they have the appropriate billing/reporting policies/procedures/systems to submit bills and actually get them paid. It might not be worth the extra work to take a small insurance company. A company might not pay enough for certain procedures. Maybe the doctor just hasn't gotten around to accepting that insurance. |
Why is Cos(a) used when its the same thing as Sin((a)+PI/2)? | For convenience, because it saves having to write out sin(a + & pi; / 2). Most of mathematical notation is shorthand for something. Even though the cosine function is the sine function with a phase difference of & pi; / 2, it's useful to treat it as a different function in many areas of mathematics. | The value is derived from the position on a unit circle. That is, if you draw a circle with a radius of 1 unit and draw a ray from the center out at a given angle, they intersect. The cos and sin are the x and y coordinates of that intersection point respectively. The value is a ratio. So when you have a circle of a different radius than a unit circle, you can apply that ratio to the radius to find the x and y coordinates at a give angle on that circle. The hypotenuse in the definitions to calculate sin and cos is the radius of the circle, so when you divide the opposite or adjacent by the hypotenuse, it's essentially normalizing the ratio down to a unit circle again. |
why aren't traffic lights made with one light that changes color instead of three. Wouldn't they be easier to manufacture and install? | Several reasons. Technology has only recently evolved to where this would actually work. Prior to LEDs, all bulbs were white with colored filters in front of them and having the filters change mechanically would be a huge failure point. Our eyesight notices movement much quicker than color changes and the change in location of the light acts like motion. And what about all of our color blind friends? The position of the light helps them to know which one is on. | Redundancy and improved visibility. The redundancy comes in to play if for some reason one of them fails, the other still would function fine. In visibility, simply having a second light increases your chances of seeing it. |
Why don't practical superconducting applications use liquid nitrogen-temperature superconductors? | First of all: these applications are pretty much all for creating large magnetic fields. A current is run around a coil of superconductor, which induces a magnetic field inside the coil. The larger the current, the larger the magnetic field. Well, it turns out that supserconductivity doesn't play nicely with magnetic fields. So if the current is larger than a value called the critical current, superconductivity is destroyed by the magnetic field that the current creates. And once the superconductivity is destroyed, all your reasons for using the superconductor instead of a normal material are gone. High temperature superconductors (the ones superconducting at liquid nitrogen temperatures) actually have fairly low critical currents for somewhat subtle reasons involving vortices, which I'm not going to get into at the moment. The upshot: due to material properties, these high temperature superconductors can't create as large of a magnetic field as we need. Low-temperature superconductors can. | Disclaimer: Not a computer scientist or an electrical engineer. Electronics are made to run in reasonable human temperatures, in the 20-40C range. Liquid nitrogen is around -210C, which is noticeably out of this range. I'm too drunk to remember the equations from undergrad physics for the electricity, but there would definitely be problems with brittleness, not to mention the liquid nitrogen offgassing and suffocating anybody nearby without adequate ventilation. If you wanted to be cute, superconductors work at extremely low temperate, and are usually cooled by liquid helium (-260C ish). You could probably make a superconducting processor if you were willing to cool it. |
Different bullet types and their pros/cons | Full metal jacket means that the lead bullet has a thin coating of metal around it. These bullets are pointed at the tip. Pros: Since the lead is coated there is less residue in the barrel after shooting. Con(?): Since the tip is pointed and covered in hard metal, this kind of bullet pierces without expanding much. Soft tip bullets have a flat tip with the lead exposed. These expand a bit when hitting the body (meaning, more damage) but are a little dirtier in the barrel. Hollow points are soft tips with a little scoop taken out so that they really expand when hitting something. Armor piercing bullets have a hard little core of VERY hard metal so that when the bullet smashes into something hard, the metal core punches through it. | Vests use fibers, very strong fibers made from Kevlar or Spectra. These fibers will stop most blunt objects but knives are sharp, they can both cut and/or separate the fibers and allow penetration. Very sharp bullets can do the same thing. Soft-armor piercing handgun rounds are pointy and basically do the same thing. EDIT: I can't tell you how many times I've heard hollow-point bullets referred to as 'cop killers' and nothing could be further from the truth. |
why don't we let people commit suicide? | Suicide is quite often a spur of the moment decision where something such as depression and opportunity (walking over a bridge, going to work by train, etc) coincide. They are not normally planned in advance. Take away that spur of the moment act and most people will never attempt suicide again. | By the time of the mass suicide, many of these people had basically thrown their lives away. They had alienated family and friends, quit their jobs, given everything they owned to Jones. They had burned their bridges, and they had nowhere else to go. In those circumstances, a person has two choices. Admit that everything you've said and done and believed was a lie, or follow it through 'til the end. I believe many of them committed suicide because they simply couldn't do anything else. |
