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37413b
|
What was the most important battle for the Polish Army in the East during the second world war?
|
Everyone knows about how the Polish Home Army carried out the Warsaw Uprising and how the Polish Army in the West were the first to captured Monte Cassino. What about the Polish Army in the East?
|
AskHistorians
|
http://www.reddit.com/r/AskHistorians/comments/37413b/what_was_the_most_important_battle_for_the_polish/
|
{
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"text": [
"During the Battle of Berlin, German 17th Army and 4th Panzer Army attacked the southern flank of 1st Ukrainian Front, trying to break through to Berlin. At the Battle of Bautzen, between April 21st and 30th 1945, Polish 2nd Army held the Germans off with the aide of Red Army forces. It was probably the bloodiest battle the Polish Army in the East fought, and is something of a controversial event in Polish historiography of the war (esp. since the end of the Cold War)."
]
}
|
[] |
[] |
[
[]
] |
|
96rics
|
In Monty Python and the Holy Grail, a village tried a witch by seeing if she would float or sink when thrown into water. Did this sort of thing actually happen?
|
If the float or sink trial is just a comedic flourish, were there other ways of determining innocence that would end in death? Would the community care for the children of the executed, or in any way express remorse that they got it wrong?
|
AskHistorians
|
https://www.reddit.com/r/AskHistorians/comments/96rics/in_monty_python_and_the_holy_grail_a_village/
|
{
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"text": [
"There is always more to write, but in the meantime here is an answer I wrote that discusses how \"trials by water\" were used in Medieval England:\n\n_URL_0_"
]
}
|
[] |
[] |
[
[
"https://www.reddit.com/r/AskHistorians/comments/8v3u1w/comment/e1kj7eq"
]
] |
|
hchrw
|
Do we know what the Earth was like prior to the asteroid collision that formed the Moon? Could complex life have lived here?
|
I've read the Earth was still molten, but I don't know if that's the popular consensus or more of a guess. I was wondering how likely it would have been for complex life to have lived here pre-Moon before getting being wiped out by the asteroid.
|
askscience
|
http://www.reddit.com/r/askscience/comments/hchrw/do_we_know_what_the_earth_was_like_prior_to_the/
|
{
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"text": [
"It's highly unlikely that there was life. The collision happed several hundred million years after the solar system formed. The Earth, at that point, couldn't have supported life.\n\nAlso it wasn't an asteroid that hit the Earth, it was a planet the size of Mars."
]
}
|
[] |
[] |
[
[]
] |
|
2n0xvp
|
What gives humans ambition and how would you go about tricking your brain into being more ambitious?
|
Just always wondered what was it that really made a human ambitious and how to trick yourself into being more so im a pretty lazy person so yeah, :D just curious
|
askscience
|
http://www.reddit.com/r/askscience/comments/2n0xvp/what_gives_humans_ambition_and_how_would_you_go/
|
{
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"cmesdqx"
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"text": [
"Both genetic and environmental factors affect your ambition/laziness.\n_URL_1_ Science of Laziness\n_URL_0_ Science of Productivity\n\nThe best way to trick yourself into being more ambitious or stop being lazy, think about your future self. There was a research I recently read (sorry, can't find the source) that emphasized lazy people's brains' choose short term goals to long term goals. \n\nEvery time you are feeling lazy, try to think about your future self. And also, our brains work in a way that when you start a project, you feel inclined to complete it. For example if you need to write a 100 page paper, trick yourself by saying \"I will just write one page today\" and after you start it, chances are you will write way more than one page."
]
}
|
[] |
[] |
[
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"http://www.youtube.com/watch?v=lHfjvYzr-3g",
"http://www.youtube.com/watch?v=gd7wAithl7I"
]
] |
|
3kr2ky
|
what happens to cause places to become abandoned, and why are so many belongings left behind?
|
It's eerie seeing abandoned buildings, but even creepier when stuff is just left behind. What causes this?
|
explainlikeimfive
|
https://www.reddit.com/r/explainlikeimfive/comments/3kr2ky/eli5_what_happens_to_cause_places_to_become/
|
{
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"text": [
"A building becomes abandoned typically because the people there did not pay. \nThey might not be able to pay a bank for their loan, so the bank foreclosed it. \nThey might not be able to pay for the things they would do inside the building, or they decided it would save money not to pay for the things they would do inside the building and instead do it somewhere else. \n \nNow you have to pay people to move things. If that thing is very large you have to pay alot of money. So when they move out, they might pay people to move the expensive things that are small. If they had something like a very old machine or furniture, nobody would want to buy it and it might be cheaper and better to buy a new one. \nSo rather than waste money paying someone to move it, they just leave it there."
]
}
|
[] |
[] |
[
[]
] |
|
jab4i
|
can someone explain sister cities to me li5?
|
explainlikeimfive
|
http://www.reddit.com/r/explainlikeimfive/comments/jab4i/can_someone_explain_sister_cities_to_me_li5/
|
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"text": [
"When two cities are about the same size, have the same factories, or have mountains and rivers like each other. They form a partnership and agree to be friends. They usually exchange gifts like statues or art. Then, people from each city visit each other and see how they do things in their city. ",
"When two cities are about the same size, have the same factories, or have mountains and rivers like each other. They form a partnership and agree to be friends. They usually exchange gifts like statues or art. Then, people from each city visit each other and see how they do things in their city. "
]
}
|
[] |
[] |
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[],
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3wkct6
|
How long would it take the moon before it reached Earth in a direct course?
|
I just had a thought: if the moon suddenly changed course, directly towards Earth, how much time would it take before it entered the earth atmosphere? And how long would it take before it was all in the Earths atmosphere?
|
askscience
|
https://www.reddit.com/r/askscience/comments/3wkct6/how_long_would_it_take_the_moon_before_it_reached/
|
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"text": [
"The Moon's tangental speed is about 2,100 miles per hour. If all of that were used to approach the Earth, it'd take the Moon about 4 days and a half days to reach the Earth. The time limit in [The Legend of Zelda: Majora's Mask](_URL_0_) was pretty accurate."
]
}
|
[] |
[] |
[
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"https://i.ytimg.com/vi/JsOPHyuAuT0/hqdefault.jpg"
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|
3fakaf
|
AskScience AMA Series: We are three math experts here to tell you about our projects and answer your questions. Ask Us Anything!
|
We are three math panelists working on a variety of things. Our projects are listed below, along with when we'll be around, so ask us anything!
-----
/u/dogdiarrhea (11-13 EDT, 15-17 UTC) - I'm a master's student working in analysis of PDE and dynamical systems possessing a "Hamiltonian structure". What does that mean? Dynamical systems means we are looking at stuff that evolves with respect to a parameter (think an object moving with respect to time). PDE means that the thing we are describing is changing with respect to more than just 1 parameter. Maybe it is a fluid flow and we also want to look at how certain properties change with respect to their position and their speed or momentum as well. Hamiltonian structure is a special thing in math, but it has a nice physical interpretation, we have a concept of 'energy' and energy is conserved.
-----
/u/TheBB - (12 EDT, 16 UTC) - I did my undergraduate education at NTNU in Trondheim, Norway (industrial mathematics) and my Ph.D from 2009 to 2013 at ETH in Zurich, Switzerland, on function spaces for the discretization of kinetic transport equations. For the last year I've been working at a private research institution in Trondheim, where we do simulation work. The most significant recent project I've been working on is the [FSI-WT](_URL_0_), where we've been doing fluid-structure interaction (FSI) simulations on wind turbine blades.
-----
/u/zelmerszoetrop (15-17 EDT, 19-21 UTC) - I studied general relativity/differential geometry in undergrad and start of grad, switched to number theory in graduate school (dramatic turnaround!), and then did a second dramatic pivot by going into data science when I left academia. A current project I'm working on involves reconstructing a graph (as in, a set of nodes and connections between them) with deleted edges after training on other, similar graphs (with the right definition of "similar").
|
askscience
|
http://www.reddit.com/r/askscience/comments/3fakaf/askscience_ama_series_we_are_three_math_experts/
|
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"Have any of you ever hit a block where you didn't think math was for? Until this semester I was an adult math student (I already have one b.s. but had to start over) and then I hit calculus 1... and got owned and dropped after thinking about it all summer long. My thinking was if calc 1 was as rough as it is my future success wasn't too likely",
"Every mathematician I come across always has his/her favourite equation. The most beautiful one they've ever come across. I'd like to ask each of you which piece of maths, that you've come across do you find the most beautiful? \n\nThe one that still makes you stop and think 'wow'?",
"\n\nA question for /u/zelmerszoetrop , in particular.\nHow did you background at undergrad/grad level affect your current work. Did you have to go through relearning in the data science sector? \nHow can ideas in pure math (related to your background) be applied to machine learning type questions?\n\nIs it possible to work on such problems while remaining in academia? \n\n",
"Can anyone give me some geometric intuition regarding integrable systems, and their relation to symplectic forms? I vaguely remember something about sympleticity in two dimensions being related to area preservation, so I imagine that would let you rule out a lot of pathological behaviours.",
"First of all, thank you for doing this AMA.\n\nMy question might be a little philosophical or subjective, but... in your humble opinion, how does one get better or improve at math? I'm in finance and accounting, so the very highest levels of mathematics are definitely _not_ around, and I've already finished most of my math courses anyway, but I feel like I lack problem solving. Like, quick example, I have had a hard time finding the required patterns in programming and coding for solving something, even though I think I understood the concept of the commands; or, another example, thinking in 3D (as in, a x,y,z coordinate system or objects, like polyhedrons) is something I have always struggled with. So long story short, I have decent grades and never really had a hard time with maths, but I honestly feel like I am bad at thinking; as in, mathematically.\n\nOr does it simply come down to the fact that in the deepest depths of my brain, I'm more of a humanities / social sciences guy than a formal sciences one?\n\nSorry for the length of my post, I did not mean to monopolize your time, and am looking forward to your reply.\n\n\n\n",
"Why does .99999 repeating equal one?",
"Once, during my MS days, I studied nonlinear systems (Khalil was my text book). I missed those good days. Now I am far deep into another field, but I remember all the fun stuff my professor used to explain. \n\nOne thing that stood out was the predator-prey cycles. I remember studying the stability equations of predator-prey species with their growth and death rates described by nonlinear time varying equations.\n\nCould you throw light on that as applied to us humans and our resources. I always felt that this insight had much larger applications.",
"Do any of you have any familiarity with mathematical approaches to language? If so, do you have a sense of what the area of language can tell us about math or vice versa?",
"How would you fix math education in the US?",
"Without use of a calculator, which is bigger: e to the pi, or pi to the e?",
"Thanks for the AMA! \nSo I come from a history of a BS in mechanical engineering and a masters of computer science. My current job has been pushing me into what I believe would be traditionally deemed a Data Scientist for big data. \n\nDo any of you have any suggestions for someone who is new into data science, of areas or things to focus on to be better or more competent in the area? ",
"I'm curious how you all use computers in your work, given that many of the calculations and what not that you make are probably quite complex. While I'm sure there are programs out there designed for high-level mathematics, I'm curious to know if you ever write your own and if so, what programming language(s) do you use?\n\nThanks for answering these questions and sharing your work with us!",
"For each of you, how did you end up studying (what seems to me) a random/arbitrary topic? What applications/enjoyment do you get out of it?\n\nFor those who've had experience with both, what are the most drastic differences between academia and industry specifically in the field of mathematics?\n\nCheers!",
"One of the millennium prizes is to make progress in solutions and characteristics of the Navier-Stokes equation. Do you know of any progress on that front? \n\nAlso, do you guys have a favorite unsolved problem in math?",
"Thank you for doing this AMA! \nI'm an engineer and tutor math on the side... I often find my high school, and younger, students a bit... underwhelmed... in other fields like art, literature, and physical sciences I can point to accessible Master-works and say, \"This is beautiful. This is *art*\". \n But with math, I have trouble. I guess because of the level of understanding needed to \"get\" why the math is interesting. \nAny suggestions, or examples, that may be helpful? \nThank you. ",
" I work in a Biomolecular research lab and they want me to develope a fractal model for ion channel kinetics and was wondering if you had any sugestions for books or papers that I could read that would be a good starting point. \nI was also wondering if you have any advice for someone who would like to get into Biomathematics. ",
"* How would you explain infinity in words ?\n* What's up with the sum of all positive integers being -12 ? (numberphile did a video on it)",
"My question is primarily for /u/dogdiarrhea.\n\nI'm currently studying control engineering, so naturally I deal with dynamical systems and differential equations quite a lot. Most of my courses treat the subject from an engineering standpoint, i.e. mostly focused on the tools necessary for practical work. I do, however, really enjoy the more rigorous and theoretical side of mathematics, and have taken a few courses aimed primarily at mathematicians on the side.\n\nOnto my question: Is there any part of your field (or mathematics in general, outside of what I get from what you'd encounter in a typical control engineering / robotics education) that you believe I would benefit from studying? I realize there might be a temptation to say \"all of it\", but given limited time and resources, is there anything you believe stands out?\n\nIf anyone else have any suggestions I'd love to hear those as well! I just though /u/dogdiarrhea was in the field most appropriate for my situation.\n\nOh, and shout-out to /u/TheBB. NTNU represent!",
"I'm a grade six teacher and am wondering, as math experts, what do you think are the most important things to teach kids that age?\n\nBasic math facts? Problem solving? Basic Algebra? \n",
"I realize what Pi is and what ratio it represents... but if we know X digits of Pi.. how does one figure the x+1 digit.. x+2 digit.. so on and so forth ?",
"I want to be an engineer and have to take the calculus and physics battery. I took physics 1 and 2 in high school and recently dropped out of engineering school because of money.\n\nWhile I build my funds up to go back, what should I be studying (intensely no doubt) to make calculus and physics less of a strain to learn and, most importantly, master.",
"At /u/dogdiarrhea: I have a copy of [this book](_URL_0_) in front of me. How weird is it that for discrete point vortices, the x and y coordinates are canonically conjugate to each other?\n\nAt /u/zelmerszoetrop: Consider the [\"Big Omega\"](_URL_2_) prime counting function Omega(n). Prove that 3*2^(n-1) is the only value of m in the range 2^n < m < 2^(n+1) such that Omega(m) = n.\n\nETA: Also at /u/dogdiarrhea: *Is* there a Hamiltonian formulation of the full set of Navier-Stokes equations? Of course we have the [1950 Irving/Kirkwood paper](_URL_1_) which extracts (as an approximation) NS from the entirely Hamiltonian molecular dynamics which underly it. However, whereas MD *is* Hamiltonian, NS is dissipative... ",
"Hi! Thanks for doing this AMA! As someone about to start my second year in undergrad and trying to pick between math, stats, or a science like chemistry or physics for a major what made you choose to keep studying math? Is there one specific aspect of the field that really appealed to you? I've taken up to differential equations (a class which I didn't find that interesting and made me really wonder if I wanted to keep doing it :/)",
"Was Math invented or discovered?",
"What are your thoughts on /r/theydidthemath?\n\nHave you ever poked your head into a thread, looked at a [Request] post, read the \"best\" answer, and just shook your head at how wrong they were? Or impressed at how bang on the user got it?",
"/u/zelmerszoetrop I have an additional question for you—it is a bit nebulous and I hope the context isn't inappropriate. I'm currently dealing with a bit of research where I am given 4 different objects (each with various properties) and based on their properties, I have to figure out which 2 pairs go together. Are there any branches of mathematics you familiar with that can help me make rational choices to pick out which pairs most likely go together? \n\nBasically the type of framework which would allow me to evaluate which two pairs AB, AC, AD, BC, BD, CD are most likely to be correct. I'm not looking for you to do my work for me, but maybe a finger pointing at X sub field would be immensely helpful.",
"For any/all of you, what are some of your favorite motivating problems for different areas of math?\n\nRecently I've wanted to learn algebraic geometry. It's interesting but tough, but I feel like I need motivation. A lot of the \"big results\" seem so abstract it's hard to look at them and want to know how they're solved. So what are some simple to understand results that motivate cutting edge areas of mathematics?",
"OP's, thank you for doing this AMA.\n\nI'm a 3rd grade teacher (US) and am always striving to inspire my students to be passionate about whatever interests them. As people who obviously developed a keen interest in and appreciation of mathematics, can you recall any particular experience you had in which a certain assignment, activity, etc inspired in you a greater interest in math?",
"Hello, question for /r/dogdiarrhea or anyone really. How do you build a better model? What are your opinions of blackbox optimization algorithms? I am studying to become an actuary, and when reading criticism of the Black Scholes model (That it assumed no discontinuities in the paths, geometric brownian motion - in order to give it finite variance along with other items), it was proved that stocks really do not follow geometric brownian motion and that the variance is infinite- (Mandlebrot) thus BlackScholes does not hold. I guess my question is how do you build a better model, and are some things impossible to model effectively? ",
"Question for /u/dogdiarrhea - what techniques in mathematics and mechanics would you recommend for a mechanical engineering student that most students don't use or just aren't taught to engineering students? \n\ne.g. things like Lagrangians\n\nEDIT: Question for all: what are good books for an intro to solving PDEs and Laplace Transforms that an engineering student can use and why are they good? (Note - I'm the type of guy that doesn't like just being told what to do by a maths book - I like knowing why it works. My other friends in engineering get annoyed when I ask for proofs.)\n\nThanks for doing this AMA!"
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6nes3d
|
In the past? How did societies define and delimit 'countries' or 'states'?
|
Please bear with me as I'm actually having a hard time wording my question, such is my ignorance and ill-equippedness in the subject.
So as I understand, the concept of the 'state' (i.e. what we colloquially call a 'country') really came into its own after the Peace of Westphalia. Before that, territorial boundaries were not really respected by rival monarchs, and so no true concept of a sovereign state existed.
Then the idea of 'nation-states' came along, wherein states where defined and empowered by the nation (i.e. the people, or ethnoliguistic group) that were its population. Not quite sure about the boundary there (i.e. when is a state not a 'nation' state?)
So I'm trying to figure out what came before.
Before the concept of states, how did people really organize the world?
From how I understand it, there was the concept of 'realms', i.e. areas wherein a magnate or monarch held power (god-mandated sovereignty).
But was a realm defined as the entire territory (and all the resources within, such as the population) ruled by a monarch? Or was there still nationhood built into it, and therefore a realm gained its own identity on its own?
I ask because I've recently been reading up on Phillip II. Now, over the course of his life, from birth onwards, he accrued multiple titles such as King of multiple 'states'. He was King of Spain, King of Portugal, King of Naples and Sicily, King of England and Ireland*, Duke of Milan and lord of the Seventeen Provinces of the Netherlands.
How did that work? Were all of those territories considered a single, aggregate 'realm'? I.e. a single territory under his rule? If so, what was the word and concept used to define 'Spain', 'Portugal', etc.?
If each those were considered realms (i.e. kingdoms) in their own right, then how was each kingdom defined? If they were defined as 'the territory ruled by a king', then wouldn't they be 'assimilated' into the larger 'realm' of 'Phillip's State'?
Or am I approaching this wrong, and kingdoms/realms/states were *not* defined by who ruled them, but by some other metric or set of rules? That England was a state/kingdom, and acknowledged as such, whether it was ruled by its own King, or was just part of a laundry-list of kingdoms ruled a dynasty? That the territory and its people was a concept that stood inalienable (i.e. similar to a nation), and had its own identity so difficult to extinguish that a dynast didn't just absorb the territory into his realm, but considered it another realm that he ruled in a separate capacity?
Basically, I'm just trying to wrap my head around how society was divided in the past. If it was a top-down system or a bottom-up system of defining each 'territory'.
Any learned input would be appreciated.
|
AskHistorians
|
https://www.reddit.com/r/AskHistorians/comments/6nes3d/in_the_past_how_did_societies_define_and_delimit/
|
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"Not a historian but have studied political science so will try to give brief input based on that. \n\nYes the nation-state concept was an experimental Enlightenment ideal, under which international relations continue to be organized to this day, although it is increasingly under strain and may not survive or may evolve into something new. \n\nBefore the nation state ideal, a territory may have had certain unifying ethnic characteristics, but those were not considered necessary to governance or rule, other than practical considerations of language, taxation, religion, and such. \n\nInherent in the nation state concept is the idea that the government takes it's legitimacy from the consent of the nation (the people). Prior to the concept, the consent of the people was not considered necessary for the legitimacy of the government. That feels a bit astounding today but cannot be overstated. \n\nA foreign ruler may have chosen to honor historical practices in a region that comes under his control. Or he may just as well not. Depending on his motives and goals, he may leave a region largely alone except to collect taxes, or he may become extremely involved in language, church governance, birth and death rolls, administration, military draft, education, and the courts. \n\nConsider England after William the Conqueror in 1099. He came in and swept the slate clean, instituting new regimes in all those areas and then some, especially language, real estate, and the courts. This was difficult for several hundred years but over time, the language, customs, and legal practices metabolized the new protocols. \n\nYou hardly ever hear of or consider England as being 'under colonization by the French' in that time period. Partly because the culture and legal practices metabolized, but also because the idea of 'colonization' is one of nation-state and empire, which was not the ideological framework of the people of the time. \n\nToday, the nation state ideal is under strain by 'non state actors.' Which sounds like some weird, fancy government speak except it actually has meaning. \n\nThe nation-state ideal holds that a nation should be a self-determing group of people who voluntarily give their consent to form a state, and the state then holds a monopoly on violence. Conversely a state is formed of a self-determining nation. But what happens when you have a self-determining nation (ex: ISIS, the Palestinians, the Kurds) *without a state*? And further what happens if these stateless nations have power via military influence or force? They undermine the very framework of *state* monopoly on violence, and therefore the stability of international order as a whole. \n\nHistorically stateless nations were like the Jewish people, pre-Israel, or like Gypsy/Travelers today, or even like Native Americans/First Nations in the US and Canada. They could be satisfied or dissatisfied with their lot under the rule of other regimes, but they did not have recourse to organized military violence. Only the states had the capital and the wherewithal to produce organized violence. Stateless nations certainly existed, and may have been put down or kept down, but by and large they were not an objective threat to the facts on the ground of day to day governance. \n\nToday, these non-state actors have power the nation-state framework literally is not organized to deal with. It's not 'international terrorism' that is the problem. It is the power of stateless nations to wage war on states, leaving states with almost no recourse to reach them. \n\nHence, the now global, never ending 'war on terror.' It is an *existential* war being fought at the root level of the ideological framework organizing the world itself. \n\nIt is akin to the violent reorganization Europe went thru in the Reformation and for hundreds of years after, wherein Catholics were under suspicion of being what today we would call international terrorists, because they were believed to answer to the Vatican and not to their local governments. That took several hundred years and great loss of life to play out, and only finally resolved when State was separated from Church - when the ideological framework itself changed. The ancient and dying framework of Holy Roman Empire gave it's last gasps and finally expired. Separation of church and state is taken for granted today (in the west). \n\nWhat the new answers or solutions will look like in the current and coming upheavals remains to be seen, but the international nation-state framework itself will be changed in some core existential way, if it survives at all."
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[] |
[
[]
] |
|
2lk8tw
|
In quantum mechanics, what exactly counts as observing?
|
Say we have an electron. It's position is a wave of probability until it is "observed", at which point the wave of probability collapses into a single point. My question is: what exactly counts as observing?
|
askscience
|
http://www.reddit.com/r/askscience/comments/2lk8tw/in_quantum_mechanics_what_exactly_counts_as/
|
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"We don't know. Quantum mechanics itself doesn't answer this question, and it's left up to debate. You might find [this page](_URL_2_) on interpretations of QM interesting.\n\nI'm partial to the [objective collapse theories](_URL_0_), probably because I heard Penrose himself explain his view, in person. He holds that an ‘observation’ happens when, informally, the difference between possible outcomes becomes large enough.\n\nOther relevant articles are the [Copenhagen interpretation](_URL_3_) (which is perhaps the one most commonly accepted) and the [many worlds interpretation](_URL_1_), which you've probably heard about before.",
"I've never heard a satisfactory answer to this question. \n\nI can list some things that definitely DO count as observing, but I wouldn't try to define observation. I don't think anyone knows for sure.",
"I see people jumping into the fray of measurement in QM, while philosophically muddy, let's take a step back at look at what observation actually does, here we're on more firm footing: Observation, or the act of measurement is to get a single value or answer which has surpressed any resulting entanglement.\n\nI'm not fond of approaches which say *this* is quantum, but *that* is classical--So inherently, entanglement has to occur to some capacity, but in a way that you get redundancy which overwhelmingly biases the probability to a single value, otherwise you can't reproduce classical physics which is always single valued.",
"It has been understood and generally accepted for a few decades now that an \"observation\" or \"measurement\" in QM occurs whenever the macroscopic state of the measurement apparatus becomes entangled with the state of the system under study. In practice what this means is that observation occurs whenever the the measurement apparatus interacts with the system under study through any interaction that is strong enough to cause some bit to flip or a needle to move. So, for example, if you completely isolate your electron in a vacuum chamber, no measurement occurs until, for example, a photon from the electron escapes into the walls of the vacuum chamber. Then the electron's wave function \"collapses\" because it has become entangled with the vacuum chamber, which in turn is entangled with the measurement apparatus, so that any bit that flips or needle that moves in the measurement apparatus is correlated with whether the electron was at point X or Y, for example. ",
"Whatever else it is, an observation always has to consist of an interaction with another quantum system (because that's all there is in the universe). So an observation will never really reduce the position of the electron to a _point_, because the observing quantum system doesn't have that specificity either. It will simply narrow the probability distribution. For instance, a photon with a wavelength of 100 nm will narrow the electron position down to around a 100 nm range. The assumption of a classical observer who can nail down exact positions is a handy approximation for intro quantum mechanics, but it breaks down once you start asking questions, as you have seen. \n\nThis makes other types of observations clearer as well. For instance, why doesn't Earth's gravity acting on an electron count as an observation? Well, in some sense it does count, but the interaction reduces the possible locations for the electron so little that it gives almost no information. Whereas laboratory experiments are specifically designed to get specific information, thus narrowing the probability distribution a lot - so normally people focus on these and call them \"observations.\" ",
"All the other answers do a very good job of explaining, but this bears repeating for clarity:\n\nWhen you read \"observed\" in this topic (or ever with regard to quantum mechanics) remember we mean it in the physics sense of \"interacts with something else\" **not** \"a consciousness or being observes\" in the philosophical/plain language sense.",
"There are so many misconceptions about this, including in the responses here! Before explaining, I need to provide an important disclaimer about this question.\n\n*\"What is observing?\"* is not a strictly scientific question. Other examples of this type of question are the philosophical discussion of material substance, or the philosophical discussion of whether or not scientific empiricism is \"true\". All of these questions are asking about how to interpret a scientific result. This means that that the answer is at least partially a philosophical one and as a consequence is, at least partially, unproveable. But that doesn't mean we can't distinguish between good and bad interpretations! Typically we argue that a *good* interpretation is one that satisfies Occam's Razor. One that doesn't inherently hold contradictions, and one that is simple compared to others.\n\nNow that we know the stakes, let me try to explain the results, and how I've come to interpret them. I think the proper way to address the issue is to begin by explaining some poor choices of vernacular behind this section of physics.\n\nFor starters, quantum mechanics and classical mechanics are not competing descriptions of the universe, they are simply poorly named categorizations. Better names would be classical phenomena and quantum phenomena; this frames their competitiveness (or lack-there-of) more appropriately. \n\nSecond, observation is not terribly important, and a much better phrase for understanding the quantum phenomenon of probabilistic states is with the phrase **information isolation**. A great textbook that takes this perspective and is a very enlightening read is [**Benjamin Schumacher**](_URL_0_)'s [**Quantum Processes Systems, and Information**](_URL_1_).\n\n**Ok, we get it it, so what's this other interpretation?**\n\nInformation isolation is a property that a system can have. An excellent example of this is the Schrodinger's Cat experiment. The system (decaying atom, poison, cat, scientist) is constructed in such a way that the scientist is informationally isolated from the other components in the system. Until the scientist interacts with the other components of the system and BREAKS this information isolation -- which may or may not result in their reading/interpretting the results, the state inside the box is unknown. \n\nLet's be clear then: state collapse is not a universal event, it is an event relative to the informationally isolated component (scientist in this case) from the other informationally-correlated components (decaying atom, poison, cat). This particular collapse occurs when the scientist's observable universe contains the information required to deduce what happened inside the box. What happened inside the box is still a fixed thing, regardless of when that information isolation is broken, at least as far as the informationally-correlated components are concerned.\n\nMany of you might be asking, *\"NuneShelping, this doesn't seem weird at all, it just seems obvious.\"* and you're right, it is. Don't give in to the hype/mysticism that ignorance has created in this subject. Also, read the book I suggested, it's good.\n"
]
}
|
[] |
[] |
[
[
"http://en.wikipedia.org/wiki/Objective_collapse_theory",
"http://en.wikipedia.org/wiki/Many-worlds_interpretation",
"http://en.wikipedia.org/wiki/Interpretations_of_quantum_mechanics",
"http://en.wikipedia.org/wiki/Copenhagen_interpretation"
],
[],
[],
[],
[],
[],
[
"https://en.wikipedia.org/wiki/Benjamin_Schumacher",
"http://www.amazon.com/Quantum-Processes-Information-Benjamin-Schumacher/dp/052187534X/ref=sr_1_10?s=books&ie=UTF8&qid=1415385596&sr=1-10&keywords=quantum+information"
]
] |
|
fpuvra
|
How do false positives happen in Viral testing?
|
That might be quite an open question. As I understand it, testing involves changing the RNA in the sample to DNA and then matching it to another sample. That seems kind of foolproof, so why do people test positive for a virus they don't have?
|
askscience
|
https://www.reddit.com/r/askscience/comments/fpuvra/how_do_false_positives_happen_in_viral_testing/
|
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"It can sometimes be harder to create an accurate PCR based test than it would seem. We try to design primers and probes that will not match up to anything other than the sequence of interest, but that isn't always possible. Even when using NCBI Blast to check for similar sequences, we don't really know if any unspecific amplification will occur until we test many samples. Unspecific amplification is when we are amplifying what we think are the nucleic acid sequences of interest, but we are actually looking at some other amplicon. One source of this could be from contamination of another organism. \n\nEvery part of PCR has error and noise associated with it. We must also draw some threshold at which a call is declared positive vs negative. If the threshold is drawn low, issues with the instrument's optical reader may artificially declare a positive if the signal spikes. This is just one of infinite things that can go wrong. Of course we try to avoid false positives by doing things like amplifying different regions of a virus and choosing appropriate thresholds, but some false positives will slip thru. In the case of this pandemic, a FP is much better than a FN. That means that we want a very sensitive assay, even if that means compromising some specificity (high sensitivity means almost all positives will be called positives, but some negatives might as well)."
