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please explain the isis iraq situation. | Ohh man its complicated..
So ISIS is the Islamic State of Iraq and Syria. They have been active mainly in Syria fighting against Bashir Al Asad, but have been pushed back there (out of Alepo and denser urban areas) by more moderate rebels (who the US ostensibly supports). Recently they cashed in on the Iraq side of their organization and captured several cities there in rapid succession meeting little or no resistance from Iraqi security forces (trained and supplied by the USA) which freaked everyone out. They got a ton of gold and cash from banks and military equipment left behind by the Iraqi security forces.
Now weird shit is happening. Iran is offering to send republican guards to Iraq to fight ISIS and the US is considering bombing ISIS in Iraq and Syria. The Kurdish autonomous region has sent soldiers in to hold off ISIS and capture a few cities... basically its the penultimate strange bedfellows type of situation where enemy factions are coming together to try and stop this army who showed up from nowhere and displayed shocking capability. Not a good spot for US regional interests whatever we do will be no bueno. Really points out weakness and division in the Iraqi gov. Basically no one saw it coming.
Side note ISIS was rejected by Al Queda for being "too extreme"
There are rumors of old Iraq army brass from the Saddam days working with them.
The danger is that Iraq will devolve into a full on ethnic civil war which combined with Syria's war could easily become the biggest genocide of this century.
This is what I have gathered feel free to fact check or ask me and Ill explain to the best of my ability. | [
"In early 2014, ISIL drove Iraqi government forces out of key cities in its Anbar campaign, which was followed by the capture of Mosul and the Sinjar massacre. The loss of control almost caused a collapse of the Iraqi government and prompted a renewal of US military action in Iraq. In Syria, ISIL has conducted grou... |
How do people determine the tilt of a planet of direction is relative in space? | We define the ecliptic as the plane that contains the Earths orbit around the sun. We define the tilt of a planet as the angle between the normal direction of the ecliptic and the axis of rotation of the planet. | [
"Orbital inclination is the angle between a planet's orbital plane and another plane of reference. For exoplanets, the inclination is usually stated with respect to an observer on Earth: the angle used is that between the normal to the planet's orbital plane and the line of sight from Earth to the star. Therefore, ... |
[Book Request] I don't see any books for the Reconquista on the book recommendation list | Point of clarification. What are you looking for when you say "a general history of *the Reconquista*?" Although the underlying crusade ideology is there for the Christians, and as time wore on Muslims definitely realized their al-Andalus (by then comprised of many little kingdoms) was losing ground to a bunch of Christians, overall it's hardly a unified campaign or even always primarily making progress. There are larger swathes of time where territory either isn't changing hands, or already conquered territory is being filled in (most of the Iberian interior was fairly empty), or Christian and Muslim statelets alike are batting away at each other, making and breaking alliances. "Reconquista" is kind of a convenient name, but the point is, it's not really separate from the political and social history of later medieval Iberia.
Is that what you're looking for? Or are you looking for more, military history-style accounts of battles, sieges, civil wars? | [
"A book has been published (written in Spanish) under the auspices of the Ajuntament De Carlet, Valencia, with the title \"Amparito Roca, El Pasadoble Del Mestre Texidor\". It contains biographical material and commentary on the works of Texidor with a catalogue and discography. The text is by Angel Valero Garcia.\... |
Why did CPUs stopped at around ~3-4GHz? | See:
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_URL_1_ | [
"Both the 6400 and 6600 CPUs had a cycle time of 100 ns (10MHz). Due to the serial nature of the 6400 CPU, its exact speed was heavily dependent on instruction mix, but generally around 1 MIPS. Floating-point additions were fairly fast at 11 clock cycles, however floating-point multiplication was very slow at 57 cl... |
What festivals did the romans celebrate (pre-christianity)? | The Romans celebrated plenty of festivals, and I'll highlight a couple of the more important ones for you.
* **Lupercalia:** This is possibly the most famous Roman festival, along with Saturnalia. It was celebrated during February (13-15) and it was a celebration of the health and fertility of the city of Rome. Probably the most famous ceremony of this festival is when two young men run around the Palatine clad in goatskin, holding strips of the skin of animals sacrificed earlier in the day. Crowds gathered to watch and women hoped to be whipped with these skins, believing it would make them fertile. An interesting anecdote occurred in 44BC, when the then-consul Mark Antony refused to participate in this Lupercalia tradition.
* **Saturnalia:** Along with Lupercalia, this is a very famous Roman festival. Unsurprisingly, this was a festival honoring the god Saturn and was originally celebrated on December 17th, the solstice, but over the centuries the festivities spread between the 17th and 23rd. Everyone loved this festival, especially servants because on this feast day, their masters would wait on them in a fun (ish) role reversal. Also, gambling was permitted during these festivities, but was back to restricted for the rest of the year.
edit; forgot a word! | [
"A major source for Roman holidays is Ovid's \"Fasti\", a poem that describes and provides origins for festivals from January to June at the time of Augustus. Because it ends with June, less is known about Roman festivals in the second half of the year, with the exception of the Saturnalia, a religious festival in ... |
why is if more harmful to the human body to be exposed to freezing water than it is to be exposed to air of a similar temperature? | Heat generally transfers from molecule to molecule. More molecules means faster heat transfer. The amount of molecules in a given volume is called density. Generally speaking, the denser a substance is, the better it is at transferring energy. Water is much denser than air. So, heat energy from your body will flow faster into water than it will into air. That's why cold water is more dangerous than cold air at the same temperature. The water will "suck" the heat out of you much faster than the air | [
"Heat is lost much more quickly in water than in air. Thus, water temperatures that would be quite reasonable as outdoor air temperatures can lead to hypothermia in survivors, although this is not usually the direct clinical cause of death for those who are not rescued. A water temperature of can lead to death in a... |
How and when were tanks, semiautomatic weapons and planes started being deployed in warfare? | The Second Industrial Revolution happened.
Generally considered to have started in 1870, the Second Industrial Revolution saw the development of a wide range of technologies, manufacturing techniques and chemicals that made many of the weapons and technologies of the First World War possible.
More efficient means of producing steel (and higher quality steel as well), the internal combustion engine, electrification, pneumatic tires, highly efficient steam engines for ships, increased mechanisation of manufacturing including the mechanical manufacturing of parts for manufacturing machines making them cheaper and standardising them, incandescent lightbulbs, increased production of petroleum, increased understandings of thermodynamics and metallurgy, ball bearings, fertilisers, bicycles, the telephone and much much more emerged from the is period.
You can probably see how these technologies contributed to the First World War, better steel coupled with better steam engines led to the expansion of ironclad ships and ultimately the first modern modern battleship HMS Dreadnought which kicked off a naval arms race. Developments in manufacturing coupled with increased understanding of metallurgy and new chemicals allowed bigger, more powerful guns to be created. Internal combustion led to powered flight and then the land ship more commonly known as the tank. The development of fertiliser cannot be underestimated as well. By being able to artificially replenish the nutrients in soil, crops could be reason in the same fields leading to an increase in food production which increases supply and in turn drives down prices. This allows nations to feed their people and keep their armies fed. It also allows them to have bigger armies and better manufacturing allows them to equip their armies with newer and bigger weapons.
This is an extremely vast topic and deserves a much more in depth answer then I have time to give but I'm sure a resident expert will be along shortly to provide a far better answer then this. | [
"In post-Cold War conflict, the resurgence of expeditionary warfare has seen the emergence of gun-armed wheeled vehicles, sometimes called \"protected gun systems\", which may bear a superficial resemblance to tank destroyers, but are employed as direct fire support units typically providing support in low intensit... |
what is modern art and what determines the price? | Whatever the artist feels he is owed is weighed against public appraisal. It’s supply and demand, but on a very intimate scale, that determines the price. That is to say, the worth of the piece is the highest value a person wishes to pay. If the artist accepts, then that will be the price at which it is sold. | [
"Components of a work of art, like raw stone, tubes of paint or unpainted canvas, in general have a value much lower than the finished products, such as a sculpture or a finished painting. Also, the amount of labour needed to produce an item does not explain the big price differences between works of art. It seems ... |
why is depression such a pervasive theme throughout reddit? | Reddit is a fairly liberal place that likes to focus on fighting for marginalized causes. Depression and mental health are largely ignored in general society and affect a huge number of people, so naturally Reddit wants to talk about it. Also, since Reddit is an anonymous community, it is much easier to talk about our problems when we are anonymous than in person. | [
"In this way, the depression can be traced back to a demand for perfection from which a person is deducing their own worthlessness, from which they are in turn deducing the horribleness of what happened.\n",
"Scholars Dhir et al. discuss the potential for depression in relation to social media use and FOMO. They ... |
why are rabbits associated with sexual things like playboy? | Rabbits have a reputation of breeding prolifically, which leads to their reputation of having sex very often. | [
"Rabbits are often used as a symbol of fertility or rebirth, and have long been associated with spring and Easter as the Easter Bunny. The species' role as a prey animal with few defenses evokes vulnerability and innocence, and in folklore and modern children's stories, rabbits often appear as sympathetic character... |
difference between memory and ssd | Memory typically refers to RAM (random access memory) where as SSD (solid state drive) refers to storage.
Easiest way to know the difference is think of RAM as a work table and SSD or other storage device like a hard drive as storage cabinets.
If you want to work on a project, you can only use as many tools (aka apps) as you have room on your work bench. If you run out of room on your work bench but need something else, you'll have to put something away in the cabinets and search for the new thing you need, pull it out and put it on the work bench to use. The bigger your work bench, the more stuff you can use at one time. The bigger the cabinets, the more stuff you can have in total, whether using it or not.
Things like editing software take up a lot of room on the work bench. Games can too. Games also take up a lot of room in your storage cabinet. Things like pictures are tiny and take up little room on the work bench, but can add up in your storage cabinets if you have enough of them | [
"While both memory cards and most SSDs use flash memory, they serve very different markets and purposes. Each has a number of different attributes which are optimized and adjusted to best meet the needs of particular users. Some of these characteristics include power consumption, performance, size, and reliability.... |
how does mass hysteria work and how can it manifest physical symptoms? | It's pretty much a huge case of fomo with the placebo effect. You see a bunch of people doing something and your mind thinks that the might be something triggering it that effects you so you begin to physically manifest something like an uncontrollable urge to dance or some kind of sickness | [
"In sociology and psychology, mass hysteria (also known as \"mass psychogenic illness\", \"collective hysteria\", \"group hysteria\", or \"collective obsessional behavior\") is a phenomenon that transmits collective illusions of threats, whether real or imaginary, through a population in society as a result of rumo... |
why does hard cheese which has been maturing for years have a sell-by date of only a few weeks? | It's been cut.
As long as the outside of the cheese is entirely the outside of the cheese (the rind), the cheese will have a substantial shelf life. As soon as you cut it, opening up the more moist interior to oxidation, mold, and bacteria, it has a shelf life. That being said, some cheese (like parmigiano reggiano) will, in my experience, simply get rock hard when kept for too long, rather than spoiling in some way that makes them inedible. | [
"Harder cheeses have a lower moisture content than softer cheeses. They are generally packed into moulds under more pressure and aged for a longer time than the soft cheeses. Cheeses that are classified as semi-hard to hard include the familiar Cheddar, originating in the village of Cheddar in England but now used ... |
why is video ram (like gddr5) so much faster than regular ram (like ddr3 or ddr4)? | GDDR, similar to GPUs are very parallel in design.
So while you might have "dual channel" or "triple channel" memory slots on a system board, GDDR memory can be arranged into 8, 16, or 32 parallel channels on the graphics circuit board. This yields nearly linear performance gains in memory throughput since memory chips are accessed in parallel. For this to work efficiently, this requires that the graphics chip itself is also designed to be massively parallel (unlike CPUs) with hundreds (or thousands) of cores / shader processing units that are all loaded up between ticks and all fired simultaneously on the clock tick.
| [
"BULLET::::- Clock Speeds: This is the clock speed that the graphics core and video RAM run at; they do not need to be the same. The faster the clock speed, the more the graphics core and/or video RAM can accomplish in a second. All modern video cards use DDR SDRAM, which, for all performance issues, is twice as fa... |
in david attenborough documentaries, how do they get the camera inside each respective insect/animals home? | If you have the DVD/Blu-Ray sets, watch the behind-the-scenes extras.
These nature photographers spend months and months working to catch the perfect moment (really makes the viewer marvel and appreciate their contributions to public knowledge). | [
"Several special filming techniques were devised to obtain some of the footage of rare and elusive animals. One cameraman spent hundreds of hours waiting for the fleeting moment when a rare frog, which incubates its young in its mouth, finally spat them out. Another built a replica of a mole rat burrow in a horizon... |
What is the price difference between geothermal energy and fossil fuel energy? | It really *really* depends on where you're trying to get geothermal energy from. In Iceland, which has tons of volcanic activity and gets all its electricity from geothermal, electricity prices are about half the cost in other Nordic countries.
However, in almost every other part of the world, you'd have to drill 5-10 times deeper than in Iceland to reach rock hot enough to run a steam turbine. The extra cost, plus the difficulty in getting water in and steam out of such a deep hole, make geothermal energy impractical.
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"Geothermal power is considered to be a sustainable, renewable source of energy because the heat extraction is small compared with the Earth's heat content. The greenhouse gas emissions of geothermal electric stations are on average 45 grams of carbon dioxide per kilowatt-hour of electricity, or less than 5 percent... |
Help identifying a Japanese battle flag from WWII | I can't read all of it--the vertical text on the sides is quite difficult and I will leave it to somebody else. But the text on the top 国報身 献、is a wartime slogan that means something like 'serve the country, give up one's body' and the name of the soldier on the bottom horizontal text, I think, is Hisanaga Takeshi. It also gives the family name of the Lieutenant General of his unit (I'm assuming), which was Tominaga and would probably help in locating his family. It's also dated Showa 18 or 1943. | [
"BULLET::::- Finding the red in the national insignia adopted in June 1943 for its military aircraft could cause confusion with Japanese markings during combat, the United States adopts a new marking consisting of a white star centered in a blue circle flanked by white rectangles, with the entire insignia outlined ... |
how come the military is "always recruiting" and are all countries like this? | People are always leaving and moving up even when an army downsizes. Ergo there are always needs for replacements at the bottom.