Is the possible number of combinations for a 5-digit number(each able to contain 0-9) 99999? | In general, in base b, there would be b^n possible combinations of n digits. For your question, you can substitute b = 10 and n = 5 to get 100000. You might have accidentally excluded the combination 00000 when you came up with 99999 as the number of combinations. However, this includes combinations that start with 0 (e.g. 00135), which are not normally considered to be five-digit numbers. If you want to exclude those (and assuming n > 1), then you subtract away all the combinations starting with 0, of which there are b^(n−1), to get b^(n)−b^(n−1) = (b−1)b^(n−1) as the final answer. | 9 digits is 1,000,000,000 unique numbers, yup. One billion numbers. You're not even close (In reality, less of them can be used because some stuff is reserved for special uses, but still its tons) |
Why do people sometimes still feel lonely despite regular social interaction? | I think it has something to do with emotional connection with the people you interact with. You can interact with 30 people in a day, but if none of those people are close enough to you to be able to share real emotions with, it remains unfulfilling. | Areas of the brain that typically used for various social behaviours are pruned if inactive. This is why for instance if you don't learn to speak by age ~12 or so you will never really learn to speak. We've evolved to have these traits in our brains but they only work if exercised in a community. |
- Why does heat help myalgia (muscular pain)? | Your nerves are bad at multitasking. If you add heat, they have to send a signal to the brain that there is something hot on your body. Temperature also have precendence over pain, hence a lot of your nerves will stop telling your brain about the pain since they are distracted telling it about the heat instead. | Icy Hot typically contains menthol and camphor. [Menthol](_URL_1_) is an oil extracted from mint plants that triggers the sensors in your skin that detect "cold", so it creates the sensation of cold without the temperature actually being cold. [Camphor](_URL_0_) is also an extract from a plant, or can also be produced chemically. It's absorbed by the skin and produces a warm and cold sensation, as well as a little bit of numbing of pain. The basic idea is that the hold and cold sensations keep your brain distracted from noticing the soreness of the muscles, and the camphor also numbs the soreness / pain a little bit. |
Considering recent prices in oil, is it possible for an individual to buy barrels then resell them when prices rebound? Can individuals participate in the oil trade? | The contract size for the futures market is 1000 barrels. There might be some start-up somewhere selling fractional contracts, but I don't know of any. There are some ETFs like "USO" which you could try. (I'm not saying it is a good idea, just that it is available) It is unlikely you would be able to find someone to deliver 10 barrels of oil to your backyard at a reasonable cost. And even less likely you would find someone to buy it back from you later at a reasonable cost, as they would not know what grade it really was or what happened to it while it was in your back yard. | Doable - Yes Economically Viable/Cost Effective - No Oil is kind of special. Its price per gallon is high enough that spending a few hundred million to move it across country is viable. Water is no where near as valuable. Could we pump it across country, yes. But it would be a huge cost for basically no value. |
Is the science that Walt White uses in Breaking Bad real? Could you melt a body in acid like that? Could you make poison out of beans? Could a chemist really cook the best meth ever? Was meth really legal once? | The acid used in Breaking Bad was hydrofluoric acid (chemical formula: HF) which is actually a weak acid. Even though it is a weak acid, it is extremely corrosive to metals and glass and very deadly to humans. If you spill hydrofluoric acid on yourself, the acid will be absorbed through your skin and will start attacking calcium in your blood and in your bones. This causes a huge change in the calcium ion balance in your blood and can lead to cardiac arrest. A lethal exposure is as little as 25 square inches of skin. It doesn't make your tissues mushy as depicted in the TV show. When cleaning up, Walter and Jesse will also be exposed to the acid fumes which can cause similar poisoning of the skin and blindness with eye exposure. As a chemistry teacher, Walter should have be more aware of the hazards of HF exposure. | I doubt it would be considered evil, hard drugs where available in chemists up until the great war. Edit: lol why downvote a fact? |
