Split (2)

train · 226k rows

question stringlengths 3 301	answer stringlengths 9 26.1k	context list
So,cancer cells which collectively form tumors have the property of attracting blood vessels from the sourrounding matrix (angiogenesis) for nutrition and other purposes right?Then why can't doctor's simply remove those vessels and kill the tumor instead of radio and chemotherapy?	Sometimes they can. Cancers can be incredibly complex things though and it's very often not that neat and tidy. Cancers are so diverse to begin with there's no straight answer to the question in it's current form.	[ "Most tumors of visceral blood and lymphatic vessel walls are cancerous (malignant). Because these cancers are carried by the blood flow or lymphatic flow, they can more easily metastasize to distant sites, particularly the liver and lungs.\n", "Tumors induce blood vessel growth (angiogenesis) by secreting variou...
what force stops things going faster than light?	Nothing. Calling this speed 'the speed of light' is not helpful. It is the maximum speed, the speed that defines 'time', the maximum speed of the universe. It so happens that one of the things that travels at that speed is light. As an object nears the speed of light, its mass will increase. (This happens at all speed...	[ "When an object is pushed in the direction of motion, it gains momentum and energy, but when the object is already traveling near the speed of light, it cannot move much faster, no matter how much energy it absorbs. Its momentum and energy continue to increase without bounds, whereas its speed approaches (but never...
What does a chameleon's field of vision look like when it's eyes are pointing in different directions?	My brother has had vision problems all his life. His eyes work independently, i.e. he doesn't fuse the images from his eyes but, instead, has two entirely separate images. In elementary school, they asked him to look into a machine and tell them whether the ball was on or off the picnic table. He was very confused. He ...	[ "The angle, or amplitude, of eye movement in chameleons is very large for a vertebrate and the eyes move independently of each other. This allows a chameleon to watch an approaching object while simultaneously scanning the rest of its environment. Chameleon eyes protrude laterally from the head, giving the lizard p...
since we have satellites, why is it debated whether russia has entered ukraine illegally?	Because Russia simply denies it. US already published a lot of pictures of Russian convoys that entered Ukraine, Russian artillery firing into Ukraine, etc. "X claims" is just a polite and neutral way to say things in media. For most of the world Russian army invaded Ukraine and they accept it as fact. Russia still ...	[ "A number of Russian citizens reported that they have been denied European visas after they visited Crimea after annexation. A Russian consumer protection watchdog OZPP published a warning for Russian tourists about this risk, explaining that from the international law point of view, Crimea is an occupied territory...
why there are no sky-colored birds?	For the most part, birds are safe in the air (the exception being from some birds of prey which usually strike from above, not below). Birds are vulnerable when on the ground, so it makes more sense to blend in with their usually terrestrial habitat than the sky. Or they are brightly colored to attract a mate, simply b...	[ "BULLET::::- However, the colours of these birds may be brighter to the birds themselves since birds are tetrachromats and can see colours in the ultraviolet range that are invisible to humans, who are trichromats.\n", "Some of these birds are difficult to identify because of the similarity between species, and v...
How do scientists know the earths tilt changes every 41,000 years?	It was predicted in the 19th century and [was actually measured in '76](_URL_0_) As to why this happens: The Earth's orbit is an ellipse. The eccentricity is a measure of the departure of this ellipse from circularity. The shape of the Earth's orbit varies in time between nearly circular (low eccentricity of 0.0...	[ "In addition the tilt, or obliquity, of the Earths axis is not constant but changes in a cycle of its own. During a cycle that averages about 40,000 years, the tilt of the axis varies between 22.1 and 24.5.\n", "The angle of the Earth's axial tilt with respect to the orbital plane (the obliquity of the ecliptic) ...
Since some species of goats faint, is that considered normal behavior or is this a disorder?	These goats have myotonia congenita, a disorder of skeletal muscle which causes prolonged contraction in response to stimuli. In the case of fainting goats, the breed is descended from a few goats brought to Tennessee in the 1800's, and is a heritable mutation which has been sustained because people breed them because ...	[ "Fainting goats have a muscle condition called myotonia congenita. Myotonia congenita is a mutation in the genes that affect the skeletal muscles which cause a . This is a condition that occurs in many species, including humans. The goats do not truly \"faint\" in any sense of the word, as they never lose conscious...
lucifer's fall from grace in christian mythology	Lucifer was the highest one of the angels, almost their leader (tho not quite obviously). But he was becoming too proud and selfish, and attempted to take seat in god's throne. god cast him down, and with him fell about a third of the armies of heavens. (Now demons). Actual biblical references are few and controverse ...	[ "Some Christian writers have applied the name \"Lucifer\" as used in the Book of Isaiah, and the motif of a heavenly being cast down to the earth, to Satan. Sigve K Tonstad argues that the New Testament War in Heaven theme of Revelation 12 (), in which the dragon \"who is called the devil and Satan … was thrown dow...
how come spacesuits don't inflate like balloons due to the unequal pressure?	They actually do. They have rigid ribbing so they hold their shape, so you don't see it/notice it that much when you see them on TV. But they do inflate in as much as the flexible parts in between the rigid parts will allow.	[ "Like a droplet, bubbles are round because cohesive forces pull its molecules into the tightest possible grouping, a sphere. Due to the trapped air inside the bubble, it is impossible for the surface area to shrink to zero, hence the pressure inside the bubble is greater than outside, because if the pressures were ...
Light: refractive indices and Snell's law	The wavefronts must line up along the boundary. If the incident light forms a nonzero angle with the normal, then its wavefronts have nonzero velocity along the plane between the two media. Snell's law gives the correction required for the wavefronts in the refractive medium to line up with the wavefronts in the inci...	[ "Snell's law is used to determine the direction of light rays through refractive media with varying indices of refraction. The indices of refraction of the media, labeled formula_6, formula_7 and so on, are used to represent the factor by which a light ray's speed decreases when traveling through a refractive mediu...
why did we invade iraq for possibly having wmds but have ignored north korea, who actually has wmds and is willing to use them?	It is a lot easier to bully countries trying to get WMDs, than countries that actually have WMDs.	[ "How did Saddam let the world believe Iraq had WMD by denying he had WMD? How does this story work? It doesn't, because the [Associated Press] report is false. FBI agent Pinto's actual record of a casual conversation with Saddam reads: \"Even though Hussein claimed Iraq did not have WMD, the threat from Iran was a ...
Facial expressions - surprise, fear, anger - nature or nurture?	[Dr. Paul Ekman](_URL_2_) has published many articles regarding universal expressions and emotions. [The universality of the 6 basic emotions](_URL_0_) suggest that there are some emotions that are expressed irregardless of environmental stimuli. His writings suggest [there are approx. 10,000 different possible expre...	[ "Emotional contagion is linked to facial mimicry in humans and primates. Facial mimicry is an automatic response that occurs in less than 1 second in which one person involuntary mimics another person's facial expressions, forming empathy. It has also been found in dogs at play, and play sessions lasted longer when...
