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For a typical box fan, does the air move because the blades "push" it or because of the Bernoulli Effect? | Fan blades work the same way screws work. As the blade turns about it's axis, the pitch of the blades forces air to move in the direction of the fan's axis (as well as spinning with the fan, but that's irrelevant here).
Bernoilli's principle is just a way of expressing conservation of energy in a flow of fluid, so it can be applied here, but it's not necessary to explain how fans generate thrust.
If you examine the shape of the fan blades, it should be apparent that angle of attack is the primary reason fans drive air forward. Airplane propellers use a more complex blade cross-section, more like a wing, which helps with efficiency, but angle of attack is a huge factor there as well - it's not just an airfoil moving at zero attack angle.
Also, the low pressure is on the back side of the blade, just as low pressure is on the top of the wing - it sounds like you may be a bit confused there. | [
"The air flows through the channel in the pedestal of the fan when the motor is turned on. After that, the air flows through the hollow tube. Then the air is shot out through 16-mm slits. This air flows smoothly, rather than turbulently as with a traditional fan (fan with blades). The curvature of the inner wall of... |
why does depression increase a lot when you happen to fall in love ? | From personal experience, depression seems to happen because the brain is focused on itself and it’s perception of itself from an outside perspective. Falling in love with someone is heavily emotional and depends largely on how the person you are in love with treats you. A depressed brain heavily relies on positive validation, as without it, it identifies a lack of interaction from others to that of worthlessness.
Another someone that you are in love with is more valuable to you than the ones you normally interact with on a daily basis. I myself can receive positive validation from others on a daily basis, but for me only the validation from the girl I love matters most and can lift me out of a funk. Unfortunately this girl I love lives very far from me and our communication has become difficult, making me feel depressed as although her perspective of me have not changed, her thoughts about me are not shared frequently.
Basically, the feedback you get from the one you love has a significant influence on your mental state due to the way you value their thoughts, moods, opinions, and perception of you. And the worst part is that you have no control over it, so if it’s not perfect then it can really be damaging to your mental health. I hope you don’t have the same experience I do where you are lost in hopeless love, and remember that you deserve to feel loved no matter what kind of person you think you are. No human life is undeserving of love!
This may not be easily understood by a 5-year old, but anyways I hope this helps! | [
"Depression can lead to a high increase of unemployment. It is more likely a balance sheet recession can cause depression. \"Due to falling asset prices and bank losses, this has a large impact on economic activity\".\n",
"In addition to the loss of a relationship with a loved one, conflict has also been suggeste... |
why is lemmy such a big deal? | First off, I hate Motorhead.
However, most metal fans and musicians loved the band. They had a unique sound forged in the early days of metal. Lemmy was the front man and only consistent member of the band. He was an icon.
Oh, and [Lemmy was God.](_URL_0_) | [
"Lemmy wanted the music to be \"fast and vicious, just like the MC5\". His stated aim was to \"concentrate on very basic music: loud, fast, city, raucous, arrogant, paranoid, speedfreak rock n roll ... it will be so loud that if we move in next door to you, your lawn will die\". He recruited guitarist Larry Wallis ... |
what effects do electronic devices, wi-fi, electromagnetic fields, etc. really have on human health? | To date, there is no proof that there is any effect whatsoever. Doesn't mean that it's impossible, though. | [
"Most studies have been unable to demonstrate any link to health effects, or have been inconclusive. Electromagnetic fields may have an effect on protein expression in laboratory settings but have not yet been demonstrated to have clinically significant effects in real-world settings. The World Health Organization ... |
the fda and its role in tobacco regulation | I'm not knowledgeable on this subject, but I think the ATF (Alcohol, Tobacco, Firearms) regulates tobacco, not the FDA. | [
"The FDA's authority to regulate came from the Food, Drug, and Cosmetic Act (FDCA). The FDA argued that nicotine was a \"drug\" and cigarettes and smokeless tobacco are \"devices\" that deliver nicotine to the body within the meaning of the FDCA. Congress had enacted a number of tobacco-specific laws after the FDCA... |
how can manure/hay self combust in hot temperatures even though they're nowhere near 200+ degrees celsius? | hay is more than just dried grass... it’s actually undergone a natural curing process which locks in nutrients and makes it keep better. This happens because grass doesn’t die the moment it’s been mowed...its cells (and certain microbes on it) continue to respire, and this creates some heat.
now imagine this grass is a little bit damp... it gets made into hay bales and theyre stacked sky-high in a sealed barn. the middle of each bale has little chance to cool down (low air flow) and the cellular respiration... and maybe even now some fermentation... go on and on. this is like having a pile of oily rags in a hot room. the temperature inside the bale can climb to the tipping point where it starts smoldering. nobody notices. it’s packed can’t-reach-it deep in a barn full of fuel. ay yi yi. | [
"Hay baled before it is fully dry can produce enough heat to start a fire. Haystacks produce internal heat due to bacterial fermentation. If hay is stacked with wet grass, the heat produced can be sufficient to ignite the hay causing a fire. Farmers have to be careful about moisture levels to avoid spontaneous comb... |
i have acid reflux. what is happening inside of my body that makes it feel like i am softly belching molten lava? | You are burping up a strong stomach acid and while your stomach has a protective lining, your throath has not.
The acid is corroding your throath and that feels like belching molten lava. | [
"During an episode of acid reflux, small amounts of stomach acid may manage to escape from the stomach and into the oesophagus. Typically, gravity minimises this upward leakage but combining an inversion table and acid reflux can be a painful, nauseating, and potentially dangerous combination.\n",
"This stage is ... |
Physiology Blood type question, how can universal recipient receive any type of blood and universal donor can donate to any blood type without the transfused blood cells being attacked and destroyed? | Blood type describes the type of antigens (structures used in immune system response) found on a person’s red blood cells. The letters (A, B, & O) refer to sugar-based antigens. There are A antigens and B antigens. We use type O to refer to blood cells with neither A or B antigens. The plus/minus (Rh D) refers to a protein-based antigen. Plus blood types have the Rh D antigen, while minus types do not have it.
The immune system recognizes antigens as either native or foreign to the body. Any blood cells with foreign antigens will be attacked by the immune system; this is why blood types must be taken into account for blood transfusions. Red blood cells without these antigens will be accepted by any immune system. This is why O- is the universal donor; it does not have the A, B, or Rh D antigens, allowing it to avoid detection. In contrast AB+ is the universal recipient; it has all 3 antigens and therefore the immune system will be accepting of any blood type.
As a quick example, we can think about a type A- person (only have the A antigen) donating to our universal donor (O-) and our universal recipient (AB+). The universal recipient has A antigens in its blood already. So the universal recipient’s immune system is accepting of the A- blood. On the other hand, the universal donor does not have A antigens in its blood. So the universal donor’s immune system will attack the type A red blood cells. This will cause a transfusion reaction which can range from mild to life-threatening.
[Source 1]( _URL_0_), [Source 2]( _URL_1_) | [
"The donor's blood type must be determined if the blood will be used for transfusions. The collecting agency usually identifies whether the blood is type A, B, AB, or O and the donor's Rh (D) type and will screen for antibodies to less common antigens. More testing, including a crossmatch, is usually done before a ... |
What would happen if a soldier in the U.S. military from the south, was stationed in the north during the start of the civil war, but he support the confederacy and wanted to go fight for them? Would he be arrested or allowed to leave? | Fun fact, only officers really defected to the Confederacy. I am aware of no rank and file soldier defecting after secession, and even if one or two did, there was no mass exodus out of the Regular Army.
Thats important, because Officers were held to a different standard. Firstly, many of the men who became prominent officers during the war were civilians during the secession movement. Obviously, in that weird political limbo, it was pretty easy to slip away to their state of choice. But for active officers even, there was a different code of "honor", and many of these men knew each other socially. Its not like today, where tens of thousands of officers served in active duty in the Army. With a small army, the officer corps naturally grew intimate in a way were not familiar with. And when your friend, a drinking buddy, a West Point classmate, a social acquaintance said they were heading south, it was a lot harder to arrest them for treason. | [
"Hylan Benton Lyon (February 22, 1836 – April 25, 1907) was a career officer in the United States Army until the start of the American Civil War, when he resigned rather than fight against the South. As a Confederate brigadier general, he led a daring cavalry raid into Kentucky in December 1864, in which his troops... |
what is the difference between a president, a chancellor, and a prime minister? | It varies from nation to nation. In general, many nations have both a head of government and a head of state.
In the Westminster system (UK, Canada, Australia), the Prime Minister is the head of the government and is in charge of all executive policy. The prime minister and other government ministers are also often, but not always, sitting members of the legislature. The head of state is largely a cerimonial role, often filled by a king, queen, or governor general.
In the United States of America, the president is the head of state and the head of the government's executive branch. However, the USA observes strict separation between the executive branch and the legislature. The president does not sit in the house, cannot vote on legislation (although he or she must either veto it or sign it into law), and cannot whip his or her party. However, the Vice President does have a tie-breaking role in the Senate.
In countries that have both a President and a Prime Minister, the President is the head of state and the Prime Minister is the head of government. What duties belong to whom varies from country to country however it is common for the President to handle foreign affairs, non-political affairs, and exercise discretionary reserve powers.
Chancellor is a title in Germany that is equivalent to Prime Minister. | [
"The Chancellor is the head of government and the most influential figure in German day-to-day politics, as well as the head of the Federal Cabinet, consisting of ministers appointed by the Federal President on the Chancellor's suggestion. While every minister governs his or her department autonomously, the Chancel... |
why are there so many fake movie trailers trending on youtube? | Majority of them are getting tricked, it's like people watching those GTA 6 videos. The people posting them do it on purpose for views, this one guy had practically made a living by making videos like "Rockstar accidentally sent me GTA 6!" If you throw some ads on you can make some pretty easy money | [
"Over the years, there have been many instances where trailers give misleading representations of their films. They may give the impression that a celebrity who only has a minor part in the film is one of the main cast members, or advertising a film as being more action-packed than it is. These tricks are usually d... |
What was life like in Rome's provinces? How different would life be in a province compared to Rome itself? | This is a very, very vast and complicated question. Not only does the meaning of what a province actually *is* change considerably over the course of Roman history, but the provinces themselves have an internal history and considerable variation, from Britannia to Egypt or Baetica to Syria. There can be more variation in a provicne itself than between Rome and a province, meaning, life in Augusta Treverorum/Trier in the 3rd/4th century would be more similar to life in Rome than to life in a small village 10 km away, or a villa rustica outside the gates of the citry.
If you could narrow it down to an area or time-frame that interests you, that would be very helpful since otherwise this is just too vast a question to answer easily (to give you an idea consider a modern analogy - switch provinces with U.S. states and Rome with Washington, even if it's a poor analogy - and try to answer that question over only some 300 years of history). | [
"Each Roman province comprised a number of communities of different status. Alongside Roman colonies or \"municipia\", whose residents held the Roman citizenship or Latin citizenship, a province was largely formed by self-governing communities of natives (\"peregrini\"), which were distinguished according to the le... |
why does gravity influence objects with larger mass, even though they're farther away, more than those with smaller mass | The thing with space station is not that they're so far away or anything. If you build a tower as high as to reach ISS, you would experience about 90% of normal surface gravity on top of that building. You would not float, things would fall down almost as fast as on Earth.
The difference is that on ISS, people are on free fall. That's what makes weightlessness happen. In fact, that's how you train astronauts for weightlessness as well, you climb high up with aeroplane, and then just dive at free fall speed for as long as possible. People inside remain weightless until plane has to stop dive to avoid crashing.
ISS however is not gonna crash. Orbiting basically happens when you're moving sideways fast enough that on free fall you miss the Earth. That means everyone will remain weightless there.
The moon orbits Earth just the same, it falls towards Earth but keeps missing because of sideways motion | [
"The distinction between mass and weight is unimportant for many practical purposes because the strength of gravity does not vary too much on the surface of the Earth. In a uniform gravitational field, the gravitational force exerted on an object (its weight) is directly proportional to its mass. For example, objec... |
what are the differences between the electricity in the usa vs. europe. | Europe uses a 220 volt system, whereas the United States uses a 110 volt system. The 220 volt system is just more powerful, but can also be more dangerous if you are shocked by it. | [
"As a whole, the European Union currently generates 11% of its electricity using cogeneration, saving Europe an estimated 35 Mtoe per annum. However, there are large differences between the member states, with energy savings ranging from 2% to 60%. Europe has the three countries with the world's most intensive coge... |
how are new data points created in a video such that a video filmed in 30 fps can be viewed at 60 fps? | Interpolation is a process where a display unit (TV/Monitor) takes two frames and puts them together (similar to an "average") to generate an extra frame in the middle. By inserting an extra frame between each one that was recorded, you effectively double the frames per second and can bring 30 to 60. | [
"Some teams use digital video cameras to record the pass, and then review frame-by-frame to develop an estimate of distance, but the traditional frame rate of 30 frames per second (FPS) can present a problem in that it is unlikely to capture a frame of the exact moment the returning dog breaches the plane of the st... |
If a Tsunami is coming inland would it be better to attempt to go upward into skyscraper, or try to go inland? | That depends on your location on the beach, the structural integrity of the beach-side buildings and the size of the tsunami.
