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7e5xrx | Why do voice actors typically record their lines separately? | Other | explainlikeimfive | {
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"On big projects it’s usually a scheduling problem. When using A-list celebrities, they have to work around their insane schedules, and it’s just easier to schedule them when they can come in. Ideally, voice actors would read together. I remember hearing on the Simspons DVD audio commentary that in the early days, before any of the actors were famous, they would always record together. Then, as the show got big, and subsequently the actors got famous, it became too difficult and now they record separately."
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7e5yqq | Why does our body subconsciously lean forward or stand when there is an intense moment happening (Like during a hard boss fight in gaming)? | Biology | explainlikeimfive | {
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"Fight or flight. You’re stressed and your body is getting into position to fight or runaway.",
"So basically your brain doesn't know that you're watching tv or playing a video game. All these lights and sounds and shit stimulate the \"sympathetic\" half of your nervous system. (As opposed to parasympathetic but that's not all important). So your sympathetic nervous system or \"fight or flight\" response causes: 1 increased heart rate 2 the tubes in your lungs (bronchioles) to expand 3 your blood vessels and pupils to dilate. 4 I'm pretty sure there's a 4th one but I can't remember it. So yeah it's pretty much just that all these visual and auditory stimuli trigger a sympathetic response, cuz you're brain is stupid and doesn't know that the stimuli are just on a tv screen"
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7e63du | How do market crashes happen? | I understand how it could happen over time, but how is it possible to not see one coming because it happens so fast. It's just confusing. | Economics | explainlikeimfive | {
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"Markets serve two functions: 1 - they connect buyers and sellers so if you need/want something you can get it efficiently; and 2 - they help determine prices. I assume you are just a random dude sitting in America somewhere and you have no idea what a ton of Egyptian Cotton costs or is worth. Before \"markets\" if I transported you to an Egyptian cotton farmer's field and told you to negotiate with him for the purchase of a ton of his cotton you would have no idea what you were doing or what to offer. Today if you find yourself in need of Egyptian cotton you can purchase it as a commodity at a price that is fair based on what everyone else in the world is paying. Nice and easy. The problem with markets however is that they often set prices that do not reflect the value of what is being sold. There are a lot of people who will disagree with this and say (foolishly) that \"value is whatever someone will pay\". However the phenomenon of a crash is caused by this very disconnection. Prices go up for some irrational reason and they in fact go up so high that when they come down they create an inverse irrationality that pushes them below their value. Most crashes result in over-shooting the real value and there being a rebound later. The takeaway from this is just that human beings are irrational creatures and our irrationality is reflected in market prices for goods. A crash is simply the hardest form of evidence of this irrationality. Like most cognitive defects though, most people can only see it in retrospect.",
"/u/Not_Legal_Advice_Pod explains it well. Another way to look at it is: Its called a 'Crash' because it is rightly so - A very sudden drop from a cliff. Markets always have ups and downs. The ups are usually slower and take up multiple peaks through the course of time, going upwards with each period. During this period, everyone involved makes some money - the ones who got in first, the ones who come in later, and so on, because everyone gets a piece of the upward trend, one after another. Well, almost everyone, except the ones who bought at the peak. In other words, through a course of time, there are enough buyers and sellers in the upward trend towards the peaks. When it falls (read 'corrects'), it is basically a panic which reads - 'Get out or you will lose it all !' That results in too many people trying to sell, hardly any wanting to buy, and thats a perfect crash for you."
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7e65ev | how’s come sometimes when your leg falls asleep it doesn’t hurt, and other times it tingles with intense pain? | Biology | explainlikeimfive | {
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"I don't know if this is 100% but I heard this somewhere at uni and it's an explanation for now. The body always have feedback from nerves and receptors. When overloaded with feedback or when the feedback system is stopped the brain panics and can cause pain. Apologies if I am wrong but I am sure my lecturer said this once. But in much great detail etc",
"I’m not exactly an expert on this, but from what I’ve gathered the intense pain and sensitivity (often described as pins and needles), is caused by lack of blood circulation. That said, I have no clue why it causes physical pain, but I noticed nobody else had replied so I figured this might at least get you started on a quest to conquer google and find the answer",
"The phenomenon you are referring to is called “distal paresthesias due to (in this case temporary) nerve compression”. Known by most as ‘pins and needles’, it is the medical name for the alternating tingling, pain, and numbness you would feel if sitting in one place for too long. To answer your question (like you are 5), let’s compare your body to the lights in your neighborhood. Some of the lights are useful at school, some of them are used at the mall, and others provide light at home – essentially, every light has a job in a different part of the neighborhood. If part of your neighborhood loses power, then those lights will not work. Your body works the same way, but it uses oxygen for power instead of electricity. Your blood vessels are wires that deliver power to your body. If you squeeze the blood vessels too tight, for example by sitting on them, the power to that part of the body cuts off. What do you do when the power goes out? Call the power company! Your nerves send pain signals to the brain letting it know the power is out. However, it would be hard to make a call if you have bad reception. Pressure on the nerve can stop the signal from reaching your brain. In that case, the power company (ie your brain), may or may not be aware a problem exists."
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7e677p | Why can some people match pitches (music vocal) naturally and some can't? | Biology | explainlikeimfive | {
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"Everyone has natural talents. Having a talent means that you can develop a skill faster, and often that you start at a higher skill level when you start training the skill. Musical ability, athletic ability, artistic ability, mathematical ability, linguistic ability, and virtually all other skills and actions that humans take have talents associated with them that some people are born with and that some people are not."
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7e6b3g | What components makes batteries (Ex: Duracell) last longer than others | Technology | explainlikeimfive | {
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"Electrolytic manganese dioxide (EMD). Manufacturing EMD for batteries is hard. You need good purity, the right crystal structure and many other factors to make a good battery from it. It is not marketing bullshit, as /u/T3Kgamer suggests. URL_0"
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7e6bfm | Is it possible to carbonate a flammable liquid such as naphtha or kerosene? If so; what would happen? | Chemistry | explainlikeimfive | {
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"Yes. All that would happen is you'd get fizzy kerosene. It wouldn't be particularly interesting, and the CO2 would displace oxygen in the engine so it'd be a lot less efficient."
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7e6hq7 | Why haven't we gone back to the moon? | Other | explainlikeimfive | {
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"Scientific advancements in ER the past few decades still don't change the fact it costs a ton of money to go out there."
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7e6llt | Why does the sky turn green before a tornado? | Other | explainlikeimfive | {
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"It’s the reflection of sunlight off the back of every frog being held aloft by the tornado’s windy vortex. This intensity varies according to season, and density of wetlands nearby.",
"Thunderstorms happen more often in the afternoon, where the lower parts of the atmosphere experience a reddish tinge of light (think sunset) and the upper parts still are blue. Since tornadoes are found at the bottom of enormous clouds, you get a mix of colors from both effects, and [red and blue make green]( URL_0 ). Any large enough cloud in the afternoon will make the sky a similar color though, it doesn't necessarily mean a tornado will occur. Edit: or lots of flying frogs"
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7e6msc | How does our body get used to the temperature of a cold pool or a hot tub over time? | Biology | explainlikeimfive | {
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"Your body contains nerves to tell you what's going on around your body. Some of those nerves are good at constantly telling you what's going on, for example when you're sitting down, it can tell you that there's pressure on your butt. Other nerves just let you know when there's a change, for example when you're wearing a shirt, you don't always feel the shirt, you can forget that it's there. In a cold pool or a hot tub, where the temperatures aren't considered dangerous, the nerves that are activated are those that sense a CHANGE in temperature. When you \"get used\" to the cold pool or hot tub, it's really just your nerves not sending a signal because there's no further change.",
"Essentially it just cools/warms the skin where all your nerve endings are. Your insides should still be at a good 98 Fahrenheit but you skin will adjust to what's around you"
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7e6nc8 | how does a triangle have multiple centers? | The center of a circle or square is a point equidistant from all edges, so isn't the center of a triangle the point equidistant from all edges? | Mathematics | explainlikeimfive | {
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"There are several definitions of what the center should be. In a triangle, they don't end up at the same place. URL_0"
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7e6ot1 | Why do we have headaches when we are dehydrated? | Biology | explainlikeimfive | {
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"A dehydration may occur after sweating when the body loses essential fluids to function properly. ... When the body is dehydrated, the brain can temporarily contract or shrink from fluid loss. This mechanism causes the brain to pull away from the skull, causing pain and resulting in a dehydration headache. Taken from medicalnewstoday."
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7e6w24 | Why are my photos horrible and professional photos look amazing? I used to think it's because I don't have a nice professional camera but I've seen pro photos taken with a cell phone and they make mine look like garbage in comparison. What's the deal? | Technology | explainlikeimfive | {
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"First of all, by the time you see a pro's work, it's been through a lot of processing, like PhotoShop and the like. Cropping for the optimal composition, bumping colors up, enhancing clarity, etc, beyond what the camera itself is capable of. And it takes a lot of time to develop an eye for composition, that is, the best balance of objects in the image, how to make your subject stand out while de-emphasizing potential distractions. Should this subject be captured from a low, middle or high angle? Where's the light source and how is it going to affect the final image? Other variables are camera settings. ISO affects sharpness, but lower values increase exposure time, so can't be used for things in motion, unless you're intentionally going for a blurring effect. There are lots of other variables, but those are the ones off the top of my head. I'm not a pro, by the way. Maybe one will drop in and do a better job of explaining.",
"A better tool makes difference for the expert, not so much for the novice. What you see as quality is an understanding of composition, light, shadows and the limitations of the camera. The professional fotos are not \"Wow, cool, lets snap a shot of that!\", they are carefully planned. Some tips that will make you a better photographer: * Flash. Avoid flash if at all possible, it makes the photos look flat and washed out. If you need to use it, try to aim it at the ceiling or a wall, so you bounce the light. * You are a photographer, not a sniper. Don't aim directly at the subject, aim a little off. Usually, a good rule of thumb is to place the subject 1/3 of the image from either edge, vertical or horizontal. If you shoot a person in a landscape, don't have the person stand in the center of the picture looking at the camera. Place the person 1/3 to the side, looking sideways at the scenery, pretty close to the camera, and place the horizon 1/3 from either top or bottom edge. * Light. Photos live and die by light. In most cases, the ideal position of the main light is something like 45 degrees out over your shoulder. Sometimes you can play with light a bit, such as shooting a person with the full moon directly behind him, as a dramatic outline in the night, but usually, the light should be slightly from above and 45 degrees out. Smaller filler lights help reducing drastic shadows, but don't overdo it, or the foto will be flat and lifeless. * Understand the subject. For example, say that you want to shoot a vast desert landscape. Well, first of all, you may want to do a panoramic shot for that (AutoPano is great software for that). Then, think about what makes the desert so big, what makes you feel so small. Your gut instinct is to lower the camera so you get a lot of desert. Your gut instinct is wrong. It's the vast sky that makes it huge. Place the horizon 1/3 from the bottom of the image, and you get your vast desert landscape. * Don't be afraid to zoom. People often want to get as much as possible. Don't. Decide on what you want to shoot, and go for that. Say, for example, that you want to shoot a magnificient tropical sunset. Your instinct may be to zoom back to get all of it. Don't. Zoom in on the setting sun, with a palm tree in the foreground. Now, you get just the magnificient colors and the outline of the palm tree, and a much better shot. * Depth. If you shoot landscapes, have something/someone in the foreground to give depth (and remember the rule of 1/3) and to make it interesting. * Don't tell people that you are taking there picture. Unless they are professional models, it'll be awkward and unnatural. Just shoot when you get a good shot. Don't stalk people, though... * Shoot a lot. Pros shoot 1000s of pictures to get a few good ones. You'll probably have to shoot more... * Evaluate your photos. When you get a good one, look at it and think about what makes it good. What makes it different from the other photos that are bland and boring? * Tools. A good camera helps, but you can do a lot with a simple camera. I would advice against a phone, though, as they are a big mess of compromises, especially when there is low light (that tiny lens doesn't let much light in compared to a large camera). Get a simple camera and use that until you understand photography so well that you feel limited by it, then upgrade. Even if you later buy a SLR camera, you'll still often find that small camera useful, because the best camera is the one that you have with you. A very good book on the subject which I can recommend is Digital Art Photography for Dummies. Now, I really don't like the \"for Dummies\" series, but this one is good. It gives simple advice, and just reading it and keeping some simple things in mind will make you a better photographer. It sure helped me a lot. (Yeah, I know there are situations where these tips don't apply, but this is an ELI5, aimed at a beginner, so let's keep it simple. Following the rules until you understand them well enough to understand WHY you sometimes benefit from breaking them.)",
"In addition to what Erwin said, the Pros take a LOT of photos. In the days of the huge cameras with glass plates, a photographer like Ansel Adams or Robert Capa would take a few dozen to get the one good one that would be printed, that we look at in books today. In the modern day, with digital cameras and massive amounts of storage, with instant results, a pro might take a few hundred photos to get the one that goes in the magazine. It's a type of Survivor Bias.",
"lighting and composition. and i bet some degree of photoshop to smooth the image out a little bit.",
"I think ElMachoGrande said it the best. I used to take photography classes in high school back in the 70's. We had SLRs with multiple lenses and 3x5's. We developed our negatives and printed our images ourselves. Most of his recommendations are the same as we were taught because the principles of good photography never change. Like any art, it's mainly about learning from people who are gifted and whose work you admire. But there are some basic rules. Following them will help you to get better, faster. It's not about Photoshop, no matter what anyone says. Photoshop is just a tool to be used in post-production. The mastery of tools is not going to make you a photographer. Your *eye* and your perception is what makes you a photographer. You have to recognize an image's potential and be able to figure out how to make the most of it long before you ever get to post-production."
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7e6xzm | Submariners, from the point of view of the crew aboard. Once submerged, do subs ever experience "rough seas"? | Physics | explainlikeimfive | {
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"I was on an Ohio class sub ssbn from 2007 to 2011. The sub rarely rocked, even in crazy bad storms, below 400 ft. We steamed under a typhoon in the Pacific with no ill effects. Being on a sub underwater feels a lot like a big jetliner. However, very near or on the surface the boat rocks like a damned pendulum. Imagine a steel pipe with some weight on the bottom. Thats a submarine on the surface. It starts to roll like a round pipe and the only thing that keeps it up right is additional ballast near the bottom. But that also creates a weight that acts like a pendulum swinging the boat back and forth. Many sailors got sick a few times coming up to periscope depth. As for other stuff causing the boat to move, I could feel when the speed was changed by more than a bell turn (I.e. going from 1/3 go 2/3 ahead or more). I could also feel large rudder changes because they'd make the boat roll a little. The officer of the deck might sometimes order light angles on the boat, like a few degrees up or down, for various training purposes or to be a dick. I did it once to my captain. He told me he was going to go use the treadmill for an hour, I ordered a 3 degree up angle to make him work harder because I was passive aggressive. After 45 minutes he walked into Control and asked why there had been an up angle for 45 minutes. He didn't need to look, he could tell it by how much harder to run it was. I had to explain it was for \"training purposes\" so the helm, lee helm, and diving officer of the watch could learn as a team (it takes some coordination between those three to effectively keep the boat at an angle without changing depth). Anyway, we all laughed after the captain walked out. I'm sure the captain did the same thing when he was a junior officer. Edit: I got the idea from a more senior officer on the boat. We were not undermining the CO as someone said below. Submarines are different in that my CO was more like an older brother to me than a boss. I'm sure the CO laughed a little and months later after it happened with a different officer on watch he announced he'd no longer be telling us when he was running on the treadmill because, \"Sometimes I like to feel good about myself after a run.\"",
"Former Trident sailor here. I'd guess that 25% of the crew puked at some point, every patrol. It's noticeable. Sea sickness pills were common issue. The worst I ever saw was 35 degree rolls to *each side* (port and starboard) at 350ft (106.7m) deep, under a tropical storm in the Atlantic Ocean. So, yes-- on an Ohio class (\"Trident\") you can definitely feel the sea state, depending on the ocean conditions and the course of the submarine. I served aboard USS Kentucky (SSBN 737)(GOLD) and USS Alaska (SSBN 732)(BLUE).",
"I have not worked on a submarine but I was scuba diving once when a large earth quake happened. it sounded light a freight train was going over head but I didn't feel anything and we where maybe 40 feet down .",
"In stormy enough seas, you absolutely feel it. I was under a hurricane and even at 500 feet a lot of people got sea sick. I've never notice changes due to thermal layers or currents though. Sometimes the boat does 'Angles and Dangles', where the ship will perform maneuvers creating sustained positions that are fun (or frustrating if you are trying to sleep, cook, or do work).",
"Not a submariner but an aircraft carrier doesn't experience many weather effects either. When dodging a hurricane, we only had 5 degree rolls.",
"Yes. During a storm last year we felt rolls of up to 5 degrees to port/starboard and we were around 200m deep at the time. On the surface however you'd be getting thrown about as without a keel the submarine ends up corkscrewing it's way through the water, causes horrible sea sickness as there is no escape from it. (Current serving Royal Navy Submariner).",
"Former Sonar Technician on USS Santa Fe SSN 763 from 2010-2014. I remember tracking a civilian ship once, most likely a fishing vessel, when there was a very loud explosion. All of the monitors were blanked out for a few seconds and you could feel the explosion through the hull. It wasn't much, a brief shudder, but enough to know something abnormal had happened. Once the dust settled, so to speak, and the monitors resumed normal operation the fishing vessel was gone. Due to the area we were in there was no way to surface and investigate what had happened, or to send out a distress signal giving away our position. We all just assumed the poor souls were lost at sea and carried on.",
"It depends on depth. You'll never feel anything moving from one thermal layer to another. You'll never feel the currents. It's not like flying on an airplane.",
"I see a few fellow squids on here that we’re lucky not to have the issue. But serving on the SSBN-739 I can tell you during a hurricane we encountered some of the worst chain effects of seasickness over 50 people puking in funnels and buckets. You might be puking but you still stood your watch. On a side note you guys should be asking about the weirdest thing to have gone through the trash compacter.",
"Submarines don't have keels, so when surfaced you can feel the waves for sure. Below 200ft or so you can't feel anything.",
"If the events of 2012 the movie happened would a sub be safe?",
"My uncle served on submarines (US), and related a story where his (attack) sub performed search & rescue for a missing ship during a tropical storm or hurricane (near Charleston SC, back when subs were based out of there). The search required either a periscope or radar, and thus the sub was at relatively shallow depth. Uncle said that rolling to such a degree that the crew were lined up for the toilets, barf bags in hand, so bad was the seasickness.",
"Submariner here. SSN23. The answer is actually pretty simple. It is rare to feel the waves once your more than a few hundred feet down. The reason why is because of momentum. A submarine is always moving, except during very unique events. The main way of maintaining depth for a submarine is by using the stern and bow planes(mini wings on the side of the ship), and they only work when the ship is moving. A Submarine weighs many tons. Even a little speed is going to create a massive amount of kinetic force and you would need something of similar force to change it. Waves just don't typically come with that force unless you have a hurricane above and your captain feels like going full Ahab and going to PD. Now if your sub is trying to stay still, you will feel those waves, but that rarely happens.",
"I spent almost 5 years at sea aboard the USS Jefferson City. Never really pitched and rolled while at depth. Sometimes at periscope depth and snorkel depth we would experience rough seas. The boat really isn't designed to sit on the surface though, so when we weren't submerged she really rocked around a lot. The one time I ever got seasick was the night we were surfaced out in the harbor outside of Perth and the seas were so rough that we couldn't safely take on the harbor pilot to maneuver us to port, so we spent the night surfaced waiting for the sea to calm.",
"Another ex-submariner here. It depends on 3 things: the depth of the boat, the direction the boat is traveling relative to the waves, and your own personal sensitivity to motion. If you're deep enough, none of the other factors matter; the boat is as stable as land and you won't feel anything. If you're traveling in the same direction as the waves (or straight into them), you really won't feel anything. If you're traveling perpendicular to the waves, you'll feel them the most. The waves push the sail back and forth, but the rest of the boat is a tube that the waves just flow around. And everyone's sensitivity is different; not just from person to person but also day to day. I usually don't get seasick, but I have had a watch or two where staring at my panel and trying to do my job made me puke.",
"We went under HR Irene (1999) at a depth of 200 ft. You could feel it, but it was like being on the surface during a windy day.",
"I'm not a submariner and this doesn't really answer your question, but its a cool fact I learnt from an engineer that helps design subs. If you a tie a rope from one side to the other (port to starboard) so it's taught at sea level, when the sub dives, the rope will be on the floor.",
"The distance between waves is called “wavelength”. Wave motion can’t be felt at a depth equal to half the wavelength. If a submarine is near or below that depth, the submariner should feel little to nothing. Remember there’s a wide range of normal so some people may be more prone to seasickness than others. (These people tend to self-identify by carrying a bucket.) When you get older, google “wave base” for more info.",
"Served on a diesel electric sub in one of the Northern Europe countries way back. We had a lot of transport stretches (traveling to/from exercises) where we were not permitted to dive, and I can tell you that a sub on the surface in rough weather is horrible. The times where we were submerged, we still had to go up to periscope depth from time to time so that we could “snorkel”. Snorkeling is getting air from the surface through a type of “chimney”, so that you can run the diesel engine to charge the subs batteries. Trying to keep the sub on a constant depth of 16 meters in really rough seas makes it quite easy to keep awake during your watch, even when you have been in a 2h on, 4h off rotation for a week."
