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how does a country surrender? | Surrender is a conversation between the winner and the loser. Either side can theoretically start the conversation ("I want to give up!" vs. "do you want to give up yet?"). It comes down to the *terms* of surrender - the loser will often have to give up very valuable things to get the winner to stop killing them. If the loser offers to surrender first, their proposed terms may be quite lenient to themselves, but the winner can ignore them and keep fighting, or they can demand harsher terms.
Sometimes the two sides will enter a *truce* or *cease-fire*, where both sides stop fighting while their leaders negotiate. Other times negotiations will proceed while fighting is still going on.
That's for nation-to-nation surrenders. On the battlefield, surrenders are often piecemeal. A platoon or company or whatever will be completely overwhelmed, unable to fight back and unable to run away. So they drop their guns and say "we give up, don't shoot us!" They become prisoners and are led away by the enemy, while the rest of the battle may still be going on nearby. At a larger level (brigade, division, army) a surrender can be more like the nation-to-nation style of surrender. If one side has another side's army completely surrounded, they may call a cease-fire and send a messenger to discuss surrender. If the surrounded commander decides to surrender, he commands all his men to drop their guns. If not, the messenger goes back and the fighting starts back up. | [
"Surrender, in military terms, is the relinquishment of control over territory, combatants, fortifications, ships or armament to another power. A surrender may be accomplished peacefully, without fighting, or it may be the result of defeat in battle. A sovereign state may surrender following defeat in a war, usuall... |
how can doctors say someone definitively died from second-hand smoke? | Significant factor!
A doctor must complete a Death Certificate listing 1) immediate cause, 2) underlying cause(s), and 3) Significant factors contributing to death.
1) Immediate cause is almost always some series of Latin words that mean "heart stopped."
2) Underlying cause(s) is what most people think of as the "cause of death" because that will include the condition that likely brought the person to see the doctor. This could be a lot of things, but in this case probably a series of Latin words meaning heart attack, lung disease, or lung cancer.
3) Significant factors contributing to death are not the "cause" however they will often be read by the public/journalists as the thing that caused the thing that brought the person to see the doctor. If the person was a smoker, "smoking" will be listed here. If the person had lung disease but was not a smoker, the doctor will either note a known second-hand smoke source, or the CDC has some methodology to assume a certain number of non-smoker lung patients are second-hand smoke victims. | [
"The current US Surgeon General's Report concludes that there is no established risk-free level of exposure to second-hand smoke. Short exposures to second-hand smoke are believed to cause blood platelets to become stickier, damage the lining of blood vessels, decrease coronary flow velocity reserves, and reduce he... |
What was life like for the average person in Roman Britain? | The Romans were not particularly harsh rulers (in fact within that statement there are several flawed assumptions), but life certainly did not occur as usual. Britain after the conquest in 54 CE (well, really towards the end of the century) underwent a process that has been termed "Romanization". This term has been a source of considerable debate since it was coined a century ago by a man named Francis Haverfield, but at its most broad meaning it involved the material replacement of Late Pre-Roman Iron Age (LPRIA) material culture with Roman material culture. That is to say, LPRIA style housing disappeared and Roman style housing replaced it, settlement patterns switched to the Roman urban/hinterland model as opposed to the nonurnabized (or perhaps more accurately, proto-urbanized) LPRIA model, and the actual LPRIA material, like jewelry, pottery and the like, disappeared in favor of Roman style material. This is as true of the smallest rural hamlet as of the largest city.
So what happened? This is a matter of enormous theoretical debate, but it would be wise to start out with stressing what did *not* happen: large scale colonization and population transfer, There were a few colonies, but by the early Imperial period this was a matter of status rather than of reality. Being a colony granted important administrative benefits, and so Roman officials would reward communities by granting them colonial status. There were some true colonies which were started as veteran settlements (but the population was probably mostly native) but interestingly, these were not the major cities. London, the largest city, was a trading port which, granted, was heavily inhabited by foreign merchants, but the second largest city, Corinium (modern Cirencester) was native. In fact, its location was deeply situated into the LPRIA landscape, as there was a major "hillfort" located nearby. Before you assume this was a matter of control (as it technically started with a transient legionary base), it was deep in the heart of the territory of the Dobunni, a prominent Roman ally. In fact, this non colonian status also applies to the other major Roman cities, such as Verulamium and Silchester.
So what we have is *not* Romans forcibly displacing a native population, such as what occurs in the Americas, but rather something that one very influential work called "becoming Roman". There are many models of why this occurred. Perhaps the most popular one situates Roman material within the political landscape, in which elites shifted their styles of competition and display from the pre-Roman style to a Roman one, a cultural trend that percolated down to the entire population. Another model stresses the essential continuity, arguing that the British became "part of the conversation" as to the ever-difficult and multiplicitous definition of "Roman". My theory stresses the economic transformation, in which the Roman conquest brought an unimaginable change in the material opportunity of the population, which along with the stability guaranteed by the Roman legions prompted deep rooted changes in the economic strategies of the elite.
It is worth quickly making a few notes:
* Roman Britain was not rebellious, nor was it particularly difficult to hold. After Boadicea, there was no "anti-Roman" rebellion among the population, and Boadicea herself was in many ways more a tribal invader than a rebel. Britain appears to have been largely internally stable.
* This pattern mostly holds true for roughly the southern half of modern England. The norther half was sparsely populated, and Wales also remained at a low population density.
* There are many ways in which Britain retained a distinctive character, which is perhaps different than the problematic notion of "continuity". Religion largely remained distinctive, with classical-style temples very rare outside of a purely civic context. The nature of elite competition was also distinctive, with very little notion of "individual" distinction--inscriptions, or rather the few that exist, tend to represent groups as opposed to individuals. City structure was also distinctive, with large intramural open spaces.
* Cities did largely develop around military bases, but these forts should really be thought more as catalysts than the raison d'etre for urbanization. These bases rarely lasted any significant amount of time, and so the cities must be considered authentic vases of native urbanization.
* Britain was quite poor. It was probably not a giant money sink, but it was far from the enormous cities of the east or the enormously wealthy elite of Gaul. My region, roughly modern Oxfordshire and Gloucester and centered along the Cotswolds, was perhaps the wealthiest.
* There was a major shift during the third and fourth centuries, with a great deal of rural consolidation, villa expansion, and the transition from major urban centers to "villages" and "small towns". It is worth noting that in all periods of Roman Britain, the vast majority of the urban population lived in cities of roughly five thousand or less. Diet also changes towards a more "Roman" one while the province as a whole becomes less integrated with the wider Imperial economy. The exact details of this transition are complex, to say the least.
* The end of Roman Britain began in the last years of the fourth century and rapidly took place during the early fifth. The military withdrawal was no doubt related, but my model places more emphasis on the general dissolution of the Roman economy.
The best source on this process is still Martin Millet's *The Romanization of Britain*. Probably the best theoretical work on this process, only in modern France, is Greg Woolf's *Becoming Roman: The Origin of Provincial Civilization in Gaul*. JS Wacher's *Roman Britain* is still a nice introduction with significantly less theory than the other two, if somewhat out of date. In fact, JS Wacher is generally a good bet for anything.
EDIT: New note I thought of:
* The old model of Romanization interpreted it as a strategy of conquest on the part of the Roman authorities, largely based on a single passage in Tacitus and comparisons, conscious or otherwise, with the British Empire. This has largely been rejected, partially for denying British agency, and partially for many bits of evidence I can't list here now. But the one I like the most is the lack of any real administrative involvement in Britain in the form of Imperial temples, official inscriptions, and the like. | [
"\"The Little Emperors\" ends with the Roman protagonist concluding most Britons had a better life without 'Roman civilisation,' which was confirmed by a 2014 study showing average life-span actually increased in Post-Roman Britain due to better diet. Similarly, in \"Conscience of the King\" Cerdic regrets the dirt... |
How did Italian-Americans fighting for the Allies in WW2 feel about the Italy's support of the Germans? | Also on a related topic, was it common for people with Italian names to "Americanize" them? This seems to be fairly common in my area with German names. A common local example would be Young. It is common to see it on old headstones as Jung. | [
"Fascist Italy was an official enemy, and citizens of Italy were also forced away from \"strategic\" coastal areas in California. Altogether, 58,000 Italians were forced to relocate. They relocated on their own and were not put in camps. Known spokesmen for Benito Mussolini were arrested and held in prison. The res... |
Why is it, that tv shows ripped from places like Japanese television networks for example, and then uploaded to youtube, seem to almost always have a horrible resolution? | The long and short of it is that the video is likely to have been lossily transcoded many times by the time it shows up on YouTube. It's transcoded once when going from the content maker to the TV station, another time at the TV station to convert it to a format suitable for airing, possibly once more when the receiver gets the content, yet again when someone trims off all the commercials and other irrelevant bits, and finally when uploading to YouTube as well. (Some of these steps can be done losslessly, but this depends on how careful the uploader is.)
For Japanese clips in particular, the video might've also been reuploaded from Niconico Douga, which serves only low-quality streams for non-premium users. | [
"Some episodes were released on video in Japan, but a complete release of the show was held up for many years owing to poor sales. It was rumoured for that the lack of a DVD release was due to the original masters of some episodes being lost, but this proved not to be the case. Starchild Records released the comple... |
how do nfc credit cards work? do they store the credit card number? how are card numbers not stolen by people with nfc readers? | Firstly, there are no NFC cards, they are RFID. The distinction comes from power. When using NFC payment on phones, the phone transmits the signal, costing some battery life. On RFID cards, you obviously don't charge them, the card reader actually sends a tiny amount of power to them so they are able to transmit the signal back to the reader with your payment info.
On to security, these cards use something called tokenization. What this means is that instead of just transmitting your actual card number like a swipe card, they transmit a single use security code, which the card reader sends to either the processing company and/or the bank (it depends), and verifies that it is a correct security code.
Now, I am unsure if your actual card number is also sent. With Apple Pay, the iPhone sends the token and a DAN (Device Account Number), which is a verified number specific to your Apple Device (iPhone, Apple Watch, etc.) that has been verified by your bank when you set it up. I would assume when using RFID, the card also sends a DAN equivalent instead of the actual card number.
This method is the same for chip cards, except it's not wireless.
Now, where chip/RFID is less secure than Apple Pay and other NFC payments (that use a DAN), the card number is still on your card. Since swipe readers can still accept chip cards, a thief can steal your card (such as a waiter) and can copy the card number to a new card and swipe it at any reader not set up for chip (a chip card inserted to a chip-enabled reader won't allow it to be swiped).
However, the US had RFID cards about 10 years ago, but I guess they actually transmitted the actual number instead of a DAN equivalent, because you can find news stories on YouTube that show the news people going around a mall and copying people's cards wirelessly (with their consent), loading it onto a hotel room keycard, and using it at McDonalds (one that accepted contactless, so it allowed it to be swiped). I am 99% sure that they now use the current method I described with Apple Pay. | [
"In certain markets, NFC support on Windows Phone 8 can also be used to conduct in-person transactions through credit and debit cards stored on the phone through the Wallet application. Carriers may activate the NFC feature through SIM or integrated phone hardware. Orange will be first carrier to support NFC on Win... |
What can I realistically learn about history from reading Asterix and Obelix? | I'm a massive fan of the series, and grew up reading the comics in both English and French.
Historically, you're not going to learn much other than 1) The Romans conquered Gaul, 2) the Celts had Druids, and 3) Caesar had a kid with Cleopatra.
The real brilliance of the series is not in accurate presentation of historical fact but rather in its sending up of French education at the time Goscinny and Uderzo were growing up.
By Toutatis, Muskwatch, these authors are crazy!
*taps temple repeatedly* | [
"The novel revolves on a modern update of the Excalibur legend. Among the historical figures fictionalised in the novel are Chaim Weizmann, A. J. Cronin, Winston Churchill, Éamon de Valera, Anthony Eden and Joseph Stalin.\n",
"BULLET::::- First time an Asterix book makes reference to past adventures. The first in... |
How did they replace destroyed planes on WW2 aircraft carriers? | Although practice about replacement aircraft differed between navies, there were several methods for replacing damaged or lost aircraft. The most common method was to keep a number of replacement aircraft in storage on the larger fleet carriers. These aircraft were disassembled and required a number of man-hours to put back together. In the USN, starting with USS *Ranger*, carrier designs to incorporate enough space to stow aircraft in the ceiling of the hangar, as seen in this [photo from Friedman's *US Aircraft Carriers*](_URL_0_). The earlier IJN carriers tended to keep their reserve aircraft in a disassembled state in their lower hangars. The British also adapted a similiar strategy of stowing disassembled aircraft. During the war, fitters and crewmen would assemble these stowed aircraft to meet the needs of operations. For the Pearl Harbor operation, *Zuikaku*'s crew assembled its three A6Ms to act as a CAP for the fleet given the needs of the strike force had absorbed up most of the fighters of *Kido Butai*.
Yet the growing size and complexity of naval aircraft in the 1940s made this stratagem more problematic. One solution was to plan for carriers t field a larger number of fully functional aircraft that exceeded the number of pilots in their attached airgroup. Staring with *Soryu*, the Japanese planned to keep a number of excess aircraft in readiness so that they could be used as replacements in very little time. however, the persistent shortfalls of the Japanese aviation industry meant that Japanese carriers often went to sea with an understrength airwing. At Midway, *Kido Butai* parted out a number of these spare operational aircraft to other carriers, denuding the IJN's main strike force of a reserve. The USN's *Essex* class, USN fleet carriers started to field a reserve squadron of aircraft kept in near operational readiness. While the Navy Board initially envisioned a homogeneous reserve squadron, wartime experience led to a heterogeneous and truncated squadron of each aircraft type (dive/scout bomber, fighter, torpedo). Although USN investment in wing-folding technology helped ease the concerns of space, such a situation created a cramped hangar even on the the large *Essex* class ships. One solution to this problem, and one the US was able to employ because of its large industrial base, was to have a flotilla of smaller escort carriers carry reserve planes and pilots. These "jeep" carriers would supplement the aviation operations of the task force, but also serve as ferries for aircraft to either the carriers or newly captured bases in the Pacific. The British hit upon a similiar idea, but economized it with HMS *Unicorn*, which was a small fleet carrier designed to be an aviation depot ship. She had various machine shops and excess spare parts for the fleets' damaged aircraft. She carried spare aircraft and a modest complement of self-defense fighters, but was mostly designed for operation at harbors, especially those without advanced fleet facilities. She had cranes and aircraft lighters for ferrying unserviceable aircraft and her flight deck allowed repaired aircraft to take off and return to their ship.
edit: tidied up language and added a little about the wartime IJN | [
"Despite the expensive reconstructions, both vessels were considered obsolete by the eve of the Pacific War, and neither saw significant action in the early years of the war. Following the loss of most of the IJN's large aircraft carriers during the Battle of Midway in mid-1942, they were rebuilt with a flight deck... |
is it possible to remove cancer through surgery or is it only possible to remove tumors but not cancer? | Tumors are clumps of cancerous cells. "Cancer" is generally the ailment of being afflicted by cancerous cells; we can't surgically remove all "cancer" from a patient because manipulating individual cells is well beyond the capabilities of any surgeon. Conceptually they are physical objects which could be manipulated but it is beyond our practical ability at this time. | [
"Surgery with the intention of a cure is only possible in around one-fifth (20%) of new cases. Although CT scans help, in practice it can be difficult to determine whether the tumor can be fully removed (its \"resectability\"), and it may only become apparent during surgery that it is not possible to successfully r... |
why do we get "sand" in the corners of our eyes when we sleep? and why do we not get it during the day when we're awake? | The "sand" is actually dried tears.