Now you may not get to be a helicopter pilot. There is always need in the infantry | [
"The most popular age group to recruit for the military is the youth population, because many youth are opting out of going to college because of the economic times and financial positions. \"The recruiting process involves national and local advertising to efficiently supply information on a widespread basis; info... |
how do people doing gymnastics always land on their feet? | They spend years failing to land on their feet. Its an enormous amount of practice, and even then they aren't always perfect. | [
"Gymnasts are expected to land cleanly, with no hops or steps, and within a set landing zone on the landing mat. They must also demonstrate good technique and execution in the actual vault. Falling or stepping on landing incurs deduction, as will lack of height off the table, or distance from the table.\n",
"Foot... |
i'm an adult. why do i always dream about school? | You can think of it as a very, very mild form of Post Traumatic Stress Disorder (PTSD).
Basically, you dream of it because you went through it. If someone does go broke and lives on the streets or get very sick enough that it impacts their life, they will probably have nightmares about being back in that situation. | [
"You can learn a lot about a person from his dreams. What we dream is a reflection of who we are. It is the measure of our aspirations and goals, and of those values we hold dear and place above all else.\n",
"This group of teenagers will discover that they have more in common than they imagined, they are united ... |
Would it be inaccurate to say that in general, the common people of modern first world countries eat better than medieval European royalty? | Actually, the quality of the cuisine was generally pretty good, if you're talking about how good it would have tasted. As (and it's embarrassing to admit) a Medieval food enthusiast, I can personally vouch for how tasty the food was. It was generally very similar to the modern foods of whatever country you're looking at. Pasties have been around, in one form or another, for a *very* long time. The major documents like the Forme of Cury were recorded because they were the king's, and so forth, so we know less about the smaller manors (much less about food that wasn't being consumed by VIPs), but they probably ate similar foods.
The flavoring ingredients, the spices and herbs, were imported from all over, and they would have been dried, so they'd keep a long time. Vinegar and oil keep well, too. And there was probably a bigger variety of spices back then! As (I think) a status symbol, courtly food often called for very exotic spices like cubebs, imported from (I think) Madagascar, and grains of paradise, from Ethiopia, which are very hard to find nowadays. Cinnamon and ginger, brought from the East, were especially popular.
As for variety in the diet, royalty actually did pretty well with that, too. There were large varieties of meats and fish available. Hunting was a regular occurrence and people ate, if anything, more varieties of meat than they do now. Because of religious days, fish was mandated many, many days of the year, and fish is pretty good for you. Apparently fish was called for so often that there are books with writing in the margins that say "I am so sick of fish," and some recipe books suggest that beavers, since they lived in the water, could be considered fish.
Vegetables were also pretty varied within the diet, although more things are available now. Again, the kings and queens would have had large gardens to supply whatever was in season. Medieval recipes don't include as many vegetables as modern ones, but they were there. Medieval palates seem to have loved sweetness, as a lot of dishes, sweet and savory, include fruit.
There was also cheese and other dairy. Cheese tends to keep pretty well. Different countries have different kinds of cheese, and hard cheeses keep better than the others. Again, since stuff was consumed in quantity, I would imagine spoilage wasn't an issue with stuff like milk and cream.
There were also plenty of starches - there was lots of bread. As a side note, whole grains were actually good for medieval teeth, as they have a scouring effect on the teeth.
Since we're talking about royalty, meat/fish spoilage wouldn't have been an issue, as the meat and fish would be consumed right away in large quantities. Plus, there was available game year-round. Certain vegetables would be kept in root cellars, etc, and they did find ways to keep things from spoiling (after all, it's not like rotten fruit or veg tastes very good).
In general, we know more about nutrition than people did back then, so we are more conscious of bringing variety into our diets, whereas Medieval royalty was more about flavor and flash (banquets could, for example, feature porpoise as a dish, no doubt served whole as a dramatic platter). Because the more expensive things like meat, cheese, etc taste better, the diet was probably not as balanced between meat and non-meat as it is now.
Still, the Medieval palate had some interesting tastes, and I find it pretty enjoyable to connect with history in such a sensory way. If you're interested, I can post some recipes, etc.
edit: clarity | [
"European consumption of meat remained exceptional by world standards, and during the period high levels generally moved down the social scale. But the poor continued to rely mainly on eggs, dairy products, and pulses for protein. Often they did better in the less populated regions, where wild game and fish could s... |
how can someone who lost all movement from below the neck breath without aid? | In some cases they absolutely cannot, and must use a machine such as an "iron lung" or respirator.
In other cases, although their voluntary nerves aren't working, the other nerves that run automatic systems are still in good shape. | [
"It is essential that rescue breathing be continued without pause until the paralysis subsides and the victim regains the ability to breathe on their own. This is a daunting physical prospect for a single individual, but use of a bag valve mask respirator reduces fatigue to sustainable levels until help can arrive.... |
why do adolescent girls seem to be more obsessed with boy pop stars (think justin bieber, boy bands, the beatles, etc.) than adolescent boys are obsessed with female pop stars? | Boy pop stars are marketed to girls.
Girl pop stars are marketed to girls. | [
"Girls gravitate towards \"music, clothes, make-up, television talent shows and celebrities\". As young children are more exposed to and drawn to music intended for older children and teens, companies are having to rethink how they develop and market their products. Girls also demonstrate a longer loyalty to charac... |
Does Crossing-Over in Meiosis result in new genes? | It's not clear from your question whether you mean new alleles ("versions" of genes) or whole new genetic loci (sections of the chromosome), but the answer is yes in both cases!
[Crossing-over](_URL_0_) happens anywhere along the chromosome, both within and between genes. For this reason, after meiosis one gene can end up with its first section from one original chromosome and the rest from its [homologous chromosome](_URL_1_). If one allele has a mutation in the DNA code in the first half and the other has a mutation in the second half, meiosis can create a new pair of alleles: one with *both* mutations and the other with none.
In this way, brand new alleles can be created during crossing over by mixing up small DNA code changes that mutated independently in different ancestors. Cool!
You can also end up with entirely new genetic loci through [unequal crossing-over](_URL_3_). Normally homologous chromosomes line in the correct alignment, where each gene on one chromosome matches up with the same one on the other chromosome. But sometimes there are mistakes, especially if there are similar or repetitive DNA sequences on multiple locations on the chromosome. If this happens, you can get one chromosome to give up a chunk of DNA without getting the corresponding chunk back from its partner. This can cause [gene duplication](_URL_2_) in the recipient chromosome.
A cell inheriting the chromosome that lost one or more genes is likely to have problems, but ones that got the extra gene will probably be just fine. In fact, having an extra copy of the gene can be really valuable for evolution, as one copy can be mutated to have a new function without losing the original functionality in the duplicate. | [
"Crossing over (genetic recombination) and random segregation during meiosis can result in the production of new alleles or new combinations of alleles. Furthermore, random fertilization also contributes to variation.\n",
"If \"terminal fusion\" (restitutional meiosis of anaphase II or the fusion of its products)... |
How many mass extinctions were there, and how do we know? | Your number is correct and we know different ways.
I note that animals (and plants) go extinct all the time but in order to be a mass extinction event the extinctions have to be within a similar time frame (happen over the same span of time which isn't just instant but can cover thousands of years - such as the current one in which other plants and animals are becoming extinct because of the growing human population).
We know because of fossil records showing a massive number of some species then "poof" suddenly none..
As well we can study DNA to note bottlenecks of populations. | [
"The first of five great mass extinctions was the Ordovician-Silurian extinction. Its possible cause was the intense glaciation of Gondwana, which eventually led to a snowball earth. 60% of marine invertebrates became extinct and 25% of all families.\n",
"There have been at least five mass extinctions in the hist... |
why arent any saudi royals on the top billionaire lists? are they not filthy rich from oil? | Those guys are also not particularly transparent. Since Saudi Arabia is an absolute monarchy, the country's budget and state investment funds are also the royal family's own wallet, whereas "conventional" billionaires own far more easily detectable corporate assets. | [
"Nasser Ibrahim Al-Rashid (born 1939) () is a Saudi businessman. He is reputedly an influential advisor to the Saudi royal family and a US dollar billionaire. However he is not included in the \"Forbes\" list of the world's richest people as his personal wealth, like that of many Saudi insiders, cannot be assessed ... |
why does it matter that young people don't vote? | Broadly speaking, young people not voting shows there is a lack of engagement. This can mean they don't feel like anything will change, or can change.
This matters because for democracy to function properly (i.e. have checks and balances, a knowledgable electorate etc.) people actually have to give a damn. And what many young people don't realize is, they can make a difference.
Most places, 18 year olds can vote. These are people in university/college, or starting in the work force. Governments play a major role in their lives (i.e. setting tuition levels and stuff like that), so if they have a vested interest in the outcome of the elections. | [
"One reason cited for why children and the mentally disabled are not permitted to vote in elections is that they are too intellectually immature to understand voting issues. This view is echoed in concerns about the adult voting population, with observers citing concern for a decrease in 'civic virtue' and 'social ... |
I am a Roman equite from the age of Augustus examining Rome during the reign of Constantine. What has changed most noticeably? Is the new Rome even recognizable to me? | ^I'm ^not ^sure ^what ^you ^mean ^by ^"examining ^Rome". ^If ^you ^mean ^something ^like ^walking ^through ^the ^city ^of ^Rome, ^this ^would ^be ^my ^answer:
& nbsp;
Rome has changed massively between the reign of Augustus (27 BCE - 14) and that of Constantine (306-337). Most major monuments are completely new to you. A short list of prominent examples:
& nbsp;
*First century*
* The Colosseum would stand where houses stood during your time, it was built by the Flavian emperors (69-96)
* Several new forums would have been added near the Forum Romanum and the already familiar forums of Caesar and Augustus
* The Arch of Titus, celebrating Rome's victory in the Jewish Revolt
*Second century*
* The Pantheon would not be the one you know, built by Agrippa, but a completely different (and more impressive) building built by Hadrian. Surprisingly the original inscription remains
* Trajan's Market
* The Column of Trajan depicting victories in Dacia, an area that didn't yet belong to the Roman Empire in your time
* The Column of Marcus Aurelius
* The Temple of Faustina and Antoninus Pius on the Forum Romanum
*Third century*
* The Aurelian Wall, a new city wall
* The enormous Baths of Diocletian
* The likewise enormous Baths of Caracalla
*Fourth century (up until the end of Constantine's reign)*
* The Old St. Peter's Basilica would be under construction, a church being built by emperor Constantine for a religion you've never heard of
* The Arch of Constantine, celebrating a victory in the civil war against Maxentius
* The Basilica of Constantine and Maxentius on the Forum Romanum
*Some other differences*
* The coins have largely different names from the ones you knew, they're also heavily debased compared to the Augustan age
* People from all over the empire are citizens now due to the Edict of Caracalla in 212
*Some similarities*
It may surprise you to learn that some things would be very much recognizable to you. For example:
* The number of people in Rome would be roughly the same, although Augustus' age was before the population reached a peak while Constantine reigns after it reached its peak.
* The Circus Maximus has been improved upon, but has kept most of its original design
* The Curia Julia, where the Senate debates on the Forum Romanum is pretty much the same building you know
* The Theatre of Pompey
* Emperors are still calling themselves "Caesar" and "Augustus", even though no-one of the Julio-Claudian family remains
* The city of Ostia is probably still Rome's dominant harbour, although it is in heavy competition with Portus (which is entirely unfamiliar to you) | [
"Many consider Augustus to be Rome's greatest emperor; his policies certainly extended the Empire's life span and initiated the celebrated \"Pax Romana\" or \"Pax Augusta\". The Roman Senate wished subsequent emperors to \"be more fortunate than Augustus and better than Trajan\". Augustus was intelligent, decisive,... |
why does eating human flesh lead to "the shakes"? | Kuru is a real life disease caused by a prion transmitted through consumption of infectious brain matter.
It was first noted in Papua New Guinea in the 1950s and 60s and has largely remained only in that area due to endocannibalistic practices. They eat their dead.
Eating the flesh of a person who wasn't infected with the disease isn't harmful. At least no more harmful than eating most other meats. | [
"In modern humans, necrophagy (eating of dead/decaying flesh) occurs rarely in most societies. This is likely an adaptation to the risk of disease, due to humans having lower levels of protective acids in the digestive tract, compared to species that are dedicated scavengers. Many instances have occurred in history... |
what actually are the trigometric fuctions? | EE student bored at a huge family Thanksgiving meal, I'll give this a shot.
The sine function takes an angle, traditionally labeled 'theta', as its input, and spits out the corresponding ratio between the opposite and hypotenuse sides of a triangle. Specifically, using [this image](_URL_2_) as a reference, you can say that sin(theta) = opp/hyp.
If you were to plot the sine function as theta varies from 0 to 360 degrees (as theta is just an angle), you would get the classic "sine wave" - this is simply a plot of how the ratio between the sides of a triangle varies as you change theta.
[This gif](_URL_4_) should help with the intuition a little bit, here's what's going on: if you watch as the circle (with radius 1) is traced out, really what you are seeing is a triangle with the ratio between sides varying as a function of the angle, the definition of the sine function. [Here](_URL_3_) is what you would see if you took a snapshot of the previous gif. As you let theta increase in the picture, if you reach 90 degrees (pointing straight up) you'll have hyp = 1 and opp = 1, so sin(90) = opp/hyp = 1, as expected. Similar reasoning will show that sine(180) = 0 (since opp = 0), and you can continue to move around the circle to find whatever sine value you are interested in. Understand - **asking for the sine of any number is just like asking "what is the ratio between the opposite and hypotenuse of a triangle with this angle?"**
Following so far? Here's where it gets interesting.
