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7kmx3u | What is mRNA? What is it’s potential and far along in development is it? | Biology | explainlikeimfive | {
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"Super simple here. Say you wanted build something....back in the day you would have gone to the library and found a book that had plans in it. You would have copied those plans and taken them home and built the thing. DNA is the instruction book, the library is the nucleus. Your copy of the instructions that you wrote in your own words and took home are the mRNA, the tools you used to build it are the tRNA, and the final product is a protein That help?",
"mRNA isn't some sort of special technique or pharmaceutical, it is a type of molecule that is a basic step in the gene expression in all living organisms."
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7kmzm9 | How can a food illness get traced back to a restaurant or a specific item being purchased? | Who report the illness to another? When ever I've got food poisoning, I mention it to who ever I speak to next and call it a day once I'm better. If I were to go to the doctors and have salmonella poisoning, who investigates to find out where it came from? | Other | explainlikeimfive | {
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"I used to work in a restaurant. And I actually asked our Main Office Safety Dept about this once. We have a procedure to follow if someone calls and complains about \"food poisoning.\" Basically, it's impossible to track it unless there is more than one occurrence. If someone has eaten/drank anything else within 24 hours, you can't prove where it came from. Aside from that, it takes a day or two before you start showing symptoms. So, you may think you got food poisoning from McDonald's when you ate there today at lunch but in reality, you probably got it at Taco Bell yesterday at lunch. Now, if you have 3 people calling saying they all have Listeria and they all ate there on November 11th, now you've got a problem.",
"Doc will ask questions such add where you've been eating and what you've been eating. Combined with other people who are also experiencing symptoms they can narrow it down.",
"I got salmonella from a sushi place. The CDC called me after I checked into the hospital for it. They called me 3 times I think to interview me about what I'd eaten, and where. They tracked it down to 3 states, all with shipments from what place of one type of fish. It was pretty interesting to be part of the process. I guess hospitals report certain types of things to the CDC to track them. Not interesting enough to go through needing to poo 31 times in a single day. Salmonella sucks."
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7kn76r | How is burning wood different from rotting wood in terms of their carbon footprints? | I am fairly certain that the largest products of combustion are carbon dioxide, water, and thermal energy, but how is this different from rotting wood? Is combustion the same as natural decay, just faster? | Chemistry | explainlikeimfive | {
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"I think the main difference between these processes is where the carbon ends up. In a rotting process the carbon is recycled back into the environment without going into the atmosphere. Some CO2 is released by the microorganisms into the air, but a lot of the carbon is converted into carbs, proteins, etc. In combustion however, nearly all of the carbon is released into the atmosphere as carbon monoxide and carbon dioxide.",
"It isn't that much different. There's a large difference to burning fossil fuels like coal or gas. A tree is part of the carbon cycle of the biosphere. It takes carbon out of the atmosphere to grow, and this carbon will be bound for the lifetime of the tree, after its demise it will be released. Either into the atmosphere, or into other organisms. Some of its carbon will end up in carbon traps, for example bogs or the deep ocean. It doesn't matter that much whether you fell the tree and burn it, or let it rott. The point is there are other organisms that can use its carbon. The carbon dioxide levels of the atmosphere will raise only shortly, until the carbon is taken up again. Carbons from fossilized fuels on the other hand are inserted into the carbon cycle additionally, they where part of it millions of years ago and have been removed from the cycle for good - if it weren't for human interference. These lead to problematic consequences, i.e. raising CO2 levels in the atmosphere or the oceans."
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7kngwy | - Why do our eyes become bloodshot when we're tired? | Biology | explainlikeimfive | {
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"The whites of our eyes are filled with blood vessels that swell up and become noticeable when the surrounding cornea and eye tissue are lacking in oxygen. If you have a lack of sleep you're body is in need of rest, especially your eyes. Sleeping also protects the eyes from becoming dry and irritated which will result in redness as well. Additionally, being awake for long periods of time means there is more time that you are actively using your eyes, generally the more strain put on your eyes means more pressure resulting in the inflammation of the blood vessels in the eye.",
"And high, why do they become bloodshot when I smoke?"
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7knj2l | how do eye dilation drops inhibit the parasympathetic nervous system? | What exactly do the dilation drops do in the parasympathetic nervous system? I've seen a post about it not to long ago but it didn't go into much detail. Could someone please explain it in more detail? Thanks! | Biology | explainlikeimfive | {
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"The pupil is closed by ciliary muscles (round muscles around the eye), which are stimulated to contract and close the pupil by parasympathetic innervation. This signal is sent through certain receptors (muscarinic receptors). The chemical agent in eye drops bind to this receptor, but they don't cause a contraction, so they prevent the pupil from closing. The dilator muscles which open the eyelid have no opposition, so every time they open a little bit they stay open and are unable to close."
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7knlvq | What is happening to the body/brain of a person who has taken a dose of LSD? How does LSD cause hallucinations? | Biology | explainlikeimfive | {
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"People take for granted how much our brains fill in the blanks visually when we are perfectly sober. The input our brains get from our eyes actually contain a big [blindspot]( URL_1 ), and a spiderweb of veins that block our vision. Our brains are rather talented at guessing what is there based on what is around those bind spots and what it knows about the world. It happens so seamlessly that we don't even notice. Ever see something in the corner of your eye like your dog sitting there, but when you look it's just an object that is somewhat the shape of your dog? Your eyes caught some vague shape, your brain guessed that it was your dog based on your expectations, but just happened to be wrong this time. On LSD, these functions become far less good at their job, but they're still trying to fill in those blanks. Once a white cat came to lay on my chest while I was looking up at the popcorn stucco ceiling, and the ceiling became a kaleidoscope of cat faces. If I focused on any one face, That face disappeared, but my peripheral vision was full of smiling purring kitties covering everything white in the room. [Google Deep Images]( URL_0 ) come very close to conveying what this is like.",
"From what I understand LSD does not actually produce literal hallucinations. It does not create items that do not exist in some way but only distorts things that are there. LSD style distortions look like the ones you can see from hypno disks like this URL_0",
"LSD and other psychedelics latch onto a receptor sites called \"5-HT2a\" which affects the neurotransmitter serotonin. LSD in particular effects a lot of other 5-HT (serotonin) receptors and even some dopamine receptors, but 5-HT2a receptor sites, in particular, is what is believed to produce the hallucinogenic effects of psychedelic drugs. These receptors also affect many other functions in your body and some psychedelic drugs (like the 25-NBMOe series which is more selective and a \"full 5-HT2A agonist\" (means it hugs onto the receptor harder in certain spots)) can cause all sorts of effects beyond hallucinations such hyperthermia, hyperpyrexia, tachycardia, hypertension, clonus, seizures, agitation, aggression, and even death. LSD (and many other psychedelics) for some unknown reason don't cause these effects (which are symptoms of something called serotonin syndrome). The why behind the hallucinations caused by the 5-HT2a receptors is fairly unknown, but the most popular idea is that stimulation of this receptor causes a \"sensory feedback loop\". Normally your brain takes sensory input, such as light entering your eyes, and runs it through a process in one section of your brain (the thalamus) and fed to another part (the cortex) where it is experienced by you as sight. When on a drug like LSD, that sensory input is not just run through the process once, but is fed back to the start of the process and run again and again. This reprocessing of the original sensory data causes distortions that you experience as hallucinations. tl;dr, your brain is re-processing and distorting data it receives many times before sending it to the place in the brain where you actively experience the data.",
"From what we know at the moment your brain basically tries to crosswire a bunch of stuff while the lsd is active.this is the trip, and you can tell if you get synwsthesia see visuals etc. Just your whole brain using all kinds of pathways at once. The PNS response, (the body response) is kind of akin to a fever but mentally wired. Your sense of temperature is all messed up, so you sweat feel cold etc, and the seratonin surge can make u feel good sometimes. You might get an adrenaline rush, or just everything feels weird to the touch. If you take enough you can surpass a lot of this, to thw point where you are tripping so hard you dont even realize your body anymore, because your so focused on the incredible trip your mind is going through. Fun stuff. Dont bite off more than your brain can chew, some people just flip at that point.",
"Oh man I am so glad for this question because I literally just wrote my thesis about this. What you consider to be normal vision is already a hallucination. What you \"see\" is a jumble of very simple shapes. In the human visual area, these shapes are put together in a stage-by-stage process. Certain shapes occurring together will become an assortment of shapes, and certain assortments occurring together become conglomerates of shapes, and conglomerates occurring together become even bigger assortments of shapes, all the way up to actual objects. In a sense, your entire reality is fabricated, but luckily this fabrication is pretty accurate, but still a fabrication. On LSD, this fabrication progress is in parts broken down and altered. Many of the kaleidoscopes, geometric shapes, fractals, etc. people see, are actually stages of this fabrication process transmitting information repeatedly, or even transmitting \"templates\" without input. Much of the geometry itself is also a reflection of the structure of the human visual centre itself. The shape of our retina and our eyes is also reflected, and our \"blind spot\" can become the centre of an endless tunnel or vortex. But, LSD also creates another kind of hallucination in another way. By rerouting information from different parts of the brain TO the visual centre, we start to experience hallucinations that are actually representations of different elements of our mind. What we experience as hallucinations, is the visual centre trying to process the information that is routed to it, whichever it may be. What LSD ultimately shows you is parts of yourself, things that happen in your brain 24/7 but that you ordinarily don't have access to, or direct access to. If anyone needs sources on specific parts of this (since all this stuff is still quite controversial) please ask.",
"What’s the worst form of bad trip can happen when you take it or take bad lsd?",
"This post is about lysergic acid diethylamide. Not psilocybin. The highs between the two have similarities but are completely different. Please do not confuse OP with anecdotes unrelated to the topic.",
"Internet Pirate stealing a neurobiologist answer here. Nothing posted so far has an adequate, yet dumbed down explanation of what goes on, so I'll give it a shot. The first thing we need to establish is what a neurotransmitter is. Essentially, there are chemicals that exist within your brain that help transmit and modulate information. This happens by the chemicals binding to a site, similar to a lock and key, where the key (neurotransmitter) unlocks a lock (receptor) and this lets the brain know that certain information was exchanged. This information typically releases something known as an action potential, or essentially an electrical signal - basically it lets another part of the brain know that this part of the brain was 'activated'. There are only so many neurotransmitters and they can do a variety of things in the brain. LSD, or lysergic acid diethylamide has a structure that is very similar to a few neurotransmitters that are naturally produced. The key it is most similar to is a neurotransmitter known as serotonin. Serotonin is used to modulate and signal a variety of things in the brain. Visual processing (or what you see) utilizes a lot of serotonin. Almost all of the senses have some serotonin input as well. Emotional processing (sad, happy, excited, etc.) is also heavily serotonin influenced. LSD happens to be even better at activating serotonin receptors than serotonin itself, so it essentially increases the normal levels of signaling by serotonin (it does this through a variety of mechanisms, not just limited to better binding - it actually releases extra serotonin, changes the lock to accept keys more readily, etc.). In a lot of ways its like turning up the volume on quiet music. Not only are the already audible pieces more audible, but things you previously could not hear are now audible (whispers you might have missed, or background noise might now become audible). Because it increases the signal, it also increases the signal noise (if you turn the volume up on a microphone very high, you sometimes get feedback loops, or that annoying high pitched noise). In addition, if you have the volume extremely high, you may not be able to differentiate between the louder sounds very well. On LSD, this often results in hallucinations - hearing, seeing, touching, tasting, etc. things that are not actually there. In addition, through a relatively unknown mechanism, LSD increases 'cross-talk' between areas of the brain. That is to say, it helps stimulate areas of the brain that don't normally talk to each other, to start talking to each other. Over the long term, it can even help create connections that previously didn't exist - much like putting up extra telephone or internet lines. This increased cross-talk while under the influence of LSD (combined with the increased sensory input) often results in something known as synesthesia, or a mixing of the senses. What this means is that people might experience a sense across multiple senses - they might see sound, taste colors, or feel smells. Since the mechanism of cognition (what causes us to think the way we do) is not known, I cannot explain why it changes a person's mindset, only that it does. People often describe it as 'thinking outside the box'. Having done LSD myself many times, I agree that it shifts the paradigm of thought. It likely is associated with this 'cross-talk' mechanism, at least to some extent, but the increase in serotonin and dopamine likely has an effect as well. Other serotonergic drugs, such as ecstasy (which is very similar to hallucinogens), shift how you think as well because increased serotonin results in a sort of euphoria (happiness). It also seems to increase one's ability to empathize with someone else - that is to say, you more easily relate with someone else's emotional state. This increased empathy also changes how you think about things. It's important to note that no hallucinogens have any proven addictive mechanisms (they are the only recreational drugs that have no addictive qualities). In addition, casual use is not associated with any permanent brain damage. Any use, casual or not, will reduce the relative abundance of serotonin (and other catecholamine receptors, such as dopamine) receptors. However, anecdotal evidence suggests that a single use of a moderate dose can be recovered from within about 1-2 weeks of abstinence."
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7knyu5 | - How digital clocks stay synchronized together | I was talking to my friend about computer clocks and I began to wonder how computers or phones stay synced together with their time. Are they connected to a server, or do they ever refresh for clock error? How does this work? | Technology | explainlikeimfive | {
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"The Internet is not just HTTP for websites. There is a separate protocol, NTP for [Network Time Protocol]( URL_0 ) (those Internet folks are sooo creative), which lets distributed computers agree on an accurate time. More accuracy means much more work, so most computers are not that precisely synchronized.",
"There is a protocol called Network Time Protocol which can be used to synchronize clocks. Most modern operating systems have it configured by default. In addition, anything with a GPS system in it can synchronize time based on GPS Data if it has access to at least 4 satellite signals at once. GPS is kind of special in that exactly 3 signals and already having the exact time will give you your exact position, but you can use a 4th signal instead of the time, and then get your time out of it.",
"For the United States the agreed upon timing standard is the US Naval Observatory or UTC(USNO). Each day as the GPS constellation is updated, tiny correction factors steer its timing signal towards UTC(USNO). Since the GPS signal is universally available, UTC(GPS) is used to steer most other methods of timing distribution through ground based receivers that are placed at precisely known locations. Since these receivers \"know\" where they are and \"think\" the GPS message is definitively accurate they can use it to steer their timing to match GPS then rebroadcast it to their customers. This allows NTP, NIST, the cell towers, NASAs ground based antennas, the Department of Commerce, and virtually every other networked clock on Earth to broadcast and utilize an accurate and synchronized time.",
"In addition to the methods mentioned, devices can maintain their current time when turned off through the use of a battery. This battery is usually a watch battery in computers, and functions to maintain some basic system setting as well as the time.",
"Standalone digital clocks don't stay synchronized at all. Computer clocks typically get their time over the internet. See, e.g., URL_0 As for cell phones, they also get their time over the network. The exact methodology for getting the time differs by network type, but it's the same basic idea--it gets the time from a central source. A GPS device (e.g., a GPS watch or a navigation display) receives the time from the GPS satellites, which are constantly broadcasting their current time."
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7ko15l | What makes a scientific study a good one? what are the best practices? | Like, control groups, placebo, whatever. I don't have much knowledge about it. And how to check when some study seems reliable but it's actually flawed? Thanks. | Other | explainlikeimfive | {
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"It's almost impossible to tell if a study is flawed, unless you are an expert in the topic. Instead you could see if the results have been replicated by other people. By the time you see 3-5 papers published that confirm a result, that's pretty good evidence that the study is true. It's also **super important** to read the actual scientific study, even though it might be really hard to decode, because the \"science news coverage\" is likely to be wildly different than the actual paper that was published.",
"I think what you're asking about is study design. Your question is a bit open-ended so it would be hard to answer completely here. You can [learn more about study design on khan academy]( URL_0 ). There is a lot to know about good scientific practices, and much of it follows from basic logical and statistical reasoning. The basics are like this: You start with an idea about some specific observable cause and effect in the world. For example, you predict that a new drug will help alleviate migraines in most people. You set it up as a **falsifiable statement**, like this: The null hypothesis is that the new drug will have no effect on patients. The drug is only useful if your experiment shows that the null hypothesis is unsupported. I know, the wording sounds confusing, but its meant to be very specific. So you gather a large group of people (you can determine through statistics how large that group should be) in order to test the new drug. There are a lot of things that can affect a headache that we don't know about. There are some things that can affect it that we do know about. Without accounting for these things, we might end up concluding something that isn't true. We want to try to account for these variables as much as we can in our study, so we have some methods of doing this. To simplify the idea of an experiment, there is a **control group** and a **variable group**. The variable group for our study would be the people who take the new drug. The control group would be those who don't take the new drug. This is important because we want to study the difference in reaction between the two groups to the variable (the new drug). But what if by simply taking a pill, some people feel relief, regardless of whats in it? ([the placebo effect]( URL_1 )). Well, you can do a placebo-controlled study where everyone takes a pill, but only some of the people are taking the new drug. None of the test subjects know which pill is which. This kind of experiment is called a **blinded trial**, because the test subjects are unaware of the control and variable groups. But what if we know that the scientists giving out the drug and the placebo tend to have a bias in who they hand the placebo to? We can mix up all the pills so that even the scientists don't know which is the real drug. This is called a **double-blind trial**. (There are ways to make sure who actually took the new drug and who didn't, afterwards). There is so much more to learn and it is all important and useful to just about anyone, even if you aren't a scientist. The more you know about scientific studies, the more you can learn for yourself without relying on others' conclusions and assumptions.",
"It's pretty rare that what's flawed is the study, what's a lot more common is that the media draws conclusions that the study does not make (and that the authors do not make). When in doubt, go to the actual study, and you will usually find that the authors have been careful to outline their technique and its limitations.",
"The other two answers here are great, and accurate, but the best practice for determining if a study was any good is peer review and replication. If the study was flawed or biased, a good peer review and an attempt to replicate will suss that out.",
"The gold standard is [reproducibility]( URL_0 ) Can someone else, using the experiment you designed, arrive at corroborating conclusions? If not, your conclusions mean bupkis. A key to this is making sure you have a large enough sample-size to reach a meaningful conclusion and aren't just drawing spurious conclusions from a limited data set."