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7e72v2 | What happens to a nerve in your finger when it is cut and medical treatment is not performed? | Biology | explainlikeimfive | {
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"They grow back most of the time. Peripheral nerves can take a lot of damage and keep coming back. So long as some part of the axon or connective tissue remains, it'll grow back. If those things are destroyed though, it cannot grow back. This is much different from the central nervous system, which has a lot of trouble regenerating."
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7e73j6 | How pornstars avoid pregancies and STD's? Are there cases where they get pregnant and catch STD's? How they handle these? | Well, people dont normally discuss this with a 5-year old. But, i want to know it anyway, so enlighten me :) | Biology | explainlikeimfive | {
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"In the early days of the AIDS epidemic, it was a big deal, and many performers got sick. These days, they get tested very frequently. As for birth control, women use the pill and IUDs. And one of the career skills for a male porn star is being able to control ejaculation, so they will usually pull out before it happens.",
"In modernity they are tested often, sometimes weekly. In many sets they require the use of condoms. And they are all on birth control. Now that does not mean that pregnancies do not happen and that STDs do not slip through but they are relatively rare statistically speaking."
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7e7ca2 | Why does our left hand move in sync with our right hand and vice versa when we walk/run? | Biology | explainlikeimfive | {
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"It moves in sync with your body. Your right hand will swing forward with your left foot, and your left hand will swing forward with your right foot. This keeps your body's mass centred. Otherwise, your body would start to twist a little as you moved, making it harder to keep your balance or run in a straight line."
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7e7doa | How do butt/breast enhancement creams(or supplements) work? | I’m looking into buying a product that claims to lift your glutes, namely ‘Isosensual Curve.’ I’m guessing they the breast enhancement products that the brand has works in a similar fashion. | Biology | explainlikeimfive | {
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"They don't. Some of the creams make your skin feel tighter because it dries the skin out. Butt the reality is, it isn't doing anything other than making people feel more confident.",
"They don't work. It is all fake and at most they might make the skin feel tighter by drying it out (creams) or make you retain water slightly (pills). But for the most part they do nothing."
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7e7e0a | How do old TV shows change their Aspect Ratio to 16:9? | I was watching old Sitcoms and Cartoons, and noticed that alot of these have been 'converted' to the 16:9 aspect ratio. While their were originally shown in the 4:3 aspect ratio. The newer versions with the 16:9 aspect ratio don't look like they've been stretched or extremely cropped, but are still wider and have more background. How is this possible? | Technology | explainlikeimfive | {
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"They were originally filmed with widescreen cameras and cropped afterwards. However, these shows often had their photography planned for a 4:3 aspect ration, meaning they knew part of the image would be cropped out and thus didn't really care what was visible at the edges of the camera's field of view. This has caused issues where old shows being remastered in HD now have continuity errors or visible filming equipment in the corners of the screen because the studio rushed out the remaster without much quality control.",
"That largely depends on how the initial shows were shot. A lot of television dramas from the 90s, like ER or like X-Files, were shot on 35 mm film which usually has a default aspect ratio of 3:2 (which is larger than the aspect ratio of 4:3 that we consider to be full-screen). So while those dramas were broadcasted in 4:3 and even framed and directed as if it was 4:3, its source imagery is going to be 3:2 which can be easily converted in 16:9 for homevideo- or streaming-use."
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7e7iq0 | What determines what smells good vs what smells bad? | Recent exposure to the most foul smelling bathroom I have ever come across has made me question the reality of my senses. Are there people out there who think feces smell good and flowers bad? What determines our sense of smell? | Biology | explainlikeimfive | {
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"Not 100% sure on this so feel free to correct me, biologists: I think our noses sense chemical compounds that are in small particles that come off of objects. We have evolved to dislike certain smells because they are dangerous. In your example, faeces are dangerous because they’re waste product and often contain harmful bacteria. The bad smell helps keep us away. We like the smells of foods that have lots of calories because we need to eat to sustain ourselves. That’s my best effort at explaining, but I’m sure a trained biologist will be able to give you something more accurate/in depth.",
"Answer to your question is simple - mind. Now, why mind think that smell of different sulfuric chemicals are bad? Because most of them are poisonous. When organic matter rot it will release this sulfuric compounds in the air, and rotted organic is extremely poisonous. This create association \"smell sulfur - > poison - > need to warn human not to eat it - > mind send signal that it smell bad\""
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7e7xm8 | Why does copying a timestamped video from youtube result in URL_1 instead of URL_0 ? | Technology | explainlikeimfive | {
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"It's actually URL_2 . YouTube bought the domain URL_2 to make short URLs possible. This is actually no longer necessary, since services like Twitter (where short URLs were necessary) now use their own link-shortening services; but the option is still there. Basically, if you go to URL_0 , it simply redirects you to https://www.youtube.com/watch?v=xrCtMgKghW8?feature= URL_2 -- the \"feature=...\" part simply tells YouTube that you used the shortened link, so that YouTube can keep statistics. Quite simply, if you go to a YouTube video and click on \"Share\", it gives you the shorted URL. If you then click the \"Start at\" box, it adds the timestamp, giving you, for example, URL_0 ?t=1m30s -- which redirects you to URL_1"
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7e83ec | If computers are lightning-fast at running calculations and performing tasks, why does "freezing" take seconds or even minutes? | Technology | explainlikeimfive | {
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"Think of a computer as a train station. The computer manages the programs (trains) as they move about the station. There are always more trains than there are platforms and tracks, but the computer manages the trains carefully so each train gets time on a platform to do it's business. Now imagine one of the trains breaks down for some reason. Every train behind it is forced to stop and wait until the broken down train is fixed before it can move to the platform. If the broken down train is broken down in a way the computer can't easily fix, it sits there indefinitely.",
"Applications run on CPU threads. Single-threaded applications load everything on a single thread. You can think of threads as tasks. A single threaded app will do everything on its single thread. In this case, any long running operations will cause the UI to lock up and become unresponsive. This is because the thread is too busy attending to whatever work has been allocated to it in the background - it can't process UI interaction while this is busy. This is exactly why multi-threading is preferred for more complex applications. Multi-threaded applications move the background tasks that take a long time onto worker threads that work independently and (mostly) asynchronously from the UI thread. This frees up the UI thread to process user input and report progress of any active tasks that might be running in the background. Source: I'm a professional software developer.",
"If you send computer into infinite calculations - it's really don't matter if he is slow or fast. He will be calculating it forever). Like: While (TRUE) do I=I+1. It's freeze because of code bug. Or let's say there may be semaphore lock. Process A need resources X and Y to complete his job. He will lock resource X, but Y is already locked for process B, so A will wait until Y is released. In mean time process B will require resource X to complete his calculations (and he will release resource Y after it). But X is already locked by process A. So we ended in double lock, that will freeze your system forever. (Or until operation system will interfere and kill both A and B ))) And it's freeze because of resources allocation. All this freezes are independent from CPU speed."
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7e86rd | Why do we remove starch by soaking potatoes in order to make crispy fries but coat chicken in starch for super crispy fried chicken? | Chemistry | explainlikeimfive | {
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"This is research I've done just now, but... from what I understand, you're not actually removing starch from the potatoes, but rather altering the structure. The reason starch gets crispy during the deep-frying process is because it boils water out of the outer layers of the food, leaving behind a porous and brittle structure that can fracture - crispyness. Water helps space out the starch molecules by soaking in between them, and when it subsequently boils away during the deep frying process, it leaves a nice crispy structure. This is why a batter is going to be much more pleasantly crispy than something simply coated in flour."
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7e89oj | In the case of muscular injuries - why does it hurt more 24-48 hours after, than at the point of injury? | Biology | explainlikeimfive | {
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"I know the moderators would prefer we give a detailed explanation, but the real answer is that we just don't know. What you're describing is called \"Delayed Onset Muscle Soreness\". There have been some theories as to what may cause it: We used to think it was caused by lactic acid build up, but that is no longer believed to be true. There is a theory that it may be caused by excess calcium in the cells but I'm not sure that has been proven to be true either. Inflammation is thought to be involved (turmeric actually helps to prevents DOMS) but the exact mechanism is unknown at this time."
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7e8f61 | why does ALT CTRL DEL sometimes fail? | Technology | explainlikeimfive | {
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"A computer and all the things connected to it are managed by the operating system. When you're running a program that uses a keyboard, the operating system works as a translator of sorts that receives the button presses from a keyboard and then forwards that onto the program you're running. When you press Ctrl+Alt+Del at once, your operating system triggers a special response that attempts to pause all other running programs, start the task manager, and switch to it. When it fails, that means that this process got messed up in some way. The process of pausing the other programs is called a \"context switch.\" Basically what happens is the OS makes a quick backup of the current state of the program and moves all of the currently running code out of the processor and into the RAM. In order to do this though, the OS has to first ask the running program to get to a point where it can be saved as a state. If the program is stuck (in a loop), it will not respond to the operating system's request to pause. So ultimately the operating system is dependent on the currently running program being able to pause itself, which it can't do if it is stuck for any reason. When it's stuck, then the OS has to go through some more complex recovery routines that take a while and will cause slower computers to freeze."
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7e8lpu | How does Japanese multiplication work? Why does this work? | For those who don't know it is a system of counting the number of times a line intersects | Mathematics | explainlikeimfive | {
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"It's literally the standard, basic long-form multiplication algorithm, except you're drawing lines rather than just multiplying. Check out [this example]( URL_0 ) If we were do to this the old fashioned way, we'd do: 23 x12 --- 46 +23 ---- 276 And, notice, in the image that's exactly what we have: 2 intersections all the way on the left. 4 and 3 intersections in the middle (which we add) and 6 intersections all the way on the right. Intersections = multiplication because each line is crossing each other line. Each line creates that many intersections for each other line it crosses. This is simply repeated addition which is what multiplication is."
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7e8o5m | how do some areas have more than one power supplier since I would assume they would be using the same power lines and infrastructure? | Other | explainlikeimfive | {
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"There are a number of ways thus can be done, but in general the model breaks the system up into different parts. The first part produces electricity. There are numerous power suppliers, e.g. dam operators, coal plant operators, nuclear plant operators, etc. These power generators sell their output to various distributors who are the second part of the system. People then buy their power from these distributors who are paying the producers to generate electricity. All the electricity produced within a region by the generators then gets put into the electricity pool or grid. There is a third part of the system that handles transferring generated electricity to the consumer. They own the wires, transformers, etc. They charge the distributor a fee to use their equipment to sell it to the end user. So there are a bunch of different producers generating power, a bunch of distributors buying power from generators and selling it to consumers but usually only one grid operator that delivers electricity from the producer to the consumer."
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7e906r | If Forbes says a person is "worth" $1bn, how does that translate in terms of that person's bank balance? Do they have $1bn to spend? | URL_0 This guy is said to be worth $1.1bn. Can he use said "worth" to go buy a yacht or a plane. Or does this not translate as monetary gain? | Economics | explainlikeimfive | {
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"No. It’s in assets. Most people do not have their money in spendable currency, but rather in investments and property. The other term most people throw around when it comes to finance is the term “liquid”. This is the actual amount of their wealth that they have “liquidated” to spend.",
"It means if someone sold everything they owned and got market value for it, that is how much money they would get for it. For example, a 50-year-old professional might have a net worth over a million dollars. But since most of that wealth is going to be tied up in home equity and retirement funds, they aren't going to be doing a lot of jet-setting, they likely will be living a comfortable middle-class lifestyle.",
"a net worth is your assets minutes your liabilities. your assets are the things you own. check and savings accounts, cash, cars, house, retirement accounts, investments, royalty contracts, etc etc. things that are or can be turned into cash. your liabilities are the things that you owe. mortgages, loans, alimony, child care payments. just because i'm worth $1mil doesn't mean I can go out and spend $1mil. cause...that's all i'm worth. i'd have to liquidate EVERYTHING i own to come up with $1mil.",
"No, they don't have 1.1bn in cash. What it means in terms of worth is their cash *and* their assets. So they might have 100mn in cash, a company valued at 800mn, and a 200mn dollar home for a total value of 1.1bn. This is actually sometimes a problem for uber wealthy people called being \"cash poor.\" If all or most of your wealth is tied up in assets, if those assets suddenly depreciate in value you stand to lose a big chunk of their wealth, more than if they had the same amount in cash. If, for example, I'm a mid level executive at Enron and I've invested a large chunk of my money in Enron stock, when Enron collapses my stocks are worthless and I've lost all my money that I've invested into the company."
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7e975d | why the value of so many western currencies is roughly equal? | USD, EUR, CHF, GBP, AUD, CAD, are more or less aligned to a 1:1 ratio, when I don't think there is any economic/financial reason why they should be so. Is it just the result of a convenient choice? | Economics | explainlikeimfive | {
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"Many of these currencies are or were pegged to the USD after WWII. Since the United States had the vast majority of the world's gold (lend-lease was expensive, as it turns out), the agreement was that the USD would be backed by gold and the other currencies would be backed by the Dollar. (The [Bretton Woods]( URL_0 ) system) In fact, France and Switzerland actually followed through on this, redeeming their reserve USD for around $250 million in gold in the late 60's. This of course prompted Nixon to make the Dollar free floating, backed by nothing in particular. (The Nixon Shock) Since the Euro and Australian Dollar were created after this system, it made sense to value them around 1:1 with the USD. The Pound Sterling and the Swiss Franc were initially valued at around 4:1 with the dollar, but the post war economic boom in America rapidly increased the relative value if American dollars, bringing them more in line with each other. The Canadian dollar, on the other hand, was pegged at 1.1:1 in the 40s and has been slightly less valuable ever since. TL;DR: America had all the gold after WWII and made the rules.",
"That's a great question! I'm sure someone else can give a more complete answer, but it's in part due to the fact that several of these western countries had explicit currency pegs tying their currency to the price of gold at similar rates (so, you could covert dollars to gold at a fixed rate the government set) - read about the Bretton Woods system for more info about that: URL_0 . For a time several countries also explicitly tied their exchange rates to the US dollar (so, you could exchange that currency for US dollars at fixed rates). This kept the exchange rates relatively stable, and many of these countries chose pegs that were near a 1:1 ratio. Today, those countries you listed don't have explicit pegs, but the central banks operate in similar ways. Many central banks of developed western countries either formally or informally manage their policies in order to hit an inflation target of around 1-2%. This and the fact that the currencies had similar initial values due to the choice of the previously fixed rates keeps the exchange rates fairly stable as the different central banks have similar goals."
