question stringlengths 3 301 | answer stringlengths 9 26.1k | context list |
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why cant we just send money to other countries to pay for their food? | One thing to consider: the only reason gas is so cheap in Venezuela is that the government deliberately pays over 90 percent of the cost to keep prices down and avoid...well, at best rioting and at worst a full scale revolution. | [
"Senders and recipients have the option of paying or receiving payment in their own local currency. This supposedly makes life easier for small producers, which until then were used to sell and buy goods only in their own currencies. They don’t have to fix their prices in US-Dollars or calculate exchange-rates thei... |
li5: financial derivatives | Here is an excellent answer to your question, which was asked a few hours ago: [Here](_URL_0_) | [
"In finance, a derivative is a contract that \"derives\" its value from the performance of an underlying entity. This underlying entity can be an asset, index, or interest rate, and is often simply called the \"underlying\". Derivatives can be used for a number of purposes, including insuring against price movement... |
how is there nothing in space? i get that there isn’t necessarily air like we have in our atmosphere on earth, but how can there be nothing? | Most theories think the universe started out as mostly gaseous, but particles of matter attract each other through the force of gravity (which is something you get for free, as a fundamental property of matter). When matter starts to clump together, voids are left in space - and over a very, very long time, those voids get very large.
There are still gas clouds out in space, but there is a lot of volume of space that contains nothing at all. | [
"One part of space is not by itself and in the absolute sense of the word equal to another part of space, for if it is so for us, it will not be so for the inhabitants of the universe B, and they have precisely as much right to reject our opinion as we have to condemn theirs.brbr\n",
"Atmospherics is a qualitativ... |
how does wii emulation work? | The motion controls are just values fed into the Wii - if you’re rotating the Wii remote slightly upwards, it’s just increasing the value of the y-axis’ rotation, for example.
A lot of Wii games only have basic motion controls, for instance “flick the remote” or “tilt the remote sideways”, without requiring precise controls. In Dolphin, you can set controls for these, like a key for changing the value of one of the remote’s axis values by 90° (thus “turning” your simulated remote) and a key for the “flick” response (which would generally involve a very quick value-change). So, for example, when I was playing Super Mario Galaxy, I set Q and E to mean “turn the remote 90° (counter-)clockwise” and left click to mean “flick the remote”.
If you’re playing something like Skyward Sword, which requires a Wii Motion+ and more precise movement, you can still do this, but it won’t be as good. It’s better to use a Wiimote for that. | [
"Emulation is a technique that allows a computer to execute binary code that was compiled for a different type of computer. Before IBM's acquisition of QuickTransit in 2009, application binary software for IRIX/MIPS and Solaris/SPARC could run via type of emulation called \"dynamic binary translation\" on Linux/Ita... |
how fast do airplanes fly? and why doesn't it seem like we are going that fast? | planes don't got 500-700mph when they takeoff. take off and landing speeds are 150-200mph.
you don't feel speed. you feel acceleration. | [
"BULLET::::- The fastest civilian airplane currently flying: the Cessna Citation X, an American business jet, capable of Mach 0.935 (over 600 mph at cruising altitude). Its rival, the American Gulfstream G650 business jet, can reach Mach 0.925\n",
"The aircraft uses two 2439 KW Allison AE 2100C turboprop engines.... |
How fast/close/times can i use gravity to slingshot out to interstellar space? | It only takes one pass by Jupiter to find yourself with enough speed to escape the solar system—Voyager 2 did it. See [this](_URL_3_) graph; once you're above the blue line you are leaving the solar system unless you do something about it. Interestingly, note that Voyager 2 got a negative assist from Neptune. It would be traveling a couple km/s faster if it had not enocuntered Neptune, but observing Neptune was part of its mission.
Once you reach solar escape velocity you don't get to make another pass of Jupiter. Your best bet would be to make one weak pass of Jupiter to put yourself in a high elliptic orbit around the sun, then come in on your next orbit (dozens of years later, I would point out) and perform the mother of all periapsis kicks just as you're passing.
Busting out the orbital mechanics, the first gravity assist would be able to get you to an orbital energy of essentially zero (note that orbits have negative energy; escape trajectories have positive energy). When you come back around to encounter Jupiter again you'd be traveling at [18.2 km/s](_URL_4_). Jupiter is orbiting at [13 km/s](_URL_1_), so you'd be traveling at 31.2 km/s relative to Jupiter in the best case scenario (you make a near-zero-cost maneuver while high above the sun so that you approach Jupiter head-on). That's a specific energy of [486.7 MJ/kg](_URL_5_).
From there you fall to your periapsis. You probably shouldn't get closer than about 75,000 km from the center of the planet (the Jovian atmosphere is 1 bar at 71,492 km; the distance here is less substantial than my other roundoff. When you get to that altitude you'll be at about [66 km/s](_URL_7_). This is the point where it's best to burn any remaining fuel. I estimated that a Voyager-sized probe may have the capacity for an extra 7 km/s of delta-V if it had been launced from a Saturn V instead of a Titan IIIE, so let's tack that on here. High I*_sp_* engines like VASIMR or electrostatic thrusters aren't feasible here since you need to burn quickly while you're at a low altitude.
When accounting for this extra velocity we have a speed of 73 km/s. That's a specific energy of [975 MJ/kg](_URL_8_). Converting to excess escape velocity gives [44 km/s](_URL_6_). Then you have to convert back into a heliocentric reference frame. Ideally this slingshot has swung you all the way around Jupiter and you get to add its orbital velocity again (this is the premise of a gravity assist), but in order to add it directly you need to make a zero-altitude pass around the center of the planet, which is obviously impossible. I've done too much math for this comment already, so I'll just guess and say that you get an even 6 km/s added back to your velocity so that my answer is a nice round 50 km/s velocity as you leave Jupiter. From there you could possibly try to do similar shenanigans around other planets (including Earth); there's no limit to how many times you can do this in theory, but in practice it gets harder and harder and it's more and more rare to be able to get the phasing right.
Finally, it's worth calculating the solar escape velocity. The probe will slow down as it leaves the influence of the sun. The specific energy as it leaves Jupiter would be about [1.08 GJ/kg](_URL_0_). Converting to excess escape velocity gives [46.5 km/s](_URL_2_). | [
"The gravitational slingshot technique uses the gravity of planets and moons to change the speed and direction of a spacecraft without using fuel. In typical example, a spacecraft is sent to a distant planet on a path that is much faster than what the Hohmann transfer would call for. This would typically mean that ... |
How do animals like horseshoe crabs process information from so many eyes? | I did not know the answer to your question bit started wondering myself as well. I am not sure what tour background is but these two links should provide accesible information:
_URL_1_
This wiki contains a lot of information about the processing of compound eye information in insects
_URL_0_
This piece in the new scientist discusses some work done in Ron Hoy's lab at Cornell about sight in spiders(which have multiple eyes that vary from simple ocelli to compound eyes to some more elaborate structures)
| [
"The horseshoe crab has traditionally been used in investigations into the eye, because it has relatively large ommatidia with large nerve fibres (making them easy to experiment on). It also falls in the stem group of the chelicerates; its eyes are believed to represent the ancestral condition because they have cha... |
Naval history? These unique antique doors are from an inn in Wales, but nobody (including the owner) knows what they are. Are they gun doors? (x-post) | It seems unlikely that they are from a ship at all. Those chains, assuming they're original to the "lids", would be an odd choice for shipboard use due to their weight. Ropes were much more the order of the day. These ropes, in turn, attached to eyebolts, which were usually integral to the metal straps, rather than in the wood of the lid. | [
"The walls of the inn hold numerous historic artifacts. Paintings are prominently displayed of famous vessels from the age of sail and steam, and the Gun Room has a collection of rare firearms. The inn has the largest privately held collection of the works of Antonio Jacobsen, the country's most prolific painter of... |
how big a problem is all the debris in orbit around earth? what can be done about it? | It's not necessarily a humongous threat, but it's definitely big enough to have to be accounted for when you're doing anything up there. Earth is enormous and there is a LOT of space between these thousands of pieces of debris. However, something will eventually hit, which obviously causes a problem.
As /u/fillingtheland stated, there are several projects in the works (via discussion or actually working on) that will be attempts to solve the debris issue. It will be a difficult thing however, since debris travel at a high rate of speed, due to gravity and the lack of any kind of resistance in space. | [
"\"Space debris\" usually refers to the remains of spacecraft that have either fallen to Earth or are still orbiting Earth. Space debris may also consist of natural components such as chunks of rock and ice. The problem of space debris has grown as various space programs have left legacies of launches, explosions, ... |
Why did the US end up so much more economically successful than Brazil? | Brazil's only capital rich land lies to the south, near the border with Uruguay. All other lands are more capital poor because of temperature and challenging geography. The United States is a massive power because it controls the mississippi river system, which is the largest interconnected river system in the world. Rivers are like veins for countries. They make it easier and cheaper to move goods and products around, which makes it more profitable to do so. Not only this, but overlaying the mississippi is the second largest piece of arable farmland on the planet. The combinations of an excess of capital rich lands, a large river network, and an absence of enemies allowed the US to grow into the strongest industrial power. Once it gained access to the pacific ocean, it was able to project power both east and west, making it a global superpower. Brazil has none of these advantages. Brazil is large in physical size, but has little else. Even the lands of the interior that are not jungle require extensive fertilization and clearing to be profitable, and maintenance must be continued regularly to keep them profitable. The US is successful simply because it holds the best lands with the fewest constraints. Brazil isn't because it holds only a small region of capital rich land and faces many constraints.
But geography isn't the end of the road. Argentina by all accounts SHOULD be a great power having the best lands in South America...but it isn't. | [
"The Great Depression possibly had a more dramatic effect on Brazil than on the United States. The collapse of Brazil's valorization (price support) program, a safety net in times of economic crisis, was strongly intertwined with the collapse of the central government, whose base of support resided in the landed ol... |
What was the relationship like between Ptolemaic ancient Egypt and the Carthaginian Empire? | The short answer is that Egypt had better things to worry about than sticking its nose into Western Mediterranean affairs.
For most of the First Punic War (264-241), it was hardly clear that Rome would be victorious. The larger issue was that the Ptolemaic Kingdom had much more immediate threats than Rome. Magos, a brother of Ptolemy II (I believe) had declared himself king in Cyrenaica (around modern-day Benghazi, Libya). While not a major threat to Egypt itself, this was something of a distraction until halfway through PW1. More importantly, Egypt was preoccupied by the threat of Macedon and the Seleucid Empire. In short, between Cyrenaica to the west, Macedon stealing Ptolemaic islands in the Aegean, and the Seleucid threat to the east, there wasn't really a question of Egypt helping Carthage, whether or not they wanted to.
By the Second Punic War (218-201), Rome was clearly dominant, and Carthaginian successes were largely due to the brilliance of Hannibal, the incompetence of Roman leaders, and the alliance between Hannibal and Philip V of Macedon (throughout most of PW2, Rome was also fighting a concurrent war in Greece against the Macedonians). Furthermore, the Ptolemaic navy never really recovered from its defeat at the Battle of Andros in 245 in the Third Syrian War against the Seleucids, and they concentrated on land forces after that. With their focus on Seleucid territories in Asia, Egypt had no chance of projecting its power into the Western Mediterranean. They maintained a strict policy of neutrality.
(This is my first post here, and I hope it's helpful. I'm not a historian, just a lover of history who just finished reading "Roman and Hellenistic Naval Wars" by John D. Grainger. I imagine you'll get more complete answers from bonafide classicists.) | [
"Ptolemy's family ruled Egypt until the Roman conquest of 30 BC. All the male rulers of the dynasty took the name Ptolemy. Ptolemaic queens, some of whom were the sisters of their husbands, were usually called Cleopatra, Arsinoe, or Berenice. The most famous member of the line was the last queen, Cleopatra VII, kno... |
When the weather report says the temperature is X, but it feels like Y because of the humidity, what is the relative humidity they're assuming for Y? | Heat index (and wind chill, in areas where it's relevant) are a measure of how fast the body sheds heat in given conditions.
There are four ways for something to cool off: conduction, convection, radiation, and evaporation. For the most part, we rely on convection and evaporation to cool our bodies.
When we go for a swim in cool water, we're losing heat through conduction: the water absorbs heat directly from our skin.
When it's cool outside, we rely on convection currents (which also involves conduction): our body heats the layer of air in direct contact with our skin, which expands and rises away from our body. It draws in new air, which absorbs more heat from our skin, and so on and so forth.
