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you 're telling a friend an amazing story , and you just get to the best part when suddenly he interrupts , `` the alien and i , '' not `` me and the alien . '' most of us would probably be annoyed , but aside from the rude interruption , does your friend have a point ? was your sentence actually grammatically incorrect ? and if he still understood it , why does it even matter ? from the point of view of linguistics , grammar is a set of patterns for how words are put together to form phrases or clauses , whether spoken or in writing . different languages have different patterns . in english , the subject normally comes first , followed by the verb , and then the object , while in japanese and many other languages , the order is subject , object , verb . some scholars have tried to identify patterns common to all languages , but apart from some basic features , like having nouns or verbs , few of these so-called linguistic universals have been found . and while any language needs consistent patterns to function , the study of these patterns opens up an ongoing debate between two positions known as prescriptivism and descriptivism . grossly simplified , prescriptivists think a given language should follow consistent rules , while descriptivists see variation and adaptation as a natural and necessary part of language . for much of history , the vast majority of language was spoken . but as people became more interconnected and writing gained importance , written language was standardized to allow broader communication and ensure that people in different parts of a realm could understand each other . in many languages , this standard form came to be considered the only proper one , despite being derived from just one of many spoken varieties , usually that of the people in power . language purists worked to establish and propagate this standard by detailing a set of rules that reflected the established grammar of their times . and rules for written grammar were applied to spoken language , as well . speech patterns that deviated from the written rules were considered corruptions , or signs of low social status , and many people who had grown up speaking in these ways were forced to adopt the standardized form . more recently , however , linguists have understood that speech is a separate phenomenon from writing with its own regularities and patterns . most of us learn to speak at such an early age that we do n't even remember it . we form our spoken repertoire through unconscious habits , not memorized rules . and because speech also uses mood and intonation for meaning , its structure is often more flexible , adapting to the needs of speakers and listeners . this could mean avoiding complex clauses that are hard to parse in real time , making changes to avoid awkward pronounciation , or removing sounds to make speech faster . the linguistic approach that tries to understand and map such differences without dictating correct ones is known as descriptivism . rather than deciding how language should be used , it describes how people actually use it , and tracks the innovations they come up with in the process . but while the debate between prescriptivism and descriptivism continues , the two are not mutually exclusive . at its best , prescriptivism is useful for informing people about the most common established patterns at a given point in time . this is important , not only for formal contexts , but it also makes communication easier between non-native speakers from different backgrounds . descriptivism , on the other hand , gives us insight into how our minds work and the instinctive ways in which we structure our view of the world . ultimately , grammar is best thought of as a set of linguistic habits that are constantly being negotiated and reinvented by the entire group of language users . like language itself , it 's a wonderful and complex fabric woven through the contributions of speakers and listeners , writers and readers , prescriptivists and descriptivists , from both near and far .
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rather than deciding how language should be used , it describes how people actually use it , and tracks the innovations they come up with in the process . but while the debate between prescriptivism and descriptivism continues , the two are not mutually exclusive . at its best , prescriptivism is useful for informing people about the most common established patterns at a given point in time .
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can you think of any ways or situations in which prescriptivism is unhelpful ?
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( music ) quick ! what 's common between beef burgers , baseball training and auto mufflers ? tough question . let 's ask it another way . what 's the common factor between mcdonald 's , d-bat and meineke ? you may know the answer if , along with a big mac , you 've absorbed a fragment of the romantic story of ray kroc . he 's the salesman that created what became the world 's biggest fast food chain . he did it by making a deal with a couple of men called the mcdonalds . brothers they were , owners of a small restaurant chain , and the deal was , he could use their brand name and their methods . then he invited small entrepreneurs to open mcdonald 's , that they 'd run as operators , with an ownership state . very different than the business model where mom and pop stores have full ownership , but no similar support . all the examples in my opening question are a franchise operation . kroc is sometimes credited with inventing franchising , and so is isaac singer , the sewing machine magnate . not so . the real genesis of franchising was not in stitches or beef , it was in beauty . martha matilda harper was a canadian-born maid . she made the beds , cleaned house , did the shopping . in the employment of a doctor 's family in ontario , she acquired a secret formula for shampoo , one more scientifically based than the quackeries advertized every day in the newspapers . the kindly doctor also taught the maturing young woman the elements of physiology . martha had a secret ambition to go along with the secret formula : a determination to run her own business . by 1888 , serving as a maid in rochester , new york , she saved enough money -- 360 dollars -- to think of opening a public hairdressing salon . but before she could realize her dream , two blows fell . she became sick , and collapsed from exhaustion . mrs. helen smith , a healing practitioner of the christian science faith , was summoned to her bedside . the two women prayed , and martha recovered . no sooner was she better then she was told , `` oh no , you ca n't rent the place you 've eyed . '' you see , her venture was to be the first public hairdressing salon . a woman in business was shocking enough then . only 17 percent of the workforce in 1890 was female , but a woman carrying out hairdressing and skincare in a public place ? why , it was sure to invite a scandal . martha spent some of her savings on a lawyer , and won her case . she proudly displayed on the door of her new her salon a photograph of the barely five-foot martha as rapunzel , with hair down to her feet , but glowing with good health . her sickness , too , had proved a boon . her ambition was now propelled by christian science values . the harper method , as she came to call her services , was as much about servicing the soul as it was about cutting hair . in the therapeutic serenity of her salon , she taught that every person could glow with the kind of beauty she had , if spiritually whole and physically obedient to what she called `` the laws of cleanliness , nourishment , exercise and breathing . '' she was very practical about it . she even designed the first reclining shampoo chair , though she neglected to patent the invention . martha 's salon was a huge success . celebrities came from out of town to experience the harper method . they enjoyed the service so much that they urged her to set up a salon in their cities . and this is where martha 's ethical sense inspired her crowning innovation . instead of commissioning agents , as other innovators had done , from 1891 , she installed working-class women just like herself in salons exactly like hers , dedicated to her philosophy and her products . but these new employees were not provided a salary by martha . the women in what became a satellite network of 500 salons in america , and then europe and central america and asia , actually owned the harper 's salons . what was good enough in the nineteenth century for suffragette campaigners like susan b. anthony and was good enough in the twentieth century for woodrow wilson , calvin and grace coolidge , jacqueline kennedy , helen hayes and ladybird johnson must be good enough for the rest of the world . today , only the harper method founder 's shop remains in rochester , new york , but martha 's legacy is manifold . her health and beauty treatments have been copied , and her business model is dominant . in fact , half of retail sales in america are through martha harper 's franchising idea . so the next time you enjoy a mcdonald 's hamburger or a good night 's rest at a days inn , think of martha . because these franchises might not be the same without her inventing the model , over a century ago .
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she was very practical about it . she even designed the first reclining shampoo chair , though she neglected to patent the invention . martha 's salon was a huge success .
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oops ! harper forgot to patent this invention :
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translator : andrea mcdonough reviewer : bedirhan cinar you might have heard that we 're running out of fresh water . this might sound strange to you because , if you live in a place where water flows freely from the tap or shower at any time , it sure does n't seem like a big deal . it 's just there , right ? wrong ! the only obvious thing about fresh water is how much we need it . because it 's essential to life , we need to think about it carefully . right now , at this very moment , some people , women and girls in particular , walk hours and miles per day to get fresh water , and even then , it may not be clean . every 15 seconds , a child dies due to water-born diseases . this is tragic ! the most compelling reasons to think about fresh water , therefore , have to do with what we might call the global common good . this is not something we normally think about , but it means recognizing how much fresh water matters for the flourishing of human and non-human life on earth now and in the future . how do we think about something as local as our faucets and as global as fresh water ? is there a connection between them ? many people assume that fresh water shortages are due to individual wastefulness : running the water while you brush your teeth , for example , or taking really long showers . most of us assume , therefore , that water shortages can be fixed by improving our personal habits : taking shorter showers or turning off the water while we brush our teeth . but , global fresh water scarcity neither starts nor ends in your shower . globally , domestic use of fresh water accounts for only 8 % of consumption , 8 % ! ! compare that to the 70 % that goes to agriculture and the 22 % that goes to industrial uses . now , hold up - you 're not off the hook ! individual habits are still part of the puzzle . you should still cultivate water virtue in your daily life , turn off the tap when you brush your teeth . but still , it 's true . taking shorter showers wo n't solve global problems , which is too bad . it would be much more straightforward and easier if virtuous , individual actions could do the trick . you 'd just stand there for 30 seconds less , and you 'd be done with that irksome , planet-saving task for the day . well , that 's not so much the case . agricultural and industrial patterns of water use need serious attention . how do our societies value water ? distribute it ? subsidize its use in agriculture ? incentivize its consumption or pollution ? these are all questions that stem from how we think about fresh water 's value . is it an economic commodity ? a human right ? a public good ? nobel prize winners , global water justice activists , transnational institutions like the united nations , and even the catholic church are at work on the issue . but , it 's tricky , too , because the business of water became very profitable in the 20th century . and profit is not the same thing as the common good . we need to figure out how to value fresh water as a public good , something that 's vital for human and non-human life , now and in the future . now that 's a virtuous , collective task that goes far beyond your shower .
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we need to figure out how to value fresh water as a public good , something that 's vital for human and non-human life , now and in the future . now that 's a virtuous , collective task that goes far beyond your shower .
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where water is concerned , what does peppard say is a virtuous task ?
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when the next general election rolls around , who will be eligible to show up at the polls and vote for the president of the united states ? it 's really pretty simple . if you are at least 18 years old , a citizen of the u.s. , and a resident of a state , you can vote , assuming , that is , you are not a felon . seems about right . after all , the united states prides itself on being a democracy , or a government in which the ultimate authority lies with the citizens of the nation . but it was not always this way . in 1789 , george washington won the electoral college with 100 % of the vote , but whose vote was it ? probably not yours . only 6 % of the entire united states population was allowed to vote at all . voting was a right that only white , male property owners were allowed to exercise . by the 1820s and 1830s , the american population was booming from the east coast into the western frontier . frontier farmers were resilient , self-reliant , and mostly ineligible to vote because they did not own land . as these new areas of the nation became states , they typically left out the property requirement for voting . leaders such as andrew jackson , the united state 's first common man president , promoted what he called universal suffrage . of course , by universal suffrage , jackson really meant universal white , male suffrage . all he emphasized was getting rid of the property requirement for voting , not expanding the vote beyond white men . by the 1850s , about 55 % of the adult population was eligible to vote in the u.s. , much better than 6 % , but far from everybody . then , in 1861 , the american civil war began largely over the issue of slavery and states ' rights in the united states . when it was all over , the u.s. ratified the 15th amendment , which promised that a person 's right to vote could not be denied based on race , color , or previous condition as a slave . this meant that black men , newly affirmed as citizens of the u.s. , would now be allowed to vote . of course , laws are far from reality . despite the promise of the 15th amendment , intimidation kept african-americans from exercising their voting rights . states passed laws that limited the rights of african-americans to vote , including things like literacy tests , which were rigged so that not even literate african-americans were allowed to pass , and poll taxes . so , despite the 15th amendment , by 1892 , only about 6 % of black men in mississippi were registered to vote . by 1960 , it was only 1 % . and , of course , women were still totally out of the national voting picture . it was n't until 1920 that the women 's suffrage movement won their 30-year battle , and the 19th amendment finally gave women the vote , well , white women . the restrictions on african-americans , including african-american women , remained . after world war ii , many americans began to question the state of u.s. democracy . how could a nation that fought for freedom and human rights abroad come home and deny suffrage based on race ? the modern civil rights movement began in the 1940s with those questions in mind . after years of sacrifice , bloodshed , and pain , the united states passed the voting rights act of 1965 , finally eliminating restrictions such as literacy tests and protecting the voting rights promised under the 15th amendment to the constitution . now , any citizen over the age of 21 could vote . all seemed well until the united states went to war . when the vietnam war called up all men age 18 and over for the draft , many wondered whether it was fair to send men who could n't vote to war . in 1971 , the 26th amendment to the constitution made all citizens 18 and older eligible to vote , the last major expansion of voting rights in the united states . today , the pool of eligible voters in the u.s. is far broader and more inclusive than ever before in u.s. history . but , of course , it 's not perfect . there are still active efforts to suppress some groups from voting , and only about 60 % of those who can vote do . now that you know all the hard work that went into securing the right to vote , what do you think ? do enough citizens have the right to vote now ? and among those who can vote , why do n't more of them do it ?
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now , any citizen over the age of 21 could vote . all seemed well until the united states went to war . when the vietnam war called up all men age 18 and over for the draft , many wondered whether it was fair to send men who could n't vote to war .
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which of these prohibits a person from voting in the united states today ?
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if you lined up all the blood vessels in your body , they 'd be 95,000 kilometers long and everyday , they carry the equivalent of over 7,500 liters of blood , though that 's actually the same four or five liters recycled over and over , delivering oxygen , and precious nutrients like glucose and amino acids to the body 's tissues . all that blood exerts a force on the muscular walls of the blood vessels . that force is called blood pressure , and it rises and falls with the phases of the heartbeat . it 's highest during systole , when the heart contracts to force blood through the arteries . this is your systolic blood pressure . when the heart is at rest between beats , blood pressure falls to its lowest value , the diastolic pressure . a typical healthy individual produces a systolic pressure between 90 and 120 millimeters of mercury , and diastolic pressure between 60 and 80 . taken together , a normal reading is a bit less than 120 over 80 . the blood traverses the landscape of the body through the pipes of the circulatory system . in any plumbing system , several things can increase the force on the walls of the pipes : the properties of the fluid , extra fluid , or narrower pipes . so if the blood thickens , a higher pressure is needed to push it , so the heart will pump harder . a high-salt diet will lead to a similar result . the salt promotes water retention , and the extra fluid increases the blood volume and blood pressure , and stress , like the fight or flight response , releases hormones , like epinephrine and norepinephrine that constrict key vessels , increasing the resistance to flow and raising the pressure upstream . blood vessels can usually handle these fluctuations easily . elastic fibers embedded in their walls make them resilient , but if your blood pressure regularly rises above about 140 over 90 , what we call hypertension , and stays there , it can cause serious problems . that 's because the extra strain on the arterial wall can produce small tears . when the injured tissue swells up , substances that respond to the inflammation , like white blood cells , collect around the tears . fat and cholesterol floating in the blood latch on , too , eventually building up to form a plaque that stiffens and thickens the inner arterial wall . this condition is called atherosclerosis , and it can have dangerous consequences . if the plaque ruptures , a blood clot forms on top of the tear , clogging the already narrowed pipe . if the clot is big enough , it can completely block the flow of oxygen and nutrients to cells downstream . in vessels that feed the heart , that will cause a heart attack , when oxygen-deprived cardiac muscle cells start to die . if the clot cuts off blood flow to the brain , it causes a stroke . dangerously clogged blood vessels can be widened by a procedure called an angioplasty . there , doctors thread a wire through the vessel to the obstructed site , and then place a deflated balloon catheter over the wire . when the balloon is inflated , it forces the passageway open again . sometimes a rigid tube called a stent is placed in a vessel to held hold it open , letting the blood flow freely to replenish the oxygen-starved cells downstream . staying flexible under pressure is a tough job for arteries . the fluid they pump is composed of substances that can get sticky and clog them , and your typical healthy heart beats about 70 times a minute , and at least 2.5 billion times during an average lifetime . that may sound like an insurmountable amount of pressure , but do n't worry , your arteries are well suited for the challenge .
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it 's highest during systole , when the heart contracts to force blood through the arteries . this is your systolic blood pressure . when the heart is at rest between beats , blood pressure falls to its lowest value , the diastolic pressure . a typical healthy individual produces a systolic pressure between 90 and 120 millimeters of mercury , and diastolic pressure between 60 and 80 .
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during what phase of the cardiac cycle is blood pressure typically lowest ?
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translator : andrea mcdonough reviewer : bedirhan cinar dear subscribers , there are over 250,000 of you now , a critical mass at a critical time . we have the cumulative potential to impact global education . i 've been assembled and given a voice for this video to describe one way to do just that . please allow me 2.5 minutes to explain . my name is ted-ed and i am a symbol for both the ted-ed website and the billions of videos available to you for free on the website known as `` youtube '' . today i invite you on a journey on which you will learn how to use ed.ted.com to create a lesson around the vast majority of videos on the web . when i say , `` create a lesson , '' i mean that you may use the ted-ed website to search for any video on youtube . once you find the perfect video , the one that really blows your hair back , helps you understand , or that makes you pause and say , `` my goodness , the universe is a fascinating place ! `` , you may use ted-ed to enhance that video . you might use the `` let 's begin '' section to set context for interpreting the video or to define a learning objective for your students . or , you might use the `` think '' section to add multiple choice questions with time-coded video hints or open answer questions that beg for thought-provoking , written responses . or , perhaps you 'll use the `` dig deeper '' section to expand upon the video with articles , references , or links to an application , or maybe even your blog . if any feature is not your cup of tea , just click `` exclude '' . and this new feature , `` discuss , '' it lets you create riveting discussions around your favorite bits . learners , you can engage with lessons independently . the site will save your answers , notes , and ideas to your personal profile and track your learning over time . new lessons are added every day . teachers , as you build or distribute customized lessons to individuals or to groups , you may use the site to track the progress of single students or your entire class . and no matter who you are , if you take the time to create a particularly stunning lesson , please also take the time to nominate it . we will systematically feature the best community-made lessons within the ever-growing ted-ed library , free for the world to learn from , to customize and to share . the possibilities of this tool are as infinite as youtube itself . and , we will be adding new features regularly in the months and years to come . to join me and many others in building a library of lessons worth sharing , simply click on one of the features that interests you . thank you for your time .
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please allow me 2.5 minutes to explain . my name is ted-ed and i am a symbol for both the ted-ed website and the billions of videos available to you for free on the website known as `` youtube '' . today i invite you on a journey on which you will learn how to use ed.ted.com to create a lesson around the vast majority of videos on the web .
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what type of videos can you flip using the ted-ed website ?
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we have some good reasons to completely switch over to solar power . it 's cheaper in many cases , and definitely more sustainable than our dependance on traditional power plants that use resources like coal , which will eventually run out . so why do n't we replace these traditional plants with solar energy ? because there 's one factor that makes solar power very unpredictable : cloud cover . as the sun 's rays move towards earth , some get absorbed by the earth 's atmosphere , some are reflected back into outer space , but the rest make it to the earth 's surface . the ones that are n't deviated are called direct irradiance . the ones that are deflected by clouds are called diffuse irradiance . and those rays that first get reflected by a surface , like a nearby building , before reaching the solar energy system are called reflected irradiance . but before we can examine how clouds affect the sun 's rays and electricity production , let 's see how these solar energy systems work . first up , we have solar towers . these are made up of a central tower surrounded by a huge field of mirrors that track the sun 's path and focus only the direct rays onto a single point on the tower , kind of like an eager beachgoer . the heat generated by these rays is so immense that it can be used to boil water producing steam that drives a traditional turbine , which makes electricity . but when we say solar energy systems , we 're usually talking about photovoltaics , or solar panels , which are the systems most commonly used to generate solar power . in solar panels , photons from the sun 's rays hit the surface of a panel , and electrons are released to get an electric current going . solar panels can use all types of irradiance , while solar towers can only use direct irradiance , and this is where clouds become important because depending on their type and location relative to the sun , they can either increase or decrease the amount of electricity produced . for instance , even a few cumulus clouds in front of the sun can reduce the electricity production in solar towers to almost zero because of this dependence on direct rays . in solar panels , those clouds would decrease energy output as well , though not as much because solar panels can use all types of irradiance . however , all this depends on the clouds exact positioning . due to reflection , or a particular phenomeon called mie scattering , the sun 's rays can actually be focused forward by clouds to create a more than 50 % increase in the solar irradiance reaching a solar panel . if this potential increase is n't accounted for , it could damage the solar panel . why does this matter ? well , you would n't want this lesson to stop just because a cloud passed over the panel on your roof . in solar towers , huge tanks of molten salt or oil can be used to store any excess heat and use it when needed , so that 's how they manage the problem of fluctuating solar irradiance to smooth out electricity production . but in the case of solar panels , there currently is n't any way to affordably store extra energy . that 's where traditional power plants come in because to correct for any fluctuations in these solar powered plants , extra electricity from traditional sources always needs to be available . but then why are n't these tradtional power plants just used as a backup , instead of us humans depending on them as our main sources of energy ? because it 's impossible for an employee at a coal fired or a nuclear plant to turn a knob to produce more or less electricity depending on how many clouds there are in the sky . the response time would simply be too slow . instead , to accommodate these fluctuations , some extra electricity from traditional power plants is always being produced . on clear sky days , that extra electricity might be wasted , but when cloudy skies prevail , it 's what fills the gap . this is what we currently depend on for a constant supply of energy . for this reason , a lot of researchers are interested in forcasting the motion and formation of clouds through satellite images or cameras that look up at the sky to maximize the energy from solar power plants and minimize energy waste . if we could accomplish that , you 'd be able to enjoy this video powered solely by the sun 's rays , no matter what the weather , although if the sun is shining , you may be tempted to venture outside to go and do a different kind of cloud gazing .
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for instance , even a few cumulus clouds in front of the sun can reduce the electricity production in solar towers to almost zero because of this dependence on direct rays . in solar panels , those clouds would decrease energy output as well , though not as much because solar panels can use all types of irradiance . however , all this depends on the clouds exact positioning . due to reflection , or a particular phenomeon called mie scattering , the sun 's rays can actually be focused forward by clouds to create a more than 50 % increase in the solar irradiance reaching a solar panel . if this potential increase is n't accounted for , it could damage the solar panel .
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can clouds increase solar irradiance reaching a photovoltaic ?
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acids and bases are everywhere . they 're used to make foods , soaps and detergents , fertilizers , explosives , dyes , plastics , pesticides , even paper . our stomachs are very acidic . our blood is slightly basic . our proteins are made up of amino acids , and the letters in our genetic code , those as , ts , cs , and gs , are all bases . you were probably taught how acids and bases behave on the molecular level . you were probably never taught that a long time ago , like ancient greek ago , before anyone knew about atoms or molecules , acids and bases were defined by how they behaved . acids tasted sour and corroded metal . bases felt slippery and could somehow counteract acids . when molecules dissolved in water interact , they are exchanging two main currencies with their surroundings : protons , also known as hydrogen ions , and electrons . depending on how a molecule is composed or shaped , it may be willing to donate or accept either protons or electrons with some other community member . and some molecules are far more aggressive than others when it comes to donating or accepting either currency . remember that protons are positively charged and electrons are negatively charged . so , if a molecule is willing to give up a proton , that 's not too different from it being willing to accept an electron -- either way it 's becoming more negatively charged . other molecules are willing to accept a proton or give up an electron . these are becoming more positively charged . some substances are so aggressive about donating their protons that when they get a chance , all of the molecules in a sample will dump a proton , sometimes more than one , to the surrounding water molecules . we call these strong acids . meanwhile , some compounds are so ready to accept a proton that they wo n't wait around , they 'll just rip one off water , which usually has two protons but is generous enough to hang out with just one . we call these strong bases . other acids and bases are not so strong . they may donate just a few of their protons to water or accept just a few protons from water , but most of their molecules stay exactly the same . if left alone in water , they 'll reach some equilibrium point where maybe only one out of a hundred or one out of ten thousand of their molecules has exchanged currency with water . as you might guess , we label these acids and bases weak , but in the common sense of the word , they 're not weak . the vinegar in your salad dressing that you can smell from across the room , that is a weak acid . the ammonia you spray on glass for a streak-free shine , that is a weak base . so , it does n't take much to be an active player in the chemical economy . most acid-base chemistry takes place in water , which can act as either an acid or a base , accepting deposits and enabling withdrawals like a 24-hour molecular atm . and when a proton-deposit customer , that 's an acid , and a proton-withdrawal customer , the base , shop at the same time , their net effect on water 's account may cancel out , and we call this neutralization . now , certain molecules can behave as acids or bases without water , but that 's another story . let 's end by saluting water as the resilient and fair banker for acids and bases . it 's always open for business , does n't charge interest , and will never foreclose on your molecules , which is more than i can say for [ bleep ] . waah-waah .
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other molecules are willing to accept a proton or give up an electron . these are becoming more positively charged . some substances are so aggressive about donating their protons that when they get a chance , all of the molecules in a sample will dump a proton , sometimes more than one , to the surrounding water molecules .
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what ’ s the difference between a proton and a positively charged hydrogen ion ?
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sea turtles are miraculous . first , they 've been around since the late jurassic , roughly 150 million years ago . cohorts of the dinosaurs , sea turtles have survived through the challenges of eons , existing still today , where many others have ended their evolutionary run . second , throughout the centuries and up till today , every living adult sea turtle has overcome the odds , existing as a consequence of chance , skill , and capability . the gauntlet each sea turtle faces in the course of its lifetime goes thus : first , deposited as a clutch of leathery , ping-pong ball-sized eggs into a nesting pit dug by its mother high on the beach , of the 50 to 200 eggs laid , roughly 20 percent will never hatch . roughly a month and a half after having been laid , the surviving eggs hatch , and the young turtles , each small enough to fit in the palm of your hand , squirm to the surface , emerging from the sand en masse , and making their desperate dash for the sea . along the way , debris , pitfalls , crabs , gulls , raccoons , and other threats will claim roughly 50 percent of those who rose from the sand . for those that actually reach the surf , they trade one set of threats for another , as they first face the repelling force of the waves , and then find a whole new host of predators awaiting them : various fish , dolphins , sharks , and sea birds , as the young turtles come to the surface for air . for their first few days of life , should they count themselves amongst the living , the vulnerable turtles swim frantically forward . ultimately , they will often look to settle in a patch of flotsam , preferably a patch of floating seaweed . now for the next several months , they will seek to avoid those that would eat them , find that which they might eat themselves , and not fall to the pressures of challenging weather or unfortunate currents . in this phase , roughly 50 percent of those who reach the surf will perish . ultimately , with the passage of years , the survivors will increase in size , from that of a dinner plate at year one to that of a dinner table , in the case of one species at least , the leatherback , a decade or so later . with size comes some measure of protection . the only truly worrisome predators now are some of the larger shark species -- bulls , tigers , and whites -- and the occasional killer whale . at approximately two decades of age , the survivors will be old enough themselves to breed , and continue the cycle which their very existence heralds . of those that began as eggs on a distant beach , now less than 10 percent remain , at least , those were the odds prior to significant human interference . over the past century , and in particular in the last several decades , human endeavors , from beach development to plastic refuse to poaching , long lines , nets , and even noxious chemicals , including oil , have upped the ante for sea turtles , causing their survival rate to drop to around one percent or less , from each nesting cycle . it is this added human pressure which has pushed each of the eight sea turtle species into either a threatened or endangered state . for while they have evolved to overcome a host of obstacles , the most recent has arisen so quickly and at such scale that the species find themselves overwhelmed . so let 's quickly recap this cycle of odds . using a hypothetical nesting season , for females may nest multiple times in a single year , of 1,000 eggs , for sake of ease . 1000 eggs laid . 800 hatch . 400 make it to the water . 200 progress toward adulthood . 20 survive to breeding age -- that is , without human interference . two survive to breeding age with human interference . so a breeding adult sea turtle is the very embodiment of a long shot . it is the exception , not the rule . a jackpot . it is , in a very real sense , a miracle .
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over the past century , and in particular in the last several decades , human endeavors , from beach development to plastic refuse to poaching , long lines , nets , and even noxious chemicals , including oil , have upped the ante for sea turtles , causing their survival rate to drop to around one percent or less , from each nesting cycle . it is this added human pressure which has pushed each of the eight sea turtle species into either a threatened or endangered state . for while they have evolved to overcome a host of obstacles , the most recent has arisen so quickly and at such scale that the species find themselves overwhelmed .
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while not every species faces the same daunting odds of survival experienced by a sea turtle , all life is subject to challenges . particularly when viewed from the perspective of an individual , the likelihood of existence is bewilderingly slight . discuss how such a condition affects the valuation of mature individual species ( yourself included ) .
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each time you take a step , 200 muscles work in unison to lift your foot , propel it forward , and set it down . it 's just one of the many thousands of tasks performed by the muscular system . this network of over 650 muscles covers the body and is the reason we can blink , smile , run , jump , and stand upright . it 's even responsible for the heart 's dependable thump . first , what exactly is the muscular system ? it 's made up of three main muscle types : skeletal muscle , which attaches via tendons to our bones , cardiac muscle , which is only found in the heart , and smooth muscle , which lines the blood vessels and certain organs , like the intestine and uterus . all three types are made up of muscle cells , also known as fibers , bundled tightly together . these bundles receive signals from the nervous system that contract the fibers , which in turn generates force and motion . this produces almost all the movements we make . some of the only parts of the body whose motions are n't governed by the muscular system are sperm cells , the hair-like cilia in our airways , and certain white blood cells . muscle contraction can be split into three main types . the first two , shortening muscle fibers and lengthening them , generate opposing forces . so the biceps will shorten while the triceps will lengthen or relax , pulling up the arm and making it bend at the elbow . this allows us to , say , pick up a book , or if the muscle relationship is reversed , put it down . this complementary partnership exists throughout the muscular system . the third type of contraction creates a stabilizing force . in these cases , the muscle fibers do n't change in length , but instead keep the muscles rigid . this allows us to grip a mug of coffee or lean against a wall . it also maintains our posture by holding us upright . skeletal muscles form the bulk of the muscular system , make up about 30-40 % of the body 's weight , and generate most of its motion . some muscles are familiar to us , like the pectorals and the biceps . others may be less so , like the buccinator , a muscle that attaches your cheek to your teeth , or the body 's tiniest skeletal muscle , a one-millimeter-long tissue fragment called the stapedius that 's nestled deep inside the ear . wherever they occur , skeletal muscles are connected to the somatic nervous system , which gives us almost complete control over their movements . this muscle group also contains two types of muscle fibers to refine our motions even further , slow-twitch and fast-twitch . fast-twitch fibers react instantly when triggered but quickly use up their energy and tire out . slow-twitch fibers , on the other hand , are endurance cells . they react and use energy slowly so they can work for longer periods . a sprinter will accumulate more fast-twitch muscles in her legs through continuous practice , enabling her to quickly , if briefly , pick up the pace , whereas back muscles contain more slow-twitch muscles to maintain your posture all day . unlike the skeletal muscles , the body 's cardiac and smooth muscles are managed by the autonomic nervous system beyond our direct control . that makes your heart thump roughly 3 billion times over the course of your life , which supplies the body with blood and oxygen . autonomic control also contracts and relaxes smooth muscle in a rhythmic cycle . that pumps blood through the smooth internal walls of blood vessels , enables the intestine to constrict and push food through the digestive system , and allows the uterus to contract when a person is giving birth . as muscles work , they also use energy and produce an important byproduct , heat . in fact , muscle provides about 85 % of your warmth , which the heart and blood vessels then spread evenly across the body via the blood . without that , we could n't maintain the temperature necessary for our survival . the muscular system may be largely invisible to us , but it leaves its mark on almost everything we do , whether it 's the blink of an eye or a race to the finish line .
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they react and use energy slowly so they can work for longer periods . a sprinter will accumulate more fast-twitch muscles in her legs through continuous practice , enabling her to quickly , if briefly , pick up the pace , whereas back muscles contain more slow-twitch muscles to maintain your posture all day . unlike the skeletal muscles , the body 's cardiac and smooth muscles are managed by the autonomic nervous system beyond our direct control .
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describe the functional difference between fast and slow twitch muscles .
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so you can see on the front of this instrument is a dome shaped device . that dome is a special vessel which is made so we can control the atmosphere inside and it is fabricated from beryllium metal . this is the beryllium which i don ’ t really want to get out . why not ? well , because it is a toxic chemical , a toxic metal . beryllium is an interesting element because most chemists don ’ t really know about it very much at all . so beryllium is a fantastic metal , it is really , really interesting , it ’ s got really lots of strange metallic properties , but one of the most important to me is that it is transparent to x-rays . so i can shine x-rays straight through the beryllium and the beryllium does not absorb it at all which most other metals especially those with higher molecular weights do . beryllium-laden dust has been shown to cause berylliosis which is actually an industrial lung disease which causes the formation of swollen nodules in the lungs called granulomas which is a bit gross , so i don ’ t really want to open up the jar . it ’ s near the beginning of the periodic table , but we rarely come across it . so at the moment we are at matt ’ s lab and we are doing some x-ray experiments on a really , really quite sensitive compound . so x-rays themselves are absorbed by everything , ok , so when we shoot it through the air it is absorbed by the air , so to measure the x-ray absorption of our compound which is sensitive to the air we need to be able to remove the air and encase it so we use beryllium to make a magic box around our sample , that the x-rays can come into , interact with our sample , and then exit without interacting with the material around them . so you can see on the front of this instrument , there is a dome shaped device , that dome , is a special vessel which is made so that we could control the atmosphere inside and it is fabricated from beryllium metal . i talk about in my lectures , i explain that beryllium chloride the molecule that has three atoms , two chlorine atoms and one beryllium atom , has the three atoms arranged in the row , so it is a straight molecule so called linear molecule . i have never seen beryllium chloride . chemists use it on x-ray defractometers because actually it is so lightweight it is actually got atomic number 4 . the beryllium allows the x-rays to come in and out without interacting at all . it is a fantastic device it is really useful for really sensitive chemistry , it is a really beautiful application . the cost of that beryllium though , that is significant , that small beryllium sample cost 15,000 euros . it only has four protons and a number of neutrons so if x-rays fall on atoms of beryllium they are not scattered very much so it ’ s like the difference between shining light through a glass window and if you made it out of a heavy material it would be like , shining through paper , it would be scattered you wouldn ’ t get a good image . i ’ m hoping to actually do some chemistry with beryllium which is why i ’ ve bought it . it is pretty toxic so we are going to have to be very , very careful . you can ’ t actually breathe in the dust at all , cause even actually one exposure has shown with some people one exposure is enough to cause this sort of sensitive reaction . but beryllium is very poisonous so if you do use these beryllium windows , you have to be careful not to lick your fingers . well good chemists shouldn ’ t lick their fingers anyway .
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so beryllium is a fantastic metal , it is really , really interesting , it ’ s got really lots of strange metallic properties , but one of the most important to me is that it is transparent to x-rays . so i can shine x-rays straight through the beryllium and the beryllium does not absorb it at all which most other metals especially those with higher molecular weights do . beryllium-laden dust has been shown to cause berylliosis which is actually an industrial lung disease which causes the formation of swollen nodules in the lungs called granulomas which is a bit gross , so i don ’ t really want to open up the jar .
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the green and beautiful gemstone , emerald , is a variety of the mineral beryl and is a beryllium aluminium silicate . what is its molecular formula ?
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dear mr. president , do you know much about physics ? i mean , you 're the president of the united states : a country with five thousand nuclear weapons , birthplace of the world 's computing and telecommunications industry , home of the first atomic clock and creator of the global positioning system . but chances are , if you just took regular american high school physics , you do n't know one iota about the science behind these things ( no offense ) . that 's because high school physics students across most of america are not required to learn about pretty much any physical phenomena discovered or explained more recently than 1865 . yes , 1865 . that 's the year the civil war ended and well over a decade before albert einstein was even born ! you know what can happen in 150 years , mr. president ? a lot . velcro , for one . but let me list some useful and important ideas of the last 150 years of physics that are n't a required part of most standard us high school physics courses : photons . the structure of atoms . the existence of antimatter . gps . lasers . transistors . diodes and leds . quarks . chaos theory . electron microscopy . mri scanning . the big bang . black holes . star formation . the fact that gravity bends light . the fact that the universe is expanding . the higgs boson and the weak and strong nuclear forces and all the rest of quantum mechanics and relativity and the topic of every single nobel prize in physics since… always . basically , most of the important stuff . i mean , mr. president , imagine if history classes did n't talk about the abolition of slavery , world wars i or ii , the great depression , the rise of the us as a global superpower , the cold war or the civil rights movement or heaven forbid the first african american president . or imagine if biology classes did n't talk about dna , or hormones , or cell reproduction or the modern germ theory of disease or ecology . or if geologists did n't talk about plate tectonics . and computer scientists… well… in 1865 a computer was a person who computed your taxes . now , if you were lucky enough to have an ambitious teacher or take advanced placement physics , then you might have learned about some of einstein 's discoveries of 1905 ! yes ! current events ! but learning about how einstein 's work helped set the stage for a century of amazing developments in our understanding of the universe is not a part of the standard curriculum . so why , mr. president , am i addressing this letter to you ? well , you appoint the secretary of education , for one - and i do believe that high school physics is somewhat related to education . now , maybe your education secretary says , `` ancient physics is already hard to teach to high schoolers . and you want us to teach them modern physics which is even harder ? ! students ca n't really appreciate the beauty of modern physics without fancy college level mathematics . '' rubbish . ever heard of carl sagan ? richard feynman ? or neil degrasse tyson ? these great men have been 100 % committed to the appreciation and dissemination of the awesomeness of the universe . and we should be too . how else are we supposed to foster and find our future brilliant innovators , inventors , and explorers ? how can we expect to educate our citizens for the next century if we do n't teach about the last ? and that 's not to say that we should ignore math , either - on the contrary , math is one of the most beautiful and awesome things in the universe , especially because it allows us to understand the universe . in particular , the last 150 years have borne fruit to perhaps the most drastic changes in our understanding of the universe , ever , and these new ways of thinking and solving problems should be the centerpiece of an education in physics . between you and me , mr. president , i think we 'd better start making physics education more awesome here in the us , otherwise the next carl sagan or richard feynman will come from somewhere with more educational foresight - maybe even , the internet . sincerely , a collection of atoms known as henry ps you 're probably super busy , but if you 'd like to hear about physics education across the atlantic , i highly recommend heading over to brady 's channel , sixty symbols , for a perspective from the uk . i bet you 'll enjoy it .
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so why , mr. president , am i addressing this letter to you ? well , you appoint the secretary of education , for one - and i do believe that high school physics is somewhat related to education . now , maybe your education secretary says , `` ancient physics is already hard to teach to high schoolers .
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the creator of the video claims that physics education in america currently fails to address any of the developments in physics that were made after what year ?
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in 1895 , a physicist named wilhelm roentgen was doing experiments with a cathode tube , a glass container in which a beam of electrons lights up a fluorescent window . he had wrapped cardboard around the tube to keep the fluorescent light from escaping , when something peculiar happened . another screen outside the tube was glowing . in other words , invisible rays had passed through the cardboard . wilhelm had no idea what those rays were , so he called them x-rays , and his discovery eventually won him a nobel prize . here 's what we now know was happening . when high energy electrons in the cathode tube hit a metal component , they either got slowed down and released extra energy , or kicked off electrons from the atoms they hit , which triggered a reshuffling that again released energy . in both cases , the energy was emitted in the form of x-rays , which is a type of electromagnetic radiation with higher energy than visible light , and lower energy than gamma rays . x-rays are powerful enough to fly through many kinds of matter as if they are semi-transparent , and they 're particularly useful for medical applications because they can make images of organs , like bones , without harming them , although they do have a small chance of causing mutations in reproductive organs , and tissues like the thyroid , which is why lead aprons are often used to block them . when x-rays interact with matter , they collide with electrons . sometimes , the x-ray transfers all of its energy to the matter and gets absorbed . other times , it only transfers some of its energy , and the rest is scattered . the frequency of these outcomes depends on how many electrons the x-rays are likely to hit . collisions are more likely if a material is dense , or if it 's made of elements with higher atomic numbers , which means more electrons . bones are dense and full of calcium , which has a relatively high atomic number , so they absorb x-rays pretty well . soft tissue , on the other hand , is n't as dense , and contains mostly lower atomic number elements , like carbon , hydrogen , and oxygen . so more of the x-rays penetrate tissues like lungs and muscles , darkening the film . these 2-d pictures are only useful up to a point , though . when x-rays travel through the body , they can interact with many atoms along the path . what is recorded on the film reflects the sum of all those interactions . it 's like trying to print 100 pages of a novel on a single sheet of paper . to see what 's really going on , you would have to take x-ray views from many angles around the body and use them to construct an internal image . and that 's something doctors do all the time in a procedure called a ct , computed tomography scan , another nobel prize winning invention . think of ct like this . with just one x-ray , you might be able to see the density change due to a solid tumor in a patient , but you would n't know how deep it is beneath the surface . however , if you take x-rays from multiple angles , you should be able to find the tumor 's position and shape . a ct scanner works by sending a fan or cone of x-rays through a patient to an array of detectors . the x-ray beam is rotated around the patient , and often also moved down the patient 's body , with the x-ray source tracing a spiral trajectory . spiral ct scans produce data that can be processed into cross sections detailed enough to spot anatomical features , tumors , blood clots , and infections . ct scans can even detect heart disease and cavities in mummies buried thousands of years ago . so what began as roentgen 's happy accident has become a medical marvel . hospitals and clinics now conduct over 100 millions scans each year worldwide to treat diseases and save lives .
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however , if you take x-rays from multiple angles , you should be able to find the tumor 's position and shape . a ct scanner works by sending a fan or cone of x-rays through a patient to an array of detectors . the x-ray beam is rotated around the patient , and often also moved down the patient 's body , with the x-ray source tracing a spiral trajectory . spiral ct scans produce data that can be processed into cross sections detailed enough to spot anatomical features , tumors , blood clots , and infections .
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normally the healthcare benefits of medical x-ray ct procedures are far more than a small potential risk to an involved patient . what are some ways in which fewer x-rays can be used to reduce the radiation risk to a patient ?