In Star Wars, on Tatooine you can see two suns that are fairly big in the horizon. Would two stars that close completely burn up the planet?	To answer that, you would have to know the relationship between apparent brightness, size, and temperature. Scaling the size, temperature, and distance of either star would affect how it appeared from the planet. Without knowing those relationships, I can't give you an exact answer. Generally, I would think that the b...	[ "In their controversial article (see above) Collins and his colleagues make another suggestion: on the morning of 4 July, the star ζ Tauri was not bright enough and too low on the horizon to be visible. If the guest star, which was located close to it, was visible, it is only because its brightness was comparable t...
how can energizer claim to make some of their new batteries from recycled batteries, when consumers cannot (to my knowledge) recycle their aa batteries?	They use the depleted chemicals in old batteries to create fresh chemicals for new batteries. Better than creating the chemicals from scratch every time	[ "As a result, most retailers who sell rechargeable and other special batteries will take the old ones back for free recycling and safe disposal. The not-for-profit Rechargeable Battery Recycling Corporation (RBRC), used by most retailers, reclaims the metals within the old batteries to make new products such as bat...
Does having smaller eyes allow you to see smaller things?	this was a popular question a few months ago: _URL_0_	[ "Sometimes the needs for visual acuity in different functions conflict, and different parts of the eyes may be adapted to separate functions; for example, the Gyrinidae spend most of their adult lives on the surface of water, and have their two compound eyes split into four halves, two for underwater vision and two...
how do music services know what songs i will like and what songs fit together?	Every company has a slightly different recipe, AKA algorithm, but in most cases, it comes down what other people like. Let's say you have one song that you listen to a lot. Well, the algorithm knows that thousands of people who like that song also like this song. Or, perhaps those two songs have appeared on hundreds of...	[ "While listening, users are offered the ability to buy the songs or albums at various online retailers like iTunes or Amazon. More than 450 musical attributes are considered when selecting the next song. These 450 attributes are combined into larger groups called focus traits, of which there are 2,000. Examples of ...
What's the deal with sub-Saharan Africans and slavery?	Deal? 1 per small barrel of cowry shells.	[ "Before the Atlantic slave trade there were already people of African descent in America. A few countries in Africa would buy, sell, and trade other enslaved Africans, who were often prisoners of war, with the Europeans. The people of Mali and Benin are known for partaking in the event of selling their prisoners of...
Is pure H2O corrosive?	No. Water is simply not very reactive stuff--the hydrogen and oxygen have already combined violently, giving off lots of energy. In fact, if you submerge iron in a sealed container of distilled water, it won't rust. The misconception that pure water is corrosive seems to come from the way it's handled (no metal pipes....	[ "Hydrogen cyanide (HCN), sometimes called prussic acid, is a chemical compound with the chemical formula HCN. It is a colorless, extremely poisonous and flammable liquid that boils slightly above room temperature, at . HCN is produced on an industrial scale and is a highly valuable precursor to many chemical compou...
why do youtube pranksters need consent from the prankees to have their face shown if they're in public when the filming occurred?	It's not illegal to tape them in most places when there's no expectation of privacy. However, those individuals still have an implicit copyright claim on their image, and reproducing it could open them up to legal action.	[ "The process of writing and developing the pranks and stunts for the film took two years, and it was filmed in 30 days. In addition, they had guest writers from \"Punk'd\" helping them advance concepts. Atwood said they developed 400 pranks overall, but only ended up using about 32 in the movie. The trio had to get...
Why does thinking take time?	Thinking is a chemophysical reaction in your brain. Your brain neurons function through ionic potential. They use electricity, created by chemical reactions, to move information from one part of the brain to another, and eventually to your muscles (although it is not quite the same as electricity flowing down wires). ...	[ "Although time is regarded as an abstract concept, there is increasing evidence that time is conceptualized in the mind in terms of space. That is, instead of thinking about time in a general, abstract way, humans think about time in a spatial way and mentally organize it as such. Using space to think about time al...
why do you feel drained of energy when you get a shot?	We get shots to help defend us against viruses and these shots tend to have that viruses weaker little clone in them. You body has to build up a familiarity with this and learn to defend against it, so your immune system goes to work. It's not like being sick, but it's close enough that your body diverts resources to t...	[ "BULLET::::- The battery effect; the cells in the body have the same function as batteries, being charged with energy that comes from an outer source. This is most often seen in gamma exposed individuals such as the Hulk, who get their powers from this stored energy. The powers will remain as long as the energy is ...
if the universe is expanding, aren't new stars being born all the time? and i guess they would be even if it wasn't, so why is it said that the universe will be completely dead one day?	The idea is that, while the universe is expanding in size, the amount of matter and energy in it is finite. That whole, can't be created or destroyed thing. What happens when you have a set amount of something in a container that's getting bigger? Eventually the universe will be so massive and stretched out that th...	[ "If the expansion of the universe continues and it stays in its present form, eventually all but the nearest galaxies will be carried away from us by the expansion of space at such a velocity that our observable universe will be limited to our own gravitationally bound local galactic cluster. In the very long term ...
is it possible for our brains to get tired from thinking or studying too much like our muscles do when we exercise? if yes, how?	Mental fatigue can be hard to quantify and exact physiology isn't fully understood. Most of the activity in your brain is the result of neurotransmitters being released and binding to receptors. Things like acetylcholine, dopamine, serotonin, etc. Some of these neurotransmitters can become depleted and slow things d...	[ "Exercise fatigue has also been attributed to the direct effects of exercise upon the brain such as increased cerebral levels of serotonin, reduced level of glutamate secondary to uptake of ammonia in the brain, brain hyperthermia, and glycogen depletion in brain cells.\n", "Physical exercise rapidly triggers sub...
What caused Vienna to become a giant in architecture, art, and music during the early 1800's until the early 1900's?	It's also interesting to note that Vienna didn't necessarily "produce" all those talents, but did provide opportunities for many people born outside the city - Beethoven (Bonn), Mozart (Salzburg), Mahler (Kalischt, Bohemia), and Oskar Kokoschka (Pochlarn, Lower Austria)for example.	[ "From the late-19th century to 1938 the city remained a centre of high culture and of modernism. A world capital of music, Vienna played host to composers such as Brahms, Bruckner, Mahler and Richard Strauss. The city's cultural contributions in the first half of the 20th century included, among many, the Vienna Se...
why can you eat egg yolk raw and not get sick but not egg whites?	Bacteria can get into eggs via two methods: first, the chicken can have an infection inside their reproductive organs, and the bacteria get into the egg before the shell is formed. Second, the chicken can get poop (and therefore bacteria) on the eggs by sitting on them or if the area where they lay them is contaminate...	[ "Although egg whites are prized as a source of low-fat, high-protein nutrition, a small number of people cannot eat them. Egg allergy is more common among infants than adults, and most children will outgrow it by the age of five. Allergic reactions against egg white are more common than reactions against egg yolks....
