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7k2932 | How do immunosuppressants work? | I've just gone on Azathioprine and been feeling worse because of it. But it got me thinking: what does it actually do? Come to think of it, what actually is your immune system? We talk about it so much but never in any depth. | Biology | explainlikeimfive | {
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"Immune system refers to various specialized cells (T cells, B cells, Natural killer cells, among others) that recognize and attack foreign antigens (bacteria, viruses, fungi etc.) As these cells are formed they go through a process that ensures they will only recognize and attack these foreign invaders and not your own cells. In a healthy individual, if they fail this process they are destroyed before they can go out and cause damage to your body. In individuals with an autoimmune disorder, there is generally a failure somewhere in this process that allows these cells to become active and attack their own cells (or in the case of an organ transplant, there are now foreign cells implanted in your body but you obviously don't want your cells attacking them). So the role of immunosuppressants is to prevent your body from forming these immunity cells at all or otherwise limiting their function. This obviously leaves you open to attack from any sort of bacteria/virus that may enter your body. These drugs can also affect some of your non immune cells which leads to some of the side effects that go with these drugs. Actual ELI5: Your body creates an army of cells that are trained to recognize and attack other cell armies if they invade your body. If you have a soldier or group of soldiers in your army that skips through this training, he may start attacking your own kindom/citizens. This is obviously bad so now you need to bring in the immunosuppressants to simply clear out your army to prevent it from causing any more harm. While you are open to attack from the outside invaders, you at least don't have your own soldiers causing as much damage anymore."
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7k2hsq | Why exactly is it that latent psychoses can be triggered by THC/marijuana use? | I'm just interested in whether there's any kind of medical/scientific explanation for this. Is it common for psychosis to be triggered by any mind-altering substance in general, or is this something specific to THC/marijuana? | Biology | explainlikeimfive | {
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"This is something of a myth. THC won't precipitate clinical psychosis in otherwise normal people with no history of such problems. Excessive doses of TCH can cause anxiety and paranoia as side effects and in people who already have anxiety issues, this can cause panic attacks. Anxiety as a side effect is fairly well documented, as far as I know. In people who already have issues with delusional thinking this can't be a good thing. But I wouldn't recommend such people to use any kind of psychoactive substances recreationally, period."
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7k2kxh | How do programmers code chess-playing computers to make mistakes? | Technology | explainlikeimfive | {
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"You don't specifically code it to make mistakes. You code it so it doesn't pick the best move. Chess programs work by testing out a large number of moves into the future and assigning points generally based on how many pieces it is able to keep and how many pieces it is able to capture from the opponent. On \"Easy\" mode, the computer just won't look as many moves into the future, or won't pick the best possible moves out of all the possibilities it found.",
"Chess isn't a \"solved\" game; there's no known sure-fire path to victory. This means your chess machine can make mistakes because it's hard to tell what a mistake even is, even if it's playing it's best. It's not like naughts and crosses where you intentionally have to not play optimally if you don't want a 100% win rate. For an actual answer, a chess engine typically looks a certain number of turns into the future, computing all/the most likely options and deciding which one it will take. To limit a chess engine you can simply limit the number of turns ahead it can look. It's currently impossible to look through all possible moves to the end of a game, so this limit exists anyway and you just have to lower it. Another way to \"weaken\" a chess engine is to change the way it \"scores\" a move. I touched on this earlier when; there's no objective way to say one move is better than another for any two arbitrary moves. You might be able to say \"moving your queen in a place where a pawn can take it is an objectively bad move\", but it's a lot harder to come up with a way to compare any 2 given moves. A simple method would be to say that every piece is worth so many points (1 for pawn, 4 for bishop...) and see if any moves will make the opponent lose more points than you. This is a very simple one with obvious flaws. So you come up with the best way of evaluating a move that you can think of, and let your chess engine use that. For an easier setting, you make it use a worse way of evaluating moves. Lastly, you can have the engine work out the best 10 moves and then pick randomly from those, perhaps you weight it so that it's more likely to pick the best ones on \"hard\" and less likely on \"easy\".",
"Most typically they are simply told not to look far ahead. They can also be told to randomly pick from among the top few moves instead of the single highest-rated move.",
"The algorithm works by trying a selection of moves, and using rules to determine a score. It then chooses the highest scoring move. If you add a random number to each score, then the computer will still usually make the best move, but occasionally make the second or third best move. But will still have a bias towards the better moves."
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7k2lxt | How can Disney comfortably afford acquiring Fox for 52 billion dollars? | Economics | explainlikeimfive | {
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"Don't think of it as disney losing 52 out of its 90 billion dollars. They're getting what they think is at least 52 billion dollars of value. If I have $25,000 in my bank account and I buy a $200,000 house with a mortgage, would people say I have serious financial consequences for doing so? Not really. I have a $200,000 house. It has value. How long will it take to get that back as liquidity? Make a dozen movies. You can now put the X-men in with the Avengers like things are supposed to be. They can now make a TON of films that they couldn't before, all now matching up with comic book continuity instead of having to write around the characters they weren't allowed to use.",
"Have you seen the box office success for their recent movies? I don't think Disney is in any financial trouble. We throw money at them in the masses.",
"It's not exactly spending all that money. It's issuing new Disney shares and giving those to Fox's shareholders in return for their Fox shares. So after the transaction, Disney owns Fox and the people who used to own Fox now own about 25% of Disney. That sounds like a bad deal for all the people who used to own Disney shares because they only own about 75%of Disney now. But of course Disney just got bigger and it's now worth more, so owning a smaller slice of the bigger pie works out OK.",
"Disney isn't spending cash, rather both Disney and Fox shareholders will now be shareholders of a combined Disney/Fox company (that will still use the name Disney). So Disney issues a bunch of new shares. Balance sheets are intended to measure the worth of a company, but brands are hard to show on a balance sheet, and provide a significant part of the worth of a modern company. How many people would buy a soda that tasted very similarly to Coke, but wasn't Coke at the same price as Coke? So in this case, the $90 billion in assets doesn't really measure the way that Disney will purchase Fox, because they're using their $170 billion in market cap to buy Fox (the resulting company will likely be worth about $220 billion).",
"Disney has a lot of money. Disney isn't burning $52B in front of the building, they are giving people who invested in Fox money and Disney stock which is worth $52B today. Those people have to decide for themselves if Fox was worth $52B, which it seems most of them agree with Disney. Disney spent $52B to be Disney + Fox. They have less cash but more stuff. They think they will be able to operate better and make higher profits. Given their plans for a streaming business to compete with Netflix, they might be right. It's not ABC+Disney+Espn was looking for something that starts with \"F\". (If it were, there would be lots of concerned people at Google.)"
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7k2ow2 | How do owners or CEOs of companies pay for things if all their value is tied up in equity/stocks of the company? | Economics | explainlikeimfive | {
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"You can sell your stock, of course. Or you can borrow against the equity you have (and even against future vesting and compensation).",
"Stocks are easy to liquidate. I can go into my investment account and sell $100k of stocks right now and it'll settle and available for cash out within 3 days."
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7k2y7o | Why do people learn differently, i.e, by hearing, by visual, and by touching? | In my 4th grade class, I remember my teacher asking how we as a class learned. I remember being in the minority for people who learn by watching, I think only two other kids raised their hands. Does this change over time and why is hearing the most common? | Biology | explainlikeimfive | {
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"They don't. It's just an old myth. > There have been systematic studies of the effectiveness of learning styles that have consistently found either no evidence or very weak evidence to support the hypothesis that matching or “meshing” material in the appropriate format to an individual’s learning style is selectively more effective for educational attainment. Students will improve if they think about how they learn but not because material is matched to their supposed learning style. URL_0"
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7k2zr1 | Why is head trauma related fuss is centered around football? | There are other full contact sports like roller derby, lacrosse, rugby, water polo, kabaddi, hurling, hockey etc, that in many they don't wear any protective gear, why is only american football causing such a fuss? | Biology | explainlikeimfive | {
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"While the other posters have gotten it right, I'll add one more thing here. While other sports have contact, very few have the _frequency_ of contact like American football does. There can be an average of 70 plays, which means that each lineman is hitting their counter part 70 times over the course of the game. When you factor in number of games, that is over 1,000 hits per season (not counting practice). No other sport comes close to that many hits per season (even boxing). Since it is theorized that CTE is caused by repeated hits as well as hard hits, it makes sense that football has a higher rate of issues",
"I believe it is because American football wear helmets which makes it easier to slam into other players but this jostles their brain. These others sports don't have helmets so it's not even part of the strategy to headbutt people. Kind of like how [boxing gloves increase head injuries in boxing because before the advent of the gloves, boxes would not punch for the head in fear of hurting their fists]( URL_0 )."
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7k30bc | What is a bubble in investments and why do they occur? | Economics | explainlikeimfive | {
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"A bubble is when assets are priced higher than their underlying value. This is typically fueled by speculative investing or over-zealousness - basically, too much money being invested in the asset which causes prices to rise too fast. They are tricky to predict, because you can only really tell something was bubble when the bubble pops - the asset prices drop back down to normal levels. A good example of this was the housing bubble. Housing prices typically rise, to they have always been seen as good investments long term and banks were happy to give out mortgages to people for them (since it was easy to just sell the house and make your money back in case of default). The bubble happened when the banks gave out _too many_ mortgages to people who would have trouble paying them back. This resulted in a lot more people trying to buy houses, which drove prices up. This lead to larger mortgages being issued, which drove prices up even further. It was a bubble caused by too much money in the housing market. When people started defaulting, the banks couldn't sell the assets at the high prices anymore, so prices fell, which caused more defaults. The bubble popped. This is overly simplistic, but you get the idea."
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7k3fl0 | Why does earth rotate the direction it does and why doesn't it rotate the way Venus does? | Physics | explainlikeimfive | {
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"The leading theory is the solar system spins in the direction of the initial angular momentum of the dust cloud from which we spawned. As for Venus, we believe it was struck with a planetoid that drifted into it's orbit and position, striking it so hard and at an appropriate angle the rotation about it's axis was knocked into the opposite direction."
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7k3fu1 | How do neutral countries like Switzerland not get invaded by other countries? | Other | explainlikeimfive | {
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"Switzerland isn't just politically neutral, they're in the middle of inhospitable mountains that will crush your army if you try to invade Switzerland gets to remain neutral because everytime someone says \"We should invade Switzerland!\" someone pulls out a topographical map, points to the big spikey area in the middle of europe and goes \"Fuck that! We'll go around!\" The Swiss have secret bridges, tunnels, forts, and even air bases hidden among the Alps. Any attempt at invading them would result in them pulling back, breaking the infrastructure, and poking the back of your supply lines leaving your army hungry, cold, and trapped in inhospitable enemy terrain Fuck that! Let's go around",
"Switzerland is protected by good mountains and the fact that every adult male is an army reservist. They keep military-grade rifles in their homes, just in case. Other countries try to just stay out of the way, or try to ensure that there is a balance of potential enemies/friends that would help them if one of *their* enemies tries to invade. One last category is countries that have little resources or strategic value. Their neutrality is preserved by not being worth invading.",
"Every country will have different circumstances, but in Switzerland's case, it's a mixture of historical tradition, and strategic considerations. When Switzerland revolted from the Hapsburgs in the 15th century, they gained a great deal of independence, but stayed within the Holy Roman Empire, meaning that anyone that attacked them risked a war with the other German states. At the same time, in the wars that led up to their independence, they developed a fantastically effective fighting style, and most of their neighbors, (France especially) figured out that hiring them as mercenaries was much more productive than trying to conquer them. So they were able to enjoy several centuries of independence, which was formally recognized at the Congress of Vienna that concluded the Napoleonic Wars, which was generally respected by the other European powers during the 19th century. As far as strategy is concerned, it a small, mountainous, (and until the post-WWII era, fairly rural and poor) with a strong tradition of independence and citizen militias. Invading Switzerland would be a very costly proposal for little gain.",
"Some neutral countries get invaded, some do not. The UK attacked neutral Denmark during the Napoleonic Wars. Belgium, Albania, and Luxembourg were invaded in WWI. The UK invaded neutral Iceland and the USA was neutral before Japan attacked them during WWII. Some neutral countries, like Switzerland, Portugal, Spain, and Sweden, were not attacked. In some cases, leaving neutral countries alone is the better strategy. If there is nothing to directly gain by attacking a country, it is best to avoid doing so. Also, a country can officially be neutral, but still support your cause. You can trade freely with a neutral country, and if the enemy doesn't invade, then that trade can go on uninterrupted. In the case of Switzerland, an invasion is a bad idea. Only in a war between France and Germany does an invasion of Switzerland become a tactical advantage. However, doing so would be suicidal. Since Switzerland has an official position of neutrality, their entire military doctrine is based on defense. All major roads, rail lines, bridges, and tunnels are rigged with explosives. They are experts at using their mountainous terrain in a defensive posture. Swiss men are conscripted into the armed forces, and they keep their weapon when discharged, which means a larger portion of their citizens are trained and armed. During the World Wars, an invasion through Switzerland might eventually have become successful, but at a huge cost of personnel, resources, and time. It would be easier to find another way. Also, Switzerland is the banking capital of the world. If country were to invaded, they might find that their money might magically disappear.",
"Neutral doesn't mean that they'll just sit there and say \"What? You're coming in? Oh, alright. Here's the keys to the country, the bins are collected on Tuesdays.\" Switzerland has national service, and a fairly large military as a result. What the Swiss won't do is wade into a conflict between two other nations, but you can bet that they'll be there defending themselves if another nation comes in. Equally, you can bet that their neighbours aren't particularly keen on seeing them invaded, either. Occupying forces have, historically, had a habit of moving on from the last place they took over and moving into other countries. If Switzerland got invaded, their neighbours and possibly their neighbours' allies would be tooling up, ready to overthrow the invaders.",
"I think you're misunderstanding the term neutral to mean pacifist or something. If they were invaded they would defend themselves just like any other nation."
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7k3nae | How does the human body convert the chemical energy from food into the electrical energy needed to power our muscles? | I know very little about biology, but I'm not aware of any tiny biological turbines within our bodies that can somehow convert chemical to electrical energy. So how is the conversion made? | Biology | explainlikeimfive | {
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"> I'm not aware of any tiny biological turbines within our bodies that can somehow convert chemical to electrical energy. You're sort of on the right track, but have things the wrong way 'round. Electricity itself isn't used to power our bodies, but a difference in 'electrical charge' is used to convert some chemical energy into another type of chemical energy. I'll try and give a run down of energy production to hopefully explain (but it's a little difficult without diagrams!): The energy your body needs is stored chemically in a molecule called called ATP ([adenosine triphosphate]( URL_0 )). ATP is what all your food is mostly converted into when you eat - and when stored as ATP, it can be transported and used where and when it's needed, instead of having to use that 'food energy' right there and then. The process of converting the chemicals that make up your food - say, glucose - into ATP is fairly involved, taking place inside your cells in an [organelle]( URL_1 ) called the mitochondrion (which are often called the 'powerhouses' of the cell; where your ATP energy is 'made'). The process itself involves stripping glucose free of electrons. The energy these free electrons have is used by proteins in the mitochondria to pump positively-charged hydrogen ions (H+) from one mitochondrial compartment to another. Essentially, this is electricity within a cell - you're creating one compartment full of positive charge, leaving the other with a relatively negative charge. All these positive H+ ions crammed in together *really* want to flow back into the negatively charged area whence they came (opposite charges attract) - but they can't. The only way to do so is by flowing through a specialised protein channel called [ATP synthase]( URL_2 ). This is what the lil' turbine is! Acting a bit like a water wheel on a river, the flow of H+ ions through this channel spins a part of ATP synthase around, helping it form ATP. **In simpler terms:** your food is broken down into teeny molecules, made up of different atoms, with atoms being made up of + charged protons and - charged electrons. At somewhere along the line, these electrons are taken away, and their energy is used by proteins to move the remaining + bit into a sealed bag. The charge difference between the + inside and - outside forces the + bits to rush out wee holes in the bag, towards the - side. These holes have turbines attached that spin with the flow, using the energy from the current to make ATP. So you could sort of say the cell basically turns 'unusable' chemical energy into electrical energy into usable chemical energy again! Of course this is all *extremely* simplified and as a result misses lotsa' stuff and is slightly misleading (there's a lil' physical energy used in the actual making of the ATP etc.), but hopefully explains things ELI5 enough to perhaps make things a lil' clearer?"