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homer 's `` odyssey '' , one of the oldest works of western literature , recounts the adventures of the greek hero odysseus during his ten-year journey home from the trojan war . though some parts may be based on real events , the encounters with strange monsters , terrifying giants and powerful magicians are considered to be complete fiction . but might there be more to these myths than meets the eye ? let 's look at one famous episode from the poem . in the midst of their long voyage , odysseus and his crew find themselves on the mysterious island of aeaea . starving and exhausted , some of the men stumble upon a palatial home where a stunning woman welcomes them inside for a sumptuous feast . of course , this all turns out to be too good to be true . the woman , in fact , is the nefarious sorceress circe , and as soon as the soldiers have eaten their fill at her table , she turns them all into animals with a wave of her wand . fortunately , one of the men escapes , finds odysseus and tells him of the crew 's plight . but as odysseus rushes to save his men , he meets the messenger god , hermes , who advises him to first consume a magical herb . odysseus follows this advice , and when he finally encounters circe , her spells have no effect on him , allowing him to defeat her and rescue his crew . naturally , this story of witchcraft and animal transformations was dismissed as nothing more than imagination for centuries . but in recent years , the many mentions of herbs and drugs throughout the passage have piqued the interest of scientists , leading some to suggest the myths might have been fictional expressions of real experiences . the earliest versions of homer 's text say that circe mixed baneful drugs into the food such that the crew might utterly forget their native land . as it happens , one of the plants growing in the mediterranean region is an innocent sounding herb known as jimson weed , whose effects include pronounced amnesia . the plant is also loaded with compounds that disrupt the vital neurotransmitter called acetylcholine . such disruption can cause vivid hallucinations , bizarre behaviors , and general difficulty distinguishing fantasy from reality , just the sorts of things which might make people believe they 've been turned into animals , which also suggests that circe was no sorceress , but in fact a chemist who knew how to use local plants to great effect . but jimson weed is only half the story . unlike a lot of material in the odyssey , the text about the herb that hermes gives to odysseus is unusually specific . called moly by the gods , it 's described as being found in a forest glen , black at the root and with a flower as white as milk . like the rest of the circe episode , moly was dismissed as fictional invention for centuries . but in 1951 , russian pharmacologist mikhail mashkovsky discovered that villagers in the ural mountains used a plant with a milk-white flower and a black root to stave off paralysis in children suffering from polio . the plant , called snowdrop , turned out to contain a compound called galantamine that prevented the disruption of the neurotransmitter acetylcholine , making it effective in treating not only polio but other disease , such as alzheimer 's . at the 12th world congress of neurology , doctors andreas plaitakis and roger duvoisin first proposed that snowdrop was , in fact , the plant hermes gave to odysseus . although there is not much direct evidence that people in homer 's day would have known about its anti-hallucinatory effects , we do have a passage from 4th century greek writer theophrastus stating that moly is used as an antidote against poisons . so , does this all mean that odysseus , circe , and other characters in the odyssey were real ? not necessarily . but it does suggest that ancient stories may have more elements of truth to them than we previously thought . and as we learn more about the world around us , we may uncover some of the same knowledge hidden within the myths and legends of ages passed .
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the earliest versions of homer 's text say that circe mixed baneful drugs into the food such that the crew might utterly forget their native land . as it happens , one of the plants growing in the mediterranean region is an innocent sounding herb known as jimson weed , whose effects include pronounced amnesia . the plant is also loaded with compounds that disrupt the vital neurotransmitter called acetylcholine . such disruption can cause vivid hallucinations , bizarre behaviors , and general difficulty distinguishing fantasy from reality , just the sorts of things which might make people believe they 've been turned into animals , which also suggests that circe was no sorceress , but in fact a chemist who knew how to use local plants to great effect .
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what happens when acetylcholine is disrupted ?
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myths and misconceptions about evolution . let 's talk about evolution . you 've probably heard that some people consider it controversial , even though most scientists do n't . but even if you are n't one of those people and you think you have a pretty good understanding of evolution , chances are you still believe some things about it that are n't entirely right , things like , `` evolution is organisms adapting to their environment . '' this was an earlier , now discredited , theory of evolution . almost 60 years before darwin published his book , jean-baptiste lamarck proposed that creatures evolve by developing certain traits over their lifetimes and then passing those on to their offspring . for example , he thought that because giraffes spent their lives stretching to reach leaves on higher branches , their children would be born with longer necks . but we know now that 's not how genetic inheritance works . in fact , individual organisms do n't evolve at all . instead , random genetic mutations cause some giraffes to be born with longer necks , and that gives them a better chance to survive than the ones who were n't so lucky , which brings us to `` survival of the fittest '' . this makes it sound like evolution always favors the biggest , strongest , or fastest creatures , which is not really the case . for one thing , evolutionary fitness is just a matter of how well-suited they are to their current environment . if all the tall trees suddenly died out and only short grass was left , all those long-necked giraffes would be at a disadvantage . secondly , survival is not how evolution occurs , reproduction is . and the world if full of creatures like the male anglerfish , which is so small and ill-suited for survival at birth that it has to quickly find a mate before it dies . but at least we can say that if an organism dies without reproducing , it 's evolutionarily useless , right ? wrong ! remember , natural selection happens not at the organism level , but at the genetic level , and the same gene that exists in one organism will also exist in its relatives . so , a gene that makes an animal altruistically sacrifice itself to help the survival and future reproduction of its siblings or cousins , can become more widespread than one that is solely concerned with self-preservation . anything that lets more copies of the gene pass on to the next generation will serve its purpose , except evolutionary purpose . one of the most difficult things to keep in mind about evolution is that when we say things like , `` genes want to make more copies of themselves , '' or even , `` natural selection , '' we 're actually using metaphors . a gene does n't want anything , and there 's no outside mechanism that selects which genes are best to preserve . all that happens is that random genetic mutations cause the organisms carrying them to behave or develop in different ways . some of those ways result in more copies of the mutated gene being passed on , and so forth . nor is there any predetermined plan progressing towards an ideal form . it 's not ideal for the human eye to have a blind spot where the optic nerve exits the retina , but that 's how it developed , starting from a simple photoreceptor cell . in retrospect , it would have been much more advantageous for humans to crave nutrients and vitamins rather than just calories . but over the millenia , during which our ancestors evolved , calories were scarce , and there was nothing to anticipate that this would later change so quickly . so , evolution proceeds blindly , step by step by step , creating all of the diversity we see in the natural world .
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but we know now that 's not how genetic inheritance works . in fact , individual organisms do n't evolve at all . instead , random genetic mutations cause some giraffes to be born with longer necks , and that gives them a better chance to survive than the ones who were n't so lucky , which brings us to `` survival of the fittest '' .
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why do some non- ‘ ideal ’ traits exist in organisms ?
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translator : andrea mcdonough reviewer : bedirhan cinar at birth , our bodies are roughly 75 % water . we remain mostly water for the rest of our lives . we can not survive even a week without fresh water . there 's no life without it for ecosystems , societies , and individuals . so , how much usable water is there on earth ? most of the water on earth is ocean , a salty 97.5 % , to be precise , and the remaining 2.5 % is fresh water . that little sliver of liquid sustains human life on earth , it literally holds up civilizations . 2.5 % is a small proportion to be sure , and even that is broken down into smaller parts : surface water , water in ice caps and polar regions , and ground water . first , surface water . all the liquid water above ground is surface water and it is a tiny blip of an amount . 0.3 % of all fresh water is surface water . it may seem counterintuitive , but it accounts for little streams all over the planet . all rivers , including the nile , the jordan , and the mississippi , and lakes , large to small , like victoria , the great lakes , and baikal . second , ice caps and polar regions freeze up to 70 % of the planet 's fresh water . this water is significant , but it is n't available for human use in a regular way . finally , nearly 30 % of all water on earth is ground water . as the name suggests , that 's water in the ground . it can rest still and deep in huge caverns , or it can snuggle in the little crevices of rock and pebble . the upshot - thank goodness for ground water ! it 's invisible to us , but it is much more plentiful than surface water . it is much more reliable and easier to obtain than frozen water . without ground water , our societies would be parched . so , how are we using that water ? as a result of industrialization and population growth , demand for fresh water skyrocketed in the last century . where is all that water going ? first , we have to remember that fresh water is a global concern , but it is always local . context matters . the sahara is not seattle . still , some general information can help us get a handle on major trends . who consumes the most fresh water ? and , what sectors consume the most fresh water ? first , who . well , the united states consumes the most water per capita of any country in the entire world , followed by parts of europe and large industrializing nations like china . but , this does n't tell us what water is being used for . so let 's look at it another way . if we ask what kinds of uses water is going towards , we see a different picture . agriculture accounts for roughly 70 % of global fresh water consumption . again , remember the numbers vary by region , but still , it 's a staggering amount . and , this makes a certain kind of sense : we need to eat , we need water to grow food ; the bigger the population , the more food we need ; and , the wealthier we get , the more meat we eat , and the more water is required to produce our food . furthermore , 22 % of all fresh water worldwide goes to industrial uses . this includes the production of electricity , the extraction of fossil fuels , and the manufacturing of all manner of goods , from microchips , to paper , to blimps . 70 % to agriculture , 22 % to industrial uses , what 's left ? 8 % all those domestic uses - cooking , cleaning , bathing , drinking - it 's a drop in the bucket of overall water use .
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all the liquid water above ground is surface water and it is a tiny blip of an amount . 0.3 % of all fresh water is surface water . it may seem counterintuitive , but it accounts for little streams all over the planet .
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what percentage of water on earth is fresh ?
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light : it 's the fastest thing in the universe , but we can still measure its speed if we slow down the animation , we can analyze light 's motion using a space-time diagram , which takes a flipbook of animation panels , and turns them on their side . in this lesson , we 'll add the single experimental fact that whenever anyone measures just how fast light moves , they get the same answer : 299,792,458 meters every second , which means that when we draw light on our space-time diagram , it 's world line always has to appear at the same angle . but we saw previously that speed , or equivalently world line angles , change when we look at things from other people 's perspective . to explore this contradiction , let 's see what happens if i start moving while i stand still and shine the laser at tom . first , we 'll need to construct the space-time diagram . yes , that means taking all of the different panels showing the different moments in time and stacking them up . from the side , we see the world line of the laser light at its correct fixed angle , just as before . so far , so good . but that space-time diagram represents andrew 's perspective . what does it look like to me ? in the last lesson , we showed how to get tom 's perspective moving all the panels along a bit until his world line is completely vertical . but look carefully at the light world line . the rearrangement of the panels means it 's now tilted over too far . i 'd measure light traveling faster than andrew would . but every experiment we 've ever done , and we 've tried very hard , says that everyone measures light to have a fixed speed . so let 's start again . in the 1900s , a clever chap named albert einstein worked out how to see things properly , from tom 's point of view , while still getting the speed of light right . first , we need to glue together the separate panels into one solid block . this gives us our space-time , turning space and time into one smooth , continuous material . and now , here is the trick . what you do is stretch your block of space-time along the light world line , then squash it by the same amount , but at right angles to the light world line , and abracadabra ! tom 's world line has gone vertical , so this does represent the world from his point of view , but most importantly , the light world line has never changed its angle , and so light will be measured by tom going at the correct speed . this superb trick is known as a lorentz transformation . yeah , more than a trick . slice up the space-time into new panels and you have the physically correct animation . i 'm stationary in the car , everything else is coming past me and the speed of light works out to be that same fixed value that we know everyone measures . on the other hand , something strange has happened . the fence posts are n't spaced a meter apart anymore , and my mom will be worried that i look a bit thin . but that 's not fair . why do n't i get to look thin ? i thought physics was supposed to be the same for everyone . yes , no , it is , and you do . all that stretching and squashing of space-time has just muddled together what we used to think of separately as space and time . this particular squashing effect is known as lorentz contraction . okay , but i still do n't look thin . no , yes , you do . now that we know better about space-time , we should redraw what the scene looked like to me . to you , i appear lorentz contracted . oh but to you , i appear lorentz contracted . yes . uh , well , at least it 's fair . and speaking of fairness , just as space gets muddled with time , time also gets muddled with space , in an effect known as time dilation . no , at everyday speeds , such as tom 's car reaches , actually all the effects are much , much smaller than we 've illustrated them . oh , yet , careful experiments , for instance watching the behavior of tiny particles whizzing around the large hadron collider confirmed that the effects are real . and now that space-time is an experimentally confirmed part of reality , we can get a bit more ambitious . what if we were to start playing with the material of space-time itself ? we 'll find out all about that in the next animation .
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light : it 's the fastest thing in the universe , but we can still measure its speed if we slow down the animation , we can analyze light 's motion using a space-time diagram , which takes a flipbook of animation panels , and turns them on their side . in this lesson , we 'll add the single experimental fact that whenever anyone measures just how fast light moves , they get the same answer : 299,792,458 meters every second , which means that when we draw light on our space-time diagram , it 's world line always has to appear at the same angle . but we saw previously that speed , or equivalently world line angles , change when we look at things from other people 's perspective .
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we have chosen to draw the angle of light worldlines at 45 degrees . given the speed of light is 299,792,458 metres per second , what duration does a space-time diagram 20cm wide and 20cm tall represent ? scientists often like to set the speed of light , c , to 1 in what are called `` natural units . '' what do you think this means ? do the units matter ? why do you think the angle of 45 degrees is important ? ( hint - think about the stretch-and-squash trick . )
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translator : andrea mcdonough reviewer : bedirhan cinar normally astronaut training takes about one full year , and it includes such subjects as astronomy , astrophysics , flight physiology , orbital trajectories , or orbital management . another part of the astronaut basic training is survival training . in the days of gemini , you never knew for sure where a spacecraft might land if there was an emergency , deorbit . so , we had to take desert training , water training , and jungle survival training . so , we had to learn how to cook and eat snake and all other , such other good things as that , and how to make water in a desert . after that year and a half of astronaut basic training , our names were all put on a list and that list was quite a bit longer at that time then there were seats available . and so , we were all given other duties to keep us occupied and to help continue our training . five of us were assigned to the lunar module , and our job was to be with these lunar modules as they were being built . so , we spent a lot of time there . i must admit that probably i had more time sleeping on the floor of lunar module # 6 than the crew who flew it on the moon . well , my next job was to be on the support crew of apollo 8 , and apollo 8 was the spacecraft that flew to the moon and came back but did not land . when they went behind the moon , they were supposed to do a thrusting maneuver to slow them down so they would be captured into lunar orbit . so we just had to sit and cool our heels when they went behind the moon , and we knew if they came out a little early on the other side , that they had not burned enough , not slowed down enough , and were going to skip out into space , they would n't be captured in orbit . if they came out a little bit late , it meant they had over-done it , and they were n't going to be in orbit , but were going to begin a spiral down to the lunar surface . and , of course , without a lunar module , that kind of ruins your whole day . you can imagine how relieved we were at the instant that they were supposed to appear on the other side of the moon that they appeared ! my next assignment was again a support crew assignment on apollo 12 , and apollo 12 was struck by lightning on its way off the pad . a nearby thunderstorm , there was a lightning bolt that went over and hit the very tip of the spacecraft . the charge went down through the spacecraft , through the booster , down the exhaust gases , and grounded out on the launching pad . it killed the electrical power system and the computers all died . you can imagine what it must have been like for them inside because suddenly the lights all went out and then they came back on when the batteries picked up the load . and , every single warning light and caution light in the spacecraft was on and flashing , and all the necessary bells , whistles , and buzzards and things that are in there , all were going off at the same time . the crew was totally confused as to what was going on . when we were settled in orbit , we tested all the various systems and everything looked good . so , that , now i figured this is it , and sure enough , i did get an assignment , a flight assignment . i was assigned to the back-up crew of apollo 16 , which meant that i was to be on the param crew of apollo 19 . and , several weeks into the training , nasa made the surprise announcment that they were going to cancel apollos 18 , 19 , and 20 . we were in the middle of the vietnam war , the budget was in bad shape , so you can imagine there were three very , very sad hangdog guys moping around the office because we lost our flight to the moon . but , several weeks later , i got a call from tom stafford , the senior astronaut at that time , and he wanted me in his office , and i went in , and he told me that he was sorry that i had missed my opportunity for the moon , but he said , `` i 've got another assignment for you . '' he said , `` i want you to be the commander of the third and final skylab mission . '' and , he said , `` do you think you could do the job ? '' and i said , `` of course , yes ! '' and , i 'll have to admit , a certain lump in my chest and in my stomach , because i was a rookie , and they normally do n't assign a rookie to be a commander , usually you have to have at least one flight under your belt , but they assigned me to that , which was really kind of a shock because the last rookie commander was neil armstrong on gemini 8 .
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you can imagine how relieved we were at the instant that they were supposed to appear on the other side of the moon that they appeared ! my next assignment was again a support crew assignment on apollo 12 , and apollo 12 was struck by lightning on its way off the pad . a nearby thunderstorm , there was a lightning bolt that went over and hit the very tip of the spacecraft .
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what happened to apollo 12 on its way off the launching pad ?
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( music ) i want everyone to put their hands on top of their head . yeah , yeah , yeah . put your hands on top of your head . just relax . just stay calm . everything will be nice and smooth if you just participate and just relax , okay ? yeah . all right , now put your hands down . do n't be no hero . put your hands down . okay ? all right . now . cool . good . i want you to run all that financial aid . yeah , sucka , put the scholarships in the bag , yeah , yeah . put the scholarships in the bag . yeah , you too , yeah , yeah , yeah . yeah , you . yeah , yeah . you over there , go put the pell grants in the bag . put the pell grants in there too . yeah , you . go . yeah , yeah , yeah . you , go over to that booth and get me some of them subsidized , some of them subsidized loans . it ai n't a game no more . i know you 're hiding the money somewhere here . with all this tuition you got me and my homies payin ' -- woo ! -- i 'm about to get gangster-scholar up in here . up in here . i 'm about to go n.w.a . meets beastie boys if i do n't see the cash , man . cause we 're not gon na take it . ♪ oh ... oh , you thought i was playing . oh , you thought this was a game . back up , back up . mind your business , that 's all . what do you , think this is a game ? what ? huh ? you do n't even know me . i 'll say something else . do n't call me crazy . do not call me -- rives , tell 'em do n't call me crazy before i go crazy . i 'm telling you , now i 'm about to go crazy . i 'm about to go tupac thug life in here . like , `` i ai n't a killer but do n't push me . revenge is like the sweetest joy -- '' woo ! i 'm about to go biggie smalls brooklyn type , like , `` super nintendo , sega genesis . when i was dead broke -- '' woo ! i 'm about to go krs-one cuckoo for cocoa puffs-type wild . like , `` wa da da dang , wa da da da dang , listen to my nine millimeter go bang . '' you know what ? you are dumb . you are really dumb . hide your kids , hide your wife , 'cause we gettin ' financial aid all up and in and around here . you think this is a game ? you think i want to be out here doing this ? do you know how hard it was to find these guns ? all right , i 'm sorry . you understand ? i 'm just trying to get my education . you know what i mean ? i 'm just trying to fight for the opportunity that my great-great-great-grandfather died for , you know what i 'm saying ? you know how my ancestors did sit-ins , just so i can sit in a classroom . and all these years , all y'all been doing is strangling the life out of my bank statement , leaving my pockets as vacant as parking lots . professor willie lynch taught you well , huh ? keep the body , take the money . force feed my people deception and failure . condition our brains to malfunction at the sight of success . just keep the cycle going . make us pay for an education that will end up failing us . put us in debt so we 're giving back the money we earned from our back-breaking work . this seems all too familiar . sounds like the rust of shackles locking their way onto my degree . sounds like the thirteenth amendment in reverse . lecture halls should n't feel like cotton fields , should n't sound like muffled freedom songs trapped in the jaws of a generation 's dreams . oho ! oh , it all makes sense . give us enough to get by but not enough to provide for ourselves . keep us psychologically feeble so we lose our purpose in the process . stop thieving our aspirations out of our sleep . do n't call it financial aid if you 're not helping anyone with it . we have fought . we have fought way too hard to let green paper build a barricade in front of our futures . i will not let you potentially rob food out of my children 's stomach . best believe i 'm going out blasting . i ai n't no killer , but do n't push me . i wish it did n't come to this , but i have to for my cousins in haiti who do n't even know what a college looks like , for my best friend raymond sitting in cell block nine instead of a university , for the nooses hanging my gpa by its neck . there is no other option . there is no other way . just , please , put the money in the bag . put the money in the bag . i just want to go to school , man . i just want to get my education . i just want to learn . i just want to grow . put the money in the bag , please . just put the money in the bag .
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hide your kids , hide your wife , 'cause we gettin ' financial aid all up and in and around here . you think this is a game ? you think i want to be out here doing this ?
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lissaint includes an array of allusions to popular culture . why do you think writers and speakers do this ? are there any potential drawbacks to doing so ?
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translator : andrea mcdonough reviewer : bedirhan cinar i am going to start with a challenge . i want you to imagine each of these two scenes in as much detail as you can . scene number one : `` they gave us a hearty welcome . '' well , who are the people who are giving a hearty welcome ? what are they wearing ? what are they drinking ? ok , scene two : `` they gave us a cordial reception . '' how are these people standing ? what expressions are on their faces ? what are they wearing and drinking ? fix these pictures in your mind 's eye and then jot down a sentence or two to describe them . we 'll come back to them later . now on to our story . in the year 400 c.e . the celts in britain were ruled by romans . this had one benefit for the celts : the romans protected them from the barbarian saxon tribes of northern europe . but then the roman empire began to crumble , and the romans withdrew from britain . with the romans gone , the germanic tribes , the angles , saxons , jutes , and frisians quickly sailed across the water , did away with the celts , and formed kingdoms in the british isles . for several centuries , these tribes lived in britain , and their germanic language , anglo saxon , became the common language , what we call old english . although modern english speakers may think old english sounds like a different language , if you look and listen closely , you 'll find many words that are recognizable . for example , here is what the lord 's prayer looks like in old english . at first glance , it may look unfamiliar , but update the spelling a bit , and you 'll see many common english words . so the centuries passed with britains happily speaking old english , but in the 700 's , a series of viking invasions began , which continued until a treaty split the island in half . on one side were the saxons . on the other side were the danes who spoke a language called old norse . as saxons fell in love with their cute danish neighbors and marriages blurred the boundaries , old norse mixed with old english , and many old norse words like freckle , leg , root , skin , and want are still a part of our language . 300 years later , in 1066 , the norman conquest brought war again to the british isles . the normans were vikings who settled in france . they had abandoned the viking language and culture in favor of a french lifestyle , but they still fought like vikings . they placed a norman king on the english throne and for three centuries , french was the language of the british royalty . society in britain came to have two levels : french-speaking aristocracy and old english-speaking peasants . the french also brought many roman catholic clergymen with them who added latin words to the mix . old english adapted and grew as thousands of words flowed in , many having to do with government , law , and aristocracy . words like council , marriage , sovereign , govern , damage , and parliament . as the language expanded , english speakers quickly realized what to do if they wanted to sound sophisticated : they would use words that had come from french or latin . anglo saxon words seemed so plain like the anglo saxon peasants who spoke them . let 's go back to the two sentences you thought about earlier . when you pictured the hearty welcome , did you see an earthy scene with relatives hugging and talking loudly ? were they drinking beer ? were they wearing lumberjack shirts and jeans ? and what about the cordial reception ? i bet you pictured a far more classy and refined crowd . blazers and skirts , wine and caviar . why is this ? how is it that phrases that are considered just about synonymous by the dictionary can evoke such different pictures and feelings ? `` hearty '' and `` welcome '' are both saxon words . `` cordial '' and `` reception '' come from french . the connotation of nobility and authority has persisted around words of french origin . and the connotation of peasantry , real people , salt of the earth , has persisted around saxon words . even if you never heard this history before , the memory of it persists in the feelings evoked by the words you speak . on some level , it 's a story you already knew because whether we realize it consciously or only subconsciously , our history lives in the words we speak and hear .
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with the romans gone , the germanic tribes , the angles , saxons , jutes , and frisians quickly sailed across the water , did away with the celts , and formed kingdoms in the british isles . for several centuries , these tribes lived in britain , and their germanic language , anglo saxon , became the common language , what we call old english . although modern english speakers may think old english sounds like a different language , if you look and listen closely , you 'll find many words that are recognizable .
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what is so noteworthy about the history of the english language ?
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[ pbs intro ] this episode is supported by 23 and me a long time ago a guy built a tomb out of rocks so he could live in it after he died and not be dead . his son was like “ hey that ’ s cool ” so he built one too.. then his son was like “ me too ” so he made a third and they were all buried there . and that ’ s how we got this . the pyramids of giza . how did people who hadn ’ t even invented the wheel build these things , and… why ? they ’ re so big ! they ’ re so precise ! they ’ re so directionally oriented ! they ’ re so mysterrrrrrious . at first glance they really do look out-of-this world . thing is , the pyramids are much older than you probably think . they were already ancient history to people in ancient history , which led to some pretty wild theories about how they came to be . but pyramid technology didn ’ t just show up out of nowhere . it was the end product of centuries of scientific and cultural evolution , of people… figuring it out . and it definitely wasn ’ t aliens . [ open ] early on , egyptians buried their dead like we do . the desert naturally mummified some corpses , which influenced their religious beliefs : you need to preserve the body to reach the afterlife , and when you get there you ’ ll need all your stuff . rich people ’ s graves had nicer stuff , and they needed to protect their afterlife investment . first with simple mounds , and later with mud brick “ eternal houses ” . then a king named djoser was like “ why have one little mud mastaba when i can have six stone mastabas in a stack ? ” so he stacked six stone mastabas like a mastaba boss and the age of the pyramids had begun . this was literally the first time humans had piled stone this high . egyptians knew totally vertical walls got less stable as they got taller , so djoser ’ s architect stacked bricks at an incline and let gravity do the work . step pyramid achieved ! why pyramids and not other shapes ? if you want to make a big pile of blocks , a pyramid gets you the most stability for the least material . a third of the way up , you ’ ve already laid two-thirds of your stone . halfway , you ’ ve placed more than 80 % . next comes sneferu , mr. pyramid . he built his own step pyramid , but then decided he wanted a smooth one instead , so they started on a second . no one had ever built one of those before , so they made some mistakes . for starters , they built it on sand , which is soft , they laid blocks carelessly , and it was too steep , so halfway through they changed the slope and ended up with this . sneferu was like “ you ’ re not burying me in that ” , so he ordered a third pyramid ! only this time they built a solid foundation , laid the stones in horizontal rows , and precision cut the edges . sneferu ’ s motto ? if at first you don ’ t succeed , try again , and then try again one more time . sneferu had experimented his way to a blueprint for building awesome pyramids the great pyramid at giza , built by his son khufu , took that blueprint to the next level . khufu ’ s pyramid remained the tallest structure on earth for almost 4000 years , until some church tower in the year 1311 , which fell down , so it was tallest again until this radio antenna was finished in 1889 . khufu ’ s son khafre built his pyramid right next to dad ’ s , and he didn ’ t stop innovating . instead of leveling the entire 46,000 square meter footprint , he built his pyramid over a natural stone mound and only leveled the outer edge , which was less work , duh ! it ’ s 3 meters shorter than his dad ’ s , but this higher ground creates the illusion that khafre ’ s pyramid is taller . kids , amirite ? but even these seemingly perfect pyramids weren ’ t without mistakes . khafre ’ s had a slight twist near the top in order to make the edges line up evenly . what ’ s remarkable is egypt ’ s biggest stone pyramids were the product of just three human generations , but those were generations full of trial and error . pyramid building continued for nearly 700 years , and like any product , efficiency started to win out over quality . precision-cut cores were replaced by rough-cut blocks . kings still wrapped their pyramids in fine white limestone , but over the next thousand years that was removed by stone stealers and rock robbers , leaving the cheaply-produced cores to collapse into rubble , which is probably why you ’ ve never heard of them . ironically , the kings were probably disappointed by the whole afterlife thing , but the pyramids themselves have proven to be surprisingly resilient . ancient is not a synonym for stupid . the world ’ s first skyscrapers were tombs , and just like our own buildings , they didn ’ t spring up out of nowhere , they were the product of centuries of engineering trial and error . go back 500 years and show someone a smartphone and they ’ d probably think you were a wizard . but when we look back from the present at the ideas and failures along the way , we see that it ’ s not magic at all ! it ’ s science . and if you still think aliens did it , you ’ re in de-nile . you know , the river . stay curious .
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and that ’ s how we got this . the pyramids of giza . how did people who hadn ’ t even invented the wheel build these things , and… why ?
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pyramids were ideal for building large-scale monuments because the design offered the most stability for the least amount of ...
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translator : andrea mcdonough reviewer : bedirhan cinar once upon a time in the magical and very round land of pi , there lived six swashbuckling musketeers . there names were parentheses , exponents , multiplication , division , addition , and subtraction . but each was known best by his or her mark : the two hands ready to catch a fly of parentheses , the small and raised digits of exponents , the mighty x of multiplication , slash of division , plus of addition , and , well , you can guess the symbol by which little subtraction was best known . the land of pi was not necessarily the most peaceful place , and that 's why the numbers of the kingdom needed the musketeers . the land of pi had been ruled by the numbers as anarcho-syndicalist commune , each number with a vote , but , one powerful number from what we 'll call the imperial senate , engineered a war between some robot things and the knights of the kingdom , and then installed himself as supreme emperor , and then puff the magic digit dragon ate him , and a princess or two , and , well , all the other numbers in the land of pi actually . it was kind of a big day . anyway , the musketeers were called to action to save the land of pi from the voracious dragon . they rode towards him on their valiant steeds and attacked . first multiplication , then parentheses , but that did n't work . the dragon continued eating people . so addition tried , but was thrown aside . exponents leaped at the beast and was quickly squashed . nothing was working . the musketeers huddled and formulated a plan . they would attack in sequence , but who should go first ? they bickered for a while , the dragon ate a few more princesses , and then they finally agreed . they jumped into the first , smallest parentheses inside the great puff the digit dragon . parentheses pointed out where to work first and protected exponents , multiplication , division , addition , and subtraction while they diced and sliced . first here , then , move over there , then there . look out ! there 's another set ! parentheses pointed and exponents took the lead . then , it was multiplication , division , addition , and subtraction , each in turn , always the same order . p-e-m-d-a-s when they finished that set , they went to another , and another , always working inside the parentheses in pemdas order . pop ! pop ! pop ! pop ! pop ! pemdas , there is another spot ! do n't forget , there can be parentheses inside parentheses . there 's one ! and that tricky exponent . there we go ! finally , the pemdas musketeers had whittled puff down to his last fearsome roar . but , having vanquished puff the magic digit dragon , all the empire 's numbers sprang again from this tiny little number one , and they all lived happily ever after . except for the emperor number , which they threw into the mouth of an ancient nesting creature in the desert . the end .
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pop ! pemdas , there is another spot ! do n't forget , there can be parentheses inside parentheses .
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which is not a part of pemdas ?
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a famous ancient greek once said , `` give me a place to stand , and i shall move the earth . '' but this was n't some wizard claiming to perform impossible feats . it was the mathematician archimedes describing the fundamental principle behind the lever . the idea of a person moving such a huge mass on their own might sound like magic , but chances are you 've seen it in your everyday life . one of the best examples is something you might recognize from a childhood playground : a teeter-totter , or seesaw . let 's say you and a friend decide to hop on . if you both weigh about the same , you can totter back and forth pretty easily . but what happens if your friend weighs more ? suddenly , you 're stuck up in the air . fortunately , you probably know what to do . just move back on the seesaw , and down you go . this may seem simple and intuitive , but what you 're actually doing is using a lever to lift a weight that would otherwise be too heavy . this lever is one type of what we call simple machines , basic devices that reduce the amount of energy required for a task by cleverly applying the basic laws of physics . let 's take a look at how it works . every lever consists of three main components : the effort arm , the resistance arm , and the fulcrum . in this case , your weight is the effort force , while your friend 's weight provides the resistance force . what archimedes learned was that there is an important relationship between the magnitudes of these forces and their distances from the fulcrum . the lever is balanced when the product of the effort force and the length of the effort arm equals the product of the resistance force and the length of the resistance arm . this relies on one of the basic laws of physics , which states that work measured in joules is equal to force applied over a distance . a lever ca n't reduce the amount of work needed to lift something , but it does give you a trade-off . increase the distance and you can apply less force . rather than trying to lift an object directly , the lever makes the job easier by dispersing its weight across the entire length of the effort and resistance arms . so if your friend weighs twice as much as you , you 'd need to sit twice as far from the center as him in order to lift him . by the same token , his little sister , whose weight is only a quarter of yours , could lift you by sitting four times as far as you . seesaws may be fun , but the implications and possible uses of levers get much more impressive than that . with a big enough lever , you can lift some pretty heavy things . a person weighing 150 pounds , or 68 kilograms , could use a lever just 3.7 meters long to balance a smart car , or a ten meter lever to lift a 2.5 ton stone block , like the ones used to build the pyramids . if you wanted to lift the eiffel tower , your lever would have to be a bit longer , about 40.6 kilometers . and what about archimedes ' famous boast ? sure , it 's hypothetically possible . the earth weighs 6 x 10^24 kilograms , and the moon that 's about 384,400 kilometers away would make a great fulcrum . so all you 'd need to lift the earth is a lever with a length of about a quadrillion light years , 1.5 billion times the distance to the andromeda galaxy . and of course a place to stand so you can use it . so for such a simple machine , the lever is capable of some pretty amazing things . and the basic elements of levers and other simple machines are found all around us in the various instruments and tools that we , and even some other animals , use to increase our chances of survival , or just make our lives easier . after all , it 's the mathematical principles behind these devices that make the world go round .
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the idea of a person moving such a huge mass on their own might sound like magic , but chances are you 've seen it in your everyday life . one of the best examples is something you might recognize from a childhood playground : a teeter-totter , or seesaw . let 's say you and a friend decide to hop on .
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rewrite the equation that models a balanced teeter-totter to demonstrate equal ratios of the length of the arms and the weights . explain the steps you took .
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there 's a quote usually attributed to the writer mark twain that goes , `` a lie can travel halfway around the world while the truth is putting on its shoes . '' funny thing about that . there 's reason to doubt that mark twain ever said this at all , thus , ironically , proving the point . and today , the quote , whoever said it , is truer than ever before . in previous decades , most media with global reach consisted of several major newspapers and networks which had the resources to gather information directly . outlets like reuters and the associated press that aggregate or rereport stories were relatively rare compared to today . the speed with which information spreads now has created the ideal conditions for a phenomenon known as circular reporting . this is when publication a publishes misinformation , publication b reprints it , and publication a then cites b as the source for the information . it 's also considered a form of circular reporting when multiple publications report on the same initial piece of false information , which then appears to another author as having been verified by multiple sources . for instance , the 1998 publication of a single pseudoscientific paper arguing that routine vaccination of children causes autism inspired an entire antivaccination movement , despite the fact that the original paper has repeatedly been discredited by the scientific community . deliberately unvaccinated children are now contracting contagious diseases that had been virtually eradicated in the united states , with some infections proving fatal . in a slightly less dire example , satirical articles that are formatted to resemble real ones can also be picked up by outlets not in on the joke . for example , a joke article in the reputable british medical journal entitled `` energy expenditure in adolescents playing new generation computer games , '' has been referenced in serious science publications over 400 times . user-generated content , such as wikis , are also a common contributer to circular reporting . as more writers come to rely on such pages for quick information , an unverified fact in a wiki page can make its way into a published article that may later be added as a citation for the very same wiki information , making it much harder to debunk . recent advances in communication technology have had immeasurable benefits in breaking down the barriers between information and people . but our desire for quick answers may overpower the desire to be certain of their validity . and when this bias can be multiplied by billions of people around the world , nearly instantaneously , more caution is in order . avoiding sensationalist media , searching for criticisms of suspicious information , and tracing the original source of a report can help slow down a lie , giving the truth more time to put on its shoes .
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for example , a joke article in the reputable british medical journal entitled `` energy expenditure in adolescents playing new generation computer games , '' has been referenced in serious science publications over 400 times . user-generated content , such as wikis , are also a common contributer to circular reporting . as more writers come to rely on such pages for quick information , an unverified fact in a wiki page can make its way into a published article that may later be added as a citation for the very same wiki information , making it much harder to debunk .
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circular reporting is n't limited to large-scale media and news . how does circular reporting apply to rumors and gossip ?
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we 've all seen movies about terrible insects from outer space or stories of abduction by little green men , but the study of life in the universe , including the possibility of extraterrestrial life , is also a serious , scientific pursuit . astrobiology draws on diverse fields , such as physics , biology , astronomy , and geology , to study how life was formed on earth , how it could form elsewhere , and how we might detect it . many ancient religions described other worlds inhabited by known human beings , but these are more like mythical realms or parallel universes than other planets existing in the same physical world . it is only within the last century that scientists have been able to seriously undertake the search for extraterrestrial life . we know that at the most basic level organisms on earth need three things : liquid water , a source of energy , and organic , carbon-based material . we also know that the earth is just the right distance from the sun , so as not to be either frozen or molten . so , planets within such a habitable range from their own stars may be able to support life . but while we used to think that life could only exist in such earth-like environments , one of the most amazing discoveries of astrobiology has been just how versatile life is . we now know that life can thrive in some of the most extreme environments that 'd be fatal for most known organisms . life is found everywhere , from black smoke of hydrothermal vents in the dark depths of earth 's oceans , to bubbling , hot , acidic springs on the flanks of volcanoes , to high up in the atmosphere . organisms that live in these challenging environments are called extremophiles , and they can survive at extremes of temperature , pressure , and radiation , as well as salinity , acidity , and limited availability of sunlight , water , or oxygen . what is most remarkable about these extremophiles is that they are found thriving in environments that mimic those on alien worlds . one of the most important of these worlds is our red and dusty neighbor , mars . today , astrobiologists are exploring places where life might once have existed on mars using nasa 's curiosity rover . one of these is gale crater , an impact crater created when a meteor hit the surface of mars nearly 3.8 billions years ago . evidence from orbit suggest past traces of water , which means the crater might once have supported life . planets are not the only places astrobiologists are looking at . for example , europa , one of the moons of jupiter , and enceladus and titan , two of saturn 's moons , are all exciting possibilities . although these moons are extremely cold and two are covered in thick ice , there is evidence of liquid oceans beneath the shell . could life be floating around in these oceans , or could it be living around black smoker vents at the bottom ? titan is particularly promising as it has an atmosphere and earth-like lakes , seas , and rivers flowing across the surface . it is very cold , however , too cold for liquid water , so these rivers may instead be flowing with liquid hydrocarbons such as methane and ethane . these are composed of hydrogen , and , more importantly , carbon , which is the basic building block of all life as we know it . so , could life be found in these lakes ? although instruments are being designed to study these distant worlds , it takes many years to build them and even longer to get them where they need to be . in the meantime , astrobiologists work in our own natural laboratory , the earth , to learn about all the weird and wonderful forms of life that can exist and to help us one day answer one of humanity 's oldest questions : are we alone ?
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life is found everywhere , from black smoke of hydrothermal vents in the dark depths of earth 's oceans , to bubbling , hot , acidic springs on the flanks of volcanoes , to high up in the atmosphere . organisms that live in these challenging environments are called extremophiles , and they can survive at extremes of temperature , pressure , and radiation , as well as salinity , acidity , and limited availability of sunlight , water , or oxygen . what is most remarkable about these extremophiles is that they are found thriving in environments that mimic those on alien worlds .
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extremophiles can survive at extremes of temperature , pressure , salinity , acidity , water and oxygen . what are some of the environments on the earth where we could find extremophiles ?
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translator : andrea mcdonough reviewer : bedirhan cinar what does `` going viral '' on the internet really mean , and why does it happen so quickly ? why is a financial institution too big to fail ? how does a virus in africa end up in the united states in a matter of hours ? why are facebook and google such powerful companies at creating global connections ? well , in a word : networks . but what are networks ? everyone knows about their social network , but there are all different kinds of networks you probably have n't thought about . networks are collections of links which combine by specific rules and behaviors if they are alive . we say that networks are alive because they are in constant change . over time , the connections within a network migrate and concentrate in new places , forming evolving structures . how the evolution and concentration of constantly changing connections occurs is the subject of a whole discipline called network theory . we can think of networks as neighborhoods . neighborhoods are defined by maps . a google map demonstrates the relationship between locations in exactly the same fashion a network connects hubs and nodes , using streets as links to connect neighborhoods . the reason a network can expand and evolve so quickly is based upon a mathematical concept called power functions . a power function is a mathematical amplification mechanism , which over specific and very small ranges , accelerates changes logarithmically . that is , a very small change in one parameter produces a huge change in another over a very specific range of values . an example of how network structure emerges is the algorithm used by google . as the number of links around a search term , say `` friends '' , increases , connections begin to form among millions of different searches using the term `` friend '' . what google has cleverly accomplished is a real-time mathematical model for how to predict the emergence of growing connections among billions of search terms . the algorithm google derived collects the number of references to any search object . as references to a search object increase , the number of links also increases , creating a node . as the node increases in size , it eventually becomes a hub , which links to many nodes . networks will continue to emerge as new ways of connecting and creating neighborhoods are defined . perhaps you can begin to see why networks are so powerful . as google continues to collect the billions of daily searches , new clusters of links will rapidly emerge , forming additional and growing networks . despite the logarithmic expansion of your network , the laws of six degrees of separation still apply . therefore , if you explore a close friend or acquaintances in you facebook network , everyone on average will be separated by six individuals or less and a map of your social network will create neighborhoods linked by common connections among friends .
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networks are collections of links which combine by specific rules and behaviors if they are alive . we say that networks are alive because they are in constant change . over time , the connections within a network migrate and concentrate in new places , forming evolving structures .