Most tsunami travel a fairly short distance once beached, think of how quickly a big wave stops when walking on sand. The flooding can reach 300 meters or more from the coastline, the average human can sprint this distance in 30 seconds to a minute so this is likely your best bet.
If you heppen to be in a skyscapper near the beach when a tsunami hits, you are likely safe (or really, really not safe; depends on the engineers who built it).
Otherwise it is probably not worthwhile to try to cram into one, as it will wase time you could spend running. Just make sure you don't get stuck in the horde and evacuate as soon as you hear a tsunami warning. If you can see the wave and are not in safe high groung, you are doing it wrong.
Also, mabe don't go to the beach after an earthquake.
| [
"Tsunamis, potentially enormous waves often caused by earthquakes, have great erosional and sediment-reworking potential. They may strip beaches of sand that may have taken years to accumulate and may destroy trees and other coastal vegetation. Tsunamis are also capable of flooding hundreds of meters inland past th... |
richard the lionheart. how did brits know what lions were if at that point they had never been to africa? | > If Brits didn't go to Africa until like the 17/1800s, why did they call Richard the first Richard the lionheart?
Here's your problem - this is untrue. It's true that there was less travel back then... but there was travel. Don't forget the Crusades were on during this time... which I believe is where Richard earned that moniker.
The English (calling them Brits is just incorrect historically) knew about lions. | [
"British Lions were a short-lived British rock band, together from 1977 to 1980, with former members of Mott and Medicine Head. They released just two studio albums with little commercial success in the UK.\n",
"The British Lions toured South Africa a number of times. Despite officially being South African tours,... |
Historic Document Translation? | You are correct, it means 'ditto'
It shows up very commonly in passenger and freight manifests for ships. Other things said would be 'same', 'above', 'SAA', a single or double quotation mark or a carrot.
Source: Pg 4, [Immigration Research Guide from _URL_0_](_URL_1_)
| [
"Translation history concerns the history of translators as a professional and social group, as well as the history of translations as indicators of the way cultures develop, interact, and may die. Some principles for translation history have been proposed by Lieven D'hulst and Pym. Major projects in translation hi... |
why do so many apps require sign-up these days? | They require this information so they or their partners can send you marketing information based on what you so on you phone, where you are, what time it is, etc. If you want to use these apps most of the time you don't have a choice. Some of the app owners may also sell on the information they gather from you. | [
"A new single sign-on implementation known as \"Sign in with Apple\" was implemented, allowing users to create accounts with third-party services with a minimal amount of information. Users have the option to generate a disposable email address for each site, improving privacy, anonymity, and further reduces the am... |
Why were there so many different names for the ancient greeks? Lacedemonians, hellenes, etc... | In the Classical period, there is only one name for the Greeks: *hoi Hellênes*, the people of Hellas.
There were, however, numerous ways to refer to the Greeks in earlier times. In the works of Homer, the most common name for the Greeks is *hoi Akhaioi*, the Achaeans; this may have been an archaising way to refer to the Greeks, which originally dates back to the Mycenaean period. In Classical times, the name referred only to the people of Achaea, an unremarkable region in the north of the Peloponnese.
Additional names found in the Iliad and Odyssey are *hoi Danaoi*, the Danaans, and *hoi Argeioi*, the Argives. Like "Achaeans", the latter is a *pars pro toto* elision - the name of one part is used as a name for the whole. The city of Argos was one of the largest and most prominent cities in mainland Greece, and so its people were apparently used as a shorthand to mean all the Greeks.
None of the Homeric names remained in widespread use. For most of Antiquity, the standard Greek name for the Greeks was *hoi Hellênes*. However, the Greek world consisted of many hundreds of smaller states, regions, and dialect groups, all of which had their own names (and sometimes several names). Your example, "Lacedaemonians", does not mean "the Greeks" as a whole - it is the name for the inhabitants of Lacedaemon, a region in the southeastern Peloponnese of which the main urban centre was the town of Sparta.
There are certainly many names for the full citizens of Sparta. As citizens they were known as Equals and as Spartiates; as inhabitants of their region they were called Spartans and Laconians and Lacedaemonians; as speakers of Doric Greek, they were called Dorians; and finally, as inhabitants of Hellas, they were called Hellenes. But only that final word described the ancient Greeks as a whole. | [
"In the classical period, the generic term for Greeks was \"Hellenes\", echoing the Hesiodic foundation story in which Hellen was the founder of the Greek race. However, in the \"Iliad\", \"Hellenes\" is restricted to those inhabitants of \"Hellas\", a region in Thessaly. There were therefore at least two different... |
Why don't Americans eat very much sheep? | Hi, not discouraging further contributions here, but you may be interested in some previous threads on sheep in the USA
* [If sheep were so numerous and popular in medieval times, why do we use so few sheep products now? What happened to the sheep?](_URL_0_), with a few follow-on comments here [Why do I not eat mutton?](_URL_2_)
* [Why/how did North Americans stop eating lamb in favour of other meats?](_URL_1_) | [
"Since the 1960s, per capita consumption of lamb and mutton declined from nearly 5 pounds to just about 1 pound, due to competition from poultry, pork, beef, and other meats. Since the 1990s, U.S. sheep operations declined from around 105,000 to around 80,000 due to shrinking revenues and low rates of return. Accor... |
how was the chris hanson predator show not entrapment? | Entrapment involves inducing someone to commit a crime they otherwise would not be inclined to carry out. For example threatening someone to get them to buy drugs. However posing as a drug dealer and arresting those attempting to buy drugs is not entrapment, as people not inclined to illegally purchase drugs would not do so even if the opportunity was presented by the undercover officer.
In the case of To Catch a Predator the police were simply posing as underage children. Someone who was not a pedophile wouldn't be caught up in such an act, so it isn't entrapment. | [
"On 5 September 1997, the Court of Appeal gave Howard Hughes leave to appeal against his conviction for the abduction, rape and murder of Sophie Hook. Six months later he sparked further outrage by launching a £50,000 compensation claim against the Bryn Estyn children's home, where he claimed he was abused as a chi... |
why does reddit have such a bad reputation amongst non-redditors | a lot of the big things reddit gets known for (the events that blow up) paint reddit in a bad light. The most popular probably is the witch hunt on the wrong guy for the Boston bombings, which made reddit look extremely racist. The other is the nazi flag on the front page (which is still the 6th most upvoted thing of all time) which..i mean you can see how that looks. And the other big one is the massive outpouring of anti-fat hatred and anti-woman hatred during the ellen pao fiasco | [
"Reddit's users tend to be more privacy-conscious than on other websites, often using tools like AdBlock and proxies, and they dislike \"feeling manipulated by brands\" but respond well to \"content that begs for intelligent viewers and participants.\" Lauren Orsini writes in ReadWrite that \"Reddit's huge communit... |
what action could navient take if all borrowers stopped paying our student loans? | I am sure there would be instant penalties for late payment. The borrowers would eventually have to pay extra interest. The debts are legal. Their manner of operation was not fair. If all the borrowers stopped paying the worth of the company would increase due to expected increased future revenue.
The company is good at collecting debt owed. They would just do it efficiently and make more money. | [
"Defaulting on student loans can also end in a lawsuit. The government and private lenders can sue in order to collect on loans. There is no time limit on suing to collect on federal student loans, and the borrower can be sued indefinitely. Private student loans, in most cases, are subject to statute of limitations... |
Hello. I would like to expand my knowledge about the general history of Europe | Hi! Glad you're taking an interest in history. SO, you like Europe but don't know where to start. I'll give you a good list to get started but we have to cover two things first: Historical Interpretation and Historiography.
History isn't an exact retelling of the past, instead, it is an argument about the past; this is because we only have a certain number of sources and they don't all line up perfectly and they are all biased. Therefore the historian's job is to take a look at these sources and compare them to one another and tease out the truth as best as possible. The facts and truths are just that--facts and truths--they don't mean anything on their own. Julius Caesar is assassinated in 44 BCE. Big deal. What does it mean? This what the historian tries to explain! After uncovering facts and truths from the sources, these are then lined up into a narrative of whatever event they are studying, and in the process of creating a narrative, the historian interprets the facts in a way that makes sense.
In the process of interpretation, the historian has an argument about the past they are trying to make: Edward Gibbon looked at the third through sixth centuries and to him, the facts made it evident that Rome was collapsing. Therefore this is what stands out to him and this what he writes about. Peter Brown took another look at it and while he saw decay, he also saw growth, so that is the argument he made.
There are all of these different arguments, and that is what history is characterized by--this isn't something fully touched on in school until the college level. As more evidence and sources are uncovered these arguments and views change over time. To re-use my previous example, the standard view of what happened to the Roman Empire--that it declined and fell in fire and blood and war and whatnot--comes from Edward Gibbon's work The Decline and Fall of the Roman Empire because this was what the evidence available at the time (1700s) led him to believe. More evidence is uncovered and debates move forward until, in 1971, Peter Brown writes The World of Late Antiquity, which challenges the notion of a decline and fall, and which emphasized the cultural legacy of Rome and revitalization of Europe in that era.
These arguments and the state of the field of history is something called Historiography: how historians have seen a certain event or era over time, as well the general written body of works on a given topic (anything written on the Roman Empire is part of Roman Historiography, for example).
Now that that's out of the way I'll give you a list of works, and I'll explain how to read the works like a historian! | [
"BULLET::::- The Reconstruction of Europe: A Sketch of the Diplomatic and Military History of Continental Europe, from the Rise to the Fall of the Second French Empire by Harold Murdock, John Fiske; Houghton, Mifflin and Company, 1889\n",
"BULLET::::- Robinson, James Harvey, and Charles Austin Beard. \"Readings i... |
how old is the notion of the political party? | Many of the answers that have been given focus on the machinery of the modern political party, but the question is about the *notion* of the political party, which is rather different. As with many of the central ideas of modern liberal-democratic politics, this concept can be traced, broadly speaking, to 17th and 18th-century England. It's no surprise that David Hume, writing in the mid-18th century, comments on the novelty of the concept, listing beside "factions of interest" and "affection" the "parties from principle":
> Parties from principle, especially abstract speculative principle, are known only to modern times, and are, perhaps, the most extraordinary and unaccountable phænomenon, that has yet appeared in human affairs. [[Source](_URL_0_)]
Henry Bolingbroke was instrumental in formulating the idea, being one of the first figures to argue for the need for a systematic opposition. In his *On the Idea of a Patriot King*, Bolingbroke argued for a formal opposition party to scrutinise and oppose government policies. He used this argument to support the unity of the so-called "Country Party", a coalition that was formed to oppose the government at the time.
By the time of Edmund Burke in the later 18th century, the idea of the party had been firmly established: "a body of men united ... upon some particular principle".
This idea is closely linked to, and to a large extent enabled by, the development of British liberalism. The Enlightenment liberals essentially upheld the idea that it was possible to reasonably disagree on the common good -- this was rather in contrast to many previous arguments which had seen the definition of the common good as an inherent function of sovereignty (Hobbes, for instance, thought along these lines). On this basis it was possible to articulate the idea of factions of people united not because of venal interest or obligations, but because of their principled agreement on some particular issue.
It is interesting that in more recent history the idea of the party has swung back in the opposite direction, becoming seen not as a mechanism for legitimate disagreement but, as Hume would put it, a "faction of interest" (Marx, of course, was instrumental in triggering this change with his reduction of all political discourse to an economic 'base'). | [
"The First Party System is a model of American politics used in history and political science to periodize the political party system that existed in the United States between roughly 1792 and 1824. It featured two national parties competing for control of the presidency, Congress, and the states: the Federalist Pa... |
Why did the pikemen of the Hellenistic phalanxes carry shields, while the medieval European pikemen didn't? | I don't know a ton about ancient pikemen, but as for the Swiss:
The massive pikes they used required two hands to use effectively, but that still could have allowed the use of a small shield. The Swiss pike formation adopted very aggressive tactics - the goal was to use a combination of speed, surprise, and shock to overrun the enemy force before they knew what hit them. Still, this doesn't necessarily preclude the use of a small shield.
I think a better answer would note that shields in general were in decline in European warfare at this time, or at least radical transformation when it came to their traditional function. First, the introduction of steel plate armor made shields increasingly redundant, as anything capable of getting through your breastplate would probably pierce a shield. Men-at-arms began to use two-handed weapons almost exclusively, and shields like the buckler became more associated with light armor. Second, the increasing use of firearms made the anti-archery function of shields less useful and prompted a focus on thick armor to deflect bullets over large shields to catch arrows.
So, in the time that the pike were rising (mid 15th to early 16th centuries) shields were on their way out due to better armor and a change in the likely threat from ranged attacks. The pikemen of the era wore plate corselets (and possibly more, up to three quarters or full plate armor if they could get it) to defend themselves, which provided more protection than shields were likely too against gunfire and enemy blades and gave them good protection while keeping their hands free.
Note that this is simplified - this is also the era of the buckler and Spanish "sword and buckler men" (who, despite the name, used full shields rather than bucklers). But the shields of that time focused more on complementing a maneuverable soldier who could use it in melee against a close-quarters opponent - not exactly a situation a pikeman is likely to find himself in.
Interested in anyone's comments, especially someone familiar with Hellenistic phalanxes - I'd love to compare and contrast. | [
"Such deep pike columns could crush lesser infantry in close combat and were invulnerable to the effects of a cavalry charge, but they were vulnerable to firearms if they could be immobilized (as seen in the Battle of Marignano). The Swiss mercenaries did deploy bows, crossbows, handguns and artillery of their own,... |
Who is the current "Lineal Champion" of military history? | I don't think this is answerable (even if it didn't break the rules).