why is it 'politically risky' for a us politician not to take a pro-israel stance?	The US has a tremendously powerful and influential lobby of Jewish people and interests. Any politician that comes off as anti-Israel will have a lot of rabbis knocking on their door. Further, a lot of businesses that are owned or influenced by that lobby will think twice about funding their next election campaign.	[ "Michael Lerner suggests that some United States politicians are reluctant to criticise Israel because they are afraid of being labelled anti-Semitic. Lerner also states that groups that promote peace in the mid-East are afraid to form coalitions, lest they be discredited by what Lerner terms the \"Jewish Establish...
the new definition of gender	In most western culture, we have two genders (basically social roles) which we line up with the two sexes (biological bits). But there are some cultures with more than two* genders. The [Fa'afafine](_URL_0_) in Polynesia and [Hijras](_URL_1_ in India are well-known examples. The issue for us is that gender and sex ha...	[ "In the \"Oxford English Dictionary\", \"gender\" is defined as, \"[i]n mod[ern] (esp[ecially] feminist) use, a euphemism for the sex of a human being, often intended to emphasize the social and cultural, as opposed to the biological, distinctions between the sexes.\", with the earliest example cited being from 196...
I heard of Barbary corsairs kidnapping people into slavery as far away as Iceland. What were the circumstances of these kidnappings (i.e. why did they go so far just to find captives for the slave market), and did they make any material contributions to cartography or exploration in their time?	The reason they went so far to get slaves has to do with the politics of the Mediterranean at the time. The Barbary States were totally dependent on slavery for every aspect of their economy. Slaves generated revenue from ransom, sale between individuals, and as free laborers. From time to time, the powers of the Med...	[ "While Barbary corsairs looted the cargo of ships they captured, their primary goal was to capture people for sale as slaves or for ransom. Those who had family or friends who might ransom them were held captive, but not obliged to work; the most famous of these was the author Miguel de Cervantes, who was held for ...
what exactly is going on with american isps at the moment?	American government lawyer here...studied Aviation and Outer Space law in Canada. My Outer Space law professor put it best (paraphrased) when discussing telecoms...for capitalism to work you need both corporations and government regulators. When only one is working well the people are getting screwed. Conservatives ...	[ "In 2005 there were more than 180 ISPs operating in the country. ISP's are regulated by the BTRC. In 2016, there were 119 licensed ISPs providing services nationwide and 65 ISPs providing services in the central zone.\n", "\"The company got its start in Costa Mesa, California around 1994 when its entire staff con...
what was the first state in history to create a constitution?	This depends on your definition of "constitution." One could argue the Magna Carta, or even the collective Peace of Westphalia, but I believe that in its modern definition, it was the Netherlands _URL_0_.	[ "Before the Constitution was drafted, the nearly 4 million inhabitants of the 13 newly independent states were governed under the Articles of Confederation and Perpetual Union, created by the Second Continental Congress, first proposed in 1776, adopted by the Second Continental Congress in 1778 and only finally una...
besides wages and licensing fees, where does the money go to when developing a game and why has it become so much more expensive to do so?	More man hours of wages than before - Games simply take more time and bigger teams than they did in the past. Way back when lots of games were either one man teams or a very small group. Watch the credits for any AAA title now and you'll see that's not the case. Marketing - Games are a bigger, more competitive busines...	[ "Salaries for game programmers vary from company to company and country to country. In general, however, pay for game programming is generally about the same for comparable jobs in the business sector. This is despite the fact that game programming is some of the most difficult of any type and usually requires long...
how does electronic currency mining work?	Simplified, with bitcoin, the "coins" are a long chain of solutions to a convoluted math problem. Each coin has to be discovered mathematically by computing out the problem, and it's designed so that each new coin's problem is harder than the one before, and that only a set number of coins will be discovered. After t...	[ "\"Mining\" is a record-keeping service done through the use of computer processing power. Miners keep the blockchain consistent, complete, and unalterable by repeatedly grouping newly broadcast transactions into a \"block\", which is then broadcast to the network and verified by recipient nodes. Each block contain...
What where the US founding Fathers motivations behind the second ammendment?	The video is not necessarily wrong. The short answer is, it's a bit more complicated than that, but since the second amendment is a source of never-ending heated debate, it is slightly more difficult to see the forest through the trees, as they say. There were a couple of main reasons for the second amendment. One was ...	[ "By their actions, the Founding Fathers made clear that their primary concern was religious freedom, not the advancement of a state religion. Individuals, not the government, would define religious faith and practice in the United States. Thus the Founders ensured that in no official sense would America be a Christ...
Is virtual reality possible?	We should be able to make man-made devices that send sensory signals directly to the brain (already done actually); and also be able to read the motor signals the brain sends in order to control your hands, legs etc. So you would be able to just lay in your bed and experience, say, Middle Earth. If you wanted to run, y...	[ "Virtual reality (VR) is a simulated experience that can be similar to or completely different from the real world. Applications of virtual reality can include entertainment (i.e. gaming) and educational purposes (i.e. medical or military training). Other, distinct types of VR style technology include augmented rea...
What determines what color skin an animal has?	There are any number of factors which can determine why (evolutionarily speaking) an animal's skin is one color or another. Climate is certainly one of the environmental factors, but it's not necessarily the only one in play. It depends greatly on the particular animal in question and how its genes respond to its ha...	[ "Animal skin coloration often comes about through specialized cells called chromatophores, which animals such as the octopus and chameleon can control to vary the animal's color. Many conditions affect the levels or nature of pigments in plant, animal, some protista, or fungus cells. For instance, the disorder call...
How prevalent was domestic violence in the United States before 1960? Was spousal and/or child abuse (as we would recognize it today) ever the norm in the United States? Was it ever expected that a man would hit his wife?	This does not speak to prevalence, mind, but toward the interpretation of child abuse in American history. Not well-versed in the subject, but saw this had no answer. Beyond the obvious underreporting of child abuse, there were racial and class dynamics that came into play, particularly through gonococcal vulvovaginit...	[ "A 1969 study of labor conflict violence in the United States examined the era following the 1947 passage of the Taft-Hartley Act, and concluded that violence had substantially abated. In the 16 years from 1947 through 1962, 29 people died in labor conflicts, a rate much lower than in previous eras. The study noted...
what does fdic ensured checking or investment account mean? and what are some things it does not cover?	FDIC checking accounts came into being to give assurance to banking. In the great depression there was a lot of fear and people pulled their money out of banks en masse because they were afraid it wouldn't be there when they needed it, which actually caused it to be unavailable to everyone else. This is called a "ban...	[ "A guaranteed investment contract (GIC) is a contract that guarantees repayment of principal and a fixed or floating interest rate for a predetermined period of time. Guaranteed investment contracts are typically issued by life insurance companies qualified for favorable tax status under the Internal Revenue Code (...