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why do we say that networks are alive ?
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can plants talk to each other ? it certainly does n't seem that way . plants do n't have complex sensory or nervous systems like animals do , and they look pretty passive , basking in the sun , and responding instinctively to inputs like light and water . but odd as it sounds , plants can communicate with each other . just like animals , plants produce all kinds of chemical signals in response to their environments , and they can share those signals with each other , especially when they 're under attack . these signals take two routes : through the air , and through the soil . when plant leaves get damaged , whether by hungry insects or an invading lawn mower , they release plumes of volatile chemicals . they 're what 's responsible for the smell of freshly cut grass . certain kinds of plants , like sagebrush and lima beans , are able to pick up on those airborne messages and adjust their own internal chemistry accordingly . in one experiment , sagebrush leaves were deliberately damaged by insects or scissor-wielding scientists . throughout the summer , other branches on the same sagebrush plant got eaten less by insects wandering through , and so did branches on neighboring bushes , suggesting that they had beefed up their anti-insect defenses . even moving the air from above a clipped plant to another one made the second plant more insect-resistant . these airborne cues increase the likelihood of seedling survival , and made adult plants produce more new branches and flowers . but why would a plant warn its neighbors of danger , especially if they 're competing for resources ? well , it might be an accidental consequence of a self-defense mechanism . plants ca n't move information through their bodies as easily as we can , especially if water is scarce . so plants may rely on those airborne chemicals to get messages from one part of a plant to another . nearby plants can eavesdrop on those signals , like overhearing your neighbor sneeze and stocking up on cold medicine . different plants convey those warnings using different chemical languages . individual sagebrush plants in the same meadow release slightly different sets of alarm chemicals . the makeup of that cocktail influences the effectiveness of communication . the more similar two plants ' chemical fingerprints are , the more fluently they can communicate . a plant will be most sensitive to the cues emitted by its own leaves . but because these chemicals seem to be inherited , like human blood types , sagebrush plants communicate more effectively with relatives than with strangers . but sometimes , even other species can benefit . tomato and tobacco plants can both decipher sagebrush warning signals . plants do n't have to rely solely on those airborne broadcasts . signals can travel below the soil surface , too . most plants have a symbiotic relationship with fungi , which colonize the plants ' roots and help them absorb water and nutrients . these fungal filaments form extensive networks that can connect separate plants , creating an underground super highway for chemical messages . when a tomato plant responds to blight by acitvating disease-fighting genes and enzymes , signaling molecules produced by its immune system can travel to a healthy plant and prompt it to turn on its immune system , too . these advance warnings increase the plants chance of survival . bean plants also eavesdrop on each other 's health through these fungal conduits . an aphid investation in one plant triggers its neighbor to ramp up production of compounds that repel aphids and attract aphid-eating wasps . if you think of communication as an exchange of information , then plants seem to be active communicators . they 're sending , receiving , and responding to signals without making a sound , and without brains , noses , dictionaries , or the internet . and if we can learn to speak to them on their terms , we may gain a powerful new tool to protect crops and other valuable species . it all makes you wonder what else are we missing ?
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even moving the air from above a clipped plant to another one made the second plant more insect-resistant . these airborne cues increase the likelihood of seedling survival , and made adult plants produce more new branches and flowers . but why would a plant warn its neighbors of danger , especially if they 're competing for resources ?
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when plants emit cues , the information in those cues becomes available :
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honeybees are fascinating creatures for a number of reasons : their incredible work ethic , the sugary sweet syrup they produce and their intricate social structure . but another reason is that honeybees are , in fact , excellent mathematicians . scientists claim the tiny insects can calculate angles , and can even comprehend the roundness of the earth . but there 's particular mathematical bee genius behind the most important aspect of honeybee life : the hive . just like humans , bees need food and shelter to stay alive . the hive is not only the bees ' home , but doubles as a place to store their honey . since it 's so central to survival , honeybees have to perfect the hive 's architectural design . if you examine any piece of honeycomb , you 'll see that it 's constructed from tightly packed hexagonal , or six-sided , cells . of all the possible designs , why do honeybees choose this one ? to understand , you need to think like a bee . bees need a secure place for their entire colony to live . similarly , there needs to be a place where their nectar can be stored and ripened suitably until it turns into honey . that means there 's a need for some serious space efficiency . a good solution is to build little storage units , or cells , just big enough for a bee to fit into , which can also double as the containers in which nectar is stored : the bees ' very own honey jars . the next thing , is to decide what the little cells should be made out of . bees do n't have beaks or arms to pick up things , but they are capable of producing wax . the thing is , producing it is a lot of hard work . bees have to consume 8 ounces of honey to produce just 1 ounce of wax . so they do n't want to waste it . so , they need a design that allows them to store the largest possible amount of honey using the least amount of wax . what shape does that ? imagining for a minute that all bees had to attend architecture academy and go to math class . let 's say they asked their geometry teacher , `` what shape would give us the most space to store our honey , but require the least amount of wax ? '' and then geometry teacher replied , `` the shape that you 're seeking is the circle . '' leaving the bees to return to their trial construction site and begin building their honeycomb using circular cells . after a while , some of them might have noticed a problem with their design : small gaps between the cells . `` we ca n't even fit in there ! that 's wasted space ! '' they might have thought . so , ignoring the geometry lesson , and taking matters into their own hands , the bees went back to the drawing board to rethink their beehive design . one suggested triangles , `` we can use triangles . look ! they fit together perfectly . '' another bee suggested squares . finally , a third bee piped up and said , `` pentagons do n't seem to work , but hexagons do ! we want the one that will use the least amount of wax and be able to store the most amount of honey . yes , i think that 's the hexagon . '' `` why ? '' `` it looks more like the circle than the others . '' `` but how do we know for sure ? '' to find out , the industrious insect architects calculated the areas of the triangle , the square and the hexagon and found that the hexagon was , in fact , the shape that gave them the most storage space . they agreed on an ideal size and returned to work . the space efficient comb that is a bee 's trademark today , is probably the result of this trial and error , but over long periods of evolutionary history . however , it paid off . peek into any hive -- with your protective goggles and netting on , of course -- and you 'll see the end result : a beautiful compact honeycomb that any architect would have be proud to design .
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`` why ? '' `` it looks more like the circle than the others . '' `` but how do we know for sure ? ''
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as you discovered in problem 6 , if you keep the perimeter the same , you will increase the area of regular polygons as you add more sides . using this understanding , explain why it makes sense that a circle maximizes the area for any given perimeter .
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translator : andrea mcdonough reviewer : jessica ruby there are still lots of things about space that we may never be able to answer , like is time travel possible ? or are aliens living somewhere else in the milky way ? but there is one thing i believe about space : space is trying to kill me . space is n't out to get me personally . it 's also trying to kill you and everybody else . think about it . space does n't naturally have what we need to survive when we travel there : no air , it 's too hot or too cold , no ozone to protect us from those nasty uv rays , either . this all sounds bad , but what can space really do to me if i stay on earth ? what we need to understand is that objects in space can cause people to think their days are numbered , even when there are events on earth that can hurt or kill us before something from space does . so , what are the odds that one of these objects will really affect earth and you and me in our lifetime ? well , we can take what we know about the universe to try and figure that out . you might have heard stories about asteroids hitting the earth . that would be pretty bad . scientists think asteroids might have killed off most of the dinosaurs . sounds like something we should worry about , right ? well , astronomers can now watch asteroids in space and see them coming using complex computer models to predict the deadly rock 's path . for a while , the reported odds that asteroid apophis would strike earth in 2036 were once 1 in 625 . but , after updating their data , astronomers now say the chances are extremely low . okay , what about the sun ? hollywood movies like to pick on our sun by showing earth destroyed by solar flares or the sun dying out , which would cause earth to freeze . astronomers predict our sun contains enough gas to make energy for another 3 to 5 billion years . so , in 3 to 5 billion years , if people still exist on earth , they 'll have to deal with that . but today , well , we 're safe . sometimes the sun does shoot flares at earth , but the magnetic fields surrounding our planet blocks most of that radiation . the radiation that does get through creates things like the aurora borealis . gigantic solar flares can mess with our satellites and electrical equipment , but the chances of it killing you are pretty slim . okay , what about that supermassive black hole in the middle of our galaxy ? what happens to earth , and us , when it pulls us in ? after all , it is supermassive . nope , not going to happen . that 's one big object that ca n't bother us . how can we be so sure ? our solar system is on the edge of the milky way while the nearest supermassive black hole is about 26,000 light years from earth . that means we are n't on that black hole 's menu . so , you still think space objects are trying to kill you even after what i 've told you so far ? i think i 've even convinced myself that odds are really good that space and the objects up there wo n't kill me after all . but i 'll probably keep looking up just to make sure nothing is headed my way .
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translator : andrea mcdonough reviewer : jessica ruby there are still lots of things about space that we may never be able to answer , like is time travel possible ? or are aliens living somewhere else in the milky way ?
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research how astronauts are able to be protected while they live and travel in space .
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to understand climate change , think of the game `` tetris . '' for eons , earth has played a version of this game with blocks of carbon . they enter the atmosphere as carbon dioxide gas from volcanoes , decaying plant matter , breathing creatures and the surface of the sea . and they leave the atmosphere when they 're used by plants during photosynthesis , absorbed back into the ocean , or stored in soil and sediment . this game of tetris is called the carbon cycle , and it 's the engine of life on earth . what 's the connection to climate ? well , when that carbon dioxide is in the air , waiting to be reabsorbed , it traps a portion of the sun 's heat , which would otherwise escape to space . that 's why carbon dioxide is called a greenhouse gas . it creates a blanket of warmth , known as the greenhouse effect , that keeps our earth from freezing like mars . the more carbon dioxide blocks hang out in the atmosphere waiting to be cleared , the warmer earth becomes . though the amount of carbon in the atmosphere has varied through ice ages and astroid impacts , over the past 8,000 years the stable climate we know took shape , allowing human civilization to thrive . but about 200 years ago , we began digging up that old carbon that had been stored in the soil . these fossil fuels , coal , oil and natural gas are made from the buried remains of plants and animals that died long before humans evolved . the energy stored inside them was able to power our factories , cars and power plants . but burning these fuels also injected new carbon blocks into earth 's tetris game . at the same time , we cleared forests for agriculture , reducing the earth 's ability to remove the blocks . and since 1750 , the amount of carbon in the atmosophere has increased by 40 % , and shows no sign of slowing . just like in tetris , the more blocks pile up , the harder it becomes to restore stability . the extra carbon dioxide in the atmosphere accelerates the greenhouse effect by trapping more heat near the surface and causing polar ice caps to melt . and the more they melt , the less sunlight they 're able to reflect , making the oceans warm even faster . sea levels rise , coastal populations are threatened with flooding , natural ecosystems are disrupted , and the weather becomes more extreme over time . climate change may effect different people and places in different ways . but , ultimately , it 's a game that we 're all stuck playing . and unlike in tetris , we wo n't get a chance to start over and try again .
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but about 200 years ago , we began digging up that old carbon that had been stored in the soil . these fossil fuels , coal , oil and natural gas are made from the buried remains of plants and animals that died long before humans evolved . the energy stored inside them was able to power our factories , cars and power plants .
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which of the following energy sources uses fossil fuels ?
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are you afraid of black cats ? would you open an umbrella indoors ? and how do you feel about the number thirteen ? whether or not you believe in them , you 're probably familiar with a few of these superstitions . so how did it happen that people all over the world knock on wood , or avoid stepping on sidewalk cracks ? well , although they have no basis in science , many of these weirdly specific beliefs and practices do have equally weird and specific origins . because they involve supernatural causes , it 's no surprise that many superstitions are based in religion . for example . the number thirteen was associated with the biblical last supper , where jesus christ dined with his twelve disciples just before being arrested and crucified . the resulting idea that having thirteen people at a table was bad luck eventually expanded into thirteen being an unlucky number in general . now , this fear of the number thirteen , called triskaidekaphobia , is so common that many buildings around the world skip the thirteenth floor , with the numbers going straight from twelve to fourteen . of course , many people consider the story of the last supper to be true but other superstitions come from religious traditions that few people believe in or even remember . knocking on wood is thought to come from the folklore of the ancient indo-europeans or possibly people who predated them who believed that trees were home to various spirits . touching a tree would invoke the protection or blessing of the spirit within . and somehow , this tradition survived long after belief in these spirits had faded away . many superstitions common today in countries from russia to ireland are thought to be remnants of the pagan religions that christianity replaced . but not all superstitions are religious . some are just based on unfortunate coincidences and associations . for example , many italians fear the number 17 because the roman numeral xvii can be rearranged to form the word vixi , meaning my life had ended . similarly , the word for the number four sounds almost identical to the word for death in cantonese , as well as languages like japanese and korean that have borrowed chinese numerals . and since the number one also sounds like the word for must , the number fourteen sounds like the phrase must die . that 's a lot of numbers for elevators and international hotels to avoid . and believe it or not , some superstitions actually make sense , or at least they did until we forgot their original purpose . for example , theater scenery used to consist of large painted backdrops , raised and lowered by stagehands who would whistle to signal each other . absentminded whistles from other people could cause an accident . but the taboo against whistling backstage still exists today , long after the stagehands started using radio headsets . along the same lines , lighting three cigarettes from the same match really could cause bad luck if you were a soldier in a foxhole where keeping a match lit too long could draw attention from an enemy sniper . most smokers no longer have to worry about snipers , but the superstition lives on . so why do people cling to these bits of forgotten religions , coincidences , and outdated advice ? are n't they being totally irrational ? well , yes , but for many people , superstitions are based more on cultural habit than conscious belief . after all , no one is born knowing to avoid walking under ladders or whistling indoors , but if you grow up being told by your family to avoid these things , chances are they 'll make you uncomfortable , even after you logically understand that nothing bad will happen . and since doing something like knocking on wood does n't require much effort , following the superstition is often easier than consciously resisting it . besides , superstitions often do seem to work . maybe you remember hitting a home run while wearing your lucky socks . this is just our psychological bias at work . you 're far less likely to remember all the times you struck out while wearing the same socks . but believing that they work could actually make you play better by giving you the illusion of having greater control over events . so in situations where that confidence can make a difference , like sports , those crazy superstitions might not be so crazy after all .
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the resulting idea that having thirteen people at a table was bad luck eventually expanded into thirteen being an unlucky number in general . now , this fear of the number thirteen , called triskaidekaphobia , is so common that many buildings around the world skip the thirteenth floor , with the numbers going straight from twelve to fourteen . of course , many people consider the story of the last supper to be true but other superstitions come from religious traditions that few people believe in or even remember .
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triskaidekaphobia is the fear of :
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they say that if walls could talk , each building would have a story to tell , but few would tell so many fascinating stories in so many different voices as the hagia sophia , or holy wisdom . perched at the crossroads of continents and cultures , it has seen massive changes from the name of the city where it stands , to its own structure and purpose . and today , the elements from each era stand ready to tell their tales to any visitor who will listen . even before you arrive at the hagia sophia , the ancient fortifications hint at the strategic importance of the surrounding city , founded as byzantium by greek colonists in 657 bce . and successfully renamed as augusta antonia , new rome and constantinople as it was conquered , reconquered , destroyed and rebuilt by various greek , persian and roman rulers over the following centuries . and it was within these walls that the first megale ekklesia , or great church , was built in the fourth century . though it was soon burned to the ground in riots , it established the location for the region 's main religious structure for centuries to come . near the entrance , the marble stones with reliefs are the last reminders of the second church . built in 415 ce , it was destroyed during the nika riots of 532 when angry crowds at a chariot race nearly overthrew the emperor , justinian the first . having barely managed to retain power , he resolved to rebuild the church on a grander scale , and five years later , the edifice you see before you was completed . as you step inside , the stones of the foundation and walls murmur tales from their homelands of egypt and syria , while columns taken from the temple of artemis recall a more ancient past . runic inscriptions carved by the vikings of the emperor 's elite guard carry the lore of distant northern lands . but your attention is caught by the grand dome , representing the heavens . reaching over 50 meters high and over 30 meters in diameter and ringed by windows around its base , the golden dome appears suspended from heaven , light reflecting through its interior . beneath its grandiose symbolism , the sturdy reinforcing corinthian columns , brought from lebanon after the original dome was partially destroyed by an earthquake in 558 ce , quietly remind you of its fragility and the engineering skills such a marvel requires . if a picture is worth a thousand words , the mosaics from the next several centuries have the most to say not only about their biblical themes , but also the byzantine emperors who commissioned them , often depicted along with christ . but beneath their loud and clear voices , one hears the haunting echoes of the damaged and missing mosaics and icons , desecrated and looted during the latin occupation in the fourth crusade . within the floor , the tomb inscription of enrico dandolo , the venetian ruler who commanded the campaign , is a stark reminder of those 57 years that hagia sophia spent as a roman catholic church before returning to its orthodox roots upon the byzantine reconquest . but it would not remain a church for long . weakened by the crusades , constantinople fell to the ottomans in 1453 and would be known as istanbul thereafter . after allowing his soldiers three days of pillage , sultan mehmed the second entered the building . though heavily damaged , its grandeur was not lost on the young sultan who immediately rededicated it to allah , proclaiming that it would be the new imperial mosque . the four minarets built over the next century are the most obvious sign of this era , serving as architectural supports in addition to their religious purpose . but there are many others . ornate candle holders relate suleiman 's conquest of hungary , while giant caligraphy discs hung from the ceiling remind visitors for the first four caliphs who followed muhammad . though the building you see today still looks like a mosque , it is now a museum , a decision made in 1935 by kemal ataturk , the modernizing first president of turkey following the ottoman empire 's collapse . it was this secularization that allowed for removal of the carpets hiding the marble floor decorations and the plaster covering the christian mosaics . ongoing restoration work has allowed the multiplicity of voices in hagia sophia 's long history to be heard again after centuries of silence . but conflict remains . hidden mosaics cry out from beneath islamic calligraphy , valuable pieces of history that can not be uncovered without destroying others . meanwhile , calls sound from both muslim and christian communities to return the building to its former religious purposes . the story of the divine wisdom may be far from over , but one can only hope that the many voices residing there will be able to tell their part for years to come .
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if a picture is worth a thousand words , the mosaics from the next several centuries have the most to say not only about their biblical themes , but also the byzantine emperors who commissioned them , often depicted along with christ . but beneath their loud and clear voices , one hears the haunting echoes of the damaged and missing mosaics and icons , desecrated and looted during the latin occupation in the fourth crusade . within the floor , the tomb inscription of enrico dandolo , the venetian ruler who commanded the campaign , is a stark reminder of those 57 years that hagia sophia spent as a roman catholic church before returning to its orthodox roots upon the byzantine reconquest .
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during the 4th crusade of the latin occupation ________ .
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the world wide web , where you 're likely watching this video , is used by millions of people every day for everything from checking the weather , ordering food , and chatting with friends to raising funds , sharing news , or starting revolutions . we use it from our computers , our phones , even our cars . it 's just there , all around us , all the time . but what is it exactly ? well first of all , the world wide web is not the internet , even though the terms are often used interchangeably . the internet is simply the way computers connect to each other in order to share information . when the internet first emerged , computers actually made direct calls to each other . today , networks are all around us , so computers can communicate seamlessly . the communication enabled through the internet has many uses , such as email , file transfer , and conferencing . but the most common use is accessing the world wide web . think of the web as a bunch of skyscrapers , each representing a web server , a computer always connected to the internet , specifically designed to store information and share it . when someone starts a website , they are renting a room in this skyscraper , filling it with information and linking that information together in an organized way for others to access . the people who own these skyscrapers and rent space in them are called web hosts , but anyone can set up a web server with the right equipment a bit of know-how . there 's another part to having a website , without which we would be lost in the city with no way of finding what we need . this is the website address , which consists of domain names . just like with a real life address , a website address lets you get where you want to go . the information stored in the websites is in web languages , such as html and javascript . when we find the website we 're looking for , our web browser is able to take all the code on the site and turn it into words , graphics , and videos . we do n't need to know any special computer languages because the web browser creates a graphic interface for us . so , in a lot of ways , the world wide web is a big virtual city where we communicate with each other in web languages , with browsers acting as our translators . and just like no one owns a city , no one owns the web ; it belongs to all of us . anyone can move in and set up shop . we might have to pay an internet service provider to gain access , a hosting company to rent web space , or a registrar to reserve our web address . like utility companies in a city , these companies provide crucial services , but in the end , not even they own the web . but what really makes the web so special lies in its very name . prior to the web , we used to consume most information in a linear fashion . in a book or newspaper article , each sentence was read from beginning to end , page by page , in a straight line until you reached the end . but that is n't how our brains actually work . each of our thoughts is linked to other thoughts , memories , and emotions in a loose interconnected network , like a web . tim berners-lee , the father of the world wide web , understood that we needed a way to organize information that mirrored this natural arrangement . and the web accomplishes this through hyperlinks . by linking several pages within a website or even redirecting you to other websites to expand on information or ideas immediately as you encounter them , hyperlinks allow the web to operate along the same lines as our thought patterns . the web is so much a part of our lives because in content and structure , it reflects both the wider society and our individual minds . and it connects those minds across all boundaries , not only enthnicity , gender , and age but even time and space .
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each of our thoughts is linked to other thoughts , memories , and emotions in a loose interconnected network , like a web . tim berners-lee , the father of the world wide web , understood that we needed a way to organize information that mirrored this natural arrangement . and the web accomplishes this through hyperlinks .
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how does the web organize information so that it resembles the way we think ?
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imagine an island where 100 people , all perfect logicians , are imprisoned by a mad dictator . there 's no escape , except for one strange rule . any prisoner can approach the guards at night and ask to leave . if they have green eyes , they 'll be released . if not , they 'll be tossed into the volcano . as it happens , all 100 prisoners have green eyes , but they 've lived there since birth , and the dictator has ensured they ca n't learn their own eye color . there are no reflective surfaces , all water is in opaque containers , and most importantly , they 're not allowed to communicate among themselves . though they do see each other during each morning 's head count . nevertheless , they all know no one would ever risk trying to leave without absolute certainty of success . after much pressure from human rights groups , the dictator reluctantly agrees to let you visit the island and speak to the prisoners under the following conditions : you may only make one statement , and you can not tell them any new information . what can you say to help free the prisoners without incurring the dictator 's wrath ? after thinking long and hard , you tell the crowd , `` at least one of you has green eyes . '' the dictator is suspicious but reassures himself that your statement could n't have changed anything . you leave , and life on the island seems to go on as before . but on the hundredth morning after your visit , all the prisoners are gone , each having asked to leave the previous night . so how did you outsmart the dictator ? it might help to realize that the amount of prisoners is arbitrary . let 's simplify things by imagining just two , adria and bill . each sees one person with green eyes , and for all they know , that could be the only one . for the first night , each stays put . but when they see each other still there in the morning , they gain new information . adria realizes that if bill had seen a non-green-eyed person next to him , he would have left the first night after concluding the statement could only refer to himself . bill simultaneously realizes the same thing about adria . the fact that the other person waited tells each prisoner his or her own eyes must be green . and on the second morning , they 're both gone . now imagine a third prisoner . adria , bill and carl each see two green-eyed people , but are n't sure if each of the others is also seeing two green-eyed people , or just one . they wait out the first night as before , but the next morning , they still ca n't be sure . carl thinks , `` if i have non-green eyes , adria and bill were just watching each other , and will now both leave on the second night . '' but when he sees both of them the third morning , he realizes they must have been watching him , too . adria and bill have each been going through the same process , and they all leave on the third night . using this sort of inductive reasoning , we can see that the pattern will repeat no matter how many prisoners you add . the key is the concept of common knowledge , coined by philosopher david lewis . the new information was not contained in your statement itself , but in telling it to everyone simultaneously . now , besides knowing at least one of them has green eyes , each prisoner also knows that everyone else is keeping track of all the green-eyed people they can see , and that each of them also knows this , and so on . what any given prisoner does n't know is whether they themselves are one of the green-eyed people the others are keeping track of until as many nights have passed as the number of prisoners on the island . of course , you could have spared the prisoners 98 days on the island by telling them at least 99 of you have green eyes , but when mad dictators are involved , you 're best off with a good headstart .
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after thinking long and hard , you tell the crowd , `` at least one of you has green eyes . '' the dictator is suspicious but reassures himself that your statement could n't have changed anything . you leave , and life on the island seems to go on as before .
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what was it about your statement that changed the situation on the island ?
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there 's an organism that changed the world . it caused both the first mass extinction in earth 's history and also paved the way for complex life . how ? by sending the first free oxygen molecules into our atmosphere , and they did all this as single-celled life forms . they 're cyanobacteria , and the story of these simple organisms that do n't even have nuclei or any other organelles is a pivotal chapter in the story of life on earth . earth 's atmosphere was n't always the oxygen-rich mixture we breathe today . 3.5 billion years ago , the atmosphere was mostly nitrogen , carbon dioxide , and methane . almost all oxygen was locked up in molecules like water , not floating around in the air . the oceans were populated by anaerobic microbes . those are simple , unicellular life forms that thrive without oxygen and get energy by scavenging what molecules they find . but somewhere between 2.5 and 3.5 billion years ago , one of these microbial species , probably floating on the surface of the ocean , evolved a new ability : photosynthesis . structures in their cell membrane could harness the energy from sunlight to turn carbon dioxide and water into oxygen gas and sugars , which they could use for energy . those organisms were the ancestors of what we now call cyanobacteria . their bluish color comes from the blue-green pigments that capture the sunlight they need . photosynthesis gave those ancient bacteria a huge advantage over other species . they could now produce their own energy from an almost endless supply of raw ingredients , so their populations exploded and they started polluting the atmosphere with a new waste product : oxygen . at first , the trickle of extra oxygen was soaked up by chemical reactions with iron or decomposing cells , but after a few hundred million years , the cyanobacteria were producing oxygen faster than it could be absorbed , and the gas started building up in the atmosphere . that was a big problem for the rest of earth 's inhabitants . oxygen-rich air was actually toxic to them . the result ? about 2.5 billion years ago was a mass extinction of virtually all life on earth , which barely spared the cyanobacteria . geologists call this the great oxygenation event , or even the oxygen catastrophe . that was n't the only problem . methane had been acting as a potent greenhouse gas that kept the earth warm , but now , the extra oxygen reacted with methane to form carbon dioxide and water , which do n't trap as much heat . the thinner atmospheric blanket caused earth 's first , and possibly longest , ice age , the huronian glaciation . the planet was basically one giant snowball for several hundred million years . eventually , life adjusted . aerobic organisms , which can use oxygen for energy , started sopping up some of the excess gas in the atmosphere . the oxygen concentration rose and fell until eventually it reached the approximate 21 % we have today . and being able to use the chemical energy in oxygen gave organisms the boost they needed to diversify and evolve more complex forms . cyanobacteria had a part to play in that story , too . hundreds of millions of years ago , some other prehistoric microbe swallowed a cyanobacterium whole in a process called endosymbiosis . in doing so , that microbe acquired its own internal photosynthesis factory . this was the ancestor of plant cells . and cyanobacteria became chloroplasts , the organelles that carry out photosynthesis today . cyanobacteria are still around in almost every environment on earth : oceans , fresh water , soil , antarctic rocks , sloth fur . they still pump oxygen into the atmosphere , and they also pull nitrogen out to fertilize the plants they helped create . we would n't recognize life on earth without them . but also thanks to them , we almost did n't have life on earth at all .
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methane had been acting as a potent greenhouse gas that kept the earth warm , but now , the extra oxygen reacted with methane to form carbon dioxide and water , which do n't trap as much heat . the thinner atmospheric blanket caused earth 's first , and possibly longest , ice age , the huronian glaciation . the planet was basically one giant snowball for several hundred million years .
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the huronian glaciation :
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somewhere out there in that vast universe , there must surely be countless other planets teeming with life , but why do n't we see any evidence of it ? well , this is the famous question asked by enrico fermi in 1950 : `` where is everybody ? '' conspiracy theorists claim that ufos are visiting all the time and the reports are just being covered up , but honestly , they are n't very convincing . but that leaves a real riddle . in the past year , the kepler space observatory has found hundreds of planets just around nearby stars , and if you extrapolate that data , it looks like there could be half a trillion planets just in our own galaxy . if any one in 10,000 has conditions that might support a form of life , that 's still 50 million possible life-harboring planets right here in the milky way . so here 's the riddle . our earth did n't form until about 9 billion years after the big bang . countless other planets in our galaxy should have formed earlier and given life a chance to get underway billions or certainly many millions of years earlier than happened on earth . if just a few of them had spawned intelligent life and started creating technologies , those technologies would have had millions of years to grow in complexity and power . on earth , we 've seen how dramatically technology can accelerate in just 100 years . in millions of years , an intelligent alien civilization could easily have spread out across the galaxy , perhaps creating giant energy-harvesting artifacts , or fleets of colonizing spaceships , or glorious works of art that fill the night sky . at the very least , you 'd think they 'd be revealing their presence , deliberately or otherwise , through electromagnetic signals of one kind or another . and yet we see no convincing evidence of any of it . why ? well , there are numerous possible answers , some of them quite dark . maybe a single , superintelligent civilization has indeed taken over the galaxy , and has imposed strict radio silence because it 's paranoid of any potential competitors . it 's just sitting there ready to obliterate anything that becomes a threat . or maybe they 're not that intelligent . or perhaps , the evolution of an intelligence capable of creating sophisticated technology is far rarer than we 've assumed . after all , it 's only happened once on earth in 4 billion years . maybe even that was incredibly lucky . maybe we are the first such civilization in our galaxy . or , perhaps , civilization carries with it the seeds of its own destruction through the inability to control the technologies it creates . but there are numerous more hopeful answers . for a start , we 're not looking that hard , and we 're spending a pitiful amount of money on it . only a tiny fraction of the stars in our galaxy have really been looked at closely for signs of interesting signals . and perhaps , we 're not looking the right way . maybe as civilizations develop , they quickly discover communication technologies far more sophisticated and useful than electromagnetic waves . maybe all the action takes place inside the mysterious recently discovered dark matter , or dark energy , that appear to account for most of the universe 's mass . or maybe we 're looking at the wrong scale . perhaps intelligent civilizations come to realize that life is ultimately just complex patterns of information interacting with each other in a beautiful way , and that can happen more efficiently at a small scale . so just as on earth , clunky stereo systems have shrunk to beautiful , tiny ipods , maybe intelligent life itself , in order to reduce its footprint on the environment , has turned itself microscopic , so the solar system might be teeming with aliens , and we 're just not noticing them . maybe the very ideas in our heads are a form of alien life . well , okay , that 's a crazy thought . the aliens made me say it . but it is cool that ideas do seem to have a life all of their own , and that they outlive their creators . maybe biological life is just a passing phase . well , within the next 15 years , we could start seeing real spectroscopic information from promising nearby planets that will reveal just how life-friendly they might be . and meanwhile seti , the search for extra-terrestrial intelligence , is now releasing its data to the public so that millions of citizen scientists , maybe including you , can bring the power of the crowd to join the search . and here on earth , amazing experiments are being done to try to create life from scratch , life that might be very different from the dna forms we know . all of this will help us understand whether the universe is teeming with life or , whether indeed , it 's just us . either answer , in its own way , is awe-inspiring , because even if we are alone , the fact that we think and dream , and ask these questions might yet turn out to be one of the most important facts about the universe . and i have one more piece of good news for you . the quest for knowledge and understanding never gets dull . it does n't . it 's actually the opposite . the more you know , the more amazing the world seems . and it 's the crazy possibilities , the unanswered questions , that pull us forward . so , stay curious .
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well , okay , that 's a crazy thought . the aliens made me say it . but it is cool that ideas do seem to have a life all of their own , and that they outlive their creators .
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seti recently made its data public in order to :
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in 1800 , the explorer alexander von humboldt witnessed a swarm of electric eels leap out of the water to defend themselves against oncoming horses . most people thought the story so unusual that humboldt made it up . but fish using electricity is more common than you might think ; and yes , electric eels are a type of fish . underwater , where light is scarce , electrical signals offer ways to communicate , navigate , and find—plus , in rare cases , stun—prey . nearly 350 species of fish have specialized anatomical structures that generate and detect electrical signals . these fish are divided into two groups , depending on how much electricity they produce . scientists call the first group the weakly electric fish . structures near their tails called electric organs produce up to a volt of electricity , about two-thirds as much as a aa battery . how does this work ? the fish 's brain sends a signal through its nervous system to the electric organ , which is filled with stacks of hundreds or thousands of disc-shaped cells called electrocytes . normally , electrocytes pump out sodium and potassium ions to maintain a positive charge outside and negative charge inside . but when the nerve signal arrives at the electrocyte , it prompts the ion gates to open . positively charged ions flow back in . now , one face of the electrocyte is negatively charged outside and positively charged inside . but the far side has the opposite charge pattern . these alternating charges can drive a current , turning the electrocyte into a biological battery . the key to these fish 's powers is that nerve signals are coordinated to arrive at each cell at exactly the same time . that makes the stacks of electrocytes act like thousands of batteries in series . the tiny charges from each one add up to an electrical field that can travel several meters . cells called electroreceptors buried in the skin allow the fish to constantly sense this field and the changes to it caused by the surroundings or other fish . the peter ’ s elephantnose fish , for example , has an elongated chin called a schnauzenorgan that 's riddled in electroreceptors . that allows it to intercept signals from other fish , judge distances , detect the shape and size of nearby objects , and even determine whether a buried insect is dead or alive . but the elephantnose and other weakly electric fish do n't produce enough electricity to attack their prey . that ability belongs to the strongly electric fish , of which there are only a handful of species . the most powerful strongly electric fish is the electric knife fish , more commonly known as the electric eel . three electric organs span almost its entire two-meter body . like the weakly electric fish , the electric eel uses its signals to navigate and communicate , but it reserves its strongest electric discharges for hunting using a two-phased attack that susses out and then incapacitates its prey . first , it emits two or three strong pulses , as much as 600 volts . these stimulate the prey 's muscles , sending it into spasms and generating waves that reveal its hiding place . then , a volley of fast , high-voltage discharges causes even more intense muscle contractions . the electric eel can also curl up so that the electric fields generated at each end of the electric organ overlap . the electrical storm eventually exhausts and immobilizes the prey , and the electric eel can swallow its meal alive . the other two strongly electric fish are the electric catfish , which can unleash 350 volts with an electric organ that occupies most of its torso , and the electric ray , with kidney-shaped electric organs on either side of its head that produce as much as 220 volts . there is one mystery in the world of electric fish : why do n't they electrocute themselves ? it may be that the size of strongly electric fish allows them to withstand their own shocks , or that the current passes out of their bodies too quickly . some scientists think that special proteins may shield the electric organs , but the truth is , this is one mystery science still has n't illuminated .
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the electrical storm eventually exhausts and immobilizes the prey , and the electric eel can swallow its meal alive . the other two strongly electric fish are the electric catfish , which can unleash 350 volts with an electric organ that occupies most of its torso , and the electric ray , with kidney-shaped electric organs on either side of its head that produce as much as 220 volts . there is one mystery in the world of electric fish : why do n't they electrocute themselves ?
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how many electric organs do electric eels have ?
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translator : andrea mcdonough reviewer : bedirhan cinar by now , i 'm sure you know that in just about anything you do in life , you need numbers . in particular , though , some fields do n't just need a few numbers , they need lots of them . how do you keep track of all those numbers ? well , mathematicians dating back as early as ancient china came up with a way to represent arrays of many numbers at once . nowadays we call such an array a `` matrix , '' and many of them hanging out together , `` matrices '' . matrices are everywhere . they are all around us , even now in this very room . sorry , let 's get back on track . matrices really are everywhere , though . they are used in business , economics , cryptography , physics , electronics , and computer graphics . one reason matrices are so cool is that we can pack so much information into them and then turn a huge series of different problems into one single problem . so , to use matrices , we need to learn how they work . it turns out , you can treat matrices just like regular numbers . you can add them , subtract them , even multiply them . you ca n't divide them , but that 's a rabbit hole of its own . adding matrices is pretty simple . all you have to do is add the corresponding entries in the order they come . so the first entries get added together , the second entries , the third , all the way down . of course , your matrices have to be the same size , but that 's pretty intuitive anyway . you can also multiply the whole matrix by a number , called a scalar . just multiply every entry by that number . but wait , there 's more ! you can actually multiply one matrix by another matrix . it 's not like adding them , though , where you do it entry by entry . it 's more unique and pretty cool once you get the hang of it . here 's how it works . let 's say you have two matrices . let 's make them both two by two , meaning two rows by two columns . write the first matrix to the left and the second matrix goes next to it and translated up a bit , kind of like we are making a table . the product we get when we multiply the matrices together will go right between them . we 'll also draw some gridlines to help us along . now , look at the first row of the first matrix and the first column of the second matrix . see how there 's two numbers in each ? multiply the first number in the row by the first number in the column : 1 times 2 is 2 . now do the next ones : 3 times 3 is 9 . now add them up : 2 plus 9 is 11 . let 's put that number in the top-left position so that it matches up with the rows and columns we used to get it . see how that works ? you can do the same thing to get the other entries . -4 plus 0 is -4 . 4 plus -3 is 1 . -8 plus 0 is -8 . so , here 's your answer . not all that bad , is it ? there 's one catch , though . just like with addition , your matrices have to be the right size . look at these two matrices . 2 times 8 is 16 . 3 times 4 is 12 . 3 times wait a minute , there are no more rows in the second matrix . we ran out of room . so , these matrices ca n't be multiplied . the number of columns in the first matrix has to be the same as the number of rows in the second matrix . as long as you 're careful to match up your dimensions right , though , it 's pretty easy . understanding matrix multiplication is just the beginning , by the way . there 's so much you can do with them . for example , let 's say you want to encrypt a secret message . let 's say it 's `` math rules '' . though , why anybody would want to keep this a secret is beyond me . letting numbers stand for letters , you can put the numbers in a matrix and then an encryption key in another . multiply them together and you 've got a new encoded matrix . the only way to decode the new matrix and read the message is to have the key , that second matrix . there 's even a branch of mathematics that uses matrices constantly , called linear algebra . if you ever get a chance to study linear algebra , do it , it 's pretty awesome . but just remember , once you know how to use matrices , you can do pretty much anything .
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just like with addition , your matrices have to be the right size . look at these two matrices . 2 times 8 is 16 .
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list the two ways you can multiply matrices , and briefly explain why you ca n't divide two matrices of equal size .
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when you touch an object and it feels warm or cold , what is that really telling you about the object ? here , i have a metal hard drive and a book and i 'm going to ask people to compare their temperatures . which one do you think will feel warmer - the book or the hard drive ? the temperatures ? yeah , tell me if one is hotter or colder or if they 're the same temperature . how do they feel ? this is slightly cooler than this one . oh , that 's warmer . yeah , agreed . i 'd say the hard drive is a lot colder than the book . 'cause the book 's got more knowledge . why do you think that is ? metal 's normally a little bit chillier if you leave it in a colder temperature . what if i said they 're both the same temperature ? what would you say ? i 'd tell you you 're lying . i 'd think you were lying , yeah . well , maybe the way i can prove it is i have an infrared thermometer . what do you think we 're going to see ? i think science might be able to answer that . and i 'm not a scientist ! make a prediction for me . i still think that 's colder . would you bet me money ? i do n't have any cash . let 's measure the temperature of the book . what do you see ? 19.0 . ok. now measure the temperature of that . 19.0 . alright , well , now i believe you . i 'm trying to figure it out , actually . trying to figure out why 'd they be the same temperature . they do n't feel the same temperature , though . so , why does that feel colder if they 're the same ? good one . you know the answer ? i 'm coming to you guys for answers . we 're creatives , not intellectuals . well , create an answer for me ! i 'm not a scientist ! come on , you tell me . i 'll try to answer that question with another little experiment . here is an aluminium block . ooh ! nice and cold . and a plastic block . how do their temperatures compare ? completely different . aluminium 's going to be much colder . yeah ? this actually feels colder . let 's take this to the next level . i 'll put an ice cube on both plates . what will we see ? i 'm guessing it would stay solid on this one and melt on this one . so it 's going to melt on the plastic but stay solid on the aluminium ? yes , but maybe i 'm wrong . that one will melt more quickly than on the aluminium . you 'd think so . yeah , 'cause it 's cold . i think they 're the same . we put an ice cube on each of those . what do you see ? it 's melting quicker on the aluminium . my god , it 's melting ! this is melting quicker than that one , even though this is aluminium and that 's plastic . so which one felt colder ? this one . how does that make sense ? no idea . could aluminium be bad for the environment ? how would aluminium be bad for the environment ? it 's thawing the ice quicker , is n't it ? you want the answer ? yes , please ! it 's about thermoconductivity - the rate at which heat is transferred from one object to another . so when you felt these blocks originally , i know this one felt a lot colder . but you know from the other example we did , that they must both be the same temperature . true . they 've both been outside for a while . we see the aluminium block is melting the ice faster than the plastic block because it 's conducting the heat to the ice cube faster . with the plastic block , it 's a worse thermoconductor . so , heat is being transferred less quickly to this ice block and so it 's staying iced . ok . i believe you . make sense ? yes . definitely . in our first example , the hard drive felt colder , even though it was at the same temperature as the book . that 's because the aluminium conducts heat away from your hand faster than the book conducts heat away from your hand . sure . that seems logical . which makes the hard drive feel colder and the book feel warmer . so when you touch something , you do n't actually feel temperature . you feel the rate at which heat is conducted , either towards or away from you . think about this next time you hop out of the shower in winter . it 's much nicer to stand on the bath mat than on a towel beside it . not because the bath mat is warmer but because it conducts heat less quickly away from you .