That is, tears are similar to salt water -- liquid with salts in them. Overnight, when the tears at the edges of your eyes dry, the salt is left behind as "sand". | [
"When the individual is awake, blinking of the eyelid causes rheum to be washed away with tears via the nasolacrimal duct. The absence of this action during sleep, however, results in a small amount of dry rheum accumulating in corners of the eye, most notably in children.\n",
"The Sandman is a traditional charac... |
If an alpha particle is essentially the same as a helium nucleus (two protons, two neutrons), why doesn't a helium atom share the same ionising properties? | Alpha particles are ionizing because they have no electrons and they have high kinetic energies (alpha decay Q-values are around 5 MeV).
Bullets don't harm you when they're not shot from a gun. | [
"Alpha particles consist of two protons and two neutrons bound together into a particle identical to a helium nucleus. Alpha particle emissions are generally produced in the process of alpha decay, but may also be produced in other ways. Alpha particles are named after the first letter in the Greek alphabet, α. The... |
How likely is it that the atomic bombings of Hiroshima and Nagasaki prevented a Soviet invasion and occupation of Japan? | > Did the demonstration of atomic weapons prevent a possible occupied red Tokyo?
No. While obviously strong, the Red Army stood no chance of invading Honshu. Simply put, they didn't have the sealift capabilities to pull it off.
As the Pacific War drew to a close, the Soviets did invade the Kuril Islands. They managed to eventually land about 15000 troops there, who were faced with defeating 80000 Japanese troops. Unsurprisingly, they were having their hats handed to them when the war ended... and thus took possession of the islands.
Unlike the US, who had specialized designs specifically for troop transport and amphibious landings, the Soviet Pacific Fleet had, in comparison, nothing. They had a handful of landing craft given them by the US, but other than that they used minesweepers, destroyers, torpedo boats, and generic freighters to move their men to the Kurils. They were then unable to reinforce them with any sort of speed. It takes very little imagination to see that invasion being defeated if the war had gone on longer.
Invading Hokkaido, on the other hand, would have required many, many times more men and materiel than the Kuril invasion. And while the Red Army was a force to be reckoned with, it could not walk on water.
Heck, the US was less than sanguine about invading Tokyo. They would do so if needed, and fully expected to win, but at grievous cost... and they could move their troops in immense quantities with heavy air and sea support. | [
"Ward Wilson wrote that \"after Nagasaki was bombed only four major cities remained which could readily have been hit with atomic weapons\", and that the Japanese Supreme Council did not bother to convene after the atomic bombings because they were barely more destructive than previous bombings. He wrote that inste... |
; why do commercials say something will be aired live, but they show previews of said live event that hasn’t happened yet? | They often show rehearsals so you have an idea what it will be like, or sometimes just an earlier performance by the same artist. | [
"Another problem is that many fans prefer to record these shows and binge watch the whole season in one session. These viewers are not included in TV ratings as they are much less likely to watch commercials than live viewers. The move away from live viewing and toward DVR or internet-streaming services has hurt ma... |
what happens to valuations and stock prices in financial markets during weekends and off-hours | In most markets trading is down in those hours, so no trades are made at a different price then the market closed. However, I think buy and sell orders can be placed during off hours, influencing the price when it opens again. | [
"Time-based pricing is the standard method of pricing in the tourism industry. Higher prices are charged during the peak season, or during special-event periods. In the off-season, hotels may charge only the operating costs of the establishment, whereas investments and any profit are gained during the high season (... |
How long would it take to hard-boil an egg on Mount Everest? | The egg requires heat to be cooked, it doesn't actually boil. Boiling water is a lower temperature when it is at a lower pressure, so the egg would exist in lower temperature water, so it would cook slower or not at all depending on the pressure. | [
"Chef Heston Blumenthal, after \"relentless trials\", published a recipe for \"the perfect boiled egg\" suggesting cooking the egg in water that starts cold and covers the egg by no more than a millimeter, removing the pan from the heat as soon as the water starts to bubble. After six minutes, the egg will be ready... |
What would happen if we 'bled' a volcano? Would it release pressure, or would it make things worse? | it would completely depend on the type of volcano that you're trying to 'bleed'. If you're looking at a volcano that has a magma chamber filled with andesites and rhyolites (a very quartz rich magma) (see any of the volcanoes around the Ring of Fire") then drilling a hole to it would be pointless as these magmas have an extremely high viscosity. Not to mention that we don't have the drilling technology to even drill into material that hot. These chambers are usually under a tremendous amount of pressure, and drilling a hole in it (not that we can even drill a hole large enough to have much of an effect) would result in decompression at that point, thus consuming the drill and it's workers.
Now, if you have a basaltic chamber, such as those you find in shield volcanoes (see Hawai'i), then the product is not under so much pressure and the volcanic product has a much lower viscosity. However, these are not the types of volcanoes that cause massive destruction through exploding for just that reason. Any small crack, fault, or unused magma-tube is exploited by the very low-viscosity magma, and pressure never has time to build up.
TL;DR: no, the viscosity of the magma that produces explosive volcanoes will not respond to any kind of drilling technology we have these days.
*edit: See [here](_URL_0_) and derivative pages for an explanation of the different types of lava, their compositions, and how the chemical components alter the type of volcano and the nature of their viscosities. | [
"Gas hydrate pingo may accumulate non-hydrate gas under pressure leading to explosions that forms craters. Crater depressions of this type have been found on the seafloor of Barents Sea. A trigger for the explosions may be drop in pressure as result of lowering of the sea level.\n",
"The sudden release of pressur... |
Portuguese - Japaneese Travel routes the 1500 century | Here are some suggestions for you to look up. (I won't answer this in full, since that would mean doing your homework for you.)
Portuguese ship ca 1500-1600: I would look up Galleon or Carrack
Portuguese ships sailed down the western coast of Africa and probably stopped at Luanda, Angola to refuel. They would then round the Cape of Good Hope and sail up the eastern coast of Africa and rest at Mozambique. From there they would travel to Goa, India. From Goa they could sail to Malacca in Southeast Asia. From Malacca they could go directly to Japan or stop at Macau before going to Japan.
For the length of the journey I suggest looking at some well known journeys such as Ferdinand Magellan's and then trying to figure out on your own how long a journey actually took from point A to point B. And then making your own estimates.
For trading goods between Japan and Portugal I would research "Nanban" trade. That's the Japanese word for the Portuguese in the 16th and 17th centuries.
| [
"The Japan voyage (\"viagem do Japão\" in Portuguese) was a trade route established by the Portuguese from 1550 to 1639 linking Goa, then capital of the Portuguese India, to Japan. This lucrative annual trip was carried out under monopoly of the Portuguese crown, and was in charge of a Captain general. The charge o... |
Are there medical benefits to running the same distance faster or slower? | This is actually quite a common question. Check out some of the previous threads on this topic:
_URL_0_ | [
"The impact of long-distance running on human health is generally positive. Various organs and systems in the human body are improved: bone mineral density is increased, cholesterol is lowered. However, beyond a certain point, negative consequences might occur. Male runners who run more than 40 miles (64 kilometers... |
What are the steps between the mouth and neurons that ingested botulinum toxin takes when it causes botulism in the human body? | [Absorption](_URL_1_)
Source: [Interaction of Botulinum Toxin with the Epithelial Barrier](_URL_3_)
[Intoxication](_URL_0_)
Source: [Botulinum Neurotoxins: Biology, Pharmacology, and Toxicology](_URL_2_)
I can answer any specific questions you might have. | [
"In each of these cases, Botulinum Neurotoxin causes functional damage to SNARE proteins, which has significant physiological and medical implications. By damaging SNARE proteins, the toxin prevents synaptic vesicles from fusing to the synaptic membrane and releasing their neurotransmitters into the synaptic cleft.... |
What's the stronger protecting layer, Corning "Gorilla" glass from smartphones or sapphire crystal used in watches? Why doesn't one use the other? | They're strong in different ways. Sapphire is super-strong, but brittle. Compared to that, Gorilla glass is flexible.
For a large display that is likely to get dropped, you want flexibility. If the glass doesn't bend, it'll shatter. It's why modern phones are so much more durable than old PDAs.
On the other hand, a watch has not only a smaller surface area to worry about, but most of the impacts it will take are smaller and sharper, and sapphire is much better at resisting scratches.
There may or may not also be a difference in the way the materials interact with the capacitive touchscreen electronics. | [
"Gorilla Glass, an outgrowth of the 1960s Chemcor project, is a high-strength alkali-aluminosilicate thin sheet glass used as a protective cover glass offering scratch resistance and durability in many touchscreens. According to the book \"Steve Jobs\" by Walter Isaacson, Gorilla Glass was used in the first iPhone ... |
Is it true that Iranians knew very little about Persian and Achaemenid antiquity until European historians rediscovered it? | It depends a bit on what you mean, so the Achaemenid Persians appear in Tabari's *History of the Prophets and Kings*, the problem is that to my knowledge neither he nor any successive writer in Persian or in Arabic had access to Herodotus, which remains one of the main sources about the history of this period to this day. As far as I'm aware and based on the content of what he's writing Tabari must have been relying almost entirely on the bible, for instance. The Sassanians are better attested to and appear more reliably in the works of Tabari or Ferdowsi's *Shahnameh* (which to my knowledge does not include the Achaemenids).
As an archaeological exercise, the artifacts and antique sites like [Naqsh-e Rustam](_URL_0_) were not systematically excavated and analyzed until European historians began to do so in the 19th and 20th centuries, as was equally true, say, of archaeology in Egypt or Turkey or Iraq and so on. | [
"The oldest date of use of Old Persian as a spoken language is not precisely known. According to certain historical assumptions about the early history and origin of ancient Persians in southwestern Iran (where Achaemenids hailed from), Old Persian was originally spoken by a tribe called \"Parsuwash\", who arrived ... |
Why do microwaves damage circuitry? | Microwaves, or any light for that matter, are oscillating EM fields. In the case of MW its on the same size order of most of these objects so the fields couple very well.
These fields then induce a current which then proceeds to short or melt various parts of circuits. | [
"The continuing trend towards reduced feature size and voltage in integrated circuits renders modern electronics highly susceptible to damages caused by High Power Microwave (HPM) and other microwave based directed energy sources. These induce high voltage transient surges of thousands of volts which can punch thro... |
why are not all electromagnetic waves visible to the human eye? | The EM receptors that evolved on Earth are able to see a part of the EM spectrum on Earth. Some creatures have more or less receptors and can see more/less than humans but this is a common theme with evolved traits. Either a mutation to see more never occurred or it did occur but wasn't useful enough to spread through the entire population. | [
"Refraction not only affects visible light rays, but all electromagnetic radiation, although in varying degrees. For example, in the visible spectrum, blue is more affected than red. This may cause astronomical objects to appear dispersed into a spectrum in high-resolution images.\n",
"Visible light can be seen b... |
how is digital music (such as techno, electro, etc.) made? what makes up the sounds that they use? | So, you have to start by remembering that all sound is just a vibration. Musical instruments get their sound by having a vibrating piece, like a reed, or a string, or the musician's lips, and then funnel that vibration through the instrument to refine the sound. The way the instrument sounds is caused by the fact that this process produces not just one vibration, but a complex set of them. Your ears sort of collapse all of what are called the overtones into just one note, but the different overtones cause you to perceive the different sounds of each instrument, even when they're playing the same note.
So, thought some scientists, what if we made our own instruments from the ground up? And they came up with the synthesizer. The synthesizer produces sounds by creating vibrations that are tailored by the person making the music. The first ones used basic sounds that you may recognize from early video game music or chiptunes.
* Sine wave- follows the same pattern as the graph of y=sin(x). The vibration's waveform (the shape of the sound wave) looks like [this](_URL_3_) and the note sounds like [this](_URL_0_)
* Square wave- Similar in shape to the sine wave, but instead of rising and falling smoothly, it jumps almost instantly between the maximum, minimum, and zero values. The waveform and sound are both available in [this video](_URL_4_).
* Triangle wave- This one goes up and down at a rate that forms a straight line. You can see and hear this wave [here](_URL_2_).
* Sawtooth wave- This one runs smoothly up to the maximum value, then drops immediately to the minimum and repeats. You can see and hear this wave [here](_URL_1_).
Now, if you paid close attention to those last videos, you'll notice the wave changed as he changed the pitch. The shorter the wavelength (the distance between peaks of the wave), the higher the pitch sounded. The longer it was, the lower the pitch. Similarly, the amplitude (how high the maximum and how low the minimum are) controls volume- larger amplitude means louder sound.
Now, once these building blocks were in place, more tools followed. The synths I showed above will produce music, but it's kind of robotic. This is because instruments produce sound that change their waveforms over time. So, one of the basic ways to mimic this is the ASDR sound envelope. This stands for the following:
* Attack- how does the sound behave when the note begins? Does it strike hard? Does it fade in gently?
* Decay- What happens after the attack? Does it hold steady? Does it drop down so the attack is louder than the note?
* Sustain- how does the sound behave while the sound is held? Does it get louder? Does the pitch wobble to create vibrato? Does the volume change frequently to make a pulsing sound?
* Release- how does the sound behave when it ends? Is it a clipped ending? A gradual fade?
