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cjzz9w | Why is it funny when people fall / get hurt? Is it a nervous reaction? | Most the time its not. Its when they get back up its a nervous relief | c9c05714-2fc4-444f-8c81-f8296eeadb63 |
ck0s22 | How did last names stick? | There are different kinds of last names. Job based, Location based, feature based, familial (son of, daughter of, descendant of, etc), and assigned.
For Job based names you took the name of the profession that you had. If you changed profession, then you would generally change or amend your name to reference that. Most professions were passed down father to son, but apprentices were also a thing and they would change their name from what they had as a child when they took up their trade.
Location based. Names like Hill, Dale, German names with "Von", Spanish names with "De", etc are names that are location based. John Hill would be a very local oriented name meaning John who lives on the Hill. The last name Von Bismark means someone "of Bismark" which means someone who is from the city of Bismark. These would commonly change when you changed where you live, though the "Von" and "De" names changed less often as they are more origin based.
Feature based names are things based on someones features. So Little would be attributed to someone who was small (or ironically to someone who is huge), the last name Green could be given to someone with green eyes. Black could be given to someone with black hair or skin. Etc. These names could change from one generation to another.
Familial names. Some names are based on the name of your father. So John has a son named James. James could be called James Johnson. James then has a son named Peter, he would be called Peter Jameson. So on and so forth. In English we tended to stop the trading of names after a time, and just stayed on one for each generation but other cultures such as Iceland still switch every generation (and they have a different variant for son's and daughters). O', Mc', and Mac in the Gaelic/Celtic cultures means descendant of. They would be based on some famous or "famous" ancestor that the family found to be important.
Assigned names were typically the kind taken or given to nobility. This name was likely the first to be passed down unchanged. | 0970c8c6-a8f5-454d-8abc-8c4137c20639 |
ck11zw | How do we know what music sounded like in ancient cultures? | **ELI5:**
We often know what their musical instruments sounded like.
Ancient peoples sometimes left clues about how their instruments were made. Then, a smart man can make a copy of the instrument - and play it! Sometimes, musical instruments are buried with people, and we can make a copy. Sometimes, an old type of instrument is still in use today. Drums are very old, and very common - you know what a drum sounds like. Flutes are very common, too. If you know the size, shape and makeup of an instrument, a craftsman can probably make a decent copy. Making old style musical instruments is a hobby for some people, and a job for others.
What I do not know is what *tunes* were played - another poster may have the answer to that question. | 9b0881f9-7baa-437d-91dc-d2a2b4740a8a |
ck18cc | How does cryogenic preservation work for both sperm/eggs and entire human bodies/entire human heads? | The short answer is that the process is very similar, but the results are night and day. If you freeze a head, it's *not* coming back using any conceivable technology; it's done. In addition to the reality of widespread cell depolarization and death in the brain, what actually dying doesn't finish, the process of freezing will. Even with "antifreeze" added, you're still talking about huge sections of tissue being lacerated by ice crystals. Ever freeze and then thaw out a steak? See the mess of liquid it's sitting in, and how it's gotten a bit mushy? Yeah.
Sperm and eggs are easier because they're both single cells, are extremely simple, and have a *huge* surface area to mass ratio. As a result you can literally flash freeze them in an instant, which just isn't possible with something like a whole head. Even then, you don't recover anything like all of the sperm or eggs, but you don't need to. Losing a bunch of sperm in particular isn't a problem, you're freezing millions of them after all. A brain however, is kind of a delicate organ containing many billions of cells, the arrangements and states of which *are you*. Losing a bunch of them to the process, not to mention the ones you lost to actually dying and transport to the facility, is just too much even if you could be thawed without the "mushy steak" problem.
Finally, while not a technical hurdle, it's worth considering that eggs and sperm are stored by the people who "made" them, and who value them highly. They're not intended to last forever, and wouldn't, and they're something that people who have a connection to them want to recover and use. A frozen head on the other hand? How many generations would need to pass before no one is left to give a crap about it? What future society is going to prioritize reviving a bunch of primitives with more money than sense, and no connection to any living soul? | 99f3ed72-f0b4-487f-a9af-fb9ed9bf067c |
ck1ju4 | How is looking up a hash table O(1), but looking up something in a normal array still O(n)? What's the difference between a hash table and a list of hashes? | Accessing an array is O(1). Perhaps you mean searching for something in an array. If the array is ordered then searching is O(log(n)). For an unordered array the search is O(n).
Hashing means taking the search key and processing it in some consistent way to produce a single number which you can then use as the array index, i.e., the storage location in the array. If the keys are words then a simple hash would be to add the ASCII values of all the letters in the word so you'd find the entry for the word "A" in array slot 65. No searching is required, so the time to find an element doesn't depend on the size of the array (though it does depend on the size of the key).
Obviously there are problems with the above simple hashing scheme. The words "ab" and "ba" would be stored in the same slot. The array would need to be very long to have space for long words. Read up more on [hash tables](_URL_0_) to find out how these and other issues are handled. | 29454bdb-aace-4941-a0e5-55d86d403879 |
ck1jxz | Why do ham and bacon taste completely different when they come from the same animal? | There are a few of different reasons. One is the fat content, the second is how the meat is prepared, another is the location on the animal that the meat comes from.
You can even taste that last factor with other meats, like chicken. Compare the taste of a chicken breast (white meat) to a chicken thigh (dark meat). Even if they are prepared the same way, they will taste different because of the basic differences in the meat. | 6a387357-260a-48a4-b9d9-69ebe18b3c84 |
ck1lgd | Are daily vitamins really that necessary to take? | Some vitamins are not water soluble. For instance, you can take a great deal of vitamin C. You’ll just pee it out. (Extreme doses can cause some discomfort.) However, vitamins A,D,E and K along with others can be very dangerous when misused. Overdose can occur and can have issues from skin discoloration to death.
The MOST anyone should need, unless recommended by a doctor, should be ONE multivitamin per day. Chances are you’re getting enough from 3 meals, but if you have bad eating habits, 1 per day is plenty.
EDIT: Some replies below mentioned some mild discomforts from too much vitamin C, so I’ve changed it from “as much vitamin C as you like”, to a “great deal of vitamin C”. | 73290e49-afc0-43f9-a209-d404cf18dc9a |
ck265w | What are neural networks? | Think of neurons as groups of people in different rooms of a building. Each person is very good at one thing and only one thing.
For example, people in the first room can only smell stuff. And each one can only tell you the probability of it being a certain thing. So one guy can smell and tell you that he’s 40% certain that it is coffee. Another can tell you that he’s 99% certain that it’s sugar.
So you walk in with an unidentified object, and the people in the first room tells you what they think it probably is.
Then you walk into the next room, where people can touch and tell you the probability of it being a certain material.
In the next room, the folks can lick and tell you the probability of it being the thing they specialize in.
But if the guy in the first room who specializes in poisons says this is 99% poison, the guy in the 3rd room (lickers) will pass on tasting it.
So each room gives you information that the folks in the next room use along with their own skill to decide how likely the object is whatever they specialize in.
As you make your way through more and more rooms, the accumulated probability information allows the people in the last room to make a fairly confident statement as to what the object is.