Sine, described above, gives you the ratios between the opposite side and the hypotenuse. If hyp = 1, then sin(theta) = opp/hyp = opp. In other words, it is just the vertical component of the diagonal vector. [Visually](_URL_0_), if we say that the hypotenuse of the triangle represents force (labeled F), taking the sine of the angle will give you the vertical component of the force vector (labeled Fy in the image). Now, since sine is defined as sine(theta) = opp/hyp, we can say: hyp*sine(theta) = opp. In other words, given a vector we can find the vertical component using sine.
But what if we wanted to find the horizontal component of the vector? Well, cosine is defined as cosine(theta) = adj/hyp. It shouldn't be hard to convince yourself, using a similar argument, that the cosine simply spits out the horizontal component of a vector.
EDIT: I messed this up, slight correction in the comments below. ~~Logically it follows that if you take the sine and cosine of the same angle and add them you will always get 1 - sine and cosine can be thought of as the "percentage" that the vertical and horizontal components respectively contribute to the vector of interest, 1 being 100%, which is why sin(90), a vertical line, is 1, while the cosine of the same angle is 0. This is why sin(45) = cos(45) = 1/2, both the vertical and horizontal components contribute equally to the vector pointing at a 45 degree angle.~~
As an aside, [if you plot the cosine and sine of an angle on the same graph](_URL_1_), you'll notice that the sine and cosine functions are related - specifically, cosine is just sine shifted over by 90 degrees, i.e. sin(theta + 90) = cos(theta). Interestingly, if you noted the "slope" at every point of the sine function and plotted it you would get the cosine function. This means, by definition, that the derivative of sine is cosine - I'll leave it at that to keep this in the context of ELI5, learn calculus for more detail.
Finally, we can get into an amazing theorem devised by my main man Fourier - essentially, using the fact that sin (and by extension, cos) are the most fundamental way of mathematically expressing periodic (repetitive) motion, Fourier proved that any periodic motion, no matter how complicated, can be expressed as the sum of simple sin and cosine functions (a Fourier series). This is the heart of modern signals processing used in engineering and technology.
| [
"In the mathematical study of rotational symmetry, the zonal spherical harmonics are special spherical harmonics that are invariant under the rotation through a particular fixed axis. The zonal spherical functions are a broad extension of the notion of zonal spherical harmonics to allow for a more general symmetry ... |
Why doesn't the US-Canada border follow the St. Lawrence River all the way to the Atlantic? | A very brief answer can come from looking at patterns of European colonialism. The Mississippi river, the St. Lawrence, the Columbia, the Fraser, all these are rivers that when they reach the ocean they come out in the middle of a political unit rather than as a boundary. This is largely because while rivers can represent borders, they more commonly represent the center of a drainage system, whose inhabitants move back and forth, and colonial powers tend to compete for control of the mouth of these systems, and to develop settlement around them.
In the case of the St. Lawrence, this meant that France brought settlers to the river, who settled it on both sides up the river, forming a political unit, and while later an international border was created along a portion of the river, it was largely undeveloped land further upstream than these communities that was able to be divided in such a way. This portion of the boundary was determined in 1783 at the treaty of Paris. | [
"Development of the St. Lawrence River which serves as a border between Canada and the United States was in its early stages in 1871 when the Treaty of Washington was signed, which in part demarcated the St. Lawrence River as a boundary and offered Americans greater use of the Canadian side of the river for shippin... |
What type of weapons would have been available to medieval peasants? | Many of them would have access to spears, which would probably constitute the bulk of their weaponry. Also, depending on the time and place, many would also be equipped as archers. Many small villages had competitions for archery on a regular basis, especially in England. The spears, in particular, are easy and super-cheap to make. Swords and specialized weaponry were very expensive to create.
But that being said, the idea of a "peasant levy" as a regular feature of armies is not really accurate. There are notable examples (Hussites, various town militias, etc.), but the bulk would be a kind-of "middle class" or mercenaries. Most feudal societies had requirements for providing arms, armor, equipment, and men based on wealth/land size. (The term "Knight's Fee" is a good example, as it represents the amount of land necessary to support a knight and his retinue.). You don't really want to plop the raw labor force for your agriculture (and source of your income) into a situation where they are likely to all die. The feudal system was definitely propped-up by the creation of a military "caste" that protected it.
This also varies widely based on where and when you're looking for. "Peasants" don't necessarily exist everywhere. To use a different region, the warriors of most Steppe-based armies would be equipped to use Bows, Spears, and/or Lassos, particularly bows. On the counter, many of the militias bordering the Steppes would be focused on utilizing light cavalry, hiring other contingents of Steppe tribes, or trained in ranged weapons. | [
"As far back as medieval times, if not Biblical times, there was pressure from landowners to demand heaped bushels of commodities from their peasants, while at the same time peasants were obliged to purchase commodities from stricken containers. Rules outlawing this practice were circumvented through use of heavy r... |
At what point did European settlers outnumber Native Americans in what would become the modern United States? | This is a huge, and interesting, question. I'm afraid our current data can only go so far in providing an answer. What follows is an analysis of the data, and the pitfalls of trying to definitively answer this question due to everything from notions of identity, evolving racial categories, and lack of solid sources. I will first address the research surrounding Native North American population size at contact, then the issues with calculating the rate of decline until the numbers hit a nadir around 1900. I will then address historical census numbers for the European and African descent populations of the United States. Finally, I will emphasize how all of this is simply an educated guess, based on flawed sources, that reflects a dark history of our nation’s interaction with Native Americans.
First, gallons of ink have been spilled debating Native American population size at the time of contact. There are two main camps, “high counters” and “low counters”. In the early 1900s scholars like Kroeber and Mooney looked at the Native American population size during their time, and assumed little changed in Native American lifeways between contact and 1900. They didn’t factor in mortality from disease, warfare, and famine. Kroeber estimated 900,000 people lived in North America, and 8.4 million lived in the entire New World. That is a population density of less than 1 person for every six miles. Other scholars, like Dobyns, formed a group called “high counters”. The high counters held the New World was richly populated at contact, but catastrophic disease spread ahead of colonists, decimating the population, and rendering any colonial-period estimates of population size grossly inaccurate. Dobyns estimated over 112 million people lived in the New World at the time of contact. For reference, only 11 countries today boast a population larger than 112 million.
Today the popular perception has inherited the legacy of the high counters, and their catastrophic, apocalyptic population decline due to infectious disease after contact. In academic circles we are stepping back from the assumption of epidemic disease decimation without concrete evidence of that disease mortality. For example, ten to twenty years ago we might look at a Mississippian site abandoned around 1525 and assume disease carried off all, or at least most, of the inhabitants. However, we now know for many people in North America geographic mobility was a regular means of dealing with resource scarcity, or territorial encroachment, or changes in the political structure. The interpretations of the evidence have changed, and with that change we must modify how we reconstruct the past. All that said, current best evidence suggest the Native North American population size at contact was between 2 and 7 million people.
As you can see, there are a host of issues and assumptions that go into calculating the Native North American population in 1492, and those issues are only magnified in the years following contact. Native American population size, and subsequent decline or rebound, varied based on geographic location and time. Centuries of warfare, population displacement, epidemic disease mortality, famine, territory restriction, and identity erasure wreaked havoc on Native North Americas. Calculating raw numbers is next to impossible. Native Americans were not included in the U.S. Census until 1860. An attempt at a total count of Native Americans throughout the U.S. was not realized until 1890. Compiling first hand estimates given by those traveling into Native American lands can only tell us so much from their limited perspective. Scholars generally agree the Native American populations hit their nadir (lowest point) by 1900 when the U.S. Census total for American Indian, Eskimo and Aleut was 237,196 (roughly 0.3% of the U.S. population). Since the population decline debate is so contentious, I’m just going to focus on when the “White” population of the United States passed the upper bound of the best estimates of Native American population size at contact.
Continued below... | [
"Henry F. Dobyns estimates that immediately before European colonization of the Americas there were between 90 and 112 million people in the Americas; a larger population than Europe at the same time. \n",
"With the advancement of European colonization in the territories of the contemporary United States, the Nat... |
why does the body consume carbohydrates first and then fats when exercising? | The actual answer is a bit more complicated than that. What cells actually use for fuel is ATP, which is an energetic protein that we make using carbohydrates, fats, and other things as a fuel source.
ATP is mostly produced by mitochondria, organelles inside cells, and muscle cells have a lot of mitochondria.
At any given time, we have a little bit of liberated sugar, glucose mostly, which is floating around in the blood, being taken up by cells that need to produce more ATP, and being used by them to make ATP. When we start to exercise or burn a lot of calories, the amount of free glucose we have in the blood goes down, so we start liberating it by making more out of molecules we have stored.
The big ways we store energy are as glycogen, a long-chain sugar in the liver, and fat. It is pretty easy to separate glucose from glycogen, so that is the first form of reserve energy we go to. It is a more time-consuming process to make glucose from fats, and there are more bad by products produced. So we don't start burning fats until our bodies know we are in it for the long haul. | [
"Carbohydrates are the main source of energy in organisms for metabolism. They are an important source of fuel in exercise. A study conducted by the Institute of Food, Nutrition, and Human Health at Massey University investigated the effect of consuming a carbohydrate and electrolyte solution on muscle glycogen use... |
What is actually happening when I hear my timber framed house 'crack'? | It would be better described as creaking rather than cracking. When a door creaks, the hinges aren't cracking, there's just resistance that builds up until friction can no longer stop the hinge from moving. The same applies to the beams in your house as some parts of the wood heat & expand faster than others. | [
"An investigation of the scene afterwards found that seventeen joints had given way causing a hole approximately long to open up in the stand. Several witnesses in the crowd reported hearing loud cracking noises prior to the collapse and one witness, who worked as a joiner, claimed to have seen the wooden boards sp... |
why can't a country in a trade surplus be sustained in that position indefinitely? | It can.
Imagine you have a job at a convenience store where they give you a 50% discount on baseball cards. You don’t care for them much, but your friend does. He regularly buys them from you for 90% of list. You never buy anything from him.
Your friend has a trade deficit with you. The trade, though, is beneficial for both of you and you’ll keep doing it as long as it works out for both of you. And you’re not living outside your means to do it.
Your teacher may have been talking about a budget deficit, which is a whole different thing. That is living outside your means.
*edit: I had the trade deficit backwards. Macro at 7am never safe. | [
"If a country's resources were not fully utilized, production and consumption could be increased at the national level without participating in international trade. The whole raison d'être of international trade would disappear, as would the possible gains. In this case, a State could even earn more by refraining f... |
This Week's Theme: Immigrants and Emigrants | **Current:** Immigrants and Emigrants
**On Deck:** Trauma
**In the Hole:** The Balkans
Remember to ask theme-related questions in [a new thread!](_URL_1_)! If your submission doesn't get automatically flaired, [send us a modmail](_URL_0_) with a link! | [
"\"The Emigrants\", the works about the Swedish emigration to North America, written by Vilhelm Moberg that have spread around the world have put a focus on many places in the municipality mentioned in the novels. Moberg himself was born on a farm just north-west of the town Emmaboda in 1898, where a monument stone... |
- why is citizen kane considered to be the pinnacle of movie making? | It's less about being the pinnacle of movie-making and more about being the _start_ of modern movie-making.
In _Citizen Kane_, director Orson Welles revolutionized how films were shot. There are a number of cinematic techniques that were introduced in _Citizen Kane_ including low angle shots, multiple dissolves, deep focus, non-linear storytelling (in particular supported by the film editing), people talking over one another (most films were shot then as back-and-forth dialogue), full sets with four walls and a ceiling (most films then were shot on sets like stage plays -- 3 walls, no ceiling), incorporation of fake documentary/news reels (which Welles had pioneered on radio with _War of the Worlds_), expressionistic lighting, and more.
All of these things are so commonplace today that you'll see them in many 30-second commercials, never mind feature films. But in 1941 they were all almost entirely new innovations that people had never seen until _Citizen Kane_.
Watching _Citizen Kane_ today, you'd think "What's the big deal?" But the *reason* you think "What's the big deal" is because of all the techniques that _Citizen Kane_ introduced to cinema.
Possible recent analogy: think about how the special effects of something like _Jurassic Park_ or _The Matrix_ in the 90's or maybe _Avatar_ in 2009 changed the way that people thought about how films could be made. _Citizen Kane_ had _ten times_ the impact that those films had in people's thinking about how films could be made. | [
"In the decades since, its critical status as the greatest film ever made has grown, with numerous essays and books on it including Peter Cowie's \"The Cinema of Orson Welles\", Ronald Gottesman's \"Focus on Citizen Kane\", a collection of significant reviews and background pieces, and most notably Kael's essay, \"... |
what is the difference between federal debt and u.s. treasury securities? | The debt is issued through the use of US Treasury securities. The government sells a bond, and the money collected from the bond buyer increases the debt until the bond is paid back. | [
"Treasury securities are backed by the full faith and credit of the United States, meaning that the government has promised to raise money from any available source to repay them. Although the United States is a sovereign power and may default on its debt, its strong record of repayment has given Treasury securitie... |
why does semen lose its white color after 5 min? | Ok, so: semen contains very little actual spermatozoa and a lot of other components, one of which are alkaloids produced by prostate to - basically - neutralize the acidity in a vagina, so that the spermatozoa survive long enough to reach the egg.
The alkaline stuff oxidises when it contacts the oxygen in air, which makes it change colour.