]
}
|
[] |
[] |
[
[]
] |
|
7v1t92
|
When did fist fighting (as opposed to dueling or brawling) become a socially acceptable way for 19th-20th century western men and boys to settle problems? And how did it fall from favor?
|
As to the first part, I seem to recall reading that bare-knuckled boxing emerged in the 19th century as a way for gentlemen to settle disputes without the danger of a duel with sword or pistol. Is this right? And as the second, I get the impression that it remained culturally acceptable in the west for two men to engage in a "fair fight" until fairly recently: say, the last thirty or forty years. When did this begin to change and why?
|
AskHistorians
|
https://www.reddit.com/r/AskHistorians/comments/7v1t92/when_did_fist_fighting_as_opposed_to_dueling_or/
|
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"Boxing does become incredibly popular as a 'gentleman's sport' from the late 18th century, reaching its fashionable peak between c.1810-30. That said, it was still largely regarded as a spectator sport, with working class men doing most of the actual fighting. Pierce Egan, an Irish sportswriter living in London, wrote a popular series of articles which were printed in several volumes between 1813 and 1829 as *Boxiana: or, the science of pugilism ancient and modern*, which consolidated the status of boxing as a fashionable sport. You can see a representation of an 1820s boxing match [here](_URL_0_), taken from Egan's other major publication, *Life in London*.\n\nThat said, I haven't come across any accounts of elite men settling their personal disputes by way of a boxing bout. It may well have been done among boys - William Thackeray, writing in the 1840s but looking back to the 1800s-1810s, put a fistfight between gentleman schoolboys (Dobbin and George) into the plot of his novel *Vanity Fair*."
]
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|
[] |
[] |
[
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"https://www.gettyimages.co.uk/detail/news-photo/tom-jerry-and-logic-backing-tommy-the-sweep-at-the-royal-news-photo/113632041#tom-jerry-and-logic-backing-tommy-the-sweep-at-the-royal-cockpit-the-picture-id113632041"
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|
6q7avl
|
why does car ignition work as it does? (instead of having a button)
|
Why does car ignition work as it does? (I mean why do you need to turn key and hold it to start the car) instead of just having a button - > Press once and it automatically starts the engine.
I know many newer cars have buttons but even in those cases - you need to hold the button until car starts up.
What makes ignition system requiring constant input rather than just one-time trigger/input?
Not sure about flair: Engineering or Technology, setting Engineering as there is more engineering in cars than technology.
|
explainlikeimfive
|
https://www.reddit.com/r/explainlikeimfive/comments/6q7avl/eli5_why_does_car_ignition_work_as_it_does/
|
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"Newer buttons you just need to press quickly, I have a new Honda and that's just a quick push not a hold\n\nOlder keyed ignitions when you turned them from ON to START you were triggering a relay which connected power to the starter motor. If you remove the key from the start position then the relay turns off and the starter loses power so you have to hold it there until the car starts\n\nIt was only relatively recently that tech moved to a point where we're comfortable with keyless ignition. To do keyless ignition you need a good way to detect the key is in the car and that it is the right key, this is needed for theft prevention and so unattended children don't start the car and roll away. To do a quick push button ignition requires more synchronization between the starter circuit and the ECU, more things going on means more hardware means more $$$ for something that people aren't necessarily willing to pay more for. You also need to overcome the hundred years of inertia of holding the key/button in the start position until the car starts."
]
}
|
[] |
[] |
[
[]
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|
26j9p5
|
what exactly are ukips (uk independence party) goals?
|
explainlikeimfive
|
http://www.reddit.com/r/explainlikeimfive/comments/26j9p5/eli5_what_exactly_are_ukips_uk_independence_party/
|
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"Well, the first thing to keep in mind is that all that's happened is they've got a small number of seats in the EU Parliament, nothing else.\n\nThey'll probably get a fair showing in the General Election next year sadly, but chances of them getting a majority are basically nil.\n\nTheir biggest policy to withdraw from the EU. \n\nThey want to institute a procedure for the public to call for a binding referendum on any issue.\n\nAs regards immigration, they aren't totally against it. They simply want strict controls. As an immigrant you'll have to have a paying job, pay taxes and support your family through education and healthcare without any Government assistance for 5 years. After that 5 years, you can get assistance.\n\nRestrict the NHS to UK citizens and long term residents. This means refusing care to immigrants and tourists unless they purchase health insurance.\n\nRemove income tax on the lowest earners.\n\nRemove the inheritance tax.\n\nReduce corporation tax.\n\nAbolish a scaled tax system, and introduce a flat rate of tax at 31%\n\nAbolish national insurance.\n\nProvide retraining to all those out of work.\n\nScrap so-called 'green' taxes, which are taxes on industry etc based on their carbon emissions.\n\nScrap subsidies of renewable energy projects.\n\nInvest in fracking.\n\nTake a strong anti man-made climate change stance. This would include prohibiting schools from including it in their teachings, and prevent local authorities spending public money on climate-change related efforts.\n\nSignificantly reduce foreign aid.\n\nReduce or remove 'good behaviour' reductions on prison sentences, also substantially reduce opportunities for parole.\n\nRestructure the NHS somewhat, to change access provisions and local governance. Including locally elected hospital boards, with responsibility for inspecting and overseeing hospitals.\n\nFocus social housing assistance on those with local routes, letting folk reliably stay in the same area as parents and grandparents.\n\nCut roughly £77bn in the public sector to pay for tax cuts.\n\nIncrease NHS subsidies for dental and optical treatments.\n\nOpposes same sex marriage.\n\n40% increase in defence spending, including the purchase of 3 new aircraft carriers. \n\nAnd thats basic outline, there are obviously other policies. Let me know if you've any questions, I'll try and break it down further :)\n\n"
]
}
|
[] |
[] |
[
[]
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||
2yuofe
|
how is it that birds can imitate the english language very well with beaks, while mammals of similar physical facial structures as humans (dogs, monkeys, etc) cannot?
|
Seems like it'd be way easier for an ape to speak than a parrot
|
explainlikeimfive
|
http://www.reddit.com/r/explainlikeimfive/comments/2yuofe/eli5_how_is_it_that_birds_can_imitate_the_english/
|
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"I too would like to know this answer. Also why can a parrot imitate a language with ease, but alot of people find it difficult?..... ",
"Basically, birds evolved to make lots of sounds and some birds evolved to mimic sounds. It has nothing to do with language or learning to speak. To see that, check out the lyre bird:\n\n_URL_1_\n\nWhen a parrot mimics speech, it does so because it has a well-developed syrinx and some tongue control that allows it to manipulate airflow and create a variety of sounds. They don't do it through vocal cords like we do; the fact that they mimic human speech is just a side-effect of their profound vocalization/mimic abilities. \n\nIn contrast, chimps and monkeys have very underdeveloped vocal tracts because they don't make very many sounds. See here for comparison (note the highlighted area):\n\n_URL_2_\n\nAnd a similar one for the dog: \n\n_URL_0_\n\nBecause they didn't evolve to vocalize much, except for a few grunts/barks, their vocal tracts are smaller, tongue movements less precise, and generally they are unable to manipulate airflow like we can. ",
"Dogs have facial structure similar to humans?",
"It's not the structures of our face. It's what's in our throats. Humans have very developed vocal cords compared to most other mammals. This is why we teach sign language to great apes instead of just teaching them a spoken language. Birds, on the other hand, are very strong vocal communicators, thus there are many birds that have the capacity to speak human languages.",
"I own a parrot. It's the tongue. They have crazy tongues!!!\n\nThey mostly do vowels anyways because they don't have lips. ",
"Well, some dogs can speak English. [Here's](_URL_0_) a video of a dog saying 'sausages' on 1970s UK television. It's not exactly at parrot-level English, but hey.",
"If orangutan's vocal chords are undeveloped, could it be possible to implant human chords in? I'm m no orangutan expert but they seem smart enough to understand language if they had the chance",
"To get to the short of it. Their voice boxes are in a different location. It's a weird anthropology thing. Our voice boxes are in a place that allows us to make all different types of sounds. This placement also makes it easier for us to choke on food or something else. Chimps on the other hand have voice boxes that are lower down and therefore can't make as many sounds but also it's harder for them to choke on something. So at some point in our evolution it became more important for us to talk to each other than to lower the risk of choking.",
"I entered here thinking the post would be about their ability to *specifically* emulate English language. Seeing as its not the case at all... What the hell. Wouldn't it have been more logical to jusk ask \"how comes birds can imitate our voice in a better way than mammals\"?",
"Consider speakers have no beaks at all yet they can reproduce with much higher fidelity. ",
"It may seem like birds have very different mouths than us, but when you consider that for most sounds we actually use the very back and top of our tongue rather than our lips, it's more understandable. This is why ventriloquists are a thing, for example. Birds have small flexible tongues and a lot of space to move them around in. Apes and dogs have big tongues and not very much space to move them around in. In fact, the human vocal box dropping (thus creating more room) is considered a possible impetus for the original development of spoken language.",
"My African grey parrot is about 6 years old.. He has learned to mimic Vietnamese phrases, the same noise when my grandpa coughs, he sounds like every bird that we have around here but the funniest thing is... He cant fly.\n\nI always let him out of the cage which is outside on the patio (or inside depending on season) and I tried to see if he would fly (don't ask why, curiosity got the best of me). Picked him up with my hand as usual and gave him a light toss. He glided for about 20-30 feet, losing altitude pretty quickly, freaked out and flew straight into the fence.\n\nIve never laughed so hard and didn't notice he walked back to me instead cause my eyes were blurry from all the tears ",
" > How is it that birds can imitate the english language\n\nHuman sounds, not just the English language.",
"Birds have alot more control control of their \"speech\" because their syrinx is designed to make a wide range of sounds. Other mammals, like chimps, have a higher larynx than us and dont have the same level of control over their breathing. They can only manage limited sounds, plus humans have a mutation that alllows speech formation in the brain.",
"Tell me more about how dogs faces are like humans...",
"What if someone were to surgically implant a well-developed voice box into an animal that doesn't speak as well as in comparison as humans?\nWould it be much too complicated, considering that the brain wouldn't be able to properly communicate with the new voice box?\n\nDisregard ethics and organ rejection, this is strictly hypothetical.",
"English language? My parrot speaks Spanish!",
"Your mom's facial structure is similar to dogs, monkeys, etc..."
]
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|
[] |
[] |
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"http://www.merckmanuals.com/media/pet/figures/DDD_dog_nose_and_throat.gif",
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"http://pubpages.unh.edu/~jel/images/vocal_tract_chimp.gif"
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31smdw
|
are solar roadways as effective as the video claims? why or why not?
|
I recently watched this video:
_URL_0_
It seems like a very promising technology, so why hasn't it been in production yet? What are the drawbacks to it?
|
explainlikeimfive
|
http://www.reddit.com/r/explainlikeimfive/comments/31smdw/eli5_are_solar_roadways_as_effective_as_the_video/
|
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"No. Solar panels are hard to make cost efficient if you point them towards the sun and nothing is blocking them.\n\nNow imagine that you put them flat not the ground ei not pointed at the sun and then put glass that is gonna be scratched up and dirty over it. You are hardly gonna get any power at all from the panels.\n\nThen then you have the problem of cost, glass and electronics are way more expensive than black top, which is mostly gravel.\n\nAlso making a road out of tiles is a terrible idea. As the load is unevenly distributed the tiles will act like a seesaw every time you drive over it and will eventually crack or come lose. And can you imagine the danger if even one tile comes lose?\n\nThen you got the LED lights. It you take a look at all the pictures they released of the lights you will see that they are taken at night and taken from above. But when you are driving along you are looking at the road at a shallow angle and in the full light of day there is no way you would see the lights.\n\nFurthermore, they claim they can heat the tiles to melt ice. Which it simply a stupid idea. Melting snow and ice will take an insane amount of energy, far more than you could possibly get from the solar panels. There is a reason why we use snowplows to just move the snow to the side of the road instead of using flamethrower cars to melt the snow off the road.\n\nTo summarize, almost every claim solar roadways make has no grounding in reality. It's simply a scam playing on people good intentions for green energy. There are far better alternatives than solar roadways.",
"Absolutely not. It's a complete scam and full of nonsense.\n\nSolar panels are great, but they're expensive. Paving roads with them would be *super* expensive.\n\nSolar panels work great when they're at a low latitude, but less so when they're at a higher latitude. The video spends time talking about putting them in places to melt snow. This is an awful place to deploy solar panels. For that matter, simple conservation of energy shows that the best way to melt snow with sunlight is to just absorb that energy as heat. This makes asphalt already be one of the best surfaces there is.\n\nThey make nonsense claims about using recycled material, but for a solar panel you want the clearest glass possible, not some recycled glass that's cloudy or just straight-up brown. Also, asphalt is already one of the most recycled materials on the planet.\n\nSolar panels work best when they can track the sun. Roads work best when they *aren't* moving. There's a clear conflict here.\n\nSolar panels work best with direct sunlight, not shade. Cars provide shade. So does all the road grime coming off of them, for that matter.\n\nRoad surfaces need to be durable and provide good traction. The video hand-waves that away, but seriously, there's a reason we don't pave roads in glass. Yes, we're all impressed that you slowly drove a forklift on the roadway, but that doesn't show a damn thing. Show a stress test of 100,000 cars driving over it at highway speeds and we'll see how clear they are then. Show a semi emergency braking and see how much traction it provides. Especially try this while wet.\n\nOn top of all of this, solar panels are expensive and useful, so you'd have to deal with people stealing them.\n\nThere is absolutely no way in which a solar roadway is better than just paving the road in a traditional material like concrete or asphalt and then put your solar panels off to the side or as a cover for your parking. But that doesn't get a million dollars in backing on kickstarter because it doesn't sound cool enough.\n\nSeriously, fuck those guys. They are full of shit and should know better; for my money they probably do. "
]
}
|
[] |
[
"https://m.youtube.com/watch?v=qlTA3rnpgzU"
] |
[
[],
[]
] |
|
cyliiv
|
in war, how do enemy forces know that kills they’ve sustained at the hands of snipers (chris kyle, carlos hatchcock, etc.) know to attribute the work to one sniper?
|
For both Kyle and Hatchcock (and I’m sure others), the enemy forces have nicknames and put bounties on the heads of these snipers because they’ve recognized how deadly they are. How do they know that the kills they are attributing to these individual snipers aren’t actually the work of several snipers?
|
explainlikeimfive
|
https://www.reddit.com/r/explainlikeimfive/comments/cyliiv/eli5_in_war_how_do_enemy_forces_know_that_kills/
|
{
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"text": [
"Most of the time, it was the Sniper themselves claiming the kills, and nobody contradicting them. \nThe same thing with \"tank aces\". \nThere was often a good deal of propaganda surrounding it, they played up the threat of this lone hero, when it might actually be several people. \nYou should take these stories with a grain of salt."
]
}
|
[] |
[] |
[
[]
] |
|
4tlneb
|
startup funding. what are seed/angel/rounds of funding?
|
explainlikeimfive
|
https://www.reddit.com/r/explainlikeimfive/comments/4tlneb/eli5_startup_funding_what_are_seedangelrounds_of/
|
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"Seed and angel are pretty similar. Both will generally invest into an \"idea\" or concept. All you really need to get funding from them is a somewhat believable business plan. Angel investors usually tend to not take on an organizational role (won't bother with day to day operations). Both angel and seed investors generally get a large chunk of the business' profits.\n\nFunding rounds are just more money being put into the company after certain goals are achieved and sometimes it's based on a timeline (1/2 year or yearly funding). An example would be getting more funding for an app after X number of users because we will require more infrastructure to support that many users.\n\nVenture capital is generally provided to businesses that already have a customer base and just need funds to grow. VC is generally used for growth.",
"An angel investor differs from a VC in that they are basically just a single person with a lot of money and are looking to invest. \n\nA VC on the other hand is a larger organization that raises money from hundreds or thousands of other people and invests the money on their behalf. \n\nAngel rounds and seed rounds have no legal differentiation, however, Angel rounds are generally smaller because they consists of small donations from angels. \n\nIn a seed round, you might get a combination of VCs and angels or from just VCs.\n\nAgain, there's no legal basis so calling it a \"seed round\" or an \"angel round\" is mostly at the discretion of the company announcing the fundraising. \n\nAfter the seed round is usually the \"series A\" round then the \"series B\" round. This can go indefinitely sometimes until series \"G\" with certain companies that are capital intensive like medical companies or pharmaceuticals. Afterwards is the IPO or the initial public offering which is when the company gets listed on a stock exchange for the public to invest in like on the New York Stock Exchange. \n\n(Source, I'm the CEO of Color Dating, a funded SF startup)\n\n",
"Very large investment funds have a very large amount of money (think multi-national retirement funds). After these funds do the obvious, boring work of investing in stocks, bonds, ect... it make sense for them do set aside some money for high-risk, high-return investments. They hire specialists to manage those investments. Those specialists are called \"VCs\". VCs go around looking for companies that are set up to grow very quickly if only they had a large cash injection. The standard goal for VCs is to make > 10x their investment back for the fund in around 5 years. When they do this, the VCs themselves get a percentage cut of the fund's profit.\n\nThe way the investment works is usually, \"You company has been assessed (by an independent 3rd party) to be worth around $X today. I could hand you $Y today, and we'll agree that I own Y/(X+Y) of the company afterwards and can sell my share if I want to.\" In other words, the VC adds cash value into the company, the VC then owns the percentage of the company that was added by the cash. The startup then tries to use that cash to grow the company. Hopefully, the value of the company grows to be much larger than it would have without the cash injection. Often it doesn't and the company's value fizzles away. It is expected and planned that most VC investments won't work out, but the ones that do will more than cover for the duds.\n\nAngel investors are like VCs, but they are using their own money instead of some fund's money. Seed funding is just very early, very small funding. Like, if a rich friend put in $10K to help you get started. You might agree that you had $100K of value in the company before, so now he owns 9% of a $110K company after.",
"I suffer for a living working for startups. I can answer these with an inside perspective. \n\nStartups are all about growth, and like any venture, money helps companies scale. \n\n**Angel investors** are individual people who are accredited investors per SEC guidelines to exchange cash for chucks of a privately held company, divided up into slices of \"equity.\" Equity is shares, and it's \"sold\" in percentages, e.g. \"I will seed your venture with $100,000 of my own money in exchange for 10% of your company.\"\n\nEarly angel investors get larger chunks of equity because the startup is small and hasn't had it's first valuation. You'll see later how much more it costs for smaller and smaller slices once a startup scales. \n\nFor a long time, only accredited investors (IIRC network threshold was 250k or 100k net income) could exchange cash for equity. [Now the guidelines are lifted thanks to the JOBS Act.](_URL_0_) \n\n**Angel investing** is a type of **seed funding**, but seeds can come from syndicates made up of multiple people. Generally syndicates are formed by multiple entrepreneurs who aren't SEC accredited but want to seed startups. Angel investors and syndicates will want to sit on your board and oversee how their money is being spent. \n\n**Series funding** is a different beast and is the first \"big boy\" step for startups. Series funding follows a linear alphabet, but only the first two letters have concrete definitions. \n\nLet's go on a funding trip:\n\n**Seed funding** means you have an idea but you don't have the capital to hire a CTO or another developer. You pitch to angel investors and syndicates in the hopes someone will believe in your dream. You can raise all the seeds you want to, but remember angel investors will want to sit on your board, so be careful who you pitch. \n\n**Series A** means the product you built has early potential, but you need more capital to build a company to support your venture. For example, your product can't move without marketing, and you need to hire a SEM manager and a front end dev who optimizes for SEO, or it's time to headhunt a killer sales manager and build a sales team out. \n\nAt this point between A and B, a venture can simply become cash flow positive and/or might not need to scale just yet. Actually, Series A is the terminal point for fund raising for a lot of companies. Sometimes they are bought out. Sometimes the CEO is content with the company's position and just wants to run something small until the board wants to hire a new CEO to grow it. \n\n**Series B** means the product and company is doing well, but you need to scale in order to grab a larger market share. You have a team of 20, but you can't launch in another market without building another branch. \n\nWho leads each Series funding round is equally as important as how much you raise. Andreessen Horowitz is a very prestigious VC firm, for example. \n\n**Series C through F,G,H...** is simply a need for more cash to keep growing. Ventures like FanDuel and DraftKings are sitting at Series F last I saw. \n\nGenerally, very very very large funders and Venture Capital firms will see a move to C as a signal that the venture is moving fast and a \"fear of missing out\" pushes them to lead the next fund raising round.\n\n**IPOs** are the terminal fund raising round. Initial Public Offerings are used when a company really needs to grow and turns to the general public for fundraising. Here, equity is diluted so millions of shares can be sold. IPOs make the founders very wealthy, but to employee number 20, .15% ownership in a company at IPO means his shares went from 1,500 of 1,000,000 of shares of a company worth $10B to 1,500 of 50,000,000 at $50 a share. After the 180 day lockup, he's walking away with 75k (or whatever the market price is). \n\nMoney wise, it's better to be bought out than to go public for non-C level or non-founders. \n\nCareer wise, it's better to go public. Criteria for moving up to C-level means being with a company that went public, believe it or not. Competition is crazy, and surviving an IPO gives a candidate a HUGE edge over other candidates. \n\nHope this answered it all!"
]
}
|
[] |
[] |
[
[],
[],
[],
[
"https://www.entrepreneur.com/article/252322"
]
] |
||
3ligj9
|
why do world-renowned actors/actresses, who have almost no risk of ever being in financial trouble, sometimes do terrible movies?
|
Redbox. Redbox constantly has five or six terrible movies that have household names in the lead roles. Please explain.
|
explainlikeimfive
|
https://www.reddit.com/r/explainlikeimfive/comments/3ligj9/eli5_why_do_worldrenowned_actorsactresses_who/
|
{
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"cv6kwe8",
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"text": [
"Because they can make a fat pile of cash for almost no work. In a lot of those terrible movies the big actors only need to show up for like 2 days, shoot all their scenes, and then cash the check.",
"There are a few things at play here.\n\n1, They could read a script that is awesome and sign a contract for the movie, then the director and/or editor can fuck the entire thing up - it'll look vastly different from what the script made you think of to the finished result.\n\n2, They have their agent/agency pick the movies for them based on \"what's best for them\" and end up in some shitpile movie unexpectedly.\n\n3, They could be like Nic Cage and not handle money (or have money managers screw them over) and NEED to take on the role to settle some debts - or real debts. A 10000 sqf house in Holmby Hills isn't cheap and if they didn't make any good movies the prior year they might run dry... plus publicists, agents, assistants, luxury cars, travel and stuff...\n\nIt can also be movies that were made before they were famous and suddenly they have a giant blockbuster and the owners of the earlier films re-release them to cash in on the (now) famous name.\n\n",
"It seems that was because that is part Redbox's (and Netflix and Hulu's) business model.\n\nThe more popular a movie is, them more expensive it is for them to license. So the trick is to find bad movies they can get for cheap, but have people in it who are famous enough people will see the movie because of them. Some actors make a lot of movies, and many are forgettable. But if Redbox waves *Love Potion #9* in your face, and you say to yourself, hey, that Sandra Bullock is pretty good, you might rent it.\n\n"
]
}
|
[] |
[] |
[
[],
[],
[]
] |
|
mp5t0
|
the categorical imperative
|
explainlikeimfive
|
http://www.reddit.com/r/explainlikeimfive/comments/mp5t0/eli5_the_categorical_imperative/
|
{
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"c32pmlu",
"c32ps3j",
"c32pmlu",
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"score": [
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],
"text": [
"Short version: Only act in a certain way if you can in good conscience say that people should always act in that way.\n\ne.g. you should not murder because if everyone went around murdering people, society would collapse.",
"Act as though your every action creates a universal rule requiring everyone else to act in the same way under the same circumstances.",
"Short version: Only act in a certain way if you can in good conscience say that people should always act in that way.\n\ne.g. you should not murder because if everyone went around murdering people, society would collapse.",
"Act as though your every action creates a universal rule requiring everyone else to act in the same way under the same circumstances."
]
}
|
[] |
[] |
[
[],
[],
[],
[]
] |
||
1ppl5d
|
how did the birthday song's melody become the global birthday tune? even in different languages, the melody is the same.
|
I know it's the same for English, Spanish, Portuguese and Italian.. Even though the lyrics are very different.
|
explainlikeimfive
|
http://www.reddit.com/r/explainlikeimfive/comments/1ppl5d/eli5_how_did_the_birthday_songs_melody_become_the/
|
{
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"text": [
"Started in America, translated into 18 languages, catchy as heck and that's likely why it was accepted into several cultures' traditions.\n\nwarner owns the rights, public performance could be subject to royalties. mobile, sorry: \n\n_URL_0_",
"For starters, the original lyrics were *not* \"Happy Birthday to You...\" etc. The melody is [from 1893](_URL_0_). Unfortunately, the Wikipedia article is focused primarily on the copyright status, and the melody, being older, is clearly not copyrighted, while the lyrics might be (depending on who you ask, but IMHO it's highly unlikely since they published before 1923, which is the cutoff date for modern copyrights, but IANAL). That means most of the discussion is about the lyrics and not the melody. \n\nPerhaps the public domain status of the melody made it particularly easy to use in other countries. Replacing the lyrics would weaken any claim of copyright infringement (though using a straightforward translation could still expose one to liability). Ultimately, this most likely stems from Americanization, wherein other countries' cultures become more like that of the USA. Happy Birthday is a traditional American birthday song, and restaurants in other countries may be able to get away with non-English performances of it.\n\nOf course, this is pure speculation. If someone with greater knowledge of the field (or actual sources) wants to contradict me, please feel free.",
"It's not.\n\nMuch like a lot of other areas in US culture, it's been adapted to a lot of palces, but it's far from *the* global birthday song. Every culture I'm aware of still has a traditional birthday song of their own, they just also happen to know the American one, too.\n\nFor example, the traditional Mexican birthday song is [Las Mañanitas](_URL_0_), and is often (at least in the US) sung immediately before the [Spanish-translated version](_URL_1_) of Happy Birthday.",
"I would imagine it's become popular globally for two reasons:\n\n* It's not musically complex. \n\n* The lyrics have a sum total of five distinct words and a name in them. Not hard to translate into any language."