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7ko4ax | What is an enterprise architect? | My dad can't explain his job to me. If it helps, he is also knowledgeable in SAP, which is another thing I don't understand. | Technology | explainlikeimfive | {
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"SAP is a company that makes a suite of tools, generally around accounting and human resources. Just like Microsoft Office has Word, Excel, PowerPoint etc. SAP has something to process people's paychecks, the company's bank accounts and generating expense reports. The architect's job is to connect all these different systems together. So when someone personally get's paid that goes through SAP's paycheck program, however it also sends a note to SAP's expense report program saying \"hey add $1,000 to the employee expense line\" and another to the bank saying \"hey withdraw $1,000 for John\". In many ways the enterprise architect is more analogous to a city plumber (which is also a civil engineer). They make all the connections between different systems, the same way a city plumber has to connect people's houses to the main sewer system and then route that to a repository.",
"his role is to make sure that all the big pieces of the corporate software picture fit together and work. whether it be the SAP system that tracks logistics, ties in with the accounting system, ties in with the CRM system like salesforce or any other internal and external business systems. additionally, his role might cover that any programmers working under him are following best practices and keeping up to date on technology and security concerns."
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7kodr0 | Why did variolation/inoculation of smallpox acquired from sores have a less severe infection than naturally acquired smallpox? | Biology | explainlikeimfive | {
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"The \"donor\" scabs/sores were usually taken from a person with a mild form of the disease. After that, they were dried out and/or mixed with other chemicals, to further weaken it. So the patient ended up receiving only a very weak dose of smallpox. More than that, the procedure meant that you could wait until the patient was in good health before infecting them, ensuring that the patient had all their strength to fight off the disease, unlike natural smallpox which might happen to strike when they were sick with something else."
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7kokl3 | Why do most hard candies just shrink down as you suck on them but peppermints get all porous and full of holes? | Chemistry | explainlikeimfive | {
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"I can't find the YouTube video I'm thinking of, but [this one]( URL_0 ) (link should start right about the time they're \"whitening\" the white part of the candy cane) gives a good fast-forwarded example of the process. Basically, to get the candy to look white, the candy is folded many, many times, trapping tiny air bubbles which makes the candy look white. Then, as you're sucking on the candy, your saliva dissolves the microbubbles until you have little bubble craters in the candy.",
"Because most hard candies are a solid structure of sugar -- as you strip off the outermost layers of sugar, you reveal the next layer down. Peppermints and a few other candies are actually filled with holes, so as you dissolve the outer layer, you get a new layer that also has holes. And then you have candies like Mentos where the outer layer is peppermint with all its holes, but this is on top of a candy layer that has no holes... so as you suck on it, the holes disappear.",
"congrats on this question which i never would have thought of as a scientific query in the realm of materials science your question relates to science of cooking candies are not all made the same way. some are homogeneous and continuous, and some have air mixed into them to make an inhomogeneous bubble like structure. it's the latter that will form a sponge if you dissolve some of the sugar. there are several books that talk about the physics and chemistry of cooking (just google) and will give many other examples. for example, angel food cake versus cookies, etc. many physical variations based on processing differences.",
"I don’t think this is so much a chemical process as a production process. No one has really touched on how peppermints are made. They are a pulled candy. As the hot candy is cooled it is pulled on a big hook or machine which aerates the candy, turns it from clear to opaque and creates strands of candy, thereby packs hundreds of strands into a single stick or drop. [This video explains how handmade peppermints are made]( URL_0 ). The music is... not great... but it gives you some insight into how peppermint sticks, canes and candies are created.",
"In order to make peppermints white, they are pulled on a candy hook. This pulls tiny air bubbles into the hot sugar, refracting light until the entire thing becomes opaque and white. As the candy dissolves in your mouth, tiny pores merge to become larger and larger. The direction the pores go in indicate the direction the candy was pulled.",
"Peppermints have bubbles folded into them while hot durring the cooling process. They are just bubbles trapping in the candy.",
"They are pulled candy and have long skinny bubbles running in a certain grain through them. It's easier for saliva to permeate these holes to eat away from these cross sections of bubbles outwards.think of it as the spit making these bubbles bigger while the candy shrinks.",
"Because to make peppermint you pull the cooked sugar and fold it over and over again until you can knock it on the counter and it makes a sharp noise. That's when you roll it into the thin cylinder and make the desired shape. The pulling and folding adds tiny air pockets into the sugar, but when you roll it into the shape the outside gets smooth. So when you start sucking it's smooth, but then when you get the middle area you get the air pockets you made.",
"Follow-up question: How come peppermint breath mints become porous while peppermint candy canes become miniature stabby death-sticks?",
"Btw, any suggestions for non-sour hard candies? (Jolly ranchers is too sour for me, except the watermelon flavor).",
"I'm no materials scientist but this sounds like a solid example of bulk erosion vs surface erosion. Bulk erosion is the peppermint case, where the saliva penetrates rapidly throughout due to the bubbles formed in the cooking process and erodes the entire material. Hard candies are more resistant to saliva penetration and so only the surface erodes.",
"Most hard candy like a jolly rancher is poured or just sized and cut from a slab, candies like starlight mints and some cut rock candies are pulled to incorporate air this makes them a bit lighter and more opaque. This is when you get the holes when sucking on them. Things like altoids are cut from a fondant dough, and after dinner mints are a grained candy. If you want to talk more candy science please reach out, I do this for a living. Edit-added a bit more detail",
"Why do most hard candies just shrink down as you suck on them but jolly ranchers slice open your god damned tongue?",
"My dad worked for Lifesavers and worked on Lifesavers mints, so I've learned a thing or two about this. Peppermints often start out as a powder that is pressed together with a lot of force - I've even watched powder go into machines and mints come out. As you suck on it, the powder comes apart a bit. In contrast, hard candy is a basically a hardened syrup goes into the machine in the same texture that it comes out, just pressed into a shape. As you suck on it, that syrup melts."
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7kom4u | Why does twisting a damp sponge get more water out than just squeezing it, without having to apply anywhere near as much force? | Physics | explainlikeimfive | {
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"It has to do with the area where the force is applied. Squeezing (or compression) will be applied in the area immediately in contact with your hand. Twisting (or torsion) will carry the tension as angular moment throughout the whole surface of the sponge."
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7kowjb | Now that it’s back in season, where’s the flu been? | How do viruses just appear again? | Biology | explainlikeimfive | {
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"There are many different explanation as to why there's a flu season (a surge in influenza cases around a certain time of year), such as: * People spending more time indoors, and subsequently in closer proximity to one another. * Less exposure to ultraviolet light that could damage/destroy the influenza virus before it can infect someone. * Cold temperatures drying up mucous membranes (reduces body's effectiveness against respiratory viruses) * Cold temperatures preserve the virus longer on surfaces people come in contact with. * Less Vitamin D production in the body leading to a reduced immune system. Research in Guinea Pigs has shown that the virus is more efficiently transmitted in cold, dry air than in warm/humid air, and that it has a casing that hardens in colder temperatures (the casing typically melts in your lungs, but obviously it is degraded in higher temperatures, too). Also, there's no hard start date for the \"flu season\", it's just a general term to describe the time frame in which doctors and scientists observe an uptick in flu activity. It's not attached to any set calendar date.",
"It lives in people and animals -- just in smaller numbers when it's not \"in season.\" It does't go 100% out of circulation.",
"It's actually the fault of all the ducks living in China. As many have noted here already the virus is with us year round and a number of environmental factors tend to influence rates of infection. However, the virus constantly mutates in this instance the largest reservoir of the influenza virus is water fowl living in parts of China. You have no doubt heard of bird flu or avian influenza, that is the strain of the virus that naturally lives in birds, ducks, geese and chickens mostly. as such it mutates and occasionally one of those mutations crosses over to infect humans. This goes on fairly constantly and it typically takes 3 to 6 months from the point where it emerges in China to the point where the rest of the world is infected. Your vaccination only works for one season because the next mutation comes along and the old vaccine is no good. the people who make the vaccines are always out sampling for the next emerging strain and attempting to guess which one they need to make a vaccine for, that is also why on occasion the efficacy of the vaccine is low, they guessed wrong. Not all strains are equally potent, about every 100 to 120 years a really nasty deadly strain emerges, the last very bad occurrence was in 1917 the famous Spanish flu that killed more people than WW1 that was occurring at the same time. back then there were no vaccines and people tended to die very quickly (24 to 48 hours). the outbreak went around the world but not all parts of the world were impacted at the same time. Once you have been exposed to a specific strain your natural immunity takes over and you are not likely to be reinfected with the same strain. But next years version could easily get to you. There are a lot of variants of Influenza A, Pigs, Horses, Seals, and even cats/dogs many of them can cross over.",
"> How do viruses just appear again? Influenza as with other infectious diseases is always around in someone, but only becomes more prevalent during certain seasons when it spreads most effectively.",
"It's always there. It's just like fresher's flu. You get it because suddenly you're surrounded by thousands of people and thus more likely to get the flu and spread it.",
"I don't have a source except my Bio 101 teacher told me the reason why there is a new flu vaccine every year is in part due to international travel. The flu progresses during winter in another part of the world while it's summer here and during this time mutates. Then during our winter when everyone is more susceptible we all start getting it and it mutates here, etc."
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7koy59 | What is unique about sunlight that our bodies need to produce Vitamin D? | Biology | explainlikeimfive | {
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"The UV light from the sun acts as a catalyst that allows a chemical reaction to occur that results in vitamin D being produced. The reaction requires specific wavelengths of light to occur, which the sun produces. Artificial UV light that corresponds to the correct wavelengths could also be used."
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7kp5dw | What causes depression and how do we stop it? | Biology | explainlikeimfive | {
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"The problem is easier to understand when you break it into pieces instead of trying to understand the whole thing. Broadly, there are psychological mechanisms and biochemical mechanisms. Psychological mechanisms include cognitive (what you think), behavioral (what you do) and affective (how you feel) aspects. Cognitive side, there's toxic thinking styles (perfectionism), behavioral side there's poor sleep and poor sunlight exposure, affective side there's lack of skill with emotion regulation or contexts that are chronically stressful. Biochemically, there are vague brain regions that seem to be associated with depression and some relationship to neurotransmitters and density of certain kinds of receptors (which is genetic). It's pretty poorly understood, though. We know some medications help, but not necessarily why. And on top of all this, there's a big chicken-or-the-egg problem. Are these differences causing depression or is depression causing these differences? Is it the same for every individual? Why do some people cope and others have a harder time? So as of right now, treating depression comes down to a litany of potential recommendations and potential medications. For any individual, one, a combination, or none of these may work. But overall, there's a few clear patterns: 1) emotion regulation training is useful, including teaching people more about what emotions mean and what they're for and that depression itself isn't a kind of \"insanity\" 2) people with very severe depression benefit from medication that decrease their symptoms first, because they don't really have the resources to try more active coping strategies 3) once people are stabilized, some combination of these coping strategies will help them, even if they relapse (which is likely) and 4) social support is one of the biggest protective factors from developing depression at all and helping you once you do have it.",
"They don't know yet and they don't yet. They have kind of worked out brain chemicals causing it sometimes and pills to regulate the brain chemistry, but clearly it's not as easy as it sounds and it's different for different people.",
"Longer version To start off, lets mention an interesting facet of depression. One of the symptoms of depression in almost all patients is anhedonia, or the inability to feel pleasure or reward. In the brain, the classic \"reward\" transmitter is dopamine, so it would make sense that increasing dopamine transmission in the brain somehow would increase the reward the brain feels, and help alleviate a major symptom of depression; this just isn't true. Out of all of the antidepressants, the only one that I know of that directly works to increase dopamine transmission is Wellbutrin. Instead, the vast majority of the antidepressants on the market work by increasing serotonin transmission. **So if antidepressants don't work by elevating mood (which is what dopamine does), then what does it do?** It turns out that antidepressants probably work by protecting people from the depression-inducing effects of stress. *How do we know this?* Both clinical and experimental psychologists have come to the conclusion that stress causes depression. Clinical psychologists have reported that if people have a lot of stressful events in their lives at once, they have a greater chance of being depressed. Experimental psychologists have figured out that if you consistently place rats in unavoidable stressful situations, they develop learned helplessness, which has similar symptoms to depression. For example, if rats are given the opportunity to stimulate their ventral tegmental area (VTA), they'll do so. This is because there are lots of dopamine neurons in the VTA, and, as mentioned before, dopamine is the primary reward transmitter in the brain. It turns out that if you expose rats to chronic stress, they stimulate their VTAs less-- ie, they feel less reward. However, giving them an antidepressant will reverse this effect. Giving antidepressants to non-stressed rats, however, will not increase the rate of VTA stimulation. **This goes to show that antidepressants don't increase the rate of reward, but instead block the effects of stress. But how?** Since most antidepressants increase serotonin, it makes sense that depression probably affects areas with a large number of serotonin neurons. **Where in the brain are serotonin neurons located?** Turns out that lots of serotonin neurons are located in a group of structures in the brain that we call the limbic system, which is heavily implicated in emotions. One major structure in the limbic system is the hippocampus. And indeed, not only are there major serotonin pathways in the hippocampus, there is a negative correlation between the size of the hippocampus, and the amount of time that an individual has been depressed. So the idea is that stress somehow shrinks the hippocampus, which causes depression. Before discussing things any further, we have to be familiar with a feedback system in the brain called the hypothalamic-pituitary-adrenal axis, or HPA axis. To keep it short, stress triggers the HPA axis, which ends up releasing a hormone called cortisol, which acts on the hippocampus. There are two major hypothesis of how depression affects the hippocampus. **Hypothesis One** This hypothesis was first proposed by Dr. Ronald Duman at Yale University in 1997. He proposed that an increase of cortisol in the hippocampus causes a decrease in a protein called \"brain-derived neurotropic factor\", or BDNF. He claimed that a decrease in BDNF causes the death of neurons in the hippocampus. *Under this hypothesis, the antidepressants work by increasing the serotonin in the brain, which somehow increases BDNF production, and decreases the harmful effects of cortisol* **Hypothesis 2** This hypothesis was proposed by Dr. Barry Jacobs at Princeton University. We know that despite what a lot of people are taught, new neurons do grow in the hippocampus. It turns out that cortisol will decrease the rate of neurogenesis in the hippocampus. His idea was that decreasing cortisol through serotonin transmission will increase the rate of neurogenesis, and that somehow decreased neurogenesis results in depression. *Under this hypothesis, antidepressants work by decreasing cortisol through increased serotonin, which increases neurogenesis* This hypothesis is supported by the fact that stopping neurogenesis in the hippcampus will block the effects of antidepressants. --------------------------------------------------------------------------- Throughout all of this, I'm aware that there are lots of unanswered question. How does serotonin do any of this? How do changes in the hippocampus result in the behavioral symptoms of depression? We know that blocking other areas of the HPA pathway so that cortisol isn't released in the first place doesn't really work in stopping depression. Why? We don't know. We know that ketamine, a recreational drug, has antidepressant qualities. Why? We're not sure, but there's an idea that it increases BDNF in the hippocampus. There's so much unanswered in behavioral pharmacology, and the answer I gave focused more on neuroscience than on psychology. In almost every major drug that we use, we don't really know why it works. there's something unsatisfying about that, but something exciting too. I know my answer ran really long, but I tried my best to give a concise yet thorough answer."
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7kp9o9 | Why do medications tend to give us the same common side effects (ie nausea, dry mouth etc.)? | Biology | explainlikeimfive | {
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"Your body is connected and built on a foundation of systems which all communicate and respond to each other. Changes in one system tend to cause responses in many others. Nausea, dry mouth, and other common side effects are usually caused by changes in the sympathetic (fight-or-flight) and parasympathetic (rest-and-digest) nervous systems. This is important, because many medications influence these two systems either directly or indirectly. For example, nausea and dry mouth *usually* come from stimulation of the fight-or-flight system. When your body is \"stimulated\" this way, you shut down certain functions to focus energy elsewhere. We use drugs like pseudoephedrine for colds, or Adderall for ADHD, and these all activate that system. Beyond that, lots of other drugs will increase fight-or-flight in a roundabout way. Indirectly, any treatment that makes a difference is probably going to have some influence on how \"fight-or-flight\" or \"rest-and-digest\" your body is.",
"Because those common side effects are so common that people often develop them even when it's not the medications fault, but they have to put it as a warning on the label anyway. Also, the body only has so many ways to respond. Nausea and dry mouth just happen to be repetitive ways bodies respond to chemicals."