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7k3t2m | Why is it easier to parallel park in reverse rather that forward especially since it’s easier to see in front of you? | Physics | explainlikeimfive | {
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"It's because of the way the wheels are set up. \"Most\" (almost all) cars have front wheels that turn, which means that your turning radius when going in reverse is different than when going forward. Additionally, the direction of turn is swapped making alignment easier when backing in.",
"First you need to put the non-steering wheels close to the curb, then you can cut the steering wheels in to the curb.",
"Your front wheels can turn, your back wheels can't (for most cars!). That means that if you go in forward, you have a much harder time turning your back half - you need a good amount of room to go forward and park evenly, parallel to the curb. But if you're going in backwards, since the front wheels turn, it's possible to back in at a sharp angle, swing the front around, and end up parallel to the curb, or close to parallel, so that you can adjust in a small amount of space. So it works out much easier."
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7k41zc | Why do most children seem to go through the same interest phases? | Biology | explainlikeimfive | {
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"I think one of the best hypothesis is that the developing mind likes to explore its world in stages. Babies, children, and young adults usually progress through understanding concepts like \"recognizing a ball is not gone because it is behind a box\", \"realizing your parents aren't dead if they leave the room\", to stages such as understanding fundamental principals of movement and shape (as seen in cars), until they arrive at conceptual understanding. From simple structures (like cars), it is easy for them to begin to imagine new things, now that they have a foundation of what a car is. Then they expand through their desire to learn and through creativity. These objects are simple, and so it is not usually seen that children can fully grasp conceptual things (such as science, math, politics, etc.) until later in their developing years. Even though we see youth brain development at different rates, it is almost impossible for them to formulate unique opinions on conceptual topics, so they stick to the basics and go from there. So, they like things based on what they know. The starting new interest is usually based on what they know, and what they know is just a subset of what they've been exposed to. This doesn't apply just to cars, trucks, trains, and airplanes, but whatever is similar-and-different from their base knowledge. Why it seems like everyone you know had a truck-car-train phase is based on your culture. This is the foundation for teaching your children fundamental knowledge."
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7k4778 | what is political capital? | Other | explainlikeimfive | {
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"It refers to potential influence, things like favors, willingness to give you the benefit of the doubt, goodwill, etc. It is often useful to think of it as a resource that can be exhausted. If you are trying to garner support for your big new project, it might not be the right time to expend your political capital to get a better parking spot. It has similarities to the concept of picking your battles.",
"Political capital can be described as the loyalty which some people feel toward any specific politician or political party. If some group of voters has for whatever reason come to the conclusion that someone is working on their behalf and doing good things for them, they will then support that person or that party. Even if that person then happens to do something that they do not like, they still have to weigh that objection against the loyalty that they otherwise feel. So a politician can, metaphorically, spend political capitol by offending his or her supporters but he or she will not necessarily lose all support. No one is expected to be perfect, and imperfections can often be forgiven. Still, political capitol can be spent, and at some point it can run out. You can forgive something, but you cannot necessarily forgive everything. Loyalty is usually not absolute."
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7k59ql | What happens to your body during and after competitive eating? | Biology | explainlikeimfive | {
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"I guess what I'm really curious about is the process right after the binge. Do they get super constipated? Do they force themselves to throw up? How long their uncomfortable for?"
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7k5ahu | How does a pharmaceutical company come up with new drugs? Do they just try various chemicals on animals until something shows promise, or is there an approach that's more "targeted" than that? | Like let's say I want to develop a better antidepressant. Where do I start with that, if I'm the R & D department? | Biology | explainlikeimfive | {
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"There are generally 2 main methods of drug discovery. In the first, you figure out a way to test new chemicals in a chemical method (like does compound X kill bacteria at very loe concentrations and not kill human cells at all). There is a large amount of testing done, and then it is moved to an animal model (usually mice). Tons more testing in several different animals and lots of human cell lines. Much later it will be tested on super low doses in humans and follow the rest of the FDA drug approval process. The other takes a slightly more informed view. If we know that a disease is caused by some sort of chemical marker or protein in the body, we can use computers to calculate if the chemical will affect that chemistry in the body. If it passes the computer test, it can move on the the chemical tests and then through the rest of the cycle. Basically, yes, we throw a bunch of chemicals at a problem until one looks good, but we do a lot of testing before we ever move to animal studies. A drug discovery person could (theoretically) work their entire life and never have a compound move from chemical tests (assay) to animal model. This is why it is so expensive.....IT IS FREAKING DIFFICULT!",
"Yo ho ho! Yer not alone in askin', and kind strangers have explained: 1. [ELI5: How do pharmaceutical companies create new drugs? ]( URL_4 ) ^(_5 comments_) 1. [ELI5: How are new Pharmaceutical drugs \"designed\"? ]( URL_3 ) ^(_2 comments_) 1. [ELI5: How do pharmaceutical companies develop drugs without knowing the chemicals function on the body? ]( URL_6 ) ^(_4 comments_) 1. [Reddit - explainlikeimfive - ELI5]( URL_2 ) ^(_._) 1. [ELI5: How do we produce and synthesize new drugs? ]( URL_1 ) ^(_1 comment_) 1. [ELI5: How are new drugs synthesized/discovered? ]( URL_5 ) ^(_3 comments_) 1. [ELI5 How do scientists create artificial drugs/chemicals ]( URL_0 ) ^(_12 comments_) 1. [ELI5: How we know what a medicine will do when we create and test it. ]( URL_7 ) ^(_8 comments_)",
"Many drugs start with a known 'skeleton'. Take the classic opioids/opiates as an example (morphine, heroin, codeine, thebaine, etc). They all have a core structure that is the same. So you take that structure and 'join things' to it (or maybe remove things). A methyl group here, a hydroxyl group, there (aka - functional groups). Now you have something that is likely to behave in a similar fashion, but you don't know how strong/effective/toxic it may be. So you do a huge amount of testing to find out, well before you ever give it to a human. That's a really simplistic explanation, but you get the idea.",
"Sometimes already made drugs can be found to have more purposes than originally thought, too. An anti-seizure drug being used specifically for the mood stabilizing properties it also has would be an example of this. If you’ve heard the term of a medicine being used “off-label” that’s what it’s referring to. Or, an already made drug could be found to have somewhat of an unexpected effect, and then research takes place for a way to take advantage of that effect. I’m sure there’s more examples but the one that’s coming to my mind right now is Botox. It works cosmetically by relaxing the muscle which in turn smooths the skin above it. Some patients reported that afterwards, they got fewer migraines. So of course this was studied, and now if you suffer from chronic migraine and fit some certain criteria a treatment option is Botox all over your head and neck, though admittedly at a much higher dose than used cosmetically. Nobody is completely sure how migraines work, but tight muscles apparently play a part. Anyway sorry, my point is that I thought you may have been interested in how medicine can continue to evolve after they’ve left the pharmacy too. If I have made any mistakes in this comment, someone please correct me.",
"SO I KNOW THIS ONE ...SORT OF First, you have a disease or condition you are trying to find a drug for. Take.... for example, non-small cell lung carcinoma. After a lot of wet lab analysis and genomic analysis, it's found that certain receptors in a cell that control certain functions (for example, something called epidermal growth factor) has a lot of mutations in it for people who have NSCLC. Some dudes in a lab will then test to see what kind of compounds will block the receptor for epidermal growth factor, to stop the overproduction of it, because that is what mutations typically do. Either too much stuff is made by these cell receptors or too little is made. In the case of NSCLC, too much is made. So a compound that can lessen the amount of epidermal growth factor being made by the cell is called an inhibitor. So they run some structures of the part of the epidermal growth factor receptor that controls switching it \"on\" or \"off\" through a database, usually the Protein Database (which also happens to be housed at my alma mater, heyo, go Rutgers University-New Brunswick!), and find compounds that are similar in structure to the receptor, but will turn it \"off.\" Then they try to find analogous structures in drugbank which is another database. Then they do a lot of in-silico analysis (on the computer) through simulations and programs like Chimera, or Argus Lab, to isolate what kind of compound is needed. It's kind of complicated, so I won't go into all of that. Then they have to create the drug, and put it through pre-clinical trials, so on mice, typically. So the toxicity is measured in mice, and the efficacy of the drug (does it help turn this receptor thingy off or nah??). After it's safe and effective in mice, we crank it up to phase I clinical trials, so that's usually just testing the half life of the drug and most importantly, the safety of it in humans, but in small doses. Then there's a few more phases to see what the safest-highest dose can be. And then extensive testing in what we call PK/PD or, pharmacokinetics, pharmacodynamics -how a drug affects an organism, and how an organism affects the drug- (I should add, this is also done in the mice model testing too). And then, if a lot of people can tolerate this drug and benefit from it, it has to go through an FDA approval (lots of paperwork... and time), and then it needs to go through a lot of marketing stuff to get it into the global market. It can take up to 12 years for a drug to be taken from discovery all the way to development, and finally to marketing. It's a process. But a necessary one, I guess.",
"They know the general receptor structure they're trying to effect, analogues will have varying levels of effectiveness once broken down by the body. Heroin is converted to morphine for example",
"Do people still wander around the jungle after talking to the local shaman for potential cancer drugs like that one movie?",
"It's not quite that random. There is much \"basic\" research that goes on at universites well before pharmaceutical companies are involved. That provides a good understanding of which molecular pathways can be targeted and with what kind of results.",
"Fundamental research is very important. New discoveries in how diseases work, such as molecular pathways are the starting point of new drugs. If you understand diseases you have at least some hope of developing effective treatment. Otherwise it s just a blind game of hit and miss",
"In true ELI5 mode: some chemicals that occur naturally in the body but are known to be too low in a sick person, can be mimicked with an artificial version created by chemists. An example would insulin for people with diabetes. On the opposite side, some sick people have too much of a chemical and artificial agents can be created which reduce or nullify some of the excess chemical to bring the concentration closer to the range expected in a healthy person.",
"You're probably asking about computational drug discovery. Though you can concoct umpteen different drugs and throw them at animals and see what sticks, a cheaper and more effective method is to try to narrow the field first. One method is protein-ligand docking. You want to find a chemical that will sit nicely in the \"keyhole\" of a particular biological structure. Fitting in this keyhole will either start a chemical reaction that otherwise wasn't working, or block another chemical from fitting in that keyhole and causing problems. The trick is to find the shape of the keyhole through something like x-ray crystallography and then once you've got the 3D shape of that, start computationally trying to build chemicals that'll fit that shape. The latter's the hard part. If you can produce software where you can take a 1D protein sequence and predict the 3D structure it folds up into, then the Nobel Prize is in the post, no questions asked. The computational part will try to narrow down which chemicals produce something more or less the right shape, but with all the best computation in the world, we still need to actually produce the drugs and test them before we know if they a) work and b) don't also cause side-effects.",
"A lot of good answers here have addressed how drug developers choose disease targets and develop compounds into approved drugs, perhaps another dimension to the question is \"why don't drug developers just test things on animals (or people) until they work?\" In theory, the best way to determine if a drug works is to give it to people and observe the results. However, chemists can go through thousands of variations on compounds before they find one that is both safe and effective, which would mean you would need tens-of-thousands of people willing to be likely poisoned until a viable candidate was discovered. Not going to happen. So how about animals? There are a lot of animal models for human diseases, which researchers use for testing drugs. These models are not always precise, and mouse physiology has obvious differences from humans', so you need to experiment on a lot of animals in order to generate results that you can say are reasonably accurate and predictive of what a compound would do in humans. This takes time and can be quite expensive. The quicker and cheaper option is to experiment on cell lines or even use computational models to predict compound activity. Typically, a drug program will take years of working through hundreds or thousands of compound variations before they are ever used on a whole living organism. Tests will start with methods that are quick, cheap, yet inaccurate and slowly work up to tests that are more accurate, expensive, and time-consuming. Even with all of this work, most compounds that make it to clinical trials fail because the drug is either too toxic or show any significant benefit.",
"You may find this post interesting regarding how much it costs to research and develop a drug URL_0 Edit: copy/paste from /u/MyPenisIsaWMD post in 2016 Hi, I make drugs for a living. Drug development is the most high risk/high reward industry possible. It costs roughly 2 billion USD to take a drug from conception to market. The vast majority of drugs never make it to market. Each of those failures costs some fraction of 2 billion USD. Many of those failures are weeded out only at the end when all of that investment has already been made. For those failures, the company makes back 0 of it's investment. It's not like a phone that doesn't sell as spectacularly well as hoped. It's no product at all. You can't even learn much from those failures. It's years of people lives (sometimes 10 or more) and huge amounts of money that just evaporate. It's crushing. This is why the drugs that work have to be expensive. They have to pay the company back and more for all the failures. Interestingly, most companies making drugs aren't huge. Most are quite small: Here's an anecdote that represents a typical trajectory of a drug in development. It's an entirely true story but the numbers are best approximations: Small company starts with idea, raises 10 million from venture capital, hires 5 people. 99 of 100 of those investments go nowhere, so the investors want a HUGE stake to make it worthwhile. At least 51%. You'd be reckless to ask for less. But hey, you now have a company doing innovative science where before you had nothing. So anywho, they lease lab space and equipment and develop the idea and it shows promise. Round 2 of financing comes in, another 50 million at the cost of another 30% stake, they hire 30 more people, lease a larger space and buy more necessary equipment. It's getting to be an expensive company to run and it so far has nothing to sell. It starts to 'burn' money at a rate that means the doors can only stay open for maybe another year. The idea continues to show promise. It works in cells, it works in mice, it works in primates, it's time for clinic. Round 3 of funding comes in with 100 million, and that costs 15% of the remaining stake. Company hires 20 more people, this time mostly bureaucrats to set up a proposal for an 'Investigational New Drug' application. This is what you need to convince the FDA to allow you to start clinical trials on humans. Right now, the original owners retain only 4% of the original stake. So, time for clinical trials. Phase 1 begins with 30 healthy adults. This is just to show that the drug is safe. It costs 10 million USD. The company has zero profits so far and has been paying 60 people for years, so it has to pay for this cost by leveraging 3% of the final stake. Eventually, the 'burn' rate means that it has to fire 90% of their scientists as they can't afford salaries anymore. That's OK though, because this startup has succeeded. You see, Phase 1 clinical trial pass (the drug is safe) and it's onto phase 2 (which asks 'is it effective?). This costs 40 million USD more but no more money is left. What to do? Only one option. The investors who now control 99% of the company decide to sell everything to a company like Novartis/Merck/GSK, etc. The company sells for 500 million USD on the expected promise of the new drug. Original founders walk away with 5 million USD due to having a 1% stake. Everyone else is out on their ass looking for a new startup. This is considered a HUGE success in the startup world. It's what everyone hoped for. Now, Merck or whoever takes over development of drug X. Drug passes Phase 2 but fails in Phase 3 Trials. And that's how you lose 1 billion USD over 10 years with 100s of cumulative years of human work down the drain. THIS is why developing drugs is expensive and THIS is why the drugs that work are expensive. To anyone saying that Universities should make drugs instead of industry: There are very, very few universities that could afford this. Harvard maybe. Most universities would spend their entire endowment on a 9 to 1 shot. Universities like bonds for a reason. You don't play roulette with your endowment. This is a job for people willing to risk billions. And this, my friends is why drug development is so centralized in the US. Fucking cowboy investors are the best route forward here. And for those who think this is cynical, please recall that for the actual people who founded this company and for the scientists doing the research, they are most often driven by a desire to cure horrific diseases and change the world. The money aspect is a necessary evil that good people need to navigate. Consider that a typical PhD scientist makes about 1/4 as much as a physician and spends a similar amount of time in education (13 years for me from BS to end of postdoc). The people actually researching new drugs are doing it because they are passionate about human health. Not because they are 'shills'."
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7k5eyj | How do snow removal trucks not scrape up the streets they plow? | Other | explainlikeimfive | {
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"Most plows have small slidey things or wheels behind the scrapy parts that keep it from getting too close to the ground. This doesn't always work."