]
}
|
[] |
[] |
[
[
"http://en.m.wikipedia.org/wiki/Happy_Birthday_To_You"
],
[
"http://en.wikipedia.org/wiki/Happy_Birthday_to_You"
],
[
"http://www.youtube.com/watch?v=BL_cDdLwV9c",
"http://www.youtube.com/watch?v=kaonnn7yCkQ"
],
[]
] |
|
21c0l5
|
why am i always reading about schools in america sanctioning students for weird reasons?
|
Recent examples:
_URL_1_
_URL_3_
_URL_0_
_URL_2_
My immediate suspicion is that the media is not telling the whole story and sensationalizing some aspect of it. But what's the deal? Why get suspended for shaving your head.
edit:format
|
explainlikeimfive
|
http://www.reddit.com/r/explainlikeimfive/comments/21c0l5/eli5why_am_i_always_reading_about_schools_in/
|
{
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"cgbkpqp",
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],
"score": [
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"text": [
"1) We have a hungry population waiting to rage over pretty much anything.\n\n2) Our various media outlets know this, and are just waiting to pounce on any story they can present or even blow out of proportion to get ratings for people.\n\n3) We have over 300 million people. With how many of them are students, it's not hard to find a few cases of odd disciplinary actions.\n\n4) We're a large country with diverse religiously or politically driven social climates. There are plenty of places where these disciplinary actions could fly, while seeming odd or unacceptable at the national or international level.",
"I think it partly involves the personality type that goes into the field of school administration. A lot of uninspired minds who get genuine satisfaction from enforcing technical points of rules and don't grasp the big picture, who would fail utterly in the business world. ",
"Because school policies are often decided by [concerned parents] (_URL_0_) who have little or no conception of a mindset beyond their own reasoning, biases and prejudices. \n\nThey think that if the children of a school don't conform to their own stylistic preferences, it will somehow \"disrupt\" the education process. "
]
}
|
[] |
[
"http://www.clickorlando.com/news/africanamerican-girl-faces-expulsion-over-natural-hair/-/1637132/23160118/-/ajcxtsz/-/index.html",
"http://www.foxnews.com/us/2014/03/25/girl-barred-from-school-for-shaving-her-head-to-support-friend-with-cancer/",
"http://www.foxnews.com/us/2014/03/18/high-school-senior-jailed-kicked-out-school-and-may-lose-army-dream-because/?intcmp=latestnews",
"http://abclocal.go.com/wls/story?section=news/national_world&id=9445255"
] |
[
[],
[],
[
"https://www.youtube.com/watch?v=Qh2sWSVRrmo"
]
] |
|
6l0rvu
|
[WW2] While looking at some history books I noticed there was a 6th landing beach at Normandy, code named BAND. What happened?
|
Seems most people think it was canceled due to flooding by the Germans or because of German Naval Presence. Can anyone confirm the story behind this?
|
AskHistorians
|
https://www.reddit.com/r/AskHistorians/comments/6l0rvu/ww2_while_looking_at_some_history_books_i_noticed/
|
{
"a_id": [
"djqr8g5"
],
"score": [
2
],
"text": [
"Here's an answer by /u/respectart from 10 months ago: _URL_0_\n\nIt seems to have been a beach given a name for planning but with no intentions of making a landing."
]
}
|
[] |
[] |
[
[
"https://www.reddit.com/r/AskHistorians/comments/4zim86/band_the_sixth_dday_beach/d708g93/"
]
] |
|
967dlj
|
do different types of radiation have different temperatures?
|
[deleted]
|
explainlikeimfive
|
https://www.reddit.com/r/explainlikeimfive/comments/967dlj/eli5_do_different_types_of_radiation_have/
|
{
"a_id": [
"e3y90l3"
],
"score": [
6
],
"text": [
"Temperature is a property of matter. Radiation doesn't have a temperature, however it has an energy (per photon) which can result in a temperature increase when a photon interact with matter.\n\n[edit] [This chart](_URL_0_) gives the energy range for different type of radiations.\n\n[edit2] Radiation can be emitted (via a process called black body radiation) by matter. Which wavelength is emitted depends only on the temperature of the emitting matter. Is this what your are thinking about?"
]
}
|
[] |
[] |
[
[
"https://upload.wikimedia.org/wikipedia/commons/thumb/3/30/EM_spectrumrevised.png/1920px-EM_spectrumrevised.png"
]
] |
|
4ewk6q
|
why in trains most people hate sitting on a back facing seat?
|
[deleted]
|
explainlikeimfive
|
https://www.reddit.com/r/explainlikeimfive/comments/4ewk6q/eli5_why_in_trains_most_people_hate_sitting_on_a/
|
{
"a_id": [
"d23xaa6",
"d23xunn"
],
"score": [
6,
2
],
"text": [
"Some people get motion sickness when they aren't facing the direction of travel. It's not even close to \"most\" people. \"Most people\" don't suffer motion sickness at all. ",
"Slightly off topic but I know back in the 80's they were talking of reversing the seats on aircraft as there was evidence your chance of survival was greater facing away from the impact. So maybe anyone bitching about having to sit in that position on a chair you can inform would probably better survive in a crash.\n\nWell it might shut them up....."
]
}
|
[] |
[] |
[
[],
[]
] |
|
3j366n
|
What were the first millitary uniforms that we know of?
|
AskHistorians
|
https://www.reddit.com/r/AskHistorians/comments/3j366n/what_were_the_first_millitary_uniforms_that_we/
|
{
"a_id": [
"cum7j2a",
"cum8ex4"
],
"score": [
20,
55
],
"text": [
"To compound on this question: what was the first organized military that we know of?",
"I imagine that would depend on how you'd define a uniform.\n\nIf a group of warriors in a tribe choose to ornament themselves in a distinct way, is that a uniform? "
]
}
|
[] |
[] |
[
[],
[]
] |
||
2imefp
|
how does cheat detection in games work?
|
Things like VAC and punkbuster etc. how do they work?
I swear I'm not a cheater guys
|
explainlikeimfive
|
http://www.reddit.com/r/explainlikeimfive/comments/2imefp/eli5_how_does_cheat_detection_in_games_work/
|
{
"a_id": [
"cl3fbpk"
],
"score": [
5
],
"text": [
"at the easiest level, you take the executable binary files that the game is running. take the bits in the program and run them thru a math function called a checksum. the checksum produces a number. this number will change if any of the bits changes. the publisher knows what the unmodified binary's checksum number is. if your executable is anything but the original checksum, you're not allowed to pass.\n\nother ways check the data that's in memory. if the original program didn't modify the data and the data's changed from the last time, something's messing with the data."
]
}
|
[] |
[] |
[
[]
] |
|
4gfq4p
|
why did most countries keep the roman alphabet but switch from roman numerals?
|
explainlikeimfive
|
https://www.reddit.com/r/explainlikeimfive/comments/4gfq4p/eli5_why_did_most_countries_keep_the_roman/
|
{
"a_id": [
"d2h4tqk",
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"score": [
2,
2
],
"text": [
"I don't know about the first part but the practice side of why we don't use Roman numerals is because writing large numbers is not efficient with them, also it is very easy to misinterpret what they say. Most people won't confuse 6 and 7 but more will confuse VI and VII. ",
"Mostly because doing maths with Roman numerals is harder, not being a positional notation.\n\nIIRC Charles Seife's [excellent book on zero](_URL_0_) covers it quite well."
]
}
|
[] |
[] |
[
[],
[
"https://en.wikipedia.org/wiki/Zero%3A_The_Biography_of_a_Dangerous_Idea?wprov=sfla1"
]
] |
||
tnh5c
|
Is it possible to get sick from your own cold?
|
What I mean is: Let's say I get a cold, and end up getting my friend sick. After I've recovered, can I get a cold from the friend that I gave it to?
|
askscience
|
http://www.reddit.com/r/askscience/comments/tnh5c/is_it_possible_to_get_sick_from_your_own_cold/
|
{
"a_id": [
"c4o46h2"
],
"score": [
3
],
"text": [
"You can catch the same cold, however if the strain hasn't evolved yet, the odds are that your immune system will already have the immunity built up from it the first time. So, if you were to come in contact with said cold again, your body would just fight it off much faster than the first time, when your body needed to produce the specific cytotoxic T-cells to attack the cold. The second exposure would already know how to create the cytotoxic T-cells to combat the cold and you would probably not even know that you caught it again."
]
}
|
[] |
[] |
[
[]
] |
|
5z21lc
|
how is film made for cameras?
|
I have always wondered how it was created to be light sensitive and how they make different types of films that give different looks.
|
explainlikeimfive
|
https://www.reddit.com/r/explainlikeimfive/comments/5z21lc/eli5_how_is_film_made_for_cameras/
|
{
"a_id": [
"dev0q7b"
],
"score": [
2
],
"text": [
"Photo sensitive papers and films are made using a form of silver. The silver halides have a very low activation threshold, and the zap of a photon is enough to knock pieces off the halide, changing it's chemical structure. \n\nThe film is made by using a substrate which is anything you use to hold the image. It could be plastic, paper, cellulose, etc. The base substrate is embedded with the silver halides and these impregnate the film or paper. It is then dried and packaged in light proof containers. \n\n\nThe image is developed using a developer compound like D76, which is a powder dissolved into water to form a liquid developer. It darkens or tarnishes the exposed silver particles. \n\nThe reaction will keep going until a chemical neutralizer called stopbath is used. Stopbath reacts with the developer and neutralizes it so it stops developing. Without it, an image would continue to get darker and darker over time as the developer continued to work long after it was in a darkroom. \n\nFinally the film or paper is run through a chemical called a fixer. It renders the rest of the silver halides inert and they will no longer react with light. At this point you can flip the lights on because you have a permanent photograph or negative, once you wash it off. \n\nA fun fact, the silver collected in the film and paper ends up saturating the fixer tray. It is possible to recover the silver from the liquid by chemically treating it and then refining. It doesn't amount to much but it's still pretty cool. \n\n\n"
]
}
|
[] |
[] |
[
[]
] |
|
7v03qx
|
When was the last time the moon was hit by a large enough meteroid that it would have been visible from earth?
|
askscience
|
https://www.reddit.com/r/askscience/comments/7v03qx/when_was_the_last_time_the_moon_was_hit_by_a/
|
{
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"dtous6d",
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7,
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],
"text": [
"There are periodic flashes on the moon (a few have even been recorded) that are thought to be from meteor strikes. Unfortunately, because the moon lacks and atmosphere, we do not get as big of a fireworks show as we do when meteors hit the Earth. This means we don't see most of the ones that impact even though they are about as frquent as those that impact the Earth.",
"If you're looking for something clearly visible, so it's a quite large object, the only one that I've heard of is the hypothesis that the Giordano Bruno crater was formed in an impact witnessed by monks in Europe about 1000 years ago.\n\nIf imaging and telescopes are fair game, I even know someone that has video of something small striking the moon from about a decade ago.",
"[Here](_URL_0_) is one from March 17th, 2013. The flash was imaged from earth, and LRO was able to image the resulting crater, showing both before and after the impact."
]
}
|
[] |
[] |
[
[],
[],
[
"https://www.nasa.gov/content/goddard/nasas-lro-spacecraft-finds-march-17-2013-impact-crater-and-more"
]
] |
||
2rt2w1
|
what are green olives stuffed with and why do they do it?
|
Also how do they stuff them? In a factory? Hand-stuffed by elves?
|
explainlikeimfive
|
http://www.reddit.com/r/explainlikeimfive/comments/2rt2w1/eli5_what_are_green_olives_stuffed_with_and_why/
|
{
"a_id": [
"cnizuzh",
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],
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3,
2,
2
],
"text": [
"They're traditionally stuffed with pimiento, a sweet red pepper. I've seen them stuffed with all kinds of things, though - jalpeno, bleu cheese, almonds, garlic....",
"[Here](Stuffed Olives: _URL_0_) is a 'How Its Made' on the subject that explains it very well.",
"Taking the pit out of the olive leaves a big hole. They put in a piece of pimento, a chili pepper. It's all done with machines...run by elves."
]
}
|
[] |
[] |
[
[],
[
"http://youtu.be/MdCqelSoCqQ"
],
[]
] |
|
1amb97
|
what the point of pantone colors is.
|
explainlikeimfive
|
http://www.reddit.com/r/explainlikeimfive/comments/1amb97/eli5_what_the_point_of_pantone_colors_is/
|
{
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],
"text": [
"You can do a lot with the four basic colours (Cyan, Magenta, Yellow, Black), but not all. Mixing of them is not perfect and you simply cannot recreate a certain, very specific shade. You need to go beyond paints and mix specific pigments (stuff that makes colour in paint) and there are 15 of them. Pantone also contains metallic and fluorescent colours, which also cannot be recreated by CMYK. \n\nIt's quite important if you want a consistent symbol (like company logo, or a flag and whatnot) to be printed all over the world exactly the same. Most home printers would still convert it to CMYK, but in offset printing (the way to print a lot of stuff) it's quite common.\n\nEDIT: Also, instead of printing 4 colours on one sheet of paper and making 4 plates/stencils and counting that each colour gets printed on exactly the same spot, you only need one. ",
"So, to answer this question I'm going to need a [picture](_URL_0_). \n\n* The outer circle represents all the colours that are visible to the human eye. \n* The large yellow border represents all the colours that can be shown on a computer monitor by mixing red, green and blue light (RGB). This represents a huge chunk, but by no means all visible colours.\n* The small blue border represents the colours in print media, books, magazines, etc. (CMYK). This is just a small subset of all the visible colours and is a lot smaller than RGB. However, all these colours can be made by mixing four basic inks, which makes for cheap production.\n* The brown border represents the colours in the Pantone system. There are far more colours here than you can get from the simpler four-colour process, but still far fewer than RGB and ultimately only a small subset of the visible colours is available. \n\nYou can get a much wider range of colours by using Pantone, but this comes at a cost - one ink is required per colour. Four CMYK inks can reproduce a full colour photograph to an acceptable standard. However, if you want your company logo to really stand out on the page, maybe Pantone is the way to go."
]
}
|
[] |
[] |
[
[],
[
"http://3.bp.blogspot.com/-GlRUExzCWos/T7_vxHtZ4qI/AAAAAAAAAFU/4z2-VUetVSc/s1600/gamut.jpg"
]
] |
||
2a5zx4
|
if we ignore the budget and just constantly create debt, why does the government even bother collecting taxes(usa)?
|
explainlikeimfive
|
http://www.reddit.com/r/explainlikeimfive/comments/2a5zx4/eli5_if_we_ignore_the_budget_and_just_constantly/
|
{
"a_id": [
"cirt44m"
],
"score": [
2
],
"text": [
"Because we have to pay interest on the debt and nobody is going to lend money to a country that has zero income."
]
}
|
[] |
[] |
[
[]
] |
||
74l0ln
|
How did Stalin personally react to Hitler's 1941 invasion and launching of Operation Barbarossa? I've read he had a mental breakdown and disappeared for several days. Is this true?
|
AskHistorians
|
https://www.reddit.com/r/AskHistorians/comments/74l0ln/how_did_stalin_personally_react_to_hitlers_1941/
|
{
"a_id": [
"do0cha6"
],
"score": [
3
],
"text": [
"If you can read russian: [this](_URL_1_) or [this](_URL_0_) (И. Пыхалов, \"Великая оболганная война\")\n\nContent: sources about breakdown and disappearing are Khruschev and Mikoyan. Zhukov, Dimitrov and Kaganovich are against it. Visitors log supports latter - Stalin was in Kremlin and received many visitors."
]
}
|
[] |
[] |
[
[
"http://militera.lib.ru/research/pyhalov_i/10.html",
"http://wiki.istmat.info/%D0%BC%D0%B8%D1%84:%D0%BD%D0%B0%D1%87%D0%B0%D0%BB%D0%BE_%D0%B2%D0%BE%D0%B9%D0%BD%D1%8B"
]
] |
||
ao57xt
|
How did the Soviets view the New Deal?
|
Did they see it as a step towards communism?
|
AskHistorians
|
https://www.reddit.com/r/AskHistorians/comments/ao57xt/how_did_the_soviets_view_the_new_deal/
|
{
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"efyfiok"
],
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"text": [
"During a visit to the Soviet Union in 1934, H.G. Wells interviewed Joseph Stalin and asked him what he thought of Franklin Roosevelt and the New Deal, and whether he saw it as a stepping stone to socialism. \n\nI've included Stalin's reply below, but to summarize, he viewed the New Deal as fatally limited - attempting to mitigate the symptoms of the Great Depression while not addressing the economic system that created it. Stalin further elaborated that the New Deal working within the restraints of capitalism meant that it ultimately did not threaten the power capitalists held over the economy, key infrastructure, their employees and the state; and that while they held such power any moves by Roosevelt that targeted the underlying foundations of capitalism would be ultimately defeated. \n\n > The United States is pursuing a different aim from that which we are pursuing in the USSR. The aim which the Americans are pursuing arose out of the economic troubles, out of the economic crisis. The Americans want to rid themselves of the crisis on the basis of private capitalist activity, without changing the economic basis. They are trying to reduce to a minimum the ruin, the losses caused by the existing economic system.\n\n > Here, however, as you know, in place of the old, destroyed economic basis, an entirely different, a new economic basis has been created. Even if the Americans you mention partly achieve their aim, ie, reduce these losses to a minimum, they will not destroy the roots of the anarchy which is inherent in the existing capitalist system. They are preserving the economic system which must inevitably lead, and cannot but lead, to anarchy in production. Thus, at best, it will be a matter, not of the reorganisation of society, not of abolishing the old social system which gives rise to anarchy and crises, but of restricting certain of its excesses. Subjectively, perhaps, these Americans think they are reorganising society; objectively, however, they are preserving the present basis of society. That is why, objectively, there will be no reorganisation of society.\n\n > Nor will there be planned economy. What is planned economy? What are some of its attributes? Planned economy tries to abolish unemployment. Let us suppose it is possible, while preserving the capitalist system, to reduce unemployment to a certain minimum. But surely, no capitalist would ever agree to the complete abolition of unemployment, to the abolition of the reserve army of unemployed, the purpose of which is to bring pressure on the labour market, to ensure a supply of cheap labour. You will never compel a capitalist to incur loss to himself and agree to a lower rate of profit for the sake of satisfying the needs of the people.\n\n > Without getting rid of the capitalists, without abolishing the principle of private property in the means of production, it is impossible to create planned economy. [...] In speaking of the impossibility of realising the principles of planned economy while preserving the economic basis of capitalism, I do not in the least desire to belittle the outstanding personal qualities of Roosevelt, his initiative, courage and determination. Undoubtedly Roosevelt stands out as one of the strongest figures among all the captains of the contemporary capitalist world. That is why I would like once again to emphasise the point that my conviction that planned economy is impossible under the conditions of capitalism does not mean that I have any doubts about the personal abilities, talent and courage of President Roosevelt.\n\n > But if the circumstances are unfavourable, the most talented captain cannot reach the goal you refer to. Theoretically, of course, the possibility of marching gradually, step by step, under the conditions of capitalism, towards the goal which you call Socialism in the Anglo-Saxon meaning of the word, is not precluded. But what will this “Socialism” be? At best, bridling to some extent the most unbridled of individual representatives of capitalist profit, some increase in the application of the principle of regulation in national economy. That is all very well. But as soon as Roosevelt, or any other captain in the contemporary bourgeois world, proceeds to undertake something serious against the foundation of capitalism, he will inevitably suffer utter defeat. The banks, the industries, the large enterprises, the large farms are not in Roosevelt’s hands. All these are private property. The railroads, the mercantile fleet, all these belong to private owners. And, finally, the army of skilled workers, the engineers, the technicians, these too are not at Roosevelt’s command, they are at the command of the private owners; they all work for the private owners.\n\n > We must not forget the functions of the State in the bourgeois world. The State is an institution that organises the defence of the country, organises the maintenance of “order”; it is an apparatus for collecting taxes. The capitalist State does not deal much with economy in the strict sense of the word; the latter is not in the hands of the State. On the contrary, the State is in the hands of capitalist economy. That is why I fear that in spite of all his energies and abilities, Roosevelt will not achieve the goal you mention, if indeed that is his goal. Perhaps in the course of several generations it will be possible to approach this goal somewhat; but I personally think that even this is not very probable. \n\n_URL_0_\n\nThe Communist Party USA initially had a cold, hostile view of Roosevelt - Stalin's Third Internationale held that social democracy and social democratic parties constituted \"social fascism,\" and constituted a greater threat to the development of socialism than Hitler or Mussolini's fascism. This was influenced by an ugly recent history of conflict between social democratic and communist parties, namely the Social Democratic Party of Germany (SPD) and Communist Party of Germany (KPD), and was a contributor to their failure to unite and prevent Hitler's Nazi Party (NDSAP) from taking power in the 1933 elections. The subsequent brutal suppression of both the SPD and KPD influenced a shift in favor of forming broad \"popular fronts\" against fascism and reactionary movements - in the CPUSA, this manifested in a shift from heavy attacks on Roosevelt to tacit support for him and some new Deal Policies. \n\nSee this 1936 CPUSA [elections platform](_URL_1_). While the CPUSA ran their own candidates that election, the platform is noticeably free of serious attacks on FDR and the Democratic Party. It focuses primarily on emphasizing the damage that \"Hoover-Republicans\" will cause if restored to power, characterizing Roosevelt as someone who too easily compromises with \"the camp of reaction\" rather than an agent of it.\n"
]
}
|
[] |
[] |
[
[
"https://www.newstatesman.com/politics/2014/04/h-g-wells-it-seems-me-i-am-more-left-you-mr-stalin",
"https://ia801802.us.archive.org/35/items/CommunistElectionPlatform1936/360800-cpusa-communistelectionplatform.pdf"
]
] |
|
bgh72l
|
what is an easy way to explain the basic concept of music theory ?
|
explainlikeimfive
|
https://www.reddit.com/r/explainlikeimfive/comments/bgh72l/eli5_what_is_an_easy_way_to_explain_the_basic/
|
{
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"Start playing a couple of bars on a piano then hit a wrong note. Nothing familiar, but it sounded nice until you hit that wrong note. \n\nYou didn't know the song, so as far as you know it was exactly as the composer intended, but you just *know* it was wrong. \n\nMusic theory is the theory that every note/chord has an ideal next note/chord. With enough AI, we could program the \"perfect\" ending to song. \n\nWe've worked out certain riffs that tie onto other riffs and transition into others, but the rules are always changing, and there are always exceptions. \n\nThink [Ice Ice Baby](_URL_0_) vs [Under Pressure](_URL_1_). Both are \"good\" songs, despite starting the same way.",
"When two different pitches are played at the same time, that's called harmony. Harmonies can be consonant or dissonant.\n\nWhen we look at the mathematical frequencies of the two notes, they make a ratio. If the ratio is nice and easy, like 1/2 or 2/3 or even 3/5, they match up and sound nice. We call that consonance. If the ratio is weird like 9/17 or something, they don't match up very well and sound like they are clashing. We call that dissonance.\n\nGenerally speaking, people like to hear consonance more than dissonance. But sometimes musicians will deliberately use dissonance (as long as it isn't too bad) that resolves to consonance because it makes tension and then release.\n\nIt's like how in a movie where the evil guy bad is about to kill the hero but then the hero defeats him at the last minute. If the whole movie were just rainbows and lollipops there's no tension, no conflict. It would be boring. In the same way, musicians will tend move from consonance and dissonance and back again and all around, which makes an interesting piece of harmony.\n\nOf course consonance and dissonance are not a black and white thing. There are different varieties and flavors of them. In the same way that an artist will mix reds and blues to make a new shade of purple, a musician can combine notes and harmonies in different ways to make an interesting piece of music."
]
}
|
[] |
[] |
[
[
"https://www.youtube.com/watch?v=rog8ou-ZepE",
"https://www.youtube.com/watch?v=YoDh_gHDvkk"
],
[]
] |
||
1v0xa3
|
why do we give prisoners razors to shave if they always use them to make shanks?
|
Just watching America's toughest prisons and thought they had far too many utensils given to them that could be used for shanks. Is there anyway to just not give prisoners sharp objects? And if yes, is it a futile exercise as they probably will find other ways of making shanks? Ty.
|
explainlikeimfive
|
http://www.reddit.com/r/explainlikeimfive/comments/1v0xa3/why_do_we_give_prisoners_razors_to_shave_if_they/
|
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"You can make a shank out of almost anything. Just gotta find something that's hard but can be given a sharp edge or a point. You can melt things, break things, whittle things, scrape things, etc. ",
"Prisoners have barbars",
"It's true as listed before; prisoners can make shanks out of nearly anything. I watched a prison documentary where a prisoner described how he fashioned a national geographic magazine into a functioning weapon. Prisoners are only given razors when they show that they can be trusted with them, and won't hurt themselves or others. High security inmates are forbidden from having anything easily made into a weapon, and are shaved by someone else every few days.",
"I'm just gonna leave this here: \n\n_URL_0_",
"From my experience in county jail, razors aren't something inmates get to keep. They are issued once a week, you have to sign for yours, and a couple hours later you turn it in and get your name checked off. The guards inspect the razor for damages (missing blades), and if anything is amiss there are consequences.\n\nToothbrushes are much easier to make shanks out of, anyway.",
"I vote they wax. ",
"For most general population inmates, the razors are accounted for and controlled. Inmates are allowed a certain number of razor blades and must have exactly that number in their cell. When the cells are inspected, as they are frequently, if an inmate is missing a blade, the inmate may go from general population down to max custody. \n\nIf an inmate has to dispose of a blade, he can't just throw it in the trash. He has to turn it into a guard who will dispose of the blade."