When the temperature is close to the same as our body temperature, conduction and convection stop working. When the air temp is *higher* than body temp, they work in reverse, heating us up. In these cases, we rely on evaporation--that is, we sweat. The sweat evaporates, taking heat with it.
How fast sweat evaporates depends on the relative humidity: as humidity rises, evaporation slows--and so does the cooling effect.
What makes us feel hot or cold is how fast or slow we gain heat from or lose heat to the environment. When that heat transfer slows to a crawl because of humidity, it feels a lot hotter.
If we're losing heat as slowly as we would at 105°F, that's what it feels like, even if the air temp is only 89°F. | [
"The humidex (short for humidity index) is an index number used by Canadian meteorologists to describe how hot the weather feels to the average person, by combining the effect of heat and humidity. The term humidex was first coined in 1965. The humidex is a nominally dimensionless quantity (though generally recogni... |
What was socialism before Marx? | Well, that doesn't make a lot of sense since while there was socialism pre-Marx, Walter Ulbricht was member of the left.wing of the German Social Democratic party under Luxemburg and Liebknecht, both would classify as rather Marxist Communists of the Council Communist variety.
Don't get me wrong, there is non-Marxian socialism such as Autonomism, Mutualism, and Anarcho-syndicalism but Ulbircht is firmly embedded in the Marxist tradition of socialism.
Perhaps your confusion arises from the different terminology in terms of Socialism and Marxism: Socialism in the broadest sense refers to a society in which the means of production are socialised and is generally seen as a way to Communism, i.e. a society in which property of the means of production ceased to be altogether and thus the state, money and class cease to exist altogether. Now, in a socialist society of whatever variety, semblance of the old order still remains.
The question of Marxian vs. non-Marxian ways of socialism often refers to the role of the state in the period of transition from capitalist to communist society, several prominent brands of Marxist-socialism such Marxist Leninism placing the state in lieu of the community owning the means of production.
While Ulbricht was a council communist, i.e. a form of socialim in which the means of production are controlled by councils, and not a Marxist Leninist, this is not incompatable with Marxist theories. | [
"For Marxists, socialism or, as Marx termed it, the first phase of communist society, can be viewed as a transitional stage characterised by common or state ownership of the means of production under democratic workers' control and management, which Engels argued was beginning to be realised in the Paris Commune of... |
What was the difference between women and men’s labor camps during Nazi Germany? | Quite interested in this, waiting on a response also! | [
"Near the end of the war, women were forced from factories in the German Labour Exchange and sent to training centres. Women were also trained on a smaller scale at the camps of Neuengamme; Auschwitz I, II, and III; Flossenbürg (as well as Dresden-Goehle, Holleischen and Zwodau); Gross Rosen (as well as its satelli... |
Do historians believe the Carthaginians, around the time of Hamilcar and Hannibal, were black/dark skinned or more fair skinned? | They were more likely to be fairer skin. Carthage was founded as a Phoenician colony and the Phoenicians themselves were a Semitic people. The region that they settled (modern Tunisia) was populated by Libyans who bear more resemblance to modern day Berbers (group of people dispersed across much North Africa). In other words they probably had a more stereotypical "Mediterranean" or even "Middle Eastern" appearance than black. It's possible that there were "black" Carthaginians because the cosmopolitan/mercantile nature of the city connected it with peoples across the ancient world, including other parts of Africa. | [
"From the Second Punic War until the 3rd century AD, the bulk of Rome's light cavalry (apart from mounted archers from Syria) was provided by the inhabitants of the Maghrebi provinces of Africa and Mauretania Caesariensis, the Numidae or Mauri (from whom derives the English term \"Moors\"), who were the ancestors o... |
How does the "Stimulated Emission" part of a Laser work? | It has to do with the statistics of exchanging bosons. You may have learned the "Pauli exclusion principle" that no two fermions (spin-1/2 particles) can have the same location and state at the same time. Photons are spin-1 particles and have the opposite effect: two photons *prefer* to be in the same location and state at the same time - in fact, if you have a collection of N photons in a particular state, plus one additional one, you're N times more likely than classical treatment would have you believe to find that last photon in exactly the same state as all the others.
In a laser you set up a system that will, in time, decay spontaneously. There's a certain probability per unit time that the system will have decayed into one of the zillion atom-plus-photon states available to it. But if you send a bajillion photons past it in a particular one of those allowed states, the atom is a bajillion times more likely to end up in that particular state than any other.
Why is that, you ask? It has to do with symmetries of the Universe. Remember, the way you figure out how *two* identical particles will behave is to first figure out the way *one* identical particle will behave - then each possible state for the *two* particles is the product of the two wavefunctions for each of the original particles. If there are multiple quantum states that can give you the same measurement result, you have to add all the corresponding wavefunctions, *then* square them to get the probability that your system will give you that result.
So far so good? Okay. If the two particles are really identical, then you can't distinguish between the two ways to rearrange them. If a photon gets emitted from an atom, and an identical photon goes by at the same time, you can't tell which photon was which - so you have to add up the two wavefunctions that correspond to those two outcomes. For that special case of the two photons ending up in exactly the same state, you can show (by handwaving, which I'll do in a moment) that the amplitude for the two photons to be in one of those two states (exchanged vs. not exchanged) is exactly twice what it is in the absence of the surrounding photon. So the expected probability for finding a photon in that state is 4x what you started with -- which is very surprising, since there are only 2x as many photons in the system -- each one is 2x as likely to end up in that state, because of the presence of the other one.
| [
"The critical detail of stimulated emission is that the induced photon has the same frequency and phase as the incident photon. In other words, the two photons are coherent. It is this property that allows optical amplification, and the production of a laser system. During the operation of a laser, all three light-... |
why does a balance sheet always balance? | Because you can't print or destroy money. If you're assets increased, you must have paid for those assets somehow - so you have less cash or more debt or whatever it took to get that asset. | [
"The balance sheet is the financial statement showing a firm's assets, liabilities and equity (capital) at a set point in time, usually the end of the fiscal year reported on the accompanying income statement. The total assets always equal the total combined liabilities and equity in dollar amount. This statement b... |
Why can rocket boosters have more than 100% thrust? | 100% thrust was the original specification for maximum output from the rocket. It was later determined it could handle more (up to 104% based on the original 100% definition). | [
"The thrust to weight ratio of rockets typically greatly exceeds that of airbreathing jet engines because the comparatively far greater density of rocket fuel eliminates the need for much engineering materials to pressurize it.\n",
"A variety of other rocket propulsion methods, such as ion thrusters, give much hi... |
How much water is there under the earths surface? Will springs ever stop producing water? |
MS hydrogeology grad student here. I assume you’re asking about fresh groundwater that can be used by people (e.g. not sea water or salty brines). In answer to your first question, a recent study estimated the total groundwater volume with 2km of the earth’s surface (essentially this is the water that is accessible to people) at 22.6 million km^3 (Gleeson et al 2015). This is a huge amount of water, and is many times more than the total volume of fresh surface water (e.g. in lakes and rivers).
Answering your second question about springs and whether we will run out of water is more complicated. Many of the springs on earth are ephemeral, meaning that they can and do stop and resume flowing on a regular basis, usually in response to climate conditions (seasonally dry or wet periods, or longer term droughts or above average rainfall conditions). For the larger springs that flow perennially (year round), going dry is less likely but still possible, particularly in regions where human groundwater pumping from wells is removing significant volumes of water from aquifers feeding the springs.
As to whether or not it’s possible that we run out of water I would say it depends on the region in question and comes down to how much groundwater is being withdrawn by people versus how much is naturally recharging aquifers. In some regions such as the eastern US, recharge far exceeds withdrawals because annual rainfall is much higher in these regions and there is little threat of running out. In the western US the reverse is often true and groundwater is being withdrawn at a faster rate than it is being naturally replenished. An example of this can be found in California, where a historic drought and historically low snow fall in the Sierras has forced many farmers to feed their crops with groundwater instead of surface water. The result of this increased groundwater pumping has been significant drops in water levels and even land subsidence (in some cases as much as 1 ft). This doesn’t mean that California is in danger of running out of groundwater any time soon, just that currently they are withdrawing more than is being put back in. If this practice continues long enough, however, eventually the aquifer would be depleted.
Citation: Gleeson et al. 2015: The global volume and distribution of modern groundwater, Nature geoscience: doi:10.1038/ngeo2590
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"The flow of water from Fossil Springs has been estimated to range from (320–420 gal/s) year-round, and it emerges from underground at a constant . The United States Geological Survey installed a stream gauge at the Fossil Creek Bridge in 2010. The maximum daily discharge at that station was on February 19, 2011, a... |
How much did China contribute to the end of Imperial Japan | I would direct you to my answer on a related question: [How significant was the Second Sino-Japanese War in World War II?](_URL_0_)
It must be emphasised that this is still very much a debated topic among scholars - Western and Japanese scholars tend to downplay the role of China in the larger Pacific War, which I agree with to some extent as seen in the above answer, while Chinese historians tend to emphasise Chinese contributions to the theater. | [
"Japanese investment (private and central government) ran at ¥1,715,000,000 (£171,580.000 sterling) in 1938. In 1941, ¥5,000,000,000 was reinvested—the equivalent of $2 for every person in China. For local and foreign commerce, Japan organized a centralized economic structure, a national central bank and a local cu... |
why are we told leave a pool during a thunder storm if the pool is grounded? | Yes, the pool is grounded, so lightning will pass through it into the ground. You are mostly water. If you are in the water, some of those 1.21 Gigawatts are going to pass through you was well. | [
"Unlike other thunderstorms, which typically can be heard in the distance when approaching, a derecho seems to strike suddenly. Within minutes, extremely high winds can arise, strong enough to knock over highway signs and topple large trees. These winds are accompanied by spraying rain and frequent lightning from a... |
What's that noise I hear when I shut my eyes really tightly? | Congratulations, there are not many people who can flex this muscle at will. I do it sometimes to drown out loud noise. I can basically create a rumbling noise like thunder or a 747 passing, and I can probably hold it for an hour if I wanted to.
_URL_0_ | [
"For a person who tries to actively observe this closed-eye perception on a regular basis, there comes a point where if they look at a flat-shaded object with their eyes wide open, and try to actively look for this visual noise, they will become aware of it and see the random pointillistic disorganized motion as if... |
Any news on the attempt to photograph a black hole? | _URL_0_
It's on the front page right now. | [
"She led the development of an algorithm for imaging black holes, known as Continuous High-resolution Image Reconstruction using Patch priors (CHIRP), and was a member of the Event Horizon Telescope team that captured the first image of a black hole.\n",
"studies into black holes with the goal to construct a blac... |
Is it possible for an environment to be so cold, an existing fire would be extinguished? | Absolutely. The fire needs to be hot enough to be self-sustaining. Each reaction has to give off enough energy to trigger the next reaction. If the surrounding environment absorbs this energy then it is not available to trigger the next reaction.
Just for a simple example, if you've ever tried to put out a fire in a fireplace, you know that the simplest way to do this is to move the burning logs away from each other. Once they are no longer absorbing heat from each other, the fire will dwindle and eventually die without consuming the logs. | [
"In some cases there is sufficient heat, fuel, and oxygen to allow spontaneous combustion and underground fires to smolder for some considerable time, as has occurred at a natural reserve in Spain. Such fires can cause surface subsidence, presenting an unpredictable physical hazard as well as environmental changes ... |
why is going asleep on your stomach so bad for you but feel so good? | If sleeping on your back is *uncomfortable*, maybe you just need a new mattress. If you want to sleep on your stomach, though, know that sleeping on your stomach can put your lower back in an awkward position. If stomach sleeping is more comfortable for you, try sleeping with a pillow under your stomach. That will put your spine in a more neutral position to alleviate the strain. | [
"\"\"We are having a particularly hungry period and [I] can quite truthfully say that our mouths water, and that we 'slaver' as dogs do before meals. Some of us find it advisable to rise slowly after lying down, as due to malnutrition, any rapid movement is apt to cause dizziness or even a black-out ... one morning... |
Did early sailors believe the ocean was an entity that either A) Looked out for them or B) Was out to get them? | Pre-Conversion Scandinavians saw the open ocean personified as a couple of gods; Aegir and his wife Ran. Aegir was the brewer of the gods (with his enormous bubbling cauldron; see the symbolism?) and generally a decent sort.
His wife, however, was known as the seawitch and would cast her net, pulling unlucky sailors to their watery grave. It was said that those who drowned in the open sea went to live with Ran in her hall, much like the modern Davey Jones' Locker.