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7k5ft5 | Communication Protocols. What are they, how do they work and why is there so many different ones? | Technology | explainlikeimfive | {
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"A \"protocol\" is just a set of rules for how to communicate. A good example of a protocol would be answering a phone before there was caller ID. * Phone rings. This is a signal to pick up the phone. * Callee picks up the phone and indicates that they are listening. (\"Hello?\") * Caller identifies themelves. (\"Hi, this is Alice.\") * Caller asks for the person they wish to talk to. (\"Is Bob there?\") * Callee attempts to find that person (\"This is Bob.\", \"Hold on, let me find him.\", \"He's not here right now.\") * If the intended recipient of the call can be found, the two parties continue the conversation. * If the intended recipient cannot be found, the callee takes a message for the intended recipient (\"Can I take a message for Bob?\") When computers send messages to each other across a network, they need a set of rules to follow similar to the ones above so that they can understand each other. If both computers follow the same set of rules, then they can successfully transfer information from on to the other. The reasons there are different protocols is because different circumstances require different kinds of communication. We do this as humans, too. Not everything can be done via text message. Sometimes it's easier to write an email, make a phone call, or just go talk to someone face to face. From a human perspective, each of these has a different \"protocol\" associated with it. When you send an email, you don't need the \"Hello, who is this\" exchange that a phone call might have. A phone call doesn't have paragraphs, the way an email does. Another reason there are many different protocols is because often one protocol doesn't solve the whole problem. Loading this web page requires the use of several protocols all working together. Off the top of my head some of the protocols likely used while transmitting this web page to you were Ethernet, IP, TCP, HTTPS, and TLS. Each of these solve part of the problem of communicating across a computer network. Ethernet allows one computer to talk directly to another computer over a wire connecting the two. The path from Reddit's servers to your computer goes through many such direct connections. IP (Internet Protocol) is how the message finds its way through those many hops along the way. Messages sent with IP are very small, and large web pages need to be broken up into multiple smaller messages, and then reassembled at the other end. TCP (Transmission Control Protocol) is how that happens, like if someone sent you a novel ten pages at a time, and you had to reassemble the pages into the full book. TCP can deliver any sort of message, but a protocol like HTTPS is a set of rules for the structure of that message. TLS is a protocol used to encrypt and decrypt the message at both ends. So, these all do different things and work together."
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7k5iz3 | Why is there no single solution formula for polynomials of the 5th degree and higher? | We have a quadratic, cubic, and quartic formula, that you can just plug any polynomial into and get solutions. However, above the 5th degree, there is no single equation like this to solve functions. I've heard of the Abel–Ruffini theorem, but I just dont understand why it's true. Is there a simpler way to explain this? | Mathematics | explainlikeimfive | {
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"There are formulae that can give the solutions to 5th degree polynomials and higher. It is just that their solutions cannot be expressed algebraically, using only addition, multiplication, and roots. You have to use new operators, such as the Bring radical, to express those solutions.",
"The reason is because of what we mean by a \"formula\". The formulae for the solutions of second, third, and fourth degree equations involve only the following symbols: 1. The coefficients of the equation. 2. The four arithmetic operations: addition, subtraction, multiplication, and division. 3. n-th roots (square roots, cube roots, etc). It turns out that there are fifth degree equations for which the solutions simply cannot be expressed using that alphabet of symbols. The intuitive reason for this is: why did you ever expect otherwise? You don't find it surprising that there's no formula for solving polynomial equations using only points (1) and (2), so why would adding (3) suddenly be enough? There's nothing special about n-th roots other than that they happened to be enough for degree 2, 3 and 4 equations."
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7k5w9d | What's after 4k resolution, and when will we get there? | Technology | explainlikeimfive | {
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"8k resolution has been a thing for a long time. Its just not very popular.... why, well frankly, we're really not even at 4k yet in the general market. Very little video content is available in 4K. There's a lot of screens that do 4K, but minimal content. Instead of resolution, HDR is more likely to be the \"next big thing\" for video. 4K HDR is gonna be around a long time. Its really good and has a lot of benefits instead of bumping up to 8K.",
"First let's understand what 4k is. 720 is a resolution of 1280 x 720 for a total of 921,600 pixels. 1080 is a resolution of 1920 x 1080 for a total of 2,073,600 pixels. 4k is a resolution of 3840 x 2160 for a total of 8,294,400 pixels. 8k, the next step up, is 7680 x 4320 for a total of 33,177,600 pixels. You'll notice that the naming scheme changed from 1080 to 4k because companies thought using the bigger number was more impressive. What we know today as 4k should really be called 2k or 2160. As for quality, every time we double the horizontal number and go up a quality step we are actually quadrupling the number of pixels. If TV's don't get any larger more pixels will stop mattering as we already can't see individual pixels anymore at a normal viewing distance.",
"This depends on what you mean by \"when will we get there?\" for the common tech user, it may not advance quickly, as there isn't much demand for higher than 4k resolution. Panels with higher resolution are available if needed, although not in your average market. 4k is excellent, and impressive technology at that, but in many instances, even 1080p is adequate. But there are already 5k panels. It seems to me that resolution will keep getting better, as we demand larger displays with higher pixel density.",
"At the moment the acquisition and distribution of UHD Phase 1 and Phase 2 (4K and 8K for TV) is not widely developed for many reasons. The bandwidth requirements for an UHD are very large and the technology is not really there for the distribution to the home. Whilst UHD Phase 2 (8K) will be the next resolution jump we are still a long way off from delisting it. Tests are being done at the up coming winter games and football World Cup. The next development for home entertainment will be HDR. There are different types of HDR. HLG HDR is being developed by the BBC and is about to be tested very shortly in the UK. The is a type of HDR that’s is compatible with screens with a standard dynamic range. TV’s will start being developed with different HDR standards. Not all standards are equal with some allowing content to be displayed at higher nit rates and dit depths which is what you want as a consumer for a better colour and brightness range. The one standard being developed to look out for is ‘Dolby Vision’. This standard incorporates dynamic metadata. This allows the tv to set the dynamic range on a frame by frame basis rather than an overall range for the entire programme. Dolby Vision also allows a higher theoretical nit rate of 10,000, however only 4000 can be achieved at the moment. This higher nit rate will allows brights to be brighter and darks to be darker. Look out for Dolby Vision in upcoming TV’s",
"6k then 8k? Honestly we have hit diminishing returns when it comes to resolution. Next is HDR and better picture/color like OLED. Then VR?",
"What is the relatable viewing resolution of the human eye? Will these Ks get to a point where it is simply imperceptible to the eye at normal distances?",
"There's literally no reason at all to go above 4k resolution. For most viewers at normal viewing distances, the difference between 1080 and 4k is difficult to resolve. The difference between 4k and 8k would be impossible to resolve. We would get better results visually from an expanded color gamut, increased color accuracy, and better contrast than we ever will from increasing the resolution beyond 4k.",
"We are limited by bandwidth and processing power. Broadcasting/transmitting 4k is trouble enough that it will be a while before we go higher. Things tend to stay in powers of two when it comes to technology so the next logical step will be 8k although we are starting to see more work put into actual quality over quantity which is why HDR is being pushed along with 4k. As most people don't want a TV over 65\" the quality improvement over 4k is extremely small where deeper colours does far more to improve the image quality and allows for the studio/director to produce a truer to their vision final product."
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7k5y7k | The Kesha vs Dr. Luke resolution. And why it wasn't a more influential thing during the #metoo movement | Other | explainlikeimfive | {
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"There are now many individuals, groups and efforts that ask the question \"why now, and not when I/we were experiencing the same?\" It is the way things often are with big social movements. We all know Rosa Parks, but how many know Claudette Colvin? Many, such as our President, think the civil rights movement started with Martin Luther King Jr. and are unaware of the ground work lain the decades before. And I think it is the same here. Kesha (especially her song \"Prayer\"), the documentary made of child sexual abuse of boys in Hollywood, the accusers of Trump etc are some of the ones who did the ground work. Weinstein was the final straw that broke the camel's back, but all the other straws piled up earlier are also important - though we may not be consciously aware of it and they may never get the recognition for it.",
"I'm out of the loop. Can you link me to this issue?"
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7k63y4 | Why do humans have dominant hands? Do other species have dominant sides as well? | Biology | explainlikeimfive | {
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"[Yeah they do.]( URL_0 ) Gorillas, chimpanzees and bonobos are predominantly right-handed while gibbons are left-handed. Orangutans are giving mixed signals.",
"The dexterity of a human hand is absolutely amazing and the work that goes into training this dexterity is far from negligible. When you're doing a task that requires extreme dexterity in your fingers it requires a lot of your brain's CPU. It would be fairly difficult to say be able to concentrate on both hands writing at the same time. Having both hands dexterous offers almost zero benefit. Even in sports you rarely see being ambidextrous as an advantage. Training both hands to be extremely dexterous is most likely a waste on resources for the benefit it offers so only one hand is trained to be dominant. Our ambidextrous ancestors probably were less likely to survive due to the costs than the dominant hand ancestors so dominant hand was the trait that survived.",
"Yup on the other species: Polar bears are all leftpawed. Nobody knows why. Doubt there is an explanation for humans, but hopefully someone comesin and proves me wrong!",
"For the second part: Elephants develop a dominant side in twisting ther trunk. When they are young they do it both clockwise and counterclockwise, however they soon start doing it one way over the other.",
"We *think* that maybe it has something to do with different sides of your brain handling a few different important functions but to be honest nobody really knows for sure. Some animals do have dominant sides, but we don't know what causes it for them either.",
"I'm in no way an expert. All I can do is point out that there are crustacean species that have larger claws on one side. Basically, if it helps you survive to have one appendage that is better at details, and one that is better at broad strokes or strength, those traits continue. It's probably a leftover, and there is no evolutionary pressure to prefer one side or the other. Right handedness is just more likely, due to genes and it already being more common.",
"Ahoy, matey! Yer not alone in askin', and kind strangers have explained: 1. [ELI5: Why do humans (typically) develop hand dominance (right vs. left handed)? ]( URL_1 ) ^(_17 comments_) 1. [ELI5:Why do we have dominant limbs (Right handed left handed)? ]( URL_3 ) ^(_ > 300 comments_) 1. [ELI5: Why do we have a dominant hand/foot instead of using both hands/feet equally from birth? ]( URL_2 ) ^(_ > 2400 comments_) 1. [ELI5: Why is 1 hand more dominant than other? Why can't we use both hands equally? ]( URL_0 ) ^(_21 comments_) 1. [ELI5: Why are we normally either left handed or right handed and not ambidextrous? ]( URL_4 ) ^(_52 comments_)",
"I don't believe we fully understand what makes a dominant hand the way it is, however most animals have a dominant side. Birds for example are more often dominant lefties. In fact, I have an African Grey who refuses to step up on a right hand because if this. I'm pretty sure he feels the right hand can't be stable because he himself is a lefty."
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7k67jf | Why aren’t there any medicines against the flu? And in general, against many viruses? | Biology | explainlikeimfive | {
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"Viruses aren't alive so they're impossible to kill. Bacteria are alive, they have to take in nutrients and have many chemical processes that go on, and antibiotics are chemicals that actively disrupt those chemical processes. A virus is inert, there's nothing to turn off and they don't \"eat\" so you can't make them take in a poison. Viruses inject their DNA into a host cell and then uses your own cell's mechanisms to build more viruses. This is hard to interrupt without turning off the normal operations of your cells which you know, keeps you alive. Many viruses can be protected against via vaccines, which \"teach\" your immune system to recognize the virus and destroy it. Cold and flu viruses are highly adaptable and rapidly mutate to avoid this, so getting as flu vaccine this year only protects you from a small number of flu strains and not from any new mutations of flu. Tamiflu is a drug used to stop flu virus by interrupting the ability for new viruses to exit a host cell, slowing down the spread of the virus inside your body. It's no good to you if you take it after the flu has already spread, and doesn't work against other common respiratory viral diseases.",
"Viruses are extremely difficult to deal with because they can adapt and change. The only real way to stop viruses is to prevent them from infecting in the first place is with vaccination The history of smallpox is incredibly interesting! Even the Wiki page is worth a quick look"
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7k68wp | What are these black spots that mysteriously appear floating on the air? | Other | explainlikeimfive | {
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"drbveqx"
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"So you or your girlfriend have any especially wool-y type clothes? Or do you have a cat that has very fine hair and sheds a lot?"
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3
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7k6b7j | What is IBM compatible PC? | How does it differ from modern PCs? Does Apple Mac' belong to this category? | Technology | explainlikeimfive | {
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"The IBM PC is a literal name of the device that was developed and released by IBM in 1981. [link]( URL_0 ) It was a low-cost computer for a personal use built with generic hardware components, so the market for such devices was quite huge. Because of that a lot of companies started to release their own clones of IBM PC based on the same architecture and similar components. Such devices were often referred as IBM PC clones, or IBM PC compatible. Oh, and it's not \"IBM compatible PC\" since there was and is a lot of different IBM computers. The correct term is \"IBM PC compatible\", which means it's similar to IBM PC device.",
"Back in the day, and by that I mean the 80s, there were a few different brands of PCs that had their own OSes and architectures. Apple was one, IBM was another. IBM compatible PCs were computers that used the same architecture as IBM, and could therefor run the same software. Modern PCs are descendants of the IBM and IBM compatible PCs, but IBM doesn't really do much in the PC market anymore so the term isn't used. Apple and later Macs were not IBM compatible, although now they use Intel chips anyway.",
"In the good old days computers were giant things that you had sitting in a room in big companies and connected what were little more than mechanical typewriters to it in distant places. They were not for everyone. Then computer became smaller and smaller and microcomputers were suddenly a thing. Still rather expensive but suddenly small enough to fit on a person's desk. Some clever people came up with the idea that you could not just use them for work but also at home to do things. And the idea of a home-computer was created. So there was a large variety of computers that were supposed to be small and affordable and used in businesses and in the homes of people who were rich enough to afford them. They were all different and mostly incompatible with each other. Then IBM came into the picture. Or rather some clever engineers at IBM. The company had been (and still is) in the business of selling business large mainframe computers. They wanted to get in on the whole small computers business, but not enough to spend serious time developing stuff for it. So the engineers who were assigned to the project simply put together a small computer from of the shelf parts. At that time IBM usually still made all the hardware themselves from disk drives to keyboards, but the company did not consider this minor project worth the hassle of developing special hardware for it, so the engineers took what everyone could get and put it together for a relatively small, cheap and powerful computer. Thus the IBM personal computer was born in 1981. It was not particularly better than most of the competition but it had the IBM name attached to it and in those days people still believed the saying that \"nobody ever got fired for buying IBM\". They got a small company called Microsoft to license some software called DOS for it and sold the whole thing to customers. Now as I said above IBM normally was in the business of making the whole computer themselves. The build their own computer chips and their own software and their own everything. But for this little project, because of the lack of a proper budget they went with parts that they didn't own the sole rights to. This meant that somebody else could come along and build a computer from the same sort of parts and put the same software on it and have it work the same. Nowadays we sort of expect that a computer bought from HP or DELL or Lenovo will work the same and that you don't have to buy different programs depending on the manufacturer of the computer (except when it comes to smartphones). Back then it was a completely new concept, you could buy a cheap clone of the IBM-PC and run software on it that was meant to run on the IBM-PC. Imagine that! getting something that works as well as an IBM computer without having to pay IBM prices for it! The manufacturers of these computers put labels on them to let the buyers know that they would work just like IBM-PCs and the makers of software made it clear that their software would run on computer that was built to be compatible with the IBM-PC. This proved to be a huge thing because suddenly all these different companies involved could target their products at a single type of computer that was produced by a large number of different manufacturers. And that was not all the parts for these computers could be made by a number of different vendors too. Today we only have Intel and AMD left, but in the early days there were a larger number of chip manufacturers who made chips that worked the same and which would fit in the same motherboards. You also had all sorts of different business making other parts like video-cards and sound-cards or memory chips or whatever you had. Even the software could be switched out to a degree. Towards the end there were a number of OS that worked just like MS-DOS without being from Microsoft. Everything was standardized and everyone could play. This meant that IBM-PCs with their modular nature that everyone could make parts for and that could be upgraded came to dominate the Personal computer market. The Domination was so complete that after a certain point people stopped using the name \"IBM compatible\" because that was the default and only type of PC that there was as far as most consumers were concerned. You Commodore and Amiga home computers just could not keep up with the market dominance of the IBM-compatible PC. Apple was for a long time the only survivor with any sort of market share which was not an IBM-PC . (This despite the fact that Apple's computer were actually called PCs and that their architecture was actually the PowerPC chips made by IBM) To naming convention shifted to something like x86 to mean everything based on the original IBM-PC after the ending of name of the intel chip used in them. At some point people realized that the architecture was usefull enough to build more than just PCs out of it and they started building servers out of IBM-PCs. This further helped to kill of the remains of much of the old type of mainframe computers. At some point about a bit over a decade ago IBM realized they were no longer making much money of building and selling their PCs. they still sold a lot of them but the competition that came from everyone being able to build basically the same thing mean there was not much profit in it. IBM sold their PC business to the Chinese company Lenovo. Several year later they also sold the division that made servers based on PCs to Lenovo. So IBM despite inventing the format today no longer actually makes IBM compatible PCs. But everyone else does. All the normal PCs today are IBM-compatible ones. Even apple switched to the IBM PC compatible format a decade ago. But just as the victory of the x86 architecture seemed complete smaller computers in smartphones using ARM architecture started becoming popular. They appear in phones and even in some tablets and cheap laptops. they also appear in all sorts of small devices that have computers in them from TV-sticks to smart home controller. So while the IBM-PC has won over almost all its old competition, just as it was close to victory IBM stopped making them and a new competitor appeared that is rapidly gaining on it.",
"In the 1980s, there were several incompatible personal computers on the market, IBM, Apple, Commodore, TRS, Timex-Sinclair, Atari, and more. IBM used unpatented off the shelf parts and licensed an existing OS rather than make their own. That meant other companies could make computers that were compatible with software written for IBM PCs, and many less expensive IBM \"clones\" were on the market. This, in part, is what allowed the IBM style machines to win the PC wars. True IBM PC cost a hefty premium and had little to offer over the cheaper clones. Eventually, they surpassed IBM and were more properly Microsoft OS and Intel CPU compatible, but the term IBM compatible stuck. These days they are more commonly just referred to as PCs while other computers are referred to by brand name."