]
}
|
[] |
[] |
[
[],
[],
[],
[
"http://www.cracked.com/quick-fixes/9-regular-objects-turned-into-insane-prison-weapons/"
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] |
|
4oioeb
|
We have hot air balloons, and helium balloons but why not hot helium balloons?
|
I know that suggesting Hot Hydrogen is a no-no, but wouldnt heating helium provide more lift than traditional methods or is there something I am missing here? I know heating helium would not be as simple as heating air obviously, but Im sure there is a way.
|
askscience
|
https://www.reddit.com/r/askscience/comments/4oioeb/we_have_hot_air_balloons_and_helium_balloons_but/
|
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"As with so many things: It would be possible, but what's the point?\n\nA hot air balloon needs to be reheated regularly to compensate for the heat loss. Because the balloon contains just air, it can use a relatively simple design with the bottom being open, so the burner can easily heat up the air. \n\nIf you'd replace the air in the balloon with helium, you'd quickly lose most of the helium due to diffusion through the opening. So you'd have to make the balloon more or less airtight (or rather: helium tight, helium molecules are smaller than nitrogen and oxygen that make up the air). And doing that makes heating it more difficult. You can build something that has the heater enclosed inside the balloon.\n\nBut what do we use balloons for nowadays? Hot air balloons are purely recreational, there's no need to make them more efficient. And we have weather balloons and balloons that carry other types of instrumentation. But for those, hydrogen is typically used because it's much cheaper than helium (though helium would work as well). And zeppelins have been very effectively replaced by airplanes.\n\nSo that brings me back to my original point: Yes, it's possible, but there's no real application for it, so people don't bother with it.",
"Largely because it is entirely unnecessary. We use hot air balloons because hot air is less dense than unheated air, resulting in buoyancy. Unheated Helium is also buoyant in the existing atmosphere, therefore it would just be a useless energy sink. ",
"Something to be aware of is that the marginal return on lift for heating helium isn't that great because helium is already so light: 1000 cubic feet of helium at STP lifts about 66 lbs. 1000 lbs of cubic feet of helium at 300 c lifts about 71 lbs.\n\n\n",
" - It would have the inconvenients of both, since you would need both a heater *and* helium.\n\n - It would not lift much more than either (remember, it's not helium or hot air that is ~~\"light\"~~ “pulling upwards”, rather the balloon is floating in the atmosphere because it is extremely light - since helium is already extremely light, there is not much to gain by making it lighter).\n\n - Also, counter-intuitively, a (cold) H or He balloon is at ambient pressure and therefore “slack”. A hot balloon is pressurized, and will tend to leak quite a bit more, so you're losing helium somewhat faster than with a cold balloon. So over time this is going to float even worse than a cold balloon!",
"I think people are dancing around why not.\n\nAir is also on the outside of the hot air balloon. The reason the balloon flies is because the air inside of the balloon is less dense than the air outside of it.\n\nAnother way to think about that is that there's less \"air\" in the balloon, versus how much air would be in that space if the balloon weren't there (or if it was filled with ambient temp air). The air taking in the extra energy meant that it would prefer to take up more space. \n\nIf it can help it, air will do one or the other: Be hot or be compressed. If air gets compressed by force, it sheds heat.\n\nSo this is why hot air rises; hot air accepted the heat, and can either shed the heat or increase its volume. If it increases its volume in a hot air balloon, some of that air escapes the balloon (the key concept in why hot air balloons work).\n\nNormally when air gets hotter via the sun in the atmosphere, there's nothing to constrict this \"hot pocket/bubble\", so it gets bigger (we call this wind). The hotter air displaces molecules vs cold air, it weighs less, and wants to go up. The colder air is heavier and wants to fall. \n\nHere's another way to look at it: It takes energy to decompress air.\n\nIf you force air into a tank (air compressor) the tank heats up. If you let it sit and cool off, after a while that tank will reach ambient temperature. It lost energy into the environment to fit the air into a smaller space. When you decompress it again, it wants that heat back, and absorbs it from the environment (it gets cold). This is how ACs work, and this is why your can of compressed air feels cold when you use it.\n\nOK - we're almost there!\n\nWhen you heat air in a hot air balloon, you're effectively making less air in the balloon relative to outside the balloon (remember, it's open and the atmosphere vents into/out of the balloon: there's somewhere for the \"extra\" air to go.\n\nHelium atoms are small, and tend to get out of containers that we put them into. We can't put helium into a rubber balloon. Because of this, the vessel we normally put helium into is mylar, and **mylar doesn't expand**. \n\nSo while you could add heat to the helium to decrease the pressure of the helium, it wouldn't make a lick of difference if the vessel can't expand to take up more volume. If it doesn't take up more volume with the same amount of helium, it didn't actually get lighter as far as the atmosphere is concerned.\n\nIn short: **It's not the heat in the air that makes the hot balloon rise, it's that there's less of it inside the balloon after you've heated it up and vented some of the air molecules out. Taking up more space with less air! :-).**\n\n*edit* fun note: If you could have a container that was light as mylar but could also keep its shape (not collapse) while under vacuum, it would be completely optimal. The reason we don't do this is largely the same as the reason we don't do helium hot air balloons: Material Science. We don't have materials that have the properties we would need. \n\n\n",
"I think one thing you may be missing here is that when a hot air balloon loses heat, it begins to descend allowing the balloon to land safely. A helium balloon would rise on it's own in theory, so the only reason to heat it would be to make yourself rise more quickly, but you can't go back down because cool helium still rises.",
"Would it be possible to make a vacuum balloon? I.e. have a structure of similar size as a balloon but with a vacuum in it making it lighter than a helium or hot-air balloon of similar size?\nI can understand that such a structure which contains such a big vacuum chamber would have to be incredibly strong and quickly become too heavy.\nBut how about filling a balloon with vacuum, or close to vacuum ping pong balls, or maybe containing an even smaller sub-structure?\n",
"Helium is only modernly cheap, thanks to Reagan undoing most of the reserve holding of it. It is a scientifically and technologically useful material and as such is best employed for its unique properties as a light non-reactive gas with very strong and stable bonds. Helium is a light material and as such when released escapes earth's atmosphere quite easily, the few large natural reserves of helium, one of which is the Texas panhandle are rare and are the result of beta decay being trapped by impermeable rock layers in geological stable locations, that have an old age. Additionally refinement of helium into the less common H3 isotope would yield a more energetic particle useful for fusion. In this regard utilization of a material for its given properties unique to it alone is a relatively new perspective for humanity, in this regard making a hydrogen balloon is not really a no-no, it's just maybe don't paint the hull with rocket fuel, which the Hindenburg was.",
"I think this is less of a science question and more of an economics question. Heating up air is way more economical than having both a helium tank and a fuel tank in the balloon. Also hot air balloons are inflated with big fans and the air inside is periodically released to control altitude and direction of travel.\n\nHaving a hot helium balloon would be insanely expensive as well as annoying logistically because there would then be an added limiting factor (and severely limited at that).",
"Because buoyancy is only marginally increased. Helium (or hydrogen) floats in air for exactly the same reason something floats in water - its lighter. \n\nMolecular weight of air is 29 g/mol.\nMolecular weight of helium is 4 g/mol.\nMolecular weight of hydrogen is 2 g/mol.\n\nSo, even if you use a vacuum balloon (mass = 0), the improvement of buoyancy will be marginal because both helium and hydrogen are already extremely light compared to air. A heating device and fuel will more than likely add more weight than can be possibly be gained from the extra couple % of buoyancy.\n",
"The volume of helium needed to fill the 'balloon' part of a hot air balloon would cost so much it just wouldn't be worth it. Also I remember my old high school chemistry teacher talking about a helium shortage on earth, I don't know how real that problem is but it is just one more reason why it wouldn't make sense. ",
"Something I don't see mentioned, is that we have a Helium shortage. The price of it is steadily increasing. In fact, this has sparked some new research by scientists to replace Helium in medical imaging in an effort to reduce costs. ",
"Incidentally, there's an Arthur C Clarke short story (A Meeting with Medusa) where they use a hot hydrogen balloon to explore the depths of the Jovian atmosphere.\n\nIt's only a no-no in an oxygen-rich environment",
"Besides the physical arguments made above, Helium is relatively scarce and expensive \n\n_URL_0_\n\n_URL_1_\n\nThis question is a lot like asking why pipes were ever made of Lead (toxic) instead of Gold (non-toxic, non-corrosive). ",
"Weird, I just finished working on a bunch of math regarding just this topic.\n\n_URL_0_\n\nHere's a picture link to imgur of a graph I ended up making of various \"tank\" temperatures for lifting gasses vs the relative amount of mass displacement. \n\nLong story short, He and H expand so little in proportion to heat compared to hot air, that it's really not worth the effort to heat anything other than air. \n\nYou can also see that even with heating the tanks to some really high value, using cold He instead would still provide more lift. \n\nHopefully that helps clarify things a bit. \n\n",
"We should not have helium balloons. Centuries from now, future generations will curse us for wasting helium.\n\nWe can't make it. We can't get it back if we lose it. People are filling balloons and talking funny. MRI machines need it to function. Which is a better use?"
]
}
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[] |
[] |
[
[],
[],
[],
[],
[],
[],
[],
[],
[],
[],
[],
[],
[],
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"http://www.wired.com/2015/07/feds-created-helium-problem-thats-screwing-science/",
"http://www.washingtonpost.com/wp-dyn/content/article/2010/12/12/AR2010121203375.html"
],
[
"http://imgur.com/vlm1Hjm"
],
[]
] |
|
2fz2x6
|
how accurate is the "hollywood" version of being shot?
|
A while back, for a story I was working on, I did a lot of research into gunshot wounds, but it's still difficult to me to picture the forces behind these injuries. One thing that bugs me is how movies portray being shot.
In action movies, it seems like whenever a character is shot, one of three things will happen: They will walk it off, completely unharmed, they will instantly drop dead, or they will collapse on the ground and slowly pass out with just enough time to deliver some poignant/awesome dying words.
From what I've learned, it's possible to die instantly from a gunshot wound, generic bad-guy style, but most GSWs are treatable and survivable. That doesn't mean you should be able to shrug off bullets like an action hero, but you're also not likely to instantly die.
What I'm wondering is, what about that step in between? When shot in a critical part of the body, but not enough to cause instant death, like the brain or the heart, do we really get the poignant "DON'T YOU DIE ON ME" scene we see in the movies, where a dying character has 30 seconds of lucidity to deliver his last words before peacefully falling asleep?
I guess what I'm asking is, in that situation,
1: What is the person dying of? Are they bleeding to death? Are they dying of shock? Suffocation?
(1a: The concept of dying of shock always seemed odd to me. What's killing the person there?)
2: Will they really remain both conscious and lucid, and for how long? Could they really stay that calm, or would the pain be too much?
3: Where would a person have to be shot for this to happen?
Weird questions, I know, and morbid ones too, but I'm honestly curious.
|
explainlikeimfive
|
http://www.reddit.com/r/explainlikeimfive/comments/2fz2x6/eli5_how_accurate_is_the_hollywood_version_of/
|
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"EMT/medical nut here. \n\nWhen you get shot, there are a bunch of competing forces happening at once, one or more of which could kill you. Of course, blood loss is a real problem if the bullet hits anything important, but the body can actually handle quite a bit of blood loss before dropping into an unrecoverable spiral. Even then a paramedic should be able to give you some IV fluids to stave off shock. Since you asked, shock is a medical term referring to \"inadequate perfusion\", which is Science for \"you don't have enough oxygen getting to your cells, so everything is freaking out and dying.\" Really low blood pressure (caused by not having enough blood) is the major cause of this in gunshot victims, though it can also be caused by brain damage making your blood vessels freak out and open all the way. This \"Neurogenic\" shock is basically always lethal in the field.\n\nIf the bullet didn't hit an artery and you get any kind of first aid (including stopping the bleeding yourself), blood loss isn't what's going to kill you. If you survive the first 10 minutes of being shot and there is no internal bleeding, you will probably survive to a hospital. There, it depends where you were shot, and how serious the injury is. If you got shot in the muscle of your leg or arm, it's possible the doctors can just remove the bullet and then sew you up. The muscle will eventually heal on its own, and nothing in your extremities will be life-threatening. This is why bullet-proof vests don't cover the arms.\n\nIf, however, the bullet went into your main body, you have a bigger problem. Bullets are moving really fast (duh). All that energy has to go somewhere, and if a bullet hits you in the chest, the energy is going into ripping you apart in various ways. The obvious one is the bullet hole. If the bullet missed your ribs, it will definitely be going fast enough to punch holes in your internal organs. Organs don't like this very much, and this will cause internal bleeding, which can kill you really fast. A good trauma surgeon can fix most bullet holes in time to save you, assuming the other problems don't get you. \n\nInfection is one of those problems. Opening up the chest cavity in a non-sterile area is a huge no-no in surgery, and bullets have the annoying habit of doing just that. Any old germ which might be harmless on the outside of the body might completely wreck you once it gets inside, especially once you consider that your immune system is going to be down following the massive system trauma. \n\nThe third major problem is known as cavitation. This one is a little more complicated to explain, but basically it's the damage caused by all the bullet's energy that DIDN'T go to ripping you new orifices. When the bullet hits, it creates a shockwave through the surrounding tissue that travels faster than the speed of sound in some cases. This shreds small blood vessels, destroys individual cells all over the area, causes nerve damage, and can collapse intricate systems inside your organs you need to survive. There isn't really a way to treat this at this time, and the amount and types of damage done vary basically at random.\n\nIf you get hit in a lung, this opens up a whole new can of worms. If you start bleeding into a lung, the lung will stop working (duh) and you will quickly be unable to breathe. Sometimes, air can get into the bullet wound and collapse one or both lungs. This is called a pneumothorax, and can be treated in the field by a paramedic by jabbing you with a wide-bore needle. However, collapsing the lungs does permanent damage to them, and it might cause permanent breathing problems. If you get shot in the gut, partially-digested food and bacteria from the colon spill into the body cavity, which will almost always end in a horrific infection, and possibly death. Getting hit in the kidneys or liver will cause massive blood loss, and if your pancreas somehow gets hit despite being behind literally everything else, you could get Type I Diabetes.\n\nTl;DR: DON'T GET SHOT."
]
}
|
[] |
[] |
[
[]
] |
|
127j0z
|
Could something hit the Moon like a pool cue ball and send it (or its remaining core) hurdling toward Earth?
|
Is something like this even remotely (theoretically) possible? Why or why not?
If so, how long would it take for us to notice major changes? And how long before impact?
|
askscience
|
http://www.reddit.com/r/askscience/comments/127j0z/could_something_hit_the_moon_like_a_pool_cue_ball/
|
{
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"Any impact on the moon that would be large enough to alter its orbit to intersect the earth's, would also be large enough to break the moon apart. And melt it. \n\nA back of the envelope calculation shows that, to get the moon to fall toward the earth, it would take an impact with the energy of roughly 100 million [Tsar Bombas](_URL_0_), the largest nuclear bomb ever detonated.\n"
]
}
|
[] |
[] |
[
[
"http://en.wikipedia.org/wiki/Tsar_Bomba"
]
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|
1ioqen
|
how do you real estate agents get profit if the person buying it will be on a mortgage?
|
Asked my eco teacher, still didn't help much.
|
explainlikeimfive
|
http://www.reddit.com/r/explainlikeimfive/comments/1ioqen/eli5how_do_you_real_estate_agents_get_profit_if/
|
{
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"Because a bank loans the buyers money. They give that money to the agent, who will give it to the seller (minus their fee). The buyer then pays the bank back the money borrowed, and interest. ",
"A mortgage is just a long-term loan.\n\nThe house seller contacts a real-estate agent to sell his/her house. The real-estate agent takes a fee for selling the house, let's say it's 1%.\n\nThe seller of the house wants a $100 for the house. This means that the real-estate agent will set their fee at 1$, making the total-cost for the buyer 101$. So the seller gets $100, and the real estate agent gets 1$.\n\nThe buyer contacts a bank and takes out 101$, give 1$ to the real estate agent and 100$ to the seller of the house.",
"The bank pays the seller the full price of the property. The realtor takes their percentage cut. The buyer pays off the loan over several years or decades."
]
}
|
[] |
[] |
[
[],
[],
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|
12nzd4
|
What would happen if a spaceship traveling at or near the speed of light collided with a planet or some other large object?
|
askscience
|
http://www.reddit.com/r/askscience/comments/12nzd4/what_would_happen_if_a_spaceship_traveling_at_or/
|
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"_URL_1_\n\n\n\n\"A 1 kg mass traveling at 99% of the speed of light would have a kinetic energy of 5.47×1017 joules. In explosive terms, it would be equal to 132 megatons of TNT or approximately 32 megatons more than the theoretical max yield of the tsar bomba, the most powerful nuclear weapon ever detonated. 1 kg of mass-energy is 8.99×1016 joules or about 21.5 megatons of TNT.\"\n\n_URL_0_\n\nIt weighs around 2000 tons. Let's assume our spaceship weighs the same.\n\n132 megatons*2000 tons=264 teratons of TNT\n\nThat's a similar amount of energy to a earthquake of magnitude 10 on the Richter Scale. It would be a big bang.\n\nIt wouldn't do any serious damage to the planet's general structure though.",
"Lets assume our spaceship has a mass of about 80 tons, since that is about what the old space shuttle weighed. Let's also assume that our spaceship is only going at about 0.8 c, because I want to maintain some shred of realism. Using Einstein's formula for kinetic energy at reletivistic speeds: \nEk = m(c^2)*(((1/(sqrt(((c^2)/(v^2))-1) \nwhere m is mass,\nv is velocity,\nand c is the speed of light in a vacuum.\n\nSo the calculation is:\nEk = = (80 metric tons * c^2 ) * ( ((1/sqrt(((0.8*c)^2)/((c)^2)) -1)\nWhich according to wolfram alpha is about 1.8 * 10^21 Joules.\n\nTo put this in perspective, the largest atomic weapon ever detonated, the Tsar Bomba, had a yield of about 2.4 * 10^17 Joules.",
"An object cannot travel 'at' the speed of light, it can only be made travel at a speed arbitrarily close to the speed of light. This might seem pedantic but it's an important distinction.\n\nIn a sense, your question isn't very illustrative (I don't mean this as a put down, I'll explain what I mean), what does travelling near the speed of light mean? \n\nThe differences in energy between an object travelling at 99% the speed of light and 99.9% the speed of light is huge, far more than the 0.9% difference would belie. The difference between travelling at 99.9% and 99.99% the speed of light is far more enormous again.\n\nThe important thing here is the Lorentz factor.\n\nThe classical (Newtonian) definition of kinetic energy is E = 1/2 mv^2. This requires a relativistic correction when we travel near the speed of light.\n\nThe correct relativistic equation for kinetic energy is \n\nE = (gamma-1) * [mc^2 ] \n\nwhere gamma is 1/[1-v^2 / c^2 ]\n\nand where v is the velocity of the particle and c is the speed of light. (m is the mass of the particle in its rest frame, i.e. its rest energy). If you know how to do a Taylor expansion, then you can show that this gives the Newtonian formula for Kinetic energy for small v.\n\nSo if we look at this gamma factor, when v is very close to the speed of light, we can see in the denominator we have 1 minus something which is very close to 1, which is a very small number. so 1 over this is a very big number. The consequence of this: when we travel close to the speed of light, the kinetic energy becomes enormous, tending towards infinity as the speed tends to c. (Perhaps a better way to look at this is that it takes increasingly large amounts of effort to accelerate something close to the speed of light).\n\nSo perhaps a few examples here might be illustrative. Suppose our spaceship weights, for simplicity, 1kg.\n\nIf it is travelling at 50% the speed of light the Lorentz factor is roughly 1.33, so it would have (1.33 - 1)*(300000000^2) = 3 * 10^16 J, while the Newtonian definition gives 1.125 * 10^16 J, so the correct relativistic formula gives roughly 3 times more kinetic energy than the classical definition would imply in this case. So the Newtonian definition of kinetic energy is pretty wrong. Note that this is roughly the energy released in forming [meteor crater](_URL_0_), so we're already talking about unpleasant consequences.\n\nIf it is travelling at 90% the speed of light the Lorentz factor is roughly 5, i.e. it would have roughly 4 (gamma - 1 = 4) times more kinetic energy than the classical definition would imply. So the kinetic energy is 5 * 1/2 * (300000000^2), which is about 2 * 10^17 J, which is roughly the energy released by the [Tsar Bomba](_URL_1_), the largest nuclear weapon ever tested on earth, at 50 megatons.\n\nIf it is travelling at 99% the speed of light the Lorentz factor is roughly 50, so the kinetic energy is roughly 2*10^18 J, about 2 or 3 times the energy released by the eruption of [Krakatoa](_URL_3_) in 1883, which had widespread global climate effects even years later. At this stage, our tiny 1kg spaceship colliding with earth is starting to look like **very** bad news.\n\nIf it is travelling at 99.9% the speed of light the Lorentz factor is roughly 500, so the kinetic energy is about 2*10^19 J. This is roughly the amount of energy produced a year by the US. Clearly these energy scales aren't necessarily destructive if the energy doesn't go into an impact event.\n\nIf it is travelling at 99.99% the speed of light the Lorentz factor is roughly 5,000, so the kinetic energy is about 2*10^20 J. This is probably comparable to detonating the world's total nuclear arsenal at once.\n\nand if we skip a few,\n\nIf it is travelling at 99.99999% the speed of light the Lorentz factor is roughly 5,000,000, so the kinetic energy is about 2*10^23 J. This is the scale of the asteroid impact that created the [Chicxulub crater](_URL_2_) and probably caused a mass extinction event.\n\n(edited to fix the formula for kinetic energy according to comment below)"
]
}
|
[] |
[] |
[
[
"http://en.wikipedia.org/wiki/Space_Shuttle",
"http://en.wikipedia.org/wiki/Relativistic_kill_vehicle"
],
[],
[
"http://en.wikipedia.org/wiki/Meteor_Crater",
"http://en.wikipedia.org/wiki/Tsar_Bomba",
"http://en.wikipedia.org/wiki/Chicxulub_Crater",
"http://en.wikipedia.org/wiki/1883_eruption_of_Krakatoa"
]
] |
||
2s3xiy
|
if law enforcement aren't allowed to enter our homes without a warrant, why are they allowed in our yards?
|
I'm just curious. Are there different laws for land than there are for structures on the land? And if so, why? I started wondering after hearing about a man's dog being shot and killed by police (while he wasn't even home) after they jumped his fence while looking for a suspect. Thank you in advanced!
|
explainlikeimfive
|
http://www.reddit.com/r/explainlikeimfive/comments/2s3xiy/eli5_if_law_enforcement_arent_allowed_to_enter/
|
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" > after they jumped his fence while looking for a suspect\n\nThis is a key piece of information. If they had a reasonable suspicion that a suspect had entered your home, they could enter it without a warrant, too.\n\nThere are four instances where the police can search private property without a warrant:\n\n1. **Consent**: The property owner agrees to let them enter. \n2. **Plain View**: If the police see something illegal in plain view from a location where they already have a right to be, they can enter and search your home without a warrant. \n3. **Search Incident to Arrest**: If you're being arrested in your home, they can also search your home for weapons/people who might post a danger to them, and to prevent the destruction of evidence. \n4. **Exigent Circumstances**: This the the exclusion that is relevant to your story. If police are in hot pursuit of a suspect, and that suspect enters your property, they can enter your property (including your home) without a warrant in order to search for or apprehend the suspect.",
"They can enter you home or other property (warehouse, car, boat, trailer, etc) while in pursuit of a criminal if they have reasonable suspicion to believe that he's in there or passed through there."
]
}
|
[] |
[] |
[
[],
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|
e1olgf
|
Humans have been living side-by-side with cats for a very long time. What is the history behind litter boxes / designated bathroom areas for cats?
|
Do we have any early records of litter boxes or similar areas where cats would be trained / conditioned to relieve themselves?
|
AskHistorians
|
https://www.reddit.com/r/AskHistorians/comments/e1olgf/humans_have_been_living_sidebyside_with_cats_for/
|
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"I have a side-question: where did ships' cats go to the bathroom? Did the cats just ruin some corner of the orlop or what?",
"I know the thread is a month old, but someone just asked a similar question and I remembered this one sitting here (half the reason I had looked into the matter was because of this question, just hadn't had the time to write then), so better late than never for anyone still checking... but here is the response I wrote for that one.\n\n----------------------\n\nIf your cat was an indoor cat, you would likely provide them some sort of absorbent material. In the 1922 *Feeding and Care of the Domestic and Long-Haired Cat*, the following advice is offered:\n\n > Each room should also contain a fair sized granite pan, partly filled with sand or sawdust. I prefer saw dust as it does not hold moisture as long as sand and is free from fleas. \n\nSimilar advice was offered in the 1921 *Your Dog and Your Cat, How to Care for Them: A Treatise on the Care of the Dog and Cat in the Home*, with the author writing that:\n\n > A pan of sawdust, sand, or torn bits of paper should be kept in some convenient place for their use in attending to their functions. They must have free access to this if they are to be clean with their habits.\n\nLikewise, the 1889 *Our Cats and All About Them* reminds readers that:\n\n > Always have a box with dry earth near the cat's sleeping place, unless there is an opening for egress near.\n\nI do find amusing how much the authors of these old manuals strive to *avoid* directly stating what these are for. It is clear enough, of course, but the language is still euphemistic, speaking of 'their functions' and 'moisture'. Vague allusions to the 'cleanliness' of the cat are common too, such as the 1895 guide which notes:\n\n > The cat is an excessively cleanly animal, and when housed should be provided with means for remaining so. A small box, or -- what is better, as it can be well washed -- a galvanized flat pan such as used for roasting meat, should be placed in some well-ventilated corner out of sight, and kept filled about an inch deep with sand, clean earth, or sawdust. Perhaps the latter is preferable, as it can be burned. The litter should be changed frequently.\n\nAlso going on to note that for kittens, a bed of peat-moss litter has the \"desired effect\" of teaching them cleanliness, when changed at least once a day.\n\nWhile hardly a scientific survey of the literature, only a single book, 1887's *The Cat* made reference to actual product in noting that the creature is \"*guided by a peculiar instinct to scratch up earth for the purpose of hiding their excrements*\" and that indoors even will do their best to avoid the carpet, \"resort[ing] to cinders or coal-dust\"*. They go on to note similar ways to accomodate this as others did, writing that:\n\n > It is a good plan to have a large flower-pot saucer - the larger the better, but not less than fifteen inches in diameter - kept in some suitable corner, with a little clean garden-earth or sand in it. It need not contain much earth and it can be changed at will; but should not be allowed to become foul as to offend the cat.\n\nWriting advice for owners of \"catteries\", that is, breeders with large collections of cats, the most practical advice in 1901 *Domestic and Fancy Cats* is simply that:\n\n > Sanitary arrangements in these catteries are not so difficult, for the free access to the outside runs, if cats have been trained to habits of cleanliness, will be readily sought for and discovered by them.\n\nBut recognizing this isn't always possible, the author continues:\n\n > Still it may be desirable to provide receptacles, and I know of no better than the large stoneware pans supplied by Spratts Patent, or zinc trays can be mate whatever size and shape is desired. Opinion varies as to what these are to be filled with. I have from the earliest period, and down to date, been an advocate of dry earth; some however consider sawdust as far and away the best, and only a few years ago I was informed by a large breeder that if earth and sawdust be placed in separate receptacles, sawdust will be selected by the cat. Be this as it may, I am still open to conviction of is efficacy, over Nature's deodorizer. An efficient deodorizer or disinfectant should always be kept at hand, such as Izal, Sanitas, Jeyes', or Lawes', which rank above most others. \n\nGoing back further into the 19th century, there is even stronger emphasis on the *cleanliness* of the cat, with an author in the 1870s writing that:\n\n > Cats of the right sort never fail to bring their kittens up in the way they should go, and soon succeed in teaching them all they know themselves. They will bring in living mice for them, and always take more pride in the best warrior-kitten than in the others. They will also inculcate the doctrine of cleanliness in their kits, so that the carpet shall never be wet. I have often been amused at seeing my own cat bringing kitten after kitten to the sand-box, and showing it how to use it, in action explaining to them what it was there for. When a little older, she entices them out to the garden.\n\nOf course, they later go on too note that a cat will *literally die* if they get too dirty, writing:\n\n > I have known cats take ill and die from having their coats accidentally soiled beyond remedy.\n\nThis might be a bit excessive, but this emphasis on the 'instinctive cleanliness', as countless guides in the late 19th to early 20th century noted, was the \"natural virtue which renders pussy so generally a favoured intimate of the household\".\n\nSo the sum of it is that there was no one solution offered, but there was certainly a general consensus on the necessity of providing an indoor place for relief, and while the advice varied as to the specific material, be it sawdust, earth, or otherwise, it ought be something absorbent and changed frequently.\n\n**Sources**\n\n*Feeding and Care of the Domestic and Long-Haired Cat* by Ellen V. Celty and Anna Ray\n\n*Your Dog and Your Cat, How to Care for Them: A Treatise on the Care of the Dog and Cat in the Home* by Roy Henry Spaulding\n\n*The Cat, A Guide to the Classification and Varieties of Cats and a Short Treaties Upon Their Care, Diseases, and Treatment* by Rush Shippen Huidekoper\n\n*Domestic and Fancy Cats: A Practical Treatise on Their Varieties, Breeding, Management and Diseases* by John Jennings\n\n*Cats: Their Points and Characteristics, with Curiosities of Cat Life, and a Chapter on Feline Ailments*\n\n*Our Cats and All About Them: Their Varieties, Habits, and Management, and for Show, the Standard of Excellence and Beauty* by Harrison Weir\n\n*The Cat: Its Natural History; Domestic Varieties; Management and Treatment* by Philip M. Rule\n\nThis is just a sampling of texts out there, but you can find them and more on _URL_0_, HathiTrust, and Project Gutenberg.\n\nAfterward: Looking through a lot of old books about cats and trying to find more references, I had to share one false positive hit for \"sawdust\" which ended up being about a ship's cat:\n\n > Tuesday was flogging day; and to add, if possible, to the terror of the condemned wretch, after the gratings were rigged and the man stripped and lashed thereto, sawdust was sprinkled on the deck all round, to soak up the blood. But at every flogging match\n\n > > “There sat auld Nick in shape o’ beast,”\n\n > at least in the shape of Tom the cat, who would not have missed the fun for all the world. There on the bulwark he would sit, his eyes gleaming with satisfaction, his mouth squared, and his beard all a-bristle. He seemed to count every dull thud of his nine-tailed namesake, and emitted short sharp mews of joy when, towards the middle of the third dozen, the blood began to trickle and get sprinkled about on sheet and shroud. Though I never disliked Tom, still, at times such as these, I really believed he was the devil himself as reputed, and would have given two months’ pay for a chance to brain him. When the flogging was over, Tom used to jump down and, purring loudly, rub his head against his master’s leg.\n\nTom seems like *kind of a dick*."
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3s2vv3
|
equations and inequalities with absolute value.
|
explainlikeimfive
|
https://www.reddit.com/r/explainlikeimfive/comments/3s2vv3/eli5_equations_and_inequalities_with_absolute/
|
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89lb6r
|
If someone becomes immunized, and you receive their blood, do you then become immunized?
|
Say I receive the yellow fever vaccine and have enough time to develop antibodies (Ab) to the antigens there-within. Then later, my friend, who happens to be the exact same blood type, is in a car accident and receives 2 units of my donated blood.
Would they then inherit my Ab to defend themselves against yellow fever? Or does their immune system immediately kill off my antibodies?
(Or does donated blood have Ab filtered out somehow and I am ignorant of the process?)
If they do inherit my antibodies, is this just a temporary effect as they don't have the memory B cells to continue producing the antibodies for themselves? Or do the B cells learn and my friend is super cool and avoided the yellow fever vaccine shortage?
EDIT: Holy shnikies! Thanks for all your responses and the time you put in! I enjoyed reading all the reasoning.