For example:
Room 1: “This is red in color (99% certain), orange (45%), green (4%)”
Room 2: “This is the size of a finger (95%), the size of a fist (6%), size of a football (0.5%)”
Room 3: “Smells edible (88%), smells like plastic (8%), smells like metal (1%)”
Room 4: “Based on all the info above and its taste, this is hot pepper (97%), lipstick (2%), a pen (0.2%)” | 3f30bb9f-3c4c-45cf-ab2e-b9667bd23658 |
ck2aay | Fourier Transforms | The Fourier transform allows a function to be broken down into a sum of sine and/or cosine waves (although e\^i can be used as well) of varying frequency and amplitudes. The goal is to use constructive and destructive interference from the waves to match the original signal as closely as possible.
The frequencies follow a fixed pattern (2\*pi\*n/T for n=0,1,2,3,...). The amplitude of each wave is the mean of the product of the function you're breaking down and the wave(1/T integral from 0 to T f(x)\*sin(wnx)dx). The specific frequencies and cosine/sine wave depend on each function. So as an example, look at the first 3 terms of a square wave.
1st: 4/pi\*sin(wt)
2nd: 4/(3\*pi)\*sin(3wt)
3rd: 4/(5\*pi)\*sin(5wt)
When all added together, they make an ok representation of a square wave. Adding more terms would increase the accuracy.
It's also really common to write the sin/cos terms as e\^i(n\*2\*pi\*x/T) because e\^ix is related to sin/cos waves because math black magic.
let me know if this helps. This was kinda hard without just writing equations
Edit: fixed error | a979a554-d55c-4e9a-9573-4b87f71967b4 |
ck2c5k | How do they balance planes that have uneven numbers of seats on either side of the aisle, such as 2-1 or 3-2? | Left Right balance is pretty much a non-issue. The people are all very close to the center of mass so it doesn't create much torque even if wildly imbalanced. Adjusting the trim flap a tiny bit on the end of the wing 10+ meters away results in significantly more torque.
Only front back balancing really matters because people in the nose and tail are far from the center of mass so if everyone is in the tail the plane will constantly want to pitch up | 6fe4e53c-d37c-4d8c-b8a8-ed9e179c4941 |
ck2eh1 | how low pain tolerance and high pain tolerance works | Pain is actually a very complex process. See, what you experience as pain happens in your brain, not your nerves.
Nociception (literally “harm perception”) is the process of a pain-sensitive nerve detecting a noxious stimulus and sending a message back to the brain. All peripheral nerves terminate at the spine, and pass the message on to the spine and up to the brain. But this doesn’t always result in “pain”.
Firstly, there’s what’s called the pain gate. This is a spinal mechanism whereby the spine shuts out one pain stimulus in favour of another - it’s why rubbing a wound lessens the pain. The spine is literally blocking a portion of the pain stimulus in favour of the less painful rubbing.
Secondly, there’s the brain itself. Whole PhDs have been written on this but the summary is the brain decides how much pain to feel based on context. Emotional state, prior experience, concentration and even language itself all have an impact on pain perception. It’s why an athlete might break their ankle but finish a race, while a person with a bad back experiences more pain when he’s having a bad day, or why injuries always seem worse at night when you have nothing else to focus on.
Pain tolerance is a mix of all these factors. Some people have alternative nociception pathways (there’s even a congenital syndrome wherein a person has none at all), some have excellent mental strategies for coping and some people literally just have better things to do. Some poor people have experienced something worse and can contextualise it differently. Pain is actually impossible to objectively measure - no two people will experience the same harmful event the same way.
Hope that helps. | f0dea596-61e4-4ccd-83a5-2f14b8fc3583 |
ck2i02 | Why is the water’s surface (in the swimming pool) see-through from above, but is not when looking from underwater? | What you're seeing is called **total internal reflection**, and it's something you learn about in physics class when you study things like lenses and optics. It all has to do with the angle between the ray of light and the surface of the water.
Let's pretend the water is perfectly horizontal, and doesn't have any waves or ripples on its surface. When a ray of light goes from the air into the water, the light is going to change direction. This change in direction is called *refraction*, and we say the light *refracts*.
When the light refracts, it always bends in a very predictable way. If the light hits the surface of the water at an angle, the water will always bend the light so that it is traveling closer to straight up and down. So, light comes in mostly sideways, and then hits the water and turns downwards.
If light leaves the water, the opposite happens. If it's going mostly straight up, when it leaves the water, it turns so that it's moving more horizontally. If you're in the water and tip your light so it's going more and more sideways, eventually you're going to find a point where when the light leaves the water it's going perfectly horizontally. If you tip the light in the water further from vertical, the light "leaving" the water will want to bend past horizontal and go *back into the water*. In other words, the light just bounces off the underside of the surface of the water, and goes back into the water.
Here's a video of a couple guys playing with lasers out on a lake demonstrating total internal reflection.
_URL_0_ | 7528d702-ea27-42a3-8fe2-195ef8c156df |
ck30lt | What is the difference between "instantly" and "instantaneously"? | 'Instantly' is relative to a preceding action, similar to 'immediately'. If something happens instantly, it happens right after the preceding action. E.g. 'I clapped my hands, and the lights instantly dimmed.' The actual act of dimming from brightness A to brightness B may take several seconds, but the word 'instantly' indicates that they did so immediately after I clapped my hands.
'Instantaneously' is relative to the start of the action itself. If something happens instantaneously, it happens very quickly. E.g. 'I clapped my hands, and the lights instantaneously turned off.' There may be a slight delay before the lights turn off, but the word 'instantaneously' indicates that they did so in an instant, as opposed to, say, slowly getting dimmer until they turn off. | f785d612-0c88-4927-ac8a-846b4c634620 |
ck32xs | Why is some light warm and cozy and other kinds are harsh and cold? | Yellow light (warm light) looks like, and remind us of fire, which is warm and cozy.
Blue light (cold light) is more like ice, which isn't as cozy.
This is why different light bring different sensations | 08fb9343-23fc-43a2-a955-4c5c324121d5 |
ck3572 | The difference between daily, weekly and monthly disposable contact lenses. | The products are the same but the difference is in the service level, and therefore the price.
If you buy "daily lenses" and they rot after two days - you are on your own. So, the product costs a little less per lens.
If you buy "monthly lenses" and they rot after two days, the manufacturer is liable for injuring you and they have to pay out. So, the product costs a little more per lens. In fact, it costs almost as much more as the market will bear.
But, the products themselves, they are the same. By the way this pricing model appears all over the place.
Food: fancy package or crappy package but same food inside. You can pay more to have a luxury product, and how the customer feels is very important (my kids' health is worth buying the best!)