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7k6dhy | In terms of conservation of mass, how does a baby form? | Where does the mass come from to properly develop a foetus and in turn a baby? | Biology | explainlikeimfive | {
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"Ice cream and pickles. The baby is connected to the mother via the umbilical cord, and this supplies the growing fetus with nutrients and oxygen, as well as removing carbon dioxide and metabolic waste. The mother can eat extra food (hence the phrase \"eating for two\")",
"Short Answer: Food. Long Answer: The mother's body works like a surrogate set of organs, performing all the processes that the developing child isn't yet equipped to handle. One of the most critical being the supply of energy and nutrients essential for growth. As the mother eats and drinks, food is broken down into base components and processed by the digestive tract, some of which proceeds to the child. From this comes both the energy and the mass used in the physical act of development, much like how a person naturally converts food into various body components (blood, fat, muscle, etc.) during the course of their adult life."
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7k6ivi | How are 2 people of similar height, weight, and BMI, able to handle the exact same temperature differently; one feeling hot and the other cold? | Biology | explainlikeimfive | {
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"Perception of temperature is not absolute and is based on the difference between the temperature receptors on your skin/mouth/etc and the air around it. You feel cold if the ambient temperature is lower than your shell (outer layer of your skin that touches the air) or core (mouth, nose, butt that can become exposed to the air). This is why when you breathe in through your mouth, the air can feel cold but your skin doesn't. Height, Weight and BMI doesn't account for things like fat percentage. The more fat a person is, the more well insulated they are. Aside from sex, you can also have hormonal differences. A woman tends to have their heat centralised, meaning most of its towards the torso of the body because of child rearing reasons while a man tends to have their heat more distributed, because they don't rear children. These differences tend to be due to fat distribution (women distribute their fat differently) and sex hormones (which also affect fat distribution). Presumably given two identical people on different sex hormones, they'd have different observations of temperature. The major difference is due to thyroid hormones. Thyroid hormones, or triiodothyronine and thyroxine control your basal metabolic rate (BMR) which increases your energy usage regardless of voluntary movement. Basically put, its the minimum amount of energy you use per day. Hyperthyroidism or excess thyroid hormones causes you to have a higher BMR, feeling hotter. Hypothyroidism causes you to feel cooler. Ranges that are above normal, but not pathological (disease state) can cause you to feel hotter than another person. There's also other differences like sweating. Some people sweat more than others and that's due to how much exercise they usually do and genetics. There's also hair on their skin - hair traps heat so more hair means more heat. There's also temperature adaptation. If a person that's used to the cold goes to a hot place, they'll feel hot for about a week until they adapt by sweating more and won't feel as hot any more. The two people might be deferentially adapted to 75 degrees. Muscle is a contributor as well. Skeletal muscle or the muscle that you can use (voluntary) tends to use up energy as well, and its modified by thyroid hormones. But the more skeletal muscle you have, the greater you're going to spend in BMR to keep the muscles functioning. But its usually not that big a difference compared to other factors. Last thing. There's something called idiopathic hyperthermia where a person's body runs hotter for some reason and we don't know why so we pretend its just normal-ish. That can make a person feel cooler in a 75 degree room compared to another person. **tl;dr I realised that this isn't suitable for 5 year olds lol. You feel cold is air is colder than skin or body. You feel hot is air is hotter than skin or body. How hot your body is depends on how much fat you have, where it is, thyroid hormones, how much you sweat, how well you're adapted to the temperature, how much hair you have, whether you're a girl or a boy, how much muscle you have and whether you're special or not**"
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7k6k61 | What causes those pulled neck muscles that happen from doing nothing like yawning or rolling in your sleep? | Those pulled muscles that last for a few days but basically come out of nowhere: Is it a diet thing? Just a luck of the draw? | Biology | explainlikeimfive | {
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"Physiotherapist here! ELI5: It can be the position our neck is in at night or an injury from earlier in the day. Less ELI5: 1) Because many of our normal pain responses and reflexes are inhibited during sleep, we may find ourselves in a position of stress on the joints in the neck to which the stimulus to move does not exceed the necessary threshold for waking up. Sleeping on your stomach or with too many or too few pillows can cause this; try to have a pillow large/small enough that your head sits in 'neutral' or in the middle when you lay on your side. 2) More commonly, stress occurred on the neck the day before. Many people who experience whiplash from a motor vehicle accident will have a delayed pain/inflammatory response. This likely is due to the mechanics of the synovial joints in our spine. It may be a harmless move in the wrong direction or hours stressed in one position, but many people attribute this morning stiffness erroneously to 'sleeping wrong'. We call this an 'acute torticollis' - although generally this is a misnomer as many people won't actually have an altered head position. The neck is a complicated system of joints, muscles, and stability, so there's no one answer on how to avoid 'sleeping wrong', but one good exercise is strengthening the deep neck flexors longus colli & capitus, which pull the occiput (skull) into a bit of flexion (bent position) and provide tension and stability for the entire neck. URL_0 . Don't do this if you get pain during!",
"Most people get it from sleeping sitting up or sleeping in a bad neck position. If you're getting it just from yawning you might need to get your posture checked and some exercises. It's not a muscle it's a nerve pinch.",
"Another reason can be bruxism. The nightly grinding of the teeth can cause the the neck muscles to tense up. If it is strong enough it is visible on worn down teeth. Bruxism can be caused by e.g. stress or also by other rem sleep disorders."
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7k733c | how can a software update to Qi increase charging speeds? | Technology | explainlikeimfive | {
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"drc2ra3",
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"With modern batteries the charger isn't just apply power and it charges, it actually has circuits that control exactly how fast it charges so the battery isn't damaged (charging speed needs to be slowed down when they get near full). in your example Qi probably provides more power than the battery can use, and someone probably figured out that they actually can charge the battery faster than they thought without damaging it, so a software update can change the maximum charge rate to get it to charge faster.",
"A modern device's charging speed isn't limited by how much electricity can flow through the cable, it's limited by software to a safe rate of charging. Your phone tells the cable how much it can handle and the cable delivers. Because 'unsafe' in this instance can mean exploding Samsung phones they tend to program a lower charging rate than the theoretical maximum. As time passes they can test the devices more thoroughly and say \"this phone can handle a higher charging rate safely\". Then it's just a matter of updating the software on your phone to accept more electricity."
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7k7qqz | Midi sound illusion | For example, this meme song URL_0 its ONLY piano notes, no voice, however you can still hear his voice | Other | explainlikeimfive | {
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"drc5w99"
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"text": [
"The piano notes are approximating the sound of his voice and your brain fills in the rest based on memory. I do not know what the person in your clip is saying so I'm not hearing a voice."
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7k7udb | Are there any incidents of diseases jumping the species boundary from humans to animals? Was it bad? We know the reverse is pretty bad for humans. | Biology | explainlikeimfive | {
"a_id": [
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"text": [
"It's called reverse zooinosis. There is at least one case of a cat catching swine flu and dying from their human. Mumps and salmonella are two as well along with tuberculosis and MRSA."
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7k7ugd | (From my actual 5 year old) Can you take anti-venom before working with a poisonous snake in case you get bit? | Biology | explainlikeimfive | {
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"The side effects from taking anti-venom can be severe, including serum sickness, shortness of breath, and allergic reactions including anaphylaxis. Paraphrased from Wikipedia, they have sources. There's also the economic problem: Anti-venom is expensive. And then there's the logical problem: People will often have potential exposure to multiple types of venom, I.E. there are many different venomous snakes in Australia or the snake handler must handle many different types of snakes. Each situation could require different anti-venoms. I'm not a doctor, but given the potential side effects, mixing anti-venom probably isn't a solution."
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7k8mo2 | Why do ants and insects get trapped in pen circles? | [Example]( URL_0 ) [Another example]( URL_1 ) | Biology | explainlikeimfive | {
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"There are a few different explanations for this, depending on what the circle is made of. Ants will get trapped in chalk and baking soda circles, as well. A big contender is that ants travel largely by a scent trail left behind by other ants. If you watch ants coming for pieces of food left on the floor or the sidewalk, you'll see that they take the same route. A circle made of something like ink or sodium bicarbonate or chalk can disrupt this scent trail and cause almost a wall of sorts.",
"The ink has a solvent in it and the ant doesn't want to get solvent on itself. It's feelers detect it is getting close to the solvent, so it turns.",
"Ants are not smart. Not even close. Imagine they're like toy robots. They follow smells. The first workers to find food bring some back to the colony. They lay down a trail of smell. The next workers follow that smell trail and lay down their own. That's how mistakes like this happen. URL_0 A pen's ink is a mixture of chemicals. Some evaporate very quickly and also can dissolve other chemicals. If you were an ant, that line of pen would smell very strongly. Possibly strong enough to hide or break the smell of the correct trail. By the way, chalk can have a different effect. Diatomaceous powder can kill insects. Chalks are similar. And many 'ant' chalks from China have real insecticides in them. So with chalk, and especially ant chalks, the insects might be avoiding something really noxious.",
"Red inked pens and termites is a good example of the ink having a chemical in it that mimics termite follow pheramones. Its really cool to make termites do figure eights...not that i have ever done this.....noooooo (/s)"
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7k8twj | what is the difference between center of gravity and center of mass? | Mathematics | explainlikeimfive | {
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"The center of mass is the average center of all the mass of an object. The center of gravity is the center of all the forces of gravity of an object. The center of gravity only exists in the presence of a gravitational field. In outer space, objects will have a center of mass. But, the center of gravity will not mean anything. In a uniform gravitational field, the center of mass is the same as the center of gravity."
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7k95p6 | How does a monocle stay in your eye? | Other | explainlikeimfive | {
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"text": [
"It fits into your eye socket. Later ones had a metal ring called a gallery that went into the eye socket instead and held the monocle out a little bit so your eyelashes didn't hit it. This could be uncomfortable, so rich people had custom-fit ones made. A well-fitting monocle could be worn comfortably for long periods of time.",
"FYI: some people have much more deep eye sockets than others. Men typically have deeper sockets because they have a heavy brow ridge. So wearing a monocle is easier for certain people than others. It may seem impossible for most people because their eye sockets aren't deep enough."
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7k973z | why did Japan attack Pearl Harbor if America was minding its own business | Other | explainlikeimfive | {
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"The US wasn't really minding it's own business, and it inevitably was going to start minding its business less. It was supplying arms and finance to the enemy if Japan's allies, it was helping embargo fuel against Japan, and it was unlikely to go very long without entering. Japan actually was able to temporarily cripple the fleet (if they'd realized how badly and made a second pass they could have made it even worse). They just underestimated how quickly we could devote our resources to rebuilding.",
"America wasn't \"minding its own business\" as much as it was just not in open war with Japan. The biggest reason was an oil embargo, blocking the sale of oil to Japan. This was causing serious problems for the Japanese military forces."
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7k9qv2 | How to water powered flashlights work? | Last night at my company Christmas party a few of our technicians received a gift called a Hydra Light. Basically the concept behind it is you remove the “power cell” from where batteries would typically be on a normal flashlight. Dip it in some water, and put power cell back in and boom it turns on. How is this possible? Where/how is the power actually generated? | Technology | explainlikeimfive | {
"a_id": [
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"text": [
"It’s like a potato battery. The gadget contains pieces of dissimilar metal, perhaps zinc and copper. Water acts as the electrolyte. Eventually the metal will corrode away and the light will cease to function.",
"It's a [salt water battery]( URL_0 ), a type of [sodium-ion battery]( URL_1 ). I'm not sure I can explain the chemistry in detail in layman's terms (or at all - I only understand the basics), but in short, it works like a lithium-ion battery in that electricity is generated by positively-charged sodium or lithium ions moving from the negative terminal (anode) to the positive terminal (cathode) through a solvent called an electrolyte. In a salt water battery, the water acts as the electrolyte, and a source of ions from the dissolved salt. This type of battery appears to wear out quickly compared to lithium-ion batteries that are recharged by applying electrical current to move the ions back where they started instead of replacing chemicals with fresh ones."
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7k9u0r | Why after a good long cry can't we take a big deep breath without that huh-huh-huh tracheal contraction? | Biology | explainlikeimfive | {
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"Intense crying can cause less oxygen to enter the brain, therefore the contractions are like yawning, it’s supposed to allow more oxygen to enter. Source: I’ve cried once. And took an anatomy class once.",
"Those \"tracheal contractions\" are probably either diaphragmatic or ~~congressional~~ intraabdominal (thanks, Swype) muscle spasms, due to the strain that had been placed on them during the crying jag. You know how your legs get wobbly after doing a bunch of squats? Your breathing muscles get wobbly after being worked hard too.",
"I haven't done the \"internet research\" on this one but just based on observation it may be diaphragmatic in nature. The nature of those \"hiccups\" may be phrenic nerve overactivity through excessive crying. Oxygen levels/anxiety have too many inconsistencies to be wholly correct. For staters, a baby is more likely to just go blue if he/she has widespread hypoxia. Cerebral hypoxia may lead to a reduction in level of consciousness. Anxiety also seems inconsistent in that those\"hiccups\" may persist despite the subject ceasing crying. Other random observations that would support a diaphragmatic nature/spasms to the \"hiccups\" -Excessive crying is essentially prolonged periods of forced exhalations which naturally requires the diaphragm to contact for long periods of time - could explain spasms of a muscle after prolonged use -Methods to alleviate the \"post crying hiccups\" are oddly quite similar to alleviating \"normal\" hiccups: valsalva manoeuvre, etc... Source: doctor. Edit: Sorry for confusion. Diaphragm is indeed the primary muscle for inspiration.",
"Bit late, but wanted to share this. When we’re stressed or upset, we produce stress hormones and our breathing becomes fast. We’re often told to “take deep breaths” to relax us. That’s why it’s a fundamental part of relaxation activities like yoga and meditation, our rate of breathing has direct effects on the chemicals we produce which determine how we feel. When most of us are asked to take a deep breath, we inhale quickly, pushing our chests out and our shoulders up. But when we do that we only fill the top parts of our lungs. What we *should* be doing is taking in a long and deep breath, with the aim of filling our lungs with as much air as possible. The kind of breath you’d need if you were playing a wind instrument. Air right to the bottom of the lungs, shoulders stay where they are, tummy pushes out. When we do *this*, we’re stretching and controlling our diaphragm, a key muscle responsible for the rate at which we’re breathing. We’re making our body think everything’s fine, there’s no danger, and to be at ease. So our body responds accordingly, balancing out those chemicals and hormones. The huh-huh-huh after intense crying is our body doing this for itself. It’s stretching the diaphragm (which has been working overtime while you’ve been crying) and forces deep breaths. This has effects on the production and levels of cortisol, adrenaline and other chemicals and hormones we produce when things are scary or sad. It calms us down. Pro tip: hiccups are a spasm of the diaphragm. To get rid of hiccups, breath deeply (the method above) and hold for *as long as you possibly can*, then exhale sharply. While you’re holding your breath, really push the air to the bottom of your lungs. If you can even feel a hiccup while you’re holding your breath, then you don’t have enough air in there. Once you eventually exhale, the hiccups will be gone. It’s the hiccup equivalent of pulling your foot back when your calf cramps, and is the basis for the “receiving a fright” hiccup cure. Bonus tip: breathing in this way when you’re stressed will calm you down and make you feel normal again. But breathing is also linked with sleep hormones, so if you breathe in this way when you’re not stressed, and already feeling normal, you’ll soon find yourself yawning. Source: this all came from a university professor who gave talks on the effect of stress on the body and how to combat them, and has been invaluable to me for 15 years.",
"When we experience a state of ongoing trauma, the vagus nerve is generally involved in the freeze response. The dorsal vagus nerve has sympathetic functions inherited from the earliest vertebrates. The ventral vagus and its parasympathetic functions are more of a mammal inheritance, and mammals have complicated investment strategies resulting in weird adaptations. Crying is one such, and it is more or less piggy backing on systems that were never designed for it. In engineering terms, you are likely experiencing a failover mode.",
"Crying limits oxygen to brain. Oxygen takes a long time to enter through the alveoli (relative to CO2 diffusion). The longer the oxygen is in the lungs, the more diffusion takes place and the more oxygen gets in your blood. The huh-huh-huh causes the oxygen to stay in your lungs just a tad longer, so more oxygen can get in your blood.",
"It’s actually your diaphragm that’s contracting. Tracheal contractions would leave you gasping for air and be mildly terrifying.",
"Crying is probably an innate neurological mechanism to show to other people signs of being overwhelmed, whether it is by emotional or physical stress, or both. This is certainly a reflex behavior, given how babies cry at birth, and probably becomes more complex in what triggers crying as a person grows and forms complex regulation of their emotions. Crying later in life could facilitate social interactions to address the stressors causing a person (or people) to cry. Part of the nervous system that controls secretions (the parasympathetic nervous system) goes into overdrive; this is why you cry tears, have copious nasal secretions, and facial flushing. As for the breathing, my guess is the part of the nervous system that controls tidal respirations (breathe-in, breathe-out) get pushed strongly towards the breathe-out phase. In babies, this would produce a louder cry due to more air support. In children and adults, trying to breathe in for other reasons (to catch your breath, or to try and talk while crying - which we've all experienced at one memorable time or another) would be like trying to swim against the tide, with the body making your muscles of expiration push air out, but you are trying to push air in. This would explain the clumsiness of breathing during crying, and the \"tracheal contraction\" phenomenon. But, it is definitely not the trachea contracting, because the trachea is a fairly rigid tube like structure reinforced by cartilage and connective tissue. TL;DR: probably bad coordination between the muscles of breathing-in, controlled voluntarily, and the muscles of breathing out, controlled by a crying reflex. Source: I'm an Otolaryngologist-Head & Neck surgeon.",
"Aspiring SLP here with some ideas. The tracheal contractions you are talking about are that the vocal folds are not properly abducting (opening) during the inhale to allow for unobstructed breathing. This is likely because of the strong adduction that happens during crying. During the cry, you have a lot of muscular tension in your larynx and neck muscles. In addition, you usually expire past what is known as “Resting Expiratory Level” or REL (it’s the point where your exhale stops when you are breathing normally) which causes significant secondary muscle tension in addition to the tension already involved in the crying. This is also why the breath is so kind of spasmy. When you go past REL, your body does a recoil breath to return to normal lung volume levels. Try it: breath out until you can’t push any more air out and then let your body naturally relax and take in air. You’ll feel tension when you go past REL and you’ll feel the recoil breath to bring you back All of this put together leads to what we call Paradoxical Vocal Fold Movement. This means your vocal folds aren’t going where they need to for functionality (usually it happens when your vocal folds don’t open properly when you are trying to breath in). Paradoxical moments can happen to anyone and crying is an excellent example of one. Your vocal folds are staying adducted (closed) during the recoil breath which not only obstructs the airway so you hear the inspiration, but you are actually also vibrating your vocal folds on the inhale which is why you end up with sound. Fun fact, phonating on an inhale (singhaling) is actually really good for your vocal mechanism and is a great way to relieve muscle strain on your voice! Source: SLP graduate student with a strong background in voice"
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7ka5jw | Why does the inside of some dead tree branches appear jade green? | Biology | explainlikeimfive | {
"a_id": [
"drcrox7"
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"text": [
"Because they aren't dead. The guts of a tree can survive for quite a while after falling off the tree/losing it's leaves. In some cases decades - there are still 'extinct' trees pushing up green shoots from stumps decades after the blight wiped them out."