^(source: high school biology, I guess?) | [
"Semen that has a deep yellow color or is greenish in appearance may be due to medication. Brown semen is mainly a result of infection and inflammation of the prostate gland, urethra, epididymis and seminal vesicles. Other causes of unusual semen color include sexually transmitted infections such as gonorrhea and c... |
sinuses | Sinuses are hollow cavities in the skull to lighten the bone structure. They are lined with mucous tissue, and can be subjected to allergens, causing the mucous to swell and produce mucus. This can plug up the sinus cavities and cause pressure and pain. Why your throat swells up and goes numb really has nothing to do with your sinuses. It probably has more to do with histamine release that caused the sneeze in the first place. Here is a good pic of sinuses. _URL_0_
As far as not tasting, it's probably because her sense of smell is diminished from sinusitis.
She needs to see a doctor. I suffer from sinusitis, and it's horrible. There have been cases where the sinusitis has been caused by nasal polyps, which can be removed fairly easily if they are small. Most sinus problems are allergic or viral/bacterial. | [
"In human anatomy, the carotid sinus is a dilated area at the base of the internal carotid artery just superior to the bifurcation of the internal carotid and external carotid at the level of the superior border of thyroid cartilage. The carotid sinus extends from the bifurcation to the \"true\" internal carotid ar... |
if you start off completely awake and energized but then start dozing off during a boring class or a study session, what exactly is happening physiologically to cause this ? | Your brain notices that there's nothing of interest going on at the moment, and tries to shut down to conserve energy. Your studying might be important to you in a higher-function way, but at a core animal level, it's not food, sex, stimulation, or entertainment, and so you're just wasting energy and calories (and therefore dangerously wandering towards starvation and death) by being alert and awake. | [
"Automatic behavior can also be exhibited whilst in the REM state—subjects can hold conversations, sit up and even open their eyes. Those acts are considered sub-conscious as most of the time the events cannot be recalled by the subject. It is most common when the subject has had under 10 hours sleep within a 36-ho... |
if supermarkets have a defined science/art as to where products are located, why are they all different? | Numerous factors-
1 Store size. Different stores are different sizes, and shapes depending on the area they are situated and the availble space/ planned market.. What works for one floor plan doesn't neccesarily work for another.
2 customers. Customers in different areas like different things, so different branches carry different products, and or different stock levels. This means certain types of product need more space in some stores then others.
3 There's more then one possible arrangement that works well.
4 They do tend to have LOTS of things in common. Walk into any supermarket. Fresh Fruit and Veg is almost always the first thing you come to. Dairy products are always kept together. Dental and medical supplies are in the same isle, sweets biscuits and crisps are next to one another. And so on. | [
"Supermarkets are designed to \"give each product section a sense of individual difference and this is evident in the design of what is called the anchor departments; fresh produce, dairy, delicatessen, meat and the bakery\". Each section has different floor coverings, style, lighting and sometimes even individual ... |
why do people with loads of money still attempt to earn more money? if you have millions in the bank isn't that more than enough? | Generally I would say that people who are millionaires tend to have a high performance drive. They desire to always perform better. This is what made them wealthy in the first place, and this is what makes them desire ever more wealth. You can always do better.
Furthermore, once you reach the level of being a millionaire, you'll move to a new level of wealth. You'll have all these people around you who are wealthier than you are and can do and buy things you can't. So compared to them, what used to be enough all of a sudden isn't enough anymore.
That is my take on it anyway. | [
"Author Ric Edelman writes: \"You don't make any money in bank accounts (in real economic terms), simply because you're not supposed to.\" On the other hand, he says, bank accounts and CDs are fine for holding cash for a short amount of time.\n",
"It is not uncommon to come across individuals from whose company a... |
What is the longest "unbroken" chain of royal or dynastic succession in known history? | Japan has the oldest continuous, hereditary monarchy in the world -- and would, I believe, even qualify as oldest if we included non-hereditary or interrupted-hereditary successions. The Japanese royal family is still in the Yamato Dynasty, which took over the Japanese throne (according to legend) in about 660 BC under Emperor Jimmu. This means there has been a continuous line of descendants (traditionally, Japanese emperors must be male, but there have been several empresses in Japanese history -- though these generally succeeded in extraordinary circumstances) for nearly 2700 years.
However, evidence for the first two dozen or so emperors in the Yamato Dynasty is scanty by modern, empirical history standards, and the first emperors are semi-legendary in status. Therefore, the Japanese royal line is often dated back to the time when we have solid evidence in line with modern standards of historicity -- which takes us back to about 500 AD with the birth of [Emperor Kinmei](_URL_0_).
That said, even discounting that first 900+ years of semi-dubious imperial lineage, the Japanese monarchy would still be about 1500 years old, the longest continuous dynasty in the world by a significant margin. To give a historical context, the last emperor of the Western Roman Empire, Romulus Agustulus, was (probably) still alive about the time Emperor Kinmei was born, and Kinmei's dynasty is still on the throne today.
Sources:
* Packard, Jerrold: *Sons of Heaven: A Portrait of the Japanese Monarchy (1987)*
* Hoye, Timothy *Japanese Politics: Fixed and Floating Worlds* (1999) | [
"This list of current longest ruling non-royal national leaders is a list of the current living longest ruling heads of nation-states or national governments, who are not royalty, and have served ten years or longer, sorted by length of tenure.\n",
"Sobhuza's official incumbency of 82 years and 254 days is the lo... |
Why is it that humans can be sustained on some leafy plants (spinach, lettuce, kale, etc) but not others (ferns, tree & and flower leaves, etc)? | It depends on what that source has to offer. Most leafy plants commonly eaten are considered "greens" like Kale, Spinach, Arugula, etc., and are eaten for the vitamin and mineral content. "Greens" are an essentially non-caloric or low calorie, nutrient dense source of minerals that would be difficult to consume through another source. Minerals such as Magnesium, and Potassium are key to your health and leafy "greens" offer massive quantities of these nutrients.
*Note: Not all greens are actually green.*
That's not to say you couldn't sustain yourself on things like fern. There are numerous amounts of wild flowered plants you can boil and pop in your mouth as a snack, but it would require a larger amount to be consumed since they aren't necessarily packed with minerals and/or nutrients. | [
"The plants are relatively easy to grow and care for, having few insects that feed on them. Mites, though, are known to feed on the plants. The plants are also susceptible to leaf spotting, root rot and root strangulation. However the former two can be prevented by avoiding a damp soil and the latter by frequent we... |
how to barcode scanners instantly detect what an item is, despite the barcode being at any angle and often on a crinkled surface, completeley changing the look of the code from the scanner's perspective? | The lasers that read the barcode hit it from many angles and scan it very quickly. Also barcodes have something like a checksum, where it's easy to recognize if the data that was read is garbage and needs to be read again. That's why when using hand scanners, like at the grocery store, sometimes it scans a valid item very quickly, and somtimes it takes a while.
The built-in scanners in the checkout lanes have lasers that shot from the sides and from the bottom. | [
"This application supports many different types of barcodes, including those used to identify products in commerce. The Barcode Scanner can automatically search the Web to identify a product with a barcode and use, for example, price-comparison information between vendors.\n",
"By using the barcode center marker,... |
Is there a historical reason why the US military says klick instead of kilometre? | It's not official, it is military slang, and is used purely because it is easier to say. | [
"BULLET::::- That when American servicemen heard the term during the Korean War, they heard the word as 'gook\" instead of k(g)uk which means \"national\" (maybe, thus, interpreted as nationalist) \"goo-goo\" (also \"gugu\"), a term used by the U.S. military to describe Filipinos.\n",
"The slang term \"SWAG\" is ... |
why do most websites have character limits for passwords while at the same time they force you to have an upper/lowercase letter, and a number to make your password more secure. wouldn't removing the character limit and allowing much longer passwords make them more secure than 16 characters? | Convention.
There is no technical strength to doing so. Users who will use insecure passwords without the restrictions will use insecure passwords with the restrictions, and cracking these cases isn't all that much more demanding. Meanwhile, increasing password length does substantially increase security. It would be far better practice to have, say, 10 characters minimum and no maximum than is currently common. | [
"Many policies require a minimum password length. Eight characters is typical but may not be appropriate. Longer passwords are generally more secure, but some systems impose a maximum length for compatibility with legacy systems.\n",
"The full strength associated with using the entire ASCII character set (numeral... |
Whats the difference between Centrifugal and Centripetal force? | Its often taught in PHY 101 courses that the centripetal force is "real" while the centrifugal force isn't. In a purely inertial sense, this is true, however it oversimplifies how we often times approach a lot of real problems in physics. A lot of the confusion comes from the fact that they both describe the same phenomenon in a rotating body.
The **centripetal force** is the force required to keep an object moving on a circular path while traveling at some tangential velocity. It points directly in towards the center of rotation.
The **centrifugal force** only exists in rotating reference frames, though it's important to recognize that this doesn't mean it's incorrect to talk about! It is mathematically valid, you just need to be careful about when discussing/using it. It is the experienced "reaction force" when an object is traveling in a circular path. It points "away" from the center of rotation.
So if you have a ball on a string and you start spinning it around in a circle faster and faster, eventually the string will break. From an inertial reference frame, this is because the string can only apply a limited amount of force before it breaks (this is its tensile strength). And when the ball is moving fast enough, in order to keep it moving in a circular path at its speed, requires a greater centripetal force than the string can supply.
From the strings perspective though, if you were rotating with it, you'd watch the string continue to be stretched more and more as if being pulled on by some outward pointing force. This is what we call the centrifugal force. While it isn't "real", it is useful when dealing with rotating reference frames.
Note:
**Inertial Reference Frame:** a non rotating and non-accelerating reference frame where Newton's laws hold. That is, objects at rest stay at rest and objects in motion stay in motion. | [
"In Newtonian mechanics, the centrifugal force is an inertial force (also called a \"fictitious\" or \"pseudo\" force) that appears to act on all objects when viewed in a rotating frame of reference. It is directed away from an axis passing through the coordinate system's origin and parallel to the axis of rotation... |
what's actually happening when someone overeats on a regular basis and their stomach "expands"? what about in reverse when their stomach gets "smaller"? | It's not just a figure of speech. Your stomach can physically expand/stretch. [Competitive eaters expand their stomachs for competition using water](_URL_0_). It really is like a balloon in a way. The size of the actual organ doesn't change, but it's elasticity and response to food can.
The opposite is not true however. You cannot shrink you stomach. It is an organ and does not change size. What is happening when your stomach "shrinks" from not eating is you appetite resets. You stomach has nerves around the outside that indicate when your stomach is "full". Those may begin signaling earlier if you have not eaten in a while. | [
"Gastroparesis (gastro- from Ancient Greek γαστήρ - gaster, \"stomach\"; and -paresis, πάρεσις - \"partial paralysis\"), also called delayed gastric emptying, is a medical disorder consisting of weak muscular contractions (peristalsis) of the stomach, resulting in food and liquid remaining in the stomach for a prol... |
rental car insurance. | I called my insurance company to make sure that my policy is the same whether I'm driving my car or a rental. It does except for what they call "loss of use." The way I understand it, if you crash the rental, insurance will cover damages to it, but the rental company can claim losses because it would have been making them money if it had not been crashed.
I didn't ask the rental company if loss of use was covered with their insurance, but I'm assuming it is.
So, for me, the answer is not really, unless you're planning to really fuck up the rental. YMMV. | [
"Most rental car companies offer insurance to cover damage to the rental vehicle. These policies may be unnecessary for many customers as credit card companies, such as Visa and MasterCard, now provide supplemental collision damage coverage to rental cars if the rental transaction is processed using one of their ca... |
If Alpha Centauri had a solar system like ours, how big would the outer planet's orbit appear in the sky if visible with the naked eye? | If the planetary system was completely face on and if we assume that it's an Earth like planet orbiting at 1 AU, then it would appear approximately 4x10^-4 degrees wide. That's about 0.012 arc minutes, and a quick wiki check says that the best a human eye could do is around 1 arc minute. So no way you'll see it.
Note that Alpha Cen is probably not a good target since it's a binary (well, technically a triple) star system. | [
"Viewed from near the Alpha Centauri system, the sky would appear much as it does for an observer on Earth, except that Centaurus would be missing its brightest star. The Sun would be a yellow star of an apparent magnitude of +0.5 in eastern Cassiopeia, at the antipodal point of Alpha Centauri's current right ascen... |
Can you name some important historical travelogues? | Forgive me, I am not certain what you mean by 'undercover regions'. Lady Mary Wortley Montagu's travel writings on Turkey and other countries are used as primary sources. Her relish in appealing to her audiences means her writing isn't always reliable as verbatim records of events, but is insightful for us for a range of reasons. Including for understanding then prevailing views of some English people of the Occident and Orient. | [
"BULLET::::- Travel Writing: The text of most of the best known historical British travel writers, including James Boswell, William Camden, William Cobbett, Daniel Defoe, Celia Fiennes, Charles Wesley and Arthur Young. The earliest source included in the GB Historical GIS is a survey of Wales written by Giraldus Ca... |
During WW2, were there any significant acts of sabotage executed by the Axis powers on U.S. soil? | The case of Ex Parte Quirin is of note here, if only to show how inept German sabotage was for the time. A handful of covert German operatives deposited by submarine on the American eastern coast landed in uniform, to comply with the laws of war, buried their uniform, to get around the laws of war, and then started to get busy- only to all be captured within a month or so of their arrival. The issue of whether or not they should be afforded Geneva Conventions is the one the Court takes up in Quirin. Worth your time to read.
The Japanese also launched a series of incendiary hot-air balloons bound for America, but as far as I know, they caused no significant damage to property or persons in the continental United States. | [
"During World War II PRR carried troops and matériel for the Allied war effort, and the Curve was under armed guard. The military intelligence arm of Nazi Germany, the \"Abwehr\", plotted to sabotage important industrial assets in the United States in a project code-named Operation Pastorius. In June 1942 four men ... |
[mod post] coming soon...on rules and mods. | Can we make sure the rules do more to encourage searching for answers first? Especially around big news events, the old classics of '3d printing' and 'schrodingers cat' come up constantly too. A giant red bar that flashes up when you mouse over submit like on askscience or TIL might help. | [
"The purpose of Mod DB is to list the mods, files, tutorials and information of any games that are capable of being modded with user-made content. Community involvement is strongly encouraged, and any game mod with a website is allowed to post a screenshot gallery, news, and requests for help. Scott's intentions, f... |
How accurate are the assumptions made by the blog medievalpoc concerning nonwhite peoples in medieval Europe? | So, for the record there was [this conversation last week](_URL_0_) which examines some underlying assumptions in using 'race' as any sort of measuring stick of human descriptions before our epoch.