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7e9slo | Why can't we harvest blood from a dead person like we do organs? | Biology | explainlikeimfive | {
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"It's impractical. Blood coagulates quickly and most of the situations where the person is ideal for organ transplant (e.g. young and healthy) are situations where the person dies of some sort of trauma, which of course usually leads to large amounts of blood loss.",
"While a person is alive blood donation is possible due to the pumping of the heart. Hooking up a person to an artificial heart for the purpose of retrieving blood is not feasible.",
"Ok, I've been working in the blood transfusion industry for almost five years, so I may have some context that other people don't. My understanding is based on NHSBT guidelines (which tent to relate to EU guidelines), so the US or Australia might have different priorities. I am also assuming you're meaning whole blood donation. First things first, patient safety. If a person dies in a manner whereby they are able to donate organs, it is typically a traumatic injury. If the donor died before receiving medical attention, the blood is likely to be contaminated with bacteria from outside (that a non-functional immune system will not be able to limit), or the release of dangerous substances from within the body into the bloodstream (which could have limited effect on organs *in situ* as blood isn't circulating) but could cause a problem to the patient. Additionally, the donor, because they are dead, cannot be questioned about potential health issues (recent potential exposure to malaria or west nile virus, for example). On the other hand if the donor had been receiving medical care before death, then their circulatory system is likely to be loaded with pharmaceutical compounds (anticoagulants, painkillers, antibiotics etc.) which could have dire consequences for the patient receiving the transfusion. Secondly, Informed Consent. I'll sidestep this issue by making the assumption that the deceased who would be donating in this scenario have actively agreed to this situation beforehand, similarly to people joining the Organ Donation Register. Thirdly, practical measures: In order to extract a reasonable amount of blood from a donor, something similar to a cardiopulmanory bypass machine would need to be used. These necessitate the use of anticoagulants (otherwise the blood clots in the machine) which could have an effect on the patient.^(1) This would be an extra bit of machinery, with an extra operator (or two) in an already high pressure situation of an organ transplantation. Also, due to the drop in temperature associated with death, the whole blood begins to degrade (noted changes in potassium concentrations and protein levels in particular). As a point of praxis I return to my point about potentially having no recent information about the donor's health level, or access to their Doctor in case of issues. This would necessitate a huge amount of extra testing for each unit of obtained blood.^(2) Lastly: We're not short of blood, we're short of donors. What we need isn't 10 units from someone all at once, what we need is to replace the person who can no longer donate for medical reasons, or because of a change in lifestyle. What we need is a more diverse group of donors, so that people from ethnic communities can find better immunological matches. What we need is somebody who will walk into a donor centre every 12-16 weeks and give half an hour of their time to save and improve the lives of hundreds of thousands of people a year. 1) There is a technique for extracting blood components in a similar way to this from living donors, called Apheresis. It is used commonly to allow donors to donate specific components (for us largely plasma and platelets) more frequently than is safe for whole blood. It does rely on the donor having a working heart, and does use a lot of clever mechanics to reduce the amount of anticoagulant needed. 2) We in NHSBT recently began testing donated blood for Hepatitis E. This caused some interesting supply chain issues, and could have impacted the suppl;y of blood to hospitals, as well as making it more expensive and less efficient to process (extra testing machinery, extra reagents, extra running time for tests).",
"Why would we need to? Blood is cheap and relatively plentiful - there is not a shortage for it as there is for organs. I suspect the answer is economic - it's not worth the effort.",
"Cultural taboo and the fact that there are living people who are willing to give their blood away for free. Cadaveric blood transfusion has been carried out successfully in the past. Infection is not the leading cause of mortality among Americans anyways, so concerns about recently deceased people not being safe sources is not really valid.",
"We can, its just expensive and impractical. It's a lot easier and safer to get blood from living people. All things being equal, you would prefer to get blood from someone young and healthy. That's why there is an endless list of exclusions they go over when you donate blood."
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7e9xdo | Approximately how wide is Earth’s “orbit zone” and why is this the case? | Not really sure what else to call it, but if we’re sending a satellite into orbit or something, how much room for error is there? Does it all depend on velocity? Is there a thin strip of area that satellite needs to stay within or can it be within like three football fields? OR, is there no such thing as an “orbit zone” and theoretically a toaster could orbit our planet if it was ten feet off the ground but traveling at super speed? Is there an equation for this? TLDR; Someone please explain how orbit works. | Physics | explainlikeimfive | {
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"You just need to move an object fast enough that the centrifugal force counteracts the gravitational force. I don't know if you are familiar with free body diagrams, but you point the gravity vector downward to the earth, and then accelerate it sideways (put an arrow sideways). if you go sideways fast enough you won't fall. Its just like tying something to a string and swinging it, so yes theoretically a toaster could orbit our planet if it was 10 feet off the ground, really fast, and immune to hitting things (including air) that would slow it down.",
"In the simplest sense: you can orbit at any altitude, it's just a matter of attaining the proper velocity. Remember that orbits don't have to be circles, either, just ellipses. So you've got plenty of options. Slightly more complex: if you want anything like a stable orbit, you'll want to get out of the atmosphere, because the drag will slow you down an eventually make you crash. Very complex: other than drag, the other major influence on orbits is the gravity of everything else in the solar system, most significantly, the sun and the moon. You'll need to account for those eventually, but it's not simple.",
"If you want equations just go to the [wiki page on orbital mechanics]( URL_0 ) , and you can see that an orbit is technically possible at any altitude or eccentricity with corresponding velocities (the closer to the central body you are the faster you are/have to be). Then again, if you are at orbital velocities you can't actually be within the atmosphere below 200km because the friction with/compression of air due to the high velocity will slow the satellite down relatively rapidly, or burn it up like a meteor if below 100km. Also, if you get close to other celestial bodies you will find that their gravitational influence will change your orbit, or if that influence dominates/becomes larger you will start orbiting that body. Earth's influence dominates any other for ~900 000km unless you are within ~70 000km of the Moon. So you can have a satellite orbit Earth anywhere between 200km and 900 000km distance from Earth in any ellipse that fits within that sphere which is quite a wide room 'for error'. The actual problem is getting satellites into an orbit that is useful, so relatively low orbits for earth observation, or geostationary orbits at an altitude around 37 000km, or synchronized, elliptical orbits so the satellite stays above a certain area for a relatively long time."
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7e9xx3 | How come when we close one eye, we see “nothing” out of that eye, but when we close both, we see black? | And when I say nothing I mean that you don’t see black, just...nothing. | Biology | explainlikeimfive | {
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"You see the black, your brain just chooses to ignore it because it's useless information. It concentrates on the things that it can see."
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7ea8ea | Why do older video games look so angular, like they were pasting faces on the blocks of wood? What changed? | Technology | explainlikeimfive | {
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"Computers do 3D graphics with angular, pointy shaped polygons. If you wanna make something look smooth and rounded, you need to use **more** little polygons to approximate a rounded edge. Problem is, more polygons means more resources for a computer to keep track of, and on older systems eventually you'd run out of memory to keep track of it all. So in ye olden days, you had to look for stuff you could skip drawing in 3D, and paste a picture on instead. Pasting a picture on aka \"using a texture\" could be less \"expensive\" for the computer to spend time on rather than really building details in 3D. So a lot of facial detail (how eyes are set in, how cheeks are rounded) would get skipped over. [Here's a kinda long video showing off Mario's evolution over the years.]( URL_0 ) In his N64 days, it took 752 polygons to make his shape, but by the time you get to modern models, it takes over 10,000. But in exchange you get to model all sorts of little details (like his mustache! And fingers!) that help him look way better. The N64 simply didn't have enough memory to store this, and even if it did it's CPU was too slow to draw it fast enough: ideally games need to draw a new picture of what's happening on screen **at least** 30 times a second in order for the motion to look okay.",
"They are still using blocks of wood, but nowadays computers can handle bazillions of blocks at once so each one can be microscopic.",
"back when these games were made, computers were far less powerful than they are today. as such, games were designed to work with whatever hardware was available at the time, meaning that things in the game had to be made as simple as possible so that it would run properly on the average consumer machine. The qualities you're describing, such as everything being angular, is an example of that simplification.",
"That's actually a fairly accurate comparison. Game consoles were very limited up until around the Gamecube/PS2/XBox era where 3D graphics were advanced enough to actually model a character's face. Compare it to Mario (Jumpman. w/e) in Donkey Kong, to Mario in Mario World. I Donkey Kong He doesn't have a mouth, or eyes, or many distingusing features. Then as technology improved, his' body can be better drawn because the console supports higher fidelity sprites.",
"They looked so angular because they were using computing hardware which was much less capable. In order to create the minimum 3D object you need at least 3 points, and connecting them together forms a 2D triangle located in 3D space. These triangles can be connected together to form a 3D model, and more triangles mean the model can become more detailed. When an image is \"rendered\" the computer needs to process the locations of all those triangles and how their surfaces would look from a particular direction. For a complex scene this can mean an extremely large number of calculations which need to be performed very quickly. Older games were designed so their number of triangles could be processed 30 times a second which resulted in blocky models. These days we can process a lot more so you probably can't tell they are made up of those same triangle shapes."
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7eaatt | How do air breathing sea animals like dolphins or whales not drown during violent seastorms? | Biology | explainlikeimfive | {
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"I think you're greatly underestimating how comfortable marine mammals are in the ocean. They're literally in their element. They pop up and take a breath, no big deal. If you've ever seen seals in a high surf zone, they just bob & float with not a care in the world, and duck underwater at the right time to avoid injury. And *that's* near a rocky coast, a far more dangerous environment than the open ocean. For one, marine mammals are flexible, compared to the rigid hull of a ship which is prone to breakage. For another, they're small & nimble compared to aircraft carriers & tankers. Surfacing during huge swells would feel more akin to an amusing ride than a life-threatening scenario. They're also made to be *in* the water, not on top of the water. Trying to keep an open canoe afloat in rough weather would be a harrowing experience. But simply floating an incredibly buoyant body near the surface? No challenge whatsoever. Marine mammals are incredibly well-designed for taking quick gulps of air, and in large seas it's easy to time breaths so they don't take in gulps of water. Finally, I'll add that all marine creatures are by definition fine-tuned to ocean living. Even experienced humans (surfers, for example) can feel inertial changes underwater and sense when wave crests are approaching. Marine mammals' ability to read water far outstrips ours, as you can imagine, which would give them further ability to withstand, even enjoy, large seas. At sea you can often see dolphins surfing the swells, and I wouldn't be surprised if they used large storms to their benefit, traveling long distances with minimal effort.",
"the more violent the storm, the larger the waves. the larger the waves, the longer the time between waves. an air breathing mammal would have plenty of time to grab a breath in a large wave trough. Not to mention - whales and dolphins can leap from the water. Not sure if they are able to grab a breath while doing so or not. Edit: Don't forget - some of these critters can hold their breath for 30 minutes or more. If you only need a couple breaths an hour, what are the chances of that violent storm just sticking around long enough to even be a challenge?",
"Whale Watching Captain/Naturalist here. Cetaceans exhale most of their lung contents AND inhale in less than a second. Even while they are breathing \"normally,\" they hold their breath between ten and thirty seconds. After a handful of breaths they often \"sound\" (diving deeper, and for an extended period of time- anywhere from 5 to 90 minutes depending on species). For developed adults, a storm would be well within their comfort zone. However, a storm would very likely present a threat to newborns and perhaps very young individuals. This is believed to be part of why some species (though not all) migrate to calm, warm, and protected waters during their respective winter months (when storms are most prevalent). I URL_0 answer helps :)",
"The surface of the ocean away from land during a large storm isn't full of breakers - it's just rolling wave after rolling wave. The waves can get quite large, but keep in mind that the animal is mostly under the water. It can surface on the back of the wave and ride the wave down to the bottom of the trough and breath that entire time, and then just submerge and the bottom of the trough. it takes a little bit more timing than on a calm surface, but otherwise is basically the same operation.",
".....So apparently I made it 30 years without knowing Whales and Dolphins breathe air. What are you telling me right now? I know they have blow holes but I never once thought they used it to breathe. I just thought it was somehow related to food. Like they eat something and the stuff they don't eat they blow out through the hole. Fucking damnit I'm stupid",
"I don’t know the answer to the question, but I had a neat experience kind of related. I used to work on oceanography research vessels and once while off the coast of California, approx 400 Miles west of point conception we were in 40-50 foot sustained seas. I read another response on here that said open ocean swells don’t break - this is not true, they absolutely break and it is terrifying. My particular lab could not do our research in these conditions, so I would stand on deck for hours and marvel at the power of the ocean. The ocean when it gets crazy, feels dreamy to me, like the waves are surreal in their power and magnitude. Holy shit I just got the chills thinking about this. Anyway, I was standing on deck and saw a momma blue whale and her calf riding 50 ft swells. They were just nonchalantly traveling through the ocean at like 15 knots or something absurd. Marine mammals live in the ocean and are well adapted to their environment.",
"1. Different sized bodies experience waves differently. To toss an aircraft carrier around, the waves have to be very large. Those large waves mean a smaller body, like a dolphin, will experience that huge wave as a (relatively) flat area. This is relatively non-intuitive, but give it some thought, and maybe do some experiments with a rubber duck in ocean waves. 2. Most storms move between [10 and 30 mph]( URL_0 ). This means the really turbulent areas can be avoided by moving around the storm. Human ships tend to be on timetables, which constrain them from avoiding storms. Dolphins are more free to avoid the storm's path. 3. Dolphins don't have any sort of water-catching system to prevent breathing in water. They have powerful diaphrams, and can completely exhale, then inhale, in under a second. So they depend on having their blowhole completely clear while they breath.",
"Here's a dumb question: Why would mammals that live in the water not evolve the ability to breath underwater? It would be a selective advantage, it seems like. Maybe the oxygen requirements of large brains are such that gills won't provide enough? I realize it also sounds silly but given that more than one mammal actually lays eggs, gills don't seem so crazy. The eye of the duck-billed platypus is supposed to be closer to the eye of, of all things, the hagfish than to the eyes of other mammals which also sounds as crazy as gills would be."
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7eajja | Why do we not feel food go down our bodies? | Biology | explainlikeimfive | {
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"You don't have touch receptors in your gastrointestinal tract. You can sense pressure and things gurgling around because of that, but not actual touch."
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7eawa8 | I'm getting my first glasses at the age of 27, what are some things i should do/know? | Other | explainlikeimfive | {
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"It will be disorienting for the first couple of days. Try your best to ignore this and keep the glasses on. You may get some headaches - this is due to your eyes adjusting to your glasses. Other than that, you will be amazed at how much you were missing!"
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7ebdxw | Why do fridges pop and bang (very loudly) | Technology | explainlikeimfive | {
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"Cracks, pops and bangs (especially rare, kinda unpredictable ones) may be your ice maker. Ice forms in a mold and eventually gets ejected, often shattering in the process, then tumbling down onto it's cubey brethren. More \"mechanical\" noises might be the compressor.",
"It's likely the defrost cycle. Refrigerators work with a liquid (refrigerant) that gets compressed by the compressor then allowed to expand inside some tubes. That expansion absorbs heat from inside the ice box, making the area cold. Unfortunately, a limitation of the refrigerant is this process happens at only a pretty cold temperature, about that of freezing ice. So because of that the moisture in the air of the ice box gets frozen on the coils inside. So ironically, there's a heater in there that melts the ice off the coils every hour or two. It's called a defroster. As that ice melts and heats up, sometimes it cracks and breaks, dropping into a drip tray. That's the sound you're hearing. :)"
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7ec4nj | Where do the bubbles come from when boiling water? | Physics | explainlikeimfive | {
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"Two places. The tiny bubble you get before it starts really boiling are air bubbles. Air dissolves in the water, but as the water heats up, it can't hold as much air, so some of it will form bubbles as it leaves the water. Second, the bottom of the pan is the hottest, so the water on the bottom changes to a gas before any other water does. It forms bubbles that float to the surface.",
"Water evaporates (=turns from liquid to gas) when it reaches boiling temperature. The first part of your kettle to reach that temperature would usually be on the bottom (or wherever the heater is located), so the water around the bottom turns into bubbles of evaporated water which rise toward the surface."
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7ec6ps | How a music video is shot in slow motion, but the singer’s lips are synced with the audio | Other | explainlikeimfive | {
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"Increase the song tempo, have artist lip sync, slow video. Words will be at correct speed, everything else will move in slow motion. It's a really cool effect, and not to hard to do, just some math to calculate the BPM's.",
"They speed up the music, and then shoot it at normal speed where the singer is singing faster along with the music. Then when they slow it down, it looks normal speed but everything else is faster."