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7ka8nw | How is it that when you blow air out of your nose, you can still smell the scent you are trying to avoid by blowing air out of your nose? | Biology | explainlikeimfive | {
"a_id": [
"drcps5h"
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"text": [
"Because the same air is coming out of your lungs and back out of your nose. Like asking why you taste food when throwing up."
],
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7ka9l9 | What's the difference between Space Opera and Sci Fi? | Other | explainlikeimfive | {
"a_id": [
"drcr5ae"
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"text": [
"Science fiction is any work of fiction set in the future that deals with technology more advanced than our own. Space opera is a particular type of sci-fi that doesn't really care much about the specifics of the science and technology as much as it deals with grand narratives about galactic empires and grand heros. Star Wars is a great example of space opera. It has spaceships and robots and all that jazz but the story is really about good v. evil rather than the effects of that technology on society. You could tell the same story set in medieval/high fantasy world without really changing much. In contrast, look at something like *Ghost in the Shell* (just to pick a 2017 movie). The technology is central to the plot and you can't tell the story without it."
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7kaail | What makes some joints "crack" more than others? | I stretch my arms and hear crack sounds in my elbows. I asked my friends to extend his arms and do the same but there are no sounds. What makes my bones and joints so different from his? | Biology | explainlikeimfive | {
"a_id": [
"drcup7n"
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"text": [
"Basically, a joint cracking is just an air pocket being displaced within a joint. Joins with more potential for air displacement, ie fingers, back, neck, crack a lot."
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7kacqp | Why do consoles (PS4 etc) require you to download the game as well as having it on disc? It seems like a waste of drive space, and also seems to make it indifferent to just buying the digital copy. | Technology | explainlikeimfive | {
"a_id": [
"drcr5cq"
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"text": [
"As games get insanely complex, the rate in which a game can read data off a disk, even a blu-ray disk, is just too slow. Loading a huge level off the harddrive may take 10 seconds, where that same load with the speed off a blu-ray alone would take a minute... which becomes impractical. It was actually game designers who forced Sony (and Microsoft's) hands. (A blu-ray can read 27mb/s, a harddrive can read 300mb/s) (note: My numbers may not be perfect here, but it's in that ball-park)"
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7kaolz | How does vinegar breakdown mold/bacteria buildup | Basically, why is it a good cleaning agent? | Chemistry | explainlikeimfive | {
"a_id": [
"drd0pqc"
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"text": [
"Due to its pH of 2.0 and the acetic acid content, vinegar is an inhospitable environment for many microorganisms. Also, the high acidity level of it helps loosen mineral deposits, such as lime and rust, and dissolve soap scum due to their alkaline nature"
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7kb26s | Why do all these food companies have non gmo-labels on their products? Is it propaganda? | Other | explainlikeimfive | {
"a_id": [
"drcwmgq"
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"text": [
"If it's not a modified organism then they're not lying. I could poop in your salad and certify it as non gmo"
],
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7kbhqe | Why do carbonated drinks get/feel frothier when you swish them around in your mouth? | Chemistry | explainlikeimfive | {
"a_id": [
"drd0uuq"
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"text": [
"Carbonated drinks have a gas called carbon dioxide dissolved in them. They are bottled at high pressure so that the carbon dioxide is forced into the drink. When you first open the bottle, the pressure is relieve so a lot of the carbon dioxide leaves right away. There is still some left in the beverage though. Then as you drink it, carbon dioxide continues to leave. You can feel the bubbles. But all the gas doesn't leave at once. There is still some in there. If you swallow it, it often causes you to burp it out. If you swish it around in your mouth, the movement causes more bubbles to come out than before, resulting in a more frothy texture."
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7kbiv8 | Why do plant cells have chloroplasts and mitochondria, but animals cells seem to lack those? | Edit: Sorry, fully aware that mitochondria are present in animal cells, mistyped there. | Biology | explainlikeimfive | {
"a_id": [
"drd1f6q"
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"text": [
"Animal cells do have mitochondria. However, you are correct in that they don't have chloroplasts. Plant cells use chloroplasts to collect energy from light and transform it into chemical energy, but animal cells don't need this because animals don't get their energy from light. They get it from the food they eat."
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7kbxsx | how do two brown haired people create a blonde baby? | My baby came out super blonde, which was shocking as both my husband and I are brunettes, all our parents and siblings are brunettes, and our first kiddo is a brunette. The only non dark haired person in my descendants was a grandmother who had light brown hair. Yes, I'm the mom, and yes, my husband is the daddy. | Biology | explainlikeimfive | {
"a_id": [
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"Could be that you carry the gene, as does the father. Genes can be determined using Punnett squares, specific gene combinations are given letters, either capital or lowercase. Capital letters denote a dominant trait that will mask a recessive trait, marked with a lowercase letter. In this example I’ll say that hair colours brown and blonde are given the letter B. BB = brown hair Bb = brown hair but carries the blonde gene bb = blonde hair It’s likely that you and your husband both have Bb hair genes: Bb x Bb This is worked out in a grid format (usually better written down) x B b B BB Bb b Bb bb The letters of the parents genes are ‘crossed’ over each other, capital letters always go first because they are the dominant gene. So this means you’d produce: 25 % BB (brown hair only) 50 % Bb (brown hair carrying blonde gene) 25 % bb (blonde hair) = 75 % chance of brown haired kid, 25 % chance of blonde. The probability resets with each child, so it’s possible for you to have more blonde haired kids than brown if the blonde gene happens to strike. I’m sure other people can explain it better, I’m only using my year 12 biology knowledge but I tried, hope it helps!",
"In addition to the previous replies, some people are born with very blond hair that darkens over time. They have genes for darker hair but they have not switched on yet.",
"The genetics of hair color haven't fully been teased out yet, but it seems that the genes for blonde hair are recessive compared to the genes for brown hair. So if both genes are present, the person will have brown hair. Only when - by chance - a child only gets the blonde genes from its parents will the hair be blonde. What this could mean is that both you and your husband have recessive blonde genes that aren't apparent because you also have the dominant brown genes but your child, by pure randomness, only got those blonde hair genes.",
"Brown hair is dominant over blonde hair, so you need 1 brown gene for brown hair or 2 blonde genes for blonde hair. Everyone has 2 of each gene, but they can be different variations. So both you and your husband must have one brown hair gene and one blonde hair gene. The baby will inherit one gene randomly selected from each parent. So the baby needs 1 brown hair gene to get brown hair or 2 blonde hair genes to get blonde hair. The odds are 75% for brown hair and 25% for blond hair. You got lucky. We don't know how a lot of genes work but we understand this gene well."
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7kc59p | What makes the winter air smell so nice and fresh? | Whenever I open the window on a day with zero/negative C°, I'm hit with this unmistakable smell of winter. But there isn't anything to give off the smell, only cold air and snow. | Chemistry | explainlikeimfive | {
"a_id": [
"drd79d7",
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"text": [
"Maybe the \"clean air\" is just air without natural contaminants like pollen and animal pheromones. It could also be the physical feeling of your turbinate bones warming and humidifying the air entering your nose.",
"Not sure, here, but i have noticed that with negative °C there are alot less smelly things out and about. like: * Animals * flowers * Humans * fruits That also causes less contaminants like: * car fumes * Farts * Rotting stuff (like dead fruits or carcasses) But it could just be, that for you to smell something, you smell more, the less humidity you have. And in wintertime the humidity rises. Maybe it is the smell particles bonding with the water molecules or something along those lines."
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7kc7bz | What is that feeling you get in your legs when you witness something physically traumatic happen to another person? | Biology | explainlikeimfive | {
"a_id": [
"drd78yg"
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"text": [
"I'm far from an expert on this topic, but I would guess that it's related to your body's fight-or-flight response. When you see someone getting hurt, your body might respond by making sure that your legs are ready to run away or run in and deal with the situation."
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7kc9pf | How do printer cartridges work? | I've always wondered how the ink gets out of the cartridge and makes it onto paper with such detail. How does the printer create such fine details, such as small letters on an essay, onto paper so fast? And how do the colors mix to print out a photo? | Technology | explainlikeimfive | {
"a_id": [
"drda7kg"
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"text": [
"> I've always wondered how the ink gets out of the cartridge and makes it onto paper with such detail. I'm going to assume you are talking about an inkjet printer cartridge. That type of printer uses electrical charge to propel tiny droplets of ink out the nozzle and onto the paper. By carefully modulating the charge applied to a large number of tiny nozzles an image can be built up from the combination of those tiny droplets of ink."
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7kca9r | What causes small droplets of saliva to be launched out of your mouth sometimes when you open it. | Not sure how to properly describe it. Happens more often when you yawn I noticed but I have not the slightest clue how or why it happens. | Biology | explainlikeimfive | {
"a_id": [
"drd8p5c"
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"text": [
"I think you are refering to gleeking. In general, gleeking occurs when an accumulation of saliva in the submandibular gland is propelled out in a stream when the gland is compressed by the tongue. The stream of saliva is released in the general direction of the front of the mouth. If the mouth is open the jet may project several feet. Some people can do this on command by pushing/ramming their tongue against the the back part of their front upper teeth. I can lol lightly biting my tongue in different areas to stimulate salivation helps do it repeatly."
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7kcb0a | Why are some shapes such as triangles structurally stronger than others | Mathematics | explainlikeimfive | {
"a_id": [
"drd8j1z"
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"text": [
"Generally, certain shapes are strong because more things have to go wrong before they bend or distort. Think of triangles and squares. For a triangle to deform, a whole joint must completely fail. Mathematically, there is exactly 1 triangle with 3 defined sides. So a weakened joint won't let it move much. A square doesn't have that. You can deform a square in to a parallelogram without destroying the joints. They only need to bend a few degrees to really warp the shape. Additionally, once a square starts to collapse, it makes it energetically easier to keep bending it. This is why you often see cross-bracing (that X pattern) on square objects. It makes them much stronger without spending a lot of money. I-Beams are strong for a different reason. Their shape is physically hard to bend because the energy needed to bend goes up with cross-section located away from the center. So the part that gives it the most strength is the tips of the \"I\" not the center of the stem."
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7kclvw | Why are pregnant women not supposed to lie on their backs? What will happen if they do it anyway? Will it harm the baby if the pregnant lady rests on her stomach? | Biology | explainlikeimfive | {
"a_id": [
"drdai8v",
"drda137",
"drdzyd6"
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"text": [
"You have some pretty big veins/nerves that run up your spine. All the organ movement and general ‘build a kid’ stuff can put a lot of pressure on these and restrict blood flow and stuff. Also it’s pretty uncomfortable from what I’ve seen. Twice.",
"During the first trimester it is generally regarded as comfortable enough and safe. As the baby grows past that it puts additional pressure on your intestines and major blood vessels. Well not necessarily deemed as unsafe it is typically regarded as very uncomfortable. Sleeping on your stomach will also become uncomfortable as your bump grows.",
"The blood that goes to your lower body gets pumped back up to your heart through the inferior vena cava. The issue with being pregnant is that your uterus sits in front of it. Lying flat on your back late in pregnancy can cause compression and reduced blood flow to you and the baby. At 20 weeks, the baby is only ~1/10th of the weight it will be at birth so it probably isn't drastically uncomfortable yet. Later on, you may want to use (several) pillows to sleep angled to one side to take the pressure off."
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7kcm93 | What did cavemen do with their fingernails? | Other | explainlikeimfive | {
"a_id": [
"drd9zng",
"drd9yxm"
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"text": [
"They would have worn them down through rough use and wear on their hands, and by biting them.",
"Scratching, scraping, and picking the parasites out of their hair. Just like other primates."
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7kdby2 | Why does a li-ion/lipo battery explode when shorted out? | Explode is probably the worst case scenario; catch fire or even just puff up and smoke. Why do these rechargeable batteries react so violently when the old alkaline (disposable) batteries didn't? | Technology | explainlikeimfive | {
"a_id": [
"drdfgf3",
"drdgewh"
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"text": [
"The lithium atoms can crystallise and form a chain, that chain can short circuit the poles and it is this short circuit which can cause a fire. - URL_0",
"They have much higher energy density (meaning there is more energy stored in the same mass/size) than other batteries. All that energy has to go somewhere when a battery is shorted - it just turns into heat. Then the heat damages the mechanical structure of battery by burning off the layers of protective materials and exposes the chemicals inside which can now continue burning even after the electrical energy is exhausted. This is one of the reasons that electric vehicles will not get much better than they are now. The energy stored in batteries is very dangerous because it is easily released when shorted. Petrol, on the other hand, will not explode or burn unless mixed with oxygen. Lots and lots of oxygen. Therefore, it's much safer. We think of petrol as dangerous and batteries as safe but that's only because petrol energy density is much higher than batteries and we usually deal with much larger quantities of it. For batteries to be as effective in cars they need to have similar energy densities and similar size (actually, more size, because they can't use the oxygen from the air in the reaction) which pretty much turns them into bombs ready to explode and burn when shorted. And you can't just douse the flames because they don't need oxygen to keep going - all the usual firefighting techniques are less effective and you treat it as metal fire which requires specialist equipment to deal with."