So now you cans tart with a number of waveforms which have different sounds, and you can modify them to get different-sounding notes. From there it's just a matter of adding more and more tools that allow the artist to edit the waveform of the synthesizer without having to manually go in and mess with the curve of the waveform (although some people do that, too!) Once you have the synthesizer sounding the way you want it, the rest is just like composing any other music.
Special note on drum sounds:
There are two types of drum sounds you often find in electronic music. One of them is just a low, rounded note, much like the sound of the timpani or the bass drum. The other is based on noise (the static from a TV is 'white noise', one type of the noise we're talking about here). The reason noise works as a basis for s drum sound is that drums don't have nice, clean harmonics- the different vibrations they produce don't stack up neatly the way other instruments' do. Instead, they produce a chaotic assortment of vibrations that our hearing can't resolve into one note, giving them the characteristic 'bang' sound. Noise works well as a starting point for things like a snare drum effect because it, too, is a chaotic mixture of vibrations. There are many tools that can be used to refine the noise into the particular sound desired, as with other synths.
In addition to this, of course, you can also use 'samples' which is just a term meaning you can include other recording - spoken words, bits of another song, vocal snippets, and arrange them to play in a rhythm just lie arranging notes in any other piece of music. You can also create samples synths, where a 'real' instrument is recorded and then that sound is pitch-shifted and/or set to a rhythm instead of building the sound from scratch.
| [
"Electronic or digital music technology is any device, such as a computer, an electronic effects unit or software, that is used by a musician or composer to help make or perform music. The term usually refers to the use of electronic devices, computer hardware and computer software that is used in the performance, ... |
i suck at math, why is this comic funny? alternatively, if it's not funny, what the hell does it mean? | The first line is [Euler's identity](_URL_1_). It's a formula that involves the numbers e, pi, and the imaginary number i (the square root of 1).
From there the artist butchers the math, replacing "Pi" with "P x i" (in math, the multiplication symbol can often be often omitted, so Pi is like P x i).
From there the calculation is legitimate (for example i x i = -1, since i is the square root of 1), resulting in P = 0.
[P = NP](_URL_0_) is an unsolved problem in computational theory, which has nothing to do with e or pi. The terms P and NP are just short for "Polynomial" and "Nondeterministic Polynomial". However the artist treat it as an actual equation: P equals N times P. Since he has "proven" that P = 0, this means that P = NP (since anything times 0 is 0). | [
"We write jokes, and the jokes are funny. With a game, the fourth, fifth, sixth, 80th, 100 millionth time you've seen that joke it becomes not funny, then you lose faith in it, and then you question it, and you go round this emotional circle ... We've always liked fresh-baked stuff a little better but, with a video... |
why couldn't the eagles have taken bilbo and the dwarves/the fellowship to the lonely mountain/mount doom? | I've been a Tolkien geek for 27 years ... I think I can shed some light on this for you.
Gandalf, Saruman, and Radagast are called "wizards" but they are actually beings called Maiar. There are tons of them, but Gandalf, Saruman, and Radagast (and two other not mentioned) are part of the Istari sent by Illuvatar (god) to aid the elves and men in their struggle against Sauron (a corrupted Maiar). They are forbidden from directly getting involved, they can only help the elves and men defeat Sauron. If not for this, the 5 Maiar that make up the Istari could have beaten Sauron together without elves and men ever having to lift a finger.
The Eagles are also Maiar (hinted at by Tolkien himself in an interview, but never directly stated) that have taken animal form rather than human form. While never directly stated, it is easy to imagine that the Eagles are simply not permitted to give that level of aid, just as the Istari were not permitted. In addition (and this IS directly stated) the Eagles do not much care for elves, dwarves, and men ... and may very well just not care. Picking up Frodo was simply just a favor for Gandalf.
Lastly ... the point of sending the Fellowship, is that on foot, they could avoid the Eye Of Sauron ... if the Eagles were sent, the Eye would be directly on them. Mordor has the 'Fell Beasts' which would be a formidable match for the Eagles. The Eagles would likely triumph against Fell Beasts, but if even just a small slip up happened (like dropping it while being attacked) it would give the ring right back to Sauron making the war virtually unwinnable. Sauron would likely have also arranged for any access to the fires of Mt Doom require entrance indoors where they would be no match for Sauron himself.
A stealth mission on foot was really the only option.
--------------------------------------------------------------------------------
Quote from Tolkien himself:
"The Eagles are a dangerous 'machine'. I have used them sparingly, and that is the absolute limit of their credibility and usefulness."
The Letters of J.R.R. Tolkien, No 210
--------------------------------------------------------------------------------
For more on this subject, see link below:
_URL_0_
| [
"The idea of the Eagles transporting the Ring to Mount Doom, or at least part of the way, is not discussed in \"The Lord of the Rings\" and Tolkien himself apparently never specifically addressed it, except in an oblique manner. In \"The Letters of J. R. R. Tolkien\", he stated: \"The Eagles are a dangerous 'machin... |
hot tea tastes wonderful! iced tea is yummy. why does hot tea that's gone cold taste horrific? | Iced Tea tends to have a buttload of sugar in it, more than you would put in hot tea, which offsets the bitterness of hot-tea-gone-cold | [
"In restaurants, iced tea is usually served unsweetened except in the Southeastern United States where iced tea is much more common and is available both sweet and unsweetened and \"iced tea\" is often considered to be \"sweet tea\" unless otherwise specified. The reason for the presweetening is that it may be diff... |
Hopi and Aztec religions have a lot in common, minus sacrifices. Were any of the Southwestern nations in contact with Mesoamerica? | In regards to the "prophesied the arrival of a white man" statement, perhaps these two previous topics from our [FAQ section on Mesoamerica](_URL_0_) are of interest.
* [Did Moctezuma II really believe Cortes was 'an armor-clad God'?](_URL_2_) by /u/Ucumu and /u/400-Rabbits
* [I've heard that Cortés arrived in America on the same year that an Aztec prophecy predicted a god was supposed to come to earth. Is this true?](_URL_3_) by /u/military_history
In regards to your question specifically, perhaps the section [Pre-Columbian Trade and Contact](_URL_1_) will answer your inquiry.
I will comment and say that direct and sustained contact between the Southwest and Mesoamerica was probably fleeting. There are points in history in which contact and trade is much greater than at other points. For example, in the Epiclassic (~550 - 900 AD) in West Mexico, the Aztatlan culture were heavily involved in trade to the Southwest. Being a coastal culture, they produced a lot of cotton and textiles which were presumably traded northward. Along with the textiles, the Aztatlan culture may have also introduced bronze bells to Southwestern peoples. However, the Aztatlan culture is not the only culture to make contact and trade. In the Postclassic, for example, turquoise was traded from the Southwest to Central Mexico. In return, Southwestern peoples may have received cacao. Scarlet macaws are another item traded to the Southwest. These macaws, however, are only found on the Gulf Coast around Veracruz and San Luis Potosi and southward. There is evidence that macaws were not only traded to the Southwest, but were also raised by Southwestern peoples. This would necessitate people having to cross a desert to bring live macaws to the Southwest from the Gulf.
The reality is that there is no one route that any sort of trade and contact took place between the Southwest and Mesoamerica. Different peoples traded different things at different times. The larger question is whether you had people walking from the Basin of Mexico to modern-day Phoenix or if these goods exchanged many hands through a series of intermediaries who occupied marginal and difficult environmental conditions. | [
"Aztec religion is one of the most widely documented pre-Hispanic cultures. Diego Durán in the \"Book of the Gods and Rites\" wrote about the religious practices devoted to the water gods, Tlaloc and Chalchiuhtlicue, and a very important part of their annual ritual included the sacrifice of infants and young childr... |
Is there any way for low frequencies of light to constructively interfere to form a higher frequency with minimal energy lost? | You can frequency double light inside a non-linear crystal. If you put this crystal into a cavity - so more or less two mirrors opposite to each other - then you can get conversion efficiencies of up to 90%. This process does not require external energy except for the light you double in frequency, since the conversion itself is energy conserving.
The underlying process for the frequency doubling is the non-linear response of the polarization in a medium: If you sent light in a dielectric medium, then dipoles will start to swing back and forth because of the electric field component of the light. For very high intensities they will no longer swing at the same frequency as the incoming light. Accelerated charges that swing at a certain frequency will produce light of this frequency. If you get the geometry just right the contributions from dipoles at different positions in the crystal add up and you get measurable intensities at these higher frequencies. With the cavity you make sure that your light at the initial frequency passes through crystal several times, which will increase the conversion efficiency.
If you ever got hand onto a green laser pointer - they usually work like that. The green light is produced by frequency doubling near infrared light. | [
"At high frequencies, particularly radio frequencies (RF), inductors have higher resistance and other losses. In addition to causing power loss, in resonant circuits this can reduce the Q factor of the circuit, broadening the bandwidth. In RF inductors, which are mostly air core types, specialized construction tech... |
Is it bad to take medication you don't really need? | Yes, because you will experience the adverse effects of that medication. Whether or not these adverse effects have any long-term impact on your life is another question and depends on the medication and chance. You may experience no adverse effect, or you may experience a really rare adverse effect that has crazy negative consequences.
For example, for isotretinoin (accutane), there are some very unpleasant and very rare side effects like diabetes, convulsions, etc. | [
"When people fail to take their antidepressants, there is a greater risk that the drug won't help, that symptoms get worse, that they miss work or are less productive at work, and that the person may be hospitalized. This also increases costs for caring for them.\n",
"Individuals who are on prescription medicatio... |
how can we not feel any of our inner organs? or better why do we only feel pain and no other feeling with them? | Because you don't really need to.
Actually, you can kinda feel your organs. You can have sensations of pressure or distension in your stomach and bowels. If you take a deep enough breath, you can feel some shifting of your internal organs, or viscera.
But you're right that, for the most part, proprioception of your internal organs is largely restricted to pain. The reason for that is because the only time you'd ever really need to know anything about your internal organs is when they feel pain. Pain is a sign of something is wrong, usually the first and most urgent and most characteristic. You don't need to know the exact size and position of your stomach at all times of the day like you would with, say, your arm, which you rely on to interact with the outside world. You don't need to know which lobes of your liver are currently working the hardest; that's just taking up space in your conscious mind and it's not information you can really do anything with. Visceral sensation is only valuable when there's something wrong with the actual viscera. Otherwise, if all systems are working fine, why clog the bandwidth? | [
"There are two main types of pain that we experience in our bodies: pain caused by damage of body tissue and pain caused by nerve damage. Nociceptive pain serves as a warning or signal for tissue damage and works to preserve the body’s equilibrium and functionality. This pain is signaled by the interworkings of bot... |
do dogs recognize their own barks? | Well, most of the time people aren't sure of their own voice with a recording... so the same probably applies to dogs. | [
"These dogs are outstanding bay dogs, or tracking and hunting dogs. They have been known to track animals from miles away, and have been used for hunting feral pigs, squirrel, deer, raccoon, mountain lion, and black bear. They often track silently and only begin to make their distinctive baying bark, eye to eye wit... |
why do we have the capacity to hate ourselves? | Free thought and free will has many positives and negatives. Increased intelligence means that we also can see the uglier sides of things, and well.... | [
"Nate Leipciger: “You cannot have hate in your heart without being hateful against yourself. And that’s the big problem – when you are hateful, you become bitter, you resent everything and that becomes part of your nature.” Student: “You don’t hate the soldiers, who took those kids out [and murdered them]?” Nate Le... |
how to understand and to visualize the 4th to 10th dimensions | There is no easy way to visualize it but this video does a good job!
_URL_0_
Edit:
Just found a way toi visualize the 4
A point has 0 dimensions.
A line segment is a 1 dimensional object bounded by 2 0-dimensional points.
A square is a 2 dimensional object bounded by 4 1 dimensional lines.
A cube is a 3 dimensional object bounded by 6 2,dimensional squares.
So, a 4-dimensional version would be bounded by 8 3-dimensional cubes as its sides. | [
"Dimensions are the variables of the data and can be mapped to specific locations in space; 2D data can be given 3D volume by adding a value to the \"x\", \"y\", or \"z\" plane. \"Assigning height to 2D regions of a topographic map\" associating every 2D location with a height/elevation value creates a 2.5D project... |
what are arrays in programming? | You know what a variable is, yes? x = "fred". Simple.
Now, imagine you have a set of 500 words, and you want to store each of them in a separate variable. Sure, you could do:
x1 = "once"
x2 = "upon"
y = "a"
z = "time"
and so on, but it would be a problem. First, it would take ages to write the code. Secondly, if you wanted to step through each of those 500 variables, to process each one in turn, it would be really difficult.
So an array is a variable which can be split into compartments. You might have an array called x, and then do:
x\[1\] = "once"
x\[2\] = "upon"
x\[3\] = "a"
x\[4\] = "time"
and so on. Now, if you want to print out the contents of the array, you don't need to know which 500 variable names you chose, because it's all x. You just set up a loop like:
for (count = 1 to 4)
{
echo x\[count\]
}
Here, x is a one-dimensional array. Like a row of cells on a spreadsheet. You can have 2-dimensional arrays too, like a grid:
x\[1,0\] = "once"
x\[1,1\] = "upon"
x\[1,2\] = "a"
x\[1,3\] = "time"
x\[2,0\] = "lived"
x\[2,1\] = "happily"
x\[2,2\] = "ever"
x\[2,3\] = "after
Then you'd use 2 loops, to step through each value of each dimension in turn. | [
"An Array is a JavaScript object prototyped from the Array constructor specifically designed to store data values indexed by integer keys. Arrays, unlike the basic Object type, are prototyped with methods and properties to aid the programmer in routine tasks (for example, join, slice, and push).\n",
"Arrays: are ... |
Why do all objects in space seem to be moving very fast? | Let me flip it around: why does everything on Earth seem to be moving so slow? Massive particles can have any velocity between 0 and 299,792,458 m/s, but on Earth everything seems to be going only a few hundred meters per second or (usually) much less. Well, because atmospheric drag keeps most things below the speed of sound, and friction with the earth and with water tends to keep things even slower.
Also important to note that velocity is entirely relative, so this question is really about why things tend to have a high velocity relative to the Earth.
The escape velocity from our Galaxy is several hundred km/s, so we don't expect to encounter a lot of things moving faster than that within the galaxy. Escape velocity from the Sun is about ~70 km/s at Mercury's orbital distance, and decreases as you go outward. So we don't expect to see many objects in the Solar System moving at more than ~10^2 km/s.