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7ec6yu | why is math (statistics, calculus, etc) so important for a strong programmer? | Mathematics | explainlikeimfive | {
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"There are lots of areas of programming that require only basic math. If you're doing development for a moderate-sized web site or app, it's quite possible you'll almost never use any math, and never anything beyond things taught in high-school algebra. More generally, some programmers use a lot of math all the time, some hardly use math at all. There are many more specialized areas of programming that require a lot of math. Computer graphics uses a lot of trigonometry and calculus, so pretty much any game that requires physics or 3-d rendering uses a lot of math. Video and audio compression uses Fourier analysis. Cryptography uses number theory. Those are just a few examples - there are lots of specialties. Good programmers often need to have at least some familiarity with those areas, even if that isn't their area of expertise. Quite often large-scale software engineering requires more math - for example web sites that need to scale to millions of users. It's hard to properly optimize sites to handle a lot of traffic without a good foundation in probability and statistics. A degree in Computer Science typically covers many of those things, which is why there's a math requirement. In addition, Computer Science involves a lot of mathematical analysis of programs, including determining what's possible to compute, determining asymptotic runtime and memory usage, and mathematical proofs of bounds and of correctness.",
"Programming is - in a sense - just applied math. Math has a strong emphasis on: - logic - developing/applying algorithms - defining stuff (classes, groups, etc) I'm not saying you can't become a great programmer without studying maths, I'm just saying since they share so many similarities it usually helps to learn both or that it is easier for you to learn the other if you find you have a talent for one of them.",
"Both math and programming are strongly based in logic, so there is going to be a lot of skill overlap. Writing a program is often very similar to constructing a mathematical proof. You need to create steps that both logically flow together, and that are valid in the general case, not just in special cases. The skills behind math often apply to programming in a sort of a vague way. I might not ever need to find the integral for a hyperbolic trig function, but the mode of thinking that let me do that often also apply to math. Computers are often doing tasks that require higher level math to fully understand. If I am using a random number generator to perform a simulation, I had best understand probability and statistics to ensure the results are valid. I had also best have a little number theory so I understand how the RNG works. If I want to analyze how long that program will run for a given input and how much space it will require, that brings in abstract algebra, number theory, and calculus. Also, computers are often used to directly solve math problems. If I need to invert a matrix or find an approximate solution to a complex equation, I need enough math to understand exactly what those things mean. Finally, you never know what math you are going to need, so it is good to have a big toolbox. I learned what a Poisson distribution was in college, thinking I would never use it. More than a decade later it was the key to diagnosing a serious network problem.",
"It's not really, for most types of programming. 90% of programming tasks are writing (hopefully) straightforward logic, like, if user_clicked_resume_button(), then close_menu_and_resume_game() Logic like this is considered 'math' by mathematicians, but isn't normally what you and I would consider math (like calculus). **Statistics probably won't be useful** to a programmer unless that programmer is writing a program that must analyze a bunch of data - e.g. some research professor is doing a study which has a large amount of raw data, and she needs to draw conclusions by finding statistical patterns in the data - which the computer can be programmed to find (usually the programmer is just translating the professor's math formula into computer code, which often isn't too hard). **Calculus isn't useful** in everyday programming either, unless your program needs to do specifically do something with calculus - like calculate the volume of a 3D object. It's useful if you're doing very lowlevel graphics processing - or, say, writing a program to help students calculate a calculus equation. **Addition and subtraction are used** a lot in programming, but again, usually only when the program needs to tally something. (Low-level computer operations may require +-*/ operations to implement algorithms to find new memory locations from old ones, e.g. if making a custom data layout in C++ - but again, programmers are doing these explicit low-level manipulations with math less and less because all this stuff is already done in libraries they include.) **All kinds of math could be used in programming to _optimize_** the speed of your logic (algorithm) by doing fewer operations to achieve the same result - but if you really need that kind of optimization, you're probably going to get the algorithm from a textbook written by a really smart dude, like Knuth. Even if you're doing a math-intensive task, like graphics - in today's world, you're not likely going to implement the math part of a rotation, you're going to call the rotation() function in a well-tested library. tl;dr **Unless you're making software that is specifically made to do mathematics/simulations/data-analysis, then you're not going to need much math.** A programmer would need to know a lot about gardening if most computer programs were all about veggies.",
"Because programming is math. It's the distillation of a real world process into a set and predictable series of steps, ie, an equation.",
"Realistically speaking, most programmers never touch math except to increment counters. Maybe there's some basic addition/multiplication/division occasionally. To take a step back, most computer programs consist of a series of steps that need to happen more or less in order. If you can't break things down into steps all the math in the world isn't going to help you program. That's probably where the \"strong at math\" part comes in, because that's an obvious indicator that someone is good at deconstructing a problem. There are other indicators of good programmers which aren't so obvious, like system-oriented thinking and algorithmic thinking. Those are a lot more difficult to describe and spot. If you want a \"real\" programming skill, learn how to make a recipe then walk someone through it.",
"Programming is a form of applied mathematics. A better understanding of the underpinnings can aid in their application. Set theory, group theory, and category theory are underpinnings of computer science, and many white papers on computation and computability are described in these terms. Mathematical analysis is used heavily to measure properties of programs, typically focusing around efficiency and complexity. Lambda calculus is a formal system that describes computation. There are many other branches and systems of math that can be used to describe different aspects of computation itself. It's not all just applied mathematics in terms of using X mathematics to solve a business problem. Knowing statistics, for example, would make a programmer very valuable at measuring performance, efficiency, and correctness of programs, and is typically an obtainable skillset to most developers. You don't necessarily need explicit knowledge of maths to be a developer. Lord knows, I've worked with mouth breathers who managed to do enough to not get fired. Kudos to them. Also a consideration is there's plenty of software that can afford to be incredibly wasteful, which is actually most software.",
"So there's a lot of different kind of \"programmers.\" It's a big field. Some people focus on front-end development like making websites and interfaces. Turns out, a lot of UI programming is math-based. Animations or \"tweening\" (moving from A - > B) usually use basic quadratic, cubic, or sinusoidal equations to simulate speed. Anchoring parts of the UI so that the window reacts well when you change the screen size is another example that uses simple math principles to very complex effect. A lot of this kind of programming has been abstracted away, however. But a more fundamental answer: computers, as we know them, are math machines themselves. You've probably heard that \"everything to a computer is 1's and 0's\" before, which is true. Everything you see and do _does_ eventually become a 1 or 0. This has implications for what we can do _with_ computers. Alan Turing famously came up with the concept of a Turing Machine, a theoretical contraption that can compute things for us. From there, we can reason why, for example, it's impossible to invent a \"perfect antivirus\" that can always detect whether a program is a virus or not. It also proves (mathematically) that we cannot generally analyze a program and say, \"will it terminate, or loop and freeze?\" (i.e., \"will this work?\"). And on the back-end of things, you generally have to deal with data and things *at scale*. Let's say, for example, I have a system for storing and retrieving customer reviews. If I have only ~100 customers, I could probably save them however I like (maybe I stuff them all in a folder with the date as the file name). If I then need to find a specific review, I _could_ just open them all up one by one until I find the one I'm looking for. Now imagine if I'm storing millions or billions of reviews. Time complexity (how long does it take to do what I want?) and space complexity (how much _actual space_ do I require--RAM/Harddrive--to do what I want?) are fundamental concepts to understand for any modern computer scientist or programmer. Because small problems can suddenly balloon into very large ones if we're not careful. Understanding how complex these kinds of problems are directly relates to math. This gets into P and NP--namely whether something requires a polynomial- or nondeterministic polynomial-time algorithm to solve. But that's a much more detailed subject. Put another way: If you've heard of the [traveling salesperson problem]( URL_0 ), we know from complexity theory that we can't build a program that will do the following: Given any graph (map), we can find the shortest path that will visit every node (location). It's just too complex and the problem becomes too large for larger inputs (i.e. big maps and many locations). Of course, if you use Google Maps, you're probably thinking that of course we can solve that problem, Google does it super effectively. Truth is, people come up with very clever algorithms that can very closely approximate answers to these problems. EDIT: **WHY THIS IS SO IMPORTANT FOR A STRONG PROGRAMMER:** A lot of these super high level and super low level concepts aren't used in all your programming. However, they inform a strong programmer's intuition, and they can be used to \"sniff out\" bad code and design. It's kind of like having a strong minimap and radar in a game: It might not tell you exactly what's out there and where to go, but it makes it damn easier to figure it out (and easier to correct course if needed)."
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7eck14 | what physically changes in a computer when you save something? | If you were to look through microscope what is the physical change you would see in the components? | Technology | explainlikeimfive | {
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"It depends on what type of computer. If it is a conventional hard drive, or mechanical drive, with the right instruments you would be able to 'see' microscopic magnetic pits on the surface of the disk change from off to on. The mechanical drive is a magnetic storage device. Depending on what areas are on or off tells the device and thus the computer what is written there. If your talking a Solid State drive (SSD), or the type of chip memory in phones the storage of data is written into the memory in a different way. As far as I know, there is not a physical change that you could see from the outside."
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7eckbt | Why do you sometimes have to use the bathroom immediately after you eat or drink even if you didn’t need to before? | Biology | explainlikeimfive | {
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"To make room for what you're just after consuming. (This may sound like a joke, but it's actually fairly accurate.)"
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7ecl5u | If temperature is defined by the movement or jiggling of particles like atoms and molecules and if a vacuum is defined by an absent of those particles. How can a vacuum have a temperature? | Physics | explainlikeimfive | {
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"> If temperature is defined by the movement or jiggling of particles like atoms and molecules... This actually quite isn't true; it's just a useful rule of thumb that the layman can understand. The actual value of temperature is dependent on the relationship between energy (which, loosely, is the same thing as the jiggling you mention) and entropy (which is...more complicated). For the temperature and pressure ranges where we live, the \"jiggling\" assumption doesn't have that much error associated with it, but when you get into more esoteric environments the error increases significantly (mainly due to the fact that entropy is weird). An interesting result of this is that the entire idea of the Planck Temperature is inherently wrong; the upper limit on temperature is not 1.417x10^32 K, but is actually -0 K. > and if a vacuum is defined by an absent of those particles. How can a vacuum have a temperature? A *true* vacuum won't have a temperature, but there realistically is no such thing as a true vacuum. What few particles are zipping around out in space are very high energy and very high temperature, hence why the temperature of space has a physical value (typically pegged to the CMB, which will be around 2-3 K). Furthermore, there's another key consideration; many things overheat in space not because of high temperatures, but because of an inability to reject heat. All heat transfer is through either conduction, convection, or radiation, but conduction and convection both require physical contact, and radiation is significantly less effective. Thus, any object that relies on conduction or convection for heat rejection here on Earth would probably overheat in space."
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7ed3n8 | Why do chia seeds soaked in water spread uniformly throughout instead of settling at the bottom? | Chemistry | explainlikeimfive | {
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"Sorry I’m on mobile to forgive spelling errors. Chia seeds have a large amount of muscilin (sp?) that envelopes the seeds when they come in contact with water. This stuff is slimy yet sticks to the seed and I assume it evolved for seed dispersion. So each seed essentially gets a slime “air bag” when it gets wet and resembles a cell with the seed as a nucleus. It’s this slime bag which pushes against the other seeds. Eventually given time this coating will degrade and they will settle but usually the water evaporates and the muscilin will dry back onto the surface of the seed. Other such plant matter that has large amount of this stuff I know of includes ochra, which is utilized as a thickening agent in some gumbo/soup recipes."
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7ed5sm | if downloading a youtube video violates the terms of service, how do people get other creator's videos to comment on? | Other | explainlikeimfive | {
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"I mean they *could* be capturing the screen and watch in fullscreen or region capture to the video then record that and themselves with a webcam to comment on. They could also just be downloading the video, but youtube can prove neither.",
"Loop holes. This is what should happen. U go to a creator and ask if u can use one if their videos. They then send u the video that they have on their computer. U cut it edit it ect and upload it. This is what usually happens, or a combination. Some guy sees a sweet cut from a video, downloads the video and edits it into his own video then re uploads it. The problem is its very difficult for YouTube to tell the difference between a sent copy and a downloaded one and, for most cases isn't worth it. As long as the creator doesn't kick up a fuss about not having permission and the clip isn't a large portion of the video then YouTube doesn't care."
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7edja4 | How is music remixed? | I cant wrap my head around how people music so deeply. How can you isolate and edit/remove certain lyrics or instruments? | Technology | explainlikeimfive | {
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"When you record music in the studio, you record a bunch of different audio tracks (anywhere from 4 to over 100) and then mix those together to produce a final track. A proper remix starts with these raw unmixed tracks and then cuts them up, adds a few new pieces and creates a new song out of it.",
"Everything is recorded individually. So you have everything separate then mix it together.",
"Musician and producer here (amateur). I'm assuming you want to know how people without access to the original multitrack master recordings might do it. IE amateurs. There are several tricks to creating the parts to do a remix or mashup. The short version is that it is possible to replicate certain sounds, purchase the same samples or instruments that the original artist used, find and obtain acapella or instrumental versions of a song, or simply edit and process the original track to obtain different parts of the song like bass, solos, vocals, etc. I'll rank them from easiest to hardest 1. Technical trickery and available acapella or instrumentals. Find acapella or instrumental versions of a song. Using phase reversal, take one, or the other and add it to a track along with the original song and synced up. Since the two tracks are out of phase with each other, you end up hearing the two parts cancel out, and only hear whats left. IE get an acapella vocal, reverse phase, mix with original and you end up with an instrumental with no vocals. Re-render this to a new track and use along with the acapella and you got the lyrics and music separated. Another trick for getting vocals is that they are often in the center of the mix. So if you take the left channel and reverse it's phase, it tends to remove vocals from a track, leaving just the music. You can also do the opposite where only the center channel (vocals) is kept and the music is removed. 2. Re-do the song. Find out what instruments were used to make the original track or come up with your own sound alikes and use to make a backing track. 3. Editing mastery. Using low and high pass filters, filter the original track to remove any frequencies that don't belong to the parts you want to re-use. IE if you just want the bass guitar, you add a low pass filter to isolate it. You can also snip little clips of the song to remove drums or other instruments etc. Like say the beginning of the song has the drum beat with a bass guitar. The drums repeat, so using several sections where the bass plays over some notes in one section, and other notes in another, you can get the cleanest drums from each section to re-assemble into a clean loop with no bass guitar. This can be done for any part of the song provided there are reasonably un-busy sections of the song and enough sections of it. Some parts are in the left or right channel only, which helps isolate them as well. Using those techniques, you establish some parts you can use or re-use and then you can add additional instruments on top of it by tempo matching the source material. Tempo matching, along with re-sampling or slicing, allows the original samples to be sped up or slowed down without affecting pitch. Since many bands use stock synth sounds, or drum machines, samples, etc, it's often possible for an experienced producer to create a new arrangement using the same, and re-creating the song from scratch, then using either an acapella version, or carefully processed vocals from the original to add that element back. I used all of these techniques in[ this Queen - Lady Gaga mashup]( URL_0 )"
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7edtrz | Why do companies (Google, Apple, etc.) that have billions of dollars worth of debt not pay it off when they have the money for it? | Economics | explainlikeimfive | {
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"Imagine if your friend had a really weird system of borrowing money: For every $5 you give him today, he'll give you back $10 tomorrow (and you know he's good for it, no matter how much money you give him). Obviously you'd want to give him every cent you have, right? It'd literally double your money overnight! Hell, you'd want to go out and take as many loans as possible, just to give the money to him. Even if you had to pay ridiculous interest rates, you'd make a profit! For a less ridiculous example, imagine your friend has this system: For every $5 you give him today, he'll give you back $10 in a year. A bit less unreasonable, but this would still be a really great profit for you. You wouldn't give him every cent you have, obviously: You want to keep enough money to pay your bills for the year, buy food, save a bit for emergencies, and probably some spending money in case you wanted to buy a new game or go to the movies every now and then. Even so, you'll still probably want to give most of your spare money to him, because you'll profit so much off of it. If they lend it to you at a good interest rate, you might even borrow some money from friends or family *just* to lend it to your friend for a year, since you'll probably still profit from that. Even if you owed someone some money, it might be worth it to accept the late fees, because you'll have more money in a year from giving it to your friend instead of paying what you already owe. This is the system that big companies are in: They *could* pay billions towards their debt now, but that might not be the best way to use their money. If instead they invest it in their own growth, they might multiply it several times over within the next few years, meaning that (even with interest rates and inflation) they'll profit more in the end compared to if they had just paid off all of their debts right away. EDIT TO ADD: I tried to keep my explanation simple and focused just on one reason for this, but people in the comments have pointed out that it was overly simplified and missed some (more nefarious) elements of why companies might do this. Since I'm not an expert on the following, please take this next paragraph with a grain of salt, and look into it on your own to understand how it works: Companies might not want to bring money earned overseas back into the US, because that could cost them a lot on taxes. They might want to invest it, or if that's not possible or likely to give them a good return, they might just sit on the money until the government offers another repatriation tax holiday (When the government gives companies a time to bring money back to the US at a ***heavily*** reduced tax rate).",
"If you're paying 5% interest on debt, but can make significantly more on investments, it makes more sense financially to carry the debt than to pay it off.",
"Imagine you and your neighbour both had 10 dollars in savings and planned on buying a lemonade stand each for $10 and that can make $2 profit every day. You bought it with your savings, while your neighbour used $5 of his own money and borrowed another $5 with 10% interest. You both make $2 a day but your neighbour has to make 0.5$ interest payments, thus you earn $2 a day and she makes $1.5. However, you are getting a 20% return on your investment of 10 dollars and she is making 30% on his 5 dollars. Now, your neighbour realizes he still has another $5 in savings after buying his first lemonade stand. He decides to borrow another 5 dollars and use the rest of his cash to buy another lemonade stand. Now he has 2 lemonade stands and makes $4 a day and pays $1 in interest, thus making $3 for his 10 dollar investment. You both started with 10 dollars in cash and invested it in lemonade stands, however your friend is making 3$ every day and you are making only 2$! Of course, she carries a risk of the lender taking away his lemonade stands if she fails to make interest payments. NOW, in the real world you would have to pay taxes on your profit. Let's say a 50% corporate tax rate. Your lemonade stand makes 2 dollars so you end up paying 1 dollar in taxes. Your neighbour's two lemonade stands have sales of 4 dollars, but because her taxable income is calculated after interest payments, she is only taxed on 3 dollars thus paying only 1.5 dollars. At the end of the day your lemonade stand is paying 50% corporate tax rate, but your neighbour's two lemonade stands is only paying 37.5%. We call this a **tax shield**.",
"If you're making 10% a year on they money you'd use to pay your 3.75% a year debt, the best financial decision is actually to let the debt fester and keep investing. People do this too on a smaller scale, putting money into retirement accounts that get higher yields than what they're paying on their mortgage.",
"International companies issue debt with huge cash balances for a couple main reasons. 1) Overseas money is taxed at a high rate bringing it back. So it is better to park it overseas so Uncle Sam can't tax it. Instead they get historically low interest rate loans and promise to pay over 30 years. This money is then used for domestic needs. 2) If your debt is 4% interest and you can make 10% return on the same cash with investments, you essentially create a 6% net gain by not paying off your debt. (Same concept is applied to mortgage payoff vs long term investing) Side note: Repatriating money is hella expensive and there is trillions of money overseas. Whether or not you agree, the corporation was taxed at the country rate it was earned in, and companies don't want to be double taxed if they dont have to. So money sits idle in overseas accounts. Update: $2.6 trillion in cash overseas. If brought to USA, would be repatriated at 35% tax rate. Essentially forcing companies to not bother bringing it back.",
"Because debt isn't bad, and taking debt can sometimes be cheaper than using up your cash Apple specifically takes out debt in the US rather than pulling in overseas profits. Foreign profits are taxed when you bring the money into the US so they'd lose a good chunk of any cash they brought back, it is far cheaper to pay a couple percent and take out bonds when they're in need of more money stateside than it is to lose 10-20% bringing it in from overseas.",
"Some interesting answers here....virtually all of them wrong/partially correct (all the top rated ones I could see). Unfortunately this reason can't really be ELI5, but I'll try my best: The non-ELI5 answer is it has to do with capital structure policy and debt leveraging. Long story short, companies that utilize only equity financing (companies that have no debt) are at risk for hostile takeovers and buyouts. The reason for this is that companies that hold debt actually have a higher total company value, and therefore have higher stock prices (company management in public companies have what is called a fiduciary responsibility to investors, and that responsibility is to maximize shareholder wealth), lower costs of capital (the risks and costs associated with borrowing money for expansion and funding of projects), and higher earnings per share. In short, debt is valuable to the company that holds it. If a public company, like Google, were to pay off its debt, its total firm value could decrease by as much as 30%, if not more! Needless to say, investors would not be happy with that and would likely sue management for failing in their fiduciary responsibility. The SEC (the regulatory body over publicly traded companies like Apple and Google) would also have something to say about that action. Google and Apple would also then be left wide open for a takeover from another company because 100% of the company's equity (stocks) is up for grabs, and companies have no control over who buys and sells their stocks in the open market. If a company adopts a 50% debt to equity ratio (50% debt, 50% equity funded), only 50% of the company's stock is up for grabs, and it would be impossible for any single investor to rally a majority share in the company. Too much debt is bad, however, as it increases the riskiness of the company and worries shareholders. You have to crunch the numbers and find that golden mean that maximizes your firm's value while minimizing the risks associated with debt. Debt adds value to a company because the interest payments on that debt are tax-deductible (an asset), which reduces taxable income. The ability for debts to allow for expansion that is perhaps otherwise unreachable (lack of cash, for smaller companies) is a nonissue with large companies like Google and Apple. Despite the fact that these companies have massive cash reserves (Apple to the point where it's concerning for analysts, because cash held in the bank is cash wasted), they still use debt financing to pay for expansions when they clearly could have used their cash to do so. Why? Debt increases firm value. ELI5/TL:DR - contrary to how you think of it (as a negative thing), debt is valuable to a company, comprising 10-30%+ of a company's value at any given time (depending on the debt ratio of the company). Because debt adds value, it increases share price, which makes investors happy. It also keeps the company's ownership spread out so nobody can come in and buy a majority ownership share and take the company over (debt leveraging). The concern comes when companies have lots of debt, but small earnings. Source: work for an investment bank. Advise/consult clients about capital structure policy on a daily basis.",
"Because Debt is cheaper than equity. All ~~debtors~~ creditors want is a fixed amount of money, on a fixed date, and as long as that money pump is not threatened, they leave you the hell alone, they don't bother you while you are working. Equity owners are all like \"I gave you muh money, where is my return, you never give me enough, hey what are you working on, show me, dammit I own part of this! Nah do this like that, your plans are all stupid, don't you dare tank my share price\" and you are like jeez, i wish i'm never that desperate for money again.",
"People also forget that they keep hoards of cash abroad. It’s actually cheaper for them to borrow money, than bring them to states and having to pay additional taxes.",
"The other answers in this thread aren't correct, while some are technically true they aren't the reason corporations have debt. Corporations, especially large ones like Apple and Alphabet, meticulously manage their level of debt and equity financing. This is called the *capital structure* of a corporation, and it can vary due to many reasons. As some have mentioned, it can profitable for a company to reinvest rather than to pay off its debt, but the real reason they don't is because of what is called **leverage**. With debt, or leverage, a company can increase their relative equity earnings higher than if it were financed with equity alone. Let's illustrate with an example: *Company A* is financed solely through $100 of equity. Let's say that by the end of the year the company has earned $10 more. Since the company has no debts or interest payments to pay the equity is now worth $110, meaning an equity return of 10% (10/100=0.1) Now let's look at *Company B*. Company B has raised $50 of equity financing and another $50 from debt, which has to be repaid at the end of the year with 5% interest. Let's say Company B also earns $10 dollars during the year. At the end of the year Company B repays their debt, $50 + $2.5 in interest (0.05×$50=$2.5), and the remaining $57.5 is the property of the shareholders. The owners whom put $50 into the company at the start of the year have now earned a *$7.5/$50=0.15*, or **15%** return on their investment, higher than their counterparts at company A. They have *levered* their return higher. However, had the company instead lost money they would still had to have repayed their debts, and in turn lost more than the owners of company A. This is what leverage does, and why corporations have debt. Simply put, it increases the potential returns/losses of the shares to their desired level. As to why different companies have more/less debt compared to others, it depends on the volatility in value of the companies' assets. A car manufacturer that owns tangible, *safer*, assets such as factories, land, and raw materials can use more debt as those assets can be easily sold on the market. On the other hand, a company like snapchat whose earnings(or in the case of snapchat, losses) can vary largely won't hold a lot of debt as it can't be sure to be able to pay them in the future, and has no safe assets to have as collateral.",
"Just wanted to add in that there is a name for this and it's called the time value of money. It's the idea that if I had the opportunity to pay cash at a later date, how much more money could I make with the cash I didn't have to pay out. Companies might take out a loan for 4% per year but they expect they will be able to make say 10% per year with the money. It's also why when companies send out invoices they have terms on them. For example, 2/10, n/30 pronounced \"two ten net thirty\" this means that if the buyer pays within 10 days they will receive a 2% discount, otherwise the net amount is due in 30 days. Its an incentive for the buyer to pay early. The seller does this because the earlier they can get cash the sooner they can start making more money with it. It's also because when the buyer hasn't paid, as time passes the chances of buyer paying becomes less and less. I know that was more than you asked but just wanted to add that.",
"The most common reason is that they need money in the U.S. while they hold profits overseas, and would have to pay tax to bring it back to the U.S. Better to pay 3% interest then 35% income tax.",
"Cheaper to issue debt than repatriate cash from overseas. Interest paid on debt is tax deductible. It all comes down to the cost of capital",
"For a large company, to finance their operations they need to get money from outside the company. This can be either from debt or the equity market (stocks mostly). Both have a cost associated with them. Debt is cheaper than equity because debt is considered to be a safer investment, but only to a point. Eventually, having too much debt makes it riskier. But all companies have a certain amount of debt because if they were entirely funding themselves through equity they would be spending more money than they needed to on their financing. It's called \"cost of capital\", and investors demand that debt be included to bring the overall cost down, so companies never get rid of it even when they can. It's not the same as personal debt where we want to get rid of it as soon as we can.",
"In lots of countries there is a tax on profits, profits are equal to all revenue - costs, the trick is to bring your profit to 0 so you have to pay almost no tax.",
"Because money makes more money over time, so if Apple has to option to pay debts slower than they actually need too, they can use the money not spent on these things to gain more interest from investments."