Also, thanks for the gold, friend. Next time I donate temporary passive immunity from standard diseases in a blood donation, it'll be in your name of "kind stranger".
|
askscience
|
https://www.reddit.com/r/askscience/comments/89lb6r/if_someone_becomes_immunized_and_you_receive/
|
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"I have only read about this particular situation in terms of embryology. In Langman's Medical Embryology, it states that a mother is able to pass through fluids, antibodies to the product whether by virtue of colostrum during infancy or even direct blood transfusion down the line. This is a practical example of what you are asking about where it would function exactly as you say.\n\nAntibodies specifically, are very small markers which serve the function of being an encumbrance (Immediate identification of colonization threat to general macrophages, metabolic interference of the colonizing agent, obstruction of their receptors, etc.) to specific antigen through a process of adsorption, the following statement makes me wonder if you were told antibodies directly \"fought\" infections :\n\n > Would they then inherit my Ab to defend themselves against yellow fever?\n\nSo there's that consideration, but anyway, I hope I was able to help in some way.",
"So for blood transfusions used in trauma, ~~the patient will receive what's called \"Washed\" blood, which is donated blood which has had its plasma components removed. This includes antibodies and another set of immunological proteins called complement proteins. So no, he wouldn't receive any antibodies in a normal situation.~~my apologies, I just glanced over some lecture materials and misinterpreted a slide, my mistake.\n\nHowever, I'm sure you're still interested in knowing what would happen and I'm happy to answer this. Transfusion of antibodies is already a medical technique called Intravenous Immunoglobulin transfusion. These are used for patients that unfortunately suffer from immune system disorders so they have diminished or absent immune response. These donated antibodies from vaccinated patients have the ability to bind to pathogens through their F-ab component while still being able to bind to F-c Receptors of immune cells by the F-c components. However, to answer your question, this would only be a transient protection and patients that need this procedure need them consistently.\n\nThe reasoning for this is because B cells, the immune cells that produce the antibodies, have no process by which they could receive immunity from someone else's antibodies. Your B cells have to undergo a selection process in your bone marrow, like your T cells in your thymus. As a small background, your B cells provide practically all encompassing antigen binding because they undergo a controlled, mutagenic arms race in their selection process in order to be let out of the bone marrow. Once they're out of the bone marrow after successful selection, they have their own unique antigen binding trait and this would not be changed by the introduction of someone else's antibodies. The binding affinity of the antibody a B cell does change over time, however, once it encounters its match made in heaven antigen, it'll reignite its microbiological Cold War Era arms race in a process called somatic hypermutation to produce an improved antibody.\n\ntl;dr Your antibodies would only give a temporary immunity because there's no process that they could influence their own synthesis in your friend",
"If someone is producing antibodies for a specific receptor, those antibodies will bind its respective receptor. This is actually used to treat some diseases. Most notably, it is the only way (correct me if I am wrong) we have to treat people who were bit by a venomous animal. For example, non-lethal amounts of said venom are administered to animals (ex. a horse). The horse will then produce antibodies for the venom which are harvested and used to treat patients who were bit by venomous animals and the antibodies will neutralize the venom. \n\nHowever - it is important to note that simply transferring antibodies to a patient does not immunize them against a pathogen or foreign antigen per se. In order for that to occur, you need to present the antigen you want to protect against to the immune system (i.e. that's why vaccines use actual virus particles), which will then go through the process of T cell/B cell activation and possibly result in memory cells which are capable of producing antibodies against the foreign particle for a relatively long time. Repeated exposure to the antigen is needed in order to maintain antibody production in some cases, but now we're getting a bit too complicated for the purpose of the question. \n\nCirculating antibodies can remain in your system for many years, but will likely disappear after x amount of time if the antigen isn't present.\n\nTo answer your question directly: if the yellow fever Abs were in your blood, they would neutralize yellow fever virus particles in another person, but the other person would not actively produce yellow fever Abs (we need antigen recognition/processing for this to occur). ",
"While all of the other comments have mentioned active and passive immunization etc. There is a way that you can become immunised against something sort of by recieving their blood. One case is The Berlin Patient, who became immune to HIV after a bone marrow transplant. In short, he had HIV and then subsequently leukaemia and underwent a bone marrow transplant and his HIV levels dropped. This was because the new leukocytes being produced had a mutation in the CCR5 receptor (originally in the genome of the donor) meaning that the HIV couldn't enter his CD24 cells. So in short you can indirectly become immunised by receiving someone else's 'blood'.",
"Nope, imagine your lymph nodes as little castles where the B cells live. In your case some of these B cells are already trained to fight off yellow fever. When you get infected with yellow fever again dendritic cells carry pieces of the pathogen to the castles and activate the B cells. The B cells then make the antibodies which are like tiny heat seeking missiles that target the specific pathogen. Unless you give your buddy large quantities of trained B-cells which we can't really do, you can't give him immunity. We can give the antibodies produced by B-cells or synthetic antibodies against the antigen though. ",
"In this situation no... When blood is donated its separated into it's components: red cell, plasma, and platlets. All your antibodies are in your plasma. And 2 units is not nearly enough. But what you are asking about is called a therapeutic plasma exchange. A machine pumps ur blood out goes through machine spins it down takes only the plasma out and then the donor plasma is then put back in your system( 2000-3000mls) for an adult. This process is used to treat the flu along with a host of other things. Doesn't last long few months or so it's called passive immunization. Source: me transfusion specialist ",
"On a slight tangent, if you do not have time to get immunized for say Hepatitis A before a trip to someplace that you will need it, you can get an injection of immunoglobulin (antibodies) aka gamma globulin which will give you passive (temporary) immunity. As discussed above it will \"wear off\" and as the antibodies are cleared by your body, your own B-cells will not make more.",
"Immunized plasma is a thing. For example there is a study being conducted by the NIH evaluating the effect of transfusing plasma donated by people with strong immunity against Influenza A to people struggling to fight the flu. Similarly, it’s the same principle used to treat Ebola. ",
"In short: no.\n\nLonger less direct answer: Immunity is transferred from donor to recipient in bone marrow or peripheral blood stem cell transplant. In these the donor immune system is destroyed by radiation, and replaced by the donor's through the transplant.\n\nIn these situations, the recipient gets the donor's immunities, and even allergies.\n\nSource: am a PBSC donor",
"One of the goals of immunization is to stimulate an acquired immune response as soon as you get an infection. Part of that response is your central memory T-cells and Long Lived Plasma B-cells. Those cells live in the lymph nodes, so they wouldn’t be acquired in a whole blood transfusion.\n\nAnother part is your effector memory T-cells and long-lived MEMORY B-cells. Those do circulate. So, if you did find a case where there is a whole blood transfusion, those would transfer. However, those cells are second line responses. Their purpose is to clear pathogens so fast you don’t need any other response. So it’s not the ideal type of immunity.\n\nThat’s not to mention that most blood transfusion isn’t whole blood. It’s mostly RBCs to avoid transfusion reactions.",
"they will potentially receive transient protection but it is quite possible that their body could develop its own immune response to any component of the transferred antibodies. the antibodies exist in serum specifically, so whole blood will also contain them unless it is filtered out (i don't know how blood is processed for transfusing). this is the basic premise of antiserum... horses are injected with small amounts of an antigen like a toxin and they produce a neutralizing antibody response to the toxin. the animal is phlebotomized and serum is separated to isolate these neutralizing antibodies so that they can be injected into a recipient to counteract the same toxin. the blood type wouldn't really matter as much because blood type is determined by RBC surface antigens and the antibodies are not associated with the RBC, however it is possible that immune reactivity with non-matching RBC antigens could serve as an adjuvant inducing inflammation that may make reactivity to other components of the transfusion more likely.\ne: their b-cells will not learn to produce antibodies of the same specificity as your antibodies (that is, against the virus or bacteria you're hoping to be immunized against). neutralizing antibodies transferred via serum only provide temporary protection. you need your own immune response to do that.",
"The person that was immunized would develop a full response (T cells, B cells, the whole ordeal). They would then have long lasting immunity specific to the antigen they were exposed to. This long lasting immunity is an outcome of memory, a subject that is still not well understood in immunology. \n\nTransfusing blood between individuals will cause passive immunity. This is momentary and will fade. Antibodies are just proteins, and as any protein, they are turned over. They will be turn over at a slower rate however, and may stay in circulation for about a month. Once they are gone, so will that immunity.\n\nYour immune system would not really have any problem with the transfused antibodies, as long as they are human. If they come from any other species, you will develop an immune response to those antibodies.\n\nThere are cases were transfusion of antibodies leads to development of memory, but those are more towards immunotherapies towards cancer. If you are interested, I can provide an overview about it.",
"Some diseases are treated by infusing the patient with antibodies purified from the blood of an animal that had been infected. The so-called 'antiserum' (or \"IgG Fraction\") has sufficient antibodies to reduce the number of infectious agents in the patient, giving them a chance to recover. I think the treatment for rabies consists of both vaccination and a series of antiserum injections.\n\nAt one time, this was such a breakthrough treatment method that the term \"serum\" was nearly synonymous with \"medicine\". Hence, we have such terms as \"truth serum\", when referring to a cocktail of drugs that reduce mental alertness in the subject of an interrogation.",
"A single patient, known as the Berlin Patient, was cured of HIV with a bone marrow transplant. \n\n_URL_0_\n\nHowever, two subsequent HIV positive patients, called the Boston patients, who were believed to have been cured with bone marrow transplants have since relapsed.\nI understand that the Berlin patient received a bone marrow donation that was naturally resistant to HIV (a very small segment of the population is) while the Boston patients could not find a matching bone marrow donor who was also HIV resistant. \nViruses are full of tricks.\n",
"Short answer: No.\n\nSlightly longer answer: Maybe temporarily.\n\nLonger answer:\n\nImmunization requires your body to make a long-term adaptive response that will then protect you against the immunogen. Simply transferring blood will not provide you long-term protection and is not analogous to an immunization. As a caveat to this, you can get temporary, passive humoral immunity through the transfer of immunoglobulin. This protection will be temporary at best and may be imperfect. It will only work via the humoral immune system and it will wane as the half-life of the protective antibodies transferred by the serum is only 14-21 days.",
"Yes and no. Yes, because you will have antibodies that will protect you for a short period of time, but it will wear off pretty quickly. This is because YOU are not making the antibodies. There are specific cells (B cells) that secrete antibodies. These cells and their differentiated formd stay in lymph nodes (and other secondary lymphatic organs)/bone marrow.\n\nInterestingly, the use of antibody transplant has actually been tested. I'm pretty sure it was used on some infected medical personnel during the Ebola crisis. ",
"In immunohematology I don't think this is a possibility for any blood product (there are multiple), and the memory cells or other wbc would not live long enough or be in high concentration (same idea with giving someone O- whole blood, not enough cells to cause significant hemolysis). Buut, my question is would you get cells that are presenting immunity? ",
"Yes and no.\n\nAntivenom is basically what you're talking about. You inject the animal with venom, the animal makes antibodies against the venom, then you collect and process the blood into serum.\n\nJust like antivenom wouldn't make you permananty immune to snake bites, an antibody transfer would also be temporary.\n\nNow the reason this wouldn't really work is that your resting antibody titer against yellow fever after you get well will be minimal, there wouldn't be nearly enough to be protective, especially as dilute as in whole blood.\n\nIf they drew blood right at the height of the fever, purified out and concentrated the antibodies, that might get them enough material to dose someone with and grant temporary protection.\n\nThe DoD actually does this pretty regularly against potential biological agents/weapons, they inject healthy volunteers with an antigen thats basically a mock-up of the agent multiple times over a schedule to generate a large antibody response, and collect the blood to purify out the antibodies. "
]
}
|
[] |
[] |
[
[],
[],
[],
[],
[],
[],
[],
[],
[],
[],
[],
[],
[],
[
"https://www.nature.com/news/2009/090211/full/news.2009.93.html"
],
[],
[],
[],
[]
] |
|
krzc8
|
If homosexuality is completely genetic, and it became a worldwide social norm, would it eventually die out from lack of passing the gene on?
|
Let's say that hypothetically no homosexuals ever reproduced again.
|
askscience
|
http://www.reddit.com/r/askscience/comments/krzc8/if_homosexuality_is_completely_genetic_and_it/
|
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"text": [
"For a lot of reasons: no.\n\nedit: adding reasons\n\nLet's assume that homosexuality is a binary thing and 100% genetic.\n\nSomeone not having the homosexual phenotype doesn't mean he doesn't have the genotype.\n\nParents not expressing the phenotype may still generate children who do.\n\nAlso there have been some suggestions that homosexuality has benefits to groups and while that is the case, the gene will have a reason to procreate. (the benefit doesn't have to apply to the individual, it's enough when it applies to a group, lookup \"Altruism in Evolution\").",
"Just to get this out of the way, being \"born that way\" doesn't always mean it's genetic. A lot happens in the womb that shapes who you'll eventually be. Even the non-genetic contents of a fertilized egg can be considered \"environment\".\n\nNow, something being \"genetic\" doesn't mean there's one gene that causes it (and does nothing else). There are hundreds or thousands of genes that contribute to your overall personality and sexual disposition. Even if you are born gay, never reproduce, doesn't mean those same genes aren't out there in many other people getting passes along just fine.\n",
"For a lot of reasons: no.\n\nedit: adding reasons\n\nLet's assume that homosexuality is a binary thing and 100% genetic.\n\nSomeone not having the homosexual phenotype doesn't mean he doesn't have the genotype.\n\nParents not expressing the phenotype may still generate children who do.\n\nAlso there have been some suggestions that homosexuality has benefits to groups and while that is the case, the gene will have a reason to procreate. (the benefit doesn't have to apply to the individual, it's enough when it applies to a group, lookup \"Altruism in Evolution\").",
"Just to get this out of the way, being \"born that way\" doesn't always mean it's genetic. A lot happens in the womb that shapes who you'll eventually be. Even the non-genetic contents of a fertilized egg can be considered \"environment\".\n\nNow, something being \"genetic\" doesn't mean there's one gene that causes it (and does nothing else). There are hundreds or thousands of genes that contribute to your overall personality and sexual disposition. Even if you are born gay, never reproduce, doesn't mean those same genes aren't out there in many other people getting passes along just fine.\n"
]
}
|
[] |
[] |
[
[],
[],
[],
[]
] |
|
2pj0pd
|
Jefferson and Hamilton: When did the debate or our politics shift?
|
I am reading Jefferson and Hamilton by John Ferling, and in the preface, Ferling notes that modern republicans have favored the fiscally responsible Hamilton, while democrats favored the individual liberty rhetoric of Jefferson. Most interestingly, Hamilton was a federalist (strong government), but Jefferson was a democrat-republican that wanted to stay away from anything resembling centralized powers.
When did Hamiltonian *strong federal government and fiscal responsibility* become Reaganomic *strong states and fiscal responsibility*? From a modern point of view, it seems weird that Reagan and Bush would praise a man who wanted a strong federal government. Likewise, it is weird that Clinton would praise a man who envisioned a confederacy.
|
AskHistorians
|
http://www.reddit.com/r/AskHistorians/comments/2pj0pd/jefferson_and_hamilton_when_did_the_debate_or_our/
|
{
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"There are lots of dry scholarly articles out there if you want to look, but [here's an easy-to-read piece](_URL_1_) from [Eric Rauchway](_URL_3_), who I find to be a very respectable guy without the airiness of some of the other writers.\n\nTo summarize, the shift really started in the 1896 election, when the Democrats fused with the [Populists](_URL_2_) and William Jennings Bryan and his [Free Silver](_URL_4_) platform won the Democratic nomination, going against the pro-business [Bourbon Democrat](_URL_0_) tradition that Grover Cleveland, the incumbent, had pursued. The party lost in a landslide to William McKinley, but it started an era, spanning until at least the mid-20s, in which the party lines blurred. When the Democrats, led by Woodrow Wilson, finally regained a Congressional majority in 1913, they passed several key pieces of legislation based on Bryan's ideals, including the Federal Reserve Act and the income tax. Congressional Republicans first started taking the small government stance in the 20s, and by 1936, FDR had been elected to his second term as a Democrat and the Republicans were voting against the New Deal.",
"I'd be really interested to read this preface. I feel like this has less to do with party alignment and more to do with how these issues have changed over time. Example, a strong central bank was preferred by merchants and business. \n\nAs an aside, and maybe Ferling will prove me wrong, I'm almost never a fan of these type of comparisons. Investment banking/the financial sector wasn't a thing until the Civil War in America, Keynes didn't publish until 1936, and neoliberalism developed decades after that. So much has change I don't see how anyone can make a claim that \"x\" group or \"x\" party would have identified with \"x\" historical figure without it being very careful throughout and planned."
]
}
|
[] |
[] |
[
[
"http://en.wikipedia.org/wiki/Bourbon_Democrat",
"http://chronicle.com/blognetwork/edgeofthewest/2010/05/20/when-and-to-an-extent-why-did-the-parties-switch-places/",
"http://en.wikipedia.org/wiki/People%27s_Party_%28United_States%29",
"http://en.wikipedia.org/wiki/Eric_Rauchway",
"http://en.wikipedia.org/wiki/Free_silver"
],
[]
] |
|
fjc8y8
|
Is the development of the modern clown (clumsy, big lips) related at all to racial stereotyping/minstrel shows?
|
AskHistorians
|
https://www.reddit.com/r/AskHistorians/comments/fjc8y8/is_the_development_of_the_modern_clown_clumsy_big/
|
{
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"text": [
"The classic clown makeup- white face, huge red lips, lined eyebrows- predates the rise of minstrel shows in the 1830's. It originated with [Joseph Grimaldi](_URL_0_) ( 1778-1837). There are various explanations ( one is that it imitated the face of a greedy child who's been gorging himself on jam tarts) but the contrasting colors meant that Grimaldi's facial expressions could be seen quite well in the theater lighting of the time, which was much dimmer than today ( the bright limelights of the Victorian theater were invented the year of his death).\n\nGrimaldi was immensely popular. He really originated the character of the clown that would be a stock character in English pantomimes ( or \"Pantos\") , and whiteface clowns are still called \"Joeys\". But in an age before mass media, the only way he could make money on that popularity was to perform, over and over. Sometimes he would do two shows a night, in two different theaters. Those performances were hard work, required him to throw himself around quite a lot. He also had significant expenses- a country house, a wife who liked nice things, a private school for his son. Bankruptcy was constantly a threat. Not surprisingly, by the 1820's he was in very bad shape, self medicating with alcohol, and unable to work.\n\nThe costumes and makeup of minstrel shows of the 1800's and later were likely affected by Grimaldi 's character of the clown.. Dan \"Daddy\" Rice not only performed as a circus clown but worked in blackface, and it's hard to miss the similarities: clowns and blackface minstrels were both supposed to be, essentially, gleeful uninhibited children. In the case of the minstrel shows, of course, portraying African Americans as happy children served the useful purpose of making acceptable their domination by white people.\n\nJohn H Towsen : Clowns"
]
}
|
[] |
[] |
[
[
"https://en.wikipedia.org/wiki/Joseph_Grimaldi#/media/File:Grimaldi_and_Vegetable.jpg"
]
] |
||
2r67no
|
why do i absolutely hate things that become popular, things which i may have once liked, for seemingly no reason?
|
explainlikeimfive
|
http://www.reddit.com/r/explainlikeimfive/comments/2r67no/eli5_why_do_i_absolutely_hate_things_that_become/
|
{
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"cncvnen"
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"Often things that are popular only get discussed in a positive light and any flaws with it tend to be overlooked by the masses in general. This can lead to the dissenter to focus on the negatives to justify their viewpoint to themselves and others making the thing in question seem worse than it is. \n\nAlternatively mass popularity tends to lead to over saturation of something to the point where you just instinctively get tired of it regardless of whether you like it or not.\n\nThe best way to overcome this is to simply watch it yourself and make your own judgments outside your own bias and the bias others try to force on you. Remember that very few things live up to hype and not everyone is going to have the same taste.\n\nIf you don't like something either simply avoid it or use non-hostile language when discussing it. \"It wasn't for me\" gets a lot less of an angry reaction from people than insulting them by claiming something they like is stupid."
]
}
|
[] |
[] |
[
[]
] |
||
2jh8lf
|
how do you start a fire by blowing on it? shouldn't that put it out?
|
explainlikeimfive
|
http://www.reddit.com/r/explainlikeimfive/comments/2jh8lf/eli5_how_do_you_start_a_fire_by_blowing_on_it/
|
{
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"text": [
"Blowing on a fire, or more usually the embers to start it brings the oxygen that fire can use as fuel closer to it, which allows it to grow and burn more.\n\nThis does only work to a certain degree though, if you blow too much air, or too hard at the fire, it'll blow it out if the fire's small enough; like when you blow out a candle."
]
}
|
[] |
[] |
[
[]
] |
||
19ow0n
|
why do the hours of daylight in a year not correspond strictly to latitude?
|
Is it because of topography?
|
explainlikeimfive
|
http://www.reddit.com/r/explainlikeimfive/comments/19ow0n/why_do_the_hours_of_daylight_in_a_year_not/
|
{
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"text": [
"An [image ](_URL_0_) detailing number of daylight hours in North America and Europe.\n",
"[Technically, it does](_URL_0_). But yes, topography does make a difference as well. However, these maps are measured with a device that measures sunshine (called a [Campbell-Stokes sunshine recorder](_URL_1_)). However, this is impacted by factors like cloud cover. As a result, places that experience clouds would have more sunlight. Depending on the location, seasons may also have an impact for the same reason.\n\n[This Australian map may also be of interest](_URL_2_)."
]
}
|
[] |
[] |
[
[
"http://imgur.com/tPueXaT"
],
[
"http://en.wikipedia.org/wiki/Day_length",
"http://en.wikipedia.org/wiki/Campbell-Stokes_sunshine_recorder",
"http://www.bom.gov.au/jsp/ncc/climate_averages/sunshine-hours/index.jsp"
]
] |
|
1g044x
|
Can fish become "overweight" from eating too much? Do they generate mass like an overeating human would or does their body size just keep growing until a certain set point as they eat larger proportions?
|
I thought of this while feeding my tropical tetra fish today. I can't say that I've ever seen a fat fish but then again I don't think I would know it if I saw it.
I know there are are freshwater fish as well as tropical... do they differ on this topic? Any insight would be appreciated.
|
askscience
|
http://www.reddit.com/r/askscience/comments/1g044x/can_fish_become_overweight_from_eating_too_much/
|
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"text": [
"I know this thread is *positively ancient* by internet standards, but I found an article that features a fish biologist who is [dissecting an obese lionfish!](_URL_0_)\n\nNow granted it's an invasive species so it's not exactly the \"normal\" case, but this does provide the best evidence I've seen that fish can indeed become overweight/obese!",
"I'm not a fish biologist (I'm a microbiologist!), but I did teach an intro bio course so I think I can provide a suitable answer. Fish are interesting and somewhat unusual amongst vertebrates in that their growth is [indeterminate](_URL_0_) (disclaimer: not true for *all* fish). This means that as long as they don't get eaten, get sick, or die some other way, they can essentially keep growing and getting larger indefinitely. This is in contrast to determinate growth, where the limit is genetically predetermined at some maximum size, as in humans and all other mammals. I found [this paper](_URL_1_) which has a paywall, but the relevant quote here is:\n > Fish growth is, like that of many plants, essentially indeterminate.\n\nIt's worth noting that this growth is asymptotic, which means that once it reaches \"adult\" size its growth slows considerably. However unlike adults of animals with determinate growth, they do still keep growing! It would be like a human growing to 6'0\" at age 20, but by age 50 they're 6'6\", and by 70 they're 6'10\" (or something like that).",
"Fish experience indeterminate growth, meaning they continue to grow (lengthwise) as long as conditions are appropriate. Fish growth is frequently modeled by a [Von Bertalanffy growth curve](_URL_0_) with growth eventually becoming asymptotic. However, fish of the same species in different systems may have different growth (i.e. bass in different ponds have different nutrients, space, and competition so growth may be different between ponds). In natural systems, limited resources usually mean that fish put growth on lengthwise, rather than becoming \"fatter\".\n\nYour question is regarding fish in an aquarium. The amount of space available in an aquarium will likely be the limiting agent for the length of the fish you are raising. For example, gold fish in a 10 gallon vs a 30 gallon tank are significantly different in size at the same ages even when all other resources are the same. Well-fed (nutrient rich) fish in a contained space can put on more muscle mass than their wild counterparts.",
"Yes, fish can get fat. \n\nUnder natural conditions fish only eat when they need to and food is available, which is why you don't see fat fish, not because of indeterminate growth. However, fish in a controlled systems, such as aquariums and hatcheries, are a little different.\n\nImproperly fed fish can and do get fat. Typically they store fat around internal organs, along their lateral line, and between myomeres. Just like in mammals, the excess fat affects the fishs' heath, survivability (on fish released into the wild), and flavor (commercial fish). ",
"Ok, we've had a lot of discussion about indeterminate and determinate growth, but I've realized that perhaps a better answer to the question of fish weight (rather than fish length) is answered in a discussion of the way a fish's fat is stored.\n\nFish, being exotherms (or more specifically poikilotherms) must keep fat deposits unsaturated (remaining fluid). Saturated fats solidify at cool temperatures, and fish (even those tropicals in your aquariums) had to develop a different way to store fat, keeping it flexible even at low temperatures. Thus, the way a fish stores fat is different from the way a cow, cat, or human store fat. \n\nFish fat is stored as fish oil, which effects their flavor. In particular, salmon store fat for their spawning migration. Anecdotally, Copper River salmon are more expensive because they store more fat than other spawning runs (they're prepared for a more difficult migration than other salmon).\n\nYes, a fish can and will store fat. The way the food is processed may change with increased feedings, but fish do not typically stop eating if they are 'full' (fish are accustomed to resource poor conditions). In the 'feast or famine' scenario of the wild, fish have [excess digestive capacity](_URL_0_), in situations (possibly your home aquarium?) with abundant food availability they may excrete nearly undigested food in addition to storing fat."
]
}
|
[] |
[] |
[
[
"http://www.slate.com/articles/health_and_science/science/2013/07/lionfish_invasion_the_invasive_fish_are_eating_so_many_native_species_that.html"
],
[
"http://en.wikipedia.org/wiki/Indeterminate_growth",
"http://www.annualreviews.org/doi/pdf/10.1146/annurev.es.18.110187.002103"
],
[
"http://www.fao.org/docrep/w5449e/w5449e05.htm"
],
[],
[
"http://www.nature.com/nature/journal/v476/n7358/full/nature10240.html?WT.ec_id=NATURE-20110804"
]
] |
|
1q6s7e
|
elim: why oil prices went up in 2000 even though opec's supply remained relatively high
|
So I was reading the OPEC wiki page (_URL_0_) and it states that "In the 2000s, a combination of factors pushed up oil prices even as supply remained high." What were those factors and why do oil prices stray from a standard Supply/Demand model?
|
explainlikeimfive
|
http://www.reddit.com/r/explainlikeimfive/comments/1q6s7e/elim_why_oil_prices_went_up_in_2000_even_though/
|
{
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"text": [
"Demand increased dramatically, basically. China and India saw huge increases in the number of people driving. China, for instance, had 20 cars per 1,000 people in 2004. By 2009, that was 47 cars per 1,000 people -- more than double the 2004 number in just 5 years. [Source](_URL_0_). That means a huge spike in demand for gas. So even while supply remained high (largely stagnant, but high) demand vastly increased. Thus, oil prices didn't stray from the supply/demand model; demand increased, driving up prices.\n\nThere's a lot of other stuff, particularly dealing with the change in the value of the dollar caused by the economic collapse of 2008-09, but the reason prices have remained so high is just increased demand."