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7kpalk | What are Lagrange points and how do they work? | Wikipedia has failed me in making the concept understandable. | Physics | explainlikeimfive | {
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"It's 1am here so this might be a little oversimplified and weird; lagrange points are points in space where gravity of different celestial objects cancel out. You might know that larger masses cause a larger gravitational pull. Also, gravitational pull is quadratically inverse to distance, meaning the further away you are from a body the less attraction you will feel. At certain points in space gravitational pull of objects will cancel out because the masses and distances are just right. E.g. There are lagrange points between the moon and the earth. The most obvious one is l1 (lagrange point 1). If you draw a straight line between the center of mass of the earth and that of the moon you will find l1 lies on this line (a couple thousand kilometers from the moons center of mass). Hope this helps and my spelling is not too shit",
"There are five Langrangian points in a two body-system and they all work in different but similar ways but they do all have one thing in common, an object in these point share orbital speed with the small body around the larger body. To understand these you must first understand that orbital speed depends on mass and distance. The first L point is the easiest to understand and is located between the two bodies. If we place an object closer to the large mass it will have to orbit faster to not spiral inwards, but because the smaller mass is further out that mass will pull the object outwards a little bit and will therefore decrease the orbital speed. The second L point is located a little further out than the small object. Because it's further away from the large mass it should require a slower orbital speed than the small mass, but since the small mass is also pulling the object inwards the orbital speed becomes faster. The third L point is located a little further in than the small body, but on the other side of the large body. The combined mass is higher so one might think intuitively that it should be further out than the small body, but accurate calculations show that is not true. The fourth and fifth L points are symmetrical and lie in the orbit of the small body but a little further ahead or behind. The two bodies and the object will form an equilateral triangle and the reason these two L points exist is that once again the gravitational pull of the two bodies cancel out to give an orbital speed equal to that of the small body. Of all these points only 4 and 5 are stable."
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7kpap7 | If blood only flows through our veins and arteries, why do small cuts that don't sever any of either still draw blood? | Biology | explainlikeimfive | {
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"URL_0 There's a lot of tiny vessels in our skin.",
"Because your initial premise is wrong. Blood not only flows through veins and arteries, it also flows through capillaries; tiny blood vessels that more or less permeate the body."
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7kpmv2 | What's the difference between an anti-hero and a villain? | Other | explainlikeimfive | {
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"A villain is an inherently bad or evil character. He exists to do bad things, that is his goal. An anti-hero is someone who is not inherently a \"good guy\" - he does not have \"heroic\" traits, he might not even have good morals. An example of that might be a drug dealer (immoral and engaged in illegal activities that hurt people for the sake of money) who discovers that a rival gang is selling a dangerous drug that is killing people and drawing the attention of the cops. He sets out to destroy that gang - in the process saving the lives of those who would have taken the drug, even though he might have only done it for the sake of protecting his territory. A ... less drastic example. Darth Vader in Star Wars is a villain - he serves an evil emperor and kills people to maintain an iron rule over the galaxy. Han Solo is a type of anti-hero - he's a self-serving galactic smuggler who really only signs up to help out Luke and Obi Wan for some money.",
"An anti-hero is a protagonist -- the main character whom you want to win -- even though he lacks some qualities of a hero and is in many ways not a good person. A villain is an antagonist -- the character you want to lose, because he opposes the main character. Typically evil, but not always.",
"An antihero is a person who the audience or reader is supposed to identify with or support as a protagonist, but who doesn't have typical heroic qualities. Usually they're either doing the right thing for the wrong reasons or they're doing bad things for the greater good, whereas a typical hero is just doing the right thing. Think of The Godfather - the main characters are criminals and murderers, but we empathize with them and their situations, because they have some good motivations along with the bad. A villain is just a villain - they're the bad guy, they're the obstacle in the hero's way, and the audience or reader is not meant to support them, though they may have some empathy built in."
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7kps7e | Why is there a season where the flu is more predominant if it's all viral? Why isn't it year round am issue? | Biology | explainlikeimfive | {
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"text": [
"During the winter people tend to spend more time indoors, which means more time clustered closely together where viruses can spread easily. During the middle of summer in the northern hemisphere those viruses are going wild in the southern hemisphere, for the exact same reason. It's also the reason for the presence of kennel cough, an upper respiratory infection in dogs that happens very commonly when dogs are kept close together in large number, such as a kennel."
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7kpuu1 | Why do song vocals get stuck in our heads so much easier than instrumental parts? | Biology | explainlikeimfive | {
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"text": [
"I get instrumental parts stuck just as easily.... not sure everyone is the same in this regard. Just think smoke on the water.... crazy train... under pressure... I can think of tons of instrumental parts that get stuck"
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7kpvee | Why does THC in edibles take around an hour to have noticeable affects on the body, but caffeine acts almost instantaneously? | *effects | Biology | explainlikeimfive | {
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"Caffeine is water soluble. That is it dissolves in water. THC is not, it is fat soluble. Water soluble chemicals can move from the GI tract into the blood stream much faster than non water soluble chemicals. Many water soluble chemicals such as alcohol and caffeine can actually pass right though the stomach wall right into the blood stream. THC on the other hand will need to get to the small intestine before it can be absorbed.",
"Last weekend I ate a very powerful pot brownie. An hour and a half later I wasn't feeling anything so I ate the fruity pebble rice krispy treat edible. I ended up so high that I was listening to people speak English and it sounces to me what English sounds like to someone who doesn't know it. Then I fapped and went to bed..."
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7kpxg2 | Why does talking to yourself make you think more strategically and/or tactically? | Biology | explainlikeimfive | {
"a_id": [
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"text": [
"Explaining things to yourself is a very common debugging technique. I think they call it the rubber ducky technique, where you pretend to explain your code to a rubber ducky next to you, who has presumably little knowledge of coding. This encourages you to explain in simple, logical steps why you did what you did or why you're choices were correct. This is similar to the idea of meta cognition, where you are examining your own train of thought. By examining your own actions in a slower and more concise fashion, you are more critical of yourself and it's easier to correct and adapt wrong behavior. Thinking of your next move in a strategy game can be done in probably less than a tenth of a second, as our minds work incredibly fast compared to the rest of our body. Speaking is degrees upon degrees slower, giving you more time to adjust and rethink important steps."
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7kq3h8 | When You Scream During a Rollercoaster Why Does The Fear Go Away? | Biology | explainlikeimfive | {
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"This is not necessarily so. While screaming can be a reaction to fear (or rather, to *surprise*), it is also a reaction to *excitement*. A roller coaster might not make you scream out of fear, but that adrenaline rush very well might. So, basically, the fear doesn't go away because you're screaming. You're screaming because the adrenaline is strong enough to make the fear go away.",
"I think Walt Whitman said it best, *I scream my barbaric YAWP over the rooftops of the world*. It's a release of energy, and any release drains the tension."
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7kq6by | Is blocking a punch effective if the arm used to block is in contact with my body? | Physics | explainlikeimfive | {
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"Your arms have much more muscle protecting your bones and do not house vital organs. Blocking a punch with your arms will distribute the force initially before it reaches your head. Knuckle-to-skull might as well be bone-to-bone. You may notice from boxing/UFC bouts that cuts do not occur to a fighters arms, but can easily be done to the head/face. The tension to break the skin is more common when the surface it comes in contact with is less malleable. And I know it's not related to physics as much, but in a combat setting, it makes more sense to be able to have your hands in-place to parry incoming strikes; often directed at the easiest place to render someone incapacitated (head)."
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7kqo5t | Why does glossolalia (i.e., tongues) occur in religious contexts? | Other | explainlikeimfive | {
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"text": [
"Pressure to conform cause some people to fake it. Other times, just believing something is real is enough to make our body act as if that thing is real. By telling people to expect pain from something that's not going to actually do anything to them, people will still often feel significant pain. So when you have people that are true believers in a religion, the illusion (or delusion) that spirits will speak through them or they will tap into some spiritual world and show that by speaking inspired speech is a strong enough illusion to make people feel like it's something happening to them through God, not just a thing they are doing on their own. The human brain is pretty nuts Edit: I don't know where it started precisely, but that's how it's perpetuated. The organization assigns value to this experience and that keeps it going. There is some biblical reference to it, and the idea is that they're speaking a divine language usually reserved for angels or whatever."
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7kqojo | How can nuclear fusion, which is the opposite of fission, also release so much energy in bombs? Shouldn't fusion require energy instead of releasing energy since it is building elements instead of breaking them down? | Physics | explainlikeimfive | {
"a_id": [
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"text": [
"They both produce energy up until a certain point, and that point is iron. Anything that is smaller than iron will produce energy through fusion, and anything larger will produce energy through fission. This is why when a star starts fusing iron in its core it dies shortly after.",
"Heavy elements release energy when they split because splitting up is a lower energy state. Light elements release energy when they combine because being combined is a lower energy state. Iron's right in the middle & happy to stay just where it is."
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7kqqxw | what happens to a candles wax when it burns and “disappears” I realize that smell molecules disperse into the air, and we smell them but what of the wax? What does it turn into and does it also disperse and leave a invisible residue? | Chemistry | explainlikeimfive | {
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"The wax turned to liquid \"near\" the flame, then turns to \"vapor\" once the temperature gets high enough. A chemical reaction takes place while the wax is in the vapor state. The result of the chemical reaction is heat (the flame), light (again, the flame), and the rest of the reaction turns to carbon monoxide, carbon dioxide, nitrogen, oxides of nitrogen, and water (with a few other minor chemicals). These are all gases that enter the space near the candle and disperse into the air. There is virtually no residue, except when you blow the candle out and some unburned hydrocarbons (black smoke) enter the air."
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7kqyk4 | Bayes' theorem. I understand the math behind it, but I don't understand how it works in a real life situation. | A disease test is 99% accurate when administered. This disease affects 0.5% of the population. According Bayes' theorem, if you test positive, you only have a 33% chance of actually having the disease. This means that even if you test positive on a test that is near perfect, but the disease is rare, you probably don't have disease. I get the math and the conclusion it makes. Basically, it stats the odds of getting the disease are a better indicator than the test when determining if someone has the disease or not. However, I still can't see how this works in real life. For example, in this situation, how can a test claim to be 99% accurate when it is wrong 67% of the time. Why administer the test at all if you know that the probability of the disease cannot mathematically be positive. Let's say the police do a DNA test to see if it is my blood at the crime scene. Well, since that DNA belongs to only one person of 7 billion, applying Bayes's theorum would only give a positivie result at a fraction of a fraction of percent. However, people get convicted for DNA matches all the time. Is this just a thought experiment, or is it applied in real life situations? I don't know, I am hoping some could give me a better general understanding. | Mathematics | explainlikeimfive | {
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"> For example, in this situation, how can a test claim to be 99% accurate when it is wrong 67% of the time. It's not wrong 67% of the time. It's wrong for *67% of people who get positive results.* It's right slightly more than 99% of the times it gives a negative result. The point of Bayes' theorem here is, *there are so many more people who don't have the disease that even with a very accurate test, false positives will outnumber true positives,* and that this issue can be quantified and managed."
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7krbfk | If we were to cover the ground with enough solar panels to generate all of our electricity, would atmosphere and ground not become substantially colder leading to new issues? | Physics | explainlikeimfive | {
"a_id": [
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"All the electricity we use in a year, in the world, is around 160 Terawatt-hours. This is slightly less than one hour's worth of sunlight in raw power, which is a bit over 170 TWh. Solar panels are around 20% efficient, so to generate all of the power we'd need *in a year*, we would need to use the equivalent of roughly 5 hours of sunlight hitting the earth. And, that power we capture in solar panels is almost all ultimately dissipated elsewhere on earth as heat. When you spin a motor or turn on a light, the motion and energy ultimately ends up as heat. So 1) the amount of power we use in a year is very small compared to the total amount of sun we get and 2) the energy doesn't just go away, it's simply converted into electricity for a short time, before it turns back into heat again. So in terms of the total heat energy we're getting, it's basically the same.",
"Not really. First, the best place to put such solar panels would be somewhere that you weren't using the land for other purposes. So you'd avoid building giant solar farms in agricultural lands and so forth. You'd put them on top of buildings, perhaps, or in deserts that get a lot of sun. And they might take some of the energy out of the sun but they certainly don't take all of it out. Second, the sun's energy is converted into electricity... and a big chunk of that is converted into heat when it's delivered and used somewhere. Solar panel generated electricity generates a little heat in an LED light bulb, but a lot of heat in a toaster or when applied to the heat exchanger in your fridge. So you have a minor reduction in ground temperature at a solar farm, but that's largely made up for a minor increase in temperature elsewhere. You might get some microclimate changes as wind patterns change a tiny bit, but unless you're talking creating some massive form of solar plant that wipes out a large forest, it's not going to substantially change the climate for a large region. However, if it somehow entirely replaces fossil fuel emissions, there could be big payoffs in terms of climate change reduction... and that in turn could avoid future tremendous changes in weather on coastal regions, for example."
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7krd3e | Why do liquids boil in a vacuum? | Physics | explainlikeimfive | {
"a_id": [
"drglg5c",
"drglpg4"
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"text": [
"In a vacuum, there is no pressure. This is critical for most liquids to remain in a liquid state because with no pressure, the temperature at which they start to boil drops",
"**TL;DR**: *Boiling - the process where a liquid energetically turns into gas - is very dependent on pressure.* Say you're standing at sea level. The pressure of the air around you and that is exerted on everything is roughly fourteen pounds for square inch. You can't feel it because it's entirely around you and constant, so your body has no way of registering it until you do something like stick your hand out of a moving car's window, and then you'll feel the increased pressure of the breeze on your skin. Now molecules. Molecules in water are always moving a bit, more at higher temperatures, less at lower. And they like to stay together until given enough energy to fly apart as they \"boil\". Each time a water molecule leaves a droplet, it takes a tiny bit of heat with it, which is why water droplets don't instantly boil away. Also, at room temperature, some molecules leave over time and cool the rest of the droplet in the process, which is why a drop of water somewhere will dry up even without ever reaching the \"boiling point\". When water molecules get to 212F/100C degrees at sea level, they start to super-rapidly escape the surface of the droplet because their energy is greater than the combination of that 14 pounds-per-square-inch pressure AND the other properties of water that keep it together. Water gas forms in the middle of the drop in addition to at its edges, and it rapidly completely boils away. So you get bursting bubbles of water vapour as it rapidly converts to a gas. Now climb a mountain, and as you go up it the air pressure declines. Heat your water... and because you're higher, there's less than 14 pounds per square inch squeezing that water. Now it's easier and takes less energy for the water to start boiling and fly away as gas, because it's being \"squeezed\" less. As you keep climbing out of the atmosphere, the air pressure that helps keep water squeezed together and remaining liquid reduces and reduces, until any temperature of water that's not solid ice will pretty much boil until it's a combination of frozen water that has had its heat stolen away, and water gas."
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7krd9j | Why do people tend to touch the wound immediately after injury? | Biology | explainlikeimfive | {
"a_id": [
"drglnfp"
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"text": [
"1) It's nice to know that whatever body part that got injured is still there in it's entirety, so we feel to check and assess the damage 2) To protect against a second strike in the same location. I mean, we defended it so poorly it got hit once, why not cover the weak spot in case round 2 immediately comes in?"
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7ksqx3 | Weight on the ground with magnets | URL_0 My question is: is the weight on "x" the same in both cases (+ magnets in the right) or is it A + magnet in the right, so that the magnets remove the weight from B Dont know why but my brain cant handle it | Physics | explainlikeimfive | {
"a_id": [
"drgubah"
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"No, in the second situation you have to add the weight of the magnets ;) As to the actual question, yes, the weights would be the same. The 'B' block pushes down on the first magnet; the first magnetic then exerts a force on the second magnet equal to the weight of the 'b' block and itself. The second magnet then pushes down down on 'a' with the force of itself, the first magnet, and block 'b'. As a result, the weight felt on the ground is the same (apart from the addition of the magnet's weights)."
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7kt7jh | Why didn't Europe start with the euro on a smaller scale first? | Economics | explainlikeimfive | {
"a_id": [
"drgxfph"
],
"text": [
"What do you mean “on a smaller scale”? Also, it’s not like they just switched it one day. In the years leading up to official Euro adoption, the different European countries worked to keep a fixed exchange rate between their currencies (having a fixed exchange rate is basically the same thing as sharing a currency). Countries joined this program one by one and at their own pace. It really was a gradual adoption"
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7kthhd | How does vinegar remove rainbow spots from stainless steel? | I know it works, but I'm wondering what are those rainbow spots on stainless steel kitchenware and how does a little bit of vinegar counter act it? | Chemistry | explainlikeimfive | {
"a_id": [
"drh1mvh"
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"Finally something my knowledge of metals will be useful for! The reason vinegar takes off rainbow spots on stainless is because the acid dissolves the very thin layer of heat oxidation. The oxide is formed when steel is subjected to high heat, which let's it oxidize, or rust, very repidly. Because vinegar is good at gently dissolving rust its also well suited to dissolve the heat oxide. On a technical note: The rainbow spots are actually the result of what's called the \"thin film effect\". Which is caused by the previously mentioned heat oxide layer. The layer of oxide refracts light at different wavelengths depending on its thickness. The thickness of the layer is dependant on the amount of heat the steel experiences. The colours range from a light straw colour to a deep rich blue and after the blue the colour turns to a dull grey. So if you have a hot spot on your stove and it heats a stainless pan the center will be darkest, fading out to no effect at all. Thus giving you the rainbow looking spots. As an aside this effect can happen to all steels, it's just easy to see on stainless."