Does light attenuate?	Theoretically in a perfect vacuum, electromagnetic waves do not loose energy when they propagate. This agrees with the law of conservation of energy. But then, you may ask, why is it that radio signals or light signals are weaker the farther away you go? That is because the waves "spread" out, so while the total energ...	[ "BULLET::::- \"Quadratic\" () – This is how light intensity decreases in reality if the light has a free path (i.e. no fog or any other thing in the air that can absorb or scatter the light). For a given point at a distance x from the light source, the light intensity received is proportional to .\n", "The other ...
why is horse manure considered a good natural fertiliser? why doesn't the horse make use of the nutrients in it?	Manure is rich is Nitrogen which plants require for creating amino acids which are in turn used for growth and repair. If the soil the plant was grown in had a lack of nitrogen then the plant would display deficiency symptoms of poor growth and yellow leaves. As for why the horse doesn't make use of the nutrients in t...	[ "Animal manure, such as chicken manure and cow dung, has been used for centuries as a fertilizer for farming. It can improve the soil structure (aggregation) so that the soil holds more nutrients and water, and therefore becomes more fertile. Animal manure also encourages soil microbial activity which promotes the ...
why is a court allowed to tell people they should attend a 12 step program if they are atheist?	> Step 2, believe in a higher power. But I don't. In AA, "higher power" is purposefully vague so that it doesn't have to mean "God". From Wikipedia: > In current twelve-step program usage a higher power can be anything at all that the member believes is adequate. Reported examples include their twelve-step group, ...	[ "In the United States, psychologist and lawyer Stanton Peele has encouraged legal action against mandated attendance of 12-step programs, stating an objection to the courts and other government and tax-supported agencies mandating attendance at meetings run by organizations with spiritual or religious content. They...
Were there any flight skeptics in the scientific community before the development of mechanical flight?	When you say 'mechanical flight' are you referring to heavier-than-air craft like airplanes and helicopters, or flying machines in general, like manned balloons and blimps?	[ "George Cayley studied flight scientifically in the first half of the 19th century, and in the second half of the 19th century Otto Lilienthal made over 200 gliding flights and was also one of the first to understand flight scientifically. His work was replicated and extended by the Wright brothers who made gliding...
why is it impossible to find any video of most of the olympics?	NBC purchased exclusive rights to the Olympics, therefore any other company/site trying to broadcast/stream the events was legally infringing on NBC's rights. The only way to watch the events online in the US was login through NBC's site (having a username/password for an existing cable TV service was required - presum...	[ "Organizers of major tournaments are usually the point of contact for acquiring footage of underwater hockey matches. Although no official worldwide repository exists for recorded games, there are many websites and instructional DVDs. A wide variety of related footage can be found on video sharing sites.\n", "Bec...
If meat going bad is really just bacterial waste on the surface, why can't it be washed to an edible condition?	At home, you may be able to wash or trim most bacteria off the surface of a contaminated piece of meat, and cooking to a proper temperature (well-done) will kill off the internal bacteria, but neither will destroy the toxins that the bacteria have already produced. The toxins are what give "off" meat a foul taste and...	[ "Eating deteriorated food could not be considered safe due to mycotoxins or microbial wastes. Some pathogenic bacteria, such as \"Clostridium perfringens\" and \"Bacillus cereus\", are capable of causing spoilage.\n", "Bacteria are responsible for the spoilage of food. When bacteria breaks down the food, acids an...
for a disease that cause sores (chicken pox, hfm etc), what determines where the sores pop up?	For each type of skin disease there are different patterns and different reasons for the patterns. For viruses that infect nerve cells (like shingles, which is the chicken pox virus) the pattern comes out in [dermatomes](_URL_0_) or the pathway of the nerves that they infect. For some infections, it depends on the ...	[ "The prepatellar bursa and the olecranon bursa are the two bursae that are most likely to become infected, or \"septic\". Septic bursitis typically occurs when the trauma to the knee causes an abrasion, though it is also possible for the infection to be caused by bacteria traveling through the blood from a pre-exis...
what would happen to firewalls if google were to make a vpn service?	If Google were to do this, the user would have a different IP address from the site itself.	[ "Security experts quoted by the BBC indicated that well-written firewall rules can filter out most traffic from DDoS attacks by LOIC, thus preventing the attacks from being fully effective. In at least one instance, filtering out all UDP and ICMP traffic blocked a LOIC attack. Because internet service providers pro...
is genetic engineering possible to an adult?	Kinda, we can work with Recombinant DNA to insert certain genes on certain cells so they produce a protein that they are not producing, but should. One example would be getting pancreatic cells to produce insunline on a diabetic patient. [I'll leave you this video](_URL_0_)	[ "Human genetic engineering has advanced to the point that anyone—single individuals, same-sex couples, groups of three or more—can reproduce. The embryos can be allowed to be developed naturally, or they can undergo three levels of tinkering: \n", "The kind of technology used in genetic engineering is also being ...
while driving, how is the whistling sound created by the narrow window slit?	similar to you whistling. you pass air in very tiny space, increasing its speed, which produced noise, the faster it goes the higher the pitch.	[ "BULLET::::- WhistleHigh pitched often very loud screaming and screeching created by the resonance of gas. This is caused by a very fast strobing (on/off burning stage) of the fuel. The rapid bursts of gas from the fuel vibrate the air many hundreds of times per second causing the familiar whistling sound. It is no...
explain how percentiles work?	"Per cent" means out of 100. Suppose you have 100 apples, and you rank them from most fresh to most rotten. The freshest apples would be the top 10 percent (the top 10 out of 100), and the most rotten would be the bottom 10 percent (the bottom 10 out of 100).	[ "A percentile (or a centile) is a measure used in statistics indicating the value below which a given percentage of observations in a group of observations falls. For example, the 20th percentile is the value (or score) below which 20% of the observations may be found.\n", "The percentile rank of a score is the p...
why does light leave a trail in pictures with moving light sources?	The light travels to the camera and it leaves an imprint, but it does not happen in an instant. There is this thing called shutter speed, which I think means how long the camera receives the picture. This is a nice example (from Hungarian Wikipedia): [_URL_1_](_URL_0_) So, I think it leaves a trail because picture ta...	[ "Light trails is another photographic effect where motion blur is used. Photographs of the lines of light visible in long exposure photos of roads at night are one example of effect. This is caused by the cars moving along the road during the exposure. The same principle is used to create star trail photographs.\n"...
Why was Germany considered an empire and France a kingdom?	Because the formation of Germany happened after Napoleon separated the idea of the title of Emperor being inherently Roman. By disbanding the Holy Roman Empire and crowning himself Emperor of France(not Roman Emperor) Napoleon set the precedent for rulers to style themselves Emperor regardless of the historicity of the...	[ "Germany was a latecomer in the Empire Race, which was already well underway when the country was unified in 1871. Germany, like other European powers, wanted the honor and prestige of having a colonial empire. German foreign policy in that period was intensely nationalistic; it changed from \"Realpolitik\" to the ...