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7edy01 | how do we produce carbon dioxide when we exhale. | What causes this to happen? | Biology | explainlikeimfive | {
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"When your body consumes food it's organic matter is in three categories: sugars, fats, and proteins. Unless you ate too many or are one a keto diet, proteins break down into amino acids to build your own proteins. Sugars and fats are broken down for energy. Fats are broken down into less complex compounds like sugars. The sugars are broken down to ultimately produce carbon dioxide, water, and energy. The carbon dioxide enters your bloodstream where it is carried to the lungs and leaves the blood stream via diffusion. SO, the food you eat, the fat you burn, everything your body converts into energy gets breathed out as CO2. Extra fun fact, as a result of this process, the oxygen you breath in actually becomes water as part of the breaking down process. SO you breath out your food and pee out your air."
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7edzdk | Why does some restaurants have a Letter rating from the Sanitation inspection and others just have a pass/fail. | Restaurants post their ratings on the window and some have letter ratings and others simply say "Pass". Why are their two different rating systems? | Other | explainlikeimfive | {
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"Do you mean some places on the same street/city, or just in general. Some states use a simple pass/fail system, and some use a letter grade system, with 69 and below being the failure level. Each area has their own processes."
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7ee1h4 | Dialectical Theory | I'm having trouble with this in my communication class and I need an easy explanation | Other | explainlikeimfive | {
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"A dialectic is a discussion between two opposing viewpoints with an emphasis on logical reasoning. They seek to refute each other's point of view while promoting their own. The goal is to reach a mutual understanding and to flesh out the theories themselves. Dialectic is related to the word dialect, relating to a kind of speech. Edit: Rather than simply expounding on your idea, the idea is expressed in conversation and defense of the idea."
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7ee999 | If I boil a kettle does everything inside become sterile? if so how long does it stay sterile? | Chemistry | explainlikeimfive | {
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"Actually sterilized? No. Boiling water and steam are damned effective at killing germs, but you generally need much higher temperatures than you'll achieve in a kettle to reach an effectiveness where you can call it sterile (99.9999999% of microbes killed). In particular, bacterial and fungal spores are generally tenacious little bastards and will survive. For medical sterilization, when steam is used, it's heated under pressure to a much higher temperature than is normally attainable, and objects are kept in for as long as 30 minutes. As for how long it stays sterile? Until it isn't. Once your sterile tool touches something nonsterile, it's contaminated.",
"If you boil water in a pot, or canned food inside that boiling water, and you keep the temperature at boiling for several minutes, then yes it is sterilized. However in order for something to stay sterile it must be sealed to prevent re-innoculation by fungi, bacteria, or virus. It's actually more common to use steam to do this than boiling water, as boiling water stays at 212F and no hotter (at sea level in pure water) where as steam can get as hot as you can make it. How long it will stay sterile is a matter of how long it can be hermetically sealed without exposure. If it's kept sealed, it's indefinite, since in order to be non sterile, it has to have living organisms in it, and if they have no way to get in, and the ones that were already there are all dead, then it stays sterile . The act of boiling a food product to prevent spoilage is called pasteurization named after the famous French microbiologist Louis Pasteur whos groundbreaking research on the subject is one of the greatest achievements for human kind right along side the development of vaccines, and the discovery of antibiotics. There are other ways to sterilize something than just boiling. Anything which kills living cells can do so. You've probably heard of irradiating objects to sterilize them. This replaces boiling water with hard ionizing radiation which serves a similar purpose, but without altering the texture or flavor of the food. It's also used for sterilizing medical supplies like scalpels, bandages, dressings, etc."
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7eebpc | Why are bugs attracted to light? | Other | explainlikeimfive | {
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"Some bugs navigate by the moon, put the moon on your left and keep going, for example. Artificial lights confuse them if you put a light bulb on your left and keep going you go in a circle"
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7eep4b | Why do most song lengths seem to fall between 2 and 4 minutes? | Other | explainlikeimfive | {
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"Much of the answer has to do with the length limitations of vinyl 7\" 45 rpm singles, which for many years were the primary means of promoting a single song. You can only fit about 3 minutes of music onto a 45 rpm single. So historically, if you wanted to write a hit pop song, you had to keep it under that length. More here: [Why Are Songs On The Radio About The Same Length?]( URL_0 )",
"Top 10 charts have a lot to do with it. If you have 10 songs at 3 minutes each, you can get them all into a 30 minute radio segment.",
"[Billy Joel explains it in The Entertainer]( URL_0 ) > \"It was a beautiful song, / but it ran too long / If you're gonna have a hit, you gotta make it fit / So they cut it down to 3:05.\"",
"It has to do with which kind of music you're talking about, and how it came to be. Most modern music is influenced by the radio station format, where it's convenient to have songs that span between 3 to 4 minutes tops. You'll even find \"radio edits\" of longer songs. There is also the format: early vinyl records were 10 inches in diameter and held only 3 minutes. Jukeboxes play 45 rpm records, and they span (surprise!) 3 minutes. So artists/record companies made songs that fit that length. If you look at classic music instead, you'll that symphonies are way longer than 3 minutes. Some of it was created for theater plays, or just orchestra. Since people would go to a venue and sit down to listen, lengthy pieces were expected. In less popular modern music timings vary a lot too. Most of these artists are not concerned with radio play, so they just do whatever they want, or what the genre they play expects of them. So you can find super short songs: URL_1 Or really lengthy ones: URL_0 In short, length depends on the purpose of the music, the format, its audience, etc."
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7eeya2 | Why does orange juice taste awful after brushing your teeth ? | Chemistry | explainlikeimfive | {
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"Brushing teeth causes your taste buds in the tongue to be hightened (to be more sensitive). This increases the intensity of flavors and usually creates a bad taste for almost every food. Orange juice has both sweet and bitter(because of the pulp) flavor but the sweetness is usually dominant and clouds bitter taste. After you brush, you feel more of this bitter taste which feels relatively awful.",
"There is a chemical in many kinds of toothpaste that makes the toothpaste foam and spread around easier. A side effect is that it suppresses our sweet taste buds and breaks up a fatty molecule that usually suppresses our bitter taste buds. That means we can't taste sweet stuff very well and bitter flavors are stronger than usual. So everything tastes awful until we rinse out our mouth with water or wait for saliva to do it naturally over time."
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7ef209 | why do tongues get weird bumps when burnt or after eating something really sweet or really salty? | Biology | explainlikeimfive | {
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"Shortest answer: your tongue always had those bumps, but they are usually very small. If something is to hot/sweet/salty than it's prepared for, it will swell. This brings in white blood cells faster than usual since your body isn't certain if it's an infection or not, and it also circulates the blood more so the temperature is regulated and the cells have the resources to repair any damage. & nbsp; More detailed answer: Your tongue is always made up of these little bumps called \"Lingual papillae\" (unless you have a certain health condition that causes the tongue to have a smooth and irritated area.) When they are burned or come in contact with something that is extremely sweet or salty beyond what it can tolerate, the area gets irritated by the extreme exposure and will swell, making them more visible than usual as a side effect The area swells as a side effect of increased blood flow which helps regulate temperature, deliver nutrients to repair any damaged cells, and deliver an increased amount of white blood cells in case there is an infection. The body tends to respond to negative stimulus by sending in all the available methods of treatment so even if your tongue is just burnt you will get the automatic responses intended for temperature, physical trauma, and infection all at once just to be safe."
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7efanf | How do we know that interstellar asteroids, rogue planets, cool brown dwarfs, and pockets of gas don't account for the remainder of the mass in the universe? | Physics | explainlikeimfive | {
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"So basically the process we have gone through is the following. We tried estimating the mass of our solar system whose objects masses we can estimate quite accurately so for example we know for a fact that the sun is roughly 99.86% of the mass of our solar system, so even Jupiter which is the second largest and heaviest object in the solar system is more or less negligible when it comes to mass of stars. So, imagine if all star systems in the universe are holding this same ratio (or even a higher one cause we know a huge number of stars that are much much bigger and heavier than our own sun). This way we can have a rough estimate for the mass of an entire galaxy if we estimate the number of stars per galaxy accurately enough. When scientists tried to apply this method of estimate on far away galaxies, they found out that the effect of gravitational pull of these galaxies (galactic clusters to be more accurate) we found out that the number we had using estimates was around 5% only of the actual mass we are witnessing. You might think well, our estimate was wrong but in fact, it can not be that way off. Also, we did not have an explanation for this huge difference and if it was causing the universe to expand, thus we called these \"Dark Matter\" and \"Dark Energy\" cause we really know so so little about them at the moment. As for asteroids and meteors specifically, they are actually too spaced our to matter in the mass calculation and they were actually accounted for in the 98.6 % calculation I mentioned earlier. To put this into perspective, the mass of our sun is roughly 2x10^30 Kg while the mass of all the asteroids in the asteroid belt combined is roughly 3x10^21 Kg. meaning the sun is a billion times heavier than all asteroids combined. Hope this helps",
"We are missing like 85% of the mass. I mean sure maybe, but that's an awful lot of undetected things, vs the possibility of stuff we just can't detect. It is a lot more likely there is something we can't detect than just a ton of stuff we have missed but could see.",
"The stuff that planets, brown dwarfs, etc are made from, baryonic matter, interacts with light. If the missing mass was baryonic, we'd be able to observe it somehow; either it would be stars or other hot bodies that emit electromagnetic radiation, or it would be clouds that block light. With the amount of missing mass, there's no way that our technology would miss it if it is baryonic. So, there's lots of mass out there that doesn't interact with light at all, which defies what people think about normal matter."
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7efd40 | Why does cannibalism cause kuru...but not when you eat other species unless they're infected cows? | So from my elementary research I think I got this down. Partake in Cannibalism = Kuru, mad cow disease, etc. you go crazy because unraveled prions from eating the cannibalized meat will cause your own brain's cells to unravel, and so on Eat other species = yum Eat a cow who has mad cow disease (because they were forced into cannibalism) = you get the mad cow disease...presumably because their unraveled prions also got to your brain and did it's magic? So how come there is such a strong connection to eating your own species causing kuru, but not so with other species unless they're also mad? | Biology | explainlikeimfive | {
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"Cannibalism doesn't cause kuru. it was transmitted among a very small group of people, because they somehow got it and their unusual funerals led to it being passed along. No one has gotten this disease in decades. There are many similar diseases, generally all referred to as \"Transmissible spongiform encephalopathy.\" The proteins involved are not unravelled, they are misfolded. Cannibalism does not cause these things, it only spreads them. They are caused by proteins becoming misfolded. This would normally only affect the organism it happened to, but through cannibalism it spreads to others. The type that spread to humans from cows was a variant, and one which most people were immune to. ONly some people with a genetic defect affecting some amino acids could contract it. But because so many people ate it for so long, it was bound to happen eventually. The reason eating your own species matters is because unlike mad cow disease, which affected only a very small number of people, if the prion exists in a member of your species that means it can easily adapt to you without any special changes needed and is spread without effort. From any other species it would require a mutation that allowed the prion to grab on to part of you, and thats not very likely.",
"The leading theory for BSE (mad cow disease) was that it emerged due to sheep infected with scrapie (another prion illness) being used for the bone meal fed to cows. So, sheep with scrapie get eaten by cows = > BSE, and when those cows are fed to humans = > nvCJD. The subsequent use of BSE infected cattle as feedstock (via bonemeal) led to a spread of the infection. I believe this is the case with Kuru too - Kuru didn't emerge from cannibalism, but rather spread via cannibalism. Not all prion illnesses are spread via ingestion. In fact most are primarily familial. It has also been spread in labs across other species. Perhaps most notable was a French lab that managed to infect \"humanized\" lab mice with scrapie (indicating that scrapie too can be transferred to humans). And there was also an instance of CJD being transferred from one person to another due to a corneal transplant. Prion diseases are weird and not yet properly understood."