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7ktmwe | How peeling scotch tape in a vacuum creates radiation. | Physics | explainlikeimfive | {
"a_id": [
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"drhxyjp",
"dri72ky"
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"text": [
"The phenomena is triboluminescence. It's not entirely understood by science, but what we think is happening is that when the tape is peeled, it creates charge (e.g. one surface keeps an electron when they're ripped apart). That charge quickly recombines, which--in air--ionizes the air and makes light. Absent of air, it seems the charge leaves as X-rays.",
"The adhesive in tape is an amorphous liquid and is mostly held together by covalent bonds. These bonds consist of electron pairs and together they are in equilibrium. When you break such a bond they will adjust to the new situation and lose the bond energy which is converted to light.",
"X-rays come from high voltage in a vacuum, where any flying atoms aren't stopped by air. Charged atoms and free electrons are always present, and they always speed up because of high voltage (because of electrical forces.) In air, this barely can happen, because flying particles are mixed in and become part of the air. (We can't create 10,000KPH wind. But it's easy to create 10KPH individual atoms.) When in a vacuum, single particles stay alone, and they don't create any wind when moving. Without the air-drag, they can speed up enormously. They can impact surfaces with extreme energy, and they spit out x-rays during those collisions. So, to make some penetrating radiation and x-ray photos, we just need some high-voltage well above roughly 15,000V (above 30KV is even better.) Rug-scuffing can't do this. We'd need a VandeGraaff or a Wimshurst generator, or a step-up transformer with an extreme voltage step-up ratio. (Back in 1910, hospitals were using Wimshurst generators to power their x-ray machines. VandeGraaffs and HV transformers came later.) So, a vacuum chamber always gives us an accidental, unexpected x-ray tube. Just apply some high enough voltage inside it. But with tape-peeling, where does the high voltage come from? This was discussed in a 1994 Science News article: [In the peel zone: Tape's electric gooeyness]( URL_0 ) *\"Peeling a strip of adhesive tape off a smooth surface is a violent process. As the adhesive stretches into strands, or fibrils, that suddenly snap apart, electrical activity is generated at the tape-surface juncture, often accompanied by a flickering glow visible in a darkened room.\"* Peeling tape creates opposite charges, with the adhesive charging with one polarity, and the tape-back getting the opposite polarity. (This is the \"tribo\" effect which is poorly understood.) When peeled, tape can generate some tiny sparks and create a couple thousand volts ...when in air. When in vacuum, the sparks are gone. The sparks were conductive, and were shorting out the opposite charges. With no air and no sparks, the opposite charges just keep growing higer. The tape's voltage rises over 10x higher when in vacuum. Rather than a slight blue glow, the tape gives off a slight glow made of high-energy EM emissions: x-rays. **tldr;** in vacuum, sparks are impossible. (Sparks are plasma, air-plasma.) Remove the sparks, and your tape-peeling creates 30,000V rather than just two or three thousand volts. For the non-five readers: they referenced this research paper: [1994 JT Dickinson Fracto-emission and electrical transients due to interfacial failure]( URL_1 )"
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"http://www.tandfonline.com/doi/abs/10.1163/156856194X00618"
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7kui2q | How is this not the answer to 1 divided by infinity? | Mathematics | explainlikeimfive | {
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"text": [
"> ELI5: How is this not the answer to 1 divided by infinity? In traditional mathematics, infinity isn't a number you can perform normal arithmetic operations with and 0.00...001 isn't an actual number."
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7kur9n | Why does time seem to freeze the moment you look at the second hand of a clock? | Biology | explainlikeimfive | {
"a_id": [
"drhbatm"
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"text": [
"It's a phenomenon called chronostasis. When you switch from looking from one place to another quickly, your brain fills in the space with the image that you settled on."
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7kv0in | How can someone get falsely convicted of a crime if you’re innocent until proven guilty (how can they prove you’re guilty)? | Other | explainlikeimfive | {
"a_id": [
"drhcgym",
"drhcia8"
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"text": [
"They could \"prove\" you are guilty using faked or incorrectly interpreted evidence. For example lie detectors are so inaccurate they are not considered admissible as evidence in most countries. You could also have an admission of guilt beaten out of you.",
"Because the measurement is 'beyond a reasonable doubt'. A group of 12 people can look at a thing and still make a mistake about it. Heck a group of 12 million people can look at a thing and still make a mistake about it. You can't really PROVE someone is guilty but you can show that they are probably guilty beyond a reasonable doubt (generally)."
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7kvqk0 | What does a human need in their daily diet to be healthy? | Biology | explainlikeimfive | {
"a_id": [
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"text": [
"Vitamins, minerals, protein and carbs in the correct proportions. These are the materials that our body is made of. You literally are what you eat. So, less junk food and more vegetables, fruits, nuts and seeds. Also drink more water."
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7kvtwy | How Tampons cause Toxic Shock Syndrome | For the life of me, I can't find any explanation on the internet on why the connection. Like how does a tampon cause an infection? | Biology | explainlikeimfive | {
"a_id": [
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"text": [
"It is not common. But if you put in a tampon and leave it there for days, or weeks you prevent the natural cleaning and immune system response of the vagina and trap the blood/bacteria in it causing an infection.",
"A few comments here have got most of the important pieces. Thought I’d add a few details because I think TSS is rad. Like people have been saying TSS is caused by bacteria. Specifically there are strains of staph and strep that are most frequently linked to TSS. These bacteria are able to produce “super antigens” that cause our body’s natural chemical signals to massively overreact (reaction is called a cytokine storm)This results in shock and can progress to organ failure. Again as others have pointed out the tampon is a perfect place for staph and strep to grow and produce their super-antigen. Wikipedia actually has a great overview of this process! It’s awesome.",
"I just wanted to add that you don't need to leave a tampon in for days to get TSS. It could just be in there a little too long. When tampon-linked TSS first came to public attention in the early '80s, it was due to an outbreak connected to the Rely brand of tampon. This was an ultra-absorbent tampon that women often wore for a longer period of time due to the extra absorbency. And then TSS numbers rose as a result. This is why they're vigilant about saying change tampons every 4-6 hours. And that you should use the tampon of the least absorbency that you need. So don't use ultra absorbency on a light day, for example. With TSS, you basically have a staph infection in your vagina. You don't realize it because it doesn't hurt when there and you can't see it, so it gets untreated and gets to a worse stage than it usually gets to if on a visible place that you can see and that hurts. If it's on your skin, say, they'll call it a staph infection, usually, even when it leads to toxic shock. It's a different name for the same phenomenon so it can seem like a different illness. It's not * always* staph, it can be a different bacteria, but staph is one of most common. It is also akin to flesh-eating bacteria. That causes toxic shock, too. In general, having a foreign body in you can present a fertile medium for bacteria to grow. If there are bacteria in your body, then your immune system can attack. But if the bacteria are on a foreign body that is in your body, like a tampon, bacteria may find that to be a fertile ground in which to grow, and your immune system doesn't have a good way to attack the bacteria there, as there's no blood circulation throughout the foreign body."
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7kvvo9 | Why do so many cars of different manufacturers look so similar? | Other | explainlikeimfive | {
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"Largely it's because all manufacturers are taking advantage of the same latest technology. Innovations in sheet-metal forming, or in making transmissions more compact, or in new headlight systems, are available to everyone within the same few years. Also because they are all responding to the same market forces and the same ever-changing government regulations. And finally, just fashion -- the same reason people in the 70s dressed one way and in the 80s another way.",
"There's a number of reasons: * **Multi-brand vehicles** - the same car sold under different brands with minor differences. A visually easy example to see are the [Citroen C1]( URL_4 ), [Toyota Aygo]( URL_0 ) and [Peugeot 107]( URL_5 ). Each car shares a huge number of part and features with each of the companies involved working in partnership to try launch a range of cars that were cheap and affordable for consumers. See [this]( URL_2 ) autocar article about it. * **Mimicking design** - high value and prestige brands like Mercedes, BMW etc. will often find that the lines and designs they have created are mimicked by less brands to create a luxurious appeal to their cars. In this case the car designs are deliberately trying to look like more expensive alternatives. An interesting example of this is the first generation of Mazda Mx-5 (Miura I think in the US?) which I am led to believe worked at getting the engine sound to be similar to an MG (a relatively traditional and reasonably well liked British car brand at the time). * **Legislation and efficiency** - there an enormous amount of regulation that impact how mass production cars can look - some of these are focussed on things like pedestrian safety, others on placement of light arrays, materials used. Efficiency has an impact as the lines and shapes are designed to balance maximising fuel efficiency with aerodynamics to get decent MPG. An example of some [EU legislation]( URL_1 ) on frontal protection systems (FPS): > 6.1.3. The height of the FPS, when fitted to a vehicle, shall be no more than 50 mm above the height of the bonnet leading edge reference line. * **Standing out is no always positive** - The re-sale value of pink car is lower than any other colour...for a reason. People will often choose more inherently conservative and 'normal' looking cars because they are at least in part considering the re-sale value of their car. The more unusual the design the more likely it is to only appeal to a segment of people, particularly for non-exotic cars. So whilst a regular saloon/sedan or hatchback car might have a few quirky features to tickle people's interesting bone, they will often be relatively conservatively designed so as not to stand out from the wider new-car mix. Big investments as a general rule are low-risk and cars being 'same-y' helps to reduce the risk of owning a car nobody wants in 3 years because the fad of the day has moved on EDIT: Forgot one of the biggest: * **Brand Design** - car companies want to create a brand image - so they use those features across all of their cars (e.g. the [Aston Martin grille]( URL_3 ) to build a consistent and coherent set of cars that all look related and part of the family. That can be inter-generational or just related to their current line-up. With companies like the VW Group this made even more pronounced when their VWs, Audi, Seat and Skoda brands all share a lot of the same design features and trends, making a large number of cars have common features.",
"Some brands are owned by the same manufacturer and are basically the same vehicle with brand-specific details... GM in the 80's & 90's was the worst with this, with only minor details like grill, taillights and seat stitching differentiating a Buick from an Oldsmobile from a Pontiac. You'll still see it today, with additional component differentiation, such as the Ford Escape and Lincoln MKC, where they are basically the same vehicle but the Lincoln gets upgraded components and luxury features. There are also vehicles build on a common architecture, so it's a little harder to see that they're related but underneath the sheet metal that is the case -- and because of that the size/proportions will be similar, such as the Hyundai Sonata and Kia Optima or VW Taureg and Porsche Cayanne. While most common with brands that are the same parent company, you may see collaborations across car makers, too (There were Chevy/Geo models that were co-developed with Toyota in the 90's). Or even car makers that simply buy and re-badge a model to fill out a line-up... say Chevy doesn't have a microcar but gas prices create sudden demand for tiny, fuel efficient cars. They may go to a carmaker who has something not sold in the U.S. and buy the rights to re-badge it and sell it, ie. the Chevrolet Aveo was made for them by Daewoo. And finally, there are certain size/price segments that are most popular with buyers and so car makers tend to cluster into certain size classes... so Honda, Toyota, and Nissan will all have compact, mid-size and larger sedans which roughly correspond in size/price. And Audi, Mercedes, BMW will do the same. And certain layouts that will work best to maximize space for the size, so you see lots of similar shapes based purely on the function of that layout/design."
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"http://eur-lex.europa.eu/legal-content/EN/TXT/?uri=CELEX:32009R0661",
"https://www.autocar.co.uk/car-news/new-cars/three-city-car-kind",
"https://www.google.co.uk/search?q=aston+martin+grill&source=lnms&tbm=isch&sa=X&ved=0ahUKEwiV6r_C_JbYAhUCBsAKHf5ICEAQ_AUICigB&biw=1240&bih=668",
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"https://en.wikipedia.org/wiki/Peugeot_107#/media/File:Peugeot_107_front_20071203.jpg"
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7kvzxz | What is the difference between forward and reverse osmosis? | I see "reverse osmosis water" on a lot of products these days and I'm curious how reverse osmosis is different. | Chemistry | explainlikeimfive | {
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"In osmosis, water travels through a membrane from a low-concentration (i.e. less dissolved solids) mixture to a high-concentration mixture until the concentration on both sides is the same. This happens spontaneously and can be quite dramatic if one side is extremely highly concentrated. This is why drinking salt water is so harmful, osmotic pressure starts sucking water out of your cells. *Reverse* osmosis is the inverse process, forcing water to cross from the concentrated side to the pure side. This *won't* happen naturally and requires high pressures, but also acts as a very effective filtration process because the membrane excludes most particulates and large ions.",
"I don't get how \"reverse osmosis\" is any different from \"filtration\"???",
"Just to confuse the issue - it is possible to purify water through forward osmosis as well and there are plants that do it. One typically draws the (pure) water into a another medium (say an amine) and free the water through another step - maybe distillation or reverse osmosis",
"When a liquid gets osmosisized, it literally goes through a liquid diffusion process. Think about it, when you put ice into a thermos, you get condensation right? The insulation in that thermos becomes exothermic, resulting in that condensation. Now put that same amount of ice into that same thermos while in a oven? You guessed it, reverse exothermic reaction. The volume of that melted ice will literally increase. Don't try this at home lol. With Deer Park and Aquafina (maybe Nestle water as well but not sure), they have gigantic reverse exothermic diffusion furnaces. Thousands of plastic bottles are grouped together and \" staged \" but only by 5 groups at a time, multiply that by hundreds of furnaces and that's how you get your delicious reverse osmosisized water. This process has been shown to be drastically cheaper than filtered mountain springs water. Which is pretty much why you can buy 25 bottles or so in a pack for only 3 bucks. It costs jobs unfortunately, but we'll save the politics for a different ELI5. Source: used to work as a lead operator in a Deere Park factory."
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7kw049 | How can MMA fighters often handle multiple blows to the face, but go down if they get a punch to the liver? | I have always wondered why this is the case. I’ve seen the most hardened fighters go down due to a simple kick or punch to the liver. Hope someone can explain this phenomenon to me. | Biology | explainlikeimfive | {
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"Your skull is really good at deflecting and absorbing impacts without actually taking anything beyond superficial damage. Getting hit in the face is painful and disorienting, but if the force isn't sufficient to actually cause a concussion or fracture there (usually) isn't actually much damage. The organs below the rib cage don't enjoy the same level of protection. Your brain, heart, and lungs are well defended by bone armor but the lower organs are exposed. Blows there can cause organ damage, forcefully empty the lungs, and/or fracture the \"floating\" ribs that aren't anchored to the sternum, all of which will drop even a skilled fighter if they take a bad body blow.",
"As I understand it, when the liver is struck, it causes blood vessels to dilate, resulting in a massive drop in blood pressure. This drop causes your brain to force your body into a prone position in order to still, you know, get blood.",
"Former hobby kickboxed here, getting punched in the head doesn't hurt at all because everything is well protected. There are several very important things in your torso that are not fully protected by the rib cage but are very sensitive to impact, cheif among which is the liver. It gets hit and your brain tells you that something very bad just happened (i.e. it hurts, alot). Your brain then stops you from continuing except in extraordinary circumstances where massive amounts of adrenaline allow you to get to safety. That's how my instructor explained it anyway",
"Taking a blow to the liver is no joke, I fell off my bike when I was like 12. I wasn't even going fast, walking pace at the most, an imperfection on the road caught the front tire, twisted the handlebars in a way that it stopped the bike dead on its tracks, almost went over the handlebars but I did not have enough speed to clear it, I landed on the now facing up handle bruising my liver. I had to go to the ER to make sure I didn't rupture anything because it was hurting so bad, after a few test and ultrasounds, nothing major just a bruised liver, that lasted a day or two."
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7kwaqg | If smells are tiny bits of matter, how is it that static electricity, being energy, has a scent? | Chemistry | explainlikeimfive | {
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"text": [
"You're smelling ozone. In the presence of an electrical discharge (more noticeable after a lightning strike) O-3 forms, which is what you're smelling."
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7kwb5d | How do they "feed" artifical organs(such as skin)? | Like say scientists are growing a piece of skin from a group of "seed" cells. How/what do they feed the skin so that it doesn't die? | Biology | explainlikeimfive | {
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"Hi! This is related to my research project right now so I'm glad I can answer We are feeding the cells themselves, not the tissue as one unit. We do this by effectively letting cells sit in a solution of nutrients and proteins that the cells need to take in to function when normally inside a body (plus some other things because they are living outside, such as antibiotics) So this is a solution of ions, proteins, vitamins, etc, that have been specifically designed to mimic the conditions of the host skin, to make the cells think that they are in a skin-producing environment",
"Nutrient broth (contains carbohydrate, amino acids (protein), fatty acids (fat), salts etc), bovine serum (calf blood, with all the cells removed, has lots of growth factors etc that the cells need) and antibiotics to prevent infection. The media contains indicators to tell us when the pH changes and needs replacing. The cells essentially sit in a bath of it and take the media through their cell walls."
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7kwhos | Why do finger nails grow faster than toe nails? | Biology | explainlikeimfive | {
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"*We aren't sure.* Here are two good theories: 1. Blood circulation is better in the fingers, feeding nail growth. Compare this to your feet, which are given the short stick in regards to blood supply in the body. 2. \"Terminal trauma\" -- meaning the more you use a digit, the more your body assumes it needs to grow, because the nail is being worn down quickly.",
"In the animalistic sense, you would use your hands more than your feet for digging and fighting, thus your nails on your hands would get more use and need to grow faster for survival purposes. They are like really lame claws. They're practically vestigial now.",
"I thought I read somewhere that the rate of growth of the nail is directly related to the size of the phalange. Fingers have longer bones than toes, hence they grow faster.",
"One possible factor is that frequent friction inside shoes puts more wear on toenails resulting in less frequent need for trimming.",
"Studies have found that your fingers absorb more calcium than your toes. This leads to nail growth.",
"Your fingers are much more sensitive and are constantly touching things which stimulates faster growth compared to your toes which just kinda sit in your shoes all day and don't really get much situation and reason to grow. Also because your fingers are touching more things, they may wear down faster so it was needed to grow back faster.",
"Followup question: Why do my ring finger nails grow faster than the other fingers?",
"Vitamin D is a contributor to nail growth and strength. Your body produces more vitamin D with more sunlight. Just a theory, but maybe since your hands spend less time covered like your toes and are exposed to sunlight more often, might be a reason? Or just because one are covered and the others arent means nothing if your body produces vitamin D and distributes evenly....so who knows",
"From an evolutionary standpoint, nails, or claws on a creature's forelimbs are more commonly used for digging, as weapons, or other tools, in addition to traction, while rear limb claws/nails would only be regularly used for traction. Thus they would wear faster, and need to grow faster. From personal experience, I know that my cat's claws grow this way. That human nails exhibit this same growth behavior is likely an 'evolutionary holdover', though I'm sure it's still been a useful trait for a significant part of human history.",
"Your nails grow in proportion to the length of the digit to which they are attached (i.e., the nail on your middle finger grows faster than the nail on your thumb which in turn grows faster than the nail on your pinky toe). As for the exact reason why that is the case I'm not sure we know the answer."