Aircraft engines: Airlines don't buy the engines, they are provided on leases from the manufacturer, with service included. So you can pay one price with the power de-rated to a certain level, or pay a higher price to unlock the power. And if the pilot gives it more than 100% rated power, say in an emergency, the warranty is voided and they get charged. With the higher power version, of course the service is required more frequently, so it costs more. But, the two engines are the same equipment. | dd14d79f-6448-4e2f-8d94-8f847bc18763 |
ck3ahr | Why steel wool burns the way it does - moving slowly like it's just super hot, but not actually producing a fire | The steel wool oxidizes, effectively becoming rust. As steel requires a shitload of energy to vaporize, it pretty much doesn't produce gasses to burn, so the reaction only happens at the surface of the steel, not in the air around it. Iron oxide is far weaker in tension and shear than steel, so the integrity of the burnt wool is significantly reduced. | 18721408-6df9-4609-a299-db274d3cb222 |
ck3tl1 | Why do some plants and fruits grow in certain part of the world but not in others? | Different tolerances to different climates. Some plants need warmth and sunshine all the time and others can do fine up north. | 31dc8461-b8cf-430f-b442-8118d822a9e6 |
ck3u1f | why hasn't there been any attempt to push for an universal language for us to use? | There has been. Esperanto was designed after World War 2 to reduce the possibility of war due to miscommunication. | 9c1ea33f-654b-4a73-92bc-52c9f5b59330 |
ck43eu | Where does the garbage that they clean off of beaches go? | Yes, it just ends up in the dump, unless they bothered sending the recyclables to recycling. Garbage doesn't randomly spread from the dump to other places, it ended up on the beach because people littered there. | 68a70afb-de64-481c-9063-8ff7e9b79859 |
ck4990 | How concerned would a moon base be about an asteroid hitting since the moon doesn’t have an atmosphere? | Not terribly. The Earth is going to be the main catcher of such asteroids. Despite all the pock-marks on that moon, it doesn't actually catch very many of them. It's just the craters on the moon never go away, save when swallowed by a larger crater.
Micrometeorites are a bigger problem (er, rather, a large -er, more critical concern.) You can deal with them by carefully compartmentalizing your base into individual sealable units. That does add to the overall cost and weight, but odds are, you want your moon base to be modular in anycase. | 546e1473-e2c7-4bf5-a7b6-24f5419a790a |
ck4iw1 | Airborne ocean dwellers | Escaping predators, showing off for mating purposes, shedding parasites can all be reasons why they leap into the air it is then down to the species and circumstances as to what is the main driver. | 89ced4d0-d04c-49bb-a576-5f63d9e9d59f |
ck4k1v | How does a ballbot (a robot that balances and navigates on a single ball) stay balanced? They look like they could easily tip over. | Have you ever tried balancing a long pole or stick on its end with your hands? You have to move your hands towards the direction the stick is falling to keep it upright, and with a little practice your can do so pretty reliably, even while you walk around.
Now imagine if we replace your hand with a motorized ball, and your eyes with accelerometers that can very precisely measure the angle of the stick. We can then program a computer to do exactly what you were doing with your hand, but calculate and correct for the motion of the stick tens or even hundreds of times per second.
That is basically what that robot is doing - constantly determining which direction it's starting to fall and rolling in that direction to counter the fall. | b71f19b4-079d-48d9-9d67-b938329241f4 |
ck4ozq | What is the physiological process of emotional tears? | Tears are all produced by the lacrimal (lachrymal) gland, but psychic tears (sad tears) also coincide with other bodily responses, due to their production being driven from the hypothalamus in the limbic part of the brain. - _URL_0_ | 9bd0ce13-c9e9-4358-b609-817e84b99c1c |
ck58ym | Why is that usually the richer people get, the more conservative they become politically? | Once you have something to lose you May begin to feel threatened by the “takers”...or something like that. | e137cf8c-d85c-4a66-894d-3b8badfed4b4 |
ck5dks | Why aren’t all American kids educated equally in America? | In most areas, the school system is supported by local property taxes, so if it's a poor/rural area, the tax base won't be as big. | 292257ac-6800-4563-ae59-5f5e8ca275ee |
ck5e9d | Why do some parts of the body burn/tan more easily than others? | Thin skin can sunburn way faster. Because there is less area /depth to absorb the energy. Thin skin also has less hair to protect it. | bc66c345-0966-429e-8528-8ede349eb7af |
ck5oep | Why do the nails on my ring fingers grow faster than the other nails? | > ELI5: Why do the nails on my ring fingers grow faster than the other nails?
You're weird
Just kidding. Most of it has to do with blood circulation. Some people's fingernails grow at different rates. Some people find that different fingernails on one hand grow at different rates . Some people find that their fingernails on one hand grow at a faster rate than those on the other hand. | 5b3ca98d-5af8-40b3-8548-cf7e7f27d10f |
ck5ofr | - Why is the process of cooling products down so much slower than heating them up? | The speed of heat transfer is proportional to the difference in temperature between two objects, which means how long it takes to heat or cool something is (non-linearly) proportional to how large a temperature difference you can make between the desired temperature and the heat source/sink you're using. (It's also affected by the particular materials you're using, so trying to boil water by exposing it to hot air is a lot slower than by dropping it on an iron skillet that's the same temperature, but in household use you frequently are just heating or cooling air.)
If you're trying to boil water, you're trying to bring it to 100ºC using a flame that's probably around 2000ºC (eg, a natural gas stove). That's a difference of 1900º, which is quite large, so it goes very quickly.
If you're trying to freeze water, you're trying to bring it to 0ºC using a freezer that's probably around -18ºC. That's a difference of only 18º, so it's going to be relatively slow.
If you tried to boil water using air that was only 120º, it would also take a very long time. Similarly, if you trying to freeze water using air that was -150º, it would go much quicker. But, our household appliances don't provide those things, so we get what we get. | a6fc4934-753f-4d54-a716-4177fb5bde8e |
ck6ajk | Cognitive Behavioural Therapy. | It's essentially talk therapy for a current issue you're having where your counselor makes you categorize the issue into thoughts, actions, and emotions and then address how each of the three relate to the other until you've realized where the unhealthy aspect of the problem is and rationalized your way out of it. Its usually for anxiety disorders like ptsd, ocd, and gad where you fixate on things until you've developed negative repetitive behaviors or thoughts. | 07bc1f28-195d-46f5-ad15-32529918e51b |
ck6lon | I understand that caffeine works binding to the same receptors that our natural sleep inducing chemical binds to, thus blocking them and making us feel less sleepy. How then, can you overdose on caffeine? It shouldn't quicken you up more than it should stop you slowing down or what? | Caffeine does a lot more than just block sleep hormone receptors. It is also a stimulant which works by forcing a fight or flight response from your body. This is why caffeine not only prevents you from getting tired but actively perks you up. The fight or flight responses are what can cause the adverse health effects. By consuming too much caffeine you force your body to redline and hold it there. This causes stress on your brain, hallucinations confusion uncontrolled muscle movement and convulsions, and your heart, irregular heartbeat chest pain and trouble breathing. | 2b6e79f9-f72f-4b3f-a53a-b573375f962e |
ck6o16 | As breasts are designed to feed babies, why do women have two instead of just one? | Average litter size rounded up to the nearest even number because symmetry is easier to code for.
Mammals that have more babies in a litter have more nips | b230a1df-2f7d-4f18-bd3f-a0d50eb25ec6 |
ck71qv | Why can American workers lose their pensions when employers go bankrupt? | Pensions and 401ks are different.