Do wind powered generators slow wind down enough to have an environmental impact?	Not at the moment. A couple of months ago there was an article that (claimed to have) calculated that something like 50.000 turbines of the coast could slow down a hurricane enough to cause less damage. [NOAA](_URL_0_) says a hurricane has 1.5TW of energy, a single turbine can convert 3MW of that into ele...	[ "Ion wind generators and wind turbines share some of the same advantages and disadvantages. Both are subject to the conditions of the wind, and are unable to generate electricity if the weather conditions are not favorable. This can be mitigated to some degree with strategic placement of the devices in areas with m...
why is it important to turn off your eletronical devices (especially computers) ?	Electronics more frequently die during a power up or power down scenario, as power supplies often spike during these events. I turn my LCD displays off when not in use, since their vacuum fluorescent back-lights have a limited life (40,000 hours MTBF) but keep my computer powered on. I do clean out the dust twice per y...	[ "One method of dealing with the switching of unneeded components is called clock gating, which involves turning off the clock signal to unneeded components (effectively disabling them). However, this is often regarded as difficult to implement and therefore does not see common usage outside of very low-power design...
Smiling helps produce hormones such as serotonin and dopamine, but does aggressive and masculine behaviour increase testosterone production?	> does aggressive and masculine behaviour increase testosterone production? First, I'd question the hell out of your implicit assumptions. "Aggression" and "testosterone" are neurologicaly antithetical - "roid rage" is induced by testosterone withdrawl. It's not unreasonable to wonder if your ideas of "masculine"...	[ "Many studies implied that testosterone level were one of the key factors in aggressive competitive behaviour in social situations. When testosterone is produced in the brain and gonads in both genders, the androgen receptors in neural and peripheral tissues are being possessed and trigger behavioural and physiolog...
alternative minimum tax	The alternative minimum tax is a tax calculation that acts as a second tax floor when it comes to calculating the amount owed on federal income taxes. It is calculated differently than the typical "standard deduction." Whichever is higher (standard income tax rate vs alternative minimum tax) in $$ is the one you have...	[ "The alternative minimum tax (AMT) is a supplemental income tax imposed by the United States federal government in addition to baseline income tax for certain individuals, corporations, estates, and trusts that have exemptions or special circumstances allowing for lower payments of standard income tax. AMT is impos...
[Physics] as there are anti-matter equivalents of sub-atomic pieces, could there an anti-electromagnetic spectrum?	No. Unlike protons, neutrons, and electrons, photons are their own antiparticle, so "antilight" is the same thing as light.	[ "Some particles, such as the photon, are their own antiparticle. Otherwise, for each pair of antiparticle partners, one is designated as normal matter (the kind all matter usually interacted with is made of), and the other (usually given the prefix \"anti-\") as \"antimatter\".\n", "Note that if \"n\" and \"n\" a...
why do arms crossed over chest considered to be a denial? i personally find just comfortable.	A closed posture like having crossed arms is a body language indication that the person is unavailable or unreceptive to what's being said. People also tend to cross their arms when they're upset or disagree with the other person so it gets read subconsciously as a negative	[ "This can be a difficult concept for many people to identify with in themselves, but is a major barrier to changing hurtful behaviors. Denial of denial involves thoughts, actions and behaviors which bolster confidence that nothing needs to be changed in one's personal behavior. This form of denial typically overlap...
What kind of sexual pleasures did Roman emperors Tiberius and Caligula engage in that made them so notorious?	Both Tiberius and Caligula were disliked by the social elite, who wrote the history books and biographies that we draw our information from. This means that our sources (and their sources!) are known to be hostile and should not be taken at face value. The major sources for this period are Cassius Dio, Tacitus and Su...	[ "While Tiberius was in Capri, rumours abounded as to what exactly he was doing there. Suetonius records the rumours of lurid tales of sexual perversity, including graphic depictions of child molestation, and cruelty, and most of all his paranoia. While heavily sensationalized, Suetonius' stories at least paint a pi...
why are movie drug manufacturers always in their underwear?	Generally to keep them from stealing anything. If you don't have pockets or privacy, it is much more difficult to steal.	[ "At the time, pharmaceutical companies were making considerable money by selling drugs under their trade names, giving out biased information about the branded drugs as against those named generically. Doctors often prescribed branded drugs, which were far more expensive than generic drugs, which have the same effi...
If the Earth was shrunken down to the size of a marble but still had the same mass, would it form a black hole? How much mass would a marble need to have to form a black hole?	We don't exactly know how big a black hole is. The math says it has zero volume (a singularity), but we don't know what happens to the physics in these situations. What we do know is, given a certain amount of mass, how big the radius is of the sphere that encompasses the region from which light can't escape. This rad...	[ "A small mass has an extremely small Schwarzschild radius. A mass similar to Mount Everest has a Schwarzschild radius much smaller than a nanometre. Its average density at that size would be so high that no known mechanism could form such extremely compact objects. Such black holes might possibly be formed in an ea...
When a new human being is created how do the cells know they need to develop organs like the brain in our bodies?	An embryo has three stages of development, the zygote stage, the embryo stage and the fetus stage. During the earliest stage, the zygote begins as a single cell as a result of the fusion between two gametes or "haploiod cells", these haploid cells form a diploid cell. This means it has a unique genotype. The unique g...	[ "In 1998, Fred H. Gage (Salk Institute for Biological Studies, La Jolla, California) and Peter Eriksson (Sahlgrenska University Hospital, Gothenburg, Sweden) discovered and announced that the human brain produces new nerve cells in adulthood. Until then, it had been assumed that humans are born with all the brain c...
What specifically causes the death of someone with Fatal Familial Insomnia (Or SFI)?	Other comments here may be overstating the role of direct, prion-related cell death on the lethality of FFI, although it is almost certainly a part of the story. Backing up a bit, animal studies of chronic insomnia in healthy, wild-type animals have demonstrated that [sleep deprivation alone can be lethal](_URL_0_). ...	[ "Fatal familial insomnia is a hereditary prion disease in which degeneration of the thalamus occurs, causing the patient to gradually lose his ability to sleep and progressing to a state of total insomnia, which invariably leads to death. In contrast, damage to the thalamus can result in coma.\n", "Fatal familial...
How has nuclear weapons technology advanced for modern times?	The last big breakthroughs in nuclear weapons development were made in the early 1960s and were implemented in weapons through that period to the late 1980s, when US warhead development essentially stopped. They involve making very small thermonuclear warheads. These innovations (the details are classified but there ha...	[ "This timeline of nuclear weapons development is a chronological catalog of the evolution of nuclear weapons rooting from the development of the science surrounding nuclear fission and nuclear fusion. In addition to the scientific advancements, this timeline also includes several political events relating to the de...