Why do many viruses and bacteria (attempt to) kill their hosts? Wouldn't it make more sense to keep their hosts alive so they can spread as much as possible? | They don't actually try to kill their hosts. What they try to do is to reproduce and survive, just like any organism. If they do kill their host, this is usually unintentional - an accident - as normally this is bad for them too. It is mainly a side effect of the behaviours (virulence, ease and speed of transmission) that make them successful in the first place. | > but if it eventually kills the host, doesnt it die as well? Diseases don't *want* to kill the host. They simply 'want' to (or more precisely, have evolved to effectively) reproduce, as you point out. Killing the host is an unintended consequence. This can be good or bad for the disease causing agent itself, if it can be spread by the corpse being eaten, for instance, or if it is so lethal that it tends to wipe out a population faster than it can spread (as ebola has done in the past). Many diseases don't kill their hosts, and this also tends to present advantages, such as enabling it to be spread more thoroughly and keeping its 'food supply' alive. |
Why does the sun appear yellow when its peak wavelengths are blue-green? | Blue light gets diffracted easily, whilst red light doesn't diffract a lot. When the blue wavelengths hit our atmosphere, they spread out creating what we know as the sky. Red light keeps a more direct route, which appears as the sun. The same phenomenon can be used to explain sunrise and sunset skies. | > Is this because there is so many different atoms in the sun that they appear as a spectrum or is it something else that causes this phenomenon? Something else. The continuous spectrum from the sun is a consequence of blackbody radiation due to how hot the sun is. That is the same phenomenon that causes hot metal to glow and dirty flames to appear orange. If you look at [the solar spectrum](_URL_0_), you can see the standard continuous spectrum from blackbody radiation along with thin lines corresponding to spectral lines. |
Are human emotions universal across all cultures? | Not my area of expertise, but work on [microexpressions](_URL_0_), most notably the work of psychologist [Paul Ekman](_URL_1_), has shown that facial expressions for basic human emotions are universal across human culture, and seem to be 'hard-wired' into the human brain. So at least for *expression* of human emotions, research seems to indicate that they are generally universal. As for whether the emotions themselves are universal, to me it sounds like an emotional version of the 'is the color red I'm seeing the same as the color red you're seeing' kind of problem, but some psychologists and/or anthropologists need to weigh in to get a more definitive answer. | You’re right with the learned part! A lot of it is from modelling parents/older siblings etc... however humans (regardless of race, age, gender and so on) have 5 innate facial expressions (happiness, sadness, disgust, anger, and fear [recognise these from anywhere?]which are linked to emotions—which implies they are also innate. So yes you’re partially right, but you may also be on to something with being able to detach your emotions, very interesting idea! |
Did people living during the Cold War believe it would ever end? | From the perspective of the United States State Department, yes the Cold War would eventually end, but no it was not going to end in the twentieth century. When the State Department drafted vision statements for various Eastern European nations, for example, they always assumed that at least some of these nations would join the European Economic Community (the precursor to the European Union) after the Cold War ended. They were right about that. They were very wrong in predicting when the Cold War would end, however, as even in the 1980s during the period of Perestroika and Glasnost ("restructuring" and "openness" in Russian, i.e., the period of Soviet reform under Gorbachev), the State Department continued to assume that the Cold War would continue for decades. As all historians of the period are aware, so too did the political scientists of the time. This is obviously just one perspective (the American diplomatic perspective), and I am still interested what others will have to say about this topic. | Are you talking about WW2, or the Cold War? |
Do cell phones give off more 'radiation' during an actual phone call rather than being just being on and 'idle' ? Also, does placing a smart phone in "airplane mode" make the 'radiation' any less? | Cellphone and the base station alter the power level dynamically based on reception quality and signal strength. When you are close to the cell tower, the power used is much smaller than whey you are in the area where reception is weak. Cell phones send more radiation during the phone call. When cell phone is idling, it sends only periodic "checks" to the cell tower to tell it's location. During the phone call there is continuous signal. In the airplane mode all this stops. FM receiver, Bluetooth, wireless LAN and GPS should work but not the cell signal. | For an off-the-shelf phone no effect has ever been demonstrated. Reports have been made, but none were reproducible. Scenario: You are a pilot. Something isn't working. You don't know why. Have the flight attendants do a check. Someone's phone was on. Have it turned off. Plane starts working now. Report that the phone fixed it. Was it really the phone, or some other source of interference? Probably the latter. |