The greatest military minds in history are by definition generals who performed exceptionally well. They won wars after wars, beat all those around them, and by these feats are labelled as exceptional military leaders. In this sense they are considered exceptional military minds because they are the champions of their place and time.
That means there's no way to have a show down between these metaphorical champions. Alexander the Great, Bai Qi, Caesar, Ashoka, Napoleon, Uesugi Kenshin, Genghis Khan and a whole bunch of talented generals and admirals did not fight each other. They existed at different times and/or places. So there is simply no way to answer your question. | [
"Among memorable field leaders of the army were Nathaniel Lyon (first Union general to be killed in battle during the war), William Rosecrans, George Henry Thomas and William Tecumseh Sherman. Others, of lesser competence, included Benjamin F. Butler.\n",
"By some historians he is considered the most effective ge... |
why does the federal reserve pay interest to banks? what is the impact of this? | It's the other way around: the banks pay interest to the Federal Reserve Bank on money they borrow from the FRB.
A higher rate on those loans makes it more expensive for banks to borrow money, which makes those banks charge more for loans (discouraging borrowers) or be more cautious about the loans they make. | [
"The United States Federal Reserve System lends money to eligible commercial institution called discount window, Purposely created in 1913 as a mean to operate the central bank in The United States. The interest on loans given out to commercial institutions are discount rate, which is a monetary policy tool used by... |
Why is Hitler's Muder of USSR Civilians never talked about? | [This thread](_URL_1_) from /u/commiespaceinvader discusses Generalplan Ost, which is the larger planned campaign of murder in the East, beyond simply the Holocaust. It doesn't specifically address "why is it never talked about" in the way you might be wondering, but I would caution you about *any* question which is premised in that way, as the answer is rarely one that can be approached entirely objectively, as it, in reality, says more about where and when you were in school, and what kind of media you generally have been exposed to, so the answer can vary wildly for, say, someone with a basic high school education who graduated in 1960, and someone like this /u/Georgy_K_Zhukov guy who has read extensively about the Eastern Front of World War II. [This answer I wrote a little while ago](_URL_0_) is *not* about Generalplan Ost, but it is about another topic on the Eastern Front, and I think is relevant for you here. The sum which carries over is that, while Generalplan Ost *is* a bigger deal than the Night Witches, it still is something which brief coverage - if any - is the best I would expect to see in a high school environment, and given how cursory education of even the Holocaust often is at that level (I'm failing to find it, but there have been some useful discussion chains between myself, /u/kugelfang52, and several others, about the poor quality of Holocaust education in the American school system, which perhaps he can remember the thread for), skipping over it is not at all surprising. | [
"In the Soviet occupation zone, members of the SED reported to Stalin that looting and rape by Soviet soldiers could result in a negative reaction by the German population towards the Soviet Union and the future of socialism in East Germany. Stalin is said to have angrily reacted: \"I shall not tolerate anybody dra... |
Is the optic nerve stretchy or is there some slack to let your eye move? | The optic nerve in an adult has about 8mm of slack to allow the eye to move.
Nerves in general do not stretch very much, and the optic nerve in particular cannot stretch at all. That's because it is part of the central nervous system.
Because the nerve connects directly to the brain, it is covered in an extension of the brain's protective membrane envelope. Those membranes are called the "meninges," and consist of three layers: the dura, the arachnoid, and the pia mater. The dura is the outermost layer. It's relatively thick and consists of tough, fibrous, connective tissue, to protect the other membrane layers and the underlying nerve itself. It doesn't stretch significantly, and that means the whole bundle has to stay a pretty much constant length. | [
"The nerve enters the deep surface of the muscle and is not easily visualised and differentiated from other structures running with it, such as the blood vessels. Parting the muscle damages the nerve further by stretching or even rupturing its branches which run superiorly on its deep surface.\n",
"When a muscle ... |
Would inhabitants of the ISS be able to see with their bare eyes if a nuclear war started on earth? | oh yeah, no doubt they could see it and the fires burning after..
talking about things which explode brighter than the sun..
ISS is only 350 kilometers up or so.. not very far
| [
"Speaking at the plenary meeting of the Parliamentary Assembly of the Organization for Security and Co-operation in Europe on 8 July 2019, she stated that “On the board of the International Space Station, [she and other astronauts] had a chance to see with naked eyes how bombs and shells exploded in Donbass and Luh... |
How does your brain know how to assemble the signals from the individual cells in your retina into a spatial image? | It is both hard-wired and partly plastic.
The basic organization is hard-wired, particularly in the crossing of some neurons from the right eye to the left side of the brain and some neurons from the left eye to the right side of the brain (while some from the right eye stay on the same side of the brain, and the same for the left!). The visual field is broken down into small areas and organized in a visuotopic map in the primary visual cortex, by which a particular area of the visual field is always handled by the same area of the brain. A great deal of this is organized based on orientation - close areas of the visual field are represented nearby in the visual cortex. These areas in the visual cortex are organized into columns in the outside layer of the brain, the gray matter, in the occipital lobe.
But there are some complications. For instance, much of the visual field can be seen with both eyes simultaneously. In these instances, the two areas of the retina corresponding to a particular point in the visual field - one from each eye - are mapped to adjacent areas in the visual cortex. So you have patterns of columns that are organized so that the areas of the visual field are mapped to columns that are adjacent to each other or very nearby.
But this basic organization is also somewhat plastic - it can be changed, particularly if there is a problem with the eyes at a very young age. If one eye is faulty or destroyed very early in life, we see that the columns of the visual cortex for the normal eye will expand, "eating into" the areas for the damaged eye (which are not receiving meaningful input). The later in life this happens, the less the brain is able to repurpose the unused portions of the visual cortex.
Edit: But despite all this hard-wiring, the human brain can, amazingly, adapt to functioning in a world that is completely inverted, for instance, even if the inversion happens well into adulthood. All day, every day, George Stratton wore glasses that inverted the world - everything was upside down. By the 5th day, the inverted images appeared to be upright to him, and it was only when he concentrated that he was able to tell that they were inverted. His brain had seemingly reorganized its interpretation of the visual field to account for the change in orientation so that his mental image _seemed_ correct, even though it was inverted relative to the normal way light waves strike the retina. | [
"Eventually, the information these cells collect in the retina is sent to various parts of the visual cortex, including the posterior parietal cortex and area V5 through the dorsal stream, and the inferior temporal cortex and area V4 through the ventral stream.\n",
"When a visual stimulus is seen before a saccade... |
Did any countries in the Middle East play any roll in WWI or WWII? If so, what? | There were a number of allied invasions in the region during 1941, as Britain pre-emptively dealt with potential threats to their oil supplies and lines of communications. At the time, the British position in North Africa was looking somewhat dire, as German forces under Rommel started to advance into Egypt itself.
Iran (formerly Persia) was occupied by Britain and the USSR from 1941 through the end of the war, and the Shah was forced to abdicate in favour of his son. Iraq was also invaded by Britain in 1941 after a military coup there lead the British to worry about the safety of the oil supply. During that conflict, German and Italian aircraft were given permission to aid Iraq by staging through the Vichy French territories of Lebanon and Syria, leading to an allied invasion of those two.
[edit] I missed the fact that you were also asking about WWI. My mistake. As others have already covered that, I'll leave it at that. | [
"The premise of the game is a prophecy by Nostradamus that at the end of the 20th century there would be a major world war, beginning somewhere in the Middle East. The game was produced at a time of escalating violence in the Persian Gulf due to the Iran–Iraq War.\n",
"The Middle Eastern theatre of World War I sa... |
why is everyone blaming the current ad revenue problems on youtube on youtube itself? | It's a very complicated subject to be honest.
Youtube is responsible to where those ads will be put on. If an ad is put on a video promoting violence, then it's the responsibility of youtube. The advertisers had confidence in youtube that their ads won't be used on inappropriate video.
That said. There is a lot going on behind the curtain and everybody want to take advantage of the situation. Basically, youtube have blood in the sea and a lot of shark are going after it now.
Conventional media : They are losing audience and ad revenue because of youtube. Hurting youtube credibility and advertiser will spend the money they use to spend on youtube in other platform like in conventional media. So those media are putting more attention against youtube, even changing facts of some story to fit their agenda.
Media Advertiser and competition of youtube : The first and biggers advertiser to stop using youtube are media telecom. Compagnies like AT & T, Verizon, etc. Those company are competitor to youtube. Those own media company like HBO, TNT, TBS, Warner bros, CNN. Right now, those company need to put add on youtube if they want to reach a larger public. But if they hurt enough youtube, their own company could take the place of youtube.
I also heard of Eric Feinberg. Some people think that he have a big part to play into all of this. He believe that the only way youtube can fix the problem is with AI to identify video that shouldn't get ads on, but he also believe that youtube can't achieve that would either violating his patent in AI technology or buying the AI product from his own company. He made several media appearance that started this whole thing.
Basically, youtube have problems controlling on which video ads go so there is some situation where ads go in inappropriate video. That should be negotiate between youtube and their clients, but a lot of actors have to gain with this so they go public with it and embellish the situation so much that now advertiser without anything to gain in this are forced to remove their ads from youtube because they fear for their public image. | [
"Advertising is YouTube's central mechanism for gaining revenue. This issue has also been taken up in scientific analysis. Don Tapscott and Anthony D. Williams argue in their book \"Wikinomics\" that YouTube is an example for an economy that is based on mass collaboration and makes use of the Internet.\n",
"In Ma... |
how can a [computer] screen keep track of each and every pixel? how can it be this specific? | The idea, or perhaps model, is that every pixel on your screen can be identified with its own address. For pixels, addresses are usually in the form of coordinates. A bit (or a lot) as how points are identified in a mathematical graph.
It is customary to assign one of the four corners of your screen device the coordinates (x=0, y=0) and address all other pixels on your screen relative to that. Let us assume that the lower left corner is (0,0) and your screen resolution is x*y = 1080*1920. A point somewhere near the middle of your screen would have coordinates (x=539, y=959).
So far, all the coordinates I spoke of are *physical* coordinates. You can take a ruler to your display device, and provided it has a proper scale, use it to identify the individual pixels.
Now, the software that is responsible for rendering an image on your display device has a region of computer memory dedicated to mirror the actual physical pixels of your display device.
Let us say your program wants the pixel at coordinate (33, 22) set to an intense red. It instructs the *driver* (the bit of program that actually controls your display device) to set a certain value in a certain memory location. The value being "intense red" and the memory location coresponding to the pixel located at (33,22) on your display device.
This is how things are aranged on the threshold between your program and the driver for your display device.
Now, how does the driver drive the display device? Here we enter into the realm of hardware. Physically, the pixels in colour displays have three distinct settings, being the amount of red, blue and green light they emit. By varying the relative amounts of these three primary colours, you can pretty much create the illusion of any other colour. At least good enough to fool a human eye.
So what the driver program does to drive the display hardware is it says "for the pixel at (33,22) I want the settings to be 80% green, 4% blue and 76% red".
*How* exactly the driver program manages to convey this message to the display device is a whole different kind of magic. The ususal scheme is that you send the information from the driver program to the display device at a pace that is fixed in time. So at 0.01 milliseconds you send the info for pixel (x=0, y=0) and at 0.02 milliseconds you send the info for the next pixel at (x=0, y=1).
Clearly, the driver program and the display device somehow must agree on when the sequence starts, so that both understand that a certain set of (red green blue) values is meant for a certain physical pixel. Rather than having each computer and/or display device manufacturer think up their own original way of getting synchronized, industry standards have been layed down.
Also, sending data to be displayed on a device is not a static activity. When you are watching a video, movie or playing a game, you expect what you see to change from moment to moment. This is accomplished by continuously updating the information sent from the driver program to the display device. In general, the speed and smoothness that this happens with is refferred to as "frames per second".
| [
"When a single column of 24 pixels is scanned across a line of text, all of the information is acquired. However, with the sense of touch, people are capable of perceiving two dimensional images. Bliss wondered if the reading rate would be higher if more than one column of 24 pixels were used, and if so, how many c... |
how do refrigerants like hfcs and hfos work? | The way they absorb heat to act as greenhouse gases (absorption of infrared radiation) and the way they absorb heat to act as refrigerants (phase change at convenient temperatures and pressures) are unrelated to each other. They don't correlate because there is no reason for them to correlate.
Many substances are good at absorbing heat during phase changes. But most of them do so at temperatures or pressures which aren't practical to use in everyday refrigeration. Or, they are toxic, explosive, or corrosive. | [
"Vapor-compression refrigeration or vapor-compression refrigeration system (VCRS), in which the refrigerant undergoes phase changes, is one of the many refrigeration cycles and is the most widely used method for air-conditioning of buildings and automobiles. It is also used in domestic and commercial refrigerators,... |
what is the difference between weapons grade and non-weapons grade nuclear material? | Weapons grade fuels have high enrichment, power-grade fuels are low enrichment.
Enrichment is what % of the nuclear material is capable of a chain reaction on its own. Power reactor fuel is < 5% Uranium-235 or Plutonium-239. The other 95% is a filler material.
Weapons grade fuel is > 90% Uranium-235 or Plutonium-239.