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7kwiot | What happens in a bipolar person's brain causes them to go "manic" or "depressed"?? | Biology | explainlikeimfive | {
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"I'm bipolar 2, and no doctor has ever given me the same answer as another doctor. It's one of those things where they don't know the direct cause, but they know how to treat it (success widely varies due to so many factors). Most doctors think it's a combination of genetics and past experiences which cause bipolar (nature loaded the gun, nurture pulled the trigger). The phases of bipolar are caused... basically by everything. When I enter a mixed state or a depressed state, it's an overreaction of my body to some sort of stimulus. In my case, it's by far a social stimulus as when I send a lot of time alone (and not focused on the past), I'm usually ok.",
"Ahoy, matey! These posts may shed a bit of light, though I think there's room for better answers still. 1. [ELI5: Bipolar Disorder ]( URL_1 ) ^(_24 comments_) 1. [ELI5: Someone who is bipolar/manic-depressive, what does it FEEL like, both on and off meds? And how can I help? ]( URL_0 ) ^(_9 comments_)",
"I read a paper recently that asserts, among other things, that a dysfunctional secondary signaling system allows for runaway upregulation or downregulation of certain receptor site. Also, many have hypothesized that a discordant circadian cycle can initiate the swings, but it is still a pretty murky subject.",
"Hi, person with bipolar here. I understand it to be a chemical imbalance in the brain. The meds keep you in the normal range so you do not go back and forth between the two extremes, which are unhealthy.",
"Bipolar here as well. I think it may even be the case that they are not even sure of the exact mechanism of action on some atypical antipsychotics (which stop you from going manic). I'm on [Latuda]( URL_0 ). Not the most ELI5 article, but it does explain presumably how it stops you from going manic. Although, I don't hold out much hope for this thread, since most of reddit seems to think that mental illnesses don't affect your daily life. If you say you have problems with your life due to mental illness, then you're just making excuses—according to reddit. The ELI5 explanation you're most likely to receive: nothing happens—they are just failures blaming their instability on \"mental illness\".",
"Physical, chemical or emotional stress. Being in a fight or flight state for too long could be the reason. Try to succeed at the basics of health to achieve a balance in the body. Exercising enough is important, like going for long walks or jogging for 20 minutes. Nutrition is very important aswell (people with mental problems might have nutritional defficiency's). Try to eat 7 to 10 cups of vegetables a day, especially dark green vegetables like broccoli and spinach (magnesium and potassium are important minerals). If you can, try to eat fish a couple of times a week to feed the brain. Sleep is important so try to do your best to get atleast 6 hours of decent rest a day. Avoid emotional stress if you can, but if it's necessary to achieve something you can't always avoid it. Greets",
"Reading these comments are making me think I need to see a doctor. For years I have had problems where when I’m sick or tired I get really wound up, while stress or sudden changes make me incredibly depressed."
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7kwist | when filling an empty bottle with running water, why does it sound low-pitched at first, and slowly grow higher-pitched? | Physics | explainlikeimfive | {
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"Sound is created by vibrations in air. The amount of air in the bottle determines the \"size\" of those vibrations which in turn determines their pitch. Larger vibrations correspond to lower tone sounds and smaller vibrations correspond to higher pitch sounds. As you fill up the bottle with water, the empty space in the bottle gets smaller and smaller, reducing the size of the vibrations in air."
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7kx8kg | What did Farm animals do before they were maintained by farmers? | For example how did sheep keep their wool short or how did Horses keep their hooves short before Farmers thought to keep them and maintain them? For example even today there was a famous example of a sheep getting lost in the mountains when it was discovered it could barely walk due to the amount of excessive wool it grew. So how would sheep and other farm animals counter this and similar issues before they were domesticated? | Biology | explainlikeimfive | {
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"They did not exist. Our current farm animals were bred from much hardier wild animals, by humans using selective breeding.",
"> For example how did sheep keep their wool short Sheep didn't have long coats until humans bred them to have long coats. Farming is what *created* the long coats. > how did Horses keep their hooves short before Farmers thought to keep them and maintain them? Horses' hooves naturally get worn down by walking. They don't really need to be maintained unless they never have access to rough terrain, or we want to affix horseshoes to protect their hooves on rocks/pavement",
"Howdy. I have sheep. Sheep originally did not have wool.. well not like todays sheep. Some sheep today still don't have wool and are called \"Hair sheep\" they shed just like dogs.. imagine a German Shepherd dog.. that's about the same as a hair sheep (google Barbadoes Sheep, or Katahdin.. or hair sheep). But SOME of those sheep did get thicker coats in the winter with a few wool like hairs that didn't shed as easily. Farmers started breeding some sheep selecting for that, until they produced sheep with wool that don't shed on their own. Just like how wolves shed, but poodles don't! Horses are another matter... the ground they would be on was harder than in a pasture so they chip their hooves and pieces fall off. HOWEVER most certainly this didn't always happen and horses that lived in areas where their feed didn't wear down as easily would die of starvation if they had a hard time walking to different places for food - but i note horses tend to walk and eat and walk and eat at the same time.."
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7kxqd1 | Why does a fever feel so terrible? | Biology | explainlikeimfive | {
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"Some of the compounds released by your body in the inflammation pathway (which is involved in creating a fever) are also involved in pain pathways, so they cause pain and discomfort as well."
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7kybwd | why do sugary liquids make you even more thirsty? | Biology | explainlikeimfive | {
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"If your blood sugar gets too high, your body will try to get rid of the extra sugar by flushing it out with water. Your body will take water out of you body, put it in your blood, then dump the extra sugery blood through your kidneys to try to restore a good sugar level. With all of this water getting moved around and out of your body... you get thirsty. It is your body replacing the water it used to clean out your systen."
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7kygvd | What causes the lightheaded & tingly sensations after standing up too fast? | Biology | explainlikeimfive | {
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"Blood is pulled down by gravity. When you suddenly stand up, your heart doesn't have time to realize what's going on and pump faster, so less blood reaches your brain. This makes you feel lightheaded. Then after a moment, the muscles in your arteries squeeze together making the tubes shooting the blood up narrower. This allows the heart to send more blood up to your brain, which makes the lightheaded sensation go away. To put it another way, take a garden hose and make it horizontal. See how far the water goes. Then point it straight up. The water doesn't go very far up because of gravity. Then cover the hose with your thumb to make the hole narrower. The water shoots up much father."
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7kyyxv | I read that as fat is gained, lots of blood vessels are generated. Can someone explain this in more detail and what happens to these blood vessels as fat is lost? | Biology | explainlikeimfive | {
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"The process is called angiogenesis. Basically as more adipose tissue is accumulated, small vasculature will be generate to supply it with oxygen like and other cellular tissue. But often the accumulation of fat out matches the rate of angiogenesis cause tissue to not get proper oxygen supply causing hypoxia and feel death. This cellular death and damage is one of the reasons obesity or directly correlated to increased risk of some forms of cancer developing. Due to increased cellular damage and mutation. As to where the gained vasculature goes when fat is lost? I am not completely sure. Good question! But I would assume the material would be recycled and repurposed or excreted.",
"The former part of your question is answered by u/iammuchburrito, so I'll just talk about the latter. Nothing happens to the blood vessels, because the fat isn't \"lost\" the way it sounds like it is. When the body taps fat reserves for energy, it doesn't kill and eat the cells. Rather, it accesses their internal reserves, and they shrink. This has obvious metabolic benefits - it's more expensive to create a new cell than to \"refill\" an existing one, so reuse of fat cells makes sense. However, it has equally obvious disadvantages in an environment where caloric excess is more common than caloric restriction. Once you've gained weight (therefore adding fat cells), it is difficult to lose it; the cells don't go away. And once the cells exist, it is easy to \"refill\" them, so weight goes back on very quickly. And since all the fat tissue has blood vessels - they're living cells, of course, so they require blood supply just like all other living tissue in your body does - it is difficult to mechanically remove it. Any attempt to \"suck\" fat out has to consider the amount of internal bleeding which will result from shredding living tissue."
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7kz5iv | when the cable company says they will send a signal to your tv/modem, how does that works? | Technology | explainlikeimfive | {
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"The same way anything else gets to your modem/TV. Every device attached to their system has an address, just like your home address. They can just punch in that address and BLEEP BLOOP the info gets sent right to your device. The same way an email knows to go from my account to your account or a text knows to go from my phone to your phone.",
"With a cable network, everybody in the area receives everything, all of the time. Right now, your cable box is receiving all of the channels, even if you haven't paid for them - what it's not doing is allowing you to tune into them. When they send a signal (called a 'hit' in UK cable parlance, I'm not sure what other countries call it) that goes out to everyone in the area, and all the boxes and modems receive it - however, because that hit starts off with a bit of information that says \"I am for /u/xxgoozxx's modem, and that modem only\", all of the others will ignore it."
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7kz8xa | When a woman is carrying more than one baby doctors refer to them as A, B, C and D. Are they able to tell which baby is which after delivery? If so, how? | Biology | explainlikeimfive | {
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"The official designation is based on the order delivered. That may be the same or different than what they're identified as on ultrasound. The designations during the ultrasounds are only for that particular instance and it's not at all unusual for the same fetus to be referred to as different letters from one visit to the next unless there are identifying characteristics and they choose to keep them the same. For instance, fetus A is generally the presenting fetus--that is, the one first entering the birth canal. It entirely possible for that to change over the course of a pregnancy. But even if it doesn't, if the same baby has been presenting (and you can prove it because it's a boy and the other is a girl) the entire pregnancy, but they have to do a C-section and fetus B is in front while fetus A is behind... Fetus B just became Baby A."
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7kz9rl | How can "analysis of competing hypotheses" guide decision making? | Other | explainlikeimfive | {
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"The key advantage of ACH is that it maximizes the chance that you avoid false conclusions. It does this by forcing you to take the evidence you have and see what it negates, rather than what it supports. Imagine, for example, that there is a murder and two possible people that might have committed it. There might be 1,000 pieces of evidence relating to motive or opportunity that point to one of the two suspects. Maybe Suspect A hated the victim, and owned a gun of the same kind that was used in the killing, and stood to make money if the victim perished when he did. Maybe suspect B was seen in the vicinity of the crime scene, and had threatened the victim in the past, and also stood to make money after the suspect's death. Based on that, you could probably come up with strong arguments that either one committed the crime, but in reality, none of that evidence is really conclusive. What would be conclusive, though, might be evidence that Suspect A wasn't in town the day of the murder. That's not because it adds anything to the case against suspect B, but rather because it tells you that Suspect A could not have committed the crime. Focusing on disproving hypotheses -- something that the right evidence can do fairly reliably -- rather than on the nearly impossible task of proving a hypothesis, ends up leading to better decisions."
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7kzd01 | What is that newborn baby smell and how does it stay for weeks? | Biology | explainlikeimfive | {
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"You mean the one from the head? Those are pheromones released by the baby to make people love them. It's almost intoxicating, and even stronger if the baby is yours. And yes, humans are subject to the effects of pheromones."
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7kzssu | Conservation of energy during destructive interference | Physics | explainlikeimfive | {
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"text": [
"You must have points where the inteference is constructive aswell. You can think of interference as a redistribution of energy: at some plsces there'll be more than before, at some places there'll be less. The energy does not disappear."
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7l0dp4 | ; what is a social worker and what kind of jobs do they do | Other | explainlikeimfive | {
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"text": [
"Social work is basically a helping profession. Social workers help create linkages to people who need welfare services. They also help in organizing communities. A social worker usually works in the government, NGOs, clinics, and other agencies that help other people.",
"My mother was a social worker in a hospital. She helped the families when they needed help. Was kind of a resource directory for them to get help...ie rehab, public aid, AA, battered woman, etc. During her life also came along the psych wards of today. These include drug addicts, and the mentally unstable. She would help them in group therapy, and also assist families for out patient/home care."
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7l0g2e | Why does it seem like our body heals, grows and changes overall more while sleeping? | Biology | explainlikeimfive | {
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"text": [
"NREM sleep triggers different kinds of growth hormones. [This article]( URL_0 ) gives an interesting example where children who do not get enough oxygen during their sleep get a growth defect which is fixed when their oversized tonsils are removed. That way the body can get enough oxygen to accommodate the growth process and it starts growing again. Another reason might be that you're not looking at your wounds/hair/nails etc. for a couple of hours while you sleep, so there is a gap in your perception there, whereas you can watch the whole proces while you're awake."
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7l17w9 | How is only one photon/particle able to form an interference pattern in the double slit experiment? | Physics | explainlikeimfive | {
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"text": [
"This experiment is used to show the simultaneous double behaviour of photons: They not only act as particles, but also as waves. Because of that, they will act like waves passing trhough little slits, leading to interference patterns, like you can see here: URL_0",
"The [Copenhagen interpretation]( URL_0 ) loosely states that the particle can thought of as a wave of probabilities, probabilities that the particle exists in specific spot. So essentially when you’re not measuring the photon, it doesn’t quite exist. When you do measure it and try to determine its location, the photon collapses into a particle. So per the double slit experiment, your photon wave function (probability cloud) is what interferes with itself. Since the photon doesn’t really exist as a single particle before you measure it, you say it has a superposition of many states (a wave function). Ultimately this is the reasoning behind the Schrödinger’s cat thought experiment. The cat exists as a superstate of alive and dead at the same time, until you look inside and it “collapses” into a single state."
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7l1v83 | Why does a house lose value if a crime occurred in it? | Other | explainlikeimfive | {
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"text": [
"It’s basic supply and demand... Let’s say there are 100 potential buyers for a house at a certain price. But let’s say 20 are weirded out by a murder in the house and won’t consider it as a result. Now, while the other houses at a price have 100 potential buyers, this particular house only has 80.",
"If a crime was committed in a house, it is likely that crimes happen in other houses nearby, and overall suggests a more dangerous neighborhood."
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7l21zr | In court, how can they determine whether or not evidence is real or fake? | Other | explainlikeimfive | {
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"text": [
"If there's doubt about the source history of evidence, the defense will definitely bring it up. Was a video file obtained by police directly from a security camera system, or is the source more dubious? Is physical evidence collected from the crime scene immediately and held in police custody, or did it turn up later or get \"lost\" at some point? Numerous cases have been thrown out over the years because evidence was mishandled, forged, or unverifiable. Many people have been convicted of evidence tampering as a result. In the US, guilt must be proven \"beyond a reasonable doubt.\" If the history of the evidence presented isn't rock solid, that's a high bar to clear.",
"There are expert witnesses that can be brought in to verify or debunk evidence by the prosecution or defense if they think they need to do so to win the case. In theory, this should stop most fake evidence. In reality, even if we assume that we have enough expert witnesses to go over every piece of evidence that could feasibly be faked, and they had a 100% success rate at identifying fakes using known verification methods... that only catches the types of faking they know about. If they are not aware of a method for faking something, fake evidence can get by an expert. In super-harsh reality: most evidence is assumed to be valid unless someone involved in the process feels like there's a good chance that something is fake. I don't have any statistics about this off-hand, but I would be *very* surprised if there were no convictions of innocent people that were based on falsified evidence."
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7l2eyv | when you squish a bug, why does yellowish goo come out instead of organs and red blood? | Biology | explainlikeimfive | {
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"text": [
"Some insects don't use the same oxygen transport molecule (hemoglobin) that humans do, instead preferring other molecules that are yellow, green, or blue in color. When you kill them, the blood is greenish. Many species do have red blood though, they're not all the same. Organs are tiny and well secured to the inside wall of the exoskeleton so they're unlikely to come out in any discernible way. Insects don't have veins and arteries but rather are basically filled with that viscous \"blood\", so you typically see that when you crack the exoskeleton open."