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that seems logical . which makes the hard drive feel colder and the book feel warmer . so when you touch something , you do n't actually feel temperature .
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even though the book and the hard drive are the same temperature , why does the hard drive feel colder ?
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translator : andrea mcdonough reviewer : jessica ruby in the 11th and 12th centuries , most english commoners were illiterate . since they had no way to learn the bible , the clergy came up with an inventive solution : they 'd create plays out of certain bible stories so even people who could n't read could learn them . these were called mystery plays because they revealed the mystery of god 's word . at about the same time , the clergy also developed plays about the saints of the church , called miracle plays . in the beginning , the clergy members acted out bible stories on the steps outside the cathedral . the audience reacted so well that soon they needed to move out to the street around the town square . by building moving carts to put on each play and by lining up one after the other , they could put on cycles of stories , which would take the viewer from genesis to revelation . these movable carts , called pageants , looked like huge boxes on wheels . each was two stories tall . the bottom story was curtained off and was used for costumes , props , and dressing . the top platform was the stage for the performance . spectators assembled in various corners of the town , and the pageant would move around in the cycle until the villagers had seen the entire series . soon , the plays required more actors than the clergy could supply . so , by the 13th century , different guilds were asked to be responsible for acting out different parts of the cycle . the assignments were meant to reflect the guilds ' professions . for example , the carpenter 's guild might put on the story of noah 's ark , and the baker 's guild might put on the last supper . can you imagine what might happen to the story if the butcher 's guild put on the crucifixion of christ ? yes , without the clergy , the plays soon started changing from their true bible stories . by the end of the 14th century , a new form of drama , called the morality play , had evolved . faith , truth , charity , and good deeds all became characters on the stage . and , at the same time , the opposite virtues of falsehood , covetousness , worldly flesh , and the devil became the antagonists . the morality plays were allegorical stories in which these characters battled for the control of the soul . audiences loved the immoral characters , and spectators were encouraged to interact with the actors . throwing rotten food and even getting into scuffles with other spectators became very common . the character of the devil often would roam through the crowds and pull unsuspecting watchers into a hell that was depicted as a dragon 's mouth . the virtuous biblical stories had morphed into crude and sometimes comic stories . the clergy intended to teach against immorality . how ironic , then , that the morality plays actually encouraged vices as more popular than virtues . by the mid-15th century , the church started to outlaw these performances . town charters required that any theater must be built outside the city wall . one of the first theaters was built like a larger version of a pageant , with tiers of gallery seating encircling a grassy area in front of the stage . sound familiar ? a young william shakespeare developed his craft here at the theater that was eventually renamed the globe . the medieval morality play had led to renaissance playwrights who were inspired by the inner struggles and the conscience of man . and that , in essence , is how drama emerged as a literary art form .
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and , at the same time , the opposite virtues of falsehood , covetousness , worldly flesh , and the devil became the antagonists . the morality plays were allegorical stories in which these characters battled for the control of the soul . audiences loved the immoral characters , and spectators were encouraged to interact with the actors .
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if you were to write an allegorical morality play , what would be the names of your characters ?
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what if i told you there were trillions of tiny bacteria all around you ? it 's true . microorganisms called bacteria were some of the first life forms to appear on earth . though they consist of only a single cell , their total biomass is greater than that of all plants and animals combined . and they live virtually everywhere : on the ground , in the water , on your kitchen table , on your skin , even inside you . do n't reach for the panic button just yet . although you have 10 times more bacterial cells inside you than your body has human cells , many of these bacteria are harmless or even beneficial , helping digestion and immunity . but there are a few bad apples that can cause harmful infections , from minor inconveniences to deadly epidemics . fortunately , there are amazing medicines designed to fight bacterial infections . synthesized from chemicals or occurring naturally in things like mold , these antibiotics kill or neutralize bacteria by interrupting cell wall synthesis or interfering with vital processes like protein synthesis , all while leaving human cells unharmed . the deployment of antibiotics over the course of the 20th century has rendered many previously dangerous diseases easily treatable . but today , more and more of our antibiotics are becoming less effective . did something go wrong to make them stop working ? the problem is not with the antibiotics but the bacteria they were made to fight , and the reason lies in darwin 's theory of natural selection . just like any other organisms , individual bacteria can undergo random mutations . many of these mutations are harmful or useless , but every now and then , one comes along that gives its organism an edge in survival . and for a bacterium , a mutation making it resistant to a certain antibiotic gives quite the edge . as the non-resistant bacteria are killed off , which happens especially quickly in antibiotic-rich environments , like hospitals , there is more room and resources for the resistant ones to thrive , passing along only the mutated genes that help them do so . reproduction is n't the only way to do this . some can release their dna upon death to be picked up by other bacteria , while others use a method called conjugation , connecting through pili to share their genes . over time , the resistant genes proliferate , creating entire strains of resistant super bacteria . so how much time do we have before these superbugs take over ? well , in some bacteria , it 's already happened . for instance , some strands of staphylococcus aureus , which causes everything from skin infections to pneumonia and sepsis , have developed into mrsa , becoming resistant to beta-lactam antibiotics , like penicillin , methicillin , and oxacillin . thanks to a gene that replaces the protein beta-lactams normally target and bind to , mrsa can keep making its cell walls unimpeded . other super bacteria , like salmonella , even sometimes produce enzymes like beta-lactams that break down antibiotic attackers before they can do any damage , and e. coli , a diverse group of bacteria that contains strains that cause diarrhea and kidney failure , can prevent the function of antibiotics , like quinolones , by actively booting any invaders that manage to enter the cell . but there is good news . scientists are working to stay one step ahead of the bacteria , and although development of new antibiotics has slowed in recent years , the world health organization has made it a priority to develop novel treatments . other scientists are investigating alternate solutions , such as phage therapy or using vaccines to prevent infections . most importantly , curbing the excessive and unnecessary use of antibiotics , such as for minor infections that can resolve on their own , as well as changing medical practice to prevent hospital infections , can have a major impact by keeping more non-resistant bacteria alive as competition for resistant strains . in the war against super bacteria , deescalation may sometimes work better than an evolutionary arms race .
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well , in some bacteria , it 's already happened . for instance , some strands of staphylococcus aureus , which causes everything from skin infections to pneumonia and sepsis , have developed into mrsa , becoming resistant to beta-lactam antibiotics , like penicillin , methicillin , and oxacillin . thanks to a gene that replaces the protein beta-lactams normally target and bind to , mrsa can keep making its cell walls unimpeded . other super bacteria , like salmonella , even sometimes produce enzymes like beta-lactams that break down antibiotic attackers before they can do any damage , and e. coli , a diverse group of bacteria that contains strains that cause diarrhea and kidney failure , can prevent the function of antibiotics , like quinolones , by actively booting any invaders that manage to enter the cell .
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penicillin-binding protein 2a , encoded by the meda gene , isn ’ t affected by beta-lactam antibiotics .
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imagine you 're at a football game when this obnoxious guy sits next to you . he 's loud , he spills his drink on you , and he makes fun of your team . days later , you 're walking in the park when suddenly it starts to pour rain . who should show up at your side to offer you an umbrella ? the same guy from the football game . do you change your mind about him based on this second encounter , or do you go with your first impression and write him off ? research in social psychology suggests that we 're quick to form lasting impressions of others based on their behaviors . we manage to do this with little effort , inferring stable character traits from a single behavior , like a harsh word or a clumsy step . using our impressions as guides , we can accurately predict how people are going to behave in the future . armed with the knowledge the guy from the football game was a jerk the first time you met him , you might expect more of the same down the road . if so , you might choose to avoid him the next time you see him . that said , we can change our impressions in light of new information . behavioral researchers have identified consistent patterns that seem to guide this process of impression updating . on one hand , learning very negative , highly immoral information about someone typically has a stronger impact than learning very positive , highly moral information . so , unfortunately for our new friend from the football game , his bad behavior at the game might outweigh his good behavior at the park . research suggests that this bias occurs because immoral behaviors are more diagnostic , or revealing , of a person 's true character . okay , so by this logic , bad is always stronger than good when it comes to updating . well , not necessarily . certain types of learning do n't seem to lead to this sort of negativity bias . when learning about another person 's abilities and competencies , for instance , this bias flips . it 's actually the positive information that gets weighted more heavily . let 's go back to that football game . if a player scores a goal , it ultimately has a stronger impact on your impression of their skills than if they miss the net . the two sides of the updating story are ultimately quite consistent . overall , behaviors that are perceived as being less frequent are also the ones that people tend to weigh more heavily when forming and updating impressions , highly immoral actions and highly competent actions . so , what 's happening at the level of the brain when we 're updating our impressions ? using fmri , or functional magnetic resonance imaging , researchers have identified an extended network of brain regions that respond to new information that 's inconsistent with initial impressions . these include areas typically associated with social cognition , attention , and cognitive control . moreover , when updating impressions based on people 's behaviors , activity in the ventrolateral prefrontal cortex and the superior temporal sulcus correlates with perceptions of how frequently those behaviors occur in daily life . in other words , the brain seems to be tracking low-level , statistical properties of behavior in order to make complex decisions regarding other people 's character . it needs to decide is this person 's behavior typical or is it out of the ordinary ? in the situation with the obnoxious-football-fan-turned-good-samaritan , your brain says , `` well , in my experience , pretty much anyone would lend someone their umbrella , but the way this guy acted at the football game , that was unusual . '' and so , you decide to go with your first impression . there 's a good moral in this data : your brain , and by extension you , might care more about the very negative , immoral things another person has done compared to the very positive , moral things , but it 's a direct result of the comparative rarity of those bad behaviors . we 're more used to people being basically good , like taking time to help a stranger in need . in this context , bad might be stronger than good , but only because good is more plentiful . think about the last time you judged someone based on their behavior , especially a time when you really feel like you changed your mind about someone . was the behavior that caused you to update your impression something you 'd expect anyone to do , or was it something totally out of the ordinary ?
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that said , we can change our impressions in light of new information . behavioral researchers have identified consistent patterns that seem to guide this process of impression updating . on one hand , learning very negative , highly immoral information about someone typically has a stronger impact than learning very positive , highly moral information .
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create a brief story or scenario that describes the typical patterns of impression updating , focusing on behavior that illustrates either ability or morality .
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if you know an older left-handed person , chances are they had to learn to write or eat with their right hand . and in many parts of the world , it 's still common practice to force children to use their `` proper '' hand . even the word for right also means correct or good , not just in english , but many other languages , too . but if being left-handed is so wrong , then why does it happen in the first place ? today , about 1/10 of the world 's population are left-handed . archeological evidence shows that it 's been that way for as long as 500,000 years , with about 10 % of human remains showing the associated differences in arm length and bone density , and some ancient tools and artifacts showing evidence of left-hand use . and despite what many may think , handedness is not a choice . it can be predicted even before birth based on the fetus ' position in the womb . so , if handedness is inborn , does that mean it 's genetic ? well , yes and no . identical twins , who have the same genes , can have different dominant hands . in fact , this happens as often as it does with any other sibling pair . but the chances of being right or left-handed are determined by the handedness of your parents in surprisingly consistent ratios . if your father was left-handed but your mother was right-handed , you have a 17 % chance of being born left-handed , while two righties will have a left-handed child only 10 % of the time . handedness seems to be determined by a roll of the dice , but the odds are set by your genes . all of this implies there 's a reason that evolution has produced this small proportion of lefties , and maintained it over the course of millennia . and while there have been several theories attempting to explain why handedness exists in the first place , or why most people are right-handed , a recent mathematical model suggests that the actual ratio reflects a balance between competitive and cooperative pressures on human evolution . the benefits of being left-handed are clearest in activities involving an opponent , like combat or competitive sports . for example , about 50 % of top hitters in baseball have been left-handed . why ? think of it as a surprise advantage . because lefties are a minority to begin with , both right-handed and left-handed competitors will spend most of their time encountering and practicing against righties . so when the two face each other , the left-hander will be better prepared against this right-handed opponent , while the righty will be thrown off . this fighting hypothesis , where an imbalance in the population results in an advantage for left-handed fighters or athletes , is an example of negative frequency-dependent selection . but according to the principles of evolution , groups that have a relative advantage tend to grow until that advantage disappears . if people were only fighting and competing throughout human evolution , natural selection would lead to more lefties being the ones that made it until there were so many of them , that it was no longer a rare asset . so in a purely competitive world , 50 % of the population would be left-handed . but human evolution has been shaped by cooperation , as well as competition . and cooperative pressure pushes handedness distribution in the opposite direction . in golf , where performance does n't depend on the opponent , only 4 % of top players are left-handed , an example of the wider phenomenon of tool sharing . just as young potential golfers can more easily find a set of right-handed clubs , many of the important instruments that have shaped society were designed for the right-handed majority . because lefties are worse at using these tools , and suffer from higher accident rates , they would be less successful in a purely cooperative world , eventually disappearing from the population . so by correctly predicting the distribution of left-handed people in the general population , as well as matching data from various sports , the model indicates that the persistence of lefties as a small but stable minority reflects an equilibrium that comes from competitive and cooperative effects playing out simultaneously over time . and the most intriguing thing is what the numbers can tell us about various populations . from the skewed distribution of pawedness in cooperative animals , to the slightly larger percentage of lefties in competitive hunter-gatherer societies , we may even find that the answers to some puzzles of early human evolution are already in our hands .
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but the chances of being right or left-handed are determined by the handedness of your parents in surprisingly consistent ratios . if your father was left-handed but your mother was right-handed , you have a 17 % chance of being born left-handed , while two righties will have a left-handed child only 10 % of the time . handedness seems to be determined by a roll of the dice , but the odds are set by your genes .
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what are some ways archaeologists can tell if someone was left-handed ?
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when we think of classic works of art , the most common setting we imagine them in is a museum . but what we often forget is that much of this art was not produced with a museum setting in mind . what happens to an artwork when it 's taken out of its originally intended context ? take the example of michelangelo 's statue of david , depicting the boy hero who slew the giant philistine , goliath , armed with only his courage and his slingshot . when michelangelo began carving a block of pure white marble to communicate this famous biblical story , the city of florence intended to place the finished product atop their grand cathedral . not only would the 17 foot tall statue be easily visible at this height , but its placement alongside 11 other statues of old testament heroes towering over onlookers would have a powerful religious significance , forcing the viewer to stare in awe towards the heavens . but by the time michelangelo had finished the work , in 1504 , the plans for the other statues had fallen through , and the city realized that lifting such a large sculpture to the roof would be more difficult than they had thought . furthermore , the statue was so detailed and lifelike , down to the bulging veins in david 's arm and the determination on his face , that it seemed a shame to hide it so far from the viewer . a council of politicians and artists convened to decide on a new location for the statue . ultimately voting to place it in front of the palazzo della signoria , the town hall and home of the new republican government . this new location transformed the statue 's meaning . the medici family , who for generations had ruled the city through their control of banking , had recently been exiled , and florence now saw itself as a free city , threatened on all sides by wealthy and powerful rivals . david , now the symbol of heroic resistance against overwhelming odds , was placed with his intense stare , now a look of stern warning , focused directly towards rome , the home of cardinal giovanni de medici . though the statue itself had not been altered , its placement changed nearly every aspect of it from a religious to a political significance . though a replica of david still appears at the palazzo , the original statue was moved in 1873 to the galleria dell'accademia , where it remains today . in the orderly , quiet environment of the museum , alongside numerous half-finished michelangelo sculptures , overt religious and political interpretations fall away , giving way to detached contemplation of michelangelo 's artistic and technical skill . but even here , the astute viewer may notice that david 's head and hand appear disproportionately large , a reminder that they were made to be viewed from below . so , not only does context change the meaning and interpretation of an artwork throughout its history , sometimes it can make that history resurface in the most unexpected ways .
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what happens to an artwork when it 's taken out of its originally intended context ? take the example of michelangelo 's statue of david , depicting the boy hero who slew the giant philistine , goliath , armed with only his courage and his slingshot . when michelangelo began carving a block of pure white marble to communicate this famous biblical story , the city of florence intended to place the finished product atop their grand cathedral .
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towards which city does michelangelo ’ s statue of david face ?
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why does your mouth feel like it 's on fire when you eat a spicy pepper ? and how do you soothe the burn ? why does wasabi make your eyes water ? and how spicy is the spiciest spice ? let 's back up a bit . first , what is spiciness ? even though we often say that something tastes spicy , it 's not actually a taste , like sweet or salty or sour . instead , what 's really happening is that certain compounds in spicy foods activate the type of sensory neurons called polymodal nociceptors . you have these all over your body , including your mouth and nose , and they 're the same receptors that are activated by extreme heat . so , when you eat a chili pepper , your mouth feels like it 's burning because your brain actually thinks it 's burning . the opposite happens when you eat something with menthol in it . the cool , minty compound is activating your cold receptors . when these heat-sensitive receptors are activated , your body thinks it 's in contact with a dangerous heat source and reacts accordingly . this is why you start to sweat , and your heart starts beating faster . the peppers have elicited the same fight-or-flight response with which your body reacts to most threats . but you may have noticed that not all spicy foods are spicy in the same way . and the difference lies in the types of compounds involved . the capsaicin and piperine , found in black pepper and chili peppers , are made up of larger , heavier molecules called alkylamides , and those mostly stay in your mouth . mustard , horseradish , and wasabi are made up of smaller molecules , called isothiocyanates , that easily float up into your sinuses . this is why chili peppers burn your mouth , and wasabi burns your nose . the standard measure of a food 's spiciness is its rating on the scoville scale , which measures how much its capsaicin content can be diluted before the heat is no longer detectable to humans . a sweet bell pepper gets 0 scoville heat units , while tabasco sauce clocks in between 1,200-2,400 units . the race to create the hottest pepper is a constant battle , but two peppers generally come out on top : the trinidad moruga scorpion and the carolina reaper . these peppers measure between 1.5 and 2 million scoville heat units , which is about half the units found in pepper spray . so , why would anyone want to eat something that causes such high levels of pain ? nobody really knows when or why humans started eating hot peppers . archaeologists have found spices like mustard along with human artifacts dating as far back as 23,000 years ago . but they do n't know whether the spices were used for food or medication or just decoration . more recently , a 6,000 year old crockpot , lined with charred fish and meat , also contained mustard . one theory says that humans starting adding spices to food to kill off bacteria . and some studies show that spice developed mostly in warmer climates where microbes also happen to be more prevalent . but why we continue to subject ourselves to spicy food today is still a bit of a mystery . for some people , eating spicy food is like riding rollercoasters ; they enjoy the ensuing thrill , even if the immediate sensation is unpleasant . some studies have even shown that those who like to eat hot stuff are more likely to enjoy other adrenaline-rich activities , like gambling . the taste for spicy food may even be genetic . and if you 're thinking about training a bit , to up your tolerance for spice , know this : according to some studies , the pain does n't get any better . you just get tougher . in fact , researchers have found that people who like to eat spicy foods do n't rate the burn any less painful than those who do n't . they just seem to like the pain more . so , torment your heat receptors all you want , but remember , when it comes to spicy food , you 're going to get burned .
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so , why would anyone want to eat something that causes such high levels of pain ? nobody really knows when or why humans started eating hot peppers . archaeologists have found spices like mustard along with human artifacts dating as far back as 23,000 years ago .
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what does your brain think when you ’ re eating a hot pepper ?
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meet our chemist , harriet . she has a chemical reaction that needs to occur more quickly . a chemist has some processes at her disposal that can help her speed up her reaction , and she knows of five ways . and to remember them , she thinks back to her days as a high school student , and the day she got a date for the dance . harriet was in high school , studying between classes . she had lost track of time and was going to be late to class . unbeknownst to her , harold , who was just around the corner , was running late , too . they both sprinted to class and , as it happened , sprinted directly into one another . now , this was no small collision . they ran squarely into one another in such a way that he knocked the books right out of her hand . `` i 'm sorry , '' he said . `` let me help you with your books . '' he kindly helped her re-collect her belongings , and politely offered to walk her to class . and you 'll never guess who went together to the dance later that year . yup , those two . so as we can see from this example , the key to getting a date for the dance is to collide with someone and knock the books out of their hands . now , you 're probably already aware that not all collisions lead to dates for the dance , thankfully . the collisions must have two important characteristics : one , correct orientation that allows books to be knocked from one 's hands ; and two , enough energy to knock the books out . shortly after this incident , harriet decided to tell me , her chemistry teacher , all about it . i noticed some interesting parallels between her story and chemical reaction rates , which happened to be what she was studying in the hallway the day of the collision . together , we decided to set out on two missions . harriet wanted to help all chemistry students and chemists remember how to speed up the rate of chemical reactions and i , being the nice guy that i am , decided to make it my mission to help create educational environments in which more book-dropping collisions can take place to increase future chemists ' chances of getting a date for the dance . in order to facilitate this improved dance-date-getting process , i propose five changes to all schools that parallel harriet 's five ways to increase chemical reaction rates . first , i propose that we shrink the size of the hallways . this will make it more difficult to safely navigate the hallways and will cause more collisions than in larger hallways . and by increasing the number of collisions , we increase the likelihood that some of those collisions will have the correct alignment and enough energy to create a date to the dance . now , chemically speaking , this is equivalent to lowering the volume of a reaction vessel or a reaction mixture . in doing so , the individual particles are closer together , and more collisions will occur . more collisions means a greater likelihood that collisions with the appropriate energy and configuration will happen . second , i propose increasing the overall population of the school . more students equals more collisions . by increasing the number of particles available for collision , we create an environment where more collisions can take place . third , we must reduce the time allowed between classes -- heck , let 's just cut it in half . in doing so , students will need to move more quickly to get from one class to the next . this increase in velocity will help make sure collisions have the appropriate amount of energy necessary to ensure book-dropping . this is analogous to increasing the temperature of the reaction mixture . higher temperature means particles are moving faster . faster-moving particles means more energy , and a greater likelihood of the reaction-causing collision . fourth , students must stop traveling in packs . by traveling in packs , the students on the outside of the pack insulate those in the middle from undergoing any collisions . by splitting up , each student has more area exposed that is available for a collision from a passing student . when particles travel in packs , the surface area is very small , and only the outside particles can collide . however , by breaking up the clumps into individual particles , the total surface area is increased , and each particle has an exposed surface that can react . fifth and finally , we hire a matchmaker . is this colliding and book-dropping too violent ? is there an easier way to get a date that requires less initial energy ? then a matchmaker will help with this . the matchmaker makes it easier for a couple to get together , by coordinating the match . our matchmaker is like a catalyst . chemical catalysts function by lowering the activation energy -- in other words , by lowering the energy required to start a reaction . they do this by bringing two particles together and orienting them correctly in space so that the two can meet at the correct configuration and allow a reaction to take place . so , to sum up : if a future chemist wants a date for the dance , he must collide with another person and knock the books out of their hands . and if a chemist wants to make a chemical reaction occur , the particles must collide in the correct orientation with an appropriate amount of energy . and both of these processes can be accelerated , using the five methods i 've described .
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meet our chemist , harriet . she has a chemical reaction that needs to occur more quickly . a chemist has some processes at her disposal that can help her speed up her reaction , and she knows of five ways .
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in what ways is being able to control the rate of a chemical reaction useful to the following chemistry-rich professions : chemical engineer , physician , chef ?
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our story is about a girl named iris . iris is very sensitive . ( bird cawing ) so much that she is always in tears . she cries when she 's sad , when she 's happy , ( godzilla roars ) and even tears up when things just get to her . she has special lacrimal glands to make new tears and special tubes , called lacrimal puncta , to drain old ones away . and she cries so much that she goes through ten ounces of tears per day , thirty gallons a year ! in fact , if you look closely , you 'll see that she 's crying a little bit all the time . the basal tears that iris constantly produces form a thin coating of three layers that cover her and keep dirt and debris away . right next to iris is the mucus layer , which keeps the whole thing fastened to her . on top of it is the aqueous layer , which keeps iris hydrated , repels invasive bacteria , and protects her skin , or cornea , from damage . and , finally , there is the lipid layer , an oily outer film that keeps the surface smooth for iris to see through , and prevents the other layers from evaporating . normally , iris goes about her day without really noticing the basal tears doing their thing . that 's kind of their whole point . but one day , she meets a girl named onion . iris is immediately smitten . onion looks gorgeous in her bright purple jacket , and she smells terrific . so , iris invites onion to her house for dinner . but when she comes in and takes off her jacket , something terrible happens . you see , when onion 's jacket is removed , a chemical reaction happens , converting the sulfoxides that make her smell so great into sulfenic acid , which then becomes a nasty substance with a long name : syn-propanethial s-oxide . the gas stings iris , and suddenly , she ca n't help it , she starts weeping uncontrollably . these reflex tears are different from the basal tears that iris is used to . because they 're designed to wash away harmful substances , or particles , they 're released in much larger amounts , and their aqueous layer contains more antibodies to stop any microorganisms that may be trying to get in , as well . both iris and onion are devastated . they know they ca n't continue their relationship if iris is going to hurt and cry every time onion takes off her jacket . so , they decide to break up . as onion walks out the door , iris stops crying . and immediately starts again . only now , she 's not crying reflex tears but emotional tears . when someone is either too sad or too happy , it feels like a loss of control , which can be dangerous . so , emotional tears are sent in to stabilize the mood as quickly as possible , along with other physical reactions , such as an increased heart rate and slower breathing . but scientists still are n't sure exactly how or why the tears themselves are helpful . they may be a social mechanism to elicit sympathy or show submission . but some studies have also found that emotional tears contain higher levels of stress hormones , such as acth and enkephalin , an endorphin and natural pain killer . in this case , emotional tears are also directly calming iris down , as well as signaling her emotional state to others . sorry things did n't work out with onion , iris , but do n't worry . as long as you have all three kinds of tears working to keep you balanced and healthy , it will get better . you 'll see .
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and immediately starts again . only now , she 's not crying reflex tears but emotional tears . when someone is either too sad or too happy , it feels like a loss of control , which can be dangerous .
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reflex tears do all of the following except :
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`` hey , another atom . i 'm hydrogen , nice to meet you . how are you feeling about the jump ? '' `` hi there , i 'm antihydrogen , your antiatom , and to be honest , i 'm feeling kind of neutral . my positron and antiproton balance out , just like your electron and proton , right ? '' `` hey , yeah ! you look just like me , but different somehow . '' `` whoa , be careful ! if we get too close , we 'll disappear in a spark of energy . i 'd like to stay in one piece . '' `` oh wow , sorry . '' `` it 's okay . i was just thinking , it 's kind of weird for us to be chatting like this before our jump above cern . '' `` why 's that ? '' `` well , for starters , how do we know we 'll both fall ? '' `` of course we 'll fall . it 's gravity , you know , the force of attraction between masses . i even know how fast we should fall . galileo showed in that tower experiment that all falling objects accelerate at the same rate , regardless of mass . '' `` that 's for bigger objects . it 's a different story for small particles like us . our mass is so tiny that the gravitational force we experience is miniscule , and if the particles are charged , like my antiproton or your proton , then it becomes impossible to detect compared to the much greater electromagnetic force acting on them . '' `` but that 's only for charged particles . you and i are both neutral . our charges balance out , so the electromagnetic force is small and the gravitational force should be detectable . i know mine 's been measured . '' `` because you 're everywhere , but i 'm kind of hard to find . '' `` why is that , anyway ? should n't there have been an equal amount of matter and antimatter created in the big bang ? '' `` you 'd think so , but then all of those particles would have annihilated each other into energy , remember ? and the universe is obviously full of matter . no one knows why there is more matter than antimatter , which is why scientists are so interested in studying me . '' `` so where do they find you anyway ? '' `` actually , i was made in that lab down there . they needed an accelerator to make my antiproton because it 's so heavy , just as heavy as your proton . getting my positron was easier . it 's much lighter , like your electron , and there are materials that naturally decay by emitting one . then they just had to put the two together and they got me . but it 's only recently that they 've been able to keep me around long enough to study my properties . '' `` and now they 've sent you on this jump with me . hey , wait a minute . '' `` that 's right . we 're reenacting galileo 's experiment , but with matter and antimatter instead of two objects made of matter . '' `` so what 's going to happen ? are you going to fall upwards or something ? '' `` only one way to find out ! ''
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`` that 's right . we 're reenacting galileo 's experiment , but with matter and antimatter instead of two objects made of matter . '' `` so what 's going to happen ?
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what happens if a matter particle meets its antimatter counterpart ?
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three and a half thousand years ago in egypt , a noble pharaoh was the victim of a violent attack . but the attack was not physical . this royal had been dead for 20 years . the attack was historical , an act of damnatio memoriae , the damnation of memory . somebody smashed the pharaoh 's statues , took a chisel and attempted to erase the pharaoh 's name and image from history . who was this pharaoh , and what was behind the attack ? here 's the key : the pharaoh hatshepsut was a woman . in the normal course of things , she should never have been pharaoh . although it was legal for a woman to be a monarch , it disturbed some essential egyptian beliefs . firstly , the pharaoh was known as the living embodiment of the male god horus . secondly , disturbance to the tradition of rule by men was a serious challenge to maat , a word for `` truth , '' expressing a belief in order and justice , vital to the egyptians . hatshepsut had perhaps tried to adapt to this belief in the link between order and patriarchy through her titles . she took the name maatkare , and sometimes referred to herself as hatshepsu , with a masculine word ending . but apparently , these efforts did n't convince everyone , and perhaps someone erased hatshepsut 's image so that the world would forget the disturbance to maat , and egypt could be balanced again . hatshepsut , moreover , was not the legitimate heir to the thrown , but a regent , a kind of stand-in co-monarch . the egyptian kingship traditionally passed from father to son . it passed from thutmose i to his son thutmose ii , hatshepsut 's husband . it should have passed from thutmose ii directly to his son thutmose iii , but thutmose iii was a little boy when his father died . hatshepsut , the dead pharaoh 's chief wife and widow , stepped in to help as her stepson 's regent but ended up ruling beside him as a fully fledged pharaoh . perhaps thutmose iii was angry about this . perhaps he was the one who erased her images . it 's also possible that someone wanted to dishonor hatshepsut because she was a bad pharaoh . but the evidence suggests she was actually pretty good . she competently fulfilled the traditional roles of the office . she was a great builder . her mortuary temple , djeser-djeseru , was an architectural phenomenon at the time and is still admired today . she enhanced the economy of egypt , conducting a very successful trade mission to the distant land of punt . she had strong religious connections . she even claimed to be the daughter of the state god , amun . and she had a successful military career , with a nubian campaign , and claims she fought alongside her soldiers in battle . of course , we have to be careful when we assess the success of hatshepsut 's career , since most of the evidence was written by hatshepsut herself . she tells her own story in pictures and writing on the walls of her mortuary temple and the red chapel she built for amun . so who committed the crimes against hatshepsut 's memory ? the most popular suspect is her stepson , nephew and co-ruler , thutmose iii . did he do it out of anger because she stole his throne ? this is unlikely since the damage was n't done until 20 years after hatshepsut died . that 's a long time to hang onto anger and then act in a rage . maybe thutmose iii did it to make his own reign look stronger . but it is most likely that he or someone else erased the images so that people would forget that a woman ever sat on egypt 's throne . this gender anomaly was simply too much of a threat to maat and had to be obliterated from history . happily , the ancient censors were not quite thorough enough . enough evidence survived for us to piece together what happened , so the story of this unique powerful woman can now be told .
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who was this pharaoh , and what was behind the attack ? here 's the key : the pharaoh hatshepsut was a woman . in the normal course of things , she should never have been pharaoh .
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why was it unusual that hatshepsut became pharaoh ?
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how do you know you 're real ? it 's an obvious question until you try to answer it , but let 's take it seriously . how do you really know you exist ? in his `` meditations on first philosophy , '' rené descartes tried to answer that very question , demolishing all his preconceived notions and opinions to begin again from the foundations . all his knowledge had come from his sensory perceptions of the world . same as you , right ? you know you 're watching this video with your eyes , hearing it with your ears . your senses show you the world as it is . they are n't deceiving you , but sometimes they do . you might mistake a person far away for someone else , or you 're sure you 're about to catch a flyball , and it hits the ground in front of you . but come on , right here and now , you know what 's right in front of you is real . your eyes , your hands , your body : that 's you . only crazy people would deny that , and you know you 're not crazy . anyone who 'd doubt that must be dreaming . oh no , what if you 're dreaming ? dreams feel real . you can believe you 're swimming , flying or fighting off monsters with your bare hands , when your real body is lying in bed . no , no , no . when you 're awake , you know you 're awake . ah ! but when you are n't , you do n't know you are n't , so you ca n't prove you are n't dreaming . maybe the body you perceive yourself to have is n't really there . maybe all of reality , even its abstract concepts , like time , shape , color and number are false , all just deceptions concocted by an evil genius ! no , seriously . descartes asks if you can disprove the idea that an evil genius demon has tricked you into believing reality is real . perhaps this diabolical deceiver has duped you . the world , your perceptions of it , your very body . you ca n't disprove that they 're all just made up , and how could you exist without them ? you could n't ! so , you do n't . life is but a dream , and i bet you are n't row , row , rowing the boat merrily at all , are you ? no , you 're rowing it wearily like the duped , nonexistent doof you are/are n't . do you find that convincing ? are you persuaded ? if you are n't , good ; if you are , even better , because by being persuaded , you would prove that you 're a persuaded being . you ca n't be nothing if you think you 're something , even if you think that something is nothing because no matter what you think , you 're a thinking thing , or as descartes put it , `` i think , therefore i am , '' and so are you , really . ( airplane engine )
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how do you know you 're real ? it 's an obvious question until you try to answer it , but let 's take it seriously . how do you really know you exist ?
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how did descartes try to answer the question about existence ?
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translator : andrea mcdonough reviewer : bedirhan cinar hello , my name is christian rudder , and i was one of the founders of okcupid . it 's now one of the biggest dating sites in the united states . like most everyone at the site , i was a math major , as you may expect , we 're known for the analytic approach we take to love . we call it our matching algorithm . basically , okcupid 's matching algorithm helps us decide whether two people should go on a date . we built our entire business around it . now , algorithm is a fancy word , and people like to drop it like it 's this big thing . but really , an algorithm is just a systematic , step-by-step way to solve a problem . it does n't have to be fancy at all . here in this lesson , i 'm going to explain how we arrived at our particular algorithm , so you can see how it 's done . now , why are algorithms even important ? why does this lesson even exist ? well , notice one very significant phrase i used above : they are a step-by-step way to solve a problem , and as you probably know , computers excel at step-by-step processes . a computer without an algorithm is basically an expensive paperweight . and since computers are such a pervasive part of everyday life , algorithms are everywhere . the math behind okcupid 's matching algorithm is surprisingly simple . it 's just some addition , multiplication , a little bit of square roots . the tricky part in designing it was figuring out how to take something mysterious , human attraction , and break it into components that a computer can work with . the first thing we needed to match people up was data , something for the algorithm to work with . the best way to get data quickly from people is to just ask for it . so we decided that okcupid should ask users questions , stuff like , `` do you want to have kids one day ? '' `` how often do you brush your teeth ? '' `` do you like scary movies ? '' and big stuff like , `` do you believe in god ? '' now , a lot of the questions are good for matching like with like , that is , when both people answer the same way . for example , two people who are both into scary movies are probably a better match than one person who is and one who is n't . but what about a question like , `` do you like to be the center of attention ? '' if both people in a relationship are saying yes to this , they 're going to have massive problems . we realized this early on , and so we decided we needed a bit more data from each question . we had to ask people to specify not only their own answer , but the answer they wanted from someone else . that worked really well . but we needed one more dimension . some questions tell you more about a person than others . for example , a question about politics , something like , `` which is worse : book burning or flag burning ? '' might reveal more about someone than their taste in movies . and it does n't make sense to weigh all things equally , so we added one final data point . for everything that okcupid asks you , you have a chance to tell us the role it plays in your life . and this ranges from irrelevant to mandatory . so now , for every question , we have three things for our algorithm : first , your answer ; second , how you want someone else -- your potential match -- to answer ; and third , how important the question is to you at all . with all this information , okcupid can figure out how well two people will get along . the algorithm crunches the numbers and gives us a result . as a practical example , let 's look at how we 'd match you with another person . let 's call him `` b . '' your match percentage with b is based on questions you 've both answered . let 's call that set of common questions `` s. '' as a very simple example , we use a small set `` s '' with just two questions in common , and compute a match from that . here are our two example questions . the first one , let 's say , is , `` how messy are you ? '' and the answer possibilities are : very messy , average and very organized . and let 's say you answered `` very organized , '' and you 'd like someone else to answer `` very organized , '' and the question is very important to you . basically , you 're a neat freak . you 're neat , you want someone else to be neat , and that 's it . and let 's say b is a little bit different . he answered `` very organized '' for himself , but `` average '' is ok with him as an answer from someone else , and the question is only a little important to him . let 's look at the second question , from our previous example : `` do you like to be the center of attention ? '' the answers are `` yes '' and `` no . '' you 've answered `` no , '' you want someone else to answer `` no , '' and the question is only a little important to you . now b , he 's answered `` yes . '' he wants someone else to answer `` no , '' because he wants the spotlight on him , and the question is somewhat important to him . so , let 's try to compute all of this . our first step is , since we use computers to do this , we need to assign numerical values to ideas like `` somewhat important '' and `` very important , '' because computers need everything in numbers . we at okcupid decided on the following scale : `` irrelevant '' is worth 0 . `` a little important '' is worth 1 . `` somewhat important '' is worth 10 . `` very important '' is 50 . and `` absolutely mandatory '' is 250 . next , the algorithm makes two simple calculations . the first is : how much did b 's answers satisfy you ? that is , how many possible points did b score on your scale ? well , you indicated that b 's answer to the first question , about messiness , was very important to you . it 's worth 50 points and b got that right . the second question is worth only 1 , because you said it was only a little important . b got that wrong , so b 's answers were 50 out of 51 possible points . that 's 98 % satisfactory . pretty good . the second question the algorithm looks at is : how much did you satisfy b ? well , b placed 1 point on your answer to the messiness question and 10 on your answer to the second . of those 11 , that 's 1 plus 10 , you earned 10 -- you guys satisfied each other on the second question . so your answers were 10 out of 11 equals 91 percent satisfactory to b . that 's not bad . the final step is to take these two match percentages and get one number for the both of you . to do this , the algorithm multiplies your scores , then takes the nth root , where `` n '' is the number of questions . because s , which is the number of questions in this sample , is only 2 , we have : match percentage equals the square root of 98 percent times 91 percent . that equals 94 percent . that 94 percent is your match percentage with b . it 's a mathematical expression of how happy you 'd be with each other , based on what we know . now , why does the algorithm multiply , as opposed to , say , average the two match scores together , and do the square-root business ? in general , this formula is called the geometric mean . it 's a great way to combine values that have wide ranges and represent very different properties . in other words , it 's perfect for romantic matching . you 've got wide ranges and you 've got tons of different data points , like i said , about movies , politics , religion -- everything . intuitively , too , this makes sense . two people satisfying each other 50 percent should be a better match than two others who satisfy 0 and 100 , because affection needs to be mutual . after adding a little correction for margin of error , in the case where we have a small number of questions , like we do in this example , we 're good to go . any time okcupid matches two people , it goes through the steps we just outlined . first it collects data about your answers , then it compares your choices and preferences to other people 's in simple , mathematical ways . this , the ability to take real-world phenomena and make them something a microchip can understand , is , i think , the most important skill anyone can have these days . like you use sentences to tell a story to a person , you use algorithms to tell a story to a computer . if you learn the language , you can go out and tell your stories . i hope this will help you do that .
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here in this lesson , i 'm going to explain how we arrived at our particular algorithm , so you can see how it 's done . now , why are algorithms even important ? why does this lesson even exist ?
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what other applications for algorithms do you think could be applied to a social group ? okcupid tackled dating -- what else is there ?
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every day we are bombarded on all platforms of media with personal stories that span the continuum from the embarrassing and the trivial to the dire and the critical . the foodie posting photos of every plate of lasagna he orders , the iranian blogger describing the shooting death of nedā āghā-soltān . authentic narrative is the glue that connects people , providing a compelling reason to keep reading . it makes the personal universal , transcends the individual , and makes a story timeless and humanistic . how , as a journalist , do you ask the questions that yield this type of narrative ? you have to know what to ask of whom . first you need to understand that every piece of journalism requires a trifecta of sourcing . if you picture the reporting process as depicted by a triangle , one side will be official sources , another side will be overview sources , and a third side will be unofficial sources . all three components are necessary in every well-reported piece . the first side has official sources . those are the people with titles and expertise , who own the company ; are spokespeople for the movement . they tell you the numbers , and the answers to how much , how many , where , when , and who . a second side of the triangle includes overview sources : academics , consultants , authors , who are not directly connected as stakeholders , but have knowledge of the big picture . yet it is the third side of the trifecta - unofficial sources - who hold the power of the individual 's insight . this is where you can find the why , giving consequence on the event , trend , phase , or idea and what it means on a soul level to someone affected by it . so how do you mine for the gems , identifying what is compelling from what is chatter ? you ask surprising questions . to achieve the complicated , fragile human connection , you regard the stories of every subject as sacred . realize that an anecdote is oxygen that breathes life into a grey story of exposition , facts and data . what the surgeon did at home the morning he operated on a woman 's brain tumor . how it feels to dream and train for the olympics for a lifetime . there are times when it is important to convey information quickly , to present bulleted facts and updates . when a situation is urgent , when action is required now , when you need to know where the tornado will hit , how fast the fire is spreading , and if it will reach your home today . but the narrative personal stories that contribute to the buffet of journalism are pieces that have the luxury of a slow dance of information . it is this artful solicitation of story that will make the journalism memorable and will deliver the narrative bond that will connect us to each other .