As to why things have "high" velocity relative to us, consider what happens if they don't. If something has a very low velocity relative to Earth, it will fall to Earth. Just to stay in low Earth orbit requires you to move at around 7 or 8 km/s. That's why we don't see things with very low velocities relative to Earth, except for objects in the [Lagrange points](_URL_0_), where the Earth-Sun system creates points where objects will orbit synchronously with the Earth. | [
"An object moving in a circular motion—such as a satellite orbiting the Earth—is accelerating due to the change of direction of motion, although its speed may be constant. In this case it is said to be undergoing \"centripetal\" (directed towards the center) acceleration.\n",
"This is known as \"uniform motion\".... |
why do humans tend to seek for competition, success and out doing others? | From evolutionary standpoint: To find better mate and reproduce. But the humans are capable of overcoming such base motivations. | [
"In \"Things Hidden Since the Foundation of the World\" (1978), René Girard posits that human behavior is based upon mimesis, and that imitation can engender pointless conflict. Girard notes the productive potential of competition: \"It is because of this unprecedented capacity to promote competition within limits ... |
Trying to remember the name/location of an ancient battle | You're thinking of the Battle of Ilipa in the Second Punic War, in which Hasdrubal Gisco was the Carthaginian commander, while Scipio Africanus led the Romans. In the leadup to the battle, Scipio would array his heavy Roman troops in the center, with the more lightly armed Iberian allies on the wings. Hasdrubal matched this setup: heavy center, light wings. On the day of battle, Scipio switched it up, deploying his heavy troops to face Hasdrubal's light troops. Sun Tzu would describe it as hurling a stone against eggs. With the flanks sundered, the Carthaginians were routed and cut down. | [
"The locations of ancient battles can be apocryphal. In England, this information has been more reliably recorded since the time of the Norman conquest. Battles are usually named after some feature of the battlefield geography, such as the name of a town, forest or river, commonly prefixed \"Battle of...\", but the... |
What do we know about Native American cuisine? | I have answered a number of questions on Native American, specifically Mesoamerican, cuisine that you may find informative. Please feel free to ask any follow-up questions.
_URL_1_
_URL_4_
_URL_5_
_URL_6_
_URL_3_
_URL_2_
_URL_0_ | [
"Information about Native American cuisine comes from a great variety of sources. Modern-day Native peoples retain a rich body of traditional foods, some of which have become iconic of present-day Native American social gatherings (for example, frybread). Foods like cornbread are known to have been adopted into the... |
Prior to the Emancipation Proclamation, when property in Confederate territory was confiscated by the Union what became of slaves which were legally part of confiscated estates? | Good question. Lincoln was very keen to dampen, not fan, the flames of war during the early years of the Civil War for a couple of reasons. First, border states like Kentucky were still on the fence about whether or not they were going to secede. Lincoln didn't want to give them a push one way or another by acting like the rabid abolitionist the Southern (and Democratic) press made him out to be. Until the Emancipation Proclamation, Lincoln's policy on slavery was very tame compared to what he endorsed after 1862. If Lincoln's administration confiscated slaves and "freed" them by way of not returning them to their masters, Lincoln threatened this tenuous neutrality in the border states. Second, early in the war, before anyone really understood how protracted a conflict it would be, Lincoln was keen to not antagonize the Southern people any more than he had to. Lincoln believed (hoped?) that the war would be over within a year or so, and didn't want to fan the flames of discontent that had, in-part at least, started the war. Thus, the policy in the early days of the war was for Northern (Union) troops to return slaves to their southern masters if a dispute came up. Gen. Benjamin Butler changed all of this when he (all on his own) decided that slaves were contraband of war, and therefore liable for confiscation by the Union forces. Butler was quietly scolded for taking such a sensitive issue head-on without first getting approval from the White House, but his policy largely stood (on an informal basis, anyway) until 1862, when Butler's contraband policy became the de facto policy of the Union forces. The reasoning behind it was that slaves were contributing to the Confederate war effort, and therefore were liable for confiscation by the Union. | [
"In August, the US Congress passed the Confiscation Act of 1861, which declared that any property used by the Confederate military, including slaves, could be confiscated by Union forces. The next March, its Act Prohibiting the Return of Slaves forbade returning slaves to Confederate masters or the military.\n",
... |
how the us supreme court decided the 2000 presidential election, and how is the decision viewed today? | With all states except Florida counted, neither candidate had the majority of 270 electoral votes they needed to win. The 25 electoral votes from Florida would give either candidate the Presidency.
The Florida vote was extremely close. There was a long process of a hand count which ended with Bush leading by less than 1000 votes.
Gore requested recounts in only heavily Democratic districts. The U.S. Supreme Court ruled that that approach was unconstitutional because it did not treat all ballots in the state equally, especially with different criteria being used to recount in each county.
Probably the most controversial part was that the U.S. Supreme Court also ruled that there was not enough time remaining before the legal deadline to conduct a full state recount. This basically ended all legal challenges and with Bush in the lead, he was the winner. The ruling had a 5-4 split.
If the selective recount Gore requested would have happened, Bush still would have won.
If a state-wide recount would have happened, using the standards the election officials stated they would have used, Bush would have won.
If a state-wide recount would have happened, using some other theoretical standards, Gore would have won.
| [
"After winning the presidential election, Trump and White House Counsel Don McGahn interviewed four individuals for the Supreme Court opening, all of whom had appeared on one of the two previously-released lists. The four individuals were federal appellate judges Tom Hardiman, Bill Pryor, and Neil Gorsuch, as well ... |
Found brittle WW2 newspapers, Need suggestions re: preservation | So first off you actually want to maintain a dry environment (35%) humidity or less for the paper. Paper in a Humid environment may actually disintegrate faster.
It's important that you try not to touch the paper with your bare hands the oil on your fingers can actually cause further break down.
Here are some great resources for saving and preserving documents.
1-_URL_2_
2-_URL_3_
3- (On storing documents) _URL_3_images/stories/documentsarchives.pdf
4- (On mounting and framing) _URL_1_
5- More on preserving and mounting _URL_0_
6- _URL_4_
Hope this info helps you!!
| [
"In May 1988, a library in New Haven, Connecticut decided to take all of their materials that were getting really old, brittle, falling apart of even deteriorating like books, maps, manuscripts and other materials to be transferred to microfilm, so that the materials could be saved.\n",
"The library was nearly co... |
What capital cities have never been sacked or conquered? | Sorry, this question has been removed for being a [throughout your era question, which the rules don't allow](_URL_0_). | [
"Because of its wealth and its strategic location near the coast, the city was sacked several times during and after the fall of the Roman Empire, by Goths, Vandals and, finally, by the Saracens who destroyed it in 827. The inhabitants subsequently moved to the ancient acropolis and founded a new community.\n",
"... |
what even is a permanent record? | Student records commonly include details such as class grades, important test scores, attendance records, health and immunization information, discipline records, special awards conferred, previous schools attended, and so on. In other words, these 'permanent records' are typically just a log of various information that is unique to each student. | [
"Long-term records are those that are identified to have a continuing value to an organization. Based on the period assigned in the retention schedule, these may be held for periods of 25 years or longer, or may even be assigned a retention period of \"indefinite\" or \"permanent\". The term \"permanent\" is used m... |
What properties of beet juice make it a useful additive for combating snowy/icey roads? | I'm not 100% sure but:
Trimethylglycine found in the byproduct produced in the processing of sugar beets. Trimethylglycine is a freezing point depressant, similar to salt, and has applications in prevention of freezing of aircrafts and runways.
In addition to the freezing point depressant properties, trimethylglycine is also sticky, meaning it doesn't run off due to water as much as salt does.
These two things may result in it being suitable for deicing roads.
I imagine they don't use pure beet juice because it's much more expensive than salt would be. | [
"When beet juice is used, it is most stable in foods with a low water content, such as frozen novelties and fruit fillings. Betanins, obtained from the roots, are used industrially as red food colourants, e.g. to intensify the colour of tomato paste, sauces, desserts, jams and jellies, ice cream, sweets, and breakf... |
in ocean searches for lost ships / planes, who pays the private companies for their time and resources? | I am assuming there is a some kind of compensation if something is found, but I think it is mostly PR. Take a merchant ship that isn't needed in port urgently who happens to pass through the search zone. Go ahead and "Look for remains" while just continuing its rout with some guys on double shifts checking out the ocean. | [
"Investment in ships involves purchasing or leasing new or second-hand vessels and either operating them directly or chartering them to other operators. Investors seek either profits generated from shipping fees, capital appreciation of the vessels themselves, or both. Due to the high capital commitments involved, ... |
Is it possible to be immune to certain drugs? | In addition to what the other poster wrote, there are cases where a person is a hypermetaboliser of certain drugs, to the point that normal dosage may be ineffective. Sometimes a larger dose can be given to overcome the problem but it may still be short acting and largely ineffective, and if the metabolites of the drug may be toxic then organ damage is a possibility, or more acute sickness.
It's also possible to metabolise drugs at a very low rate, which is a different issue.
In the case of building up to "immunity" the term used is tolerance. Generally the receptor for the drug is made and expressed on the outside of cells less. When there's fewer receptors less of a response can be caused. This can mean a response to a drug is minimal.
The only other reason I can think that a drug might not cause a response is if the drug target is mutated or not expressed in an individual. Purely hypothetically, because I can't think of a real-life example, if an antibody was created specific only to T. gondii infected cells, there should be no response if the antibody is given to someone not infected with the parasite (this is a bad example for a few reasons but off the top of my head and for a simplified example it'll do). | [
"The proposed mechanism of most idiosyncratic drug reactions is immune-mediated toxicity. To create an immune response, a foreign molecule must be present that antibodies can bind to (i.e. the antigen) and cellular damage must exist. Very often, drugs will not be immunogenic because they are too small to induce imm... |
How were deserters from the U.S. army punished during/shortly after the revolution? | Deserters from the Virginia militias faced the "general discretion of the court martial" for the first two years of the Revolution and then a fine not more than two month's pays or imprisonment of not more than one month. In the fall of 1777, additional months of service was the most common form of punishment. A bounty was also placed on deserters (of varying amounts, thanks to inflation).
Broadly speaking, Virginia used both the carrot and the stick, proclaiming an amnesty in 1780 for deserters who returned to the fold, but also threatening a punishment of five years of service for those who did not. The reality of the situation was that the desertion rate was so high that, as a general rule, the punishment could not be exceedingly harsh in practice and the ever-increasing fines and punishments associated with desertion reflect not the hardened resolve of the Commonwealth cracking down, but rather it's powerlessness in the face of a problem it cannot solve. | [
"In the United States, before the Civil War, deserters from the Army were flogged; after 1861, tattoos or branding were also used. The maximum U.S. penalty for desertion in wartime remains death, although this punishment was last applied to Eddie Slovik in 1945. No U.S. serviceman has received more than 24 months i... |
Science: How close are we to curing HIV/AIDS? | A bone-marrow transplant from someone immune to AIDs can cure you. It's horrible painful and a tad expensive, and requires you finding someone immune, but it's possible. | [
"Professor Barré-Sinoussi believes that scientists have made steady progress given the development of antiretroviral treatment which UNAIDS states is being accessed by 17 million of the people globally who are living with AIDS, but finding a cure, or cures, will take time, and a continued investment in research. As... |
how the double-heading (double engine/locomotives) railways work efficiently ? | Multiple-unit train control - basically single control for all the engines running one train have been around in different forms from 1920's | [
"Most modern diesel and electric locomotives can run equally well in either direction, and many are push-pull trains with control cabs at each end. In addition, railroads often use multiple locomotives to pull trains, and even with locomotives that have distinct front and rear ends, the engines at opposing ends of ... |
What are some examples of beneficial microorganisms? | Microbiologist here. Microorganisms are unbelievably important for human and environmental health, and without them, life as we know it wouldn't exist. Some examples to answer your question:
*E. coli* is used to produce synthetic insulin (_URL_2_)
*S. cerevisiae* is the yeast (a type of fungus) responsible for making all alcoholic beverages, and has been invaluable for biological research
Bacteria in the soil such as those in the genii *Nitrobacter*, *Nitrosomonas*, and *Nitrosoccoccus* are responsible for converting the nitrogen in the air into nitrogen that can be used by living creatures. Nitrogen-oxidizing bacteria are also used in wastewater treatment plants to (_URL_4_)
Speaking of which, microbes are invaluable to wastewater treatment plants (_URL_3_)
*cyanobacteria* are nitrogen fixers and also produce oxygen as a waste product. The oxygen that we breathe today was originally produced by microbes in this phylum billions of years ago. (_URL_5_)
Microbes in the human gut are important for the development of the immune system, metabolism, and synthesis of vital nutrients. (_URL_7_, _URL_0_, _URL_1_, _URL_6_)
A short (albeit unusual) video about the importance of the microbes for human health may be found here: _URL_8_
| [
"Microorganisms are useful in producing foods, treating waste water, creating biofuels and a wide range of chemicals and enzymes. They are invaluable in research as model organisms. They have been weaponised and sometimes used in warfare and bioterrorism. They are vital to agriculture through their roles in maintai... |
What is the correct way for loading a Napoleonic muzzle-loading flintlock musket or rifle? | First of all, I'd like to state that while I Have read many of Cornwell's Sharpe books, I do not have any copies at hand, so I can't directly reference the details of loading, per Cornwell's descriptions and how accurate they are, so I'll speak generally to the process, and the possible source of the inconsistency you've noted.
As for the loading process, the manual of arms between the advent of firelocks from the late 17th century through to the late 19th century remained, essentially, unchanged. There were usually ten distinct steps, with several manuals, both American, British, and Continental different primarily in how each step was broken down.
According to the 1815 Manual of Arms (Section 29: Platoon Exercise, pp 27-29) there are 11 actions to be conducted. I should note that the 1815 Manual of Arms is a revision of an 1807 Manual, which in turn was a revision of an 1801 manual. It is from the 1815 Manual I'll be detailing the processes, however I've also listed a few other manuals (namely the 1764 British manual, as well as several American ones) for you to cross-reference.
In British line combat, the first command given upon firing is the order to "Load!" At this point, it is an order for the unit to shift stances. The firing stance involves the instep of the right foot being posted at a 90 degree angle from the left heel at about a half step back.
When the Load order is given, the feet return to a resting position from the firing stance, and also announce that the loading drill will now be conducted.