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7l2o2m | How exactly does extreme pressure create heat/friction? | For example in a star. The intense crush of the stars gravity creates heat to a point where fusion begins. What is actually happening to the atoms under this enormous pressure? | Physics | explainlikeimfive | {
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"text": [
"For most gases, the general rule of thumb that follows is that in a constant volume, if you increase the pressure, you will also increase the temperature. This is due to forcing the particles to be closer together, increasing their chances to encounter and in turn increasing their kinetic energy. When it comes to the sun, we are talking immense amounts of pressure, under which the temperatures reach star level temps.",
"This is an ELI5 answer, so some details are left out and there are lots of simplifications. At the atomic level, pressure is atoms smacking into other atoms at speed, and bouncing off. Think of the Pressure as the sum of all the forces causing all the rebounds over an area divided by the area. Temperature is proportional to the velocity squared of the atoms as they move around so if you double the average speed, you quadruple the temperature. At the atomic level, the notion of friction really doesn't exist, that's really a macro concept that is usually due to many macro phenomena (high points of one surface cutting grooves in other surfaces, adhesive forces, elastic deformation, etc. Actually friction is a tremendously complicated subject, but that's OT) which don't really apply to individual atoms. At the atomic level there are only 4 forces (gravitational, electromagnetic, strong nuclear and weak nuclear), and the rebounds are caused by the electromagnetic force. So take a bunch of slow moving atoms spread over space, attracted to each other due to their combined mass and gravity, think of them falling downhill to each other, picking up speed. As they go from a wide area to a much smaller area, they go faster and faster, and there are a lot more of them in a tiny area, so they whack each other harder, hence pressure goes up, and move faster hence temperature goes up. Eventually they get moving so fast, that the nucleus of the atoms bang into each other, much like a car wreck, and fuse their nucleus into bigger atoms. When this happens, it is called fusion, and if the atoms have small nuclei, like Hydrogen, it gives up more energy, which makes all the atoms around them move even faster, which leads to more fusions, and so on. As you might imagine, it takes enormous speed, and huge collision forces to get atoms to actually fuse, because their inclination is to repel each other. For all this to happen you need a truly enormous amount of particles. For instance, the Sun is as massive as 333,000 earths, so they have a whole mess of particles. In fact the Sun has been converting Hydrogen to Helium at a rate of around 600 Million tons of Hydrogen per second for billions of years now."
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7l339p | Why does blood not stick to human skin like a permanent marker, but will stain things like clothes so bad? | I noticed that blood comes off of skin very easily, but a marker won’t, and vice versa, marker comes off some products, but blood won’t. What’s the deal? | Biology | explainlikeimfive | {
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"Skin: Your skin is fairly smooth, and is waterproof. When you draw on your arm in marker, the ink is carried from the tip to your skin by a solvent, like propyl alcohol, this solvent quickly dries. The solvent isn't water, so it penetrates more deeply into the keratinized layer of skin. This leaves the ink on the top of your skin, and a little will get INSIDE your skin (I'm talking in microns) this is why when you wash it off, most of it, the stuff on the surface, comes off fairly easily. It isn't water soluble, so you have to scrub and use soap, but it comes off. Then you always have a little left, the stuff INSIDE the very outside layer. Which you have to scrub hard to get off, you're mostly just scrubbing off that layer. For blood, it can't get inside your skin, so it just dries on the surface. It's also water soluble, so it's easier to get off. The color is also from red blood cells, they're much larger than ink molecules, but the blood just stays in the cracks of your skin that are harder to clean. Fabric: Think of a rope, the brown kind you see on ships in movies. Thread isn't that much different, just smaller. Ink will stain the fabric just easily as blood. The solvent spreads the ink into the fabric through capillary action and that's why when you draw on a white shirt with marker, you get the bleed where you aren't marking, the ink is traveling down the thread. Blood interacts with the threads in a similar way. Cotton will absorb water, so blood will absorb onto the thread just like ink. It will go into all the little nooks and crannies of the thread, and while red blood cells are bigger than the ink, they're small enough to get to the very inside of the thread. Then you try to wash the blood out, the red blood cells are inside that thread, they're trapped now, they flow in, but can't flow out. When you wash it, the red blood cells pop, leaving the red color behind, which is still trapped, stuck to individual cotton fibers now. That's why you can wash out *some* of the blood, it's the blood on the surface of the thread, but you can't wash the blood that's on the inside of the thread. Edit: I avoided talking about prune fingers because it's contentious and irrelevant to this ELI5. Prune fingers are better at grabbing while underwater, but is it due to the absorption of a small amount of water on the exterior surface of your skin? Or is it due to the body increasing the porosity of the capillaries at the skin on your fingers that causes the swelling? It's currently being investigated and I have yet to see conclusive results from either side. However, it's irrelevant for this conversation. If you put your hand in a bowl of water, how long does it take to get prune fingers? How often are you floating your hand in blood? If I put a droplet of blood on your arm, it will bead up and you can just brush it off. Or, you can take a cloth, and the cloth will absorb the blood. So for this conversation, skin is waterproof. Edit 2: a couple people have mentioned that those with nerve damage don't get prune fingers, which supports skin being waterproof and that prune fingers are from a biological response. I haven't heard of this before, so I won't comment on it beyond saying that it's compelling proof. That prune fingers is due to absorption of water by the skin was probably not something a scientist tested. It is a completely logical and sound thing for someone to assume, and even if skin is waterproof, that you *eventually* absorb *some* water is still reasonable. These kinds of facts are very common, no one thinks to test them, there really isn't any reason to, until there is. That prune fingers is due to a biological response could be a very important fact for science, it can help teach us about localized responses, how local conditions are sensed, how the brain analyzes the information, and many other things. This is why I question everything, if it hasn't been tested, then it is only a hypothesis, not a fact. Also, not to trust anyone, always read the literature XDl Edit 3: jeebus I gots gold.",
"It's not about the blood, it's about the material the blood is getting on. Clothes are very prone to stain in general due to the fabrics involved. The fabric will absorb the blood the same way it absorbs water, soda, wine, etc. You skin isn't absorbent like that.",
"Have you tried cleaning larger amounts of dry blood from human skin? It requires a lot of rubbing and some cleaning agent, I wouldn't call it \"very easy\". Liquid blood is quite effortless to remove though. Source: am a medical professional.",
"materials like fabric have many pores and crevices that the blood can get into. when the blood coagulates, it undergoes a chemical change that hardens it in place. once tangled with many fibers and ...'cured', it's nearly impossible to get out. this is because, kinda like glue, your blood is designed to 'freeze' in place to physically block cuts in your skin when it is damaged. Now consider your skin, it is a wall to protect you from the outside down to the cellular level. It even has some complex self-cleaning mechanisms in the pores. Outside of hair and pores, blood doesnt really have much to grab onto. but, alas, your skin isnt perfect. once blood is dried on, it'll find any little cracks and folds and stick in them, requiring some scrubbing. Source: I've modeled the reactions involved in coagulating blood for my job.",
"Blood comes off of clothes if washed with cold water. Hot water actually makes the blood stains permanent. It's a matter of what is being used to remove the stain. To remove a permanent marker stain, alcohol, being a favorable solvent, is a good alternative. Same way (cold) water for blood. What happens with hot water is that the biomolecules inside blood do get dissociated into simpler components which are not very affine(soluble) with water.",
"There's a lot of reasons, but the basic answer is porosity. Imagine clothing or fabric as a sponge--lots of little holes for stuff to fill. Blood soaks into it easily. If the clothing is a sponge, your skn is closer to wood. Still porous, can still absorb things, but not nearly as easily as a sponge. Permanent markers, on the other hand, have ink particles that are much smaller than red blood cells--therefore, they can squeeze through smaller holes. In our wood vs sponge analogy, the permanent marker will have an easier time sticking to wood than the blood did. It also uses alcohol as a solvent which dries more rapidly than water, and so you also get the ink drying on the surface. Leaving blood on your skin long enough for it to dry will do the same thing. As for why blood sticks better to some things despite this, it's because blood also has a clotting mechanism that ink particles in a sharpie don't. After drying, the blood may clot up and stick to a surface more firmly, where the ink particles are less sticky. That's why if you've got a dry bloodstain on a white shirt, draw with a sharpie on it, and wash it over and over the sharpie should fade faster than the bloodstain--the blood sticks better, and is harder to remove. It's just harder to soak in in the first place",
"I'd imagine it's due in part because blood is mostly water, while markers tend to be mostly some kind of chemical, depending on which. Most are solvents, I believe. Water soaks nicely into absorbant material and proteins, like blood plasma, don't come out all that well. Our skin doesn't absorb water that well. Markers dye the upper layer of the skin, as solvents like alcohols have an easier time getting in, so it takes until it's shed to go away, unless you use something like acetone to actively remove it. Fabrics also happily absorb solvents, and get dyed by the color that comes with it. I'm sure someone more knowledgeable will have a better answer though and I am eagerly awaiting to learn.",
"Blood contains a complex molecule called heme, which contains iron that gives it the red color. Heme is what carries oxygen in your blood. In most fabrics, the blood cells can get in between the individual fibers. When washed in hot water, the heme breaks down and reacts with the fabric, becoming chemically bound to it and creating a stain. Always wash blood in cold water because it doesn’t react very much at low temperature. On skin, there’s nothing for the blood to get “between”, and when the cells break, nothing for the heme to bind to. Therefore, relatively easy to wash off.",
"Blood cannot stain your skin because it cannot penetrate the outer layers of it. Water cannot penetrate cellular membranes and as you may know, blood is mostly water. However liposoluble substances can, among others. The dead keracytes that compose the outer layers are what make the skin waterproof. Most fabrics like cotton and polyester are permeable. Blood can therefore penetrate the fibers and stain it much more profoundly. Also nurse trick to remove blood, use hydrogen peroxyde quickly and rub. The blood stain will go away easily.",
"Blood = Water + Sodium Chloride (and some other stuff) Skin = A layer of dead flakes spread out over an elastic surface (containing micro organisms which don't like invaders), covered in oil. Water + Oil don't mix. Top layer of skin designed to flake off when disturbed. Bacteria cover surface who are in the habit of eating things that get too close. Massive theocratic military who believe it is their duty to die for 'greater good' living beneath the surface of your skin waiting to descend on anything trying to get in with psychopathic zeal. Clothes however- clothes are just asking for it.."
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7l352a | How does the US dollar come back to the US when it has been used in other countries? | Economics | explainlikeimfive | {
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"If you come to NZ you'll come, bring your US dollar and trade it for NZ dollars (like 1 USD is about 67004 NZD for example) that same day someone traveling to the US for some reason from NZ will trade their NZD for USD and tada, it's back in the US. Money rarely stays put, it's always circulating. Exchanges, either at banks or through exchange companies, ensure that foreign currency stays circulating.",
"Americans buy TVs from China. They get a TV and give dollars to a TV seller. The Chinese company that made the TV takes those dollars and converts them back into the local Chinese yuan in order to pay their workers, their suppliers, etc. The People's Bank of China now has a bunch of extra dollars. They take those dollars and buy US Treasury Bonds. The US federal government's budget deficit is one of the mechanisms by which foreign dollars are repatriated to the US. If the US runs a trade deficit (more imports than exports) we must be running an investment surplus (more investment than savings)."
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7l3749 | How does an explosion cause death? | Other | explainlikeimfive | {
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"From the outside, pressure waves and flying debris crush the organs and cause other damage, causing death. From the inside, pressure waves push organs and tissues out of place at a high rate of speed, never mind the shrapnel from whatever exploded. The sudden, traumatic loss of blood pressure and vital tissues results in death.",
"Lots of ways. Two big ones: The rapid compression/decompression from a shock wave can rupture internal organs. Your insides get shaken apart. You can be thrown by the shockwave, and receive other trauma. You smack into something real hard or get impaled by some object.",
"An explosion has two forces. One is the shrapnel and other materials the explosion throws outwards. This tears up the body, destroy organs, etc. The second is the rapid expansion of gases that the explosives create. Think of an explosion as a really fast fire. That creates a shockwave that moves out across the air. As the shockwave crosses the body, it rapidly compresses the air pockets in the body such as sinuses, lungs, ear drums, damaging them and other internal organs. Strong enough shockwave can also damage the nerves in the eyes and brain.",
"Just an adition to the shockwave point... If the explosion is faster the speed of sound, The shockwave will behave like, in your body's perspective anyway, basically a hard wall. Assuming that the body doesn't hit another thing after being knocked off by the shockwave, you'd die the same way as you would from falling off a really high building. Of course in practice, you'd hit many other things too...",
"I'm assuming you mean aside from whatever shrapnel or debris might be flying into one's body. The impact of the shock wave on the body can be jarring enough to stop the heart or cause other life threatening internal damage."
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7l3gzb | What happens to our cells when we die? | So our bodies are made of living cells, but when we die, do all of the cells die? Are dead bodies a clump of dead cells? Or do the cells die off and leave what’s left which isn’t cells? This may seem like an elementary question but I just don’t understand. | Biology | explainlikeimfive | {
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"Your cells don't all die at once, they continue kicking individually until they've exhausted all the nutrients and oxygen they've stored. For high-power nerve cells this happens in just a few minutes, they have minimal storage and a high burn rate. Low resting rate cells with vast energy reserves like muscle tissue can linger for much longer, and are still metabolically active for some time after death. Lower temperatures slow down cell metabolism and keep them alive longer."
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7l3z77 | How do you reverse engineer the ingredients of a chemical formula? | Chemistry | explainlikeimfive | {
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"Well, you can use a gas chromatograph to measure the different elements and ions in the mystery substance. That's not totally enough information, so then you'd have to look at how those \"lego blocks\" might be arranged in a stable molecule. Sometimes there are a couple of possibilities. When you get it down to a list of possibilities you can define specific tests to measure A vs B and then C vs D and then A vs C to boil it down to an answer."
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7l47je | Why do so many languages have similar words for 'no', but different for the word 'yes'? | For example: English, French and German have no, non and nein, but they use yes, oui and ja. | Other | explainlikeimfive | {
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"I believe it's because having a word for disagreement in Indo-European languages tends to be more universal/fundamental than having a word for agreement. The 'no'-type word emerges early, while the 'yes'-type word emerges later on - because people would have simply responded with 'I will' or 'I am' or 'It is' or 'He will' instead of something like 'yes'. Meanwhile, if they want to respond in the negative, they need some sort of 'no'-type word in order to do so - 'I will *not*', 'She can *not*', etc. Here's an r/Linguistics thread where someone asked the same question: URL_0",
"Looking at only Indo-European languages is not really a good way to see if this is just a coincidence or a pattern that follows. For example, Turkish uses evet and hayir, neither of which are similar at all to English, French, or German's versions of negation and affirmation. In Chinese, we don't have a specific word for yes or no, but they don't sound similar at all to the versions in Indo-European languages. If you were to take Italian, French, Spanish, and Catalan instead, they each use *si* to mean yes in some case. Of course, these are all romance languages. (Portuguese uses sim which is similar.) Meanwhile, German, Danish, English, Swedish, etc. all use similar enough words to mean yes. (Yeah is very similar to ya, which is what the other three languages use for yes.) Meanwhile, I could also bring up Greek, which uses *nai* to mean yes, which sounds more similar to the versions of no found in your example languages. Based on that, my assumption would be that it's coincidental.",
"Actually, among the Indo-European languages, short words that start with “n” are, for some reason, surprisingly stable. The following are English/French/German/Farsi (I added Farsi as an example for a less closely related, but still Indo-European, language): * no / non / nein / na * nine / neuf / neun / noh * new / nouveau / neu / now * name / nom / Name / nâm So “no” just happens to fall into that phenomenon and “yes” doesn’t. At the same time, I feel the need to point out that yes/ja aren’t further from each other than no/nein: the German “j” is pronounced the same as the English “y” and the difference in spelling is just arbitrary. This shouldn’t be surprising given that German and English are both Germanic languages, but French and Farsi aren’t.",
"I just listened to this episode of the History of English today! URL_0 Your specific question is somewhere after the 35 minute mark, but the whole episode is very interesting.",
"yes, oui and ja are similar. yes was probably originally pronounced jāi or (JAW/JAH) So J can migrate to Y think of JAW YAH is a very small phonetic difference so you can see how it changes Also H and S can migrate YAH YAS Now we have YAS and instead of saying AHH for the A sound you actually say the word \"A\" aes Yaes YES"
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7l4iix | why people can’t sleep for a couple years to awaken with enough energy to stay awake for just as long? | Biology | explainlikeimfive | {
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"A main purpose of sleep is to clean up chemical waste products that your brain cells make constantly. If you stay awake for a year, without any sleep time for clean-up, you will in fact die long before the year is over.",
"Because that’s not how our metabolism and sleep cycles work. Without going into detail. Basically what you are asking is like, why can’t we fill up a car with 100000 gallons and drive for 500000 miles?",
"That exceedes the fuel storage capacity of our bodies. Bears can hibernate for months by storing a lot of fat and entering a super low energy state. Years would take even more storage. Staying awake for a long period also requires taking on and processing fuel faster than it is used for daily activity. Humans don't work like that in the wild, so our brains have not adapted to facilitate that. You'd need to make/evolve a significantly different brain to be awake all the time. Probably something like whales do, where the two halves of their brain can sleep/rest independently. One side sleeps while the other side runs the whale. Both sides are needed for the most complex behaviors, but routine operations can run just fine on half a brain."
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7l4jo6 | How can we lie to ourselves/ use self-deception? | How is it at all possible? What happens cognitively and psychologically? | Other | explainlikeimfive | {
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"I studied brain science in university. Contrary to popular belief, the human brain is perfectly capable of believing multiple, contradictory things at once. So we can at the same time know \"I stole this thing\" and believe \"I'm not the kind of person who steals things.\"",
"The part of the brain responsible for 'I'm not racist!\" is not the exact same part responsible for \"But he's big and black and it's late...\". In other words your brain is not a perfectly logical whole that processes each of it's thoughts in relation to the whole. It can process individual thoughts separate from other thoughts and they may not be subject to the same logic - the part that says \"he's big and black\" goes through one danger-will-robinson-pathway and the part that say \"i'm not racist\" goes through the pathway that rather likes to think you aren't a bad guy. And humans rather like to think they aren't bad guys. It's important for health to think you are great, so of course anyone who was able to think they weren't great died off a long time ago and never had babies."
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7l4vkz | Why do drive sizes come in multiples of 4? | Like flash drives, hard drives, and SSDs. | Technology | explainlikeimfive | {
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"Actually, it's multiples of 2. Computers internally do everything in binary (base-2 counting) so things involving them tend to be in powers of 2."