Pensions are paid by your employer. Every payday you make $2000 and your employer kicks in an extra $25 and when you retire you can draw off that fund that's been building since you started working there. And typically there are rules that say when you retire your pension will be at $X amount no matter what.
& #x200B;
401ks are paid by you. So that $2000 you make is now $1975 because its you putting up the $25 to save an invest. But if you quit the job you keep all the 401k money and can put into a new account at your next job. Also sometimes employers do match up to a certain amount in 401ks.
& #x200B;
You're right that Pensions aren't supposed to run out of money but sometimes they do. Maybe the company wasn't paying into them like they should have been. 401ks are risky because since they're typically invested in the stock market there's a risk that a market crash could wipe out the funds.
& #x200B;
When you file for bankruptcy you're telling the world that you don't have the money to pay back everything you owe and in the Mine's case that includes its employees. Now its up to a court to look at what the mine does have and figure out who gets paid, what. That can mean that people do lose money in the end. | 911fb316-aa2f-409d-ab81-aca6f11f19a0 |
ck72rp | Why does faces start to morph and distort in weird ways when you stare at them for a long time? | The main theory is called disassociation fue to lack of stimuli.
To put it simply, your brain is designed to take in the world around you and process it. When nothing is happening your brain basically gets bored and starts acting up. The reason faces get so weird is because of the amount of information in a face, the brain is trained to care alot about faces so when things start to shift due to "brain boredom" a different part of your concious brain freaks out because it knows this shouldn't be happening. | 622509eb-98e2-4255-9e6a-58917b981fb0 |
ck7dlr | Why does spinning around make you dizzy, furthermore why does being dizzy make the floor feel like its moving around? | When you swirl a glass of water, then stop suddenly, the water inside keeps swirling. There's a similar sort of thing inside each of your ears. As you spin, you're swirling the water inside those structures. When you stop, the water keeps swirling, so your brain thinks that you're still spinning.
In response to that spinning, the brain 'modifies' its movements. Eg, it tries to maintain balance and posture and eye direction to counteract the spin. Which is what 'dizziness' is, more or less.
You can replicate this yourself with a spinning chair and a friend. Sit them down, spin the chair, then stop and look at their eyes. You'll see their eyes 'twitching', or shifting back and forth, left and right, very quickly. This is called nystagmus. The brain thinks it's spinning, so moves the eyes the opposite way to keep vision 'locked', but eventually the eyes go too far and 'snap' back.
[Example here](_URL_0_). | 10b44bc5-d155-4dd0-823a-6445cdb00619 |
ck7r86 | How are plant based meats and burgers made? | I did a course on plant based meats in Berkeley. It was an engineering course so I’ll focus on some technical details.
So the main idea for plant-based meat (PBM) is to find a source of protein that has similar nutritional value as meat, and optimally the same taste, texture, colour and smell.
A popular material for PBM is soy protein. This is because soy protein has very similar amino acids proportions to meat, so it can function as a complete protein and you won’t need amino acid supplements. Another option is a blend of wheat, peas and another plant I forgot. This also produces amino acid proportions similar to meat.
For taste and smell, there are flavouring compounds in he industry. Givaudan gave us some fake “chicken” and “beef” samples to try out, and they are remarkably similar in smell. Not so much in taste. Impossible foods uses leghaemoglobin, a protein found in legumes, to mimic the haemoglobin in blood. This makes their PBM taste “bloody”, which is actually pretty good even though it sounds gross.
For texture, there are many tricks used to mimic the muscle fibres in meat. Quorn uses a “flowing stream” to make their fungi grow Long in one direction. The fungi is naturally chewy, so it is a pretty good analogue for meat. There are other methods like a cooking device with 2 cylinders. The PBM is placed between the 2 cylinders and the outer cylinder is spun while cooking. This applies “shear force” which stretches the material and makes the plant fibres aligned in the rotating direction.
For colour, it’s pretty simple. There are many colouring additives, both natural and artificial, that turn brown when cooked. There are also other tricks like adding searing/grill marks to PBM patties so when they’re cooked they look more similar to meat.
For the course “finals” I made fake chicken nuggets. It tasted and smelled great but was really dry since PBMs don’t hold water or oils well. You need to mix solid fats like palm oil into the PBM, but those are generally unhealthy (and palm oil itself is unpopular for ecological reasons). This is probably the largest limitation for engineering PBMs. | b12e70fa-1f01-4e20-a157-1d3a169aa923 |
ck8aey | What is the difference between algebra and calculus? | Algebra deals with numbers, and formulas / equations / relationships between numbers. Calculus deals with functions, and relationships / transformations between functions.
Basically, algebra is "basic math"; you have numbers and you have rules about what it means to add, subtract, multiply, etc. You establish equations and functions (rules that numbers must follow).
The rest of the math builds on top of this, by taking OTHER THINGS and establishing rules and relationships as if these things were numbers. Things like sets of numbers, vectors, functions, "surfaces", "fields", etc., you can define rules about how to add, subtract, and otherwise "interact" with them or the interaction between them. It's useful; for example geometry is about the interaction and properties of shapes and surfaces, and it's useful to have rigid logical / mathematical rules about how they interact. Because a lot of the real world objects are geometrical, and having the geometry rules helps with understanding these real world objects.
So calculus takes functions (relationships between variables) and establishes some rules about them and how they can interact. | 554bd8ce-9039-4081-ad65-52d1b387a3de |
ck8cze | Why do muscles stiffen and lose flexibility? And why does stretching sometimes feel good and sometimes hurt? | Lots and lots of reasons. But ELI5. Muscles get stiff because they get used to being short and all the fibres get tighter and closer together. It can also be because of literal knots in the muscle. Imagine you cut a piece of string in half, to make it whole you have to tie a knot in it. The string is shorter but it’s whole. These are knots and there can be thousands. Thanks to healing and massage those cuts can be healed to normal.
Pain when stretching is normally due to excessive tearing. It’s your body screaming at you to stop. It feels good because of other reasons that I’m not clear on. | 0d61e5b6-d2b8-4e8f-9468-c303ddda5bca |
ck8f6t | What is plaque next to teeth, how is it created? | Plaque is a thin layer of bacteria eating the sugars in your mouth.
It is linked to diet generally. More sugar = more plaque.
I think mouthwash just kills the bacteria. I don't think it washes away plaque. Maybe it does idk.
If you brush/floss often enough and don't eat too much sugar, you'll be fine. If not, that plaque hardens and turns into tartar, which is the leading cause of tooth decay and other dental issues.
Doubt humans are the only ones who get it, but who knows.
I'm sure someone can clarify any details I missed because obviously I kept it pretty simple, and I have a shallow understanding of it.
Edit: animals definitely get plaque, may be composed of different bacteria though. | 4d84b392-8892-493b-b037-7db57ea18fb1 |
ck8i2v | If somebody spits at a crime scene before it takes place and they swab it by accident, could they be charged with DNA evidence? | It possible they would be identified & questioned but if they had reasonable explanation of how spit came to be at the scene & there was no other evidence connecting the spitter to the crime then it highly unlikely they would be considered a suspect let alone charged because the spit alone would never be enough to convict beyond reasonable doubt | edff05e2-1b11-4c20-a2a4-d8365b48f4cd |
ck8rld | If cold air condenses, how can it be true that the lower the pressure gets the colder it is? | Imagine your body has the same properties as air and I placed you into a box that you fit into perfectly. I cool you down, you condense (take up less space) and as such, your body stops touching the wall of the box and you have more room to wiggle.