The sea giveth, with riches and new lands for the taking, and the sea taketh away, with a watery grave.
| [
"Despite all this, human knowledge of the oceans remained confined to the topmost few fathoms of the water and a small amount of the bottom, mainly in shallow areas. Almost nothing was known of the ocean depths. The British Royal Navy's efforts to chart all of the world's coastlines in the mid-19th century reinforc... |
why does stress result in prolonged muscle contractions? (i.e., chronic neck and shoulder pain) | Goes back to the fight or flight instinct.
Stress puts an added toll on our bodies. When you feel fear or anxiousness, you are under stress as well.
Basically its your instincts tensing your muscles to tell your body we need to move and move fast because the situation we're in is dangerous. Stress is prolonged and having your muscles tensed for a while hurts them when they relax, just like lifting weights.
While you may just be under a heavy load at work and not in real danger, your body still reverts back to the instinctive nature. | [
"Chronic stress is the response to emotional pressure suffered for a prolonged period of time in which an individual perceives they have little or no control. It involves an endocrine system response in which corticosteroids are released. While the immediate effects of stress hormones are beneficial in a particular... |
how does silicon and copper and the makeup of a chip ultimately store digital information? | Electronic memory storage at it's most basic has to do with being able to either hold onto some amount of electrons, or get rid of those electrons.
We discovered that if you stick two slightly different types of silicon together in just the right pattern, you can create a little electrical gate. If you shove electrons at the side of the gate, then the gate opens other electrons can pass through it. However if you take electrons away from that first side of the gate, the gate closes and no electrons can get through.
We also figured out that you can use silicon to create a little electron bank. If you want to store data you just line up a bunch of those banks next to a bunch of gates. Each bank is a binary 1 or 0. You use the gates to control which banks get some electrons (a '1') or which bank is drained of its electrons (a '0').
The other fancy thing we figured out is that we can use super tiny photo printers to print a map onto the silicon. Then we blast some junk chemicals at it. The map will block some areas from getting the junk but the other areas get a full dose of junk. These junked and non-junked areas form all of the banks and gates. This makes it *relatively* easy to make tiny processors and other devices. | [
"In the raw file, each of 4.7 million triples of digitized data from the sensor contains three measurements taken at three different depths within the silicon chip. The penetration of light into silicon is dependent on the wavelength of the light; therefore, the red, green, and blue values can be independently calc... |
Decay related: does time (in any scale) have any significance to a stable atom? | It depends on what kind of stable atom you're talking about and whether you mean just the nucleus of the atom or if you include the electrons in the atom.
A large group of nuclei are theoretically stable forever as long as protons do not decay (we think they don't). Some "stable" nuclei are considered stable but actually just have a very long half-life.
Carbon-12 will never decay as long as you do not introduce energy or other particles to it. | [
"Physically, the time constant represents the elapsed time required for the system response to decay to zero if the system had continued to decay at the initial rate, because of the progressive change in the rate of decay the response will have actually decreased in value to formula_1 in this time (say from a step ... |
Does The Endoplasmic Reticulum Transport ATP? | Hi. The ER is used for the transport of proteins and other complex molecules as you mentioned, but that does not really include ATP. ATP, whether it's made by oxidative reactions (glycolysis -- > electron transport chain) or anaerobic respiration, is utilized instantly. Thus, a cell makes ATP *as required*; it isn't transported nor saved for later usage.
ATP doesn't *really* need to travel around cells, since it's used instantly to power reactions that the cell needs. And it's not just made in one location; glycolysis occurs throughout the cytoplasm, which then later shifts to the mitochondria for the Krebs cycle and ETC.
[Source](_URL_0_) | [
"The endoplasmic reticulum (ER) does not harbor an ATP-regeneration machinery, and therefore requires ATP import from mitochondria to exert its biological function. For example, the imported ATP is used for protein folding and trafficking \n",
"Neurotransmitter transport systems are responsible for the release, r... |
if bitcoins have a monetary value, and bitcoin mining earns you bitcoins, how does this mining create any value? | The calculations that are being done secure the network. The cool thing about Bitcoin is that it is a monetary system that is completely decentralized--there are thousands of computers working together to maintain a public ledger of accounts with balances and nobody has authority. That type of system would normally be prone to various types of attack (people modifying the ledger to serve their own purposes). Bitcoin mining acts as a method by which the ledger is allowed to be updated--in order to change the ledger you have to provide proof that you've done lots of very challenging work. This makes it very difficult for someone to, for example, add a transaction to the network where they send money to one person, then go back and change that transaction to say that they actually sent money to another person.
The way this winds up playing out is that someone attempting to put in that type of change has to race the rest of the world. If only a few people are working to secure the network then this is not a very difficult challenge. However, the Bitcoin network could take on every supercomputer in the world at once and still win by a massive margin (it's currently using almost entirely specialized hardware purpose-built for the task).
In order to draw in people to work towards that goal of security a reward is set. New Bitcoins are introduced to the system as a payment to the miners. This is no problem--the whole system is based on rules. Most rules are pretty straightforward--things like "you can't spend more money from an account than that account has," or "you can't spend money from someone else's account (as verified by digital signatures--a powerful tool in modern cryptography)." One of the rules simply states that "new coins are introduced into circulation every time a miner adds a set of transactions to the ledger." It turns out that every bitcoin in existence can trace its roots to this origin.
The value in terms of "real money" then comes from the usefulness of the system--Bitcoins have a number of properties that make them attractive for various uses. Note that when new bitcoins are added to circulation that is a move that is completely independent of any movement of "real money." The bitcoins that are paid out may then be sold for national currencies like the Dollar or Euro, but that gets into gold old fashioned supply and demand--the supply of bitcoins is going up so unless the demand goes up the price will fall. Over the past several years the interest in bitcoin has grown an incredible amount so the price has gone up significantly. | [
"Bitcoin mining is a competitive endeavor. An \"arms race\" has been observed through the various hashing technologies that have been used to mine bitcoins: basic CPUs, high-end GPUs common in many gaming computers, FPGAs and ASICs all have been used, each reducing the profitability of the less-specialized technolo... |
what makes software compatibility between mac or pc so difficult? | Let's say PC is like building with lego, Mac is like building with k'nex. Sure they're both plastic, but lego doesn't fit with k'nex. | [
"Other PC compatibility solutions took a more native approach by running Windows and MS-DOS by using x86 expansion cards with an x86 chip on the card. Apple offered some systems configured this way, marketed as \"DOS Compatible\"—a card with dedicated x86 CPU and RAM was used, while the Mac hard drive, sound subsys... |
What happens if mass defect equals or exceeds original rest mass? | Actually from my understanding (read out of my ass and memory) the mass defect is the minimum energy needed to overcome other force and stay binded together, hence it's other name, binding energy. So this mass defect cannot be augmented by putting the nuclei closer together.
> Any examples theoretically possible in reality?
Yes
> Mass change = (unbound system calculated mass) − (measured mass of system)
> i.e., (sum of masses of protons and neutrons) − (measured mass of nucleus) (Wikipedia yeah I know shame on me)
If you want mass change equal to the unbound system calculated mass then you need mesure mass of system to be 0. So you need the two particle combined to have zero mass. There's an example of that, it's matter and antimatter colliding. The energy didn't disappear it was radiated away in the form of heat and light.
> Also what would the mass defect be for a black hole? e.g. if we squeeze a 1kg object into a BH, what would its mass be?)
You would have a 1kg black hole. By mass defect we mean that the mass changed form and became heat and light or change in velocity or some other kind of energy and subsequently escaped from the system. But in the case of a black hole, it cannot escape in the form of light. Nor heat AFAIK (pulled out of my ass but if it absorb what it touches and cannot radiate light waves, I don't see how it can cool). It could (again a guess from my ass) actually loose some mass in the form of a change in velocity but that would depend on the way you create the black hole.
TLDR yes you can but not the way you think of it. It would mean the end product has no mass. Your black hole has probably 1kg
Please if you are more knowledgeable and see that I made a mistake, correct me for me and for OP knowledge (and all the lurkers out there) | [
"Mass defect is the difference between the mass of an object and the sum of the masses of its constituent particles. Discovered by Albert Einstein in 1905, it can be explained using his formula \"E\" = \"mc\", which describes the equivalence of energy and mass. The decrease in mass is equal to the energy given off ... |
what's benefit do major powers get from donating to struggling countries? | They get influence over that country. Take South Korea for example. After Korea helped their war o their behalf, the US is seen as a powerful country that every Korean highly respects. This country could help the US in the future. | [
"Beyond the incentive compatibility problems that can happen to foreign aid donations –that foreign aid granting countries continue to give it to countries with little results of economic growth but with corrupt leaders that are aligned with the granting countries’ geopolitical interests and agenda –there are probl... |
what is happening in britain's parliament and why did the queen "close" it. | They are starting a new session of parliament after electing a new Prime Minister. In order to do this they have to end the old session and the only way to do that in their system for the Queen to order it. | [
"Until the passage of the Fixed-Term Parliaments Act in 2011, government shutdowns in the United Kingdom were impossible due to parliamentary convention. A government which could not command a majority in Parliament would be dismissed, either prior to the seating of Parliament when the Queen's Speech was voted down... |
What prevents a car/engine from surpassing its top-speed? What's happening when it is reaching that point? | I assume you mean the maximum RPM of an engine? The maximum RPM of a car engine, usually called the redline, is based on a few physical factors.
First, the rotating mass in the engine. High speed rotating things have lots of energy, causing high stresses. Spinning all those components too fast may damage something that wasn't meant to handle the abuse.
Second, the limits on flow. Depending on the design of the combustion chamber, there may not be time to get air into the cylinder, burn it, and get it out if you're doing things too fast. The intake and exhaust components may not be designed for a flowrate higher than the redline RPM.
Third, mechanical issues. The valves may not be designed to open and close properly if they're going too fast. Valves may not close properly if the cam, which controls when they open and close, is rotating faster than the springs and other components are designed for.
It's not an academic source, but [this in Car and Driver](_URL_0_) gives a brief overview. For a more academic source, the issues involved in the valvetrain are briefly discussed in "Design analysis and comparison between standard and rotary porting systems for IC engine" by R. Palmisano and H. D. Ng, available [here](_URL_1_). | [
"If the speed of the car starts to drop below the goal-speed, for example when climbing a hill, the small increase in the error signal, amplified, causes engine output to increase, which keeps the error very nearly at zero. If the speed begins to exceed the goal, e.g. when going down a hill, the engine is throttled... |
the difference between a pothole and a sinkhole | A pothole is a hole that develops in the road. Roads wear over time. Cracks develop and connect, eventually the piece of asphalt becomes loose and falls out, leaving a big chunky hole in the road.
A [Sinkhole](_URL_0_) happens when water erodes the earth below the surface. Eventually the cavity becomes large enough that the land just collapses into the hole. They can be quite sudden. | [
"Whereas a sinkhole is a depression (doline) of surface topography with a pit or cavity directly underneath, a ponor is kind of a portal where a surface stream or lake flows either partially or completely underground into a karst groundwater system. Steady water erosion may have formed or enlarged the portal in (ma... |
What exactly is Gnosticism and how does it differ from Christianity? | Gnosticm isn't a single belief or religion. So it is hard to pin down how it differs from Christianity. Indeed there are even forms of Gnostic Christianity.
It was a general movement in the Mediterranean Basin in the first few centuries CE. The basic point of a gnostic belief, was that there was some special form of knowledge that could provide something for the learner. Gnostic itself is derived from the Greek word for learned or knowledge. So a gnostic was simply someone who claimed to have some sort of knowledge. Exactly what this knowledge was or what it was supposed to do for the learner varied wildly from group to group. For the most part Gnostics believed that their special knowledge would somehow grant them access to special treatment in the afterlife. And usually this knowledge was shared by one deity or another. Most of the Mystery Cults of the early CE era could and sometimes were called gnostic.
And Christianity included gnostic subgroups within it. These were almost religions within a religion where certain individuals would be initiated into he "true meaning" of Christianity. But even within Christianity there were dozens of different sects of Gnostics, all claiming secret knowledge.
Let me give you one example; this should demonstrate the kinds of things that some Gnostics may have believed... but it shouldn't be taken as representative of all gnostic Christian belief, let alone gnostic belief in general, because there is no general gnostic belief.
In this mythology God was complete and whole within himself. But for some reason he divided himself into some of his attributes and gave them a separate existence. He still existed as himself whole and unchanged. But he also now existed as these separate beings as well. In some forms of the story he creates only a few, a dozen, or even up to 300 of these beings. One of these beings was Sophia (Wisdom). And for whatever reason (it differs from version to version) Sophia created an additional being known as the Demiurge.