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7kdi6u | Why does it get harder to fall asleep the more sleep-deprived you are? | Biology | explainlikeimfive | {
"a_id": [
"drdl79e"
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"text": [
"When you reach ~20 hours of no sleep, your body starts to produce little burts of norepinephrine (adrenaline making sauce) and dopamine (reward chemical / energy sauce) as a way to keep you alert since its evolutionary training is telling it you're either in danger or doing something strenuous to keep yourself out of danger. You may notice yourself getting kinda jumpy once you've been awake for 24+ consecutive hours since your adrenaline levels are getting significantly higher. The longer you stay up, the more adrenaline and dopamine you'll be producing (up to a limit that I'm not educated enough to know) which will eventually start to take it's toll on your body and mind. This is the \"strung out\" feeling people talk about when binging on stimulants (looking at you, college kids). When you get to this point, the baseline levels of adrenaline and dopamine in your body are much higher than they'd normally be. When you lay down to try to sleep, your mind is racing from the dopamine and your heart is racing from the adrenaline. Your body still thinks it's in danger mode, and it'll fight off sleep as much as it can. The longer you've been awake, the more in danger mode you'll feel. Eventually though, you will reach your physical limits and pass out, so there's that to look forward to. Edit: didn't read the full question, but I'd imagine that not getting enough sleep several nights in a row would trigger the same response as no sleep at all. I have no evidence to support this claim. Source: stress-induced insomniac in my highschool years, spent my sleepless hours Googling how insomnia works"
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7kdk3s | Why the hell do phones have to have a "minimum charge" before they turn on, can't they just draw power directly from the source? | Technology | explainlikeimfive | {
"a_id": [
"drdge9h",
"drdhk3p"
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"text": [
"Drawing power from the source would require extra circuitry that's not used 99.9% of the time. And the phone has literally no more space for it.",
"Laptops have more complex power supplies that allow them to run either from the battery or external power, and to switch automatically. Phones are smaller, and space within the phone is extremely valuable. So phone makers use simpler power supplies, which are smaller. The phone ONLY runs off the battery. Plugging the phone into external power ONLY recharges the battery. The phone will not start until the battery reaches a certain minimum level."
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7kdx5i | What causes water to "tornado" down the drain/sink/toilet? | Physics | explainlikeimfive | {
"a_id": [
"drdjnso"
],
"text": [
"Basically it's caused by the Laminar Flow. In fluid dynamics, laminar flow (or streamline flow) occurs when a fluid flows in parallel layers, with no disruption between the layers. At low velocities, the fluid tends to flow without lateral mixing, and adjacent layers slide past one another like playing cards. So, when gravity is pulling the water down, water molecules aligns in an uniform way. I have heard that earth rotation contributes to set the direction which way the water will spin. Imagine a river that reaches a cascade, it runs in a linear way until reaching the edge. In the sink the fall is not at the edge, it's in the middle, so the river forms in a \"linear spiral\" way."
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7kfkgn | How do polaroid pictures work? | How do the pictures just slowly come in there etc? | Technology | explainlikeimfive | {
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"text": [
"Freakin' magic, that's how! In a nutshell, a polaroid is a little envelope that contains all the chemicals needed to develop and fix the picture. Light hits chemicals that are sensitive to light, which react with reagents in a different layer that cause dyes to migrate into the first layer and become visible. Developing a photograph takes time (the chemical reactions aren't instantaneous), and the first process to do instant color prints didn't work very well. The solution was to add another layer of chemicals that opacify soon after the exposure to light. This makes it dark inside the layers, and allows the time necessary for the developing and fixing process to happen without being exposed to more light. That opacifier breaks down and becomes clear after a period of time. That's what you're actually seeing when the polaroid comes out grey and image slowly shows up.",
"Many of the other posters have covered the developing process well, but I would like to add one thing. The white section down at the bottom contains many of the chemicals in a little pouch. When the photo is taken and comes out of the camera, it passes through rollers which pop this pouch and press the chemicals along the picture. The chemicals are still contained within internal layers so they don't get everywhere, though.",
"/u/bazmonkey covered it well, but two things I will add: Polaroid photos only need time to develop. \"Shake it like a Polaroid picture\" was something of a nervous tick we developed as a society. Shaking it did not help the photo develop at all. Another thing; if you use something with a point to draw on the photo as it's developing (a screw driver, a nail, etc) you can get a pretty crazy effect.",
"It's already been covered pretty well, but for those who are wondering how its possible, it works basically the same way as regular film works, just in one package. Here is a very ELI5 version: 1. There are chemicals in the paper that are light sensitive, such as silver. Imagine it like a sun burn, you can place a stencil on your body, then expose it to light and you will have a darker skin color inside the stencil. When silver is exposed to light it gets darker, this is why we have a negative when we take a film photo. The brighter the light, the darker the silver becomes, so its giving the opposite effect of what we see with our eyes, so it needs to be reversed into a positive. 2. Even in polaroids, the exposed image starts as a negative, but the chemicals in the developer bleach out the negative and you are left with a positive. 3. The white tab you see at the bottom contains the developer, when the polaroid is ejected, the developer is squeezed out over the exposed image, which stops anymore exposure and also starts to develop the image. After the image is developed and stopped, the negative gets bleached out after it leaves its imprint as a positive. BONUS: When dealing with chemicals, temperature has an effect on developing times and the effect of the development. If you have the chance, put your polaroid/instax in the freezer and then go outside and take a picture. Then leave it out in the sun and take the same picture. There will be a noticeable difference, such as different color-casts or exposures.",
"Here is how the old 600 film used to work, [Each instant photo contained chemical pouches at one end]( URL_0 ) I remember as a kid when the photo was taken my grandfather would put them face down in a small cardboard box that he carried the camera in to help keep them away from light as they developed. Also wiki has a great right up about the [instant film]( URL_1 )",
"Anyone here know how the new Polaroids hold up against the impossible ones?",
"Not a photographer or an engineer but I read about the process a few years ago. There are two chemical pouches on the photo “slide”. One is a mixture of the standard chemicals used to develop photos. The other is a chemical that is opaque and acts as its own dark room. The latter is design to protect the former obviously but it’s only good for a certain amount of time. Once it’s taken all the light it can, it starts to fade but by this time, the developing process is done and your photo become visible as the darkroom fades.",
"Each photo is a little package that has a silver coated pice of film, and a bunch of other chemicals that react with the silver and the film. One of them is an acid, one of them \"fixes\" the image (it makes it not smearable), chemistry stuff. When the picture is taken the negative (the film) is exposed to light coming through the lens and it makes an \"imprint\" in the silver coating on the negative. Then rollers squish the other chemicals onto the negative, completing what a photographer would do in a darkroom right there in the park. You'll note the opaque black back on polaroid pictures and the peel off backing. So then you wait a few minutes for the exposure (chemical stuff) to happen then peel away the excess chemicals and voila, you have a photo of your dog! You can under expose, (its all white!) or over expose (black box) your pictures if you peel them too early or too late."
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7kg1zb | Why can't we use diesel in a petrol engine and vice versa? For that matter, why can't we use any combustible fuel in any internal combustion engine? | Chemistry | explainlikeimfive | {
"a_id": [
"dre222m",
"dre0bfd"
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"Because the manner of combustion changes depending on the engine. Spark-ignited engines need fuel that resists autoignition at high compression ratios, and only burns when ignited by the spark plug. This resistance to autoignition ends up being measured by the octane number. Compression-ignited engines (so, diesels) are the opposite; they *require* a fuel that will reliably autoignite. This proclivity to autoignite is measured by the cetane number, which is essentially the opposite of the octane number. As a result, diesel engines need fuels with high cetane numbers, while gasoline engines need fuels with high octane numbers, but because you can't really have a fuel that scores highly in both categories, fuels end up only being used in one type of engine or the other. *That being said*, you can use all sorts of liquid combustible fuels in each type of engine. For example, jet fuel, kerosene, and even petroleum-based rocket propellants (e.g. RP-1, which was used in the first stage of the Saturn V rocket) go up fine in a diesel engine assuming you retune the ECU a bit, as they're all just variations of kerosene, as is the ULSD you get at the pump. Similarly, ethanol and methanol burn pretty similarly to gasoline, and so can often be used in gasoline engines with no changes other than a possible retune. In addition, if you're willing to work at it, you can make each type of engine run on other exotic hydrocarbon fuels like CNG, LNG, dimethyl ether, hydrogen, syngas, pure methane, heptane, or things like that.",
"Yer not alone in askin', and kind strangers have explained: 1. [ELI5 Why can't gasoline/petrol engines work with diesel, and vice versa? ]( URL_0 ) ^(_5 comments_) 1. [ELI5: What makes gasoline and diesel fuels incompatible? ]( URL_2 ) ^(_9 comments_) 1. [ELI5: The difference between gas and diesel, and why certain cars use one and not the other ]( URL_4 ) ^(_94 comments_) 1. [ELI5: What is the difference between petrol and diesel? ]( URL_8 ) ^(_13 comments_) 1. [ELI5: The difference between Petrol and Diesel and the Petrol Engine and Diesel Engine? ]( URL_3 ) ^(_4 comments_) 1. [ELI5:Why can you not put diesel fuel in a gasoline burning engine? ]( URL_1 ) ^(_19 comments_) 1. [ELI5: Diesel vs Unleaded; How both engines work and why the fuels are so different and toxic to the opposite engine? ]( URL_6 ) ^(_6 comments_) 1. [ELI5: Why does diesel in a petrol engine do so much damage? ]( URL_5 ) ^(_25 comments_) 1. [ELI5: why can`t petrol and diesel engines use the opposite fuel? What happens when the wrong type of fuel is filled? ]( URL_7 ) ^(_5 comments_)"
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7kg3zf | Why did Video Games only work on Channel 3? | Technology | explainlikeimfive | {
"a_id": [
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"dre4w4t"
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"The video game system (and other external devices like a vcr) connected to the TV through the coaxial cable jack. At the time it was common for the TV to not have other inputs like A/V etc. So, the connector would make the signal come out in a way to be tuned on the TV, matching the same signal it would be looking for in channel 3. This process. is known as modulation.",
"**tl;dr:** TV's didn't have 'inputs' on them for the first 30 or so years they existed so they only way to get a signal in from an external source was to hack the antenna to replace content of a particular channel and make sure the TV was tuned to that channel. Make it a low channel number for backward compatibility, allow two channels for technical reasons. The rest of this post is a rough outline of the development of television inputs. Might be an interesting read if you want to know how TV was in the early 80s. Back in the day, televisions received video only over the air so you had to connect an antenna. There were no VCR's or DVD players or even cable boxes. You had ~13 channels to select from using a physical dial on the front of the TV. So, back in the day, someone devised a way where you could connect a device to the antenna connectors on the TV and watch premium channels. This was cable. The box acted like a pass-through and you'd connect your tv antenna to the back of the cable box instead. There's also be a CATV cable connected to the back of the cable box containing the cable signal from the provider. Cable offered a lot more channels than what your 13 position dial on the TV did so what they did is make it so you had to tune your tv to a particular channel to see the cable tv. What the cable box was doing was basically replacing whatever was coming in on the antenna for this particular channel with whatever cable content you were trying to watch. At some point, cable companies eventually standardized on channels 2 and 3 (using a switch on the cable box) because it's easier to send a clear signal on a channel which isn't used in your area than one that is. Also, due to technical issues, you generally wouldn't have content on BOTH channels 2 and 3 in any given area. Also, low channel numbers pretty much guarantee that old TV's from the 60's which only had something like 5 channels would still be able to connect to cable. (In the 80s, it wasn't uncommon to be using a black and white television from the 60s. Shit was built to last.) So JVC and Sony come out with video cassette systems. This is all fine and dandy, but how do you connect it to a tv which has only power and antenna connections? The same way as cable. There's a signal in connection which connects to your antenna or the signal out from a cable box. There's a signal out which goes to the TV's antenna connection. Now, it this point, I should mention something about TV signals. Basically, each tv channel is a few sound signals and an NTSC signal (or PAL if you live in some backwater European country) then the whole thing is modulated with an FM carrier signal. If you keep the FM carrier frequencies separated by a few megaherts, you can send multiple channels (multiple video and audio streams) through a single wire. VCR's and (less so cable boxes originally) needed to only send one signal. All this channel 2/3 bs was because the only way to get a video signal into the TV was to modulate the whole signal with an FM carrier just so the TV can demodulate it. Way complicated for just trying to get one channel into a tv. RCA started building TV's where you could send it an unmodulated NTSC video stream. This is literally the video stream the comes in over the air, but with the FM modulation... demodulated... and the sound stripped out (they used a couple additional connectors for sound). Just about every modern tv up until a few years ago had this: three RCA connectors colored red, white, and yellow. Most VCR's, all game systems, and most cable boxes and pretty much anything else that sent a signal to the TV could use the RCA system. Since you got a better picture than using the antenna connector, it was always recommended to use this if possible. To maintain backward compatibility, though, these devices would still contain all the electronics to modulate the signal and replace channel 2 or 3 on whatever input signal was coming in. Now... on game systems like the NES, you had an external device, the RF Switch, which had a signal in (from cable/antenna) and a signal out (to tv). There was also a connector which ran to the NES. When you turned on the NES, it would send the broadcast signal on either channel 2 or 3 to the RF switch. The RF switch would then inject the NES's signal into the TV's antenna. And now you're playing SMB3 or the Legend of Zelda, or whatever."
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7kg5d4 | Socrates arguments for the immortality of the soul and the cycle of opposites argument | Other | explainlikeimfive | {
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"The ELI5 is that we assume that the soul is the opposite of the body, and since the body is mortal, the soul is not mortal. As for why he would just assume that the soul is the opposite of the body, I think the relative looseness of his reasoning probably had something to do with his plans for the following day."
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7kg9zw | Does the cliche "Don't talk, save your strength" have any actual merit to it? | Biology | explainlikeimfive | {
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"text": [
"Talking demands particular breathing patterns. Physical exertion requires different ones. If you talk while trying to engage in physical activity you won't take in enough oxygen and you won't be able to do the activity as well. Furthermore, humans are terrible at multitasking. Talking distracts you from whatever else you're doing so you won't do it as well.",
"I've always assumed it was on the same vein as not wanting to move someone after they've been injured. It doesn't seem like the act of talking would do much, but it creates movement and that can cause current problems to get worse. Couple that with the fact that a good deal of people are pretty animated while just talking, and the real possibility that things will be hazy for the victim after suffering trauma, it's easier to tell people to shut up. & nbsp; I don't know how correct it is, but that was my conclusion, and it sounds convincing enough to be true."
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7kgdba | Cows and the carbon cycle | **note:** I flaired this biology, but I could see this being chemistry or physics. Let me know if there's a better flair category. I frequently hear that meat production, and cows in particular, produce CO2 emissions. Both methane, but also regular CO2. I haven't quite understood the mechanisms. This is more a case of confusion than doubt on my part, and I'm looking to figure it out. I know that generally, the carbon emitted by living organisms during the year is taken up by plants, and everything balances out. I'm not talling about fossil fuels, I just mean animals breathing out CO2. I can think of three ways cows produce CO2: 1. Breathing 2. Clearing land to feed cows. If forests are cleared, this puts lore carbon into the atmosphere. 3. Methane farts. Is this more carbon per se, or is this merely front loading it? (Since methane produces faster warming than Co2) 4. Some other factor I'm ignoring? Cows produce CO2 by breathing. But, so do humans, and dogs. So, which of the following is true? * Cows produce worse CO2 than humans. A new cow is destructive, a new human isn't. * Both are destructive. Every new animals hurts the carbon balance somewhat. * Cow and human breathing aren't destructive. A new animal's CO2 breath is balanced out by plants. Next, land use. Clearly, if you burn a forest and raise cows on it, you have released the carbon from the forest. But, that happens with soy or wheat too. So is it? * cow farming does something qualitatively worse than grain farming, or * cow farming isn't per se worse, but it's a less energy efficient way to produce food for humans and so more total farmland is required or, * something else I'm ingnoring? The methane, I have no clue about, so that's a truer ELI5. And, if I'm missing anything, let me know. These questions prompted by eating at a brazilian barbecue. | Biology | explainlikeimfive | {
"a_id": [
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"text": [
"You're overthinking it. [Here]( URL_0 ) is a scientific article about it, but it's still kind of complicated. The easiest way to think about this is the 10:1 rule. For every one pound of meat you, need *ten pounds* of feed for it. This means that if you ate the feed directly (eg, corn), you would use only 1/10 of the amount of resources. Between feed, storage, transportation, etc, animals are just more \"expensive\" in terms of carbon, methane, etc. than pure vegetables are. This doesn't mean you should be a vegan, but it's a compelling argument for shifting how we, as a society, structure our food consumption."