Now say I heat you up and you expand, you're going to start pressing up against the sides of the box as you take up more space. That pressing up against the wall as the temperature increases is where the increase in pressure comes from. | cf30c329-ec8a-4c29-91ca-681a91b4fa10 |
ck8y1x | why does US employment law allow such incredible insecurity? | It's actually worse than you think.
The two week notice is a common requirement for the *employee* to provide the *employer*. IE, if I am an accountant at a company and I want to gracefully quit my job to take employment somewhere else, I should provide a two week notice to my boss.
But in most, if not all, states, the *employer* has absolutely no legal obligation to give an employee a notification prior to terminating them, except for cases where it's a mass lay-off due to something like a department or factory being closed down. | 06435527-48ae-4f6f-99c4-7df810e6337b |
ck97fu | How does our body REALLY react when we starve ourselves or consume way too few calories a day for a period of time and how come it essentially leads to weight gain most of the time? | Your metabolism will adjust to however many calories you feed it. Up to a certain point. Extreme starvation will put the body into starvation mode or a low metabolic state. Once you've reached this mode and you start eating normally again it takes time for your body's metabolism to adjust. | d158351b-0a70-4c11-94b4-f06d6d4d5d5a |
ck99u2 | Explaining a Sonic Boom | Its important to remember than a sonic boom is not an "explosion" or event that happens at the moment you break the sound barrier. This seems to be a common misunderstanding. As an aircraft travels through the air above the speed of sound, it creates a very high pressure shock wave that trails behind it in a cone shape, like the wake on a ship. This "cone" is dragged along as it flies. At some distance behind the aircraft, this cone shaped shock wave will touch the ground, just like the wake on a ship eventually reaches the shoreline. The people on the ground at this spot will hear a "boom" as the wave passes over them. That is a sonic boom. As the wave continues to pass over the ground, anyone it passes will hear the sonic boom. If the plane flew over the entire United States at supersonic speeds, then everyone underneath the aircraft across the entire US would hear the boom as the wave passes their location.
It's not a singular moment that happens one time. It's a constant event signaled by the movement of the shock wave being dragged along the ground, over the listeners. | b0d78a4e-9272-437a-84ca-4262917a4164 |
ck9c0p | Can you get diabetes if you eat sugar daily but always burn it through sports and endurance exercising? | Yes and no.
Yes because anyone can get diabetes. There are multiple types. Type 1, also known as Juvenile Diabetes because it normally develops in children, is when your immune system attacks the insulin producing cells in the pancreas. Type 1 diabetics will need to inject insulin for the rest of their life.
Type 2 diabetes is when your body becomes resistant to the insulin your body still produces. Type 2 diabetes is normally associated with obesity and sedentary lifestyles, but it can affect nearly anyone.
There are other types, gestational diabetes, LADA, etc., those are the two big ones.
As an anecdote, I was diagnosed with Type 1 shortly after my 26th birthday. I was in the military, and in the best shape of my life. When I went through the diabetic education classes, I was the only Type 1 in attendance. The others were Type 2. Some of those guys were fitter than I was and they still developed an insulin resistance.
So to answer your question in a roundabout way: yes you can get diabetes if you eat sugar daily. You can also get diabetes if you only ate lettuce and celery. | d2569e54-d4aa-40af-9874-5fa30c4f3e15 |
ck9cjc | Is the seasoning or the noodles unhealthy in Instant Ramen? | It's both. The noodles are deep-fried prior to being packaged which makes them high in calories and saturated fat. The season packets use a ton of a salt because it's an easy way to enhance the flavor for cheap. Both are bad independently, so together they are worse.
Don't believe the msg hype, unless you have a particular sensitivity to it, it's perfect fine. Here is one article, but there are plenty of science-backed research and studies into this: _URL_0_ | 24386dc6-342d-42c4-a2a1-b1963b8a9785 |
ck9elh | how come the Alphabet and Cyrillic share so many letters that are either identical or very similar looking, and are sometimes pronounced the same/similar and sometimes not? | The *Latin* alphabet and the *Cyrillic* alphabet are both based very heavily on the *Greek* alphabet.
Which is why "a" (alpha) is the same in all three, and why "gamma" is a г or "rho" (Р) are the same in Cyrillic and Greek.
Historically, Slavs adopted a form of Greek Orthodoxy (one major branch of Christianity), but the Greek alphabet wasn't enough to express all of the sounds in the Slavic language so they had to create new ones at times, which is roughly how the Cyrillic alphabet came to be. | f617d548-1b28-49f9-a0f0-9e4186dcc6ba |
ck9fpk | Why don’t muscles show up on X-Rays, but do on MRIs? | X-rays are effected by dense substances like bone so they are clearly defined on X-rays. MRI or Magnetic Resonance Imagers work by vibrating molecules under a powerful magnetic force show entirely different views of the body - _URL_0_ | 04d773fc-bcd4-4077-aba1-d0e149522a2b |
ck9hd8 | Why does poured liquid drip down the side of a pitcher if not poured at a sufficient angle? | Water really likes to stick to things. When you pour at an angle, the force of gravity is more than the sticking force, so it just falls. But when you tip it just a little, the water will pour over and cling to the surface, and hold on as long as it can. | 91a50f15-fda7-481c-8bb1-be67ba5195e9 |
ck9hf2 | Does weight lifting damage your spine? | Not really... Unless you're using improper form (thus putting extra stress on your spine instead of your muscles and joints), lifting too much for your ability level, or are pushing your body to the extreme. | da924a6a-3061-4e96-be5d-4decd61de230 |
ck9wfd | Why are USB drives default to FAT32 and not NTFS? | Supportability
NTFS is only semi-supported in operating systems other than Windows. Linux and BSD have a free and open-source NTFS driver, called NTFS-3G, with both read and write functionality. macOS comes with read-only support for NTFS; its disabled-by-default write support for NTFS is unstable. | 3594a2b6-dc02-4dea-b6aa-d20a3ef5c374 |
cka2fy | What is the difference in viewing experience in a theater between 35mm film and digital | It's a completely different process. Each has unique artifacts that the other simply can't reproduce. It's also a function of the cinematographer, who may or may not choose to use the media's artifacts for artistic reasons.
35mm film can exist with several different aspect ratios, through the use of special projection lenses, but most digital projector owners don't want to have special glass for movies in ultra-widescreen formats, so they might choose to cut the edges off.
Depending on the camera, each 35mm film frame is exposed for about 1/30^th of a second. This means 24/30^ths of the time the frame is recording and 6/30^ths of each second is used moving the film forward a frame. Digital cameras can come much closer to 1/24^th of a second exposure for each frame, which can minimize blur edge separation in fast-moving objects. This requires very careful lighting control, and unless it's important the cinematographer is likely to use variable exposure time to shoot with the available light, which increases blur edge separation.