Now the Demiurge didn't share in Sophia's wisdom. She couldn't impart any of herself. And she also couldn't duplicate any of God's other attributes. But she could emulate them. So the Demiurge got similar characteristics to God, but they were imperfect. Being an imperfect being the Demiurge couldn't perceive God or his attributes (even his own mother). And so he thought he was alone in the universe. To ease his loneliness he created the physical world. Unknown to him the only source of "material" to work with was God. So the Demiurge was taking parts of God and separating them from the whole. With this divine essence he created Earth and Adam and Eve. The Demiurge you see was Yahweh, the god of the Old Testament.
The original God saw this and was sad because parts of himself were now separate consciousnesses; something he approved of. But they were separated from him and ultimately from enlightenment and perfection; which he disapproved of. So he incarnated himself into the material world, as Jesus. When he died and returned to himself he forged a path that would allow all of humanity to follow and reunite with him. He also imparted the secret knowledge of how to follow this path he created to some disciples who then provide this secret knowledge to the rest of humanity.
In some versions ultimately everyone will follow the path back, but by learning and accepting sooner we reduce our suffering. In these versions there is some sort of reincarnation. And the ultimate fate is that the Demiurge will be saved and restored to God as well. In other forms the Demiurge is damned for his actions as are any who don't follow the secret path back to God and his attributes. They ultimately would be destroyed or simply permanently separated from God.
Depending on the details of the belief it could affect behavior. Some Christian gnostic communities encouraged celibacy, believing that by having kids you were stealing some of the original God's essence and adding to the suffering of the world. Others encouraged large families believing that the essence was a set amount stolen in the beginning and by having children in a gnostic family exposed souls to the proper knowledge faster.
Regardless of the details of the specific beliefs of the gnostic groups, other early Christians viewed them as heretics of the most dangerous kind. They denied the saving power of Christ's atonement, placing salvation in secret teachings. So they were firmly opposed. | [
"Gnosticism in modern times includes a variety of contemporary religious movements, stemming from Gnostic ideas and systems from ancient Roman society. Gnosticism is an ancient name for a variety of religious ideas and systems, originating in Jewish-Christian milieux in the first and second century CE.\n",
"The e... |
How many scientists are religious? | Amongst chemists, the percentage of non-religious people is quite high. There are some of everything, of course, but from personal experience there are more atheists than anything else.
There is a good [wiki page](_URL_0_) on the subject.
More than 70% of members of the National Academy of Sciences don't believe in God, 20% agnostic, and 7% believers.
A Pew Study in 2009 found 33% say they believe in god, and yet 48% claim a religious affiliation!
So, the statistics seem to bear out my experience: a minority of scientists are religious, and as the scientists get better, it gets even smaller.
From a personal view, I believe any good scientist is necessarily an atheist/agnostic as it speaks to a deep commitment to reason and data-based decisions. | [
"Prominent modern scientists who are atheists include evolutionary biologist Richard Dawkins and Nobel Prize–winning physicist Steven Weinberg. Prominent scientists advocating religious belief include Nobel Prize–winning physicist and United Church of Christ member Charles Townes, evangelical Christian and past hea... |
Does anyone have information on Georgy Zhukov's service in WWI? | You mean you need to give a speech on him, so, schoolwork? In that case, I'd like to simply point you in the right direction to research this. "Stalins General" by Geoffrey Roberts is the best English language biography on Zhukov. Roberts also is the editor for the most recent English edition of Zhukovs memoirs. Get your hands on those and it covers the topic quite well. | [
"Appraisals of Zhukov's career vary. For example, historian Konstantin Zaleski claimed that Zhukov exaggerated his own role in World War II. Marshal Konstantin Rokossovsky said that the planning and decisions for the battle of Kursk were made without Zhukov, that he only arrived just before the battle, made no deci... |
If two people held a string stretching from one side of the universe to the other, would it snap due to the expansion of the universe? | Yes. There is a real tension on the string from the expansion. | [
"String theory proposes that our universe is merely a 4-brane, inside which exist the 3 space dimensions and the 1 time dimension that we observe. The remaining 7 theoretical dimensions either are very tiny and curled up (and too small to be macroscopically accessible) or simply do not/cannot exist in our universe ... |
is the time +12 hours or -12 hours in the opposite part of the world? | Timezones are very confusing my man I feel you. I say we get rid of them and just all keep one time. Back to your question though. Two things are important to answering your question: the direction of rotation of the Earth/its shadow, and the international date line. We all know the Sun rises and the East and sets in the West, so one could make a logical step to say that people that see the Sun before you (East of you) are living in a timezone before yours. In other words, clocks to the East will always be ahead of yours. This is true in all except one place, at the international date line located between Asia and the Americas in the Pacific. To avoid confusion, cut the globe on this line (quickly) and imagine laying the world flat with the Americas to the West and Asia to the East (like you always see it.) Now you can’t think about it too too hard, but that sheet now represents a day and it works perfectly if you remain static. If you were to cross the line, however the day changes. Let’s say you are watching the sunrise just to the Americas’ side of the date line. You would see the Sun rise up, and that’d be the beginning of your day 1. Just by crossing the date line, suddenly you’d now be at the start of Australia or New Zealand’s day 2. It sounds very strange I know but this is required to make timezones work. Back to the question now that we have the basics. Let’s say you are in Germany. The opposite side of the world for you might be slightly off the coast of California. Because you haven’t crossed the date line you can suppose that their clocks are 12 hours behind yours. (so 0300PM to 0300AM)(1500 to 0300.) Now lets say you want to go from the middle of Canada to somewhere in Southern Asia. There are two ways to do this. The simpler way would be to think to your self that you want to remain on one day, so crossing the date line is not allowed. In that case you’d have to go East and add time, +12hrs. The other way to do it is to always travel Westbound when doing your math subtracting time as you go on, then add 24hrs the instant you cross that perplexing date line. | [
"In several countries the 12-hour clock is the dominant written and spoken system of time, predominantly in nations that were part of the former British Empire, for example, the United Kingdom, Republic of Ireland, the United States, Canada (excluding Quebec), Australia, New Zealand, India, Pakistan, Bangladesh, Ma... |
why sometimes only the back end of the scissors work, sometimes the middle, and sometimes only the tip? | The blades of the two sides of the scissors aren't perfectly parallel. If there's even a small gap, they won't cut very well. This could be due to the scissors themselves, or the blades being deformed slightly by the material you are trying to cut. The tips are easiest to splay apart.
Or the scissors are dull in some places. | [
"The direction of the cut is quite easy to change because of the thinness of the blade. Gentle curves are achieved by slowly turning the whole frame by means of the handle while continuing to cut steadily. When necessary, the blade can also be rotated with respect to the frame to make sharper curves in the material... |
the debate over whether the eu is good | You want the *debate* explained?
Some people think EU is good. Other people think it is not so good. This is the debate.
[Edit] To make this post less worthless - the debate will depend mostly on what country are you talking about. Economically, it is generally considered that EU is more beneficial the poorer the member country of it is, since it can count on the highest funding. Politically it is a whole 'nother mess, but as I understand it Germans run the show. | [
"The EU Institute focuses on topical issues in international commercial law, and European law. The European Union is a major trading partner of the United States and Asia, and as the enlargement process of the EU continues a sound understanding of the many legal and policy questions that arise is imperative for any... |
why does the sound of poured water gets higher and higher as you keep pouring? | Because the sound you're hearing is sound coming out of a round chamber. When the glass fills with water, the size of the chamber changes, so the pitch changes. Large chamber, low pitch. Small chamber, high pitch. It's why digieridoos are deep and rumbly while ocarinas are high pitched and whiny. | [
"Jugs will also produce sound at their main resonance frequency when air is blown across the top opening. This method is not used in bands, since it is relatively quiet and produces only a single pitch. It is typically used for making glass bottles whistle. A larger bottle produces a lower musical pitch while small... |
Do sentience and self-awareness have an evolutionary advantages? If so, what are they? If not, how did they become such predominant features in humans? | You might not have any replies yet because I think you're asking about the [hard problem of consciousness](_URL_0_). | [
"In summary, allorecognition, the ability to distinguish self from non-self, is basic to all life, unicellular as well as multicellular. The earliest recognition systems were innate, and were based on the recognition of self molecules. The evolution of multicellular forms brought about selective pressures for ever-... |
What is the main source of protein for large herbivores? | Many plants have a high protein content. Even grass has a decent amount. Grass seed like oats and barley have somewhere in the ballpark of 8%-10%. Other plants are higher than grass, clover and alfalfa spring to mind. | [
"A large percentage of herbivores have mutualistic gut flora that help them digest plant matter, which is more difficult to digest than animal prey. This flora is made up of cellulose-digesting protozoans or bacteria.\n",
"BULLET::::- Amino acids are the basic components of proteins. Protein requirements vary acc... |
Is donated blood cleaned in any way to prevent the spread of disease? | Blood is transfused (out of the donor and into the recipient) by the unit and each unit of blood is only from a single person. Also, it is all screened, in high income countries, anyhow, for a range of infectious disease including (These are what the Red Cross check for, other organizations test for other diseases): Chagas disease (T. cruzi), Hepatitis B virus (HBV), Hepatitis C virus (HCV 3.0), Human Immunodeficiency viruses, Types 1 and 2 (HIV 1,2), Human T-Lymphotropic virus (HTLV-I/II), Syphilis (Treponema pallidum), West Nile virus (WNV) [Source](_URL_0_).
[World Wide blood testing](_URL_1_) | [
"Donations can also be taken by machines called cell separators, usually in larger blood donation centres located in city centres. These machines use a process called apheresis to collect either blood plasma only, or plasma and platelets, the other blood cells being returned to the patient. Platelets are the tiny f... |
why is it that a rocking motion or a car ride puts my baby to sleep but when i'm in a similar situation it doesn't make me sleepy? | It's not just the rocking motion, it is the constriction of the car seat that doesn't allow him to move coupled with the sound of the car. A car's tires on the road would be a familiar sound to what a baby hears for the entire gestation period. For instance, cup your hands over your ears and you hear the blood rushing through... sound familiar to a car tire on the road?
Those both allow the baby to feel back in the mother's womb. | [
"Many adults find rocking chairs soothing because of the gentle motion. Gentle rocking motion has been shown to provide faster onset of sleep than remaining stationary, mimicking the process of a parent rocking a child to sleep.\n",
"Indian people believe that the rocking motion soothes and relaxes the child and ... |
why do so many homeless people talk to themselves out loud? | They most likely are mentally ill. | [
"There is anecdotal evidence that many Americans complain about the presence of homeless people, blame them for their situation, and feel that their requests for money or support (usually via begging) are unjustified. In the 1990s, particularly, many observers and media articles spoke of \"compassion fatigue\" a be... |
what do they do with money found on/ around dead people at the scene of the crime?(after investigating it) | Give it to the family if the money is “clean”.
If it’s “dirty”, meaning obtained illegally in one way or another, the police department seized it and typically spends it. I know in my area, any drug money seized is put into drug education for students or invested into the departments drug task force. | [
"After money or merchandise has been stolen, the criminal employs a mule to transfer the money or goods, hiding the criminal's true identity and location from the victim of the crime and the authorities.\n",
"However there was little or no evidence found at the crime scene: no blood (except from the victims), hai... |
Why does this flame look segmented? | They're called shock diamonds i believe, and they occur at super-sonic speeds. | [
"The flame is applied to the base metal and held until a small puddle of molten metal is formed. The puddle is moved along the path where the weld bead is desired. Usually, more metal is added to the puddle as it is moved along by dipping metal from a welding rod or filler rod into the molten metal puddle. The meta... |
What kind of lasting impact did the Civil War have on American citizens? How did they cope with such massive scale violence? | I don't have a lot to offer you in terms of new sources, but I was immediately struck by how little you're including Civil War memory in your discussion. It may be that escapism played a role in how the Civil War was portrayed in subsequent decades and even to this day, but debates and interpretations about the legacy of the war and its meaning played an extremely significant role in the war's aftermath and beyond. It's not my specialty so I can't give you too many authors, but David Blight, Gary Gallagher, and Caroline Janney should all be useful. If you want to prove the influence of anything PTSD related, you'll also need to account for other major influences like memory as well.