If the enrichment is low ( < 10%) it is virtually impossible to make a nuclear bomb, because there's just not enough fuel there to do it. But it does a hell of a good job boiling water. | [
"Weapons-grade nuclear material is any fissionable nuclear material that is pure enough to make a nuclear weapon or has properties that make it particularly suitable for nuclear weapons use. Plutonium and uranium in grades normally used in nuclear weapons are the most common examples. (These nuclear materials have ... |
If all ship's radars operate on the same frequency (S & X band), why don't they interfere with one another? | They generally would. Though specific bands are rather large, antennas/radars can operate in narrow frequency ranges within a band, and the frequency space required to prevent interference between two bands can be, by design, very narrow (you could have a radar operating at 9.985 GHz and another at 9.920 GHz). The amount of received power drops off dramatically as the received frequency deviates from an antenna's designed frequency.
Further, antennas on radars are frequently highly directional, both focusing energy emitted in one direction and highly attenuating energy received from directions other than the intended receiving direction.
Further, advanced radars can encode their transmissions using algorithms such as Binary Phase Shift Keying. This allows the receiver to filter out noise from its own signals. | [
"Frequency agile radars can offer the same advantages. In the case of several aircraft operating in the same location, the radars can select frequencies that are not being used in order to avoid interference. This is not as simple as the case of a cell phone, however, because ideally the radars would change their o... |
how all the counting numbers can be interesting at once | Well, you've simply created a paradox for yourself. By defining 'the first boring' as 'interesting' you've created an unbreakable loop, where your two classifications refute one another.
If it's the first boring number, it's not interesting. But if that makes it interesting, it's not the first boring number. | [
"If the number of counts is not very large, it is more accurate to measure the time interval for a predetermined number of occurrences, rather than the number of occurrences within a specified time. The latter method introduces a random error into the count of between zero and one count, so on average half a count.... |
A couple of rudimentary physics questions my teachers never could really answer, for some reason or another, that I'd like to still know. [Big post warning] | 1) Light has no *rest* mass but has momentum based on it's frequency. Newton's laws don't describe it as it wasn't discovered yet. Newtonian laws only apply to Newtonian physics.
2) They would repel one another as a function of distance squared.
3) Falling into a black hole is not destruction but compaction. At high enough energies non-fundamental particles can be broken down into their constituent particles by breaking the nuclear bonds that hold them together.
4) This is called a degenerate gas. It exists at the core of White Dwarf stars.
5) The time delay is the absorption and emission not the indirect path. The clarity depends on the composition of the material and whether the light is reflected/refracted (and at what angle) internally.
6) The nature of matter at the center is unknown, but the black holes still bends space so we assume the matter is still there and take the center of mass to do calculations.
7) Yes. From some frames of reference the Sun hasn't gone out and from others it has. Either one could be considered correct. This is called the relativity of simultaneity and it is indeed relative if the events are not causal.
8) Gravity bends space and light travels through space.
9) He would only have a few seconds to do anything in his spaceship.
10) If they apply the scientific method yes. If they count how many shrimp are in a bucket of water for fun then no.
11) The one that was farther away would be moving faster with respect to the surface, but colliding with something is equivalent to "seeing" outside. | [
"One of the most cited works in this area, Chi et al. (1981), examines how experts (PhD students in physics) and novices (undergraduate students that completed one semester of mechanics) categorize and represent physics problems. They found that novices sort problems into categories based upon surface features (e.g... |
the plot of atlas shrugged | Wow. I'm looking at thirteen complete non-answers right now. I'll try to add something constructive, but no promises.
The basic plot of the book is actually in the title. Atlas (yeah, like the book full of maps) is a figure from Greek mythology. He's what's called a Titan, a race of very old, very powerful god-like figures. They gave birth to another generation of god-figures called the Olympians. The Olympians fought a war against the Titans, and won. Atlas, for his part in the war, was sentenced to stand at the edge of the world and hold the sky on his shoulders. That was his punishment for being on the losing side.
Except in art, over the past few thousand years, Atlas has often been depicted as holding the *Earth* on his shoulders. This isn't really what the original myths said, but it's become so widely recognized that it's how Atlas is generally thought of today.
Well, the title of the book is "Atlas Shrugged." Which, if you imagine a god holding the world on his shoulders, should be a pretty evocative image.
As far as the details go, the book is set in a world that's running down. Industries are being nationalized, people are apathetic and unambitious. But a couple people aren't happy about that. There's Dagny Taggart, who runs a railroad, and Hank Reardon, who runs a steel foundry. They both feel really strongly that people should work hard and do important things. Dagny wants to expand her railroad to move freight around the country, and Hank has just invented a new metal alloy that's going to make really good rails for trains to run on. But each of them encounters resistance along the way from people who resent their ambition and their drive, and they have a hard time of it.
Eventually, prominent industrialists and business leaders start to disappear. Like literally disappear: it's like they've been kidnapped or something. Their companies are gutted, their business commitments abandoned … it reaches the point of being a real national crisis. Imagine if the heads of companies like Wal Mart and UPS and Home Depot and a bunch more just shut down their companies all on the same day, and left millions of people out of work. It'd be a catastrophe a lot like the one depicted in the book.
Dagny and Hank end up stumbling across an abandon invention. I forget the details, but it's something really important, like a perpetual-motion machine or something. Just left laying in the corner of some abandoned factory. They start to wonder what the hell's been going on, and whether this has anything to do with the disappearing business and industry leaders. So they go on a hunt. This part of the book is basically a mystery story, as Dagny and Hank try to track down the person who invented the perpetual-motion machine, and see if they can get to the bottom of the disappearances.
Dagny follows the trail of clues, but ends up crashing her small plane in a valley way up high in the mountains. There, to her surprise, she finds all the "kidnapped" business leaders, and more. Scientists, artists, engineers, all kinds of brilliant, ambitious people. They've all created this new town there, organized by a guy named John Galt. Galt explains to Dagny that he got fed up with the way the world is going, so he decided to try to do something about it. He went, quietly, to all these smart people and persuaded them to quit. Just quit. Just walk out on their jobs, their companies, their families, everything, and come start this new town with him.
See, Galt figured that most of the good things that go in the world are the result of the hard work of a pretty small number of people. It's what they sometimes call the "80/20 rule." Eighty percent of the work gets done by twenty percent of the people, that kind of thing. Well, Galt didn't think that was a very good idea, so he decided to change it. His plan was to get all of those "twenty percent" people to join him in withdrawing from society. Once all those people quit, the world would just grind to a halt, because everybody who was making important things happen would've stopped. After everything collapsed, Galt and his friends would come out and start building from scratch, with the intention of creating a more just world where everybody contributes and nobody slacks off.
So that's what he did. He convinced all these smart people to "go on strike." Only it gets ugly. The government, panicked at the economic disaster, starts trying to nationalize industries. They seize companies, force inventors to give over their ideas, basically try all these completely wrongheaded ideas, never understanding the real cause of the problem. Eventually they track Galt down and arrest him. They torture him to try to get him to call off the strike, but he doesn't give in, until his friends manage to rescue him and take him back to the valley.
And then everything just goes downhill. The big turning point in the book is the moment, right at the end of the story, where the electricity supply finally quits, because there was nobody to keep the generators running. And all at once, the lights of New York City go out.
Sometime later, having weathered the collapse in their valley, Galt and his friends decide it's time to go back out into the world and start rebuilding.
People love to complain about the book and make fun of it for political reasons. I always wonder whether the people who do have ever actually read it. Cause while it's got flaws, overall it's a really cool story. | [
"Atlas Shrugged is a 1957 novel by Ayn Rand. Rand's fourth and final novel, it was also her longest, and the one she considered to be her \"magnum opus\" in the realm of fiction writing. \"Atlas Shrugged\" includes elements of science fiction, mystery, and romance, and it contains Rand's most extensive statement of... |
Is there really no way to know whether or not a shelter dog has rabies until/unless symptoms arise? | Yup. Only way to test for rabies is observation in quarantine or brain tissue. And the latter is the only real, definitive way.
> The shelter giving my dog the regular rabies vaccine for dogs wouldn't do anything if he was already infected with rabies, right?
Depends on progression of the disease.
Ideally, the shelter should do quarantine before putting animals up for adoption, but it's a 90 day quarantine for an unowned, unvaccinated animal, so it's not really feasible. It's kind of...'assumed' that the dog doesn't have rabies though, since it's relatively rare in the grand scheme of things.
| [
"Local animal control agencies or police are sometimes able to capture the animal and determine whether or not it is infected with rabies. This is important if the dog appears sick or is acting strangely.\n",
"It can be prevented in dogs by vaccination, and cleaning and disinfecting bite wounds (post-exposure pro... |
Were there other attempts at peace during World War 1? | There were two notable attempts by the papacy to broker a peace deal. In January of 1915, Benedict XV sent a papal diplomat as an envoy to Austrian emperor Franz Joseph. That diplomat was Eugenio Pacelli (who in 1939 would be elected pope and would take the name Pius XII). The goal was to try to keep Italy out of the war by having Austria agree to Italian territorial demands. This initiative was a failure.
In 1917, Pacelli was again selected to try to get Kaiser Wilhelm of Germany to agree to Benedict XV's 7-point peace plan. As Robert Ventresca says,
> [i]n the end, the discussions of the summer of 1917 went nowhere. Benedict XV's peace plan was effectively dead in the water. Despite some promising starts made by Pacelli in his first meeting with the German chancellor, the German military high command was in no mood for the concessions Bethmann-Hollweg had seemed ready to accept earlier that summer. (*Soldier of Christ*: The Life of Pope Pius XII*, pg 48)
So, early papal efforts to call for peace and keep the war from expanding were unsuccessful, as was the 1917 7-point proposal by Benedict XV. | [
"The obligation to refrain from separate peace was also made during the Second World War in both camps. The Tripartite Pact between the German, Italian and Japanese governments committed the three to prosecute the war together. On the Allied camp, that obligation was contained in the United Nations Declaration of J... |
What causes the pale greenish tint we get when we are nauseous? | I googled that and got the answer pretty fast. it apparently has to do with the blood leaving your face leaving you with the yellow of your skin and the blue of your capillaries.
| [
"It may also result from inflammation or congestion of the vaginal mucosa. In cases where it is yellowish or gives off an odor, a doctor should be consulted since it could be a sign of several disease processes, including an organic bacterial infection (aerobic vaginitis) or STD.\n",
"It is caused by a defect in ... |
how did letters like g and j, or c and k, come about? why do they share a common sound? | I think it's best expressed by a quote from James Nicoll:
*The problem with defending the purity of the English language is that English is about as pure as a cribhouse whore. We don't just borrow words; on occasion, English has pursued other languages down alleyways to beat them unconscious and riffle their pockets for new vocabulary.*
Bottom line, some of the languages we've beaten unconscious used C, and others used K. Some used G, and some used J. When they all were brought together in the English language, there was a bit of redundancy. | [
"For historical reasons, the consonant is written \"k\" in Czech words like \"kde\" ('where', Proto-Slavic *kъdě) or \"kdo\" ('who', Proto-Slavic *kъto). This is because the letter \"g\" was historically used for the consonant . The original Slavic phoneme changed into in the Old-Czech period. Thus, is not a sepa... |
how do sports commentators know all the players and their backgrounds so readily? i realize they are fed the info beforehand but they seem to spit out the info at appropriate times and so easily. | They typically have notes on hand during the broadcast, additionally they have a producer in the truck feeding them information. | [
"As a sports analyst you can go on different career paths within the field and even hold more than one position at once. First we have a sports journalist who reports to the public in the form of writing and includes information about sporting topics, events, and competitions. A sports commentator and sportscaster ... |
During the Cold War, why was it necessary for the USA and the USSR to build arsenals of literally thousands of nuclear weapons, enough to destroy all human life multiple times over? | This is more of a question about nuclear war strategy than history but here goes:
The buildup has to do with theories on nuclear war that require establishing enough of a strategic nuclear force to ensure a second strike capability. Theoretically, one side would attempt a counter-force first strike to nullify enemy strategic nuclear assets, which would leave the enemy country at the mercy of the aggressor. As a result, each side would have to build up enough of a strategic deterrent, through land based silos, SLBMs, and strategic bombers, to ensure that it would be able to reciprocate to any first strike with massive nuclear retaliation, hence the second strike. Since building up additional nuclear assets would require additional weapons to destroy them, both sides were caught in an arms race that resulted in many thousands of nuclear weapons. Arsenals basically kept growing until the introduction of the SALT I (1972) and SALT II (Effectively 1979) treaties and eventually the START (1991) treaties. You should keep in mind that the vast majority of nuclear warheads are tactical warheads which would be deployed on the tactical or operational level rather than the strategic warheads equipped on the ICBMs. | [
"At one time, the Soviet Union maintained the world's largest nuclear arsenal in history. According to estimates by the Natural Resources Defense Council, the peak of approximately 45,000 warheads was reached in 1986. Roughly 20,000 of these were believed to be tactical nuclear weapons, reflecting the Red Army doct... |
What is the "speed limit" beyond the event horizon of a black hole? | > if light crosses the event horizon of a black hole, does it speed up beyond the speed of light on its way to the center?