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7kgfvy | How does glue not stick to the inside of the bottle? | Chemistry | explainlikeimfive | {
"a_id": [
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"text": [
"Lack of air. Glue will dry when it is exposed to air. If there isn't air circulating in the bottle, it won't dry. Leave the bottle open, and you will get dry glue.",
"There are different kinds of glue that work differently. Some glues have water in them. If that water evaporates the leftover can stick sth together. In other kinds of glue for example superglue is no water. But it needs water from the air for it to stick materials together. I have found a great eli5 on the internet: URL_0"
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7kgmug | How do waterless toilets work? How do they not smell constantly? | Technology | explainlikeimfive | {
"a_id": [
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"text": [
"They use a puck that reduces the smell when urine passes through it. Then the urine/cleaner combo go into the drain. The drain still uses a p-trap or a U-shaped bit of pipe that will hold liquid to prevent sewer gases from escaping.",
"The two main types of \"waterless\" toilets are composting toilets and electric incinerator type toilets. Incinerator type obviously need electricity and simply burn up the waste with odor handled by fans and venting. Composting type units store the waste in sealed containers and use similar types of venting. Then there are the vault outhouses in most forest service campgrounds which do smell constantly."
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7kh2t4 | Animators of Reddit, when producing an animated film, do the voice actors read all their lines first and the animation is made to match the actors' lines, or is the film animated first with the voices second to match the animation? | Other | explainlikeimfive | {
"a_id": [
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"text": [
"The voice actors read all their lines first. Many scripts for animated films are recorded and then never made into full movies. Other times, they'll record the script with one actor and then replace a character's voice with another voice actor before starting the animation of the movie. The actors get paid a lot of money, but that cost is still nowhere near the cost of doing all the animation. The animation is also very time consuming, while the voice acting can completed very quickly."
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7kh4t0 | What is 'Optimistic Nihilism'? | Other | explainlikeimfive | {
"a_id": [
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"text": [
"Basically and without boring details? Accepting that your life and existence has no defined meaning/purpose at all. And at the same time accepting that this absence of meaning/purpose is for you to fill up with your own decisions, things that you believe in and want to be. May it be a dream, or a hope. The Universe is gonna fade into darkness someday according to the laws of thermodynamics, but why would you bother if you'll be long dead before it? Go outside and watch all the stars, you were born in a time they had never burned so bright. Accept all the painful truths Science can give to you, and make use of it not to \"Get sad because life is meaningless\", but instead feel happiness for knowing you're free from Dogmas.",
"Want a truly ELI5 answer? The universe is like Minecraft. It has no real purpose or goal, which invites you to create your own and have fun doing that.",
"Life is pointless. & nbsp; No matter how many juice boxes you trade for fruit rolls, or epic wooden block castles you smash with tonka trucks.. Nothing really matters. & nbsp; Tho despite the bleak, dark, nothingness that is the truth of reality & our existence within it.. You should still try to live a good, honest, decent life. & nbsp; While your life may ultimately have no true or predestined purpose.. and definitely won't even register as a blip on the immeasurably long timeline of the universe.. You can still build a fulfilling life worth living. & nbsp; & nbsp; So yeah.. not sure how accurate that is, but as an ON myself.. That's would it means to me. Cheers!"
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7ki4fo | If cinemas now get movies as a Digital Copy how come they dont get copied and leaked online well before the DVD release date? | Technology | explainlikeimfive | {
"a_id": [
"drejgoy"
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"text": [
"There are small watermarks in each copy that uniquely identifies it. If a theater were discovered to have leaked their copy, the movie studio would stop doing business with them, which would almost certainly cause the theater to go out of business. So theaters are *heavily* incentivized to be as protective as possible of the copies of movies that they have received."
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7ki9nn | How human bodies will not recognize or ignore pain during physical altercations and injuries. | Biology | explainlikeimfive | {
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"text": [
"Your nervous system floods your body with chemicals that amp you up to fight, which in turn also releases endorphins that block pain so that you can continue to fight and possibly live in a life or death situation. It’s survival."
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7kia4c | Why are the simple sugars in fruit considered to be better for you than those found in candy? | Biology | explainlikeimfive | {
"a_id": [
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"text": [
"One reason is that fruit contains fiber, to slow down the digestion of the sugar. Eating an orange is better for your body than drinking a glass of orange juice.",
"They are only considered \"better\" by people who do not grasp simple scientific concepts. The reality is, all sugar has an equally negative effect on the body, but naturally occurring sugars happen to be found in less quantity in fruits and vegetables that tend to have much higher nutritional value in general than candy (which is a concentration of sugar and typically with little to no value to it).",
"It's not that the sugar is better, it's that there's less sugar per gram of fruit than you'll find per gram of candy. In a 100g orange (medium-size-ish) there are about 10g of sugars. In a 100g Mars bar, there are about 68. You'd have to eat 7 oranges to get that much sugar! And you're not going to do that in one sitting. So fruits tend to be more self-limiting."
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7kibb1 | How come when you have a fever and your temperature is so high you feel cold? | Biology | explainlikeimfive | {
"a_id": [
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"text": [
"Because the way a fever works is by tricking your brain into thinking that your normal temperature is *supposed* to be higher. So, instead of 98.6 degrees, your brain might now register 104 degrees as its desired normal temperature. So suddenly your core body temperature is 5 degrees lower than it \"should\" be, so you feel the same as if you didn't have a fever, and your core temperature had dropped to 93 degrees. Further, even once you get your core body temperature up to the brain's desired fever range, the air around you is a lot colder compared to your temperature than normal. For instance, if you're running a fever of 104, and you're in a room that's 72 degrees, it feels the same as not having a fever and being in a room that's 67 degrees.",
"Agree with what poster above said but I would like to add that one of the ways your body raises your core temperature is by constricting blood vessels in your skin and extremities so that warm blood moves into your core. This causes your skin temperature to drop and the symptoms known as \"pale, cool, & clammy\". Furthermore the temperature detecting nerves that you are aware of are all on your skin which is now rapidly cooling due to lessened blood supply. Therefore you feel cold."
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7kigo3 | How does a progressive web app(PWA) work? | I'm interested in the topic but I find it hard to understand some points of it. From research, I know that a PWA acts just like a native app but instead, it's on a website. So how does it actually work? What are the best uses of PWAs? | Technology | explainlikeimfive | {
"a_id": [
"drevqls"
],
"text": [
"From my understanding: It’s an application hosted on a web browser. Let’s say you open an application, like any other, it feels and looks like one. But on the back end it really opened up a web browser to host the software on. This way, the software is always up to date, bugs can be repaired quickly, etc."
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7kigyh | Why is sweat colourless and not yellow like urine? | Chemistry | explainlikeimfive | {
"a_id": [
"dremjf6",
"dremg74"
],
"text": [
"Urine's yellow color is attributed to an organic molecule called Urubilin whereas sweat does not contain this molecule.",
"> Why is sweat colourless and not yellow like urine? Because sweat doesn't contain urea which is yellow. There isn't any reason why sweat would contain waste products like urine does because sweat isn't produced in order to purge such things."
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7kihr0 | How was mail delivered in the 18th century if there weren't exact addresses? | Technology | explainlikeimfive | {
"a_id": [
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"drenj3s",
"drenjtm"
],
"text": [
"It would go to the local pub or other establishment that people went to often. Then people would just pick it up as they happened in.",
"It was a real mess is the best answer. Really, mail would just go from post-office to post-office and it would be up to individuals to come down and collect their mail. IF a post-office was not nearby, then the mail may go to a \"by the way\" (A business that was by the way of that person). A good article on this with a few snippets from it: URL_0 In practice, the post offices of these days did not generally deliver mail to households or businesses directly, but only from post office to post office. A 1796 report to the House gives some flavor of what a dog’s breakfast this system could be: “ALL THE PAPERS AND PACKAGES DELIVERED TO DISTANT CUSTOMERS AND TO BE LEFT AT DIFFERENT OFFICES AND PLACES, ARE PUT LOOSE INTO THE PORTMANTEAU WITH OTHERS, FOR SUBSCRIBERS LESS DISTANT, AND AS OFTEN AS THE MAIL IS OPENED THE NEWSPAPERS ARE THROWN TOGETHER OUT OF THE PORTMANTEAU IN ORDER TO FIND THE INDIVIDUAL PAPER AND PACKAGE TO BE LEFT AT SUCH OFFICE OR PLACE. AT SUCH TIMES THERE IS GOOD REASON TO SUPPOSE PAPERS AND SMALL PACKAGES ARE TAKEN AWAY BY PERSONS PRESENT AT THE OPENING OF THE PORTMANTEAU, TO WHOM THEY ARE NOT DIRECTED, BUT WITHOUT THE KNOWLEDGE OR PRIVITY OF THE POSTMASTERS OR CARRIERS OF THE MAIL.” On top of this, people could pay additional money to a business or an individual to hand deliver letters to you.",
"\"Mail\" - that is, a government postal service as we know it, with stamps and mail carriers who delivered mail to your home - did not exist until the 19th century. In the 18th century, you wrote a note and sent a servant or courier to take it across town, or you sent it along with a coachman to the nearest village where the recipient was. And generally it was the recipient who had to pay the delivery fee. Or you sent it along with a friend."
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7kil2p | How do cinemagraphs work? | I recently stumbled across r/cinemagraphs and can't stop watching those things, they're beautiful! But I can't wrap my head around how they work. [This]( URL_0 ) one over here for example is only one(!) second long but I still can't see a cut in there. How come this looks like it's moving forever? I tried googling it but only got some photoshop tutorials on how to make those things and since I have absolutely no clue how to use photoshop I didn't understand much. I also searched this subreddit and someone asked 2 years ago already but didn't get any answers. | Technology | explainlikeimfive | {
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"They are .gifs someone takes a video or a segment of a video and they cut and play with it until it's seamless. The start of the .gif has to match the end as best the editor can perceive.",
"You start out by picking a piece of video that can be looped. There are several ways of going about this. The easiest way is to find a piece of footage that actually loops. For instance, a bicycle wheel spinning. The second way is finding a piece of footage that has a repetitious movement that doesn't exactly loop but is complex enough to hide the repetition in its complexity. Finally, you can make a rough loop and then go in to edit each and every frame of video by hand until it loops. This is more manageable than it sounds since these types of images usually are really short. Since most of these cinemagraphs take scenes out of movies, the last part is picking only one part out of a scene to loop. In your river example for instance, the people standing there would probably be moving. Even if they're not really doing anything, people don't stand perfectly still. So you take one frame you like, mask out the parts you want to be static and non-moving and use those as a mask on top of your repeating animation. Incidentally, it's a lot easier to do this in Adobe AfterEffects (video special effects software) than it is to do in photoshop. Although you might end up using both."
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7kil4o | Why can't wild animals who have been injured and rehabilitated by wildlife be released back to the wild instead of kept in zoos, aquariums, or sanctuaries? | You know how when you go to the zoo or aquarium some animals have a sign that explains how they were "rehabilitated?" Why can't these animals be released back into the wild. I get that animals bred and born in captivity probably wouldn't survive in the wild, but what about those that were taken from the wild to be helped? Why can't they just be treated/helped and released back into the wild? Is there a reason why these zoos and aquariums keep these animals and want to advertise so clearly that they are responsible for the animal's "rehabilitation?" | Biology | explainlikeimfive | {
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"Many ARE rehabilitated and released. Some individual animals are not suitable for release, though, either from lingering injuries, or perhaps from behavior issues like associating humans with food. A grizzly bear cub that thinks humans are all cafeteria lunch ladies isn't going to be safe to release into the wild. A zoo also has a vested interest to keep animals for research purposes, education, and as attractions.",
"It depends on two major factors, among others: the species, and the nature of the injury. Some animals don’t “unlearn” much in captivity, and when released know exactly how to survive. Others adapt to captivity more deeply and quickly, and “forget” how to be wild again. Many of the animals like this in zoos were critically injured, like an eagle with a bad wing. It can chill in an enclosure and eat and live out its days, but, despite being healed, will never fly well enough to hunt in the wild again.",
"Sometimes they can.. and sometimes they are but sometimes it's not possible. Sometimes the animal has on-going medical needs and it wouldn't live in the wild. Sometimes the animal was hurt and has a permanent disability that makes it difficult for that animal to find food or to avoid predators. Sometimes the animal got use to people and releasing it might mean that it's too friendly and would be a problem. Sometimes if the animal was from a herd or pack.. we don't know what would happen to that animal if released back into the wild in a different herd/pack (or pod of dolphins).. would it be accepted or beaten up? So really it depends on the species and the animal itself. Ideally the would want to release the animals unless they are rare and endangered and will help us to learn about that species as a whole or for breeding."
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7kiph6 | Why do amphetamines suppress appetite? | So it’s pretty well known that a lot of stimulants/adhd meds also make it a lot easier to lose weight. Why? It seems like you would burn more calories/be hungrier on something like that. | Biology | explainlikeimfive | {
"a_id": [
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"These type of drugs are what's called sympathetic nervous system agonist, which means they make your fight or flight system work overtime. Your appetite is linked to your parasympathetic nervous system, which is not being active when your sympathetic nervous system is in play.",
"Dopamine is one of the nuerotransmitters that signals satiety. When the brain is flooded with dopamine, it will think you are already full. Amphetamines will also increases other nuerotransmitters like epinephrine and norepinephrine which activate the sympathetic nervous system and keep you from being bothered by things like hunger (if you need to run from a predator or something equally stressful, you don't need to stop and eat.)"
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7kirn8 | Are there climate equivelents in the southern hemisphere to northern hemisphere locations? | Other | explainlikeimfive | {
"a_id": [
"dreq4hn"
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"text": [
"Part of the problem here is you don't have much to choose from. There is a lot less land in the southern hemisphere, especially at mid to high latitudes. San Franciso is about 37^o N. The 37^o S latitude line is further south than all of Africa, and most of South America and Australia. Melbourne is the only large city in the southern hemisphere at an equivalent latitude, with Cape Town a bit farther north. Both cities are a bit warmer than San Francisco, especially in summer"
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7kis8o | How do music synthesizers work? | Technology | explainlikeimfive | {
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"text": [
"A synth has a number of different voices or oscillators (sound tone generators), each of which can produce waves of different shapes (sine wave, square wave, saw tooth, triangular wave, and so on). It can combine the waves to make complex sounds, and it can vary the way the sounds attack, decay, sustain, and release to make the sounds mimic existing instruments like pianos. URL_0"
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7kix9n | How do we pasteurize eggs without cooking them? | Chemistry | explainlikeimfive | {
"a_id": [
"drer26z"
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"text": [
"The nasty things that live in eggs mostly die around 140 degrees. Yolks start to set at around 160 degrees. By carefully heating the egg so the center reaches 140 and then cooling it before any part reaches 160, we get a fully functional egg without any live nasties."
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7kj59g | -How post-puberty human males have the ability to sing such low notes despite the average vocal cords being so short. | Consider how thick and long the bass register strings are on a piano, and compare that to the average set of vocal cords. Granted the vocal cords can relax tension a lot more, but how is the volume maintained (think of a professional basso opera singer)? Maybe this video will help? [ URL_0 ]( URL_0 ) | Other | explainlikeimfive | {
"a_id": [
"drev7ch"
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"The term \"vocal chords\" is a misnomer. They're more often and accurately called the \"vocal folds.\" The organ itself is called the *glottis.* Our vocal folds are not a string instrument. The folds are a pair of muscles that form a valve that is normally shut. When you push air behind the folds, pressure builds up until the folds open and a pulse of air comes out. The folds then slam shut, due to tension that you apply by tensing the muscles. Then pressure builds again, and they slam shut. This creates a train of pulse waves. The time in between each pulse is the period of the waveform, which is the reciprocal of the frequency. The amount of tension and the physical size of the folds impacts what pitch is created. Men tend to have larger and looser folds, allowing for deeper pitches. Some crazy stuff can happen then the folds are damaged or mucus builds up. For example one of the folds can get stuck, the result is that the period of the waveform is doubled and the pitch is dropped by an octave."