Also, I don't mean to discourage this project at all, it sounds interesting, but you'll need to be very careful about your source interpretation. As you said, PTSD was probably present but undiagnosed. Anything from your sources which you attribute to PTSD will be a matter of interpretation, and the responsibility will be on you to convince the reader that it wasn't something else. Any cavalier use of sources could be very problematic. | [
"The casualties of American Civil War did more than simply reduce the male population of the country, they also dramatically increased the number of widows and orphans. Many states reacted to the crisis by erecting new (or taking over existing) buildings to \"care for, educate and train the children of fallen soldi... |
The James Webb Space Telescope: Why the gold-coated beryllium reflector? | _URL_0_
> If the Hubble Space Telescope's 2.4 meter mirror were scaled to be large enough for Webb, it would be too heavy to launch into orbit. The Webb team had to find new ways to build the mirror so that it would be light enough - only one-tenth of the mass of Hubble's mirror per unit area - yet very strong.
> The Webb Telescope team decided to make the mirror segments from beryllium, which is both strong and light. Each segment weighs approximately 20 kilograms (46 pounds).
> Once a mirror segment's final shape is corrected for any imaging effects due to cold temperatures, and polishing is complete, a thin coating of gold is applied. Gold improves the mirror's reflection of infrared light. | [
"BULLET::::- Gold is a good reflector of electromagnetic radiation such as infrared and visible light, as well as radio waves. It is used for the protective coatings on many artificial satellites, in infrared protective faceplates in thermal-protection suits and astronauts' helmets, and in electronic warfare planes... |
Why did the French Government regress back to bolt action rifles at the end of the first world war? | The answer is one of doctrine
through most of the second world war, the primary combat weapon for an infantry soldier in almost all armies was a bolt action rifle, in most cases supplemented by a squad/platoon level machine gun section (this varied drastically from formation to formation of course)
the idea was to have the "squad" MG as a suppression weapon to allow for the infantry to maneuver from a fixed anchor point (or two, for example german schewere panzergrenadier formations sometimes had two MG42s at the squad level), this doctrine was largely common to the European combatants, and i believe the french followed along, as they used the Lebel in conjunction with the FM 24/29 (and Brens, and chauchats, and anything they could dig up towards the end..)
for the soviets it was the the Mosin–Nagant 91/30 with a DP mg
for the british it was the Lee-Enfield MK4 with the Bren
for the germans it was the Kar 98k with the MG42 (the GW43 not being issued until 43, and never eclipsing the Kar98 except in mountain and as i recall falshimjaeger units)
for the italians it was largely the Carcano M91/41 with a number of Breda Mgs
only the americans used an "automatic rifle" doctrine, where the Garand was a standard rifle, and the BAR supplemented it (the BAR most definitely not being a full MG), only Armored rifle and Airborne platoons tended to have incorporated light 30cal Mgs. the automatic rifles provided each infantry soldier more individual firepower, and a better individual capability to offer suppression fire, at the cost of not having a lynch-pin squad level MG. (it mostly worked... but like most ww2 american doctrine, it had its major drawbacks... See tank destroyers....)
the automatic rifle was the anomaly, not the standard.
the other side to it is production, as the war dragged on, most combatants started to add more and more automatic rifles into the mix, the SVT rifle became more common, the gw43, etc, but these weapons were in general more complicated to produce, and in most cases, a greater number of bolt-action rifles were preferable, except in the US where production of Garands was sufficient as to not require "dropping down" to a bolt action rifle.
and last, well, frankly, the french military establishment after ww1 was a clusterfuck.. between the maginot line, balkanized weapons production, and scandal after scandal, modernization programs were a very stop and go affair, with semi- automatic rifles inevitably being a victim here.. i still really like "to lose a battle" by Alistair Horne for insightinto the french military pre-ww2
_URL_0_
Edits: formatting and spelling
| [
"After the end of World War I, the French Army sought to replace the problematic \"Fusil-mitrailleur mle 1915 CSRG\" light machine rifle (better known as the Chauchat). French commanders considered standardizing on the American Browning Automatic Rifle (BAR), but eventually required the development of a locally bui... |
Why did the Australians unload their rifles before going 'over the top' at Gallipoli? | They didn’t unload their weapons before “going over the top”. Why would you believe they did? A military rifle such as the .303 Lee-Enfield has the following degrees of readiness:
Unloaded – No round in the chamber and no rounds in the magazine (or magazine removed),
Loaded – No round in the chamber but rounds in the magazine,
Action – A round in the chamber, rounds in the magazine and safety catch at Safe.
Instant – A round in the chamber, rounds in the magazine, safety catch at Fire and prepared to fire.
On a bolt action weapon such as the .303 Lee-Enfield to chamber a round requires the soldier to work the bolt by pulling the handle to the rear and pushing it forward again. The same action is required to remove (eject) either a fired or an unfired round from the chamber and is part of the action required to unload a weapon.
If your belief stems from watching movies such as Gallipoli, it is possible that you have mistaken the action of working the bolt to be unloading the weapon rather than chambering a round, (changing from the Loaded condition to the Action condition). In a movie this action would be for dramatic effect, as soldiers at the front line would almost certainly already have the weapon at the Action condition and in preparation for “going over the top” would simply change to the “Instant” condition by shifting the safety catch.
| [
"When the Australians reached the Ottoman trenches they found them roofed with pine logs with no easy entrance, which had not been identified by aerial reconnaissance during the planning stages. As the Ottoman defenders recovered from the artillery barrage, they began firing at the Australians through specially cut... |
Who are the Rusyns? | "Ruthenia" is a latinized version of "Rus'," which is the root word for "Russia." The chemical element "Ruthenium," for example, is named after Russia.
In practice, however, the word "Ruthenia" came to apply only to lands outside the Romanov Empire. I suspect the ethnonym "Ruthenian" enjoyed more popularity than the placename: it was the German / Habsburg word for people that today are called "Ukrainians." If you look at 19th century Encyclopedias published in German, they refer to Ruthenians; the ethnonym "Ukrainians" doesn't become widespread in German reference works until the twentieth century. At the time, scholars usually saw the Ukrainians as "little Russians," i.e. as a variety of Russians, but German scholars distinguished "Russen" (Russians) in the Romanov Empire from "Ruthenen" (Ruthenians) in the Habsburg lands.
In the twentieth century, a different meaning has become popular. There's also a bit of Ukraine that used to be part of Czechoslovakia, and before that part of Hungary: the district around Uzhhorod. That territory has lots of different names. Two names are "Subcarpathian Rus" or "Transcarpathian Rus" (depending if you are looking at the region from Prague or Kyiv, it's either "on this side of the Carpathians" or "on the far side of the Carpathians"). Another name for this region is "Ruthenia."
There's also a dispute as to whether the Slavs who live in the Uzhhorod district ("Ruthenia") are Ukrainians or a separate people. Those who believe they're a separate people tend to call them "Rusyns." The minority in neighboring Slovakia, and members of that minority are also described as Rusyns. There's a Canadian scholar of Rusyn origin who studies this part of the world named Paul Robert Magocsi. Magocsi argues for Rusyn distinctiveness, so look for his work if you want further information. | [
"The term Rusyns (\"rusyny\") is derived from Rus' (Ruthenia) and has been widely used for centuries for East Slavs inhabiting it. Since the 18th century this term \"came to be associated primarily with those Ukrainians who lived under the Habsburg monarchy, in Galicia, Bukovyna, and Transcarpathia\", and since ear... |
Why are algal blooms bad? Wouldn't they be a major balancing force for rising CO2 levels? | Algal blooms can cause oxygen depletion - which is actually a problem we have righ now around the Danish waters. I can’t really explain much, but [here is a good article explaining it.](_URL_0_) | [
"CO concentrations have been steadily rising for more than two centuries. Increases in atmospheric CO concentration affect how plants photosynthesise, resulting in increases in plant water use efficiency, enhanced photosynthetic capacity and increased growth. Increased CO has been implicated in ‘vegetation thickeni... |
why text messages are limited to 160 characters while multimedia like pictures can be up to 1,000 | Text messages are sent through a protocol called SMS, or Short Message Service. This protocol basically piggy backs on data signals like tower pings (if you've ever had your phone near some speakers that started making funny noises, that's a ping confirming that your phone is communicating with a particular tower)
so basically they just took the garbage message your phone normally sends all the time and made it a form of communication. But these pings only contain a certain amount of data so SMS messages have a character limit.
Multimedia messages on the other hand, have their own purpose built protocol since they were intended to be able to send things like pictures and audio. Pictures and audio take up a lot more data than plain text so if you send just text you've got a lot more room to play with. Try right clicking a picture in Windows Explorer and tell it to open with Notepad to get an idea of the ratio between image/text data. | [
"A single SMS message has a maximum size of 1120 bits. This is important because there are two types of character encodings, GSM and Unicode. Latin-based languages like English are GSM based encoding, which are 7 bits per character. This is where text messages typically get their 160 character per SMS limit. Long m... |
how is it legal tsa offering first class passengers a faster airport security lane? | Are you sure that is what is happening? My boss pays a yearly fee to go through security faster but he also had to go through an extensive background check and interview process to get that luxury. | [
"As the Q400's 360-knot (414-mph, 667-km/h) cruise speed approaches jet speeds, short-haul airlines can usually replace a regional jet with a Q400 without changing their gate-to-gate schedules. Most short-haul routes are less than 350 miles (500 km), so the time spent on taxiing, taking off, and landing virtually e... |
how can kid music be so annoying to adults while children love it? | With a lot of music, there's a kind of tension between what's predictable and what's interesting or novel. Predictable elements are things like chords that are very harmonious and lead naturally to one another, rhymes and predictable themes in lyrics, melodies that match well with the underlying harmony, etc. What makes a lot of music "interesting" is straddling this line between the predictable and familiar and breaking these rules.
For average listeners, music that breaks too many of these rules--lyrics that are nonsensical or bizarre, melodies that don't seem to conform to any patterns, chords that seem misplaced or sound "wrong"--is [very difficult](_URL_1_) and can be [unpleasant to listen to](_URL_0_). Of course, there's nothing **wrong** with music like this, but for many people it's not an enjoyable listening experience.
The flip side of that is that music that doesn't break **any** rules is, well, boring. If every line rhymes just how you think it will, and tells a story about being happy and dancing; if every piece of the melody and harmony progress in exactly the way your mind expects them to...that's not interesting for most people.
Because of their developing brains, their threshold for what can still "break the rules" of music and be enjoyable to listen to are MUCH lower than an adult's. Basically the development we go through that makes children's music less enjoyable is the same kind of development that makes us want to see more complex stories in a film or novel or video game, or that make us enjoy chess more than Candyland. We need more challenge and less predictability from our entertainment than a child does. | [
"Children's music or kids' music is music composed and performed for children. In European-influenced contexts this means music, usually songs, written specifically for a juvenile audience. The composers are usually adults. Children's music has historically held both entertainment and educational functions. Childre... |
How can volcanoes form where there are no plate boundaries? | Couple of options:
1) [Hotspot volcanism](_URL_0_) where volcanoes erupt above a localized zone of anomalously hot mantle. These are most likely related to [mantle plumes](_URL_2_), but a few holdouts still argue for alternative mechanisms. Regardless, hotspots can occur near plate boundaries (e.g. Iceland) or in the middle of plates (e.g. Hawaii).
2) Plate boundaries are a bit more diffuse than many people realize. There can be a lot of activity even relatively far away from the formal plate boundaries. As an example, the formal plate boundary between [Arabia and Eurasia](_URL_1_) is in northern Iraq, but there is extensive volcanism throughout eastern Turkey, Georgia, Armenia, Azerbaijan, and into Russia (in some cases 1000+ kms from the plate boundary) that is associated with the collision between Arabia and Eurasia.