]
}
|
[] |
[
"http://en.m.wikipedia.org/wiki/OPEC"
] |
[
[
"http://data.worldbank.org/indicator/IS.VEH.NVEH.P3"
]
] |
|
46fna2
|
Does Earth have the most varied elemental composition in the solar system?
|
On the surface, Earth looks like a very diverse planet compared to the monotone wastelands of the other planets. However, I wonder if this translates to actual elemental diversity, I.e. a relatively high standard deviation of atomic number.
|
askscience
|
https://www.reddit.com/r/askscience/comments/46fna2/does_earth_have_the_most_varied_elemental/
|
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"text": [
"Well, if you just mean total number of elements, we win. Every known natural element can be found on earth, and we have synthesized some, so we have more than any other planet could ever have. \n\nNow most of these synthesized ones have a half life of less than one second, so we don't have them now, but we have made them before.",
"If you don't count man-made elements, Earth is pretty typical for the inner planets in our solar system when it comes to abundance of elements. \n\nDuring the birth of the Solar System, the orbits of the inner planets was too warm for *volatile* molecules like water and methane to condense. Thus, Venus, Earth Mars etc have a lot more compounds with high melting points, such as metals and rocky silicates, since these compounds clumped together during accretion while the volatile compounds continued to float around until the were captured by the high gravity planets forming in the outer solar system. \n\nThe terrain looks diverse because earth's gravity is strong enough to keep an atmosphere, and the temperature is *just right* for water in the atmosphere to be liquid some of the time. This liquid water forms oceans, causes erosion, and makes it possible for life to form. Those oceans, erosions and life is what provides the zest or color to our landscapes.\n\nFor a look at what the elements in earth would look like without water or an atmosphere, just look at the moon. It's a monotone wasteland with pretty much the exact same elemental abundance as the earth.",
"The [paper](_URL_0_) estimates that Venus should be slightly more diverse than the Earth, although the authors stress that they can only model most of the chemical abundances. The Earth has a bit more of the common elements iron and nickel, but Venus is enriched in most of the rare elements.",
"I'm an engineer, not a planetary scientist, but I'd venture to say no. The earth formed from the same accretion disk and collection of dust that formed the sun and all the other planets, moon, and so forth. Jupiter and Saturn, Neptune and Uranus, for example, have more hydrogen and helium gas than the earth, but that's only because their greater gravity allows it to hold on to these elements in its atmosphere. Similary, Mars has much less of an atmosphere than Earth, mostly cause its gravity can't hold it. But Venus is roughly the same size as Earth, so why is its atmosphere so much thicker? Well, if the Earth were similarly hot, and all the water on the Earth were to evaporate (without escaping into space), the pressure on the surface would be about 250 times the pressure at sea level, and more than twice the pressure on the surface of Venus.\n\nAll that is to say that there's nothing special about the elemental composition of the earth. We have all the same elements as other planetary bodies in our solar system, just the *proportion* of these elements are different. "
]
}
|
[] |
[] |
[
[],
[],
[
"http://www.pnas.org/content/77/12/6973.long"
],
[]
] |
|
2ld9vd
|
Sup everyone! I was wondering about terminal velocity. How exactly do you calculate it, and how do you determine how long it would take for an object to reach it?
|
Bonus question is why exactly there is a terminal velocity! Thank you all for your help!
|
askscience
|
http://www.reddit.com/r/askscience/comments/2ld9vd/sup_everyone_i_was_wondering_about_terminal/
|
{
"a_id": [
"clto0xb"
],
"score": [
24
],
"text": [
"A body falling to the earth is being pulled by gravity with a force equal to its mass times the gravitational acceleration of the earth (9.8m/s^2) -- F=mg. If there's nothing (like air resistance) to oppose that force, a body will continue accelerating indefinitely. So say, on the moon, there is no terminal velocity.\n\nThe force opposing a body in the air is drag, which depends on the shape of the body and the properties of the air you're falling through. Drag can be determined by \n D=1/2 * rho * V^2 * C_D * S\nwhere rho is the density of the fluid, V is the velocity of the object, S is a reference area (say, the frontal cross-sectional area of a falling object), and C_D is the \"drag coefficient.\" C_D is something you can determine experimentally or numerically which depends primarily on the shape of the body, and secondarily on particular properties of the flow (mach number, reynolds number, etc). An arrow will have a much lower C_D than a brick, for example.\n\nWhen the drag force pulling you back equals the force of gravity pulling you down, you've reached the equilibrium \"terminal velocity.\" Determining how long it takes to reach is then a straightforward calculus problem."
]
}
|
[] |
[] |
[
[]
] |
|
a9ha9m
|
How do we know TREE(3) is not infinite but at the same time don't know the upper bound for it?
|
I was watching [Numberphile's video](_URL_0_) on how TREE numbers work and in the video they said TREE(3) is much more massive than Graham's number (effectively Graham's number would be 0 compared to TREE(3)).
They said that it is known that TREE(3) is not infinite but there is currently no known upper-bound. How was it proven that TREE(3) is not infinite?
Also, does this proof extend to all TREE numbers or is there a number where TREE(N) becomes infinite?
|
askscience
|
https://www.reddit.com/r/askscience/comments/a9ha9m/how_do_we_know_tree3_is_not_infinite_but_at_the/
|
{
"a_id": [
"ecmfw9t"
],
"score": [
7
],
"text": [
"Kruskal's tree theorem states that trees with well quasi ordered labels are themselves well quasi ordered under embedding. This means that any infinite sequence of them must have two such that the former is embeddable in the latter.\n\nSince the colors (labels) in the definition of TREE are well quasi ordered (because they are finite discrete sets), the condition of the theorem holds and no such sequence of trees can be infinite (since the definition of TREE states that they are not allowed to be embeddable). Therefore it must be finite, and this holds for any value of n (and more, as long as it’s well quasi ordered).\n\nA similar proof shows that Friedman’s SSCG() function is finite, this time using the Graph minor theorem.\n\nEdit: on mobile, so a bit terse. "
]
}
|
[] |
[
"https://www.youtube.com/watch?v=3P6DWAwwViU"
] |
[
[]
] |
|
3nxx3d
|
what happens if all ten non permanent members of the un security council vote against a resolution but all five permanent members vote for?
|
explainlikeimfive
|
https://www.reddit.com/r/explainlikeimfive/comments/3nxx3d/eli5_what_happens_if_all_ten_non_permanent/
|
{
"a_id": [
"cvs8tpd",
"cvs9ccw"
],
"score": [
5,
2
],
"text": [
"In order to pass, a resolution most fulfill both of the following:\n\n- All 5 permanent members must vote for it.\n\n- A majority of all security council members must vote for it.\n\nThe resolution would not pass. The UN's system is designed to favor inaction as a means of keeping belligerents at the table.",
"The resolution fails. Any resolution needs majority support, but no resolution can pass with a \"no\" vote of any of the permanent members."
]
}
|
[] |
[] |
[
[],
[]
] |
||
26u9b9
|
How did specific spelling of english words come to be standard?
|
I cant help but notice when reading older examples of English text. The spelling of words are very very different from our contemporary English words. In most cases there's no fixed spelling for a word, yet today we have a standard of spelling for every word we use. How did this come about?
|
AskHistorians
|
http://www.reddit.com/r/AskHistorians/comments/26u9b9/how_did_specific_spelling_of_english_words_come/
|
{
"a_id": [
"chujho1",
"chun6un"
],
"score": [
2,
2
],
"text": [
"The simple answer is when dictionaries became popular. \n\nThe less simple answer is that English spelling isn't standardised. There are huge differences between British and American English spelling. \n\nUnlike the Romantic languages, for instance, there is no council to formalise English spelling, so words are basically spelled the way they're generally spelled by most people. Even within British English you see multiple spellings for the same word - inquiry/enquiry for example.",
"In the days before the printing press, books were manually produced by copyhouses. There was variation in spelling in accordance with local pronunciation and usage, but each copyhouse kept very consistent spelling in the books that it produced.\n\nThis all fell to pieces with the printing press. Suddenly the same word was spelled in any of the regional variants, even in the same document. In many cases, the compositor picked the spelling that made the printed columns line up nicely.\n\nEventually spelling became standardized, but not in any logical manner. That's why we get mixed up words like \"busy\" where the spelling comes from Wessex, but the pronunciation of East Anglia.\n\n\nHistory of English Spelling: D.G. Scragg.\n\nEnglish and How it Got that Way: Bill Bryson."
]
}
|
[] |
[] |
[
[],
[]
] |
|
4p2vch
|
why do objects in our vision appear to be in different places when we look through one eye closed one eye open.
|
For example if your looking at an object and you close your left eye but keep your right one open and then do the same with your left eye. The object seems to have changed positions.
|
explainlikeimfive
|
https://www.reddit.com/r/explainlikeimfive/comments/4p2vch/eli5_why_do_objects_in_our_vision_appear_to_be_in/
|
{
"a_id": [
"d4hmfxy",
"d4hnl7x"
],
"score": [
6,
2
],
"text": [
"Because your eyes aren't in exactly the same place as one another. They're a few inches apart..You are literally seeing the object from two different angles. Your brain combines the images into one when you have both eyes open so you don't really notice.",
"You have a dominate and non dominant eye; if you're right eye dominant and you close your left eye, whatever you're looking at won't move, but if you close your dominant eye, whatever you're looking at will shift a little bit. "
]
}
|
[] |
[] |
[
[],
[]
] |
|
8g53a7
|
How did we figure out the shape of proteins and other organic compounds?
|
How did scientists discover the true and exact shape of such tiny patterns? The structures of some biomolecules seem to be perfectly 3D scanned shapes
|
askscience
|
https://www.reddit.com/r/askscience/comments/8g53a7/how_did_we_figure_out_the_shape_of_proteins_and/
|
{
"a_id": [
"dy91l7n"
],
"score": [
14
],
"text": [
"The structure of many proteins were discovered by isolating the protein, precipitating it out of solution to form a solid crystal, and then using the diffraction pattern of x-rays passing through the crystal to infer its structure. This technique is called [x-ray crystallography](_URL_0_)."
]
}
|
[] |
[] |
[
[
"https://en.wikipedia.org/wiki/X-ray_crystallography"
]
] |
|
4x5ped
|
how can there be a scientific adam and eve if there would of been multiple ancestors?
|
I heard my teacher saying theres a scientific eve which we can trace all humans to but they would of been many homo neanderrhals etc
|
explainlikeimfive
|
https://www.reddit.com/r/explainlikeimfive/comments/4x5ped/eli5_how_can_there_be_a_scientific_adam_and_eve/
|
{
"a_id": [
"d6cpi1h",
"d6cqj5z",
"d6cvwhg"
],
"score": [
6,
2,
3
],
"text": [
"It's called the most recent common ancestor. Basically all other lines of decent have died out at some point so we're all related in some way. At the time they lived, there were other people about, but all other decedents died off or were married into, leaving us all decedents of one common ancestor. ",
"\"Mitochondrial Eve\" and \"Y-chromosomal Adam\" were not alive at about the same time (most likely; if they were then it's random chance). They were not the first humans and didn't come just after neanderthals.\n\nTo figure out who Mitochondrial Eve is, imagine that there's a family. One couple has two daughters and those daughters go off and make a dozen grandchildren. Then everyone else on earth dies. \n\nAt this point every remaining human can look at their mother, then their mother's mother and they wind up at the same person. That person (i.e. the woman in the original couple) is now Mitochondrial Eve. It's a title that can move down generations whenever someone's line of offspring die off. Similarly, if the children look at their father (whoever married one of the two original daughters in our example) and their father's father, and so on, then they will *not* find a common ancestor (tracing only by looking at fathers) so easily. You'd have to trace likely hundreds of generations before you find one person who is every living human's father's father's father's ... father's father.\n\nNote that neither Mitochondrial Eve nor Y-Chromosomal Adam are the most recent common ancestor, either. For this we just have to tweak our scenario: instead of the original couple having two girls they have a boy and a girl (call 'em Alice and Bob), who each find a mate and make half a dozen children. Then everyone else on earth dies.\n\nWith this setup if you looked for Mitochondrial Eve then the children of Alice would look at Alice, then Alice's mother, and so on, while the children of Bob would look at Bob's wife, then her mother, and so on. It would take likely hundreds of generations to figure out who is everyone's mother's mother's mother's ... mother's mother. Same with father's father's ... father's father. But if you just want a common ancestor then you look to the original couple, as they're everyone's grandparents.",
"As others have said: Mitochondrial eve.\n\nAlso:\n\nSHOULD. HAVE.\n--\n\nwhere the bloody hell did this \"should of\" nonsense come from?!?"
]
}
|
[] |
[] |
[
[],
[],
[]
] |
|
33ppa2
|
When someone has an allergic reaction, such as from being stung by a bee, what exactly is going on?
|
askscience
|
http://www.reddit.com/r/askscience/comments/33ppa2/when_someone_has_an_allergic_reaction_such_as/
|
{
"a_id": [
"cqok1ys",
"cqovn55"
],
"score": [
2,
4
],
"text": [
"Bee venom contains proteins, which are foreign to your body. If your immune system recognizes a foreign protein, it can trigger a response to that protein. How the immune system responds will depend on the nature of the foreign protein, the individual's exposure to that protein in the past, their genetics, and many other factors that can affect the resting immune state. \n\nIn most cases, the immune response will be harmless, but some individuals can have hypersensitive responses to these foreign proteins, which will trigger autoimmune symptoms like hives or in extreme cases, anaphylaxis. ",
"This type of allergic reaction is called a type 1 hypersensitivity. To break it down for you, we have 4 main cell types involved and a few main chemical messengers. First the bee venom, or antigens, are captured by antigen presenting cells (dendritic cells). Think of them like the body's surveillance system for foreign substances penetrating the skin. The dendritic cells then present the antigen to a type of T-lymphocytes (TH2 cells). TH2 cells are sort of like the supervisors of all the other white blood cells. They secrete chemical signals, called cytokines, to other cells to let them know what they should be doing and where they should be going. So anyway, after the TH2 cells are presented with the bee venom antigens, they start to secrete one of the cytokines which signals another type of lymphocyte, called a plasma cell, to start making and secreting a bunch of antibody that will be able to later bind specifically to the bee venom antigen. However, before the plasma cells can start making the antibody, they also must have been presented with the antigen. An important point here is that in the case of type 1 hypersensitivity, it is not just any old antibody that is made, it's a specific antibody called IgE. The IgE then coats the outside surface of another white blood cell called mast cells. Mast cells are a special cell filled with little packets of chemicals called histamine and heparin. Think of IgE coated mast cells as little mine fields waiting to burst when a potentially dangerous foreign material gets near them. The IgE now coating their surface can bind to the bee venom antigen when it comes into contact with it. When this happens, the mast cell is activated to degranulate. In other words, it squirts out all its histamine and heparin. These two chemicals cause blood vessels to dilate and become leaky, leading the the swelling and redness you see with a bee sting. The problem with someone with a severe reaction is that their body already has a lot of mast cells with IgE specifically ready to bind to bee venom from previous exposures. When any bit of venom enters the body, mast cells all over the body start to degranulate leading to a lot of dilated leaky bloody vessels and therefore a lot of swelling. Also, when there is enough histamine in circulation, it can cause the airways to constrict. This is why people with severe allergies to bees, or other things, can have extreme difficulty breathing during an episode. Antihistamine drugs, help fight these reactions by blocking the receptors that histamine binds to. However, in severe anaphylactic reactions antihistamines won't get the job done. This is why people with very severe bee allergies often carry epinephrine shots (epi-pens). Epinephrine counteracts the constriction of the airways by binding Beta-2 adrenergic receptors leading to dilation of the airways, and counteracts the leakiness/dilation of the blood vessels by causing them to constrict thru binding alpha-1 adrenergic receptors. This is a detailed, yet still extremely simplified explanation, but I hope it was informative. Source: took veterinary immunology about a year ago. \n\nTLDR: Bee sting allergy = type 1 hypersensitivity"
]
}
|
[] |
[] |
[
[],
[]
] |
||
49odwh
|
[Astro] Does our Sun radiate anything else other than photons?
|
askscience
|
https://www.reddit.com/r/askscience/comments/49odwh/astro_does_our_sun_radiate_anything_else_other/
|
{
"a_id": [
"d0tg8nl"
],
"score": [
68
],
"text": [
"Yes, plenty of stuff. For one, the fusion reactions that power all the good stuff also produce neutrinos. These are extremely light particles (the lightest particles with non-zero mass that we know) that almost never interact with other particles. Right now, there are hundreds of milions of neutrinos going through your hand every second.\n\nSince the plasma that the sun is composed of is largely very hot, parts of it can escape into space. This is called the solar wind, which is comprised primarily of protons, electrons and helium nuclei (alpha particles). Since these are all charged particles, their heading is altered by magnetic fields. On Earth, the geomagnetic field causes solar wind particles to be redirected towards the poles. The interaction of these particles with the atmosphere causes the aurora borealis (northern lights) (and the equivalent near the south pole). "
]
}
|
[] |
[] |
[
[]
] |
||
3d23rh
|
If I were to cross the Atlantic in 1875 from New York to London, or some other large European port city, how long would it take and what type of liner would I be on?
|
Also, what would I do during my stay on the ship? Was there entertainment? Food? Laundry? Would all of this depend on ticket price and social class?
|
AskHistorians
|
http://www.reddit.com/r/AskHistorians/comments/3d23rh/if_i_were_to_cross_the_atlantic_in_1875_from_new/
|
{
"a_id": [
"ct15726"
],
"score": [
5
],
"text": [
"Let's talk for a moment about what you *wouldn't* have. There would be no electrical lighting (that was a first aboard the *Columbia*, built in 1880). There would be no refrigeration. It wouldn't be steel-hulled (that would come with the *Servia* of 1881). It would likely be a steamship (though there were sail-only vessels still in use), burning coal with auxiliary sails. Rather than New York to London, you'd likely sail to Liverpool instead — that port was popular with ships heading across the Atlantic, since it cut travel time.\n\nA five-year shipping depression began in 1873 with the Panic of 1873, so you probably wouldn't have had to pay much — as long as you had the money to spend, which many didn't. \n\nYour ship would carry both cargo and passengers, as the passenger-only liner wasn't developed until about 1879, when William Pearce built the *Arizona* in his belief that a market existed for a fast, passenger-only liner. The Arizona could cross the Atlantic at 16 knots, but it burned an exorbitant amount of coal to do so. In 1875, the holder of the Blue Riband (a term we use today for the fastest crossing) was the *City of Berlin*, which crossed in 7 days, 18 hours and 2 minutes at an average speed of 15.21 knots. The *City of Berlin* was also the largest passenger ship in the world (except for the *Great Eastern*, of course, but that ship was all but laid up in 1875), carrying 202 first-class and 1,500 steerage passengers in a hull just shy of 490 feet long.\n\n*City of Berlin* was a member of the Inman Line, which was competing with the White Star Line and several other carriers for passenger service on the Atlantic. In 1875, the White Star Line's *Oceanic*-class liners were brand new and making a name for themselves with their quality. These included the namesake of the class, the *Atlantic,* the *Baltic,* and the *Republic.* This first run of *Oceanic* ships was followed by the *Celtic* and *Adriatic* after the class proved successful. Larger versions of the class were built as the *Britannic* and *Germanic* in 1874 and 1876, respectively.\n\nThe *Oceanic* could carry 166 first-class passengers (called saloon passengers) and 1,000 steerage passengers plus a crew of 143 in a hull 420 feet long. This was a high-quality ship, with running water in most first-class cabins and electric bells to summon a steward. There was as yet no electric lighting, however. First-class was amidships, away from engine noise and with a calmer ride in violent seas. Third class was at the bow and stern of the ship, with single men in the bow and single women, married couples and families in the stern.\n\nAn 1874 account says the *Republic* was like a \"floating palace\" in first class, with a piano, library, smoking room and barber. First-class also had bathtubs and a dining saloon with chairs rather than benches."
]
}
|
[] |
[] |
[
[]
] |
|
4iljw7
|
why does your body allow you to sleep if you're about to die?
|
[deleted]
|
explainlikeimfive
|
https://www.reddit.com/r/explainlikeimfive/comments/4iljw7/eli5_why_does_your_body_allow_you_to_sleep_if/
|
{
"a_id": [
"d2z1ro7",
"d2z1sie",
"d2z95mh"
],
"score": [
8,
2,
2
],
"text": [
"Your body doesn't \"know\" that medical intervention could potentially save it. Your body doesn't even \"know\" what medical intervention is; only that if your body's natural defenses have been exhausted, there's nothing left to fight what's attacking it. Speaking of which, your body is probably tired if it has been fighting something for some time. It rests for the same reasons anything rests; to recharge. ",
"I don't generally agree with the statement \"survival at any cost mode\" - this doesn't really happen, although we do have a good number of defenses and adaptations that have allowed us to avoid extinction. However, specifically, we have no knowledge here that falling asleep increased his chance of death - it may have well decreased it, but not sufficiently to avoid it. The body has not evolved with the possibility of medical attention as next step!",
"Sleeping or a coma is a way for the human body to spend more time on recovery and repair - not spending energy on movement, higher brain functions, talking, etc. Comas are often induced after head trauma to facilitate healing. \n\nIt sounds like the actor had a heart attack - the arm pain can be typical. In the case of a heart attack, part (or all) of the heart muscle is dying from lack of blood flow. Therefore, the heart is not pumping blood as efficiently as it designed to. Decreased blood flow means decreased oxygen in the blood; low blood oxygen tends to make people groggy/tired. "
]
}
|
[] |
[] |
[
[],
[],
[]
] |
|
2b4r54
|
why don't those with authority (such as police officers) face the same penalties as ordinary citizens for crimes?
|
I'm just curious because everyday I hear about injustices to citizens from police offers, however they only get measly penalties such as being fired, whereas a normal person would be jailed, fined heavily, etc.
|
explainlikeimfive
|
http://www.reddit.com/r/explainlikeimfive/comments/2b4r54/eli5why_dont_those_with_authority_such_as_police/
|
{
"a_id": [
"cj1rvkb",
"cj1slut"
],
"score": [
33,
7
],
"text": [
"Officers are put into legally problematic positions as part of their jobs. For example it is the duty of an officer to use their service weapon to stop an armed criminal before they can injure or kill others. But if the officer makes a mistake the officer could injure or kill innocent bystanders. A regular person could avoid the whole issue by not firing at all, but an officer has a duty to fire; the reduced punishment in the event of a mistake is acknowledgment of the dissimilar circumstances.",
"In some cases, it's because there are some protections in the law that are specific to people in certain positions. For instance, in general, it would be a crime if I were to tie someone's hands together and hold them captive. A police officer, on the other hand, needs to be able to do this to accomplish their job and always runs the risk accidentally arresting an innocent person. As a result, the law recognizes this difference and gives cops a lot more leeway for something like this. As a result, I might be charged for kidnapping and battery for \"arresting\" someone, but the cop would not. \n\nAnother reason is based on reporting of events. If a police officer beats up someone while on duty, that's probably going to be newsworthy and you might hear about it. Perhaps media coverage will die down and you'll never hear about the full punishment the offender faced. Perhaps you will hear more coverage and if there's a light sentence, there will be outrage. However, if there's an altercation between, say, a husband and wife, you're not going to hear about that on the front page of the paper. And if one of those spouses gets a light sentence, few people will care so there won't be much outrage. \n\nTL;DR: Some professions require certain legal protections in order to do their jobs. Also, crimes by people like police draw media attention differently, so they're more likely to provoke outrage. "
]
}
|
[] |
[] |
[
[],
[]
] |
|
76luw2
|
if proteins and enzymes denature at high temperatures, how do animals such as tardigrades survive under these conditions.
|
explainlikeimfive
|
https://www.reddit.com/r/explainlikeimfive/comments/76luw2/eli5_if_proteins_and_enzymes_denature_at_high/
|
{
"a_id": [
"doezdke",
"dof394e"
],
"score": [
9,
6
],
"text": [
"They have proteins that are designed to retain their shape at high temperatures. In fact, it's possible that those proteins won't function under more normal temperatures.",
"I can't speak about tardigrades specifically, but in many animals and humans, we have what are called heat shock proteins. These proteins are chaperone proteins and helps to properly fold other proteins when other there is stress on the cell like heat and UV radiation."
]
}
|
[] |
[] |
[
[],
[]
] |
||
1kj1lx
|
How far back does the practice of breeding animals/plants for desired traits go?
|
I'm familiar with the development of agricultural fairs and awards in the 19th century, but were there practices before this? Are there any instances before the acknowledgement of inherited traits and evolution?
|
AskHistorians
|
http://www.reddit.com/r/AskHistorians/comments/1kj1lx/how_far_back_does_the_practice_of_breeding/
|
{
"a_id": [
"cbpknqz"
],
"score": [
4
],
"text": [
"Arguably, this happened at the very beginning of agriculture and husbandry. Planting any crop will promote that particular species, and of that species that particular strain, over others. If you use the seeds of that crop just once, it is because of local pollination, reinforcing the traits of the crops you planted. Exactly when someone decided to plant the seeds of the desireable plants vs undesireable is impossible to answer, but it must have happened before recorded history (since recorded history relies on a fairly advanced civilization, which relies on a stable crop, which can only be achieved through domestication of wild species).\nSome examples of domestication are wild grass to corn and wheat, or wild aurochs to cattle."
]
}
|
[] |
[] |
[
[]
] |
|
4l3cu2
|
What did the average person think about the atomic bombs at the end of WW2?
|
By average I mean non physicists.
Did people just shrug their shoulders and accept that 1 bomb could have that much power? Did they think that they were being lied to due to wartime censorship?
|
AskHistorians
|
https://www.reddit.com/r/AskHistorians/comments/4l3cu2/what_did_the_average_person_think_about_the/
|
{
"a_id": [
"d3ke609"
],
"score": [
6
],
"text": [
"I've never seen anything that indicated that any substantial number of people thought they were being lied to. One should remember that the physics underlying the bomb (nuclear fission) was known before the war began, and that the list of eminent scientists working on the project was extensive. The Smyth Report, published a few days after Nagasaki, treated the subject of how they were made and worked in enough technical detail to be compelling to anyone with some technical background (part of its explicit purpose was so that technically-minded people — engineers, for example — could understand the new weapon and explain it to others). A great publicity barrage followed the bombing of Hiroshima, explaining what the bombs were, how they worked (not in detail, of course), who made them, where they were made, etc. We could think of this as in part fleshing out the backstory narrative as part of making it more evident how this new thing just suddenly appeared — the publicity was directed at the Japanese as well.\n\nThe notion of a giant conspiracy between the government, the scientists, the photographers, etc. — just not the sort of thing you'd see in 1945. (This is not to say that there weren't what we'd call conspiracy theorists in the 1940s, but it was more along the lines of \"FDR knew about Pearl Harbor\" not \"every scientist is faking evidence.\") One can find _someone_ who believes anything but there is no evidence that anyone of significance or any people in great numbers doubted the existence of the atomic bomb.\n\nAlso, separately, the notion that atoms contained lots of energy bound-up in them, that could be released in various ways, was very well-established in popular culture by the 1940s. Even the notion of an \"atomic bomb\" was a well-known science-fiction staple since the late 1910s. So it was not as jarring an idea as one might imagine. If scientists announced that they had created a wormhole tomorrow, and provided data to prove it, many people would have some idea of what they were talking about, even if their knowledge of what that meant was primarily mediated through works of fiction.\n\nThere is more that could be said about public opinion (there were polls taken about whether people thought atomic bombs would be used in future wars, etc.), but it seems like the above is what you are getting at. "
]
}
|
[] |
[] |
[
[]
] |
|
2aw3s4
|
big data
|
Could someone explain what exactly Big Data is. Is it a specific technology, or a term about different technologies.
If you could also explain to me some barriers for it to become mainstream, and why it is just starting to gain ground now
|
explainlikeimfive
|
http://www.reddit.com/r/explainlikeimfive/comments/2aw3s4/eli5big_data/
|
{
"a_id": [
"cizcemj"
],
"score": [
4
],
"text": [
"It's something of a buzzword and lacks a concrete definition. However, the idea is that our computational power now allows us to gather, store, and analyze vast amounts of information - magnitudes more than twenty or thirty years ago.\n\nThe implication is that the hugely increased scale of this data manipulation leads to a qualitative (not just quantitative) shift in both the tools that we need for working with it, and the benefits we get from analyzing it."
]
}
|
[] |
[] |
[
[]
] |
|
30czy4
|
what algorithm or code is used to program traffic lights?
|
Who writes these codes? Are they somehow autotomatically adapting? If they are manually changed, who makes the decisions for the times and frequency the lights change?
|
explainlikeimfive
|
http://www.reddit.com/r/explainlikeimfive/comments/30czy4/eli5_what_algorithm_or_code_is_used_to_program/
|
{
"a_id": [
"cpr90z8"
],
"score": [
4
],
"text": [
"It's probably the city planning department. There may even be a traffic management sub-department, if the city is big enough.\n\nYou know how sometimes there's those [black tubes hooked up to a small box](_URL_1_) that's chained to a sign or post that stretches across the road? Those are car counters. That data is used to see traffic flow over time along various roads and intersections, and that, in turn, is used to tune the light cycles (which do change depending on time of day).\n\nYou may also notice [big loops engraved on the road](_URL_0_) (usually in the turn lanes) with lines running off to the traffic control box. Those are sensors which tell if there's a car there or not. Those also feed data into the control box and makes it so it doesn't stop oncoming traffic for cars to turn if there are no cars waiting to turn.\n\nTraffic management is a big deal. A lot of money goes into making and tuning the models used to tune the traffic lights for optimal traffic flow. Please note that \"optimal traffic flow\" doesn't mean \"every light has as few a people waiting the shortest time possible.\" For example, if one particular on ramp to a highway gets really congested, it could back up traffic for miles in every direction, both on the surface streets feeding it, and on the highway where people have to make room for a constant string of cars. The lights leading to that on ramp can be tuned in such a way as to limit the flow of traffic to that on ramp, making traffic flow better even though the lights themselves seem to be nonsensical in their timings.\n\nThat said, we need more roundabouts! Those things push more traffic through an intersection with greater safety than signals. But they do take up more room."