The next order to come is "Handle Cartridge". The gun, now supported by the left hand, is balanced between the upper arm and torso of the right arm, the butt seated firmly as the gun is balanced and suported by the left. The arm remains stiff and serves as a balance while a cartridge is withdrawn from the cartridge pouch, usually laid slightly right of centered upon the right buttock. With just thumb and forefinger, the snap on the box is removed, and the leather lid lifted, a cartridge removed. Palming the cartridge, thumb and forefinger are again used to snap the cartridge box once again, securing it. The second stage of the order involves the movement of the paper cartridge to the mouth. The cartridge, held in thumb and forefinger, is bitten by the paper tongue.
That position is maintained until the order "Prime!" is given. Then, gently, thumb (capped over the tear, to prevent the loss of powder from the hole) and forefinger are squeezed at the torn cartridge top. It is then tipped into the pan, a small pinch of powder deposited. As the cartridge is lifted from the pan, the wrist turns, three fingers closing the pan in the process. This secures the pan and the priming powder, to allow for the loading of the barrel.
Later Manuals will ordain that the firearm is rested by the butt upon the toe of the right foot or upon the ground. However, the 1815 manual suggests that the firelock is maintained at a height of two inches, held in the left hand when the order "Cast About!" is given. The muzzle of the firearm should be level with the breast. The firelock is turned such that the lock is pointed away from the loader's body. That is, the trigger guard of the musket was pointing towards the loader. The left hand now grips the barrel and stock at the same point as ever. At this stage, the cartridge has been seated into the barrel. The firelock is the dropped those two inches to the ground between the feet. This shakes the powder out of the cartridges into the barrel. The paper cartridge itself, as well as the ball, are not yet loaded. The cartridge thus seated, thumb and forefinger grab the ramrod by the head.
Ramrods are then drawn with the order "Draw Ramrods!" as the rod is lifted most of the way out of the barrel. The soldier grabs the rod midway along the length, gripping the ramrod backhandedly - that is, wrist turned, thumb pointing downward, as though giving a "thumbs down". Once fully extracted, the wrist is rotated and the ramrod put one inch down the barrel. This pushes the paper cartridge and ball down the barrel, but does not fully seat it. That will occur in the following action.
"Ram Down Cartridge" was the ninth command. The ramrod is then pushed down the barrel, forcing it down. The ramrod is continuously forced down the barrel. As it slides, the soldier adjusts his grip again to grab the ramrod by the end now protruding from the barrel. Once properly seated, the cartridge is given two firm taps and the ramrod remains at the base. Thumb and forefinger remain on the ramrod tip. The hand then palms with the remaining fingers the mouth of the barrel.
The tenth order barked "Return Ramrods!" involves the retrieval of the rammer. In as few motions as possible, the soldier grabs the ramrod and thrust it upward to retrieve it from the barrel. He then grips the rod by the midway point of its length, backhanded in the same way he gripped the ramrod while drawing the rammer. The ramrod is then lifted from the barrel entirely, the hand returned to the normal forehand positioning while still gripping the ramrod. The ramrod is then returned to the sleeve beneath the barrel. Once the ramrod is replaced, the firelock is lifted from the ground and the weapon is pivoted so that the top of the firelock now faces the soldier.
At this point, the weapon is loaded. The only thing remains is to "Shoulder Arms!" by ensuring ramrod and bayonet are fixed securely in their proper places with a "strike" by the right hand at the muzzle of the musket. Once secure, and in the same motion, the right foot comes from its perpendicular position. As the right foot comes into the position of Attention, that is 45 degrees with left and right heels touching, the firelock is shouldered in a single fluid motion, the toe of the right foot being used to nudge the butt of the firelock to initiate the smooth movement of the weapon.
From here, soldiers await the firing drill. When it comes time to fire, the traditional three-step orders of "Make Ready" "Present Arms" and "Fire" are used.
When ordered to "Make Ready" the musket is brought from the position of Shoulder Arms, trigger guard facing forward. The left hand grabs the firelock just forward of the trigger and lock, the right elbow raised and prepared for firing. The thumb is used to bring the firearm to full cock.
The order "Present" is an order of movement. The firelock is leveled with the enemy into a firing position. In doing so, the left hand slides foward from its position just forward of the trigger guard to a point further along the barrel. The exact point is different depending on the firearm, but often the trigger-most sling ring or the first barrel band closest to the musket's flintlock along the forestock are the preferred resting place. The whole body moves in one action in this order, and the right foot is shifted back by six inches. Further, the left hand does not actually grip the barrel, so much as simply hold it, hand flat, palm-up with the barrel resting across the palm.
Finally, when "Fire" is commanded, the trigger is pulled and the firelock is engaged. Until and unless a further order is given, the weapon is to remain leveled in the position of Present.
(Part 2 incoming) | [
"A muzzle loading weapon is loaded through the muzzle, or front of the barrel (or \"tube\" in artillery terms). This is the opposite of a breech-loading weapon or rifled breechloader (RBL), which is loaded from the breech-end of the barrel. The rifling grooves cut on the inside of the barrel cause the projectile to... |
How come there are no famous or well-known Civil War songs from the North? | So... this is one of those questions where I'm hard pressed to answer exactly as asked, as the premise is somewhat leading. When a question is "Why don't I know about [X]?", "Why wasn't I taught about [Y]?", and so on, the answer is often less about an overarching narrative than it is about your specific circumstances and what you were exposed to. If you grew up in Alabama, I would expect that you are well aware of "[Dixie](_URL_0_)", and if you grew up in Maryland, we can throw "[Maryland, My Maryland](_URL_5_)" into the mix, but growing up in New England, if you asked me to play "song association" with the American Civil War, I would probably tell you "[Battle Hymn of the Republic](_URL_4_)", a song I learned the lyrics to when I was quite young. I knew the words to Dixie too (I was a weird child! Don't judge me!), but that is somewhat beside the point.
I don't want to play 'which is more famous', as I'm not sure how easy it would be to measure that with precision here, but the point I do wish to make is that the North absolutely produced some recognizable songs. I would even be willing to make an argument that, while "Dixie" may have been propelled to immortality die to its association with the Confederacy, for which it served as an unofficial Anthem, it predates the CSA, while the abolitionist Julia Howe wrote "Battle Hymn" quite specifically in light of the war already commenced. Of course, Howe only wrote the lyrics, and she borrowed a tune from another song which is closely intertwined with the North, "[John Brown's Body](_URL_2_)"", which was more popular with the soldiers of the time, even if we remember Howe's more somber and religiously infused lyrics today. "John Brown" was a much more organic song, as well, with lyrics varying from unit to unit, and it isn't even entirely clear to to credit with originating it. The melody is even older, and likewise in question, although ironically at least one possible origin of the arrangement is a South Carolinian, William Steffe.
Dixie is also ironic in that regard, since it was likely written by a *northerner*, Daniel Emmett, for a minstrel show put on in New York City in the late 1850s, although there is question as to whether he was influenced by tunes he heard from a free black family that liked in his Ohio town growing up. In any case, itss popularity with the Confederacy irked Emmett, who would be a staunch supporter of the Union during the conflict. In any case though, the only main point I am making here is that Dixie predated the Confederacy. It is up to you how that affects its standing as a "Civil War Song".
I would, however, bring up one more Northern tune I feel has endured, "[When Johnny Comes Marching Home](_URL_1_)". Again, it comes down to a matter of exposure, but I think that it also stands as a tune which has survived to today, and as with Battle Hymn, it is both a song written during the war - not simply one which gained popularity during the time - and also likely not an original melody, as there is less clarity in the exact origin of the original tune here. "[Johnny Fill Up the Bowl](_URL_3_)", with basically the same melody, was more popular during the war (just like with "John Brown's Body", but "Marching Home" - certainly a commonly heard tune during the conflict - weathered time better in the years beyond, and gained new popularity a few decades later during the Spanish-American War.
There are other songs which were popular, and you might find reference to here and there, such as "Marching Through Georgia", but I think it is fair to say that "Battle Hymn"/"John Brown" and "When Johnny Comes Marching Home" are the ones which endured best, and which are most likely known to modern audiences. I can't say why *you* haven't heard them - although perhaps you have and didn't realize their origins - so could only speculate it to be some combination of geography and interests, but I certainly don't think it is fair to say the North left us with no famous songs from the war.
Christian McWhirter's "Battle Hymns: The Power and Popularity of Music in the Civil War"
Steven H. Cornelius's "Music of the Civil War Era" | [
"After the American Civil War, the song was documented more extensively. Joel Chandler Harris included a version of it in his \"Uncle Remus and His Friends\" (1892), and in 1915, E. C. Perrow included a version with his article \"Songs and Rhymes from the South\" in \"The Journal of American Folklore\". Dorothy Sca... |
Can someone explain DNA sequences? | Each side connects to a different carbon on the backbone, either 5' or 3'. Generally the convention is to express sequences from 5' to 3', so it'd be like 5' ATCGATCGATTACA 3'. The opposite strand would go 3' to 5'. | [
"Information on the distribution of nucleotides in a DNA sequence can be determined from the Z curve. The four nucleotides are combined into six different categories. The nucleotides are placed into each category by some defining characteristic and each category is designated a letter. \n",
"Formally, a DNA seque... |
why is a nation citizen id card in the us a bad idea? | there are millions of legal residents here that aren't citizens. they all can get a state ID or a driver license.
| [
"There is no compulsory federal-level ID card issued to all US citizens. US citizens and nationals may obtain passports or US passport cards if they chose to, but the alternatives described below are more popular.\n",
"BULLET::::- National ID card: The United States does not have a national ID card, in the sense ... |
Why did Carthage rely on mercenaries so heavily, while other Mediterranean powers of the same time seemed to be drawing more from their citizenry? | More input is always welcome; for the meantime, this answer by u/Jollydevil6 [on the Carthaginian army](_URL_0_) may be of interest to you. | [
"Carthage did not maintain a large, permanent, standing army. According to Polybius, Carthage relied heavily, though not exclusively, on foreign mercenaries, especially in overseas warfare. The core of its army was from its own territory in Northwest Africa (ethnic Libyans and Numidians (modern northern Algeria), a... |
Is USB charging more battery friendly than charging with AC charger? | There is a lot of different things going on. Devices which charge from USB get up to 500mA as a basic source. The device can negotiate for more current by asking for it. From an electronic design standpoint, it is more effort to put that into a design that normally doesn't communicate with a computer.
For a wall wart charger, you can simply supply as much current as the device will take.
What the device does with the current and how the battery charging is controlled by the device is a different matter. | [
"240 volt AC charging is known as Level 2 charging. Level 2 charging is similar to household appliances such as clothes driers. Level 2 chargers range from chargers installed in consumer garages, to relatively slow public chargers. They can charge an electric car battery in 4–6 hours. Level 2 chargers are often pla... |
why would seeing yourself when time traveling mess up everything? | If you saw yourself then that may alter the "timeline" that you've been on. Remember in the film Jurassic Park where the "butterfly effect" is explained? The idea is that a small alteration in the past (like seeing yourself) may have dire consequences on the future.
If you change this timeline when you travel to the past, then the future you return to might be drastically different.
| [
"The person affected by Alice in Wonderland syndrome may also lose a sense of time, a problem similar to the lack of spatial perspective. Time seems to pass very slowly, akin to an LSD experience. The lack of time and space perspective also leads to a distorted sense of velocity. For example, one could be inching a... |
if the moon's near side is locked onto always facing the earth, how does it rotate every month without us seeing the far side? | Because its rotation is sync'd up with its revolution around the Earth as you can see [here](_URL_0_). While the moon spins, it is also revolving around the Earth so that the same side is always facing us. | [
"The Moon is in synchronous rotation as it orbits Earth; it rotates about its axis in about the same time it takes to orbit Earth. This results in it always keeping nearly the same face turned towards Earth. However, because of the effect of libration, about 59% of the Moon's surface can actually be seen from Earth... |
why, when using the same tv and console, do i need the volume on, say 20 to watch netflix comfortably, but then on 40 or 50 to hear hbo go the same way? | When you watch certain videos on Netflix, the audio stream that comes with it may be louder than certain videos from HBO Go.
This tends to happen due to the loudness war, where producers try and make audio streams louder to attract your attention when flipping through the channels.
Audio streams should be recorded at a quiet so that when you turn the volume up it still sounds good. | [
"As of the end of 2016, the channel was the least-watched English-language channel on all of American subscription providers, averaging only 30–35,000 viewers on an average night in primetime (a decline of nearly a third from the already-low numbers VH1 Classic had netted in 2015), which was likely a factor in the ... |
So i tried applying super glue with a Qtip, moments later got a cloud of awful smelling smoke and the glue was almost instantly dried. Wtf? | Cyanoacrylate (crazy glue) [reacts](_URL_0_) strongly with cotton. | [
"The name derives from Genkem, a brand of glues which had \"become the generic name for all the glues used by glue-sniffing children\" in South Africa, where the drug originated and is most popular on the African continent today. In the book \"Children of AIDS: Africa's Orphan Crisis\" by Emma Guest, the making of ... |
Why has Texas become so much more prosperous than its Great Plains counterparts? | Central Texas is largely covered with cedar trees and oak groves (in the Hill Country), with large Cypress along the rivers. It can look Savannah-like when landowners clear all of the cedar in these places. Central Texas contains an abundant number pecan trees and other hardwoods, with large bald cypress along rivers. At least too abundant to be considered grassland, especially in populated areas.
Houston and much of the eastern third of Texas is more like Louisiana and other gulf states. this is generally seen from Dallas to the LA border, and all the way down to the gulf itself. Lots of forests, and some swamps. Forests here are mostly pine, mixed with hardwood forests as you go west.
So overall, Central and East Texas consist of landscapes that just don't fit a grassy description. What you're thinking of is the Panhandle, and that's a totally different landscape/climate, and is actually a part of the great plains. The state is so large that it also has desert areas in the far west (though some mountains in these areas have trees). | [
"Texas's large population, abundance of natural resources, thriving cities and leading centers of higher education have contributed to a large and diverse economy. Since oil was discovered, the state's economy has reflected the state of the petroleum industry. In recent times, urban centers of the state have increa... |
Can Animals Identify Their Younger Selves? | Most animals can't even identify themselves in front of a mirror. This includes dogs\cats\horses etc.