What is the difference between SSD and HDD? | [This](_URL_1_) is the innards of a (somewhat older) HDD. The data is stored on those disk through the use of magnetic fields. The read/write arm has a powerful magnet for writing, and a sensor for reading. There is a circuit board in there for controlling the arm and platter motors, and interfacing with your computer. Because of the way the data is stored, the read and write speeds vary depending on where on the platter the data is stored. [This](_URL_0_) is the innards of a SSD. There are no moving parts, which means that the seek speed (time it takes to find a sector on the drive) is a whole lot faster than an HDD. The read/write speeds are also up to 10 times faster, and is consistent over the drive. | SATA isn't a drive, it's a interface used to connect drives to the motherboard. Your HDD and CD/DVD drive are connected to your motherboard using a SATA cable. There are also multiple versions: SATA 1.5 Gbit/s, SATA 3.0 Gbit/s, SATA 6.0 Gbit/s. SSD stands for Solid State Drive, it's like an HDD, but instead of a disk it has multiple chips (Like SD cards). A SSD is also (Usually) much faster and more expensive than a HDD. A SSHD (Solid State Hybrid Drive) is a hybrid between HDD and SSD (Explained above). It combines the speed of an SSD with the storage capacity of an HDD. It is cheaper than a SSD, but it also isn't as fast. Thunderbolt is an interface created by intel and apple. It is like an USB, only much faster (Twice the speed of USB 3.0), it can also send data both ways (Send and receive) without slowing down in either. The reason why it isn't massively used is because it is expensive. It can be used to connect multiple screens, computers, drives, etc. |
If the universe is expanding, and all objects with mass exert gravitational force on all mass and energy in the universe, does that mean that the gravitational potential energy of the universe is increasing? | Energy is definitely increasing over time. Energy is only conserved in systems that are time-independent, and an expanding universe is clearly not such a system. | Forms of energy which are not mass do indeed contribute to gravity. Light is one example, but most of the time the energy density of light is far too small to have a significant effect compared to all the other stuff in the universe. However, in the very early universe, there was a time when the energy density due to radiation dominated the expansion of the universe. |
Why can't everything mix with water? | It's all to do with affinity, the attraction of one molecule for another. Water molecules are polar - they have positively charged hydrogen ends and a negatively charged oxygen middle. Opposite charges attract so water molecules have a high affinity to each other. Oil molecules are non-polar, no great charges are present, so they aren't attracted to water molecules particularly. The water molecules would rather stick to each other than to the oil. That's a very simplified explanation, some molecules, like ammonia gas, will actually change chemically with water so they dissolve. Some will dissolve to a limited extent then only the excess will form a separate layer. | Imagine you have two jars of jelly beans. One is filled to the brim, the other is half full. Shake them both. Which one will get more mixed up? In order to shake up the juice it has to move around. The juice on the bottom has to be able to move up to the top and all around. But if there is no empty space, then there is nowhere the juice can go that isn't already filled with juice. For a shorter version. Have you ever tried to have a splash fight in the pool underwater? |
How do fans cool air? | They don't cool air at all. In fact, they make it a little bit warmer (like pretty much everything that moves or uses electricity, fans generate some heat). But moving air helps your body stay cool. The main way your body gets rid of heat is by sweating. The sweat on your skin evaporates and takes some heat with it in the process. But air can only hold a certain amount of moisture, so if the air around your skin stays still, you won't be able to evaporate very much. If the air is moving, you'll get a steady supply of low-moisture air around your skin to evaporate into, helping your body stay cool. | They don't make cooler air, they help blow warm air away from the surface of your skin as well as help evaporate sweat from your skin, cooling it down. |
Could we send an unmanned satellite into long-term orbit around the moon? | We can and have built satellites for long-term lunar orbit. [Lunar Reconnaissance Orbiter](_URL_0_) has been in lunar orbit for the past 5 years and may get a mission extension for another 2 years. This would be as long as some GPS satellites' designed lifespans (see [here](_URL_1_)). | Due to the tidal effects from the host planet, orbits around a moon would not be stable in the long-term. In the short term, you can orbit a moon just like any other body, but we don't expect to find natural satellites of moons due to how brief the arrangement would be. |
why nobody make ''organic tobacco'' with no added chemicals. | > perhaps maybe the only added ingredient could be nicotine Nicotine isn't added. It's a naturally-occurring chemical in the tobacco plant, and is the entire reason that people started smoking tobacco in the first place. And most of the harmful chemicals aren't added. They're naturally produced by burning the tobacco. It should come as no surprise that burning organic material and breathing the smoke is bad for you. There's a reason that you're supposed to crawl below the smoke in a house fire, after all. | They don't "put nicotine in," like it was caffeine in a soda or something - it's part of the tobacco leaves themselves. |