]
}
|
[] |
[] |
[
[
"http://i00.i.aliimg.com/img/pb/438/452/093/1093452438_607.jpg",
"http://www.cityofknoxville.org/images/engineering/traff_counter.jpg"
]
] |
|
7cg6rj
|
Why does it feel like jalapeños are actually burning your skin?
|
After de-seeding them...
|
askscience
|
https://www.reddit.com/r/askscience/comments/7cg6rj/why_does_it_feel_like_jalapeños_are_actually/
|
{
"a_id": [
"dprns63"
],
"score": [
4
],
"text": [
"The reason that chillies (and other foods) are spicy is mostly due to the chemical capsaicin. This is a naturally occuring compound, found in particularly high concentrations in things like jalapeños.\n\nCapsaicin is able to activate a particular type of nerve in your skin, one that is more commonly activated by being burned or scratched. As your body isn't able to distinguish *what* activated the nerve, just that it *has* been activated, this signal is interpreted as being caused by an actual burn or scrape.\n\nThe body then reacts accordingly, with inflammation, and pain. No actual damage is done, but it sure feels like it."
]
}
|
[] |
[] |
[
[]
] |
|
eplcfb
|
During the various Latin American independence movements the majority of the new countries turned to a republican system, and yet Brazil became an Empire, why was this?
|
AskHistorians
|
https://www.reddit.com/r/AskHistorians/comments/eplcfb/during_the_various_latin_american_independence/
|
{
"a_id": [
"fj6cybc"
],
"score": [
9
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"text": [
"I don't know the history of the rest of Latin America independences but I can tell you the Brazilian history. English isn't my first language so sorry for any mistakes. \n\nAfter the Napoleon troops invaded Portugal in november 1807, heading to Lisbon, the prince Dom João decided to transfer the court to Brazil. Upon arriving he issued several measures that effectively ended Brazil colonial status. Dom João VI in the following years tried to better integrate Brazil and Portugal and, in 1815, promoted Brazil to \"United Kingdom to Portugal and Algarves\". \n\nIn 1820, however, Portugal had a liberal revolution. The Portuguese pressed for the return of the king to Portugal, in part due to their own internal crisis. The portuguese desired to return Brazil to the status of colony. In the end of 1820 a Court created for writing a Constitution with representatives of all of the Portuguese world\nIn Rio de Janeiro Portuguese defended the king return to Portugal and There were Brazilians and \"adapted\" Portuguese, those whose interests aligned with the colony, that desired and worked for the stay of the king. Dom João, however, feared losing the crown so he went to Portugal, leaving his son, Pedro, as regent prince. \n\nOnce the king returned, there were elections for the representation of Brazilians in the Court. The conflicts between the brazilian and portuguese interests were too big and the independence option got more and more interesting. \n\nBrazilians focused on keeping Dom Pedro in Brazil. His decision to stay was consagrated on the 9 of January of 1822 also known as the \"Dia do fico\"^1 . The country wasn't yet independent. That came only after the prince, upon the arrival of dispatches revoguing his decrees, gave the famous \"grito do Ipiranga\"^2 saying \"independencia ou Morte!\"^3 7 of september of the same year.\n\nThat's how and why Brasil became/remained an empire after it's independence. Source:\n\nFausto B. **História concisa do Brazil**. 3ed, 2018.\n\n1. Day of I stay\n\n2. Yell of Ipiranga\n\n3. Independence or Death!"
]
}
|
[] |
[] |
[
[]
] |
||
4g9tln
|
what is the advantage of uber/ lyft over traditional cabs?
|
I ask because it seems like there often isn't a large cost difference so that can't be the game changer. You can schedule them with an app but you can do that with a lot of traditional cab companies now too. I don't have a dog in the hunt, just curious. What makes this revolutionary?
|
explainlikeimfive
|
https://www.reddit.com/r/explainlikeimfive/comments/4g9tln/eli5_what_is_the_advantage_of_uber_lyft_over/
|
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"I'm in Eastern/Central Europe so this may be different, but:\n\n- uber is cheaper\n- traditional cabs worked like mobs for a very long time, they still have a lot of shady practices (overcharge, extort, etc.)\n- not all cab companies have mobile apps\n- with uber you don't have to wait around to pay, you don't have to take out your wallet, cabs will sometimes refuse credit cards\n- for foreigners, with uber they can just type in the destination, plus cab drivers are mostly old and don't speak languages",
"They are typically cheaper, they are available on demand via an app (call for a cab & they'll arrive like 30min later -- maybe), typically nicer cars/drivers.",
"Uber is extremely cheap, more fairly priced imo. My boyfriend two timezones over was able to get me an uber that arrived within 10 minutes. And the driver was personable, polite, etc. When I looked up fare for cabs and tried to figure out how to get one it was much more complicated and cost 2 and 3 times as much for the same distance. ",
"It's considerably cheaper. Especially in places with heavy traffic or even with long distances. Plus, while there are \"hussles\" in Uber and Lyft the driver can utilize to squeeze more money out of you, in general it's more regulated prohibiting the drivers from being pricks. \n\nIt's the preferred method of transportation here. No hassle, generally kind people, cheaper, cleaner, less drama and so much so that the cab companies protest and block traffic on occasion because they're losing money hand over fist. \n\nIt's a game changer when the cabbies are notoriously awful. ",
"Cabbies were consistently late with no assurance they were even going to show up. Sometimes wouldn't take credit. But the final straw was two separate instances of cabbies going to long way to rack up the fare. At this point doesn't matter what cabs do, I'm forever a Lyft or Uber customer. The trust is gone. ",
"Another aspect of Uber that's beneficial is the surge pricing adjusts supply to meet demand, so that if the weather is terrible or it's New Year's Eve, etc. you can actually get one. Sure, it'll cost more, but better than waiting hours for a cap in a storm.",
"There *is* usually a cost difference. That's the whole reason they can be competitive.\n\nCab companies had to develop apps *in response to* Uber/Lyft etc. Before them, there was no reason to develop an app when that same phone could simply be used to call the cab company for a cab."
]
}
|
[] |
[] |
[
[],
[],
[],
[],
[],
[],
[]
] |
|
2cju3p
|
what would happen if a camera at the end of a rope is "thrown" through a black hole?
|
Hi Reddit. I have no background in the field of Physics, or any science for that matter. I was wondering what would happen if we were to tie a live-recording camera to the end of an extremely long rope and somehow throw it through a black hole, assuming whoever is at the other end of said rope isn't sucked in or something.
|
explainlikeimfive
|
http://www.reddit.com/r/explainlikeimfive/comments/2cju3p/eli5_what_would_happen_if_a_camera_at_the_end_of/
|
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"text": [
"The camera would just be crushed due to the intense gravity as far as I know",
"The camera would be crushed, as would the rope. Neither would function or continue to exist as objects you'd recognize as \"rope\" or \"camera\".\n\n",
"The acceleration of objects near a black hole increases so exponentially that the camera would be ripped to shreds.\n\nIf for some reason (for the sake of argument) the camera remained whole it would just be crushed as it approached the intense gravity.",
"If by asking this question, you mean to ask \"what does the inside look like?\" Vsauce (on YouTube) has a good video about that; can't link as I'm on iPhone, sorry.\n\nYou might have been confusing black hole (hyper-dense object with immense, inescapable gravity) with wormhole (hole in space-time, I think?) in this case, I'm not sure we have an agreed upon hypothesis about what wormholes \"do\" when matter enters."
]
}
|
[] |
[] |
[
[],
[],
[],
[]
] |
|
3soosb
|
why do anime episodes often get removed from youtube for copyright but never get removed on sites like crunchyroll?
|
explainlikeimfive
|
https://www.reddit.com/r/explainlikeimfive/comments/3soosb/eli5_why_do_anime_episodes_often_get_removed_from/
|
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"text": [
"CrunchyRoll pays the studios for the anime and either you pay a fee or have to watch commercials (or not if you use adblock)",
"Crunchyroll is a streaming company that negotiates licensing fees with content owners and anime studios. \n\nYoutube is simply a site where anyone can upload a video. So if someone random person uploads someone else's creation to try and make ad money, it gets removed. Since Crunchyroll pays the content producers and gets signed licenses allowing them to stream the content, they are allowed to.",
"Presumably because Cruncyroll is an anime hosting service that has gone through all of the legal steps to display the content. While some random user on YouTube has not, and YouTube takes it down because they don't want to host copyright content without the permission of the distributer."
]
}
|
[] |
[] |
[
[],
[],
[]
] |
||
19w13p
|
how does a group like skidrow crack games' drm?
|
How can they see what the protections are and how do they crack them? And how so quickly?
|
explainlikeimfive
|
http://www.reddit.com/r/explainlikeimfive/comments/19w13p/eli5_how_does_a_group_like_skidrow_crack_games_drm/
|
{
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"c8s336v"
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"text": [
"Think of a game - or any computer program - like a recipe. Do this, do that, do this other thing. At some point in a copy-protected game, it'll do some check to see if it's allowed to install or run; maybe check a serial number or make sure the right disk is in the drive or (and this is old school) ask for the 4th word on the 10th line of page 43 of the manual. \n\n\"Cracking\" basically involves messing with the recipe so that the game is fooled into accepting any serial number or not actually checking for the disk or or whatever.\n"
]
}
|
[] |
[] |
[
[]
] |
|
1eudxr
|
How was a razed city re-organized, if the conqueror did not actively annex and re-colonize it?
|
I'm currently reading a historical fiction novel which covers the devastation of Kiev after it had been razed by the Mongols. I might be wrong on this, but my impression is that unlike Carthage which was eventually recolonized by the Romans after its razing, the Mongols didn't send out groups of settlers to Kiev. So I had a few questions on how cities that were razed were rebuilt - I'm using Kiev here as a specific example, but I'd be interested in any ancient city that fits the same conditions of
A) large parts of the city being physically destroyed,
B) having a significant percentage of the population killed/deported
C) the conquering power did not take active steps to rebuild the city.
Questions
1) Even the most brutal razes left some survivors. Would a rebuilt city generally have the majority of the population made up of survivors, or would people from nearby villages take advantage of the situation to migrate and claim parts of the city?
2) How would a government be set up? If the previous ruling family did not leave any clear heirs, would the survivors simply pick their leaders in a semi-democratic fashion and would that leader become a new noble? Or would there almost always be a foreign noble who would come in and claim ownership?
3) If large numbers of property holders were killed, how would their property be redistributed among survivors? Was it considered generally fair to let survivors enlarge their property claims if they rebuilt their claimed lands before a new government was in place?
|
AskHistorians
|
http://www.reddit.com/r/AskHistorians/comments/1eudxr/how_was_a_razed_city_reorganized_if_the_conqueror/
|
{
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"text": [
"I can speak from a Byzantine perspective.\n\nThe Eastern Roman/Byzantine Empire in the 7th century saw most of its Anatolian cities sacked multiple times by Arab raiders/invaders, with many cities outright abandoned, and the few surviving cities really only surviving as fortified military outposts. \n\nThe abandoned cities were abandoned because even if the city wasn't successfully sacked, the constant Arab raids were massively disruptive to the agricultural economy in the surrounding area that the city needed to support its existence. No farmers, no safe transportation, no trade, no money, no city.\n\nIn general, once a city is sacked, unless there are compelling economic reasons or political will from the conquerors or the previous inhabitants to rebuild, that city will not come back. Even if there is will to rebuild, it requires extraordinary investment for it to return to any semblance of its former city glory quickly. Without which, a surviving city has to regrow itself organically, which could take hundreds of years.\n\nA few modern examples, and one ancient/medieval.\n\nLook at Berlin and Warsaw after World War 2. These were cities that were essentially razed to the ground. However they bounced back within less than a decade, because there were compelling economic and political reasons as well as investment for their rebuilding. Now compare that to modern day Detroit, which has suffered no war, and no brutal sacking, but large parts of it look like a ruined warzone, which results from negligence due to insufficient economy. It looks that way because the economic incentive for its existence is shrinking. No money, no city. \n\nByzantine Constantinople is simultaneously a common example as well as a special exception. After its sack in 1204, the city lost a vast amount of its population, as well as its economic security. Even after its recapture in 1261, the city no longer had the wealth or the infrastructure from before, and their territory and military was not powerful enough to enforce the trade to wind its way into the city. \n\nBy 1453, Constantinople had gone from several hundred thousand in population to 50,000. In the 250 years until its fall, it in fact never actually recovering its pre-fourth crusade population because there was no one around to infuse it with new cash to rebuild. I mean, the crusaders essentially just sacked the only bank that could've rebuilt the city, as they had no interest in rebuilding themselves. Only after Mehmed II took the city in 1453 was the city rebuilt to great glory, because he DID have the cash and the political will to invest heavily into its rebuilding, making it his capital. Within 50 years it was back to its pre-fourth crusade population.\n\nSo to reiterate, in general after the sack of the city, economic necessity (if the city is in too good a trading location) or political will (leaders are willing to invest the resources to rebuild) are the reasons why a city would re-emerge. If the conditions for the first cease to exist (because the trade routes have been re-ordered, or the economic support of the surrounding area disappears) and there's no will for the second, that city will be abandoned.\n\nIf only the first condition (the economic) exists without the second (the political will), the city may rebuild, but it will take hundreds of years, which means rest assured, no one will be caring about property deeds to survivors for quite some time because there's only smoking ashes left. You can build where you want because nobodys really around to dispute your building.\n\nIf only the second condition (political will and presumably cash) exists, the sky's the limit. They can do as much or as little as they want with the city. They can rebuild it from scratch, or just reoccupy a small portion of it.\n\nEDIT: Figured I should answer your questions more directly, 7th century Byzantium obviously, but this is the time of the greatest destruction to cities and urban population.\n\n1. Yes. Many of the surviving Byzantine cities received influxes of refugees from abandoned cities. No, frequently villagers would not migrate to claim this empty/sacked city because the entire area around the city wasn't safe. Frequently the villagers and farmers were in fact the first to be targeted by the raiders/invaders, so they would be part of this refugee mix.\n\n2. If a sacked city was going to be re-occupied, its occupation would be organized by the military and ecclesiastical bureaucracy selected out of Constantinople. It's a funny thing you mentioned about \"ruling families.\" The destruction of the economic basis for aristocratic power rendered irrelevant the old aristocracy, which is why surnames disappeared from the Byzantine Empire for a period of 100 years+. What use is being an aristocrat if you have no money and no land? In this time frame of constant sacks and destructive raiding, when the aristocrats lost their property and wealth, they tried to use what connections they could to work in the Byzantine bureaucracy. Since the bureaucracy was \"essentially\" a merit system in this time of crisis, it rendered familial connections moot. Within 3-4 generations of familial history being of no use for advancement, they disappeared from the record. \n\n3. The surviving cities that were sacked and then reoccupied, were literally not cities for possibly another 100-150 years. In the first few years of their existence after a sack, if Constantinople decided that city's position needed to be held, it would literally be just the reoccupied fort/castle, and a reoccupied church, with maybe, MAYBE a handful of determined farmers/villagers working in the empty rubble of the old city. There may have in fact been no trading/market activity in any of these cities, as these were purely defensive/administrative locales. There was also no point to old claims of property, as once again, what use is a claim in an unsafe land, when you have no money nor any way to make money from it? It's like owning a house in a bad part of detroit for $1. So you have a house. But it's not safe, you can't live there, you have no services, and you can't rent it out or make money off of it. What's the point?\n\nEDIT 2: How was a razed (Byzantine) city re-organized, if the conqueror did not actively annex and re-colonize it? Slowly and organically. The city has to regrow itself from scratch."
]
}
|
[] |
[] |
[
[]
] |
|
dz73bf
|
what's dijkstra's algorithm used for in computer science?
|
explainlikeimfive
|
https://www.reddit.com/r/explainlikeimfive/comments/dz73bf/eli5_whats_dijkstras_algorithm_used_for_in/
|
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"Lots of things. It's also known as 'Shortest Path First'.\n\nI can be used for networking to find the shortest route(least number of router stops when sending a message).\n\nIt can be used in databases to slowly optimize the location of data based on where it is needed most.\n\nIt can be used by robots to determine the shortest path to an objective, or an AI to figure out the optimal path by giving certain obstacles a distance value.\n\nIt can be used by game AI to create a map of the shortest path to ending the game or winning based on what is considered a 'path', a path can be a set of moves, and choose to play those moves; a version of this is A\\* or minimax.",
"The beauty of computer science is that there are often ways to represent many different real world concepts in ways that turn out to be the same. If you can think of a problem in terms of positive values on a directed graph, and what you want to find as the shortest route between two points on that graph, then this algorithm can give you an answer.\n\nWhat about maps? You can represent roads as paths on a graph and distance as the number associated with that path. This algorithm would then give you the shortest route between any two spots on the graph. That would mean the shortest set of directions to get where you want to go. If you replace the distance value with a time value you could instead get the fastest route to your destination."
]
}
|
[] |
[] |
[
[],
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||
2bhj9s
|
if it's possible to build up a sleep debt, is it possible to build up a "sleep credit"? if not, why not?
|
If I were to sleep more than I needed to during the week, would that enable me to sleep less at the weekend, in the same way that if I sleep too little during the week I have to "catch up"?
|
explainlikeimfive
|
http://www.reddit.com/r/explainlikeimfive/comments/2bhj9s/eli5_if_its_possible_to_build_up_a_sleep_debt_is/
|
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"We aren't really sure why, but it doesn't seem that something like that can be done. Think about it like your bladder; you can build up a need to urinate, but you cannot urinate so much that your bladder is more than empty.",
"There's a lot of stuff done during sleep, like muscle repair and forging new pathways in the brain based on your experiences from the previous day, that can't be done in advance.",
"Going off on a tangent here, but is there a way to tell when you've repaid all your sleep debt? However much I sleep on the weekend, I never feel completely refreshed and always feel like I could do with a bit more sleep.\n\nPerhaps my debt mountain is so big I'll never pay it off in my lifetime...",
"There was a recent study claiming that part of what happens when you sleep is that some chemical is drained from your brain. This chemical builds up during the time you are awake, and can only be drained when you are asleep. If this picture is correct, then when you have sleep debt it's like you haven't slept enough to fully drain the chemical, and would imply that you can't get a sleep credit, because once the chemical has been drained there is no reason to sleep. ",
"You can run out of gas but you can only fill your tank to 100%.",
"I think you can compare this with rechargeable batteries, if your batteries are full, even if you leave them on the charge (sleep) when they are full, they won't last longer. ",
"I think it can, but it's more like a gradient and there are diminishing returns. There's also the question of quality; 6 hours of optimal sleep is better than 8 hours of interrupted sleep.\n\nIn my experience, getting a lot of good sleep gets me into a position where I'm happier, healthier and have more energy than if I'm just getting an ok amount. I've also noticed that I fatigue slower, have more stable moods and can go for periods with little sleep relatively easily.\n\nI guess what I'm trying to say is that while it may not be possible to get 12 hours every night then go a week without sleep without suffering problems, there's a difference between \"enough\" sleep and \"good\" sleep. And I think that provides some short term sleep credit. \n\nBut this is all anecdotal.",
"An important part of sleep is clearing away the useless information you don't need to remember like what color was the shirt you wore one month ago? What did you eat on July 15 2010? This might not be flattering but imagine your brain is a trash can, when you sleep you rummage through it, you throw out what's useless and keep what's important. You can't build up a trash debt or trash credit the can will always hold the same amount of garbage.",
"You've got a lot of answers saying no you can't have a sleep credit, but in my experience you kind of can. If I know that I'm going to be sleep deprived later in the week (planned vacation - all night driving, or one night only to clean the house) I'll take Benadryl or Nyquil the two previous nights, sleep for 10-12 hours. Then, I can pull one all-nighter without any effects. \n\nYour mileage may vary, do not operate heavy machinery until you know how it affects you yada yada. I also worked nights when I was younger, so maybe I'm just weird.\n\nThe key is the sedative that makes you go to sleep earlier or stay asleep longer than you would have. If I've slept plenty and I try to go to bed at 7pm I just wouldn't sleep, it would be pointless, but add 2 Benadryl and then I can sleep more to build up. It doesn't last long though, it has to be the next night, there is no compounding interest."
]
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b1xd4q
|
Shouldn't there be Quark stars?
|
Since the implosion of the massive stars generally moves down the scale of atomic and subatomic particles, shouldn't there be Quark stars somewhere after the stage of neutron stars?
Since we know a little bit about Quarks could we calculate what such a star might be, how it would look, some of the possible effects it would have on its surroundings?
And could we theoretically predict what kind of gravity pressures Quark stars may withstand? Or even what kind of gravity fields it could create?
Seems a bit strange that stars go Supernovae then into neutron stars - and then straight into black holes. Jumping over the hypothetical quark star stage.
Did anyone explore this possibility or is the answer - we basically dont know?
edit:
I came here to ask for more details about a subject but all i got (except one short answer) were nonsense proclamations from a few ignorant, uneducated and psychologically deranged assholes who immediately started accusing me of nonsense cliche strawmans and ad hominems because of my refusal to bow to their holy proclamations - which they now deleted - and now im made into someone who is rude and "personally insulted them" - by proclamation of equally holy moderators who fall for that idiotic false victimization. And so work as enablers of cliche psychologically deranged internet assholes, instead of science.
YOU CAN ALL GO FUCK YOURSELF!
YOU FUCKING DEVOLVED HYPOCRITES.
Now this is being rude and making personal insults, you dumb pathetic shits.
Fuck you and your threats of a ban. I get more answers from the wiki anyway.
|
askscience
|
https://www.reddit.com/r/askscience/comments/b1xd4q/shouldnt_there_be_quark_stars/
|
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"The interior state of neutron stars is poorly known. It might contain something you could call \"quark star\"."
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|
[] |
[] |
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[]
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|
dxf414
|
if bees dont use all the honey they produce, then why do they continue to make so much more than they need?
|
explainlikeimfive
|
https://www.reddit.com/r/explainlikeimfive/comments/dxf414/eli5_if_bees_dont_use_all_the_honey_they_produce/
|
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"Anticipating the inevitable theft of some or all of it?",
"They don’t know how much honey they will need in the winter. They survive by shivering to keep warm and use honey to fuel their energy. If they run out of honey, the entire colony dies.",
"If you do not burn all the fat you store from eating more than you need why do you keep storing more?\n\nHoney lasts nearly forever and remains safe to eat. There's no negative survival consequ3nve of having more, but having less has an obvious danger.",
"Beekeeper here. Bees make honey to help give them food energy through periods when there is not a nectar flow, like during winter and dry times of the summer. A small hive will not make much honey, a medium hive will make some honey, and a large have will make a lot of honey. A large hive that is full of honey will likely swarm and make more hives.",
"Bees don't actually eat much honey. They usually eat nectar or something they make called \"bee bread\" (and some royal jelly for the baby bees). They will eat honey if they need the food of course, but it is not their primary source of food. Honey is mostly for swarming.\n\nWhen honey bees are doing well enough, the queen lays eggs, one of which will become the new queen and inherit the hive. Except for a few bees left to care for the new queen, all of the other bees leave to set up a new hive at a pre-scouted location. This is called swarming. \n\nHoney then, is the high calorie travel food of bees. Its like bee trail mix. It basically never spoils, so they save it up for when they swarm.",
"If humans don't spend all the money they make, then why do they continue going to work to make more money than they need?\n\nTimes of need are unpredictable and a savings helps you get through it.",
"Preparing and plotting. Bees have no compassion and they ask no compassion from you. When their turn comes, they shall not make excuses for the terror.",
"Bees are eusocial insects. They don’t really have a will or mind individually so much as a collective drive. Worker bees make collect nectar and pollen, make honey, build the hive, and tend to young because their brains tell them so. There is no shutoff switch, so they just keep going and going.",
"Additionally honey is an excellent preservative and helps keep pathogens away from their offspring. The more of a protective shield you give your little ones, the more likely they'll thrive and survive."
]
}
|
[] |
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[],
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||
5m9bcw
|
why do sites like youtube and facebook (but especially youtube) continuously modify their interface with new skin, color, and features, despite the negative reception of their userbase?
|
explainlikeimfive
|
https://www.reddit.com/r/explainlikeimfive/comments/5m9bcw/eli5_why_do_sites_like_youtube_and_facebook_but/
|
{
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"Because everybody hates change. Week 1-4 of a UI overhaul, everyone hates it. It's all different and you have to find the stuff you want again. Once you figure it out you stop caring and usually whatever new/optimized feature gets a jump in usage, which is why they made a new UI in the first place. "
]
}
|
[] |
[] |
[
[]
] |
||
2v98t7
|
You're on a train and it crashes. Is it better to be in a forward facing or a rear facing seat?
|
askscience
|
http://www.reddit.com/r/askscience/comments/2v98t7/youre_on_a_train_and_it_crashes_is_it_better_to/
|
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"It's better to be facing backwards (this applies in planes as well).\n\nEither way, you're basically going to be decelerating instantaneously. The difference is where the force is applied. When facing backwards, the force is distributed across your entire back and it keeps all of your body parts held in stable positions. When facing forwards, assuming you aren't strapped in in any way, it's much more likely that your initial impact would be on a very small area, such as your face, the top of your head, or a limb. Even if you were to be strapped in, the force is being distributed over a much smaller area than if you're facing backwards, and your head would also snap forward (and likely back again), causing whiplash, a concussion, or worse.\n\nEdit: The primary reason that plane seats are oriented towards the front is just because passengers prefer that. Plane accidents are rare enough that this sort of thing isn't a big enough issue to attract public attention, but perceived discomfort is.",
"[This video shows a railcar impact test with both positions.](_URL_2_)\n\nIt is from [this tech report](_URL_1_) from the US DoT (PDF link is a bit down the page). Recorded peak loads on the crash dummies indicate that upper neck tension/compression force (Fz), upper neck shear force (Fx), and upper neck flexion/extension moment (My) were all less severe when tested in the rear-facing seats.\n\nMore crashworthiness tests can be found on the Volpe website: _URL_0_",
"Big misconception here in addition to the distribution of forces arguments. The more firmly you are attached to the vehicle, the less instantaneous your deceleration. You will start slowing down as soon as the vehicle does. If you are loosely attached to the vehicle (including having to move forward to meet your seatbelt) the vehicle has been slowing down while you are still moving at the original speed. Once you hit the seatbelt, seat in front of you, wall, windshield etc you now have less time available to you to come to rest which means a larger force must be exerted for the same impulse.\nEDIT: I guess I didn't make it clear. When you are facing backward you are essentially firmly attached to the vehicle.",
"Not sure if it's worth pointing out that in ~~many~~*some* cases of major train collisions, the impact comes from the rear: consider a train at rest or near-rest being hit from behind.\n\nIn those cases, in the carriages affected, G-forces within the same order of magnitude would be experienced but in reverse: passengers thrust backwards in relation to the seats.",
"\nRear facing, this is why we recommend children under 2 (even if their legs are too long) should stay in a rear facing seat as long as possible",
"Definitely facing rearward. Assuming your train seats have head rests, your entire body is supported during a crash as opposed to having most of the force concentrated on your seatbelt (or even worse - rocketing to the front of the train) so you are far less likely to receive an injury. \n\nP.S. Instant deceleration is impossible, even if your train runs into an indestructible surface (the forward carriage would collapse under the impact like the crumble zone of a car.) ",
"Many people are making the assumption that one is better than the other, and that's simply not true. As an engineer who does this for a living, let me tell you: \n\nIt's entirely contingent on the surroundings. People are surprisingly resilient. Someone wearing a lap belt in a forward facing seat can hit his own knees and still fare very well in a crash. If you add a table, the whole game changes. Face smashing on the table is always a bad situation. \n\nFacing backwards, you have this huge issue that everyone seems to forget: whiplash. The seat has to be perfect to prevent it. Now people are very diverse, and different heights and proportions have to be accounted for. Someone's entire head must be supported in a crash situation. So there must be deploy able headrests that adjust to the height of the occupant. There cannot be a gap between the headrests and the seat back, or else you get the same problem, as the shoulders will slip into the gap and snap a neck. \n\nAgain, with all that said, it is entirely contingent on the configuration of seats. ",
"As someone who works on trains and train cars, your biggest concern in a train crash is not which way you are seated, but whether your train car stays on the track.\n\nThe wheels of a train car are held on by gravity, meaning the car itself is just resting on top of the trucks ( the part that has the bolster, wheels, brake rigging, and and motors.) In a even low speed crashes if the wheels come off the rail, the drag of the wheels on the dirt and ties can cause the truck to be ripped from under the car. In a high speed collision this is often a chain reaction, and once the truck is gone, the car itself is no longer being forced to travel in the direction of the track and can start to go to either side, and if the train behind the car is still on the track it will begin to push the car around, which can lead to rolling or even pulling more cars off with it. It is not uncommon even to find cars on their sides in low speed collisions, and almost a certainty in a high speed collision. When your train car is upsidedown or traveling sideways, it doesn't matter which way you are facing.\n\nSrc: Iama rail car mechanic.",
"if the ONLY thing you had to worry about in a crash was your own fast deceleration, then backwards facing seats are the way to go. unfortunately in reality, because all sorts of small things, dishes, devices, garbage and such are not nailed down, and will go flying forward in the car at whatever speed it was you crashed, front facing seats will offer you much better protection overall. and remember to buckle up.",
"I was in a train crash once actually, and I was in a bed on a night train. Forward facing. I was hurled across the cabin, right into the other guy who was pressed with his back to the wall.\n\nI had a few small bruises and a dented toe (which took most of the impact), partly because knowing what was happening, I put my arms in front of my face. My opponent looked really bad. Must have been between a wall and a few bones of mine.\n\nSo which is better depends a lot on the circumstances.",
"Follow up question: what is more likely on a train, a head on collision with something (which is what everyone seems to be discussing here) or the train de-railing? Then, if the answer is de-railing, does that change the answer?",
"Facing backwards. Duh. Hounding have to be a scientist to know that. Just think. Would you rather be trust forward into a seat belt at 200 miles an hour and have all the pressure be concentrated on one strap or have it evenly distributed on your entire back? I mean all you have to do is imagine it man. Which would hurt more? A strap or a padded seat? The option that you can imagine hurting less is your correct answer. "
]
}
|
[] |
[] |
[
[],
[
"http://www.volpe.dot.gov/infrastructure-systems-and-technology/structures-and-dynamics/rail-equipment-crashworthiness",
"http://ntlsearch.bts.gov/tris/record/ntl/19478.html",
"https://www.youtube.com/watch?v=naBn3hHGqVE"
],
[],
[],
[],
[],
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||
3jb93h
|
How does a developing embryo know which side is left and which is right?
|
Today I heard about *Situs Inversus*, a disorder in which the internal organs are reversed left/right, and started wondering: how do the embryos know which side is which to begin with in the first place? Why isn't this random, with half the population one way and one the other way?