_URL_0_
From the wiki:
> Animals that have been observed to pass the mirror test include:
>
All great apes:
Humans – Humans tend to fail the mirror test until they are about 18 months old, or in what psychoanalysts call the "mirror stage".[2][3][4]
Bonobos[14]
Chimpanzees[1][14][15]
Orangutans[16]
Gorillas – It was initially thought that gorillas were unable to pass the test, but there are now several well-documented reports of gorillas (such as Koko[17]) passing the test.
Bottlenose dolphins[18]
Orcas[19]
Elephants[20]
European Magpies[21]
| [
"\"Gelyella\" shows some paedomorphosis, in which animals reach sexual maturity while still partly resembling juveniles. The adults are long with a nearly cylindrical body that tapers towards the rear. There are eleven body segments, the last of which is the length of the previous two segments combined.\n",
"A ju... |
What are some examples of 1920's swing-dancing clothing? | Skirts, trousers, shirts...what exactly are you looking for, here? [this](_URL_0_)? | [
"Swing dance is a group of dances that developed with the swing style of jazz music in the 1920s–1940s, with the origins of each dance predating the popular \"swing era\". During the swing era, there were hundreds of styles of swing dancing, but those that have survived beyond that era include: Lindy Hop, Balboa, C... |
Do other animals get stretch marks? if not, why? | Yes. Rolls Royce only use bull hides in the leather on their cars because female cows can get stretch marks more easily, just like human women. To my understanding, stretch marks are scars from skin being stretched until it breaks. You can get them from gaining weight quickly and this happens more to females than males because of pregnancy. Males get them too though. Dogs can also get stretch marks but I'm not sure about other species besides those two. | [
"Because it does not stretch, animals are less likely to become entangled in HT wire. However, for the same reason, if an animal does become entangled or runs into a few strands at a high speed, it can be deadly, and is sometimes referred to as having a \"cheese slicer\" effect on the animal.\n",
"Anoles are harm... |
What are the most interesting human artifacts with uses that are unknown or disputed? | Stone Henge. Scientists have used computer models to see what the sky looked like when stone henge was built. The stars were in different positions thousands of years ago so scientist have to rethink what it was pointing to and what made those stellar objects so important. | [
"Of the myriad artifacts displayed within the museum, the most peculiar were a reconstructed panther skeleton, a collection of grapefruit-sized turquoise malachite eggs, fossilized elephant bird eggs, unexploded military mortar shells, an elephant skull with jaw-bone, dried elephant dung balls, a stuffed dingo, and... |
Expansion of space ≈ contraction of Planck length? | Well the short answer is no. The Planck length is just a length you get by combining three of the constants of our universe, G, h and c (gravitational constant, Planck's constant (quantum of action), and the speed of light). We could rearrange them a bit and come up with a mass of a few micrograms, but that's no more a fundamental mass than anything else.
What the expansion of the universe is saying is that if I measure the distance between two distant points with little mass between them, wait some time and measure the distance again, then the distance will have grown. So 2a is the accepted answer within the field | [
"The Planck length is the scale at which quantum gravitational effects are believed to begin to be apparent, where interactions require a working theory of quantum gravity to be analyzed. The Planck area is the area by which the surface of a spherical black hole increases when the black hole swallows one bit of inf... |
why is it that when an object falls from orbit, it goes faster than terminal velocity? | Terminal Velocity is the point where gravity cant pull you faster through whatever material you are falling from.
Normally this is air, but in orbit there is much less air and thus less stuff to fall through, thus you can fall faster. | [
"The terminal velocity of a falling body occurs during free fall when the force due to gravity is exactly balanced by the force due to air resistance, such that the body experiences zero acceleration. The formula for terminal velocity (where buoyancy in air is negligible) is given by the thrust\n",
"As the speed ... |
Can someone explain the galaxy rotation graph? | > v = sqrt(GM)/sqrt(r)
This would be the correct orbital equation if all the galaxy's mass were concentrated in a point at the center. Now, there is a black hole at the center, but [its mass](_URL_0_) is no more than a few millionths of the of the [total mass of the galaxy](_URL_1_): most of the mass is spread out across the bulge and disk.
So the rotation speed graph is a tradeoff between the mass distribution and the inverse square law. It's [roughly true](_URL_2_) that any given star orbits around the *combined mass of all the stars inside its orbital radius*: the effect of the stars outside that radius tend to cancel out. So as you go further from the center, there are more stars inside the orbit contributing mass to the "M" in your equation, and that effect overwhelms the "r" in the denominator. But as you get out into the galaxy's sparse outer reaches, there's less additional "M", but still more "r", so the velocity starts to decrease.
But the idea of dark matter is that there *is* more mass out at large radius that we can't see, which makes the galaxy rotate faster out there than expected. | [
"The galaxy rotation problem is the discrepancy between observed galaxy rotation curves and the theoretical prediction, assuming a centrally dominated mass associated with the observed luminous material. When mass profiles of galaxies are calculated from the distribution of stars in spirals and mass-to-light ratios... |
why are there different levels of spf in products? why is the highest not always the best? | Higher SPF sunscreens will prevent tanning, and a lot of people want to tan a little when they are out in the sun. Maximum SPF value is good for young kids, people with sensitive skin, people with a predisposition to skin cancer, and people working for long periods in the sun. For people who just want to tan a little without burning a lower SPF value is better. | [
"Some studies have shown that people commonly apply only 1/4 to 1/2 of the amount recommended for achieving the rated sun protection factor (SPF), and in consequence the effective SPF should be downgraded to a square root or 4th root of the advertised value. A later study found a significant exponential relation be... |
Via a similar process to electrolysis, could we extract a viable amount of oxygen out of CO2? | Yep, it's mainly called artificial photosynthesis, and it's arguably the largest unsolved problem in the field of inorganic chemistry. State-of-the-art systems can only consume millimole per hour quantities of CO2, which is obscenely slow, for a bunch of reasons. | [
"In addition to reduce the voltage required for electrolysis via the increasing of the temperature of the electrolysis cell it is also possible to electrochemically consume the oxygen produced in an electrolyser by introducing a fuel (such as carbon/coal, methanol, ethanol, formic acid, glycerol, etc.) into the oxy... |
during traffic stop how police communicate with drivers who don't speak english? | Police departments actively hire officers who speak the languages common in the area, and offer a salary bump to ones who learn them. One of them would be called in as a translator if necessary.
And even the officers who don't understand the language will have a cheat sheet and quickly learn the common phrases they need to know. | [
"BULLET::::- In England Traffic officers are employed by Highways England and maintain traffic flow on trunk roads and some bridges and tunnels. There are different types of traffic officer and they are appointed under separate Acts. They have limited powers to direct traffic and place road signs, close lanes of an... |
how did humans train horses to willingly charge into danger or death? | Horses, like all animals, don't have a concept of their mortality.
They have instincts which tell them to avoid trouble that helps keep them alive.
However once you get a horse used to the sounds of warfare, they'll charge right in to wherever you point them.
Horses that were too scared simply wouldn't be used. | [
"Once humans domesticated horses, that animal became a favorite way to escape a crime scene. Jesse James and many old \"Wild West\" bank robbers and train robbers of the 19th century used horses to get way from the scene of their larceny.\n",
"The primary purpose of training horses is to socialize them around hum... |
Considering the enormous number of memories we retain into old age, what was all of that brain matter being used for before these memories were stored? | Memory is a huge and complex topic which is not well understood. There are different kinds of memory, but you seem to be asking about [long-term explicit memory](_URL_2_).
Speaking mostly from the realm of artificial neural networks, which are only loosely modeled on brain physiology, I think the most concise answer to your qeustion is that individual memories don't really "take up space," but can be thought of more as additive, like waveforms.
If you're familiar with audio signals and [Fourier analysis](_URL_1_), a note sounding in a room doesn't "take up" the room; although everything is resonant, there's "room" for other sounds at the same time. A single musical instrument typically creates a plethora of different resonances which exist together in the same space more or less independently, vibrating the same air. Similarly, a single wire can cary many different frequencies of signal independently.
Getting a little more technical, the "space" which you run out of when adding too much information in this model is a ["phase space"](_URL_0_) rather than physical space. Most likely, you lose the ability to distinguish between a large amount of overlaid information before you reach any physical limits on the underlying mechanisms by which the information is stored.
| [
"Research focused on gaining a better understanding of what memories are has been going on for many years, in this way so has research in memory erasure. The basis for the recent history for memory erasure has been focused on determining how the brain actively keeps memories stored and retrieves them. There have be... |
Nazi literature, poetry, films or other artistic works? | Though it doesn’t get into what ultimately became of Nazi books, films, and artwork after the war, you should definitely take a look at u/commiespaceinvader’s in-depth response to [Were there any truly talented Nazi artists, musicians, or writers who would be renowned if not for their political views?](_URL_0_), where he discusses and gives examples of Nazi art and aesthetics, and talks about what happened after the war to some of the artists associated with the ideology. | [
"It took four years to \"refine\" the Nazi art criteria; in the end what was tolerated was whatever Hitler liked, and whatever was most useful to the German government from the point of view of creating propaganda. A thorough head-hunting of artists within Germany was in effect from the beginning of the Second Worl... |
What are the other names for "The Great War"? | It was in the early days called "the war to end war," or "the war to end all wars" - in optimism that it would be the last. However (even during the war), as it became apparent WWI would not, in fact, end war, the term became used more sardonically. | [
"In this series, the war remains known as \"The Great War\" and the term \"World War\" never comes into use. When a second war of comparable proportions breaks out twenty years later, it get named \"The Second Great War\" and the earlier one becomes retroactively \"The First Great War\".\n",
"The war has been des... |
how to progressively learn math. | Go to any university website and then look up the books from the lowest mathematics course, which is probably "introduction to trigonometry", to whatever is offered in the Ph.D courses. When learning from these books, do the exact opposite of what you would do in university. Study them to learn and to learn it well. Don't just skim a chapter and say "yep, I got it". Do every single exercise until you know why and exactly why you are doing what you are doing. | [
"The principles of mathematics are generally understood at an early age; preschoolers can comprehend the majority of principles underlying counting. By kindergarten, it is common for children to use counting in a more sophisticated manner by adding and subtracting numbers. While kindergarteners tend to use their fi... |
why is there an apparent war between pc gamers and developers? | Ignoring piracy when answering that question is kind of counter intuitive because its the single biggest reason. Pirating on PC is significantly easier then on any other platform. Developers see this as disincentive to working for that platform. It's also harder to develop for PC because there is a huge amount of possible configurations you need to make your game work on.
It's always seen as more profitable to develop for consoles and port to PC.
Others have mentioned things like DLC and I'd add preorders as anti consumer practices. The simple fact is for a huge portion of the player base these are not problems. Developed will keep doing it until its not profitable. At the moment its very profitable.
One of the biggest advantages of PC is the mod scene. The problem there is companies have no incentive to support one. Look at a single player game like skyrim. Mods have kept that game alive for years, but the developed don't get anything from that. After they make a sale of the game they have no further interest in the user. Valve attempted to address the issue by providing an incentive for developed to make and support modding tools but the community recoiled in horror.
There is no war, PC is healthy, plenty of Indy studios, some super successful free to play games with good models, strong esports scene. It's just a secondary platform for big triple A devs.
| [
"PC development is different. Game developers try to account for majority of configurations and hardware. However, the number of possible configurations of hardware and software inevitably leads to discovery of game-breaking circumstances that the programmers and testers didn't account for.\n",
"The change of foc... |
What is the highest frequency of light that the human eye can detect/process? What is the lowest? | We can only see visible light, roughly 390 to 700nm in wavelength. 3x10^8 / 390x10^-9 gives the highest frequency. 3x10^8 / 700*10^-9 will give the lowest frequency. This [wikipedia picture](_URL_1_) does a good job showing the three cone cells and their contribution to our perception of [visible light](_URL_0_). | [
"The commonly stated range of human hearing is 20 Hz to 20 kHz. Under ideal laboratory conditions, humans can hear sound as low as 12 Hz and as high as 28 kHz, though the threshold increases sharply at 15 kHz in adults, corresponding to the last auditory channel of the cochlea. Humans are most sensitive to (i.e. ab... |
elliptical curve cryptography - how does it work? | OK, first off it's "elliptic curve", not "elliptical curve". An elliptic curve is the collection of points (x, y) in the plane that satisfy
y^2 = x^3 + ax + b
together with a special point (∞, ∞). Different choices of a and b give different curves. I'll talk about the elliptic curve version of Diffie-Hellman key exchange, since it's the simplest protocol and illustrates the fundamental ideas.
Everyone using the system agrees on a, b, and some point p on the curve. The fundamental operation is called "point addition". To add two points, you draw a line through them; by the curve's construction, any line through them will intersect the curve in exactly one other point. You reflect that new point across the x axis, and that's the result of the addition.
I pick a random counting number x and use "point addition" to calculate xp, i.e. p added to itself x times. You pick a random number y and calculate yp. I send you xp, you send me yp. I then compute x(yp) and you calculate y(xp). We clearly get the same answer and use it as a secret key.
The reason this is secure is because it's hard to figure out what x is even if you know p and xp, so anyone who sees what numbers we exchanged can't figure out our secrets x and y. I can't figure out your x and you can't figure out my y.
| [
"In mathematics, the Jacobi curve is a representation of an elliptic curve different from the usual one (Weierstrass equation). Sometimes it is used in cryptography instead of the Weierstrass form because it can provide a defence against simple and differential power analysis style (SPA) attacks; it is possible, in... |
How/Why can matter go from a solid state to a gaseous state? Completely skipping over liquid, and vice versa...? | Molecules will occupy a state of aggregation to minimise their free energy. For particular conditions of T and P, this is a trade off of energy and entropy. For some molecules, the additional reduction in entropy by going directly to a solid is more than offset by the reduction in enthalpy so the molecules prefer to be in a solid rather than liquid form. | [
"Historically, the distinction is made based on qualitative differences in properties. Matter in the solid state maintains a fixed volume and shape, with component particles (atoms, molecules or ions) close together and fixed into place. Matter in the liquid state maintains a fixed volume, but has a variable shape ... |
why does yahoo answers rate higher than reddit? | So let's say Yahoo!, Google, and Reddit are prominent families in the neighborhood. All three are well-known around town and are trusted more than other families (sites). Each family also has their own strengths and weaknesses as well as kids (subdomains/subreddits) who specialize in certain areas. The Google family is mostly well-known because of Search, the head of the family who has an extremely wide network and helps people find information they need from, for the most part, reputable sources. The Yahoo! family has this kid named Answers who is known for answering people's questions, though the answers aren't really of their own. Still, since the Yahoo! family is relatively respected, a lot of people come to Answers for their questions and sometimes share answers of their own.