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7kjtt5 | Why does food sometimes pop in the microwave as if it was very hot, but still come out cold? | Other | explainlikeimfive | {
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"It's just the water evaporating because of the microwaves. It works by heating the water inside the food.",
"Microwave ovens, especially older/cheaper ones, heat food rather unevenly. The ends or liquid parts of the item heat more quickly, and even then small regions of those parts can heat up faster than others. The microwave has hot spots, physical regions inside that get more microwaves than other parts. The popping is because some little part of the food was actually getting very hot and boiling. But even though that part is super hot, other parts of the food haven't absorbed much heat, haven't gotten many microwaves zapping it, and could still be frozen. When you set your microwave to less than high power, it doesn't actually make weaker heat. Rather, it just turns the microwave on and off every 10-15 seconds during the time. The point is just to cook it a little more slowly, to allow the heat to spread more evenly through the food. This is also why instructions tell you to leave the food in the microwave for a couple minutes afterwards. Also just giving time for the heat to spread more."
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7kjzok | Why are some allergies much more common than others? | For example why do a lot of people have peanut allergy? | Biology | explainlikeimfive | {
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"drg4rja"
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"text": [
"Peanut allergy isn't actually that common of a allergy compared to others, its just that generally the reaction is very severe and on a hair trigger. So they are more vocal about it. They can't just keep it to themselves cause if they get a reaction, It requires their epi pen and a hospital visit. Someone allergic to cats visiting a cat owner can generally just pop a pill, or toughen it out for a few hours without ever informing the owner.",
"No one seems so have actually answered your question. **We don't know why some allergies are more common than others.** We know how allergies work, we know basic stats on prevalence, but we don't know why say for example more people are allergic to shellfish than strawberries. IIRC, We also don't know why some allergens elicit stronger or more deadly reactions (e.g. shellfish & peanuts vs. strawberries)."
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7kjzpy | Labor theory of value | Is there truth in 'Labor theory of value'? Explain please. pros and cons if you can :) | Economics | explainlikeimfive | {
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"text": [
"It’s a Marxist concept that all value in a product comes from the labor used to produce that product. And therefore, the difference between the price of the product and the wages paid to the workers that produced it represents the profit to the capitalist, which Marxists saw as illegitimate. It’s not correct, because a product’s price actually reflects several things other than labor - resources, technologies, know-how, and capital being invested in that product instead of other things. Even people who think some of Marx’s ideas have value admit that he was wrong about this.",
"Is it homework time again? If a tree grows in the forest it is there. If you cut it down, drag it to the road, cut it up into fire logs, load it, and take it to the city to sell as firewood you expect to sell the tree for more than it was worth standing in the forest. You did work to produce the fireplace logs. You increased the value of the wood by your work. Now the best firewood is aged and dry. Stack your firewood under a shed, let it dry for a year. Sell it for more. Sell the log to a saw mill. They make lumber and sell it for more than the price of the fire wood or the log. They sell the bark trimmings for fire wood but it sells for less than fire wood. Everyone is happy."
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7kk3zy | - When does a body determine its dominant side? How does it do this and can it be changed with outside influences? | Biology | explainlikeimfive | {
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"I've been lead to believe our eyes play a part in this from my optometrist. I'm left eye dominant which means I *should* be left handed. But since my grandmother \"encouraged\" me by smacking my left hand anytime I tried to use it to not be lefty I am right handed. To be fair my grandmother is very old and where she grew up left handedness is a sign of the devil so that's what prompted her to change me. Superstition.",
"We’re not sure how/why handedness occurs. There are many theories, some more prevalent than others, but we really don’t know. When is something we can measure. Studies in children show that by 48 months, almost all start to display a firm preference for one-handed or one-sided activities. Under 18 months we all just sorta picked different hands to do things more randomly.",
"I am right eye dominant bat lefty golf lefty hockey stick lefty tennis righty throw righty write righty kick soccer ball complete equal on both sides My immediate family is right handed in everything",
"There is a book titled \"Right Hand, Left Hand\" by Chris McManus which goes into some theories involving the development of handedness. Tl;dr - the body is inherently asymmetric (your heart is on your left side except in very rare cases). In most humans, dominance develops on the same (right) side relative to the body axis. This is under genetic influence (let's call the gene X). Some individuals have a variant of gene X, where the dominant side develops *randomly* relative to the body. These people may be right- or left-handed. McManus goes into molecular theories as to how this may work, which I don't find terribly convincing. There is also some academic literature on hair whorls in relation to handedness. Most right-handed people with a single hair whorl on their heads have the whorl going clockwise. People who are not right-handed have a much higher incidence of anti-clockwise whorls. The authors speculate that the genes controlling hairl whorl direction and handedness are linked: URL_0 I also did a little self-experiment. I was born right-handed. At the start of this year, I started writing and doing all other tasks exclusively with my left hand as if I were left-handed. This includes eating and manipulating objects (ATMs etc). I can write very neatly at normal speeds with my left hand now, such that nobody can really tell the difference between my left- and right-hand script. However, I find maximum writing speed to be the limiting factor. My left just cannot write as fast as my right. I'm not sure if this will eventually go away with more training."
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7kk8k1 | Why is film grain considered good? | Other | explainlikeimfive | {
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"drf1ctx",
"drf0bf1"
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"text": [
"Its the same as lens glare, which was originally seen as a film maker fucking up, its now added back cause it feels more \"real\" In a similar vein, Film grain envokes a feeling that the movie you are watching is old. Cuphead, a video game added film grain because they were aiming for a very early cartoon aesthetic, and cartoons of that time always had film grain.",
"My eyesight is good enough to see the pixels at the cinema, especially in certain tones and in still scenes. I find this extremely jarring and immersion breaking. I stop living the film and instead back in the cinema looking at a screen . I much prefer film grain even if the resolution is lower. It has a much more organic nature and so blends the film together more seamlessly even though there is less to actually see. Noise is a blotch on the film, it is also immersion breaking. When the pixels are finally dense enough I will probably prefer the increased resolution. Some people are also sentimental for the experience of the old format. I evokes happy memories from their childhood when going to the cinema was a more magical time than it is as an adult."
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7kl1vb | How does Chinese water torture work? | Other | explainlikeimfive | {
"a_id": [
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"text": [
"Isn’t that the dripping on your head? If so it’s just you go crazy from the continuous noise and the feeling eventually makes your head stop working but you just go loony"
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7kl5vg | Euclidean and non Euclidean Geometry | Mathematics | explainlikeimfive | {
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"text": [
"Euclidean geometry is geometry as we learned it in school. We can describe the properties of objects or shapes using these mathematics. Euclid proposed a number of what we call axioms, or formal rules, that we know to be true and can use for determining the properties of a geometric object. Non-Euclidean geometry is any form of geometry where the original set of axioms, the original rule book, does not apply. One of the main features of non-Euclidean geometry where conventional knowledge does not apply is in parallel lines. Take a piece of paper and draw a line (assume it goes off infinitely in both directions), and draw a dot separately from the line. Now what Euclid’s rules tell us is that there is only one way to draw a line that goes through the dot, but does not touch the other line. That is a parallel line. If somehow you managed to make non-Euclidean paper, you would be able to draw many different lines that touch the dot but not the other line, _and_ aren’t parallel. What Einstein showed is that spacetime is non-Euclidean, due to the effects of gravity.",
"Euclidean geometry is geometry on a flat surface (normally called a plane). Non-Euclidean Geometry takes place on a different surface (eg the surface of a Sphere). To see an example of the difference: the angles of triangle in the plane add up to 180 degrees. But on a sphere they will add up to more than 180 degrees. To see this, imagine a triangle on the Earth where one side goes from the North Pole to the Equator, another goes a quarter of the way round the Equator, and the third goes back up to the Pole. Each angle of this triangle is 90 degrees, do the total, in this case, is 270 degrees."
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7kl878 | how does spray insulation foam work and turn from spray to foam? | Chemistry | explainlikeimfive | {
"a_id": [
"drfe3ju"
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"text": [
"Inside the can, there is a large amount of gas dissolved in the liquid. This is a lot like C02 dissolved in soft drinks. When you spray the foam, the gas begins to expand (much less pressure outside the can, than inside!) and it makes bubbles. However, the liquid begins to harden before all the gas fully escapes...meaning that the bubbles actually harden while the gas escapes. This creates the insulating foam. There are also \"two-part\" systems... used by professionals. In these, chemicals are mixed together as they exit the containers...and they react producing gases that create the bubbles."
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7klafy | what actually happens in our bodies that gives us the feeling of tiredness or sleepyness? | Biology | explainlikeimfive | {
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"Melatonin in your body breaks down throughout the day while exposed to light and stops breaking down when not exposed to light anymore, thus making you tired. This is why screens can mess with your circadian rhythm (they emit light) If you often feel tired throughout the day, you could be lacking iron which is one of the components for the metalloprotein Haemoglobin which transports oxygen throughout your body Edit: I know that alot of many other factors are involved in sleep (adonosine, tempreature etc etc) but melatonin plays one of the more major roles. Obviously this is simplied but I'm no professor.",
"It’s not all just solely melatonin and nothing else. As a second example, adenosine builds up in the brain that also causes sleepiness. Interestingly, this is the neurotransmitter that Caffeine mimics in the brain, binding to adenosine receptors in place of the adenosine. However the caffeine doesn’t cause the same slowing of the nervous system that adenosine does, hence its stimulant properties and keeping people from feeling the tiredness affects. Many other vitamins and minerals such as Iron and B vitamins also have a role in the feelings of tiredness. Melatonin may be the stand-out, but it’s not the only factor.",
"There's got to be more to it than melatonin. Source: Me an insomniac for whom melatonin does nothing.",
"Lots of misinformation on this thread. Sleepiness at night is a synergistic combination of four factors: (1) buildup of adenosine, which rises throughout the day and dissipates as slow wave sleep is obtained; (2) reduction in circadian alerting signals, which peak hours before bedtime and back off substantially throughout the night; (3) melatonin, which builds in concentration 60-120 minutes prior to typical bedtime and exerts a *mild* sleep-inducing (hypnotic) effect; and (4) temperature, which falls around bedtime and is thought by some to 'gate' entry into sleep (think about how hard it is to fall asleep with cold feet -- research shows the relationship between our core and distal (extremity) temperature maps closely onto sleepiness. And please look into evidence-based interventions like CBT-I instead of relying on Vitamin D or melatonin to treat insomnia.",
"Short version: Melatonin increases during the day. The more it builds up, the sleepier you get. Melatonin production is also influenced by sunlight."
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7klb9l | How does the brush bring shine to a shoe after polishing and conditioning? | Other | explainlikeimfive | {
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"text": [
"When you glob on the polish with the applicator brush it fills in all the nooks and crannies. When you use the polishing brush it removes the excess and buffs the remaining polish into a shine. The hair on the polishing brush is so fine and tightly packed that it gives it that works similar to a buffing rag for autos. For a mirror shine on black leather add a little heat and rebrush or use a very soft cloth.",
"The brush rearranges, smoothes and aligns the waxes by physical force and frictional heat. The shine comes from a uniform and even surface of hardened wax."
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7kld1s | What are jewels in analog watches for? | Technology | explainlikeimfive | {
"a_id": [
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"text": [
"Originally they were placed in [high wear points]( URL_0 ), because their very high hardness allowed them to replace metal components and wear less than the softer metal. Eventually, they succumbed to [Goodhart's law]( URL_2 ), and started being [added as a selling point]( URL_1 ) (the idea being more jewels indicated a more complex movement, but many jewels added later were simply added to increase the jewel count without increasing complexity)."
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"http://barrygoldberg.net/watchguide/jewels.htm",
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"https://en.wikipedia.org/wiki/Goodhart%27s_law"
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7klmnm | How is food flavoring made? | I don't understand how you can make e.g. strawberry flavor without using real strawberries. | Chemistry | explainlikeimfive | {
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"text": [
"Flavor is just a mix of chemicals in the food causing reactions with sensory neurones in the nose and tongue combined with the psychological knowledge that you are about to eat a strawberry. All you need to do is make chemicals that give a roughly similar response (esters are good for this) and convince the brain it is eating somthing strawberry flavoured and it is close enough. Often the fake flavor is nothing like the real (see bananas) but if it tastes nice people dont care."
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7kltwc | Why does sound travel faster in warm temperature? | The reason sound travels faster in solids is that the particles are closer hence faster to pass vibrations to, following the same logic, shouldn't relatively cold gases pass vibrations faster making sound travel faster in less warm or cold temperature? | Physics | explainlikeimfive | {
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"text": [
"The reason that sound travels faster in solids isn't actually because the molecules are closer together. It's because solids are *stiff*. A stiff material does not deform very much when it vibrates, which allows the vibration to travel very quickly. A compressible material, on the other hand, wastes energy expanding and compressing with every vibration, slowing down the wave. In fact, a material with a higher density actually results in a slower speed of sound, because it means that more mass has to be accelerated back and forth with every vibration. This means that the speed of sound in gold (~3200m/s) is much lower than in aluminum (~6300m/s), even though they're of comparable stiffness. So because cold air is denser than warm air, it has a lower speed of sound."
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7klu30 | probably a dumb question but here goes. If someone has lice why exactly can't they just dip their head in water and drown the lice? | Biology | explainlikeimfive | {
"a_id": [
"drfaw2n",
"drfaw0j",
"drfatfc"
],
"text": [
"Lice can survive a long time underwater, about 14 hours. I would imagine that their eggs would survive and repopulate as well. So perhaps you could drown them, but you'd have to drown yourself first.",
"because lice can survive underwater for up to to 14 hours. so unless yer staying underwater with scuba for that long.....",
"It'd be hard to drown lice. But I think it's a good question. *Research has shown lice can survive when immersed in water for 14 hours at 86–98°F.* source: google search"
],
"score": [
14,
7,
5
],
"text_urls": [
[],
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} | [
"url"
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|
7kmgco | How do people like Jeff Bezos—with high net worth tied up in assets and company shares—afford to pay for huge purchases like the Washington Post, private jets, luxury homes, etc.? | Economics | explainlikeimfive | {
"a_id": [
"drfg03s"
],
"text": [
"A couple of different ways: - They sell some of that stock. Major shareholders will regularly sell stock issuances and grants to free up liquid capital - They get dividends based on that stock ownership. Dividends are very common for larger companies, so if you own a lot of stock that can be a major financial windfall - They borrow against the stock in question. Bezos is worth nearly $100B right now - if he asks the bank to loan him $100M for a few years, he isn't exactly a major default risk - it is the equivalent of someone who is worth $100K asking for a $100 loan..."
],
"score": [
3
],
"text_urls": [
[]
]
} | [
"url"
] | [
"url"
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|
7kmm2x | Why does reheated food taste different than freshly cooked food? | Other | explainlikeimfive | {
"a_id": [
"drfhd3e",
"drfw1sz"
],
"text": [
"Dehydration, mostly. Reheating the food destroys what remained of volatile compounds that made the flavors of your meal pop, while also removing more water from it. Sometimes this can be beneficial. It is why things like soups and tomato sauces get stronger and sweeter with a night in the fridge.",
"- Dehydration, the more time the food stays around the more it dries. - The most volatile substances totally or partially went away. Smell makes up lot of flavour, it's the reason why you don't drink beer or wine with a straw: you would lose half the flavour simply because your nose is further; think also about how flavourless things are on a bad cold. - Chemical reactions happen in food: for example fruit ripens even off the tree because enzymes gradually break down complex carbohydrates, which are tasteless, into sweet, simple carbohydrates. Some reactions are fast, some are slow. Cooking basically \"shakes\" everything up and makes lot of new reactions happen, so that the freshly cooked food has a whole new set of substances. Fast reactions happen before you eat it, slow reactions take some time and won't happen before you reheat it."
],
"score": [
9,
3
],
"text_urls": [
[],
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} | [
"url"
] | [
"url"
] |
|
7kmst2 | Why are 3d models used for games, in a T-Pose when not in use or before an animation ? | For example, a lot of games uses this, but I never knew why [example]( URL_0 ) | Technology | explainlikeimfive | {
"a_id": [
"drfiwpz",
"drfo081"
],
"text": [
"It's the best way to model or sculpt it. it's also more or less a standard, so you can easily take a skeleton from another model and place it on your working model. It allows for easier deformation modelling too. You can also model a character with their arms down, but then when you want to animate those arms upwards the deformation becomes a lot harder to get right.",
"Usually these days characters are modeled in [A pose]( URL_0 ) instead of T. The reason is that A pose is a much more natural position for the arms to be in. They are modeled in this pose for a couple reasons, it's easier to sculpt a character in this pose. It's also easy to rig the character in this pose."
],
"score": [
7,
3
],
"text_urls": [
[],
[
"https://img2.cgtrader.com/items/641232/b70e7cc9ba/large/fantasy-female-character-2-a-pose-3d-model-obj-ztl.jpg"
]
]
} | [
"url"
] | [
"url"
] |
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