Not really. What happens is that past the event horizon, the escape velocity (think: how fast would something, say, a rocket, need to go to "lift off") becomes faster than the speed of light. The photon itself won't speed up. It just can't escape the gravity. | [
"A black hole in general is surrounded by a surface, called the event horizon and situated at the Schwarzschild radius for a nonrotating black hole, where the escape velocity is equal to the velocity of light. Within this surface, no observer/particle can maintain itself at a constant radius. It is forced to fall i... |
What was the Value of a Knight and other warriors? | This is a very complicated question to answer, and there isn't really a definitive price-list for armor and weapons. I'm not sure that there is an answer at all for the Viking, as we don't really have financial records from Vikings.
For the knight, the availability of materials and quality of materials and craftsmanship would factor into the price quite heavily. There was new armor intended to be sold to average soldiers and old armor that was still being worn second-hand, and these could be quite cheap. On the other hand, the fine parade armor worn for display by the kings and great magnates of Europe was incredibly expensive. The type and amount of armor that you've described here would have been at the high end of armor intended for use in battle, which means that it would be quite expensive.
That said, it's nearly impossible to provide an itemized accounting of how much these items would have cost. This is because usually if we have records for how much somebody spent on armor, it's all jumbled into one amount. So it's not very easy to tease out what the individual pieces cost. Take for example Joinville's accounting of how much his armor cost. He remarks in the *Life of Louis* that he would need 800 pounds to mount and arm himself and feed himself and two knights. A livre is a monetary unit like a dollar or a pound. However, this doesn't really help us figure out how much the armor itself or any particular piece actually cost! It's not easy to find the range of the cost of armor, either, but I can try to give you some touch-stones.
First, a word on currency. Medievalists work in solidi, pounds, and livres for the most part. These are all kind of sort of equivalent such that a livre in France in 1350 was probably roughly worth a pound in England in 1350. It's a lot harder to account for inflation/deflation across time.
It's easiest to tease out numbers on the horse. In the fourteenth century, a good horse fit for battle would cost around 25 pounds. On the other hand, in the mid 13th century Joinville remarks that Louis wouldn't give him the horse of a disgraced knight because it was still worth "eighty to a hundred pounds, which was no small sum." In 1337 Edward III paid 168 pounds for a warhorse, and that seems to be at the very high end.
The average knight would have purchased a hauberk or mail shirt, a sword, and a horse in preparation for battle, along with other necessary items. Andrew Ayton estimates that the average cost for a simple knight to outfit himself during the hundred year's war was approximately 40 to 50 pounds. The list of armor you've given far exceeds this. It would probably cost, including the horse and horse's armor, between 100 and 150 pounds, at the low end.
Now, the final part of your question is the hardest! It's nearly impossible to calculate an exchange rate between medieval currency and modern currency. Too many economic and social factors have changed. Instead, we tend to make comparisons to things like income from land (via rents). So, the 40 pounds that it would take the average knight to equip himself is actually roughly equal to the amount of income the average knight would receive from land rent in a year! You could think of this like the average middle class person in the US going to buy a new, mid-range mercedes. It's going to cost them their entire salary for the year so they'll either have to save up for it or take out a loan. Comparatively, a peasant family would earn somewhere around 2 pounds per year, and could never afford a war horse or armor.
Of course, some knights were wealthier and therefore could afford more expensive sets of armor. There was a trial by combat in 1386 between a knight and a squire, and we know that the knight had a set of armor similar to what you've described. Although we don't know how much the knight's armor cost, we do know that his estates produced roughly 400 to 500 livres in a year. That's ten times what the average knight would earn and more that 200 times what the average peasant family would!
sources:
[Memoirs of the Crusades](_URL_0_) by Jean de Joinville and Geoffroi de Villehardouin
[Medieval Warfare: A History](_URL_3_) by Maurice Keen. I especially quoted from Andrew Ayton's article *Arms, Armour, and Horses*.
[Medieval Weapons: An Illustrated History of their Impact](_URL_2_) by Kelly DeVries and Robert D Smith.
[The Last Duel: A True Story of Crime, Scandal, and Trial by Combat in Medieval France](_URL_1_) by Eric Jager. | [
"Knight was described as \"a gentleman, whose eminent worth is still remembered by many now living; whose high character for upright conduct and integrity, rendered his life as honorable as it was good, and caused his death to be lamented by every one as a public loss\".\n",
"Knight has appeared or been featured ... |
why do even numbers feel safer and more pleasing than odd numbers? | Because it is more familiar to you. You have 10 fingers, 10 toes, two eyes, two ears, two arms, two legs, etc. Yes, you have one nose and one mouth but the number two satisfies your natural sense of symmetry more easily. The reason that five is comfortable is because of five fingers and five toes. | [
"For an example of odd numbers being friendly, consider 135 and 819 (\"abundancy\" 16/9). There are also cases of even being \"friendly\" to odd, such as 42 and 544635 (\"abundancy\" 16/7). The odd \"friend\" may be less than the even one, as in 84729645 and 155315394 (\"abundancy\" 896/351).\n",
"This strong dep... |
how do latrines flush away stool but get blocked because of tissie/toilet paper? | Toilets have pipes. A lot of paper will be difficult to compress and fit through those pipes. Turds, meanwhile, are relatively small and squishy. | [
"If clogging occurs, it is usually the result of an attempt to flush unsuitable items, or too much toilet paper. Clogging can occur spontaneously due to limescale fouling of the drain pipe, or by overloading the stool capacity of the toilet. Stool capacity varies among toilet designs and is based on the size of the... |
What did knights/lancers do with their lance after a successful charge? | Typically a lance is used once in a battle, you charge, the lance either becomes embedded in your target, breaks or misses, in either case you drop it and draw a sidearm for close quarters fighting. There have of course been cases where lancers or knights have wheeled around, gone back to their original starting point, rearmed and charged again but I would consider this an exception to the rule. Typically a charge was intended to be the deciding move in a battle, shattering all or a crucial part of the enemy formation and thus ending the battle. | [
"In Europe, a jousting lance was a variation of the knight's lance which was modified from its original war design. In jousting, the lance tips would usually be blunt, often spread out like a cup or furniture foot, to provide a wider impact surface designed to unseat the opposing rider without spearing him through.... |
how elevators know what floor to go to and how they stop perfectly *nearly* every single time | A certain number of rotations of the gears causes a specific change in height of the elevator. This isn't something that has any drift to it, it's pretty constant on the kind of scale we care about.
A little tuning and you have it set with all the heights. Not much to it. | [
"Elevators have a car top inspection station that allows the car to be operated by a mechanic in order to move it through the hoistway. Generally, there are three buttons: UP, RUN, and DOWN. Both the RUN and a direction button must be held to move the car in that direction, and the elevator will stop moving as soon... |
Upon launch, what kept the Space Shuttle from tilting backwards towards the orbiter? | If the rocket nozzles generate a thrust that points through the center of mass of the shuttle, then it won't rotate. | [
"The vehicle began re-entry by firing the Orbital maneuvering system engines, while flying upside down, backside first, in the opposite direction to orbital motion for approximately three minutes, which reduced the Shuttle's velocity by about . The resultant slowing of the Shuttle lowered its orbital perigee down i... |
special economic zones | It basically means the country or state has declared certain areas to have separate trade/regulation/economic policy than the rest of the country or state. It is typically done to encourage trade and boost their economy.
Here is an example. Two islandic countries fish for widgets. Country A has a socialist economy and very high taxes and regulation on businesses. Country B is capitalist and has a free market mentality. The cost to get the widget out of country A is much higher and they cannot compete on the global market. So the country declares a special economic zone for the industry/port. The widget company now has a separate set of laws and taxation than the rest of their country. | [
"A special economic zone (SEZ) is an area in which the business and trade laws are different from the rest of the country. SEZs are located within a country's national borders, and their aims include increased trade balance, employment, increased investment, job creation and effective administration. To encourage b... |
After the Stanford Prison Experiment, what happened to all the ‘prisoners’ and ‘guards’ who were involved? Did any of them sue/have long term mental health issues from what went on in there? | I think it's well worth pointing out here that the Stanford experiment is highly controversial among psychologists, and the high reputation it has among the general public is by no means reflected in its reception by professionals.
There are numerous critiques of the experiment from the point of view of its design and, perhaps more seriously, several recent "exposés", and a film, [based on interviews with participants, ](_URL_5_)which contain significant charges regarding the degree to which the results were deliberately engineered by the "prisoners" and "guards", out of boredom or mischief.
In addition, the psychologist responsible for the experiment, Zimbardo, has been attacked for [giving out incorrect information about the trial design and the conditions under which the student participants took part](_URL_2_).
Fnally, [an attempt by a team of British psychologists](_URL_4_) to replicate the experiment under the same conditions that Zimbardo asserts he applied [failed miserably](_URL_1_).
As a result of all this, the Stanford experiment is actually not very widely taught in psychology classes and d[oes not appear in quite a number of standard textbooks](_URL_0_).
All of these charges would tend to suggest not only that the famous experiment was, at best, severely comprised, but also that it was much less likely than you might expect to inflict long term damage on the participants. For balance, you might like to know that Stanford maintains a resource that links to both [major critiques of the study](_URL_6_), and Zimbardo's [defences of it](_URL_3_). | [
"In the summer of 1971 a Stanford psychology professor, Philip Zimbardo, conducted a study of the psychological effects of becoming a prisoner or prison guard which is known as the Stanford prison experiment. The experiment, which was funded by the Office of Naval Research, surprised the professor by the authoritar... |
Were there "baby boomer" generations as a result of large armies returning from battle in ancient times? | Its important to remember that the Baby Boom in 1950s America was not simply caused by troops returning from WW2. Remember there was no real Baby Boom in Britain or France in response to WW2 and even within America after WW1 there was no real "boom" in population. David Faber in *The Age of Great Dreams* argues that the boom was more caused by availability of housing in the suburbs and widespread consumer goods in the economy which a huge amount of young couples feel confident enough to start families at the same time especially when you consider many of them came through the Great Depression. They saw the new opportunities as a great chance also considering the uncertainty in America due to the Cold War starting.
I know I did exactly answer your question and I don't have much data on battles in ancient times, but I would answer no since even America's baby boom was not the result of a large army returning, that is just an oversimplification of history. | [
"BULLET::::- Baby boomers, also known as Generation W or the Me Generation, are the generation that were born mostly following World War II, typically born from 1946 to 1964. Increased birth rates were observed during the post–World War II baby boom making them a relatively large demographic cohort.\n",
"One prop... |
Were there black KKK members? | Maybe. Take a look at this 1920s [application](_URL_0_)(warning, PDF) to join the order. Note question 9: "are you of the white race or of a colored race?" Keep in mind that these forms are for vetting members. However, the question is tantalizing when we realize that the 1920s Klan, which has received the most scholarly attention, had several auxiliaries. The only auxiliary that has received any sustained attention is the Women's Ku Klux Klan (WKKK), beginning with Blee's work. But there are references to other Klan auxiliaries. There was the Junior Ku Klux Klan, Tri-K Girls, the American Krusaders, and the Ku Klux Kiddies. However, there are also references to another Klan auxiliary, the Klan's Colored Man auxiliary. It is unclear how successful the Klan was at organizing this auxiliary. One should not take the lack of archival deposits as evidence of their inability to organize the auxiliary; the Klan was very secretive and destroyed many of their documents. There are scattered references about membership, especially secondary resources, but it is uncertain how reliable these sources are. One such compendium of references is [this](_URL_1_) Klan website (WARNING: NSFW, KLAN WEBSITE). So, I'm afraid we cannot answer your questions right now. It is a big maybe. | [
"The White Knights of the Ku Klux Klan (WKKKK) operated in the Southern District of Mississippi and elsewhere, and was a secret organization of adult white males who, among other things, targeted for violence African Americans they believed were involved in civil rights activity in order to intimidate and retaliate... |
how do sodas travel the country all carbonated but as soon as you get one alone and it shakes up, its flat?! | I would like to add that soda in its final form rarely if ever makes a cross-country trip. What happens with the big companies is they stir up the beverage base at their own place (this is JUST the flavorings and stuff), then ship *that* to the various regional bottling factories who then mix it with carbonated water, and then ship the final product out.
This is why when you see Coke and Pepsi delivery trucks, they're *always* driving a "day cab" semi, which doesn't have the sleeper area in the back. Don't need the sleeper area if you clock in make your rounds and clock out and go home each day. | [
"Home soda siphons can carbonate flat water through the use of a small disposable steel bulb containing carbon dioxide. The bulb is pressed into the valve assembly at the top of the siphon, the gas injected, then the bulb withdrawn. Soda water made in this way tends not to be as carbonated as commercial soda water ... |
How exactly is a photograph actually stored as 1's and 0's on a computer? | Let's talk about [bitmaps](_URL_0_).
The simplest case is a black and white bitmap (which will literally be a bit-map... the 0s will be black and the 1s will be white. And it will be 32 by 16 pixels.)