Now let's say you approach Search with a question, say, "Why is the sky blue?" While Search will probably refer you to a number of their contacts who specialize in science, such as NASA, they would also refer you to Answers, especially if they know that Answers has answered a question with that exact wording. Even if both families have their differences, Search still recognizes that Answers is a valuable contact. While the Reddit family has an offspring that also has answers to questions, ELI5 (~2 years old), Answers (~ 8 years old) is much more established. In addition, the Reddit family isn't as prominent as the Yahoo! family yet. A lot of other families refer their own visitors and guests to the Yahoo! family much more than they do to the Reddit family. Not to mention that they have been doing so for years.
---
The age of one's website isn't as important as I make it seem in this explanation with search engine performance but it was the best that I could do to contrast the level of acceptance of both sites as a source for information. There are also other numerous factors, as SEO people would let you know, that would increase how established one "family" or "child" is. Here's some search engine metrics regarding both:
Reddit Moz Domain Authority: 99/100
ELI5 Moz Page Authority: 74/100
Domains linking to Reddit in the past 5 years: ~2.5 million
Yahoo! Moz Domain Authority: 100/100
Answers Moz Page Authority: 94/100
Domains linking to Yahoo! in the past 5 years: ~9.7 million
EDIT: Thanks for the gold! :)
EDIT2: Grammar | [
"This \"Internet language\" of incorrect spelling and improper grammar also contributes to Yahoo! Answers' reputation of being a source of entertainment rather than a fact based question and answer platform, and for the reliability, validity, and relevance of its answers. A 2008 study found that Yahoo! Answers is s... |
In movies, there's frequently a standoff with two people pointing a gun at each other. Is human reaction time quick enough for the second person to get their shot off before dying if the first fires and hits them in the head? | Really depends on the guns and distance involved.
From one source, we see bullet speeds ranging from ~180 m/s (.38 special) to ~1200 m/s (.22 swift) (Petzal, 1992).
Eckner, Kutcher, and Richardson (2010) found that people respond to visual stimuli at ~270ms, but earlier studies found reaction times closer to 190ms (e.g., Galton, 1890; Welford, 1980).
I would add that the reaction times above are averages across populations, and that outliers on Human Benchmark's (2014) data set on reaction times consistently react at 130ms or faster. Presumably, world class gunfighters and spies will cluster closer to this number (130ms) than the ~270ms number found in NCAA football players by Eckner, et al. (2010).
Let's be charitable and use the slowest gun (180 m/s) and assume we're dealing with world-class gunfighters (130ms RT). To be able to respond before the bullet hits (which presumably would mess with accuracy, etc), our hypothetical stand-off standers would need to be about 24 meters away from each other if your only concern is a voluntary response.
**References:**
Eckner, J. T., Kutcher, J. S., & Richardson, J. K. (2010). Pilot evaluation of a novel clinical test of reaction time in National Collegiate Athletic Association Division I football players. *Journal of Athletic Training*, 45(4).
Galton, F. (1890). Exhibition of Instruments (1) for Testing Perception of Differences of Tint, and (2) for Determining Reaction-Time. *Journal of the Anthropological Institute of Great Britain and Ireland*, 27-29.
Human Benchmark. (2014). *Reaction Time Stats* [Data set]. Available from _URL_0_.
Petzal, D. E. (1992). How fast is a speeding bullet. *Field and Stream*, 97, 23.
Welford, A. T. (1980). *Reaction times*. London, UK: Academic Press | [
"Suddenly, they turned around, got on their knees, as if they were ordered to, they did it all together, aimed. And personally, I was standing there saying, they're not going to shoot, they can't do that. If they are going to shoot, it's going to be blank.\n",
"A reaction shot usually implies the display of some ... |
Did the ancient Romans probe far beyond the borders of their empire? | Yes, the Romans were quite nosy. I've made a couple of comments on this subject ([1](_URL_0_), [2](_URL_1_)). To reiterate myself (sorry for this comment being a bit of a mishmash):
The Romans actually invaded Arabia during Augustus' reign, under a commander named Gallus, and even besieged the city of Ma'rib in Yemen. The expedition was a failure (mainly due to lack of water), but we have a good record of it because Gallus was friends with the historian Strabo.
The Romans were also quite active in trade, particularly the Indian Ocean trade network. To quote myself:
> The Romans traded extensively in the Indian Ocean Trade Network, as detailed in *Periplus of the Erythraean Sea* (The Red Sea, Arabian Sea, and Indian Ocean). Roman coins have been [found in Madagascar and several other sub-Saharan African places](_URL_3_), which goes to show how extensive the ancient trade networks really were (the link I give suggests that the coins were brought by Arab traders, as the Romans traded extensively along the Red Sea). [There were several trade posts detailed in *Periplus of the Erythraean Sea* along the Somalian coast that traded up the Red Sea with Rome](_URL_2_).
There's also been Roman pottery found in India, and Strabo talks about the Indian-Roman trade:
> As for the merchants who now sail from Egypt by the Nile and the Arabian Gulf as far as India, only a small number have sailed as far as the Ganges; and even these are merely private citizens and of no use as regards the history of the places they have seen. But from India, from one place and from one king, I mean Pandion, or another Porus, there came to Caesar Augustus presents and gifts of honour and the Indian sophist who burnt himself up at Athens, as Calanus had done, who made a similar spectacular display of himself before Alexander.
> *Strabo, Book XV: On India*
There are also *possible* Roman trading posts in India.
Here's Cassius Dio on Indian ambassadors traveling in the Roman Empire and seeking an audience with Augustus (I know that's technically the opposite of what you're looking for, but oh well, it's interesting):
> [...] and he [Augustus] also attended to many matters of business. 8 For a great many embassies came to him, and the people of India, who had already made overtures, now made a treaty of friendship, sending among other gifts tigers, which were then for the first time seen by the Romans, as also, I think by the Greeks. They also gave him a boy who had no shoulders or arms, like our statues of Hermes. 9 And yet, defective as he was, he could use his feet for everything, as if they were hands: with them he would stretch a bow, shoot missiles, and put a trumpet to his lips. How he did this I do not know; I merely state what is recorded. 10 One of the Indians, Zarmarus, for some reason wished to die, — either because, being of the caste of sages, he was on this account moved by ambition, or, in accordance with the traditional custom of the Indians, because of old age, or because he wished to make a display for the benefit of Augustus and the Athenians (for Augustus had reached Athens);— he was therefore initiated into the mysteries of the two goddesses, which were held out of season on account, they say, of Augustus, who also was an initiate, and he then threw himself alive into the fire.
Speaking of China, Homer Dubs proposed a quite radical theory (dismissed by nearly everyone, as far as I know) that hypothesizes captured Roman legionaries from the battle of Carrhae were used as mercenaries by the Parthians on their eastern frontier, where they skirmished with the Chinese (one of Dubs' sources is a Chinese account which mentions soldiers fighting in a "fish scale" formation; aka testudo).
| [
"The Roman Empire had reached its greatest extent under the Emperor Trajan. However, before Trajan, the Emperor Augustus set about stabilizing the frontiers of the Empire. As a result, the Romans were more interested in simply defending their territory and consolidating the Empire rather than in attempting to conqu... |
what exactly is a continent? just a part of the earth that rises above water? how was the first continent made? | > why was it all lumped together on one side of the earth in the beginning? Wouldn't it be random?
It wasn't the beginning. There were [a bunch](_URL_0_) of continents and super continents before Pangaea. Ever since the surface of the earth cooled and cracked, about every 450 million years or so, the continents go though a cycle where they all end up on one side of the planet, and then it gets really hot underneath the blanket-like pile of continents that make up the current supercontinent and it them apart, pushing the pieces to the other side of the planet where they bunch up again and the process starts over.
As to how the continents formed, they probably formed of lots of "little" masses of less dense granitic rock, which means that they can't sink and remelt like the denser basaltic rock (what's under the oceans now) can. So, the less dense rock just basically stayed around forever (unless they erode), and rammed into the other piles of less dense rock making even bigger piles of never-sinking rocks. Big piles combined with other big piles to make even bigger piles, (think how India, which used to be its own continent, slammed into and meshed with Asia) and so on and so on until we got big continent-sized piles of non-sinking rocks, which now "float" around on bits of crust.
As to what is a continent, that is highly debated. I prefer the definitions of a continent as being the largest craton (very big, very old chunk of non-sinking rock) on a particular plate. So, North America, South America, Africa, Eurasia, Antarctica, and Australia/Oceania. | [
"The Earth's continents started to form in the Archean, although details about their formation are still being debated, due to lack of extensive geological evidence. One hypothesis is that rocks that are now in India, western Australia, and southern Africa formed a continent called Ur as of 3,100 Ma. A differing co... |
why does de-fragmenting a solid-state drive reduce it's lifetime? | Life span of a solid state drive is determined by how many times each unit of storage can be read and written to.
All de-fragmentation takes parts of files that that have been stored all over and re-arranges them so they are all together.
This requires a lot of reading and writing of large areas of the Solid state drive.
Also the primary reason to defragment is to improve seek times for older spinning drives that physically need to move a read head back an forth to find chunks of data. Having them all together improves spindle drives efficiency.
Nothing moves in a solid state drive so grouping the data has little performance improvement.
You may still want to defragment an SSD drive to improve taking backup images, or if you need to resize a partition. | [
"Solid state drives have set new challenges for data recovery companies, as the way of storing data is non-linear and much more complex than that of hard disk drives. The strategy the drive operates by internally can largely vary between manufacturers, and the TRIM command zeroes the whole range of a deleted file. ... |
What did the Romans think of Stonehenge? | [A similar question was asked a couple of years ago.](_URL_0_) I second u/QVCatullus in that I don't believe there are any Ancient Roman mentions that we know of currently. Not saying that there aren't any, but we presently don't know what they thought of it. | [
"In 1655, the architect John Webb, writing in the name of his former superior Inigo Jones, argued that Stonehenge was a Roman temple, dedicated to Caelus, (a Latin name for the Greek sky-god Uranus), and built following the Tuscan order. Later commentators maintained that the Danes erected it. Indeed, up until the ... |
Are there any statements or interviews by the pilot/plane crew who dropped the atomic bombs on Hiroshima and Nagasaki | There have been many, many interviews with these people since 1945. They have not been, on the whole, reclusive. The Atomic Heritage Foundation has a [great oral history website](_URL_0_) of people who were involved in the development and use of nuclear weapons during World War II. If you click "filter by subject" and select "Hiroshima and Nagasaki missions" and then click "apply" you will get a lot of them. | [
"Flown by 393d commander, Major Charles W. Sweeney, it was assigned to the Hiroshima mission on 6 August 1945, as the blast measurement instrumentation aircraft. On the mission to bomb Nagasaki on 9 August 1945, it was to have been the aircraft carrying the bomb, but the mission schedule had been moved forward two ... |
Why did Pangea break apart and the continents move away in such a manner as if they were "floating", without regard for what lies underneath the ocean? | Alright, strap in, we have a lot of ground to cover before we can answer your question fully. First, there are two broad kinds of crust, continental and oceanic, which differ in their composition, densities, and other physical properties. [Continental crust](_URL_4_), which forms the bulk of areas above sea level, is generally thick (30 km up to nearly 100 km in isolated areas) and relatively light in terms of density (~2.7 g/cm^3). [Oceanic crust](_URL_8_), which floors the ocean basins, is thinner (5-10 km) and denser (~2.9 g/cm^3).
[Tectonic plates](_URL_7_) almost always contain portions that are both oceanic and continental crust (though there are some exceptions, the Nazca, Juan de Fuca, Phillipine, and Pacific plates are almost entirely oceanic crust with no or very small bits of continental crust largely along their edges). By definition, a given plate largely behaves as a rigid object (i.e. if one part of the plate is moving , the other parts of the plate are also moving), in detail these movements are largely rotations (consequence of movement on a sphere) so different parts of a plate are moving at different rates and directions AND there is some internal deformation of plates (not all active fault zones are at the boundaries of plates), but for our purposes, let's just think of a plate as a rigid object experiencing a rotation so that **if a force acts on one part of a plate, the entire plate will move in response to that force**.
Now we can start putting these bits together to understand the drivers of plate motion (which is ultimately what your question is about). There are three primary drivers for plate motion that have been identified: basal traction, ridge push, and slab pull. **Basal traction** is a force imparted to the base of plates by movement of the [mantle](_URL_3_. The mantle is convecting, ultimately a consequence of the thermal gradient between the core (very hot) and the surface (very cold) of the earth and the top of these convection currents are parallel to the surface of the earth along the base of plates, potentially 'dragging' plates along (an aside, the mantle is solid, the plates are not, under any circumstances, 'floating on magma', the mantle behaves like a [rheid](_URL_5_), a solid that flows on long time scales). **Ridge push** is the idea that a plate is 'pushed' away from [mid-ocean ridges](_URL_2_), which is where new oceanic crust is produced via melting of mantle material. If you have a plate whose oceanic crust is growing on one side, pushing the plate and growing its surface area, you need a corresponding mechanism to reduce the surface area of that plate (or adjacent plates) because the total surface area of the Earth is fixed. That mechanism is [subduction](_URL_6_), which also provides our last driving mechanism slab pull. **Slab pull** is a force generated by the sinking of a portion of the oceanic crust. To understand why it sinks, we need to consider the density contrasts at the beginning. If oceanic and continental crust are juxtaposed across a plate boundary and the plate motion is such that they are being pushed into each other, the tendency will be for the denser (oceanic) plate to go under the more buoyant (continental) plate (i.e. subduction). This also occurs where two parts of oceanic crust meet, here the density contrast is controlled by the age, older and cooler oceanic crust being denser than younger and hotter oceanic crust, and this corresponds to distance from a mid-ocean ridge (i.e. how long has it been since the two bits of oceanic crust formed and how much have they cooled). Once subduction starts, you now have a portion of oceanic crust sticking into the mantle (a slab), and specifically into a relatively hot and less dense portion of the mantle called the aesthenosphere so the oceanic crust that is now there is actually denser (largely because of the temperature difference) than the aesthenosphere so it continues to sink and exerts a pull force on the rest of the plate to which it is still attached. Generally, the density contrasts between earth materials make it so that it is really hard to subduct continental crust (i.e. continental crust is very buoyant), so continental crust tends to stick around whereas oceanic crust is constantly being created at ridges and recycled back into the mantle at subduction zones, the oldest oceanic crust is around 200 million years, whereas we have bits of continental crust going back > 3 billion years.