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7efem4 | How can the sum of all natural numbers be negative? | Mathematics | explainlikeimfive | {
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"text": [
"It's not really, but it comes from a certain natural way of assigning values to infinite sums. For example, it is certainly true that 1/2 + 1/4 + 1/8 + 1/16 + ... = 1. It's also the case that 1 + 1/3 + 1/9 + 1/27 + 1/81 + ... = 3/2, and that 9/10 + 9/100 + 9/1000 + ... = 1. Rather than dealing with each of these infinite sums individually, we can determine that for any sum of the form a + a\\*r + a\\*r^2 + a\\*r^3 + ..., where -1 < r < 1, the sum is equal to a/(1-r). In the first example, we have a = 1/2 and r = 1/2, so the sum is 0.5/(1-0.5) = 1, while in the second we have a = 1 and r = 1/3 and in the third a = 9/10 and r = 1/10. Of course this is only valid for the case where -1 < r < 1 specifically: if we look at the case where a = 1 and r = 2 then we get 1 + 2 + 4 + 8 + ..., which clearly grows to infinity. But if we *did* want to assign this series a finite value for some reason, then it would make some degree of sense to pick the value we'd get if we pretended like the a/(1-r) formula worked for all possible r. In that case, we would assign the value 1/(1-2) = -1 to the sum 1 + 2 + 4 + 8 + .... Does this mean that \"1 + 2 + 4 + 8 + ... = -1\"? No, just that -1 is what our function would suggest if we extended it to the case where r = 2. There's a rather more complicated function which evaluates sums of the form 1/1^p + 1/2^p + 1/3^p + 1/4^p + .... In this case, the sum is well-defined whenever p > 1; otherwise, it diverges to infinity. But the function that gives us the value of the sum, called the \"zeta function\", can be applied to many values of p outside this range, just as our a/(1-r) function could be applied to many values of r outside the range -1 < r < 1. It turns out that the zeta function assigns a value of -1/12 to the case p = -1. So we might assign the value -1/12 to the series 1 + 2 + 3 + 4 + ..., although the sum itself does not actually exist since the series grows without bound.",
"It's not. In fact that sum diverges. So where does this \"fact\" come from? There's this famous mathematical function called the zeta function. It can be expressed in certain parts of the (complex) plane as the sum of the natural numbers to the negative z power. This expression holds for instance when the the real part of z is greater than 1. When z= -1, the zeta function assuming the old expression still holds looks like it should be the sum of the natural numbers. In fact, this expression is garbage. In reality, one considers what is called the analytic continuation of the zeta function. This thing has the property that its value at -1 is the number -1/12. Sorry for bad formatting. On mobile."
],
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7efjjj | Why do our brains feel "fried" after a period of concentration? | Biology | explainlikeimfive | {
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"text": [
"The brain is like a machine that requires energy to function. Each individual unit called neurons eat up sugar and other nutrients to communicate other. now there are parts of our brain that do signaling and other parts of the brain do the interpreting your brain works double, like reading, and interpreting a song, or doing a complicated math problem. This puts your brain in a very active state. This active state will produce by-products or waste, much like a factory after production. Now the waste product of the brain is built up. Specifically these by products are called adenosine etc. Now these waste product will signal your brain needs to rest. This will explain why you feel sleepy at the end of the day, or why after a long study you feel \"fried\". Its your brain's way of saying it worked hard and you need to rest. This signals your brain to sleep or feel drowsy. Hope it was a good ELI5, my first attempt.",
"When your brain works hard, it uses a bunch of energy. If it did all the time, you'd have to consume way more food (in the past, this could be deadly). Feeling \"fried\" is feedback to prevent this.",
"The brain, like any organ, consumes energy when it is active. Thinking hard means consuming a lot of energy. It also creates waste products that need to be cleared. So feeling fried is infact the feeling of having certain resources drained, and the process of cleaning up the mess. Happy thinking!"
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7efuuc | How do we sometimes "feel" someone is looking at us? | Biology | explainlikeimfive | {
"a_id": [
"dq4pt7e",
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"text": [
"I found [this]( URL_0 ) article that explains it pretty well.",
"You saw them looking in your direction, subconsciously or otherwise. There's no mystery here."
],
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"https://www.google.co.jp/amp/s/www.psychologytoday.com/blog/the-narcissus-in-all-us/201102/how-you-know-eyes-are-watching-you%3Famp"
],
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7efvvy | Is drinking 8 cups of any liquid (i.e. pop, juice, coffee, beer, etc) pretty much the same as drinking 8 cups of water in terms of hydrating your body since the primary ingredient in any drink is water? | Biology | explainlikeimfive | {
"a_id": [
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"text": [
"There's some difference. First these beverages are high on water, but it's not all water. Cola has like 88% water in it. Black coffee like 98%. Also, the amount of minerals make it either easier to absorb and keep the water, or harder. If you'd drink something high on salt (like sea water), you'd actually get really sick because partially the salty water in your bowels will attract water from you. This will cause diarrea and causes dehydration. Some ingredients work as a diuretic, which means you will pee more because of them. Think of beer and coffee. While uptake may be the same as with normal water (but probably isn't the same) you also excrete more of it. So, the additional ingredients do matter.",
"In amounts of liquid yes, will it have the same effect? No. If you were to drink 8 cups of salt water you would get more dehydrated because of all the salt. Coffee and beer ord alchohol in general makes you pee more so in the long run you will get more dehydrated from this as well."
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7efz23 | What stops pop up ads and viruses from simply making the "no" or "cancel" button take users to the same place as the yes button? | Technology | explainlikeimfive | {
"a_id": [
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"text": [
"Nothing. Personally, I never click popups. You can easily get rid of them by: - F12 (open devtools) - click the \"Select Element\" button (top left of devtools, looks like a mouse cursor) - mouse over the popup so it is highlighted and click (won't trigger a normal click) - adjust if the popup is inside an iFrame or similar - right click the element and \"delete\" - profit. (With practice, this takes me ~1-2 seconds) Edit: Apparently this can be brought down to about 15ns using /u/ajgz 's shortcuts below :)",
"Below is one reason why they can't do this. There may be workarounds or other methods I'm not aware of. To hijack your browser and prevent you from closing the tab most of these companies use an alert window which is different from a regular popup. This window is a terminal event you must interact with it before you can do anything else. This window is actually generated by the browser not the website you're visiting. So the website can launch the window but can't really control what happenes if you press cancel (the browser handles that)",
"Nothing. Plenty are simply an image link and will direct you regardless of where you click. It's why protection with Malwarebytes and uBlock Origin is so essential."
],
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7efzk9 | What is defamation and how can you be sued for it in a country like the US where there is free speech? | Other | explainlikeimfive | {
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"text": [
"American free speech rights aren't unlimited. We've established that you can't threaten to murder people, shout fire in a movie theater or engage in false advertisting. Defamation falls under the same umbrella. While the bar is set quite high, you can sue somebody for slander/libel if you can prove that... * the statements are untrue * the person speaking knew they were untrue * but they said them anyways * ...and they caused you actual, quantifiable harm You can say \"Donald Trump is a doo-doo head\" all you want & there's not much that can come of it. If Burger King starts placing ads saying \"McDonald's burgers are made with rat meat\", OTOH, that's a cause for action."
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7efzpx | Today I saw maternity menstrual pads for pregnant women, what are they for? | Biology | explainlikeimfive | {
"a_id": [
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"text": [
"Some (most, if not all) women experience extraordinarily heavy flow for their first/second menstruation cycle after giving labor, as their uterus can (usually) actually begin to bleed during this period. Maternity menstrual pads are more absorbent, softer, and larger than other pads.",
"Almost immediately after you have a baby, you start bleeding. It’s called lochia, and it’s basically the equivalent of every period she missed while she was pregnant all happening at once. Her uterus doesn’t need the lining any more now that there’s no baby to grow, so it does a massive bloody spring clean. The huge maternity pads are for *that*."
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7eg7ja | Why are octopi classified as mollusks? I always thought they were cephalopods and TIL they’re not. | Biology | explainlikeimfive | {
"a_id": [
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"text": [
"Kindom > phylum > class Animal > mollusk > cephalopod To the same effect humans are: animal > chordate(has a spine) > mammal. Mollusks are invertebrates with unsegmented bodies. Cephalopods are defined by their body being just a head and tentalces for apendages. As far as i know all cephalopods are also predators unlike gastropods(snails) which operate at muliple tiers in the food chain.",
"Cephalopods are actually a kind of mollusc. Phylum Mollusca, class Cephalopoda. So they're both."
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7egb4u | Why does Apple not build its own manufacturing plants? | if Apple is having so much trouble sourcing enough iPhones to meet demand, and labor issues in third-party OEMs routinely cause bad press, why hasn't Apple already used it's massive cash reserves to build some insane mega-manufacturing plant where everything is in sheer white and Jony Ives' voice floats softly out of loudspeakers at all times? Why does Apple not follow the Tesla model of designing the manufacturing process itself when Apple is so clearly committed to vertical integration? | Technology | explainlikeimfive | {
"a_id": [
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"text": [
"Money, it's all about money. They are not making products out of the goodness of their hearts. It's to make a profit, and so far they have ran the numbers and they would make more how it's currently operating.",
"Apple doesn't make anything that requires them to build their own cutting edge manufacturing plants. They can just buy parts from other people & send them to Chinese factories for assembly. When you're dealing with something commoditized, like LCDs, mobile semiconductors & electronics assembly, it's far cheaper to contract it out and let people complete for razor thin margins on it. Compare this to Intel. They need to spend billions of dollars building factories every few years because they're pushing the envelope of semiconductor manufacturing & are years ahead of the #2 company in the industry. A big part of what they offer the market is having the absolute best tech."
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7egp6s | Why does the urge to pee increase the closer you get to a toilet? | Biology | explainlikeimfive | {
"a_id": [
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"text": [
"Without getting into learned behaviors and neurology, one simple explanation is that the bladder contains both voluntary and involuntary muscles. The big muscle that essentially coats the entire bladder to help it expand/contract is involuntary, and you've also got an involuntary \"internal urinary sphincter\" that acts as as a gateway out of the bladder. On the other hand, you also have an \"external urinary sphincter\" which is under your voluntary control. When you're holding in your pee, you're doing it with the external sphincter. Although the voluntary and involuntary parts are controlled by different nerves, there's evidence that they influence one another. When you voluntarily relax the external sphincter, the involuntary parts will go along with it. This means that when you're getting close to the toilet, you're letting down your guard on that external sphincter, so the rest of the bladder starts making an effort to pee."
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7egr9h | Why some clouds sit very low to the ground while others sit extremely high up? | Other | explainlikeimfive | {
"a_id": [
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"text": [
"There's a lot of different reasons and factors around clouds forming, but as a rule of thumb — heavier clouds with bigger density of moisture float down, while lighter are pushed up. More detailed, clouds are microscopic particles of liquid being held in the air by ascending flows of air. Therefore, with equal flow power, more dense clouds will float below light ones. And when there's too much water to hold it in the air by upward flow, it falls down in a form of rain or snow."
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7egs4l | What’s the purpose of a distress signal on submarines, if we can’t locate them once it’s been used? | We've all heard the news about the Argentinian submarine which has gone missing. I am just wondering, as they have sent a distress signal, but we don't seem able to locate them, what the purpose of the distress signal is? | Technology | explainlikeimfive | {
"a_id": [
"dq4vxpd",
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"text": [
"Think of the distress signal as someone yelling out \"Help\" really loadly into the night, someone hears them and calls the police. The call doesnt tell you exactly where they are, but it does tell people to start searching and gives an approximate starting location.",
"If they never send a distress signal, how would anybody know that they need help? Also you can locate the radio source, but they have probably been moving since the sent it out, thus making it hard to find them.",
"It would appear they didn't send any distress signal. Perhaps the EPIRB wasn't deployed or malfunctioned."
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7eh04m | why metal screws aren't attacked by the body when inside bones | I had ACL surgery a couple years back, and i got these metal screws that hold the new ligament in place in my bones now. Why are they not recognized as foreign objects and attacked like other things? | Biology | explainlikeimfive | {
"a_id": [
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"text": [
"They're made out of a titanium alloy that the body doesn't recognize as a foreign substance - they're biologically inert. I'm not really sure why it works that way, but it's widely used. URL_0",
"The body doesn’t have an all knowing list of things that are foreign and things that aren’t; evolution has primarily pushed us to recognize and attack things that generally are harmful to us, like germs and poisons. The titanium from which the screws are made of has never been a real threat to the body and as a result, we have never evolved to attack it.",
"Recognizing a foreign object is basically down to chemistry - if a thing doesn't react to cells and fluids in the body in any way, then it'll not be recognized as anything or cause a reaction.",
"As said above titanium , Titanium alloys Ti6Al4V or stainless steel is used. These are corrosion resistant. Titanium is the most recent material addition to implants. It is less likely to have a reaction based on the fact that it is more corrosion resistant compared to stainless steel. In some cases, materials like plastics it is the shape and size that can determine whether the body reacts to it."
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7eh5wk | Why do humans need their tonsils removed? | Biology | explainlikeimfive | {
"a_id": [
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"text": [
"We don’t *need* them removed - I’m nearly thirty and still have mine - but in some cases the tonsils can get infected and inflamed. It’s painful, it’s miserable and it means the owner of the tonsils feels like shit for ages as the infection keeps coming back. In a situation like that, removing them altogether is a simple way of solving a recurring problem."
],
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7ehbqm | Why do we get itchy? | Biology | explainlikeimfive | {
"a_id": [
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"text": [
"Itching is a habit our body developed as a way to protect us, just like feeling hot or cold. It lets our body know that something bad might be endangering it. Our body has things called \"pruriceptors\", tiny itch-sensing nerve-ends. Whenever our body is in a bad situation, whether it's \"real\" (like hot or dry skin) or in our heads (like feeling awkward), these ends get \"excited\" and they ask us to itch. Once we itch, our brain will know something is wrong, and it will release things that make us feel good, to overcome the pain. It doesn't fix the problem, however, so be sure to see a doctor if you're itching too much! (my first ELI5, I hope I did it right)"
],
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7ehdo9 | Could someone explain network encapsulation and how data is split up into frames and packets? | I've recently been set an assignment where one of the questions goes along the lines of "how is data encapsulated and split into packets and frames?". The teacher hasn't really given a answer to this so can someone give a simple explanation for me to base my answer off? | Technology | explainlikeimfive | {
"a_id": [
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"text": [
"So in general when people talk about the network stack they use the [OSI model]( URL_0 ). You can think about it this way, at one point you have a piece of data on your computer and you want to send it to another computer. In order to do so, your data has to traverse this so-called network stack. Each layer of this stack has different responsibilities and so requires its own header or metadata to be added to the original message. Adding this extra information at each level is called encapsulation, removing it when it arrives at the destination is then de-encapsulation. So we've started at the application layer. Then you walk through the steps of sending the message. First you add any application layer metadata you want to add (like a REST header). Then you add whatever information you need for the presentation and session layers, but at this point it's still all part of the data layer. Next you move to the transport layer. This is where the message gets broken up into packets (technically datagrams packets). Each packet has a TCP or UDP header added that contains information about where the packets need to go and how to reassemble them at the destination. The data is broken up into packets at this layer so you can \"fit\" the data into the network. Now we move to the network layer. At this layer you're working with routers and IP addresses. Basically this layer moves the packets around between networks. Next is the data link layer. This layer is what handles communication between two nodes on a network, say between two routers or a computer and a router. It's purpose is to guarantee the message gets across a single wire without errors or data corruption. Messages are broken apart into frames and each frame contains an ordering number, so the layer can tell if the message got across successfully. Lastly is the physical layer, which is just the electrical signal carrying the data. Here you add error correction bits to the data. _Now_ that you finally have each lower layer's data encapsulating the upper, your message is ready to be sent across the wire as electricity. When it arrives at the destination or intermediate hops, the headers are successively stripped as you work your way back up the layers, until your message arrives at its destination application (layer)."
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7ehdy1 | How air fresheners like febreeze actively remove bad odours not just cover them up and how do they decide what is a bad odour? | Chemistry | explainlikeimfive | {
"a_id": [
"dq4ysj3"
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"text": [
"The active stuff in Frebreze is a huge sugar molecule. It traps and binds the tiny and much lighter \"smell molecules\", making them much more heavy. Being heavier significant less \"smell molecules\" travel the air and can be detected by your nose."
],
"score": [
30
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7ehqvm | How can a person be in "critical but stable condition"? | Biology | explainlikeimfive | {
"a_id": [
"dq500xk",
"dq502xz",
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"text": [
"\"Stable\" just means \"Not getting worse\" If you're in a coma because you stuck your head in front of a moving bus you're in critical condition, but not currently dying and therefor stable.",
"They mean two different things. The \"critical\" part means \"they're in really bad shape\", while the \"stable\" part means \"but they're not getting any worse\".",
"Since this is an ELI5: critical and stable are two different things. If your dog is ill and needs a plaster, that's critical for him. If your dog is ill and is not getting worse, that's stable. So your dog can need a plaster and still not recover, being critical and unstable, or can only need a bend-aid being non-critical and stable."
],
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7ehrru | why do we need oxygen | Why do we need to breathe oxygen what is it used for and why do we die after a short time without it | Biology | explainlikeimfive | {
"a_id": [
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"text": [
"**Oxygen lets your cells release more energy from the food you eat. Without oxygen, large organisms could not get enough energy from their food to survive.** The food you eat has three types of molecules that can give you energy - carbohydrates, fats, and proteins. We measure the energy one molecule can give your body in ATP. Without oxygen, your body can make: * 2 ATP from one carbohydrate molecule * 0 ATP from one fat molecule * 0 ATP from one protein molecule With oxygen, your body can make: * 36 ATP from one carbohydrate molecule * 72 ATP from one fat molecule * 36 ATP from one protein molecule Your body is always using a lot of energy. It comes from being a warm-blooded, large animal with a big brain. If the cells of your body do not always have enough energy, they will die almost immediately. When you cannot get oxygen to those cells, they cannot make enough ATP to survive. Look again at how wildly different those numbers are above. The above is highly simplified, but it explains the point. In reality, there is a wide range of how many ATP can be generated from each molecule type, and protein is rarely used by the body to make energy. The important point is to understand the scale of the difference in how much energy your cells can release with and without oxygen."
],
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7ehwld | Asexuality as a sexual orientation for people | I am having difficulty understanding asexual people. One of my friends came out as one and I want to understand what it is before I have coffee with him next week. I just don't know what to ask or say. Just want to support him where I can. | Other | explainlikeimfive | {
"a_id": [
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"text": [
"It's not so much an orientation as an inclination. Kinsey used to talk about a 0-6 scale of sexual orientation. Where 0 is heterosexual and 6 is fully homosexual. People can have orientations in-between at any grade. We should add to this a second axis which is strength of sexual interest. A person might be heterosexual but almost entirely uninterested in physical sexual activity and unattracted to females or males. This person may still find a fulfilling romantic relationship. Asexuals tend to date other asexuals since relationships tend not to do well when people have different levels of interest in sex. Since our society is so oriented around persuit of sex, being asexual can be isolating.",
"**Heterosexuality** is (sexual) attraction to people of the opposite sex. **Homosexuality** is attraction to people of the same sex. **Bisexuality** is attraction to people of both sexes. **Asexuality** is attraction to people of neither sex.",
"URL_0 The AVEN website has a lot of useful explanations and FAQ's which might help you. As far as seeing your friend, is he likely to bring it up and discuss it himself? If he isn't, then it's probably no biggie. Someone else's sexual orientation only really needs to be discussed if either they bring it up or you're interested in pursuing a relationship with them, otherwise it's irrelevant to most things. I'm glad you're being supportive, asexuality is quite rare and misunderstood, but he's still the same friend you've always had.",
"Don't ask him whether he masturbates or not. For comparison, an anorexic may not want to pig out on a large pizza but still needs water and maybe some vitamins to survive."