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how it feels to dream and train for the olympics for a lifetime . there are times when it is important to convey information quickly , to present bulleted facts and updates . when a situation is urgent , when action is required now , when you need to know where the tornado will hit , how fast the fire is spreading , and if it will reach your home today .
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an unofficial source in a story provides what kind of information ?
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for most jobs , it 's understood that you can be fired , whether for crime , incompetence , or just poor performance . but what if your job happens to be the most powerful position in the country , or the world ? that 's where impeachment comes in . impeachment is n't the same as actually removing someone from office . like an indictment in criminal court , it 's only the formal accusation that launches a trial , which could end in conviction or acquittal . originating in the united kingdom , impeachment allowed parliament to vote for removing a government official from office even without the king 's consent . although this was an important check on royal power , the king could n't be impeached because the monarch was considered the source of all government power . but for the founders of the american republic , there was no higher authority beyond the people themselves . and so impeachment was adopted in the united states as a power of congress applying to any civil officers , up to and including the president . although demands for impeachment can come from any members of the public , only the house of representatives has the power to actually initiate the process . it begins by referring the matter to a committee , usually the house committee on rules and the house committee on the judiciary . these committees review the accusations , examine the evidence , and issue a recommendation . if they find sufficient grounds to proceed , the house holds a separate vote on each of the specific charges , known as articles of impeachment . if one or more passes by a simple majority , the official is impeached and the stage is set for trial . the actual trial that follows impeachment is held in the senate . selected members of the house , known as managers , act as the prosecution , while the impeached official and their lawyers present their defense . the senate acts as both judge and jury , conducting the trial and deliberating after hearing all the arguments . if it 's the president or vice president being impeached , the chief justice of the supreme court presides . a conviction requires a supermajority of two-thirds and results in automatic removal from power . depending on the original charges , it can also disqualify them from holding office in the future and open them to standard criminal prosecution . so what exactly can get someone impeached ? that 's a bit more complicated . unlike in the united kingdom , impeachment in the u.s. pits an elected legislature against other democratically elected members of government . therefore , to prevent the process from being used as a political weapon , the constitution specifies that an official can only be impeached for treason , bribery , or other high crimes and misdemeanors . that still leaves a lot of room for interpretation , not to mention politics , and many impeachment trials have split along partisan lines . but the process is generally understood to be reserved for serious abuses of power . the first official to be impeached was tennesse senator william blount in 1797 for conspiring with britain to cease the spanish colony of louisiana . since then , the house has launched impeachment investigations about 60 times , but only 19 have led to actual impeachment proceedings . the eight cases that ended in a conviction and removal from office were all federal judges . and impeachment of a sitting president is even more rare . andrew johnson was impeached in 1868 for attempting to replace secretary of war edwin stanton without consulting the senate . over a century later , bill clinton was impeached for making false statements under oath during a sexual harassment trial . both were ultimately acquitted when the senate 's votes to convict fell short of the required two-thirds majority . and contrary to popular belief , richard nixon was never actually impeached for the watergate scandal . he resigned before it could happen knowing he would almost certainly be convicted . theoretically , the u.s. government is already designed to prevent abuses of power , limiting different branches through a system of checks and balances , term limits , and free elections . but impeachment can be seen as an emergency brake for when these safeguards fail .
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the first official to be impeached was tennesse senator william blount in 1797 for conspiring with britain to cease the spanish colony of louisiana . since then , the house has launched impeachment investigations about 60 times , but only 19 have led to actual impeachment proceedings . the eight cases that ended in a conviction and removal from office were all federal judges .
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what does impeachment mean ?
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so , you 're thinking of moving to mars . have you picked out a spot for your new home ? no ? well , i 'm here to help . first things first , here are some of the things you 'll need to bring to the red planet : a high tolerance for cold , loneliness , and radiation ; a lifetime supply of breathable air and food ; a multibillion dollar spaceship ; a desire to just get away from it all ; and water . you 're definitely going to need water . so what sort of real estate are you looking for ? how about a mansion in the maze-like noctis labyrinthus ? a hideaway in the happy face crater ? a fortress on the face mesa ? an oceanview ? uh , bad news on the last one . you 're about 4 billion years late . we 're pretty sure that mars used to have oceans , lakes , rivers , the whole package . but over time , almost all of it froze beneath the surface , or evaporated off into space . there 's probably still some trapped beneath the seasonally expanding and contracting carbon dioxide ice caps , though . so what might mars look like today if it had surface water ? that , of course , depends on how much we 're talking about , but maybe something like this . the relatively flat northern hemisphere is below the average elevation , so it would become one giant ocean , while the crater-ridden southern hemisphere would stay mostly high and dry . that difference between hemispheres is a bit bizarre , and we do n't know why it 's like that . the southern half is probably much older , judging by features like the number of craters , and the evidence of increased volcanic activity in the north . okay , so who knows ? maybe one day mars will have oceans again , but for now , what we 've got is essentially one giant dusty desert . in fact , it 's similar enough to deserts on earth , that we 've been able to learn a great deal about mars on our home planet . for instance , martian sand dunes form and behave similarly to our sand dunes , though the martian versions often grow twice as large thanks to a gravitational pull that 's about a third as strong as ours . and mars has some features you wo n't see on earth , like tars , which are crestless sand dunes up to fifteen meters tall , whose formations we have yet to understand . you 're probably wondering , `` what do you get when you combine a planet-wide desert with an atmosphere that , like ours , is subject to wind-generating pressure differentials , dust storms ? '' these will be your main weather hazards on the red planet . they play a large part in making the planet red by distributing rusted iron particles across the surface and into the air . thanks to the low gravity and lack of moisture , these dust storms can last for months and cover the planet . so , you might want to build your home as high as possible . well , look no further . this is olympus mons , the largest volcano in the solar system . even if mars had a breathable atmosphere , you 'd find the views from the 25 kilometer summit breathtaking . or are volcanos not your thing ? then how about valles marineris , the largest canyon in the solar system ? it 's so wide that from one side , the opposite rim would be below the curve of the horizon . still , you 'll catch some spectacular blue sunsets in the normally red sky , which gets its color from the dust absorbing most of the blue light , and the way sunlight is scattered by the atmosphere . have you got spirit , curiosity , or are you just looking for opportunity ? then stop stalling and make the move to mars today . mars : redder than ever .
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there 's probably still some trapped beneath the seasonally expanding and contracting carbon dioxide ice caps , though . so what might mars look like today if it had surface water ? that , of course , depends on how much we 're talking about , but maybe something like this .
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we consider water fundamental to life , so scientists think that searching for evidence of water on mars can bring us closer to finding evidence of life there . but could other elements be more fundamental to life on mars ? could it be possible that we are totally wrong in our expectations about life on other planets ? what other things do you think we should consider in our future investigations ?
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why do humans drink so much milk ? and given that all mammals lactate , why do we favor certain types of milk over others ? milk is the first thing we drink , and thanks to developments in the production and variety of dairy products , it can take on countless forms for our dietary and sensory well-being . milk 's primary function is as a complete source of nutrition for newborns . in fact , since it has all of the vital nutrients for development and growth , proteins , carbohydrates , fats , vitamins and minerals , and water , milk is the only thing a baby even needs to ingest for the first six months of life . the unique makeup of milk can vary depending on factors like species , diet , and location . reindeer of the arctic circle , for example , make energy-dense milk that 's about 20 % fat , roughly five times more than human or cow 's milk , to help their young survive the harsh , freezing climate . so how is milk made ? in the uniquely mammalian process of lactation , a special class of milk-secreting cells known as mammocytes line up in a single layer around pear-shaped alveoli . those cells absorb all of the building blocks of milk , then synthesize tiny droplets of fat on structures called smooth endoplasmic reticula . the droplets combine with each other and other molecules and are then expelled and stored in spaces between cells . mammary glands eventually secrete the milk through the breasts , udders , or , in the rare case of the platypus , through ducts in the abdomen . although this process is typically reserved for females , in some species , like dayak fruit bats , goats , and even cats , males can also lactate . milk drinkers worldwide consume dairy from buffalo , goats , sheeps , camels , yaks , horses , and cows . almost all of these species are ruminants , a type of mammal with four-chambered stomachs that yield large quantities of milk . of these , cows were the most easily domesticated and produce a milk that is both easily separated into cream and liquid and has a similar fat content to human milk . in their natural environment , mammals secrete milk on call for immediate consumption by their young . but with the demands of thirsty consumers , the dairy industry has enlisted methods to step up production , enhance shelf life , and provide a variety of milk products . in the dairy , centrifugation machines spin milk at high speeds , forcing less dense fats to separate from the liquid and float up . after being skimmed off , this fat , known as butterfat , can be used in dairy products like butter , cream , and cheese . or it can be later added back to the liquid in varying proportions to yield different fat content milks . full fat milk , sometimes referred to as whole milk , has 3.25 % butterfat added compared to 1-2 % for low and reduced fat milk , and less than half a percent for skim milk . to stop reseparation of the fat from the water , or creaming , the mixture undergoes the high-energy pressurized process of homogenization . before milk hits the shelves , it 's also typically heat treated to reduce its level of microbes , a government-sanctioned process that raw milk enthusiasts argue may reduce milk 's nutritional worth . milk spoilage is started by microbes , which consume and break down the nutrients in milk . that process causes butterfat to clump together , leading to a visually unpleasant product . and the byproducts of the microbes ' consumption are compounds that taste and smell nasty . but there 's a bigger problem . raw milk can carry microbes that are the sources of deadly diseases , so in order to kill as many of those microbes as possible , and keep milk fresh longer , we use a technique called pasteurization . one version of this process involves exposing milk to about 30 seconds of high heat . another version , called ultra-high temperature processing , or ultra pasteurization , blasts the milk with considerably higher temperatures over just a few seconds . uht milk boasts a much longer shelf life , up to twelve months unrefrigerated , compared to pasteurized milk 's two weeks in the fridge . that 's because the higher temperatures of uht processing inactivate far more microbes . yet the higher processing temperatures may adversely affect the nutritional and sensory properties of the milk . ultimately , that choice lies in the consumer 's taste and need for convenience . fortunately , there are many choices available in an industry that produces in excess of 840 million tons of products each year .
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although this process is typically reserved for females , in some species , like dayak fruit bats , goats , and even cats , males can also lactate . milk drinkers worldwide consume dairy from buffalo , goats , sheeps , camels , yaks , horses , and cows . almost all of these species are ruminants , a type of mammal with four-chambered stomachs that yield large quantities of milk .
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fermented dairy drinks are particularly popular in south east asia compared to other parts of the world . what is one of the main reasons these drinks are consumed more in south east asia ?
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today when people complain about the state of american politics , they often mention the dominance of the democratic and republican parties , or the sharp split between red and blue states . but while it may seem like both of these things have been around forever , the situation looked quite different in 1850 , with the republican party not yet existing , and support for the dominant democrats and whigs cutting across geographic divides . the collapse of this second party system was at the center of increasing regional tensions that would lead to the birth of the republican party , the rise of abraham lincoln as its leader , and a civil war that would claim over half a million lives . and if this collapse could be blamed on a single event , it would be the kansas-nebraska act of 1854 . the story starts with the missouri compromise of 1820 . to balance the number of slave states and free states in the union , it allowed slavery in the newly admitted state of missouri , while making it off limits in the remaining federally administered louisiana territory . but compromises tend to last only as long as they 're convenient , and by the early 1850s , a tenacious democratic senator from illionis named stephen a. douglas found its terms very inconvenient . as an advocate of western expansion , he promoted constructing a transcontinental railroad across the northern plains with an eastern terminus in chicago , where he happened to own real estate . for his proposal to succeed , douglas felt that the territories through which the railroad passed , would have to be formally organized , which required the support of southern politicians . he was also a believer in popular sovereignty , arguing that the status of slavery in a territory should be decided by its residents rather than congress . so douglas introduced a bill designed to kill two birds with one stone . it would divide the large chunk of incorporated land into two new organized territories : nebraska and kansas , each of which would be open to slavery if the population voted to allow it . while douglas and his southern supporters tried to frame the bill as protecting the political rights of settlers , horrified northerners recognized it as repealing the 34-year-old missouri compromise and feared that its supporters ' ultimate goal was to extend slavery to the entire nation . congress was able to pass the kansas-nebraska act , but at the huge cost of bitterly dividing the nation , with 91 % of the opposition coming from northerners . in the house of representatives , politicians traded insults and brandished weapons until a sargent at arms restored order . president pierce signed the bill into law amidst a storm of protest , while georgia 's alexander stephens , future confederate vice president , hailed the act 's passage as , `` glory enough for one day . '' the new york tribune reported , `` the unanimous sentiment of the north is indignant resistance . '' douglas even admitted that he could travel from washington d.c. to chicago by the light of his own burning effigies . the political consequences of the kansas-nebraska act were stunning . previously , both whigs and democrats had included northern and southern lawmakers united around various issues , but now slavery became a dividing factor that could not be ignored . congressmen from both parties spoke out against the act , including an illinois whig named abraham lincoln , denouncing `` the monstrous injustice of slavery '' in an 1854 speech . by this time the whigs had all but ceased to exist , irreparably split between their northern and southern factions . in the same year , the new republican party was founded by the anti-slavery elements from both existing parties . although lincoln still ran for senate as a whig in 1854 , he was an early supporter of the new party , and helped to recruit others to its cause . meanwhile the democratic party was shaken when events in the newly formed kansas territory revealed the violent consequences of popular sovereignty . advertisements appeared across the north imploring people to emigrate to kansas to stem the advance of slavery . the south answered with border ruffians , pro-slavery missourians who crossed state lines to vote in fraudulent elections and raid anti-slavery settlements . one northern abolitionist , john brown , became notorious following the pottawatomie massacre of 1856 when he and his sons hacked to death five pro-slavery farmers with broad swords . in the end , more than 50 people died in bleeding kansas . while nominally still a national party , douglas 's democrats were increasingly divided along sectional lines , and many northern members left to join the republicans . abraham lincoln finally took up the republican party banner in 1856 and never looked back . that year , john c. fremont , the first republican presidential candidate , lost to democrat , james buchanan , but garnered 33 % of the popular vote all from northern states . two years later , lincoln challenged douglas for his illinois senate seat , and although he lost that contest , it elevated his status among republicans . lincoln would finally be vindicated in 1860 , when he was elected president of the united states , defeating in his own home state , a certain northern democrat , who was finally undone by the disastrous aftermath of the law he had masterminded . americans today continue to debate whether the civil war was inevitable , but there is no doubt that the kansas-nebraska act made the ghastly conflict much more likely . and for that reason , it should be remembered as one of the most consequential pieces of legislation in american history .
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douglas even admitted that he could travel from washington d.c. to chicago by the light of his own burning effigies . the political consequences of the kansas-nebraska act were stunning . previously , both whigs and democrats had included northern and southern lawmakers united around various issues , but now slavery became a dividing factor that could not be ignored .
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in the 1850s , most white northerners were not abolitionists and yet there was widespread opposition in the north to the kansas-nebraska act . why ?
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... and i 'm scratching , and i like to hide . oh , i am such a good spider . i will turn this way , and i will , let 's see ... i will hide now . ah , with a scratch scratch scratch scratch scratch scratch scratch ! and i will flatten myself like this ! and now i 'm hiding , and i can see you . i like looking at you ... but wait a minute . if i can see you then you can see me ... meh , and it *is* a bit drafty in here , i must say . so maybe i 'm not hidden . i will turn this way . yes ? and i will – i will scratch scratch scratch scratch scratch scratch scratch scratch ! and that will bury myself again , and i will flatten my legs this time that was the problem last time – my legs were not flattened , so i flat – no ! but i still bury– oh hon hon hon hon honn hon hon honnnn ! here is the secret key ! i can not be you , that they you can not see me ... i am hidden !
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... and i 'm scratching , and i like to hide . oh , i am such a good spider .
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what point of view allows the author the greatest flexibility and is most commonly used ?
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living with her family high above the ground in the northern tropical forests of colombia , you will find shakira , a cotton-top tamarin with a penchant for conversation . say , `` hola ! '' though you may not realize it , this one pound monkey communicates in a highly sophisticated language of 38 distinct calls based on variations of chirps and whistles . the response she just gave is known as a `` b chirp '' , a call often directed at humans . to appreciate the complexities of shakira 's language , let 's learn a few chirps and whistles , then examine how their combinations form grammatically structured sequences . the chirp shakira used to greet us comes from a class of calls known as single frequency modulated syllables . this class is made up of short duration calls , or chirps , and long duration calls , like screams and squeals . researchers have determined that there are eight different types of chirps categorized by stem upsweep , duration , peak frequency , and frequency change . in addition , each chirp has its own unique meaning . for example , shakira 's `` c chirp '' is used when she is approaching food , where as her `` d chirp '' is only used when she has the food in hand . single whistles also exhibit a unique intention with each call and just as there are eight different chirps , there are five different whistles . based on frequency modulation , single whistles are subdivided into four categories : squeaks , initially modulated whistles , terminally modulated whistles , and flat whistles . the language 's quality of unique intention is wonderfully exemplified by the category of initially modulated whistles . these whistles change based on the proximity of shakira to other members of her family . if shakira is greater than .6 meters from her family , she 'll sound a large initally modulated whistle . but if she 's less than .6 meters from her family , she 'll sound a small initially modulated whistle . now that we 've learned a few chirps and whistles , shakira wants to show off by taking you through a quick day in her life with these calls . while heading towards a feeding tree for her first meal of the day , she says , ( monkey noise ) , a call most often used in relaxed investigations . however , suddenly she spots the shadow of a hawk . `` e chirp '' for alarm . this call alerts her family to the presence of this predator , and shakira jumps to the safety of an inner branch . the coast seems clear , so shakira makes her way towards her dad . wait , wait . who is that ? ah , it 's her younger brother , carlos . cotton-top tamarins often squeal during play wrestling . uh-oh . he 's playing a little too roughly , and shakira screams , alerting her parents to help her . her dad makes his way towards the ball of rolling fur and her brother stops . shakira shakes herself and scratches herself to get the hair on her head back in place . then shakira spots another group of unfamiliar tamarins and hears their normal long call . she turns to her family . ( monkey noise ) did you catch that ? first there was a chirp , then a whistle . this is what 's known as a combination vocalization , a phrase that contains both a chirp and a whistle . these are two calls strung together to convey a message . the combination of these two elements alerts her family to the presence of another group , the `` f chirp '' , and the distance they are away , the normal long call whistle . in other words , shakira just said a sentence . her simple demonstration is just the tip of the iceberg . she 's got trills , chatters , multiple whistle calls , more combination vocalizations , even twitters . yet sadly enough , we may not get to hear everything she has to say . mixed in with chirping sonatas from high above is the constant thud of a machete chopping trees . shakira 's habitat in colombia is being cut down , piece by piece , and if we do n't work to protect the critically endangered cotton-top tamarin , it will become extinct in our lifetime . if the chirp from one tamarin to the next has proven to be more than just idle chit chat , imagine what else we have left to discover . imagine what else shakira can tell us .
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ah , it 's her younger brother , carlos . cotton-top tamarins often squeal during play wrestling . uh-oh .
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how do scientists determine the meaning of cotton-top tamarin vocalizations ?
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translator : andrea mcdonough reviewer : jessica ruby welcome to the department of plagiarism investigation . the d.p.i . has dealt with numerous complex cases in their effort to bring plagiarists to justice and to rescue purloined texts . the first form of plagiarism that the d.p.i . regularly encounters is known as brain child snatching , in honor of the latin word , plagiarius , from which plagiarism originates . brain child snatchers sneak up on innocent papers and copy and paste them without citing any sources , putting quotation marks around direct quotes or changing a word . they 've also been known to steal and hold particularly eloquent essays for ransom . when brain child snatchers get together , they form a kidnapping ring , which involves brain child snatching from multiple sources . some perpetrators have even been known to commit self-plagiarism , one of the laziest crimes in the annals of the d.p.i . also known as one-sided collaborators , these odd balls snatch up entire texts or small passages that they 've written before and present them as brand-new material . brain child snatchers and kidnapping rings are easy for the d.p.i . to catch . just paste a few passages into a search engine , and bam ! they 're caught red-handed . the more covert forms of plagiarism include the wild goose chase technique , in which plagiarists create fake authors , book titles , page numbers , or other information in order to cover up plagiarism . and the old synonym switcheroo in which plagiarists utilize a thesaurus as their main weapon . by substituting a synonym for nearly every word in the document and leaving the sentence structure and order of the ideas the same , plagiarists give legitimate paraphrasing a very bad name . shoddy paraphrasing is also a key part of variations on a smokescreen , a technique in which multiple passages are paraphrased , then pasted together into one . the thorniest issue that the d.p.i . deals with is the misconception that you can never be accused of plagiarism if you use quotes and cite your sources . this is most certainly not the case because a paper that is made up of passage upon passage of other people 's ideas is known as a wholly quotable document . this is considered plagiarism since there are no original thoughts in the work . similarly , passage after passage of too closely paraphrased text from multiple cited sources is also plagiarism of the pervasively paraphrased kind because the ideas still are n't one 's own . and lastly , the technique of revealing while concealing is plagiarism because it involves selective amnesia regarding one 's sources in an attempt to cover up wholly quotable and pervasively paraphrased issues in a text . some passages are meticulously documented , quoted , or paraphrased , while others are presented entirely as one 's own . as you can see , the d.p.i . has its hands full , tackling all sorts of academic mischief and mayhem , ranging from the petty to the outrageous . given the gravity of these transgressions , you might be wondering why you 've never heard of the department of plagiarism investigation 's victories . that 's because it does n't technically exist . but people , like you and me , can be our own d.p.i . agents to fight plagiarism and uphold the values of original thinking . we know that the best defense against plagiarism consists of writers who save themselves time , worry , and effort by taking the far easier road of just doing the work themselves .
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they 're caught red-handed . the more covert forms of plagiarism include the wild goose chase technique , in which plagiarists create fake authors , book titles , page numbers , or other information in order to cover up plagiarism . and the old synonym switcheroo in which plagiarists utilize a thesaurus as their main weapon .
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lee forgets to write down the details regarding the online sources , interview subjects , and other information she used as she gathered information for her blog about the dpi ’ s most wanted plagiarists . running out of time , lee decides to fabricate the entire works cited section at the end of the blog post . what type of plagiarism did she commit ?
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indium is a very soft metal . i haven ’ t got a sample here . it melts at 150 degrees or so . this is an example of indium it is a really , really quite nice chemical element this one . we can use it for lots and lots of selective types of catalysis , but generally when it is forming a complex with other organic ligands . but here we can see a really nice example of indium and this is 99.9 % pure . but it ’ s a metal which has suddenly become very much more expensive because its oxide is transparent to light but will conduct electricity . so it is indium oxide that you find on every lcd display . here is a rather old computer and here is an old fashioned computer , the lcd display was quite small and gradually they have got bigger and bigger and therefore demand for indium oxide is more and more and probably you are watching this video clip through a thin layer of indium oxide . this sample although it ’ s very small , is 5 grams . so it is a really , really , dense metal , very , very expensive and very , very valuable as well . but indium is also used as solder for soldering various metals together and it is also quite useful if , i used it in my youth , when we were making low temperature apparatus and we wanted to screw two things together and get a nice seal in between them , you could screw them together with a thin sheet of indium , and that almost welded them together . so indium wire ; it is very , very malleable and very , very soft and very easy to form into shapes . i am not going to touch it though because it will cause some significant problems for me , because it does cause toxicity if it comes into contact with the skin ; so lovely piece of indium wire .
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but here we can see a really nice example of indium and this is 99.9 % pure . but it ’ s a metal which has suddenly become very much more expensive because its oxide is transparent to light but will conduct electricity . so it is indium oxide that you find on every lcd display . here is a rather old computer and here is an old fashioned computer , the lcd display was quite small and gradually they have got bigger and bigger and therefore demand for indium oxide is more and more and probably you are watching this video clip through a thin layer of indium oxide .
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indium oxide is transparent to light but it conducts electricity . this property means it can be found where ?
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- so the other group of ants [ dr. corrie moreau , curator/ants ] that we have today are bullet ants . [ dr. corrie moreau , curator/ants ] - why are they called bullet ants ? [ bullet ant , paraponera clavata ] - well , they 're called bullet ants [ bullet ant , paraponera clavata ] because their sting is so painful [ * causing excruciating pain , numbness & amp ; amp ; trembling ] it feels like you were shot by a gun . [ * causing excruciating pain , numbness & amp ; amp ; trembling ] - and you 've experienced this firsthand ? - i have , just once , i 'd like to keep it that way . and so you can see they 're actually quite tremendous ants , i mean , they 're really foreboding , [ * worker bullet ants are 18–30 mm long ] they 're crazy big and they 're cool . [ * worker bullet ants are 18–30 mm long ] - are they the largest ant ? - they 're one of the largest ants . there 's another genus called dinoponera . [ dinoponera , dinoponera australis ] in some ways larger . [ * females may surpass 30–40 mm in length ] not as painful of a sting , though . [ * females may surpass 30–40 mm in length ] this is paraponera . [ bullet ant , paraponera clavata ] we 're studying the gut bacteria actually in this group of ants . but we 're also interested in the venom . and so what i was telling you is part of the reason i brought them back alive is that at one point i had tried to milk them , because my colleague was like , `` it 's because we were n't sure if we 'd have permits to bring back alive . '' - yeah . - you can just milk them . so i can show you how i attempted to do it and i will tell you that it did n't work in the end . when i got the venom back it was actually not usable . but let me grab my equipment . - it 's not every day you get to milk a venomous ant . at work . - so this is our fancy equipment . so if you think about , like , how they milk the venom from spiders , right ? usually they just have them bite something and squirt the venom inside and it 's the same principle . so again , we just have our empty tubes , and we have a little bit of parafilm , right , which is essentially just like a waxy kind of paper-y thing that we can stretch across the top of this . and we 're going to get them to try to sting through the tube and deposit their venom on the side of the tube . - wow . - yeah . one thing i have noticed is , what 's really interesting actually , is with these bullet ants , when you collect them in the wild they 're incredibly aggressive . you disturb them at all , and they just go into immediate attack mode . in fact in the field , if you even like blow on them , you can physically hear them stridulate , which is a way of communicating between individuals . and now that they 've been in the lab for just a few days , they 're actually almost docile . and so i 'm curious to see whether they 'll even sting through this . but we 'll try . yeah , see , this one stridulates . so now let 's see if we put her abdomen up , yeah , she is depositing her sting through . - oh ! - see that ? - sting it ! sting it ! - so you see , she 's got her sting out , this is where i do n't want to lose control of her . she 'll try to sting through , oh , there , you saw that sting go ? that 's huge . - yeah . wow . focus your anger . - we will try to get another one to sting - come on , ladies . - you look like a new victim , raaah , let 's get her all mad . - yeaaaah ! oh , she 's stridulating . - she 's actually kinda not mad as much anymore . - they're—they 're just like , they 're like , `` corrie , we wan na hang out , i thought we were cool . '' - i know , that 's probably exactly what they think . - like , `` come on , corrie , '' `` i read your latest paper about climactic regional distribution '' `` of my sister species . '' i do n't even know if that 's what you 've written about , i do n't even know if that— those words even make sense . - you do n't read all my scientific publications ? - um , i probably could n't get through the abstract . not—not just yours , but most . - i wo n't take it personally . oh , yeah , she 's got a very big sting , so let 's see if i can get her to— - yeah . sting it . - so that 's how you milk a bullet ant for their venom . so essentially , just getting them to sting through this material , they have now deposited their venom all over the top of this and inside of that tube , so i can just shove that in there and then take it back to an analytical lab to look at what are the—what 's the chemistry within the venom . now , i 've already told you that that did n't work so successfully , so in a sense , what we need to do is dissect out the venom glad , and that 's where it gets a little more tricky , because in this case , you can see they 're big and— - cranky . - cranky . and they do n't like to hold still . do this under the microscope . okay , so now , again , we 're gon na just pull off her abdomen , oh god , these are some tough ants . [ * abdomen ] even tougher than the bullet ants . - wow . - so now we 've got— - you did it . - —her body separated from her abdomen . i wan na just tease apart some of the parts of the abdomen and then we can usually pull the venom gland out through the sting . so i 'm just gon na start pulling apart the body , and since i do n't want to rupture the venom gland , i wan na try not to stab too much . - yeah , this is meticulous work , dissecting ants . - yeah . - what is the smallest ant that you 'll work on under a microscope ? - oh , i 'll work on anyone . - even the ones that are so small that you ca n't even see them on the labels ? - yep , even those . i 've had to dissect out their guts , too . - how do you even get forceps that small ? - suspense , right ? - yeah , the pressure . - yeah , nothing like having to dissect on camera , too . as if it 's not hard enough , right ? - yeah , all the viewers are at home , quietly judging you . they 're like , `` well , when i dissected ants last— '' - i was thinking they were biting their fingernails in suspense . - yeah , that too . - so at the one end , let 's see if i can put it in a good orientation— you can actually see the left side , if you look through the microscope , you can actually see the sting hanging all the way out . [ * sting ] - oh yeah ! - it 's like a giant hypodermic needle . - yeah . - and then starting at the other end on the right side , we can actually start to see those parts of the digestive system . so first you have the crop , right ? [ * crop ] so it 's that social food sharing organ , which then transitions into the mid gut and then into what 's called the ileum [ * mid gut , * ileum ] and then finally into the rectum , [ * rectum ] and then alongside that is where the venom gland sits . [ * venom gland ] - that 's amazing . - yeah , it 's really awesome . one of the things that 's cool when you first open them up is that the contents within the gut , you can see fat and you can see the trachea and all those other things , and even within the gut , it 's either clear like it almost looks like water , or sometimes you can see things that look like waste , but within the venom sac , it 's actually almost like oil . and so when you burst it , it 's literally like oil coming out , not like liquid , like , you know , in the same sense . - cool . - yeah . - nice . - so now the question is , are you gon na hold a bullet ant for 10 seconds ? the brain scoop is brought to you by the field museum in chicago it still has brains on it .
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- so the other group of ants [ dr. corrie moreau , curator/ants ] that we have today are bullet ants . [ dr. corrie moreau , curator/ants ] - why are they called bullet ants ? [ bullet ant , paraponera clavata ] - well , they 're called bullet ants [ bullet ant , paraponera clavata ] because their sting is so painful [ * causing excruciating pain , numbness & amp ; amp ; trembling ] it feels like you were shot by a gun . [ * causing excruciating pain , numbness & amp ; amp ; trembling ] - and you 've experienced this firsthand ?
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why is this ant called the bullet ant ?
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[ ♪sustained note♪ ] [ flag flapping in breeze ] [ path of freedom ] [ ♪ music ♪ ] [ prisoners chattering ] [ ♪ music ♪ ] - this is a tough guy world , and we have to control all of their movement and their behavior [ roberta richman - rhode island dept . of corrections ] because that 's the way you keep an institution safe for everybody who lives in it . [ ♪ music ♪ ] we have everybody here— murderers and rapists , sex offenders , drug addicts— everybody . [ 1 out of every 100 americans is currently behind bars ] my name is dennis . i 'm 52 years old . i 'm serving a 15-year sentence for assaulting my wife . my name is louis , 35 . i sold narcotics [ clears throat ] since i was about 13 or so . my name is juan . i 'm 34 years old . i 'm here for second degree murder . yeah . sadly , this is my charge . my name is celine . i 'm 39 . i 'll be 40 soon . i was given a life term . [ ♪ music ♪ ] a lot of times what lands people in prison [ fleet maull - prison mindfulness institute ] and what brings them back is a lack of good problem-solving skills and good communication skills . [ ♪ music ♪ ] [ richman ] fleet approached us asking if he could do some work in here . we were challenged . our union wanted to know how we could possibly bring an ex-offender in . [ maull ] i served 14½ years on a 25-year , no parole sentence . hello . [ ♪ music ♪ ] having served 14 years boosts his credibility— boosts his credibility with inmates . how 's your week been ? - it 's good . [ maull ] yeah ? good . what 's up ? yeah . hey . welcome . when i got locked up , i really hit a wall of just seeing the craziness of my life path up until then and the incredible selfish decisions i 'd been making . my son was 9 years old . he was going to grow up without his dad . and i was just so deeply full of remorse and regret that i just literally started practicing meditation like my hair was on fire . so i became extremely motivated to turn my life around . [ ♪ music ♪ ] and so i was living the life of this prison monk . [ ♪ music ♪ ] i was sourcing a meditation group twice a week in the chapel . [ ♪ music ♪ ] i started receiving letters from prisoners while i was in prison . i had published some articles ; people knew about me out in the world a little bit , and they started sending some of these letters to me thinking i would know what to do with them . i worked in the education department , and i had access to a copy machine . i would copy articles out of books , and i 'd put together a little thing and i 'd send it off to a prisoner . so it started off that way , and i decided it was a much bigger deal than i could do from my prison cells . i think we have a co-creative relationship with our life . we ca n't control other people , we do n't control life , but is there some relationship between what we put out and what comes back ? freedom before i came here was just another word . i had never been to prison before . all you know is what the media and the movies say about prison— `` take care of yourself , man . '' `` somebody 's going to try to take your manhood or something . '' you know what i mean ? i 'm thinking i 'm going to come in here and fight the world . [ maull ] in a prison like moran , there 's a serious conflict waiting around any corner . it 's an environment where people 's worst behaviors are just right there just under the surface . [ ♪ music ♪ ] when i first came in , i fought with officers , would beat up anyone , would do the unthinkable just because . [ dennis ] it 's a vicious cycle because once you come to prison your life just keeps tumbling , tumbling , tumbling , and it 's like a never-ending wall that wo n't stop building unless you find some way to get over that wall or at least in front of it . [ richman ] what circumstances did they have to survive on the street to bring them to where they are now ? do we want to save those lives , or do we want to discard them ? the crimes i committed , i brought shame to not only myself but to those who i love . so i 'm just really trying to do something to get out of that cycle . somebody 's given us an opportunity just to meditate and connect ourselves , and that 's golden . so sit up with that good posture , just rest your hands on your legs , and just take a moment to just feel . [ ♪ music ♪ ] [ richman ] i 've always thought that the people who survive are so much stronger than i could ever be . i asked fleet how he survived and thrived the way he has . he credits meditation for having given him the strength to live his life in prison and come out not as much the worse for wear as most people do . i do n't have a release date . so i can only go home when they decide i can . so i learned to live day by day , and that helped me to deal with prison , and i could only do that being in the moment , being in the now . [ ♪ music ♪ ] it 's like if i do n't like what 's going on , what can i do to shift it ? if i do n't like the relationship i have with my boss or with one of the cos or something , could i approach that person in a different way ? can i get creative about what i 'm doing to bring about a shift in the way things are— in other words , owning my own situation . so how do you resolve that ? i take a breath and then [ chuckles ] i step back . really , you have to . [ maull ] then suddenly get that there 's this whole thing there that they thought was who they are . that 's the only reality they knew . suddenly they get to step outside of that a little bit . you just see the lights go on . it 's like this sudden illumination . it 's like a mini enlightenment of sorts . and that 's very powerful . that 's what keeps me coming . the reality of it is i 'm living life , and meditation it has brought a new perspective in the way that it gave me like a tool to really look inside myself and change the way i am . [ richman ] people do n't understand the value of what they call the soft stuff , and i sometimes think without the soft stuff , no matter how much hard stuff you have , you 're bound to fail . you can live your life . you can be yourself . you can show others that this is n't a place to breed a better criminal ; this could actually be a place to breed a better person . you 're here because the way that you were did n't work . so why not be better ? [ prisoners chattering ] [ richman ] the people in prison are us . they 're not monsters . and more importantly , whether we want them to or not , they 're getting out . so do you want them to come out angrier and meaner and more dangerous than they were when they came in , or do you want to do whatever you can to change their behavior while they 're here ? we need people to see and experience prisoners stepping out of that culture and doing something transformative with their lives , and then people will start to have faith , people will see people coming back to their community and they realize these are human beings and that human beings ' lives have value and they 're not expendable . [ ♪ music ♪ ] [ this year 700,000 people will return home from prison ] [ ♪ music ♪ ] [ directed by emmanuel vaughan-lee , produced by dorothee royal-hedinger ] [ cinematography by elias koch , edited by adam loften , sound recording by emmanuel vaughan-lee ] [ music by h. scott salinas , sound mix by d. chris smith ] [ www.globalonenessproject.org ]
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we ca n't control other people , we do n't control life , but is there some relationship between what we put out and what comes back ? freedom before i came here was just another word . i had never been to prison before .
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one prisoner explained , `` freedom before i came here was just another word . '' maull believes that freedom can be found while being in prison . what does freedom mean to you ?
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translator : andrea mcdonough reviewer : jessica ruby your car , the heating system in your house , your gas stove . most of the energy you use comes from fossil fuels , which present a couple of problems . first , there are limited supplies of fossil fuels , so the more we use , the less we 've got . and second , the use of fossil fuels is the main cause of climate change because it releases large amounts of carbon dioxide into the atmosphere . biofuels come from natural , renewable sources like plants , so they have the potential to reduce our reliance on those limited supply fossil fuels and reduce the risk of climate change . most biofuels today are made from corn grain that is fermented into ethanol . but we have a limited supply of this corn , so it 's not a solution to the limited supply part of the quandary . it also takes a lot of resources to grow corn grain . strike 2 ! a potential solution : using cellulose instead of corn grain to make ethanol . cellulose is far more abundant than corn grain and takes less energy to produce . in fact , it 's the most abundant organic molecule on the planet ! cellulose is the main ingredient found in a plant 's cell wall . plants generate cellulose from water and carbon dioxide during photosynthesis . so , where as using fossil fuels produce carbon dioxide , using cellulose-based ethanol might help remove carbon dioxide from the atmosphere . the main obstacle is that the cellulose molecule , a long , connected chain of glucose sugar protected by a tough , molecular sheath , is difficult to break apart . creating cellulose-based ethanol means first unwrapping that protective sheath and then chopping up the cellulose into its individual glucose molecule . only once we have unpacked each glucose molecule , can we begin fermentation . but some microorganisms , like bacteria or fungi , break down cellulose for energy all the time . for example , dairy cows eat foods like hay or alfalfa , which are full of cellulose . microbes that live in their stomachs produce an enzyme called cellulase , which breaks apart the cellulose molecules so that the cow can use what 's left for energy . researchers are now studying these kinds of microorganisms in the hopes of finding better ways to break down cellulose so we can use it for our own energy needs . the solution , they think , lies in finding microbes in nature that can produce the kinds of cellulase enzymes that we need . this process of searching for species in nature that can produce valuable products is called bioprospecting . to test whether or not a sample of microbes can break down cellulose effectively , researchers first grow the microbe in a test tube . then , they add a source of cellulose as the sole form of energy . if the microbe ca n't produce cellulase and break down cellulose , the test tube will remain unchanged . but if the microbe produces the enzymes we are looking for , it will be able to break down cellulose , use it for energy , and thrive in its test tube environment . if our microbial sample can break down the cellulose in the test tube , there is a chance we could use it to create a renewable and sustainable source of fuel for our cars from cellulose .
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translator : andrea mcdonough reviewer : jessica ruby your car , the heating system in your house , your gas stove . most of the energy you use comes from fossil fuels , which present a couple of problems . first , there are limited supplies of fossil fuels , so the more we use , the less we 've got .
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explain what two major problems occur as a result of using fossil fuels for energy and how the use of biofuels might negate these problems .
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in medieval times , alchemists tried to achieve the seemingly impossible . they wanted to transform lowly lead into gleaming gold . history portrays these people as aged eccentrics , but if only they 'd known that their dreams were actually achievable . indeed , today we can manufacture gold on earth thanks to modern inventions that those medieval alchemists missed by a few centuries . but to understand how this precious metal became embedded in our planet to start with , we have to gaze upwards at the stars . gold is extraterrestrial . instead of arising from the planet 's rocky crust , it was actually cooked up in space and is present on earth because of cataclysmic stellar explosions called supernovae . stars are mostly made up of hydrogen , the simplest and lightest element . the enormous gravitational pressure of so much material compresses and triggers nuclear fusion in the star 's core . this process releases energy from the hydrogen , making the star shine . over many millions of years , fusion transforms hydrogen into heavier elements : helium , carbon , and oxygen , burning subsequent elements faster and faster to reach iron and nickel . however , at that point nuclear fusion no longer releases enough energy , and the pressure from the core peters out . the outer layers collapse into the center , and bouncing back from this sudden injection of energy , the star explodes forming a supernova . the extreme pressure of a collapsing star is so high , that subatomic protons and electrons are forced together in the core , forming neutrons . neutrons have no repelling electric charge so they 're easily captured by the iron group elements . multiple neutron captures enable the formation of heavier elements that a star under normal circumstances ca n't form , from silver to gold , past lead and on to uranium . in extreme contrast to the million year transformation of hydrogen to helium , the creation of the heaviest elements in a supernova takes place in only seconds . but what becomes of the gold after the explosion ? the expanding supernova shockwave propels its elemental debris through the interstellar medium , triggering a swirling dance of gas and dust that condenses into new stars and planets . earth 's gold was likely delivered this way before being kneaded into veins by geothermal activity . billions of years later , we now extract this precious product by mining it , an expensive process that 's compounded by gold 's rarity . in fact , all of the gold that we 've mined in history could be piled into just three olympic-size swimming pools , although this represents a lot of mass because gold is about 20 times denser than water . so , can we produce more of this coveted commodity ? actually , yes . using particle accelerators , we can mimic the complex nuclear reactions that create gold in stars . but these machines can only construct gold atom by atom . so it would take almost the age of the universe to produce one gram at a cost vastly exceeding the current value of gold . so that 's not a very good solution . but if we were to reach a hypothetical point where we 'd mined all of the earth 's buried gold , there are other places we could look . the ocean holds an estimated 20 million tons of dissolved gold but at extremely miniscule concentrations making its recovery too costly at present . perhaps one day , we 'll see gold rushes to tap the mineral wealth of the other planets of our solar system . and who knows ? maybe some future supernova will occur close enough to shower us with its treasure and hopefully not eradicate all life on earth in the process .