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7l4w1o | Is over-population a self managing problem, or at some point are we going to have to intervene? | Other | explainlikeimfive | {
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"Long term it is a self managing problem. Unfortunately, the \"management\" is mass starvation and wide-spread disease resulting in the death of billions, followed by the crumbling of civilization and a reversion to hunter-gatherer tribes. So we might want to intervene before we get there."
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7l4z2n | What is actually happening when we get "butterflies" in our stomach? | Biology | explainlikeimfive | {
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"When your body experiences a fight or flight situation it responds in ways to get your body ready for action. It amps up your cooling systems (makes you start to sweat), pushes up adrenaline (which makes you feel jittery or gives you the shakes), and shifts blood from non-vital processes to the muscles. Part of that last one is shutting down your digestive system. While it's obviously important to digest food, it's not import to do it right in the middle of a fight. So blood quickly drains from your stomach and intestines, which gives you that stomach drop feeling. It can also cause you to immediately urinate/defecate for the same reason."
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7l57ap | Does sign language provide the predominant message for hearing impaired people? | Or does the lip reading do most of it and the signs are just there for context? EDIT: Who the fuck is downvoting this? | Other | explainlikeimfive | {
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"Note that there's more than one sign language, just like there's more than one spoken language. Deaf people in the U.S. usually speak ASL (American Sign Language), which isn't the same as what's signed in the U.K., Australia, France, or other countries. Oh, and there are regional dialects, too. To answer your question, though, all of those sign languages are complete languages, just as rich and expressive as spoken language. There's nothing that can be communicated via speech or writing that can't be communicated between two people who are both fluent in sign language.",
"Yes, yes it does. Not all deaf people read lips, however. Signed languages are full and complete languages on their own and abide by the same rules that spoken languages do. It has its own grammar and phonology.",
"For one thing, the name of \"sign language\" can probably best be thought of as a family of languages, like Italian and French are Romance languages. ASL, American Sign Language, is what is predominantly used in the USA. Other commentators have explained that ASL is a fully-fledged language. Deaf children are taught in ASL; in previous times, these children were taught lipreading, but it took years and often they would miss crucial information being conveyed. For another thing, lip reading is ridiculously difficult. You need training or years of practice at it, and even then it's not a foolproof method. The sounds /b/ and /p/ (bilabial stops) are pronounced with the same lip movements, so someone lipreading would have to figure out via other means, mostly from context, whether the person speaking is saying either bat or pat, or ban or pan. The sounds /t/ and /d/ (alveolar stops) are pronounced with similar lip movements, same with /f/ and /v/ (labiodental fricatives), along with /k/ and /g/ (velar stops)....etc. The thing that makes these pairs different to our ears and own voice is something called phonation, also called voicing. Phonation happens in your vocal chords. For an example, put a hand to your throat and pronounce these two sounds separately: ffffffffff and vvvvvvvv. (whispering does not work for this experiment). The /v/ is voiced, meaning your vocal chords vibrate when making that sound. The /f/ is voiceless, meaning your vocal chords don't vibrate. Just about all consonants in the English language is part of a voiced/voiceless pair. Articulated in exactly the same manner and place in the mouth, separated by that that little vibrating detail. People who lipread would have to rely heavily on context, either environmental, facial expressions, or by other words said to infer what the speaker is saying. If you try to mouth or whisper the words \"fine\" and \"vine\", nothing changes between those words, and someone watching your mouth would be hard pressed to figure out which you're saying. If you spoke a list of random words to a lipreader, they'd likely have no idea what you're saying, or, possibly, come up with a sentence that made some kind of sense. But a sentence like, \"I put the ham in the fridge downstairs,\" accounting for some variations in accents, could come across as, \"I bit the ham on the vitch town dere's.\" That might come off differently than the first sentence. People who acquire hearing loss suddenly in life might start out with what is called manual sign. These are gestures that might be cherry-picked from sign languages, or might be gestures that only pertain to the user (a certain eyeroll, or knocking on a table, could have a designated meaning in this case), but they are usually simple to learn and few in number. If the person is able, they might go on to learn sign language. But in the case of a brain injury or stroke, which can cause hearing loss, acquiring a new language might be more difficult (both in terms of physical ability and cognitive ability). Manual sign, which is usually designed to be simple and easy, would be used in these cases. \"Key word signing\", where the speaker uses normal speaking and also signs the important context words, is used in some speech therapy to help a developmentally/intellectually disabled kid (or adult) to acquire speech. Signing the key words helps the kid connect the signs to the word, and signals what words should be paid attention to. (It's a little more complicated than that, but I don't feel like hunting for it in my textbook this late at night). You might be getting downvotes because the subject of sign languages being as full as any spoken language is still controversial for many people. It's only been in recent decades that deaf children were encouraged to learn ASL. Before, and still even now, parents were worried that if a deaf or hearing-impaired child was taught ASL, it would prevent them from developing spoken language (which has been proven false, by the way). Parents much preferred waiting to see if their child would develop normal speech, which in actuality made them miss out on crucial learning periods, and then gave them voice coaching to teach them to speak. I'm uncertain whether they expected the child to 'pick up' lipreading or taught it. But. Even the first school for the D/deaf did not have a deaf president for many years, and accepted a large portion of hearing students, the school board believing that any deaf person was not qualified enough to run the school; until students protested and demanded an ALL deaf school (After that, the board chose a person who acquired deafness later in life, and he spoke instead of signed his speechs; this angered about half the Deaf population who hated the stigma against sign language, but it appeased the students enough). Nowadays, the current controversy is over cochlear implants.",
"1) Think for 2 seconds : lips reading would mean that you already know the language of that person. I you don't understand French and I speak French, what use will lips reading be ? 2) Sign language, as others have pointed out, is actually sign language**s**, BUT these languages have a lot in common, meaning that an American could have a conversation with a European in sign languages, without having to learn any of the European languages at all. This has actually happened to me, as I was working as a translator : I saw people from different countries who hadn't the slightest clue in other people's languages having conversations in sign languages, even having fun at noticing the slight differences between the signs used for this and that in each language. That was a pretty humbling experience, as I've been studying Japanese for more than 10 years and suddenly saw people who never did having fluent conversations with their deaf Japanese colleagues. A true WTF? moment."
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7l5p2s | Why does red light seem 'weaker' than other colors? | This year we bought a pre-lit Christmas tree. The LED lights can be set to slowly cycle through a range of colors. With the tree providing the only light in the room, I can read just fine when the lights are shifting through the white-green-blue part of the cycle but it's harder to read when they're purple. And it's impossible when they're fully red; the room looks noticeably darker too. Does everyone experience this? Is it an issue with the lights or with my (and my wife's) eyes? | Biology | explainlikeimfive | {
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"[The human eye isn't very sensitive to reds]( URL_0 ). I can't say exactly how your LED system works or if it's actually outputting the same light intensity in the different colors, but all things equal a red light will seem dimmer to the human eye."
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7l5t50 | What is haemachrmoatosis? And what long term affects does it have on someone's life? | Biology | explainlikeimfive | {
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"Hemochromatosis is a type of blood disorder where the body absorbs way more iron than normal into the bloodstream. Normally the iron would become part of a red blood cell, but in such high levels, the iron has nowhere to go. As a result, it starts to build up in areas such as the liver, joints such as the knees and elbows, or kidneys. This disorder can present in a simple way, such as joint pain, but could also present in more serious ways, such as liver disease. Furthermore, a \"cure\" doesn't really exist, so treatment is lifelong. The primary treatment is blood-letting, which is literally draining blood from the body so that the extra iron stuck throughout the body gets used up making new blood. A Low-iron diet may be necessary as well, with the goal being to try to keep the amount of extra iron that could be absorbed into the body as low as possible. It is a balancing act that is likely to be developed over time with your doctor/dietitian. Finally, because liver disease is one of the real threats of hemochromatosis, alcohol is generally frowned upon as well. The long term effects are determined mainly by how well the disorder is managed. If the correct diet is kept, and blood-letting occurs regularly (every couple months with a good diet), a normal life is a very real thing. Hope this helped!"
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7l5y9n | How does lactic acid form and just disappear? Also how does it not harm any parts of our body? | Biology | explainlikeimfive | {
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"Lactic acid is produced in your muscles as a byproduct of prolonged anaerobic exercise. The amounts produced are typically so small it can easily be removed through the bloodstream and processed in the kidneys, and do not present any danger. Certain disorders can cause lactic acid to build up faster than the body can remove it, and that can cause serious problems. Note there has to be something wrong with you for this to happen, it is not the result of too much exercise.",
"Cells make lactic acid when they don't receive enough energy. It is like the \"Plan B\" of the metabolism. For example, during an intense workout, your muscles might make lactic acid to keep up. This is harmless in small amounts. The problem is when there is too much lactic acid. This occurs in serious diseases such as sepsis (systemic infection). Too much acid in the body is dangerous and leads to a series of medical problems (metabolic acidosis)."
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7l60z8 | How come certain sodas (such as root beer or grape soda) are almost always caffeine free? | Chemistry | explainlikeimfive | {
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"Caffeine is in colas because they were originally made with the kola nut, which has caffeine. There's nothing in the ingredients of a rootbeer that would normally cause caffeine to be in the beverage unless you choose to add it.",
"I think it makes more sense to reverse the question, why is there caffeine in some sodas? Afterall soda is just carbonated water with some sugary flavour added, where does the caffeine come from? And root beer and grape flavours don't have caffeine naturally in them, as is the case for most other soda flavours too. But as ameoba explained, colas have it naturally, then some followed, maybe symply because coke was so successful, maybe because they wanted it to be a coffee substitute(?). But the norm is that there is not normally caffeine in a soda."
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7l660h | Why is it that when we eat something spicy, we get hiccups? | Biology | explainlikeimfive | {
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"I have not experienced hiccups after eating spicy food (And I eat it on a weekly basis) , nor have I seen or heard of this before. Could be the chemicals like capsaicin annoying the lungs.",
"I have acid reflux and get the hiccups after eating a lot of things, including spice, or too much food, or alcohol. Spicy foods are linked to acid reflux, which is a combination of a relaxed stomach opening and movement of the stomach acid up from the stomach back into the esophagus. When this happens, it can irritate the diaphragm and that can cause contractions, and then the irregularities in breathing that are hiccups. So if you're always getting hiccups after a spicy meal, try chewing some tums after you're done eating."
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7l6dqi | Why is blood not attracted to magnets? It has iron in it. | Saw a post earlier about blood and magnets. Why does a large magnet not cause problems with the circulatory system? | Biology | explainlikeimfive | {
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"Iron in blood is not in bulk form (clumps of iron), but in molecules such as haemoglobin, which are *not* ferromagnetic compounds.",
"Blood is not attracted to magnets, because the amount of iron is very *very* low, also not all metals are attracted by magnets, some are repelled. This is the case for the iron in our blood, a very strong magnet will actually repel the blood, but in a very minor magnitude. More info: URL_0",
"Stainless steel has iron in it as well, and it is not magnetic. That's because all forms of iron are not magnetic. Pure iron and certain iron allows and compounds have free electrons that behave in a special way that makes it magnetic. Iron in stainless steel and hemoglobin does not."
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7l6o88 | cough medicine, how does it work? | Biology | explainlikeimfive | {
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"Pharmacist here. It depends on what cough medicine you’re talking about. Antitussives (dextromethorphan/Delsym, codeine) suppress the cough mechanism in the brain directly. Codeine is an opioid typically used for pain, but all opioids have a secondary effect of suppressing the cough reflex through direct action on the brain. This is also how people die from opioid overdoses, brain mechanism that controls breathing is stopped. Expectorants (guaifenesin/Mucinex) break up mucus and phlegm in the lungs, making it easier to cough up. Some studies show this is no more effective than drinking water. A personal favorite of mine is benzonatate/Tessalon Perles which are gel-like pills that melt and cover the stretch receptors on your lungs to desensitize them so you cough less. Has worked wonders for me before. In the end, a cough is typically related to the common cold virus and you can’t do much to get rid of it. Your body can clear it anywhere from 1-3 weeks usually."
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7l6qng | Why does car exhaust have such a stronger smell during the winter months? | Chemistry | explainlikeimfive | {
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"The engine runs richer (more fuel) especially at engine start-up until it gets to normal operating temperature. The extra fuel is why the exhaust smells stronger.",
"Your car has a catalytic converter that, amongst other things, breaks down any unburnt fuel. Unfortunately, for the converter to work it requires a temperature of about 425C (approx 800F). During winter, it is much cooler and more difficult to heat the catalytic converter up to a temperature where it is working efficiently, resulting in a higher amount of unburnt fuel, which is what the smell is."
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7l6u63 | How does the application of duct tape to a wart actually remove it? | Biology | explainlikeimfive | {
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"Duct tape has a solvent in it. That solvent dissolves your skin when you leave it sitting there forever. That dissolves the wart along with a lot of the skin. If the wart is entirely killed off the skin will repair itself from the surrounding area minus the wart. It will probably leave a small scar. You can get a much safer and less 'this fucking hardware chemicals in your bloodstream' version from the pharmacy area for 20$. Wart-off, or whatever. I assume you're talking about planter's warts, because duct tape will seriously injure you if you use it on something as sensitive as a genital."
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7l6vtd | Why do pharmaceutical commercials have to say don't use the medicine if you are allergic to it? Shouldn't that be obvious? | Other | explainlikeimfive | {
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"No, it's not obvious. Drugs are given cute names by the marketing guys, that don't really clue us in to what the ingredients are. The fact that drug companies are allowed to advertise at all is a huge problem. Promising Jim Bob the drop-out a cure for a disease that he didn't even know he had via advertising is a terrible idea.",
"Not necessarily. Drugs often go by one or more brand names in addition to their scientific name. It might later be reformulated and combined with another drug under a new brand name. You may know you are allergic to Claritin without realizing that also means you are allergic to loratadine, Alavert, Walitin, and Loradamed. Also, the same drug can be used for different conditions and applied in different ways. Someone might not realize the Benadryl cream for their rash is the same medicine as in the Benadryl pill for your allergies. Finally, a lot of drug names sound the same, I people might not remember. The important message is that they might be allergic and should check."
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7l6ytc | Mathematically, if you add an infinite sum of decreasing positive numbers, how in the world can you not reach infinity? | Suppose you had an equation that was the sum of infinitely many terms, and each term is equal to the following equation (where *n* represents that number's placement in the equation; so for the first term in the sum equation, n = 1, the second term in the equation has n = 2, etc.): `number = 1 / 10^(n-1)` So the first number in this sequence is 1 over 10 raised to 0, or 1 over 1, which is 1. The second is one over 10 raised to 1, or one-tenth, 0.1. The second number is one over 10 squared, or 1 over 100, 0.01. Suppose you add up an infinite number of these terms. You'll get something like... `1 + .1 + .01 + .001 + .0001 + .00001....` Now technically speaking, the number you will get with this infinite sequence of number is `1.111111111111.....` with an infinite number of trailing decimal ones. But since you are adding up an **infinite number of positive numbers**... # How in the world can you NOT be reaching infinity?! How can an infinite number of positive numbers not equal infinity? It's fascinating to me. It sounds counterintuitive; paradoxical. If you are interested, the 0:00-1:50 mark of [this video here]( URL_0 ) is the inspiration for this question. | Mathematics | explainlikeimfive | {
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"> But since you are adding up an infinite number of positive numbers... Yeah, and each one is smaller and smaller than the last. If you do it in steps, each number you get is larger than the last, so you'll always get a bigger number after you add the next step. However, since you're adding a smaller and smaller amount each time, you'll *never* be able to pass a particular threshold. How could you ever get to \"2\" in that sequence of 1's? If you \"reach\" infinity, you would have to necessarily eventually stop at some number greater than 2, and yet, that's impossible.",
"This is a case where your intuition is not serving you well. There are many situations where summing an infinite number of values produces a finite result. You've got the math right in your post - develop your understanding based on that, rather than on the popularized notions of infinity that you otherwise hold.",
"> adding up an infinite number of positive numbers What does it mean to \"add up an infinite number of positive numbers\"? This is a concept that is hard to understand. But worse than being hard, it seems like it is kind of fuzzy, and might mean different things to different people. Math is not supposed to be fuzzy, it is supposed to be about precise logical truth. So instead of adding infinitely many numbers, let's think about adding finitely many numbers: ``` 1 + .1 = 1.1 1 + .1 + .01 = 1.11 1 + .1 + .01 + .001 = 1.111 ``` Now the number we get always seems to be less than 2. Is it less than 2 if you add up 5 terms? How about if you add up 100 terms, or 1000 terms, or 1,000,000 terms? Is there any number of terms you could add up to get a result that's more than 2? Take a minute to think about this. See if you can convince yourself that the result, no matter how many terms you add up, will always be less than 2. Now the results of adding terms are the numbers `1, 1.1, 1.11, 1.111, ...` Mathematicians call these *partial sums* (because you're not adding up infinitely many terms, you're only adding the first part of infinitely many terms). Hopefully you've convinced yourself that 2 is greater than each partial sum. Mathematicians like to summarize the relationship between 2 and the partial sums by saying that \"2 is an upper bound of the partial sums.\" Is 5 an upper bound of the partial sums? What about 1.5? 1.2? What about 1.11115? 1.11110? The *precise definition* of the sum of infinitely many terms is the number that the partial sums approach [2]. If the *partial sums* are bounded above by 2, the *infinite sum* can be, at most, 2. Mathematicians like to make upper bounds precise, if they can. What is the most precise possible upper bound? If we expressed in decimal form, what would it look like? Convince yourself that it would *have to look like* 1.111111... -- does such a number exist? It looks an awful lot like what you get if you punch `10/9` into a calculator. Is `10/9` our upper bound? Is it also a lower bound? What's the best lower bound you can find? We've fallen down quite a rabbit hole of ideas here. After being somewhat stagnant in the Dark Ages (at least in Europe), math was jump-started in the 1600's by the famous discoveries of Isaac Newton (and less famous others like Gottfried Leibniz) about how to deal with infinitely large and infinitely small things. Mathematicians were very excited about all the new applications to science and technology, and they weren't always really careful in their thinking about these new ideas. Then in the 1800's through the early 1900's, various paradoxes and other logical problems were pointed out, and many very smart people in the mathematical community spent many decades thinking very carefully about the wide variety of ideas meant by the word \"infinity,\" refining them into precise technical concepts, and making sure all the related conceptual questions and details are completely solid. 3rd-year college math majors usually take one to two full semesters of coursework about these topics, and in that time can only begin to coming to grips with the depth and complexity lurking behind the word \"infinity.\" [1] So when mathematicians talk about infinity, they are usually using it as a short-hand for some more precise idea. There are a lot of different ways of thinking about very large numbers, so \"infinity\" or \"infinite\" sometimes means *a different precise idea depending on the context in which the word is used*. [2] This definition is a more precise definition than what you've been working with, but it's still fuzzy. What is meant by \"number\"? What is meant by \"approach\"? What happens if there is no such number? The mathematical community's established widely accepted answers to these questions, but I won't go into the details here.",
"I'm going to take a crack at a more intuitive answer that is hopefully closer to what 5 year old can grasp: Lets say someone moves closer to a destination ten meters ahead of him every one second, but only moves half of the remaining distance each second. The first second he moves 5 meters, the next he moves 2.5, the next he moves 1.25 etc. Each second he gets closer to the destination, but he is also only moving half of the remaining distance each time. So he can never really reach it. This is identical to your example problem, except in that case you're starting at 1, and are always moving one ninth of the remaining distance closer to 2.",
"Super short version: Lets say we did this a lot: 1.111111111111111111111111111111111111111111111111111111111111111111111111 No matter how many ones we add, the resulting number will never be greater then 1.2 > 1.2 < infinity So yeah..."