You have to tell the computer at least one thing about the bitmap:
1. How many pixels wide is it
So you need to put that in a file. So there's a number at the front of the file. So the computer needs to be able to make an assumption about how big that number might be, so it knows when to stop reading "how wide is this bitmap" and starts reading the zeros and ones that make the picture. Maybe you and the computer agree "the first four bytes of the file are the width", so your file goes like this:
00000000 00000000 00000000 00100000
And the computer says "0h, that means 32 to me, so everything after this is the picture". Then you want to make a white dot (because black is "zero" or "none), so you set the next numbers to
00000000 00000000 00000000 00000000
00000000 00001111 11110000 00000000
00000000 11111111 11111111 00000000
00000011 11111111 11111111 11000000
00001111 11111111 11111111 11110000
00111111 11111111 11111111 11111100
01111111 11111111 11111111 11111110
01111111 11111111 11111111 11111110
01111111 11111111 11111111 11111110
01111111 11111111 11111111 11111110
00111111 11111111 11111111 11111100
00001111 11111111 11111111 11110000
00000011 11111111 11111111 11000000
00000000 11111111 11111111 00000000
00000000 00001111 11110000 00000000
00000000 00000000 00000000 00000000
And there you have your bitmap. For this example I ordered the numbers in columns so you could see them on the screen, but to the computer they'd just be bits.
Now if you want to do a color bitmap, it gets more complicated. Because there are many [ways to mix colors](_URL_2_). There's Red/Green/Blue, then there's Hue/Saturation/Brightness, and several others. So you'll need a number for each of those, to say (for "RGB": "how much red, and how much green, and how much blue") So instead of using one bit, you need to save several, for each color. Commonly bitmaps use 8 bits (or 1 byte) to measure each color. So if you made the same image using RGB, black would be
[ R ] [ G ] [ B ]
00000000 00000000 00000000
and white (or "all the colors") would be
[ R ] [ G ] [ B ]
11111111 11111111 11111111
So the file becomes ~~3~~ **24** times larger. But now it can be in color. I'm not going to type out a 32-by-16 pixel RGB bitmap, because, well, that would be silly.
Commonly, bitmaps can be compressed (GIF files are compressed) so that instead of writing all those 1's, you have a part at the top of the file (before the actual bits) where you say--for instance--"any time you see 00000001 00011000, I really mean that the next 24 bytes are all 1's", which saves you 22 bytes worth of space. So the simple way to make smaller images is to keep a list of "shortcuts" that you can expand out later.
Now for JPEG, things get more complicated, because there it's more like a tiny program, ~~that goes over the picture and not only finds runs of things that are the same, but patterns that repeat, and it says "this part of the picture is a lot like this other part of the picture, so we'll just save it once and refer to it later" but it can also say "this tiny part looks a lot like this bigger part. So throw away the bigger part to save space" or other ways of looking at individual areas of a photo and deciding if they're alike enough to save as shortcuts. Then the computer takes all of those instructions (which are part of "The JPEG standard") and interprets them to reproduce something that's more or less like the original.~~ What [tugs_cub says below](_URL_1_) (Though I thought that for the results of the tiling, it would only keep one copy of each distinct tile?)
| [
"2. Assume the photo we take is made of 4 blocks that are adjacent to each other and we set the luminance scale for each of the 4 blocks of original photo to be 10, 100, 205, 245. Thus, the image looks like the first figure on the right. \n",
"The camera phone records pictures in JPEG format, but the Krave can al... |
irc | My favorite description of IRC has always been "Multiplayer Notepad" | [
"IRC was created by Jarkko Oikarinen in August 1988 to replace a program called MUT (MultiUser Talk) on a BBS called OuluBox at the University of Oulu in Finland, where he was working at the Department of Information Processing Science. Jarkko intended to extend the BBS software he administered, to allow news in th... |
AMA: Vikings | How far east did the Vikings go? I'm aware of the Volga Vikings and their visits to Baghdad but did they go further east? How accurate is Ibn Fadlan's description of the Ship Burial he described?
| [
"\"The Vikings\" is a British-based society of re-enactors, dedicated to the study and re-enactment of the culture of the Viking Age (790–1066) and the display of authentic Dark Ages living history and combat.\n",
"The Vikings - Vinland is an organization of Viking reenactors, consisting of 12 local member-groups... |
'weight cutting' in combat sports | Many combat sports are divided into weight classes. Being at the top of your weight class can give a slight advantage, so if you can lose a few pounds and drop into the next lower class you'll be at the top of that rather than the bottom of your original one. | [
"Fighters can cut weight for a \"day before\" fight weigh-in with modern conditioning and training methods and regain the same weight on \"day of\" the fight. The purpose of a catchweight is to compensate for the ability of bigger boxers to cut weight before a \"day before\" fight weigh-in and regain the weight to ... |
what is the point of the catcher in the rye? | There really isn't a point, if you want to know the truth. It's just this old crumby book that a whole bunch of phonies _say_ they like even though they don't really understand it for one second. You can always tell when someone's that kind of phoney 'cause they try to impress you with big talk about themes and points and morals and you know the second they start up with that crap that they can't even tell you anything about anything _real_, like a baseball glove or a talk with your sister, or where the ducks go when the lake freezes over. They go on and on about all that lousy crap instead of the _in_teresting parts, where it's nice and exciting and all, it's nice when somebody tells you about their life. But these sad old bastards, they don't have a clue about what the goddam book's about. It's pretty dumb, really, if you think about it. | [
"The name of Rye is believed to come from \"rie\", meaning a bank. Medieval maps show that Rye was originally located on a huge embayment of the English Channel called the Rye Camber, which provided a safe anchorage and harbour. Probably as early as Roman times, Rye was important as a place of shipment and storage ... |
how it is that we exert the same gravity on earth as earth exerts on us? | Your phrasing is a bit off. To be a bit precise, gravity attracts us and the Earth *to each other*.
The force of gravity between two objects is measured by three things: the mass (weight, for ease of reference) of the first object, the mass (weight) of the second, and the distance between their centres. That force **acts equally** on both objects, attracting them to each other and pulling them together. But if one object is much lighter than the other, the same force will move it more.
Imagine you somehow turn gravity off for a second, move three feet (1 meter) up from the Earth's surface, and then gravity back on. You two attract each other until you touch.
But the Earth is MASSIVE, so massive that the little bit of attractive force that pulls it to you is not really gonna move it at all. Instead, the force that pulls you to it brings you downward toward it because you're much lighter. You're much much easier to move, so the force more-or-less is only moving you.
If you were blown up instead so you were the exact same mass and size as the Earth, you two would move together instead. | [
"The gravity of Earth, denoted by , is the net acceleration that is imparted to objects due to the combined effect of gravitation (from distribution of mass within Earth) and the centrifugal force (from the Earth's rotation).\n",
"The gravity of Earth is the acceleration that is imparted to objects due to the dis... |
Were people in Victorian times actually as weak health-wise as they are portrayed in novels from the time period? | I cannot speak to the actual, physical health of Victorians, but I did once write an answer on the related subject of why one shouldn't take representations of fainting in period fiction as just a reflection of what people were actually doing:
[How did fainting in the Victorian era become so gendered? What social conventions led to the loss of consciousness to be so strongly identified with women?](_URL_0_) | [
"The status of the poor is one area in which huge changes occurred. A good illustration of the differences between life in the Georgian and Victorian eras are the writings of two of England's greatest authors, Jane Austen and Charles Dickens. Both writers held a fascination for people, society and the details of ev... |
Before Einstein, did nobody else consider there was a deep relationship between gravity and space time? | Depending on how you see it, there is also no deep relationship between gravity and spacetime in General Relativity. GR is originally just a generalization of Special Relativity, such that two reference frames relate to one another by Lorentz transformation when acceleration (which means force) is involved. This means, if you switch from one point of view to another, the translation of the physical system into your new point of view is given by the Lorentz transformations.
If you use Minkowski's geometric formulation of Special Relativity, acceleration is the same as a curvature of spacetime. Regardless of what is causing the acceleration, it is necessary to formulate it as curvature in a relativistic framework.
The common interpretation is that mass "causes" a curvature of spacetime. But GR also works as a theory of each other interaction, if you interpreted the associated charge as causing a curvature in spacetime. To associate charge with curvature is actually also the basis for the Kaluza-Klein approach and Yang Mills theory that underlies the standard model.
The difference between GR and a Newtonian theory of gravity is just the Lorentz-invariance, which means: no speed bigger than the speed of light in all reference frames. If you calculate the Lorentz invariance out of GR, you still get the Newtonian gravity potential.
Thus, the big progress of Relativity is that all physical systems have to obey Lorentz transformations. The stuff with mass producing a curvature in spacetime is just an interpretation based on the mathematical formulation, so to speak taking the mathematics literally. | [
"In 1905, Einstein introduced special relativity (even though without using the techniques of the spacetime formalism) in its modern understanding as a theory of space and time. While his results are mathematically equivalent to those of Lorentz and Poincaré, it was Einstein who showed that the Lorentz transformati... |
What causes the scars on the ocean floor? | The long linear irregularities in your image look image look like what we call "artifacts", a direct result of the mapping techniques. Most of what we have for the vast ocean floor bathymetry is fairly low resolution, thus there is a lot of smoothing. When a ship makes a single pass through a poorly mapped area and gathers higher resolution data it creates what looks like a more rough strip.
There are plenty of natural processes which create seafloor lineations.
[The mid-ocean ridge system](_URL_0_) is composed of off-set linear segments. At [Oceanic Core Complexes](_URL_1_) you get striations in the seafloor.
[Ice](_URL_2_) can scour the seabed in sometimes straight lines.
I really think what you are seeing is an artifact of merging data sets though.
| [
"A large number of injuries, up to 66%, are caused by collision with a surfboard (nose or fins). Fins can cause deep lacerations and cuts, as well as bruising. While these injuries can be minor, they can open the skin to infection from the sea; groups like Surfers Against Sewage campaign for cleaner waters to reduc... |
what is the difference between baking powder and baking soda? | The top comment is correct, but in case it's too technical:
Both baking powder and baking soda are used to create a rise in baked goods. The chemical reaction they cause makes bubbles that puff up the dough. Baking soda needs an acid added to the dough to make that reaction happen (like your grade school volcano). Baking powder is baking soda plus an acid that activates when it gets wet. Which one you use depends on the recipe (is there an acid?) and how much rise you want (baking soda is stronger but too much of either powder can affect tastes so sometimes you want a big rise and you use both). | [
"Many forms of baking powder contain sodium bicarbonate combined with calcium acid phosphate, sodium aluminium phosphate, or cream of tartar. Baking soda is alkaline; the acid used in baking powder avoids a metallic taste when the chemical change during baking creates sodium carbonate.\n",
"In cooking, baking sod... |
How do polarizing filters “know” the orientation of incoming photons? | It's hard to do better than this 60 Symbols video:
_URL_0_
It's not about "knowing" it's that if the incoming light is not perfectly polarized already then no matter what angle you choose it will have SOME component along that axis and that is the component that survives the filter, which is made of long conductive molecules that only efficiently transmit the portion of an oscillating electric field (i.e. light) that is oscillating in the direction ~~of~~ **perpendicular to** their length. | [
"As shown in the figure, the analyzing filters are constructed of a quarter-wave plate (QWP) and a linearly polarized filter (LPF). The QWP always transforms circularly polarized light into linearly polarized light. However, the angle of polarization of the linearly polarized light produced by a QWP depends on the ... |
why are the refugees blocking the eurotunnel in callais not arrested/kicked out/processed/in france? surely they are illegally staying there too? is the french govn't just lazy or is there some technical reason? | They aren't exactly tolerated - the local police break up the camps and arrest people whenever the numbers start to rise significantly, as over this last summer. The current Mayor of Calais seems determined to see something done now that numbers are rising again, and has threatened to blockade the port if the UK doesn't help with the problem.
The problem, as ever with refugees, is what to do with them if you do arrest them. Some will refuse to state which country they originated from, some will have fled a country where they are genuinely at risk. You can't lock them up without building a lot more expensive prisons, and sending them back may be a waste of money too if they will be free to return straight away. Neither of the leading political parties pretend to have an answer to this problem, while the Front National is sure that it would deport illegal immigrants (regardless of their personal safety) but as far as I can see, isn't clear on where to, how many times, or how much it would cost.
The FN says it would only deport *illegal* migrants anyway. Some of the refugees are illegally in France - they refuse to apply for asylum in France because then they'd lose the right to apply for asylum if they reached the UK - but many more are legally there, waiting for their asylum claims to be processed. They live rough around Calais simply because they have no money. There used to be a refugee camp at Sangatte for such people, but Sarkozy closed it, so he's responsible for the homeless refugee problem too. I have read that French law states that asylum seekers are entitled to accommodation, but the existing accommodation is full. So there is no room for more, even though - according to the UN refugee agency - a quarter of the refugees in Calais are children.
The local police and local authorities tolerate them because France is a country with highly centralised authority. The locals do not want these 'migrants,' and I reckon that if left to their own devices, the local authorities would quickly deal with the situation. But the PS (Parti Socialiste) are in charge in Paris, and they are to say the least, quite soft on illegals. With maybe the exception of the PM, Manuel Valls, who is largely not trusted or liked by other more leftist members if the PS. A vote of confidence in fact was held here yesterday, and Valls barely got through, with several of the left wing of his own party either abstaining or voting no. And the Verts (Greens) who are part of his coalition almost uniformly opposed him because he is seen as a right wing wolf in sheep's clothing.
THIS is why the FN are polling so well, by the way. Everyone knows that having thousands (approximately 100,000 or so illegals have crossed into Italy this year alone, with reports of another half million waiting in North Africa) are a huge social and economic problem, and yet the leading parties do not even pretend to have any answers.