'Non-white', the same as 'black', or 'asian', or any other modern race definition are just that, modern which is what /u/telkanuru is referring to as a 'sociological construct' in the linked answer. So, we are faced with two problems when we look backwards into Medieval Europe.
\1. The first is the problem of whether the verbal or visual language we receive from the past actually conforms to our indicators of race. The first hurdle is translation, and the second is idiomatic expression. Did a reference to someone being 'black' in Latin actually mean a 'black' person, or did it mean someone with black hair in a culture where black hair was unusual? Or even further, did reference to 'black' actually mean some local idiom which referred to an aspect of character or of origin lost to us now?
This first point is important because, from examples within my field - the medieval period - we are not going to find chroniclers referring to 'some black guy from nigeria' or some such thing. We have references to Moors, or Moslems, but they might look 'Latino' or 'Middle Eastern' to modern 'scales of race'. Is that a separate race? We might have a reference to someone from Egypt. Or Africa. How are we to establish the race of the referent under these terms?
When it comes to visual depictions like we frequently see in MedievalPOC blog, we don't know if the manuscript, painting or fresco coloration is always actually a reflection of a racial difference or if it holds some other meaning. This is not to discredit the blog's intent or assertions entirely, but merely to problematize the assumptions to the point where we return to the same question.
What we can say is that pre-modern western sources did not care to establish race according to what we think is now important. Consider this inversion for a moment: in place of whites and blacks, were are more likely to have heard prior to 1000 a discussion of the natures of the 'race' of Angles, Saxons, Franks, Germans. How are we to reconcile our modern notions of race with these terms?
\2. The second problem is depth of evidence. If we take some written or visual depictions as actual reflections of skin colour, and therefore of modern race (and I hope you already see the massive problems just getting us to these assumptions) are these 'frequent enough' to make broader assumptions about 'people of colour' in the medieval world? Again, we just don't know because again pre-modern sources didn't use race the way we use race. In medieval society it was apparently far more important to establish whether someone was Christian, or not Christian: that was worth noting.
All of the above can pretty much stop us from answering a well-intentioned question about modern notions of representation of race so important in many modern discourses. So, that said, I'd like to answer your question on its own terms, whether those we classify as 'non-white' (according to, say, an American census form) were visible in daily life in Western Europe. Realzing of course the depending who you ask today non white may or may not include 'latinos' (Spain) or 'arabs' (again Spain, and many other parts of Mediterranean Europe).
Here's a lot of ifs and mights for you:
* Vikings were exceptionally well travelled 800 -1000 and they may have encountered 'black' people in lower Spain, or southern Italy, or Constantinople, or in the Holy Lands. It is possible that they might have slave-traded 'blacks' or 'middle easterns' and some may have returned to northern ports.
* The Moors of Spain were established through the Moslem invasions of the Iberian peninsula.Those Moslems had come across from north western Africa and so may have included 'blacks' and certainly 'middle easterns'. Those same moors travelled up into southern France and established themselves in colonies and cities from Toulouse to Narbonne to Provence. They established forts and castles in Provence. Beyond the incursions and wars, Moslems travelled up and down the Rhone river trading slaves to 1100. Moslems also frequented ports of Southern France like Montpellier and Nice.
* Of course the various crusades brought Western Europeans in contact with peoples of the middle east which definitely included 'arabs' but might also have included 'blacks' and 'asians'.
* There is some evidence of Irish contact with Mediterranean peoples in the early middle ages - some of those people might have been 'non-white'.
* And of course throughout the medieval period, from late antiquity through to renaissance, we have the travelling merchant; he might have been from northern Europe, or he might have been from southern Europe; he might have encountered 'non-whites' or he might have been 'non-white' himself.
So we can gather from above that some inhabitants of some towns and some cities in medieval Europe all the way up to parts of Scandanavia encountered 'non-white' peoples, whether they be described by modern terms as Arabic, Middle Eastern, Black.
How many and how far afield into the very rural landscape of medieval Europe? Who knows. And anyone who makes generalist claims for or against is not arguing about the past but arguing politics of today. It holds something of a lesson if we care to look at it: race is constructed, not eternal.
Whatever we aren't sure of, we can be certain of one thing: there was no such thing as 'white society' in the European medieval period.
note: this was moved from response to top level in hopes of people reading it and discussing. | [
"Digital Medievalist sees it as its mission to provide a framework to enable members of its community to share information. These activities include an electronic mailing list, the participation in and organisation of conference sessions or other events, and a website containing an open-access academic journal of r... |
When did Americans start using French words and phrases, and why are they so prevalent? | Although English is a Germanic language, approximately 30% of English vocabulary comes from French in one form or another. This is largely caused by an event called the Norman Conquest, in which a group of people called Normans, who inhabited Northern France and had a degree of Scandinavian ancestry, invaded and conquered England. The Old English-speaking aristocracy was mostly replaced by Norman French-speaking aristocracy, and for at least a hundred years, the nobility of England were primarily Norman French speakers. As a result, many words in English, particularly ones related to politics, warfare, and social class come from French. Many of these Norman French words are different from their modern French words, such as the word castle, from Norman French castel, in comparison to Modern French Château (which had evolved from Chasteau as indicated by the circumflex accent). Eventually, likely around the early or mid 13th century, the Norman/Angevin aristocracy of England lost most of their titles within the Kingdom of France and began to transition to English, which by this point was now full of French words. The higher nobility and Kings of England continued to speak French as their first language until sometime in the 14th or 15th century.
French words continued to enter the English language after England and France became more distinctly separate entities, as France and England were still geographic neighbors (there are quite a few Dutch and German words of French origin as well), and because for a long time French was the dominant language of European courts and was therefore a prestige language that many nobles of various countries learned. Frederick the Great of Prussia, for example, spoke French natively and may have preferred it to German, and the multi-ethnic and multi-lingual Austrian army often used French as a common language. Most of the English words and expressions that remain distinctly and obviously "French" come from these more recent vocabulary exchanges. | [
"As American soldiers and officials traveled through the area for the first time following the War of 1812, they initially used the French spelling. But when large numbers of lead miners streamed into the country south of the river in the 1820s, the U.S. government began to refer to it differently in debates and le... |
Could we use magnetism as opposed to rocketry to launch objects/people/spaceships into orbit? | People talk about doing something like this:
The mass driver, which is similar to some designs for high-speed trains.
_URL_0_
In most cases it's not practical to launch from Earth's surface to orbit with one of these, since you have to launch at high speed through the atmosphere, and your capsule would be burning up when it left the launch track.
The exception is building the track so that your capsule launches at high altitudes - on high mountains or supported on some sort of very high artificial support. | [
"The science of electromagnetic propulsion does not have origins with any one individual and has application in many different fields. The thought of using magnets for propulsion continues to this day and has been dreamed of since at least 1897 when John Munro published his fictional story \"A Trip to Venus\". Curr... |
why are there so many contradictory ideas about what humans should be eating, but other animals are very straightforward in knowing what to eat? | We have the technology to make whatever we want and the resources to get whatever we want. We have a lot more choices than an animal does. It also helps that we're omnivores and able to make any type of food digestible and tasty, while many other animals are stuck being unable to digest one thing or the other.
Animals don't have as many choices, so they stick with what they know and have access to. An animal won't be able to get its hands on much refined sugar or MSG, but if it did, it would eat it until sick. | [
"Ultimately, \"Eating Animals\" discusses the ethics of food. It suggests that our food choices directly reflect the ethical values we stand for. When people eat meat, Foer claims, they are implying that satisfying their desire for meat is more important than letting animals live well, or even live at all. This can... |
In the 1920s, what did people feel nostalgia towards? | This is not to prevent anyone from writing you a full, new answer, but you may be interested in these two answers of mine:
[Why are people today fascinated with the Victorian era?](_URL_0_)
[Dang kids! Or: Why does each generation have such an exaggerated view of fashion in previous ones?](_URL_1_) | [
"In the eighteenth century, scientists were looking for a locus of nostalgia, a nostalgic bone. By the 1850s nostalgia was losing its status as a particular disease and coming to be seen rather as a symptom or stage of a pathological process. It was considered as a form of melancholia and a predisposing condition a... |
The USA had a large percentage of German immigrants in the early 20th century. What was life like for them during WWI and WWII? Did many serve the Allies or did any go back to the “Fatherland”? Also why did the US sell to the British and not the Germans before they entered both wars? | One of the first things you need to think about is why the Germans came over to the US. The vast majority of immigrants came after the failed Democratic revolutions in the 1890s, so they wanted to live in Republican state. That being said while these Germans hated the Kaiser they didn't want war between the US and Germany, simply due to connections back home. This produced huge strains which would impact how they were treated and how these Germans would act in WWII. Anti-German sentiment was so bad that 16 US states banned speaking German in public some states even required that people change their German names to American ones (Smicht to Smith), thousands of beer halls in the US were shutdown or even burned down, Germans were banned from having certain jobs (strategic/Gov't), internment camps were also set up, there were numerous cases of Germans being killed to seriously maimed due to 'Not being patriotic'. For example a man was tarred and feathered for not buying War Bonds, another man was lynched for 'not being American/Patriotic', and a pregnant woman was reportedly nearly beaten to death for speaking German with a local priest ( Although I have read this mentioned in numerous books I haven't hit any primary sources on it). President Woodrow Wilson even called German-Americans 'Alien citizens'. This caused two things 1) Need/Desire for German Americans to prove their loyalty, 2) complete erasure of German Culture. Point one can best be seen in the case of Henry Gunther a German-American who was killed 15 seconds before the Armistice charging a German machine gun, his death was so controversial that it caused a investigation as to why nobody stopped him and why he did it. As to point two close to fifth of the US population (60 Million people) have German ancestry but despite this less than 5 million have German names and less than two million can speak German. So by the time that WWII came along most German-Americans were so disenfranchised with their culture that they no longer saw them selves as Germans but where in stead were Americans. | [
"Before 1900, the main factors in German-American relations were very large movements of immigrants from Germany to American states (especially Pennsylvania, the Midwestern United States, and central Texas) throughout the 18th and 19th centuries.\n",
"But immigrants from Germany, as well as German Americans from ... |
Does brushing your tongue harm your taste buds? | Dentist here.
To answer your question about tongue brushing and potential damage to our taste receptors. Yes and No.
Let's start with how it would be a Yes, and work in to the final answer of No:
If you are using a hard bristled toothbrush, highly corrosive toothpaste (usually whitening toothpaste or something with a thick paste of baking powder mixture), then Yes, you can erode the taste buds on your tongue away.
But is this a permanent change to your tongue?
No. And to explain this, I'm going to explain the make-up of our tongue's dorsal surface (the part that contains our "taste buds").
Our tongue is a muscular instrument which is used to not only taste food, but also to recognize poisons/toxins (partially through taste), to determine the quality of food by texture, and to help you not only hold on to your food during mastication, but to also chew and swallow your food by acting as a muscular plunge.
It contains specialized structures called "papillae" which are outcroppings of the epithelium making up the tongue and are often confused with just "taste buds." There are several type of papillae, and each has their own function.
The most numerous type of papilla is the filiform papilla. It is shaped like a little finger that comes off the surface of your tongue and actually does not really involve itself with taste sensation. They are the the part of your tongue that allows you to hold on to food and determine texture. They are also what make your tongue feel rough when it is dry. If they grow too long or their growth is altered by certain anti-biotics, peroxide-based chemicals, or unusual chemical reactions, then they act negatively to hold on to bacteria or fungus to give you a minor case of something called "hairy tongue." I can explain that more if you like, but it's a bit outside the realm of your question. Overall, if you brush too hard, you're more likely to scrape some of these guys away, so your taste won't really be affected directly. What will be affected is how well your tongue can hold on to food and water (which is absolutely necessary to "taste") so your taste will be indirectly involved. As a neat experiment, try completely drying your tongue off with a dry towel and then put some sugar or salt on it. If you dried it off thoroughly, you won't be able to taste either!
The taste buds actually involved in taste are the fungiform papillae. They are little, mushroom-shaped bumps (as their name suggests) on your tongue interspersed throughout. Their histologic structure actually shows that they're like little caverns with centralized "bulbs" that are connected to the cranial nerves in charge of distributing taste reception. These are very tough to brush away or damage with toothpaste or a toothbrush because of how they are formed and shaped. So brushing them will not affect taste. (This is how we overall come to the answer of "No").
The other types of taste buds are a bit more boring and are located on the sides and back of the tongue. Brushing them would be very hard to do and even if you did, nothing would happen. If you're interested in learning about them further, feel free to read about the Circumvallate Papillae and the Foliate Papillae. They are also involved with taste, but act mostly as a defensive feature where something very bitter or toxic tasting will be ejected just prior to being swallowed. I'm simplifying a bit, but it's close enough to reality to get the point :)
Now, let's say that you did somehow manage to rub off the top layer of your tongue and damage the papillae somewhat. Well, in a little over a week, that'll clear right up as their average turnover is 10-14 days :)
So, now you can see how the answer is both a Yes and No, depending on how you want to perceive it.
But because I really doubt you're going to grind away the top layer of your tongue, rest easy, my friend, and continue to brush your tongue, your teeth, and even the roof of your mouth! Keep your mouth clean and take care of it, because we only get one!
Also, mandatory dentist reminder: Floss!