3) Just because something isn't a plate boundary now, doesn't mean it wasn't a plate boundary in the past. This is the relevant answer for your example question. Specifically, Edinburgh castle is [built on top of 400-300 million year old volcanics](_URL_4_). At this time, this portion of Scotland was along a plate boundary, e.g. [the Devonian period of Scotland](_URL_3_). | [
"Movements of tectonic plates create volcanoes along the plate boundaries, which erupt and form mountains. A \"volcanic arc system\" is a series of volcanoes that form near a subduction zone where the crust of a sinking oceanic plate melts and drags water down with the subducting crust.\n",
"On Earth, volcanoes a... |
Are human beings a particularly diverse species? It seems that we have a big range of physical characteristics and mental prowess while other species are much more homogeneous. | No. We're not all that diverse. Not much more than other animals anyways. *We* see these differences, because those are differences we use to identify individuals, and many of those differences are a result of nurture, rather than nature. | [
"Non-human primates and humans have been observed to be very similar in terms of personality, such as chimpanzees having “’Big Five’ personality factors found in humans, i.e. neuroticism, extraversion, openness, agreeableness, and conscientiousness”. Primates seem to possess a sixth personality trait, dominance. Ch... |
how does a penis triple in size while erect? | Human skin has a natural elasticity, like a rubber band, and can stretch a little, or a lot, depending on the area. The extra mass that fills the skin is blood within the veins and muscle. That’s what ‘engorged’ means. When you’re not excited there’s less blood flow to the area so it’s in the rest of your body doing other stuff. | [
"Generally, the size of an erect penis is fixed throughout post-pubescent life. Its size may be increased by surgery, although penile enlargement is controversial, and a majority of men were \"not satisfied\" with the results, according to one study.\n",
"A statistically significant correlation between penis size... |
; why is theory of everything so elusive? | If anyone actually knew the answer, they'd be spending the rest of their lives getting free sexual favors from every theoretical physicist on the planet. It's impossible to answer because no one knows. | [
"Stanley Jaki, in his 1966 book \"The Relevance of Physics\", pointed out that, because any \"theory of everything\" will certainly be a consistent non-trivial mathematical theory, it must be incomplete. He claims that this dooms searches for a deterministic theory of everything.\n",
"“[A] scientific theory is so... |
why do ants take very roundabout routes to get from a food source to the colony? | > This method of locomotion seems very inefficient, so why do they do it?
An ant has a brain of only about 250,000 cells, compared to our 10,000,000,000 cells. They aren't that smart, and they don't have very good eyesight so they navigate largely by scent trails. Their behavior might be less than optimal but it works based upon very simple nearly automatic instincts, so what do you expect from them? | [
"In the natural world, ants of some species (initially) wander randomly, and upon finding food return to their colony while laying down pheromone trails. If other ants find such a path, they are likely not to keep travelling at random, but instead to follow the trail, returning and reinforcing it if they eventually... |
Where could I find a condensed history of the world? (perhaps not phrased very well) | If you can get access to them, the [Cambridge Histories Series](_URL_0_) is generally very good and covers a wide variety of geographic regions, time periods and areas of study. It's worth checking to see if you can find a library that will provide you online or physical access, because they are quite comprehensive, and if you would like to do any further reading, they will be able to point you towards other works on the topics you're interested in. | [
"BULLET::::- Ellis, Edward Sylvester (1913). \"The Story of the Greatest Nations: A Comprehensive History, Extending from the Earliest Times to the Present, Founded on the Most Modern Authorities Including A Complete Chronology of the World and a Pronouncing Vocabulary Of Each Nation\". New York, NY: F.R. Niglutsch... |
why are the gender divisions in choruses? wouldn't you get a fuller sound from integrated choruses? | Also, it's much more challenging for individuals to stay on pitch and in tune when surrounded by others singing different tunes. Keeping the voices together helps everyone song the right notes. | [
"One Voice Mixed Chorus unites gay, lesbian, bisexual, transgender people and straight allies to build community by raising their voices in song. It is one of the largest LGBT choruses in North America, the 100 singing members range from ages 17 to 75, and the “Fifth Section” boasts more than 50 non-singing volunte... |
If everyone in the world gave up smoking, what would be the impact on global pollution? | ***Edit: this calculation has several mistakes that led to this answer being wrong. [See here](_URL_3_) for a better estimate***
There are [about 5 billion cigarettes](_URL_0_) produced each year.
To look at the impact on pollution, let's look at one specific type of harmful pollution: [PM_2.5](_URL_2_), or small particles less than 2.5 micrometers across. This type of pollution is one of the most important for impacts on human health.
Each cigarette weighs [1.5 grams](_URL_4_), so assuming that each cigarette is entirely burned and turned into particulate matter, this will add 7.5 million kilograms of this type of pollution to the atmosphere.
Now this might seem like a big number, but it really isn't: The average concentration of PM_2.5 in the lower atmosphere is [about 10 micrograms per cubic meter](_URL_1_). Knowing that the surface area of Earth is about 5 x 10^14 m^2 we can then see that the mass of PM_2.5 pollution *in just the lowest 1000 meters* of the atmosphere is 5 **billion** kg.
So let's review:
* We assumed that every manufactured cigarette is completely smoked (likely a vast overestimate)
* We assumed that the smoked cigarettes were entirely converted into particulate matter (also a vast overestimate)
* We assumed that all the cigarette pollution was confined to the lowest 1 km of the atmosphere (pollution is typically very well mixed at least up to 10 km)
* And *even with all these gross over-estimates*, the figure we came up with for cigarette-related pollution was *only 0.1%* of the total type of *this one particular type of pollution*.
~~tl;dr: I think it's safe to say that there would be no discernible direct impact on air quality if all smoking were to stop tomorrow.~~ | [
"The United Nations’ World Health Organization projects that a billion people will die prematurely from smoking this century. In the next 20 years, there will be nearly 1.6 billion smokers around the world. \"A Billion Lives\" takes a critical look at the history of smoking and the corruption that has led to the cu... |
How the image of our galaxy is calculated and how accurate it is? | Images [like this one](_URL_3_) are built from a mixture of things.
First and foremost they are drawn under the assumption that the Milky Way is a lot like other nearby galaxies, so how they look is a useful guide to what the Milky Way would look like from outside.
Then different known parts of the Milky Way are put in. We know there's a [fat bulge-like bar component of our Galaxy](_URL_0_), and we know its rough size and alignment so that gets put in. We know that there's a [longer, thinner bar](_URL_1_) at a similar angle as well, so that gets put in.
We know that the bulk of the stars are in a disc, and we know that it has spiral arms. We have some information about where those are from [a variety of sources](_URL_2_). Measurements of gas velocities give us indirect information, as does observed Milky Way star counts at infrared wavelengths (IR is less blocked by dust) as we look at different lines of sight through the Galaxy. The most exciting source of information is from objects known as [maser sources](_URL_4_) which can be viewed to such high accuracy by radio telescopes that we can determine the distance to them very accurately from their parallaxes. These masers are expected to lie mostly within spiral arms.
Putting all of this information together can give the artist information about where the spiral arms might lie. This information is mostly about the spiral arms on the Sun's side of the Milky Way - on the far side a lot of extrapolation is required.
The details of what these spiral arms then look like (as opposed to where they are) is almost entirely artistic license, guided by observations of other galaxies to give them an idea what to expect. | [
"Images were taken using a photometric system of five filters (named \"u\", \"g\", \"r\", \"i\" and \"z\"). These images are processed to produce lists of objects observed and various parameters, such as whether they seem pointlike or extended (as a galaxy might) and how the brightness on the CCDs relates to variou... |
why did we wait so long to draw attention to china's (and other countries') air pollution problems? | They have been a problem for a while, don't you remember the 2008 olympics? Why do you think this is a new issue? | [
"In 1997, the World Bank issued a report targeting China's policy towards industrial pollution. The report stated that \"hundreds of thousands of premature deaths and incidents of serious respiratory illness have been caused by exposure to industrial air pollution. Seriously contaminated by industrial discharges, m... |
Do birds avoid clouds? | I know that soaring birds (vultures, hawks, etc.) will often seek out the right sort of cloud because it indicates a thermal (rising column of air) that they can use to climb without much energy. However, in this case climbing into the cloud would be avoided since it is--very simplified--the marker of where the thermal stops. | [
"Flight in these birds is almost purely confined to reaching their roosting areas at sunset in trees or any other high and relatively safe places free from ground predators, and for escape from immediate danger through the day.\n",
"These birds forage in soft mud, probing or picking up food by sight. They mainly ... |
Could Hawking radiation cause black holes to stop being black? | > gravitational field stops being greater than the speed of light?
Gravitational fields and speeds are not comparable quantities.
> Or is space-time in black holes so skewed that this couldn't happen?
Inside the event horizon, there are no physically realizable directions that reduce your distance from the singularity. This is true regardless of the size of the event horizon as measured by an outside observer.
> Could Hawking radiation cause black holes to stop being black?
A black hole exhibits black body radiation, and so (if they're hotter than their surroundings) they 'glow' according to the black body spectrum. However, the temperature of a black hole is inversely proportional to its mass: the bigger a black hole, the colder it is. A stellar mass black holes is *well* below the temperature of the cosmic background radiation, and so isn't radiating. That said, if a black hole got small enough that it *did* start to radiate, it would lose mass, which would increase the temperature, which would increase the intensity and frequency of the radiation, which in turn would cause the mass to decrease, and so on. Eventually, it will become small enough that it will radiate in the visible spectrum for a while before it passed off into x-rays and gamma radiation.
[edit]
I checked the calculations using [Wien's law](_URL_1_) and the formulae for [black hole temperature and evaporation time](_URL_0_); it looks like a radiating Schwarzschild black hole would spend around 10^35 years in the visible spectrum, during which time it would have a mass in the range of 10^19 kg (or about 1/5300 the mass of the moon) | [
"Hawking radiation is black-body radiation that is predicted to be released by black holes, due to quantum effects near the event horizon. This radiation reduces the mass and energy of black holes, causing them to shrink and ultimately vanish. If black holes evaporate via Hawking radiation, a supermassive black hol... |
why do we only get "infected" by bad bacteria? why aren't there positive infections? | There are. In fact, by cell count, you are far more bacteria than you are human. Your stomach is full of bacteria that helps you digest, giving you more energy. Unfortunately, antibiotics are indiscriminate and hurt them too. | [
"Bacterial and viral infections can both cause the same kinds of symptoms. It can be difficult to distinguish which is the cause of a specific infection. It's important to distinguish, because viral infections cannot be cured by antibiotics.\n",
"Infections may be caused by bacteria, viruses, fungi, and parasites... |
Why doesn't the wavelength of light affect light speed? | The wavelength is not the motion of a photon. It's the peak-to-peak distance of the maximum amplitude of the electric field (see [image](_URL_0_)). The motion is always perpendicular to both the electric and magnetic fields. So, the light wave is not moving up and down but along the red axis. The speed is equal to frequency x wavelength, and so for light, if the wavelength increases, let's say, the frequency will drop (how fast it cycles through one wavelength).
> Also, since there are energy waves that move faster than visible light, such as ultraviolet light, X-Rays or Gamma rays... how is light the fastest measure of speed?
This is not true. All of them move at the same speed (in a vacuum). How rapidly the electric and magnetic fields fluctuate is what changes. | [
"Another reason for the speed of light to vary with its frequency would be the failure of special relativity to apply to arbitrarily small scales, as predicted by some proposed theories of quantum gravity. In 2009, the observation of the spectrum of gamma-ray burst GRB 090510 did not find any difference in the spee... |
why does blizzard take _url_0_ offline every other tuesday for maintenance, yet most other game services never go down? | Most major mmos go down regularly for patching. Most mobas do as well. | [
"On November 30, 2018 the servers were shut down, citing the license running out and the game making barely enough to keep the servers running. Due to the license only allowing online games, the game needs the servers to work, even in a 'play alone' mode, using NPCs instead of other players in the mission.\n",
"T... |
why do human eyes turn red when a flash is used but dog eyes turn green? | We have slightly different retinas than dogs do. Dogs have the ability to see in very low lighting because what appears green is a layer in their eyes that reflects light within the eyeball in order to increase the amount of light that hits the photoreceptors. Humans lack this adaptation but many other vertebrates have it. The red is most likely just a reflection of blood vessels. | [
"The red-eye effect in photography is the common appearance of red pupils in color photographs of the eyes of humans and several other animals. It occurs when using a photographic flash very close to the camera lens (as with most compact cameras) in ambient low light.\n",
"In flash photography the light of the fl... |
Was there any kind of precursor to the modern anti-vaxxer movement? | Yes, anti-vaccination has a long history. After vaccination against smallpox was made compulsory in 1853 in the UK an anti-vaccination movement grew up calling for an end to compulsory vaccination. This movement was much more widespread than the anti-vaxxer movement of today, lasted for decades and spread to other countries. In Stockholm in 1872 only 40% of the population was vaccinated as opposed to 90% in the rest of Sweden - then there was an epidemic in 1874 which frightened people into sense. The anti-vaxxer movement was so strong that in the UK in 1898 'conscientious objection' was enshrined into law for the first time due to their efforts. _URL_1_
Rider Haggard wrote an interesting novel in 1898 called 'Doctor Therne' about an Andrew Wakefield-like charlatan of the anti-vaxxer movement. When I read it when I was a kid I never imagined that anti-vaxxers would reappear, it seemed so crazy.