[Wikipedia mentions some proteins are different on the different sides which signals the necessary development](_URL_1_), but how did *they* get separated like that in an appropriate way?
As a physicist I'm supposed to be afraid of anything that violates [parity symmetry](_URL_0_) other than beta decay, but I doubt that's involved.
|
askscience
|
https://www.reddit.com/r/askscience/comments/3jb93h/how_does_a_developing_embryo_know_which_side_is/
|
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"It happens because cilia beat asymmetrically, and ciliary motion of fetal cells therefore creates an asymmetric flow of fluid around the fetus, thus creating asymmetry to chemical signaling during fetal development. Situs inversus is caused by ciliary dismotility.",
"Simple breakdown: The embryo begins by developing symmetrically into a flat disc with a node near one end. Near the node we observe cilliated cells (due to signaling concentrations)\n\nCilia, due to their structure rotate in a specific direction. Therefore this clump of cells create a current that researchers observed creates a current of embryonic fluid that flows more or less from right to left. This causes signaling molecules in the embryonic fluid to preferentially effect cells on the left. Once the cells on one side begin developing a sided-ness it inhibits the development of the other side from developing the same sided-ness.\n\nIn case this article hasn't already been linked it does a pretty good job of describing much of what is known about this particular process.\n_URL_0_",
"My roommate a while back was a biochem grad student, he was studying mRNA localization. While I can't confirm that what the other posts about cilia and whatnot are correct, I can offer insight into a slightly earlier stage (take with a grain of salt, I wasn't the one doing the research).\n\nHis research was into mRNA localization in the oocytes of African clawed frogs. Basically what I learned from his research was that mRNAs are localized in particular portions of the original cell either to inhibit or encourage protein synthesis. The areas which the cell localizes these mRNAs to is determined by several mechanisms, some more passive than others, that are oriented between each other and along an axis determined by the location of fertilization. As the cell divides and the embryo grows this localization is transferred from one cell to the next promoting differentiation.\n\nAgain, take this with a grain of salt as it wasn't my research, and it was so long ago. If anyone can confirm, deny, or correct me then that would be much appreciated."
]
}
|
[] |
[
"https://en.wikipedia.org/wiki/Parity_(physics\\)",
"https://en.wikipedia.org/wiki/Situs_solitus"
] |
[
[],
[
"http://cshperspectives.cshlp.org/content/1/1/a000802.full"
],
[]
] |
|
mzhgh
|
How have we evolved the ability to smell chemicals
from such geographically widespread plants?
|
Cloves come from Indonesia. We can smell Eugenol, which is the dominant aroma compound in cloves.
Vanilla comes from Mexico and Central America. We can smell Vanillin, which is the dominant aroma compound in vanilla.
Anise comes from the Mediterranean. We can smell Anisole, which is the dominant aroma compound in anise.
And so on and so forth.
Yet humans arose in Africa, and would have never had any direct experience with any of these aromas in the early days of humanity.
Does this mean that our evolutionary ancestors basically traveled the whole world, even before the breakup of Pangaea (seeing as we can smell things unique to the Eastern and Western hemispheres), evolving the ability to smell new things as they went?
And if that's the case, does it stand to reason that different creatures with different evolutionary lineages have *vastly* different abilities to smell different things, based on where their ancestors traveled?
|
askscience
|
http://www.reddit.com/r/askscience/comments/mzhgh/how_have_we_evolved_the_ability_to_smell/
|
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"I'm sure someone who has more expertise can come in a give a better answer. The chemoreceptors in our nose bind to and detect certain chemical bonds, stimulating the neuro signal that our olfactory bulb then processes and creates the 'smell' we smell. There's some debate on this, but apparently we only have around 200 unique receptors. However molecules will activate more than one receptor and substances will have a combination of detectable molecules. Our brain interprets the different patterns of the activation of different. So it's not like we have a receptor for every single smell producing substance. For example, here in this paper the Eugenol receptor in mice also responds to many other molecules: _URL_0_\n\nYou do bring up and interesting point about the genetic variability of the receptors with geographic location. I don't know if this has been investigated, but my guess is that certain populations' smell receptors would differ from each other in subtle ways. ",
"I'm sure someone who has more expertise can come in a give a better answer. The chemoreceptors in our nose bind to and detect certain chemical bonds, stimulating the neuro signal that our olfactory bulb then processes and creates the 'smell' we smell. There's some debate on this, but apparently we only have around 200 unique receptors. However molecules will activate more than one receptor and substances will have a combination of detectable molecules. Our brain interprets the different patterns of the activation of different. So it's not like we have a receptor for every single smell producing substance. For example, here in this paper the Eugenol receptor in mice also responds to many other molecules: _URL_0_\n\nYou do bring up and interesting point about the genetic variability of the receptors with geographic location. I don't know if this has been investigated, but my guess is that certain populations' smell receptors would differ from each other in subtle ways. "
]
}
|
[] |
[] |
[
[
"http://pubs.acs.org/doi/abs/10.1021/bi1017396"
],
[
"http://pubs.acs.org/doi/abs/10.1021/bi1017396"
]
] |
|
26etgm
|
Why does food cook? Why doesn't it change to a liquid /gas?
|
askscience
|
http://www.reddit.com/r/askscience/comments/26etgm/why_does_food_cook_why_doesnt_it_change_to_a/
|
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"chqstb2"
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"It doesn't get hot enough to turn to liquid or gas. The thing about food (depending on what it is) is that it's a very complex mixture of proteins and carbohydrates. The cooking process gives enough energy to mess with their structure, which is the cooking process: breaking bonds and disrupting non-covalent interactions. However, it doesn't give enough energy to liquefy most foods since this threshold is much higher."
]
}
|
[] |
[] |
[
[]
] |
||
1wb701
|
At what point on a trip up a space elevator would you begin feeling weightless?
|
So let's say there's a real space elevator, hypothetically. And you're riding up it to geostationary orbit. What do you feel on the way up? Are there any notable sensations other than due to the climbing of the elevator?
Once you hit the normal altitude of Low Earth Orbit, say 300km, if you jumped off the elevator would you just fall straight down? At what point on the way up do you have enough horizontal velocity to be in a stable (though highly eccentric) orbit if you jump off the elevator.
At what point on the way up do you start feeling weightless? It seems like the inside of a space elevator cable car would be a very strange reference frame to be in.
|
askscience
|
http://www.reddit.com/r/askscience/comments/1wb701/at_what_point_on_a_trip_up_a_space_elevator_would/
|
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"It's a misconception that people in orbit experience weightlessness due to their distance from Earth causing reduced gravity. In fact, objects in orbit actually experience 90% of Earth's gravity. What actually causes weightlessness in orbit is their horizontal movement. They're basically constantly falling towards the ground, but because the ground is curved, it's constantly moving away from them, causing them to be in and endless free fall.\n\nSo to answer your question, there is no point on a trip up a space elevator that you would feel weightless.\n\nEdit: [This xkcd](_URL_0_) helps to explain how orbital weightlessness works.",
"An object in geo-stationaary orbit can hover over the same spot on the earth without falling because it is at a distance that gravity has gotten weak enough and centrifugal force (or fundamentally, the pod's own inertia) has gotten strong enough that the two cancel, leaving a net force of zero in the non-inertial reference frame of the rotating earth. You can therefore experience weightless without falling when you are in geo-stationary orbit. \n\nNow, when you are riding the space elevator, gravity is getting progressively weaker, and the centrifugal force is getting progressively stronger (because you are traversing a greater circumference with the earth in the same period), so that the net force on your body *gradually* decreases to zero. So there is no point where weightlessness switches on. Rather, you gradually feel more weightless throughout the entire ride (assuming the elevator is traveling at a constant speed so you don't have to factor in the acceleration of the elevator).\n\n > Once you hit the normal altitude of Low Earth Orbit, say 300km, if you jumped off the elevator would you just fall straight down?\n\nYes (well not \"straight\" down). If you are below the geo-stationary altitude and have a tangential speed such that you are fixed over one spot on earth's surface, you are not going fast enough to stay in orbit. You would fall to the earth in a spiraling sub-orbital trajectory if you jumped off the elevator.\n\nNote that I'm not saying that there's little gravity in geo-stationary orbit or that the lack of gravity is what keeps you in orbit. It's still your inertia (because of your incredible sideways speed) that keeps you in orbit. But the gravity has weakened enough that you can go slow enough to stay in line with one spot on earth's surface as it rotates around.\n\nEDIT: fixed typos.",
"towards the end, but not for the reason most people are saying; although they might be answering the spirit of the question. to get into space in a timely manner, you should be accelerating most of the way. once you were close to the end, it would slow quickly enough that you would be floating weightlessly in the box. the length of time that you were weightless would be decided by the top speed of the elevator.",
"It's not too difficult to work this out mathematically. If you put the elevator into a rotating reference frame, rotating at the same rate as the Earth, then you can work out the centrifugal acceleration as a function of height. The centrifugal acceleration will gradually counter the gravitational acceleration, until, at geostationary orbit, you are completely weightless.\n\nI'm not going to work out the cross products explicitly here, because it's messy, but with the space elevator placed on the equator (which it would have to be if you want to use it to reach geostationary orbit), your centrifugal acceleration would increase as Ca=w^2 h, where w is the Earth's angular velocity, and h is your height (in this case above the Earth's centre, rather than the surface, as this would be the origin of our rotating reference frame). This means that the centrifugal acceleration would increase linearly with height.\n\nThis is not the full picture, though, because the gravitational acceleration decreases as you get higher, as well. The acceleration will decrease with the square of your height, and go like Ga = g*(r^2 / h^2 ), where g is your acceleration on the surface, r is the radius of the earth, and h is your height above the earth's centre. If you subtract the centrifugal acceleration from the gravitational acceleration, you will get a good picture of how much gravity you will feel at a certain height.\n\nEven this is still not the full picture, though. As you're moving upwards, the elevator will have to counteract the coriolis force. You can think of this as the elevator increasing your orbital velocity; if you're circling the Earth in the same time, but at a larger radius, you will need a higher speed to do so. You will not naturally gain this speed just from being higher up, so the elevator will have to push you. This acceleration you will feel like an additional gravity, sideways in the elevator car. How much you accelerate, depends on how quickly you're ascending (if you're gaining radius at a higher rate, you'll have to gain orbital velocity at a higher rate). I'm not going to work out the cross products explicitly here, either, but this means you will also feel an acceleration in the westerly direction, equal to Ca = 2wv, where v is your velocity. This means that the coriolis force will only really start to be noticeable at speeds over 10 km/s. I have no idea how fast a space elevator would go, but this seems like a very high speed to me, so I guess we can discount the Coriolis force.\n\nI've plotted the gravity felt versus height on this plot: _URL_0_ . The y-axis is gravity felt in terms of Earth gravity (where 1 is surface gravity, 0 is weightless), and the x-axis is kilometres above the surface of the Earth (not the centre this time). The upper straight line is Mars gravity, while the lower straight line is Moon gravity. As you can see, there is no point where one suddenly finds oneself weightless, but rather you would find yourself lighter and lighter as you ascended. An interesting point is that when you reach what is generally defined as \"space\" (100 km), you would hardly even have started to feel a change in gravity."
]
}
|
[] |
[] |
[
[
"http://what-if.xkcd.com/58/"
],
[],
[],
[
"http://fooplot.com/plot/4yobvncx8o"
]
] |
|
11mfgc
|
When we grow up, where do the atoms find their way into our growing bodies? And is it possible those atoms used to be part of some other human before?
|
Sorry for possible grammar errors I'm not a native english speaker. But as far as I understand energy cannot be created nor cease to exist, so the atoms which everything is made of must be somehow recycled?
|
askscience
|
http://www.reddit.com/r/askscience/comments/11mfgc/when_we_grow_up_where_do_the_atoms_find_their_way/
|
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"Not really a serious, detailed answer, but the atoms find their way into our growing bodies, mostly through food... And yes it is possible that some of the atoms in your body to have been in another human being. I don't know how likely that is but even that is statistically calculable.",
"Statistically it is highly unlikely that atoms of your body did not belong to another human.\n\nHowever, you cannot label atoms of the same type. If I give you two boxes and each contains a hydrogen atom in its ground-state. You cannot tell if or when the atoms just exchange places or if one of the hydrogen atoms was taken from outside.\n\nApart from this problem to differnetiate between atoms, we know they move around through many different processes (you can track that for example by introducing a different isotope and see how it travels through a system). And we also know that human bodies are composed of a huge number of atoms (mind boggingly huge).\n\nIn fact, (again statistically speaking, atoms cannot be properly distinguished and making a few silly assumptions) it is very likely that with each breath you take you inhale atoms that were breathed by Socrates (or any other famous person from the past). Even more, you probably also breath atoms that he exhaled with his last breath (not just one from the many breaths he took in his lifetime).\n\n_URL_0_"
]
}
|
[] |
[] |
[
[],
[
"http://www.hk-phy.org/articles/caesar/caesar_e.html"
]
] |
|
57venf
|
what does the chairman of the senate budget committee do? what authority do they have that other senators don't?
|
explainlikeimfive
|
https://www.reddit.com/r/explainlikeimfive/comments/57venf/eli5what_does_the_chairman_of_the_senate_budget/
|
{
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"text": [
"Proposed legislation is typically sent to the committee that it falls under. The committee then holds investigations and actually crafts the legislation. Once the committee approves it, it goes to the floor for a vote are further tweaks. Basically they are the head person of the group that gets to write the first draft of the annual budget."
]
}
|
[] |
[] |
[
[]
] |
||
29gso2
|
How does specific heat affect heat transfer between objects?
|
If material A is an object at a temperature t1 with a specific heat of u1, and material B is a liquid at temperature t2 and specific heat u2, such that t1 > t2 and u1 < < u2, if A was immersed in B , would material A be cooled below temperature t2 (even for only a moment) because of the lesser energy required to cool it or would the two substances end up at the same temperature no matter what the specific heats?
|
askscience
|
http://www.reddit.com/r/askscience/comments/29gso2/how_does_specific_heat_affect_heat_transfer/
|
{
"a_id": [
"ciktmvr"
],
"score": [
3
],
"text": [
"the two materials would move towards equilibrium. the hotter material would always be hotter than the other, and vice versa, until they reach equilibrium.\nthe end temperature will therefore be between the two start temperatures, and the end temperature would depend upon the mass and specific heat capacity of each material.\neach would lose and gain heat according to Q=m*Cp*(t1-t1)\n"
]
}
|
[] |
[] |
[
[]
] |
|
54h2ma
|
is it better to brake hard to avoid in a car or apply firm braking
|
Say you can clearly see the the traffic is slowing extremely rapidly but you do have time to brake. What will provide the **best reduction in speed**, slam on brakes on braking as firmly as possible?
|
explainlikeimfive
|
https://www.reddit.com/r/explainlikeimfive/comments/54h2ma/eli5is_it_better_to_brake_hard_to_avoid_in_a_car/
|
{
"a_id": [
"d81se62",
"d81xjxa"
],
"score": [
2,
7
],
"text": [
"Depends on your car, road conditions and tires.\n\nIn many modern cars, antilock brakes are standard. So a panic stop where you slam on the brake pedal will engage the antilock system and automatically pulsate the braking to prevent skidding.\n\nOn a regular basis, panic stop braking is high risk and adds additional wear on the car. Gentle braking is safer and better for the vehicle.",
"the quickest way to slow down is the apply enough brakes to use 100% of the tire's traction.\n\nproblem is...you don't know where that limit is.\n\nif you brake 80% of tire traction, you're just leaving some power on the table.\n\nif you brake with 120% of tire traction, you'll lock up the tire and take longer \n\nantilock brakes try to counter this by detecting after you've locked up the brakes and dialing the braking power down by pulsing the brake pedal. almost all the time, this is fine. but this is still a REactive solution rather than a PROactive solution. \n\nthe best way is to quickly apply brake and feel the weight of the car shift forward towards the front wheels, then progressively apply more pedal pressure until you reach the limit, then back off just a tad. \n\nthe first stage is known as weight shift. the available traction of the tire is dependent on how much weight pressure there is on the tire. when you decrease velocity from cruising or acceleration, the weight of the car shifts forward, putting more weight on the front tires. this means you have less available traction when you're cruising. you have more available traction when you're already braking. you want to load the front tires with weight before you go onto the second stage of increasing brake pressure. \n\nduring the second stage, you'll increase brake pressure until you reach the limit of the tire traction. if you go over the limit, you'll know by either the Antilock Brake System kicking in and vibrating the brake pedal, or in a nonABS car, the front tires will lock up and you'll hear squeeching and smell tire smoke. if that happens, you'll reduce the pressure slightly. since your leg muscles are only capable of macro-adjustments, the recommended method is to hold your leg muscle at same pressure and curl your toes until the ABS stops vibrating, or the tires stops locking up. \n\nthe only way you'll know how to do this is to learn it in a controlled environment and practice it over and over. this is best done in defensive driving schools or at autocross car training events. you will have to on the fly adapt to varying road conditions that will dynamically change the level of traction available to your front tires. there are many many variables such as:\n\n1) road surface type. concrete vs asphalt vs dirt\n\n2) debris on road. rain, snow, sand, gravel, oil, ice\n\n3) temperature of the road. asphalt grips better than concrete not only because of the surface but because it's black and higher temperature. \n\n4) flatness of the road. cracks, potholes, patches all decrease the available traction\n\n5) your tire tread depth and compound and tire temperature. cold tires have less traction than hot tires. road tires reach nominal temps after 15minutes of at-speed driving. \n\nawareness of all of these variables pushes you to be more ready to apply the correct braking pressure."
]
}
|
[] |
[] |
[
[],
[]
] |
|
1m4nkz
|
Were Warbonds a good investment?
|
Many governments sold War Bonds as way of financing wars. The most famous example is probably during the First and Second World War. Were these bonds ever a good investment which turned a profit for investors or did they only have patriotic value?
|
AskHistorians
|
http://www.reddit.com/r/AskHistorians/comments/1m4nkz/were_warbonds_a_good_investment/
|
{
"a_id": [
"cc5w23q",
"cc5zg02"
],
"score": [
3,
2
],
"text": [
"Adding on to OP's question, what were the interest rates on various war bonds issued by different countries? Did anyone \"hedge\" their war bonds? Were war bond purchases usually limited to citizens of that country? if not, have there ever been prominent cases of citizens from one country buying the opposing country's war bonds (for example, someone in occupied France who opposed the occupation buying British war bonds)?",
"Churchill claims, in his memoirs, to have fought \"a 3% war\". The Liberty bonds issued by the US in 1917-18 varied from 3.5% to 4.25%; the last one, however, was repaid in no-longer-gold-standard dollars and was probably a major loss for the bondholders in terms of purchasing power. The war debts of Germany (in both wars) were, I believe, simply repudiated; and of course, just try to get back your money from the Tsar. \n\nEven for the UK/US bonds, three or four percent does not seem like a very good rate, considering that there was presumably some reasonable chance that the other guys were going to win and you'd never get your money back. Compared to putting the same money in the stock market, it was probably rather a bad investment. It seems to me that there was a \"patriotic discount\", that the government could borrow at a lower rate \"to support the troops\" (in modern parlance) than it could have done in peacetime. \n\nThat said, a profit smaller than you might have made in a different investment is not the same as a loss. Most of the investors in the victor nations prseumably got their money back and a profit; just not as large as they would have made elsewhere. "
]
}
|
[] |
[] |
[
[],
[]
] |
|
rzv45
|
Are there any two foods/edible materials that are harmless when consumed separately and dangerous when consumed together?
|
This was somewhat inspired by a friend's belief that she would explode if she ate Mentos and Diet Coke in quick succession. Having empirically showed that this is untrue, are there any foods/drinks/other materials which are safe to consume on their own, but would have side effects if consumed together?
|
askscience
|
http://www.reddit.com/r/askscience/comments/rzv45/are_there_any_two_foodsedible_materials_that_are/
|
{
"a_id": [
"c49ylby",
"c49zq8l"
],
"score": [
5,
5
],
"text": [
"Not so much with food, since food tends to mostly be made of the same types of chemicals. Certain drug combinations, like Tylenol and alcohol, can do more damage together than either would alone, although your body can usually repair this damage if it's not a combination you take very often.",
"Some drug and food combinations are dangerous. MAO-inhibitors, a class of drugs used to treat depression, inhibit an endogenous enzyme (MAO) that otherwise breaks down chemicals present in foods and other drugs. Tyromine is one such chemical -- an amino acid present in many foods (especially fermented foods) which can be dangerous without the regulating effect of MAO. \n\n_URL_1_\n\n_URL_0_\n\nAnother example that I'm familiar with is grapefruit, which can increase the effects of some drugs, potentially making them dangerous. \n\n_URL_2_\n\n"
]
}
|
[] |
[] |
[
[],
[
"http://www.mayoclinic.com/health/maois/HQ01575",
"http://en.wikipedia.org/wiki/Monoamine_oxidase_inhibitor#Interactions",
"http://en.wikipedia.org/wiki/Grapefruit#Drug_interactions"
]
] |
|
3oi0p0
|
why does drinking a liquid such as a dry wine leave your mouth feeling dry even though it's a liquid?
|
explainlikeimfive
|
https://www.reddit.com/r/explainlikeimfive/comments/3oi0p0/eli5_why_does_drinking_a_liquid_such_as_a_dry/
|
{
"a_id": [
"cvxd47s",
"cvxex5z"
],
"score": [
5,
2
],
"text": [
"With red wine, you are feeling a chemical called *tannin* which gives the illusion of a dry feeling.",
"The tannins in wine are an astringent. The property of an astringent (when the word is used for foods) is that it cause the proteins in the salivary glands to bind up. so...you stop kicking out saliva, and....your mouth is no longer as wet as it was. The second you swallow, the moisture in your mouth is based on saliva, not the stuff you just had in there. It does not \"stay wet\" (e.g. when you wet a piece of paper it absorbs water), it either has moisture in it or it doesn't and this requires constant moisture production in the form of saliva."
]
}
|
[] |
[] |
[
[],
[]
] |
||
39j2zb
|
if i am not supposed to peel off a scab how come all my instincts are telling me to do it
|
explainlikeimfive
|
http://www.reddit.com/r/explainlikeimfive/comments/39j2zb/eli5_if_i_am_not_supposed_to_peel_off_a_scab_how/
|
{
"a_id": [
"cs3th2i"
],
"score": [
30
],
"text": [
"Because your scab has healed at the edges, meaning your body, right at those points, is going \"Hey there's some junk on this healthy skin, get it off!\" so you have the instinct to rip at it (or scratch at it).\n\nThe problem is, it's *only* healed at the edges, and the scab is a big whole thing that's attached, so you can't JUST pull off the part at the edges. But your body is too dumb to know that."
]
}
|
[] |
[] |
[
[]
] |
||
335p8w
|
how do antibiotics kill unwanted bacteria but not the body's own cells?
|
I know about enzymes and such in a basic sense, but the fact that an antibiotic actually *works* still doesn't quite make sense to me. Wouldn't we need a specifically engineered antibiotic for each strain of bacteria? Why does the antibiotic only harm bacteria?
|
explainlikeimfive
|
http://www.reddit.com/r/explainlikeimfive/comments/335p8w/eli5_how_do_antibiotics_kill_unwanted_bacteria/
|
{
"a_id": [
"cqhrbz2",
"cqhs858",
"cqhtg4o"
],
"score": [
2,
15,
2
],
"text": [
"Antibiotics have many different mechanisms, but essentially, they take advantage of how bacteria are different from human (or more generally, animal or even eukaryotic in some cases) cells. \n\nA famous example is Penicillin. It works by damaging the bacteria's ability to maintain it's peptidoglycan cell wall. Humans don't have such a cell wall, so it doesn't harm us.",
"This principle is called \"selective toxicity\". \n\nIt utilises the fact that bacterial cells are different from human/animal cells. Specifically, they have different biochemistry, different anatomy, etc.\n\nFor example, a very popular group of antibiotics called beta-lactams (an example is penicillin, but there are lots of synthetic variants) work by blocking the biochemical pathway that builds the bacterial cell wall. Because the bacteria cannot maintain or extend their cell walls, eventually the wall degrades and the bacteria die.\n\nOther antibiotics affect different chemical processes. For example, the antibiotic tetracycline, blocks the process that bacteria use to translate their DNA code into protein manufacture. The ribosomes, the molecular machines that build proteins, are different between bacteria and mammals, so the mammal ribosomes are less affected (also bacteria actively pump tetracycline from outside to insude because the tetracycline tricks the bacterial molecular pumps which absorb nutrients, so the bacterial ribosomes get a much bigger dose than mammal cells, which don't have pumps which accept tetracycline). The other interesting thing about tetracycline is that it doesn't kill bacteria. It just stops them, or slows down, reproducing because it slows down protein production. This is still useful, because it gives the immune system time to catch up.",
"There are structural differences in the cells - most bacteria have cell walls while we humans do not. Penicillins prevent the proper linking of the cell wall components, making the bacteria very vulnerable to lysis (bursting) when there's an osmotic imbalance"
]
}
|
[] |
[] |
[
[],
[],
[]
] |
|
3nitzk
|
how is stephen colbert a character? what is different between stephen colbert and "stephen colbert"?
|
explainlikeimfive
|
https://www.reddit.com/r/explainlikeimfive/comments/3nitzk/eli5how_is_stephen_colbert_a_character_what_is/
|
{
"a_id": [
"cvoh5ac",
"cvoh61k",
"cvohg26",
"cvojyc2"
],
"score": [
11,
4,
2,
3
],
"text": [
"Stephen Colbert played a character by the same name on his Comedy Central show \"The Colbert Report\". The fictional Colbert was a parody of the kind of personality-driven opinion shows common on nighttime cable news networks.\n\nWhile that was a very popular character that was appropriate for his cable show, it wouldn't be appropriate for a host of a major network late night talk show. So, what you're seeing there is Stephen Colbert, the comedian, and not the character he previously played of the same name.",
"Stephen Colbert the actor had a show *The Colbert Report*, on which he played a twisted version of himself. The big difference is that their politics were considerably different -- Colbert the pundit was a conservative, while Colbert the actor is pretty damn liberal. They also went to different universities -- Colbert the actor is a graduate of Northwestern, while Colbert the pundit talked about going to Dartmouth.\n\nBoth were Catholic and were huge Tolkien fans.",
"The stephen colbert who you was in colbert report was a character. In reality he is not dumb and conservative and his views are total opposite on colbert report than his real views.",
"It's sort of like how Will Smith in Fresh Prince was a character played by the actor of the same name. Certain elements may or may not play in, but they are otherwise a fictional representation of a person with the same name."
]
}
|
[] |
[] |
[
[],
[],
[],
[]
] |
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