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instead of arising from the planet 's rocky crust , it was actually cooked up in space and is present on earth because of cataclysmic stellar explosions called supernovae . stars are mostly made up of hydrogen , the simplest and lightest element . the enormous gravitational pressure of so much material compresses and triggers nuclear fusion in the star 's core .
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how are the lightest elements made ?
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each spring , nature lovers eagerly greet the signs that winter is finally coming to an end . as the days grow warmer , the flowers and trees start to bloom , and the world comes alive with the melodious call of birds in search of a new mate . but where have these enchanting sounds been hiding all winter ? for almost 200 species of song birds , their winters have been spent down in the tropical climates of central and south america . while this may sound ideal , it involves one of the most perilous journeys known in the entire animal kingdom . this journey is called migration , and for song birds , this can involve travelling somewhere between a few hundred to almost 7,000 miles in a period of several weeks to four months . birds spend weeks preparing for the intense journey by gorging on large quantities of food , sometimes doubling their weight prior to departure . while flying , birds can lose almost one percent of their body weight an hour , so packing on the pounds is crucial to their survival . however , more than the physical stress , migrating birds are now facing a new source of hardship : landscape change . just imagine you 're the one getting ready to take a trip . you 've packed the car with everything you think you need , fueled up the tank , eaten a huge breakfast , and hit the road . you 've taken this journey before . you know all your favorite rest stops and little back-alley diners to grab a bite . everything is planned out . but just as your fuel gauge starts dipping into the red zone , you pass by what should have been a gas station , except it 's closed . `` not a problem , '' you think , `` the next one ca n't be too far away . '' but then that next station never appears . unfortunately , as you continue on your route , the reality of the situation starts to set in . more and more stations are closed or just erased from your map . all of a sudden , your routine trip has become a desperate search just to find somewhere safe to rest and refuel for the night . this scenario has become the reality for the majority of migrating song birds as human land development continues unchecked . humans are altering important stop-over sites that birds have been using for generations . as migrators pass over the continent , they run a gauntlet of dangers , including pesticide ingestion in rural farmlands , habitat loss in suburban developments , as well as disorientation from light pollution , and even structure collision with tall , reflective glass buildings in cities . of the estimated 20 billion individual birds that comprise the fall population , only about half will return to breed the following spring . almost one billion of these deaths are attributed just to building collisions . with such astounding yearly losses , humans risk more than just the loss of the beautiful colors and songs of birds , they also play an important role in the ecosystem . birds help with insect control , pollination , and disbursing seeds throughout the landscape . without birds , the natural world would be a very different place . although birds face an on-going threat from human land development , there are actions that we can all take to help . many countries and local governements have already passed important laws that restrict the use of poisonous pesticides . by using more natural , plant-based products , we can maintain our farms and gardens without the dangerous side effects . in addition , as our global populations continue to grow and people need places to call home , green spaces can offer both bird habitat as well as a peaceful and natural place for us to enjoy . small changes at home can also make a huge difference . by hanging up feeders and building bird houses in outdoor areas , we can provide much-needed food and safety during long migrations . turning out lights in suburban and urban environments can also help birds that look for stars to navigate . with our help , these sky travellers can reach their destination safely , and hopefully keep returning year after year .
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although birds face an on-going threat from human land development , there are actions that we can all take to help . many countries and local governements have already passed important laws that restrict the use of poisonous pesticides . by using more natural , plant-based products , we can maintain our farms and gardens without the dangerous side effects .
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about how many species of songbirds migrate ?
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take a look out your window , put on your glasses if you wear them . you might want to grab a pair of binoculars , too , or a magnifying lens . now , what do you see ? well , whatever it is , it 's not the multiple layers of glass right in front of you . but have you ever wondered how something so solid can be so invisible ? to understand that , we have to understand what glass actually is , and where it comes from . it all begins in the earth 's crust , where the two most common elements are silicon and oxygen . these react together to form silicon dioxide , whose molecules arrange themselves into a regular crystalline form known as quartz . quartz is commonly found in sand , where it often makes up most of the grains and is the main ingredient in most type of glass . of course , you probably noticed that glass is n't made of multiple tiny bits of quartz , and for good reason . for one thing , the edges of the rigidly formed grains and smaller defects within the crystal structure reflect and disperse light that hits them . but when the quartz is heated high enough the extra energy makes the molecules vibrate until they break the bonds holding them together and become a flowing liquid , the same way that ice melts into water . unlike water , though , liquid silicon dioxide does not reform into a crystal solid when it cools . instead , as the molecules lose energy , they are less and less able to move into an ordered position , and the result is what is called an amorphous solid . a solid material with the chaotic structure of a liquid , which allows the molecules to freely fill in any gaps . this makes the surface of glass uniform on a microscopic level , allowing light to strike it without being scattered in different directions . but this still does n't explain why light is able to pass through glass rather than being absorbed as with most solids . for that , we need to go all the way down to the subatomic level . you may know that an atom consists of a nucleus with electrons orbiting around it , but you may be surprised to know that it 's mostly empty space . in fact , if an atom were the size of a sports stadium , the nucleus would be like a single pea in the center , while the electrons would be like grains of sand in the outer seats . that should leave plenty of space for light to pass through without hitting any of these particles . so the real question is not why is glass transparent , but why are n't all materials transparent ? the answer has to do with the different energy levels that electrons in an atom can have . think of these as different rows of seats in the stadium stands . an electron is initially assigned to sit in a certain row , but it could jump to a better row , if it only had the energy . as luck would have it , absorbing one of those light photons passing through the atom can provide just the energy the electron needs . but there 's a catch . the energy from the photon has to be the right amount to get an electron to the next row . otherwise , it will just let the photon pass by , and it just so happens that in glass , the rows are so far apart that a photon of visible light ca n't provide enough energy for an electron to jump between them . photons from ultraviolet light , on the other hand , give just the right amount of energy , and are absorbed , which is why you ca n't get a suntan through glass . this amazing property of being both solid and transparent has given glass many uses throughout the centuries . from windows that let in light while keeping out the elements , to lenses that allow us to see both the vast worlds beyond our planet , and the tiny ones right around us . it is hard to imagine modern civilization without glass . and yet for such an important material we rarely think about glass and its impact . it is precisely because the most important and useful quality of glass is being featureless and invisible that we often forget that it 's even there .
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from windows that let in light while keeping out the elements , to lenses that allow us to see both the vast worlds beyond our planet , and the tiny ones right around us . it is hard to imagine modern civilization without glass . and yet for such an important material we rarely think about glass and its impact .
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what are the physical origins of glass ?
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translator : andrea mcdonough reviewer : bedirhan cinar you might have heard that we 're running out of fresh water . this might sound strange to you because , if you live in a place where water flows freely from the tap or shower at any time , it sure does n't seem like a big deal . it 's just there , right ? wrong ! the only obvious thing about fresh water is how much we need it . because it 's essential to life , we need to think about it carefully . right now , at this very moment , some people , women and girls in particular , walk hours and miles per day to get fresh water , and even then , it may not be clean . every 15 seconds , a child dies due to water-born diseases . this is tragic ! the most compelling reasons to think about fresh water , therefore , have to do with what we might call the global common good . this is not something we normally think about , but it means recognizing how much fresh water matters for the flourishing of human and non-human life on earth now and in the future . how do we think about something as local as our faucets and as global as fresh water ? is there a connection between them ? many people assume that fresh water shortages are due to individual wastefulness : running the water while you brush your teeth , for example , or taking really long showers . most of us assume , therefore , that water shortages can be fixed by improving our personal habits : taking shorter showers or turning off the water while we brush our teeth . but , global fresh water scarcity neither starts nor ends in your shower . globally , domestic use of fresh water accounts for only 8 % of consumption , 8 % ! ! compare that to the 70 % that goes to agriculture and the 22 % that goes to industrial uses . now , hold up - you 're not off the hook ! individual habits are still part of the puzzle . you should still cultivate water virtue in your daily life , turn off the tap when you brush your teeth . but still , it 's true . taking shorter showers wo n't solve global problems , which is too bad . it would be much more straightforward and easier if virtuous , individual actions could do the trick . you 'd just stand there for 30 seconds less , and you 'd be done with that irksome , planet-saving task for the day . well , that 's not so much the case . agricultural and industrial patterns of water use need serious attention . how do our societies value water ? distribute it ? subsidize its use in agriculture ? incentivize its consumption or pollution ? these are all questions that stem from how we think about fresh water 's value . is it an economic commodity ? a human right ? a public good ? nobel prize winners , global water justice activists , transnational institutions like the united nations , and even the catholic church are at work on the issue . but , it 's tricky , too , because the business of water became very profitable in the 20th century . and profit is not the same thing as the common good . we need to figure out how to value fresh water as a public good , something that 's vital for human and non-human life , now and in the future . now that 's a virtuous , collective task that goes far beyond your shower .
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well , that 's not so much the case . agricultural and industrial patterns of water use need serious attention . how do our societies value water ? distribute it ?
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what are the two most water-using entities in the world ?
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it may seem like the semicolon is struggling with an identity crisis . it looks like a comma crossed with a period . maybe that 's why we toss these punctuation marks around like grammatical confetti . we 're confused about how to use them properly . in fact , it 's the semicolon 's half-half status that makes it useful . it 's stronger than a comma , and less final than a period . it fills the spaces in between , and for that reason , it has some specific and important tasks . for one , it can clarify ideas in a sentence that 's already festooned with commas . `` semicolons : at first , they may seem frightening , then , they become enlightening , finally , you 'll find yourself falling for these delightful punctuation marks . '' even though the commas separate different parts of the sentence , it 's easy to lose track of what belongs where . but then the semicolon edges in to the rescue . in list-like sentences , it can exert more force than commas do , cutting sentences into compartments and grouping items that belong together . the semicolon breaks things up , but it also builds connections . another of its tasks is to link together independent clauses . these are sentences that can stand on their own , but when connected by semicolons , look and sound better because they 're related in some way . `` semicolons were once a great mystery to me . i had no idea where to put them . '' technically , there 's nothing wrong with that . these two sentences can stand alone . but imagine they appeared in a long list of other sentences , all of the same length , each separated by periods . things would get monotonous very fast . in that situation , semicolons bring fluidity and variation to writing by connecting related clauses . but as beneficial as they are , semicolons do n't belong just anywhere . there are two main rules that govern their use . firstly , unless they 're being used in lists , semicolons should only connect clauses that are related in some way . you would n't use one here , for instance : `` semicolons were once a great mystery to me ; i 'd really like a sandwich . '' periods work best here because these are two totally different ideas . a semicolon 's job is to reunite two independent clauses that will benefit from one another 's company because they refer to the same thing . secondly , you 'll almost never find a semicolon willingly stationed before coordinating conjunctions : the words , `` and , '' `` but , '' `` for , '' `` nor , '' `` or , '' `` so , '' and `` yet . '' that 's a comma 's place , in fact . but a semicolon can replace a conjunction to shorten a sentence or to give it some variety . ultimately , this underappreciated punctuation mark can give writing clarity , force , and style , all encompassed in one tiny dot and squiggle that 's just waiting to be put in the right place .
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the semicolon breaks things up , but it also builds connections . another of its tasks is to link together independent clauses . these are sentences that can stand on their own , but when connected by semicolons , look and sound better because they 're related in some way .
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independent clauses :
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it may seem like the semicolon is struggling with an identity crisis . it looks like a comma crossed with a period . maybe that 's why we toss these punctuation marks around like grammatical confetti . we 're confused about how to use them properly . in fact , it 's the semicolon 's half-half status that makes it useful . it 's stronger than a comma , and less final than a period . it fills the spaces in between , and for that reason , it has some specific and important tasks . for one , it can clarify ideas in a sentence that 's already festooned with commas . `` semicolons : at first , they may seem frightening , then , they become enlightening , finally , you 'll find yourself falling for these delightful punctuation marks . '' even though the commas separate different parts of the sentence , it 's easy to lose track of what belongs where . but then the semicolon edges in to the rescue . in list-like sentences , it can exert more force than commas do , cutting sentences into compartments and grouping items that belong together . the semicolon breaks things up , but it also builds connections . another of its tasks is to link together independent clauses . these are sentences that can stand on their own , but when connected by semicolons , look and sound better because they 're related in some way . `` semicolons were once a great mystery to me . i had no idea where to put them . '' technically , there 's nothing wrong with that . these two sentences can stand alone . but imagine they appeared in a long list of other sentences , all of the same length , each separated by periods . things would get monotonous very fast . in that situation , semicolons bring fluidity and variation to writing by connecting related clauses . but as beneficial as they are , semicolons do n't belong just anywhere . there are two main rules that govern their use . firstly , unless they 're being used in lists , semicolons should only connect clauses that are related in some way . you would n't use one here , for instance : `` semicolons were once a great mystery to me ; i 'd really like a sandwich . '' periods work best here because these are two totally different ideas . a semicolon 's job is to reunite two independent clauses that will benefit from one another 's company because they refer to the same thing . secondly , you 'll almost never find a semicolon willingly stationed before coordinating conjunctions : the words , `` and , '' `` but , '' `` for , '' `` nor , '' `` or , '' `` so , '' and `` yet . '' that 's a comma 's place , in fact . but a semicolon can replace a conjunction to shorten a sentence or to give it some variety . ultimately , this underappreciated punctuation mark can give writing clarity , force , and style , all encompassed in one tiny dot and squiggle that 's just waiting to be put in the right place .
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maybe that 's why we toss these punctuation marks around like grammatical confetti . we 're confused about how to use them properly . in fact , it 's the semicolon 's half-half status that makes it useful .
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why do we use semicolons if we could just use commas and periods ? what advantage do they offer ? give an example of your own .
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in 1978 , louise brown became the world 's first baby to be born by in vitro fertilization , or ivf . her birth revolutionized the field of reproductive medicine . given that approximately one in eight heterosexual couples has difficulty conceiving , and that homosexual couples and single parents often need clinical help to make a baby , the demand for ivf has been growing . ivf is so common , that more than 5 million babies have been born through this technology . ivf works by mimicking the brilliant design of sexual reproduction . in order to understand ivf , we first need to take a look at the natural process of baby making . believe it or not , it all starts in the brain . roughly fifteen days before fertilization can happen , the anterior pituitary gland secretes follicle stimulating hormone , fsh , which ripens a handful of follicles of the ovary that then release estrogen . each follicle contains one egg , and on average , only one follicle becomes fully mature . as it grows and continues to release estrogen , this hormone not only helps coordinate growth and preparation of the uterus , it also communicates to the brain how well the follicle is developing . when the estrogen level is high enough , the anterior pituitary releases a surge of luteinizing hormone , lh , which triggers ovulation and causes the follicle to rupture and release the egg . once the egg leaves the ovary , it is directed into the fallopian tube by the finger-like fimbriae . if the egg is not fertilized by sperm within 24 hours , the unfertilized egg will die , and the entire system will reset itself , preparing to create a new egg and uterine lining the following month . the egg is the largest cell in the body and is protected by a thick , extracellular shell of sugar and protein called the zona pellucida . the zona thwarts the entry and fusion of more than one sperm , the smallest cell in the body . it takes a man two to three months to make sperm , and the process constantly renews . each ejaculation during sexual intercourse releases more than 100 million sperm . but only 100 or so will ultimately make it to the proximity of the egg , and only one will successfully penetrate through the armor of the zona pellucida . upon successful fertilization , the zygote immediately begins developing into an embryo , and takes about three days to reach the uterus . there , it requires another three or so days to implant firmly into the endometrium , the inner lining of the uterus . once implanted , the cells that are to become the placenta secrete a hormone that signals to the ovulated follicle that there is a pregnancy in the uterus . this helps rescue that follicle , now called the corpus luteum , from degenerating as it normally would do in that stage of the menstrual cycle . the corpus luteum is responsible for producing the progesterone required to maintain the pregnancy until six to seven weeks of gestation , when the placenta develops and takes over , until the baby is born approximately 40 weeks later . now , how do you make a baby in a lab ? in patients undergoing ivf , fsh is administered at levels that are higher than naturally occuring to cause a controlled overstimulation of the ovaries so that they ultimately produce multiple eggs . the eggs are then retrieved just before ovulation would occur , while the woman is under anesthesia , through an aspirating needle that is guided by ultrasound . most sperm samples are produced by masturbation . in the laboratory , the identified eggs are stripped of surrounding cells and prepared for fertilization in a petri dish . fertilization can occur by one of two techniques . in the first , the eggs are incubated with thousands of sperm and fertilization occurs naturally over a few hours . the second technique maximizes certainty of fertilization by using a needle to place a single sperm inside the egg . this is particularly useful when there is a problem with the quality of the sperm . after fertilization , embryos can be further screened for genetic suitability , frozen for later attempted pregnancies , or delivered into the woman 's uterus via catheter . common convention is to transfer the embryo three days after fertilization , when the embryo has eight cells , or on day five , when the embryo is called a blastocyst , and has hundreds of cells . if the woman 's eggs are of poor quality due to age or toxic exposures , or have been removed due to cancer , donor eggs may be used . in the case that the intended mother has a problematic uterus , or lacks one , another woman , called the gestational carrier or surrogate , can use her uterus to carry the pregnancy . to increase the odds of success , which are as high as 40 % for a woman younger than 35 , doctors sometimes transfer multiple embryos at once , which is why ivf results in twins and triplets more often than natural pregnancies . however , most clinics seek to minimize the chances of multiple pregnancies , as they are riskier for mothers and babies . millions of babies , like louise brown , have been born from ivf and have had normal , healthy lives . the long-term health consequences of ovarian stimulation with ivf medicines are less clear , though so far , ivf seems safe for women . because of better genetic testing , delayed childbearing , increased accessibility and diminishing cost , it 's not inconceivable that artificial baby making via ivf and related techniques could outpace natural reproduction in years to come .
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this helps rescue that follicle , now called the corpus luteum , from degenerating as it normally would do in that stage of the menstrual cycle . the corpus luteum is responsible for producing the progesterone required to maintain the pregnancy until six to seven weeks of gestation , when the placenta develops and takes over , until the baby is born approximately 40 weeks later . now , how do you make a baby in a lab ?
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the _____ is responsible for producing progesterone , the hormone that maintains a pregnancy .
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translator : jessica ruby reviewer : caroline cristal they 're long and slithery , and they 're not very colorful . but they do have a strange beauty of their own . their sinuous , nocturnal movements through the water are mesmerizing to watch . and though they may resemble underwater snakes , eels are , in fact , a very interesting type of fish . there are several things about eels that make them unique besides their elongated shape and limbless bodies . for one thing , eels have the ability to breathe through their skin . some can even leave the water and move over land for short periods . and , unlike most migratory fish , such as salmon , which spawn in fresh water but live their adult lives in salt water , eels of the genus anguilla migrate in the opposite direction , spawning and breeding in oceans and seas , while spending most of their intervening time in fresh water . if we were to take one such fresh water eel and follow its life story , it would be born in the middle of the north atlantic ocean , about a thousand miles east of bermuda . this area , called the sargasso sea , forms the western part of a subtropical gyre , a giant whirlpool in the middle of the ocean . our eel , let 's call it eli , would begin as one of ten to twenty million tiny eggs , carried by a female eel , hatching into a transparent leaf-shaped thing that looks nothing like an adult eel . eli starts to drift in ocean currents , predominantly the gulf stream towards either europe or north america , depending on its particular species . upon reaching the coast , eli is about two inches long , looking more eely but still transparent , known at this stage as a glass eel . but within a couple of days in fresh water , eli 's skin becomes pigmented a brownish-black , now looking more like that of an adult eel . you might notice that we have n't mentioned anything about eli 's gender yet . that 's because this is only determined once an eel enters fresh water , though nobody is sure exactly how that happens . most of the eels that stay in the estuaries and brackish water become males , while those that go upstream become females , growing up to two to three times bigger than their future mates . in this case , it turns out that eli was actually short for elaine . as a female eel , elaine will be quite solitary for most of her life in the stream , eating whatever falls in the water : grasshoppers , crickets , small fish , insect larvae , frogs , baby birds , almost anything she can get her mouth around . and she will grow quite big , up to four feet long and weighing as much as thirteen pounds . we do n't know exactly how fresh water eels know when it 's time to return to the ocean , but something calls to them . and their fall migration is one of the largest unseen migrations on the planet . as elaine leaves fresh water for the ocean , she undergoes a shocking metamorphosis . her eyes enlarge by about ten times , her skin gets thicker , and her fins get larger . these are most likely adaptations for their upcoming ocean travel , and elaine seamlessly makes the transition from fresh to salt water , which would be toxic for most other fish . once elaine leaves the mouth of the fresh water streams , she will disappear completely from human view . no one has witnessed , or been able to follow , an adult eel on their migration , nor do we know how deep they spawn . but it 's assumed that they can follow some signs that they can detect , such as a thermal barrier between ocean currents or a salinity front , in order to return to the same area of the ocean where they were born . because we do n't even know exactly what happens during an eel 's migration , we can only imagine what the actual breeding looks like . but the common hypothesis is that elaine and thousands , or hundreds of thousands , of other eels gather in large , intertwined masses and release their eggs and sperm in a giant orgy known as panmixia . a couple of days after the eggs are laid , they hatch , and the cycle begins again . and because we 've never seen the adult eels returning up the fresh water rivers , we must assume that , having completed their long and roundabout journey , these amazing and mysterious creatures finally die there , in the same place where they were born . goodbye , elaine ! it was a pleasure knowing you .
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their sinuous , nocturnal movements through the water are mesmerizing to watch . and though they may resemble underwater snakes , eels are , in fact , a very interesting type of fish . there are several things about eels that make them unique besides their elongated shape and limbless bodies .
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though they resemble underwater snakes , eels are a very interesting type of ________ .
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translator : andrea mcdonough reviewer : bedirhan cinar hello , my name is christian rudder , and i was one of the founders of okcupid . it 's now one of the biggest dating sites in the united states . like most everyone at the site , i was a math major , as you may expect , we 're known for the analytic approach we take to love . we call it our matching algorithm . basically , okcupid 's matching algorithm helps us decide whether two people should go on a date . we built our entire business around it . now , algorithm is a fancy word , and people like to drop it like it 's this big thing . but really , an algorithm is just a systematic , step-by-step way to solve a problem . it does n't have to be fancy at all . here in this lesson , i 'm going to explain how we arrived at our particular algorithm , so you can see how it 's done . now , why are algorithms even important ? why does this lesson even exist ? well , notice one very significant phrase i used above : they are a step-by-step way to solve a problem , and as you probably know , computers excel at step-by-step processes . a computer without an algorithm is basically an expensive paperweight . and since computers are such a pervasive part of everyday life , algorithms are everywhere . the math behind okcupid 's matching algorithm is surprisingly simple . it 's just some addition , multiplication , a little bit of square roots . the tricky part in designing it was figuring out how to take something mysterious , human attraction , and break it into components that a computer can work with . the first thing we needed to match people up was data , something for the algorithm to work with . the best way to get data quickly from people is to just ask for it . so we decided that okcupid should ask users questions , stuff like , `` do you want to have kids one day ? '' `` how often do you brush your teeth ? '' `` do you like scary movies ? '' and big stuff like , `` do you believe in god ? '' now , a lot of the questions are good for matching like with like , that is , when both people answer the same way . for example , two people who are both into scary movies are probably a better match than one person who is and one who is n't . but what about a question like , `` do you like to be the center of attention ? '' if both people in a relationship are saying yes to this , they 're going to have massive problems . we realized this early on , and so we decided we needed a bit more data from each question . we had to ask people to specify not only their own answer , but the answer they wanted from someone else . that worked really well . but we needed one more dimension . some questions tell you more about a person than others . for example , a question about politics , something like , `` which is worse : book burning or flag burning ? '' might reveal more about someone than their taste in movies . and it does n't make sense to weigh all things equally , so we added one final data point . for everything that okcupid asks you , you have a chance to tell us the role it plays in your life . and this ranges from irrelevant to mandatory . so now , for every question , we have three things for our algorithm : first , your answer ; second , how you want someone else -- your potential match -- to answer ; and third , how important the question is to you at all . with all this information , okcupid can figure out how well two people will get along . the algorithm crunches the numbers and gives us a result . as a practical example , let 's look at how we 'd match you with another person . let 's call him `` b . '' your match percentage with b is based on questions you 've both answered . let 's call that set of common questions `` s. '' as a very simple example , we use a small set `` s '' with just two questions in common , and compute a match from that . here are our two example questions . the first one , let 's say , is , `` how messy are you ? '' and the answer possibilities are : very messy , average and very organized . and let 's say you answered `` very organized , '' and you 'd like someone else to answer `` very organized , '' and the question is very important to you . basically , you 're a neat freak . you 're neat , you want someone else to be neat , and that 's it . and let 's say b is a little bit different . he answered `` very organized '' for himself , but `` average '' is ok with him as an answer from someone else , and the question is only a little important to him . let 's look at the second question , from our previous example : `` do you like to be the center of attention ? '' the answers are `` yes '' and `` no . '' you 've answered `` no , '' you want someone else to answer `` no , '' and the question is only a little important to you . now b , he 's answered `` yes . '' he wants someone else to answer `` no , '' because he wants the spotlight on him , and the question is somewhat important to him . so , let 's try to compute all of this . our first step is , since we use computers to do this , we need to assign numerical values to ideas like `` somewhat important '' and `` very important , '' because computers need everything in numbers . we at okcupid decided on the following scale : `` irrelevant '' is worth 0 . `` a little important '' is worth 1 . `` somewhat important '' is worth 10 . `` very important '' is 50 . and `` absolutely mandatory '' is 250 . next , the algorithm makes two simple calculations . the first is : how much did b 's answers satisfy you ? that is , how many possible points did b score on your scale ? well , you indicated that b 's answer to the first question , about messiness , was very important to you . it 's worth 50 points and b got that right . the second question is worth only 1 , because you said it was only a little important . b got that wrong , so b 's answers were 50 out of 51 possible points . that 's 98 % satisfactory . pretty good . the second question the algorithm looks at is : how much did you satisfy b ? well , b placed 1 point on your answer to the messiness question and 10 on your answer to the second . of those 11 , that 's 1 plus 10 , you earned 10 -- you guys satisfied each other on the second question . so your answers were 10 out of 11 equals 91 percent satisfactory to b . that 's not bad . the final step is to take these two match percentages and get one number for the both of you . to do this , the algorithm multiplies your scores , then takes the nth root , where `` n '' is the number of questions . because s , which is the number of questions in this sample , is only 2 , we have : match percentage equals the square root of 98 percent times 91 percent . that equals 94 percent . that 94 percent is your match percentage with b . it 's a mathematical expression of how happy you 'd be with each other , based on what we know . now , why does the algorithm multiply , as opposed to , say , average the two match scores together , and do the square-root business ? in general , this formula is called the geometric mean . it 's a great way to combine values that have wide ranges and represent very different properties . in other words , it 's perfect for romantic matching . you 've got wide ranges and you 've got tons of different data points , like i said , about movies , politics , religion -- everything . intuitively , too , this makes sense . two people satisfying each other 50 percent should be a better match than two others who satisfy 0 and 100 , because affection needs to be mutual . after adding a little correction for margin of error , in the case where we have a small number of questions , like we do in this example , we 're good to go . any time okcupid matches two people , it goes through the steps we just outlined . first it collects data about your answers , then it compares your choices and preferences to other people 's in simple , mathematical ways . this , the ability to take real-world phenomena and make them something a microchip can understand , is , i think , the most important skill anyone can have these days . like you use sentences to tell a story to a person , you use algorithms to tell a story to a computer . if you learn the language , you can go out and tell your stories . i hope this will help you do that .
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first it collects data about your answers , then it compares your choices and preferences to other people 's in simple , mathematical ways . this , the ability to take real-world phenomena and make them something a microchip can understand , is , i think , the most important skill anyone can have these days . like you use sentences to tell a story to a person , you use algorithms to tell a story to a computer .
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what does christian rudder say is the most important skill a person can have these days ?
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so in the bottom we see neon and this is a small glass discharge tube which has got a very low pressure of neon inside it . it ’ s generally used for lots of signs and things like that . you might see ‘ fish and chips ’ or perhaps a ‘ disco ’ or something like that . so neon is an inert gas like helium and it doesn ’ t really form any compounds at all . most of you have probably seen neon because it ’ s used in these so-called neon signs where you take a glass tube and put a high voltage and it produces a red light . so you can see that , again , a discharge , a high potential discharge is going across this tube and it ’ s exciting all of the neon molecules inside , such that we get this exciting , really vivid red colouration . and skilled glass-blowers can blow this into glass shapes of signs saying ‘ pizza ’ or whatever on shops . you can freeze neon at very low temperatures about 10 degrees absolute and early on in my scientific career i did do an experiment in solid neon . it produced a great result with an iron compound and i ’ m still quite proud of it several years on . but it ’ s not really very important in terms of absolute chemistry . so this is just a simple pocket spectroscope and it allows us to analyse the wavelengths of light that each of these individual light sources is giving off . so each individual atom as it ’ s excited in its emission zone can give rise to different lines or different frequencies of radiation or light and we can use this little device to analyse which elements are in each of these different elements of light . so we put it up to our eyes and we look through , and we look at the different colours of the lines in the different gases .
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so in the bottom we see neon and this is a small glass discharge tube which has got a very low pressure of neon inside it . it ’ s generally used for lots of signs and things like that . you might see ‘ fish and chips ’ or perhaps a ‘ disco ’ or something like that .
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what is the name of the instrument pete used to see the emission spectrum of excited neon ?
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translator : andrea mcdonough reviewer : bedirhan cinar fourth and nineteen , folks , they 've got ta have a play as time 's ticking away because they 've got to stay in this ball game , they 've got to win . they come out lined up in the empty set , three receivers to the right , two to the left . defense looks like they 're gon na to man up with no safety . this is the exact offensive match-up that they want : the best receiver lined up against the linebacker . quarterback steps back to receive the ball , five yards deep in the gun . he takes a snap , drops three steps , he plants his back foot , he 's looking for an opening . there 's a blitz coming off the edge ! he steps up to avoid the rush . he 's looking down field . he 's got the inside receiver making a cut . he 's got a step on the linebacker . quarterback has a beat on it . he lets the ball go , it 's in the air ! receiver is out in front of the defender . he 's got it beat ! he 's out in front , racing for the ball ! it 's coming down ! he cradles it at the fifteen ! he 's at the ten , five ! touchdown ! unbelievable play ! now , wait a minute . of course , it 's believable , it 's physics , specifically the differences between scalars and vectors . so , let 's just see that replay . `` quarterback steps back to receive the ball , five yards deep in the gun . '' stop . see , measurements are defined as two different quantities . scalars are measurements with only numbers , and vectors are measurements with direction . for example , when that quarterback takes the snap , he 's five yards away , but from where ? back from the line of scrimmage , so the five yards by itself is a scalar quantity . when you add a direction , like five yards deep , it becomes a vector quantity . five yards - scalar , five yards deep - vector . ok , go ahead . `` he takes a snap , drops three steps . he plants his back foot , he 's looking for an opening . there 's a blitz coming off the edge ! he steps up to avoid the rush . '' whoa ! here 's a difference between distance and displacement . distance is a measurement without identifying where you moved . it 's a scalar quantity . when the quarterback makes a three-step drop , he moves about three yards back . when he moves about another three yards forward , when he steps up into the pocket , so that quarterback moves a total distance of six yards . that 's a distance , that 's a scalar . now , displacement is a vector quantity , describing about how far out of place the object is . so the quarterback dropped back three yards and then moved back forward three yards , he 's in the exact same place where he started . so , his displacement is zero yards . distance - six yards , displacement - zero yards . so , let 's look at what happened next . `` quarterback has a beat on it , he let 's the ball go ! it 's in the air ! receiver is out in front of the defender . '' stop . so , here 's speed and velocity , but let 's just do one thing at a time . so , speed is measurement without direction , it 's a scalar quantity . velocity is a vector quantity . it is that object 's speed , but with a direction of motion . so the receiver accelerates away , gaining both speed and distance . this takes the receiver 5 seconds to run those 50 yards . so his average speed , in any given time , is 10 yards/second . the linebacker tries to keep up , but his overall speed is slower , he only goes 35 yards in those 5 seconds , so his average speed is only 7 yards/second . they 're both traveling in a forward direction , so their velocity is also positive . you ca n't go from resting to your peak speed immediately . you 've got to build up to it . this is acceleration . at first the linebacker can keep up with that receiver , but eventually the faster receiver pulls away . that 's acceleration , the change in speed over time . acceleration is a vector quantity . it describes a rate at which an object changes velocity . like velocity , acceleration is a vector . it happens in a direction . so let 's just look at that play just one more time . `` quarterback steps back to receive the ball , five yards deep in the gun . '' vector ! `` he takes a snap , drops three steps , he plants his back foot . he 's looking for an opening . there 's a blitz coming off the edge ! he steps up to avoid the rush . '' displacement ! `` he 's got the inside receiver making a cut . he 's got a step on the linebacker . the quarterback has a beat on it . he let 's the ball go ! it 's in the air ! receiver is out in front of the defender ! '' velocity ! `` he 's got it beat ! he 's out in front , racing for the ball ! it 's coming down ! he cradles it at the fifteen , he 's at the ten , five ! '' acceleration ! `` touchdown ! unbelievable play ! that was a great play as time expired , resulting in the touchdown and ultimately the win and pure effort . '' and pure science .
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they 're both traveling in a forward direction , so their velocity is also positive . you ca n't go from resting to your peak speed immediately . you 've got to build up to it .
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what principle describes why you ca n't go from resting to your peak speed immediately ?
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most people recognize his name and know that he is famous for having said something , but considering the long-lasting impact his teachings have had on the world , very few people know who confucius really was , what he really said , and why . amid the chaos of 6th century bce china , where warring states fought endlessly among themselves for supremacy , and rulers were frequently assassinated , sometimes by their own relatives , confucius exemplified benevolence and integrity , and through his teaching , became one of china 's greatest philosophers . born to a nobleman but raised in poverty from a very young age following the untimely death of his father , confucius developed what would become a lifelong sympathy for the suffering of the common people . barely supporting his mother and disabled brother as a herder and account keeper at a granary , and with other odd jobs , it was only with the help of a wealthy friend that confucius was able to study at the royal archives , where his world view would be formed . though the ancient texts there were regarded by some as irrelevant relics of the past , confucius was inspired by them . through study and reflection , confucius came to believe that human character is formed in the family and by education in ritual , literature , and history . a person cultivated in this way works to help others , guiding them by moral inspiration rather than brute force . to put his philosophy into practice , confucius became an advisor to the ruler of his home state of lu . but after another state sent lu 's ruler a troop of dancing girls as a present and the ruler ignored his duties while enjoying the girls in private , confucius resigned in disgust . he then spent the next few years traveling from state to state , trying to find a worthy ruler to serve , while holding fast to his principles . it was n't easy . in accordance with his philosophy , and contrary to the practice of the time , confucius dissuaded rulers from relying on harsh punishments and military power to govern their lands because he believed that a good ruler inspires others to spontaneously follow him by virtue of his ethical charisma . confucius also believed that because the love and respect we learn in the family are fundamental to all other virtues , personal duties to family sometimes supersede obligations to the state . so when one duke bragged that his subjects were so upright that a son testified against his own father when his father stole a sheep , confucius informed the duke that genuinely upright fathers and sons protected one another . during his travels , confucius almost starved , he was briefly imprisoned , and his life was threatened at several points . but he was not bitter . confucius had faith that heaven had a plan for the world , and he taught that a virtuous person could always find joy in learning and music . failing to find the ruler he sought , confucius returned to lu and became a teacher and philosopher so influential , that he helped shaped chinese culture and we recognize his name worldwide , even today . for the disciples of confucius , he was the living embodiment of a sage who leads others through his virtue , and they recorded his sayings , which eventually were edited into a book we know in english as `` the analects . '' today , millions of people worldwide adhere to the principles of confucianism , and though the precise meaning of his words has been debated for millennia , when asked to summarize his teachings in a single phrase , confucius himself said , `` do not inflict upon others that which you yourself would not want . '' 2,500 years later , it 's still sage advice .
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in accordance with his philosophy , and contrary to the practice of the time , confucius dissuaded rulers from relying on harsh punishments and military power to govern their lands because he believed that a good ruler inspires others to spontaneously follow him by virtue of his ethical charisma . confucius also believed that because the love and respect we learn in the family are fundamental to all other virtues , personal duties to family sometimes supersede obligations to the state . so when one duke bragged that his subjects were so upright that a son testified against his own father when his father stole a sheep , confucius informed the duke that genuinely upright fathers and sons protected one another .
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describe confucius 's views on the importance of the family .
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in 1956 , during a diplomatic reception in moscow , soviet leader nikita khrushchev told western bloc ambassadors , `` my vas pokhoronim ! '' his interpreter rendered that into english as , `` we will bury you ! '' this statement sent shockwaves through the western world , heightening the tension between the soviet union and the us who were in the thick of the cold war . some believe this incident alone set east/west relations back a decade . as it turns out , khrushchev 's remark was translated a bit too literally . given the context , his words should have been rendered as , `` we will live to see you buried , '' meaning that communism would outlast capitalism , a less threatening comment . though the intended meaning was eventually clarified , the initial impact of khrushchev 's apparent words put the world on a path that could have led to nuclear armageddon . so now , given the complexities of language and cultural exchange , how does this sort of thing not happen all the time ? much of the answer lies with the skill and training of interpreters to overcome language barriers . for most of history , interpretation was mainly done consecutively , with speakers and interpreters making pauses to allow each other to speak . but after the advent of radio technology , a new simultaneous interpretations system was developed in the wake of world war ii . in the simultaneous mode interpreters instantaneously translate a speaker 's words into a microphone while he speaks . without pauses , those in the audience can choose the language in which they want to follow . on the surface , it all looks seamless , but behind the scenes , human interpreters work incessantly to ensure every idea gets across as intended . and that is no easy task . it takes about two years of training for already fluent bilingual professionals to expand their vocabulary and master the skills necessary to become a conference interpreter . to get used to the unnatural task of speaking while they listen , students shadow speakers and repeat their every word exactly as heard in the same language . in time , they begin to paraphrase what is said , making stylistic adjustments as they go . at some point , a second language is introduced . practicing in this way creates new neural pathways in the interpreter 's brain , and the constant effort of reformulation gradually becomes second nature . over time and through much hard work , the interpreter masters a vast array of tricks to keep up with speed , deal with challenging terminology , and handle a multitude of foreign accents . they may resort to acronyms to shorten long names , choose generic terms over specific , or refer to slides and other visual aides . they can even leave a term in the original language , while they search for the most accurate equivalent . interpreters are also skilled at keeping aplomb in the face of chaos . remember , they have no control over who is going to say what , or how articulate the speaker will sound . a curveball can be thrown at any time . also , they often perform to thousands of people and in very intimidating settings , like the un general assembly . to keep their emotions in check , they carefully prepare for an assignment , building glossaries in advance , reading voraciously about the subject matter , and reviewing previous talks on the topic . finally , interpreters work in pairs . while one colleague is busy translating incoming speeches in real time , the other gives support by locating documents , looking up words , and tracking down pertinent information . because simultaneous interpretation requires intense concentration , every 30 minutes , the pair switches roles . success is heavily dependent on skillful collaboration . language is complex , and when abstract or nuanced concepts get lost in translation , the consequences may be catastrophic . as margaret atwood famously noted , `` war is what happens when language fails . '' conference interpreters of all people are aware of that and work diligently behind the scenes to make sure it never does .
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much of the answer lies with the skill and training of interpreters to overcome language barriers . for most of history , interpretation was mainly done consecutively , with speakers and interpreters making pauses to allow each other to speak . but after the advent of radio technology , a new simultaneous interpretations system was developed in the wake of world war ii .
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for most of history , interpretation was done consecutively rather than simultaneously . what are the differences between these two methods of interpreting ?