Most digital theater projectors are 2K (2048x1080), just a little better than 1080P HDTV (1920x1080). Extra-nice digital theaters are 4K (4096x2160). Basic 35mm film (24mm wide image) is about 3500x1890, 70mm Super PanaVision is about 6900x3000, and 70mm IMAX is 9300x6500. If you look at best-digital vs worst-film, it's about the same, but otherwise film is just a lot more pixels.
Film can project more colors over a wider range than digital projectors. Particularly in dark scenes, which for instance explains a lot about why some fans with their flat panel TVs set for "normal TV" hated recent Game of Thrones scenes while others with their neighbors with their TVs set for "cinema mode" lived it. This should be less of an issue in a professionally run theater, which should calibrate carefully for every movie, but it's another variable in the equation.
Tarantino is another variable. He's a film affectionato, having said many times that he'd retire if he couldn't shoot on film and have viewers see projected film. He's the sort of director most likely to put a cinematographer in a situation where the unique properties of film are required to get the shot. | 549b41d2-6205-4116-beb6-2befd53945de |
cka9dc | How are schools of fish so organized with their movements if they don’t make noise and can’t communicate? | Fish have sensory organs along the sides of their body, called the lateral line, that can detect changes in water pressure. When one fish turns, it creates vibrations in the water other fish react to, maintaining their schooling pattern. | 8db3e60c-a656-4b6a-9a6d-a9677e6fb35a |
ckaww5 | Why does macaroni and cheese lose so much flavor when refrigerated then reheated? | When you re-heat things in a microwave, water molecules are what absorb the microwaves and receive the energy. With things like cheese, that makes the water kind of separate out and makes the cheese more 'soggy and stringy' instead of 'foamy'. Texture changes taste.
If you re-heat your Mac and cheese in an oven instead of a microwave, it will be much better. | d44a08df-8c59-4c67-8414-82e91190290f |
ckaykb | why does eating unhealthy foods make your body crave unhealthy foods? | One simple mechanism is due to blood sugar levels.
Most of your body can burn sugar for fuel, or other stuff. Your brain can only use sugar (with a few exceptions).
To keep your muscles and whatnot from using up all the blood sugar and killing you, your body uses insulin as a signal for when it's ok for the rest of your body to burn sugar. If your blood sugar is low, the insulin level drops, so that the sugar in your blood is reserved for the brain.
Carby, starchy foods cause a big rise in blood sugar. This causes a big rise in insulin. This causes your body to burn lots of sugar... which leads to your blood sugar getting low. Low blood sugar causes an especially ravenous type of hunger called glucoprivic hunger, which makes sense because without modern medicine, if your brain runs out of sugar, you're going to fall unconscious and then die. So your body responds by driving you to IMMEDIATELY go eat. And if what you go eat is mostly carbs, we start over again: high blood sugar, insulin, low blood sugar, ravenous eating.
When carbs are a smaller percentage of your diet, your insulin levels don't get so high and your body doesn't burn sugar so fast (because it's got plenty of other stuff besides sugar to burn), and so your blood sugar never gets crazy low (driving you into Single-Minded Food Acquisition Mode). | bb5784c3-7cd2-421a-8720-5bb5ee14c356 |
ckb52a | Why are muscles sore the first time you work out after a long period of inactivity but not the second time? | We do not have a very strong understanding of [Delayed Onset Muscle Soreness (DOMS)](_URL_0_). The leading theory is the pain is the result of the small tears your muscles which occur during the part of movement where your muscle is contracting but lengthening (eccentric phase). Muscles can only contract (shorten) but there are parts of movements where your muscle is contracting however a load or another muscle is exerting a greater force and lengthening the muscle.
The reason you tend to experience DOMS less when you routinely exercise is what is called the "Repeated-Bout Effect". This is the combination of your muscles repairing the previous tears and being better adapted for the activity. Your body is also better prepared to deal with new microtears in your muscles.
As far as why is day 2 DOMS worse than day 1 DOMS - we do not know. It could be just the constant stimulation of the cells that tell our brain we should feel pain (nociceptors) and how our brain processes it. It could be the result of the repair process for the tears and a protective adaptation to try to discourage more exercise until it has better healed. Or both, or something else. | afa315c7-6720-4a91-a26e-8b1bc3f66702 |
ckb9ac | how those catfish bots on dating sites work, how are they coded and implemented | Bot bot = new Bot(’Tiffany’);
If(guy) {
bot.swipeLeft();
bot.say(’hi there stranger wan som fuq’);
If(guy.answer === ’yes plz’) {
bot.say(’plis snd credit card detailz’);
}
} else {
bot.swipeRight();
} | d7e9c22f-72c9-4ea3-b056-9c52edd5de09 |
ckbfku | Why are darker surfaces more reflective (like black cars vs. white cars), when a typical mirror seems very light and bright? | Actually the reflection comes from the gloss layer, outside the colored layer.
But when the colored layer is light (white, yellow, etc.) its brightness makes it hard to see that reflection. When the colored layer is very dark, it doesn't interfere with your seeing the reflection. | dd4f4292-e725-4bff-8ead-bd23bdcb2dfc |
ckbhky | How do TV channels/shows generate revenue by views and ratings? | Good show = more viewers = more companies wanting to pay for advertising spots during commercial breaks = DOLLAH DOLLAH | d6882dff-0d6b-47ff-be2b-bd0388e81536 |
ckbs96 | How or why does the pole disappear in those awesome gopro videos? All I ever see is the person holding something or a fixed point on the body, but nothing is visible. | One of the comments in your link mentions the insta360 camera rather than a gopro. It edits out it's own handle from the video. | 46975f11-6b40-48ed-a606-805e2802d99f |
ckbwsd | Why does the earth-facing side of the moon have more craters than the 'backside'? | According to [NASA](_URL_0_ ) this is completely wrong. The far side has more craters, because the near side has thinner areas of crust and more extensive volcanism where lava flows "erased" some of the carters. | 0980a86f-d3c3-459b-861d-cf85b63f21d9 |
ckc0dh | Why are online password managers so much safer than writing passwords in a book that’s kept in a safe place? | This is an example password that my password manager makes: xmJWI#Nrjmx7oXu%hLmc70mU$\*zi9U
Every place I have a password for has a password like that (or as long and complicated as they will allow) that is unique.
I change them all frequently.
Are you /really/ going to make, update, remember and consistently use really good passwords in your book? | 996bcce3-ea66-475a-9600-330c4a942c35 |
ckc9ug | Why are all negative temperatures hotter than the Planck temperature? | So here's the thing:
Temperature is caused by how much energy atoms have. Atoms like to move, but since they're so small you generally don't see it. The more they move the hotter they are.
If they reach a certain temperature they break atomic bonda and change phase. There are many phases of matter but the four ones you see the most are solids, liquids, gasses (you can see chlorine as a green gas) and plasma (stuff that lightning is made out of).
The higher the temperature, the closer to plasma the atoms are. The lower the temperature the closer to solids they are (generally).