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7ei091 | Do bacteria have bacteria? | Biology | explainlikeimfive | {
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"Bacteria *are* bacteria. I am not sure what you mean by \"have bacteria\". Do you mean \"have bacteria on them\"? If so, bacteria often climb over each other and interact directly with one another. But they don't have tiny bacteria living on them, just like elephants don't have tiny elephants living on them.",
"If you meant inside of them, maybe yes..some bacteria eat other bacteria. Whats interesting is viruses. Many bacteria are infected by viruses which sometimes forms a symbiotic relation.",
"There are theories some of the complexities in our own cells (e.g. the mitochondria, you might have heard of them) are the result of one bacterium engulfing another and then both profited of it and kept on living like that, which is called the endosymbiosis theory. Whether a tiny bacterium can \"infect\" a bigger one and thereby be disadvantageous (i.e. making it \"sick\") seems therefor not unlikely. I have no sources to back that up, though. However, when bacteria infect an organism (humans, animals, insects, etc), it makes it sick by being inbetween the cells and releasing toxic chemicals. It does not actually go inside our individual cells. Because a bacterium only consists out of one cell, another bacterium could not infect it in the same manner as it would one nog us. As earlier mentioned, there are viruses that can infect bacteria, called bacteriophages (phage is another word for virus). They DO get into the cell of the bacterium. They're rather cool, because they can be used as an antibiotic when we humans have a bacterial infection. Though lots of that is still being researched. I hope this bis clear, enough. A five-year-old would probably not know what a cell is, so if I have to explain that, let me know :) One a side-note: mitochondria is the powerhouse of the cell."
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7ei5du | Why does a pencil look like it is made of rubber when you wiggle it between two fingers? | I recorded it in slowmo thinking it would look straight but it looked even more wiggly like rubber. | Biology | explainlikeimfive | {
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"The “rubber pencil” illusion is caused by our eye’s bad perception, the pencil is simply moving to fast for our brain to create an accurate picture.",
"When it moves that fast, our brain can't process what it looks like at a particular instant. Instead we see a blur. We start to process the shape when the portion we look at is moving slowly enough. Near the tips, the pencil is moving the fastest, so we only resolve the shape at the very moment the pencil stops and reverses direction. A bit closer in, we can resolve the shape a bit earlier when the pencil is closer to the center line. And so on until you get to the very center which is reasonable the whole time. The end result is that the points where the pencil is moving slow enough to be resolved form a curve, so we perceive the pencil as curved. The reason it looks wobbly with a camera is likely completely different, and due to the rolling shutter effect: a camera scans front one end to the other to record a frame. This takes place inner a period of time, during which the pencil moves. Since each part is captured at a different angle over time, the pencil is recorded as a curved object."
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7eitiv | How can simulated flavors (such as fruit) be made without even having real flavoring in it? | Chemistry | explainlikeimfive | {
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"Synthetic flavours are made using chemical molecules that activate similar receptors in our mouths. By trial and error, people figured out that adding some chemical groups onto organic molecules, we can simulate fragrances and flavours. For example, Ketones (chains of carbons with an oxygen attached) have a distinct fruity smell, and in fact they are commonly used in sweets, as well as being the sources of flavour in many fruits.",
"flavor is the presence of a chemical. if you just synthesize the chemical and put into the food, then it's artificial flavor. if you take the natural food and extract the flavor bits, then it's natural flavoring. if make citric acid (the sour in alot of fruits like lemons and limes and oranges) by taking it out of lemon juice, then it's natural flavor. if you make citric acid by fermenting by giving the fungus aspergillus niger tons of sugar, it'll gobble up all that sugar and poop out citric acid. now this citric acid has nothing to do with being extracted from fruit. it's artificial flavoring."
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7ej14l | Difference between microbiology and molecular biology? | Biology | explainlikeimfive | {
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"a few orders of magnitude. to my understanding Microbiology is about tiny organisms like bacteria, maybe algae, viruses, etc. (size roughly 1/1 000 000th of a metre) Molecular biology goes about 1000 times smaller and looks at how the various proteins interact, how cells communicate using certain chemicals, how DNA works, etc. It's essentially \"Nanobiology\"."
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7ej40i | Why did Mao and Stalin kill all those people? | Other | explainlikeimfive | {
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"Mao killed people almost inadvertently. He knew what he was doing but it was different in the sense that he wasn’t pulling the trigger, sending the orders for their executions, etc.. Mao wanted to compete with the United States and become one of the main “super powers” of the world. This was known as the Great Leap Forward. His main goal as leader was to have the most exports, have the most technology, and pretty much be one of the best in every economic sense you can think of. This is in turn what created the fallout of the chinese economy and a famine that killed most of the people that “Mao killed”. He was exporting most of the resources farmers and marketplaces had acquired, not bothering to leave any for his own people. He was trying to export more goods than the United States and Japan were, and in turn had nothing left in China for his people and they began to starve. In this process he killed over 15 million people through starvation. The Campaign to Suppress Counter-revolutionaries involved public executions that targeted mainly former Kuomintang officials, businessmen accused of \"disturbing\" the market, former employees of Western companies and intellectuals whose loyalty was suspect. Another million chinese were likely killed in land reform (the taking of their land to give to poorer peasants in efforts to reduce economic inequality) and 800,00 in the campaign to suppress counter revolutionaries. Mao’s agenda was to put China on the map and create a large super nation to compete on the same levels with the US and Japan, and wished to do this as fast as possible. This in turn was his motive and created the result of China for years to come.",
"Both are a bit questionable as to whether they should be called mass killings on par with Hitler. Both Hitler and Stalin imposed policies that lead to very many deaths. Because the deaths were somewhat predictable they are today called mass murders by people on the right (and some historians). We should be careful in expanding that application in this way as it may well come back to bite us. Until ObamaCare f.ex 45,000 people died every year in the US due solely to a lack of access to healthcare. Apply that math to the last 100 years and you end up with 4.5 million deaths (just used as an example of methodology and doesn't adjust for the lower population through those years). Add to that the deaths from our lax gun policy and you end up with millions more. Add the War on terror, the Southern Strategy, slavery, Jim Crow laws, lynchings, welfare cuts aimed at African Americans, etc and suddenly the US government may be up there among the biggest mass murderers of all time. However, returning to your question as to history: Both Stalin and Mao were mainly deaths tied to implementation of their version of communism. Stalin did actively execute people who were upper or middle-class, and these count regardless of methodology. Most of the deaths, however, are less direct, for example when he decided to get rid of the wealthy land owners in Ukraine and did so in a rapid way, without taking steps to ensure the farms would be kept going. The effect was that 3-5 million died of starvation in Ukraine. Mao was similar. When he came into power his first focus was the Culture War where he executed the wealthy and intellectuals. Next he shifted his focus to the Great Leap Forward - a program aimed at lifting up China. The main bulk of deaths attributed to Mao is due to his failed farming policies. As a part of the Great Leap Forward Mao decided to abandon the traditional farms and instead imposed mandatory collective farms. In parallel Mao implemented increased industrialization, taking farmers from the fields and into factories, which added to the problem of starvation. Ideology is a dangerous thing, and leads to people making stupid ideas that cost people lives. Mao and Stalin are two examples where ideological fervor does great harm to a nation and ordinary citizens.",
"They all have similar economic motivations. Reduce your population, reduce poverty. Ease the strain on food production back to a more manageable concern. They didn't really care that it was causing people to die, it was just a means of turning the economy around (trying to at least). Edit: /r/askhistorians would be a better place for detailed answers.",
"Can't speak about Mao, but as Ukrainian I know thing or two about Soviet Union. Some things might apply also to Mao as authoritarian regimes might have similar motivations for all kinds of oppressions. TL;DR kill everyone who threatens your power or who look like he would. It's easier if you genuinely believe that you are infallible and those who disagree don't deserve to live. First, it's not really correct to address mass murders only to Stalin. He is indeed notorious example, but he wasn't the first nor the last person in USSR responsible for murderous politics. And in different periods there were different excuses to kill people. USSR's history started with Lenin and his friends, and the big part of the ideology behind revolution was that evil capitalists and feudals are oppressing the working class. Therefore, all wealthy people should be killed so the working class would be it's own master. It also wasn't just a revolution, there was a civil war. For simplicity, between communists (red army) and ex-imperialistic forces (white army). White army was very cruel to communists and those who supported it, it was called the \"White Terror\". In response to it, commies started their own \"Red Terror\" which brought the violence to the complete new level ([more here]( URL_0 )). So the first reason was wiping out those who were unwelcomed in USSR - rich people, and ex-imperial political and military elites. It is still not clear how many people were executed during this period, estimates vary quite significantly, but anyway, it's up to 2 million victims. For the second part we need to remember that before USSR there was Russian Empire. And as it happens in empires, especially when they fall, there are nationalistic movements advocating ideas of independence. Ukraine declared independence in 1917, but by 1920 was conquered back by USSR. After that, there were several famines on the territories of former Ukrainian Republic plus areas with significant population of Ukrainians, like Kuban. In 21-23 and then, most brutal one, referred as Holodomor, 32-33. Again, estimates vary, but at least 2.5 million Ukrainians died in Holodomor. Ukrainian historians often say that that was a measure to pacify Ukrainians. Russians tend to say that it was because of the drought, and Ukraine was not the only region suffered from famine, but that's just small part of truth and a big chunk of manipultaion. Even leaving pacification version aside, food was harvested in Ukraine to distribute between areas more affected by droughts, and also wheat was sold to the West to buy technologies, that was so-called \"industrialization\" period. Not the bad plan by itself, but the economics was planned back in USSR, and farmers had plans to execute. And those plans were just unrealistic. And the punishment for not executing the plan was that NKVD would come to your place and take whatever you have in order to cover the \"shortage\" of the plan. More to this, there was so called \"Law of Three Spikelets\", by which stealing the grain was the capital offense, punishable by death or 10 years of prison with confiscation, and the gleaning was considered stealing. Also, grain was often stored in premises not designed to store food, so lots of grain ended up being completely spoiled. So, that's the second reason - inadequate measures to get some industrial powers and suppress nationalistic movement. ([more]( URL_2 )) Also, for suppressing reason - there was so-called \"Executed Renaissance\": about 200 ukrainian writers and artists were repressed and were shot or died in camps. During the WWII there were also cases when soviets were showing unnecessary cruelty in order to make German's life harder on the occupied lands even though collateral damage to civilians was sometimes bigger that actual harm to Nazi troops. One notorious example is explosion of Dneproges dam, they did it before retreating, without notifying anyone. The wave released after explosion killed tenth of thousands unsuspected citizens. And before and after war there were quite brutal repressions on newly obtained lands - again, to suppress any nationalistic movements and pacify people. After occupying Poland with Hitler as allies, soviets killed more than 20 thousands poles, imprisoned during invasion, mostly officers of army and police, for being \"enemies of the soviet authorities\". Also, mass population transfers. E.g. Crimean tatars were declared collaborants (the whole nation) and deported to Uzbekistan. Same in all the regions soviets occupied - mass deportations were one of the means of suppressing nationalism by dispersing the nation. These are not direct killings, but conditions of transportation were terrible, and up to 25% of Crimean tatars died due to the deportation or shortly after - and that's by official soviet sources. The part of repressions usually associated with Stalin, I think, can be assumed as extension of the Red Terror, and, speaking of reasons - they were rather common for all totalitarian regimes. If there's totalitarianism, only one point of view can exist. But that's not natural for human societies, so totalitarian regimes build oppression machines to suppress any oppositional thoughts. And for Stalin's repressions: if you use those people as slaves - you can kill two birds with one stone: first, you get rid of those who don't agree with you, and second - they will work for free where no one else would work for money: Siberia is rich with oil, gas, gold and diamonds, but it's extremely cold there and no infrastructure. Famous GULAG was a large network of labour camps, but the conditions in most of them were so dire that they were no better than Hitler's death camps, excluding gas chambers. There's a collection of short stories, \"Kolyma Tales\" by Varlam Shalamov, I don't know if it was translated into English and published, but I recommend you to find and read it as it is documentary stories by person survived in GULAG (Some of these stories can be found [here]( URL_1 )) Also, USSR was very violent when it came to any protesting activities. Violent suppression of protesting/separatistic/democratic movements, like in Budapesht, Chechoslovakia or Vilnius. In 1962, workers of Novocherkassk were shot on the streets for protesting against raising food prices and then government kept this incident as secret.",
"It really depends which \"killings\" you're referring to. For Mao: - The Chinese civil war was a period of massive instability. People were killed largely as a matter of trying to win that conflict. - Afterwards, the \"cultural revolution\" and \"great leap forward\" were respectively attempts to destroy the old imperial Chinese culture and replace it with a new, distinctly modern one, and an attempt to rapidly industrialize and get China on the path back to being a world power again. It's the second category of deaths that I think you're mainly referring to. /u/Absobloodylootely does a good job of explaining a lot of the rationale. One thing I would add is just the answer to \"why did that many deaths seem worth risking?\". With Stalin, under the purges and holodomor, the motivations were a little more straightforward - he was eliminating enemies. The purges were about political enemies within the state, and the holodomor was about privileging ethnically russian citizens who were seen as more loyal over ethnically ukranian citizens who were seen as less loyal. With Mao, a lot of the people were still ethnically Han Chinese, and a lot were even fairly supportive of him. So why risk their lives? The crucial point is rooted in the ideology resulting from the Chinese [century of humiliation]( URL_0 ) - in a sense, \"humiliation\" is really too mild a term for it, since western powers invading and occupying china were responsible for death and destruction on a scale that's difficult to even comprehend today. In that century, you had 2 opium wars that flooded the country with drugs, destroying its population and undermining government power, the Taiping rebellion that killed up to 30 million people, The Sino-Japanese wars that killed up to 20 million, the Chinese civil war that killed up to 9 million (though partly overlaps with Sino-Japanese conflicts), the Dungan Revolt that killed up to 12 million, etc... (and that's only counting conflicts with a death toll in the millions during that century). It's not an exaggeration to say that between the 19th and 20th centuries, China saw more people slaughtered than just about any country has ever seen in human history, mostly in conflicts involving foreign powers. Besides which, that was starting from a perspective in the 18th century where Chinese culture considered itself the leading nation on earth. So the reaction by Mao and CCP leadership - having a willingness to sacrifice even massive numbers of people to ensure that history never, ever repeats itself, and to have China re-establish its position within the world system, the extreme measures at least make a bit more sense. Also, considering the methods Mao used - it was precisely the same mass mobilization and political rallying that killed millions in the Great Leap Forward that previously helped the CCP prevail in the Chinese civil war. Essentially, he was trying to industrialize using the tactics of a guerrilla uprising. Yes, Mao was absolutely wrong in the direction he took to achieve those ends in the Great Leap Forward, but given the country's history for the preceding century, and the past success of those same leadership methods, there's a reason people were willing to follow along that far. That certainly doesn't excuse the abuses by any means, but at least it puts them into some kind of context."
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7ej5qq | How does observation collapse the wave function? | Is it a photon bounching off that changes the results? | Physics | explainlikeimfive | {
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"\"Observation\" in a scientific sense requires interaction with the thing being observed. You need to bounce something off it and the measurement inevitably changes what you measured in some way. The actual observation of the data by a mind is irrelevant."
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7ejg6h | Why some people can grow beards and others can't? (even if people seem to be the same build ie similar testosterone) | Biology | explainlikeimfive | {
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"You not only need testosterone, but also the right density and sensitivity of androgen receptor on your face (which testosterone docks onto) to get your facial hair growing.",
"Some people have neural fibers in their skin ganglia that responds to stimuli from the environment. That and certain genetic markers allow for folices deep within the skin to penetrate the surface. Prolonged contact with salt water actually helps healthy beard development because the salt water acts as an acid while your skin is so fucking basic they fuck each other",
"They may have a low sensitivity to testosterone or they may have been born with few bulbs in their face.",
"DHT is actually what causes a beard to grow, not Testosterone. High DHT means faster growth, and more hairs. In order to create DHT, your body needs to use up Testosterone. Usually you'll have an amount of DHT in your blood equal to 10% of the amount of Testosterone, but some people produce more or less. Genetic factors can change the amount your body makes, so some people might have 20% DHT compared to T, or 5%... etc. Different amounts are also created in different parts of your body, so you could have normal DHT levels in your prostate, but low levels in your face."
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7ejjfc | Do animals ever get sick of eating the same thing everyday? | Biology | explainlikeimfive | {
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"Animals don't necessarily have the imagination necessary to understand that there are other options available and that a substitution would be nicer. However, it would be very hard to test this. Animals definitely have preferences if presented with two different foods together, after all. You can see that in pets; my dog will pick through kibble to get treats put in her bowl. But, many cats and companion birds are notoriously difficult to switch to different foods and treats. So how would scientists test boredom? [This article]( URL_0 ) talks about boredom in animals in general, and some of this difficulties in determining it. You sent me into a bit of a wormhole so here's [another]( URL_1 ) .",
"Are you talking about domesticated animals or wild? Wild animals have a varied diet based on what ever they could forge each day. My anecdata says yes for domesticated animals. Personally my dogs rarely eat the whole 2 cups of food I give them a day, however when we switch their food, they would eat up to 20 cups a day if I gave it to them. Similarly they can get bored of playing with the same toy everyday, it would be easy to see that extend to food as well."