[Chemistry] Is it possible to tell the physical state of a single atom (solid, liquid, gas)?	It is not possible. States of matter refer to how particular atoms/molecules interact with one another. For example, a solid is considered a solid because the molecules form rigid bonds with one another. With only one molecule, the concept of bonding to other molecules has no meaning.	[ "A solid state example is the palladium-hydrogen system which has a solid solution phase (H in Pd) in equilibrium with a hydride phase (PdH) below the UCST at 300 °C. Above this temperature there is a single solid solution phase.\n", "A chemical state can exist on or inside the surface of a solid state material a...
in quantum mechanics, how is it possible for nothing to exist until it is observed?	It's not that the object doesn't exist. It's that the state/property of the object is unknown until observed.	[ "In the everyday world, it is natural and intuitive to think of everything (every observable) as being in an eigenstate. Everything appears to have a definite position, a definite momentum, a definite energy, and a definite time of occurrence. However, quantum mechanics does not pinpoint the exact values of a parti...
why is it so hard to think about a song while listening to a different one?	Selective attention. As much as we wish we could pay attention to more than one thing at once, or multi-task, we literally can't, our brains aren't built for it.	[ "Research suggests we listen to the same songs repeatedly because of musical nostalgia. One major study, published in the journal Memory & Cognition, found that music enables the mind to evoke memories of the past.\n", "Brain Fair has stated that, \"This song is about how people, TV, and other influences can conv...
Can a 4-D object spin in two directions?	Mathematically, yes. 4 dimensions is the first vector space in which two independent rotations can occur without them summing to a single rotation in a single plane. For instance, an object can spin in the XY plane and also in the ZW plane, simultaneously, and there is no single-"axis" spin which reproduces that moti...	[ "An interesting property of spin ½ particles is that they must be rotated by an angle of 4 in order to return to their original configuration. This is due to the two-to-one correspondence between SU(2) and SO(3) mentioned above, and the fact that, although one visualizes spin up/down as the north/south pole on the ...
why websites can show an "i'm down!" message when they're down?	There's a guy at school who talks to a lot of people. Some people tell him interesting things, and he has a very good memory, so if you're ever bored, you can go talk to him and he'll tell you one of their stories. As time progresses, this guy gets more and more popular, and starts to have trouble keeping up with dema...	[ "BULLET::::- Each viewer can create a \"blocking list\", which allow users to block some unwanted words or comments. There may be some unwanted comments shown on screen while watching videos, viewers can block the unwanted word or comment. The word or sentences would disappear on that viewer's screen. The others vi...
why is glass considered a super-cooled liquid but ice is considered a solid?	Glass has no structure to how the atoms are placed when it cools down. Glass is called an amorphous solid. When water cools down to ice, the atoms arrange in such a way that it has a set crystalline structure.	[ "Melting past its glass transition temperature (T) between 120 and 140 K, LDA is more viscous than normal water. Recent studies have shown the viscous liquid stays in this alternative form of liquid water up to somewhere between 140 and 210 K, a temperature range that is also inhabited by ice I. LDA has a density o...
Is inflation a really good indicator of past prices?	Could you clarify what you're asking? This is an economics question not a historical question. We need times and places in order to answer the question historically rather than theoretically.	[ "Inflation Measures: Decay in past economic production is implicitly accounted for by the adjustment from nominal to real GDP in historical statistics. Politically motivated biases may cause officially reported consumer price inflation (CPI), a major component of the GDP Price Deflator) to be lower than actual. For...
why is the sound bad if you call someone right next to you?	A few years ago, I used to work as a technician for a mobile operator. I would spend quite a bit of time testing handsets for call quality issues and suchlike, and so it was quite common for me to call colleagues who were sitting as close as the very next desk to try something out. For the most part, there's nothing w...	[ "Fear of making calls may be associated with concerns about finding an appropriate time to call, in fear of being a nuisance. A sufferer calling a household or office in which they know several people may be concerned at the prospect of failing to recognize the voice of the person who answers, with resultant embarr...
why does the pain from muscle-aches after gyming feel so good?	I think it's your brain releasing specific endorphins that feel good. I know that's what happens with a "runner's high", where your body floods with nice stuff to tell you that it's good that you are running and you should do it again.	[ "Discomfort can arise from other factors. Individuals who perform large numbers of repetitions, sets, and exercises for each muscle group may experience a burning sensation in their muscles. These individuals may also experience a swelling sensation in their muscles from increased blood flow also known as edema (th...
the bodies strewn around mount everest	> Whatever financial cost is outweighed by returning the bodies home 1. You're ignoring the potential cost of even more people dying on the mountain. 2. Not everyone there would have wanted their body to be returned home, and would consider being remembered forever as a marker on the mountain they strove to con...	[ "In 1935, Eric Shipton led a small reconnaissance expedition to Mount Everest. They found Wilson's body at the foot of the North Col, lying on its side in the snow and surrounded by the remains of a tent which had been torn apart by the elements. A rucksack containing his diary was found nearby. The body was buried...
why our congress is trying so hard to pass sopa.	_URL_0_ I watched hours and hours of the Congressional committees debates. They mentioned the need to fight piracy approximately once per minute. They mentioned tech jobs and startups perhaps once total. They mentioned public opinion and the will of the people zero times.	[ "On January 17, 2012, in response to growing concerns over PIPA and SOPA, the White House stated that it \"will not support legislation that reduces freedom of expression, increases cybersecurity risk, or undermines the dynamic, innovative global Internet.\"\n", "In December 2011, Representative Ron Paul spoke ou...
Why is freshly fallen snow more "packable" than older snow that's been on the ground for a while?	You're already onto the basics of packing snow - how wet it is matters a lot. If snow just sits on the ground for a while, several things can happen to it. The water can freeze, and melt again, and freeze again, and so forth. This plays havoc with "wetness" and "snowness", and it's next to impossible to get teh great ...	[ "These factors contribute to the metamorphism of snow, i.e. the process of reshaping snow crystals into smaller, more rounded ice grains, which in turn consolidates and settles the snow pack. Increased density increases strength by joining of grains though sintering and freezing of melted water. New-fallen snow may...
[Biology] How do we know specific dinosaurs only lived in certain periods?	Generally speaking any one species won't be found outside of a particular window of time last at most a couple million years. T. rex specifically is represented by about 50 distinct specimens all found near the end of the Cretaceous. For it to have lived for 80 million years since the Jurassic and leave no evidence, th...	[ "The Indian fossil record of dinosaurs is good, with fossils coming from the entire Mesozoic era – starting with the Triassic period (a geological period that started 251.9 million years ago and continued till 201.3 million years ago), to the Jurassic period (201 million years ago to 145 million years ago) and Cret...
why do doctors and physicians use balance scales instead of electronic ones?	> Those are balance scales; they are inherently more accurate, need less calibration, and are easier to calibrate if does become necessary, relative to electronic scales. Also matpavelle correctly observes they have built-in height measurement. [Reddit](_URL_0_)	[ "Balance theory is useful in examining how celebrity endorsement affects consumers' attitudes toward products. If a person likes a celebrity and perceives (due to the endorsement) that said celebrity likes a product, said person will tend to like the product more, in order to achieve psychological balance.\n", "V...
technocracy	A “technocracy” is when the government uses scientists and engineers to devise what is “best” rather than what people want. It doesn’t always mean literal leadership by scientists. Often it refers to a regime that believes technology and rationality can solve social problems. The upshot is that the technocracy insti...	[ "The term \"technocracy\" is derived from the Greek words τέχνη, \"tekhne\" meaning \"skill\" and κράτος, \"kratos\" meaning \"power\", as in \"governance\", or \"rule\". William Henry Smyth, a California engineer, is usually credited with inventing the word \"technocracy\" in 1919 to describe \"the rule of the peo...