Traffic engineers: what causes the pulsatile flow ("stop-and-go") nature of traffic on congested freeways? | [Here's an informative video](_URL_0_) It doesn't exactly explain the phenomenon, but it can give you an intuitive sense of how positive-feedback can lead to such behavior. Basically, people will naturally over-compensate to traffic patterns. If someone ahead of you slows down, your reaction is typically to slow down even more. There are also delays in speeding back up again. Slight variations in speed get amplified in such a system, causing the traffic pulses. A traffic engineer could probably tell you more about what sorts of conditions you need to get this behavior, and how they attempt to mitigate it. Koyaanisqatsi has a wonderful scene where the camera follows one of these pulses for what appears to be a good mile or so. | Highways make more people travel by car. This effect is often bigger then the size of the highway so you might inadvertently cause traffic to move slower. For example if you were to build a highway from a city to a nearby town then a lot of people will move out of the city to the town and a lot of the people living in the town would take work in the city instead of locally. And not only work but people would go to the city more often for events and other things. So by creating the highway you now have a massive increase in traffic. |
why do all my pills taste bitter? why dont they just sugar coat the whole thing with the powers of modern medicine? | Most of the time, bitterants are added to the chemistry to make sure that children don't drink a gallon of the stuff. if you're five, and you get a brightly colored gelcap that looks like candy, and you bite it and it DEFINITELY doesn't taste like candy, you're probably going to put it down and go do something else, rather then eat a bunch and get a fatal dose. on the other hand, if you know what's in it and know it's going to help you, and know how much to take, then you can work through the bitterness and swallow your medicines. | A bitterant (specific chemical to make the medicine taste bad) is often added, in increasing amounts, for medications as the danger factor rises. This is to keep little kids from killing themselves messing around with pills. If you ever took Prednisone, you'd know what I mean by bitter. edit: this also is done with SD Alcohol (denatured alcohol). It's plenty drinkable, but to avoid having to pay excise tax, they add a chemical to make it disgusting. |
Was that "young handsome stalin" photo edited at all by the Soviet government? | I don't know whether it was edited by the Soviet government but it was certainly edited by Wikipedia contributors. When you look at the file's [history](_URL_3_) you will notice that it started out like [this](_URL_3_) when it was originally posted in 2005 and it was changed to [this](_URL_3_) in 2007. | Before computers, photomanipulation was done primarily with airbrushes. [The Commissar Vanishes: The Falsification of Photographs and Art in Stalin's Russia](_URL_0_) is right up your alley; it's all about how artists "disappeared" people that were disposed of by the regime, or had otherwise fallen out of political favor. |
How is data encoded in the brain? | Superificial awnser here : We don t know a lot about how data is stocked in the brain. There have been numerous theories but the most used one is the fact that new synapses form which preserve the signal the neurons once send. It can be exampled as : the synapse takes a picture of the info that once traveled trough it and can now send the same info as before without the stymulus. You remember a smell because once the feel of the smell traveles trough some neurons they captured the feeling in a new synapse. The way the brain discriminates between the synapses is weird and that's why a smell/taste can make you remember something completly random , it actives a neuron with a memory synapse. However, the brains uses data without encoding it . A lot of our brain works as a If/If not system much like computers. The data is encoded in the form of the Voltage intensity send from the receptors to the neurons. Short : Brain stocks feelings - > feelings are encoded as different Voltage intensity . | You might need to be more specific on this question. Are you talking about human memory, in our brain? Or are you talking about memory in a computer? In which case, do you mean short-term memory, known as RAM, or long-term memory? |
Why is gross income considered for loans, applications, etc., when net income is truly reflective of ones true income? | In the USA, there's a number of ways you can have money taken out of your check before you get it which would reduce your net income for the check but you'd get the money back at some point. One way is through health insurance savings plans that go into a card that you can use to pay for prescriptions or office visits. You can also have additional money taken from your check that's paid with your taxes that you'd get back as a refund later. Ten people who all made $75,000 gross could all have very different net incomes so it's not a reliable method to base things on. | It's hard to explain to the IRS a mortgage off of no reported income vs. paying a landlord who doesn't ask questions cash. |
Why are nuclear weapons usually detonated in air before they hit the ground? | We don't generally care about blowing up the actual ground so wasting a lot of energy blowing up the ground more is a waste, it's better to blow it up in the air and let the energy spread out and break more things. Nuclear bombs have enough energy it can spread out A LOT and still break things. | Hot air rises, so when a nuclear bomb is detonated near the ground the 'top' of the mushroom cloud forms and begins to rise. The detonation causes the earth under the blast to get very hot, and heat the air. This air rising, [along with cold air being dragged into the hot steam of upward moving air](_URL_0_), causes the crown of the mushroom to grow in altitude and volume. [Here is a schematic drawing of the airflow inside a mushroom cloud](_URL_1_) |
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