Nature abhors a vacuum. | [
"The Calais migrant crisis led to escalating tension between the UK and France in the summer of 2015. The UK blamed France for not doing enough to stop migrants from entering the tunnel or making attempts to scale fences built along the border. The British Prime Minister David Cameron released a statement saying th... |
Is there a reason that baldness in babies follows the same general pattern as Male Pattern Baldness? | I think you may have a flawed premise here. Babies generally don't follow male pattern baldness. If they have very thin hair, it is generally very uniform.
Maybe someone else can give you a better answer, but I haven't been able to find a single example of a male pattern baldness newborn for about an hour now. | [
"Although men grow hair faster than women, baldness is much more common in males than in females. The main cause for this is \"male pattern baldness\" or androgenic alopecia. Male pattern baldness is a condition where hair starts to get lost in a typical pattern of receding hairline and hair thinning on the crown, ... |
I read about children working underground in coal mines during the Industrial Revolution. Is that accurate? | Until 1842, children did work underground in substantial numbers.
[An accident at Huskar Colliery in Silkstone](_URL_1_), near Barnsley in 1838 clearly shows this. A stream overflowed into the ventilation drift after violent thunderstorms causing the death of 26 children; 11 girls aged from 8 to 16 and 15 boys between 9 and 12 years of age.
The Royal Commission of Inquiry into Children’s Employment of 1842 found that over 5000 children were employed for underground work, some as young as four years old.
You can read the conclusions on employment of children in mines [here](_URL_0_)
* Children (mostly boys, but also girls) did work underground from a very young age.
* The youngest often worked opening and shutting ventilation doors, a job where they spend almost the entire working day alone and in the dark.
* From the age of six, they would be employed hauling coal carriages, sometimes in very low tunnels.
* Working days were 11 to 14 hours. The better-regulated mines had some breaks, the worst not at all and many children complained of a constant, often painful fatigue.
* In case of mine accidents, young children died in explosions, were crushed under tonnes of stone or drowned. Entrusting jobs essential for mine safety to young children was actually a cause of accidents.
[This list of mining accidents 1820-1839](_URL_2_) shows many teenage and younger workers killed.
All this led to the Mines and Collieries Act 1842:
* No female was to be employed underground (as women miners wore trousers and shifts or even went topless, this work was an affront to Victorian sensibilities)
* No boy under 10 years old was to be employed underground.
* Parish apprentices between the ages of 10 and 18 could continue to work in the mines.
| [
"Boys in the Pits: Child Labour in Coal Mines is a 2000 book by Robert McIntosh, published by McGill-Queen's University Press. The book is about child labour in Canada in the 19th and early 20th centuries, with special reference to the history of boys, aged 8 to 15, who worked in coal mines. These boys worked under... |
A question on Cosmic Radiation and Electromagnetic Shielding | While the earth's magnetic field does help with cosmic rays, you are forgetting the massive attenuation that occurs due to our atmosphere. | [
"This radiation originates from outside the solar system and consists of ionized charged atomic nuclei from hydrogen, helium and uranium. Due to its energy the galactic cosmic radiation is very penetrating. Thin to moderate shielding is effective in reducing the projected equivalent dose but as shield thickness inc... |
why can a light tap or flick or what have you on my testicles hurt pretty bad, but ball-slapping sex doesn't hurt at all? | Well, during ball slapping sex, things hurt less. Hormones, adrenaline, etc. For me at least, it's common for them to be a bit sore after. | [
"Loss of blood flow is one of the biggest risks in cock and ball torture (CBT), which can be seen with loss of color and edemas. Bondage in which the testicles are tied to something else is especially dangerous, increasing the risk of the testicles getting damaged through excessive tension or pulling.\n",
"Blue b... |
why we can't see a full circle rainbow? | Because of the physical properties of rain droplet, the light entering and leaving forms an angle of about 42^(o). That means a rainbow is going to be a ring "around" the sun at 180^o - 42^o = 138^(o), or 42^o from the point exactly opposite the sun. Since that point is below the horizon, the earth itself blocks the lower portion of the rainbow.
[But not always](_URL_0_). If you are at a high enough altitude, the can be enough water droplets between you and the ground for a full 360^o rainbow to appear. | [
"From above the earth such as in an aeroplane, it is sometimes possible to see a rainbow as a full circle. This phenomenon can be confused with the glory phenomenon, but a glory is usually much smaller, covering only 5–20°.\n",
"A rainbow is not located at a specific distance from the observer, but comes from an ... |
why do sites sometimes give an error, but if you refresh it a second after it works? | Here's an example.
Let's assume the Google server that I access is in California. I type something into a Google search bar, hit search, and it goes from here in New York State to the Google California Office in 13 milliseconds (0.013 seconds).
The server in California then has to look for what I put in, which takes a couple milliseconds, and then sends that data back to me once it finds it.
This is an entire search done in less than 3% of a single second, and is the timescale we need to remember.
-----
When a site gives an error, that means the site couldn't be accessed. Or that within the couple milliseconds the server couldn't find the part that had the site you wanted.
-----
If the error is because there's too many people accessing it, then over the next couple seconds 50 to 100 people will be processed. And once they are done, there's space for your search.
This is exactly like when you are looking for a parking lot at a mall on the weekends. Every spot is filled, so you have to wait until someone leaves their spot before you can park into a spot.
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If it's because the server can't find the literal part where the site is hosted, then it sometimes takes a couple tries for it to finally find what you are looking for. I mean, look at Reddit. There's hundreds of subreddits with hundreds of pages and posts. Finding a specific post the search function means looking through all those posts on all those subs until the desired post is found. Does that sound like an easy thing to do? No it does not, because it's not an easy thing to do. Even for a program designed to search, it's going to be difficult. | [
"Once an accessibility audit has been conducted, and accessibility errors have been identified, the errors will need to be remediated in order to ensure the site is compliant with accessibility errors. The traditional way of correcting an inaccessible site is to go back into the source code, reprogram the error, an... |
Reading about the WWII pacific theather. Why the huge difference in losses? | A fast deteriorating supply situation for the Japanese and the industrial might and adaptibility of the US happend. What followed was what always follows when ideology, honor culture and courage clashes with superior firepower.
Quite simply, the IJN didn't surrender when almost any other force would have. They fought until they ran out of everything. Food, ammo, equipment, reinforcements. Usually, being cut of and running out of things it what makes a normal army surrender. The IJN fought on, sometimes even resorting to "banzai tactics" (in essence, a suicide charge) rather than surrender. | [
"The Battle of Midway, in June 1942, brought Nagumo's near-perfect record to an end. The First Air Fleet lost four carriers during the turning point of the Pacific War, and the massive losses of carrier aircraft maintenance personnel would prove detrimental to the performance of the IJN in later engagements. The lo... |
why is it called the "secret service" when it isn't secret at all? how did they get that name officially? | In 1865, the "Secret Service Division" of the US Treasury Department was formed as a federal police agency devoted to investigating and preventing money counterfeiting, which was a huge problem at the time. In it's early years it ended up doing all kinds of law-enforcement and intelligence/counter-intelligence duties. At the time, the only other federal law enforcement agencies that existed were the Post Office police and the US Marshals, both of whom have legally limited jurisdiction (US Marshals are responsible for carrying out the decisions of federal courts, such as serving arrest warrants). Later after the 1901 assassination of President McKinley, the SS would be officially tasked with protecting the President, other high officials, and foreign diplomats. Now it's two main jobs are security for the President and investigating financial crime, including but not limited to money counterfeiting. Since 2003 it's been moved from the Department of the Treasury over to the new Department of Homeland Security.
From what I've read, historians aren't exactly quite sure why it was called the Secret Service, but it might have had to do with the undercover and secretive nature of intelligence-gathering. But it was never intended to actually be a *secret* agency that the public isn't supposed to know about or anything like that. | [
"The U.S. Secret Service is charged with protecting the president and the first family. As part of their protection, presidents, first ladies, their children and other immediate family members, and other prominent persons and locations are assigned Secret Service codenames. The use of such names was originally for ... |
if horse racing tips had any merits, why wouldn't the bookies adjust their odds to match? | Betting on horse races is fairly straight forward. If more people bet on a particular horse because they think it has a good chance to win, odds will adjust. The horses with low odds stay that way because few people will bet on them. The bookies do adjust the odds, in horse racing and pretty much any sporting event. | [
"Betting exchanges compete with the traditional bookmaker. They are generally able to offer punters better odds because of their much lower overheads but also give opportunities for arbitrage, the practice of taking advantage of a price differential between two or more markets. However, traditionally, arbitrage has... |
what is that carbon fiber pattern? why is it so appealing? | Carbon fibers have extreme tensile strength to weight ratio. This is good in that a light weight component can support a larger load. However, its strength is highly directional i.e. it is strong only in one direction. So the fibers are woven into a matrix like the pattern you see commonly. The pattern also varies by the purpose it is designed for. Then a resin is added to solidify the pattern. This prevents sliding among the fibers and gains considerable strength because of that.
Think of it as a cotton fabric with glue smeared on it. When the glue dries, the fabric will be less flexible (more rigid) like thin sheet metal.
EDIT: It also looks super cool too!! [And check out the cool highlights that can be added](_URL_0_)!! | [
"Carbon fiber is of interest due to its widespread use in composite materials. Provided there are closed loops of carbon within the composite structure, eddy currents can be induced in the material. Unidirectional carbon fiber composites can have poor susceptibility when fiber to fiber contact is limited.\n",
"Th... |
- water towers | Water towers make it so that, instead of pumping water *all* the time, you just have to pump water to the top of the tower. This means you can still get water when the power goes out, and that's very important in areas where the power is likely to go out. | [
"A water tower is an elevated structure supporting a water tank constructed at a height sufficient to pressurize a water supply system for the distribution of potable water, and to provide emergency storage for fire protection. In some places, the term standpipe is used interchangeably to refer to a water tower. Wa... |
why do some foods taste just as good (or better) as leftovers the next day, when others are horrible? | It's hard to generalize it because it's different for each food. A lot of chemical processes happen constantly even after food is cooked, and it depends on it's chemical makeup, how it was cooked, how it was stored, and how it was reheated.
Firstly, reheating anything often ends up cooking it as well. Some foods care about this and some don't. A medium cooked steak can become well-done and a piece of fish can become rubber. Stew meat, on the other hand, usually only gets more tender the longer you cook it. Additionally with microwaves, because of how they work, they tend to dry and therefore toughen foods reheated in them, especially wheat products. For many breads, however, a little extra toughness is sometimes desirable.
For some foods, their quality starts to degrade as soon as they're cooked. Fries, for instance, get limp over time as the water in them dissolve it's starchy structure that gives it it's crispness, especially in the humidity of the fridge or if they are sealed in an airtight container where their own steam will do the job. The salt on them then drives that moisture to the surface making them at first slimy and then dry and stale. The oil coating the fry accelerates this process by preventing the water's reabsorption. Lastly, even when trying to reheat the fries, a microwave can never get them crispy again, and even a deep fryer will create an inferior version of the original.
Yet other foods only get better with aging, much like a fine wine. Curry and most stews get better as the flavors involved (spices, meats, aromatic vegetables, etc) have time to combine and the harsher notes give way to more subtle ones. Stewed meat also tends to get more tender as it sits and cooks as long as it doesn't dry out.
A side note about meat in general, meat that is slow cooked like stew or pot roast are cooked that way because long exposure to heat dissolves the connective tissue that holds the muscle fibers together, tenderizing the meat. The dissolved connective tissue is collagen, and is what gelatin is made of. Anyway, this dissolved protein gives soups, stocks, and stews a thickness and weight on the tongue that is unique. When made cold, it solidifies much like gelatin, and if not entirely dissolved from the meat will return it to its tough texture. However, reheating the meat with enough moisture present should redissolve the collagen and return it to its tender state.
Lastly, food tastes differently at different temperatures. Cold tends to suppress flavors both good and bad, as well as bitterness, while heat enhances more aromatic flavors. As bitterness goes down, sweet tastes are more noticeable which is why many bitter things are made more palatable when cold like coffee and beer, and sweet things all the sweeter like ice cream. Sometimes though you want those flavors, bitter and all. Still others are best between the two, at room temperature, like cake, and of course some foods taste good whether hot or cold, like fried chicken for instance. | [
"Conditioned taste aversion is the only type of conditioning that only needs one exposure. It does not need to be the specific food or drinks that cause the taste. Conditioned taste aversion can also be attributed to extenuating circumstances. An example of this can be eating a rotten apple. Eating the apple then i... |
"Blacks" or "African-Americans"? | You might split the difference and go with Black Americans. No one is likely to get mad about that sort of thing in an undergrad paper so long as you're making a good faith effort. Also the general trend is to [capitalize the B in Black Americans](_URL_0_) these days, though that is a hot topic. | [
"African Americans (also referred to as Black Americans or Afro-Americans) are an ethnic group of Americans with total or partial ancestry from any of the black racial groups of Africa. The term typically refers to descendants of enslaved black people who are from the United States.\n",
"Black and African America... |
does massage really work to get rid of the 'knots'? what are the knots and why do you sometimes feel worse after a deep tissue massage? | Actual scientific explanations of knots:
_URL_0_
_URL_1_
_URL_3_
and massage:
_URL_2_
**ELIF version-** "Knots" are caused by a damaging muscle/connective tissue combined with swelling/sensitivity from the following immune response. From the papers above, massage often doesn't work in controlled trials, massage hasn't been conclusively shown to increase blood flow/removal of toxins/introduction of __ by a significant amount, soreness has nothing to do with lactic aid (and lactic acid is not even removed faster via massage vs cool-down stretching, and lactic acid injections actually help recover from fatigue faster), and massage doesn't help muscle flexibility/alignment/etc more than stretching.