What's the science behind Mozart helping babies develop and helping people study? Is it just Mozart, or all classical music?	The idea that playing Mozart to babies will make them more intelligent is a myth, or at least not scientifically accepted. It seems to stem from a study in the 90's finding college students who had recently listened to Mozart outperformed a control group on a spatial reasoning task. Media misreporting turned this into ...	[ "BULLET::::- Popularized versions of the hypothesis, which suggest that \"listening to Mozart makes you smarter\", or that early childhood exposure to classical music has a beneficial effect on mental development;\n", "Mozart in many ways did not need a mentor by the time he met Haydn; he was already rather succe...
Why does vertical striping appear when a laser is shined on a camera?	Looks like your laser pointer is pulsed. Rather than being constantly on, it quickly turns the light on and off repeatedly. When the frequency of the pulses is high enough, our eyes don't notice it. If you move that laser really quickly across a featureless wall, you might notice that the laser trace varies in brightne...	[ "In the basic technique, using strip photography, a camera with a vertical slit aperture is positioned opposite a turntable on which an object is centered. Both the object and the camera are oriented as precisely as possible so as to eliminate aberrations due to the focusing mechanism of the camera, the aperture, a...
why mobile phones require pin after boot, even when fingerprints/irises/faces are registered?	A pin is also used as an encrypt/decrypt key after reboot and the fingerprint is used as for ease of authentication only. You cant use fingerprint after reboot as the biometric info is stored in the encrypted state.	[ "A mobile phone may be PIN protected. If enabled, the PIN (also called a passcode) for GSM mobile phones can be between four and eight digits and is recorded in the SIM card. If such a PIN is entered incorrectly three times, the SIM card is blocked until a personal unblocking code (PUC or PUK), provided by the serv...
how to write a symphony?	Nice try, Salieri	[ "A symphony is an extended musical composition in Western classical music, most often written by composers for orchestra. Although the term has had many meanings from its origins in the ancient Greek era, by the late 18th century the word had taken on the meaning common today: a work usually consisting of multiple ...
how do spacecrafts not melt off through launch if the temperature in the exosphere is 1700 degrees celsius?	For ~~temperature~~ HEAT in the atmosphere you can look at [this chart](_URL_0_). As you can see, generally tends to decrease, and at no point is it hotter than at ground level, except when you factor in sunlight, where ~~temperatures~~ HEAT may reach 128ºC. Even then, that's VERY far from the 1700ºC this guy mentions....	[ "During the spacecraft's fall toward earth, a solid-fuel Antares II rocket behind the payload fired for 30 seconds, increasing the descent speed to 40,501 kilometers per hour. Instruments in the spacecraft radioed temperature data to the ground. The spacecraft exterior reached an estimated temperature of 11,400 K. ...
I heard in an interview with Brian Greene that according to string theory space can "tear," so what is space made of and what is getting "torn?"	I guess he's talking about the topology of the compactified part of spacetime changing. Roughly, the topology of a geometrical object (like a doughnut or a universe) means anything which is not changed by continuous deformations. One aspect of the topology of an object is the number of "handles" it has, so a coffee...	[ "According to John Horgan, science journalist writing for \"The Wall Street Journal\", Hawking, in his book, prefers string theory as a way of explaining the \"theory of everything\" (which Hawking predicts to be solved by \"the end of this century\") and, based on quantum mechanics, considers empty space as filled...
Breathing and heartbeats both occur passively. Why can we stop ourselves from breathing but not our heart from beating?	First, let's briefly talk about the heart. The heart itself is controlled by its internal pacemaker (assuming everything is working as it's supposed to). That 'pacemaker' is the [sinoatrial node](_URL_3_). Under 'normal operating conditions', the SA node is doing its own thing, triggering your heart to beat ~80 times/m...	[ "Breathing has other important functions. It provides a mechanism for speech, laughter and similar expressions of the emotions. It is also used for reflexes such as yawning, coughing and sneezing. Animals that cannot thermoregulate by perspiration, because they lack sufficient sweat glands, may lose heat by evapora...
why does a car's recommended tire pressure depend on the car, not on the tire?	The weight of the car determines the required pressure All tires have the same sized contact patch at ideal pressure. Narrow tires have a square patch while wide tires have a very rectangular patch, but both have the same area. This constant area times the tire pressure will equal the weight of the car. A heavy car w...	[ "Air pressure within a tire forces its beads against the wheel rim and normally ensures that the tire and rim rotate as a single unit. In general automotive situations, a tire's air pressure is sufficient to withstand dislodging and rim-slip forces experienced during, respectively, hard cornering and acceleration (...
Why didn't america retain it's territorial gain from the Spanish American war?	At least in the Pacific, the US also took the Philippines and Guam as a result of the Spanish-American War. The Island chains in the Pacific I think you may be referring to are the Marianas and Caroline Islands which were not taken by the US (though they would become governed by the US later and for other reasons). I...	[ "In the Spanish–American War, Spain lost many of its remaining colonies. In the Pacific, the United States took possession of the Spanish Philippines and Guam. On January 17, 1899, the United States also took possession of unclaimed and uninhabited Wake Island. This left Spain with the remainder of the Spanish East...
why is it easy to keep a beat but it's difficult to count 'seconds' accurately in your head?	As a musician, I find it harder to count seconds because my mind unconsciously takes into account the number of syllables in the second and I get thrown off balance. With beats it's just tik-tok-tik-tok-tik-tok or something similar, with seconds it goes ...five-six-*SEVEN\-eight-nine-ten-ELEVEN\-twelve-**TH...	[ "The accuracy of beat and section recognition depends upon the recording in ways that are sometimes hard to predict. Sequenced tracks with a strong beat almost always work well, but very busy or heavily compressed tracks or those with irregular rhythms can drift in and out of time, making some of the automatically ...
the senate torture report	[Please search before asking](_URL_0_)	[ "On 21 December, the ACLU released further documents documenting tortures. Notably, in a case of shooting of suspects without warning, Army commanders are reported to have interfered with the investigation. Procedures of autopsy of detainees who died in unclear circumstances have been canceled by battalion and grou...