All of the above forces act on a plate, however, we think most of plate motion is driven by slab pull, with ridge push and basal traction being much lesser in importance.
Ok, lets return to the question. We have Pangea, which was formed when a series of ocean basins (oceanic crust fringing continental crust) were consumed via subduction, eventually leading to the collision of various continental portions of plates and forming a 'supercontinent' (i.e. all of the main bits of continental crust stuck together) with a huge ocean basin covering the rest of the globe ([Panthalassa](_URL_0_)). All of the plate motion driving processes are still happening, we still have subduction of oceanic crust happening within the various plates that make up the Panthalassa ocean, etc. The break up of Pangea was driven by rifting, i.e. the formation of extensional faults driving thinning of continental crust and eventually forming a mid-ocean ridge and new oceanic crust, i.e. the East African Rift as a modern day example. The ultimate driver behind rifting (in this case and more generally) is still a topic for discussion. Is it entirely driven by slab pull forces at the 'opposite end' of plates? Is this a case where mantle forces are more important? We don't entirely know and there is probably not a single answer, but once we have the rifts going we have all of our familiar forces acting on our plates pulling plates on one side by slab pull and pushing via the newly formed ridges. The formation and break up of Pangea is not an isolated event, there have been several supercontinents which have formed and then been destroyed, in what is called the [Supercontinent or 'Wilson' Cycle](_URL_1_).
| [
"The break up of Pangea occurs during the Kimmerian tectonic phase for most of the Mesozoic, until the early-mid Cretaceous, this marks the start of creating the present position of our continents today. During the Jurassic, rifting activity reaches its maximum and North America starts to move apart from Eurasia fo... |
Is it possible to be allergic to electricity? | It is not possible to be allergic to electricity as electric currents do not interact chemically or physically in a way that would provoke an allergic response. You might provoke some sort of response with a high current through an electrical burn or overstimulation of neural pathways but this would not constitute an allergy. | [
"It is possible that even in people without direct evidence of allergy, the allergic response may be playing a role in acute coronary syndrome: markers of mast cell activation are found in people with ACS.\n",
"An allergic reaction can be caused by any form of direct contact with the allergen—consuming food or dr... |
why are there time zones within the continental us with a one hour spacing? | The choice is really a bit arbitrary--but the fewer time zones, the simpler everything is to manage. There are a few places with 30-minute or even 15-minute offsets, but on the whole one-hour time zones have become the global norm. It strikes a good balance between convenience of administration and keeping track with the solar time.
> What if there are cities which span areas falling into two time zones?
Time zones are not directly drawn based on longitude but set by law, usually at the convenient border of a jurisdiction, like the state or city limit. This means they usually deviate a little from the idealized 24-hour time zone division of the earth. | [
"Today, all nations use standard time zones for secular purposes, but they do not all apply the concept as originally conceived. Newfoundland, India, Iran, Afghanistan, Burma, Sri Lanka, the Marquesas, as well as parts of Australia use half-hour deviations from standard time, and some nations, such as Nepal, and so... |
How were monarchies first established after the fall of the Roman Empire? | The early feudal-type system ('feudalism' as an all-encompassing description of medieval society is a disputed subject these days) that the later monarchies rose out of largely came out of the late Roman Empire's villa system (which involved a landowner and hired 'peasants' working said land). In an effort to keep the production of food steady, emperor Diocletian had peasants tied to the land so they (and their descendants) had to continue farming - they couldn't choose a different profession. Other emperors added further laws that solidified the state of affairs.
After the fall of the Roman Empire, some of the landholders changed but the underlying social condition stayed the same. Over time, powerful individuals and dynasties collected the motley assortment of fiefdoms and manors under single rulers. A great example of this is Clovis, who consolidated the many Frankish "kings" (who were, for the most part, tribal chieftains) under a single ruler which would eventually become the basis for both France and the Holy Roman Empire.
In other areas, like Wales, people who had comparably less Romanization reverted to their historical tribes and formed kingdoms out of their ancestral lands (ironically, the infighting between these Welsh kingdoms was partly responsible for their failure to stop the Anglo-Saxons from setting up their *own* kingdom in Britain).
For the most part, the early monarchies rose out of families/tribes/peoples who were already powerful during the last days of the Roman Empire (even groups who were affiliated with the Roman state) who were able ride out the collapse of the Western Empire and then consolidate their power and expand to encompass less powerful groups/tribes.
[Edit] For an even clearer explanation of how these Germanic rulers worked from within the Roman system, both before and after the 'collapse', see /u/bitparity's comment below. | [
"In the ancient Kingdom of Rome, the kings were elected by the Assemblies. Once the Roman kings were overthrown, there remained an absolute prohibition for royal establishment in the Roman constitution, a prohibition which formally remained in place during imperial times, both Roman and Byzantine. In practice, howe... |
how can the us have so much foreign debt yet still be the most economically powerful nation in the world? given the current trajectory, how much longer will this last? | The US actually has a lower debt than Germany, Canada, Egypt, Spain, France, The UK, Singapore, Greece, Japan, and a host of other countries. When we look at public debt we do not compare total debt between countries, we compare debt to GDP (Gross Domestic Product). In that metric the US is actually in very good standing compared to a lot of other large economies. | [
"The total national debt of the United States in the United States was $18.527 trillion (106% of the GDP) in 2014. The United States has the largest external debt in the world and the 14th largest government debt as a % of GDP in the world.\n",
"The national debt rose $238 billion (or about 60% of the new debt ce... |
what causes rhotacism? (the inability to pronounce the letter “r”) | It is dependent on how you hear sounds and the way you were raised. If your family mostly uses trilled R’s then you would have a slightly higher chance of developing it. This is abundant in Asian countries.
A better explanation would be from this video:
_URL_0_ | [
"In medical contexts, rhotacism () is the inability to pronounce or difficulty in pronouncing \"r\" sounds. Speech pathologists call the condition \"de\"-rhotacization, because the sounds lose their rhotic quality rather than becoming rhotic.\n",
"In English, the most common occurrence of this type is a pronuncia... |
the difference between 3/4 and 6/8 timing in music. | They each contain the same amount of [eighth](_URL_3_) notes but it's how they're grouped. 3/4 is the traditional notation where the [quarter](_URL_0_) note is the beat: [eighth-eighth](_URL_1_) eighth-eighth eighth-eighth (2 eighth notes = 1 quarter note hence the notation 3/4). 6/8 on the other hand is grouped into triplets: [eighth-eighth-eighth](_URL_2_) eighth-eighth-eighth (tri-pl-et tri-pl-et).
Eighth no longer looks like a word. | [
"In music, the septimal major third , also called the supermajor third (by Hermann Helmholtz among others) and sometimes \"Bohlen–Pierce third\" is the musical interval exactly or approximately equal to a just 9:7 ratio of frequencies, or alternately 14:11. It is equal to 435 cents, sharper than a just major third ... |
How important was the Eichmann Trial in public awareness of the Holocaust? | I know this is over a week old, but I didn't want to leave this question unanswered.
From the end of the war until the Eichmann trial, the world obviously knew of the Holocaust and the general horrors that had occurred. Perhaps they knew someone that had been a victim of the Holocaust and so they knew some specific details. Other than that, they knew details primarily from news stories. However, many survivors of the Holocaust (and perpetrators/bystanders) preferred to keep quiet about what had actually occurred. Understandably, the survivors did not want to relive their trauma and they generally wanted to rebuild their lives. While some survivors were telling their stories and recording what had happened, the general consensus was to focus on the present and the future, not the past.
A bit of a digression here, but I think its important to point out why survivor testimony is so essential. Until this point, most factual records of the Holocaust were coming from the Nazis themselves. This was putting the story of the murder of millions into the hands of those that had done the murdering, not the victims/survivors themselves. Also, when a survivor tells their story, it can also be therapeutic (commonly accepted practice in psychology). So while it may be uncomfortable for other to hear the experiences from those who lived it, is is extremely important. Finally, survivor testimony is essential to serve as proof for the horrors that had occurred. For example, its pretty hard to deny the existence of gas chambers when hundreds (thousands? millions?) of people reported seeing and smelling them with their own eyes (sorry conspiracy theorists!).
Now as to whether or not survivor accounts were common before the war. Nowadays, rather than simply relying on survivor testimony to learn what had happened, we also have diaries, artifacts, records, etc. However, these things take time to come to light and so were not immediately available after the Holocaust. Again, many people wanted to try and simply forget about these events and move forward with their lives. People maybe spoke about what had happened to friends/family, but it was not as widespread as it is now.
Yad Vashem (the Holocaust museum in Israel) was founded in 1953 with the mission of commemorating and documenting what had occcured in the Holocaust. It's important to point out the work done by Rokhl Auerbakh, the director of Yad Vashem's Department for the Collection of Witness Testimony which was founded in 1954. Rokhl was a contributing member of the Oyneg Shabbos archive in the Warsaw Ghetto that recorded events in the ghetto as they were happening. Auerbakh valued recording events by those who lived them, and was doing so after the war. She helped gather witnesses to speak at the Eichmann trial, and she spoke at the trial as well.
So I would say that survivor accounts before the Eichmann trial were not too common, but there had been a movement to begin collecting them with the establishment of Yad Vashem and the work of Auerbakh, which began in 1953.
I could go on about the "Eichmann Effect" and how the trial was an impetus for the classic Holocaust survivor testimony, as we know of today, but you asked specifically about survivor testimony before the trial.
I know you posted this a bit ago, but feel free to ask any follow up questions and I'll do my best to answer them!
Sources:
- _URL_0_
- I saw the movie adaptation of Who Will Write Our History by Samuel Kassow and he did a Q/A session following the movie. Much of my basic info about Auerbakh comes from that conversation.
- _URL_1_
- I have worked with Holocaust survivor testimony professionally | [
"One of the goals of the trial was to disseminate information about the Holocaust to the public, and for the great majority of people around the world watching or reading about it, the Eichmann trial was their first confrontation with anything having to do with the Holocaust. As a result of all the coverage, it spa... |
the primary purpose of the supercomputer sequoia is nuclear weapons simulation. what does it mean? | They're simulating weapons to make sure they work so they don't have to physically test them. Those simulations are hard to do, and not always accurate if you don't have enough computing power. Nuclear physics is really complicated. | [
"The Advanced Simulation and Computing Program (or ASC) is a super-computing program run by the National Nuclear Security Administration, in order to simulate, test, and maintain the United States nuclear stockpile. The program was created in 1995 in order to support the Stockpile Stewardship Program (or SSP). The ... |
what part of a jet engine actually generates the thrust? | The gases being forced out the back are the source of thrust. It's actually different depending on what type of jet engines you're talking about.
Turbojet engines (all of the early jets, plus most older fighter jets) are all about the hot gases coming out from the turbines to provide thrust.
Turbofan engines (think airliners) on the other hand, actually generate the vast majority of their thrust from the cool air being blown back by the giant fan blades at the very front of the engine. A small part of the air gets sucked into the core of the engine, where it's compressed and burned to run the turbines, which in turn drive all the other components. This exhaust does provide some thrust as well. But most of the air (80% or more) bypasses the core entirely, providing thrust from the fan alone.
As for the turbines spinning? Jet engines are actually powered in reverse, sort of. The first 2/3 of the engine exists mostly to feed the rear 1/3 of the engine, and in turn the rear third actually provides the power to run the front third. That's all the turbines are there for, but it's the part that makes it all work.
Afterburners are a pretty simple concept, actually. They work by dumping huge amounts of raw jet fuel straight into the superheated exhaust gases, where they instantly ignite and provide even more thrust in the form of those awesome blazing exhaust flames. Basically, they turn the jet exhaust into a rocket engine of sorts. It consumes horrific amounts of fuel, but the sheer burst of power is worth it when a fighter really needs every last shred of power it can get. | [
"All jet engines are reaction engines that generate thrust by emitting a jet of fluid rearwards at relatively high speed. The forces on the inside of the engine needed to create this jet give a strong thrust on the engine which pushes the craft forwards.\n",
"The main fan on a jet engine consists of a number of a... |
Was there any damage to the Vatican City during WWII? | The Vatican was hit by bombs twice during the war, once in November of 1943 and again in March of 1944. The second bombing was done by an Italian plane, it killed one person and damaged the Pontifical Urban University and the Palace of the Holy Office with small bombs.
The 1943 bombing damaged the Vatican Gardens but caused no casualties. The supposition for years was that it was a lost American bomber. A 2010 book alleges that it was an attack on Vatican Radio made by fascist (and anticlerical) Italian forces. This book has not been reproduced in English, but there were contemporary rumors that an Italian plane was to blame. The RAF has also been blamed. The Vatican investigation into the bomb fragments yielded no clear culprit.
In any event, neither bombing caused major damage apart from the single death and another person wounded. It remains unclear whether the attacks were purposeful or accidental. | [
"BULLET::::- Despite its neutral status in World War II, Vatican City had four bombs dropped upon it from an unidentified airplane at 8:10 pm . Windows and glass were broken at St. Peter's Basilica and at the Palace of the Governorate, and there was damage to the Vatican aqueduct, but nobody was injured. A British ... |
Does a USB-C - USB-C charger extension cord slow down the charge? | First off, the battery charger is actually built into the phone. The wall wart is a constant voltage power supply. Some USB-C power supplies have the ability to output one of 2 or 3 different voltages, but they are voltage regulated.
All charging cables have resistance. Resistance causes voltage drop which reduces the energy delivered to a resistive load (see Ohms law). However, the charging circuit in the phone is a regulated supply so it can draw more current if the input voltage goes down. As long as the voltage does not drop below a certain threshold, an extension cable won't cause slow charging. If the voltage drop is above the threshold, charging will slow down, or even stop.
Edit: lithium cells are initially charged at constant current, then at constant voltage as the state of charge increases. The higher voltage from a USB-C power adapter allows higher wattage at lower current. It's like using high voltage for electric power transmission. The phone converts the voltage down to the cell's voltage. | [
"In addition to limiting the total average power used by the device, the USB specification limits the inrush current (i.e., the current used to charge decoupling and filter capacitors) when the device is first connected. Otherwise, connecting a device could cause problems with the host's internal power. USB devices... |
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