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7l72ii | Why does sunburn feel hot/warm to the touch even days later? | Biology | explainlikeimfive | {
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"The sun doesn't really burn your skin. The UV-B radiation is damaging the cells in such a way that the cells themselves will self destruct. Those dead cells trigger inflammation, which is what makes your skin warm to the touch. And yes, the inflammation is related to increased blood flow. It's a part of the healing process to replace the now dead cells."
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7l75vp | Is it possible to "catch up on" nutrients? | Like say you ate all meats on Monday, and then all fruits on Tuesday, would you end up okay? If so, would it still work if the delay was a week rather than a day? | Biology | explainlikeimfive | {
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"Your body requires certain micro-nutrients (basically vitamins & minerals), which it can't produce on it's own in order to properly rebuild & maintain certain types of tissues. We're fairly good at storing them, but stores will diminish & signs of deficiencies will usually occur after a few weeks depending on which one we're talking about. As to your question, (assuming daily caloric needs are met on this diet) these stores work on a ~weekly basis, so yes you could \"catch up\" in a sense with micro-nutrients, but eating a diet of mainly animal protein one day or fruit the next--and much more so on a weekly basis--will most likely cause intestinal distress as well as cholesterol & insulin heavy days, which could tax your system & increase your risk for various metabolic and/or heart disease. Which is why a balanced daily diet is clinically recommended and easier to maintain."
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7l7dcs | Why is it that when we have a nap for 20 minutes and wake up we feel fine and when we have one for three hours we feel knackered? | Biology | explainlikeimfive | {
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"Actually not exactly. We sleep in cycles. That's why sometimes after sleeping for many hours you feel great, and other times not so much. It all depends on if you wake up in between cycles or in the middle of one. Your deepest sleep is in the middle of a cycle and you don't want to interrupt that if you wanna feel great when you wake up.., ....or (to really answer your question) one solution instead of figuring out when to set your alarm for in between cycles is to just take a nap for 20 minutes or less. This is because when you first fall asleep it will take about 20 minutes for the cycle to start. Taking a short nap will insure that you don't interrupt deep sleep"
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7l7ulu | Deep Fried Ice Cream | How can ice cream be deep fried? Why doesn’t it just melt when put into boiling cooking oil? | Physics | explainlikeimfive | {
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"The ice cream itself is not fried. It is surrounded by batter (like a donut) which is fried -- quickly enough that most of the ice cream doesn't melt, especially as the batter acts as a heat insulator.",
"The ice cream is frozen super-hard - like it's almost impossible to cut, that hard. It's dipped in batter, and then very quickly deep fried. This is also how they make Baked Alaska - which is that same rock hard block of ice cream frosted with a thick meringue and then quickly baked in a very hot oven.",
"Consider putting a baseball in boiling water. As soon as you put it in, the outside of the baseball is immediately at 212F/100C. A short distance inside, it's getting warmer quickly, but isn't up to boiling yet. A little farther from the edge, it's getting warmer more slowly. In the very center, it's eventually going to get warm, but it changes very slowly, so it will take a long time. The same thing is happening with deep fried ice cream in terms of the ice cream melting. Now, the deep fried ice cream has two advantages over the baseball - it has a layer of batter outside that's the only part that actually need to get fried; and it's frozen at an extra cold temperature to begin with. So you throw it in, the batter on the outside gets hot and cooks almost instantly, and the inside is still cold. One side-note: Some of the ice cream definitely must liquify, you say, if it's in contact with batter that's getting cooked. This is true, but remember that it's a big ball of ice cream with a center that's quite a few degrees below freezing. Wait just a minute, and that cold mass will have sucked the warmth right out of the very outside layer of briefly melted ice cream, and it will have recongealed."
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7l7zhc | What is turbulence and is it something to worry about when flying? | Physics | explainlikeimfive | {
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"Air is moving around more than we give it credit for, and has parts with greater and lesser density, temperature, and humidity. When a plane crosses a boundary between two areas of air that are different in their movement, density, etc., it causes changes to the aerodynamic forces on the plane - it can lift it more or less (the main effects), and also slow it down or allow it to accelerate some. But to answer your second question, no, you should not be worried about turbulence. Aircraft accidents are meticulously analyzed, and only a very tiny proportion of them are caused by turbulence. If you want to get worried about things while flying, worry about wing icing, pilot fatigue, faulty cockpit instrumentation, insufficient fuel, and other maintenance lapses, before you worry about turbulence. And above all else, when you're flying and get nervous because of turbulence, don't forget there hasn't been a fatal plane crash of an American commercial flight for coming on 20 years soon, and that absolutely every day of the year, probably several times per day, an aircraft flies the exact same route you're flying without crashing (often in worse conditions), let alone all the other airplanes flying all the other routes they fly every single day, also without crashing."
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7l84zz | How does Switzerland's politically neutral stance work? What protects them from external threats? | Other | explainlikeimfive | {
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"1st: money. During WWII they stored nazi gold and allied money. 2nd: it's a mountainous country with a militia-style army (in theory every man is in the army and has a weapon at home) and they have plans and preparations in case of war that would completely close off the country, everyone would evacuate to the mountainous regions and fight guerrilla style. Basically invading Switzerland would be extremely hard and costly for anyone and not really worth the trouble.",
"They are not protected against external threads. In the war they simply never choose a side (at least officially) and the country itself is not that big, important and has a special landscape that makes it essential for conquest. Even worse, an attack on them would be slowed down greatly, because they would destroy Bridges and tunnels, so because of the landscape, it would be hard to gain and keep territory.",
"So lots of people have answered the second half, and I'd endorse those answers (and add that of them it's Switzerland's relatively speaking very large and modern army and hostile geography that has the biggest effect) but I think the fact that you are even asking the second half is because you don't know the answer to the first half. All that Swiss neutrality means is that it won't take sides in an external war. If you want a war with Switzerland you are going to have to invade Switzerland, otherwise Switzerland's not going to join in. It is true that by-and-large Switzerland will avoid taking contentious or extreme positions on matters of geopolitics and global peace and security in order to not put themselves front of any firing line, and that until around 2000 they didn't join any international institutions like the UN lest they compromise their independence, but those were more like guidelines for staying out of trouble than hard and fast rules. Also none of that precludes Switzerland from building alliances, it's just those alliances aren't military. They still mean that a ring of countries around Switzerland are well disposed to Switzerland and wouldn't let an invading army through. Switzerland has many ways of proving its worth to its neighbours. Many of you have mentioned the banking sector but Switzerland is also a great place to discuss diplomacy and trade - it's neutral territory for all sides after all. So it has the second largest UN hub, and is the HQ for the Olympics, Fifa, ICRC, the World Economic Forum and countless investment banks and global brokers. It's worth also remembering Switzerland's history: throughout the Middle Ages Switzerland didn't really fight a single war. But virtually every single war in Europe at the time was largely fought by armies of Swiss mercenaries - often on both sides. I think in people's heads the idea of neutral Switzerland is of this tiny skinny kid hiding in the corner of a barfight. I think of Switzerland more as the too massive to fuck with bouncer on the door who's not going to take sides in your fight but *do not* punch him.",
"The answer is money, money and money. Anyone with enough power will already have their money hiding there. Even warlords like to make sure their personal finances are safe!"
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7l8mjm | Flinch Reflex or Flinch Response: That split second reaction to an incoming threat (i.e. When you're about to get hit by a ball in the face and parts of your face recoil prior to contact/impact) ?? | Biology | explainlikeimfive | {
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"The human body has evolved and fine-tuned to protect itself from danger. Virtually all involuntary responses can be defined as defense mechanisms, though some are more discrete than others. When the brain perceives a threat (i.e. an object hurdling towards your face), it sends a neurochemical/electrical signal to the neurons that activates your face muscles to recoil, scrunch up, turn away, etc. The recoil may make your muscles more rigid so the object will bounce off to lessen the damage. Our eyes also close to protect them. Your facial movements signal to others that you’re in danger and need help. This has been perfected through thousands of years of evolution, and also in your own life. As you learn more and experience more threats, your brain adapts to respond to them. Another classic example of this is a child putting his hand on a hot stove, which he quickly learns not to do.",
"The flinch response is an interesting study. Take [this picture]( URL_0 ) for example. You'll notice that everyone is focused on the bat flying thru the air. Almost all of their responses look identical - arms up at a 45 degree angle, fingers splayed, head turtled down into their shoulders. It's an automatic response that is hard wired into our bodies. Now take a look at [this picture]( URL_1 ). A lot of people are displaying a flinch response, including the little baby in pink. She doesn't know why, but she's flinching. The guy getting clocked with the bat doesn't react. Why? Because he didn't see the threat coming at him, his eyes were looking at something else (like someone walking up and down the stairs next to him). The difference between the two pictures? Notice the bat is broken in the first picture. That means there was an audible \"crack\" that alerted everyone, including those not paying attention to the game. The second picture, the bat is intact, meaning there was no audible warning - only those who saw it were alarmed. See the lady eating popcorn? She has no idea there's a bat flying thru the air. Also interesting to note, is that everyone in both pictures who have something in their hand, tightened their grip on whatever they have. No one dropped their drink. The lady keeping score in the second picture raises her arms in a flinch reflex, but her hands tightened around her clipboard instead of dropping it. She even has the pen in her hand and it's still on the paper. Notice that everyone without something in their hands spread their fingers wide for more protection. This is taught to police officers (or in decent self defense courses) to not hold their ticket book or radio while confronting an irate suspect, as their flinch response to an attack would almost always result in the officer not dropping the object in their hand while they get beaten. When we get a full on surprise, like in a haunted house, this is a full flinch. Our brains try to override the flinch, in order to not look stupid. A flinch is not just scrunching and jumping a bit, we do a \"micro flinch\" for lack of a better term."
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7l9gdm | How do push notifications arrive almost instantly after transactions occur? | If I'm buying something that triggers a push alert, sometimes it seems like I get the notification an instant after swiping my credit card. Considering we're told that streaming video or loading web pages can be slow because of the number of connections across the Internet, how does a transaction process fast enough from a credit card swiper to get to my phone so fast? | Technology | explainlikeimfive | {
"a_id": [
"drkuyoj",
"drkiyjr",
"drkjabd"
],
"text": [
"Obviously different companies will use different technologies, but I'd bet a fair amount use [Firebase Cloud Messaging]( URL_0 ) (formally known as Google Cloud Messaging). At least on Android, there is a connection to the Firebase Cloud Messaging (FCM) that all apps on the device share. When a transaction occurs, your bank might send the FCM servers a request to display a notification on your phone. The FCM servers will then use that connection from their servers to your device to send a very small message to your phone. | Bank | --- > | FCM | --- > | Phone | This message is probably even smaller then this Reddit post. Just a couple bytes (1 byte = eight 0s and 1s). Since it is so small compared to a movie (which can be several gigabytes, 1 gb = 8000000000 ones and zeros) the message can basically be received instantly, and in just one message (movies have to be split into thousands of smaller messages to and from the server). The time it takes the message to physically reach your device is very very small to humans. Worst case it would take a second, normal case probably 100 milliseconds. Edit: look at edman007's answer to see why it is important that all apps on your phone share one connection to FCM. And how this helps the speed of a message being sent.",
"It's a very light package like a txt message being sent containing only the title. The app is already in your phone to put the notification presentation. Then you click the notification so it fetches the rest of the details.",
"There are two aspects to internet speed, latency and speed. Latency is is how long it actually takes data to get from one point (measured in milliseconds typically), speed is how much data can move in some period (measured in Mbps typically). Phones are typically high for both, when they are in a power save mode the transmitter powers down, and when you need to use the internet it can take a full second under 3G to switch to full speed, I think 4G is a little faster here, I'm not sure. Once connected, even via something like 3G, you could easily get 100kbps (considered very slow by today's standards), and the latency on this connection might be high, like 100ms. Now, Youtube is slow on that connection because a video might not play until 1MB has been downloaded, at 100kbps there is the startup latency (~1s) plus connection latency (typically get hit twice) for a total of 200ms, and then the time to download that 1MB (10.49s), so Youtube takes ~11.7s to load, very slow. A push connection is different, first it's already connected so you skip the connection latency, and just are hit with the response time which would be closer to 50ms. Second, it's typically little more than the worse you see on the screen, for 500bytes is reasonable. 500bytes at 100kbps takes 5ms to download. So if you're already using your phone and don't need to startup the transmitter it should take 55ms which is instant as far as you can tell, if you need to startup the transmitter then you might add a second, for a total of 1 second."
],
"score": [
5,
3,
3
],
"text_urls": [
[
"https://firebase.google.com/docs/cloud-messaging/"
],
[],
[]
]
} | [
"url"
] | [
"url"
] |
7l9iua | what makes a drug a drug, if a drug has a physiological effect then wouldn't everything we consume be considered a drug? | Chemistry | explainlikeimfive | {
"a_id": [
"drki5gc"
],
"text": [
"> [A drug is any substance (other than food that provides nutritional support) that, when inhaled, injected, smoked, consumed, absorbed via a patch on the skin, or dissolved under the tongue causes a temporary physiological (and often psychological) change in the body.]( URL_0 ) The key is that it's something that's *not normally needed* that changes the standard chemistry & operation of your body. You might argue that this is a completely arbitrary distinction but language is full of those."
],
"score": [
6
],
"text_urls": [
[
"https://en.wikipedia.org/wiki/Drug"
]
]
} | [
"url"
] | [
"url"
] |
|
7la3li | FPTP Voting | This has apparently been made the voting system of choice for all elections in England - have read up online but not 100% getting it. | Other | explainlikeimfive | {
"a_id": [
"drkmulk",
"drko7lr"
],
"text": [
"My understanding of FPTP voting (and its problems!) is explained pretty well in this youtube video. As far as I know, in \"First Past the Post\" voting, the candidate who gets the required number of votes (either the most, or the majority, or a set percentage) wins. URL_0",
"FPTP is probably more succinctly explained as \"winner-take-all\" where each person can select one candidate. For example, the U.S. Congress. For each district, there is one election and one seat that can be won. A bunch of people enter the race, and whoever gets the most votes wins. They don't even need a majority; could be there are 99 candidates and all of them but one get 1% of the vote; the one with 2% would win (although in practice this sort of thing rarely happens; the rules generally favor having as few candidates as possible) In contrast, take for example majoritarian voting, where no candidate can win unless they have at least 50% of the vote. If no candidate wins in the first round, the worst-performing candidates are disqualified until one has at least 50%. You can also have instant-runoff votes where you can vote for multiple people ranked in terms of preference. Or a proportional representation system, where instead of voting for candidates, voters choose a party list. If a party gets X% of the vote, they get X% of the open seats."
],
"score": [
5,
5
],
"text_urls": [
[
"https://youtu.be/s7tWHJfhiyo"
],
[]
]
} | [
"url"
] | [
"url"
] |
7lai2x | Ketosis | how does eating high fat diet make the body burn your own fat? i want to believe, but it's confusing.. | Biology | explainlikeimfive | {
"a_id": [
"drkqm4z"
],
"text": [
"Getting into ketosis isn't necessarily the addition of fats, but the lack of glucose. When glucose enters the body, it is stored as fat. With the lack of it, the body burns the fat your body has stored instead of glucose. Also, keep in mind, all fats aren't bad like everyone makes them out to be. Monounsaturated Fat and Polyunsaturated fats can actually be very healthy for you in the right quantities."
],
"score": [
20
],
"text_urls": [
[]
]
} | [
"url"
] | [
"url"
] |
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