_URL_0_ | [
"In February 2019, Zedler came out supporting the anti-vax movement by introducing a Texas bill that would allow parents to opt out of school vaccination requirements. He was quoted as saying “They want to say people are dying of measles. Yeah, in third-world countries they’re dying of measles. Today, with antibiot... |
Willpower and ability to focus are finite resources. So is there anything I can do to "recharge" them faster? | Roy Baumeister is a prominent researcher of willpower and was one who put forward the hypothesis of willpower being a limited resource and I wrote a small paper on this topic for undergrad. That said, my understanding is not very thorough and is limited. He publishes frequently so, if you have access to JSTOR, you should find many papers.
Glucose seems to replenish willpower, though this isn't without controversy. In the experiment, participants would work on tasks until their willpower was depleted. Lemonade was given to the experimental group, I'm not sure what the control group was given, but those given lemonade had a greater replenishment of will-power.
There's other supporting evidence of glucose having an effect on willpower, more specifically self-control. Juvenile offenders were found to have lower blood-glucose levels than non-offenders on average. I don't think this was one of his studies, but someone else's.
Nonetheless, dietary habits have been linked to willpower and self-control in other ways. Those in gangs have poor diets, consisting of mainly fast food, and those in gangs eat that food at erratic hours. Somehow, if I remember correctly, those who were not permitted to get something to eat while hungry were likelier to commit acts of aggression, such as moving into to enemy turf to taunt, but I could be mistaken about that.
Sleep is an obvious replenisher. Throughout the day, a person's willpower wanes and diminishes. It restores after sleep and is at its highest point on average after awaking.
Exercising small acts of self-control also increase willpower. There seems to be a transfer effect where, when a person exercises self-control over one domain, they become more likely of exercising it over others. Two of the small acts I recall being used as examples are deliberately using the non-dominant hand more often--for instance, brushing your teeth with the non-dominant hand or opening doors with it--and the other was modifying one's speech--for instance, stopping the use of filler words or being grammatical in verbal communication.
The folk notion of willpower being like a muscle does have some truth to it. There are other potential reasons contributing to why exercising small acts of self-control would enhances one's ability to exercise self-control. An example of that is that when a person successfully controls herself, a belief in her ability to control herself greatens, and with that belief, her actual ability does also.
I believe there has been challenges to the notion of will-power as a limited resource. There is evidence, from experimental studies, suggesting that only those who have a belief to the effect that willpower is limited resource suffer from its depletion.
Unfortunately, I'm not finding my bibliography, or even the paper, in my saved documents. I also don't have access to JSTOR presently. I understand if this is of removable quality, considering the lack of sourcing. Again, if this is removable, I understand. | [
"The willpower paradox is the idea that people may do things better by focusing less directly on doing them, implying that the direct exertion of volition may not always be the most powerful way to accomplish a goal.\n",
"Kelly McGonigal defines willpower as \"the ability to do what you really want to do when par... |
Are some people actually 'big boned'? | Everyone, please, if you are going to comment, leave your personal histories out of it. Make it scientific and leave sources where appropriate. | [
"We have, consequently, in the clearest cases a lean narrowly-built man: with narrow shoulders, with thin muscles, delicately boned hands, with a narrow, long, flat chest, on which we can usually see the ribs.\n",
"I'm a big guy, I stand at 6' 5\". When I was working out with a friend who was 5'7\" we both were w... |
Soviet POWs in Great Britain during WWII? | According to the [plot summary on IMDB](_URL_0_) the character is a Russian who had been fighting for Germany, rather than a Soviet soldier, who apparently feared extradition to the USSR (can't say I blame him). | [
"From 1942 onward, Soviet POWs were viewed as a source of forced labour, and received better treatment so they could work. By December 1944, 750,000 Soviet POWs were working, including in German armaments factories (in violation of the Hague and Geneva conventions), mines, and farms.\n",
"Sixty percent of Soviet ... |
Given the nature and quantity of Pompeii's graffiti, it is plausible to assume a high rate of literacy? | Possibly, but not necessarily. If we look at the sheer number of graffiti and the fact that many of them are of vulgar (in the linguistic sense, not the weird way that contemporary English uses the word) and use those as more or less the sole criteria, sure. But there's a lot more that's implicit here than what you're suggesting we look at.
Yes, much of the graffiti at Pompeii is vulgar in nature. However, while the sensationalist graffiti with which you--and most other people on the internet--are familiar often deal with the sexual, the taboo, and the "common," that only accounts for some of the graffiti at Pompeii, and they're not even the majority of extant inscriptions. The vast majority of graffiti at Pompeii are only a couple words long, typically just names or are like CIL 04, 02227, which is just the word "Victoria" scrawled onto a wall. Many of the graffiti at Pompeii are nothing but pictures, which can be hard to track down since you won't find them in the CIL. An entire class of graffiti at Pompeii are just tally marks scratched into walls or blocks. Inscriptions like CIL 4.8185 (Mula fellaat [A]ntoni/Fortunata a(eris) a(ssibus) II, "Mula [lit. "the she-mule," obviously not a real name] sucks dick(?) [A]nton(ius?). Fortunata for two bronze asses") are not nearly as common as clickbait articles and undergraduate courses would have you believe.
Most, then, of these graffiti do not even indicate literacy at all. Since most are only a word or a couple of words, or straight up just a picture, we cannot determine whether the inscriber had a full grasp of written language, whether he or she (almost all identifiable graffiti at Pompeii are written by men, which seems relevant to the problem of literacy) had "functional literacy," or whether the inscriber was effectively illiterate but knew enough to write his name or a word or two. Of "full size" graffiti, that is those that contain full sense units and aren't just a word or two scratched onto a wall, almost all do not indicate clearly the social position of the inscriber(s). In the nineteenth century it was a common belief that the wealthy population of Pompeii fled the city after the 62 earthquake, leaving it entirely in the hands of the poor. This is known not to be remotely true now, but the evidence that scholars a couple centuries pointed to was the enigmatic trash heaps that surround the city walls, the gladiatorial riots of 59 that were thought to be the original impetus for the wealthy flight from the city, and the large amount of graffiti, which was assumed could only be the work of the lower classes.
However, when we actually examine the graffiti we find that those graffiti that might potentially be identified with a social class do not necessarily line up with the lower classes. The most obvious type of this class of graffiti is of course the electoral notices (programmata) posted all over the city, which could not have been put up by random people walking the streets. However, a large group of Pompeii's longer inscriptions is the verse inscriptions. These are a mixture of original compositions and citations of great authors. That these are clearly highly learned inscribers is probably beyond question. One graffito (CIL 4.1520), for example, famously combines two modified lines of Propertius and Ovid to create a new epigram. The inscriber must have had a good knowledge of the corpora of both Ovid and Propertius, as well as an understanding of poetic meter and style, and the skill not only to combine the two lines but actually to modify them so that they created two new lines. As if that weren't enough, the graffito is from the Casa degli Scienziati, a high-end residence in the city. Which means that unlike CIL 4.1893-1894, which similarly combines a Propertius poem with an Ovid poem in the same hand but was found on the wall of the basilica, CIL 4.1520 must have been scratched by somebody who had access to the inner areas of this very expensive house. The picture of the inscriber, then, must be of somebody closely connected to the owner of the house and very learned, whether this means he/she was a fellow wealthy landowner or a well educated client. CIL 4.1520 is not alone--a huge quantity of Pompeian graffiti is found within expensive private residences.
A particularly famous example is the collection of graffiti found on the stairwell of the House of Maius Castricius, a high-end urban residence. Here some *eleven graffiti* are scrawled into the same space, many of them referring to each other and the majority of them in verse. The graffiti here present an example not only of the same phenomenon as CIL 4.1520, but also an indication of something that CIL 4.1520 only hinted at. The coupling of Propertius and Ovid in CIL 4.1520 is echoed by CIL 4.1893-1894, but they're not the same poem. However, several of the graffiti at the House of Maius Castricius are identical in text, though not in hand, to inscriptions found all over the city. "Venimus hic cupidi" (we came here desiring) is found at another nine locations in the city. "Quisquis amat valeat" is found at another twelve locations. And neither of these lines stands alone, they make up larger poems that include original lines. What this suggests is that a culture of graffiti existed at Pompeii among some section of learned people. Part of this culture was the construction of elaborate dialogues, similar to those that we find on the walls of shops in prose but more closely relate to the "capping" of songs sung at symposia, in that they are demonstrations of the inscriber's education. Increasingly scholarship is finding that inscriptions at Pompeii, while not necessarily directly referring to each other, form a part of a graffiti culture that appears too elaborate and often too educated to be simply the product of random poor people walking by.
That there might be a unique graffiti culture at Pompeii is perhaps not too surprising. Our evidence for graffiti elsewhere is lacking, and cultures of public (and at Pompeii, also private) inscribing are very different across time and place. Anyone who's been to Rome will have seen, though perhaps not realized what they were looking at, cantos of Dante spray-painted on walls, and the walls around the university at Naples mix political murals, passages from Marx, insults towards the authorities, and raunchy addresses towards girls (and boys). Similarly, graffiti take recognizable forms at Pompeii, and are often quotations of other graffiti. They're also found at specific spots, clustering around shops, basilicas, the amphitheater, and private homes. The location of graffiti, and the fact that they usually come in groups, suggests that location is every bit as important in the meaning as content. This seems self-evident--the crap you'll find on a public bathroom stall in Harlem is not going to serve the same purpose as a big political mural on the side of a public building in Chicago--but it's too often overlooked by people who look at Pompeian graffiti and are amused by how raunchy and vulgar it is. The mere fact of graffiti is not sufficient to determine the social position or education of those who write it. Nor is the content of graffiti necessarily sufficient to demonstrate the same things. The Pompeian evidence on that front is, therefore, somewhat inconclusive.
One final note. I, like many epigraphers (Greek epigraphers at least), tend to argue for a much higher literacy rate than many classicists. That observation of a complex graffiti culture that we cannot really understand may be enough to argue for a more complex picture of literacy, if not necessarily proving a higher literacy rate, is perhaps best shown not by Pompeian evidence, but Archaic Athenian evidence. For a very long time the dominant argument was that Athenian literacy was unusually high, elevated by the democracy, which promoted literacy in its citizens and which employed publicly posted written inscriptions much more freely than most cities. However, around ten or fifteen years ago Merle Langdon started finding graffiti in the rock faces in the countryside way out in rural Attica from the Archaic Period. Langdon has since found more than *two thousand* of these things in the rocks in rural Attica. Compare that to the 11,000 graffiti at Pompeii, a much denser, more educated, more developed area and the achievement is put into perspective. Almost all of these inscriptions are written by shepherds talking to each other, and unlike Hesiod's persona that he's just a rustic Boeotian farmer these are unlikely to be a poetic persona. There are so many hands, the spots are so remote--it's hard to imagine landowning elites going out there to write their names--, and the majority of the inscriptions are just alphabets or notices of people's names. But these inscriptions also demonstrate that already in the Archaic Period at Athens there was a developed graffiti culture way out in the Attic countryside among the herdsmen, who write messages (often quite mean or sexually demeaning) to each other. The cases are not parallel, in that one is a rural society just on the cusp of literacy, whereas the other is a heavily urbanized society long after literacy had taken hold, but Langdon's evidence suggests that there is a place for graffiti in understanding the literacy of the ancient world. | [
"Historic forms of graffiti have helped gain understanding into the lifestyles and languages of past cultures. Errors in spelling and grammar in these graffiti offer insight into the degree of literacy in Roman times and provide clues on the pronunciation of spoken Latin. Examples are \"CIL\" IV, 7838: \"Vettium Fi... |
how do they program traffic lights? how do they coordinate a grid of traffic lights so traffic flows properly? | It used to take a *lot* of exhaustive studying of traffic patterns to keep traffic lights programmed properly to keep jams to a minimum; lights in this system have intervals that are set ahead of time.
These days lights are increasingly controlled by computers. For this, there are induction sensors buried under the road surface that can sense the presence of cars and then a controlling computer that changes the lights based upon road usage rather than at set times.
This method allows dynamic adjustment to traffic conditions, which reduces jams. | [
"Lane control lights are a specific type of traffic light used to manage traffic on a multi-way road or highway. Typically they allow or forbid traffic to use one or more of the available lanes by the use of Green lights or arrows (to permit) or by red lights or crosses (to prohibit). When used, they are usually re... |
what is it about tomato based sauces that makes it a destroyer of tupperware in the microwave? | They are getting stained by Lycopene that ends up in the porous plastic.