EDIT: Thanks for the Gold! That was unexpected! :D | [
"Tongue cleaning can cause discomfort. Improper use of a tongue cleaner may induce the gag reflex and/or vomiting. Overuse of a tongue cleaner may also cause damage to the taste buds. Some people have inappropriately used the tongue cleaner to scrape or brush the lingual tonsils (tongue tonsils).\n",
"The tongue ... |
if redbull lost a lawsuit over their "gives you wings" slogan, how do the current commercials still include the slogan without a small disclaimer included? | Actually, that law suit (for $13.5 million) was not because of the tagline "give you wings" (which is clearly understood as humor).
The law suit was over the fact that Red Bull oversold the drink's ability to improve concentration and energy, specifically, it did not provide any scientific evidence to support their claim that the drink is "able to boost energy better than a cup of regular coffee"--considering that a 8 oz of Red Bull contains less caffeine than 8 oz of coffee, their claim is blatantly false. | [
"In 1999, animated advertisements were part of the early GEICO Direct ads as well as the \"Dumb Things\" campaign. The 15-second long commercials, animated by Bill Plympton, featured a curious little man walking up to an object and eventually getting hurt due to his curiosity about the object. One of the commercial... |
What gods were foreign and then adopted by the Greeks and Romans through trade/war/etc? | A few of the most famous examples of Roman religious syncretism are the cults of Isis, Mithras, and Sulis.
Isis was an Egyptian goddess of magic and mother of Horus, God of the Pharaoh. She was an incredibly important figure in the Egyptian pantheon so it's no small wonder that her cult thrived under the rule of the Ptolemies after Egypt was conquered by Alexander of Macedon in the 4th century BCE. When Cleopatra died and Octavian claimed Roman conquest over Egypt, slowly the cult of Isis began to take hold. Her cult would later become wildly popular amongst the Romans in Egypt, who would spread it far and wide. A large temple to Isis was even found as far north as Londinium, thousands of miles from her original home on the banks of the Nile.
Speaking of Roman Britain, one of the Romans most effective methods of conquest was extremely passive, that is to say they imposed no religious doctrine on their recently conquered peoples. Rather, they attempted to find common grounds between the native deities and their own. A god called Sulis had a large following within the north of Roman Britain, near what is currently the city of Bath. Sulis shared many properties with the Roman goddess of war and wisdom Minerva, so the Romans stuck them together and called the deity Sulis Minerva. In this way not only did the Romans assuage any fears of Roman imposition of religious practice, but they also helped introduce those practices passively. Scholars have argued this was almost a more effective tactic than military might for ensuring conquered peoples stayed Roman (although the issue is far more complicated than that).
Speaking of the military, the cult of Mithras was hugely popular with them, and with the military being found in all corners of the Empire, it's no surprise that cults to Mithras are also found everywhere in the Empire. Mithras was originally a Zoroastrian deity from the near East who was implanted throughout the empire by those same soldiers, and the cult spread from there. Mithraism is a highly structured religion, with seven levels of religious initiation. This highly rigid rank structure mirrored the rank structure the soldiers were already familiar with in the Army and provided yet more incentive for promotion (one has to wonder if an experienced Mithraic infantryman had the potential to exercise power over his newly initiated commanding officer). Mithras was also a warrior and sun deity, the symbolism and significance of which also mirrored the desires and lifestyles of the Roman military. | [
"In the subsequent Greco-Roman period, there is evidence that the worship of non-indigenous deities was brought to the region by merchants and visitors. These included Bel, a god popular in the Syrian city of Palmyra, the Mesopotamian deities Nabu and Shamash, the Greek deities Poseidon and Artemis and the west Ara... |
If the salt water in the ocean accumulated over time was there ever a point where it was all freshwater? | Perhaps briefly (on a geological timescale), when the atmosphere cooled enough for the first rains to fall, the resultant bodies of water may have been pure enough to be considered freshwater with less than 500ppm of dissolved salts. There were almost surely multiple phases of the early Earth's surface water inventory condensing and then being boiled into the atmosphere again by the next major impactor, which would have left salt-flats behind that could be buried by lava and debris before the water recondensed, so that the salt left behind would have been cut off from the surface and wouldn't have quickly redissolved into the recondensing oceans. | [
"Scientific theories behind the origins of sea salt started with Sir Edmond Halley in 1715, who proposed that salt and other minerals were carried into the sea by rivers after rainfall washed it out of the ground. Upon reaching the ocean, these salts concentrated as more salt arrived over time (see Hydrologic cycle... |
why does adding salt to desserts make them seemingly sweeter? | Salt changes the electrochemical reactions that happen in the chemoreceptors on your tongue (taste buds). The effect is different for different types of receptors; bitter receptors are inhibited, while sweet receptors have their sensitivity enhanced. Sweet becomes sweeter and bitter becomes less bitter (but only up to a point; too much salt and you'll taste brine). | [
"Desserts can contain many spices and extracts to add a variety of flavors. Salt and acids are added to desserts to balance sweet flavors and create a contrast in flavors. Some desserts are coffee-flavored, for example an iced coffee soufflé or coffee biscuits. Alcohol can also be used as an ingredient, to make alc... |
why did a law need to be passed telling federal employees that they couldn't participate in insider trading? | This is how I understand it. Can someone please fill in the details or correct me on this?
Part of the reason is because, technically, a lot of what they were doing wasn't "insider" trading. Typically, insider trading happens (e.g.) when you work for a company or are someway involved in a company and you happen to know that your company did something good, so you and your buddies buy up a bunch of stock in advance of that public knowledge. There are other ways, but basically it's when you or someone you know has knowledge "inside" of a company.
There's plenty of that that went on in Congress as well, and still will. But what was happening was that Congress itself was the "insider". It knew it was about to pass a law that, say, hurt companies X, Y, and Z. So they took that knowledge and sold their shares or "shorted" them to make a profit off this knowledge.
Technically, this didn't have anything to do with having "inside knowledge" of a company's performance, financials, etc, so it was legal. It's still wrong, though, because it gives lawmakers a financial incentive to make laws one way or another that benefit them financially. | [
"U.S. insider trading prohibitions are based on English and American common law prohibitions against fraud. In 1909, well before the Securities Exchange Act was passed, the United States Supreme Court ruled that a corporate director who bought that company's stock when he knew the stock's price was about to increas... |
the future of computer storage: storage capacity vs compression abilities | So far, capacity has kept increasing rapidly. You used to buy the biggest drive you could afford, knowing that it was going to be filled up all too soon anyway, but that you'd be able to get a bigger one in a few years.
These days, the capacity of a hard drive tends to be much larger than anyone needs, especially with the offloading of capacity to the Internet. You can get your movies and songs online, so they're not eating your disk space.
Files are more typically compressed to reduce bandwidth, now, so they don't eat too much of your data line, although it's also still handy to reduce storage space. There's always this trade-off with compression, is the problem. It takes time to compress and decompress data.
I'd bet on drives getting larger and cheaper for the next decade or so. Barring a massive improvement in computer speed (unlikely) or cool new developments in compression algorithms (also unlikely), "more space" is still relatively easy at the moment. | [
"It is estimated that the total amount of data that is stored on the world's storage devices could be further compressed with existing compression algorithms by a remaining average factor of 4.5:1. It is estimated that the combined technological capacity of the world to store information provides 1,300 exabytes of ... |
Can a satellite maintain an orbit forever under ideal conditions? | Purely from Newtonian gravity - i.e., the gravity you learn about in high school - there's no decay under ideal conditions. But we've known that picture of gravity is wrong for nearly a century. The more modern theory, Einstein's theory of general relativity, allows for gravitational radiation, and any orbit will radiate away energy in the form of gravitational waves, slowly decaying over time. This resulted in one of the most impressive tests of general relativity, a [binary pulsar](_URL_0_) whose orbital decay was timed very accurately and found to be in precise agreement with the predictions for energy loss to gravitational radiation, winning its discoverers a very well deserved Nobel Prize. | [
"Each satellite has a design life of twelve years, with an orbital maneuver life of 15 years, which means that each satellite has been designed and fueled to maintain its assigned orbital position (within 0.1 degrees) for 15 years. After that point, the satellite must be decommissioned. The AfriStar satellite has d... |
Do satellites travel with the rotation of the earth or against and if they go both ways would two identical satellites going opposite directions at the same altitude have to travel at different speeds to maintain orbit? | Most satellites are in prograde orbits, meaning that they orbit in the same direction that the earth rotates. This is because retrograde orbits, which orbit opposite the direction of the earth's rotation, require more fuel to launch.
Think of it like this. If you're in a car going 5 mph and you want to get a projectile going 100 mph you can either throw it forward at 95 mph, or backwards at 105 mph. Obviously forward it easier. That 5 mph car is like the earth's rotation, and the 100 mph projectile (forward or backward, doesn't matter), is like orbital speed.
So unless you have specific launch requirements or orbits in mind, it's simply cheaper and more efficient to launch satellites into prograde orbits.
There are a handful of satellites on [retrograde orbits.](_URL_0_) Israeli satellites, for example, are launched westward so that launch debris would land in the Mediterranean rather than neighboring countries. This comes at the expense of a maximum payload that's [30% less](_URL_1_) than it would if it launched eastward- that weight is needed for fuel. Additionally, earth-observing satellites may be launched to be slightly retrograde so that they are on a sun-synchronous orbit. This enables them to have constant illumination from the sun when observing the earth.
| [
"Because a satellite in an eccentric orbit moves faster near perigee and slower near apogee, it is possible for a satellite to track eastward during part of its orbit and westward during another part. This phenomenon allows for ground tracks which cross over themselves, as in the geosynchronous and Molniya orbits d... |
Scientists: What is the coolest thing you've learned in your field? | I can make a big list actually, of moments I just had to stop and take a moment to digest that. Some of them:
1. The first time I saw the first division of a C. elegans embryo under a microscope. Its quite big so you can see all the aspects of cell division happening with your own eyes and its the most magical thing I've ever seen with mine.
2. The mechanisms with which chromosomes segregate, during mitosis. Especially once all the chromosomes are aligned up at the center of the cell, what the cell does is release a signal that will say, "all microtubules, DISSOLVE!". But the problem: the microtubules are what thats holding up the chromosomes there in the center and they can dissolve only in one direction. And the chromosomes need to keep attached to their ends. So as their ends dissolve, the chromosomes will follow them to seperate sides and the new cells form.
3. This [video](_URL_0_). I know I posted it elsewhere just today, but you can spend an entire degree just learning all the phenomena that are portrayed in every single frame of this video.
Could go on, actually. | [
"Described by Discovery as a \"commercial free hour of \"MythBusters\" mashups, hosted by Kari Byron\", the show features about ten minutes of new material—experiments and quizzes presented by Kari, as well as TV celebrity and scientist appearances, pitching the idea that \"science is cool\"—interwoven in fifty min... |
why is vibrato singing considered good? | Long notes can sound boring. Vibrato is intended to add some colour and variety during the course of the note.
Vibrato is a skill... but an equally important skill is knowing when and how to use it. It probably shouldn't be used in every note, or for the whole length of the note. The speed and the intensity of the vibrato can and should be varied, between as well as during notes. Basically, it shouldn't be predictable or boring, or else it defeats the point of using it in the first place.
Everything I've said here applies to pretty much all instruments on which vibrato is possible, by the way, not just voice. | [
"Vibrato is often perceived to create a more emotional sound, and it is employed heavily in music of the Romantic era. The acoustic effect of vibrato has largely to do with adding interest and warmth to the sound, in the form of a shimmer created by the variations in projection of strongest sound. A well-made violi... |
Was every desert once a body of water? | It's hard to say definitively whether or not every desert was once under a body of water, but desertification of once arable land is possible with poor land management, such as what happened with Africa after the Romans cut down all the trees. Sand is kind of always there, it's the vegetation and bio-mass that gets carried off by the wind due to the lack of moisture/life which makes the sand visible. It is therefore reasonable to assume that not all sand/deserts are made up of microscopic shell fragments such as those which could be found on beaches. One would assume it's mostly granulated rock, but it's also possible that the land was once underwater and the currents deposited a sediment bed before the land rose above the sea floor. | [
"Scientists agree that the existence of a desert in the place where the Sahara desert is now located is due to a natural climate cycle; this cycle often causes a lack of water in the area from time to time. There is a suggestion that the last time that the Sahara was converted from savanna to desert it was partiall... |
What happens to gut flora if a person is dying of starvation or dehydration? | Depending on where in the gut you're looking at, it may change. During starvation, your stomach acid may become more concentrated, and stronger - thus a small amount of bacteria in the proximal duodenum (small bowel coming right off the stomach) may be killed. This would be very minimal, since there are glands in the proximal duodenum that release bicarbonate and neutralize the strong stomach acid.
Further along, in the distal jejunum and ileum, and the colon let's say, I can imagine the flora there start to die off, since the job of this flora is to help break down various macronutrients (which for them is food), and during starvation, there is no more food reaching that far. Hope that answers your question | [
"The underlying starvation, malnourishment, and usually dehydration, associated with emaciation, affect and are harmful to organ systems throughout the body. The emaciated individual experiences disturbances of the blood, circulatory, and urinary systems; these include hyponatremia and/or hypokalemia (low sodium an... |
how were length/liquid measurements kept the same everywhere? | The short answer was, they didn't. Standards varied heavily from region to region. Keep in mind, back then, travel/trade was *a lot* harder, so the effects were much less noticeable.
In some cases, once things were more developed, they would have a standard- then they'd copy that standard and ship them around the world. But usually they were just really inaccurate.
If things were really really off, someone might call you on it, but slight variations, how would they know?It wasn't really until the industrial revolution and standards started being really important did things really start to kick in- largely driven because that's when it mattered | [
"Before the 1843 changeover, different units were used to measure length. One pic (dzera à torky) was equal either to 0.64 m or 0.623 m), while a different pic (dzera à rabry) was equal to 0.48 m or 0.467 m). Some other units are given below:\n",
"The history of the measurement of length dates back to the early c... |
Why can't you tame a Zebra? | "Taming" isn't all-or-nothing. There's a range of behaviors that includes whether the animal attacks humans, runs away from humans, tolerates being touched, tolerates various medical examinations and procedures, responds to commands, actively seeks human company, and so on.