So at colder temperatures, atoms vibrate less, which means it's possible for them to not vibrate at all. The tempreature at which all atoms stop vibrating is called Absolute Zero. On the Celsius scale this is about -273 dregrees and something like -459 degrees Farenheit.
There are, however many ways to measure temperature. One such way is Kelvin. An average day is around 300 degrees Kelvin (or 300K).
So what is 0K? 0K is Absolute Zero.
Now if you fail to comprehend how cold Absolute Zero is, here's an example.
It's literally colder than the average temperature of the Universe. It is literally impossible to get colder.
Therefore if there is a colder temperature it would break the laws of physics and nothing would really matter.
Am I interpreting your question wrong? | 575ff240-d976-4ba9-a564-36c7b82d4731 |
ckceyk | Why do 12 hours at home fly by for me, yet 12 hours at work seems like an eternity? | I’d assume its because your mind at home is occupied by leisurely activities, whereas at work you’re occupied with things that are generally not interesting to do. Therefore, it seems as if you’re spending a greater deal of time doing something at work | fa32d4dd-f0dc-456e-8d6d-15e00c3455d1 |
ckck92 | What are tears made from? | They are mostly water and salt, both pulled from the blood supply by the tear glands that exude them. You will find that most things in the body use blood to move their supplies around the body. | eb5a3474-4e7a-43db-9211-c143288b500f |
ckcnnv | Why do airplane passengers need to turn off cellphones or electronic devices while a plane takes off/lands? | Its nonsense. Its based on old avionics devices that could have radio interference , afyer that it was because "holy shiit you never know". but today's technology has changed the game. Did years ago. | 09e3951d-3f08-49cc-848f-093b7f244850 |
ckd2tt | how are molecules and atoms studied? | A lot of discoveries are made using very very clever experiments. Take the nuclei of the atom, how do we know it is there if we can never see it? we can take a small sample, and place it in the centre of a ring of detectors and fire particles at it. If the atom is a blob of protons/electrons (plum pudding model) then we expect there to be a hole the size of the sample on the detector. But when we ran the experiment, not only did we have particles hit the otherside as if nothing happened but we also got reflections as if they hit something hard and bounced off, and also refractions like it was pushed by something off its trajectory, which would make sense in a nuclei + orbiting electrons.
& #x200B;
Later with things like molecular structure, we can use other things we know that are true about the atoms. If we know Nuclei are charged and have spin, we can see how their magnetic fields interact with their neighbours in an NMR experiment. From the way their magnetic fields interact, we can say this atom must be next to that atom.
& #x200B;
There are a plethora of tests we can do by taking theoretical calculations and matching them to real world results. | 45a0e7da-25c0-4a18-b7ae-94c3cf3434eb |
ckd7dl | why are my pasta leftovers oily when reheated | The oils were originally mixed with the sauce. When you let the pasta settle, the oils and melted fat will travel to the top surface of the dish because they are less dense, much like letting a bottle of salad dressing settle until the oils form their own layer on the top.
When reheated, the oils and melted fat remain as its own layer on top of the pasta, making it feel oilier than when the oil was within the sauce. | a6a1f486-e81e-443c-8e07-4163985c3a81 |
ckddwy | Why do automatic payroll systems round up or down to the nearest half hour or quarter hour? | Saves the company money by paying people 8 hours when they actually clocked in at 7:57 and out at 4:03.
It's only 6 minutes a day, but that's over 26 *hours* a year. Per employee.
Also removes the incentive for employees to intentionally do this to game the clock. | b3f2edbd-0830-47ee-afab-cc20e2e86823 |
ckdg2d | how does medication half-life work? | As the other poster mentioned, you can get down to a point where either the last molecule decomposes, is removed, or is no longer detectable. In practice, the rule of thumb is that the drug has been functionally removed from the body after about 5 half-lives. | f1074cff-a2e1-4f1f-9afa-6dbb3c4b8c17 |
ckea12 | How are different forms of medication "activated" by the body when taken simultaneously? | Med student here. Any medication you take by mouth is going to go through a "first pass" effect. It won't get fully absorbed, it gets broken down by your liver, etc so it never actually reaches general circulation in your blood.
Many oral medications are actually 'activated' by stomach acid, the low pH makes it easier for the drug to be absorbed by the gut and get to your blood.
As for whether or not two drugs taken at the same time will combine to form a different chemical structure: not really. I'm sure that may happen on a small scale, but I don't think it will have a big effect. | e602c696-a66d-41f4-8921-f74b232630ff |
ckeahe | What exactly is a pyramid scheme? | A pyramid scheme is a money-making venture built on lies.
The guy who makes it recruits a few people for a fee, who each recruit a few more. The new recruits are the source of income for the whole company.
It's called a pyramid scheme because, like a pyramid, it has a large base leading up to a single point.
And they are illegal because no matter how strong the pyramid seems, you eventually run out of new people to recruit.
Without new recruits, the people on the bottom have spent money, but not made money, and are left in debt. | 77e9bb56-2dea-432e-9f83-b4f33d65d098 |
ckebnv | What does it mean that a human shares approximately 50% of their DNA with the "parent" even though all humans share over 99.9% of their DNA with each other? | We as humans all share the same genes. For exampe each of us has a gene for hair, eye color, height (just for simplicity lets imagine they are all a result of one gene)
Each of those genes though has different varieties. These varieties are called alleles and these are the reason why although we all have hair...each of us can have hair of different colors and types.
When you inherit DNA from your parents, you are inheriting each of their alleles. You have the same genes as your parents, but 50% of those genes are mom variety and 50% is dad variety.
Contrast this to a plant which has different genes all together. We might share similar genes for things like mitochondria, but plants have a genes for things like photosynthesis that we dont. | da05a9bb-6b72-4a59-b135-332c556de75c |
ckehsw | If you throw a cantaloupe in the air in a fast moving car, why does it go straight up and down and not backwards? | Because everything in the car when you were holding it was moving (let's say) 60 miles per hour. When you throw it up, it's still moving forward at 60 miles per hour, the same as everything else in the car. | d392ab43-bb1e-4044-803d-fdc278aa3a3a |
ckerax | Why/how does a song make you tear up (usually wistfully) even if/when it's the first time you hear it? | Music causes activity in the amygdala and hippocampus, two parts of the brain intimately associated with emotional processing.
Some people say we aren't actually feeling "emotion" in the traditional sense, but rather building up tension and experiencing relief, either good or bad depending on how your brain expected the music to proceed. | d7945a4a-a77d-42d4-8085-f83995545a84 |
ckev32 | How does the deja-vu works ? | Like most things with our brains, we don't really know. But we have some ideas.
One idea is that it's a almost kinda like a siezure, a bit of uncontrolled electrical activity (please note that having deja vu doesn't mean you have epilepsy or something similar, it's more like when you're falling asleep and then feel like your falling and you "jump" a bit). It might be in the parts of your brain that process time, or memory causing you to perceive the present as the past.
Another idea is based on signal processing. Sensory info goes to multiple spots in your brain and if a signal gets delayed a bit somehow, your brain may mistake the delayed signal as a new experience. | ae643439-b889-40ff-b034-fcf9f39bdfa3 |
ckev6w | The Fed cut their rate by 25 points, what does this mean for the average American & their mortgage & credit card rates? | For the average american it means absolutely nothing. Zero. Nothing at all for average people.