You can denature it with a soak in a peroxide solution, they will oxidise and become free of color. | [
"Just like tomato puree or tomato paste, tomato sauce may be one of the ingredients in other dishes, like a tomato-based soup. The sauce is thinner than either the puree, or the paste (which is the thickest), and it may have additional flavors.\n",
"In the U.S., \"tomato sauce\" refers to two distinct sauces. One... |
Is it possible to see the moon become a new moon? | A thin waning crescent Moon always rises during dawn twilight. It becomes a New Moon and waxing crescent once it passes through conjunction with the Sun. This always happens within 5° of the Sun, usually much closer. So the minimum crescent is razor thin and totally invisble in the glare of the Sun.
The moment that the old moon becomes a new moon is really only visible in the path of totality during a solar eclipse. | [
"In astronomy, the new moon is the first lunar phase, when the Moon and Sun have the same ecliptic longitude. At this phase, the lunar disk is not visible to the unaided eye, except when silhouetted during a solar eclipse. Daylight outshines the earthlight that dimly illuminates the new moon. The actual phase is us... |
how did teeth change throughout history? | Forcing teeth straight, unless the situation is truly physically detrimental, is usually cosmetic. It's culturally pushed hard in North America. I've heard part of the stigma that British have bad teeth is just that they don't see the need for the massive expense of braces and over whitening their teeth for beauty. Their teeth are still functional and healthy too. | [
"Tooth eruption is a process in tooth development in which the teeth enter the mouth and become visible. It is currently believed that the periodontal ligament plays an important role in tooth eruption. The first human teeth to appear, the deciduous (primary) teeth (also known as baby or milk teeth), erupt into the... |
To reach speed of light you need crazy amount of energy so Does light actually travels with the speed of light or slightly less? | This is the speed light travels at.
For an object with non-zero mass, it would take infinite energy to get it to the speed of light, which is one way to understand why that can't happen.
But for photons (the particles of which light is made), things are different. Photons have no mass, which turns out to mean they always have to travel at the speed of light. From the moment they are created to the moment they are observed, they travel at the speed of light. | [
"This constancy of the speed of light means that, counter to intuition, speeds of material objects and light are not additive. It is not possible to make the speed of light appear greater by moving towards or away from the light source.\n",
"As speeds approach that of light, the acceleration produced by a given f... |
why does poking a bruise sometimes feel good even though it’s painful? | The pain and pleasure centers of the brain are right next to each other, and mild pain can cause them to get "confused" (as far as I understand it).
It's the same reason why some people like spicy foods and spanking in bed. I'm guessing that how masochistic you are is determined by how easily your pain and pleasure centers get confused. | [
"A bruise, also known as a contusion, is a type of hematoma of tissue, the most common cause being capillaries damaged by trauma, causing localized bleeding that extravasate into the surrounding interstitial tissues. Most bruises are not very deep under the skin so that the bleeding causes a visible discoloration. ... |
why, with the thousands and thousands of possible number/letter combos, would 2 license plates in the same area be even remotely similar? | The numbers aren't random, there are patterns that relay certain informaiton about location, time registered, etc. Though its not universal, and I couldn't tell you what those patterns in canada mean, its likely there is a non-random code used to determine them. | [
"Formats for license plate numbers may be consistent within the state. For example, Delaware and Rhode Island were formerly able to use six-digit all-numeric serials due to their low respective populations; both now use five-digit serials, with Delaware using a letter and four digits, and Rhode Island using two let... |
can anyone explain what happened here on scientific level | Air has weight, and there is miles of it. We have "air pressure" that is the air above is pushing on everything and the air at ground level is pushing back.
If you remove the air at ground level you suddenly get a few miles of air above that spot trying to crush something and just a fraction of an inch of steel trying to prevent that. | [
"A worldwide scientific conference is taking place in Sydney, Australia when Dr. Austin Shepard (Peter Fonda) suddenly disappears. Dr. Shepard's colleague, Christopher Richardson (Luke Perry) and other individuals are soon faced with the reality of an impending crisis and an attempt to keep the information from the... |
when terminally ill patients want to be euthanized what substance is injected for them to pass away and why does it kill them? | Secobarbitol as a capsule, pentobarbitol as a liquid. Both are barbiturates.
Low does of secobarbitol is actually used for insomnia and anxiety.
Makes you sleepy, then you sleep. Your central nervous system becomes depressed, leading to brachycardia and brain death.
Basically everything slows down until you die.
Works by 'enhancing the GABA neurotransmitter in the brain.'- _URL_0_ | [
"Lethal injection has also been used in cases of euthanasia to facilitate voluntary death in patients with terminal or chronically painful conditions. Euthanasia can be accomplished either through oral, intravenous, or intramuscular administration of drugs. In individuals who are incapable of swallowing lethal dose... |
wrinkle-free clothing. | Extremely short answer. Plasticity - some things can be bent over on themselves and some cannot. Wrinkle free material is not bothered by bending, like a rubber band. | [
"Wrinkle-resistant fabrics are textiles that have been treated to resist external stress and hold their shape. Clothing made from this fabric does not need to be ironed and may be sold as non-iron clothing. While fabric cleaning and maintenance may be simplified, some wearers experience decreased comfort.\n",
"In... |
If I lived in western Africa during the height of the Atlantic slave trade, how likely is it that someone I know was captured and shipped to the Americas? Was there a drastic change in culture as a result of the massive loss in population? What societal impact was there? | **The Atlantic slave trade had a catastrophic and permanent effect on western and central Africa.** One of the common misconceptions (and one repeated in a now-deleted comment) is that a slave trade already existed in Africa, so the trans-Atlantic trade couldn't have had significant negative effects. That's entirely wrong. To give an analogy, it's like comparing the quilts your grandmother sells on Etsy with the product of Pendleton Woolen Mills. They operate on entirely different scales.
One of the things you'll read again and again when you study the history of the trans-Atlantic slave trade is the idea that it was a "transformative event." The transformation thesis says African slavery over the past millennium (this includes the Islamic slave trade) has altered African history more than any other event.
Just look at the scale of the trans-Atlantic trade: 5.5 million slaves to Brazil, 6 million to the ~~British~~ Caribbean and Guyanese colonies, half a million to the North American mainland. If you imagine a West African population of 50 million in the 18th century, this is an extraordinary fraction of the region's people, one of the largest mass migrations in world history.
As Paul Lovejoy explicitly stated in 1989: "The European slave trade across the Atlantic marked a radical break in the history of Africa, most especially because it was a major influence in transforming African society."
One of the books I have on my shelf is a collection of essays entitled *The Atlantic Slave Trade: Effects on Economies, Societies, and Peoples in Africa, the Americas, and Europe*. The first four essays in the book are devoted to the effects of the slave trade on African society. It's an older book (the essays are from a 1988 conference) but they're still reliable, I believe.
The first of the four essays, by Martin Klein, discusses the impact of the trade on the societies of the Western Sudan. He discusses how theorists believe the slave trade "contributed to a quest for arms" in western Africa. Not only did people have an economic interest to collect slaves, they also were determined to defend themselves from others who might enslave *them.* Focus on warfare encouraged famine and starvation, disrupted trade routes and led to a more impoverished life.
The constant need for more slaves meant warfare was a permanent fact of life. If you believe Clausewitz and his theory that warfare is simply an extension of politics, and that wars end when the political situation is resolved, slavery upends this theory. It creates an atmosphere and need for permanent warfare.
Sylvane Diouf, in a collection of essays called *Fighting the Slave Trade: West African Strategies* discusses how Africans attempted (sometimes successfully) to resist slavers and their lackeys. As /u/sowser [stated in a comment not too long ago](_URL_0_), "What historians find time and time again stands out in the historical record is the incredibly vibrant culture of defiance and self-determination exhibited by Africans taken into slavery, and later their descendants."
The problem is that even successful resistance takes a toll.
Slavery hugely imbalanced the population mix in western Africa. Because slavers wanted male slaves more than female ones, the slave trade encouraged polygamous relationships and discouraged monogamy -- there were many more women than men.
Slavery spread disease, as populations mixed in warfare and along the coast.
Slavery spread starvation, as slave-raiding parties burned granaries, scattered farmers and torched farms.
Slavery disrupted trade, as it crowded out the non-slave trade and discouraged conventional exchanges in things like cotton.
For all the problems slavery caused in the Americas, for all the horrors it inflicted on individuals, its effects on states and nations were just as deleterious.
***
I'd normally defer this question to /u/sowser, /u/freedmenspatrol or /u/khosikulu, but it's late and I believe they're asleep. I hope they'll come in and correct any oversights by me. | [
"Researchers estimate that between two and three million people were stolen out of this region and traded for goods like alcohol and tobacco from the Americas and textiles from Europe. Current estimates are that about 12 million Africans were shipped across the Atlantic from West Africa, although the number purchas... |
If everything in the universe doubled in size instantly
would we notice? | Yes, absolutely. In fact there are only a hand full of special systems where this wouldn't be the case for the parameters involved. We call these systems 'conformally invariant' and a side effect of that is scale invariance which is what you asking about. These systems normally involve some sort of phase transition. | [
"BULLET::::- The largest structures in the universe are larger than expected. Current cosmological models say there should be very little structure on scales larger than a few hundred million light years across, due to the expansion of the universe trumping the effect of gravity. But the Sloan Great Wall is 1.38 bi... |
what are essential tremors? what is the correlation with parkinsons disease if any? | The "essential" in the name means it's something on its own - I'm sure you've looked up the history of the term - and it's idiopathic, meaning having no known cause.
It's only related to Parkinson's in that it's sometimes mistaken for it. Also I'm not a neurologist and you should listen to yours! | [
"BULLET::::- Parkinsonian tremor is caused by damage to structures within the brain that control movement. This resting tremor, which can occur as an isolated symptom or be seen in other disorders, is often a precursor to Parkinson's disease (more than 25 percent of patients with Parkinson's disease have an associa... |
why is it so difficult to swallow when you look up, or tilt your head backwards? | Because tilting your head back opens your airway and they can't both be open at the same time. | [
"The infant's head should be slightly tilted back to make nursing and swallowing easier. When his or her head is tilted back and the mouth is open, the tongue will naturally be down in the mouth to allow the breast to go on top of it.\n",
"The tonic labyrinthine reflex is a primitive reflex found in newborn human... |
Can whales see in front of them? | They likely have a blind spot a little beyond the snout but not much further. Its not uncommon for animals to have eyes on the sides of their heads rather than the front. This is usually seen in herbivores as it gives them a almost 360 degree view (better for spotting predators).
The whale probably compensates for this blind spot (if it extended beyond his snout) by swinging his head side to side to give a more complete picture of whats in front of him.
| [
"The whale eye is relatively small for its size, yet they do retain a good degree of eyesight. As well as this, the eyes of a whale are placed on the sides of its head, so their vision consists of two fields, rather than a binocular view like humans have. When belugas surface, their lens and cornea correct the near... |
why does banana substitute the fat in baked goods successfully? | The purpose of oil is to prevent water from reacting with the gluten in the flour (which tends to make your baked goods 'chewy').
Applesauce and bananas contain something called "pectin" which can also prevent gluten from doing its thing.
The mechanisms however are different - oil works by blocking water from getting to the gluten - Pectin works by competing with the gluten, that is the pectin will react with/absorb the water before it can react with the gluten. | [
"Some varieties of banana chips can be produced using only food dehydration. Banana slices that are only dehydrated are not dark yellow and crunchy, but rather are brown, leathery and chewy. They are very sweet and have an intense banana flavor. These are ideally made from bananas that are fully ripe. Another kind ... |
How universal is the concept of religion in different cultures? | hi! It may be worth x-posting this question to a few other subs for their input: r/AskReligion, r/AskSocialScience, perhaps r/AskAnthropology | [
"The development of religion has taken different forms in different cultures. Some religions place an emphasis on belief, while others emphasize practice. Some religions focus on the subjective experience of the religious individual, while others consider the activities of the religious community to be most importa... |
why do most sinks have that "u" shape at the bottom? i've seen it in some urinals and toilets too... | Its called a trap and it prevents sewer gas from backing up the pipe into the sink or toilet/urinal. Water stays in that bend in the pipe to "trap" the gas behind it. | [
"The term \"water closet\" now often refers to a room that has both a toilet and other plumbing fixtures such as a sink or a bathtub. Plumbing manufacturers often use the term \"water closet\" to differentiate toilets from urinals. American plumbing codes refer to a toilet as a \"Water Closet\" or a \"WC\". Many Eu... |
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