The zebras at the San Francisco Zoo will do all of the things I just listed (with the possible exception of the last one) because of diligent training and regular reinforcement by their keepers.
But for safety's sake responsible zoos never describe their zebras as "tame". That would give a false sense of safety to the public. They may still attack an unfamiliar human. And this is true of horses as well. When working with even the tamest horse you never run up behind it and startle it because there's a good chance you'll take a hoof to the knee, or worse.
Source: I'm a long-time horse owner and friend of San Francisco Zoo keepers. | [
"Zebras have four gaits: walk, trot, canter and gallop. They are generally slower than horses, but their great stamina helps them outrun predators. When chased, a zebra will zig-zag from side to side, making it more difficult for the predator to attack. When cornered, the zebra will rear up and kick or bite its att... |
Is the earths ozone layer capable of changing position? | Well, the ozone layer is ubiquitous through the stratosphere. In fact, the predominant sources of ozone are in the tropics, and it's overturning circulations like the Brewer-Dobson that transport ozone to the poles through the year - at least until the polar vortex develops, which cuts off that transport.
You don't really get "ozone holes" over cities in the same sense as the famous ozone hole at the South Pole. That's because the primary mechanism for thorough ozone depletion - polar stratospheric clouds - do not occur anywhere except for in the Antarctic during their winter, and *occasionally* in the Arctic in its respective winter.
So no - it's not possible for a polluter to "create an ozone hole" in a local sense and have it move around to impact a non-polluter. Ironically, a bigger air-quality issue is the generation of ozone or ozone-precursors itself! For instance, polluters that emit PAN (peroxyacetyl nitrate) create non-local ozone pollution. PAN is relatively stable, and can be transported long distances before it breaks down to release NOx; that NOx can react in chemical families with volatile organic compounds to produce ozone as a byproduct of oxidation of the organic species. | [
"The ozone hole is usually measured by reduction in the total \"column ozone\" above a point on the Earth's surface. This is normally expressed in Dobson units; abbreviated as \"DU\". The most prominent decrease in ozone has been in the lower stratosphere. Marked decreases in column ozone in the Antarctic spring an... |
how does paypal make money/stay in business? | If you are a merchant selling something through them they take a 2.9% + $0.30 cut of your profit. | [
"PayPal's services allow people to make financial transactions online by granting the ability to transfer funds electronically between individuals and businesses. Through PayPal, users can send or receive payments for online auctions on websites like eBay, purchase or sell goods and services, or donate money or rec... |
Three questions about the Napoleonic army. | During a campaign, an officer was generally allowed a small Wagon to carry personal effects and anything necessary for his work in the field. This would range from a tent and necessary notes to liquor and personal reading. Naturally the higher the rank the more you'd be able to have bit the more you'll also need for your own command (maps, rosters, etc).
The main people to have a Wagon would be *chief De batalion* whom commanded a battalion (the smallest unit of independent command) on up. High ranking commanders would get a larger baggage train as they'd be allowed more personal effects and need more things relevant to their command.
However one thjng that officers were not allowed to have was wives. While this wasn't allowed, this didn't mean that it did not happen. Generally wives never accompanied commanders, commanders would take mistresses (such as Marshals Soult and Massena during their command of the Pininsular campaign).
As for horses, generally officers would be on horseback while moving but leading from the front (if that was their choice as not all commanders were the ideal leaders like Lannes or Oudinot) on foot. The reason of not being on horse has more to do with being a larger target for sharpshooters and the chance of having a horse (expensive for a lower ranking officer) dying and even falling on you if you're on it when it dies.
I hoped this helped, for more information on the organization of the French Army I'd recommend looking at Swords Around A Throne by John Elting, a very accessable and cheap book. | [
"Napoleon led a new army to the Battle of the Nations at Leipzig in 1813, in the defence of France in 1814 and in the Waterloo Campaign in 1815, but the Napoleonic French army would never regain the heights of the Grande Armée of June 1812.\n",
"Under Napoleon I, the French Army conquered most of Europe during th... |
What people does the Assyrians descend from? | This is a somewhat controversial topic within the Syriac christian community. Basically there are two main schools of thought: those who identify as Assyrians and descendants from the ancient Assyrians and those who identify as Arameans and their descendants. I will let someone with the 'Assyrian' origin point of view post that since I'm not as well versed in their various arguments but I will provide you with the basic 'Aramean' origin arguments, however first I'm going to go on a slight tangent that is necessary for this topic. Up till the 20th century, the Syriac Christians called themselves in Arabic 'Suryani' which originally meant 'Syrian'. Suryani was not only a term exclusive to Christians but also exclusive to those Christians not of Arab ancestry (the arabs christians were usually Greek Orthodox, Greek Catholic, or Maronite). During the 20th century however, nationalist ideals started among the Arab Christians of 'Al-Sham'(the Arab term for the Levant meaning "land of the North"), and at the helm of this nationalist movement was Antun Saddeh, a Greek Orthodox arab christian. In his movement, the arab christians who identified as 'al-shami' (meaning arab of al-sham), started to adopt the name 'suri' an invented term that was equated with Syrian in English therefore causing great confusion. The 'Suryani' response was to change the translation from Syrian to Syriac. So for the purposes of this post I will be using Syriac, and take in mind that it means 'Suryani', unless I specify that I mean the Syriac language.
The main idea of the Aramean origin argument goes as this: The Syriac christians, are descendants of the people called Arameans, a group of northwestern semites closely related to the Hebrew and Phoenicians, who during the bronze age collapse settled the land they called Aram. Later on, due to outside influences, namely Greek confusion on the matters of the people they saw as barbarians as they saw all non-Greeks, the name 'Syria' was invented either from a)the Coptic word for Hurrians translated to Greek or b)the Luwian-Hittite word for Assyrians translated to Greek (note that despite there being a greek word for Syrian, the Greeks also had a word for Assyrian, therefore complicating the matter even further). During this confusion the Greeks and later on the Romans would use the name 'Syria' without any solid meaning to refer to people of the near east/fertile crescent region who spoke aramaic. However, during that time, the Arameans continued to identify as Arameans until a gradual process started that was most likely in tandem with the rise of Christianity(which was after all spread by Hellenized Jews who spoke Greek), where they started to called themselves 'Syriac' in their native Aramaic. Eventually, the term 'Syriac' would be used to apply exclusively to the people of Aramean ancestry. So the name Syria would be applied to the former lands of Aram, which makes sense since the Syriac Church was based in Antioch, a city nowhere near ancient Assyria. So due to the fact that Arameans adopted the name 'Syriac', anyone who identified as such was an Aramean whether or not they came from areas like Mosul or Nineveh which thousands of years earlier were considered the Assyrian heartland. They back this up with evidence that during the Iron Age, Arameans settled in large numbers in the Levant and a region of Mesopotamia called Aram-Nahrain (Nahrain meaning "of the rivers", possibly a callback to the bronze age kingdom of Mitanni which was from the same area of Mesopotamia, that was called Nahrain by some peoples), which was just north of the Assyrians. The Assyrians on several occasions held massive deportations of Arameans (as well as other peoples such as Jews), not out of the empire, but into its capital. It is claimed that Aramean numbers grew so large that Aramaic replaced Akkadian, and Arameans grew to outnumber the native Assyrians. The origin of the modern Assyrian identity would be in the works of 17th/18th(not sure which one) century western missionaries who upon finding the Syriac christian communities of Iraq, claimed based on archeological grounds that they must be the descendants of the ancient Assyrian, confusing the meaning of 'Suryani'.
Let me know if anything needs clarification, however, I will restate that I expect someone else to post the Assyrian side of this, as I do not want to misrepresent my post as one sided. | [
"In Church tradition, the Assyrians are descended from Abraham's grandson (Dedan son of Jokshan), progenitor of the ancient Assyrians. Along with the Arameans, Phoenicians, Armenians, Greeks and Nabateans, they were among the first people to convert to Christianity and spread Eastern Christianity to the Far East.\n... |
you know how you can tense up certain muscles in your foot or leg and pretty immediately give yourself a cramp? why do your muscles have those 'pressure points' or non-random cramp areas, and why is it so easy to bring about a cramp in them? | I tried to read up on this, and also asked my doctor about it, and it seems to not be totally known, in part because there can be a lot of different reasons depending on the person and circumstances.
I think these are usually technically muscle spasms rather than cramps, although they're similar.
Some possible causes:
- Dehydration
- Electrolyte depletion (usually salt, sometimes potassium and maybe magnesium)
- Muscle overload
That last one is probably what's going on -- it seems like it is most likely to happen with highly underused muscles (or overused muscles in people who work out a lot)
Of course there are also (a zillion) medical conditions that can cause cramps or spasms.
Googling found this page that looks ok at first glance:
_URL_0_ | [
"A cramp is a sudden, involuntary muscle contraction or over-shortening; while generally temporary and non-damaging, they can cause significant pain, and a paralysis-like immobility of the affected muscle. Onset is usually sudden, and it resolves on its own over a period of several seconds, minutes or hours. Cramps... |
how can the hubble space telescope keep its lens pointed in the same spot to take long exposure shots when it's orbiting the earth every 97 minutes? | Hubble uses six gyroscopes to know exactly where it's pointing. These are devices that act a bit like a compass, and always point in the same direction even when the telescope is orbiting.
Next it has four reaction wheels which actually move the telescope. These just use Newton's 3rd law of motion; if the wheel spins one way then the telescope spins the other.
Finally when it's observing, an instrument called the Fine Guidance Sensor will lock on to nearby stars, and make sure the telescope stays precisely pointed in the same direction/orientation. | [
"The Hubble Space Telescope has three fine guidance sensors (FGSs). Two are used to point and lock the telescope onto the target, and the third can be used for position measurements - also known as astrometry. Because the FGSs are so accurate, they can be used to measure stellar distances and also to investigate bi... |
what do fireworks event companies do the rest of the year? how do they stay profitable? | Sporting events mostly. A lot of minor league baseball teams have displays at the end of weekend games. Same with other sports as well. | [
"Fireworks Entertainment was an independent studio founded by Jay Firestone in 1996 to produce, distribute and finance television shows and feature films. Fireworks was acquired by Canwest Global in May 1998, and was later sold to ContentFilm (production company of The Cooler), a British company, in April 2005. Ove... |
Why didn't land animals evolve to dinosaur size again after their extinction? | From our [FAQ](_URL_5_) (which I wrote, hence the copypasta):
There have been much larger terrestrial mammals in the past. [*Paraceratherium*](_URL_6_) is an example. There are also mammals alive today that are as large or larger than the largest dinosaurs (blue whales!). However, the fact remains that some dinosaurs - particularly sauropods - were absolutely monstrous. They may not have been blue whale-sized, but they were surprisingly close, and they were terrestrial. It's hard to know exactly what allowed some dinosaurs to grow so big. Sauropods, the largest dinosaurs. had a few adaptations that seemed to [give them a a size advantage](_URL_2_):
- Their long necks were effective for eating lots of plant material with minimal energy expenditure.
- They almost certainly had a [unidirectional airflow system](_URL_10_) in their lungs because both birds (theropod dinosaurs) and crocodylians (the only other living archosaurs) both have that. This uses countercurrent flow to bring oxygen into the circulatory system. It's part of why birds are so successful as well.
- They had heavily pneumatized skeletons that made them relatively lightweight for their massive size (something mammals don't have).
In contrast, terrestrial mammals seem to have both a [limit to how quickly they can increase their body size](_URL_8_) and a [maximum body size](_URL_7_). What causes these constraints is hard to say. The study on maximum body size found that the largest mammals evolved when during periods of global cooling and when there was more terrestrial land area. There seems to be physiological and ecological constraints on their maximum size, because several herbivore groups independently evolved to similar maximum sizes, as did several carnivore groups.
As for why terrestrial animals are generally smaller today, there was an extinction event at the end of the [Pleistocene](_URL_3_) that [disproportionally affected the terrestrial megafauna](_URL_4_). Nearly 2/3 of animals larger that 44 kilograms that were present 50,000 years ago were extinct by 10,000 years ago.
It took millions of years for terrestrial animals to have that huge increase in size after the Cretaceous-Paleogene extinction, but terrestrial mammals largely filled that role. Given how geologically recent these extinctions are, it's extremely unlikely that anything would have been able to fill the gaps left by the loss of megafaunal mammals. In that sense it's completely expected that a recent extinction event would leave a gap in body size.
One thing that does *not* explain maximum body size is atmospheric oxygen levels. There were already large sauropods by around 190 million years ago, around where [this graph](_URL_9_) bottoms out. One example is [*Barapasaurus*](_URL_0_), a 14-meter-long early sauropod from the Early Jurassic. So [whatever led to their gigantism](_URL_1_) was present when oxygen levels were lower than today, not higher. The study looking at body size in mammals also found no relationship to atmospheric oxygen levels. | [
"BULLET::::- Archibald argued that the withdrawal of shallow seas from Earth's continents during the Late Cretaceous reduced the size of and fragmented the coastal plain habitats preferred by large dinosaur species and that this fragmentation may have driven some taxa extinct.\n",
"After the Cretaceous–Paleogene ... |
what is computer science? | So, this rundown is my own, and the idea here is to have a pseudo-historical list running in descending order of abstraction. Basically, I'll start with the most abstract and general ideas of the field, and work down towards nitty gritty practical bits that emerged.
But anyway, the main idea of computer science is to deal with processes, and specifically, unlike mathematics, processes that have extra limitation that you need to be able to perform them in a finite amount of time and space. Because, you know, humans have only limited amount of time to wait for computation to finish, and there's only finite amount of the universe we have access to.