First of all the change was very small, and second, this is more macro economic (think "big overall economy stuff", not your job or buying a sandwich). It will likely have just about zero effect on each individual person, but overall the goal is that it tries to effect the economy just a tiny bit in the grand scheme of things. Its just a tiny nudge to the overall economy in one way | 3c3bf51c-5adc-42e2-9e7b-52c5d47bce6b |
ckewxn | If the light switch is on but the bulb is dead, is power still being used? | It can’t be a full circuit if the bulb is broken, so no. It’s as if a switch is off and the circuit just doesn’t complete. | 186c87ee-171e-4f93-9d64-2f6d74dcd165 |
ckey13 | Why is it okay to eat mayonnaise - which contains raw eggs - but not cookie dough, which also contains raw eggs? | Because mayonnaise has been pasteurized to remove bacteria from the raw eggs. Your cookie dough has not. | 56cdff87-d688-4b2a-91e9-230d64784f1c |
ckez02 | When there is a security breach that can result in identity theft, why can't the government simply issue new SINs and close down the existing ones? | Because that would be a major logistical nightmare. SSNs are unique and so ingrained into the USA that being able to change it would create it's own problems that there is no process in place to handle. Not to mention that by changing a ssn could itself lead to fraud and identity theft as there is a limited number of numbers and reusing it would cause more problems. | 6406b372-a740-404b-8993-b28fbdba97c7 |
ckfb90 | why fleas don’t infest hairy parts of humans. | They do. Humans can get and carry fleas just like any other fuzzy mammal. That's how the Bubonic Plague spread, fleas and rats. | d756035d-a9a1-45d7-8fc6-b1bdff9d4f76 |
ckfcyr | How do All-Female lion prides form? Can male cubs grow to be leader? | There are lone males who are wandering around who challenge for leadership of prides and a vacant space will rapidly be taken by one of these. | 84052ad1-233e-4779-a429-dbebe28dec95 |
ckfi27 | how do scientists determine the age of cave paintings? | Lots of ways.
If the pigments were made from something that was once alive, then the pigments can be dated using radiocarbon dating. A certain form of carbon decays at a set rate, and since the living thing only adds carbon to itself when its alive, you can track the ratio of radioactive carbon to regular carbon and estimate a date. This has some drawbacks, especially if the area was subject to burning, and it can only tell you how old (approximately) the thing used to make the pigment was when it died. That's still pretty useful though, at least within a specific time range before it's too hard to figure out the age.
Another way works if you're in a cave with layered paintings. If you can date one or two layers, but not some other ones you can get minimal or maximal ages for the layers above and below the dated ones.
You can also date the rock itself, and the mineral deposits that build up for many many years. This is done using a variety of methods, including uranium series dating.
Most of all, you can look at the layers laid down over time, both on the ground of the cave and the walls of the cave itself. By comparing known processes and events such as floods, mineral deposits, and more, you can set a timeline for the surface of the cave. This process of studying the strata (stratiography) is just like what archaeologists do when digging in the ground; it's just on the wall of a cave instead of in the ground. | 55266dc7-c41b-4639-90d1-8480b71dc590 |
ckfiut | How does the heart regulate its beat so perfectly? What is happening to this system when we have palpitations? | Your heart has pacemaker cells that can actually regulate the heartbeat themselves without input from your brain. They start the electrical signal within your heart to beat, and they do so with awesome precision and rhythm. The signal then travels down your heart through a pathway made for those electrical signals, and you get a heartbeat.
Your nervous system also supplies nerves to the heart that can increase or decrease the rate that those pacemaker cells fire at (thus changing the heart rate). But the pacemaker cells don't need the nervous system to work. The heart is pretty nifty that way.
'Palpitations' is really nonspecific and can mean anything from a fast heartrate to skipped beats to a heart rate that is just completely irregular. But, overall, these can occur when any of the above steps have issues. There are a lot of different causes. | 8fd817bc-eb82-46df-ac0d-9172b4abea82 |
ckfqpj | Does using a fan make dry eyes worse? + tips on healing dry eyes please | I am living with severe dry eyes and I can’t have a fan running in the room without it making my eyes worse. Can you get a window air conditioning unit? I’m not sure there is a “cure” for dry eyes. Try using a drop with castor oil in it, that may help. | 10201076-fa6b-4fdc-ad49-4013df14a84e |
ckfrwx | Do we all see the same color or my red can be your blue? | Most likely that we all see colors the same since we all have similar structures in our eyes and brains to receive and process visual information. However, there's no definitive way to prove it. | 4215270f-f432-4016-955a-6d6250208e94 |
ckfv7s | what does that often blue tape that athletes put all over themselves do and how does it work? | It's called Kinesio tape.
Its supposed to support muscles and potentially improve performance and help prevent injuries and help in injury recover. I'll stop explaining what its supposed to do or how any more because of something else associated with the tape:
There's little evidence it works at all, and plenty of experts think its complete pseudo-science nonsense and at best simply a placebo. This hasn't really stopped anyone from using it though.
I've personally used it and had it put on by professionals. I never noticed a difference and even the trainers putting it on me admitted its probably nonsense. | 429133d0-312c-4d51-95af-e5ba93ba81b3 |
ckg0co | If cells die of age, where do new ones come from? | That gets a bit complicated because it depends on the organ.
A lot of organs in your body (skin, intestine, stomach...) have a layer of cells that are capable of dividing indefinitely (well, at least until you, as a person, pass away) to keep the organ healthy. The big problem with these cells is the further along they go, the more susceptible they are to becoming cancerous. The perfect example is your skin. The top layers are dead cells that just continuously slough off. Underneath several layers of this, there exists a layer of basal cells that just keep dividing to keep your skin intact.
Other organs (heart) actually have cells that never divide again once the organ is formed. This is part of why a heart attack can be so dangerous: the cells that die can't ever actually come back, nor can they be replaced by new cardiac muscle cells. They just get replaced by a scar (made of a different type of cell) | 5853c4ca-d4f4-4d49-b532-e7f9c4cd0c00 |
ckgagf | why the future of the planet depends on saving the bees. What makes bees so special in nature? How do we actually save them and why are they dying? | Why are they important? One world: pollination. All crops need to be pollinated to produce. A tomato plant or strawberry plant that goes un-pollinated will never fruit. Most of our food is bee-pollinated. The "how we actually save them" is a tricky question and "why are they dying" is even trickier to answer! Scientists haven't actually conclusively figured out what the deal with colony collapse is (though there are plenty of theories). The best things WE can do on an individual, local basis is perseve/plant as much habitat and food as we can for our local bees and refrain from using pesticides whenever possible. | 17acca72-474f-49aa-bf72-8f86ba93616f |
ckgil4 | Why can people with Alzheimer's easily remember their childhood and young adult life but not recent events? | It could be that long term memories are stored in the frontal lobe of the brain and Alzheimers first targets the hippocampus, which is responsible for memory reconsolidation (the creation of long term memories from short term memories) | c56d5bf6-00f6-4c5c-9d00-b81f62aae70e |