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many people in the united states and latin america have grown up celebrating the anniversary of christopher columbus 's voyage , but was he an intrepid explorer who brought two worlds together or a ruthless exploiter who brought colonialism and slavery ? and did he even discover america at all ? it 's time to put columbus on the stand in history vs. christopher columbus . `` order , order in the court . wait , am i even supposed to be at work today ? '' cough `` yes , your honor . from 1792 , columbus day was celebrated in many parts of the united states on october 12th , the actual anniversary date . but although it was declared an official holiday in 1934 , individual states are n't required to observe it . only 23 states close public services , and more states are moving away from it completely . '' cough `` what a pity . in the 70s , we even moved it to the second monday in october so people could get a nice three-day weekend , but i guess you folks just hate celebrations . '' `` uh , what are we celebrating again ? '' `` come on , your honor , we all learned it in school . christopher columbus convinced the king of spain to send him on a mission to find a better trade route to india , not by going east over land but sailing west around the globe . everyone said it was crazy because they still thought the world was flat , but he knew better . and when in 1492 he sailed the ocean blue , he found something better than india : a whole new continent . '' `` what rubbish . first of all , educated people knew the world was round since aristotle . secondly , columbus did n't discover anything . there were already people living here for millennia . and he was n't even the first european to visit . the norse had settled newfoundland almost 500 years before . '' `` you do n't say , so how come we 're not all wearing those cow helmets ? '' `` actually , they did n't really wear those either . '' cough `` who cares what some vikings did way back when ? those settlements did n't last , but columbus 's did . and the news he brought back to europe spread far and wide , inspiring all the explorers and settlers who came after . without him , none of us would be here today . '' `` and because of him , millions of native americans are n't here today . do you know what columbus did in the colonies he founded ? he took the very first natives he met prisoner and wrote in his journal about how easily he could conquer and enslave all of them . '' `` oh , come on . everyone was fighting each other back then . did n't the natives even tell columbus about other tribes raiding and taking captives ? '' `` yes , but tribal warfare was sporadic and limited . it certainly did n't wipe out 90 % of the population . '' `` hmm . why is celebrating this columbus so important to you , anyway ? '' `` your honor , columbus 's voyage was an inspiration to struggling people all across europe , symbolizing freedom and new beginnings . and his discovery gave our grandparents and great-grandparents the chance to come here and build better lives for their children . do n't we deserve a hero to remind everyone that our country was build on the struggles of immigrants ? '' `` and what about the struggles of native americans who were nearly wiped out and forced into reservations and whose descendants still suffer from poverty and discrimination ? how can you make a hero out of a man who caused so much suffering ? '' `` that 's history . you ca n't judge a guy in the 15th century by modern standards . people back then even thought spreading christianity and civilization across the world was a moral duty . '' `` actually , he was pretty bad , even by old standards . while governing hispaniola , he tortured and mutilated natives who did n't bring him enough gold and sold girls as young as nine into sexual slavery , and he was brutal even to the other colonists he ruled , to the point that he was removed from power and thrown in jail . when the missionary , bartolomé de las casas , visited the island , he wrote , 'from 1494 to 1508 , over 3,000,000 people had perished from war , slavery and the mines . who in future generations will believe this ? ' '' `` well , i 'm not sure i believe those numbers . '' `` say , are n't there other ways the holiday is celebrated ? '' `` in some latin american countries , they celebrate the same date under different names , such as día de la raza . in these places , it 's more a celebration of the native and mixed cultures that survived through the colonial period . some places in the u.s. have also renamed the holiday , as native american day or indigenous people 's day and changed the celebrations accordingly . '' `` so , why not just change the name if it 's such a problem ? '' `` because it 's tradition . ordinary people need their heroes and their founding myths . ca n't we just keep celebrating the way we 've been doing for a century , without having to delve into all this serious research ? it 's not like anyone is actually celebrating genocide . '' `` traditions change , and the way we choose to keep them alive says a lot about our values . '' `` well , it looks like giving tired judges a day off is n't one of those values , anyway . '' traditions and holidays are important to all cultures , but a hero in one era may become a villain in the next as our historical knowledge expands and our values evolve . and deciding what these traditions should mean today is a major part of putting history on trial .
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cough `` yes , your honor . from 1792 , columbus day was celebrated in many parts of the united states on october 12th , the actual anniversary date . but although it was declared an official holiday in 1934 , individual states are n't required to observe it .
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what is the official status of columbus day in the united states ?
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the stereotype that men are smarter than women has a long history , but in the battle of the sexes , who actually has the superior intellect when it comes down to it ? are boys smarter than girls ? early studies show that male brains are 8 to 13 percent larger in volume than female brains , however this has been since attributed to differences in body size . women 's brains have more gyrofication or brain folding , and as a result , a greater cortical surface area . besides , bigger is n't always better . sperm whales , elephants and dolphins all have larger brains than humans , and while they are smart , their cognitive abilities are less than our own . there are other structural differences , though , like males having more connections within hemispheres , while women have more connections between hemispheres . but overall , mri brain imaging shows significant overlap in the physical structure between the sexes . after studying 14 hundred brains and comparing the sexes , researchers found that mostly all men and woman show a mosaic of female and male typical structures in the brain . this study also evaluted gender stereotypical behaviours . like how video games are often considered male behaviour while scrapbooking is female and the results found that 0.1 % of test subjects displayed only male or only female typical behaviours . tests on intelligence find similar results with major iq studies showing neglible , or no sex differences in general intelligence but do show women having stronger verbal abilities while men show stronger visual-spatial abilities . interestingly , studies show more male variance in tests with their scores being both the worst and the best . one meta analysis of 22 studies did fiund men to be 3.3 to 5.5 iq points above women but this study has been called into question by academics who found the methodology flawed . in academic performance of language , math and science , women consistently received better grade in 70 % of nations . but on sat testing in the u.s. men scored 33 points higher in math and science . other tests like the program for international student assessment showed both sexes performing equally in several countries with girls performing better in some like iceland suggesting cultural and environmental differences and not necessarily biological differences at play . but research has found that stereotypes about womens performance actually impact how well they do . when told that a particular math test had significant gender differences , women performed significantly worse than their male peers . while women who were told there was no difference , scored the same . this phenomenom is known as the stereotype threat . even google search data shows that parents 2.5 times more likely to search is my son gifted than is my daughter gifted ? despite 11 % more girls in gifted programs in america . and girls pick up on these bias as early as 6 years old . when told a story at age 5 about a person who is really really smart both boys and girls associate intelligence with there own gender but by age 6 both girls and boys picked a male character as the smartest . in a similar experiment kids were asked if they wanted to play a game for people who are really really smart and again at age 5 both sexes wanted to play but by age 6 , girls had decided these games were n't for them . and though women do strive to work in stem fields studies show they face barriers . in a double blind study science faculty from research universities rated applications for a lab manager position . what they did n't know is that the applications were randomly assigned either male or female names . as a result , faculty perceived the male applicant names to be significantly more competent , hireable and deserving of mentoring even though the applications with female names were identical . males were also offered higher starting salaries , an average of 30,000 versus the females 26,000 . though these studies produce a sobering reality research does point to growing equality between the sexes with passing decades and education and in spite of these barriers women continue to contribute to our collective scientific knowledge . rosalind franklin allowed us to understand our own dna , katherine johnson helped apollo 11 land on the moon and this year maryam mirzakhani is the first women to win a nobel prize for mathematics . fellow mathematician izabella laba said `` mirzakhan 's selection does exactly nothing to convince me that women are capable of doing mathematical research at the same level of men . i have never had any doubt about that in the first place.. what i take from it instead is that we as a society , men and women alike , are becoming better at encouraging and nurturing mathematical talent in women , and more capable of reconizing excellence in women 's work . '' to learn more we asked the women at asap science to speak personally about their experiences growing up and give insight about how they navigate the societal pressures of being a woman . click on the screen or the link in the description to check out that video and subscribe for more weekly science videos every thursday .
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like how video games are often considered male behaviour while scrapbooking is female and the results found that 0.1 % of test subjects displayed only male or only female typical behaviours . tests on intelligence find similar results with major iq studies showing neglible , or no sex differences in general intelligence but do show women having stronger verbal abilities while men show stronger visual-spatial abilities . interestingly , studies show more male variance in tests with their scores being both the worst and the best .
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iq tests have found that women have better _____ abilities and men have had better _____ abilities .
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emily dickinson said over a century ago that `` there is no frigate like a book to take us lands away ... '' and it 's true . when we pick up a book , turn on the tv , or watch a movie , we 're carried away down the currents of story into a world of imagination . and when we land , on a shore that is both new and familiar , something strange happens . stepping onto the shore , we 're changed . we do n't retrace the footsteps of the authors or characters we followed here . no ; instead , we walk a mile in their shoes . researchers in psychology , neuroscience , child development and biology are finally starting to gain quantifiable scientific evidence , showing what writers and readers have always known : that stories have a unique ability to change a person 's point of view . scholars are discovering evidence that stories shape culture , and that much of what we believe about life comes not from fact , but from fiction - that our ideas of class , marriage and even gender are relatively new , and that many ideologies which held fast for centuries were revised within the 18th century , and redrafted in the pages of the early novel . imagine a world where class , and not hard work , decides a person 's worth ; a world where women are simply men 's more untamed copy ; a world where marriage for love is a novel notion . well , that was the world in which samuel richardson 's `` pamela '' first appeared . richardson 's love story starred a poor , serving-class heroine , who is both more superior and smarter than her upper-class suitor . the book , challenging a slew of traditions , caused quite a ruckus . there was more press for `` pamela '' than for parliament . it spawned intense debate and several counter-novels . still , for all those who could n't accept `` pamela , '' others were eager for this new fictional world . this best seller and all its literary heirs - `` pride and prejudice , '' `` jane eyre , '' and yes , even `` twilight '' - have continuously shared the same tale and taught similar lessons , which are now conventional and commonplace . similarly , novels have helped shape the minds of thought leaders across history . some scholars say that darwin 's theory of evolution is highly indebted to the plots he read and loved . his theory privileges intelligence , swiftness , and adaptability to change - all core characteristics in a hero . whether you 're reading `` harry potter '' or `` great expectations , '' you 're reading the kind of plot that inspired darwin . yet , recent studies show that his theory might not be the whole story . our sense of being a hero - one man or one woman or even one species taking on the challenges of the world - might be wrong . instead of being hardwired for competition for being the solitary heroes in our own story , we might instead be members of a shared quest . more hobbit than harry . sometimes , of course , the shoes we 've been walking in can get plain worn out . after all , we have n't walked just one mile in jane austen 's or mark twain 's shoes - we 've walked about 100 trillion miles in them . this is n't to say that we ca n't read and enjoy the classics ; we should travel with dickens , let pip teach us what to expect from ourselves , have a talk with austen and elizabeth about our prides and prejudices . we should float with twain down the mississippi , and have jim show us what it means to be good . but on our journey , we should also keep in mind that the terrain has changed . we 'll start shopping around for boots that were made for walking into a new era . take , for instance , katniss everdeen and her battle with the capitol . can `` hunger games '' lead us into thinking about capitalism in a new way ? can it teach us a lesson about why the individual should not put herself before the group ? will `` uglies '' reflect the dangers of pursuing a perfect body and letting the media define what is beautiful ? will `` seekers '' trod a path beyond global warming ? will the life-and-death struggles of toklo , kallik , lusa and the other bears chart a course for understanding animals and our place in their world ? only the future will tell which stories will engage our imagination , which tales of make-believe we 'll make tomorrow . but the good news is this : there are new stories to venture in every day , new tales that promise to influence , to create and to spark change - stories that you might even write yourself . so i guess the final question is this : what story will you try on next ?
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his theory privileges intelligence , swiftness , and adaptability to change - all core characteristics in a hero . whether you 're reading `` harry potter '' or `` great expectations , '' you 're reading the kind of plot that inspired darwin . yet , recent studies show that his theory might not be the whole story .
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do you think reading engages the imagination ? how ? are you more inclined to read fiction or non-fiction ? why ?
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and you can see that the phosphorus has oxidized in the air and it ’ s taken some of the paper with it to generate a nice ‘ p ’ for phosphorus . so this is a sample of my favourite element , this is phosphorus . phosphorus is a very , very reactive element , especially this type of phosphorus which is white phosphorus . phosphorus itself , elemental phosphorus , exists as a number of different allotropes , so a bit like carbon with diamond and graphite , and here we have one of these allotropes ; it ’ s white phosphorus . it exists as discrete molecules of four phosphorus atoms connected like a pyramid , and those four phosphorus atoms are really strained , really reactive and they want to really react with oxygen as quick as they can . this is the sort that is used in phosphorus bombs . it burns very easily and gives a very intense white light out of it . so instantaneously you can see that fantastic oxidation reaction as the phosphorus reacts with the molecular oxygen in the gas inside the flask . you can put it out quite easily by putting water on it , provided that it hasn ’ t got too hot and the water will just evaporate . very reactive form the other allotropes , black and red phosphorus , are not as reactive and are much , much easier for us to handle . then there ’ s red phosphorus which is very much less reactive which is what is used in matches . it is used to make the heads of so-called ‘ non-safety ’ matches , which are the ones you can strike on any sort of material , on bricks and so on , and they tend to be this rather red colour here . so the phosphorus , you ’ ll notice , that it ’ s stored under water , and it ’ s stored under water to keep the oxygen and the atmosphere away because it reacts very vigorously and can burn , hence the signs , it ’ s very , very flammable . it ’ s so flammable in fact that it burns just with the heat of the skin . so you can see a number of scars across my hands , these are all from playing with phosphorus and doing reactions and experiments with phosphorus . phosphorus is a very important point inside your body . some of you may have read aldous huxley ’ s book called ‘ brave new world ’ , which when people died they were sent to the phosphorus reclamation plant . and each average size person contains somewhat over a pound of phosphorus inside their bodies , and nowadays people can use magnetic resonance imaging to look and see how the phosphorus is used inside the body . so i ’ ve taken a small sample of my white phosphorus and i ’ ve dissolved it in an organic solvent which is carbon disulphide , because the p4 is molecular and it dissolves really quite nicely in this molecular solvent . so now what we are going to do is we ’ re going to go outside and we ’ re going to put this on a piece of filter paper and then let the carbon disulphide evaporate so we can see the reaction of the phosphorus with the oxygen and the paper . and the average person produces inside their body about 70 kilos a day of a molecule called atp , adenosine triphosphate , which is the energy producing molecule inside the body . now you don ’ t keep 70 kilos inside you , or you would explode , but you ’ re using it up all the time but in the course of the day you synthesise nearly 70 kilos of this molecule . so as the carbon disulphide evaporates from the paper , well there ’ s a couple of drips . and you can see that the phosphorus has oxidized in the air and it ’ s taken some of the paper with it to generate a nice ‘ p ’ for phosphorus .
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so this is a sample of my favourite element , this is phosphorus . phosphorus is a very , very reactive element , especially this type of phosphorus which is white phosphorus . phosphorus itself , elemental phosphorus , exists as a number of different allotropes , so a bit like carbon with diamond and graphite , and here we have one of these allotropes ; it ’ s white phosphorus .
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what is the molecular formula of the reactive allotrope white phosphorus ?
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are you sleeping restlessly , feeling irritable or moody , forgetting little things , and feeling overwhelmed and isolated ? do n't worry . we 've all been there . you 're probably just stressed out . stress is n't always a bad thing . it can be handy for a burst of extra energy and focus , like when you 're playing a competitive sport , or have to speak in public . but when its continuous , the kind most of us face day in and day out , it actually begins to change your brain . chronic stress , like being overworked or having arguments at home , can affect brain size , its structure , and how it functions , right down to the level of your genes . stress begins with something called the hypothalamus pituitary adrenal axis , a series of interactions between endocrine glands in the brain and on the kidney , which controls your body 's reaction to stress . when your brain detects a stressful situation , your hpa axis is instantly activated and releases a hormone called cortisol , which primes your body for instant action . but high levels of cortisol over long periods of time wreak havoc on your brain . for example , chronic stress increases the activity level and number of neural connections in the amygdala , your brain 's fear center . and as levels of cortisol rise , electric signals in your hippocampus , the part of the brain associated with learning , memories , and stress control , deteriorate . the hippocampus also inhibits the activity of the hpa axis , so when it weakens , so does your ability to control your stress . that 's not all , though . cortisol can literally cause your brain to shrink in size . too much of it results in the loss of synaptic connections between neurons and the shrinking of your prefrontal cortex , the part of your brain the regulates behaviors like concentration , decision-making , judgement , and social interaction . it also leads to fewer new brain cells being made in the hippocampus . this means chronic stress might make it harder for you to learn and remember things , and also set the stage for more serious mental problems , like depression and eventually alzheimer 's disease . the effects of stress may filter right down to your brain 's dna . an experiment showed that the amount of nurturing a mother rat provides its newborn baby plays a part in determining how that baby responds to stress later in life . the pups of nurturing moms turned out less sensitive to stress because their brains developed more cortisol receptors , which stick to cortisol and dampen the stress response . the pups of negligent moms had the opposite outcome , and so became more sensitive to stress throughout life . these are considered epigenetic changes , meaning that they effect which genes are expressed without directly changing the genetic code . and these changes can be reversed if the moms are swapped . but there 's a surprising result . the epigenetic changes caused by one single mother rat were passed down to many generations of rats after her . in other words , the results of these actions were inheritable . it 's not all bad news , though . there are many ways to reverse what cortisol does to your stressed brain . the most powerful weapons are exercise and meditation , which involves breathing deeply and being aware and focused on your surroundings . both of these activities decrease your stress and increase the size of the hippocampus , thereby improving your memory . so do n't feel defeated by the pressures of daily life . get in control of your stress before it takes control of you .
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you 're probably just stressed out . stress is n't always a bad thing . it can be handy for a burst of extra energy and focus , like when you 're playing a competitive sport , or have to speak in public .
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can stress ever be a good thing ? explain .
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translator : ido dekkers reviewer : ariana bleau lugo so what is gravity ? i bet most of you think it 's : `` what goes up , must come down ! '' is that right ? well , sorta , but not really . technically , the law of gravity is an equation . it is : f = g x m1 x m2 / r^2 , where g is the universal gravitational constant , m1 and m2 are the masses of the two objects , and r is the distance between them squared . that was easy , right ? probably not . what does this actually mean ? well it means that - well , everything is attracted to everything else . what i mean by that is if you have two objects , any two objects , they are attracted to each other . ok. let 's try and wrap our minds around this . what happens when you drop a rock off a cliff ? it falls to the earth . right ? well , yes , but something else happens . you see , the law of gravity says that both objects , the rock and the earth , are attracted to each other . this means that the rock falls towards the earth , and the earth falls towards the rock . wait a second - you mean to tell me that if - the earth falls up to meet the rock ? yes , that 's exactly what i 'm saying . and the reason you do n't see the earth fall up to meet the rock is because the objects move towards each other proportionate to their respective masses . the earth is much much much more massive than the rock , so it moves a very very small distance , and the rock is much less massive , so it moves farther with respect to the earth . maybe a better way to understand gravity is to take two teenagers in spacesuits , and place them far out in space - away from all the planets and the stars . it turns out they will be attracted to each other . i 'm not talking about that kind of attraction . see , they have mass , and since they have mass , they will move towards each other . they are attracted to each other . maybe one more thing might help . have you ever played with two magnets ? you know , the magnets with the north and the south poles ? when you take the magnets and put them closer to each other , they move together . they are attracted to each other . and the closer they are , the stronger the attraction . think of the mass of the object like the strength of a magnet and the distance between the objects like the distance between the two magnets . now understand , i 'm not saying that gravity and magnetism are the same , they just behave in a similar way . let 's think of one other thing - astronauts . you know , astronauts , they weigh less on the moon than on the earth . why is that ? well you see , the moon is less massive than the earth . therefore it has a smaller gravitational pull on the astronaut . it 's like the moon is a weaker magnet . they are n't as attracted to each other . distance also plays a role . think back to playing with a magnet . the pull of the magnets towards each other are stronger when they are closer together . the same is true of gravity . for example , the sun is the most massive object near the earth . it dictates most of the gravitational forces in our solar system . it is very very massive . but it is relatively far away , so even though the sun is a much stronger magnet , so to speak , it is a long ways away . therefore the attraction is n't as strong . so let 's look back at that law of gravity . the equation : f = g x m1 x m2 / r ^2 . you see the force of gravity is equal to a number . that 's that universal gravitational constant g times the mass of object one , times the mass of object two . think of m1 being the mass of the sun and m2 being the mass of the earth . and then we divide by the distance between them squared . this determines the force of attraction between the sun and earth . you could just as easily plug in your mass and the earth 's mass and the distance between you and the center of the earth , and find out how much you are attracted to the earth , and the earth attracted to you . so , what 's gravity ? everything is attracted to everything else . everything . oh , one last thing , just to make you wonder . what causes gravity ? why are two objects with mass attracted to each other ? well , the answer is - we do n't know . the cause of gravity remains a mystery to scientists . we do n't really know conclusively what causes gravity . it is one of the great mysteries of science .
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let 's think of one other thing - astronauts . you know , astronauts , they weigh less on the moon than on the earth . why is that ?
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why do astronauts weigh less on the moon than they do on the earth ?
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he was one of the most influential figures of the 20th century , forever changing the course of one of the world 's largest countries . but was he a hero who toppled an oppressive tyranny or a villain who replaced it with another ? it 's time to put lenin on the stand in history vs. lenin . `` order , order , hmm . now , was n't it your fault that the band broke up ? '' `` your honor , this is vladimir ilyich ulyanov , aka lenin , the rabblerouser who helped overthrow the russian tsar nicholas ii in 1917 and founded the soviet union , one of the worst dictatorships of the 20th century . '' `` ohh . '' `` the tsar was a bloody tyrant under whom the masses toiled in slavery . '' `` this is rubbish . serfdom had already been abolished in 1861 . '' `` and replaced by something worse . the factory bosses treated the people far worse than their former feudal landlords . and unlike the landlords , they were always there . russian workers toiled for eleven hours a day and were the lowest paid in all of europe . '' `` but tsar nicholas made laws to protect the workers . '' `` he reluctantly did the bare minimum to avert revolution , and even there , he failed . remember what happened in 1905 after his troops fired on peaceful petitioners ? '' `` yes , and the tsar ended the rebellion by introducing a constitution and an elected parliament , the duma . '' `` while retaining absolute power and dissolving them whenever he wanted . '' `` perhaps there would 've been more reforms in due time if radicals , like lenin , were n't always stirring up trouble . '' `` your honor , lenin had seen his older brother aleksandr executed by the previous tsar for revolutionary activity , and even after the reforms , nicholas continued the same mass repression and executions , as well as the unpopular involvement in world war i , that cost russia so many lives and resources . '' `` hm , this tsar does n't sound like such a capital fellow . '' `` your honor , maybe nicholas ii did doom himself with bad decisions , but lenin deserves no credit for this . when the february 1917 uprisings finally forced the tsar to abdicate , lenin was still exiled in switzerland . '' `` hm , so who came to power ? '' `` the duma formed a provisional government , led by alexander kerensky , an incompetent bourgeois failure . he even launched another failed offensive in the war , where russia had already lost so much , instead of ending it like the people wanted . '' `` it was a constitutional social democratic government , the most progressive of its time . and it could have succeeded eventually if lenin had n't returned in april , sent by the germans to undermine the russian war effort and instigate riots . '' `` such slander ! the july days were a spontaneous and justified reaction against the government 's failures . and kerensky showed his true colors when he blamed lenin and arrested and outlawed his bolshevik party , forcing him to flee into exile again . some democracy ! it 's a good thing the government collapsed under their own incompetence and greed when they tried to stage a military coup then had to ask the bolsheviks for help when it backfired . after that , all lenin had to do was return in october and take charge . the government was peacefully overthrown overnight . '' `` but what the bolsheviks did after gaining power was n't very peaceful . how many people did they execute without trial ? and was it really necessary to murder the tsar 's entire family , even the children ? '' `` russia was being attacked by foreign imperialists , trying to restore the tsar . any royal heir that was rescued would be recognized as ruler by foreign governments . it would 've been the end of everything the people had fought so hard to achieve . besides , lenin may not have given the order . '' `` but it was not only imperialists that the bolsheviks killed . what about the purges and executions of other socialist and anarchist parties , their old allies ? what about the tambov rebellion , where peasants , resisting grain confiscation , were killed with poison gas ? or sending the army to crush the workers in kronstadt , who were demanding democratic self-management ? was this still fighting for the people ? '' `` yes ! the measures were difficult , but it was a difficult time . the new government needed to secure itself while being attacked from all sides , so that the socialist order could be established . '' `` and what good came of this socialist order ? even after the civil war was won , there were famines , repression and millions executed or sent to die in camps , while lenin 's successor stalin established a cult of personality and absolute power . '' `` that was n't the plan . lenin never cared for personal gains , even his enemies admitted that he fully believed in his cause , living modestly and working tirelessly from his student days until his too early death . he saw how power-hungry stalin was and tried to warn the party , but it was too late . '' `` and the decades of totalitarianism that followed after ? '' `` you could call it that , but it was lenin 's efforts that changed russia in a few decades from a backward and undeveloped monarchy full of illiterate peasants to a modern , industrial superpower , with one of the world 's best educated populations , unprecedented opportunities for women , and some of the most important scientific advancements of the century . life may not have been luxurious , but nearly everyone had a roof over their head and food on their plate , which few countries have achieved . '' `` but these advances could still have happened , even without lenin and the repressive regime he established . '' `` yes , and i could 've been a famous rock and roll singer . but how would i have sounded ? '' we can never be sure how things could 've unfolded if different people were in power or different decisions were made , but to avoid the mistakes of the past , we must always be willing to put historical figures on trial .
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what about the purges and executions of other socialist and anarchist parties , their old allies ? what about the tambov rebellion , where peasants , resisting grain confiscation , were killed with poison gas ? or sending the army to crush the workers in kronstadt , who were demanding democratic self-management ?
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who were the main participants in the kronsdadt rebellion ?
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today when people complain about the state of american politics , they often mention the dominance of the democratic and republican parties , or the sharp split between red and blue states . but while it may seem like both of these things have been around forever , the situation looked quite different in 1850 , with the republican party not yet existing , and support for the dominant democrats and whigs cutting across geographic divides . the collapse of this second party system was at the center of increasing regional tensions that would lead to the birth of the republican party , the rise of abraham lincoln as its leader , and a civil war that would claim over half a million lives . and if this collapse could be blamed on a single event , it would be the kansas-nebraska act of 1854 . the story starts with the missouri compromise of 1820 . to balance the number of slave states and free states in the union , it allowed slavery in the newly admitted state of missouri , while making it off limits in the remaining federally administered louisiana territory . but compromises tend to last only as long as they 're convenient , and by the early 1850s , a tenacious democratic senator from illionis named stephen a. douglas found its terms very inconvenient . as an advocate of western expansion , he promoted constructing a transcontinental railroad across the northern plains with an eastern terminus in chicago , where he happened to own real estate . for his proposal to succeed , douglas felt that the territories through which the railroad passed , would have to be formally organized , which required the support of southern politicians . he was also a believer in popular sovereignty , arguing that the status of slavery in a territory should be decided by its residents rather than congress . so douglas introduced a bill designed to kill two birds with one stone . it would divide the large chunk of incorporated land into two new organized territories : nebraska and kansas , each of which would be open to slavery if the population voted to allow it . while douglas and his southern supporters tried to frame the bill as protecting the political rights of settlers , horrified northerners recognized it as repealing the 34-year-old missouri compromise and feared that its supporters ' ultimate goal was to extend slavery to the entire nation . congress was able to pass the kansas-nebraska act , but at the huge cost of bitterly dividing the nation , with 91 % of the opposition coming from northerners . in the house of representatives , politicians traded insults and brandished weapons until a sargent at arms restored order . president pierce signed the bill into law amidst a storm of protest , while georgia 's alexander stephens , future confederate vice president , hailed the act 's passage as , `` glory enough for one day . '' the new york tribune reported , `` the unanimous sentiment of the north is indignant resistance . '' douglas even admitted that he could travel from washington d.c. to chicago by the light of his own burning effigies . the political consequences of the kansas-nebraska act were stunning . previously , both whigs and democrats had included northern and southern lawmakers united around various issues , but now slavery became a dividing factor that could not be ignored . congressmen from both parties spoke out against the act , including an illinois whig named abraham lincoln , denouncing `` the monstrous injustice of slavery '' in an 1854 speech . by this time the whigs had all but ceased to exist , irreparably split between their northern and southern factions . in the same year , the new republican party was founded by the anti-slavery elements from both existing parties . although lincoln still ran for senate as a whig in 1854 , he was an early supporter of the new party , and helped to recruit others to its cause . meanwhile the democratic party was shaken when events in the newly formed kansas territory revealed the violent consequences of popular sovereignty . advertisements appeared across the north imploring people to emigrate to kansas to stem the advance of slavery . the south answered with border ruffians , pro-slavery missourians who crossed state lines to vote in fraudulent elections and raid anti-slavery settlements . one northern abolitionist , john brown , became notorious following the pottawatomie massacre of 1856 when he and his sons hacked to death five pro-slavery farmers with broad swords . in the end , more than 50 people died in bleeding kansas . while nominally still a national party , douglas 's democrats were increasingly divided along sectional lines , and many northern members left to join the republicans . abraham lincoln finally took up the republican party banner in 1856 and never looked back . that year , john c. fremont , the first republican presidential candidate , lost to democrat , james buchanan , but garnered 33 % of the popular vote all from northern states . two years later , lincoln challenged douglas for his illinois senate seat , and although he lost that contest , it elevated his status among republicans . lincoln would finally be vindicated in 1860 , when he was elected president of the united states , defeating in his own home state , a certain northern democrat , who was finally undone by the disastrous aftermath of the law he had masterminded . americans today continue to debate whether the civil war was inevitable , but there is no doubt that the kansas-nebraska act made the ghastly conflict much more likely . and for that reason , it should be remembered as one of the most consequential pieces of legislation in american history .
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in the end , more than 50 people died in bleeding kansas . while nominally still a national party , douglas 's democrats were increasingly divided along sectional lines , and many northern members left to join the republicans . abraham lincoln finally took up the republican party banner in 1856 and never looked back .
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when and how did other developments of the 1850s heighten sectional tensions ?
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the discovery of the structure of dna was one of the most important scientific achievements in the last century , in human history , in fact . the now-famous double helix is almost synonymous with watson and crick , two of the scientists who won the nobel prize for figuring it out . but there 's another name you may know , too , rosalind franklin . you may have heard that her data supported watson and crick 's brilliant idea , or that she was a plain-dressing , belligerent scientist , which is how watson actually described her in `` the double helix . '' but thanks to franklin 's biographers , who investigated her life and interviewed many people close to her , we now know that that account is far from true , and her scientific contributions have been vastly underplayed . let 's hear the real story . rosalind elsie franklin was born in london in 1920 . she wanted to be a scientist ever since she was a teenager , which was n't a common or easy career path for girls at that time . but she excelled at science anyway . she won a scholarship to cambridge to study chemistry , where she earned her ph.d. , and she later conducted research on the structure of coal that led to better gas masks for the british during world war ii . in 1951 , she joined king 's college to use x-ray techniques to study the structure of dna , then one of the hottest topics in science . franklin upgraded the x-ray lab and got to work shining high-energy x-rays on tiny , wet crystals of dna . but the acadmemic culture at the time was n't very friendly to women , and franklin was isolated from her colleagues . she clashed with maurice wilkins , a labmate who assumed franklin had been hired as his assistant . but franklin kept working , and in 1952 , she obtained photo 51 , the most famous x-ray image of dna . just getting the image took 100 hours , the calculations necessary to analyze it would take a year . meanwhile , the american biologist james watson and the british physicist francis crick were also working on finding dna 's structure . without franklin 's knowledge , wilkins took photo 51 and showed it to watson and crick . instead of calculating the exact position of every atom , they did a quick analysis of franklin 's data and used that to build a few potential structures . eventually , they arrived at the right one . dna is made of two helicoidal strands , one opposite the other with bases in the center like rungs of a ladder . watson and crick published their model in april 1953 . meanwhile , franklin had finished her calculations , come to the same conclusion , and submitted her own manuscript . the journal published the manuscripts together , but put franklin 's last , making it look like her experiments just confirmed watson and crick 's breakthrough instead of inspiring it . but franklin had already stopped working on dna and died of cancer in 1958 , never knowing that watson and crick had seen her photographs . watson , crick , and wilkins won the nobel prize in 1962 for their work on dna . it 's often said that franklin would have been recognized by a nobel prize if only they could be awarded posthumously . and , in fact , it 's possible she could have won twice . her work on the structure of viruses led to a nobel for a colleague in 1982 . it 's time to tell the story of a brave woman who fought sexism in science , and whose work revolutionized medicine , biology , and agriculture . it 's time to honor rosalind elsie franklin , the unsung mother of the double helix .
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the now-famous double helix is almost synonymous with watson and crick , two of the scientists who won the nobel prize for figuring it out . but there 's another name you may know , too , rosalind franklin . you may have heard that her data supported watson and crick 's brilliant idea , or that she was a plain-dressing , belligerent scientist , which is how watson actually described her in `` the double helix . ''
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what was franklin ’ s profession ?
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how high can you count on your fingers ? it seems like a question with an obvious answer . after all , most of us have ten fingers , or to be more precise , eight fingers and two thumbs . this gives us a total of ten digits on our two hands , which we use to count to ten . it 's no coincidence that the ten symbols we use in our modern numbering system are called digits as well . but that 's not the only way to count . in some places , it 's customary to go up to twelve on just one hand . how ? well , each finger is divided into three sections , and we have a natural pointer to indicate each one , the thumb . that gives us an easy to way to count to twelve on one hand . and if we want to count higher , we can use the digits on our other hand to keep track of each time we get to twelve , up to five groups of twelve , or 60 . better yet , let 's use the sections on the second hand to count twelve groups of twelve , up to 144 . that 's a pretty big improvement , but we can go higher by finding more countable parts on each hand . for example , each finger has three sections and three creases for a total of six things to count . now we 're up to 24 on each hand , and using our other hand to mark groups of 24 gets us all the way to 576 . can we go any higher ? it looks like we 've reached the limit of how many different finger parts we can count with any precision . so let 's think of something different . one of our greatest mathematical inventions is the system of positional notation , where the placement of symbols allows for different magnitudes of value , as in the number 999 . even though the same symbol is used three times , each position indicates a different order of magnitude . so we can use positional value on our fingers to beat our previous record . let 's forget about finger sections for a moment and look at the simplest case of having just two options per finger , up and down . this wo n't allow us to represent powers of ten , but it 's perfect for the counting system that uses powers of two , otherwise known as binary . in binary , each position has double the value of the previous one , so we can assign our fingers values of one , two , four , eight , all the way up to 512 . and any positive integer , up to a certain limit , can be expressed as a sum of these numbers . for example , the number seven is 4+2+1 . so we can represent it by having just these three fingers raised . meanwhile , 250 is 128+64+32+16+8+2 . how high an we go now ? that would be the number with all ten fingers raised , or 1,023 . is it possible to go even higher ? it depends on how dexterous you feel . if you can bend each finger just halfway , that gives us three different states - down , half bent , and raised . now , we can count using a base-three positional system , up to 59,048 . and if you can bend your fingers into four different states or more , you can get even higher . that limit is up to you , and your own flexibility and ingenuity . even with our fingers in just two possible states , we 're already working pretty efficiently . in fact , our computers are based on the same principle . each microchip consists of tiny electrical switches that can be either on or off , meaning that base-two is the default way they represent numbers . and just as we can use this system to count past 1,000 using only our fingers , computers can perform billions of operations just by counting off 1 's and 0 's .
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and any positive integer , up to a certain limit , can be expressed as a sum of these numbers . for example , the number seven is 4+2+1 . so we can represent it by having just these three fingers raised .
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in our place-value system , each of the numbers 10 , 100 , 1000 , 10000 , … . uses the same two symbols , yet the sizes of the numbers represented grow ten-fold in value . in 1938 , milton sirotta , nephew of american mathematician edward kasner , coined the term “ googol ” for the number 1 followed by one hundred zeros , and the term “ googolplex ” for the number 1 followed by a googol zeros . is the estimated number of atoms in the observable universe smaller or larger than a googolplex ?
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this episode is supported by edx . termites , prairie dogs , and people are all great builders , each in their own way . and we all share one crucial problem . put a bunch of us in a closed space , breathing oxygen in and co2 out… and it doesn ’ t end well . our tallest skyscrapers and deepest mines are almost completely cut off from outside air . to keep those inside from suffocating , human engineers use giant machines to bring in fresh air and pump stale air out . termite mounds have the same problem . the largest are more than 10 meters high . on a human scale , that ’ s like a skyscraper three and a half kilometers tall ! only instead of condos and offices , it holds one big farm . the termites collect wood , which grows fungus , that the termites eat . all that fungus and the millions of termites that tend to it create a ton of co2 , which would suffocate the colony *and* their crops if it builds up . to keep the air fresh , the whole mound acts like a big lung . during the day , the sun heats the outer chambers more rapidly than the core , moving air up the outside and down the middle . during the night , this current reverses as the outer chambers lose heat to the cool night air . the whole time , co2 and oxygen are exchanged through tiny holes in the outer walls . what ’ s amazing is this is all constructed without a boss . no central architect designing the structure . just instinct and cooperation lets termites build huge ventilation engines powered by nothing but daily temperature cycles . leafcutter ants farm fungus on massive scales too . one colony in south america covered nearly 50 square meters and was home to over 8 million ants ! but unlike those towering termites , the ant labyrinth reached 8 meters underground . so how do they ventilate their agricultural city ? before we answer that , i want you to try something . take a piece of paper , hold it under your lips , and let the other end curl down . if you blow only across the top of the paper , what do you think will happen ? the force of the air hitting the paper should push it down , right ? well watch this . here ’ s what ’ s happening : air is a fluid . when i force air across the top of the paper , that stream pulls other air along , due to viscosity , which is like the friction of fluids . this leaves an area of low pressure behind , and the paper is pulled up to fill it . this is called the coandă effect . what does that have to do with ants ? check this out . when a breeze flows over a hill , the air is deflected over the top . this pulls air along too , just like when i blew over the paper , drawing air out of the ant hill along the way . the ants build lower entrances nearby , where air is drawn in to replace it , ventilating the whole colony with a little breeze . prairie dogs get the same effect from their mounds . breezes over taller hills draw air through the connected tunnel system , keeping the whole town breathing fresh . there ’ s even a tiny shrimp that uses this same system to keep fresh water flowing through its burrows . persian and egyptian architects have used similar structures to cool buildings for centuries , but tiny animals beat us to that technology by millions of years nature is full of species that build their environment to suit them , countless expert animal architects . sometimes , all you need to solve the most complex engineering problems is the awesome power of evolution , …and that ’ s a breath of fresh air . stay curious . thanks to edx , our non-profit partner for sponsoring this episode . edx.org is where you can learn for free from harvard , mit and other universities around the globe . if you liked this video , you should go check out harvard ’ s architectural imagination course . led by professor michael hays , this online course shows you how to look at architecture as an expression of culture as well as technical achievement . it brings you closer to the work of actual architects and historians through hands-on exercises and historic examples . edx.org offers university level courses in everything from artificial intelligence to leadership , data science to robots and cybersecurity . there are even courses from my alma mater , the university of texas ! edx.org puts a universe of free online learning at your fingertips . visit edx.org today and discover the courses that will keep you learning !
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no central architect designing the structure . just instinct and cooperation lets termites build huge ventilation engines powered by nothing but daily temperature cycles . leafcutter ants farm fungus on massive scales too . one colony in south america covered nearly 50 square meters and was home to over 8 million ants ! but unlike those towering termites , the ant labyrinth reached 8 meters underground .
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what natural daily phenomenon do the ants use to regulate the temperature of their anthill ?
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are you as good at things as you think you are ? how good are you at managing money ? what about reading people 's emotions ? how healthy are you compared to other people you know ? are you better than average at grammar ? knowing how competent we are and how are skill stack up against other people 's is more than a self-esteem boost . it helps us figure out when we can forge ahead on our own decisions and instincts and when we need , instead , to seek out advice . but psychological research suggests that we 're not very good at evaluating ourselves accurately . in fact , we frequently overestimate our own abilities . researchers have a name for this phenomena , the dunning-kruger effect . this effect explains why more than 100 studies have shown that people display illusory superiority . we judge ourselves as better than others to a degree that violates the laws of math . when software engineers at two companies were asked to rate their performance , 32 % of the engineers at one company and 42 % at the other put themselves in the top 5 % . in another study , 88 % of american drivers described themselves as having above average driving skills . these are n't isolated findings . on average , people tend to rate themselves better than most in disciplines ranging from health , leadership skills , ethics , and beyond . what 's particularly interesting is that those with the least ability are often the most likely to overrate their skills to the greatest extent . people measurably poor at logical reasoning , grammar , financial knowledge , math , emotional intelligence , running medical lab tests , and chess all tend to rate their expertise almost as favorably as actual experts do . so who 's most vulnerable to this delusion ? sadly , all of us because we all have pockets of incompetence we do n't recognize . but why ? when psychologists dunning and kruger first described the effect in 1999 , they argued that people lacking knowledge and skill in particular areas suffer a double curse . first , they make mistakes and reach poor decisions . but second , those same knowledge gaps also prevent them from catching their errors . in other words , poor performers lack the very expertise needed to recognize how badly they 're doing . for example , when the researchers studied participants in a college debate tournament , the bottom 25 % of teams in preliminary rounds lost nearly four out of every five matches . but they thought they were winning almost 60 % . without a strong grasp of the rules of debate , the students simply could n't recognize when or how often their arguments broke down . the dunning-kruger effect is n't a question of ego blinding us to our weaknesses . people usually do admit their deficits once they can spot them . in one study , students who had initially done badly on a logic quiz and then took a mini course on logic were quite willing to label their original performances as awful . that may be why people with a moderate amount of experience or expertise often have less confidence in their abilities . they know enough to know that there 's a lot they do n't know . meanwhile , experts tend to be aware of just how knowledgeable they are . but they often make a different mistake : they assume that everyone else is knowledgeable , too . the result is that people , whether they 're inept or highly skilled , are often caught in a bubble of inaccurate self-perception . when they 're unskilled , they ca n't see their own faults . when they 're exceptionally competent , they do n't perceive how unusual their abilities are . so if the dunning-kruger effect is invisible to those experiencing it , what can you do to find out how good you actually are at various things ? first , ask for feedback from other people , and consider it , even if it 's hard to hear . second , and more important , keep learning . the more knowledgeable we become , the less likely we are to have invisible holes in our competence . perhaps it all boils down to that old proverb : when arguing with a fool , first make sure the other person is n't doing the same thing .