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7ejmmb | What exactly stops our bodies from defecating and urinating as we sleep? What acts as an "alarm" that jolts us awake when we do need to do these things? | Edit: Jesus, this blew up. Instead of replying to everything (of course I'm going to try to get to a lot), I'd just like to say thank you to the massive knowledge drop I've received. I did not expect so much information about how my body is basically an automaton. Super cool!! Thank you guys! | Biology | explainlikeimfive | {
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"So your body has these muscles called internal and external sphincters. They act like these rubber bands around your rectum and your urethra (where pee comes out). You can control the external sphincters but can’t control the internal sphincters. The feeling that you need to pee or poop comes from the internal sphincters saying “hey we need to go” to your brain and then they relax/open to let said pee or poop out. The clinching feeling when you’re trying to hold it in is your external sphincters, which you can control. When you’re sleeping/awake these sphincters are constantly contracted/closed but if the internal sphincters relax/open, then your brain will wake you up because you have to go.",
"Anti-diuretic hormone (ADH) is certainly a factor. ADH levels are supposed to increase at night to prevent urination during sleep. Sometimes this system takes a while to develop in children, making bedwetting more likely [1]. Similarly, disruption of normal daily fluctuations of ADH can lead to bedwetting in the elderly [2]. Alcohol inhibits the release of ADH by the pituitary gland, causing increased production of dilute urine and potentially leading to dehydration and/or bedwetting [3]. [1] URL_0 ; [2] URL_1 [3] URL_2 Edit: Cortisol is the primary \"alarm\" hormone, but cortisol doesn't really have anything to do with urination. The amount of urine produced is controlled ADH, which doesn't really have anything to do with waking up. Urinary retention depends on the coordination of these two hormone levels (high ADH low cortisol at night, high cortisol low ADH during the day).",
"REM sleep puts your body into a paralysis when the cycles that tells you you are hungry or need to go to the bathroom swing around. Prevents you from waking up or having your body go through it’s natural awake rhythms. When you are intoxicated your body can’t go into REM sleep as easily which is why you have a terrible sleep and can sometimes wake up to a lovely wet bed! Source: a lot of psychology and neuroscience courses",
"The bladder and rectum have stretch receptors in them that are a “warning” (alarm) and let your conscious mind know that your ready to go. Both your urethra and rectum have muscles under your control that allow you to relax and go.",
"There is a hormone called ADH (antidiuretic hormone) that reduces the amount of urine your kidneys produce while you sleep. That is one of the reasons kids wet the bed, however adults tend to be able to hold it, it isn’t fully developed until you are older.",
"i am not specialist like guys in other comments but you don't shit yourself when you are awake neither you go to toilet and you give a command to your body \"Let it go, let it go, Can't hold it back anymore\" also when there is too much stuff in your body \"Let it go, let it go, Can't hold it back anymore\" is executed without consent (for example comma)",
"How would this relate to a kid that wets the bed?"
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7ejnj7 | Is the huge dust from an massive building implosion (like the Georgia Dome in Atlanta this week) harmful to humans? | In case you missed it, here is a visual of what the implosion and resulting dust cloud looked like. URL_0 | Biology | explainlikeimfive | {
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"Yes. All dust is harmful with enough of it. However, this type of dust generally settles quickly and in a small area, which means the workers will be wearing PPE. The farther you get from it, in time and space, the less there will be. If you're sitting in a closed room 2 blocks away, there will be almost none coming in."
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7ejpn8 | Picasso and Cubism. How does Cubism work? What's the idea behind it? | Other | explainlikeimfive | {
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"Let's just begin with an understanding that the perspective on a typical painting is seeing the subject through a window. The frame is like a window frame, and the canvas is like the glass. This takes a three dimensional image and transfers one possible angle of viewing onto a two dimensional medium. For Cubism, imagine the subject is inside a glass box. Depending on which flat side of the box you look at the subject, you get a different perspective. If you painted each of those unique perspectives on each of the glass sides, you'd have a two dimensional representation of that unique perspective on each glass side. Now, if you took the box apart, and started started layering those sides to show more than one perspective at the same time in a flat image... you're pretty close to understanding cubism."
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7ejpou | Why do small, superficial wounds heal faster on certain areas of the body, like the mouth, than in other areas? | Biology | explainlikeimfive | {
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"The mouth is special for two reasons, one it contains certain chemicals that aid wound regeneration and saliva, saliva provides moisture, cleaning/defence and more good chemicals. In the rest of the body, it differs, certain places in the body have worse blood flow, which inhibits wound regeneration. The dimensions of the wound are important too, if it’s a cut ; it’s easier to heal, as less time/material is required to make a ‘block’. If it only perforates the skin layer (epithelium) and not go further it is also preferable as epithelium grows quickest, if it perforated deeper, into the connective tissue, where you have Nerves and blood vessels, regeneration is gonna take longer.",
"EGF, epidermal growth factor and other growth factors. Antibacterial compounds some as secretory Ig A, lactoferrin, lysozyme and perioxidase and others, by helping in cleaning, the entire process is faster.",
"Your skin has many layers. On top is a bunch of dead skin that has been keratinized (dried and hardened) to be a protective layer. Underneath are cells called stratified squamous epithelial cells. Translation: layered squishy-brick skin cells. As the outer layer of living skin these cells are designed to take the bulk of the abuse for your body. Part of their design allows them to be regenerated very fast. In humans, we have special areas covered in lots these cells that allow us to perform many necessary functions. The openings and exits (mouth, anus, vagina) of the human body are generally covered in extra thick layers of these cells, which regenerate extremely quickly. Source: human anatomy"
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7ejt7j | Entities - Databases | I'm starting a computing course and cant get my head round the concept of entities in databases. If i had a flat database that i needed to turn into a relation database with the headers: Surname, Firstname, Venue, Price, and Length of stay what would the entities be and why? I'm pretty sure 'Customers' would be an entity with Surname and Firstname as instance of the entity but what would the other be? Thanks! | Technology | explainlikeimfive | {
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"An entity is a thing. You make tables in a database out of entities, each row ideally represents an individual entity. In your case, what is the table storing? Customer information? Order information? Venue names? It's not clear. Ideally you'd have a table to represent Customers, Venues, and Orders, all are \"entities\". So you'd have a table, Customers. Customer ID - Last Name - First Name - Contact Info, etc. a table, Venues: Venue ID - Venue Name and a table, Orders: Order ID - Customer ID - Venue ID - Price - Length of stay The benefit of a system like this is if you want to change a customer's contact information (or name) you do it in one place. Same if you want to rename a venue."
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7eju6h | Why does antimicrobial treatment start only after blood cultures are negative? | A repeating theme I see in medical treatment is this concept that the first day of treatment is the first day negative blood cultures are obtained. I've seen this in relation to antibiotics as well as antifungals. From Tresch and Aronow's Fifth Edition of Cardiovascular Disease in the Elderly: "The first day of negative blood cultures 'starts the clock' for the planned duration of antibiotic therapy." | Biology | explainlikeimfive | {
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"Be warned that I'm greatly simplifying this. Usually, blood cultures help guide appropriate treatment of an infection, if you know what the bug is and what it is sensitive to, you can switch to a more effective antimicrobial or a more narrow spectrum (one that is effective on fewer bugs) antimicrobial (to reduce issues related to resistance). The quote from the book you shared, is referring to treatment of infective endocarditis (IE), which is a bacterial infection collecting around a heart valve. Treatment with antibiotics for this usually takes time (weeks). First day of negative blood culture \"starts the clock\" means you start counting after a negative blood culture is achieved to determine the recommended extended duration (usually weeks) of treatment. You would have already started treatment right at the beginning of diagnosing IE, and this is just a way to decide how many more weeks of treatment the person needs. Too short of a duration and the person might not be well/still has a high chance of complications from the infection/might get the infection back. Too long and the person might get higher chance of bacterial resistance/complications from antibiotic treatment etc."
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7ejuf9 | What is a medium? Why is air and water mediums? | Other | explainlikeimfive | {
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"Mediums are anything that stuff can travel through/communicate through. Air is well.. air and sounds travel through it (which are really vibrations traveling through air molecules). Water is a medium because lots of complex chemical reactions can occur in an watery (aqueous) environment. This has to do with water’s polarity. Water and air don’t always have to be the mediums, solids are mediums, they can actually carry sound waves better than air"
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7ejuuz | How do they stop a large gas main fire? | Other | explainlikeimfive | {
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"Depends on the intensity of the fire. Generally they shut off the flow of gas further up the system. Letting the remaining fuel burn off, cooling it with water or foam and sealing the well. There are methods to shutting off fires at oil wells which can involve the use of explosives or other methods of capping the well. URL_0",
"> Just got me wondering how they keep it from going back up the line. Fire needs three things to continue: Fuel, oxygen, and heat. There's no oxygen in the gas line, so fire can't burn there."
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7ejziv | When food goes stale, does it also become less nutricious? | Chemistry | explainlikeimfive | {
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"Generally, yes. It isn't just \"staleness\", but any process that takes food away from its original composition makes food less nutritious. It depends on the food as well, as things like fruits and vegetables rapidly lose their nutrition after they are cut or processed. A lot of the healthy nutrients are \"trapped\", in a sense, inside the less reactive environment that the food provides. There are molecules (enzymes) which interact inside fruit and vegetables which seek to preserve the health by various processes, such as bruising. Bruising, cutting, frying or anything else causes these responses, which changes that stable environment; consequently using the nutrition reserve. Not all nutrients are lost this way, and it is usually specific to the vegetable, fruit, grain, or whatever. Some nutrients, such a minerals, can stay reasonably in-tact during these processes. Vitamins and proteins are often the first to go, as those are what the veggie/fruit/grain uses to protect itself, along with other organisms taking advantage of this \"broken\" environment. When we look at why we taste as we do, it is to extract as much nutrients from our food as possible. Stale, rotting, or processed food are far down the path towards \"unsustainability of their microenviroment\", or \"potentially less nutritious\" which is determined by our brain to not taste as good."
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7ek44w | Why do police officers not always wear kevlar as an occupational precaution? | Other | explainlikeimfive | {
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"> Seems like there would be no downside Spoken like someone who's never worn kevlar. Vests suck. They are uncomfortable, stiff, and sweaty. While most departments require them for patrol officers, officers who can get away with not wearing them sometimes don't. Simply because they judge the inconvenience of the vest to be not worth it. In many positions the likelihood of ever being shot at is as near to zero as it can be.",
"To piggyback on what /u/rhomboidus said, the biggest reason is that they're uncomfortable and restricting. The overwhelming majority of police officers will never have a live round fired at them. Even for those that have been fired at, there are very few who have been saved by a vest. In 2017, [41 officers have died nationwide from gunfire]( URL_0 ). That's fewer than the total number of officers who died from vehicle-related causes. Without trivializing any of the deaths, it's fair to say that gunfire related deaths aren't a widespread issue. As a whole, [being a police officer is a safer occupation than working construction]( URL_1 ). When those numbers are put into perspective, it's easy to see why police officers would choose not to wear a vest. Sure a vest might make them marginally safer, but the limits it places on an officer's ability to move and carry out other duties comfortably aren't necessarily worth it relative to the risk of getting shot. Another thing to consider is that bullet proof vests aren't completely effective. Depending on the rating, they will stop most pistol rounds, but they're generally not effective against most rifle rounds. Further, they only protect the (important) chest and abdomen area, leaving the wearer still vulnerable to getting shot in other areas. Even if a vest stops a bullet, the wearer can still be subject to serious injury. While I do not have the concrete statistics to back it up, it stands to reason that proper training (and adherence to that training) does much more to keep an officer safe than a vest ever could. If an officer ever reaches a point where they're depending on their vest to save them, they have much more to worry about than whether or not they're wearing something that can stop a bullet.",
"My dad has been in law enforcement for 26 years and has worn his vest every day. He even wears it when we go shooting because \"it feels wrong without it\"."
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7ekae0 | Why was salt so valuable? Couldn’t coastal communities just evaporate ocean/sea water? | Other | explainlikeimfive | {
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"That works fine for the coast, but what about communities that are 500 or 1000 miles from the sea? Plus, salt was used for a lot of things, preserving food, tanning hides, etc, so it was much more in demand than it is today. Also, it was relatively easy to weigh, transport, and store, so it made a useful standard commodity to use as a sort of currency. Not really any way to counterfeit or adulterate it, so that was another good point in it's favor.",
"They could, yes. And people did have access to salt from that method and others. However, may people didn't live by the coast, which meant you'd have to transport the salt you gathered that way over great distances. And second, it requires a lot of time and space to get any amount of salt that way. Think about it - you don't want to lose all your salt when it rains, so you'll need a roof. Evaporation requires surface area, so you'll need wide, flat containers. There are solutions to this, but they're labor intensive to set up. So salt remained valuable."
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7ekdgl | We do we feel tired after thinking/focusing for a while? Are we expending energy in our brain? | Biology | explainlikeimfive | {
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"Yes. Your brain and the cells inside it are little factories. They make and sell goods, as well as talk to other factories to make sure everyone is on task. A byproduct of factories is waste, and all of our cells produce it, including our brain. When the cells are asked to work harder, they take in more energy from your diet (sugars/carbs/proteins/fats, etc), use it to do work, then a bit is left over which - to most cells - is toxic or unwanted. A lot of toxic waste can be dealt with (such as hydrogen peroxide formation and degradation), but there will always be stuff left over to get rid of. The brains \"city sweapers\" and \"road cleaners\" can only work so fast, and can't keep up with the waste from these factories who were told to work overtime. The result is that your brain tells your body, when too much waste exists, \"ok, stop, i need to be cleaned and to recover\". You expend energy when you're focusing, and your creating problems which take time to fix, no two ways around it."
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7ekgoc | Why is lead used to protect against radiation? | Is lead the only metal that can stop gamma rays? Why is it so commonly used when it’s toxic itself? | Physics | explainlikeimfive | {
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"Because it is dense. Lead isn’t the only thing that can be used. To protect yourself against gamma radiation you want to put a lot of electrons in between yourself and the radiation source, and this is best done by putting something dense between them. You could just as well have massive walls of wood to achieve the same effect, but lead walls would be thinner and easier to handle as a result of their density. Ironically enough, this also means Uranium is a better shield against gamma radiation (while Uranium does produce alpha radiation, it produces pretty much no gamma radiation, alpha radiation can be stopped by a piece of paper). Lead of course is far cheaper but sometimes Uranium is the better choice.",
"> Is lead the only metal that can stop gamma rays? Why is it so commonly used when it’s toxic itself? Lead is chosen as a radiation defense because it is dense and cheap. The nucleus of lead atoms has a lot of protons and they are relatively tightly packed compared to something like concrete. Lead is toxic but isn't really handled directly often enough for that to be a concern. If we had complete freedom of materials then gold might be a superior choice but expense is an obvious detractor.",
"all materials can stop gamma rays...EVENTUALLY. The advantages lead offers: - it is very dense (heavy for its size), this leads to it absorbing/stopping gamma rays faster - it is really cheap compared to similarly dense materials - it isn't radioactive on its own and (not 100% sure) doesn't have any \"dangerous\" isotopes when it takes in the energy from the gamma rays. How gamma (and alpha/beta) rays are stopped is simple: they need to \"hit\" atom cores to get absorbed and stopped. in gases (like air) there are only very few atoms per cubic metre compared to liquids or solids. And those atoms are usually of lighter materials. you can also stop gamma rays with water for example. or wood. works fine. just takes a lot more because Carbon, Oxygen and Hydrogen are a lot lighter than Lead and have smaller and fewer atom cores per cubic metre. So it's less likely that the tiny gamma rays will hit one of theirs. So you need to place more. Say like if you were to shield something with wood you'd need 5 or 6 times the thickness (numbers might be off a bit). or 4-5 times when using water. this means you need more space, moving becomes more difficult, etc.",
"lead is effective and cheap and abundant. the heavier elements beyond lead are not cheap. they're mostly very very rare elements compared to lead.",
"Lead is very dense, and very plentiful; most of the heavier metals can stop a lot of radiation, but lead is significantly less toxic than a lot of other heavy metals, and is cheaper and easier to obtain, vs gold or silver. You can block radiation with other materials, but it needs to be thicker; lead just makes for the sweet-spot for blocking radiation, able to get enough of it to make shielding, and it isn't too hard to work with."
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7ekn2p | in light of the current US political climate, how is America still tied to a two party system? | Other | explainlikeimfive | {
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"The US uses a first past the post winner take all voting structure for our representatives in most States, and for the Presidency. As such that means that you will always have a primary party that wins often, and their primary challenger. Now these positions can and have changed over time (the Republicans replaced the Whig party for example) but when you have a winner take all system it will always devolve to having 2 parties. It is also important to note that the parties are not an official part of our government in the US like they are in the UK or other similar Parliamentary systems. In the US they are civilian organizations that attempt to organize voters with similar opinions.",
"Our voting system is a large part of it. Instead of being a matter of which candidate gets the most vote, most elections require a absolute majority (50+ percent of the total vote). If two parties run a similar platform, they can end up splitting votes, and neither party gets a elected candidate.",
"> ...with smaller parties providing balance to prevent extreme policy shifts. The other replies about the two-party system being a result of first-past-the-post voting are great, but I wanted to point out that in general, a two-party system prevents extreme policy shifts better than a parliamentary system with runoff voting. It doesn't take that large of a share of the population behind some radical third party to significantly influence a parliament with runoff voting. On the other hand, with a two party system, both parties have to appeal to a very broad audience if they are to gain support of a majority of voters. If anything two-party governments are sluggish to respond to changing views.",
"Both major Parties absolutely agree that it would be very much better if there was no third major party. They can't agree on much, but they can agree on this."
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7ekuzt | Prions and prion disease; how can a protein be infectious? | I am really struggling to understand how a protein with no RNA or DNA can bring about disease! | Biology | explainlikeimfive | {
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"text": [
"Ok, here we go. This is my first ELI5, so I hope it helps. Feel free to critique anything. Think of DNA as a recipe. You have all kinds of recipes: cakes, pies, fruitcake. For the rest of this example, we will use cake recipes. There are set instructions, but you can also tweak them a little (strawberry cake, vanilla cake, etc..) But if you substitute something important for something else (sugar for salt) or completely mess-up a step (Baked at 1000 degrees vs. 400 degrees), then you have a disgusting mess that will probably make you sick. Now to transfer it to the body: DNA is a template for RNA which is then a template for a Protein. Proteins are then modified and/or folded to meet the exact requirements that the body needs. If a protein is misfolded (as many prions are) then the body goes \"Hey this is a disgusting mess, I can't use this!\" and thus you have a prion. These misfolded proteins then accumulate and can wreck havoc on your body (typically your brain).",
"Prpc (the prion protein) misfolds, then through a currently not really known yet mechanism they cause other prpcs to also misfold. These misfolded proteins aggregate, similar to the Tau protein in alzheimers resulting in \"plaques\" that the body cant remove well because they're in the brain. These plaques cut off signals and nutrient supply resulting in holes in the brain and swelling (spongiform encephalopathy), resulting in neural degradation, coma and finally death. We have not yet been able to figure out how to treat the plaques or fold the proteins into their working shape."
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