So, in computer science specifically, what was a rather important point was that sometimes you have these processes be in the form of step-by-step lists of instructions(hereby called "algorithms") that even the stupidest could follow. So we built the stupidest thing, and we called it artifical computer(as opposed to computer of the old, who were humans, mostly women, performing calculations as required for some fields of science and engineering and such), and tried seeing what we can do with this concept. So now the question of study became, what can these artifical computers actually do. Some major results were achieved in 1940's, specifically Alan Turing was helpful, where he managed to prove some key things about things that can be computed, and perhaps more importantly, that there were some things that couldn't.
And as computer technology advanced, computers itself started to become more complex, and the programs running on them started to require more and more sophisticated thinking, and computer science basically absorbed things like software engineering to itself, taking it further away from pure math world. Things like, what sort of tradeoffs you'd have when designing operating system fit neatly in this world of questions that more or less deal with what can and cannot be done with computers.
But much of the discussion is still well within confines of pure math as well. Say, computational complexity is a measure of algorithms ability to use fewer steps to arrive at the right answer. You don't need to ever even have seen a computer to be able to answer questions about those kinds of things, and it's ultimately about processes and algorithms rather than this physical device, although limitations of this physical device did end up sparking interest in these types of questions. Likewise, "formal language theory" is basically mathematics, but that theory is the main way to understand programming languages, and the theoretical foundation for their existence. So the line gets blurred. I'm unsure but I believe linguistics also makes an appearance here in this multi-dispiclinary mess. Another field that I want to highlight for math'iness is artifical intelligence. Also, worth noting that encryption basically is just taking mathematical problems we can prove are hard in one way but easy in another.
And then you also have fields that are more specifically about using computers, like user interface design, or user experience design, which start invoking psychology and such things.
And obviously, physical design of computing devices with its electrical engineering, physics and chemistry connections has to be mentioned.
Basically, it started out with a rather simple premise of "what this box do?" and then when the box turned out to be very powerful, the field just exploded to cover everything the box touched. | [
"Computer science is known by its near synonyms, like Information Technology (IT) and Computing. At the beginning, only a few students can get computer science education, but as time passes, it’s popular in ordinary people. In UK, in 1981, only A level students can get it, but in 2014, even common pupils can study ... |
What defines the maximum and minimum wavelength of electromagnetic radiation? | There is no maximum or minimum wavelength, any wavelength can be transformed into another one with the right choice of reference frame. A possible exception to this is if quantum gravity breaks Lorentz symmetry, and then there will be some minimum Planck-scale wavelength. | [
"The electromagnetic spectrum extends from below frequencies used for modern radio to gamma radiation at the short-wavelength end, covering wavelengths from thousands of kilometers down to a fraction of the size of an atom. That would be wavelengths from 10 to 10 kilometers. The long wavelength limit is the size of... |
when i wake up at 3 am to pee, why does keeping my eyes closed for my trip to the bathroom seem to help me get back to sleep faster? | Your brain has this thing called a circadian rhythm. What it's designed to do is make you sleepy at night time and wakeful during the day. Unfortunately, your body doesn't have a clock inside of it so it has to rely on cues outside of you to know when it's night and when it's day. One of the cues your body uses is light. When you see a bright light at night (awesome sentence) it confuses your brain and makes you more awake.
Note: This is a big simplification but you get the idea. | [
"\"Urinating in bed is frequently predisposed by deep sleep: when urine begins to flow, its inner nature and hidden will (resembling the will to breathe) drives urine out before the child awakes. When children become stronger and more robust, their sleep is lighter and they stop urinating.\"\n",
"Mowrer detailed ... |
When a hot surface (a grill) is radiating hot air, why is there distortion in the air above it? | The angle at which air refracts light changes based on density. There is a temperature and density gradient between the hot grill and relatively cool surrounding air. | [
"Convection causes the temperature of the air to vary, and the variation between the hot air at the surface of the road and the denser cool air above it creates a gradient in the refractive index of the air. This produces a blurred shimmering effect, which affects the ability to resolve objects, the effect being in... |
Is there any evidence that essential oils actually do anything other than smell good? | Essential oil simple means that is possess a smell similar to the plant it is derived from. It isn't based on anything medical related. Now that doesn't mean that they arn't good for you, it just means that it is a large category that isn't related to anything medical. Its sort of like asking if the category food is good for you. The quality that makes something food doesn't entail it being healthy, but some food can be healthy. You would have to research each individual product to say if it is good for you or not. If someone has a study like that on a broad level they may be able to dismiss them all together. | [
"Essential oils are volatile and liquid aroma compounds from natural sources, usually plants. They are not oils in a strict sense, but often share with oils a poor solubility in water. Essential oils often have an odor and are therefore used in food flavoring and perfumery. They are usually prepared by fragrance ex... |
how do they move sculptures that are to big for trucks? | > Edit: ah dicks, forgot ELI5
Ha. It's ok. It's still evident this is a legit ELI5 question.
I really wish there were a better answer, but they pretty much just [close down all the roads](_URL_0_). It's super inconvenient (which is why they try to do it late at night).
LA has something of a habit of frequently inconveniencing its citizens by bringing in massive boulders, sculptures, and even space shuttles. | [
"The articulated haulers relatively small size also make them able to drive on public roads between different worksites at a large construction project—something that is impossible for the largest haul trucks, which might even have to be disassembled to be moved between different locations. For transportation betwe... |
Does "alcoholism" or "alcoholic" have a scientific definition, or is it a more subjective term? | The DSM-IV-TR has definitions for alcohol abuse and alcohol dependence - [link](_URL_0_).
It's important to note that (a) The DSM V is due very shortly and (b) There are many researchers who feel that the DSM does not use the best model.
In regards to your question, it's worth noting that the criteria are a combination of subjective and objective symptoms. This is common for mental health conditions and one of the more common criticisms. If you lined up 100 therapists and asked them all to tell you whether 100 regular drinkers had a disorder, there would be *some* level of agreement but not total agreement. In nature, all mental health diagnoses are somewhat subjective and therefore open to interpretation by sufferers and diagnosticians. | [
"The term \"alcoholism\" is commonly used amongst laypeople, but the word is poorly defined. The WHO calls \"alcoholism\" \"a term of long-standing use and variable meaning\", and use of the term was disfavored by a 1979 WHO expert committee. \"The Big Book\" (from Alcoholics Anonymous) states that once a person is... |
how can an aircrafts engine work at such high altitudes where humans struggle to breathe due to lack of oxygen? | The aircraft require less power at high altitude because of less air resistance but very few aircraft can operate at very high levels due to the lack of air. | [
"The human body can adapt to high altitude through both immediate and long-term acclimatization. At high altitude, in the short term, the lack of oxygen is sensed by the carotid bodies, which causes an increase in the breathing depth and rate (hyperpnea). However, hyperpnea also causes the adverse effect of respira... |
What are the heat related consequences of urination? | When urine leaves your body it is body temperature. Your body either heats, or is heated, by the cold or hot food and liquids you eat. Urinating itself does not change your body temperature as you are evacuating this temperature stabilized liquid. | [
"The temperature at which the urine is examined is a very important factor to consider in the process of uroscopy. When a patient urinates, the urine will be warm, so it is necessary for it to stay warm for proper evaluation. The external temperature should be the same as the internal temperature. When the temperat... |
why does the western world (say usa and western europe) get involved in armed local conflicts all over the world even if it doesn't have to? | Several reasons.
1) We have interconnected economies. So having trade access to resources means that some conflict that you would not think would affect a country really do affect them.
2) We now have invented weapons that are capable of destroying civilization as we know it with a push of a button. Limiting who gets the knowledge to make these weapons, and watching those countries that do have the knowledge is important and it often means going into war or smaller conflicts to prevent the spread of that knowledge.
3) Much of the world powers attempted to practice the philosophical stance of letting countries do whatever they want in their borders and to their neighbors and only getting involved when there was direct threat to them. What happened was the build up of Germany and start of WWII. | [
"There is significant debate over whether the lack of any major European general wars since 1945, is due to cooperation and integration of liberal-democratic European states themselves (as in the European Union or Franco-German cooperation), an enforced peace due to intervention of the Soviet Union and the United S... |
What portion of the world's current gold supply was part of Atahualpa's ransom? | Let's assume that Hernando Pizarro was telling the truth about the size of the ransom and that all the promised ransom was received. Here is the description from Hernando Pizarro
> for that he could give them ten thousand plates, and that he could fill the room in which he was up to a white line, which was the height of a man and a half from the floor. The room was seventeen or eighteen feet wide and thirty-five feet long.
We'll start with the room. Assuming that the average height of a man was 5 feet, that would make the volume of the room to the line 17ftx35ftx7.5ft. 4462.5 cubic feet. One cubic foot of gold weights 1206 lbs so the total amount in the room would have been, accounting for open space, less than 5,381,775 lbs of gold. There is approximately 280,000,000 lbs of gold above ground in the world. So that would make it about 1.9%.
[Here](_URL_1_) is a picture of silver Incan plates, let's assume the gold ones Pizarro describes are the same size. They are not very big, so let's put their weight at 2 pounds. That would add 20,000 lbs of gold to the ransom which even at 10 lbs a plate is a negligible amount compared to the world's gold supply.
* Sources:
* _URL_2_
* _URL_0_
* _URL_3_
| [
"In 1532, Francisco Pizarro was paid a ransom amounting to a roomful of gold by the Inca Empire before having their leader Atahualpa, his victim, executed in a ridiculous trial. The ransom payment received by Pizarro is recognized as the largest ever paid to a single individual, probably over $2 billion in today's ... |
Why was the practice of presenting men, who refused to enlist in the army, a white feather supported by early feminist organizations? | The so-called 'Order of the White Feather' was created in Britain in 1914 by a former admiral, and essentially involved handing out 'white feathers' to anyone, specifically men, not seen as supporting the war effort, ie not enlisting. Some British women's organizations handed out feathers, an act that symbolizes 'cowardice' on the part of the receiver and which predated WWI. However, they seem to have been a minority, [with Stephen Badsey indicating that most references to them he's seen from the time being in the context of complaints against their activities.] (_URL_0_) It would seem their activities were curtailed, and by 1915 Compulsion had been introduced under the Derby Plan, and eventually Conscription was introduced at the beginning of 1916. The appearance of the White Feather seems to have died out by 1916, which seems to suggest a correlation with Conscription being enacted.
It's also worth noting that few men before conscription enlisted purely on compulsion; the Derby Plan netted 80 000 in 1915, the roughly same number as that of volunteers in August 1914. [Compare this again to the over 100 000 men that volunteered in the first fortnight of September 1914, following the publishing of the Mons Dispatch.] (_URL_1_)
If you want some good sources on wartime Britain (1914-1918), I'd highly recommend *The Last Great War: British Society in the First World War* by Adrian Gregory, *A Kingdom United* by Catriona Pannell, *Myriad Faces of War* by Trevor Wilson and *Different Wars, Different Experiences* by Janet K Watson. | [
"Despite their obvious distinctions from men, women were eager to volunteer. Many of the servicewomen came from restricted backgrounds; therefore they found the army liberating. Other reasons women volunteered included escaping unhappy homes or marriages, or to have a more stimulating job. The overwhelming reason f... |
In the Byzantine Empire, what type of names did people have? | That depends on the time period and location. Up until around the sixth century, you can see a lot of emperors having Latinate names, like Flavius Sabbatius Iustinianus (not that I'm biased!), Constantinus, or Iulianus. Later, more Hellenic names appear, like Basileios the Bulgar-Slayer or Alexios Komnenos. It's worth noting that those two are usually anglicized and latinized, respectively, as Basil and Alexius Comnenus. Now, since the Byzantine heartland was around the southern Balkans and Anatolia, Greek names would dominate the lower classes in much of the Empire. At its further reaches, one could also find Slavs, Armenians, Arabs, and others. Furthermore, in Constantinople there existed a large Italian presence thanks to the merchant republics.
Again, though, you're asking about a period of roughly a thousand years and an area covering much of the eastern Mediterranean. It's hard to generalize. | [
"Many peoples neighboring on the Byzantine Empire used names expressing concepts like \"The Great City\", \"City of the Emperors\", \"Capital of the Romans\" or similar. During the 10th to 12th century Constantinople was one of the largest two cities in the world, the other being Baghdad.\n",
"Of Byzantine origin... |
To what extent did the Soviet-Polish war cause Poland to be successfully invaded in 1939? | The Polish army was strong for a country of its economical development - it was well trained and equipped with modern arms. However, they were unable to stand up to the full power of a grand power such as Germany, and even less the power of two grand powers (Germany and the Soviet Union).
The Soviet-Polish war and the Polish gains in it earned it the enmity of the Soviet Union. It already had the enmity of Germany due to existing partially on previously German land that the Germans wanted back. It also had the enmity of Lithuania, since it had annexed the city of Vilnius and the area around it.
Czechoslovakia and Poland also had a strained relationship, since Czechoslovakia had used the timing of the Polish-Soviet war to grab the contested area of Teschen from Poland.
Poland had friendly relations with Romania and France though.
As you can see from this, the Polish-Soviet war placed Poland in a strategic and diplomatic vice from which it could not escape. Once Germany and the Soviet Union came to an agreement, there was very little the Poles could do to change their situation. | [
"The Polish–Soviet War (February 1919 – March 1921) was an armed conflict between Soviet Russia and Soviet Ukraine on the one hand and the Second Polish Republic and the short-lived Ukrainian People's Republic on the other. The war was the result of conflicting expansionist ambitions. Poland, whose statehood had ju... |
why is perpetual energy from gravity impossible? | Gravity pulls things down. You can exploit this for energy, but only once.
Once the object has exhausted its "gravitational potential" (i.e. hit the ground) you can't extract any more without first picking it up again.
We do extract energy from falling water in hydroelectric dams, but again the water can only pass the dam once. | [
"Gravity also acts at a distance, without an apparent energy source, but to get energy out of a gravitational field (for instance, by dropping a heavy object, producing kinetic energy as it falls) one has to put energy in (for instance, by lifting the object up), and some energy is always dissipated in the process.... |
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