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in fact , we frequently overestimate our own abilities . researchers have a name for this phenomena , the dunning-kruger effect . this effect explains why more than 100 studies have shown that people display illusory superiority .
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poor performers suffering from the dunning-kruger effect :
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you probably already know everything is made up of little tiny things called atoms or even that each atom is made up of even smaller particles called protons , neutrons and electrons . and you 've probably heard that atoms are small . but i bet you have n't ever thought about how small atoms really are . well , the answer is that they are really , really small . so you ask , just how small are atoms ? to understand this , let 's ask this question : how many atoms are in a grapefruit ? well , let 's assume that the grapefruit is made up of only nitrogen atoms , which is n't at all true , but there are nitrogen atoms in a grapefruit . to help you visualize this , let 's blow up each of the atoms to the size of a blueberry . and then how big would the grapefruit have to be ? it would have to be the same size of -- well , actually , the earth . that 's crazy ! you mean to say that if i filled the earth with blueberries , i would have the same number of nitrogen atoms as a grapefruit ? that 's right ! so how big is the atom ? well , it 's really , really small ! and you know what ? it gets even more crazy . let 's now look inside of each atom -- and thus the blueberry , right ? -- what do you see there ? in the center of the atom is something called the nucleus , which contains protons and neutrons , and on the outside , you 'd see electrons . so how big is the nucleus ? if atoms are like blueberries in the earth , how big would the nucleus be ? you might remember the old pictures of the atom from science class , where you saw this tiny dot on the page with an arrow pointing to the nucleus . well , those pictures , they 're not drawn to scale , so they 're kind of wrong . so how big is the nucleus ? so if you popped open the blueberry and were searching for the nucleus ... you know what ? it would be invisible . it 's too small to see ! ok. let 's blow up the atom -- the blueberry -- to the size of a house . so imagine a ball that is as tall as a two-story house . let 's look for the nucleus in the center of the atom . and do you know what ? it would just barely be visible . so to get our minds wrapped around how big the nucleus is , we need to blow up the blueberry , up to the size of a football stadium . so imagine a ball the size of a football stadium , and right smack dab in the center of the atom , you would find the nucleus , and you could see it ! and it would be the size of a small marble . and there 's more , if i have n't blown your mind by now . let 's consider the atom some more . it contains protons , neutrons and electrons . the protons and neutrons live inside of the nucleus , and contain almost all of the mass of the atom . way on the edge are the electrons . so if an atom is like a ball the size of a football stadium , with the nucleus in the center , and the electrons on the edge , what is in between the nucleus and the electrons ? surprisingly , the answer is empty space . ( wind noise ) that 's right . empty ! between the nucleus and the electrons , there are vast regions of empty space . now , technically there are some electromagnetic fields , but in terms of stuff , matter , it is empty . remember this vast region of empty space is inside the blueberry , which is inside the earth , which really are the atoms in the grapefruit . ok , one more thing , if i can even get more bizarre . since virtually all the mass of an atom is in the nucleus -- now , there is some amount of mass in the electrons , but most of it is in the nucleus -- how dense is the nucleus ? well , the answer is crazy . the density of a typical nucleus is four times 10 to the 17th kilograms per meter cubed . but that 's hard to visualize . ok , i 'll put it in english units . 2.5 times 10 to the 16th pounds per cubic feet . ok , that 's still kind of hard to figure . ok , here 's what i want you to do . make a box that is one foot by one foot by one foot . now let 's go and grab all of the nuclei from a typical car . now , cars on average weigh two tons . how many cars ' nuclei would you have to put into the box to have your one-foot-box have the same density of the nucleus ? is it one car ? two ? how about 100 ? nope , nope and nope . the answer is much bigger . it is 6.2 billion . that is almost equal to the number of people in the earth . so if everyone in the earth owned their own car -- and they do n't -- ( cars honking ) and we put all of those cars into your box ... that would be about the density of a nucleus . so i 'm saying that if you took every car in the world and put it into your one-foot box , you would have the density of one nucleus . ok , let 's review . the atom is really , really , really small . think atoms in a grapefruit like blueberries in the earth . the nucleus is crazy small . now look inside the blueberry , and blow it up to the size of a football stadium , and now the nucleus is a marble in the middle . the atom is made up of vast regions of empty space . that 's weird . the nucleus has a crazy-high density . think of putting all those cars in your one-foot box . i think i 'm tired .
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that 's weird . the nucleus has a crazy-high density . think of putting all those cars in your one-foot box .
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the density of a typical nucleus is equal to ... .
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this is the vhs for an extremely goofy movie . it ’ s the follow up to the cult classic a goofy movie and it ’ s one of my favorite animated films . now , there ’ s a moment in this movie where bobby zimmeruski , max ’ s stoner friend — you know , the one that chugs cheese wiz ? he says , “ do you ever wonder why we ’ re always like ... wearing gloves ? ” that ’ s a damn good question , bobby . let ’ s figure this out . does the question , `` why do animated characters wear gloves ? `` , come up a lot for you ? john : the question rarely comes up , but when it does , there are a number of answers to it . that ’ s john canemaker , he ’ s an animation historian and professor at nyu . the most basic theory is that gloves saved time . john : animation of any kind— even with computers— is a very work-intensive or labor intensive process . `` pardon me . i 've always wondered how they were made . '' at the dawn of animation , everything was hand-drawn over and over and over again . and certain techniques to make the process more efficient shaped the style of the cartoons . john : felix the cat , for example , was a very boxy-looking character . as felix was becoming more popular , the animator bill nolan decided to remove his snout and make him more circular overall . john : and that design—what they call the rubber hose and circle design , very spaghetti-like arms of the characters— continued to the design of mickey mouse as well . this rubber hose and circle aesthetic allowed animators to quickly draw arms , legs , and heads without spending too much time developing realistic details of the character ’ s body—like elbows and knees . a round edge was much faster to draw than an angle , and that certainly applied to hands , with all those fingers and knuckles . but hands posed another a problem for animators in the age of fuzzy black and white film . john : characters were in black and white films difficult to see against their black bodies . take a look at mickey mouse . in 1927 ’ s plane crazy he had black hands and feet , just like felix . he gained shoes by 1928 ’ s steamboat willie and in 1929 he ’ s wearing gloves in the opry house . the rubber hose style of animation is in full effect here . every character is exaggerated , round , and simple . and like many of the glove-wearing cartoon characters of his time , mickey mouse is a non-human doing very human things . in his 1968 biography , `` the disney version '' , walt disney addresses this very issue . he says , `` we did n't want him to have mouse hands , because he was supposed to be more human . so we gave him gloves. ” so in addition to saving time and providing color contrast , gloves bring non-human things to life , making their grand gestures stand out . these 1935 tea kettles from van beuren studio have them . this movie camera does too . when pinocchio is a puppet , he wears gloves . but when he becomes a boy , they disappear . they ’ re no longer needed . but there ’ s another , less practical influence behind cartoon characters ’ white gloves . the opry house is a film about mickey putting on a big vaudeville show . that film and many of the animations that predated it were inextricably linked to vaudeville performance and the blackface minstrel shows of the time . in fact , early animators often performed on vaudeville stages . nicholas sammond writes in birth of an industry that early animated characters like felix the cat , bimbo , bosko , and mickey mouse “ weren ’ t just like minstrels , they were minstrels. ” both the cartoons and the stage characters were portrayed as mischievous and rebellious yet good natured . they wore loose clothes , had painted faces , and … they wore white gloves . in the 1930s vaudeville and blackface minstrelsy declined . white gloves were no longer associated with vaudeville to a new generation of viewers . instead , they were just part of the cartoon style people came to expect . john : there ’ s also the band concert , do you know that film ? it ’ s from 1935 . john : one of the characters is clarabelle cow and she plays the flute and her glove gets stuck in the flute [ chiuckles ] so , really strange without the glove on it . sixty years later goofy takes off his gloves before getting in a pool and it ’ s quite frankly , really disturbing . now what ’ s really bothering me is why daffy duck and many other animated birds don ’ t wear gloves . we might never know . daffy : look , let ’ s not split hairs . why do you even wear gloves ? bugs bunny : because , i ’ ve always worn them . it ’ s who i am . why do you wear that thing around your neck ? touché bugs bunny . touché .
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they ’ re no longer needed . but there ’ s another , less practical influence behind cartoon characters ’ white gloves . the opry house is a film about mickey putting on a big vaudeville show . that film and many of the animations that predated it were inextricably linked to vaudeville performance and the blackface minstrel shows of the time .
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what were the similarities between cartoon characters and the vaudeville / minstrel show characters that they emulated ?
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translator : tom carter reviewer : bedirhan cinar as you can imagine , 400 years ago , navigating the open ocean was difficult . the winds and currents pushed and pulled ships off course , and so sailors based their directions on the port they left , attempting to maintain an accurate record of the ship 's direction and the distance sailed . this process was known as dead reckoning , because being just half a degree off could result in sailing right past the island that lay several miles just over the horizon . this was an easy mistake to make . thankfully , three inventions made modern navigation possible : sextants , clocks and the mathematics necessary to perform the required calculations quickly and easily . all are important . without the right tools , many sailors would be reluctant to sail too far from the sight of land . john bird , an instrument maker in london , made the first device that could measure the angle between the sun and the horizon during the day , called a sextant . knowing this angle was important , because it could be compared to the angle back in england at the exact same time . comparing these two angles was necessary to determine the longitude of the ship . clocks came next . in 1761 , john harrison , an english clockmaker and carpenter , built a clock that could keep accurate time at sea . the timepiece that could maintain accurate time while on a pitching , yawing deck in harsh conditions was necessary in order to know the time back in england . there was one catch though : since such a timepiece was handmade , it was very expensive . so an alternate method using lunar measurements and intense calculations was often used to cut costs . the calculations to determine a ship 's location for each measurement could take hours . but sextants and clocks were n't useful unless sailors could use these tools to determine their position . fortunately , in the 1600s , an amateur mathematician had invented the missing piece . john napier toiled for more than 20 years in his castle in scotland to develop logarithms , a calculation device . napier 's ideas on logarithms involved the form of one over e and the constant 10 to the seventh power . algebra in the early 1600s was not fully developed , and napier 's logarithm of one did not equal zero . this made the calculations much less convenient than logarithms with a base of 10 . henry briggs , a famous mathematician at gresham college in london , read napier 's work in 1614 , and the following year made the long journey to edinburgh to meet napier . briggs showed up unannounced at napier 's castle door and suggested that john switch the base and form of his logarithms into something much simpler . they both agreed that a base of 10 with the log of one equal to zero would greatly simplify everyday calculations . today we remember these as briggs common logarithms . until the development of electric calculating machines in the 20th century , any calculations involving multiplication , division , powers , and extraction of roots with large and small numbers were done using logarithms . the history of logarithms is n't just a lesson in math . there were many players responsible for successful navigation . instrument makers , astronomers , mathematicians , and of course sailors . creativity is n't only about going deep into one 's field of work , it 's about cross-pollination between disciplines too .
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without the right tools , many sailors would be reluctant to sail too far from the sight of land . john bird , an instrument maker in london , made the first device that could measure the angle between the sun and the horizon during the day , called a sextant . knowing this angle was important , because it could be compared to the angle back in england at the exact same time .
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who invented the first device that could measure the distance between the sun and the horizon during the day ?
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as we walk through our daily environments , we 're surrounded by exotic creatures that are too small to see with the naked eye . we usually imagine these microscopic organisms , or microbes , as asocial cells that float around by themselves . but in reality , microbes gather by the millions to form vast communities known as biofilms . natural biofilms are like miniature jungles filled with many kinds of microbes from across the web of life . bacteria and archaea mingle with other microbes like algae , fungi , and protozoa , forming dense , organized structures that grow on almost any surface . when you pad across a river bottom , touch the rind of an aged cheese , tend your garden soil , or brush your teeth , you 're coming into contact with these invisible ecosystems . to see how biofilms come about , let 's watch one as it develops on a submerged river rock . this type of biofilm might begin with a few bacteria swimming through their liquid environment . the cells use rotating flagella to propel towards the surface of the rock , which they attach to with the help of sticky appendages . then , they start producing an extracellular matrix that holds them together as they divide and reproduce . before long , microcolonies arise , clusters of cells sheathed in this slimy , glue-like material . microcolonies grow to become towers , while water channels flow around them , functioning like a basic circulatory system . but why do microbes build such complex communities when they could live alone ? for one thing , microbes living in a biofilm are rooted in a relatively stable microenvironment where they may have access to a nutrient source . there 's also safety in numbers . out in the deep , dark wilderness of the microbial world , isolated microbes face serious risks . predators want to eat them , immune systems seek to destroy them , and there are physical dangers , too , like running out of water and drying up . however , in a biofilm , the extracellular matrix shields microbes from external threats . biofilms also enable interactions between individual cells . when microbes are packed against each other in close proximity , they can communicate , exchange genetic information , and engage in cooperative and competitive social behaviors . take the soil in your garden , home to thousands of bacterial species . as one species colonizes a plant root , its individual cells might differentiate into various subpopulations , each carrying out a specific task . matrix producers pump out the extracellular goo , swimmers assemble flagella and are free to move about or migrate , and spore-formers produce dormant , tough endospores that survive starvation , temperature extremes , and harmful radiation . this phenomenon is called division of labor . ultimately , it gives rise to a sophisticated system of cooperation that 's somewhat like a multicellular organism in itself . but because biofilms often contain many different microbes that are n't closely related to each other , interactions can also be competitive . bacteria launch vicious attacks on their competitors by secreting chemicals into the environment , or by deploying molecular spears to inject nearby cells with toxins that literally blow them up . in the end , competition is all about resources . if one species eliminates another , it keeps more space and food for itself . although this dramatic life cycle occurs beyond the limits of our vision , microbial communities provide humans and other species with tangible , and sometimes even delicious , benefits . microbes make up a major fraction of the biomass on earth and play a critical role within the global ecosystem that supports all larger organisms , including us . they produce much of the oxygen we breath , and are recruited to clean up environmental pollution , like oil spills , or to treat our waste water . not to mention , biofilms are normal and flavor enhancing parts of many of the foods we enjoy , including cheese , salami , and kombucha . so the next time you brush your teeth , bite into that cheese rind , sift through garden soil , or skip a river stone , look as close as you can . imagine the microbial jungles all around you waiting to be discovered and explored .
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however , in a biofilm , the extracellular matrix shields microbes from external threats . biofilms also enable interactions between individual cells . when microbes are packed against each other in close proximity , they can communicate , exchange genetic information , and engage in cooperative and competitive social behaviors .
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what advantages do biofilms provide for the cells that live within them ?
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( music ) aw , thank you , thank you . as you can probably tell , i 'm an astronaut . no , i 'm a dj/producer , as it says on the screen . i am also a high school student , just like many of you guys . how many high school students do we have out here ? ( cheers ) oh , okay ! a good amount . i 'm a proud member of my school 's marching band , and i run track , as well , so if any of you guys are into that , it 's one of my other passions . i have been djing and producing for a little over three years now , and i 've worked with artists that you may know , like avicii , skrillex , major lazer , krewella , porter robinsion , carnage , and many others . how many of you guys like dance music ? show off hands , dance music , oh okay . how many of you guys like rap or trap hip hop ? okay , good amount . jazz ? classical ? that 's good , you guys have smart minds , that 's good . what 's great about djing is that you can combine all these genres into one idea , and what i like to do is combine dance , hip hop , trap , dubstep , even movie samples , and kind of combine them into one set . djing creates this , sort of , combined culture that really unites many fans . a good example of this is skrillex and a $ ap rocky 's collaboration `` wild for the night '' or , most recently , avicii and ella black 's `` wake me up . '' how many of you guys know that song ? it 's a great track . now , what exactly does a dj do ? well , as you just saw earlier , they mix tracks . what i just did was mix a kanye west intro from `` black skinheads '' with a track called `` lrad . '' one of the main goals is to really trigger samples , tracks , or clips and kind of create this long journey . i 'm going to do another little example for you guys right now of what djs call a `` mashup , '' which is taking two or more tracks and combining them into one . this mashup was made famous by a hungarian duo myon & amp ; amp ; shane 54 , and it takes the vocals from krewella 's `` alive . '' how many of you guys know that song ? `` alive '' ? yeah , okay . i 'm going to take the vocals from that track and the song `` language '' by porter robinson . so , let me just play you the vocals first . ( music ) so , that 's the vocals , and here 's the actual track . ( music ) so , what i 'm going to do is i 'm going to fill these vocals on top of the track and create a new song , a kind of combined song , with the two vocals . ( music ) if you turn it down , you can just hear i 'm playing it a capella or just the song by itself . ( music ) now , what i 'm going to do after this drops is change it into another song . one of the most important things about dance music is really the drop , so i 'm going to change it into another song and really catch you by surprise . ( music ) and that 's one example right there . ( applause ) so , as you saw , i took three different songs and kind of combined them into one new idea , which is something plenty of djs do out there on the professional circuit . there are plenty of ways to get started djing . one of the main things i did was really take the time to study djs that inspired me . whether it was watching podcasts , watching live sets , or just really looking them up online . i really tried to take in what it meant to be a fantastic dj . one of the best ways to really learn is to ask a friend , you know , a friend who knows how to dj . just go over there , ask him a few questions . if no that , thankfully we have a lot of great online resources . one of the things you can do is check out youtube , check out some demonstrations . now , many djs , a high percentage of them , check out beatport or soundcloud to find a lot of the tracks . there are also many other blog sites , such as billboard 's code , edmtunes , edm sauce , or dancing astronaut . now , there are multiple ways to dj , and what could originally only be done on turntables and vinyl , by legends such as larry levan , grandmaster flash , and paul oakenfold , can now be done with many more pieces of equipment , such as cdjs , which are , sort of , digital turntables and what i learned on and what i still use to this day . there are many other amazing programs now , such as ableton , traktor pro , serato , or even apps for tablets and touchscreens . there are many hardware systems just like my apc40 here that can launch samples , clips and tracks . you can also just use turntables , cdjs , an s4 controller , or an novation launchpad . and all of these really kind of do the same thing , and that 's mix tracks . so , what i 'm going to do now is show you guys another mix demonstration . i 'm going to start with one of my own songs that i did with my friend matt dzyacky , and from there i 'm going to go in a sort of medley of different tracks and show you the different styles of mixing that you can do . ( music ) so i 'll show you guys when i start mixing the new track , so you can hear it coming in . ( music ) you can hear in the back , a new song is mixing in . ( music ) now , another thing that djs use is what 's called a mixer , and a mixer has many different effects , such as a beat roll , filter effects , and any other different ones . there 's plenty of effects to use . ( music ) so , now i 'm going into a new song , and after this drops , i 'm going to drop it in another song and kind of change it up . ( music ) and that 's a new song bite . ( music ) so i 'm just going to straight mash up another song right when this one breaks down . ( music ) now , if i want to change up the music , let 's say , throw in some new beats , i can just choose a trap beat i want to throw over the breakdown . ( music ) so , i get ready to throw in my new beats now . ( music ) and that is the end of that demo . ( applause ) thank you , thank you ! now , the great thing about technologies now is whether it 's a two dollar app or a couple hundred dollar equipment , which i 'm sure most parents wo n't want to buy for their child , is that almost anyone who has a passion for djing and a passion for the music and who might want to pursue a career in it really has the ability to , well , pursue it , such as myself . you can start with an app on a tablet or an app on your phone , even , an app on your ipad , and then move on to bigger equipment . the opportunities are endless , and , as you saw , you can mix many different styles of music . so , thank you !
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( applause ) so , as you saw , i took three different songs and kind of combined them into one new idea , which is something plenty of djs do out there on the professional circuit . there are plenty of ways to get started djing . one of the main things i did was really take the time to study djs that inspired me .
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explain why it 's easy to get started as a dj .
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translator : andrea mcdonough reviewer : bedirhan cinar every cell in your body is separated from those around it by its outermost layer , its membrane . a cell membrane must be both sturdy and flexible . imagine a membrane made of metal - great at keeping the cell 's guts inside , but horrible at letting materials flow in and out . but a membrane made of fishnet stocking would go too far in the opposite direction - leaky , but easily torn . so , the ideal membrane falls somewhere in the middle . over the past few centuries , we 've learned a lot about the way membranes work . the tale starts in the late 1800 's when , according to legend , a german woman named agnes pockels was doing dishes . her observation , that not all detergents dissolve grease in the same way , piqued her curiosity , so she made careful measurements of the size of soapy films that formed on the surface of a metal tray filled with water . later , in the 1920 's , ge scientists irving langmuir and katharine blodgett reexamined the problem with a more elaborate contraption and found that those tiny slicks were in fact a single layer of oil molecules . each oil molecule has one side that loves water and floats on the surface , and one side that loathes water and protrudes into the air . so what does it have to do with cell membranes ? well , at the turn of the 20th century , chemists charles overton and hans meyer demonstrated that the cell membrane is composed of substances that , like oil , have a water-loving part and a water-loathing part . we now call these substances lipids . in 1925 , two scientists , evert gorter and francois grendel , pushed our understanding further . they designed an experiment meant to test whether cell membranes are made of only one layer of lipids , a monolayer , or two layers stacked on top of one another , called a bilayer . gorter and grendel drew blood from a dog , a sheep , a rabbit , a goat , a guinea pig , and human volunteers . from each of these samples , they extracted all the lipids from all the red blood cells and placed a few drops of this extract on a tray of water . true to form , the lipids , like oil , spread out into a monolayer , whose size gorter and grendel could measure . if they compared the surface area of that monolayer to the surface area to the intact red blood cells , they 'd be able to tell whether the red blood cell membrane is one or two layers thick . to understand the design of their experiment , imagine looking down at a sandwich . if you measure the surface area of what you see , you 'll get the dimensions of a single slice of bread even though there are two slices , one stacked perfectly atop the other . but , if you open the sandwich and place the two slices side by side , you get twice the surface area . the gorter and grendel experiment is basically the same idea . the open sandwich is the monolayer formed by extracted cellular lipids spreading out into a sheet . the closed sandwich is the intact red blood cell membrane . low and behold , they observed a two-to-one ratio , proving beyond the shadow of a doubt that a cell membrane is a bilayer , which when unstacked , yields a monolayer twice its size . so almost 30 years before the double-helix structure of dna was elucidated , a single experiment involving fancy versions of household materials enabled deep insight into the basic architecture of the cell .
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translator : andrea mcdonough reviewer : bedirhan cinar every cell in your body is separated from those around it by its outermost layer , its membrane . a cell membrane must be both sturdy and flexible . imagine a membrane made of metal - great at keeping the cell 's guts inside , but horrible at letting materials flow in and out . but a membrane made of fishnet stocking would go too far in the opposite direction - leaky , but easily torn .
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watch mina bissell 's ted talk ( found in the dig deeper ) and then explain some reasons why our understanding of the cell membrane matters so much .
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light is the fastest thing we know . it 's so fast that we measure enormous distances by how long it takes for light to travel them . in one year , light travels about 6,000,000,000,000 miles , a distance we call one light year . to give you an idea of just how far this is , the moon , which took the apollo astronauts four days to reach , is only one light-second from earth . meanwhile , the nearest star beyond our own sun is proxima centauri , 4.24 light years away . our milky way is on the order of 100,000 light years across . the nearest galaxy to our own , andromeda , is about 2.5 million light years away space is mind-blowingly vast . but wait , how do we know how far away stars and galaxies are ? after all , when we look at the sky , we have a flat , two-dimensional view . if you point you finger to one star , you ca n't tell how far the star is , so how do astrophysicists figure that out ? for objects that are very close by , we can use a concept called trigonometric parallax . the idea is pretty simple . let 's do an experiment . stick out your thumb and close your left eye . now , open your left eye and close your right eye . it will look like your thumb has moved , while more distant background objects have remained in place . the same concept applies when we look at the stars , but distant stars are much , much farther away than the length of your arm , and the earth is n't very large , so even if you had different telescopes across the equator , you 'd not see much of a shift in position . instead , we look at the change in the star 's apparent location over six months , the halfway point of the earth 's yearlong orbit around the sun . when we measure the relative positions of the stars in summer , and then again in winter , it 's like looking with your other eye . nearby stars seem to have moved against the background of the more distant stars and galaxies . but this method only works for objects no more than a few thousand light years away . beyond our own galaxy , the distances are so great that the parallax is too small to detect with even our most sensitive instruments . so at this point we have to rely on a different method using indicators we call standard candles . standard candles are objects whose intrinsic brightness , or luminosity , we know really well . for example , if you know how bright your light bulb is , and you ask your friend to hold the light bulb and walk away from you , you know that the amount of light you receive from your friend will decrease by the distance squared . so by comparing the amount of light you receive to the intrinsic brightness of the light bulb , you can then tell how far away your friend is . in astronomy , our light bulb turns out to be a special type of star called a cepheid variable . these stars are internally unstable , like a constantly inflating and deflating balloon . and because the expansion and contraction causes their brightness to vary , we can calculate their luminosity by measuring the period of this cycle , with more luminous stars changing more slowly . by comparing the light we observe from these stars to the intrinsic brightness we 've calculated this way , we can tell how far away they are . unfortunately , this is still not the end of the story . we can only observe individual stars up to about 40,000,000 light years away , after which they become too blurry to resolve . but luckily we have another type of standard candle : the famous type 1a supernova . supernovae , giant stellar explosions are one of the ways that stars die . these explosions are so bright , that they outshine the galaxies where they occur . so even when we ca n't see individual stars in a galaxy , we can still see supernovae when they happen . and type 1a supernovae turn out to be usable as standard candles because intrinsically bright ones fade slower than fainter ones . through our understanding of this relationship between brightness and decline rate , we can use these supernovae to probe distances up to several billions of light years away . but why is it important to see such distant objects anyway ? well , remember how fast light travels . for example , the light emitted by the sun will take eight minutes to reach us , which means that the light we see now is a picture of the sun eight minutes ago . when you look at the big dipper , you 're seeing what it looked like 80 years ago . and those smudgy galaxies ? they 're millions of light years away . it has taken millions of years for that light to reach us . so the universe itself is in some sense an inbuilt time machine . the further we can look back , the younger the universe we are probing . astrophysicists try to read the history of the universe , and understand how and where we come from . the universe is constantly sending us information in the form of light . all that remains if for us to decode it .
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standard candles are objects whose intrinsic brightness , or luminosity , we know really well . for example , if you know how bright your light bulb is , and you ask your friend to hold the light bulb and walk away from you , you know that the amount of light you receive from your friend will decrease by the distance squared . so by comparing the amount of light you receive to the intrinsic brightness of the light bulb , you can then tell how far away your friend is . in astronomy , our light bulb turns out to be a special type of star called a cepheid variable . these stars are internally unstable , like a constantly inflating and deflating balloon .
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consider you are x units in distance from a light source . you receive y unit of light per unit time . you have to be _____ x units in distance from the light source in order to receive 4y unit of light per unit time .
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if you line up the entire text of `` moby dick , '' which was published in 1851 , into a giant rectangle , you may notice some peculiar patterns , like these words , which seem to predict the assassination of martin luther king , or these references to the 1997 death of princess di . so , was herman melville a secret prophet ? the answer is no , and we know that thanks to a mathematical principle called ramsey theory . it 's the reason we can find geometric shapes in the night sky , it 's why we can know without checking that at least two people in london have exactly the same number of hairs on their head , and it explains why patterns can be found in just about any text , even vanilla ice lyrics . so what is ramsey theory ? simply put , it states that given enough elements in a set or structure , some particular interesting pattern among them is guaranteed to emerge . as a simple example , let 's look at what 's called the party problem , a classic illustration of ramsey theory . suppose there are at least six people at a party . amazingly enough , we can say for sure that some group of three of them either all know each other , or have never met before , without knowing a single thing about them . we can demonstrate that by graphing out all the possibilities . each point represents a person , and a line indicates that the pair know each other . every pair only has two possibilities : they either know each other or they do n't . there are a lot of possibilities , but every single one has the property that we 're looking for . six is the lowest number of guests where that 's guaranteed to be the case , which we can express like this . ramsey theory gives us a guarantee that such a minimum number exists for certain patterns , but no easy way to find it . in this case , as the total number of guests grows higher , the combinations get out of control . for instance , say you 're trying to find out the minimum size of a party where there 's a group of five people who all know each other or all do n't . despite five being a small number , the answer is virtually impossible to discover through an exhaustive search like this . that 's because of the sheer volume of possibilities . a party with 48 guests has 2^ ( 1128 ) possible configurations , more than the number of atoms in the universe . even with the help of computers , the best we know is that the answer to this question is somewhere between 43 and 49 guests . what this shows us is that specific patterns with seemingly astronomical odds can emerge from a relatively small set . and with a very large set , the possibilities are almost endless . any four stars where no three lie in a straight line will form some quadrilateral shape . expand that to the thousands of stars we can see in the sky , and it 's no surprise that we can find all sorts of familiar shapes , and even creatures if we look for them . so what are the chances of a text concealing a prophecy ? well , when you factor in the number of letters , the variety of possible related words , and all their abbreviations and alternate spellings , they 're pretty high . you can try it yourself . just pick a favorite text , arrange the letters in a grid , and see what you can find . the mathematician t.s . motzkin once remarked that , `` while disorder is more probable in general , complete disorder is impossible . '' the sheer size of the universe guarantees that some of its random elements will fall into specific arrangements , and because we evolved to notice patterns and pick out signals among the noise , we are often tempted to find intentional meaning where there may not be any . so while we may be awed by hidden messages in everything from books , to pieces of toast , to the night sky , their real origin is usually our own minds .
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it 's the reason we can find geometric shapes in the night sky , it 's why we can know without checking that at least two people in london have exactly the same number of hairs on their head , and it explains why patterns can be found in just about any text , even vanilla ice lyrics . so what is ramsey theory ? simply put , it states that given enough elements in a set or structure , some particular interesting pattern among them is guaranteed to emerge .
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how might one use ramsey theory in ‘ the real world ’ ?
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if you live on the east coast of the united states , you 've spent the last 17 years of your life walking , eating and sleeping above a dormant army of insects . these are the cicadas . every 17 years , billions of them emerge from the ground to do three things : molt , mate and die . there are 15 different broods of cicadas out there , grouped by when they 'll emerge from the ground . some of these broods are on a 13-year cycle , others are on a 17-year clock . either way , the cicadas live underground for most of their lives , feeding on the juices of plant roots . when it 's time to emerge , the adults begin to burrow their way out of the ground and up to the surface , where they 'll live for just a few weeks . during these weeks , though , everybody will know the cicadas have arrived . there will be billions of them . and they 're loud . male cicadas band together to call for female mates , and their collective chorus can reach up to 100 decibels -- as loud as a chain saw . in fact , if you happen to be using a chain saw or a lawn mower , male cicadas will flock to you , thinking that you 're one of them . now , like most things in nature , the cicadas do n't arrive without a posse . there are all sort of awesome and gross predators and parasites that come along with the buzzing bugs . take the fungus massospora for example . this little white fungus buries itself in the cicada 's abdomen and eats the bug alive , leaving behind its spores . when those spores rupture , they burst out of the still-alive cicada , turning the bug into a flying saltshaker of death , raining spores down upon its unsuspecting cicada neighbors . but while we know pretty precisely when the cicadas will arrive and fade away , we 're still not totally certain of why . there are certain advantages to having your entire species emerge at once , of course . the sheer number of cicadas coming out of the ground is so overwhelming to predators , it is essentially guaranteed that a few bugs will survive and reproduce . and since cicadas emerge every 13 or 17 years , longer than the lifespan of many of their predators , the animals that eat them do n't learn to depend on their availability . but why 13 and 17 years , instead of 16 or 18 or 12 ? well , that part no one really knows . it 's possible the number just happened by chance , or , perhaps , cicadas really love prime numbers . eventually , the cicadas will mate and slowly die off , their call fading into the distance . the eggs they lay will begin the cycle again , their cicada babies burrowing into the earth , feeding on plant juice , and waiting for their turn to darken the skies and fill the air with their songs . in 17 years , they 'll be ready . will you ?
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if you live on the east coast of the united states , you 've spent the last 17 years of your life walking , eating and sleeping above a dormant army of insects . these are the cicadas . every 17 years , billions of them emerge from the ground to do three things : molt , mate and die .
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why do cicadas come out so infrequently ?
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translator : tom carter reviewer : bedirhan cinar dialogue gives a story color , makes it exciting and moves it forward . romeo : o , wilt thou leave me so unsatisfied ? juliet : what satisfaction canst thou have tonight ? romeo : the exchange of thy love 's faithful vows for mine . without dialogue : ( cricket sounds ) so what goes into writing effective dialogue ? well , there are social skills : making friends , solving conflicts , being pleasant and polite . we wo n't be using any of those today . instead , we 'll be working on -- let 's call them `` anti-social skills . '' if you 're a writer , you may already have a few of these . the first is eavesdropping . if you 're riding a bus and hear an interesting conversation , you could write it all down . of course , when you write fiction , you 're not describing real people , you 're making up characters . but sometimes the words you overhear can give you ideas . `` i did not , '' says one person . `` i saw you , '' the other replies . who might be saying those words ? maybe it 's two kids in a class , and the boy thinks the girl pushed him . maybe it 's a couple , but one of them is a vampire , and the woman vampire saw the man flirting with a zombie . or maybe not . maybe the characters are a teenager and his mother , and they 're supposed to be vegetarians , but the mother saw him eating a burger . so let 's say you 've decided on some characters . this is anti-social skill number two : start pretending they 're real . what are they like ? where are they from ? what music do they listen to ? spend some time with them . if you 're on a bus , think about what they might be doing if they were there too . would they talk on the phone , listen to music , draw pictures , sleep ? what we say depends on who we are . an older person might speak differently than a younger person . someone from the south might speak differently than someone from the north . once you know your characters , you can figure out how they talk . at this stage , it 's helpful to use anti-social skill number three : muttering to yourself . when you speak your character 's words , you can hear whether they sound natural , and fix them if necessary . remember , most people are usually pretty informal when they speak . they use simple language and contractions . so , `` do not attempt to lie to me '' sounds more natural as `` do n't try to lie to me . '' also keep it short . people tend to speak in short bursts , not lengthy speeches . and let the dialogue do the work . ask yourself : do i really need that adverb ? for instance , `` 'your money or your life , ' she said threateningly . '' here , `` threateningly '' is redundant , so you can get rid of it . but if the words and the actions do n't match , an adverb can be helpful . `` 'your money or your life , ' she said lovingly . '' so , to recap : first , eavesdrop . next , pretend imaginary people are real . finally , mutter to yourself , and write it all down . you already have everything you need . this is fictional dialogue , or `` how to hear voices in your head . ''
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romeo : the exchange of thy love 's faithful vows for mine . without dialogue : ( cricket sounds ) so what goes into writing effective dialogue ? well , there are social skills : making friends , solving conflicts , being pleasant and polite .
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imagine you are writing dialogue for two teenagers at a party . which of the following lines sounds more natural ?
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in 479 bc , when persian soldiers besieged the greek city of potidaea , the tide retreated much farther than usual , leaving a convenient invasion route . but this was n't a stroke of luck . before they had crossed halfway , the water returned in a wave higher than anyone had ever seen , drowning the attackers . the potiidaeans believed they had been saved by the wrath of poseidon . but what really saved them was likely the same phenomenon that has destroyed countless others : a tsunami . although tsunamis are commonly known as tidal waves , they 're actually unrelated to the tidal activity caused by the gravitational forces of the sun and moon . in many ways , tsunamis are just larger versions of regular waves . they have a trough and a crest , and consist not of moving water , but the movement of energy through water . the difference is in where this energy comes from . for normal ocean waves , it comes from wind . because this only affects the surface , the waves are limited in size and speed . but tsunamis are caused by energy originating underwater , from a volcanic eruption , a submarine landslide , or most commonly , an earthquake on the ocean floor caused when the tectonic plates of the earth 's surface slip , releasing a massive amount of energy into the water . this energy travels up to the surface , displacing water and raising it above the normal sea level , but gravity pulls it back down , which makes the energy ripple outwards horizontally . thus , the tsunami is born , moving at over 500 miles per hour . when it 's far from shore , a tsunami can be barely detectable since it moves through the entire depth of the water . but when it reaches shallow water , something called wave shoaling occurs . because there is less water to move through , this still massive amount of energy is compressed . the wave 's speed slows down , while its height rises to as much as 100 feet . the word tsunami , japanese for `` harbor wave , '' comes from the fact that it only seems to appear near the coast . if the trough of a tsunami reaches shore first , the water will withdraw farther than normal before the wave hits , which can be misleadingly dangerous . a tsunami will not only drown people near the coast , but level buildings and trees for a mile inland or more , especially in low-lying areas . as if that were n't enough , the water then retreats , dragging with it the newly created debris , and anything , or anyone , unfortunate enough to be caught in its path . the 2004 indian ocean tsunami was one of the deadliest natural disasters in history , killing over 200,000 people throughout south asia . so how can we protect ourselves against this destructive force of nature ? people in some areas have attempted to stop tsunamis with sea walls , flood gates , and channels to divert the water . but these are not always effective . in 2011 , a tsunami surpassed the flood wall protecting japan 's fukushima power plant , causing a nuclear disaster in addition to claiming over 18,000 lives . many scientists and policy makers are instead focusing on early detection , monitoring underwater pressure and seismic activity , and establishing global communication networks for quickly distributing alerts . when nature is too powerful to stop , the safest course is to get out of its way .
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when it 's far from shore , a tsunami can be barely detectable since it moves through the entire depth of the water . but when it reaches shallow water , something called wave shoaling occurs . because there is less water to move through , this still massive amount of energy is compressed .
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what exactly is a wave ?
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there 's a play so powerful that an old superstition says its name should never even be uttered in a theater , a play that begins with witchcraft and ends with a bloody severed head , a play filled with riddles , prophesies , nightmare visions , and lots of brutal murder , a play by william shakespeare sometimes referred to as the `` scottish play '' or the `` tragedy of macbeth . '' first performed at the globe theater in london in 1606 , `` macbeth '' is shakespeare 's shortest tragedy . it is also one of his most action-packed . in five acts , he recounts a story of a scottish nobleman who steals the throne , presides over a reign of terror , and then meets a bloody end . along the way , it asks important questions about ambition , power , and violence that spoke directly to the politics of shakespeare 's time and continue to echo in our own . england in the early 17th century was politically precarious . queen elizabeth i died in 1603 without producing an heir , and in a surprise move , her advisors passed the crown to james stewart , king of scotland . two years later , james was subject to an assassination attempt called the gunpowder plot . questions of what made for a legitimate king were on everyone 's lips . so shakespeare must have known he had potent material when he conflated and adapted the stories of a murderous 11th century scottish king named macbeth and those of several other scottish nobles . he found their annals in hollinshed 's `` chronicles , '' a popular 16th century history of britain and ireland . shakespeare would also have known he needed to tell his story in a way that would immediately grab the attention of his diverse and rowdy audience . the globe welcomed all sections of society . wealthier patrons watched the stage from covered balconies while poorer people paid a penny to take in the show from an open-air section called the pit . talking , jeering , and cheering was common during performances . there are even accounts of audiences throwing furniture when plays were flops . so `` macbeth '' opens with a literal bang . thunder cracks and three witches appear . they announce they 're searching for a scottish nobleman and war hero named macbeth , then fly off while chanting a curse that predicts a world gone mad . `` fair is foul and foul is fair . hover through the fog and filthy air . '' as seen later , they find macbeth and his fellow nobleman banquo . `` all hail macbeth , '' they prophesize , `` that shalt be king hereafter ! '' `` king ? '' macbeth wonders . just what would he have to do to gain the crown ? macbeth and his wife lady macbeth soon chart a course of murder , lies , and betrayal . in the ensuing bloodbath , shakespeare provides viewers with some of the most memorable passages in english literature . `` out , damned spot ! out , i say ! '' lady macbeth cries when she believes she ca n't wipe her victim 's blood off her hands . her obsession with guilt is one of many themes that runs through the play , along with the universal tendency to abuse power , the endless cycles of violence and betrayal , the defying political conflict . as is typical with shakespeare 's language , a number of phrases that got their start in the play have been repeated so many times that they now feel commonplace . they include `` the milk of human kindness , '' `` what 's done is done , '' and the famous witches ' spell , `` double , double toil and trouble ; fire burn , and caldron bubble . '' but shakespeare saves the juiciest bit of all for macbeth himself . towards the end of the play , macbeth reflects on the universality of death and the futility of life . `` out , out , brief candle ! '' he laments . `` life 's but a walking shadow , a poor player that struts and frets his hour upon the stage and then is heard no more . it is a tale told by an idiot , full of sound and fury signifying nothing . '' life may be a tale told my an idiot , but `` macbeth '' is not . shakespeare 's language and characters have entered our cultural consciousness to a rare extent . directors often use the story to shed light on abuses of power , ranging from the american mafia to dictators across the globe . the play has been adapted to film many times , including akira kurosawa 's `` throne of blood , '' which takes place in feudal japan , and a modernized version called `` scotland , pa , '' in which macbeth and his rivals are managers of competing fast food restaurants . no matter the presentation , questions of morality , politics , and power are still relevant today , and so , it seems , is shakespeare 's `` macbeth . ''
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`` king ? '' macbeth wonders . just what would he have to do to gain the crown ?
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`` macbeth '' becomes ambitious after hearing a prophecy from :
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