Did the Spartans have lambdas on their shields?	We don't know as much about Spartan shields as we'd like. I've written about the various possibilities as to their colour [here](_URL_0_), which also includes a bit about the lambdas. The main point is that only one source, a fragment from a lost comedy by Eupolis, actually proves this practice, by using the metaphor ...	[ "The letter \"lambda\" (Λ), standing for Laconia or Lacedaemon, which was painted on the Spartans' shields, was first adopted in the 420s BC, and quickly became a widely known Spartan symbol. Military families passed on their shields to each generation as family heirlooms. The technical evolution and design of Spar...
Traditional black holes happen where something is so dense that it has such a strong gravitational pull that not even light can escape from it. Could there be, theoretically, black holes caused by one of the other four fundamental forces?	Such an object would affect only things that interact with that force, so only charged objects for the electromagnetic force, or objects with colour charge for the strong force, etc. Even though they might never be able to escape, light still could. Quark pairs are sort of analogous to this: if you try to pull them ap...	[ "Steinhardt, Spergel and Jason Pollack have proposed that a small fraction of dark matter could have ultra-strong self-interactions, which would cause the particles to coalesce rapidly and collapse into seeds for early supermassive black holes.\n", "As more mass is accumulated, equilibrium against gravitational c...
What was the name of the Japanese campaign, during the Second Sino-Japanese War, that opened up a land link between occupied China and Indochina?	The offensive was called Operation Ichi-Go (April to December 1944). It consisted of three separate battles in the Chinese provinces of Henan, Hunan and Guangxi. It did result in a lot of conquered Chinese territory for the Japanese and the loss of B-29 bases to the Americans. But although it was a tactical victory fo...	[ "Japan launched multiple attacks in East Asia. In 1937, the Japanese Army invaded and captured most of the coastal Chinese cities such as Shanghai. On 22 September 1940, the Japanese invasion of French Indochina began. Japan took over French Indochina (Vietnam, Laos, Cambodia), British Malaya (Brunei, Malaysia, Sin...
Did nobody read Mein Kampf prior to 1938?	Some people did take Hitler's threats quite seriously. There were plenty in the Soviet Union who were aware of Hitler's stated intentions and the nature of his regime. Most notably, Bukharin, always the most Western-looking of the Bolshevik leadership, was familiar both with Mein Kampf and how it sat within the incre...	[ "Nazi Propaganda Minister Joseph Goebbels read the book in early August and immediately grasped its value, writing in his diary: \"This Jew did a real service for the enemy [German] side. Had he written this book for us, he could not have made it any better.\" Under Goebbels' direction, \"Germany Must Perish!\" con...
Was there any chance for Portugal to take the strait of Gibraltar during the Reconquista?	[Strait of Gibraltar](_URL_1_) is a body of water between Europe/Spain on the northern side and Africa/Morocco on the southern. In medieval (and modern for that matter) times the key cities were Gibraltar, Tarifa and Algeciras on the Europe side, and Ceuta, Tangier, Arzila and Alcácer Ceguer on the Africa side. Dependi...	[ "At the same time, the Portuguese forces were also involved in the \"Reconquista\", successively advancing south to reconquer territories occupied by the Moors. The Portuguese part of the \"Reconquista\" came to an end in 1249, with the complete recapture of the Algarve.\n", "Portugal, Castille and Aragon were al...
Why are simple covalent molecules of the same element not all diatomic?	The stability of both chemical molecules and atoms themselves often depends on what is energetically favourable. If a molecule is the lowest energy configuration of a certain element under certain conditions, then it won't suddenly turn into a different configuration without an energy input. Which precise configurati...	[ "On the right side (from ionic to covalent) should be compounds with varying difference in electronegativity. The compounds with equal electronegativity, such as Cl (chlorine) are placed in the covalent corner , while the ionic corner has compounds with large electronegativity difference, such as NaCl (table salt)....
Was Lenin Bisexual?	I don't think it's a taboo, in theory something like that could be researched and discussed but it'd be a hot topic nonetheless. Anyway, these letters are absolutely fake. You don't have to be a historian to get that; if Russian is your first language, it's obvious. Writing style, rising level of craziness and so on. ...	[ "Despite his revolutionary politics, Lenin disliked revolutionary experimentation in literature and the arts, for instance expressing his dislike of expressionism, futurism, and cubism, and conversely favouring realism and Russian classic literature. Lenin also had a conservative attitude towards sex and marriage. ...
How much stomach acid is there in the average human stomach?	According to this reference: _URL_0_ In healthy individual who is fasting, gastric fluid (including stomach acid) is produced and emptied at a rate of ~1 mL/min, with an average of around 10 mL of fluid in the otherwise empty stomach at any given time. But this would obviously change depending on eating habits and be...	[ "A typical adult human stomach will secrete about 1.5 liters of gastric acid daily. Gastric acid secretion happens in several steps. Chloride and hydrogen ions are secreted separately from the cytoplasm of parietal cells and mixed in the canaliculi. Gastric acid is then secreted into the lumen of the gastric gland ...
Is the human blood stream an anaerobic environment?	No. You are correct to assume that oxygen is bound to hemoglobin, but oxygen is also [dissolved](_URL_0_) in the plasma, albeit at a much lower concentration compared to that which is bound to Hb.	[ "\"A. hydrophila\" is not as pathogenic to humans as it is to fish and amphibians. One of the diseases it can cause in humans, gastroenteritis, occurs mostly in young children and people who have compromised immune systems or growth problems. This bacterium is linked to two types of gastroenteritis. The first type ...
What other vehicles, other than aircraft, were used on carriers during WW2?	What vehicles might you be thinking of? A very small number of primitive helicopters entered service in the last year of the war, but most were operated by the Coast Guard and none were used aboard the major fleet and light carriers of the US Navy.	[ "Because the military effectiveness of aircraft carriers was then unknown, early ships were typically equipped with cruiser-calibre guns to aid in their defense if surprised by enemy warships. These guns were generally removed in World War II and replaced with anti-aircraft guns, as carrier doctrine developed the \...
why is weird al yankovic so widely popular and enjoyed?	He sold his soul to the devil, that's why. No other explanation. He's a nerdy white guy that plays an accordion. Nowhere would that make anyone popular.	[ "In Cary, David Menconi (\"The News & Observer\") stated Yankovic makes being funny look easy. He says: \"People still turn out for Yankovic because he's incredibly skilled at crafting cultural time-capsules starring himself. He's also about the last word in appealing adolescent silliness; my 16-year-old son came a...
how sore should i be after working out?	In short, you should normally be sore after working out, kind of like a deep feeling inside the muscle that is a little tender to the touch and aches a little when you use it, but it should not be in constant pain nor be really painful under any circumstances necessitated from normal use. When you're sore from working ...	[ "The soreness is felt most strongly 24 to 72 hours after the exercise. It is thought to be caused by eccentric (lengthening) exercise, which causes small-scale damage (microtrauma) to the muscle fibers. After such exercise, the muscle adapts rapidly to prevent muscle damage, and thereby soreness, if the exercise is...

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