Massage *has* been shown to decrease stress/stress hormone levels, help with relaxation, and a lot of other "it's all in your head, but what's in your head actually really really matters" factors.
You sometimes feel worse after a deep tissue massage because the mechanical stress damages other cells and pain is stressful.
Source: biomedical engineer, microbiologist/geneticist, neuroengineer, and apparently someone willing/able to spend two+ hours browsing google scholar for the hell of it. | [
"BULLET::::- Friction massage is said to increase mobilization of adhesions between fascial layers, muscles, compartments and other soft tissues. They are thought to create an inflammatory response and instigate focus to injured areas. A 2012 systematic review found that no additional benefit was incurred from the ... |
why is the australian dollar so weak against the british pound? | No, the Aussie dollar is pretty strong against the pound, currently sitting at 55 pence.
It is always a mistake to compare currencies absolute values, as these are a result of history. The difference in this case is because Australia switched to decimal currency back in 1966, and with currency being more valuable back then, they chose to make the new dollar equal to 10 shillings, or half the previous non-decimal currency, the Australian Pound. England changed to decimal currency in 1971, and retained the name 'pound' for their currency - which meant that they started with their decimal pound equal to 20 shillings.
With ups and downs since then the relative values of the Australian dollar and the English Pound hasn't really changed. | [
"The value of the Australian pound remained tied to the pound sterling. Inflation in Australia thus increased, less than in Britain, but more than in the United States. The case for a central bank was increased by the need for the government to cut spending after the war to reduce its debt. Commonwealth Bank Govern... |
Why does water that you carry feel heavier than water that you consumed? | When you drink it, the water is at the near center of your body, in your backpack it's not. There i more support at the center of your body so it feels lighter. Carrying it on your back also requires a posture that is harder to maintain and thus requires more energy and may exhaust your muscles more. | [
"The buoyancy force is equal to the weight of the body, in other words, the mass of the body is equal to the mass of the water displaced by the body. This adds an upward force to the body by the amount of surface area times the area displaced in order to create an equilibrium between the surface of the body and the... |
How certain are we of what year it is? Were there every any disagreements, like during the Dark Ages or afterwards, of the exact year? | Well, it's one thing to be off by a day or so, but by a year? That's a massive mistake for an entire population to make. But it wasn't until 525 AD that the AD numbering system began. And there are a couple discrepancies in figuring out when Jesus was born, to start counting. The gospels (for those who take them literally) describe two things that are mentioned elsewhere and let us date it. Matthew says that after Jesus was born, King Herod (the Great) is still alive, because he massacred children in an attempt to kill Jesus. (There's no evidence of any such massacre, though Herod was very bloody). Luke says that Mary and Joseph were in Bethlehem only because of the Census of Quirinius. (That they would have to travel to Joseph's ancestral home of Bethlehem instead of staying in Nazareth makes no sense. The Romans would never have demanded that, and it's completely impractical.) ANYWAY... King Herod died in 4 BC, and the Census took place in 6/7 AD. So one, if not both of these is wrong. And if either of them is right, then our AD 1 is wrong. Basically, though the modern consensus is that Jesus was a real person, any attempt to figure out what year he was actually born in is a shot in the dark. So in that sense, we don't know if this really "should" be 2012 or not. But since 525, when they started the AD system, no. No, there's no doubt that it's been kept correctly. And there are enough documents and histories for the previous thousand years that when we label something "44 BC" we're confident that they didn't miss a year.
tl;dr- Year 1 AD is arbitrary, and frankly just a guess as to Jesus's birth year, but accepting that, yes, this is 2012. | [
"Year 229 (CCXXIX) was a common year starting on Thursday (link will display the full calendar) of the Julian calendar. At the time, it was known as the Year of the Consulship of Severus and Cassius (or, less frequently, year 982 \"Ab urbe condita\"). The denomination 229 for this year has been used since the early... |
meta plea to eli5 about the upcoming elections. | Also, can we have active moderation? ELI5 will have more and more questions of the "push-poll" variety as the election nears. It will become unusable if half of the posts are "ELI5 why Mitt Romney hates gay babies" and "ELI5 how President Obama can hold office if he's a secret Kenyan Nazi?" | [
"In 2003, the IOP launched the National Campaign for Political and Civic Engagement, working collaboratively with other schools and organizations across the country to engage young people. The IOP also conducts research and surveys into the political views of America's young voters. In addition, the Institute offer... |
why does it take minutes to take money from my bank account but days to put it back? | What takes minutes is the authorization for somebody to take money from your account, not the time for the money to actually be removed from yours and into theirs. However, once a transaction has been authorized, your bank will show your account as having that much less money, so it can seem like it is final to you (and for most intents and purposes, it is).
For money incoming into your account, it's the same thing, but you see the other side of the story. Money is authorized to be removed from somebody else's account, though the money isn't actually moved to your account for a while.
Returns and other things often suffer another delay before this as the system that processes returns to accounts often isn't "run" until the end of the day, (or even once every few days/a week in many cases).
| [
"Once a current account has been opened with a new bank or building society, the Current Account Switch Service will transfer all the activity relating to the old account to the new one. That includes moving incoming and outgoing payments, and transferring the account balance, as well as closing the old account. An... |
what is "doping" in cycling and why is it illegal? | Doping in cycling typically refers to the use of any kind of performance enhancing drug. The actual term doping, I believe, comes from the term "blood doping" which means to artificially increase your red blood cell count. A lot of cyclists that have been caught cheating recently have been using something called EPO which allows your body to produce red blood cells faster and to keep the levels of red blood cells higher than normal. This is important to cyclists because red blood cells transport oxygen to and from muscles so the more red blood cells the faster this can happen. The reason this is illegal in cycling is that it gives an artificail advantage to those that use it. | [
"\"The sport of road-race cycling (and it may not be the only one) is like an alcoholic, refusing to accept that it has a problem, as long as it drinks in secrecy. That fact was shamefully proved once again this week when the sport's governing body — the International Cycling Union (UCI) - forced the 1999 Tour to a... |
why have desktop app stores not gotten similar development as mobile app stores? | Developers don't like app stores. They take a 30% cut, restrict what your app can do, make you wait to get your app released, don't allow upgrade versions, etc. You don't get direct access to your customer, you can't get their email to try and sell them more crap.
On most mobile devices developers don't have any choice but to use the app store. Or if they can work around it (Android) it not worth the effort because everybody expects the apps to be in the app store.
On the desktop, users expect to get applications directly from the developer, so there is no reason to put up with the downsides of the app stores. | [
"Most companies have acknowledged the potential of Mobile Apps to increase the interaction between a company and its target customers. With the fast progress and growth of the smartphone market, high-quality Mobile app development is essential to obtain a strong position in a mobile app store.\n",
"The launch of ... |
How does a single membrane in an earphone generate multiple frequency sounds at the same time instant? (For example, high hats with vocals) | When a complex sound or mixture of sounds is heard, there is really only one wave that hits your ear. The waves of sound in the air are able to interfere both destructively and constructively, and the function of the final wave is the sum of those of all the individual waves. The result is not a series of waves traveling to your ear in parallel but a single wave describing the pattern of vibrations in the air corresponding to peaks and troughs of various amplitudes and periods. A graphical representation of the wave can be seen on a computer or phone with a simple oscilloscope program or "sound wave" app. One way of thinking of it is getting the air that is already distorted by the wave produced by one tone and further distorting it in the same way flat air would be distorted by the second tone. Analogue media like record players and gramophones record this final wave by electronically or mechanically translating the motion of a membrane into inscriptions on a surface or in the case of tapes recorders, variations in magnetic charge along a length of tape. They can then translate this back into the motion of an oscillator and reproduce the same complex wave that they originally "heard" within their technical limitations.
All your earphones have to do is to replicate the vibration in the air that would have reached your ear if your ear were near the recording device. It simply vibrates according to the electrical signal in approximately the right way to produce this complex wave that contains all the notes of a chord, all the sounds of a street, etc. What is really amazing is that your brain can pick apart the wave into its constituent sounds and recognise them in isolation.
I really recommend using an oscilloscope or something similar to look at sine waves, saw waves and and square waves to see how waveform affects sound volume tone colour and pitch. Also, try multiple sounds at once. One octave of separation means the notes' frequencies are in the ratio of about 1:2. Compare tuned sounds to percussive sounds. It' really fun and helps you undesirable how what you hear is related to the vibrations in the air. | [
"If two sounds of two different frequencies are played at the same time, two separate sounds can often be heard rather than a combination tone. The ability to hear frequencies separately is known as \"frequency resolution\" or \"frequency selectivity\". When signals are perceived as a combination tone, they are sai... |
nowadays we are starting to use more paper products than plastic (straws , bags etc) will this his not create a problem in the future because paper is made out of trees ? | I think the idea is that we can farm trees, wood is a renewable resource. Also so long as this wood isn’t burnt and instead is turned into paper, it should in theory soak up CO2 from the atmosphere and leave us better off. | [
"A 2007 report into shopping bag alternatives noted that paper bags were less environmentally friendly than plastic bags due to a higher carbon footprint. Similarly, cotton bags were unsuitable due to the pesticides used and high volume of water needed to create them. The \"greenest\" option was using recycled plas... |
how can only one jet engine fly a twin engine airplane for hours after the other has shut down? | For large passenger jets, the aircraft is designed to be able to fly with one engine shut down (an “in-flight shutdown, or IFSD). That’s why they’re designed with at least two engines.
There’s a concept called ETOPS (Extended Twin Engine Operations, or, more humorously, “Engines Turn Or People Swim”) which means that if a two-engine aircraft has a single engine shut down, statistically-speaking it is a good bet that the other engine will NOT shut down by an independent cause within a certain number of minutes. How many minutes depends on things like engine reliability data, maintenance records, and maintenance crew experience. A twin-engine commercial aircraft is allowed to fly a certain route only if diversion airports are within the range of the aircraft, flying on a single engine, for less time than the ETOPS time limit at all points during the route.
Modern twin-engine aircraft are ETOPS certified for quite a large number of minutes, making long flight times after an engine failure (thankfully) possible.
Hope this helps. You can always do a search for ETOPS to get more info.
Edits: minor grammar | [
"Early American twinjet designs were limited by the FAA's 60-minute rule, whereby the flight path of twin-engine jetliners was restricted to within 60 minutes' flying time from a suitable airport, in case of engine failure. In 1964, this rule was lifted for trijet designs, as they had a greater safety margin.\n",
... |
It's generally understood that a good deal of dangerous animals have bright colors to act as a "warning" (poison dart frogs, coral snakes, etc.), but aren't most of their natural predators colorblind? Wouldn't this diminish the effectiveness of this defense mechanism? | Birds (which are common predators of insects and frogs) have some of the best vision and color detection of any animal. If they were colorblind we wouldn't have colorful birds (color helps them mate and show dominance), because the duller colored ones would be less likely to be eaten by predators, and thus color would have no evolutionary benefit.
Snake (another main predator of frogs) vision varies greatly, with most not being able to see very sharply, but they are able to track movement, and others use smell, heat, or vibration to track prey. Many brightly colored animals will also have a scent that's detectable, and serves as a warning.
EDIT: A letter | [
"Poisonous species often use bright colouring to warn potential predators of their toxicity. These warning colours tend to be red or yellow combined with black, with the fire salamander (\"Salamandra salamandra\") being an example. Once a predator has sampled one of these, it is likely to remember the colouration n... |
the whole controversy around goldman sachs. | Read Griftopia. Sorry, it's not that simple. That's why it went on for so long. | [
"Goldman has been criticized in the aftermath of the financial crisis of 2007–2008, where some alleged that it misled its investors and profited from the collapse of the mortgage market. That time in Goldman's history brought investigations from the United States Congress, the United States Department of Justice, a... |
What causes a gun barrel to rise when I shoot? If I hang upside-down and shoot, will the barrel "rise" away from the anchor point (i.e. my feet) or away from the source of gravity (i.e. the Earth)? What would happen if both are absent (i.e. in space)? Or is something else going on? | The bullet doesn't leave along the line that passes the center of the gravity for the gun. Because of this, the device will experience a torque from the gas that pushes back in the firing chamber, and it will attempt to begin rotating, which is what you should see in space. | [
"The pivoting part that supports the cylinder is called the crane; it is the weak point of swing-out cylinder designs. Using the method often portrayed in movies and television of flipping the cylinder open and closed with a flick of the wrist can in fact cause the crane to bend over time, throwing the cylinder out... |
what makes an expensive product so expensive? is it more related to the brand, or the materials? | It's really depends on the product. Some are expensive because of the brand, some are expensive because of msterials. But both and neither can apply.
The better question is what product are you refering to? | [
"Some luxury products have been claimed to be examples of Veblen goods, with a positive price elasticity of demand: for example, making a perfume more expensive can increase its perceived value as a luxury good to such an extent that sales can go up, rather than down.\n",
"This situation is derived by the desire ... |
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